WO1995018354A1

WO1995018354A1 - Method and device for measuring position

Info

Publication number: WO1995018354A1
Application number: PCT/JP1994/002236
Authority: WO
Inventors: Shinichi Fujitani
Original assignee: Nakanishi Metal Works Co., Ltd.
Priority date: 1993-12-28
Filing date: 1994-12-26
Publication date: 1995-07-06
Also published as: TW250542B

Abstract

The position of an object to be measured is found based on the distances from multiple transmitters arranged at prescribed intervals to a receiver attached to the object by receiving ultrasonic waves having different frequencies and transmitted intermittently and nearly synchronously from the transmitters, passing the received signals through multiple band-pass filters having different narrow-band characteristics with different center frequencies, detecting received signals from the transmitters, and then, finding the distances based on the times elapsed after the ultrasonic waves are transmitted from the transmitters until the received signals from the transmitters are detected.

Description

Description Position measurement method and device Technical field

The present invention relates to a two-dimensional or three-dimensional position measuring method and apparatus using ultrasonic waves. Background technology

As this type of position measurement method, a single transmitter attached to an object to be measured intermittently transmits ultrasonic waves of a constant frequency, and a plurality of receivers in which the ultrasonic waves are arranged at predetermined intervals And measure the elapsed time from the start time of the transmission of ultrasonic waves by the transmitter to the reception time of the ultrasonic waves by each receiver, and calculate the distance from the transmitter to each receiver based on these times. It is known to obtain the position of the measured object based on these distances. In this case, three receivers are used for three-dimensional position measurement and two receivers for two-dimensional position measurement.

In addition, the relationship between the transmitter and the receiver was reversed, and ultrasonic waves were intermittently transmitted from a plurality of transmitters arranged at predetermined intervals, and these ultrasonic waves were attached to the object to be measured. One receiver receives and measures the elapsed time from the start time of ultrasonic transmission by each transmitter to the reception time of ultrasonic wave by the receiver.Based on these times, the measured object is measured in the same manner as above. It is also known to determine the position of Also in this case, three transmitters are used for three-dimensional position measurement and two transmitters are used for two-dimensional position measurement.

In the former method, in which the transmitter is attached to the measured object, A single ultrasonic burst transmitted from a transmitter is received by multiple receivers, and the distance to the transmitter can be measured simultaneously by each receiver, so that the measurement cycle can be shortened. However, depending on the relative angle between the transmitting surface and the receiving surface, there is a problem that measurement errors occur due to the strong influence of reflected waves. Considering the case where the positions of a plurality of objects to be measured are measured, if an ultrasonic wave of the same frequency is simultaneously transmitted from a transmitter attached to each of the objects to be measured, Can't tell if it's from a vessel. Therefore, it is necessary to transmit ultrasonic waves having different frequencies from the transmitters of a plurality of objects to be measured, and to measure the positions of a plurality of objects to be measured in a time-division manner. It is difficult to measure the position of the measurement object. Furthermore, since the transmitter is attached to the object to be measured, it is difficult to make the object to be measured cordless.

The latter method, in which the receiver is mounted on the object to be measured, does not have the above problems, but has the following problems. In other words, when the frequency of the ultrasonic waves transmitted from a plurality of transmitters is the same, if the ultrasonic waves are transmitted from each transmitter at the same time, it cannot be distinguished from which transmitter the ultrasonic waves received by the receiver are. Therefore, it is necessary to transmit the ultrasonic waves from each transmitter and measure the distance in a time-division manner. By the way, when a three-dimensional position measurement method is applied to a presentation device such as a conference room event venue, the measurement cycle is about 2 Omsec in a relatively large space of about 3 m on one side. Therefore, it is necessary to perform position measurement with a measurement accuracy of about ± 1 mm. However, as described above, if distance measurement from three transmitters is performed in a time-division manner, it takes 9 m for one transmitter to propagate ultrasonic waves over a distance of 3 m. It takes a time of sec, and the three transmitters require a time of 27 msec just for the propagation of the ultrasonic wave. Therefore, the measurement cycle cannot be reduced to 2 O msec or less. If the frequencies of the ultrasonic waves transmitted from the three transmitters are different from each other, the ultrasonic waves are transmitted simultaneously from these transmitters and the position is measured in a relatively large space with a measurement cycle of about 2 Omsec. Can be. By the way, especially when performing three-dimensional position measurement, strong ultrasonic directivity is not preferable. However, the directivity of the ultrasonic wave increases as the frequency increases, and the frequency of the ultrasonic wave that can be used for position measurement in a three-dimensional space is about 40 kHz or less. In addition, a high frequency of about 25 kHz or more is required to distinguish it from the audible band. For this reason, the frequencies of ultrasonic waves that can be actually used are relatively close to each other, for example, 40, 32, and 25 kHz. When using ultrasonic waves of such close frequencies, it is difficult to completely separate the ultrasonic waves of each frequency using a normal band filter, and the effects of other ultrasonic waves and extraneous noise As a result, there is a problem that the measurement accuracy is reduced. Therefore, it is difficult to perform highly accurate position measurement in a relatively short space within a relatively large space.

An object of the present invention is to solve the above problems and to provide a position measuring method and apparatus capable of performing a wide range of position measurement with high accuracy in a short measurement period by using a method of mounting a receiver on an object to be measured. It is in. Disclosure of the invention

The position measurement method according to the present invention intermittently transmits ultrasonic waves having different frequencies from a plurality of transmitters arranged at a predetermined interval. And at almost the same time, these ultrasonic waves are received by a single receiver attached to the object to be measured, and the received signals of the receivers are band-pass filters having a plurality of narrow-band characteristics having different center frequencies. , The received signal for each ultrasonic wave from each transmitter is individually detected, and the time elapsed from the start of transmission of ultrasonic waves by each transmitter to the detection time of the corresponding received signal for each transmitter is detected. The distance from each transmitter to the receiver is calculated based on the distance, and the position of the object to be measured is calculated based on these distances.o

A position measuring method according to the present invention measures, for example, the position of an object to be measured in a coordinate system based on a display screen of an image display device.

A position measuring method according to the present invention measures, for example, a three-dimensional position of an object to be measured in a predetermined space around an imaging device whose angle can be adjusted based on position information.

A position measuring device according to the present invention includes a plurality of transmitters arranged at predetermined intervals, one receiver attached to an object to be measured, and intermittently transmitting ultrasonic waves having different frequencies from each transmitter. Transmitters that transmit at almost the same time.Received signals of receivers are passed through multiple bandpass filters with different narrowband characteristics with different center frequencies to individually detect received signals for each transmitter for ultrasonic waves from each transmitter. The distance from each transmitter to the receiver and the measured object based on the elapsed time from the transmission start time of each transmitter and the detection time of the corresponding reception signal for each transmitter. It is characterized by having a processing device for obtaining the position.

Preferably, the band filter is at the same frequency as the corresponding ultrasound. Of the two ultrasonic transducers, and the resonators of these ultrasonic transducers are arranged facing each other at a distance of about one wavelength of the corresponding ultrasonic waves. An input signal is applied to the electrode, and an output signal is extracted from the electrode of the other transducer.

For example, an operation section provided with an operation switch means for operating the object to be measured by hand, an expandable and contractible section having a base end fixed to the operation section, and an expandable and contractible section It has a detector fixed to the tip of the unit, and a receiver is attached to the detector.

According to the method and apparatus of the present invention, ultrasonic waves having different frequencies are transmitted from a plurality of transmitters almost simultaneously, and the distance from each transmitter to the receiver is measured almost simultaneously. The measurement cycle can be shortened as compared with the case where the distance from the object is measured by time division. In addition, since the received signal of the receiver is passed through a plurality of band filters having narrow band characteristics having different center frequencies from each other, the received signal for each transmitter with respect to the ultrasonic wave from each transmitter is individually detected. Even with the use of nearby ultrasonic waves, there is little influence from other ultrasonic waves or external noise, and highly accurate measurement is possible. Therefore, a method of attaching a receiver to an object to be measured can be used to accurately measure a wide range of positions in a short measurement period.

The bandpass filter has two piezoelectric ultrasonic transducers at the same frequency as the corresponding ultrasonic wave, and the resonators of these ultrasonic transducers are separated by about one wavelength of the corresponding ultrasonic wave. Input signal is applied to the electrode of one of the transducers and output from the electrode of the other transducer. When the signal is taken out, it has excellent blocking characteristics, is less affected by other ultrasonic waves and extraneous noise, and enables more accurate measurement .

An operation section provided with an operation switch means for operating the object to be measured by holding it in a hand, an expandable and contractible section having a base end fixed to the operation section, and a distal end of the expandable section When the receiver is attached to the detector, it can easily indicate a distant object directly with the telescopic part extended. You can easily input handwriting in the contracted state. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic perspective view of a presentation device showing one embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of the presentation device of FIG. FIG. 3 is a side view showing an example of the pointing member. FIG. 4 is a block diagram showing an example of the configuration of the second receiving circuit. FIG. 5 is a longitudinal sectional view showing one example of the bandpass filter. Fig. 6 is a graph showing the cutoff characteristics of the band filter. <Fig. 7 is a graph showing the cutoff characteristics required for the band filter when no AOC means is provided. FIG. 8 is a timing chart showing an example of a transmission signal. Figure 9 is a timing chart showing the received signal for each transmitter when the transmitted signal is detuned and when it is not detuned. Figure 10 is a timing chart showing the smooth envelope of the half-wave rectified wave of the received signal for each transmitter when the transmitted signal is detuned and when not detuned. Fig. 11 is a timing chart showing a stepped envelope of a half-wave rectified wave of a received signal for each transmitter. Fig. 12 shows a stepped envelop This is a timing chart showing a stepped envelope with a large gap between the loop and the step. Figure 13 is a timing chart showing the relationship between the stepped envelope with the difference between steps increased and the threshold. Figure 14 is a timing chart showing the relationship between the smooth envelope and the threshold value when the received signal levels are different. Figure 15 is a timing chart showing the relationship between the smooth envelope of the received signal and the fluctuation of the threshold. FIG. 16 is an explanatory diagram showing a method of operating the indicating member when instructing the figure deformation. FIG. 17 is an explanatory diagram showing the relationship between the operation of the pointing member and the figure deformation. FIG. 18 is a block diagram corresponding to FIG. 2 showing another embodiment of the present invention. FIG. 19 is a block diagram corresponding to FIG. 2, showing still another embodiment of the present invention. FIG. 20 is a block diagram corresponding to FIG. 2 showing still another embodiment of the present invention. FIG. 21 is a block diagram corresponding to FIG. 2 showing still another embodiment of the present invention. FIG. 22 is a side view showing another example of the indicating member in a state where the expansion and contraction portion is extended. FIG. 23 is a side view of the pointing member of FIG. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 schematically shows an example of the appearance of a presentation device using the method and device of the present invention. Fig. 2 shows the functional configuration of the presentation device.

This presentation device is installed in a room such as a conference room event venue. The presentation device is a display provided at a predetermined location on the wall (1) of the room. Screen (2), Two 2D measurement transmitters (3a) (3b) arranged at two locations on the screen (2) at predetermined intervals, and the ceiling in the room Three three-dimensional measurement transmitters (5a), (5b), and (5c) arranged at predetermined intervals on three locations on surface U). Television cameras located at specific locations on ceiling (4) (Imaging device) (6), Direction adjustment device (7) for changing the direction of the TV camera (6), Instruction member (8) for the speaker (not shown) to operate by hand, Indoor desk It consists of an image display device (10) and a control unit (11) installed above (9). Two-dimensional measurement transmitters (abbreviated as two-dimensional transmitters) are collectively referred to by reference numeral (3), and when it is necessary to distinguish them, the first two-dimensional transmitter (3a) and the second It will be called the transmitter (3b). The three-dimensional measurement transmitters (abbreviated as three-dimensional transmitters) are collectively referred to by reference numeral (5), and when it is necessary to distinguish them, the first three-dimensional transmitter (5a) and the second three-dimensional transmitter, respectively. (5b) and the third transmitter (5c). The presentation device has the following functions: screen (2), pointing member (8), position measuring device (12), image display device (10), television camera (6), It consists of an adjusting device (7) and a control device (13).

The display screen (2) is not limited to the one in this embodiment as long as it can display an image. For example, a blackboard-shaped display board may be used as a display screen. Also, a white wall surface may be used as a display screen. In that case, the presentation device does not need to be provided with a separate display screen. The image display device (10) is a screen display based on control signals from the control device (13), image information, and the like. (2) It is for displaying a desired image on it, and is composed of, for example, a known liquid crystal projector. The TV camera (6) is mounted on the ceiling (4) via a direction adjustment device (7). The orientation adjustment device (7) is composed of an azimuth angle adjustment servo mechanism (first servo mechanism) (7a) for adjusting the angle (azimuth angle) in the horizontal plane about the vertical axis, and (7a) And a servo mechanism for adjusting the elevation angle (second servo mechanism) (7b) for adjusting the angle (elevation angle) in the vertical plane. The azimuth angle is adjusted by the first servo mechanism (7a) and the elevation angle is adjusted by the second servo mechanism (7b), so that the orientation of the television camera (6) can be changed. O

The indicating member (8) is used by a speaker or the like to indicate a two-dimensional position on the screen (2) and a three-dimensional position in the space of the room, switching of a measurement mode to be described later, various operation commands, and the like. The position measurement device (12) is an object to be measured by the position measurement device (12). The position measurement device (12) performs measurement mode switching information from the pointing member (8) based on the information. It is for selectively measuring the two-dimensional position on the screen (2) and the three-dimensional position in space indicated by the pointing member (8).

The control device (13) controls the direction adjustment device (7) and the TV camera (6) based on the operation command information from the pointing member (8) and the three-dimensional position information measured by the position measurement device (12). Control of image display device (10) based on operation command information from pointing member (8), two-dimensional position information measured by position measurement device (12), image signal from TV camera (6), etc. It is for doing. Although illustration is omitted, the control device (13) includes a microcomputer (not shown) and the like, and an appropriate external storage device and a printing device as necessary. An output device such as a device is provided. The control device (13) is set in advance with three-dimensional position information of the television camera (6) in the space. The control device (13) is functionally provided with image deformation means for performing image deformation described below.

Fig. 3 shows the details of the appearance of the pointing member (8), and Fig. 2 shows the details of its electrical configuration. The indicating member (8) is provided with a rod-shaped case (14) which is slightly bent at a portion closer to the base end than in the middle of the length, and linearly extends toward the base end and the front end portion with the bending force. ing. An omnidirectional microphone (hereinafter abbreviated as microphone) (15) is attached to the tip of the case (14). The microphone (15) is omnidirectional and has sufficient reception sensitivity to sound in the ultrasonic band of about 40 kHz, and is composed of, for example, an electret condenser microphone. This constitutes a receiver of a position detection device (12) described later. The mode selection button (16), upper button (Π), and lower button (18) are attached to the bent part of the case (14). A tip contact detection switch (abbreviated as tip switch) (19) is attached to the tip of the case (14). The mode selection button (16) is a self-holding switching switch that is switched between the on (closed) state and the off (open) state and is held in each state. The other buttons (16) ( Ii) (18) and the switch (19) are self-returning push-button switches that are turned on only during operation. The microphone (15), the button (16) (Π) (18) and the switch (19) are connected to the cable (20) and the cable (20) connected to the proximal end of the pointing member (8) as described in detail later. The control unit (1U is connected to the required location via the connector (21). The mode selection button (16) is used for the two-dimensional measurement mode (12) of the position measurement device (12) described later. 2D mode) and 3D measurement It is used to switch modes (abbreviated as 3D mode). The upper button (Π) and the lower button (18) are for performing various operation commands described later. The tip switch (19) is used to detect that the tip of the pointing member (8) has contacted the screen (2) when performing handwriting input described later on the screen (2). Things.

The position measurement device (12) includes the two-dimensional transmitter (3), three-dimensional transmitter (5) and microphone (15), as well as the mode switching device (22), the transmission device (23), and the reception device. Equipment (24) and processing equipment (25) are provided. The parts of the position measurement device (12) other than the transmitters (3) and (5) and the microphone (15) and the control device (13) are built in the control unit (11).

Each of the transmitters (3) (5) is composed of, for example, a piezoelectric ultrasonic transducer. The natural frequency wave of the first transmitter (3a) (5a) for 2D and 3D is 25 kHz, the natural vibration of the second transmitter (3b) (5b) for 2D and 3D The number wave is 40 kHz, the natural frequency wave of the third transmitter for 3D (5c) is 32 kHz.

The transmitter (23) intermittently and almost simultaneously transmits ultrasonic bursts having different frequencies from each two-dimensional transmitter (3) or each three-dimensional transmitter (5) according to the measurement mode described later. It is provided with three transmission circuits (26a) (26b) (26c) and a 50 Hz transmission control oscillation circuit (27). The transmission circuits are collectively referred to by reference numeral (26), and when it is necessary to distinguish them, they will be referred to as a first transmission circuit (26a), a second transmission circuit (2Gb), and a third transmission circuit (26c), respectively. The oscillation circuit (27) is for controlling the transmission interval of the ultrasonic burst, and transmits the transmission start pulse signal A every 2 O msec to each of the transmission circuits (26) and the receiving device (24). And output to the processing device (25). Each transmission circuit (26) is for outputting transmission signals Bl, B2, and B3 having a constant frequency for several cycles when the transmission start pulse signal A is input from the oscillation circuit (27). . Although not shown, each transmission circuit (26) is, for example, an oscillation circuit that constantly outputs a transmission pulse signal of a constant frequency, and a gate for a predetermined time when a transmission start pulse signal A is input. It has a gate circuit that opens and outputs several cycles of transmission pulse signals as transmission signals Bl to B3. Each transmitting circuit (26) outputs measurement start pulse signals CI, C2, and C3 in synchronization with the rise of the first pulse of the transmission signals B1 to B3, respectively. The frequencies of the transmission signals Bl to B3 are 25 kHz for the first transmitting circuit (26a), 40 kHz for the second transmitting circuit (26b), and 40 kHz for the third transmitting circuit (26c). 32 kHz <Actually, the frequency of the transmission signals B 1 to B 3 of each transmission circuit (26) is slightly higher than the natural frequency of the corresponding transmitter (3) (5). Has been detuned. That is, the frequencies of the actual transmission signals Bl to B3 are, for example, 25.2 kHz for the first transmitting circuit (26a) and 40.4 kHz for the second transmitting circuit (26b). The third transmitting circuit (26c) is set to 32.3 kHz. The levels of the transmission signals Bl to B3 of each transmission circuit (26) are controlled based on transmission level control signals D1, D2, and D3 from the processing device (25) described later. FIG. 8 shows an example of the transmission signal B 2.

The mode switching device (22) measures the two-dimensional position on the screen (2) based on the state of the mode selection button (16) of the pointing member (8) and the two-dimensional mode and the room. It is for switching to the three-dimensional mode for measuring the three-dimensional position in the space of the two-dimensional measurement. The first transmission circuit (26a) is connected to the first two-dimensional transmitter (3a). The first switch (28) and the second transmission circuit (26b) for switching to the 3D measurement state connected to the 3D first transmitter (5a) are connected to the 2D second transmitter (3b). ) Connected to the 2D measurement state and the 2D switch (29) for switching to the 3D measurement state connected to the 3D second transmitter (5b), and the 3rd transmission circuit (26c). The 3rd mode can be switched between the 2D measurement state (open state) disconnected from the 3D 3rd transmitter (3c) and the 3D measurement state (closed state) connected to the 3D 3rd transmitter (3c). An opening / closing switch (30) is provided. When the mode selection button (16) of the indicating member U) is switched to the two-dimensional mode, the switches (28) to (30) of the mode switching device (22) are in the two-dimensional measurement state. And a 25 kHz ultrasonic burst (first ultrasonic burst) from the first two-dimensional transmitter (3a) based on the transmission signal B 1 from the first transmission circuit (26a). Force A 40 kHz ultrasonic burst (second ultrasonic burst) is transmitted from the two-dimensional second transmitter (3 b) based on the transmission signal B 2 from the second transmission circuit (26b). Is done. Conversely, when the mode selection button (16) of the indicating member (8) is switched to the three-dimensional mode, each of the switches (28) to (30) of the mode switching device (22) is activated. The state is switched to the three-dimensional measurement state, and based on the transmission signal B1 from the first transmission circuit (26a), the first ultrasonic burst is transmitted from the first three-dimensional transmitter (5a) to the second transmission circuit (5a). The second ultrasonic burst is transmitted from the second three-dimensional transmitter (5b) based on the transmission signal B2 from the second transmission circuit 26b), and the three-dimensional burst is transmitted based on the transmission signal B3 from the third transmission circuit (26c). An ultrasonic burst of 32 kHz (third ultrasonic burst) is transmitted from the third transmitter for transmission (5c).

The receiving device (24) converts the reception signal E from the microphone (15) of the pointing member (8) into a band-pass filter having narrow-band characteristics having different center frequencies.

Three This is to detect the received signal for each transmitter for the ultrasonic burst from each transmitter (3) (5) through the filter (31a) (31b) (31c). Circuits (32a), (32b), and (32c). The receiving circuits are collectively referred to by reference numeral (32), and when it is necessary to distinguish them, they are referred to as a first receiving circuit (32a), a second receiving circuit (32b), and a third receiving circuit (32c), respectively. And Filters are also collectively referred to by reference numeral (31), and when they need to be distinguished, they are referred to as a first filter (3 la), a second filter (31b), and a third filter (31c), respectively. A reception signal from the microphone (15) is transmitted to each reception circuit (32) E. A transmission start pulse signal A from the transmission control oscillation circuit (27) and a measurement start pulse signal C 1 to a corresponding measurement start pulse signal from each transmission circuit (26) C 3 is input, and the count control signals F 1, F 2, and F 3 are output from the receiving circuits (32) to the processing device (25). The center frequency of the first filter (31a) is 25 kHz, and the first receiving circuit (32a) detects the received signal for each first transmitter for the first ultrasonic burst <second filter The center frequency in the evening (31b) is 40 kHz, and the second receiving circuit (32b) detects the second transmitter-specific received signal for the second ultrasonic burst. The center frequency of the third filter (31c) is 32 kHz, and the third receiving circuit (32c) detects the second transmitter-specific received signal for the second ultrasonic burst. The count control signals F1 to F3 from each receiving circuit (32) are used between the time when the corresponding measurement start pulse signals CI to C3 are input and the time when the corresponding received signal for each transmitter is detected. Is on, otherwise it is off.

The processing device (25) calculates the corresponding reception signal for each transmitter by the receiving device (24) from the transmission start time of the ultrasonic burst by each two-dimensional transmitter (3) or each three-dimensional transmitter (5). Until the detection time of

Four To determine the distance from each 2D transmitter (3) or each 3D transmitter (5) to the microphone (15) and the 2D or 3D position of the microphone (15) based on the elapsed time It is equipped with a counting device (33), a 1 MHz counting oscillation circuit (34), and an arithmetic device for position measurement (35). The counting device (Π) has three counters (36a), (36b) and (36). The counters are collectively referred to by the reference numeral (36), and when it is necessary to distinguish them, the first power counter is used. (36a), the second counter (36b) and the third counter (36c) The oscillation circuit (34) is a 1 MHz clock pulse for counting time. Is output to each counter (36), and the counter control signals F 1 to F 3 from the corresponding receiving circuit (32) and the arithmetic unit (35) are output to each counter (36). The reset signal G from the controller is input, and the count values HI, H2, and H3 of each counter (36) are input to the arithmetic unit (35). The first ultrasonic burst is transmitted by the first transmitter for 3D or 3D transmission (3a) (5a), and then the corresponding received signal for each first transmitter is transmitted to the first receiver circuit (32 The second force counter (36b) is used to count the elapsed time until detection by a), and the second force counter (36b) is used by the second or three-dimensional second transmitter (3b) (5b). (2) For counting the elapsed time from the start of transmission of the ultrasonic burst to the detection of the corresponding received signal by the second transmitter by the second receiving circuit (32b). The third counter (36c) starts transmission of the third ultrasonic burst by the three-dimensional third transmitter (5c), and then transmits the corresponding third-transmitter-specific received signal to the third receiver circuit (36c). Each counter (36) is reset by a reset signal G from the arithmetic unit (35), and counts the elapsed time until detection by 32c). While the corresponding count control signals F1 to F3 are on, the pulse from the oscillation circuit (34) is counted to count the time and the count value when the count is stopped. H1 to H3 are held.

The arithmetic unit (35) determines the distance from each two-dimensional transmitter (3) to the microphone (15) or each three-dimensional transmitter (3) based on the count values HI to H3 of each counter (36). This is for determining the distance from the microphone (15) to the microphone (15), and for determining the two-dimensional or three-dimensional position of the microphone (15) based on these distances. (Computer). In addition, the arithmetic unit (35) functionally includes A 0 C (automatic output level control) means for controlling the level of the transmission signal of the corresponding transmission circuit (26) according to the reception level of the reception signal for each transmitter. ing. The arithmetic unit (35) contains the ultrasonic wave propagation velocity, the position coordinate information of the two 2D transmitters (3) on the 2D coordinates on the screen (2), and the 3D coordinates in space. Information necessary for position measurement, such as the position coordinate information of the three three-dimensional transmitters (5), is set and stored. <A temperature sensor is installed at an appropriate location on the presentation device. However, it is also possible to correct the set value of the ultrasonic wave propagation speed according to the temperature change. Each time the transmission start pulse signal A is input from the transmission control oscillation circuit (27), the arithmetic unit (35) reads the count values H1 to H3 of each counter (36) and stores them. The reset signal G is output to each counter (36). Until the next transmission start pulse signal A is input, each two-dimensional transmitter (3) or each two-dimensional transmitter (3) is used based on the previously stored count values HI to H3 of each counter (36). Distance from 3D transmitter (5) to microphone (15) and 2D or 3D position of microphone (15)

6 Calculate the position. Further, the arithmetic unit (35) uses the AOC means to transmit the transmission signals B 1 to B 1 to the transmitter (3) (5) based on the distance from each transmitter (3) (5) to the microphone (15). Calculates the transmission level value of B3 and sends it to the corresponding transmission circuit (26). Output as 3. The arithmetic unit (35) receives buttons (16) to () of the indicating member (8) and switch signals from the switch (19), and inputs the switch signal information and the measurement mode. Selection information, coordinate information of the measured two-dimensional position and three-dimensional position, and the like are output from the arithmetic unit (35) to the control unit (13).

With the above-described configuration, the position measuring device (12) is configured such that each time the transmission start pulse signal A is output from the transmission control oscillation circuit (27), the two-dimensional microphone (15) according to the measurement mode. Measure position or 3D position. Next, the position measurement operation by the position measurement device (12) will be described in detail for each measurement mode.

When the transmission start pulse signal A is output from the transmission control oscillation circuit (27) when the two-dimensional mode is selected, first, the first and second counters (36a) are operated by the arithmetic unit (35). After reading the count values HI and H2 of (36b) and storing them in memory, etc., the reset signal G is output from the arithmetic unit (35), and each counter (36a ) (36b) is reset, and at the same time or slightly later, the first and second ultrasonic bursts are transmitted from the two two-dimensional transmitters (3), respectively. Simultaneously with the start of transmission of each ultrasonic burst, the first and second transmitting circuits (26a) and (26b) transmit the measurement start pulse signals C 1 and C 2 is output, which turns on the count control signals F 1 and F 2, and the first and second counters (36 a) and (36 b) start counting. . Then, the next transmission start pulse signal A is output. In the meantime, the arithmetic circuit (35) calculates the two-dimensional position coordinates of the microphone (15) and outputs the transmission level control signals D 1 and D 2 as described later. After the transmission of the first and second ultrasonic bursts is started, when the first ultrasonic burst transmitted from the two-dimensional first transmitter (3a) is received by the microphone (15), a response is made to this. The first receiver-specific received signal is detected by the first receiver circuit (32a), the count control signal F1 is turned off, and the first counter (36a) stops counting. At this time, the count value HI held at the first counter (36) is the elapsed time from the transmission start time of the first ultrasonic burst to the detection time of the first transmitter-specific received signal corresponding thereto. That is, it corresponds to the time required for the ultrasonic wave to propagate from the two-dimensional first transmitter (3a) to the microphone (15). 2 When the ultrasonic burst is received by the microphone (15), a second transmitter-specific received signal corresponding thereto is detected by the second receiving circuit (32b), and the count control signal F 2 is received. The counter is turned off, the second counter (36b) stops counting, and the count value H2 held in the second counter (36b) is determined by the transmission of the second ultrasonic burst. Elapsed time from the start time to the detection time of the second transmitter-specific received signal, that is, the 2D second transmission This is equivalent to the time required for the ultrasonic wave to propagate from the transmitter (3b) to the microphone (15) When the next transmission start pulse signal A is output, the arithmetic unit ( According to 35), the count values HI and H2 are read and stored, and the reset signal G is output.The transmission circuit (26a) (26b). (32b) and counters (36a) and (36b) perform the same operation as described above, and at the same time, in the arithmetic unit (35), based on the previously stored count values H 1 and H 2. Then, the distance from the two two-dimensional transmitters (3) to the microphone (15) is calculated, and based on these distances, the screen (2) of the microphone (15) is calculated. The above two-dimensional position coordinates are calculated. As described above, the count value HI of the first counter (36a) corresponds to the time required for the ultrasonic wave to propagate from the first two-dimensional transmitter (3a) to the microphone (15). Therefore, the distance from the first two-dimensional transmitter (3a) to the microphone (15) can be calculated from this time and the propagation speed of the ultrasonic wave. Similarly, the distance from the second two-dimensional transmitter (3b) to the microphone (15) can be calculated from the count value H2 of the second counter (36b) and the propagation speed of the ultrasonic wave. Then, based on these distances and the two-dimensional position coordinate information of the two two-dimensional transmitters (3) set in the arithmetic unit (35), the two-dimensional position coordinates of the microphone (15) are calculated. can do. On the other hand, in the A 0 C means of the arithmetic unit (35), the transmission level to the first transmission circuit (26a) is calculated based on the calculated value of the distance from the first two-dimensional transmitter (3a) to the microphone (15). A value is obtained, and this is output to the first transmission circuit (26a) as a transmission level control signal D1. This transmission level value is preferably obtained by selecting a preset step-like value so as to increase as the calculated value of the distance increases. Next, when the transmission start pulse signal A is output and the first transmission circuit (26a) outputs the transmission signal B1, the transmission signal B1 is output based on the transmission level control signal D1. Level is adjusted. That is, the level of the transmission signal B 1 is adjusted based on the calculated value of the distance to the ultrasonic burst two times before. As a result, even if the distance from the transmitter (3a) to the microphone (15) changes, the reception level of the first transmitter-specific reception signal received by the reception circuit (32a) falls within a certain range. To

9 Become. Similarly, a transmission level value for the second transmission circuit (26b) is obtained based on the calculated value of the distance from the second two-dimensional transmitter (3b) to the microphone (15). The signal is output to the second transmitting circuit (26b) as D 2, the transmission start pulse signal A is output next, and the transmission signal B 2 is output from the second transmitting circuit (26b). The level of the transmission signal B 2 is adjusted based on the transmission level control signal D 2. Then, by repeating the above operation, each time the transmission start pulse signal A is output, the two-dimensional position of the microphone (15) is measured.

Even when the three-dimensional mode is selected, when the transmission start pulse signal A is output from the measurement control oscillation circuit (27), first, the arithmetic unit (35) uses the three counters (36). After reading and storing the count values H1 to H3, the reset signal G is output from the arithmetic unit (35), and each counter (36) is reset. Later, the first, second and third ultrasonic bursts are transmitted from the three three-dimensional transmitters (5), respectively. At the same time as the transmission of each ultrasonic burst, the measurement start pulse signals C 1, C 2, and C 3 are output from the three transmission circuits (26) to the three reception circuits (Π), respectively. The control signals F1, F2 and F3 are turned on, and the three counters (36) start counting. Then, before the next transmission start pulse signal A is output, the arithmetic unit (35) calculates the three-dimensional position coordinates of the mig (15) and the transmission level control signal D 1, as described later. D 2 and D 3 are output. After the start of transmission of each ultrasonic burst, the first ultrasonic burst transmitted from the first three-dimensional transmitter (5a) is received by the microphone (15). The signal is detected by the first receiving circuit (32a) and its power is The count control signal F1 is turned off, and the first counter (36a) stops the power count. Similarly, when the second ultrasonic burst transmitted from the second three-dimensional transmitter (5b) is received by the microphone (15), the second counter (36b) stops counting, and The third counter (36c) stops counting when the third ultrasonic burst transmitted from the three-dimensional third transmitter (5) is received by the microphone (15). In this case, In addition, the count value HI of the first counter (36a) is equal to the time required for the ultrasonic wave to propagate from the first three-dimensional transmitter (5a) to the microphone (15). The count value H2 of the counter (36b) is calculated by the time required for the ultrasonic wave to propagate from the second three-dimensional transmitter (5b) to the microphone (15), and the count of the third counter (36c). The value H3 corresponds to the time required for the ultrasonic wave to propagate from the third-dimensional third transmitter (5c) to the microphone (15) The next transmission start pulse signal A is output When, Similarly to the above, the arithmetic unit (35) reads and stores the count values H1, H2, and H3, and outputs the reset signal G. Then, the transmission circuit (26), the transmitter (5) The same operation as described above is performed in the circuit (32) and the counter (36) At the same time, in the arithmetic unit (35), based on the previously stored count values HI, H2, and H3, As in the case of the two-dimensional mode, the distances from the three three-dimensional transmitters (5) to the microphone (15) are calculated respectively, and further, these distances and the calculation device (35) are calculated. The three-dimensional position coordinates of the microphone (15) are calculated based on the three-dimensional position coordinate information of the three set three-dimensional transmitters (5). In the C means, based on the calculated value of the distance from the three transmitters (5) to the microphone (15), as in the case of the two-dimensional measurement mode, Transmission level values for the three transmission circuits (26) are determined, and these are used as transmission level control signals. The signals are output to the corresponding transmitting circuits (26) as signals Dl, D2, and D3. By repeating the above operation, the three-dimensional position of the microphone (15) is measured each time the transmission start pulse signal A is output.

In the above presentation device, as described above, the two-dimensional position or the three-dimensional position is always measured by the position measuring device (12). That is, while the mode selection button (16) of the indicating member (8) is switched to the two-dimensional mode, the two-dimensional position is measured and the two-dimensional position information is transmitted to the control device (U). ), And while the mode selection button (16) is switched to the 3D mode, the 3D position is measured and the 3D position information is sent to the controller (13). Sent. Then, based on the position information, the switch signal information from the indicating member (8), and the like, the control device (13) uses the direction adjustment device (7), the television camera (6), and the image display device. The image displayed on the screen (2) is controlled by controlling the device (10).

For example, if the speaker moves the pointing member (8) to an arbitrary position on the screen (2) with the mode selection button (16) switched to the two-dimensional mode, The two-dimensional position of the microphone (15) at the tip of the pointing member (8) on the screen (2) is measured. By combining such two-dimensional position measurement with various operation commands from the pointing member (8) using the upper button (11) and the lower button (), for example, the screen (2 ) Controls such as switching the upper display, and selection of the work menu displayed on the screen (2). Also, by pressing the tip switch (19) of the indicating member (8) against the screen (2) to turn it on, the hand switch mode is set and the tip switch (19) is set to the handwriting mode. By pushing the switch (19) against the screen (2) and moving it, handwriting input is performed by the pointing member (8), and the information input by handwriting is displayed in this way. Or, for example, by pressing the lower button (1 8) (while keeping the button on) and moving the indicating member (8), handwriting input can be performed with t) o

When the speaker moves the indicating member (8) to an arbitrary position in the space with the mode selection button (16) switched to the three-dimensional mode side, the instruction at that time is given. The three-dimensional position of the tip of the member (8) is measured. Then, by combining such three-dimensional position measurement with various operation commands from the pointing member (8) using the upper button (Π) and the lower button (18), The TV camera (6) captures objects such as materials and displays the images. For example, when the tip of the pointing member (8) is brought close to an object such as a document placed at an arbitrary position such as on a desk (9) and an imaging command is issued, the control device (13) causes the control device (13) to perform the imaging command. The position of the tip of the pointing member (8), that is, the three-dimensional position information of the object is stored. Based on this position information and the position information of the television camera (6), the azimuth of the orientation adjustment device (7) is stored. The angle of the camera and the elevation angle are controlled, the TV camera (6) is pointed at the object, the focus of the TV camera (6) is adjusted, the object is imaged, and the TV camera is imaged. Based on the image signal from (6), the captured image of the object can be displayed on the screen (2).

When displaying an image captured by a TV camera (6) on a screen (2), image deformation such as moving, enlarging / reducing, rotating, projective transformation, etc. is performed to make it easier to see, or stored in advance. Doing In some cases, it is required to combine with another image or add comments etc. by handwriting input.However, it is necessary to select the measurement mode from the pointing member U) and respond to various operation commands. Based on this, the above-described operation can be performed by the image deforming means of the control device.

Next, with reference to FIGS. 16 and 17, a detailed description will be given of an example of the operation of the indicating member (8) and the image deformation processing in the case of enlargement / reduction, rotation, and projective transformation in the image deformation. I do.

(A), (b) and) in FIG. 16 are diagrams for explaining the operation method of the pointing member (8). In each figure, the imaging range of the television camera (6) is indicated by a symbol T. ing. The position in the space is represented by three-dimensional rectangular coordinates based on the X, Y, and Z axes. In this case, the X and Y axes are horizontal and the Z axis is vertical.

When instructing image deformation, first, as shown in Fig. 16 (a), the center point P of the operation is set within the imaging range T of the television camera (6). This operation is performed by bringing the tip of the pointing member (8) (the portion of the microphone (15)) into the imaging range T and double-clicking the lower button (18). If the lower button (18) is double-clicked while the tip of the pointing member (8) is within the imaging range T, the position of the tip of the pointing member (8) measured at that time is changed. Set as center point P. When the setting of the center point P of the operation is completed, the reference vector VQ is set as shown in Fig. 16 (b). <This operation moves the tip of the pointing member (8) to a desired position in the space. After moving, this is done by clicking the lower button (18). After setting the operation center point P, if the first click of the lower button (18) is performed, measurement is performed from the operation center point P at that time. The vector up to the position of the tip of the pointing member) is determined, and this is set as the reference vector VQ. After setting the reference vector V o, the comparison vector V a is set as shown in Fig. 16 (c). This operation is also performed by moving the tip of the pointing member (8) to a desired position in the space and then clicking the lower button (18). This operation can be repeated many times. After the center point P of the operation is set, when the lower button (18) is clicked for the second time or later, the tip of the pointing member (8) measured at that time from the center point P of the operation The vector up to the position is obtained, and this is set as the comparison vector Va at that time. Then, each time the comparison vector Va is set, the type of image deformation is determined based on the comparison vector Va, and the determined image processing is executed.

The decision on image processing is made as follows by comparing the comparison vector V a with the reference vector V o. That is, when the comparison vector V a is set, first, the rotation angle 6 »of the comparison vector V o, the change rate AL of the length of the comparison vector V a, and the Z of the comparison vector V a The coordinate change rate ΔZ is obtained. The rotation angle 0 is represented by the angle formed by the projection of the comparison vector V a onto the XY plane with respect to the projection of the reference vector V o onto the XY plane. The rate of change of length AL is expressed by the ratio (L ao) of the length L a of the comparison vector V a to the length L o of the reference vector V o. The rate of change of the Z coordinate Δ Z is the Z coordinate value Z a of the tip of the comparison vector V a (the end opposite to the center point P of the operation) and the Z coordinate value 先端 of the tip of the reference vector V o. It is represented by the ratio ((Za-Z0) / L0) of the difference between ο (Za — Z0) and the length Lc of the reference vector Vo. These values are well known It can be obtained using a calculation formula.

Next, the three quantities of rotation angle, rate of change of length ΔL and rate of change of Z coordinate △ Z are compared with appropriate weights, and when the rotation angle is most dominant, the rotation of the image is When the rate of change ΔL is also the most dominant, the image is scaled up and down.

(A), (b) and (c) in Fig. 17 show the setting operation of the center point P, the reference vector VG and the comparison vector V a of the operation by the indicating member (8), and the corresponding operations. FIG. 6 is a diagram showing a relationship with image deformation to be performed. The left side of each figure in FIG. 17 shows the operation of the pointing member (8), (a) and (b) are plan views of the portion of the imaging range T, and (c) is a perspective view of the same portion. ing. The right side of each figure in Fig. 17 shows the state of image deformation on the screen (2), all of which are views of the screen (2) viewed from the front. In the case of FIG. 17, the reference vector V 0 is set so as to be substantially parallel to the Y axis.

When instructing image rotation, for example, the comparison vector V a is set as shown in Fig. 17 (a). In this case, the comparison vector V a is set so that the length is not substantially different from the reference vector V G and is substantially horizontal. For this reason, the rotation angle is larger than the rate of change ΔL of the length and the rate of change ΔZ of the Z coordinate, the image is rotated, and the image on the screen (2) is indicated by a broken line. The state changes from the state shown to the state shown by the solid line. In this case, the direction and degree of rotation of the image are determined based on the direction and magnitude of the rotation angle 0.

When instructing enlargement / reduction of an image, for example, the comparison vector Va is set as shown in Fig. 17 (b). In this case, compare The vector Va is set in almost the same direction as the reference vector VG. For this reason, the rate of change of the length is larger than the rate of change ΔZ of the rotation angle S and the Z coordinate, and the image is enlarged and reduced. In the case of the figure, since the comparison vector Va is longer than the reference vector VQ, and therefore, the length change rate ΔL is larger than 1, the image is enlarged and the screen ( 2) The upper image changes from the state shown by the broken line to the state shown by the solid line. When the comparison vector V a is shorter than the reference vector VG, the length change rate ΔL becomes smaller than 1, and the image is reduced. In this case, the degree of enlargement / reduction of the image is determined based on the length change rate.

When instructing projective transformation of an image, for example, the comparison vector Va is set as shown in Fig. 17 (c). In this case, the comparison vector V a is set so that its length is not substantially different from the reference vector VG, and is approximately in the vertical plane including the reference vector VQ. Therefore, the rate of change Δ Z of the Z coordinate becomes larger than the rotation angle 0 and the rate of change AL of the length, and the projective transformation of the image is performed. The image on the screen (2) is indicated by a broken line. The state changes from the state shown to the state shown by the solid line. In this case, the direction and degree of the projective transformation of the image are determined based on the sign (direction) and the magnitude of the rate of change Δ Δ of the Z coordinate.

If the television camera is only aimed at the object to be imaged, a light source may be attached to the tip of the indicating member, and the light source may be used to capture the image of the television camera, when the light source emits light, in addition to the method described in the above embodiment. One possible method is to control the direction of the TV camera so that it is in the center of the range, and then align the pin with the light source. However, this method cannot accurately measure the three-dimensional position of the light source Therefore, it is not possible to instruct an image deformation using the above-described instruction member. Also, the TV camera cannot be pointed in a direction that is not within the field of view of the TV camera.

One example of the configuration of the second receiving circuit (32b) is shown in FIG. 4. The receiving circuit (26b) includes an amplifying circuit (37b), a band filter (31b) having a narrow band characteristic, Half-wave rectifier circuit (38b), stepped envelope (envelope waveform) generator (39b), shaping circuit (40b), comparator Ulb), FZF (flip-flop) (42 b) and ATLC circuit (automatic threshold adjustment circuit) (43b).

In the second receiving circuit (32b), the received signal E from the microphone (15) is amplified by the amplifier circuit (37b) and input to the filter (311)). At the filter (31b), the second transmitter-specific received signal I (see Fig. 9 (a)) for the second ultrasonic burst from the corresponding second transmitter (3b) (5b) is extracted. This is input to the half-wave rectifier circuit (38b). In the half-wave rectification circuit (38b), the received signal I for each second transmitter is half-wave rectified, and in the envelope generation circuit (39b), the half-wave rectified wave of the signal I is converted into a stepped envelope J (Fig. 11). Is generated. The envelope generation circuit (39b) is well known as an AM wave detection circuit, and includes a capacitor (44) and a resistor (45). In a normal detection circuit, a smooth envelope connecting the peaks of the half-wave rectified wave is generated. In this generation circuit (39b), the CR values of the capacitor (44) and the resistor (45) are usually It is smaller so that the envelope rises in steps. In the shaping circuit (40b). After the stepped envelope J is amplified by the amplifier circuit (46), the low-frequency component is removed by the high-pass filter (47), and the stepped envelope with a large difference between the steps of the stairs. K (see Figure 12) is generated This is input to one input terminal of the comparator lb). The threshold value L from the ATLC circuit (43b) is input to the other input terminal of the comparator (41b), and the output signal of the comparator Ulb) is input to FZF U2b). The comparator (41b) compares the stepped envelope with the threshold value L (see Fig. 13), and while the envelope is below the threshold value L, the output signal of the comparator (41b) is off (L0w). When the envelope K exceeds the threshold L, the output signal of the comparator Ulb) is turned on (High level).

The AT LC circuit (43b) is a well-known type that adjusts the threshold value L in accordance with the reception level of the signal I in order to improve the measurement accuracy. The first analog switch (48), It includes a first and a second peak hold circuit U9) (50), a second analog switch (51) -scale conversion circuit (52), and a switch control circuit (53). The transmission start pulse signal A from the transmission control oscillation circuit (27) is input to the switch control circuit (53). Each time the transmission start pulse signal A is input, the switch control circuit (53) outputs The two switches (48) and (51) are interlocked to switch between the first state and the second state. In the first state, the first switch U8) is switched to the second peak hold circuit (50), and the envelope J is input to the second peak hold circuit (50) and The second switch (51) is switched to the first peak hold circuit (49). The output of the first peak hold circuit (49) is input to the scale conversion circuit (52). Conversely, in the second state, the first switch U8) is switched to the first peak hold circuit (49), and the envelope J is switched to the first peak hold circuit U9). And the second switch (51) is connected to the second peak hold circuit (50). The output of the second peak hold circuit (50) is input to the scale conversion circuit (52). The scale conversion circuit (52) is adapted to respond to the peak value of the previous envelope J held by each of the peak hold circuits (49) (50) input via the second switch (51). It adjusts the size of the threshold value L. The threshold value L is adjusted, for example, so as to be a fixed ratio (for example, 1 Z 5) with respect to the previous peak value of the envelope J. When the transmission start pulse signal A is input to the switch control circuit (53) and the switch U8) (51) is switched to the first state, the reception is performed from the microphone (15) after this. When the signal E is input, the envelope J is input to the second peak hold circuit (50) via the first switch (48), and the peak value is held. At this time. The first peak hold circuit (49) holds the peak value of the envelope J input after the previous input of the transmission start pulse signal A, and this is the second switch. It is input to the scale conversion circuit (52) via (51), and the threshold value L is adjusted based on this peak value. When the next transmission start pulse signal A is input to the switch control circuit (53) and the switches (48) and (51) are switched to the second state, the microphone (15) ), The received signal E is input, the envelope J is input to the first peak hold circuit (49) via the first switch (48), and the peak value is held. At this time, the peak value of the envelope J input after the previous input of the transmission start pulse signal A is held in the second peak hold circuit (50) as described above. The signal is input to the scale conversion circuit (52) via the switch (51) of 2, and the threshold value L is adjusted based on this peak value. Each time the transmission start pulse signal A is input, By repeating this operation, the current threshold value L is adjusted according to the peak value of the envelope J input after the previous transmission start pulse signal A was input.

The F / F (42b) is for outputting the count control signal F2 to the second counter (36b), and the measurement start pulse signal C2 from the second transmission circuit (26b) is FZF ( 42b). The count control signal F 2, which is the output of the F / F (42b), turns on when the measurement start pulse signal C 2 is input, and turns on when the output signal of the comparator (41b) turns on. It turns off and then keeps on until the measurement start pulse signal C 2 is input.

In the second receiving circuit (32b), when the transmission start pulse signal A is input, the states of the switches (48) and (51) of the ATLC circuit (43b) are switched, and thereby the scale conversion circuit (52) The threshold L adjusted based on the previous peak value of the envelope J held by the connected peak hold circuit (49) (50) is input to the comparator (b). Thereafter, when the transmission signal B2 is output from the second transmission circuit (26b) and the measurement start pulse signal C2 is output, the count control signal F2 from the FZF (42b) is turned on. Then, when the stepped envelope K for the second transmitter-specific received signal I extracted by the filter (31b) exceeds the threshold L, this is detected by the comparator (41b), and the comparator (41b) detects this. The output signal of 41b) turns on, and the count control signal F 2 from F ZF (42b) turns off. That is, as described above, the count control signal F 2 is turned on from the input of the measurement start pulse signal C 2 to the detection of the second transmitter-specific received signal I.

The configuration of the second filter (31b) in the second receiving circuit (32b) One example is shown in FIG. The filter (31b) includes a pair of piezoelectric ultrasonic transducers (55) and (56) disposed opposite to each other in a cylindrical case (54). Each transducer (55) (56) consists of an elastic body (55a) (56a), a piezoelectric ceramic (55b) (56b), a metal plate (55c) (56c), and a resonator (55d). ) (56d), the elastic members (55a) and (56a) at both ends of the case (54) so that the resonators (55d) and (56d) face each other. It is fixed to the support members (57) (58) fixed to the part. The input-side transducer (55) is connected to the input terminals (59a) and (59b), and the input terminal (59b) is connected to the output terminal of the amplifier circuit (b). The transducer (56) on the output side is connected to the output terminals (Ha) and (60b), and the output terminals (60a and Qb) are connected to the input terminals of the half-wave rectifier circuit (38b). The natural frequency of the two transducers (55) (56) is 40 kHz, and the spacing between the resonators (55 d) and (56 d) is the corresponding ultrasonic (40 kHz) ) Is set to about one wavelength. The center frequency of this finalizer (31b) is 40 kHz, and its cutoff characteristics (discriminability) are shown by the curve (b) in Fig. 6. Note that the degree of detuning of the transmission signal B 2 of the transmission circuit (26b) with respect to the center frequency of the filter (31b) is determined based on the cutoff characteristics of the filter (31b).

The configuration of the first and third receiving circuits (a) and (32c) is almost the same as that of the second receiving circuit (32b). In the first receiving circuit (32a), the center frequency of the first filter (31a) is 25 kHz, and the FZF for outputting the count control signal F1 has the first frequency. The measurement start pulse signal C 1 from the transmission circuit (26a) is input. In the third receiving circuit (32c), the center of the third filter (31c). The frequency is 32 kHz, and the count control signal F 3 is output. The measurement start pulse signal C3 from the third transmission circuit (26c) is input to the F / F for the measurement. In FIG. 6, the cutoff characteristic of the first filter (31a) is indicated by a symbol (a), and that of the third filter (31c) is indicated by a symbol (c).

Conventionally, when performing two-dimensional or three-dimensional position measurement with the above-described position measurement device, the frequency of ultrasonic waves transmitted from a plurality of transmitters is set to be the same. However, in this case, if the ultrasonic waves are transmitted from each transmitter at the same time, it is not possible to distinguish which transmitter the ultrasonic wave received by the receiver is from, so the transmission of the ultrasonic waves from each transmitter and The distance was measured in a time-sharing manner. When measuring a two-dimensional position on a relatively small display screen, the number of transmitters is two and the propagation distance of the ultrasonic wave, that is, the propagation time, is short, so the distance from each transmitter must be measured. Even when time division is performed, the measurement cycle can be set to a sufficiently short value, for example, 1 O msec or less. However, when measuring a three-dimensional position in a relatively large space, the number of transmitters is three, and the propagation time of ultrasonic waves is long, so the distance from each transmitter is measured in a time-division manner. In this case, the measurement cycle cannot be shortened sufficiently. In the case of normal position measurement, it is not preferable that the measurement period be longer than 20 msec. For example, consider the measurement of a three-dimensional position within a space of about 3 m on one side.For a single transmitter, it takes 9 msec for an ultrasonic wave to propagate a distance of 3 m, and 3 With only one transmitter, it takes 27 msec for the propagation of ultrasonic waves alone, so the measurement cycle cannot be reduced to less than 20 msec.

In contrast, the position measuring device (12) transmits ultrasonic waves having different frequencies from the transmitters (3) and (5) almost simultaneously. Since the distance measurement from each transmitter (3) (5) to the microphone (15) is performed almost simultaneously, the measurement cycle can be shortened as compared with the case where distance measurement is performed in a time-division manner.

When three-dimensional position measurement is performed using ultrasonic waves, strong directivity of ultrasonic waves is not preferable. However, the directivity of the ultrasonic wave increases as the frequency increases, and the frequency of the ultrasonic wave that can be used for position measurement in a three-dimensional space is about 40 kHz or less. Also, if the frequency is too low, it will be close to the audible band, causing harsh noise and being affected by noise.Therefore, it is necessary to increase the frequency to about 25 kHz or more. Become. Thus, the ultrasonic frequencies that can actually be used by the three transmitters are relatively close, for example, 40, 32, and 25 kHz. When using ultrasonic waves of such close frequencies, it is difficult to completely separate the ultrasonic waves of each frequency with a normal band filter, and it is affected by other frequencies and external noise. Therefore, there is a problem that measurement accuracy is reduced. Therefore, it is difficult to perform highly accurate position measurement in a relatively short space within a relatively large space.

In contrast, in the position measuring device (12), the received signal E of the microphone (15) is passed through a plurality of band filters (36) having different narrow-band characteristics and having different center frequencies. Transmitter (3) Since the received signal I for each transmitter for the ultrasonic wave from (5) is detected individually, even if an ultrasonic wave of close frequency is used, other ultrasonic waves or extraneous noise can be detected. The measurement is not affected by noise, and highly accurate measurement is possible. Furthermore, since each filter (36) has the above-described configuration, it has excellent blocking characteristics, and is further less affected by other ultrasonic waves or extraneous noise. High-precision measurement becomes possible.

Further, in the position measuring device (12), the processing device (25) includes AOC means, and the reception level is changed even when the position of the microphone (15) (distance from the transmitters (3) and (5)) changes. Since the levels of the transmission signals B1 to B3 are controlled based on the reception level so that they fall within a certain range, the filter (36) itself has excellent blocking characteristics. In addition, it has excellent cut-off between operating frequencies (SZN ratio).

The ultrasonic reception level is inversely proportional to the distance from the sound source. Therefore, assuming that the transmission level of the ultrasonic burst from each transmitter (3) (5) is always constant, if the distance from the corresponding transmitter (3) (5) changes, the reception level Changes. Also, when the position of the microphone (15) changes, a difference occurs between the reception levels of the ultrasonic bursts, and the difference increases as the measurement range in the space increases. Actually, the difference between the reception levels is further increased due to the influence of the reflected wave and the angle between the transmission surface of the transmitters (3) and (5) and the reception surface of the microphone (15). For this reason, the filter (36) is required to have the cutoff characteristics shown in Fig. 7. That is, an attenuation rate of 1 Z 100 000 (−80 dB) or less is required near each other. In contrast, in the case of the above embodiment, the transmission level is controlled by the AOC means so that the reception level for each ultrasonic burst falls within a certain range. The breaking characteristics are as shown in Fig. 6 above. That is, the attenuation rate near other frequencies is better at 1 Z500 or less. However, it is difficult to realize the cutoff characteristics as shown in Fig. 6 with a conventional band filter using an electronic circuit, and the filter (36) can be realized with the above configuration. . However, in applications where a long measurement cycle is acceptable, multiple transmitters may transmit ultrasonic waves of the same frequency, and the distance from each transmitter may be measured in a time-division manner. In order to accurately measure the distance from the transmitter to the receiver (microphone), the position measurement device described above corrects the transmission start time of the ultrasonic burst and the detection time of the received signal corresponding thereto. It needs to be determined. The transmission start time of the ultrasonic burst can be accurately determined in synchronization with the rise of the first pulse of the transmission signal. The envelope of the transmitted signal is a square wave, as shown in Fig. 8. The envelope of the received signal, as shown in Fig. 9 (b), is affected by the band-pass characteristics of the signal transmission path. It rises obliquely. Therefore, it is difficult to accurately determine the detection time of the received signal. Conventionally, detection of a received signal in a receiving circuit is performed as follows. That is, first, the received signal is half-wave rectified, and the envelope of this half-wave rectified wave is taken. This envelope is a smooth one that connects the peaks of the half-wave rectified wave, as shown in Figs. Then, this envelope is compared with a predetermined threshold value, and when the threshold value is exceeded, it is determined that a received signal has been detected.

However, the conventional measurement methods described above have the following problems.

First, as explained earlier, the level of the received signal varies with the distance from the transmitter. If the receiving circuit is not provided with an ATLC circuit, the received signal is always compared with a fixed threshold. Therefore, as shown in Fig. 14, when the reception level of the received signal changes, detection is performed. A difference occurs between the points, and the difference in the time axis direction becomes a measurement error. Therefore, the receiving circuit An ATLC circuit is provided to adjust the threshold value based on the previous peak value of the received signal so that the ratio of the threshold value to the peak value of the received signal becomes constant. However, the ATLC circuit uses the peak value of the previous received signal as the estimated value of the peak value of the current received signal, so strictly speaking, the peak value of the previous received signal and the peak value of the current received signal Therefore, the ratio of the threshold value to the peak value of the received signal is not constant. As shown in Fig. 15, the time-axis component of this variation becomes the measurement error. This measurement error depends on the slope of the envelope. However, since the slope of the conventional smooth envelope is gentle, the measurement error due to the variation in the threshold value increases.

On the other hand, in the position measuring device (12), the level of the transmission signal is controlled by the AOC means so that the reception level of the reception signal is within a certain range. Measurement errors due to level fluctuations are reduced.

In the position measuring device (12), the receiving circuit (32) has an ATLC circuit (43b), and in addition to using a stepped envelope for detecting a received signal, The shape of the envelope is formed by the shaping circuit UOb), and the transmission signal of the transmitting circuit (26) is determined by the natural frequency of the transmitter (3) (5) and the center frequency of the filter (36). By detuning the frequencies B1 to B3 upward, the measurement accuracy is improved compared to the conventional one.

As is clear from Fig. 11, when a staircase-shaped envelope is used, the rising slope of each step of the staircase is steeper than that of a conventional smooth envelope. Then, when detecting the received signal by comparing the envelope with the threshold value. The measurement error is determined by the envelope of the envelope. Thus, for a stepped envelope, the measurement error is determined by the rising slope of each step of the step. Therefore, when the step-shaped envelope is used, the width of the measurement error is small, and the wavelength of the carrier is about 1 Z8. In the case of 25 kHz ultrasonic waves, the carrier wave length is 14 mm at room temperature, so the measurement error is about 2 mm (± l mm) at the maximum. In the case of the above embodiment, the stepped envelope is further formed to increase the difference between the steps of the steps as shown in FIG. 13, so that the width of the measurement error is further increased. Become smaller. If the frequency of the transmitted signal is not detuned with respect to the transmitter and filter frequencies, the received signal will be as shown in Fig. 9 (b), and the smooth envelope of the half-wave rectified wave will be as shown in Fig. 10. It becomes as shown by the solid line (b). On the other hand, if the frequency of the transmitted signal is detuned upward with respect to the transmitter and filter frequencies, the received signal will be as shown in Fig. 9 (a). The result is shown by the broken line (a) at 0. As is clear from FIGS. 9 and 10, when the transmitted signal is detuned, the waveform of the received signal is distorted, but the slope of the envelope becomes larger than in the case where no detuning is performed. Therefore, even when a stepped envelope is used, the rising slope of each step of the staircase becomes larger than when no detuning is performed, and the width of the measurement error is further reduced. In this case, since it is only necessary to determine the point at which the received signal is detected, there is no need to faithfully reproduce the received signal with respect to the transmitted signal, and there is no problem even if the received signal is distorted due to detuning.

In a conventional presentation device, a TV camera When capturing images of speakers and materials, and displaying the images on the screen, a fixed method of fixing the TV camera and capturing the materials that come within the field of view, Adjust the direction of the TV camera, register several possible positions in advance, and enter a registration number to turn the TV camera in that direction. A sound control method that automatically turns the TV camera in the direction of the voice is adopted. However, in the case of the fixed method, it is often difficult to bring the speaker's face, etc., into the field of view, and it is not possible to image materials, etc., which are not within the field of view. Also, in the case of the audio control method, the television camera may turn in the wrong direction in response to noise such as a note turning. In addition, both the preset method and the voice control method allow you to easily display a TV camera when you want to display materials that are not registered, such as on a desk. It is not possible to point in the direction, and it is necessary to move materials etc. into the field of view of the TV camera. Alternatively, it is necessary to manually turn the television camera in a desired direction using an operation means such as a joystick on the operation pad. However, in this case, there is a problem in that the speaker cannot concentrate on only the operation because of the operation, and the interest of the audience is distracted. Also, if the operation of a TV camera is left to others, it will be difficult to provide smooth materials in line with the progress of the topic.

On the other hand, in the above presentation device, the speaker simply moves the tip of the indicating member (8) to a position near the document and operates the indicating member (8), so that the television camera can be easily operated. (6) can be pointed in that direction. It can be displayed in lean (2). In addition, a position measuring device (1 2) is equipped with five transmitters (3) (5) placed on the screen (2) and in the space, and one transmitter attached to the pointing member (8). Since the position is measured using ultrasonic waves using the microphone (15), the transmitter (3) (5) and the microphone (15) must be placed on the screen (2) or in space. There is no need to provide any special equipment for position measurement-position measurement is relatively easy.

In the above embodiment, the indicating member U) is connected to the control unit (11) with the cable (20), and the signal transmission is performed by wire. However, the signal transmission may be performed wirelessly.

FIG. 18 shows an example of the configuration of a presentation device in a case where signal transmission is performed wirelessly.

In Fig. 18, the pointing member (8) is provided with two FM transmitters (64) (65), and the position measuring device (12) is provided with two FM receivers (66) (67). I have. Then, the received signal E from the microphone (15) is wirelessly transmitted from the transmitter (64) to the receiver (66), and further transmitted from the receiver (66) to the receiving device (24). Also, the switch signals from the buttons (16) to (18) and the switch (され) are wirelessly transmitted from the transmitter (65) to the receiver (66), and further transmitted to the receiver (66). ) Is transmitted to the mode switching device (22) and the arithmetic circuit (32). Others are the same as in the above embodiment, and the same parts are denoted by the same reference numerals.

If it is necessary to output the voice of the speaker through speed, a wired microphone device or a wireless microphone device provided separately from the above-mentioned presentation device can be used. In this case, the small microphone of the microphone device for voice can be attached to an appropriate place such as the clothes of the speaker. As shown in Fig. 18, the reception signal from the microphone (15) is transmitted wirelessly in the presentation device, and when a wireless microphone device for voice is used separately, the ultrasonic signal This means that two channels are used for voice and voice signals, and there is a possibility of crosstalk between the two channels within the usable bandwidth specified by the Radio Law. This problem can be solved by transmitting the ultrasonic signal and the audio signal in one channel.

FIG. 19 shows an example of a configuration in which the transmission of the ultrasonic signal and the audio signal is performed in one channel in the presentation device shown in FIG.

In FIG. 19, a microphone (receiver) (68) for voice is provided on the pointing member (8) side in addition to the microphone (15) for position measurement. Further, a mixer (69) as signal superimposing means is added to the indicating member (8). As the microphone for audio (68), a microphone whose reception sensitivity is limited to an audible band, such as a dynamic microphone, is used. The microphone for sound (68) may be attached to an appropriate place such as the base end portion of the indicating member (8), or may be provided separately from the indicating member (8) and provided on the clothes of the speaker. It may be attached. On the other hand, on the control unit (11) side, a low-frequency filter (61) for cutting off the ultrasonic frequency, an audio amplification circuit (62) and a speaker (63) are added. In this case, the received signal from the microphone (15) is mainly an ultrasonic signal received from the transmitter (3) (5), and the received signal from the microphone (68) is This is an audio signal in the audible band that receives the voice of the speaker. Then, the ultrasonic signal and the audio signal from the two microphones (15) and (68) are superimposed and output by the mixer (69), and this output is transmitted from the FM transmitter (64) to the FM receiver (66). ) Is transmitted wirelessly. Receiver The received signal E received at (66) is input to the low-pass filter (61) in addition to the receiving circuit (32). The reception signal E is obtained by superimposing the ultrasonic signal and the audio signal as described above. However, in the low-pass filter (61), the audio signal in the audible band is separated from the reception signal E and amplified. The signal is sent to the speaker (63) via the circuit (62), and the sound is played from the speaker (63). The audio signal output from the low-pass filter (61) is sent to the control device (13) and can be used for commanding and controlling by voice. In addition, by controlling the amplifier circuit (62) by the control device (13) in response to a command from the indicating member (8), it is possible to prevent sound from being output from the speaker (63) or from being output. it can. The other parts are the same as those in the embodiment of FIG. 18, and the same parts are denoted by the same reference numerals.

In the case of the embodiment shown in FIG. 19, only one occupied channel for transmitting the ultrasonic signal and the audio signal is required, and no crosstalk occurs. Also, since a separate wireless microphone device for voice is not required, cost can be reduced.

In the embodiment shown in FIG. 19, signal transmission between the mixer (69) and the receiving circuit (32) and the low-pass filter (61), and the buttons (16) to (18) And switch (19) and mode switching device

The transmission of signals between (22) and the arithmetic unit (35) can of course be performed by wire. Also in this case, an analog signal line for the acoustic signal of the ultrasonic signal and the audio signal is also provided.

You only need one.

In the embodiment of FIG. 19, a microphone (15) for position measurement and a microphone (68) for sound are provided separately, but as shown in FIG. 20, the microphone (15) is provided on the pointing member (8). One microphone (15) for position measurement It can also be used for audio.

The presentation device shown in FIG. 20 is obtained by removing the microphone (68) for sound and the mixer (69) from the embodiment of FIG. The microphone (15) is a receiver that receives the ultrasonic waves from the transmitters (3) and (5), a receiver for the voice that receives the voice of the speaker, etc., and superimposes the ultrasonic signal and the audio signal. Also serves as a signal superimposing means, and the reception signal E of the microphone (15) is a superposition of an ultrasonic signal and an audio signal. The received signal E from the microphone (15) is transmitted by radio from the FM transmitter (64) to the FM receiver (66), and is received from the receiver (66) to the receiving circuit (32) and the low-pass filter (66). 61). Other parts are the same as those in the embodiment of FIG. 19, and the same parts are denoted by the same reference numerals.

In the case of the embodiment shown in FIG. 20, only one microphone for the ultrasonic signal and one microphone for the audio signal is required, so that the cost can be further reduced.

In the above embodiment, the position measuring device (12) measures both the three-dimensional position in space and the two-dimensional position on the screen (2). In some cases, it is not necessary to measure the two-dimensional position.

FIG. 21 shows an example of the configuration of the presentation device in a case where the part relating to the two-dimensional position measurement is removed from the embodiment shown in FIG.

In FIG. 21, the mode selection button (16) has been removed from the indicating member (8). Also, the two-dimensional transmitter (3) and the mode switching device (22) are removed from the position measurement device (12), and each transmission circuit (26) is always connected to the corresponding three-dimensional transmitter (5). The other parts are the same as those in the embodiment of FIG. 19, and the same parts are denoted by the same reference numerals. In the case of the embodiment of FIG. 21, the image display device (10) may display an image on the screen (2) of the above embodiment. However, in this case, the screen (2) is used only for displaying the image. Further, the image display device (10) may display an image on a TV, a liquid crystal display panel, or the like. When the image display device (10) uses a TV, the presentation can be used for a video conference or the like. In such a case, the image signal and the audio signal are transmitted from the control unit (U) to the TV installed in another place via appropriate communication means. The image display device (10) may display a three-dimensional image on a stereoscopic TV. In this case, for example, two TV cameras separated by human eyes capture images for the right and left eyes. Using these images, a display screen with a lenticular lens or the like Display a 3D image on top.

In the embodiment shown in FIG. 21, the voice microphone (68) may be attached to the indicating member U). Further, one microphone (15) may be used for both ultrasonic and audio without providing a separate microphone (68) for audio. Especially in the latter case, when the singer sings with the pointing member (8) when the presentation is used in a karaoke studio or the like, the television camera (6) tracks this and the TV The singer's image is displayed on the display screen of the image display device (10), the singer's image is combined with the singer's image, or the singer is the pointing member. (8) You can adjust the volume by operating.

Further, in the embodiment shown in FIG. 21, the signal transmission between the pointing member (8) and the position measuring device (12) is performed by wire. Of course it is possible.

The presentation device may be permanently installed in a conference room or event hall, etc., and may be used exclusively. Alternatively, the entire presentation device may be portable and installed at a desired location. May be used.

As the indicating member U), the base end provided with the mode switching button (16), the upper button (Π) and the lower button (18), and the microphone (15) and the tip switch ( It is also possible to use one that can expand and contract with the tip provided with 19).

FIGS. 22 and 23 show an example of the extendable indicating member (77) as described above. In these drawings, the same reference numerals are given to portions corresponding to the indicating rod (8) in the above embodiment.

The indicating member (77) includes an operation unit (70), an expansion and contraction unit (71) having a base end fixed to the operation unit (70), and a detection unit (71) fixed to a distal end of the expansion and contraction unit (71). 72). The operation unit (7G) is designed so that the user can operate it by hand. The telescopic part (71) includes a plurality of nested cylinders (73a), (b) and (He). The rear end base body (73a) is fixed to the upper part of the operation section (71), and the detection section (72) is fixed to the front end of the front end cylinder (He). The detection section (72) is fixed to the tip cylinder (73c) and has a tapered tip at the end of the cylindrical case (74), and is attached to the tip of the case (74) so as to be movable back and forth. A pressing member (75) urged forward by a spring (not shown) is provided.

FIG. 22 shows a state in which the elastic part (71) is extended, and FIG. 23 shows a state in which the elastic part (71) is contracted. When the elastic part (71) is contracted, the rear part of the case (74) of the detecting part (72) is the upper front end of the operating part (70). They are going to enter the club. The operation section (70) is provided with a shortened state detection switch (7δ) for detecting that the extendable section (71) is in the shortened state by detecting the case (74). I have. A mode 'selection button (16), an upper button (Π), and a lower button (18) similar to the case of the indicator rod (8) of the above embodiment are provided on the operation unit (70). I have. A microphone (15) similar to the case of the indicator rod (8) of the above embodiment is provided in the front part of the pressing member (75) which always projects forward from the case (74) of the detection part (72). . A tip switch (19) similar to that of the indicator rod (8) in the above embodiment is provided in the case (74) of the detection section (72). The tip switch (19) detects that the pressing member (75) has moved to the rear side to detect that the pressing member (75) has been pressed against the screen (2) or the like. It is designed to detect.

Although not shown, an extendable spiral coil wire having a plurality of conductors is passed through the tubular body (73a) (731)) (73c) of the extendable portion (71). The power supply and signal transmission between the base end (70) and the detection unit (72) are performed by the wire conductor. The expansion / contraction part (Π) is composed of a plurality of sets of cylinders made of a conductor, and these cylinders are used to supply power and transmit signals between the base end (70) and the detection unit (72). It may be. Alternatively, a battery is provided in the detection section (72), and the light-emitting element and the light-receiving element are arranged so that the detection section (72) and the operation section (70) face each other through the cylinder (Ha) (Hb) (lU). May be provided to transmit a signal.

When this pointing member (77) is used in a presentation device as shown in FIG. 1, for example, the mode selection button (16) is switched to the two-dimensional mode side and the expansion and contraction section (71) is used. Is set to the handwriting mode only when Only while the member (75) is pressed against the screen (2), the position is measured and handwriting input is performed.

Other points are the same as those of the pointing member (8) of the above embodiment. Industrial applicability

The position measuring method and apparatus according to the present invention are suitable for use in two-dimensional or three-dimensional position measurement using ultrasonic waves.

Claims

Claims. A plurality of transmitters arranged at predetermined intervals intermittently transmit ultrasonic waves having different frequencies intermittently and almost simultaneously, and receive one ultrasonic wave attached to the object to be measured. The signal received by the receiver is passed through a plurality of band-pass filters having narrow-band characteristics having different center frequencies from each other, and the received signal for each transmitter for the ultrasonic wave from each transmitter is individually detected. The distance from each transmitter to the receiver is determined based on the elapsed time from the start time of transmission of ultrasonic waves by the transmitter to the detection time of the corresponding reception signal for each transmitter, and the measured object is determined based on these distances. A position measuring method characterized by obtaining a position of a position.

2. The position measuring method according to claim 1, wherein the position of the object to be measured is measured in a coordinate system based on a display screen of the image display device.

. Position measuring method according to claim 1, characterized in that to measure the three-dimensional position of the object to be measured in a predetermined space around the image pickup device capable of adjusting angle by the position information _(. Prescribed A plurality of transmitters arranged at intervals, one receiver attached to the object to be measured, a transmission device that transmits ultrasonic waves of different frequencies from each transmitter intermittently and almost simultaneously, Receiver that individually detects the received signal for each transmitter for the ultrasonic wave from each transmitter by passing the received signal of the transmitter through a plurality of band-pass filters having narrow band characteristics having different center frequencies, and each transmitter The distance from each transmitter to the receiver and the object to be measured are based on the elapsed time from the ultrasonic transmission start time by the transmitter to the detection time of the corresponding reception signal for each transmitter A position measuring device comprising a processing device for determining the position of the position.

5. The bandpass filter has two piezoelectric ultrasonic transducers of the same frequency as the corresponding ultrasonic wave, and the resonators of these ultrasonic transducers face each other at a distance of about one wavelength of the corresponding ultrasonic wave. Claim 4 characterized in that the input signal is applied to the electrode of one of the transducers and the output signal is extracted from the electrode of the other transducer. The position measuring device according to item 1.

6. An operation section provided with an operation switch means for operating the object to be measured by holding it with a hand, an expandable and contractible section having a base end fixed to the operation section, and an expandable and contractible section. 6. The position measuring device according to claim 5, further comprising: a detector fixed to a tip of the sensor, wherein a receiver is attached to the detector.