JP2003029917A - Coordinate input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a coordinate calculation accuracy by eliminating or mitigating the influence of the reflected waves of ultrasonic waves in an ultrasonic wave type coordinate input device. SOLUTION: A signal 13 corresponding to the envelope 121 is taken out from the detection signal 12 of a sensor detecting the ultrasonic wave from the input point of coordinates and the signal 16 for which it is 4th-order differentiated is generated. Further, a tg signal 17 indicating an ultrasonic wave detection timing by the envelope 121 is generated by the comparison of the signal 16 and a gate signal 132 to be valid only while the level of the signal 13 is equal to or higher than a reference level signal 131. A phase signal 19 indicating the phase 122 is generated from the detection signal 12 and a tp signal 20 indicating the ultrasonic wave detection timing by the phase 122 is generated by the comparison of it and the gate signal 171 for which the signal 17 is inverted. On the basis of the respective ultrasonic wave detection timings by the tg signal 17 and the tp signal 20, the coordinates of the input point are calculated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate input device for detecting coordinates of an arbitrarily designated coordinate input point, and more particularly to an ultrasonic coordinate input device for detecting coordinates using ultrasonic waves. It is a thing.

[0002]

2. Description of the Related Art At present, a display device for displaying various information output by a computer, and its display screen as a coordinate input surface, are arbitrarily designated by an input pen (pen-shaped coordinate input point designating means) on the display screen. There is an information input / output device including a coordinate input device that detects coordinates of a coordinate input point (hereinafter abbreviated as input point) and outputs coordinate data to a computer.

There are CRTs, LCDs, PDPs, projectors, etc. as the display devices that constitute this information input / output device.
In recent years, flat panels such as LCDs and PDPs have expanded their share in the display device market from the viewpoints of improved display performance and installation space.

On the other hand, the coordinate input device is called a touch panel or a tablet. When an input pen is used to point (touch) an arbitrary input point in the inputtable area of the coordinate input surface, the coordinate of the input point is detected, This is a device that outputs coordinate data to a connected computer so that the computer can display the input point on a display device.

As a method for detecting the coordinates of the input point, a resistance film method, an electromagnetic induction method, and an ultrasonic method are particularly known, and various methods have been diversified so that the user can select them according to the price and the use. . In particular, the ultrasonic method has characteristics that it is resistant to electromagnetic noise and is inexpensive, so that active development is underway.

The ultrasonic system includes a vibration transmission plate system and an aerial ultrasonic system. In the vibration transmission plate method, an ultrasonic wave that is input from an input point designated by an input pen equipped with a vibrator that generates ultrasonic waves and is transmitted as vibration is transmitted to the vibration transmission plate that constitutes the coordinate input surface. The detection is performed by a plurality of ultrasonic sensors (vibration sensors) provided in the peripheral portion, and the coordinates (two-dimensional coordinates) of the input point are calculated based on the detection timing.

In the aerial ultrasonic system, ultrasonic waves radiated in the air from an input pen indicating an input point on the coordinate input surface are detected by a plurality of ultrasonic sensors provided on the periphery of the coordinate input surface, The coordinates of the input point are calculated based on the detection timing. In this method, not only the input points on the coordinate input surface but also the input points in the space apart from the coordinate input surface
It is also possible to detect dimensional coordinates.

[0008]

In the above-mentioned aerial ultrasonic type coordinate input device, the ultrasonic waves radiated in the air are severely attenuated, and the attenuation is proportional to the square of the ultrasonic frequency. For this, ultrasonic waves in a somewhat low frequency band are used. However, the ultrasonic wave detection signal that the ultrasonic sensor detects and outputs ultrasonic waves is still weak and is not suitable for performing signal processing as it is. Therefore, amplification using a preamplifier is not recommended. It is common.

In this coordinate input device, there is a problem in that the level of the ultrasonic wave detection signal fluctuates significantly, and the accuracy of coordinate calculation deteriorates under the influence of the fluctuation. Factors that cause the level fluctuation of the detection signal include the ultrasonic wave transmission distance, the angle of the input pen, and the variation of each component. Normally, the threshold value for determining that the detection signal is valid is determined in consideration of the level fluctuation range due to the above factors, the level of the unnecessary reflected wave, the electromagnetic noise level, and the power supply voltage.

Regarding the unnecessary reflected wave, the reflected wave from the coordinate input surface of the coordinate input device as shown in FIG. 2 is the main one, but when inputting from a position distant from the coordinate input surface of the coordinate input device. , There are reflected waves from an unspecified number of objects, such as a desk, located very close to the input pen.

Such a reflected wave has a difference in distance between the direct wave and the reflected wave in the transmission path of the ultrasonic wave from the position of the input pen that emits the ultrasonic wave, that is, from the input point of the coordinates to the ultrasonic sensor. In the following, when the difference in transmission path) is large, it does not affect the processing after ultrasonic wave detection. For example, when the used frequency is 40 kHz, if the transmission path difference is several tens mm (several wavelengths), the reflected wave and the direct wave can be separated, and the above processing is not affected.

However, when a sufficient transmission path difference cannot be obtained, an ultrasonic wave in which a reflected wave and a direct wave are superposed is detected and the detection signal is processed, resulting in an erroneous detection, and the coordinate calculation accuracy is reduced. It will deteriorate.

On the other hand, if a transmission path difference of several tens of millimeters is secured, the degree of freedom in the design of the device will be lost in the position of the transducer of the input pen that generates the ultrasonic wave, the configuration of the ultrasonic sensor, and the like. There's a problem. The problem due to the influence of the reflected wave and the influence of the level fluctuation of the ultrasonic detection signal can be applied to the vibration transmission plate type device to some extent.

The present invention has been made in view of the above problems, and reduces or eliminates the influence of reflected waves and the influence of level fluctuation of ultrasonic detection signals in an ultrasonic coordinate input device. An object is to provide a configuration that can obtain stable coordinate calculation accuracy.

[0015]

In order to solve the above-mentioned problems, according to the present invention, the ultrasonic wave generation is performed when the coordinate input point is instructed by the coordinate input point instructing means having the ultrasonic wave generating means. In the coordinate input device, the ultrasonic wave emitted from the means is detected by a plurality of ultrasonic wave detecting means arranged at a plurality of different positions, and the coordinate of the input point is calculated based on the detection timing. Envelope detecting means for extracting an envelope signal corresponding to the envelope of the ultrasonic detection signal output by the
Differentiating means for differentiating the envelope signal by four levels or more and outputting a differential signal, and a first gate signal for generating a first gate signal which is valid only while the signal level of the envelope signal exceeds a predetermined threshold level. A first means for comparing the differential signal and the first gate signal with a generating means, and for generating a first detection timing signal indicating an ultrasonic wave detection timing detected from the envelope of the ultrasonic wave detection signal based on the comparison result. Detection timing signal generating means, second gate signal generating means for generating a second gate signal that is valid only while the first detection timing signal is valid, and the phase of the signal from the ultrasonic detection signal. Comparing the second gate signal and the phase signal with a phase signal generating means for generating a phase signal indicating A second detection timing signal generating means for generating a second detection timing signal indicating the ultrasonic detection timing detected from the phase, and based on each of the ultrasonic detection timings by the first and second detection timing signals. The configuration of calculating the coordinates of the input point is adopted.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Two embodiments will be described here.

[First Embodiment] As a first embodiment of the present invention, a two-dimensional coordinate (x, y) of an input point designated on a coordinate input surface is calculated by an aerial ultrasonic coordinate input device. An embodiment of the calculating device will be described with reference to FIGS.

<Description of Overall Configuration (FIG. 1)> First, the overall configuration of the apparatus of this embodiment will be described with reference to FIG.

In FIG. 1, 1 is an arithmetic control circuit,
While controlling the entire coordinate input device, the coordinate of the input point designated on the coordinate input surface is calculated and output to the host device 4 such as a computer through a serial cable or the like.

Reference numeral 2 denotes an optical transmission / reception circuit, which detects an optical signal emitted from an input pen 21 described later and transmits an input pen control signal as an optical signal for controlling the operation of the input pen 21. .

Reference numeral 3 is a signal processing circuit, which is an optical transmission / reception circuit 2.
The optical signal detected in step S1 is processed and its data is output to the arithmetic control circuit 1, or the input pen control signal output from the arithmetic control circuit 1 is converted into a pulse train and output to the optical transceiver circuit 2.

An image projection device 5 such as a projector projects an image based on various image information output from the host device 4 onto a screen 8 made of acrylic, vinyl chloride or the like. The surface of the screen 8 is the display surface and the coordinate input surface of the coordinate input device.

Reference numeral 21 is an input pen as a pen-type coordinate input point designating means for the user of the apparatus to designate a desired input point on the coordinate input surface to input coordinates. The coordinate input by the input pen 21 is performed by pointing (touching) a desired input point within the effective area indicated by reference numeral 7 on the surface of the screen 8 as the coordinate input surface with the pen tip of the input pen 21.

The effective area 7 on the surface of the screen 8
Ultrasonic sensors 6a to 6d each including a piezoelectric element that converts mechanical vibrations due to ultrasonic waves into electric signals and detects ultrasonic waves are fixed to the four corners of the outer peripheral portion.

Reference numeral 9 denotes a sensor signal processing circuit, which processes an ultrasonic wave detection signal output from each ultrasonic wave sensor 6a to 6d and outputs the ultrasonic wave, and detects the ultrasonic wave detection timing of each sensor 6a to 6d ( Ultrasonic arrival timing to each sensor)
To generate a detection timing signal, and output each to the arithmetic control circuit 1.

The arithmetic control circuit 1 uses the input pen 21 based on the detection timing of the ultrasonic wave of each sensor based on the signal.
The two-dimensional coordinates (x, y) of the input point on the coordinate input surface designated by are calculated as described below and output to the host device 4.

The host device 4 outputs the input coordinate information as image information to the image projecting device 5, whereby the image projecting device 5 projects an image on the screen 8, and a dot or the like is formed at the position of the input point of the screen 8. Is displayed.

<Input pen 21 and ultrasonic sensors 6a to 6d
(FIG. 2)> Next, the input pen 21 and the ultrasonic sensors 6a to 6d will be described with reference to FIG.

In FIG. 2, a vibrator 25 as an ultrasonic wave generating means built in the input pen 21 is a vibrator driving circuit 2
Driven by 4. An electric drive signal from the circuit 24 is converted into mechanical ultrasonic vibration by a vibrator 25, and the ultrasonic wave is reflected by a conical reflecting material 27 made of a metal such as aluminum and passes through the ultrasonic wave. It is radiated into the air through the window 28.

The vibrator 25 is a piezoelectric vibrator that vibrates in the thickness direction and has an acoustic matching layer 26 provided on the front surface thereof. The acoustic matching layer 26 is made of a thin layer of silicon rubber or the like to match the acoustic impedance with the air, to obtain a broadband characteristic with high sensitivity, and to transmit an ultrasonic signal with good pulse response. I am trying.

The ultrasonic waves radiated into the air from the ultrasonic wave passage window 28 are conical reflectors 21 made of metal provided on the ultrasonic sensors 6a to 6d (only 6a is shown in FIG. 2).
It is reflected by 1 and detected by the ultrasonic sensors 6a to 6d, and the coordinates of the input point are calculated as described later based on the ultrasonic detection timing (ultrasonic arrival timing).

The vibrator drive circuit 24 pulse-drives the vibrator 25 at a predetermined number of its resonance frequency, and at the same time modulates the light emitting element 22 such as an infrared LED provided on the input pen 21 at a predetermined frequency. The light emission timing signal is transmitted.

The vibrator drive circuit 24 operates using the battery 23 as a power source. The battery 23 is an alkaline dry battery or the like.
A secondary battery or a secondary battery such as a nickel hydride battery,
It is exchangeable. The oscillator drive circuit 24 is the battery 2
The output voltage of 3 is used as the power supply voltage, and the pulse drive voltage of the vibrator 25 is also driven with the same voltage value as the power supply voltage.
If it is desired to raise the output level, it is possible to drive the vibrator 25 at a voltage higher than the power supply voltage via a step-up transformer or the like. However, it consumes a large current, which is disadvantageous from the viewpoint of battery life.

<Description of Overall Operation> Next, the overall operation of the coordinate input device will be described. As described above, the input pen 2
The vibrator driving circuit 24 in 1 outputs the light emission timing signal modulated to a predetermined frequency to the light emitting element 22 at the same time as driving the vibrator 25, and causes the optical signal corresponding thereto to emit light. The optical signal is detected by the optical transmission / reception circuit 2 and demodulated by the signal processing circuit 3, and then the arithmetic control circuit 1
It is input as a start timing signal for starting the timing of the transmission time of the ultrasonic waves transmitted to the ultrasonic sensors 6a to 6d.

The arithmetic control circuit 1 causes the internal timer (consisting of a counter) to start measuring the vibration transmission time in response to the start timing signal from the signal processing circuit 3. The ultrasonic wave generated from the transducer 25 of the input pen 21 is transmitted from the input point (strictly speaking, the position of the transducer 25) designated by the input pen 21 on the coordinate input surface to the ultrasonic sensors 6a to 6d. After reaching the ultrasonic sensors with a delay of a transmission time corresponding to the distance, the ultrasonic sensors detect the signals, and the detection signals are input to the sensor signal processing circuit 9 from the ultrasonic sensors.

The sensor signal processing circuit 9 is provided for each ultrasonic sensor 6
The signal processing described below is performed on the detection signals from a to 6d to generate an ultrasonic detection timing signal indicating the ultrasonic detection timing of each ultrasonic sensor (the timing of arrival of ultrasonic waves at each ultrasonic sensor). Input to the arithmetic control circuit 1.

The arithmetic control circuit 1 sets the time measured by the internal timer at the time of inputting each of the signals as the ultrasonic wave transmission time to the ultrasonic sensors 6a to 6d, and based on the data, the input pen The coordinates of the input point designated by 21 are calculated. Then, the arithmetic control circuit 1 inputs the calculated coordinate information of the input point to the host device 4, and the host device 4 controls the display of the image by the image projection device 5 based on the input coordinate information.

<Explanation of arithmetic control circuit 1 (FIG. 3)> Next,
The configuration and operation of the arithmetic control circuit 1 will be described with reference to the block diagram of FIG. In the figure, reference numeral 31 is a microcomputer for controlling the arithmetic control circuit 1 and the entire coordinate input device, including a CPU 311, which is the main body for performing control processing, a ROM 312 storing a control program thereof, a RAM 313 used as a working area for calculation, and the like. It is configured by a non-volatile memory or the like (not shown) that stores constants and the like.

Reference numerals 32a to 32d are counters constituting a timer for counting time by counting a reference clock (not shown), which correspond to the ultrasonic sensors 6a to 6d and measure the time of transmission of ultrasonic waves to each of them. To do. In the counters 32 a to 32 d, the optical transmitter / receiver circuit 2 detects an optical signal emitted from the light emitting element 22 at the same time when the driving of the vibrator 25 in the input pen 21 is started, and the start timing signal is sent to the arithmetic control circuit 1 via the signal processing circuit 3. When input, it is activated and starts counting time. This synchronizes the start of timing with the generation of ultrasonic waves from the transducer 25, and the ultrasonic wave transmission time from the input point until the ultrasonic waves are detected by the ultrasonic sensors 6a to 6d can be measured. Become.

When the ultrasonic sensors 6a to 6d detect ultrasonic waves, the detection signals are input to the sensor signal processing circuit 9, ultrasonic detection timing signals of the ultrasonic sensors 6a to 6d are generated, and the detection timing signal is input. It is input to the counters 32a to 32d via the circuit 34. Then, in the counters 32a to 32d, the data of the count value of the time when the ultrasonic detection timing signal is input is latched by the latch circuit (not shown) as the data of the ultrasonic wave transmission time to the ultrasonic sensors 6a to 6d. .

When the decision circuit 33 decides that all the ultrasonic wave detection timing signals of the ultrasonic wave sensors 6a to 6d have been received, it outputs a signal to that effect to the microcomputer 31. In response to the signal, the microcomputer 31 reads the timing data of the transmission time from the latch circuits of the counters 32a to 32d to the ultrasonic sensors 6a to 6d. Then, the coordinates of the input point by the input pen 21 on the screen 8 are calculated by performing the later-described calculation based on this time measurement data.

The ultrasonic detection timing signal is actually generated by the processing of the envelope of the detection signals of the ultrasonic sensors 6a to 6d and the processing of the phase as described later. There is a timing signal, and each of them measures two types of transmission times, and the coordinates of the input point are calculated based on each of them.

The microcomputer 31 outputs the coordinate information thus calculated to the host device 4 via the I / O port 35. The host device 4 can output image information to the image projection device 5 according to the input coordinate information, and can display a dot or the like at the position of the input point on the screen 8 by the input pen 21. Or I / O port 35
The coordinate information can be output to another external device via the interface circuit for the other external device.

<Description of Sensor Signal Processing Circuit 9 and Signal Processing (FIGS. 4 and 5)> Next, the configuration of the sensor signal processing circuit 9 will be described.
The signal processing and each ultrasonic sensor 6a based on it
Detection of the ultrasonic wave transmission time up to 6d will be described with reference to the block diagram of FIG. 4 and the timing chart of FIG. Note that the configuration and signal processing of the sensor signal processing circuit 9 for the ultrasonic sensor 6a will be described below, but the other ultrasonic sensors 6b to 6d are also provided with the same configurations as in FIG. Of course, similar signal processing is performed.

As described above, when the ultrasonic wave transmission time from the input point by the input pen 21 to the ultrasonic sensor 6a is measured, the counter 32a outputs the start timing signal from the signal processing circuit 3 to the arithmetic control circuit 1. Be started. At this time, the drive signal 11 is applied from the vibrator drive circuit 24 in the input pen 21 to the vibrator 25. As shown in FIG. 5, the drive signal 11 is a short rectangular pulse (for example, one shot). The reason why the drive signal 11 is a short pulse is to prevent erroneous detection due to interference (superposition) between the ultrasonic wave (direct wave) to be detected and the unnecessary reflection component, and to reduce the size of the entire apparatus.

By this drive signal 11, the input pen 21
The oscillator 25 is driven, and ultrasonic waves are radiated into the air.
The ultrasonic wave travels through the air for a transmission time corresponding to the distance from the input point of the input pen 21 (strictly speaking, the position of the transducer 25) to the ultrasonic sensor 6a, and then the ultrasonic sensor 6a.
detected in a.

The detection signal of the ultrasonic sensor 6a which has detected the ultrasonic wave at this time is shown by reference numeral 12 in FIG. This detection signal 12 is input to the configuration for the ultrasonic sensor 6a of the sensor signal processing circuit 9 shown in FIG.
After being amplified by 01, each of the envelope (envelope) 121 and the phase 122 of the waveform of the detection signal 12 shown in FIG. 5 is separated by the signal processing system below the envelope detection circuit 402 and the signal processing system below the band pass filter 408. Is processed.

First, regarding the envelope 121, the detection signal 12 is detected by the envelope detection (detection) circuit 402.
, The envelope signal 13 corresponding to the envelope 121 of the waveform is extracted by detection. The envelope signal 13 is input to the gate signal generation circuit 406. The gate signal generation circuit 406 uses the envelope signal 1
3 is compared with the reference level signal 131, and the gate signal 132 that is valid (low level) is output only while the signal level of the envelope signal 13 exceeds a predetermined reference level (threshold level) of the reference level signal 131.

Further, the envelope signal 13 is inputted to the envelope fourth-order differentiating circuit 404 and is fourth-order differentiated to generate the fourth-order differential signal 16. The fourth-order differential signal 16 and the gate signal 132 together with the differential signal comparator 405
Entered in.

The comparator 405 compares the fourth-order differential signal 16 and the gate signal 132, and while the gate signal 132 is open, that is, when the signal level of the envelope signal 13 is between the reference level signal 131 and above. While the gate signal 132 is at the low level, the fourth-order differential signal 16
The tg signal 17 that is valid (high level) is generated only while the waveform of is below the zero level shown by the broken line. This t
The first rising time at which the g signal 17 becomes valid first is the fourth derivative signal 16 while the gate signal 132 is valid.
The waveform of corresponds to the zero-cross point where the positive level first crosses the negative level to the zero level. That is, the tg signal 17
Detects the first zero-cross point of the waveform of the fourth-order differential signal 16 while the gate signal 132 is valid as the ultrasonic wave detection point by the envelope 121 of the detection signal 12,
The signal becomes valid at the time of the detection, and this signal is input to the arithmetic and control circuit 1 as an ultrasonic wave detection timing signal indicating the detection timing of the ultrasonic wave detected from the envelope 121.

In the arithmetic control circuit 1, the data of the count value of the counter 32a is latched when the tg signal 17 is input, and the time corresponding to the count value, that is, the input pen 21 is input.
From the rise of the drive signal 11 of the oscillator 25 of
The time tg until the first rising point of the signal 17 is the transmission time of the ultrasonic wave from the envelope 121 of the detection signal 12 to the ultrasonic sensor 6a detected.

On the other hand, in the processing for the phase 122 of the detection signal 12 of the ultrasonic sensor 6a, first, the detection signal 12 is converted into the signal 18 of the frequency component of the predetermined width by the narrow band pass filter 408, and further by the slice circuit 409. , The waveform is sliced below a predetermined amplitude level (waveform level compression). Then, the output signal of the slice circuit 409 is input to the phase signal comparator 410 as the phase signal 19 indicating the phase of the detection signal 12.

Further, the tg signal 17 output from the differential signal comparator 405 is input to the gate signal generating circuit 407 and inverted to generate the gate signal 171. The gate signal 171 corresponds to the tg signal 17, and is a signal that is opened (becomes an effective low level) only while the tg signal 17 is effective (high level). This gate signal 171 is also input to the phase signal comparator 410.

The comparator 410 compares the phase signal 19 with the gate signal 171, and during the effective low level when the gate signal 171 is open (while the tg signal 17 is effective).
Of the phase signal 19 is extracted and output as a tp signal 20 which is an ultrasonic detection timing signal indicating the ultrasonic detection timing detected from the phase 122.

This tp signal 20 is input to the arithmetic control circuit 1. The rising time of the first pulse of the pulses of the tp signal 20, that is, the time when the tp signal 20 first becomes valid is the ultrasonic detection time detected from the phase 122, and at this time, the count value of the counter 32a is changed. The ultrasonic sensor in which the data is latched, and the time according to the count value, that is, the time tp from the rise time of the drive signal 11 of the vibrator 25 of the input pen 21 to the rise time of the first pulse of the tp signal 20 is detected from the phase 122 The transmission time of ultrasonic waves up to 6a is set.

<Explanation of Calculation of Distance between Input Point and Ultrasonic Sensor> Next, the operation of the input pen 21 performed by the arithmetic control circuit 1 based on the ultrasonic wave transmission times tg and tp measured as described above. Calculation of the distance between the input point and the ultrasonic sensors 6a to 6d will be described. In the following description, the position of the input point designated by the pen tip of the input pen 21 on the coordinate input surface and the position of the transducer 25 are considered to be substantially the same.

Since the ultrasonic waves used in the apparatus of this embodiment are transmitted through the air, the relationship between the envelope 121 and the phase 122 of the waveform of the detection signal 12 of the ultrasonic sensors 6a to 6d depends on the transmission distance of ultrasonic waves. It is constant regardless of. Here, the traveling speed of the envelope 121, that is, the group velocity is Vg, and the traveling speed of the phase 122, that is, the phase velocity is Vp. From the group velocity Vg and the phase velocity Vp, the input pen 21
The distance between the input point and the ultrasonic sensor 6a can be detected.

First, focusing only on the envelope 121, its speed is Vg, and at a specific point on the waveform of the envelope 121 (in this embodiment, the first zero-cross of the fourth derivative signal 16 while the gate signal 132 is open). The ultrasonic wave transmission time up to the point of detection of
The distance d between the input point of the input pen 21 and the ultrasonic sensor 6a is given by d = Vg · tg (1). This equation relates only to the ultrasonic sensor 6a, but the same equation applies to the other three ultrasonic sensors 6a.
The distances between b to 6d and the input point can be similarly expressed.

However, since the linearity of the time tg with respect to the distance d is not good, in order to determine the coordinates with higher accuracy, the ultrasonic wave detection timing detected from the phase 122 of the detection signal 12 is used as described above. Ultrasonic wave transmission time tp
Perform processing based on. This transmission time tp and the phase velocity V
From p, the distance d between the ultrasonic sensor 6a and the input point is d = n · λp + Vp · tp (2). Here, λp is the wavelength of ultrasonic waves and n is an integer.
From the expressions (1) and (2), the integer n is the following (3),
It can be calculated by equation (3) '.

N = int [(Vg · tg-Vp · tp) / λp + 1/2] (3) From V = Vg = Vp n = int [V · (tg-tp) / λp + 1/2] (3) ′ Here, it cannot be said that the linearity of the transmission time tg due to the envelope with respect to the distance d is good, and this is the reason why the expression (3) 'is converted into an integer. The necessary and sufficient condition for obtaining the exact integer n is the formula derived from the following formula (4).
As shown in (5), n * = V · (tg-tp) / λp (4) ΔN = n * -n ≦ 0.5 (5) That is, if the generated error amount is within ± 1/2 wavelength If
This shows that the integer n can be accurately determined even if the linearity of the transmission time tg by the envelope is not good. By substituting n obtained as described above into the equation (2), the distance d between the input point of the input pen 21 and the ultrasonic sensor 6a can be calculated accurately. The distance between each of the other ultrasonic sensors 6b to 6d and the input point can be calculated in exactly the same manner with high accuracy.

<Description of Coordinate Calculation (FIG. 6)> Next, calculation of the coordinates of the input point based on the distance between the input point calculated as described above and the ultrasonic sensors 6a to 6d will be described with reference to FIG.

If the four ultrasonic sensors 6a to 6d are provided at the four corners Sa to Sd on the surface of the screen 8 shown in FIG. 6, that is, on the coordinate input surface, the transmission time at the ultrasonic detection timing described above is reduced. Based on this, in the arithmetic control circuit 1, the straight line distance da from the input point P of the input pen 21 to the positions Sa to Sd of the ultrasonic sensors 6a to 6d is
dd can be calculated.

Further, in the arithmetic control circuit 1, the linear distance d
Based on a to dd, the coordinates (x, y) of the input point P can be obtained from the following equations (6) and (7) from the Pythagorean theorem.

X = (da + dd) · (da−dd) / 2X (6) y = (da + db) · (da−db) / 2Y (7) where X and Y are between the ultrasonic sensors 6a and 6d, respectively. The distance and the distance between the ultrasonic sensors 6a and 6b. As described above, the coordinates of the input point of the input pen 21 can be calculated in real time.

The above calculation can be performed by using the distance information between the input point P and the three ultrasonic sensors. However, in this embodiment, four ultrasonic sensors are installed, and the remaining 1 The distance information between each ultrasonic sensor and the input point P may be used to verify the accuracy of the coordinates calculated by the above calculation.

Further, for example, the distance information of the ultrasonic sensor whose distance L from the input point P is the largest (the distance L becomes large, the ultrasonic detection signal level decreases and the influence of noise increases). Instead of using it, the coordinates may be calculated using the distance information of the remaining three ultrasonic sensors.

For the reason described later, the coordinate information of the input point in the vicinity of a certain ultrasonic sensor may be calculated by using the distance information of the other ultrasonic sensor instead of using the distance information of the ultrasonic sensor. Good.

Further, although four ultrasonic sensors are arranged in this embodiment, it goes without saying that the number of sensors is set according to the product specifications.

According to the present embodiment as described above, as shown in FIG. 5, the tg signal 1 which is the time point of ultrasonic wave detection by the envelope 121 of the ultrasonic wave detection signal 12 of the ultrasonic sensor.
The first rising point of 7 and the rising point of the first pulse of the tp signal 20, which is the ultrasonic wave detection time by the phase 122, are before the peak of the envelope signal 13. That is, in the part of the detection signal 12 before the peak of the envelope 121, the reflected wave component of the ultrasonic wave is not superposed, or even if the superposed wave component is small, the ultrasonic wave is detected by the process of the part before the peak. Because you get the timing,
Ultrasonic detection can be performed with high accuracy by eliminating or reducing the influence of reflected waves. Therefore, the transmission times tg and tp can be measured with high accuracy, and the distance between the input point and the ultrasonic sensor and the coordinates can be calculated with high accuracy.

The results obtained by confirming the performance of the apparatus of this embodiment by experiments will be described with reference to FIG. FIG. 7 shows the measurement of the distance L between the input point of the input pen and the ultrasonic sensor based on the detection of the ultrasonic wave by the envelope and the timing of the transmission time tg described in the configurations of the respective devices of this embodiment and the conventional example. The relationship between the distance L as a result of (calculation) and the measurement error ΔL is shown.

In the conventional example, an inflection point detection circuit (second order differentiation circuit) for detecting an inflection point of the envelope 121 is used in place of the envelope fourth order differentiation circuit 404 in the configuration of the sensor signal processing circuit of FIG. The gate signal 13 in its output signal (denoted by reference numeral 15 in FIG. 5).
The time point of the first zero-cross point while 2 is opened is the ultrasonic wave detection time point.

As can be seen from FIG. 7, in the present embodiment,
Compared to the conventional example, the measurement error Δ over the entire distance L
L is extremely small and good linearity is obtained. This good linearity shows that the margin of ΔN in the above equation (5) becomes large. Therefore, according to this embodiment, the coordinates of the input point can be calculated with high accuracy.

In the measurement result of the present embodiment shown in FIG. 7, a part where the distance L is smaller than 100 mm, that is, a non-linear part is recognized when the input point is close to the ultrasonic sensor. Occurs when the waveform of the ultrasonic wave detection signal of the ultrasonic wave sensor is deformed when is close to the ultrasonic wave sensor. For this phenomenon, when the input point is close to one of the four ultrasonic sensors 6a to 6d, that sensor is not used and is based on the ultrasonic detection signals of other sensors. It can be dealt with by calculating coordinates.

Further, in this embodiment, in order to detect the transmission time tp by the phase of the ultrasonic wave, the phase signal 19 is not used as it is, but the tp signal corresponding to the portion of the phase signal 19 during which the gate signal 171 is effective. Since the transmission time tp is detected by using 20, the detection signal 1 of the ultrasonic sensor 1
It is possible to reduce or eliminate the influence of the level fluctuation of 2. For example, assuming that the rising time of the first pulse of the phase signal 19 is the detection time of the ultrasonic wave, the generation time of the first pulse of the phase signal 19 shifts back and forth due to the fluctuation of the signal level of the detection signal 12, so that The sound wave detection time is also shifted back and forth, but this is not the case with the tp signal 20.

In the above-described embodiment, the rising time of the first pulse in the tp signal 20 as a part of the phase signal 19 while the gate signal 171 of FIG. However, the time point of falling of the same pulse, or the time point of rising or falling of another pulse such as the second pulse may be used as the ultrasonic wave detecting time. Which time point should be the ultrasonic wave detection time is determined according to the specifications of the apparatus such as the sampling rate for coordinate detection.

Also, the envelope signal 13 is fourth-order differentiated by the envelope fourth-order differentiating circuit 404 to obtain the envelope 4
Although the differential signal 16 is generated, it may be generated by differentiating the fifth order or higher to generate the differential signal of the fifth order or higher of the envelope. However, when the number of floors is increased, the noise margin of the circuit is reduced, and at the same time, signal delay in the circuit becomes a problem. Therefore, it is appropriately determined in consideration of the influence of the reflected wave.

Although the embodiment of the airborne ultrasonic coordinate input device has been described above, it is needless to say that the configuration according to the present invention can be applied to a vibration transmitting plate system device which is another ultrasonic system.

[Second Embodiment] Next, as a second embodiment of the present invention, an aerial ultrasonic type coordinate input device is used to input an input on a coordinate input surface or in a space away from the coordinate input surface. An embodiment of an apparatus for calculating the three-dimensional coordinates (x, y, z) of a point will be described with reference to FIGS.

The hardware configuration of the device of this embodiment is the same as that of the first embodiment described above except that the configuration of the input pen 21 is slightly different as will be described later.
The description of the other configurations is omitted. Further, in the coordinate input operation of the apparatus of the present embodiment, from driving the transducer 26 of the input pen 21 to calculating the distance between the input point (position of the transducer 25 of the input pen 21) and the ultrasonic sensors 6a to 6d, In common with the first embodiment, description thereof will be omitted, and description will be made from the calculation of the three-dimensional coordinates of the input point based on the distance.

<Description of Calculation of Three-Dimensional Coordinates (FIG. 8)> FIG.
As shown in FIG. 5, the surface of the screen 8 on which the ultrasonic sensors 6a to 6d are arranged on four sides, that is, the display surface and the coordinate input surface is an XY plane passing through the X axis and the Y axis at right angles, and Z is the axis perpendicular to the surface and orthogonal to the X and Y axes.
The axis.

In this three-dimensional coordinate system, the input point of the input pen 4 (position of the transducer 25 of the input pen 21) and the ultrasonic sensors 6a, 6b, 6 obtained by the above-mentioned method.
Let c, 6d be La, Lb, Lc, Ld, Xs-s the distance between X-axis ultrasonic sensors, and Ys-s the Y-axis distance between ultrasonic sensors.

[0082]

[Equation 1] Is. Similarly,

[0083]

[Equation 2] Is. Therefore, the above equations (9), (10), (1
The microcomputer 3 of the operation control circuit 1 performs the operation 1).
By performing the step 1, the three-dimensional coordinates (x, y, z) of the input point of the input pen 4 can be calculated.

By the way, the above equations (9), (10),
As can be seen from (11), the input point of the input pen 21 and the 3
Distance from each ultrasonic sensor (here, La, Lb, L
If c) can be measured, it becomes possible to obtain the three-dimensional coordinates of the input point.

On the other hand, in this embodiment, since four ultrasonic sensors are used, for example, the distance information of the ultrasonic sensor having the longest distance from the input point is not used (in this case, The ultrasonic detection signal has the lowest signal level because the distance is long.) By calculating the coordinates using only the remaining three pieces of distance information, it is possible to calculate the coordinates with high reliability.

Further, it is possible to determine whether or not the reliability of the output coordinate value is high by utilizing the information of the sensor whose distance is long. As a concrete method, when the combination of three pieces of distance information is changed and calculation is performed, for example,
The coordinate value calculated by the distance information La, Lb, Lc and the coordinate value calculated by the distance information Lb, Lc, Ld should be the same. If the two do not match, one of the distance information is incorrect. That is, since it is erroneously detected, in that case, a configuration of improving reliability by a method of not outputting the coordinate value can be implemented.

<Description of Configuration of Input Pen (FIG. 9)> Next, the configuration of the input pen 21 of the present embodiment will be described with reference to FIG.
The internal configuration of the input pen 21 of the present embodiment shown in FIG. 9 is the same as the configuration described above with reference to FIG. 2 of the first embodiment, and the light emitting element 22, the battery 23, the oscillator drive circuit 24, the oscillator 25, etc. It is provided and these operations are also common.

In addition to this internal structure, in the input pen 21 of this embodiment, as shown in FIG. 9, a pen tip switch 41 is provided at the tip and two pen side switches 42a and 42b are provided at the side surfaces. ing. The operation mode of the input pen is switched as described below according to the on / off state of these switches.

<Description of Operation Mode (FIGS. 10 to 13)>
Next, the operation mode of the coordinate input device according to the present embodiment will be described with reference to FIGS. In the present embodiment, FIG.
As shown in the table of No. 0, the pen tip switch 4 of the input pen 21
In accordance with ON and OFF of 1 and the pen side switches 42a and 42b, the drive mode of the vibrator 25, which is an ultrasonic wave generation source, is switched to a first or second drive mode described later,
As a result, the pen-down state in which writing input is performed with the input pen 21 and the pen-up state in which the cursor is moved are switched.

Further, as a mode of input operation by the input pen 21, a direct input mode in which the input pen 21 is brought into direct contact with the surface of the screen 8 as a coordinate input surface to perform writing input, and a mode in which the input pen 21 is in the screen 8 are used. The first predetermined distance in the Z-axis direction from the screen 8 without touching
For example, a proximity input mode in which coordinates are input within a space of 300 mm or less, and a second predetermined distance larger than the first predetermined distance in the Z-axis direction from the screen 8, for example, 10
It can be divided into a remote input mode in which coordinates are input in a space separated by 00 mm or more.

Then, the output coordinate mode for outputting the data of the calculated coordinate value is switched to the absolute coordinate mode in the direct input mode and the proximity input mode, and to the relative coordinate mode in the remote input mode. In the absolute coordinate mode, the data of the values of the x coordinate and the y coordinate of the three-dimensional coordinates (x, y, z) calculated for each sampling is output as it is as the absolute coordinate data. In the relative coordinate mode, for each sampling, the difference values Δx and Δy between the calculated values of the x and y coordinates calculated in the sampling and the calculated values of the x and y coordinates calculated in the previous sampling are obtained. The data is output as relative coordinate data.

First, the details of the operation modes switched by the switches 41, 42a, 42b will be described.

As shown in the table of FIG. 10, the vibrator 25 is driven in the first drive mode or the second drive mode depending on whether the pen tip switch 41 and the pen side switches 42a and 42b are turned on or off. . In the first drive mode, FIG.
Drive signal 9 for the oscillator 25 shown in the timing chart of FIG.
02, that is, the cycle of the drive timing signal 901 for generating this signal, and the sampling cycle of the coordinate input is, for example, 50 times / second, and in the second drive mode, a different cycle, for example, 40 times / second. Seconds.

On the main body side of the coordinate input device, the microcomputer 31 drives the oscillator 25 due to the difference in the period of the sound waves detected by the ultrasonic sensors 6a to 6d, that is, the sampling period which is the drive period of the oscillator 25. The mode is discriminated, and in the first drive mode, the operation mode of the input pen 21 is recognized as a pen-down state in which a character or the like can be input for writing by the coordinate input operation, and the coordinate input process for that is performed. In the second drive mode, the coordinate input operation by the input pen 21 is recognized as a pen-up state in which the cursor can be moved on the display screen of the display 6, and the coordinate input process for that is performed.

In the pen-down state where the handwriting input is performed, it is preferable to input more detailed coordinate data than in the pen-up state where the cursor movement or the like is performed (to reproduce the handwriting more faithfully). The sampling cycle of (first drive mode) is set shorter than that of the pen-up state (second drive mode).

The control of switching the drive mode of the vibrator 25 is performed by the control circuit constituting the vibrator drive circuit 24 of the input pen 21 in the procedure shown in the flowchart of FIG. That is, after starting the control process in step S201, steps S202, S203,
In S204 and S205, it is sequentially determined whether or not the pen tip switch 41 and the pen side switches 42a and 42b are turned on, and when the pen tip switch 41 is turned on and when both the pen side switches 42a and 42b are turned on. In step S207, the vibrator 25 is driven in the first drive mode to bring it into the pen-down state. If only one of the pen side switches 42a and 42b is turned on, the vibrator 25 is driven in the second drive mode in the step S206, and the pen-up state is set. And step S2
The processing ends at 08. In addition, each switch 41, 42
If neither a nor 42b is turned on, the process is terminated.

With such control, the actual input pen 2
The operation corresponding to the operation 1 is as follows.

That is, first, the operator holds the input pen 21 and inputs desired coordinates on the coordinate input surface (in this case, the surface of the screen 8 on which the XY plane (z = 0) is set as shown in FIG. 9). When the point is pressed, the pen tip switch 41 turns on. In this case, the oscillator drive circuit 24 drives the oscillator 25 in the first drive mode at a cycle of, for example, 50 times / second, and a sound wave is radiated into the air at that cycle.

Then, enter the input pen 2 on the main body of the coordinate input device.
The operation mode No. 1 is recognized as a pen-down state, and the operator can perform writing input such as characters by tracing the coordinate input surface with the input pen 21. The output coordinate mode is the absolute coordinate mode, and the three-dimensional coordinates x, y, z (z = z) of the calculated coordinate input point (position of the transducer 25) are set.
The data of the x-coordinate value and the y-coordinate value of 0) is output as it is, and the writing input is performed.

On the other hand, when the pen tip switch 41 is in the off state, it means that the input pen 21 is away from the screen 8 and at least the coordinates are not input by the operator within the XY plane (z = 0). means. Even in that case, it is preferable that an operation such as moving the cursor displayed on the screen 8 can be performed by operating the input pen 21. Therefore, the pen side switches 42a, 42a
By pressing only one of b to turn it on, the vibrator 25 is driven in the second drive mode at a cycle of, for example, 40 times / second, and sound waves are radiated into the air at that cycle, so that the device main body side It is recognized as a pen-up state. Then, in the pen-up state, an operation such as moving the cursor can be performed by coordinate input accompanying the movement of the input pen 21.

If the user wants to perform writing input even when the input pen 21 is far from the coordinate input surface (z> 0),
By pressing both the pen side switches 42a and 42b to turn them on, the vibrator 25 is driven in the first drive mode to be in the pen-down state, and writing can be input.

As shown in FIG. 9, the pen side switches 42a and 42b are arranged adjacent to each other on the side surface of the input pen 21 so as to form an angle of about 90 degrees in the circumferential direction. As a result, when the operator grips the input pen 21, regardless of the operator's right-handedness or left-handedness, one of the pen side switches 42a and 42b can naturally touch the thumb and the other with the forefinger. There is. Since the same operation mode (second drive mode, pen-up state) can be switched even if only one of the pen side switches 42a and 42b is turned on, the operation mode switching operation is performed regardless of the dominant hand of the operator. Is easy to use and easy to use.

Also, one pen side switch is used for 2
It may be switched to a stage. In other words, the configuration is such that the first step is switched when the button is lightly pressed (pen-up state), and the second step is switched when the button is pressed more strongly (pen-down state). In this case as well, regardless of the dominant arm. It is possible to realize the input pen 21 which is easy to use.

By the way, in the above description, the cycle (sampling cycle) of the drive signal is made different between the first and second drive modes of the vibrator 25, but the cycle is the same and the modulation form of the drive signal is changed. Different, eg first
The drive signal may be modulated into the waveform indicated by reference numeral 902 in FIG. 12 in the drive mode of FIG. 12, and may be modulated into the waveform indicated by reference numeral 906 in the second drive mode. Here, the drive signal 906 is assumed to generate the pulse of the drive signal 902 twice in the period Pt.

As a result, the ultrasonic detection signals of the ultrasonic sensors 6a to 6d on the apparatus body side become the signal 903 in the first drive mode and the signal 907 in the second drive mode.
For example, a peak hold circuit is used to detect the peaks of the envelopes 904 to 908 of the detection signals 903 to 907, and the peak detection signals 905 to 909 are generated, whereby the first and second drive modes can be discriminated.

The frequency of the sound wave to be radiated may be changed by changing the pulse width (frequency) of the drive signal such as 902 or 920 depending on the first and second drive modes of the vibrator 25. . As a result, the ultrasonic sensor 6
The detection signals a to 6d have different frequencies such as 903 or 921, and by detecting the pulse period T of the signal (only one signal 922 is shown) obtained by comparing it with the zero level, It is also possible to distinguish between the second drive modes.

Further, in the first and second drive modes, the optical transmitter / receiver circuit 2 has different modulation modes of the optical signal as the start signal transmitted (emits) from the light emitting element 22.
Alternatively, the optical signal may be detected to distinguish between the first and second drive modes.

However, the drive signal explained second is 90
The modulation method such as 2 or 906 is affected by the reflected wave shown in FIG. That is, even if the drive signal of the vibrator 25 is the drive signal 902 in the first drive mode, the waveform of the ultrasonic detection signal of the ultrasonic sensors 6a to 6d is in the second drive mode due to the influence of the reflected wave. It may have a waveform like the corresponding ultrasonic detection signal 907. That is, the direct wave first reaches the ultrasonic sensors 6a to 6d, and then the reflected wave arrives according to the path difference between the direct wave and the reflected wave. When the wavelength is an integral multiple, the signals of the both may be superimposed, and the first and second peaks may be formed in the waveform of the sound wave detection signal as shown by the signal 907.

Therefore, in this case, although the detection signal 907 is formed by the influence of the reflected wave in the first drive mode,
It is impossible to distinguish whether the detection signal 907 is obtained because the drive signal is set to the signal 906 in the second drive mode. In order to distinguish this, for example, the period Pt of the pulse of the peak detection signal 909 is monitored, and the path difference between the direct wave and the reflected wave detected by each of the ultrasonic sensors 6a to 6d is different, so that all the sensors are detected. It is necessary to perform processing such as determination by comparing the signals of.

Considering the influence of such a reflected wave, the first
And the second drive mode, the drive frequency is made to be different (modulated by the signal 9 instead of modulating the drive signal as 902 or 906).
02 and 920), and the driving cycle described first, that is, the method of changing the sampling cycle is an excellent method in which the influence of the reflected wave can be ignored.

Next, the output coordinate mode will be described.

As described above, the pen side switch 42
By operating a and 42b, even if the input pen 21 is away from the surface of the screen 8 serving as a coordinate input surface, coordinates are input and the cursor is moved (pen-up state) or writing is performed. (Pen-down state) In such a case (when the input pen 21 is not in contact with the surface of the screen 8 and the pen tip switch 41 is off), when the coordinate input operation is performed by the input pen 21 relatively near the screen 8. Operationally required specifications differ between (hereinafter referred to as proximity input) and when coordinate input operation is performed at a considerable distance from the screen 8 (hereinafter referred to as remote input).

First, in the case of proximity input, the distance between the screen 8 constituting the display surface and the input pen 21 in the Z-axis direction is a relatively small value, and when the input pen 21 is moved, it is displayed on the screen 8, for example. Intuitive cursor
Moreover, it is possible to directly move to a desired position. Of course, the actual positional deviation of the cursor with respect to the desired position is larger than that when the cursor is directly input on the surface of the screen 8 (the pen tip switch 41 is in the ON state), but it can be said to be within a practical range.

However, in the case of remote input, it is clear that the shift amount becomes large. For example, in order to move the displayed cursor to a desired position, the operator first intuitively inputs coordinates. However, the amount of deviation from the desired position is large, and while visually recognizing the amount of deviation, the input pen 21 is gradually moved to gradually move the cursor position to the desired position. . In other words, by intuitively first locating the input pen 21 at a desired position and visually recognizing the response (for example, the display position of the cursor), the human brain instructs the hand to perform a position correcting operation, and the cursor is accompanied by the operation. Is gradually moved to move the cursor to a desired position, that is, the loop in which the brain of the operator performs a correction operation based on the visual information by the operator is repeated to achieve the purpose.

As described above, when an operator intends to perform some remote input operation on the image information displayed on the screen 8 (image information having a coordinate system on the XY plane), the operator performs a series of coordinate input. The coordinate value of the first point at the time of attempting to do so and the coordinate value of the above-mentioned image information cannot be matched. This means that a laser pointer is widely used as a tool for pointing an arbitrary point on a display image displayed by OHP or the like. Obviously, it is possible to irradiate the laser to a desired position by performing a position correction operation while observing the point position indicated without understanding.

Now, assuming a normal presentation, meeting, etc. using this laser pointer, it is difficult for the operator to directly indicate the desired position, and from the listener's point of view, the instruction of the laser pointer is given. The position moves discontinuously and suddenly, so I was concerned about finding the indicated position (I searched even when the pointer was not illuminated), and it is a sufficient specification as a tool to help understand the presentation content. Is not.

On the other hand, the pointing rod can be said to be a classic tool for pointing a desired position, but from the listener's point of view, the operation of the pointing rod by the operator can be visually predicted, and the pointing device can be announced rather than the pointing means by the laser pointer. It's a good tool in that you can focus on the content. However, since there is a limit to the length of the pointing rod, the drawback is that the operating range is limited.

In order to solve such a problem, in the coordinate input device of this embodiment, the mode of the input operation by the input pen 21 is divided into the direct input mode, the proximity input mode, and the remote input mode as described above, The output coordinate mode is the absolute coordinate mode in the direct input mode and the proximity input mode, and the relative coordinate mode in the remote input mode.

The switching of the output coordinate mode is performed by the microcomputer 31 of the arithmetic control circuit 1 in the control procedure shown in the flowchart of FIG. 13 as follows.

That is, first, the process is started in step S301. Here, it is determined whether the coordinate input operation is continuously performed in the remote input mode at the above-described sampling cycle, for example, 50 times / second to 40 times / second. The flag shown is initialized to 0 (indicating that the coordinate input operation is not continuously performed).

Next, in step S302, an effective signal necessary for coordinate calculation, that is, an effective start signal, and each ultrasonic sensor are obtained within the above-described sampling cycle (the longer cycle when there are two). It is determined whether an effective ultrasonic wave detection timing signal generated from the detection signals 6a to 6d has been received, and if not, step S312.
Then, the flag is reset to 0, and then the process ends (step S313).

On the other hand, when a valid signal is received in step S302, it is determined in step S303 whether it is in the pen-down state or the pen-up state. That is, it is determined whether the drive mode of the vibrator 25 described above is the first drive mode or the second drive mode. As described above, this determination is performed by detecting the sampling period, frequency, or modulation form of the drive signal, or the modulation form of the start signal, which varies depending on the drive mode.

Next, in step S304, the position of the transducer 25 is determined based on the ultrasonic wave transmission time data to the ultrasonic sensors 6a-6d latched by the latch circuits of the counters 32a-32d at that time. That is, the value of the three-dimensional coordinates (x, y, z) of the input point is calculated by the above-described calculation method.

Next, at step S305, the flag is set to 1
If it is 1, that is, if the coordinate input operation is continuously performed in the remote input mode, the process proceeds to step S311. If not, the process proceeds to step S306.

In step S306, step S304
It is determined whether or not the Z coordinate value among the coordinate values calculated in step 1 is a first predetermined value, for example, 300 mm or less, and if it is less than or equal to the predetermined value, the proximity input mode is recognized, and step S
Proceeding to 307, the output coordinate mode is set to the absolute coordinate mode, and the three-dimensional coordinates (x, y,
The data of x coordinate and y coordinate in z) is output as it is,
Then, the process ends. Here, the z coordinate data may also be output. In the direct input mode, z = 0 is detected by turning on the pen tip switch 41. Therefore, at this time also, the x coordinate and y coordinate data are output as they are.

On the other hand, in step S306, the z coordinate value is the first
If it is determined that it is not less than the predetermined value of step S3,
At 08, it is determined whether or not the z coordinate value is a second predetermined value or more, for example, 1000 mm or more. If it is not the predetermined value or more, the processing is ended, but if it is the predetermined value or more, step S
Proceed to 309.

In step S309, the remote input mode is determined, and the three-dimensional coordinates (x,
The data of the values of the x coordinate and the y coordinate of (y, z) are stored in the memory as coordinate values (X1st, Y1st). afterwards,
After the flag is set to 1 in step S310, the process returns to step S302 and the processes in and after step S302 are repeated.

Here, similarly to the above, the effective signal is detected in step S302, the pen-up / down state is determined in step S303, and the three-dimensional coordinates (x, y,
z) is calculated and whether or not the flag is 1 is determined in step S305. In the case of repeating from step S310, the flag is 1 in step S305. In this case, in the remote input mode, it is recognized that the coordinate input operation is continuously performed, and the process proceeds to step S311.

In step S311, step S304.
The three-dimensional coordinate values calculated in step 1, that is, the x-coordinate value and the y-coordinate value of the three-dimensional coordinate values obtained in this sampling,
In step S309, the x-coordinate value X1st and the y-coordinate value Y1 stored in the memory in the previous sampling are stored.
Calculates and outputs the difference (Δx, Δy) from st. In addition,
Here, x of the three-dimensional coordinate values obtained by this sampling
Re-create the data of coordinate value and y coordinate value, x coordinate value X
It is stored in the memory as data of 1st and y coordinate value Y1st. After that, the process returns to step S302, and step S
The processing from step 302 onward is repeated.

Note that after step S307, when the determination in step S308 is NO, and in step S312.
After that, the processing is ended, but thereafter, this processing is restarted. In the case of No in step S308 and in the case of after step S312, it may be restarted after an appropriate time, but in the case of after step S307, it is necessary to restart immediately.

With the above processing, absolute coordinates (x, y) can be output for direct input and proximity input, and relative coordinates (Δx, Δy) can be output for remote input. As a result, the operator can smoothly move the cursor from the current position of the cursor to a desired position during remote input, and the coordinate input can be performed continuously. During the period, the amount of movement of the cursor in the X direction and the amount of movement of the Y direction absolutely correspond to the amount of movement in both directions of the input pen 21 in a one-to-one relationship, so even if the remote control It is also possible to input.

By the way, according to the coordinate information of one axis (in the above, the Z axis) of the calculated three-dimensional coordinates, the remaining 2
Although the output form of the coordinate information of the axis (above X axis and Y axis) is made different, the switch operation similar to clicking a mouse button is performed according to the coordinate information of one axis (for example, Z axis). It can also be done. For example, in a continuous coordinate input operation that can be determined by a flag, when the input pen 21 is rapidly moved from the arbitrary position in the Z-axis direction and then quickly returned to the original position, it is equivalent to a mouse click. It is determined that the operation was performed. If the operation is repeated twice, it is determined that the double click has been made.

The determination of such a switch operation is performed by the abrupt change of the z coordinate value out of the three-dimensional coordinates calculated by the coordinate input device, and this switch operation can be used for remote operation of the display screen, for example. it can. It is also possible to use this switch operation method and the above-mentioned output coordinate mode switching method together.

As described above, according to the coordinate information of one axis (for example, Z axis), the output form of the coordinate information of the other two axes (for example, X axis and Y axis) is changed, or the mouse click operation is performed. The configuration for performing the same processing as in (4) is not limited to the aerial ultrasonic coordinate input device, but can be applied to other systems capable of detecting three-dimensional coordinates, for example, an optical coordinate input device. .

[0135]

As is apparent from the above description, according to the present invention, in the ultrasonic coordinate input device, the ultrasonic detection signal of the ultrasonic detecting means is processed to generate the ultrasonic detection timing signal. By devising the configuration of the circuit, even if it is not possible to secure a large difference in the transmission path between the direct wave of the ultrasonic wave and the reflected wave from the input point of the coordinates to the ultrasonic wave detecting means,
The influence of the reflected wave can be eliminated or reduced, and the influence of the level fluctuation of the ultrasonic detection signal can be eliminated or reduced, whereby stable and highly accurate coordinate calculation can be performed, and the device The excellent effect that the degree of freedom in designing is also obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a coordinate input device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of an input pen and an ultrasonic sensor of the apparatus, a state of ultrasonic wave transmission, and the like.

FIG. 3 is a block diagram showing a configuration of an arithmetic control circuit of the device.

FIG. 4 is an ultrasonic sensor 1 of a sensor signal processing circuit of the device.
It is a block diagram which shows the structure for each.

FIG. 5 is a timing chart showing waveforms and timings of respective signals related to signal processing of the sensor signal processing circuit.

FIG. 6 is an explanatory diagram illustrating a method of calculating two-dimensional coordinates of an input point.

FIG. 7 is a graph showing a relationship between a distance between an input point and an ultrasonic sensor and a measurement error as a result of an experiment conducted in the configurations of the embodiment and the conventional example.

FIG. 8 is an explanatory diagram showing a three-dimensional coordinate system for inputting coordinates with the coordinate input device according to the second embodiment of the present invention.

9A and 9B are a side view and a rear view showing the appearance of the input pen of the same device.

FIG. 10 is a table showing a correspondence relationship between various modes of the apparatus and ON / OFF of each switch of the input pen and a calculated value of z coordinate.

FIG. 11 is a flowchart showing a processing procedure of switching the drive mode of the vibrator of the input pen according to ON / OFF of each switch of the input pen.

FIG. 12 is a timing chart showing how the modulation mode and frequency of the drive signal for the vibrator are changed according to the drive mode.

FIG. 13 is a flowchart showing a control procedure of a microcomputer of an arithmetic control circuit relating to switching of output coordinate mode.

[Explanation of symbols]

1 Operation control circuit 2 Optical transceiver circuit 3 Signal processing circuit 4 Host device 5 Image projection device 6a to 6d ultrasonic sensor 8 screen 9 Sensor signal processing circuit 21 Input pen 25 oscillators 31 Microcomputer 32a to 32d counter 41 Pen tip switch 42a, 42b Pen side switch 402 Envelope detection circuit 404 Envelope fourth-order differentiation circuit 405 Differential signal comparator 406, 407 Gate signal generation circuit 408 bandpass filter 409 slice circuit 410 Phase signal comparator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuichiro Yoshimura             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F term (reference) 5B068 AA04 AA32 BB21 BC03 BD02                       BD11 BD22 BD25 BE03 BE06                       BE15 CC11 EE04 EE06

Claims (5)

[Claims] 1. A plurality of ultrasonic waves emitted from said ultrasonic wave generating means when a coordinate input point indicating means is provided with ultrasonic wave generating means and a plurality of ultrasonic waves are arranged at different positions. In the coordinate input device that detects the ultrasonic wave by the ultrasonic wave detecting means and calculates the coordinates of the input point based on the detection timing, an envelope signal corresponding to the envelope of the signal from the ultrasonic wave detecting signal output by the ultrasonic wave detecting means. Envelope detecting means for taking out, differentiating means for differentiating the envelope signal by four or more levels and outputting a differential signal, and generating a first gate signal that is valid only while the signal level of the envelope signal exceeds a predetermined threshold level. Comparing the differential signal and the first gate signal with the first gate signal generating means for performing the ultrasonic detection. First detection timing signal generation means for generating a first detection timing signal indicating ultrasonic detection timing detected from the signal envelope, and a second gate which is effective only while the first detection timing signal is effective Second gate signal generating means for generating a signal, phase signal generating means for generating a phase signal indicating the phase of the signal from the ultrasonic detection signal, comparing the second gate signal with the phase signal, It has a 2nd detection timing signal generation means which generates the 2nd detection timing signal which shows the ultrasonic detection timing detected from the phase of the above-mentioned ultrasonic detection signal based on the comparison result, The 1st and 2nd detection A coordinate input device, wherein the coordinate of the input point is calculated based on each of the ultrasonic wave detection timings based on the timing signal. 2. The first detection timing signal is a signal which is valid only while the waveform of the differential signal is below a zero level while the first gate signal is valid. The coordinate input device according to item 1. 3. The coordinate input device according to claim 2, wherein the first valid time of the first detection timing signal is an ultrasonic wave detection time point detected from the envelope of the ultrasonic wave detection signal. . 4. The coordinate input device according to claim 1, wherein the second detection timing signal is a signal corresponding to a portion of the phase signal while the second gate signal is valid. . 5. The coordinate input device according to claim 4, wherein the first valid time of the second detection timing signal is an ultrasonic wave detection time point detected from the phase of the ultrasonic wave detection signal. .