JP2002079792A - Electronic black board device and method for calculating coordinate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize pen input with simple constitution, being inexpensive and being highly accurate. SOLUTION: An electronic black board body is provided with a vibration transmitting plate 8 consisting of an aluminum enamel black board, a vibration- deadening material 7 for preventing vibration reflected on the outer peripheral end face from returning to the central part and vibration sensors 6a-6d set in the neighborhood of the boundary of the vibration transmitting plate 8 and the vibration-deadening material 7. The electronic black board main body is connected with a signal wave detecting circuit 4 for outputting a signal for a fact that the vibration is detected by means of the vibration sensors 6a-6d to an operation controlling circuit 1 and is provided with the operation controlling circuit 1 for controlling the whole device and operating the coordinate position of a vibration inputting point, a photo-detecting circuit 2 for detecting optical signals emitted from light emitting devices 22, 10 and 12 of vibration inputting pens 21, 9 and 11 and an eraser 13 and a signal processing circuit 3 for processing the optical signals detected by the photo-detecting circuit 2 and generating a start timing signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic blackboard device, and more particularly, to the input of characters, graphics, etc. on a whiteboard by means of a feltven or the like, and the input contents are electrically transmitted as drawing signals for processing. And an electronic blackboard device capable of printing.

[0002]

2. Description of the Related Art There is known an electronic blackboard device which is a whiteboard used in a meeting such as a conference or a meeting, and which can print out the contents handwritten by a marker pen. This type of electronic blackboard device can be roughly classified into two types. First, it is possible to optically scan the content input by handwriting on a whiteboard, print it, save it as image data, and browse it. thing,
Secondly, some of the input contents can be transferred to a personal computer or the like as electronic data at the same time as being drawn on the whiteboard.

In the second method, the screen of a personal computer is projected by a projector on a whiteboard also serving as a screen, and the personal computer can be operated with a pen in the same manner as a mouse. It is also possible to input characters and figures for the displayed data. This method differs from the method of scanning and taking in characters and figures drawn with a marker on the entire surface of the board, so that real-time coordinate data can be transferred. It is possible to hold a meeting in real time.

As a method for detecting pen input data on a whiteboard, a pressure-sensitive method and an electromagnetic induction method are known. In the pressure-sensitive method, pressure on an input surface is sensed and output as coordinate data, and a film serving as a sensor is formed on the input surface, so that the apparatus can be constructed relatively inexpensively. The electromagnetic induction system has a configuration in which a magnetic field is generated between the input pen and the input plate.The input pen has a built-in coil, and the input plate has loop sensor lines printed in a matrix and has high accuracy. Can output the coordinates.

[0005]

The system for detecting pen input data in the above-mentioned conventional electronic blackboard device has the following problems.

[0006] In the pressure-sensitive system, since the pen directly contacts the resistance sheet and the input is repeatedly executed, the surface is easily scratched and has a problem in durability. In addition, since the uniformity of the resistance sheet affects the coordinate calculation accuracy, a relatively large resistance sheet used in an electronic blackboard device in particular must be expensive. Further, there is a problem that it is difficult to improve the coordinate calculation accuracy.

On the other hand, in the electromagnetic induction system, since the input plate itself is a sensor plate, in order to form a large input surface, the number of sensors increases and, at the same time, a signal for each sense line is amplified. The number of electronic circuits and the like for performing the operation increases. Therefore, there has been a problem that it becomes very expensive and the structure becomes complicated.

The present invention has been made in view of such a problem, and an object of the present invention is to provide an electronic blackboard apparatus which has a simple configuration, is inexpensive, and realizes highly accurate pen input. is there.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a vibration transmission plate for transmitting elastic wave vibration, and the vibration transmission plate having the elastic transmission plate. Vibration input means for inputting wave vibration, vibration detection means provided on the outer edge of the vibration transmission plate for detecting the elastic wave vibration, and the elastic wave vibration from the vibration input means reaching the vibration detection means Coordinate calculation means for calculating a coordinate position of the vibration input means on the vibration transmission plate according to time.

According to a second aspect of the present invention, in the first aspect, the vibration input means includes a light emitting element driving means for outputting the optical signal at the same time as inputting the elastic wave vibration to the vibration transmission plate. The coordinate calculation unit has a light detection unit that receives the optical signal, and a signal processing unit that generates a start timing signal in accordance with the optical signal, and the start timing signal generated by the signal processing unit is In response, timing of the arrival time is started.

According to a third aspect of the present invention, the signal processing unit according to the second aspect reproduces a pulse train included in the optical signal to generate a pulse signal, and generates an envelope signal from the pulse train. And a means for generating a gate signal based on the envelope signal, and means for generating the start timing signal from the pulse signal and the gate signal.

According to a fourth aspect of the present invention, the coordinate calculating means according to the second aspect detects a group signal of the elastic wave vibration detected by the vibration detecting means to generate a vibration arrival timing signal. Signal detecting means for terminating the arrival time in response to the vibration arrival timing signal.

According to a fifth aspect of the present invention, the coordinate calculation means according to the second aspect detects a phase signal of the elastic wave vibration detected by the vibration detection means and generates a vibration arrival timing signal. Signal detecting means for terminating the arrival time in response to the vibration arrival timing signal.

According to a sixth aspect of the present invention, the coordinate calculating means according to any one of the first to fifth aspects comprises a plurality of the vibration detecting means provided on an outer edge of the vibration transmitting plate. The coordinate position is calculated by selecting at least two of the vibration input means.

According to a seventh aspect of the present invention, in the coordinate calculation means according to any one of the first to fifth aspects, among the plurality of the vibration detecting means, three of the vibration detecting means having a short arrival time are used. The coordinate position is calculated by selecting a detecting means.

According to an eighth aspect of the present invention, the coordinate calculating means according to the fourth or fifth aspect selects a reference vibration detecting means from among the plurality of vibration detecting means, and selects the reference vibration detecting means. The coordinate position is calculated according to a time difference between the vibration arrival timing signals of the detection means and the other vibration detection means.

According to a ninth aspect of the present invention, the vibration input means according to any one of the first to eighth aspects includes means for directly drawing ink on the vibration transmission plate with ink. And

According to a tenth aspect of the present invention, the vibration input means according to any one of the first to ninth aspects further comprises means for erasing contents drawn directly with ink on the vibration transmission plate. It is characterized by having.

According to an eleventh aspect of the present invention, the elastic wave vibration input to the vibration transmission plate by the vibration input means is detected by the vibration detection means provided at the outer edge of the vibration transmission plate, and the vibration from the vibration input means is detected. A coordinate position of the vibration input means on the vibration transmission plate is calculated according to a time required for the elastic wave vibration to reach the vibration detection means.

According to a twelfth aspect of the present invention, in the eleventh aspect, a light detecting step of inputting the elastic wave vibration to the vibration transmission plate and simultaneously detecting an optical signal output from the vibration input means, And a signal processing step of generating a start timing signal in response to a signal, wherein timing of the arrival time is started in response to the start timing signal.

According to a thirteenth aspect of the present invention, in the signal processing step of the twelfth aspect, the envelope signal is generated from a pulse signal obtained by reproducing a pulse train included in the optical signal, and the envelope signal. And generating the start timing signal from a gate signal generated based on the above.

According to a fourteenth aspect of the present invention, the method according to the twelfth aspect, further comprising a group signal detecting step of generating a vibration arrival timing signal by detecting a group signal of the elastic wave vibration detected by the vibration detecting means. The timing of the arrival time is terminated in response to the vibration arrival timing signal.

According to a fifteenth aspect of the present invention, in the twelfth aspect, there is provided a phase signal detecting step of detecting a phase signal of the elastic wave vibration detected by the vibration detecting means and generating a vibration arrival timing signal, The timing of the arrival time is terminated in response to the vibration arrival timing signal.

According to a sixteenth aspect of the present invention, in any one of the eleventh to fifteenth aspects, the coordinate position is calculated by selecting at least two of the vibration input means from among the plurality of vibration detection means. It is characterized by the following.

According to a seventeenth aspect of the present invention, in any one of the eleventh to fifteenth aspects, among the plurality of vibration detecting means, three of the vibration detecting means having a short arrival time are selected. It is characterized in that a coordinate position is calculated.

The invention according to claim 18 is the invention according to claim 14 or 15, wherein a reference vibration detecting means is selected from the plurality of vibration detecting means, and the reference vibration detecting means and the other vibration detecting means are selected. The coordinate position is calculated according to a time difference between the vibration arrival timing signal and a detection means.

[0027]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a diagram showing the overall configuration of an electronic blackboard device according to the present invention. The electronic blackboard body is
A vibration transmission plate 8 composed of an aluminum enameled blackboard coated with a glass film on an aluminum-plated steel plate, and vibrations provided on the outer periphery of the vibration transmission plate 8 that are prevented from returning to the center at the peripheral end face of the vibration transmission plate (attenuation). 7) Anti-vibration material 7
Installed near the boundary between the vibration transmission plate 8 and the vibration isolating material 7,
It comprises vibration sensors 6a to 6d for converting mechanical vibration of a piezoelectric element or the like into an electric signal.

The electronic blackboard body includes vibration sensors 6a to 6d.
A signal waveform detection circuit 4 for outputting a signal indicating that vibration has been detected to the arithmetic and control circuit 1 to control the entire apparatus and calculate the coordinate position of the vibration input point; Pens 21, 9, 11 and eraser 1
3, a light detection circuit 2 for detecting light signals emitted from the light emitting elements 22, 10 and 12, and a light input signal detected by the light detection circuit 2 to generate a start timing signal to be described later. And a signal processing circuit 3 for detecting attributes of the eraser 13, 9, 11.

The vibration input pens 21, 9, 11 and the eraser 13 are provided independently of the electronic blackboard device. The vibration input pens 21, 9, and 11 can draw with different colored markers, respectively, and can input ultrasonic vibration to the vibration transmission plate 8. Eraser 1
Numeral 3 is used to erase figures and characters drawn by the marker, and can input ultrasonic vibrations to the vibration transmission plate 8 in the same manner as the vibration input pens 21, 9 and 11. The input of the ultrasonic vibration is performed by touching the effective input area 5 shown in FIG. 1 with the vibration input pens 21, 9, 11 and the eraser 13.

With such a configuration, the vibration input pens 21, 9, 11 or the eraser 13 as the vibration input means are provided.
Is touched in the effective input area 5 of the vibration transmission plate 8, the vibration generated by the vibration input pen 21 or the eraser 13 is delayed by the vibration sensors 6a to 6d according to the distance to the vibration sensors 6a to 6d. To reach. Vibration sensor 6
a to 6d send a signal to the effect that vibration has been detected to the signal waveform detection circuit 4. The signal waveform detection circuit 4 includes a vibration sensor 6
Signals from a to 6d are detected, and a signal indicating the timing of arrival of vibration at each vibration sensor is generated by a waveform detection process described later. The arithmetic control circuit 1 calculates the arrival time of the vibrations from the vibration sensors 6a to 6d based on the signal from the signal waveform detection circuit 4, and calculates the coordinate position of the vibration input pen 21 or the eraser 13. Further, the arithmetic control circuit 1
The calculated vibration input pen 21 or eraser 13
Is output to an external device (not shown) by serial and parallel communication.

The light emitting elements 22, 10, 12 of the vibration input pens 21, 9, 11 or the eraser 13 send out optical signals corresponding to light emission timing signals to be described later. The light detection circuit 2 detects light signals emitted from the light emitting elements 22, 10, and 12, and the detected signals are processed by the signal processing circuit 3. The signal processing circuit 3 includes a vibration input pen 21
Alternatively, a start timing signal indicating the oscillation timing of the vibrator 26 of the eraser 13 is generated, and the arithmetic control circuit 1
Send to

FIG. 2 is a schematic configuration diagram showing an example of the vibration input pen of the electronic blackboard device according to the present invention. Since the vibration input pens 21, 9, and 11 have the same configuration, only the vibration input pen 21 will be described here. Vibration input pen 21
Are a pen tip horn 27 for inputting the ultrasonic vibration of the vibrator 26 to the vibration transmission plate 8, a vibrator 26 for converting an electric drive signal into a mechanical ultrasonic vibration, and a vibration for driving the vibrator 26. And a child drive circuit 25.

With such a configuration, the vibration input pen 2
When 1, 9 and 11 are touched in the effective input area 5 of the vibration transmission plate 8, the vibrator drive circuit 25 sends a drive signal for driving the vibrator 26, and the vibration of the vibrator 26
It is input to the vibration transmission plate 8 via the pen tip horn 27.

Here, the vibration frequency of the vibrator 26 is selected to a value at which a plate wave can be generated on the vibration transmission plate 8. The vibration frequency of the vibration input pen 21 is not limited to a value that generates a plate wave. For example, when a surface wave that propagates through the vibration transmission plate 8 is used as a detection wave, The frequency may be set to a sufficiently high value (a state in which the wavelength λ of the wave propagating through the vibration transmission plate 8 is sufficiently small with respect to the thickness of the plate).

The vibration input pen 21 includes a light emitting element 22 provided at the rear end of the vibration input pen 21 and a light emitting element drive for driving the light emitting element 22 by a light emitting element drive signal obtained by modulating a rectangular pulse signal described later at a predetermined frequency. A circuit 24;
The light emitting element drive circuit 24 is connected to the vibrator drive circuit 25.

With such a configuration, the vibrator driving circuit 2
5 transmits a light emission timing signal to the light emitting element drive circuit 24 simultaneously with driving of the vibrator 26, that is, oscillation. When the light emitting element driving circuit 24 receives the light emitting timing signal, the light emitting element driving circuit 24 drives the light emitting element 22 with a light emitting element driving signal obtained by modulating a rectangular pulse signal to be described later at a predetermined frequency, and the light emitting element 22 emits light corresponding to the light emitting element driving signal. Output a signal.

The type of the light emitting element 22 is selected according to the peak wavelength of the spectral sensitivity of the light receiving element 601 provided in the light detection circuit 2 described later. The modulation frequency of the above-described light emitting element drive signal may be the same as the frequency for driving the vibrator 26 to simplify the circuit.

The vibration input pen 21 in this embodiment is configured to also function as a marker pen that can draw with ink. An ink tank 28 filled with ink and having a pen tip 29 made of a synthetic resin or the like is provided in a cylindrical shape on the outer periphery, and can be drawn on the screen of the vibration transmission plate 8 via the pen tip 29. It has become. Further, a pair of electrodes 281 serving as a sensor for detecting the remaining amount of ink is provided.
And 282 are arranged below the ink tank 28, and the remaining amount of ink can be detected by the resistance value between the electrodes. The ultrasonic vibration generated from the pen tip horn 27 is
The ultrasonic vibration and vibration are incident on the vibration transmission plate 8 with sufficient power even through the pen tip 29 which is a synthetic resin.

The light emitting element driving circuit 24 has an ID indicating the attribute of the vibration input pen set in the memory in the light emitting element driving circuit 24, in addition to the light emitting timing signal described above.
And color information of the ink filled in the ink tank 28,
A signal indicating the remaining amount of ink according to the resistance value detected by the electrodes 281 and 282 can be transmitted in a predetermined format.

The coordinates input by the vibration input pens 21, 9 and 11 are transferred from the arithmetic and control circuit 1 to a host device such as a personal computer (not shown), so that the same coordinate data as the contents drawn with the marker are obtained. Can be processed on the host device side. Further, the host device can be operated by projecting data of the host device onto the vibration transmission plate 8 by a projector or the like.

Power for all circuits in the vibration input pen 21 is supplied by a power supply circuit 23 composed of a battery, a power supply IC, a capacitor, and the like.

FIG. 3 is a schematic diagram showing an example of an eraser of the electronic blackboard device according to the present invention. Eraser 1
Reference numeral 3 denotes a pen point horn 27 for inputting ultrasonic vibration of the vibrator 26 to the vibration transmission plate 8, a vibrator 26 for converting an electric drive signal into mechanical ultrasonic vibration, and driving the vibrator 26. A vibrator drive circuit 25 is provided.

With such a configuration, the eraser 13
Is touched in the effective input area 5 of the vibration transmission plate 8, the vibrator drive circuit 25 sends out a drive signal for driving the vibrator 26, and the vibration of the vibrator 26 is transmitted via the nib horn 27. Is input to the vibration transmission plate 8.

The eraser 13 includes a light emitting element 22 provided at the rear end of the eraser 13 and a light emitting element driving circuit 24 for driving the light emitting element 22 with a light emitting element driving signal obtained by modulating a rectangular pulse signal described later at a predetermined frequency. The light emitting element driving circuit 24 is connected to the vibrator driving circuit 25.

With such a configuration, the vibrator driving circuit 2
5 transmits a light emission timing signal to the light emitting element drive circuit 24 simultaneously with driving of the vibrator 26, that is, oscillation. When the light emitting element driving circuit 24 receives the light emitting timing signal, the light emitting element driving circuit 24 drives the light emitting element 22 with a light emitting element driving signal obtained by modulating a rectangular pulse signal to be described later at a predetermined frequency, and the light emitting element 22 emits light corresponding to the light emitting element driving signal. Output a signal.

Further, the light emitting element drive circuit 24 has, besides the light emission timing signal described above, an I which indicates the attribute of the eraser 13 set in the memory in the light emitting element drive circuit 24.
D can be transmitted in a predetermined format.

The eraser 13 is connected to the vibration input pen 2
The content drawn on the screen of the vibration transmission plate 8 by the user 1 can be erased by wiping the content with the synthetic resin 291.

The coordinates input by the eraser 13 are transferred from the arithmetic and control circuit 1 to a host device such as a personal computer (not shown) from the arithmetic control circuit 1 after adding the coordinate value data and flag information indicating that the input is made by the eraser 13. . On the side of the transferred host device, for example, a drawing application can be made to function so as to erase drawing information already drawn in a predetermined rectangular area centered on the detected coordinate value.

FIG. 4 is a block diagram showing an example of a light detection circuit and a signal processing circuit of the electronic blackboard device according to the present invention. The light detection circuit 2 includes a light receiving element 601 including a photodiode or the like and an amplification circuit 602. Light receiving element 601
Since the peak wavelength of the spectral sensitivity is selected in accordance with the light emitting element 22 described above, and a filter for suppressing disturbance light such as a fluorescent lamp is provided outside, the light signal other than the light signal from the vibration input pen 21 is used. With respect to the light having the wavelength of, only a negligible level is detected.

The output signal of the light receiving element 601 having received the optical signal is amplified by the amplifier circuit 602 at a predetermined amplification degree. The amplification degree is set at a detection level necessary for the size of the apparatus, particularly for the distance between the vibration input pen 21 and the light receiving element 601. The amplification circuit 602 sends the amplified detection signal to the signal processing circuit 3.

The signal processing circuit 3 includes a band-pass filter 603 for inputting a detection signal from the light detection circuit 2 and a low-pass filter 604 for generating a gate signal from an output of the band-pass filter 603 in order to generate a start timing signal. A first comparator 605 and a gate signal generation circuit 606; a slice circuit 607 for shaping the output of the band-pass filter 603 to generate a start timing signal; and a second comparator 608
And a start timing signal generation circuit 609 for transmitting a start timing signal to the arithmetic and control circuit 1.
It is composed of The operation will be described later.

FIG. 5 is a timing chart for explaining generation of a start timing signal in the signal processing circuit. FIG. 5A is a diagram for explaining generation of an optical signal output from the light emitting element 22 in response to a light emission timing signal in the vibration input pen 21 (the same applies to the eraser 13; hereinafter, omitted). is there. The vibrator drive circuit 25 in the vibration input pen 21 applies a vibrator drive signal 73 which is, for example, two rectangular pulses to the vibrator 26 to drive the vibrator 26. The vibrator drive circuit 25 transmits a light emission timing signal to that effect to the light emitting element drive circuit 24 at the same time as the driving of the vibrator 26, ie, the oscillation. The light emitting element drive circuit 24 outputs a light emitting element drive signal 71 to the light emitting element 22 and drives the light emitting element 22 at a cycle t1. Here, the cycle t1 is within the effective input area 5 of the vibration transmission plate 8.
A delay time for the vibration to propagate from the vibration sensors 6a to 6d to the farthest point and an interval longer than the time required for signal processing described later are set.

The light emitting element driving signal 72 is an enlarged display of the waveform of the light emitting element driving signal 71. Each rectangular pulse of the light-emitting element drive signal 71 is modulated by a pulse signal of a carrier having a predetermined frequency, and is composed of a pulse train of five pulses as shown in the light-emitting element drive signal 72, for example. The circuit is simplified by setting the modulation frequency of the carrier to be the same as the drive frequency of the vibrator 26.
The time t2 (time interval between blocks of five pulse trains) in the light emitting element drive signal 72 is appropriately set in the photodetector circuit 2 described later according to the first falling and second rising characteristics of the detection signal. Is done.

The light-emitting element drive signal 72 is a drive signal for driving the light-emitting element 22. The light signal output from the light-emitting element 22 driven by the light-emitting element drive signal 72 also corresponds to this. 72 may be regarded as an optical signal.

FIG. 5B is a diagram for explaining generation of a start timing signal in the signal processing circuit 3. The light detection circuit 2 includes a light emitting element 22 of the vibration input pen 21.
Detecting an optical signal corresponding to the light emitting element drive signal 72 from
When the detection signal is input to the signal processing circuit 3, the band-pass filter 603 extracts the modulation frequency component of the carrier of the detection signal. The waveform 74 that has passed through the band-pass filter 603 is input to a low-pass filter 604 in order to extract an envelope signal. The envelope signal 75 that has passed through the low-pass filter 604 is input to the first comparator 605, and its level (voltage level)
Is compared with the level of the reference signal 751. The reference signal 751 is set such that the first waveform of the signal 74 is sufficiently higher than the noise level and is surely higher than the reference signal 741 described later.

The first comparator 605 receives the reference signal 7
A signal 752 indicating whether or not the level of the envelope signal 75 is higher than the reference signal 751 as a comparison result with the reference signal 751
Is output to the gate signal generation circuit 606. The gate signal generation circuit 606 outputs the gate signal 7 corresponding to the signal 752.
53 is generated. Note that the gate signal 753 is the signal 74
The signal 752 has a fixed delay time so that the gate is opened only for the carrier signal of the second block. This delay time is set within the effective input area 5 of the vibration transmission plate 8 to the distance from the vibration sensors 6a to 6d to the nearest point, and is set to be equal to or less than the delay time for the vibration to propagate.

On the other hand, the signal 74 after passing through the band-pass filter 603 is also inputted to the slice circuit 607 and further inputted to the second comparator 608.
The second comparator 608 compares the voltage level of the signal 74 passed through the slice circuit 607 with a reference signal 741 defined by a noise level, and generates a pulse signal 742 corresponding to the light emitting element drive signal (optical signal) 72. Output.

The gate signal 753 and the pulse signal 742 output from the second comparator 608 are input to the start timing signal generation circuit 609. Gate signal 7
A start timing signal 76 indicating the oscillation timing of the vibration input pen 21 is generated by using the second stable pulse of the pulse signal 742 as a detection point while 53 is at the active level (high level). The start timing signal 76 is input to the arithmetic and control circuit 1 and is used as a start timing signal to start measuring the transmission time of the ultrasonic vibration detected by the vibration sensors 6a to 6d.

By detecting the oscillation timing of the vibration input pen 21 in this way, it is more resistant to fluctuations in the level of the detection light and noise than to the detection at the predetermined detection point of the output of the low-pass filter, which is a general detection method. It can be configured. In addition, since the detection can be performed without depending on the rising characteristics of the amplifier circuit 602 and the band-pass filter 603 for amplifying the output signal of the light receiving element 601, the oscillation timing can be detected with high accuracy.
Therefore, since the detection can be performed at a timing that does not depend on the level fluctuation, it can be used as a start timing of timing of coordinate input detection that requires a high-precision absolute time, whereby the coordinates can be calculated with high accuracy.

In the above description, the detection point of the oscillation timing is the second pulse of the pulse signal 742 while the gate signal 753 is at the active level.
Depending on the rising characteristics of the carrier signal 74, the third and subsequent pulses may be used as the detection point, and a point where jitter or the like is small and stable in time may be used as the detection point.

FIG. 6 is a block diagram showing an example of the arithmetic and control circuit of the electronic blackboard device according to the present invention. The arithmetic and control circuit 1 includes a microcomputer 31 for controlling the entire electronic blackboard device. The microcomputer 31
It includes an internal counter, a ROM storing a processing procedure shown in FIG. 12 described below, a RAM used for calculations and the like, and a non-volatile memory storing constants and the like. The arithmetic and control circuit 1 includes counters 32a to 32d for measuring a reference block, a detection signal input circuit 34 for receiving a vibration arrival timing signal, and a determination circuit for determining reception of a vibration arrival timing signal, which is connected to the microcomputer 31. 33
And I / O port 3 which is an interface with an external device
5 is provided.

At the same time when the vibrator 26 is driven by the vibration input pen 21, an optical signal output from the light emitting element 22 is detected by the light detection circuit 2, and a start timing signal generated by the signal processing circuit 3 based on the signal is counted by a counter. 3
Input to 2a to 32d. Counters 32a to 32d
Starts timing by the start timing signal,
The vibration detection by the vibration sensors 6a to 6d is synchronized,
The arithmetic control circuit 1 can measure the delay time until the vibration is detected by the vibration sensors 6a to 6d.

The arrival timing signals of the vibration sensors 6a to 6d output from the signal waveform detection circuit 4 described later are transmitted to the counters 32a to 3d via the detection signal input circuit 34.
2d, and the counters 32a to 32d stop counting. Each of the counters 32a to 32d corresponds to each of the vibration sensors 6a to 6d.

When the determination circuit 33 determines that all the vibration arrival timing signals have been received by the detection signal input circuit 34, it outputs a signal to that effect to the microcomputer 31. When the microcomputer 31 receives the signal from the determination circuit 33, the microcomputer 31 receives the signal from the counters 32a to 32d.
The arrival time of the vibrations from the vibration sensors 6a to 6d is read from the latch circuit, and a predetermined calculation is performed to calculate the coordinate position of the vibration input pen 21 on the vibration transmission plate 8.

By outputting coordinate position information via the I / O port 35, coordinate values can be output to an external device.

FIG. 7 is a block diagram showing an example of the signal waveform detection circuit of the electronic blackboard device according to the present invention. The signal waveform detection circuit 4 includes a preamplifier circuit 401 for amplifying a signal detected by the vibration sensor 6a, a high-pass filter 402 for shaping an output of the preamplifier circuit 401, and an envelope for detecting an envelope from an output of the high-pass filter 402. A detection circuit 403 and an envelope inflection point detection circuit 4 for generating a second-order differential output waveform from the detected envelope
04, a gate signal generation circuit 406 for generating a gate generation signal from the detected envelope and the second derivative output waveform
A monostable multivibrator 407 for generating a gate signal having a predetermined pulse width from the gate generation signal, and a Tg comparator 405 for generating a Tg signal from the second-order differential output waveform and the gate signal and transmitting the signal to the arithmetic and control circuit 1 ing. Further, the signal waveform detection circuit 4 includes a preamplifier circuit 40
1, a band pass filter 408 for shaping the output of the band pass filter 408, a slice circuit 409 for slicing the output of the band pass filter 408 into a waveform having a predetermined amplitude level or less, and a phase delay time signal t based on the output of the slice circuit 409 and the gate signal.
a Tp comparator 410 for generating p and sending it to the arithmetic and control circuit 1.

FIG. 8 is a timing chart for explaining the processing contents in the signal waveform detection circuit. Hereinafter, the case of the vibration sensor 6a will be described, but the same applies to the other vibration sensors 6b to 6d. As described above, in the arithmetic and control circuit 1, the measurement of the vibration transmission time to the vibration sensor 6a is started simultaneously with the output of the start timing signal from the signal processing circuit 3 to the arithmetic and control circuit 1. At this time, the transducer drive signal 51 is applied to the transducer 26 from the transducer drive circuit 25 in the vibration input pen 21. The transducer drive signal 51 is short (for example, 2
(Emitted) rectangular pulse. The ultrasonic vibration transmitted from the vibration input pen 21 to the vibration transmission plate 8 by the vibrator drive signal 51 proceeds over a time corresponding to the distance to the vibration sensor 6a, and then forms a short detection waveform as the vibration sensor 6a.
Is detected by The reason why the oscillator drive signal 51 is set to a short pulse is to prevent erroneous detection due to interference (superposition) between the unnecessary reflection component mainly at the end face of the vibration transmission plate 8 and the vibration to be detected, and to reduce the size of the entire apparatus. That's why.

The signal waveform 52 obtained by the vibration sensor 6 a detecting the ultrasonic vibration transmitted from the vibration input pen 21 to the vibration transmitting plate 8 by the vibrator driving signal 51 has a signal waveform 52.
After being amplified at 01, respective processes are performed on the group signal 521 and the phase signal 522.

The group signal 521 is processed by processing the signal after passing through the high-pass filter 402 in order to remove unnecessary vibration. Since the processing of the group signal 521 is easily affected by the reflected wave, the short detection signal after passing through the high-pass filter 402 is used only for envelope detection.

The envelope 53 is extracted by the envelope detection circuit 403 from the detection signal after the signal waveform 52 detected by the vibration sensor 6 a has passed through the high-pass filter 402. The extracted envelope signal 53 is input to the gate signal generation circuit 406. The gate signal generation circuit 406 attenuates the input envelope signal 53 to an appropriate amplitude and generates a reference level signal 531 to which a certain offset is added. Gate signal generation circuit 406
, The second-order differential output waveform 54 is also input by the envelope inflection point detection circuit 404, and the second-order differential output waveform 54 is compared with the reference level signal 531 to output a gate generation signal 55.

The monostable multivibrator 407 outputs a gate signal 56 having a predetermined pulse width to the Tg comparator 405 and the Tp comparator 410 from the rising timing of the input gate generation signal 55.

The Tg comparator 405 outputs the gate signal 5
6 and the second-order differential waveform 54 are input, and a tg signal 59 is generated using the zero-cross point while the gate signal 56 is open as the inflection point of the envelope. The obtained tg signal is supplied to the arithmetic and control circuit 1 as a vibration arrival timing signal.

The phase signal 522 is obtained by shaping the output of the preamplifier circuit 401 into a signal of a frequency component having a predetermined width by a narrow band-pass filter 408, and further slicing the waveform to a predetermined amplitude level or lower by a slicing circuit 409. (Waveform level compression) to obtain a slice output 57. When the slice output 57 and the gate signal 56 are input to the Tp comparator 410, the Tp comparator 410
Generates a phase signal 58 of the slice output 57 while the gate signal 56 is at the active level. The Tp comparator 410 detects a zero-cross point of a rising edge in a predetermined order, generates a phase delay time signal tp, and supplies the signal to the arithmetic and control circuit 1 as a vibration arrival timing signal. In the example of FIG. 5, tp is the second rising zero-crossing point.

Here, the reference level signal for outputting the gate generation signal 56 may be a variable level synchronized with the drive pulse 51 in accordance with the distance between the vibration input pen 21 and the vibration sensor 6a. When the variation width is large, the detection point is stabilized by setting the variable level, which is more effective.

Next, detection of the distance between the vibration input point and the vibration sensor will be described. Since the vibration used in the electronic blackboard device of the present embodiment is a plate wave, the relationship between the group signal 521 and the phase signal 522 of the detected waveform is related to the transmission distance in the vibration transmission plate 8 during the transmission of the vibration. , Depending on the transmission distance. Here, the traveling speed of the group signal 521, that is, the group velocity is Vg, and the traveling speed of the phase signal 522, that is, the phase velocity is Vp. The distance between the vibration input pen 21 and the vibration sensor 6a can be detected from the group velocity Vg and the phase velocity Vp.

Focusing only on the group signal 521, the speed is Vg. When a point on a specific waveform (for example, an inflection point) is detected, the vibration input pen 21 and the vibration sensor 6
The distance between “a” is given by d = Vg · tg (1), where tg is the vibration transmission time. Equation (1) relates to one of the vibration sensors 6a, but the distance between the other three vibration sensors 6b to 6d and the vibration input pen 3 can be similarly expressed by the same equation.

In order to determine coordinates with higher accuracy, processing based on the detection of the phase signal 522 is performed. Phase signal 52
The distance between the vibration sensor and the vibration pen is obtained from d = n · λp + Vp · tp (2) based on tp detected from 2 as described above. Here, λp is the wavelength of the elastic wave, and N is an integer.
From the expressions (1) and (2), the above integer n is as follows: n = int [(Vg · tg−Vp · tp) λp / + ／] (3)

As described above, since the plate wave is used as the detection wave, the linearity of the group delay time tg with respect to the distance is not good.
A necessary and sufficient condition for obtaining an accurate integer n is given by the following equation (4).
Equation (5) derived from n * = (Vg · tg−Vp · tp) / λp (4) ΔN = n * −n ≦ 0.5 (5) If the generated error is within ± １ ／ wavelength, the group delay time tg This indicates that the integer n can be accurately determined even if the linearity is not good. By substituting the determined n into equation (2), the vibration input pen 2
1 and the distance d between the vibration sensor 6a can be accurately measured. The circuit described above is for the vibration sensor 6a, and the same circuit is provided for other vibration sensors.

FIG. 9 is a diagram for explaining a coordinate calculation method in the electronic blackboard device according to the present invention. Four vibration sensors 6a to 6d are provided near the vertexes of the four sides on the vibration transmission plate 8.
Are provided at the positions of the symbols Sa to Sd. Based on the principle described above, the linear distances da to dd from the position P of the vibration input pen 21 to the positions of the vibration sensors 6a to 6d can be obtained. The linear distances da to dd are calculated by the arithmetic control circuit 1.
, The coordinates (x, y) of the position P of the vibration input pen 3 can be obtained from the theorem of three squares as follows. x = (da + dd) · (da−dd) / 2X (6) y = (da + db) · (da−db) / 2Y (7) where X and Y are the distance between the vibration sensors 6a and 6d, respectively, and the vibration sensor This is the distance between 6a and 6b, and the position coordinates of the vibration input pen 21 can be detected in real time as described above.

In the above calculation, the calculation is performed using the distance information da, db, and dd to the three vibration sensors.
In this embodiment, four vibration sensors are provided, and the remaining vibration sensors are used to verify the certainty of the coordinates (x, y) of P using the distance information dc. For example,
The distance information of the vibration sensor having the largest distance L between the vibration input pen 21 and the vibration sensor (the detection signal level is reduced because the distance L is increased and the probability of being affected by noise is increased) is not used, and the remaining information is not used. The coordinates may be calculated by three vibration sensors. In this embodiment, four vibration sensors 6 are used.
a to 6d are arranged and the coordinates are calculated by three vibration sensors. However, geometrically, the coordinates can be calculated by two or more vibration sensors. It goes without saying that it is set.

Embodiment 2 In Embodiment 1, the optical signal from the vibration input pen 21 was used as a start timing signal for measuring the delay time of the ultrasonic vibration detected by the vibration sensor. In the present embodiment, the light signal from the vibration input pen 21 is used for the process of obtaining the certainty of the coordinates, and the coordinates are calculated using the difference data of the time data detected by each vibration sensor. Will be described. In the coordinate calculation based on the difference data, a vibration sensor serving as one reference is determined, and a coordinate value is calculated from a time difference from the vibration sensor. A different vibration sensor is used for each region as a reference vibration sensor.

FIG. 10 is a diagram showing an example of a method for dividing the area of the coordinate input surface for calculating the coordinates. The boundaries of the regions in FIG. 10 are divided at the midpoints of the sensors facing each other. For example, the boundary between the position Sa of the vibration sensor 6a and the position Sc of the vibration sensor 6c is a boundary that divides the regions 8, 1, 2, and 3 from the regions 7, 6, 5, and 4.

FIG. 11 is a diagram showing an example of a method for defining a difference from the reference vibration sensor in each region in FIG. In each area, the difference from the reference sensor is term
0, 1, and 2, and the sign of the x and y coordinates in that area is defined as snx and sny.

[0085]

(Equation 1)

The above equation has a different calculation order depending on the region. In the regions 2, 3, 6, and 7, x0 is first calculated using Expression (8). Substituting the obtained x0 into equation (11),
Get yn coordinates. Here, since the obtained x and y coordinates have low accuracy, the obtained yn is further substituted into Expression (10) to calculate xn. This is repeated three times to converge the data. Similarly, in the regions 1, 4, 5, and 8, the calculation is performed from Expression (9), and the calculation is repeatedly performed in the same manner as Expressions (10) and (11).

Next, the certainty of the obtained coordinates is calculated. For the certainty of the coordinates, the distance to each sensor is calculated back from the obtained coordinate value, and if there is no difference between the distance and the measured distance, the coordinate value can be regarded as correct. The determination is performed by the number of vibration sensors arranged on the vibration transmission plate 8, and in the present embodiment, there is 4 cm. If the values are different from each other, it is determined that a detection error is included, and no data is output. At this time, the distance data serving as a comparison reference is data using a timing start timing signal based on an optical signal.

FIG. 12 is a flowchart showing a processing procedure from acquisition of difference time data to output of coordinates. First, the arithmetic control circuit 1 is reset and an initial value is set (S101). Next, based on one vibration sensor,
The difference time data measured by each vibration sensor is acquired (S102). The acquisition is continued until the data of all the vibration sensors are collected, and when the data is collected, the difference distance is calculated (S1).
04). If the data is not available (S103), the process returns to the initial value setting (S101). When the difference distance is obtained, the coordinates are calculated (S105), and for determining the certainty,
The distance from the coordinates to each sensor is calculated back (S10
6).

On the other hand, after the initial value setting (S101), in parallel with the coordinate calculation, an optical signal from the light emitting element 22 of the vibration input pen 21 is detected (S109), and as described above based on the detected optical signal. Then, time measurement is started with the generated start timing signal (S110), and the obtained phase delay time signal is obtained (S111). It is determined whether or not the delay time data of each vibration sensor is complete (S112), and if they are, distance calculation is performed (S113). If not, the process returns to the initial value setting (S101).

When the distance calculation is completed, the difference between the distance (S106) calculated backward from the coordinates and the distance (S113) obtained from the delay time data is compared with a predetermined threshold value (S1).
07). If the distance difference is larger than the threshold value, a process of not outputting coordinates is performed (S108). If the distance difference is smaller than the threshold value, the coordinates (S105) obtained from the difference distance are output as correct (S114).

In the second embodiment, as in the first embodiment,
Since the process of calculating the coordinates using the start timing signal based on the optical signal is not performed, there is an advantage that the accuracy of the start timing generation may be lower than in the first embodiment. In other words, a low-cost, low-speed light-emitting element can be used.

[0092]

As described above, according to the present invention,
A vibration transmission plate for transmitting elastic wave vibration, vibration input means for inputting elastic wave vibration to the vibration transmission plate, vibration detection means for detecting elastic wave vibration provided on an outer edge of the vibration transmission plate, and vibration input means. And a coordinate calculating means for calculating a coordinate position on the vibration transmitting plate of the vibration input means according to a time when the elastic wave vibration reaches the vibration detecting means, so that the configuration is simple, inexpensive and highly accurate. An electronic blackboard device that realizes pen input can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall configuration of an electronic blackboard device according to the present invention.

FIG. 2 is a schematic configuration diagram illustrating an example of a vibration input pen of the electronic blackboard device according to the present invention.

FIG. 3 is a schematic configuration diagram illustrating an example of an eraser of the electronic blackboard device according to the present invention.

FIG. 4 is a block diagram illustrating an example of a light detection circuit and a signal processing circuit of the electronic blackboard device according to the present invention.

FIG. 5 is a timing chart for explaining generation of a start timing signal in the signal processing circuit.

FIG. 6 is a block diagram showing an example of an arithmetic and control circuit of the electronic whiteboard device according to the present invention.

FIG. 7 is a block diagram illustrating an example of a signal waveform detection circuit of the electronic blackboard device according to the present invention.

FIG. 8 is a timing chart for explaining processing contents in the signal waveform detection circuit.

FIG. 9 is a diagram for explaining a coordinate calculation method in the electronic blackboard device according to the present invention.

FIG. 10 is a diagram illustrating an example of a method of dividing a region of a coordinate input surface for calculating coordinates.

11 is a diagram illustrating an example of a method of defining a difference between each region in FIG. 10 and a reference vibration sensor.

FIG. 12 is a flowchart illustrating a processing procedure from acquisition of difference time data to output of coordinates.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Operation control circuit 2 Light detection circuit 3 Signal processing circuit 4 Signal waveform detection circuit 5 Effective input area 6a-6d Vibration sensor 7 Vibration-proof material 8 Vibration transmission board 9,11,21 Vibration input pen 10,12,22 Light emitting element 13 Eraser 23 Power supply circuit 24 Light emitting element drive circuit 25 Vibrator drive circuit 26 Vibrator 27 Nib horn 28 Ink tank 281, 282 Electrode 29 Nib 291 Synthetic resin 31 Microcomputer 32a-32d Counter 33 Judgment circuit 34 Detection signal input circuit 35 I / O port 401 Preamplifier circuit 402 High-pass filter 403 Envelope detection circuit 404 Envelope inflection point detection circuit 405 Tg comparator 406 Gate signal generation circuit 407 Monostable multivibrator 408 Bandpass filter 409 Slice circuit 410 Tp comparator 601 Light receiving element 602 Amplifying circuit 603 Band pass filter 604 Low pass filter 605 First comparator 606 Gate signal generation circuit 607 Slice circuit 608 Second comparator 609 Start timing signal generation circuit

Continued on front page F-term (reference) 2C071 CA02 CD04 CD07 DA03 DC10 5B068 AA04 AA15 AA24 AA36 BB23 BC03 BC08 BD02 BD11 BD17 BD25 BE15 CC17 5B087 AA02 AA04 AE02 BC03 CC47 DD03 DD05 DD17 DG02

Claims (18)

[Claims] 1. A vibration transmitting plate for transmitting elastic wave vibration, vibration input means for inputting the elastic wave vibration to the vibration transmitting plate, and detecting the elastic wave vibration provided at an outer edge of the vibration transmitting plate. A vibration detecting unit, and a coordinate calculating unit that calculates a coordinate position of the vibration input unit on the vibration transmission plate according to a time when the elastic wave vibration from the vibration input unit reaches the vibration detecting unit. An electronic blackboard device, characterized in that: 2. The vibration input means includes a light emitting element driving means for outputting the optical signal at the same time as inputting the elastic wave vibration to the vibration transmission plate, and the coordinate calculating means includes: A light detecting unit that receives the signal; and a signal processing unit that generates a start timing signal in accordance with the optical signal. The timing of the arrival time is started in response to the start timing signal generated by the signal processing unit. The electronic blackboard device according to claim 1, wherein: 3. The signal processing unit reproduces a pulse train included in the optical signal to generate a pulse signal;
The method according to claim 2, further comprising: means for generating an envelope signal from the pulse train, generating a gate signal based on the envelope signal, and generating the start timing signal from the pulse signal and the gate signal. Electronic blackboard device as described. 4. The coordinate calculating means has group signal detecting means for detecting a group signal of the elastic wave vibration detected by the vibration detecting means to generate a vibration arrival timing signal, 3. The electronic whiteboard device according to claim 2, wherein in response, the timing of the arrival time is terminated. 5. The coordinate calculation unit includes a phase signal detection unit that detects a phase signal of the elastic wave vibration detected by the vibration detection unit and generates a vibration arrival timing signal.
The electronic whiteboard device according to claim 2, wherein the timing of the arrival time is ended in response to the vibration arrival timing signal. 6. The coordinate calculating means selects at least two of the vibration input means from among a plurality of the vibration detecting means provided on an outer edge of the vibration transmitting plate to calculate the coordinate position. The electronic blackboard device according to any one of claims 1 to 5, wherein 7. The coordinate calculating unit according to claim 1, wherein the coordinate calculating unit selects three of the plurality of vibration detecting units that have a short arrival time from among the plurality of vibration detecting units to calculate the coordinate position. The electronic blackboard device according to any one of claims 1 to 5. 8. The coordinate calculating means selects a reference vibration detecting means from among the plurality of vibration detecting means, and calculates the timing of arrival of the vibration between the reference vibration detecting means and the other vibration detecting means. The electronic blackboard device according to claim 4, wherein the coordinate position is calculated according to a time difference between signals. 9. The electronic whiteboard apparatus according to claim 1, wherein said vibration input means includes means for drawing ink directly on said vibration transmission plate. 10. The vibration input means according to claim 1, wherein said vibration input means includes means for erasing contents drawn directly with ink on said vibration transmission plate.
Electronic blackboard device according to the section. 11. An elastic wave vibration input to a vibration transmission plate by vibration input means is detected by vibration detection means provided on an outer edge of said vibration transmission plate, and said elastic wave vibration from said vibration input means is detected by said vibration input means. A coordinate calculation method, wherein a coordinate position of the vibration input means on the vibration transmission plate is calculated according to a time required to reach the detection means. 12. A light detection step of inputting the elastic wave vibration to the vibration transmission plate and simultaneously detecting an optical signal output from the vibration input means, and a signal processing step of generating a start timing signal according to the optical signal. And timing of the arrival time is started in response to the start timing signal.
The coordinate calculation method described in. 13. The method according to claim 1, wherein the signal processing step comprises the steps of: generating a start signal from the pulse signal obtained by reproducing a pulse train included in the optical signal; and a gate signal generated from the pulse train based on the envelope signal. 13. The method according to claim 12, wherein
The coordinate calculation method described in. 14. A group signal detecting step of generating a vibration arrival timing signal by detecting a group signal of the elastic wave vibration detected by the vibration detecting means, and responsive to the vibration arrival timing signal, 13. The coordinate calculation method according to claim 12, wherein the counting of the time to perform is ended. 15. A phase signal detecting step of detecting a phase signal of the elastic wave vibration detected by the vibration detecting means to generate a vibration arrival timing signal, and in response to the vibration arrival timing signal, 13. The coordinate calculation method according to claim 12, wherein the counting of the time to perform is ended. 16. A coordinate according to claim 11, wherein at least two of said plurality of vibration detecting means are selected to calculate said coordinate position. Calculation method. 17. The coordinate position is calculated by selecting three of said plurality of vibration detecting means from among a plurality of said vibration detecting means, and calculating said coordinate position. The coordinate calculation method described in the section. 18. A vibration detecting means serving as a reference is selected from a plurality of vibration detecting means, and the vibration detecting means serving as a reference is selected according to a time difference between the vibration arrival timing signals of the other vibration detecting means and the reference vibration detecting means. 16. The coordinate calculation method according to claim 14, wherein the coordinate position is calculated.