JPH02129713A - Coordinate input device - Google Patents

Abstract

PURPOSE:To constitute the title device so that a homogeneous vibration detecting signal can be obtained with regard to all vibration sensors and a coordinate can be detected with high accuracy by setting a mechanical resonance frequency of the vibration sensor higher than vibration frequency detected by the vibration sensor. CONSTITUTION:An input tablet consisting of a vibration transfer plate 8 is allowed to execute a coordinate input by a vibrating pen 3, and in accordance with inputted coordinate information, an input image is displayed on an indicator 11' consisting of a CRT which is superposed and placed on the input tablet. In such a case, a resonance frequency of a vibration sensor 6 is set higher than a vibration frequency inputted to the vibration transfer plate 8. In such a way, as for a vibration frequency band used actually for a coordinate operation, a vibration detection characteristic of the vibration sensor 6 can be broadened, and by eliminating an influence of the resonance frequency of the vibration sensor 6 by a simple and inexpensive means, an exact coordinate operation can be executed.

Description

Detailed Description of the Invention [Industrial Application tf1 The present invention detects mechanical vibrations input from a coordinate input device, particularly a vibrating pen, with a vibration sensor installed at a predetermined position on a vibration transmission plate, and generates vibrations. The present invention relates to a coordinate input device that detects the position of vibration input to the vibration transmission plate by the vibrating pen from the vibration transmission time on the transmission plate.

[Prior Art] Coordinate input devices using various input pens, tablets, etc. have been known as devices for inputting handwritten characters, figures, etc. to a processing device such as a computer. In this type of system, input image information consisting of characters, graphics, etc. is output to a display device such as a CRT display or a recording device such as a printer.

In this type of device, ultrasonic vibrations transmitted from a vibration input pen to a tablet are input to a vibration transmission plate, detected from the input point by a vibration sensor installed at a predetermined part of the vibration transmission plate, and transmitted to each sensor. In the 0wA sound wave system, which is known to have a configuration in which the coordinates of an input point are identified based on the transmission time, the structure of the input tablet is relatively thin, which makes the device configuration simple and inexpensive, and the tablet is made of a transparent material. It has the advantage of being able to be used over the display, display, and original.

[Problems to be Solved by the Invention] In the vibration sensor of the above-mentioned photographic coordinate input device, it is desirable that the output gains of the plurality of vibration sensors provided on the vibration transmission plate be approximately constant. It is.

For this reason, in the past, it has been common to take measures to prevent variations in the resonance frequency of the vibration sensor regarding mechanical vibrations.

However, the relationship between the resonant frequency of the vibration sensor and other conditions, such as the drive frequency of the vibrator of the vibrating pen, is not strictly considered, and the drive frequency of the vibrator and the resonant frequency of the vibration sensor are almost matched. Only a few settings were made.

However, as mentioned above, it is necessary to make the driving frequency of the vibrator almost equal to the resonance frequency of the vibration sensor, that is, to make the frequency band of the vibration detected by the vibration sensor almost equal to the driving frequency band of the vibrator, or to reduce the resonance of the vibration sensor. If the frequency is set lower than the driving frequency of the vibrator, the detected waveform of the vibration sensor will include a resonance component of the vibration sensor that is lower than the driving frequency of the vibrator, and this effect will distort the waveform. A problem arises in that vibration detection timing cannot be performed accurately and coordinate detection accuracy decreases.

For example, if the resonance frequencies of a plurality of vibration sensors vary, the detection waveforms of the plurality of vibration sensors will not be aligned, and if the same waveform processing system is used for each vibration sensor, the detection timing will be inconsistent.

It requires sophisticated production management and adjustment processes to completely align the variations in resonance frequency of all vibration sensors.
There is a problem of high cost.

Another possibility is to lower the Q of the resonance band of the vibration sensor to avoid the effects of variations in the resonance frequency of the vibration sensor, but this also requires measures such as attaching a damping material to the vibration sensor, which also raises the problem of high costs. there were.

In view of the above problems, an object of the present invention is to reliably eliminate the influence of the resonant frequency of a vibration sensor by simple and inexpensive means, and to perform accurate coordinate calculations.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, mechanical vibrations input from a vibrating pen are detected by a vibration sensor provided at a predetermined position on a vibration transmission plate. In a coordinate input device that detects the position of vibration input to the vibration transmission plate by the vibration pen from the vibration transmission time on the vibration transmission plate, the mechanical resonance frequency of the vibration sensor is higher than the vibration frequency detected by the vibration sensor. The configured configuration was adopted.

[Function] According to the above configuration, the resonance frequency of the vibration sensor is set higher than the vibration frequency input to the vibration transmission plate, so the vibration frequency band actually used for coordinate calculation is determined by the vibration sensor. Vibration detection characteristics can be made broader.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

′! Figure J1 shows the structure of an information input/output device employing the present invention. The information input/output device shown in FIG. 1 inputs coordinates to an input tablet consisting of a vibration transmitting plate 8 using a vibrating pen 3, and a display 11° consisting of a CRT placed over the input tablet according to the input coordinate information. The input image is displayed on the screen.

In the figure, the reference numeral 8 is a vibration transmission plate made of acrylic, glass, etc., which transmits vibrations transmitted from the vibrating pen 3 to the three vibration sensors 6.

The vibration transmitting plate 8 includes a vibration isolating material 7 made of silicone rubber or the like in its peripheral portion in order to prevent vibrations transmitted from the vibrating pen 3 from being reflected at the peripheral portion and returning toward the center.
Supported by

In order to reduce the influence of reflected waves from the boundary surface of the vibration isolating material 7,
It is attached on the boundary surface of the attached vibration isolating material 7 or very close to it. The mounting method may be adhesive or pressure welding.

The vibration transmission plate 8 is arranged on a display device 11, such as a CRT (or liquid crystal display, etc.) capable of displaying dots, and displays dots at the position traced by the vibrating ben 3. That is, a dot is displayed at a position on the display 11' corresponding to the detected coordinates of the vibrating ben 3, and an image composed of elements such as points and lines input by the vibrating ben 3 is displayed as if it were written on paper. Appears after the trajectory of the vibrating ben as if it were done.

In addition, according to such a configuration, a menu is displayed on the display 11', and the menu item is selected using the vibrating bezel, or a prompt is displayed and the vibrating ben 3 is brought into contact with a predetermined position. You can also use

The vibration ben 3 transmits ultrasonic vibration to the vibration transmission plate 8.
It has a vibrator 4 made of a piezoelectric element or the like inside, and transmits ultrasonic vibrations generated by the vibrator 4 to a vibration transmission plate 8 via a horn portion 5 having a sharp tip.

FIG. 2(A) shows the structure of the vibrating vent 3. A vibrator 4 built into the vibrator 3 is driven by a vibrator drive circuit 2. The drive signal for the vibrator 4 is supplied as a low-level pulse signal from the arithmetic and control circuit 1 shown in FIG.
After being amplified by a predetermined gain by a vibrator drive circuit 2 capable of low impedance driving, the electric drive signal is applied to the vibrator 4.The vibration frequency of the mechanical vibrator 4 is set by the acrylic , vibration transmission plate 8 such as glass
is selected to a value that allows plate waves to be generated. Further, when driving the vibrator, a photographing mode is selected in which the vibrator 4 mainly vibrates in the vertical direction in FIG. 2 with respect to the vibration transmission plate 8. Further, by setting the vibration frequency of the vibrator 4 to the resonance frequency of the vibrator 4, efficient vibration conversion is possible.

The elastic waves transmitted to the vibration transmission plate 8 as described above are plate waves, which have the advantage that they are less susceptible to the effects of scratches, obstacles, etc. on the surface of the vibration transmission plate 8 compared to surface waves.

Again, in FIG. 1, the vibration sensor 6 provided at the corner of the vibration transmission plate 8 is also constituted by a mechanical to electrical conversion element such as a piezoelectric element.

In this embodiment, the resonance frequency of the vibration sensor 6 is set as follows.

For example, when the driving frequency A of the vibrator is 400 KHz, the resonance frequency B of the vibration sensor 6 is set to a higher value of 500 KHz, as shown in FIG. 2(B).

As is clear from FIG. 2(B), the mechanical frequency characteristics of the vibration sensor 6 are approximately equal in the vibration frequency band centered around 400 KHz transmitted on the vibration transmission plate 8.

Therefore, if the resonance frequency of the vibration sensor 6 is set sufficiently higher than the frequency band actually used,
Even if the resonant frequency B of the piezoelectric element constituting the vibration sensor 6 varies by about ±50 KHz, substantially flat characteristics can be realized in the band actually transmitted on the vibration transmission plate 8.

Further, even if the resonant frequency of the vibration sensor 6 changes due to other conditions such as temperature, it similarly does not affect the detection of the band actually used.

Furthermore, even if control is performed to change the drive frequency of the vibrator 4 for the purpose of correcting the origin position, the vibration sensor 6
The output signal is not affected by the resonance frequency of the vibration sensor 6.

As in the conventional case, if the resonance frequency B of the vibration sensor 6 and the band of the actually transmitted vibration frequency A are almost equal, or if the resonance frequency B of the vibration sensor 6 is lower,
As mentioned above, the detection waveform of the vibration sensor includes a resonance component of the vibration sensor that is lower than the drive frequency of the vibrator, and this effect distorts the waveform, making it impossible to perform vibration detection timing accurately and reducing coordinate detection accuracy. However, if the resonance frequency of the vibration sensor 6 is set higher than the actual usage band as described above, the waveform processing described below can be performed accurately and the accuracy of coordinate calculation can be greatly improved.

Note that the settings of the actually transmitted vibration frequency A and the resonance frequency B of the vibration sensor 6 (400 and 500 KHz) are just examples, and it goes without saying that the frequencies A and B are not limited to these frequency values.

Next, the configuration and operation of the vibration waveform detection system and the coordinate detection system will be explained.

The output signals of each of the three vibration sensors 6 shown in FIG. 1 are input to the waveform detection circuit 9, and are converted into detection timing signals that can be processed by the arithmetic control circuit 1 through waveform detection processing, which will be described later. This detection timing signal is input to the arithmetic control circuit 1.

The arithmetic control circuit 1 detects the vibration transmission time to each sensor based on the detection timing input from the waveform detection circuit, and further detects the coordinate input position of the vibration ben 3 on the vibration transmission plate 8 from this vibration transmission time.

The detected coordinate information of the vibrating vent 3 is processed in the arithmetic control circuit 1 according to the output method by the display 11'.

That is, the arithmetic control circuit controls the output operation of the display 11° via the video signal processing device 10 based on the input coordinate information.

FIG. 3 shows the structure of the arithmetic control circuit 1 shown in FIG.

Here, the structure of the drive system of the vibrating ben 3 and the vibration detection system using the vibration sensor 6 are mainly shown.

The microcomputer 11 includes an internal counter, ROM, and RAM. The drive signal generation circuit 12
It outputs a drive pulse of a predetermined frequency to the vibrator drive circuit 2 shown in the figure, and is activated by the microcomputer 11 in synchronization with the coordinate calculation circuit.

The count value of the counter 13 is latched into the latch circuit 14 by the microcomputer 11.

On the other hand, the waveform detection circuit 9 outputs timing information of a detection signal for measuring vibration transmission time from the output of the imaging sensor 6 as described later. These timing information are input to input ports 15, respectively.

A timing signal input from the waveform detection circuit 9 is input to the input port 15 and stored in a storage area corresponding to each vibration sensor 6 in the latch circuit 14, and the result is transmitted to the microcomputer 11.

That is, the vibration transmission time is expressed as a latch value of the output data of the counter 13, and coordinate calculation is performed using this vibration transmission time value. At this time, the determination circuit 16 determines whether all waveform detection timing information from the plurality of vibration sensors 6 has been input, and
Notify 1.

Output control processing for the display device 11° is performed via the human output boat 17.

FIG. 4 explains the detected waveform input to the waveform detection circuit 9 of FIG. 1 and the vibration transmission time measurement process based on the detected waveform. In FIG. 4, the reference numeral 41 indicates a drive signal pulse applied to the vibrating ben 3. As shown in FIG. Ultrasonic vibrations transmitted from the vibration ben 3 driven by such a waveform to the vibration transmission plate 8 pass through the vibration transmission plate 8 and are detected by the vibration sensor 6.

After traveling within the vibration transmission plate 8 for a time tg corresponding to the distance to the vibration sensor 6, the vibration reaches the vibration sensor 6. Reference numeral 42 in FIG. 4 indicates a signal waveform detected by the vibration sensor 6. The plate wave used in this embodiment is a dispersive wave, so the envelope 42 of the detected waveform
The relationship between 1 and phase 422 changes depending on the vibration transmission distance.

Here, the advancing speed of the envelope is assumed to be group velocity vg, and the phase velocity is assumed to be Vp. The distance between the vibration sensor 3 and the vibration sensor 6 can be detected from the difference in group velocity and phase velocity.

First, if we focus only on the envelope 421, its velocity is Vg, and when a point on a certain waveform, for example a peak, is detected as indicated by reference numeral 43 in FIG. lid is d=Vg-tg where the vibration transmission time is tg
(1) Although this equation relates to one of the vibration sensors 6, the distances between the other two vibration sensors 6 and the vibration ben 3 can be expressed using the same equation.

Furthermore, in order to determine coordinate values with higher precision, processing based on phase signal detection is performed. Phase waveform 4 in Figure 4
22 specific detection points, for example, if the time from the imaging application to the zero cross point after passing the peak is tp, the distance between the vibration sensor and the vibration pen is d=n ・λp+Vp-tp...
(2) becomes. Here, λp is the wavelength of the elastic wave, and n is an integer.

From the above equations (1) and (2), the above integer n is n =
[(Vg ・tg −Vp −tp)
/ λ p + 1/N ]... (3
). Here, N is a real number other than 0, and an appropriate value is used. For example, if N=2 and the fluctuation of the group delay time tg is within ±1/2 wavelength, n can be determined.

By substituting n determined as above into equation (2), the distance between the vibrating pen 3 and the vibration sensor 6 can be accurately measured.

In order to measure the two vibration transmission times tg and tp shown in FIG. 3, the waveform detection circuit 9 can be configured as shown in FIG. 5, for example.

In FIG. 5, the output signal of the vibration sensor 6 is amplified to a predetermined level by the amplification circuit 51 described above.

The amplified signal is input to the envelope detection circuit 52, and only the envelope of the detection signal is extracted. The timing of the peak of the extracted envelope is detected by the envelope peak detection circuit 53. From the peak detection signal, an envelope delay time detection signal Tg having a predetermined waveform is formed by a signal detection circuit 54 composed of a mono-multivibrator or the like, and is input to the arithmetic control circuit 1.

Further, a phase delay time detection signal "rp is formed by the detection circuit 58 from this Tg flaw signal timing and the original signal delayed by the delay time adjustment circuit 57, and is inputted to the arithmetic control circuit 1.

That is, the Tg flaw signal is converted into a pulse of a predetermined width by the monostable multivibrator 55. Further, the comparator level supply circuit 56 outputs t according to this pulse timing.
A threshold value for detecting the p-number is formed. As a result, the comparator level supply circuit 56 is connected to the reference numeral 44 in FIG.
A signal 44 having a level and timing as follows is generated and input to the detection circuit 58.

That is, the monostable multivibrator 55 and the comparator level supply circuit 56 are used to ensure that the phase delay time measurement is activated only for a certain period of time after the envelope peak is detected.

This signal is sent to the detection circuit 5 which is composed of a comparator etc.
8 and is compared with the delayed detection waveform as shown in FIG.

The circuit shown above is for one vibration sensor 6, and the same circuit is provided for each of the other sensors.

If the number of sensors is generalized to h, then h detection signals of envelope delay times Tgl to h and phase delay times Tpl to h are input to the arithmetic and control circuit 1, respectively.

In the arithmetic control circuit of FIG. 3, the above Tgl~h, Tp1~
The h signal is input from the input port 15, and the count value of the counter 13 is taken into the latch circuit 14 using each timing as a trigger. As described above, since the counter 13 is started in synchronization with the driving of the vibrating pen, the latch circuit 14 receives data indicating the respective delay times of the envelope and the phase.

When three vibration sensors 6 are arranged at the positions S1 to S3 at the corners of the vibration transmission plate 8 as shown in FIG. The straight-line distances d1 to d3 to the position of the vibration sensor 6 can be determined.

Furthermore, the arithmetic and control circuit 1 can determine the coordinates (x, y) of the position P of the vibrating pen 3 based on the straight-line distances d1 to d3 as shown in the following equation using the 3-square theorem.

x = X/2 * (di + d2)
(di −62) / 2X −(4)y−
Y/2 + (di + d3) (di
-d3) / 2Y... (5) Here, X, Y
is the vibration sensor 6 at positions S, 2, and S3 and the origin (position St
) is the distance along the X and Y axes of the sensor.

As described above, the position coordinates of the vibrating pen 3 can be detected in real time.

[Effects of the Invention] As is clear from the above, according to the present invention, mechanical vibration input from a vibrating pen is detected by a vibration sensor provided at a predetermined position on the vibration transmission plate, and the mechanical vibration is transmitted on the vibration transmission plate. In the coordinate input device that detects the position of vibration input to the vibration transmission plate by the vibration pen from the vibration transmission time, a configuration is adopted in which the mechanical resonance frequency of the vibration sensor is set higher than the vibration frequency detected by the vibration sensor. Therefore, the resonance frequency of the vibration sensor is set higher than the vibration frequency input to the vibration transmission plate, so the resonance characteristics of multiple vibration sensors may vary with respect to the vibration frequency band actually used for coordinate calculation. Even if the vibration detection characteristics change due to environmental conditions, etc., the vibration detection characteristics of the vibration sensor can be made broad, and homogeneous vibration detection signals can be obtained for all vibration sensors, allowing highly accurate coordinate detection. I can do it. Further, there is an excellent advantage that there is no need to perform damping to make the resonance characteristics of the vibration sensor uniform or to perform sophisticated quality control, and the structure of the device can be made simple and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the configuration of an information input/output device employing the present invention, FIG. 2 (A) is an explanatory diagram showing the structure of the vibrating pen in FIG. Figure 1 is a diagram showing the characteristics of the vibration sensor, Figure 3 is a block diagram showing the structure of the arithmetic control circuit in Figure 1, and Figure 4 is a detection diagram explaining distance measurement between the vibration pen and the vibration sensor. FIG. 5 is a block diagram showing the configuration of the waveform detection circuit of FIG. 1, and FIG. 6 is an explanatory diagram showing the arrangement of vibration sensors. 1... Arithmetic control circuit 3... Lifting vent 4... Vibrator 6... Vibration sensor 8... Vibration transmission plate 11... Micro'computer 13... Counter 14... Latch Circuit 15.17...Input boat 1 turn n to S+T-J and 1st special E to H"Customer 1a
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Claims (1)

[Scope of Claims] 1) Mechanical vibration input from a vibrating pen is detected by a vibration sensor provided at a predetermined position on a vibration transmission plate, and the vibration caused by the vibration pen is detected based on the vibration transmission time on the vibration transmission plate. A coordinate input device for detecting a position of vibration input to a transmission plate, characterized in that a mechanical resonance frequency of the vibration sensor is set higher than a vibration frequency detected by the vibration sensor. 2) The coordinate input device according to claim 1, wherein the mechanical resonance frequency of the vibration sensor is set higher than the vibration frequency that the vibration pen inputs to the vibration transmission plate.