JPH0519948A - Coordinate input device - Google Patents

Abstract

(57) [Abstract] [Purpose] To eliminate the reflected wave from the end of the vibration transmission plate 8,
The vibration by the vibrating pen 3 can be accurately detected. [Structure] When the vibration transmitting plate 8 is pressed by the vibrating pen 3, the vibration of the pen 3 is detected by the sensor 6 and the coordinates pressed by the pen are determined. At that time, a reflected wave is generated in the peripheral portion of the vibration transmitter 8 and adversely affects the detection of vibration by the sensor. Therefore, the main body outer frame 20 around the transmission plate 8 is made of a material having the same acoustic impedance as that of the transmission plate 8, and is closely attached to the transmission body 8. As a result, the vibration of the transmission plate 8 is efficiently transmitted to the outer frame 2
It can propagate to 0 and suppress the reflected wave.

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 or the like for detecting the coordinates of a designated point from the vibration transmission time on a vibration transmission plate.

[0002]

2. Description of the Related Art Conventionally, a vibration pen having a built-in piezoelectric element or the like is used to input vibration to the vibration transmission plate.
There is known a coordinate input device that detects an input vibration by a plurality of sensors provided on a vibration transmission plate and measures a vibration transmission time to detect coordinates of an input point.

In such a coordinate input device, the end of the vibration transmitting plate is provided with a vibration-proof material so that an error does not occur in the detection by the vibration sensor due to the reflected wave of the input signal at the end of the vibration transmitting plate. A supporting structure is used.

The conventional anti-vibration material was developed mainly for noise prevention and is roughly classified into air noise countermeasures and fixed noise countermeasures. Therefore, in order to use the conventional antivibration material for the above-mentioned applications, the one for solid noise is used. As a conventional damping material for countermeasures against solid noise, there is a damping sheet for thin plate or paint as shown in FIG. 9 (A).

In FIG. 9 (A), 8'denotes a vibration material to be damped, and 7 denotes a vibration damping sheet. The vibrating plate 8'is composed of a metal plate such as a thin steel plate or an aluminum plate, or a resin plate or a glass plate.

In such a structure, the vibrating diaphragm 8'is vibrated.
By attaching the vibration damping sheet 7 to the vibration damping sheet 7, the vibration damping of the vibration damping sheet 7 can be utilized to reduce the vibration of the diaphragm 8'and reduce the noise.

The material of the vibration damping sheet 7 on the market is
There are polyvinyl chloride, tactic polypropylene, polyethylene vinyl acetylate, styrene butadiene rubber, silicone rubber, and Celent paste, and these also include plasticizers, stabilizers, softeners, metal powders such as lead and iron, silica sand, asphalt. Etc. are added or mixed. As a molding shape of these materials, there is a sponge-like porous shape.

[0008]

However, it is considered that the conventional vibration damping sheet as described above is mounted on the entire vibrating plate to suppress the vibration of the entire plate.

Therefore, in order to suppress the reflected wave at the end portion of the vibration transmission plate as described above, a vibration damping sheet is attached around the vibration transmission plate 8 as shown in FIG. 9B. However, the reflected wave could not be reduced sufficiently.

FIG. 9 (B) is a diagram showing vibration propagation when a vibration damping sheet is attached to the periphery of the vibration transmitting plate, FIG. 9 (C).
FIG. 9A is a part of the cross-sectional view of FIG. 9B, showing a state of reflected waves. 8 is a vibration transmitting plate, 7 is the vibration damping sheet, 3
Is a vibrating pen which is a vibration source, A is a wave showing vibration propagating from an exciting point which is a contact point between the vibrating pen 3 and the vibration transmitting plate 8, B is a reflected wave at the vibration transmitting end face, and C is a wave. It is each showing typically the reflected wave in the damping sheet mounting interface.

The conventional damping sheet 7 has a large damping effect on the vibration (natural vibration, that is, resonance vibration is included) generated in the entire plate as described above, but as shown in FIG. 9B. In addition, since the vibration damping sheet 7 is vibrated in a region where the vibration damping sheet 7 is not mounted, and a sufficient vibration damping effect cannot be obtained against the vibration as a traveling wave propagating from the vibration damping sheet 7, the vibration damping sheet as shown in FIG. Although it is slightly attenuated at the mounting portion D, the reflected wave B at the end surface of the vibration transmission plate cannot be sufficiently suppressed. Yotsutte
By increasing the width of the vibration damping sheet 7, it is necessary to suppress the reflected wave from the end surface of the vibration transmission plate. For this reason, the peripheral portion of the outer shape of the vibration transmission plate is an invalid area in which coordinates cannot be input as an area for mounting the wide damping sheet 7.

Further, by mounting the conventional damping sheet 7, a reflected wave C is newly generated on the damping sheet mounting surface. In order to suppress the reflection from the mounting surface of the vibration damping sheet 7, it is necessary to select a material for the vibration damping sheet 7 that has a smaller acoustic impedance than the acoustic impedance of the vibration transmission plate. Further, if a material having a low acoustic impedance is used, the ability to suppress reflection at the end surface of the vibration transmission plate becomes weaker, so it is necessary to make the width of the vibration damping sheet 7 wider.

Therefore, by mounting the conventional damping sheet on the periphery of the vibration transmitting plate of the coordinate input device using the elastic wave, the two reflected waves are generated and the direct wave from the vibration source is detected. However, there is a drawback in that it causes noise and reduces the detection accuracy. Furthermore, in order to suppress the reflected waves from the end surface of the vibration transmission plate, it is necessary to widen the width of the damping sheet.
Therefore, the invalid area in which the coordinates cannot be input is increasing.

The present invention has been made in view of the above-mentioned conventional example, and an object of the present invention is to provide a coordinate input device capable of efficiently suppressing reflected waves which become noise without reducing the effective area of the coordinate input surface.

[0015]

In order to achieve the above object, the coordinate input device of the present invention has the following configuration.

A coordinate input device for specifying coordinates of a vibration source based on a vibration transmission time from the vibration source, the first vibration transmitting means and a second vibration transmitting means in close contact with the first vibration transmitting means. Equipped with.

[0017]

According to the above construction, the vibration propagating through the first vibration transmitting means propagates to the second vibration transmitting means, and the reflected wave at the end of the first vibration transmitting means is reduced.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the drawings.

FIG. 1A shows the structure of a coordinate input device adopting the present invention. The coordinate input device of FIG.
An information input / output device for characters, figures, images, etc. is configured together with the display 18 having a display system such as a dot matrix system.

In the figure, the reference numeral 8 indicates a vibration transmission plate made of acrylic or glass plate, and the vibration pen 3
The vibration transmitted from is transmitted to the three vibration sensors 6 provided on the periphery thereof.

In the coordinate detection using the vibrating pen in this embodiment, the vibration time of the vibration pen 3 is measured by measuring the transmission time of the ultrasonic vibration transmitted from the vibration pen 3 to the vibration sensor 6 via the vibration transmission plate 8. The coordinates on the transmission plate 8 are detected.

In order to prevent the vibration transmitted from the vibrating pen 3 from being reflected at the peripheral portion and returning to the central portion, the vibration transmitting plate 8 has a vibration transmitting plate end face as shown in FIG. 1 (B). It is adhered to the outer frame 20 of the main body through adhesion or grease.

The body outer frame 20 is made of a material having an acoustic impedance substantially equal to that of the vibration transmission plate 8. For example, if glass is used for the vibration transmitting plate 8, the main body outer frame 20 is made of aluminum, and if it is acrylic, a plastic material such as epoxy resin is used. Further, the outer frame 20 of the main body is shown in FIG.
As shown in, the size is slightly larger than the shape of the vibration transmitting plate 8 and the structure is bent downward.

The vibration transmission plate 8 is arranged on a display device 18 such as a CRT (or a liquid crystal display device) capable of displaying dots and is adapted to perform a dot display at a position traced by the vibration pen 3. That is, the detected vibration pen 3
The dot display is performed at the position on the display 18 corresponding to the coordinates of the, and the image composed of elements such as points and lines input by the vibrating pen 3 is the locus of the vibrating pen as if it were written on paper. Appears after.

Further, according to such a configuration, the display 18
Alternatively, an input method may be used in which a menu display is performed and the menu item is selected by the vibrating pen, or a prompt is displayed to bring the vibrating pen 3 into contact with a predetermined position.

The vibrating pen 3 for transmitting ultrasonic vibrations to the vibration transmitting plate 8 has a vibrator 4 internally formed of a piezoelectric element or the like.
The ultrasonic vibration generated by the vibrator 4 is transmitted to the vibration transmission plate 8 via the horn portion 5 having a sharp tip.

FIG. 2 shows the structure of the vibrating pen 3. The vibrator 4 built in the vibrating pen 3 is driven by the vibrator driving circuit 2. The drive signal of the vibrator 4 is supplied as a low-level pulse signal from the arithmetic and control circuit 1 of FIG. 1, amplified by a predetermined gain by the vibrator drive circuit 2 capable of low impedance driving, and then the vibrator. 4 is applied.

The electric drive signal is converted into mechanical ultrasonic vibration by the vibrator 4 and transmitted to the diaphragm 8 via the horn section 5.

The vibration frequency of the vibrator 4 is selected to a value capable of generating a plate wave on the vibration transmission plate 8 such as acrylic or glass. Further, when the vibrator is driven, a vibration mode in which the vibrator 4 mainly vibrates in the vertical direction of FIG. Further, by setting the vibration frequency of the vibrator 4 as the resonance frequency of the vibrator 4, it is possible to perform efficient vibration conversion.

The elastic wave transmitted to the vibration transmitting plate 8 as described above is a plate wave, and has the advantage that it is less susceptible to scratches and obstacles on the surface of the vibration transmitting plate 8 compared to surface waves. Have.

Referring again to FIG. 1A, the vibration transmission plate 8
The vibration sensor 6 provided at the end of is also composed of a mechanical-electrical conversion element such as a piezoelectric element. The output signals of the three vibration sensors 6 are input to the waveform detection circuit 6 and converted into detection signals that can be processed by the arithmetic control circuit 1 in the subsequent stage. The arithmetic control circuit 1 performs the measurement process of the vibration transmission time,
The coordinate position of the vibration pen 3 on the vibration transmission plate 8 is detected.

The detected coordinate information of the vibrating pen 3 is processed in the arithmetic control circuit 1 according to the output system of the display 18. That is, the arithmetic control circuit controls the output operation of the display 18 via the video signal processing device 10 based on the input coordinates.

FIG. 3 shows the structure of the arithmetic control circuit 1 of FIG. Here, the structure of the drive system of the vibration pen 3 and the vibration detection system by the vibration sensor 6 is mainly shown.

The microcomputer 11 has a built-in internal counter, ROM and RAM. The drive signal generation circuit 12 outputs a drive pulse of a predetermined frequency to the vibrator drive circuit 2 of FIG.
1 is started in synchronization with the circuit for coordinate calculation.

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

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

The timing signal input from the waveform detection circuit 9 is input to the input port 15 and stored in the 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 the coordinate calculation is performed based on this vibration transmission time value. At this time, the determination circuit 16 determines whether or not all the waveform detection timing information from the plurality of vibration sensors 6 has been input, and notifies the microcomputer 11 of it.

The output control processing of the display 18 is performed via the input / output port 17.

FIG. 4 illustrates a detected waveform input to the waveform detection circuit 9 of FIG. 1 and a vibration transmission time measuring process based on the detected waveform. In FIG. 4, reference numeral 41 indicates a drive signal pulse applied to the vibrating pen 3. The ultrasonic vibration transmitted to the vibration transmission plate 8 from the vibration pen 3 driven by such a waveform passes through the inside of the vibration transmission plate 8 and is detected by the vibration sensor 6.

After traveling through 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. Since the plate wave used in this embodiment is a dispersive wave, the relationship between the envelope 421 and the phase 422 of the detected waveform changes according to the vibration transmission distance.

Here, the advance velocity of the envelope is the group velocity V
g and the phase velocity is Vp. The distance between the vibration pen 3 and the vibration sensor 6 can be detected from the difference between the group velocity and the phase velocity.

First, focusing only on the envelope 421, its velocity is Vg, and when a point on a certain specific waveform, for example, a peak is detected as indicated by reference numeral 43 in FIG. 4, it is detected between the vibration pen 3 and the vibration sensor 6. The distance d of the vibration transmission time is tg, and d = Vg · tg (1) This formula relates to one of the vibration sensors 6, but the other two vibration sensors 6 and the vibration pen 3 are expressed by the same formula. Can indicate the distance.

Further, in order to determine the coordinate value with higher accuracy, processing based on the detection of the phase signal is performed. If a specific detection point of the phase waveform 422 in FIG. 4, for example, the time from the vibration application to the zero-cross point after the peak is passed 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 expressed as n = [Vg.tg-Vp.tp) /. Lambda.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 n is within ± 1/2 wavelength, n can be determined.

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

For measuring the two vibration transmission times tg and tp shown in FIG. 3, the waveform detection circuit 9 can be constructed, for example, as shown in FIG.

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

The amplified signal is an envelope detection circuit 5
2 and 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.
The envelope detection time detection signal Tg having a predetermined waveform is formed from the peak detection signal by the signal detection circuit 54 including a mono-multivibrator, and the arithmetic control circuit 1
Entered in.

The phase delay time detection signal Tp is formed by the detection circuit 58 from the timing of this Tg signal and the original signal delayed by the delay time adjustment circuit 57, and is input to the arithmetic control circuit 1.

That is, the Tg signal is converted into a pulse having a predetermined width by the monostable multivibrator 55. Also,
The comparator level supply circuit 56 forms a threshold value for detecting the signal tp according to the pulse timing. As a result, the comparator level supply circuit 56 forms the signal 44 having the level and timing as indicated by reference numeral 44 in FIG. 3, and inputs the signal 44 to the detection circuit 57.

That is, the monostable multivibrator 55
And the comparator level supply circuit 56 is for making the measurement of the phase delay time operate only for a fixed time after the envelope peak is detected.

This signal is input to the detection circuit 58 composed of a comparator or the like and compared with the detection waveform delayed as shown in FIG. 4, and as a result, a tp detection pulse such as reference numeral 45 is formed.

The circuit shown above is for one vibration sensor 6, and the same circuit is provided for each of the other sensors. If the lower figure of the sensor is generalized to h,
Envelope delay time Tg1 to h, phase delay time Tp1
Each of h detection signals from to h is input to the arithmetic control circuit 1.

In the arithmetic control circuit of FIG. 3, the above Tg1 to h
The Tp1 to h signals are input from the input port 15, each timing is taken out, and the count value of the counter 13 is taken into the latch circuit 14. As described above, since the counter 13 is started in synchronization with the driving of the vibrating pen, the latch circuit 14 receives the data indicating the delay time of each of the envelope and the phase.

When the three vibration sensors 6 are arranged at the corners of the vibration transmission plate 8 at the positions S1 to S3 as shown in FIG.
According to the processing described with reference to FIG. 4, the linear distances d1 to d1 from the position P of the vibration pen 3 to the position of each vibration sensor 6
d3 can be obtained. Further, the arithmetic control circuit 1 can obtain the coordinates (x, y) of the position P of the vibrating pen 3 based on the linear distances d1 to d3 by the following formula from the Pythagorean theorem. However, S1, S2, and S3 are assumed to have coordinates (0,0), (X, 0), and (0, Y), respectively.

X = X / 2 + (d1 + d2) · (d1-d2) / 2X (4) y = Y / 2 + (d1 + d3) · (d1-d3) / 2Y (5) where x and y are respectively This is the distance along the X-axis and Y-axis between the vibration sensor 6 at the positions S2 and S3 and the sensor at the origin (position S1).

As described above, the position coordinates of the vibrating pen 3 can be detected in real time. Here, in order to simplify the description, the sensor arrangement corresponding to the Cartesian coordinate system is illustrated as shown in FIG. 6, but even when the sensor arrangement as shown in FIG. Can be determined.

Here, the effect of using the configuration as shown in FIGS. 1A and 1B will be described. Body outer frame 2
0 is made of a material having an acoustic impedance substantially equal to the acoustic impedance of the vibration transmission plate 8. Assuming that the acoustic impedance of the conduction transfer plate 8 is C1 and the acoustic impedance of the main body outer frame 20 is C2, the reflectance R at the interface between the conduction transmission plate 8 and the main body outer frame 20 is: It is well known that it becomes like a formula.

R = (C2-C1) / (C2 + C1) (6) When C1 = C2, R = 0, and the reflection at the boundary surface of the materials having the same acoustic impedance becomes zero. This is because even if the vibration is obliquely input to the boundary, C1 = C2 similarly.
It is also well known that R = 0.

Considering the actual acoustic impedance value, for example, the vibration transmission plate 8 is made of glass (C1 = 1.70 ×).
10 ⁷ kg / m ² ) and aluminum (C2 = 1.6
The reflectance when 9 × 10 ⁷ kg / m ² ) is selected is R = 0.003 from the equation (6), and only 0.3% of the direct wave is reflected.

Focusing on the vibration transmitted from the vibration transmission plate 8 to the main body outer frame 20, even if the vibration propagates in the main body outer frame 20, is reflected by the end surface of the main body outer frame 20, and propagates to the vibration transmission plate 8 again. , There is a large time delay with respect to the direct wave, and it does not become noise when detecting.

As described above, as the main body outer frame 20 to which the vibration transmitting plate 8 is attached, a material having substantially the same acoustic impedance as that of the vibration transmitting plate is used, and the vibration transmitting plate 8 is adhered to the outer frame at its periphery or grease is used. It is possible to reduce the reflected wave from the end surface of the vibration transmission plate by closely fixing it through the above, and further to reduce the noise at the time of vibration detection without forming an invalid area on the vibration transmission plate 8 to detect the coordinate. There is an excellent effect that the accuracy can be improved.

[0063]

[Other Embodiments] FIG. 7 shows a structure in which the outer frame 20 of the main body is one piece.
Another embodiment will be described. In FIG. 7, the vibration transmitted from the vibration transmission plate 8 to the main body outer frame 20 reaches the vibration transmission plate 8 on the opposite side across the main body outer frame 20. Therefore, the time delay with respect to the direct wave can be made larger than that of the structure of FIG.

Further, the overall shape of the coordinate input device is small,
Therefore, when the shape of the main body outer frame 20 cannot be made large, the time delay becomes small, and there is a problem of vibration returning from the main body outer frame 20 to the vibration transmission plate 8 again. FIG. 8 shows another embodiment effective in such a case.

As shown in FIG. 8, the damping sheet 7 is attached to the outer frame 20 of the main body.
By mounting the, the transmitted vibration propagating through the main body outer frame 20 can be suppressed during the propagation. According to this configuration, it is possible to increase the mounting area of the vibration damping sheet 7 and suppress the vibration of the outer frame 20 of the main body, but since the mounting area is not inside the vibration transmission plate, an ineffective area, which has been a problem in the past, occurs. Absent.

If the vibration transmission plate 8 and the main body outer frame 20 are integrally molded, the reflection of vibration at the joint can be suppressed almost completely.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0068]

As described above, the coordinate input device according to the present invention can efficiently suppress the reflected wave that becomes noise without reducing the effective area of the coordinate input surface.

As is apparent from the above, according to the present invention, the vibration input from the vibrating pen is detected by a plurality of vibration sensors provided on the vibration transmitting plate to determine the coordinates of the vibrating pen on the vibration transmitting plate. In the coordinate input device to detect,

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of an example.

2 is an explanatory view showing the structure of the vibrating pen of FIG. 1. FIG.

3 is a block diagram showing the structure of the arithmetic and control unit of FIG.

FIG. 4 is a waveform diagram showing detection waveforms for explaining the distance measurement between the vibration pen and the vibration sensor.

5 is a block diagram showing a configuration of the waveform detection circuit of FIG.

FIG. 6 is an explanatory diagram of a process of determining coordinates of a vibration source.

[Figure 7]

FIG. 8 is an explanatory diagram showing the configuration of another embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a conventional mounting structure for a vibration isolator.

[Explanation of symbols]

1 ... Operation control circuit 3 ... Vibration pen 4 ... Transducer 6 ... Vibration sensor 7 ... Anti-vibration material 8 ... Vibration transmission plate 9 ... Signal waveform detection circuit 10 ... Display driving circuit 18 ... Display 20 ... Main frame

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Jun Tanaka             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Kiyoshi Kaneko             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation

Claims (4)

[Claims] 1. A coordinate input device for specifying coordinates of a vibration source according to a vibration transmission time from the vibration source, comprising a first vibration transmission means and a second vibration transmission in close contact with the first vibration transmission means. A coordinate input device comprising: 2. The coordinate input device according to claim 1, wherein the second vibration transmitting means has an acoustic impedance of the same value as or a value close to that of the first vibration transmitting means. 3. The coordinate input device according to claim 1, wherein the second vibration transmission means is formed in a box shape. 4. The coordinate input device according to claim 3, wherein a vibration isolator is bonded to the second vibration transmission means.