JPH0758453B2 - Coordinate input device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a coordinate input device, and in particular, to a coordinate of a vibration input point by detecting a vibration input from a vibrating pen by a vibration sensor provided on a vibration transmission plate. The present invention relates to a coordinate input device for detecting.

[Prior Art] Conventionally, vibration input is performed by a vibrating pen having a piezoelectric element or the like built in a vibration transmission plate, input vibrations are detected by a plurality of sensors provided on the vibration transmission plate, and vibration transmission time is measured. A coordinate input device that detects the coordinates of an input point is known.

In such a coordinate input device, the end portion of the vibration transmitting plate is supported by a vibration isolator so that the input vibration is reflected at the end portion of the vibration transmitting plate and the reflected wave does not cause an error in the detection by the vibration sensor. The structure is used.

Conventional anti-vibration materials are mainly developed for noise prevention, and are roughly classified into those for air noise and those for solid noise. Therefore, in order to use the conventional vibration-damping material for the above-mentioned uses, a material for solid-state noise is used. As a conventional damping material for solid noise, there is a damping sheet for thin plate as shown in FIG. 11 (A), or paint.

In FIG. 11 (A), 8'is the diaphragm to be damped,
7 is a damping sheet. The vibrating plate 8'is made of a thin steel plate, a metal plate such as an aluminum plate, or a resin plate or a glass plate.

In such a configuration, the vibration damping sheet 7 is attached to the vibrating diaphragm 8 ', and the vibration damping of the vibration damping sheet 7 is utilized to reduce the vibration of the diaphragm 8'and reduce the noise. You can

Commercially available materials for the vibration damping sheet 7 include polyvinyl chloride resin, atactic polypropylene, polyethylene vinyl acetylate, styrene butadiene rubber, silicone rubber, cement paste, etc., and further plasticizer, stabilizer, softening agent Agents, 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.

[Problems to be Solved by the Invention] However, it is considered that the conventional vibration damping sheet as described above is mainly mounted on the entire vibrating plate to suppress the vibration of the entire plate.

Therefore, as described above, in order to suppress the reflected wave at the end of the vibration transmission plate, it is sufficient to use the vibration damping sheet mounted around the vibration transmission plate 8 as shown in FIG. 11 (B). The reflected waves could not be reduced.

FIG. 11 (B) is a diagram showing vibration propagation when the vibration damping sheet is attached to the periphery of the vibration transmission plate, and FIG. 11 (C) is a diagram showing the vibration propagation.
It is a part of sectional drawing of FIG. 11 (B), and is a figure which shows a mode of a reflected wave. Reference numeral 8 is a vibration transmission plate, 7 is the vibration damping sheet, 3 is a vibration pen for reducing vibration, and A is vibration propagated from a vibration point which is a contact point between the vibration pen 3 and the vibration transmission plate 8. A wave, B is a reflected wave at the vibration transmitting end surface, and C is a reflected wave at the damping sheet mounting boundary surface.

As described above, the conventional damping sheet 7 has a large damping effect on the vibrations (including natural vibrations, that is, resonance vibrations) generated on the entire plate, but as shown in FIG. The vibration damping sheet 7 is vibrated in a region where it 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. Therefore, 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.

Furthermore, by mounting the conventional damping sheet 7, a reflected wave C is newly generated at the damping sheet mounting interface. Therefore, if the conventional vibration damping sheet is attached to the peripheral portion of the vibration transmission plate of the coordinate input device using elastic waves, the above two reflected waves are generated and noise is generated when the direct wave from the vibration source is detected. Therefore, there is a drawback that the detection accuracy is lowered.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, the vibration input from the vibration pen is detected by the vibration sensor provided on the vibration transmission plate, and the vibration input point is detected. In the coordinate input device for detecting the coordinates of the vibration transmitting plate, a vibration isolator having a pattern shape in which the areas of the mounted portion and the non-mounted portion of the vibration transmitting plate change continuously or stepwise in the direction from the central portion to the peripheral portion. The material is provided on the periphery of the vibration transmitting plate, and the acoustic impedance is gradually changed in the direction from the central portion to the peripheral portion of the vibration transmitting plate.

[Operation] According to the above configuration, the acoustic impedance of the peripheral portion of the vibration transmitting plate can be configured to gradually change in the direction from the central portion to the peripheral portion, and the reflected wave generated in the peripheral portion of the vibration transmitting plate can be generated. It is possible to reduce the noise, reduce noise during vibration detection, and improve coordinate detection accuracy.

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

FIG. 1A shows the structure of a coordinate input device adopting the present invention. The coordinate input device shown in FIG. 1A has a display 11 'having a display system such as a dot matrix system.
Together with this, an information input / output device for characters, figures, images, etc. is configured.

In the figure, reference numeral 8a is a vibration transmission plate made of acrylic, glass plate, or the like, and transmits the vibration transmitted from the vibration pen 3 to the vibration sensor 6 provided at three peripheral portions thereof.

In the coordinate detection using the vibrating pen in the present embodiment, the transmission time of the ultrasonic vibration transmitted from the vibrating pen 3 to the vibration sensor 6 via the vibration transmitting plate 8a is measured to measure the vibration transmitting plate 8a of the vibrating pen 3 on the vibration transmitting plate 8a. Detect the coordinates at.

The vibration transmitting plate 8a is made of synthetic resin or the like as shown in FIG. 1 (B) in order to prevent the vibration transmitted from the vibrating pen 3 from being reflected in the peripheral portion and returning to the central portion. The vibration transmitting plate 8 to which the vibration isolator 7 is attached is supported by the vibration isolator 7.

As shown in the figure, the vibration isolator 7 is formed by arranging a large number of wedge-shaped patterns in the direction of the peripheral edge of the vibration transmission plate 8.
The length a of the wedge-shaped unit shape 7'of one unit is longer than the wavelength of the elastic wave to be transmitted, and the width b in the arrangement direction thereof is shorter than the wavelength. The advantages of such a structure will be described later.

The vibration transmission plate 8 is arranged on a display device 11 ′ such as a CRT (or a liquid crystal display device) capable of displaying dots, and the dots are displayed at the position traced by the vibration pen 3. That is, a dot display is performed at a position on the display 11 ′ corresponding to the detected coordinates of the vibrating pen 3, and the image composed of elements such as points and lines input by the vibrating pen 3 is written on paper. Appears after the locus of the vibrating pen as you did.

Further, according to such a configuration, a menu is displayed on the display 11 ', and the vibrating pen is used to select the menu item, or a prompt is displayed to bring the vibrating pen 3 into contact with a predetermined position. Can also be used.

The vibration pen 3 that transmits ultrasonic vibrations to the vibration transmission plate 8 is
It has a vibrator 4 composed of a piezoelectric element or the like inside, and transmits the ultrasonic vibration generated by the vibrator 4 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 for the vibrator 4 is supplied as a low-level pulse signal from the arithmetic and control circuit 1 in FIG. 1, amplified by a predetermined gain by the vibrator drive circuit 2 capable of low impedance driving, and then the vibrator 4 Applied to.

The electric drive signal is converted into mechanical ultrasonic vibration by the vibrator 4 and transmitted to the diaphragm 8 via the horn unit 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 driving the vibrator, the second
A vibration mode in which the vibrator 4 mainly vibrates in the vertical direction in the figure is selected. 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 an advantage that it is less susceptible to scratches and obstacles on the surface of the vibration transmitting plate 8 as compared to surface waves.

Again, in FIG. 1 (A), the vibration sensor 6 provided at the corner of the vibration transmission plate 8 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, and the vibration pen 3
The coordinate position on the vibration transmission plate 8 is detected.

The detected coordinate information of the vibrating pen 3 is processed in the arithmetic and control circuit 1 according to the output system by the display 11 '. That is, the arithmetic control circuit controls the output operation of the display device 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 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.

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

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 timing information of the detection signal for measuring the vibration transmission time for 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 in the latch circuit 14 corresponding to each vibration sensor 6, 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 this.

The output control processing of the display 11 'is performed via the input / output port 17.

FIG. 4 illustrates a detection waveform input to the waveform detection circuit 9 of FIG. 1 and a vibration transmission time measuring process based on the detection 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.

The time corresponding to the distance to the vibration sensor 6 in the vibration transmission plate 8
After traveling through tg, the vibration reaches the vibration sensor 6. Reference numeral 42 in FIG. 4 indicates a signal waveform detected by the vibration sensor 6. In the plate wave used in the present embodiment, the relationship between the envelope 421 of the detected waveform and the phase 422 changes according to the vibration transmission distance.

Here, the speed at which the envelope advances is defined as the group speed Vg, and the phase speed is defined as 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 speed is V
g, and when a point on a certain specific waveform, for example, a peak is detected as indicated by reference numeral 43 in FIG. 4, the distance d between the vibration pen 3 and the vibration sensor 6 is d = Vg with its vibration transmission time being tg. .Tg (1) This equation relates to one of the vibration sensors 6, but the same equation can indicate the distance between the other two vibration sensors 6 and the vibration pen 3.

Further, in order to determine the coordinate value with higher accuracy, processing based on the detection of the phase signal is performed. Phase waveform 42 in Fig. 4
If the time from the application of the vibration to the zero cross point after the peak is passed at 2 specific detection points is tp, the distance between the vibration sensor and the vibration pen is d = n · λp + Vp · tp (2). Here, λp is the wavelength of the elastic wave, and n is an integer.

From the expressions (1) and (2), the integer n is expressed as n = [(Vg · tg−Vp · tp) / λp + 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 measured.

For measuring 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 above-mentioned amplifier circuit 51.

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

Also, the timing of this Tg signal and the delay time adjustment circuit 57
The phase delay time detection signal Tp is formed by the detection circuit 58 from the original signal delayed by 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. Further, the comparator level supply circuit 56 forms a threshold value for detecting the tp signal 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 it to the detection circuit 57.

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

This signal is detected by the detection circuit 58, which is composed of a comparator.
And is 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 of the vibration sensors 6, and the same circuit is provided for each of the other sensors.
If the number of sensors is generalized to be h, then h detection signals of envelope delay times Tg1 to h and phase delay times Tp1 to h are input to the arithmetic and control circuit 1.

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

As shown in FIG. 6, when the three vibration sensors 6 are arranged at the corners of the vibration transmission plate 8 at the positions S1 to S3, the processes described with reference to FIG. The straight line distances d1 to d3 to the position of the vibration sensor 6 can be obtained. Further, in the arithmetic control circuit 1, this linear distance d1 to d3
Based on, the coordinates (x, y) of the position P of the vibrating pen 3 can be obtained from the Pythagorean theorem as in the following equation.

x = X / 2 + (d1 + d2) (d1-d2) / 2X (4) y = Y / 2 + (d1 + d3) (d1-d3) / 2Y (5) where X and Y are the positions of S2 and S3. This is the distance along the X and Y axes between the vibration sensor 6 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. However, even when the sensor arrangement as shown in FIG. Coordinate values can be determined.

Here, the vibration isolator 7 as shown in FIGS. 1 (A) and 1 (B).
The effect of using this configuration will be described.

As shown in FIG. 1 (B), by forming the vibration-proof material 7 from a series of wedge-shaped unit shapes 7 ′, the direction from the central portion of the vibration transmission plate 8 to the peripheral portion of the vibration transmission plate 8 is increased. The change in acoustic impedance along d can be regarded as the ratio of the area of the mounted portion and the area of the non-mounted portion of the vibration-damping material 7 having vibration absorption properties. Therefore, the acoustic impedance along the direction d gradually decreases as it approaches the peripheral portion of the vibration transmitting plate 8 as shown in the lower part of FIG. 1 (B).

As is well known, the reflected wave is generated at a portion where the acoustic impedance of the medium changes abruptly. Therefore, by using the vibration isolator 7 having the above-described shape, the acoustic impedance change in the peripheral area of the vibration transmission plate 8 can be prevented. Since it can be eliminated, the generation of reflected waves in this region can be greatly reduced or eliminated. Further, according to the above-mentioned configuration, the length a of the wedge portion of the unit shape 7'of the vibration isolator 7 is a.
Since the wavelength is longer than the transmitted wavelength, the acoustic impedance can be reduced at a gradual change rate that can be neglected with respect to the transmitted wavelength, and the reflected wave can be prevented more reliably.

The structure of the vibration isolator 7 may be any structure as long as it gradually changes the acoustic impedance in the direction from the central portion to the peripheral portion on the periphery of the vibration transmission plate 8. For this purpose, as described above, it is sufficient to gradually change the ratio of the area of the attached portion of the vibration isolator 7 to the area of the non-attached portion thereof. The shape of the vibration isolator 7 is shown in FIGS. There are various possibilities as shown.

For example, as shown in FIG. 7, the unit shape of the vibration isolator 7 may be a strip type instead of a wedge type. In FIG. 7, the unit shape has a length of a and a width of b, and these dimensions are determined in the same manner as described above.

According to such a structure, the acoustic impedance is not continuous, but as shown in the lower part of FIG. 7, it is possible to change the acoustic impedance in two steps at the tip and the base of the strip-shaped unit shape 7 ′. Compared with the conventional example as shown in FIG. 11 (A), the change in acoustic impedance can be made gentler,
It is possible to obtain a desired reflected wave preventing effect.

Further, as shown in FIG. 8, it is conceivable to change the length of the strip shape forming the vibration isolator 7 in a plurality of steps such as a1, a2, and a3. With such a structure, the gradual change in acoustic impedance can be brought closer to the continuous change as shown in FIG.

Further, as shown in FIG. 9, striped vibration isolator 7 having different widths may be provided on the periphery of the multiple vibration transmission plate 8. In this case, the width of the vibration isolator 7 is gradually increased from the central portion of the vibration transmission plate 8 toward the peripheral portion.

Even with such a structure, the areas of the mounted portion and the non-mounted portion of the vibration isolator 7 can be gradually changed along the direction d, and the same effect as described above can be obtained.

Further, as shown in FIG. 10, it is conceivable to provide a large number of vibration isolator 7 having a predetermined shape (here, a circle) on the periphery of the vibration transmission plate 8. In this case, if the diameter of the vibration isolator 7 is made larger toward the peripheral portion, the same effect as described above can be obtained by such a structure. In such a structure, each shape of the vibration isolator 7 may be a shape other than a circle.

The vibration isolator 7 may be fixed to the vibration transmitting plate 8 by adhesion, pressure bonding, or any other suitable method. Further, the same effect can be obtained by applying or printing the paint vibration damping material 7 in the above pattern.

[Advantages of the Invention] As is apparent from the above, according to the present invention, the coordinate input for detecting the coordinates of the vibration input point by detecting the vibration input from the vibrating pen by the vibration sensor provided on the vibration transmission plate. In the device, a vibration isolator having a pattern shape in which the areas of the mounted portion and the non-mounted portion change continuously or stepwise in the direction from the central portion to the peripheral portion of the vibration transmitting plate, the peripheral edge of the vibration transmitting plate. The acoustic impedance of the peripheral portion of the vibration transmission plate is changed from the central portion to the peripheral portion because the acoustic impedance is gradually changed in the direction from the central portion to the peripheral portion of the vibration transmission plate. By setting so that the acoustic impedance change occurs gradually, it is possible to reduce the reflected wave that has the characteristic that the acoustic impedance change occurs at a sharp portion. There is an excellent effect that noise at the time of vibration detection can be reduced and the coordinate detection accuracy can be improved.

[Brief description of drawings]

FIG. 1 (A) is an explanatory view showing a configuration of a coordinate input section of an information input device adopting the present invention, and FIG. 1 (B) shows a structure of a vibration isolator of the device of FIG. 1 (A). FIG. 2 is an explanatory view showing the structure of the vibrating pen of FIG. 1, and FIG.
FIG. 4 is a block diagram showing the structure of the arithmetic and control unit shown in FIG. 4, FIG. 4 is a waveform diagram showing detection waveforms for explaining the distance measurement between the vibration pen and the vibration sensor, and FIG. 5 is a waveform detection circuit of FIG. FIG. 6 is a block diagram showing the configuration, FIG. 6 is an explanatory view showing the arrangement of vibration sensors, FIGS. 7 to 10 are explanatory views showing the structure of different vibration isolator, and FIG. 11 (A) is FIGS. 11 (B) and 11 (C) are explanatory views showing a conventional vibration isolator mounting structure, respectively, showing a vibration isolator mounting structure in a conventional coordinate input device. 1 ... Arithmetic control circuit, 3 ... Vibration pen 4 ... Oscillator, 6 ... Vibration sensor 7 ... Vibration isolator, 7 '... Unit shape 8 ... Vibration transmission plate, 51 ... Preamplifier 15 , 16 …… Input port 52 …… Envelope detection circuit 54,58 …… Signal detection circuit 59 …… A / D conversion circuit

Claims (1)

[Claims] 1. A coordinate input device for detecting the coordinates of a vibration input point by detecting a vibration input from a vibration pen by a vibration sensor provided on the vibration transmission plate. A vibration damping material having a pattern shape such that the areas of the mounted portion and the non-mounted portion in the direction toward the direction is continuously or stepwise changed is provided on the periphery of the vibration transmitting plate, and the vibration transmitting plate is provided from the center to the peripheral portion. A coordinate input device characterized in that acoustic impedance is gradually changed with respect to a heading direction.