JPH02110620A - Coordinate input device - Google Patents

Abstract

PURPOSE:To realize a highly precise coordinate inputting by providing a supporting member in contact directly with a vibration transmission plate at its surface, and making the acoustic impedance of the supporting member different from that of the transmission plate, and setting the vibration damping ratio of it larger than that of the transmission plate. CONSTITUTION:The supporting member 30 is brought into contact with the vibration transmission plate 8 at its surface, and the acoustic impedance of the member 30 is made different from that of the transmitting plate 8, and besides, the vibration damping of the member 30 is set to be larger than that of the transmission plate 8. Accordingly, even though both are brought into contact with each other, vibration energy inputted to the transmission plate 8 by a vibration pen 3 is reflected by the boundary surface of both, and is difficult to be transmitted through the member 30. Besides, a part of the vibration energy transmitted to the member 30 is absorbed and attenuated more quickly because of the material of the member 30 which has the larger damping ratio compared with the transmission plate 8, and does not exercise influence upon the vibration propagating in the transmission plate 8. Therefore, it never distorts the vibration of the transmission plate 8, and never deteriorates the precision of waveform detection.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention detects vibrations input from a coordinate input device, particularly a vibrating pen, using a plurality of sensors provided on a vibration transmitting plate. The present invention relates to a coordinate input device that detects coordinates on the top.

[Prior Art] Coordinate input devices using various input pens, tablets, etc. have been known as devices for manually 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.

The following various methods are known for detecting the coordinates of a tablet in this type of device.

1) A method that detects changes in the resistance value of a sheet material placed opposite the resistive film.

2) Electromagnetic or static electricity such as conductive sheets placed opposite each other 8
A method for detecting conduction.

3) A method that detects ultrasonic vibrations transmitted from the input pen to the tablet.

[Problems to be Solved by the Invention] However, the conventional device as described above has the following drawbacks.

In other words, in the above-mentioned type that uses a resistive film, the uniformity of the resistor directly affects the accuracy of the graphic design, so a resistor with particularly excellent uniformity is required, and its precision resolution requires a relatively expensive Become something. 2 for X coordinate and 2 for Y coordinate
Since two resistive films are required, there is also the drawback that transparency decreases.

In addition, the electric 1ifLJ conductive type has electric wires arranged in a matrix, so it is not transparent, and the original
It is unsuitable for use over a display device, etc.

Furthermore, with conventional coordinate input devices that use ultrasonic vibration,
A method is used that detects the delay time during which vibrations generated by an input pen propagate through a vibration transmission plate and reach a conversion element. In this method, when surface waves are used, if you touch or place an object on the vibration transmission plate when inputting coordinates manually with an input pen, or if there is a scratch on the surface of the vibration transmission plate, There is a drawback that the surface waves cannot pass through that part, the surface waves cannot reach the sensor, and coordinate detection cannot be performed.

On the other hand, for plate waves propagating through a thin plate-shaped object, the above-mentioned phenomenon is not as pronounced as for surface waves, and even if you touch the propagation medium, the vibrations will be somewhat attenuated, but the waves will not pass through. can. Therefore, it goes without saying that in order to construct a human-powered coordinate system using this method, it is possible to perform more stable coordinate detection by using plate waves than by using surface waves.

A plate wave is a wave that propagates through a finite thickness, and is also called a Lamb wave. However, considering the configuration, size, weight, and energy of human vibration (which greatly affects power consumption) of the device, for example, a vibration transmission plate is a wave that propagates through a finite thickness. , if the material is aluminum,
Its thickness ranges from a few tenths of a millimeter to about 2 to 3 mm at most. Therefore, as the coordinate input device becomes larger, the vibration transmission plate also becomes larger, which not only deforms the human power surface greatly when inputting coordinates and impairs operability, but also makes it difficult to maintain mechanical strength permanently. I can't.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, vibrations input from a vibrating pen are detected by a plurality of sensors provided on a vibration transmission plate, and the vibrations of the vibrating pen are transmitted. A coordinate input device for detecting coordinates on a plate is provided with a support member that directly contacts the vibration transmission plate on a surface and supports the vibration transmission plate, and the acoustic impedance of the support member is different from that of the vibration transmission plate, and A configuration is adopted in which the vibration vJ damping ratio of the support member is set larger than that of the vibration transmission plate.

[Function] According to the above configuration, the acoustic impedance of the support member that directly contacts the vibration transmission plate and supports the vibration transmission plate is different from that of the vibration transmission plate, and the vibration damping ratio of the support member is different from the vibration transmission plate. Since it is set larger than the transmission plate,
The amount of vibration energy propagating on the vibration transmission plate that is incident on the support member can be suppressed as much as possible, and even if there is vibration energy that is incident on the support member, it can be quickly attenuated. Furthermore, since the vibration transmission plate is supported by the support member, the strength of the input surface is guaranteed.

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

FIG. 1 shows the overall tFJ construction of a coordinate manpower device employing the present invention. The apparatus shown in FIG. 1 is for inputting coordinates to a human-powered tablet I~ made up of a vibration transmitting plate 8 using a vibrating pen 3.

The vibration transmitting plate designated by reference numeral 8 in the figure transmits the vibration transmitted from the vibrating pen 3 to three vibration sensors 6 provided at its corners.

In this embodiment, the coordinates of the vibrating pen 3 on the vibration transmitting plate 8 are detected by measuring the transmission time of the ultrasonic vibration transmitted from the vibrating pen 3 to the vibration sensor 6 via the vibration transmitting plate 8.

The vibrating pen 3 transmits ultrasonic vibration to the vibration transmitting 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.

A vibrator 4 built into the vibrating pen 3 is connected to a vibrator drive circuit 2.
Driven by. A drive signal for the vibrator 4 is supplied as a low-level pulse signal from the arithmetic and control circuit 1 shown in FIG. 1, and a vibrator drive circuit 2 capable of low-impedance driving
After being amplified by a predetermined gain, the signal is applied to the vibrator 4. electrically transmitted.

The vibration frequency of the vibrator 4 is selected to a value that can generate plate waves in the vibration transmission plate 8. Further, when driving the vibrator, a vibration mode in which the vibrator 4 mainly vibrates in a direction perpendicular to the vibration transmission plate 8 is selected. 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.

FIG. 2 shows a method of supporting a vibration transmission plate of a coordinate input device according to the present invention.

In FIG. 2, 8 is a vibration transmission plate, 7 is an anti-reflection material that prevents vibrations applied manually by the vibrating pen 3 from propagating through the vibration transmission plate 8 and being reflected at the end face, and 31 is a coordinate effective human power area. This is an upper case in which the vibration transmission plate 8 is positioned on the outside of the anti-reflection material 7, and the vibration transmission plate 8 is fixed to the back plate 30 with screws (32). The vibration transmission plate 8 is made of aluminum alloy and has a thickness of several mm or less in order to efficiently transmit plate waves with small input energy.

The support member 30 is in surface contact with the vibration transmission plate 8,
The strength of the vibration transmission plate 8 is guaranteed. Furthermore, in this example,
In order to prevent the support member 30 from adversely affecting the vibration transmission of the vibration transmission plate 8, the acoustic impedance of the support member 30 is set to be different from that of the vibration transmission plate 8, and the vibration damping of the support member 30 is set to be larger. It is.

For this purpose, the support member 30 is made of ABS resin, for example. Since the support member 30 has a significantly different characteristic acoustic impedance ρC (ρ: density, C: sound velocity) compared to the vibration transmission plate 8, even if they are in contact with each other, input to the vibration transmission plate 8 with the vibration pen is not possible. It has the characteristic that vibration energy is reflected at the interface between the two and is difficult to pass through the support member 30.

Furthermore, due to the characteristic of the material of the support member 30 that the damping ratio is larger than that of the vibration transmission plate 8, a small portion of the vibration energy transmitted through the support member 30 is absorbed and attenuated more quickly. It does not have a large effect on the vibrations propagating on the 8. In other words, highly accurate coordinate input is possible without distorting the vibrations on the vibration transmission plate 8 and without deteriorating the accuracy of waveform detection, which will be described later, which determines the vibration detection timing.

In this way, by making the material of the support member 30 different in acoustic impedance ρC and having a larger damping ratio than that of the vibration transmission plate 8, the vibration transmission plate 8 and the support member 3
To provide sufficient strength to the input tablet by minimizing the deformation of the vibration transmission plate 8 even when the input surface is enlarged, without impairing the principle of the coordinate human-powered device based on this method even when the input tablet 0 is brought into contact with the input tablet. I was able to do that.

What should be noted here is that the vibration transmission plate 8 and the support member 30
This means that they are only in contact. That is, from a microscopic perspective, an air layer (gas layer) exists on the contact surface between the two due to unevenness due to surface roughness, and the contact surface between the two is acoustically discontinuous. Therefore,
For example, when bonding them together or filling them with a liquid layer (e.g., water, grease, etc.), a more acoustically matched state results in a loss of vibration energy, i.e., when the vibration transmission plate 8 is connected to the support member. As a result, the amount of vibration energy propagated to 30 increases. Therefore, it is most preferable for the two to be placed in contact with each other, and from a microscopic point of view, by changing the acoustic impedance of the contact area between the two, an acoustic discontinuity point is created and vibration energy loss is minimized. can do.

Note that the vibration transmission plate 8 may be made of glass, and the support member 30 may be made of a transparent material such as acrylic. When using transparent materials for these members, it is possible to place a document at the bottom of a human-powered tablet and use it for tracing purposes, or to place a display device at the bottom of the tablet to display the trajectory manually entered from the tablet. It is possible to do so.

In particular, when using a display device, by displaying handwritten characters, figures, etc. in the same size at the manual position, it is possible to achieve good operability similar to that of writing on paper. Furthermore, it goes without saying that the coupling structure between the support member 30 and the vibration transmission plate 8 is not limited to screwing.

In addition to the above configuration, it is conceivable to set the vibration transmission speed of the support member 30 to be slower than that of the vibration transmission plate 8 by selecting the material and shape of the support member.

If the four-axis transmission speed of the support member 30 is slower than the vibration transmission vj,8, the possibility that the vibrations transmitted through the support member 30 will interfere with the vibrations within the vibration transmission plate 8 can be further reduced.

Referring again to 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. The output signals of each of the three vibration sensors 6 are input to the waveform detection circuit 9 and converted into detection signals that can be processed by the arithmetic control circuit 1 in the subsequent stage. Arithmetic control device 1
performs vibration transmission time measurement processing and detects the coordinate position of the vibration ben 3 on the vibration transmission plate e.

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. Below, vibration detection and coordinate value calculation will be explained.

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 vibration sensor 6 as described later. These timing information are manually inputted to each human-powered boat 15.

The timing signal manually inputted from the waveform detection circuit 9 is manually inputted to the manual boat 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 coordinate calculation is performed using this vibration transmission time value.

FIG. 4 explains the detected waveform manually input to the waveform detection circuit 9 of FIG. 1 and the measurement process of vibration transmission time 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 speed at which the envelope advances 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. Vote 1 fid is d=Vg −t, where tg is the vibration transmission time
g (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
If the time from 22 specific detection points, for example, vibration application to the zero cross point after passing the peak, is tp, then 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, n
is an integer.

From the above equations (1) and (2), the above integer n is n-[(Vg-tg-Vp-tp) /λp +1/
Denoted as Nl-(3). Here, N is a real number other than 0, and an appropriate value is used. For example, if N=2,
If the fluctuation of 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. 4, 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. The peak detection signal is formed into an envelope delay time detection signal Tg having a predetermined waveform by a signal detection circuit 54 composed of a mono multivibrator or the like, and is manually inputted to the arithmetic control circuit 1.

Also, from this T g (a) and the original signal delayed by the delay time adjustment circuit 57, the comparator detection circuit 58
A phase delay time detection signal Tp is formed and input to the arithmetic control circuit 1 manually.

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. 1, the above Tgl~h1Tpl~
The input port 15 is manually inputted 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. Straight line distance nffdl~d to the position of the vibration sensor 6
3 can be found.

Furthermore, the arithmetic control circuit 1 calculates the linear distance 11iLil-d3.
Based on this, the coordinates (x, y) of the position P of the vibrating pen 3 can be determined from the 3-square theorem as shown in the following equation.

x-X/2 + (di * 62Hdl
-d2)/2X -(4)y= Y/2 +(d
i + d3) (di - d3) /2Y
... (5) Here, X and Y are S2. This is the distance along the X and Y axes between the vibration sensor 6 at the position S3 and the sensor at the origin (position Sl).

In the manner 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, vibrations input from a vibrating pen are detected by a plurality of sensors provided on the vibration transmitting plate, and the coordinates of the vibrating pen on the vibration transmitting plate are determined. In the coordinate human-powered device for detecting the
The acoustic impedance of this support member is different from that of the vibration transmission plate, and the vibration damping ratio of the support member is set larger than that of the S transmission plate, so the vibration wave component transmitted to the vibration sensor is transmitted through the support member. By supporting the vibration transmission plate with a support member, the strength in terms of human power is guaranteed. It has excellent effects such as:

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the configuration of a coordinate input device employing the present invention, FIG. 2 is an explanatory diagram showing the configuration of a vibration transmission plate and a support member in the coordinate input device employing the present invention, and FIG. A block diagram showing the structure of the arithmetic control circuit shown in Fig. 4.
The figure is a waveform diagram showing the detection waveform explaining the distance measurement between the vibrating pen and the vibration sensor, Figure 5 is a block diagram showing the configuration of the waveform detection circuit in Figure 1, and Figure 6 is the arrangement of the vibration sensor. FIG. 1... Arithmetic control circuit 3... Vibration pen 4... Vibrator 6... Vibration sensor 8... Vibration transmission plate
51... Preamplifier 15.16... Input capo] 30... Support member 52... Envelope detection circuit 54.58... Signal detection circuit 59... A/D conversion circuit No. Figure 4: East e exposed 1, upper ward, Haruwo no zu'o-7, sword 8 Figure 3: Shuku, 7, am's mouth 7, am's part 7, 8 Figure 5: A heron on ↑? n 7-ri “Suke 2 I 4 Ie, Oki no δ e Month S 6th
figure

Claims (1)

[Claims] 1) In a coordinate input device that detects vibrations input from a vibrating pen using a plurality of sensors provided on a vibration transmitting plate to detect the coordinates of the vibrating pen on the vibration transmitting plate, A support member is provided that contacts and supports the vibration transmission plate, and the support member has an acoustic impedance different from that of the vibration transmission plate, and the vibration damping ratio of the support member is set to be larger than that of the vibration transmission plate. coordinate input device.