JPH01214921A - Coordinate inputting device - Google Patents

Abstract

PURPOSE:To improve the coordinate detecting accuracy by providing a vibration proofing material which absorbs vibrations at prescribed locations on the surface or back of outer margin section of a vibration transmitting plate. CONSTITUTION:A vibration proofing material 7 is fitted to the surface (on both side or one side) of the peripheral section of a vibration transmitting plate 8 and a vibration sensor 6 is mounted between the side margins of the plate 8 surrounded by the material 7. Therefore, the transversal wave component of the vibration inputted from a vibration pen 3 is largely damped by the vibration proofing member 7 mounted on the surface of the vibration transmitting plate 8 and longitudinal elastic waves are detected by means of the sensor 4 in such a state where nearly only the longitudinal waves are detected. Thus influences of the transversal waves can be reduced and the coordinate detecting accuracy can be improved.

Description

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

[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 detecting the coordinates of a tablet in this type of device, a method is known in which ultrasonic vibrations transmitted from an input pen to the tablet are detected. With this method, the tablet can be constructed from a transparent material such as an acrylic plate or a glass plate, so the input tablet can be placed on top of a liquid crystal display, etc., and can be used to input information easily, as if you were writing an image on paper. You can configure output devices.

[Issue 8 to be solved by the invention] Among the methods using ultrasonic vibrations as described above, both methods using transverse wave components transmitted to the vibration transmission plate and methods using longitudinal wave components are known. There is. In the method of detecting longitudinal wave components, the direct wave that reaches the sensor first is detected. If only direct wave components are transmitted through the vibration transmission plate, highly accurate measurements can be performed using the direct waves that arrive first. However, since reflected waves that distort and adversely affect the direct waves are also transmitted, it is necessary to reduce these reflected wave components.

In particular, although transverse elastic waves that occur simultaneously with longitudinal waves have a slower propagation speed than longitudinal elastic waves, the detection level is often higher than that of longitudinal elastic waves, and some of the transverse waves are generated due to reflection at the end face of the vibration transmission plate. In some cases, the mode is converted from to longitudinal wave.
There was a problem in that the reverberation of the transverse elastic wave in the previous cycle interfered with the direct wave in the next cycle, reducing detection accuracy.

Furthermore, regarding direct wave detection, when inputting with a vibrating pen at a short distance from the sensor, there will be interference from transverse elastic waves that are detected slightly later than longitudinal elastic waves, and the detected waveform of longitudinal elastic waves will be distorted and detected. The drawback was that the accuracy decreased.

An object of the present invention is to solve the above problems and provide a coordinate input device that can perform highly accurate coordinate detection.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, longitudinal wave components of vibrations input from a vibrating pen are detected by a plurality of sensors provided on the vibration transmission plate. In a coordinate input device that detects the coordinates of the vibrating pen on the vibration transmission plate based on the transmission time of the longitudinal wave component of the vibration on the transmission plate, vibration is applied to a predetermined position on the outer edge surface or back surface of the vibration transmission plate. A structure with vibration-absorbing damping material was adopted.

[Function] According to the above configuration, the vibration-absorbing material provided at a predetermined position on the outer edge surface or back surface of the vibration transmission plate reduces the level of transmitted vibration of the vibration transmission plate to a large level, and reduces the longitudinal wave component. It is possible to effectively attenuate transverse wave components in the thickness direction that adversely affect the detection of .

[Example 1] The present invention will be described in detail below based on an example shown in the drawings.

FIG. 1(A) shows the structure of an information input/output device employing the present invention. The information input/output device in Fig. 1 is the vibration transmission plate 8.
A display device 1 consisting of a CRT placed over the input tablet according to the input coordinate information is inputted using a vibrating pen 3.
The input image is displayed at 1'.

The vibrating pen 3 has a vibrator 4 made of a piezoelectric element or the like,
This vibrator 4 is driven by a vibrator drive circuit 2.

The reference numeral 8 in the figure is a vibration transmitting plate made of acrylic, glass, etc., which transmits vibrations from the vibrating pen 3 to three vibration sensors 6 installed on the edge (side surface) of the side part. introduce.

In this embodiment, by measuring the longitudinal elastic wave of the ultrasonic vibration transmitted from the horn portion 5 at the tip of the vibrating pen 3 to the vibration sensor 6 via the vibration transmitting plate 8, Find the coordinates of.

Coordinate detection is performed by determining the timing of vibration transmission to the vibration sensor 6 through waveform processing by the waveform detection circuit 9, and measuring the time from when the vibration pen is driven by the vibrator drive circuit 2 until the vibration reaches the vibration sensor 6. The linear distance between the vibrating pen 3 and each vibration sensor 6 is obtained, and further, input coordinate values are detected by geometric calculation.

In order to prevent the influence of reflected waves reflected around the vibration transmission plate 8, the area around the vibration transmission plate 8 is coated with silicone rubber, synthetic resin, or additives such as inorganic compounds and metals mixed therewith to create the desired acoustics. A vibration isolating material 7 provided with impedance is provided. The vibration isolating material 7 is fixed to the surface around the vibration transmission plate 8 except for the area where the vibration sensor 6 is attached by a method such as adhesion. A cross-sectional view of the mounting portion of the surrounding vibration isolating material 7 is shown in FIG. 1(B).

As a result, among the vibrations transmitted from the vibrating pen 3,
In particular, the transverse wave component is attenuated at the peripheral portion where the vibration isolating material 7 is attached, and the reverberation caused by reflection from the end face of the vibration transmission plate is reduced.

Below, the action of the vibration isolating material 7 will be explained in detail.

In this embodiment, a method is adopted in which the vibration sensor 6 detects a longitudinal elastic wave that vibrates in its traveling direction, that is, approximately parallel to the surface of the vibration transmission plate 8, and the vibration input is performed in a direction approximately perpendicular to the vibration transmission plate 8. It will be done. As a result, the transverse wave component input perpendicularly to the vibration transmission plate 8 becomes larger. Even when inputting by tilting the vibrating pen 3, the transverse wave component becomes larger as long as the vibrating pen 3 is not tilted.

Therefore, although it varies depending on the sensor mounting conditions, driving frequency, and thickness of the vibration transmission plate, the amplitude of the elastic wave input to the vibration transmission plate 8 is larger than that of the transverse wave that vibrates perpendicular to the propagation direction.
If this transverse wave component is not sufficiently attenuated, it will be superimposed on the longitudinal wave component that is the object of detection, causing distortion and causing an error in vibration detection timing.

Therefore, by attaching the vibration isolating material 7 to the peripheral surface of the vibration transmission plate 8 as described above, it is possible to effectively attenuate the vibration of transverse waves that vibrate perpendicularly to the propagation direction.

The vibration isolating material 7 may be attached to the back surface of the vibration transmission plate 8, or may be attached to both the front and back surfaces of the vibration transmission plate 8 as shown in FIG. 1(c). can be attenuated more effectively.

On the other hand, the longitudinal wave component is also reflected at the edge of the vibration transmission plate 8 and input to the vibration sensor 6, causing an error in the vibration detection timing. Therefore, in order to attenuate the reflected longitudinal wave, as shown in FIG. A structure may be adopted in which the vibration isolating material 72 is attached to the edge (side surface) in combination with the attachment of the vibration isolating material 71 on the surface of the first embodiment.

In this case, the edge is originally a propagation boundary of the vibration transmission plate 8 as a vibration medium, and the vibration isolating material 7 attached to this side surface
2, considering the absorption efficiency of the vibration of the transmission plate into the vibration isolator,
It is desirable that the acoustic impedance be as close to that of the vibration transmission plate as possible. On the other hand, the vibration isolating material 7 attached to the surface
In order to prevent reflected waves from being generated by the mounting boundary A, the material of the first material should preferably have an acoustic impedance as low as possible, and at least smaller than the acoustic impedance of the vibration isolating material 72 mounted on the edge.

Furthermore, in the above description, the vibration isolating material is attached except for the area where the vibration sensor 6 is attached, but as a method of attaching the vibration isolating material, a structure as shown in FIG. 3 can also be considered.

FIG. 3(A) is a sectional view of the vicinity of the vibration transmission plate 8, and FIG.
B) shows a top view.

In this embodiment, a vibration isolating material 7.7 is attached to the peripheral surface of the vibration transmitting plate 8 (which may be on both sides or one side), and a vibration sensor is attached to the edge of the vibration transmitting plate 8 sandwiched between the vibration isolating materials 7. Attach 6.

In the above configuration, the transverse wave component of the vibration input from the vibrating pen 3 is greatly attenuated by the vibration isolating material 7 attached to the surface of the vibration transmission plate 8, and the vibration sensor 6 detects almost only the longitudinal elastic wave as a direct wave. can be detected and the influence of transverse elastic waves can be reduced.

In addition, the elastic waves that actually propagate through a plate-shaped vibration transmission plate are called plate waves, which are divided into symmetric waves (S waves) whose main components are longitudinal waves and asymmetric waves (A waves) whose main components are transverse waves. It is thought that there are almost no pure longitudinal waves and pure transverse waves. However, in the above configuration, the vibration damping effect in the surface-attached portion of the vibration isolator 7 is greater for the A wave than for the S wave, and in the vibration sensor 6, although the S wave is slightly attenuated, the attenuation of the rest is large. detected at high levels.

FIG. 4 shows a detection waveform A obtained by the vibration sensor 6 when the vibration isolator 7 is not provided near the sensor, and a detection waveform A obtained by the vibration sensor 6 when the vibration isolator 7 is provided near the vibration sensor 6 as shown in FIG. As shown in Figure 6, which shows waveform B obtained in , it can be seen that according to this example, the S wave component that arrives first is hardly attenuated, but the A wave component is effectively suppressed.

Therefore, conventionally, especially when input is made using the vibrating pen 3 at a short distance from the vibration sensor 6, the difference in propagation delay time between longitudinal waves and transverse waves is small, so the longitudinal wave detection wave interferes with the transverse wave, reducing detection accuracy. However, according to the configuration shown in FIG. 3, highly accurate coordinate detection is possible even at short distances.

The structure of the coordinate detection system will be explained in detail below.

The vibration transmitting plate 8 is placed on a display 11' capable of displaying dots, such as a CRT (or liquid crystal display), and displays dots at the position traced by the vibrating pen 3. In other words, a dot is displayed at a position 11 degrees above the display 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 as if written on paper. Appears after the trajectory of the vibrating pen as if it were done.

Further, according to such a configuration, a menu is displayed on the display 11', and an input method such as having the vibrating pen select the menu item or displaying a prompt and touching the vibrating pen 3 at a predetermined position is possible. You can also use

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.

FIG. 5 shows the structure of the vibrating pen 3 in detail. A vibrator 4 built into the vibrating pen 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 signal is applied to the vibrator 4 .

The electrical 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 that can generate plate waves on the vibration transmission plate 8 made of acrylic, glass, or the like. Further, when driving the vibrator, a vibration mode is selected in which the vibrator 4 mainly vibrates in the vertical direction in FIG. 5 with respect to the vibration transmission plate 8. Also, the vibration frequency of the vibrator 4 is set to
Efficient vibration conversion is possible by setting the resonance frequency to .

The elastic wave transmitted to the vibration transmission plate 8 as described above is a plate wave, and as mentioned above, this plate wave includes an S wave, which is a symmetrical wave of mainly longitudinal wave components, and an asymmetric wave, mainly of transverse wave components. a which is a wave
Although S waves are included, this embodiment uses S waves with small dispersion.

Again, in FIG. 1(A), 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 a waveform detection circuit 9, and the timing of vibration arrival at each sensor is detected by waveform detection processing to be described later. This detection timing signal is input to the arithmetic control circuit l.

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 vibrating pen 3 on the vibration transmission plate 8 from this vibration transmission time.

The detected coordinate information of the vibrating pen 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 IO based on the input coordinate information.

FIG. 6 shows the structure of the arithmetic control circuit l shown in FIG.

Here, the structure of the drive system of the vibrating pen 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 FIG. 2A, 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 input to the input ports 15, respectively. A method such as detection using a certain threshold value is used to detect the waveform, but this threshold value may be variably controlled to avoid the influence of pen pressure, vibration transmission distance, etc. Alternatively, other methods that can stably detect waveforms may be used.

A timing signal inputted from the waveform detection circuit 9 is inputted to an input capacitor 15, 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
The output control process of the 0 indicator 11° which informs the 1 is performed via the input/output port 17.

For example, if three vibration sensors 6 are placed at the corners of the vibration transmission plate 8 at positions 53 from SL as shown in FIG.
By the process explained in connection with FIG. 6, the linear pressure fid from the position P of the vibrating pen 3 to the position of each vibration sensor 6 is
ld3 can be obtained. Furthermore, the arithmetic control circuit
Based on this straight line distance d1 to d3, the position P of the vibrating pen 3 is
The coordinates (x, y) of can be determined from the 3-square theorem as follows.

x=X/2+ (d 1 + d2) (d 1 - d2)/
2X...(1) y=Y/2+ (dl+d3)(di-d3)/2Y・
(2) Here, X and Y are the distances along the X and Y axes between the vibration sensor 6 at the positions S2 and S3 and the sensor at the origin (position St).

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, the longitudinal wave component of the vibration input from the vibrating pen is detected by a plurality of sensors provided on the vibration transmission plate, and the vibration on the vibration transmission plate is detected. In the coordinate input device that detects the coordinates of the vibrating pen on the vibration transmission plate based on the transmission time of the longitudinal wave component, a vibration isolating material for absorbing vibration is provided at a predetermined position on the outer edge surface or back surface of the vibration transmission plate. Since this structure adopts a vibration-absorbing material that absorbs vibrations provided at a predetermined position on the outer edge surface or back surface of the vibration transmission plate, the level of transmitted vibration of the vibration transmission plate is large, and the longitudinal wave component can be detected. This has the excellent effect of being able to effectively attenuate the transverse wave component in the thickness direction that adversely affects the image quality, and greatly improving the accuracy of coordinate detection based on the detection of the propagation time of the longitudinal wave component.

[Brief explanation of the drawing]

FIG. 1(A) is an explanatory diagram showing the configuration of a coordinate input device adopting the present invention, FIG. 1(B) is a sectional view of the vicinity of the vibration transmission plate in FIG. 1(A), and FIG. C) is a cross-sectional view when vibration isolating materials are provided on both sides of the vibration transmission plate, Figure 2 is a cross-sectional view showing the structure of the surrounding area of a different vibration transmission plate, and Figure 3 (A) is a further different vibration transmission plate. 3(B) is a top view of the structure of FIG. 3(A), FIG. 4 is a waveform diagram showing the vibration waveform characteristics of the present invention, and FIG. 5 is a sectional view showing the structure of the peripheral part. Figure 1 is an explanatory diagram showing the structure of the vibrating pen, Figure 6 is the
FIG. 7 is a block diagram showing the structure of the calculation control circuit shown in the figure, and FIG. 7 is an explanatory diagram showing the arrangement of vibration sensors. 1... Arithmetic control circuit 3... Vibration pen 4... Vibrator 6... Vibration sensor 7.71.72...
・Vibration isolating material 8... Vibration transmission plate S spout part ] Machi Naru no needle J biting pain;su)

Claims (1)

[Claims] 1) The longitudinal wave component of the vibration input from the vibrating pen is detected by a plurality of sensors provided on the vibration transmission plate, and based on the transmission time of the longitudinal wave component of the vibration on the vibration transmission plate, the vibration transmission plate of the vibrating pen is detected. In a coordinate input device that detects coordinates at
A coordinate input device characterized in that a vibration isolating material for absorbing vibrations is provided at a predetermined position on the outer edge surface or back surface of the vibration transmission plate.