JPS63284632A - Coordinate input device - Google Patents

Abstract

PURPOSE:To improve the detecting accuracy for a coordinate input device by detecting the angle formed between a vibrations pen and a vibration transmission plate and inhibiting the input of coordinates performed by the vibration pen as long as the angle of this pen is kept within a prescribed range. CONSTITUTION:A horn part 5 formed at the top of a vibration pen 3 is covered with a pen point cover 114 and at the same time held so as not to be brought into contact with the inside of the hollow cover 114. The tip of the part 5 is exposed to the outside through an open part formed at the top of the cover 114. This exposed extent is decided so that a part of the cover 114 is brought into contact with a vibrating plate 8 when the pen 3 is tilted from its vertical position by an angle alpha. Therefore, the tip of the part 5 floats above the plate 8 to inhibit the input of vibrations to the plate 8.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention detects vibrations input from a coordinate input device, particularly a vibration pen, using a plurality of vibration sensors provided on a vibration transmission plate, and transmits vibrations to each vibration sensor. The present invention relates to a coordinate input device that detects input coordinates from vibration transmission time.

[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, figures, 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) A method that detects electromagnetic or electrostatic induction from conductive sheets placed opposite each other.

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

In the above methods 1) and 2), it is difficult to form a transparent tablet because a resistive film or a conductive film is used. On the other hand, in method 3), 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 as if it were writing an image on paper. A good information input/output device can be constructed.

[Problems to be Solved by the Invention] Although the coordinate detection method using ultrasonic vibration has the above-mentioned advantages, there is a problem that the coordinate detection accuracy is easily affected by the usage conditions of the vibrating pen.

FIG. 9 shows the structure of a vibrating pen 3 used in a conventional coordinate input device. A vibrator made of a piezoelectric element or the like is provided inside the vibrating pen 3 , and the vibrations of the vibrator 4 are input to the vibration transmission plate 8 via the horn section 5 .

The vibrator of the vibrating pen 3 is vibrated in the pen axis direction of the vibrating pen 3. In such a structure, a so-called elastic plate wave is generated that causes the entire vibration transmission plate 8 to vibrate in the vertical direction in the figure. Such vibrations have the advantage that they are less likely to be attenuated by scratches on the vibration transmission plate 8, obstacles, and the like.

However, when the vibrating pen 3 is tilted as shown in Figure 10, the input vibration vector M is tilted by the tilt angle of 0, so the component of the input vibration waveform in the direction perpendicular to the vibration transmission plate 8 is as shown in Figure 9. decrease compared to The right side of FIGS. 9 and 10 shows detection waveforms of the vibration sensor depending on the angle of each vibrating pen 3. Since the vibration sensor provided on the vibration transmission plate 8 is provided to detect vibration components in a direction perpendicular to the vibration transmission plate 8, the amplitude of the vibration detection signal is reduced.

Then, when the inclination angle θ exceeds a certain value, the amplitude of the vibration detection signal becomes smaller than the value that allows determining the vibration detection timing, and eventually coordinate detection becomes impossible. The vibrating pen 3 near the limit value of the inclination angle θ
If you use , there is a possibility that an incorrect input will be made that the operator did not intend.

[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 vibration sensors provided on a vibration transmission plate, and each vibration is detected by a plurality of vibration sensors provided on a vibration transmission plate. In a coordinate input device that detects input coordinates from vibration transmission time to a sensor,
A configuration is adopted that includes means for detecting the angle of the vibrating pen with respect to the vibration transmission plate, and means for prohibiting coordinate input by the vibrating pen when the angle of the vibrating pen detected by the detecting means is within a predetermined angular range. did.

[Function] According to the above configuration, coordinate input can be prohibited in a predetermined range where the angle of the vibrating pen with respect to the vibration transmission plate makes coordinate input unstable, and detection accuracy can be improved.

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

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

In the figure, a vibration transmitting plate 8 is made of acrylic, glass, or the like and transmits vibrations 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 vibration transmitting plate 8 has its peripheral portion supported by an anti-reflection material 7 made of silicone rubber or the like in order to prevent vibrations transmitted from the vibrating pen 3 from being reflected at the peripheral portion and returning toward the center. ing.

The vibration transmission plate 8 is disposed on a display device 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. That is, a dot is displayed at a position on the display 11'' corresponding to the detected coordinates of the vibrating pen 3, and an image composed of elements such as points and lines input by the vibrating pen 3 is displayed as if it were written on paper. Appears after the trajectory of the vibrating pen as if it were done.

Moreover, 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. 2 shows the structure of the vibrating pen 3. A vibrator 4 built into the vibrating pen 3 is driven by a vibrator drive circuit 2 shown in FIG.

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. 2 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 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.

The horn section 5 at the tip of the vibrating pen 3 is covered by a pen tip cover 114 in this embodiment.

The pen nib cover 114 is configured integrally with the case of the vibrating pen 3 or separately, and the horn portion 5 is configured as a hollow pen nib cover 1.
4 is held inside so as not to come into contact with the pen tip cover 114.

The tip of the horn portion 5 is exposed to the outside through the opening at the tip of the pen tip cover 114, but the amount of exposure is smaller than that of the vibrating pen 3.
It is determined that a part of the pen tip cover 114 comes into contact with the vibration transmission plate 8 when the pen tip cover 114 is tilted by an angle α from the vertical position as shown in the figure.

Therefore, when the inclination angle of the vibrating pen 3 exceeds α, the tip of the horn portion 5 rises from the vibration transmitting plate 8 and vibration input to the vibration transmitting plate 8 becomes impossible.

This limit angle α setting will be described later as it is related to the coordinate detection process.

At a corner of the vibration transmission plate 8, a vibration sensor 6 composed of a mechanical to electrical conversion element such as a piezoelectric element is provided. The vibration sensor 6 is supported by an external device 13 of the input tablet as shown in FIG.

The outer device 13 supports the end of the vibration transmission plate 8 via the anti-reflection material 7.

As shown in FIG. 1, the output signals of each of the three vibration sensors 6 provided around the vibration transmission plate 8 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. be done. The arithmetic control circuit 1 performs vibration transmission time measurement processing and detects the coordinate position of the vibrating pen 3 on the vibration transmission plate 8.

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 display drive circuit 10 based on the input coordinate information.

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

Here, the structure of the drive system of the vibrating 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 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 obtains timing information of a detection signal for measuring vibration transmission time for coordinate detection and signal level information for pen pressure detection from the output of the vibration sensor 6 as described later. Output. These timing and level information are input to input ports 15 and 16, respectively.

The timing signal input from the waveform detection circuit 9 is input to the input port 15, and the latch circuit 1 is input by the determination circuit 17.
4 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.

Output control processing for the display device 11' is performed via the input/output port 18.

FIG. 4 explains the detected waveform input to the waveform detection circuit 9 of FIG. 1 and the vibration transmission time measurement process based on the detected waveform. In FIG. 4, reference numeral 41 indicates a drive signal pulse applied to the vibrating pen 3. Ultrasonic vibrations transmitted from the vibrating pen 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. 6 Reference numeral 42 in FIG. 4 indicates the signal waveform detected by the vibration sensor 6. ing. 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 vibrating pen 3 and the vibration sensor 6 can be detected from the difference in group velocity and phase velocity.

First, focusing only on the envelope 421, its speed is Vg, and when a point on a certain waveform, for example a peak, is detected as indicated by the reference numeral 43 in FIG. 4, the distance between the vibration pen 3 and the vibration sensor 6 d is the vibration transmission time t
As g, d=Vg-t 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 pen 3 can be indicated by 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·input p+Vp·tp (2). Here, input p is the wavelength of the elastic wave, and n is an integer.

From the above equations (1) and (2), the above integer n is n =
[(Vg・tg−Vp conflict tp) /input p+1/N]
−(3). Here, N is a real number other than O,
Use appropriate numbers. For example, when N=2, n can be determined if it is within the wavelength.

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.

The two vibration transmission times tg and tp shown in FIG. 4 are measured by the waveform detection circuit 9 shown in FIG. The waveform detection circuit 9 is constructed as shown in FIG.

In FIG. 5, the output signal of the vibration sensor 6 is amplified to a predetermined level by a preamplifier circuit 51. 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 detected by a signal detection circuit 54 composed of a mono multivibrator, etc.
The envelope delay time detection signal Tg of a predetermined waveform is
is formed and input to the arithmetic control circuit l.

Further, a phase delay time detection signal Tp is formed by a comparator detection circuit 58 from this Tg multiplied signal and the original signal delayed by the delay time adjustment circuit 57, and a phase delay time detection signal Tp is formed by the arithmetic control circuit l.
is input.

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-h are inputted to the arithmetic control circuit 1, respectively.

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

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

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

x=X/2+(di+d2)(di-d2)/
2X − (4)y = Y/2+(di + d3
) (di-d3)/2Y... (5)
Here, x and Y are 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 31).

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

As described above, coordinate detection is performed according to the envelope of the detection signal of the vibration sensor 6. Therefore, as described in the section on the conventional example, when the inclination angle of the vibrating pen 3 becomes large and the input vibration intensity to the vibration transmission plate 8 is greatly attenuated, coordinate detection becomes impossible.

Therefore, the limit angle α in FIG. 2 set by the nib cover 114 of the vibrating pen 3 depends on the vibration intensity of the vibrator of the vibrating pen 3, the size of the vibration transmission plate 8, the sensitivity of the vibration sensor 6, etc. The angle value is set with some margin for the angle at which envelope detection becomes impossible.

As a result, when the vibrating pen 3 is tilted to a large extent, the pen tip cover 114 can separate the horn section 5 of the pen tip from the vibration transmission plate 8, thereby prohibiting vibration input.

As mentioned above, by setting the angle α with some margin above the limit value at which coordinate detection is completely impossible, reliable coordinate input is always possible within the input angle range of the vibrating pen 3. can be done.

In the above embodiment, the configuration in which the input of the vibrating pen 3 is prohibited by physical means at a predetermined angle or more is exemplified, but it is also possible to prohibit coordinate detection electrically by the structure shown in FIGS. You may also do so.

In the configuration shown in FIG. 7, the pen tip cover 114 of the pen tip of the vibrating pen 3 is slidably supported in a direction parallel to the pen axis with respect to the pen case, and is biased toward the pen tip by a spring 116. has been done. The vibrator 4 and the horn portion 5 are fixed to the pen shaft.

the pen shaft of the pen nib cover 114 by the spring 116;
The supporting position for the horn portion 5 is the same as in FIG. 2.

A arm-like actuator 115 is provided at the rear end of the pen nib cover 114, and this actuator 115
A limit switch 117 is arranged at a rear position. Note that in FIG. 7, reference numeral 4' indicates a cable that provides a drive signal to the vibrator 4.

In the above configuration, when the vibrating pen 3 is tilted by an angle α or more, the pen tip cover 114 comes into contact with the vibration transmission plate 8 and moves backward, and its actuator 115 operates the limit switch 117.

Therefore, by detecting the output of the limit switch 117, it is possible to detect an inclination of the vibrating pen 3 that is greater than or equal to the angle α, and based on this, it is possible to prohibit the coordinate detection process.

In the configuration shown in FIG. 8, a mercury switch 118 is provided as a sensor for detecting the tilt of the vibrating pen 3. The mercury switch 118 is a glass tube filled with mercury.

The mercury switch 118 on the wood flow side can be made by adjusting the amount of mercury 119 inside the switch or the distance between the contacts 120 and 121, so that when the entire switch is tilted at an angle of more than α with respect to the central axis of the switch, The contacts 120 and 121 are configured to conduct through the mercury 119.

The mercury switch 118 is installed inside the vibrating pen 3 so that the central axis of the pen shaft and the central axis of the switch coincide.

Therefore, even in such a configuration, it is possible to extract an angle detection signal indicating the inclination of the vibrating pen 3 at an angle α or more from the contacts 120 and 121 of the mercury switch 118 as in FIG. 7, and based on this detection signal, Coordinate detection processing can be prohibited.

[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 vibration sensors provided on a vibration transmission plate, and the vibration transmission time to each vibration sensor is calculated. In a coordinate input device that detects input coordinates, means for detecting an angle of the vibrating pen with respect to the vibration transmission plate;
If the angle of the vibrating pen detected by this detection means is within a predetermined angle range, a configuration is adopted that prohibits coordinate input by the vibrating pen, so that the angle of the vibrating pen with respect to the vibration transmission plate is input as coordinates. Coordinate input can be prohibited in a predetermined range where the detection becomes unstable, and an excellent advantage can be obtained in that coordinate input can always be performed with good detection accuracy.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the configuration of an information input/output device adopting the present invention, Fig. 2 is an explanatory diagram showing the structure of the vibrating pen shown in Fig. 1, and Fig. 3 is an explanatory diagram showing the structure of the vibrating pen shown in Fig. 1. Figure 4 is a waveform diagram showing the detected waveform explaining the distance measurement between the vibrating pen and the vibration sensor, and Figure 5 is a block diagram showing the configuration of the waveform detection circuit in Figure 1. Figures 6 and 6 are explanatory diagrams showing the arrangement of vibration sensors, Figures 7 and 8 are explanatory diagrams showing different configurations for detecting the angle of the vibrating pen, and Figures 9 and 10 are conventional diagrams. FIG. 2 is an explanatory diagram showing the drawbacks of the vibrating pen. l... Arithmetic control circuit 3... Vibration pen 4... Vibrator 6... Vibration sensor 8... Vibration transmission plate
51... Preamplifier 15.16... Input port 52... Envelope detection circuit 54.58... Signal detection circuit 59... A/D conversion circuit 114... Pen tip cover 115...・Actuator 116...Spring 117...Limit switch 118...Mercury switch 120.121...Contact

Claims (1)

[Claims] In a coordinate input device that detects vibration input from a vibrating pen using a plurality of vibration sensors provided on a vibration transmission plate, and detects input coordinates from vibration transmission time to each vibration sensor, the vibration transmission plate of the vibrating pen 1. A coordinate input device comprising: means for detecting an angle relative to the vibrating pen; and means for prohibiting input of coordinates using the vibrating pen when the angle of the vibrating pen detected by the detecting means is within a predetermined angular range.