JPS63118824A - Coordinate input device - Google Patents

Abstract

PURPOSE:To detect coordinates with high accuracy by comparing the detecting signal of a vibration sensor with plural threshold levels and controlling the signal processing conditions of the circuits set at the vibration input side or the detecting side based on the result of the comparison. CONSTITUTION:An alarm circuit consists of an LED which supports the operating direction of a switch 21 for vibration pen 3 and changes over the switch 3 to increase the power supply voltage + or -Vcc when the detecting signal level is lower than the lower limit threshold level and then to decrease the voltage + or -Vcc vice versa. In such a way, the signal intensity large enough to detect coordinates can be secure by an output switching action of the pen 3 even in such a case where an obstacle like the paper, etc., exists on a vibration transmitting plate and therefore the vibration has large attenuation. In the same way, an operator can control the output of the pen 3 to obtain the proper signal intensity for detection of coordinates when the signal intensity is too large owing to the writing pressure, etc.

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, and transmits the vibrations of the vibrating pen. This invention relates to a coordinate input device that detects coordinates on a board.

[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) Electromagnetic or static materials such as conductive sheets placed opposite each other
A method to detect ft and J conductors.

3) A method that detects ultrasonic vibrations transmitted from the input vent 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 the method 3), the tablet can be constructed from a transparent material such as an acrylic plate or a glass plate, so that the input tab output device can be constructed on a liquid crystal display or the like.

[Problems to be Solved by the Invention] However, in the above ultrasonic vibration method, obstacles on the vibration transmission plate, such as the operator's finger, paper, or Signal strength may decrease due to dirt, etc. Naturally, the greater the distance between the sensor and the pen, the more the vibrations will be attenuated.Furthermore, the strength of the vibrations that can be detected will vary considerably depending on the operator's pen pressure.

Therefore, especially when the level of the vibration detection signal is significantly reduced due to conditions such as obstacles or pen pressure, coordinate detection may become impossible or detection accuracy may decrease.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, vibration input from a vibrating pen is detected by a plurality of sensors provided on the vibration transmission plate. In a coordinate input device that detects the coordinates of the vibration pen on the vibration transmission plate from the vibration delay time, the detection signal of the vibration sensor is compared with a plurality of threshold values, and depending on the comparison result, the vibration input side or the vibration We adopted a configuration that controls the signal processing conditions on the detection side.

[Function] According to the above configuration, the vibration detection level can be determined in multiple stages, and the signal processing conditions can be adjusted appropriately by taking into account the influence of obstacles on the vibration transmission plate, pen pressure, etc. I can do it.

[Example] The present invention will be described in detail below based on an example shown in one drawing.

FIG. 1 shows the structure of a coordinate input device employing the present invention. The device shown in FIG. 1 not only detects coordinates but also displays input information. In other words, the information input device shown in FIG. In accordance with the information, the input image is displayed on a display 11' consisting of a CRT placed over the input tablet.

In the figure, the one made by Monosha Co., Ltd. indicated by the reference numeral 8 is a vibration transmission plate made of acrylic, glass plate, etc., which transmits the vibration transmitted from the vibrating pen 3 to the vibration sensors 6 provided at three corners thereof. In the example, the coordinates of the vibration transmission plate 8J: of the vibration pen 3 are detected by measuring the transmission time of the ultrasonic vibration transmitted from the vibration pen 3 to the vibration sensor 6 via the vibration transmission plate 8.

The vibration transmitting plate 8 is supported at its periphery by an anti-reflection material 8' made of silicone rubber or the like in order to prevent vibrations transmitted from the vibrating pen 3 from being reflected at the periphery and returning toward the center. has been done.

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. 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 inputted 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.

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. 2(A) 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. The drive signal for the vibrator 4 is supplied as a low-level pulse signal from the arithmetic and control circuit l 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 a direction perpendicular to the vibration transmission plate 8 as shown in FIG. 2(A). Further, by setting the vibration frequency of the vibrator 4 to the resonance frequency of the vibrator 4, efficient vibration conversion is possible.

FIG. 2(B) shows a specific structure of the above-mentioned vibrator drive circuit 2. In this embodiment, the drive voltage of the vibrator of the vibrating pen 3 can be changed to multiple levels by a switch. In Fig. 0, the reference numeral 26 is a buffer amplifier for low impedance drive composed of PNP and NPN transistors and diodes. The child is driven by a drive waveform having an amplitude of +Vcc.

In this embodiment, the power supply voltages +Vcc and -Vcc are connected to the resistor 22.
23 and 24.25 respectively,
The switch 21 allows selection of either ±Vcc or the voltage divided by each resistor as the drive voltage.

That is, in this embodiment, the drive energy of the vibrating pen 3 can be switched between two levels using the switch 21.

It is also conceivable that the switch 21 and the resistors 21 to 25 are constituted by variable resistors or the like. In this case, the input vibration intensity to the vibration transmission plate 8 by the vibrating pen 3 can be continuously varied.

The elastic waves transmitted from the vibrating pen 3 configured as shown in L to the vibration transmission plate 8 are plate waves, and are more affected by scratches, obstacles, etc. on the surface of the vibration transmission plate 8 than surface waves. It has the advantage of being difficult to use.

Again, in 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 6, and are converted into detection signals that can be processed by the subsequent arithmetic control circuit 1. Arithmetic control circuit
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 video signal processing device 10 based on the input coordinate information.

FIG. 3 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 is an internal counter.

Built-in ROM and RAM. The drive signal generation circuit 12 outputs drive pulses of a predetermined frequency to the vibrator drive circuit 2 shown in FIG.
1, it is activated in synchronization with the coordinate calculation circuit.

The count 1 of the counter 13 is latched by the microcomputer 11 into the latch circuit 14.

On the other hand, the waveform detection circuit 9 outputs timing information of a detection signal for measuring vibration transmission time for coordinate detection from the output of the vibration sensor 6 as described later. This timing information is input to the input port 15.

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 16.
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 17.

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 B 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. The reference numeral 42 in FIG. 4 indicates the signal waveform detected by the vibration sensor 6. The plate wave used in this embodiment is a dispersive wave, so it is detected with respect to the propagation distance within the vibration transmission plate 8. The relationship between the waveform envelope 421 and the phase 422 changes during vibration transmission depending on the 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
d=Vg-tg (1) Although this equation relates to one of the vibration sensors 6, the distance between the other two vibration sensors 6 and the vibration pen 3 can be expressed by the same equation.

Furthermore, in order to determine coordinate values with higher precision, the phase waveform 4 shown in FIG.
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 −t p (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 calculated as n= [(vg 11 t g-VpHt p)/input p
+1/Nl... (3) is shown. Here, N is a real number other than 0, and an appropriate value is used. For example, if N=2, n can be determined within ±1/2 wavelength. It is possible to determine n obtained as described above.

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 2, 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, from this Tg times signal, the original signal delayed by the delay time adjustment circuit 57, the comparator detection circuit 58 detects the phase 1! A delay time detection signal Tp is formed and input to the arithmetic control circuit l.

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 each of envelope delay time Tgl-h and phase delay time "rpl-h" are input to the arithmetic control circuit 1.

In the arithmetic control circuit of FIG. 3, the above Tgl-h.

The TP1 to h signals are 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 mentioned above, the counter 13 is started in synchronization with the driving of the vibrator pen. So,
The latch circuit 14 receives data indicating the envelope and phase delay times.

When three vibration sensors 6 are placed at the corners of the vibration transmission plate 8 at positions from St to S3 as shown in FIG.
! By the process explained above, the straight line distance di- from the position P of the vibrating pen 3 to the position of each vibration sensor 6 is
d3 can be obtained. Furthermore, the arithmetic and control circuit 1 can determine the coordinates (X, y) of the position IP of the vibrating pen 3 based on the linear distances di to d3 using the following formula from the 3-square theorem.

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 9131).

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

Furthermore, in the configuration shown in FIG. 5, the envelope detection times If! 1
The amplitude of the envelope detected by 352 is also input to the level detection circuit 71. The level detection circuit 71 is composed of a comparator circuit that compares the input signal with a predetermined threshold value. The level detection circuit 71 compares an input signal with a plurality of threshold values.

That is, in this embodiment, as shown in FIG.
tt and the envelope 821 of the input signal 82 are compared.

If the input value exceeds the upper or lower limit, an alarm circuit 72 consisting of a display, a buzzer, etc. issues an alarm, prompting the operator to switch the switch 21 of the vibrating pen 3.

For example, the alarm circuit 72 is composed of an LED that supports the operation direction of the switch 21 of the vibrating pen 3, and when the detection signal level is lower than the lower limit threshold,
The switch 21 is switched so that cc becomes large, and when the detection signal level is higher than the upper threshold, the power supply voltage Vcc becomes smaller.

With this configuration, even if there is an obstacle such as paper on the vibration transmission plate 8 and vibration attenuation is large, sufficient signal strength for coordinate detection can be obtained by switching the output of the vibrating pen 3. Further, even if the signal strength is too large due to pen pressure or the like, the operator can similarly adjust the output of the vibrating pen 3 to obtain a signal strength suitable for coordinate detection.

In particular, when the detected waveform exceeds the upper threshold value vth, as shown by reference numeral 92 in FIG. Therefore, it is very important to give the above warning. In other words, 1. The vibration transmission plate 8 can be used with an obstacle such as paper placed on it.
This is because if the range of the output level of the vibrating pen 3 is widened, there is a high possibility that an excessive input will be made as shown by reference numeral 92 in FIG.

Although the configuration described above allows the operator to adjust the output of the vibrating pen 3 by a warning, it is also conceivable to automatically change the output of the vibrating pen 3 according to the level of the detection signal. With such a configuration, the operator can concentrate on input work without worrying about adjusting the vibrating pen 3.

FIG. 9 shows an example of a circuit that automatically adjusts the output of the vibrating pen 3. Here, the level detection circuit 71 outputs control signals to the arithmetic control circuit 1 as signals &l 101, 102° 103 according to the level of the detection envelope.

Here, the signal line 101 is for transmitting an enable signal, and in order to cause the arithmetic control circuit l to continue the coordinate calculation as it is, the signal lines 102 and 103 give disable high and disable low signals, respectively. The disable high signal has a detection signal level equal to the threshold value vth
The disable low signal is output when the detection signal level is lower than the threshold V'tl.

When the arithmetic control circuit 1 receives either of the two disable signals, it performs the coordinate arithmetic operation, and when it receives the disable high signal, it lowers the drive voltage of the vibrating pen 3 of the vibrator drive circuit 2. In addition, when a disable low signal is received, control is performed to increase the driving voltage of the vibrating pen 3.The driving voltage of the vibrating pen 3 can be controlled by directly controlling the applied voltage using a transistor, or by using the method shown in FIG. (
The switch 21 in B) may be composed of an analog switch or the like, and this may be switched.

With such a configuration, the output level of the vibrating pen 3 can be controlled with high precision without requiring troublesome operations.

In the above embodiment, the output of the vibrating pen 3 is automatically adjusted according to the detection level, but the same can be done by adjusting the amplification factor of the preamplifier 51 shown in FIG. 5 instead of the output of the vibrating pen 3. effect can be obtained. FIG. 10 shows an example of the circuit at that time. In FIG. 10, the arithmetic control circuit and the level detection circuit 71 are connected in the same way as in FIG. 9.

However, in this case, the arithmetic control circuit 1 controls the gain of the operational amplifier 116 that constitutes the preamplifier 51 instead of the vibrating pen 3.

The preamplifier 51 is composed of an operational amplifier ttS connected as a non-inverting amplifier, and a bias circuit connected to the inverting input terminal of the operational amplifier 116 is controlled by the arithmetic control circuit l via the FET 115.

A resistor circuit 113 that divides the power supply voltage Vcc is connected to the gate of the FETI 15, and the voltage division value of the resistor circuit 113 can be selected by a switch 114. Switching of the switch 114 is controlled by the arithmetic control circuit l.

In the above configuration, when the detection level is too low, the arithmetic control circuit 1 sets the switch 114 to a low voltage on the b side, and switches the FET
The gain of the operational amplifier 116 is increased by reducing the amount of conduction of I15. On the other hand, if the detection level is too high, the switch 114 is switched to the high voltage side to increase the amount of conduction of the FET and lower the gain of the operational amplifier 116.

Even in the above configuration, the same effects as in the case of FIG. 9 can be obtained. In the embodiment shown in FIG. 10 as well, it is conceivable that the gain control is not performed automatically, but that the operator controls the gain of the preamplifier 51 in response to a warning.

Embodiment L shows a configuration in which the input tablet using the vibration transmission plate 8 is stacked on the CRT display 11'', but the input tablet and the display do not need to be placed overlapping in this way, and may be separate units. In addition, the display may be of another display type such as a liquid crystal display.

[Effects of the Invention] As is clear from the above, according to the present invention, the vibration input from the vibrating pen is detected by a plurality of sensors provided on the vibration transmitting plate, and the vibration input from the vibrating pen is detected based on the vibration delay time on the vibration transmitting plate. In a coordinate input device that detects coordinates with a vibration transmission plate, the detection signal of the vibration sensor is compared with a plurality of threshold values, and signal processing conditions on the vibration input side or the detection side are controlled according to the comparison results. Since it adopts a configuration that allows detection levels to be identified in multiple stages, it is possible to perform high-precision coordinate detection by controlling signal processing conditions according to conditions such as pen pressure and obstacles on the vibration transmission plate. A coordinate input device can be provided.

[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 (A) is an explanatory diagram showing the structure of the vibrating pen of Fig. Pen drive circuit diagram,
FIG. 3 is a block diagram showing the structure of the arithmetic and control device shown in FIG. Figure 6 is an explanatory diagram showing the arrangement of the vibration sensor; Figure WIJ7 is a waveform diagram showing detection level identification; Figure 8 is the detected waveform at excessive input. 9 and 10 are block diagrams showing different embodiments of the present invention, respectively. ■... Arithmetic control circuit 3... Vibration pen 4... Vibrator 6... Vibration sensor 8... Vibration transmission plate
15.16...Input port 51...Preamplifier 52...Envelope detection circuit 54.58...Signal detection circuit 59...A/D conversion circuit 71...Level detection circuit 72...・Alarm circuit 91・
... Peak bold circuit 92 ... Addition circuit 93 ... Comparator 116
...Operational amplifier diagram 2 (8) (8 detection paths)! ! Figure 4 Figure 10

Claims (1)

[Claims] 1) Detecting the vibration input from the vibrating pen by a plurality of sensors provided on the vibration transmitting plate, and detecting the coordinates of the vibrating pen on the vibration transmitting plate from the vibration delay time on the vibration transmitting plate. A coordinate input device that compares the detection signal of the vibration sensor with a plurality of threshold values, and controls signal processing conditions of a vibration input side or detection side circuit according to the comparison result. . 2) The coordinate input device according to claim 1, further comprising means for generating a warning prompting an operator to make a predetermined adjustment according to the comparison result of the detection signals of the vibration sensor. . 3) The coordinate input device according to claim 1 or 2, further comprising a control means for adjusting the output of the vibrating pen according to a comparison result of the detection signals of the vibration sensor. 4) Any one of claims 1 to 3, further comprising means for controlling an amplification factor of the output of the vibration sensor according to a comparison result of the detection signals of the vibration sensor. Coordinate input device as described in Section.