JPS63136127A - Coordinate input device - Google Patents

Abstract

PURPOSE:To always detect coordinates with high accuracy by setting a vibration pen at the position of a holding means and setting a constant needed for the detection of coordinates based on the actually measured value of the vibration transmitting time to ensure the proper setting jobs for constants in response to the environmental conditions. CONSTITUTION:When a vibration pen 3 is attached to a holding part 20, a vibration pen detecting signal is produced by an electrode 23 and supplied to an arithmetic control circuit 1. The circuit 1 performs following arithmetic processes to set constants. That is, the known distance (d) between the vibration input position of the part 20 and a detecting sensor 6 is divided by the detected vibration transmitting time. Thus a constant Vg is obtained. While constants Vp and lambdap are obtained from the leading and trailing zero crosses of a detected waveform and the distance (d). Such obtained constants are used for coordinate arithmetic to correct a detection error caused by the change of vibration transmitting characteristics dependent mainly on the temperature change.

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 transmission plate, and determines the vibration delay time on the vibration transmission plate. The present invention relates to a coordinate input device for detecting the coordinates of the vibrating pen on the vibration transmission plate.

[Prior Art] Coordinate input devices using various input pens, tablets, etc. have been known as devices for inputting handwritten characters, figures, etc. to processing devices such as computers. 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 used as if it were writing an image on paper. It is possible to configure an information input/output device that is easy to operate.

[Problems to be Solved by the Invention] However, the above-mentioned ultrasonic vibration method has a problem in that vibration detection accuracy and coordinate detection accuracy based thereon decrease or vary due to changes in vibration transmission characteristics due to environmental conditions, especially temperature. was there. For example, the vibration transmission speed of glass used as a vibration transmission plate does not vary greatly, but fluctuations in the resonant frequency of piezoelectric elements used in vibrating pens and vibration sensors have a large effect on the group velocity and phase velocity of the transmitted vibration. Therefore, the measurement accuracy of vibration propagation time based on phase detection and envelope detection is also affected by this.

[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 the vibration transmission plate, and vibrations on the vibration transmission plate are detected. A coordinate input device for detecting coordinates of the vibrating pen on a vibration transmission plate from a delay time, comprising: means for holding the vibrating pen at a predetermined position on the vibration transmission plate so as to be able to input vibration; The vibration sensor detects the vibration of the vibrating pen, measures the vibration transmission time under predetermined conditions, and determines the constant necessary for the coordinate detection based on the detected vibration.

[Function] According to the above configuration, by placing the vibrating pen at the position of the holding means, the constant necessary for coordinate detection is set based on the actual measurement of the vibration transmission time. By setting constants, accurate coordinate detection can be performed at all times.

[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 device shown in FIG. 1 not only detects coordinates but also displays input information. That is, the illustrated information input device inputs coordinates using a vibrating pen 3 to an input tablet consisting of a vibration transmitting plate 8, and inputs coordinates manually. 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 number 8 indicates a vibration transmitting plate made of acrylic, glass, etc., which transmits the vibrations transmitted from the vibrating pen 3 to three vibration sensors 6 installed at its corners. In the example, the coordinates of the vibrating pen 3 on the vibration transmitting plate 8 are detected by measuring the transmission time of ultrasonic vibrations transmitted from the vibrating pen 3 to the vibration sensor 6 via the vibration transmitting plate 8.

The vibration transmitting plate 8 has a reflective anti-reflection material made of silicone rubber or the like on its peripheral portion in order to prevent the vibrations transmitted from the vibrating pen 3 from being reflected at the peripheral portion and returning toward the central portion.
It is supported by F material 7.

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 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.

FIG. 2('A) shows the structure of the vibrating pen 3.

As shown in the figure, the vibrating pen 3 has a case shaped like a pen shaft,
A horn portion 5 is fixed to its tip. The horn section 5 has an exponential shape in order to efficiently transmit the vibration of the vibrator 4 to the vibration transmission plate 8. That is,
The cross-sectional area of the horn portion 5 is configured to change exponentially from the root toward the tip. In addition, the horn part 5
The acoustic impedance of is set so as to form a resonant system with the vibrator 4.

The vibrator 4 of the vibrating pen 3 is driven by a vibrator drive circuit 2 at a predetermined frequency.

An electrical drive signal generated by the drive circuit 2 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.

The elastic waves transmitted from the vibrating pen 3 configured as described above to the vibration transmission plate 8 are plate waves, and are less susceptible to scratches on the surface of the vibration transmission plate 8, obstacles, etc. than surface waves. It has the advantage of

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 display drive circuit 10 based on the input coordinate information.

Furthermore, a vibrating pen holder 20 is provided at a corner of the vibration transmitting plate 8 where the vibration sensor 6 is not provided. This holding section 20 holds the vibrating pen 3 at a predetermined position on the corner of the vibration transmitting plate 8 with the horn portion 5 at the tip in contact with the surface of the vibration transmitting plate 8, and inputs vibration.

It is used to perform constant setting processing for coordinate detection, which will be described later, and has a structure as shown in FIGS. 2(B) and 2(C).

2(B) shows the vibration transmission plate 8 from the horizontal direction, and FIG. 2(C) shows the holding part 20 in an enlarged manner.As shown in both figures, the holding part 20 is integrally formed from a material such as plastic, and has a concave portion with a shape almost similar to the tip of the vibrating pen 3. The vibrating pen 3 is held in an upright position, and the horn portion of the tip is brought into contact with the vibration transmission plate 8. let When the vibrating pen 3 is driven while set in the holding part 20 as shown in FIG. By detecting this and measuring the vibration transmission time, constant setting processing, which will be described later, can be performed. Second
As shown in FIG.
d is set as an error within 1/2 wavelength of the vibration wavelength used for detection.

In addition, in order to perform a constant setting process to be described later in response to the attachment of the vibrating pen 3 to the holding part 20, an electrode 23 is installed to detect the attachment of the vibrating pen 3 to the holding part 20, as shown in FIG. 2(C).
is provided. This electrode 23 functions as a sensor for the vibrating pen 3, and a vibrating pen detection signal from the electrode 23 is input to the arithmetic control circuit 1.

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

The microcomputer 11 includes an internal counter, ROM, and RAM. The microcomputer 11 provides a start signal to the drive signal generation circuit 12 to start driving the vibrator drive circuit 2, and also provides a counter 13 for measuring vibration transmission time in synchronization with the start of vibration.
Start.

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 for coordinate detection from the output of the vibration sensor 6 as described later.

The timing signal input from the waveform detection circuit 9 is input to the input capacitor 15, and the latch circuit 1 is determined by the determination circuit 16.
It is compared with the count value in 4 and the result is transmitted to 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.

Control processing for the appearance of the display device 11' is performed via the turnout board 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, 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. 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, let the speed at which the envelope advances be group velocity Vg and the phase velocity 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, focusing 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 the reference numeral 43 in FIG. d is the vibration transmission time t
As g, d=Vg0t g m-II (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 indicated by the same equation.

Furthermore, in order to determine coordinate values with higher precision, it is necessary to process the phase waveform 4 in Fig. 4 based on the detection of the phase signal.
22 specific detection points, for example, if the time from vibration application to the zero cross point after passing the peak is tp, the distance between the vibration sensor and the vibration vent is d = n * input p + vP @ tP (2) , where 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 =
[(v g 11 t g −V p 11
t P )/input p+l/Nl (3). Here, N is a real number other than O, and an appropriate value is used. For example, if N=2, n can be determined within ±1/2 wavelength. n obtained as described above can be determined.

By substituting n obtained as described above into equation (2), the distance between the vibration vent 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.

Furthermore, a phase delay time detection signal TP is formed by a comparator detection + circuit 58 from this −Fg multiplied signal and the original signal delayed by the delay time adjustment circuit 57.
It is 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 having an envelope delay time tgl-h and a phase delay time tpl-h are input to the arithmetic control circuit l.

In the arithmetic control circuit of FIG. 3, the above tgi-h, tpl-
The h signal is input from the input capo) 15, and the count value of the counter 3 is taken into the latch circuit 14 using each timing as a trigger.As mentioned above, the counter 3 is started in synchronization with the driving of the vibrator pen. Therefore, the latch circuit 14 takes in 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. The straight-line distance di-d3 to the position of the vibration sensor 6 can be determined. Furthermore, the arithmetic control circuit 1 calculates the coordinates (X,
y) can be obtained from the 3-square theorem as shown in the following equation.

x=X/2+ (dl+d2)(di-ci2)/2X
...(4) y=Y/2+ (dl+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 1ilsl).

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

In the above configuration, a method for measuring vibration transfer characteristics depending on environmental conditions and utilizing the measurement for coordinate calculation will be described.

According to experiments, the temperature change in the vibration transmission speed in glass is about 0.00%/°C for 1 mm thick glass, and the change in the resonant frequency of the piezoelectric element is 0.3%/°C.

As can be seen from the above data, the vibration transmission speed change depending on the glass temperature can be almost ignored, but the vibration transmission speed of the glass depends on the glass thickness t and the frequency f due to the change in the resonance frequency of the piezoelectric element. The product changes as shown in Figure 7.

For example, 20
Assuming that there is a change in temperature, the resonant frequency f changes by 6%. As is clear from FIG. 7, when the product f-t of thickness t and frequency f changes by 6%, the vibration transmission speed changes by 1%. That is, when the distance between the vibrating pen 3 and the vibration sensor 6 is substantially 100 mm, an error of l mya appears.

When the group velocity Vg, phase velocity Vp, and wavelength λp are set as fixed values obtained by measurement in advance, the error increases as the distance between the pen and the sensor increases.

Therefore, in this embodiment, the values of the constants Vg, Vp, and λP necessary for the above coordinate determination are actually measured and used for the coordinate calculation.

To measure these constants Vg, Vp, and input P, the power of the device is turned on, normal vibration detection is enabled, and the operator attaches the vibrating pen 3 to the holder 20. vibrating pen 3
is attached to the holding part 20, the electrode 23 of FIG. 2(C)
A vibrating pen detection signal is formed and input to the arithmetic control circuit l.

The arithmetic control circuit 1 performs the above-mentioned constant setting process by performing the following arithmetic processing.

Vibration input position of the holding part 20 and distance gid of the detection sensor
Since this is known, Vg can be found by dividing this distance d by the detected vibration transmission time. That is, Vg=d/lg (6).

Next, regarding λp in equation 2), if the rising zero cross of the detected waveform is tpr and the falling zero cross is tpf, then input p = Vp - 21 tpr - tpfl...' (7)
d=neVp*Tp+Vp*, tp...(8), where n is the vibration sensor 6 used for measurement with an accuracy of within ±172 wavelengths, as described above regarding equation 3). If the distance between the vibration sensors 6 is maintained, a known value n corresponding to the distance between the vibration sensors 6 measured in advance can be used. Therefore, vp, input p is Vp= d/ (n 11Tp+t p)”
(9) Input p=d・Tp/ (n−Tp+tp) ・・
(10), and from equations 6), 7), and 8), Vg, Vp,
You can find the input P.

By using the constants Vg, Vp, and input p obtained in the above manner in the coordinate calculation described above, it is possible to correct detection errors due to vibration transfer characteristic changes that mainly depend on temperature changes.

According to the above configuration, the operator holds the vibrating pen 3 on the holding part 20.
By simply setting it in the position, constants can be automatically set based on actual measurements of vibration transmission time, allowing accurate coordinate detection regardless of environmental conditions.

Various embodiments can be considered regarding the timing of performing the constant setting process or the method of shifting the process to the constant setting mode.

For example, instead of providing the sensor of the vibrating pen 3 as shown in FIG. 2(C), as shown in FIGS. Only 1
By arranging the distance gId in a position where only the vibration input point appears, when this distance gId is detected as the linear distance between the sensor and the vibration input point using the above-mentioned procedure, it is possible to detect the attachment of the vibrating pen 3 to the holding part 20, and the constant One possible method is to shift to setting mode. 8 shows the case where the vibration sensor 6 is provided at the corner of the vibration transmission plate 8 as described above, and FIG. 9 shows the case where the vibration sensor 6 is provided at the center of the side of the vibration transmission plate 8. In the method shown in FIGS. 8 and 9, the sensor 6 at the origin position
It is also possible to consider a configuration in which the mode is shifted to the constant setting mode when the distance d is detected for a certain period of time or more. According to such a method, there is no problem that the mode is unnecessarily shifted to the constant setting mode due to noise or the like.

When performing the above measurements and constant setting, it is preferable to use the same piezoelectric elements for both the vibrating pen 3 and the vibration sensor in order to make the vibration input conditions of the piezoelectric elements as equal as possible.

In the above embodiment, the input tablet formed by the vibration transmission plate 8 is stacked on the CRT display 11', but the input tablet and the display do not need to be arranged in such a way, but can be separated. Alternatively, 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 transmission plate, and the vibration input from the vibration pen is detected based on the vibration delay time on the vibration transmission plate. A coordinate input device for detecting coordinates on a vibration transmission plate, comprising: means for holding the vibrating pen at a predetermined position on the vibration transmission plate so as to be able to input vibration; The structure includes a means for detecting the vibration with the vibration sensor, measuring the vibration transmission time under predetermined conditions, and determining constants necessary for the coordinate detection based on this, so that the vibrating pen can be moved to the position of the holding means. It is possible to set the constants necessary for coordinate detection by actual measurements simply by placing the device in the input device, and it is possible to provide an excellent coordinate input device that can perform highly accurate coordinate detection regardless of environmental conditions.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the configuration of an information input/output device employing the present invention, FIG. 2 (A) is an explanatory diagram showing the structure of a vibrating pen according to the present invention, and FIGS. ) is an explanatory diagram showing the structure of the holding part of the vibrating pen, Fig. 3 is a block diagram showing the structure of the arithmetic control circuit in Fig. 1, and Fig. 4 explains distance measurement between the vibrating pen and the vibration sensor. 5 is a block diagram showing the configuration of the waveform detection circuit of FIG. 1, FIG. 6 is an explanatory diagram showing the arrangement of the vibration sensor,
FIG. 7 is a diagram showing changes in vibration transmission characteristics, and FIGS. 8 and 9 are explanatory diagrams showing modifications of the present invention, respectively. l... Arithmetic control circuit 3... Vibrating pen 4... Vibrator 5... Horn part 6... Vibration sensor 8
... Vibration transmission plate 22 ... Holding section 23 Electrode 15 ... Input boat 51 ... Preamplifier 52 ...
・Envelope detection circuit 54.58...Signal detection circuit

Claims (1)

[Claims] A coordinate input device that detects vibrations input from a vibrating pen using a plurality of sensors provided on a vibration transmitting plate, and detects coordinates of the vibrating pen on the vibration transmitting plate from a vibration delay time on the vibration transmitting plate. means for holding a pen at a predetermined position on the vibration transmission plate so as to be able to input vibration; and a means for detecting vibration of the vibrating pen held by the holding means with the vibration sensor and measuring a vibration transmission time under predetermined conditions. A coordinate input device characterized by comprising means for determining a constant necessary for the coordinate detection based on the coordinates.