JP2503062B2 - Coordinate input device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a coordinate input device, and in particular, a vibration sensor provided on a vibration transmitting plate detects vibration input from a vibrating pen to a vibration transmitting plate to detect vibration of the vibrating pen. The present invention relates to a coordinate input device that detects the coordinates of an input point.

[Prior Art] Conventionally, a coordinate input device using various input pens, tablets, and the like has been known as a device for inputting handwritten characters, graphics, and the like into a processing device such as a computer. From this type of device, the input image information consisting of characters and figures is output to a display device such as a CRT display or a recording device such as a printer.

In this type of device, the ultrasonic vibration transmitted from the vibration input pen to the tablet is input to the vibration transmission plate, and is detected by the vibration sensor provided at a predetermined part of the vibration transmission plate from the input point, and the vibration to each sensor is detected. A configuration is known in which the coordinates of the input point are determined by the transmission time.

In such a method using ultrasonic vibration, the input tablet can be made of not only a transparent material such as an acrylic plate or a glass plate but also a conductive material such as a metal. It is possible to configure an information input / output device that can be used as if writing an image on paper and has a good operational feel. Also, as a normal opaque tablet, without using patterned electrodes,
The information input device can be configured easily and inexpensively.

[Problems to be Solved by the Invention] In the coordinate input device as described above, a piezoelectric element or the like is used as an electric / mechanical element or a mechanical / electrical conversion element forming a vibrator or a vibration sensor. Such a vibration conversion element is fixed to the vibration transmission plate of the tablet or a member such as a horn at the tip of the vibration pen by a method such as adhesion or pressure contact.

In the pressure contact using a spring or the like, an air layer is generated between the element end surface and the surface on which the element is pressure-contacted due to the roughness of the element end surface, and the vibration transfer characteristics also vary even if the pressure-contact condition is managed. In particular, since the electrodes are provided on the end faces of the conversion element, it is difficult to control the shape of the end faces to be constant in a structure in which silver paste or the like is attached, so that the variation in the vibration transfer characteristics becomes large.

Therefore, in the method of determining the vibration detection timing based on the waveform processing and performing the coordinate calculation, an error occurs in the detected coordinate value, and there is a problem that a certain coordinate detection accuracy cannot be secured for each product.

The change in the vibration transfer characteristics occurs at the pressure contact area of the vibrator of the vibrating pen and the pressure contact area of the vibration transfer plate of the tablet and the vibration sensor, so even if the variation in the vibration transfer characteristics at each part is small, the result is as follows. Significant variation in characteristics will occur.

Therefore, it has been proposed to fill grease between the vibration transmission plate and the vibration sensor in order to reduce the variation in the characteristics at the pressure contact portion, but it is necessary to prevent electrical noise or to improve the stability and accuracy of detection. Therefore, each of the vibration sensor and the vibration transmission plate has to be dropped to the ground of the case through another route, which complicates the configuration and deteriorates the assemblability of the device, resulting in a high cost.

 An object of the present invention is to solve the above problems.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, the vibration input from the vibrating pen to the vibration transmitting plate is detected by a vibration sensor provided on the vibration transmitting plate, and In a coordinate input device for detecting the coordinates of a vibration input point, a conductive layer formed on the surface of the vibration transmission plate in an area larger than the contact area of the vibration sensor, and provided between the conductive layer and the electrode of the sensor. We adopted a configuration to obtain continuity with the sensor via a conductive viscous fluid.

[Operation] According to the above configuration, the vibration transmission plate is formed via the conductive layer formed on the surface of the vibration transmission plate and the conductive viscous fluid provided between the conductive layer and the electrode of the vibration sensor. Since the vibration sensor is coupled, either the vibration transmission plate or the vibration sensor may be electrically grounded.

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

FIG. 1 shows the structure of an information input / output device adopting the present invention. The device shown in the figure makes the input tablet composed of the vibration transmission plate 8 perform coordinate input by the vibrating pen 3 and displays the input image on the display 11 'composed of the CRT arranged on the input tablet according to the inputted coordinate information. Is.

In the figure, reference numeral 8 is a vibration transmission plate made of acrylic, glass plate or the like, and transmits the vibration transmitted from the vibration pen 3 to the vibration sensor 6 provided at three corners thereof. In this embodiment, the coordinate of the vibration pen 3 on the vibration transmission plate 8 is 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.

In order to prevent the vibration transmitted from the vibrating pen 3 from being reflected in the peripheral portion and returning toward the central portion, the vibration transmitting plate 8
The peripheral portion thereof is supported by an antireflection material 7 made of silicon rubber or the like.

The vibration transmitting plate 8 is arranged on a display 11 'capable of dot display, such as a CRT or a liquid crystal display, and dot display is performed at a position traced by the vibration pen 3. That is, a dot display is performed 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 written as if on paper. Appears after the locus of the vibrating pen as you did.

Further, according to such a configuration, a menu is displayed on the display 11 'and an input method such as selecting a menu item with the vibrating pen or displaying a prompt to bring the vibrating pen 3 into contact with a predetermined position. It can also be used.

Vibration pen 3 for transmitting ultrasonic vibrations to the vibration transmission plate 8
Has an oscillator 4 formed of a piezoelectric element or the like inside, and transmits the ultrasonic vibration generated by the oscillator 4 to the vibration transmission plate 8 via the horn portion 5 having a sharp tip.

FIG. 2 shows the structures of the vibration pen 3 and the vibration sensor 6.

The vibrator 4 built in the vibrating pen 3 is driven by the vibrator driving circuit 2. The drive signal for the vibrator 4 is supplied as a low-level pulse signal from the arithmetic and control circuit 1 in FIG. 1, amplified by a predetermined gain by the vibrator drive circuit 2 capable of low impedance driving, and then the vibrator 4 Applied to.

The electric drive signal is converted into mechanical ultrasonic vibration by the vibrator 4, and is transmitted to the vibration transmission plate 8 via the horn unit 5.

The vibration frequency of the vibrator 4 is selected to a value that allows the vibration transmission plate 8 to generate a plate wave. Further, when the vibrator is driven, a vibration mode in which the vibrator 4 mainly vibrates in the vertical direction of FIG. 2 is selected for the vibration transmission plate 8. Further, by setting the vibration frequency of the vibrator 4 to the resonance frequency of the vibrator 4, it is possible to perform efficient vibration conversion.

The elastic wave transmitted to the vibration transmitting plate 8 as described above is a plate wave, and has an advantage that it is less susceptible to scratches or obstacles on the surface of the vibration transmitting plate 8 as compared to surface waves.

On the other hand, the ultrasonic vibration transmitted on the vibration transmission plate 8 is input to the vibration sensor 6 provided at the end of the vibration transmission plate 8,
It is converted into an electric signal again. The output of the vibration sensor 6 is input to a waveform detection circuit 9 described later, and waveform processing for coordinate detection is performed.

In the present embodiment, the vibration sensor 6 of the vibration transmission plate 8 is pressed against the vibration transmission plate 8 by a pressure contact load f such as a spring, not by adhesion.

At this time, the vibration sensor 6 is pressed against the vibration transmission plate 8 via the conductive grease 61. The conductive grease 61 has a consistency of 190 to 390 (JIS K2220). The conductive grease 61 is filled between the vibration sensor 6 and the vibration transmission plate 8 by adhering to the pressure contact surfaces when the vibration sensor 6 is pressed.

According to this structure, the conductive grease 61 is filled between the vibration sensor 6 and the vibration transmission plate 8 due to the surface roughness and deformation of the pressure contact surface, so that an air layer is not generated. The substantial vibration transmitting surfaces of both can be brought into close contact with each other. Therefore, ultrasonic vibrations can be efficiently transmitted from the vibration transmission plate 8 to the vibration sensor 6, and efficient energy conversion can be performed. That is, the amplification factor after detection by the vibration sensor 6 can be reduced, and the power consumption can be reduced.

Further, since there is no variation in the adhesion of the vibration sensor 6 and the vibration transmission plate 8 for each product, it is possible to eliminate the variation in the coordinate detection accuracy in the coordinate detection processing based on the waveform processing described later. The member to be interposed between the pressure contact surfaces of the vibration sensor 6 and the vibration transmission plate 8 is not limited to conductive grease, and a compound having similar consistency and conductivity or other fluid having high consistency can be used.

Further, in order to prevent noise and the like, the conductive portion 62 provided for eliminating static electricity of the vibration transmission plate 8 is grounded to the vibration sensor 6 through the conductive grease 61 through the common ground line. It goes without saying that the conductive portion 62 is not limited to the portion in the vicinity of the vibration sensor 6 but may be the entire conductive portion if it is a transparent body such as ITO.

In the above description, conductive grease is used as the material to be interposed between the vibration transmission plate 8 and the vibration sensor 6, but
This material may be a conductive adhesive or the like. In this case, the pressure contact mechanism is not necessary, and the device configuration is simpler and cheaper.

Referring again to FIG. 1, the vibration sensor 6 provided at the corner of the vibration transmission plate 8 is also composed of a mechanical / electrical conversion element such as a piezoelectric element. The output signal of each of the three vibration sensors 6 is input to the signal waveform detection circuit 9 and converted into a detection signal that can be processed by the arithmetic control circuit 1 in the subsequent stage. The arithmetic control circuit 1 performs the measurement process of the vibration transmission time, and detects the coordinate position of the vibration pen 3 on the vibration transmission plate 8.

The detected coordinate information of the vibrating pen 3 is used as the arithmetic control circuit 1.
The display 11 'processes according to the output method. That is, the arithmetic and control circuit uses the input coordinate information to display 11 'through the display drive circuit 10.
Control the output behavior of.

FIG. 3 shows the structure of the arithmetic control circuit 1 of FIG. Here, the structure of the drive system of the vibration pen 3 and the vibration detection system by the vibration sensor 6 is mainly shown.

Microcomputer 11 has an internal counter, ROM and R
Built-in AM. The drive signal generation circuit 12 outputs a drive pulse having a predetermined frequency to the vibration drive circuit 2 shown in FIG. 1, and is activated by the microcomputer 11 in synchronization with the coordinate calculation circuit.

The count value of the counter 13 is latched in the latch circuit 14 by the microcomputer 11.

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

The timing signal input from the signal waveform detection circuit 9 is input to the input port 15 and stored in the storage area in the latch circuit 14 corresponding to each vibration sensor 6, 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 the coordinate calculation is performed based on this vibration transmission time value. At this time, the determination circuit 16 determines whether or not all the timing information for waveform detection from the plurality of vibration sensors 6 has been input, and notifies the microcomputer 11 of this.

The output control processing of the display 11 'is performed by the input / output port 17
Through.

FIG. 4 illustrates a detection waveform input to the signal waveform detection circuit 9 of FIG. 1 and a vibration transmission time measuring process based on the detection waveform. In FIG. 4, reference numeral 41 denotes a drive signal pulse applied to the vibration pen 3. The ultrasonic vibration transmitted from the vibrating pen 3 driven by such a waveform to the vibration transmission plate 8 is
The vibration sensor 6 is detected through the inside.

After traveling within the vibration transmission plate 8 for a time tg corresponding to the distance to the vibration sensor 6, the vibration reaches the vibration sensor 6. Reference numeral 42 in FIG. 4 indicates a signal waveform detected by the vibration sensor 6. In the plate wave used in the present embodiment, the relationship between the envelope 421 of the detected waveform and the phase 422 changes according to the vibration transmission distance.

Here, the speed at which the envelope advances is defined as the group speed Vg, and the phase speed is defined as Vp. From this difference in group velocity and phase velocity,
The distance between the vibration pen 3 and the vibration sensor 6 can be detected.

First, focusing only on the envelope 421, its speed is V
g, a point on a particular waveform, for example, a peak
When detected as indicated by reference numeral 43 in the figure, the distance d between the vibration pen 3 and the vibration sensor 6 is d = Vg · tg (1) with the vibration transmission time being tg. This formula relates to one of the vibration sensors 6. In Although,
The same equation can be used to indicate the distance between the other two vibration sensors 6 and the vibration pen 3.

In order to determine the coordinate value with higher accuracy, processing based on the detection of the phase signal is performed. Phase waveform 42 in FIG.
If two specific detection points, for example, the time from the vibration application to the zero cross point after passing the peak and tp, the distance between the vibration sensor and the vibration pen is d = n.lambda.p + Vp.tp (2). Here, λp is the wavelength of the elastic wave, and n is an integer.

From the expressions (1) and (2), the integer n is expressed as N = [(Vg · tg−Vp · tp) / λp + 1 / N] (3). Here, N is a real number other than 0, and an appropriate value is used. For example, if N = 2 and n is within ± 1/2 wavelength, n can be determined.

By substituting n obtained as described above into the equation (2), the distance between the vibration pen 3 and the vibration sensor 6 can be accurately measured.

In order to measure the two vibration transmission times tg and tp shown in FIG. 3, the signal waveform detection circuit 9 can be constructed as shown in FIG. 5, for example.

In FIG. 5, the output signal of the vibration sensor 6 is amplified to a predetermined level by the above-mentioned amplifier 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 formed into an envelope delay time detection signal Tg having a predetermined waveform by a signal detection circuit 54 composed of a mono multivibrator or the like, and input to the arithmetic control circuit 1.

Also, the timing of this Tg signal and the delay time adjustment circuit
The phase delay time detection signal Tp is formed by the detection circuit 58 from the original signal delayed by 57 and is input to the arithmetic control circuit 1.

That is, the Tg signal is converted into a pulse having a predetermined width by the monostable multivibrator 55. Further, the comparator level supply circuit 56 forms a threshold value for detecting the tp signal according to the pulse timing. As a result, the comparator level supply circuit 56 forms a signal having a level and timing as indicated by reference numeral 44 in FIG. 4, and inputs it to the delay time adjustment circuit 57.

That is, the monostable multivibrator 55 and the comparator level supply circuit 56 are for allowing the measurement of the phase delay time to operate only for a fixed time after the envelope peak is detected.

This signal is a detection circuit composed of a comparator, etc.
It is input to 58 and compared with the detection waveform delayed as shown in FIG. 4, and as a result, a tp detection pulse such as reference numeral 45 is formed.

The circuit shown above is for one of the vibration sensors 6,
The same circuit is provided for each of the other sensors. If the number of sensors is generalized to be h, the envelope delay time Tg1 to h and the phase delay time Tp1 to h are h, respectively.
The individual detection signals are input to the arithmetic control circuit 1.

In the arithmetic control circuit of FIG. 3, the signals Tg1 to h and Tp1 to h are input from the input port 15, and the count value of the counter 13 is fetched into the latch circuit 14 with each timing as a trigger. As described above, since the counter 13 is started in synchronization with the driving of the vibrating pen, the latch circuit 14 receives the data indicating the delay time of each of the envelope and the phase.

As shown in FIG. 6, when the three vibration sensors 6 are arranged at the corners of the vibration transmission plate 8 at the positions S1 to S3, the vibration pen 3 is moved from the position P to each position by the process described with reference to FIG. The straight line distances d1 to d3 to the position of the vibration sensor 6 can be obtained. Further, in the arithmetic control circuit 1, this linear distance d1 ~
Based on d3, the coordinates (x, y) of the position P of the vibrating pen 3 can be obtained from the Pythagorean theorem as follows.

x = X / 2 + (d1 + d2) (d1-d2) / 2X ... (4) y = Y / 2 + (d1 + d3) (d1-d3) / 2Y ... (5) where X and Y are the positions of S2 and S3. Sensor 6 and origin (position S
It is the distance between the sensor 6 of 1) along the X and Y axes.

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

In the above, since it is placed on the display 11 ',
Although the example in which the vibration transmitting plate 8 is made of a transparent material has been shown, it goes without saying that the vibration transmitting plate 8 may be opaque and the vibration transmitting plate 8 without the display 11 'may be made of a conductive material such as metal. At this time, the conductive portion 62 is not necessary, and the vibration transmission plate 8 or the vibration sensor 6 may be directly grounded.

[Effects of the Invention] As is apparent from the above description, according to the present invention, the vibration input from the vibrating pen to the vibration transmitting plate is detected by the vibration sensor provided on the vibration transmitting plate, and the vibration input of the vibrating pen is performed. In a coordinate input device for detecting the coordinates of a point, a conductive layer formed on the surface of the vibration transmitting plate in an area larger than the contact area of the vibration sensor, and a conductive layer provided between the conductive layer and the electrode of the sensor. It employs a configuration that obtains electrical continuity with the sensor through a viscous fluid that is volatile. Therefore, the vibration transmission plate and the vibration sensor are coupled through the conductive layer formed on the surface of the vibration transmission plate and the conductive viscous fluid provided between the conductive layer and the electrode of the vibration sensor. Since the vibration transmission plate or the vibration sensor may be electrically grounded, the structure of the device is simplified, the assembling property is improved, and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the configuration of a coordinate input device adopting the present invention, FIG. 2 is an explanatory diagram showing the structure of the vibration input / output section of FIG. 1, and FIG. 3 is the arithmetic control of FIG. FIG. 4 is a block diagram showing a circuit structure, FIG. 4 is a waveform diagram showing a detection waveform for explaining the distance measurement between the vibrating pen and the vibration sensor, and FIG.
FIG. 6 is a block diagram showing the configuration of the waveform detection circuit in the figure, and FIG. 6 is an explanatory diagram showing the arrangement of vibration sensors. 1 ... Arithmetic control circuit, 2 ... Oscillator drive circuit 3 ... Vibration pen, 4 ... Oscillator 5 ... Horn part, 6 ... Vibration sensor 7 ... Antireflection material, 8 ... Vibration transmission plate 9 …… Signal waveform detection circuit 11 …… Microcomputer 13 …… Counter, 14 …… Latch circuit 15 …… Input port, 16 …… Judgment circuit

Front Page Continuation (72) Inventor Yuichiro Yoshimura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Katsuyuki Kobayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Ryozo Yanagisawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (1)

(57) [Claims] 1. A coordinate input device for detecting a vibration input from a vibrating pen to a vibration transmitting plate by a vibration sensor provided on the vibration transmitting plate to detect coordinates of a vibration input point of the vibrating pen. A conductive layer formed on the surface of the sensor in a larger area than the contact area of the vibration sensor, and electrical continuity with the sensor via a conductive viscous fluid provided between the conductive layer and the electrode of the sensor. And coordinate input device.