JPH01191921A - Coordinate input device - Google Patents

Abstract

PURPOSE:To improve the operability of a coordinate input device by detecting the difference of the arrival delay time between the horizontal and vertical wave components of different transmission speeds. CONSTITUTION:An information input/output device performs the input of coordinates to an input tablet consisting of a vibration transmitting plate 8 via a vibration pen 3. Based on this input of coordinates, an input picture is displayed on a display device 11 put on the input tablet. The plate 8 transmits the vibrations received from the pen 3 to three vibration sensors set at the corner parts. These transmission time of vibrations are measured for detection of coordinates. The elastic waves transmitted into the plate 8 consist of the horizontal and vertical wave components which have different transmitting speeds despite the same frequency. Thus the waveform of a detection signal contains a vertical waveform WL arriving first the sensor 6 and a slow horizontal waveform WS. Then the transmission speeds of both waves are previously measured so that the coordinate position is detected from the difference of arrival time between both waves.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention detects elastic wave vibrations input from a coordinate input device, particularly a vibrating pen, using a plurality of sensors provided on a vibration transmission plate, and transmits the vibrations from the vibrating pen. The present invention relates to a coordinate input device that detects the coordinates of a vibration input point by a vibrating pen based on the transmission time of elastic wave vibration input to a plate.

[Prior Art 1] 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.

[Problem to be solved by the invention] However, these conventional devices have the following drawbacks.

That is, in the above-mentioned type using a resistive film, the uniformity of the resistor directly affects the precision of graphic input, so a resistor with particularly excellent uniformity is required, which makes it very expensive. Furthermore, since two resistive films are required, one for the X-coordinate and one for the y-coordinate, there is also the drawback that transparency is reduced.

Next, the type that uses electromagnetic induction has electric wires arranged in a matrix, so it is not transparent and is not suitable for use over a document, display, etc.

Furthermore, in conventional ultrasonic coordinate input devices, the delay time required for the vibration generated by the input pen to propagate through the propagation medium and reach the conversion element is detected; In order to detect this, it was necessary to know the reference time (for example, the time when vibration occurred in the input pen), and this information had to be input into a circuit that constantly detects the arrival delay time.

Therefore, the input pen is connected to the main body by a cable or the like, and when inputting characters, figures, etc. using this coordinate input device, operability is extremely poor.

Furthermore, if the signal is transmitted by radio waves, etc., a transmitter or the like must be built into the pen, and it is difficult to achieve the same shape, weight, and operability as a normal writing instrument.

However, if the above-mentioned problems are overcome, the ultrasonic method does not have the drawbacks of the other methods mentioned above, and since the mechanical structure is relatively simple, a low-cost device can be provided. Therefore, it is an object of the present invention to provide a coordinate input device using ultrasonic vibrations, which is a wireless input pen, in particular, which does not require any signal exchange with the tablet side.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, elastic wave vibrations input from a vibrating pen are detected by a plurality of sensors provided on a vibration transmission plate, and vibrations from the vibrating pen are detected. In a coordinate input device that determines a vibration transmission distance based on the transmission time of an elastic wave vibration input to a transmission plate and detects the coordinates of a vibration input point by a vibrating pen, transverse waves and longitudinal waves of elastic waves on the vibration transmission plate are used. A configuration is adopted that includes means for detecting each component, and means for determining the transmission distance of input elastic wave vibration from the difference in arrival delay time of these transverse wave components and longitudinal wave components to the vibration sensor, and performing coordinate calculation.

[Function] According to the above configuration, by detecting the difference in the arrival delay time of transverse wave and longitudinal wave components having different propagation speeds, the vibration transmission time from the input point to the vibration sensor, and therefore the transmission distance, is determined, and the vibration Coordinate calculations can be performed without requiring input timing information.

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

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 to an input tablet consisting of a vibration transmitting plate 8 using a vibrating pen 3, and displays a display 11 consisting of a CRT placed over the input tablet according to the input coordinate information. It displays the input image.

In the figure, the reference numeral 8 denotes a vibration transmission plate made of acrylic, glass, etc., which transmits vibrations transmitted from the vibrating pen 3 to vibration sensors 6 provided at three corners thereof. 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 coordinates of the vibrating pen 3 on the vibration transmitting plate 8 are detected.

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 rA11 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.

Further, according to such a configuration, a menu is displayed on the display 11, and input methods such as having the vibrating pen select the menu item or displaying a prompt and touching the vibrating pen 3 at a predetermined position can be performed. It can also be used.

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.

The vibrating pen 3 has a built-in drive circuit 2 for driving the vibrator 4 and a power source B consisting of a battery, etc., and sends and receives electrical synchronization signals to and from an input tablet or the main body of the device as in the past. I don't.

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.

Further, by setting the vibration frequency of the vibrator 4 to the resonance frequency of the vibrator 4, efficient vibration conversion is possible.

The vibration sensors 6 provided at the corners of the vibration transmission plate 8 are also constituted by mechanical to electrical conversion elements such as piezoelectric elements. The output signals of each of the three vibration sensors 6 are input to the waveform detection circuit 9, and are converted into detection signals that can be processed by the arithmetic control circuit 1 at the subsequent stage. 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 video signal processing device 10 based on the input coordinate information.

FIG. 2(A) shows a vibrator drive waveform for driving the vibrator 4 in the vibrating pen 3. The vibration generated by the vibrator 4 is input to the vibration transmission plate 8.

This vibration is transmitted to the vibration transmission plate 87 as an elastic wave vibration and detected by the vibration sensor 6. The output waveform of the vibration sensor 6 is shown in FIG. 2(B).

Here, the elastic wave propagating in the elastic medium consists of longitudinal wave and transverse wave components. Even if these components have the same frequency, they have different propagation speeds in the medium.For example, if we compare a longitudinal wave and a plate wave whose main component is a transverse wave, the propagation speed of the latter is approximately half that of the former. It has become.

Therefore, as shown in the figure, the detection signal waveform is composed of a longitudinal wave waveform WL that reaches the sensor first, and a waveform WS whose main component is a transverse wave with a slow propagation speed. Here, the propagation velocity of longitudinal waves is VL, and the propagation velocity of transverse waves whose main component is transverse waves is vS.

In addition, both waves are transmitted from the vibrating pen 3 to the part where the vibration sensor 6 is located.
Let tL and ts be the time it takes to reach the point, respectively, and let d be the distance between the vibrating pen 3 and its vibration sensor, then Δt=ts-tL (Δt: difference in arrival time)...(
1) d = VL-tL=VS-tS=VS-(tL+Δ
t)-(2) From the above formula, VL -t L=VS -(t L+At)(
ML-VS)-t L=VS-At L-VS This equation (3) can be expressed as This shows that there is no need to know the input timing.

Therefore, in advance, the longitudinal wave propagation velocity V at the vibration transmission plate 8L is
If L and the transverse wave propagation velocity vS are measured and stored in a memory such as a ROM, the distance between the vibration sensor 6 and the vibration pen 3 can be determined by equation (2).

From the above, the signal waveform detection circuit 9 can be configured from a waveform processing circuit and a timer circuit that detect the arrival timing of the first longitudinal wave component and the next transverse wave component from the output of the vibration sensor 6, and calculate the time difference between them. Recognize.

FIG. 3 shows a time chart of signal processing performed in the signal waveform detection circuit 9. In FIG.

In the figure, reference numeral 31 is a drive waveform for driving the vibrator in the vibrating pen, and reference numeral 32 is a detection signal waveform when the vibration sensor 6 detects the vibration transmitted through the vibration transmission plate. Reference numeral 34 indicates an envelope of the detection signal waveform.

The leading wave of a longitudinal wave can be detected by detecting the rising edge of the detected waveform, but since the leading part of a plate wave whose main component is a transverse wave overlaps with the longitudinal wave, the leading wave cannot be identified. , the shear wave component with large amplitude, and hence the envelope peak of the entire waveform, is treated as the arrival timing of the shear wave. (Accordingly, the arrival time is t's) Therefore, the signal waveform detection circuit 9 specifically includes a circuit such as a comparator for detecting the rising edge of the waveform, and an envelope peak detection circuit. Number 3 in Figure 3
3.34 shows the timing of the detection pulses output by the rise detection circuit and the envelope peak detection circuit, respectively.

Further, the signal waveform detection circuit 9 has a timer circuit for determining the time difference Δt' between these detection pulses.

In this way, the time difference Δt' was found, but since Δt' was not found from the leading wave of the plate wave, it is not the true arrival time difference.The true arrival time difference Δt is Δt=Δt'-α... It is determined by (4). α is a constant, and can be calculated by theoretically determining Δt at a certain distance based on the material of the vibration transmission plate 8, etc., and comparing it with Δt' output at that distance.

The signal waveform detection circuit 9 outputs the above-mentioned Δt to Δt' to the arithmetic control circuit 1 as a latch value of a timer counter or the like. The arithmetic control circuit 1 can calculate the straight line distance from the input point to the vibration sensor 6 based on equation (2) using the constant velocity of the longitudinal and transverse wave components from this time value, and further calculates the orthogonal coordinate value based on this. Obtainable.

When three vibration sensors 6 are arranged at the corners of the vibration transmission plate 8 at the positions indicated by symbols Sl to S3 as shown in FIG.
), these straight-line distances di-d34
From t=, the coordinates (x, y) of the digit 2tP of the vibrating pen 3 can be obtained from the 3 square theorem as shown in the following equation.

x=X/2+ (d 1+d2)(di-d2)/2X
...(5) y=Y/2+ (d1+d3)(dl-d3)/2Y
(6) Here, X and Y are the distances along the x and Y axes between the vibration sensor 6 at the positions S2 and S3 and the sensor at the origin (position Is 1).

The position coordinates of the vibrating pen 3 can be detected in the manner described above. By repeating the above process, input coordinates can be sequentially detected in real time.

As described above, according to this embodiment, coordinate calculations can be performed without the need for the detection device to know the input timing of the vibrating pen, so timing information is exchanged between the device body having the vibration transmission plate and the vibrating pen. The vibrating pen can be made wireless, significantly improving operability during input.

In the above embodiment, the vibration sensor 6 is mounted on the vibration transmission plate 8, but it may also be mounted on the side surface (in the thickness direction) of the vibration transmission plate 8 (see reference numeral 6B in Fig. 5). In the detected signal waveform, the amplitude of the faster longitudinal wave portion is larger, and due to problems such as the S/N ratio, it is easier to detect the leading wave of the longitudinal wave in this case.

In the above, we have considered detecting two waveform components from the output of one sensor. For example, as shown in FIG. The sensor may be attached to the front or back surface and the side surface, respectively, and each component may be detected from these sensors.

These vibration sensors 6A and 6B are composed of piezoelectric elements, etc., and the polarization direction is parallel to the cylindrical axis, and the mode is such that a voltage is mainly output in response to axial displacement. Therefore, the sensor 6A outputs a transverse wave component larger than the longitudinal wave component, and the sensor 6B outputs a larger longitudinal wave component than the transverse wave component. According to this method, the arrival time difference can be directly calculated by detecting the peak value of each component.

In the north, we explained a device that uses a transparent vibration transmission plate to overlap the display or original, but if it is not necessary to use it over the display or original, we can use an opaque material such as metal. You may also use

[Effects of the Invention] As is clear from the above, according to the present invention, elastic wave vibrations input from a vibrating pen are detected by a plurality of sensors provided on the vibration transmission plate, and the elastic wave vibrations input from the vibrating pen to the vibration transmission plate are detected. In the coordinate input device that determines the vibration transmission distance based on the transmission time of the elastic wave vibration and detects the coordinates of the vibration input point by the vibrating pen, means for detecting transverse wave and longitudinal wave components of the elastic wave on the vibration transmission plate, respectively. Since the structure includes a means for determining the transmission distance of the input elastic wave vibration from the arrival delay time difference of the transverse wave component and the longitudinal wave component to the vibration sensor and calculating the coordinates, the propagation velocity is By detecting the difference in arrival delay times of different transverse and longitudinal wave components, it is possible to determine the vibration transmission time and therefore the transmission distance from the input point to the vibration sensor. As a result, there is no need to know the vibration input timing information of the vibrating pen, so the signal exchange between the vibrating pen and the device itself or the input tablet can be omitted, making it possible to use the vibrating pen wirelessly, significantly improving the operability of the device. It has a great effect of improving.

[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 vibrating pen of FIG. ) is a waveform diagram showing the detected waveform by the vibration sensor, Figure 3 is a waveform diagram for explaining the operation and configuration of the signal waveform detection circuit, Figure 4 is an explanatory diagram showing the arrangement of the vibration sensor, and Figure 5 FIG. 2 is an explanatory diagram showing the arrangement of vibration sensors in different embodiments. l... Arithmetic control circuit 2... Vibrator drive circuit 3.
... Vibration pen 4 ... Vibrator 5 ... Horn part 6.6A, 6B ... Vibration sensor 8 ... Vibration transmission plate B ... Power supply 10 ... Video signal processing device 11 ... Display NZ ＾ Book#

Claims (1)

[Claims] 1) The elastic wave vibration input from the vibrating pen is detected by a plurality of sensors provided on the vibration transmission plate, and the vibration transmission distance is determined based on the transmission time of the elastic wave vibration input from the vibration pen to the vibration transmission plate. in a coordinate input device for detecting the coordinates of a vibration input point, means for detecting transverse wave and longitudinal wave components of elastic waves on the vibration transmission plate, respectively;
A coordinate input device comprising means for determining the transmission distance of input elastic wave vibration from the arrival delay time difference between the transverse wave component and the longitudinal wave component at the vibration sensor and performing coordinate calculation.