JPH05150894A - Coordinate input device - Google Patents

Abstract

PURPOSE:To provide an inexpensive coordinate input device which excels in its operability. CONSTITUTION:A vibration pen 3 contains a vibrator driver circuit 2, a vibrator 4 and a driving power supply B which are needed for generation of the vibrations. A vibration transmitter plate 8 serving as a tablet is provided with plural vibration sensors 6. Then a signal waveform detector circuit 9 and an arithmetic control circuit 1 calculate the transmission distances between the sensors 6 and the input point of the pen 3 based on the output signals of the sensors 6. At the same time, a transmission time difference DELTAt containing plural different components of vibration transmission velocities (V1, V2) from the outputs of the sensors 6 is obtained. The distance 1 between the pen 3 and each sensor 6 is shown as 1=V1.V1=V2.t2=V2.(t1+DELTAt). Therefore t1=V2/(V1- V2).DELTAt is satisfied. Thus the distance 1 can be obtained with calculation of the time difference DELTAt. Then it is possible to obtain the coordinates of the input point of each sensor 6 from the distance 1 between each sensor 6 and the pen 5 and by means of a 3-square theorem.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate input device, and more particularly to detecting the vibration input from a vibrating pen by a vibration sensor provided on the vibration transmitting plate to detect the coordinates of the vibrating pen on the vibration transmitting plate. The present invention relates to a coordinate input device.

[0002]

2. Description of the Related 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. In this type of device, the input image information including characters and figures is displayed and output on a display device such as a CRT display or a recording device such as a printer.

Of these coordinate input devices, the following various methods are known as coordinate detection methods for tablet type coordinate input devices.

(1) A system which is composed of a resistance film and a sheet material arranged to face each other, and detects the coordinate value of the pressed point by a change in the resistance value thereof.

(2) A method of detecting a coordinate position based on electromagnetic or electrostatic induction of a conductive sheet or the like arranged opposite to each other.

(3) A method of detecting the coordinate position of the input pen based on ultrasonic vibration transmitted from the input pen to the tablet.

[0007]

However, the conventional coordinate input device adopting the above-mentioned method has the following drawbacks. That is, in the above-mentioned type (1) using a resistance film, the uniformity of the resistor directly influences the accuracy of the figure input, and therefore a resistor having excellent uniformity is required, and therefore a device requiring particularly high precision. Will be very expensive.

Further, since two resistance films for the X coordinate and the Y coordinate are required, the transparency of the coordinate input surface is lowered. For this reason, there is also a drawback that the original becomes difficult to see when it is used by overlapping it with the original.

Next, in the type (2) utilizing electromagnetic induction, since the electric wires are arranged in a matrix, the coordinate input surface is not transparent, and it can be used by overlapping it on a document or a display. Is inappropriate. Further, the coordinate detection accuracy of the device according to this method directly depends on the positions of the electric wires arranged in a matrix, that is, the processing accuracy, so that a highly accurate input device becomes very expensive.

Compared to these methods, the ultrasonic method (3) is a method for detecting the delay time of a wave propagating on the tablet which is the input surface and calculating the position coordinates.
Since no work such as a matrix-shaped electric wire is applied on the tablet, it is possible to provide an inexpensive device.

Moreover, if a transparent plate glass is used for the tablet, a coordinate input device having a higher degree of transparency than other methods can be constructed.

However, in the conventional ultrasonic coordinate input device, the position coordinate is calculated by detecting the arrival delay time in which the vibration generated by the input pen propagates from the input point to the sensor on the tablet. First, it is necessary to know the reference time, that is, the time when the vibration occurs from the input pen.

Therefore, it is necessary to constantly input the time information when the vibration occurs in the input pen to the circuit for detecting the arrival delay time, and the input pen generating the vibration needs to be connected to the main body by a cable or the like. It was Therefore, when inputting a character, a figure, etc. using this coordinate input device, the operability becomes poor.

When the signal is transmitted by radio waves or the like, it is necessary to incorporate a transmitter or the like in the pen, and it is difficult to realize the same shape, weight and operability as those of ordinary writing instruments. It was

An object of the present invention is to solve the above-mentioned problems, and in a coordinate input device utilizing ultrasonic vibration, by eliminating the need for exchanging signals between the vibration input pen and the coordinate position detecting side, An object of the present invention is to provide a low-cost coordinate input device while improving the operability by eliminating the connecting cable between the pen and the coordinate position detecting side.

[0016]

In order to solve the above-mentioned problems, in the present invention, the vibration transmitted from the vibrating pen is detected by detecting the vibration input from the vibrating pen by a vibration sensor provided on the vibration transmitting plate. In a coordinate input device for detecting coordinates on a plate, means for extracting a plurality of signal components having different transmission speeds from detection signal waveforms obtained by detecting vibrations transmitted on the vibration transmission plate by a sensor. From the vibrating pen from the vibrating pen from the vibrating pen from the time measuring means for obtaining the transmission time difference of each signal component obtained by the extracting means, the transmission speed of the plurality of signal components on the vibration transmission plate, and the time measuring means. A structure having means for detecting the distance to the vibration sensor and calculating the position of the vibrating pen based on the detected distance is adopted.

[0017]

According to the above construction, since the vibration transmission distance is detected based on the transmission time difference of the different signal components on the vibration transmission plate, the transmission and reception of the signal for synchronizing the vibration input timing of the input pen and the detection circuit section. Eliminates the need for

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the drawings.

FIG. 1 shows the structure of an information input / output device adopting the present invention.

The information input device of FIG. 1 causes the input tablet consisting of the vibration transmitting plate 8 to input coordinates by the vibrating pen 3, and the display 11 consisting of a CRT arranged on the input tablet in accordance with the input coordinate information. The input image is displayed on.

In the figure, reference numeral 8 is a vibration transmitting plate made of a glass plate or the like, and transmits the vibration transmitted from the vibrating pen 3 to three vibration sensors 6 provided at its corners. In the present embodiment, the coordinates of the vibration pen 3 on the transmission plate 8 are detected by processing the detection signal waveform 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 at the peripheral portion and returning toward the central portion, the vibration transmitting plate 8 has an antireflection material 7 whose peripheral portion is made of silicon rubber or the like. Supported by.

The vibration transmission plate 8 is arranged on a CRT (or a liquid crystal display or the like) and a display device 11 capable of dot display, and is adapted to perform dot display 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 as if it were. Appears after the trace of the vibrating pen as if you were writing on paper.

Further, according to such a configuration, the display 11
Alternatively, an input method may be used in which a menu is displayed and the menu item is selected by the vibrating pen, or a prompt is displayed to bring the vibrating pen 3 into contact with a predetermined position. The vibrating pen 3 for transmitting ultrasonic vibrations to the vibration transmitting plate 8 includes a vibrator 4 having a piezoelectric element inside.
The ultrasonic vibration generated by the vibrator 4 is transmitted to the vibration transmission plate 8 via the 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 composed of a battery, etc. Do not give or receive. The electric drive signal generated by the drive circuit 2 is converted into mechanical ultrasonic vibration by the vibrator 4 and transmitted to the vibration transmission plate 8 via the horn unit 5.

Further, by setting the drive frequency of the vibrator 4 to be the resonance frequency of the vibrator 4, it is possible to achieve energy-efficient electricity-
Machine conversion is possible. 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 signals of each of the three vibration sensors 6 are input to the waveform detection circuit 9 and converted into processable detection signals. The arithmetic control circuit 1 detects the coordinate position of the vibration pen 3 on the vibration transmission plate 8 based on the result processed by the waveform detection circuit 9. The detected coordinate information of the vibrating pen 3 is processed in the arithmetic and control circuit 1 according to the output system of the display 11.

That is, the arithmetic control circuit 1 uses the video signal processing device 10 to display the display ll based on the input coordinate information.
Control the output behavior of.

FIG. 2 shows a vibrator driving waveform for driving the vibrator 4 in the vibrating pen 3. As illustrated, the vibrator drive circuit 2 inputs a rectangular wave pulse train of a predetermined length to the vibrator 4 at predetermined intervals, and the vibrator 4 converts the rectangular wave pulse train into mechanical energy. This vibration is transmitted as elastic wave vibration on the vibration transmission plate 8 and detected by the vibration sensor 6.

In this way, the electric energy input to the vibrator 4 is converted into mechanical energy by the vibrator 4 and again converted into electric energy by the vibration sensor 6 via the vibration transmission plate 8 and output. ..

After the electro-mechanical conversion as described above, the mechano-electrically converted signal, that is, the signal detected by the sensor 6 is a spectrum of a single frequency as shown in FIG. Does not mean

This is because the mechanical response of the vibrating pen including the vibrator 4 and the horn portion 5 does not have a single frequency with respect to the electric drive frequency input to the vibrator 4, and various vibrations are generated. This is because the mode responds. Further, by loading the horn portion 5 and the like on the vibrator 4, mechanical energy having a wide band which is damped as a whole is output from the tip of the vibrating pen 4. Therefore, the electric signal output from the sensor 6 is detected as a composite wave in which various frequency components are mixed.

FIG. 4 shows general properties of elastic waves (plate waves) propagating on the plate. Plate wave phase velocity Vp,
It is well known that the group velocity Vg and the group velocity Vg depend on the product of the plate thickness d and the wave frequency f. As described above, the plate wave propagating on the vibration transmission plate 8 is a signal having a wide frequency band because it is damped with respect to the electric drive signal.

Therefore, the signal waveform detected by the sensor 6 is
Comparing it on the time axis, the leading part of the signal waveform is composed of a high-frequency wave having a fast propagation speed, and a plate wave having a low frequency gradually reaches the sensor 6 as time passes. It is electrically converted, and superposed on the high-frequency wave that has reached earlier and is output.

In FIG. 5, the same electric output signal output from the sensor 6 is processed through a bandpass filter having a bandwidth of 40 KHz and different center frequencies, and the distance between the vibrating pen 4 and the sensor 6 and the arrival delay of the wave are processed. Group velocity V due to time
These are the results of obtaining g. It can be seen that when the center frequency of the bandpass filter is high, the group velocity Vg is high, and when the center frequency of the bandpass filter is low, the group velocity Vg is also low.

Therefore, even if the signals output from the sensor 6 are the same, by processing the signals with a bandpass filter having a certain center frequency set, a plate wave having a specific speed corresponding to the center frequency is detected. It becomes possible to do. Now, in the embodiment of the present invention, this coordinate input device uses a first band-pass filter and a second band-pass filter whose center frequency is lower than that of the first band-pass filter to output the signal output from the sensor 6. To process.

Here, the velocity of the wave calculated by the signal waveform processed by the first bandpass filter is V1.
And the velocity of the wave calculated by the signal waveform processed by the second bandpass filter is V2. Further, the time until the plate wave reaches from the vibrating pen 3 to any of the vibration sensors 6 and is processed and detected is t1, respectively.
If t2 and the distance between the vibration pen 3 and its vibration sensor 6 are ι, then Δt = t1-t2 (1) ι = V1 · t1 = V2 · t2 = V2 · (t1 + Δt) (2) Therefore, (V1−V2) · t1 = V2 · Δt That is, t1 = V2 / (V1−V2) · Δt (3) This equation (3) is the arrival delay time processed by the first bandpass filter and the If the difference between the arrival delay times processed by the two band pass filters and the speeds V1 and V2 calculated by the detection signal waveforms processed by the first and second band pass filters are measured in advance, As described above, it is not necessary to know the vibration input timing of the vibration pen 3. That is, time t
Even if 1 is not measured, the distance 1 can be calculated by measuring the arrival time difference Δt between two waves having different velocities. Therefore, there is no need to synchronize the vibrating pen that generates vibration with the detection circuit, and the vibrating pen can be made cordless, which is an excellent effect.

From the above, the signal waveform detection circuit 9 may be constructed as shown in FIG. 8 (here, only one channel is shown among the circuits for three vibration sensors 6 which are similarly constructed. ). That is, the signal output from the vibration sensor 6 and amplified by the preamplifier 91 is input to the signal processing circuit 94 via the first bandpass filter 92 serving as a specific frequency extraction circuit, and the signal processing circuit 94 outputs the signal based on a detection reference described later. The arrival delay timing of the wave is detected, and the counter 96 is started. At the same time, the center delay frequency is input to the signal processing circuit 95 via the second bandpass filter 93 as a specific frequency extraction circuit lower than the first bandpass filter 92, and the arrival delay timing is detected in the same manner.
At that timing, the counter 96 is stopped and the difference Δt between the arrival times of the two waves is measured.

The signal processing circuits 94 and 95 are configured as envelope peak detecting circuits for detecting the peak of the envelope, as will be apparent from the following operation.

FIG. 6 shows a time chart of the signal processing performed by the signal detection circuit 9.

In the figure, reference numeral 41 is a drive waveform for driving the vibrator in the vibrating pen, reference numeral 42 is a detection signal waveform when the vibration transmitted through the vibration transmitting plate is detected by the vibration sensor 6, and reference numerals 42A and 42B are respectively. The signal waveforms are respectively processed by the first bandpass filter 92 and the second bandpass filter 93.

The signal processing thereafter is performed by the signal processing circuit 9
4, 95.

First, reference numerals 43A and 43B are envelopes of the detection signal waveforms that have passed through the bandpass filters 92 and 93, and in order to determine the delay time of each wave, the envelopes of the detection signal waveforms are first. From the differential waveform 44A,
44B is obtained, and zero cross signals 45A and 45B are further obtained.
(Corresponding to the peak of the envelope) is detected.

Then, the first bandpass filter 92 starts a counter 96 for measuring the delay time difference from the processed detection signal, and the second bandpass filter 9 is started.
The counter 96 is stopped based on the detection signal processed in step 3, and the measurement of the delay time difference Δt is completed.

The signal waveform detection circuit 9 outputs the above Δt to the arithmetic control circuit 1. The distance ι between the input pen and the sensor can be obtained from the equations (2) and (3) from the difference Δt in delay time. FIG. 7 is an explanatory diagram for obtaining the coordinates (x, y) of the position P of the vibrating pen 3 using the distance between the input pen and the sensor.

In the case of this embodiment, the vibration transmitting plate 8 has three corners.
The two vibration sensors 6 are arranged at positions S1 to S3, and the linear distances from the input point to the vibration sensor 6 are i1, ι
If 2,3 is calculated based on the equations (2) and (3), the coordinates (x, y) can be obtained from the Pythagorean theorem as in the following equation.

X = X / 2 + (ι1 + ι2) (ι1-ι2) / 2X (4) y = Y / 2 + (ι1 + ι3) (ι1-ι3) / 2Y (5) Here, X and Y are S2 and S3. Is the distance along the X and Y axes between the vibration sensor 6 at the position of and the sensor 6 at the origin (position S1). In this way, the position coordinates of the vibration pen 3 can be detected, and the input coordinates can be sequentially detected in real time by repeating the above processing.

As described above, according to the present embodiment, the coordinate calculation can be performed without the need for the detecting device side to know the input timing of the vibrating pen. Therefore, the timing information can be obtained between the vibrating pen and the device main body side having the vibration transmitting plate. It is not necessary to send and receive, and the vibration pen can be made wireless, and the operability at the time of input can be significantly improved. For the detection control system, a simple and inexpensive circuit using a bandpass filter can be used, and since members such as cables are not required, the cost of the device can be reduced.

In the above description, the transparent vibration transmitting plate is used to explain the apparatus used in combination with the display or the original. However, when it is not necessary to use the display or the original in addition to the original, an opaque metal or the like is used. The material of may be used.

[0051]

As is apparent from the above, according to the present invention, the vibration input from the vibrating pen is detected by the vibration sensor provided on the vibration transmitting plate, and the coordinates of the vibrating pen on the vibration transmitting plate are detected. In the coordinate input device for detecting a plurality of signal components having different transmission speeds from the detection signal waveform obtained by detecting the vibration transmitted on the vibration transmission plate by the sensor, and the extracting means. A time measuring means for obtaining a difference in transmission time of each signal component obtained by, a transmission speed of the plurality of signal components on the vibration transmission plate, and a distance from the vibrating pen to the vibration sensor from a time measured by the time measuring means. Of the vibration pen and the position of the vibrating pen is calculated based on the detected distance, vibration transmission is performed based on the difference in transmission time of different signal components on the vibration transmission plate. Since the separation is detected, there is no need to send and receive a signal that synchronizes the vibration input timing of the input pen and the detection circuit section, and there is no signal exchange between the vibration pen and the device main body including the vibration transmission plate, making the vibration pen wireless. This makes it possible to provide a simple, inexpensive, and excellent coordinate input device that can significantly improve the operability when inputting coordinates.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a structure of a coordinate input device according to the present invention.

FIG. 2 is an explanatory diagram showing a vibrator driving waveform and a detection signal waveform of the device of FIG.

3 is an explanatory diagram showing a detection signal spectrum of the device of FIG. 1. FIG.

FIG. 4 is a diagram showing the general properties of plate waves.

FIG. 5 is a diagram showing a relationship between a center frequency of a bandpass filter and a plate wave group velocity.

6 is a timing chart showing vibration detection of the device of FIG.

FIG. 7 is an explanatory diagram showing a vibration sensor arrangement.

FIG. 8 is an explanatory diagram showing a configuration of a signal waveform detection circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Arithmetic control circuit 3 Vibration pen 4 Oscillator B Oscillator drive power source 6 Vibration sensor 8 Vibration transmission plate 9 Signal waveform detection circuit 10 Video signal processing device 11 Display 91 Preamplifier 92, 93 Bandpass filter 94, 95 Signal processing Circuit 96 counter

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yuichiro Yoshimura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Ryozo Yanagisawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Co., Ltd. (72) Inventor Shinnosuke Taniishi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (1)

[Claims] 1. A coordinate input device for detecting a vibration input from a vibrating pen by a vibration sensor provided on a vibration transmitting plate to detect coordinates of the vibrating pen on the vibration transmitting plate. Of the detected signal waveform obtained by detecting the transmitted vibration with a sensor, a means for extracting a plurality of signal components having different transmission speeds, and a timing for obtaining a transmission time difference of each signal component obtained by the extracting means. Means, the transmission speed of the plurality of signal components on the vibration transmission plate, and the distance from the vibrating pen to the vibration sensor from the time measured by the time measuring means, and based on this detection distance, A coordinate input device comprising means for calculating a position.