JPH0922326A - Coordinates input device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact coordinates input device. SOLUTION: Near the corners on a vibration propagating object 8, vibration sensors 6a and 6b having directivity are arranged along the sides. When vibrations are impressed by a vibrating pen 3, the sensors detect those vibrations, but since the sensors have directivity, the output signals of the sensors change their values corresponding to the direction of an input point. Since two sensors in different directions are combined, their output ratio corresponds to the direction of the input point. Besides, the distance to the input point is found from the delay time from the input of vibrations to the detection and the propagation speed of vibrations as well and that distance and the direction can be outputted as the coordinate values of the input point.

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 a device for detecting elastic wave vibration input from a vibrating pen by a sensor provided on a vibration transmitting plate and detecting coordinates of a vibration input point by the vibrating pen. It is a thing.

[0002]

2. Description of the Related Art A coordinate input device using ultrasonic waves is disclosed in Japanese Patent Publication No.
As proposed in 62771, etc., a plurality of vibration detection means (sensors) are installed on the tablet which is the input surface, the input vibration is detected by the vibration input means, and the time required for its propagation is In this method, the distance between the sensor and the vibration input means is calculated from the propagation velocity, and the input position coordinates are detected. Therefore, 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, it is possible to construct a coordinate input device having higher transparency than other methods.

[0003]

However, in the conventional coordinate calculation, as shown in FIG. 7, the sensors (7a to 7d) installed at a plurality of places measure the propagation delay time and calculate the distance from the velocity. Then, the coordinates were geometrically calculated based on the distance between the sensors. For example, the x coordinate is calculated as x = (da ^ 2-db ^ 2 / 2X) (however, in x ^ y, y represents an index).

Therefore, a place for installing a plurality of sensors around the propagating body is required, and an area for canceling the end face reflection is required. Therefore, a certain amount of space is required in addition to the input area. Therefore, there is a problem that it is difficult to use for a portable device or the like.

The present invention has been made in view of the above conventional example, and an object of the present invention is to provide a compact coordinate input device which can effectively use the coordinate input surface. Another object of the present invention is to provide a coordinate input device that is compact and inexpensive.

[0006]

In order to solve the above-mentioned problems, the coordinate input device of the present invention has the following structure. That is, the direction of the vibration input point is determined from the propagation member that propagates the input vibration, the vibration detection unit that has the directivity that detects the vibration that propagates to the propagation member, and the vibration that is detected by the vibration detection unit. Direction derivation means for deriving, distance deriving means for measuring the propagation time of the vibration detected by the vibration detection means and deriving the distance to the vibration input point, and vibration input based on the direction and distance of the vibration input point And output means for outputting the point coordinates.

Alternatively, a propagating member for propagating the inputted vibration, and a vibration detecting means having directivity for detecting the vibration propagating to the propagating member at at least two detection points on the vibration propagating body, Direction derivation means for deriving the direction of the vibration input point at each of the detection points from the vibration detected by the vibration detection means, and output means for outputting the vibration input point coordinates based on the direction of the vibration input point at each of the detection points. With.

With the above configuration, the vibration propagating from the vibration input point is detected, the direction and distance to the vibration input point are derived, and the derived values are output as the coordinate values to be obtained.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the structure of a coordinate input device according to this embodiment. In the figure, reference numeral 1 denotes an arithmetic control circuit for controlling the entire apparatus and calculating a coordinate position.
The vibrator driving circuit 2 is arranged in the vibrating pen 3, and the vibrator 4
The pen tip is vibrated by vibrating. Vibration transmitter 8
Is made of a transparent material such as acrylic or glass plate. The input of coordinates by the vibration pen 3 is performed by touching the vibration transmission plate 8. A vibration isolator 7 is provided on the outer periphery of the vibration transmission plate 8 to prevent (reduce) the reflected vibration from returning to the central portion. In the present embodiment, mechanical vibration is converted into an electrical signal at the upper left portion. The vibration sensors 6a-6b are fixed.

The detection circuit 5 processes the vibration detected by the vibration sensors 6a-6b and outputs the result to the arithmetic control circuit 1.
The vibrator 4 built in the vibrating pen 3 is the vibrator driving circuit 2
Driven by The drive signal for the vibrator 4 is supplied as a low-level pulse signal from the arithmetic control circuit 1 and amplified by the vibrator drive circuit 2 with a predetermined gain, and then the vibrator 4
Is 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 pen tip.

By making the vibration frequency of the vibrator 4 a resonance frequency including the pen tip, efficient vibration conversion is possible.

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 and obstacles on the surface of the vibration transmitting plate as compared to surface waves. .

In the above-mentioned configuration, the arithmetic control circuit 1 outputs a signal for driving the vibrator 4 in the vibrator driving circuit 2 and the vibrating pen 3 at every predetermined cycle (for example, every 10 ms), and the internal timer ( (Consisting of counters) to start timing. Then, the vibration generated by the vibrating pen 3 arrives with a delay depending on the distance to the vibration sensors 6a to 6b.

The vibration sensors 6a-6b have directivity with respect to the angle of incidence on each of them. In the figure, the broken line indicates the directivity direction. The length of each sensor in the major axis direction is approximately equal to the half wavelength of the propagating vibration, and the output is configured to be the maximum with respect to the vibration input from this axial direction. As shown in FIG. 2, these vibration sensors have a directivity direction of 9
When they are arranged so as to form 0 degree, the respective sensor outputs have different magnitudes depending on the incident angle.

In FIG. 2, when vibration enters from the direction of arrow 1, the output of the sensor 6a is large and the output of the sensor 6b is smaller than that due to the directivity of each sensor. On the contrary, when the light enters from the direction of arrow 3, the output of the sensor 6b becomes larger. With respect to the vibration incident from the direction of the arrow 2 which is the center of each, the outputs of both sensors have almost the same value.

The vibration waveform detection circuit 5 includes vibration sensors 6a to 6a.
The signal from 6b is detected, and a signal indicating the incident angle to each vibration sensor and the vibration arrival timing is generated by the waveform detection processing described later.
The coordinate position of the vibrating pen is calculated from the vibration arrival time. Further, the arithmetic control circuit 1 outputs coordinates of the calculated position information of the vibrating pen 3 to an external device (host device or the like) by serial or parallel communication (not shown).

FIG. 3 is a block diagram showing a schematic configuration of the detection circuit 5 of the embodiment, and each component and its operation outline will be described below.

In the figure, amplifier circuits 31a and 31b amplify the sensor output with a predetermined gain. The amplified sensor output is envelope-detected by envelope detection circuits 32a and 32b formed by an absolute value circuit, a low-pass filter, or the like. The detected envelope is peak-held by the peak-hold circuits 33a and 33b. The peak hold circuit holds the signal until the reset signal for the next detection is sent from the arithmetic control circuit 1 or until the A / D conversion in the subsequent stage is completed. The held voltage values from the two sensors are input to the voltage ratio output circuit 34 configured by a known division circuit or the like. The voltage ratio output circuit 34 outputs the ratio of each output voltage. Generally, in a coordinate input circuit or the like using elastic waves, a considerable level fluctuation occurs due to the writing pressure at the time of input. Therefore, the angle cannot be specified only from the voltage value of each sensor output.
Therefore, in the present embodiment, the output voltage ratio of the two sensor outputs is detected as the angle information. The detected voltage ratio is converted into a digital value by the A / D converter 35 and input to the microcomputer in the arithmetic control circuit 1. The microcomputer calculates the incident angle of vibration based on this value. The calculation of the incident angle is
You may refer to the table created for each angle in advance, or you may normalize the specific output for each angle to a numerical value from maximum to minimum and represent it with a corresponding calculated value. Various calculation methods may be selected as

For example, in FIG. 2, the sensors 6a, 6
Output graphs (a), (b), and (c) of b are shown. This corresponds to each of the incident directions 1, 2, 3 of the vibration. If the output ratio of the graph (a) is obtained, it is determined that the vibration is incident in the direction of the arrow 1, and if the output ratio of the graph (b) is obtained, it is the vibration that is incident from the direction of the arrow 2. . In this way, the graph of the output ratio is converted into a numerical value, and a table in which the graph is associated with the incident angle may be created in advance.

Further, the voltage ratio output circuit 34 is also configured to use a divider in this embodiment, but without using this, for example, in FIG. 3, for each detection system for each of the sensors 6a and 6b, The same configuration can be achieved by providing an A / D converter.

In the present embodiment, a method of calculating coordinates using the detected angle and the propagation delay time will be described.

<Description of Vibration Propagation Time Detection (FIGS. 4 and 5)
> Hereinafter, the principle of measuring the vibration transmission time to the vibration sensor 3 will be described.

FIG. 4 is a diagram for explaining a detection waveform input to the vibration waveform detection circuit 5 and a vibration transmission time measuring process based on the detection waveform. Hereinafter, a case where the vibration sensor 6a calculates the distance will be described. The distance calculation may be performed by switching such that one having a higher signal level is used, or the average of both may be used. In such a case, the same applies to the detection of 6b.

The measurement of the vibration transmission time to the vibration sensor 6a starts at the same time when the start signal is output to the vibrator drive circuit 2. These measurements can be easily realized by a counter composed of so-called digital circuits. A drive signal 41 is applied from the oscillator drive circuit 2 to the oscillator 4. The ultrasonic vibration transmitted from the vibration pen 3 to the vibration transmission plate 8 by the drive signal 41 progresses for a time tg corresponding to the distance to the vibration sensor 6a, and then is detected by the vibration sensor 6a. The signal 42 shown is the vibration sensor 6a.
Shows the signal waveform detected by.

Since the vibration used in this embodiment is a plate wave, the relationship between the envelope 421 and the phase 422 of the detected waveform with respect to the propagation distance in the vibration transmission plate 8 is the transmission distance during the vibration transmission. Change according to. Here, the group velocity of the envelope 421 traveling is Vg, and the phase velocity of the phase 422 is Vp. This group velocity Vg and phase velocity V
The distance between the vibration pen 3 and the vibration sensor 6a can be detected from p.

First, focusing only on the envelope 421, its speed is Vg, and a specific point on the waveform, for example, an inflection point, is determined by the second-order differential signal 43 of the envelope 421.
When it is detected by the zero cross point of, the distance between the vibration pen 3 and the vibration sensor 6a is given by d = Vg · tg (1) with the vibration transmission time to the inflection point as tg of 49 in the figure. Of course, it is possible to determine the coordinates using only this distance. However, in order to determine the coordinates with higher accuracy, processing based on the detection of the phase signal is performed.

Assuming that the time from a particular detection point of the phase waveform signal 422, for example, vibration application to the zero cross point after reaching a certain predetermined signal level 441 is tp47, the distance between the vibration sensor and the vibration pen is d = N · λp + Vp · tp (2) The tp 47 generates a window signal 44 having a predetermined width with respect to the signal 45 indicating that the predetermined signal level is exceeded, and outputs the phase signal 422 to the band pass filter 511 described later.
It is obtained by comparing with the window signal 44 obtained by inputting into the.
Here, λp is the wavelength of the elastic wave, and n is an integer.

From the above equations (1) and (2), the above 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, then n can be determined if there is a variation such as tg within ± 1/2 wavelength. By substituting n obtained as described above into the equation (2), the distance between the vibration pen 3 and the vibration sensor 6a can be accurately measured. The signals 43 and 45 are generated by the vibration waveform detection circuit 5 for measuring the two vibration transmission times tg and tp described above, and the vibration waveform detection circuit 5 is configured as shown in FIG.

FIG. 5 is a block diagram showing the configuration of the vibration waveform detection circuit 5 of the embodiment.

In FIG. 5, the output signal of the vibration sensor 6a is amplified to a predetermined level by the preamplifier circuit 51. The amplified signal is filtered by a band-pass filter 511 to remove extra frequency components from the detection signal. The amplified signal is input to, for example, an envelope detection circuit 52 including an absolute value circuit and a low-pass filter. Only those are retrieved. Also, in this circuit, tg, tp
The window signal used in the detection circuit is also output. The envelope timing is detected by the twice differentiating circuit 53. The peak detection circuit is a signal tg (FIG. 4) which is an envelope delay time detection signal of a predetermined waveform by the tg signal detection circuit 54 composed of a mono-multivibrator.
The signal 43) is formed and input to the arithmetic and control circuit 1.

On the other hand, the tp signal detection circuit 55 outputs the signal 4 based on the window signal detected by the envelope detection circuit 52.
The zero crossing point of the phase signal 47 of 4 is detected, and the phase delay time signal tp is supplied to the arithmetic control circuit 1.
With this signal, the delay time is measured and the distance from the sensor to the vibration input point is calculated.

For the error component and the like within the delay time,
According to a known method such as the description of No. 62771,
It enables accurate distance detection.

Thus, if the distance d to the vibration input point is known, for example, if polar coordinates are output, it is also possible to output the coordinate points together with the angle θ at (θ, d). It is also possible to convert the coordinates into an orthogonal coordinate system and output as (x, y).

[0036]

[Second Embodiment] FIG. 6 is a view showing another embodiment of the present invention, in which three anisotropic sensors are arranged in the central portion instead of the upper corner portion.

In this case, the angle may be calculated from the level ratio of 6A, 6B and 6C.

In FIG. 6, incidence from the back surface of each sensor,
In order to provide a difference with the vibration that is incident from the opening direction, a member 6D (made of resin, rubber material, etc.) having a vibration damping effect is provided in the back direction of the sensor, and the directivity is further emphasized. is there.

In the above description, a prism-shaped sensor has been used for explanation, but of course, any shape such as a circle, an ellipse or any other shape may be used as long as the sensor has directivity.

By controlling the polarization direction, anisotropy can be generated and used.

[0041]

Third Embodiment In the second embodiment, an example has been described in which the coordinates are obtained from the detected angle and the distance obtained from the propagation delay time. Here, an example will be described in which the coordinate calculation is obtained only from the angle without using the delay time.

FIG. 8 shows an example in which a mechanism similar to that of the first embodiment is provided in the upper right corner and angle detection is performed at two locations. If the distance (coordinates) between both sensors is known, both of them are detected. Coordinates are obtained by calculating the points where the angles intersect.

For example, if the distance between the sensors is X and the angles detected by each are θ and φ, then x = X · tanφ / (tan θ + tanφ) y = X / (1 in the coordinate system as shown in FIG. / Tan θ-1 / tan φ).

With this structure, the structure for measuring the propagation delay time is unnecessary, the circuit structure is simplified, and an inexpensive device can be provided.

Further, the cost can be further reduced even if the detection circuit is used for the time division by the left and right sensors.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0047]

As described above, according to the present invention, by using a plurality of sensors having anisotropy with respect to the incident angle and detecting the ratio of outputs, the angle can be detected irrespective of level fluctuations such as writing pressure. Since the number of sensor installation locations can be reduced, it is possible to provide a compact coordinate input device that does not require much invalid area.

If the coordinate calculation is performed only by detecting the angle, the circuit can be simplified and the cost can be reduced.

[0049]

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a coordinate input device.

FIG. 2 is an explanatory diagram of incident angles and levels.

FIG. 3 is a block diagram of a detection circuit.

FIG. 4 is a time chart of signal processing.

FIG. 5 is a block diagram of a delay time detection circuit.

FIG. 6 is a diagram showing another embodiment.

FIG. 7 is an explanatory diagram of conventional coordinate calculation.

FIG. 8 is an explanatory diagram of coordinate calculation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 arithmetic control circuit 2 oscillator drive circuit 3 vibration input pen 4 oscillator 5 detection circuit 6a-6b vibration sensor 7 vibration isolator 8 vibration transmission plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masaki Tokioka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hajime Sato 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Ryozo Yanagisawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (8)

[Claims] 1. A vibration input point that propagates an input vibration, a directional vibration detection unit that detects the vibration that propagates to the propagation member, and a vibration input point based on the vibration detected by the vibration detection unit. Based on the direction and distance of the vibration input point, the direction deriving means for deriving the direction of the And an output unit for outputting the coordinates of the vibration input point. 2. The vibration detecting means includes at least two vibration sensors having directivities arranged so that the respective directing directions form a predetermined angle, and the direction deriving means causes each of the output sensors to vibrate. The coordinate input device according to claim 1, wherein the direction is derived based on the output ratio of the detected. 3. The distance deriving means derives the distance to the vibration input point based on the delay time from the input of the vibration to the detection of the vibration and the propagation speed of the vibration. The coordinate input device according to 1 or 2. 4. A conversion means for converting a polar coordinate system represented by the direction and distance of the vibration input point into a rectangular coordinate system, wherein the output means outputs the coordinates of the vibration input point in the rectangular coordinate system. The coordinate input device according to any one of claims 1 to 3, wherein 5. The vibration propagating body has a rectangular shape, and the vibration detecting means is provided in the vicinity of a corner of the vibration propagating body so as to extend along two sides of a rectangle in which directions of orientation are orthogonal to each other. The coordinate input device according to claim 2, further comprising a sensor. 6. The vibration propagating body has a rectangular shape, and the vibration detecting means is provided near the center of one side of the vibration propagating body.
3. The vibration sensor according to claim 2, wherein the vibration sensors include three vibration sensors arranged so that the directions thereof are different by 90 degrees.
The coordinate input device described in. 7. A propagating member that propagates the input vibration, and a vibration detecting unit having directivity that detects the vibration propagating to the propagating member at at least two detection points on the vibration propagating body, Direction derivation means for deriving the direction of the vibration input point at each of the detection points from the vibration detected by the vibration detection means, and output means for outputting the vibration input point coordinates based on the direction of the vibration input point at each of the detection points And a coordinate input device. 8. The vibration detecting means includes at least two vibration sensors having directivities arranged so that the respective directing directions at respective detection points form a predetermined angle, and the direction deriving means comprises: 8. The coordinate input device according to claim 7, wherein each output sensor derives the direction based on the output ratio of the detected vibration.