JPH1165747A - Coordinate input device and coordinate detection method - Google Patents

Abstract

(57) [Summary] [Problem] To provide a highly accurate coordinate input device capable of correcting an offset shift caused by a temperature change with a simple circuit configuration. A vibration input pen includes a drive circuit for driving a vibrator and a delay circuit. The arithmetic and control circuit 1
A drive signal is supplied to the drive circuit 21 to detect a time required for the vibration input from the vibration input pen 3 input to the vibration transmission plate to reach the vibration detecting means, and based on the detected arrival time, the vibration input pen 3 is used. To obtain the coordinate position indicated by. Further, the arithmetic and control circuit 1 inputs a predetermined signal to the delay circuit 22 and inputs a return signal thereof to measure a delay time of the delay circuit 22, and based on the measured delay time, The arrival time used for coordinate calculation is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a coordinate input device and a coordinate detection method thereof. More specifically, the elastic wave vibration input from the vibration pen or the like is detected by a plurality of sensors provided on the vibration transmission plate, and the coordinates of the vibration input point are determined based on the transmission time of the elastic wave vibration input to the vibration transmission plate. The present invention relates to a coordinate input device to be detected and a coordinate detection method thereof.

[0002]

2. Description of the Related Art As disclosed in Japanese Patent Publication No. 5-62771, a coordinate input device using elastic wave vibration detects a delay time of a wave propagating on a tablet which is an input surface, and detects a position coordinate. Is calculated. Since it is not necessary to apply a matrix wire or the like to the tablet of this kind of coordinate input device, it is possible to provide an inexpensive device. Moreover, if a transparent plate glass is used for the tablet, a coordinate input device having higher transparency than other methods can be configured.

In this type of apparatus, Japanese Patent Laid-Open Publication No.
As disclosed in US Pat. No. 10,300, a delay time may be offset due to an environmental temperature, and an error may occur in coordinate detection. The amount of this offset shift varies mainly depending on the pen temperature. For this reason, JP-A-07-21
In 0300, as a countermeasure, a delay circuit whose delay amount changes with temperature is provided in the vibration input pen. The delay amount with respect to the temperature of the delay circuit is configured to be equal to the offset amount, and the pen drive timing is shifted by the delay amount to offset the offset shift.

[0004]

However, conventionally, a configuration has been adopted in which a pulse for driving a vibrator is oscillated in a pen with a delay with respect to a drive signal timing. This is because when a drive pulse passes through the delay circuit, a regular signal (for example, 500 KHz is 2
Departure) cannot pass. As described above, in the above configuration, since the offset shift mainly depends on the temperature of the pen, it is necessary to provide a delay circuit in the pen and further provide an oscillation circuit and the like in the pen. Therefore, the circuit scale of the pen driving unit increases, and the pen becomes thick and difficult to use.

Further, since the deviation of the oscillation frequency greatly affects the characteristics, strict control is required, and the delay time must be set equal to the offset deviation generated by the pen. There is a problem that mass productivity is poor, such as an adjustment is required and a permissible amount of component variation is narrow.

The present invention has been made in view of the above problems, and has as its object to provide a coordinate input device and a coordinate detection method capable of correcting an offset shift caused by a temperature change with a simple circuit configuration.

[0007]

A coordinate input device according to the present invention for achieving the above object has the following arrangement. That is,
Detecting means for detecting an arrival time until vibration from the vibration input means input to the vibration transmission plate reaches the vibration detecting means; and instructed by the vibration input means based on the arrival time detected by the detecting means. Acquisition means for acquiring the coordinate position, a delay means provided in the vibration input means, the delay amount changing with temperature, and a signal input to the delay means. The system includes a clock unit for measuring a delay time until a corresponding signal arrives, and a correction unit for correcting the arrival time used by the acquisition unit based on a result of the clock by the clock unit.

According to another aspect of the present invention, there is provided a coordinate detecting method for detecting coordinates based on a propagation time of a vibration applied to a vibration transmitting plate.
A detection step of detecting an arrival time until the vibration input from the vibration input unit input to the vibration transmission plate reaches the vibration detection step, and instructing by the vibration input unit based on the arrival time detected by the detection unit. A signal input to a delay means provided in the vibration input means, the delay amount of which varies with temperature, and a signal corresponding to the signal is output from the delay means. And a correction step of correcting the arrival time used in the acquisition step based on the result of the time measurement by the time measurement step.

[0009]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a diagram showing a configuration of a coordinate input device according to the present embodiment. In FIG. 1, reference numeral 1 denotes an arithmetic control circuit for controlling the entire apparatus and calculating a coordinate position.
Reference numeral 3 denotes a vibrating pen, in which a vibrator driving circuit 2,
The vibrator (piezoelectric element such as PZT) 4 is stored. Reference numeral 5 denotes a pen tip of the vibration pen 3. A vibrator driving circuit 2 drives the vibrator 4 by a pen driving signal output from the arithmetic and control circuit 1. The vibration generated by the vibrator 4 is
After passing through the horn, the pen tip 5 is vibrated. 1a is a signal cable for connecting the arithmetic control circuit 1 and the vibration pen 3.

Reference numeral 8 denotes a vibration transmission plate made of a transparent member such as a glass plate. Coordinate input by the vibration pen 3 is performed by touching the vibration transmission plate 8. Actually, the user designates the area within the area indicated by the symbol A (hereinafter referred to as the effective area) indicated by the solid line with the vibration pen 3. 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.
Vibration sensors 6a to 6d for converting mechanical vibration into electric signals
Has been fixed.

Reference numerals 12a to 12d denote amplifiers for amplifying output signals from the respective vibration sensors 6a to 6d. Reference numeral 9 denotes a signal waveform detection circuit which detects the arrival timing of the vibration based on the signal waveform from each of the sensors 6a to 6d amplified by the amplifiers 12a to 12d. Reference numeral 10 denotes a display drive circuit which drives the display 11 in accordance with a display instruction from a host device. 11 is a display,
It is arranged under the vibration transmission plate 8 so as to overlap. In the present embodiment, a liquid crystal display is used as the display 11, but it goes without saying that a display of another type may be used.
Note that the host device controls the display drive circuit 10 to display a point at a position corresponding to the coordinate value output from the arithmetic and control circuit 1, so that an image corresponding to the input locus of the vibration pen is obtained on the display 11. Can be This allows the user to check the input trajectory as if he were writing on paper.

FIG. 2 is a diagram for explaining the configuration of the vibrator driving circuit 2 of the vibrating pen according to the present embodiment. A driving circuit 21 amplifies the pen driving signal and drives the vibrator 4.
Reference numeral 22 denotes a delay circuit. The input pen driving signal is time-delayed in the delay circuit 22 according to the temperature at that time, and is output to the arithmetic and control circuit 1 as a return signal. As shown in FIG. 2, the pen drive signal is input to the drive circuit 21 and the delay circuit 22.

FIG. 3 is a timing chart conceptually showing the timings of the pen drive signal and the return signal. In driving for acquiring coordinates, a pulse train having a driving frequency of 500 [MHz] is supplied as shown in FIG. Since this pulse is generated based on the clock in the arithmetic and control circuit, it can be supplied as a highly accurate signal. Usually, this pulse drives the vibrator 4 in the pen. Also,
3b is a delay time measuring pulse. In this embodiment,
The offset amount is corrected by measuring the difference TDlay between the output time of the pulse 3b and the arrival time of the return signal passing through the delay circuit 22, which will be described later.

In this embodiment, the pen driving signal for detecting the coordinates and the signal for measuring the delay time by the delay circuit 22 are different signals like the pulses 3a and 3b in FIG. This is because the signal for measuring the delay time is set so that the signal can pass through the delay circuit in consideration of the frequency characteristics of the delay circuit. Hereinafter, the pulse 3a is also called a drive signal, and the pulse 3b is also called a delay amount measurement signal. Note that the delay amount measurement signal may be set to a high state until the delayed signal returns in order to eliminate the influence of the delay circuit characteristics.

First, signal processing in a normal coordinate value acquisition operation will be described.

When the drive signal 3a is supplied to the vibration input pen 3, the drive circuit 21 amplifies the drive signal 3a and
And the pen tip 5 vibrates as a result. The vibration applied from the pen tip 5 to the vibration transmission plate 8 propagates through the vibration transmission plate 8 and is detected by the sensors 6a to 6d. The vibrations detected by the sensors 6a to 6d are output from the preamplifiers 12a to 12d.
And is input to the signal waveform detection circuit 9.

The vibration frequency of the vibrator 4 is selected to a value at which a plate wave can be generated on the vibration transmission plate 8.
Therefore, the elastic wave propagating through the vibration transmission plate 8 becomes a plate wave.
The plate wave has an advantage that the surface of the vibration transmission plate is less susceptible to scratches, obstacles, and the like than surface waves.

The arithmetic and control circuit 1 operates at predetermined intervals (for example, 10
Every millisecond), the coordinate acquisition operation is repeated to output the coordinates. In the coordinate acquisition operation, a plurality of sensors 6a to 6d are sequentially selected, and each sensor detects an arrival delay time of an elastic wave. The arrival delay time includes a group delay time tg based on the group velocity of the plate wave and a phase delay time tp based on the phase velocity.
The distance between the input pen and each sensor is calculated based on both delay times.

FIG. 4 is a block diagram showing the configuration of the signal waveform detection circuit of the present embodiment. FIG. 5 is a diagram showing waveforms at various parts in the signal detection circuit. Hereinafter, the propagation delay time measurement according to the present embodiment will be described with reference to FIGS.

First, the arithmetic and control circuit 1 outputs a sensor select signal to the sensor selection circuit 31 to select one sensor. Next, the arithmetic and control circuit 1 outputs a drive signal (FIG. 5).
And the internal timer (counters 102a and 102b in FIG. 6 to be described later).
) Is started. Hereinafter, a case where the vibration sensor 6a is selected will be described as an example.

First, an outline of detection of a distance from a vibration input point to a vibration sensor according to the present embodiment will be described. The ultrasonic vibration transmitted from the vibration pen 3 to the vibration transmission plate 8 travels for a time tg corresponding to the distance to the vibration sensor 6a, and is detected by the vibration sensor 6a. A signal indicated by reference numeral 42 in FIG. 5 indicates a signal waveform detected by the vibration sensor 6a. 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 depends on the transmission distance during the vibration transmission. Change. The distance between the vibration pen 3 and the vibration sensor 6a can be detected from the group velocity Vg and the phase velocity Vp. Hereinafter, an outline of the distance calculation will be described.

First, focusing on the envelope 421,
The traveling speed is the group velocity Vg, and if a certain point on the waveform (in this example, an inflection point is used and details will be described later) is detected, the distance between the vibration pen 3 and the vibration sensor 6a is determined. d is given by d = Vg · tg (1) where tg is the vibration transmission time.

If the time until a specific point of the phase waveform signal 422 (in this example, a predetermined zero-cross point is detected and details thereof will be described later) is tp, the distance between the vibration sensor and the vibration pen is , D = n · λp + Vp · tp (2) 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 represented 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. The distance between the vibration pen 3 and the vibration sensor 6a can be accurately measured by substituting n obtained as described above into the expression (2).

The configuration of the present embodiment for realizing the above distance measurement will be described in more detail as follows. In FIG. 4, the output signal of the vibration sensor 6a is amplified to a predetermined level by the preamplifier circuit 12a. The amplified signal (42 in FIG. 5) is selected by the sensor selection circuit 31, and is input to the absolute value circuit 32 and the bandpass filter 37. The signal input to the absolute value circuit 32 is input to an envelope detection circuit 33 composed of a low-pass filter or the like, and only the envelope of the detection signal is extracted (43 in FIG. 5).

The window signal generation circuit 35 compares the envelope signal 43 with the threshold value Vth, and detects the detection window signal t having a predetermined time width from the time when the envelope signal 43 exceeds the threshold value Vth.
w (46 in FIG. 5) is output. On the other hand, the second differentiation circuit 34
Obtains a twice differentiated signal (44 in FIG. 5) by differentiating the input envelope signal 43 twice. The tg signal detection circuit 54 constituted by a comparator compares the twice differentiated signal 44 with the window signal tw, detects the first zero cross point, and forms a tg signal (48 in FIG. 5). The tg signal 48 thus obtained is input to the waveform shaping circuit 39.

On the other hand, the signal (45 in FIG. 5) input to the band-pass filter 37 is input to a tp signal detection circuit constituted by a zero cross comparator using the window signal tw as an enable signal. The tp signal detection circuit generates a signal that is turned on while the level is higher than the window signal tw, and inputs the signal to the waveform shaping circuit 39 as a tp signal (47 in FIG. 5).

In the waveform shaping circuit 39, from the pen drive signal and the tg and tp signals, a process from pen drive to vibration detection is performed.
Both the delay time due to the group velocity and the phase velocity (Tg, Tg
A pulse signal having a time width of p) is generated and output to the arithmetic and control circuit 1. The arithmetic and control circuit 1 measures the time width of the pulse signal using an internal counter, and obtains each propagation delay time. Note that the illustrated DataSet signal is a CP
U is used to detect that a signal has been detected. By detecting this signal, the next delay time measurement is:
Move on to calculation of distance, coordinates, etc.

The delay times Tg and Tp obtained here include a fixed delay time of the group and the phase when passing through the pen tip, the circuit and the like. Therefore, this fixed amount is measured in advance and stored as Tgf and Tpf. And
From the delay times Tg and Tp measured as described above,
Tgf and Tpf are subtracted, and the above equation (2) is used.
The distance is calculated by (3). The same operation is performed for other sensors to calculate the distance from the vibration pen to each sensor.

The propagation delay times Tg and Tp obtained as described above include an offset due to the environmental temperature, as described in the conventional example. That is, T
gf and Tpf include an offset due to the environmental temperature. In order to remove the offset, in the present embodiment, a pulse as shown in FIG. 3B is generated, and the delay time due to the temperature is measured to perform the correction. For correction, first, a reference delay time TDadj of the delay circuit 22 at a certain reference temperature is measured and stored. Then, when the device is used, the delay time TDlay by the delay circuit 22 is measured, and Tgf, Tgf are calculated based on the relative change amount between the reference delay time TDadj and the delay time TDlay.
pf is corrected. It should be noted that the reference temperature is not determined to be a specific temperature, and may be within the operating temperature range of the apparatus.
The temperature needs to be the same as that for obtaining the above Tgf and Tpf. Therefore, it is desirable to perform the measurement at the same time when the fixed delay amounts Tgf and Tpf are measured.

As the reference delay time, the control circuit 1 generates the signal 3b for measuring both delays shown in FIG. 2 and starts timing. The reference delay time TDadj from the signal output to the detection through the delay circuit again is measured. Then, it is stored in a nonvolatile memory or the like.

The temperature delay time TDlay is measured by a similar pulse output during normal operation. Correction amount TDoffse
t is given by TDoffset = (TDadj−TDlay) × Coef (4)

Since TDadj is a delay time at the reference temperature, this difference is a delay amount of the temperature difference from the reference setting. Coef is a coefficient, which is calculated from the ratio of the delay amount to the temperature change of the temperature delay circuit and the offset change amount. For example, the offset amount of Tg and Tp is ± 2.
50 [nsec / 20 ° C.], and the delay amount of the delay circuit 22 is ±
If 1.7 [μsec / 20 ° C.], the coefficient Coef is 250
[Nsec / 20 ° C] /1.7 [μsec / 20 ° C] = 0.147.

The correction amount TDoffset thus obtained is
Is subtracted (added depending on the sign of the delay circuit) from Tg and Tp obtained as described above, and the offset amount can be corrected. In other words, TDoffset is Tgf, Tpf
Tgf and Tpf are corrected by subtraction (or addition), and the delay time is corrected by using the corrected Tgf and Tpf, thereby eliminating the delay time error caused by the temperature difference.

The above processing and the configuration for realizing it will be further described. FIG. 6 is a block diagram showing a configuration of the arithmetic and control circuit 1 according to the present embodiment. Reference numeral 101 denotes a microcomputer, which includes a CPU 101a, an EEPROM 10
1b, a RAM 101c, and a ROM 101d. CP
U101a implements various controls including the above-described coordinate detection and delay time correction according to a control program stored in the ROM 101d. Also, in the EEPROM 101b,
Reference delay time TDadj, coefficient Coef, fixed delay amount Tgf,
Tpf is stored. Also, the RAM 101c is a CPU 1
01a provides a work area for executing various processes.

Reference numerals 102a to 102c denote counters. The counters 102a and 102b start counting by the drive signal 3a, and the tg signal from the signal waveform detection circuit 9 and t
The count value is held by the p signal and output to the microcomputer 101 as timekeeping data. Also, the counter 102c starts posting with the delay amount measurement signal 3b, holds the count value with the return signal passed through the delay circuit 22, and outputs it as timekeeping data. A determination circuit 103 determines the arrival of the tg signal and the tp signal, and notifies the microcomputer 101 of the arrival. 104 is I /
The O port communicates with an external circuit (for example, a host device).

The measurement of the temperature delay amount for correction may be performed at the time of coordinate detection. However, since a temperature change or the like is unlikely to occur suddenly, it is necessary to prevent the sampling rate from lowering. It is preferable to use this value during the up cycle and to use that value in the next pen down cycle.

The procedure of coordinate detection by the arithmetic and control circuit 1 as described above will be further described with reference to the flowchart of FIG. FIG. 7 shows the correction amount TD during use of the coordinate input device.
It is a flowchart showing the processing procedure for obtaining an offset. The following processing is realized by the CPU 101a provided in the arithmetic and control circuit 1 executing a control program stored in the ROM 101d.

The process shown in FIG. 7 is started by turning on the power. First, in step S11, a delay amount measuring signal (delay amount measuring signal 3b (FIG. 3)) is generated.
The delay amount TDlay of the delay circuit 22 is measured. That is,
The counter 102c is activated, and the count value at the time when the return signal corresponding to the delay amount measurement signal is input is used as timekeeping data to acquire TDlay. Next, in step S12, TDoffset is obtained according to the equation (4), and this is stored in the RAM.
The data is stored in a predetermined area 101c.

Next, in step S13, a drive signal is periodically generated to perform a coordinate detection process. If the pen-up state continues for more than the predetermined time, the process returns from step S14 to step S11, executes the above-described processing, and updates TDoffset. Also, when the pen-up operation is detected after the pen-down, the process returns from step S15 to step S11, and updates the correction amount TDoffset.

As described above, when the pen-up state continues for more than a predetermined time, and when the vibration input pen 3 changes from a state in which it comes into contact with the vibration transmission plate 8 (a pen-up operation is detected. ), The correction amount TDoffset is updated. Therefore, it is possible to always maintain the correction amount TDoffset at an appropriate value without substantially affecting the sampling rate of the coordinate detection processing.

Further, in the above description, the temperature delay time is measured by generating the delay amount measuring pulse 3b different from the pen driving signal 3a, but the driving signal 3a itself may be used. .

In the above embodiment, TDadj, Coe
The values of f, Tgf, Tpf, etc. are
Although it is assumed that these values are stored in M101b, these values may be set by the user. In this case, for example, the mode of the coordinate input device may be set to the reference delay time measurement mode, and the processing shown in FIG. 8 may be executed.

FIG. 8 is a flowchart for explaining a procedure for storing correction data including the reference delay time of the delay circuit 22. The following processing is realized by the CPU 101a executing a control program stored in the ROM 101d.

When the operation mode of the coordinate input device is set to the reference delay time measurement mode, in step S21,
The offset amounts of Tg and Tp are measured, and this is determined by Tgf and Tg.
Store as pf. Tgf and Tpf are obtained as follows. First, vibration is applied by the vibration input pen 4 to a position (for example, the center of the area A) at a known distance from each sensor on the vibration transmission plate 8. And each vibration sensor 6 at this time
The offset time T is calculated from the difference between the actual delay time detected by a to 6d and the theoretical delay time obtained from the known distance from the vibration application point and the group velocity Vg and the phase velocity Vp.
gf and Tpf are obtained.

In the following step S22, pulse 3 in FIG.
b until the return signal is detected,
TDad is obtained from the count value of the counter 102c.
j. Further, in step S23, the host device prompts the user to input an offset change amount with respect to the temperature of Tg and Tp and a delay time change amount with respect to the temperature of the delay circuit 22 built in the vibration pen 4, and calculates Coef according to the input values. . Then, in step S24, Tgf, Tpf, TDadj, and Coef obtained in the above processing are converted to EEPRO.
M is stored in a predetermined area. Note that the above coefficients are RA
M, but in this case, the RAM
Can be backed up by batteries etc.
It is desirable to store the coefficient in the predetermined area.

By adopting the above configuration, for example, when the user replaces the vibration input pen, Tg,
Given the amount of change in Tp with respect to temperature and the amount of change in delay time of the delay circuit 22 with respect to temperature, T
gf, Tpf, TDadj, and Coef can be set to appropriate values.

As described above, the distance is calculated from the time data from which the offset has been removed, and accurate distance information (distance da) is calculated.
~ Dd), the coordinates (x, y) of the position P of the vibrating pen 3 can be obtained from the three-square theorem as shown in FIG.

X = (da + db) · (da−db) / 2X (5) or x = (dc + dd) · (dc−dd) / 2X (5 ′) y = (da + dc) · (da−dc) / 2Y (6) or y = (db + dd) · (db-dd) / 2Y (6 ′) where X and Y are the distance between the vibration sensors 6a and 6b and the distance between the vibration sensors 6c and 6d, respectively. is there.

<Other Embodiments> In the above embodiment,
The temperature delay amount may be set arbitrarily. That is, the correction accuracy can be increased by taking a larger change width without matching the actual offset amount. For example, the actual offset has a change of about ± 250 nsec for a change of ± 20 degrees. If the delay amount of the delay circuit is set to this value, it can be used as it is as a correction amount. However, it is more advantageous to make a larger change for ± 20 degrees than to use it as it is in terms of accuracy. Become. FIG. 10 shows an example of the temperature delay circuit. The values of C1, R1, and R2,
It can be changed by selecting the rank (temperature characteristic). In the circuit shown in FIG. 10, since the characteristics of the capacitors are dominant, it is desirable that the rank of the capacitors be as linear as possible in the range of use.

It is obvious that a similar effect can be obtained by using a temperature-sensitive element for the resistor other than the above circuit.

As described in the above embodiment, when setting the reference temperature, the environment temperature at that time is stored in a non-volatile memory or the like so that the user's use environment temperature can be known. it can.

For example, when the device is used outside the specified temperature range of the device, it can be used for adjusting the temperature of the main body or warning the user.

Further, since the drive signal is output and the return thereof is measured, for example, when the pen has come off, the main body can detect that. Therefore, if the delay signal does not return even after the maximum value of the temperature delay time has passed, it is determined that the pen is disconnected, the pen has failed, or the wire has been disconnected.
It is possible to issue a warning to that effect, and it can be used for failure diagnosis and the like.

The present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), but can be applied to a single device (for example, a copier, a facsimile). Device).

An object of the present invention is to provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or apparatus, and to provide a computer (or CPU) of the system or apparatus.
And MPU) read and execute the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, based on the instructions of the program code, It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

As described above, by providing the delay circuit in which the amount of delay changes depending on the temperature in the pen, the offset can be effectively corrected without strictly adjusting the amount of delay to the amount of offset. Further, the correction accuracy can be improved by setting the amount of change in the delay time by the delay circuit to a value larger than the amount of change in the offset. Further, since it is not necessary to provide an oscillation circuit in the pen, the characteristics can be stabilized and the circuit scale can be reduced. In general, when performing temperature compensation, a method is used in which a change in resistance of a thermistor or the like is regarded as a change in voltage, the voltage is changed by an A / D converter, and is taken into a CPU for processing. On the other hand, in the present embodiment, since the amount of time delay is measured (replaced by time change), an A / D converter or the like is unnecessary, and high-speed processing can be performed at low cost. .

[0063]

As described above, according to the present invention, the offset deviation caused by a temperature change can be corrected with a simple circuit configuration, and a highly accurate coordinate input device can be easily provided.

[0064]

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a coordinate input device according to an embodiment.

FIG. 2 shows a vibrator pen vibrator drive circuit 2 according to the present embodiment.
FIG. 3 is a diagram illustrating the configuration of FIG.

FIG. 3 is a timing chart conceptually showing timings of a pen drive signal and a return signal.

FIG. 4 is a block diagram illustrating a configuration of a signal waveform detection circuit according to the present embodiment.

FIG. 5 is a diagram showing waveforms at various parts in the signal detection circuit.

FIG. 6 is a block diagram illustrating a configuration of an arithmetic control circuit 1 according to the present embodiment.

FIG. 7 shows a correction amount TDoffs during use of the coordinate input device.
It is a flowchart showing the processing procedure for obtaining et.

8 is a flowchart illustrating a procedure for storing correction data including a reference delay time of the delay circuit 22. FIG.

FIG. 9 shows coordinates (x, x) of a position P of a vibration pen from distance information.
It is a figure explaining the method of calculating | requiring y).

FIG. 10 is a diagram illustrating an example of a temperature delay circuit according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Operation control circuit 2 Oscillator drive circuit 3 Oscillation input pen 4 Oscillator 5 Pen tip 6a-6d Vibration sensor 7 Anti-vibration material 8 Vibration transmission board 9 Signal waveform detection circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsuyuki Kobayashi, Inventor 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Ryozo Yanagisawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside the corporation

Claims (11)

[Claims] A detecting means for detecting a time required for the vibration inputted from the vibration input means to reach the vibration detecting means, the vibration input means being provided to the vibration transmitting plate; and the vibration based on the arrival time detected by the detecting means. Obtaining means for obtaining a coordinate position instructed by the input means; delay means provided in the vibration input means, the delay amount changing with temperature; and inputting a signal to the delay means, Means for measuring a delay time until a signal corresponding to the signal arrives from the means, and correction means for correcting the arrival time used by the acquisition means based on a result of the time measurement by the time counting means. Coordinate input device. 2. The apparatus according to claim 1, further comprising a conversion unit configured to convert a change amount of the delay time of the delay unit into a change amount of the arrival time to obtain a correction amount, wherein the correction unit calculates the correction amount obtained by the conversion unit. The coordinate input device according to claim 1, wherein the coordinate input device is used to correct an arrival time used by the acquisition unit. 3. A holding means for holding a difference between an arrival time detected by the detecting means at a predetermined temperature and a net time required for the vibration to propagate through the vibration transmitting plate as an offset time in advance. The correction means subtracts the offset time from the arrival time detected by the detection means, and further corrects the obtained value using a correction amount obtained by the conversion means. Item 3. The coordinate input device according to Item 2. 4. A control means for executing the time keeping means and the conversion means when the vibration input means has shifted from a state in which the vibration input means is in contact with the vibration transmission plate to a state apart from the vibration transmission plate, and further comprising a control means for storing the obtained correction amount. 4. The device according to claim 2, wherein
2. The coordinate input device according to 1. 5. When the state in which the vibration input means has been separated from the vibration transmission plate has continued for a predetermined time or more, a second means for executing the time keeping means and the conversion means and storing the obtained correction amount.
6. The apparatus according to claim 2, further comprising control means.
The coordinate input device according to any one of the above. 6. A coordinate detection method for detecting coordinates based on a propagation time of vibration applied to a vibration transmission plate, wherein the vibration input from the vibration input unit reaches the vibration detection unit. A detecting step of detecting an arrival time until the vibration input means, an obtaining step of obtaining a coordinate position instructed by the vibration input means based on the arrival time detected in the detecting step, provided in the vibration input means. A time-measuring step of measuring a delay time from inputting a signal to a delay means having a delay amount that varies with temperature until a signal corresponding to the signal arrives from the delay means; and a time-measurement result by the time-measuring step. And a correcting step of correcting the arrival time used in the obtaining step based on the above. 7. A conversion step of converting a change amount of the delay time of the delay unit into a change amount of the arrival time to obtain a correction amount, wherein the correction step includes calculating the correction amount obtained in the conversion step. 7. The method according to claim 6, wherein the time of arrival used in the obtaining step is corrected using the method. 8. A holding step of holding a difference between an arrival time detected by the detection step at a predetermined temperature and a net time required for vibration to propagate through the vibration transmission plate as an offset time in advance, 8. The correction step, wherein the offset time is subtracted from the arrival time detected in the detection step, and the obtained value is further corrected using a correction amount obtained in the conversion step. The coordinate detection method described in 1. 9. A control step of executing the timing step and the conversion step when the vibration input means shifts from a state in which the vibration input means is in contact with the vibration transmission plate to a state separated from the vibration transmission plate, and storing the obtained correction amount. 9. The device according to claim 7, wherein
The coordinate detection method described in 1. 10. A second control step of executing the clocking step and the conversion step when the state in which the vibration input means is separated from the vibration transmission plate for a predetermined time or more, and storing the obtained correction amount. The coordinate detection method according to claim 7, further comprising: 11. A computer-readable memory for storing a coordinate detection control program for performing coordinate detection based on the propagation time of vibration applied to a vibration transmission plate, wherein the control program is input to the vibration transmission plate. A code of a detection step for detecting an arrival time until the vibration from the vibration input means reaches the vibration detection means, and a coordinate position designated by the vibration input means based on the arrival time detected in the detection step. From the input of a signal to the delay means, which is provided in the vibration input means and whose delay amount changes with temperature, from when the signal corresponding to the signal arrives from the delay means A code of a timing step for measuring the delay time, and a code of a correction step for correcting the arrival time used in the acquisition step, based on a result of the timing by the timing step. A computer-readable memory, characterized in that it comprises.