JPH07175579A - Device and method for coordinate input - Google Patents

Abstract

PURPOSE:To provide the device and method for coordinate input which calculate coordinates with high precision. CONSTITUTION:Vibration sensors 5a-5d detect an elastic vibration wave inputted from a vibration pen 3 to a vibration transmission plate 8, a signal waveform detecting circuit 9 detects a specific point on the signal waveform outputted from a vibration sensor, and an arithmetic control circuit 1 detects the arrival time of the vibration from the detection result of the signal waveform detecting circuit 9, extracts an effective constant from plural constants regarding the propagation of the vibration wave set in an internal nonvolatile memory, and calculates the position where the vibration is inputted from the detected propagation time and the extracted constant.

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 method therefor, for example, elastic wave vibration input from a vibrating pen is detected by a plurality of vibration sensors arranged on a vibration transmission plate. The present invention relates to a coordinate input device and method for calculating a position designated by a vibrating pen on the basis of the transmission time of.

[0002]

2. Description of the Related Art Conventionally, vibration generated by a vibrating pen is input to a vibration transmitting plate which is an input surface, and a sensor provided on the vibration transmitting plate detects the vibration so that a wave reaches from the vibrating pen to the sensor. A coordinate input device that detects time and outputs the position of the vibrating pen is known. This device detects the plate wave propagating through the vibration transmission plate and calculates the coordinates, and the delay time tg related to the group velocity Vg of the vibration as the arrival delay time of the wave,
The coordinates are calculated by detecting both the delay time tp related to the phase velocity Vp of the vibration. When this device performs coordinate calculation, it is necessary to first measure the distance between the vibration input pen and each sensor, but FIGS. 1 to 3 are diagrams for explaining this distance measurement. A conventional distance calculation principle will be described.

FIG. 1 is a diagram for explaining a signal waveform output from a vibration sensor of a vibration detecting means and a vibration transmission time measuring process based on the signal waveform. Signal to drive the vibrating pen
(a) is applied, and the vibration transmitted from the vibrating pen to the vibration transmission plate by this signal progresses for a time corresponding to the distance to the vibration sensor, and then is detected by the vibration sensor.
FIG. 6B shows a signal waveform detected by the vibration sensor.

Since this vibration is a plate wave, the detected waveform
The propagation velocity (group velocity Vg) of the envelope 421 in (b) and the propagation velocity (phase velocity Vp) of the phase 422 are different. Therefore, depending on the propagation distance in the vibration transmission plate, the detected waveform (b)
The relationship between the envelope 421 and the phase 422 changes.
The distance between the vibration pen and the vibration sensor is detected from the group delay time Tg based on the group velocity Vg and the phase delay time Tp based on the phase velocity Vp.

FIG. 2 is a block diagram showing a configuration for executing waveform processing. A method for detecting the group delay time Tg and the phase delay time Tp will be described with reference to FIG. The signal (b) output from the vibration sensor 50 is amplified to a predetermined level by the preamplifier circuit 51, and then the bandpass filter 58 removes an excessive frequency component to obtain a signal (c). Focusing on the envelope of this signal (c), the velocity at which the waveform propagates is the group velocity Vg, and when a point on a particular waveform, for example, the peak or inflection point of the envelope is detected, the group velocity is
The delay time tg related to Vg is obtained. So the signal (c)
Is input to the envelope detection circuit 52 including an absolute value circuit and a low-pass filter, and the envelope (e) is extracted. Furthermore, this envelope (e)
On the other hand, the gate signal (f) of the portion exceeding the preset threshold value s is generated by the gate signal generation circuit 56 including a multivibrator.

In the following description, an example will be described in which the group delay time tg is detected at the first inflection point of the envelope, that is, the trailing zero crossing point of the signal (d) described later. The signal (e) output from the envelope detection circuit 52 is input to the envelope inflection point detection circuit 53 to obtain a second-order differential waveform (d) of the envelope. The tg detection circuit 54 including a multivibrator outputs the tg signal (i) which is the envelope delay time detection signal of a predetermined waveform by comparing the waveform (d) with the gate signal (f).

On the other hand, regarding the phase delay time tp, the tp detection circuit 57 composed of a zero-cross comparator, a multivibrator, etc. detects the rising zero-cross of the signal (c) during the period when the gate signal (f) is active. ,
It outputs the tp signal (g) which is the phase delay time detection signal. FIG. 3 is a diagram schematically showing the relationship between the group delay time tg, the phase delay time tp and the pen-sensor distance L thus obtained.

Since the plate wave is detected as described above, the group delay time tg cannot be said to have a good linearity with respect to the distance L. Therefore, when the distance L is calculated as the product of the group delay time tg and the group velocity Vg as shown in the equation (1), an accurate result cannot be obtained. L = Vg · tg (1) Therefore, in order to determine the coordinates with higher accuracy, the calculation according to the equation (2) is performed based on the phase delay time tp having excellent linearity.

L = Vptp + nλp (2) where λp: wavelength of elastic wave n: integer That is, the first term on the right side of the equation (2) indicates the distance L0 in FIG. As can be seen from the figure, the difference between the distance L0 and the distance L0 is an integral multiple of the wavelength (the width T ^* of the time axis step is one period of the signal (c), so T ^* = 1 / f )It has become. Therefore, the distance L can be accurately obtained by obtaining the integer n. Therefore, the integer n is given by the formula (1)
It can be obtained by the equation (3) from the equation (2).

N = int {(Vg · tg-Vp · tp) / λp + 1 / N} (3) However, if N: a real number other than 0, for example, N = 2, the linearity of the group delay time tg However, if the generated error is within ± λp / 2, the integer n can be accurately determined. The distance L can be accurately measured by substituting the integer n thus obtained into the equation (2).

[0011]

However, the above-mentioned conventional example has the following problems. In FIG.
Since the gate signal (f) is obtained from the preset threshold value s and the envelope (e) of the signal (c), the part of the signal (c) at which the gate signal (f) occurs depends on the pen pressure of the vibrating pen. , It depends on the level of the signal (c) that changes depending on the slope or the distance L. If the level of the signal (c) decreases, the generation of the gate signal (f) is delayed, and the tp signal (g) which is the phase delay time detection signal is also delayed. That is, when the level of the signal (c) is low, the tp signal (g) is delayed, for example, rises at the timing of tp (Low) in FIG. 1, and conversely, when it is high, the tp signal (g) is increased.
Becomes faster, for example, rises at the timing of tp (High) in FIG. 1, and the rise of the tp signal (g) depends on the level of the signal (c).

As described above, even when the rising edge of the tp signal (g) depends on the level of the signal (c), if the phase period of the signal (c) (for example, the interval between zero cross points) is constant, its influence is It is corrected by the integer n calculated by equation (3). However, the phase period of the signal (c) is not strictly constant, so that an error occurs in the calculated distance L. To prevent this, making the phase period constant means
It is equivalent to making the spectrum of the signal (c) into a single frequency component, that is, it corresponds to a continuous sine wave having a constant period. When this is applied to the coordinate detection device, the signal (c)
Becomes a long signal in time, and even if such a signal can be generated, the following problem remains.

The vibration generated from the vibrating pen reaches the vibration sensor while propagating through the vibration transmission plate (direct wave),
Wave reflected from the end face of vibration transmission plate of finite size (reflected wave)
Also reaches the vibration sensor. When the reflected wave is superimposed on this direct wave and the vicinity of the phase delay detection point of the signal (c) is distorted, the coordinate calculation error becomes extremely large. In order to prevent the influence of this reflected wave, it is necessary to install a sufficient invalid area on the outer peripheral portion of the coordinate input effective area. Therefore, when outputting a stable periodic portion of the signal (C) (portion that can be regarded as a sine wave with a constant period) as the detection point, that portion is located later in time from the beginning of the signal (c). In addition, the ineffective area must be expanded in order to increase the arrival time difference between the direct wave and the reflected wave. This means that the size of the entire device becomes larger than that of the coordinate input effective area, which is a fatal drawback especially for products such as a pen input computer where portability is important.

[0014]

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems, and has the following structure as one means for solving the above problems. That is, the position on the vibration transmission plate designated by the coordinate designating means is calculated based on the arrival time required for the elastic vibration wave inputted from the coordinate designating means to reach the vibration detecting means. A coordinate input method for detecting a predetermined point in the signal waveform output from the vibration detecting means to detect the arrival time, determining the position of the predetermined point in the signal waveform, and the determination result Based on, the effective constant from among a plurality of preset constants related to the propagation of the vibration wave, and the effective arrival reference time from a plurality of arrival reference time related to a preset reference distance, It is characterized in that the position designated by the coordinate designating means is calculated from the detected arrival time, the extracted constant and the arrival reference time.

Further, based on the arrival time required for the elastic vibration wave inputted from the coordinate designating means to the vibration transmitting plate to reach the vibration detecting means, on the vibration transmitting plate designated by the coordinate designating means. A coordinate input device for calculating a position, the arrival time detecting means for detecting a predetermined point in the signal waveform output from the vibration detecting means to detect the arrival time, and the predetermined point on the signal waveform. Extraction means for determining a position and extracting an effective constant from a plurality of constants relating to the propagation of the vibration wave set in advance based on the determination result of the determination means, and the arrival detected by the arrival time detection means. It has a calculating means for calculating the position designated by the coordinate designating means from the time and the constant extracted by the extracting means.

[0016]

According to the above construction, the arrival time is detected by detecting a predetermined point in the signal waveform output from the vibration detecting means,
Based on the result of determining the position of a predetermined point in the signal waveform,
Effective arrival reference time is extracted from a plurality of preset constants related to propagation of vibration waves, and effective arrival reference time is extracted from a plurality of arrival reference times related to preset reference distances. And a coordinate input device and method for calculating the position designated by the coordinate designating means from the extracted constant and the arrival reference time,
For example, even if the phase period of the detection signal waveform is not constant, the coordinates of the vibration input position can be calculated with extremely high accuracy. Moreover, with this configuration, the head portion of the signal waveform can be used as the detection point, the invalid area where coordinates cannot be input can be reduced, and the device can be downsized.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A coordinate input device according to an embodiment of the present invention will be described in detail below with reference to the drawings.

[0018]

First Embodiment [Device Configuration] FIG. 4 is a block diagram showing a configuration example of a coordinate input device according to an embodiment of the present invention. In the figure, reference numeral 1 denotes an arithmetic control circuit, which controls the overall operation of this embodiment and calculates the coordinate position.

Reference numeral 2 denotes a vibrator drive circuit, which amplifies a low-level drive pulse signal supplied from the arithmetic control circuit 1 and supplies the amplified drive pulse signal to a vibrating pen 3 which is a coordinate designating means. The child 4 is driven to generate vibration. The generated vibration is input to the vibration transmission plate 8 via the pen tip 5. The vibration transmission plate 8 is made of, for example, a transparent member such as acrylic or glass, and the coordinate input by the vibration pen 3 is performed by touching a coordinate input effective area (hereinafter referred to as “effective area”) A on the vibration transmission plate 8. Be seen. The oscillator 4
As the vibration frequency of, a value that can generate a plate wave on the vibration transmission plate 8 made of glass or the like is selected. Furthermore, if this vibration frequency is set to a resonance frequency including the pen tip 5, efficient conversion from electrical vibration to mechanical vibration becomes possible.
The elastic wave transmitted to the vibration transmission plate 8 is a plate wave,
It has an advantage that it is less susceptible to scratches and obstacles on the surface of the vibration transmission plate 8 as compared with surface waves.

A vibration isolator 7 is installed on the outer peripheral portion of the vibration transmitting plate 8 to attenuate the reflected wave reflected by the end face of the vibration transmitting plate 8 so that the reflected wave returns to the central portion of the vibration transmitting plate 8. Prevent. 6a to 6d are vibration sensors, and the vibration transmission plate 8
A piezoelectric element or the like disposed near the four corners of the device, which converts mechanical vibration into an electric signal. A signal waveform detection circuit 9 inputs signals output from the vibration sensors 6a to 6d and amplified by an amplification circuit (not shown), and outputs the result of signal processing to the arithmetic control circuit 1. The arithmetic control circuit 1 calculates the coordinate position based on the signal input from the signal waveform detection circuit 9. The details of the arithmetic control circuit 1 and the signal waveform detection circuit 9 will be described later.

Reference numeral 11 is a display such as a liquid crystal display capable of displaying in dot units, and is arranged behind the vibration transmission plate 8. Reference numeral 10 denotes a display drive circuit, which displays a dot at a position on the display 11 corresponding to the position touched by the vibrating pen 3. The dots displayed on the display 11 can be seen through the vibration transmission plate 8. [Arithmetic Control Circuit] The arithmetic control circuit 1 has a predetermined cycle (for example,
Every 5 ms), a drive pulse signal is output to the oscillator drive circuit 2 and the internal timer starts timing.

The vibration input from the vibration pen 3 to the vibration transmission plate 8 arrives at each of the vibration sensors 6a to 6d with a delay depending on the distance from the input position. The signal waveform detection circuit 9 uses the waveform detection processing described below to perform the vibration sensor 6a.
A signal indicating each vibration arrival timing of ~ 6d is generated. The arithmetic and control circuit 1 uses the timing signals output from the signal waveform detection circuit 9 to detect the vibration sensors 6a to 6a.
The vibration arrival time of 6d is detected, the touch position of the vibrating pen 3 is calculated, and the display drive circuit 10 is driven based on the calculated position information to display dots on the display 11. The calculated position information is also output to an external device (not shown) by serial communication or parallel communication.

FIG. 5 is a block diagram showing a configuration example of the arithmetic control circuit 1. In the figure, 31 is a CPU such as a one-chip microcomputer, which is provided with an internal counter, a ROM for storing control procedures, a RAM used for arithmetic operations, and a non-volatile memory for storing constants and the like, and controls the entire embodiment. Take charge. 33 is a timer, which is composed of, for example, a counter,
A reference clock (not shown) is clocked. The timer 33 is CP
The driving pulse signal supplied from the U31 to the vibrator driving circuit 2 starts time counting. This synchronizes the start of timing with the vibration detection by the vibration sensors 6a to 6d,
The time until the vibration is detected (delay time) can be measured.

Reference numeral 35 is an input port for the signal waveform detection circuit 9
The respective vibration arrival timing signals are input from. 34a ~
Each of the latch circuits 34d receives the vibration arrival timing signal from the input port 35 and latches the measured value of the timer 33 at that time. A determination circuit 36 determines whether or not four vibration arrival timing signals have been input to the input port 35. The CPU 31, which has received the signals indicating that the four vibration arrival timing signals have been input from the determination circuit 36, reads the time latched by each of the latch circuits 34a to 34d, that is, the delay time, and executes a predetermined calculation, The coordinate position of the vibration pen 3 on the vibration transmission plate 8 is calculated. Then, the calculated coordinate position information is output to the display drive circuit 10 via the I / O port 37 and also to the interface (not shown) to output the coordinate position of the vibrating pen 3 to the outside. .

[Detection of Vibration Arrival Time and Calculation of Distance L] The method of detecting the vibration propagation time and the method of calculating the distance L have been described with reference to FIGS. Omit it. Note that the tp signal (g) and the tg signal (i) in FIG. 1 are signals input from the signal waveform detection circuit 9 to the arithmetic control circuit 1, and the signal waveform detection circuit 9 is indicated by reference numeral 59 in FIG. One part may be provided corresponding to one vibration sensor, or by selecting the output of the vibration sensor in a time division manner by using an analog switch or the like, one configuration shown by reference numeral 59 in FIG. You can do just that.

As described above, the level of the detection signal waveform (c) shown in FIG. 1 changes due to the writing pressure, etc.
The detection point of the phase delay time tp also changes. Figure 6 is a signal
It is a figure which shows typically the relationship of the group delay time tg, the phase delay time tp, and the distance L when the level of (c) becomes high. In the figure, the solid line shows the relationship when the level of the signal (c) is high, and the broken line shows the relationship when the level is the reference value.

Table 1 shows that the phase velocity Vp and the frequency f obtained by the method of least squares (the definition of the frequency f is defined in the prior art based on the relationship between the phase delay time tp and the distance L obtained at each level of the signal (c). (See section) and an example. In the table, the detection point number indicates the position of the detection point, and the lower the number, the closer to the beginning of the signal (c).

[0028]

[Table 1] As is clear from this table, the phase velocity Vp obtained by the least squares method has different values depending on the detection points. As described above, the distance L is the phase delay time tp, the group delay time t
g and preset constants (phase velocity Vp, group velocity Vg,
Since it is calculated from the frequency f), when the distance L is calculated using the same constant, if the detection point of the phase delay time tp moves, an error will occur in the calculation result, and the coordinate calculation accuracy will be degraded if anything. It will be. That is, in this embodiment, the detection point of the phase delay time tp is specified, and the coordinates are calculated by the phase velocity Vp corresponding to the detection point. Therefore, the constant set for each detection point of the phase delay time tp should be stored in the non-volatile memory of the arithmetic control unit 1 or the like, and a constant effective for calculating the distance L by specifying the detection point should be selected. The coordinate is calculated with high accuracy.

[Identification of Detection Point] Next, a method of identifying the detection point of the phase delay time tp will be described. In FIG. 6, when the reference level detection signal waveform (c) is input, if the group delay time tg at a certain coordinate input point is found, the phase delay time tp for it is found, and the constant of the reference state is used. formula
The integer n can be obtained by (3). That is, if the signal (c) of the reference level is input, the integer n can be uniquely obtained with respect to the group delay time tg. For example, the group delay at the distance γ between the vibration pen 3 and the vibration sensors 6a to 6d. From the time tg, the phase delay time tp, and the equation (3), the integer n = β is obtained.

However, when the level of the signal (c) increases, as shown in FIG. 1, the group delay time tg does not change, but the phase delay time tp becomes tp (High). The obtained integer n becomes β + 1. Therefore, when the group delay time tg is obtained, the integer n = β is obtained at the reference level, but the signal
When the level of (c) is large, n = β + 1 is obtained, so it can be determined that the level is higher than the reference level and is one detection point before the detection point of the reference level.
That is, the detection point can be specified by previously obtaining the relationship between the group delay time tg and the integer n at the corresponding reference level and storing this relationship.

Although it has been described here that the integer n calculated by the equation (3) uses a constant at the reference level, it is converted into an integer (for example, the fractional part is rounded off) because of the property of the equation (3). , An integer n can be accurately obtained by using an approximate constant (for example, a constant at the reference level). Therefore,
By performing the calculation of the integer n using the approximate constant by the formula (3), specify the detection point by comparing with the group delay time tg,
It becomes possible to extract accurate constants (phase velocity Vp, frequency f (= Vp / λp)) from the constants stored in advance, and formula (2)
An accurate distance L can be obtained by.

FIG. 7 is a flow chart showing a procedure example of the above-mentioned processing. In the figure, the group delay time tg and the phase delay time tp are detected in step S1, and the equation is calculated in step S2.
The integer n is calculated by (3), and the group delay time tg is compared with the integer n in step S3 to specify the detection point of the phase delay time tp. Then, a valid constant is extracted from the constants set in step S4, the distance L is calculated by the constant extracted in step S5 and the equation (2), and based on the distance L obtained in step S6. Calculate the coordinates.

[Calculation of Coordinate Position] FIG. 8 is a diagram for explaining the principle of calculating the coordinate position of the vibration pen 3 on the vibration transmission plate 8. In the figure, assuming that the positions of the vibration sensors 6a to 6d arranged near the four corners of the vibration transmission plate 8 are Sa to Sd, respectively, the position of the vibrating pen 3 is based on the principle described above.
Linear distance from P to each vibration sensor position Sa to Sd da to dd
Can be asked. Then, the arithmetic control circuit 1 calculates the vibration transmission plate 8 by the following equation based on the linear distances da to dd.
The coordinates (x, y) of the position P with the center O as the origin O are calculated.

X = (da + db) (da-db) / 2X (4) y = (da + dc) (da-dc) / 2Y (5) where X: Sa-Sb distance Y : Sa-Sc distance In the above formula, an example of calculating the coordinates of the position P from the distance L to the three vibration sensors was explained, but geometrically the coordinates are calculated by two or more vibration sensors. Yes, the number of vibration sensors is set according to the product specifications. In this embodiment, the distance information of the fourth vibration sensor is used to verify the coordinates of the obtained position P. Further, if the distance L between the position P and the position of the vibration sensor is increased, the detection level is lowered and it is easy to be affected by noise.
For example, the coordinates P can be calculated by selecting the outputs of the three vibration sensors having a high detection level.

As described above, according to this embodiment,
Even if the phase cycle of the detection signal waveform is not constant, the coordinates of the vibration input position can be calculated with extremely high accuracy. Moreover, with this configuration, the head portion of the signal waveform can be used as the detection point, the invalid area where coordinates cannot be input can be reduced, and the device can be downsized.

[0036]

[Second Embodiment] A coordinate input device according to a second embodiment of the present invention will be described below. In the second embodiment, the first
About the same configuration as the embodiment, the same reference numerals are given,
Detailed description thereof will be omitted. In this embodiment, the detection point of the phase delay time tp is specified by a method different from that of the first embodiment.

First, assuming that the level of the detected signal waveform (c) is in the reference state, a geometric calculation is performed using the detected group delay time tg, the phase delay time tp, and the reference state constant. Run and determine its effectiveness. That is, the distance L corresponding to each vibration sensor is calculated using the constant corresponding to the reference state and the formulas (1) to (3), and the coordinate P (x, y) is calculated by the formulas (4) and (5). To do. Now, perform the following further calculations,
This will be specifically described with reference to FIG.

In FIG. 9, if the calculated distances da, db, dc are correct, the point P (x, y) is obtained as the position of the vibrating pen 3. However, a large error is included in the distance regarding the vibration sensor arranged at the point Sc, and the distance is calculated as dc ^* ,
It is assumed that a point P ^* (x, y ') is obtained as the position of the vibrating pen 3.
The distance between the vibration pen 3 and each vibration sensor can be obtained by performing back calculation from this coordinate P ^* (x, y '). By comparing the distance obtained by this back calculation with the distance calculated from the delay time, it can be judged whether the correct constant is selected, and if it is judged that the incorrect constant is selected, another A constant is selected, the distance L corresponding to each vibration sensor is calculated using the constant and the formulas (1) to (3), and the formula (4),
The coordinate P (x, y) is calculated by (5).

In this embodiment, such calculation is repeatedly executed, and when the distance calculated backward and the distance calculated from the delay time become equal to all the sensors, the coordinate value at that time is output. . Therefore, accurate and reliable coordinate values can be obtained. As described above, according to this embodiment, the same effect as that of the first embodiment can be obtained.

[0040]

[Third Embodiment] A coordinate input device according to a third embodiment of the present invention will be described below. In the third embodiment, the first
About the same configuration as the embodiment, the same reference numerals are given,
Detailed description thereof will be omitted. In the embodiment described above, the vibration transmission time latched by the latch circuits 34a to 34d includes the phase circuit delay time etp and the group circuit delay time etg as shown in FIG. Furthermore, in these times, in addition to the delay time due to the circuit,
The time when vibration propagates through the pen tip 5 of the vibrating pen 3 is also included. That is, even when the distance between the vibration pen 3 and the vibration sensor is zero, the group delay time tg and the phase delay time tp do not become zero. The errors caused by these are always the same when the vibration is transmitted from the vibration pen 3 to the vibration sensor via the vibration transmission plate 8.

Therefore, for example, the distance Ra from the origin O in FIG. 8 to the position Sa of the vibration sensor 6a is Ra = √ {(X / 2) ² + (Y / 2) ² } ... (6), and the origin O At the vibration pen 3, the vibration transmission time measured from the origin O to the position Sa is tg0 ^* , tp
0 ^* Also, if the time it takes to actually propagate from the origin O to the position Sa is tg0, tpz, tg0 ^* = tg0 + etg… (7) tp0 ^* = tp0 + etp… (8) is there.

On the other hand, the measured value tg ^* , tp at an arbitrary input point P
^* Is tg ^* = tg + etg… (9) tp ^* = tp + etp… (10). Obtaining the difference between Equation (7) and Equation (9) and the difference between Equation (8) and Equation (10), respectively, tg ^* -tg0 ^* = (tg + etg)-(tg0 + etg) = tg-tg0 ... (11) tp ^* -tp0 ^* = (tp + etp)-(tp0 + etp) = tp-tp0… (12), which is the phase circuit delay time et included in each transmission delay time.
p and the group circuit delay time etg are removed. That is, tg = tg ^* -tg0 ^* … (13) tp = tp ^* -tp0 ^* … (14), calculate the distance L using the formulas (1), (2), (3), By adding the distance Ra between the position Sa and the origin O, the distance da between the vibration pen 3 and the vibration sensor 6a can be accurately obtained.

The measured values tg0 ^* , tp0 ^{* at the} origin O and the distances Ra to Rd between each vibration sensor and the origin O are stored in the non-volatile memory of the arithmetic control unit 1 at the time of shipping, and the expression ( 1),
Before calculating (2) and (3), highly accurate measurement is performed by executing equations (13) and (14). Now, here is the detection signal waveform
Considering that the detection point of the phase delay time tp changes depending on the level of (c), the phase circuit delay time etp
Consider the correction method of.

If the phase period of the region where the detection point changes in the detection signal waveform (c) is the same, no error is caused by the correction in the calculation of the integer n by the equation (3). However, the cycles are not the same as described above, and an error will occur if calculations are made assuming the same. That is, as shown in an example in FIG. 10, the phase circuit delay time is e when the level becomes higher than etp when the detection signal waveform (c) is at the reference level.
It becomes tp (High), and this time difference does not match the time difference (= 1 / f) represented by the constant of the reference level, which means that an error occurs.

Therefore, in this embodiment, the detection point of the phase delay time tp is specified, and the coordinates are calculated using the measured vibration transmission times tg0 ^* and tp0 ^* from the origin O to the vibration sensor corresponding thereto. The method for identifying the detection point of the phase delay time tp may be the method of the above-described embodiment.
The vibration transmission time from O to the vibration sensor is stored in advance in the nonvolatile memory of the arithmetic control unit 1 at the time of shipping.

As described above, according to this embodiment,
The phase circuit delay time etp and the group circuit delay time etg included in each transmission delay time can be removed, and the coordinates of the vibration input position can be calculated with extremely high accuracy. As described above, the present invention has been made for the purpose of calculating coordinates with high accuracy. Even if only the constants described in the first embodiment are changed, the criteria described in the third embodiment are used. It is also possible to change only the vibration transmission time value in the distance. Further, both may be combined and carried out at the same time, but excellent effects can be obtained by carrying out either one.

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.

[0048]

As described above, according to the present invention, the arrival time is detected by detecting the predetermined point in the signal waveform output from the vibration detecting means, and the position of the predetermined point in the signal waveform is determined based on the result. Then, an effective constant is extracted from a plurality of preset constants relating to the propagation of the vibration wave, and an effective arrival reference time is extracted from a plurality of arrival reference times relating to the preset reference distance, and the detected constant detection time is detected. It is possible to provide a coordinate input device and method for calculating the position indicated by the coordinate indicating means from the arrival time, the extracted constant and the arrival reference time, and for example, even if the phase cycle of the detection signal waveform is not constant. There is an effect that the coordinates of the vibration input position can be calculated with extremely high accuracy. Moreover, the leading portion of the signal waveform can be used as the detection point, the invalid area where coordinates cannot be input can be reduced, and the device can be downsized.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a signal waveform output by a vibration sensor and a measurement process of a vibration transmission time based on the signal waveform.

FIG. 2 is a block diagram showing a configuration for executing signal waveform processing.

FIG. 3 is a diagram schematically showing the relationship between the obtained group delay time tg, phase delay time tp, and pen-sensor distance L.

FIG. 4 is a block diagram showing a configuration example of a coordinate input device according to an embodiment of the present invention.

5 is a block diagram showing a configuration example of an arithmetic control circuit in FIG.

FIG. 6 is a diagram schematically showing the relationship between the group delay time tg, the phase delay time tp, and the distance L when the level of the detection signal waveform is high.

FIG. 7 is a flowchart showing an example of a coordinate calculation processing procedure of the present embodiment.

FIG. 8 is a diagram illustrating the principle of calculating the coordinate position of the vibrating pen on the vibration transmitting plate according to the present embodiment.

FIG. 9 is a diagram illustrating a method of identifying a detection point of a phase delay time tp according to a second embodiment of the present invention.

FIG. 10 is a diagram showing a phase circuit delay time etp and a group circuit delay time etg included in the measured vibration transmission time.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Arithmetic control circuit 2 Transducer drive circuit 3 Vibrating pen 6a-6d Vibration sensor 7 Anti-vibration material 8 Vibration transmission plate 9 Signal waveform detection circuit 10 Display drive circuit 11 Display

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yuichiro Yoshimura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Masaki Tokioka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Atsushi Tanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (2)

[Claims] 1. Based on the arrival time required for the elastic vibration wave input from the coordinate designating means to the vibration transmitting plate to reach the vibration detecting means, the position on the vibration transmitting plate is designated by the coordinate designating means. A coordinate input method for calculating a position, wherein the arrival time is detected by detecting a predetermined point in the signal waveform output from the vibration detecting means, and the position of the predetermined point in the signal waveform is determined. Based on the determination result, a constant that is effective from among a plurality of preset constants related to the propagation of the vibration wave, and a valid arrival reference time from a plurality of arrival reference times related to the preset reference distance, The coordinate input method is characterized in that the position designated by the coordinate designating means is calculated from the detected arrival time, the extracted constant and the arrival reference time. 2. The vibration transmission plate instructed by the coordinate instruction unit based on the arrival time required for the elastic vibration wave input from the coordinate instruction unit to the vibration transmission plate to reach the vibration detection unit. A coordinate input device for calculating a position, the arrival time detection means for detecting a predetermined point in the signal waveform output from the vibration detection means to detect the arrival time, and the predetermined point in the signal waveform Judgment means for judging the position, based on the judgment result of the judgment means, an effective constant from among a plurality of preset constants related to the propagation of the vibration wave, and a plurality of arrival criteria regarding a preset reference distance Extraction means for extracting the effective arrival reference time from the time, and the arrival time detected by the arrival time detection means,
A coordinate input device, comprising: a calculating unit that calculates the position designated by the coordinate designating unit from the constant and the arrival reference time extracted by the extracting unit.