JP3122509B2 - Coordinate input device and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate input apparatus and method for specifying the position of a vibration source by utilizing, for example, an elastic vibration transmission delay time and performing coordinate input.

[0002]

2. Description of the Related Art Conventionally, coordinate input positions using various input pens, tablets, and the like have been known as devices for inputting handwritten characters and figures to a processing device such as a computer. In this type of apparatus, input image information including characters and figures is displayed or output on a display device such as a CRT display or a recording device such as a printer. Among such coordinate input devices, the following various methods are known as a coordinate detection method in a tablet-type coordinate input device.

[0003] (1) A method comprising a resistance film and a sheet material arranged opposite to each other, and detecting the coordinate value of the pressed point by a change in the resistance value.

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

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

However, the conventional coordinate input device employing these methods has the following disadvantages. That is, in the case of the above-described type using a resistive film (in the case of 1), since the uniformity of the resistor directly affects the accuracy of graphic input, a low antibody having excellent uniformity is required. Is difficult and is not suitable for a device requiring high accuracy. Further, since two resistive films for the X coordinate and the Y coordinate are required, the transparency of the coordinate input surface is reduced. For this reason, there is also a disadvantage that the original is difficult to see when the original is used by being overlapped with the original.

Next, in the case of the type utilizing electromagnetic induction (case 2), the wires are arranged in a matrix, and the coordinate detection accuracy is determined by the position of the wires arranged in a matrix, that is, Since it is directly affected by the processing accuracy, a highly accurate input device becomes very expensive.

[0008] Compared to these methods, the method using ultrasonic waves is a method of detecting the delay time of a wave propagating on a tablet, which is an input surface, and calculating position coordinates. Since no modification has been made, 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.

[0009]

However, in the conventional ultrasonic coordinate input device, the detection signal waveform of the wave output from the sensor varies in amplitude level due to the attenuation of the wave depending on the distance between the vibration input pen and the sensor. Not only does it depend on the pen pressure of the input pen by the operator, but also greatly depends on the input pressure. Therefore, when the delay time is detected as a specific point of signal detection where the detection signal waveform becomes a certain level or more (the level needs to be a certain value or more to distinguish it from noise), the detection signal Without detecting the beginning of the waveform,
Second cycle (FIG. 8B) depending on the level of the detection signal waveform
Alternatively, the third cycle (FIG. 8C) is detected, and a disadvantage occurs in that coordinates are erroneously detected. As a solution to this, it is electrically possible to make the level of the detection signal waveform constant. However, there is a new problem that the number of circuit components increases, resulting in a significant increase in cost, and an increase in the amplification factor. Signal data to be referred to is required for determination, and all input data cannot be used for coordinate calculation, that is, the sampling rate for coordinate calculation is reduced. In consideration of these problems, a method that does not depend on the amplitude level of the detection signal waveform is required to detect the delay time.

In a coordinate input device utilizing ultrasonic waves, if the wavelength of an elastic wave propagating on a vibration transmission plate becomes larger than the thickness of the plate, a plate wave having a different group velocity and phase velocity may propagate. Well known. When this wave is used, the detection point of the phase delay time is set to a point equal to or higher than a certain level, and the group delay time is set to each detection point at the peak of the envelope of the detection signal waveform. FIG. 9 schematically shows the relationship. The group delay time has a continuous but large fluctuation width relationship, and the phase delay time has a stair-like relationship. Such a relationship is due to the property of the plate wave that the phase velocity and the group velocity are different.
At this time, it is impossible to measure accurately with distance calculation based only on the group delay time, and when calculating the distance with the phase delay time, even if the level of the detection signal waveform is electrically constant, attenuation of sound waves, Even if the influence of pen pressure dependency is removed, the relationship between the phase delay time and the distance remains stair-like as shown in FIG.
_When a value of ₀ is output, there is a disadvantage that it is not possible to determine whether the distance is l1 or l2.

In order to solve this problem, a method has been adopted in which both the delay time due to the group velocity and the delay time due to the phase velocity are detected to calculate the coordinates. However, if the group velocity mainly fluctuates due to changes in the tilt of the pen or changes in the velocity constant, a distance error (wavelength error) occurs in units of wavelength in the distance between the vibration input source and the sensor, and the coordinate value accuracy is greatly increased. Cause a decrease.

In order to prevent a decrease in accuracy due to the occurrence of the wavelength error, if the occurrence of the error is detected and the coordinate output at that time is stopped, the coordinate sampling interval is widened and the usability of the input operation is reduced. There was a problem of letting it.

The present invention has been made in view of the above conventional example, and has as its object to provide a coordinate input apparatus and method which suppress the occurrence of wavelength errors and do not reduce the usability.

[0014]

In order to achieve the above object, a coordinate input device according to the present invention has the following configuration. That is, a plurality of vibration sensors are arranged on a coordinate input surface that propagates vibration, the distance between the coordinate pointing device that generates vibration and each of the sensors is measured from the arrival time of the vibration, and the coordinate input by the coordinate pointing device is performed. A coordinate input device that calculates and outputs a designated point in an effective input area on a surface as a coordinate value, wherein a calculating unit that calculates a coordinate value based on the distance, the calculated coordinate value and the measured Determining means for determining the presence or absence of a wavelength error from the distance, and correcting means for correcting the distance by incorporating a predetermined error correction value into each of the distances according to the determination result, Even when the distance from which the coordinate value is calculated includes a wavelength error, the vibration sensor sets the effective input area in which an undeterminable area in which the coordinate value is determined to have no wavelength error by the determination unit. It is arranged to be formed outside the region,
The calculation of the coordinates is repeated until the coordinates calculated based on the corrected distance are determined to have no error by the determination means or the number of times reaches a predetermined number. Further, the coordinate input method of the present invention has the following configuration. That is, on a coordinate input surface that propagates vibration provided with a plurality of vibration sensors, a distance between a coordinate pointing device that generates vibration and each of the sensors is measured from the arrival time of the vibration, and the coordinate input by the coordinate pointing device is performed. A coordinate input method of calculating and outputting a designated point in an effective input area on a surface as a coordinate value, wherein a calculating step of calculating a coordinate value based on the distance, the calculated coordinate value and the measured A determination step of determining the presence or absence of a wavelength error from the distance, and a correction step of correcting the distance by incorporating a predetermined error correction value into each of the distances according to the determination result; Even if the distance from which the coordinate value is calculated includes a wavelength error, the vibration sensor has a previously undeterminable region in which the coordinate value is determined to have no wavelength error by the determination step. Valid input is arranged to be outside the area in the formation, the corrected coordinates calculated distance on the basis of the said determined either step it is determined that no error, the repeated calculation of the coordinate reaches a predetermined number of times.

[0015]

With the above arrangement, the distance from each point designated by the coordinate pointing device to each sensor is measured, and the coordinate value is calculated based on the distance. Thereafter, it is determined whether the calculated coordinate value includes an error, and if there is an error, the distance is corrected by a predetermined correction value. When a new distance is obtained, a new coordinate value is calculated from the value. The above is repeated until it is determined that no error is included.

[0016]

【Example】

[Embodiment 1] FIG. 1 shows the structure of a coordinate input device in this embodiment. In the figure, reference numeral 1 denotes an arithmetic control circuit for controlling the entire apparatus and calculating a coordinate position. Reference numeral 2 denotes a vibrator circuit for driving a pen tip in the vibrating pen 3. Reference numeral 8 denotes a vibration transmission plate made of a transparent member such as an acrylic or glass plate. The coordinate input by the vibration pen 3 is performed by touching the vibration transmission plate 8. Actually, the operation is performed by designating the area within the area indicated by the symbol A indicated by the solid line in the drawing (hereinafter referred to as an effective area) 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. The converting vibration sensors 6a to 6d are fixed.

Reference numeral 9 denotes a signal waveform circuit for outputting a signal obtained by detecting a vibration by each of the vibration sensors 6a to 6d to the arithmetic and control circuit 1. Reference numeral 11 denotes a display such as a liquid crystal display capable of displaying in units of dots, and is disposed behind the vibration transmission plate.
By driving the display drive circuit 10, dots are displayed at the positions traced by the vibration pen 3, and the dots can be seen through the vibration transmission plate 8 (made of a transparent member).

The vibrator 4 incorporated in the vibrating pen 3 is driven by the vibrator driving circuit 2. The driving signal of the vibrator 4 is supplied as a low-level pulse signal from the arithmetic and control circuit 1, amplified by the vibrator driving circuit 2 with a predetermined gain, and applied to the vibrator 4.

The electric drive signal is converted into mechanical ultrasonic vibration by the vibrator 4 and transmitted to the vibration transmitting plate 8 via the pen tip 5.

Here, 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 such as glass. In addition, when the vibrator is driven, a mode of vibrating in the vertical direction in FIG. Further, by setting the vibration frequency of the vibrator 4 to the resonance frequency including the pen tip 5, 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 the surface of the vibration transmitting plate is less susceptible to scratches, obstacles, and the like than surface waves. .

<Description of Arithmetic Control Circuit> In the above-described configuration, the arithmetic control circuit 1 operates every predetermined period (for example, every 5 ms).
A signal for driving the vibrator 4 is output to the vibrator driving circuit 2 and the vibrating pen 3 and time counting by the internal timer (constituted by a counter) is started. And
The vibrations generated by the vibration pen 3 are transmitted to the vibration sensors 6a to 6d.
It arrives with a delay depending on the distance up to.

The vibration waveform detecting circuit 9 includes the vibration sensors 6a to 6a.
6d, and a signal indicating the timing of arrival of vibration at each vibration sensor is generated by a waveform detection process described later. The arithmetic and control circuit 1 inputs this signal for each sensor and outputs the signal to each vibration sensor. Detecting the vibration arrival time from 6a to 6d and calculating the coordinate position of the vibration pen.

The arithmetic and control circuit 1 drives the display drive circuit 10 based on the calculated position information of the vibration pen 3 to control the display on the display 11,
Alternatively, coordinates are output to an external device by serial or parallel communication (not shown).

FIG. 3 is a block diagram showing a schematic configuration of the arithmetic and control circuit 1 according to the embodiment. Each component and its operation will be outlined below.

In the figure, reference numeral 31 denotes a microcomputer for controlling the arithmetic control circuit 1 and the entire coordinate input device, and includes an internal counter, a ROM for storing operation procedures, a RAM for use in calculations and the like, and a nonvolatile for storing constants and the like. It is composed of a memory and the like.

Reference numeral 33 denotes a timer (not shown) for measuring a reference clock (not shown), for example, which is a start for causing the vibrator driving circuit 2 to start driving the vibrator 4 in the vibrating pen 3. When a signal is input, the timing starts. As a result, the start of timing and the detection of vibration by the sensor are synchronized, and the delay time until vibration is detected by the sensors (6a to 6d) can be measured.

The vibration arrival timing signals from the vibration sensors 6a to 6d output from the signal waveform detection circuit 9 are supplied to the latch circuits 34a to 34 via the detection signal input port 35.
is input to d.

Each of the latch circuits 34a to 34d
It corresponds to each of the vibration sensors 6a to 6d, and when a timing signal from the corresponding sensor is received, the time value of the timer 33 at that time is latched. When the determination circuit 36 determines that all the detection signals have been received in this way, it outputs a signal to that effect to the microcomputer 31.

When the microcomputer 31 receives the signal from the determination circuit 36, the latch circuits 34a-34
From the latch circuit, the vibration arrival time from d to each vibration sensor is read, and a predetermined calculation is performed.
The coordinate position of the upper vibration pen 3 is calculated.

Then, by outputting the calculated coordinate position information to the display drive circuit 10 via the I / O port 37, for example, a dot or the like can be displayed at a corresponding position on the display 11. Alternatively, by outputting the coordinate position information to the interface circuit via the I / O port 37, the coordinate value can be output to the external device.

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

FIG. 4 is a diagram for explaining a detection waveform input to the signal waveform detection circuit 9 and a process of measuring a vibration transmission time based on the detection waveform. Hereinafter, the case of the vibration sensor 6a will be described, but other vibration sensors 6b, 6
The same applies to c and 6d.

It has already been described that the measurement of the vibration transmission time to the vibration sensor 6a starts simultaneously with the output of the start signal to the vibrator drive circuit 2. At this time, the drive signal 41 is applied from the transducer drive circuit 2 to the transducer 4. The ultrasonic vibration transmitted from the vibration pen 3 to the vibration transmission plate 8 by the signal 41 advances over 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 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 depends on the propagation distance in the vibration transmission plate 8 during the transmission of the vibration. Will change accordingly. Here, the traveling speed of the envelope 421, that is, the group velocity is Vg, and the phase velocity of the phase 422 is Vp. 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.

First, focusing only on the envelope 421, the speed is Vg. When a point on a specific waveform, such as an inflection point or a signal shown in FIG. The distance between the sensors 6a is
Assuming that the vibration transmission time is tg, d = Vg · tg
.. Given by (3). Although this equation relates to one of the vibration sensors 6a, the other three vibration sensors 6b-6
It can be expressed as the distance between d and the vibration pen 3.

Further, in order to determine coordinates with higher accuracy, processing based on detection of a phase signal is performed. The time from a specific detection point of the phase waveform signal 422, for example, the application of vibration to a zero-cross point after a certain signal level 46 is represented by T.
p45 (a window signal 44 having a predetermined width is generated for the signal 47,
(Compared with the phase signal 422), the distance between the vibration sensor and the vibration pen is as follows: d = Vp · Tp + n · λp (1) 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 = int [(Vg · Tg−Vp · Tp) / λp + 1 / N] (2)

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 it is a change such as tg within ± 1/2 wavelength. The distance between the vibration pen 3 and the vibration sensor 6a can be accurately measured by substituting the determined n into the equation (2). The generation of the signals 43 and 45 for measuring the two vibration transmission times tg and tp described above is performed by the vibration waveform detection circuit 9, which is configured as shown in FIG.

FIG. 5 is a block diagram showing the configuration of the vibration waveform detection circuit 9 of the embodiment.

In FIG. 5, the output signal of the vibration sensor 6a is amplified by a preamplifier circuit 51 to a predetermined level. 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. The timing of the envelope peak is detected by the envelope peak detection circuit 53. In the peak detection circuit, a signal tg (signal 43 in FIG. 4), which is an envelope delay time detection signal having a predetermined waveform, is formed by a tg signal detection circuit 54 composed of a monomultivibrator or the like, and input to the arithmetic and control circuit 1.

On the other hand, reference numeral 55 denotes a signal detection circuit, and the envelope signal 42 detected by the envelope detection circuit 52.
A pulse signal 47 of a portion exceeding a predetermined level threshold signal 46 in 1 is formed. Reference numeral 56 denotes a monostable multivibrator, which opens the gate signal 44 having a predetermined time width triggered by the first rising of the pulse signal 47. Numeral 57 denotes a Tp comparator which detects a zero crossing point at the first rising of the phase signal 422 while the gate signal 44 is open, and the phase delay time signal tp45 is supplied to the arithmetic and control circuit 1. The circuit described above is for the vibration sensor 6a, and the same circuit is provided for other vibration sensors.

<Description of Circuit Delay Time Correction> The vibration transmission time latched by the latch circuit includes a circuit delay time et and a phase offset time toff.
These delay times include not only an electrical delay time of the circuit but also a fixed and physical delay time in a path from driving to detection. The errors caused by these always include the same amount when the vibration is transmitted from the vibration pen 3 to the vibration transmission plate 8 and the vibration sensors 6a to 6d.

Therefore, for example, from the position of the origin O in FIG.
For example, the distance to the vibration sensor 6a is R1 (= x / 2), an input is made at the origin O with the vibration pen 3, and the actually measured vibration transmission time from the origin O to the sensor 6a is tg.
Assuming that the true transmission times from the origin O to the sensor are tgz and tpz, the circuit delay time et and the phase offset toff are as follows: tgz '= tgz + et (4) tpz' = tpz + et + toff (5)

On the other hand, an actual measurement value tg 'at an arbitrary input point P
Similarly, tp 'is tg' = tg + et (6) tp '= tp + et + toff (7) When the difference between (4), (6) and (5) (7) is obtained, tg′−tgz ′ = (tg + et) − (tgz + et) = tg−tgz (8) tp′-tpz '= (tp + et + toff)-(tpz + et + toff) = tp-tpz (9), and the inherent delay time et and the phase offset toff included in each transmission time are removed, and from the position of the origin O The difference between the true transmission delay times according to the distance from the position of the sensor 6a between the input points P can be obtained, and the distance difference can be obtained by using the above equations (1) and (2).

Since the distance from the vibration sensor 6a to the origin O is previously stored in a nonvolatile memory or the like and is known, the distance between the vibration pen 3 and the vibration sensor 6a can be determined. The same applies to the other sensors 6b to 6d.

The actual measured values tgz 'and tpz' at the origin O are stored in a non-volatile memory at the time of shipment.
Before the calculations of the equations (1) and (2), the equations (8) and (9) are executed, and highly accurate measurement can be performed.

<Description of Coordinate Position Calculation (FIG. 6)> Next, the principle of actually detecting the coordinate position on the vibration transmitting plate 8 by the vibration pen 3 will be described.

Now, at the vicinity of the midpoint of the four sides on the vibration transmitting plate 8,
When the two vibration sensors 6a to 6d are provided at the positions of the symbols S1 to S4, the linear distances da to dd from the position P of the vibration pen 3 to the positions of the vibration sensors 6a to 6d are based on the principle described above. You can ask. Further, based on the linear distances da to dd, the arithmetic control circuit 1 can obtain the following equation from the theorem of the square of the coordinates (x, y) of the position P of the vibration pen 3 as follows.

X = (da + db) · (da−db) / 2X (10) y = (dc + dd) · (dc−dd) / 2Y (11) where X is the distance between the vibration sensors 6a and 6b. , Y is the distance between the vibration sensors 6c and 6d.

As described above, the position coordinates of the vibration pen 3 can be detected in real time. As described above, the x coordinate is obtained by the sensors a and b, and the y coordinate is obtained by the sensors c and d.
The coordinates are calculated independently of each other.

If the pen-sensor distance calculated by the equation (2) is correct, the following equation is established.

Da ² − (X / 2 + x) ² −y ² ≦ Eth (12) Dc ² − (Y / 2 + y) ² −x ² ≦ Eth (13) Da: distance between pen and sensor 6 a Dc: pen -Distance between sensors 6c Eth: judgment threshold value Here, the judgment threshold value Eth is logically zero.

When the distance between a certain pen and a sensor has a wavelength error due to the tilt of the pen, the above (12) and (13)
The relationship between the equations is broken, and the left side has a value according to the error. This is because each coordinate value is calculated independently. By using this, Eth is set to be equal to or less than the value at the time of occurrence of the wavelength error in consideration of other practical errors, and the occurrence of the wavelength error can be determined based on whether the expressions (12) and (13) are satisfied.

Further, the wavelength error can be corrected using this determination method.

Now, a case where the distance error of each sensor output is limited to one wavelength and n in the equation (2) is n, n + 1 will be described.

For the distance output of each sensor, n, n + 1
Is correct (when all outputs are n)
, Including 16 types. For 15 combinations including an error, the length for one wavelength is sequentially subtracted from the output distance, coordinate calculation and error determination are performed, and a correct combination is determined.

That is, the distances Da, D between each sensor and the pen
For b, Dc, and Dd, 15 types of coefficients A, B, C, and D are defined as follows.

[A, B, C, D] = [1, 0, 0, 0] [0, 1, 0, 0] [1, 1, 0, 0] [0, 0, 1, 0] [ [1,0,1,0] [0,1,1,0] [1,1,1,0] [0,0,0,1] (14) [1,0,0,1] [0 [1,1,0,1] [1,1,0,1] [0,0,1,1] [1,0,1,1] [0,1,1,1] [1,1,1,1] 1] Using [A, B, C, D] (hereinafter referred to as a correction coefficient), perform distance correction according to the following equation, calculate coordinates, and repeat the calculation for all of the above combinations until the error determination is passed. Do.

Da = Da− (A * λ) (15) Db = Db− (B * λ) (16) Dc = Dc− (C * λ) (17) Dd = Dd− (D * λ) ) (18); λ: wavelength of vibration After correction by equations (15) to (18), equation (12) · (1)
The coordinate value of the combination that passes the determination of 3) is the correct coordinate value.

FIG. 7 shows a flowchart of a processing procedure by the arithmetic and control circuit 1 in performing the error detection and correction processing.

First, when coordinates are designated by the pen 3 by the operator, vibration is detected by the sensor 6 and the transmission delay time is obtained as original data (S71).

After performing the distance calculation including the calculation of n (formula 2) based on the original data (S72), the coordinates of the pen 3 are calculated (S73). This first coordinate calculation is performed in step S7.
The calculation is performed with the data obtained in step 1 as it is.

With respect to the calculated coordinate values, (12)
An error determination is made using equation (13) (S74), and if the determination result is acceptable, the coordinates are output (S75 → S7).
7), proceed to the next coordinate point data acquisition.

If the result of the determination is rejected, the distance is corrected in accordance with the equations (15) to (18) in the order of the table (14) (S75 → S76 → S78 → S73). At this time,
Even if all combinations are completed ([1,1,1,
1]) If the rejection is not satisfied, it is determined that correction is impossible, and the process proceeds to the next data acquisition without performing coordinate output (S78-YES).

In this way, the distance correction, coordinate calculation, and error judgment are repeated until the judgment is passed or until the combination is completed.

By performing the processing in accordance with the above-described flowchart, it is possible to perform distance correction based on the error determination result, and perform accurate coordinate output without missing a coordinate sequence.

The above description is only for one wavelength error. However, the present invention is not limited to this, and can be applied to a plurality of wavelength errors. In that case, the number of combinations may be increased, and correction, coordinate calculation, and determination may be performed in the same manner as described above. For example, if it is intended to correct up to an error of two wavelengths up to n, n + 1, n + 2, the combination of the correction coefficients [A, B, C, D] is changed to {0, 1,} instead of {0, 1}. Create｝ as an element. Therefore, the number of combinations to be tried at the time of determination is increased from 2 ⁴ −1 = 15 to 3 ⁴ −1 = 80. By doing so, the number of cases in which a conclusion that correction is impossible is reduced, and the missing coordinate sequence can be further reduced.

Although the present embodiment has been described with respect to a plate wave asymmetric wave, the present invention is not limited to this, and any apparatus which has a plurality of distance references and performs coordinate calculation can be applied to this embodiment. it can.

[0070]

[Other embodiments]

[Embodiment 2] In the above embodiment, the order of the distance correction is determined in advance by the correction coefficient (14). Can be shortened.

Although n obtained by the equation (2) is used after being converted into an integer, the difference between the value before conversion into an integer and the value after conversion into an integer is Δn.
Δn = n−int (n) (19)

This Δn takes a value in the range of ± 0.5,
When it exceeds the range of 0.5, a wavelength error occurs.

As in the first embodiment, the determination range of n is n,
When n + 1 is set, when a wavelength error occurs, the value of Δn exceeds +0.5.

If Δn is expressed as −0.5 + α, assuming that the value of α is about 0 to +0.5, the value of Δn is minus in the distance data having a wavelength error of +1 wavelength. There is a high probability.

If the correction coefficient (14) is used in order, the correction for +1 wavelength is performed in the order of A, B, C, and D. Therefore, the coefficients A to D used in the equations (15) to (18) are By rearranging in order of small Δn, a combination that passes the determination can be found earlier, and the calculation time can be reduced by reducing the number of repetitions until the end of the determination.

Now, assuming that the relationship between Δn when calculating the distances between the pen and the sensors 6a to 6d is Δnb <Δnd <Δna <Δnc (20); Δni: Δn in the sensor i, Expressions (15) to (18) are as follows: Da = Da− (C * λ) (15 ′) Db = Db− (A * λ) (16 ′) Dc = Dc− (D * λ) (17 ′) Dd = Dd- (B * [lambda]) (18 ') The coefficients are rearranged, and correction and determination may be performed as described above.

In the above example, the coefficients are rearranged. However, the same effect can be obtained by rearranging the order of each set of the correction coefficients (14).

Although the present embodiment is an example in which the correction coefficients are rearranged by focusing on Δn, the rearrangement may be performed in accordance with another reference, for example, a signal level. As described above, by performing the distance correction based on the determination result of the presence or absence of the error, the wavelength error generated by the pen tilt or the like is corrected, and even for various variations such as the tilt and the end face reflection,
It has become possible to perform stable and high-precision coordinate output without missing a coordinate sequence. [Third Embodiment] In the coordinate input device of the first embodiment, when the relationship between the sensor and the effective area is not properly set, a wavelength error actually occurs in the above-described determination formulas (12) and (13). In such a case, the determination may not be possible. FIG. 10 shows an example.

The distance outputs da and dc of the sensors 6a and 6c
Each have an error of wavelength λ, and the original coordinates of P (x,
If y) is calculated as P ′ (x ′, y ′) due to the wavelength error, if the relationship between the effective area A and the sensor position is not appropriate,
Although (12) (1)
The judgment of 3) is passed, and erroneous coordinate output is performed. At the original correct coordinates P (x, y), the expression (1)
The left side of 2) is 0, which is expressed by the following equation.

Da ² − (X / 2 + x) ² −y ² = 0 (12 ′) The same applies to equation (13).

Dc ² − (Y / 2 + y) ² −x ² = 0 (13 ′) The undetermined point is calculated by using the equation (12 ′) · (13 ′) as the point P ′
(X ′, y ′) is also satisfied. Therefore, the undetermined point is defined by the following equations (19) and (20).

(X ′ ² + y ′ ² ) − (x ² + y ² ) = (x′−x) X (19) (x ′ ² + y ′ ² ) − (x ² + y ² ) = (y′− y) Y (20) Here, x 'and y' are coordinate values calculated from the distance including the wavelength error, x and y are original correct coordinate values, and X and Y are between sensors for determining each coordinate. Is the distance. (19), (2)
Equation (0) is obtained when the distance between the coordinates shifted by the wavelength error and the original correct coordinates is equal to the product of the distance between the sensors used for the coordinate calculation and the difference between the correct and incorrect coordinates.
The condition (13) is satisfied.

The judgment threshold value Eth used in the judgment formula
Indeterminable region Considering ^{the, - Eth <(x '2} + y' 2) - (x 2 + y 2) - (x'-x) · X <Eth ... (19 ') - Eth <(x ' ² + y' ² )-(x ² + y ² )-(y'-y) · Y <Eth (20 ′). If the threshold value Eth is large, the range is naturally expanded. . In FIG. 11, 111 and 112 are Eth
Is properly taken, (19 ') and (20') indicate the coordinate areas where each of them is satisfied, and the intersection points are areas where determination is impossible.

In order to prevent such an area from being generated in the effective area, the sensor position is determined based on equations (19 ') and (20') so that the undetermined area is outside the effective area.
X and Y may be determined.

FIG. 12 shows an undetermined area when the distance between the sensors is changed according to the equations (19) and (20). The intersection of 121 and 122 is outside the effective area and can be determined in all areas. In this case, X is lengthened and Y is shortened. However, if there is a restriction on the sensor position, it may be handled by changing the effective area.

As described above, the sensor in which the error-impossible area defined by the distance from the correct coordinate position and the distance between the sensors caused by the wavelength error is formed outside the effective input area. Is provided, accurate coordinates can be calculated in the entire effective area.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of one device. Needless to say, the present invention can be applied to a case where the present invention is achieved by supplying a program to a system or an apparatus.

As described above, the coordinate input device and method according to the present invention have an effect that the occurrence of wavelength errors is suppressed and the usability is not reduced.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a configuration of a vibration pen.

FIG. 3 is a diagram showing an internal configuration of an arithmetic control circuit in the embodiment.

FIG. 4 is a timing chart of signal processing.

FIG. 5 is a block diagram of a signal waveform detection circuit.

FIG. 6 is a diagram showing a coordinate system of the coordinate system input device.

FIG. 7 is a flowchart of a correction procedure.

FIG. 8 is an explanatory diagram of a relationship between a delay time and a signal waveform level.

FIG. 9 is an explanatory diagram for a distance between a phase delay time and a group delay time of a body wave.

FIG. 10 is an explanatory diagram of a determination impossible point.

FIG. 11 is an explanatory diagram of an undeterminable area.

FIG. 12 is an explanatory diagram for excluding an undeterminable area from a coordinate input effective area;

[Description of Signs] 1 Arithmetic control circuit, 2 Vibrator drive circuit, 3 Vibration input pen, 4 Vibrator, 5 Pen tip, 6a to 6d Vibration sensor, 7 Anti-vibration material, 8 Vibration transmission plate, 9 Signal waveform detection circuit It is.

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yuichiro Yoshimura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Katsuyuki Kobayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (56) References JP-A-2-130612 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G06F 3/03 340 G06F 3/03 380

Claims (8)

(57) [Claims] 1. A plurality of vibration sensors are provided on a coordinate input surface for propagating vibration, and a distance between a coordinate pointing device for generating vibration and each of the sensors is measured from an arrival time of the vibration. A coordinate input device that calculates and outputs a designated point in an effective input area on the coordinate input surface as a coordinate value, wherein a calculating unit that calculates a coordinate value based on the distance, the calculated coordinate value and the measurement Determining means for determining the presence or absence of a wavelength error from each of the distances, and correcting means for correcting the distance by incorporating a predetermined error correction value into each of the distances according to the determination result, The plurality of vibration sensors are used to calculate a distance based on which a coordinate value is calculated.
Even if the separation contains a wavelength error,
The judgment means judges that there is no wavelength error.
Arranged so that the undefined area is formed outside the valid input area.
Is location, the corrected coordinates calculated distance on the basis of the said or it is determined that no error by the determining means, the coordinate input device and repeating the calculation of the coordinate reaches a predetermined number of times. 2. The coordinate input device according to claim 1, wherein each component of the coordinates is calculated independently from a distance between a different sensor and the pointing device. 3. The method according to claim 2, wherein the error is a quantization error when quantizing a wave number of the vibration, and a combination for correcting the respective distances is determined according to a value of the quantization error. 2. The coordinate input device according to 1. 4. The coordinate input device according to claim 1, wherein when the number of the corrected combinations reaches a predetermined number, coordinate output is not performed. 5. On a coordinate input surface on which a plurality of vibration sensors are arranged and which propagates vibration, a distance between a coordinate pointing device that generates vibration and each of the sensors is measured from the arrival time of the vibration, and the distance is measured by the coordinate pointing device. Valid input on the coordinate input surface
A coordinate input method of calculating and outputting a designated point in a region as a coordinate value, comprising: a calculating step of calculating a coordinate value based on the distance; and a wavelength from the calculated coordinate value and the measured distance. a determination step of determining whether the error, according to the judgment result, wherein each and a correction step of correcting the distance by incorporating a predetermined error correction value to the respective distances, the plurality vibration sensors are coordinates Distance from which the value was calculated
Even if the separation contains a wavelength error,
It is determined that there is no wavelength error in the determination step.
Arranged so that the undefined area is formed outside the valid input area.
Is location, the corrected distance coordinates calculated on the basis of the said determined either step it is determined that no error, the coordinate input method comprising repeating the calculation of the coordinate reaches a predetermined number of times. 6. The coordinate input method according to claim 5, wherein each component of the coordinates is independently calculated from a distance between a different sensor and the pointing device. 7. The method according to claim 1, wherein the error is a quantization error when quantizing a wave number of the vibration, and a combination for correcting the respective distances is determined according to the value of the quantization error. 5. The coordinate input method according to 5. 8. The coordinate input method according to claim 5, wherein the coordinate output is not performed when the number of the corrected combinations reaches a predetermined number.