JPH08314617A - Device and method for coordinate input - Google Patents

Abstract

PURPOSE: To provide a coordinate input device which is stable and highly precise without an (n) jump by deriving a phase difference on the basis of differences between propagation delay times derived by a 1st and a 2nd deriving means respectively and a correction value stored in a correction value storage means. CONSTITUTION: In the microprocomputer 31' of an arithmetic circuit, a nonvolatile memory, for example, is provided with a constant storage means 31a which stores plural values as constants corresponding to group speeds used to find phase differences from a reference phase and a correction value storage means 31b which stores the propagation delay time of a signal, based upon the group speed and phase speed, behind a specific point of a vibration propagation plate as the correction value. When an operator indicates coordinates with a vibration pen, a vibration sensor detects the vibration to obtain vibration transmission delay times tg' and tp'. The vibration propagation time tg' between those vibration transmission delay times tg' and tp' is compared with a transmission delay time tgz' at the origin 0 which is stored in the correction value storage means 31b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects elastic wave vibration input from, for example, a vibrating pen by a plurality of sensors provided on the vibration transmitting plate, and detects elastic wave vibration input from the vibrating pen to the vibration transmitting plate. The present invention relates to a coordinate input device and a coordinate input method for detecting the coordinates of a vibration input point by a vibration pen based on a propagation delay time related to a group and a phase.

[0002]

2. Description of the Related Art An ultrasonic coordinate input device is a method of calculating a position coordinate by detecting a delay time of a wave propagating on a tablet which is an input surface. Because it is not applied at all,
It is possible to provide an inexpensive device. Moreover, if a transparent plate glass is used for the tablet, it is possible to configure a coordinate input device having higher transparency than other methods.

FIG. 5 is a block diagram showing a schematic configuration of a conventional ultrasonic type coordinate input device.

Reference numeral 1 in the figure denotes an arithmetic control circuit for controlling the operation of the entire apparatus and for calculating the coordinate position. Reference numeral 2 denotes a vibrator drive circuit for vibrating the pen tip inside the vibrating pen 3. Reference numeral 8 is a vibration transmission plate made of a transparent member such as acrylic or glass plate. Coordinates are input by the vibration pen 3 by touching the vibration transmission plate 8. That is, the vibrating pen 3 is designated by designating the area within the area indicated by the solid line A in FIG.
It is possible to calculate the position coordinates of.

A vibration sensor 6 such as a piezoelectric element for converting mechanical vibration into an electric signal is provided outside the central portion of each side of the effective area.
a to 6d are fixed. Further, in order to prevent (reduce) the propagating wave from being reflected at the end surface of the vibration transmitting plate 8 and returning to the central portion of the reflected wave, a vibration isolator 7 is provided on the outer periphery of the vibration transmitting plate 8. Has been.

Reference numeral 9 is a signal waveform detection circuit for outputting a signal in which vibration is detected 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 that can display dots, and is arranged behind the vibration transmission plate 8.

Then, it is possible to display a dot at a position traced by the vibrating pen 3 by driving the display driving circuit 10 and see it through the vibration transmitting plate 8 (made of a transparent member).

The vibrator 4 built in the vibrating pen 3 is driven by the vibrator driving circuit 2. The drive signal for the vibrator 4 is supplied as a low-level pulse signal from the arithmetic control circuit 1, amplified by a predetermined gain by the vibrator drive circuit 2, and then applied to the vibrator 4. The electrical drive signal is
It is converted into mechanical vibration by the vibrator 4, and is transmitted to the vibration transmission plate 8 via the pen tip 5.

Here, the vibration frequency of the vibrator 4 is selected to a value capable of generating a plate wave on the vibration transmission plate 8 such as glass. Further, when the vibrator 4 is driven, a mode in which the vibration transmitting plate 8 vibrates in the vertical direction of FIG. 6 is selected. Further, by setting the vibration frequency of the vibrator 4 to the resonance frequency including the pen tip 5, efficient vibration conversion can be performed.

The elastic wave transmitted to the vibration transmitting plate 8 as described above is a plate wave, and has the advantage that it is less susceptible to scratches and obstacles on the surface of the vibration transmitting plate 8 compared to surface waves. Have.

Next, the arithmetic control circuit 1 will be described.

In the above configuration, the arithmetic control circuit 1 outputs a signal for driving the vibrator driving circuit 2 and the vibrator 4 in the vibrating pen 3 at every predetermined cycle (for example, every 5 msec.), And the internal timer ( (Consisting of counters) to start timing. Then, the vibration generated by the vibrating pen 3 propagates on the vibration transmission plate 8 and arrives after being delayed according to the distance to the vibration sensors 6a to 6d.

The vibration waveform detection circuit 9 includes vibration sensors 6a.
The signal from 6d is detected, and the signal showing the vibration arrival timing to each vibration sensor 6a to 6d is generated by the waveform detection processing described later. The signal for each sensor is input to the arithmetic control circuit 1. The display 11 is driven by the display drive circuit 10 based on the detection of the vibration transmission time to each of the vibration sensors 6a to 6d and the position information of the vibration pen 3.
Display is controlled, or coordinates are output to an external device by serial or parallel communication (not shown).

FIG. 7 is a block diagram showing a schematic configuration of the arithmetic control circuit 1, and each component and its operation outline will be described.

In the figure, 31 is a microcomputer for controlling the operation of the arithmetic control circuit 1 and the coordinate input device as a whole, and stores an internal counter, a ROM storing a processing procedure, a RAM used for calculation, a constant and the like. It is composed of a non-volatile memory or the like. Reference numeral 33 is a timer (not shown) for counting a reference clock, which is composed of, for example, a counter, and outputs a star and a signal for causing the vibrator drive circuit 2 to start driving the vibrator 4 in the vibrator pen 3. When you enter it, the timing starts. This synchronizes the start of timing with the vibration detection by the sensor, and the sensor 6a
The delay time until the vibration is detected can be measured by ~ 6d.

The vibration arrival timing signals from the vibration sensors 6a to 6d output from the signal waveform detection circuit 9 are latched via the detection signal input port 35 to the latch circuits 34a to 34a.
It is input to d. Each of the latch circuits 34a to 34d corresponds to each of the vibration sensors 6a to 6d, and when receiving the timing signal from the corresponding sensor, latches the measured value of the timer 33 at that time.

In this way, when the determination circuit 36 determines that all the detection signals have been received, it outputs a signal to that effect to the microcomputer 31. When the microcomputer 31 receives the signal from the determination circuit 36, the vibration transmission time from the latch circuits 34a to 34d to each vibration sensor is read from the latch circuit, a predetermined calculation is performed, and the vibration on the vibration transmission plate 8 is vibrated. The coordinate position of the pen 3 is calculated.

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

Next, referring to FIGS. 8 and 9, the vibrating pen 3 will be described.
The principle of measuring the vibration transmission time from the to the vibration sensors 6a to 6d will be described.

FIG. 8 is a diagram for explaining a detected waveform input to the signal waveform detection circuit 9 and a vibration transmission time measuring process based on the detected waveform. In addition, here, the vibration sensor 6
The case of a will be described, but other vibration sensors 6
The same applies to b, 6c, and 6d.

It has already been described that the measurement of the vibration transmission time to the vibration sensor 6a is started at the same time as the output of the start signal to the vibrator drive circuit 2. At this time, the drive signal 41 is applied from the vibrator drive circuit 2 to the vibrator 4.
The ultrasonic vibration transmitted from the vibration pen 3 to the vibration transmission plate 8 by the signal 41 progresses for a time tg corresponding to the distance to the vibration sensor 6a and then is detected by the vibration sensor 6a.

The signal indicated by 42 in the figure is the vibration sensor 6a.
Shows the signal waveform detected by. Since the vibration used here is a plate wave, the relationship between the envelope 43 and the phase 42 of the detected waveform with respect to the transmission distance in the vibration transmission plate 8 changes according to the transmission distance during the vibration transmission. . Here, the group velocity, which is the traveling velocity of the envelope 43, is Vg,
In addition, the phase speed, which is the speed at which the phase 42 advances, is Vp.
If the group velocity Vg and the phase velocity Vp are known, the distance between the vibration pen 3 and the vibration sensor 6a can be calculated from the vibration transmission time.

The calculation process of the distance between the vibration pen 3 and the vibration sensor 6a is performed as follows. First, focusing only on the envelope 43, its speed is Vg,
When a point on a certain specific waveform, for example, the first zero-cross point of the signal 44 which is the second differential waveform of the envelope 43 is detected as the inflection point of the envelope 43, the distance d between the vibration pen 3 and the vibration sensor 6a is , Its vibration transmission time is t
g ′ is given by d = Vg · tg (1) (where tg is the delay time of the circuit or the like).
value subtracted from g '). This equation relates to the vibration sensor 6a, but the other three vibration sensors 6b
The distance between ~ 6d and the vibrating pen 3 can be similarly expressed.

Further, in order to determine a finer coordinate position, processing based on the detection of the phase signal is performed. A time from a specific detection point of the phase waveform signal 42, for example, vibration application to a zero cross point after a certain predetermined signal level 431 is t.
If p'47 (obtained by generating the gate signal 46 of a predetermined width from the time exceeding the level 431 and comparing with the phase signal 42), the distance between the vibration sensor 6 and the vibration pen is d = n. λp + Vp · tp (2) (where tp is the value obtained by subtracting the delay time of the circuit or the like from tp ′). Here, λp is the wavelength of the elastic wave, and n is an integer.

From the above equations (1) and (2), the above integer n
Is expressed as n = int [(Vg · tg−Vp · tp) / λp + 1 / N] (3).

Here, N is an appropriate real value other than "0". For example, if N = 2.0, the n value of the equation (2) can be correctly determined even if the detected values of tg and tp having an error within ± 1/2 wavelength are obtained. By substituting N obtained as described above into the equation (2), the vibration pen 3
The distance between the vibration sensor 6a and the vibration sensor 6a can be accurately measured.

The above-mentioned two vibration transmission times tg 'and t
The signal waveform detection circuit 9 for generating the signals 45 and 47 for measuring p ′ is configured as shown in FIG.

FIG. 9 is a block diagram showing the configuration of the signal waveform detection circuit 9 of the conventional coordinate input device.

In the figure, the output signal of the vibration sensor 6a has an extra frequency component of the detection signal removed by a band pass filter 511, and an envelope detection circuit 52 composed of, for example, an absolute circuit and a low pass filter. Is input to, and only the envelope of the detection signal is extracted. The timing of the envelope inflection point is detected by the envelope inflection point detection circuit 53.

The peak detection circuit is a signal tg 'which is an envelope delay time detection signal of a predetermined waveform by a tg signal detection circuit 54 composed of a mono multivibrator or the like.
(Signal 45 in FIG. 8) is formed and input to the arithmetic control circuit 1.

On the other hand, reference numeral 55 is a signal detection circuit, and the envelope signal 43 detected by the envelope detection circuit 52.
The pulse signal of the portion exceeding the threshold signal 431 of the predetermined level is formed. 56 is a monostable multivibrator, which opens the gate signal 46 of a predetermined time width triggered by the first rising edge of the pulse signal. Reference numeral 57 denotes a tp converter, which is a phase signal 42 while the gate signal 46 is open.
The first rising zero-cross point is detected, and the phase delay time signal tp′47 is supplied to the arithmetic control circuit 1. The circuit described above is for the vibration sensor 6a, and the same circuit is provided for the other vibration sensors 6b to 6d.

Next, the circuit delay time correction processing will be described.

What is actually measured by the signal waveform detection circuit 9 is tg 'and tp' which include the offset for the delay time in the vibrating pen 3 or in the circuit, but the equations (2) and (3) are used. When substituting into the equation, it is necessary to subtract the offset amount and restore it to tg and tp.

The vibration transmission time latched by the latch circuits 34a to 34d includes the circuit delay time et and the phase offset time toff. The error caused by these is always included in 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, the distance from the position of the origin O in FIG. 10 to the vibration sensor 6a is R1 (= X /
2) and the measured vibration transmission time from the origin O to the sensor 6a measured by inputting with the vibration pen 3 at the origin O is t.
If gz ', tpz' and the true transmission time from the origin O to the sensor 6a are tgz ', tpz', these are tgz '= tgx + et (4) with respect to the circuit delay time et and the phase offset toff. ) Tpz '= tpz + et + toff ... (5).

On the other hand, the measured value tg 'at an arbitrary input point P,
Similarly, tp ′ is tg ′ = tg + et (6) tp ′ = tp + et + toff (7). When the difference between the equations (4) and (6) and the equations (5) and (7) is obtained, tg'-tgz '= (tg + et)-(tgz + et) = tg-tgz. (8) tp'-tpz '= (tp' + et + toff)-(tpz + et + toff) = tp-tpz (9), which is the circuit delay time et and the phase offset toff included in each transmission time. Is eliminated, the true difference in transmission delay time according to the distance from the position of the origin O to the input point P with the position of the sensor 6a as the starting point can be obtained, and the equations (2) and (3) are used. For example, the distance difference can be obtained.

The distance from the vibration sensor 6a to the origin O is
The distance between the vibration pen 3 and the vibration sensor 6a can be determined because it is stored in advance in a non-volatile memory or the like and is known. The other sensors 6b to 6d can be similarly obtained.

The measured values tgz 'and tpz' at the origin O are stored in the non-volatile memory at the time of assembling at the factory or at the time of shipment, and are stored in the above (8) before calculation of the equations (2) and (3). ) And (9) are executed, and highly accurate measurement can be performed.

Next, the principle of detecting the coordinate position on the vibration transmission plate 8 by the actual vibration pen 3 will be described.

Now, in the vicinity of the midpoint of four sides on the vibration transmission plate 8, 4
When the two vibration sensors 6a to 6d are provided at the positions S1 to S4, the linear distances da to dd from the position P of the vibrating pen 3 to the positions of the respective vibration sensors 6a to 6d are calculated based on the principle described above. You can ask.

Further, in the arithmetic control circuit 1, this linear distance d
Based on a to dd, the coordinates (x,
It can be obtained as in the following equation from the Pythagorean theorem of y).

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

Further, in the equations (2) and (3), in order to calculate the distance, the values of Vg, Vp, and λp (= Vp / f) corresponding to the group velocity, the phase velocity, and the wavelength are calculated. It is necessary to set it in advance. Conventionally, for example, as disclosed in Japanese Patent Application No. 5-302890, the above f is calculated from a plurality of tp of detected vibrations, and Vp corresponding to the phase velocity is calculated from the thickness of the vibration transmission plate 8 to transmit the vibration. Vg corresponding to the group velocity is calculated from the plate thickness of the plate 8 and the above f and Vp are calculated.
Therefore, λp is set. And Vg, Vp and λp
(= Vp / f) is stored in a non-volatile memory or the like.

As described above, the position coordinates of the vibrating pen 3 can be detected in real time.

[0045]

However, in the above-mentioned conventional coordinate input device, when the n value is erroneously calculated in the equation (3), a distance error of several mm or more, which corresponds to one wavelength or more, is generated. There was a problem that occurs.

The erroneous detection of the n value (hereinafter referred to as n skips) will be described in detail below. The cause of n jump is due to the waveform deformation due to the transmission distance of the detection signal, the waveform deformation due to the superposition of the reflected wave from the plate end surface, the waveform deformation due to the inclination of the vibrating pen 3 or the writing pressure, and the environment (temperature, humidity) during use. Circuit delay time et, change in phase offset toff, and Vg, V
Examples of this include setting deviations of p and λp. In particular, waveform deformation associated with the transmission distance of the detection signal is one of the major causes.

FIG. 11A shows the frequency characteristic of the detection signal of the vibration sensor analyzed by the spectrum analyzer. When the repetition pulse frequency of the drive signal 41 to the vibration pen 3 is set to 500 kHz, one of the natural vibration frequencies of the vibration pen 3 is 50 kHz.
Since it is 0 kHz, the frequency peak is 500 as shown.
It becomes kHz. However, it is difficult to say that vibrations of a single frequency are propagated because a plurality of peaks also exist near 500 kHz.

As described above, the vibration used in the ultrasonic coordinate input device is a plate wave, and the one detected by the vibration sensors 6a to 6d in the configuration of FIG. 5 is Lam in the plate wave.
This is the vibration of b wave in Ao mode. The propagation speed of the plate wave varies depending on the plate thickness of the propagating vibration transmitting plate 8 and the frequency of the vibration itself.

FIG. 11B shows the propagation velocity and frequency of the plate wave.
The relationship with the plate thickness is shown. Assuming that the glass plate thickness is 1.2 mm and is constant in the figure, the vibration frequency is 500 to 600 k.
It is understood that the phase propagation velocity Vp changes by about 120 m / s and the group propagation velocity Vg changes by about 90 m / s when changing to Hz. Vibration of a plurality of frequency components as shown in FIG.
Waveform deformation occurs when propagating at a speed as shown in FIG.

FIG. 12 shows the vibration pen = distance L between vibration sensors.
The output waveform (the detection signal waveform of the vibration sensor) of the preamplification circuit 51 when V is changed is shown. The signal waveforms are clearly different between near and far. Since the propagation velocity differs depending on the frequency described in FIG. 11B, as the vibration propagates, the high-frequency component with a high velocity spreads forward of the waveform,
The slow component spreads backwards. That is, the detected waveform spreads on the time axis at a long distance. If the group delay time tg is actually detected with the peak position as the specific point, the peak position moves in proportion to the distance according to the group velocity of the vibration of the center frequency component of 500 kHz, so that a linear tg is obtained.

However, since it is desirable to detect tg with the front of the waveform, which is less susceptible to the influence of reflection, as the specific point (which makes it possible to reduce the size of the device), the inflection point of the envelope as in the prior art. If t is detected, a linear tg cannot be obtained.

FIG. 13 shows a plot of vibration transmission distance (vibration pen = distance between vibration sensors) and detected values of tg and tp. tp is obtained as a stepwise discontinuous group of parallel straight lines at equal intervals, and tg is obtained as a curved curve as shown in the figure. In the figure, the pen-sensor distance is omitted from the origin O only for the sake of simplicity. The asymptote on the tg side is a straight line parallel to the velocity at the peak position of the envelope, and is drawn so as to contact tg at the origin O.

When the inflection point is detected and the waveform deformation is not linear (Δt in FIG. 12 is not proportional to the distance), tg does not become a straight line and the vibration transmission distance is small. It is observed that the group velocity is slow, and the group velocity becomes fast when the vibration transmission distance is large. It is considered that this is because vibrations of non-single frequency components as shown in FIG. 11 propagate through the vibration transmission plate 8.

FIG. 14 shows the value obtained by calculating the n value from the above equation (3) from tg and tp as shown in FIG. 12, and the difference between the value before being converted into an integer (int processing) as the following equation is ΔN. Show.

ΔN = (Vg · tg−Vp · tp) / λp−int [(Vg · tg−Vp · tp) / λp + 1/2] (12) In FIG. 14, the distance between the vibrating pen and the vibration sensor is 125 mm
10 is set as the origin in FIG. 10, and the toff in the circuit delay time correction process is calculated and subtracted, so that ΔN is zero at the origin O. Further, Vg in the equation is set to a value approximately midway between the slow group velocity and the fast group velocity.

As is apparent from FIG. 14, the group delay time tg
The influence of the non-linearity of Δ appears as a result of ΔN swinging to the negative side at a short distance and a long distance. In addition to the above, the waveform deformation due to the superposition of the reflected waves described above, the waveform deformation due to the inclination or the writing pressure of the vibrating pen 3, the circuit delay time et due to the environment (temperature, humidity) during use, the change in the phase offset toff, and Vg, When the setting deviations of Vp and λp are added, n jumps occur. Particularly, since the configuration is such that toff is obtained at the origin O in FIG. 10, near the middle of the transmission distance (hundreds of tens of millimeters), ΔN due to the waveform deformation accompanying the transmission distance is close to zero. The probability of occurrence of jumps is high.

As described above, the conventional ultrasonic type coordinate input device has a problem that erroneous detection of coordinates on the order of several millimeters of n jumps occurs.

In view of the above-mentioned conventional problems, it is an object of the present invention to provide a stable and highly accurate coordinate input device and a coordinate input method without n jumps.

[0059]

To achieve the above object, a coordinate input device according to a first aspect of the present invention provides a vibration input means for inputting a vibration and a vibration input by the contact of the vibration input means. A vibration transmitting member that propagates, a vibration detecting unit that is provided on the vibration transmitting member and detects the vibration input by the vibration input unit, and a group velocity formed by the vibration detected by the vibration detecting unit. First deriving means for deriving a signal propagation delay time; second deriving means for deriving a signal propagation delay time based on a phase velocity formed by the vibration detected by the vibration detecting means; A third deriving means for deriving a phase difference with respect to a reference phase based on the propagation delay time derived by the first deriving means and the propagation delay time derived by the second deriving means. And between the vibration input point of the vibration transmitting member and the vibration detecting means based on the propagation delay time derived by the second deriving means and the phase difference derived by the third deriving means. In a coordinate input device having distance deriving means for deriving a distance and coordinate deriving means for deriving the coordinates of the vibration input point based on the distance derived by the distance deriving means, the third deriving means Constant storage means for storing a plurality of values as constants corresponding to the group velocity used for deriving a phase difference with respect to a reference phase, and the first derivation means or the second
Group velocity selection means for selecting one value from a plurality of values corresponding to the group velocity in the constant storage means based on the derivation result of the group velocity selection means, and the third derivation means selects the group velocity selection means. By using a value corresponding to the group velocity selected by the means, the phase difference with respect to the reference phase is derived.

In the first invention, correction value storage means for storing a propagation delay time of a signal based on the group velocity and the phase velocity from a predetermined point of the vibration transmitting member as a correction value is provided, and the third derivation is provided. The means is based on a difference between the propagation delay time derived by the first and second derivation means and the correction value stored in the correction value storage means.
The distance deriving unit is configured to derive the phase difference, and the vibration is based on the phase difference derived by the third deriving unit and the propagation delay time derived by the second deriving unit. In a configuration for deriving a distance between the input point and the vibration detection means, further, the group velocity selection means,
A plurality of values corresponding to the group velocity in the constant storage means, based on a comparison result of the propagation delay time derived by the first derivation means and the propagation delay time stored in the correction value storage means. It is configured to select one value from.

In order to achieve the above object, the coordinate inputting method of the second invention uses the vibration detecting means provided in the vibration transmitting member for propagating the vibration caused by the contact of the vibration inputting means, and inputs the vibration by the vibration inputting means. Vibration detection processing for detecting the generated vibration, first derivation processing for deriving the propagation delay time of the signal based on the group velocity, which is formed by the vibration detected by the vibration detection processing, and detection by the vibration detection processing A second derivation process for deriving a propagation delay time of a signal based on a phase velocity formed by the generated vibration, and the first derivation process.
Of the propagation delay time derived by the derivation process of
The third derivation process for deriving a phase difference with respect to a reference phase, and the propagation delay time derived by the second derivation process and the third derivation based on the propagation delay time derived by the derivation process Based on the phase difference derived by the process, a distance derivation process for calculating the distance between the vibration input point of the vibration transmission member and the vibration detection means, and based on the distance derived by the distance derivation process, In a coordinate input method including a coordinate derivation process for deriving the coordinates of the vibration input point, a plurality of constants corresponding to the group velocity used for deriving the phase difference with respect to the reference phase in the third derivation process are used. A constant storage means for storing a value is provided, and based on the derivation result of the first derivation processing or the second derivation processing, a plurality of groups corresponding to the group velocities in the constant storage means are provided. After group velocity selection process of selecting one value from, as the third calculation process, using the value corresponding to the group velocity selected in the group velocity selection process,
The phase difference with respect to the reference phase is derived.

In the second invention, correction value storage means for storing a propagation delay time of a signal based on the group velocity and the phase velocity from a predetermined point of the vibration transmitting member as a correction value is provided, and the third derivation is provided. The process derives the phase difference based on the difference between the propagation delay time derived by the first and second derivation processes and the correction value stored in the correction value storage means, and the distance derivation process. Derives the distance between the vibration input point and the vibration detection means based on the phase difference derived in the third derivation process and the propagation delay time derived in the second derivation process. Further, the group velocity selection processing is performed in the constant storage means based on a comparison result of the propagation delay time derived by the first derivation processing and the propagation delay time stored in the correction value storage means. The group velocity It is obtained by a plurality of values corresponding to select a single value.

[0063]

According to the coordinate input device of the first aspect of the invention, the group velocity selecting means determines the group velocity in the constant storing means based on the derivation result of the first deriving means or the second deriving means. One value is selected from a plurality of corresponding values, and the value corresponding to the group velocity selected by the group velocity selecting means is used to derive the phase difference with respect to the reference phase. As a result, a value corresponding to the group velocity used in n calculation can be selected and used based on the approximate position of the vibration input point, and an error in n value calculation due to waveform deformation associated with the transmission distance of the detection signal of the vibration detection means. (Δn) can be suppressed small.

In the first aspect of the invention, the third derivation means is a signal propagation delay time and correction value storage means based on the group velocity and the phase velocity derived by the first and second derivation means. The phase difference is derived on the basis of the difference from the correction value stored in, and the distance deriving means is based on the phase difference derived by the third deriving means and the propagation delay time derived by the second deriving means. Then, the distance between the vibration input point and the vibration detecting means is derived, and the group velocity selecting means further comprises the propagation delay time derived by the first deriving means and the propagation delay time stored in the correction value storing means. 1 from a plurality of values corresponding to the group velocity in the constant storage means based on the result of comparison with
By selecting one of the two values, it is possible to obtain the approximate coordinates of the vibration input point by extremely simple processing, and it is possible to reduce the error in the n-value calculation due to the waveform deformation associated with the transmission distance of the detection signal of the vibration detection means. .

According to the coordinate input method of the second aspect of the present invention having the above structure, one of a plurality of values corresponding to the group velocity in the constant storage means is calculated based on the derivation result of the first derivation process or the second derivation process. After performing the group velocity selection process of selecting one value, the third derivation process uses the value corresponding to the selected group velocity to derive the phase difference with respect to the reference phase. Similar to the first aspect of the invention, it is possible to reduce the error in calculating the n value.

In the second aspect of the invention, the third derivation process is based on the difference between the propagation delay time derived by the first and second derivation processes and the correction value stored in the correction value storage means. The phase difference is derived, and the distance derivation process is performed by the third
The distance between the vibration input point and the vibration detection means is derived based on the phase difference derived in the derivation process of (1) and the propagation delay time derived in the second derivation process. One value is selected from a plurality of values corresponding to the group velocity in the constant storage means, based on the result of comparison between the propagation delay time derived by the derivation process of 1 and the propagation delay time stored in the correction value storage means. By doing so, similar to the above, it is possible to obtain the approximate coordinates of the vibration input point by an extremely simple process, and it is possible to suppress an error in n-value calculation to be small.

[0067]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of an arithmetic control circuit according to the first embodiment of the coordinate input device of the present invention.

The coordinate input device of the present embodiment is a group velocity used in the conventional device shown in FIG. 5 for obtaining a phase difference with respect to a reference phase in, for example, a nonvolatile memory in the microcomputer 31 of the arithmetic control circuit 1. Constant storage means 31a for storing a plurality of values as constants corresponding to the above, and correction value storage means 31b for storing the propagation delay time of a signal based on the group velocity and the phase velocity from a predetermined point of the vibration transmission plate 8 as a correction value. And a microcomputer 3
The ROM of FIG. 1 stores the processing procedure shown in FIG. 2 to be described later, which is referred to as a microcomputer 31 ′ in FIG.
The processing procedure shown in is executed.

That is, as shown in FIG. 2 described above, the configuration itself is such that the operation control circuit 1, the vibrator drive circuit 2, the vibrating pen 3 incorporating the vibrator 4, the vibration sensors 6a to 6d, the vibration isolator 7, Signal waveform detection circuit 9, display drive circuit 1
0 and display 11. Details are as described above and will be omitted.

The processing procedure by the arithmetic control circuit 1 when performing n calculation in this embodiment will be described below with reference to the flowchart of FIG.

First, when the operator designates the coordinates with the vibrating pen 3, the vibration sensors 6a to 6d detect the vibration to obtain the vibration transmission delay times tg 'and tp' (step S11). Obtained vibration transmission delay time tg ', tp'
Of the vibration transmission delay time tg ′ and the correction value storage means 31
The transmission delay time tgz 'at the origin O stored in a is compared (step S12).

In the comparison process of step S12,
In the case of tg '≦ tgz', if the vibration input point is closer to the vibration sensor than the origin O, the rough position of the vibration sensor can be judged. Therefore, 2 corresponding to the group velocity stored in the constant storage means 31a in advance can be used. Of the two constants Vg1 and Vg2, Vg1 having a smaller value is selected.

If tg 'is larger than tgz', it can be determined that the vibration input point is farther from the vibration sensor than the origin O, and therefore, in step S14, the two constants Vg1 and Vg2 stored in advance in the constant storage means 31a are stored. Of these, Vg2 having a large value is selected. Then, using the constant Vg1 or Vg2 corresponding to the selected group velocity, the integer n is calculated by the above equation (3) (step S1).
5). After that, the pen-sensor distance calculation and the pen coordinate calculation described above are performed as in the conventional technique (step S1).
6, step S17).

In the steps S15 to S17, the circuit delay time e according to the transmission delay times tgz 'and tpz' at the origin O stored in the correction value storage means 31a.
It goes without saying that the t and the phase offset toff are deleted. It goes without saying that the above flow is applied to each of the vibration sensors 6a to 6d.

In the above n calculation, as in the prior art,
When a typical Vg '(a value approximately in the middle between Vg1 and Vg2) from the distance between the pen and the sensor to the long distance is used based on the thickness information of the vibration transmission plate 8, as shown in FIG. At a long distance, Δn in the negative direction is generated. This is because when a typical Vg ′ (the inclination of tg of the envelope peak position is a typical Vg ′ for simplification of description) is used as shown in FIG. 13, Vg ′ × Vg ′ is L. This is because a negative error occurs with respect to the actual distance L.

In the present embodiment, by using Vg1 which is slower than Vg 'at a short distance and Vg2 which is faster than Vg' at a long distance, the above error can be reduced.
As shown in FIG. 3, Δn can be made extremely small. Numerically, when a plate wave having a central frequency component of 500 kHz propagates through a plate glass (soda lime glass) having a plate thickness of 2 mm, and a typical group velocity Vg ′ is 3400 m / s, Vg1 and Vg2 are each greater than Vg ′. 20-40m
/ S may be set to minus and plus. The set value may be obtained in advance by experiments or the like.

From the above, the waveform deformation due to the superposition of the reflected waves from the plate end surface, which is another cause of the n jump, the waveform deformation due to the inclination of the vibrating pen or the writing pressure, the circuit delay time due to the environment (temperature, humidity) during use et, phase offset toff
Even if there is a change in Vg, Vp, and λp,
The probability of occurrence of n jumps can be suppressed to an extremely low level.

As described above, in the present embodiment, in order to remove the circuit delay time et and the phase offset toff, the vibration transmission delay time at the origin O, which is measured and stored in advance, and the detected vibration transmission delay. By adding a very simple process of setting Vg by comparing with time, Δn can be suppressed to a small value, and a stable and highly accurate coordinate input device without n jumps can be realized.

Next, a second embodiment will be described.

In the first embodiment, by comparing the vibration transmission time tgz 'at the origin O with the detected vibration transmission time tg', it is determined that the approximate position of the vibration input point is closer or farther than the origin O. However, the approximate position of the vibration input point,
Alternatively, the approximate distance between the pen and the sensor may be calculated, and Vg corresponding to the group velocity may be selected based on the calculation result.

In the present embodiment, the processing procedure by the arithmetic control circuit 1 at the time of calculating the approximate distance between the pen and the sensor and performing n calculation in the case of selecting Vg based on the calculation result is shown in the flowchart of FIG. It will be explained based on. The configuration of the coordinate input device is the same as that of the first embodiment, and the description thereof will be omitted.

First, when the operator designates the coordinates with the vibrating pen 3, the vibration sensors 6a to 6d detect the vibration to obtain the vibration transmission delay times tg 'and tp' (step S21).

Next, with the preset VgO (for example, the representative Vg of the first embodiment may be used), the above (1)
The approximate pen-sensor distance is derived from the equation (step S22). With respect to the derived distance, one Vg is selected from a plurality of Vg set in advance (step S23). For example, when the distance between the pen and the sensor fluctuates between 20 and 270 mm from the relationship between the sensor position and the effective area, the V corresponds to the distance at a pitch of 50 mm.
It suffices to prepare a table in which 5 g is determined. In this case, Vg is set to increase as the pen-sensor distance increases.

Vg corresponding to the selected group velocity
Is used to calculate the integer n by the equation (3) (step S
24). Then, the pen-sensor distance calculation and the pen coordinate calculation are performed as in the prior art (steps S25 and S26).

In steps S15 to S17, the circuit delay time e is calculated according to the transmission delay times tgz 'and tpz' at the origin O stored in the correction value storage means 31b.
It goes without saying that the t and the phase offset toff are deleted. Needless to say, the above flow is applied to each of the sensors 6a to 6d.

Also in the present embodiment, by adding a simple process of calculating the approximate distance between the pen and the sensor and selecting Vg based on the calculation result, Δn can be suppressed to a small value, and n can be skipped. It is possible to realize a stable and highly accurate coordinate input device.

In the present embodiment, the above equation (1) was used to calculate the approximate distance between the pen and the sensor.
It suffices to be able to determine in which position the 270 mm range is divided by the 50 mm pitch, and the accuracy of equation (1) does not pose any problem. Further, the calculation of the approximate distance between the pen and the sensor may be performed by using the expressions (2) and (3). in this case,
Even if n jumps, one wavelength (for example, plate thickness 2 m
m is plate glass (soda lime glass) with center frequency component 5
Phase velocity of 2400 m when a plate wave of 00 kHz propagates
/ S is an error of 1 wavelength = 4.8 mm), and there is no problem in determining the approximate distance.

In the present embodiment, the degree of roughness to obtain the approximate distance between the pen and the sensor, in other words, how many Vg is set is not limited in any way, and any of them may be used. Needless to say.

[0090]

As described above in detail, according to the coordinate input device of the first invention, the third deriving means is suitable for the group velocity used for deriving the phase difference with respect to the reference phase. Based on the derivation result of the first derivation means or the second derivation means, one value is selected from a plurality of values corresponding to the group velocity in the constant storage means based on the derivation result of the constant derivation means for storing a plurality of values as the constant Since the third deriving means uses a value corresponding to the group velocity selected by the group velocity selecting means to derive the phase difference with respect to the reference phase, the vibration input A value corresponding to the group velocity used in n calculation can be selected and used based on the approximate position of the point, and an error (Δn) in n value calculation due to waveform deformation accompanying the transmission distance of the detection signal of the vibration detection means can be reduced. Hold down, fly n Not stable and it is possible to realize a coordinate input apparatus of high accuracy.

In the first invention, the correction value storage means for storing the propagation delay time of the signal based on the group velocity and the phase velocity from the predetermined point of the vibration transmitting member as the correction value is provided, and the third derivation means is In the configuration, the phase difference is derived based on the difference between the propagation delay time of the signal based on the group velocity and the phase velocity derived by the first and second derivation means and the correction value stored in the correction value storage means. At the same time, the distance deriving means calculates the distance between the vibration input point and the vibration detecting means based on the phase difference derived by the third deriving means and the propagation delay time derived by the second deriving means. Further, the group velocity selecting means stores the constant velocity in the constant storage means based on the comparison result of the propagation delay time derived by the first deriving means and the propagation delay time stored in the correction value storage means. The group velocity Since a configuration of selecting one value from multiple values corresponding, it is possible to suppress extremely the simple process it is possible to obtain the outline coordinates of the vibration input point, reduce an error n value calculation.

According to the coordinate input method of the second invention, the third method
In the first derivation process or the second derivation process, a constant storage means for storing a plurality of values as constants corresponding to the group velocity used to derive the phase difference with respect to the reference phase in the derivation process is provided. After performing a group velocity selection process of selecting one value from a plurality of values corresponding to the group velocity in the constant storage means on the basis of the derivation result of, as the third derivation process,
Since the phase difference with respect to the reference phase is derived by using the value corresponding to the selected group velocity, it is possible to suppress the error in n value calculation to be small as in the first aspect of the invention.

In the second invention, the correction value storage means for storing the propagation delay time of the signal based on the group velocity and the phase velocity from the predetermined point of the vibration transmitting member as the correction value is provided, and the third derivation process is performed. , The phase difference is derived based on the difference between the propagation delay time derived by the first and second derivation processes and the correction value stored in the correction value storage means, and the distance derivation process performs the third derivation. The distance between the vibration input point and the vibration detecting means is derived based on the phase difference derived in the processing and the propagation delay time derived in the second derivation processing, and the group velocity selection processing is performed in the first derivation. Based on the result of comparison between the propagation delay time derived by the processing and the propagation delay time stored in the correction value storage means, one value is selected from a plurality of values corresponding to the group velocity in the constant storage means. So, as above, Summary coordinates of the vibration input point by a simple process Te can be obtained, it is possible to minimize the error of the n values calculated.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an arithmetic control circuit according to an embodiment of a coordinate input device of the present invention.

FIG. 2 is a flowchart showing a processing procedure by an arithmetic control circuit when performing n calculation in the first embodiment.

FIG. 3 is a diagram showing an effect of the first embodiment.

FIG. 4 is a flowchart showing a processing procedure by an arithmetic control circuit when performing n calculation in the second embodiment.

FIG. 5 is a block diagram showing a schematic configuration of a conventional ultrasonic type coordinate input device.

FIG. 6 is a configuration diagram of a vibrating pen.

FIG. 7 is a block diagram showing a schematic configuration of an arithmetic control circuit 1.

FIG. 8 is a time chart of signal processing.

FIG. 9 is a block diagram showing a configuration of a signal waveform detection circuit 9 of a conventional coordinate input device.

FIG. 10 is a diagram showing a coordinate system of a coordinate input device.

FIG. 11 is a frequency characteristic diagram of a detection signal and a frequency characteristic diagram of a propagation velocity of a plate wave.

FIG. 12 is an explanatory diagram of waveform deformation according to a vibration transmission distance.

FIG. 13 is an explanatory diagram of tg nonlinearity.

FIG. 14 is a diagram showing a conventional integerization error.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 arithmetic control circuit 2 vibrator drive circuit 3 vibrating pen 4 vibrator 6a to 6d vibration sensor 7 antivibration material 8 vibration transmission plate 9 signal waveform detection circuit 10 display drive circuit 11 display 31 'microcomputer 31a constant storage means 31b correction value Means of storage

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yuichiro Yoshimura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Atsushi Tanaka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Co., Ltd. (72) Inventor Hajime Sato 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (4)

[Claims] 1. A vibration input means for inputting vibration,
A vibration transmission member that propagates the vibration input by the contact of the vibration input unit, a vibration detection unit that is provided on the vibration transmission member and that detects the vibration input by the vibration input unit, and a detection unit that detects the vibration. First deriving means for deriving a propagation delay time of the signal based on the group velocity, which is formed by the generated vibration, and a propagation delay time of the signal based on the phase velocity, which is formed by the vibration detected by the vibration detecting means. Based on the propagation delay time derived by the first derivation means and the propagation delay time derived by the second derivation means, the phase difference with respect to the reference phase is derived. Based on the propagation delay time derived by the second deriving means and the phase difference derived by the third deriving means. Distance deriving means for deriving the distance between the vibration input point of the reaching member and the vibration detecting means, and coordinate deriving means for deriving the coordinates of the vibration input point based on the distance derived by the distance deriving means. A coordinate input device having a constant storage means for storing a plurality of values as a constant corresponding to a group velocity used for deriving a phase difference with respect to a reference phase by the third deriving means; Group velocity selection means for selecting one value from a plurality of values corresponding to the group velocity in the constant storage means based on the derivation means or the derivation result of the second derivation means, and the third derivation means The coordinate input device is configured to derive a phase difference with respect to a reference phase by using a value corresponding to the group velocity selected by the group velocity selecting means. 2. A correction value storage means for storing, as a correction value, a propagation delay time of a signal based on a group velocity and a phase velocity from a predetermined point of the vibration transmission member, the third derivation means includes the third derivation means. The phase difference is derived based on the difference between the propagation delay time of the signal based on the group velocity and the phase velocity derived by the first and second derivation means and the correction value stored in the correction value storage means. At the same time, the distance deriving means is configured to connect the vibration input point and the vibration detecting means based on the phase difference derived by the third deriving means and the propagation delay time derived by the second deriving means. In the configuration, the group velocity selecting means determines the result of comparison between the propagation delay time derived by the first deriving means and the propagation delay time stored in the correction value storage means. Based on ,
The coordinate input device according to claim 1, wherein one value is selected from a plurality of values corresponding to the group velocity in the constant storage means. 3. A vibration detecting process for detecting a vibration input by the vibration inputting device by using a vibration detecting device provided in a vibration transmitting member for propagating a vibration caused by contact of the vibration inputting device, and the vibration detecting process. A first derivation process for deriving a propagation delay time of a signal based on the group velocity, which is formed by the vibration detected by, and a propagation of a signal based on the phase velocity, which is formed by the vibration detected by the vibration detection process. A second derivation process for deriving a delay time, and the first derivation process
Of the propagation delay time derived by the derivation process of
The third derivation process for deriving a phase difference with respect to a reference phase, and the propagation delay time derived by the second derivation process and the third derivation based on the propagation delay time derived by the derivation process Based on the phase difference derived by the process, a distance derivation process for calculating the distance between the vibration input point of the vibration transmission member and the vibration detection means, and based on the distance derived by the distance derivation process, A coordinate inputting method including a coordinate deriving process for deriving the coordinates of a vibration input point, wherein a plurality of values as constants corresponding to the group velocity used for deriving a phase difference with respect to a reference phase in the third deriving process. A constant storage means for storing is stored, and based on the derivation result of the first derivation processing or the second derivation processing, a plurality of groups corresponding to the group velocity in the constant storage means After performing the group velocity selection process of selecting one value from the above, the value corresponding to the selected group velocity in the group velocity selection process is used as the third derivation process, and the phase difference with respect to the reference phase is used. A coordinate input method characterized by deriving. 4. A correction value storage means for storing, as a correction value, a propagation delay time of a signal based on a group velocity and a phase velocity from a predetermined point of the vibration transmitting member, the third derivation process is performed by the third derivation process. The phase difference is derived based on the difference between the propagation delay time of the signal based on the group velocity and the phase velocity derived respectively by the first and second derivation processes and the correction value stored in the correction value storage means, and The distance derivation process is based on the phase difference derived in the third derivation process and the propagation delay time derived in the second derivation process, and the distance between the vibration input point and the vibration detection means. Further, the group velocity selection process is based on a comparison result of the propagation delay time derived by the first derivation process and the propagation delay time stored in the correction value storage means,
4. The coordinate input method according to claim 3, wherein one value is selected from a plurality of values corresponding to the group velocity in the constant storage means.