JPH06332608A - Coordinate input device - Google Patents

Abstract

PURPOSE:To provide the coordinate input device whose precision is high, and also, whose circuit scale is small. CONSTITUTION:Vibration inputted to a vibration transfer plate 8 from a vibration pen 3 is detected by sensors 6a-6d. In an arithmetic and control circuit 1, an arrival time until the vibration is detected by each sensor is measured. In that case, a vibration arrival time to each sensor is compared with the maximum count value determined size of a valid area A of the plate 8 and propagating velocity of the vibration, corrected in accordance with its result, and thereafter, based on a timing for detecting the vibration by the sensor 6a as a reference, difference data of the arrival time related to other sensor is calculated, and a coordinate is determined thereby.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate input device for detecting input vibration and determining coordinates by specifying the position of a vibration source.

[0002]

2. Description of the Related Art Conventionally, in a coordinate input device utilizing ultrasonic vibration, vibration input from a vibrating pen is detected by a plurality of sensors provided on a propagating body, and one of a plurality of sensors on the propagating body is detected. One of the sensors (for example, the first-arrival sensor from the input point) determines the coordinates of the vibrating pen on the propagating body based on the difference data of the arrival delay time with respect to other sensors when the arrival delay time is used as a reference. It was

In the coordinate input device, the coordinate position calculation formula is as follows in the configuration shown in FIG.

The values Δdb to Δdd calculated from the arrival delay time difference data are Δdb = db-da (101) Δdc = dc-da (102) Δdd = dd-da (103)

The point p (x, y) is

[0006]

[Equation 1]

[0007]

[Equation 2] However, the above equation holds when Δdb + Δdd−Δdc ≠ 0 (106).

When Δdb + Δdd−Δdc = 0 (107), x = X / 2 (108) y = (Y ± √A) / 2 (109) A = Δdb ² (1 + X ² / (Y ² − Δdb ² ) (110) or y = Y / 2 (111) x = (X ± √B) / 2 (112) B = Δdd ² (1 + Y ² / (X ² −Δdd ² )) (113) ) Has become.

[0009]

However, in the above-mentioned conventional example, there are cases where a plurality of signals are detected at the same time when the differential data is acquired, and one counter starts,
Only by allocating the stop signal to each signal and measuring the difference, the circuit delay or the group delay time and the phase delay time are reversed by each sensor, which causes an error in the determination of the first-arrival sensor.

Further, simply starting two counters at the same time and counting each of them requires a counter length longer than the repetition period of the signal source, which causes an increase in circuit scale.

Further, in the coordinate position calculation formula of the conventional example,
When Expression (106) is established, Expression (104) and Expression (10)
The result calculated by 5) is the equation (108) and the equation (11).
There is a drawback that an error is likely to occur in the vicinity of 1).

The present invention has been made in view of the above-mentioned conventional example, and an object of the present invention is to provide a coordinate input device with improved accuracy while keeping the circuit scale small.

[0013]

In order to achieve the above object, the coordinate input device of the present invention has the following structure. Input means for inputting vibrations, a vibration transmitting body for transmitting vibrations, a plurality of detecting means for detecting vibrations of the vibration transmitting bodies at mutually different positions, and vibrations input from the input means after being input. Measuring means for measuring the time required until each of the plurality of detecting means is detected, and the required time measured by the measuring means for one of the plurality of detecting means from the required time for each of the other detecting means. Means for calculating a difference value by subtracting, a determination means for comparing each of the difference values with a predetermined value to determine a magnitude relationship, and a correction means for correcting the difference value based on a determination result by the determination means, And a calculation unit that calculates the position at which the vibration is input by the input unit based on the difference value corrected by the correction unit.

[0014]

With the above structure, the vibration input from the input means is detected by the plurality of detecting means provided on the propagating body, and the arrival delay time of one of the plural detecting means on the propagating body is detected. The difference value of the arrival delay time with other detection means when the reference, determines whether or not exceeds a predetermined value,
The difference value is corrected based on the determination result, and the coordinate position is calculated from the value.

[0015]

【Example】

<Arrangement of Device> FIG. 1 shows the structure of a coordinate input device according to an embodiment of the present invention. 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 driving circuit built in the vibrating pen 3, which drives the vibrator 4 in the vibrating pen to vibrate the pen tip 5. 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 vibration generated by the vibrating pen 3 is incident on the vibration transmission plate 8 by designating the area (hereinafter referred to as the effective area) indicated by the solid line A in the figure with the vibrating pen 3, and the incident vibration is measured. The position coordinates of the vibrating pen 3 can be calculated by performing the processing.

In order to prevent (reduce) the transmitted wave from being reflected at the end surface of the vibration transmitting plate 8 and returning to the center of the reflected wave, a vibration isolator 7 is provided on the outer periphery of the vibration transmitting plate 8. The
As shown in FIG. 1, vibration sensors 6a to 6d, such as a piezoelectric element, which convert mechanical vibrations into electric signals are fixed near the inside of the vibration isolator. Reference numeral 9 denotes a signal waveform detection circuit that outputs a signal in which vibration is detected by each of the vibration sensors 6a to 6d to the arithmetic control circuit 1. Reference numeral 11 is a display such as a liquid crystal display capable of displaying in dot units, and is arranged behind the vibration transmission plate. Then, by driving the display drive circuit 10, it is possible to display a dot at a position traced by the vibrating pen 3 and see it through the vibration transmission plate 8 (made of a transparent member).

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 driving the vibrator, with respect to the vibration transmission plate 8,
A mode that vibrates in the vertical direction is selected. Further, by setting the vibration frequency of the vibrator 4 to the resonance frequency including the pen tip 5, it is possible to perform efficient vibration conversion. The elastic wave transmitted to the vibration transmitting plate 8 as described above is a plate wave, and has an advantage that it is less susceptible to scratches and obstacles on the surface of the vibration transmitting plate as compared to surface waves.

<Description of Arithmetic and Control Circuit> In the above-mentioned configuration, the vibrator driving circuit 2 outputs a signal for driving the vibrator 4 in the vibrating pen 3 at every predetermined cycle (for example, every 5 ms). Then, the vibration generated by the vibrating pen 3 propagates on the vibration transmission plate 8 and arrives with a delay depending on the distance to the vibration sensors 6a to 6d.

The signal waveform detection circuit 9 includes the vibration sensors 6a to 6a.
The signal from 6d is detected, and a signal indicating each time difference between the vibration sensor 6a serving as a reference and the vibration arrival timing to 6b to 6d is generated by a waveform detection process described later. This time difference signal for each combination is input, and the difference between the vibration arrival times of the reference vibration sensor, for example, 6a and the other vibration sensors 6b to 6d is measured, and the coordinate position of the vibration pen is calculated. Further, the arithmetic control circuit 1 drives the display drive circuit 10 based on the calculated position information of the vibrating pen 3 to control the display on the display 11, or outputs the coordinate output to an external device by serial or parallel communication. Perform (not shown).

<Arrangement of Arithmetic and Control Circuit> FIG. 2 is a block diagram showing the schematic arrangement of the arithmetic and control circuit 1 of the embodiment. The respective constituent elements and the outline of their operation will be described below.

Reference numeral 21 in the drawing denotes a microcomputer for controlling the arithmetic control circuit 1 and the entire coordinate input device,
It is composed of an internal counter, a ROM storing operation procedures, a RAM used for calculation and the like, a non-volatile memory storing constants and the like. Reference numerals 22a to 23b are counters for measuring the delay time of the vibration sensors 6a to 6d, and in this embodiment, they are composed of four counters for inputting the vibration transmission delay time signals of the reference vibration sensor 6a and the other vibration sensors 6b to 6d. Has been done.

The signal of the vibration arrival delay time of each of the vibration sensors 6a to 6d output from the signal waveform detection circuit 9 is sent to the counter 22a via the detection signal input circuit 25 to the group delay time signal Tga of the vibration sensor 6a and the counter. The group delay time signals Tgb to Tgd of the vibration sensors 6b to 6d are shown at 22b, and the phase delay time signal Tp of the vibration sensor 6a is shown at the counter 23a.
The phase delay signals Tpb to Tpd of the vibration sensors 6b to 6d are input to the counter 23b.

When the judging circuit 26 judges that the signal has been received, it outputs a signal to that effect to the microcomputer 21, and the microcomputer 21 performs a predetermined calculation to determine the coordinates of the vibrating pen 3 on the vibration transmitting plate 8. Calculate the position. Then, by outputting the calculated coordinate position information to the display drive circuit 10 via the I / O port 26, dots can be displayed at the corresponding positions on the display 11. 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 26.

<Operation of Arithmetic Control Circuit> Next, the operation of the arithmetic control circuit 1 will be described with reference to FIGS.

3 to 5 are flowcharts for obtaining the vibration arrival delay time difference data of the arithmetic control circuit 1.
FIG. 6 is a timing chart showing each signal according to the flowcharts of FIGS. In FIG. 6, a clear signal 40 and a start signal 41 are signals from the microcomputer 21 to the counter group, and are signals for instructing clearing of the counter and starting of the counter, respectively. Ach (A channel) Tp signal 42 and Bch
The (B channel) Tp signal 43 is a signal corresponding to a signal 78 or 79 in FIG. 9 described later. In FIG. 6, since the purpose is to explain the procedure for acquiring the difference data for each sensor, the signal relating to the group delay is omitted.

BchSEL0 signal 45 and BchSEL
The 1 signal 46 is a signal for selecting the sensor of channel B.

3 to 5, step 311 is for switching between Ach and Bch of the signals 42 and 43 of FIG. 4, and the signal of the reference sensor 6a is input to Ach and the signal of the sensor 6b is input to Bch. To set. Bc
h can switch sensors by signals 45,46. In step 312, all the counters are reset by the reset signal CLEAR issued by the microcomputer 21, and Ach and Bc are reset by the start signal START.
4 counters corresponding to h are started simultaneously.
In step 313, the determination circuit 24 determines the presence / absence of a signal, and if the signal is not input, for example, in step 316, 1.5 msec is waited, and then in step 317, the vibration pen 3 transmits the vibration to the vibration transmission plate 8. Judge that it has not.

In step 314, the first signal may not be measured by the counters 22a to 23b due to the influence of reverberation or the like, so that the data is stored in the memory to improve the reliability of the data. No (Fig. 6, timing t
1) In step 320, the counter is cleared and restarted. After that, the second signal of the Ach reference sensor 6a is determined in step 321, the counter values of the counter 22a and the counter 23a stopped thereby are stored in the memory, and the counter 22b and the counter stopped by the signal of the sensor 6b are stored. The counter value of 23b is stored in the memory. With the counter values Tga, Tgb, Tpa, and Tpb obtained by the microcomputer, step 32 is performed.
2, ΔTgb = Tgb-Tga and ΔTpb = Tpb-T
pa is calculated and stored in the memory in step 323.

Next, in step 330, the Bch sensor 6c is detected.
And the same processing as above is performed. In this case,
In step 331, dereverberation is performed by inserting a waiting time of 500 microseconds, and the first pulse is used as it is as a signal for a signal for distance calculation.

Similarly, in step 340, the Bch is switched to the sensor 6d and the same processing as above is performed.

As described above, the microcomputer 2
If the difference data calculated by 1 is obtained for each sensor of the other sensors 6b to 6d with respect to the reference sensor 6a,
Coordinates are calculated from the difference data. The above processing is executed by the microcomputer 21 as an interrupt.

The counters 22a to 23b are finite counters, and the maximum counter value thereof is in accordance with the maximum difference data determined by the propagation speed at which the ultrasonic vibration of the vibrating pen 3 propagates through the vibration transmission plate 8 and the input area. Decided. In the present embodiment, the maximum counter value is twice or more the maximum difference data.

Steps 322 and 33 in FIGS. 3, 4 and 5
The differential data obtained in 4.344 is processed as in steps 52 to 55 of the flowchart of FIG. 7 and stored in the memory of the microcomputer 21.

In FIG. 7, in the judgment processing of step 53, it is judged whether or not the maximum difference data is smaller than the obtained difference data, and if smaller, the difference data obtained in step 55 is corrected. That is, if the difference between the counter time-measured values of the reference sensor A and the sensor B in FIG. 8 is left as it is, when the maximum value of the counter is exceeded, the difference data to be acquired will be different from the actual difference data. When the maximum difference data is smaller than the obtained difference data, the difference data is corrected as follows to obtain correct difference data. In FIG. 8, the acquired difference data is ΔA
B, ΔAC, ΔAD, and these values are compared with the maximum difference data. If it is larger than the maximum difference data, it is considered that one counter exceeds the maximum value MAX and makes one round. Therefore, the smaller counter value is MAX.
Is added.

In FIG. 8, assuming that the maximum counter value ≧ 2 × the maximum difference data value, | ΔAB | = | b−a |, and if this is larger than the maximum difference data value, it is corrected. After the correction, | ΔAB | = | (b + MAX) −a | | ΔAC | = | c−a | | ΔAD | = | d−a | Note that MAX is the maximum counter value.

<Description of Vibration Propagation Time Detection (FIGS. 9 and 1)
0)> Hereinafter, the principle of measuring the vibration arrival time to the vibration detection sensors 6a to 6d will be described.

FIG. 9 is a diagram for explaining a detection waveform input to the vibration waveform detection circuit 9 and a vibration transmission time measuring process based on the detection waveform. Hereinafter, the vibration detection sensors 6a and 6a
The case of detecting the difference in b will be described, but the same applies to the other vibration detection sensors 6c and 6d. The drive signal 71 is applied from the vibrator drive circuit 2 to the vibrator 4 in a cycle that is not completely synchronized with the signal waveform detection circuit 9. The ultrasonic vibration transmitted from the vibrating pen 3 to the vibration transmission plate 8 by the signal 71 is detected by the vibration sensor 6a after a signal is given for a time tga corresponding to the distance to the vibration sensor 6a.

The signal indicated by 72 in the figure shows the signal waveform detected by the vibration sensor 6a. Since the vibration used in this embodiment is a plate wave, the envelope 721 and the phase 722 of the detected waveform with respect to the propagation distance in the vibration transmission plate 8 are used.
During vibration transmission, the relationship of changes according to the transmission distance. Here, the traveling speed of the envelope 721, that is, the group speed is Vg, and the phase speed of the phase 722 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 721, its speed is Vg, and when a point on a certain specific waveform, for example, a zero cross point of the twice differentiated waveform 723 of the envelope 721, that is, an inflection point of the envelope waveform is detected. , The distance between the vibration pen 3 and the vibration sensor 6a is given by da = Vg · tga (1) with the vibration transmission time being tga. This formula relates to one of the vibration sensors 6a, but the other three vibration sensors 6b are represented by the same formula.
The distance between 6d and the vibrating pen 3 can be similarly expressed. The distance difference Δdb between the distance da between the vibration sensor 6a and the vibration pen 3 and the distance db between the vibration pen 6b and the pen 3 is the vibration arrival timing 73 (t) for the sensor 6b, which is also detected.
gb), that is, the vibration transmission time 731 (Δtg
From b), it is given by the following equation.

Δdb = Vgtgb-Vgtga = VgΔtgb (2) Further, in order to determine coordinates with higher precision, processing based on detection of a phase signal is performed. A specific detection point of the phase waveform signal 722, for example, a predetermined signal level 7 from vibration application
If the time to the zero cross point after 4 is tpa (obtained by generating a window signal 78 of a predetermined width with respect to the first rising point of the signal 77 after comparison and comparing it with the phase signal 722), the vibration sensor And the distance between the vibrating pen is: da = na · λp + Vp · tpa (3) Here, λp is the wavelength of the elastic wave, and na is an integer. In this case as well, the distance difference Δdb between the sensors 6a and 6b and the difference Δt between the zero cross point tpb of the sensor 6b which is similarly detected.
When expressed by pb, Δdb = nb · λp + Vp · tpb− (na · λp + Vp · tpa) = (nb−na) · λp + Vp · (tpb−tpa) = nb ′ · λp + Vp · Δtpb (4) nb 'has an integer value like nb and na.

From the above equations (2) and (4), the above integer n
b ′ is represented as nb ′ = int [(Vg · Δtgb−Vp · Δtpb) / λp + 1 / N] (5).

Here, N is a real number other than "0", and an appropriate value is used. For example, if N = 2, then nb 'can be determined if there is a variation such as tg within ± 1/2 wavelength. By substituting the determined nb ′ into the equation (4), the difference Δdb between the distance between the vibrating pen 3 and the vibration sensor 6a and the distance between the pen 3 and the sensor 6b can be accurately measured. it can. Signals 731 and 79 for measuring the difference Δtg and Δtp between the two vibration transmission times described above.
1 is generated by the signal waveform detection circuit 9,
This signal waveform detection circuit 9 is constructed as shown in FIG.

FIG. 10 is a block diagram showing a part of the configuration of the signal waveform detection circuit 9 of the embodiment. FIG. 10 shows a portion for detecting the arrival delay time differences Δtgb, Δtpa between the vibration sensors 6a and 6b, and the signal waveform detection circuit 9 includes the same circuit components for 6a and 6c and 6a and 6d. . In FIG. 10, the output signals of the vibration sensors 6a and 6b are amplified by the preamplifier circuit 81 to a predetermined level. The bandpass filter 811 removes extra frequency components of the detected signal from the amplified signal, and the amplified signal is input to an envelope detection circuit 82 including, for example, an absolute value circuit and a low-pass filter. Only is taken out. The timing of the envelope inflection point is detected by the envelope inflection point detection circuit 83. The output of the inflection point detection circuit 83 is a signal Δtg (signal 841 in FIG. 8) which is an envelope delay time detection difference signal between the two sensors formed by a Δtg signal detection circuit 84 composed of a mono-multivibrator and the like. Input to the circuit 1.

On the other hand, reference numeral 85 is a signal detection circuit, which first forms a pulse signal 77 of a portion of the signal waveform 72 detected by the vibration sensor 6a that exceeds a threshold signal 76 of a predetermined level. A monostable multivibrator 86 opens the gate signal 74 of a predetermined time width triggered by the first rising edge of the pulse signal 77. Reference numeral 87 denotes a Δtp signal detection circuit, which detects the first rising zero-cross point of the phase signal 722 while the gate signal 74 is open, and similarly inputs the signal detected by the vibration sensor 6b, the two sensors are connected. Therefore, the phase delay time difference signal Δtp791 of is supplied to the arithmetic control circuit 1. The circuit described above is for the vibration sensors 6a and 6b, and the same circuit is provided for the other two combinations of vibration sensors.

<Explanation of coordinate position calculation (FIGS. 11 and 12)
> Next, the principle of actually detecting the coordinate position on the vibration transmission plate 8 by the 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 vibration pen 3 to the positions of the respective vibration sensors 6a to 6d are obtained based on the principle described above. Then, the distance difference Δdb to dd between the distance da between the sensor 6a and the pen 3 and the distance db to dd between the other sensor and the pen 3 can be obtained. Further, the arithmetic control circuit 1 can obtain the coordinates (x, y) of the position P of the vibrating pen 3 from the Pythagorean theorem based on the linear distance differences da to dd as follows.

First, the calculated Δdb to Δdd are expressed as follows: db = Δdb + da (6) dc = Δdc + da (7) dd = Δdd + da (8)

Da ² = x ² + y ² (9) db ² = (Δdb + da) ² = x ² + (Y−y) ² (10) dc ² = (Δdc + da) ² = (X−x) ² + to become ^{(Y-y) 2 ... (} 11) dd 2 = (△ dd + da) 2 = (X-x) 2 + y 2 ... (12). Here, X and Y are vibration sensors 6a and 6 respectively.
The distance between b and the distance between the vibration sensors 6c and 6d.

Next, (10)-(9), (11)-(1
2) from ^{△ db 2 + 2da · △ db} = Y 2 -2Y · y ... (13) △ dc 2 - △ dd 2 + 2da · (△ dc- △ dd) = Y 2 -2Y · y ... (14) , and the The following equation is obtained by taking the difference between the two equations and obtaining da.

Da = − (db ² + Δdd ² −Δdc ² ) / 2 (Δdd + Δdb−Δdc) (15) This expression holds when the denominator on the right side is not zero, and How to solve the time will be described later. Equation (15)
Substituting into (14), y is obtained as in the following equation.

Y = Y / 2−Δdb ² / 2Y + Δdb · (Δdb ² + Δdd ² −Δdc ² ) / (Δdd + Δdb−Δdc) / 2Y (16) By the same method When x is obtained, x = X / 2−Δdd ² / 2X + Δdd · (Δdb ² + Δdd ² −Δdc ² ) / (Δdd + Δdb−Δdc) / 2X (17) . However, (17) is also satisfied when Δdd + Δdb−Δdc ≠ 0 (18).

Now, the case where the condition of the expression (18) is not satisfied will be examined. Substituting the equations (6) to (8), when the right side is 0, it means that dd + db = dc + da (19), which is when x = X / 2 or y = Y / 2, and da = Dd and db = dc or da = db and dc = dd. In reality, since the signal waveform detection circuit 9 has the time resolution, it takes a zero value with a certain width (≈).

When it is determined that the equation (18) is not satisfied, the subroutine is skipped in the coordinate calculation process, and although it is slightly complicated, a quadratic equation of x or y is set up and solved. First, when x = X / 2, (at this time, Δdb
= (Δdc) (9) to (12) are represented by the following two equations.

[0054] ^{da 2 = X 2/4 +} y 2 ... (20) (△ db + da) 2 = X 2/4 + (Y-y) 2 ... (21) (21) - a da obtained from (20) (20 ), Y is calculated as follows.

Y = (Y ± sqrt (A)) / 2 (22) where A = Δdb ² · (1 + X ² / (Y ² −Δdb ² )) (23) (22) Is “-” when Δdb> 0, and Δdb <0
It is "+" when. "Sqrt (X)" is a function that gives the square root of X.

Similarly, when y = Y / 2, x is obtained as follows.

X = (X ± sqrt (B)) / 2 (24) Here, B = Δdd ² · (1 + Y ² / (X ² −Δdd ² )) (25) where (24) Sign is "-" when Δdd> 0, and Δd
It is "+" when d <0.

However, in the vicinity of y = Y / 2, Δd
Since the values of b and Δdb + Δdd−Δdc are close to 0, the formula (1
Since the second and third terms in 6) are almost 0, the y-coordinate is accurate, but the x-coordinate is y = Y /
In the vicinity of 2, the error of the timing data of Δdd has a great influence on the equation (17), so that the accuracy is low.

Similarly, in the vicinity of x = X / 2, Δdd and Δdb
Since the value of + Δdd-Δdc is close to 0, the second term and the third term of the equation (17) are almost 0, so that the x coordinate is accurate, but the y coordinate is x = X. In the vicinity of / 2, the error of the timing data of Δdb has a great influence on the equation (16), so that the accuracy is poor.

Therefore, y is accurate in the vicinity of y = Y / 2.
After obtaining the coordinates, the x coordinate is obtained from the y coordinates. Similarly, in the vicinity of x = X / 2, an accurate x coordinate is obtained, and then ay coordinate is obtained from the x coordinate.

Therefore, the input area is divided into four areas as shown in FIG. Each area can be divided under the following conditions.

Area 1: Δdb> 0 AND Δdc> 0
AND Δdb <Δdd Area 2: Δdd <0 AND Δdc <0 AND Δ
db <Δdd area 3: Δdb <0 AND Δdc <0 AND Δ
db> Δdd Area 4: Δdd> 0 AND Δdc> 0 AND Δ
db> Δdd In the regions 1 and 3, the x coordinate is calculated using the equation (17).

The y coordinate is obtained by substituting equation (17) into equation (10) as in the following equation.

Y = Y / 2 ± (Δdb × sqrt (A)) / 2 (26) where A = 4x ² / (Y ² −Δdb ² ) +1 (27) Equation (26) The code of the second term is y <Y / 2, Δdb> 0 to “−” in the region 1, y> Y / 2, Δdb <0 to “−” in the region 1, and y in the regions 2 and 4 similarly. The coordinates are calculated using equation (16).

The x coordinate is obtained by substituting the equation (16) into the equation (12) as in the following equation.

X = X / 2 ± (Δdd × sqrt (B)) / 2 (28) Here, B = 4y ² / (X ² −Δdd ² ) +1 (29) Equation (28) The sign of the second term is "-" in the area 2 from x <X / 2, Δdd> 0, and "-" in the area 4 from x> X / 2 and Δdd <0.

FIG. 11 is a flowchart of the above coordinate calculation.
Shown in.

In this way, the position coordinates of the vibrating pen 3 can be detected in real time.

As described above, the coordinates can be directly obtained in real time from the obtained difference signal of the vibration arrival time between the sensors, and the time for the vibration to propagate inside the pen (the offset amount of the arrival delay time) is Since it is ignored by being canceled out by the two sensors, it is not affected by the temperature change of the vibration transmission time inside the pen (especially the pen tip), so there is no erroneous input due to environmental change or accuracy deterioration. Is obtained. Further, since the vibration input by the vibration input pen can be performed asynchronously with the main body of the coordinate input device, the vibration input pen can be made cordless.

In this embodiment, the vibrating pen 3 is a cordless pen which is not connected to the main body by a cord, but it goes without saying that a constitution may be adopted in which a cord is connected and a drive signal is transmitted from the main body. .

The reference vibration sensor is the sensor 6a.
Of course, the desired sensor on the vibration transmission plate may be used as a reference to measure the difference in vibration arrival time at another sensor, and the coordinates may be calculated based on the measured value.

[0072]

Other Embodiments The construction of this embodiment is the same as that of the previous embodiment in the construction of the entire coordinate input device and the construction of the vibrating pen. The propagation velocity as a characteristic of the plate wave used in the coordinate input device of the present invention depends on the product of the frequency and the plate thickness, and the propagation velocity and the frequency also vary due to variations in the sensor and the circuit.
In the previous embodiment, the vibration propagation time is expressed by the following equations (1) to (5) for obtaining the distance from the input point of the vibrating pen to the vibration sensor. The average value of the four sensors is used for the calculation, but in the present embodiment, only the constants of any one of the reference sensor and the other sensor corresponding to the delay time difference data among the four sensors are obtained. Coordinates are calculated by using the average value. The propagation velocity as a characteristic of the plate wave used in the coordinate input device of the present invention depends on the product of the frequency and the plate thickness, and the propagation velocity and the frequency also vary due to variations in the sensor and the circuit.

That is, when the reference sensor 6a and the sensor 6b correspond to the channel of the counter for obtaining the delay time difference data, the average values of the constants of the two sensors are the wavelength λpb, the group velocity Vgb, and the phase velocity Vpb. Then, the distance difference Δdb between the distance da between the vibration pen 3 and the vibration sensor 6a and the distance db between the vibration pen 3 and the vibration sensor 6b is Δdb = when the group delay times of the vibration transmission time are tga and tgb, respectively. db−da = Vgb · (tgb−tga) = Vgb · Δtgb (31)

When further processing based on the phase signal is carried out, Δdb = nbλpb + Vpb (tpb-tpa) = nbλpb + VpbΔtpb (32) Here, nb has an integer value.

From the above (31) and (32), the integer nb is expressed as nb = int [(Vgb · Δtgb-Vgb · Δtgb) / λgb + 1 / N] (33). Here, N is the same as N shown in the first embodiment.

By substituting nb obtained above into (32), Δdb and Δdd can be similarly obtained in the case where the vibration sensors 6c and 6d can accurately obtain Δdb.
Is the average value of the constants of the sensors 6a and 6c and the sensors 6a and 6
It can be obtained by using the average value of the constants of d.

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

[0078]

As described above, the coordinate input device of the present invention has the effect of improving accuracy while keeping the circuit scale small.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of a coordinate input device.

FIG. 2 is a block diagram showing a configuration of an arithmetic control circuit.

FIG. 3 is a flowchart of data processing.

FIG. 4 is a flowchart of data processing.

FIG. 5 is a flowchart of data processing.

FIG. 6 is a timing chart of data processing.

7 is a flowchart of only a process of correcting data in the flowchart of FIG.

FIG. 8 is an explanatory diagram of a data correction method.

FIG. 9 is a timing chart of signal processing.

FIG. 10 is a block diagram showing a configuration of a signal waveform detection circuit.

FIG. 11 is an explanatory diagram for calculating a coordinate position.

FIG. 12 is an explanatory diagram for calculating coordinate positions when dividing FIG. 9 into regions.

FIG. 13 is a flowchart of coordinate calculation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Arithmetic control circuit, 2 ... Oscillator drive circuit, 3 ... Vibration pen, 4 ... Oscillator, 5 ... Pen tip, 6 ... Vibration sensor, 7 ... Antivibration material, 8 ... Vibration transmission plate, 9 ... Signal waveform detection Circuit, 10 ... Display drive circuit, 11 ... Display.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuyuki Kobayashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Yuichiro Yoshimura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (72) Inventor Ryozo Yanagisawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (4)

[Claims] 1. An input unit for inputting vibration, a vibration transmitting body for transmitting the vibration, a plurality of detecting units for detecting the vibration of the vibration transmitting unit at mutually different positions, and a vibration input from the input unit. Measuring means for measuring the time required from the input to the detection by each of the plurality of detecting means, and the necessary time measured by the measuring means for one of the plurality of detecting means, and the other detecting means respectively. For calculating a difference value by subtracting the difference value from the required time, determining means for comparing the difference values with a predetermined value to determine the magnitude relationship, and correcting the difference value based on the determination result by the determining means. A coordinate input device, and a calculating device for calculating a position where the vibration is input by the input device based on the difference value corrected by the correcting device. . 2. The predetermined value is a maximum difference counter value that is determined according to a propagation speed of vibration input by the input means and a size of the vibration transfer body. Coordinate input device. 3. The coordinate input device according to claim 1, wherein the measuring unit measures each of a group delay time and a phase delay time of vibration. 4. The coordinate input device according to claim 1, wherein the calculating means has means for determining an area where vibration is input, and the coordinates are calculated for each of the areas by a different procedure.