JP3109825B2 - Coordinate input device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention detects a vibration input from a coordinate input device, particularly a vibration pen, by a plurality of vibration sensors provided on a vibration transmission plate, and transmits the vibration of the vibration pen. The present invention relates to a coordinate input device for detecting coordinates on a board and a method therefor.

[Conventional technology]

In the coordinate detection method as described above, since the configuration of the vibration transmission plate constituting the input tablet is simple, and a transparent material can be used as the vibration transmission plate, the vibration transmission plate can be disposed on a display, a document, or the like. There are advantages such as.

In this type of coordinate input device, the input vibration from the vibration pen is detected by a plurality of vibration sensors provided on the vibration transmission plate. However, the influence of the phase delay when transmitting the vibration on the vibration transmission plate, Unless the influence of the circuit delay time is corrected, a correct coordinate value cannot be detected. The circuit delay includes not only an electric circuit but also a delay inherent in a circuit that mechanically transmits vibration between the vibration pen and the vibration transmission plate.

In order to obtain accurate coordinate values of input points without being affected by the influence of the phase delay and the delay of the circuit, the present applicant proposed a coordinate input device described below (Japanese Patent Laid-Open No. 01-237712).
No.).

That is, in a coordinate input device that detects vibrations input from the vibration pen by a plurality of vibration sensors provided on the vibration transmission plate to detect coordinates of the vibration pen on the vibration transmission plate, Means for storing, as a correction value, a vibration transmission time of the vibration input from the input point to each of the vibration sensors and a coordinate of the arbitrary input point, and a vibration from the coordinate input point by the vibration pen to each of the vibration sensors. The transmission time is measured, the vibration transmission time correction value stored in the storage means is subtracted from the measured value, and the vibration transmission time corresponding to the distance from the arbitrary input point to the coordinate input point is calculated. And a control unit for performing a coordinate calculation based on the coordinate values of the stored arbitrary input points.

 The operation of the coordinate input device having the above configuration will be described.

FIG. 10 shows the time t on the horizontal axis, the vibration transmission distance from the input point to the vibration sensor on the vertical axis, a group delay time tg in which the envelope of the vibration waveform advances over a certain distance, and the phase in which the phase of the waveform advances This shows a change in the delay time tp.

As shown, the circuit delay time et is always included even at the distance 0, and the curve (straight line) of each delay time is offset to the right in the graph. Further, the phase waveform produces a regular phase delay as shown according to the wavelength, the distance 0 on the group delay time tg and phase delay time difference t _o f, i.e. offset of the phase time of the impact of circuit delay It changes with.

However, according to the above configuration, the vibration transmission time from the arbitrary input point to each vibration sensor and the vibration transmission time from the input point to each vibration sensor similarly include the circuit delay time and the phase offset time. Therefore, by subtracting these, the vibration transmission time from which the circuit delay time and the phase offset time have been removed can be calculated. Since this vibration transmission time is equivalent to the distance from an arbitrary point measured from the position of the vibration sensor to the coordinate input point, if the coordinate calculation is performed based on this vibration transmission time, the influence of the circuit delay time and the phase offset time is not affected. Accurate coordinate values can be obtained.

Here, in order to clarify the problem to be solved by the present invention, a conventional coordinate calculation method will be described.

FIG. 7 illustrates the process of measuring the vibration transmission time. In FIG. 7, reference numeral 41 denotes a drive signal pulse applied to the vibration pen. The ultrasonic vibration transmitted to the vibration transmission plate from the vibration pen driven by such a waveform passes through the vibration transmission plate and is detected by the vibration sensor.

Time tg according to the distance to the vibration sensor in the vibration transmission plate
, The vibration reaches the vibration sensor. Reference numeral 42 in FIG. 7 indicates a signal waveform detected by the vibration sensor. The plate wave used in this embodiment is a dispersive wave, so that the relationship between the envelope 421 and the phase 422 of the detected waveform changes according to the vibration transmission distance.

Here, the speed at which the envelope advances is referred to as group speed Vg, and the phase speed is referred to as Vp. From the difference between the group velocity and the phase velocity, the distance between the vibration pen and the vibration sensor can be detected.

For example, when a peak is detected as indicated by reference numeral 43 in FIG. 7, the distance d between the vibrating pen and the vibration sensor is represented by d = Vg · tg (1) where tg is the vibration transmission time. However, the same formula can be used to indicate the distance between the other two vibration sensors and the vibration pen.

Further, in order to determine coordinate values with higher accuracy, processing based on the detection of the phase signal is performed. Phase waveform 42 in FIG.
If the time from the application of the two specific detection points, for example, the application of the vibration to the zero-crossing point after passing the peak is tp, the distance between the vibration sensor and the vibration pen is d = n · λp + Vp · tp (2). Here, λp is the wavelength of the elastic wave, and n is an integer.

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

The distance between the vibration pen and the vibration sensor can be measured by substituting n obtained as described above into Expression (2).

Now, as shown in FIG. 9, when three vibration sensors are arranged at the corners of the vibration transmission plate at positions S1 to S3, the respective vibrations are moved from the position P of the vibration pen by the processing described with reference to FIG. The linear distances d1 to d3 to the position of the sensor can be obtained. Further, the linear distances d1 to d3 are calculated by the arithmetic and control circuit 1.
The coordinates (x, y) of the position P of the vibrating pen can be obtained from the three-square theorem based on the following equation.

x = X / 2 + (d1 + d2) (d1-d2) / 2X (4) y = Y / 2 + (d1 + d3) (d1-d3) / 2Y (5) where X and Y are the positions of S2 and S3. This is the distance along the X and Y axes between the vibration sensor and the sensor at the origin (position S1).

As described above, the position coordinates of the vibration pen can be detected.

Next, in the calculation of the pen-sensor distance and coordinate determination described above, the circuit delay time et and the phase offset time
correction processing will be described in order to remove the influence of t _o f.

Vibration transmission time to be detected includes a circuit delay time et and phase offset time t _o f. The errors caused by these always include the same amount when vibration is transmitted from the vibration pen to the vibration transmission plate and the vibration sensor.

That is, the point Z whose distance from each vibration sensor is known
, The true vibration transmission time for one of the vibration sensors is t
g ₀ , tg ₀ , the known distance is R _o , the true transmission time to the sensor at the input point P is tg, tp, and the distance between the point P to be determined and the sensor is d, R = n _{o · λp + Vp · (tp} 0 -et-t o f) ... (6) n o = [{Vg · (tg 0 -et) -Vp · (tp 0 -et-t o f)} / λp + 1 / n] ... (7) d = n · λp + Vp · (tp-et-t o f) ... (8) n = [{Vg · (tg-et) -Vp · (tp-et-t o f)} / λp + 1 / n] ... (9) Therefore, d = R + (n- n o) λp + Vp · (tp-tp 0) ... (10) n = n o + [{Vg (tg-tg 0) -Vp (tp-tp _{0) / λp} + 1 /} n] ... (11) where by appropriately setting the n ie n _o at a distance R to the one of the vibration sensors from the position of the mark 8a, n is determined, and further d Can be requested.

[Problems to be solved by the invention]

However, in the above-mentioned conventional example, there is a drawback that accuracy is lowered due to displacement of the vibration sensor due to processing variations of various components constituting the coordinate input device.

The reduction in accuracy due to the displacement of the vibration sensor will be described in detail. FIG. 2 shows the positional relationship between the sensor and the pen. In the figure, the desired point of the sensor is S ₁ (0,0) The actual position of the sensor is S ′ The input point of _one pen is P _[1] (x, y) ▼ = d ₁ , ▼ = d ' ₁ to the _{d '1 = d 1 + Δd} 1 ... (12) Δd 1 by the above formula but is of course S' are those that occur _{because one} does not match the S _1.

In the configuration of FIG. 9, the following equation equivalent to the equation (12) is obtained for each sensor.

d ′ ₂ = d ₂ + Δd ₂ (13) d ′ ₃ = d ₃ + Δd ₃ (14) d ′ ₁ obtained from the above equations (12), (13) and (14),
d ′ ₂ and d ′ ₃ are substituted for d ₁ , d ₂ and d ₃ in the equations (4) and (5). If the coordinates of the calculated point P ₁ are (x ′, y ′) Assuming that the last terms on the right side of the above two equations are Δx and Δy, respectively, x ′ = x + Δy (17) y ′ = y + Δy (18) That is, the coordinates of the point P calculated by the coordinate calculation depend on the displacement of the sensor. Includes errors Δx and Δy. That is, the accuracy is reduced by the displacement of the sensor.

[Means (and action) for solving the problem]

According to the present invention, a vibration transmission plate for transmitting vibration, a plurality of vibration sensors provided on the vibration transmission plate, and a vibration transmission time from an input point to each of the vibration sensors are measured. In a coordinate input device having input point coordinate calculation means for calculating a coordinate value of a point, the coordinate value is defined,
From the absolute coordinate system set on the vibration transmission plate and the vibration transmission time from two or more input points whose coordinate values are known in the absolute coordinate system to each of the vibration sensors, the respective vibrations in the absolute coordinate system are obtained. A sensor position coordinate calculating means for calculating a coordinate value of the sensor position; a position coordinate value of each vibration sensor calculated by the sensor position coordinate calculating means; and input of at least one point used in the sensor position coordinate calculation By providing a calculating means for calculating the coordinate value of the input point based on the coordinate value and the transmission time, it is possible to obtain an accurate coordinate value of the input point without a decrease in accuracy due to a displacement of the vibration sensor. it can.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 4 shows the structure of an information input / output device employing the present invention. The information input / output device shown in FIG. 4 allows an input tablet made of a vibration transmission plate 8 to perform coordinate input by a vibrating pen 3, and a display 11 'made of a CRT arranged on the input tablet in accordance with the input coordinate information. To display the input image.

The reference numeral 8 in the drawing denotes a vibration transmission plate made of acrylic, glass plate or the like, which transmits vibration transmitted from the vibration pen 3 to three vibration sensors 6 provided at the corners. In the present embodiment, the coordinates of the vibration pen 3 on the vibration transmission plate 8 are detected by measuring the transmission time of the ultrasonic vibration transmitted from the vibration pen 3 to the vibration sensor 6 via the vibration transmission plate 8.

The vibration transmitting plate 8 is supported by an anti-reflection member 7 made of silicon rubber or the like in order to prevent the vibration transmitted from the vibration pen 3 from being reflected at the peripheral portion and returning to the central portion. ing.

The vibration transmission plate 8 is arranged on a display 11 'capable of displaying dots, such as a CRT (or a liquid crystal display), and performs dot display at a position traced by the vibration pen 3. That is, a dot is displayed at a position on the display 11 'corresponding to the detected coordinates of the vibrating pen 3, and an image composed of elements such as points and lines input by the vibrating pen 3 is written as if on paper. Appears after the trajectory of the vibrating pen.

Further, according to such a configuration, a menu is displayed on the display 11 ', and the menu item is selected by a vibrating pen, or an input method such as displaying a prompt and bringing the vibrating pen 3 into contact with a predetermined position. Can also be used.

Further, marks 8a, 8b, 8c are provided at predetermined positions (positions are completely arbitrary) on the input surface of the vibration transmission plate 8.
In the present embodiment, the coordinates of the marks 8a, 8b and 8c are stored in advance in a ROM or the like, a vibration input is performed by the vibration pen 3, and the time required for transmitting vibration to each vibration sensor 6 is measured. It is used for correcting the transmission time and calculating the position coordinates of the vibration sensor 6. The correction method and the calculation of the position coordinates of the vibration sensor 6 will be described later in detail.

The vibration pen 3 that inputs ultrasonic vibration to the vibration transmission plate 8
A vibrator 4 including a piezoelectric element or the like is provided therein, and the ultrasonic vibration generated by the vibrator 4 is transmitted to a vibration transmission plate 8 via a horn portion 5 having a sharp tip.

FIG. 5 shows the structure of the vibration pen 3. Vibrating pen 3
Is driven by the vibrator drive circuit 2. The drive signal of the vibrator 4 is supplied as a low-level pulse signal from the arithmetic and control circuit 1 in FIG. 1, and is amplified at a predetermined gain by the vibrator drive circuit 2 capable of low impedance driving. Is applied to

The electric drive signal is converted into mechanical ultrasonic vibration by the vibrator 4 and transmitted to the diaphragm 8 via the horn 5.

The vibration frequency of the vibrator 4 is selected to a value that can generate a plate wave on the vibration transmission plate 8 made of acrylic, glass, or the like. Further, at the time of driving the vibrator, the fifth
A vibration mode in which the vibrator 4 mainly vibrates in the vertical direction in the figure is selected. Further, by setting the vibration frequency of the vibrator 4 to the resonance frequency of the vibrator 4, efficient vibration conversion is possible.

The elastic wave transmitted to the vibration transmission plate 8 as described above is a plate wave, and has an advantage that the surface of the vibration transmission plate 8 is less susceptible to scratches, obstacles, and the like than surface waves.

Again, in FIG. 4, the vibration sensor 6 provided at the corner of the vibration transmission plate 8 is also constituted by a mechanical to electrical conversion element such as a piezoelectric element. The output signals of each of the three vibration sensors 6 are input to a waveform detection circuit 9, and the arrival timing of the vibration at each sensor is detected by a waveform detection process described later. This detection timing signal is input to the arithmetic and control circuit 1.

The arithmetic and control circuit 1 detects a vibration transmission time to each sensor based on the detection timing input from the waveform detection circuit, and further detects a coordinate input position of the vibration pen 3 on the vibration transmission plate 8 from the vibration transmission time.

The detected coordinate information of the vibration pen 3 is processed in the arithmetic and control circuit 1 in accordance with the output method by the display 11 '.
That is, the arithmetic control circuit controls the output operation of the display 11 'via the video signal processing device 10 based on the input coordinate information.

FIG. 6 shows the structure of the arithmetic and control circuit 1 of FIG. Here, a structure of a drive system of the vibration pen 3 and a vibration detection system by the vibration sensor 6 is mainly shown.

The microcomputer 11 has an internal counter, a ROM 11a and a RAM 11b. The ROM 11a has the mark 8a,
The coordinate values of 8b and 8c are stored. In the RAM 11b, correction values used for vibration transmission time correction described later and values used for calculating position coordinates of the vibration sensor 6, ie, vibrations input from the marks 8a, 8b, and 8c of the vibration transmission plate 8, are stored. The transmission time to the vibration sensor 6 is stored.

The drive signal generation circuit 12 outputs a drive pulse of a predetermined frequency to the vibrator drive circuit 2 shown in FIG. 4, and is started by the micro computer 11 in synchronization with a coordinate calculation circuit.

The count value of the counter 13 is latched by the microcomputer 11 to the latch circuit 14.

On the other hand, the waveform detection circuit 9 outputs timing information of a detection signal for measuring a vibration transmission time from an output of the vibration sensor 6 as described later. These pieces of timing information are input to the input ports 15, respectively.

The timing signal input from the waveform detection circuit 9 is input to an input port 15 and each of the vibration sensors 6 in the latch circuit 14
Is stored in the storage area corresponding to the above, and the result is transmitted to the microcomputer 11.

That is, the vibration transmission time is expressed as a latch value of the output data of the counter 13, and the coordinate calculation is performed based on the vibration transmission time value. At this time, the determination circuit 16 determines whether all pieces of waveform detection timing information from the plurality of vibration sensors 6 have been input, and notifies the microcomputer 11 of the determination.

Output control processing of the display 11 ′ is performed through the input / output port 17.

FIG. 7 illustrates a detected waveform input to the waveform detection circuit 9 of FIG. 4 and a process of measuring a vibration transmission time based on the detected waveform, which is the same as described above. (P7, 8, 9) To measure the two vibration transmission times tg and tp shown in FIG. 7, the waveform detection circuit 9 can be configured as shown in FIG. 8, for example.

In FIG. 8, the output signal of the vibration sensor 6 is amplified to a predetermined level by the amplifier circuit 51 described above.

The amplified signal is input to the envelope detection circuit 52, and only the envelope of the detection signal is extracted. The peak timing of the extracted envelope is detected by the envelope peak detection circuit 53. As the peak detection signal, an envelope delay time detection signal Tg having a predetermined waveform is formed by a signal detection circuit 54 composed of a monomultivibrator or the like, and is input to the arithmetic and control circuit 1.

Also, the timing of this Tg signal and the delay time adjustment circuit
A phase delay time detection signal Tp is formed by the detection circuit 58 from the original signal delayed by 57, and is input to the arithmetic and control circuit 1.

That is, the Tg signal is converted into a pulse having a predetermined width by the monostable multivibrator 55. Further, the comparator level supply circuit 56 forms a threshold value for detecting the tp signal according to the pulse timing. As a result, the comparator level supply circuit 56 forms a signal 44 having a level and timing as indicated by reference numeral 44 in FIG.
To enter.

In other words, the monostable multivibrator 55 and the comparator level supply circuit 56 are for preventing the measurement of the phase delay time only for a certain period of time after the detection of the envelope peak.

This signal is a detection circuit composed of a comparator, etc.
The signal is input to 58 and compared with the detection waveform delayed as shown in FIG. 7, and as a result, a tp detection pulse as indicated by reference numeral 45 is formed.

The circuit shown above is for one of the vibration sensors 6, and
The same circuit is provided for each of the other sensors. If the number of sensors is generalized to h, the envelope delay time Tg1 to h and the phase delay time Tp1 to h
The detection signals are input to the arithmetic and control circuit 1.

The arithmetic control circuit shown in FIG. 6 receives the above-mentioned signals Tg1 to h and Tp1 to h from the input port 15, and takes the count value of the counter 13 into the latch circuit 14 with each timing as a trigger. As described above, since the counter 13 is started in synchronization with the driving of the vibration pen 3, the latch circuit 14 takes in data indicating the delay times of the envelope and the phase.

 Now, the sensor position coordinate calculating means will be described.

FIG. 1 shows a positional relationship between an input point on a mark 8a by a pen and a sensor. Although the figure shows only one sensor and one input point, the same applies to other sensors or input points on other marks.

In the figure, As shown in FIG. 10, the vibration transmission times tg ₁ and tp ₁ of the vibration detected at the point S ′ ₁ inputted from the point P ₁ have the circuit delay time et and the phase offset time tof as described above.
Is included.

That is, in the first diagram _{d '11 = n 11 λp +} Vp (tp 11 -ep) ... (20) However ep = et + tof (19) , (20) from equation _{{n 11 λp + Vp (tp} 11 -ep)} 2 = (X ₁ −a ₁ ) ² + (y ₁ −b ₁ ) ² ... (21) Similarly, by inputting at two points P ₂ and P ₃ on the marks 8 b and 8 c other than the point P ₁ ｛n _{21 ^{λp + Vp (tp 21 -ep)}} } 2 = (x 1 -a 2) 2 + (y 1 -b 2) 2 ... (22) {n 31 λp + Vp (tp 31 -ep)} 2 = (x 1 -a 3 ) ² + (y ₁ −b ₃ ) ² (23) is obtained.

In the above equations (21), (22), and (23), λp and Vp are constants, and a ₁ , b ₁ , a ₂ , b ₂ , a ₃ , and b ₃ are input points, ie, marks.
8a, 8b, 8c are of coordinates, _{known, tp 11, tp 21, tp} 31 is measured, i.e. unknowns is _{n 11, n 21, n 31} , ep, x 1, y 1. It is only necessary to know x ₁ and y ₁ among these unknowns.

By the way, from the above equation (3), n ₁₁ = [{Vg (tg ₁₁ −et) −Vp (tp ₁₁ −et−tof)} / λp + 1/2] (24) n ₂₁ = [｛Vg (tg ₂₁ −et) −Vp (tp ₂₁ −et−tof)｝ / λp + 1/2] (25) n ₃₁ = [{Vg (tg ₃₁ −et) −Vp (tp ₃₁ −et−tof)} / λp + 1/2 ] (26) The above (21), (22), (23), (24), (25),
By eliminating n ₁ , n ₂ , n ₃ , and ep from equation (26), and obtaining x ₁ and y ₁ , Where A ₂ = a ₁ -a ₂ A ₃ = a ₁ -a ₃ B ₂ = b ₁ -b ₂ B ₃ = b ₁ -b ₃ C ₂ = Vptp ₁₁ -k ₂₁ λp-Vptp ₂₁ C ₃ = Vptp _{11 -k 31 λp-Vptp 31 D 1} = 1/2 {a 1 2 + b 1 2 -a 2 2 -b 2 2 - (Vptp 11) 2 + (k 21 λptVptp 21) 2} D 2 = 1/2 { ^{_{a 1 2 + b 1 2 -a}} 3 2 -b 3 2 - (Vptp 11) 2 + (k 31 λptVptp 31) 2} k 21 = [{vg (tg 21 -tg 11) -Vp (tp 21 -tp 11 ｝ / Λp + 1/2] k ₃₁ = [｛vg (tg ₃₁ −tg ₁₁ ) −Vp (tp ₃₁ −tp ₁₁ ｝ / λp + 1/2) In the equation (27), x ₁ is a position S ₁ (0,
Considering that it is in the vicinity of 0), it is fixed to one. By substituting the stated x ₁ in (28),
y ₁ is found.

From the above, the actual sensor position S ′ ₁ (x ₁ , y ₁ ) is 3 points
It is determined by inputting P ₁ , P ₂ , and P ₃ .

Although the above description has been made with respect to one sensor, the actual positions S ′ ₂ , S ′ ₃ ... Of the other sensors are also obtained by the same method. At this time, it goes without saying that the input points to the other sensors may be the points P ₁ , P ₂ , and P ₃ described above.

In addition, when ΔS≪d ₁ is known in FIG. ₁ , three points of a predetermined distance d ₁ from the position S _{1 where} the sensor should be located are input to obtain (17), (18), and (19). In the equation, n ₁₁ = n ₂₁ = n ₃₁ (29) can be satisfied.

In this case, the above calculation is simplified, and the actual position of the sensor is easily calculated.

 Next, the input point coordinate calculation means will be described.

In this embodiment, the absolute coordinate system xy is set on the vibration transmission plate by means such as printing as shown in FIG.

In FIG. ₂ , design positions of _three sensors S ₁ , S ₂ , S ₃ in the absolute coordinate system xy are represented by S ₁ (0, 0), respectively.
S ₂ (x, 0), S ₃ (0, Y), the sensor in the absolute coordinate system xy obtained by the sensor position coordinate calculating means
The actual positions of S ₁ , S ₂ , and S ₃ are represented by S ′ ₁ (x ₁ , y ₁ ), S ′ ₂ (x ₂ ,
y ₂ ), S ′ ₃ (x ₃ , y ₃ ), and the coordinates of the input point P of the pen to be obtained in the absolute coordinate system are P (x, y). This calculation method is for obtaining P (x, y). Further line segment ▲
▼ is the angle between the x-axis of the absolute coordinate system and ξx, and the line segment ▲ ▼ is the angle between the y-axis of the absolute coordinate system and ξy
And the counterclockwise direction is positive.

First, from the input point P, each of the sensors S ′ ₁ , S ′ ₂ , S ′ ₃
The calculation of the distances d ′ ₁ , d ′ ₂ , and d ′ ₃ to will be described.

One point P ₁ (a ₁ ,
From b ₁ ) and the vibration transmission times tg ₁₁ and tp ₁₁ , the following equation is obtained for the sensor S ′ ₁ .

On the left side, x ₁ , y ₁ , a ₁ , and b ₁ are known, so that the left side is d ₀₁ (31). Here, n ₁₁ is expressed by equation (24).

Now, from the input point P sensor S 'T'p ₁ measurements of vibration transmission time to _1, when the T'g _1, d as in the conventional example by:' ₁ are calculated.

d ′ ₁ = d ₀₁ + (n ′ ₁ −n ₁ ) λp + Vp (t′p ₁ −t
p ₁ )... (32) n ′ ₁ −n ₁₁ [{Vg (t′g ₁ −tg ₁₁ ) −Vp (t′p ₁ −tp ₁₁ )} / λp + 1/2] (33) Similarly, input point distance _d from P to other sensors _{S '2, S' 3 '} 2, d' 3 is calculated.

Next, a description will be given of a means for obtaining the coordinates (x, y) of the input point P from the calculated d' ₁ , d' ₂ , and d' ₃ .

First, as shown in FIG. 2, the vibration sensors S _1, S _2, the actual position of the _{S 3 S '1 (x 1} , y 1), S' 2 (x 2, y 2), S '3
(X _3, y ₃₎ set the coordinate system x'-y 'of the point P in the coordinate (x' by, y ') think. Where the point S ' ₁ ,
The line connecting S ′ ₂ is the x ′ axis, and the line connecting points S ′ ₁ and S ′ ₃ is the y ′ axis. At this time, here Next, 'consider the parallel coordinate system x-y ₁ to the absolute coordinate system x-y whose origin, the coordinate system x'-y' point S as shown in Figure 3 the point in P (x ', y ') in the coordinate system x
Converting to -y, By translating the coordinate system xy in the absolute coordinate system xy, the coordinates (x, y) of the point P can be calculated by the following equation.

By the above calculation, the position coordinates of each sensor obtained by the aforementioned sensor position coordinate calculation means, the coordinate value of one of the input points used in the sensor position coordinate calculation means,
From the vibration transmission time from this one point to each vibration sensor and the vibration transmission time from the coordinate input point P to each sensor, it is possible to accurately calculate the coordinates (x, y) of the point P in the absolute coordinate system. it can.

Mark 8a, 8b, 8c of the coordinates _{(a 1, b 1),} (a 2, b 2),
(A ₃ , b ₃ ) are stored in the ROM 11a in advance. Also, the vibration transmission time from the marks 8a, 8b, 8c to each sensor, t
_{p 11, tg 11, tp 21} , tg 21, tp 31, tg 31, tp 12, tg 12, tp
_{22, tg 22, tp 32,} tg 32, tp 13, tg 13, tp 23, tg 23, t
p ₃₃ , tg ₃₃ , and the vibration transmission time and marks 8a, 8b, 8c
Actual position S ′ ₁ (x ₁ , calculated from the coordinates of
_{y 1), S '2 (} x 2, y 2), S' 3 (x 3, y 3) is stored in the RAM 11b.

The acquisition of the vibration transmission time may be performed at a predetermined timing, for example, immediately after the power is turned on, on the display 11 'to prompt the operator.

[Other embodiments]

About the sensor position coordinate calculation means, in FIG. By the way, as in the first embodiment, d ′ ₁₁ = n ₁₁ λp + Vp (tp ₁₁ −ep) (41) where ep = et + tof (40) Similarly, by inputting at three points P ₂ , P ₃ and P ₄ other than point P ₁ From the above equations (42), (43), (44) and (45), n ₁ ,
When n ₂ , n ₃ , n ₄ and ep are eliminated to obtain θ ₁ and ΔS ₁ , Where G ₁₁ = F ₂₁ (E ₄₁ −E ₃₁ ) + F ₃₁ (E ₂₁ −E ₄₁ ) + F ₄₁ (E ₃₁ −E ₂₁ ) G ₂₁ = E ₃₁ F ₄₁ −E ₄₁ F ₃₁ G ₃₁ = E ₂₁ F ₄₁ −E ₄₁ F ₂₁ G ₄₁ = E ₃₁ F ₂₁ −E ₂₁ F ₃₁ E ₂₁ = Vptp ₁₁ −k ₂₁ λp−Vptp ₂₁ E ₃₁ = Vptp ₁₁ −k ₃₁ λp−Vptp ₃₁ E ₄₁ = Vptp ₁₁ −k _{41 λp-Vptp 41 F 21 = (} Vptp 11) 2 - (k 21 λp + Vptp 21) 2 -d 2 11 + d 2 21 F 31 = (Vptp 11) 2 - (k 31 λp + Vptp 31) 2 -d 2 11 + d 2 31 F ₄₁ = (Vptp ₁₁ ) ² − (k ₄₁ λp + Vptp ₄₁ ) ² −d ² ₁₁ + d ² ₄₁ k ₂₁ = [{Vg (tg ₂₁ −tg ₁₁ ) −Vp (tp ₂₁ −tp ₁₁ )} / λp + 1/2 _{] k 31 = [{Vg (} tg 31 -tg 11) -Vp (tp 31 -tp 11)} / λp + 1/2] k 41 = [{Vg (tg 41 -tg 11) -Vp (tp 41 -tp 11 ) / Λp + 1/2] Then, by calculating the above θ ₁ and ΔS ₁ , the actual position coordinate S ′ ₁ (x ₁ , y ₁ ) of the vibration sensor is calculated by the following equation.

Although the above description has been made with respect to one sensor, the actual positions S ′ ₂ , S ′ ₃ ... Of the other sensors are also obtained by the same method. At this time, it goes without saying that the input points to the other sensors may be the points P ₁ , P ₂ , P ₃ , and P ₄ described above.

Further, similarly to the first embodiment, n ₁ = n ₂ = n ₃ = n ₄ (70) is satisfied. A point P ₁ equidistant from the desired position of the sensor,
Needless to say, by inputting P ₂ , P ₃ , and P ₄ , the actual position of the sensor can be obtained by a simple calculation.

Also, if the circuit delay time and the phase offset time are known in the sensor position coordinate calculation means, the input is made by inputting two points whose coordinate values are known with a vibrating pen and measuring the vibration delay time to the sensor. It goes without saying that the distance between the point and the sensor is calculated, and the actual position coordinates of the sensor can be calculated from the calculated value by the principle of triangulation.

Also, the input by the vibrating pen to the marks 8a, 8b, 8c is
The actual position S of each vibration sensor calculated from the vibration transmission time to each vibration sensor and the coordinate values of the marks 8a, 8b, 8c is taken instead of being performed by the operator at the time of assembly at the factory or at the time of shipment. ′ ₁ (x ₁ , y ₁ ), S ′ ₂ (x ₂ ,
y ₂ ), S ′ ₃ (x ₃ , y ₃ ), and D′ x, D′ y, tan
ξx, tanξy, cosξx, and cosξy may be stored in a nonvolatile memory or the like. In this case, by using a stage or the like, more accurate input to the marks 8a, 8b, 8c becomes possible.

In the first embodiment, the absolute coordinate system xy is provided by printing on the vibration transmission plate. However, the present invention is not limited to this, and a chassis for supporting the vibration transmission plate 8 as shown in FIG.
The absolute coordinate system xy may be set by holes 21a and 21b provided in 21.

Further, any orthogonal line on the display 11 may be set as the absolute coordinate system xy.

Further, two sides of the vibration transmission plate 8 may be defined as an absolute coordinate system xy.

〔The invention's effect〕

As described above, a vibration transmission plate that transmits vibration,
A plurality of vibration sensors provided on the vibration transmission plate, and input point coordinate calculating means for measuring a vibration transmission time from the input point to each vibration sensor and calculating a coordinate value of the input point from the measured value. In a coordinate input device, the coordinate values are defined, an absolute coordinate system set on the vibration transmission plate, and vibrations from two or more input points whose coordinate values are known in the absolute coordinate system to each of the vibration sensors. A sensor position coordinate calculating means for calculating a coordinate value of the position of each vibration sensor in the absolute coordinate system from the transmission time; a position coordinate value of each vibration sensor calculated by the sensor position coordinate calculating means; At least one used in the operation
By providing a calculating means for calculating the coordinate value of the input point based on the input coordinate value of the point and the transmission time, it is possible to input at two or more points with respect to the displacement of the vibration sensor which causes a decrease in accuracy. By simple means, the coordinate value of the actual position of the vibration sensor can be calculated, and by calculating the coordinate value of the input point including the calculated coordinate value of the position of the vibration sensor, the accurate coordinate value of the input point can be calculated. Can be obtained.

[Brief description of the drawings]

1 is an explanatory view of a sensor position coordinate calculating means of the present invention, FIGS. 2 and 3 are explanatory views of an input point coordinate calculating means of the present invention, and FIG. 4 is a diagram of an information input / output device employing the present invention. FIG. 5 is an explanatory diagram showing the structure of the vibrating pen of FIG. 4, FIG. 6 is a block diagram showing the structure of the arithmetic and control circuit of FIG. 4, and FIG. 7 is a vibrating pen. 8 is a waveform diagram showing a detection waveform for explaining the distance measurement between the sensor and the vibration sensor, FIG. 8 is a block diagram showing the configuration of the waveform detection circuit in FIG. 4, and FIG. 9 is an explanation showing the arrangement of the vibration sensor. FIG. 10 is a diagram showing the relationship between the delay time and the distance between the pen and the sensor. FIG. 11 is an explanatory diagram of another embodiment of the absolute coordinate system xy. 1 arithmetic control circuit 3 vibrating pen 4 vibrator 6 vibration sensor 8 vibration transmission plate 8a mark 11 microcomputer 11a ROM 11b RAM

──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsuyuki Kobayashi, Inventor 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Takeshi Kamono 3-30-2, Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Kiyoshi Kaneko 3-3-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Jun Tanaka 3-2-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. ( 56) References JP-A-63-314634 (JP, A) JP-A-1-237712 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G06F 3/03

Claims (4)

(57) [Claims] 1. A vibration transmitting plate for transmitting vibration, a plurality of vibration sensors provided on the vibration transmitting plate, and a vibration transmission time from an input point to each vibration sensor are measured. A coordinate input device having input point coordinate calculating means for calculating the coordinate value of: an absolute coordinate system that defines the coordinate value and is set on the vibration transmission plate; and the coordinate value is known in the absolute coordinate system. 2
A sensor position coordinate calculating means for calculating a coordinate value of a position of each vibration sensor in the absolute coordinate system from a vibration transmission time from an input point equal to or more than the point to each of the vibration sensors; Calculating means for calculating the coordinate value of the input point based on the position coordinate value of each vibration sensor and the input coordinate value and the transmission time of at least one point used in the calculation of the sensor position coordinate. A coordinate input device. 2. A storage means for storing a measured value of a vibration transmission time of a vibration inputted from a point on the vibration transmission plate at which a coordinate value is known to each of the vibration sensors and the coordinate value as a correction value. The calculation means calculates the coordinate value of the input point from the measured value of the vibration transmission time from the input point for which the correction value and the coordinate are to be obtained to each of the vibration sensors and the coordinate value of the position of each of the vibration sensors. The coordinate input device according to claim 1, wherein 3. A vibration transmission plate for transmitting vibration, a plurality of vibration sensors provided on the vibration transmission plate, and a vibration transmission time from the input point to each vibration sensor are measured. In a coordinate input method of a coordinate input device having input point coordinate calculating means for calculating a coordinate value of a point, the coordinate value is defined, an absolute coordinate system set on the vibration transmission plate, and coordinates in the absolute coordinate system. 2 whose value is known
A sensor position coordinate calculation step of calculating a coordinate value of the position of each vibration sensor in the absolute coordinate system from a vibration transmission time from the vibration pen to each of the vibration sensors at a point or more; and a sensor position coordinate calculation step. A calculating step of calculating the coordinate value of the input point based on the coordinate value of the position of each vibration sensor and the input coordinate value and the transmission time of at least one point used in calculating the position coordinate of the sensor; A coordinate input method comprising: 4. A storage step of storing a measured value of a vibration transmission time of a vibration inputted from a point on the vibration transmission plate at which a coordinate value is known to each of the vibration sensors and the coordinate value as a correction value. Wherein the calculating step calculates a coordinate value of an input point from a measured value of a vibration transmission time from the input point to obtain the correction value and the coordinates to each of the vibration sensors and a coordinate value of a position of each of the vibration sensors. The coordinate input method according to claim 3, wherein: