JP2546884B2 - Coordinate input device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate input device, and in particular, a vibration input by a vibrating pen is detected by a plurality of vibration sensors provided on a vibration transmitting plate to transmit the vibration of the vibrating pen. The present invention relates to a coordinate input device that detects coordinates on a board.

[Prior Art] In this type of device, the input vibration from the vibrating pen is detected by a plurality of vibration sensors provided on the vibration transmission plate. However, the influence of phase delay and vibration of the vibration transmission plate on the vibration transmission plate A highly accurate coordinate input value cannot be obtained unless the influence of the circuit delay time of all circuits from generation to detection is corrected. The circuit delay time includes not only the delay of the electric circuit but also the delay inherent to the mechanical vibration transmission circuit in the vibration pen and the vibration transmission plate. Therefore, it is conceivable to correct the coordinate input data at an arbitrary point based on the reference data coordinate input with a certain point as a reference.

[Problems to be Solved by the Invention] However, if a reference point is selected at an arbitrary position, for example, for i vibration sensors, i reference distances l ₁ , l ₂ , l ₃ … L _i will be present, and much reference data must be stored in memory.

Also in manufacturing the device, it is extremely difficult to determine a position on the vibration transmission plate that simultaneously satisfies the distances l _{1 to} l _i from each vibration sensor.

The present invention eliminates the above-mentioned drawbacks of the prior art, and an object thereof is to provide a coordinate input device that is easy to manufacture and has high coordinate input accuracy.

[Means for Solving the Problems] In order to achieve the above object, the coordinate input device of the present invention is
In a coordinate input device that detects the vibration input from the vibrating pen by a vibration sensor provided on the vibration transmitting plate to detect the coordinates on the vibration transmitting plate of the vibrating pen, a detection timing signal is generated from the generation of the drive signal pulse. The delay time until being detected, the measuring means for measuring a plurality of points at a known distance from one of the vibration sensors, and based on the measurement result by the measuring means, from the vibration sensor, a known Storage means for deriving and storing the delay time up to the average distance as a delay time with respect to a reference point, and a detection timing signal detected from drive signal pulse generation of an input made at an arbitrary point on the vibration transmission plate The delay time until it is measured is measured by the plurality of vibration sensors, and is calculated from the difference between the delay time and the delay time stored in the storage means. Means for deriving the vibration transmission time in the vibration transmission plate from the arbitrary point to the reference point for each of the plurality of vibration sensors, and the distance from the arbitrary point to the reference point from the derived vibration transmission time Alternatively, it is summarized as including a derivation unit that derives a distance from the arbitrary point to the vibration sensor.

[Operation] In such a configuration, the storage means stores the delay time of vibration transmission at an average distance from each of the plurality of vibration sensors to a plurality of known equidistant points as a delay time to the reference point. The deriving unit derives the vibration transmission delay time from the arbitrary point to the reference point from the stored delay time with respect to the average distance, and further derives the distance from the arbitrary point to the reference point or the vibration sensor.

[Description of Embodiments] Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of the coordinate input device of the embodiment. In the figure, reference numeral 3 denotes a vibration pen, which is used by a user to carry out coordinate input at a position on the vibration transmission plate 8. That is, the vibrating pen 3 has a vibrator 4 made of a piezoelectric element or the like inside, and transmits the ultrasonic vibration generated by the vibrator 4 to the vibration transmitting plate 8 via the horn portion 5 having a sharp tip. I do. Reference numeral 2 denotes a vibrator driving circuit, which drives the vibrator 4 in pulses. Reference numeral 8 denotes a vibration transmission plate, which is made of, for example, an acrylic plate, a glass plate, or the like. The vibration transmission plate 8 transmits the ultrasonic vibration received from the vibration pen 3 to the vibration sensors 6a to 6c including the piezoelectric elements provided at the corners. Reference numeral 8a is a reference mark, which is an equal distance R from each of the vibration sensors 6a to 6c on the vibration transmission plate 8.
Is provided at the point. Reference numeral 7 denotes an anti-reflection material, which is made of, for example, silicon rubber. The anti-reflection member 7 supports the vibration transmitting plate 8 and also prevents the ultrasonic vibration transmitted through the vibration transmitting plate 8 from being reflected at the peripheral portion thereof and returning to the central portion. A signal waveform detection circuit 9 outputs a detection timing signal corresponding to the ultrasonic vibration detection signals detected by the respective vibration sensors 6a to 6c. An arithmetic / control circuit 1 performs main control of the apparatus and arithmetic of input coordinates. That is, while the ultrasonic pulse signal is sent to the vibrator drive circuit 2, the internal timer is started, and each vibration sensor is sent from the time when the pulse signal is sent based on each detection timing signal input from the signal waveform detection circuit 9. 6a
The vibration transmission time until the vibration is transmitted to 6c is detected, and the input coordinates (x, y) of the vibration pen 3 on the vibration transmission plate 8 are obtained based on the detected vibration transmission time information.

The input coordinates (x, y) thus obtained are further used in various ways by the arithmetic / control circuit 1. That is, the arithmetic and control circuit 1 variously controls the output operation of the display 11 'via the display drive circuit 10 based on the obtained input coordinates (x, y).

Therefore, the vibration transmitting plate 8 is preferably superimposed on a dot display 11 'such as a CRT or a liquid crystal display, and performs dot display at a position traced by the vibrating pen 3, for example. That is, a dot display is performed at a position on the display 11 'corresponding to the position of the vibrating pen 3, and when the vibrating pen 3 is moved, an image composed of elements such as dots and lines vibrates as if written on paper. It follows the trajectory of the pen 3. Alternatively, an input method may be used in which a menu is displayed on the display 11 ', and the menu item is selected by the vibration pen 3, or a prompt is displayed to bring the vibration pen 3 into contact with a predetermined position.

FIG. 2 is a view showing the structure of the vibration pen 3 of the embodiment.
The same components as those in FIG. 1 are denoted by the same reference numerals. In the figure, a low level (for example, 5 V
) Is transmitted. Vibrator drive circuit 2
Is a circuit that can drive the output with low impedance.
The low-level input pulse signal is amplified with a predetermined gain and applied to the vibrator 4. The vibrator 4 converts the electric drive signal into mechanical ultrasonic vibration, and the ultrasonic vibration is transmitted to the vibration transmission plate 8 via the horn 5. The vibration frequency of the vibrator 4 is selected within a range capable of generating a plate wave on the vibration transmission plate 8 made of an acrylic plate, a glass plate, or the like. Further, when the vibrator 4 is driven, a vibration mode in which the vibrator 4 vibrates mainly in the direction perpendicular to the surface of the vibration transmission plate 8 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. Since the elastic wave transmitted to the vibration transmitting plate 8 in this manner is a plate wave, it has an advantage that it is less affected by scratches or obstacles on the surface of the vibration transmitting plate 8 than surface waves.

FIG. 3 is a block diagram of the arithmetic and control circuit 1 of the embodiment. In the figure, reference numeral 11 denotes a micro computer (CP
U) to perform various calculations and controls. 11a is a ROM storing a program to be executed by the CPU 11, and 11b is a RAM used by the CPU 11 as a work area. The ROM 11a stores data on the true vibration transmission time from the reference mark 8a to at least one vibration sensor. This data is measured and stored during manufacturing, for example. RAM1
Reference numeral 1b stores actually measured vibration transmission time data when an instruction is input to the reference mark 8a with the vibration pen 3. Such instruction input to the reference mark 8a is performed, for example, when the power of the device is turned on or when the device is in use, as needed. A drive signal generation circuit 12 outputs a drive pulse signal of a predetermined frequency to the vibrator drive circuit 2 in synchronization with a start signal from the CPU 11. A start signal from the CPU 11 causes the timer counter 13 to start counting operation.

On the other hand, the signal waveform detection circuit 9 outputs various detection timing signals (timing pulse signals) for measuring the vibration transmission time by catching the detection outputs of the vibration sensors 6a to 6c. The various detection timing signals refer to detection timing signals t _{g1 to} t _{gh of} envelope signals and detection timing signals t _{p1 to} t _ph of phase signals, which will be described later, if the number of vibration sensors 6 is generalized to h. . These detection timing signals are input to the detection signal input port 15 in parallel. A latch circuit 14 latches the content (vibration transmission time) of the counter 13 according to the input of each detection timing signal, and holds it in the storage area corresponding to each vibration sensor 6a-6c. Reference numeral 16 denotes a determination circuit, which determines whether or not the detection timing signal from all the vibration sensors is input, and when it is input, notifies the CPU 11 to that effect. As a result, the CPU 11 calculates the coordinates (x, y) at which the vibrating pen 3 is placed based on the vibration transmission time for each of the vibration sensors 6a to 6c. Reference numeral 17 is an I / O port, which is an external circuit.
This is done via I / O port 17.

FIG. 4 is a timing chart for explaining the mode of vibration transmission of the embodiment. In the figure, a signal 41 is an ultrasonic pulse signal generated by the drive signal generating circuit 12. According to this, the vibrator 4 vibrates ultrasonically, and the ultrasonic vibration vibrates.
Is transmitted to the vibration transmission plate 8 via. Further, the ultrasonic vibration is transmitted through the vibration transmission plate 8 and detected by the respective vibration sensors 6a to 6c. The signal 42 indicates the signal waveform detected by the vibration sensor 6. The plate wave of the embodiment is a dispersive wave, and the relative relationship between the envelope signal 421 and the phase signal 422 of the detected waveform changes according to the vibration transmission distance. Now the envelope signal
Assuming that the traveling speed of 421 is the group velocity V _g and the traveling speed of the phase signal 422 is the phase velocity V _p , the distance between the vibration pen 3 and each of the vibration sensors 6a to 6c is based on the group velocity V _g and the phase velocity V _p. I want it.

First, focus only on the envelope signal 421. Group velocity V _g
The propagation of the signal is detected by detecting the arrival of a specific point on the envelope signal 421, for example, the peak point. signal
43 is a peak point detection timing signal, which is a pulse signal
The time t _g from the occurrence of 41 to the detection of the peak point is the measured vibration transmission time. Also since the group velocity V _g is known, the distance d between the vibration sensors 6a~6c the vibration pen 3 is obtained by (1).

d = V _g · t _g (1) Further, when the position detection accuracy (tablet resolution) of the vibration pen 3 is increased, processing based on the detection of the phase signal 422 is added. That is, a certain point on the phase signal 422, for example, the time from the generation time of the pulse signal 41 to the first zero-cross point after the peak detection for the envelope signal 421.
detects the t _p, determined the vibration pen 3 to the distance between the vibration sensors 6a~6c in (2).

d = n · λ _p + V _p · t _p (2) where λ _p : wavelength of elastic wave n: integer The integer n is obtained by the formula (3) from the formulas (1) and (2).

Here, the symbol [] is a Gaussian symbol. N is a real number other than "0", and an appropriate numerical value is used. For example N
= 2, n can be determined within ± 1/2 wavelength.
Thus, the accurate distance d is obtained by substituting n obtained by Expression (3) into Expression (2).

FIG. 5 is a block diagram of the signal waveform detection circuit of the embodiment. In the figure, a preamplifier circuit 51 amplifies the output signal of the vibration sensor 6 to a predetermined level. The envelope detection circuit 52 extracts only the envelope signal from the amplified signal. The envelope peak detection circuit 53 detects the peak of the envelope signal and triggers the t _g signal detection circuit 54 at the detection timing. The t _g signal detection circuit 54 is composed of, for example, a mono multivibrator circuit. The arithmetic / control circuit 1 uses the counter 13 at the timing of receiving the signal t _g.
Obtaining a vibration transmission time t _g by the speed V _g groups based on the output.

On the other hand, the rising edge of the t _g signal is the monostable multivibrator 55.
Is triggered to output a signal 44 having a predetermined pulse width. The comparator level supply circuit 56 forms the threshold signal 44 for detecting the t _p signal only during the period of this pulse signal. The comparator t _p detection circuit 58 compares the threshold signal 44 with the phase signal 422 time-adjusted by the delay time adjustment circuit 57, and detects the detection timing signal t _p corresponding to the portion where the phase signal 422 exceeds the threshold signal 44. Output. The arithmetic / control circuit 1 obtains the transmission time at the phase speed V _p based on the output of the counter 13 at the generation timing of the detection timing signal t _p . The configuration of such a waveform detection circuit is provided for each system of the vibration sensors 6a to 6c, and therefore the distance from the coordinate input point to each of the vibration sensors 6a to 6c is obtained.

FIG. 6 is a diagram for explaining the coordinate calculation processing of the embodiment.
By the way, the count value (vibration transmission time) latched by the latch circuit 14 actually includes a circuit delay time t _e peculiar to the circuit from the drive signal generation circuit 12 to the detection signal input port 15. . Also, when the phase signal 422 contains a steady phase offset amount, the phase offset time t _of
Also needs to be considered. Therefore, first consider removing the circuit delay time t _e and the phase offset time t _of .

The user points the reference mark 8a with the vibrating pen 3 when the power of the apparatus is turned on or at an appropriate time during use, for example. As a result, measured values t _gr ′, t _pr ′ of the vibration transmission time from the reference mark 8a to each vibration sensor are obtained, and these can be expressed as in equations (4) and (5).

t _gr ′ ＝ t _gr ＋ t _e … (4) t _pr ′ ＝ t _pr ＋ t _e ＋ t _of … （5） where t _gr , t _pr : true transmission time t _e from the reference mark 8a to the vibration sensor 6 : Circuit delay time t _of : Phase offset time Next, the CPU 11 stores the measured values t _gr ′, t _pr ′ in the RAM 11b.

Further, during use of the apparatus, the vibrating pen 3 is used to indicate an arbitrary input point P for various purposes. As a result, measured values t _gp ′ and t _pp ′ regarding the input point P are obtained, and these can be expressed in the same manner as the equations (6) and (7).

t _gp ′ = t _gp ＋ t _e … (6) t _pp ′ ＝ t _pp ＋ t _e ＋ t _of … (7) where t _gp , t _pp : true transmission time from the input point P to the vibration sensor Calculates the difference between the measured value of the input point P and the measured value of the reference mark 8a read from the RAM 11b. This corresponds to performing the operations of the expressions (8) and (9).

t _gp ′ −t _gr ′ = t _gp −t _gr (8) t _pp ′ −t _pr ′ = t _pp −t _pr (9) That is, the circuit delay time is calculated from the equations (8) and (9). The t _e and the phase offset time t _of have been removed. Moreover,
The right side of equations (8) and (9) is the reference mark 8a and the input point P.
Represents the difference in the true vibration transmission time between the two.

In FIG. 6, three vibration sensors 6a to 6c are provided at the corners of the vibration transmission plate 8, and the coordinates of each vibration sensor are
6a = S ₁ (0,0), 6b = S ₃ (0, Y), 6c = S ₂ (X, 0). Further, since the true transmission times t _gr and t _pr from the reference mark 8a to at least one vibration sensor are obtained in advance and are known, the true differences obtained by the equations (8) and (9) are added to these true differences. Input point P by adding true transmission time t _gr , t _pr
The true transmission times t _g and t _p corresponding to So CPU11
Is the distance d ₁ ~ in FIG. 6 according to the equations (2) and (3).
Find d ₃ . Then, according to the Pythagorean theorem, the coordinates (x, y) of the input point P are obtained by the equations (10) and (11).

As described above, according to the present embodiment, the reference mark 8a is provided on the vibration transmission plate 8, and the user sets the reference mark for correction by pointing the reference mark 8a when the apparatus is turned on or periodically. It is possible to provide a highly accurate coordinate input device that can easily obtain data and is not affected by fluctuations in the operating environment.

Further, even if the reference mark 8a is not provided on the vibration transmission plate 8, the reference data for correction can be obtained by carrying out the coordinate input operation at the position corresponding to the reference mark 8a at the time of factory shipment. It is possible to provide a coordinate input device in which variations between devices are eliminated. Moreover, since the distance R is constant, the only reference data stored can be used for all vibration sensor systems.

Further, for example, if the sensor arrangement as shown in FIG. 7 is used, the reference mark 8a is located at the intersection of the diagonal lines connecting the vibration sensors 6d to 6f and at the same distance from the vibration sensors 6d to 6f, so that the drawing is easy. Then, the only reference data should be stored.

[Other Embodiments] FIG. 8 is a front view of a vibration transmitting plate according to another embodiment. In this example, the number of vibration sensors is two, and each vibration sensor 6
Points equidistant from g and 6h are all points on the straight line L. Therefore, a highly accurate coordinate input device can be constructed by performing the above-mentioned correction at several points on the straight line L (for example, points 8a and 8b) and taking the average of each correction value. Of course, the method of averaging the correction values can be similarly realized with the number of sensors as shown in FIG.

As described above, according to the present invention, the vibration transmission time at the average distance from the vibration sensor to a plurality of points at a known distance is stored as the vibration transmission time to the reference point, and the value is stored. Since the distance from the arbitrary vibration input point to the reference point or the vibration sensor is derived based on this, the error of the delay time with respect to the reference point, especially the error at the time of measurement is reduced, and more accurate coordinate input becomes possible.

In addition, since the distance from each vibration sensor to the arbitrary vibration input point is derived based on the time difference, vibration or signal delay due to the internal configuration of the device or signal delay due to environmental changes may affect the measurement. It is possible to input highly accurate coordinates without receiving them.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a coordinate input device of the embodiment, FIG. 2 is a diagram showing a structure of a vibrating pen 3 of the embodiment, FIG. 3 is a block configuration diagram of an arithmetic / control circuit 1 of the embodiment, and FIG. FIG. 5 is a timing chart for explaining the mode of vibration transmission of the embodiment, FIG. 5 is a block diagram of the signal waveform detection circuit of the embodiment, FIG. 6 is a view for explaining the coordinate calculation processing of the embodiment, and FIG. The figure which shows the other sensor arrangement | positioning of an Example, FIG. 8 is a front view of the vibration transmission plate of another Example. In the figure, 1 ... calculation / control circuit, 3 ... vibration pen, 4 ...
Vibrator, 6a to 6h ... Vibration sensor, 8 ... Vibration transmission plate, 8a
…… Reference mark, 11 …… CPU, 11a …… ROM, 11b …… RAM
Is.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Shinnosuke Taniishi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Takeshi Kamono 3-30-2 Shimomaruko, Ota-ku, Tokyo Ki Within Canon Inc. (72) Inventor Ryozo Yanagisawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Within Canon Inc. (56) Reference JP-A-59-41090 (JP, A)

Claims (1)

(57) [Claims] 1. A coordinate input device for detecting vibrations input from a vibrating pen by a plurality of vibration sensors provided on a vibration transmitting plate to detect coordinates of the vibrating pen on the vibration transmitting plate. From the one of the vibration sensors to a delay time from the detection of the detection timing signal to a plurality of points at a known distance; From the drive signal pulse generation of the storage means for deriving and storing the delay time to the average distance of the known distances about the points as the delay time with respect to the reference point, and the input made to the arbitrary point on the vibration transmission plate. The delay time until the detection timing signal is detected is measured by the plurality of vibration sensors, and the delay time and the delay time stored in the storage means are measured. From the difference of, for each of the plurality of vibration sensors, means for deriving the vibration transmission time in the vibration transmission plate from the arbitrary point to the reference point, and from the derived vibration transmission time, from the arbitrary point to the Derivation means for deriving a distance to a reference point or a distance from the arbitrary point to the vibration sensor.