JPH01237711A - Coordinate input device - Google Patents

Abstract

PURPOSE:To obtain an exact coordinate value by constituting a coordinate input device so that a circuit delay time and an off-set time can not be included into respective oscillation transmission times from a prescribed point on an oscillation transmission board to respective oscillating sensors and from an oscillating pen to the respective oscillating sensors. CONSTITUTION:The outer circumference of an oscillation transmission board 8, which is made of acrylic resin and glass, etc., is surrounded by a reflection preventing member 7 of silicone rubber and oscillating sensors 6 are respectively provided in the three corner parts of this board. Next, here, a tip horn part 5 of an oscillating pen 3, for which an oscillator 4 to be composed of a piezoelectric element, etc., is built in, is pressed and driving by an oscillator driving circuit 2 and oscillation to be generated in the transmission board 8 is detected by the three sensors. Next, the transmission time of a transmitted ultrasonic signal is measured and the coordinate of the pen 3 on the transmission board 8 is detected. Then, the coordinate is caused to be correspondent to a position, which is traced by the pen 3, and a dot to correspond to the coordinate is displayed on a dot display 11 of a CRT and a liquid crystal display device, etc. Thus, delay and off-set, etc., are not generated in a process to obtain the coordinate and the exact coordinate value can be sent to an arithmetic control circuit 1.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention detects vibrations input from a coordinate input device, particularly a vibrating pen, using a plurality of vibration sensors provided on a vibration transmitting plate, and transmits the vibrations of the vibrating pen. This invention relates to a coordinate input device that detects coordinates on a board.

[Prior Art] In the coordinate detection method described above, the structure of the vibration transmission plate constituting the input tablet is simple, and since a transparent material can be used as the vibration transmission plate, it is possible to overlap the display, document, etc. It has the advantage of being able to be placed anywhere.

In this type of coordinate input device, input vibration from the vibrating pen is detected by multiple vibration sensors installed on the vibration transmission plate, but due to the influence of phase delay during vibration transmission on the vibration transmission plate, the detection circuit Correct coordinate values cannot be detected unless the influence of circuit delay time is corrected.Zero circuit delay is caused not only by the electrical circuit but also by the circuit in which vibration is mechanically transmitted between the vibrating pen and the vibration transmission plate. It also includes any inherent delays.

[Problems to be Solved by the Invention] Figure 8 shows the group delay time tg during which the envelope of the vibration waveform travels a certain distance, with the horizontal axis representing time t and the vertical axis representing the vibration transmission distance from the input point to the vibration sensor. This shows the change in the phase delay time tp during which the phase of the waveform progresses.

As shown in the figure, the circuit delay time et is always included in the distance O, and the curve ff1 (straight line) of each delay time is offset to the right of the graph. In addition, although the phase waveform produces a regular phase delay as shown in the figure depending on the wavelength, the difference tof between the group delay time tg and the phase delay time at the distance O, that is, the phase offset changes due to the influence of the circuit delay time. do.

In the method of measuring the vibration transmission time by detecting the transverse wave component on the vibration transmission plate, a method is known in which the vibration transmission time is determined using both the group delay time tg and the phase delay time tp. In such a method, correct vibration transmission time cannot be obtained unless the circuit delay time et and phase offset htof are corrected.

For this reason, conventional methods have been known in which a correction value is stored in advance according to a constant average circuit delay time eL and a phase offset (tof), and the vibration transmission time is corrected by subtracting this value from the measured value. There is.

However, this circuit delay time et, phase offset) to
To determine f, it is necessary to perform calculations on data sampled at a certain point using constants such as group velocity, phase velocity, and period. Therefore, errors in values such as velocity, and Calculation errors may lead to a decrease in accuracy in determining coordinates.

Furthermore, since the actual circuit delay time changes depending on environmental changes such as temperature, the conventional method has a problem in that it is not possible to accurately measure vibration propagation time regardless of changes in environmental conditions.

The object of the present invention is to solve the above problems.

[Means for Solving the Problems] In order to solve the above problems, in the present invention, vibrations input from a vibrating pen are detected by a plurality of vibration sensors provided on a vibration transmission plate, and vibrations of the vibrating pen are detected. In a coordinate input device for detecting coordinates on a transmission plate, means for measuring vibration transmission time from a predetermined point on the vibration transmission plate to each of the vibration sensors and storing the measured vibration transmission time as a correction value; The vibration transmission time from the coordinate input point by the vibrating pen to each of the vibration sensors is measured, and the correction value stored in the storage means is subtracted from this measured value to correspond to the distance from the predetermined point to the coordinate input point. A configuration was adopted that includes a control means that calculates the vibration transmission time and performs coordinate calculations based on this time value.

[Operation] According to the above configuration, the vibration transmission time from the predetermined point to each vibration sensor and the vibration transmission time from the input point to each vibration sensor similarly include circuit delay time and phase offset time. Therefore, by subtracting these, it is possible to calculate the vibration transmission time with the circuit 'lI delay time and phase offset time removed. This vibration transmission time corresponds to the distance from a predetermined point measured from the vibration sensor position to the input point, so if coordinate calculations are performed based on this vibration transmission time, it will be accurate regardless of the effects of circuit delay time and phase offset time. coordinate values can be obtained.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

FIG. 1 shows the structure of an information input/output device employing the present invention. The information input/output device shown in FIG. 1 inputs coordinates to an input tablet consisting of a vibration transmission plate 8 using a vibrating pen 3, and a display 11'' consisting of a CRT placed over the input tablet according to the input coordinate information. The input image is displayed on the screen.

In the figure, a vibration transmitting plate 8 is made of acrylic, glass, or the like and transmits vibrations transmitted from the vibrating pen 3 to three vibration sensors 6 provided at its corners. In this embodiment, the transmission time of the ultrasonic vibration transmitted from the vibrating pen 3 to the vibration sensor 6 via the vibration transmitting plate 8 is calculated by A1.
1, the coordinates of the vibrating pen 3 on the vibration transmission plate 8 are detected.

The vibration transmitting plate 8 has its peripheral portion supported by an anti-reflection material 7 made of silicone rubber or the like in order to prevent vibrations transmitted from the vibrating pen 3 from being reflected at the peripheral portion and returning toward the center. ing.

The vibration transmission plate 8 is disposed on a display device 11' capable of displaying dots, such as a CRT (or liquid crystal display), and displays dots at the position traced by the vibrating pen 3. In other words, a dot is displayed at a position 11 degrees above the display corresponding to the detected coordinates of the vibrating pen 3, and the image composed of elements such as points and lines input by the vibrating pen 3 is as if written on paper. Appears after the trajectory of the vibrating pen as if it were done.

Further, according to such a configuration, a menu is displayed on the display tt', and the menu item 1 is selected using the vibrating pen, or a prompt is displayed and the vibrating pen 3 is brought into contact with a predetermined position. Input methods can also be used.

Furthermore, in this embodiment, a mark 8a is provided at a predetermined position ia (the position is completely arbitrary) on the input surface of the vibration transmission plate 8, and the coordinates of this mark 8a are stored in advance in a ROM etc. The vibration transmission time to each vibration sensor 6 is measured, and this measured value is used to correct the vibration transmission time. The correction method will be explained in detail later.

The vibrating pen 3 that inputs ultrasonic vibrations to the vibration transmission plate 8 has a vibrator 4 made of a piezoelectric element or the like inside.
Ultrasonic vibrations generated by the vibrator 4 are transmitted to the vibration transmission plate 8 via the horn portion 5 having a sharp tip.

FIG. 2 shows the structure of the vibrating pen 3. A vibrator 4 built into the vibrating pen 3 is driven by a vibrator drive circuit 2. The drive signal for the vibrator 4 is supplied as a low-level pulse signal from the arithmetic and control circuit 1 shown in FIG. is applied to

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

The vibration frequency of the vibrator 4 is selected to a value that can generate plate waves on the vibration transmission plate 8 made of acrylic, glass, or the like. Further, when driving the vibrator, a vibration mode is selected in which the vibrator 4 mainly vibrates in the vertical direction in FIG. 2 with respect to the vibration transmission plate 8. Also, the vibration frequency of the vibrator 4 is set to
Efficient vibration conversion is possible by setting the resonance frequency to .

The elastic waves transmitted to the vibration transmission plate 8 as described above are plate waves, which have the advantage of being less affected by scratches, obstacles, etc. on the surface of the vibration transmission plate 8 compared to surface waves.

Again, in FIG. 1, 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 timing of vibration arrival at each sensor is detected by waveform detection processing described later. This detection timing signal is input to the arithmetic control circuit l.

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

The detected coordinate information of the vibrating pen 3 is processed in the arithmetic control circuit 1 according to the output method by the display 11'.

That is, the arithmetic control circuit controls the output operation of 11'' to the display via the video signal processing unit 10 based on the input coordinate information.

FIG. 3 shows the structure of the arithmetic control circuit l shown in FIG.

Here, the structure of the drive system of the vibrating pen 3 and the vibration detection system using the vibration sensor 6 are mainly shown.

The microcomputer 11 has an internal counter and a ROM 11.
It has built-in RAMI a and RAMI b. ROM1l
The coordinate value of the previous mark 8a is stored in a. Also,
RAM Ib stores a correction value used for vibration transmission time correction, which will be described later, that is, the transmission time of the vibration input from the mark 8a of the vibration transmission plate 8 to each vibration sensor 6.

The drive signal generation circuit 12 has a mode (7)-t' which outputs drive pulses of the same predetermined wave number to the vibrator drive circuit 2 shown in FIG.
, are activated by the microcomputer 11 in synchronization with the coordinate calculation circuit.

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

On the other hand, the waveform detection circuit 9 outputs timing information of a detection signal for calculating the total vibration transmission time 11- from the output of the vibration sensor 6 as described later. These timing information are input to the input ports 15, respectively.

The timing signal inputted from the waveform detection circuit 9 is inputted to the input port 15 and recorded in the storage area corresponding to each vibration sensor 6 in the latch circuit 14, and the result is transmitted to the microcomputer 11.

In other words, the output data of the counter 13 is latched lI'
The vibration transmission time is expressed as I, and coordinate calculations are performed using this vibration transmission time value. At this time, the determination circuit 16
determines whether all waveform detection timing information from the plurality of vibration sensors 6 has been input, and notifies the microcomputer 11 of the information.

Output control processing for the display device 11' is performed via the input/output port 17.

, FIG. 4 explains the detected waveform input to the waveform detection circuit 9 of FIG. 1 and the total Δ1-i processing of the vibration transmission time based on the detected waveform. In FIG. 4, reference numeral 41 indicates a drive signal pulse applied to the vibrating pen 3. Ultrasonic vibrations transmitted from the vibrating pen 3 driven by such a waveform to the vibration transmission plate 8 pass through the vibration transmission plate 8 and are detected by the vibration sensor 6.

After traveling within the vibration transmission plate 8 for a time tg corresponding to the distance to the vibration sensor 6, the vibration reaches the vibration sensor 6. The reference numeral 42 in FIG. 4 indicates the signal waveform detected by the vibration sensor 6. The plate wave used in this embodiment is a dispersive wave, so the envelope 42 of the detected waveform
The relationship between 1 and phase 422 changes depending on the vibration transmission distance.

Here, the speed at which the envelope advances is assumed to be group velocity Vg, and the phase velocity is assumed to be Vp. The distance between the vibrating pen 3 and the vibration sensor 6 IIn can be detected from the difference in group velocity and phase velocity.

First, focusing only on the envelope 421, its speed is Vg, and when a point on a certain waveform, for example a peak, is detected as indicated by the reference numeral 43 in FIG. 4, the distance between the vibration pen 3 and the vibration sensor 6 d is d=Vg-tg when nn is tg when the vibration is transmitted.
(1) Although this equation relates to one of the vibration sensors 6, the distances between the other two vibration sensors 6 and the vibration pen 3 can be expressed using the same equation.

Furthermore, in order to determine coordinate values with higher precision, the phase waveform 4 shown in FIG.
22 specific detection points, for example, if the time from vibration application to the zero cross point after passing the peak is tp, then the distance between the vibration sensor and the vibration pen is d=n・Input p + V p @t p ・・
・(2) becomes. Here, input p is the wavelength of the elastic wave, and n is an integer.

From the above equations (1) and (2), the above integral fin is n=(
(Vg-t g-Vp#t p)/λp+l/Nl...
・It is shown as (3). Here, N is a real number other than O, and an appropriate value is used. For example, if N=2 and within the wavelength range, n can be determined.

By substituting n determined as above into equation (2), the distance between the vibrating pen 3 and the vibration sensor 6 can be accurately measured.

' of the two vibration transmission times tg and tp shown in the figure
Since All+ is constant, the waveform detection circuit 9 can be configured as shown in FIG. 5, for example.

In FIG. 5, the output signal of the vibration sensor 6 is amplified to a predetermined level by the amplification 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 timing of the peak of the extracted envelope is detected by the envelope peak detection circuit 53. The peak detection signal is sent to a signal detection circuit 54 composed of a mono-multivibrator or the like to form an envelope 'Il extension time detection signal Tg having a predetermined waveform, and is input to the arithmetic control circuit l.

Further, based on this Tg times signal timing and the original signal delayed by the delay time adjustment circuit 57, the phase 'I!' is detected by the detection circuit 58! A delayed opening time detection signal is formed and input to the arithmetic control circuit l.

That is, it is converted into a pulse of a predetermined width by the Tg multiplied signal monostable multivibrator 55. Further, the comparator level supply circuit 56 outputs t according to this pulse timing.
A threshold value for detecting a p-fold signal is formed. As a result, the comparator level supply circuit 56 is connected to the reference numeral 44 in FIG.
The detection circuit 584 generates a signal 44 having a level and timing as follows.

That is, the monostable multivibrator 55 and the comparator level supply circuit 56 are used to ensure that the phase delay time measurement is activated only for a certain period of time after the envelope peak is detected.

This signal is sent to a detection circuit 5 consisting of a comparator etc.
8 and is compared with the delayed detection waveform as shown in FIG.

The circuit shown below is for one vibration sensor 6,
The same circuit is provided for each of the other sensors. If the number of sensors is generalized to h, then h detection signals each of envelope delay time Tg l -h and phase delay time Tpl-h are input to the arithmetic control circuit l.

In the arithmetic control circuit of FIG. 3, the above Tgl-h, Tpl-
The h signal is input from the input port 15, and the count value of the counter 13 is taken into the latch circuit 14 using each timing as a trigger.As mentioned above, the counter 13 is started in synchronization with the driving of the vibrating pen, so the latch circuit The circuit 14 receives data indicating the respective delay times of the envelope and the phase.

When three vibration sensors 6 are arranged at the positions 31 to S3 at the corners of the vibration transmission plate 8 as shown in FIG. #dl-d3 for the straight line up to the position of the vibration sensor 6 can be obtained.

Furthermore, the coordinates (x,'y) of the position iP of the vibrating pen 3 can be determined from the three-square theorem as shown in the following equation based on this straight line #dl-d3 using the arithmetic control circuit 1.

x, =X/2+ (d 1 + d'2) (d 1 - d2
)/2X...(4) y=, Y/2+ (d l +d3) (di-d3)/
2Y (5) Here, X and Y are the distances along the X and 1' lines between the vibration sensor 6 at the positions S2 and S3 and the sensor at the origin (position Sl).

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

Next, in the above configuration, a correction process for removing the effects of the circuit delay time et and the phase offset time tof in the calculation of the pen-sensor distance and coordinate determination described above will be described.

The vibration transmission time latched by the latch circuit 14 includes a circuit delay time et and a phase offset time tof. The same amount of error caused by these is always included when the vibration is transmitted from the vibrating pen 3 to the vibration transmitting plate 8 and the vibration sensor 6.

Therefore, for example, let the distance from the position of the mark 8a in FIG. 1 to one of the vibration sensors 6 be R, and the vibration transmission time from the mark 8a to the sensor, which is actually
, -tp'r, and the unit from mark 8a to the sensor.
If the transmission time of f is tgr and tpr, these are tg'r=tgr+et (6) with respect to the circuit 8 delay time et and phase offset tof.
tp' r=tgr+et+tof ・-(7)
There is a relationship between

On the other hand, the real J1-values tg'p, tp at any input point P
'p is similarly tg'p=tgP+et...(8
)tp'p=tpp+et+tof −・−(
9), and finding the difference between the two, kg 'p-tg' rm(tgp+et)-(tg
r+et)=tgp-tgr ・-(10)tp'
p-tp'rs(tpp+et+tof)-
(tpr+et+tof)・tpr-tpr
...(11), the circuit delay time et and phase offset (tof) included in each transmission time are removed, and the true distance between the position of the mark 8a and the input point P from the sensor position is The difference in vibration transmission time can be determined.

The distance difference between the two points can be obtained by using the above-mentioned equations (2) and (3) for the time difference value, and the distance giR from the mark 8a to the sensor is already stored in the ROM 1la and is known. Therefore, by calculating the sum of these, the distance between the input point and the sensor can be determined, and furthermore, the above (4)
, (5) can determine the coordinate position.

Correction value tg'r due to vibration input to the position of mark 8a,
tp'r may be obtained at a predetermined timing, for example, immediately after power is turned on, by displaying a message on the display 11' to prompt the operator, or the correction value may be obtained at predetermined intervals during operation. The acquired correction value may be stored in the RAM 1lb.

If the above correction is always performed during operation, changes in circuit delay time and the like caused by environmental changes can be appropriately corrected. However, by taking in correction values at the time of factory shipment and storing the data in a non-volatile memory, it is possible to appropriately correct at least circuit delays and phase offsets that vary from device to device.

In the embodiment described above, it is necessary to measure the delay time at the known position of the mark 8a, and the operator is required to input coordinates accurately to the position of the mark 8a. However, by using the following method, it is possible to input coordinates for inputting correction values at any position.

That is, the coordinates are determined from the hyperbolic function using the delay time difference between the sensors, and the delay time is corrected from the determined value.

Coordinate determination based on the delay time difference is 1. For example, if the sensors are arranged as shown in Fig. 8 and the intersection O of the straight lines connecting the opposing sensors is set as the origin, the difference in distance between the sensors SO and S1 is a, S2
If the difference in distance between and S3 is b, then the indicated point p (x,
y) is hyperbolic as shown in the following equation, but c2=4X2-a2.
d2=4Y2-b2, C2d2-a2b
2>O The coordinates of any input point can be determined by these equations. If the vibration transmission time to each sensor at this time is stored in the RAM Ib as a correction value, the above correction process can be performed.

According to such a method, since it is possible to obtain a correction value at an arbitrary position, even a user can easily perform correction. In addition, if this operation is performed periodically or irregularly at fixed time intervals (for example, when specifying an arbitrary area while inputting coordinates), the correction value can be automatically imported without the user being aware of it. Can be done. Furthermore, it becomes possible to completely correct changes in circuit delay time due to temperature changes and the like.

However, as can be seen from equations (12) and (13), the calculations using a microprocessor are extremely complex, so in terms of accuracy and calculation speed, the above method is not suitable for real-time coordinate determination. method is more advantageous.

However, when a correction value is taken in as in this embodiment, there is not much time limit and the number of digits in calculation can be increased, so it can be used sufficiently for coordinate determination.

It goes without saying that even with the sensor arrangement as shown in FIG. 7, the coordinates can be determined using the Pythagorean theorem as described above.

In the above embodiments, a coordinate input device using plate waves has been mainly described, but the configuration of the present invention is not limited to this, and can be applied to various coordinate input devices using vibration transmission as a medium. Needless to say.

[Effects of the Invention] As is clear from the above, according to the present invention, vibrations input from a vibrating pen are detected by a plurality of vibration sensors provided on a vibration transmission plate, and vibrations inputted from a vibration pen are detected on the vibration transmission plate of the vibrating pen. In a coordinate input device for detecting coordinates, means for measuring vibration transmission time from a predetermined point on the vibration transmission plate to each of the vibration sensors and storing the measured vibration transmission time 1b'l as a correction value; The vibration transmission time from the coordinate input point by the pen to each of the vibration sensors is determined 1111, and the correction value stored in the storage means is subtracted from this measured value to calculate the vibration corresponding to the distance from the predetermined point to the coordinate input point. At the time of transmission 1
111 and performs a calculation based on this time value, the circuit is It is possible to eliminate the influence of delay time and phase offset time, and since the actual correction value is used, there is an excellent effect that accurate coordinate values can be obtained regardless of environmental conditions.

[Brief explanation of the drawing]

Figure 1 shows information input/output using the present invention? Figure 2 is an explanatory diagram showing the structure of the vibrating pen in Figure 1, Figure 3 is a professional diagram showing the structure of the arithmetic and control circuit in Figure 1, Figure 4 is a waveform diagram showing the detected waveform explaining distance measurement between the vibrating pen and the vibration sensor, and Figure 5 is a waveform diagram showing the detected waveform to explain the distance measurement between the vibrating pen and the vibration sensor.
6 is an explanatory diagram showing the arrangement of the vibration sensor, FIG. 7 is an explanatory diagram showing the arrangement of the sensor in a different embodiment, and FIG. 8 is the conventional one. FIG. 2 is a diagram showing problems with the coordinate input device of FIG. l... Arithmetic control circuit 3... Vibration pen 4... Vibrator 6... Vibration sensor 8... Vibration transmission plate 8a... Mark 11... Microcomputer 11 a-ROM 1 l b -・RAM (redemption available) 70.79 of Urasankei A1 exit, Figure 3, A of Ashi, Kuro, Figure 5

Claims (1)

[Scope of Claims] 1) A coordinate input device that detects the coordinates of the vibrating pen on the vibration transmitting plate by detecting vibrations input from the vibrating pen using a plurality of vibration sensors provided on the vibration transmitting plate. means for measuring the vibration transmission time from a predetermined point on the vibration transmission plate to each of the vibration sensors and storing the measured vibration transmission time as a correction value; Measure the transmission time, subtract the correction value stored in the storage means from the measured value to calculate the vibration transmission time corresponding to the distance from the predetermined point to the coordinate input point, and perform coordinate calculation based on this time value. A coordinate input device characterized in that it is provided with a control means for controlling the coordinates. 2) The position of the predetermined point is displayed on the vibration transmission plate, and the operator inputs the coordinates of the predetermined point using the vibrating pen at a predetermined timing.
Coordinate input device as described in Section.