JPS59186076A - Coordinate input device - Google Patents

Abstract

PURPOSE:To obtain a coordinate signal with high accuracy without being affected with a temperature change and an external magnetic field by exciting a tablet by a burst signal including much of high frequency component. CONSTITUTION:An exciting circuit 6 transmits polyphase burst exciting signals x1-xn and y1-y2 alternately to a tablet 2 via terminals 3-1-3-n and terminals 4-1-4-n respectively at each predetermined period. Further, the circuit 6 transmits a pulse timing signal representing the origin of the X and Y coordinates to a coordinate signal generating circuit 8 in synchronizing with a coordinate signal generating circuit 8. On the other hand, a burst voltage on an input face of the tablet 2 is led to a detecting circuit 7 so as to detect the phase of the fundamental wave. A signal detecting a pulse of a phase representing a coordinate where a pen touches in a magnetic field interlinked with a coil 26 is generated and fed to the circuit 8 accordingly. The circuit 8 counts a required period of clock pulses between the pulse of the timing signal and the pulse of the detecting signal and generates a coordinate signal representing the coordinate of the pen and transmits the signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The coordinate input device of the present invention, in particular, generates electromagnetic excitation that proceeds in the direction of the coordinate axis of the input surface of a tablet, and detects this electromagnetic excitation with a pen to generate an electric signal indicating the coordinates of the pen. Regarding the coordinate input device that occurs.

Conventional 5 A coordinate input device that electromagnetically detects the position of a pen on the input surface of a tablet and generates an electrical signal indicating all the coordinates of the pen, as a means of converting patterns such as characters and figures input by hand into electrical signals. is used.

FIGS. 1(a) and 1(b) are perspective views and time-yards showing a conventional coordinate input device. In the same figure (at), a plurality of magnetostrictive delay lines 13 are arranged in parallel to each other on the upper surface of the substrate 10, and an excitation line 15 is closely attached to one end of each magnetostrictive delay line 13.

Above the magnetostrictive delay line 13, a plurality of magnetostrictive delay lines 14 are arranged parallel to each other and perpendicular to the magnetostrictive delay line 13 via an insulator 11, and each magnetostrictive delay line An excitation wire 16 is tightly attached to one end of the wire 14. An insulating sheet 12 is stacked above the magnetostrictive delay line 14.

Insulating sheet 1 of tablet l constructed in this way
The upper surface of 2 is the input surface.

The excitation lines 15 and 16 are conducting wires for passing an excitation signal of a pulse current to generate magnetostrictive vibrations. Magnetostrictive vibration occurs in the delay line 13 (or 14), and this vibration progresses in the direction shown by the broken line arrow A (or B).On the input surface of the tablet 1 excited in this way, a broken line arrow C appears. When the pen 17 is brought closer as shown, the coil 18 installed inside the pen 17 is between both ends.

A pulsed voltage is induced in response to changes in magnetic flux that occur when magnetostrictive vibrations proceed directly beneath the coil 18. This induced voltage is guided between a pair of terminals 19, and by amplifying and shaping the waveform, a pulse-like detection signal as shown in the figure (bl) is obtained.Excitation of the excitation line 15 (or 16) The time TX (between the pulse of the signal and the pulse of the detection signal)
Or Ty) is the magnetostrictive delay #! This is because it is proportional to the length from the excitation point 13 (or 14) to base 17 on the input surface.

By counting clock pulses of a predetermined period within the time Tx (or Ty) between both pulses, an electric signal (coordinate signal) indicating the coordinates of the shifter 17 can be generated.

In such conventional coordinate input devices, a magnetostrictive delay line is used as an electromagnetic excitation means on the input surface, but the propagation speed of magnetostrictive vibration in the magnetostrictive delay line generally fluctuates greatly with temperature changes. causing errors in the coordinate signal due to changes,
Also, if a magnet is brought close to the magnetostrictive delay line, it will not operate normally.

The drawback is that it cannot be used near devices that generate magnetic fields. Furthermore, the materials for magnetostrictive delay lines are expensive, and in order to align the vibration propagation velocities of each magnetostrictive delay line within strict tolerances, it takes a lot of man-hours to measure and sort the propagation velocities, and to adjust the tension during mounting. The disadvantage is that the cost of this man-hour is added and the device becomes expensive.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inexpensive coordinate input device that eliminates the above-mentioned drawbacks, can obtain highly accurate coordinate signals without being affected by temperature changes or external magnetic fields.

The device of the present invention is configured to transmit first and second excitation signals of a multiphase current for generating the magnetic field from the first and second loop groups for multiple periods. the first one is alternately generated and sent to the tablet;
and an excitation means for generating a reference signal indicating the reference point of the first and second coordinates, respectively, at a predetermined cycle of the second excitation signal, and an excitation means that interlinks with the magnetic field when input to the input surface, and A pen for handwriting input having a detection coil that generates a voltage signal according to a change in a magnetic field, an input detection means that generates a detection signal indicating an input point of the pencil in response to the voltage signal, and the reference. and signal generating means for generating and transmitting a coordinate signal indicating input coordinates of the pen in accordance with a phase difference between the signal and the detection signal.

Next, the present invention will be described in detail with reference to the drawings.

2 and 3 are a perspective view and a block diagram, respectively, showing an embodiment of the present invention. FIG. 2 shows one configuration of the tablet 2 in this embodiment.

In the figure, a plurality of conductor excitation lines 23 and 24 are provided in parallel to each other on the upper surface of the substrate 20, and each excitation line 2
One end of each terminal 3 is connected to a predetermined one of the sequentially arranged terminals 3-1 to 3-n, respectively, by a conductive wire. The other end of each excitation line 23 is connected to one end of a predetermined excitation line 24 by a conducting wire, and the other end of each excitation 1fM 24 is all connected to the terminal 5 by a conducting wire. Each terminal 3-1 to 3-
When an excitation signal ' is input from n, the excitation signal current flows from one end of the excitation line 23 connected to that terminal to the other end, and further passes through the excitation line 24 connected to that excitation line 23 to the terminal. Flows to 5. The current loop of the excitation signal thus formed generates a magnetic field near the top surface of the substrate 20. Excitation line 2
The arrangement positions of terminals 3 and 24 are terminals 3-1 to 3-n.
The phase angle of the alternating magnetic field generated when a multiphase AC excitation signal is input to the excitation lines 23 and 24 is determined to be such that the phase angle changes almost linearly along the direction orthogonal to the excitation lines 23 and 24.

An excitation line forming a loop is provided on the upper surface of the insulating sheet 21 in the same manner as the substrate 20 described above, and one end of each loop is connected to one of the terminals 4-1 to 4-n, and the other end is connected to one of the terminals 4-1 to 4-n. The end is connected to terminal 5. The insulating sheet 21 is stacked and fixed on the substrate 20 so that the elongated loop provided on its upper surface is perpendicular to the elongated loop on the surface of the substrate 20. Even more extreme
An insulating sheet 22 is stacked and fixed on the tablet 21, and the upper surface of the sheet 22 is the input surface of the tablet 2.

In the tablet 2 configured in this way, for example, the terminals 3-1 to 3-n (or 4-1 to 4-n)
When a multiphase alternating current is input as an excitation signal, an alternating magnetic field is generated near the input surface.

The phase angle of this alternating magnetic field is determined between any two points on the input surface with respect to the X coordinate axis (or A difference in size is generated that is approximately proportional to the difference in the X coordinate (or Y coordinate) between the two points. At this time,
As shown by the broken line arrow C, when the tip of the ben 25 is touched on the input surface, an alternating magnetic field interlinks with the coil 26 installed inside the ben 25, and in response, an alternating current voltage is induced between both ends of the coil 26. and is led to a pair of terminals 27.

Note that instead of the multiphase alternating current, a multiphase pulse or a multiphase burst may be used as the excitation signal.

In this embodiment, a polyphase burst is used as an excitation signal. Exciting the tablet 2 with a burst signal containing many high-frequency components has the advantage of increasing the induced voltage in the coil 26, improving the magnetic field detection sensitivity, and reducing the influence of external noise. The tablet 2 that generates a magnetic field in this current loop operates almost unaffected by temperature changes or foreign magnetic fields, and can be manufactured at a low cost.

In FIG. 3, the excitation circuit 6 alternately transmits multiphase burst excitation signals xl to xn and excitation signals yl to yn at predetermined intervals to terminals 3-1 to 3-n and terminal 4-n, respectively. 1 to 4-n to tablet 2. Further, the excitation circuit 6 sends to the coordinate signal generation circuit 8 a timing signal of a pulse whose phase indicates the origin of the X coordinate and the Y coordinate, respectively, in synchronization with the excitation signals xl to Stn and the excitation signals Vl to yn. On the other hand, the burst voltage induced in the coil 26 on the input surface of the tablet 2 is guided to the detection circuit 7 via the terminal 27. The detection circuit 7 amplifies and detects the received burst voltage signal, and then detects the phase of the fundamental wave extracted by the filter.
In response to this, a detection signal of a pulse indicating the phase angle of the magnetic field interlinking with the coil 26, that is, the coordinates of the location touched by the ben 25, is generated and sent to the coordinate signal generation circuit 8. The coordinate signal generation circuit 8 counts clock pulses of a predetermined period between the pulse of the timing signal and the pulse of the detection signal, and generates and sends out a coordinate signal indicating the coordinates of the ben 25.

FIG. 4 is a time chart showing the operation of this embodiment.

The times DI to Dm and the times El to Em are the excitation signals xl to rn and the excitation signals yl to y.
The period is n. The excitation signals rl to Zn and the excitation signals 3'l to yn are both polyphase bursts,
Excitation signals xl to xn indicating the X coordinate of the input surface are alternately sent to the tablet 2 at times DI to Dm, and excitation signals Vl to yn indicating the Y coordinate at times E, l to Em are alternately sent to the tablet 2. The timing signal is the excitation signal x1 and yl
The detection signal is a pulse with a phase that indicates the coordinate origin in synchronization with the coordinate origin, and the detection signal is a pulse with a phase that indicates the coordinates of Ben 25. The phase of the fundamental wave extracted by the filter after detection in the detection circuit 7 shown in FIG. 3 is affected by transient phenomena that occur when the excitation signals rl to 3Cn and the excitation signals 3'l to yn are alternately switched , does not indicate correct coordinates before reaching a steady state.

Therefore, polyphase bursts indicating the X and Y coordinates are alternately sent to the tablet 2 over multiple cycles, and the coordinates are determined by the detection signal at the same gate, where the influence of the transient phenomenon that occurs when switching between the two positions is attenuated to the point where it can be practically ignored. A signal must be generated. In this embodiment, the pulse of the timing signal is sent to the coordinate signal generation circuit 8 only within the last period of time Dm and Em, and the time T: r and Ty until the pulse of the detection signal rises thereafter, respectively. A coordinate signal is generated by counting clock pulses of a predetermined period.

FIG. 5 is a block diagram showing one configuration of the excitation circuit 6 in this embodiment. An oscillator 61 generates a multiphase burst carrier wave and sends it to a branching unit 62 and a switch (8W) 66.

The frequency divider 62 divides the frequency of the burst carrier wave, generates a full first pulse train whose period is l/n of the period of the polyphase burst (where n is the number of phases of the polyphase burst), and divides the burst carrier wave into the frequency divider 62. And send to Ri/Gukau/Ri67. The divider 63 divides the frequency of the first pulse train to generate a second pulse train having the same period as the multiphase burst, and divides the first pulse train into a second pulse train having the same period as the multiphase burst.
Send to 5. The frequency divider 64 divides the frequency of the second pulse train to generate a third pulse train whose period is m times the period of the polyphase burst (m is a predetermined positive integer). The signal is sent to switch 66.

Ring collar/response 67 generates n-phase multiphase pulses in response to the fourth pulse train and sends them to gate circuits 68 and 69.

Each of the gate circuits 68 and 69 has n AND gates, and one phase of the multiphase pulse is applied to each AND gate. The switch 66 is switched to guide the burst carrier wave sent from the oscillator 61 to the gate circuit 68 at the rising edge of the pulse of the third pulse train, and to guide the burst carrier wave to the gate circuit 69 at the falling edge of the third pulse. Let's do it. Therefore, the gate circuits 68 and 69 each alternately generate m periods of multiphase bursts intermittent with the multiphase pulse full burst carrier wave, and each generate the excitation signal 3:1 to Zn and the excitation signal shown in FIG. signal y1
or yn.

The color/return 65 resets to the initial value at each rising and falling time of each pulse of the third pulse train, and then counts the second pulse train to obtain a predetermined count value. When the value is reached, a pulse is generated and sent as a timing signal.

In this way, the burst carrier wave generated by the 1 oscillator 61,
This is successively divided by dividers 62, 63 and 64.
to the third pulse train, the excitation signals El to Zn
By generating the excitation signals yl to yn and the timing signal, it is possible to maintain phase synchronization between these signals and prevent coordinate detection errors and gland movements caused by phase synchronization deviations.

FIG. 6 is a block diagram showing one configuration of the detection circuit 7 in this embodiment. A burst voltage signal sent through the terminal 27 is amplified by the amplifier 71 of the detection circuit 7 and sent to the detection circuit 72.

The detection circuit 72 detects the burst voltage signal sent from the amplifier 71, extracts the fundamental wave component of the detected signal, and sends it to the comparator 73. The comparator 73 generates a pulse that rises when the voltage of the fundamental wave component of the detection signal passes through zero from negative to positive, that is, when the phase angle of the fundamental wave component becomes zero, and this pulse is sent as a detection signal.

FIG. 7 is a block diagram showing one configuration of the coordinate signal generation circuit 8 in this embodiment. The coordinate signal generation circuit 8 receives a detection signal from the detection circuit 7 and a timing signal from the excitation circuit 6.

The time from the rise of the pulse of the timing signal to the rise of the pulse of the detection signal is proportional to the coordinates of Ben 25 with respect to the excited coordinate direction, and the number of pulses of the clock signal within this time is counted. to generate the Shobara signal. First, at the rising edge of the timing signal pulse, the flip-flop (F
F') 82 is set, and the pulse of the signal sent from the output terminal (Q) of FF 82 to color/return 83 rises. Color/return 83 sets the count value to the initial value (zero) at the rising edge of the pulse of the signal sent from the output terminal (Q) of FF8'2.
After resetting to , count the pulses of the clock signal consisting of a pulse train of a predetermined period within the rising time of the pulse of the signal sent from the output terminal (Q) of the FF82,
Send count value signal to latch circuit 84 (0 logical sum) 81
FF at the rising edge of the detection signal sent through
When FF 82 is reset and the pulse of the signal sent from the output terminal (Q) of FF 82 falls in response, the counter 83 stops counting the pulses of the clock signal. On the other hand, when the count value reaches a predetermined value, the color/li 83 (
A signal is generated and sent to the reset terminal (R) of the FF 82 through the OR gate 81. This pulse stops the counting operation of the counter 83 when the count value of the color/receiver 83 reaches a value exceeding the maximum value of each coordinate when there is no pen input on the input surface, and the coordinate indicating the unmanned force is generated. This is for sending a signal from the latch circuit 84. The latch circuit analogy uses the count signal sent from the counter 83 at the falling edge of the pulse of the signal sent from the OR gate 81 as a coordinate signal, and uses the count signal sent from the OR gate 81 as a coordinate signal for the next pulse of the signal sent from the OR gate 81. The excitation circuit 6 shown in FIG. As explained with reference to FIG. 4, it is possible to generate highly accurate coordinate signals without being affected by the transient phenomenon that occurs when switching between the two coordinates.

In this embodiment, the number of phases of the excitation signals x1 to Zn and the number of phases of the excitation signals v1 to yn are made equal to simplify the excitation circuit 6, but there is no need to limit it to this. It is obvious that it is easy to change the number and obtain the same effect as in this embodiment. Further, in this embodiment, the excitation circuit 6 and the coordinate signal generation circuit 8 are constructed of pulse circuits, but the same functions can be realized by program control using a microcomputer, and the same effects as in this embodiment can be obtained. is clear.

FIGS. 8(a) and 8(b) are a partial side view and a characteristic diagram for explaining the relationship between the input surface of the tablet 2 and coordinate signals in this embodiment. As explained in FIG.
This is the top surface of The thickness d of this insulating sheet 22 is determined by the coordinates (input coordinates) when inputting with the pen 25 on the input surface and the value ( (indicated value of the coordinate signal) are experimentally determined to have a substantially proportional relationship.

If the thickness d of the insulation 7-422 is too small, or if the upper surface of the insulation sheet 21 is used as the input surface without providing the insulation sheet 22, the coil 26 will come too close to the excitation lines 23 and 24. In the vicinity of the excitation lines 23 and 24, the proportionality between the input coordinates and the indicated value of the coordinate signal is good, but in other places, the proportionality between the two deteriorates, as shown by the broken line H in Figure (b). Then, excitation wins 23 and 24
A deviation from the proportional relationship occurs for every pitch p in between, resulting in a wavy characteristic curve. As described above, by setting the insulating sheet 22 to an appropriate thickness d and using its upper surface as the input surface, the input coordinates and the indicated value of the coordinate signal can be substantially changed as shown by the solid line G in FIG. The input surface can be configured to form a proportional relationship with an error less than a predetermined resolution, and highly accurate coordinate signals can be obtained.

As is clear from the above description, the present invention has the effect of realizing an inexpensive coordinate input device that can obtain highly accurate coordinate signals without being affected by temperature changes or external magnetic fields.

[Brief explanation of the drawing]

FIG. 1 (ai and b) is a perspective view and time chart showing a conventional coordinate input device, FIG. 2 is a perspective view showing an embodiment of the present invention, FIG. 3, FIG. 5, FIG. FIG. 7 is a block diagram showing an example of the invention, FIG. 4 is a time chart showing an embodiment of the invention, and FIGS. 8(a) and (b) show an embodiment of the invention. Partial side view and characteristic diagram 0 1.2... Tablet, 17.25...
・Pen, 18.26... Coil, 21, 22.
...IPL edge cool. 23.24...Excitation line, 6...Excitation circuit, 7...Detection circuit, 8...Coordinate signal generation circuit, 61...・Oscillator, 62-64...
...Frequency divider, 65.83 ...Counter, 66
...Switch, 67...Ring counter, 68, 69...Gate circuit, 71...
...Amplifier, 72...Detection circuit, 73...
... Comparator, 81 ... OR gate, 82.
...Flip-flop, 84...Latch circuit. Ax figure 1 figure 2 figure 7 ((j)

Claims (1)

[Claims] a tablet having an input surface provided thereon; and a first and second excitation signal of a multiphase current for generating the magnetic field from the first and second loop groups, which are alternately generated in multiple cycles and sent to the tablet. an excitation means for generating a reference signal indicating the reference point of the first and second coordinates at predetermined periods of each of the first and second excitation signals; A pen for handwriting input having a detection coil that interlinks with a magnetic field and generates a voltage signal according to a change in the magnetic field, and an input detection device that generates a detection signal indicating an input location of the pen in response to a distribution voltage signal. A coordinate input device comprising: a coordinate input device; and a signal generating device for generating and transmitting a coordinate signal indicating input coordinates of the pen according to a phase difference between the reference signal and the detection signal.