JPS61139821A - Coordinate input device of electromagnetic coupling type - Google Patents

Abstract

PURPOSE:To reduce the number of cables to a moving coil to two wires by turning on/off a diode in the moving coil, switching over between a fundamental wave and harmonic and detecting an induced voltage in a fixed coil by phase discriminating detection. CONSTITUTION:A waveform synthesizing circuit 8 gives coil driving signals (e) and (f) to an AC driving circuit 10 on the basis of a timer signal (d) and a fundamental wave harmonic switching signal (g) given from a CPU7 to drive a moving coil part 14. When a switch 12 is turned off, these signals are inputted directly to a coil 13; and when it is turned on, they are rectified by a diode rectifying circuit 11 to input the fundamental wave and harmonic. A signal induced by a sense line having the fixed coil passes an amplifying circuit 3 and is detected in a phase discrimination detecting circuit 4 by a reference signal (b) given from the waveform synthesizing part 8. The detection output is integrated by an integrating circuit 5 to obtain an integral output corresponding to the switch operation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a coordinate input device used for inputting coordinate information required in CAD and the like.

(Conventional technology) Conventionally, the configuration shown in FIG. 2 has been used.

The signal generated by the oscillator circuit 29 provides the cpozalC clock and the internal #! signal to 0PT32B. Provides a reference signal for the timer circuit. The wave synthesis circuit 50 generates a signal for fully driving the coil 34 from the signal output from the timer circuit and via the flow circuit 31. Synthesize.

The moving coil section 35 includes a coil 34 and a switch 35. 0N10 of switch 55? ? No. 4 indicates that the detection circuit 52 is manually disconnected by one end of the coil g movement signal and the switch line in order to reduce the number of signal lines to the moving coil section 35.
It is input to Fυ28.

One turn of coil row is 1. The sense line 2171) /L/ formed in the Y direction is selected from the FO 28 via the multiplexer 22 and connected to the amplifier circuit 23.

The amplified signal at this time is passed through the bandpass filter 24, the detection circuit 25. Integrating circuit 26, A/D-converter 27 via gold 0F0
28.

0F028 is coil 3 when which sense line is selected.
The coordinate position *1 of the moving coil can be determined by calculating whether the signal driving the moving coil generates an ant-large induced voltage.

(Problems to be Solved by the Invention) In an electromagnetic coupling type coordinate input device, the moving coil portion 35 and C
A V connection is made between the Pt1 sides by a cable.

It is originally desirable to remove this cable, and ideally the coil part can be moved freely, but in the case of an electromagnetic coupling type, at least two cables are required for driving the coil. In order to further improve operability, at least three switches are required in the moving coil.

In the present invention, the number of cables to the moving coil with switch is reduced to 2.
I was able to make it into a book. This makes it possible to make the cable to the moving coil thinner and softer.
It is possible to provide comfortable operability in a coordinate input device where operability is an important point.

(Means for solving the problem) In the present invention, the cable to the moving coil section is
In order to be configured with a book, a switch, guide, and ode are built into the moving coil section. Switch tON10IF'
By F', diode '1ON10 is added to the coil.
FFL, 1. x, it fONwPKd outputs harmonics from the coil k.

For this reason, a phase-discriminative detection circuit is used in the circuit section that detects the induced voltage generated in the fixed coil, and the frequency of the reference signal applied to the phase-discriminative detection circuit is changed to detect both the fundamental wave and harmonics. The presence or absence of this harmonic signal can be determined by turning the switch ON/O
It becomes an FF signal.

By using such a detection method, it was possible to reduce the number of cables to the moving coil to 72 without complicating the entire circuit.

(effect) The present invention is constituted by the block diagram shown in FIG.

It provides a clock signal for the signal UOFD7 generated by the oscillation circuit 9, and also serves as a reference signal for the built-in timer circuit.

The signal d generated by the timer circuit is input to the waveform synthesis circuit 8, and the signal d is synthesized into a coil drive signal.

Further, a fundamental wave and harmonic switching signal g is inputted and combined into a reference signal b1 to be sent to the phase discrimination detection circuit 4.

Coil drive signals e and f are input to the moving coil section 14 via the AC drive circuit 10.

This signal is input directly to the coil 15 when the switch 12 is OFF, but when the switch QON is turned on, it is rectified by the rectifier circuit 11 composed of diodes, and the coil 13 is inputted into the fundamental wave component and even harmonic components. Driven.

The sense line 1 has a large number of fixed coils each having one turn arranged in the X direction and the Y direction. One coil of this one-turn coil group is connected from 0FD7 to multiplexer 2't-
is selectively connected to the amplifier circuit 3.

The output signal a of the amplifier circuit is inputted to the phase-discriminative detection circuit 4, and a transverse wave of the signal matching the frequency of the reference signal A is generated.

FIG. 3 is a waveform diagram of this phase differential detection.

aIill, fundamental wave, I! Lt is twice the harmonic.

The phase discrimination detection is performed using a multiplication circuit shown in FIG. 5(a).

Alternatively, it may be configured with a transmission gate or an analog switch using FBTi, as shown in FIG. 5(b). Therefore, when altam is input to the phase discrimination detection circuit and the reference signal has the same frequency as the fundamental wave shown in bl, the output signals are respectively.

OII * Becomes like Oll. Integrating circuit 5 for Oll's signal? When passed, a signal proportional to the amplitude is obtained, but 01
When a signal of 1 is input to the integrating circuit 5, the output signal becomes zero. Also, in the same way as when the noise component signals rt: and alt' are input, they become zero by passing through an integrating circuit.

Further, when a signal having twice the fundamental wave as the reference signal kbt is used, the output of the phase discrimination/detection temporary circuit 4 becomes OH when al is input, and CWt when az' is input. 01
When a signal of 1 is input to the integrating circuit 5, its output is zero, c
When all the signals of tt are input, the output of the integrating circuit 5 is an electric current i proportional to the amplitude.

In this way, the switch operation of the moving coil section is obtained as the output of the integrating circuit 5. This signal is input to the A/]) conversion circuit 6, converted into a digital signal, and input to OF[]7. 0Pt17 can know the coordinate value of the moving coil by knowing the entire position of the fixed coil where the maximum value of the fundamental wave was detected. It is also possible to perform harmonic detection only when the maximum value is detected. Also, the maximum value of the fundamental wave,
19. Taking the ratio of harmonic heights. It is also possible to distinguish noise from signal sources other than the moving coil, and more reliable switch input detection is possible.

(Example) Embodiments of the block diagram of FIG. 1 are shown from FIG. 4 onwards.

FIG. 4 shows an embodiment of the AC drive circuit 10 and the moving coil section 14.

The output of the coil drive buffers 50 and 51 is the moving coil section 1.
4 is output.

The coil section 14 has a coil etc. mounted in the shape of a pen, and the center of the coil is equipped with a pen tip 57, and when the pen tip 57 is pressurized, the switch state of the switch 52 changes.

Drive buffer 50,! The output of M is connected to coil 54 under normal conditions. The coil 57 generates an electromagnetic wave close to a sine wave by matching the resonance frequency determined by the inductance of the coil and the capacitance of the capacitor 55 parallelly connected to the coil with the total driving frequency.

When the pen tip 57 is further pressurized and the switch 52 is switched, a diode 54 is connected in parallel with the coil 56, and a diode 53 is connected in series. Therefore, since only one direction of current flows through the coil 56, even harmonics are applied to the coil in addition to the fundamental frequency.

Therefore, the moving coil section 14 outputs electromagnetic waves of the fundamental wave and even harmonics.

FIGS. 5(a) and 5(1)) show the phase discrimination detection circuit 4. FIG.

FIG. 5 (&) is a multiplication circuit, which has the output a of the amplifier circuit applied to one direction of input, and the frequency signal used for driving the coil applied as a reference signal to the other direction.

When the reference signal is a square wave, the product of both waveforms is O shown in Figure 3.
l Or 0! The waveform will be

Figure 5(b) shows the transmission gate.

A phase-discriminative detection circuit using an analog switch realized by 7vT:9 is shown.

The output signal of the amplifier circuit 3 is applied to the signal b, and the reference signal is applied to the signal b.

When the reference signal is 1H'', the analog switch 62 is OFF.
When the waveform a is output at L, the analog switches 62uOFF' and 63 are turned ON when the output is @L', and the output becomes the voltage divided by the resistor 59.60.

FIG. 6 shows an embodiment of the waveform synthesis circuit 8.

FIG. 7 is a waveform diagram of FIG. 6.

A 1.2288 MH2 square wave d is output from the built-in timer of OPυ7 and input to the flip-flop 70.

The output Q of the flip-flop 70 is 614.4 KHz, and the signal is input to the flip-flop 710.

The output of 10 is a signal of 307.2 KHz.

The AND gate 72 has the output of the flip-flop 70, 71 -AND gate) 731/(is the flip-flop 70)
and i of 71 are input, and the output q of gate 6 is
If f is the signal e-f applied to the coil, the signal e-f will be as shown in diagram M7.

A phase shift is performed in the shift register 78 using a 3012 Hz signal and a 1.2288 MHz clock.
Obtain the bI waveform shown in the tgs diagram.

Further, the output of the flip-flop 70 is a b10 waveform shown in FIG.

The output g from OFt+7 is input to the AND gate 74. When @H'', the output b of the OR gate 76 is selected as bI.

When g is @L #, H1 is input to AND gate 75 because it is through NOT gate 77t, and OR
The output of gate 76 is selected.

A general operational amplifier is used for the amplifier circuit.

By cutting this portion of the 8f low frequency, the 8N ratio can be further improved.

The integrator circuit consists of an operational amplifier and a capacitor.
The detection outputs of 07.2KHz and 6144KH2 are completely smoothed.

The A/D conversion circuit is 8bLf; all the ones from i-order comparison shop are used.

OF 07tdr) ROM, RAM in 7f knob 0Ftl
It has a built-in and outputs coordinate value signals from the output boat.

Senseline uses a double-sided printed circuit board.

On one side! 1 coil row in the direction, 1 coil row in the Y direction on the other side
A row of tan coils is formed by etching, and each coil is connected at one end to ground and to the amplifier via an analog switch. The analog switch is F-selected by the multiplexer.

(Effects of the invention) Cable f to the moving coil part: By making the cable f: 2, the work 9 cable can be made softer and thinner, which significantly improves operability, and reduces cost by reducing the number of connectors to the moving coil part. It went down.

Although the number of diodes has increased as a factor in cost increase, it is insignificant. In addition, the circuit section does not have parts such as coils, so it is
It is a circuit that can be easily converted into C and does not result in an increase in cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram relating to the present invention. FIG. 2 is a block diagram related to the conventional invention. FIG. 3 is a waveform diagram of the main part of the present invention. FIG. 4 shows an embodiment of the moving coil section of the present invention. FIG. 5(a) is a diagram of a phase discrimination detection circuit using a multiplication circuit. FIG. 5(1)) is a phase discrimination circuit diagram using an analog switch. Figure 6 shows an example of a waveform synthesis circuit. FIG. 7 is an input/output signal waveform diagram of the waveform synthesis circuit. 1... Sense line fixed coil 4... Phase discrimination detection circuit 5... Integrating circuit 11... Rectifier circuit 12... Switch 15... Coil 14... Moving coil section 7... 0Ft1 Applicant: Seiko Electronic Industries Co., Ltd. Figure 3, Figure 4, Figure 5 (a) Figure 5 (b) Figure 6

Claims (2)

[Claims] (1) In a device that detects the position of the moving coil based on the electromagnetic coupling strength between the fixed coil and the moving coil and outputs the coordinate values of the coil as an electrical signal, the moving coil section consists of a rectifier, a switch, and a coil. The induced voltage detection section includes at least a phase discrimination detection circuit using a reference signal and an integration circuit, and is configured to detect ON/OFF of the moving coil.
An electromagnetic coupling type coordinate input device characterized in that OFF is detected by changing the reference signal. (2) The electromagnetic coupling type coordinate input device according to claim 1, wherein the switch has two cables connected to the moving coil section.