JPS61139822A - Coordinate input device of wireless electromagnetic coupling type - Google Patents

Abstract

PURPOSE:To eliminate band pass filters by detecting the frequency of an electromagnetic wave, to which a moving coil part generates independently, by a phase locked loop (PLL) provided in the fixed detecting part side. CONSTITUTION:When the switch 11 of the moving coil part 15 is turned on, an oscillating circuit 13 is driven by an electric power source 12, and the signal having a prescribed frequency is applied to a coil 14. A voltage induced by a sense line 1 consisting of one-turn fixed coil groups arranged in X and Y directions is amplified by an amplifying circuit 3 and is applied to a PLL 10 and a phase discrimination detecting circuit 4. The PLL10 generates the output whose phase coincides with that of the output of the amplifying circuit 3, and the phase discrimination detecting circuit 4 refers to this output to perform the detection. The detection output is integrated by an integrating circuit 5 to obtain an output corresponding to the fixed coil induced voltage. This output is subjected to A/D conversion by a CPU7 and is inputted thereto.

Description

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

(Prior Art) A conventional wireless electromagnetic coupling type human power device has a configuration as shown in FIG.

The moving coil section 34 connects the switch 30.1 to the source 51.degree. oscillation circuit 32.1. It is composed of a coil 35.

When the switch 50 is turned on, a voltage is supplied from the power supply 31 to the oscillation circuit 32, the oscillation circuit W452 is activated, an AC signal is applied to the coil 56, and an oscillation frequency 'qIJs wave is generated.

When the electromagnetic wave generated from the sq coil 34 approaches the sense line 21, a coil array of one turn is arranged in the X direction and the Y direction, a voltage is induced in the fixed coil of the sense line 21.

This voltage is amplified by an amplifier circuit 25 and then filtered by a bandpass filter 24.
is input.

This bandpass filter 24 selects the signal generated in the oscillation circuit 52 and having a critical wave number.

This signal is transmitted to the detection circuit 25. The signal intensity of the frequency is converted by the integrating circuit 26. The strong signal is converted into a digital signal by the A/D conversion circuit 27, and the signal is converted to a digital signal by the A/D conversion circuit 27.
is input.

Since the CI'U28 selects the coils arranged through the multiplexer 22'f and the sense line 21r,
The coil that generates the maximum intensity can be known, and the coordinate values of the moving coil can be determined from the position of that coil.

Oscillation circuit 29 generates a clock signal for CPO 28.

(The pinnacle of the invention's solution) In the conventional system, it is necessary to match the oscillation frequency of the oscillation circuit 32 and the frequency of the bandpass filter 24. If this frequency matching is not performed, the entire electromagnetic wave detection unit The disadvantage is that the 8N ratio deteriorates and the accuracy of position detection of the moving fill deteriorates.

In addition, the moving coil section 34 needs to maintain compatibility with the electromagnetic wave detection section.6 This is because, if the moving coil section is damaged or lost, it is necessary to be able to input coordinates with the same performance with a new moving coil. 1'b because it has to be done.

In this case, in the conventional method, it is necessary to maintain sufficient firing accuracy of the Qm section 320.

(Means for resolving the problem) In the present invention, the electromagnetic wave detection section side is configured to detect the same wave number of the electromagnetic waves generated in the moving coil. Phased locked loop (
(hereinafter referred to as PLL) generates a signal that is precisely in phase with the electromagnetic waves generated in the coil. Furthermore, by performing phase detection using a phase discrimination detection circuit that uses this signal as a reference signal, the bandpass filter can be removed! 19 is a block diagram of the present invention, moving coil section 15Fi switch 11. Power supply 12゜Motogashi@
Road 13. From Goyle 14, it is grooved.

-t to the oscillation circuit 32 by turning on the switch 11
l(l[31) is supplied, and the oscillation circuit oscillates at a predetermined frequency.

When current is applied to the coil using this signal, the above-mentioned 8
Electromagnetic waves of bottle frequency are generated.

The sense line 1 is a group of fixed coils arranged in a single row in the X and Y directions and each having one turn. to multiplexer 2, CF)
When the controlled analog switch=9, one coil of the fixed coil group is selected, and the output of the coil is connected to the amplifier circuit 5.

The output of the amplifier circuit 3 is connected to the PLL 10 and the phase discrimination detection circuit 4.
is input.

Waveform a! shown in FIG. If is the output waveform of amplifier circuit 3, the output of PLL 1G is in phase with al and 7? : It becomes like a traffic light.

The phase discrimination detection circuit 4 uses the output signal S of the PLL l0 as a reference signal, detects the input waveform a, and outputs the waveform C1. The integrating circuit 5 integrates this C1 waveform and outputs the intensity of the specific induced voltage generated in the fixed coil.

If the output waveform of the integrating circuit 3 is generated from the moving coil and has noise other than a constant signal like C2, then the PLL1
0 means that the frequency t is far off from the free run frequency, the frequency t cannot be locked, and the free run frequency is output.

At this time, the output of the phase discrimination detection circuit 4 becomes like C2.

Integrating circuit 5 outputs zero when cl is input.

The output of the integrating circuit 5 is A/D converted, converted into a digital value, and inputted to the CPt77.

CI) 177 selects which fixed coil and when A/D
The position of the moving coil is detected by determining whether the converted output becomes the maximum, and the position fjt is outputted as the coordinate I.

(Example) FIG. 4 shows an embodiment of the moving coil section 15.

The switch 11t/'i switch 55, the source 12 correspond to the battery 54, the coil 14 corresponds to the coil 52, and everything else corresponds to the oscillation circuit 13.

There are two types of oscillation: self-excited oscillation circuits and separately excited oscillation circuits, but here a frequency-stable crystal is used and externally excited oscillation circuits are used.

In addition, in order to make the moving coil smaller and lighter, 4 crystal coils and 5
The circuit parts other than 1 are compared with engineering C.

7. It is composed of an eid pack resistor 40, a NOT gate 41, capacitors 42 and 45, and a crystal, and the crystal is photographed at a predetermined frequency. Here, 1.2244 MHz is adopted.

This signal is passed through flip-flop 45 to 56144KHS.
Then, the frequency is divided to 307.2 KHz, which is applied to the flip-flop 46.

The output of the flip-flop 45 and the output of the 7-lip-flop 46 are input to the HAND gate 47, and the output of the flip-flop 45 and the inverted output of the flip-flop 460 are input to the HAND gate 48. NA*v of this 2@
The gate output is a 3012KHz two-phase lock signal9.
, coil driving buffer N-0T49,5Of:
The signal is output to the coil 52 via the coil 52.

At this time, the inductance of the coil 52 and the capacitor 51
By setting the capacitance f to have a resonance frequency of 7.2 KH2, a current close to a sine wave flows through the coil 52, and a 307.2 KHz electric wave is generated from the coil 52.

The sense line 1 is formed by etching a double-sided substrate, with coils arranged in the X direction on one side and coils arranged in the Y direction on the opposite side. - Each coil with this sense line is connected to an analog switch, and one coil is connected to the amplifier circuit by a multiplexer controlled by the CPU UK.

FIG. 5 is a detailed diagram of the PLL. VCO (voltage)
- Chondral oscillator) 62f-4, which oscillates with a time constant determined by the built-in resistor and capacitor 62. This rooting frequency is called the free run frequency. The free run frequency is input to an FD (phase detector) 60.

On the other hand, a ratio signal generated from the sense line 1 is input to the PD 60. The PD 60 outputs the phase difference between both waveforms as a voltage. This signal "fr" is passed through an LPF (low pass filter) 61 to convert the phase difference into a DC voltage.

By inputting this signal to the VCO and changing the free run frequency, the output can be made into a signal in phase with the input waveform.

This state is called a locked state.

In order to lock the input signal, the free run frequency must be within a certain range.

This range varies depending on the performance of the VCO, input signal strength, etc., but it is easy to secure it within ±1 (1@).

The accuracy of the oscillator on the moving coil side may be ±10 inches with respect to the time constant that determines the free run frequency. Normally, the crystal generation accuracy is very good, so the free run frequency adjustment precision can be set to -±10 degrees.

Figure 6 shows the phase discrimination detection circuit, and Figure '46 (1!L)
is an example using analog multiplication 4, and FIG. 6(b) is an example using analog switches.

The analog multiplier 64 in FIG. 3 al+'! When inputting the +b waveform, C15C! A waveform of

FIG. 6(b) is composed of analog switches 66 and 67 and a NOT gate 65. Analog switchbar generally p
1! T.) It consists of a transmission gate, etc.

Similarly to FIG. 6(a), if the waveform '1*''Z + b shown in FIG. 3 is input to a and b in FIG. 6(b), the waveform CI
+C3 is obtained.The integrator circuit uses a wide back capacitor from the output of the operational amplifier to the negative input terminal.4 The A/D conversion circuit uses a successive approximation type 8-bit one, and the signal is sent to the CPU. The CPU is a one-chip C
Pυ is used and ROM.

It has built-in RAM, etc.

(Effects of the Invention) According to the present invention, the frequency of the moving coil and the frequency of the filter in the detection section can be matched to approximately #! using the PLL and the phase-discriminative detection circuit. i-adjustment becomes possible9.

Furthermore, the compatibility of the moving coil with respect to the detection unit is enabled.

In addition, the strength against noise visitors can be made the same as that of the conventional wire-bonded type.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the present invention. Fig. 2 is a conventional block diagram @ Fig. 3 is a waveform diagram of the PLL and phase discrimination detection section of the present invention. 419 is a circuit diagram of a moving coil section of the present invention; FIG. 5 is a circuit diagram of the PLL. Figure 6 (&) is No. 1 material discrimination detection circuit used on the analog multiplier. FIG. 6(b) is a t-phase discrimination detection circuit diagram using an analog gate. 1...Sense line (hard ffl coil) 2...
...Multiplexer 4...Phase discrimination detection circuit 5...Integrator circuit 6...Person/D conversion circuit 7...c P, U 10. ...PLL (phased locked loop) 11 ... switch 12 ... power supply 15 ... oscillation circuit 14 ... coil 15 ... ...Moving coil or more

Claims (1)

[Claims] Coordinates in which the coordinates of the moving coil are read by detecting the voltage induced by the magnetic flux generated in the moving coil part in a sense line consisting of a group of fixed coils arranged in the X-axis direction and the Y-axis direction with a voltage detection part. In the input device, the induced voltage detection section configured using the moving coil is configured of at least a phased locked loop, a phase discrimination detection circuit, and an integrating circuit. Device.