JPH0431407B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coordinate detection device for detecting coordinate values of the position of a pointing device on a tablet on which a conducting wire for coordinate detection is laid.

[Conventional technology]

The coordinate detection device detects when a position on the tablet is specified using a pointing device such as an electromagnetic pen or cursor.
This is a device that detects the coordinate values of that position. Such a coordinate detection device is disclosed in, for example, Japanese Unexamined Patent Publication No. 191091/1983 and is well known. The outline of the coordinate detection device described in the publication will be explained below using figures.

FIG. 4 is a block diagram of a conventional coordinate detection device. In the figure, 1 is an oscillator, 2 is a frequency divider that divides the oscillation frequency of the oscillator 1, and 3 is a driver that outputs a sine wave current having the same frequency as the pulse output from the frequency divider 2. Reference numeral 4 denotes an excitation coil built into an indicating device such as an electromagnetic pen, and is excited by the current supplied from the driver 3.

5 is a tablet. The tablet 5 is wired with conductive wires for the X-axis and the Y-axis. The conducting wire for the X-axis consists of four conducting wires, the first conducting wire being wired in a meandering manner at a pitch P, and the second conducting wire being wired at a shift of P/4 with respect to the first conducting wire. Further, the third conductive wire is laid in a meandering manner in the same direction as the first conductive wire at pitch Q, and the fourth conductive wire is laid with a shift of Q/4 pitch from the third conductive wire. If the total number of pitches of the first conductor is n, then pitch P and pitch Q
has the relationship nP=(n-1)Q.

The Y-axis conducting wire is also the same as the X-axis conducting wire except that the wiring direction is different by 90 degrees. 5X and 5Y indicate four conductive wires for the X-axis and four conductive wires for the Y-axis, respectively.

6 is a command signal from a data processing device, which will be described later, to connect a first conductor wire and a second conductor wire for the X-axis, a third conductor wire and a fourth conductor wire for the X-axis, and a first conductor wire for the Y-axis. a second conductor, and a third conductor and a fourth conductor for the Y-axis.
This is a switching device that sequentially switches the conductive wires and inputs the output signal of each of these conductive wires. 7 and 8 are amplifiers that amplify the signal input from the switch 6; 9 is one of the conductors, for example, the first of the first conductor and the second conductor;
10 is an amplifier 8
This is an adder that adds the output signal of the integrator 9 and the output signal of the integrator 9.

A comparator 11 converts the output signal of the adder 10 into a binary signal (pulse signal). A phase comparator 12 detects the phase difference between the rising edge of the output pulse from the frequency divider 2 to the driver 3 and the rising edge of the output pulse from the comparator 11. Reference numeral 13 denotes a data processing device that calculates coordinate values and performs other processing and control based on the phase difference detected by the phase comparator 12.

Now, when a voltage of E ₁ =A ₁ cosωt is applied to the excitation coil 4, the signals output from the amplifiers 7 and 8 (for example, the signals from the first conductor and the second conductor) are respectively E ₁₁ =A ₂ cos (2π・r/P)cosωt E ₁₂ =A ₂ sin(2π・r/P)cosωt. Here, P is the pitch between the first conducting wire and the second conducting wire, and r is the distance from the reference position of the pitch to the position where the pointing device is placed when the pointing device is placed in a certain pitch.

Next, when the signal E ₁₁ is integrated by the integrator 9 and the integrated signal E ₁₁ ' and the output signal E ₁₂ of the amplifier 8 are added by the adder 10, the output signal becomes as follows.

E ₁₁ ′+E ₁₂ =A ₂ sin(ωt+2π·r/P) That is, the signal (E ₁₁ ′+E ₁₂ ) is a phase modulation signal proportional to the distance r. This phase modulation signal is converted into a pulse signal by a comparator 11. The phase comparator 12 detects the phase difference between the output signal of the frequency divider 2 and the output signal of the comparator 11. This phase difference is =2π·r/P. From the above equation, the distance r is r=P·/2π. Here, the phase difference is detected by the phase comparator 12 as follows. That is, the phase comparator 12 is constituted by a counter, and the counter is started at the rising edge of the output pulse from the frequency divider 2, and stopped at the rising edge of the output pulse from the comparator 11. This start and stop period,
When a pulse with a high frequency f ₁ is input from the frequency divider 2 and the number is counted, the number of pulses in the lower diagram is proportional to the phase difference. Similarly, the distance s from the reference position at pitch Q to the indicating device can be determined from the output signals of the third and fourth conductive wires, but in this case, the frequency of the pulse input to the counter is f ₂ (f ₂ = f ₁ ·Q/P).

In this way, when the distances r and s are determined, it is determined at which pitch of the first conducting wire the indicating device is present based on the count values of both. A description of this determining means will be omitted. Once it is determined at which pitch of the first conductor the indicating device is located, the distance r from the reference position of that pitch is known, so the X-axis of the indicating device,
The coordinate value of the Y axis can be determined.

Note that the pulses for counting input to the counter of the phase comparator 12 can be obtained by providing an oscillator within the phase comparator 12 instead of using the pulses of the frequency divider 2. Furthermore, a method has been proposed in which the pitch where the indicating device is present can be determined even when one type of pulse frequency is used for the counting instead of two types (f ₁ , f ₂ ).

[Problem that the invention seeks to solve]

In the conventional coordinate detection device described above, the oscillator 1, frequency divider 2, and driver 3 are provided within the main body of the coordinate detection device, and the excitation coil 4 is provided in a pointing device such as an electromagnetic pen or a cursor. Therefore, the pointing device and the main body of the coordinate detection device must be connected by a wire, and the existence of this wire has caused a problem in that handling of the pointing device becomes extremely troublesome.

In order to solve this problem, it is conceivable that the oscillator 1, the frequency divider 2, the driver 3, and the power source (battery) for supplying current to the excitation coil 4 are all built into the indicating device. However, if the connection between the coordinate detection device main body and the indicating device is completely eliminated in this way, the excitation signal of the excitation coil 4 cannot be input to the phase comparator 12, and the required phase difference cannot be obtained. A situation occurs in which the coordinates are lost and coordinate detection becomes impossible.

SUMMARY OF THE INVENTION An object of the present invention is to provide a coordinate detection device that solves the problems of the prior art described above and can eliminate the wire connected to the indicating device without any problem in coordinate detection.

[Means for solving problems]

In order to achieve the above object, the present invention provides a tablet having a plurality of conducting wire groups each including a first conducting wire and a second conducting wire arranged at a predetermined pitch shifted from the first conducting wire, and an excitation coil. An indicating device that generates a magnetic field by excitation of an excitation coil, and a phase difference obtained from a first signal and a second signal respectively induced in the first conducting wire and the second conducting wire by the magnetic field of this indicating device. a phase comparator that counts the number of pulses input in a corresponding period;
In the coordinate detection device, the coordinate detecting device is equipped with a calculation means for calculating the position of the indicating device above the tablet based on the value obtained by the phase comparator, and the indicating device has all the excitation means for the excitation coil built-in. In addition, each absolute value circuit performs full-wave rectification of the first signal and the second signal, an adder circuit that adds the outputs of these absolute value circuits, and two rectified waves obtained by the adder circuit. A counting start signal output means for outputting a counting start signal for the phase comparator based on the first rectified wave of the waves is provided.

[Effect]

The indicating device has all the means for exciting the excitation coil built-in, and any connection means such as wires for connecting the indicating device to others is eliminated. Therefore, it becomes impossible to obtain the counting start signal of the phase comparator, but the counting start signal is obtained by full-wave rectification of the first signal and the second signal, and adding the respective full-wave signals. It is created using the first signal wave out of two consecutive signal waves. This signal wave is a signal having the same phase as the excitation signal of the excitation coil, and is therefore completely equivalent to the counting start signal in the conventional device, thereby making it possible to construct an indicating device without connection means.

〔Example〕

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 is a block diagram of a coordinate detection device according to an embodiment of the present invention. In the figure, parts that are the same as those shown in FIG. 4 are given the same reference numerals, and description thereof will be omitted.

15 is an indicating device. The indicating device 15 includes an oscillator 1, a frequency divider 2, a driver 3, an excitation coil 4, and a battery 6 (not shown) that supplies current to the excitation coil 4. Further, there is no wire connection between the coordinate detection device main body and the indicating device 15. That is, the pointing device 15 is a wireless pointing device.

16 and 17 are absolute value circuits connected to amplifiers 7 and 8, respectively; 18 is an adder that adds the outputs of the absolute value circuits 16 and 17; 19 is a comparator that converts the output signal of the adder 18 into a pulse signal; 20 is a frequency divider that divides the frequency of the pulse signal output from the comparator 19. The output of frequency divider 20 is input to phase comparator 12.

FIG. 2 shows the absolute value circuits 16, 17 shown in FIG.
2 is a circuit diagram showing a specific example of an adder 18, a comparator 19, and a frequency divider 20. FIG. Absolute value circuit 16, 17
are each comprised of full-wave rectifiers 16a, 17a, respective resistors r, and differential amplifiers 16b, 17b. The adder 18 is configured to connect the differential amplifiers 16b and 17b at a connection point 18a via a resistor r. Comparator 19 is reference voltage source 19
a, a comparator 19b, and a resistor r.
Furthermore, the frequency divider 20D is a flip-flop 20
Consists of a.

The operation of this embodiment will now be described with reference to the wiring diagram shown in FIG. 3a and the waveform diagram shown in FIG. 3b. FIG. 3a is a wiring diagram of the conductive wires of the tablet 5, 21 is the first conductive wire for the X-axis, and 22 is the second conductive wire for the X-axis, both of which are laid out in a meandering manner in the X-axis direction. There are lines. Illustrations of other conductive wires are omitted. The conducting wire 21 is wired at a pitch P, and the conducting wire 22 is wired at the same pitch P with a phase shift of P/4 with respect to the conducting wire 21. Now, among each pitch,
Looking at the second pitch from the left, this pitch starts at line ₂₁₀ in conductor 21. Using this line ₂₁₀ as a reference line, the distance r to the position of the pointing device 15 within the pitch is determined as described above. In the figure, 0, P/4, ……, 7P/4
indicates the distance r with respect to the reference line 21 ₀ .

Figure 3b shows each distance 0, P/4, and distance shown in Figure 3a.
......, when the indicating device 15 is placed at 7P/4, the waveforms of the output signals from each element shown in FIGS. 1 and 2 are collectively shown, and the amplitude of each waveform is as follows. The relative proportions are shown in a size that approximates the actual waveform.

Here, the indicating device 15 is on the reference line ₂₁₀ ,
Consider the case where the excitation coil 4 is exemplified by the sinusoidal excitation signal shown in FIG. 3b.

Assuming that the signals of the conductor 21 and the conductor 22 are inputted by the switch 6, the signal of the conductor 21 is amplified by the amplifier 7, and the signal of the conductor 22 is amplified by the amplifier 8, the column at position 0 in FIG. As shown, the output signal of the amplifier 7 is 0, and the output signal of the amplifier 8 is a sine wave with the maximum amplitude. These signals are input to absolute value circuits 16 and 17, full-wave rectified by full-wave rectifiers 16a and 17a, and then sent to differential amplifier 1.
6b and 17b. In this case, the output of the absolute value circuit 16 is 0, and the output of the absolute value circuit 17 is the third
As shown in Figure b, the full-wave rectified waveform has two consecutive peaks. Therefore, the waveform generated at the connection point 18a of the adder 18 is the same as the output signal of the absolute value circuit 17.

Similarly, the positions of the indicating device 15 are P/4, P/
2,……, the waveform when 7P/4 is the third
Shown in Figure b. No matter where the pointing device 15 is located, the output signal of the adder 18 has a waveform with two consecutive peaks. Note that even when the indicating device 15 is located in the middle of each of the above positions, the output signal of the adder 18 only changes in amplitude, and
There is no change in the fact that the waveform consists of two consecutive peaks.

The output signal of the adder 18 is input to the comparator 19, where it is compared with the reference voltage of the reference voltage source 19a, and from the comparator 19a, as shown in FIG. 2
Two consecutive pulses corresponding to one peak are output. Comparator 1 consisting of these two pulses
The output signal of 9 is input to a frequency divider 20, and the frequency is divided by 1/2 by a D flip-flop 20a. in the end,
The pulse output from the frequency divider 20 is
The pulse has the same phase and period as the excitation signal No. 5. This pulse signal is input to the phase comparator 12, which starts a counter at the rising edge of the pulse signal and stops the counter at the rising edge of the pulse signal from the comparator 11. As a result, from the indicating device 15 to the phase comparator 1
The coordinates can be detected without outputting an excitation signal to 2 by wire.

In this way, in this embodiment, the excitation signal of the indicating device is restored to the same phase and the same wave number by using the signals generated in the two conductive wires wired to the tablet, which are shifted in phase only. , it is possible to eliminate the wire that connects the pointing device and the coordinate detection device main body, and as a result, the pointing device can give instructions without any trouble.

〔Effect of the invention〕

As described above, in the present invention, the signals generated in the two conductive wires wired to the tablet whose phases are shifted are each subjected to full-wave rectification and then summed, and the first of the two signal waves after the addition is Since the counting start signal for the phase comparator is created using the signal wave of This makes it possible to eliminate this problem, thereby making it easier to handle the indicating device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a coordinate detection device according to an embodiment of the present invention, FIG. 2 is a circuit diagram of a part of the device shown in FIG. 1, FIG. 3a is a wiring diagram of a tablet, and FIG. 3b are the waveform diagrams of the output signals of each part shown in Fig. 1, and Fig. 4
The figure is a block diagram of a conventional coordinate detection device. 1... Oscillator, 2... Frequency divider, 3... Driver, 4... Excitation coil, 5... Tablet, 12
... Phase comparator, 16, 17 ... Absolute value circuit, 1
8... Adder, 19... Coparator, 20... Frequency divider.

Claims (1)

[Claims] 1 A tablet having a plurality of conducting wire groups each consisting of a first conducting wire and a second conducting wire arranged at a predetermined pitch shifted from the first conducting wire, and an indicating device having an excitation coil and generating a magnetic field by excitation of the excitation coil. and a first wire guided to the first conductive wire and the second conductive wire by the magnetic field of this indicating device, respectively.
a phase comparator that counts the number of pulses input during a period corresponding to the phase difference obtained from the second signal and the second signal; In a coordinate detection device equipped with a calculation means for calculating a position,
The indicating device includes all excitation means for the excitation coil, each absolute value circuit for full-wave rectification of the first signal and the second signal, and an addition for adding the outputs of these absolute value circuits. A coordinate system comprising: a circuit; and counting start signal output means for outputting a counting start signal for the phase comparator based on the first rectified wave of the two rectified waves obtained by the adder circuit. Detection device.