JPH01113822A - Coordinate detector - Google Patents

Abstract

PURPOSE:To detect the coordinate positions with high accuracy by setting 3rd and 4th lead wires with a shift secured by 1/8-pitch against 1st and 2nd lead wires and obtaining the real value from the phase modulated signal value obtained at selection of a pair of 1st and 2nd lead wires and a pair of 3rd and 4th lead wires to obtain the coordinate position from said real value. CONSTITUTION:A 3rd lead wire 101 is set with a shift secured by p/8 to a 1st lead wire 1 and in the same size and same form as the wire 1. While a 4th lead wire 102 is set in the same direction as a 2nd lead wire 2 with a shift secured by p/8 secured to the wire 2 in the same size and same form as the wire 1. A phase error (pi=180 deg.) is secured between the cycle of the error included in the phase modulated signal value obtained at selection of a pair of wires 1 and 2 and the cycle of the error included in the phase modulated signal value obtained at selection of a pair of wires 101 and 102. Thus it is possible to obtain the real phase modulated signal value by cancelling the cyclical error by means of said both phase modulated signal values. Therefore the coordinate positions can be detected with high accuracy by obtaining the coordinate value of an energizing device based on the real value of the phase modulated signal.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention generates an alternating current magnetic field signal from an excitation device such as a coil installed in a coordinate indicating device such as a pen or a cursor, and generates an alternating current magnetic field signal that is arranged in parallel. A device (hereinafter referred to as a coordinate system) that detects the indicated coordinate position of an excitation device by applying an AC signal to a tablet having an electric conductor wire (hereinafter referred to as a conductor wire) and detecting an alternating current signal induced in a matrix-shaped conductor wire equipped on the tablet. (collectively referred to as a detection device).

[Conventional technology] Generally, the coordinate detection device is a pen or a cursor.

This pen or cursor is equipped with a device that supplies a sine wave voltage to a coil, a tablet that is equipped with an X-axis base and a Y-axis base on which detection conductors are arranged, and a device that supplies signals generated in the detection conductors. It consists of a device that calculates the position (X coordinate position, X coordinate position) on the tablet where the arithmetic processing pen or cursor is placed.

FIG. 7 is an explanatory diagram of a conventional X-axis layer base.

The X-axis layer base shown in FIG.
8. A conductive wire 1 drawn as a solid line alternately connects both ends of partial conductive wires 5, 6.7 arranged adjacently in parallel with connecting wires 8, 9.
The conductor wires 5, 6, and 7 of the parallel parts are connected at constant intervals (p
/2).

A conductive wire 2 drawn with a broken line has the same shape as the conductive wire 1, and is shifted by p/4 with respect to the conductive wire 1. This 2
The two conductive wires 1 and 2 are stacked in a sheet-like manner while being electrically insulated from each other.

In addition, 11.11 indicates the output terminal of conductor 1, and 12.12
indicates the output terminal of the conductor 2.

Now, place the excitation device IO on this X-axis base and excitation device 1
When an alternating current signal of a predetermined frequency is supplied to the wires 1 and 2, the signals Eyu, . It is determined by the position X in the direction perpendicular to the conducting wire. If the exciter 10 is excited with an AC signal of 8k)lz, for example, and the center of the coil of the exciter 10 (the center of the exciter 10) is placed directly above the conductor 1, the output of the conductor 1 The voltage is 0. The center of the excitation device 10 is located between the partial conductors 5 and 6.
When placed between terminals 11 and 11 or at the center between 6 and 7, the maximum voltage appears between terminals 11 and 11, but its polarity is
The partial conductors between 5° and 6 and between 6 and 7 are reversed. The output voltage obtained between terminals 11 and 11 is, for example, 8kHz.
This is an amplitude modulation jJ5 force that modulates the amplitude (Fig. 8 (A)) using an AC signal as a carrier signal, and the modulated output changes to a sine wave shape or a cosine wave shape depending on the position where the excitation device 10 is placed. do. This is because the partial conductors 5, 6.7 of the conductor 1 are arranged at every electrical angle π. Hereinafter, the interval corresponding to 2π in electrical angle (p in FIG. 7(A)) will be referred to as one pitch.

FIG. 7(B) shows a second X-axis layer base used to overlap the aforementioned X-axis layer base. This second X-axis layer base is provided with conductive wires 3 and 4 .

The relationship between the conductors 3 and 4 is the same as the relationship between the conductors 1 and 2 described above, but in the conductors 3 and 4, 1 pitch is 9 (≠p)
They are arranged with a shift of q/4 from each other. Comparing conductor 1 and conductor 3 in the example of Figure 7, conductor 1 has a total length Q of 5.
In contrast, the conductive wire 3 is divided equally into four pitches. That is, the relationship is Q=5p=4q. in general.

If the number of pitches of the conductor is n, then ff=np=(n-1)
It is convenient to choose the relationship of q, but it is not limited to this. Between the output terminals 13 and 13 of these conductors 3 and 4 + 14.
Signal E engineer that appears between 14 and 1. E14 is shown in FIG. 8(B). The output signals of the conductors 3 and 4 have a sine wave shape as shown in FIG. 8(B), as in FIG. 8(A).

Although it has a cosine wave shape, the period differs by the difference in length of one pitch.

The excitation device 10 is placed on the X-axis output base to obtain the output signal of the conductor 1°2, and from this signal it is possible to determine only the position of the excitation device 10 between the partial conductors 5 and 6.7. However, it is not possible to determine how far away from the reference position @R the partial conductor 5, 6.7 is. This is because the output signals of the conductors 1 and 2 are periodic signals. Therefore, a signal with a different period (Fig. 8 (B)) is obtained from the second X-axis layer base, and the arrangement position of the excitation device IO with respect to the reference position R is determined from the output signals of the conductors 1, 2, and 3.4. be. Instead of this second X-axis layer base, it is also possible to use a coordinate area detection base in which selector conducting wires are arranged in a grid pattern, as described in Japanese Patent Publication No. 53-34855, for example.

Incidentally, there are Japanese Patent Application Laid-open Nos. 58-191091 and 1987-159191 as related to conventional coordinate detection devices.

[Problems to be Solved by the Invention] When the excitation signal E1=A1cosωt is applied to the excitation device, the output signal E1□ of the first conductive wire and the second conductive wire.

El, is theoretically E11=A, cos (2tc llr/p) cos
w tE12=A, sin (2π0r/p) cos
However, in reality, the amplitude due to the position r is not a perfect cosine wave or sine wave, but has distortion. That is, in the above equation, r=J is exactly r to J. Therefore, for example, when using the second X-axis circumferential base described above, the reference position R
Taking as an example a method for determining the moving position r from to the position of the excitation device on the tablet, the phase modulation signal E, which is proportional to the moving position r, is theoretically E. =/E engineering, dt+E engineering.

=A, sin ((11t+2π・r/p) is actually E,.=A*f(r/p)sin(c,+t+2 x
・r/p +f(r)) 6 In other words, both the amplitude and the two phases are functions of the position r, and the phase modulation signal E1° includes a periodic error. This means that the detected X and Y coordinate positions include periodic errors, and
.

This is a factor that hinders detection of the Y-coordinate position.

An object of the present invention is to provide a coordinate detection device that eliminates the above-mentioned periodic errors and makes it possible to detect coordinate positions with high precision.

[Means for Solving the Problems] The above object is to provide an oscillation circuit, an excitation device excited by the oscillation circuit, and a meandering first conductor wire in which parallel conductor portions are arranged with one pitch being an electrical angle of 2π. 1 with the second conductor
The coordinate position of the excitation device is determined from the signals induced in the first conductive wire and the second conductive wire when the excitation device is placed on the tablet and excited by placing the base for the coordinate axes arranged 74 pitches apart. In the coordinate detecting device, the coordinate detecting device includes means for generating a phase modulation signal according to the first. A third conductor having the same dimensions and shape as the second conductor. Connect the fourth conducting wire to the first. are arranged on the tablet at a 1/8 pitch shift with respect to the second conducting wire pair, and the data processing device calculates the phase modulation signal value obtained when the first and second conducting wire pair is selected, and the third conducting wire pair. ．． This is achieved by determining the true value of the phase modulation signal value from the phase modulation signal value obtained when the fourth conducting wire pair is selected, and determining the coordinate position of the excitation device from this true value.

[Effect] 1st. The period of error included in the phase modulation signal value obtained when the second conductor pair is selected, and the period of error included in the phase modulation signal value obtained when the third and fourth conductor pair are selected. are out of phase by π=180°. Therefore,
The true value of the phase modulation signal value can be obtained by canceling the periodic error using the plane phase modulation signal value. If the coordinate position of the excitation device is determined based on the true value of this phase modulation signal, the coordinate position can be detected with high precision.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 7. In addition, in the embodiment described below, in addition to the first X and Y axis circumferential bases, the second X described above is used.

Y-axis circumferential base (1st and 2nd Y-axis circumferential bases are 1st and 2nd
The X-axis peripheral base of is physically rotated by a predetermined angle, for example, 90'. ) This is a case in which the stacked objects are used as a tablet, but it goes without saying that the present invention can also be applied to a coordinate detection device using a coordinate area detection base provided with a selector conducting wire.

FIG. 1 is a plan view of an X-axis base according to an embodiment of the present invention. This X-axis base has a spacing of parallel conductor parts of ρ/
In addition to the first conducting wire 1 having a meandering shape and the second conducting wire Jtlt2 having the same size and shape as the first conducting wire 1 and being shifted by p/4 with respect to the first conducting wire 1, first conductor 1
A third conducting wire 101 having the same dimensions and the same shape as the first conducting wire 1 and shifted by p/8 with respect to the first conducting wire 1; and a fourth conducting wire 102 which is shifted by p/8 in the same direction. Similarly, there is a third section on the Y-axis base (not shown).
A fourth conducting wire is provided.

FIG. 2 shows a coordinate detection device equipped with a tablet that integrates the X-axis base shown in FIG. 1, the second X-axis base shown in FIG. 7(B), and a first and second Y-axis base (not shown). FIG. In the figure, numeral 17 is a high frequency clock oscillator, and numeral 18 divides the clock signal into a predetermined frequency.

The output of the counter 18 is passed through the filter 19 to the exciter 1
0 and is simultaneously applied to the comparator 20.

Reference numeral 21 denotes a tablet configured by overlapping a first X-axis base, a second X-axis base, a first Y-axis base, and a second Y-axis base, and this tablet 21 has an X-axis output terminal (first .2nd.3rd.4th conducting wire L, 2, 101
．． 102 output terminal) 21a, Y-axis output terminal (output terminal of each of the first, second, third, and fourth conductors, not shown)
21b, and both output terminals 21a and 21b are connected to a switching circuit 22. 22 is a time division switching circuit that selects an input at a predetermined period and switches the connection relationship with an amplifier 23 or 24, which will be described later. 23 and 24 are amplifiers, and 25 is an integrator connected to the amplifier 23.

26 is an adder that adds the outputs of the amplifier 24 and the integrator 25. A converter 27 converts the output (sine wave) of the adder 26 into a rectangular wave, and the rectangular wave signal is applied to the comparator 20 together with the output of the counter 18. The comparator 20 compares the phases of the reference signal (rectangular wave) from the counter 18 and the rectangular wave signal from the converter 27, and outputs a detection signal corresponding to the phase difference. In the detection signal, the phase difference is expressed in a signal form such as a pulse width, a voltage value, a number of pulses, or a numerical signal.

28 is a data processing device which takes in the phase difference signal data from the comparator 20 and calculates the coordinate values of the excitation bag [10] placed on the tablet 21. FIG. 3 shows a specific circuit configuration. In this figure, the same reference numerals as in FIG. 2 indicate the same parts. The switching circuit 22 has two time division switching circuits 29 and 3.
0 and its output signal is applied via transformers 31 and 32 to operational amplifiers 33,34. 35.36 is operational amplifier, 37.38 is capacitor, 39.40.41
．． 42 and 43 are resistors. 44 is a waveform converter 27
The output voltage of the DC power supply 45 is adjusted by a variable resistor connected to one side input terminal of the operational amplifier 36 that constitutes the DC power supply 45. 4
6 is a flip-flop which is set by the rectangular wave signal from the counter 18 and reset by the signal from the waveform converter 27. 47 is a counter and flip-flop 46
output, that is, a time corresponding to the phase difference between the reference rectangular wave signal and the signal from the waveform converter 27.

By a high frequency clock signal from clock signal generator 17. Interpolate (count).

Note that the comparator 20 may be a latch circuit constituted by a D flip-flop or the like, and even if the output of the counter 18 is latched by the output of the waveform converter 27, the phase difference between both signals can also be detected. This detection method uses counter 18
It is necessary that the phase of the output of the excitation device 10 and the phase of the excitation current of the excitation device 10 have a constant relationship. Since many circuit configurations for detecting the phase difference between two signals are already known, it is appropriate to select a usable one from these. In the data processing device 28, either a method of calculating the position of the excitation device IO using an arithmetic expression or a method of finding the position of the excitation device 10 by searching using a data table prepared in advance can be adopted. The operation of the data processing device 28 will be described below based on the following specific numerical examples.

Numerical example Total length Q = 100mm To make the explanation of this example easier to understand, the counter 18
Since both the X-axis base and the Y-axis base have the same function, the X-axis base will be explained. When 1000 clock pulses are made to correspond to the pitches p and q on the first conductor and the second conductor, respectively, the pitch P+q and the contents of the counter 18 become as shown in FIG. The resolution is 0.02 mm per pulse on the first conductor (base) and 0.025 mm per pulse on the second conductor (base). The circle mark indicates the arrangement of the first conductor (
At a distance of 20 mm), white blanks and black blanks indicate adjacent conductors (current direction is opposite). Similarly, the triangle mark indicates the location of conductor 3 (
White blanks and black blanks indicate adjacent conductors with a spacing of 25 nm). The signal passes through an excitation router 19 and becomes an excitation signal. Excitation device 1
The excitation signal emitted from 0 induces an alternating signal (hereinafter referred to as a carrier signal) having the same frequency as the excitation signal at the base of the X-axis of the tablet 21. This carrier signal is amplitude modulated depending on the position of the exciter 10.

The method of amplitude modulation is as explained in Fig. 8,
This modulated signal is obtained from the output terminal 21a from the X-axis base. In the switching circuit 22, the output E x t from the conductor 1 is integrated by the integrator 25 via the amplifier 23 and input to the adder 26, and then the output E x t from the conductor 2 is added via the amplifier 24. input into the device 26. Adder 26
Signal E work added by. is obtained by converting the amplitude modulation of a carrier signal into phase modulation of another carrier signal, and this signal E1° is waveform-converted by a waveform converter 27 and then applied to a comparator 20. The signal E1o is compared in phase with the reference rectangular wave signal from the counter 18 and converted into a data signal EL having the number of pulses F1 according to the phase difference. The number of pulses F1 of this data signal E26 corresponds to the amount of displacement r when the excitation device 10 is placed at position a in FIGS. 7, 8, and 4. Similarly,
At the next timing, the switching circuit 22 outputs the output E from the conductor 3.
The output EL4 from the conductor 4 is integrated by the integrator 25 via the amplifier 23 and inputted to the adder 26.
4 to the adder 26. The signal E□ added by the adder 26 is waveform-converted by the waveform converter 27 and then applied to the comparator 20. The signal E is compared in phase with the reference rectangular wave signal from the counter 18, and the data signal E has the number of pulses F depending on the phase difference. is converted to This pulse number F corresponds to the displacement amount S shown in FIG. 7(A).

In the data processing device 28, data signals E are input in a time-division manner. ,E. The position X of the excitation device 10 is calculated from the relationship with the pitch number m. Data signal E! from comparator 20! . The number of pulses F1 has periodicity between the number of pulses O and 999 according to the change in the position X (0-J, -J, -J3-J, -J, in Fig. 4), and 1
By determining whether it is larger or smaller than (up to 500 pulses), it is possible to determine within which pitch of the conducting wire 1 the excitation device 10 is placed. In other words, F engineering>
F.

If ΔF:F1-F, ,F, if <F2 then ΔF=F+
ΔF, which becomes F, −F, is defined by calculation. As shown in FIG.
-K, -K, -K4), the pulse number has periodicity between O and 999. This data signal E,.

Letting ΔF be the difference in the number of pulses between
Varies between ~999. The number of pitches m on which the excitation device 10 is placed is determined based on the number of pulses of this data ΔF.

Table 1 shows the structure of data for determining the pitch number m.

According to Table 1, the exciter 1 is located at point a in FIG.
If 0 is placed, data ΔF is 350 and F
Since l is 750, 500≦F 1 (corresponds to 1000, so the pitch number m is 1. At this time, the excitation device l
The X coordinate where O is located is X = (mXF + ΔF)・G
= (I x 1000+350)・G = 135
It is 0.G. Here, G is a constant and is used to convert the number of pulses into a desired unit distance. In Table 1,
When 0≦, F, <500, the value of data ΔF is 0 to 10.
0.200 to 300... However, if there is a possibility that there is an error in the data within the range of ±100 pulses due to noise etc., this data is expanded as shown in Table 2.

Table 2 Note that it goes without saying that the pitch number m in the data processing device 28 can be determined by numerical calculation or by drawing it out from a data table.

What has been explained above is the method of detecting the X coordinate.

If this continues, the above-mentioned periodic error cannot be eliminated. This periodic error occurs with a period of p/4 relative to the pitch p, and the magnitude of the error is approximately ±1% of p (±0.25 mm when p=25nn). 6th
Figure (A) is a diagram showing the phase difference between the phase output I obtained from the conductors 1 and 2 and the phase output H obtained from the conductors 101 and 102. 101.
This is due to the difference p/8 in the arrangement position of 102. As mentioned above, the phase error of the output signal of the adder 26 when using the 'signal induced in the conductor 1.2 will increase with a period of p/4. This becomes like the characteristic line ■ in FIG. 6(B). Furthermore, the phase error of the output signal from the adder 26 when using the signals induced in the conductive wires 101 and 102 also decays at a period of p/4. However, this is shown in Figure 6 (B)
As shown in the characteristic line (■), the p/8 shift polarity is opposite to that of the characteristic line (■).

Therefore, in this embodiment, the periodic errors are eliminated by the following calculation from the signal values when conductor pairs 1 and 2 are selected and the signal values when conductor pairs 101 and 102 are selected, and the accurate coordinate position is determined. seek. Now conductor pair l.

2 is selected, the data processing device 28 from the comparator 20
The signal input to is PDI, and its true value is PDlo.

PDlol is the signal input from the comparator 20 to the data processing device 28 when the conductor pair 101 and 102 is selected, and its true value is PDIOIO1.The difference between the two true values is PD (p/8).
Assuming that each error is 10 dl and -d2, P D 1 = P D 1 o + cl IP D
IO1=PDIOl, -d 2PD1o=PD1
01o+PD (p/8) Therefore, PD1o= (PD1+PD101+PD(p/8)
(di d2))×172 Since d1 presses d2, PDl, = (PD1+PD101+PD(P/8))
Calculate as Xi/2. Here, the difference PD (p/
8), and if the coordinate position is determined from the signal value calculated based on the above equation, the value of the coordinate position will be a value excluding the above-mentioned periodic error. Note that the above calculation was performed based on the input signal values to the data processing device 28, but the coordinate positions Xi and Xl0I are obtained as described above according to each input value,
The obtained coordinate position X1゜X101 and its true value Xlo
,

In the embodiment, a coordinate detection device using a second X and Y axis base has been described, but it goes without saying that the present invention can also be applied to a coordinate detection device using a coordinate area detection base equipped with selector conductors. Nor.

[Effects of the Invention] According to the present invention, the coordinate detection error can be reduced to 1/2 to 1/2 compared to the conventional method.
/3, making it possible to provide a highly accurate coordinate detection device at low cost.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an X-axis base used in a coordinate detection device according to an embodiment of the present invention, FIG. 2 is an electric circuit diagram of the coordinate detection device according to an embodiment of the present invention, and FIG. A specific configuration diagram of the electric circuit diagram shown in FIG. 2. 4 and 5 are characteristic diagrams showing changes in phase difference, FIGS. 6(A) and 6(B) are explanatory diagrams of the phase output and phase error reduction principle according to an embodiment of the present invention, and FIG. 7 (A). (B) is a plan view of the conventional XIII & base and second X-axis base, and Figures 8 (A) and (B) illustrate changes in the signal output from the conductor shown in Figures 7 (A) and (B). FIG. 1... First conducting wire, 2... Second conducting wire, 3.4...
・Conducting wire, 10... Excitation device, 17... Clock oscillator, 18... Counter, 20... Comparator, 21...
・Tablet, 22...Switching circuit, 23.24...
Amplifier, 25...integrator, 26...adder. 28... Data processing device, 101... Third conducting wire,
102...Fourth conductor. Patent applicant Hitachi Seiko Co., Ltd. Agent Patent attorney Masami Akimoto (1 other person) No. 11i
A 2gJ 3rd figure 'li4 m 5th figure 611 7th figure

Claims (1)

[Claims] 1. An oscillation circuit, an excitation device excited by this oscillation circuit, and a meandering first and second conductive wire in which parallel conductor portions are arranged with an electrical angle of 2π as one pitch, and are shifted by 1/4 pitch. A tablet having a coordinate axis base arranged thereon, and a phase corresponding to the coordinate position of the excitation device based on signals induced in the first conducting wire and the second conducting wire when the excitation device is placed on the tablet and excited. In a coordinate detection device comprising means for generating a modulation signal and a data processing device for calculating the coordinate position of the excitation device from the phase modulation signal, a third conductive wire having the same size and shape as the first and second conductive wires; A fourth conducting wire is arranged on the tablet with a 1/8 pitch shift from the first and second conducting wires, and the data processing device
The truth of the phase modulation signal value is determined from the phase modulation signal value obtained when the first and second pair of conductors are selected and the phase modulation signal value obtained when the third and fourth pair of conductors are selected. A coordinate detection device characterized in that the coordinate position of an excitation device is determined based on the true value.