JPS63136122A - coordinate reading device - Google Patents

Abstract

PURPOSE:To reduce a coordinate reading error produced by the tilt of a coordinate indicator by providing four fine position sense lines consisting of the electrical conductor lines having loop-shaped parts with the intervals of pitch P and connected together so that the flowing current directions are set opposite to each other at the loop-shaped parts adjacent to each other, while shifting them by every width Z in the direction of detecting coordinate axis. CONSTITUTION:A fine position sense line group 51 contains four fine position sense lines S1-S4 consisting of electrical conductor lines forming the loop-shaped parts with the intervals of pitch P and connected to each other so that the flowing current directions are set opposite to each other at the loop-shaped parts adjacent to each other. These four sense lines are set on a flat plate 5 with parallel shifts given toward an X axis every Z with the prescribed shift width Z=P/4=l(loop width). The induced voltage of each of lines S1-S4 is detected by an induced voltage detecting circuit via a switch circuit based on the alternating induced voltage produced between a terminal TSc and each of terminals TS1-TS4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electromagnetic induction type coordinate reading device, and more particularly to a coordinate reading device that reduces coordinate reading errors caused by the inclination of a coordinate indicator having an excitation winding.

[Conventional technology]

In the conventional device, as described in Japanese Patent Publication No. 55-34855, two senses 11fs+io arranged in a rectangular wave shape with a period of pitch P are laid on a flat plate with an offset of P/4 from each other. Due to the phase relationship between the composite voltage signal of the alternating induced voltages induced in the main sense line and the excitation alternating voltage signal that excites the excitation winding built into the coordinate indicator, a so-called rectangular waveform (repetitive Obtain the position information P0 of the coordinate indicator within the cycle, and determine in which cycle the coordinate indicator is located by determining the magnitude of the alternating induced voltage induced in the loop-shaped coarse position sense line laid in each repeated cycle. Inspected.

It is detected by the installation position of the coarse position sense line that gives the maximum value.

However, sense line 1. , 20, the magnitude of the alternating induced voltage induced in
I z, varies depending on the position in the detection coordinate axis direction with respect to 910, and also varies depending on the position in the vertical direction with respect to the flat plate on which the sense ljsμ0 is laid and the inclination of the coordinate indicator.

With respect to the vertical position, the relative magnitude of the alternating induced voltage induced at 2° with respect to the sense line Lll does not change, so no coordinate reading error occurs, but if the coordinate indicator is tilted, that is, If the excitation coil is tilted with respect to the flat plate, the sense wire 1. The relative magnitude of the alternating induced voltage induced in the LO changes, resulting in a difference between the coordinate reading position and the actual indicated position.

In particular, in the case of a pen-shaped seated position indicator, general operators often use the coordinate indicator at an angle, and conversely, forcing the operator to use it with restrictions on inclination places a heavy burden on the operator. Not only that, but it also makes it impossible to input small characters and shapes.

[Problems to be Solved by the Invention] The prior art described above does not take into account the inclination of the coordinate indicator, and there is a problem in that the inclination of the coordinate indicator causes coordinate reading errors.

An object of the present invention is to provide a coordinate reading device that reduces coordinate reading errors caused by the tilt of a coordinate indicator.

[Means for solving problems]

The above purpose is to connect a micro-position sense wire made of an electric conductor wire having loop-shaped portions at intervals of pitch P and connected so that the directions of current flowing in adjacent loop-shaped portions are opposite to each other on a flat plate. 4 by shifting it by a predetermined width Z in the direction of the detection coordinate axis.
Induced voltage detection that sequentially scans and detects the induced voltage at a predetermined phase timing of the excitation alternating voltage signal that excites the excitation winding of the fine position sense wire group that is actually installed, and the alternating induced voltage signal induced in the fine position sense wire. a polarity determination circuit for detecting whether the phase of the alternating induced voltage signal is in phase with the phase of the excitation alternating voltage signal; A maximum value fine position sense line detection circuit that detects a position sense line, a sense line number of a fine position sense line S obtained from the maximum value fine position sense line detection circuit, and a polarity determination circuit of a polarity determination circuit for this sense line. Based on the result P(SrL), each fine position sense II Si (L
−1 to 4) of the polarity normalized induced voltage of each fine position sense line obtained from the induced voltage polarity normalization circuit; The polarity normalized induced voltage of the fine position sense line sn-+ located on the left side of the fine position sense line SrL++ located on the left side of the fine position sense line SrL++ located on the right side of the fine position sense line NjASn where the magnitude of the induced voltage is maximum, An induced voltage correction circuit that corrects the induced voltage according to the magnitude and polarity (positive/negative) of the polarity normalized induced voltage, the magnitude of the induced voltage of the fine position sense line where the magnitude of the induced voltage is maximum, and the induced voltage This is achieved by determining the position of the coordinate indicator based on the correction voltage obtained from the correction circuit.

[Effect]

The fine position sense lines are connected in such a way that the directions of current flowing in the five adjacent loops are opposite to each other, so the magnitude of the alternating induced voltage induced in the fine position sense lines is determined by the coordinate indicator. The position of is maximum at the center position within the loop of the loop-shaped part, and becomes smaller as you move away from the center position.

When it approaches the next loop-shaped part, it becomes larger again.

It is maximum at the central operculum within the loop.

At this time, the phase relationship between the alternating induced voltage and the excitation alternating voltage supplied to the excitation winding is reversed from in-phase to anti-phase or from anti-phase to in-phase. (Either in phase or out of phase.

) In other words, the induced voltage characteristic, which takes into consideration the magnitude and polarity of the alternating induced voltage signal induced in the fine position sense line with respect to the movement of the coordinate indicator, is a repeating cycle with a period of 2P for the arrangement pitch P of the loop-shaped part. .

Here, the loop width of the loop-shaped part of the fine position sense line is 1
A group of four fine position sense lines consisting of ρ is laid out on a flat plate, with Ztf: P/4 and Ztf: P/4, the reference point of the detection coordinate axis is determined in advance, and the coordinate reading range is divided into periods of 2P ( Each divided region is called a periodic region), then the induced voltage detection circuit detects the predetermined phase timing of the excitation alternating voltage signal that excites the excitation winding of the alternating induced voltage signal induced in each fine position sense line. Since the induced voltage is detected at the timing at which it takes a positive peak value, the detected induced voltage will take a positive or negative value.

This positive/negative sign indicates whether the phase of the alternating induced voltage signal is in phase or opposite to the phase of the excitation alternating voltage signal among the loop-shaped portions of the fine position sense line. Information on where is located.

Therefore, the polarity determination circuit determines whether the phase of the alternating induced voltage signal is in phase with the phase of the excitation alternating voltage signal, depending on whether the induced voltage is positive or not.

The maximum value fine position sense line detection circuit detects the fine position sense line with the maximum magnitude of the induced voltage among the fine position sense lines, so it can determine the polarity of the detected fine position sense line and the sense line. Depending on the circuit polarity judgment result, the period 2P
It is possible to detect in which of the small areas divided into 2xa equal parts the coordinate indicator is located. Furthermore, which periodic region of the periodic region 2P is located can be detected by a method using a rough position sense line similar to that described in Japanese Patent Publication No. 53-54855 (the above-mentioned conventional device). can.

Furthermore, the detailed position of the coordinate indicator in the previous small area is determined by the induced voltage value of the fine position sense line that has the maximum induced voltage, the left steepness of the fine position sense line that gives this, and the fine position sense line adjacent to the right. It can be detected from the relative relationship between the magnitude of the induced voltage in the line or the magnitude of the induced voltage in the four fine position sense lines.

Ru.

When the coordinate indicator moves in a small area parallel to the coordinate detection axis in a direction perpendicular to the flat plate (MCM), the characteristics of the induced voltage of the four fine position sense lines are as follows.

The fine position sense line with the maximum induced voltage in this small area is SrL, the fine position sense line located on the left side of this sense line is 5n-11, and the fine position sense line located on the right side is Sn+1. ．． The remaining one fine position sense line is connected to Sr.
If L+z, the magnitudes of the induced voltages of Syb and Sn+2 are symmetrical about the center of the small region, and S at the center of the small region.

is the maximum, and Sn+2 is the minimum induced voltage characteristic. In addition, S, -1 and SrL+1 have complementary characteristics in which as one becomes larger, the other becomes smaller,
The sizes of both become equal at the center of the small area.

Moreover, within a small region, the large magnitude of the induced voltage of Sn is
The magnitude of the induced voltage of the thickest (, s1+2) of the four fine position sense lines is the smallest.

Within this small area, only -Srb+z is in the center of the small area, and the polarity determination result is inverted.However, this does not apply if the coordinate indicator is tilted.

As the slope increases, the complementary relationship between the magnitudes of the induced voltages between 5n-1 and Sn++ breaks down, and one becomes larger and the other becomes smaller. Which one becomes larger depends on the direction of the slope. Furthermore, the polarity reversal position of S, +2 deviates from the center position of the small area, and the magnitude of the induced voltage becomes larger in the small area part in the opposite direction of the deviation.
The magnitude of the induced voltage between SrL+1 and SrL+1 becomes larger than the magnitude of the induced voltage of the reduced fine position sense line.

Therefore, if the polarity of the induced voltage of SrL+2 is always reversed from positive to negative in each small region, then when the coordinate indicator is tilted, by looking at the normalized polarity value of S3+2, , the direction of the slope can be known, and the degree of the slope can be determined by the magnitude of the induced voltage of S +2.

For this purpose, the induced voltage polarity normalization circuit uses the sense line number of the fine position sense msF& obtained from the maximum value fine position sense line detection circuit and the polarity judgment result P(Si) of the sense line polarity judgment circuit. The polarity of the induced voltage of each fine position sense line is normalized according to a preset rule.

The induced voltage correction circuit is S! The direction of the tilt of the coordinate indicator is detected based on whether the polarity normalized induced voltage of %+2 is positive or negative,
The magnitude of the induced voltage, mix &-1 and S +
A correction amount is calculated based on the relative magnitude of the induced voltage of No. 1, and this is calculated as Sn-+ and Sn+.

The induced voltage is added to one side and subtracted from the other side.

As a result, the 83
-1. It is possible to correct the induced voltage of the S unit and use the corrected induced voltage to calculate the detailed position of the coordinate indicator within a small area, reducing coordinate reading errors caused by the tilt of the coordinate indicator. becomes possible.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a block configuration of an embodiment of the present invention, in which 1 is an excitation winding drive circuit, which is composed of an alternating voltage generation circuit 2 and an amplifier 5, and is internally connected to a coordinate indicator 4. excitation winding (
05, 6, 7 and 8 connected to (not shown) are flat plates made of insulating material and stacked on each other. The flat plate 5 is permanently provided with a group of fine position sense lines 51 for X fine rain shown in FIG. 3, and the flat plate 6 is permanently provided with a group of coarse position sense lines 61 for X fine rain shown in FIG. On the flat plate 7,
The Y-axis peripheral fine position sense line number 1, which is obtained by rotating the laying pattern similar to the X fine rain fine position sense line group 51 by 90 degrees, is placed on the flat plate 8 in the same way as the X fine rain coarse position sense line group 61. A Y-axis circumferential coarse position sense line group 81 is laid out by rotating a 90-degree number pattern.

Each sense line group 51 , 61 , 71 and 81 is connected to ten induced voltage detection circuits via a switching circuit 9 .

The induced voltage detection circuit 10 includes an amplifier 11. filter 15,
Sample hold circuit 13. Consisting of an A/D converter 14 and a peak timing detection circuit 16, its output 101
is connected to the polarity determination circuit 17 and the coordinate detection circuit 18.

The coordinate detection circuit 18 includes a fine position detection circuit 19. It is composed of a coarse position detection circuit 20 and an adder 21, and this adder 21
The output becomes the output 181 of the coordinate detection circuit 1st.

23 is a control circuit, is it a switching circuit? , induced voltage detection circuit 1
0 and a control signal 2 that controls the operation of the coordinate detection circuit 18.
31, 232, 233 and 234 are connected to each circuit.

Further, the fine position detection circuit 19 includes a sense line data storage circuit 191. Induced voltage polarity normalization circuit 198. Induced voltage correction circuit 199, dual signal conversion circuit 19
2. It is composed of a normalization circuit 1932, a position conversion circuit 194°, a maximum value fine position sense line detection circuit 1952, an intra-period offset value calculation circuit 196, and an adder 197.

The coarse position detection circuit 20 includes a maximum value coarse position sense detection circuit 2012, a cycle number determination circuit 202, and a cycle reference point position calculation circuit 203.

Outline of operation of the present embodiment In the coordinate indicator 4, an excitation winding is excited by an excitation alternating voltage signal from the AT magnetic winding drive circuit 1, and an alternating magnetic field is generated around the excitation winding.

When this coordinate indicator 4 is brought close to the flat plates 5 to 8, sense line groups 51 and 61 are laid on the flat plates 5 to 8 by an alternating magnetic field.
, 71 and 81, an alternating induced voltage is induced in each sense line.

The switching circuit 9 is controlled by a switching circuit control signal 231, and in order to select one sense line from the sense lines of each sense line group 51, 1, 71 and 81, a switch connected to each sense line (see FIG. (not shown), only the corresponding switch is closed, and the alternating induced voltage of the selected sense line is guided to the induced voltage detection circuit 10.

The control circuit 23 controls the switching circuit 9 to selectively scan each sense line in a time-division manner.

The induced voltage detection circuit 10 detects an induced voltage at a predetermined phase timing (positive peak timing) of an excitation alternating voltage signal of an alternating induced voltage signal induced in a selected sense line.

The polarity determination circuit 17 determines whether the phase of the alternating induced voltage signal of the selected sense line is in phase with the phase of the excitation alternating voltage signal, depending on whether the induced voltage obtained from the aforementioned induced voltage detection circuit 10 is positive or negative. Determine based on K.

The coordinate detection circuit 18 determines the position of the coordinate indicator 4 based on the induced voltage of each sense line and the determination result of the polarity determination circuit 17.

To be more specific, the fine position detection circuit 19 constituting the coordinate detection circuit 18 detects the induced voltage due to the inclination of the coordinate indicator 4 based on the induced voltage and polarity determination result of each sense line of the fine position sense line group 51. The coarse position detection circuit 20 corrects the voltage fluctuation and detects the fine position based on the relative magnitude of the corrected induced voltage of each fine position sense line.
The coarse position is detected based on the induced voltage of each sense line of 1 and the fine position obtained from the fine position detection circuit 19, and the position of the coordinate indicator 4 in the X-axis direction is determined by adding both values by the adder 21. decide.

Similarly, fine position sense line group 71. Rough position sense line details 81
The position of the coordinate indicator 4 in the Y-axis direction is determined based on the induced voltage and the polarity determination result.

Since the method of determining the position of the coordinate indicator 4 in the X-axis direction and the Y-axis direction is the same, the following explanation will only describe the method of determining the position in the X-axis direction and the operation.

The details (configuration and operation) of each component will be described below.

Laying pattern of fine position sense line group FIG. 3 shows a laying pattern of fine position sense line group 51 according to an embodiment of the present invention.

The fine position sense wire group 51 includes fine position sense wires Si that have loop shaped portions at intervals of a pitch P, and are made of electric conductor wires connected so that the directions of current flowing in adjacent loop shaped portions are opposite to each other. ．． It consists of four wires: 82, Ss and S4.

These four fine position sense lines are laid on the flat plate 5 by shifting them by a predetermined width Z, here Z-P/4-2 (loop width), parallel to the X-axis.

One end of each fine position sensor 1ilst to S4 is connected to a terminal TSi.
~ T S a to the switching circuit 9 .

In addition, the other ends of each fine position sense i S+ -S4 are connected to each other at point H shown in the figure, and from that connection point there is an adjacent inter-loop coupling portion that connects adjacent loop shaped portions of each fine position sense line. It is led to terminals TS arranged near terminals TS+ to TS4 via a control wire Sc made of an electric conductor wire laid parallel to the terminals TS+ to TS4.

The induced voltage of each fine position sense line 81 to S4 is the terminal TS,
The induced voltage detection circuit 10 detects the induced voltage via the switching circuit 9 based on the alternating induced voltage generated between the terminals TSi to TS4.

Induction characteristics of fine position sense line FIG. 5 is a diagram illustrating the induction characteristics of one fine position sense line Si.

FIG. 5 is an enlarged view of a part of the laid butter 7 of the fine position sense line group shown in FIG.

FIG. 5(2) shows the laying pattern of the fine position sense line Si shown in (1). Position areas B, D, and F shown in the figure are loop-shaped portions, and position areas A, C, E, and G are connecting portions between adjacent loops. Point H is the connection point between the fine position sense line Si and the return line So.

Also, the arrows in FIG. 5 (2) and (3) indicate the terminal TS+
It shows the direction of the current in the electrical conductor wire portion of each part when the current flows from the terminal TSO through the connection point H to the terminal TSO of the return line SC.

As can be seen from the figure, the direction of the current is clockwise in the loop-shaped part of the position area B, counter-clockwise in the loop-shaped part of the adjacent position area D, and clockwise in the loop-shaped part of the adjacent position area F. becomes.

In this way, when one adjacent loop-shaped portion is connected with the adjacent inter-loop coupling line as shown in FIG. 5(1) or (2), the directions of currents flowing in the adjacent loop-shaped portions become opposite to each other.

Here, the relationship and interaction between the return 1faso and the connecting portion between adjacent loops will be mentioned.

The electric conductor wires of the connecting portions between adjacent loops in the position areas C, E, and G are arranged close to each other and parallel to each other. Also shown in Figure 5 (2) K.

In other words, the directions in which the currents flow in the connecting portion between adjacent loops and in the return l1lSo are opposite to each other. When the coordinate indicator 4 is positioned at the 81st point in Figure 5 (2) at 7 points, E
The electromotive force induced in the coupling part between adjacent loops in the position area of E or the induced current associated with this is e (18-11j), and the electromotive force induced in the return line Sq of the position area of E or the induced current associated with this is If the current is e (5OII!), then both electric conductor wires have the same length and are placed close to each other in parallel, so (S) -6 (Sol
) ・・・・・・・・・・・・・・・ (1).

Looking at this between terminals TS+ and TS, as shown by the arrow in Figure 5 (2), the current flows from TS+ to TSz are in opposite directions, so the current flow is generated between both terminals. The electromotive force generated or the induced current caused by this are mutually
It will be cancelled. Therefore, the instantaneous joint loop coupling portions in the position areas A, C, E, and G and the portion of the return line SO placed close to and parallel to these do not contribute to the induction characteristics, and as shown in Fig. 5 (3). Only the solid line portion shown is the coordinate indicator 4.
The alternating magnetic field created by the built-in excitation winding contributes to the generation of an alternating induced voltage. as a result,
The fine position sense is shown in FIG. 5(2) is as shown in FIG.
The electric conductor wire only in the solid line part shown in 3) contributes to the generation of alternating induced voltage, and the solid line part is 1 in the position area B.
A clockwise loop of the turn is formed, and in the position area D, a clockwise loop of one turn is formed, and in the position area F, a clockwise loop of one turn is formed.

This means that the one-turn loop line shown in Figure 5 (4) is
Loop line s,, t SD r in the position area of ,D,F
The SIF is arranged, and the alternating induced voltage eB of each loop wire is
It is equivalent to the sum of eD and eIF. (eD
(Please note that the reference voltage of θB and θF is different from that of θB and θF.) Figure 5 (5) shows this situation, where the horizontal axis indicates the position of the coordinate indicator 4, and the vertical axis indicates the alternating voltage. The phase relationship between the magnitude of the induced voltage and the excitation alternating voltage applied to the excitation winding is shown.

eE, aD, and eF in Fig. 5 (5) are loop HA
The magnitude of the alternating induced voltage of SE+SD+SIF is shown, and the thick solid line is the sum of these. Loop IS
At the center of the loop of B and SF, eE, e'J! is the maximum value, and decreases as you move away from the center (
, eD has a maximum value at the center of the loop of the loop line SD, but the phase of the alternating induced voltage is opposite to the phase of the center of the loop of the loop line 5Btsy. The induction characteristics of each loop line are the same, but the only difference is the placement position of the loop, so the result of adding these is B as shown by the thick solid line.
The induced voltage reaches a maximum in the same phase at the center of the position area of , becomes zero at point C0 (the center point between the loop-shaped parts), the phase is reversed and reaches a maximum in opposite phase at the center of the position area of D, and the induced voltage reaches a maximum at the center of the position area of D. The induced voltage becomes zero again, the phase is reversed again, and it becomes maximum in the same phase at the center of the position area of F.

In this way, the induced voltage characteristic of the fine position sense line Si has a period of 2P, which is twice the arrangement pitch P of the loop-shaped portion (it becomes a repeating characteristic).

Induction characteristics of the fine position sense line group Each of the fine position sense lines 81 to S4 is shown in FIGS. 6 and 5 (
As shown in 1), the shift width in the X-axis direction is 2-P/4-
The induced voltage characteristics of each sense line are as shown in Figure 6 (2
)become that way. FIG. 6 (5) shows each fine position sense line 8.
Figure 6 (4) shows the induced voltage V (the magnitude of the alternating induced voltage), and there is no phase information.
indicates the maximum value of the induced voltage v (i) of each fine position sense line S, ~S4 at each position, and the fine position sense lines that give that value are sequentially applied from point R1 as shown in the figure. 81+ S2 rSs, S4 T S-+,
S2)... In addition, the phase of the alternating induced voltage of the fine position sense line that gives the maximum value has a period of 2P (2 widths are in phase) with respect to the phase of the excitation alternating voltage that drives the excitation winding, as shown in Figure 6 (5). 2-width anti-phase) (this is repeated. In this way, the induction characteristics of the fine position sense line group are repeated with a period of 2P.

Switching circuit operation timing FIG. 7 shows the operation timing of the switching circuit 9, and (1) shows the switching circuit control signal 231 which is supplied from the control circuit 23 and indicates the code of the sense @Si to be selected.
, (2) is the switching circuit 9 connected to the sense 1Jsi
Opening/closing timing of internal switch sw, and (3)
is the output signal of the switching circuit 9 and the selected sense @S
denotes the alternating induced voltage of i (Si).

5, the switching circuit 9 is controlled by the switching circuit control signal 261 to select each sense line in time series.

The control induces an alternating induced voltage on the selected sense line.

It leads to the voltage detection circuit 10.

Induced voltage detection circuit The induced voltage detection circuit 10 generates an alternating induced voltage signal induced with the sense line number selected by the switching circuit 9; an induced voltage signal at a predetermined phase timing (positive peak timing) of the excitation alternating voltage signal (t). Voltage.

In order to detect the IP, first use the ; (number) as an amplifier.

11 amplifies the signal, and filter 12 removes unnecessary noise components.

After the signal is removed, the signal is input to the sample/hold circuit 13.

The sample and hold circuit detects peak timing.

- The sample/hold operation is controlled by the output signal of the output circuit 16, and the instantaneous value of the alternating induced voltage signal N(R) at the positive peak timing of the excitation alternating voltage signal is held.

FIG. 8 shows the internal configuration of the peak timing detection circuit 16. The peak timing detection circuit 16 includes a low pass filter 161. Comparator 162 and D-type flip 70 tube 1
It consists of 63. The corner frequency f0 of the low-pass filter 161 is the alternating frequency 10 of the alternating voltage generating circuit 2.
Since it is set sufficiently small, low-pass filter 1
61, a signal whose phase is shifted by 90° with respect to the rjjha alternating voltage signal (FIG. 9 (1)) of the alternating voltage generating circuit is obtained.

The comparator 162 (shown in FIG. 9(2)) compares this 90° shifted signal with a predetermined value (zero) to
As shown in Figure 9 (3), a rectangular wave that rises at the timing of the positive peak value of the excitation alternating voltage signal is output, and this is
It is supplied to the C100k terminal of type flip-flop 165. The Data input terminal of the D-type flip-flop 163 receives a sample-and-hold control signal 2!12 (FIG. 9 (4)
) is input to the output terminal Q of the D-type clip-flop 163, and the sample-and-hold control signal 232 is a rectangular wave (cloak terminal input signal) that rises at the timing of the positive peak value of the excitation alternating voltage signal. The sampled value is output at the rising timing. In other words,
As shown in Figure 9 (5), the sample is held at the timing of the positive peak value of the excitation alternating voltage signal.
Controls the hold circuit 15.

Here, as shown in FIG. 9 (6), the 1 switching circuit control signal 231 switches at timing T2 to select the sense 171 Sn and SrL+1, and on the other hand, as shown in FIG. 9 (7), The alternating induced voltage signal ":;<sn),;<snear,)" is input to the input terminal of the sample-and-hold circuit 13, and (S+s) is in phase with the excitation alternating voltage signal, Assuming that is an alternating induced voltage signal having a phase opposite to the excitation alternating voltage signal, the sample-and-hold circuit 15 is configured to control the timing of T+, that is, as described above.
At the positive peak value timing of the excitation alternating voltage signal; (S,
, ) hold the value. Since (Sy&) was in phase with the excitation alternating voltage signal, the positive peak value of (SFL) is held.

Furthermore, the negative peak value of ';' (SFL+1) is It will be held. This situation is shown in FIG. 9 (8).

These values held by the sample and hold circuit 13 are converted into digital values by the A/D converter 14 as shown in FIG. 9 (9). At this time,";;
(Sn) + ';; A/D for (SyL++)
The output of the converter 14 is converted into V (Si1), V (Sn
++), V(S,) is a positive value, V(SrL
++) takes a negative value, and its size is 7(
This indicates the magnitude of the amplitude of Sn>,;;-<Sn+1).

By the above-described operation of the induced voltage detection circuit 10, as shown in FIG.
)K (in the figure, the induced voltage (having polarity) V(SL) of each fine position 7" base wire Si (indicated by (in the figure)) can be obtained.

Therefore, the polarity determination circuit 17 is composed of a comparator 170 as shown in FIG. 8, and the induced voltage detection circuit 10
Depending on whether the output (output of the A/D converter 14) is larger than the threshold value (zero in this case), that is, whether it is a positive value or a negative value, the alternating induced voltage -(Sn) Determine whether it is in phase with the voltage signal.

This comparator 170 is a comparator that compares digital values, but it is configured with a comparator that compares analog values, with one input being the output of the sample and hold circuit 13, and the other input being zero. A similar effect can be obtained by outputting the comparison result at the hold timing of 13.

Let the polarity determination result of the sense line Si be p(SL), and P(S
When ri is in phase, 1. It assumes a value of -1 when the phase is reversed.

Moreover, if the switching timing of each sense line of the switching circuit 9 is the timing of T2, that is, the zero cross timing of the excitation alternating voltage signal, as shown in FIG.
), the alternating induced voltage between the sense lines Sn and SW+
;; (SFL) , ";;(SF&++) values are
At the timing of T2, both become zero, so the transient response time (depending on the response characteristics of the amplifier 11 and filter 12) at the time of switching becomes small, and the induced voltage of each sense line using a high-speed A/D converter is reduced. Scanning detection and, in turn, the speed of coordinate reading can be increased.

The coordinate detection circuit 18 detects the induced voltage V (S
+) ~ v(s4) and the polarity determination result p of the polarity determination circuit 17
(s+) to P (S4), correct the fluctuation of the induced voltage due to the inclination of the coordinate indicator 4, and from the relative magnitude K of the induced voltage of each corrected fine position sense line, fine position sense A fine position detection circuit 19 detects a position (referred to as a fine position) within a period of 2P, which is twice the arrangement pitch P of the loop-shaped portion of the machine, and a coarse position sense line group 61 (shown in FIG. 4). Based on the induced voltage (details will be described later) and the output result of the fine position detection circuit 19, it is determined in which periodic region divided by the width of 2P the coordinate indicator 4 is located. A coarse position detection circuit 20 detects and outputs the position of a reference point in the periodic region (referred to as a coarse position), and an adder 21 adds the fine position and coarse position and outputs the read position of the coordinate indicator 4. Consists of.

The operations of the fine position detection circuit 19, the coarse position sensor 2-line detail 61, and the coarse position detection circuit 20 will be described below.

Fine position detection circuit The fine position detection circuit 19 detects the induced voltage V (S
+) to V(S4) and the polarity determination result P of the polarity determination circuit 17
(Ss) to P(84) are taken in and stored in the sense line data storage circuit 191. Specifically, the induced voltage V
(S+) ~V (S4) Rami pressure K Memo! 719
11, the polarity determination results P(S+) to P(S4) are stored in the polarity value memory 1912 in predetermined areas corresponding to the sense line numberers -1 to -4 of the fine position sense line SL.

Here, as shown in Figure 6 (6), the coordinate reading range is set to 2.
The reference point of the first periodic region ksi, which is divided into regions with a width of P and counted from the reference point of the coordinate axes, is the Ri point, and the Ri point is the maximum induced voltage of 5 as shown in Figure 6 (5). It is assumed that the point where the result of the dumbness determination of the fine position sense line that gives Further, the periodic area person Si having a width of 2v with the RL point as the reference point is abbreviated as period number &.

The fine position detection circuit 19 cannot detect in which periodic region the coordinate indicator 4 is located based on the values stored in the sense line data storage circuit 191 (this detection is performed by the coarse position detection circuit). The position of the periodic region set as described above from the reference point (this is called the periodic self-position) is detected by K as follows.

First, the maximum value fine position sense line detection circuit 195 detects the maximum induced voltage among the induced voltages V(S+) to V(84), and provides the fine position sense line 1asn.
The sense line number rL (hereinafter referred to as the maximum fine position sense line number) and the polarity determination result P(src) are output. is a value of 1 to 4.

Here, if the coordinate indicator 4 is positioned at the point A shown in FIG. 3(1), the induced voltage V(Ss ) becomes the maximum, and the polarity determination result P (Ss) of V (Ss) is
Since they are in phase (positive), the maximum amm position sensing paddy type detection circuit 95 outputs n-5, P (Sg) - in phase. It can be seen that the device 4 is located in the small region 3 of the small regions (A+ to As) obtained by dividing the periodic region into 8 as shown in FIG. 6(6).

The intra-period offset value calculation circuit 196 calculates the maximum fine position sense line number path obtained from the maximum value position sense line detection circuit 195 and the polarity determination result P (S,) of the alternating induced voltage of the sense line. Based on this, the coordinate indicator 4 detects in which small region it is located, and calculates the offset value of the detected small region from the reference point of the periodic region.

The width of the small area is the width of the fine position sense type [Z, so the offset value is X. 'FT is calculated by the maximum fine position sense line number with a value of 1 to 4, and P (SrL) is the polarity determination result of the alternating induced voltage of the fine position sense line S with respect to the excitation alternating voltage.

The detailed position of the coordinate indicator within the detected small area is determined by the induced voltage polarity normalization circuit 198. Induced voltage correction circuit 199.2
The signal conversion circuit 195, normalization circuit 195, and position conversion circuit 194 detect as follows.

In particular, the operation of the induced voltage polarity normalization circuit 198 and the induced voltage correction circuit 199 is a feature of the present invention, which corrects fluctuations in the induced voltage due to the tilt of the coordinate indicator 4.

First, the induced voltage polarity normalization circuit 198 selects each fine position sense line S stored in the sense line data storage circuit 191.
Induced voltage V (Si) of i (i-1 to 4).

Each fine position sense is The polarity of the induced voltage on line SL is normalized to the polarity normalized induced voltage VT.

Outputs vL, vR, and VB.

V, r-1v (S,)I ・(3)V
L-CPL(')"P(Ss)・v(Syi-+)
-(4) VH=CPR(n) ・P(SrL) ・V(
Sn++) ”(5nv,, -CPB(le)・P(
Sle)・V(Sn+2)...(6) However, CPL(Fl&), CPR(i), CPB(7L)
is a polarity normalization coefficient that takes a preset value of 1 or -1 corresponding to 9, and when roof < 1, ru i - (ru j) + 4 ru + i>
When 4, Le+7-(n+1)-4 Also, P(SrL
) is in phase when 1. It assumes a value of -1 when the phase is reversed.

The polarity normalized induced voltage vT is the induced voltage V (Ss) of the fine position sense line Sn which gives the maximum fine position sense line number.
, and vL is the induced voltage V(S
n−+), and vR is the induced voltage V of the fine position sense line S+1 located on the right side of the fine position sense line Si.
(SrL++) and vB corresponds to the induced voltage v (SrL+2) of the remaining fine position sense line SrL+2.

Here, if the polarity normalization coefficients CPL (l), CPR (→ and CP B (fi)) are set as shown in Table 1 in accordance with l, the polarity normalized induced voltage v=lv, , t The polarity (positive/negative) of VR and vB is determined by the maximum fine position sense line number and the polarity determination result P of that sense line (83) Which of the small areas where the coordinate indicator 4 detected by the IC is located? can be made equal even in a small area of .

The values of the polarity normalization coefficients in Table 1 are the polarity normalized induced voltage VT
The polarity relationship of F VL , VB and vB is set in each small area to be equal to the polarity relationship of the induced voltage of each fine position sense line in the small area As shown in FIG. 6 (2). .

In Figure 10 (1), the fine position sensor, x, line Sn,
Sn-, rSn+1. The arrangement relationship of the loose-shaped portion of SrL+4 is shown in FIG. 10 (2), and the polarity normalized induced voltage VT, VLJVR+VB (solid line part) in the small area (area from point B0 to point B2 in the figure) is shown. show.

Coordinate indicator within the small area detected by this.

The detailed position of No. 4 (hereinafter referred to as small area position ΔX) is:
The polarity normalized induced voltages VT*v,,l can be detected by the relative magnitudes of VR and vB.

Changes in induced voltage characteristics due to the tilt of the coordinate indicator However, the induced voltage characteristics shown so far (Figures 6 and 10) are
When the coordinate indicator 4 is pointed perpendicular to the flat plate (no tilt), and when the coordinate indicator 4 is tilted to the flat plate, the induced voltage characteristics of each fine position sense line are as shown in Fig. 6. , will be different from FIG. 10.

This is because, as shown in Figure 3 of Japanese Patent Publication No. 58-165 CI6, when the coordinate indicator 4 is tilted, the distribution of the alternating magnetic field generated from the excitation winding is also tilted, and as shown in Figure 5 (4). This is due to the change in the vertical direction of the magnetic flux that interlinks the equivalent loop shape shown in .

FIG. 11 shows trends of the polarity normalized induced voltages vT + vL t vR and vB with respect to the inclination of the coordinate indicator 4.

In Fig. 11 (1), the inclination is 0° (no inclination'), (
2) shows the characteristics within a small region of the polarity normalized induced voltage with a slope of 10° and (3) with a slope of 45°. Further, (4) shows the characteristics when the inclination is -10°, and (5) shows the characteristics when the inclination is -45°.

In the case of a positive slope (Fig. 11 (2) t (3)), as the slope increases, VTJ becomes thicker (and vR becomes smaller, the complementary characteristics of the two shift, and the polarity reversal position of VB becomes smaller. Gradually to the right from the center of the area (in the diagram)
If the slope becomes extreme as in (3), V
B always takes a positive value, and VR causes polarity reversal within a small region. (It will take a negative value.) Conversely, in the case of a negative slope (Figure 11 (4), (5)
), as the slope increases, vL becomes smaller and vR becomes larger, and the polarity inversion position of vB gradually shifts to the left (in the figure) K from the center position of the small region (.

When the slope becomes extreme as in (5), V and B always take negative values, and vL causes a polarity reversal within a small region. (It takes a negative value.) Also, the absolute value of VB tends to increase as the slope increases.

As shown in FIG. 11, when the induced voltage of each fine position sense line, and hence the polarity normalized induced voltage, change depending on the inclination of the coordinate indicator 4, the polarity normalized induced voltage VT,
The relative sizes of VL, VB, and VB will differ, and the position ΔX within the small region will vary depending on the slope.

The induced voltage correction circuit 199 adjusts each polarity normalized induced voltage to the inclination of the coordinate indicator 4 in order to reduce the variation in the position ΔX in the small area due to the inclination of the coordinate indicator 4, that is, to reduce the occurrence of coordinate reading errors. The correction is made according to the direction and degree of inclination.

In this correction of the induced voltage, as shown in FIG. 11, the polarity-normalized induced voltages V and B increase in magnitude in proportion to the degree of inclination of the coordinate indicator 4. , takes a positive value, and in the case of a negative slope, takes a negative value.Using this property, the degree and direction of the inclination of the coordinate indicator 4 are detected, and each polarity normalized induced voltage is detected by the coordinate indicator 4. The correction is made to more closely approximate the characteristics of each polarity normalized induced voltage at a slope of 0° in No. 4.

The specific operation of this induced voltage correction circuit 199 will be explained below.

The induced voltage correction circuit 199 has vB as shown in FIG.
B-sexuality detection circuit 1991, correction amount ΔV calculation circuit 1992
and a correction voltage calculation circuit 1993.
is a positive value or a negative value, and if the detection result is positive, the coordinate indicator 4 determines that it is tilted in the positive direction, and if the detection result is negative, the coordinate indicator 4 is determined to be tilted in the negative direction, and depending on the direction of each tilt, VL t vR
and vB, the correction amount ΔV calculation circuit 1992
．． Controls the operation of the correction voltage calculation circuit 1995.

When VB is positive (cases (2) and (5) in Figure 11)
The correction deviation ΔV calculation circuit 1992 calculates the correction amount ΔV using the following equation.

This correction amount △V is proportional to the magnitude of vB and inversely proportional to V□T, so the position within the small area △X
is large near 0, and as ΔX increases, it becomes smaller due to removal, and becomes zero near Δx-Z.

The correction voltage calculation circuit 1993 corrects the polarity normalized induced voltage v, , l VR as shown in the following formula based on this correction amount ΔV, and outputs the corrected voltage nVI, , l VR.

rLVB −VR+ △V −(
9) nVL-VL-(VB-△V)
・(1o) The above formula adds the correction amount △V to vR and calculates (lY
nl - ΔV) is subtracted from vL, so when the coordinate indicator 4 is tilted in the positive direction, vR becomes smaller and VL becomes larger due to the tilt, as shown in Fig. 11 (2) and (5). It will be compensated for.

FIG. 13 shows the correction results at an inclination of 45°.

The dotted line in the figure is the polarity normalized induced voltage, and the solid line is the corrected induced voltage.

As is clear from this figure, the corrected induced voltage rL
VL r "VR is the position within the small region △x - Z / 2
The characteristics are complementary, centered around , and the characteristics are corrected to be almost the same as those without tilt.

Also, if VB is negative ((') + ('') in Figure 11
In the case of , the correction amount ΔV calculation circuit 1992 calculates the correction amount ΔV as follows, and the correction voltage calculation circuit 1993 calculates the polarity normalized induced voltage vLy VR based on this correction amount ΔV as nvL − vL
+△V ・(13)nVR−VR
-(1vnl-ΔV)-(14), and output the corrected voltages nvL and rbvH.

FIG. 14 shows the correction results at an inclination of -45°.

A correction voltage rLVL r rLvR similar to that in FIG. 15 is obtained.

Even when the coordinate indicator 4 is not tilted, the induced voltage correction circuit 199 corrects the polarity normalized induced voltage VB when ΔX is less than or equal to Z/2, as shown in (1) in FIG. takes the value of , and takes a negative value when it is greater than or equal to 2, so the polarity normalized induced voltage v, , as described above, corresponds to the positive/negative of VB.
However, since the magnitude of vB is small and is symmetrical about Δx-Z/2, the correction amount ΔV is small and Δat-Z/2. It is symmetrical about the center, and the relative magnitudes of the correction voltages VI and rbV'H are also △X-Z/2
It is symmetrical around the center. This situation is shown in FIG.

As explained above, the correction voltage calculation circuit 1993
vB polarity ratio frequency 1% 1991 judgment result, that is, v
Corresponding to whether B is a positive value, the correction amount ΔV calculation circuit 199
VLt V, based on the correction amount ΔV obtained from 2.

is corrected and outputs corrected voltages RVL and nVH.

Furthermore, this correction voltage calculation circuit 1995 calculates “VT=
As vT・(15), rLVT is output, and m
-Based on rLVL, n''JH and nvT, the VB correction voltage rLVB is calculated by the following equation and output.

However, mαX(α, b) indicates the larger value of α and b.

m1n(α, b) indicates the smaller value of α and b.

The above equation is used to obtain a correction value for the magnitude IVBl of vB caused by the inclination K of the coordinate indicator 4, and the 15th. vB according to the above equation for each slope shown in @14 and FIG. 15 is shown in each figure.

rLvB Good, as shown in the above figures, when the position in the small area is △J wa Q, it becomes equal to the value of rvR, and △X
It gradually decreases as
It becomes equal to the value of L.

Also, let vB be calculated using an experimentally determined constant, so that it becomes 0 when △x -Z/2.
You can also do it.

Detection of position within a small area Correction voltages obtained by the induced voltage correction circuit 199 described above
Based on this, the detailed position within the small area where the coordinate indicator 4 is located (position within the small area △ do.

First, the two-signal conversion circuit 192 calculates two combined voltages N'S + VO shown in the following formula.

VS −nVT−nVL+n, VRnVB −
(18)■(3-nVT+ nVL-nVH-rLVB
-(19) Here, the value of each correction voltage is
If the value shown in (1) in Figure 6 is taken, the composite voltage vs is the first
As shown in (2) of Figure 6, at △x-0, Va becomes zero, gradually increases as △X increases, and at △x-772, Va,
Further increases at △x-7, 2 (Vb - Va )
It has a monotonically increasing characteristic. Also, the composite voltage Va is △
At J wx Q 2 (Vb - V4 ), contrary to VS, it gradually becomes smaller, ΔXXkeg: (Va becomes smaller, and becomes zero at Mu X-Z, resulting in a monotonically decreasing characteristic).

The normalization circuit 195 calculates the relative magnitude of the composite voltage vs t ''O, that is, the normalized value ρ, using the following equation.

VS This normalized value ρ is, as shown in FIG. 16 (3), Δf
w 0 at Q. 1/2 at Δxwg2. A monotonically increasing characteristic becomes 1 at Δx−Z.

In other words, the normalized value ρ ranges from 0 to 1, and each value corresponds to a unique position ΔX within the small area.

Therefore, by detecting the normalized value ρ, the corresponding ΔX can be detected.

This normalized value ρ may have a monotonically increasing characteristic or a monotonically decreasing characteristic in the range of ΔX from 0 to 2, and is not limited to the above-mentioned formula for calculating ρ.

For example, the following margin may be calculated as ρ, which monotonically increases from 0 to A in the range of ΔX from 0 to Z, such that A is a constant constant.

The normalized value ρ is 0≦ρ≦ for △X where 0≦ΔX≦Z
It becomes a unique function of ΔX that takes the value of 1, and ρ−? (△X)
...(22) It is expressed as follows.

This function? If (△X) is a function, then ΔX is, from ρ, Δ C ≧ Knee 4 Fist ρ ・・
- Obtained by (24). However, as shown in No. 16 [N(3)], is the function? (△X) takes a value that has a non-linear relationship with △X.

So, what about this function? Reverse r of (△X)! 4 number 7 (ρ) Δx-7(ρ) ...If you experimentally find a function table that satisfies (25), you can obtain ΔX from the value of the above function table that corresponds to the value of ρ. .

Therefore, the position conversion circuit 194 is specifically formed of a non-volatile memory, and stores the value of the above-mentioned inverse function 7(ρ) in a corresponding predetermined memory area using the normalized value ρ as an input address. Then, it inputs ρ and outputs the corresponding value of ΔX.

This inverse function value is K, 0≦ρ, as shown in Figure 16 (4).
It takes a value of 0≦ΔX≦Z for a value of ρ≦1. Since it is not possible to memorize the value of 7 (ρ) for all ρ, at least the curve in Figure 16 (4) is divided into equal parts (vertical axis) of KZ to obtain the desired positional resolution. Store the value of X and use the corresponding ρ as the input address.

Effect of the induced voltage correction circuit The measurement results of the relationship between the position within the small area detected in this way and the actual position within the small area of the coordinate indicator 4 are shown in the 17th.
Shown in FIGS. 18 and 19.

Here, the width Z of the small area (@shift width Z of the position sense line
) is set to 10III. Also, the 17th. Figures 18 and 19 are similar to Figures 16 and 19. The position within the small area is detected based on the polarity normalized induced voltage and the correction voltage shown in Figures 14 and 15, and the value of the detected position within the small area is the actual small area of the coordinate indicator. It is displayed as having a value of 0 to 90 for the inner position 0 to 10■.

Furthermore, the induced voltage correction circuit 199, which is a feature of the present invention,
In order to show the effect of the induced voltage correction circuit 199, the case where this induced voltage correction circuit 199 is used (with induced voltage correction in the figure) and the case where it is not used (
In the figure, the detected positions within the small region (without induced voltage correction) are also shown.

Note that when the induced voltage correction circuit 199 is not used, the two-signal converting circuit 192 uses the outputs vT, VL, VH, rLVT, nvL of the induced voltage polarity normalization circuit 198.
, treated as nvR, only VB FLvB-vB
It was treated as

FIG. 17 shows the case when the inclination of the coordinate indicator 4 is 45°,
Originally, the detected position information within the head area must be a value that changes linearly from 0 to 90 for the actual positions O to 10 of the coordinate indicator 4 within the head area. This is called an ideal value. With respect to this ideal value, if there is no induced voltage correction,
Within the small area, an error of up to 25 (approximately 5 square meters in position permutation) (hereinafter referred to as absolute reading error) occurs. On the other hand, when the induced voltage is corrected, the absolute reading error is approximately 0.2 m, which is almost close to the ideal value.

FIG. 18 shows when the inclination is 145°, and although the direction of the reading error is different, the magnitude is the same as that in FIG. 17.

FIG. 19 shows the induced voltage correction circuit 19 when the slope is 0°.
9, the absolute reading error increases, but the magnitude is extremely small.

In order to clearly show the effect of the induced voltage correction circuit 199, FIG. 20 shows how much the detected position changes depending on the inclination, with and without correction, based on the detected vehicle area position information with a 0° inclination. This shows whether there is a deviation (relative reading error).

With respect to the inclination of the coordinate indicator 4 from 0° to ±45°, there was a relative reading error of about 3 degrees without correction.
The induced voltage correction by the induced voltage correction circuit 199 reduces the relative reading error to 0.5 times and 1/6.

As explained above, the fine position detection circuit 19 adds the small area position ΔX obtained from the output of the position conversion circuit 194 and the intra-period offset value X0FF obtained from the output of the intra-period offset value calculation circuit 196 to the adder 197. Then, the intra-period position ItX, which is the position from the reference point of the periodic region, is obtained. (This situation is shown in Fig. 21.) However, as shown in Fig. 21, the position X in the period is 2
Since the process is repeated with a period of P(-8Z), the absolute position of the coordinate indicator 4 from the coordinate axis reference point cannot be determined only by the periodic position x.

In order to determine this, it is necessary to detect in which periodic region ASL the coordinate indicator 4 is located and to know the position (seating value) of the reference point R1 of that periodic region ASL.

The coarse position sense line group 61 and the coarse position detection circuit 2 detect the periodic region ksi in which the coordinate indicator 4 is located and detect the position of the reference point R1 (this is referred to as a coarse position).
This is the role of 0.

Rough position detection Since coarse position detection is not directly related to the essence of the present invention, the coarse position sense line group 61. The configuration and operation of the rough position detection circuit 20 will be briefly described.

FIG. 4 shows a laying pattern of the coarse position sense line group 61 according to the embodiment of the present invention.

As shown in the figure, the rough position sense line GL made of a t9A conductor wire in a loop shape is shifted by a width ZG −6Z<2P−
It is composed of several coarse position sense lines laid on the flat plate 6, shifted by 8Z parallel to the detection coordinate axis.

Since zG is smaller than the period 2P-8Z (width of the periodic region) of the induction characteristic of the 5KS fine position sense line as described above,
Among the induced voltages of the coarse position sense axis group 61, the maximum value coarse position sense line - which gives the maximum induced voltage is detected by the maximum value coarse position sense line detection circuit 201, thereby determining the installation position of the coarse position sense line. By, the only periodic region AS
i or two adjacent periodic regions * ASi , A
Sj++ can be detected.

The width of the coarse region detected by the maximum value coarse position sense mGm is ZG -62, which is smaller than the width 2P-8Z of the periodic region, so two adjacent periodic regions A13i and As i The values of the periodic position X in the + coarse - region do not take the same value, and the range of possible values is different.

Therefore, in advance, corresponding to the maximum value rough position sense line Gm,
A unique periodic region can be determined by providing a threshold value and comparing this threshold value with the periodic position X outputted from the fine position detection circuit 19.

The period number determination circuit 202 detects this period region,
A periodic reference point position calculation circuit 203 calculates the position of the reference point Ri of the detected periodic area ASi, and outputs a rough position Xo. The absolute position of the coordinate indicator 4 can be obtained by adding the coarse position tXO and the above-mentioned periodic position X by the adder 21.

The reason for ZG < 2 P is that due to the inclination of the coordinate indicator 4 in the area adjacent to the coarse position sense line, the magnitude of the induced voltage of the adjacent coarse position sense line is reversed - to prevent detecting an incorrect periodic area. This is because false detection can be reduced by making zG smaller than 2P.

Other Embodiment 2 The signal converting circuit 192 is not limited to calculating the two composite voltages vs t va based on the four correction voltages VT y y y y y y y vL 1 'VR and yy Combined voltage vs, Vo is VB -nVR-nVL-(26) Vo = r&VT-m1n(nVR+nVL)
-(27) However, m1n((L, b) is the 5 of α, b
It shows a smaller value.

The calculation may be simplified by calculating the normal value ρ in the normalization circuit 193 as follows.

Further, the polarity determination circuit 17. The coordinate detection circuit 1 and the control circuit 23 can be replaced by an arithmetic control section 30 as shown in FIG.

This arithmetic control section 30 includes interface circuits 31 and 34.
, a microprocessor 52 and a memory 56,
A program that defines the operation of the microprocessor 32 is stored in the memory 33. This program is executed by the polarity determination circuit 17. Coordinate detection circuit 18 and control circuit 25
It is fine as long as it performs the following actions.

Further, the induced voltage detection circuit 10 and the polarity determination circuit 17 are not limited to the configurations of the embodiments described above, and in both circuits, the magnitude of the alternating induced voltage of the sense line and the alternating induced voltage are Any device that detects whether or not it is in phase with the voltage (polarity determination) may be used.

If the alternating induced voltage v' (separately) of the sense @ S curtain and the polarity determination result are P (Si), then in the coordinate detection circuit 18, V
It goes without saying that if it is handled as (Sj) -P (No. 8).V'<si>, the same effect as in the above embodiment can be obtained.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to correct the induced voltage in the sense line, which varies depending on the inclination of the coordinate indicator, particularly the pen-shaped coordinate indicator, in accordance with the direction and degree of the inclination. Coordinate reading error due to slope K (relative value)
It has become possible to reduce this to 1/6 of the conventional value.

As a result, it is possible to expand the usable range of the inclination of the conventional coordinate indicator, reduce the burden on the user in terms of operability, and provide a coordinate reading device that is capable of inputting even fine letters in a natural handwriting style.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention, and FIG.
FIG. 5 is a block diagram of the coordinate detection circuit shown in the figure; FIG. 4 is a diagram of the sense line laying pattern of the present invention; FIG. Figure 6 is an explanatory diagram of the induced voltage characteristics of the sense machine in Figure 3, Figure 7 is a switching circuit operation timing diagram, Figure 8 is a configuration diagram of the peak timing detection circuit and polarity determination circuit, and Figure 9 is an induction voltage characteristic diagram. The operation timing diagram of the voltage detection circuit, FIGS. 10 and 11 are diagrams showing the polarity normalized induced voltage characteristics of the fine position sense line, and FIG. 12 is the configuration diagram of the induced voltage correction circuit, and FIGS. 13 and 14. . Fig. 15 is a waveform diagram showing the corrected voltage characteristics, Fig. 16 is an explanatory diagram of the operation of the fine position detection circuit, Figs. 17, 18, 1
Figures 9 and 20 show the effects of the induced voltage correction circuit.
21 is a diagram showing the relationship between a periodic region, a periodic position, an intra-period offset value, and a position within a small region, and FIG. 22 is an overall configuration diagram of another embodiment. DESCRIPTION OF SYMBOLS 1... Excitation winding drive circuit, 2... Alternating voltage generation circuit, 4... Coordinate indicator, 5-8... Flat plate, 51
．． 71...Fine position sense line group, 61.81...Coarse position sense line group, ? ... switching circuit, 10 ... induced voltage detection circuit, 15
... Sample hold circuit, 14... A/D converter, 16... Peak timing detection circuit, 17... Polarity judgment circuit, 18... Coordinate detection circuit, 19... Fine position detection circuit , 20... coarse position detection circuit, 191...
- Sense line data recording circuit, 198... Induced voltage polarity normalization circuit, 199... Induced voltage correction circuit, 192.
...2-signal conversion circuit, 193...normalization circuit,
194...Position conversion circuit, 195...Maximum value fine position sense line detection circuit, 196...Intra-period offset value calculation circuit, 30...Arithmetic control unit, ! 11.54・
...Interface 7 chair section, 32...Microprocessor, 33...Memory.・'-) Representative Patent Attorney 1I・Katsuo Kawa 3rd Figure 1C1ift 21541---6th Figure La,
RL + I reed, broom 7 Tsutsumi'! IA cause 4-kyo medical examination in Gakijima! 2 Figure l15ts Figure 1412I Figure 16 Figure I7 Figure 414 Area Eagle Signing (IlO consideration) Tower! Figure 8: Arashitan indicating lane position in the small area (kei) Figure 5: Seed mark fingernail spring position within the 4th grade area (Sail tower 20)

Claims (1)

[Scope of Claims] 1. A coordinate indicator having a flat plate on which a plurality of sense wires are laid and an excitation winding and generating an alternating magnetic field by an excitation alternating voltage supplied from an alternating voltage generating circuit; A coordinate reading device that determines the position of the coordinate indicator based on an alternating induced voltage signal induced in a wire has loop-shaped portions spaced apart by a pitch P, and currents flowing in adjacent loop-shaped portions have mutual directions. A group of four fine position sense wires made of electrical conductor wires connected in opposite directions on the flat plate and shifted by a predetermined width Z in parallel to the detection coordinate axis, the fine position sense wires an induced voltage detection circuit that sequentially scans and detects an induced voltage at a predetermined phase timing of the excitation alternating voltage signal of an alternating induced voltage signal induced in the excitation alternating voltage signal; a polarity determination circuit that detects whether or not it is in phase with the micro-position sense line; a maximum-value fine-position sense line detection circuit that detects the fine-position sense line in which the magnitude of the induced voltage is maximum among the fine-position sense line group; Based on the sense line number n of the fine position sense line S_n obtained from the position sense line detection circuit and the polarity judgment result P(S_n) of the polarity judgment circuit of this sense line,
Each fine position sense line S_i (i=
1 to 4) of the induced voltage polarity normalization circuit for normalizing the polarity of the induced voltage, at least the polarity normalized induced voltage of each fine position sense line obtained from the induced voltage polarity normalization circuit; Fine position sense line S with maximum size
Fine position sense line S_n_-_1 located to the left of _n
and fine position sense line S_n_+_1 located on the right side
an induced voltage correction circuit that corrects the polarity normalized induced voltage of each fine position sense line according to the magnitude and polarity (positive/negative) of the polarity normalized induced voltage of each fine position sense line, the magnitude of the induced voltage being maximized. A coordinate reading device characterized in that the position of the coordinate indicator is determined based on the magnitude of the induced voltage of the fine position sense line and the correction voltage obtained from the induced voltage correction circuit. 2. In claim 1, the induced voltage polarity normalization circuit is configured based on the induced voltage V(S_i) of each fine position sense line, and the sense line number n of the fine position sense line S_n having the maximum magnitude of the induced voltage. Then, based on the polarity determination result P(S_n) of the sense line, the polarity of the induced voltage of each fine position sense line S_i is determined as V_T=|V(S_n)|V_L=CPL(n)・P(S_n)・V(S_n_-
_1) V_R=CPR(n)・P(S_n)・V(S_
n_+_1)V_B=CPB(n)・P(S_n)・V
(S_n_+_2) However, CPL(n), CPR(n), and CPB(n) are polarity normalization coefficients that take a preset value of 1 or -1 corresponding to n, and when n-j<1 n-j=(n-j)+4 When n+j>4, normalize as n+j=(n+j)-4, and polarity normalized induced voltages V_T, V_L
, V_R, and V_B. 3. In claim 2, the induced voltage correction circuit comprises a polarity detection circuit that detects whether the polarity (positive/negative) of the polarity normalized induced voltage obtained from the induced voltage polarity normalization circuit is positive or negative. In preparation, when the result of the polarity detection circuit of the polarity normalized induced voltage V_B is positive, the correction amount △V is calculated by the following formula △V=[1-(V_R/V_T)]・|V_B|, and the correction voltage nV_R , nV_L is expressed by the following formula nV_R=V_
It is calculated and output as R+△V nV_L=V_L-(|V_B|-△V), and when the result of the polarity detection circuit of V_B is negative, the correction amount △V
is calculated using the following formula △V=[1-(V_L/V_T)]・|V_B|, and the correction voltages nV_L and nV_R are calculated using the following formula nV_L=V_
A coordinate reading device characterized in that it calculates and outputs L+ΔV nV_R=V_R−(|V_B|−ΔV). 4. In claim 3, when the polarity of the polarity normalized induced voltage V_B is positive and the polarity of the polarity normalized induced voltage V_R is negative, and when the polarity of V_B is negative and the polarity normalized induced voltage V_L A coordinate reading device comprising an induced voltage correction circuit that sets a correction amount ΔV to |V_B| when the polarity of is negative. 5. In claim 3 or 4, the correction voltage nV_B is calculated by the following formula nV_B=[max{nV_L, nV_R}/V_T] from the polarity normalized induced voltage V_T and the correction voltages nV_L, nV_R.
^α・min{nV_L, nV_R} However, max{
a, b} is the larger value of a, b, min{a, b
} indicates the smaller value of α and b, and α is an induced voltage correction circuit that calculates and outputs a constant constant. 6. In claim 3 or 4, the correction voltage nV_B is calculated by the following formula nV_B=[|nV_L-nV_R|/(V-min{
nV_L, nV_R})]^α・min{nV_L, n
V_R} However, min(a, b) indicates the smaller value of a and b, and α is a fixed constant that is calculated and outputted by an induced voltage correction circuit. 7. In claim 3 or 4, the polarity normalized induced voltage V_T and the correction voltages nV_L and nV_R
A coordinate reading device characterized in that the position of the coordinate indicator is determined based on the relative sizes of the three. 8. In claim 5 or 6, the polarity normalized induced voltage V_T and the correction voltages nV_L, nV_RnV
From _B, V_C=V_T+nV_L-nV_R-nV_BV_S
A coordinate reading device characterized in that two composite voltages V_C and V_S of =V_T-nV_L+nV_R-nV_B are calculated, and the position of a coordinate indicator is determined based on the relative magnitude of V_C and V_S.