JPH07134630A - Coordinate input device - Google Patents

Abstract

PURPOSE:To detect an accurate coordinate position despite the fast shift of a cursor by providing plural pieces of conductors on an input board in a matrix shape and with the prescribed spaces secured in both directions (x) and (y). CONSTITUTION:The parallel conductors 10 and 11 are provided on an input board 12 in the directions orthogonal to each other. One of body ends of each conductor 10 and 11 are connected to each other together with the other end connected to the selector means 13 and 14 respectively. A control circuit 22 controls the means 13 and forms a loop with both conductors 10-x0 and 10-x4. If the voltage of this loop is higher than a prescribed level, it is decided that a cursor 23 exists between both conductors 10-x0 and 10-x4. Then the circuit 22 controls the means 13 to successively form the loops with conductors 10-x1 and 10-x3, 10-x2 and 10-x4, and 10-x3 and 10-x5 respectively and performs measurement by three times. Then the detailed positions of the cursor 23 are calculated by these three measured voltage levels K2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate input device for detecting coordinates of a designated position indicated by an input indicator and outputting the coordinate position to an external device such as a computer.

[0002]

2. Description of the Related Art A conventional coordinate input device is disclosed in Japanese Patent Laid-Open No.
There is one disclosed in -262025. 12 and 1
The conventional technology and the principle of coordinate detection will be described with reference to FIGS. 12 is a block diagram showing a configuration of a coordinate input device according to a conventional technique, FIG. 13 (a) is a schematic diagram for explaining the principle of position detection, and FIG. 13 (b) is FIG.
FIG. 14A is a diagram showing an equivalent circuit, FIG. 14C is a vector diagram of voltages of respective portions of the equivalent circuit, and FIG. 14 is a functional diagram showing a principle of calculating a position.

First, the position detection principle of a conventional coordinate input device will be described with reference to FIGS. 13 (a), 13 (b) and 13 (c).

FIG. 13A shows a rectangular winding 1 having a width D _{1 in} the position measuring direction and a length D ₂ in a direction perpendicular to the position measuring direction.
01 and cursor 102 are shown. This winding 101
When an alternating current of frequency f is applied to the coil 101, electromagnetic coupling causes mutual coupling between the cursor 102 and the coil 101 when the cursor 102 exists above the coil 101. This mutual coupling increases the impedance of winding 101. The conventional coordinate input device measures this impedance change as a voltage change of the winding 101 and detects the position of the cursor 102 on the winding 101. Here, the cursor 102 is a circuit that is tuned to the frequency f of the alternating current applied to the winding 101. FIG. 13 (b)
Shows the equivalent circuit of FIG. FIG.
The equivalent circuit of (b) is the self-inductance L ₁ and the resistance R _{1 of} the winding 101, the self-inductance L _c of the tuning circuit of the cursor 102, the capacitance C _c and the resistance R _c , and the winding 101 and the capacitor R _c . It can be constituted by the mutual inductance M of the sol 102. In addition, the winding 101 and the cursor 102
The currents flowing in I and I are respectively I ₁ and I ₂ .

When the voltage across the winding when the cursor 102 is not present on the winding 101 is V _m , the equation (1) is established from the equivalent circuit.

V _m = R ₁ I ₁ + jωL ₁ I ₁ (1) where ω is the angular frequency of the current I ₁ , and ω = 2πf.

If the voltage across the winding when the cursor 102 is on the winding 101 is V _k , the equation (2) is established from the equivalent circuit.

V _k = R ₁ I ₁ + jωL ₁ I ₁ + jωMI ₂ (2) At this time, the equation (3) is established in the cursor 102.

[0009]

[Equation 1]

As described above, since the circuit of the cursor 102 is tuned at the frequency f, the equation (4) is established.

ΩL _c − (1 / ωC _c ) = 0 (4) By using the equations (2) to (4), the cursor 102
The voltage V across winding 101 when is on winding 101
_k can be expressed by equation (5).

V _k = {R ₁ + jωL ₁ + (ωM) ² / R _c } I ₁ (5) FIG. 13 is a vector diagram showing each of these voltages.
It is (c). The vector difference (ωM) ² I ₁ / R _c , which is the vector difference between the voltage V _m and the voltage V _k shown in FIG.
The position of 2 was detected.

Next, the position detecting operation of the conventional coordinate input device will be described with reference to the block diagram of FIG.
In FIG. 12, the conventional device has winding groups 101x and 101x.
y, a cursor 102, selectors 103 and 104, a switch 105, an amplifier 106, a detector 107, an A / D converter 108, a constant voltage source 109, a constant current source 110, and a signal source 110. There is. A large number of windings 101 described in FIG. 13A are arranged in the x direction at intervals d in the position measuring direction so as to overlap each other. This is the winding group 101
x. Similarly, a large number of windings are arranged in the y direction orthogonal to the x direction so as to overlap each other with a spacing d. This is the winding group 101y. Selector 10 from this winding group
3, 104 and the switch 105 sequentially select one winding, and apply a current of frequency f to the selected winding by the constant current source 11
Supply from 0. The amplifier 106 detects the voltage of the selected winding and outputs it to the detector 107 as the voltage e. The detector 107 detects the voltage e input from the amplifier 106,
A voltage E in synchronism with the current supplied to the winding is added and synchronous detection is performed to obtain the voltage of the real number part shown in Expression (5), which is output to the A / D converter 108. The A / D converter 108
The voltage of the real part of the equation (5) is converted into a digital value and output to an external device such as a processor (not shown). This output shows the maximum value of the voltage of one winding in each of the x direction and the y direction when the cursor 102 is on the winding. The position is calculated based on the voltage of the winding having the maximum value and the voltage values of the two windings before and after the winding.

Next, a conventional position calculation method will be described with reference to FIG. FIG. 14 is a diagram showing changes in the output voltage depending on the moving position where the cursor 102 is moved in the width direction of the winding 101 when the diameter of the cursor 102 is appropriately designed. In FIG. 14, the change in the output voltage is shown by the winding 10
When the cursor 102 is located on the center line that divides the width X of 1 into two equal parts, the output voltage becomes the maximum, and the output voltage decreases as the cursor 102 moves away from this center line. expressed. In FIG. 14, the position having the maximum value is represented as the origin. When the distance from the origin is x and the curve of the output voltage V is approximated to a quadratic curve, the detected voltage V can be expressed by equation (6).

V = a−bx ² (6) where a and b are constants.

For example, in the x direction, it is assumed that the voltage value of the winding showing the maximum value is V _k2 and the voltage values V _k1 and V _k3 before and after the voltage V _k2 . A detailed position is calculated using this value.

The voltage value V _k2 and the voltage values V _k1 and V _k3 before and after the voltage value V _k2
Can be expressed using equation (6). V _k1 is shown in formula (7), V _k2 is shown in formula (8), and V _k3 is shown in formula (9).

V _k1 = a−b (x−d) ² (7) V _k2 = a−bx ² (8) V _k3 = a−b (x + d) ² (9) Formula (7) and Formula (8) And Expressions (9) to x can be expressed by Expression (10).

[0019]

[Equation 2]

However, d is the spacing between the windings.

The coordinate position X _{p in} the winding width direction in the case where the winding having the maximum value is the Nth winding is calculated by adding the distance of N windings shifted by d and the distance x of the expression (10). It can be represented by (11).

X _p = Nd + x (11) Similarly, the coordinate value in the y direction can be calculated using the equations (10) and (11).

The conventional coordinate input device detects the position by the above operation. In the conventional device, the number of operations required to detect the position of one point is the same as the total number of each winding when the number of windings is 50 in the x direction and 50 in the y direction, for example. The number is 100 times.

[0024]

However, in the above-mentioned conventional apparatus, in order to detect the position of one point, the fixed windings are switched one by one to measure the voltage, which is necessary for the position detection. The number of operations will be the same as the total number of windings applied. Therefore, when the position of the cursor for instructing the coordinates is moved at high speed, it is possible to measure only at the time intervals for measuring the voltages of all the windings, and the time when the x coordinate value is measured and the Y coordinate are measured. There is a problem that an accurate coordinate value cannot be detected from the measured time lag.

Therefore, the present invention is to solve the above-mentioned problems, and the purpose thereof is to detect a position at high speed, and moreover, to input an accurate coordinate position even if the cursor moves at high speed. It is in the area of providing equipment.

[0026]

SUMMARY OF THE INVENTION To solve the above problems, the present invention is as follows: 1) An input indicator having a tuning circuit that tunes to a predetermined frequency and a predetermined distance in the x and y directions. It has a plurality of conductors arranged in a matrix and has the above x
Each conductor in the direction is connected at one end, each conductor in the y direction is also connected at one end, and two conductors are arbitrarily selected from the conductors in the x or y direction so as to supply a current from the outside. Magnetic coupling between the tuning circuit in the input indicator and the selected conductor by means of the input board configured as described above and a current of a predetermined frequency flowing through the two selected conductors of the input board. Therefore, a voltage is generated in the two conductors, and a position detection means for detecting a position by the voltage is provided. 2) An input indicator having a tuning circuit tuned to a predetermined frequency and a predetermined direction in the x direction and the y direction. A plurality of conductors arranged in a matrix at intervals, and each conductor in the x direction is connected at one end, and each conductor in the y direction is also connected at one end. 2 conductors of each conductor In the input indicator by an input board configured to supply a current from the outside by an arbitrary selection of the above and a current of a predetermined frequency flowing through the two selected conductors of the input board. The magnetic coupling between a tuning circuit and a selected conductor creates a voltage between the two conductors,
It has a position detection means for detecting the position by this voltage,
In the position detection method, first a conductor that detects the entire input range is selected and position detection is performed, then position detection is performed for the range specified by the position detection, and position detection is performed for the range specified by the position detection. A method of performing position detection with desired accuracy by repeating the above steps, 3) an input indicator having a tuning circuit that tunes to a predetermined frequency, and a matrix with predetermined intervals in the x and y directions. A plurality of conductors arranged in a line, and the above-mentioned x
Or, among the conductors in the y direction, three conductors are arbitrarily selected to supply an electric current from the outside, and two of the three conductors selected from the above input boards. By the magnetic coupling between the tuning circuit in the input indicator and the selected conductor by the electric current of the predetermined frequency flowing through the conductor, the conductor that is not carrying the current and the two conductors that are carrying the current are A voltage is generated, and a position detecting means for detecting a position by a peak value of a voltage obtained by adding the two voltages and a phase difference between the voltage and a current flowing through the conductor is provided, 4) to a predetermined frequency. An input indicator having a tuning circuit for tuning, a plurality of conductors arranged in a matrix at predetermined intervals in the x direction and the y direction, and the above x
Or, among the conductors in the y direction, three conductors are arbitrarily selected to supply an electric current from the outside, and two of the three conductors selected from the above input boards. By the magnetic coupling between the tuning circuit in the input indicator and the selected conductor by the electric current of the predetermined frequency flowing through the conductor, the conductor that is not carrying the current and the two conductors that are carrying the current are In the coordinate input device having a position detecting means for detecting a position by generating a voltage and detecting a position by a peak value of a voltage obtained by adding the two voltages and a phase difference between the voltage and a current flowing through the conductor, a position detecting method is provided. First, a conductor that detects the entire input range is selected and position detection is performed, then position detection is performed for the range specified by the position detection, and position detection is further performed for the range specified by the position detection. By repeating, characterized by a method of performing position detection of the desired accuracy.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A coordinate input device according to the present invention will be described below with reference to the drawings.

(First Embodiment) In the first embodiment, the other end of the winding to be detected is made common to select a winding having an arbitrary position and size, and a high-speed position is detected by area detection and detailed position detection. It is a coordinate detection device that enables detection and minimizes the deviation of the detection time of the x coordinate and the y coordinate by the detailed position detection.

FIG. 1 is a schematic block diagram showing an embodiment of a coordinate input device according to the present invention, FIG. 2 is a diagram showing details of parallel conductors, and FIG. 3 is a flow showing a flow of a position detecting method. FIG. 4 is a diagram showing details of the cursor 23 shown in FIG. 1. FIG. 5 shows the signal waveform of each part in FIG.

In FIG. 1, 10 is a parallel conductor arranged in parallel with the input board 12 at a pitch d (for example, 5 mm), and 11 is orthogonal to the parallel conductor 10 at a pitch d in the input board 12. It is a parallel conductor arranged in the direction. The parallel conductor 1 is used for detecting the position of the x coordinate, and the parallel conductor 11 is used for detecting the position of the y coordinate orthogonal to the x axis. Input button
The details of the parallel conductor 10 and the parallel conductor 11 of the cable 12 are shown. As shown in FIG. 2, the parallel conductor 10 has 10-x0 to 10
There are 51 lines up to -x50, one end is connected to each other, and the other end is connected to the selection means 13. Similarly for the parallel conductor 11, from 11-y0 to 11-
There are 51 lines up to y50, which are connected to each other at one end, and the selecting means 14 is connected to one end which is not connected.
The selecting means 13 and 14 shown in FIG. 1 select three arbitrary parallel conductors 10 and 11 respectively. 15
Is a switch circuit, and selects either the selection means 13 or 14. 16 is a signal generation circuit, which has a frequency f
A sinusoidal current I ₁ (eg 300 KHz) is generated. 17
Is a signal detection circuit, which detects the voltage V ₁ from the selected two parallel conductors, synchronously detects it with the current I _1, and outputs it as the voltage V ₃ of the real part. Reference numeral 18 denotes a full-wave rectifier circuit, which full-wave rectifies the voltage V ₃ . A low-pass filter (LPF) 19 converts the voltage K ₁ obtained by full-wave rectification into a DC voltage (DC voltage) K ₂ and outputs it to the control circuit 22. A control circuit 22 receives a voltage from the LPF 19 and controls the selection circuits 13 and 14 and the switch circuit 16. Further, the control circuit 22 performs input / output with an external device such as a computer. Specifically, the position detection accuracy is input from an external device, and the coordinate value of this accuracy is output to an external device such as a computer. The position detecting means for performing the position detecting operation is composed of selecting means 13 and 14, a switch circuit 15, a signal generating circuit 16, a signal detecting circuit 17, a full-wave rectifying circuit 18, an LPF 19, and a control circuit 22.

Reference numeral 23 is a cursor, and the tuning circuit 7
Built in. The tuning circuit 7 is composed of an inductor 24 and a capacitor 25 which are formed by winding a magnetic material such as ferrite. The ferrite has a cylindrical shape with a diameter of 6 mm and a length of 15 mm, for example, and a winding of 100 turns is applied to the ferrite to form the inductance 24.

The difference between the coordinate input device of the present invention constructed as above and the conventional example is the following two points. Masu 1
The point is that in the prior art example of FIG. 9, the windings are arranged independently, whereas in the embodiment of the present invention, a plurality of parallel conductors are arranged at a pitch d, and By connecting one end of each to each other and opening the other end, the size of the winding can be changed at an integer multiple of the pitch d of the parallel conductors.

The second point is that, in the conventional example, the windings are sequentially selected to perform the position detection, whereas in the present invention, the position detection method is a region detection in which the input region is roughly divided,
This is to perform the two-step detection of the detailed position detection for detecting the position smaller than the pitch of the parallel conductors.

The operation of area detection and the operation of detailed position detection, which are different from the conventional one, will be described below with reference to the block diagram of FIG. 1 and FIG.
This will be described in more detail with reference to the flowchart of FIG.

First, the operation of area detection will be described.

The control circuit 22 controls the switch circuit 15 and connects the selecting means 13 and the signal generating circuit 16. Next, the control circuit 22 controls the selection means 13 to form a loop composed of the parallel conductors 10-x0 and 10-x4. The current I ₁ generated by the signal generating circuit 17 flows through this loop. The signal detection circuit 17 measures the voltage V _k of this loop and outputs the current I ₁ input from the signal generation means 16.
Is detected synchronously and converted into the voltage V _M of the real part of the equation (5) and output to the full-wave rectifier circuit 18. The full-wave rectifier circuit 18 full-wave rectifies the voltage V _M output from the signal detection means 17,
The voltage is set to K ₁ and output to the LPF 19. LPF19 is
The high frequency component of the voltage K ₁ is removed and a direct current voltage K ₂ is output to the control circuit 22. The control circuit 22 receives the DC voltage K ₂ and compares it with a constant voltage K _r . The control circuit 22 controls the parallel conductor 10 when the voltage K ₂ is larger than the voltage K _r.
If it is determined that there is a cursor 23 between −x0 and 10-x4, and the voltage K ₂ is smaller than the voltage K _r , the cursor 23 is placed between the parallel conductors 10-x0 and 10-x4. Judge not to.

Next, the control circuit 22 controls the selecting means 13 to form a loop composed of parallel conductors 10-x2 and 10-x6. After forming the loop, the control circuit 22 receives the voltage K ₂ by the same operation as described above,
Compare with constant voltage K _r . When the voltage K ₂ is larger than the voltage K _r , the control circuit 22 determines that the cursor 23 exists between the parallel conductors 10-x2 and 10-x6, and the voltage K 2
_When voltage K ₂ is smaller than _r , parallel conductor 10-x2
It is judged that there is no cursor 23 between 10 and 10-x6.

Similarly, the control circuit 22 controls the selection means 13 to form a loop composed of a set of two parallel conductors and a previously selected parallel conductor. After forming the loop, the control circuit 22 performs the voltage K by the same operation as described above.
₂ is received and compared with a constant voltage K _r . Control circuit 22
, When big voltage K ₂ than the voltage K _r is mosquito between pairs of parallel conductors - is determined that there is Sol 23, when the voltage K ₂ is smaller than the voltage K _r is the parallel conductors It is determined that there is no cursor 23 between the pair. In the case of an example having 51 parallel conductors, the operation of detecting a voltage is repeated 25 times after forming one loop described above. By this operation, the parallel conductor pitch 2d (10m
The control circuit 22 can detect whether or not the cursor 23 exists in the partial area between m).

Similarly, also in the y direction, the same operation as the x direction is repeated 25 times, and y out of (250 mm) in the entire y direction is y.
The control circuit 22 can detect whether or not the cursor 23 is present in the partial area between the parallel conductor pitches 2d (10 mm) in the direction.

The above-described operation is the area detection operation, and the control circuit 22 performs the detection operation 25 times in the x-direction and 25 times in the y-direction, a total of 50 times, and the pitch d of the parallel conductors is 2
It is possible to detect the presence of the cursor 23 in a square area of double size. In the area detection explained, the set of parallel conductors selected has a pitch of 4d (20 mm) such as 10-x0 and 10-x4, but it is not limited to the pitch of 4d, and the pitch of 3d or 5d is also possible. Similar operation is possible. However, if the number of parallel conductors is increased, high-speed area detection is possible, but the output voltage decreases, and if the number of parallel conductors is decreased, the number of detection operations increases. Therefore, in this embodiment, the number of parallel conductors to be selected is three.

Next, the operation of detailed position detection will be described.

The detailed position detection is obtained by measuring the voltage value of the loop before and after the area detected by the area position detection and calculating this voltage value. As an example, the case where the control circuit 22 detects that the cursor 23 is between the parallel conductors 10-x2 and 10-x4 and between the parallel conductors 11-y2 and 11-y4 by the above area detection will be described in detail. The position detection operation will be described.

First, the operation of obtaining coordinate values in the x direction will be described.

The control circuit 22 controls the switch circuit 15 to connect the selecting means 13 and the signal generating means 16. The control circuit 22 controls the selecting means 13 and controls the parallel conductors 10-x.
1 and 10-x3 to form a loop. After forming the loop, the control circuit 2 is operated by the same operation as described above.
2 receives the voltage K ₂ . The voltage value of this K ₂ is V _k1 . Next, the control circuit 22 controls the selecting means 4 to form a loop composed of the parallel conductors 10-x2 and 10-x4. After forming the loop, the control circuit 22 receives the voltage K ₂ by the same operation as described above. The voltage value of this K ₂ is V _k2 . Next, the control circuit 22 controls the selecting means 13 to form a loop composed of the parallel conductors 10-x3 and 10-x5. After forming the loop, the control circuit 22 receives the voltage K ₂ by the same operation as described above. The voltage value of K ₂ is V _k3 .

By the above three measurements, the control circuit 22
Can obtain voltage values V _k1 , V _k2 , and V _k3 . By substituting these three voltage values into the equations (10) and (11), the detailed position X _p can be measured.

Next, the operation of obtaining the coordinate values in the y direction will be described.

With respect to the coordinate value in the y direction, the voltage values V _k1 , V _k2 and V _k3 are obtained by the same operation as the operation in the x direction. By substituting these three voltage values into the equations (10) and (11), the detailed position Y _p can be obtained.

The x-coordinate X _p and the y-coordinate Y _p can be obtained by the above six operations. As is clear from the above description, the coordinate input device of the present invention performs the area detection operation 50 times. Detailed position detection operation The position detection for one point is completed by a total of 56 times of six operations. According to the conventional technique, the number of windings is 5 for both the x-axis and the y-axis in the same winding conversion as in the present embodiment.
The number of operations required for position detection is 10 in this case.
It was 0 times. When the position detection with the same accuracy as the conventional one is performed while the cursor 23 is stopped, the apparatus of the present invention performs a total of 56 measurement operations (56% of the conventional number). Further, in the device of the present invention, the number of operations is proportional to the reciprocal of the number of parallel conductors, and therefore, it is clear that the number of position detection operations is further reduced when the number of conductors is increased.

Further, in the apparatus of the present invention, the detailed position detection operation is performed three times in the y direction immediately after three measurements in the x direction. Therefore, even when the cursor 23 moves at high speed. ,
The time difference between the detection of the x-direction coordinate and the detection of the y-direction coordinate is 1/25 on average in the conventional example. Therefore, the position detection accuracy of the device of the present invention is 25 times better than that of the conventional device.

The flow of the operation of the area detection and the detailed position detection described above is shown as a flow chart in FIG. First, the entire input area is divided into areas, and the area detection operation is performed to detect that the input indicator 23 is present in this area. (Step 30
1) If the detection voltage equal to or higher than the constant level V _r cannot be detected, the area detection operation is repeated again. (Step 302)
When there is a detection voltage equal to or higher than a certain level V _r, a set of parallel conductors before and after the region where the voltage is measured is selected, and detailed position detection operation is performed in which measurement is performed three times in the x direction and three times in the y direction. . (Step 303) In the measurement result, a set of parallel conductors in a region where a detection voltage equal to or higher than a constant level V _r is present is selected, and it is determined whether or not the detection result measured on the x-axis and the y-axis is the required accuracy. (Step 304) This operation is repeated to detect the position of the cursor 12 with the required accuracy. The detected coordinate values are output to an external device such as a computer. (Step 305) FIG. 4 is a diagram showing details of the cursor 23 used in the present invention. The cursor 23 includes a pen shaft 41 that allows a magnetic flux of synthetic resin or the like to pass through, a ferrite 42 and a winding 43 inside the pen shaft 41,
It is composed of capacitors 44 and 45. The ferrite 42, the winding 43 wound around the ferrite 42, and the capacitors 44 and 45 constitute the tuning circuit 7. Ferrite 42
Has a conical shaped portion in a portion where a winding having a diameter of 6 mm and a length of 15 mm is provided so as to enter the inside of the pen tip of the pen shaft 41 for collecting magnetic flux. The capacitor 45 is a variable capacitor and is used for adjustment to set the resonance frequency to f.

(Second Embodiment) In the first embodiment, two parallel conductors are selected to form one loop. In the second embodiment, by selecting three parallel conductors to form two loops, it is possible to perform position detection at a higher speed than in the first embodiment. Example 2 will be described with reference to the drawings.

FIG. 6 is a view for explaining the position detection principle of the coordinate input device of the present invention, and FIGS. 7 and 8 are views (a) showing the positions of the input indicator and the conductor, respectively. (B)
Is a vector diagram of the detected voltage.

First, the principle of position detection of the coordinate input device of the present invention will be described with reference to FIG. FIG. 6A is a schematic diagram showing the position detection principle, and FIG. 6B is a diagram showing an equivalent circuit of FIG. 6A. In FIG. 6A, reference numerals 1, 2 and 3 are conductors arranged in parallel and have the same impedance. One end of the parallel conductors 1, 2, 3 4, 5, 6
Is a terminal, and the other ends are connected to each other. 7
Is a tuning circuit provided at the tip of the input indicator, for example. A current I ₁ is applied to the parallel conductor 1, and a current I ₁ is applied to the parallel conductor 3.
A current I ₂ is flowing. The current I ₁ and the current I ₂ are sine waves having the same frequency and amplitude but different phases by 180 degrees. The terminal 5 of the parallel conductor 2 arranged in the center is grounded. The tuning circuit 7 is composed of, for example, a coil wound around a ferrite core and a capacitor, and its inductance and capacitance have values tuned to the frequency of the current flowing through the parallel conductors 1 and 3. The voltage generated between the terminals 4 and 5 is V ₁ , the voltage generated between the terminals 6 and 5 is V _2, and the voltage obtained by adding the voltage V ₁ and the voltage V ₂ is V ₃ .

FIG. 6B shows an equivalent circuit of FIG. 6A. In the figure, the resistance and inductance of the loop formed by the parallel conductors 1 and 2 are R ₁ and L ₁ , respectively, and the resistance and inductance of the loop formed by the parallel conductors 2 and 3 are R ₂ and L, respectively. _Shown in ₂ . The mutual inductance of the inductances L ₁ and L ₂ is M ₁₂ . The currents I ₁ and I ₂ flowing in the parallel conductors 1 and 3 are given by the constant current sources 8 and 9. The inductance, capacitance and winding resistance of the tuning circuit 7 correspond to the inductance L ₃ , capacitance C ₃ and resistance R ₃ , respectively. Mutual inductances when there is magnetic coupling between the inductances L ₁ and L ₂ and the tuning circuit 7 are M ₁₃ and M ₂₃ , respectively.

Using the equivalent circuit of FIG. 6 (b), the voltage of each part is determined for the case where the tuning circuit is not located between the parallel conductors 1 and 3 and the case where it is present. First, let us consider voltages at respective parts when the tuning circuit 7 is not located between the parallel conductors 1 and 3, that is, when there is no influence of the mutual inductances M ₁₃ and M ₂₃ .

Since the current I ₁ is flowing in the parallel conductor 1 and the current I ₂ is flowing in the parallel conductor 2, the voltage V ₁ and the voltage V ₂ are given by the formula (1
It can be expressed by 2) and equation (13).

V ₁ = R ₁ I ₁ + jωL ₁ I ₁ + jωM ₁₂ I ₂ (12) V ₂ = R ₂ I ₂ + jωL ₂ I ₂ + jωM ₁₂ I ₁ (13) where ω is the current I ₁ and I ₂ Is the angular frequency of
2πf.

The voltage V which is the total voltage of the voltage V ₁ and the voltage V _2.
3 can be expressed by equation (14).

[0059]

[Equation 3]

Since the parallel conductors 1, 2 and 3 are made of the same material, their impedances are equal, and R ₁ =
R ₂ , L ₁ = L _2, and the current I ₁ and the current I
_The frequency ₂ has the same frequency f, the same amplitude, and the phase is different by 180 degrees, so that I ₁ = −I ₂ (15). Therefore, the voltage V ₃ when the tuning circuit 7 is not present in the position between the parallel conductors 1 and ₃ is V ₃ = 0 (16) from the equation (14).

Next, the added voltage V ₃ when the tuning circuit 7 is located between the parallel conductors 1 and ₃ is obtained. Since the voltage V ₁ and the voltage V _{2 at} this time include the influence of mutual inductance, the voltage of each loop is expressed by the equations (17) and (18).

[0062]

[Equation 4]

[0063]

[Equation 5]

Here, the current flowing through the tuning circuit 7 is set to I ₃
I am trying.

In the tuning circuit 7, the equation (19) is established from the relationship of the voltage of each part.

[0066]

[Equation 6]

Since the tuning circuit tunes to the frequency f, the following conditions are satisfied.

ΩL ₃ − (1 / ωC ₃ ) = 0 (20) From the formulas (15) and (19) and the formula (20) of the tuning condition, the current I3 can be expressed as the formula (21).

I ₃ = −jω {M ₁₃ −M ₂₃ } I ₁ / R ₃ (21) Since impedances of the parallel conductors 1, 2 and 3 are equal, R ₁ = R ₂ and L ₁ = L ₂ is there. From the above formula and conditions, the voltage V
₃ can be expressed by equation (22).

[0070]

[Equation 7]

From the equation (16), the voltage V ₃ is constituted by the mutual inductance M ₁₃ between the tuning circuit 7 and the loop constituted by the parallel conductors 1 and 2, and the tuning circuit 7 and the parallel conductors 2 and 3. Le - a mutual inductance M ₂₃ between the flop, it can be seen that determined by the value of the resistance R ₃ and the current I ₁ of the tuning circuit 7. That is, when the peak value of the voltage V ₃ is measured, it is possible to measure the voltage value due to the mutual inductance, which is not affected by the self-inductance and the resistance value of the parallel conductors. The measurement of this voltage V ₃ makes it possible to detect the presence of the tuning circuit 7 between the parallel conductors 1 and 3.

In the present invention, the tuning circuit 7 further includes a parallel conductor 1.
It can be determined from the phase of the voltage V ₃ whether it is in the position between 2 and 2 or in the position between the parallel conductors 2 and 3.

Determination of whether the tuning circuit 7 is between the parallel conductors 1 and 2 or between the parallel conductors 2 and 3 will be described with reference to FIGS. 7 and 8. 7 (a) and 8 (a) are diagrams showing the positional relationship between the parallel conductors and the tuning circuit, and FIG. 7 (b) and FIG.
(B) is a vector diagram showing the phase of the detected voltage V ₃ .

When the tuning circuit 7 is located between the parallel conductors 1 and 2 as shown in FIG. 7A, the mutual inductances M ₁₃ and M ₂₃ have the relationship of the expression (17).

M ₁₃ >> M ₂₃ ≈0 (17) Therefore, the voltage V ₃ obtained from the equation (16) has the same positive phase as the current I ₁ . The voltage V ₃ at this time is shown in FIG.
It shows in (b).

When the tuning circuit 7 is located between the parallel conductors 2 and 3 as shown in FIG. 8A, the mutual inductances M ₁₃ and M ₂₃ have the relationship of the expression (18).

0 ≈ M ₁₃ << M ₂₃ (18) Therefore, the voltage V ₃ obtained from the equation (16) has a phase different from the current I ₁ by 180 degrees. The voltage V ₃ at this time is shown in FIG. When the tuning circuit 7 is provided between the parallel conductors 1 and 2 and when the tuning circuit 7 is provided between the parallel conductors 2 and 3, the phase of the voltage V ₃ is different by 180 degrees. By detecting that the phase of the voltage V ₃ is 180 degrees different, whether the tuning circuit 7 is located between the parallel conductors 1 and 2 as in the case of FIG. As in the case, it can be determined whether the tuning circuit 7 is located between the parallel conductors 2 and 3.

That is, the voltage V ₃ is measured, and the presence of the tuning circuit 7 between the parallel conductors 1 and 3 is detected by the magnitude of the peak value of the voltage, and the phase is the same as the current I _1. It is possible to detect whether the tuning circuit 7 is at a position between the parallel conductors 1 and 2 or the tuning circuit 7 is at a position between the parallel conductors 2 and 3 depending on whether the tuning circuit 7 is different by 180 degrees. In the conventional technique, only one position can be detected by one detection operation, but in the present invention, two positions can be detected by one detection operation.

An embodiment of the coordinate input device of the present invention embodied based on the principle described above will be described with reference to FIGS. 9, 10, and 3. FIG. 9 is a block diagram showing an outline of one embodiment of the present invention, FIG. 10 is a diagram showing waveforms of respective parts in the block diagram of FIG. 9, and FIG. 3 is a flow chart showing a flow of position detection. Is.

In FIG. 9, 10 is a parallel conductor which is arranged in parallel to the input board 12 at a pitch d, and 11 is arranged in the input board 12 at a pitch d in a direction orthogonal to the parallel conductor 10. It is a parallel conductor provided. The parallel conductor 10 is used for detecting the position of the x axis in the figure, and the parallel conductor 11 is used for detecting the position of the y axis orthogonal to the x axis. The parallel conductor 10 is 1
There are 51 lines from 0-x0 to 10-x50, which are connected to each other at one end, and the selection means 13 is connected to one end which is not connected. Similarly for the parallel conductor 11,
There are 51 lines from 11-y0 to 11-y50, which are connected to each other at one end, and the selecting means 14 is connected to one end which is not connected. The selection means 13 and 14 select any three parallel conductors of the parallel conductors 10 and 11, respectively. Reference numeral 15 is a switch circuit, and selecting means 13 and 14
Select either. 16 is a signal generation circuit,
A sinusoidal current I ₁ of frequency f and the phase of this current I ₁ are 1
Generate currents I ₂ that differ by 80 degrees. Reference numeral 17 denotes a signal detection circuit, which detects the voltage V ₁ and the voltage V ₂ from the selected three parallel conductors, adds the voltages V ₁ and V ₂ , amplifies them, and outputs them as the voltage V ₃ . Reference numeral 18 denotes a full-wave rectifier circuit, which has a voltage V ₃
Full-wave rectify. 19 is a low pass filter (LPF)
The full-wave rectified voltage V ₃ is converted into a DC voltage (DC voltage) K ₂ and output to the control circuit 22. A phase difference detector 20 detects the phase difference between the current I ₁ and the voltage V ₃ . A low pass filter (LPF) 21 converts the detected phase difference into a DC voltage. Reference numeral 22 is a control circuit, which receives the voltage from the LPFs 19 and 21 and controls the selection circuits 13 and 14 and the switch circuit 15. Further, the control circuit 22 performs input / output with an external device such as a computer. Specifically, the position detection accuracy is input from an external device, and the coordinate value of this accuracy is output to an external device such as a computer. The position detecting means for performing the position detecting operation is the detection selecting means 13 and 14, the switch circuit 15,
Signal generation circuit 16, signal detection circuit 17, full-wave rectification circuit 1
8, LPF 19, phase difference detector 20, LPF 21, and control circuit 22.

Reference numeral 23 is an input indicator, which incorporates the tuning circuit 7. The tuning circuit 7 is composed of an inductor 24 and a capacitor 25 which are formed by winding a magnetic material such as ferrite.

The difference from the first embodiment is that the phase comparator 20 and the LPF 2 for phase comparison with the point where three parallel conductors are selected.
The point is 1.

The operation of the coordinate input device of the present invention configured as described above will be described below with reference to the block diagram of FIG. 9 and FIG.
This will be described in more detail with reference to the signal waveform diagram of 0. The device of the present invention detects the position of the input indicator 23 by the input board 1.
The two-stage operation of the area detecting operation for detecting which area of 2 and the detailed position detecting operation for detecting the position between the parallel conductors is performed.

First, the area detecting operation will be described.

The control circuit 22 controls the switch circuit 15 and connects the selection circuit 13 and the signal generation circuit 16. Next, the control circuit 22 controls the selecting means 13 so that the current I ₁ output by the signal generating circuit 16 is applied to the parallel conductor 10-.
It poured into x0, electric current I ₂ to the parallel conductors 10-x8, grounding the parallel conductors 10-x4. The signal detection circuit 17 is connected to the switch circuit 15 and connected to the parallel conductor 10-x0.
The voltage V ₁ generated between the parallel conductor 10-x4 and the parallel conductor 10-x4 and the voltage V ₂ generated between the parallel conductor 10-x8 and the parallel conductor 10-x4 are measured. The voltage V ₁ and the voltage V ₂ are the currents I ₁ and I, respectively.
_The waveform has a phase advance of Δt ₁ and Δt ₂ from ₂ .
Is shown in. The signal detection circuit 17 adds the voltages V ₁ and V ₂ and amplifies them to obtain a voltage V _{3, which} is the full-wave rectification circuit 1
Output to 8. The voltage V ₃ has a waveform synchronized with the current I ₁ and is shown in FIG. The full-wave rectifier circuit 18 has a voltage V
₃ is full-wave rectified and output to the LPF 19 as a signal K ₁ . L
The PF 19 removes the high frequency component of the frequency component of the signal K ₁ , and D
Let C voltage be K ₂ . The voltage level of the voltage K _{2 at} this time is V
_{Let x} . In the control circuit 22, if the voltage level V _x exceeds the level V _r , the input indicator 23 causes the parallel conductor 10-.
and from x0 between 10-x8, if not exceed the level V _r, This position, it is determined that there is no input indicator 23.

When the voltage V ₃ exceeds the level V _r , that is, the input indicator 23 causes the parallel conductors 10-x0 to 10-.
When it is determined that the position is between x4, the phase difference detector 2
0 receives the current I ₁ from the signal generating circuit 16 and the voltage V ₃ from the signal detecting circuit 17. The current I ₁ is supplied to the phase difference detector 2
Within 0, the digital signal N ₁ is synchronized at the zero crossing points of the rising and falling edges of the sine wave. The voltage V3 is
In the phase difference detector 20, the digital signal N ₂ is synchronized at the zero cross points of the rising and falling edges of the sine wave. Exclusive OR (EX__) of the digital signals N ₁ and N ₂
OR) to obtain the output voltage N ₃ . This output voltage N
₃ includes switching noise due to a slight phase shift between the digital signals N ₁ and N ₂ . The LPF 21 removes the switching noise in the output voltage N ₃ from the phase difference detector 20 and outputs a DC voltage N ₄ .

In FIG. 10, the illustrated V ₃ ,
The waveforms of N ₂ , N ₃ and N ₄ are parallel conductors 10-x0 to 10
Between -x4 indicates if there is an input indicator 23, V ₃ depicted _{', N 2', N 3} ', N 4' is waveform, while the parallel conductors 10-x4 of 10-x8 The case where there is the input indicator 23 is shown.

If the phase of current I ₁ and voltage V ₃ is the same, DC
The level V _p of the voltage N ₄ is close to 0 volt, and when the phases of the current I ₁ and the voltage V ₃ are 180 degrees different from each other, the level V _p ′ of the DC voltage N ₄ is close to the high level voltage of the digital signal.

The control circuit 22 receives the DC voltage N ₄ and
If this voltage level V _p does not exceed the level V _pr ,
The input indicator 23 is provided on the side of the parallel conductors 10-x0 to 10-x4.
If V _p exceeds the level V _pr , it is assumed that there is the input indicator 23 on the parallel conductors 10-x4 to 10-x8 side.

By the above operation, is there an input indicator 23 between the parallel conductors 10-x0 and 10-x4?
It is possible to detect whether there is the input indicator 23 between 10 and 10-x8.

However, the parallel conductors 10-x0, 10-x4, 10-x are also used in the present invention as in the prior art.
The input indicator 23 cannot be detected directly above 8. This principle will be described with reference to FIG. FIG. 11 is a diagram showing a magnetic field strength distribution when a current is passed through the conductor. Figure 11
FIG. 11B shows a current I ₁ flowing through the conductor 1 as shown in FIG.
Is a magnetic field strength distribution perpendicular to the x-axis direction when the current flows, and the position of the conductor in FIG. 11A is the origin. This magnetic field strength distribution has opposite directions with the conductor sandwiched, and there is a place where the magnetic flux becomes 0 in the coil of the tuning circuit 7. Therefore, the voltage V ₃ = 0. Further, just above the parallel conductor 10-x4, the mutual inductances M ₁₃ and M ₂₃ with the tuning circuit 7 are substantially equal to each other, and the voltage V ₃ = 0 from the equation (16).
Therefore, the parallel conductors 10-x0, 10-x4, 10-x
Directly above 8, the input indicator 23 cannot be detected.

However, when a large number of parallel conductors are arranged as shown in FIG. 9, the parallel conductors 10-x4, 1 which cannot be measured are measured.
Directly above 0-x8 are parallel conductors 10-x2, 10-x6.
The input indicator 23 can be detected by using 10-x10. Next, a method of detecting the input indicator 23 directly above the parallel conductors 10-x4 and 10-x8 will be described.

The control circuit 22 controls the selection means 13,
A current I ₁ is applied to the parallel conductor 10-x2, so that the parallel conductor 10-
x6 grounded, electric current I ₂ to the parallel conductors 10-x10. After the selection, the voltage K ₂ and the voltage N ₄ are obtained by the same operation as described above.

The control circuit 22 controls the level V _{x of} this voltage K _2.
However, if it exceeds the level V _r , it is assumed that the input indicator 23 is between the parallel conductors 10-x2 and 10-x10, and the level V
_{If r} is not exceeded, the input indicator 23
Judge that there is no. If the input indicator 23 is present, the control circuit 22 receives the DC voltage N ₄ and if the voltage level V _p does not exceed the level V _pr , the parallel conductor 10-
If there is an input indicator 23 on the 10-x5 side from x2, V
_{If p} exceeds the level V _pr , it is assumed that the input indicator 23 is located on the side of the parallel conductors 10-x6 to 10-x10.

Therefore, the position directly above the parallel conductors 10-x4 and 10-x8 can be detected by measuring using a set of parallel conductors that are displaced by a constant distance as described above. Furthermore, when the results of the above two measurements are combined,
The control circuit 22 includes a parallel conductor 10-x0 and a parallel conductor 10-x0.
x2, parallel conductor 10-x2 and parallel conductor 10-x4,
Between parallel conductor 10-x4 and parallel conductor 10-x6, between parallel conductor 10-x6 and parallel conductor 10-x8, parallel conductor 10-x
It is possible to determine which of the five sections between the parallel conductor 10 and the parallel conductor 10-x10 has the input indicator 23.

By the above-mentioned two measuring operations, the position of the five sections from the parallel conductors 10-x0 to 10-x10 of the x-axis can be detected. The same operation as this operation is performed by the parallel conductors 10-x8 to 10-x18, 10-x16 to 1
0-x26, 10-x24 to 10-x34, 10-x
32 to 10-x42, 10-x40 to 10-x50
Up to 6 times. 2 times in the x direction by the above 12 operations
It is possible to detect whether or not the input indicator 23 is present in the area divided into five.

Next, with respect to the y-axis, the region detection operation of the region divided into 25 in the y direction is similarly performed by the operation of 12 times.

In the above area detecting operation, the presence of the input indicator 23 within the interval of the pitch 2d in the x and y directions is detected by 24 times of detecting operations.

Next, the detailed position detecting operation will be described.

As an example, it is assumed that it can be determined by the area detection operation that the input indicator 23 exists between the parallel conductors 10-x2 and 10-x4 and between the parallel conductors 11-y2 and 11-y4. Within this area, three voltage values are measured, and a detailed coordinate position is detected from the measured values, not whether the input indicator 23 is present or not.

The operation of detecting the detailed coordinate position will be described below.

First, the operation of obtaining coordinate values in the x direction will be described.

The control circuit 22 controls the switch circuit 15 to connect the selection means 13 and the signal generation means 16. The control circuit 22 controls the selecting means 13 and controls the parallel conductors 10-x.
1 in electric current I _1, electric current I ₂ to the parallel conductors 10-x3, grounding the parallel conductors 10-x5. Unlike the previous selection of parallel conductors, the center of the three parallel conductors is not grounded, but the end parallel conductors are grounded. After selecting the parallel conductors, the same operation is performed, and the control circuit 22 obtains the voltages K ₂ and N ₄ . The detected voltage K _{2 in} this case is a voltage due to the mutual inductance between the parallel conductor 10-x1 and the input indicator 23 when the parallel conductor 10-x3 forms a loop. The voltage level of the detected voltage K ₂ in this case is V _k1 . Next, the control circuit 22 controls the selection means 13 to cause the parallel conductor 10-
x2 electric current I _1, the electric current I ₂ to the parallel conductors 10-x4, grounding the parallel conductors 10-x6. The voltage level of the detected voltage K ₂ in this case is V _k2 . Next, the control circuit 22 controls the selection means 13 to make the parallel conductors 10-x.
3 to electric current I _1, electric current I ₂ to the parallel conductors 10-x5, grounding the parallel conductors 10-x7. The voltage level of the detected voltage K ₂ in this case is V _k3 . A detailed coordinate value X _p is obtained by substituting these three values into the equations (10) and (11) described in the prior art.

Next, the operation for obtaining the coordinate values in the y direction will be described.

The control circuit 22 controls the switch circuit 15 and connects the selecting means 14 and the signal generating means 16. The control circuit 22 controls the selecting means 14 and controls the parallel conductors 11-y.
1 in electric current I _1, electric current I ₂ to the parallel conductors 11-y3, grounding the parallel conductors 11-y5. Unlike the previous selection of parallel conductors, the center of the three parallel conductors is not grounded, but the end parallel conductors are grounded. After selecting the parallel conductors, the same operation is performed, and the control circuit 22 obtains the voltages K ₂ and N ₄ . The voltage level of the detected voltage K ₂ in this case is V _k1 .
Next, the control circuit 22 controls the selection means 14, a current flows I ₁ parallel conductors 11-y2, electric current I ₂ to the parallel conductors 11-y4, grounding the parallel conductors 11-y6. The voltage level of the detected voltage K ₂ in this case is V _k2 .
Next, the control circuit 22 controls the selection means 14, a current flows I ₁ parallel conductors 11-y3, electric current I ₂ to the parallel conductors 11-y5, grounding the parallel conductors 11-y7. The voltage level of the detected voltage K ₂ in this case is V _k3 .
These three values are given by the equations (10) and (1
By substituting into 1), a detailed coordinate value Y _p is obtained.

Detailed coordinates X _p and Y _p can be obtained by the above six measurement operations.

In the second embodiment, the position detection of one point is completed by a total of 30 operations including the area detection operation 24 times and the detailed position detection operation 6 times. Further, when the pitch d of the parallel conductors is equal to the winding pitch of the conventional device, the device of the present invention can detect the position with the same accuracy as the conventional device.

Next, a comparison with the conventional device will be made. In the conventional technology, if the number of windings is 50 on both the x-axis and the y-axis, 1
The measurement operation of 00 times was required. However, in the device of the present invention, when the region sandwiched by two parallel conductors is converted into one winding, the number of parallel conductors on the x-axis and the y-axis is 51, which is the same as the conventional example. It can be the same as for lines. In this case, the apparatus of the present invention can detect the position with the same accuracy as that of the conventional apparatus by a total of 30 times of measurement operations (30% of the number of times of the related art). Further, in the device of the present invention, the number of operations is proportional to the reciprocal of the exponential function of the parallel conductors. Therefore, when the number of conductors is increased in order to improve the detection accuracy, the number of position detection operations becomes smaller than in the conventional case. Is clear.

Further, in the device of the present invention, the detailed position detection operation is performed three times in the y direction immediately after three measurements in the x direction. Therefore, even when the input indicator 23 moves at high speed. , The time difference between the detection of the x-direction coordinate and the detection of the y-direction coordinate is 1/25 of the average of the conventional example. Therefore, the position detection accuracy of the device of the present invention is 25 times better than that of the conventional device.

A method of selecting parallel conductors in the position detection described above is shown as a flow chart in FIG. First, the entire input area is divided into areas, and the area detection operation is performed to detect that the input indicator 23 is present in this area. (Step 301) If the detection voltage above the constant level V _r cannot be detected, the region detection operation is repeated again. (Step 302) If there is a detected voltage above a certain level V _r , select a set of parallel conductors before and after the region where the voltage is measured, and measure the detailed positions three times on the x-axis and three times on the y-axis, respectively. Perform detection operation. (Step 303) In the measurement result, a set of parallel conductors in a region where a detection voltage equal to or higher than a constant level V _r is present is selected, and it is determined whether or not the detection result measured on the x-axis and the y-axis is the required accuracy. (Step 304) This operation is repeated to detect the position of the input indicator 23 with the required accuracy. The detected coordinate values are output to an external device such as a computer. (Step 30
5) In the above examples, in order to measure directly above the parallel conductor,
Parallel conductors were selected that were ½ the distance between the initially selected parallel conductors. However, it suffices if there is a parallel conductor used for the next measurement between the selected parallel conductors.
You are not bound by the double distance.

Further, it goes without saying that the measurement accuracy can be made variable by changing the interval for selecting the parallel conductors.

[0112]

As is apparent from the above description, the coordinate input device of the present invention can detect a position at a higher speed than conventional ones.

Further, by simply adding the two voltages detected from the three parallel conductors, an extra means for detecting the detected voltage synchronously with the current and detecting the real part of the voltage is unnecessary, unlike the prior art. become.

Further, it is possible to provide a coordinate input device capable of arbitrarily setting the detection accuracy which could not be obtained by the conventional technique.

[Brief description of drawings]

FIG. 1 is a block diagram of a coordinate input device according to an embodiment of the present invention.

FIG. 2 is a diagram showing details of parallel conductors of an input board.

FIG. 3 is a flowchart showing a position detecting method.

FIG. 4 is a diagram showing details of an input indicator.

FIG. 5 is a diagram showing signal waveforms at various portions.

FIG. 6 is a schematic diagram showing a position detection principle of the coordinate input device of the present invention and a diagram showing an equivalent circuit.

FIG. 7 is a diagram showing a position when there is a tuning circuit between two parallel conductors of three parallel conductors and a vector diagram of a detection voltage.

FIG. 8 is a diagram showing a position when there is a tuning circuit between two parallel conductors of three parallel conductors, and a vector diagram of a detection voltage.

FIG. 9 is a block diagram of a coordinate input device according to an embodiment of the present invention.

FIG. 10 is a diagram showing signal waveforms at various points.

FIG. 11 is a diagram showing a magnetic field strength distribution.

FIG. 12 is a block diagram showing an example of a conventional technique.

FIG. 13 is a diagram for explaining a detection principle of a conventional technique.

FIG. 14 is a function diagram showing a principle of calculating a cursor position according to a conventional technique.

[Explanation of symbols]

 7 Tuning circuit 8, 9 Constant current source 10 Parallel conductor (for x-axis measurement) 11 Parallel conductor (for y-axis measurement) 12 Input board 13 Selection means (for x-axis measurement) 14 Selection means (for y-axis measurement) 15 switch circuit 16 signal generator 17 signal detector 18 full-wave rectifier 19 low pass filter (LPF) 20 phase difference detector 21 low pass filter (LPF) 22 control circuit 23 input indicator

Claims (4)

[Claims] 1. An input indicator having a tuning circuit that tunes to a predetermined frequency, and a plurality of conductors arranged in a matrix at predetermined intervals in the x direction and the y direction,
The conductors in the x-direction are connected at one end, and the conductors in the y-direction are also connected at one end. Two conductors in the x- or y-direction are arbitrarily selected and a current is externally supplied. A tuning circuit in the input indicator and a selected conductor by means of an input board configured to supply and a current of a predetermined frequency flowing through the two selected conductors of the input board. A coordinate input device characterized in that a voltage is generated in two conductors by magnetic coupling and a position detecting means for detecting a position by the voltage is included. 2. An input indicator having a tuning circuit that tunes to a predetermined frequency, and a plurality of conductors arranged in a matrix at predetermined intervals in the x direction and the y direction,
The conductors in the x-direction are connected at one end, and the conductors in the y-direction are also connected at one end. Two conductors in the x- or y-direction are arbitrarily selected and a current is externally supplied. A tuning circuit in the input indicator and a selected conductor by means of an input board configured to supply and a current of a predetermined frequency flowing through the two selected conductors of the input board. A voltage is generated in two conductors by magnetic coupling, and a position detecting means for detecting the position by the voltage is provided. First, the position detecting method is performed by selecting a conductor for detecting the entire input range. Then, the position detection is performed for the range specified by the position detection, and the position detection is further performed for the range specified by the position detection, thereby performing the position detection with desired accuracy. A coordinate input device characterized by the above. 3. An input indicator having a tuning circuit that tunes to a predetermined frequency, and a plurality of conductors arranged in a matrix at predetermined intervals in the x and y directions,
Further, among the conductors in the x or y direction, three conductors are arbitrarily selected to supply an electric current from the outside, and three selected conductors of the input board. 2 of
By the magnetic coupling between the selected conductor and the tuning circuit in the input indicator by the current of a predetermined frequency flowing through the two conductors, a conductor that is not carrying current and two conductors that are carrying current are provided. A voltage is generated at the position, and the position input means has a position detecting means for detecting the position by the peak value of the voltage obtained by adding the two voltages and the phase difference between the voltage and the current flowing through the conductor. apparatus. 4. An input indicator having a tuning circuit that tunes to a predetermined frequency, and a plurality of conductors arranged in a matrix at predetermined intervals in the x and y directions,
Further, among the conductors in the x or y direction, three conductors are arbitrarily selected to supply an electric current from the outside, and three selected conductors of the input board. 2 of
By the magnetic coupling between the selected conductor and the tuning circuit in the input indicator by the current of a predetermined frequency flowing through the two conductors, a conductor that is not carrying current and two conductors that are carrying current are provided. A voltage is generated at the position, and the position detection means has a position detection means for detecting the position by the peak value of the voltage obtained by adding the two voltages and the phase difference between the voltage and the current flowing through the conductor. First, a conductor for detecting the entire input range is selected and position detection is performed, then position detection is performed for the range specified by the position detection, and position detection is further performed for the range specified by the position detection. According to the coordinate input device, a method for detecting a position with desired accuracy is provided.