JPH0621975B2 - Coordinate reading device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a coordinate reading device that detects a coordinate value of a cursor by an electromagnetic coupling method.

(Prior Art and Problems to be Solved by the Invention) Conventionally, as a device of this type, the waveform amplitude of the induced voltage generated in the magnetic flux detection coil of the cursor or the conductor loop of the electric insulating plate is AD converted. There is a method in which the coordinate value of the cursor is detected by, and a method in which the coordinate value of the cursor is detected by measuring the time until the phase of the induced voltage is inverted.

However, in the former case, the magnitude of the induced voltage changes when the cursor moves away from the electrical insulating plate, so some means for correcting the height of the cursor is required, while in the latter case, the height correction means for the cursor like the former does not. Although it is not necessary, since the coordinates are detected by measuring the time, changes in the constants due to the temperature of the circuit components used directly affect the accuracy, so both of them are difficult and expensive to read highly accurate coordinates. It had the drawback of becoming

In addition, there are times when it is desired to input data or the type of processing at the same time as coordinate input, but in the past, the switch was turned on when inputting coordinates, or the switch was turned on automatically by pressing the cursor on the board. Coordinates are generally input, and few can simultaneously input information other than coordinates. There are some cursors provided with some switches so that they can be selected at the time of inputting coordinates, but in this case, there are drawbacks that the cursor is large and the operability is poor.

(Object of the Invention) The present invention has been proposed in view of the above points, eliminates the drawbacks of the above-described conventional example, does not employ cursor height correction means and time measurement means, and is highly accurate and inexpensive. With the object of providing a coordinate reading device capable of not only configuring the device but also detecting the writing pressure of a cursor formed in a pen shape, and inputting the data or the type of processing at the same time as the coordinate input. There is.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a first conductor loop for the X axis, which is arranged in parallel in a zigzag pattern with a period P on the surface of an electrical insulating plate, and A second conductor loop that is arranged in parallel with the first conductor loop with a P / 4 period offset from the first conductor loop; and a cosine function of the output voltage waveform amplitude connected to the first conductor loop and having a variable a And a cosine function oscillating means connected to the second conductor loop, the waveform amplitude of the output voltage changing in proportion to the sine function of the variable a, and the cosine function oscillating means, A pen-shaped cursor that has a built-in magnetic flux detection coil for detecting the magnetic flux generated from the conductor loop excited by the sine function oscillating means, and the distance between the electric insulating plate and the magnetic flux detection coil is variable according to the writing pressure. And the zigzag When the distance from the left end of the first conductor loop in the shape of a circle to the center of the cursor is a variable and the voltages applied to both ends of the first and second conductor loops are cos2πa / P; -sin2πa / P, respectively, The voltage ax at both ends of the magnetic flux detection coil Acos ωt · sin [2π (x-a) / P] is increased or decreased by a and the value ax when the phase is inverted is used as the coordinate value of the cursor, and the detected variable is set to a predetermined value. And a processing means for exciting the first and second conductor loops to detect the magnitude of the voltage induced in the magnetic flux detecting coil as a pen writing pressure. A gist of the invention is a coordinate reading device characterized by the above.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings illustrating an example.

FIG. 1 is a block diagram showing an embodiment of the coordinate reading device of the present invention. In the figure, reference numeral 3 is a cursor that points to a position to be input, and is formed in a pen shape as shown in FIG. 2 so that it can be grasped and used by a hand. As a configuration, a magnetic flux detection coil 3b is provided at the tip of a cylindrical pen body 3a, and a core material 3c is arranged inside the pen body 3a to provide a spring.
The tip of the core material 3c is made to project from the tip of the pen body 3a by 3d, and the projection amount of the core material 3c changes according to the writing pressure when the pen body 3a is held in the hand and pressed against the electric insulating plate 4. Then, the distance between the magnetic flux detecting coil 3d and the electric insulating plate 4 is changed.

Returning to FIG. 1, reference numeral 4 denotes an electric insulating plate. As shown in FIG. 3, the electric insulating plate 4 has the X-coordinate detecting conductor loop 4a on the front side and the Y-coordinate detecting conductor loop 4b on the back side. It is provided by printing orthogonally so that two-dimensional coordinate reading is possible. Since the X and Y coordinate detecting conductor loops 4a and 4b have the same configuration, the X
Only the coordinate detecting conductor loop 4a will be described, and the description of the Y coordinate detecting conductor loop 4b will be substituted by the description of the X coordinate detecting conductor loop 4a.

The X-coordinate detecting conductor loop 4a is configured as shown in FIG. 4 (A), and the X-coordinate detecting conductor loop 4a has an electric conductor wire 1 (Xcos wire) and an electric conductor wire as shown in FIG. Two
(Xsin wires) are alternately folded back at the same pitch P / 2, and are arranged in parallel on the same plane so that there is a shift of P / 4 pitch between the electric conductor wire 1 and the electric conductor wire 2. Forming a loop.

In this conductor loop 4a, now E _ab · sin between the terminals ab
When an AC voltage of E _cd · sin ωt is applied between ωt and the terminal cd for excitation, a voltage E _ef approximately represented by the following equation is induced between the terminals ef of the cursor 3 having the built-in magnetic flux detection coil 3b. .

E _ef = A ・ E _ab・ cos ωt ・ sin2π ・ x / P + A ・ E _cd・ cos
ωt · cos2π · x / P (1) In the above equation, A represents the coupling coefficient between the conductor loop 4a and the cursor 3, and x represents the distance from the center of the cursor 3 to the b line.

Here, when E _ab and E _cd are set to a voltage value represented by the following equation E _ab = cos2π · α / P (2) E _cd = sin2π · α / P (3) with α as a variable, ( The induced voltage E _ef expressed by the following equation (4), which is arranged by substituting the equations (2) and (3) into the equation (1), is induced in the magnetic flux detection coil 3b of the cursor 3.

E _ef ≈ A · cosωt · sin [2π (x−α) / P] (4) From this equation (4), when α is increased or decreased, x−α = nP (n = 0,
1, 2, ...), the induced voltage E _ef becomes 0V. Further, it can be seen that the phase is also inverted at the boundary of x-α = nP. That is, the phase of the induced voltage E _ef is increased by cosω by increasing α.
When α is inverted from t to −cosωt, or α when α is reduced and the phase of the induced voltage E _ef is inverted from −cosωt to cosωt is α _x , this α _x is within the periodic range P.
(In FIG. 4 (A), the period, that is, the pitch is P,
Positions in P, such as A, B, C, and D, are referred to as a periodic region. )
Therefore, the coordinate value x = α _x + nP of _x can be calculated by detecting this α _x and n determined by which period region the cursor 3 is located. The present invention is based on such a basic principle.

In addition to the current feedback lines F-E-a and I-H-c of the conductor loop 4a shown in FIG.
G-a and I-J-c are provided, and feedback currents I _E-a and I _H-c are provided.
The generated magnetic fluxes φ _Ea and φ _Hc by the feedback currents I _FG and I
_The magnetic fluxes φ _FG and φ _IJ generated by _I-J are canceled as indicated by the arrows, and the distortion of the magnetic flux due to the current feedback line is reduced so that the degree of approximation of the equation (4) is increased.

Further, as shown in FIG. 4 (A), lead wires connected to the electric conductor wires 1 and 2 of the conductor loop 4a at _one ends of the current switches S _{1 to} S ₄ via diodes D _{-1 to} D _-8. By providing and increasing / decreasing the excitation area of the period P by operating the current switches S _{1 to} S ₄ , it is possible to determine which period from the magnitude and phase of the waveform amplitude of the voltage E _ef induced in the magnetic flux detection coil 3b of the cursor 3. It is configured to be able to detect whether the cursor 3 is located in the area. At that time, the following measures are taken. That is, FIG. 4 (A)
As shown in, V + cos2πα / P ・ sinωt, which is obtained by adding AC voltage cos2πα / P ・ sinωt, −sinπα / P ・ sinωt to DC voltage V of 1/2 or more of the maximum amplitude, to excite the conductor loop 4a. , V-sin πα / P · sin ωt, and an exciting region can be increased or decreased by using a diode and a transistor, which are inexpensive DC current switches, without using an expensive AC current switch. In addition, since only the AC component is induced in the magnetic flux detection coil 3b of the cursor 3,
It does not affect the equation (4).

On the other hand, in FIG. 1, 6 and 7 are changeover switches composed of a transistor and an IC, which are activated by the X and Y coordinate detection signal X _s output from the microcomputer 16 and the detection signal X _s is LOW (0 V). When the X coordinate detection conductor loop 4a (Xcos
Line, Xsin line), and when HIGH (+ 5V), the Y coordinate detecting conductor loop 4b (Ycos line, Ysin line) is excited.

Next, 8 and 9 are multiplication type D / A converters, which respectively receive the digital signals of cos2πα / P and -sin2πα / P generated by the microcomputer 16 and input the two-phase oscillator (si).
It is multiplied by the output sinωt (analog value) of the oscillator 13 that generates two voltage waveforms of n waveform and cos waveform, and this is multiplied by the DC voltage V (half of the maximum waveform swing of sinωt is diode D
_{−1 to} D ₋₈ , which is obtained by adding the drop voltage when the transistor array 10 is turned on) to generate an analog signal of V + cos2πα / P · sinωt, V−sinπα / P · sinωt, and the changeover switches 6 and 7 are generated. Is output to. The digital signals cos2πα / P and −sin2πα / P are not generated by calculation in order to speed up the program processing in the microcomputer 16, but are increased / decreased in units of the program corresponding to the variable α. A numerical table of cos2πα / P and −sin2πα / P is stored, and the numerical table is referred to and output each time α is increased or decreased.

Next, 10 is a transistor array, which is a period detection signal S ₁ ′ to S ₄ ′ generated by the microcomputer 16.
Input, and when the input signal is HIGH signal (+ 5V), switch the corresponding current switches S _{1 to} S ₄ to the signal ground.
It is designed to conduct to SG. Further, reference numeral 11 is a widening device, which widens the induced voltage E _ef generated in the cursor 3. Next, 12 is a synchronous rectifier (synchronous signal input, for example, a rectifier that rectifies alternating current to direct current in synchronization with a pulse voltage that is periodically generated), and the magnetic flux detection coil 3b of the cursor 3 which is widened by the widening device 11. The induced voltage E _ef is output from the two-phase oscillator 13 cosωt
Synchronous rectification by and output to the voltage comparators 14 and 15. 2
The phase oscillator 13 outputs sinωt and cosωt.

Further, the voltage comparator 14 compares the reference voltage 0V with the induced voltage E _ef ′ (output of the synchronous rectifier 12) of the magnetic flux detection coil 3b of the cursor 3 after the synchronous rectification, and when the reference voltage 0V is higher, it becomes HIGH. When the signal (+ 5V) is low, a LOW signal (0V) is output to the microcomputer 16. Also, voltage comparator
Reference numeral VREF is set to a voltage close to the reference voltage VREF (a voltage close to the negative maximum voltage of the induced voltage E _ef 'of the magnetic flux detection coil 3b of the cursor 3 after synchronous rectification) and the magnetic flux detection coil 3b of the cursor 3 after synchronous rectification. compared with the induced voltage E _ef 'of the reference voltage VREF
HIGH signal (+ 5V) when is higher, LOW when is lower
The signal (0V) is output to the microcomputer 16.

Reference numeral 17 denotes an AD converter, which inputs the output of the synchronous rectifier 12, that is, the induced voltage E _ef ′ of the magnetic flux detection coil 3b of the cursor 3 after the synchronous rectification, and outputs a digital value corresponding to the amplitude to the microcomputer 16 It is designed to output to.

The microcomputer 16 has a coordinate detection processing program and a writing pressure detection processing program built-in, and inputs output signals from the voltage comparators 14 and 15 and the AD converter 17 to input a digital signal cos2πα / P,- It outputs sin2πα / P, the periodic range detection signals S ₁ ′ to S ₄ ′, and the X and Y coordinate detection signal X _s . That is, when the output of the voltage comparator 14 is LOW, that is, when the induced voltage E _ef of the magnetic flux detection coil 3b of the cursor 3 is cosωt, the coordinate detection processing program of the microcomputer 16 increases α by incrementing / decrementing unit. , When the phase is inverted (when the output of the voltage comparator 14 becomes HIGH), the addition is stopped and the output of the voltage comparator 14 becomes HIGH on the contrary.
When the signal is generated, that is, when the induced voltage E _ef of the magnetic flux detection coil 3b of the cursor 3 is −cosωt, α is subtracted in increments / decrements to reduce the phase and the phase is inverted (the output of the voltage comparator 14 is L
When it becomes OW), the subtraction is stopped. Also, after α is detected, the magnetic flux detection coil 3b of the cursor 3
In order that the induced voltage E _{ef of} is a constant voltage level regardless of the location, a value obtained by adding a predetermined value to α is set instead of α, and when the output of the voltage comparator 15 is low, The detection signals S ₁ ′ to S ₄ ′ are sequentially switched to the transistor array 10 and output. Conversely, when the output of the voltage comparator 15 is a HIGH signal, the switching is stopped at the signal position at this time, and this specific signal is output. It is designed to be remembered. In addition, the range of the increment / decrement unit of the variable α is set to P / 16, for example, so that the increment / decrement unit does not exceed the period P. When increasing α, 0, P / 16, 2
P / 16, ... 15P / 16,0, P / 16,2P / 16, ... and when decreasing α, 0,15P / 16,14P / 16,
...... 0,15P / 16,14P / 16, ...

In addition, the writing pressure detection processing program is started after the coordinates are detected by the above coordinate detection processing program, and a value obtained by adding a predetermined value to the detected α is set as α to excite the conductor loop. The output of the A / D converter 17 is taken in as a writing pressure detection signal to determine the level.

Next, the operation of the above embodiment will be described by taking the case where the cursor 3 is located at the solid line position in FIG. 4 (A) as an example.

When coordinate detection processing program of the microcomputer 16 is activated, the first microcomputer 16 X, in the LOW the Y-coordinate detection signal X _s output to the change-over switches 6 and 7,
The conductor loop 4a for X coordinate detection (XCOS line, Xsin line) is excited.

Next, the variable α is set to α = 0 to generate cos0, −sin0, and the digital signal is output from the microcomputer 16 to the DA converters 8 and 9.

The DA converter 8 multiplies cos0 (digital value) and the output sinωt (analog value) of the two-phase oscillator 13 to generate an AC voltage cos0 · sinωt, and adds DC voltage V to this to obtain V + cos0 · sinωt. Output to the changeover switch 6.

On the other hand, the DA converter 9 multiplies -sin0 (digital value) and the output sinωt (analog value) of the two-phase oscillator 13 to generate an AC voltage -sin0 · sinωt, and the DC voltage V is added to this. V-sin0 · sinωt is output to the changeover switch 7.

Since the X, Y coordinate detection signal X _s has already been LOW (0 V), the X coordinate detection conductor loop 4a (Xcos
Line, Xsin line) and the magnetic flux detection coil of the cursor 3
The induced voltage E _ef is generated in 3b. This induced voltage E _ef is the first
In the figure, the signal is amplified by the amplifier 11 and output to the synchronous rectifier 12. The synchronous rectifier 12 outputs the output cosωt of the two-phase oscillator 13.
At the same time, the induced voltage E _ef is synchronously rectified and E _ef ′ is output. When the cursor 3 is at the solid line position in FIG. 4 (A), E _ef ′ is the fourth
The induced voltage at the point C in the figure (B), the phase of -cosωt,
That is, it becomes a negative voltage. The voltage comparator 14 uses this induced voltage E
Compare _ef 'with 0V. In this case, 0V is higher, so
It outputs a HIGH signal to the microcomputer 16. Since the coordinate detection processing program of the microcomputer 16 is configured to subtract by the increment / decrement unit P / 16 when the output of the voltage comparator 14 is HIGH, α / 16 is subtracted from α = 0, and α is α = 15P / 16. Then, as in the case of α = 0, the digital signals cos2π · 15/16 and −sin2π · 15/16 are output from the microcomputer 16 and V + (cos2π · 15/16) · sinωt, V− (sin2π · 15/16) · sinωt, the conductor loop 4a (Xcos, X) for detecting the X coordinate of the electric insulating plate 4
(sin) is excited, and the induced voltage E _ef ′ at point B in FIG. 4 (B) is output to the synchronous rectifier 12. The induced voltage E _ef ′ is −co
Since the phase of sωt is a negative voltage, the HIGH signal is output from the voltage comparator 14 to the microcomputer 16, and α
Is performed, and α becomes α = 14P / 16. Such a subtraction operation of α is repeated, and α is α = 10P / 16 = 5
At P / 8, the induced voltage E _ef ′ at point A is output to the synchronous rectifier 12 as shown in FIG. 4 (B), and the phase of −cos ωt is inverted to the phase of cos ωt, that is, the induced voltage E _ef. ′
Is inverted from a negative voltage to a positive voltage, and the voltage comparator 14
The W signal is output to the microcomputer 16, the subtraction operation of α is stopped, and the coordinate value α _{x in} the periodic region of the cursor 3 is α _x
= 5P / 8 is detected.

When the detection of α _x is finished, 5P / 8 + P / 4 = 7P / 8 obtained by adding P / 4 to α _x = 5P / 8 is set to α, and the digital signal cos2π · 7 is set in the same manner as the coordinate detection operation in the periodic region. / 8, −sin2π · 7/8 is output from the microcomputer 16 and V + (cos2π · 7/8) · sinωt V− (sin2π · 7/8) · sinωt is the conductor loop for detecting the X coordinate of the electrical insulating plate 4. 4a (Xcos line,
(Xsin line) is excited and the induced voltage E _ef ′ of the magnetic flux detection coil 3b of the cursor 3 is synchronously rectified by the output cosωt of the two-phase oscillator 13, and the position x of the cursor 3 changes, as shown in FIG.
The voltage change E _ef ′ as shown in (C) is obtained, and x = 5P / 8 and x
At the position of = 5P / 8 + P, the induced voltage E _ef ′ is negative and maximum (the phase is −cosωt and the amplitude is maximum). This maximum position does not change even if the excitation area is increased or decreased. Therefore, while maintaining this state, the microcomputer 16 outputs the periodic area detection signals S ₁ ′ to S ₄ ′ to S ₁ ′, S ₂ ′, S ₃ ′. , S ₄ ′
The voltage comparator 15
Is checked whether it is a HIGH signal, that is, whether the induced voltage E _ef of the magnetic flux detection coil 3b of the cursor 3 is in the phase of −cosωt and the waveform amplitude is close to the maximum.

This will be described in more detail as follows. First, only the period detection signal S ₁ ′ is set to HIGH and output to the transistor array 10. As a result, only the current switch S ₁ becomes conductive with the signal ground SG, and the diode D
_The electric conductor wire connected to _-2 is excited. In this state, since the cursor 3 is not in the excitation region, the induced voltage E _ef of the magnetic flux detection coil 3b of the cursor 3 is small, and the output E _ef ′ of the synchronous rectifier 12 does not become lower than VREF, so the voltage comparator 15 is LOW. The signal is output to the microcomputer 16. In the microcomputer 16, after outputting the period detection signal S ₁ ′, the output of the voltage comparator 15 is LOW, so next, only the period detection signal S ₂ ′ is made HIGH and is output to the transistor array 10. . As a result, only the current switch S ₂ is brought into conduction with the signal ground SG, and even the electric conductor line connected to the diode D _-4 is excited. This time, the cursor 3 is in the excitation region, and the voltage E _ef having the maximum waveform amplitude is induced in the magnetic flux detection coil 3b of the cursor 3 at the phase of −cos ωt. Therefore, the induced voltage E _ef ′ after synchronous rectification is Since it becomes lower than VREF, the voltage comparator 15 outputs a HIGH signal to the microcomputer 16. After outputting the period detection signal S ₂ ′,
Since the output of the voltage comparator 15 is HIGH, the microcomputer 16 stores S ₂ ′. alpha _x value from the period the region coordinates alpha _x of FIG. 4 of the (A) Since it can be seen that it is in the area of And S ₂ ′, it is determined that the cursor 3 is located in the periodic region P ₀ , and the X coordinate x is calculated as x = 5P / 8 + 0.

Similarly, when the cursor 3 is at the position indicated by the chain line in FIG. 4 (A), E _ef ′ becomes the maximum negative value when the current switch S ₄ is turned on, so that the cursor 3 is positioned in the periodic region P ₁ . Therefore, the X coordinate x is calculated as x = 5P / 8 + P. In this way, the detection of the X coordinate is completed.

When the detection of the X coordinate is completed, the X, Y coordinate detection signal X _{s of} the microcomputer 16 becomes HIGH, whereby the Y coordinate detecting conductor loop 4b (Ycos line, Ysin line) is excited,
The Y coordinate is detected by the same operation as the detection of the X coordinate.
By detecting the X coordinate and the Y coordinate in this way,
The coordinate value of the cursor 3 is detected.

Next, in the writing pressure detection processing program, the above X
Either α or α found in the detection of the coordinates or the Y coordinate is used, and a predetermined value such as P / 4 is added to this to obtain a waveform at the maximum amplitude, as in FIG. 4 (C). Then, in the cursor 3, as shown in FIG. 2, the protrusion amount of the core material 3c changes according to the writing pressure, and the magnetic flux detection coil 3b and the conductor loop are
Since the distance from the electric insulating plate 4 provided with 4a and 4b changes, the coupling coefficient A in the equation (4) changes, and the amplitude of the induced voltage of the magnetic flux detection coil 3b of the cursor 3 changes according to the writing pressure. Therefore, the amplifier 11 and the synchronous rectifier 12,
Data indicating the writing pressure is obtained by a digital value through the A / D converter 17, and this is taken in by the microcomputer 16. Then, in the microcomputer 16, it is discriminated into several ranks according to the level and treated as information indicating the type of data or processing.

In the above embodiment, for the sake of simplicity, the increment / decrement unit of the variable α is P / 16 and the period range is two periods. However, these are merely examples, and any of them is arbitrary. It goes without saying that it can be set to

(Effects of the Invention) As described above, according to the present invention, a first conductor loop for the X-axis, which is arranged in parallel in a zigzag pattern with a period P on the surface of the electrical insulating plate, and the first conductor loop. A second conductor loop arranged in parallel with the first conductor loop with a P / 4 period offset, and the waveform amplitude of the output voltage connected to the first conductor loop changes in proportion to the cosine function of the variable a. A cosine function oscillating means, a sine function oscillating means connected to the second conductor loop, in which the waveform amplitude of the output voltage changes in proportion to the sine function of the variable a, and the cosine function oscillating means and the sine function oscillating means. A built-in magnetic flux detection coil for detecting the magnetic flux generated from the excited conductor loop, a pen-shaped cursor in which the distance between the electric insulating plate and the magnetic flux detection coil is variable according to the writing pressure, and the zigzag shape Of the first conductor loop When the distance from the left end to the center of the cursor is a variable a, and the voltage applied to both ends of the first and second conductor loops is cos2πa / P; -sin2πa / P, the voltage that appears at both ends of the magnetic flux detection coil of the cursor. A cos ωt · sin [2π (x-a) / P] is used as the coordinate value of the cursor when the phase is inverted by increasing or decreasing a, and the coordinate value is determined by adding a predetermined numerical value to the detected variable. And a processing means for exciting the first and second conductor loops and detecting the magnitude of the voltage induced in the magnetic flux detection coil as pen writing pressure. The device can be configured with high accuracy and at low cost without using the height correction means and the time measurement means. Furthermore, by changing the writing pressure of the cursor formed in a pen shape, there is an effect that data or a type of processing can be input at the same time as the coordinate input.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the coordinate reading device of the present invention, FIG. 2 is a diagram showing an example of the configuration of a cursor, and FIG.
4A, 4B, and 4C are exploded views showing the arrangement relationship of the conductor loops for detecting the X and Y coordinates in the electric insulating plate.
Is a diagram showing an electric conductor wire forming an X coordinate detecting conductor loop and its output voltage waveform, FIG. 5 is a view for explaining the operation of a current feedback line in the conductor loop, and FIG. 6 is FIG.
It is a figure for demonstrating the conductor loop before forming the conductor loop of (A). 1, 2 ... Electrical conductor wire, 3 ... Cursor, 3a ... Pen body, 3b ... Magnetic flux detection coil, 3c ... Core material, 3d ... Spring,
3e ... Code, 4 ... Electrical insulating plate, 4a ... X coordinate detection conductor loop, 4b ... Y coordinate detection conductor loop, 6, 7 ...
... Changeover switch, 8, 9 ... DA converter, 10 ... Transistor array, 11 ... Amplifier, 12 ... Synchronous rectifier, 13
…… Two-phase oscillator, 14, 15 …… Voltage comparator, 16 …… Microcomputer, 17 …… AD converter

Claims (4)

[Claims] 1. A first conductor loop for the X-axis, which is arranged in parallel in a zigzag pattern with a period P on the surface of an electric insulating plate, and the first conductor loop.
Second conductor loop which is arranged in parallel with the first conductor loop by being shifted by P / 4 period from the first conductor loop, and the waveform amplitude of the output voltage connected to the first conductor loop is a cosine function of the variable a. A cosine function oscillating means that changes in proportion, and the second
Connected to the conductor loop and the waveform amplitude of the output voltage changes in proportion to the sine function of the variable a, and a magnetic flux generated from the conductor loop excited by the cosine function oscillating means and the sine function oscillating means. A built-in magnetic flux detection coil for detecting, a pen-shaped cursor in which the distance between the electric insulating plate and the magnetic flux detection coil is variable according to the writing pressure, and the left end of the zigzag-shaped first conductor loop. When the distance to the center of the cursor is a variable and the voltages applied to both ends of the first and second conductor loops are cos2πa / P; −sin2πa / P, the voltage that appears at both ends of the magnetic flux detection coil of the cursor Acosωt · sin The value a _x when the phase is inverted by increasing or decreasing a from [2π (x−a) / P] is used as the coordinate value of the cursor, and the detected variable is set to a predetermined value. And a processing means for exciting the first and second conductor loops to detect the magnitude of the voltage induced in the magnetic flux detecting coil as a pen writing pressure. A coordinate reading device. 2. A cursor is provided with a magnetic flux detection coil at the tip of a cylindrical pen body, and a core material is arranged inside the pen body so that the tip of the core material is a spring of the pen body. The coordinate reading device according to claim 1, wherein the coordinate reading device is configured so as to project from the tip portion, and the projecting amount of the core material changes according to the writing pressure. 3. A switch is provided for each of the first and second conductor loops, the switches are alternately switched to pass a current, and the position of the cursor is sequentially determined by the strength of the voltage generated in the magnetic flux detection coil of the cursor. The coordinate reading device according to claim 1, further comprising means for determining. 4. Two sets of X-coordinate conductor loops formed on the surface of the electric insulating plate, and 2 arranged on the back surface of the electric insulating plate and orthogonal to the first conductor loop.
The coordinate reading device according to claim 1, further comprising a set of Y-coordinate conductor loops.