JP2583502B2 - Position detection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a position detecting device for detecting a designated position of a cordless position indicator.

(Prior Art) As a conventional position detecting device, a pulse current is applied to a driving coil provided at one end of a magnetostrictive transmission medium or at a tip of a position indicator to generate a magnetostrictive vibration wave in the magnetostrictive transmission medium. The time until the induced voltage based on the magnetostrictive vibration wave is detected by the detection coil provided at the tip of the position indicator or at one end of the magnetostrictive transmission medium is measured by a processing device or the like, and the designated position of the position indicator is calculated based on the measured time. There was something to do.

Further, as another conventional position detection device, a plurality of drive lines and detection lines are arranged orthogonally to each other, a current is sequentially passed through the drive lines, and the detection lines are sequentially selected to detect an induced voltage. In some cases, a position designated by a position indicator having a magnetic material as described above is detected from the position of a detection line where a large induced voltage is induced.

(Problems to be Solved by the Invention) Although the former device has relatively good position detection accuracy,
A code is required between the position indicator and the processing device to transmit and receive timing signals, etc., and handling thereof is significantly restricted. Had to be used in close proximity.

Also, in the latter device, the position indicator can be cordless, but the resolution of the coordinate position is determined by the interval between the lines, and if the interval between the lines is reduced to increase the resolution, the S / N ratio and stability will deteriorate, and therefore It is difficult to increase the resolution, it is difficult to detect the position just above the intersection of the drive line and the detection line, and there is a problem that the position indicator must be brought very close to the line.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a device which has good operability because a position indicator is not connected anywhere and can detect a designated position of the position indicator with extremely high accuracy.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, a signal is exchanged between a position indicator and a tablet, and a coordinate value on the tablet indicated by the position indicator is detected. A position detecting device, comprising: a first tuning circuit which is normally closed and indicates a position to be measured to a tablet; and a tablet having a tuning frequency different from that of the first tuning circuit which is constituted by an operation of an operator. , A position indicator having a second tuning circuit for instructing the position to be measured and notifying the operation, and a plurality of loop coils, and the first and second tuning circuits can be tuned. A tablet having radio wave generating means for always generating a radio wave of a constant magnetic field strength and radio wave detecting means for detecting a radio wave caused by the tuning reflected from the first or second tuning circuit; The position indication is performed regardless of whether or not the operation has been performed with a finer accuracy than an arrangement interval of the plurality of loop coils, based on a plurality of induced voltages induced by the reflection in a plurality of loop coils constituting the radio wave detecting means. A radio wave reflected from the position indicator to the tablet by an induction voltage induced by the reflection in a loop coil constituting the radio wave detecting means; Proposes a position detecting device comprising: a tuning circuit discriminating means for detecting which of the first and second tuning circuits is a radio wave reflected from the first and second tuning circuits and detecting an operation state of the position indicator.

(Operation) According to the present invention, when a radio wave having a constant magnetic field strength is always generated from the radio wave generation means composed of a plurality of loop coils of the tablet, the radio wave is transmitted to the position indicator of the position indicator for specifying the position on the tablet. The first or second tuning circuit that tunes to the first or second tuning circuit, that is, receives the radio wave, emits the same radio wave and immediately reflects it. The first or second
The radio wave attributable to the tuning reflected from the tuning circuit is detected by radio wave detecting means comprising a plurality of loop coils of the tablet, and the position indicator is irrespective of whether or not the operation is performed by the coordinate calculating means. The coordinate value of the designated position on the tablet is calculated with a precision smaller than the interval between the plurality of loop coils, and the radio wave reflected from the position indicator to the tablet by the tuning circuit discriminating means is the first signal. Alternatively, it is detected which one of the second tuning circuits the radio wave is reflected from, and the operation state of the position indicator is detected.

(Embodiment) FIG. 1 shows a first embodiment of a position detecting device according to the present invention. In FIG. 1, 1 is a position detecting unit, 2 is a selection circuit, 3 is a transmission / reception switching circuit, and 4 is a position indicator. Reference numeral 5 indicates a transmission circuit, reference numeral 6 indicates a reception circuit, and reference numeral 7 indicates a processing device.

In the position detecting section 1, a plurality of, for example, 48 loop coils 11-1, 11-2,..., 11-48 having conductors parallel to each other are indicated by arrows A in the figure (hereinafter referred to as position detecting directions). ). Further, each of the loop coils 11-1 to 11-
48 are arranged so as to be parallel to each other and overlap each other.
Although each of the loop coils 11-1 to 11-48 has one turn here, it may have a plurality of turns if necessary. As the position detecting unit 1, a plurality of parallel conductors formed by, for example, etching a well-known printed circuit board or the like and connecting them with jumper wires or the like to form the plurality of loop coils is used. Can be.

The selection circuit 2 includes the plurality of loop coils 11-1 to 11-
One of the loop coils is sequentially selected from 48. One end of each of the loop coils 11-1 to 11-48 is connected to one terminal group 21, and the other end is connected to another terminal group 22. Have been. The selection contact 23 corresponding to the terminal group 21 and the selection contact 24 corresponding to the terminal group 22 are linked with each other, operate based on information from the processing device 7, and select one loop coil. The selection circuit 2 is realized by combining a number of known multiplexers.

The transmission / reception switching circuit 3 alternately connects one loop coil selected by the selection circuit 2 to the transmission circuit 5 and the reception circuit 6, and the selection contacts 23 and 24 of the selection circuit 2 And 32 respectively.
Two output terminals of the transmission circuit 5 are connected to terminals 33 and 35, and two input terminals of the reception circuit 6 are terminals 34 and 36.
It is connected to the. Selection contacts 3 corresponding to the terminals 33 and 34
1 and the selection contacts 32 corresponding to the terminals 35 and 36 are interlocked with each other,
It operates based on a transmission / reception switching signal described later, and switches between transmission and reception. The transmission / reception switching circuit 3 is also realized by a known multiplexer.

The position indicator 4 is a stylus pen (hereinafter simply referred to as a pen) and has a tuning circuit 41 including a coil and a capacitor.

FIG. 2 shows a detailed structure of the pen 4. A pen 43 such as a ball-point pen and a core 43 are slid from the tip of a pen shaft 42 made of a non-metallic material such as a synthetic resin. A tuning circuit including a ferrite core 44 having a freely accommodating through hole, a coil spring 45, a switch 411, a coil 412 wound around the ferrite core 44, capacitors 413 and 414.
41 and 41 are integrally combined and built in, and a cap 46 is attached to the rear end.

The coil 412 and the capacitor 413 are connected in series with each other as shown in FIG. 3 so as to constitute a well-known resonance circuit. The phase of the current is set to a value that resonates (tunes) in phase. Also the capacitor
414 is connected in parallel to both ends of the capacitor 413 via a switch 411, and when the switch 411 is turned on,
The phase of the current in the above-described resonance circuit is delayed, and the phase of the received signal described later is delayed by a predetermined angle. The switch 411 holds the pen shaft 42 by hand or the like, and pushes the tip of the core body 43 into the pen shaft 42 by pressing the tip of the core 43 against an input surface (not shown) of the position detection unit 1. It is pressed via the coil spring 45 and is turned on.

Here, the above-described circuit comprising the coil 412 and the capacitor 413 is normally closed, and constitutes a first tuning circuit for instructing the tablet on the position to be measured. The switch 411, the coil 412, and the capacitors 413, 414 Is formed by an operation of the operator (here, the switch 411 is turned on by pushing the core 43 into the pen shaft 42), and the tuning frequency is different from that of the first tuning circuit and the A second tuning circuit for designating a position to be measured and notifying the operation is constituted (note that
The concept of “stationary” described above includes “the state where the operator does not operate”. ).

FIG. 3 shows the configuration of the entire device together with details of the tuning circuit 41, the transmission circuit 5 and the reception circuit 6. In FIG. 3, reference numeral 51 denotes a timing circuit, and 52 denotes a voltage-current conversion circuit. Also, 61 is an amplifier, 62 is a reception timing switching circuit, 63 is a bandpass filter (BPF), 64 is a detector, 65 and 66 are phase detectors (PSD), 67, 68 and 69 are low-pass filters ( LPF), and these constitute the receiving circuit 6.

The processing device 7 is composed of a well-known microprocessor or the like, controls the timing circuit 51, and
Control the switching of each loop coil, and a low-pass filter
The output values from 67 to 69 are converted from analog to digital (A / D), the arithmetic processing described later is executed to calculate the coordinate value of the position pointed by the pen 4, and the tuning circuit is determined to determine the operation state of the switch. Identify.

Here, the above-described position detection unit 1, selection circuit 2, connection switching circuit 3, and transmission circuit 5 (including the voltage-current conversion circuit 52) constitute a radio wave generating unit.
The selecting circuit 2, the connection switching circuit 3, and the receiving circuit 6 constitute a radio wave generating means, and the processing device 7 constitutes a coordinate calculating means and a tuning circuit determining means.

Next, the operation will be described. First, a description will be given of how the radio wave is transmitted and received between the position detecting unit 1 and the pen 4 and the signals obtained at this time with reference to FIG.

The timing circuit 51 has a predetermined frequency fo, for example, a rectangular wave signal A of 500 kHz, a signal A '(not shown) obtained by delaying the phase of the rectangular wave signal A by a predetermined angle, a predetermined frequency fk, for example, 15.6
A 25 kHz transmission / reception switching signal B and a reception timing signal C are generated. The rectangular wave signal A is sent to the phase detector 65, converted into a sine wave signal by a low-pass filter (not shown) and sent to the voltage-current conversion circuit 52, and the square wave signal A 'is sent to the phase detector 66. The transmission / reception switching signal B is transmitted to the transmission / reception switching circuit 3, and the reception timing signal C is transmitted to the reception timing switching circuit 62.

The voltage / current conversion circuit 52 converts the sine wave signal into a current signal proportional to only the voltage value and sends the current signal to the transmission / reception switching circuit 3. The transmission / reception switching circuit 3 receives the voltage / current conversion circuit 52 based on the transmission / reception switching signal B. The signal output from the transmission / reception switching circuit 3 to the selection circuit 2 is switched to the time T (= 1 / 2fk), in this case, 500 k every 32 μsec.
It becomes a current signal D that outputs or does not output a signal of Hz.

The current signal D is sent to one loop coil 11-i (i = 1, 2,..., 48) of the position detection unit 1 via the selection circuit 2, and at this time, the loop coil 11-i The current signal D
Generates radio waves based on

At this time, if the pen 4 is held substantially upright in the vicinity of the loop coil 11-i of the position detection unit 1, that is, in the use state, the radio wave excites the coil 412 of the pen 4 and the tuning circuit 41 thereof. An induced voltage E synchronized with the current signal D is generated.

Thereafter, the current signal D enters a period in which there is no signal, that is, a reception period, and the loop coil 11-i is switched to the reception circuit 6.
When switched to the side, the radio wave from the loop coil 11-i disappears immediately, but the induced voltage E gradually attenuates in accordance with the loss in the tuning circuit 41.

On the other hand, the current flowing through the tuning circuit 41 based on the induced voltage E causes the coil 412 to emit radio waves. Since the radio wave excites the loop coil 11-i connected to the receiving circuit 6 in reverse, an induced voltage due to the radio wave from the coil 412 is generated in the loop coil 11-i. The induced voltage is sent from the transmission / reception switching circuit 3 to the amplifier 61 and amplified to the reception signal F only during the reception period.
Sent to

A reception timing signal C, which is substantially an inverted signal of the transmission / reception switching signal B, is input to the reception timing switching circuit 62. When the signal C is at a high (H) level, the reception signal F
And outputs nothing during the low (L) level period, so that its output has a signal G (substantially the same as the received signal F).
And the signal G is sent to the bandpass filter 63.

The bandpass filter 63 is a filter having a pass band centered on the frequency fo, and a signal H having an amplitude h corresponding to the energy of the frequency fo component in the signal G (strictly, several signals G (In the state of being input to the filter 63 and converged) to the detector 64 and the phase detectors 65 and 66.

The signal H input to the detector 64 is detected and rectified,
Low-pass filter with sufficiently low cutoff frequency after signal I
At 67, the signal is converted into a DC signal J having a voltage value Vx corresponding to approximately の of the amplitude h, and sent to the processing device 7.

The voltage value Vx of the signal J is determined by the pen 4 and the loop coil 11-i.
Indicates a value proportional to the distance between the loop coil 11-i
Is changed when is switched, the voltage value Vx obtained for each loop coil is converted into a digital value, and the arithmetic processing described later is performed on the voltage value Vx, whereby the coordinate value of the position specified by the pen 4 is calculated.

On the other hand, the rectangular wave signal A is input to the phase detector 65 as a detection signal. At this time, the switch 411 is off, and the phase of the signal H substantially matches the phase of the rectangular wave signal A. In this case, a signal (in substantially the same as the signal I) obtained by inverting the signal H to the positive side is output. This signal is converted into a DC signal (substantially the same as the signal J) having a voltage value corresponding to approximately 1/2 of the amplitude h by the low-pass filter 68 as described above, and sent to the processing device 7.

Further, although the rectangular wave signal A 'is input to the phase detector 66 as a detection signal, as described above, the switch 411 is turned off, and the phase of the signal H is shifted from the phase of the rectangular wave signal A'. If it advances by a predetermined angle, a signal having components on the positive side and the negative side is output. This signal is converted to a DC signal by the same low-pass filter 69 as described above and sent to the processing device 7. However, since the output signal of the phase detector 66 has components on the positive side and the negative side, the low-pass filter 69 The output voltage value is considerably smaller than the output voltage value of the low-pass filter 68.

Here, when the switch 411 of the pen 4 is turned on, the phase of the current flowing through the tuning circuit 41 is delayed with respect to the induced voltage E,
The phase of the received signal F is also delayed by a predetermined angle, that is, almost coincides with the phase of the rectangular wave signal A '. Accordingly, the output H of the bandpass filter 63 at this time is converted into a signal having components on the positive side and the negative side by the phase detector 65, and the output of the low-pass filter 68 is the low-pass filter 69 when the switch 411 is off. Is almost the same as the output of the low pass filter 69, but the output of the low-pass filter 69 has a predetermined voltage value corresponding to almost half the amplitude h, as described above. It becomes a DC signal having.

Thus, when the switch 411 is off, the low-pass filter 6
Since a predetermined voltage value is obtained at the output of the switch 8 and a predetermined voltage value is obtained at the output of the low-pass filter 69 when the switch 411 is turned on, the low-pass filter 68 and the
By monitoring the output value of 69, it is possible to detect whether the switch 411 is off or on.

The information indicating the on (or off) state of the switch 411 identified here is used as information for specifying a value to be actually input among the coordinate values of the position specified by the pen 4.

Next, the position detection and the state of the pen 4, in this case, the on / off state of the switch 411, in the apparatus of the present invention will be described with reference to FIGS.

First, when the power of the entire device is turned on and the measurement is started, the processing device 7 sets the loop coil 11-1 of the position detection unit 1 to a position.
11-48, information for selecting the first loop coil 11-1 is sent to the selection circuit 2, and the loop coil 11-1 is connected to the transmission / reception switching circuit 3. The transmission / reception switching circuit 3 alternately controls the switching of the loop coil 11-1 to the transmission circuit 5 and the reception circuit 6 based on the transmission / reception switching signal B described above.

At this time, the transmission circuit 5 operates in the transmission period of 32 μsec.
As shown in FIG. 5A, 16 sinusoidal current signals of 500 kHz are sent to the loop coil 11-1. The switching between transmission and reception is repeated seven times for one loop coil, here 11-1, as shown in FIG. 5 (b). The seven transmission and reception repetition periods correspond to one loop coil selection period (448 μsec).

The output of the reception timing switching circuit 62 of the reception circuit 6 includes:
An induction voltage is obtained every seven reception periods for one loop coil. This induction voltage is averaged by the bandpass filter 63 as described above, and the detector 64, the phase detectors 65 and 66, and the low The signal is sent to the processing device 7 through the pass filters 67 to 69.
At this time, the output value of the low-pass filter 67 is subjected to A / D conversion, and a detection voltage proportional to the distance between the pen 4 and the loop coil 11-1,
For example, it is temporarily stored as Vx1 (the output values of the low-pass filters 68 and 69 are actually A / D converted, but the value at this time is not used).

Next, the processing device 7 sends information for selecting the loop coil 11-2 to the selection circuit 2, connects the loop coil 11-2 to the transmission / reception switching circuit 3, and is proportional to the distance between the pen 4 and the loop coil 11-2. The detected detection voltage Vx2 is obtained and stored. Thereafter, the loop coils 11-3 to 11-48 are similarly sequentially transmitted and received by the transmission / reception switching circuit 3.
And detection voltages Vx1 to Vx48 in proportion to the distance between each loop coil and the pen 4 as shown in FIG. 5 (c). Is stored in a simple expression.).

The actual detected voltage is obtained only in the several loop coils before and after the position (xp) where the pen 4 is placed as a center, as shown in FIG.

By the way, there is a variation (for example, 30 ± 5Ω) in the on-resistance of each of the loop coils of the selection circuit 2 composed of the multiplexer. As a result, a difference occurs in the current value flowing through each loop coil. The strength of the radio wave generated from the loop coil is proportional to the value of the current flowing through the loop coil, and the strength of the radio wave is the voltage value of the induced voltage generated in the tuning circuit 41, and finally generated in the loop coil during the reception period. As described above, if there is a difference in the current value flowing through each loop coil as described above, the detected induced voltage is accurately proportional to the distance between the pen 4 and each loop coil. No longer.

In the present invention, by using the voltage-current conversion circuit 52,
The value of the current flowing through each loop coil is kept constant regardless of the variation of the on-resistance in the selection circuit 2, and the induced voltage detected depends only on the distance between the pen 4 and each loop coil, and is accurately proportional to this. As a result, the position detection accuracy was improved.

FIG. 7 shows a loop coil, for example, 11-1, 11-2, 11-3, 11 when the pen 4 is moved in a direction orthogonal to the position detection direction.
4 shows changes in induced voltages VR1, VR2, VR3, and VR4 generated in FIG. 4. FIG. 7 (a) shows the value when the loop coil is driven by voltage, and FIG. 7 (b) shows the voltage / current. The values when current driving is performed using the conversion circuit are shown.

In FIG. 7A, the deviation of the curve of each induced voltage in the voltage direction indicates that there is a difference in the current value flowing through each loop coil, and in FIG. The fact that the voltage curve is not shifted in the voltage direction indicates that there is no difference between the current values flowing through the respective loop coils.

When the voltage value of the stored detection voltage is equal to or higher than a predetermined detection level, the processing device 7 calculates a coordinate value indicating the designated position of the pen 4 from these voltage values as described later.

Next, the processing device 7 controls the loop coils 11-1 to 11-48.
Among them, the loop coil for which the maximum detection voltage is obtained is detected, information for selecting the coil is transmitted to the selection circuit 2, and the transmission and reception of the radio wave are repeated a plurality of times, for example, seven times. A / D conversion of the output value obtained from and 69,
As described above, which of these values is equal to or greater than the predetermined value is detected, and the on / off state of the switch 411 is identified.

The on / off identification result of the switch 411 is transferred to a host device (not shown) together with the coordinate value indicating the designated position of the pen 4 described above.

When the first position detection and state identification are completed in this way, the processing device 7 performs the second and subsequent position detection as shown in FIG.
Out of the loop coil from which the maximum detection voltage is obtained, a fixed number of information before and after the center, for example, information for selecting only 10 loop coils is sent to the selection circuit 2, and the output value is obtained in the same manner as described above. Position detection and switch for pen 4
The on / off state of 411 is identified, the obtained coordinate values and identification results are transferred and updated, and thereafter, these are repeated.

Therefore, when the pen 4 is operated on the position detection unit 1, all coordinate values of the position specified by the pen 4 during that time are transferred to the host device, and at this time, when the switch 411 is turned on,
The identification information in the ON state is transferred to the host device, and the host device can recognize the coordinate value at this time as a coordinate value to be input.

In FIG. 8, the level check is to check whether the maximum value of the detection voltage has reached the detection level and to determine which loop coil has the maximum value of the detection voltage, and determine the detection level. If it has not reached, the subsequent coordinate calculation and the like are stopped, and the center of the loop coil to be selected in the next position detection operation and state identification operation is set.

As one method of calculating the coordinate value xp, there is a method of approximating the waveform near the maximum value of the detection voltages Vx1 to Vx48 by an appropriate function, and obtaining the coordinates of the maximum value of the function.

For example, in FIG. 5 (c), the maximum detection voltage Vx3
, And the detection voltages Vx2 and Vx4 on both sides thereof can be calculated as follows by approximation by a quadratic function (however, the coordinate values of the center positions of the loop coils 11-1 to 11-48 are x1 to
x48, and the interval is Δx. ). First, from the voltages and coordinate values, Vx2 = a (x2-xp) ² + b (1) Vx3 = a (x3-xp) ² + b (2) Vx4 = a (x4-xp) ² + b ... (3) Here, a and b are constants (a <0). X3−x2 = Δx (4) x4−x2 = 2Δx (5) By substituting equations (4) and (5) into equations (2) and (3), xp = X2 + Δx / 2 ｛(3Vx2−4Vx3 + Vx4) / (Vx2−2Vx3 + V
x4)｝ ... (6)

Therefore, the maximum value of the detection voltage obtained at the time of the level check and the detection voltages before and after that are extracted from each of the detection voltages Vx1 to Vx48, and these and the one of the loop coil from which the maximum value of the detection voltage is obtained are extracted. The coordinate value xp of the designated position of the pen 4 can be calculated by performing an operation corresponding to the above-described equation (6) from the coordinate value (known) of the previous loop coil.

FIG. 9 shows a second embodiment of the present invention, in which an example in which position detection in the X and Y directions is performed is shown. That is, in the figure, reference numeral 1a denotes a position detection unit in the X direction and the Y direction.
In this embodiment, two sets of position detectors 1 are superposed such that their loop coils are orthogonal to each other. 2a and 2b are selection circuits in the X and Y directions, 3a and 3b
Is a transmission / reception switching circuit in the X and Y directions, 52a and 52b are voltage-current conversion circuits in the X and Y directions, and 61a and 61b are amplifiers in the X and Y directions. , Transmission / reception switching circuit 3, voltage / current conversion circuit 5,
2. It has the same configuration as the amplifier 61.

Reference numeral 53 denotes an XY switching circuit, which applies a sine wave signal input from the timing circuit 51 via a low-pass filter (not shown) to one of the voltage-current conversion circuits 52a and 52b and selects a direction for position detection. It is for doing. Also, 62 '
Is a reception timing switching circuit for selecting the reception timing together with the direction in which the reception signal from the amplifier 61a or the amplifier 61b is detected, and adding it to the bandpass filter 63. Reference numeral 7a denotes a processing device, which controls the XY switching circuit 53 and the reception timing switching circuit 62 ', except that the X and Y directions are alternately detected.
This is the same as the processing device 7. FIG. 10 shows timings of the second and subsequent position detection operations and state identification operations in the processing device 7a.

As described above, according to the present embodiment, it is possible to easily detect the positions (coordinates) of the pen 4 in the two directions of the X direction and the Y direction. Other configurations and operations are the same as those of the first embodiment.

In the first or second embodiment, the position detector 1
Alternatively, by attaching a microphone or the like to 1a and providing the processing device 7 or 7a with a voice recognition function, various instructions can be performed by voice. In the second embodiment, the processing device 7a Alternatively, a higher-level device having a character recognition function can be used as a tablet for inputting handwritten characters.

Further, the number of loop coils and the arrangement thereof in the embodiment are merely examples, and it is needless to say that the present invention is not limited to this.

(Effects of the Invention) As described above, according to the present invention, the first and second tunings are performed on the position indicator having the first and second tuning circuits having different tuning frequencies from the radio wave generating means of the tablet. Generates radio waves with a constant magnetic field strength that the circuit can tune,
The radio wave of the tablet detected by the first tuning circuit, which is normally closed, of the first and second tuning circuits, or the radio wave caused by the tuning reflected from the second tuning circuit constituted by the operation of the operator. Means, and further calculates the coordinate value of the position indicated by the position indicator on the tablet regardless of whether or not the operation has been performed by the coordinate calculation means with a finer accuracy than the arrangement interval of the plurality of loop coils, Further, the tuning circuit discriminating means detects whether the radio wave reflected from the position indicator to the tablet is the radio wave reflected from the first or second tuning circuit, and determines the operation state of the position indicator. Since detection is performed, the position indicator only needs to be provided with a passive element such as a coil or a capacitor for forming a tuning circuit, and no code is required. It does not hinder or break due to fatigue, and does not require heavy parts such as batteries and magnets. In addition to the fact that the performance is extremely improved, an induced voltage that always depends only on the position indicated by the position indicator is obtained, and the above-described operation is performed on the coordinate values on the tablet with a finer accuracy than the arrangement interval of each loop coil, that is, with higher accuracy. Can be detected regardless of whether
Further, there is an advantage that the operation of the operator on the position indicator can be detected in addition to the detection of the coordinate value depending on which tuning circuit reflects the radio wave.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a position detecting device of the present invention, FIG. 2 is a cross-sectional view of a stylus pen, and FIG. 3 is a device together with details of a tuning circuit, a transmitting circuit and a receiving circuit of the stylus pen. FIG. 4 is a signal waveform diagram of each part in FIG. 3, and FIGS. 5 (a), (b) and (c) are timing diagrams showing a basic position detecting operation in the first embodiment. ,
FIG. 6 is a diagram showing a detection voltage obtained from each loop coil at the time of the first position detection operation. FIGS. 7 (a) and 7 (b) show the pen 4 moved in a direction orthogonal to the position detection direction. FIG. 8 is a diagram showing a change in induced voltage generated in a loop coil at the time,
FIG. 9 is a timing chart showing the position detection operation and the state identification operation after the second time, FIG. 9 is a diagram similar to FIG. 3 showing a second embodiment of the present invention, and FIG. 10 is a second embodiment. 8th in
It is a figure similar to a figure. 1. Position detector, 11-1 to 11-48 ... Loop coil, 2 ....
Selection circuit, 3 ... transmission / reception switching circuit, 4 ... stylus pen,
5: transmission circuit, 6: reception circuit, 7: processing device, 41: tuning circuit.

Continued on the front page (72) Inventor Toshihide Senzu 5-23-4 Sakurada, Washinomiya-cho, Kita-Katsushika-gun, Saitama

Claims (3)

(57) [Claims] 1. A position detecting device for transmitting and receiving signals between a position indicator and a tablet, and detecting a coordinate value on the tablet indicated by the position indicator, wherein the position detecting device is constantly closed and connected to the tablet. On the other hand, a first tuning circuit for designating the position to be measured, and a tuning frequency different from that of the first tuning circuit, which is constituted by an operation of an operator, indicating the position to be measured to the tablet and notifying the operation. A position indicator having a second tuning circuit for performing the operation, and a radio wave generating means configured of a plurality of loop coils and generating a radio wave of a constant magnetic field strength that can be tuned by the first and second tuning circuits, and A tablet having radio wave detecting means for detecting a radio wave caused by the tuning reflected from the first or second tuning circuit; and a plurality of loop coils constituting the radio wave detecting means, A coordinate value of a position indicated by the position indicator on the tablet is obtained from a plurality of induced voltages induced by the injection, regardless of whether the operation is performed with a finer accuracy than an arrangement interval of the plurality of loop coils. From the induced voltage induced by the reflection on the loop coil constituting the radio wave detecting means, the radio wave reflected from the position indicator to the tablet is output from either the first or second tuning circuit. A position detecting device comprising: a tuning circuit determining unit configured to detect whether or not the reflected radio wave is detected and to detect an operation state of the position indicator. 2. The position detecting device according to claim 1, wherein the radio wave generating means and the radio wave detecting means are operated alternately. 3. The position detecting device according to claim 2, wherein the loop coil constituting the electric wave generating means and the loop coil constituting the electric wave detecting means are used in combination.