JPH07109577B2 - Position detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a position detection device capable of simultaneously using a plurality of cordless position pointing devices.

(Prior Art) As a conventional position detecting device, a pulse current is applied to a drive coil provided at one end of a magnetostrictive transmission medium or at the tip of a position indicator to generate a magnetostrictive vibration wave in the magnetostrictive transmission medium. , The time until it detects the induced voltage based on the magnetostrictive vibration wave in the detection coil provided at the tip of the position indicator or one end of the magnetostrictive transmission medium is measured by a processing device, etc., and the designated position of the position indicator is calculated from this. There was something I did. Further, as another conventional position detection device, a plurality of drive lines and a detection line are arranged orthogonal to each other, and the induced voltage is detected by sequentially passing a current through the drive lines and sequentially selecting the detection lines, There has been a device in which a position designated by a position indicator having a magnetic material such as ferrite is detected from the position of a detection line in which 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 in order to send and receive timing signals and the like. The handling was severely limited and the position indicator had to be held perpendicular to the magnetostrictive transmission medium and used in close proximity. Also, in the latter device, the position indicator can be made cordless, but the resolution of the coordinate position is determined by the line spacing, and if the line spacing is reduced in order to increase the resolution, the SN ratio and stability deteriorate, so It was difficult to increase the resolution, and it was difficult to detect the position directly above the intersection of the drive line and the detection line, and the position indicator had to be brought very close to the line. Further, in any of the above-mentioned devices, there is a problem that it is not possible to detect the designated position by using two or more position indicators at the same time.

The present invention has improved the above-mentioned conventional problems. The position indicator is not connected to anywhere and the operability is good, and a plurality of position indicators can be used simultaneously, and highly accurate position detection is possible. It is an object of the present invention to provide a device capable of

(Means for Solving Problems) In the present invention, in order to achieve the above object, 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 plurality of position indicators having a plurality of tuning circuits each having a predetermined frequency and one of n (= 2, 3, ...) Harmonics of the predetermined frequency as a tuning frequency. When,
A radio wave generating unit configured to generate a radio wave having the predetermined frequency and a radio wave having substantially the same frequency as the predetermined frequency or the frequency of the nth harmonic thereof reflected from the plurality of tuning circuits are formed of a plurality of loop coils. A tablet having a radio wave detecting means for detecting each of a predetermined frequency and its nth harmonic, and the predetermined frequency and its nth harmonic induced by the reflection in a plurality of loop coils constituting the radio wave detecting means. Position detection including coordinate calculation means for obtaining coordinate values of pointing positions of the plurality of position pointing devices on the tablet with precision smaller than the arrangement intervals of the plurality of loop coils from a plurality of induced voltages for each frequency of the wave. Suggest a device.

(Operation) According to the present invention, when a radio wave having a predetermined frequency is generated by the radio wave generating means composed of a plurality of loop coils, the radio wave is transmitted to each tuning circuit of a plurality of position pointing devices for performing position designation on the tablet. Although tuned, that is, received, a plurality of tuning circuits that have received the radio waves emit, or reflect, radio waves having substantially the same frequency as the predetermined frequency or the frequency of the nth harmonic thereof. The reflected radio wave having the same frequency as the predetermined frequency or the frequency of the nth harmonic thereof is detected by the radio wave detecting means composed of a plurality of loop coils of the tablet for each of the predetermined frequency and the frequency of the nth harmonic thereof. The coordinate values of the detected position of the plurality of position indicators on the tablet are calculated by the coordinate calculation means with a finer precision than the arrangement intervals of the plurality of loop coils.

(Embodiment) FIG. 1 shows a first embodiment of the position detecting device of the present invention, in which 1 is a position detecting unit, 2 is a selection circuit, 3 is a connection switching circuit, and 4 and 5 are positions. An indicator, 6 is a transmitting circuit, 7 is a receiving circuit, and 8 is a processing device.

In the position detecting unit 1, a plurality of, for example, 48 loop coils 11-1, 11-2, ... 11-48 having conductors parallel to each other are arranged in the direction of arrow a in the figure (hereinafter referred to as a position detecting direction). ) Are installed side by side. Also, each loop coil 11-1 to 11-
The 48's are arranged parallel to each other and overlapping.
Although each loop coil 11-1 to 11-48 has one turn here, it may have a plurality of turns if necessary.

As the position detector 1, use is made of a plurality of loop coils formed by connecting a large number of parallel conductors formed by, for example, etching a known printed circuit board with jumper wires or the like. You can

The selection circuit 2 includes a plurality of loop coils 11-1 to 11-48.
One of the loop coils is sequentially selected, 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, respectively. ing. The selection contact 23 corresponding to the terminal group 21 and the selection contact 24 corresponding to the terminal group 22 are interlocked with each other and operate based on the information from the processing device 8 to select one loop coil.

The selection circuit 2 can be realized by combining a number of well-known multiplexers.

The connection switching circuit 3 alternately connects one loop coil selected by the selection circuit 2 to the transmission circuit 6 and the reception circuit 7. The selection contacts 23 and 24 of the selection circuit 2 are the selection contacts 31. And 32 respectively. Also, the two output terminals of the transmission circuit 6 are connected to the terminals 33 and 35, and the two input terminals of the reception circuit 7 are the terminals 3 and 35.
It is connected to 4,36. The selection contact 31 corresponding to the terminals 33 and 34 and the selection contact 32 corresponding to the terminals 35 and 36 are interlocked with each other and operate based on a transmission / reception switching signal described later to switch between transmission and reception.

The connection switching circuit 3 is also realized by a known multiplexer.

The position indicator (hereinafter referred to as an input pen) 4 and the position indicator (hereinafter referred to as a cursor) 5 have tuning circuits 41 and 51 including a coil and a capacitor, respectively.

FIG. 2 shows a detailed structure of the input pen 4. Inside the pen shaft 42 made of a non-metallic material such as synthetic resin, a core body 43 such as a ballpoint pen and the core body 43 are slid from the tip side thereof. A ferrite core 44 having a through hole that can be accommodated movably, a coil spring 45, a switch 411, a coil 412 wound around the ferrite core 44, and a tuning circuit 41 including capacitors 413 and 414 are integrally formed. It is assembled and incorporated, and a cap 46 is attached to the rear end thereof.

The coil 412 and the capacitor 413 are connected in parallel to each other as shown in FIG. 4 so as to form a well-known parallel resonance circuit, and the numerical values of the coil 412 and the capacitor 413 are the frequency of an AC signal described later. At f0, the voltage and current phases are set to a value that causes resonance (tuning) in the same phase. Further, the capacitor 414 is a coil via the switch 411.
It is connected to both ends of 412 and the capacitor 413, and when the switch 411 is turned on, it acts to delay the phase of the current in the parallel resonant circuit described above by a predetermined angle, for example, 90 °. The switch 411 presses the tip of the core body 43 against the input surface (not shown) of the position detection unit 1 to push the core body 43 into the pen shaft 42, and the coil spring 45 is pushed by the rear end of the core body 43. It is pressed through and is turned on.

FIG. 3 shows a detailed structure of the cursor 5, which is a transparent columnar body 53 made of plastic or the like having a bottom surface provided with an index “+” at one end of a housing 52 made of a non-metallic material such as synthetic resin. Is attached, and a switch 511 is provided on the side surface near the center. A coil 512 is provided around the cylindrical body 53 so as to surround the cylindrical body 53, and capacitors 513 and 514 are further incorporated therein. Although the coil 512 is shown as a two-turn coil in the drawing,
Actually, it consists of several hundred turns of coil. The tuning circuit 51 is composed of the switch 511, the coil 512, and the capacitors 513 and 514.

The coil 512 and the capacitor 513 are connected in parallel to each other as shown in FIG. 4 so as to form a well-known parallel resonance circuit. The numerical values of the coil 512 and the capacitor 513 are the frequency f0 of the AC signal. At a frequency of n (= 2, 3, ...) Multiples, for example, triple, the voltage and the current are set to a value that causes resonance (tuning) in phase. The capacitor 514 is connected to both ends of the coil 512 and the capacitor 513 via the switch 511, and when the switch 511 is turned on, the capacitor 514 acts to delay the phase of the current in the parallel resonant circuit by a predetermined angle, for example, 90 °. .

FIG. 4 shows tuning circuits 41, 51, transmitting circuit 6 and receiving circuit 7.
2 shows the configuration of the entire apparatus together with the details of FIG. In the figure, 601 is a waveform shaping circuit, 602 is a multiplier, 603 and 604 are phase shifters, and 605 is a drive circuit, which constitute the transmission circuit 6. Further, 701 is an amplifier, and 702 and 703 are bandpass filters (BP
F), 704,705,706,707 are phase detectors (PSD), 708,709,7
Reference numeral 10,711 is a low-pass filter (LPF), and 712,713,714,715 are analog-digital converters (AD converters), which form the receiving circuit 7.

The processing device 8 is composed of a well-known microprocessor or the like, generates an AC signal and a transmission / reception switching signal, and
The switching of each loop coil is controlled based on the output of the receiving circuit 7, and the coordinate values of the plurality of tuning circuits, that is, the coordinate values of the indicated positions of the plurality of position indicators are calculated.

Here, the position detection unit 1, the selection circuit 2, the connection switching circuit 3 and the transmission circuit 6 described above constitute a radio wave generating means, and the position detection unit 1, the selection circuit 2, the connection switching circuit 3 and the reception circuit 7 are also provided.
Constitutes the radio wave detecting means, and the processing device 8 constitutes the coordinate calculating means.

Next, the operation will be described. First, the manner in which radio waves are transmitted and received between the position detector 1 and the input pen 4 and the cursor 5 and the signals obtained at this time will be described with reference to FIG.

The processing device 8 generates an AC signal having a frequency f0, for example, 500 kHz, for example, a rectangular wave signal A, and a transmission / reception switching signal B having a frequency of 15.625 kHz, based on a clock from an oscillator (not shown).

The rectangular wave signal A is sent to the waveform shaping circuit 601, the waveform is shaped, and further sent to the multiplier 602 and the phase shifter 603. The frequency multiplier 602 multiplies the frequency of the rectangular wave signal A by n, which is three times 3f0 in this case, to generate a rectangular wave signal C, and sends this to the phase shifter 604.

The phase shifter 602 keeps the phase of the rectangular wave signal A (0
Signal) and a signal delayed by 90 ° (not shown)
And sends them to the phase detectors 704 and 705, respectively, and the phase shifter 603 outputs a signal in which the phase of the rectangular wave signal C in the previous period is left unchanged (0 °) and a signal delayed by 90 ° (not shown). ) And create phase detectors 706 and 7
Send to 07 respectively.

On the other hand, the rectangular wave signal A is converted into a balanced signal by the drive circuit 605 and sent to the connection switching circuit 3, but since the connection switching circuit 3 is switch-controlled by the signal B,
The signal output from the connection switching circuit 3 to the selection circuit 2 is 32
It becomes a signal D that outputs or does not output a pulse signal of 500 kHz every μsec.

The signal D is sent to one loop coil, for example, 11-i of the position detector 1 through the selection circuit 2, and at this time, the loop coil 11-i generates a radio wave based on the signal D.

At this time, when the input pen 4 is held in a substantially upright state near the loop coil 11-i of the position detecting section 1, the radio wave excites the coil 412 of the input pen 4 and the tuning circuit 41 receives the signal. An induced voltage E synchronized with D is generated.

By the way, since the radio wave is transmitted based on the rectangular wave signal A, the fundamental frequency of the rectangular wave signal A, that is, f0
In addition to the component of, the harmonic component having the frequency of 2 times, 3 times, ... Therefore, the radio wave generated from the loop coil 11-i based on the signal D is the coil 512 of the cursor 5 placed at another position on the position detection unit 1.
To generate an induced voltage F having a frequency three times that of the signal D in the tuning circuit 51.

After that, in the signal D, when the loop coil 11-i is switched to the receiving circuit 7 side when the signal-less period, that is, the reception period is entered, the radio wave from the loop coil 11-i immediately disappears, but the input pen 4 Since there is no circuit change in the tuning circuit 41 of and the tuning circuit 51 of the cursor 5,
The induced voltages E and F gradually attenuate.

On the other hand, the currents flowing through the tuning circuits 41 and 51 based on the induced voltages E and F cause the coils 412 and 512 to emit radio waves, respectively. Since the radio wave excites the loop coil 11-i connected to the receiving circuit 7 in the opposite direction, the induction voltage of the radio wave from the coil 412 and the induction voltage of the radio wave from the coil 512 are combined in the loop coil 11-i. The induced voltage G generated is generated.

Since the connection switching circuit 3 is switched by the transmission / reception switching signal B, the loop coil 11 is operated only during the transmission suspension period.
Take in induced voltage G from -i. The induced voltage G is amplified by the amplifier 701, and the bandpass filters 702 and 70 are further added.
Dispatched to 3.

Since the band-pass filter 702 is a filter having a pass band centered on the frequency f0, only the induced voltage component due to the tuning circuit 41 in the signal G appears in the output H of the band-pass filter 703. Since the filter has a pass band centered on the frequency of C, that is, 3f0, only the induced voltage component in the signal G due to the tuning circuit 51 appears in the output I.

The signal H is input to the phase detectors 704 and 705, respectively, and the signal I is input to the phase detectors 706 and 707, respectively.

The rectangular wave signal A is input to the phase detector 704 as a detection signal. At this time, the phase of the signal H is the rectangular wave signal A.
If it matches the phase of, the signal J which is just the signal H inverted to the positive side is output. The signal J is converted into a flat signal K having a voltage VK by a low pass filter 708 having a sufficiently low cutoff frequency.

Further, a signal A ′ (not shown) obtained by delaying the phase of the rectangular wave signal A by 90 ° is input to the phase detector 705 as a detection signal, and at this time, the phase of the signal H is the rectangular wave signal A ′. If they match the phase, a signal obtained by inverting the signal H to the plus side is output as in the above. The signal is a low pass filter similar to the above
Converted to flat signal at 709.

On the other hand, the rectangular wave signal C is input to the phase detector 706 as a detection signal. At this time, if the phase of the signal I matches the phase of the rectangular wave signal C, the signal I is just set to the plus side. The inverted signal L is output. The signal L is converted into a flat signal M having a voltage VM by a low-pass filter 710 having a sufficiently low cutoff frequency.

A signal C ′ (not shown) obtained by delaying the phase of the rectangular wave signal C by 90 ° is input to the phase detector 705 as a detection signal. At this time, the phase of the signal I is the rectangular wave signal C ′. If they match the phase, a signal obtained by inverting the signal I to the plus side is output as in the above. The signal is a low pass filter similar to the above
Converted to flat signal at 711.

Here, in the input pen 4 and the cursor 5, when the switches 411 and 511 are off, as described above, the phases of the voltage and the current at the resonance frequencies of the tuning circuits 41 and 51 match, and Signals H and I
And the rectangular wave signals A and C also have the same phase. Therefore, at this time, a voltage appears only at the outputs of the low-pass filters 708 and 710, and no voltage appears at the outputs of the low-pass filters 709 and 711.

Further, in the input pen 4, when the switch 411 is turned on, the phase of the current at the resonance frequency of the tuning circuit 41 is delayed by 90 ° with respect to the phase of the voltage as described above, and the reception signal H The phase also lags the phase of the rectangular wave signal A by 90 °. Therefore, at this time, a voltage appears only in the output of the low-pass filter 709 (note that, if the phase delay at this time is less than 90 °, the phase-lag appears in both the outputs of the low-pass filters 708 and 709. The voltage value of the value corresponding to the quantity will appear.)

Similarly, when the switch 511 is turned on at the cursor 5, the phase of the current at the resonance frequency of the tuning circuit 51 is delayed by 90 ° with respect to the phase of the voltage as described above, and the phase of the received signal I Also lags the phase of the rectangular wave signal C by 90 °. Therefore, at this time, the voltage appears only at the output of the low-pass filter 711 (Note that if the phase delay at this time is less than 90 °, the phase delay is output to both the outputs of the low-pass filters 710 and 711. The voltage value of the value corresponding to the quantity will appear.)

The outputs of the low-pass filters 708 to 711 are converted into digital values by the AD converters 712 to 715, respectively, and sent to the processing device 8. The processing unit 8 performs arithmetic processing shown in the following equations (1) and (2) on the output values of the AD converters 712 and 713 and the output values of the AD converters 714 and 715.

VR = (VP ² + VQ ² ) ^1/2 (1) V _θ = tan ^-1 (VQ / VP) (2) where VP is the output value of the AD converter 712 (or 714),
VQ is the output value of the AD converter 713 (or 715). The voltage VR shows a value proportional to the distance between the input pen 4 (or the cursor 5) and the loop coil 11-i, and the voltage V _θ is the tuning circuit 41 of the input pen 4 (or the tuning circuit 5 of the cursor 5).
The value is proportional to the phase difference between voltage and current in 1).

The value of the voltage VR changes when the loop coil 11-i that transmits and receives radio waves to and from the input pen 4 (or the cursor 5) is switched, and the position of the input pen 4 (or the cursor 5) is changed as will be described later. To be detected.

Since the value of the voltage V _θ changes only by turning on / off the switch 411 (or 511), by comparing the voltage V _θ with a predetermined threshold voltage, the switch 411 (or 51)
On / off of 1) is identified.

Next, with reference to FIGS. 6 to 8, the manner of position detection in the apparatus of the present invention will be described.

First, when the power of the entire apparatus is turned on and the measurement is started, the processing apparatus 8 causes the loop coil 11-1 to
Information for selecting the first loop coil 11-1 out of 11-48 is sent to the selection circuit 2 and the loop coil 11-1 is connected to the connection switching circuit 3. The connection switching circuit 3 connects the loop coil 11-1 to the transmission circuit 6 based on the transmission / reception switching signal B described above.
And the receiving circuit 7 is alternately switched.

At this time, the transmission circuit 6 displays 16 pulse signals of 500 kHz as shown in FIG. 6 (a) during the transmission period of 32 μsec (only four of them are shown in FIG. 5 for the convenience of the drawing). Is 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. 6 (b). The repeating period of seven times of transmission and reception corresponds to the selection period (448 μsec) of one loop coil.

At the outputs of the phase detectors 704 to 707 of the receiving circuit 7, an induced voltage is obtained for each loop coil every seven reception periods. This induced voltage is, as described above, low-pass filter 708.
˜711, averaged, converted into digital values by AD converters 712 to 715, and sent to the processing device 8. At this time, the output values of the AD converters 712 and 713 are converted into a value proportional to the distance between the input pen 4 and the loop coil 11-1, for example, VR1, by the arithmetic processing of the equation (1), and temporarily stored.

At this time, at the same time, the output values of the AD converters 714 and 715 are converted into a voltage proportional to the distance between the cursor 5 and the loop coil 11-1 by the arithmetic processing of the equation (1). I don't remember.

Next, the processing device 8 sends information for selecting the loop coil 11-2 to the selection circuit 2, connects the loop coil 11-2 to the connection switching circuit 3, and determines the distance between the input pen 4 and the loop coil 11-2. A proportional detection voltage VR2 is obtained and stored, and thereafter,
Similarly, the loop coils 11-3 to 11-48 are sequentially connected to the connection switching circuit 3, and the detection voltages VR1 to VR4 proportional to the distance from the input pen 4 for each loop coil as shown in FIG. 6 (c).
8 (however, in FIG. 6 (c), only a part thereof is shown by analog expression) is stored.

As shown in FIG. 7, the actual detection voltage is obtained only in several loop coils before and after the position (xp) where the input pen 4 is placed.

When the voltage value of the stored detection voltage is equal to or higher than a certain detection level, the processing device 8 calculates a coordinate value representing the position of the input pen 4 from these voltage values, as will be described later, and stores this coordinate value not shown. Forward to department.

Next, the processing unit 8 determines the distance between the output value of the AD converters 714, 715 and the cursor 5 for each loop coil obtained by performing the arithmetic processing of the equation (1) when the selection circuit 2 is switched in the same manner as described above. The proportional detected voltage is temporarily stored, the coordinate value representing the position of the cursor 5 is calculated, and this is transferred to the storage unit.

When the first position detection is completed in this way, the processor 8 detects the maximum position among the loop coils 11-1 to 11-48 as the second and subsequent position detections, as shown in FIG. With the loop coil from which the voltage is obtained as the center, a constant value before and after the loop coil, 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 to obtain the input pen 4 and the cursor. The position detection for No. 5 is performed, the obtained coordinate value is transferred to the storage unit, and the value is updated.

In FIG. 8, the level check means whether or not the maximum value of the detection voltage has reached the detection level, and which loop coil has the maximum detection voltage. If not reached, the coordinate calculation is stopped, and the center of the loop coil selected in the next detection operation is set.

On the other hand, the processor 8 inputs the detection voltages VR1 to VR48 for the input pen 4 (or the cursor 5) together with the input pen 4
The detection voltage V _θ proportional to the phase difference between the voltage and the current in the tuning circuit 41 (or the tuning circuit 51 of the cursor 5) is calculated by the arithmetic processing of the equation (2), and the detection voltage V _θ is always set to a predetermined threshold value. Comparing with the voltage. Therefore, at this time, the switch 411 of the input pen 4 (or the switch 511 of the cursor 5)
When is turned on, the processing device 8 detects this from the comparison result, and sends the coordinate value at this time to another electronic computer or the like not shown as the coordinate value of the designated position.

As one of the calculation methods for obtaining the coordinate value xp, there is a method of approximating the waveforms of the detection voltages VR1 to VR48 near the maximum value by an appropriate function and obtaining the coordinates of the maximum value of the function.

For example, in FIG. 6 (c), the maximum detection voltage VR3
And the detected voltages VR2 and VR4 on both sides thereof are approximated by a quadratic function, they can be calculated as follows (however, the coordinate value of the center position of each loop coil 11-1 to 11-48 is x1 to x48, and the interval is Δx.). First, from each voltage and coordinate value, VR2 = a (x2-xp) ² + b ... (3) VR3 = a (x3-xp) ² + b ... (4) VR4 = a (x4-xp) ² + b ... … (5) Here, a and b are constants (a <o). Further, x3−x2 = Δx (6) x4−x2 = 2Δx (7) By substituting equations (6) and (7) into equations (4) and (5) and rearranging, xp = x2 + Δx / 2 {(3VR2-4VR3 + VR4) / (VR2-2VR3 + VR4)} (8) .

Therefore, from the respective detection voltages VR1 to VR48, the maximum detection voltage obtained at the time of the level check and the detection voltages before and after it are extracted, and these and the loop coil 1 having the maximum detection voltage are extracted. The coordinate value xp of the designated position of the input pen 4 can be calculated by performing the operation corresponding to the above-mentioned equation (8) from the coordinate value (known) of the immediately preceding loop coil, and similarly, the designated position of the cursor 5 can be calculated. The coordinate value of can be calculated.

Further, as described above, the detection voltage for the input pen 4 is AD
Since the detection voltage for the cursor obtained from the converters 712 and 713 is obtained from the AD converters 714 and 715, the input pen 4 or the cursor 5 is brought close to the position detectable range of the position detection unit 1 together with the level check. Then, it is possible to detect which of the input pen 4 and the cursor 5 is approaching with the approach, and this can be displayed on a display or the like not shown.

Further, by attaching a microphone or the like to the position detection unit 1 and providing the processing device 8 with a voice recognition function,
Various commands can be given by voice, or the processing device 8 can be provided with a character recognition function to be used as a tablet for inputting handwritten characters.

In the above embodiment, a tuning circuit having a tuning frequency f0 and a phase difference of 0 ° between voltage and current, a tuning circuit having a tuning frequency f0 and a phase difference of 90 °, a tuning circuit having a tuning frequency of 3f0 and a phase difference of 0 °, And position indicators each having a tuning circuit having a tuning frequency of 3f0 and a phase difference of 90 ° are prepared, and the processing device 8 performs the arithmetic processing of the equation (8) for each output value of the AD converters 712 to 715. If so, the transmission circuit 7
It is also possible to detect the positions of the four position indicators at the same time without changing the configuration of the receiver circuit 8 or the receiver circuit 8.

Further, it is needless to say that the number of loop coils and the way of arranging the loop coils in the embodiments are examples, and the present invention is not limited to this.

FIG. 9 shows a second embodiment of the present invention, in which an example of position detection in the X and Y directions is shown. That is, in the figure, reference numeral 1a is a position detector in the X and Y directions, which is a set of two position detectors 1 in the first embodiment, which are superposed so that their loop coils are orthogonal to each other.
2a and 2b are selection circuits for the X and Y directions, 3a and 3b are connection switching circuits for the X and Y directions, and 605a and
Reference numeral 605b is a drive circuit in the X direction and direction, and 701a and 701b are amplifiers in the X direction and direction, which have the same configurations as the selection circuit 2, the connection switching circuit 3, the drive circuit 605, and the amplifier 701, respectively, in the first embodiment. is doing. Further, 605 is an XY switching circuit, which drives the AC signal from the phase shifter 603 into the driving circuit 605.
In addition to either a or 605b, it is for selecting the detection direction. Further, 8a is a processing device,
The processing device 8 is the same as the processing device 8 except that the position detection in the X direction and the position detection in the Y direction are performed alternately. The timing of the second and subsequent coordinate detection operations in the processing device 8a is shown in FIG. As described above, according to this embodiment, it is possible to easily detect the position (coordinates) of the input pen 4 and the cursor 5 in the two directions of the X direction and the Y direction. The other configurations and operations are similar to those of the first embodiment.

(Effect of the Invention) As described above, according to the present invention, a predetermined frequency and its n (= 2, 3, ...
...) Generate radio waves of a predetermined frequency to a plurality of position indicators each having a plurality of tuning circuits having one of the frequencies of the second harmonic as a tuning frequency, and each of the plurality of position indicators. Radio waves of a predetermined frequency or the frequency of the nth harmonic thereof reflected from the tuning circuit are detected by the radio wave detecting means of the tablet for each of the predetermined frequency and the frequency of the nth harmonic, and the coordinates are further detected. Since the calculating means calculates the coordinate value of the pointing position on the tablet of the plurality of position pointing devices with a finer precision than the arrangement interval of the plurality of loop coils, a tuning circuit is provided for each of the plurality of position pointing devices. It suffices to provide passive elements such as coils and capacitors for the configuration, eliminating the need for a cord,
Therefore, the cord does not become entangled and obstructed, or the wire is not broken due to fatigue, and heavy parts such as batteries and magnets are not required, which is light and low cost and battery replacement is troublesome. And the operability is extremely improved, and the coordinate values of a plurality of pointing positions on the tablet by a plurality of position pointing devices can be detected with a precision smaller than the arrangement interval of each loop coil, that is, a high precision, and a plurality of coordinates can be detected. You can enter values at the same time. Therefore, for example, when inputting a figure by providing selection areas for various commands around the coordinate input range, while inputting the shape of the figure with one position indicator, the type of line segment can be input with another position indicator. It is possible to specify a color and a color, and it is not necessary to greatly move the position of one position pointing device each time the above-mentioned various types are specified as in the conventional case, and it is possible to realize a device with good operability. Further, since the tablet does not require any special parts, it can be upsized and can be applied to an electronic blackboard or the like.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the position detecting device of the present invention, FIG. 2 is a diagram showing a specific configuration of an input pen, and FIG.
FIG. 4 is a diagram showing a specific configuration of a cursor, FIG. 4 is a diagram showing a detailed configuration of a tuning circuit, a transmission circuit and a reception circuit, FIG. 5 is a waveform diagram of each part of FIG. 4, and FIG. ) (B)
(C) is a timing chart showing a basic detection operation in the first embodiment, FIG. 7 is a chart showing a detection voltage obtained from each loop coil in the first detection operation, and FIG. FIG. 9 is a timing diagram showing the second and subsequent detection operations, FIG. 9 is a main part configuration diagram showing a second embodiment of the present invention, and FIG. 10 is a view similar to FIG. 6 in the second embodiment. 1 ... Position detection unit, 11-1 to 11-48 ... Loop coil,
2 ... selection circuit, 3 ... connection switching circuit, 4 ... input pen, 5 ... cursor, 6 ... transmission circuit, 7 ... reception circuit, 8 ... processing device, 41, 51 ... tuning circuit.

Claims (6)

[Claims] 1. A position detecting device for transmitting and receiving a signal between a position indicator and a tablet to detect a coordinate value on the tablet designated by the position indicator, wherein a predetermined frequency and its n (= 2,3, ...) A plurality of position indicators each having a plurality of tuning circuits with one of the frequencies of the second harmonic as a tuning frequency, and a plurality of loop coils are provided. A radio wave generating means for generating a radio wave and a radio wave having substantially the same frequency as the predetermined frequency or the frequency of the nth harmonic thereof reflected from the plurality of tuning circuits are detected for each of the predetermined frequency and the nth high frequency. A tablet having a radio wave detecting means, and the predetermined frequency and its n induced by the reflection in a plurality of loop coils constituting the radio wave detecting means.
A plurality of induced voltages for each frequency of the next harmonic, and coordinate calculation means for obtaining coordinate values of the pointing positions on the tablet of the plurality of position indicators with a precision finer than the arrangement interval of the plurality of loop coils. A position detecting device characterized by the above. 2. The position detecting device according to claim 1, wherein the electric wave generating means and the electric wave detecting means are alternately operated. 3. The position detecting device according to claim 2, wherein the loop coil forming the electric wave generating means and the loop coil forming the electric wave detecting means are used in common. 4. A position detecting section in which a plurality of loop coils are arranged in parallel in a position detecting direction, a selection circuit for sequentially selecting one loop coil from the plurality of loop coils, and a predetermined frequency and its n (= 2,3, ...) A plurality of position indicators each having a plurality of tuning circuits having one of the frequencies of the second harmonic as a tuning frequency, and an AC signal of the predetermined frequency supplied to the loop coil. A transmission circuit that generates a voltage, and an induction voltage having substantially the same frequency as the predetermined frequency or the frequency of the nth harmonic thereof in the induction voltage generated in the loop coil for each of the predetermined frequency and the frequency of the nth harmonic thereof. Detection circuit, a connection switching circuit that alternately connects the selected one loop coil to the transmission circuit and the reception circuit, and the predetermined frequency and the predetermined frequency generated in each loop coil. And coordinate calculating means for obtaining the coordinate value of the indicated position of the plurality of position indicators with a precision smaller than the arrangement interval of the plurality of loop coils from the induced voltage for each frequency of the nth harmonic. The position detecting device according to claim 3. 5. An X-direction and Y-direction position detection unit, in which a plurality of loop coils are arranged side by side in the X-direction and the Y-direction, respectively, and an X-direction and a Y-direction position detection unit.
X that sequentially selects one loop coil in the Y and Y directions
Direction and Y direction selection circuits, and a plurality of positions each having a plurality of tuning circuits having a predetermined frequency and one of the n (= 2,3, ...) Harmonics as a tuning frequency An indicator, a transmission circuit for generating an AC signal of the predetermined frequency to be supplied to the X and Y direction loop coils, and a predetermined frequency in the induced voltage generated in the X and Y direction loop coils. Alternatively, a receiving circuit for detecting an induced voltage having substantially the same frequency as the frequency of the nth harmonic thereof for each of the predetermined frequency and the frequency of the nth harmonic thereof, and one loop coil for the selected X direction and Y direction. And a connection switching circuit for connecting in the X direction and the Y direction, the predetermined frequency generated in each loop coil in the X direction and the Y direction and its n-th order Coordinate calculation for obtaining coordinate values of designated positions in the X and Y directions of a plurality of position indicators with a precision finer than the arrangement interval of the plurality of loop coils in the X and Y directions from the induced voltage for each harmonic frequency. The position detecting device according to claim 3, further comprising: 6. A plurality of tuning circuits each having a predetermined frequency and one of the frequencies of its nth harmonic as a tuning frequency and each having a plurality of tuning circuits whose phase difference between a voltage and a current is changed by operating a switch or the like. Position detector and the phase difference is detected from the induced voltage generated in the loop coil for each of the predetermined frequency and its nth harmonic, and the operating state of the switches and the like in the plurality of position indicators is detected. The position detection device according to any one of claims 1 to 5, further comprising an operation determination unit.