JPH07111671B2 - 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 to increase the resolution, SN and stability will deteriorate, and therefore the resolution will increase. It was difficult to raise the position, 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 each having a plurality of tuning circuits each having a plurality of tuning circuits having one of a plurality of different frequencies as a tuning frequency, and a plurality of loop coils, wherein the plurality of different ones A tablet having a radio wave generating means for generating a radio wave of a frequency and a radio wave detecting means for detecting radio waves of substantially the same frequency as the plurality of different frequencies reflected from the plurality of tuning circuits for each of the plurality of different frequencies, A plurality of inductions for each of the plurality of different frequencies that are induced by the reflection in the plurality of loop coils that constitute the radio wave detection means. A position detecting device is proposed, which comprises coordinate calculating means for calculating coordinate values of a plurality of position pointing positions on the tablet with a finer accuracy than the arrangement intervals of the plurality of loop coils from the voltage.

(Operation) According to the present invention, when radio waves having a plurality of different frequencies are generated by the radio wave generating means composed of a plurality of loop coils, the radio waves are respectively tuned by a plurality of position pointing devices that perform position designation on the tablet. The plurality of tuning circuits, which are tuned to, or received by, the circuit, respectively emit, or reflect, radio waves having substantially the same frequency as the plurality of different frequencies. The reflected radio waves having substantially the same frequency as the plurality of different frequencies are detected for each of the plurality of different frequencies by the radio wave detection means including a plurality of loop coils of the tablet, and the coordinate calculation means further detects the plurality of positions. The coordinate value of the pointing position of the pointing device on the tablet is calculated with a finer precision than the arrangement interval 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 first alternating current which will be described later. At the signal frequency f1, the voltage and current phases are set to values that resonate (tune) in phase. The capacitor 414 is connected to both ends of the coil 412 and the capacitor 413 via the switch 411,
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 detector 1 to
When the core body 43 is pushed into the pen shaft 42, it is pressed by the rear end of the pen shaft 42 through the coil spring 45 and 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 resonant circuit, and the numerical values of the coil 512 and the capacitor 513 are the second alternating current to be described later. At the signal frequency f2, the voltage and current phases are set to values that resonate (tune) in phase. The capacitor 514 is connected to both ends of the coil 513 and the capacitor 513 via the switch 511,
When the switch 511 is turned on, it 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, 602 are waveform shaping circuits, 603, 604 are phase shifters,
Reference numeral 605 is a drive circuit, which constitutes 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 the first and second AC signals and the transmission / reception switching signal, controls the switching of each loop coil based on the output of the receiving circuit 7, and performs a plurality of tuning operations. The coordinate value of the circuit, that is, the coordinate value of the designated position of the plurality of position indicators is 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 a first AC signal of a frequency f1, for example, 500 kHz, for example, a rectangular wave signal A, based on a clock from an oscillator (not shown), and a frequency f2, for example, 625 kHz.
Second AC signal, for example, a rectangular wave signal B is generated, and further, a transmission / reception switching signal C having a frequency of 15.625 kHz is generated.

The rectangular wave signals A and B are sent to the waveform shaping circuits 601 and 602, respectively, where the waveforms are shaped and further sent to the phase shifters 603 and 604, respectively. The phase shifter 603 creates a signal in which the phase of the rectangular wave signal A is kept as it is (0 °) and a signal A ′ (not shown) delayed by 90 °, and sends them to the phase detectors 704 and 705, respectively. In addition, the phase shifter 604 outputs a signal in which the phase of the rectangular wave signal B is unchanged (0 °), and
A 90 ° delayed signal B '(not shown) is created and sent to phase detectors 706 and 707, respectively.

On the other hand, the rectangular wave signals A and B are converted into a balanced signal by the drive circuit 605 and sent to the connection switching circuit 3,
Since the connection switching circuit 3 is switching-controlled by the signal C, the signal output from the connection switching circuit 3 to the selection circuit 2 is a signal D that outputs or does not output a 500 kHz pulse signal every 32 μsec. It becomes a signal E that outputs or does not output a 625 kHz pulse signal every 32 μsec.

The signals D and E are sent via the selection circuit 2 to one loop coil of the position detector 1, for example, 11-i. At this time, the loop coil 11-i outputs the signals D and E. Generates radio waves based on.

At this time, if the input pen 4 is held in a substantially upright state near the loop coil 11-i of the position detector 1, the signal D
The radio wave generated by this excites the coil 412 of the input pen 4 and generates an induction voltage F in synchronization with the signal D in the tuning circuit 41 thereof. On the other hand, based on the signal E, the loop coil 11
The radio wave generated from -i excites the coil 512 of the cursor 5 placed at another position on the position detection unit 1, and the induction voltage G synchronized with the signal E is generated in the tuning circuit 51 thereof.

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

On the other hand, the currents flowing through the tuning circuits 41 and 51 based on the induced voltages F and G 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 H thus generated is generated.

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

Since the bandpass filter 702 is a filter having a pass band centered on the frequency f1, only the induced voltage component due to the tuning circuit 41 in the signal H appears in the output I, and similarly, the bandpass filter 703 changes the frequency f2 to the frequency f2. Since it is a filter having a pass band at the center, only the induced voltage component in the signal H due to the tuning circuit 51 appears at its output J.

The signal I is input to the phase detectors 704 and 705, respectively, and the signal J 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 I is the rectangular wave signal A.
If it matches the phase of, the signal K, which is the signal I just inverted to the plus side, is output. The signal K is converted into a flat signal L having a voltage VL by a low pass filter 708 having a sufficiently low cutoff frequency.

Further, the rectangular wave signal A ′ is input to the phase detector 705 as a detection signal. At this time, if the phase of the signal I matches the phase of the rectangular wave signal A ′, the signal I is output as described above. Outputs the inverted signal to the plus side. The signal is converted into a flat signal by the low pass filter 709 similar to the above.

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

Further, the rectangular wave signal B'is input to the phase detector 705 as a detection signal. At this time, if the phase of the signal J matches the phase of the rectangular wave signal B ', the signal J is output as described above. Outputs the inverted signal to the plus side. The signal is converted into a flat signal by the low pass filter 711 similar to the above.

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 I and J
And the rectangular wave signals A and B 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. 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 position delay is present 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, in the cursor 5, when the switch 511 is turned on, 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 J is delayed. Also lags the phase of the rectangular wave signal B 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 C 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 and
Although not shown, 20 pulse signals of 625 kHz (the fifth signal
For convenience of drawing, only five of them are shown in the figure. ) Is sent.

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, 713 are converted into a detection voltage 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 in the same manner as described above, the input pen 4 and the loop coil 11-2. A detection voltage VR2 proportional to the distance between the two is obtained and stored. Hereinafter, similarly, the loop coils 11-3 to 11-48 are sequentially connected to the connection switching circuit 3, and the detection voltage proportional to the distance from the input pen 4 for each loop coil as shown in FIG. 6 (c). VR1 to VR48 (however, only a part of them is shown in analog form in FIG. 6 (c)) are 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 performs the arithmetic processing of the equation (1) on the output values of the AD converters 714 and 715 when the selection circuit 2 is switched in the same manner as described above, and the distance between each loop coil and the cursor 5 is obtained. The detection voltage proportional to 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 f1 and a phase difference of 0 ° between voltage and current, a tuning circuit having a tuning frequency f1 and a phase difference of 90 °, a tuning circuit having a tuning frequency f2 and a phase difference of 0 °, And a position indicator having a tuning frequency f2 and a tuning circuit having 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, 1a is a position detection unit in the X and Y directions,
In this embodiment, two sets of the position detecting units 1 are stacked and their loop coils are superposed so as to be orthogonal to each other. 2a and 2b are selection circuits for the X and Y directions, and 3a and 3b.
b is an X-direction and Y-direction connection switching circuit, 605a and 605
b is a drive circuit in the X direction and direction, and 701a and 701b are X circuits.
The direction and direction amplifiers have the same configurations as the selection circuit 2, the connection switching circuit 3, the drive circuit 605, and the amplifier 701 in the first embodiment, respectively. Further, reference numerals 606 and 607 denote XY switching circuits for applying the AC signals from the phase shifters 603 and 604 to only one of the drive circuits 605a and 605b to select the detection direction. The processing device 8a is the same as the processing device 8 except that the position detection in the X direction and the Y direction is alternately performed.
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 plurality of position indications each having a plurality of tuning circuits having one of a plurality of different frequencies as a tuning frequency are generated by the radio wave generating means of the tablet. Radio waves of a plurality of different frequencies to the device, and radio waves having substantially the same frequency as the plurality of different frequencies reflected from the tuning circuits of the plurality of position pointing devices are mutually detected by the radio wave detection means of the tablet. Detected for each of a plurality of different frequencies, further coordinate calculation means for calculating the coordinate value of the pointing position on the tablet of the plurality of position indicators with a finer precision than the arrangement interval of the plurality of loop coils, It suffices to provide passive elements such as coils and capacitors for constructing the tuning circuit in each of the plurality of position indicators, and the code becomes unnecessary,
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, the position detecting device comprising a plurality of frequencies different from each other. A plurality of position indicators each having a plurality of tuning circuits having one frequency as a tuning frequency, and a plurality of loop coils, a radio wave generating means for generating radio waves of a plurality of different frequencies, and the plurality of tuning circuits. A tablet having a radio wave detecting means for detecting radio waves of substantially the same frequency as the plurality of different frequencies reflected from each other, and a plurality of loop coils constituting the radio wave detecting means The spacing between the plurality of loop coils is smaller than the plurality of induced voltages induced at the different frequencies. Position detecting device characterized by comprising a coordinate calculation means for calculating the coordinate value of the indicated position on the tablet of the plurality of position indicators with precision. 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 plurality of frequencies different from each other. A plurality of position indicators each having a plurality of tuning circuits having one frequency as a tuning frequency, a transmission circuit for generating AC signals of a plurality of different frequencies to be supplied to the loop coil, and a loop circuit. In the induced voltage, the receiving circuit for detecting the induced voltage of substantially the same frequency as the plurality of different frequencies for each of the plurality of different frequencies, and the selected one loop coil in the transmission circuit and the receiving circuit alternately. Based on the connection switching circuit to be connected and the induced voltage generated in each loop coil for each of the plurality of different frequencies, the plurality of loop coils are connected. Position detecting device ranging third claim of claims, characterized in that a coordinate calculation means for calculating the coordinate value of the designation position of the plurality of position indicators with finer precision mounting pitch. 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, a plurality of position indicators each having a plurality of tuning circuits having one of a plurality of different frequencies as a tuning frequency, and the X direction and Y direction loop coils In the induced voltage generated in the transmission circuit that generates the AC signals of the plurality of mutually different frequencies and the induced voltage generated in the loop coil in the X direction and the Y direction, the induced voltages of substantially the same frequency as the plurality of different frequencies are different from each other. A receiving circuit that detects each of a plurality of frequencies; an X-direction and Y-direction connection switching circuit that alternately connects the selected one loop coil in the X-direction and the Y-direction to the transmitting circuit and the receiving circuit; And a plurality of induced voltages of different frequencies generated in the respective loop coils in the Y direction, 4. The position according to claim 3, further comprising: coordinate calculating means for calculating coordinate values of the X-direction and Y-direction indicated positions of the plurality of position indicators with a precision smaller than the disposition intervals of the loop coils. Detection device. 6. A plurality of position indicators each having a plurality of tuning circuits in which one of a plurality of frequencies different from each other is used as a tuning frequency and a phase difference between a voltage and a current is changed by operating a switch or the like. It is characterized by further comprising operation determining means for detecting the phase difference from the induced voltages of the plurality of different frequencies generated in the loop coil, and detecting an operation state of the switch or the like in the plurality of position indicators. The position detecting device according to any one of claims 1 to 5.