JPH03189716A - Position detector and its position pointer - Google Patents

Abstract

PURPOSE:To transmit a large quantity of switch information by transmitting the radio waves via a tablet, changing the phase angle or the frequency of a turning circuit via position pointing device in the prescribed timing, and then detecting the phase angle or the frequency of the radio wave received from the tuning circuit synchronously with the preceding timing. CONSTITUTION:The electric energy larger than a fixed level and the prescribed timing information are extracted out of the voltage induced at a tuning circuit of a position pointing device B with the radio wave received from a tablet A. Then each part of the device B is driven by the extracted electric energy. At the same time, the frequency or the phase angle of the tuning circuit is changed in accordance with operation of a switch, etc., in the specific timing set based on the prescribed timing information. In this case, the change of the frequency or the phase angle of a received signal is detected via the tablet A in the specific timing. Thus the operation of the device B is identified to the switch, etc. In such a constitution, a large quantity of switch information can be transmitted to the tablet A from the device B in a short time with no mistake.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement of a position detection device using radio waves and a position indicator thereof.

(Prior Art) Prior to filing this application, the applicant filed Japanese Patent Application No. 61-213970.
No. 63-70326 (hereinafter referred to as the prior application), a position is disclosed in which radio waves are transmitted and received between a tablet and a position indicator to determine the coordinate values of a position designated by the position indicator. A detection device was proposed.

To briefly explain the content of the earlier application, the tablet is equipped with a large number of loop coils arranged in parallel in the position detection direction.
An alternating current signal of a predetermined frequency is applied to the - loop coil to transmit radio waves, and the radio waves excite a tuned circuit built in the position indicator. At this time, radio waves generated by the tuned circuit are received by the loop coil and generate an induced voltage. By sequentially switching and repeating this for each loop coil, a voltage value depending on the distance to the position indicator is obtained for each loop coil, and from these, the coordinate values of the position designated by the position indicator are determined.

By the way, in this type of position detection device, in order to specify the position to be actually input, it is necessary to transmit some information from the position indicator to the tablet.

In the prior application, by connecting another capacitor (or coil) to the coil and capacitor constituting the tuning circuit via a switch, the tuning frequency is slightly changed depending on the operation of the switch, and this tuning A slight change in frequency was detected by the tablet as a change in phase angle, and was used as the information described above.

FIG. 2 shows an example of the above-described position indicator, in which a coil 1 and a capacitor 2 are connected in series to form a tuned circuit with a predetermined frequency. Also, capacitor 3.4
．． 5.6 have different capacitance values, and switch 7
．． 8.9.10 in parallel to capacitor 2. Therefore, the tuning frequency changes by a different frequency depending on the operated switch, and the tablet side can identify the operated switch from the phase angle of the received signal at that time.

FIG. 3 shows another example of the position indicator, in which the coil 11
and capacitor 12 are connected in series with each other to form a tuned circuit of a predetermined frequency. Further, the capacitor 13 is connected in parallel to the capacitor 12 via an analog switch 14. The code generator 15 includes a number of switches 16-1, 16-2 . ...16-n outputs a predetermined bit, e.g., an 8-bit binary code, in response to the state of the connected selection input terminal, and outputs the analog switch 1.
4 intermittently. Therefore, the tuning frequency changes to a predetermined frequency or a slightly different frequency depending on the binary code corresponding to the operation switch, and the tablet converts the pattern of change in the phase angle of the received signal at that time into a binary code. By converting to , the operated switch can be identified.

(Problem to be Solved by the Invention) However, since the phase angle detected by the tablet changes somewhat due to changes in ambient temperature, etc., in the case of the circuit shown in Fig. 2, the phase angle when identifying the operation of each switch is It is necessary to have a certain range of width, and for this reason, it is not possible to increase the number of distinguishable switches very much.

In addition, in the case of the circuit shown in FIG. 3, it is possible to provide the number of switches according to the number of bits of the code generator 15, but the code generator 15 operates at a unique timing unrelated to the tablet, and the analog switch 14, it takes a long time for the tablet to convert the pattern of phase angle changes into a binary code, and it also requires batteries to operate the analog switch and code generator. There were drawbacks.

In view of the above-mentioned problems, the present invention provides a position detection device and its position indicator that can transmit a large amount of switch information from a position indicator to a tablet without error and in a short time, and eliminates the need for a battery in the position indicator. The purpose is to realize a vessel.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a position indicator having at least a tuned circuit, and a coordinate value of a specified position by alternately transmitting and receiving radio waves to and from the position indicator. In a position detecting device consisting of a tablet that seeks (The tablet is equipped with means for detecting the phase angle or frequency of radio waves generated by the tuned circuit of the position indicator at a specific timing, and the electric energy for driving each part is generated from the induced voltage in the tuned circuit.) means for extracting predetermined timing information from the induced voltage generated in the tuned circuit; and changing the phase angle or frequency of the tuned circuit based on the operation of a switch or the like at a specific timing based on the predetermined timing information. a position detecting device provided in a position indicator with a means for causing the tuning, a tuning circuit, means for extracting electrical energy for driving various parts from the induced voltage generated in the tuning circuit, and We propose a position indicator consisting of means for extracting predetermined timing information from voltage, and means for changing the phase angle or frequency of a tuned circuit based on the operation of a switch or the like at a specific timing based on the predetermined timing information. do.

(Function) According to the present invention, electrical energy of a certain level or more and predetermined timing information are extracted from the induced voltage generated in the tuned circuit of the position indicator by radio waves transmitted from the tablet, and the electric energy is used to control the position indicator. Each part is driven, and its frequency or phase angle is changed at a specific timing based on the predetermined timing information according to the operation of a switch, etc. At this time, the frequency or phase angle of the received signal at the specific timing is changed using the tablet. A change in the phase angle is detected, and from this the operation of a position indicator switch or the like is identified.

(Embodiment) FIG. 1 shows a first embodiment of a position detection device and a position indicator thereof according to the present invention. In the figure, 21 is a sensing section, 22
23 is a selection circuit, 23 is a transmission/reception switching circuit, 24 is an oscillator, 25
2 is a voltage detection circuit, 26 is a phase comparator, and 27 is a processing device, which constitute the tablet A. Also, 31 is a coil, 32 is a capacitor, 33 is a power supply circuit, 34.3
5.36 is an envelope detector (hereinafter simply referred to as a detector).
, 37 is a signal generation circuit, 38 is an analog switch, C1
, C2, ---.-Cn is a capacitor, Sl, 82°.
...Sn is a switch, and these constitute the position indicator B.

The sense section 21 is constructed by overlapping a large number of loop coils arranged in parallel in the X direction at predetermined intervals and a large number of loop coils arranged in parallel in the Y direction at predetermined intervals. The selection circuit 22
The negative loop coil is selected from a large number of loop coils in the direction and the Y direction, and operates based on selection information from the processing device 27. The transmission/reception switching circuit 23 connects the selected negative loop coil in the X direction or Y direction to the oscillator 24.
and the voltage detection circuit 25, and operate based on a switching signal from the processing device 27. The oscillator 24 generates a reference clock of a predetermined frequency fO, and supplies this to the transmission/reception switching circuit 23 via the phase comparator 26, the processing device 27, and a low-pass filter and drive circuit (not shown).

The voltage detection circuit 25 includes an amplifier, a bandpass filter having the frequency fo as a passband, a detector, and a low-pass filter, and outputs a DC signal having a voltage value corresponding to the energy of the frequency fo acid component in the received signal. The phase comparator 26 is composed of a phase detector and a low-pass filter, and receives the reference clock of frequency fo and the received signal passed through the bandpass filter from the voltage detection circuit 25, and calculates the phase angle between the received signal and the reference clock, that is, the transmitted signal. A DC signal having a voltage value corresponding to the difference between the two is output.

The processing device 27 is composed of a well-known microprocessor, etc., and creates a transmission/reception switching signal from the reference clock of the frequency fo and supplies it to the transmission/reception switching circuit 23, and also controls the selection circuit 22 according to the flowchart described later to perform sensing. The loop coil of the section 21 is switched, and the output voltages of the voltage detection circuit 25 and the phase comparator 26 are converted into analog/digital (A/D), and predetermined arithmetic processing is executed to determine the position specified by the position indicator B. The coordinate values and operated switches are calculated.

The coil 31 and the capacitor 32 are connected in series and constitute a tuned circuit with a frequency fo.

The power supply circuit 33 is for creating plus (+) and minus (-) DC power supply voltages from the signals generated in the tuning circuit and supplying them to each circuit, that is, the signal generation circuit 37 and the analog switch 38. Yes, there are specific examples
As shown in the figure. In the circuit shown in FIG. 4, the capacitance value of the capacitor C is set to a value that generates the voltage necessary to drive each circuit during the burst mode period, which will be described later, and maintains this voltage until the next burst mode period. selected.

The detectors 34 to 36 convert the signals generated in the tuning circuit into signals for determining the initial mode, position detection mode, burst mode, and switch identification mode of the tablet A, which will be described later, and for creating the necessary timing. , each with different characteristics (time constants).

The signal generation circuit 37 generates various timing signals from the output signals of the detectors 34 to 36, and generates various timing signals at specific timings in the switch identification mode, in this case, the analog switch 38.
Create a timing to turn on. That is, the detector 34
When the output of the wave detector 35 falls below a predetermined voltage value VTH1, when the output of the wave detector 35 exceeds the voltage value VTH2, and furthermore, when the output of the wave detector 36 falls below the voltage value vTH3, and when the voltage value V. 114 is detected, and a trigger signal, a clock signal, and a control signal, which will be described later, are generated.

One end of the analog switch 38 is connected to one end of the capacitor 32, and the other end is commonly connected to one end of the capacitors C1 to Cn. The other ends of the capacitors C1 to Cn are connected to ground, that is, the other end of the capacitor 32, via switches 81 to Sn, respectively, and therefore, while the analog switch 38 is on, the switch operated at that time is Any of the capacitors 01 to Cn corresponding to 81 to Sn will be connected in parallel with the capacitor 32.

The values of capacitors C1 to Cn change the tuning frequency of the above-mentioned tuning circuit by a small preset value, and change the phase angle detected by tablet A.

FIG. 5 is a flowchart of processing in the processing device 27, and FIG. 6 is a signal waveform diagram of each part in the tablet position detection mode, burst mode, and switch identification mode, and the operation will be explained below according to these.

First, the processing device 27 of the tablet A
Sequentially select all the loop coils in the direction and Y direction, repeat the transmission and reception of radio waves for each loop coil, detect the strength of the received signal, and check whether the position indicator B is within the effective reading area of the sense unit 21. If not, and if it is within the area, it is detected which of the multiple loop coils in the X and Y directions is closest to the position indicator B (initial mode).

Specifically, first, information for selecting the negative loop coil of the sensing section 21 is sent to the selection circuit 22, and a signal for selecting the transmitting side is sent to the transmission/reception switching circuit 23.
A sine wave signal with a frequency fO based on the reference clock of the oscillator 24 is supplied to the - loop coil to generate a radio wave with the frequency fO. At this time, when the position indicator B is placed on the sensing section 21, the radio wave excites a tuned circuit consisting of a coil 31 and a capacitor 32, and generates an induced voltage at a frequency fo therein.

When the processing device 27 sends a signal for selecting the transmitting side to the transmission/reception switching circuit 23 for a certain period of time, it sends a signal for selecting the receiving side, and eliminates the radio waves generated by the loop coil. At this time, the induced voltage generated in the tuned circuit of the position indicator B gradually attenuates according to its loss and emits a radio wave with a frequency fO, but this radio wave reversely excites the loop coil mentioned above. Generates an induced voltage.

After the processing device 27 sends a signal for selecting the receiving side to the transmission/reception switching circuit 23 for a certain period of time, it sends out a signal again for selecting the sending side, and thereafter, the same transmission and reception of radio waves as described above is repeated for a total of four times with respect to the - loop coil. let The processing device 27 changes the information sent to the selection circuit 22 to switch the loop coil to be selected, and thereafter transmits and receives radio waves in the same manner as described above for all the loop coils in the X direction and the Y direction.

The induced voltage generated in the loop coil of the sensing section 21 during the aforementioned four reception periods is averaged by the bandpass filter of the voltage detection circuit 25, further detected, converted to a DC voltage, and sent to the processing device 27. Since the voltage value of the DC voltage is a value that depends on the distance between the position indicator B and the loop coil, it is determined whether the maximum value in the X direction and the Y direction is equal to or greater than a predetermined threshold value set in advance. By this, it is determined whether or not the position indicator B is within the effective reading area of the sensing unit 21, and if it is determined that it is within the area, the maximum values in the X and Y directions at that time are obtained. The loop coils are stored as the loop coils in the X and Y directions closest to the position indicator B, and the next position detection mode is activated. Note that if it is determined that the position indicator B does not exist within the area, the initial mode is repeated.

In the position detection mode, the processing device 27 selects information to sequentially select a predetermined number of loop coils, in this case eight loop coils, centering on the memorized loop coil in the X and Y directions from which the maximum induced voltage was obtained. The signal is sent to the circuit 22 to transmit and receive radio waves in the same manner as described above. At this time, it is determined whether the maximum value of the obtained induced voltage is greater than or equal to the predetermined threshold,
If it is below the threshold, the process returns to the initial mode described above. In addition, if it is above the threshold value, the X direction and Y direction are
Find the coordinates of a specified position in a direction. Note that the specific method of calculating the coordinate values is the same as that of the previous application described above, so it will not be described in detail.

In the position detection mode described above, as shown in Fig. 6, radio waves are transmitted four times for each of the eight loop coils in the X direction and the Y direction, a total of 64 times (signal a).
, induced voltages of different levels are generated at both ends of the capacitor 32 due to the difference in distance between the position indicator B and the loop coil, as shown in the signal diagram. , the output of the detector 35 does not exceed the voltage value vTH2 in the position detection mode, the signal generation circuit 37 does not operate, and the analog switch 38 does not operate.

When the position detection mode ends, the processing device 27 sends information for selecting the X-direction (or Y-direction) loop coil for which the maximum induced voltage was obtained in the position detection mode to the selection circuit 22, and also outputs the burst mode and the selection circuit 22. Following this, switch identification mode is activated. In the burst mode, only radio wave transmission is performed continuously for a certain period of time, and in the switch identification mode, radio wave transmission and reception is repeated a predetermined number of times, in this case four times.

During the burst mode, the tuning circuit of position indicator B has
A continuous large-level induced voltage is generated, which charges the capacitor C in the power supply circuit 33.

Further, in the switch identification mode, a large level of induced voltage is generated during all four transmissions and receptions of radio waves.

Therefore, the output d of the wave detector 35 exceeds the voltage value VTH2 as shown in FIG. 6, and the signal generating circuit 37 is activated. The signal generation circuit 37 detects when the output e of the detector 36 falls below the voltage value vTH3 and when it exceeds the voltage value vTH4, and generates a trigger signal f and a clock signal g, and furthermore,
It detects when the output C of the wave detector 34 falls below the voltage value vTH1, and generates a control signal (however, the trigger signal f and tarok signal g are not used externally).

As a result, the signal generating circuit 37 outputs a control signal that is at a high level only during the period approximately corresponding to the third and fourth transmission/reception periods of radio waves, and the analog switch 38 is turned on. When the analog switch 38 is turned on, as described above, the capacitors C1 to Cn corresponding to the switches 81 to Sn operated at that time are connected in parallel with the capacitor 32, and the tuning frequency thereof changes slightly.

The processing device 27 of the tablet A processes the third and fourth phase comparison outputs j obtained from the phase comparator 26.
The value obtained during the second radio wave transmission/reception period (detection phase),
Other than that, here, the values (reference phase) obtained during the first and second radio wave transmission/reception periods are read and the difference therebetween is determined. The reference phase is that the tuned circuit of position indicator B is coil 3.
1 and capacitor 32, and the detection phase corresponds to the tuning frequency of a tuned circuit in which capacitors C1 to Cn are connected to capacitor 32 in accordance with switches 81 to Sn that are turned on at that time. , the difference corresponds only to the capacitance value of the connected capacitor. Therefore, if the phase difference when each switch 81-Sn is operated and the capacitors C1-Cn are connected is calculated and stored in advance, the operated switch can be identified from the obtained phase difference.

Note that the obtained coordinate values of the designated position and switch information are transferred to a host computer (not shown), etc., and used for various processing.

According to the embodiment described above, it is possible to obtain a phase angle difference that depends only on the capacitance value of the capacitor corresponding to the operated switch, so it is possible to provide a larger number of capacitors, that is, a larger number of switches than before. Further, since the driving power for each part of the position indicator uses the power stored in the capacitor of the power supply circuit during the burst mode period, there is no need to provide a battery or the like. Further, instead of providing a large number of switches and capacitors, it is also possible to provide a capacitor whose capacitance value changes continuously according to the operation, and to determine the amount of operation.

FIG. 7 shows a second embodiment of the present invention, in which information corresponding to operation switches is transmitted in an 8-bit binary code.

That is, in the figure, 28 is a processing device, which is the same as the processing device 27 of the first embodiment except that the operation in the switch identification mode is slightly different. The processing device 28, a sense section 21 similar to the above, a selection circuit 22, a transmission/reception switching circuit 23,
The oscillator 24, the voltage detection circuit 25, and the phase comparator 26 constitute a tablet A'.

Further, 39 is a signal generation circuit, 40 is a code generator, and 41
is a parallel-to-serial (P-8) conversion circuit, 42 is a capacitor, and a coil 31 similar to the above, a capacitor 32, a power supply circuit 33, detectors 34 to 36, and an analog switch 38 constitute a position indicator B'. be done.

The signal generation circuit 39 generates various timing signals from the output signals of the detectors 34 to 36, and generates various timing signals at specific timings in the switch identification mode, in this case, the P-8 conversion circuit 4.
Create the timing to drive 1. That is, the detector 34
When the output of VTI11 is lower than the predetermined voltage value VTI11,
It detects when the output of the wave detector 35 exceeds the voltage value v1H2, and also when the output of the wave detector 36 falls below the voltage value vTH3 and exceeds the voltage value VTl14, and generates a trigger signal and a clock signal to be described later. create.

The code generator 40 generates an 8-bit binary code according to the operated switch among the directly attached switches 81 to Sn, and a specific example thereof is shown in FIG.

The P-8 conversion circuit 41 converts the binary code from the code generator 40 every time a rising edge of the clock signal is inputted until the output of the detector 34 falls below the voltage value VTH1 after the rising edge of the trigger signal is inputted. is sent one bit at a time to the analog switch 38, which is controlled on and off. The capacitor 42 is connected to the capacitor 32 via the analog switch 38.
Therefore, the tuning frequency changes slightly between the on period and the off period of the analog switch 38, and the phase angle detected by the tablet A' also changes.

FIG. 9 is a flowchart of processing in the processing device 28, and FIG. 10 is a signal waveform diagram of each part. The operation will be described below, but the initial mode, position detection mode, and burst mode are the same as those in the first embodiment, so their explanations will be omitted.

In the switch identification mode, the processing device 28 repeatedly transmits and receives radio waves a predetermined number of times, 16 times in this case (signal k).

In this case, a large induced voltage g is generated across the capacitor 32 during all 16 transmissions and receptions of radio waves. Therefore, at this time, the output 0 of the detector 36 exceeds the voltage value VTH4 for all 16 radio wave transmissions and receptions, and the signal generation circuit 39 synchronizes every two of the 16 radio wave transmissions and receptions. Eight clock signals q are created,
This will be input to the P-8 conversion circuit 41. In addition, in the signal generation circuit 39, the output n of the detector 35 and the detector 3 based on the induced voltage g during the burst mode period are
Similarly to the signal generating circuit 37 of the first embodiment, the trigger signal p is generated by detecting when the output 0 of 6 exceeds the voltage value vTH2 and falls below the voltage value VTH3, respectively.

As described above, the P-8 conversion circuit 41 outputs the 8-bit binary code supplied from the code generator 40 one bit at a time each time the clock signal is input, so it is The second time, the first bit, and
3rd and 4th, 5th and 6th, 7th and 8th, 9th and 10th, 11th and 12th, 13th and 14th, The 15th and 16th times are the 2nd. Third. 4th゜5th.
6th. 7th. The 8th bit is output as signal r. The analog switch 38 is controlled to be turned on or off depending on the level of the signal r, and when it is on, the capacitor 42 is connected across the capacitor 32, and its tuning frequency changes slightly.

Of the phase comparison output t obtained from the phase comparator 26, the processing device 28 of the tablet A' processes the first and second comparison outputs, the third and fourth comparison outputs, . . . The value obtained during the 15th and 16th radio wave transmission/reception period is 2
Convert to hexadecimal code. Specifically, the capacitance value of the tuning circuit of the position indicator A- increases when the analog switch 38 is on, and the tuning frequency becomes lower, that is, the phase angle is delayed, so that there is no gain during the above-mentioned radio wave transmission and reception period. Of the values given,
The value corresponding to the later phase angle is set to bit “1”, and
Any other value is converted into an 8-bit binary code as bit "0".

The 8-bit binary code obtained in this way matches the binary code generated by the code generator 40, so if you memorize the codes generated when the switches 81 to Sn are operated in advance, you can obtain a profit. The operated switch can be identified from the binary code given.

According to the embodiment, since the binary code can be transmitted from the position indicator B' in synchronization with the timing of the tablet A', it is possible to recognize the binary code in an extremely shorter time than in the past. A larger number of switches than in the example, 254 in this case (excluding binary codes of all "0" and all "1"), can be provided.

Note that in the second embodiment, the P-8 conversion circuit can be replaced with a multiplexer (however, the signals to be generated by the signal generation circuit also need to be slightly changed). In addition, since the value corresponding to the reference phase can also be obtained in the second embodiment, it can also be combined with a system that changes the phase according to the operation and detects this as in the first embodiment. . Further, the number of bits of the binary code in the second embodiment is just an example, and it goes without saying that the number of bits is not limited to this.

In addition, in the first and second embodiments, the transmission and reception of radio waves is
Although the data of - is transmitted by repeating the above, the present invention is not limited to this. Also, the first and! In the second embodiment, the position indicator is provided with three detectors, but it is also possible to use only the detector 36, and if the output is passed through an appropriate integrator, the detector 34.
It is possible to obtain an output of 5.

Further, since the analog switch 38 of the position indicator B of the first embodiment receives the positive and negative bipolar signals generated in the tuning circuit as is, regardless of whether it is on or off, the driving voltages are also positive and negative. For this reason, the position indicator B of the first embodiment requires a power supply circuit 33 that can supply positive and negative drive voltages, but the position indicator B of the second embodiment For the reason described below, in the device B', it is sufficient to have either a positive or negative driving voltage, and therefore, the power supply circuit 33
Half of the configuration in can be omitted. That is, when the analog switch 38 of the position indicator B' of the second embodiment is on, both terminals are grounded and almost no voltage is applied to it, and when it is off, the tuning is not applied. Both positive and negative polarity signals generated in the circuit are input through the capacitor 42, but the capacitance value of the capacitor 42 is very small compared to the capacitor 32 (it is used to slightly change the tuning frequency). because there is),
Since the impedance to the frequency fo is extremely large, even if there is no positive or negative driving voltage and the signal of the polarity with no driving voltage is clamped by the protection circuit in the analog switch 38, the signal in the tuned circuit will not be affected. (In addition, in the position indicator B of the first embodiment, the capacitors C1 to
If Cn and switches 81 to Sn are provided between one end of the capacitor 32 and one end of the analog switch 38, and the other end of the analog switch 38 is grounded, the power supply circuit 3
Half of the configuration in 3 can be omitted. ).

(Effects of the Invention) As explained above, according to the present invention, a radio wave capable of causing an induced voltage containing electric energy of a certain level or more and predetermined timing information to be generated in the tuning circuit of a position indicator is transmitted from a table-soto. In the position indicator, the electric energy is extracted to drive each part, and predetermined timing information is extracted, and the phase angle or frequency of the tuned circuit is adjusted based on the operation of a switch or the like at a specific timing based on this information. change,
Furthermore, since the tablet side detects the phase angle or frequency of the radio waves from the tuned circuit in synchronization with the specific timing, at least two pieces of information indicating the operation status of switches etc. are transmitted from the position indicator to the tablet without error. This makes it possible to eliminate errors caused by changes in the surrounding environment, and allows for the transmission of more switch operation information.
No power supply is required to drive each part of the position indicator,
There is no need to provide batteries or the like.

Furthermore, if the phase angle or frequency of the tuned circuit is changed according to a specific code corresponding to the operation of a switch, etc., it is possible to transmit even more operation information of a switch, etc. in a short time. For example, there are advantages such as being able to configure a cordless and battery-less keyboard device that can operate on a tablet.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a first embodiment of a position detection device and its position indicator according to the present invention, Fig. 2 is a block diagram showing an example of a conventional position indicator, and Fig. 3 is a block diagram showing a conventional position indicator. 4 is a circuit diagram showing a specific example of the power supply circuit, FIG. 5 is a flowchart of processing in the processing device of the first embodiment, and FIG. 6 is the first embodiment. Signal waveform diagram of each part in
FIG. 7 is a block diagram showing a second embodiment of the present invention, FIG. 8 is a circuit diagram showing a specific example of a code generator, FIG. 9 is a flowchart of processing in the processing device of the second embodiment, and FIG. Figure 10 is the second
FIG. 3 is a signal waveform diagram of each part in the embodiment. 21...Sense unit, 22...Selection circuit, 23...
Transmission/reception switching circuit, 24... Oscillator, 25... Voltage detection circuit, 26... Phase comparator, 27.28... Processing device, 31-... Coil, 32, 42. C1~Cn...
:I inductor, 33...power supply circuit, 34, 35.36
...Envelope detector, 37.39...Signal creation circuit,
38... Analog switch, 40... Code generator, 41... Parallel-serial conversion circuit, 81~Sn
···switch. Figure 2 Diagram showing a specific example of the code teacher device Δm OI'Flt

Claims (6)

[Claims] (1) In a position detection device consisting of a position indicator having at least a tuning circuit and a tablet that obtains coordinate values of a specified position by alternately transmitting and receiving radio waves to and from the position indicator, the tuning circuit of the position indicator means for transmitting a radio wave capable of generating an induced voltage containing electrical energy of a certain level or more and predetermined timing information; and a phase of the radio wave generated by a tuned circuit of the position indicator at a specific timing based on the predetermined timing information. The tablet is equipped with a means for detecting the angle or frequency, a means for extracting electrical energy for driving each part from the induced voltage generated in the tuned circuit, and a means for extracting predetermined timing information from the induced voltage generated in the tuned circuit. A position detection device characterized in that a position indicator is provided with a means for extracting the information and a means for changing the phase angle or frequency of the tuned circuit based on the operation of a switch or the like at a specific timing based on the predetermined timing information. . (2) A tablet equipped with a means for transmitting radio waves that can cause an induced voltage that continues for a certain period of time in a tuned circuit of a position indicator and an intermittent induced voltage that follows a predetermined period, and a certain period of time that occurs in the tuned circuit. The position detection device according to claim 1, further comprising a position indicator provided with means for extracting a continuous induced voltage and a subsequent intermittent induced voltage of a predetermined period as predetermined timing information. . (3) A tablet equipped with a means for converting changes in phase angle or frequency detected at a specific timing into a code, and a means for changing the phase angle or frequency of a tuned circuit according to a specific code according to the operation of a switch, etc. Claim (1) or (2) characterized in that it is provided with a position indicator provided therein.
The position detection device described. (4) a tuned circuit, means for extracting electrical energy for driving various parts from the induced voltage generated in the tuned circuit, and means for extracting predetermined timing information from the induced voltage generated in the tuned circuit; A position indicator comprising means for changing the phase angle or frequency of a tuning circuit based on an operation of a switch or the like at a specific timing based on the predetermined timing information. (5) The device according to claim (4), further comprising means for extracting, as predetermined timing information, an induced voltage that occurs in the tuned circuit and continues for a certain period of time and an intermittent induced voltage that follows this in a predetermined period. position indicator. (6) The position indicator according to claim 4 or 5, further comprising means for changing the phase angle or frequency of the tuning circuit according to a specific code corresponding to the operation of a switch or the like.