JPH0812583B2 - Position indicator in coordinate input device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position pointing device for a coordinate input device, and more particularly to a position pointing device which does not require a connecting cable for connecting to the coordinate input device or a battery for driving an oscillator. It is related to vessels.

[0002]

2. Description of the Related Art As a conventional position indicator of this type, an exciting coil is provided at one end of a casing, an alternating current is supplied to the exciting coil to generate an electromagnetic wave, and thereby a local portion of a tablet of a coordinate input device. The electromagnetic variable locally generated at a predetermined timing from the tablet of the coordinate input device by generating an induced voltage or by providing a detection coil at one end of the casing, By detecting from the induced voltage generated in the detection coil,
There was something that made it possible to specify an arbitrary position. However, this position indicator requires a connection cable for supplying an alternating current to the exciting coil or a connection cable for detecting an electromagnetic variable from the detection coil,
There was a problem that the operability at the time of position specification work was not good.

In order to eliminate the above-mentioned drawbacks of the conventional position indicator, an oscillator for supplying an alternating current to the exciting coil and a battery for driving the oscillator are provided to eliminate the need for the connecting cable as described above. Although such a battery has already been proposed, it has a drawback that it requires replacement or charging of the battery, the work is complicated, the weight of the battery is heavy, and the operability is not improved so much. .

Further, as another conventional position indicator, a magnetic body is provided at one end of a housing, a plurality of drive lines are arranged in parallel on a tablet of a coordinate input device, and an alternating current is sequentially supplied thereto. By changing the induced voltage by changing the electromagnetic coupling between a plurality of detection lines that are arranged in parallel at right angles and sequentially detect the induced voltage, by bringing the magnetic substance into close proximity or contact with the tablet, There was something that made it possible to specify an arbitrary position. However, with this position indicator, it is possible to eliminate the battery along with the connection cable as described above, but even when it is simply held on the tablet, its position may be detected and input incorrectly. There was a drawback.

Furthermore, in order to eliminate the drawbacks of the other conventional position indicators described above, only when the position indicator is operated by the operator, for example, only when the position indicator is pressed against the tablet. There is also one provided with an LC circuit for changing the inductance of the magnetic material to enable position detection (see Japanese Patent Laid-Open No. 59-3537), but no operator's operation is performed, that is, a position indicator is provided. Since the position cannot be detected at all when it is not pressed against the tablet, it is not possible to display the indicated position on the display screen to confirm it before actually inputting, especially when inputting handwritten characters or handwritten figures. When using it as a device, it is not possible to confirm the positional relationship (distance) with the part that has already been input and displayed on the display screen, and you can enter handwritten characters and handwritten figures as intended. There is a drawback that it can not.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and does not require a connecting cable with a coordinate input device or a battery for driving an oscillator. An object of the present invention is to provide a position indicator in a coordinate input device capable of accurately notifying whether or not it has been added.

[0007]

In order to achieve the above object, the present invention provides a position indicator used in a coordinate input device according to claim 1, wherein the position indicator is constantly closed. The first state composed of the first tuning circuit and the second state composed of the second tuning circuit configured to be connected to the first tuning circuit by the operation of the operator are operated by the operator. The position indicator is configured to be tuned to a radio wave transmitted from the tablet in any of the first and second states, and the position indicator is configured to be selectable arbitrarily and alternatively. The indicator, due to the tuning,
A position indicator in a coordinate input device configured to notify whether the position indicator is in the first state or the second state together with position information by different radio waves transmitted to the tablet is proposed. To do.

Further, in the present invention, the first tuning circuit comprises at least one coil and a capacitor, and the second tuning circuit is operated by a switch operated by an operator.
The position pointing device according to claim 1, wherein the tuning frequency of the first tuning circuit and a predetermined element that makes the tuning frequency different from each other are connected to the first tuning circuit.

Further, according to a third aspect of the present invention, in any of the first and second states, it is constituted so as to be tuned to the radio wave of the same frequency transmitted from the tablet, and the position indicator is provided together with the position information. The position indicator according to claim 1 or 2, which is configured to notify whether the state is the first state or the second state by radio waves having different phases transmitted to the tablet.

[0010]

According to the first aspect of the present invention, when the coordinate input device is positioned on the tablet, it is in the first state or the second state, that is, whether or not the operation by the operator is applied. Regardless, the first or second tuning circuit is excited based on the radio wave transmitted from the tablet to generate an induced voltage. The induced voltage causes a current to flow in the first or second tuning circuit, and the current causes the electric wave to be transmitted from the first or second tuning circuit to the tablet of the coordinate input device.
This determines the location on the tablet. At this time, when the operation state is changed, the operating tuning circuit is switched to either the first tuning circuit or the second tuning circuit, which causes the tablet of the coordinate input device to transmit different radio waves,
As a result, the position information on the tablet is transmitted not only when the operation is performed by the operator but also when the operation is not performed.

According to the second aspect, different radio waves are transmitted to the tablet by the first and second tuning circuits having different tuning frequencies, and the operation is performed by the operator as well as when the operation is performed. The position information on the tablet is transmitted even when it is not added.

Further, according to claim 3, radio waves having different phases are transmitted to the tablet by the first and second tuning circuits that tune to radio waves of the same frequency transmitted from the tablet, whereby the operation by the operator is performed. The position information on the tablet is transmitted not only when the operation is performed but also when the operation is not performed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a position indicator in a coordinate input device of the present invention, for example, an input pen 10, which is located inside a pen shaft 11 made of a non-metal material such as synthetic resin from its tip end. A core body 12 such as a ballpoint pen, and the core body 12
Ferrite core 1 having a through hole capable of slidably accommodating
3, a coil spring 14, a switch 151, a coil 152 wound around the ferrite core 13, and a capacitor 153.
, 154 and variable capacitor 155
Are integrally combined and built in, and a cap 16 is attached to the rear end thereof.

The capacitor 153 and the variable capacitor 15
As shown in FIG. 2, 5 are connected in parallel with each other, and both ends thereof are connected to the coil 152 to form a well-known parallel resonance circuit. The coil 152 and the capacitor 153
The numerical values of the variable capacitor 155 and the variable capacitor 155 are selected as values that resonate (tune) to the frequency of the radio wave transmitted from each loop coil of the position detecting unit described later.

On the other hand, the capacitor 154 is connected to both ends of the coil 152 via the switch 151, and the switch 151
Is turned on, the phase of the current in the parallel resonance circuit is delayed by a predetermined angle. In addition, switch 15
1 presses the tip of the core body 12 against the input surface (not shown) of the position detection unit to move the core body 12 to the pen shaft 11
When it is pushed inward, it is pushed by the rear end of the coil spring 14 and turned on.

Here, the above-mentioned coil 152 and capacitor
A circuit consisting of 153 and a variable capacitor 155 constitutes a first closed circuit which is normally closed, and a switch 151,
Coil 152, capacitors 153, 154 and variable capacitor
A circuit consisting of 155 is operated (here, the core 12 is connected to the pen shaft 1
The second tuning circuit is configured by being connected to the first tuning circuit by turning on the switch 151 by pushing the switch into the first tuning circuit. It shall also include the "non-operation state").

FIG. 3 shows an example of a tablet of the coordinate input device using the above-mentioned input pen 10. In FIG.
Is a position detector, 30 is a selection circuit, 40 is a connection switching circuit,
Reference numeral 50 is a transmission circuit, 60 is a reception circuit, and 70 is a processing device.

The position detector 20 includes a plurality of, for example, 48 loop coils 21-1 and 21 having conductors parallel to each other.
-21, ..., 21-48 are arranged in parallel in the direction of arrow a in the figure (hereinafter referred to as the position detection direction). Also,
The loop coils 21-1 to 21-48 are arranged so as to be parallel to each other and overlap each other. Although each loop coil 21-1 to 21-48 has one turn here, it may have a plurality of turns as necessary.

The position detecting section 20 is formed into a plurality of loop coils by connecting a large number of parallel conductors formed by, for example, etching a known printed circuit board with jumper wires or the like. Can be used.

The selection circuit 30 sequentially selects one loop coil from the plurality of loop coils 21-1 to 21-48, and the loop coils 21-1 to 21-4.
One end of 8 is connected to one terminal group 31 respectively,
The other end is connected to each of the other terminal groups 32. The selection contact 33 corresponding to the terminal group 31 and the selection contact 34 corresponding to the terminal group 32 are interlocked with each other and operate based on information from the processing device 70 to select one loop coil.

The selection circuit 30 can be realized by combining a number of well-known multiplexers.

The connection switching circuit 40 alternately connects one loop coil selected by the selection circuit 30 to the transmission circuit 50 and the reception circuit 60, and the selection contacts 33 and 34 of the selection circuit 30 are selected. Contacts 41 and 42
Respectively connected to. The two output terminals of the transmission circuit 50 are connected to the terminals 43 and 45, and the two input terminals of the reception circuit 60 are connected to the terminals 44 and 46. The selection contact 41 corresponding to the terminals 43 and 44 and the selection contact 42 corresponding to the terminals 45 and 46 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 40 is also realized by a known multiplexer.

FIG. 4 shows details of the transmission circuit 50 and the reception circuit 60. In the figure, 51 is an oscillator, 5
Reference numeral 2 is a frequency divider, 53 and 54 are NAND gates, 55 is an exclusive OR (EXOR) gate, and 56 is a drive circuit, which constitute the transmission circuit 50. Further, 61 is an amplifier, 62 and 63 are phase detectors, and 64 and 65 are low-pass filters (LPF), and these constitute the receiving circuit 60.

The processing device 70 controls switching of each loop coil based on an output of the transmission / reception switching signal and the output of the receiving circuit 60, which will be described later, and calculates a designated coordinate value.

Next, the operation will be described. First, the electric wave is transmitted and received between the input pen 10 and the position detecting section 20, and the signal obtained at this time will be described with reference to FIG.

In the transmission circuit 50, a clock pulse of, for example, 4 MHz generated by the oscillator 51 is divided by the frequency divider 52.
Are divided into 1/4, 1/8 and 1/256. Nand gate 5
The pulse signal A of 500 kHz divided by 1/8 is input to one input terminal of 3, and the transmission / reception switching signal B of 15.625 kHz divided by 1/256 is input to the other input terminal.
The output is further inverted by the NAND gate 54 to 32 μse.
It is a signal C that outputs or does not output a pulse signal of 500 kHz for each c.

The signal C is converted into a balanced signal by the drive circuit 56, and further the connection switching circuit 40 and the selection circuit 3 are connected.
It is sent to one loop coil of the position detection unit 20, for example, 21-i via 0. At this time, the loop coil 21
-I generates a radio wave based on the signal C.

At this time, the loop coil 2 of the position detector 20
When the input pen 10 is held in a substantially upright position near 1-i, the radio wave excites the coil 152 of the input pen 10,
The tuning circuit 15 generates an induced voltage D synchronized with the signal C.

Thereafter, in the signal C, there is no signal,
That is, when the loop coil 21-i is switched to the receiving circuit 60 side as the reception period starts, the loop coil 21-i
The radio wave from i immediately disappears, but since there is no circuit change in the tuning circuit 15 of the input pen 10, the induced voltage D gradually attenuates.

On the other hand, the coil 152 generates a radio wave by the current flowing through the tuning circuit 15 based on the induced voltage D.
The radio wave is transmitted through the loop coil 21-
Since i is excited in reverse, an induced voltage E is generated in the loop coil 21-i.

Since the connection switching circuit 40 is switched by the transmission / reception switching signal B, the signal from the loop coil 21-i is taken in only during the transmission suspension period. The received signal E is amplified by the amplifier 61, becomes a signal F, and is further sent to the phase detectors 62 and 63.

The pulse signal A is input as a detection signal to the phase detector 62. At this time, if the phase of the received signal F matches the phase of the pulse signal A, the received signal F is just on the plus side. The inverted signal G is output. The signal G is converted into a flat signal H having a voltage V _{H by} the low-pass filter 64 having a sufficiently low cutoff frequency, and is sent to the processing device 70.

Further, the pulse signal A and a pulse signal having a frequency twice that of the pulse signal A are input to the EXOR gate 55 in the phase detector 63, and the phase signal 63 has the same frequency as the pulse signal A and the phase is delayed by 90 °. A pulse signal A '(not shown) is input as a detection signal. At this time, if the phase of the reception signal F matches the phase of the pulse signal A ′, the signal I that is the reception signal F inverted to the minus side is output.
The signal I is converted into a flat signal J having a voltage -V _{J by} a low-pass filter 65 having a sufficiently low cutoff frequency and sent to a processing device 70.

Here, the switch 15 in the input pen 10
When 1 is off, the phases of the voltage and the current at the resonance frequency of the tuning circuit 15 match, as described above, and therefore the phases of the received signal F and the pulse signal A match. Thus, at this time, the voltage appears only in the signal H, and does not appear in the signal J.

In the input pen 10, the switch 151
If is on, the tuning circuit 1
The current phase at the resonance frequency of 5 lags the voltage phase by a predetermined angle, and thus the phase of the reception signal F also lags the phase of the pulse signal A by a predetermined angle.
Thus, at this time, a voltage appears in both the signals H and J (if the phase delay at this time is 90 °, the voltage appears only in the signal J).

The signals H and J sent to the processing unit 70 are converted into digital signals here, and further,
The arithmetic processing shown in (1) and (2) is performed.

V _X = (V _H ² + V _J ² ) ^1/2 (1) V _θ = tan ⁻¹ (V _J / V _H ) (2) where the voltage V _X is the input pen 10 And loop coil 21-
Indicates a value proportional to the distance to i. The voltage V _θ shows a value proportional to the phase difference between the voltage and the current in the tuning circuit 15 of the input pen 10.

The value of the voltage V _X changes when the loop coil 21-i for transmitting and receiving radio waves to and from the input pen 10 is switched, and the position of the input pen 10 is detected from this as will be described later.

The value of the voltage V _θ is determined by turning on the switch 151.
Since it changes only by turning off, the on / off state of the switch 151 is identified by comparing the voltage V _θ with a predetermined threshold voltage.

Next, the manner of position detection will be described with reference to FIGS.

First, the power of the entire tablet is turned on,
When the measurement is started, the processing device 70 causes the position detection unit 20 to
Among the loop coils 21-1 to 21-48, information for selecting the first loop coil 21-1 is sent to the selection circuit 30, and the loop coil 21-1 is connected to the connection switching circuit 40. The connection switching circuit 40 alternately controls the loop coil 21-1 to switch between the transmission circuit 50 and the reception circuit 60 based on the transmission / reception switching signal B described above.

At this time, the transmitting circuit 50 has a 16 kHz of 500 kHz as shown in FIG. 6 (a) during the transmitting period of 32 μsec.
The individual pulse signals are sent to the loop coil 21-1 (in FIG. 5, only eight of them are shown for the convenience of the drawing).

As shown in FIG. 6 (b), the switching between the transmission and the reception is performed for one loop coil, here 7 for 21-1.
Repeated several times. The repeating period of 7 times of transmission and reception corresponds to the selection period (448 μsec) of one loop coil.

At the outputs of the phase detectors 62 and 63 of the receiving circuit 60, induced voltages are obtained for each loop coil every seven reception periods. These induced voltages are, as described above, low-pass filters. 64,65 averaged, processing device 7
Sent to 0. The two induced voltages are converted into a detection voltage V _X1 proportional to the distance between the input pen 10 and the loop coil 21-1 by the above-described arithmetic processing in the processing device 70,
It is temporarily stored.

Next, the processing device 70 includes the loop coil 21-2.
Is sent to the selection circuit 30, the loop coil 21-2 is connected to the connection switching circuit 40, and the detection voltage V _X2 proportional to the distance between the input pen 10 and the loop coil 21-2.
Is obtained and stored, and thereafter, similarly, the loop coil 21-
3 to 21-48 are sequentially connected to the connection switching circuit 40, and
Detection voltages V _{X1 to} V _X48 proportional to the distance between each loop coil and the input pen 10 as shown in (c) (however, FIG. 6C).
Shows only some of them. ) Is remembered.

As shown in FIG. 7, the actual detection voltage is generated only in several loop coils before and after the position (xp) where the input pen 10 is placed as the center.

When the stored voltage value of the detected voltage is equal to or higher than a certain detection level, the processing device 70 calculates a coordinate value representing the position of the input pen 10 from these voltage values as will be described later, and calculates the coordinate value. It is transferred to a storage unit (not shown).

When the first position detection is completed in this way, the processing device 70 causes the loop coils 21-1 and 21-2 to
Among the 1 to 48, the loop circuit having the maximum detected voltage is centered and a constant value before and after the loop coil, for example, information for selecting only 10 loop coils is sent to the selection circuit 30,
The detection voltage is obtained in the same manner as described above, the position is detected, the obtained coordinate value is transferred to the storage unit, and the value is updated.

On the other hand, the processing device 70 uses the detection voltages V _X1
˜V _X48 , a detection voltage V _θ proportional to the phase difference between the voltage and the current in the tuning circuit 15 of the input pen 10 is calculated, and the detection voltage V _θ is constantly compared with a predetermined threshold voltage to switch the input pen 10. Identifies 151 on / off.

Here, the processing device 70 causes the cursor 151 to be displayed at a corresponding coordinate position on a display device (not shown) as a temporary coordinate value when the switch 151 is not operated, that is, when the switch 151 is off. The coordinate value when the 151 is operated, that is, when it is turned on, can be displayed as the coordinate value to be input, for example, the handwriting can be displayed at the corresponding coordinate position on the display device. Therefore, when the switch 151 is not operated, the input pen is operated. The position to be input can be specified by the switch 151 while confirming the position of 10.

FIG. 8 shows the timing of the second and subsequent detection operations in the processing device 70. In the figure, the level check is to check whether the maximum value of the detection voltage has reached the detection level and which loop coil has the maximum detection voltage, and reach the detection level. If not, stop the coordinate calculation,
Further, the center of the loop coil selected in the next detection operation is set.

As one of the calculation methods for obtaining the coordinate value xp, there is a method for approximating the waveforms of the detected voltages V _{X1 to} V _X48 near the maximum value by an appropriate function and obtaining the coordinates of the maximum value of the function.

For example, in FIG. 6C, when the maximum detection voltage V _X3 and the detection voltages V _X2 and V _X4 on both sides thereof are approximated by a quadratic function, they can be calculated as follows (however, , The coordinate values of the center positions of the loop coils 21-1 to 21-48 are x1 to x48, and the interval between them is Δx.). First, from each of the voltage and the coordinate _{values, V X2 = a (x2 -xp} ) 2 + b ...... (3) V X3 = a (x3 -xp) 2 + b ...... (4) V X4 = a (x4 -xp) ² + b ... (5) Here, a and b are constants (a <0). Further, x3 −x2 = Δx (6) x4 −x2 = 2Δx (7) (6), (7) (4), (5) and rearranging are substituted into equation, xp = x2 + Δx / 2 {(3V X2 -4V X3 + V X4) / (V X2 -2V X3 + V X4) ｝ …… (8)

Therefore, from the respective detection voltages V _{X1 to} V _X48 , the maximum detection voltage and the detection voltages before and after it, which are obtained during the level check, are extracted, and these and the maximum detection voltage are obtained. Further, the coordinate value xp of the input pen 10 can be calculated by performing the calculation corresponding to the above equation (8) from the coordinate value (known) of the loop coil immediately before the loop coil.

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

FIG. 9 shows another example of the tablet of the coordinate input device using the above-mentioned input pen 10, and here shows an example in which the coordinate value of the designated position in the X and Y directions can be detected. That is, in the figure, 81 and 82 are X-direction and Y-direction position detection units, 83 and 84 are X-direction and Y-direction selection circuits, and 85 and 86 are X-direction and Y-direction connection switching circuits, respectively. Position detection unit 20, selection circuit 30,
The position detection unit 8 has the same configuration as the connection switching circuit 40 (however, the details are omitted for convenience of the drawing).
The loop coils of Nos. 1 and 82 are superposed on each other so as to be orthogonal to the X direction and the Y direction. A processing device 87 is the same as the processing device 70 described above except that the position detection in the X direction and the position detection in the Y direction are alternately performed, and the second and subsequent coordinate detections in the processing device 87 are performed. The operation timing is shown in FIG. The configurations of the transmission circuit 50 and the reception circuit 60 may be the same as those of the tablet described above.

The tablet of the coordinate input device described so far is the most preferable example of those that can use the position indicator of the present invention, and the present invention is not limited to this. For example, a loop coil for generating radio waves and The loop coil for detecting the radio wave may be separately provided, and in this case, the radio wave may be always generated.

[0059]

As described above, according to the first aspect of the present invention, the first tuning circuit which is normally closed is provided.
And a second state consisting of a second tuning circuit connected to the first tuning circuit by an operator's operation, and arbitrarily and alternatively selected by the operator's operation. It is configured to be tuned to a radio wave transmitted from the tablet in any of the first and second states, and due to the tuning, the position indicator together with the position information is set to the first position. Since the state 1 or the second state is configured to be notified by different radio waves transmitted to the tablet, coordinate input can be performed by generating and detecting radio waves on the coordinate input device side. In addition to not requiring a connection cable with the device or a battery for driving the oscillator, it does not need to have two independent tuning circuits and can be operated regardless of whether or not the operator's operation is performed. Information can be notified together with the state corresponding to the operation, for example, whether or not the position indicator is pressed against the tablet regardless of whether the position indicator is pressed against the tablet, and the pointed position is displayed on the display screen. It is possible to input while confirming by displaying on.

Further, according to claim 2 of the present invention, the first tuning circuit comprises at least one coil and a capacitor, and the second tuning circuit is provided with the first tuning circuit via a switch operated by an operator. Since the tuning frequency of the tuning circuit and a predetermined element that makes the tuning frequency different are connected to the first tuning circuit, there is no need to provide two independent tuning circuits, and a simple circuit configuration is used. The position information can be accurately notified to the coordinate input device side together with the state corresponding to the operation of the operator.

Further, according to claim 3 of the present invention, in any of the first and second states, it is constituted so as to be tuned to the radio wave of the same frequency transmitted from the tablet, and the position information and The position indicator is in the first state or the second state.
Since it is configured to notify which of the above states is being transmitted by radio waves having different phases transmitted to the tablet, position information can be operated by the operator only by transmitting radio waves of one type of frequency from the tablet. It is possible to accurately notify the coordinate input device side together with the state corresponding to.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a position indicator in a coordinate input device of the present invention.

FIG. 2 is a configuration diagram of a tuning circuit of a position indicator.

FIG. 3 is a configuration diagram showing an example of a tablet of a coordinate input device using the position indicator of the present invention.

FIG. 4 is a detailed configuration diagram of a transmission circuit and a reception circuit in the tablet.

5 is a waveform diagram of each part of FIG.

FIG. 6 is a timing diagram showing a basic detection operation in the tablet processing device.

FIG. 7 is a diagram showing a detection voltage obtained from each loop coil during a first detection operation.

FIG. 8 is a timing diagram showing the second and subsequent detection operations.

FIG. 9 is a configuration diagram showing another example of the tablet of the coordinate input device using the position indicator of the present invention.

10 is a view similar to FIG. 8 on the tablet of FIG. 9.

[Explanation of symbols]

10 ... Input pen, 15 ... Tuning circuit, 151 ... Switch, 15
2… Coil, 153, 154… Capacitor, 155… Variable capacitor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Satoru Senda Satoshi Senda 2-510 Toyonodai, Toyonedai, Otone-machi, Kita-Saitama-gun, Saitama Prefecture Wacom Co., Ltd. (56) Reference JP-A-54-43619 (JP, A)

Claims (3)

[Claims] 1. A position indicator used in a coordinate input device, wherein the position indicator comprises a first state of a first tuning circuit that is constantly closed, and the position indicator is operated by an operator. A second state composed of a second tuning circuit connected to the first tuning circuit and configured to be arbitrarily and alternatively selectable by an operation of the operator, and the position indicator is In any of the first or second state, the position indicator is configured to be tuned to the radio wave transmitted from the tablet, and the position indicator causes the position indicator together with the position information due to the tuning. The position indicator in the coordinate input device, wherein the position indicator is configured to notify whether the state is the first state or the second state by different radio waves transmitted to the tablet. 2. The first tuning circuit comprises at least one coil and a capacitor, and the second tuning circuit is a tuning frequency of the first tuning circuit and its tuning frequency via a switch operated by an operator. 2. The position pointing device according to claim 1, wherein a predetermined element for making the difference is connected to the first tuning circuit. 3. In any one of the first and second states, the position indicator is configured to be tuned to a radio wave of the same frequency transmitted from the tablet, and the position indicator together with the position information is in the first state. Or in the second state,
The notification is provided by radio waves having different phases transmitted to the tablet.
Alternatively, the position indicator described in 2.