JPH02161511A - Position indicator - Google Patents

Abstract

PURPOSE:To eliminate the need for a battery and a cable and to improve operability for specifying a position by forming a frequency tuning circuit by passive elements such as a coil and a capacitor. CONSTITUTION:A tuning circuit 15 consisting of only passive elements such as a coil 152 and a capacitor 153 is included in a light pen 10 to be a position indicator. At the time of using the pen 10, the coil 152 in the circuit 15 is excited by a specific frequency signal generated from a tablet, an induced voltage is generated, a radio wave generated from the circuit 15 is detected by the tablet in a position detector, and the coordinate value on the tablet is detected by the pen 10 eliminating the use of a battery and a cable. Consequently, the position detector improved at its operability can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a position indicator for a position detection device, and more specifically, to a position indicator that does not require cables or batteries.

(Prior Art) A conventional position indicator of this type has an excitation coil provided at one end of the casing, and current is supplied to the excitation coil to generate electromagnetic waves, which locally touch the tablet of the position detection device. By applying an electromagnetic variable to the sensor, or by providing a detection coil at one end of the housing, the detection coil detects electromagnetic variables sequentially and locally generated from the tablet of the position detection device at a predetermined timing. By this,
There was one that allowed you to specify any location.

(Problem to be Solved by the Invention) However, in the position indicator, there is a cable for detecting an electromagnetic variable from a cable for supplying current to an excitation coil or a detection coil, or a cable for supplying current to an excitation coil. The problem was that it required several batteries, and the operability during position specification work was poor.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide a position indicator that does not require cables or batteries and can accurately specify a position.

(Means for Solving the Problems) In order to achieve the above object, the present invention proposes a position indicator that includes only passive elements such as coils and capacitors, and is equipped with a tuning circuit that is tuned to a specific frequency.

(Function) According to the present invention, it is placed on the tablet of the position detection device,
When the tablet emits radio waves having a specific frequency, a coil in the tuned circuit is excited based on the radio waves, and an induced voltage is generated. The induced voltage causes a current to flow in the tuned circuit, and this current causes a coil in the tuned circuit to generate radio waves, which are detected by the tablet of the position detection device, thereby determining the coordinate values on the tablet. It will be done.

(Embodiment) Fig. 1 shows an embodiment of the position indicator of the present invention, for example, a hand-powered pen 10, in which a ballpoint pen, etc. a core body 12, a ferrite core 13 having a through hole capable of slidably accommodating the core body 12, a coil spring 14, and a switch 151. A tuning circuit 15 consisting of a coil 152[deg.] capacitors 153 and 154 and a variable capacitor 155 wound around a ferrite core 13 is integrated and built in, and a cap 16 is attached to the rear end.

The capacitor 153 and the variable capacitor 155 are connected in parallel with each other as shown in FIG. 2, and both ends thereof are connected to the coil 152, forming a well-known parallel resonant circuit. In addition, the coil 152° and the capacitor 153
The numerical values of the variable capacitor 155 and the variable capacitor 155 are selected to resonate (synchronize) with the frequency of radio waves transmitted from each loop coil of the position detecting section, which will be described later.

On the other hand, a capacitor 154 is connected to both ends of the coil 152 via a switch 151, and when the switch 151 is turned on, it acts to delay the phase of the current in the parallel resonant circuit described above by a predetermined angle.

Note that the switch 151 is configured such that when the tip of the core 12 is pushed into the pen barrel 11 by pressing the tip of the core 12 against the input surface (not shown) of the position detection section, the rear end of the core 12 is inserted through the coil spring 14. It is suppressed and turned on.

FIG. 3 shows an example of a tablet of a position detection device using the input pen 10 described above. In the figure, 20 is a position detection section, 30 is a selection circuit, 40 is a connection switching circuit, 50 is a transmission circuit, and 60 is a The receiving circuit 70 is a processing device.

The position detection unit 20 includes a plurality of, for example, 48, loop coils 21-1, 21-2, and 21-2, each having conductors parallel to each other. ...
...21-48 are arranged in parallel in the direction of arrow A (hereinafter referred to as position detection direction) in the figure. Further, the loop coils 21-1 to 21-48 are arranged parallel to each other and overlapping each other. In addition, although each of the loop coils 21-1 to 21-48 is configured with one turn here, it may be configured with multiple turns as necessary.

As the position detection unit 20, a plurality of loop coils formed by connecting a large number of parallel conductors formed by etching a well-known printed circuit board with jumper wires or the like may be used. Can be done.

The selection circuit 30 selects the plurality of loop coils 21-1 to 21-2.
The - loop coils 1-48 are sequentially selected, and one end of the loop coils 21-1 to 21-48 is -
, and the other end thereof is connected to another terminal group 32, respectively. Selection contact 33 corresponding to terminal group 31 and selection contact 3 corresponding to terminal group 32
4 are interlocked with each other and operate based on information from the processing device 70 to select the negative loop coil.

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

The connection switching circuit 40 connects the loop coil selected by the selection circuit 30 to the transmitting circuit 5o and the receiving circuit 60.
The selection contacts 33 and 34 of the selection circuit 30 are connected to the selection contacts 41 and 42, respectively. Further, the two output terminals of the transmitting circuit 50 are connected to the terminal 43.45, and the two input terminals of the receiving circuit 60 are connected to the terminal 44.46. Selection contact 41 and terminal 45°4 corresponding to the terminals 43 and 44
The selection contacts 42 corresponding to 6 are interlocked with each other and operate based on a transmission/reception switching signal, which will be described later, to switch between transmission and reception.

Note that the connection switching circuit 40 is also realized by a well-known multiplexer.

FIG. 4 shows details of the transmitting circuit 50 and receiving circuit 60. In the figure, 51 is an oscillator, 52 is a frequency divider, 53 and 54 are Nant gates, 55 is an exclusive OR (EXOR) gate, and 56 is a drive circuit, which constitute a transmitting circuit 50. In addition, 61 is an amplifier, 6
2.63 is a phase detector, 64.65 is a low-pass filter (L
P F), and these constitute the receiving circuit 60.

The processing device 70 includes a transmission/reception switching signal and a receiving circuit 6, which will be described later.
Based on the output of 0, switching of each loop coil is controlled and specified coordinate values are calculated.

Next, the operation will be described. First, the manner in which radio waves are transmitted and received between the input pen 10 and the position detection section 20, and the signals obtained at this time will be described with reference to FIG.

In the transmitting circuit 50, the clock pulse of, for example, 4 MHz generated by the oscillator 51 is divided into l/4 by the frequency divider 52,
The frequency is divided into 1/8 and 1/25B. Nantes Gate 5
One input terminal of 3 has 500kHz divided by l18.
z pulse signal A is input, and 17 is input to the other input terminal.
A transmission/reception switching signal B of 15.625kHz frequency-divided by 25B is input, and its output is further inverted by a Nant gate 54 to become a signal C that outputs or does not output a 500kHz pulse signal every 32μsec.

The signal C is converted into a balanced signal by the drive circuit 56, and is further sent to the - loop coil of the position detection section 20, for example 21-1, via the connection switching circuit 40 and the selection circuit 30. The loop coil 21-1 generates radio waves based on the signal C.

At this time, if the input pen 10 is held in a substantially upright state near the loop coil 21-1 of the position detection section 20, the waveform excites the coil 152 of the input pen 10, and the tuned circuit 15 An induced voltage synchronized with the signal C is generated.

Thereafter, when the loop coil 21-1 is switched to the receiving circuit 60 side as the signal C enters a no-signal period, that is, the receiving period, the radio wave from the loop coil 21-1 immediately disappears, but the input vent 10 Since there is no circuit change in the tuned circuit 15, the induced voltage gradually attenuates.

On the other hand, the coil 152 generates radio waves by the current flowing through the tuned circuit 15 based on the induced voltage.

The radio waves are transmitted to the loop coil 21- connected to the receiving circuit 60.
1 is reversely excited, an induced voltage E is generated in the loop coil 21-1.

Since the connection switching circuit 40 is switched by the transmission/reception switching signal B, the loop coil 2 is switched only during the transmission stop period.
Take in the signal from 1-1. The received signal E is sent to the amplifier 6
1 and becomes a signal F, which is further amplified by phase detector 6
Sent on 2.63.

The pulse signal A is input as a detection signal to the phase detector 62, and at this time, if the phase of the received signal F matches the phase of the pulse signal A, the received signal F has just been inverted to the positive side. Outputs signal G. The signal G is converted into a flat signal H of voltage v11 by a low-pass filter 64 whose cut-off frequency is sufficiently low, and sent to the processing device 70.

The phase detector 63 still receives a pulse signal A that has the same frequency as the pulse signal A and is delayed in phase by 90@, which is created by inputting the pulse signal A and a pulse signal with twice the frequency to the EXOR gate 55. ' (not shown) is input as a detection signal.

At this time, if the phase of the received signal F matches the phase of the pulse signal, a signal I, which is exactly the negative side of the received signal F, is output. That signal! is converted into a flat signal J of voltage VJ by a low-pass filter 65 whose cut-off frequency is sufficiently low, and sent to a processing device 70.

Here, when the switch 151 at the input vent 10 is off, the phases of the voltage and current at the resonant frequency of the tuned circuit 15 match as described above, and therefore, the received signal F and the pulse signal A are in phase. The phases match. At this time, a voltage appears only in the signal H, and no voltage appears in the signal J.

Furthermore, when the switch 151 in the input vent 10 is on, the phase of the current at the resonant frequency of the tuned circuit 15 is delayed by a predetermined angle with respect to the phase of the voltage, as described above. The phase is also pulse signal A
is delayed by a predetermined angle with respect to the phase of . At this time, a voltage appears in both signals H and J (if the phase delay at this time is 90'', a voltage appears only in signal J).

The signals H and J sent to the processing device 70 are here converted into digital signals, and further expressed by the following equation (1),
The calculation process shown in (2) is performed.

v − (vl12 + v 2) 112 ...
(1)X''V = tan (V/Vll)
・'・”'(2) θ
j Here, the voltage Vx is between the input vent 10 and the loop coil 21-
It shows a value proportional to the distance from 1. Also, the voltage V. represents a value proportional to the phase difference between voltage and current in the tuning circuit 15 of the input vent 10.

The value of the voltage (1) 8 changes when the loop coil 21-1 that transmits and receives radio waves to and from the input valve 10 is switched, and the position of the input valve 10 is detected from this as will be described later.

The voltage ■. Since the value of V changes only depending on whether the switch 151 is turned on or off, the voltage V. By comparing φ with a predetermined threshold voltage, on/off of the switch 151 is identified.

Next, the state of position detection will be explained according to FIGS. 6 to 8.

First, when the entire tablet is powered on and enters the measurement start state, the processing device 70 selects the first loop coil 2 of the loop coils 21-1 to 21-48 of the position detection unit 20.
Information for selecting 1-1 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 controls switching of the loop coil 21-1 alternately to 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 sends 16 pulse signals of 500 kHz as shown in FIG. 6(a) to the loop coil 21-1 during a transmission period of 32 μsec (note that in FIG. 5, for convenience of drawing, , only eight of which are shown).

The switching between transmission and reception is as shown in FIG. 6(b).
loop coil, here repeated seven times for 21-1. This seven-time transmission and reception repetition period corresponds to the - loop coil selection period (448 μsec).

At the output of the phase detectors 62 and 63 of the receiving circuit 60, induced voltages are obtained for the - loop coil every seven reception periods, but these induced voltages , 65 and sent to the processing device 70. The two induced voltages are converted by the processing device 70 into a detected voltage Vx which is proportional to the distance between the input valve 10 and the loop coil 21-1 and stored.

Next, the processing device 70 sends information for selecting the loop coil 21-2 to the selection circuit 30, connects the loop coil 21-2 to the connection switching circuit 40, and adjusts the distance between the input vent 10 and the loop coil 21-2. A proportional detection voltage Vx2 is obtained and stored, and thereafter the loop coils 21-3 to 21-
48 are sequentially connected to the connection switching circuit 40, and the detection voltage V-V is proportional to the distance from the input vent 10 for each loop coil as shown in FIG. 6(C). Xi
X4B shows only a part of it. ).

As shown in FIG. 7, the actual detected voltage is centered around the position (xp) where the input vent 10 is placed, and is generated only in several loop coils before and after the position (xp).

When the voltage value of the stored detection voltage is above 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 described later,
This is transferred to a storage unit (not shown).

When the first position detection is completed in this way, the processing device 70 selects a certain number of loop coils before and after the loop coil from which the maximum detection voltage has been obtained among the loop coils 21-1 to 21-48, for example. Information for selecting only the 10 loop coils is sent to the selection circuit 30, a detection voltage is obtained in the same manner as described above, position detection is performed, and the obtained coordinate values are transferred to the storage section and the values are updated. .

On the other hand, the processing device 70 calculates a detection voltage V which is proportional to the phase difference between voltage and current in the tuning circuit 15 of the input pen 10, as well as the detection voltages Vx□ to V, and always sets the detection voltage V to a predetermined threshold value. Compared with the θ voltage, the ON/OFF state of the switch 151 of the input pen 10 is
Identifies off.

Here, the processing device 70 displays the coordinate values when the switch 151 is not operated, that is, when the switch 151 is off, as temporary coordinate values, for example, displays a cursor at the corresponding coordinate position on a display device (not shown), and also displays a cursor at the corresponding coordinate position on a display device (not shown). was done,
That is, the coordinate value when it is on can be used as a coordinate value to be input, and the handwriting can be displayed at the corresponding coordinate position on a display device, for example. Therefore, the position of the input pen 10 can be confirmed when the switch 151 is not operated. At the same time, the position to be input can be specified by the switch 151.

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

As one of the calculation methods for determining the coordinate value xp, the detection voltage v
-■ Waveform near the maximum value of XI X4
There is a method of approximating with a g function and finding the coordinates of the maximum value of that function.

For example, in FIG. 6(e), the maximum detection voltage Vx3
By approximating the detection voltages Vx□ and Vx4 on both sides thereof by a quadratic function, it can be calculated as follows (however, the coordinate values of the center positions of each loop coil 21-1 to 21-48 are -x48, and the interval is ΔX.)
. First, from each voltage and coordinate value, Vx2-a(x2-xp) +b -(3
)Vx3-a(x3-xp) 10b ””
”(4) Vx4-a (x4-xp) +b
---(5). Here, a and b are constants (
ago).

Also, x3 −x2 −ΔX −
・−・(Q)x4−x2 =2ΔX
−・−・・(7). (6), (7) to (4),
Substituting into equation (,5) and rearranging, xp mx”l+ΔX/2((3Vx2-4vx3+
vx4) / (Vx2-2 Vx3+ Vx4) 1
・・・・・・(8)

Therefore, from each detection voltage V −V, the above Xi
X4g Extract the maximum detected voltage obtained during the bell check and the detected voltages before and after it, and extract these and the coordinate values of the loop coil immediately before the loop coil from which the maximum detected voltage was obtained (known) The coordinate value xp of the input pen 10 can be calculated by performing an operation corresponding to the above-mentioned equation (8).

Note that the number of loop coils and the arrangement thereof in the embodiments are merely examples, and it goes without saying that the present invention is not limited thereto.

FIG. 9 shows another example of the tuning circuit of the input pen 10 of the present invention. Here, an example is shown in which the position is detected only when the core body 12 is pushed into the pen shaft 11. show.

That is, the switch 151 is connected between the parallel circuit consisting of capacitors 153 and 155 and the coil 152, and when the core 12 is not pushed into the pen barrel 11, the switch 151 is turned off, and therefore the tuning circuit is turned off. Furthermore, when the core 12 is pushed into the pen barrel 11, the switch 151 is turned on, thus forming a tuning circuit and detecting the position.

When using an input pen using this tuning circuit, all detected coordinate values are used as input values.

FIG. 10 shows another example of the tablet of the position detection device using the input pen 10 described above, and here, an example is shown in which the coordinate values of a specified position in the X direction and the Y direction can be detected. That is, in the figure, 81 and 82 are position detection units in the X direction and Y direction, 83 and 84 are selection circuits in the X direction and Y direction, and 85
and 86 are X-direction and Y-direction connection switching circuits, which have the same configurations as the position detection unit 20, selection circuit 30, and connection switching circuit 40 described above (however, due to the drawing, the details are omitted). (omitted), the respective loop coils of the position detection units 81 and 82 are superimposed on each other so as to be orthogonal to the X direction and the Y direction, respectively. Also,
87 is a processing device, which is the same as the processing device 7 described above except that the position detection in the X direction and the Y direction is performed alternately.
0, and the timing of the second and subsequent coordinate detection operations in the processing device 87 is shown in FIG. Also,
Transmission circuit 50. The configuration of the receiving circuit 60 may be the same as that of the tablet described above.

Note that the tablet of the position detection device described so far is the most preferable example of the device that can use the position indicator of the present invention, and is not limited thereto.For example, a loop coil that generates radio waves and a tablet that detects radio waves are used. The loop coil may be provided separately, and in this case, the radio waves may be generated at all times.

(Effects of the Invention) As explained above, according to the present invention, since it is comprised only of passive elements such as coils and capacitors and is equipped with a tuning circuit that tunes to a specific frequency, the specific frequency can be detected from the tablet of the position detection device. When a radio wave with a specific frequency is transmitted, this is received by the coil of the tuned circuit and an induced voltage is generated.Based on the induced voltage, the coil of the tuned circuit transmits a radio wave with a specific frequency, thereby It is possible to give an electromagnetic variable to the tablet of the position detection device according to its position, that is, it is possible to specify the position accurately, and there is no need for a cable between the tablet of the position detection device, and It is only necessary to provide a tuning circuit consisting of passive elements such as coils and capacitors, and there is no need for heavy parts such as batteries or magnets, so there are advantages such as the ability to realize a position indicator with extremely excellent operability. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the position indicator of the present invention;
Fig. 2 is a block diagram of a tuning circuit of a position indicator, Fig. 3 is a block diagram showing an example of a tablet of a position detecting device using the position indicator of the present invention, and Fig. 4 is a block diagram of a transmitting circuit and a receiving circuit in the tablet. A detailed configuration diagram, FIG. 5 is a waveform diagram of each part in FIG. A diagram showing the detection voltage obtained from each loop coil during the first detection operation, FIG. 8 is a timing diagram showing the second and subsequent detection operations, and FIG. 9 is a tuning circuit of the position indicator of the present invention. FIG. 10 is a configuration diagram showing another example of a tablet of a position detection device using the position indicator of the present invention, and FIG. 11 is similar to FIG. 8 in the tablet of FIG. 10. This is a diagram. 10... Input pen, 15... Tuning circuit, 152...
・Coil, 153... Capacitor.

Claims (4)

[Claims] (1) Consists only of passive elements such as coils and capacitors,
A position indicator characterized by being equipped with a tuning circuit that tunes to a specific frequency. (2) The position indicator according to claim 1, characterized in that a switch for opening and closing the entire circuit is provided in the tuning circuit. (3) A patent claim comprising a pen-shaped housing and a core body movably housed in the housing in the axial direction, and a switch arranged to open and close based on the movement of the core body. The position indicator according to item 2 of the range. (4) The position indicator according to claim 1, wherein the phase of the voltage and current for a specific frequency of the tuned circuit is changed based on the operation of a switch or the like.