JPH04182816A - Wireless coordinate reader - Google Patents

Abstract

PURPOSE:To decide the state of a switch provided on a coordinate indicator with wireless by deciding the point of transition from the OFF state to the ON state of the switch of the coordinate indicator from an amplitude variation and a phase shift. CONSTITUTION:A control circuit 12 scans an exciting line group 1 and a detecting line group 2 repeatedly. When the amplitude of an inducing signal 104, i.e., the output 105 of an amplitude detecting circuit 8 is maximum in single- time scanning, it is stored in an amplitude storage means 10. The phase obtained from the signal 104, i.e., the output 106 of a phase detecting circuit 9 is stored in a phase storage means 11. The outputs 105 and 106 obtained by next-time scanning in the same conditions are compared to obtain the variation directions of the amplitude and the phase of the signal 104. The outputs 105 and 106 are stored in the means 10 and 11 similarly for comparison in next-time scanning. The circuit 12 repeats the processes and the circuits 9 and 8 detects the phase and amplitude to decide whether the switch is ON or OFF from the directions of the phase shift and amplitude variation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coordinate reading device for inputting two coordinates to a column device such as a computer. This relates to a wireless coordinate reading device that does not require connection.

[Summary of the invention]

A wireless coordinate reading device that determines a transition point from an off state to an on state of a switch of a coordinate indicator based on a change in amplitude and a change in phase of a guidance signal.

[Prior art] Conventionally, the excitation line group and the detection line group laid in the coordinate reading section! In order to detect the state of a switch provided in a coordinate indicator in a coordinate reading device in which magnetic coupling is mediated by a resonant circuit made up of a coil provided in the coordinate indicator and a first capacitor, the state of the switch provided in the coordinate indicator is detected by turning the switch on/off. By connecting/disconnecting the second capacitor in parallel with the resonant circuit and changing the resonant frequency of the resonant circuit, the phase of the induced signal obtained in the detection line group is changed, and the switch state is determined from the amount of change in the phase. There is a method.

For example, when a second capacitor is connected in parallel to a resonant circuit by turning on a switch, the resonant frequency of the resonant circuit changes to a lower direction, and the phase of the induced signal changes to a delayed direction accordingly. . For this reason, the delay in the phase of the induction signal with respect to the phase of the excitation signal is detected, and the amount of delay is compared with a certain threshold value to determine the switch state.

[Problems to be Solved by the Invention] Generally, in this type of coordinate reading device, an electromagnetic shielding member such as a metal plate is placed below the coordinate reading section to block unnecessary noise from the outside. There are many things.

However, in this case, as the distance between the coordinate indicator and the tm shielding member changes, the inductance of the coil that constitutes the resonant circuit of the coordinate indicator changes, so the resonant frequency of the resonant circuit changes, and as a result, the phase of the induced signal changes. affect. For example, when the coordinate indicator moves away from the coordinate reading unit, the inductance of the coil increases, the resonance frequency of the resonant circuit decreases, and the phase of the guidance signal changes to become more delayed.

For this reason, in the conventional technology, when the coordinate indicator moves away from the coordinate reading section, the amount of delay in the phase of the guidance signal exceeds the threshold for determining the switch state, and it is mistakenly assumed that the switch is in the on state. There was a risk of being judged. In addition, in order to avoid erroneous judgments, the threshold value for switch state judgment must be set to a value that is sufficiently large relative to the phase delay of the guidance signal that occurs due to the movement of the coordinate indicator. If the phase range is small, for example, if you have multiple switches and try to set multiple thresholds to determine these states, there will be no margin for opening the thresholds, and the usage environment, changes over time, and individual There is a problem in that phase variations due to differences cannot be absorbed.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a coordinate reading unit in which a plurality of excitation line groups and a plurality of detection line groups are laid in an overlapping manner, a coil, and a first capacitor. a coordinate indicator having a resonant circuit composed of a resonant circuit, and a series circuit comprising at least a switch and a second capacitor connected to the resonant circuit in one circuit or a plurality of circuits in parallel; a second selection circuit that sequentially selects the detection line group; and an excitation circuit that is connected to the first selection circuit and provides the excitation line group with an excitation signal having a frequency near the resonant frequency of the resonant circuit of the coordinate indicator. and an amplitude detection circuit that is connected to the second selection circuit and detects the amplitude of the induced signal guided to the detection line group.
a phase detection circuit that detects the phase of the induction signal with respect to the excitation signal; and an amplitude storage means that stores the output of the amplitude detection circuit;
a phase storage means for storing the output of the phase detection circuit; a difference between the output of the amplitude detection circuit and the information stored in the amplitude storage means; and a difference between the output of the phase detection circuit and the information stored in the phase storage means. A control circuit for determining the state of the switch in the coordinate indicator is provided.

[Operation] In the coordinate reading device configured as described above, when an excitation signal is applied from the excitation circuit to the excitation line group, an induction signal is generated if the excitation line and detection line near where the coordinate indicator is located are selected. arise.

Here, when the coordinate indicator is turned on/off, the second capacitor is connected/cut off, so the resonant frequency of the resonant circuit changes, and the phase of the induced signal generated in the detection line changes. For example, when the second capacitor is connected to H by turning on the switch, the resonant frequency of the resonant circuit changes to a lower direction, and the phase of the induced signal changes to a later direction.

On the other hand, when the coordinate indicator moves away from the coordinate reading section, the inductance of the coil increases, so the resonant frequency of the resonant circuit decreases, and the phase of the induction signal lags behind, similar to when the switch is turned on. Change.

On the other hand, if the resonant frequency of the resonant circuit when the coordinate indicator switch is off is set near the frequency of the excitation signal and approaches the frequency of the excitation signal, in the above example, it is slightly higher than the frequency of the excitation signal. When set, the amplitude of the induced signal changes in the direction of increasing as the switching speed increases.

However, when the coordinate indicator moves away from the coordinate reading section, the degree of iit magnetic coupling between the excitation line and the coil and between the coil and the detection line decreases, so the amplitude of the induction signal changes in the direction of decreasing.

That is, when the coordinate indicator is switched on and when the coordinate indicator is moved in a direction away from the coordinate reading section, the phase change of the guidance signal is similar, but the amplitude change of the guidance signal is opposite.

Therefore, the change in the amplitude of the guided signal is determined from the difference between the output of the amplitude detection circuit and the information stored in the amplitude storage means, and the change in the amplitude of the guided signal is determined from the difference between the output of the phase detection circuit and the information stored in the phase storage means. By obtaining the change in phase, it is possible to determine the switch-like behavior in the coordinate indicator.

[Example] An example of the present invention will be described below with reference to FIG. 1st
Figure A shows a configuration diagram of a coordinate reading device according to the present invention. In the figure, l is an excitation line group, 2 is a detection line group, and 3 is a coordinate reading unit h. Excitation line group 1 and detection line group 2 are arranged at equal intervals and perpendicular to each other, and coordinate reading is performed. It constitutes part 3. 4 is a coordinate indicator having a resonant circuit which will be described later. 5 is an excitation circuit h, excitation signal 10
1 to the excitation line group 1, 66 is a first selection circuit that sequentially selects the excitation line group 1, and 7 is a second selection circuit that sequentially selects the detection line group 2. 6 and 8 are generated in the detection line group. 9 is a phase detection circuit that detects the phase of the guided signal 104. 10 is amplitude storage means for storing the output 105 of the amplitude detection circuit 8;
Reference numeral 1 denotes phase storage means h for storing the output 106 of the phase detection circuit 9, each of which is constituted by a RAM (random access memory). Reference numeral 12 denotes a control circuit h, which is composed of a microprocessor.

FIG. 2 shows a sectional view of the coordinate reading section 3.

In the figure, excitation line group 1 and detection line group 2 are respectively connected to circuit board 3.
An electromagnetic shielding member 33 is placed below the circuit board 31 with a spacer 32 in between.

FIG. 3 shows a circuit included in the coordinate indicator 4 of the first embodiment, in which 40 is a coil, 41 is a first capacitor h, and constitutes an LC resonance circuit. 42 is a switch, and 43 is a second capacitor h, which are connected in series and further connected in parallel to the LC resonance circuit.

FIG. 6 shows a configuration diagram of the excitation circuit 5. In the figure, 50
51 is a waveform shaping circuit, and 51 is an amplifier circuit.

The waveform shaping circuit 50 shapes the rectangular wave excitation clock 100 input from the control circuit 12 and converts it into a sine wave.
The amplifier circuit 51 amplifies this and outputs the excitation signal 101.

In the seventh part, a configuration diagram of the first selection circuit 6 is shown. In the figure, 60 is a decoder, and 61 is a switch element group. The decoder 60 receives the first selection signal 1 input from the control circuit 12.
02, one of the switch elements 61a to 61n of the switch element group 61 is turned on. As a result, the excitation signal 101 inputted from the excitation circuit 5 is supplied to the excitation line corresponding to the turned-on switch element among the excitation lines mx1a to 1n of the excitation line group 1.

The second selection circuit 7 has the same configuration as the first selection circuit 6, and details are not shown. The difference is that the first selection circuit 6
selects the excitation line group 1 according to the first selection signal 102 and supplies the excitation signal 101 to the selected excitation line, whereas the second selection circuit 7 selects the detection line group 1 according to the second selection signal 103. This is the point at which group 2 is selected and the guidance signal 104 generated on the selected detection line is output.

FIG. 8 shows a configuration diagram of the amplitude detection circuit 8. In the figure,
80 is an amplifier circuit, 81 is a detection circuit, 82 is a smoothing circuit, 8
3 is an A/D conversion circuit. The amplitude detection circuit 8 converts the induced signal 104 into an amplification circuit 80, a detection circuit 81, a smoothing circuit 82,
A signal 105 is output by digitizing the amplitude of the induction signal 104 by passing through the A/D conversion circuit 83 in this order.

FIG. 9 shows a configuration diagram of the phase detection circuit 9. In the figure,
90 is an amplifier circuit, 9I is a comparator, 92 is an exclusive OR element, 93 is a resistance element, 94 is a capacitor, and 95 is an A/D conversion circuit. The induced signal 104 is transmitted through the amplifier circuit 90
After being amplified by the comparator 91 and converted into a rectangular wave by the comparator 91, the signal is connected to one input of the exclusive OR element 92.

Excitation clock 1 is connected to the other input of exclusive OR element 92.
00 is connected, and the exclusive OR element 92 outputs a pulse signal representing the phase difference of the induced signal 104 with respect to the excitation clock 100 in terms of pulse width. The resistive element 93 and the capacitor 94 form an integrating circuit, and by integrating the output of the exclusive OR element 92, the phase difference is converted into a voltage signal expressed as a voltage. The A/D conversion circuit 95 outputs a signal 106 obtained by digitizing the voltage signal.

Note that the configurations of the amplitude detection circuit 8 and the phase detection circuit 9 are not the essence of the present invention; they convert the amplitude of the induction signal 104 and the phase difference of the induction signal 104 with respect to the excitation signal 101 into signals that can be processed by the control circuit 12. It's fine if you can. Therefore, the present invention is not limited to this embodiment, and various configurations are possible.

The operation of this embodiment will be explained below. In FIG. 1, the control circuit I2 connects the EjJ magnetic clock oo to the excitation circuit 5.
At the same time, the first selection signal 102 is outputted so that the first selection circuit 6 sequentially selects each excitation line of the excitation line group 1. As a result, the excitation signal 101 is sequentially supplied to the selected excitation line, and the excitation line generates an alternating current magnetic field. On the other hand, while selecting any one excitation line, the control circuit 12
The selection circuit Ia7 outputs the second selection signal 103 so as to sequentially select each detection line of the detection line group 2. The selected detection line is thereby connected to the amplitude detection circuit 8 and the phase detection circuit 9. The control circuit 12 repeatedly performs the above operations. This operation will be called "scanning". Note that the scanning order is not limited to the above example; for example, while any one detection line is selected, the excitation Mi lines may be sequentially selected and this may be repeated.

If the coordinate indicator 4 is not on the coordinate reading section 3, the excitation line group 1 and the horizontal line group 2 are perpendicular to each other, so the AC magnetic field generated in the excitation line group 1 guides the excitation line group 1 to the detection line group 2. No current is generated. - On the other hand, when the coordinate indicator 4 is on the coordinate reading unit 3, when the excitation line and detection line near the coordinate indicator 4 are selected in the above scanning, the excitation Ti1vA and the detection line in the coordinate indicator 4 are tVA coupling occurs between the coil 40 and between the coil 40 and the detection line, and an induced current is generated in the detection line, which is output as an induction signal 104 via the second selection circuit 7.

(ii) The degree of magnetic coupling is correlated with the distance between the excitation line and the detection line and the coordinate indicator 4, and the magnitude of the induced current changes depending on the position of the coordinate indicator 4.

Therefore, by sequentially inputting the amplitude of the guidance signal 104 when scanning the excitation m line and the detection line around the position of the coordinate indicator 4 in the control circuit 12 via the amplitude detection circuit 8, the coordinate indicator 4 Coordinate values indicating the position of can be calculated. Since the method of calculating the coordinates is not the subject matter of the present invention, the details will be omitted, but various methods can be applied, including, for example, the method proposed by the present applicant (Japanese Patent Laid-Open No. 55-96411).

Next, determination of the state of the switch provided in the coordinate indicator 4, which is the gist of the present invention, will be explained.

In the resonant circuit of the coordinate indicator 4 shown in FIG. 3, it is assumed that the resonant frequency is set to be slightly higher than the excitation frequency of the excitation signal 101 when the switch is in the off state. When the switch is turned on here, the second capacitor 43 is connected in parallel to the resonant circuit, so the resonant frequency changes in a lower direction, that is, in a direction closer to the excitation frequency. As a result, in the guidance signal 104 obtained by the above-described scanning, when the switch of the coordinate indicator 4 is in the on state, its amplitude changes in the direction of becoming larger and its phase changes in the direction of delaying, compared to when the switch of the coordinate indicator 4 is in the off state. do. The state of these changes will be further explained with reference to FIG.

In FIG. 10, the horizontal axis is the resonance frequency fr of the coordinate indicator 4.
es, the vertical axis indicates the amplitude V and phase φ of the induced signal 104. Further, fdrν indicates the excitation frequency of the excitation signal 101. As shown in Figure 1O, the amplitude V is the resonant frequency fr
h is largest when eS matches the excitation frequency [drν, and becomes smaller as it deviates from the excitation frequency fdrν,
On the other hand, the phase φ has a characteristic that it monotonically lags as the resonance frequency f res becomes lower.

Here, the resonant frequency f r when the switch is in the off state
Assuming that es is set to fa slightly higher than the excitation frequency fdrν, the amplitude V at this time is Va,
The phase φ is φa. On the other hand, when the switch is turned on and the second capacitor 43 is connected, the resonant frequency f res is lowered, that is, the excitation frequency fdr
If it changes in the direction approaching ν and shifts to rb, the amplitude V becomes Vb and the phase φ becomes φb. That is, from FIG. 10, as the switch turns on, the amplitude ■ changes from Va to vb, and the phase φ changes to φa.
It can be seen that the change occurs in a direction that lags behind φb.

However, as shown in FIG. 2, when an electromagnetic shielding member 33 such as a metal plate is provided below the coordinate reading unit 3, the distance between the coil 40 in the coordinate indicator 4 and the electromagnetic shielding member 3 becomes large. In this case, since the inductance of the coil 40 increases, the resonant frequency of the resonant circuit of the coordinate indicator 4 becomes low, and in this case, the phase of the induction signal 104 changes to be delayed in the same way as when the switch is turned on. For this reason,
It is not possible to determine the state of the switch from only the change in phase. However, in this case, focusing on the amplitude of the induction signal 104, as the distance between the coordinate indicator 4 and the coordinate reading unit 3 increases, the distance between the excitation line group 1 and the coil 40 in the coordinate indicator 4 and between the coil 40 and the Since the degree of electromagnetic coupling with the detection line group 2 decreases, the amplitude of the induced signal 104 changes in the direction of decreasing. These situations will be explained with reference to FIG. 11. In FIG. 11, the horizontal axis indicates the distance #h between the coordinate indicator 4 and the seat reading section 3, and the vertical axis indicates the amplitude V and phase φ of the guidance signal 104. 1st
FIG. 1 shows a characteristic that as the distance increases, the amplitude V gradually decreases and the phase φ gradually changes in the direction of delay. Here, when the coordinate indicator 4 moves from the distance ha to the distance hc, that is, when the coordinate indicator 4 moves from the distance ha to the distance hc,
Considering the case where the amplitude changes in the direction of moving away from the reading section 3 by 2, it can be seen that the amplitude V changes in the direction of decreasing from Va to Vc, and the phase φ changes in the direction of delaying from φa to φC.

As explained above in FIG. 10 and Group 11, the guidance signal 104 is generated when the coordinate indicator 4 is turned on and when it moves away from the coordinate reading section 3.
The changes in phase of are similar while the changes in amplitude are opposite. Therefore, in the present invention, paying attention to this, the state of the switch is determined not only from the phase change but also from the direction of the phase change and the direction of the amplitude change.

Referring back to FIG. 1, a description of the switch state determination will be added. In FIG. 1, the control circuit 12 scans the excitation line group 1 and the detection line group 2 around the coordinate indicator 4 in order to calculate the coordinate values indicated by the coordinate indicator 4, and detects the amplitude of the guidance signal 104 by the amplitude detection circuit 8. are input sequentially via . Here, in order to determine the switch state, the phase of the induced HL signal 104 is inputted in parallel via the phase detection circuit 9, and the excitation line and the detection line which are in a specific positional relationship with the coordinate indicator 4 during the above scanning are input. Each change in amplitude and phase obtained when is selected is detected. Regarding the phase, it is possible to detect the phase if the area around the coordinate indicator 4 is scanned and the guidance signal 104 is generated, but considering the S/N, the phase can be detected when the amplitude of the guidance signal 104 is the largest, that is, the coordinate indication It is preferable that the excitation line and detection line closest to the device 4 are selected. Therefore, while repeatedly scanning the excitation line group 1 and the detection line group 2, the control circuit 12 changes the amplitude of the output 105 when the amplitude of the induction signal 104, that is, the output 105 of the amplitude detection circuit 8 is at the maximum during one scan. The phase of the induced signal 104 obtained at the same time, that is, the output 106 of the phase detection circuit 9 is stored in the storage means 10, respectively, and the magnitudes are compared with the outputs 105 and 106 obtained under the same conditions in the next scan. The direction of change in amplitude and phase of the induced signal 104 is obtained by comparison. After the comparison, output 105 for comparison in the next scan.
and the output 106 are similarly stored in the amplitude storage means 10 and the phase storage means 11.

By repeatedly performing the above processing, the control circuit 12 sequentially detects the direction of change in the amplitude and phase of the guidance signal 104 for each scan, and as described above, changes in the direction in which the phase lags and the direction in which the amplitude increases. When the amount of change exceeds a certain threshold value, it is determined that the switch is turned on. Furthermore, after determining the on state of the switch, if the phase of the induction signal 104 falls below the value at the time of determining the switch on, it is determined that the switch has returned to the off state.

Fig. 4 shows the circuit of the coordinate indicator 4 in the second embodiment, b, whereas the first embodiment was an example of a coordinate indicator with one switch as shown in Fig. 3. , this embodiment shows a case where there are two switches. In Fig. 4, 40 is a coil, and 41 is a first capacitor.
, configure an LC resonant circuit in the same manner as in FIG. 42a
42b is a switch, 43a is a second capacitor h, and the switch 42a and the capacitor 43a and the switch 42b and the capacitor 43b are connected in series and further connected in parallel to the LC resonant circuit. That is, when the switch 42a is turned on, the capacitor 43
When a turns on the switch 42b again, the capacitor 4
3b will be connected in parallel to the resonant circuit. By setting the capacitances of capacitor 43a and capacitor 43b to different values, switch 42a and switch 4
It is possible to make the amount of change in the phase of the induction signal different when 2b is turned on. Therefore, in this case, by setting two threshold values for the amount of phase change in the control circuit 12, it is possible to determine which of the switches 42a and 42b is turned on. Similarly, a series circuit of multiple switches and capacitors is connected to the LC.
It goes without saying that the states of a plurality of switches can be determined by connecting them in parallel to a resonant circuit and setting a plurality of threshold values.

FIG. 5 shows a circuit of the coordinate indicator 4 in the third embodiment. This embodiment shows another embodiment in which the number of switches is two. In FIG. 5, 40 is a coil, 41
is the first capacitor h, which constitutes an LC resonant circuit in the same manner as in FIG. 42a and 42b are switches, 43 is a second
The capacitors 44a and 44b are resistive elements h,
Switch 42a, resistance element 44a and switch 42b
and resistance element 44b are connected in series to form a switch subcircuit. Each switch subcircuit is connected in parallel, and a second capacitor 43 is connected in series to one end, and further connected in parallel to the LC resonant circuit.

That is, when the switch 42a is turned on, the resistance element 44
The series circuit of a and capacitor 43 is also connected to switch 4.
When 2b is turned on, a series circuit including the resistive element 44b and the capacitor 43 is connected in parallel to each resonant circuit. By setting the resistance values of the resistance element 44a and the resistance element 44b to different values, the switch 42a
It is possible to make the amount of change in the phase of the induction signal different when the switch 42b and the switch 42b are turned on. In the second embodiment, multiple capacitors with different capacitances are connected in parallel to the resonant circuit according to the budding switch, and the amount of phase change is varied, whereas in this embodiment, resistive elements with different resistance values are connected in parallel. The first capacitor is connected in series with a second capacitor, which is connected in parallel to a resonant circuit, and the amount of change in phase is made different by j-. Generally, resistive elements with higher precision and a larger number of effective digits than capacitors are commercially available, so this embodiment has the advantage that it is easy to set the amount of phase change.

In this case as well, the switch/7 switch 42a is
It is possible to determine which of the switch 42b and the switch 42b is turned on. Further, by further connecting a plurality of the switch subcircuits in parallel, it is possible to determine the states of a further plurality of switches.

[Effects of the Invention] As explained above, according to the present invention, the electromagnetic coupling between the plurality of excitation line groups laid in the coordinate reading section and the plurality of detection line groups is mediated by the resonance circuit provided in the coordinate indicator. In a coordinate reading device, the second capacitor is connected/disconnected in parallel to the resonant circuit by turning on/off a switch provided in the coordinate indicator, and the resonant frequency of the resonant circuit is changed to obtain induction in the detection line group. Changed the phase and amplitude of the signal. The phase and amplitude are detected by a phase detection circuit and an amplitude detection circuit, respectively, and the control circuit determines the state of the switch from the direction of each change.

Therefore, it was possible to realize a wireless coordinate reading device that can determine the state of a switch provided in a coordinate indicator without connecting the coordinate reading device main body and the coordinate indicator with a signal line.

In particular, is there a metal plate, etc. below the coordinate reading unit? ! When equipped with a magnetic shielding member, the phase of the guidance signal changes due to changes in the distance from the coordinate indicator, which caused problems in determining the switch state with conventional methods, but this invention has been able to eliminate this problem. .

Furthermore, each element that constitutes the resonant circuit of the coordinate indicator and the coordinate reading device? ! The phase of the induction signal when the switch turns on varies due to temperature changes, changes over time, and individual differences in each element that makes up each circuit of the F main body. When setting an absolute threshold value as a standard for switch state determination, an adjustment mechanism was used to match the constants of each circuit to correct this variation, but in the present invention, the standard for switch state determination is It is set relatively each time the switch is turned on, and the amount of change from this standard is compared with a certain threshold value to make a switch judgment, so there is no need for a conventional adjustment mechanism, regardless of the usage environment or age of use. Alternatively, it was possible to realize a wireless coordinate reading device that can always determine the switch state without losing compatibility of the coordinate indicator or the coordinate reading device itself.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of a coordinate reading device according to the present invention;
FIG. 2 is a sectional view of the seat 41i reading section, FIG. 3 is a circuit diagram of the coordinate indicator of the first embodiment, FIG. 4 is a circuit diagram of the coordinate indicator of the second embodiment, and FIG. 5 is a circuit diagram of the coordinate indicator of the second embodiment. A circuit diagram of the coordinate indicator of the third embodiment, Part 6 is an explanatory diagram of the configuration of the excitation circuit, FIG. 7 is an explanatory diagram of the configuration of the selection circuit, FIG. 8 is an explanatory diagram of the configuration of the amplitude detection circuit, and FIG. 9 is an explanatory diagram of the configuration of the phase detection circuit, FIG. 10 is an explanatory diagram of the amplitude and phase of the induction signal when the switch is pressed,
The 11th is an explanatory diagram of the amplitude and phase of the guidance signal with respect to the distance of the coordinate indicator. 1... Excitation line group 2... Detection line group 3... Coordinate reading unit 4... Coordinate indicator 5... Excitation circuit 6... First selection circuit 7...Second selection circuit 8...Amplitude detection circuit 9...Phase detection circuit 10...Amplitude storage means 11...Phase storage Means 12...Control circuit 40...Coil 41...First capacitor 42...Switch 43...Second capacitor and above Applicant Seiko Electronics Co., Ltd. Company representative Patent attorney Takayuki Hayashi Configuration of the auxiliary coordinate reading device vLt@s Figure 1 Cross-sectional view of the coordinate reading unit Figure 2 Circuit diagram of the coordinate indicator of the first embodiment Figure 3 The circuit diagram of the coordinate indicator of the second embodiment Circuit diagram of coordinate indicator Figure 4 Circuit diagram of coordinate indicator of third embodiment 501FIVFt50f8 51 Amplification 0ffl
Figure 6 shows the structure of the excitation circuit! m lb
Figure 7: Explanation of the configuration of the amplitude detection circuit Figure 8: Configuration of the phase detection circuit Explanation of the amplitude and phase of the guidance signal when the prisoner switch is turned on Whistle 111FW Guidance for the distance of the coordinate indicator Explanatory diagram of signal amplitude and phase Figure 11 Procedural amendment 1 issue) January 21, 1991 1, Display of the incident 1990 Patent application No. 313394 2, Title of the invention Wireless coordinate reading device 3, Amendment Patent applicant (232) Representative director of Seiko Electronic Industries Co., Ltd. KMnosuke 4, Agent 5, Specification to be amended (detailed description of the invention) 6. Contents of amendment (11th specification No. 1) In the first line of page 9, change “Show the configuration diagram.” to “
A configuration explanatory diagram is shown. ” I changed my words. (2) Lines 19 and 20 of page 16 of the specification are revised as follows. When the coordinate indicator 4 moves in the direction away from the coordinate reading unit 3 and the distance between the coil 40 in the coordinate indicator 4 and the electromagnetic shielding member 33 increases,

Claims (1)

[Scope of Claims] A. A coordinate reading section in which a plurality of excitation line groups and a plurality of detection line groups are laid one on top of the other, and b. A resonant circuit constituted by a coil and a first capacitor, and at least a switch. and a coordinate indicator formed by connecting one or more circuits in parallel to the resonant circuit with a series circuit consisting of a second capacitor, c, a first selection circuit that sequentially selects the excitation line group, and d, the detection line. a second selection circuit (e) for sequentially selecting the groups; an excitation circuit (f) connected to the first selection circuit and applying an excitation signal having a frequency near the resonant frequency of the resonant circuit of the coordinate indicator to the excitation line group; an amplitude detection circuit connected to the second selection circuit and detecting the amplitude of the induction signal guided to the detection line group; a phase detection circuit h detecting the phase of the induction signal with respect to the excitation signal; and h, the amplitude detection circuit. an amplitude storage means i for storing an output of the circuit; a phase storage means j for storing the output of the phase detection circuit; and a difference between the output of the amplitude detection circuit and the information stored in the amplitude storage means and the phase detection. A wireless coordinate reading device comprising a control circuit that determines the state of a switch in the coordinate indicator based on the difference between the output of the circuit and the information stored in the phase storage means.