JPH047721A - Coordinate input device - Google Patents

Abstract

PURPOSE:To omit a cable securing connection between a tablet and a coordinate pointing device and to improve the operability of a coordinate input device by making use of the coordinate pointing device containing a resonance circuit and an electromagnetic induction phenomenon occurring between two sense line groups. CONSTITUTION:A coordinate pointing device 10 is provided with a resonance circuit consisting of a coil 80 and capacitors 81 and 82 and a pressure-sensitive resistance element 83 which is connected in parallel to the resonance circuit as a switch element. Then the resonance circuit of the device 10 resonates by an alternating field generated from a 1st sense line group S1. Meanwhile an induction signal is produced at a 2nd sense line group S2 by the alternating field generated from the device 10. The coordinates and the state of a switch 84 of the device 10 are known with use of the induction signal. As a result, a cable securing the connection between a tablet and the device 10 can be omitted and the operability of a coordinate input device is improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a coordinate input device for inputting coordinates to an information processing device such as a computer, and particularly! This invention relates to a coordinate input device that applies magnetic induction phenomena.

[Summary of the invention]

The present invention provides a coordinate system having a resonant circuit that sequentially excites one sense line group out of two sense line groups laid along each axis of the XY orthogonal coordinate axes using an excitation circuit and resonates with the excitation signal. When the device is brought close to a sense line, the amplitude and phase of the induced signal induced in the other sense line group are sequentially processed by an amplitude signal detection circuit and a phase signal detection circuit, and these processed induced signals are stored in an amplitude signal storage circuit. and stored in the phase signal storage circuit, and calculate the position of the coordinate indicator from this guidance signal! In other words, it is a coordinate input device designed to obtain coordinates and the state of a switch of a coordinate indicator.

[Conventional technology]

Conventional coordinate input devices include Japanese Patent Laid-Open No. 52-96825 and Japanese Patent Laid-open No. 55-964, both of which were previously filed by the applicant.
There is No. 11.

These coordinate reading devices sequentially detect guidance signals that guide two sense line groups laid along the XY orthogonal coordinate axes using an alternating magnetic field generated by a coordinate indicator, and determine the thickness of the guidance signal of each sense line. The coordinates were determined by comparing the .

[Problems to be Solved by the Invention] However, with this conventional coordinate input device, it is necessary to apply an excitation signal from the tablet to the coordinate indicator in order to generate an alternating magnetic field from the coordinate indicator, and it is necessary to control the state of the switch of the coordinate indicator. In order to detect it, it was necessary to give a switch detection signal from the coordinate indicator to the tablet. Therefore, I had to connect the tablet and the coordinate indicator with a cable.

Therefore, when an operator inputs characters or figures on the coordinate input device, this cable restricts the free movement of the coordinate indicator, making the coordinate input device difficult to operate.

An object of the present invention is to improve upon such conventional drawbacks, and to provide a coordinate input device with good operability by eliminating the cable connecting the tablet and the coordinate indicator.

[Means to solve the problem]

It is composed of a tablet and a coordinate indicator, and the coordinate indicator is provided with a resonant circuit composed of a coil and a capacitor, and a pressure-sensitive resistance element connected in parallel to this resonant circuit as a switch element. A first sense line group having a plurality of sense lines laid parallel to one axis of the orthogonal coordinate axes and spaced apart from each other; and a plurality of sense lines parallel to the other axis and spaced apart from each other. a first scanning circuit that sequentially selects the first sense line group; an excitation circuit that is connected to the first scanning circuit and excites the first sense line group; a second scanning circuit that sequentially selects the second sense line group; an amplitude signal detection circuit that is connected to the second scanning circuit and detects the amplitude of the induced signal guided to the second sense line group; A phase signal detection circuit that detects the phase, an amplitude signal storage circuit that stores the amplitude of the induced signal detected by the amplitude signal detection circuit, and a phase signal storage circuit that stores the phase of the induced signal detected by the phase signal detection circuit. and a control circuit that determines the coordinates and the state of the switch of the coordinate indicator from the information stored in the amplitude signal storage circuit and the phase signal storage circuit.

[Effect]

In the coordinate input device according to the present invention, the resonant circuit of the coordinate indicator resonates due to the alternating magnetic field generated from the first sense line group, and the alternating magnetic field generated from the resonant coordinate ↑ indicator is applied to the second sense line group. It takes advantage of the fact that an inductive signal is induced by a magnetic field.

When the first sense line, which is sequentially excited by the first scanning circuit, is close to the coordinate indicator, a larger current flows through the resonant circuit of the coordinate indicator. At this time, the second
If the distance between the second sense line sequentially selected by the scanning circuit and the coordinate indicator is short, a larger induced current (induced signal) is generated in the second sense line.

For example, the largest induced signal is generated when the first sense line that is excited is selected directly below the coordinate indicator and the second sense line is selected directly below the coordinate indicator. Therefore, by storing the amplitude of the guidance signal detected at that time in accordance with the positions of the selected first and second sense lines in the guidance signal storage circuit, and comparing the stored amplitudes by the control circuit, the coordinate indicator The position or coordinates of can be found.

Furthermore, the phase of the induced signal generated on the second sense line is determined by the constants of each circuit element of the coordinate indicator. That is, by applying pressure to the pressure-sensitive resistance element used as a switch element of the coordinate indicator, the resistance value can be changed and the phase of the induced signal can be changed. Therefore, the state of the switch of the coordinate indicator can be determined by detecting the phase of the guidance signal, storing it in the phase signal storage circuit, and detecting a change in the stored phase by the control circuit.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 12. FIG. 1 shows a configuration diagram of a coordinate input device according to the present invention, in which 1 indicates a sense line group and Sl
is a first sense line group having sense lines y1 to yn, S2 is a second sense line group having sense lines x1 to X-, and 2 is a first scanning circuit that sequentially selects the first sense line group S1. , 3 is a second scanning circuit that sequentially selects the second sense line group S2, 4 is an excitation circuit that excites the first sense line group S1, and 5 is an inductive signal generating circuit for the second sense line group S2. An amplitude signal detection circuit that detects the amplitude; 6 a phase signal detection circuit that detects the phase of the induced signal; 7 a control circuit composed of a general CPU circuit; and 8 an amplitude signal storage circuit that stores the amplitude of the induced signal. , 9 is a phase signal storage circuit for storing the phase of the guidance signal, and 10 is a coordinate indicator having a resonance circuit (not shown).

FIG. 2 shows a configuration diagram of the excitation circuit 4. 40 is a low-pass filter, 41 is an amplification section, and 42 is a resistance element.

FIG. 3 shows a configuration diagram of the first scanning circuit 2. As shown in FIG.

Note that the same symbols as in FIG. 1 indicate the same ones as in FIG. 1, 20 is a decoder, 21 is a switch element 211 to 21
101 is an excitation signal output from the excitation circuit 4, and 102 is a selection signal output from the control circuit 7.

Further, although the details of the second scanning circuit 3 are not shown, it has the same configuration as the first scanning circuit 2, and the difference is that the excitation signal 101 is input to the first scanning circuit 2. ,
The point is that the second scanning circuit 3 outputs the guidance signal 104.

FIG. 4 shows a configuration diagram of the amplitude signal detection circuit 5.

50 is an amplification section, 51 is a detection section, 52 is a smoothing section, 53 is A
This is a D conversion section.

A configuration diagram of the phase signal detection circuit 6 is shown in the fifth panel.

60 is an amplifier section, 61 is a comparator, 62 is 1JHtt
l logical OR element, 63 is a resistance element, 64 is a capacitor,
65 is an AD conversion section.

FIGS. 6 and 7 show a waveform diagram of a guiding signal and an explanatory diagram for calculating coordinates.

FIG. 8 shows a timing diagram of the phase signal detection circuit.

FIG. 9 shows a circuit included in the coordinate indicator 10. 80
81 is a coil, 81 is a capacitor, and 82 is a variable capacitor, which constitute an LC resonance circuit. 83 is a pressure sensitive resistance element, which is connected in parallel to the LC resonant circuit.

FIGS. 10 and 11 show simple structural diagrams of a stylus pen and a cursor, particularly the switch portion, as typical coordinate indicating devices. In both figures, the same symbols as in FIG. 9 indicate the same things. In Figure 10, 90
is the case, 91 is the capacitor 81 and variable capacitor 82
It is a circuit board having a coil 80 and a pressure sensitive resistance element 83.
are connected (wiring not shown). A stylus core 92 is attached to a chuck 93, and the stylus core 92 and chuck 93 are free with respect to the case 90. In FIG. 11, 95 is a case to which the coil 80 is attached, 96 is a case, and 97 is a circuit board having a capacitor 8I, a variable capacitor 82, and a pressure-sensitive resistance element 83, to which the coil 80 is connected (wiring is not shown). 98 is the cursor button and the board bar 29
9 is attached to the case 96 and can be moved up and down.

FIG. 12 shows an explanatory diagram of the amplitude signal storage circuit 8.

The operation of this embodiment will be explained below. In FIG. 1, the coordinate indicator 10 is a sense line x4 and a sense line y.
4 (section A in FIG. 1) will be explained.

The excitation circuit 4 converts the excitation clock 100 (614.4 KHz square wave) outputted from the control circuit 7 into a sine wave by removing harmonics with a low-pass filter 40, and sets it to a predetermined voltage in an amplification section 41. , the excitation signal 10 becomes a sine wave of 614.4KH2 through the resistance element 42 for current control.
1 to the first scanning circuit 2.

The first scanning circuit 2 first selects the sense line y1 of the first sense line group S1 based on the selection signal 102 output from the control circuit 7. That is, in FIG. 3, the decoder 20 selects the analog switch 21 according to the selection signal 102.
1 and sends the excitation signal 101 to the first sense line y1.
A magnetic field of 614.4 KHz is generated from the sense line y1. Meanwhile, the second scanning circuit 3 sequentially selects the second sense line group S2 as xi, x2, . . . xm using the selection signal 103 output from the control circuit 7 during this time. Then, the scanning of the second sense line group is -
If the first scanning circuit 2 is successfully completed, the first scanning circuit 2 selects the sense line y2 of the first sense line group S1 by the selection signal 102 output from the control circuit 7, and the second scanning circuit 3 selects the sense line y2 of the first sense line group S1 during this time. Selection signal 10 output from control circuit 7
3, the second sense line group S2 is xl, x2 ・
...X- and so on. This scanning is repeated in the same manner, and finally the first scanning circuit 2 selects the sense line group opening of the first sense line group S1, and the second scanning circuit 3 selects the sense line group opening of the first sense line group S1.
During this period, the second sense line group S2 is
...xm are selected in sequence.

The series of selection operations up to this point, that is, the sense line y1
The scanning from the selection of the sense line x1 to the selection of the sense line yn and the sense line X- is called full-surface scanning.

The amplitude signal detection circuit 5 and the phase signal detection circuit 6 shape the waveform of the induced signal 104 generated in the second sense line group S2 that is sequentially selected during full-surface scanning, and determine its magnitude (amplitude).
and the phase are sequentially digitized to produce an amplitude signal 105 and a phase signal 106.

Further, the digitized amplitude signal 105 and phase signal 105 are sequentially stored in the amplitude signal storage circuit 8 and the phase signal storage circuit 9 by the control circuit 7. Details of the storage method in the amplitude signal storage circuit 8 and the phase signal storage circuit 9 will be described later.

Here, details regarding the magnitude of the guidance signal 104 will be explained based on FIG. 6. FIG. 6 is a waveform diagram when the coordinate indicator is located at part A in FIG.
．． 103 and the induced signal (signal 110 in FIG. 4) before being AD converted in the amplitude signal detection circuit 5, a is A.
This is the guiding signal when the first sense line y4 and the second sense line x4 are selected, and is the largest signal among the signals detected during the entire surface scan. The reason is that the coordinate indicator IO of the first sense line group
When selecting the sense line y4 that is closest to the coordinate indicator 10, a large current is generated in the resonant circuit of the coordinate indicator, and the sense line x4 that is the closest to the coordinate indicator 10 of the second sense line group is selected. This is because when selected, the largest induced current (induced signal) is generated by the magnetic field generated from the coordinate indicator.

b and C are the inductions when the left and right sides of part A, that is, the first sense line y4 and the second sense line x3, are selected, and when the first sense line y4 and the second sense line x5 are selected. It's a signal. The magnitude of the induced signal S and the induced signal C is such that the induced current flowing through the resonant circuit of the coordinate indicator 10 is the same, but the magnitude of the induced signal S and the induced signal C is determined by the distance between the coordinate indicator 10 and the selected second sense line. , becomes smaller than the induced signal a. Furthermore, d and e are the upper and lower portions of part A, that is, the first sense line y3 and the second sense line x.
4 is selected, and when the first sense line y5 and the second sense line x4 are selected. The magnitude of the guidance signal d and the guidance signal e is such that, although the second sense line for detecting the guidance signal is common, the coordinate indicator 1° and the selected first sense line are separated by a distance. The induced current flowing through the resonant circuit of the coordinate indicator 10 becomes smaller and becomes smaller than the induced signal a.

Although the guidance signals a to e have been explained above, the relationship between the position of the sense line selected from the first sense line group S1 and the second sense line group S2 and the coordinate indicator 10 also applies to other signals. Its size is determined by Note that since the first sense line group S1 and the second sense line group S2 are orthogonal to each other, basically, the second sense line group 2 is directly connected to the signal generated from the first sense line group 1. Therefore, as explained above, guidance is performed based on the positional relationship between the position of the sense line selected from the first sense line group S1 and the second sense line group S2 and the coordinate indicator 10. You can consider the size of the signal.

Now, focusing on the above five guidance signals a''-e, a method of calculating coordinates will be explained.

First, a method for calculating the X coordinate will be explained based on FIG. 7, focusing on the guidance signals a, b, and c. Figure 7 (1) shows the first
This is an enlarged view of the area around part A shown in the figure, and the coordinate indicator l
O is on the center of sense line y4 from the center LO of sense line x4 to L between sense line x4 and sense line x5
Consider the case of moving to l. 7th [111il (2)
and (3) show the guidance signals a, b, and c when the coordinate indicator 10 is located at LO and Ll. First, the coordinate indicator 10 shown in FIG. 7(2)
The case where is located at LO will be explained. As described above, the guide signal a is a signal when the sense line x4 is selected while the sense line y4 is selected, the guide signal C is a signal when the sense line x3 is selected, and the guide signal C is a signal when the sense line x5 is selected. At this time, the induced signal a becomes the largest value,
Guidance signal C includes coordinate indicator 10 and sense line x3
The case where the coordinate indicator 10 shown in FIG. 7(3) is located at Ll in the 0th order in which the distance between the coordinate indicator 10 and the sense line x5 are the same and the distance between the coordinate indicator 10 and the sense line x5 will be explained.

At this time, the guidance signals a and C are the distance between the coordinate indicator 10 and the sense line x4 and the distance between the coordinate indicator 10 and the sense line x4.
Since the distances of 5 are the same, they are equal. Here, the coordinates can be calculated by applying the method proposed by the present applicant (Japanese Patent Laid-Open No. 55-96411). That is, the calculation defined by the following equation is performed based on the above-mentioned guidance signal.

Formula -I Q= (Vp -Vp+1) / (Vp
-Vp4) However, Vp+1 > Vp-1 In the above equation, the guidance signal a is set to Vp, and the guidance signal S is set to Vp.
−1, the guidance signal C is assigned to Vp+1, and the coordinate indicator 1 is
FIG. 7 (4) shows the change in Q shown in 6-1 when 0 is moved from LO to Ll. It is clear from the above explanation that when the coordinate indicator 10 is at the LO position, Q-1, and when the coordinate indicator 10 is at the Ll position, Q=0. Furthermore, when the coordinate indicator 10 is located between LO and Ll, Q corresponds one-to-one with this position, Q<Q<1
Takes values in the range of . Therefore, by determining the characteristics of this Q experimentally in advance, the induced signals a, b,
Calculate Q from c, and from this Q, LO- on the sense line
The exact position of the coordinate indicator between Ll can be determined. Furthermore, the value of this Q and the sense line where the induced signal a was detected! The X coordinate can be found by For details of this coordinate calculation method, please refer to Japanese Unexamined Patent Publication No. 55-9
6411, so it will be omitted here.

Next, a method for calculating the X coordinate will be explained based on FIG. 7, focusing on the guidance signals a, d, and e. The X coordinate can also be considered in the same way as the X coordinate described above. Figure 7 (1)
Now, consider a case where the coordinate indicator 10 moves on the center of the sense line x4 from the center LO of the sense line y4 to L2 between the sense line y4 and the sense line y5. FIGS. 7(5) and (6) show the guidance signals a, d, and e when the coordinate indicator 10 is located at LO and L2. First, the case where the coordinate indicator 10 shown in FIG. 7(5) is located at LO will be described. As mentioned above, the guide signal a selects the sense line x4 while selecting the sense line y4, the guide signal d selects the sense line x4 while selecting the sense line y3, and the guide signal e selects the sense line y5. This is the signal when sense line x4 is selected while . At this time, the guidance signal a becomes the largest value, and the guidance signals d and e become equal because the distance between the coordinate indicator 10 and the sense line y3 and the distance between the coordinate indicator 10 and the sense line y5 are the same.

Next, the case where the coordinate indicator 10 shown in FIG. 7(6) is located at L2 will be described. At this time, the guiding signals a and e
are equal because the distance between the coordinate indicator 10 and the sense line y4 and the distance between the coordinate indicator 10 and the sense line y5 are the same. Therefore, as in the case of the X coordinate described above, the characteristics of Q when the coordinate indicator 10 is moved from LO to L2 are determined based on formula-1, with the guidance signal a being Vp and the guidance signal d being
By substituting Vp-1 for Vp-1 and substituting the induced signal e for ■ρ+1, the result is as shown in FIG. 7 (7). This is shown in Figure 7 (4
), almost the same characteristics as in the case of the X coordinate of
As in the case of coordinates, the Y coordinate can be determined using this characteristic of Q.

The above processing is performed by reading the amplitude signal 05 stored in the amplitude signal storage circuit 8 in the control circuit 7 which is constituted by a general CPU circuit.

Next, details regarding the phase of the guiding signal 104 will be explained based on FIG. 8. The coordinate indicator 10 has a circuit configuration shown in FIG. 9, and the resonant frequency of the LC resonant circuit is adjusted to be slightly shifted from the frequency of the alternating magnetic field generated from the first sense line group S1. Therefore, the phase of the induced current induced in the LC resonant circuit changes depending on the change in the resistance value of the pressure sensitive resistance element 83. Figures 10 and 11 show structural diagrams of the stylus pen and cursor. In the case of a stylus pen, when the operator instructs something (switches on) with the stylus pen, that is, when the stylus tip 92 touches the reading surface, pressure is applied to the pressure-sensitive resistor through the stylus tip 92 and the chuck 93. It is transmitted to element 83 and its resistance value decreases. In the case of a cursor, when the operator presses the cursor button 98 (switch on), the pressure is applied to the pressure sensitive resistive element 83 and its resistance value decreases. Therefore, the phase of the induced current generated in the resonant circuit of the coordinate indicator 10 by the magnetic field generated from the first sense line group S1 changes due to the decrease in the resistance value of the pressure sensitive resistance element 83, and The phase of the induction signal 104 generated at S2 also changes accordingly. For example, if the resonant frequency of the LC resonant circuit of the coordinate indicator is
If the frequency is adjusted higher than the frequency of the alternating magnetic field generated from the sense line group S1 of There is a delay because the resistance value of element 83 becomes low.

The phase signal detection circuit 6 detects the induction signal 104 which is a minute signal.
is amplified by the amplifying section 60, converted into a rectangular wave induced signal 120 by the comparator 61, and inputted to the exclusive OR element 62. The exclusive OR element 62 performs an exclusive OR of the induced signal 120 converted into a rectangular wave and the excitation clock 100 to generate a phase signal 121. Guidance signal 10 in Figure 8
4 and the induction signal 120, the waveform shown by a solid line is when the switch is off, and the waveform shown by a broken line is when the switch is on. As shown in the figure, the pulse width of the phase signal 121 changes as the phase of the induction signal 104 changes due to on/off of the switch. The phase signal], 21 is integrated by a resistive element 63 and a capacitor 64 to convert the pulse width into a voltage, and is further digitized by an AD converter 65 to become a phase signal 106 and output to the control circuit 7. Therefore, in the control circuit 7, the on/off state of the coordinate indicator 100 can be determined based on whether the phase signal 106 is larger or smaller than a predetermined darkness value. Note that the pressure sensitive resistance element 8
Since 3 is an element whose resistance value changes in an analog manner depending on the strength of the applied pressure, the sensitivity of the switch can be changed by changing the set value of the dark value of the on/off judgment mentioned above. It goes without saying that the pressure applied to the switch (stylus lead 92 in the case of a stylus pen, cursor button 98 in the case of a cursor) can be detected not only by the /off judgment but also by detecting the amount (voltage) exceeding a predetermined darkness value. stomach.

Here, a method of storing the amplitude signal 105 in the amplitude signal storage circuit 8 and a method of reading it from the amplitude signal storage circuit 8 will be explained based on FIG.

The amplitude signal storage circuit 8 is a random access memory (R
AM), and its reading and writing are controlled by a control circuit 7. FIG. 12 shows memory muffing in which the amplitude signal 105 is stored in a random access memory, and the address is assigned starting from address 1001 (in decimal representation). In the case of the embodiment shown in FIG. 1, there are m x n combinations of selections of the first sense line group S1 having n sense lines and the second sense line group S2 having n sense lines. becomes. Therefore, the address space of the amplitude signal storage circuit 8 required to store all the amplitude signals 105 obtained when full-surface scanning is performed once is mxn bytes (assuming the AD-converted amplitude signal 105 is 8-bit data). , the addresses range from address 1001 to address 1000+(mxn). Then, the amplitude signal 105 is sequentially stored (written) in the amplitude signal storage circuit 8 from address 1001 in the order in which the control circuit 7 scans the entire surface, that is, the y-th (1≦y ≦n), the amplitude signal 105 when the second scanning circuit 3 selects the Xth (l≦x5m) sense line is 100(1(y-1) According to this method, the guiding signals a-e shown in FIG. 7 of the above embodiment are stored at the address shown in FIG. 12.

Next, a method of reading out the induced signals a-e from the amplitude signal storage circuit 8 will be explained. First, the amplitude signal storage circuit 8
By detecting the maximum value among them, the induced signal a can be determined, and from the address (100013 m + 4), the positions of the first and second sense lines where the induced signal a has been detected can be determined. Further, since the amplitude signal 105 is sequentially stored in the amplitude signal storage circuit 8 according to the above method, the left and right guidance signals of the guidance signal a are stored at the +1 address of the address where the guidance signal a is stored, that is, 1000+3 m
A guidance signal is stored at address +3, but guidance signal C is stored at address 1000+3m+5. Further, the guidance signals above and below the guidance signal a are stored at addresses ±m of the address where the guidance signal a is stored, that is, the guidance signal d is stored at address 1000+2m+4, and the guidance signal e is stored at address 100Q+4m+4. ing.

Therefore, by detecting the maximum value in the amplitude signal storage circuit 8, information necessary for coordinate calculation, that is, in the case of the above embodiment, the first and second senses that have detected the guiding signal a-e and the guiding signal a. You can know the position of the line.

On the other hand, the phase signal storage circuit 9 has the same configuration as the amplitude signal storage circuit 8, and addresses are assigned starting from address 1001+(mxn), and the phase signals 106 are written to the phase signal storage circuit 9 in the order in which the entire surface is scanned. By setting the phase signal 10 when a certain sense line is selected,
6, the amplitude signal 105 at that time is always stored at an address obtained by adding (mXn) to the address stored in the amplitude signal storage circuit 8. Therefore, the control circuit 7 reads from the phase signal storage circuit 9 the phase signal 106 of the address obtained by adding (m The states of ten switches can be detected.

Furthermore, the phase signal 106 used for threshold determination is the amplitude signal 10
5 is not the maximum value, but if the induced signal 104 does not have a certain amplitude, the induced signal 120 output from the comparator 61 of the phase signal detection circuit 6 will become unstable. This is preferable.

In this way, the maximum value of the induced signal from the amplitude signal storage circuit 8 by the control circuit 7, the positions of the first and second sense lines where the maximum value was detected, and the upper, lower, left, and right directions of the induced signal where the maximum value was detected. By detecting the signal and further detecting the phase signal when the amplitude signal 105 is at its maximum value from the phase signal storage circuit 9, the coordinates of the coordinate indicator and the state of its switch can be determined as described above.

Note that various methods can be considered for the processing in the control circuit 7. For example, in terms of scanning, if the maximum value of the guidance signal necessary for coordinate calculation is detected in the entire surface scan, the next time, the entire surface scan will not be performed, and only the vicinity of the maximum value of the detected guidance signal will be scanned (this scan will be performed). A case will be described with reference to FIG. 1, in which two regions are set on the top, bottom, left and right of the sense line where the maximum value of the induced signal is detected as the regions of 0 partial scanning, which is a method of calculating coordinates (referred to as partial scanning). A in Figure 1
When the coordinate indicator 10 is located in the area, the partial scanning area includes sense lines y2 to y6 of the first sense line group S1 and sense line x of the second sense line group S2.
The range is from 2 to x6. That is, sense line y2
scanning is performed from selection of sense line x2 to selection of sense line y6 and sense line x6, and the amplitude signal 105 and phase signal 106 for 25 types of induced signals are sequentially sent to the amplitude signal storage circuit 8 and the phase signal storage circuit 9. Make me remember. Then, the coordinate calculation process shown in the above embodiment is performed. In this embodiment, compared to the previous embodiment, the address space of the amplitude signal storage circuit 8 and the phase signal storage circuit 9 only needs 25 bytes each, and the time required for - times of scanning is shortened. This has the advantage of improving the ability to detect coordinates.

Further, as another example of the processing of the control circuit 7, there is a method of performing dark value determination without detecting the maximum value in the entire surface scan.

That is, if a guidance signal larger than the darkness value is detected in the full-scale scan, the process moves to the partial scan. According to this method, it is possible to shift to partial scanning during full-scale scanning, reducing the time until the first coordinate calculation,
This has the advantage of improving the responsiveness of the coordinate input device.

Furthermore, regarding the processing of coordinate calculation, the method is not limited to the method of calculating coordinates using the maximum value of the guidance signal and the three types of signals on both sides thereof, as shown in the above embodiment, but also the method of calculating the coordinates using the maximum value or the guidance signals around the maximum value. Various currently invented methods for calculating coordinates can be applied.

〔Effect of the invention〕

As explained above, according to the present invention, two sense line groups are laid along each axis of the XY orthogonal coordinate axes, one sense line group is sequentially excited by an excitation circuit, and resonates with this excitation signal. When a coordinate indicator having a resonant circuit is brought close to a sense line, the amplitude and phase of the induced signal induced in the other sense line group are sequentially processed by an amplitude signal detection circuit and a phase signal detection circuit, and the processed induction By storing the signal in the amplitude signal storage circuit and the phase signal storage circuit, and determining the position of the coordinate indicator, that is, the coordinates and the state of the switch of the coordinate indicator, from this guidance signal, it is possible to easily connect the cable from the tablet to the coordinate indicator. Since it is no longer necessary to provide a signal via the tablet, the cable between the tablet and the coordinate indicator, which is present in conventional coordinate input devices, can be eliminated.

For this reason, the coordinate indicator that an operator uses when inputting characters or figures on a coordinate input device can be used with the same feeling as an everyday writing instrument, and the movement of the coordinate indicator A coordinate input device with good operability without any restrictions can be provided. Further, there is no failure due to disconnection of the cable between the tablet and the coordinate indicator, which was one of the drawbacks of conventional coordinate input devices, and the reliability of the coordinate input device can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram of an excitation circuit, FIG. 3 is a block diagram of a scanning circuit, FIG. 4 is a block diagram of an amplitude signal detection circuit, and FIG. is a configuration diagram of the phase signal detection circuit, FIG. 6 is a waveform diagram of the guiding signal, FIG. 7 is an explanatory diagram for calculating coordinates, FIG. 8 is a timing diagram of the phase signal detection circuit, and FIG. 9 is a coordinate indicator. Figure 10 is the structure diagram of the stylus pen, Figure 11 is the structure diagram of the cursor, and Figure 1 is the structure diagram of the stylus pen.
FIG. 2 is an explanatory diagram of the induction signal storage circuit. 1... Sense line group 2.3... Scanning circuit 4... Excitation circuit 5... Amplitude signal detection circuit 6... Phase signal detection circuit 7...・ Control circuit Amplitude signal storage circuit Phase signal storage circuit Coordinate indicator or higher

Claims (1)

[Claims] Consisting of a tablet and a coordinate indicator, the coordinate indicator has a resonant circuit composed of a coil and a capacitor, and is connected in parallel to the resonant circuit as a switch element of the coordinate indicator. The tablet has a first sense line group having a plurality of sense lines parallel to one axis of the XY orthogonal coordinate axes and equally spaced from each other; a second sense line group having a plurality of sense lines laid in parallel and at regular intervals; a first scanning circuit that sequentially selects the first sense line group; an excitation circuit which is connected and excites the first sense line group; a second scanning circuit which sequentially selects the second sense line group; and a second scanning circuit which is connected to the second scanning circuit and which excites the first sense line group. an amplitude signal detection circuit that detects the amplitude of a guidance signal induced by the guidance signal; a phase signal detection circuit that detects the phase of the guidance signal; and an amplitude signal that stores the amplitude of the guidance signal detected by the amplitude signal detection circuit. a storage circuit, a phase signal storage circuit that stores the phase of the guidance signal detected by the phase signal detection circuit, and coordinates and the coordinate indicator from the information stored in the amplitude signal storage circuit and the phase signal storage circuit. and a control circuit for determining the state of the switch.