JPH06124162A - Digitizer - Google Patents

Abstract

PURPOSE:To easily detect operation information even when a switch is operated in any timing by comparing the sum of induced voltage measured last time and this time on a prescribed condition, and executing the detection processing of a switch operation based on the compared result. CONSTITUTION:When a switch SW1 of a position instructor 2 is operated, capacitors C0 and C1 are connected in parallel, and a tuning circuit is formed of the capacitors C0 and C1, and a coil L. Therefore, at the time of detecting the operation information of the switch SW1, a processing circuit 17 supplies the driving currents of the same frequency as the tuning frequency of the tuning circuit formed of the capacitor C0 and the coil L to a driving coil group 11 so that the maximum induced voltage from a sense coil 14 side can be obtained. When any switch is operated, the frequency of the driving currents is not matched with the tuning frequency, and the detected voltage value is decreased, even when the position instructor 2 is not moved. Therefore, the operation of the switch can be detected by detecting the decrease of the voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digitizer for detecting the position and switch information of a position pointing device mounted on a tablet.

[0002]

2. Description of the Related Art This type of digitizer comprises a tablet and a position indicator. The tablet includes a drive coil group including a plurality of parallel loop coils, a sense coil group including a plurality of loop coils orthogonal to the drive coil group and parallel to each other, and a processing circuit.

Here, when detecting the position of the position indicator, the processing circuit first sequentially selects the drive coil group to supply the drive current. Then, a magnetic field is generated from the energized drive coil, and if the position indicator is mounted on this drive coil at this time, a current is induced in the ring-shaped coil of the position indicator by the generated magnetic field. A magnetic field is generated from the position indicator by inducing a current in the coil of the position indicator, and the generated magnetic field induces a voltage in the sense coil orthogonal to the drive coil. The processing circuit detects this induced voltage by sequentially selecting the sense coil group,
The position of the position indicator is detected from the selected address given to the drive coil group, the selected address of the sense coil group, and the value of the induced voltage. In addition, when detecting the operation information of the switch provided in the position indicator, a drive current having a frequency different from the frequency of the drive current is sequentially supplied to the drive coil group. As a result, an induced voltage tuned to the frequency of the tuning circuit composed of the coil and the capacitor of the position indicator based on the switch operation is generated in the sense coil group, and the switch operation information of the position indicator is detected.

FIG. 6 is a flow chart showing the operation of the above digitizer. The operation of this digitizer is divided into three operations including a position determination step of the position indicator, a switch state detection step of the position indicator and a data output step. be able to. That is, as the position determining step, first, step 60
Then, determine the operation selection for position detection of the position indicator,
If it is determined that this is the stage for detecting the rough position of the position indicator, a full search for detecting the entire area on the tablet is performed in step 61, and as a result, the area (area) in which the position indicator is present is roughly recognized. Yes, step 6
If it is determined to be "Y" in 2, the process moves to the precision position determination process of step 65 in order to specify the exact position of the position indicator.

If it is determined in step 60 that the detecting operation of the position indicator is in the step of detecting the quasi-coarse position, a near search is performed in step 63 to detect the vicinity area where the position indicator is located, and in step 64. After determining the area recognition, the process proceeds to the precision position determination process of step 65.
Further, when it is determined in step 60 that the detecting operation of the position indicator is in the step of detecting the fine position, the process immediately proceeds to the fine position determining process of step 65.

In the precision position determination process of step 65, the precision position of the position indicator is detected. When the coordinate position of the position indicator is calculated and the "coordinate recognition" of step 66 becomes "Y" in the above process. After the "coordinate detection" in step 67, the output coordinate value is set in the buffer or the like in step 68. As a result of the detection operation, the area in which the position indicator is located cannot be specified, and when “Area recognition” in steps 62 and 64 is determined to be “N”, and the coordinates cannot be calculated in the precise position determination processing, the step is not performed. When the “coordinate recognition” of 66 is “N”, the output coordinate value is not set. The above is the processing in the position determination step of determining the position of the position indicator.

Next, as the process of the switch state identification stage, the processes shown in steps 69 to 71 are performed. That is,
In step 69, it is determined whether it is the switch identification timing. This switch identification is performed, for example, at a timing of every 50 ms, and when the switch identification timing comes, a switch identification operation is performed in step 70 to determine which switch is operated. As a result, the switch information is set in the buffer or the like. Then, as the final stage of data output,
In step 72, the coordinate value and the switch information set in the buffer or the like are output to the host device.

[0008]

The conventional digitizer which performs such a detecting operation discriminates whether or not the switch provided on the position indicator is operated at every predetermined time. Therefore, during this switch discriminating timing. There was a problem that it could not be detected when the switch was operated. Therefore, an object of the present invention is to make it possible to detect a switch at any timing when it is operated.

[0009]

In order to solve such a problem, the present invention provides a tablet with a drive coil group and a sense coil group, and comprises a coil, a plurality of switches and a capacitor, and a plurality of different tuning frequencies. Equipped with a plurality of tuning circuits having a, the drive coil group to sequentially select the drive frequency corresponding to the plurality of different tuning frequencies, and apply a current of this drive frequency,
When detecting the position of the position indicator on the tablet and the switch operation information from the level of the induced voltage generated in the sense coil group, the position on the tablet based on the arrangement position of each loop coil forming the drive coil group and the sense coil group is detected. Comparing the area into a plurality of areas, and comparing the sum of the induced voltage measured last time and the sum of the induced voltage measured this time in the vicinity of the area where the position indicator is located under a predetermined condition. The means for shifting to the detection processing of the switch operation information according to the comparison result of the comparison means, and the driving frequency of the current to be passed through the driving coil group at the time of shifting to the detection processing are set to the high frequency side of a plurality of different tuning frequencies or low. The means for selecting sequentially from the frequency side and the level of the induced voltage for each selected drive frequency are detected, and the voltage level of the frequency is the previous voltage level. Ri that is provided with a means for identifying any one of a plurality of different tuning frequencies by detecting the low.

[0010]

[Operation] In the area near the area where the position indicator is located, the sum of the induced voltage measured last time and the sum of the induced voltage measured this time are compared under a predetermined condition, and the switch operation information is based on the comparison result. Detection processing is executed. As a result, the switch operation information can be detected no matter what timing the switch is operated. In addition, when the process proceeds to the switch operation information detection process, the drive frequency of the current flowing through the drive coil group is selected in order from the higher frequency among a plurality of different tuning frequencies, and the measured induced voltage level is higher than the previous measured level. When it is low, one of the tuning frequencies is specified from the previous voltage level and the switch operation information is detected. As a result, the switch operation information can be efficiently detected.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a digitizer according to the present invention. In the figure, the digitizer comprises a tablet 1 and a position indicator 2. Here, the tablet 1 for detecting the position of the position indicator 2 includes a drive coil group 11 including a plurality of parallel loop coils, and a Y scanner circuit 1 for sequentially selecting the drive coil group 11.
2, a drive circuit 13 for controlling the Y scanner circuit 12 to supply a drive current to the selected drive coil, a sense coil group 14 orthogonal to the drive coil group 11 and arranged in parallel with each other, and a sense coil group 14. Sense coil group 1 for controlling the X scanner circuit 15 and the X scanner circuit 15 for sequentially selecting
It is composed of a sense circuit 16 for detecting the induced voltage of No. 4 and a processing circuit 17. The processing circuit 17 performs a processing calculation of the designated coordinates of the position indicator 2 and transmits the processing result to the higher-level device 18.

Here, when the processing circuit 17 detects the pointing coordinate of the position pointing device 2, first, the processing circuit 17 controls the driving circuit 13 so that Y is detected.
A drive current is sequentially supplied to the drive coil group 11 via the scanner circuit 12. Then, a magnetic field is generated from the energized drive coil, and if the position indicator 2 is placed on this drive coil at this time, the generated magnetic field causes the position indicator 2 to move.
An electric current is induced in the coil. As a result, the position indicator 2
Generates a magnetic field, and the generated magnetic field induces a voltage in the sense coil orthogonal to the drive coil. This induced voltage is transmitted through the X scanner circuit 15 to the sense circuit 1
6 is detected and transmitted to the processing circuit 17. The processing circuit 17 calculates the position of the position indicator 2 from the selected address of the drive coil group 11, the selected address of the sense coil group 14, and the value of the induced voltage, which are given when controlling the drive circuit 13.

FIG. 2 is a circuit diagram of the position indicator 2, which includes a coil L, capacitors C0 to C4, and switches SW1 to S.
It is composed of W4. Here, each switch SW1
When the SW4 is not operated, the position indicator 2 is provided with a tuning circuit having a tuning frequency determined by the capacitances of the capacitor C0 and the coil L. If a current of the same frequency as the tuning frequency of this tuning circuit is applied to the drive coil group 11,
The maximum induction voltage is obtained from the sense coil group 14, and therefore, when the position detection of the position indicator 2 is performed, the processing circuit 17 supplies the drive current having the same frequency as the tuning frequency of the tuning circuit. Feed group 11.

Further, for example, the switch SW of the position indicator 2
When 1 is operated, the contact of the switch SW1 is closed and the capacitors CO and C1 are connected in parallel. And
The capacitors CO and C1 connected in parallel to the position indicator 2
And a tuning circuit having a tuning frequency determined by each capacitance of the coil L is formed. Therefore, when detecting the operation information of the switch SW1, the processing circuit 17 drives the drive current having the same frequency as the tuning frequency of the tuning circuit so that the maximum induced voltage is obtained from the sense coil group 14 side. Supply to the coil group 11. In addition, other switches SW2 to S
The same applies when W4 is operated. In these cases, since tuning circuits having tuning frequencies different from the above frequencies are formed in the position indicator, the tuning frequencies of the tuning circuits are detected when the switch operation information is detected. A drive current having a frequency matching with is supplied to the drive coil group 11. In addition,
Tuning frequency when the switch in the position indicator 2 is not operated is the reference frequency ArufaKH _Z about 500KH _Z, the switches SW1, SW2, SW3, SW4
The tuning frequencies when is operated are βKH _Z and
γKH _Z, δKH _Z, has a εKH _Z, which are set so that α>β>γ>δ> ε sequentially at an interval of about 10～20KH _Z to the alpha.

In this way, the processing circuit 17 detects the position of the position indicator 2 and the switch operation information, and the detection processing is performed by executing software. FIG. 3 shows an induced voltage measurement area in the case of detecting the position information, switch operation information, etc. using software, and this measurement area corresponds to the arrangement area of each loop coil on the tablet. . Here, as shown in FIG. 3 (A), the induced voltage at a certain time measured in each of the regions A to E is e1 ′ to
e5 ′, at this time, the position indicator 2 exists in the area A which is the center of each area, and the drive coil group 11 is supplied with a drive current of αKH _Z for detecting the position of the position indicator 2. It was assumed that In this case, the measured induced voltage of each region at the next time point becomes e1 to e5 as shown in FIG. 3B, and at this time, the driving coil group 11 has the same αK as described above.
Assuming that the drive current of H _Z is given, if the position of the position indicator 2 does not move during this period, the voltage values e1 ′ to e5 ′ of FIG. 3A and the voltage value e1 of FIG. ~ E5 are equal to each other.

However, even if the position indicator 2 does not move, if any of the switches of the position indicator 2 is operated during this time, the frequency of the drive current and the tuning frequency do not match, and as a result, the circuit diagram 3 (B) The voltage values e1 to e5 shown in () decrease. The present invention focuses on the drop in the induced voltage value that occurs when the switch is operated, and determines the voltage drop amount to detect the switch operation information.

Here, when the switch operation information is actually detected, the voltage comparison is not performed only in the area A in which the position indicator 2 exists, but the added value of the voltages in the left and right areas B and C of the area A and the area The added value of the voltages in the upper and lower areas D and E of A is compared with the previous measured value. And equation (1),
When any of the conditions (2) is satisfied, the operation proceeds to the switch operation information detection operation. (E2 ′ + e3 ′) × T ≧ e2 + e3 (1) (e4 ′ + e5 ′) × T ≧ e4 + e5 (2) Here, T is a coefficient, which is usually 0.9 to 0.
Set to 7.

In this way, the operation shifts to the switch information detection operation, but the frequency of the drive current (drive frequency) applied to the drive coil group 11 when the switch information is detected.
Order, so as to provide switching from ArufaKH _Z is a high frequency as the five stages to IpushironKH _Z is a low frequency. This is done for the purpose of shortening the processing time because the processing time for measuring the induced voltage occupies a considerable time in the switch information detection processing.

FIG. 4 is an explanatory diagram showing the operation of detecting the position of the position indicator 2 and the switch operation information.
The drive frequency at which the 1 shows the status of the voltage induced in the sense coil group 14 when given switched in five stages from ArufaKH _Z to εKH _Z. It should be noted that FIG. 7A shows the non-operation state of each switch, and FIG.
(C), (D), (E) are switches SW1,
It shows a state in which SW2, SW3, and SW4 are operated. From this figure, it can be seen that the voltage level decreases at a peak of the tuning frequency and further away from the tuning frequency. That is, when the drive frequency is switched, the voltage level increases as the drive frequency approaches the tuning frequency, and the voltage level decreases as the drive frequency increases.

Therefore, when the drive frequency is switched from the high frequency to the low frequency and the switch operation information of the position indicator 2 is detected, the peak voltage can be detected if the start of the voltage level can be detected. Subsequent frequency switching processing and voltage measurement processing at these frequencies are unnecessary. This can be said algorithmically as follows. That is, when comparing the voltage level obtained by the currently applied drive frequency with the voltage level at the previously applied drive frequency, the voltage measurement operation is continued when the current voltage level is higher, and the previous time when the current voltage level is lower. The drive frequency is set as a tuning frequency, and the position of the position indicator 2 or switch operation information (information about which switch is operated) is detected from this tuning frequency, and the voltage measurement operation is completed. When determining the tuning frequency during the voltage measurement, as shown by the shaded area in FIG. 4, frequencies before and after the tuning frequency are given as drive frequencies, and whether this frequency is the true tuning frequency or not. Check if

As described above, the drive frequency is sequentially switched from the high frequency to the low frequency to measure the induced voltage, so that the voltage measuring operation after the peak voltage detection can be omitted,
Therefore, the induced voltage can be measured efficiently. Normally, in this type of device, the switch is not operated in most cases. Therefore, by setting the tuning frequency when the switch is not operated as the reference frequency αKH _Z , unnecessary voltage measurement operation when the switch is not operated is omitted. Therefore, the induced voltage can be measured more efficiently.

FIG. 5 is a flowchart showing the operation of the processing circuit 17, which summarizes the operation of detecting the position and switch operation information of the position indicator 2 described above.
Here, the processing of steps 50 to 54 is equivalent to the conventional processing shown in steps 60 to 64 of the flowchart of FIG. 6, and the full surface search processing (step 51) and the near search processing (step 51) according to the detection operation selection judgment of step 50. Step 5
3) is performed, and as a result, the area (area) in which the position indicator 2 is located is specified in each search process, and when the determination of area recognition is “Y” in step 52 and step 54, the position indication is performed in step 55. Precision position determination processing and switch identification processing of the container 2 are executed.

In the process of the switch 55, in order to detect the position of the position indicator 2 and the switch operation information,
Sequentially supplied every predetermined time the current in the driving frequency of αKH _Z ~εKH _Z as described above to the drive coil group 11, selects the highest driving frequency as a tuning frequency while providing a drive current of the selected tuning frequency The induced voltage in the peripheral 9 areas including the area where the position indicator 2 is located is measured. Then, the precise position and switch operation information are detected from the voltage distribution in the upper, lower, left and right regions of the region where the position indicator 2 is located.

When the precise position of the position indicator 2 is detected and the coordinate position can be calculated, step 5
After “Y” of “coordinate recognition” in step 6, step 57
In step 58, the output coordinate value is set in a buffer or the like, and in step 59, the switch operation information is output to the host device 18 together with the coordinate value.

In the above, the case where a plurality of frequencies are sequentially selected from the high frequencies has been described, but the selection order may be performed from the low frequency side. That is, after it is determined that the switch operation has been performed, the low frequency εKH _{Z is} followed by the αKH _{Z in} order.
_The driving frequency may be selected up to _Z.

[0026]

As described above, according to the present invention, the sum of the induced voltage measured last time and the sum of the induced voltage measured this time in the vicinity of the area where the position pointing device is located is set to a predetermined condition. And the switch operation information detection process is executed based on the comparison result, so that the operation information can be easily detected no matter what timing the switch is operated. When the process proceeds to the switch operation information detection process, the drive frequency of the current supplied to the drive coil group is sequentially selected from the high-frequency side or the low-frequency side of a plurality of different tuning frequencies, and the measured induced voltage Since one of the tuning frequencies is specified by detecting that the level is lower than the previously measured level, the switch operation information can be efficiently detected.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a digitizer according to the present invention.

FIG. 2 is a block diagram of a position indicator that constitutes the digitizer.

FIG. 3 is a diagram showing an induced voltage measurement region when detecting a position of a position indicator and switch operation information.

FIG. 4 is an explanatory diagram showing a detection order when detecting a position of a position indicator and switch operation information.

FIG. 5 is a flowchart showing an operation when detecting the position of the position indicator and the switch operation information.

FIG. 6 is a flowchart showing the operation of the conventional device when detecting the position of the position indicator and the switch operation information.

[Explanation of symbols]

 1 Tablet 2 Position Indicator 11 Drive Coil Group 12 Y Scanner Circuit 13 Drive Circuit 14 Sense Coil Group 15 X Scanner Circuit 16 Sense Circuit 17 Processing Circuit

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Hideaki Maruo 503-10 Shinanomachi, Totsuka-ku, Yokohama, Kanagawa Prefecture Graphtec Co., Ltd.

Claims (1)

[Claims] 1. A coordinate detection coil group including a tablet and a position indicator, wherein the tablet includes a coordinate detection coil group including a loop coil whose voltage state changes at least by a radio wave transmission / reception action with the position indicator, and the loop coil. A first tuning circuit which is provided with a detecting means for detecting a voltage state, and which has at least a coil and a capacitor, and which is tuned at a first tuning frequency; A second tuning circuit that tunes at a plurality of frequencies near the first tuning frequency, the pointing coordinate pointed by the position pointing unit and the position based on a change in the voltage state of the coordinate detection coil group. A digitizer for detecting operation information of an indicator, wherein the tab is determined based on the arrangement position of each loop coil forming the coordinate detection coil group. The area on the table is divided into a plurality of areas, and the sum of the induction voltage measured last time and the sum of the induction voltage measured this time in the vicinity of the area where the position indicator is located are determined under predetermined conditions. Comparison means for comparing, means for shifting to operation information detection processing for the position indicator according to the comparison result of this comparison means, and frequency of current supplied to the coordinate detection coil group when shifting to the detection processing Means for sequentially selecting from the high frequency side or the low frequency side of the plurality of tuning frequencies, and detecting the voltage level induced to the coordinate detection coil group for each selected frequency, And a means for specifying any one of the plurality of tuning frequencies by detecting that the voltage level is lower than the voltage level of the digitizer.