CN1292348C - Position detecting device - Google Patents
Position detecting device Download PDFInfo
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- CN1292348C CN1292348C CN 02142550 CN02142550A CN1292348C CN 1292348 C CN1292348 C CN 1292348C CN 02142550 CN02142550 CN 02142550 CN 02142550 A CN02142550 A CN 02142550A CN 1292348 C CN1292348 C CN 1292348C
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Abstract
The present invention relates to a position detecting device which can stably detect the coordinate values of an indication position, but is not influenced by external noise even containing many frequency components having the same harmonic frequency with a position indicator. In the state of selecting the same loop coil, at least two-time receiving and sending of the electromagnetic waves are continuously carried out by the position indicator (13); the phase difference of which the harmonic frequency of is smaller than one period on each-time receiving and sending signals is kept by a counting circuit (10) and a switch circuit (11) so that signals of the receiving signals in the loop coil are adjusted by phase positions and then used as wave detecting clock pulses. A synchronous wave detection circuit (5) detects the waves synchronously; successively, through equalization or addition, the external noise in the receiving signals is balanced out.
Description
Technical field
The present invention relates to be used for the position detecting device of figure and literal input computing machine.
Background technology
As existing this position detecting device, there have the spy to open on the clear 63-70326 communique to be disclosed.
In aforesaid position detecting device,, obtain the coordinate figure of the indicating positions that produces by its position indicator by between figure input card and position indicator, exchanging electric wave.In view of the above, select progressively a plurality of loop coils arranged side by side on the position probing direction of figure input card, emission is electric wave the time, receives the electric wave that the oscillatory circuit that is provided with from position indicator is launched again, obtains the coordinate figure of indicating positions by its received signal intensity distributions.
This position detecting device CRT watch-dog most as computer input device and as display device uses simultaneously.Because this CRT watch-dog is by the high-intensity magnetic field controlling electron beam, so emission forceful electric power magnetic noise.Therefore, be subjected in the position detecting device shown in aforementioned, the problem that what is called can not the stable detection coordinate figure is arranged from the noise effect of CRT watch-dog emission.
In this position detecting device, except the noise that is subjected to the CRT watch-dog, also be subjected to the electric wave influence that radio broadcasting office comes.
In order to relax the influence of this class extraneous noise at least, in aforesaid conventional example, in a loop coil, carry out the transmitting-receiving of continuous several times, reduce The noise by equalization.In addition, be provided with the bandpass filter of the frequency content that only is used for strong cohesiveness receipts target as receiving circuit.
When yet the frequency that the frequency content that comprises the electric wave that noise that comes from the CRT watch-dog or radio office come and figure input card should receive was consistent, it was difficult eliminating its influence with preceding method.
Summary of the invention
The purpose of this invention is to provide position detecting device, at the problems referred to above, even when the frequency content of extraneous noise is consistent with the frequency that should receive, also be difficult to be subjected to noise effect, stably detection coordinates value.
In the present invention, in order to reach aforementioned purpose, by comprising the position indicator of the resonant circuit of coil and capacitor at least, with be included in many loop coils that the position probing direction is set up in parallel, when position indicator is received and dispatched the electromagnetic wave of preset frequency, obtain in the position detecting device that the figure input card of the coordinate figure of the indicating positions that is produced by position indicator constitutes by the received signal level that in aforementioned many loop coils, takes place, it is characterized by, in the figure input card, be provided with following device, that is: the double at least transceiver controller spare that the electromagnetic wave of position indicator is received and dispatched under the state of selecting same loop coil; The phase differential control device that signal phase difference in each time transmitting-receiving when the double at least transmitting-receiving aforementioned electric magnetic wave is controlled; To carry out the same detecting circuit of synchronous detection to the signal that the received signal that takes place in the loop coil is carried out aforementioned phase control as the detection time clock; And at least twice electromagnetic transmitting-receiving that obtains according to aforementioned synchronous detection, calculate the mean value of level of at least two received signals or the signal level processing apparatus of aggregate values.
According to aforementioned formation, possess when double transmitting-receiving at least, be adjusted in the phase difference function of each time of signal that exchanges between position indicator and the figure input card.Obtain thus the signal level that obtains by these receiving and transmitting signals average or amount to during, can adjust phase differential so that cancel out each other The noise, the stable coordinate that not influenced by extraneous noise is detected becomes possibility.
Here, aforementioned phase differential control device can be realized by changing the electromagnetic transmitting-receiving start time each time, can realize with simple formation.
Description of drawings
Fig. 1 is the pie graph that the 1st embodiment of position detecting device of the present invention is shown.
Fig. 2 illustrates the concrete circuit diagram that constitutes an example of synchro detection circuit.
Fig. 3 is that synchro detection circuit that Fig. 2 is shown moves the oscillogram of an example.
Fig. 4 illustrates the concrete circuit diagram that constitutes an example of counting circuit.
Fig. 5 is the oscillogram of each several part signal one example when the part scanning motion of the present invention's the 1st embodiment is shown.
Fig. 6 is another the routine oscillogram of each several part signal when the part scanning motion of the present invention's the 1st embodiment is shown.
Fig. 7 is the schematic diagram of noise removing of the present invention.
Fig. 8 is all process flow diagrams of handling of position probing action of the 1st embodiment.
Fig. 9 is the processing flow chart that the part loop coil among Fig. 8 is selected the transmitting-receiving action.
Figure 10 is the pie graph that the 2nd embodiment of position detecting device of the present invention is shown.
Symbol description 1: position detection part; 2: select circuit; 3: transmitting-receiving change-over circuit 4: amplifying circuit; 5,20: synchro detection circuit; 6,21: integrating circuit; 7, the 22:AD translation circuit; 8:CPU; 9: oscillatory circuit; 10: counting circuit; 11: on-off circuit 12,23,24: frequency dividing circuit; 13,26: position indicator; 25: clock pulse generating circuit.
Embodiment
[the 1st embodiment]
(formation of the 1st embodiment)
Fig. 1 is the figure that position detecting device the 1st embodiment of the present invention is shown.
In Fig. 1, the 1st, position detection part, a plurality of, here be that 40 loop coils dispose as loop coil X1～X40 and loop coil Y1～Y40 separately in X-direction and Y direction.These loop coils are connected with the selection circuit 2 of selecting each loop coil.
The 9th, the preset frequency f that will launch from position detection part 1
oJust the oscillatory circuit that sends 32 times frequency.Oscillatory circuit 9 respectively with CPU8, counting circuit 10 and on-off circuit 11 connects.The output of counting circuit 10 is connected with on-off circuit 11.
The output of on-off circuit 11 is connected with the frequency dividing circuit 12 of frequency dividing ratio 1/32, and the output of this frequency dividing circuit 12 is connected with the transmitter side (T) of transmitting-receiving change-over circuit 3, the loop coil transmission frequency f that selects from position detection part 1
oAC magnetic field.In addition, the output of frequency dividing circuit 12 also is connected with detection clock pulse input terminal of synchro detection circuit 5.
CPU8 is transported to various control signals described later (information) respectively and selects circuit 2, transmitting-receiving change-over circuit 3, integrating circuit 6, AD translation circuit 7 and counting circuit 10.
Constitute the figure input card by the element of representing with these symbols 1～12.
In Fig. 1, the 13rd, position indicator, portion is provided with coil 14 within it, and a pressure sensor 15 and pen are pressed testing circuit 16.Coil 14 is connected with not shown capacitor, makes frequency f
oResonant circuit.Pen presses testing circuit 16 to constitute by the electronic circuit that comprises IC, and the simulating signal from a pressure sensor 15 is transformed to the time-division digital signal, and this digital signal is passed through coil 14 home position test sections 1.The action of this position indicator because for example open in the spy opens flat 5-313439 communique, is here omitted.
Fig. 2 illustrates the concrete formation of synchro detection circuit one example, is to use analog switch, operational amplifier and resistive element (R1, the circuit that crowd R2) knows.Fig. 3 is that synchro detection circuit that Fig. 2 is shown moves the oscillogram of an example.The detection time clock when positive half cycle, the noninverting output of input signal, the anti-phase output of input signal when negative half period.Thereby,, then can only take out frequency content, i.e. the frequency content of detection time clock as target if this output signal is carried out the certain hour integration.
Fig. 4 is the example that the concrete formation of counting circuit is shown, among the figure, and the 101st, counter, the 102nd, comparer, the 103rd, trigger circuit.
The time clock terminal of counter 101 is connected with oscillatory circuit 9, lead-out terminal Q
0～Q
5Input terminal A with comparer 102
0～A
5Connect.The input terminal B of comparer 102
0～B
5Be connected with CPU8, lead-out terminal is connected with the reseting terminal of trigger 103.The time clock terminal of trigger 103 is connected with CPU8, and the D terminal is connected with power supply (high level), and the Q lead-out terminal is connected with the reseting terminal and the on-off circuit 11 of counter 101.
In aforementioned formation, if the trigger pulse input trigger 103 that comes from CPU8 rises thereon then that lead-out terminal Q starts working on the edge, the counting action of the oscillator signal of counter 101 starting oscillation circuit 9.Input terminal B at comparer 102
0～B
5On set predetermined value from CPU8 input in advance, if count value unanimity that should value sum counter 101, then the lead-out terminal of comparer 102 is started working.Because in the time limit of this rising edge, trigger 103 resets, so the Q of trigger 103 output, that is, the output of counting circuit 10 forms and the pulse signal of the value of only setting from CPU8 (0 to 31 scope) to the suitable width of the oscillator signal gate time of oscillatory circuit 9.
(action of the 1st embodiment)
At first, being used for comprehensive scanning motion and conventional device situation that detection position indicator 13 substantially is in position testeding outleting part 1 which position similarly carries out.
Each 40 loop coil whole of X-direction and Y direction are changed on this comprehensive scanning motion limit in proper order, and transmitting-receiving electric wave in limit detects the signal level that whether receives greater than predetermined value, then, the loop coil (crest line circle) of signal level maximum is taken a sample.
Because this comprehensive scanning motion is used for initial detection position indicator 13 and is in which position substantially, so the influence that extraneous noise produces does not become problem.Thereby during this comprehensive scanning motion, CPU8 controls counting circuit, so that make on-off circuit 11 often be in conducting state, specifically, trigger pulse is not supplied with counting circuit 10.
Secondly, illustrate by the part scanning motion after the general location of above-mentioned comprehensive scanning motion understanding position indicator 13.
Fig. 5, Fig. 6 are the signal waveforms of each several part when the part scanning motion of present embodiment is shown, Fig. 5 is same when being used for explanation and comprehensive scanning motion, trigger pulse is not supplied with counting circuit 10, the on-off circuit 11 normal conducting states that keep, do not manifest the oscillogram of doing the time spent originally, the oscillogram when Fig. 6 is the actual act that produces by the present invention.
At Fig. 5, among Fig. 6, a is from the next transmission signal of the loop coil of position detection part 1, b is the received signal from position indicator 13, C is the output signal from amplifying circuit 4, d is a detection clock pulse signal of supplying with synchro detection circuit 5, and e is the trigger pulse from CPU8 input counting circuit 10.In addition, f is the noise that adds from the CRT watch-dog, and this noise contains frequency f more
oComposition.In addition, g is the output signal of synchro detection circuit 5, and h is the output signal of integrating circuit 6.These each signals a～h is corresponding with Fig. 1 (a)～(h) (wherein, except the f) respectively.
Near when Fig. 5, Fig. 6 illustrate position indicator and be in the loop coil X7 directions X part scanning motion.CPU8 as described later shown in, for changing in proper order as 5 loop coil X5～X9 limits, front and back at center with loop coil X7, detection is carried out to the signal level of the position indicator 13 of each loop coil in the limit.At this moment, 1 loop coil is carried out 2 transmitting-receivings, the mean value by 2 signal levels (output valve of AD translation circuit 7) carries out coordinate Calculation.
Here, 1 time the transmitting-receiving have 3 action step (during).
At first, CPU8 selects loop coil X7 in selecting circuit 2, simultaneously transmitting-receiving change-over circuit 3 is transformed into transmitter side (T).Thus, from the signal of loop coil X7 to position indicator 13 transmission frequency fo.
Secondly, CPU8 selects loop coil X5 in selecting circuit 2, simultaneously the transmitting-receiving change-over circuit is transformed into receiver side (R).Thus, detect from the signal of position indicator 13 from loop coil X5, via synchro detection circuit 5 input integral circuit 6.
CPU8 is transformed into the side (N) that neither transmission does not also receive to transmitting-receiving change-over circuit 3.Thus, from the signal of position indicator 13 input integral circuit 6 not, so integrating circuit 6 keeps certain output valve.CPU8 makes 7 actions of AD translation circuit therebetween, and its output valve is read as signal level.
CPU8 moves equally, selects loop coil X7 when sending, and selects loop coil X5 during reception, receives and dispatches action once more.Signal level detection to loop coil X5 finishes thus.
CPU8 also is used for the action of signal level detection with aforementioned execution similarly to loop coil X6～9.Here omit, yet CPU8 proceeds the part scanning motion of aforementioned directions X, and for 5 the ring coils dos action (the part scanning motion of Y direction) as hereinbefore that at the crest line circle with the Y direction is the Y direction at center.
The noise that comes from the CRT watch-dog comprises frequency f o composition more, under the situation of example shown in Figure 5, occurs noise spike as shown in figure in the detection output signal g.This noise spike adds up by integrating circuit 6, since influential to each signal level that detects, so can not correctly obtain the indicating positions of position indicator 13.
Secondly, according to actual act of the present invention, the part scanning motion during promptly for the trigger pulse e that supplies with counting circuit 10 from CPU8 illustrates with Fig. 6.
At Fig. 6, per 1 transmitting-receiving of each loop coil stops, with the state of transmitting-receiving change-over circuit 3 as N during, CPU8 is set in predefined optimum value to counting circuit 10.Then, CPU8 output trigger pulse is to counting circuit 10.
Because counting circuit 10 as Fig. 4 illustrates, is imported this trigger pulse, so the pulse signal of the suitable width of clock pulses number of output and aforementioned preset value.This pulse signal input switching circuit 11, only during this pulsewidth, on-off circuit 11 becomes off state, and the action of frequency dividing circuit 12 only stops in the meantime.That is between the 1st time transmitting-receiving and the 2nd transmitting-receiving only delay suitable with aforementioned pulsewidth takes place.
Because be to counting from the time clock of oscillatory circuit 9, so form the scope in 1 cycle of frequency f o this time delay in 0～31 scope.This action is one of feature of the present invention.
As the optimum value of setting at counting circuit 10 from aforesaid CPU8, be taken at the value that the 1st time and the 2nd time of transmitting-receiving just in time forms anti-phase relation by the phase relation between CRT noise e and the detection time clock d, the polarity of the CRT noise that occurs in the output of synchro detection circuit 5 can make on the contrary the 1st time and the 2nd time of transmitting-receiving.Thereby, if, the output valve of AD translation circuit 7 is done equalization or addition, then make and offset the CRT noise effect and become possibility according to the output of these synchro detection circuits 5, can calculate correct coordinate figure
Fig. 7 illustrates about by the time between the 1st transmitting-receiving and the 2nd transmitting-receiving is adjusted, and can offset the principle of noise effect.
Fig. 8 illustrates the flow process of all processing of the position probing action of above-mentioned the 1st embodiment, and Fig. 9 illustrates the flow process that part loop coil among Fig. 8 selects the signal transmitting and receiving action to handle (wherein, owing to be identical to the action of Y direction with directions X, so omission).At Fig. 9, the transmitting-receiving number of times the when number of the loop coil of selecting when i is illustrated in and sends (crest line circle), the number of the loop coil of selecting when k represents to receive, m represent that same receiving coil is selected, the transmitting-receiving number of times when n represents to change receiving coil.
(expansion of the 1st embodiment)
In present embodiment, adjust by clock pulse count being carried out the aforementioned time, yet also can use other method.As the synchro detection circuit analog switching circuit reverse of polarity, however also can be with analog multiplier etc.
In present embodiment, count with the time clock of transmission frequency fo32 frequency doubly, but be not limited to this, also can be with the time clock of other frequency.
In present embodiment, as extraneous noise the situation of CRT watch-dog has been illustrated its effect, yet, even near the radio broadcasting office that the frequency close with fo sends, also can be by eliminating the influence of radiowave with the identical principle of above-mentioned explanation.In addition, if in addition understand noise source in advance, it also is possible then eliminating the noise effect that contains a plurality of frequency f o compositions.
In present embodiment, only the time of carrying out is adjusted when the 1st transmitting-receiving stops, yet also can carry out the 1st time and the 2nd two sides.
In present embodiment, carry out the transmitting-receiving equalization 2 times for 1 loop coil, yet, also can carry out equalization 4 times to it.When carrying out 4 times, also can receive and dispatch and carry out aforesaid time adjustment when stopping at the 1st time and the 3rd time, in addition, also can adjust at every turn.
In present embodiment, adjust length as the time between the 1st time and the 2nd time and should set the value of obtaining in advance, yet, when dropping into, tests when setting fully power supply, and also can set and automatically obtain the value that noise effect becomes hour.
[the 2nd embodiment)
(formation of the 2nd embodiment)
Figure 10 is the 2nd embodiment that position detecting device of the present invention is shown, and component part identical with the 1st embodiment among the figure is represented with prosign.
The dissimilarity of the formation of present embodiment and the 1st embodiment is: synchro detection circuit is provided with 2 systems to the acceptance division of AD translation circuit, and the detection time clock of skew 90 degree phase places is provided on synchro detection circuit separately.
That is, in Figure 10, the 20th, synchro detection circuit, its input is connected in the output of amplifying circuit 4, and output is connected with integrating circuit 21.The input of this integrating circuit 21 is connected with AD translation circuit 22, and then, the output of this AD translation circuit 22 is connected with CPU8.
The 23rd, the frequency dividing circuit of frequency dividing ratio 1/16, its input is connected with the output of on-off circuit 11, and its output is connected with the frequency dividing circuit 24 and the clock circuit 25 of frequency dividing ratio 1/2.The output of this frequency dividing circuit 24 is connected with the transmitter side (T) of transmitting-receiving change-over circuit 3, and is same with the 1st embodiment, and the signal of frequency f o is supplied with position detection part 1.
Constitute the figure input card by element with these symbol 1～11,20～25 expressions.
In Figure 10, the 26th, position indicator, portion is provided with coil 27 within it, is connected with this coil 27, is used for and the not shown capacitor of frequency f o resonance and the variable condenser 28 that makes electrostatic capacitance change according to the pen pressure.Variable condenser 28 also is connected with coil 27, presses according to pen, and resonance frequency changes a little.
(action of the 2nd embodiment)
In present embodiment, because press according to pen, the signal phase of reception changes, so obtain separately signal level by the acceptance division of aforesaid 2 systems, obtains the phasing degree of received signal by its ratio, thus, obtains the pen that is added on the position indicator 26 and presses.Because open in the described communique of prior art or its relevant application, here omit for these actions.
Even under the situation of this embodiment, from also carrying out comprehensive scanning motion at first, obtain the position indicator general location and begin, it is identical with the situation of the 1st embodiment carrying out part scanning motion this point.Only be with the 1st embodiment difference: in Fig. 6, synchronous detection output, integration output exist in other 1 system.
Even in present embodiment, also set the optimum value that counting circuit 10 is presetted from CPU8, if then similarly export trigger pulse with the situation of the 1st embodiment, the pulse signal of counting circuit 10 output and the suitable width of clock pulses number of aforementioned default definite value then.This pulse signal is input to on-off circuit 11, and only during this pulsewidth, on-off circuit 11 becomes off state, and the action of frequency dividing circuit 23,24 is only stopping during this period.Produce the slightly delay suitable between the transmitting-receiving of i.e. the 1st time transmitting-receiving and the 2nd time with aforementioned pulsewidth.
Therefore, same with the situation of the 1st embodiment, because the phase relation between CRT noise and the detection time clock is sent on the 1st time and the 2nd time in transmitting-receiving and is just in time formed anti-phase relation, so the CRT noise polarity that occurs in the output of two synchro detection circuits 5,20 can be anti-phase in the 1st time and the 2nd time of transmitting-receiving.
Therefore,,, make and offset the CRT The noise and become possibility, make the phasing degree of calculating correct coordinate figure and received signal become possibility the output valve equalization or the addition of AD translation circuit 7,22 if according to the output of these synchro detection circuits 5,20.
It is identical with the situation of the 1st embodiment basically that all flow processs of handling of the position probing of the 2nd above-mentioned embodiment action and part loop coil are selected flow process that the signal transmitting and receiving action handles.
(expansion of the 2nd embodiment)
In present embodiment, carry out the aforementioned time by clock pulse count and adjust, yet, also can use other method.As the synchro detection circuit analog switching circuit reverse of polarity, but also can be with analogue multiplier etc.
In present embodiment, as extraneous noise, the situation of CRT watch-dog is illustrated its effect, yet, using near the radio broadcasting office that sends with the fo close frequencies, also can be by using the influence of eliminating radiobeam with the identical principle of above-mentioned explanation.Even in addition,, also be possible to the noise removing influence that contains frequency f o composition if understand noise source in advance more.
In present embodiment, only the time of carrying out is adjusted when the 1st transmitting-receiving stops, yet also can carry out the 1st time and the 2nd both sides it.
In present embodiment, carry out 2 transmitting-receivings about 1 loop coil, equalization, however also can carry out equalization 4 times to it.Carrying out under 4 times the situation, also can be when the 1st time and the 3rd transmitting-receiving stop the time of carrying out adjust, carry out good in addition at every turn.
In present embodiment,, should set the value of obtaining in advance as the length that the time during the 1st time and the 2nd time is adjusted, yet, when power supply drops into during with regard to whole setting with regard to, test, also can set automatically obtaining the value that noise effect becomes minimum.
(effect of invention)
Just as described above, according to the present invention, carry out at least continuously 2 times the position indicated The electromagnetic wave transmitting-receiving of device is adjusted by the time of carrying out between these transmitting-receivings simultaneously, makes the 1st time The noise polarity of sneaking into during reception and when receiving for the 2nd time is anti-phase, and making to offset becomes possibility. Thus, Even to comprising consumingly and the same frequency content of the resonant frequency of the position indicator that is difficult to remove Extraneous noise also can provide and not affected by it, stably detect the position of indicating positions coordinate figure Detection device.
Claims (2)
1. position detecting device, at the position indicator that comprises the resonant circuit of coil and capacitor by outfit at least, and upwards be set side by side with a plurality of loop coils and to the electromagnetic wave of position indicator transmitting-receiving preset frequency the time, obtain in the position detecting device that the figure input card of the coordinate figure of the indicating positions that is produced by position indicator forms by the level of the received signal that in described a plurality of loop coils, takes place the position detection side, it is characterized in that
In the figure input card, be provided with:
Under the state of selecting same loop coil, the double at least transceiver controller spare that the electromagnetic wave of position indicator is received and dispatched,
The phase differential control device that signal phase difference in each time transmitting-receiving during to the described electromagnetic wave of double at least transmitting-receiving is controlled,
The signal that will carry out described phase control to the received signal that takes place in the loop coil carries out the synchro detection circuit of synchronous detection as the detection time clock, and
According at least twice electromagnetic transmitting-receiving that described synchronous detection obtains, calculate the mean value of at least two received signal levels or the signal level processing apparatus of aggregate values.
2. position detecting device according to claim 1 is characterized in that, described phase differential control device changes the start time of electromagnetic wave transmitting-receiving one by one.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02142550 CN1292348C (en) | 2002-09-24 | 2002-09-24 | Position detecting device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02142550 CN1292348C (en) | 2002-09-24 | 2002-09-24 | Position detecting device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1485736A CN1485736A (en) | 2004-03-31 |
| CN1292348C true CN1292348C (en) | 2006-12-27 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 02142550 Expired - Fee Related CN1292348C (en) | 2002-09-24 | 2002-09-24 | Position detecting device |
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| CN (1) | CN1292348C (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4709674B2 (en) * | 2006-03-23 | 2011-06-22 | 株式会社ワコム | Position detection apparatus and computer |
| CN102650921A (en) * | 2011-02-25 | 2012-08-29 | 太瀚科技股份有限公司 | Electromagnetic induction system and antenna circuit layout method thereof |
| KR102366071B1 (en) * | 2014-10-06 | 2022-02-23 | 가부시키가이샤 와코무 | Detection device, input device and detection method |
| CN107111379B (en) * | 2015-01-30 | 2021-03-16 | 株式会社和冠 | Position indicator |
| CN106775142B (en) * | 2015-12-31 | 2019-10-01 | 深圳市汇顶科技股份有限公司 | Capacitance sensing circuit |
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2002
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| CN1485736A (en) | 2004-03-31 |
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Address after: Saitama Prefecture, Japan Patentee after: Wacom Co., Ltd. Address before: Saitama Prefecture, Japan Patentee before: Wacom Co., Ltd. |
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