JP6899266B2 - Capacity detection method - Google Patents

Description

The present invention relates to a capacitance detection method using a touch panel for detecting a capacitance or a capacitance change between a plurality of electrodes and a detection target.

Patent Document 1 discloses a capacitance detection method using a touch panel for detecting a capacitance or a capacitance change between a plurality of electrodes and a detection target.

In the capacitance detection method disclosed in Patent Document 1, the touch panel includes a plurality of detection electrodes arranged so as to be spaced apart from each other in a matrix. Then, a sense line is coupled to each of the detection electrodes. The sense line coupled to each of the detection electrodes is connected to the readout circuit.

In the capacitance detection method using the touch panel configured in this way, the signal corresponding to the capacitance between each detection electrode and the detection target is read out to the readout circuit through the corresponding sense line. Then, the distribution of the capacitance or the change in capacitance on the touch panel is detected.

Japanese Unexamined Patent Publication No. 2015-32234 (published on February 16, 2015)

However, in the prior art as described above, in order to detect the capacitance or the distribution of the capacitance change on the touch panel, the sense lines must be drawn from all the detection electrodes of the touch panel to the readout circuit. Therefore, when looking at the increase in size of the touch panel, the wiring resistance of the sense line increases, and the number of channels of the readout circuit (the number of sense lines) is proportional to the multiplication result of the number of rows and the number of columns of the detection electrode. Therefore, there is a problem that the configuration becomes enormous and the configuration of the touch panel system becomes complicated.

In order to solve this problem, for example, one sense line is arranged for each of a plurality of detection electrodes arranged in a row, and a switch is provided between the sense line and each detection electrode. It is conceivable to reduce the number of sense lines.

However, there arises a problem that switching noise caused by the on / off operation of the switch provided between the sense line and each detection electrode affects the detection result such as capacitance. Since the switching noise is generally constant noise, the influence on the detection result can be reduced by the calibration process of subtracting the reference data from the detection data. However, if the influence of the switching noise is not constant, the influence of the switching noise on the detection result cannot be reduced even if the above calibration process is performed.

One aspect of the present invention is a capacitance detection method capable of reducing the influence of switching noise caused by the on / off operation of a switch provided between the sense line and each detection electrode on the detection result such as capacitance. The purpose is to realize it.

In order to solve the above problems, the capacitance detection method according to one aspect of the present invention is a plurality of electrodes arranged in a matrix, with a plurality of first signal lines arranged in the first direction of the matrix. to charge a plurality of electrodes in which a plurality of first switching element is formed between a plurality of electrodes, along a plurality of second signal lines arranged in the second direction crossing the first direction, wherein A drive step of driving in parallel based on a code sequence through a plurality of second switch elements formed between the second signal line and the plurality of electrodes, and a linearity based on the charges charged to the plurality of electrodes by the drive step. a sum signal, and a read step of reading along the first signal line via the first switch element, for charging said plurality of electrodes, the plurality of electrodes, along the second signal line the The inverting drive step of driving in parallel based on the inverting code sequence through the second switch element and the inverting linear sum signal based on the charges charged to the plurality of electrodes by the inverting driving step are transmitted to the first switch element via the first switch element . An inverting read-out step of reading along one signal line and a detection step of subtracting the inverting linear sum signal from the linear sum signal to detect a capacitance distribution or a capacitance change distribution between the plurality of electrodes and a detection target. It is characterized by inclusion.

In order to solve the above problems, another capacitance detection method according to one aspect of the present invention is a plurality of electrodes arranged in a matrix, and a plurality of first signal lines arranged in the first direction of the matrix. A non-driving read-out step of reading out a non-driving linear sum signal based on the electric charge of a plurality of electrodes on which a plurality of first switch elements are formed along the first signal line, and for charging the plurality of electrodes. A driving step of driving the plurality of electrodes in parallel based on a code sequence, a reading step of reading out a linear sum signal based on the charges charged to the plurality of electrodes by the driving step along the first signal line, and the above-mentioned It is characterized by including a detection step of subtracting the non-driven linear sum signal from the linear sum signal to detect a capacitance distribution or a capacitance change distribution between the plurality of electrodes and a detection target.

In order to solve the above problems, another capacitance detection method according to one aspect of the present invention is a plurality of electrodes arranged in a matrix, and a plurality of first signals arranged in the first direction of the matrix. A reference driving step of driving the plurality of electrodes in parallel based on a code sequence in a reference state where there is no measurement target in order to charge the plurality of electrodes in which a plurality of first switch elements are formed between the wires and the reference. A reference reading step of reading out a reference linear sum signal based on the charges charged to the plurality of electrodes by the driving step along the first signal line, and the above-mentioned step of charging the plurality of electrodes in a measurement state for detecting a measurement target. A measurement drive step in which a plurality of electrodes are driven in parallel based on the code sequence, and a measurement readout step in which a measurement linear sum signal based on the charges charged in the plurality of electrodes by the measurement drive step is read out along the first signal line. A part of the plurality of electrodes is surrounded and shielded by an AC ground electrode having an AC grounded potential so as not to have an AC component so as not to be affected by the measurement target. Based on the subtraction result obtained by subtracting the reference linear sum signal from the measured linear sum signal and the code sequence, the capacitance distribution or the capacitance change distribution between the plurality of electrodes and the detection target is obtained. It is characterized by further including a decoding step of decoding and a correction step of correcting the decoded capacitance distribution or capacitance change distribution based on the decoding result of the portion where the reference electrode is arranged among the plurality of electrodes. To do.

According to one aspect of the present invention, it is possible to reduce the influence of switching noise caused by the on / off operation of the switch provided between the sense line and each detection electrode on the detection result such as capacitance. Play.

It is a circuit diagram which shows the structure of the touch panel system which concerns on Embodiment 1. FIG. It is a timing chart which shows the scanning of the touch panel system. (A) to (c) are diagrams for explaining the capacity estimation calculation by the touch panel system. It is a figure for demonstrating the desired component and noise component of the data acquired by the touch panel system. (A) to (c) are diagrams for explaining the influence of switching noise at the time of reading by the differential amplifier provided in the touch panel system. It is a figure for demonstrating the capacity detection method by the said touch panel system. It is a figure for demonstrating the capacity detection method by the touch panel system which concerns on Embodiment 2. It is a figure for demonstrating the capacity detection method by the touch panel system which concerns on Embodiment 3. It is a circuit diagram which shows the structure of the touch panel system which concerns on Embodiment 4. It is a figure for demonstrating the capacity detection method by the touch panel system which concerns on Embodiment 4. It is a figure which shows the driving / decoding operation example using the M matrix which concerns on Embodiment 4. It is a figure which shows the other drive / decoding operation example using the said M matrix. It is a figure which shows still another drive / decoding operation example using the said M matrix. It is a figure which shows still another drive / decoding operation example using the said M matrix. It is a figure which shows the driving / decoding operation example using the Hadamard matrix which concerns on Embodiment 5. It is a figure which shows the other drive / decoding operation example using the said Hadamard matrix. It is a figure which shows still another driving / decoding operation example using the said Hadamard matrix. It is a figure which shows still another driving / decoding operation example using the said Hadamard matrix. (A) to (b) are diagrams showing examples of capacity detection results according to the fifth embodiment. It is a circuit diagram which shows the structure of the touch panel system which concerns on Embodiment 6. It is a circuit diagram which shows the structure of the touch panel system which concerns on Embodiment 7.

Hereinafter, embodiments of the present invention will be described in detail.・ ・ ・
[Embodiment 1]
FIG. 1 is a circuit diagram showing the configuration of the touch panel system 1 according to the first embodiment. The touch panel system 1 includes a touch panel 2 and a touch panel controller 3 that controls the touch panel 2.

The touch panel 2 has K (multiple K) drive lines DL <0> to DL <K-1> (second signal line) intersecting each other, and M (multiple M) sense lines SL <0. > ~ SL <M-1> (first signal line), K drive lines DL <0> ~ DL <K-1> and M sense lines SL <0> ~ SL <M-1> It is provided with (K × M) detection electrodes E (electrodes) arranged in a matrix corresponding to the intersection with.

On the touch panel 2, K drive control lines DS <0> to DS <K-1> and K sense control lines SS <0> to SS <K-1> are provided on each drive line DL <0>. It is arranged corresponding to ~ DL <K-1>. A drive switch element DT (second switch element) is formed between each detection electrode E and the corresponding drive line. A sense switch element ST (first switch element) is formed between each detection electrode E and the corresponding sense line. The drive switch element DT and the sense switch element ST are composed of transistors. The gate of each drive switch element DT is coupled to the corresponding drive control line. The gate of each sense switch element ST is coupled to the corresponding sense control line.

The touch panel 2 is provided to detect the capacitance or the change in capacitance between each detection electrode E and a detection target such as a finger or a pen.

The touch panel controller 3 includes a drive circuit 4 connected to K drive lines DL <0> to DL <K-1>, and K drive control lines DS <0> to DS <K-1> and K lines. To the switch element control circuit 8 connected to the sense control lines SS <0> to SS <K-1>, the plurality of read circuits 5 connected to the sense lines adjacent to each other, and the output of each read circuit 5. Based on this, it has a detection circuit 6 for detecting a capacitance or a capacitance change between each detection electrode E and a detection target.

Each readout circuit 5 has a differential amplifier 7 that amplifies the difference between the outputs of the sense lines adjacent to each other, between one input and one output of the differential amplifier 7, and between the other input and the other output. It has a pair of integrated capacitance Cint provided between. The read circuit 5 may have a switch (not shown) for resetting the state of the differential amplifier 7 by short-circuiting one terminal and the other terminal of the integrated capacitance Cint.

(Operation of touch panel system 1)
The touch panel system 1 configured in this way operates as follows.

First, the switch element control circuit 8 turns on (K × M) drive switch element DTs via K drive control lines DS <0> to DS <K-1>, and K sense control lines. The (K × M) sense switch elements ST are turned off via SS <0> to SS <K-1>. Then, the drive circuit 4 drives K drive lines DL <0> to DL <K-1> in parallel based on the code sequence of N rows and K columns, and drives each detection electrode E through each drive switch element DT. For example, it charges or discharges to the power supply voltage or the ground potential.

Next, the switch element control circuit 8 turns off (K × M) drive switch element DTs via K drive control lines DS <0> to DS <K-1>, and sets each detection electrode E. Make it floating. After that, the switch element control circuit 8 turns on (K × M) sense switch elements ST via K sense control lines SS <0> to SS <K-1>.

Then, each read-out circuit 5 amplifies the difference of the linear sum signal based on the charge of each detection electrode E read out along the adjacent sense line via the turned-on sense switch element ST. Next, the detection circuit 6 has a capacitance or a capacitance between each detection electrode E of the touch panel 2 and the detection target based on the inner product calculation of the difference between the linear sum signals output from each readout circuit 5 and the code sequence. Detect changes. After that, the detection circuit 6 detects the position of the detection target on the touch panel 2 based on the detected capacitance or the capacitance change.

(Reduction of switching noise itself)
FIG. 2 is a timing chart showing scanning of the touch panel system 1. It is also possible to reduce the switching noise itself by making the number of rising edges and falling edges of each signal the same before holding the sample.

As a method of reducing switching noise, there are a method of providing a dummy switch and applying a control signal of polarity inversion, and a method of making the number of rising edges and the number of falling edges shown in FIG. 2 the same. Even if it is used, the switching noise itself may not be sufficiently suppressed. Even in such a case, the influence of switching noise can be reduced by using the capacity estimation calculation technique of the present embodiment described later.

(Mixing of switching noise in capacitance estimation calculation during parallel drive)
3A to 3C are diagrams for explaining the capacity estimation calculation by the touch panel system 1. In the capacity estimation calculation during parallel drive by the touch panel system 1, as shown in FIGS. 3 (a) and 3 (c), a linear sum signal obtained by parallel drive using an M-sequence (Maximum length sequence) matrix M. The capacity distribution matrix C is obtained by multiplying the matrix D by the inverse matrix M ^{-1 of the M-sequence matrix M.}

However, when the switching noise caused by the on / off operation of the sense switch element ST and the drive switch element Dt is mixed in the linear sum signal based on the charge of each detection electrode E, the switching noise is as shown in FIG. 3 (b). There is a problem that the matrix N is mixed and the influence of switching noise N * M- ^{1 is mixed in the decoding result.}

FIG. 4 is a diagram for explaining a desired component and a noise component of the data acquired by the touch panel system 1. Let Cr be the C matrix of the calibration capacitance distribution in the reference state in which the touch of the touch panel 2 to be detected does not exist, and let Nr be the noise matrix when acquiring the reference data in the reference state. Then, the C matrix of the capacitance distribution in the measurement state where the touch exists is Ct, the noise matrix at the time of acquiring the measurement target data is Nt, the code sequence for dlife is M, and the decoding code (inverse matrix) is M ^-1. And. Then, the capacity estimation calculation for obtaining the reference data in the reference state is represented by (Equation 1) shown in FIG. 4, and the capacity estimation calculation for obtaining the measurement data in the measurement state is represented by (Equation 2) shown in FIG. ..

In order to reduce the influence of switching noise, as shown in (Equation 3) of FIG. 4, reference data is subtracted from the measurement data for calibration. When the noise matrices Nt and Nr are random noise, the influence of the term (Nt-Nr) on the right side of (Equation 3) can be reduced by averaging processing such as increasing the number of measurements. Further, even if the noise matrices Nt and Nr are not random noise and cannot be reduced by the averaging process, when Nt = Nr, the influence of the switching noise can be reduced by the calibration process.

However, when the noise matrices Nt and Nr are not random noise and the relationship is Nt ≠ Nr, there arises a problem that the effect of suppressing switching noise cannot be expected by either the averaging process or the calibration process.

(Amplifier output during differential reading)
5 (a) to 5 (c) are diagrams for explaining the influence of switching noise at the time of reading by the differential amplifier 7 provided in the touch panel system 1. FIG. 5A shows a state at the time of resetting the differential amplifier 7, and FIG. 5B shows a state at the time of integration of the differential amplifier 7. The capacitances C1p, C2p, C1m, and C2m correspond to the capacitances formed on the detection electrode E shown in FIG. The parasitic capacitance Cp1 and the noise capacitance Cc1 forming a noise charge mixing path due to switching noise are coupled to the sense line SL <0>. Then, the parasitic capacitance Cp2 and the noise capacitance Cc2 are coupled to the sense line SL <1>. The capacitances C1p and C2p are driven by a symbol (+1). The capacitances C1m and C2m are driven by the reference numeral (-1). From the charge conservation law corresponding to the sense line SL <0> coupled to the non-inverting input terminal of the differential amplifier 7, (Equation 4) of FIG. 5 (c) is established. From the charge conservation law corresponding to the sense line SL <1> coupled to the inverting input terminal of the differential amplifier 7, (Equation 5) of FIG. 5 (c) is established. As a result, (Equation 6) and (Equation 7) are derived.

Here, Cint is the integrated capacitance, C1p and C2p are the capacitances formed by the detection electrode E driven by the code (+1), and C1m and C2m are the detection electrodes driven by the code (-1). It is the capacitance formed by E. Cp1 and Cp2 are parasitic capacitances, and Cc1 and Cc2 are noise capacitances that form a noise charge mixing path. Vc is the common voltage and Vd is the drive voltage. Vd2 is the switching noise voltage, ΔV is the input common shift voltage, and Vout is the output voltage.

In (Equation 7), the component related to (−ΔV), the component related to (+ ΔV), and the component related to (-(Cp1-Cp2) ΔV + (Cc1-Cc2) (Vd2-ΔV)) are undesired components ( The error component), and the remaining component is the desired component. In the case of Vd >> ΔV, the component related to (−ΔV) and the component related to (+ ΔV) have a small effect because they are smaller than the desired component, but (-(Cp1-Cp2) ΔV + (Cc1-Cc2)) The component related to Vd2-ΔV)) may affect a desired component when the values of (Cp1-Cp2) and (Cc1-Cc2) are large.

For simplification, if Vd >> ΔV and Cp1 = Cp2, (Equation 7) can be approximated to (Equation 8). Even if the desired component of ((C1p-C2p)-(C1m-C2m)) Vd in (Equation 8) does not change and Cc1, Cc2, and Vd2 do not change, the denominator of (Equation 6) changes. Therefore, the undesired component (noise component) of (Cc1-Cc2) (Vd2-ΔV) may change.

This means that even if the switching noise itself (caused by Cc1, Cc2, Vd2) does not change, the capacitance C1p, C1m, C2p, C2m changes depending on the measurement target (touch operation), resulting in switching noise. It shows that the effects can change. Further, since this switching noise is not random noise, there arises a problem that the noise suppression effect by the averaging process cannot be expected.

(Capacity estimation calculation according to the first embodiment)
FIG. 6 is a diagram for explaining a capacity detection method by the touch panel system 1. In order to solve the above problem, the capacity estimation calculation according to the first embodiment is a plurality of detection electrodes E arranged in a matrix, and a plurality of sense lines SL <0> ... SL <arranged in the first direction of the matrix. A driving step of driving a plurality of electrodes E in parallel based on a code sequence M in order to charge a plurality of electrodes E in which a plurality of sense switch elements ST are formed between the M-1> and a plurality of the driving steps. A read-out step of reading out a linear sum signal (normal drive measurement value Drp · Dtp) based on the electric charge charged in the electrode E along a plurality of sense lines SL <0> ... SL <M-1>, and the plurality of electrodes. An inversion drive step in which the plurality of electrodes E are driven in parallel based on an inversion code sequence (-M) to charge E, and an inversion linear sum signal based on the charges charged in the plurality of electrodes E by the inversion drive step. The inverting read step of reading (reversing drive measurement values Drn · Dnt) along the sense lines SL <0> ... SL <M-1> and the inverting linear sum from the linear sum signal (normal drive measurement values Drp · Dtp). It includes a detection step of subtracting a signal (reversal drive measurement value Drn · Dnt) to detect a capacitance distribution or a capacitance change distribution between the plurality of electrodes E and a detection target.

When a plurality of electrodes E are driven in parallel based on the code sequence M in the reference state, normal driving noise Nrp is generated as shown in (Equation 9) of FIG. Then, when the parallel drive is performed based on the inversion code sequence (−M), the inversion drive noise Nrn is generated. Next, the reverse drive measurement value Drn is subtracted from the normal drive measurement value Drp in the reference state as shown in (Equation 11).

After that, when the plurality of electrodes E are driven in parallel based on the code sequence M in the measurement state, normal drive noise Ntp is generated as shown in FIG. 5 (Equation 12). Then, when the parallel drive is performed based on the inversion code sequence (−M), the inversion drive noise NTn is generated. Next, the reverse drive measurement value Dtn is subtracted from the normal drive measurement value Dtp in the measurement state as shown in (Equation 14).

here,
ΔV∝ ((C1p-C1m) + (C2p-C2m)) Vd + (Cc1 + Cc2) Vd2,
Because it is
| (Cc1 + Cc2) Vd2 | >> | ((C1p-C1m) + (C2p-C2m)) Vd |,
When
Nrp ≒ Nrn, and Ntp ≒ Ntn,
It becomes.

Therefore, the approximate expression of (Equation 15) in FIG. 6 is established.

In this way, by subtracting the reverse drive measurement value Drn from the normal drive measurement value Drp in the reference state, the normal drive noise Nrp in the reference state and the reverse drive noise Nrn are canceled out. Then, by subtracting the reverse drive measurement value Dtn from the normal drive measurement value Dtp in the measurement state, the normal drive noise Ntp in the measurement state and the reverse drive noise Ntn are canceled out.

[Embodiment 2]
Other embodiments of the present invention will be described below with reference to FIG. For convenience of explanation, the same reference numerals will be added to the members having the same functions as the members described in the above-described embodiment, and the description thereof will be omitted.

FIG. 7 is a diagram for explaining a capacity detection method by the touch panel system according to the second embodiment. The capacity estimation calculation according to the second embodiment is between a plurality of electrodes E arranged in a matrix and between a plurality of sense lines SL <0> ... SL <M-1> arranged in the first direction of the matrix. A non-driven linear sum signal (measured values without driving Dr0 / Dt0) based on the charges of a plurality of electrodes E on which a plurality of sense switch elements ST are formed is transmitted along the sense line SL <0> ... SL <M-1>. The non-driving read-out step of reading, the driving step of driving the plurality of electrodes E in parallel based on the code sequence M in order to charge the plurality of electrodes E, and the electric charge charged to the plurality of electrodes E by the driving step. The reading step of reading out the linear sum signal (normal drive measurement value Drp · Dtp) based on the sense line SL <0> ... SL <M-1>, and the above-mentioned from the linear sum signal (normal drive measurement value Drp · Dtp). It includes a detection step of subtracting a non-driven linear sum signal (measured value Dr0 · Dt0 without driving) to detect a capacitance distribution or a capacitance change distribution between the plurality of electrodes E and a detection target.

In the reference state, when the non-driven linear sum signal based on the charges of the plurality of electrodes E is read out along the sense lines SL <0> ... SL <M-1> without driving the plurality of electrodes E, (1) in FIG. As shown in Equation 17), undriven noise Nr0 is generated. Then, when the plurality of electrodes E are driven in parallel based on the code sequence M, normal drive noise Nrp is generated as shown in (Equation 16) of FIG. Next, the undriven measurement value Dr0 is subtracted from the normal drive measurement value Drp in the reference state as shown in (Equation 18).

After that, when the non-driven linear sum signal based on the charges of the plurality of electrodes E is read out along the sense lines SL <0> ... SL <M-1> in the measurement state without driving the plurality of electrodes E, As shown in (Equation 20) of FIG. 7, undriven noise Nt0 is generated. Then, when the plurality of electrodes E are driven in parallel based on the code sequence M, normal drive noise Ntp is generated as shown in (Equation 19) of FIG. Next, the undriven measurement value Dt0 is subtracted from the normal drive measurement value Dtp in the measurement state as shown in (Equation 21).

here,
ΔV∝ ((C1p-C1m) + (C2p-C2m)) Vd + (Cc1 + Cc2) Vd2,
Because it is
| (Cc1 + Cc2) Vd2 | >> | ((C1p-C1m) + (C2p-C2m)) Vd |,
When
Nrp ≒ Nr0, and Ntp ≒ Nt0,
It becomes.

Therefore, the approximate expression of (Equation 22) in FIG. 7 is established.

In this way, by subtracting the non-drive measurement value Dr0 from the normal drive measurement value Drp in the reference state, the normal drive noise Nrp in the reference state and the non-drive noise Nr0 are canceled out. Then, by subtracting the non-driven measurement value Dt0 from the normal drive measurement value Dtp in the measurement state, the normal drive noise Ntp in the measurement state and the non-drive noise Nt0 are canceled out.

[Embodiment 3]
Another embodiment of the present invention will be described below with reference to FIG. For convenience of explanation, the same reference numerals will be added to the members having the same functions as the members described in the above-described embodiment, and the description thereof will be omitted.

FIG. 8 is a diagram for explaining a capacity detection method by the touch panel system according to the third embodiment. The capacity estimation calculation according to the third embodiment is a reference in which the non-driven reading step reads a reference non-driven linear sum signal (measured value Dr0 without driving) in a reference state where there is no measurement target in the capacity estimation calculation according to the second embodiment. A non-driven readout step and a measurement non-driven readout step of reading a measurement non-driven linear sum signal (measured value Dt0 without drive) in a measurement state for detecting a measurement target are included, and the readout step is a reference linear sum in the reference state. The detection step includes a reference reading step of reading a signal (normal drive measurement value Drp) and a measurement reading step of reading a measurement linear sum signal (normal drive measurement value Dtp) in the measurement state, and the detection step is the reference linear sum signal (normal drive measurement value Dtp). The reference subtraction signal (normal drive measurement value Drp_cor) obtained by subtracting the reference non-drive linear sum signal (non-drive measurement value Dr0) from the normal drive measurement value Drp) and the measurement linear sum signal (normal drive measurement value Dtp) described above. A measurement subtraction signal (normal drive measurement value Dtp_cor) obtained by subtracting a measurement non-drive linear sum signal (non-drive measurement value Dt0) is generated, and the reference subtraction signal (normal drive) is generated from the measurement subtraction signal (normal drive measurement value Dtp_cor). The measured value Drp_cor) is subtracted to detect the capacitance distribution or the capacitance change distribution.

In the reference state, when the non-driven linear sum signal based on the charges of the plurality of electrodes E is read out along the sense lines SL <0> ... SL <M-1> without driving the plurality of electrodes E, (1) in FIG. As shown in Equation 17), the undriven measurement value Dr0 (Equation 23) corresponding to the undriven noise Nr0 is observed.

When a plurality of electrodes E are driven in parallel based on the code sequence M, as shown in (Equation 16) of FIG. 8, a normal drive measurement value Drp including a normal drive noise Nrp is observed. By injecting the canceling charge (-Dr0), the relationship of (Equation 24) can be obtained. As shown in (Equation 24), the normal drive measurement value Drp_cor in the reference state after the cancellation charge injection is obtained.

After that, when the non-driven linear sum signal based on the charges of the plurality of electrodes E is read out along the sense lines SL <0> ... SL <M-1> in the measurement state without driving the plurality of electrodes E, As shown in FIG. 8 (Equation 20), the undriven measurement value Dt0 (Equation 25) corresponding to the undriven noise Nt0 is observed.

When a plurality of electrodes E are driven in parallel based on the code sequence M, as shown in (Equation 19) of FIG. 8, a normal drive measurement value Dtp including a normal drive noise Ntp is observed. By injecting the canceling charge (−Dt0), the relationship of (Equation 26) can be obtained. As shown in (Equation 26), the normal drive measurement value Dtp_cor of the measurement state after the cancellation charge injection is obtained.

Then, the normal drive measurement value Drp_cor is subtracted from the normal drive measurement value Dtp_cor as shown in (Equation 27).

here,
ΔV∝ ((C1p-C1m) + (C2p-C2m)) Vd + (Cc1 + Cc2) Vd2,
Because it is
| (Cc1 + Cc2) Vd2 | >> | ((C1p-C1m) + (C2p-C2m)) Vd |,
When
Nrp ≒ Nr0, and Ntp ≒ Nt0,
It becomes.

Therefore, the approximate expression of (Equation 28) in FIG. 8 is established.

In this way, by subtracting the normal drive measurement value Drp_cor in the reference state from the normal drive measurement value Dtp_cor in the measurement state, the normal drive noise Ntp in the measurement state and the non-drive noise Nt0 in the measurement state cancel each other out, and the normal drive noise in the reference state. Nrp and undriven noise Nr0 cancel each other out.

[Embodiment 4]
Further, another embodiment of the present invention will be described below with reference to FIGS. 9 to 14. For convenience of explanation, the same reference numerals will be added to the members having the same functions as the members described in the above-described embodiment, and the description thereof will be omitted.

(Reference electrode)
FIG. 9 is a circuit diagram showing the configuration of the touch panel system 1A according to the fourth embodiment. FIG. 10 is a diagram for explaining a capacity detection method by the touch panel system according to the fourth embodiment. The touch panel system 1A includes a touch panel 2A and a touch panel controller 3. The touch panel 2A has K drive lines DL <0> to DL <K-1> that intersect each other, M sense lines SL <0> to SL <M-1>, and K drive lines. (K × M) detection electrodes arranged in a matrix corresponding to the intersection of DL <0> to DL <K-1> and M sense lines SL <0> to SL <M-1>. E and a reference electrode ES are provided.

In the example shown in FIG. 9, the reference electrode ES is arranged in the first row, and the detection electrode E is arranged in the second to K rows. Each reference electrode ES is covered with a shield layer 13 (AC grounded electrode) having a potential that is AC grounded so as not to have an AC component. Therefore, the reference electrode ES is not affected by the measurement target.

The capacity estimation calculation according to the fourth embodiment is performed by a plurality of detection electrodes E arranged in a matrix, between a plurality of sense lines SL <0> ... SL <M + 1> arranged in the first direction of the matrix. A reference drive step of driving the plurality of electrodes E in parallel based on the code sequence M in a reference state where there is no measurement target in order to charge the plurality of electrodes E on which the plurality of sense switch elements ST are formed, and the reference drive step. A reference reading process for reading out a reference linear sum signal (normal drive measurement value Drp) based on the charges charged to the plurality of electrodes E along the sense line SL <0> ... SL <M + 1>, and a measurement for detecting the measurement target. A measurement drive step in which the plurality of electrodes E are driven in parallel based on the code sequence M in order to charge the plurality of electrodes E in a state, and a measurement based on the electric charge charged in the plurality of electrodes E by the measurement drive step. The plurality of electrodes E include a measurement reading step of reading a linear sum signal (normal drive measurement value Dtp) along the sense line SL <0> ... SL <M + 1> so as not to be affected by the measurement target. A part of the above-mentioned measurement alignment is arranged as a reference electrode ES surrounded by an AC ground electrode (shield layer 13) having a potential that is AC grounded (AC grounded) so as not to have an AC component. The capacitance between the plurality of electrodes E and the detection target based on the subtraction result obtained by subtracting the reference linear sum signal (normal drive measurement value Drp) from the sum signal (normal drive measurement value Dtp) and the code sequence M. A decoding step of decoding the distribution or the capacitance change distribution, and a correction step of correcting the decoded capacitance distribution or the capacitance change distribution based on the decoding result of the portion where the reference electrode ES is arranged among the plurality of electrodes E. Is further included.

In the fourth embodiment, a part of the plurality of detection electrodes E is the reference electrode ES. The reference electrode ES is surrounded by a shield layer 13 (AC ground electrode) that is always AC grounded and shielded by the ground so as not to be affected by the external environment. Then, the capacitance distribution or the capacitance change distribution is corrected so that the detection result of the capacitance value based on the linear sum signal from the reference electrode ES becomes zero.

When a plurality of electrodes E are driven in parallel based on the code sequence M in the reference state, a normal drive measurement value Drp including the normal drive noise Nrp is observed as shown in (Equation 16) of FIG. Then, when a plurality of electrodes E are driven in parallel based on the code sequence M in the measurement state, as shown in FIG. 10 (Equation 19), a normal drive measurement value Dtp including the normal drive noise Ntp is observed.

Then, as shown in (Equation 29) of FIG. 10, the normal drive measurement value Drp in the reference state is subtracted from the normal drive measurement value Dtp in the measurement state.

here,
ΔV∝ ((C1p-C1m) + (C2p-C2m)) Vd + (Cc1 + Cc2) Vd2,
Because it is
| (Cc1 + Cc2) Vd2 | >> | ((C1p-C1m) + (C2p-C2m)) Vd |,
When
Nrp ≒ Nr * Ones, and Ntp ≒ Nt * Ones,
It becomes.

Here, Nr and Nt are scalar quantities, and Ones is a matrix in which all the elements are "1".

Then, (Equation 30) of FIG. 10 is derived. This (Equation 30) means that an error of (Nt-Nr) * Ones * M- ¹ is mixed in the calculation result of (Dtp-Drp) * M- ^1.

If the touch panel 2A is provided with a reference electrode ES surrounded by a shield layer 13 (AC ground electrode) that is AC grounded and shielded to the ground, the location where the reference electrode ES is arranged is (Ct-Cr). ) = 0. ^{Therefore, the influence of ((Nt-Nr) * Ones * M-1} ) can be estimated from the decoding result of the linear sum signal from the reference electrode ES. If the effect of (Nt-Nr) * Ones * M ^{-1 on} the reference electrode ES can be estimated, then (Ones * M ^-1 ) is known, and the entire region of the touch panel 2A on which the detection electrode E is arranged ( The effect (Dcal) of (Nt-Nr) * Ones * M- ^{1) can be estimated.} Then, as shown in (Equation 31), switching noise can be reduced by subtracting Dcal from ^{((Dtp-Drp) * M -1).}

(Influence of (Ones * M ^-1))
A method of selecting a drive / decode matrix in which the influence of the Ones matrix decoding operation result (Ones * M ^{-1) is small will be described.} As described above in (Equation 30), the switching noise represented by ((Nt-Nr) * Ones * M- ^{1) on the right side of the following (Equation 32) is mixed in the decoding result of the linear sum signal.}

Here, (Ones * M ^-1 ) will be examined in detail.

11 to 14 are diagrams showing an example of a drive / decoding operation using the M matrix according to the fourth embodiment. When the M (Maximum transpose) matrix shown in FIG. 11 is used as the code sequence for driving the detection electrode E, M ^-1 replaces the element "-1" contained in the M matrix with "0". It will be transposed. To make M ^{-1 an} inverse matrix, it is necessary to multiply by a scalar quantity of (2 / (code length + 1)), but it is ignored here.

When an inverse matrix is used as the decoding matrix, in the examples shown in FIGS. 11 and 12, M * M ^-1 becomes 8 * E (E is an identity matrix), and Ones * M ^-1 becomes 8 * Ones.

When the transposed matrix (Mt) of the M matrix is used as the decoding matrix instead of the inverse matrix, in the examples shown in FIGS. 13 and 14, M * Mt Dij (i = j) is 15, Dij (i ≠ j). Is -1, and Ones * Mt is Ones.

In the example shown in FIG. 13, since Dij (i ≠ j) is -1, the influence (error) of other elements is included, but this influence (error) is small in a system that can be approximated to ΣDij (i ≠ j) ≈ 0. ..

Since the influence of Ones * Mt related to the transposed matrix (Mt) is smaller than the influence of Ones * M- ^{1 and} the influence of Ones * Mt, if the influence of this noise is to be reduced, the transposed matrix (Mt) is added to the transposed matrix (Mt). Should be adopted.

A 15-by-15 M-matrix (M) and a matrix with all elements 1 (Ones), a 15-by-15 M-matrix (M) pseudo-transposed matrix (M- ¹ ) and a 15-by-15 M-matrix. The matrix calculation results when decoded by the transposed matrix (Mt) are shown in FIGS. 11 to 14. The pseudo-inverse matrix means a matrix in which the driving matrix is transposed and -1 is changed to 0.

The noise decoding result when the same switching noise (switching noise) is input every time regardless of the drive code corresponds to the decoding result of the Ones matrix.

As shown by the calculation results shown in FIGS. 11 and 12, the signal component becomes 8 times and the noise component becomes 8 times.

When a transposed matrix (Mt) is used as the decoding matrix, the signal component is 15 times (the number of wraparounds from other lines is -1 times 14), and the noise component is 1 time.

[Embodiment 5]
Still other embodiments of the present invention will be described below with reference to FIGS. 15-18. For convenience of explanation, the same reference numerals will be added to the members having the same functions as the members described in the above-described embodiment, and the description thereof will be omitted.

As described in the fourth embodiment, the decoding result of the linear sum signal is mixed with the switching noise represented by ^{((Nt-Nr) * Ones * M-1) on the right side of the following (Equation 32).}

15 to 18 are diagrams showing an example of a drive / decoding operation using the Hadamard matrix according to the fifth embodiment. When the H (Hadamard) matrix shown in FIG. 15 is used as the code sequence for driving the detection electrode E, H ^-1 becomes H itself (transposes H). In ^{order to make H -1 an} inverse matrix, it is necessary to multiply by the scalar amount of 1 / code length, but it is ignored here.

When an inverse matrix is used as the decoding matrix, in the examples shown in FIGS. 15 and 16, H * H is 16 * E (E is an identity matrix), only the first column of Ones * H is 16, and the others are 0. .. The matrix shown in FIG. 16 may be used in a simtem where the results in the first column can be ignored.

16 rows x 16 columns H matrix (H) and all elements 1 matrix (Ones), 16 rows x 16 columns H matrix pseudo-inverse matrix (H = H ^-1 ), and the first row of the H matrix The matrix calculation results in the case of decoding with (H0) (* 1) in which is replaced with 0 are shown in FIGS. 15 to 18. The noise decoding result when the same switching noise (switching noise) is input every time regardless of the drive code corresponds to the decoding result of the Ones matrix.

When the H0 matrix in which the first row of the inverse matrix is replaced with 0 is used as the decoding matrix, in the examples shown in FIGS. 17 and 18, the Dij (i = j) of H * H0 is 15, and the Dij (i ≠ j). Is -1, and Ones * Mt is Ones.

In the example shown in FIG. 17, since Dij (i ≠ j) is -1, the influence (error) of other elements is included, but in a system where ΣDij (i ≠ j) ≈ 0, this component becomes small.

In the examples shown in FIGS. 15 and 16, the decoding operation is performed including the data that drives all the drive lines with 1, but this condition is that the amplifier output from the differential amplifier 7 tends to be saturated. As the amount of input common shift increases, the effect of error increases, so it may be desirable to avoid it.

In such a case, the H0 matrix in which the first row of the inverse matrix is replaced with 0 may be used as the decoding matrix (the drive of all = 1 is unnecessary and may be deleted).

19 (a) and 19 (b) are diagrams showing an example of the capacity detection result according to the fourth embodiment. 19 (a) and 19 (b) use the M127 matrix for the code sequence for driving the detection electrode E, and use the pseudo-inverse matrix of the M127 matrix for the decoding code of (a). The transposed matrix of the M127 matrix is used as the decoding code. The pseudo-inverse matrix means a matrix in which the driving matrix is transposed and -1 is changed to 0.

FIG. 19B is an example of the detection result of the embodiment in which the transposed matrix of the M127 matrix is used as the decoding code. However, the expected capacitance distribution may be observed by decoding with the transposed matrix of the M127 matrix. It is shown that.

[Embodiment 6]
Another embodiment of the present invention will be described below with reference to FIG. For convenience of explanation, the same reference numerals will be added to the members having the same functions as the members described in the above-described embodiment, and the description thereof will be omitted.

FIG. 20 is a circuit diagram showing the configuration of the touch panel system 1B according to the sixth embodiment. The capacity estimation calculation described in the first to fifth embodiments can also be applied to the touch panel system 1B in which the sense lines shown in FIG. 20 are multiplexed.

The multiplication unit 10 includes a code multiplication unit 11 and an amplification unit 12. The code multiplication unit 11 includes a switch element SW for each of the sense lines SL <0> to SL <M-1>. The amplification unit 12 includes an operational amplifier 121. An integral capacitance Cint is provided between the non-inverting input of the operational amplifier 121 and one of the outputs. An integral capacitance Cint is also provided between the inverting input of the operational amplifier 121 and the other output. The operational amplifier 121 may include a switch (not shown) for resetting the state of the operational amplifier 121 by short-circuiting one terminal of the integrated capacitance Cint and the other terminal.

The code multiplication unit 11 includes a switch element SW provided for each sense line SL <0> to SL <M-1> according to the _{detection codes E 0 to} E _M-1 , which are values of “+1” or “-1”. Switch. When the detection code Ei is "+1", the code multiplication unit 11 connects the sense line SLi to the non-inverting input of the operational amplifier 121 of the amplification unit 12. When the detection code Ei is "-1", the code multiplication unit 11 connects the sense line SLi to the inverting input of the operational amplifier 121. Here, i is any value from 0 to M-1. That is, in the touch panel system 1A, the plurality of sense lines are multiplexed so as to correspond to one operational amplifier. In one multiplexing, a detection code sequence consisting of a plurality of detection codes multiplied by a plurality of sense lines is used.

The amplification unit 12 amplifies the linear sum signal based on the charge of each detection electrode E read along the sense line connected to the non-inverting input and the inverting input of the operational amplifier 121. Next, the detection circuit 6 detects the capacitance or the capacitance change between each detection electrode E of the touch panel 2 and the detection target based on the signal output from the amplification unit 12. After that, the detection circuit 6 detects the position of the detection target on the touch panel 2 based on the detected capacitance or the capacitance change.

[Embodiment 7]
Another embodiment of the present invention will be described below with reference to FIG. For convenience of explanation, the same reference numerals will be added to the members having the same functions as the members described in the above-described embodiment, and the description thereof will be omitted.

FIG. 21 is a circuit diagram showing the configuration of the touch panel system 1C according to the seventh embodiment. The capacitance estimation calculation described in the first to fifth embodiments can also be applied to the touch panel system 1C related to the parallel drive of the one-transistor system shown in FIG.

The touch panel system 1C configured as shown in FIG. 21 operates as follows.

First, the switch element control circuit 8 is a code sequence of K rows and N columns from (K × M) drive sense switch elements DST via K control lines DSS <0> to DSS <K-1>. The drive sense switch element DST selected based on the element "1" is turned on. At this time, the unselected drive sense switch element DST is in the off state. Further, the changeover switch SW is switched so as to connect the drive circuit 4 and the M drive sense lines DSL <0> to DSL <M-1>. Then, the drive circuit 4 drives M drive sense lines DSL <0> to DSL <M-1>, and charges each detection electrode E to + V (for example, power supply voltage) through the selected drive sense switch element DST. (First drive step).

Next, the switch element control circuit 8 is a code sequence of K rows and N columns from (K × M) drive sense switch elements DST via K control lines DSS <0> to DSS <K-1>. The drive sense switch element DST selected based on the element "-1" of is turned on. At this time, the unselected drive sense switch element DST is in the off state. Here, the changeover switch SW is switched so as to connect the drive circuit 4 and the M drive sense lines DSL <0> to DSL <M-1>. Then, the drive circuit 4 drives M drive sense lines DSL <0> to DSL <M-1>, and sets each detection electrode E to −V (for example, ground voltage) through the selected drive sense switch element DST. Charge.

Next, the switch element control circuit 8 turns off (K × M) drive sense switch elements DST via K control lines DSS <0> to DSS <K-1>, and sets each detection electrode E. Make it floating. Further, the changeover switch SW is switched so as to connect the read circuit 5 and the M drive sense lines DSL <0> to DSL <M-1>. After that, the switch element control circuit 8 turns on (K × M) drive sense switch elements DST via K control lines DSS <0> to DSS <K-1>.

Then, each read circuit 5 amplifies the difference of the linear sum signal based on the charge of each detection electrode E read along the adjacent drive sense line via the turned-on drive sense switch element DST. Next, the detection circuit 6 increases the capacitance between each detection electrode E of the touch panel 2 and the detection target based on the product-sum calculation of the difference between the linear sum signals output from each readout circuit 5 and the code sequence. Detect capacity changes. After that, the detection circuit 6 detects the position of the detection target on the touch panel 2 based on the detected capacitance or the capacitance change.

[Summary]
The capacitance detection method according to the first aspect of the present invention is a plurality of electrodes E arranged in a matrix, and a plurality of first signal lines (sense lines SL <0> ... SL < A plurality of electrodes E in which a plurality of first switch elements (sense switch element ST, drive sense switch element DST) are formed between M-1> and drive sense line DSL <0> to DSL <M-1>). The first signal line (sense line) is a drive step in which the plurality of electrodes E are driven in parallel based on a code sequence to charge the plurality of electrodes E, and a linear sum signal based on the charges charged in the plurality of electrodes E by the drive step. SL <0> ... SL <M-1>, read-out step along the drive sense line DSL <0> to DSL <M-1>), and the plurality of electrodes E to charge the plurality of electrodes E. The first signal line (sense line SL <0> ... SL) is a reverse linear sum signal based on the charges charged in the plurality of electrodes E by the reverse drive step and the reverse drive step in which the two electrodes are driven in parallel based on the reverse code sequence. <M-1>, a reverse reading step of reading along the drive sense line DSL <0> to DSL <M-1>), and subtracting the inverted linear sum signal from the linear sum signal to form the plurality of electrodes E. It includes a detection step of detecting a capacity distribution or a capacity change distribution with a detection target.

According to the above configuration, the inverted linear sum signal is subtracted from the linear sum signal. Therefore, it is possible to reduce the influence of switching noise caused by the on / off operation of the switch provided between the sense line and each detection electrode on the detection result such as capacitance.

The capacitance detection method according to the second aspect of the present invention is a plurality of electrodes E arranged in a matrix, and a plurality of first signal lines (sense lines SL <0> ... SL < A plurality of electrodes E in which a plurality of first switch elements (sense switch element ST, drive sense switch element DST) are formed between M-1> and the drive sense line DSL <0> to DSL <M-1>). The non-driving linear sum signal based on the electric charge of is read out along the first signal line (sense line SL <0> ... SL <M-1>, driving sense line DSL <0> to DSL <M-1>). A drive reading step, a drive step of driving the plurality of electrodes E in parallel based on a code sequence to charge the plurality of electrodes E, and a linear sum based on the charges charged to the plurality of electrodes E by the drive step. From the reading step of reading the signal along the first signal line (sense line SL <0> ... SL <M-1>, drive sense line DSL <0> to DSL <M-1>), and the linear sum signal. It includes a detection step of subtracting the non-driven linear sum signal to detect a capacitance distribution or a capacitance change distribution between the plurality of electrodes and a detection target.

According to the above configuration, the non-driven linear sum signal is subtracted from the linear sum signal. Therefore, it is possible to reduce the influence of switching noise caused by the on / off operation of the switch provided between the sense line and each detection electrode on the detection result such as capacitance.

In the capacitance detection method according to the third aspect of the present invention, in the second aspect, the non-driven readout step reads a reference non-driven linear sum signal in a reference state where there is no measurement target, and detects a measurement target. The measurement non-driven sum signal is read out in the measurement state, and the read step includes the reference read step of reading the reference linear sum signal in the reference state and the measurement linear sum signal in the measurement state. The detection step includes a reference subtraction signal obtained by subtracting the reference non-drive linear sum signal from the reference linear sum signal, and a reference subtraction signal obtained by subtracting the measurement non-drive linear sum signal from the measurement linear sum signal. The measurement subtraction signal may be generated, and the reference subtraction signal may be subtracted from the measurement / subtraction signal to detect the capacitance distribution or the capacitance change distribution.

According to the above configuration, a reference subtraction signal obtained by subtracting the reference non-drive linear sum signal from the reference linear sum signal and a measurement subtraction signal obtained by subtracting the measurement non-drive linear sum signal from the measurement linear sum signal are generated. Will be done. Then, the reference subtraction signal is subtracted from the measurement subtraction signal. Therefore, it is possible to reduce the influence of switching noise caused by the on / off operation of the switch provided between the sense line and each detection electrode on the detection result such as capacitance.

The capacitance detection method according to the fourth aspect of the present invention is a plurality of electrodes E arranged in a matrix, and a plurality of first signal lines (sense lines SL <0> ... SL < A plurality of electrodes E in which a plurality of first switch elements (sense switch element ST, drive sense switch element DST) are formed between M-1> and drive sense line DSL <0> to DSL <M-1>). A reference drive step in which the plurality of electrodes E are driven in parallel based on a code sequence in a reference state where there is no measurement target, and a reference linear sum based on the charges charged in the plurality of electrodes E by the reference drive step. A reference reading process for reading a signal along the first signal line (sense line SL <0> ... SL <M-1>, drive sense line DSL <0> to DSL <M-1>), and detection of a measurement target. Based on a measurement drive step in which the plurality of electrodes E are driven in parallel based on the code sequence in order to charge the plurality of electrodes E in the measurement state, and a charge charged in the plurality of electrodes E by the measurement drive step. The measurement reading step of reading the measurement linear sum signal along the first signal line (sense line SL <0> ... SL <M-1>, drive sense line DSL <0> to DSL <M-1>) is included. However, a part of the plurality of electrodes E is surrounded and shielded by an AC ground electrode having a potential that is AC grounded so as not to have an AC component so as not to be affected by the measurement target. The capacitance distribution or capacitance change distribution between the plurality of electrodes E and the detection target is decoded based on the subtraction result obtained by subtracting the reference linear sum signal from the measured linear sum signal and the code sequence arranged as electrodes. The decoding step is further included, and a correction step of correcting the decoded capacitance distribution or capacitance change distribution based on the decoding result of the portion of the plurality of electrodes E where the reference electrode is arranged.

According to the above configuration, the decoded capacitance distribution or capacitance change distribution is corrected based on the decoding result of the portion where the reference electrode is arranged among the plurality of electrodes. Therefore, it is possible to reduce the influence of switching noise caused by the on / off operation of the switch provided between the sense line and each detection electrode on the detection result such as capacitance.

In the capacity detection method according to the fifth aspect of the present invention, in the fourth aspect, the code sequence is an M (Maximum length sequence) matrix, and the decoding step is based on the transposed matrix of the M matrix and the subtraction result. The capacitance distribution or the capacitance change distribution may be decoded.

According to the above configuration, the influence of noise related ^{to Ones * M-1 can be reduced.}

In the capacitance detection method according to the sixth aspect of the present invention, in the fourth aspect, the code sequence is a Hadamard matrix, and the decoding step replaces the first row of the inverse matrix of the Hadamard matrix with zero. The capacitance distribution or the capacitance change distribution may be decoded based on the matrix and the subtraction result.

According to the above configuration, saturation of the output of the differential amplifier can be prevented.

In the capacitance detection method according to the seventh aspect of the present invention, in the fourth aspect, the code sequence is a Hadamard matrix, and the decoding step decodes the first column of the decoded capacitance distribution or the capacitance change distribution. The range excluding the result may be adopted as the capacity distribution or the capacity change distribution.

According to the above configuration, noise due to saturation of the output of the differential amplifier can be eliminated.

In the capacity detection method according to the eighth aspect of the present invention, in the first or second aspect, the plurality of second signal lines intersecting the first direction and arranged in the second direction and the plurality of electrodes are located between the plurality of second signal lines. The switch element may be formed, and the driving step may drive the plurality of electrodes in parallel along the second signal line.

In the capacity detection method according to the ninth aspect of the present invention, in the fourth aspect, a plurality of second switch elements are provided between the plurality of second signal lines arranged in the second direction intersecting the first direction and the plurality of electrodes. Is formed, and the reference driving step and the measurement driving step may drive the plurality of electrodes in parallel along the second signal line.

According to the above configuration, in a touch panel system of a two-transistor system or a sense line multiplexing system, switching noise caused by the on / off operation of a switch provided between the sense line and each detection electrode is detected as a capacitance or the like. The impact on the results can be reduced.

In the capacitance detection method according to the tenth aspect of the present invention, in the first or second aspect, the driving step may drive the plurality of electrodes in parallel along the first signal line.

In the capacitance detection method according to the eleventh aspect of the present invention, in the fourth aspect, the reference driving step and the measurement driving step may drive the plurality of electrodes in parallel along the first signal line.

According to the above configuration, in a one-transistor type touch panel system, the influence of switching noise caused by the on / off operation of the switch provided between the sense line and each detection electrode on the detection result such as capacitance is reduced. can do.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

1 Touch panel system 2 Touch panel 3 Touch panel controller 4 Drive circuit 5 Read circuit 6 Detection circuit 7 Differential amplifier 8 Switch element control circuit 10 Multiplying unit 11 Code multiplying unit 12 Amplifying unit 13 Shield layer (AC ground electrode)
E Detection electrode (electrode)
ES reference electrode SL <0> ... SL <M-1> Sense line (first signal line)
ST sense switch element (first switch element)
DL <0> ... DL <K-1> Drive line (second signal line)
DSL <0> to DSL <M-1> Drive sense line (first signal line)
SS <0> to SS <K-1> Sense control line DS <0> to DS <K-1> Drive control line DSS <0> to DSS <K-1> Control line DT Drive switch element (second switch element) )
DST drive sense switch element (first switch element)
Cint integrated capacitance C1p, C2p Capacitance formed by the detection electrode E driven by the code (+1) C1m, C2m Capacitance formed by the detection electrode E driven by the code (-1) Cp1, Cp2 parasitic Capacitance Cc1, Cc2 Noise forming a noise charge mixing path Capacitance Vc Common voltage Vd Drive voltage Vd2 Switching noise voltage ΔV Input common shift voltage Vout Output voltage M Code series

Claims (10)

A plurality of electrodes arranged in a matrix, and a plurality of first switch elements are formed between the plurality of first signal lines arranged in the first direction of the matrix. Non-driving based on the charge of the plurality of electrodes. A non-driven read-out step of reading out a linear sum signal along the first signal line,
A driving step of driving the plurality of electrodes in parallel based on a code sequence to charge the plurality of electrodes.
A reading step of reading out a linear sum signal based on the charges charged to the plurality of electrodes by the driving step along the first signal line, and
A capacitance detection method comprising a detection step of subtracting the non-driven linear sum signal from the linear sum signal to detect a capacitance distribution or a capacitance change distribution between the plurality of electrodes and a detection target. The non-driven readout step is a reference non-driven readout step of reading a reference non-driven linear sum signal in a reference state where there is no measurement target, and a measurement non-driven readout step of reading a measurement non-driven linear sum signal in a measurement state of detecting a measurement target. Including and
The reading step includes a reference reading step of reading a reference linear sum signal in the reference state and a measurement reading step of reading a measurement linear sum signal in the measurement state.
The detection step generates a reference subtraction signal obtained by subtracting the reference non-drive linear sum signal from the reference linear sum signal and a measurement subtraction signal obtained by subtracting the measurement non-drive linear sum signal from the measurement linear sum signal. The capacitance detection method according to claim 1 , wherein the reference subtraction signal is subtracted from the measurement subtraction signal to detect the capacitance distribution or the capacitance change distribution. A plurality of electrodes arranged in a matrix, for charging a plurality of electrodes in which a plurality of first switch elements are formed between a plurality of first signal lines arranged in a first direction of the matrix. A reference drive process in which multiple electrodes are driven in parallel based on a code sequence in a reference state where there is no measurement target,
A reference reading step of reading out a reference linear sum signal based on the charges charged to a plurality of electrodes by the reference driving step along the first signal line, and
A measurement driving step of driving the plurality of electrodes in parallel based on the code sequence in order to charge the plurality of electrodes in a measurement state for detecting a measurement target.
It includes a measurement reading step of reading out a measurement linear sum signal based on the charges charged to a plurality of electrodes by the measurement driving step along the first signal line.
A part of the plurality of electrodes is arranged as a reference electrode surrounded and shielded by an AC grounded electrode having an AC grounded potential so as not to have an AC component so as not to be affected by the measurement target. Being done
A decoding step of decoding the capacitance distribution or the capacitance change distribution between the plurality of electrodes and the detection target based on the subtraction result obtained by subtracting the reference linear sum signal from the measured linear sum signal and the code sequence.
A capacitance detection method further comprising a correction step of correcting the decoded capacitance distribution or capacitance change distribution based on the decoding result of a portion of the plurality of electrodes where a reference electrode is arranged. The code sequence is an M (Maximum length sequence) matrix.
The capacity detection method according to claim 3 , wherein the decoding step decodes the capacity distribution or the capacity change distribution based on the transposed matrix of the M matrix and the subtraction result. The code sequence is a Hadamard matrix.
The capacity detection method according to claim 3 , wherein the decoding step decodes the capacity distribution or the capacity change distribution based on the matrix in which the first row of the inverse matrix of the Hadamard matrix is replaced with zero and the subtraction result. The code sequence is a Hadamard matrix.
The capacity detection method according to claim 3 , wherein the decoding step adopts a range excluding the decoding result of the first column of the decoded capacity distribution or capacity change distribution as the capacity distribution or capacity change distribution. A plurality of second switch elements are formed between the plurality of second signal lines intersecting the first direction and arranged in the second direction and the plurality of electrodes.
It said driving step, the capacitance detection method according to claim 1 in parallel driving a plurality of electrodes along the second signal line. A plurality of second switch elements are formed between the plurality of second signal lines intersecting the first direction and arranged in the second direction and the plurality of electrodes.
The capacitance detection method according to claim 3 , wherein the reference drive step and the measurement drive step drive the plurality of electrodes in parallel along the second signal line. It said driving step, the capacitance detection method according to claim 1 in parallel driving a plurality of electrodes along the first signal line. The capacitance detection method according to claim 3 , wherein the reference drive step and the measurement drive step drive the plurality of electrodes in parallel along the first signal line.

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