WO2014208174A1 - Touch panel controller, touch panel system, and electronic device - Google Patents

Abstract

This touch panel controller (110) is provided with a drive unit (111) which, on the basis of a code series of series length N, drives M (M ≧ 2) drive lines (DL1-DLM) and outputs N linear sum signals from one sense line (SL1-SLP), signal processing units (114a, 114b) which output N output signals by sequentially updating K (0 < K < N) linear sum signals, and inner product calculation units (115a, 115b) which calculate the inner products of the abovementioned output signals and the abovementioned code series and calculate an estimated capacitance value.

Description

Touch panel controller, touch panel system, and electronic device

The present invention relates to a touch panel controller, an integrated circuit including the touch panel controller, a touch panel system, and an electronic device.

Touch panel systems are widely used in various electronic devices such as PCs (Personal Computers), mobile phones, and tablets. In the touch panel system, an input operation to the touch panel is performed when the user brings his / her finger or touch pen into contact with the touch panel.

In the capacitive touch panel system, a change in electrostatic capacitance in the touch panel, which is caused when a user's finger or touch pen touches the touch panel, is detected. Then, the position where the capacitance change occurs on the touch panel is recognized as the input position for the touch panel.

In Patent Document 1, as a device for detecting capacitance values distributed in a matrix, (P × M) static electricity formed at each intersection of M drive lines and P sense lines. A touch panel system including a touch panel controller that detects (estimates) a distribution of capacitance is disclosed.

Hereinafter, the touch panel system disclosed in Patent Document 1 will be described with reference to FIGS. 6 and 7.

(Configuration of touch panel system 1000 disclosed in Patent Document 1)
FIG. 6 is a diagram illustrating a configuration of a touch panel 1000 which is an example of a configuration of the touch panel system disclosed in Patent Document 1. As illustrated in FIG. The touch panel system 1000 includes a touch panel controller 1010 and a touch panel 1020.

(Touch panel 1020)
The touch panel 1020 includes M (M is an integer of 2 or more) drive lines DL1 to DLM arranged in parallel with each other along the vertical direction, and P (P is a parallel display) arranged in parallel with each other along the horizontal direction. (Integer greater than or equal to 1) sense lines SL1 to SLP.

In the touch panel 1020, (P × M) capacitances C11 to CPM are formed at the intersections of the drive lines DL1 to DLM and the sense lines SL1 to SLP. Here, the capacitance CPM represents the capacitance formed at the intersection of the sense line SLP and the drive line DLM.

FIG. 6 illustrates the case of M = P = 4. That is, on the touch panel 1020, respective capacitances C11 to C44 are formed at intersections of the drive lines DL1 to DL4 and the sense lines SL1 to SL4.

(Touch panel controller 1010)
The touch panel controller 1010 includes a drive unit 1011. The touch panel controller 1010 includes differential amplifiers 1012a and 1012b as two differential amplifiers.

(Driver 1011)
The drive unit 1011 drives the drive lines DL1 to DL4 in parallel based on a code sequence having a sequence length N (N is an integer). FIG. 7 shows an M-sequence code MC1 for generating a code sequence used for driving the drive lines DL1 to DL4 by the drive unit 1011.

The M-sequence code MC1 is an M-sequence code having a sequence length of 31 (that is, N = 31). Here, the M-sequence code MC1 is represented as a 31 × 31 square matrix in which the value of each component of the matrix is either “1” or “−1”.

Each row (1st to 31st rows) in the M-sequence code MC1 corresponds to each of 31 signals 1st Vector to 31th Vector. Each column (first column to 31st column) in the M-sequence code MC1 corresponds to each of 31 signals Drive1 to Drive31.

A signal 1st Vector to 31th Vector included in the M-sequence code MC1 is a signal that defines a value of a voltage to be applied to each drive line in the i-th drive drive (1 ≦ i ≦ 31). The drive unit 1011 drives all drive lines (up to 31 drive lines) 31 times based on the signal 1st Vector to 31th Vector.

The driving unit 1011 applies the voltage Vdrive to the Xth drive line DLX when the component of the Xth (1 ≦ X ≦ M) signal DriveX is “1” in the i-th driveline drive. In addition, when the component of the Xth signal DriveX is “−1”, the driving unit 1011 applies a voltage (−Vdrive) to the Xth drive line DLX.

Therefore, the drive unit 1011 drives each of the 31 drive lines based on the signals Drive1 to Drive31. Signals Drive1 to Drive31 are code sequences used for driving the drive lines DL1 to DL31, and are hereinafter referred to as code sequences Drive1 to Drive31.

Here, a case is considered in which the drive unit 1011 drives the drive lines DL1 to DL4 based on four code sequences Drive1 to Drive4 among the 31 code sequences Drive1 to Drive31. Here, the sequence length N of the code sequences Drive1 to Drive31 is N = 31, and the number M of drive lines is M = 4.

The voltage Vdrive may be a power supply voltage applied to the touch panel system 1000, for example. Further, as the voltage Vdrive, a voltage other than the power supply voltage such as a reference voltage applied to the touch panel system 1000 may be used.

( Differential amplifiers 1012a and 1012b)
The differential amplifiers 1012a and 1012b are two-input two-output amplifiers that amplify the difference between the two input signals and output them as output signals.

The differential amplifiers 1012a and 1012b are each connected to two integration capacitors Cint. That is, one of the integration capacitors Cint is connected between one input terminal and one output terminal of the differential amplifier 1012a or 1012b. The other one of the integration capacitors Cint is connected between the other input terminal and the other output terminal of the differential amplifier 1012a or 1012b.

The differential amplifier 1012a is arranged so that signals acquired from the sense lines SL1 and SL2 are input thereto.

Accordingly, the differential amplifier 1012a receives an input signal from the sense line SL1 (linear sum signal relating to the capacitance formed at the intersection of the sense line SL1 and the drive lines DL1 to DL4) and an input signal from the sense line SL2 ( The difference between the sense line SL2 and the linear sum signal relating to the capacitance formed at the intersections of the drive lines DL1 to DL4 is amplified and output as an output signal. The output signal output from the differential amplifier 1012a is also a linear sum signal related to capacitance.

Similarly, the differential amplifier 1012b is arranged such that signals acquired from the sense lines SL3 and SL4 are input thereto.

Accordingly, the differential amplifier 1012b includes an input signal from the sense line SL3 (a linear sum signal related to the capacitance formed at the intersection of the sense line SL3 and the drive lines DL1 to DL4) and the sense line SL4 (the sense line SL4 and the sense line SL4). The difference from the input signal from the linear sum signal regarding the capacitance formed at the intersections with the drive lines DL1 to DL4 is amplified and output as an output signal. The output signal output from the differential amplifier 1012b is also a linear sum signal related to capacitance.

(Estimation of capacitance in touch panel system 1000)
Next, estimation of capacitance in the touch panel system 1000 disclosed in Patent Document 1 will be described.

Based on the signal 1st Vector of the code sequence MC1, the drive unit 1011 drives the first drive lines DL1 to DL4 with the code sequence of (Drive1, Drive2, Drive3, Drive4) = (1, -1,1,1). I do.

Accordingly, in the first drive of the drive lines DL1 to DL4, the drive unit 1011 applies (i) the voltage Vdrive to the drive lines DL1, DL3, and DL4, and (ii) applies the voltage (−Vdrive) to the drive line DL2. ) Is applied.

Here, attention is paid to the output of the differential amplifier 1012b to which the input signals from the sense lines SL3 and SL4 are given. Now, the linear sum signal Y1 as the output of the differential amplifier 1012b in the first drive of the live lines DL1 to DL4 is expressed by the following equation (1).

Here, the respective components of the code sequences Drive1 to Drive4 in the drive of the drive lines DL1 to DL4 for the i (1 ≦ i ≦ 31) times are represented by code sequences Di, 1, Di, 2, Di, 3, and Di, This is expressed as 4. For example, at i = 1, Di, 1 = 1, Di, 2 = −1, Di, 3 = 1, Di, 4 = 1.

At this time, the linear sum signal Yi as the output of the differential amplifier 1012b in driving the i-th live lines DL1 to DL4 is expressed by the following equation (2).

In the touch panel system 1000, (i) a linear sum signal output from the differential amplifiers 1012a and 1012b, and (ii) any one of the code sequences Di, 1, Di, 2, Di, 3 or Di, 4 The capacitance formed on the touch panel 1020 is estimated by the inner product calculation. Here, a case where the value of the difference in capacitance (C31-C41) is estimated using the linear sum signal Yi output from the differential amplifier 1012b will be described.

The driving unit 1011 drives the drive lines DL1 to DL4 31 times based on the signal 1st Vector to 31th Vector. Then, 31 linear sum signals Yi (i = 1, 2,..., 31) are output from the differential amplifier 1012b.

Subsequently, the touch panel controller 1010 performs an inner product operation of the linear sum signal Yi and the code series Di, 2 corresponding to the drive line DL1 within a range of 1 ≦ i ≦ 31. That is, the touch panel controller 1010 calculates the following formula (3).

Here, in the code sequence generated based on the M-sequence code MC1, the inner product value between the same code sequences is equal to the sequence length N, and the inner product value between different code sequences is -1. Is known.

Therefore, considering that the sequence length N = 31, the following equation (4) is derived in the equation (3) based on the above-described mathematical property.

Further, consider a case where all drive lines (ie, DL1 to DL4) and all sense lines (ie, SL1 to SL4) are manufactured to have uniform widths.

At this time, it can be assumed that the values of the capacitances C31 to C44 are substantially equal. Therefore, in Expression (4), the first term on the right side, that is, 31 × (C31-C41) is the second term on the right side (C32-C42), the third term on the right side (C33-C43), and the fourth term on the right side ( It can be said that it has a sufficiently large value as compared with each of C34-C44). For this reason, an approximate expression represented by the following expression (5) is derived based on the expression (4).

Therefore, the touch panel controller 1010 can estimate the capacitance (C31-C41) on the right side based on the inner product calculation on the left side.

(Error included in capacitance estimation in touch panel system 1000)
In the touch panel system 1000, when an input is made to the touch panel 1020 before N times of driving for the M drive lines are completed, the estimated capacitance value includes an error that cannot be ignored. There is a problem. The reason for this will be described mathematically below. Here, M = 4 and N = 31.

Also, for the sake of simplicity, consider the case of C32 = C42 = C33 = C43 = C34 = C44 = 0 in equation (3). That is, in the expression (3), attention is focused on the first term on the right side relating to the capacitance (C31-C41).

(Driving from the first to 31st drive lines DL1 to DL4)
Now, (i) in the driving of the drive lines DL1 to DL4 from the first time to the tenth time, no input is given to the touch panel 1020, and (ii) the drive lines DL1 to DL4 from the 11th time to the 31st time are supplied. It is assumed that an input to the touch panel 1020 is given in driving.

Further, it is assumed that the change amount of the capacitance C31 is changed by ΔC by the input to the touch panel 1020 in the drive of the drive lines DL1 to DL4 from the 11th to the 31st. For this reason, in the drive of the drive lines DL1 to DL4 from the 11th time to the 31st time, the capacitance C31 is replaced with (C31 + ΔC).

Therefore, based on the equation (3), the estimated value of the capacitance (C31-C41) in driving the drive lines DL1 to DL4 from the first time to the 31st time is expressed as the following (6).

Equation (6) indicates that an amount caused by the change amount ΔC of the capacitance C31 is included in the estimated value of the capacitance (C31-C41).

In Equation (6), the first term on the right side is more dominant than the second term on the right side. Therefore, an estimated value of the capacitance (C31-C41) may be calculated based on the equation (6).

Next, consider the inner product operation of the linear sum signal Yi and the code sequence Di, 2 corresponding to the drive line DL2 shown in the following equation (7). Equation (7) shows the inner product calculation for estimating the value of the capacitance (C32-C42).

Similarly to Expression (6), the following Expression (8) is derived by modifying Expression (7) based on C32 = C42 = C33 = C43 = C34 = C44 = 0.

The magnitude (absolute value) of the first term on the right side of Equation (8) is 1/31 of the magnitude (absolute value) of the first term on the right side of Equation (6), and can be regarded as a minute amount. it can. Therefore, in Equation (8), the first term on the right side relating to the capacitance (C31-C41) can be ignored as it is substantially equal to zero.

On the other hand, in Expression (8), the second term on the right side related to the change amount ΔC may be a size that cannot be ignored. Therefore, according to the assumption that C32 = C42 = 0, the true value of the capacitance (C32−C42) is 0, but the capacitance (C32−C42−) based on the inner product calculation shown in Expression (8). The estimated value of C42) may not be zero.

In this case, although the capacitance value (C32-C42) is actually 0, it is assumed that there is a capacitance value depending on the change amount ΔC, and the capacitance (C32-C42). The value of is estimated incorrectly.

(Driving drive lines DL1 to DL4 from the 32nd to 62nd times)
Next, consider a case where the input to the touch panel 1020 in the drive of the drive lines DL1 to DL4 from the 11th to the 31st time is continued in the drive of the drive lines DL1 to DL4 from the 32nd to the 50th.

That is, (i) in driving the drive lines DL1 to DL4 from the 32nd to 50th times, an input to the touch panel 1020 is given, and (ii) driving the drivelines DL1 to DL4 from the 51st to the 62nd time Suppose that no input is given to the touch panel 1020.

Therefore, in the drive of the drive lines DL1 to DL4 from the 32nd time to the 50th time, the change amount ΔC of the capacitance C31 exists, and the capacitance C31 is replaced by (C31 + ΔC). On the other hand, in the drive of the drive lines DL1 to DL4 from the 51st time to the 62nd time, the change amount ΔC of the capacitance C31 does not exist.

Also, for driving the drive lines DL1 to DL4 from the 32nd time to the 62nd time, the signals 1st Vector to 31th Vector are used in order as in the drive lines DL1 to DL4 from the 1st time to the 31st time.

Therefore, the 32nd drive lines DL1 to DL4 are driven using the signal 1st Vector, and the 62nd drive lines DL1 to DL4 are driven using the signal 31st Vector.

That is, the (j + 31) th drive lines DL1 to DL4 are driven using the jth signal jth Vector (1 ≦ j ≦ 31). In other words, the (i-31) th signal (i-31) th Vector is used to drive the i-th (32 ≦ i ≦ 62) drive lines DL1 to DL4.

Therefore, similarly to the equation (3), the estimated value of the capacitance (C31-C41) in driving the drive lines DL1 to DL4 from the 32nd to the 62nd is expressed as the following equation (9).

Similarly to Equation (6), Equation (9) also includes an amount caused by the change amount ΔC of the capacitance C31 with respect to the estimated value of the capacitance (C31-C41).

Note that, similarly to Equation (6), in Equation (9), the first term on the right side is more dominant than the second term on the right side. Therefore, an estimated value of the capacitance (C31-C41) may be calculated based on the equation (9).

Similarly to the equation (8), the estimated value of the capacitance (C32-C42) in driving the drive lines DL1 to DL4 from the 32nd time to the 62nd time is expressed as the following equation (10).

Similarly to the equation (8), also in the equation (10), the second term on the right side relating to the change amount ΔC may be a size that cannot be ignored.

Therefore, similarly to the equation (8), in the equation (10), the capacitance value (C32-C42) is actually 0, but the capacitance value depending on the change amount ΔC is 0. In some cases, the value of the capacitance (C32-C42) is estimated incorrectly.

Japanese Patent Publication “Japanese Patent Laid-Open No. 2013-3603 (published on January 7, 2013)”

As described above, in the touch panel system 1000 disclosed in Patent Document 1, when the input to the touch panel 1020 is performed before N times of driving for the M drive lines are completed, the estimated capacitance value May include an error that cannot be ignored.

For this reason, there is a problem that an erroneous estimation of the capacitance is made assuming that the capacitance has changed at a position on the touch panel 1020 where the capacitance has not actually changed.

The present invention has been made to solve the above problem, and an object of the present invention is to provide a touch panel controller capable of estimating the capacitance more accurately.

In order to solve the above-described problem, a touch panel controller according to an aspect of the present invention performs M drive lines (M is an integer of 2 or more) N times based on a code sequence having a sequence length N (N is an integer). A drive unit that outputs N linear sum signals relating to M capacitances respectively formed at intersections of the M drive lines and one sense line by driving; After holding the N linear sum signals, K linear sum signals are obtained each time the driving unit drives the drive line K times (K is an integer satisfying 0 <K <N). By sequentially updating with K linear sum signals, N output signals consisting of K updated linear sum signals and (NK) pre-update linear sum signals are output. Signal processing unit and the N output signals By performing inner product calculation of the code sequence is characterized in that it comprises a, and the inner product calculation unit for calculating an electrostatic capacitance estimate as an estimate of the value of the M capacitance.

The touch panel controller according to one aspect of the present invention has an effect that the capacitance can be estimated more accurately.

It is a figure which shows the structure of the touchscreen system which concerns on Embodiment 1 of this invention. It is a figure showing an example of 1 composition of a touch panel system concerning Embodiment 1 of the present invention. In the touch panel system which concerns on Embodiment 1 of this invention, it is a figure showing the value of the output signal acquired in the timing of each predetermined | prescribed clock signal. In the touch panel system which concerns on Embodiment 1 of this invention, it is a figure showing the estimated value of the difference of the electrostatic capacitance calculated in the timing of each predetermined | prescribed clock signal. It is a functional block diagram which shows the structure of the mobile telephone which concerns on Embodiment 2 of this invention. It is a figure which shows the example of 1 structure of the touchscreen system disclosed by patent document 1. FIG. In the touch panel system disclosed by patent document 1, it is a figure which shows the M series code | symbol for producing | generating the code series used for the drive of a drive line.

[Embodiment 1]
The first embodiment of the present invention will be described with reference to FIGS. 1 to 4 as follows.

(Configuration of touch panel system 100)
FIG. 1 is a diagram illustrating a configuration of a touch panel system 100 according to the present embodiment. The touch panel system 100 includes a touch panel controller 110 and a touch panel 120.

(Touch panel 120)
The touch panel 120 includes M (M is an integer of 2 or more) drive lines DL1 to DLM arranged in parallel with each other along the vertical direction, and P (P is a parallel display) arranged in parallel with each other along the horizontal direction. (Integer greater than or equal to 1) sense lines SL1 to SLP.

In the touch panel 120, (P × M) electrostatic capacitances C1, 1 to CP, M are formed at the intersections of the drive lines DL1 to DLM and the sense lines SL1 to SLP. Here, the capacitances CP and M represent the capacitance formed at the intersection of the sense line SLP and the drive line DLM.

(Touch panel controller 110)
The touch panel controller 110 includes a drive unit 111. The touch panel controller 110 includes differential amplifiers 112a and 112b, AD (Analog-Digital) converters 113a and 113b, signal processors 114a and 114b, inner product arithmetic units 115a and 115b, and estimated value evaluation units 116a and 116b. ing.

Note that each of the differential amplifiers 112a and 112b, the AD conversion units 113a and 113b, the signal processing units 114a and 114b, the inner product calculation units 115a and 115b, and the estimated value evaluation units 116a and 116b are sense lines SL1 to SL provided in the touch panel 120. Depending on the number P of SLPs, three or more may be provided. In FIG. 1, as representative members, differential amplifiers 112a and 112b, AD conversion units 113a and 113b, signal processing units 114a and 114b, inner product calculation units 115a and 115b, and estimated value evaluation units 116a and 116b, respectively, It is shown in the figure.

(Driver 111)
The driving unit 111 drives the drive lines DL1 to DLM based on the code sequence Drive1 to DriveN having the sequence length N. The code sequences Drive1 to DriveN may be generated by, for example, the M sequence code MC1 shown in FIG.

Here, among the code sequences Drive1 to DriveN, the drive lines DL1 to DLM are driven based on the code sequences Drive1 to DriveM.

Further, in the i-th (1 ≦ i ≦ N) driving of the drive line, signals 1st Vector to Nth Vector that specify the value of the voltage to be applied to each drive line are also represented by, for example, M It may be defined by the sequence code MC1 or the like.

The drive unit 111 includes switches D1 to DM and DB1 to DBM. The drive unit 111 applies the voltage Vdrive to the Xth drive line DLX via the Xth switch DX. In addition, the drive unit 111 applies a voltage (−Vdrive) to the Xth drive line DLX via the Xth switch DBX.

The driving unit 111 applies the voltage Vdrive to the Xth drive line DLX when the component of the Xth signal DriveX is “1” in the i-th driveline drive. The drive unit 111 applies a voltage (−Vdrive) to the Xth drive line DLX when the component of the Xth signal DriveX is “−1”.

The voltage Vdrive may be a power supply voltage applied to the touch panel system 100, for example. Further, as the voltage Vdrive, a voltage other than the power supply voltage such as a reference voltage applied to the touch panel system 100 may be used.

Hereinafter, the respective components of the code sequences Drive1 to DriveM in the driving of the drive lines DL1 to DLM for the i (1 ≦ i ≦ N) times are represented as code sequences Di, 1 to Di, M. Each of the code sequences Di, 1 to Di, M preferably has a small correlation with each other.

(Differential amplifiers 112a and 112b)
The differential amplifiers 112a and 112b are two-input two-output amplifiers, amplify the difference between the two input signals, and output as an output signal.

The differential amplifiers 112a and 112b are each connected to two integration capacitors Cint. That is, one of the integration capacitors Cint is connected between one input terminal and one output terminal of the differential amplifier 112a or 112b. The other one of the integration capacitors Cint is connected between the other input terminal and the other output terminal of the differential amplifier 112a or 112b.

The differential amplifier 112b is arranged such that signals acquired from the sense lines SL1 and SL2 are input thereto. The differential amplifier 112b includes an input signal from the sense line SL1 (linear sum signal relating to capacitance formed at the intersection of the sense line SL1 and the drive lines DL1 to DLM) and an input signal from the sense line SL2 (sense line). The difference between the SL2 and the linear sum signal relating to the capacitance formed at the intersections of the drive lines DL1 to DLM) is amplified, and a linear sum signal as an output signal is given to the AD converter 113b.

Similarly, the differential amplifier 112a is arranged so that signals acquired from the sense lines SL (P-1) and SLP are respectively input thereto. The differential amplifier 112a includes an input signal from the sense line SL (P-1) (a linear sum signal related to the capacitance formed at the intersection of the sense line SL (P-1) and the drive lines DL1 to DLM), Amplifies the difference from the input signal from the sense line SLP (linear sum signal related to the capacitance formed at the intersection of the sense line SLP and the drive lines DL1 to DLM), and AD converts the linear sum signal as the output signal To the part 113a.

( AD converters 113a and 113b)
The AD converters 113a and 113b perform AD conversion on the linear sum signals output from the differential amplifiers 112a and 112b as analog signals, respectively. Subsequently, the AD conversion units 113a and 113b supply the digitized linear sum signals to the signal processing units 114a and 114b, respectively.

The linear sum signal is supplied as a digital signal from the AD conversion units 113a and 113b to the signal processing units 114a and 114b, whereby the capacitance distribution in the signal processing units 114a and 114b and the inner product calculation units 115a and 115b is changed. Various operations for calculation are facilitated.

( Signal processing units 114a and 114b)
The signal processing units 114a and 114b temporarily hold the value of the linear sum signal provided from the AD conversion units 113a and 113b in each drive of the drive lines DL1 to DLM, respectively. Subsequently, the signal processing units 114a and 114b give the values of the linear sum signals necessary for the inner product calculation for estimating the capacitance value to the inner product calculation units 115a and 115b, respectively.

That is, the signal processing units 114a and 114b hold the linear sum signals Y1 to YN obtained by driving the N drive lines DL1 to DLM.

Each time the drive lines DL1 to DLM are driven K times (K is an integer satisfying 0 <K <N), the signal processing units 114a and 114b pass through the AD conversion units 113a and 113b to obtain the latest K The linear sum signals Y2 (1) to Y2 (K) are obtained.

Subsequently, the signal processing units 114a and 114b use the K linear sum signals (that is, Y1 to YK) among the held linear sum signals Y1 to YN as the latest K linear sum signals Y2 (1 ) To Y2 (K). Here, (NK) linear sum signals (that is, Y (K + 1) to YN) among the held linear sum signals Y1 to YN are not updated.

The signal processing units 114a and 114b then hold the K linear sum signals Y2 (1) to Y2 (K) and (NK) linear sum signals Y (K + 1) to YN that are currently held. N linear sum signals consisting of are given as output signals to the inner product calculation sections 115a and 115b.

Note that the integer K that defines the number of linear sum signals to be updated may be a specific value predetermined in the touch panel system 100, or may be a processor provided outside the touch panel system 100 (for example, It may be a value that can be changed by a CPU 310 in FIG.

(Inner product calculation units 115a and 115b)
The inner product calculation units 115a and 115b are calculation units that perform an inner product calculation for estimating a capacitance value. That is, the inner product calculation units 115a and 115b calculate the inner product of the N output signals (linear sum signals) given from the signal processing units 114a and 114b and any one of the code sequences Di, 1 to Di, M. I do. Subsequently, the inner product calculation units 115a and 115b provide the estimated value of the capacitance obtained as a result of the inner product calculation to the estimated value evaluation units 116a and 116b, respectively.

The code sequences Di, 1 to Di, M may be given from the signal processing units 114a and 114b to the inner product calculation units 115a and 115b, or may be held in advance in the inner product calculation units 115a and 115b. Also good.

(Estimated value evaluation units 116a and 116b)
The estimated value evaluation units 116a and 116b perform evaluation on a plurality of estimated capacitance values obtained as a result of the inner product calculation in the inner product calculation units 115a and 115b, respectively. Subsequently, the estimated value evaluation units 116a and 116b determine the estimated value of the capacitance with the least error based on the evaluation result.

For example, the estimated value evaluation units 116a and 116b perform evaluation on the estimated values of the plurality of capacitances by calculating standard deviations or variances of the estimated values of the plurality of capacitances. Then, the estimated value evaluation units 116a and 116b use the estimated value of the capacitance with the smallest standard deviation or variance as the representative value of the estimated values of the plurality of capacitances (that is, the estimated value of the capacitance with the least error). ).

(Explanation of capacitance estimation in touch panel system 100)
Next, the estimation of the capacitance in the touch panel system 100 of the present embodiment will be mathematically described. The specific configuration and operation of the touch panel system 100 that estimates the capacitance based on the method described here will be described in detail later (see FIG. 2 described later).

Here, description will be made by comparison with the touch panel system 1000 disclosed in Patent Document 1. That is, as in the description of the operation of the touch panel system 1000, consider the case where M = 4, N = 31, and C32 = C42 = C33 = C43 = C34 = C44 = 0. Further, consider the case where the number K of linear sum signals to be updated in the signal processing units 114a and 114b is set as K = 1.

Similarly to the description of the operation of the touch panel system 1000, in the drive of the drive lines DL1 to DL4 from the first time to the 62nd time, in the drive of the drive lines DL1 to DL4 from the 11th time to the 50th time, Assume that the change amount of the capacitance C31 is changed by ΔC.

(Driving from the first to 31st drive lines DL1 to DL4)
In the touch panel system 100, 31 linear sum signals Y1 to Y31 are newly obtained through driving of the drive lines DL1 to DL4 from the first time to the 31st time.

At the time of driving the drive lines DL1 to DL4 from the first time to the 31st time, the touch panel controller 110 of the present embodiment is similar to the touch panel controller 1010 provided in the touch panel system 1000 of Patent Document 1 to estimate the capacitance. To calculate the inner product.

Therefore, in the touch panel controller 110, the inner product calculation for estimating the capacitance (C31-C41) is performed by the equation (6). In addition, in the touch panel controller 110, the inner product calculation for estimating the capacitance value (C32-C42) is performed by Expression (8).

Note that a linear sum signal obtained at the i-th (1 ≦ i ≦ 31) is expressed as Yi when the drive lines DL1 to DL4 are driven from the first to the 31st. In addition, since the calculation process until the expressions (6) and (8) are derived has already been described in the touch panel system 1000 of Patent Document 1, detailed description thereof is omitted.

(When driving the drive lines DL1 to DL4 for the 32nd time)
Next, consider the 32nd drive lines DL1 to DL4 in the touch panel system 100.

When driving the drive lines DL1 to DL4 for the 32nd time, the touch panel controller 110 determines the output signal Y2i based on the following equation (11) with respect to the linear sum signal Yi.

That is, in the output signal Y2i, the linear sum signal Y1 obtained in the first drive lines DL1 to DL4 is updated to the linear sum signal Y32 obtained in the 32nd drive line DL1 to DL4 drive. . On the other hand, the linear sum signals Y2 to Y31 obtained in the drive of the drive lines DL1 to DL4 from the second time to the 31st time are held as they are.

Then, the touch panel controller 110 performs an inner product operation for estimating the capacitance (C31-C41) based on the output signal Y2i instead of the linear sum signal Yi. When driving the drive lines DL1 to DL4 for the 32nd time, the inner product calculation for estimating the capacitance (C31-C41) based on the output signal Y2i is expressed by the following equation (12).

The coefficient of the second term on the right side related to the change amount ΔC of the capacitance C31 in Expression (12) (that is, 22) is the coefficient of the second term on the right side related to the change amount ΔC of the capacitance C31 in Expression (6). Compared with 21) by one.

This is because, in the output signal Y2i, the linear sum signal Y1 obtained in the first drive when the input to the touch panel 120 is not given is the linear sum obtained in the 32nd drive where the input to the touch panel 120 is given. This is because the signal Y32 is replaced.

(During 41st drive line DL1-DL4 drive)
Further, consider the 41st driving of the drive lines DL1 to DL4 in the touch panel system 100.

When the drive lines DL1 to DL4 are driven for the 41st time, the output signal Y2i is determined by the touch panel controller 110 according to the following equation (13).

That is, in the output signal Y2i, the linear sum signal Y1 obtained in the driving of the drive lines DL1 to DL4 from the first time to the tenth time is the linear obtained in the driving of the drive lines DL1 to DL4 from the 32nd time to the 41st time. The sum signals Y32 to Y41 are updated. On the other hand, the linear sum signals Y2 to Y31 obtained in the drive of the drive lines DL1 to DL4 from the 11th time to the 31st time are held as they are.

When the drive lines DL1 to DL4 are driven for the 41st time, the inner product calculation for estimating the capacitance (C31-C41) based on the output signal Y2i is expressed by the following equation (14).

According to the equation (14), in the output signal Y2i, the linear sum signals Y1 to Y10 obtained in the driving of the drive lines DL1 to DL4 from the first time to the tenth time are obtained from the drive lines DL1 to DL4 of the 32nd to 41st times. The linear sum signals Y32 to Y41 obtained in driving are updated. On the other hand, the linear sum signals Y11 to Y31 obtained in the drive of the drive lines DL1 to DL4 from the 11th time to the 31st time are held as they are.

In Equation (14), the coefficient of the second term on the right side (ie, 31) related to the change amount ΔC of the capacitance C31 is equal to the coefficient (ie, 31) of the first term on the right side related to the capacitance (C31−C41). .

This is because, in the output signal Y2i, the linear sum signals Y1 to Y10 obtained in the first to tenth driving when the input to the touch panel 120 is not given are the 32nd to 41th when the input to the touch panel 120 is given. This is because the linear sum signals Y32 to Y41 obtained in the previous driving are replaced.

On the other hand, when the drive lines DL1 to DL4 are driven for the 41st time, the inner product calculation for estimating the capacitance (C32-C42) based on the output signal Y2i is expressed by the following equation (15).

According to the equation (15), in the output signal Y2i, the linear sum signals Y1 to Y10 obtained by driving the drive lines DL1 to DL4 from the first time to the tenth time are represented by the 32 to 41st drive lines DL1 to DL4. The linear sum signals Y32 to Y41 obtained in driving are updated. On the other hand, the linear sum signals Y11 to Y31 obtained in the drive of the drive lines DL1 to DL4 from the 11th time to the 31st time are held as they are.

In equation (15), the coefficient of the second term on the right side (that is, −1) related to the change amount ΔC of the capacitance C31 is the coefficient of the first term on the right side related to the capacitance (C32−C42) (ie, − Equivalent to 1).

Therefore, the magnitude of the second term on the right side related to the change ΔC in equation (15) is even smaller than in equations (8) and (10).

That is, in the equation (15), the magnitude of the error due to the change amount ΔC included in the capacitance value (C32-C42) is suppressed as compared with the equations (8) and (10). Has been.

For this reason, according to the touch panel system 100 of the present embodiment, it is possible to suppress erroneous estimation of the capacitance at the position of the touch panel where the capacitance does not actually change.

(Touch panel system 100s as one configuration example of touch panel system 100)
An example of a specific configuration and operation of the touch panel system 100 will be described with reference to FIG. FIG. 2 is a diagram illustrating a configuration example of the touch panel system 100.

FIG. 2 shows a configuration of the touch panel system 100s in the case where M = 18 and P = 2 in the touch panel system 100 shown in FIG. The touch panel system 100s includes a touch panel controller 110s and a touch panel 120s.

The touch panel 120s includes 18 drive lines DL1 to DL18 and two sense lines SL1 to SL2. Then, 36 electrostatic capacitances C1, 1 to C2, 18 are formed at the intersections of the drive lines DL1 to DL18 and the sense lines SL1 to SL2, respectively.

Here, it is assumed that each of the capacitances C1, 1 to C2, 18 has a capacitance of C = 2.2 pF. Further, it is assumed that the capacitance change amount ΔC generated in each of the capacitances C1, 1 to C2, 18 when the input is given to the touch panel 120s is ΔC = −0.2 pF.

Further, the touch panel controller 110s includes a drive unit 111s, a differential amplifier 112s, an AD conversion unit 113s, a signal processing unit 114s, an inner product calculation unit 115s, and an estimated value evaluation unit 116s.

It is assumed that the frequency of the clock signal given to the touch panel controller 110s is 1 MHz. Further, it is assumed that the power supply voltage VDD and the common mode voltage VCM supplied to the touch panel controller 110s are VDD = 3.3V and VCM = 1.65V, respectively.

The driving unit 111s corresponds to the driving unit 111 in the case of M = 18 in the touch panel system 100 in FIG. 1, and drives the drive lines DL1 to DL18. That is, the drive unit 1011 includes switches D1 to D18 and DB1 to DB18.

In the driving unit 111s, Vdrive = (VDD / 2) + VCM = 3.3V. Further, in the driving unit 111s, −Vdrive = (− VDD / 2) + VCM = 0V.

The differential amplifier 112s, the AD conversion unit 113s, the signal processing unit 114s, the inner product calculation unit 115s, and the estimated value evaluation unit 116s are arranged so as to process signals from the sense lines SL1 and SL2. Corresponds to the AD conversion unit 113b, the signal processing unit 114b, the inner product calculation unit 115b, and the estimated value evaluation unit 116s, respectively.

(Specific example of operation of touch panel system 100s)
Consider a case where 63 code sequences generated by bit-shifting an M-sequence code having a sequence length of 63 are used in touch panel controller 110s.

The 63 code sequences corresponding to the t-th clock signal given to the touch panel controller 110s are referred to as DM1, t to DM63, t. The code sequences DM1, t to DM63, t have different values for each clock frequency t. The sequence length N of the code sequences DM1, t to DM63, t is N = 63.

In particular, the code sequence corresponding to the first clock signal is represented as DM1,1 to DM63,1, and the code sequence corresponding to the 63rd clock signal is represented as DM1,63 to DM63,63. .

The code sequences DM1, t to DM63, t repeat the same value every 63 clocks. Accordingly, at t = 64th time, DM1, t to DM63, t = DM1, 64 to DM63, 64 = DM1, 1 to DM63,1. That is, the code sequences DM1, 64 to DM63, 64 corresponding to the 64th clock signal are equal to the code sequences DM1, 1 to DM63,1 corresponding to the first clock signal.

First, consider the period from the first clock signal to the 63rd clock signal. The signal processing unit 114s acquires the linear sum signal Y1 (t) in the t-th clock signal that satisfies 1 ≦ t ≦ 63. When the 63rd clock signal is given, the signal processing unit 114s holds 63 linear sum signals from Y1 (1) to Y1 (63).

Hereinafter, the 63 linear sum signals held by the signal processing unit 114s are expressed as output signals YM (j). j is an integer satisfying 1 ≦ j ≦ N, and here 1 ≦ j ≦ 63. The signal processing unit provides the output signal YM (j) to the inner product calculation unit 115s.

Since the update of the linear sum signal has not been performed at the time when the 63rd clock signal is given, YM (j) = Y1 (j). Hereinafter, a case where K = 10 is set in the signal processing unit 114s will be considered.

Next, the case where the input to the touch panel 120s is given near the intersection of the sense line SL1 and the drive line DL11 in the period from the 28th clock signal to the 100th clock signal is illustrated.

In this case, during the period from the 28th clock signal to the 100th clock signal, the values of the capacitances C1 and C11 are replaced from 2.2 pF (= C) to 2.0 pF (= C + ΔC).

3A to 3H are graphs showing the values of the output signals YM (j) (that is, the values of YM (1) to YM (63)) acquired at the timing of each predetermined clock signal. Indicates. The horizontal axis indicates the value of the integer j. The vertical axis indicates the value of the output signal YM (j). The output signal YM (j) is a physical quantity with the voltage (V) as a unit.

(A) of FIG. 3 shows the value of the output signal YM (j) when the 63rd clock signal is given. Then, in the range of 1 ≦ j ≦ 27 (that is, the period when the input to the touch panel 120s is not given), Y1 (j) = 0, so YM (j) = 0.

(B) of FIG. 3 shows the value of the output signal YM (j) when the 73rd clock signal is given. In the range of 64 ≦ j ≦ 73, the output signal YM (j) is updated by the linear sum signal Y1 (j−63) as YM (j−63) = Y1 (j).

In the range of 64 ≦ j ≦ 73 (that is, the period when the input to the touch panel 120s is given), Y1 (j) ≠ 0, so YM (j−63) ≠ 0. Therefore, by replacing (j-63) with j, it can be said that YM (j) ≠ 0 in the range of 1 ≦ j ≦ 10. Therefore, the range of j where YM (j) = 0 is 11 ≦ j ≦ 27.

(C) of FIG. 3 shows the value of the output signal YM (j) when the 83rd clock signal is given. In the range of 74 ≦ j ≦ 83, the output signal YM (j) is updated by the linear sum signal Y1 (j−63) as YM (j−63) = Y1 (j).

And, in the range of 74 ≦ j ≦ 83 (that is, the period when the input to the touch panel 120s is given), Y1 (j) ≠ 0, so YM (j−63) ≠ 0. Therefore, by replacing (j−63) with j, YM (j) ≠ 0 in the range of 11 ≦ j ≦ 20. Therefore, the range of j where YM (j) = 0 is 21 ≦ j ≦ 27.

(D) of FIG. 3 shows the value of the output signal YM (j) at the time when the 93rd clock signal is given. In the range of 84 ≦ j ≦ 93, the output signal YM (j) is updated by the linear sum signal Y1 (j−63) as YM (j−63) = Y1 (j).

In the range of 84 ≦ j ≦ 93 (that is, the period when the input to the touch panel 120s is given), Y1 (j) ≠ 0, so YM (j−63) ≠ 0. Therefore, by replacing (j−63) with j, YM (j) ≠ 0 in the range of 21 ≦ j ≦ 30. Therefore, there is no j range where YM (j) = 0.

(E) of FIG. 3 shows the value of the output signal YM (j) when the 103rd clock signal is given. In the range of 94 ≦ j ≦ 103, the output signal YM (j) is updated by the linear sum signal Y1 (j−63) as YM (j−63) = Y1 (j).

In the range of 94 ≦ j ≦ 99 (that is, the period when the input to the touch panel 120s is given), Y1 (j) ≠ 0, so YM (j−63) ≠ 0. Therefore, by replacing (j−63) with j, YM (j) ≠ 0 in the range of 31 ≦ j ≦ 36.

On the other hand, YM (j−63) = 0 because Y1 (j) = 0 in the range of 100 ≦ j ≦ 103 (that is, the period when the input to the touch panel 120s is not given). Therefore, by replacing (j−63) with j, YM (j) = 0 within the range of 37 ≦ j ≦ 40.

(F) in FIG. 3 shows the value of the output signal YM (j) when the 113th clock signal is given. In the range of 104 ≦ j ≦ 113, the output signal YM (j) is updated by the linear sum signal Y1 (j−63) as YM (j−63) = Y1 (j).

In the range of 104 ≦ j ≦ 113 (that is, a period when no input is given to the touch panel 120s), Y1 (j) = 0, so YM (j−63) = 0. Therefore, by replacing (j−63) with j, YM (j) = 0 in the range of 41 ≦ j ≦ 50. Therefore, the range of j where YM (j) = 0 is 37 ≦ j ≦ 50.

(G) in FIG. 3 shows the value of the output signal YM (j) at the time when the 123rd clock signal is given. In the range of 114 ≦ j ≦ 123, the output signal YM (j) is updated by the linear sum signal Y1 (j−63) as YM (j−63) = Y1 (j).

In the range of 114 ≦ j ≦ 123 (that is, a period when no input is given to the touch panel 120s), Y1 (j) = 0, so YM (j−63) = 0. Therefore, by replacing (j−63) with j, YM (j) = 0 in the range of 51 ≦ j ≦ 60. Therefore, the range of j where YM (j) = 0 is 37 ≦ j ≦ 60.

(F) in FIG. 3 shows the value of the output signal YM (j) when the 126th clock signal is given. In the range of 124 ≦ j ≦ 126, the output signal YM (j) is updated by the linear sum signal Y1 (j−63) as YM (j−63) = Y1 (j).

In the range of 124 ≦ j ≦ 126 (that is, the period when no input is given to the touch panel 120s), Y1 (j) = 0, so YM (j−63) = 0. Therefore, by replacing (j−63) with j, YM (j) ≠ 0 in the range of 61 ≦ j ≦ 63. Therefore, the range of j where YM (j) = 0 is 37 ≦ j ≦ 63.

(A) to (h) of FIG. 4 are graphs showing estimated values of the difference in capacitance calculated at the timing of each predetermined clock signal. The horizontal axis shows each of the 18 types of capacitance differences from the capacitance difference (C1, 1-C2, 1) to the capacitance difference (C1, 18-C2, 18). Yes. The vertical axis shows the estimated value of the difference in capacitance corresponding to the horizontal axis as a physical quantity in units of capacitance (pF).

Thereafter, at the timing of each clock signal, based on the output signals YM (1) to YM (63) given from the signal processing unit 114s, the difference in capacitance (C1, C1) obtained as a result of calculation by the inner product calculation unit 115s Focus on the estimated value of 1-C2,1).

(A) of FIG. 4 shows the estimated value of the difference in capacitance when the 63rd clock signal is given. The estimated value of the difference in capacitance (C1, 1-C2, 1) is 0.105 pF.

(B) of FIG. 4 shows the estimated value of the difference in capacitance when the 73rd clock signal is given. The estimated value of the difference in capacitance (C1, 1-C2, 1) is 0.137 pF.

(C) of FIG. 4 shows the estimated value of the difference in capacitance at the time when the 83rd clock signal is given. The estimated value of the difference in capacitance (C1, 1-C2, 1) is 0.169 pF.

(D) of FIG. 4 shows the estimated value of the difference in capacitance at the time when the 93rd clock signal is given. The estimated value of the difference in capacitance (C1, 1-C2, 1) is 0.193 pF.

FIG. 4 (e) shows the estimated value of the difference in capacitance when the 103rd clock signal is given. The estimated value of the difference in capacitance (C1,1-C2,1) is 0.185 pF.

(F) of FIG. 4 shows the estimated value of the difference in capacitance at the time when the 113th clock signal is given. The estimated value of the difference in capacitance (C1, 1-C2, 1) is 0.154 pF.

(G) of FIG. 4 shows the estimated value of the difference in capacitance at the time when the 123rd clock signal is given. The estimated value of the difference in capacitance (C1, 1-C2, 1) is 0.123 pF.

(H) of FIG. 4 shows the estimated value of the difference in capacitance when the 126th clock signal is given. The estimated value of the difference in capacitance (C1, 1-C2, 1) is 0.114 pF.

The inner product calculation unit 115s gives the estimated values of the 18 differences in capacitance shown in each of (a) to (h) of FIG. 4 to the estimated value evaluation unit 116s. Then, the estimated value evaluating unit 116s calculates the standard deviation of the estimated values of the 18 different capacitance differences at the timing of each clock signal.

The standard deviation of the estimated value of the difference in capacitance at the time when the 63rd clock signal is given as shown in FIG. 4 (a) is 0.0125 pF.

The standard deviation of the estimated value of the difference in capacitance when the 73rd clock signal is given as shown in FIG. 4B is 0.0121 pF.

4 (c), the standard deviation of the estimated value of the difference in capacitance at the time when the 83rd clock signal is given is 0.0083 pF.

4 (d), the standard deviation of the estimated value of the difference in capacitance when the 93rd clock signal is given is 0.000 pF.

The standard deviation of the estimated value of the difference in capacitance at the time when the 103rd clock signal is given as shown in (e) of FIG. 4 is 0.003 pF.

The standard deviation of the estimated value of the difference in capacitance at the time when the 113th clock signal shown in FIG. 4 (f) is given is 0.0094 pF.

4 (g), the standard deviation of the estimated value of the difference in capacitance when the 123rd clock signal is given is 0.0103 pF.

4 (h), the standard deviation of the estimated value of the difference in capacitance at the time when the 126th clock signal is given is 0.0109 pF.

The estimated value evaluating unit 116s compares the standard deviations of the estimated values of the difference in capacitance between the 64th and 126th clock signals.

Then, the estimated value evaluating unit 116s obtains the estimated value of the difference in capacitance from the 64th time to the 126th time when the 93rd clock signal is given, in which the standard deviation of the estimated value of the difference in capacitance is minimized. It is determined as a representative value of the estimated value of the difference in capacitance when the clock signal is given 63 times until the first time.

That is, the estimated value evaluating unit 116s sets the estimated value (C1, 1−C2, 1) = 0.193 pF of the difference in capacitance when the 93rd clock signal is given from the 64th to the 126th time. , 63 as the representative value of the estimated value of the difference in capacitance at the time when the clock signal is given 63 times.

In other words, the estimated value evaluating unit 116s determines the electrostatic capacitance difference estimated value when the 63rd clock signal is given from the 64th time to the 126th time as the static value when the 93rd clock signal is given. It is determined that the estimated value of the difference in electric capacity is (C1,1-C2,1) = 0.193 pF.

Note that the estimated value evaluating unit 116s may calculate the standard deviation only for the estimated value of the capacitance that is equal to or less than a predetermined capacitance threshold value TC (for example, ± 0.05 pF). Capacitance threshold TC may be a specific value determined in advance in touch panel system 100, or may be changed by a processor or the like provided outside touch panel system 100 (for example, CPU 310 in FIG. 5 described later). It may be a value.

Further, at the time when the first to 63rd clock signals are given, the output signal YM (j) is not updated every 10 times. For this reason, the estimated value evaluation unit 116s obtains the estimated value of the difference in capacitance at the time when the 63rd clock signal is given as the capacitance at the time when the first to 63rd clock signals are given. Determined as a representative value of the difference estimate

That is, the estimated value evaluating unit 116s obtains a representative value of the estimated value of the difference in capacitance at the time when 63 clock signals are given from the first time to the 63rd time as (C1, 1-C2, 1). = 0.105 pF.

As described above, in the touch panel system 100, it is possible to estimate the capacitance based on the code sequence of the sequence length N = 63 with higher accuracy.

[Modification]
In the first embodiment, the estimated value of the capacitance that minimizes the standard deviation is used as the representative value of the estimated value of the capacitance. On the other hand, an average value of the estimated capacitance value may be used as a representative value of the estimated capacitance value.

For example, as representative values of the estimated capacitance values from the 64th time to the 126th time, the static at the time when the 73rd, 83rd, 93rd, 103rd, 113th, 123rd, 126th clock signals are given. An average value of the estimated capacitance can be used.

In this case, the representative value of the estimated capacitance value (C1, 11-C2, 11) is 0.154 pF. Further, the standard deviation of the average value of the estimated capacitance value is 0.003 pF.

The standard deviation (0.003 pF) of the average value of the estimated capacitance value is the standard deviation (0.0109 pF) of the capacitance value when the 126th clock signal shown in the first embodiment is given. Smaller than. That is, by selecting the average value of the estimated capacitance values as the representative value of the estimated capacitance value, a more accurate capacitance value can be estimated.

In the first embodiment, the estimated value of the capacitance for each clock equal to the number of series length N is used as the output of the touch panel system 100s. On the other hand, it is good also as a structure which uses the estimated value of the electrostatic capacitance for every K times of clock as an output of the touch panel system 100s.

With the above-described configuration, the touch panel system 100 s outputs an estimated value of the capacitance every clock K times the sequence length N. For this reason, the touch panel system 100 s having the above-described configuration can cope with a signal (for example, a quick touch input) whose time change is fast.

The above effect will be described based on a comparison with the touch panel system 1000 disclosed in Patent Document 1. In the touch panel system 1000 disclosed in Patent Document 1, an estimated capacitance value is calculated every time the drive line is driven N times.

That is, in the touch panel system 1000, first, N linear sum signals S1,1, S1,2, S1,3,..., S1, (N−1), S1 obtained by driving the drive line N times. , N, an estimated capacitance value is calculated.

Then, based on the N linear sum signals S2,1, S2,2, S2,3,..., S2, (N-1), S2, N obtained by driving the drive line N times, The estimated capacitance value is calculated.

On the other hand, in the touch panel system 100s of the first embodiment, for example, consider a case where K = 1.

In the touch panel system 100s, first, N linear sum signals S1,1, S1,2, S1,3,..., S1, (N−1), S1, N obtained by driving the drive line N times. Is retained.

The already held linear sum signal S1,1 is updated by one latest linear sum signal S2,1 obtained by the next drive line drive. Then, the next estimated capacitance value is calculated based on the N linear sum signals S2,1, S1,2, S1,3,..., S1, (N-1), S1, N.

Therefore, in the touch panel system 100s, an estimated capacitance value is calculated for each driving of the drive line. For this reason, according to the touch panel system 100 s of the first embodiment, it is possible to cope with a signal that changes more rapidly than the touch panel system 1000 disclosed in Patent Document 1.

In the first embodiment, the signal processing unit 114s holds N linear sum signals and updates K linear sum signals every K clocks. On the other hand, the signal processing unit 114s may hold more than N linear sum signals and give N linear sum signals to the inner product operation unit 115s.

In the first embodiment, the case of K = 10 is exemplified, but the value of K may be appropriately selected according to the specification of the touch panel system 100 or 100s.

When the value of K is reduced, the linear sum signal is updated more frequently in the signal processing unit 114s. Accordingly, the touch panel system 100s can follow a signal that changes with time at a higher speed.

In addition, when the value of K is reduced, the inner product calculation unit 115s and the estimated value evaluation unit 116s require a larger number of calculations. Therefore, the touch panel system 100s with a small K value selected is mounted on a high-performance electronic device that can tolerate large power consumption and a large amount of memory consumption (or a large circuit area for mounting a memory). It is preferable.

On the other hand, when the value of K is increased, the followability to the signal of the touch panel system 100s is reduced, but there is an advantage that the number of calculations required in the inner product calculation unit 115s and the estimated value evaluation unit 116s is reduced.

Accordingly, the touch panel system 100s with a large K value selected is mounted on an electronic device that is driven by low power consumption and low memory consumption (or a small circuit area for mounting a memory) and does not particularly require high performance. It is preferred that

For this reason, in the touch panel system 100s, it is preferable to select a value of K in consideration of a trade-off between signal followability and required performance.

In particular, it is preferable to select a value of K in the range of “0 <K <N / 2”. This is because if “0 <K <N / 2”, the signal processing unit 114 s does not cause a situation in which part of the updated linear sum signal is further updated in the next update in the output signal. Because.

In the first embodiment, a code sequence based on the M sequence code is used. According to the M-sequence code, a code sequence can be easily generated by using a shift register connected in series. For this reason, when an M-sequence code is used, there is an advantage that a circuit for generating a code sequence can be easily configured.

On the other hand, in Embodiment 1, a code sequence may be generated based on other than the M sequence code. For example, a code sequence may be generated based on a Walsh code or a Hadamard code.

When a Walsh code or Hadamard code is used, the generated code sequence has a property that the correlation between codes is zero. In the code sequence based on the M sequence code, the correlation between codes is not zero.

For this reason, by using a code sequence based on Walsh code or Hadamard code, each drive line signal does not include an error caused by another drive line signal, and the accuracy of various calculations can be further improved. There is an advantage.

Note that when a Walsh code or Hadamard code is used, a code sequence cannot be easily generated using a shift register, unlike when an M-sequence code is used. For this reason, a memory for storing each component of the code sequence is further required, and an increase in circuit area for generating the code is required.

Accordingly, the touch panel system 100s using the code sequence based on the Walsh code or the Hadamard code is mounted on a high-performance electronic device that can tolerate a large amount of memory consumption (or a large circuit area for mounting the memory). It is preferable.

On the other hand, the touch panel system 100s using a code sequence based on an M-sequence code is mounted on an electronic device that is driven by a small memory consumption (or a small circuit area for mounting a memory) and does not particularly require high performance. It is preferable.

In the first embodiment, a differential amplifier (for example, differential amplifiers 112a, 112b, and 112s) is used as an amplifier that amplifies the linear sum output. In contrast, in the first embodiment, a single-ended amplifier may be used as the amplifier.

An integrated circuit including the touch panel controller 110 or 110s described in the first embodiment is also included in the technical scope of the present invention. Therefore, the touch panel controller 110 or 110s described in the first embodiment may be realized by an integrated circuit such as an IC (Integrated Circuit) chip.

[Embodiment 2]
The following will describe another embodiment of the present invention with reference to FIG. For convenience of explanation, members having the same functions as those described in the embodiment are given the same reference numerals, and descriptions thereof are omitted. FIG. 5 is a functional block diagram illustrating a configuration of a mobile phone 300 (electronic device) as an example of an electronic device including the touch panel system 100 described in the first embodiment.

The mobile phone 300 includes a CPU (Central Processing Unit) 310, a camera 313, a microphone 314, a speaker 315, an operation unit 316, a display panel 318, a display control circuit 309, a ROM (Read Only Memory) 311, and a RAM (Random Access Memory) 312. , And a touch panel system 100.

Each component included in the mobile phone 300 is connected to each other by a data bus. Although not shown in FIG. 6, the mobile phone 300 may be configured to include an interface for connecting to another electronic device by wire.

CPU 310 controls the operation of mobile phone 300. CPU 310 executes a program stored in ROM 311, for example. The operation unit 316 is an input device that receives an instruction input by the user of the mobile phone 300, and is, for example, various operation keys or buttons.

The ROM 311 is a ROM capable of writing and erasing such as an EPROM (Erasable Programmable ROM) and a flash memory, and stores data in a nonvolatile manner. The RAM 312 volatilely stores data generated by execution of a program by the CPU 310 or data input via the operation unit 316.

The camera 313 captures a subject in accordance with the operation of the operation unit 316 by the user. The image data of the photographed subject is stored in the RAM 312 or an external memory (for example, a memory card).

The microphone 314 receives user's voice input. The mobile phone 300 digitizes the input audio signal as analog data. Then, the cellular phone 300 sends an audio signal as a digitized signal to a communication target (for example, another cellular phone). The speaker 315 outputs an audio signal as an analog signal based on, for example, music data stored in the RAM 312.

The display panel 318 displays images stored in the ROM 311 and the RAM 312 by the display control circuit 309. The display panel 318 may be overlaid on the touch panel 120 or may incorporate the touch panel 120. Note that the touch recognition signal indicating the touch position on the touch panel 120 generated by the touch panel controller 110 may have the same role as the signal indicating that the operation unit 316 is operated.

The touch panel system 100 includes a touch panel controller 110 and a touch panel 120. The operation of the touch panel system 100 is controlled by the CPU 310.

Note that the process of determining the capacitance estimation value based on the digitized linear sum signal may be executed by the CPU 310 provided outside the touch panel controller 110.

That is, the signal processing units 114a and 114b, the inner product calculation units 115a and 115b, and the estimated value evaluation units 116a and 116b included in the touch panel controller 110 in the first embodiment may be provided in the CPU 310.

In this case, the touch panel controller 110 provides the digitized linear sum signal from the AD conversion units 113a and 113b to the signal processing units 114a and 114b provided in the CPU 310.

The CPU 310 performs the same processing as that in the first embodiment in each of the signal processing units 114a and 114b, the inner product calculation units 115a and 115b, and the estimated value evaluation units 116a and 116b.

The mobile phone 300 according to the present embodiment includes the touch panel system 100, so that the capacitance can be accurately estimated. Therefore, the mobile phone 300 can accurately recognize an input operation performed on the touch panel system 100 by the user. Therefore, the mobile phone 300 can accurately execute the process desired by the user.

In the present embodiment, the mobile phone 300 as an example of an electronic device including the touch panel system 100 is a mobile phone with a camera or a smartphone, but the electronic device including the touch panel system 100 is not limited thereto. For example, a mobile terminal device such as a tablet and an information processing device such as a PC monitor, signage, an electronic blackboard, and an information display are also included in the electronic device provided with the touch panel system 100.

[Embodiment 3]
The control block (particularly the CPU 310) of the mobile phone 300 may be realized by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or may be realized by software using a CPU.

In the latter case, the mobile phone 300 includes a CPU that executes instructions of a program that is software that realizes each function, a ROM or a storage device in which the above-described program and various data are recorded so as to be readable by a computer (or CPU). (Referred to as “recording medium”), and a RAM or the like for expanding the program. And the objective of this invention is achieved when a computer (or CPU) reads the said program from the said recording medium and runs it. As the recording medium, a “non-temporary tangible medium” such as a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. The program may be supplied to the computer via an arbitrary transmission medium (such as a communication network or a broadcast wave) that can transmit the program. The present invention can also be realized in the form of a data signal embedded in a carrier wave in which the program is embodied by electronic transmission.

[Summary]
The touch panel controller (110) according to the first aspect of the present invention drives M (M is an integer of 2 or more) drive lines (DL1 to DLM) N times based on a code sequence having a sequence length N (N is an integer). By doing so, N pieces of M capacitances (eg, C1, 1 to C1, M) formed at the intersections of the M drive lines and one sense line (eg, SL1), respectively. A drive unit (111) for outputting a linear sum signal from the sense line, and holding the N number of linear sum signals, then K (K is an integer satisfying 0 <K <N). Sequentially updating the drive unit with the latest K linear sum signals obtained each time the drive line is driven K times, so that K updated linear sum signals and (NK) Linear sum signal before update A signal processing unit (114a, 114b) that outputs the output signals, and an inner product operation of the N output signals and the code sequence, thereby obtaining a static value as an estimated value of the M electrostatic capacitance values. And an inner product calculation unit (115a, 115b) for calculating an estimated electric capacity.

According to the above configuration, in the touch panel controller, the drive unit drives the M drive lines N times based on the code sequence of the sequence length N, whereby the intersection of the M drive lines and one sense line. N linear sum signals relating to the M electrostatic capacitances respectively formed in the sense line are output from the sense line.

The signal processing unit holds N linear sum signals output from the sense lines. After that, each time the driving unit drives the drive line K times and the latest K linear sum signals are output from the sense line, the signal processing unit, among the N linear sum signals already held, The K linear sum signals are sequentially updated with the latest K linear sum signals.

Then, the signal processing unit outputs N linear sum signals composed of K updated linear sum signals and (NK) pre-updated linear sum signals as N output signals. .

The inner product calculation unit performs an inner product calculation of the output signal and the code sequence, that is, an inner product calculation of N output signals and a code sequence of sequence length N between N-dimensional vectors, and M electrostatic An estimated capacitance value is calculated as an estimated value of the capacitance value. That is, the inner product calculation unit performs an inner product calculation using K updated linear sum signals, which are the latest linear sum signals included in the output signal.

On the other hand, according to the touch panel controller in the conventional touch panel system described in Patent Document 1, the inner product calculation is performed every time the drive unit drives the drive line N times. For this reason, if a temporary change in capacitance occurs during driving of the N drive lines, the error in the estimated capacitance value due to the temporary capacitance is so large that it cannot be ignored. There was a problem that could be.
According to the touch panel controller of one embodiment of the present invention, the inner product calculation is performed using the K updated linear sum signals. Therefore, when a temporary change in capacitance occurs during driving of the N drive lines, the degree of error in the estimated capacitance value caused by the temporary capacitance is conventionally determined. This can be further suppressed as compared with the touch panel controller.

Therefore, according to the touch panel controller according to one aspect of the present invention, the capacitance can be estimated more accurately.

In addition, the touch panel controller according to aspect 2 of the present invention is the estimated value evaluation unit (116a, 116b) that determines a representative value of the estimated capacitance value from the plurality of estimated capacitance values in the aspect 1. May be further provided.

According to the above configuration, the accuracy of the estimated capacitance value can be further improved by using the representative value of the estimated capacitance value determined by the estimated value evaluation unit as the estimated capacitance value.

In the touch panel controller according to aspect 3 of the present invention, in the aspect 2, the estimated value evaluation unit calculates the standard deviation of the plurality of estimated capacitance values, and the standard deviation is the minimum. The estimated capacitance value may be determined as a representative value of the estimated capacitance value.

According to the above configuration, the estimated value evaluation unit determines the estimated capacitance value having the smallest standard deviation, and thus can obtain a highly accurate estimated capacitance value in which the influence of the error is suppressed. it can.

In the touch panel controller according to aspect 4 of the present invention, in the aspect 2, the estimated value evaluation unit calculates a variance of the plurality of estimated capacitance values, and the capacitance estimation has a minimum variance. The value may be determined as a representative value of the estimated capacitance value.

According to the above configuration, since the estimated value evaluation unit determines the estimated capacitance value having the minimum variance, it is possible to obtain a highly accurate estimated capacitance value in which the influence of the error is suppressed. .

In the touch panel controller according to aspect 5 of the present invention, in the aspect 2, the estimated value evaluation unit calculates an average value of a plurality of the estimated capacitance values, and the average value is calculated as the estimated capacitance value. It may be determined as a representative value.

According to the above configuration, the estimated value evaluation unit determines the estimated capacitance value as the average value of the plurality of estimated capacitance values, and thus the highly accurate capacitance with the influence of the error suppressed. An estimate can be obtained.

Also, in the touch panel controller according to aspect 6 of the present invention, in any one of the aspects 1 to 5, the code sequence may be generated based on an M-sequence code.

According to the above configuration, since the circuit for generating the code sequence based on the M-sequence code can be realized by a shift register or the like, the configuration of the circuit for generating the code sequence can be facilitated.

Also, in the touch panel controller according to aspect 7 of the present invention, in any one of the aspects 1 to 5, the code sequence may be generated based on a Walsh code or a Hadamard code.

According to the above configuration, a code sequence in which the correlation between codes is 0 is generated based on the Walsh code or Hadamard code. Therefore, the error due to the signal of another drive line is not included in the signal of each drive line, and the accuracy of various calculations in the touch panel controller can be further improved.

Further, the touch panel controller according to aspect 8 of the present invention may be set such that the value of K is 0 <K <N / 2 in any one of the above aspects 1 to 7.

According to the above configuration, a situation in which a part of the updated linear sum signal is further updated in the next update in the output signal is avoided, so that the inner product calculation in the inner product calculation unit can be performed effectively. it can.

Further, the integrated circuit according to aspect 9 of the present invention may include the touch panel controller according to any one of aspects 1 to 8.

A touch panel system according to aspect 10 of the present invention includes a touch panel controller according to any one of aspects 1 to 8, M (M is an integer of 2 or more) drive lines, and P (P is 1 or more). And a touch panel having sense lines.

Moreover, the electronic device according to aspect 11 of the present invention may include the touch panel system according to aspect 10 described above.

In addition, the electronic device according to the eleventh aspect may be realized by a computer. In this case, the electronic device is realized by the computer by causing the computer to operate as each unit included in the electronic device. A program and a computer-readable recording medium on which the program is recorded also fall within the scope of the present invention.

[Additional Notes]
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention. Furthermore, a new technical feature can be formed by combining the technical means disclosed in each embodiment.

The present invention can also be expressed as follows.

That is, the touch panel controller according to one embodiment of the present invention includes N capacitances formed between M drive lines (M is an integer of 2 or more) and one sense line. The touch panel controller includes a drive unit that is driven in parallel with a plurality of M-dimensional vectors (N is an integer), and that outputs N linear sum signals based on the charges accumulated in the M capacitances from the sense line. And an inner product calculation unit for estimating the value of the M electrostatic capacitances by calculating the inner product of the first linear sum signal and M N-dimensional vectors, each time the drive line is driven K times. (K is an integer, and 0 <K <N), a new linear sum signal in which a part of the value of the linear sum signal is different is obtained, and the inner product of the new linear sum signal and M N-dimensional vectors The M electrostatic capacitances are calculated. To estimate the value.

In addition, the touch panel controller according to an aspect of the present invention selects and outputs an estimated value with few errors among a plurality of estimated capacitance values obtained every time the drive line is driven K times.

Further, the touch panel controller according to an aspect of the present invention selects the signal with less error based on the standard deviation of the capacity estimation value.

Further, the touch panel controller according to one embodiment of the present invention outputs an average value of a plurality of capacitances obtained every time K is driven.

The touch panel device according to one embodiment of the present invention includes a touch panel controller and a touch panel controlled by the touch panel controller.

Moreover, an electronic device according to one embodiment of the present invention includes a touch panel controller and a touch panel controlled by the touch panel controller.

The present invention can be used for a touch panel controller, an integrated circuit including the touch panel controller, a touch panel system, and an electronic device.

100, 100s Touch panel system 110, 110s Touch panel controller 111, 111s Drive unit 114a, 114b, 114s Signal processing unit 115a, 115b, 115s Inner product calculation unit 116a, 116b, 116s Estimated value evaluation unit 120, 120s Touch panel 300 Mobile phone (electronic device) )
M integer (an integer representing the number of drive lines)
N integer (an integer representing the code length of the code sequence)
K integer (an integer representing the interval at which the linear sum signal should be updated)

Claims (5)

1. Based on a code sequence having a sequence length N (N is an integer), the drive line of M (M is an integer of 2 or more) is driven N times so that the intersection of the M drive lines and one sense line. A driving unit that outputs N linear sum signals relating to M capacitances respectively formed from the sense line;
   After holding the N linear sum signals, K linear sum signals are obtained each time the driving unit drives the drive line K times (K is an integer satisfying 0 <K <N). By sequentially updating with K linear sum signals, N output signals consisting of K updated linear sum signals and (NK) pre-update linear sum signals are output. A signal processing unit to
   An inner product calculation unit that calculates an estimated capacitance value as an estimated value of the M capacitance values by performing an inner product calculation of the output signal and the code sequence. Touch panel controller.
2. The touch panel controller according to claim 1, further comprising an estimated value evaluation unit that determines a representative value of the estimated capacitance value from the plurality of estimated capacitance values.
3. The estimated value evaluation unit calculates a standard deviation of the plurality of estimated capacitance values,
   The touch panel controller according to claim 2, wherein the estimated capacitance value having the smallest standard deviation is determined as a representative value of the estimated capacitance value.
4. The touch panel controller according to any one of claims 1 to 3,
   A touch panel system comprising: M (M is an integer of 2 or more) drive lines and P (P is an integer of 1 or more) sense lines.
5. An electronic device comprising the touch panel system according to claim 4.

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