The present invention relates to a signal processing system that estimates a value of a linear element or an input of the linear element by performing addition-subtraction-based signal processing on a plurality of time-series signals time-discretely sampled based on the linear element, a touch panel system including a touch panel that includes a plurality of capacitors disposed at respective intersection points of a plurality of drive lines and a plurality of sense lines and a touch panel controller that controls the touch panel, and an electronic device.
The inventors have proposed a touch panel controller that controls a touch panel including a plurality of capacitors disposed at respective intersection points of a plurality of drive lines and a plurality of sense lines and estimates or detects capacitances accumulated in the respective capacitors arranged in a matrix form (PTL 1).
This touch panel controller performs parallel driving on the plurality of drive lines on the basis of a code sequence to time-discretely sample and read along the respective sense lines linear-sum signals based on electric charge accumulated in the capacitors and estimates or detects capacitances of the capacitors by computing an inner product of the read linear-sum signals and the code sequence.
PTL 1: Japanese Patent “No. 5231605 (registered on Mar. 29, 2013)”
With the related art described above, however, noise mixes into the time-discretely sampled linear-sum signals, making estimation or detection of capacitances of the capacitors inaccurate. This consequently makes it difficult for the touch panel controller to operate favorably.
It is an object of the present invention to reduce noise mixing into an estimated result of a value or input of a linear element by performing addition-subtraction-based signal processing on the basis of input/output transfer characteristics and a frequency and an amount of noise mixing into a plurality of time-series signals time-discretely sampled based on the linear element.
To this end, a signal processing system according to an aspect of the present invention is a signal processing system that estimates a value of a linear element or an input of the linear element by performing addition-subtraction-based signal processing on a plurality of time-series signals time-discretely sampled based on the linear element. The signal processing system includes a first sub-system and a second sub-system having different input/output transfer characteristics, and a switch circuit that switches between the first sub-system and the second sub-system and connects one of the first sub-system and the second sub-system to the linear element, based on a frequency and an amount of noise mixing into the time-series signals and the input/output transfer characteristics so as to reduce noise mixing into an estimated result of the value or input of the linear element. The first sub-system performs frame-by-frame driving in which first frame driving to (M+1)-th frame driving are performed, in each of which first vector driving to (N+1)-th vector driving each including even-numbered phase driving and odd-numbered phase driving are performed in this order (where N and M are integers). The second sub-system performs plurality-of-vector continuous driving in which k-th vector driving to (k+j)-th vector driving (where k and j are integers that satisfy 1≦k≦N and 1≦j≦N−1, respectively) of each frame driving are performed in this order.
To this end, a touch panel system according to an aspect of the present invention is a touch panel system including a touch panel including a plurality of capacitors disposed at respective intersection points of a plurality of drive lines and a plurality of sense lines, and a touch panel controller that controls the touch panel. The touch panel controller includes a drive circuit that drives the capacitors along the drive lines, amplification circuits that read along the respective sense lines and amplify a plurality of linear-sum signals based on respective capacitors driven by the drive circuit, an analog-digital conversion circuit that performs analog-digital conversion on outputs of the amplification circuits, a decoding computation circuit that estimates capacitances of electric charge accumulated in the capacitors on the basis of the analog-digital-converted outputs of the amplification circuits, a first sub-system and a second sub-system having different input/output transfer characteristics, and a switch circuit that switches between the first sub-system and the second sub-system and connects one of the first sub-system and the second sub-system to the linear elements. The first sub-system performs frame-by-frame driving in which first frame driving to (M+1)-th frame driving are performed, in each of which first vector driving to (N+1)-th vector driving each including even-numbered phase driving and odd-numbered phase driving are performed in this order (where N and M are integers). The second sub-system performs plurality-of-vector continuous driving in which k-th vector driving to (k+j)-th vector driving (where k and j are integers that satisfy 1≦k≦N and 1≦j≦N−1, respectively) of each frame driving are performed in this order.
To this end, an electronic device according to an aspect of the present invention includes the touch panel system according to the present invention and a display device compatible with the touch panel system.
According to an aspect of the present invention, an advantageous effect is obtained which successfully reduces noise mixing into an estimated result of a value or input of a linear element by performing addition-subtraction-based signal processing on the basis of input/output transfer characteristics and a frequency and an amount of noise mixing into a plurality of time-series signals time-discretely sampled based on the linear element.
Embodiments of the present invention will be described in detail below.
The control circuit 14 includes sub-systems 5a and 5b having input/output transfer characteristics different from each other and a switch circuit 6 that connects one of the sub-systems 5a and 5b to the drive circuit 4.
Each of the linear elements CX is driven by the drive circuit 4, which is controlled by the sub-system 5a or 5b, and supplies an analog interface 7a (e.g., an amplification circuit) with a time-series signal having a value that can be observed continuously or discretely and that changes instantly. The analog interface 7a amplifies this time-series signal and outputs the amplified time-series signal to an AD conversion circuit 13. The AD conversion circuit 13 performs AD conversion on the time-series signal supplied from the analog interface 7a, and supplies a linear element estimation unit 11 with a plurality of time-series signals that are time-discretely sampled and that change instantly. The linear element estimation unit 11 performs addition-subtraction-based signal processing on the plurality of AD-converted time-series signals based on the linear element CX and estimates a value of the linear element CX or an input of the linear element CX. The signal processing system 10 includes an amount-of-noise estimation circuit 9 that estimates an amount of noise that mixes into the time-series signals, from the estimated value of the linear element CX or the estimated input value of the linear element CX obtained by the linear element estimation unit 11.
The switch circuit 6 switches between the sub-systems 5a and 5b and connects one of the sub-systems 5a and 5b to the drive circuit 4, based on input/output transfer characteristics and a frequency and an amount of noise mixing into the time-series signals so as to reduce noise mixing into the estimated result of the value or input of the linear element CX by performing addition-subtraction-based signal processing.
The control circuit 14 controls the analog interface circuit 7a. For example, the control circuit 14 controls a signal for even-numbered phase driving and odd-numbered phase driving between which the input state to the amplifier circuit is switched. The control circuit 14 also controls the sampling frequency and the number of multiple sampling used by the AD conversion circuit 13. The control circuit 14 further controls an operation of the linear element estimation unit 11.
The number of multiple sampling of the time-series signals from the linear element CX based on the sub-system 5a can be different from the number of multiple sampling of the time-series signals from the linear element CX based on the sub-system 5b. The sampling frequency of the time-series signals from the linear element CX based on the sub-system 5a can be different from the sampling frequency of the time-series signals from the linear element CX based on the sub-system 5b.
The positive/negative sign of the plurality of time-series signals based on the sub-systems 5a and 5b can invert with time. In addition, the positive/negative sign of the plurality of time-series signals based on the sub-systems 5a and 5b can be constant with time.
The switch circuit 6 switches between the sub-systems 5a and 5b on the basis of the estimated result obtained by the amount-of-noise estimation circuit 9.
The linear element CX can be, for example, a capacitor. The linear element CX may be a thermometer including a thermocouple. In this case, the signal processing system 10 can work even without the drive circuit 4. A configuration capable of reducing noise by amplifying, using an amplification circuit, a weak voltage (weak current) that can be observed with a thermocouple and then performing sampling using the AD conversion circuit 13 while changing the number of samples in multiple sampling and the sampling frequency can be implemented.
(Amount of Noise and Frequency Characteristics Between Sampling Frequency and Amount of Amplitude Change)
A characteristic C1 indicates a frequency characteristic of double sampling in which two signals are sampled and a simple moving average thereof is output. A characteristic C2 indicates a frequency characteristic of quadruple sampling in which four signals are sampled and a simple moving average thereof is output. A characteristic C3 indicates a frequency characteristic of octuple sampling in which eight signals are sampled and a simple moving average thereof is output. A characteristic C4 indicates a frequency characteristic of 16-tuple sampling in which 16 signals are sampled and a simple moving average thereof is output.
According to this graph of the frequency characteristic, as for double sampling, an amount of amplitude change is −∞ dB when the normalization coefficient is 0.5 as indicated by the characteristic C1. Accordingly, noise is successfully removed if the sampling frequency is set to be twice as high as the noise frequency. In addition, noise is successfully reduced if the sampling frequency is changed to make the normalized frequency close to 0.5.
As for quadruple sampling, an amount of amplitude change is −∞ dB when the normalization coefficient is 0.5 and 0.25 as indicated by the characteristic C2. Accordingly, noise is successfully removed if the sampling frequency is set to be twice or four times as high as the noise frequency. In addition, noise is successfully reduced if the sampling frequency is changed to make the normalized frequency close to 0.5 or 0.25.
As for octuple sampling, an amount of amplitude change is −∞ dB when the normalization coefficient is 0.5, 0.375, 0.25, and 0.125 as indicated by the characteristic C3. Accordingly, noise is successfully removed if the sampling frequency is set to be twice, 2.67 times, four times, or eight times as high as the noise frequency. In addition, noise is successfully reduced if the sampling frequency is changed to make the normalized frequency close to 0.5, 0.375, 0.25 or 0.125.
As for 16-tuple sampling, noise is successfully removed or reduced by setting or changing the sampling frequency as indicated by the characteristic C4, respectively.
As described above, noise is successfully removed or reduced by setting or changing the sampling frequency relative to the noise frequency.
For example, when the normalized frequency is 0.25, the amount of amplitude change is −3 dB for double sampling; whereas the amount of amplitude change is −∞ dB for quadruple sampling, octuple sampling, and 16-tuple sampling. Accordingly, if the number of multiple sampling is changed from double to any of quadruple, octuple, and 16-tuple, noise is successfully removed. In this way, noise is successfully removed or reduced also by changing the number of multiple sampling.
Therefore, the sampling frequency of the plurality of sub-systems illustrated in
(Configuration of Touch Panel System 1]
The touch panel controller 3 includes the drive circuit 4 that drives the capacitors C11 to C44 along the drive lines DL1 to DL4.
The touch panel controller 3 includes amplification circuits 7 each connected to a corresponding one of the sense lines SL1 to SL4. The amplification circuits 7 read a plurality of linear-sum signals based on capacitances accumulated in the respective capacitors C11 to C44 driven by the drive circuit 4 along the sense line SL1 to SL4 and amplify the plurality of linear-sum signals. The amplification circuits 7 each include an amplifier 18, and an integral capacitance Cint and a reset switch connected in parallel with the amplifier 18.
The touch panel controller 3 includes the AD conversion circuit 13 that performs analog-digital conversion on outputs of the amplification circuits 7 and a decoding computation circuit 8 that estimates a capacitance accumulated in each of the capacitors C11 to C44 on the basis of the analog-digital-converted outputs of the amplification circuits 7.
The touch panel controller 3 includes the control circuit 14 that controls the drive circuit 4. The control circuit 14 includes the sub-systems 5a and 5b having different input/output transfer characteristics and the switch circuit 6 that switches between the sub-systems 5a and 5b and connects one of the sub-systems 5a and 5b to the drive circuit 4 on the basis of a frequency and an amount of noise mixing into the linear-sum signals and the input/output transfer characteristics so as to reduce noise mixing into estimated results of the capacitances of the capacitors C11 to C44 obtained by the decoding computation circuit 8.
The control circuit 14 controls the sampling frequency and the number of multiple sampling used by the AD conversion circuit 13. Further, the control circuit 14 controls an operation of the decoding computation circuit 8.
The touch panel controller 3 also includes the amount-of-noise estimation circuit 9 that estimates an amount of noise mixing into the linear-sum signals, from estimated values of the capacitances obtained by addition-subtraction-based signal processing on the linear-sum signals. The switch circuit 6 switches between the sub-systems 5a and 5b on the basis of the estimation result obtained by the amount-of-noise estimation circuit 9.
(Operation of Touch Panel System 1)
The drive circuit 4 drives the drive lines DL1 to DL4 on the basis of a code sequence of 4 rows and 4 columns denoted by Expression 3 in
The amplification circuits 7 receive and amplify measured linear-sum values Y1, Y2, Y3, and Y4 along the sense lines of capacitances based on electric charge accumulated in capacitors driven by the drive circuit 4.
For example, during first driving among driving that is performed four times using the code sequence of 4 rows and 4 columns, the drive circuit 4 applies the voltage Vdrive to the drive line DL1 and applies zero volts to the other drive lines DL2 to DL4. Then, for example, the measured value Y1 from the sense line SL3, which corresponds to the capacitor C31 accumulating a capacitance C31 indicated by Expression 1 in
Then, during second driving, the drive circuit 4 applies the voltage Vdrive to the drive line DL2 and applies zero volts to the other drive lines DL1, DL3, and DL4. Then, the measured value Y2 from the sense line SL3, which corresponds to the capacitor C32 accumulating a capacitance C32 indicated by Expression 2 in
Then, during third driving, the drive circuit 4 applies the voltage Vdrive to the drive line DL3 and applies zero volts to the other drive lines. Then, during fourth driving, the drive circuit 4 applies the voltage Vdrive to the drive line DL4 and applies zero volts to the other drive lines.
As a result, the measured values Y1, Y2, Y3, and Y4 are associated with the capacitance values C1, C2, C4, and C4, respectively, as indicated by Expressions 3 and 4 in
(−C×Vdrive/Cint)+(Cp×Vn/Cint).
Accordingly, noise represented as
Ey=Cp×Vn/Cint
mixes into the linear-sum signal.
The drive circuit 4 drives the drive lines DL1 to DL4 on the basis of an orthogonal code sequence of 4 rows and 4 columns represented by Expression 5 in
Then, the capacitances C1 to C4 are successfully estimated as indicated by Expression 7 by determining an inner product of the measured values Y1, Y2, Y3, and Y4 and the orthogonal code sequence as indicated by Expression 6 in
Since noise is relatively large in the touch panel system, the above operation is sometimes performed a plurality of times and averaged linear-sum signal data is sometimes treated as a true value. The sub-systems 5a and 5b (see
(Configuration of Touch Panel System 1a)
The touch panel system 1a includes a touch panel controller 3a. The touch panel controller 3a includes a switch circuit 12. The switch circuit 12 switches the input state of each amplification circuit (sense amplifier) 7 between an even-numbered phase state (phase 0) in which a 2n-th sense line and a (2n+1)-th sense line are input and an odd-numbered phase state (phase 1) in which the (2n+1)-th sense line and a (2n+2)-th sense line are input. Here, n is an integer greater than or equal to zero and less than or equal to 31.
The control circuit 14 controls the amplification circuits 7. For example, the control circuit 14 controls a signal supplied to the switch circuit 12 and corresponding to even-numbered phase driving and odd-numbered phase driving between which the input state to the amplification circuits 7 is switched, for example. The control circuit 14 also controls the sampling frequency and the number of multiple sampling used in the AD conversion circuit 13. The control circuit 14 further controls an operation of the decoding computation circuit 8.
(Driving Methods by Touch Panel System 1a)
Parts (a), (b), (c), and (d) of
Part (a) of
The even-numbered phase driving Phase0 of the vector driving Vector0 included in the frame driving Flame0 to FlameM illustrated in part (a) of
Part (b) of
Then, the capacitors are driven by continuously performing only the phase driving Phase1 of the vector driving Vector0 included in the frame driving Flame0 to FlameM in an order of the phase driving Phase1 included in the vector driving Vector0 of the frame driving Flame0, the phase driving Phase1 included in the vector driving Vector0 of the frame driving Flame1, the phase driving Phase1 included in the vector driving Vector0 of the frame driving Flame2, . . . , and the phase driving Phase1 included in the vector driving Vector0 of the frame driving FlameM.
Then, the capacitors are driven by continuously performing only the phase driving Phase0 of the vector driving Vector1 included in the frame driving Flame0 to FlameM in an order of the phase driving Phase0 included in the vector driving Vector1 of the frame driving Flame0, the phase driving Phase0 included in the vector driving Vector1 of the frame driving Flame1, the phase driving Phase0 included in the vector driving Vector1 of the frame driving Flame2, . . . , and the phase driving Phase0 included in the vector driving Vector1 of the frame driving FlameM. Thereafter, driving is similarly performed up to the vector driving VectorN.
Part (c) of
Then, the capacitors are driven by continuously performing only the vector driving Vector1 included in the frame driving Flame0 to FlameM in an order of the vector driving Vector1 of the frame driving Flame0, the vector driving Vector1 of the frame driving Flame1, the vector driving Vector1 of the frame driving Flame2, . . . , and the vector driving Vector1 of the frame driving FlameM.
Then, the capacitors are driven by continuously performing only the vector driving Vector2 included in the frame driving Flame0 to FlameM in an order of the vector driving Vector2 of the frame driving Flame0, the vector driving Vector2 of the frame driving Flame1, the vector driving Vector2 of the frame driving Flame2, . . . , and the vector driving Vector2 of the frame driving FlameM. Thereafter, driving is similarly performed up to the vector driving VectorN.
Part (d) of
First, the capacitors are driven by continuously performing only the vector driving Vector0 to L included in the frame driving Flame0 to FlameM in an order of the vector driving Vector0 to L of the frame driving Flame0, the vector driving Vector0 to L of the frame driving Flame1, the vector driving Vector0 to L of the frame driving Flame2, . . . , and the vector driving Vector0 to L of the frame driving FlameM.
Then, the capacitors are driven by continuously performing only the vector driving VectorL+1 to 2L+1 included in the frame driving Flame0 to FlameM in an order of the vector driving VectorL+1 to 2L+1 of the frame driving Flame0, the vector driving VectorL+1 to 2L+1 of the frame driving Flame1, the vector driving VectorL+1 to 2L+1 of the frame driving Flame2, . . . , and the vector driving VectorL+1 to 2L+1 of the frame driving FlameM.
Then, the capacitors are driven by continuously performing only the vector driving Vector2L+2 to 3L+2 included in the frame driving Flame0 to FlameM in an order of the vector driving Vector2L+2 to 3L+2 of the frame driving Flame0, the vector driving Vector2L+2 to 3L+2 of the frame driving Flame1, the vector driving Vector2L+2 to 3L+2 of the frame driving Flame2, . . . , and the vector driving Vector3L+2 of the frame driving FlameM. Thereafter, driving is similarly continued up to the vector driving VectorN included in the frame driving FlameM.
If the number of consecutive vectors is not L+1 during driving in which the vector driving VectorN included in Flame0 to FlameM−1 appears, dummy driving may be performed as many times as the shortage or a blank period equivalent to the shortage may be provided.
In addition, in the case of L=0, the plurality-of-vector continuous driving is the same as the identical-vector continuous driving illustrated in part (c) of
Parts (a), (b), and (c) of
Part (a) of
Then, the phase driving Phase0 included in the vector driving Vector0 of the frame driving Flame2 is performed. Then, the phase driving Phase0 included in the vector driving Vector0 of the frame driving Flame3 is inversely performed.
Inversion in the phase continuous inverted driving is performed on a one-phase-driving basis. An acquisition period of identical data for an averaging process is a period corresponding to one phase driving. The polarity of this identical data inverts for even-numbered times.
Part (b) of
Inversion in the identical-vector continuous inverted driving is performed on a two-phase-driving basis. The acquisition period of identical data for the averaging process is a period corresponding to two phase driving. In the identical-vector continuous inverted driving, the polarity inverts for two phase driving of even-numbered times.
Part (c) of
Inversion in the plurality-of-vector continuous inverted driving is performed on a 2×(L+1)-phase-driving basis. The acquisition period of identical data for the averaging process is a period corresponding to 2×(L+1) phase driving. In the plurality-of-vector continuous inverted driving, the polarity inverts for (2×(L+1)) phase driving for even-numbered times.
Part (a) of
In the case of the identical-vector continuous driving in which the vector driving Vector0 (1st vector) is continuously performed as illustrated in part (c) of
In the case of phase continuous driving in which the phase driving Phase0 included in the vector driving Vector0 (1st vectors) is continuously performed as illustrated in part (b) of
Part (a) of
As illustrated in part (a) of
As illustrated in part (b) of
Part (a) of
Referring to part (b) of
The linear-sum signal based on the phase driving Phase0 of the vector driving Vector0 is acquired at intervals of one phase (period T3 from time t6 to time t10) in the example in part (a) of
Part (a) of
In the case of L=2 in the plurality-of-vector continuous driving illustrated in part (d) of
Parts (a) and (b) of
Part (a) of
Part (b) of
These graphs illustrated in
Part (a) of
Part (b) of
In the example illustrated in
Parts (a) and (b) of
In an operation mode of the frame-by-frame driving described in part (a) of
In an operation mode of the phase continuous driving described in part (b) of
In an operation mode of the identical-vector continuous driving described in part (c) of
In an operation mode of the plurality-of-vector continuous driving described in part (d) of
In an operation mode of the phase continuous inverted driving in which phase driving is continuously performed while inverting even-numbered driving described in part (a) of
In an operation mode of the identical-vector continuous inverted driving in which vector driving is continuously performed while inverting the even-numbered driving described in part (b) of
In an operation mode of the plurality-of-vector continuous inverted driving in which vector driving is continuously performed while inverting even-numbered driving described in part (c) of
(Operation of Amount-of-Noise Estimation Circuit 9)
The amount-of-noise estimation circuit 9 makes a determination using a plurality of outputs of the linear element estimation unit (plurality of estimation results of values of the linear elements CX or inputs of the linear elements CX obtained by addition-subtraction-based signal processing). The switch circuit 6 switches between the sub-systems 5a and 5b on the basis of an estimation result obtained by the amount-of-noise estimation circuit 9. The plurality of estimated values are supposed to be the same value. When the plurality of estimated values are not the same value, the amount-of-noise estimation circuit 9 estimates that the influence of the amount of noise mixing into the estimated results has increased.
(Configuration of Sub-Systems)
The plurality of sub-systems included in the control circuit 14 can be configured into various types based on the above description in order to reduce external noise.
For example, a sub-system for which a unit in which a plurality of linear-sum signals based on the identical-phase driving of the identical-vector driving are added and average is set to a unit of a frame, a sub-system for which the addition-averaging unit is set to a unit of a phase, a sub-system for which the addition-averaging unit is set to a unit of a vector, and a sub-system for which the addition-averaging unit is set to a unit of a plurality of vectors may be provided, and any of these sub-systems may be selected so as to reduce external noise on the basis of the frequency characteristic between the normalized frequency and the rate of amplitude change.
In the case where this addition-averaging unit is a unit of a phase, a unit of a vector, and a unit of a plurality of vectors, a sub-system having a function for inverting the sign of the drive signal may be provided. In this case, sub-systems for which the driving inversion period is a unit of N phases (N is an integer) may be provided, and any of these sub-systems may be selected to reduce external noise based on the frequency characteristic.
Also, in the case where the drive-signal driving inversion function is provided, a sub-system that reduces the reset period of the reset signal that resets the amplification circuits may be provided.
Another embodiment of the present invention will be described based on
If the amplification circuits each include a differential amplifier in this manner, noise robustness of the touch panel controller can be further enhanced.
The CPU 96 controls an operation of the mobile phone 90. The CPU 96 executes a program stored in the ROM 98, for example. The operation keys 91 accept an instruction input by a user of the mobile phone 90. The RAM 97 volatilely stores data generated as a result of execution of the program by the CPU 96 or data input via the operation keys 91. The ROM 98 non-volatilely stores data.
The ROM 98 is a writable and erasable ROM, such as an EPROM (Erasable Programmable Read-Only Memory) or a flash memory. Although not illustrated in
The camera 95 captures an image of a subject in response to a user operation on one of the operation keys 91. Image data of a captured image of the subject is stored in the RAM 97 or an external memory (e.g., a memory card). The microphone 94 accepts input of user's voice. The mobile phone 90 digitizes the input voice (analog data). The mobile phone 90 then sends the digitized voice to a computation counterpart (e.g., another mobile phone). The speaker 93 outputs sound based on music data stored in the RAM 97, for example.
The touch panel system 1 includes the touch panel 2 and the touch panel controller 3. The CPU 96 controls an operation of the touch panel system 1. The CPU 96 executes a program stored in the ROM 98, for example. The RAM 97 volatilely stores data generated as a result of execution of the program by the CPU 96. The ROM 98 non-volatilely stores data.
The display panel 92b displays an image stored in the ROM 98 or the RAM 97 in accordance with the display control circuit 92a. The display panel 92b is disposed on the touch panel 2 or included in the touch panel 2.
The signal processing system 10 according to a first aspect of the present invention is a signal processing system that estimates a value of the linear element CX or an input of the linear element CX by performing addition-subtraction-based signal processing on a plurality of time-series signals time-discretely sampled based on the linear element CX and includes the sub-systems 5a and 5b having different input/output transfer characteristics, and the switch circuit 6 that switches between the sub-systems 5a and 5b and connects one of the sub-systems 5a and 5b to the linear element CX, based on a frequency and an amount of noise mixing into the time-series signals and the input/output transfer characteristics so as to reduce noise mixing into an estimated result of the value or input of the linear element CX. The sub-system 5a performs frame-by-frame driving in which frame driving Flame0 to frame driving FlameM are performed, in each of which vector driving Vector0 to vector driving VectorN each including even-numbered phase driving Phase0 and odd-numbered phase driving Phase1 are performed in this order (where N and M are integers). The 2 sub-system 5b performs plurality-of-vector continuous driving in which vector driving Vector(k) to vector driving Vector(k+j) of each of the frame driving Flame0 to FlameM (where k and j are integers that satisfy 1≦k≦N and 1≦j≦N−1, respectively) are performed in this order.
According to the above configuration, the sampling frequency and the number of multiple sampling for the time-series signals differ between the plurality-of-vector continuous driving and the frame-by-frame driving. Thus, by selecting one of the plurality-of-vector continuous driving and the frame-by-frame driving on the basis of a frequency characteristic between an amount of amplitude change of the time-series signals and a normalization coefficient, which is a ratio between the frequency of the time-series signals and the sampling frequency, noise mixing into an estimated result of the value or input of the linear element is successfully reduced by performing addition-subtraction-based signal processing based on a frequency and an amount of noise mixing into the plurality of time-series signals time-discretely sampled based on the linear element and the input/output transfer characteristics.
The signal processing system according to a second aspect of the present invention, in the first aspect, further includes a sub-system having an input/output transfer characteristic different from those of the sub-systems 5a and 5b. The sub-system may perform either identical-vector continuous driving in which k-th vector driving (where 1≦k≦N+1) of each frame driving is continuously performed or phase continuous driving in which even-numbered phase driving included in each k-th vector driving (where 1≦k≦N+1) of each frame driving is continuously performed and then odd-numbered phase driving included in each k-th vector driving is continuously performed.
According to the above configuration, the sampling frequency and the number of multiple sampling for the time-series signals in the identical-vector continuous driving and the phase continuous driving differ from those of the plurality-of-vector continuous driving and the frame-by-frame driving. Thus, by selecting one of the identical-vector continuous driving, the phase continuous driving, the plurality-of-vector continuous driving, and the frame-by-frame driving on the basis of a frequency characteristic between an amount of amplitude change of the time-series signals and a normalization coefficient, which is a ratio between the frequency of the time-series signals and the sampling frequency, noise mixing into an estimated result of the value or input of the linear element is successfully reduce by performing addition-subtraction-based signal processing based on a frequency and an amount of noise mixing into the plurality of time-series signals time-discretely sampled based on the linear element and the input/output transfer characteristics.
The signal processing system according to a third aspect of the invention, in the first aspect, further includes a third sub-system having an input/output transfer characteristic different from those of the first sub-system and the second sub-system. The third sub-system may perform any of phase continuous inverted driving, in which even-numbered phase driving included in each k-th vector driving (where 1≦k≦N+1) of each frame driving is continuously performed such that a positive/negative sign of the plurality of time-series signals inverts with time for each even-numbered phase driving and then odd-numbered phase driving included in each k-th vector driving is continuously performed such that the positive/negative sign of the plurality of time-series signals inverts with time for each odd-numbered phase driving; identical-vector continuous inverted driving, in which the k-th vector driving (where 1≦k≦N+1) of each frame driving is continuously performed such that the positive/negative sign of the plurality of time-series signals inverts with time for each vector driving; and plurality-of-vector continuous inverted driving, in which the k-th vector driving to (k+j)-th vector driving of each frame driving are performed in this order such that the positive/negative sign of the plurality of time-series signals inverts with time for each set of the k-th vector driving to the (k+j)-th vector driving.
According to the above configuration, the sampling frequency and the number of multiple sampling for the time-series signals in the phase continuous inverted driving, the identical-vector continuous inverted driving, and the plurality-of-vector continuous inverted driving differ from those of the plurality-of-vector continuous driving and the frame-by-frame driving. Thus, by selecting one of the phase continuous inverted driving, the identical-vector continuous inverted driving, and the plurality-of-vector continuous inverted driving on the basis of a frequency characteristic between an amount of amplitude change of the time-series signals and a normalization coefficient, which is a ratio between the frequency of the time-series signals and the sampling frequency, noise mixing into an estimated result of the value or input of the linear element is successfully reduced by performing addition-subtraction-based signal processing based on a frequency and an amount of noise mixing into the plurality of time-series signals time-discretely sampled based on the linear element and the input/output transfer characteristics.
In the signal processing system according to a fourth aspect of the present invention, in the first aspect, the switch circuit 6 may determine and change the number of multiple sampling and the sampling frequency of the time-series signals obtained from the linear element CX.
According to the above configuration, it is possible to switch the sub-system to a sub-system capable of reducing noise on the basis of a frequency characteristic between an amount of amplitude change of the time-series signals and a normalization coefficient, which is a ratio between the frequency of the time-series signals and the sampling frequency.
The signal processing system according to a fifth aspect of the present invention, in the first aspect, the switch circuit 6 may select to cause the positive/negative sign of the plurality of time-series signals to invert with time or keep the positive/negative sign constant with time.
According to the above configuration, the sampling frequency and the number of multiple sampling for the time-series signals differ depending on the presence/absence of inversion of the positive/negative sign. Thus, noise is successfully reduced by selecting a driving method on the basis of a frequency characteristic between an amount of amplitude change of the time-series signals and a normalization coefficient, which is a ratio between the frequency of the time-series signals and the sampling frequency.
The signal processing system according to a sixth aspect of the present invention, in the first aspect, further includes the amount-of-noise estimation circuit 9 that estimates the amount of noise from the estimated value of the linear element CX or the estimated value of the input of the linear element CX obtained by addition-subtraction-based signal processing on the time-series signals, and the switch circuit 6 may switch between the sub-systems 5a and 5b on the basis of an estimation result obtained by the amount-of-noise estimation circuit 9 to select whether the positive/negative sign of the plurality of time-series signals inverts with time or is constant with time and to determine and change the number of multiple sampling and the sampling frequency of the time-series signals from the linear element CX.
According to the above configuration, noise is successfully reduced by making selection, determination, and change based on a frequency characteristic between an amount of amplitude change of the time-series signals and a normalization coefficient, which is a ratio between the frequency of the time-series signals and the sampling frequency.
The signal processing system according to a seventh aspect of the present invention, in the first aspect, may further include the analog-digital conversion circuit 13 that performs analog-digital conversion on a plurality of time-series signals based on the linear element CX and generates the plurality of time-series signals time-discretely sampled.
According to the above configuration, the value of the linear element CX or input of the linear element CX is successfully estimated by digital signal processing.
A touch panel system according to an eighth aspect of the present invention is the touch panel system 1a including the touch panel 2 including a plurality of capacitors disposed at respective intersection points of a plurality of drive lines and a plurality of sense lines, and the touch panel controller 3a that controls the touch panel 2. The touch panel controller 3a includes the drive circuit 4 that drives the capacitors along the drive lines, the amplification circuits 7 that read along the sense lines and amplify a plurality of linear-sum signals based on the capacitors driven by the drive circuit 4, the analog-digital conversion circuit 13 that performs analog-digital conversion on outputs of the amplification circuits 7, the decoding computation circuit 8 that estimates capacitances of electric charge accumulated in the capacitors on the basis of the analog-digital-converted outputs of the amplification circuits 7, the sub-systems 5a and 5b having different input/output transfer characteristics, and the switch circuit 6 that switches between the sub-systems 5a and 5b and connects one of the sub-systems 5a and 5b to the linear element CX. The sub-system 5a performs frame-by-frame driving in which frame driving Flame0 to frame driving FlameM are performed, in each of which vector driving Vector0 to vector driving VectorN each including even-numbered phase driving Phase0 and odd-numbered phase driving Phase1 are performed in this order (where N and M are integers). The second sub-system performs plurality-of-vector continuous driving in which vector driving Vector(k) to vector driving Vector(k+j) (where, k and j are integers that satisfy 1≦k≦N and 1≦j≦N−1, respectively) of each of the frame driving Flame0 to FlameM are performed in this order.
In the touch panel system according to a ninth aspect of the present invention, in the eighth aspect, the amplification circuit 7a may include the differential amplifier 18a that differentially amplifies linear-sum signals output along adjacent sense lines.
According to the above configuration, noise robustness of the touch panel controller is successfully enhanced further.
An electronic device according to a tenth aspect of the present invention includes the touch panel system according to the eighth or ninth aspect of the present invention and the display unit 92 compatible with the touch panel system.
The present invention is not limited to each of the above-described embodiments, and various alterations can occur within the scope recited in the claims. An embodiment obtained by appropriately combining the technical means disclosed in the different embodiments is also within the technical scope of the present invention. Further, a new technical feature can be formed by combining the technical means disclosed in the individual embodiments.
The present invention can be utilized in a signal processing system that estimates a value of a linear element or an input of the linear element by performing addition-subtraction-based signal processing on a plurality of time-series signals time-discretely sampled based on the linear element, a touch panel system that includes a touch panel including a plurality of capacitors disposed at respective intersection points of a plurality of drive lines and a plurality of sense lines and a touch panel controller that controls the touch panel, and an electronic device.
Number | Date | Country | Kind |
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2014-049385 | Mar 2014 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2015/057207 | 3/11/2015 | WO | 00 |