JP2012234473A - Touch detection device and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a touch detection device capable of accurately adjusting a variation in detection data for each intersection capacitance of a touch sensor panel.SOLUTION: A touch sensor panel controller is provided with: a calibration circuit (304) that performs offset adjustment of input signals of plural detection circuits (301) corresponding to plural X electrodes of a touch sensor panel; and a memory (307) that stores adjustment parameters of the calibration circuit.

Description

  The present invention relates to a touch detection device and a semiconductor device applied to the touch detection device, and more particularly to a technique for adjusting an offset of a detection target capacitance of a touch sensor panel, for example, touch sense of a PDA (Personal Digital Assistant) or a tablet PC (Personal Computer). The present invention relates to a technology that is effective when applied to an input system or the like.

  The touch sensor panel corresponding to the multi-point touch by the mutual capacitance method is arranged so that, for example, the Y electrode as the drive electrode and the X electrode as the detection electrode are orthogonally crossing each other with a dielectric interposed therebetween, and the cross coupling of the respective intersections The intersection capacitance as the capacitance constitutes the intersection capacitance. When there is a finger or hand capacitance in the vicinity of the intersection capacitance, the mutual capacitance of the node decreases by the combined capacitance of the finger or hand. In order to detect at which intersection capacitance the change in mutual capacitance occurs, the touch sensor panel controller performs pulse-by-pulse charging operation by sequentially driving the drive electrodes, and the change in the charge charge is detected by each detection electrode. The signal detected according to the change in the mutual capacitance of the intersection capacitances arranged in matrix is obtained by sequentially repeating the operation detected from (1). For example, Patent Document 1 discloses a controller that detects a signal by driving a touch sensor panel using such a mutual capacitance method. In Patent Document 1, the detection circuit for detecting the signal of the X electrode is configured by an integration circuit using an operational amplifier. In the integration circuit, charges defined by the product of the drive voltage of the Y electrode and the capacitance value of the intersection capacitance are sequentially accumulated according to the AC pulse drive. By the way, a parasitic capacitance component exists in the path from the intersection capacitance to the integration circuit, and the magnitude thereof varies depending on the position and layout of the X electrode. Such variations appear as variations in the amount of charge input to the detection circuit via the X electrode. Patent Document 1 discloses a configuration in which a signal for canceling an offset is given to the output of an integration circuit in order to correct the influence of such variation.

US Patent Publication No. 2009 / 0244014A1

  The inventor has studied a technique for canceling a state in which detection data detected on the entire surface of the touch sensor panel varies in a non-touch state. According to this, the usefulness of adjusting the offset corresponding to each intersection capacity was found. That is, offset cancellation by offset adjustment data can be performed in a one-to-one correspondence with touch detection data. However, Patent Document 1 does not have such attention.

  Further, when the output of the detection circuit is corrected as in Patent Document 1, the correction is performed after amplification by an amplifier, so that a large adjustment amount must be taken. As a result, the scale and element size of the circuit that performs offset correction increase.

  An object of the present invention is to provide a touch detection device that can adjust the variation in detection data with high accuracy for each intersection capacity of a touch sensor panel.

  Still another object of the present invention is to provide a semiconductor device suitable for adjusting the variation of detection data with high accuracy for each intersection capacitance of a touch sensor panel.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  The following is a brief description of an outline of typical inventions disclosed in the present application.

  That is, the touch sensor panel controller is provided with a calibration circuit for performing offset adjustment on input signals of a plurality of detection circuits corresponding to a plurality of X electrodes of the touch sensor panel, and adjustment parameters of the calibration circuit are set. A memory for storing was provided.

  The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

  That is, the variation in detection data can be adjusted with high accuracy for each intersection capacitance of the touch sensor panel.

FIG. 1 is an explanatory diagram showing the overall configuration of a display and input device to which the present invention is applied. FIG. 2 is an explanatory diagram illustrating the electrode configuration of the touch sensor panel. FIG. 3 is a circuit diagram showing an example of an integration circuit as an equivalent circuit and a detection circuit of the touch sensor panel. FIG. 4 is a waveform diagram showing an example of an input waveform to the Y electrodes Y1 to YM. FIG. 5 is a timing chart illustrating the input pulse voltage to the Y electrodes Y1 to YM and the timing of the detection operation by the integration circuit. FIG. 6 is an explanatory view showing a mounting example of the touch sensor panel. FIG. 7 is an explanatory diagram illustrating the target value of the output voltage of the integrating circuit and the data (detection data) of the AD conversion result corresponding thereto. FIG. 8 is a block diagram showing a specific example of the touch sensor panel. FIG. 9 is a flowchart illustrating the operation of the touch sensor panel controller. FIG. 10 shows calibration frame data C_Data [y1, x1] to C_data [yM.y] stored in the touch sensor panel and the calibration RAM. It is explanatory drawing which illustrates a response | compatibility with xN]. FIG. 11 is a timing chart illustrating the operation timing regarding the Y electrodes Y1 to Y3 in the detection operation of the touch sensor panel. FIG. 12 is a block diagram illustrating a configuration for controlling the current amount of the constant current source according to the adjustment parameter as an example of the calibration circuit. FIG. 13 is a block diagram illustrating a configuration for controlling a capacitive coupling voltage according to an adjustment parameter as an example of a calibration circuit. FIG. 14 is a schematic illustration according to a modification in which the calibration circuit is configured to perform offset adjustment on the output signal of the detection circuit, compared to the touch sensor panel controller of the first embodiment shown in FIG. FIG. FIG. 15 is an explanatory diagram illustrating a detection result expected in a non-touch state when adjustment by the calibration circuit is not performed in the first embodiment. FIG. 16 is an explanatory diagram illustrating a detection result expected in a non-touch state when adjustment by the calibration circuit is performed in the first embodiment. FIG. 17 is a block diagram illustrating a touch sensor panel controller according to an embodiment of the invention. FIG. 18 is a flowchart of the operation mainly showing calibration data update control by the microprocessor.

1. First, an outline of a typical embodiment of the invention disclosed in the present application will be described. Reference numerals in the drawings referred to in parentheses in the outline description of the representative embodiments merely exemplify what are included in the concept of the components to which the reference numerals are attached.

[1] <Built-in memory for storing offset adjustment parameters>
A touch detection device according to a representative embodiment of the present invention includes a touch sensor panel (1) in which a plurality of Y electrodes (Y1 to YM) and X electrodes (X1 to XN) are arranged in a matrix, and the touch sensor. The touch sensor panel controller (3 (3A)) that drives the Y electrode of the panel and measures the capacitance value of the intersection capacitance of the Y electrode and the X electrode via the X electrode, and is transferred from the touch sensor panel controller And a microprocessor (5) that performs coordinate calculation based on capacitance distribution data (S_Data [y1, x1] to S_Data [yM, xN]) for each intersection of the Y electrode and the X electrode. The touch sensor panel controller includes a plurality of detection circuits (301) corresponding to the plurality of X electrodes, and a calibration for performing offset adjustment on input signals of the detection circuits corresponding to the plurality of X electrodes. A circuit (304), a memory (307 (307A, 307B)) storing adjustment parameters for the calibration circuit, and a control for supplying the adjustment parameters from the memory to the calibration circuit each time the Y electrode to be driven is switched. Circuit (310 (310A)).

  According to this, since the adjustment parameter is supplied from the memory to the calibration circuit every time the Y electrode is switched, it is possible to adjust the variation in detection data for each intersection capacitance of the touch sensor panel. Further, the calibration circuit for performing the offset adjustment is disposed on the input side of the detection circuit, and it is only necessary to perform the offset adjustment on the input signal before amplification by the detection circuit, so that it is not necessary to take a large adjustment amount.

[2] <Adjustment parameters for each intersection>
In the touch detection device according to item 1, the adjustment parameter is data for each intersection of the Y electrode and the X electrode.

  According to this, it is possible to adjust the variation in the detection data using the detection parameter unique to each intersection capacity of the touch sensor panel.

[3] <Optimization parameter adjustment by command>
In the touch detection device according to item 1, the adjustment parameter is optimized according to a command input from the microprocessor.

  According to this, the adjustment parameter can be flexibly optimized through the software of the microprocessor.

[4] <Bus interface connected to microprocessor>
The touch detection device according to Item 1, further including a bus interface (311) for connecting the memory to the microprocessor.

  This facilitates the process of initializing the adjustment parameter in the memory and updating the adjustment parameter held in the memory.

[5] <Calibration circuit acquires adjustment parameters every time the Y electrode is switched>
In the touch detection device according to Item 4, the touch sensor panel controller includes a drive circuit (300) that supplies and drives a pulse signal to the plurality of Y electrodes in the order of electrode arrangement. The detection circuit detects a capacitance value of an intersection capacitance (Cxy) with the X electrode that intersects the Y electrode in units of driven Y electrodes. The calibration circuit inputs an adjustment parameter of a corresponding address from the memory every time the Y electrode to which the pulse signal is applied is switched.

  According to this, similarly to the switching of the Y electrodes driven in the electrode order, the adjustment parameters may be read from the memory in the address order and supplied to the calibration circuit.

[6] <Current control of constant current source according to adjustment parameter>
In the touch detection device according to item 1, the calibration circuit is a circuit that adjusts a current amount of a constant current source circuit (310_n) connected to each X electrode by a corresponding adjustment parameter.

  According to this, the offset can be easily adjusted by controlling the amount of current from the constant current source circuit with respect to the input of the detection circuit.

[7] <Control of capacitive coupling voltage according to adjustment parameter>
In the touch detection device according to item 1, the calibration circuit is a circuit that adjusts the capacitive coupling voltage applied to the capacitive element (311_n) connected to each X electrode by a corresponding adjustment parameter.

  According to this, the offset can be easily adjusted by controlling the capacitive coupling voltage with respect to the input node of the detection circuit.

[8] <Control of voltage addition / subtraction according to adjustment parameter>
The touch detection device according to another embodiment of the present invention is different from the touch detection device according to item 1 in that the calibration circuit performs offset adjustment on the output signal of the detection circuit. ,At this time,
The calibration circuit is a circuit that adjusts an addition / subtraction amount to be added / subtracted to / from an output signal of the detection circuit using a corresponding adjustment parameter.

  According to this, the offset can be easily adjusted by voltage addition / subtraction control with respect to the output of the detection circuit.

[9] <Memory capable of storing a plurality of adjustment parameters>
In the touch detection device according to item 1, the memory includes a plurality of storage areas (307A and 307B) for storing different sets of adjustment parameters. When the difference between the non-touch detection data and the expected value exceeds the allowable value, the microprocessor stores a new set of adjustment parameters in the memory instead of the adjustment parameter set currently used. Control to update the set of adjustment parameters to be performed.

  According to this, it becomes possible to easily cope with a decrease in detection accuracy caused by environmental fluctuations such as temperature and humidity.

[10] <Switching parameter set after determining validity of new adjustment parameter>
In the touch detection device according to item 9, the microprocessor that performs the update control calculates a new set of adjustment parameters and stores the memory in the memory while keeping the currently used adjustment parameter set valid. When the set of adjustment parameters stored in another storage area is valid, control is performed to switch the adjustment parameter set to be used to the new adjustment parameter set.

  According to this, when referring to a detection signal in the middle of calculation of a new adjustment parameter, in a case where reliability cannot be obtained in the calculation result by mixing not only non-touch but also a touch state in the signal generation environment, Adjustment parameters that are currently valid can be temporarily used to avoid a significant drop in touch detection accuracy.

[11] <Built-in memory for storing adjustment parameters>
A semiconductor device (3 (3A)) according to another embodiment of the present invention has a capacitance value of an intersection capacitance of the Y electrode and the X electrode of a touch sensor panel in which a plurality of Y electrodes and X electrodes are arranged in a matrix. It is a device that measures. The semiconductor device performs offset adjustment on a drive circuit (300) for driving the Y electrode in pulses, a plurality of detection circuits (301) corresponding to the plurality of X electrodes, and an input signal of the detection circuit. Calibration circuit (304), a memory (307 (307A, 307B)) for storing the calibration parameters of the calibration circuit, and the adjustment parameters from the memory to the calibration circuit each time the Y electrode to be driven is switched. A control circuit to be supplied.

  According to this, since the adjustment parameter is supplied from the memory to the calibration circuit every time the Y electrode is switched, it is possible to adjust the variation in detection data for each intersection capacitance of the touch sensor panel. Further, the calibration circuit for performing the offset adjustment is disposed on the input side of the detection circuit, and it is only necessary to perform the offset adjustment on the input signal before amplification by the detection circuit, so that it is not necessary to take a large adjustment amount.

[12] <Calibration circuit acquires adjustment parameter every time Y electrode is switched>
In the semiconductor device according to Item 11, the detection circuit detects a capacitance value of an intersection capacitance (Cxy) with the X electrode that intersects the Y electrode in units of driven Y electrodes. The calibration circuit inputs an adjustment parameter for a corresponding address from the memory every time the Y electrodes are driven in the order of electrode arrangement.

  According to this, similarly to the switching of the Y electrodes driven in the electrode order, the adjustment parameters may be read from the memory in the address order and supplied to the calibration circuit.

[13] <External bus bus interface connected to memory>
Item 12. The semiconductor device according to Item 12, further comprising a bus interface (311) for connecting the memory to the outside.

  This facilitates the process of initializing the adjustment parameter in the memory and updating the adjustment parameter held in the memory.

[14] <Update adjustment parameter>
In the semiconductor measure of item 13, the memory has a plurality of storage areas (307A, 307B) for storing different sets of adjustment parameters. A storage area storing a set of adjustment parameters to be used is designated from the outside via a bus interface.

  When setting or updating adjustment parameters from the outside, it can be used for convenience of memory access control.

[15] <Built-in microprocessor>
The semiconductor device of Item 12 further includes a microprocessor (5) that performs coordinate calculation based on capacitance distribution data of the intersection capacitance obtained based on the output of the detection circuit, and the microprocessor stores the memory in the memory. Stores adjustment parameters.

  This can contribute to speeding up of processing and downsizing of the semiconductor device.

[16] <Update adjustment parameter>
In the semiconductor device of item 15, the memory has a plurality of storage areas (307A, 307B) for storing different sets of adjustment parameters. When the difference between the non-touch detection data and the expected value exceeds the allowable value, the microprocessor stores a new set of adjustment parameters in the memory instead of the adjustment parameter set currently used. Control to update the set of adjustment parameters to be performed.

  According to this, it becomes possible to easily cope with a decrease in detection accuracy caused by environmental fluctuations such as temperature and humidity.

[17] <Update adjustment parameter by command>
In the semiconductor device of item 15, the memory has a plurality of storage areas for storing different sets of adjustment parameters. The microprocessor issues a command based on non-touch detection to store a new set of adjustment parameters in the memory instead of the currently used set of adjustment parameters, and to use the adjustment parameter next. Control to update the set.

  According to this, the adjustment parameter can be flexibly updated through the software of the microprocessor.

[18] <Switching parameter set after determining validity of new adjustment parameter>
In the semiconductor device according to Item 16, the microprocessor that performs the update control calculates a new set of adjustment parameters and keeps the memory stored in the memory while the adjustment parameter set currently in use remains valid. When the adjustment parameter set stored in another storage area and completed is valid, control is performed to switch the adjustment parameter set to be used to the new adjustment parameter set.

  According to this, when referring to a detection signal in the middle of calculation of a new adjustment parameter, when not only non-touch but also a touch state is mixed in the signal generation environment, the reliability of the calculation result cannot be obtained at all. Therefore, it is possible to avoid a significant drop in the touch detection system by temporarily using the adjustment parameters that are currently valid.

2. Details of Embodiments Embodiments will be further described in detail.

<< Embodiment 1 >>
FIG. 1 is an explanatory diagram showing the overall configuration of a display and input device to which the present invention is applied. The display and input device shown in FIG. 1 constitutes a part of a portable terminal such as a PDA or a tablet PC, and includes a touch sensor panel (TP) 1, a liquid crystal display panel (DSP) 2 as a display panel, and a touch sensor panel controller. (TPC) 3 and a liquid crystal driver (DSPD) 4 as a display driver.

  The touch sensor panel controller 3 drives the touch sensor panel 1 based on the control of the subsystem microprocessor (SMPU) 5 and sequentially acquires and accumulates signals from the intersection capacitance array. It returns to the microprocessor 5 for subsystems.

  The touch sensor panel 1 is configured using a transmissive (translucent) electrode or a dielectric film, and is disposed, for example, on the display surface of the liquid crystal display 2 in a bitmap display form. The host processor (HMPU) 6 generates display data, and the liquid crystal display driver 4 performs display control for displaying the display data received from the host processor 6 on the liquid crystal display 2.

  The microprocessor 5 for the subsystem performs a digital filter operation on the signal received from the touch sensor panel controller 3, and when a touch event occurs on the touch sensor panel 3 based on the signal from which noise has been removed. The coordinates are calculated and given to the host processor 6. For example, the host processor 6 analyzes the input from the touch sensor panel 1 from the relationship between the display screen given to the liquid crystal display driver 4 and the coordinate data given from the subsystem microprocessor 5.

FIG. 2 illustrates an electrode configuration of the touch sensor panel. The touch sensor panel 1 is configured such that a large number of Y electrodes Y1 to YM formed in the horizontal direction and a large number of X electrodes X1 to XN formed in the vertical direction are electrically insulated from each other. Each electrode is formed in a rectangular shape in the middle of its extending direction to constitute a capacitive electrode. An intersection capacitance (mutual capacitance) is formed between the capacitance electrode connected to the X electrode and the capacitance electrode connected to the Y electrode. The Y electrodes Y1 to YM are driven by applying pulses in the order of electrode arrangement .

  FIG. 3 shows an example of an equivalent circuit of the touch sensor panel 1 and an integration circuit 301 as a detection circuit. In the touch sensor panel, Y electrodes Y1 to YM and X electrodes X1 to XN are arranged in a matrix, and an intersection capacitance Cxy is formed at the intersection.

  The integration circuit 301 resets the power supply VHSP for charging the X electrodes X1 to XN, the switch SW2 for controlling the charging of the power supply VHSP to the X electrodes X1 to XN, the operational amplifier AMPit, the integration capacitor Cs, and the integration capacitor Cs. Switch SW1. The switch SW1 is a switch for resetting the electric charge superimposed on the capacitor Cs used for detection, and the switch SW2 is a switch for charging the power supply VHSP to the X electrodes X1 to XN.

  FIG. 4 shows an example of an input waveform to the Y electrodes Y1 to YM. As illustrated in the figure, an AC drive voltage is input to the Y electrodes Y1 to YM in the form of pulses in the order of electrode arrangement. Here, for the sake of convenience, an example in which the AC drive voltage is changed by nine pulses per Y electrode is shown.

  FIG. 5 illustrates the input pulse voltage to the Y electrodes Y1 to YM and the timing of the detection operation by the integration circuit 301. First, the switch SW2 is turned on to make a transition to the non-detection state a in which the X electrode Xn (n = 1 to N) is charged to the power supply VHSP, the switch SW1 is turned on, and the capacitor Cs is reset. Next, the switch SW1 and the switch SW2 are turned off, and a transition is made to the detection standby state b. In the detection standby state b, the X electrode Xn is not connected to the power supply VHSP, and the voltage level is held in the integrating circuit 301 having a virtual ground configuration. Then, after transitioning to the detection standby state b, a rising pulse having an amplitude Vy is input to the Y electrode Y1 (the other Y electrodes Y2 to YM are fixed at a low level). As a result, the charge (= Vy × Cxy) is moved to the X electrode Xn via the intersection capacitance Cxy on the Y electrode Y1 and input to the detection circuit 301, and the output VOUTn of the operational amplifier AMPit changes. Since the corresponding intersection capacitance Cxy decreases by the capacitance value Cf by touching with a finger, for example, when the touched X electrode is X2, the charge input to the operational amplifier AMPit of the X electrode X2 is Vy × ( Cxy−Cf), and the output VOUT2 of the operational amplifier AMPit becomes a high potential. This VOUTn (n = 1 to N) is converted into detection data of a digital value by the AD conversion circuit 304 and used for coordinate calculation or the like.

  FIG. 6 shows a mounting example of the touch sensor panel 1. Between the touch sensor panel 1 and the touch sensor panel controller 3, for example, for the Y electrodes Y1 to YM, the wiring length from the electrode closer to the controller 3 to the electrode far from the controller 3 is different, or the near side is from the right hand. While connected, the far side is connected from the left hand. For the X electrodes X1 to XN, the ends that are separated from the center of the touch sensor panel 1 that is closest to the touch sensor panel controller 3 are wired to the left and right, or the Y electrodes Y1 to YM Affected by the wiring environment between the wires. In the example shown in the figure, the touch sensor panel controller 3 is mounted on an FPC (Flexible printed circuits), but it may be mounted on the main substrate via the FPC. Considering the above, it is assumed that the detection data S_Data obtained from one surface of the touch sensor panel 1 is not the same at any position and varies depending on the mounting environment.

  FIG. 7 illustrates the target value of the output voltage VOUTn of the integrating circuit 301 and AD conversion result data (detection data) S_Data corresponding thereto. As an ideal for the detection result, the variation in the detection data S_Data due to the mounting environment described above is canceled, and the detection data S_Data for one surface when not touching is aligned with a predetermined allowable width of the value of VTG0 (VTG0 is the center) Within an allowable range ± ε of a certain range). Furthermore, it is ideal that all the detection data including the detection data at the time of touching is efficiently stored in the input range of the AD conversion circuit installed after the detection circuit 301. This figure illustrates the case where an AD converter circuit is used in which the conversion output is 10-bit precision and the full range of the input voltage is 4V.

  In this embodiment, the variation in the detection data is canceled so as to realize such an ideal for the detection data, and this is realized in the previous stage of the detection circuit 301. This will be described in detail below.

  FIG. 8 shows a specific example of the touch sensor panel 3. In the figure, the touch sensor panel 3 includes a drive circuit 300, a detection circuit 301 (301_1 to 301_N), an AD conversion circuit 302 (302_1 to 302N), and a RAM 303 for detection data, which are representatively shown. Furthermore, the touch sensor panel 3 includes a calibration circuit 304 (304_1 to 304N), a DA conversion circuit 305 (305_1 to 305_N), a line latch 306, and a RAM 307 for calibration data for offset correction. The overall control of the touch sensor panel 3 is performed by the control unit 310, and the control unit 310 and the RAMs 303 and 307 are interfaced to the subsystem microprocessor 5 via the bus interface 311.

  The drive circuit 300 drives the Y electrodes Y1 to YM with a pulsed AC drive voltage in the order of electrode arrangement. In short, the intersection capacitance is scan-driven. The detection circuit 301 inputs a detection signal from the intersection capacitance as the intersection capacitance Cxy driven by scanning through the corresponding X electrodes X1 to XN, and accumulates the signal charge. The accumulated signal charge is converted into detection data by the corresponding AD conversion circuit 302. Although there is no particular limitation, since the AD conversion circuit 302 (302_1 to 302_N) is provided for each of the X electrodes X1 to XN here, the number of conversions corresponding to the number of Y electrodes is performed for each scanning drive of the Y electrodes Y1 to YM. Data is generated in parallel. The converted detection data S_Data [y1, x1] to S_Data [yM, xN] are stored in the RAM 303. If the conversion accuracy of the AD conversion circuit is 10 bits, the detection data S_Data [y1, x1] to S_Data [yM, xN] for one surface of the touch sensor panel 3 is 10-bit data for each intersection capacitance Cxy. The amount is M × N × 10 bits in total. The detection data stored in the RAM 305 is supplied to the microphone processor 5 of the subsystem via the bus interface circuit 306, and used for digital filter calculation and coordinate calculation.

  The calibration circuits 304_1 to 304_N perform offset adjustment on the input signals of the detection circuits 301_1 to 301_M. Adjustment parameters for determining the offset adjustment amount are stored in the RAM 307 as data C_Data [y1, x1] to C_Data [yM, xN]. Here, the adjustment parameter is 8-bit data for each intersection capacitance Cxy, and the total data amount is M × N × 8 bits. The adjustment parameter C_Data is latched by the line latch 306 in data units corresponding to the intersection capacity of the Y electrode units that are scanned and driven in the electrode order. The adjustment parameters latched in the line latch 306 are converted into analog signals by the corresponding DA conversion circuits 305_1 to 305_N and supplied to the calibration circuits 304_1 to 304_N. The calibration circuits 304_1 to 304_N operate so as to cancel an undesired offset amount from the signal levels of the corresponding X electrodes X1 to XN according to the adjustment parameter.

  The control unit 310 controls operations of the drive circuit 300, the integration circuit 301, the AD conversion circuit 302, the calibration circuit 304, the DA conversion circuit 305, and the line latch 306 by using a control signal (not shown), and the RAMs 303 and 307. Access control and bus interface 311 input / output control.

  FIG. 9 illustrates an operation flow of the touch sensor panel controller 3. When the operation power is turned on (S1), the touch sensor panel controller 3 receives calibration parameter data (calibration frame data) C_Data [y1, x1] to C_Data [yM, xN] for one surface of the touch sensor panel. Obtained from the microprocessor 5 and stored in the RAM 307. Next, a counter m indicating the number of the Y electrode to be scanned is set to an initial value 1, and an adjustment parameter (calibration line data) C_Data [ym for one column corresponding to one Y electrode to be scanned and driven. , X1] to C_data [ym, xN] are transferred to the line latch (S4), the Y electrode Ym is scanned and a detection signal appears on the X electrodes X1 to XN (S5). The detection signal is converted into digital data by the AD conversion circuit 302 (S6), and the converted digital data for one column (detection line data) is stored in the RAM 303 as detection data S_Data [ym, x1] to S_Data [ym, xN]. (S7). The operations from step S4 to S7 are repeated while sequentially incrementing the counter value m until the counter value m reaches the final value M (S8, S9). When the counter value m reaches the final value M, the microprocessor 5 reads the detection data S_Data [y1, x1] to S_Data [yM, xN] from the RAM 303, and performs necessary calculations to determine the presence or absence of touch ( S10), coordinate calculation is performed using the detection data of a new surface of the touch sensor panel 1 (S11). After the coordinate calculation, the counter value m is returned to the initial value 1, and the above processing is repeated from step S4.

  Calibration frame data C_Data [y1, x1] to C_data [yM. xN] is determined when the touch sensor panel controller 3 and the touch sensor panel 1 are mounted, and the detection result at the time of non-touch even if the wiring capacitance load is different for each electrode or the wiring resistance load is different depending on the mounting environment. Matrix data for adjusting VTG0 to be uniform.

  FIG. 10 shows calibration frame data C_Data [y1, x1] to C_data [yM.y] stored in the touch sensor panel 1 and the calibration RAM 307. xN] is exemplified. For example, calibration data corresponding to the upper left (y1, x1) of the touch sensor panel is stored at the upper left address of the calibration RAM 307.

  FIG. 11 illustrates the operation timing related to the Y electrodes Y1 to Y3 in the detection operation of the touch sensor panel 3. In particular, the relationship among the detection operation, calibration data, and detection data is shown. First, immediately before the drive pulse is input to the electrode Y1, the corresponding calibration data L1 (C_Data [y1, x1] to C_Data [y1, xN]) is transferred from the calibration RAM 307 to the line latch 306, and DA conversion is performed. A circuit 301 converts the data into analog data. The calibration circuit 304 operates based on the analog data obtained by DA conversion, cancels the offset of the input signal of the detection circuit 301, and the detection circuit 301 that inputs the signal with the offset canceled is described with reference to FIGS. As a result, the detection voltages VOUT1 to VOUTN are output. The output detection voltages VOUT1 to VOUTN are transferred to the AD conversion circuit 302 and converted into detection data S_Data [y1, x1] to S_Data [y1, xN]. Stored. Next, a drive pulse is input to the electrode Y2, and at this time, the calibration data L2 (C_Data [y2, x1] to C_Data [y2, xN]) corresponding to immediately before the pulse drive is also stored from the calibration RAM 307 to the line latch 306. Forward to. Similarly, the detection operation is performed while transferring calibration data corresponding to the line latch 306 every time the Y electrode to be pulse-driven is switched.

  When the calibration RAM 307 is not built in the touch sensor panel controller 3, calibration data is transferred as needed from the microprocessor 5 of the subsystem, and during that time, the bus interface 311 is occupied and the transfer power increases. There is concern.

  FIG. 12 illustrates a configuration for controlling the current amount of the constant current source according to the adjustment parameter as an example of the calibration circuit. The current amount of the constant current source 310 — n schematically illustrated is configured to be controlled by the output current of the DA conversion circuit 305 — n.

  FIG. 13 illustrates a configuration for controlling the capacitive coupling voltage according to the adjustment parameter as an example of the calibration circuit. One capacitive electrode of the capacitive element 311 — n schematically illustrated is driven by the buffer amplifier 312 — n, and the capacitive coupling voltage applied to the other capacitive electrode is controlled according to the driving amount. The output voltage of the buffer amplifier 312 — n is controlled by the output of the DA converter circuit 305 — n.

  14 relates to a modification in which the calibration circuit 314 is configured to perform offset adjustment on the output signal of the detection circuit 301 as compared with the touch sensor panel controller of the first embodiment shown in FIG. It is a schematic explanatory drawing. In particular, in the modification of the first embodiment, the calibration circuit 314 is configured as a circuit that adjusts the addition / subtraction amount to be added to or subtracted from the output signal of the detection circuit 301 using the corresponding adjustment parameter. According to this, the offset can be easily adjusted by voltage addition / subtraction control with respect to the output of the detection circuit.

  FIG. 15 is an explanatory diagram illustrating a detection result expected in a non-touch state when adjustment by the calibration circuit 304 is not performed in the first embodiment. In FIG. 15, the same data (for example, 8'h7F) is stored in the calibration RAM 307, and the offset adjustment by the calibration circuit is substantially not performed. Detection data S_Data [y1, x1] to S_Data [y1, xN] regarding the X electrodes X1 to XN when the Y electrode Y1 is driven, and detection data S_Data [yM] regarding the X electrodes X1 to XN when the Y electrode YM is driven , X1] to S_Data [yM, xN], the detection data values vary for each X electrode.

  FIG. 16 is an explanatory diagram showing a detection result expected in a non-touch state when adjustment by the calibration circuit 304 is performed in the first embodiment. In FIG. 16, the calibration RAM 307 stores the optimum value of the calibration data, and the offset adjustment by the calibration circuit is substantially performed. In FIG. 16, detection data S_Data [y1, x1] to S_Data [y1, xN] regarding the X electrodes X1 to XN when the Y electrode Y1 is driven, and detection regarding the X electrodes X1 to XN when the Y electrode YM is driven. As represented by data S_Data [yM, x1] to S_Data [yM, xN], the detection data values for each X electrode are uniform.

  The optimization of the calibration data can be easily obtained by repeating the operation of searching for the optimum value while monitoring the detection data stored in the RAM 303 several times. In addition to the method of repeating the operation of searching for the optimum value while monitoring the detection data, if the actual circuit configuration and circuit constants are known, the calibration data is determined to be constant based on them as described in FIG. It is also possible to predict the optimum value of the calibration data based on the distribution of the detection data S_Data obtained at this time and the known information. It is assumed that the calibration data is optimized based on a predetermined command issued by the microprocessor 5 to the control unit 310. For example, an optimization process is performed on the command at the issue timing.

  According to the touch sensor panel controller 3 according to the first embodiment described above, it appears on the X electrode due to variations in capacitance components for each intersection capacitance seen from the X electrode caused by the mounting form of the touch sensor panel, etc. An adjustment parameter for canceling an undesired offset is stored in the RAM 307 on-chip in the touch sensor panel controller 3. Since the adjustment parameter held by the RAM 307 is supplied from the memory 307 to the calibration circuit 304 every time the Y electrode is switched, the variation in detection data can be adjusted for each intersection capacitance of the touch sensor panel 1.

  Furthermore, since it is not necessary for the microprocessor 5 for the subsystem to have such a RAM 307, it is necessary to frequently activate bus access for sequentially transferring adjustment parameters from the microprocessor 5 to the touch sensor panel controller 3. I don't need it.

  Further, the calibration circuit for performing the offset adjustment is disposed on the input side of the detection circuit 301, and it is only necessary to perform the offset adjustment on the input signal before amplification by the detection circuit 301. Therefore, it is not necessary to take a large adjustment amount. .

<< Embodiment 2 >>
FIG. 17 illustrates a touch sensor panel controller 3A according to Embodiment 2 of the present invention. 8 differs from the touch sensor panel controller 3 described in the first embodiment in FIG. 8 in that two RAMs 307A and 307B are provided as calibration RAMs. In particular, not only the mounting environment but also the temperature The calibration data C_Data can be easily updated when the optimum value of the calibration data changes due to environmental fluctuations due to changes in humidity or humidity.

  Each of the RAMs 307A and 307B has a storage area of M × N × 8 bits similarly to the RAM 307, and stores calibration data C_Data [y1, x1] to C_Data [yM, xN]. A write path to the RAMs 307A and 307B via the bus interface 311 is selected by switches SW1_B and SW2_B which are switch-controlled complementarily by the selection signal WS and its inverted signal. A read path from the RAMs 307A and 307B to the line latch 306 is selected by switches SW1_A and SW2_A that are complementarily switched by the selection signal RS and its inverted signal. The control of the selection signals RS and WS is not particularly limited, but is performed by the control unit 310A based on a command supplied from the microprocessor 5.

  Here, the microprocessor 5 performs calibration data update control for the RAM 307A or RAM 307B and switching control between the RAMs 307A and 307B used for the touch detection operation. That is, when the difference between the non-touch detection data S_Data [nc] and the expected value VTG0 exceeds the allowable value (| VTG0−S_Data [nc] |> ε), the microprocessor 5 sets the adjustment parameter currently used. Instead of the set, a new set of adjustment parameters is stored in the RAM 307A or 307B which is not currently in use, and control is performed to update the adjustment parameter set used thereafter. In this updating control, the microprocessor 5 calculates and stores a new set of adjustment parameters in the unused RAM 307A or 307B while keeping the currently used adjustment parameter set valid. When the stored adjustment parameter set is valid, control is performed to switch the adjustment parameter set to be used to the new adjustment parameter set.

  According to this, when referring to a detection signal in the middle of calculation of a new adjustment parameter, in a case where reliability cannot be obtained in the calculation result by mixing not only non-touch but also a touch state in the signal generation environment, Adjustment parameters that are currently valid can be temporarily used to avoid a significant drop in touch detection accuracy. This will be described in further detail.

  FIG. 18 is a flowchart of the operation mainly showing calibration data update control by the microprocessor.

  When the microprocessor 5 and the touch sensor panel controller 3A are powered on (S21), the microprocessor 5 enables the RAM 307A and notifies the touch sensor panel controller 3A that the RAM 307B is disabled (S22). As described in the first embodiment, calibration data C_Data [y1, x1] to C_Data [yM, xN] optimized for the mounting environment (room temperature, normal humidity) are acquired (S23) and used for calibration. Is stored in the RAM 307A (S24). The validity / invalidity of the RAMs 307A and 307B may be instructed using a 1-bit parameter or flag. For example, if r is the validity flag, r = 0 means that the RAM 307A is valid and 307B is invalid, and r = 1 means that the RAM 307A is invalid and 307B is valid. The validity / invalidity of the RAMs 307A and 307B indicates whether the data held by the RAMs 307A and 307B can be currently used (valid) or not (invalid) in the detection operation.

  Thereafter, the touch sensor panel controller 3A performs the detection operation as described above (S25). In the detection operation, the detection circuit 301 and the calibration circuit 304 measure the detection data S_Data for one surface of the touch sensor panel 1 (S26), and the microprocessor 5 reads the obtained detection data S_Data and determines whether or not there is a touch. (S27). When it is determined that there is a touch, the microprocessor 5 performs coordinate calculation and repeats the detection operation (S25).

  When the microprocessor 5 determines that there is no touch, if the difference between the detection data S_Data and the target value VTG0 at the time of non-touch does not exceed ε, for example, a digital value equivalent to 500 mV (YES in S29), the touch sensor The panel controller 3A is caused to perform the detection operation (S25) as it is. On the other hand, when the error exceeds the allowable value ε (NO in S29), the microprocessor 5 starts recalculation of the calibration data C_Data (S30), and causes the touch sensor panel controller 3A to perform a detection operation (S30). S25). The calibration data recalculated by the microprocessor 5 is stored in the RAM 307B which is currently invalidated (S31), and even during that time, the touch sensor panel controller 3A uses the calibration data of the RAM 307A that is currently valid to perform the detection operation. Can be done. In short, the recalculated calibration data is stored in the calibration RAM 307B, and currently valid calibration data is maintained in the RAM 307A. When it is determined that there is no touch, the frequency of the detection operation may be lowered. In this case, the detection operation (S25) may not be performed during the recalculation of the calibration data C_Data. In the above description, the difference between the detection data S_Data and the target value VTG0 at the time of non-touch is compared with ε (S29), and the microprocessor 5 starts recalculation of the calibration data C_Data (S30). However, the present invention is not limited to this, and the recalculation (S30) of the calibration data C_Data is forcibly performed by a command issued by the microprocessor 5 regardless of the result of step S29. You may do it. That is, when detecting no touch (NO in S27), the microprocessor 5 issues an instruction command to calculate and update calibration data to the touch sensor panel controller 3A without performing the result determination in step S29.

  When the newly calculated calibration data is completely stored in the invalid memory 307B, the microprocessor 5 determines whether or not the recalculation of the calibration data has failed (S32). If not, the calibration RAMs 307A and 307B are determined. Is enabled / disabled, and the detection operation can be continued using new calibration data. On the other hand, when there is a failure, the detection operation using the existing calibration data can be continued without switching between the calibration RAMs 307A and 307B. The determination of whether or not there is a recalculation failure (S32) can be made, for example, by comparing the calibration data C_Data of the same address in the calibration RAMs 307A and 307B. Judge that there was. However, it goes without saying that the determination method is not limited to this as long as it can be determined whether or not recalculation has failed.

  Therefore, a recalculation of the calibration data C_Data causes a calculation error, or there is a touch during recalculation, and halfway calibration data in the middle of the calculation, for example, the electrode Ym, is the newly calculated calibration data. However, for the electrode Ym + 1 to the electrode YM, if the calibration data was one generation before, the coordinate calculation was performed using the calibration data of the previous generation that had a track record of coordinate calculation although there was some level change. Can be implemented.

  According to the second embodiment, the following operational effects can be obtained. According to the first embodiment, after adjusting the detection data S_Data at the time of non-touch to the expected value VTG0 for each intersection capacitance Cxy of the intersection of the XY electrodes, for example, due to some external factor such as temperature, the touch sensor When the intersection capacitance Cxy increases, the detection voltage VOUTn decreases and approaches 0 V, and the detection data S_Data output from the AD conversion circuit 302 may approach 000h. Furthermore, if the detection data S_Data is shifted to the lower level as a whole, a sufficient S / N ratio cannot be ensured. In the second embodiment, the calibration data is optimized and updated when an error with respect to VTG0 is enlarged, so that it is possible to prevent the occurrence of a situation where the S / N ratio is lowered according to the operating environment.

  Although the invention made by the present inventor has been specifically described based on the embodiments, it is needless to say that the present invention is not limited thereto and can be variously modified without departing from the gist thereof.

  For example, each embodiment can be implemented in combination with each other. Alternatively, a subsystem microprocessor may be configured on a single chip by on-chip a touch sensor panel controller. The semiconductor device according to the present invention can also be realized as a liquid crystal driver with a built-in touch sensor panel controller or a touch sensor panel controller with a built-in liquid crystal driver. The semiconductor device according to the present invention may be a single chip or a multichip, and in the case of a multichip, it may be realized as a module device such as a system-in-package.

1 Touch sensor panel (TP)
2 Liquid crystal display panel (DSP)
3 Touch sensor panel controller (TPC)
4 Liquid crystal driver (DSPD)
5 Microprocessor for subsystem (SMPU)
6 Host processor (HMPU)
Y1 to YM Y electrode X1 to XN X electrode Cxy Intersection capacitance 300 Drive circuit 301 (301_1 to 301_N) Detection circuit 302 (302_1 to 302N) AD conversion circuit 303 RAM for detection data
304 (304_1 to 304N) Calibration circuit 305 (305_1 to 305_N) DA converter circuit 306 Line latch 307 RAM for calibration data
310 Control Unit 311 Bus Interface 3A Touch Sensor Panel Controller 307A, 307B Calibration RAM
310A Control unit

Claims (18)

A touch sensor panel in which a plurality of Y electrodes and X electrodes are arranged in a matrix;
A touch sensor panel controller that drives the Y electrode of the touch sensor panel and measures the capacitance value of the intersection capacitance of the Y electrode and the X electrode via the X electrode;
A microprocessor that performs coordinate calculation based on capacitance distribution data for each intersection of the Y electrode and the X electrode transferred from the touch sensor panel controller,
The touch sensor panel controller includes a plurality of detection circuits corresponding to the plurality of X electrodes,
A plurality of calibration circuits for performing offset adjustment on input signals of the plurality of detection circuits corresponding to the plurality of X electrodes;
A memory for storing adjustment parameters of the calibration circuit;
And a control circuit that supplies the adjustment parameter from the memory to the calibration circuit each time the Y electrode to be driven is switched.   The touch detection device according to claim 1, wherein the adjustment parameter is data for each intersection of the Y electrode and the X electrode.   The touch detection device according to claim 1, wherein the adjustment parameter is optimized according to a command input from the microprocessor.   The touch detection device according to claim 1, further comprising a bus interface connecting the memory to the microprocessor. The touch sensor panel controller has a drive circuit that drives the plurality of Y electrodes by supplying a pulse signal in the order of electrode arrangement,
The detection circuit detects a capacitance value of an intersection capacitance with the X electrode that intersects the Y electrode in Y electrode units to be driven,
The touch detection apparatus according to claim 4, wherein the calibration circuit inputs an adjustment parameter of a corresponding address from the memory every time the Y electrode to which the pulse signal is applied is switched.   The touch detection device according to claim 1, wherein the calibration circuit is a circuit that adjusts a current amount of a constant current source circuit connected to each X electrode by a corresponding adjustment parameter.   The touch detection device according to claim 1, wherein the calibration circuit is a circuit that adjusts a capacitive coupling voltage applied to a capacitive element connected to each X electrode according to a corresponding adjustment parameter. A touch sensor panel in which a plurality of Y electrodes and X electrodes are arranged in a matrix;
A touch sensor panel controller that drives the Y electrode of the touch sensor panel and measures the capacitance value of the intersection capacitance of the Y electrode and the X electrode via the X electrode;
A microprocessor that performs coordinate calculation based on capacitance distribution data for each intersection of the Y electrode and the X electrode transferred from the touch sensor panel controller,
The touch sensor panel controller includes a plurality of detection circuits corresponding to the plurality of X electrodes,
A plurality of calibration circuits for performing offset adjustment on output signals of the plurality of detection circuits corresponding to the plurality of X electrodes;
A memory for storing adjustment parameters of the calibration circuit;
A control circuit that supplies the adjustment parameter from the memory to the calibration circuit each time the Y electrode to be driven is switched, and
The touch detection device, wherein the calibration circuit is a circuit that adjusts an addition / subtraction amount to be added / subtracted to / from an output signal of the detection circuit using a corresponding adjustment parameter. The memory has a plurality of storage areas for storing different sets of adjustment parameters;
When the difference between the non-touch detection data and the expected value exceeds the allowable value, the microprocessor stores a new set of adjustment parameters in the memory instead of the adjustment parameter set currently used. The touch detection device according to claim 1, wherein control for updating a set of adjustment parameters to be performed is performed.   In the updating control, the microprocessor computes a new set of adjustment parameters and stores them in another storage area of the memory storage while keeping the set of adjustment parameters currently used valid. The touch detection device according to claim 9, wherein when the stored adjustment parameter set is valid, control is performed to switch the adjustment parameter set to be used to the new adjustment parameter set. A semiconductor device for measuring a capacitance value of an intersection capacitance of the Y electrode and the X electrode of a touch sensor panel in which a plurality of Y electrodes and X electrodes are arranged in a matrix,
A drive circuit for pulse-driving the Y electrode;
A plurality of detection circuits corresponding to the plurality of X electrodes;
A plurality of calibration circuits for performing offset adjustment on input signals of the plurality of detection circuits;
A memory for storing adjustment parameters of the calibration circuit;
And a control circuit that supplies the adjustment parameter from the memory to the calibration circuit each time the Y electrode to be driven is switched. The detection circuit detects a capacitance value of an intersection capacitance with the X electrode that intersects the Y electrode in Y electrode units to be driven,
The semiconductor device according to claim 11, wherein the calibration circuit inputs an adjustment parameter of a corresponding address from the memory every time the Y electrodes are driven in the order of electrode arrangement.   13. The semiconductor device according to claim 12, further comprising a bus interface that connects the memory to the outside. The memory has a plurality of storage areas for storing different sets of adjustment parameters;
14. The semiconductor device according to claim 13, wherein a storage area storing a set of adjustment parameters to be used is designated from outside via a bus interface. A microprocessor that performs coordinate calculation based on capacitance distribution data of the intersection capacitance obtained based on the output of the detection circuit;
The semiconductor device according to claim 12, wherein the microprocessor stores the adjustment parameter in the memory. The memory has a plurality of storage areas for storing different sets of adjustment parameters;
When the difference between the non-touch detection data and the expected value exceeds the allowable value, the microprocessor stores a new set of adjustment parameters in the memory instead of the set of adjustment parameters currently used. The semiconductor device according to claim 15, wherein control for updating a set of adjustment parameters to be used is performed. The memory has a plurality of storage areas for storing different sets of adjustment parameters;
The microprocessor issues a command based on non-touch detection to store a new set of adjustment parameters in the memory instead of the currently used set of adjustment parameters, and to use the adjustment parameter next. The semiconductor device according to claim 15, wherein control for updating the set is performed.   In the updating control, the microprocessor computes a new set of adjustment parameters and stores them in another storage area of the memory storage while keeping the set of adjustment parameters currently used valid. 17. The semiconductor device according to claim 16, wherein when the stored adjustment parameter set is valid, control is performed to switch the adjustment parameter set to be used to the new adjustment parameter set.

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