JP2011175451A - Capacity detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the effect of noise in a capacity detecting device such as a capacitive type touch panel susceptible to the effect of external noise. <P>SOLUTION: When electric charges charged in an electrode unit is introduced to and accumulated in a capacitor (202) more than once by electric charge redistribution, the capacitor is at first precharged in a changing direction of voltage due to accumulation of the charge. Further, in the course of operation to accumulate the charge more than once, the voltage by the accumulated charge of the capacitor is shifted in a direction reverse to the case of precharging and then the operation of accumulation is continued. By introducing the charged electric charges into the precharged capacitor, the variation of voltage produced in the capacitor due to each charge shift is reduced. During the course, the capacitor is subjected to voltage shift and then introduction of the charged electric charge is restarted, so that an amount of charged electric charges that can be accumulated in the capacitor can be increased as a whole. By respective steps, an averaged capacitance detection result can be obtained without being controlled by noise at specific time when the charged electric charges are introduced into the capacitor. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a capacitance detection device that detects a capacitance that is changed by the approach or contact of an object to be detected. For example, the present invention is applied to a capacitive touch sensor device that is used by being superimposed on a liquid crystal display (LCD). It relates to effective technology.

  In a capacitive touch panel that detects changes in the capacitance of electrodes made of transparent conductive film (ITO) due to touch of a finger, etc., as a method of detecting the change in capacitance, charging is performed from the external power supply to the electrode capacitance of the touch panel. In general, the charged charge is transferred to an external detection capacitor.

  As a method using this charge transfer, Patent Document 1 discloses a method of detecting a change in electrode capacitance by measuring an external power supply as a voltage source and measuring a charge transfer amount to the detection capacitor as a voltage, and using an external power supply as a current source. Japanese Patent Application Laid-Open No. 2004-228688 discloses a method of detecting a change in electrode capacitance by measuring the time of charge transfer to the detection capacitor.

U.S. Pat. No. 7,31,616 US Pat. No. 5,730,165

  In the method of charging the electrode capacitance of the touch panel from an external power source and transferring the charged charge to an external detection capacitor, the amount of detection signal increases by repeating the above charge and charge transfer multiple times in one detection cycle. At the same time, the influence of noise due to the specific charge transfer appears to be relatively small.

  However, in the technique of the above-mentioned patent document, since the amount of charge that moves for electrode capacitance measurement decreases with the number of movements, the voltage during the first movement is dominant in the measurement result. In short, the operation of moving the charged charge to the detection capacitor by charge redistribution is repeated and accumulated in the detection capacitor, so that naturally the amount of charge accumulated in the first charge share increases. The change in the electrode capacitance due to the contact with the electrode is very small and easily affected by external noise. Therefore, the effect of averaging the superimposed noise in one charge movement by a plurality of charge movements can be considered. It has been clarified by the present inventor that if the specific charge transfer becomes dominant with respect to the voltage to be finally measured, the averaging effect is lowered and the influence of the noise of a specific time becomes more likely.

  The present invention has been made in view of these problems, and an object of the present invention is to reduce the influence of noise in a capacitance detection device such as a capacitive touch panel that is easily affected by external noise.

  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, when the charge charged in the electrode portion is taken into the capacitor a plurality of times by charge redistribution and accumulated, the capacitor is first precharged in the direction of voltage change due to the accumulation of charge. Further, during the operation of accumulating a plurality of times, the operation of accumulating is continued after shifting the voltage due to the accumulated charge of the capacitor in the direction opposite to that in the case of precharging.

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

  That is, by taking charge charge into the precharged capacitor, the variation in voltage generated in the capacitor due to each charge movement is reduced. By restarting the charge charge capture after shifting the voltage of the capacitor in the middle, the amount of charge charge that can be accumulated in the capacitor can be increased as a whole. With each of them, it is possible to obtain an averaged capacitance detection result without being controlled by noise of a specific number of times when charging charge is taken into the capacitor.

FIG. 1 is a block diagram of an LCD display device to which a touch sensor device according to an embodiment of the present invention is applied. FIG. 2 is a block diagram showing an example of the internal configuration of the capacitive touch panel of FIG. FIG. 3 is a block diagram illustrating the internal configuration of the data line drive unit with a built-in touch panel drive unit of FIG. FIG. 4 is a logic circuit diagram illustrating the internal configuration of the capacity difference detection unit of FIG. FIG. 5 is an explanatory diagram equivalently showing a change in capacitance when touched with a finger (touch) with respect to the capacitance of each rhomboid electrode of the capacitive touch panel shown in FIG. 6 shows the first X electrode line first selection switch 51 to the 10th Y electrode line first selection switch 54, the first X electrode line second selection switch 60 to the 10th Y electrode line second selection switch 63, and the first X line shown in FIG. 12 is a timing chart illustrating details of operations of an electrode line non-select switch 69 to a 10th Y electrode line non-select switch 72; FIG. 7 is a timing chart illustrating details of the operation of the first X electrode line non-select switch 69 to the 10th Y electrode line non-select switch 72 shown in FIG. FIG. 8 is a circuit diagram illustrating the internal configuration of the first voltage conversion circuit of FIG. FIG. 9 is a first operation explanatory diagram sequentially showing the operation of the capacitance detection circuit shown in FIG. FIG. 10 is a second operation explanatory diagram sequentially showing the operation of the capacitance detection circuit shown in FIG. FIG. 11 is a third operation explanatory diagram sequentially showing the operation of the capacitance detection circuit shown in FIG. FIG. 12 is a fourth operation explanatory diagram sequentially showing the operation of the capacitance detection circuit shown in FIG. FIG. 13 is a fifth operation explanatory diagram sequentially showing the operation of the capacitance detection circuit shown in FIG. FIG. 14 is a sixth operation explanatory diagram sequentially showing the operation of the capacitance detection circuit shown in FIG. FIG. 15 is a timing chart illustrating the operation timing of the capacitance detection circuit shown in FIG. FIG. 16 is an operation explanatory diagram illustrating an accumulation waveform of charges when the precharge and voltage shift of the capture capacitor 202 are performed using the voltage converters 85 and 87 of FIG. FIG. 17 is an explanatory diagram of a comparative operation example illustrating a charge accumulation waveform when neither precharge nor voltage shift is performed.

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] A capacitance detection device according to a typical embodiment of the present invention includes an electrode portion (15, 201) that causes a capacitance change due to the approach or contact of a detection target, and charge that is charged to the electrode portion. A capacitor (202) that captures and accumulates a plurality of times by redistribution, and a measurement unit (89, 91) that measures a voltage generated by the charge accumulated in the capacitor, wherein the capacitor accumulates the charge The operation of taking in and accumulating the charge is started after being precharged in the direction of voltage change due to.

  By taking charge charge into the precharged capacitor, the variation in voltage generated in the capacitor by each charge movement is reduced. This makes it possible to obtain an averaged capacitance detection result without being governed by a specific number of noises that take charge charges into the capacitor.

  [2] In the capacitance detection device according to [1], after the capacitor is precharged in the direction of voltage change due to the accumulation of the charge and starts the operation of taking in and accumulating the charge, In the maintained state, the voltage is shifted in the direction opposite to the direction of voltage change due to the accumulation of the charges.

  By restarting the charge charge capture after shifting the voltage of the capacitor in the middle, the amount of charge charge that can be accumulated in the capacitor can be increased as a whole. This makes it possible to obtain an averaged capacitance detection result without being governed by a specific number of noises that take charge charges into the capacitor.

  [3] A capacity detection device according to another embodiment of the present invention includes an electrode section that causes a capacity change due to the approach or contact of a detection target, and a charge charged to the electrode section a predetermined number of times by charge redistribution. A capacitor that captures and accumulates; and a measurement unit that measures a voltage generated by the charge accumulated in the capacitor. The capacitor accumulates in the middle after the operation of capturing and accumulating the charge is started. In a state where the electric charge is maintained, the voltage is shifted in the direction opposite to the voltage changing direction due to the accumulation of the electric charge.

  By restarting the charge charge capture after shifting the voltage of the capacitor in the middle, the amount of charge charge that can be accumulated in the capacitor can be increased as a whole. This makes it possible to obtain an averaged capacitance detection result without being governed by a specific number of noises that take charge charges into the capacitor.

  [4] In the capacitance detecting device according to item 3, the capacitor is precharged in the direction of voltage change due to the accumulation of the charges before the operation of taking in and accumulating the charges is started.

  By taking charge charge into the precharged capacitor, the variation in voltage generated in the capacitor by each charge movement is reduced. This makes it possible to obtain an averaged capacitance detection result without being governed by a specific number of noises that take charge charges into the capacitor.

  [5] A capacity detection device according to another embodiment of the present invention includes an electrode section (15, 201) that causes a capacity change due to the approach or contact of a detection target, and a predetermined plurality of charges charged in the electrode section. A plurality of voltages selectively connected to the capacitor (202) that accumulates and accumulates and the second capacitor electrode (202b) opposite to the first capacitor electrode (202a) of the capacitor connected to the electrode portion. A node (NDa, NDb), a switching circuit (301, 303, 45) for switching the voltage node connected to the second capacitor electrode, and a measuring unit (89, 91) for measuring the voltage obtained at the first capacitor electrode And).

  Since the connection of the voltage node to the second capacitor electrode can be switched, the voltage shift operation of the capacitor electrode in the charge initial state and the charge holding state with respect to the capacitor can be performed.

  [6] In the capacitance detection device according to item 5, the switching circuit connects the first capacitor electrode to a first voltage (Vss) and connects the second capacitor electrode to a second voltage (level lower than the first voltage). -V) to perform the initialization, cut off the application of the first voltage to the first capacitor electrode after the initialization, and switch the connection to the second capacitor electrode to the first voltage, The operation of accumulating the charge of the electrode portion in the capacitor is started.

  The charge can be taken in after the capacitor is precharged, and the variation in voltage generated in the capacitor by each charge movement is reduced. This makes it possible to obtain an averaged capacitance detection result without being governed by a specific number of noises that take charge charges into the capacitor.

  [7] In the capacitance detection device according to [5], the switching circuit connects the second capacitor electrode to the first voltage, starts an operation of accumulating the charge of the electrode unit in the capacitor, and accumulates the same. In the middle of the operation, the connection to the second capacitor electrode is switched to the second voltage having a level lower than the first voltage, and then the operation of accumulating the charged charge of the electrode portion in the capacitor is continued.

  By restarting the charge charge capture after shifting the voltage of the capacitor in the middle, the amount of charge charge that can be accumulated in the capacitor can be increased as a whole. This makes it possible to obtain an averaged capacitance detection result without being governed by a specific number of noises that take charge charges into the capacitor.

  [8] In the capacitance detection device according to [5], the switching circuit connects the first capacitor electrode to a first voltage and connects the second capacitor electrode to a second voltage lower in level than the first voltage. The initialization is performed, and after the initialization, the application of the first voltage to the first capacitor electrode is cut off, and the connection to the second capacitor electrode is switched to the first voltage, and the charge of the electrode unit is The operation of accumulating in the capacitor is started, and during the accumulation operation, the connection to the second capacitor electrode is switched to the second voltage, and then the operation of accumulating the charged charge of the electrode unit in the capacitor is continued. .

  The charge charge can be taken after precharging the capacitor, and the charge charge that can be accumulated in the capacitor is increased overall by restarting the charge charge capture after shifting the voltage of the capacitor in the middle. Can do. This makes it possible to obtain an averaged capacitance detection result without being governed by a specific number of noises that take charge charges into the capacitor.

  [9] A capacitance detection device according to still another embodiment of the present invention is a capacitive touch panel (18, 19) configured by a plurality of capacitance electrodes (18, 19) that cause a capacitance change by the approach or contact of a detection target. 15), a capacitor (202) for taking in and accumulating charges charged in the capacitor electrode a predetermined number of times, and a second capacitor electrode (202a) opposite to the first capacitor electrode (202a) connected to the capacitor electrode. A plurality of voltage nodes (NDa, NDb) selectively connected to the capacitor electrode (202b); a switching circuit (301, 303, 45) for switching the voltage node connected to the second capacitor electrode; And a measurement unit (89, 91) for measuring a voltage obtained at the capacitor electrode.

  Since the connection of the voltage node to the second capacitor electrode can be switched, the voltage shift operation of the capacitor electrode in the charge initial state and the charge holding state with respect to the capacitor can be performed.

  [10] In the capacitance detection device of item 9, the switching circuit connects the first capacitor electrode to a first voltage (Vss) and connects the second capacitor electrode to a second voltage (level lower than the first voltage). -V) to perform the initialization, cut off the application of the first voltage to the first capacitor electrode after the initialization, and switch the connection to the second capacitor electrode to the first voltage, The operation of accumulating the charge on the capacitor electrode in the capacitor is started.

  The charge can be taken in after the capacitor is precharged, and the variation in voltage generated in the capacitor by each charge movement is reduced. This makes it possible to obtain an averaged capacitance detection result without being governed by a specific number of noises that take charge charges into the capacitor.

  [11] In the capacitance detection device of item 9, the switching circuit connects the second capacitor electrode to the first voltage, starts an operation of accumulating the charge of the capacitance electrode in the capacitor, and accumulates the same. In the middle of the operation, the connection to the second capacitor electrode is switched to the second voltage having a level lower than the first voltage, and then the operation of accumulating the charge on the capacitor electrode in the capacitor is continued.

  By restarting the charge charge capture after shifting the voltage of the capacitor in the middle, the amount of charge charge that can be accumulated in the capacitor can be increased as a whole. This makes it possible to obtain an averaged capacitance detection result without being governed by a specific number of noises that take charge charges into the capacitor.

  [12] In the capacitance detection device of item 9, the switching circuit connects the first capacitor electrode to a first voltage and connects the second capacitor electrode to a second voltage having a level lower than the first voltage. Performing the initialization, cutting off the application of the first voltage to the first capacitor electrode and switching the connection to the second capacitor electrode to the first voltage after the initialization, The operation of accumulating in the capacitor is started, and during the accumulation operation, the connection to the second capacitor electrode is switched to the second voltage, and then the operation of accumulating the charge of the capacitor electrode in the capacitor is continued. .

  The charge charge can be taken after precharging the capacitor, and the charge charge that can be accumulated in the capacitor is increased overall by restarting the charge charge capture after shifting the voltage of the capacitor in the middle. Can do. This makes it possible to obtain an averaged capacitance detection result without being governed by a specific number of noises that take charge charges into the capacitor.

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

  FIG. 1 shows an example of an LCD display device to which a touch sensor device according to an embodiment of the present invention is applied. In FIG. 1, 1 is a horizontal synchronizing signal, 2 is a vertical synchronizing signal, 3 is a data enable, 4 is display data, and 5 is a synchronizing clock. The vertical synchronization signal 1 is a signal of one display period (one frame period), the horizontal synchronization signal 2 is a signal of one horizontal period, and the data enable signal 3 is a signal indicating a period during which the display data 4 is valid (display effective period). All signals are input in synchronization with the synchronous clock 5. In the present embodiment, the following description will be made assuming that the display data is sequentially transferred in a raster scan format from the upper left pixel for one screen, and information for one pixel is composed of 6-bit digital data. Reference numeral 6 is a display control unit, 7 is a data line and touch panel control signal, 8 is a scanning line control signal, and the display control unit 6 is a vertical synchronization signal 1, horizontal synchronization signal 2, data enable signal 3, display data 4, and synchronization. From the clock 5, a data line and touch panel control signal 7 for display control and touch panel control and a scanning line control signal 8 for display scanning control are generated. 9 is an LCD panel, 10 is a touch panel drive unit built-in data line drive unit, 11 is a data line drive signal, 12 is a scan line drive unit, 13 is a scan line selection signal, 14 is a display pixel array, A touch panel drive unit built-in data line drive unit 10, a scan line drive unit 12, and a display pixel array 14 are provided on a single glass substrate. In the present embodiment, the data line driving unit 10 with a built-in touch panel driving unit is an LSI, and the scanning line driving unit 12 and the display pixel array 14 are described below as being formed of low-temperature polysilicon (LTPS) on a glass substrate. The touch panel drive unit built-in data line drive unit 10 generates a signal voltage to be written to the display pixel array 14 from the data line and touch panel control signal 7 among the data lines and the touch panel control signal 7 as in the prior art, and the touch panel control signal from the touch panel control signal. A signal (described later) indicating the coordinates is generated. The scanning line driving unit 12 outputs a scanning line selection signal 13 for selecting a scanning line to which the writing signal voltage output as the data line driving signal 11 is written, as in the conventional case. The display pixel array 14 writes the write signal voltage output as the data line drive signal 11 to the pixels on the line selected by the scanning line selection signal 13 as in the conventional case, and performs gradation control according to the write voltage. 15 is a capacitive touch panel, 16 is a detection electrode line, 17 is a coordinate signal, and the capacitive touch panel 15 is a substrate provided with electrode lines made of a plurality of orthogonal transparent conductive films (ITO). Each electrode line is input to the touch panel drive unit built-in data line drive unit 10 as a detection electrode line 16 and converted into a coordinate signal 17.

  FIG. 2 shows an embodiment of the internal configuration of the capacitive touch panel 15 shown in FIG. Reference numeral 18 denotes an X1-1 electrode, and 19 denotes a Y1-2 electrode, which are provided in a region other than the intersection of the X electrode line arranged in the horizontal direction and the Y electrode line arranged in the vertical direction. The present embodiment will be described below as a configuration in which regions other than the intersection are filled with diamonds having the same shape and area. 20 is a first X electrode line, 21 is a second X electrode line, 22 is a third X electrode line, 23 is a fourth X electrode line, 24 is a fifth X electrode line, 25 is a sixth X electrode line, 26 is a first Y electrode line, 27 Is the second Y electrode line, 28 is the third Y electrode line, 29 is the fourth Y electrode line, 30 is the fifth Y electrode line, 31 is the sixth Y electrode line, 32 is the seventh Y electrode line, 33 is the eighth Y electrode line, and 34 is The ninth Y electrode line 35 is a tenth Y electrode line, which is arranged so that X and Y are orthogonal to each other, and all the electrode lines are output as the detection electrode lines 16. In the present embodiment, the following description will be given on the assumption that the X electrode lines are composed of 6 and the Y electrode lines are composed of 10. Accordingly, 10 electrodes identical to the X1-1 electrode 18 and the Y1-2 electrode 19 are provided on the X electrode line and six on the Y electrode line.

  FIG. 3 shows an embodiment of the internal configuration of the touch panel drive unit built-in data line drive unit 10 shown in FIG. 36 is a data shift unit, 37 is a data start signal, 38 is a data shift clock, 39 is serial display data, and 40 is parallel display data. The data shift unit 36 is based on the data start signal 37 as in the prior art. The serial display data 39 is fetched in accordance with the data shift clock 38 and sequentially output as parallel display data 40. Reference numeral 41 denotes a one-line latch unit, 42 denotes a horizontal latch clock, 43 denotes one-line data, and the one-line latch unit 41 finishes outputting parallel display data 40 sequentially output for one line as in the conventional case. In accordance with the horizontal latch clock 42 indicating the timing to perform, the data is output as one line data 43. Reference numeral 44 denotes a D / A converter, which converts 1-line data 43, which is a digital value, into an analog value and outputs it as a data line drive signal 11 that becomes a write signal to the pixel, as in the prior art. 45 is a detection control unit, 46 is a detection switch drive signal, 47 is a coordinate conversion timing signal, 48 is a capacitance difference detection unit, 49 is a capacitance difference value, 50 is a coordinate conversion unit, and the detection control unit 45 is a capacitance difference detection The detection switch drive signal 46 for controlling the detection operation in the unit 48 and the coordinate conversion timing signal 47 for controlling the operation in the coordinate conversion unit 50 are generated. In the present embodiment, the following description will be made assuming that the detection operation and the coordinate conversion operation are performed on the basis of one horizontal period in synchronization with the horizontal latch clock 42. The capacitance difference detection unit 48 outputs a capacitance difference for each two detection electrode lines 16 as a capacitance difference value 49. The coordinate conversion unit 50 calculates the capacitance of each electrode line from the capacitance difference value 49, calculates the coordinate from the capacitance distribution state, and outputs it as the coordinate signal 17.

  FIG. 4 shows an embodiment of the internal configuration of the capacity difference detector 48 shown in FIG. 51 is a first X electrode line first selection switch, 52 is a second X electrode line first selection switch, 53 is a third X electrode line first selection switch, 54 is a 10th Y electrode line first selection switch, all shown However, the selection switches (16 in total) for selecting the first target electrode for difference detection are connected to each of the six X electrodes and the ten Y electrodes. 55 denotes a first selection switch signal, 56 denotes a first X electrode line first selection signal, 57 denotes a second X electrode line first selection signal, 58 denotes a third X electrode line first selection signal, and 59 denotes a tenth Y electrode line first selection. These are all signals, not shown in the figure, but signals for selecting the first target electrode for difference detection (16 in total) are input. The first selection switch signal 55 is a general term for the selection switch signals 56 to 59.

  60 is a first X electrode line second selection switch, 61 is a second X electrode line second selection switch, 62 is a third X electrode line second selection switch, 63 is a 10th Y electrode line second selection switch, all shown Although not shown, six X electrodes and 10 Y electrodes are connected to a selection switch (16 in total) for selecting a second target electrode for difference detection. 64 is the second selection switch signal, 65 is the first X electrode line second selection signal, 66 is the second X electrode line second selection signal, 67 is the third X electrode line second selection signal, and 68 is the tenth Y electrode line second selection. These are all signals, not shown in the figure, but signals for selecting the second target electrodes for difference detection (16 in total) are input. The second selection switch signal 64 is a general term for the selection switch signals 65 to 68.

  69 is a first X electrode line non-selection switch, 70 is a second X electrode line non-selection switch, 71 is a third X electrode line non-selection switch, 72 is a 10th Y electrode line non-selection switch, and all are not shown, 6 X electrodes and 10 Y electrodes are connected to each of the switches (total 16) that select the electrodes that are not selected for the first and second objects for differential detection and connect to GND. Is done. 73 is a non-select switch signal, 74 is a first X electrode line non-select signal, 75 is a second X electrode line non-select signal, 76 is a third X electrode line non-select signal, 77 is a 10th Y electrode line non-select signal, Although not shown in the figure, signals (total 16) for selecting electrodes that are not selected for the first target and the second target for difference detection are input. The non-selection switch signal 73 is a general term for the non-selection signals 74 to 77.

  Reference numeral 78 is a first X electrode capacity, 79 is a second X electrode capacity, 80 is a third X electrode capacity, and 81 is a 10th Y electrode capacity. Although not all shown, each electrode (16 electrodes in total) has a capacity. Is equivalently expressed. 82 is a first selection electrode line, 83 is a second selection electrode line, and the first selection electrode line 82 is one of the first X electrode line first selection switch 51 to the 10th Y electrode line first selection switch 54. The selected electrode line is connected as the first target for difference detection. For the second selection electrode line 83, one electrode line selected from the first X electrode line second selection switch 60 to the 10th Y electrode line second selection switch 63 is connected as a second target of difference detection. . 84 is an electrode line detection timing signal, 85 is a first voltage conversion circuit, 86 is a first electrode line voltage, 87 is a second voltage conversion circuit, 88 is a second electrode line voltage, and the first voltage conversion circuit 85 is The capacitance of the first selection electrode line 82 is converted into a voltage and output as a first electrode line voltage 86. The second voltage conversion circuit 87 converts the capacitance of the second selection electrode line 83 into a voltage and outputs it as a second electrode line voltage 88. 89 is a differential amplifying unit, 90 is a capacitance differential voltage, and the differential amplifying unit 89 is a differential amplifying unit having a first electrode line voltage 86 and a second electrode line voltage 88 as differential inputs. Is output as a capacitance difference voltage 90. Reference numeral 91 denotes an A / D conversion unit that converts a capacitance difference voltage 90 that is an analog value into a digital value and outputs the converted value as a capacitance difference value 49.

  FIG. 5 is a diagram equivalently showing a change in capacitance when touched with a finger (touch) with respect to the capacitance of each rhomboid electrode of the capacitive touch panel 15 shown in FIG. 92 is a detection power supply, 93 is an X electrode capacity, 94 is a Y electrode capacity, 95 is a finger, 96 is an X-finger capacity, 97 is a Y-finger capacity, and 98 is a ground capacity. When the finger 95 is not provided, only the X electrode capacitance 93 is obtained, whereas when the finger comes into contact, the Y-finger capacitance 97 and the Y electrode capacitance 94 via the X-finger capacitance 96 are combined. Become. By detecting this capacitance change, coordinate detection of the capacitive touch panel is performed.

  6 shows the first X electrode line first selection switch 51 to the 10th Y electrode line first selection switch 54, the first X electrode line second selection switch 60 to the 10th Y electrode line second selection switch 63, and the first X line shown in FIG. 14 is an embodiment of details of the operation of the electrode line non-select switch 69 to the 10th Y electrode line non-select switch 72. 99 is the first X electrode line first selection signal waveform, 100 is the second X electrode line first selection signal waveform, 101 is the fifth X electrode line first selection signal waveform, 102 is the sixth X electrode line first selection signal waveform, 103 is First Y electrode line first selection signal waveform, 104 is second Y electrode line first selection signal waveform, 105 is third Y electrode line first selection signal waveform, 106 is ninth Y electrode line first selection signal waveform, 107 is 10th Y The electrode line first selection signal waveform, 108 is the first X electrode line second selection signal waveform, 109 is the second X electrode line second selection signal waveform, 110 is the fifth X electrode line second selection signal waveform, and 111 is the sixth X electrode line. The second selection signal waveform, 112 is the first Y electrode line second selection signal waveform, 113 is the second Y electrode line second selection signal waveform, 114 is the third Y electrode line second selection signal waveform, and 115 is the ninth Y electrode line second. Selection signal waveform, 116 is the 10th Y electrode The second selection signal waveform, 117 is the first selection electrode line state, 118 is the second selection electrode line state, and the electrode line selected in one period is selected by switching the first selection and the second selection in the next period. Is done. For example, in the next period in which the first selection electrode line state 117 is the X1 electrode and the second selection electrode line state 118 is the X2 electrode, the first selection electrode line state 117 is the X2 electrode and the second selection electrode line state 118 is the X1. Each selection signal operates to be an electrode. In the present embodiment, adjacent electrode lines are selected as the first selection electrode line 82 and the second selection electrode line 83, and X1 and X2, X2 and X1 (previous replacement), X2 and X3, X3 and X2 (previous replacement). After replacement is selected, X5 and X6, X6 and X5 (first replacement), Y1 and Y2, Y2 and Y1 (first replacement), Y2 and Y3, Y3 and Y2 (first replacement) ,..., Y9 and Y10, and Y10 and Y9 (previous replacement) will be described below.

  FIG. 7 shows an embodiment of details of the operations of the first X electrode line non-select switch 69 to the 10th Y electrode line non-select switch 72 shown in FIG. 119 is a first X electrode line non-selection signal waveform, 120 is a second X electrode line non-selection signal waveform, 121 is a fifth X electrode line non-selection signal waveform, 122 is a sixth X electrode line non-selection signal waveform, and 123 is a first Y electrode line A non-selection signal waveform, 124 is a second Y electrode line non-selection signal waveform, 125 is a third Y electrode line non-selection signal waveform, 126 is a ninth Y electrode line non-selection signal waveform, and 127 is a tenth Y electrode line non-selection signal waveform. The waveform is such that an electrode line that has not selected either the first selection switch signal 55 or the second selection switch signal 64 shown in FIG. 6 is not selected. In the present embodiment, the following description will be made on the assumption that an electrode line not related to detection is connected to GND by a non-selection switch. 128 is an X1 electrode connection state, 129 is an X2 electrode connection state, 130 is an X6 electrode connection state, 131 is a Y1 electrode connection state, 132 is a Y2 electrode connection state, 133 is a Y10 electrode connection state, Indicates a state of being connected to the first selection electrode line 82 and the second selection electrode line 83, respectively. The X1 electrode line connection state 128, the X6 electrode line connection state 130, the Y1 electrode line connection state 131, and the Y10 electrode line connection state 133 at the ends of each of X and Y are the first selection and the second selection are 1 for the difference detection. In other periods, GND connection is established, and other X2 electrode line connection states 129 (same for X3 to X5) and Y2 electrode line connection states 132 (same for Y3 to Y9) are the first selection and second selection. Twice each time, the GND connection is made for the other periods.

  FIG. 8 illustrates the internal configuration of the first voltage conversion circuit 85 shown in FIG. In the figure, 201 is an electrode combined capacity, 202 is an intake capacity, 203 is an electrode charge switch, 204 is a voltage source, 305 is a negative voltage source, 205 is a detection electrode share switch, 206 is an intake capacity positive side set switch, and 301 is an intake capacity. A negative electrode side ground switch 303 is an intake capacitor negative electrode side negative voltage switch. The electrode combined capacitance 201 means a combined capacitance component that responds to touch / non-touch by the equivalent circuit shown in FIG. 5 as exemplified by electrode capacitances 78 to 81 typified by FIG. The detection electrode 201 is an electrode whose capacitance changes due to contact from the outside, and this capacitance is charged by a voltage source 204 connected via an electrode charging switch 203 described later, and is taken into a capture capacitor 202 by a detection electrode share switch 205. By being connected, an operation is performed so that the charged electric charge is taken in and transferred to the capacitor 202, and the presence or absence of contact is determined by the change in the electric charge amount.

  For convenience, one first capacitor electrode 202a of the capture electrode 202 is also referred to as a positive electrode, and the other second capacitor electrode 202b is also referred to as a negative electrode for convenience. The take-in capacitor 202 receives and accumulates charges from the aforementioned detection electrode 201 via the detection electrode share switch 205. A voltage is generated between the positive electrode and the negative electrode due to the accumulated charge amount, and the capacity is determined by detecting this voltage. The electrode charging switch 203 connects the voltage source 204 to the detection electrode 201, applies a constant voltage from the voltage source 204 when turned on, and operates so as to turn off after the same voltage as the voltage source 204 is reached. The detection electrode share switch 205 connects the detection electrode 201 and the capture capacitor 202. After the electrode charge switch 203 is turned off, the charge 205 stored in the detection electrode 201 is taken in and transferred to the capacitor 202 by turning on the switch 205. The take-in capacity positive electrode side set switch 206 is used at the time of initialization of the detection operation, and is turned on at the time of initialization to ground the positive electrode of the take-in capacity 202. An acquisition capacitor negative electrode-side negative voltage switch 303 which will be described later is also turned on at the same time, whereby a charge corresponding to the difference between the ground (ground level Vss) and the negative electrode voltage is set in the acquisition capacitor 202 as an initial value.

  The take-in capacitor negative side ground switch 301 selectively connects the electrode node NDb of the ground voltage (Vss) to the second capacitor electrode 202b, and the capacitor negative side negative voltage switch 303 connects the electrode node NDa of the negative voltage (−V). It is selectively connected to the second capacitor electrode 202b. The take-in capacity negative electrode side ground switch 301 and the take-in capacity negative electrode side negative voltage switch 303 are used in pairs, and both are connected to the negative electrode of the take-in capacity 202 and are controlled exclusively. That is, when 301 is on, 303 is always off, and conversely, when 303 is on, 301 is always off. These switches 301 and 303 have a dead period in which both switches are turned off at the moment of switching on and off, and both are turned on at the same time to prevent a short circuit. During initialization, the negative-side negative voltage switch 303 is turned on, the voltage (-V) of the negative voltage source 305 is applied to the negative electrode of the take-in capacitor, and is applied to the positive electrode by the take-up capacitor positive-side set switch 206 described above. The initial voltage is set in the take-in capacitor 202 according to the ground voltage (Vss). After the initialization period ends, the negative-side negative voltage switch is turned off, the negative-side ground switch 301 is turned on, and the negative electrode rises to the ground voltage. Since the positive electrode side is in a high impedance state connected to nowhere, the positive electrode also rises as the voltage of the negative electrode rises. From this state, the electrode charge switch 203 and the share switch 205 are alternately turned on to accumulate charges in the take-in capacitor 202. After accumulation for a certain number of times, the negative side ground switch 301 is turned off and the negative side negative voltage switch is turned on, so that the negative side voltage drops to the voltage of the negative voltage source 303, and accordingly the positive side voltage also changes to the negative power source. Drops by a voltage equal to the voltage of. Thereafter, charge accumulation in the take-in capacitor by alternately turning on the electrode charge switch 203 and the share switch 205 is restarted from the voltage on the positive electrode side that has dropped thereafter, and after a certain number of accumulations, the voltage is output as a detection result. Although not specifically shown, the second voltage conversion circuit 87 is configured in the same manner as described above.

  9 to 14 sequentially show the operation of the capacitance detection circuit shown in FIG.

  In FIG. 9, the detection electrode share switch 205 is turned off, and the take-in capacity positive electrode side set switch 206 and the take-in capacity negative electrode side negative voltage switch 303 are turned on to charge the take-in capacity 202 with a voltage determined by the negative voltage source 305. Further, the electrode charging switch 203 is turned on, and the detection electrode 201 is charged with a voltage determined by the voltage source 204.

  In FIG. 10, by turning off the take-in capacity positive side set switch 206 and the take-in capacity negative side negative voltage switch 303 and simultaneously turning on the take-in capacity negative side ground switch 301, the negative side of the take-in capacity 202 rises to the ground voltage. Since the positive voltage side holds the charged voltage, the voltage rises by the voltage of the negative voltage source 305 from the ground voltage. Next, in FIG. 11, the detection electrode share switch 205 is turned on, and the charge charged in the detection electrode 201 is captured and transferred to the capacitor 202. Next, in FIG. 12, the detection electrode share switch 205 is turned off and the electrode charge switch 203 is turned on, whereby the detection electrode 201 is charged again. By repeating the processes of FIGS. 11 and 12 a predetermined number of times, charges proportional to the capacitance of the detection electrode 201 are accumulated in the capture capacitor 202. The voltage of the take-in capacitor 202 at this time is the sum of the voltage of the negative voltage source 305 and the voltage corresponding to the charge accumulated by the operations of FIGS. Next, in FIG. 13, the negative capacity voltage of the negative capacity source 305 is set to the negative power supply voltage of the negative voltage source 305 by turning off the negative capacity ground side switch 301 and turning on the negative capacity switch 303. As a result, the voltage on the positive side drops by the negative power supply voltage. Further, the detection electrode 201 is charged by turning on the electrode charging switch 203. Next, in FIG. 14, the electrode charge switch 203 is turned off and the detection electrode share switch 205 is turned on, whereby the charge of the detection electrode 201 is taken in and transferred to the capacitor 202. At this time, since the positive voltage of the take-in capacitor 202 is lowered by the negative power supply voltage, the voltage of the transferred charge increases. By repeating the processes of FIGS. 13 and 14 a predetermined number of times, charges in proportion to the capacitance of the detection electrode 201 are accumulated in the capture capacitor 202. As a result of these operations, the sum of the voltage due to the repetition of the processes of FIGS. 11 and 12 and the voltage due to the repetition of the processes of FIGS. It does not depend on the acquired voltage.

  FIG. 15 shows the operation timing of the capacitance detection circuit shown in FIG. In the figure, 401 is a SET signal, 402 is a CGSEL signal, 403 is a CHARGE signal, 404 is a SHARE signal, 405 is a negative-side terminal VCS1 of the taking-in capacitor, and 406 is a positive-side terminal VCS2 of the taking-in capacitor 202. A SET signal 401 is a signal for operating the switch 206, and the switch 206 is turned on at a high level. The CGSEL signal 402 is a signal for operating the switches 301 and 303. When the signal is low, the switch 301 is turned on and the switch 302 is turned off. When the signal is high, the switch 301 is turned off and the switch 302 is turned on. The CHARGE signal 403 is a signal for operating the switch 205. When the CHARGE signal 403 is at a high level, the switch 205 is turned on, and the detection electrode 201 and the capturing capacitor 202 are connected to transfer charges. VCS1 of 405 and VCS2 of 406 are voltage waveforms resulting from the operation of the switches 301 and 303, VCS1 is on the negative side of 202 (switches 301 and 303 side), and VCS2 is on the positive side (switch 205 side).

  The numbers in the upper part of FIG. 15 indicate times in the timing chart. Times 0 to 14 mean one change cycle (difference detection cycle) of the first selection electrode line 82 and the second selection electrode line 83.

  At time 0, an operation corresponding to FIG. 9 is performed. When the SET signal 401 and the CGSEL signal 402 are at a high level, the voltage is set to the capture capacitor 202, and when the CHARGE signal is at a high level, the detection electrode 201 is charged. VCS1 is set to a negative voltage (-V), and VCS2 is at the ground level (Vss = 0V). At times 1 and 2, an operation corresponding to FIG. 10 is performed. When the SET signal 401 and the CGSEL signal 402 become low level, the capture capacitor 202 is disconnected from the negative voltage source 305, and the negative electrode is grounded, the VCS1 becomes the ground voltage (Vss). The level is increased by an absolute value voltage (for example, + V) (407).

  At time 3, an operation corresponding to FIG. 11 is performed, and the first charge transfer is performed. The CHARGE signal 403 becomes low level and the SHARE signal 404 becomes high level. As a result, the charge charged in the detection electrode 201 is transferred to the take-in capacitor 202. This increases the voltage of VCS2.

  At time 4, the operation corresponding to FIG. 12 is performed, and the second charge charge is performed. The SHARE signal 404 becomes low level and the CHARGE signal 403 becomes high level. As a result, the detection electrode 201 and the capture capacitor 202 are disconnected, and charging of the detection electrode 201 is started.

  At times 4-7, the operations at times 2 and 3 are repeated, and the voltage of VCS2 gradually increases.

  At time 8, the operation of FIG. 13 is performed. When the CGSEL signal 402 becomes high level (408), the voltage of VCS1 becomes negative voltage (−V) again (409), and accordingly, VCS2 on the positive side also drops by the negative voltage (410). Further, the CHARGE signal 403 is turned on, and the detection electrode 201 is charged.

  At time 9, the operation of FIG. 14 is performed. The CHARGE signal 403 becomes low level and the SHARE signal 404 becomes high level. At this time, the CGSEL signal 402 maintains a high level, and charges are transferred using the lowered VCS2. From time 10 to time 13, the operations of time 8 and time 9 are repeated. During this time, the newly transferred charge is stored in the VCS 2. Time 14 is the end point of the detection operation. At this time, the voltage VCS2 (86, 88) maintained in the conversion circuits 85 and 87 is differentially amplified by the differential amplifier 89, and the amplification result 90 is converted into digital data by the A / D converter 91. A detection result is obtained. Since the outputs 86 and 88 from the conversion circuits 85 and 87 are detection results related to the adjacent detection electrodes 201, the detection results include common-mode noise, which is differentially amplified. A difference in composite capacitance corresponding to the difference in non-touch appears in the signal 90, which makes it possible to determine whether the touch panel 15 is touched or not.

  FIG. 16 shows a charge accumulation waveform when the capture capacitor 202 is precharged and voltage shifted using the voltage converters 85 and 87 of FIG. 8, and FIG. 17 shows neither precharge nor voltage shift. The accumulated waveform of the charge is shown.

  As shown in FIG. 17, when the charge charged in one detection electrode is stored in the storage capacitor, the stored voltage is the voltage existing in the storage capacitor before storage and the voltage Vdd when charging the detection electrode. Proportional to the difference. Therefore, for example, there is a large difference between the storage voltages 501 and 502 at the first time and the fourth time. That is, the ratio of the first accumulated voltage 501 to the entire voltage 503 increases. This indicates that the entire voltage 503 is easily affected by the noise error of the first accumulated voltage, and is obtained by performing charging of the detection electrode and transfer of the charged charge to the capture capacitor a plurality of times. The effect of removing noise components due to averaging is reduced.

  On the other hand, in the case of FIG. 16, since the initial voltage 504 is set for the take-in capacitor by precharging, the accumulated voltage is suppressed to a small value from the beginning like 505. Further, by dropping the voltage on the negative electrode side of the take-in capacitor 202 halfway, the charge voltage of the take-in capacitor is lowered to a voltage 506 with respect to the ground voltage Vss, and then gradually accumulated in the take-up capacitor by charge redistribution that is reunited thereafter. The recovered voltage is recovered as 507, and the accumulated voltage obtained in the capturing capacitor 202 as a whole before and after the level shift can be seen to have a relatively small influence of noise, and the variation of the accumulated voltage is reduced. . Therefore, no matter what timing of the one-difference detection cycle, there is a great effect as a noise component removal effect by averaging obtained by charging the detection electrode and moving the charged charge to the capture capacitor a plurality of times, regardless of the timing at which noise is superimposed. Can be obtained.

  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, the electrode part that causes a capacitance change by the approach or contact of the detection target is not limited to a touch panel in which the detection electrodes are arranged in a matrix, and can be changed as appropriate. The voltage node connected to the capture capacitor is not limited to the negative voltage node and the ground voltage node, and can be changed as appropriate. In addition to performing both precharge for the capture capacitor and voltage shift performed in the middle of the difference detection cycle, only the voltage shift is performed in the case of performing only the precharge in the difference detection cycle or in the middle of the difference detection cycle. It may be the case. Further, the detection of the voltage obtained by the electric charge accumulated in the capturing capacitor is not limited to the differential detection described with reference to FIG. 4 and the like, but the voltage formed by the capturing capacitor is amplified alone and A / D converted. Also good. The present invention can be widely used for a device in which a drive driver IC of a display device of an information processing terminal such as a mobile phone, a DSC, or a PDA has a control unit of a capacitive touch panel to be attached to the surface of the display device.

DESCRIPTION OF SYMBOLS 1 ... Horizontal synchronizing signal 2 ... Vertical synchronizing signal 3 ... Data enable 4 ... Display data 5 ... Synchronization clock 6 ... Display control part 7 ... Data line and touch panel control signal 8 ... Scanning line control signal 9 ... LCD panel 10 ... Touch panel drive means Built-in data line driving means 11 ... Data line driving signal 12 ... Scanning line driving unit 13 ... Scanning line selection signal 14 ... Display pixel unit 15 ... Capacitive touch panel 16 ... Detection electrode line 17 ... Coordinate signal 18 ... X1-1 electrode DESCRIPTION OF SYMBOLS 19 ... Y1-2 electrode 20-25 ... 1st X electrode line, 2nd X electrode line, 3rd X electrode line, 4th X electrode line, 5th X electrode line, 6th X electrode line 26-35 ... 1st Y electrode line, 2nd Y Electrode line, third Y electrode line, fourth Y electrode line, fifth Y electrode line, sixth Y electrode line, seventh Y electrode line, eighth Y electrode line, ninth Y electrode line, tenth Y electrode line 36... Data shift Unit 37: Data start signal 38 ... Data shift clock 39 ... Serial display data 40 ... Parallel display data 41 ... 1 line latch unit 42 ... Horizontal latch clock 43 ... 1 line data 44 ... D / A conversion unit 45 ... Detection control unit 46 ... Detection switch drive signal 47 ... Coordinate conversion timing signal 48 ... Capacity difference detection unit 49 ... Capacity difference value 50 ... Coordinate conversion unit 51-53 ... First X electrode line first selection switch, second X electrode line first selection switch, first 3X electrode line 1st selection switch 54 ... 10th Y electrode line 1st selection switch 55 ... 1st selection switch signal 56-58 ... 1st X electrode line 1st selection signal, 2nd X electrode line 1st selection signal, 3rd X electrode line First selection signal 59 ... 10th Y electrode line first selection signal 60-62 ... 1st X electrode line 2nd selection switch, 2nd X electrode line 2nd selection switch H, third X electrode line second selection switch 63... 10th Y electrode line second selection switch 64... Second selection switch signal 65 to 67... First X electrode line second selection signal, second X electrode line second selection signal, second 3X electrode line second selection signal 68 ... 10th Y electrode line second selection signal 69 ... 1st X electrode line non-selection switch, 2nd X electrode line non-selection switch, 3rd X electrode line non-selection switch 72 ... 10th Y electrode line non-selection Switch 73 ... Non-selection switch signal 74 to 76 ... 1st X electrode line non-selection signal, 2nd X electrode line non-selection signal, 3rd X electrode line non-selection signal 77 ... 10th Y electrode line non-selection signal 78 to 80 ... 1st X electrode Capacity, 2nd X electrode capacity, 3rd X electrode capacity 81 ... 10th Y electrode capacity 82, 83 ... 1st selection electrode line, 2nd selection electrode line 84 ... Electrode line detection timing signal 85 ... 1st voltage conversion means 86 ... 1st Polar line voltage 87 ... second voltage conversion means 88 ... second electrode line voltage 89 ... differential amplification means 90 ... capacitance difference voltage 91 ... A / D conversion section 92 ... detection power supply 93 ... X electrode capacity 94 ... Y electrode capacity 99 -10 2 ... 1st X electrode line 1st selection signal waveform, 2nd X electrode line 1st selection signal waveform, 5th X electrode line 1st selection signal waveform, 6th X electrode line 1st selection signal waveform 103-107 ... 1st Y electrode Line first selection signal waveform, second Y electrode line first selection signal waveform, third Y electrode line first selection signal waveform, ninth Y electrode line first selection signal waveform, tenth Y electrode line first selection signal waveform 108-111. First X electrode line second selection signal waveform, second X electrode line second selection signal waveform, fifth X electrode line second selection signal waveform, sixth X electrode line second selection signal waveform 112-116 ... first Y electrode line second selection Signal waveform, second Y electrode line second selection signal wave , Third Y electrode line second selection signal waveform, ninth Y electrode line second selection signal waveform, tenth Y electrode line second selection signal waveform 117, 118... First selection electrode line state, second selection electrode line state 119 to 122. ... 1st X electrode line non-selection signal waveform, 2nd X electrode line non-selection signal waveform, 5th X electrode line non-selection signal waveform, 6th X electrode line non-selection signal waveform 123-127 ... 1st Y electrode line non-selection signal waveform, 1st 2Y electrode line non-selection signal waveform, 3rd Y electrode line non-selection signal waveform, 9th Y electrode line non-selection signal waveform, 10th Y electrode line non-selection signal waveform 128 to 130 ... X1 electrode connection state, X2 electrode connection state, X6 electrode Connection state 131-133: Y1 electrode connection state, Y2 electrode connection state, Y10 electrode connection state 201 ... Detection electrode 202 ... Capture capacity 203 ... Electrode charge switch 204 ... Voltage source 205 ... Detection electrode shell Switch 206 ... uptake capacity positive electrode side set switch 301 ... uptake capacity negative electrode side grounding switch 303 ... uptake capacity negative electrode side negative voltage switch 305 ... negative voltage source

Claims (12)

An electrode part that causes a capacitance change by the approach or contact of the detected object; and
A capacitor that takes in and accumulates the charge charged to the electrode unit a predetermined number of times by charge redistribution;
A measurement unit for measuring a voltage generated by the electric charge accumulated in the capacitor,
The capacitor is a capacitance detection device in which an operation of taking in and accumulating the charge is started after the capacitor is precharged in a voltage change direction due to the accumulation of the electric charge.   The capacitor is precharged in the direction of voltage change due to the accumulation of the charge, and then starts the operation of taking in and accumulating the charge. The capacitance detection device according to claim 1, wherein the voltage is shifted in a direction opposite to the direction of change. An electrode part that causes a capacitance change by the approach or contact of the detected object; and
A capacitor that takes in and accumulates the charge charged to the electrode unit a predetermined number of times by charge redistribution;
A measurement unit for measuring a voltage generated by the electric charge accumulated in the capacitor,
The capacitor is a capacitance detection device in which, after the operation of taking in and accumulating the charge is started, the voltage is shifted in the opposite direction to the voltage change direction due to the accumulation of the charge while maintaining the accumulated charge. .   The capacitance detection device according to claim 3, wherein the capacitor is precharged in a direction in which a voltage changes due to the accumulation of the charge before the operation of taking in and accumulating the charge is started. An electrode part that causes a capacitance change by the approach or contact of the detected object; and
A capacitor that takes in and accumulates a plurality of charges charged in the electrode unit, and
A plurality of voltage nodes selectively connected to a second capacitor electrode opposite to the first capacitor electrode of the capacitor connected to the electrode portion;
A switching circuit for switching the voltage node connected to the second capacitor electrode;
And a measuring unit that measures a voltage obtained at the first capacitor electrode.   The switching circuit performs the initialization by connecting the first capacitor electrode to a first voltage and connecting the second capacitor electrode to a second voltage having a level lower than the first voltage, and after the initialization, The application of the first voltage to the first capacitor electrode is cut off, and the connection to the second capacitor electrode is switched to the first voltage, and the operation of accumulating the charged charge of the electrode unit in the capacitor is started. 5. The capacity detection device according to 5.   The switching circuit connects the second capacitor electrode to a first voltage and starts an operation of accumulating the charge of the electrode unit in the capacitor, and to the second capacitor electrode during the accumulation operation. The capacitance detection device according to claim 5, wherein the operation of accumulating the charged charge of the electrode portion in the capacitor is continued after the connection of is switched to the second voltage having a level lower than the first voltage.   The switching circuit performs the initialization by connecting the first capacitor electrode to a first voltage and connecting the second capacitor electrode to a second voltage having a level lower than the first voltage, and after the initialization, The application of the first voltage to the first capacitor electrode is cut off, and the connection to the second capacitor electrode is switched to the first voltage, and the operation of accumulating the charged charge of the electrode unit in the capacitor is started. 6. The capacitance detection device according to claim 5, wherein the operation of accumulating the charge of the electrode unit in the capacitor is continued after the connection to the second capacitor electrode is switched to the second voltage during the operation to be performed. A capacitive touch panel constituted by a plurality of capacitive electrodes that cause a capacitance change due to the approach or contact of the detected object; and
A capacitor that takes in and accumulates a plurality of charges charged in the capacitor electrode; and
A plurality of voltage nodes selectively connected to a second capacitor electrode opposite to the first capacitor electrode of the capacitor connected to the capacitor electrode;
A switching circuit for switching the voltage node connected to the second capacitor electrode;
And a measuring unit that measures a voltage obtained at the first capacitor electrode.   The switching circuit performs the initialization by connecting the first capacitor electrode to a first voltage and connecting the second capacitor electrode to a second voltage having a level lower than the first voltage, and after the initialization, The application of the first voltage to the first capacitor electrode is cut off, and the connection to the second capacitor electrode is switched to the first voltage, and the operation of accumulating the charged charge of the capacitor electrode in the capacitor is started. 9. The capacity detection device according to 9.   The switching circuit connects the second capacitor electrode to the first voltage and starts an operation of accumulating the charge of the capacitor electrode in the capacitor, and to the second capacitor electrode during the accumulation operation. The capacitance detection device according to claim 9, wherein after the connection of is switched to a second voltage having a level lower than the first voltage, the operation of accumulating the charge of the capacitance electrode in the capacitor is continued.   The switching circuit performs the initialization by connecting the first capacitor electrode to a first voltage and connecting the second capacitor electrode to a second voltage having a level lower than the first voltage, and after the initialization, The application of the first voltage to the first capacitor electrode is cut off, and the connection to the second capacitor electrode is switched to the first voltage, and the operation of accumulating the charged charge of the capacitor electrode in the capacitor is started. 10. The capacitance detection device according to claim 9, wherein the operation of accumulating the charge of the capacitor electrode in the capacitor is continued after the connection to the second capacitor electrode is switched to the second voltage during the operation to be performed.

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