Touch panel and method for driving a touch panel

Abstract

To suppress electromagnetic noises irradiated from a touch panel resulting form drive of a touch electrode, while maintaining accuracy and responsiveness of touch detection.SOLUTION: A display panel 110 according to the present invention has a plurality of arranged touch electrodes TE and a driver IC11 connected to each of the touch electrodes TE. The plurality of touch electrodes TE are classified into a plurality of groups GA, GB so that electrodes belonging to the groups GA, GB different from each other should be allocated in a smaller region as compared with a detection target such as a finger. The driver IC11 alternately or successively applies a drive voltage to the touch electrodes TE of the plurality of groups GA, GB to detect a capacitance of each of the sensor electrodes TE, and then detects, based on the detected capacitance, whether or not there is any touch.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a touch panel and a method for driving the touch panel.

Background Art

[0002] For touch sensing, a touch panel applies a driving signal composed of a pulse signal of a predetermined frequency to a touch electrode. This driving signal causes electromagnetic interference noise (EMI). As an electronic device, the touch panel must maintain the EMI below a certain level.

[0003] Generally, the causes of electromagnetic interference noise (EMI) from digital circuits are: (1) when a digital signal is transmitted on a signal line, it is caused by a spike current flowing through the signal line in response to the Low / High transition of the signal; (2) when a digital signal is output from an IC circuit, it is caused by a through-current flowing inside the IC circuit; (3) when the decoupling capacitor of the IC circuit does not function sufficiently; (4) it is caused by common-mode noise due to the vulnerability of the signal GND (ground) of the device on which the IC circuit is mounted, etc.

[0004] A touch panel outputs a pulse signal from a driving IC to a touch panel electrode for touch detection. Therefore, since a spike current due to the pulse signal flows through the wiring from the driving IC to the touch panel electrode, the driving signal and signal wiring of the touch panel can cause electromagnetic interference noise (EMI). However, in a display device, since the touch panel is arranged on the display surface side, for example, if an electromagnetic shield or the like for preventing electromagnetic interference noise (EMI) is arranged on the touch panel, there is a problem that the touch detection accuracy decreases and the display visibility further deteriorates. In addition, for the pulse signal of each wiring, it is difficult to arrange a required large number of filter elements such as filter beads in a limited space, and there is a possibility of affecting the accuracy of touch detection. To prevent electromagnetic interference noise (EMI) from the touch panel, countermeasures different from electromagnetic shields and filter elements are required.

[0005] As a countermeasure for reducing electromagnetic noise radiated due to the operation of a touch panel, a driving method of switching the driving frequency has been proposed. For example, the touch display device disclosed in Patent Document 1 has a display mode for displaying an image and a touch mode for detecting a touch position. In this driving method, the period of the touch mode is divided into a plurality of unit touch periods, and in each touch period, the frequency of the touch driving signal is changed from the frequency of other unit touch periods for driving. When a touch driving signal is output to any one of the electrodes, a no-load driving signal is applied to all the other electrodes.

[0006] Further, the touch display device described in Patent Document 2 has a plurality of display periods within one frame, switches and displays the display area in each display period, and detects a touch in a non-display area.

[0007] Non-Patent Document 1 discloses that during the blank period of a display device, driving electrodes are selected by a multiplexer and sequentially scanned, and in-phase pulse signals are also applied to non-driving electrodes, data lines, and gate lines.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Non-Patent Documents

[0009]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] In the detection method described in Patent Document 1, the peak frequency may be reduced, but the noise level in other frequency bands increases. Also, since the frequency of the drive signal needs to be switched to a frequency lower than the maximum drive frequency at which touch can be detected, the number of drive voltages that can be applied during the limited display blank period decreases, and the accuracy of touch detection may decrease.

[0011] In the detection method described in Patent Document 2, it is necessary to divide the display and control each display area, resulting in a large circuit scale. Also, since the non-display area becomes the touch detection area, the timing of touch detection is different for each display area, and there are differences in responsiveness for each area.

[0012] The drive method disclosed in Non-Patent Document 1 is for reducing the influence of parasitic capacitance and does not consider electromagnetic noise. Also, the non-sensing wiring and electrodes are driven in the same phase as the sensing wiring and electrodes. For this reason, the radiated electromagnetic noise becomes large.

[0013] The present disclosure has been made in view of the above circumstances, and an object thereof is to suppress electromagnetic noise radiated from the touch panel due to driving of the touch electrodes while maintaining the accuracy and responsiveness of touch detection.

Means for Solving the Problems

[0014] To achieve the above object, the touch panel of the present disclosure includes a plurality of sensor electrodes arranged, a driver circuit connected to each sensor electrode, and is provided with the sensor electrodes are grouped into a plurality of groups such that electrodes belonging to different groups are included in a range smaller than the detection object, the driver circuit For one of the plurality of groups, one alternately or sequentially applies a driving pulse voltage to the sensor electrodes of the plurality of groups, in a state where electrodes belonging to different groups are included in a range smaller than the object to be detected detects the capacitance of each sensor electrode, and detects the presence or absence of touch based on the detected the capacitance.

[0015] It is desirable that the driver circuit applies a reference voltage to the sensor electrodes of the group to which the driving pulse voltage is not applied. For example, the sensor electrodes are arranged in a matrix and grouped so as to be adjacent to at least one of the sensor electrodes belonging to other groups, and the driver circuit alternately or sequentially applies a driving pulse voltage to the sensor electrodes of the plurality of groups.

[0016] The sensor electrodes are grouped, for example, in units of columns, rows, or individually, alternately into one or the other of two groups.

[0017] For example, the sensor electrodes are arranged in a matrix and grouped into three groups so as to belong to different groups every other one, and the driver circuit sequentially applies a driving pulse voltage to the sensor electrodes in group units. For example, the sensor electrodes are grouped in order into any of three groups in units of rows, columns, or individually.

[0018] For example, the sensor electrodes are arranged in a matrix, and one unit is formed by a plurality of the sensor electrodes. The adjacent units are grouped so as to belong to different groups. The driver circuit detects the presence or absence of a touch based on the capacitance of the sensor electrodes that are not adjacent to other units among the sensor electrodes constituting each unit. For example, the sensor electrodes form units in units of three columns, three rows, or three columns and three rows.

[0019] The driver circuit may switch the grouping of the plurality of sensor electrodes. Further, the driver circuit may switch the grouping when a control signal instructs, when a touch is not detected during a reference period, when the operation mode of the electronic device including this touch panel is a specific operation mode, or when the electromagnetic noise radiated from this touch panel is equal to or higher than a reference.

[0020] The driving method of the touch panel of the present disclosure is A method for driving a touch panel including a plurality of arranged sensor electrodes, The sensor electrodes are grouped into a plurality of groups so that electrodes belonging to different groups are included in a range smaller than the detection object, For one of the plurality of groups, one drive pulse voltage is applied to the plurality of groups Apply to the sensor electrodes alternately or sequentially and in a state where electrodes belonging to different groups are included in a range smaller than the object to be detected detect the capacitance of each sensor electrode, and detect the presence or absence of a touch based on the detected the capacitance.

Advantages of the Invention

[0021] According to the present disclosure, the sensor electrodes are divided into a plurality of groups, and a driving voltage is applied in units of groups. Therefore, compared with the case where the sensor electrodes are driven collectively, the amount of current associated with the driving pulse can be suppressed, and electromagnetic noise can be suppressed. Further, the sensor electrodes are grouped into a plurality of groups so that electrodes belonging to different groups are included in a range smaller than the detection object. Different from the case of detecting by dividing the region, it can be detected responsively, and the detection accuracy can be improved.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Embodiments for Carrying Out the Invention

[0023] Hereinafter, a touch panel and a method for driving the touch panel according to an embodiment will be described with reference to the drawings.

[0024] <Embodiment 1> With reference to FIGS. 1 to 4, a touch panel and a method for driving the touch panel according to Embodiment 1 will be described. First, with reference to FIG. 1, the configuration of a touch display device 100 according to Embodiment 1 will be described.

[0025] FIG. 1 is a schematic system configuration diagram of the touch display device 100. As shown in the figure, the touch display device 100 includes a plurality of data lines DL to which data voltages corresponding to video signals are applied, and a plurality of gate lines GL to which gate signals are applied, and includes a display panel 110 including a plurality of sub-pixels SP arranged near the intersection positions of the data lines DL and the gate lines GL. The data lines DL are connected to the sub-pixels SP via TFTs (Thin Film Transistors) not shown in the figure. A data driving circuit not shown in the figure is connected to each data line DL. Each gate line GL is connected to the gates of a plurality of TFTs in the same column and a gate driving circuit not shown in the figure. The data driving circuit applies a data voltage defining a display image of a row to be written to each data line DL. The data voltage is applied to the sub-pixel SP via the TFT of that row. The gate driving circuit sequentially applies a gate signal for turning on the TFT connected to the sub-pixel SP to which the data voltage is to be written to each gate line GL.

[0026] Touch electrodes TE for touch detection are arranged in a matrix over substantially the entire touch detection area of the display panel 110. The touch electrode TE is an example of a sensor electrode for detecting contact or proximity of a detection object.

[0027] FIG. 2 shows the configuration of the touch detection unit 120 of the touch display device 100. Here, for ease of understanding, an example is shown in which touch electrodes TE are arranged in 5 rows and 4 columns. To easily distinguish the touch electrodes TE, the touch electrode in the i-th row and j-th column is denoted by the symbol TEij. The touch electrodes TEij are grouped in a repeating pattern of one unit. Specifically, they are divided into two groups, group A GA of the first and third columns and group B GB of the second and fourth columns, in column units. Each touch electrode TEij is connected to a driver IC (Integrated Circuit) 11 via a drive signal line SL. The touch electrodes TE are arranged such that sensor electrodes belonging to different groups exist within the size of the detection object. In the present embodiment, assuming the detection object is an adult's fingertip, for example, the individual touch electrodes TE are configured from rectangular transparent electrodes with a vertical and horizontal size of 1 to 5 mm and arranged in a matrix so that touch electrodes TE belonging to two groups are arranged within 5 mm × 5 mm assumed as the size of the detection object.

[0028] The driver IC 11 is a driver circuit for detecting the presence or absence of a touch and the touch position, and is individually connected to each touch electrode TEij via the drive signal line SL. When detecting the touch position, the driver IC 11 first applies a positive drive pulse in parallel to the touch electrodes TE of group A GA, while applying a reference voltage Vc to the touch electrodes TE of group B GB. The Low voltage of the drive pulse is the reference voltage Vc, and the High voltage (drive voltage) is set to a voltage level that can detect the proximity of the detection object. However, the value of the drive voltage is not limited. The reference voltage Vc is, for example, a DC fixed voltage such as a ground voltage or a power supply voltage. However, any voltage may be used as long as it can prevent the touch electrode TE from becoming a floating state and suppress the radiated electromagnetic noise. When the driver IC 11 is a sensor circuit that detects the rise and fall of the drive pulse, by setting the reference voltage Vc to the intermediate value between the High voltage and Low voltage of the drive pulse, the influence from the electrodes of other groups can be equalized during the rise and fall, and the detection accuracy can also be optimized.

[0029] When a human finger approaches the touch electrode TE, parasitic capacitances are simultaneously formed between one or more touch electrodes TE of group A GA close to the finger and between one or more touch electrodes TE of group B GB close to the finger. When the potential of the finger is stable, a current transiently flows through the parasitic capacitance between the finger and the driven touch electrode TE of group A GA. On the other hand, when the potential of the finger is unstable, a current transiently flows from the driven touch electrode TE of group A GA to the non-driven touch electrode TE of group B GB through the parasitic capacitance and the finger. The driver IC 11 detects the parasitic capacitance of each driven touch electrode TE by, for example, monitoring the current flowing through each driven signal line SL. The driver IC 11 determines the presence or absence of a nearby finger based on whether the detected parasitic capacitance is greater than a reference value, for example. When it is determined that a finger is nearby, the coordinate position (i, j) of the finger is specified from the distribution of the parasitic capacitance.

[0030] At the next detection timing, the driver IC 11 applies a positive drive pulse in parallel to the touch electrodes TE of group B GB, applies the reference voltage Vc to the touch electrodes TE of group A GA, monitors the current flowing through each drive signal line SL, and detects the distribution of the parasitic capacitance of each driven touch electrode TE. Also at this time, the driver IC 11 determines the presence or absence of a nearby finger based on whether the detected parasitic capacitance is greater than a reference value, for example. When it is determined that a finger is nearby, the coordinate position (i, j) of the finger is specified from the distribution of the parasitic capacitance.

[0031] Thereafter, the driver IC 11 performs the same operations, i.e., i) applying a positive drive pulse to the touch electrodes TE of group A GA and applying a reference voltage Vc to the touch electrodes TE of group B GB, monitoring the current flowing through each drive signal line SL, detecting the parasitic capacitance of each touch electrode TE of group A GA, comparing the parasitic capacitance of each touch electrode TE with a reference value to determine whether a finger is near the touch electrode TE of group A GA, and identifying the coordinate position (i, j) of the finger from the distribution of the parasitic capacitance, and subsequently, ii) applying a positive drive pulse to the touch electrodes TE of group B GB and applying a reference voltage Vc to the touch electrodes TE of group A GA, monitoring the current flowing through each drive signal line SL, detecting the parasitic capacitance of each touch electrode TE of group B GB, comparing the parasitic capacitance of each touch electrode TE with a reference value to determine whether a finger is near the touch electrode TE of group B GB, and identifying the coordinate position (i, j) of the finger from the distribution of the parasitic capacitance, and repeating these operations. The driver IC 11 identifies the coordinate position (i, j) of the finger within the matrix of the touch electrodes TE from a plurality of detection distributions during the driving of group A GA and a plurality of detection distributions during the driving of group B GB at the end of the touch detection mode or the like, and outputs the result to the host device.

[0032] Next, the operation of the touch display device 100 having the above configuration will be described. As shown in FIG. 3(A), the touch display device 100 alternately repeats a display mode DM for displaying an image and a touch detection mode TM for detecting a touch position (including a proximity position).

[0033] In the display mode DM, a gate driver (not shown) sequentially applies gate pulses to the gate lines GL to turn on the TFTs in each row. The data driver applies a data voltage for instructing the gradation of each subpixel SP in the row to which the gate driver has applied the gate pulse to the data line DL. As a result, the gradation of each subpixel SP is set and maintained for one frame period. By repeating such operations for all subpixels SP, an image is displayed.

[0034] When the operation mode shifts from the display mode DM to the touch detection mode TM, the driver IC 11 starts the touch detection operation. First, the driver IC 11 groups the touch electrodes TE into group GA and group GB as shown in FIG. 2. However, at this stage, it is not necessary to newly group the touch electrodes TE. For example, if the grouping is set at the design stage of the driver IC 11, the process can proceed. In the present disclosure, "grouping" is a concept that includes such cases.

[0035] As shown in FIGS. 3(B) and (C), the driver IC 11 applies the drive signal SA shown in FIG. 3(B) to the touch electrodes TE of group GA and the drive signal SB shown in FIG. 3(C) to the touch electrodes TE of group GB. The drive signals SA and SB are signals composed of a series of positive-polarity drive pulses whose phases are shifted by approximately π from each other. The pulse width of each drive pulse is, for example, 3 to 7 μs, and here it is 5 μs. In this case, the pulse period is, for example, 3 times 15 μs. Also, the driver IC 11 detects the current flowing through each drive signal line SL, that is, the current flowing through each touch electrode TE.

[0036] In this state, as illustrated in FIGS. 4(A) and (B), assume that the finger 21 is positioned close to the upper position between the touch electrode TE23 and the touch electrode TE33. In this case, a parasitic capacitance is formed between the finger 21 and the neighboring touch electrodes TE, and the magnitude of the parasitic capacitance changes according to the distance between the finger 21 and each touch electrode TE. In FIG. 4, for ease of understanding, the parasitic capacitance C1 between the touch electrode TE32 and the finger 21 and the parasitic capacitance C2 between the touch electrode TE33 and the finger 21 are illustrated. Also, the voltage to which the drive pulse is applied is shown with hatching.

[0037] First, as shown in FIGS. 3(B) and 4(A), the driver IC 11 applies drive pulses of the drive signal SA to the touch electrodes TE in the A group GA, that is, the first and third columns, and applies the reference voltage Vc of the drive signal SB to the touch electrodes TE in the B group GB, that is, the second and fourth columns. Then, if a human finger 21 is close to the touch electrode TE, a current transiently flows through the touch electrode TE33 and the surrounding touch electrodes TE via the parasitic capacitance C2 and the human body, or the parasitic capacitance C2, the finger 21, and the parasitic capacitance C1. The driver IC 11 obtains the current distribution, that is, the parasitic capacitance distribution, by detecting the current flowing through each drive signal line SL, and obtains the position coordinates (i, j) of the finger from the obtained distribution.

[0038] Subsequently, as shown in FIGS. 3(C) and 4(B), the driver IC 11 applies drive pulses of the drive signal SB to the touch electrodes TE in the B group GB, that is, the second and fourth columns, and applies the reference voltage Vc of the drive signal SB to the touch electrodes TE in the A group GA, that is, the first and third columns. Then, if a human finger 21 is close to the touch electrode TE, a current transiently flows through the touch electrode TE32 and the surrounding touch electrodes TE via the parasitic capacitance C1 and the human body, or the parasitic capacitance C1, the finger 21, and the parasitic capacitance C2. The driver IC 11 obtains the current distribution, that is, the parasitic capacitance distribution, by detecting the current flowing through each drive signal line SL, and obtains the position coordinates (i, j) of the finger from the obtained distribution.

[0039] The driver IC 11 repeats the same operation several times. If it can be determined that there is no false detection due to external noise or the like, the driver IC 11 outputs the position coordinates (i, j) finally calculated from the detected coordinates during the drive of the A group GA and the detected coordinates during the drive of the B group GB to the host device. The calculation method can be arbitrarily selected, such as adopting an average value or a majority vote. Thereafter, the operation mode shifts to the display mode DM. During the display mode DM, the driver IC 11 outputs a constant potential or is in a high-impedance state and does not output pulses that would be a noise source.

[0040] According to such a configuration and touch detection operation, compared with a driving method that drives all touch electrodes TE synchronously and collectively, the number of driving electrodes is halved, and the radiated electromagnetic noise can be halved. Also, the entire touch detection area can be detected substantially simultaneously, and the accuracy of touch detection does not decrease due to the division of the driving area.

[0041] In addition, since a pulse voltage is applied to the touch electrode TE to be driven and a reference voltage Vc is applied to the touch electrode TE not to be driven, an electromagnetic shielding effect can be obtained by the touch electrode TE and the driving signal line SL. Furthermore, when the finger 21 approaches, a parasitic capacitance also occurs between the touch electrodes TE in a voltage constant state. Therefore, even when the finger 21 is in an electrically floating and unstable state, the presence or absence and the position when present can be accurately detected.

[0042] Although an example of detecting the finger 21 has been shown, the object to be detected can be arbitrary as long as it can form a parasitic capacitance with the touch electrode TE, such as a part of a living body, a stylus pen, a touch pen, etc. Note that the size and grouping of the touch electrodes TE are set so that sensor electrodes belonging to different groups are arranged within the size of the object to be detected according to the size of the object to be detected. Also, although an example of alternately setting the display mode DM and the touch detection mode TM has been shown, how to set the mode is arbitrary. As an example of the touch panel, a touch display device having a display function has been described, but a touch panel dedicated to touch detection without a display function may also be used.

[0043] In the above-described embodiment, the touch electrodes TE are grouped in a repeating pattern on a row-by-row basis, so that a plurality of sensor electrodes are grouped such that each sensor electrode is adjacent to at least one sensor electrode belonging to another group. This disclosure is not limited to this. For example, as in the touch detection unit 121 illustrated in FIG. 5, the touch electrodes TE may be grouped in a repeating pattern skipping one row, and drive pulses may be alternately applied. The drive signal in this case may be the same as that shown in FIGS. 3(B) and (C). In FIG. 5, the touch electrodes TE are hatched to make the grouping of the touch electrodes TE easier to understand. The same applies to the following drawings.

[0044] In the above description, an example of grouping the touch electrodes TE in a repeating pattern of a plurality of detection units such as row units or column units has been shown, but the present invention is not limited to this. For example, as in the touch detection unit 122 illustrated in FIG. 6, the touch electrodes TE may be grouped in a repeating pattern of one unit, that is, a checkered pattern, and drive pulses may be alternately applied. The drive signal in this case may be the same as that shown in FIGS. 3(B) and (C).

[0045] <Embodiment 2> In the above description, an example of dividing the touch electrodes TE into two groups and alternately applying drive pulses has been shown, but the present invention is not limited to this. It is possible to divide them into n groups, where n is any natural number of 2 or more, and apply drive pulses in order in group units. Hereinafter, an example where the number of groups n = 3 will be described.

[0046] In the touch detection unit 123 of FIG. 7, an example is shown in which the touch electrodes TE are divided into three groups: group GA, group GB, and group GC in column units. As shown in the figure, the touch electrodes TE in the first and fourth columns belong to group GA, the touch electrodes TE in the second and fifth columns belong to group GB, and the touch electrodes TE in the third and sixth columns belong to group GC. In the case of such a configuration, the touch electrodes TE are arranged such that there can be touch electrodes TE belonging to the three groups GA, GB, and GC within the size range of the detection object. For example, if the width of the finger 21 is 5 mm, it is set such that the width of the touch electrode TE × 3 < 5 mm.

[0047] As shown in FIGS. 8(A) to 8(C), the driver IC 11 sequentially applies drive pulses to the touch electrodes TE of group GA → the touch electrodes TE of group GB → the touch electrodes TE of group GC →... in this order, and applies the reference voltage Vc to the non-driven touch electrodes TE. That is, within one frame, all the touch electrodes TE are driven three times while switching the touch electrodes TE.

[0048] Also, in the touch detection unit 124 of FIG. 9, an example is shown in which the touch electrodes TE are divided into three groups: group GA, group GB, and group GC in row units. As shown in the figure, the touch electrodes TE in the first and fourth rows belong to group GA, the touch electrodes TE in the second and fifth rows belong to group GB, and the touch electrodes TE in the third and sixth rows belong to group GC. The driver IC 11 sequentially applies drive pulses to the touch electrodes TE of group GA → the touch electrodes TE of group GB → the touch electrodes TE of group GC →... in this order, and applies the reference voltage Vc to the non-driven touch electrodes TE.

[0049] Furthermore, the touch detection unit 125 in FIG. 10 shows an example of dividing the touch electrodes TE into three groups: group GA, group GB, and group GC, one by one. As shown in FIGS. 8(A) to 8(C), the driver IC 11 sequentially applies drive pulses in the order of the touch electrodes TE in group GA → the touch electrodes TE in group GB → the touch electrodes TE in group GC → ···, and applies the reference voltage Vc to the non-driven touch electrodes TE.

[0050] According to the configuration of the second embodiment, electromagnetic noise radiated can be reduced more than in the first embodiment or above. Also, similar to the first embodiment, an electromagnetic shielding effect can be obtained, and it is possible to more accurately detect a floating finger or the like.

[0051] <Embodiment 3> When the number of sensor electrodes TE increases, there is a possibility of false detection due to the influence of coupling between the sensor electrodes TE. In this embodiment, in the grouping of every n columns, every n rows, and every n vertically and horizontally, the detection results of the touch electrodes TE adjacent to the touch electrodes TE of other groups are not used for position detection, and only the detection results of the non-adjacent touch electrodes TE are used to detect the detection object, thereby reducing the influence of coupling between the touch electrodes TE. Note that n ≥ 3.

[0052] The touch detection unit 126 in FIG. 11 shows an example of dividing the touch electrodes TE into two groups with the touch electrodes TE in the first to third columns as group GA and the touch electrodes TE in the fourth to sixth columns as group GB, with the touch electrodes TE in units of three columns. In this example too, it is desirable that the width of one group GA, GB be set to the size of the detection object.

[0053] The driver IC 11 applies the drive signal SA shown in FIG. 3(B) in parallel to the touch electrodes TE in group GA, that is, the touch electrodes TE in the first to third columns, and applies the drive signal SB shown in FIG. 3(C) in parallel to the touch electrodes TE in group GB, that is, the touch electrodes TE in the fourth to sixth columns.

[0054] The driver IC 11 uses the touch electrodes TE of each second column except the outermost columns in groups GA and GB, that is, the touch electrodes TE of the second column and the fifth column for touch detection. More specifically, the driver IC 11 uses only the current transiently flowing through the touch electrodes TE of the second column and the fifth column for touch or proximity detection, and applies the drive signals SA or SB to the touch electrodes TE of the first column, the third column, the fourth column, and the sixth column, but does not detect the current flowing through these touch electrodes TE and does not use them for touch detection. Hereinafter, the touch electrode that detects current and is used for touch detection is called an effective electrode, and the touch electrode to which a drive signal is applied but the current is not detected and is not used for touch detection is called an ineffective electrode.

[0055] Next, the touch detection operation of the touch detection unit 126 will be described. The driver IC 11 applies the drive signal SA shown in FIG. 3(B) to the touch electrodes TE of group A GA and applies the drive signal SB shown in FIG. 3(C) to the touch electrodes TE of group B GB. The driver IC 11 applies drive pulses to the touch electrodes TE of group A GA, and at the timing when the reference voltage Vc is applied to the touch electrodes TE of group B GB, detects the current flowing through each drive signal line SL connected to the touch electrodes TE of the second column, obtains the current distribution, that is, the parasitic capacitance distribution, and obtains the finger position coordinates (i, j) from the obtained distribution.

[0056] Subsequently, the driver IC 11 applies the reference voltage Vc to the touch electrodes TE of group A GA, and at the timing when drive pulses are applied to the touch electrodes TE of group B GB, detects the current flowing through each drive signal line SL connected to the touch electrodes TE of the fifth column, obtains the current distribution, that is, the parasitic capacitance distribution, and obtains the finger position coordinates (i, j) from the obtained distribution. The driver IC 11 repeats the same operation during the touch detection mode.

[0057] Further, the touch detection unit 127 in FIG. 12 shows an example of dividing the touch electrodes TE into two groups, with the touch electrodes TE in the first to third rows as group GA and the touch electrodes TE in the fourth to sixth rows as group GB, in units of three rows. In this example as well, it is desirable that the width of one group GA, GB be set to < the size of the detection target object.

[0058] The driver IC 11 applies the drive signal SA shown in FIG. 3(B) to the touch electrodes TE of group GA in parallel, and applies the drive signal SB shown in FIG. 3(C) to the touch electrodes TE of group GB in parallel.

[0059] The driver IC 11 uses only the currents transiently flowing through the touch electrodes TE in the second and fifth rows as effective electrodes for touch or proximity detection, and uses the touch electrodes TE in the first, third, fourth, and sixth rows as ineffective electrodes not used for touch detection.

[0060] Also, in the touch detection unit 128 of FIG. 13, the touch electrodes TE are configured in units of nine in a 3-column and 3-row arrangement to form one unit. The plurality of units are divided into groups GA and GB such that adjacent units belong to different groups. Among the 3-column and 3-row touch electrodes TE constituting the unit, the central touch electrode TE is used as an effective electrode for touch detection, and the eight surrounding touch electrodes TE are used as ineffective electrodes. The driver IC 11 applies the drive signal SA illustrated in FIG. 3(B) to the touch electrodes TE of group GA in parallel, and applies the drive signal SB illustrated in FIG. 3(C) to the touch electrodes TE of group GB in parallel.

[0061] Driver IC 11 detects the current flowing through each drive signal line SL connected to the touch electrodes TE22 and TE55, which are the touch electrodes TE at the center of each unit, at the timing when a drive pulse is applied to the touch electrodes TE of group GA and a reference voltage Vc is applied to the touch electrodes TE of group GB, obtains the current distribution, that is, the parasitic capacitance distribution, and obtains the finger position coordinates (i, j). Subsequently, Driver IC 11 detects the current flowing through each drive signal line SL connected to the touch electrodes TE52 and TE25, which are the touch electrodes TE at the center of each unit, at the timing when a drive pulse is applied to the touch electrodes TE of group GB and a reference voltage Vc is applied to the touch electrodes TE of group GA, and obtains the finger position coordinates (i, j). Driver IC 11 repeats the same operation during the touch detection mode TM hereafter and outputs the final detection position.

[0062] According to the touch detection unit of Embodiment 3, the influence of the coupling between the touch electrodes TE can be reduced, and the detection accuracy can be improved. Note that n may be four or more. In that case, coordinate detection is performed using the touch electrode TE that is not adjacent to the touch electrodes TE of other units as the effective electrode and the touch electrode TE that is adjacent to the touch electrodes TE of other units as the invalid electrode.

[0063] <Embodiment 4> Increasing the number of groupings reduces the number of electrodes driven simultaneously, and the radiated electromagnetic noise becomes smaller. However, since the driving is switched, the detection time becomes longer. Since the blank period of the display varies depending on the input video signal, the number of groupings may be switched so as to be the corresponding touch detection period.

[0064] For example, in the touch detection unit 129 of FIG. 14, a detection unit 13 such as a noise detection unit or an operation mode detection unit is connected to the driver IC 11. When the detection unit 13 detects electromagnetic noise of a magnitude equal to or greater than a reference and / or in a preset operation mode in which electromagnetic noise is likely to occur, for example, in order to suppress the generation of electromagnetic noise, the touch electrodes TE are divided into N groups and driven in a divided manner. When the detection unit 13 detects electromagnetic noise of a magnitude less than the reference and / or in a preset operation mode in which electromagnetic noise is unlikely to occur, it may be configured to output a control signal to the driver IC 11 so as to make the number of divisions N smaller to allow an increase in electromagnetic noise.

[0065] Further, when no touch is detected for a period equal to or longer than a reference period, the driver IC 11 may increase the number of divisions N to suppress noise. In this case, the driver IC 11 may, for example, incorporate a timer, reset the timer when a touch is detected, and switch the number of divisions N when the timer counts a reference value.

[0066] The grouping of the touch electrodes TE can be arbitrarily grouped as long as electrodes belonging to different groups are included in a range smaller than the detection object such as a finger. For example, any combination of Embodiments 1 to 4 may be used, and a grouping form with three or more groups or three or more division numbers N may be adopted. With such a configuration, grouping according to the operating environment becomes possible. Also, for example, when the touch panel is incorporated into a device A and the grouping shown in FIG. 2 is not desirable from various viewpoints, the detection unit 13 may detect that it is incorporated into the device A, output a control signal, and the driver IC 11 may adopt the grouping method shown in FIG. 13 instead of the grouping method shown in FIG. 2. Further, when parasitic capacitance exists in the drive signal line SL and the touch electrode TE, the grouping method may be selected based on the parasitic capacitance detected by the detection unit 13 so as to reduce the influence of the parasitic capacitance. It may be configured such that a control signal can be supplied to the driver IC 11 according to a user's instruction.

[0067] FIG. 15 shows the result of measuring the magnetic field near the surface of the touch panel when the touch electrodes are driven by pulses. By measuring the magnetic field near the touch panel, it is possible to confirm the magnitude of the spike current flowing through the touch panel and its frequency components. The vertical axis represents the magnetic field strength in dB, and the horizontal axis represents the frequency in Hz. (1) and (2) assume general touch panel driving conditions. (1) is the case where all touch electrodes are driven by a pulse signal of 100 kHz, and (2) is the case where they are driven at 50 kHz. (3) assumes a touch panel driving condition where the driving frequency is variable, and the frequency of the pulse signal is changed from 50 kHz to 100 kHz in 5 kHz steps. (4) simply simulates the touch panel driving condition of the present disclosure (for example, the TM period in FIG. 3), showing the case where a pulse signal of 50 kHz is applied to half of the touch panel electrodes and a constant potential is applied to the other half, and the driving states of the respective touch electrodes alternate.

[0068] In the measurement result (4) shown in FIG. 15, at frequencies lower than 1 MHz, the magnetic field strength is lower than that of other measurement results. Also, in the frequency range higher than 1 MHz, the magnetic field strength is equal to or lower than the measurement results by other driving methods, and no deterioration is observed. Therefore, it was confirmed that the driving form of the touch panel of the present disclosure can suppress the spike current flowing through the touch panel and control the frequency components included in the spike current waveform. In other words, the embodiment of the present disclosure can be a means for suppressing the electromagnetic noise radiated from the touch panel and controlling the frequency of the electromagnetic noise.

[0069] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the embodiments. In the above embodiment, it has been described that the detection object is detected by detecting the current transiently flowing through the touch electrode TE to which the driving pulse is applied and then detecting the capacitance of the touch electrode TE. However, other methods than detecting the current may be used. For example, it may be an object to detect any physical quantity that varies depending on the magnitude of the capacitance formed between the detection object and the touch electrode TE, such as the amount of charge accumulated in the touch electrode TE or the detection of the capacitance of the touch electrode TE.

[0070] In the above embodiment, the reference voltage Vc is applied to the non-driven touch electrode TE, but it is also possible to set it in a floating state or apply an alternating voltage. However, a fixed DC reference voltage is desirable. For example, the touch detection device may not have a display function. Also, the grouping of the touch electrodes is not limited to the above example. That is, as long as the touch electrodes TE arranged in the detection target area can be grouped so that each touch electrode TE is adjacent to at least one electrode TE belonging to a different group, any grouping method may be adopted.

[0071] In the above embodiment, the driver IC 11 detects the presence or absence of a touch and the position of the touch. However, the driver IC 11 may transmit the capacitance distribution detected in each detection process to a host device, and the host device may be responsible for identifying the presence or absence of a touch and the touch position when a touch is present. The role sharing between the driver IC 11 and the host device is arbitrary.

[0072] In the above embodiment, in the touch detection mode TM, the number of drive pulses applied to the touch electrodes TE of each group is set to 8, but the number of pulses is arbitrary. However, from the viewpoint of detection accuracy, it is desirable to ensure 5 or more. Also, the pulse width, duty of the pulse, etc. are also arbitrary. Also, the voltage (pulse height) of the drive pulse may be appropriately selected within a range where a touch can be detected while suppressing electromagnetic noise. Although a positive-polarity pulse is exemplified as the drive pulse, the polarity is arbitrary. The driver IC may be a semiconductor device, a discrete circuit, or a processor controlled by software.

Explanation of Reference Numerals

[0073] 11 Driver IC, 13 Detection unit, 100 Touch display device, 110 Display panel, 120 - 129 Touch detection unit, TE Touch electrode (sensor electrode), SL Drive signal line.

Claims

1. A plurality of sensor electrodes arranged, A driver circuit connected to each sensor electrode, Comprising: The sensor electrodes are grouped into a plurality of groups such that electrodes belonging to different groups are included in a range smaller than the object to be detected. The driver circuit alternately or sequentially applies one drive pulse voltage to the sensor electrodes of the plurality of groups, detects the capacitance of each sensor electrode in a state where electrodes belonging to different groups are included in a range smaller than the object to be detected, and detects the presence or absence of touch based on the detected capacitance. A touch panel.

2. The driver circuit applies a reference voltage to the sensor electrodes of the group to which the drive pulse voltage is not applied. The touch panel according to claim 1.

3. The sensor electrodes are arranged in a matrix and are grouped such that each is adjacent to at least one of the sensor electrodes belonging to other groups. The driver circuit alternately or sequentially applies a drive pulse voltage to the sensor electrodes of the plurality of groups. The touch panel according to claim 1 or 2.

4. The sensor electrodes are grouped into one or the other of two groups alternately in column units, row units, or individually. The touch panel according to any one of claims 1 to 3.

5. The sensor electrodes are arranged in a matrix and are grouped into three groups such that they belong to different groups every other one. The driver circuit sequentially applies a drive pulse voltage to the sensor electrodes in group units. The touch panel according to any one of claims 1 to 3.

6. The sensor electrodes are grouped into any one of three groups sequentially in row units, column units, or individually. The touch panel according to claim 5.

7. The sensor electrodes are arranged in a matrix, One unit is formed by a plurality of the sensor electrodes and is grouped such that adjacent units belong to different groups. The driver circuit detects the presence or absence of touch based on the capacitance of the sensor electrodes that are not adjacent to other units among the sensor electrodes constituting each unit. The touch panel according to claim 1 or 2.

8. The sensor electrodes form units in 3-column units, 3-row units, or 3-column 3-row units. The touch panel according to claim 7.

9. The driver circuit switches the grouping of the plurality of sensor electrodes. The touch panel according to any one of claims 1 to 8.

10. The driver circuit switches the grouping when a control signal so indicates, when no touch is detected during a reference period, when the operation mode of an electronic device including this touch panel is a specific operation mode, or when the electromagnetic noise radiated from this touch panel is equal to or higher than a reference. The touch panel according to claim 9.

11. A method for driving a touch panel including a plurality of sensor electrodes arranged, wherein the sensor electrodes are grouped into a plurality of groups such that electrodes belonging to different groups are included in a range smaller than a detection target object, applying one drive pulse voltage to the sensor electrodes of the plurality of groups alternately or sequentially for one of the plurality of groups, detecting the capacitance of each sensor electrode in a state where electrodes belonging to different groups are included in a range smaller than a detection target object, and detecting the presence or absence of a touch based on the detected capacitance. A method for driving a touch panel.

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