JP2024090411A - Sensing method, touch panel drive device, and touch panel device - Google Patents

Abstract

[Problem] The degradation of touch detection performance is suppressed even when water adheres to the touch panel surface. [Solution] A sensing method for a touch panel drive device capable of performing a first sensing in which a pair of adjacent transmission signal lines and a pair of adjacent reception signal lines are sequentially selected on a touch panel to detect the amount of change in capacitance during a stabilization period and a sensing period, and a second sensing in which the selection state of the transmission signal lines and reception signal lines is different from that in the first sensing and a second sensing is performed to detect the change in capacitance between the reception signal lines and ground during the sensing period. The second sensing is performed to obtain an evaluation value according to the signal strength of the obtained detection signal, and it is determined whether or not the detection signal is due to the influence of water based on the change in the evaluation value over time. If it is determined that the detection signal is not due to the influence of water, the first sensing is performed, and a coordinate calculation is performed based on the obtained detection signal to output detection information. [Selected Figure] Figure 14

Description

The present invention relates to a touch panel sensing method, a touch panel drive device that drives a touch panel, and a touch panel device having a touch panel and its drive device.

Various technologies related to touch panels are known, and the following Patent Document 1 discloses a sensing technology that improves resolution by simultaneously sensing two sets of signal lines (electrodes) (a pair of transmission signal lines and a pair of reception signal lines) to detect the touch operation position.

JP 2014-219961 A

When touch panels are used in agricultural machinery, construction machinery, industrial equipment, and the like, they are required to be able to properly detect the touch position even when water adheres to the touch panel surface.
However, if a large amount of water adheres to the surface of the touch panel, it may be erroneously determined to be a touch operation. For example, when the detection sensitivity of the touch panel is increased, the intensity of the detection signal at the moment when a large amount of water adheres to the touch panel may be similar to the intensity of the detection signal in the case of a touch operation by a finger.

Therefore, the present invention aims to enable highly accurate touch operation detection even in an environment where water may adhere to the touch panel surface.

The sensing method of the present invention is a sensing method for a touch panel driving device capable of performing first sensing on a touch panel, in which a pair of adjacent transmission signal lines and an adjacent pair of receiving signal lines are sequentially selected and scanned to detect the amount of change in capacitance between a stabilization period and a sensing period, and second sensing in which the selection state of the transmission signal lines and the receiving signal lines is different from that of the first sensing and a scan is performed to detect a change in capacitance between the receiving signal lines and ground during the sensing period, and the sensing method includes a determination procedure of performing the second sensing, calculating an evaluation value corresponding to the signal strength of the obtained detection signal, and determining whether or not the detection signal is due to the influence of water based on the change in the evaluation value over time, and a first calculation procedure of performing the first sensing, and performing a coordinate calculation based on the obtained detection signal to output detection information if it is determined that the detection signal is not due to the influence of water.
Since the signal strength of the detection signal may be similar between a touch operation and a case where water droplets or a large amount of water are present, a determination is made based on the change in the evaluation value over time.

The touch panel drive device and touch panel device according to the present invention are devices that execute the above sensing method, and are equipped with a control device that performs the second sensing, calculates an evaluation value according to the signal strength of the obtained detection signal, and determines whether or not the detection signal is due to the influence of water based on the change in the evaluation value over time, and performs the first sensing, performs coordinate calculations based on the obtained detection signal, and outputs detection information when it is determined that the detection signal is not due to the influence of water.

According to the present invention, by determining the presence or absence of water influence from the change over time of the evaluation value of the signal strength during the second sensing, it is possible to accurately determine whether the influence is due to a touch operation or water. As a result, by performing the first sensing when there is no influence of water, it is possible to avoid false detection due to water.

1 is a block diagram showing a configuration of a touch panel and a touch panel drive device according to an embodiment of the present invention; FIG. 2 is an explanatory diagram of a sensing configuration of the touch panel according to the embodiment. 2 is an explanatory diagram of a transmission circuit and a reception circuit of the touch panel drive device according to the embodiment. FIG. FIG. 2 is an explanatory diagram of a configuration for switching capacitance of a receiving circuit according to an embodiment; FIG. 10 is an explanatory diagram of a block of touch signal detection in response to scanning according to an embodiment. 10A and 10B are explanatory diagrams of a touch position with respect to a pair of signal lines according to an embodiment; 5 is an explanatory diagram of a detection pattern in a block according to the embodiment. FIG. FIG. 4 is an explanatory diagram of a first sensing according to the embodiment. FIG. 11 is an explanatory diagram of a second sensing according to the embodiment. 11A and 11B are diagrams illustrating detection accuracy in second sensing according to the embodiment. 10A and 10B are diagrams illustrating detection accuracy in the first sensing according to the embodiment. 11A and 11B are explanatory diagrams of signal changes at the time of finger touch in the second sensing in the embodiment. 13A and 13B are diagrams illustrating a change in signal when a large amount of water adheres in the second sensing of the embodiment. 11 is a flowchart of a sensing process according to the embodiment.

Hereinafter, embodiments of the present invention will be described in the following order.
1. Configuration of the touch panel device
2. First sensing and second sensing
<3. Processing example>
4. Effects and Modifications of the Embodiments

1. Configuration of the touch panel device
FIG. 1 shows an example of the configuration of a touch panel device 1 according to an embodiment.
The touch panel device 1 is attached to various devices as a user interface device. Here, various devices include, for example, electronic devices, communication devices, information processing devices, manufacturing equipment, machine tools, vehicles, aircraft, building equipment, agricultural equipment, construction equipment, and other devices in a wide variety of fields. The touch panel device 1 is employed as an operation input device used for user operation input in these various equipment products.
In particular, the touch panel device 1 of the embodiment can suppress a decrease in detection accuracy even when water droplets adhere to the touch panel, making it suitable for installation on equipment that operates outdoors or indoors in places where water may be present.

Figure 1 shows a touch panel device 1 and a product side MCU (Micro Control Unit) 90, which refers to a control device in the equipment to which the touch panel device 1 is attached. The touch panel device 1 operates to supply information on the user's touch panel operation to the product side MCU 90.

The touch panel device 1 has a touch panel 2 and a touch panel drive device 3. The touch panel drive device 3 has a sensor IC (Integrated Circuit) 4 and an MCU 5.

The touch panel driving device 3 is connected to the touch panel 2 via a touch panel side connection terminal portion 31. The touch panel driving device 3 drives (senses) the touch panel 2 via this connection.
When mounted on an apparatus as an operation input device, the touch panel driving device 3 is connected to the product side MCU 90 via the product side connection terminal unit 32. Through this connection, the touch panel driving device 3 transmits sensed operation information to the product side MCU 90.

The sensor IC 4 in the touch panel drive device 3 has a transmission circuit 41, a reception circuit 42, a multiplexer 43, an interface register circuit 44, and a power supply circuit 45.

The transmission circuit 41 of the sensor IC 4 outputs a transmission signal to a terminal in the touch panel 2 selected by the multiplexer 43. The reception circuit 42 receives a signal from the terminal in the touch panel 2 selected by the multiplexer 43 and performs necessary comparison processing, etc.

FIG. 2 shows a schematic diagram of a connection state between the transmission circuit 41, the reception circuit 42, the multiplexer 43 and the touch panel 2. As shown in FIG.
The touch panel 2 has n Y electrodes 21-1 to 21-n and m X electrodes 22-1 to 22-m arranged on a panel plane that forms a touch surface.
When there is no need to distinguish between the Y electrodes 21-1 to 21-n and the X electrodes 22-1 to 22-m, they will be collectively referred to as the "Y electrodes 21" and the "X electrodes 22."

In this embodiment, two sensing methods are performed as first sensing and second sensing, as described later.
In the first sensing, the Y electrodes 21 are used as transmitting electrodes, that is, as transmitting signal lines, and the X electrodes 22 are used as receiving electrodes, that is, as receiving signal lines.
In the second sensing, the Y electrodes 21 and the X electrodes 22 are sometimes used as transmission signal lines and sometimes used as reception signal lines, respectively.

Below, we will explain the first sensing along with the configuration of the touch panel device 1, in which case the Y electrode 21 is the transmission signal line and the X electrode 22 is the reception signal line.

The Y electrodes 21-1...21-n and the X electrodes 22-1...22-m may be arranged to intersect as shown in the figure, or may be arranged so that no intersection occurs, as in a so-called single-layer structure. In either case, a touch operation surface is formed within the area in which the Y electrodes 21 and X electrodes 22 are arranged, and the structure is such that the operation position is detected by the change in capacitance during a touch operation.

In FIG. 2, only a portion of the capacitance generated between the Y electrode 21 and the X electrode 22 is illustrated (capacitances C22, C23, C32, and C33), but capacitance generated between the Y electrode 21 and the X electrode 22 (for example, capacitance at the intersection position) exists over the entire touch operation surface, and the position where the capacitance change occurs due to the touch operation is detected by the receiving circuit 42.

The transmission circuit 41 outputs a transmission signal to a transmission signal line (Y electrodes 21-1 to 21-n) selected by the multiplexer 43. In this embodiment, the multiplexer 43 performs scanning by selecting adjacent Y electrodes 21 two at a time.
The receiving circuit 42 receives a receiving signal from a receiving signal line (X electrodes 22-1 to 22-m) selected by the multiplexer 43. In this embodiment, the multiplexer 43 selects two adjacent X electrodes 22 at each timing.
The sensing operation by the transmission circuit 41 and the reception circuit 42 will be described later.

1, various setting information for the transmission circuit 41, the multiplexer 43, the reception circuit 42, and the power supply circuit 45 is written by the MCU 5 to the interface register circuit 44 of the sensor IC 4.
The operations of the transmission circuit 41 , the multiplexer 43 , the reception circuit 42 , and the power supply circuit 45 are controlled by setting information stored in the interface register circuit 44 .
The interface register circuit 44 also stores the detection value (for the sake of explanation, also referred to as the “RAW value”) detected by the receiving circuit 42 so that the MCU 5 can acquire it.

The power supply circuit 45 generates a driving voltage AVCC and the like and supplies it to the transmitting circuit 41 and the receiving circuit 42. As will be described later, the transmitting circuit 41 applies a pulse using the driving voltage AVCC and the like to a transmission signal line (e.g., the Y electrode 21) selected by the multiplexer 43.
During sensing operation, the receiving circuit 42 also applies a driving voltage AVCC or the like to a receiving signal line (for example, the X electrode 22) selected by the multiplexer 43.
The driving voltage AVCC shown in FIG. 1 is a general term for driving voltages AVCC1, AVCC2, AVCC3, AVCC4, etc., which will be described later.

The MCU 5 sets and controls the sensor IC 4. Specifically, the MCU 5 writes necessary setting information to an interface register circuit 44, thereby controlling the operation of each part of the sensor IC 4.
Furthermore, the MCU 5 obtains the RAW value from the receiving circuit 42 by reading it out from the interface register circuit 44. The MCU 5 then performs coordinate calculation using the RAW value, and performs processing to transmit the coordinate value as touch operation position information by the user to the product side MCU 90.

In FIG. 1, the memory 5M in the MCU 5 collectively shows the RAM area, ROM area, non-volatile storage area, etc. This memory 5M is used to store the setting information to be provided to the interface register circuit 44. The memory 5M is also used as a temporary storage area for the detected RAW values and the corresponding coordinate values as touch operation position information.

In addition, FIG. 1 shows a judgment control unit 5a and a detection calculation unit 5b in the MCU 5. These are part of the processing functions realized by a program (firmware, etc.) in the MCU 5, and show functions provided specifically for the processing of this embodiment.

The judgment control unit 5a is a function that judges touches made directly with a finger on the touch panel 2 (hereinafter also referred to as "finger touch") and touches made with a gloved hand (hereinafter also referred to as "glove touch"), and controls processing to judge the effects of adhesion of water.

For example, the determination control unit 5a has a processing function of selecting the first sensing mode or the second sensing mode, and selecting a mode from among a normal mode, a high sensitivity mode, and a water mode.
The normal mode and high sensitivity mode here refer to gain setting modes for the touch signal strength set by the receiving circuit 42, with the normal mode being a mode in which the gain is set as normal sensitivity and the high sensitivity mode being a mode in which the gain is set as high sensitivity. The normal mode has a lower sensitivity than the high sensitivity mode. The water mode is a mode that is executed when it is determined that a large amount of water is attached.
The determination control unit 5a determines which mode is appropriate for a touch operation and performs selection control.

The detection calculation unit 5b is a processing function that generates information indicating the touched position based on the RAW value obtained by scanning performed in the setting state of the mode selected by the judgment control unit 5a. In other words, it performs coordinate calculations using the RAW value and performs processing to obtain coordinate values as information on the user's touch operation position.

The functions of the judgment control unit 5a and the detection calculation unit 5b perform the processing shown in FIG. 14, which will be described later.

The first sensing operation by the touch panel device 1 having the above configuration will be described.
3, the operation of the transmission circuit 41 and the reception circuit 42 for the touch panel 2 will be described. In the figure, two transmission signal lines (Y electrodes 21-2, 21-3) and two reception signal lines (X electrodes 22-2, 22-3) are shown in the touch panel 2.

In the case of the first sensing of this embodiment, the transmitter circuit 41 and receiver circuit 42 detect touch operations by transmitting and receiving signals from two adjacent electrodes, one each, for the Y electrodes 21 and the X electrodes 22 as shown in FIG. 2 above. In other words, a pair of Y electrodes 21 and a pair of X electrodes 22 (2 x 2) are used as a basic cell, and detection scanning is performed sequentially on a cell-by-cell basis. FIG. 3 shows a portion of one of these cells.

The transmission circuit 41 outputs a driving voltage AVCC1 to two Y electrodes 21 (Y electrode 21-2 and Y electrode 21-3 in the illustrated example) from drivers 411 and 412. That is, the transmission signals T+ and T-, which are the outputs of the drivers 411 and 412, are supplied to the Y electrode 21-2 and Y electrode 21-3 selected by a multiplexer 43.
The driving voltage AVCC1 is a voltage generated by the power supply circuit 45 in FIG.

In this case, the transmission circuit 41 sets the transmission signal T+ from the driver 411 to a low level (hereinafter referred to as "L level") during the idle period, as shown in the figure. For example, it may be set to 0 V. Then, during the following active period, it sets it to a high level (hereinafter referred to as "H level"). In this case, specifically, the drive voltage AVCC1 is applied as the H level signal.

In addition, in the transmission circuit 41, the transmission signal T- from the other driver 412 is set to H level (application of the drive voltage AVCC1) during an idle period, and is set to L level during the subsequent active period.
Here, the idle period is a period during which the potentials of the receiving signals R+, R- are stabilized, and the active period is a period during which changes in the potentials of the receiving signals R+, R- are sensed.

During this idle period and active period, the receiving circuit 42 receives the receiving signals R+ and R- from the two X electrodes 22 selected by the multiplexer 43 (X electrodes 22-3 and 22-2 in the illustrated example).

The receiving circuit 42 includes a comparator 421 , a reference capacitance section 422 , switches 423 and 425 , a measurement capacitance section 424 , an arithmetic control section 426 , and voltage selection sections 427 and 428 .
The reception signals R+, R- from the two reception signal lines (X electrodes 22) are received by a comparator 421. The comparator 421 compares the potentials of the reception signals R+, R- and outputs the comparison result to the calculation control unit 426 at an H level or an L level.

One of the drive voltages VSS, AVCC4, AVCC3, and AVCC2 is applied to one end of the capacitor constituting the reference capacitance section 422 via a voltage selection section 427. These drive voltages are generated by the power supply circuit 45 in FIG.
The other end of the capacitor that constitutes the reference capacitance section 422 is connected to the + input terminal of the comparator 421 via a terminal Ta of the switch 423 .

One of the driving voltages VSS, AVCC4, AVCC3, and AVCC2 is applied to one end of the capacitor constituting the measuring capacitance section 424 via a voltage selection section 428. Note that the voltage selection section 428 selects the same voltage as the voltage selection section 427.
The other end of the capacitor that constitutes the measuring capacitance section 424 is connected to the negative input terminal of the comparator 421 via a terminal Ta of the switch 425 .

In the idle period, the switches 423 and 425 select the terminal Ti, so that the + input terminal (X electrode 22-3) and - input terminal (X electrode 22-2) of the comparator 421 are grounded and the reception signals R+ and R- are at ground potential.
The switches 423 and 425 select the terminal Ta during the active period. Therefore, the drive voltage AVCC (for example, the drive voltage AVCC2) is applied to the + input terminal (X electrode 22-3) and - input terminal (X electrode 22-2) of the comparator 421 during the active period.

3, the waveforms of the reception signals R+ and R- when the cell is in an untouched state are shown by solid lines. During the idle period, the switches 423 and 425 select the terminal Ti, so that the reception signals R+ and R- are stabilized at a certain potential (ground potential).
In the active period, the switches 423 and 425 select the terminal Ta, and the drive voltage AVCC (for example, the drive voltage AVCC2) is applied to the X electrodes 22-3 and 22-2. This causes the potential of the reception signals R+ and R- to rise by ΔV. In a untouched state, this potential rise of ΔV occurs in both the reception signals R+ and R-.

On the other hand, in the transmission circuit 41, when the active period begins, the transmission signal T+ rises and the transmission signal T- falls as described above. As a result, when a touch operation is performed, the degree of increase in the potential of the reception signals R+ and R- changes.
If the A1 position that affects the capacitance C22 is touched, the potential of the reception signal R- rises by ΔVH during the active period as indicated by the dashed line.
Moreover, if the position A2 where the capacitance C32 changes is touched, the potential of the reception signal R- rises by ΔVL indicated by the dashed line during the active period.
In this way, depending on the touch operation position on the cell, the amount of change in potential of the reception signal R- becomes larger or smaller than the amount of change in potential (ΔV) of the reception signal R+.
The comparator 421 compares these received signals R+ and R-.

The potential difference between the receiving signals R+ and R- that changes in this way may itself be output as a RAW value (detection result), but in this embodiment, the receiving circuit 42 changes the setting of the capacitance value of the measurement capacitance unit 424 so that the calculation control unit 426 can balance the voltages of the receiving signals R+ and R- to obtain the RAW value.

The arithmetic and control unit 426 controls the on/off of the switches 423 and 425 .
The calculation control section 426 also controls the switching of the capacitance value of the measuring capacitance section 424 by the bit signal BS.
In addition, the calculation control unit 426 can set the detection sensitivity mode of the touch signal by controlling the switching of the capacitance value of the reference capacitance unit 422 using the mode control signal SS. The capacitance of the reference capacitance unit 422 is a fixed value during scanning, but is switched to change the sensitivity mode.

The processing of the arithmetic control unit 426 is performed in accordance with the setting information written in the interface register circuit 44. That is, the processing is performed based on the operation setting by the MCU 5.
The arithmetic control unit 426 also monitors the output of the comparator 421 and calculates a RAW value. The RAW value calculated by the arithmetic control unit 426 is written to the interface register circuit 44, so that the MCU 5 can obtain it.

The measurement capacitance section 424, indicated by the symbol of a variable capacitor in Fig. 3, is configured to have a plurality of capacitors, for example, 11 capacitors CM (capacitor CM0 to capacitor CM10) and 11 switches SW (switch SW0 to switch SW10) as shown in Fig. 4. Similarly to the measurement capacitance section 424, the reference capacitance section 422 also has 11 capacitors CM (capacitor CM20 to capacitor CM30) and 11 switches SW (switch SW20 to switch SW30).
The terms "capacitor CM" and "switch SW" are used to collectively refer to these capacitors (CM0...CM30) and switches (SW0...SW30).

Figure 4 shows an equivalent circuit in a state where switches 423 and 425 shown in Figure 3 are connected to terminal Ta (active period), and switches 423 and 425 are omitted from the illustration.

The capacitor CM0 and the switch SW0, the capacitor CM1 and the switch SW1, ... the capacitor CM10 and the switch SW10 in the measurement capacitance unit 424 are connected in series. The eleven sets of the capacitors CM and the switches SW connected in series are connected in parallel between the potential of the drive voltage AVCC (for example, the drive voltage AVCC2) and the negative input terminal of the comparator 421.
Therefore, by turning on/off the switches SW0 to SW10, it is possible to change the capacitance value of the measurement capacitance section 424 that affects the received signal R-. The on/off of each switch SW in the measurement capacitance section 424 is controlled by the bit signal BS.
Each of the switches SW0 to SW10 is configured using a switch element such as a field effect transistor (FET), but a plurality of switch elements may be provided as one switch SW.

The capacitor CM20 and the switch SW20, the capacitor CM21 and the switch SW21, the capacitor CM30 and the switch SW30 in the reference capacitance section 422 are also connected in series. The eleven sets of the capacitors CM and the switches SW connected in series are connected in parallel between the potential of the drive voltage AVCC (for example, the drive voltage AVCC2) and the + input terminal of the comparator 421.
Therefore, the capacitance value of the reference capacitance unit 422 can be changed by turning on/off the switches SW20 to SW30. The on/off of each switch SW in the reference capacitance unit 422 is controlled by a mode control signal SS. The switches SW20 to SW30 are also configured using switching elements such as FETs.

Here, consider an example in which, during scanning, the capacitance value of the measuring capacitance section 424 is changed in 256 steps by 8 bits of the 11-bit bit signal BS.
4, the measurement capacitance unit 424 is shown as having 11 sets of capacitors CM and switches SW, but if the capacitance value is to be changed in 256 steps, for example, eight sets are sufficient. For example, if the switches SW0 to SW7 are turned on/off in response to each bit of the bit signal BS, the capacitance value in the measurement capacitance unit 424 can be changed in 256 steps. Here, the reason for having 11 sets is that the reception sensitivity mode can be changed.

The reference capacitance section 422 can be configured with a single capacitor CM because it only needs to have a fixed capacitance value that is the median value of 256 steps, for example a capacitance value equivalent to "128." However, one of the purposes of having 11 sets, like the measurement capacitance section 424, as shown in the figure, is to allow for changing the reception sensitivity mode.

The gain settings G0, G1, G2, and G3 are indicated at the top of FIG.
At gain setting G0, capacitors CM20 to CM27 are used.
In the gain setting G1, capacitors CM21 to CM28 are used.
In gain setting G2, capacitors CM22 to CM29 are used.
In gain setting G3, capacitors CM23 to CM30 are used.

That is, by changing the gain settings G0, G1, G2, and G3, the reception signal sensitivity mode can be changed in four stages.
For example, in the gain setting G0, the reference capacitance unit 422 sets a capacitance value equivalent to "128" using the capacitors CM20 to CM27.
In reality, the mode control signal SS is assumed to be an 11-bit signal corresponding to the switches SW20 to SW30, but in the case of the gain setting G0, the mode control signal SS has a logical value that always controls the switches SW28, SW29, and SW30 to be off. Then, by setting each bit corresponding to the switches SW20 to SW27 to a predetermined value, a capacitance value equivalent to "128" is obtained using the capacitors CM20 to CM27. Note that by using eight capacitors CM, the capacitance value in the reference capacitance section 422, i.e., the capacitance value equivalent to "128", can be adjusted.

Similarly, for example, in gain setting G1, the reference capacitance unit 422 sets a capacitance value equivalent to "128" using capacitors CM21 to CM28. In gain setting G2, the reference capacitance unit 422 sets a capacitance value equivalent to "128" using capacitors CM22 to CM29, and in gain setting G3, the reference capacitance unit 422 sets a capacitance value equivalent to "128" using capacitors CM23 to CM30.

In this way, according to each gain setting that changes the reception sensitivity, the capacitor CM of the measurement capacitance section 424 is used as follows.
When the gain is set to G0, capacitors CM0 to CM7 are used.
When the gain is set to G1, capacitors CM1 to CM8 are used.
When the gain is set to G2, capacitors CM2 to CM9 are used.
When the gain is set to G3, capacitors CM3 to CM10 are used.

For example, when the gain is set to G0, the measurement capacitance section 424 changes the capacitance value in 256 steps using the capacitors CM0 to CM7.
In reality, the bit signal BS is assumed to be an 11-bit signal corresponding to the switches SW0 to SW10, but in the case of the gain setting G0, the bits in the bit signal BS corresponding to the switches SW8, SW9, and SW10 have a logical value that always controls them to be off. Then, by changing each bit corresponding to the switches SW0 to SW7, the capacitance value is varied in 256 steps using the capacitors CM0 to CM7.

The capacitance values of the capacitors in the reference capacitance section 422 and the measurement capacitance section 424 are set as follows, for example.
Capacitors CM0 and CM20 are 2 fF (femtofarads), capacitors CM1 and CM21 are 4 fF, capacitors CM2 and CM22 are 8 fF, capacitors CM3 and CM23 are 16 fF, capacitors CM4 and CM24 are 32 fF, capacitors CM5 and CM25 are 64 fF, capacitors CM6 and CM26 are 128 fF, capacitors CM7 and CM27 are 256 fF, capacitors CM8 and CM28 are 512 fF, capacitors CM9 and CM29 are 1024 fF, and capacitors CM10 and CM30 are 2048 fF.

In FIG. 4, each capacitor CM is composed of a single capacitor, but all or part of the capacitor CM may be composed of multiple capacitors, with the combined capacitance being the capacitance value described above.

For example, in the case of gain setting G0, capacitors CM0 to CM7 are selected by the values of 8 bits, from bit "0" to bit "7", of the 11 bits of the bit signal BS. Capacitor CM0 and switch SW0 function as bit "0", capacitor CM1 and switch SW1 function as bit "1", ... capacitor CM7 and switch SW7 function as bit "7".
A capacitance setting value ranging from 0 (="00000000") to 255 (="11111111") is given as this 8-bit value. The capacitance setting value is one piece of setting information that the MCU 5 writes to the interface register circuit 44.
In the receiving circuit 42, the switches SW0 to SW7 are turned on/off according to this 8-bit capacitance setting value. That is, the switches SW0 to SW7 are turned off when the corresponding bit is "0" and turned on when the corresponding bit is "1." This allows the overall capacitance value of the measuring capacitance section 424 to be varied in 256 steps within the range of 0 fF to 510 fF.

On the other hand, the capacitance value set by capacitors CM20 to CM27 of the reference capacitance section 422 on the received signal R+ side, i.e., the capacitance value corresponding to "128", is set to, for example, 256 fF.

As described above, the degree of potential rise of the waveform of the reception signal R- during the active period varies depending on the presence or absence of touch and the position of the touch, and may be larger or smaller than the degree of rise (ΔV) of the waveform of the reception signal R+.
In the configuration of Figure 4, the degree of potential rise in the waveform of the received signal R- can be changed by changing the capacitance setting value of the measurement capacitance section 424, and it is possible to find, for example, a capacitance setting value of the measurement capacitance section 424 that is equivalent to that of the received signal R+.

For example, when the waveform Sg1 shown by the dashed line of the received signal R- in Fig. 4 is in the initial state, if the capacitance of the measurement capacitance part 424 is reduced, the received signal R- will become smaller than the waveform Sg1 as shown in waveform Sg2. On the other hand, if the capacitance of the measurement capacitance part 424 is increased, the received signal R- will become larger than the waveform Sg1 as shown in waveform Sg3.
In other words, when the voltage levels of the receiving signals R+ and R− in the comparator 421 become equal, the capacitance setting value of the measuring capacitance section 424 becomes equivalent to a value corresponding to a voltage change of the receiving signal R− due to a touch.

Therefore, the capacitance setting value of the measurement capacitance unit 424 is changed sequentially while monitoring the output of the comparator 421, and a capacitance setting value is searched for where the voltages during the active period of the received signals R+ and R- are equivalent. The capacitance setting value thus found can then be used as the RAW value that serves as sensing information for the touch operation.

The above has been explained using an example of gain setting G0, but the method of detecting the RAW value can be considered similarly for other gain settings. In other words, the eight capacitors CM used to set the capacitance value equivalent to "128" in the reference capacitance section 422 and the eight capacitors CM used to change the capacitance value in 256 steps in the measurement capacitance section 424 are different for each gain setting as described above.

Regarding the gain settings, the sensitivity of touch signal detection can be increased by selecting the gain settings G3, G2, G1, and G0 in this order. Specifically, the capacitance value of the capacitor CM selected by selecting the gain settings G3, G2, G1, and G0 in this order becomes smaller, so that the voltage per resolution can be detected finely. This makes it possible to amplify and detect smaller changes in capacitance (voltage) as larger changes in the RAW value. For example, in the example of Figure 4, when the gain setting is switched one step to the high sensitivity side, the change in the RAW value can be amplified and detected twice as much.

In the above configuration, this embodiment enables accurate touch detection for both finger touch and glove touch. This is achieved by automatically switching the reception sensitivity mode to the optimal state based on the gain setting.

The touch signal strength differs between finger touch, where the user touches directly with a finger, and glove touch, where the user touches while wearing a glove. The touch signal strength may also differ depending on the type of glove, for example, whether the glove is made of cloth or leather. For this reason, the appropriate sensitivity (gain setting) differs depending on whether the glove is touched with a finger or a gloved hand.

Therefore, in this embodiment, it is possible to select a normal sensitivity gain setting mode (called "normal mode") and a high sensitivity gain setting mode (called "high sensitivity mode") depending on the signal strength during touch operation.

In the first sensing of this embodiment, touch position coordinates can be obtained with a resolution finer than the cell size.

Each of the squares in FIGS. 5A, 5B, and 5C indicates the above-mentioned cell, that is, a set of two transmission signal lines (Y electrodes 21) and two reception signal lines (X electrodes 22).
A block BK is made up of 16 cells (4x4), and the raw values of each cell in the block BK are represented by "a" to "p" as shown in Fig. 5D. These "a" to "p" are the raw values obtained when each cell is scanned. For example, in the block BK in Fig. 5A, "a" is the raw value of the shaded cell.

In the receiving circuit 42, scanning is performed for each cell to detect the RAW value with a resolution of 256 steps as described above, and the MCU 5 obtains the touch position coordinates from the RAW value of each cell.
In this case, the selection of 16 cells for this block BK is switched in sequence as shown in FIG. 5A, FIG. 5B, and FIG. 5C, and the pattern of the raw values is determined.

FIG. 6 shows a certain cell and touch positions on that cell as "A", "B", "C" and "D".
When the touch position is "A", the RAW value of pattern A in Fig. 7 is obtained in a block BK of 16 cells including the cell in question. "+" indicates that the RAW value is greater than 128, and "-" indicates that the RAW value is less than 128. Note that "128" means that the RAW value is close to 128. This is because the RAW value of a cell with no capacitance change is not always strictly "128", but fluctuates slightly.
7. Similarly, when the touch position is "B", "C", or "D" in FIG. 6, the RAW value pattern in the block BK including the cell in question will be pattern B, pattern C, or pattern D in FIG.
By detecting such a pattern, the MCU 5 can obtain touch position coordinates with a resolution finer than the cell size.

2. First sensing and second sensing
The difference between the first sensing and the second sensing will be described below. The first sensing and the second sensing have different scanning methods for the X electrodes 22 and the Y electrodes 21.
The first sensing scan has been mentioned above, and is shown diagrammatically in FIG.

In FIG. 8, solid lines indicate the Y electrodes 21 and X electrodes 22 that are being selected in scanning, and dashed lines indicate the Y electrodes 21 and X electrodes 22 that are not selected.
At a certain point in time, a pair of Y electrodes 21-1 and 21-2, which are transmission signal lines, and a pair of X electrodes 22-1 and 22-2, which are reception signal lines, are selected as shown in the figure. In this state, the idle period and active period are processed as described in Figures 3 and 4, and the RAW value is detected.

At the next timing, the transmission signal lines are set to the Y electrodes 21-2 and 21-3, and the RAW value is detected.
At the next timing, the transmission signal lines are set to the Y electrodes 21-3 and 21-4, and the RAW value is detected.
Thereafter, the sets of transmission signal lines are switched until the Y electrodes 21-(n-1) and 21-n (see FIG. 2) are selected and the RAW value is detected.

At the next timing, the transmission signal lines are returned to the Y electrodes 21-1 and 21-2, while the reception signal lines are switched to the X electrodes 22-2 and 22-3. In this state, the RAW value is detected.
At the next timing, the transmission signal lines are switched to the Y electrodes 21-2 and 21-3, and the RAW value is detected. That is, the pairs of transmission signal lines are switched in sequence until the Y electrodes 21-(n-1) and 21-n are selected and the RAW value is detected.

The above switching is performed when the receiving signal line is in the state of X electrodes 22-(m-1) and 22-m and the transmitting signal line is in the state of Y electrodes 21-1, 21-2 to the set of Y electrodes 21-(n-1) and 21-n.

The above is the scanning of one frame.
In this way, the two transmitting signal lines and the two receiving signal lines are sequentially shifted and scanned, so that in one frame, RAW values whose number is the product of the number of sets of X electrodes 22 and the number of sets of Y electrodes 21 are detected.

9A and 9B are schematic diagrams showing the second sensing operation.
In FIG. 9A, all the Y electrodes 21 are shown by solid lines, which indicates a state in which the transmission signal T+ is applied to all the Y electrodes 21.

In this state, the pair of X electrodes 22-1 and 22-2 is selected as a reception signal line, and one RAW value detection is performed through the operations described with reference to FIGS.
At the next timing, the pair of X electrodes 22-2 and 22-3 is selected as the reception signal line, and one detection of the RAW value is performed.
This is switched until a set of X electrodes 22-(m-1), 22-m is selected.

Next, as shown in FIG. 9B, all of the X electrodes 22 are shown with solid lines, which indicates a state in which the transmission signal T+ is applied to all of the X electrodes 22.
That is, the state in which the Y electrodes 21 are used as transmission signal lines as shown in FIG. 9A is switched to a state in which the X electrodes 22 are used as transmission signal lines.
Such switching can be achieved by a multiplexer 43 (see FIG. 2) switching the connections of the transmission circuit 41 and the reception circuit 42 to the Y electrodes 21 and the X electrodes 22 .

In this state, the pair of Y electrodes 21-1 and 21-2 is selected as a reception signal line, and one RAW value detection is performed through the operations described with reference to FIGS.
At the next timing, the pair of Y electrodes 21-2 and 21-3 is selected as the reception signal line, and one detection of the RAW value is performed.
This switching is continued until the pair of Y electrodes 21-(n-1), 21-n is selected.

This completes the scanning of one frame.
In this manner, the two reception signal lines are sequentially shifted and scanned, so that the number of RAW values detected in one frame is the sum of the number of sets of X electrodes 22 and the number of sets of Y electrodes 21 .
Therefore, the second sensing can perform one frame scan in a shorter time than the first sensing.

In the case of the second sensing, the transmission signals T+ and T- are not provided to a pair of transmission signal lines, but the transmission signal T+ is provided to all of the transmission signal lines.
Also, instead of reversing the signal level as in the idle period and active period shown in Fig. 3, the transmission signal T+ continues to be at H level during the sensing period for detecting the RAW value as shown in Fig. 9C. The transmission signal T+ only goes to L level at the timing of switching the reception signal line.

This second sensing is a so-called self-capacitance method, and the receiving circuit 42 detects the RAW value from the change in capacitance between the receiving signal line and ground. Even if water droplets adhere to the receiving signal line, there is no change in the capacitance between the receiving signal line and ground unless the water droplets are very small and connected to the ground.
On the other hand, if you touch it with your finger, the human body is connected to ground, so a change occurs in the capacitance between the receiving signal line and ground. Therefore, the case of touching it with a finger can be distinguished from the case of water droplets adhering to it.

In contrast, the first sensing method is a mutual capacitance method, which detects a change in capacitance between a transmission signal line and a reception signal line.
In other words, the first sensing is a method in which the signal waveforms of the two transmitting signal lines (Y electrodes 21) are reversed in logic, and scanning is performed by switching them to L level and H level waveforms during the idle period and to H level and L level waveforms during the active period, and the difference in the receiving signal lines from the idle period to the active period is taken to detect the RAW value as the amount of signal change.
In this case, if water droplets adhere to the sensor, the capacitance will increase due to the water droplets, causing a change in the detected value. Also, if a finger is touched to the sensor, the finger will decrease the capacitance, causing a change in the detected value.

Between the first sensing and the second sensing, the second sensing can increase the sensing speed per frame, but the first sensing has a higher touch detection accuracy.
This is because in the case of the second sensing, due to the above-mentioned scanning method, when multiple points are touched on the touch panel surface, it may not be possible to narrow down the coordinates completely.
FIG. 10 illustrates X coordinate values (X0, X1, X2, X3) by the X electrodes 22 and Y coordinate values (Y0, Y1, Y2, Y3) by the Y electrodes 21.
In this case, suppose that a finger touches two points at coordinates (X2, Y0) and (X1, Y3) as shown in the figure. As a result of the touch detection, X1 and X2 are detected as X coordinate values, and Y0 and Y3 are detected as Y coordinate values. As a result, the four points shown in the figure are estimated as the touch positions.

On the other hand, in the case of the first sensing, as shown in FIG. 11, two points with coordinates (X2, Y0) and (X1, Y3) are correctly detected as contact positions as a touch detection result. Therefore, in the above-mentioned normal mode and high sensitivity mode, it is desirable to use the first sensing.

<3. Processing example>
A specific example of processing using the above first sensing and second sensing will be described.
As mentioned above, the normal mode and high sensitivity mode in the first sensing are automatically selected during sensing to detect the touch position, thereby enabling appropriate detection of the touch position whether it is a finger touch or a glove touch.

To this end, it is conceivable to provide a threshold value for the touch signal strength, and select the normal mode when the touch signal strength is equal to or greater than the threshold value, and the high sensitivity mode when the touch signal strength is less than the threshold value.
For example, prior to scanning for actual touch detection, scanning is performed in the high sensitivity mode of the first sensing, and the touch signal strength at that time is detected to select the mode.

However, when a large amount of water adheres to the touch panel 2, the large amount of water may be erroneously recognized as a finger touch. This is because the signal strength at the moment when a large amount of water adheres to the touch panel 2 is very similar to the signal strength in the case of a finger touch.
Furthermore, if a finger touch is mistakenly recognized and normal mode is selected, the signal strength due to water may exceed the threshold for finger touch determination in normal mode, causing a touch reaction, which may result in a false reaction or malfunction.

Therefore, in this embodiment, the second sensing is used for the scan for mode determination, so that even if there is a small amount of water (water droplets, etc.), no touch reaction occurs.
However, there is still a possibility of erroneous judgment if the device is splashed with a large amount of water, is under running water, or is touched over such water. This is for the following reasons.
During the second sensing scan, the non-selected receiving signal lines are set to ground potential. When a large amount of water adheres to a receiving signal line, the water strengthens the capacitive coupling with the adjacent receiving signal lines (ground potential). This results in a large change in the capacitance of the cell in the area where a large amount of water adheres. This can result in a touch-like reaction due to the adhesion of a large amount of water.
Therefore, an evaluation value corresponding to the signal strength in the second sensing is calculated, and the evaluation value and the rate of increase (slope) are used to distinguish between a large amount of water or a finger.

The evaluation value according to the signal strength is the sum of the squares of the individual RAW values (amount of change in capacitance) detected in the second sensing.
For example, since the number of RAW values obtained by scanning one frame is the sum of the number of sets of X electrodes 22 and the number of sets of Y electrodes 21, the sum is calculated by squaring each RAW value. The reason for squaring is to capture the amount of change as an absolute value.

Figure 12 shows the change in evaluation value for normal finger touch, and Figure 13 shows the change in evaluation value when a large amount of water is splashed. The vertical axis of Figures 12 and 13 is the evaluation value, and the horizontal axis is the scan frame, and the change in evaluation value for each scan of one frame is shown in time series.

When there is a finger touch as shown in Fig. 12, the evaluation value rises relatively steeply. On the other hand, when a large amount of water is splashed as shown in Fig. 13, the rate at which the evaluation value rises is much slower than when there is a finger touch. This is thought to be because when water adheres to the touch panel 2, the area of the water is small, but then the water flows and the area gradually expands, so the evaluation value also rises gradually.
Therefore, by comparing the gradient of the increase in the evaluation value as indicated by the dashed arrow with a threshold value, it is possible to distinguish between a finger touch and a large amount of water.

The determination of whether the touch is a finger touch or water based on the inclination can be made, for example, by calculating the moving average of the evaluation values for the past several frames for each scan frame and checking whether the difference between the moving average value at the previous frame and the current moving average value is equal to or greater than a threshold value.

A specific example of processing by the MCU 5 in the touch panel driving device 3 is shown in FIG.
Fig. 14 shows an example of processing executed by the functions of the determination control unit 5a and the detection and calculation unit 5b in the MCU 5. The processing in Fig. 14 is repeated until the operation detection by the touch panel 2 is terminated (for example, the power is turned off).

In step S101, the MCU 5 performs scan control as second sensing to determine the mode. That is, the MCU 5 instructs the transmission circuit 41 and the reception circuit 42 to perform second sensing and execute scanning. This executes second sensing, and the MCU 5 obtains the RAW value of each cell in the current frame as a result of the scanning.

The MCU 5 calculates an evaluation value based on the RAW value in this case, and if a significant value is obtained, it can be determined that a touch operation or the influence of a large amount of water has occurred.
In addition, the second sensing in step S101 is performed for one frame by scanning Fig. 9A and Fig. 9B, but for example, only the scanning in Fig. 9A or only the scanning in Fig. 9B may be performed as the second sensing for one frame, since the purpose is not to detect the coordinates of the touch position.

If a significant RAW value indicating the possibility of an operation is not obtained in the second sensing in step S101, it is determined that a touch operation has not been performed, and the MCU 5 returns from step S102 to step S101 and scans the next frame.
In addition to when no touch operation is performed, if there are slight water droplets on the touch panel due to the second sensing, no significant RAW value is detected and the process returns to step S101.

In the case of a finger touch, a glove touch, or a large amount of water being splashed, a significant RAW value to some extent is detected by the second sensing in step S101. In that case, the MCU 5 proceeds from step S102 to step S103, and determines whether the evaluation value for the current frame exceeds the threshold value th1.
The threshold value th1 is set as a value for determining whether a touch is a finger touch or a glove touch.

If the evaluation value is equal to or less than the threshold value th1, the MCU 5 determines that a glove touch has occurred, proceeds to step S107, selects the high sensitivity mode, and performs scanning control to determine the actual touch position. That is, the MCU 5 causes the transmission circuit 41 and the reception circuit 42 to perform scanning in the high sensitivity mode of the first sensing. In response to this, the reception circuit 42 scans each cell, for example, in a mode with a gain setting of G0. As a result of this scanning, the MCU 5 obtains the RAW value of each cell.

Then, in step S111, MCU5 uses the acquired RAW values of each cell to perform pattern detection of the sensed cells (see FIG. 7), and in step S112 performs coordinate calculation processing based on the pattern to identify the touch position, and in step S113 outputs a coordinate report to the product-side MCU 90.

If the evaluation value exceeds the threshold value th1 in step S103, the MCU 5 proceeds to step S104. In this case, there is a possibility that a signal has been detected as a significant RAW value due to the influence of a finger touch or a large amount of water. Therefore, the MCU 5 judges the magnitude of the gradient of the evaluation value. For example, as described above, it judges whether the difference in the moving average values is equal to or greater than a predetermined threshold value. This threshold value is a value set to distinguish between the difference in gradients as shown in Figures 12 and 13.

If the inclination is determined to be large, the MCU 5 determines that it is a finger touch and proceeds to step S105, where it selects normal mode and performs scanning control to determine the actual touch position. That is, the MCU 5 causes the transmission circuit 41 and reception circuit 42 to perform scanning in the normal mode of the first sensing. In response to this, the reception circuit 42 scans each cell, for example, in gain setting G2 mode. As a result of this scanning, the MCU 5 obtains the RAW value of each cell.

Then, in step S108, the MCU5 uses the acquired RAW values of each cell to perform pattern detection for the sensed cells, and in step S112 performs coordinate calculation processing based on the pattern to identify the touch position, and in step S113, outputs a coordinate report to the product-side MCU 90.

If it is determined in step S104 that the inclination is small, the MCU 5 determines that there has been an effect of a large amount of water. In this case, there are cases where the user has performed a touch operation on a panel surface with a large amount of water attached thereto, and cases where a certain level of signal strength has been detected even when no touch operation has been performed.
Therefore, the MCU 5 proceeds to step S106, selects the water mode, and performs scanning control for determining the touch position. That is, the MCU 5 causes the transmission circuit 41 and the reception circuit 42 to execute scanning by the second sensing. As a result, the second sensing is executed, and the MCU 5 obtains the RAW value of each cell of the current frame as a result of the scanning.

Note that the second sensing in water mode in step S106 is performed for one frame by scanning in Figs. 9A and 9B. This is to detect the coordinates of the touch position.

In the second sensing, water droplets do not or only slightly change the capacitance between the receiving signal line and ground, but if the user actually touches the device even when there is water on it, or if a large amount of water causes a connection with the ground via the receiving signal line and strengthens the capacitive coupling, a relatively large change in capacitance is detected.
Therefore, when a RAW value corresponding to a touch operation is detected by a change in capacitance in the second sensing, the MCU 5 performs pattern detection of the sensed cell in step S109.

In water mode, the RAW value pattern acquired in the second sensing distinguishes between touch operation and the influence of a large amount of water. In the case of touch operation, a RAW value (+) greater than "128" and a RAW value (-) less than "128" are detected adjacent to each other. For example, the pattern is "+", "+", "-", "-" in adjacent cells.
On the other hand, in the case of a large amount of water, the RAW value of "128" is placed between RAW values (+) greater than "128" and RAW values (-) less than "128." For example, the pattern would be "+", "128", "-", "-" in adjacent cells.
The MCU 5 judges whether it is a touch or a large amount of water based on the difference in these patterns.

If a pattern representing a touch operation is detected, the MCU 5 proceeds from step S110 to step S112 assuming that an actual touch operation has occurred, and performs coordinate calculation processing to identify the touch position. Then, in step S113, the MCU 5 outputs a coordinate report to the product-side MCU 90.

On the other hand, if the pattern of the cell in which the capacitance change was detected is determined to be a large amount of water, it is determined to be affected by a large amount of water, and the process returns from step S110 to step S101. In other words, coordinate calculation processing and coordinate report processing are not performed. This prevents erroneous detection.

Through the above processing, the MCU 5 selects the appropriate mode between normal mode and high sensitivity mode depending on the signal strength of the evaluation value obtained by the second sensing, and further performs scanning control to select between normal mode and water mode depending on the slope of the evaluation value.

4. Effects and Modifications of the Embodiments
According to the sensing method performed in the touch panel device 1 and the touch panel drive device 3 described in the above embodiment, the following effects can be obtained.

In the embodiment, a touch panel driving device 3 capable of performing a first sensing for the touch panel 2, which sequentially selects a pair of adjacent transmission signal lines and a pair of adjacent reception signal lines and performs scanning to detect the amount of change in capacitance during the stabilization period and the sensing period, and a second sensing for performing scanning in which the selection state of the transmission signal lines and the reception signal lines is different from that in the first sensing and detects the change in capacitance between the reception signal lines and ground during the sensing period, is shown. The touch panel driving device 3 then performs a determination procedure (steps S101 to S104 in FIG. 14) in which the second sensing is performed, an evaluation value according to the signal strength of the obtained detection signal is obtained, and whether or not the detection signal is due to the influence of water is determined based on the change in the evaluation value over time, and a first calculation procedure (steps S105, S108, S112, S113) in which the first sensing is performed, and a coordinate calculation is performed based on the obtained detection signal to output detection information.

By being able to distinguish between finger touch and the influence of water based on the change in the evaluation value over time, it is possible to prevent false detections even when a large amount of water adheres to the touch panel 2, thereby improving the detection performance of the touch panel.

In other words, by distinguishing between finger touch and the influence of a large amount of water or running water based on the change in the evaluation value over time, the accuracy of determining the sensing mode to be executed is improved. This makes it possible to set the sensor to normal mode except when it is exposed to running water or a large amount of water, thereby preventing erroneous responses.
Furthermore, by using the second sensing for such mode determination, it is possible to reduce the time required for state detection and mode determination and the amount of processed data.

In the second sensing of the embodiment, while all of the transmitting signal lines and the receiving signal lines are selected, a pair of adjacent signal lines is sequentially selected for the other signal line, and the evaluation value is a value equivalent to the sum of the absolute values of the amount of change in each detection signal obtained in the second sensing. As an example, the evaluation value is the sum of the squares of the amount of change in each detection signal obtained in the second sensing.
With this type of second sensing, the change in detection of water droplets is small, and the change in detection of finger touch is large. Therefore, in one frame of scanning, an evaluation value equivalent to signal strength is calculated as the sum of the absolute values of signal changes in the + and - directions.
The touch operation and the influence of water can be determined based on the change in this evaluation value over time.

In the embodiment, if the determination procedure determines that the detection signal is due to the influence of water, the second sensing is performed in the water mode. Then, it is determined whether the obtained detection signal is due to a touch operation, and if it is determined that the detection signal is due to a touch operation, a coordinate calculation is performed based on the obtained detection signal and detection information is output, and if it is determined that the detection signal is not due to a touch operation, a second calculation procedure (steps S106, S109, S110, S112, and S113) is performed in which the coordinate calculation and the detection information are not output.
Even when the device is affected by a large amount of water, there are cases where there is only water and cases where a finger touch is performed on top of water. In this case, the second sensing is performed. Since the second sensing has a small change in detection due to water and a large change in detection due to finger touch, the position (coordinates) of the finger can be accurately identified even in a wet environment when a touch operation is performed. Furthermore, when it is determined that the device is affected by a large amount of water, unnecessary processing can be avoided by not performing coordinate calculations and outputting detection information, and false detection due to water can be avoided.

In the embodiment, the touch panel driving device 3 allows the signal detection sensitivity setting for the first sensing to be selected between a normal mode and a high sensitivity mode with a higher sensitivity, and in the judgment procedure, it is also determined whether or not the state is low sensitivity based on the signal strength of the detection signal obtained in the second sensing, and in the first calculation procedure, the first sensing is performed in the normal mode, and if the judgment procedure determines that the state is low sensitivity, the first sensing is performed in the high sensitivity mode, and a third calculation procedure (steps S107, S111, S112, S113) is further performed in which coordinate calculation is performed based on the obtained detection signal and detection information is output.
This makes it possible to perform touch detection with high accuracy, even with gloved touch.
Furthermore, by determining the condition using both the rise rate and strength of the signal in the second sensing, it is possible to distinguish between four states: finger, glove, water droplet, and large amount of water.

In the touch panel device 1 of the embodiment, a touch operation is performed by actually touching the panel surface. However, the present invention also includes touch panel devices that support so-called hover sensing (non-contact proximity operation), which performs an operation equivalent to touch, and in this case, the same sensing method as described above can be applied. In other words, "touch" in the present invention and the embodiment also includes a non-contact proximity operation state.

1 Touch panel device 2 Touch panel 3 Touch panel driving device 4 Sensor IC
5. MCU
5a: Determination control unit 5b: Detection calculation unit 5M: Memory 21: Y electrode 22: X electrode 41: Transmission circuit 42: Reception circuit 43: Multiplexer 44: Interface register circuit,

Claims (6)

A sensing method for a touch panel drive device capable of performing a first sensing for a touch panel, the first sensing being for sequentially selecting a pair of adjacent transmission signal lines and a pair of adjacent reception signal lines and scanning the touch panel to detect a change in capacitance between a stabilization period and a sensing period, and a second sensing being for performing a second sensing in which a selection state of the transmission signal lines and the reception signal lines is different from that of the first sensing and a change in capacitance between the reception signal lines and ground during the sensing period is detected,
a determination step of performing the second sensing, obtaining an evaluation value according to a signal strength of the obtained detection signal, and determining whether or not the detection signal is due to the influence of water based on a change in the evaluation value over time;
a first calculation step of performing the first sensing when it is determined that the detection signal is not due to the influence of water, and then performing a coordinate calculation based on the obtained detection signal to output detection information. the second sensing is a scanning in which, while all of one of the transmission signal lines and the reception signal lines are selected, a pair of adjacent signal lines is selected in sequence for the other;
The sensing method according to claim 1 , wherein the evaluation value is a value equivalent to a sum of absolute values of amounts of change of the individual detection signals obtained in the second sensing. 3. The sensing method according to claim 2, wherein if it is determined in the determination procedure that the detection signal is due to the influence of water, the second sensing is performed to determine whether the obtained detection signal is due to a touch operation, and if it is determined that the detection signal is due to a touch operation, a coordinate calculation is performed based on the obtained detection signal and detection information is output, and if it is determined that the detection signal is not due to a touch operation, a second calculation procedure is performed in which no coordinate calculation and no output of detection information is performed. the touch panel drive device is configured such that, for the first sensing, a signal detection sensitivity setting can be selected between a normal mode and a high sensitivity mode having a higher sensitivity than the normal mode;
In the determination step, a determination is also made as to whether or not the state is in a low sensitivity state based on a signal strength of the detection signal obtained in the second sensing step;
In the first calculation step, the first sensing is performed in the normal mode;
The sensing method according to claim 1 or claim 3, wherein if the judgment procedure determines that the state is a low sensitivity state, the first sensing is performed in the high sensitivity mode, and a third calculation procedure is performed in which a coordinate calculation is performed based on the obtained detection signal to output detection information. A touch panel drive device capable of executing a first sensing for a touch panel, the first sensing comprising a scanning step of sequentially selecting a pair of adjacent transmission signal lines and a pair of adjacent reception signal lines and detecting a change in capacitance between a stabilization period and a sensing period, and a second sensing step of scanning a selection state of the transmission signal lines and the reception signal lines that is different from that of the first sensing step and detecting a change in capacitance between the reception signal lines and ground during the sensing period, the touch panel drive device comprising:
a control device that performs the second sensing, calculates an evaluation value according to the signal strength of the obtained detection signal, and determines whether or not the detection signal is due to the influence of water based on a change in the evaluation value over time; and when it is determined that the detection signal is not due to the influence of water, performs the first sensing, performs coordinate calculations based on the obtained detection signal, and outputs detection information. A touch panel and
a touch panel drive device capable of executing a first sensing for the touch panel, the first sensing being for sequentially selecting a pair of adjacent transmission signal lines and a pair of adjacent reception signal lines and scanning the touch panel to detect a change in capacitance between a stabilization period and a sensing period, and a second sensing being for performing a second sensing in which a selection state of the transmission signal lines and the reception signal lines is different from that of the first sensing and a change in capacitance between the reception signal lines and ground during the sensing period is detected;
The touch panel drive device is
a control device that performs the second sensing, calculates an evaluation value according to the signal strength of the obtained detection signal, and determines whether or not the detection signal is due to the influence of water based on a change in the evaluation value over time; and when it is determined that the detection signal is not due to the influence of water, performs the first sensing, performs coordinate calculations based on the obtained detection signal, and outputs detection information.

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