JP7283662B2 - Touch panel device and touch panel device control method - Google Patents

Description

The present invention relates to a touch panel device that detects external noise in a mutual-capacitance touch panel and counteracts the noise.

2. Description of the Related Art In recent years, touch panels have been widely used as input means for user operations not only in electronic devices such as mobile terminals and PDAs (Personal Digital Assistants), but also in street advertisements and operation panels of industrial products. In particular, a touch panel having a detection principle of the electrostatic capacitance method, which is mainly based on the mutual capacitance method, is used in many applications compared to other methods.

A mutual capacitance touch panel identifies touch coordinates from a characteristic pattern of a signal input from a sensor. Here, when noise is superimposed on the input from the sensor, the characteristic pattern of the signal is disturbed or formed. As a result, an error is caused in the operation based on the input from the touch panel.

As a conventional technology, there is known a mutual capacitance touch panel provided with a process to counteract the above noise. For example, Patent Literature 1 discloses a technique for reducing the influence of noise by determining the presence or absence of noise in a sensor input in a touch panel and changing the transmission frequency to avoid the frequency of the noise.

Japanese Patent No. 5814707

However, the method described in Patent Document 1 has a problem that it is difficult to detect the presence or absence of noise itself in a situation where it is difficult to discriminate noise from sensor input (for example, in an environment where noise is extremely strong). .

One aspect of the present invention has been made in view of the above problems, and an object of the present invention is to provide a touch panel device that can easily determine the presence or absence of external noise without using complicated filter technology. That's what it is.

A touch panel device according to an aspect of the present invention is a mutual capacitance touch panel including a plurality of transmission electrodes and a plurality of reception electrodes that form capacitive coupling, and a driving voltage is applied to the plurality of transmission electrodes. a driving unit for measuring outputs from the plurality of receiving electrodes; and a measurement value obtained by the measuring unit when the driving voltage is applied to the plurality of transmitting electrodes to determine touch coordinates. A coordinate specifying unit for specifying, and a noise detecting unit for detecting noise using the measurement values of the measuring unit obtained when the driving voltage is not applied to the plurality of transmitting electrodes.

According to the above configuration, the signals obtained at the plurality of reception electrodes when the drive voltage is not applied to the plurality of transmission electrodes are signals derived from noise. Therefore, with the above configuration, it is possible to easily determine the presence or absence of noise without using a complicated noise filter technique.

Further, the drive section includes a plurality of output terminals for outputting the drive voltage, and among the plurality of output terminals, at least one output terminal is not connected to the plurality of transmission electrodes, and the other plurality of output terminals are not connected to the plurality of transmission electrodes. An output terminal may be connected to the plurality of transmission electrodes.

According to the above configuration, for example, the control section does not need to instruct the drive section not to apply the drive voltage to any of the transmission electrodes. For example, the drive section may sequentially output the drive voltage to a plurality of output terminals upon receiving an instruction to start outputting the drive voltage from the control section. Therefore, the circuit in the driving section does not need to have a special configuration, and at least one output terminal may not be connected to the transmission electrode. Therefore, the touch panel device can simplify the control method of the control unit.

Further, the touch panel device determines the frequency, phase, and/or duty ratio of the drive voltage according to the detected noise, and instructs the drive unit to provide the determined frequency, phase, and / Or the structure may be provided with a controller that designates a duty ratio and instructs to apply the drive voltage to the plurality of transmission electrodes.

According to the above configuration, the presence or absence of noise can be determined without using complicated filter technology. Further, the touch panel device applies frequency hopping (by changing the frequency, phase, and/or duty ratio of the driving voltage) according to the presence or absence of noise, thereby reducing the influence of noise and adjusting the touch coordinates. can be identified.

Further, the touch panel device includes a noise filter unit that performs processing to reduce the influence of noise on the measured value of the measuring unit, and according to the noise, the measured value of the measuring unit The configuration may include a control unit that determines whether or not to perform processing for reducing the influence of noise.

According to the above configuration, it is possible to specify the touch coordinates while reducing the influence of noise. Moreover, when there is no noise or the noise is small, filtering is not performed, so the processing load of filtering can be reduced. As a result, for example, the touch panel device can increase the number of times of identifying touch coordinates per time (shorten the cycle of identifying processing of touch coordinates) when there is no or little noise.

Further, the touch panel device selects a noise filter unit that performs processing to reduce the influence of noise on the measured value of the measurement unit, and a noise filter used by the noise filter unit according to the noise. It may be a configuration including a control unit for performing.

According to the above configuration, it is possible to specify the touch coordinates while reducing the influence of noise. In addition, the noise filter can be appropriately selected according to noise information (noise presence, magnitude, and/or fluctuation).

Further, the touch panel device includes a noise filter unit that performs processing to reduce the influence of noise on the measured value of the measurement unit, and a noise filter strength used by the noise filter unit that is adjusted according to the noise. A configuration including a changing control unit may be used.

According to the above configuration, it is possible to specify the touch coordinates while reducing the influence of noise. Also, when the magnitude of noise or fluctuation is large, the noise can be reduced by increasing the strength of the noise filter.

Further, the noise detection unit identifies the magnitude of the noise at a plurality of timings, and the control unit identifies the frequency characteristic of the noise from the magnitude of the noise and the measurement interval of the noise. may

According to the above configuration, more appropriate frequency hopping can be performed based on the frequency characteristics of noise. Alternatively, the control section can select the type, combination, and/or strength of noise filters suitable for an assumed noise source corresponding to the frequency characteristics of noise.

A control method for a touch panel device according to an aspect of the present invention includes a driving step of applying a driving voltage to the plurality of transmitting electrodes; a measuring step of measuring outputs from the plurality of receiving electrodes; a coordinate specifying step of specifying touch coordinates using the measured values of the output obtained when the driving voltage is applied to the transmission electrodes; and a noise detection step of detecting noise using the measured output.

According to one aspect of the present invention, it is possible to easily determine the presence or absence of external noise without using complicated noise filter technology.

1 is a block diagram showing the configuration of a touch panel device according to Embodiment 1 of the present invention; FIG. FIG. 3 is a diagram showing a schematic cross-section of the touch panel according to the embodiment, and a relationship between drive voltage, received current, and noise waveforms; FIG. 4 is a diagram showing a schematic cross section of the touch panel when the front cover is touched with a finger, and a relationship between the drive voltage and the received current according to the embodiment; 4 is a flowchart showing an operation example of the touch panel device according to Embodiment 1 of the present invention; FIG. 4 is a block diagram showing the configuration of a touch panel device according to Embodiment 2 of the present invention; 9 is a flowchart showing an operation example of the touch panel device according to Embodiment 2 of the present invention; It is a block diagram which shows the structure of the touch-panel apparatus based on the modification of Embodiment 1 of this invention. 9 is a flowchart showing an operation example of the touch panel device according to the modification of Embodiment 1 of the present invention; It is a block diagram which shows the structure of the touch-panel apparatus based on the modification of Embodiment 2 of this invention. 10 is a flow chart showing an operation example of the touch panel device according to the modified example of the second embodiment of the present invention;

[Embodiment 1]
(Configuration example)
FIG. 1 is a block diagram showing the configuration of a touch panel device 20 according to this embodiment. The touch panel device 20 includes a touch panel 1 , a drive section 4 , a measurement section 5 , a noise detection section 6 , a control section 7 and a coordinate calculation section 8 . The touch panel device 20 according to the present embodiment is a device that performs frequency hopping based on noise-derived signals appearing on the plurality of reception electrodes 3 during a period in which signals are not transmitted from the plurality of transmission electrodes 2 .

The touch panel 1 is a mutual capacitance type touch panel. The touch panel 1 includes a plurality of transmission electrodes 2 provided along an arbitrary axis (X-axis) direction, and a plurality of reception electrodes 3 provided along an axis (Y-axis) direction perpendicular to the above-mentioned axis direction. Prepare. Each transmitting electrode 2 overlaps and intersects a plurality of receiving electrodes 3 . The transmitting electrode 2 and the receiving electrode 3 have an electrode structure called a diamond pattern.

FIG. 2 is a diagram showing a schematic cross section of the touch panel 1 and the relationship between the driving voltage and the received current. The touch panel 1 has a substrate 11 . Substrate 11 may comprise, for example, a liquid crystal display substrate. Hereinafter, in the touch panel 1, the substrate 11 side is referred to as the bottom, and the front cover 13 side is referred to as the top. A plurality of transmission electrodes 2 are formed on the substrate 11 . An insulating layer 12 is formed on the transmitting electrode 2 . A plurality of receiving electrodes 3 are formed on the insulating layer 12 . A front cover 13 is formed on the plurality of receiving electrodes 3 so as to come into contact with a finger when the user operates the touch panel 1 . It should be noted that even if the positions of the transmitting electrode 2 and the receiving electrode 3 are interchanged, there is no difference in the principle of operation.

The transmission electrodes 2 are composed of n electrodes numbered from transmission electrode 2-1 to transmission electrode 2-n. The transmitting electrode 2 forms capacitive coupling with each of the plurality of receiving electrodes 3 . The transmitting electrode 2 and the receiving electrode 3 are made of, for example, an ITO (indium tin oxide) film.

The drive unit 4 is a device that sequentially applies pulse voltages as drive voltages to the plurality of transmission electrodes 2 .

The measuring unit 5 measures outputs (current or voltage) from the plurality of receiving electrodes 3 . Here, the measurement unit 5 measures currents output from the plurality of receiving electrodes 3 . The measurement unit 5 outputs information indicating the measured value (measured current) to the noise detection unit 6 and the coordinate calculation unit 8 .

The noise detection section 6 detects noise from the information output by the measurement section 5 . Here, the noise detection unit 6 determines presence or absence of noise based on the information output by the measurement unit 5 . The noise detection section 6 outputs the determination result to the control section 7 .

The control unit 7 is a device that controls the operations of the drive unit 4 , the measurement unit 5 , the noise detection unit 6 and the coordinate calculation unit 8 . The control unit 7 instructs the driving unit 4 to output the driving voltage and instructs the measuring unit 5 to measure the current. The control unit 7 changes the frequency, phase, and/or duty ratio of the driving voltage output from the transmitting electrode 2 (performs frequency hopping) according to the noise determination result. The control unit 7 instructs the drive unit 4 on the frequency, phase (output start timing), and/or duty ratio of the drive voltage. For example, the control section 7 uses the start pulse signal and/or the clock signal supplied to the drive section 4 to specify the frequency, phase and/or duty ratio of the drive voltage. The control unit 7 instructs the noise detection unit 6 to determine the presence/absence of noise based on the measurement result of the measurement unit 5 during the period in which the drive voltage is not output. The control unit 7 instructs the coordinate calculation unit 8 to calculate touch coordinates.

A coordinate calculation unit 8 (coordinate identification unit) calculates touch coordinates from the information output by the measurement unit 5 . The coordinate calculation unit 8 identifies the touch coordinates touched by the user based on the capacitance change of each coordinate on the touch panel 1 .

It should be noted that the touch panel 1 can be implemented as a sensor comprising transmitting electrodes 2 and receiving electrodes 3 . The drive unit 4, the measurement unit 5, the noise detection unit 6, and the coordinate calculation unit 8 can be implemented by electric circuits as controllers. The sensor and controller are connected to each other, for example, by a flexible cable.

(Operation example)
FIG. 2 shows the relationship between the drive voltage and the received current. In the three graphs, the horizontal axis is time t and the vertical axis is voltage or current. Between the transmitting electrodes 2 and the intersecting receiving electrodes 3, the sides of the diamond pattern electrodes are adjacent to each other. Thereby, a capacitive coupling is formed between the transmitting electrode 2 and the receiving electrode 3 . When the drive unit 4 applies a square-wave pulse drive voltage to one of the transmission electrodes 2 , current flows through the reception electrodes 3 intersecting the transmission electrodes 2 via capacitive coupling. As a result, charges are induced in the receiving electrode 3 and the potential of the receiving electrode 3 changes. All transmission electrodes 2 to which no drive voltage is applied are connected to a fixed potential. As a result, all the transmission electrodes 2 to which no drive voltage is applied are grounded to alternating current.

FIG. 3 is a diagram showing a schematic cross section of the touch panel 1 and the relationship between the drive voltage and the received current when the front cover 13 is touched with a finger. In the three graphs, the horizontal axis is time t and the vertical axis is voltage or current. When the front cover 13 is touched with a finger, the lines of electric force flowing from the transmission electrode 2 to the reception electrode 3 are absorbed by the finger. As a result, the current flowing through the receiving electrode 3 corresponding to the drive voltage is reduced, and the change in the potential of the receiving electrode 3 is reduced. By detecting the amount by which this displacement has decreased, it is possible to measure the decrease in the electrostatic capacitance (mutual capacitance) between the transmitting electrode 2 and the receiving electrode 3 .

Exogenous noise input from the sensor includes, for example, noise (external noise A) coming from the space due to discharge, fluorescent light, radio waves, etc., and noise injected from the touched object (human body or touch pen) ( external noise B), and the like. These external noises do not change the mutual capacitance detected by the mutual capacitance type touch panel, but are detected by the measurement unit 5 as noise currents flowing through the receiving electrodes. Therefore, in order to extract the current value corresponding to the driving voltage from the measured value in which the current corresponding to the driving voltage (pulse voltage) and the noise current are superimposed, there is no choice but to use a filter technique.

In the prior art, noise is determined by various methods from a measured value in which a current corresponding to a drive voltage (pulse voltage) and a noise current are superimposed. Here, as mentioned above, correlation or heuristic filtering must be used to determine how noisy the obtained measurements are. Such filters have a high processing load.

The external noise A is noise superimposed on the current output from the space as the measurement result by the measurement unit via the sensor (receiving electrode). When a drive voltage is applied to the transmission electrodes, external noise is superimposed on the current corresponding to the drive voltage.

The external noise B is superimposed on the current output by the measurement unit as the measurement result from the finger touching the touch panel via the sensor (receiving electrode). When a drive voltage is applied to the transmission electrodes, external noise is superimposed on the current corresponding to the drive voltage.

In any case of external noise, the current flowing through the receiving electrode 3 when no driving voltage is applied to the transmitting electrode 2 is all current due to noise. Therefore, by measuring the current flowing through the receiving electrode 3 when no driving voltage is applied to the transmitting electrode 2, the presence or absence of the external noise A and the external noise B can be easily determined without using complicated filter technology. can do. Here, for example, the maximum value of the amplitude of the current waveform within a certain period of time, its average value, or the maximum value of the square of the current value, or its average value is obtained as the representative value of the current, and the representative value is the magnitude of the external noise. You can say Moreover, it can be determined that there is external noise when the representative value exceeds a predetermined numerical value (threshold value).

The noise considered here is all external noise, and the noise generated inside the touch panel device can be ignored. The noise generated inside the touch panel device is so small that there is no need to take countermeasures against the noise.

FIG. 4 is a flow chart showing the operation of the touch panel device 20 according to one embodiment of the present invention. First, with reference to FIG. 4, an operation example in which the touch panel device 20 detects the presence or absence of noise, applies frequency hopping according to the presence or absence of noise, and identifies touch coordinates will be described.

First, the control unit 7 instructs the driving unit 4 not to apply the driving voltage to any of the transmission electrodes 2 (no instruction to apply the driving voltage). The control unit 7 instructs the measuring unit 5 to measure currents from the plurality of receiving electrodes 3 . The measuring unit 5 measures currents of the plurality of receiving electrodes 3 when no driving voltage is applied (S1).

Next, the control section 7 instructs the noise detection section 6 to determine the presence or absence of noise from the measurement result. The noise detector 6 determines the presence or absence of noise from the current measurement result (S2). The noise detector 6 regards the measured value of the current when no drive voltage is applied or its representative value as the magnitude of the noise. The noise detector 6 determines that there is noise if the measured value of the current or its representative value exceeds the threshold, and determines that there is no noise if it does not.

The control unit 7 determines the frequency, phase and/or duty ratio of the drive voltage according to the presence or absence of noise (S3). For example, when there is no noise, the controller 7 determines the first frequency, first phase and/or first duty ratio. When noise is present, the control unit 7 determines a second frequency different from the first frequency, a second phase different from the first phase, and/or a second duty ratio different from the first duty ratio. The second frequency, second phase, and/or second duty ratio can be preset based on expected noise sources.

Next, the control unit 7 designates the determined frequency, phase, and/or duty ratio of the driving voltage to the driving unit 4, and instructs the driving unit 4 to sequentially apply the driving voltage to the plurality of transmission electrodes 2. . The phase corresponds to the timing of outputting the pulsed driving voltage. The control unit 7 also instructs the measuring unit 5 to measure the currents of the plurality of receiving electrodes 3 by designating the frequency, phase and/or duty ratio of the drive voltage. The drive unit 4 sequentially applies drive voltages to the transmission electrodes 2-1 to 2-n. The measurement unit 5 measures the currents of the plurality of receiving electrodes 3 at timings corresponding to the frequency, phase, and duty ratio of the drive voltage (at timings when the drive voltage changes) (S4).

Next, the control section 7 instructs the coordinate calculation section 8 to perform coordinate calculation using the output from the measurement section 5 . The coordinate calculation unit 8 identifies touch coordinates from the measurement result of the current when the drive voltage is applied (S5).

According to the touch panel device 20 of the present embodiment, the presence or absence of noise can be determined without using complicated filter technology. The touch panel device 20 applies frequency hopping according to the presence or absence of noise (by changing the frequency, phase, and/or duty ratio of the drive voltage) to reduce the influence of noise and identify touch coordinates. It can be carried out.

[Embodiment 2]
Other embodiments of the invention are described below. For convenience of description, members having the same functions as those of the members described in the above embodiments are denoted by the same reference numerals, and description thereof will not be repeated.

(Configuration example)
FIG. 5 is a block diagram showing the configuration of the touch panel device 21 according to this embodiment. The touch panel device 21 includes a touch panel 1 , a drive section 4 , a measurement section 5 , a noise detection section 6 , a control section 7 , a coordinate calculation section 8 and a noise filter section 9 . The touch panel device 21 according to the present embodiment is a device that applies an appropriate noise filter to the noise based on noise-derived signals that appear in a plurality of reception electrodes during a period in which signals are not transmitted from the transmission electrodes. .

The noise detection unit 6 outputs information indicating the presence/absence, magnitude, and/or variation of noise to the control unit 7 .

The control unit 7 is a device that controls the operations of the drive unit 4 , the measurement unit 5 , the noise detection unit 6 , the coordinate calculation unit 8 and the noise filter unit 9 . In addition to the configuration of the first embodiment, the control unit 7 selects a noise filter and changes the strength of the noise filter according to the noise determination result. The control unit 7 instructs the noise filter unit 9 to select a noise filter and/or change the strength of the noise filter.

The coordinate calculation section 8 is a device that performs coordinate calculation from the information output by the noise filter section 9 . The coordinate calculation unit 8 determines the touch coordinates touched by the user based on the capacitance change of each coordinate on the touch panel 1 .

The noise filter unit 9 performs processing (filter processing) to reduce the influence of noise on the information output from the measurement unit 5 based on instructions from the control unit 7 . The noise filter unit 9 outputs information indicating the processed current to the coordinate calculation unit 8 . The noise filter unit 9, for example, calculates an average value or median value, or uses a low-pass filter.

(Operation example)
Noise that is not specified by a specific frequency (for example, noise with a wide range of frequencies generated by a device with discharge) is reduced by a noise filter. In this case, under conditions where noise is strong, the strength of the noise filter is increased to reduce the noise. For example, when calculating an average value, the number of times of input from the sensor (the number of repetitions) is increased, and the average value of the inputs obtained by the increased number of times is output. Therefore, if the strength of the noise filter is increased, the number of times the sensor value (average value) used to calculate the touch coordinate value is input per time is reduced, so the number of times the calculated touch coordinate value is output per time is reduced. decreases.

When the noise filter unit 9 calculates the median value, the number of iterations is set to be an odd number, with a minimum of three. As for the number of times of repetition, it is preferable to use 5 times or more because the effect is small when the number of times is 3 times. The control unit 7 sets the number of repetitions to a larger number as the noise variation (the difference between the maximum value and the minimum value) increases. When the noise filter unit 9 calculates the average value, it is preferable to set the number of repetitions to 5 or more in a situation where noise is superimposed and touch detection is difficult. The control unit 7 sets the number of repetitions to a larger number as the magnitude of noise increases (the S/N ratio deteriorates).

FIG. 6 is a flow chart showing the operation of the touch panel device 21 according to one embodiment of the present invention. First, referring to FIG. 6, touch panel device 21 detects the presence, size, and/or variation of noise, and selects an appropriate noise filter according to the presence, size, and/or variation of noise. Then, an operation example for identifying touch coordinates will be described.

S1 is the same as the operation example of the first embodiment.

Next, the control unit 7 instructs the noise detection unit 6 to determine the presence or absence of noise from the measurement result of the measurement unit 5 . The noise detector 6 determines presence/absence, magnitude, and/or variation of noise from the current measurement result (S10). The noise detector 6 determines that there is noise if the measured current value or its representative value exceeds the threshold, and further determines that the measured current value or its representative value is the magnitude of the noise. The noise detector 6 regards the measured value of the current when no drive voltage is applied or its representative value as the magnitude of the noise. The noise detector 6 determines that there is noise if the measured value of the current or its representative value exceeds the threshold, and determines that there is no noise if it does not.

Next, the control unit 7 selects a noise filter according to noise information (noise presence, size, and/or fluctuation) (S11). For example, the control unit 7 selects the first noise filter (e.g. average filter) if the noise magnitude is equal to or less than the first threshold, and selects the second noise filter (e.g. low-pass filter) may be selected. For example, as the second noise filter, a filter that has a larger processing load (longer processing time) than the first noise filter but can further reduce the influence of noise is used. For example, the control unit 7 may instruct not to use the noise filter when it is determined that noise does not exist. Similarly, the control unit 7 may switch noise filters according to noise fluctuations.

Next, the control unit 7 changes the strength of the noise filter according to the magnitude or fluctuation of noise (S12). The controller 7 sets the strength of the noise filter higher as the magnitude of noise or fluctuation increases. When the noise filter unit 9 calculates an average value or a median value, increasing the number of measurement results used for calculation increases the strength of the noise filter. When the noise filter section 9 includes a low-pass filter, increasing the number of stages increases the strength of the noise filter.

In addition, if the measurement results used in one filtering process of the average value or the median value are discarded in the process of that time, the number of measurements (repetition number) m by the receiving electrode 3 is the number of measurement results matches On the other hand, when the average value is calculated by moving average, the number m of measurements by the receiving electrode 3 does not match the number of measurement results k (m<k) used in calculating the moving average. When obtaining a moving average, the required number of measurement results are stored in memory, and each time the oldest measurement result is discarded and the newest measurement result is added to maintain the required number and average is obtained. The control unit 7 determines the number m of measurements by the receiving electrode 3 according to the set strength of the noise filter.

Next, the control section 7 instructs the drive section 4 to sequentially apply the drive voltage to the plurality of transmission electrodes 2 . The control unit 7 also instructs the measuring unit 5 to measure the currents of the plurality of receiving electrodes 3 . The drive unit 4 sequentially applies drive voltages to the transmission electrodes 2-1 to 2-n. The measuring unit 5 measures the currents of the plurality of receiving electrodes 3 in accordance with the timing at which the drive voltage is applied to each transmitting electrode 2 (S13).

Next, the operation of S13 is performed m times (the number of times corresponding to the strength of the filter) (S14).

Next, if the noise detector 6 determines that there is noise (YES in S15), the process proceeds to S16. If the noise detector 6 determines that there is no noise (NO in S15), the process proceeds to S17.

The control unit 7 instructs the noise filter unit 9 to perform filtering by selecting the determined noise filter and/or changing the strength of the noise filter. The noise filter section 9 filters the output from the measurement section 5 (S16). The noise filter unit 9 outputs to the coordinate calculation unit 8 information indicating the sensor value (current of the receiving electrode 3) after filtering.

If it is determined that there is no noise (NO in S15), the noise filter section 9 outputs information indicating the unfiltered sensor value (the current of the receiving electrode 3) to the coordinate calculation section 8.

Next, the control section 7 instructs the coordinate calculation section 8 to perform coordinate calculation using the output from the noise filter section 9 . The coordinate calculation unit 8 identifies touch coordinates from the (filtered/unfiltered) current measurement results when the drive voltage is applied (S17).

According to the touch panel device 21 of this embodiment, the presence or absence of noise can be determined. The touch panel device 21 selects a noise filter according to the presence/absence, size, and/or variation of noise, and changes the strength of the noise filter, thereby reducing the influence of noise and specifying touch coordinates. can. The touch panel device 21 can reduce the processing load of filter processing when there is no or little noise. Thereby, for example, when there is no or little noise, the touch panel device 21 can increase the number of times of specifying touch coordinates per time (shorten the cycle of specifying processing of touch coordinates).

(Modification 1)
(Configuration example)
FIG. 7 is a block diagram showing the configuration of the touch panel device 22 according to Modification 1. As shown in FIG. This modified example 1 is a modified example of the first embodiment. The touch panel device 22 includes, in addition to the touch panel device 20 in the first embodiment, a non-connection section 10 that is an output terminal that is not connected to any of the transmission electrodes 2 in the driving section 4 .

The drive unit 4 has a plurality of output terminals for outputting drive voltages. A first output terminal among the plurality of output terminals is the non-connecting portion 10 and is not connected to any of the transmission electrodes 2 passing through the touch area of the touch panel 1 . Other output terminals (second and subsequent output terminals) among the plurality of output terminals are connected to the transmission electrode 2 . Upon receiving an instruction to apply the drive voltage from the control unit 7, the drive unit 4 outputs the drive voltage from each output terminal in order from the first output terminal. The non-connected portion 10 does not pass through the touch area of the touch panel 1 (does not cross the receiving electrodes 3).

Since the non-connecting portion 10 is not connected to any of the transmitting electrodes 2 , capacitive coupling is not formed between the non-connecting portion 10 and the receiving electrode 3 on the extension line along the X-axis. Therefore, even if a driving voltage is applied to the non-connecting portion 10, no current flows through the receiving electrode 3 via electrostatic capacitive coupling. Therefore, when the driving voltage is applied to the non-connecting portion 10, the measuring portion 5 can obtain only the noise-derived signal appearing in the receiving electrode 3 during the period when the signal is not transmitted from the transmitting electrode 2. FIG. In this modification, the noise detection section 6 uses the current of the receiving electrode 3 when the drive voltage is applied to the non-connection section 10 to determine noise.

(Operation example)
FIG. 8 is a flowchart showing the operation of the touch panel device 22 in Modification 1. As shown in FIG. First, with reference to FIG. 8, an operation example in which the touch panel device 22 detects the presence or absence of noise, applies frequency hopping according to the presence or absence of noise, and identifies touch coordinates will be described.

First, the control section 7 instructs the drive section 4 to sequentially output drive voltages to a plurality of output terminals. The drive unit 4 sequentially outputs drive voltages to a plurality of output terminals. Here, the frequency, phase, and/or duty ratio of the drive voltage are determined based on the noise determination result of the previous measurement. The control unit 7 operates the measurement unit 5 in accordance with the output of the driving voltage to each output terminal. Also, the control unit 7 operates the noise detection unit 6 in accordance with the output of the drive voltage to the non-connection unit 10 . The measuring section 5 measures the current of the receiving electrode 3 when the driving voltage is output to the non-connecting section 10 (S20). Subsequently, the measuring unit 5 measures the current of the receiving electrode 3 when the driving voltage is output to each transmitting electrode 2 (S4).

S4 and S5 are the same as the operation example of the first embodiment. Note that the coordinate calculation is performed using the measurement results obtained when the plurality of transmission electrodes 2 are driven, without using the current measurement results obtained when the non-connecting portion 10 is driven.

The noise detection unit 6 determines noise from the current of the receiving electrode 3 measured while the drive voltage is being output to the non-connection unit 10 (S2). S3 is the same as the operation example of the first embodiment. The determined frequency, phase, and/or duty ratio of the driving voltage are used as the noise determination result at the next measurement.

According to the touch panel device 22 of the present embodiment, the control section 7 does not need to instruct the drive section 4 not to apply the drive voltage to any of the transmission electrodes 2 . Upon receiving an instruction to start outputting the driving voltage from the control unit 7, the driving unit 4 may sequentially output the driving voltage to the plurality of output terminals. Therefore, the circuit in the drive unit 4 does not need to have a special configuration, and at least one output terminal should be configured so that it is not connected to the transmission electrode 2 . Therefore, the touch panel device 22 can simplify the control method of the controller 7 .

(Modification 2)
(Configuration example)
FIG. 9 is a block diagram showing the configuration of the touch panel device 23 according to Modification 2. As shown in FIG. This modified example 2 is a modified example of the second embodiment. The touch panel device 23 includes a non-connecting section 10 in addition to the touch panel device 21 in the second embodiment. The configurations of the driving portion 4 and the non-connecting portion 10 are the same as those of the first modification.

(Operation example)
FIG. 10 is a flow chart showing the operation of the touch panel device 23 in Modification 2. As shown in FIG. First, referring to FIG. 10, touch panel device 23 detects the presence, size, and/or variation of noise, and selects an appropriate noise filter according to the presence, size, and/or variation of noise. Then, an operation example for identifying touch coordinates will be described.

S20 is the same as the operation example of the first modification. S4 is the same as the operation example of the first embodiment.

Next, the operations of S20 and S4 are repeated m times (the number of times corresponding to the strength of the filter) (S30).

The filtering processes (S15, S16) according to noise and the coordinate calculation (S17) are the same as those of the operation example of the second embodiment. Subsequent S10 to S12 are the same as the operation example of the second embodiment.

According to the touch panel device 23 of the present embodiment, the control section 7 does not need to instruct the drive section 4 not to apply the drive voltage to any of the transmission electrodes 2 . Upon receiving an instruction to start outputting the driving voltage from the control unit 7, the driving unit 4 may sequentially output the driving voltage to the plurality of output terminals. Therefore, the circuit in the drive unit 4 does not need to have a special configuration, and at least one output terminal should be configured so that it is not connected to the transmission electrode 2 . Therefore, the touch panel device 23 can simplify the control method of the controller 7 .

(Modification 3)
The control unit 7 controls the driving unit 4 so as not to apply a voltage to any of the transmitting electrodes 2 in order to measure the noise not only once but also twice or more while making one round of the plurality of transmitting electrodes 2 . section 5 and noise detection section 6 may be controlled.

According to the above configuration, the current measured value or its representative value can be measured a plurality of times when no driving voltage is applied. Therefore, more accurate noise information can be obtained.

(Modification 4)
The control unit 7 may instruct the noise detection unit 6 to acquire the magnitude of noise at each moment, in addition to acquiring the determination result of the presence or absence of noise at regular intervals. The noise detection unit 6 may have a function of identifying frequency characteristics of noise from the magnitude of the noise and a certain period (noise measurement interval).

The control unit 7 may change the frequency, phase, and duty ratio of the drive voltage so as to avoid the frequency of the noise (to reduce the influence) according to the frequency characteristics of the noise. According to the above configuration, more appropriate frequency hopping can be performed based on the frequency characteristics of noise.

Alternatively, the control unit 7 may change the strength of the noise filter according to the frequency characteristics of noise. The frequency characteristics of noise depend on the type of noise source. The control unit 7 can select the type, combination, and/or strength of noise filters suitable for an assumed noise source corresponding to the frequency characteristics of the noise. Note that the control unit 7 may select a combination of a plurality of noise filters according to noise (presence or absence of noise, size, variation, and/or frequency characteristics).

The control blocks of the touch panel devices 20, 21, 22, and 23 (especially the noise detection section 6, the control section 7, the coordinate calculation section 8, and the noise filter section 9) are logic circuits (hardware) formed in an integrated circuit (IC chip) or the like. software) or software.

In the latter case, the touch panel devices 20, 21, 22, and 23 are provided with computers that execute instructions of programs, which are software that implements each function. This computer includes, for example, one or more processors, and a computer-readable recording medium storing the program. In the computer, the processor reads the program from the recording medium and executes it, thereby achieving the object of the present invention. As the processor, for example, a CPU (Central Processing Unit) can be used. As the recording medium, a "non-temporary tangible medium" such as a ROM (Read Only Memory), a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. In addition, a RAM (Random Access Memory) for developing the above program may be further provided. Also, the program may be supplied to the computer via any transmission medium (communication network, broadcast wave, etc.) capable of transmitting the program. Note that one aspect of the present invention can also be implemented in the form of a data signal embedded in a carrier wave in which the program is embodied by electronic transmission.

The present invention is not limited to the above-described embodiments, but can be modified in various ways within the scope of the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. is also included in the technical scope of the present invention.

1 touch panel 2 transmission electrode 3 reception electrode 4 drive unit 5 measurement unit 6 noise detection unit 7 control unit 8 coordinate calculation unit (coordinate identification unit)
9 noise filter portion 10 non-connecting portion 11 substrate 12 insulating layer 13 front cover 20, 21, 22, 23 touch panel device

Claims (7)

A mutual capacitance touch panel comprising a plurality of transmitting electrodes and a plurality of receiving electrodes forming capacitive coupling;
a drive unit that applies a drive voltage to the plurality of transmission electrodes;
a measuring unit that measures outputs from the plurality of receiving electrodes;
a coordinate identification unit that identifies touch coordinates using the measurement values obtained by the measurement unit when the drive voltage is applied to the plurality of transmission electrodes;
A noise detection unit that detects noise using the measurement values of the measurement unit obtained when the drive voltage is not applied to the plurality of transmission electrodes ,
The drive unit includes a plurality of output terminals for outputting the drive voltage,
The touch panel device, wherein at least one of the plurality of output terminals is not connected to the plurality of transmission electrodes, and a plurality of other output terminals are connected to the plurality of transmission electrodes. The frequency, phase, and duty ratio of the drive voltage , or the frequency, phase, and duty ratio of the drive voltage are determined according to the detected noise, and the drive unit determines a control unit that designates the frequency, phase, and duty ratio of the drive voltage , or specifies the frequency, phase, and duty ratio of the drive voltage , and instructs to apply the drive voltage to the plurality of transmission electrodes; The touch panel device of claim 1 , comprising: A noise filter unit that performs processing to reduce the influence of noise on the measured value of the measurement unit,
2. The touch panel device according to claim 1 , further comprising a control unit that determines whether or not to perform processing for reducing the influence of noise on said measurement value of said measurement unit according to said noise. a noise filter unit that performs processing to reduce the influence of noise on the measured value of the measurement unit;
2. The touch panel device according to claim 1 , further comprising a control section that selects a noise filter used by said noise filter section according to said noise. a noise filter unit that performs processing to reduce the influence of noise on the measured value of the measurement unit;
2. The touch panel device according to claim 1 , further comprising a control section that changes strength of a noise filter used by said noise filter section according to said noise. a noise detection unit that identifies the magnitude of the noise at a plurality of timings;
2. The touch panel device according to claim 1 , further comprising a control unit that specifies the frequency characteristic of the noise from the magnitude of the noise and the measurement interval of the noise. A control method for a touch panel device including a mutual capacitance touch panel including a plurality of transmission electrodes and a plurality of reception electrodes forming capacitive coupling,
a driving step of applying a driving voltage to the plurality of transmission electrodes;
a measuring step of measuring outputs from the plurality of receiving electrodes;
a coordinate identifying step of identifying touch coordinates using measured values of the outputs obtained when the driving voltage is applied to the plurality of transmitting electrodes;
a noise detection step of detecting noise using measurements of the outputs obtained when the drive voltage is not applied to the plurality of transmitting electrodes ;
A drive unit that applies a drive voltage to the plurality of transmission electrodes includes a plurality of output terminals that output the drive voltage,
A control method for a touch panel device, wherein at least one output terminal of the plurality of output terminals is not connected to the plurality of transmission electrodes, and a plurality of other output terminals are connected to the plurality of transmission electrodes.

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