JP6556421B2 - Touch panel device and touch detection method - Google Patents

Description

  The present invention relates to a capacitive touch panel device and a touch detection method for a touch panel.

  A capacitive touch panel device detects a touch point by measuring a change in capacitance due to a finger touch or the like, and is applied to, for example, a mobile phone or a tablet PC (for example, Patent Documents). 1).

  FIG. 4 is a block diagram illustrating a driving circuit of a display device including a conventional capacitive touch panel device. 4, this drive circuit is connected to the touch panel controller 20 connected to the touch panel 10, the timing controller 40 connected to the LCD (Liquid Crystal Display) 30 and the LCD 30, and the touch panel controller 20 and the timing controller 40. The host controller 50 is provided.

  The touch panel controller 20 outputs a drive signal (sensing signal) to the drive electrode Tx of the touch panel 10 and receives a scan signal from the read electrode Rx of the touch panel 10. Further, the touch panel controller 20 outputs a coordinate data signal including presence / absence of touch to the host controller 50 based on the input scan signal.

  The timing controller 40 outputs an LCD control signal to the LCD 10 based on the clock signal, the image data signal, and the horizontal synchronization signal input from the host controller 50, and executes liquid crystal writing on the LCD 30. The image data signal includes image data internally processed by the host controller 50 based on the coordinate data from the touch panel controller 20.

  FIG. 5 is an explanatory diagram showing electrodes constituting the touch panel 10 shown in FIG. In FIG. 5, the touch panel 10 has a plurality of drive electrodes Tx (for example, Tx1 to Tx6 sensor lines) and a plurality of readout electrodes Rx (for example, Rx1 to Rx6 sensor lines) insulated from the drive electrodes Tx. doing. Moreover, since the touch panel 10 is attached to the upper part of the LCD 30, a transparent and conductive material such as ITO (Indium Tin Oxide) is used.

  FIG. 6 is an explanatory diagram showing a change in mutual capacitance between the drive electrode Tx and the read electrode Rx depending on the presence or absence of touch in the touch panel 10 shown in FIG. In FIG. 6, (a) shows the mutual capacitance when there is no touch, (b) shows the mutual capacitance when there is a touch, and the dotted line between the electrodes in the figure shows the lines of electric force.

  In FIG. 6A, the mutual capacitance between the drive electrode Tx and the read electrode Rx when there is no touch is Cm1 + Cm2. In FIG. 6B, when there is a touch, since the finger has conductivity, the finger becomes an electrode and Cm2 disappears. Instead, Ct−f (between the drive electrode Tx and the finger). Capacitance) and Cr-f (capacitance between the finger and the readout electrode Rx) are generated.

  FIG. 7 is a circuit diagram showing an equivalent circuit of the capacitance of the touch panel 10 shown in FIG. 7A shows an equivalent circuit when there is no touch, and FIG. 7B shows an equivalent circuit when there is a touch. In FIG. 7, the additional capacitance attached to the sensor line of the drive electrode Tx is Ctx, and the additional capacitance attached to the sensor line of the readout electrode Rx is Crx.

  In FIG. 7A, the mutual capacitance between the drive electrode Tx and the read electrode Rx when there is no touch is Cm1 + Cm2, as shown in FIG. 7B, when touched, Cm2 disappears and Ct-f and Cr-f generated between the fingers are added as shown in FIG. 6B.

  FIG. 8 is a circuit diagram showing an equivalent circuit obtained by extracting only the portion related to the voltage not considering the transient response from the equivalent circuit shown in FIG. 8A shows an equivalent circuit when there is no touch, and FIG. 8B shows an equivalent circuit when there is a touch.

  In FIG. 8A, the voltage Vrx that appears at the readout electrode Rx when there is no touch is expressed by the following equation (1).

(Cm1 + Cm2) × (Vtx−Vrx) = Crx × Vrx
Vrx = (Cm1 + Cm2) / (Cm1 + Cm2 + Crx) × Vtx (1)

  Subsequently, in FIG. 8B, when there is a touch, the voltage Vrx ′ appearing on the readout electrode Rx is expressed by the following equation (2).

Cm1 (Vtx−Vrx) = (Crx + Cr−f) × Vrx ′
Vrx ′ = Cm1 / (Cm1 + Crx + Cr−f) × Vtx (2)

  Further, the relationship between the voltage Vrx and the voltage Vrx ′ appearing at the readout electrode Rx is expressed by the following equation (3).

Vrx: Vrx '
= (Cm1 + Cm2) / (Cm1 + Cm2 + Crx): Cm1 / (Cm1 + Crx + Cr−f)
= (Cm1 + Cm2) × (Cm1 + Crx + Cr−f): Cm1 × (Cm1 + Cm2 + Crx)
= Cm1 ² + Cm1 * Cm2 + Cm1 * Crx + Cm1 * Cr-f + Cm2 * Crx + Cm2 * Cr-f: Cm1 ² + Cm1 * Cm2 + Cm1 * Crx (3)

Here, when Cm1 ² + Cm1 × Cm2 + Cm1 × Crx = Csum, the above equation (3) is expressed by the following equation (4).

    Vrx: Vrx ′ = Csum + Cm1 × Cr−f + Cm2 × Crx + Cm2 × Cr−f: Csum (4)

  From Expression (4), it can be seen that the voltage Vrx and the voltage Vrx ′ appearing at the readout electrode Rx are in a relationship of Vrx> Vrx ′.

  FIG. 9 is an explanatory diagram showing a voltage appearing on the read electrode Rx when a drive signal of the pulse voltage Vtx is applied to the drive electrode Tx of the equivalent circuit shown in FIG. In FIG. 9, (a) shows the voltage of the drive electrode Tx, (b) shows the voltage of the read electrode Rx when there is no touch, and (c) shows the voltage of the read electrode Rx when there is a touch. Yes.

  As can be seen from FIG. 9, the voltage Vrx ′ when there is a touch is smaller than the voltage Vrx when there is no touch, as described with reference to FIG. 8. In FIG. 9, since the difference ΔVrx between the voltage Vrx and the voltage Vrx ′ is actually a small value, a plurality of pulse voltages Vtx are applied to the drive electrode Tx in one frame, and the voltage difference ΔVrx is integrated a plurality of times. The presence of touch is detected.

  FIG. 10 is a block diagram showing in detail the configuration of the touch panel controller 20 shown in FIG. In FIG. 10, the touch panel controller 20 includes a Tx pulse generator 21, an Rx detector 22, a coordinate calculator 23, and a non-touch memory 24. The Rx detector 22 includes an integrating circuit 22a and an A / D converter 22b.

  The Tx pulse generator 21 applies a plurality of pulse voltages Vtx to each sensor line of the drive electrode Tx shown in FIG. The Rx detector 22 detects a plurality of pulse voltages Vtx applied in units of Tx sensor lines as scan signals through the equivalent circuit shown in FIG. 7, integrates the detected data with the integration circuit 22a, and then integrates the detected data. The result is A / D converted by the A / D converter 22b and output.

  FIG. 11 is a diagram for specifically explaining detection of a touch point by the coordinate calculation unit 23 illustrated in FIG. 10. Referring to FIG. 11, the coordinate calculation unit 23 takes the difference between the detection data obtained by the Rx detection unit 22 and the non-touch storage data (predetermined base data) stored in the non-touch memory 24. Generate difference data.

  Further, when the generated difference data is equal to or greater than a predetermined threshold value, the coordinate calculation unit 23 considers that there is a touch, calculates the coordinates of the touch point, and outputs a coordinate data signal. The non-touch storage data is data stored in advance in the non-touch memory 24 as data in a state where there is no touch.

  Hereinafter, the processing of the touch panel controller 20 illustrated in FIG. 10 will be described with reference to the flowchart of FIG. Note that the flowchart of FIG. 12 shows processing for one frame.

  First, the Tx pulse generator 21 and the Rx detector 22 scan each sensor line of the drive electrode Tx (apply a pulse voltage Vtx to each sensor line), and acquire detection data from the read electrode Rx (step S1). .

  Subsequently, the coordinate calculation unit 23 takes the difference between the detection data from the Rx detection unit 22 and the storage data without touch stored in the touchless memory 24 to generate difference data (step S2).

  Next, the coordinate calculation part 23 determines the presence or absence of a touch based on the produced | generated difference data (step S3).

  If it is determined in step S3 that there is a touch (that is, Yes), the coordinate calculation unit 23 calculates the coordinates of the touch point, outputs a coordinate data signal (step S4), and proceeds to step S1. To do.

  On the other hand, if it is determined in step S3 that there is no touch (that is, No), the coordinate calculation unit 23 proceeds to step S1 without calculating the coordinates of the touch point.

  Here, in a certain frame, each sensor line of the drive electrode Tx is scanned in step S1, and in the next frame, the interval (cycle) until each sensor line of the drive electrode Tx is scanned again in step S1 is 60. The presence / absence of a touch is detected at each interval, and the coordinates of the touch point are calculated.

JP 2010-232162 A

However, the prior art has the following problems.
Capacitive touch panel devices detect touch points while wearing non-conductive gloves (hereinafter also simply referred to as “gloves”), unlike resistive film systems that sense pressure contact. Becomes difficult.

  FIG. 13 is an explanatory view showing a touch signal in a conventional capacitive touch panel device in comparison with a bare hand state and a gloved state. The touch signal is difference data generated by the coordinate calculation unit 23. In FIG. 13, the touch signal when wearing gloves has a low signal level and does not reach the threshold set in consideration of the influence of noise or the like, so that the touch point cannot be detected.

  Here, when the glove is worn, the signal level of the touch signal is lowered by wearing the glove so that the voltage Vrx that appears on the read electrode Rx when there is no touch and the voltage Vrx that appears on the read electrode Rx when there is a touch. This is because the difference from 'becomes smaller (see FIG. 8 described above).

  FIG. 14 is an explanatory diagram showing a change in mutual capacitance between the drive electrode Tx and the read electrode Rx when touched in a state where a glove is worn in a conventional capacitive touch panel device. In FIG. 14, the distance between the finger and the readout electrode Rx is increased by using a non-conductive glove, so that the capacitance Cr-f is reduced (Cr-f_g).

  That is, in the above formula (4) (Vrx: Vrx ′ = Csum + Cm1 × Cr−f + Cm2 × Crx + Cm2 × Cr−f: Csum), the capacitance Cr−f that is a factor of the difference between the voltage Vrx and the voltage Vrx ′ is small. Therefore, the touch signal becomes small.

  As a method for increasing the signal level of the touch signal, it is conceivable to increase the pulse voltage Vtx in order to increase the absolute value of the voltage Vrx ′. However, this is difficult to realize due to the increased power consumption.

  As another method, it is conceivable to increase the number of integrations by increasing the number of pulses in one frame applied to each sensor line of the drive electrode Tx. However, in this case, it is difficult to achieve the period of 60 to 120 Hz in the flowchart shown in FIG.

  For this reason, it is necessary to remove the gloves before operation in winter when the temperature is low, such as in winter, or it is necessary to purchase special gloves woven with conductive fibers, resulting in low user convenience. There is a problem.

  The present invention has been made to solve the above-described problems, and can detect a touch point even when a non-conductive glove is worn, improving user convenience. It is an object to obtain a touch panel device and a touch detection method that can be performed.

The touch panel device according to the present invention is a touch panel device provided with a capacitive touch panel, and takes a difference between data detected by each sensor of the touch panel and predetermined base data to obtain a difference for one frame. A coordinate calculation unit that detects presence / absence of touch based on the difference data, and an integration memory that stores the difference data, and the coordinate calculation unit uses the difference data for one frame as a threshold value. In comparison, if the difference data for one frame is equal to or greater than the threshold, the touch of the user's bare hands is detected, the coordinates of the touch point are calculated, and the difference data for one frame is used as the threshold. In comparison, if the difference data for one frame is smaller than the threshold value, a touch due to a non-conductive object is detected, and this difference is stored in the integration memory. The minute data is stored, and the presence / absence of touch is detected by comparing the accumulated difference data with a threshold value based on the difference data accumulated a predetermined number of times in the accumulation memory.

The touch detection method according to the present invention is a touch detection method executed by a touch panel device including a capacitive touch panel, and calculates a difference between data detected by each sensor of the touch panel and predetermined base data. The difference data generation step for generating the difference data for one frame, the difference data for one frame is compared with a threshold value, and if the difference data for one frame is equal to or greater than the threshold value, the user's bare hands When a touch is detected, the coordinate calculation step for calculating the coordinates of the touch point based on the difference data for one frame, the difference data for one frame is compared with a threshold value, and the difference data for one frame Is smaller than the threshold value, it is a case where a touch by a non-conductive object is detected, and this difference data is stored in the memory. And a detection step of detecting presence / absence of touch by comparing the accumulated difference data with a threshold value based on the difference data accumulated in the memory a predetermined number of times.

According to the touch panel device and the touch detection method according to the present invention, when a touch is detected based on the difference data for one frame, the coordinates of the touch point are calculated, and the touch is detected based on the difference data for one frame. If not detected, the difference data is stored, and the presence or absence of a touch is detected based on the difference data accumulated at least twice.
Therefore, even in a state where non-conductive gloves are worn, the touch point can be detected, and the convenience for the user can be improved.

It is a figure for demonstrating the summary of the touchscreen apparatus and touch detection method which concern on this invention. It is a block diagram which shows in detail the structure of the touchscreen controller of the touchscreen apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows the process of the touch panel controller shown in FIG. It is a block diagram which shows the drive circuit of the display apparatus provided with the conventional capacitive touch panel apparatus. It is explanatory drawing which shows the electrode which comprises the touchscreen shown in FIG. FIG. 5 is an explanatory diagram showing a change in mutual capacitance between the drive electrode and the readout electrode depending on the presence or absence of touch in the touch panel shown in FIG. 4. It is a circuit diagram which shows the equivalent circuit of the electrostatic capacitance of the touch panel shown in FIG. FIG. 8 is a circuit diagram illustrating an equivalent circuit in which only a portion related to a voltage not considering a transient response is extracted from the equivalent circuit illustrated in FIG. 7. It is explanatory drawing which shows the voltage which appears in a read-out electrode when the drive signal of pulse voltage Vtx is applied to the drive electrode of the equivalent circuit shown in FIG. FIG. 5 is a block diagram showing in detail the configuration of the touch panel controller shown in FIG. 4. It is a figure for demonstrating concretely the detection of the touch point by the coordinate calculation part shown in FIG. It is a flowchart which shows the process of the touch panel controller shown in FIG. It is explanatory drawing which compares and shows the touch signal in the conventional electrostatic capacitance type touch panel apparatus with the state of a bare hand and the state which wore the glove. In the conventional electrostatic capacitance type touch panel device, it is explanatory drawing which shows the change of the mutual capacitance of a drive electrode and a read electrode at the time of touching in the state which wore the glove.

  Hereinafter, preferred embodiments of a touch panel device and a touch detection method according to the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts will be described with the same reference numerals.

Embodiment 1 FIG.
First, the gist of the present invention will be described with reference to FIG. FIG. 1 is a diagram for explaining the gist of a touch panel device and a touch detection method according to the present invention. In FIG. 1, as described above, the signal level of the touch signal per frame is low when a non-conductive glove is worn.

  However, as shown in FIG. 1, even when a glove is worn, the total value of the touch signals can exceed the threshold by integrating the touch signals for a plurality of frames. Therefore, a touch point can be detected even when a non-conductive glove is worn.

  FIG. 2 is a block diagram showing in detail the configuration of touch panel controller 20A of the touch panel device according to Embodiment 1 of the present invention. In FIG. 2, the touch panel controller 20 </ b> A includes a coordinate calculation unit 23 </ b> A instead of the coordinate calculation unit 23 illustrated in FIG. 10, and further includes an integration memory 25. The other configuration of the touch panel controller 20A is the same as that shown in FIG.

  The coordinate calculation unit 23A takes the difference between the detection data obtained by the Rx detection unit 22 and the non-touch storage data stored in the non-touch memory 24, and obtains difference data for one frame (a touch signal for one frame). ) Is generated. In addition, when the touch signal for one frame is equal to or greater than the threshold, the coordinate calculation unit 23A calculates the coordinates of the touch point and outputs a coordinate data signal.

  On the other hand, when the coordinate calculation unit 23A cannot detect a touch point with a touch signal for one frame, the coordinate calculation unit 23A stores the touch signal in the integration memory 25 and n (n is arbitrarily set in the integration memory 25). The presence or absence of a touch is detected based on the touch signal accumulated two times. Note that the coordinate calculation unit 23A resets the integration memory 25 when the touch point cannot be detected by the touch signal integrated n times.

  Hereinafter, the processing of the touch panel controller 20A illustrated in FIG. 2 will be described with reference to the flowchart of FIG. Note that the flowchart of FIG. 3 shows processing for one frame.

  First, the Tx pulse generator 21 and the Rx detector 22 scan each sensor line of the drive electrode Tx (apply a pulse voltage Vtx to each sensor line), and acquire detection data from the read electrode Rx (step S1). .

  Subsequently, the coordinate calculation unit 23 takes the difference between the detection data from the Rx detection unit 22 and the storage data without touch stored in the touchless memory 24 to generate difference data (step S2).

  Next, the coordinate calculation unit 23A determines whether or not there is a touch based on the generated difference data (step S3).

  If it is determined in step S3 that there is a touch (that is, Yes), the coordinate calculation unit 23A calculates the coordinates of the touch point and outputs a coordinate data signal (step S4).

  Subsequently, the coordinate calculation unit 23A resets the integration memory 25 (step S5), and proceeds to step S1.

  On the other hand, if it is determined in step S3 that there is no touch (that is, No), the coordinate calculation unit 23A stores the touch signal (difference data) in the integration memory 25 (step S6).

  Next, the coordinate calculation unit 23A determines whether or not the touch signals have been integrated n times (step S7).

  If it is determined in step S7 that n times have been integrated (that is, Yes), the coordinate calculation unit 23A determines the presence or absence of a touch based on the touch signal that has been integrated n times (step S8).

  If it is determined in step S8 that there is a touch (that is, Yes), the process proceeds to step S4, where the coordinate calculation unit 23A calculates the coordinates of the touch point and outputs a coordinate data signal.

  On the other hand, if it is determined in step S8 that there is no touch (that is, No), the coordinate calculation unit 23A resets the integration memory 25 (step S9), and proceeds to step S1.

  If it is determined in step S7 that the integration has not been performed n times (that is, No), the coordinate calculation unit 23A proceeds to step S1 without calculating the coordinates of the touch point.

  In this way, by integrating the touch signals for a plurality of frames, the pulse voltage Vtx is not increased, and the normal touch point detection is maintained with the period of 60 to 120 Hz in the flowchart shown in FIG. Thus, it is possible to detect a touch point in a state where a non-conductive glove that cannot be detected at present is worn.

As described above, according to the first embodiment, when a touch is detected based on the difference data for one frame, the coordinates of the touch point are calculated, and the touch is detected based on the difference data for one frame. If not, the difference data is stored, and the presence or absence of a touch is detected based on the difference data accumulated at least twice.
Therefore, in order to operate the touch panel, the user is freed from the cumbersome work of removing his / her worn gloves, and free from the limitation of the choice of having to purchase conductive gloves.
Therefore, even in a state where non-conductive gloves are worn, the touch point can be detected and the convenience for the user can be improved.

  10 touch panel, 20, 20A touch panel controller, 21 Tx pulse generation unit, 22 Rx detection unit, 22a integration circuit, 22b conversion unit, 23 coordinate calculation unit, 24 non-touch memory, 25 integration memory, 40 timing controller, 50 host controller.

Claims (4)

A touch panel device including a capacitive touch panel,
A coordinate calculation unit that takes the difference between the data detected by each sensor of the touch panel and predetermined base data to generate difference data for one frame, and detects presence / absence of touch based on the difference data; ,
An integration memory for storing difference data,
The coordinate calculator is
When the difference data for one frame is compared with a threshold and the difference data for one frame is equal to or greater than the threshold, a touch with a user's bare hand is detected. Calculate the coordinates of the touch point based on the difference data,
When the difference data for one frame is compared with the threshold value, and the difference data for one frame is smaller than the threshold value, a touch by a non-conductive object is detected, and the integration memory The touch panel device detects the presence or absence of a touch by storing the difference data and comparing the accumulated difference data with the threshold value based on the difference data accumulated a predetermined number of times in the accumulation memory. The touch panel device according to claim 1, wherein the coordinate calculation unit resets the integration memory when a touch is detected based on the difference data for one frame. The touch panel device according to claim 1, wherein the coordinate calculation unit resets the accumulation memory when a touch is not detected even by difference data accumulated in the accumulation memory a predetermined number of times. A touch detection method executed by a touch panel device including a capacitive touch panel,
A difference data generation step of generating difference data for one frame by taking a difference between data detected by each sensor of the touch panel and predetermined base data;
When the difference data for one frame is compared with a threshold and the difference data for one frame is equal to or greater than the threshold, a touch with a user's bare hand is detected. A coordinate calculation step for calculating the coordinates of the touch point based on the difference data;
When the difference data for one frame is compared with the threshold and the difference data for one frame is smaller than the threshold, a touch by a non-conductive object is detected, and the difference data Storing in the memory, and detecting based on the difference data accumulated a predetermined number of times in the memory and detecting the presence or absence of touch by comparing the accumulated difference data with the threshold value;
A touch detection method comprising:

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