JP2013156895A - Touch position correction processing method for touch panel, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a touch position correction technology which enables accurate detection of a touch position even when a pressure sensor value increases or decreases depending on handling and tilting of a touch panel.SOLUTION: A touch position correction processing method includes the steps of: determining, based on an output value of a pressure sensor 3, whether or not a pressing force is applied from outside to a cover panel 2; constantly measuring a difference between an output value of the pressure sensor 3 when no pressing force is applied from outside and a reference value of the pressure sensor 3, and recording the difference in a stable state as a correction value; and calculating, using an output value of the pressure sensor 3 when a pressing force is applied from outside and the recorded correction value, coordinates on the cover panel 2 at which the pressing force is applied. The reference value is an output value of the pressure sensor 3 when a touch panel 10 stands still in a horizontal state and no pressing force is applied from outside.

Description

  The present invention relates to a touch position correction processing method and program for a touch panel.

  In recent years, touch panel devices have been widely used in tablet-type mobile phones, electronic books, PCs (Personal Computers), and the like. There are various types of touch panels, and among them, a capacitive method and a resistive film method are known as representative methods. However, the following problems are pointed out in these methods.

[Capacitance method]
-Touch is not detected unless touched by an electrical conductor. For this reason, operation cannot be performed when a stylus pen or gloves are worn and touched. It is also vulnerable to surface contamination.
[Resistive film type]
-Since two or more transparent metal electrodes are required on the display surface of the touch panel, transparency is low and visibility is poor.

In addition, both systems have a structure that is difficult to increase in size due to a decrease in accuracy of detecting the touch position and a problem in cost.
As a method for solving these problems, there is a touch panel using three or more pressure sensors. (For example, see Patent Documents 1 to 4).

JP 61-051229 A Japanese Patent Laid-Open No. 61-177531 Japanese Patent Laid-Open No. 60-230229 JP 2005-524914 A

  In a touch panel using a pressure sensor, it is important to improve the accuracy of the pressure sensor to realize a quick response and to improve the detection accuracy of the touch position. In recent years, a wide variety of mobile terminals such as smartphones and tablet PCs have been provided. In these mobile terminals, since the user can operate with a favorite posture, the posture of the touch panel changes. That is, the spatial orientation of the touch panel during use is not always constant.

  For this reason, when a pressure sensor with high sensitivity is used, there is a problem in that the touch position cannot be accurately detected because the value of the pressure sensor changes depending on how the mobile terminal is held, moves, and tilts.

  The present invention has been made in view of such circumstances, and provides a touch position correction technique that can accurately detect a touch position even if the value of a pressure sensor increases or decreases due to the handling or inclination of the touch panel. Objective.

  The present invention for solving the above problems is a touch position correction processing method of a touch panel comprising a substantially transparent cover panel to which a pressing force is applied and a plurality of pressure sensors for detecting the pressing force of the cover panel. Determining whether or not external pressure is applied to the cover panel from the output value of the pressure sensor; and output value of the pressure sensor and the pressure sensor when no external pressure is applied A step of constantly measuring a difference between the reference value and a stable state difference as a correction value, and an output value of the pressure sensor when a pressing force is applied from the outside and the recorded correction value. And calculating a coordinate on the cover panel to which the pressing force is applied, and the reference value is an external value when the touch panel is left in a horizontal state. It is the pressure sensor is an output value touch position correction processing method in a state where the pressing force is not applied in et.

  According to the touch position correction technique of the touch panel of the present invention, it is possible to detect the touch position with high accuracy even when the value of the pressure sensor changes due to the handling of the panel or the change of the tilt.

  In addition, correction of the touch position of the touch panel is realized only by software without using a device such as a dedicated sensor, so that there are few restrictions on mounting, and a touch panel that can be used for various purposes at low cost is realized.

The figure which shows the structure of the touch panel to which the touch position correction technique of the touch panel of this Embodiment is applied. The figure which shows the main control blocks of the touch panel of this Embodiment. The figure for demonstrating the basic view of the position correction method of the touchscreen in this Embodiment. The figure for demonstrating the basic view of the position correction method of the touchscreen in this Embodiment. The flowchart which shows the whole process sequence of the position correction of the touch panel in this Embodiment. The figure which shows the variable parameter used in the position correction process of the touchscreen in this Embodiment. The flowchart which shows the correction value measurement process sequence in this Embodiment. The flowchart which shows the general | schematic procedure of the correction value decision flag clear process at the time of no stationary touch in this Embodiment. The flowchart which shows the outline procedure of the correction value decision flag clear process by the sensor value fluctuation | variation in this Embodiment.

  FIG. 1 is a diagram illustrating a configuration of a touch panel to which the touch position correction technique for a touch panel according to the present embodiment is applied.

  The touch panel 10 includes a liquid crystal display panel (LCD) 1, a cover panel 2, a pressure sensor 3, a pressure sensor control unit 4, and a pressure sensor control board (not shown). The pressure sensor 3 is provided in the vicinity of the four apexes of the rectangular liquid crystal display panel 1 with the back surface supported by a base plate (not shown). A transparent cover panel 2 is disposed on the front surface of the liquid crystal display panel 1. And the pressure sensor control part 4 detects the output (pressure value) of each pressure sensor 3 suitably. The pressure sensor control unit 4 includes an A / D converter, a processor, and a memory.

  Each pressure sensor 3 is provided in a size and shape such that a gap is secured between the pressure sensor 3 and the liquid crystal display panel (LCD) 1 when the cover panel 2 is pressed. Therefore, when a touch pressure is applied to the cover panel 2 by touching the cover panel 2 with a finger or the like, a signal corresponding to the touch pressure is output from the pressure sensor 3 that is narrowly pressed against the base plate and the cover panel 2. . Then, the touch pressure is divided into the respective pressure sensors 3 by the coordinates touched on the cover panel 2. Accordingly, the coordinates on the touched cover panel 2 can be obtained by obtaining pressure values from the respective pressure sensors 3 and obtaining a solution of the balance between the touch pressure and the force and moment of each pressure sensor 3. it can.

  Here, the pressure value of the pressure sensor 3 is not zero when there is no touch, but has an initial value due to the weight of the cover panel 2 and the pressure applied during assembly. This corresponds to the difference obtained by subtracting the initial value from the pressure value of the pressure sensor 3.

FIG. 2 is a diagram showing main control blocks of the touch panel of the present embodiment. The control block that controls the operation of the touch panel 10 includes a force management block 20 and a display processing block 30.
The force management block 20 calculates and manages the touched coordinates based on the output values of the respective pressure sensors 3. The display processing block 30 displays an image such as a pointer on the liquid crystal display panel 1. The force management block 20 and the display processing block 30 exchange information via the communication line 28.

  The force management block 20 includes a main management unit 21, a communication unit 22, a timer processing unit 23, a pressure sensor processing unit 24, a correction value management unit 25, and a coordinate management unit 26.

  The main management unit 21 manages the operation of the force management block 20 in an integrated manner. The communication unit 22 is a communication interface for exchanging information with the display processing block 30. The timer processing unit 23 generates a timer interrupt at a set time interval. By this timer interruption, the correction value management unit 25 starts execution of processing for measuring the correction value of the sensor output value.

  As described above, even when a force from the outside of the touch panel is not applied, for example, the touch panel 10 is held by a hand and a state where the touch panel 10 is left in a horizontal place (hereinafter referred to as “stationary”). The output value of the pressure sensor 3 is different from the “no touch state”. Therefore, the correction value management unit 25 acquires a difference between the sensor output when not touched and the sensor output value when there is no stationary touch as a correction value.

  The pressure sensor processing unit 24 acquires the output value of each pressure sensor 3 via the A / D converter of the pressure sensor control unit 4. The coordinate management unit 26 calculates and manages the coordinates of the touched position from the output of the pressure sensor processing unit 24 and the correction value obtained by the correction value management unit 25. The main management unit 21 acquires coordinates from the coordinate management unit 26 when touch coordinates are required, such as when a touch coordinate is requested from the display processing block 30.

  The display processing block 30 is provided with a main control unit 31, a communication unit 32, and a drawing unit 33. The main control unit 31 manages the operation of the display processing block 30 in an integrated manner. The communication unit 32 is a communication interface for exchanging information with the force management block 20. The drawing unit 33 generates and outputs a display image such as a pointer on the liquid crystal display panel 1.

  The display processing block 30 acquires the coordinates touched from the force management block 20 via the communication line 28. At that time, the display processing block 30 outputs a coordinate transmission request, and the force management block 20 outputs the latest coordinates of the touched position (X coordinate, Y coordinate), the status of the touch operation, and the like to the display processing block 30. . The drawing unit 33 displays a pointer image corresponding to the status on the liquid crystal display panel 1 based on the calculated coordinates.

  3 and 4 are diagrams for explaining the basic concept of the touch panel correction method according to the present embodiment.

  FIG. 3 (1) shows a reference “no stationary touch state”, that is, a state where the touch panel 10 is placed quietly horizontally and no external force such as touch is applied. .

  Each value of the pressure sensor (A to D) 3 in this state is set as an initial value Kx. Here, for the sake of explanation, it is assumed that the initial value Kx = + 100. The initial value Kx is obtained and set in advance by other means. The subscript x = 1 to 4 represents each pressure sensor 3.

  In this state, the pressure sensor 3 of the touch panel 10 is applied with the weight of the cover panel 2 and the panel holding pressure during assembly.

  However, when the touch panel is not fixed horizontally, such as being held by hand, the pressure of the pressure sensor shaft component force of the gravity force of the cover panel 2 due to the tilt of the touch panel, and the pressure such as deformation due to the holding force Even if the sensor is not touched due to various reasons such as the influence on the sensor axis component force or the influence of acceleration on the mass of the cover panel due to handling with movement, the sensor output value varies. Hereinafter, a state where the touch panel is not fixed horizontally is referred to as “a state without tilt touch”.

Then, a contact force is applied to the pressure sensor 3 by touching the cover panel 2, and the touch contact force T is a detection value difference rx detected by each pressure sensor 3, as represented by the equation (1), that is, This is the sum of differences obtained by subtracting the initial value Kx from the detection value Rx.
Touch contact force T = Σ (detection value Rx−initial value Kx) (1)
Detected value difference rx = Rx−Kx
The subscript x = 1 to 4 represents each pressure sensor.

  Then, using each detection value difference rx = (detection value Rx−initial value Kx), the coordinate management unit 26 calculates the coordinates of the touched position. The coordinates of the touched position can be obtained by obtaining a solution of the balance between the detected value difference rx of each pressure sensor (A to D) 3 and the touch contact force T and the balance between the moments. Since this method is a known technique, a detailed description thereof will be omitted.

FIGS. 3B and 4 show a state where the touch panel 10 is tilted such as being held by a hand and is not touched, that is, a “no tilt touch state”.
In the present embodiment, a state in which two or more pressure sensors 3 with a negative detection value difference rx are detected is determined as a “no tilt touch state”. This determination method is a content found by experimental results.

  Here, the detection value difference rx in the “no tilt touch state” should be zero, which is the same as the “no static touch state”, but varies and is not fixed due to the various reasons described above. Therefore, by constantly measuring the detection value difference rx and correcting the touch contact force T, it is possible to improve the position calculation accuracy of the touch coordinates.

Touch contact force T = Σ (detection value Rx−initial value Kx + correction value Ix) (2)
Next, the correction value measurement processing method in the present embodiment will be described. In this correction value measurement processing method, the correction value Ix of the above equation (2) is measured. Specifically, each pressure sensor 3 is constantly monitored by a timer interruption, and the detected value difference rx (Rx−Kx) in the “no tilt touch state” is measured a plurality of times, and the measurement result is set as a correction value Ix.

  In this correction value measurement process, the following conditions that prevent measurement value acquisition are assumed, and the correspondence is included.

(1) While the user is handling the touch panel so that the posture changes suddenly, the value of the pressure sensor 3 is very unstable. In such an unstable state, the measurement value is not used, and the measurement value is used as the correction value Ix while the measurement value is stable. This is realized by determining the correction value Ix in the correction value management unit 25 when the detected value difference rx in the “no tilt touch state” is the same value for a predetermined cumulative number of times and turning on the correction value determination flag.
(2) When the sensitivity of the pressure sensor 3 is very high, the value of the pressure sensor 3 always fluctuates slightly. Therefore, in the measurement value condition determination process, a threshold value is given and whether or not it is within a certain range. Is determined. The pressure sensor processing unit 24 does not adopt the value immediately after the start of measurement in reading by the A / D converter, reads the value into the buffer a predetermined number of times after a predetermined time, and uses the arithmetic average of these as the sensor value. Output.

  FIG. 5 is a flowchart showing an overall processing procedure for applying the touch position correction of the touch panel in the present embodiment. This processing procedure is executed by the coordinate management unit 26 of the force management block 20.

  This process is started each time the touch coordinates are required by the main management unit 21 of the force management block 20, and each detection value difference rx is acquired in step S01. In step S02, the correction value confirmation flag is referred to. When the correction value confirmation flag is on, in step S04, the correction value Ix is acquired in the case of confirmation, and in step S05, the touch coordinates are calculated based on the equation (2). Calculate the value.

  When the correction value confirmation flag is off, the correction value Ix is set to 0 in step S03, and the touch coordinate value is calculated in step S05.

  FIG. 6 is a diagram showing variable parameters and flags used in the correction value measurement processing of the touch panel in the present embodiment. The processing contents will be described below with reference to these variable parameters as appropriate.

  FIG. 7 is a flowchart showing a correction value measurement processing procedure. This processing procedure is executed by the correction value management unit 25 of the force management block 20.

  The correction value management unit 25 is activated in response to an activation interrupt from the timer processing unit 23 at a predetermined period (for example, 10 msec). In step S10, the correction value management unit 25 executes a “correction value confirmation flag clear process”. When the magnitude of the difference between the previous and current pressure sensor 3 values exceeds a predetermined threshold value, the fixed correction value Ix cannot be adopted. Therefore, in the “correction value confirmation flag clear process”, the confirmed correction value Ix is reset. The “correction value confirmation flag clear process” will be described later with reference to FIG.

  Next, the correction value management unit 25 measures a new correction value Ix based on the detection value difference rx of each pressure sensor 3 acquired via the pressure sensor processing unit 24 “Starts correction value measurement processing. .

  In step S11, it is determined whether or not the touch panel 10 is in the “no tilt touch state”. That is, this state is determined when a condition that there is at least two pressure sensors 3 with a detection value difference rx ≦ −1 (here, a predetermined threshold value 0 is set for ease of explanation) is established. Here, x is a subscript of 1 to 4 representing each pressure sensor 3 (the same applies hereinafter).

When the answer in step S11 is No, the touch panel 10 is in the “no stationary touch state” or is in a touched state, and thus the correction value measurement process is terminated.
When Yes in step S11, the state is “no tilt touch”, and therefore “correction value confirmation flag clearing process due to sensor value fluctuation” in step S12 is executed. This “correction value confirmation flag clearing process due to sensor value fluctuation” is performed when the detection value difference rx between the previous time and this time changes to a predetermined threshold value or more, so that the correction value measured so far cannot be adopted. Is the process of clearing. Details will be described later with reference to FIG.

  In step S13, it is checked whether the correction value is being measured. If the correction value is being measured, the correction value is measured and stored in the measured work value Wx during that period. Therefore, if the measured work value Wx is not 0, it is determined that the correction value is being measured.

If the measured workpiece values Wx (1 to 4) are all = 0 (No in step S13), the correction value is not being measured and preparation for measurement start is performed. In step S14, each counter is reset, and in step S15, the detected value difference rx is stored as the measured work value Wx, and the process ends.
If even one measured workpiece value Wx (1 to 4) is not 0 (Yes in step S13), the correction value is being measured. Therefore, in step S16, the current detected value difference rx and the measured workpiece value Wx are determined. It is determined whether they are equal (difference within a predetermined threshold). This is for detecting that the touch panel 10 is in a stable state.

  If the current detected value difference rx and the measured workpiece value Wx are not equal (No in step S16), 1 is added to the measurement error counter Q in step S17. In step S18, it is determined whether or not the measurement error counter Q has exceeded a predetermined maximum value.

  When the error count is continuously performed by the number of times exceeding the predetermined maximum value (Yes in Step S18), the measured work value Wx is cleared in Step S19, and the correction value measurement process is ended. If the number of consecutive error counts is less than or equal to the predetermined maximum value (No in step S18), the correction value measurement process is terminated.

  If the current detected value difference rx and the measured workpiece value Wx are substantially equal (difference within a predetermined threshold) (Yes in step S16), the measurement error counter Q is cleared in step S20. In step S21, 1 is added to the measurement counter Z.

  In step S22, it is determined whether or not the measurement counter Z has exceeded a predetermined maximum value (may be a value different from that in step S18).

When the measurement counter Z is less than or equal to the predetermined maximum value (No in step S22), the correction value measurement process is terminated.
When the measurement counter Z exceeds a predetermined maximum value (Yes in step S22), the measured work value Wx is adopted as the fixed correction value Ix in step S23. Here, for example, 20 is set as the maximum value of the count of the measurement counter Z. That is, when the reading period is 10 ms and the value for 0.2 seconds is stabilized, the measured work value Wx is adopted as the determined correction value Ix.

  In step S24, the measured workpiece value Wx is cleared. In step S25, the correction value confirmation flag F is turned on. Then, the correction value measurement process ends.

  According to the above processing, when a fixed correction value is obtained, the correction value determination flag F is turned on, and the correction value fixed for correction is stored in the correction value Ix. The determined correction value Ix is used as a correction value when the coordinate management unit calculates the coordinates of the touch position.

  FIG. 8 is a flowchart showing a schematic procedure of “the correction value confirmation flag clearing process when there is no stationary touch” in the present embodiment. This “fixed value determination flag clear process without stationary touch” is the process of step S10 in FIG. “No stationary touch correction value determination flag clear process” is a process in which the touch panel 10 detects “no static touch state” and clears each data and flag in the correction value determination state.

In step S31, it is determined whether or not the correction value determination flag F is on. When the correction value confirmation flag F is off (No in step S31), since the correction value is not confirmed, the “correction value confirmation flag clear process without stationary touch” is ended.
When the correction value confirmation flag F is on (Yes in Step S31), in Step S32, it is determined whether or not the touch panel 10 is in the “no stationary touch state”.

If the touch panel 10 is not in the “no static touch state” (No in step S32), the “no static touch touch correction value confirmation flag clear process” is terminated.
If it is “no stationary touch” (Yes in step S32), the subsequent processing is executed.

  In the processing from step S33 to step S34, the stationary touch-free transition counter M is counted up each time, and when the predetermined number of times is reached, it is determined that there is no stationary touch, and the correction value confirmation flag F is set in step S35. As the off, the fixed correction value Ix is cleared (set to zero).

  With the processing shown in FIG. 8, in the state without stationary touch, the coordinate management unit 26 calculates the touch coordinates with the correction value set to zero.

  FIG. 9 is a flowchart showing a schematic procedure of the “correction value confirmation flag clear process due to sensor value variation” in the present embodiment. This “correction value confirmation flag clear process due to sensor value fluctuation” is the process of step S12 in FIG.

  The “correction value confirmation flag clear process due to sensor value fluctuation” is a correction value for measuring the correction value Ix again when the detection value difference rx of the output value of the pressure sensor 3 greatly changes from the fixed correction value Ix. This is a process of initializing each data in the confirmed state.

  In step S41, it is determined whether or not the correction value determination flag F is on. If the correction value confirmation flag F is off (No in step S41), the correction value is not confirmed, and the correction value confirmation flag clear process due to sensor value fluctuation is terminated.

When the correction value confirmation flag F is on (Yes in step S41), it is determined in step S42 whether or not the state of the fixed correction value is maintained. This condition is determined by comparing the detected value difference rx with the determined correction value Ix (whether the values are substantially the same). In the present embodiment, the term “substantially the same” is the same within a range of ± 3. (Set the range value according to the characteristics of the device or circuit.)
When the state of the fixed correction value is maintained (Yes in step S42), this “correction value determination flag clear process due to sensor value fluctuation” is ended.
When the determined correction value state is not maintained (No in step S42), it is determined that the correction value has changed.

  In the subsequent processing from step S43 to step S44, when the fixed release counter B is incremented every time and reaches a predetermined number of times, the corrected correction value Ix is cleared by setting the correction value determination flag F to off in step S45. To do.

  As described above, since the correction method according to the present embodiment acquires correction values in a stable state of the touch panel, it is possible to obtain point coordinates with high user operability and high accuracy that do not fluctuate unnecessarily. Can be obtained.

  The correction is not limited to the above-described embodiment, and can be performed in various ways.

  Furthermore, each function can be realized by causing a computer to read a program stored in a recording medium (not shown). Here, as long as the recording medium in the present embodiment can record a program and can be read by a computer, the recording format may be any form.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display panel, 2 ... Cover panel, 3 ... Pressure sensor, 4 ... Pressure sensor control part, 10 ... Touch panel, 20 ... Force management block, 21 ... Main management part, 22 ... Communication part, 23 ... Timer processing part, DESCRIPTION OF SYMBOLS 24 ... Pressure sensor process part, 25 ... Correction value management part, 26 ... Coordinate management part, 28 ... Communication line, 30 ... Display processing block, 31 ... Main control part, 32 ... Communication part, 33 ... Drawing part.

Claims (5)

A touch position correction processing method of a touch panel comprising a substantially transparent cover panel to which a pressing force is applied and a plurality of pressure sensors for detecting the pressing force of the cover panel,
Determining whether external pressure is applied to the cover panel from the output value of the pressure sensor; and
A step of constantly measuring a difference between an output value of the pressure sensor when no pressing force is applied from the outside and a reference value of the pressure sensor and recording a difference in a stable state as a correction value;
Calculating the coordinates on the cover panel to which the pressing force is applied using the output value of the pressure sensor when the pressing force is applied from the outside and the recorded correction value, and
The touch position correction processing method, wherein the reference value is an output value of the pressure sensor in a state where the touch panel is left in a horizontal state and no external pressing force is applied.   2. The method according to claim 1, wherein when there is at least two pressure sensors in which a difference between an output value of the pressure sensor and a reference value of the pressure sensor is negative, it is determined that no pressing force is applied from the outside. The touch position correction processing method according to claim 1.   The touch position correction processing method according to claim 2, wherein in the stable state, the difference is substantially the same value a predetermined number of times or more.   4. The recorded correction value is cleared when a state where a difference between the recorded correction value and the measured correction value is equal to or greater than a predetermined threshold is equal to or greater than a predetermined number of times. Touch position correction processing method. A computer program for controlling a touch panel comprising a substantially transparent cover panel to which a pressing force is applied and a plurality of pressure sensors for detecting the pressing force of the cover panel,
On the computer,
Determining whether external pressure is applied to the cover panel from the output value of the pressure sensor; and
A step of constantly measuring a difference between an output value of the pressure sensor when no pressing force is applied from the outside and a reference value of the pressure sensor and recording a difference in a stable state as a correction value;
Calculating the coordinates on the cover panel to which the pressing force is applied using the output value of the pressure sensor when the pressing force is applied from the outside and the recorded correction value; and
The program according to claim 1, wherein the reference value is an output value of the pressure sensor in a state where the touch panel is placed in a horizontal state and no external pressing force is applied.

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