JP5219965B2 - Touch panel device - Google Patents

Description

  The present invention relates to a touch panel (touch screen) device, and more particularly, to a technique for detecting a touch position on a projected capacitive type touch panel.

  The touch panel is a user interface device in which an input device (touch pad) and an output device (flat panel display) are integrated. It is characterized by an intuitive operation method in which an operation target displayed on a display is directly touched with a finger or the like, and is widely used in information terminals and the like.

  There are various realization methods for touch panels, and one of them is a projection capacitive method. In this method, a plurality of electrodes are arranged on the panel, and the touch position is detected based on the change in capacitance of each electrode that occurs when the fingertip approaches the panel. A touch panel can be configured by using a material with high transmittance for the electrode and disposing it on the display panel.

  A touch panel performance index as an input device includes a touch position detection accuracy. The smaller the error between the position actually touched by the user on the panel and the detected position, the higher the accuracy.

  As an example of a technique for detecting a touch position with high accuracy in a projected capacitive touch panel, a method described in Patent Document 1 can be given. In this touch position detection method, the electrodes for detecting the positions in the X and Y directions are arranged so that the fingertip touches a plurality of electrodes at the same time (electrode pattern) at the time of touch. It is possible to ask.

  Further, in Patent Document 2, the manufacturing process can be simplified by using an electrode pattern that can form electrodes for detecting positions in the X and Y directions on a single layer.

Special table 2003-511799 gazette JP 2008-269297 A JP-A-10-020992

  However, in the conventional touch position detection method, when the range in which the fingertip touches the panel at the time of touch (touch area) protrudes from the area where the electrodes are arranged (electrode area), the accuracy of the detected touch position decreases. There is a problem. In order to prevent this, it is necessary to limit the effective range of touch position detection to a certain range inside the electrode region. For this reason, even if the electrodes are arranged on the entire panel, an area where the touch position cannot be detected is formed at the edge of the panel.

  The present invention is to solve the above-described problems, and its purpose is to detect the touch position with high accuracy even when the touch area protrudes from the electrode area, and thereby to detect the entire electrode area. It is to provide a touch panel having an effective range of touch position detection.

  In the present invention, the following two solutions are shown.

  In the first solution, the shape of the touch area is assumed to be a circle, for example. A width in the X direction and a width in the Y direction of a region where the touch region circle and the electrode region overlap are obtained from sensor measurement values. When the width in the X direction is different from the width in the Y direction, it is determined that the touch area protrudes from the electrode area, and the position of the center of the touch area circle is regarded as the touch position.

  In the second solution, when the signal value at the electrode at the panel end becomes the maximum, it is determined that the touch is on the peripheral portion of the panel. In the case of a touch on the panel periphery, an electrode position parameter value different from that in the case of a touch on the panel center is used in the calculation of the weighted average performed in the touch position calculation process. The calculated position is corrected by weighting the signal value of each electrode and changing the degree of weighting according to the touch size.

  Note that Patent Document 3 also shows means for detecting the touch position with high accuracy in a situation where the signal value of the electrode at the panel end is maximum, but the electrode position adjacent to the electrode at the end and the electrode at the other end The position is selected and the touch position is detected using the approximate quadratic curve, which is a completely different method from the present invention.

  According to the first solution, the touch position can be detected with high accuracy even when the touch area protrudes from the electrode area in either the X direction or the Y direction.

  According to the second solving means, the touch position can be detected with high accuracy even in the case of touching the peripheral portion of the panel by using the electrode for detecting the touch position in one direction.

It is a block diagram which shows the whole structure of the touchscreen module in 1st Embodiment. 4 is a cross-sectional view showing a cross-sectional structure of the touch panel 1. FIG. It is a flowchart which shows the procedure of a touch position detection process. It is a figure which shows the example of the sensor measured value in case a touch area | region has protruded from the electrode area | region. It is a figure which shows the calculation method of a touch position in case a touch area | region has protruded from the electrode area | region. It is a block diagram which shows the whole structure of the touchscreen module in 2nd Embodiment. It is a flowchart which shows the procedure of a touch position detection process. It is a figure which shows the example in case a touch position is a panel center part. It is a figure which shows the example in case a touch position is a panel peripheral part.

Hereinafter, examples of embodiments of the present invention will be described.
[First Embodiment]
FIG. 1 is a block diagram showing an overall configuration of a touch panel module (touch panel device) used in this embodiment. The touch panel module includes a touch panel 1, a capacitance detection unit 2, a control unit 3, a storage unit 4, and a bus connection signal line 5. The touch panel 1 is formed with electrode patterns (electrodes X1 to 5 and electrodes Y1 to 5) which are sensor terminals for detecting a user's touch. The electrostatic capacitance detection unit 2 is connected to the electrodes X1 to 5 and the electrodes Y1 to 5, and measures the electrostatic capacitance of each of the electrodes. The control unit 3 detects the touch position based on the measurement result of the capacitance, and notifies the host of the detection result via the bus connection signal line 5. The storage unit 4 stores the following parameters and work data necessary for the control unit 3 to perform the touch position detection process. The reference value 41, the measured value 42, and the difference value 43 are array data having the total number of electrodes as the number of elements. In this embodiment, the number of elements of the array is 10. The touch threshold value 44, the conversion ratio 45, the overlap width X46, and the overlap width Y47 are single numerical data.

  FIG. 2 is a cross-sectional view showing a cross-sectional structure of the touch panel 1. The touch panel 1 has a structure in which a substrate layer 13 is a bottom surface, and an electrode layer Y, an insulating layer 12, an electrode layer X, and a protective layer 11 are sequentially stacked.

  FIG. 3 is a flowchart illustrating a procedure of touch position detection processing.

  FIG. 4 is a diagram illustrating an example of sensor measurement values when the touch area protrudes from the electrode area.

  FIG. 5 is a diagram illustrating a method for calculating a touch position when the touch area protrudes from the electrode area.

  Hereinafter, a flow of processing for detecting a touch position will be described based on the flowchart of FIG.

  When the touch panel module is powered on, the following processing is started.

  In step S1, the control unit 3 initializes the reference value 41. Specifically, the capacitance is measured for each of all the electrodes (electrodes X1 to 5 and electrodes Y1 to 5), and the obtained value is stored as the reference value 41 of each electrode. The reference value 41 is a capacitance when each electrode is not touched. Here, it is assumed that the touch panel 1 is not touched when the power is turned on.

  In step S <b> 2, the controller 3 first measures the capacitance for each of all the electrodes, and stores the obtained value as the measured value 42 for each electrode. Further, the value obtained by the following equation (1) is stored as the difference value 43.

Difference value 43 = measured value 42−reference value 41 (1)
However, when the value obtained by the expression (1) becomes a negative value, 0 is stored as the difference value 43 instead. The difference value 43 is a capacitance increased by touching each electrode.

  Hereinafter, description will be made assuming that the obtained difference value 43 is in the state shown in FIG. 4, the upper diagram of the touch panel 1 is a graph showing an example of the difference value 43 and the touch threshold value 44 of the electrodes X1 to X5. The horizontal axis represents the electrodes X1 to X5, and the height of the bar graph represents the difference value 43. The difference value 43 between the electrodes X1 and X2 is greater than or equal to the touch threshold value 44, and the difference value 43 between the electrodes X3 to X5 is less than the touch threshold value 44. 4, the diagram on the right side of the touch panel 1 is a graph showing an example of the difference value 43 and the touch threshold value 44 of the electrodes Y1 to Y5. The horizontal axis represents the electrodes Y1 to Y5, and the height of the bar graph represents the difference value 43. The difference value 43 between the electrodes Y2 to Y4 is greater than or equal to the touch threshold value 44, and the difference value 43 between the electrodes Y1 and Y5 is less than the touch threshold value 44.

  In step S3, the control unit 3 determines whether or not the touch panel 1 is touched. Specifically, the difference value 43 of each electrode is compared with a preset touch threshold value 44. Here, in both the X-axis and the Y-axis, when the difference value 43 of at least one electrode is a value equal to or greater than the touch threshold value 44, it is determined that there is a touch and the process proceeds to step S4. If the condition is not satisfied, it is determined that there is no touch, and the process returns to step S2. In the state shown in FIG. 4, since the difference value 43 between the electrodes X1 and X2 and the electrodes Y2 to Y4 is a value equal to or greater than the touch threshold value 44, it is determined that there is a touch.

  In step S4, the control unit 3 stores the values obtained by the following equations (2) and (3) as an overlap width X46 and an overlap width Y47, respectively.

Overlap width X46 = MAX (Y-axis difference value 43) * conversion ratio 45 (2)
Overlap width Y47 = MAX (X-axis difference value 43) * Conversion ratio 45 (3)
Here, the function MAX is a function that selects and returns the maximum one from a plurality of values. In FIG. 4, the difference value 43 of the electrode X1 is maximum on the X axis, and the difference value 43 of the electrode Y3 is maximum on the Y axis. The conversion ratio 45 is a preset value, and is a ratio for converting the value of the difference value 43 into a length on the touch panel 1. As shown in FIG. 5, the overlap width X46 and the overlap width Y47 are respectively the X direction of the area where the touched area (touch area) on the touch panel 1 and the area where the electrode is arranged (electrode area 6) overlap. And the width in the Y direction.

  The reason why the overlap width X46 is obtained in Expression (2) is as follows. As can be seen from FIG. 4, since the electrode Y3 has the longest width in the X direction overlapping the touch area, the change in capacitance is the largest, and the difference value 43 is the largest as shown in the right figure. Since the width of the electrodes Y2 and Y4 in the X direction overlapping the touch area is shorter than that of the electrode Y3, the capacitance change is smaller than that of the electrode Y3, and the difference value 43 is smaller than the difference value of the electrode Y3 as shown in the right figure . Since the electrodes Y1 and Y5 have a slight width in the X direction overlapping the touch area, the change in capacitance is slight, and the difference value 43 is slight as shown in the right figure. Since the overlap width X46 is the width in the X direction of the area where the touch area and the electrode area 6 overlap, the overlap width X46 is the electrode Y3 which is the electrode having the longest width in the X direction overlapping the touch area. It is proportional to the width in the X direction, and is proportional to the difference value 43 of the electrode Y3. Therefore, the overlap width X46 is obtained by the equation (2). The conversion ratio 45 may be obtained by experiments or the like.

  The reason why the overlap width Y47 is obtained in Expression (3) is as follows. As can be seen from FIG. 4, since the electrode X1 has the longest width in the Y direction overlapping the touch region, the capacitance change is the largest, and the difference value 43 is the largest as shown in the upper diagram. Since the width of the electrode X2 in the Y direction overlapping the touch area is shorter than that of the electrode X1, the capacitance change is smaller than that of the electrode X1, and the difference value 43 is smaller than the difference value of the electrode X1 as shown in the upper diagram. Since the width of the electrode X3 in the Y direction overlapping the touch area is slight, the change in the capacitance is slight, and the difference value 43 is slight as shown in the upper diagram. Since the electrodes X4 and X5 do not have a width in the Y direction overlapping the touch area, there is no change in capacitance, and the difference value 43 is zero as shown in the upper diagram. Since the overlap width Y47 is the width in the Y direction of the region where the touch region and the electrode region 6 overlap, the overlap width Y47 is the electrode X1, which is the electrode having the longest width in the Y direction, overlapping the touch region. It is proportional to the width in the Y direction, and is proportional to the difference value 43 of the electrode X1. Therefore, the overlap width Y47 is obtained by the equation (3). The conversion ratio 45 may be obtained by experiments or the like.

  In step S5, the control unit 3 compares the values of the overlap width X46 and the overlap width Y47. If the difference between the two is smaller than the predetermined threshold, it is determined that the entire touch area is within the electrode area 6, and the process proceeds to step S6. Otherwise, the process proceeds to step S7.

  In step S6, the touch position is obtained based on the difference value 43. Specifically, for each of the X axis and the Y axis, a weighted average is obtained when the difference value 43 is the weight wi and the position of each electrode is xi, yi. That is, the following equations (4) and (5) are calculated.

Touch position (X coordinate) = Σ (wi * xi) / Σ (wi) (4)
Touch position (Y coordinate) = Σ (wi * yi) / Σ (wi) (5)
Thus, one cycle of touch position detection when the touch area does not protrude from the electrode area 6 is completed, and the process returns to step S2.

  In step S7, it is assumed that the shape of the touch area is a circle, and the center position of the circle is regarded as the touch position for calculation. Here, it is assumed that the touch region protrudes from the electrode region 6 in the X direction as shown in FIG. At this time, the X coordinate of the touch position is obtained by the following equation (6).

Touch position (X coordinate) = overlap width X46−overlap width Y47 / 2 (6)
In FIG. 5, X corresponds to the X coordinate, and R corresponds to the overlap width Y47 / 2. The Y coordinate is obtained by the calculation formula (5) when the touch area does not protrude from the electrode area 6. When the touch area protrudes from the electrode area 6 in the Y direction, the touch position can be obtained in the same manner by exchanging X and Y in the above calculation method.

  As described above, one cycle of the touch position detection when the touch area protrudes from the electrode area 6 is completed, and the process returns to step S2.

  In the above description, it is assumed that the shape of the touch area is a circle. However, in this case, if the touch position can be calculated based on the overlap width X46 and the overlap width Y47, this embodiment is applied. it can. That is, the width in the X direction and the width in the Y direction of the area where the touch area and the electrode area overlap is obtained, the position of the center of the touch area is obtained from the obtained width in the X direction and the width in the Y direction, and the position of the center is determined. What is necessary is just to calculate as a touch position. The shape of the touch area can be assumed to be an arbitrary figure. For example, it may be assumed that it is a circle or an ellipse, or it is assumed that the ratio of the width in the X direction to the width in the Y direction is constant (for example, a square or rectangle or a square or rectangle with rounded corners). May be. Further, the shape of the touch area may be determined by experiments or the like.

[Second Embodiment]
Next, the second embodiment will be described. Hereinafter, the same components as those described in the above embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 6 is a block diagram showing the overall configuration of the touch panel module used in this embodiment. Unlike the first embodiment, the storage unit 4 stores a touch size 48 and a weighting value 49 in addition to the reference value 41, the measurement value 42, the difference value 43, and the touch threshold value 44 described above. The touch size 48 is a single numerical data. The weighting value 49 is single or plural numerical data.

  FIG. 7 is a flowchart illustrating the procedure of the touch position detection process.

  FIG. 8 is a diagram illustrating an example when the touch position is at the center of the panel.

  FIG. 9 is a diagram illustrating an example in a case where the touch position is the peripheral portion of the panel.

  Hereinafter, the flow of processing for detecting a touch position will be described with reference to the flowchart of FIG.

  When the touch panel module is powered on, the following processing is started.

  Since the processing contents of steps S11 to S13 are the same as those of steps S1 to S3 in the first embodiment, description thereof is omitted.

  In step S <b> 14, the control unit 3 obtains the sum of the difference values 43 of all the electrodes, that is, the electrodes X <b> 1 to 5 and the electrodes Y <b> 1 to 5, and stores them as the touch size 48. The touch size 48 is a value proportional to the area of the touch area, and is notified to the host together with the touch position detected by the following steps as an index indicating the strength of the touch. The reason why the touch size (value proportional to the area of the touch area) is obtained by the sum of the difference values 43 of all the electrodes is as follows. For example, in FIG. 8, the difference value 43 of the electrode X1 is proportional to the area of the area where the electrode X1 and the touch area overlap, and the difference value 43 of the electrode X2 is proportional to the area of the area where the electrode X2 and the touch area overlap. The difference value 43 is proportional to the area of the area where the electrode X3 and the touch area overlap, the difference value 43 of the electrode X4 is proportional to the area of the area where the electrode X4 and the touch area overlap, and the difference value 43 of the electrode X5 is the touch of the electrode X5. It is proportional to the area of the overlapping region. The same applies to the electrodes Y1 to Y5. Therefore, a touch size (a value proportional to the area of the touch region) can be obtained by summing the difference values of all the electrodes. In this embodiment, the touch size is obtained in this way, but the touch size may be obtained by other methods.

  Hereinafter, the procedure for detecting the touch position in the X direction will be described. The touch position in the Y direction can also be detected by the same procedure.

  In step S15, the control unit 3 determines whether or not the detected touch is a touch on the panel peripheral portion. Specifically, when the difference value 43 of any electrode at the panel end, that is, the electrode X1 or X5 takes the maximum value, it is determined that the touch is on the peripheral portion of the panel, and the process proceeds to step S17. If the condition is not satisfied, it is determined that the touch is not on the peripheral portion of the panel (touch on the center portion of the panel), and the process proceeds to step S16. For example, in the situation shown in FIG. 8, since the difference value 43 of the electrode X2 that is not the panel end is the maximum, it is determined that the touch is not on the peripheral portion of the panel. In the situation shown in FIG. 9, since the difference value 43 of the electrode X1 at the panel end is the maximum, it is determined that the touch is on the peripheral portion of the panel.

  In step S <b> 16, the control unit 3 obtains a touch position based on the difference value 43 of each electrode as a coordinate calculation process in the case of touching the panel center. Specifically, a weighted average is obtained when the difference value 43 of each electrode is set to the weight wi and the position of each electrode is set to xi. That is, the following equation (7) is calculated.

Touch position = Σ (wi * xi) / Σ (wi) (7)
Here, the electrode position xi is a coordinate value of the center of each electrode. In the situation shown in FIG. 8, the electrode positions xi of the electrodes X1 to X5 are 0.5, 1.5, 2.5, 3.5, and 4.5 in order. Thus, one cycle of the touch position detection process is completed, and the process returns to step S12.

  In step S <b> 17, the control unit 3 performs the touch based on the difference value 43 between the electrode having the maximum difference value 43 and the adjacent electrodes (panel end two electrodes) as coordinate calculation processing in the case of touching the panel peripheral part. Find the position. Specifically, as in step S16, the calculation of Expression (7) is performed based on the panel end two electrodes. However, the difference is that the electrode position xi, that is, the parameter value of the sensor position is used as the coordinate value of both ends of the two electrodes. In the situation shown in FIG. 9, the position of the electrode X1 is 0, and the position of the electrode X2 is 2. The calculation formula in this case is the following formula (8) in which the electrode positions x1 = 0 and x2 = 2 are substituted for the two electrodes at the panel end in formula (7).

  Touch position = 2 * w2 / (w1 + w2) (8)

  In equation (8), the reason why the coordinate values (x1 = 0, x2 = 2) of both ends of the two electrodes are selected as the electrode position is that the calculated touch is obtained when the difference value 43 is measured only by the electrode X1. When the position is 0 (panel end) and the difference value 43 between the electrode X1 and the electrode X2 is equal, that is, when w1 = w2, the calculated touch position is 1 (intermediate position between the electrodes X1 and X2). It is to make it. For example, in FIG. 9, assuming that the difference value w1 = 1 of the electrode X1 and the difference value w2 = 0.4 of the electrode X2, the touch in the present embodiment (x1 = 0, x2 = 2) calculated using the equation (8). The position is 0.57. On the other hand, the touch position calculated using Expression (7) with the electrode position of the two electrodes at the panel edge as the position coordinates (x1 = 0.5, x2 = 1.5) of the center of each electrode is 0.79. It is clear from FIG. 9 that the touch position 0.57 calculated in this embodiment is closer to the actual touch position than the touch position 0.79 calculated using the position coordinates of the center of each electrode.

  Thus, one cycle of the touch position detection process is completed, and the process returns to step S12.

  In step S15, the condition for determining that the touch is on the peripheral portion of the panel is that the difference value 43 of the electrode at the panel end is the maximum, but other conditions may be used. For example, the sum of the difference values 43 in the electrode at the panel end and a predetermined number of electrodes adjacent thereto may be larger than the sum of the difference values 43 in the other electrodes.

  In step S17, the reference electrode is the two electrodes at the panel end, but a method of referring to three or more electrodes is also conceivable. In addition, although the electrode position xi in the weighted average calculation is set to both ends of the two electrodes, other settings may be used. These are determined by design matters such as the assumed size of the touch area and the width of the electrodes.

  Although the present embodiment has been specifically described above, the touch panel device according to the present embodiment is a sensor position parameter value used in coordinate calculation processing (in the above example, electrode positions x1 and x2) in the case of touching the periphery of the panel. As a characteristic, a value different from that in the case of touching the center of the panel is used.

[Third Embodiment]
Next, the third embodiment will be described. In this embodiment, the coordinate calculation formula in step S17 in the second embodiment is changed.
In the present embodiment, in the case of touching the peripheral portion of the panel, each electrode referred to in coordinate calculation is weighted in order to reduce a deviation (error) between the actual touch position and the calculated touch position. Various weighting methods can be considered. One example is a method of multiplying the difference value 43 (wi) of each electrode by a predetermined weighting coefficient ai in equation (7). That is, the following equation (9).

Touch position = Σ (ai * wi * xi) / Σ (ai * wi) (9)
In the equation (9), as in the second embodiment, the electrode position xi for the two electrode at the panel end is set to the coordinate values of both ends of the two electrodes, that is, x1 = 0 and x2 = 2, 10).

Touch position = 2 * a2 * w2 / (a1 * w1 + a2 * w2) (10)
The values of a1 and a2 are predetermined values and are stored as weighting values 49. What is necessary is just to obtain | require the value of a1 and a2 by experiment.

  As another example, a method of calculating the following equation (11) in which the difference value 43 (w2) of the electrode X2 is weighted based on the equation (8) can be considered.

Touch position = (1 + a) * w2 / (w1 + a * w2) (11)
Here, a is a predetermined value and is stored as a weighting value 49. The coefficient in the numerator is 1 + a so that when the difference value 43 between the electrodes X1 and X2 is equal, that is, when w1 = w2, the calculated touch position is 1 (intermediate position between the electrodes X1 and X2). It is to do. The value of a (weighting value 49) may be obtained by experiments or the like.

[Fourth Embodiment]
Next, the fourth embodiment will be described. This embodiment adds a change to 3rd Embodiment.

  In the third embodiment, the degree of weighting for each electrode is a preset constant. However, the appropriate degree of weighting is not constant and may vary depending on the strength of the touch. In this embodiment, the degree of weighting is used as a variable and is changed according to the touch size 48. There are various methods for changing the degree of weighting. For example, in the calculation of Expression (11), the value of the weighting value 49 is changed according to the touch size 48. A predetermined function is used to obtain the weight value 49. When the function is a linear function of the touch size 48, the following equation (12) is obtained.

Weighting value 49 = b * touch size 48 + c (12)
Here, b and c are predetermined values. The values of b and c may be obtained by experiments or the like.

  In the above description of each embodiment, the left end of the touch panel has been described as an example. However, the touch position of the peripheral portion can be calculated with high accuracy in the same manner at the right end, upper end, and lower end of the touch panel.

  In the first embodiment, detection is performed using both electrodes in the X direction and the Y direction. Therefore, in the panel peripheral portion in one direction of the X direction or the Y direction, that is, the panel peripheral portion not including the corner portion of the touch panel. The touch position can be detected with high accuracy. On the other hand, in the second to fourth embodiments, since the detection is performed using the electrodes in one direction (X direction or Y direction), the touch position can be detected with high accuracy in the peripheral portion of the panel including the corners. .

  In addition, this invention is not limited to the Example described above, Of course, it can change variously in the range which does not deviate from the summary.

DESCRIPTION OF SYMBOLS 1 Touch panel 11 Protective layer 12 Insulating layer 13 Substrate layer X, Y Electrode layer X1-5 Electrode (X axis)
Y1-5 electrodes (Y axis)
2 Capacitance detection unit 3 Control unit 4 Storage unit 5 Bus connection signal line 6 Electrode region

Claims (4)

In a touch panel device that detects a touch position based on measurement values of a plurality of sensors, an area in which a touch area and an electrode area overlap based on sensor measurement values for detecting a touch position in the X direction and a touch position in the Y direction The width in the X direction and the width in the Y direction are obtained, and when the difference between them is not smaller than a predetermined threshold, the center position of the touch area is obtained from the width in the X direction and the width in the Y direction, and the center If the difference between the two is not smaller than a predetermined threshold, the touch position in the first direction is determined as the first position of the region where the touch region and the electrode region overlap. and calculates a value obtained by subtracting one-half of the second width of the region from the first width overlaps with the touch area and the electrode area, Tatchipane Apparatus.   The touch panel device according to claim 1, wherein the touch area is assumed to have a constant ratio between a width in the X direction and a width in the Y direction.   The touch panel device according to claim 1, wherein a shape of the touch area is assumed to be a circle or an ellipse.   The width in the X direction of the region where the touch region and the electrode region overlap is obtained by multiplying the maximum value of the Y-axis sensor measurement value by a preset value, and the Y of the region where the touch region and the electrode region overlap is obtained. 2. The touch panel device according to claim 1, wherein the direction width is obtained by multiplying a maximum value of sensor measurement values on the X axis by a preset value.

Images