TWI433021B - Method for setting driving signals for electrode of touch panel and driving method for touch panel - Google Patents

Description

Touch screen electrode driving signal setting method and touch screen driving method

The present invention relates to a method for setting a touch screen electrode driving signal and a driving method for the touch screen, and more particularly to a method for setting a capacitive touch screen electrode driving signal and a driving method of the capacitive touch screen.

In recent years, with the development of high performance and diversification of various electronic devices such as mobile phones and touch navigation systems, electronic devices in which a translucent touch panel is mounted on the front surface of a display device such as a liquid crystal are gradually increasing. The user of such an electronic device visually confirms the display content of the display device located on the back surface of the touch panel by the touch panel, and presses the touch panel to operate by a finger or a pen. Thereby, various functions of the electronic device can be operated.

According to the working principle of the touch screen and the transmission medium, the existing touch screens include four types, namely, resistive, capacitive, infrared, and surface acoustic wave. Among them, the capacitive touch screen is widely used due to its high accuracy and strong anti-interference ability.

In the prior art, the driving mode of the capacitive touch screen is: the integrated circuit (IC) sequentially drives each electrode of the touch screen with the same driving signal, and sequentially reads the capacitance of each electrode in turn, after receiving the touch signal, the IC The touch point is detected based on the change in capacitance after the touch. However, due to the impedance generated by the wires connected to the electrodes and the presence of parasitic capacitance, it is easy to cause the touch point to be erroneously detected or the detection accuracy is lowered.

In view of the above, it is necessary to provide a method of setting a touch screen electrode driving signal capable of improving touch precision and a driving method of the touch panel.

A method for setting a touch screen electrode driving signal, comprising the following steps: powering Each of the electrodes of the capacitive touch screen respectively provides a changed driving signal; reading an initial capacitance value set of each electrode under the changed driving signal when the touch screen is not touched; setting a basic capacitance value by using Comparing the basic capacitance values, selecting an initial capacitance value closest to the basic capacitance value from the initial capacitance value set of each electrode, and setting a driving signal value corresponding to the initial capacitance value in the changed driving signal as the electrode The best drive signal value.

A driving method of a touch screen, comprising the steps of: respectively providing a driving voltage to a driving electrode of the touch screen, wherein a driving voltage of each electrode selects an optimal driving signal value according to the above method; and touching the touch screen with a touch conductor to make a touch position The capacitance changes; the sensing electrodes of the touch screen are measured, the sensing signals output by the sensing electrodes are read, and the sensing signals are analyzed to determine the touch point position.

Compared with the prior art, the present invention sets the optimal driving signal value of each electrode by adjusting the initial capacitance value of each electrode of the capacitive touch screen to the same value. That is, each electrode corresponds to a different optimal driving signal value. Generally, the electrode at the far end of the IC conductive path is driven by a larger driving signal, and the electrode at the proximal end of the IC conductive path is driven by a smaller driving signal. Therefore, after the touch, the capacitance of each electrode starts to change from the value of the basic capacitance, thereby ensuring that the changed capacitance value is still within the range set by the IC, and the variation of the capacitance value in the range is large, so that the touch can be detected more accurately. point. Can be applied to a variety of capacitive touch screens.

Hereinafter, a method for setting a touch screen electrode driving signal and a driving method of the touch screen according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The touch screen of the present invention is suitable for a capacitive touch screen, and firstly introduces a capacitive touch screen to which the present invention is applicable:

Structurally speaking, the capacitive touch screen has at least one transparent conductive layer, a plurality of electrodes that are spatially isolated from each other and electrically connected to the transparent conductive layer, and one or more integrated circuits electrically connected to each of the electrodes by wires ( IC). The IC provides a driving signal to the electrode and detects a change in capacitance of the transparent conductive layer by the electrode to determine whether the touch screen surface has a touch and a position of the touch point.

The material of the transparent conductive layer may be indium tin oxide (ITO) or a carbon nanotube. The IC includes a driving IC and a sensing IC, and the driving IC provides a driving signal to the electrode; the sensing IC reads, by the electrode, a capacitance value when the touch screen is not touched and touched. In the embodiment of the invention, the capacitive touch screen adopts an IC, which has the functions of the driving IC and the sensing IC. In addition, the IC may be a single IC or a plurality of ICs that provide a driving function and a reading function in a conventional capacitive touch screen.

In principle, the method for setting the touch screen electrode driving signal of the present invention is only a process of providing, reading and scanning the signal between the IC and the touch screen electrode to find the optimal driving signal of the electrode. Therefore, the method is known to the prior art. Both surface capacitive touch screens and projected capacitive touch screens are suitable.

The method for setting the touch screen electrode driving signal of the present invention will be described below.

Referring to FIG. 1 , an embodiment of the present invention provides a method for setting a touch screen electrode driving signal. The method includes the following steps: Step 1: providing a changed driving signal to each electrode of the capacitive touch screen; and step 2, reading the The initial capacitance value set of each electrode under the changed driving signal when the touch screen is not touched; in step 3, a basic capacitance value is set, and the initial capacitance of each electrode is compared by comparing with the basic capacitance value The initial value of the value set closest to the base capacitance value The value of the capacitor is set to the optimum driving signal value of the electrode corresponding to the initial driving value of the changed driving signal.

In the above step 1, the changed driving signal is provided by an IC electrically connected to the electrode by a wire, and the IC can sequentially provide the changed driving signal to each electrode (in turn driving each electrode of the touch screen) It is also possible to provide a varying drive signal to all of the electrodes simultaneously (while driving each electrode of the touch screen). In the embodiment of the invention, an IC is used to sequentially drive each electrode of the touch screen, and the IC has the functions of a driving IC and an inductive IC. The changed driving signal can be a current or voltage signal that changes with time, such as a current pulse signal. In the embodiment of the present invention, the changed driving signal is a current signal that changes from small to large over time.

In the above step two, the IC reads the initial driving value when the electrode is not touched while providing the changed driving signal to each electrode of the touch screen. Due to the change of the driving signal, the initial capacitance value of the read electrode is also a set consisting of a set of varying capacitance values. The initial capacitance value of the electrode has different definitions for different capacitive touch screen structures. For example, when the touch screen has only a single transparent conductive layer for touch sensing, the initial capacitance value may be electrically connected to the transparent conductive layer. The capacitance value between the electrode and the ground; when the touch screen has two transparent conductive layers for touch sensing, the initial capacitance value may be a capacitance between each pair of corresponding electrodes electrically connected to the two transparent conductive layers respectively value. When the touch screen is touched, the initial capacitance value changes, and the IC reads the change of the initial capacitance value of each electrode to detect the touch point. Each initial capacitance value in the initial capacitance value set corresponds to each of the driving signal values in the changed driving signal.

The above step 2 may further comprise the steps of reading the average capacitance value set of each electrode under the changed driving signal and taking an average value.

The IC may provide the same driving signal of the change to the plurality of electrodes for a plurality of times, thereby reading the initial capacitance value set plural times, and averaging the initial capacitance value sets of the plurality of readings, that is, The initial capacitance values of the plurality of readings are averaged corresponding to the complex initial capacitance values of the same driving signal value as the initial capacitance value set when the electrodes are not touched. The process of reading the initial capacitance value set of each electrode and taking the average value can obtain a more accurate initial capacitance value set of each electrode, which facilitates accurate setting of each electrode driving signal described later.

In the above step three, the selection of the basic capacitance value is related to the IC, and the IC generally has an optimal reading range of the capacitor, and within the range, the capacitive touch screen is detected before and after being touched. The change in the capacitance value of the electrode is relatively large, which facilitates the detection of the touch point. In the embodiment of the present invention, a capacitance value with a large capacitance change before and after the touch is selected as the basic capacitance value. Referring to FIG. 7, the absolute value of the tangent slope of the initial capacitance value curve is generally selected to be equal to one location. The initial capacitance value is used as the base capacitance value, and the amount of change in the capacitance value is large and linearly changed near the initial capacitance value, which facilitates the calculation of subsequent touch point coordinates. Based on the value of the base capacitance value, an initial capacitance value closest to or equal to the base capacitance value is respectively found in the initial capacitance value set of each of the electrodes read, and the changed driving signal is compared with the initial capacitance value. The corresponding drive signal value is set to the optimal drive signal value of the electrode.

Step 2 and step 3 above may also be performed simultaneously, that is, the initial capacitance value is compared with the basic capacitance value while reading the initial capacitance value when each electrode is not touched, and the closest to the basic capacitance value is selected. The initial capacitance value of the electrode may be stopped when the initial capacitance value of the electrode closest to or equal to the base capacitance value is found.

Due to the impedance generated by the wires connected to the electrodes and the presence of parasitic capacitance, the initial capacitance values read by the IC may be different under different driving signal values. Generally, the initial capacitance value of the electrode longer from the IC conductive path is larger, and the initial capacitance value of the electrode shorter than the IC conductive path is smaller, and the unevenness of the capacitance value may cause the touch screen to be touched before and after being touched. The change in the capacitance value read by the IC from some electrodes is small or varies so as to exceed the optimal reading range of the IC, which may easily cause inaccurate or false detection of touch point detection. Therefore, in the embodiment of the present invention, the initial capacitance value of each electrode is set to be the closest or equal value to the basic capacitance value, and the driving signal value corresponding to the initial capacitance value is used as the optimal driving of the electrode. Signal value. When the touch screen is in operation, driving the electrodes of the touch screen with the driving signal having the optimal driving signal value, so that when the capacitive touch screen is touched, the initial capacitance values of all the electrodes are from the basic capacitance value or The closest value of the base capacitance value begins to change, so that the capacitance value after the change is ensured to be within the capacitance reading range set by the IC, and the change is large, which facilitates more accurate detection of the touch signal. From another point of view, the initial capacitance value of each electrode is set to the same level (base capacitance value), and the corresponding optimal driving signal value of each electrode is no longer the same: generally, the distance The electrode with a shorter IC conductive path is driven by a smaller optimal driving signal value, and the electrode longer from the IC conductive path is driven by a larger optimal driving signal value, thereby reducing or eliminating the The wire impedance of the electrode connection and the initial capacitance value of each of the electrodes caused by the parasitic capacitance are uneven, which facilitates accurate detection of the touch point.

Referring to FIG. 2, the optimal driving signal value of each of the electrodes in the above step 3 can be determined by the following steps: S11, setting a natural number set and a tolerance range of the basic capacitance value, wherein, The value of the natural number set is sequentially corresponding to the driving signal value that changes from small to large, and the capacitance value corresponding to the driving signal value is an initial capacitance value; S12, the selection range is confirmed in the natural number set, and Selecting a value from the selected range and reading the initial capacitance value corresponding to the value; S13, comparing the initial capacitance value corresponding to the value with the basic capacitance value, and determining whether the initial capacitance value is at the basic capacitance value Within the tolerance range; S14, when the initial capacitance value is within the tolerance range of the basic capacitance value, setting the driving signal value corresponding to the selected value to the optimal driving signal value of the electrode; When the initial capacitance value is not within the tolerance range of the basic capacitance value, the process returns to step S12, the selection range is re-determined within the natural number set, and the value in the natural number set is continuously selected within the range.

In the above step S11, the driving signal values in the natural number set and the changed driving signal are sequentially corresponding from small to large. It can be understood that the larger the natural number set, that is, the more the value in the natural number set, the higher the precision corresponding to the driving signal value. The natural number set can be arbitrarily selected: if the natural number set can take all natural numbers from 0 to 100, or can be selected in a certain way: for example, select an even set between 50 and 200, or select (0~2 ^t) All the values in -1) are natural number sets, and t can be arbitrarily selected. The larger t is, the higher the precision of the natural number set corresponding to the driving signal value. The corresponding manner may have a plurality of types, for example, the value in the natural number set may be correspondingly proportional to the driving signal value that varies from small to large, proportionally corresponding, or the value in the natural number set may be used as the corresponding driving signal. The value of the digital signal value. In the embodiment of the present invention, the natural number set is {0, 1, 2, ... 2 ^t -1}, and the value in the natural number set is used as the digital signal value of the driving signal value in the changed driving signal.

The tolerance range of the basic capacitance value is corresponding to the driving signal value of the electrode The extent to which the initial capacitance value is close to the base capacitance value. The tolerance range may be set to an allowable range of an absolute value or a ratio of the difference between the initial capacitance value and the base capacitance value. It can be understood that the tolerance range can also have other setting manners, and the purpose is to ensure that the initial capacitance value corresponding to the driving signal value of the electrode can be closer to the basic capacitance value.

In the above step S12, in order to find the optimal driving signal value of the electrode, it may be necessary to perform the process of selecting the numerical value in multiple times. When multiple selections are required, the selection is based on the previous selection range. , thereby narrowing the selected range to quickly determine the optimal driving signal value of the electrode. Specifically, the first selection range is the entire natural number set, and a value is arbitrarily selected in the natural number set. For the determination of the subsequent specific selection range, refer to the introduction in step S14.

In the above step S12, the value can be arbitrarily selected within the natural number set. Since the value corresponds to a driving signal value, an appropriate selection method can quickly and accurately find the optimal driving signal value of the electrode. . If the value of the center value (1/2), 1/3 or 1/4 of the natural number set is selected, the center value of the natural number set is selected in the embodiment of the present invention. The value of the natural number set and the initial capacitance are obtained because the value of the natural number set corresponds to the driving signal value in the changed driving signal, and the corresponding initial capacitance value is readable according to the driving signal value. The values also correspond to each other. Comparing the initial capacitance value corresponding to the selected value with the basic capacitance value to find the optimal driving signal value of the electrode or further narrowing the range of the optimal driving signal value of the electrode.

In the above step S14, the re-determining the selection range may further include: when the initial capacitance value is less than the basic capacitance value, the next time the value is selected from the lower limit value of the current selection range to The value selected this time; when stated When the initial capacitance value is greater than the basic capacitance value, the next time the value is selected from the current selected value to the upper limit value of the selection range.

In the step S14, when there are multiple comparisons, each time the reselected selection range is based on the previous selection range, the selection range is further narrowed until the selected capacitance corresponding to the initial capacitance value is on the basis. The comparison is ended within the tolerance of the capacitance value. In addition, the reselected selection range in this step is the selected range of the confirmation in step S12 in the next cycle.

Referring to FIG. 3, the method for setting the optimal driving signal value of each electrode according to the embodiment of the present invention is as follows: S21, setting a natural number set to 0~(2 ^t -1), t is a natural number, and the natural number is concentrated. The value of the drive signal corresponds to the value of the drive signal that is changed from small to large for the touch screen electrode, and the capacitance value corresponding to the drive signal value is an initial capacitance value; S22, the selected range is confirmed in the natural number set, and the selected range is within the selected range. Selecting a center value of the natural number set, and reading an initial capacitance value corresponding to the center value; S23, comparing the initial capacitance value with the base capacitance value, determining whether the initial capacitance value and the basic capacitance value are equal; S24, When the initial capacitance value is equal to the basic capacitance value, the driving signal value corresponding to the center value is set as the optimal driving signal value of the electrode. When the initial capacitance value is not equal to the base capacitance value, the process returns to step S22, the selection range is reconfirmed, and the center value of the natural number set is selected within the selection range.

In the above step S21, the embodiment of the present invention selects the natural number set as (0~2 ^t -1), and the natural number set can be selected according to the precision of the analog-to-digital conversion module of the touch screen (not shown in the drawing) ), that is, the natural number t can be the precision of the analog to digital conversion module. Of course, the selection of the natural number set can also be independent of the accuracy of the analog to digital conversion module. It can be understood that the larger t is, the higher the precision of the corresponding value of the natural number set and the drive signal value that changes from small to large. In the embodiment of the present invention, t=8 is selected, that is, the natural number set is 0~255, and the driving signal from small to large is a current signal whose value changes from small to large, and the value of the natural number set is corresponding to the small one. The analog-to-digital converted digital signal value of the current value in the greatly varying current signal.

In the above step S22, the center value of the corresponding natural number set is selected each time, and the selection manner can quickly narrow the range of the optimal driving signal value of the electrode. And before selecting, it is necessary to confirm the selection range of the central value. It can be understood that the first selection range is the entire natural number set (0~2 ^t -1), and each subsequent selection of the selected range is determined. There is a specific introduction in step S24, which will not be described in detail herein. It has been mentioned in the above method that the natural number set, the driving signal from small to large, and the initial capacitance value set corresponding to the driving signal have a corresponding relationship, so that the selected central value can be directly or indirectly The initial capacitance value corresponding to the center value is read.

In the above step S24, the reselecting the selection range of the center value may further include: when the initial capacitance value is less than the basic capacitance value, the next selection of the center value is: from the lower limit of the current selection range The value is up to the center value of the current selection; when the initial capacitance value is greater than the base capacitance value, the next center value is selected from the center value selected this time to the upper limit value of the current selection range.

In the process of redetermining the selection range of the center value, the range of the optimal driving signal value of the electrode is gradually reduced, so that the optimal driving signal value of the electrode can be found more quickly. The selection range of the reconfirmation in step S24 is the selection range confirmed in step S22 in the next cycle.

To further illustrate the process selected in the method, please refer to FIG. 4, which illustrates a process for finding the optimal driving signal value of the electrode according to an embodiment of the present invention. As shown As shown, the natural number set is 0~255, and the first selected center value is A1=127. When the initial capacitance corresponding to the center value is less than the base capacitance value, the new selection range becomes the value in M1. A new natural number set is formed, and a center value A2=63 is selected in the natural number set range M1. When the initial capacitance value corresponding to the center value is greater than the base capacitance value, the new selection range becomes a value in M2. A new set of natural numbers is formed, and then the center value A3=31 is selected in the natural number set range M2, and the initial capacitance value corresponding to the center value and the base capacitance value are continuously compared. That is, the selection range is based on the previous selection range, and the range between the initial capacitance value and the basic capacitance value is further narrowed in the process of the cycle, so that the electrode can be found more quickly and accurately. The best drive signal value.

In the above step S24, the number of times of reselecting the center value when the initial capacitance value is not equal to the base capacitance value may be further set to k, and it is determined whether the number of times of the selection reaches k times: if not obtained k times, Re-determining the selection range of the center value, and returning to step S22 to continue the selection; if k times, the driving signal value corresponding to the k-th selected value is set as the optimal driving signal value of the electrode.

The step of setting the number of selections can shorten the time for setting the optimal driving signal value of the electrode. The number of selections k may have a corresponding relationship with the natural number set (0~2 ^t -1), such as k=t, or two separate parameters. It can be understood that the larger the value of k is, the better the optimal driving signal value of the last set electrode is, that is, the initial capacitance value corresponding to the optimal driving signal is closer to the basic capacitance value.

In the embodiment of the present invention, the time of the optimal driving value of the electrode is shortened by selecting the center value of the natural number set and setting the number of cycles.

In the above method, the tolerance range of the base capacitance value may also be set, and when the initial capacitance value is not equal to the base capacitance value, but the tolerance range of the basic capacitance value is The corresponding driving signal value is also set as the optimal driving signal value of the electrode. Therefore, the time for finding the optimal driving signal value is further shortened under the condition that the optimal driving signal value of the electrode is good.

Referring to FIG. 5 and FIG. 6 , the embodiment of the present invention specifically uses a single transparent conductive layer surface capacitive touch screen 100 . The touch screen 100 includes a substrate 102 , a conductive film 104 disposed on the substrate 102 , and a plurality of An electrode 106 and a plurality of second electrodes 108. The conductive film 104 has an impedance anisotropy to define a low-impedance direction D and a high-impedance direction H perpendicular to each other on the surface of the conductive film 104. The opposite sides of the conductive film 104 along the low-impedance direction D are respectively The first side 111 and the second side 112. The plurality of first electrodes 106 are spaced apart from each other along the first side 111, and the plurality of second electrodes 108 are spaced apart from each other along the second side 112. One ends of the plurality of first electrodes 106 and the plurality of second electrodes 108 are electrically connected to the conductive film 104, respectively, and the other ends are electrically connected to the IC 120 by wires 122, respectively. The first electrode 106 and the second electrode 108 are both a driving electrode and a sensing electrode, that is, the IC 120 provides a driving signal to the first electrode 106 and the second electrode 108 of the touch screen 100, and the driving signal is from the first electrode 106. And the second electrode 108 reads the sensing signal when the touch screen 100 is touched and untouched, and the sensing signal can be one or more of a capacitive signal, a voltage signal, a current signal, and a resistance signal. FIG. 5 is only a schematic diagram. There may be other components between the touch screen 100 and the IC 120 to ensure that the touch screen 100 can work normally. The components do not affect the setting process of the touch screen electrode signals of the present invention.

The structure of the touch screen 100 is first described in detail below:

The substrate 102 is composed of a transparent material, which may be polyethylene, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, glass, quartz. Or diamonds, etc.

The conductive film 104 is a conductive anisotropic film. Specifically, the conductivity of the conductive film 104 in the low impedance direction D is much larger than the conductivity in other directions, and the conductivity in the high impedance direction H is much smaller than the conductivity in other directions, and the low impedance direction D and the high impedance direction H vertical. In this embodiment, the conductive film 104 is composed of at least one layer of carbon nanotube film, which is directly obtained by pulling an array of carbon nanotubes. Most of the carbon nanotubes in the carbon nanotube film extend end to end in a preferred orientation in the same direction and are a self-supporting structure, and the self-supporting carbon nanotube film does not require a large area of carrier support. As long as the supporting force is provided on both sides, it can be suspended as a whole to maintain its own membranous state. The self-supporting is mainly achieved by the presence of a continuous carbon nanotube in the carbon nanotube film which is continuously arranged end to end by van der Waals force. Since the carbon nanotube has good electrical conductivity along its axial direction, and most of the carbon nanotubes in the above-mentioned carbon nanotube film extend in the same direction, the carbon nanotube film has an impedance anisotropy as a whole. The direction in which the carbon nanotube extends is a low impedance direction D, and the direction perpendicular to the carbon nanotube extends in a high impedance direction H. In addition, each of the carbon nanotubes in the majority of the carbon nanotube membranes extending in the same direction and the carbon nanotubes adjacent in the extending direction are connected end to end by van der Waals force. And a plurality of randomly arranged carbon nanotubes are also present in the carbon nanotube film, and the randomly arranged carbon nanotubes are in contact with adjacent other carbon nanotubes, so that the carbon nanotube film is The high-impedance direction H still has conductivity, but the resistance of the carbon nanotube film in the high-impedance direction H is larger and the conductivity is lower than in other directions. Further, the conductive film 104 is not limited to the carbon nanotube film, and may be other materials having impedance anisotropy, such as a plurality of strip-shaped indium tin oxide which are arranged in parallel with each other and parallel to the low-impedance direction D.

The plurality of first electrodes 106 are each formed of a conductive material, and the conductive material is optional The choice is metal, conductive polymer, conductive paste, conductive paste, metallic carbon nanotube or indium tin oxide. The shape and structure of the first electrode 106 are not limited and may be selected from a layer shape, a strip shape, a block shape, a rod shape or the like. In this embodiment, the first electrodes 106 are strip-shaped printed silver electrodes. The spacing between the adjacent two first electrodes 106 should be moderate, so that the position of the touch point is detected more accurately, and the spacing is preferably 3 mm to 5 mm. The length direction of each of the first electrodes 106 may be parallel to the high-impedance direction H of the conductive film 104, and the length is preferably 1 mm to 5 mm. The number of the first electrodes 106 is not limited and is determined according to the size of the area of the conductive film. In this embodiment, the number of the first electrodes 106 is eight, each of the first electrodes 106 has a length of 1 mm, and the distance between the adjacent two first electrodes 106 is 3 mm.

In the embodiment of the present invention, the optimal driving signal value is set to the first electrode 106 of the touch screen 100 by the above method. The specific process is: the IC 120 provides a current signal whose current value changes from small to large to sequentially drive each electrode of the first electrode 106. Please refer to FIG. 7 , which is a graph of driving signal values and initial capacitance values of eight first electrodes M1 , M2 , M3 , M4 , M5 , M6 , M7 , and M8 ( ie, initial capacitance value sets). The values of the ordinate are all digital signal values. Since the first electrode M8 is farthest from the IC 120 on the conductive path, the initial capacitance value of the electrode is the largest, and the first electrode M1 is closest to the IC 120 on the conductive path, and the initial capacitance value of the electrode is the smallest. Please also refer to Table 1, which is the whole process of the IC 120 searching for the optimal driving signal value for the electrode M1. First set the base capacitance value to 5800, set the natural number set to 0~2 ⁸ -1, that is, 0~255, and set the number of cycles to 8 times; the value in the natural number set is sequentially from small to large provided by the IC. The driving current signal value corresponds to. First, the center value 127 of the natural number set is selected, and the initial capacitance value corresponding to the driving signal value corresponding to the center value is 3122, and the initial capacitance value is smaller than the basic capacitance value, so the next time The selected value range is 0~127, and the center value 63 of the range is continuously selected, and the initial capacitance value corresponding to the center value is compared with the basic capacitance value. After repeating 8 times, the optimal driving signal of the electrode M1 is repeated. The value is the value of the drive current corresponding to the value 64.

Compared with the prior art, the present invention sets the optimal driving signal value of each electrode by adjusting the initial capacitance value of each electrode of the capacitive touch screen to the same value. That is, each electrode corresponds to a different optimal driving signal value. Generally, the electrode at the far end of the IC conductive path is driven by a larger driving signal, and the electrode at the proximal end of the IC conductive path is driven by a smaller driving signal. Therefore, after the touch, the capacitance of each electrode starts to change from the value of the basic capacitance, thereby ensuring that the changed capacitance value is still within the range set by the IC, and the variation of the capacitance value in the range is large, so that the touch can be detected more accurately. point.

In addition, referring to FIG. 8 , a second embodiment of the present invention provides a driving side of a touch screen. The method includes: S31, respectively providing a driving voltage to the driving electrodes of the touch screen, the driving voltage of each electrode is selected according to the method of the first embodiment of the present invention; and S32, touching the touch screen with a touch conductor, so that The capacitance of the touch position changes; S33, measuring the sensing electrode of the touch screen, reading the sensing signal output by the sensing electrode, and S34, analyzing the sensing signal to determine the touch point position.

Using the best driving signal value to drive the electrodes corresponding to the optimal driving signal of the touch screen, and reading the sensing signals at the electrodes, when the touch screen has no touch event, the capacitances read at all the electrodes are The same level (base capacitance value); when a touch event occurs, the capacitance at all the electrodes changes based on the value of the base capacitance, and the capacitance value of the electrode near the touch point changes relatively large, and other places The change in capacitance of the electrode is relatively small, which facilitates accurate detection of the position of the touch point.

In the above step S31, the touch screen of the present invention is suitable for a capacitive touch screen, and the capacitive touch screen can be a conventional surface acoustic wave capacitive touch screen or a projected capacitive touch screen. It can be understood that for the capacitive touch screen in which the driving electrode and the sensing electrode are separated, the optimal driving signal value can be provided only for its corresponding driving electrode. The embodiment of the present invention is driven based on the touch screen 100. Therefore, the electrodes of the touch screen 100 are both a driving electrode and a sensing electrode, that is, corresponding to the first electrode 106 and the second electrode 108. The partial or all of the first electrode 106 and the second electrode 108 of the touch screen 100 can be provided with the best driving signal value or the pulse signal of the optimal driving signal value. The embodiment of the present invention provides all the features of the touch screen 100. An electrode 106 and a second electrode 108 provide a pulse signal for their optimum drive signal value.

In the above step S32, the capacitance at the sensing electrode changes due to the change in capacitance of the position where the touch conductor touches the capacitive touch screen, so that each sensing electrode is subsequently used according to the subsequent The sensing signal read in can calculate the position of the touch point.

In the above step S33, the sensing electrodes are the first electrode 106 and the second electrode 108 in the embodiment of the present invention. The sensing signal can be current, voltage, capacitance or a change value of the parameters. In the embodiment of the invention, the sensing signal is a change value curve of the capacitance read by the first electrode 106 and the second electrode 108 before and after the touch.

In the above step S34, the position of the touched point can be obtained by changing the read sensing signal before and after the touch. This analysis method differs for touch screens of different structures and principles. The embodiment of the present invention provides a method for determining the position coordinates of the touch point based on the touch screen 100 described above. The method further includes the following steps: T1, determining a position coordinate of the touch point in the high impedance direction H by the capacitance change value curve of the first electrode 106 or the second electrode 108, and T2, combining the first electrode 106 and The capacitance change value curve of the second electrode 108 determines the position coordinates of the touch point in the low impedance direction D.

Referring to FIG. 5 and FIG. 9 together, FIG. 9 is a schematic diagram of a capacitance value change curve read by each of the first electrode 106 and the second electrode 108 according to an embodiment of the present invention. For convenience of description, the parameters and numbers in the figure are first described: I is the touch point, the touch point is close to the first electrode 106, and the coordinates of the touch point are (x, y). The plurality of second electrodes 108 are sequentially numbered N1, N2, N3, N4, N5, N6, N7, N8. The coordinates of the plurality of first electrodes 106 in the high impedance direction H are sequentially X ₁ , X ₂ , X ₃ , X ₄ , X ₅ , X ₆ , X ₇ , X ₈ , and due to the plurality of second electrodes 108 and The plurality of first electrodes 106 are opposite one another, so that the coordinates of the second electrode 108 and the first electrode 106 in the high impedance direction H are the same, that is, the coordinates of the plurality of second electrodes 108 in the high impedance direction H are also It is X ₁ , X ₂ , X ₃ , X ₄ , X ₅ , X ₆ , X ₇ , X ₈ . When the respective first electrodes 106 or the respective second electrodes 108 are described below, they will be replaced with their respective numbers. Further, ΔC _1i is a capacitance change value read at the Mi electrode of the first electrode 106, n=1, 2...8; correspondingly, ΔC _2i is read at the Ni electrode of the second electrode 108 Take the capacitance change value.

(1) determining the position coordinate of the touch point I in the high impedance direction H

The position coordinate of the high-impedance direction H of the touch point can be obtained by a capacitance value change curve of the first electrode 106 or the second electrode 108. In the embodiment of the present invention, the capacitance value change curve of the first electrode 106 is taken as an example. As can be seen from FIG. 7, in the capacitance value change curve of the first electrode 106, the M3 opposite to the touch point I is read out. The capacitance change value ΔC _{13 is the} largest, at the peak position of the capacitance value change curve of the entire first electrode 106. The two values ΔC ₁₂ and ΔC ₁₄ read by MZ and M4 adjacent to M3 are similar and much smaller than the value ΔC ₁₃ read by M3, and the other distance from the touch point I is further. The smaller the value of ΔC _1i read by the first electrode 106 is mainly because the touch point I is facing M3. Therefore, according to the waveform, it can be directly determined that the coordinate of the touch point I in the high impedance direction H is x=X ₃ . In addition, the coordinate of the touch point I in the high-impedance direction H can also be calculated by using the coordinates of the adjacent electrode and the capacitance change value of the ΔC _{13 having a} large change, as the formula can be: . It can be understood that other formulas can also be used to calculate the position coordinates of the touch point I in the high impedance direction H.

(2) determining the coordinates of the touch point I in the low impedance direction D

Since the conductive film 104 of the touch screen 100 is a conductive anisotropic film, the capacitance of the electrode near the touch point I changes greatly. That is, in the low impedance direction D, the closer the touch point is to the electrode, the larger the value of the capacitance change read from the electrode, the first side 111 and the second side 112 of the touch point I in the low impedance direction D. The vertical distance is substantially proportional to the ratio of the capacitance change value of the first electrode 106 to the capacitance change value of the second electrode 108. As can be seen from the figure, the capacitance change value of each electrode in the capacitance value change curve of the second electrode 108 is greater than the capacitance change value of the corresponding electrode in the capacitance value change curve of the first electrode 106. In the figure, ΔC _{23 is} at the peak position of the capacitance value change curve of the second electrode 108, and the capacitance change value and the capacitance change values ΔC ₂₂ and ΔC ₂₄ read at the electrodes N2 and N4 adjacent to the value can be utilized. And a distance relationship of the touch point I in the low impedance direction of the touch screen 100 to obtain a position coordinate in the low impedance direction D of the touch point. Such as: calculation The ratio of the touch point to the first side 111 and the second side 112 of the touch screen 100 can be calculated by the ratio, so that the position of the touch point I in the low impedance direction D can be located. coordinate.

In summary, the present invention has indeed met the requirements of the invention patent, and has filed a patent application according to law. However, the above description is only a preferred embodiment of the present invention, and it is not possible to limit the scope of the patent application of the present invention. Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

100‧‧‧ touch screen

120‧‧‧IC

122‧‧‧Wire

102‧‧‧Substrate

104‧‧‧Electrical film

106‧‧‧First electrode

108‧‧‧second electrode

111‧‧‧First side

112‧‧‧Second side

FIG. 1 is a flowchart of a method for setting a touch screen electrode driving signal according to an embodiment of the present invention.

FIG. 2 is a flowchart of a method for setting an optimal driving signal for each electrode of a touch screen according to an embodiment of the present invention.

FIG. 3 is a flowchart of a method for setting an optimal driving signal for each electrode of a touch screen according to an embodiment of the present invention.

FIG. 4 is a schematic diagram showing changes in the selection range in the method for setting the optimum driving signal value of each electrode of the touch screen according to the embodiment of the present invention.

FIG. 5 is a schematic top view of a touch screen in a method for setting a touch screen electrode driving signal according to an embodiment of the present disclosure;

FIG. 6 is a schematic side view of a touch screen in a method for setting a touch screen electrode driving signal according to an embodiment of the present invention.

FIG. 7 is a graph showing an initial capacitance value of a first electrode of a touch screen as a function of a driving signal value in a method for setting a driving voltage of a touch screen electrode according to an embodiment of the present invention.

FIG. 8 is a flowchart of a method for driving a touch screen according to an embodiment of the present invention.

FIG. 9 is a schematic diagram of a capacitance change value of an electrode for detecting a touch point I by a touch screen in a touch screen driving method according to an embodiment of the present invention.

Claims (10)

A method for setting a touch screen electrode driving signal, the method comprising the steps of: providing a changed driving signal to each electrode of the touch screen; and reading each electrode under the changed driving signal when the touch screen is not touched a set of initial capacitance values, and setting a base capacitance value, by comparing with the basic capacitance value, selecting an initial capacitance value closest to the basic capacitance value from the initial capacitance value set of each electrode, and driving the changed driving signal The driving signal value corresponding to the selected initial capacitance value is set as the optimal driving signal value of the electrode. The method for setting a touch screen electrode driving signal according to the first aspect of the invention, further comprising the step of reading the initial capacitance value set of each of the electrodes under the changed driving signal, and taking the average value . The method for setting a touch screen electrode driving signal according to claim 1, wherein an optimum driving signal value of each of the electrodes is determined by: setting a natural number set and the basic capacitance value. a tolerance range, wherein the value of the natural number set is sequentially corresponding to the driving signal value that changes from small to large, and the capacitance value corresponding to the driving signal value is an initial capacitance value; and the selection range is confirmed in the natural number set And arbitrarily selecting a value within the selected range, and reading an initial capacitance value corresponding to the value; comparing the initial capacitance value corresponding to the value with the basic capacitance value, and determining whether the initial capacitance value is at the basic capacitance Within the tolerance range of the value; when the initial capacitance value is within the tolerance of the base capacitance value, setting the driving signal value corresponding to the selected value as the optimal driving signal of the electrode a value; when the initial capacitance value is not within the tolerance range of the base capacitance value, returning to re-determine the selection range in the natural number set, and continuing to select the value in the natural number set within the range. The method for setting a touch screen electrode driving signal according to claim 3, wherein the redetermining the selection range further comprises: when the initial capacitance value is less than the basic capacitance value, selecting a range of the next time value It is: from the lower limit value of the selected range to the value selected this time; when the initial capacitance value is greater than the basic capacitance value, the selection range of the next time value is: from the value selected this time to The upper limit of the range is selected in this time. The method for setting a touch screen electrode driving signal according to claim 3, wherein the optimal driving signal value of each of the electrodes is set by setting a natural number set to 0~(2 ^t -1) And t is a natural number, and the value of the natural number set corresponds to the driving signal value that is changed from small to large for the touch screen electrode, and the capacitance value corresponding to the driving signal value is an initial capacitance value; in the natural number set Confirming the selected range, selecting a central value of the natural number set in the selected range, and reading an initial capacitance value corresponding to the central value; comparing the initial capacitance value with the basic capacitance value, determining the initial capacitance value and the basis Whether the capacitance value is equal; when the initial capacitance value is equal to the basic capacitance value, the driving signal value corresponding to the center value is set as the optimal driving signal value of the electrode; when the initial capacitance value is not equal to the basic capacitance value When it returns, the selection range is reconfirmed in the natural number set, and the center value of the natural number set is selected within the selection range. The method for setting a touch screen electrode driving signal according to claim 5, wherein the reconfirming the selection range further comprises: when the initial capacitance value is less than the basic capacitance value, the next selection of the central value It is: from the lower limit of the current selection range to the central value of the current selection; when the initial capacitance value is greater than the basic capacitance value, the next central value is selected from the center value selected this time to this time. Select the upper limit of the range. The method for setting a touch screen electrode driving signal according to claim 5, wherein the number of times the center value is reselected when the initial capacitance value is not equal to the basic capacitance value is further set. The method for setting a touch screen electrode driving signal according to claim 5, further comprising setting a tolerance range of the basic capacitance value, when the initial capacitance value is not equal to the basic capacitance value but at the basic capacitance In the tolerance range of the value, the corresponding driving signal value is also set as the step of the optimal driving signal value of the electrode. The method for setting a touch screen electrode driving signal according to any one of claims 1 to 8, wherein the touch screen comprises one or more transparent conductive layers, and the transparent conductive layer material is a carbon nanotube or Indium tin oxide. A driving method of a touch screen, the method comprising the steps of: respectively providing a driving voltage to a driving electrode of the touch screen, wherein a driving voltage of each electrode is selected according to the method described in claim 1 of the patent application; the touch conductor is used; Touching the touch screen to change the capacitance of the touch position; measuring the sensing electrodes of the touch screen, reading the sensing signals output by the sensing electrodes, and analyzing the sensing signals to determine the touch point position.