TWI853385B - Touch detection method of touch panel and touch display - Google Patents

Abstract

A touch detection method for a touch panel is provided. The touch detection method includes: executing the following steps with a processor: alternately driving the touch panel in a plurality of polarity inversion modes; for each touch unit of the touch panel, the signal value of the touch unit is detected within a predetermined time interval, the signal value is compared with a signal threshold, and the retained signal value of each touch unit is used as a touch result. The predetermined time interval includes a plurality of time counting units; if the signal value remains higher than a signal threshold for a predetermined continuous count, the signal value is retained, otherwise the signal value is filtered out.

Description

Touch detection method for touch panel and touch display

The present invention relates to the technology of touch panel, and more particularly to a method for detecting and filtering noise of the touch panel.

Capacitive touch panels are now widely used in mobile devices and wearable devices. The accuracy of touch is affected by panel noise, which has always been a problem that needs to be solved urgently. Currently, touch panels mainly deal with panel noise by frequency hopping or using synchronization signals to receive touch signals during the blanking period of the panel to avoid noise interference. However, the frequency hopping method uses a fixed frequency and cannot be adjusted according to the influence of external environmental factors. In addition, the synchronization signal method is limited by the time limit of the blanking period of the panel, which affects the speed of receiving and processing touch signals. Therefore, even though the prior art has proposed some solutions to process noise, under bad environmental conditions, the noise may still be misjudged as a touch operation.

In summary, there is a need for a more accurate solution that is less affected by the external environment and the panel's own characteristics to detect and filter the noise of the touch panel so as to more accurately identify the touch operation.

In response to the above requirements, this case proposes a method for panel noise detection and filtering, which makes the judgment of touch events of related products more stable.

An embodiment of the present invention provides a touch detection method for a touch panel, comprising driving the touch panel alternately in a plurality of polarity reversal modes; for each touch unit of the touch panel, detecting the signal value of the touch unit within a predetermined time interval, and comparing the signal value with a signal threshold value, and taking the signal value retained by each touch unit as a touch result. The predetermined time interval includes a plurality of time counting units; if the signal value maintains a state higher than the signal threshold value for a predetermined continuous count, the signal value is retained, otherwise the signal value is filtered out.

Another embodiment of the present invention provides a touch display, including a touch panel and a processor, wherein the processor provides a plurality of polarity inversion modes to alternately drive the touch panel, and the touch panel has at least one touch unit, the processor detects a signal value of the at least one touch unit within a predetermined time interval, and compares the signal value with a signal threshold value, wherein the predetermined time interval includes a plurality of time counting units; if the signal value is higher than a signal threshold value for a predetermined continuous count, the signal value is retained; if the signal value is not higher than the signal threshold value for the predetermined continuous count, the signal value is filtered.

In summary, the present invention effectively determines whether the signal value sensed by the touch panel is from a real touch operation or the noise generated by the polarity reversal by interlacing different polarity reversal modes, thereby retaining the signal value generated by the actual touch and filtering out the noise. In this way, the accuracy of the touch panel in identifying the touch operation can be greatly improved, and the method of the present invention is not affected by the external environment and the characteristics of the panel itself, so it can effectively solve the problems faced by the previous technology.

The present invention is particularly described with the following examples, which are used for illustration only, because for those skilled in the art, various changes and modifications can be made without departing from the spirit and scope of the present disclosure, so the scope of protection of the present disclosure shall be determined by the scope of the attached patent application. Throughout the specification and the patent application, unless the content clearly specifies otherwise, the meaning of "one" and "the" includes such a description including "one or at least one" element or component. In addition, as used in the present invention, unless it is obvious from the specific context that the plurality is excluded, the singular article also includes the description of plural elements or components. Moreover, when applied in this description and the entire patent application below, unless the content clearly specifies otherwise, the meaning of "in which" may include "in which" and "on which". The terms used throughout the specification and the patent application generally have the ordinary meaning of each term used in the field, in the content disclosed herein and in the specific content, unless otherwise noted. Certain terms used to describe the present invention will be discussed below or elsewhere in this specification to provide practitioners with additional guidance on the description of the present invention. Examples anywhere throughout the specification, including the use of examples of any term discussed herein, are used for illustrative purposes only and certainly do not limit the scope and meaning of the present invention or any exemplified term. Similarly, the present invention is not limited to the various embodiments presented in this specification.

As used herein, the terms "substantially", "around", "about" or "approximately" shall generally mean within 20%, preferably within 10%, of a given value or range. In addition, the quantities provided herein may be approximate, so it is meant that unless otherwise stated, they may be expressed using the terms "about", "approximately" or "approximately". When a quantity, concentration or other numerical value or parameter has a specified range, a preferred range or lists upper and lower ideal values, it should be deemed to specifically disclose all ranges consisting of any upper and lower limit pairs or ideal values, regardless of whether the same ranges are disclosed separately. For example, if a length is disclosed as X cm to Y cm, it should be deemed to disclose a length of H cm and H can be any real number between X and Y.

In addition, if the term "electrically coupled" or "electrically connected" is used, it includes any direct and indirect electrical connection means. For example, if the text describes that a first device is electrically coupled to a second device, it means that the first device can be directly connected to the second device, or indirectly connected to the second device through other devices or connection means. In addition, if the transmission and provision of electrical signals are described, those familiar with this technology should understand that the transmission process of electrical signals may be accompanied by attenuation or other non-ideal changes, but if the source and receiving end of the transmission or provision of electrical signals are not specifically stated, they should be regarded as the same signal in essence. For example, if an electrical signal S is transmitted (or provided) from terminal A of an electronic circuit to terminal B of the electronic circuit, a voltage drop may be generated through the source and drain terminals of a transistor switch and/or possible stray capacitance. However, if the purpose of this design is not to intentionally use the attenuation or other non-ideal changes generated during transmission (or provision) to achieve certain specific technical effects, the electrical signal S at terminals A and B of the electronic circuit should be considered to be essentially the same signal.

It is understood that the terms "comprising", "including", "having", "containing", "involving", etc. used herein are open-ended, meaning including but not limited to. In addition, any embodiment or patent application scope of the present invention does not need to achieve all the objects, advantages or features disclosed in the present invention. In addition, the abstract part and the title are only used to assist the search for patent documents, and are not used to limit the scope of the patent application of the present invention.

In view of the fact that the panel noise source is mostly caused by the coupling between the polarity conversion of the pixel arrangement light/dark and the reference voltage (VCOM), the present invention uses the signal (noise) difference represented by a variety of different polarity conversions to determine the panel noise and then filter it.

Please refer to FIG. 1, which is a schematic diagram of a touch display 100 of the present invention. As shown in FIG. 1, the touch display 100 includes a touch panel 110 and a processor 120. The processor 120 controls a plurality of polarity inversion modes to alternately drive the touch panel, more specifically, uses different polarity inversion modes to invert the liquid crystal. Then, for each touch unit of the touch panel 110, the processor 120 detects the signal value of each touch unit within a predetermined time interval, wherein each touch unit can be a single pixel or a group of 3×3 pixels. The present invention does not particularly limit the size of the touch unit. The detected signal value is further compared with the signal threshold value. The signal threshold value can be adjusted according to the actual design requirements. The main function is to compare the signal value to exclude the signal component caused by the environmental noise (such as white noise). Among them, the predetermined time interval includes a plurality of time counting units; if the signal value remains higher than the signal threshold value for a predetermined continuous count, the signal value is retained; if the signal value remains higher than the signal threshold value but does not reach the predetermined continuous count, the signal value (i.e., the noise component) is filtered out. As mentioned above, the processor 120 is further used to filter out noise, and after filtering out the noise, the processor 120 will use the last retained signal value of each touch unit as the touch result.

For example, FIG. 2A and FIG. 2B respectively illustrate the pixel detection signal values of the touch panel in different frames. TX0-TX8 represent row pixels, RX0-RX8 represent column pixels, and the number marked on each pixel in the figure represents the signal value detected by the processor 120. Referring to FIG. 2A , when the image is in the first frame (indicated by “Frame 1”), the polarity inversion type adopted is dot inversion (indicated by “Dot”, and further examples can be seen in FIG. 3B ), and the touch panel 110 detects signal values (positive values are still presented after deducting the signal threshold value) at a number of pixels in the lower left corner (a 3×3 pixel group centered on the pixel with coordinates (TX7, RX1)) and a number of pixels in the upper left corner (i.e., pixels with coordinates (TX1, RX0), (TX1, RX2), (TX1, RX4), (TX2, RX2), and (TX2, RX3)). Next, referring to FIG. 2B , when the image is in the second frame (represented by Frame 2), the polarity inversion type adopted is “2V+1” inversion (for further example, see FIG. 3B ) represented by “2V+1”), and the touch panel 110 detects signal values at a number of pixels in the lower left corner (a 3×3 pixel group centered on the pixel with coordinates (TX7, RX1)) and a number of pixels in the lower right corner (i.e., pixels with coordinates (TX6, RX5), (TX6, RX6), (TX6, RX7), (TX7, RX7), and (TX7, RX8)). By comparing the first frame shown in FIG. 2A with the second frame shown in FIG. 2B , it can be seen that the signal values detected by some pixels with signal values in the lower left corner remain unchanged, so it can be known that they are signal values contributed by real touch; on the contrary, some pixels with signal values in the upper left corner are only detected as having signal values in the first frame, and no signal values are detected in the second frame (zero or negative value after deducting the signal threshold value), that is, the signal values of these pixels in the upper left corner cannot be maintained for two frames, and it can be determined that these pixels in the upper left corner are noise values, and then the signal values of these pixels in the upper left corner are filtered by the processor 120. The above example uses two frames as the predetermined continuous count (i.e., the signal value must continue for a certain number of frames to be considered as being generated by actual touch rather than noise), but this judgment condition may be different in other embodiments of the present invention. It should be noted that the term "filtering" in this article can be implemented as not including the "filtered pixel position" in the calculation when counting the touch position; in addition, an inverted signal can be generated to offset the signal value of the "filtered pixel position". The present invention mainly focuses on determining the pixel position where noise appears (equivalent to the position of "false touch"), and does not limit the method of filtering noise. Please note that the detected signal values or noise values mentioned above are all components that are still positive after being compared with the signal threshold value, while components below the signal threshold value are regarded as environmental noise (such as white noise) and are filtered out.

For example, if the operating frequency of the touch panel 110 is 60 Hz, the predetermined time interval may include 60 time count units (i.e., 60 frames). Thus, the maximum predetermined continuous count is 59, and the predetermined continuous count may be an integer between 2 and 59. Generally speaking, the predetermined continuous count is set to 2 to effectively determine whether the measured signal is actually generated by a touch. However, sometimes different polarity inversion modes may also cause noise to appear at the same pixel position in the same two frames. In this case, the predetermined continuous count value may be increased to avoid misjudging the noise as a touch signal. However, the predetermined continuous count may not exceed the maximum predetermined continuous count.

Refer to FIG. 3A, which is a schematic diagram of using the two polarity inversion modes in FIG. 2A and FIG. 2B interchangeably and counting, wherein the number annotated on each pixel represents the current count value (i.e., the accumulated number of times) of the pixel having a signal component (the above signal value minus the signal threshold value is still greater than or equal to 0) in the frame so far. As shown in FIG. 3A, after counting two frames, only the pixels with coordinates (TX6, RX5), (TX6, RX6), (TX6, RX7), (TX7, RX7), (TX7, RX8) have a count value of 2, so the signal values on these pixels will be retained, and the signal values on other pixels with a count value of 1 will be filtered out.

FIG3B is a schematic diagram of various polarity inversion modes, which lists several common (but not all types) polarity inversion modes, namely frame inversion, line inversion, column inversion, dot inversion, and (2V+1) inversion. The present invention will execute at least two of the various polarity inversion modes when determining noise. For example, the embodiment of FIG3A adopts two modes, dot inversion and (2V+1) inversion, but in other embodiments, three or more polarity inversion modes may be used to filter noise.

Refer to FIG. 4, which is a schematic diagram of the touch detection method for a touch panel of the present invention, which can be understood in conjunction with FIG. 2A, FIG. 2B, FIG. 3A and FIG. 3B. Step S402 selects at least two polarity inversion modes, such as the polarity inversion modes listed in FIG. 3B, and drives the liquid crystal alternately, wherein the alternating modes can be as shown in Table 1, but the present invention is not limited thereto. Table 1 Mode 1: Frequency = 60Hz, N = 2, proportional insertion Mode 2: Frequency = 60Hz, N = 3, non-proportional insertion Frame 1 Point Reverse Frame 1 Point Reverse Frame 2 (2V+1) Reverse Frame 2 Point Reverse Frame 3 Point Reverse Frame 3 (2V+1) Reverse Frame 4 (2V+1) Reverse Frame 4 Point Reverse Frame 5 Point Reverse Frame 5 Point Reverse Frame 6 (2V+1) Reverse Frame 6 (2V+1) Reverse … … … … Frame 59 Point Reverse Frame 59 Point Reverse Frame 60 (2V+1) Reverse Frame 60 (2V+1) Reverse

In Table 1, the operating frequency of the touch panel is 60Hz, and the predetermined time interval may include 60 time counting units (i.e., 60 frames, represented by "Frame" in the table), wherein Mode 1 is an example of an equal-proportional insertion mode, and Mode 2 is an example of a non-equal-proportional insertion mode. Mode 1 and Mode 2 both include two inversion modes, namely, dot inversion and (2V+1). N=2 means that a (2V+1) inversion mode is inserted into one frame every two frames, and N=3 means that a (2V+1) inversion mode is inserted into one frame every three frames. In steps S404 to S414, see FIG. 3A. For a touch unit, the detected signal value will be retained only if it remains greater than the signal threshold value for a predetermined continuous count (e.g., the count reaches any integer between 2 and 59), otherwise it will be filtered. In step 416, the signal values finally retained by all touch units are used as the final touch result, and the number of touch units can be single or multiple.

Further, in mode 1, from the first frame (Frame 1) to the last frame (Frame 60), the touch panel is driven in the dot inversion mode in the odd frames, and the touch panel is driven in the (2V+1) inversion mode in the even frames. In mode 2, from the first frame to the last frame, the (3N-1)th frame and the (3N-2)th frame are driven in the dot inversion mode, and the 3Nth time counting unit is driven in the (2V+1) inversion mode, where N is a positive integer. Please note that the dot inversion mode and (2V+1) inversion mode in Mode 1 and Mode 2 disclosed in Table 1 both follow an ordered schedule to alternately drive the touch panel, but in other embodiments of the present invention, the touch panel may also be alternately driven according to a random schedule, that is, the (2V+1) inversion mode does not appear periodically. In addition, the dot inversion mode and (2V+1) inversion mode in Mode 1 and Mode 2 disclosed in Table 1 may be replaced by any of the diode inversion modes in FIG. 3B.

Please refer to FIG5, which is a flow chart of a touch detection method for a touch panel according to an embodiment of the present invention. Please note that if substantially the same result can be obtained, these steps do not necessarily have to be executed in the execution order shown in FIG5. The touch detection method shown in FIG. 5 can be adopted by the touch display 100 shown in FIG. 1 and can be simply summarized into the following steps: Step S502:    Alternately drive the touch panel in a plurality of polarity reversal modes; Step S504:    Detect the signal value of each touch unit of the touch panel within a predetermined time interval; Step S506:    Compare the signal value of each touch unit with the signal threshold value. If the signal value maintains a state higher than the signal threshold value for a predetermined continuous count, retain the signal value; if not (the signal value does not maintain a state higher than the signal threshold value for a predetermined continuous count), filter out the signal value; Step S508:    The signal value retained by each touch unit is used as the touch result.

In summary, the present invention effectively determines whether the signal value sensed by the touch panel is from a real touch operation or the noise generated by the polarity reversal by interlacing different polarity reversal modes, thereby retaining the signal value generated by the actual touch and filtering out the noise. In this way, the accuracy of the touch panel in identifying the touch operation can be greatly improved, and the method of the present invention is not affected by the external environment and the characteristics of the panel itself, so it can effectively solve the problems faced by the previous technology.

Since a skilled person can easily understand the details of each step in FIG. 5 after reading the above paragraphs, further description will be omitted here for the sake of brevity.

Although the present invention has been disclosed as above by way of embodiments, they are not intended to limit the present invention. A person having ordinary knowledge in the technical field to which the present invention belongs may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined in the attached patent application.

100: Touch display 110: Touch panel 120: Processor S402-S416, S502-S508: Steps

FIG. 1 is a schematic diagram of a touch display of the present invention. FIG. 2A and FIG. 2B are schematic diagrams of pixel detection signal values of a touch panel in different frames, respectively. FIG. 3A is a schematic diagram of using the two polarity inversion modes in FIG. 2 interchangeably and counting. FIG. 3B is a schematic diagram of multiple polarity inversion modes. FIG. 4 is a schematic diagram of a touch detection method for a touch panel of the present invention. FIG. 5 is a flow chart of a touch detection method for a touch panel according to an embodiment of the present invention.

S502-S508: Steps

Claims (9)

A touch detection method for a touch panel, comprising: driving the touch panel alternately in a plurality of polarity reversal modes; performing the following steps for each touch unit of the touch panel: detecting a signal value of the touch unit within a predetermined time interval, the predetermined time interval comprising a plurality of time counting units; and comparing the signal value with a signal threshold value, wherein if the signal value maintains a state higher than the signal threshold value for a predetermined continuous count, the signal value is retained, otherwise the signal value is filtered out; and taking the signal value retained by each touch unit as a touch result; wherein the plurality of polarity reversal modes include driving the touch panel alternately in a non-proportional manner. As described in claim 1, the touch detection method, wherein the operating frequency of the touch panel is 60 Hz, the predetermined time interval includes 60 time counting units, and the predetermined continuous count is an integer between 2 and 59. In the touch detection method described in claim 1, the plurality of polarity inversion modes include at least two of frame inversion, line inversion, column inversion, dot inversion, and (2V+1) inversion. A touch detection method as described in claim 1, wherein the plurality of polarity reversal modes include driving the touch panel alternately in a proportional manner. The touch detection method as described in claim 4, wherein the step of driving the touch panel alternately in a proportional manner comprises: driving the touch panel in a first polarity inversion mode for odd-numbered time counting units among the plurality of time counting units; and driving the touch panel in a second polarity inversion mode for even-numbered time counting units among the plurality of time counting units. The touch detection method as described in claim 1, wherein the step of alternately driving the touch panel in a non-proportional manner comprises: driving the touch panel in a first polarity inversion mode in the (3N-1)th and (3N-2)th time counting units among the plurality of time counting units, wherein N is a positive integer; and driving the touch panel in a second polarity inversion mode in the 3Nth time counting unit among the plurality of time counting units. A touch display includes a touch panel and a processor, wherein the processor provides a plurality of polarity inversion modes to alternately drive the touch panel, and the touch panel has at least one touch unit, the processor detects a signal value of the at least one touch unit within a predetermined time interval, and compares the signal value with a signal threshold value, wherein the predetermined time interval includes a plurality of time counting units; if the signal value is higher than a signal threshold value for a predetermined continuous count, the signal value is retained; if the signal value is not higher than the signal threshold value for the predetermined continuous count, the signal value is filtered; wherein the plurality of polarity inversion modes include alternately driving the touch panel in a non-proportional manner. A touch display as described in claim 7, wherein the at least one touch unit is a single pixel. A touch display as described in claim 7, wherein the at least one touch unit comprises a plurality of pixels.

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