Touch panel and method for processing signals of the touch panel

A touch panel includes a display module, a touch sensor and a signal processing unit. The display module includes a timing control circuit and a data driving circuit, wherein the timing control circuit outputs latch signals to the data driving circuit, and the display module generates surface noises. The touch sensor is disposed above the display module and outputs abnormal signals, wherein the abnormal signals include a sensing signal and the surface noises. The signal processing unit is electrically connected to the touch sensor and receives the abnormal signals, wherein the signal processing unit calculates a predetermined time by utilizing a rising edge or a falling edge of the latch signal, suspensively processes the sensing signal during the predetermined time, and then continuously processes the sensing signals beyond the predetermined times so as to keep away from each period of the surface noises.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Taiwan Patent Application No. 101103528, filed on Feb. 3, 2012, which is hereby incorporated by reference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates to a method for processing signals, and more particularly to a method for processing signals of a touch panel.

2. Related Art

Techniques of touch panels are advanced in recent years, such as resistive touch panels, capacitive touch panels, surface acoustic wave touch panels, and optical touch panels. The said techniques have been applied to communication products, computer devices and consumer electronic products for increasing functions of said applied products and convenient usage.

The capacitive touch panels can be operated by fingers without pressing the capacitive touch panels heavily, so the capacitive touch panels has no disadvantage of a stress caused by repeatedly touching the touch panel, and a damage caused by deformation. Advantages of the capacitive touch panels are that the capacitive touch panels are with simple structures, less elements and a high product yield rate, so the capacitive touch panels are adapted for mass production, whereby the cost of the capacitive touch panels can be reduced.

FIG. 1shows a cross sectional view of a conventional touch sensor100. The touch sensor100includes a glass substrate110, two optically clear adhesive (OCA) layers120, an indium tin oxide (ITO) layer130and a cover lens140. A gap of the touch sensor100between the glass substrate110and the ITO layer130is filled with one of the two OCA layers120for bonding the glass substrate110and the ITO layer130; the other gap of the touch sensor100between the ITO layer130and the cover lens140is filled with another OCA layer120for bonding the ITO layer130and the cover lens140.

FIG. 2is a cross sectional view of a conventional touch panel200. The conventional touch panel200includes the touch sensor100and a liquid crystal display module (LCM)250. The touch sensor100is located above the LCM250. An air gap260is formed between the glass substrate110and the LCM250.

FIG. 3is a schematic view showing signal processing of the conventional touch panel. The conventional touch panel includes the touch sensor100, an analog to digital (A/D) converter330, a microcontroller340, a transmission interface350and an operating system360. When the touch panel200is touched, a corresponding capacitance value is changed. Then, the touch sensor100outputs an analog signal to the A/D converter330. The A/D converter330converts the analog signal to a digital signal, and then outputs the digital signal to the microcontroller340. The microcontroller340processes the digital signal, and then outputs a control signal. Finally, the control signal is transmitted to an operating system360through the transmission interface350for determining touch locations of the touch panel200.

However, after a touch sensor is assembled on an LCD module, the touch sensor is interfered by noises generated from the LCD module so as to cause a misjudgment of touch locations. For example, when the LCD module is normally operated, different surface noises are generated by different pictures of the LCD module. For another example, when the picture of the LCD module is fast updated or is in a heavy loading, an unstable voltage (i.e. surface noise) is detected from a surface of the LCD module.FIG. 4is timing charts of the surface noises of the LCD module. When red, green and blue (RGB) pixels of the LCD module show a picture having bright lines and dark lines separated from one another, or the RGB pixels of the LCD module show a black picture (heavy loading), the surface noises can be generated.

Accordingly, a problem of the surface noises for the touch panel and a method for processing signal of the touch panel needs to be solved.

SUMMARY OF THE INVENTION

A purpose of the present invention is to solve a touch sensor interfered with surface noises from a display module of the touch panel.

This invention provides a touch panel including a display module, a touch sensor and a signal processing unit. The display module includes a timing control circuit and a data driving circuit, wherein the timing control circuit outputs latch signals to the data driving circuit, and the display module generates surface noises. The touch sensor is disposed above the display module and outputs abnormal signals, wherein the abnormal signals include a sensing signal and the surface noises. The signal processing unit is electrically connected to the touch sensor and receives the abnormal signals, wherein the signal processing unit calculates a predetermined time by utilising a rising edge or a falling edge of the latch signal, suspensively processes the sensing signal during the predetermined time, and then continuously processes the sensing signals beyond the predetermined times so as to keep away from each period of the surface noises.

This invention further provides a method for processing signals processing method of a touch panel, the method comprising the following steps of: in Step A, providing a display module and a touch sensor, wherein the display module comprises a timing control circuit outputting latch signals, the display module generates surface noises, the touch sensor is deposed above the display module and outputs abnormal signals which each comprise a sensing signal and the surface noises; in Step B, receiving the abnormal signals and calculating a predetermined time according to a rising edge or a falling edge of each duty period of the latch signals; and in Step C, suspensively processing the sensing signals during the predetermined time and then continuously processing the sensing signals beyond the predetermined times so as to keep away from each period of the surface noises.

The touch panel including the signal processing unit of this invention can solve a misjudgment problem that the touch sensor is interfered by surface noises from the display module.

In order to make the aforementioned and other objectives, features and advantages of the present invention comprehensible, embodiments are described in detail below with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 5is a schematic view of a touch panel400according to an embodiment of this invention, wherein the touch panel400includes a display module640, a touch sensor410and a signal processing unit430. The touch sensor410is deposed above the display module640(such as an LCD module), and is electrically connected to the signal processing unit430.

FIG. 6is a schematic view of the display module640according to the embodiment of this invention. The display module640includes a timing control circuit610, a scan driving circuit620and a data driving circuit630. The timing control circuit610outputs vertical synchronizing signals STV and enable signals OE to the scan driving circuit620. The scan driving circuit620outputs scanning signals SS(1)˜SS(m) to scan lines of the display module640. In coordination with timing of the scanning signals outputted from the scan driving circuit620, the timing control circuit610also outputs horizontal synchronizing signals STH, digital display data DD and latch signals TP to the data driving circuit630. The data driving circuit630outputs display signals AD(1)˜AD(n) to data lines of the display module640, so as to show images on the display module640.

FIG. 7is timing charts of horizontal synchronizing signals, latch signals and surface noises of the display module640. The surface noises of the display module640and the latch signals TP of the timing control circuit610are synchronized. On the other hand, the surface noises of the display module640and a horizontal synchronizing signal STH are not fully synchronized. The signal processing unit430includes a signal line542and a microcontroller540. The microcontroller540is electrically connected to the timing control circuit610by the signal line542for receiving the latch signals, shown inFIG. 5. The latch signals have a plurality of duty periods, and each duty period has a rising edge and a falling edge. The microcontroller540received the abnormal signals, and can calculate predetermined times by utilising the rising edge and the falling edge of each duty period of the latch signals. The microcontroller540suspensively processes the sensing signals during the predetermined times, and then the microcontroller540continuously processes the sensing signals beyond the predetermined times so as to keep away from each period of the surface noises. For example, predetermined times T are calculated by utilising the rising edge of each duty period of the latch signals. The sensing signal will be not processed during the predetermined times T. The predetermined time T is longer than a generating time of each period of the surface noises of the display module640. For example, the predetermined time T can be set to be longer than 3.52 μs.

With reference toFIG. 8, the signal processing unit432further includes an analog to digital (A/D) converter530, a transmission interface550and an operating system560. Initially, the touch sensor410should output only a sensing signal to the A/D converter530. Unfortunately, the touch sensor410outputs the abnormal signal including the sensing signal and the surface noises to the A/D converter530, because the touch sensor410is interfered by the surface noises from the display module640. The A/D converter530converts analog types of the abnormal signal to digital types of the abnormal signal, and outputs the digital type of the abnormal signal to the microcontroller540. After the microcontroller540receives the abnormal signal, the microcontroller540processes the abnormal signal except the generating time of each period of the surface noises. Then, the microcontroller unit540outputs control signals to the operating system560through the transmission interface550, so the operating system560calculates and then determines touch locations on the touch panel400. For example, when a touch panel is touched, a corresponding capacitance value is changed so as to cause the sensing signal being varied, and then touch locations are determined by the sensing signal. The signal processing unit430can be called as a touch IC.

FIG. 9is a flow chart showing a method for processing signals of the touch panel400according to an embodiment of the present invention.

In step S900, a display module640and a touch sensor410are provided, wherein the display module640includes a timing control circuit610, the timing control circuit610outputs latch signals TP; the display module640generates surface noises, the touch sensor410is deposed above the display module640, and the touch sensor410outputs abnormal signals which each includes sensing signal and the surface noises. The surface noises synchronize with the latch signals, and are unstable voltages detected from a surface of the display module640.

In step S902, analog types of the abnormal signals are converted to digital types of the abnormal signals.

In step S904, the abnormal signals are received and a predetermined time is calculated according to a rising edge or a falling edge of each duty period of the latch signals.

In step S906, the sensing signals are suspensively processed during the predetermined time, and then the sensing signals are continuously processed beyond the predetermined times so as to keep away from each period of the surface noises, wherein the predetermined time is longer than a generating time of each period of the surface noises.

In step S908, control signals are outputted.

In step S910, the control signals are operated so as to determine touch locations.

The touch panel including the signal processing unit of this invention can solve a misjudgment problem that the touch sensor is interfered by surface noises from the display module.