TWI798863B - Polarity conversion method of liquid crystal panel with variable refresh rate, liquid crystal display and information processing device - Google Patents

Abstract

A method for changing the polarity of a liquid crystal panel with a variable refresh rate, comprising: dividing the frequency of a vertical synchronization signal by a reference frequency to generate a ratio M/N, where M is greater than N, and M and N are mutually prime positive integers; And make a source driving circuit change the polarity of the driving voltage N times during the driving process of every M frames of pictures.

Description

Polarity conversion method of liquid crystal panel with variable refresh rate, liquid crystal display and information processing device

The invention relates to a driving method of a liquid crystal panel, in particular to a polarity conversion method of a driving voltage of a liquid crystal panel which can minimize power consumption.

The main working principle of the liquid crystal panel is to adjust the rotation angle of the liquid crystal molecules of the R, G, and B sub-pixels of each pixel through the corresponding driving voltage to change the backlight transmittance of each R, G, and B sub-pixel, and then through the color filter The filter function of the chip makes each pixel display the desired color. As far as a general liquid crystal panel is concerned, its liquid crystal molecules are sandwiched between upper and lower layers of glass to be driven by a vertical electric field. However, liquid crystal molecules have a characteristic that they cannot be driven at a certain fixed voltage all the time, otherwise, polarization will occur over time and the liquid crystal molecules will not be able to rotate with the change of the applied electric field, resulting in the failure of the liquid crystal panel to provide normal display functions. In addition, when the absolute value of the driving voltage is the same, the liquid crystal molecules will have the same light transmittance after rotation to present the same gray scale. exchange to avoid polarization of the liquid crystal molecules.

However, when the positive and negative polarities of the driving voltage are periodically switched, the driving circuit will periodically charge and discharge all the parasitic capacitances in the liquid crystal panel to generate power consumption. Please refer to FIG. 1 , which illustrates a common polarity exchange method of a liquid crystal panel. As shown in Figure 1, a liquid crystal panel displays images at a frame rate of 60Hz, that is, updating one frame every 16.6ms. Among them, F1~F4 represent 4 frames, and S1~S8 represent the output channels of the source driver chip. G1~G8 represent the output channels of the gate driver chips, and the LCD panel switches the positive and negative polarities of the driving voltage every frame.

In addition, in order to improve the display quality of the liquid crystal panel, a liquid crystal panel with a high refresh rate, such as a _240Hz refresh rate, has been proposed. However, the liquid crystal panel with a high refresh rate will increase the power consumption multiple times during the polarity exchange process of the driving voltage.

In order to solve the above problems, there is an urgent need in the art for a novel polarity switching method for liquid crystal panels.

The main purpose of the present invention is to disclose a method for changing the polarity of a liquid crystal panel with a variable refresh rate, which can adaptively determine a frame period by detecting the frequency of a vertical synchronization signal to change the polarity of a driving voltage of a liquid crystal panel , so as to minimize the power consumption of the liquid crystal panel during the polarity exchange of the driving voltage.

Another object of the present invention is to disclose a liquid crystal display, which can minimize the power consumption generated by polarity switching by using the above-mentioned polarity switching method when displaying images at a high refresh rate.

Another object of the present invention is to disclose an information processing device having the above-mentioned liquid crystal display to minimize the power consumption generated by the polarity switching by the above-mentioned polarity switching method when displaying images at a high refresh rate.

In order to achieve the aforementioned purpose, a polarity conversion method of a liquid crystal panel with a variable refresh rate is proposed, which includes:

Dividing the frequency of a vertical synchronization signal by a reference frequency to generate a ratio M/N, where M is greater than N, and M and N are relatively prime positive integers; and

A source driving circuit is made to change the polarity of the driving voltage N times during the driving process of every M frames of pictures.

Preferably, the period of the reference frequency is lower than the duration of vision.

In a possible embodiment, N=1 or greater than 1.

In a possible embodiment, the ratio can be obtained by means of software or hardware.

In order to achieve the aforementioned purpose, the present invention further proposes a liquid crystal display, which includes a liquid crystal panel, a control circuit, and a source driver circuit, wherein the control circuit is used to execute a polarity change procedure, and the polarity change procedure includes:

Dividing the frequency of a vertical synchronization signal by a reference frequency to generate a ratio M/N, where M is greater than N, and M and N are relatively prime positive integers; and

The source driving circuit is made to drive the liquid crystal panel according to a polarity switching mode, and the polarity switching mode is to change the polarity of the driving voltage N times during the driving process of every M frames of images.

Preferably, the period of the reference frequency is lower than the duration of vision.

In a possible embodiment, N=1 or greater than 1.

In a possible embodiment, the ratio can be obtained by means of software or hardware.

To achieve the aforementioned purpose, the present invention further proposes an information processing device, which has a central processing unit and a liquid crystal display, wherein the liquid crystal display includes a liquid crystal panel, a control circuit and a source driver circuit, and the central processing unit is Used to communicate with the control circuit, and the control circuit is used to execute a polarity change procedure, the polarity change procedure includes:

Dividing the frequency of a vertical synchronization signal by a reference frequency to generate a ratio M/N, where M is greater than N, and M and N are relatively prime positive integers; and

The source driving circuit is made to drive the liquid crystal panel in a way, the way is to change the polarity of the driving voltage N times during the driving process of every M frames of pictures.

Preferably, the period of the reference frequency is lower than the duration of vision.

In a possible embodiment, N=1 or greater than 1.

In a possible embodiment, the ratio can be obtained by means of software or hardware.

In a possible embodiment, the information processing device may be a smart phone, a portable computer, a vehicle computer, a wearable electronic device or an access control device.

In order to enable your review committee members to further understand the structure, features and purpose of the present invention, drawings and detailed descriptions of preferred specific embodiments are hereby attached.

Principle of the present invention is:

(1) Divide the frequency f of a variable vertical synchronization signal by a reference frequency f _REF to generate a ratio M/N, wherein, f is greater than or equal to f _REF , the period of f _REF is lower than the visual persistence time, and M is greater than N, and M and N are relatively prime positive integers; and

(2) Make a source drive circuit change the polarity of the driving voltage N times in the driving period M*T of every M frame picture according to the ratio M/N, T=1/f, so that the equivalent polarity changing period=(M *T)/N=(M/N)*T=(f/f _REF )*(1/f)=(1/f _REF ) seconds.

In addition, assuming that the equivalent capacitance of the liquid crystal panel is C, the present invention can limit the dynamic power consumption P _d generated by the polarity change to P _d =C*f _REF *(2V) ² , where 2V is the driving voltage and is determined by +V The voltage difference to -V or from -V to +V.

According to the above principle, the present invention can adaptively determine a frame period according to the frequency of a vertical synchronous signal to change the polarity of the driving voltage of a liquid crystal panel, thereby minimizing the loss of the liquid crystal panel during the polarity exchange process of the driving voltage. generated power consumption.

Please refer to FIG. 2 , which is a block diagram of an embodiment of the liquid crystal display of the present invention. As shown in Figure 2, a liquid crystal display 100 comprises a control circuit 110, a gate drive circuit 120, a source drive circuit 130 and a liquid crystal panel 140, wherein the control circuit 110 is used to control the gate drive circuit 120 and The source driving circuit 130 performs a display operation to enable the liquid crystal panel 140 to display a picture, the display operation includes a polarity change procedure, and the polarity change procedure includes:

(1) Dividing the frequency of a vertical synchronization signal V _SYNC by a reference frequency to generate a ratio M/N, where M is greater than N, and M and N are mutually prime positive integers; and

(2) Make the source driving circuit 130 drive the liquid crystal panel 140 according to a polarity switching mode, the polarity switching mode is to change the polarity of the driving voltage N times during the driving process of every M frames of pictures.

For example, assuming that the reference frequency is _60HZ , and the frequency of the vertical synchronization signal V _SYNC is _75HZ , then the ratio of it to the reference frequency is (75/60)=(5/4); at this time, the polarity conversion method is The polarity of the driving voltage is changed 4 times during the driving process of every 5 frames of pictures, and its equivalent polarity changing period=(5*1/75)/4=(1/60) seconds, please refer to Figure 3a for the schematic diagram. For another example, assuming that the frequency of the vertical synchronous signal V _SYNC is 120H _Z , then the ratio of it to the reference frequency is (120/60)=(2/1); at this time, the polarity conversion method is the driving of every 2 frames of pictures During the process, the polarity of the driving voltage is changed once, and the equivalent polarity change period = (2*1/120)/1=(1/60) seconds, please refer to Figure 3b for the schematic diagram. For another example, assuming that the frequency of the vertical synchronous signal V _SYNC is 150H _Z , then the ratio of it to the reference frequency is (150/60)=(5/2); at this time, the polarity conversion method is the driving of every 5 frames of pictures During the process, the polarity of the driving voltage is changed twice, and the equivalent polarity change period=(5*1/150)/2=(1/60) seconds, please refer to Figure 3c for the schematic diagram. In addition, the ratio can be obtained by means of software or hardware.

That is, assuming that the equivalent capacitance of the liquid crystal panel is C, no matter whether the frequency of the vertical synchronization signal V _SYNC is an integer multiple (N=1) or a non-integer multiple (N greater than 1) of the reference frequency f _REF , the present invention can The dynamic power consumption P _d generated by the polarity change of the liquid crystal display is limited to P _d =C* f _REF *(2V) ² , where 2V is the voltage difference between the driving voltage from +V to -V or from -V to +V.

According to the above description, the present invention proposes a polarity conversion method for a liquid crystal panel with a variable refresh rate. Please refer to FIG. 4 , which is a flowchart of an embodiment of a polarity changing method for a liquid crystal panel with a variable refresh rate of the present invention. As shown in Figure 4, the method includes: dividing the frequency of a vertical synchronization signal by a reference frequency to generate a ratio M/N, M is greater than N, and M and N are mutually prime positive integers (step a); and Make a source driving circuit change the polarity of the driving voltage N times during the driving process of every M frames of pictures (step b).

According to the above-mentioned method, when the frequency of the vertical synchronous signal is lowered from the reference frequency f _REF to the reference frequency f _REF according to the requirements of different applications, or raised from the reference frequency f _REF to change the refresh rate of the liquid crystal panel, the present invention A frame period can be correspondingly determined to limit the polarity switching frequency of the driving voltage of the liquid crystal panel to f _REF , so as to minimize the power consumption of the liquid crystal panel during the polarity switching of the driving voltage.

According to the above description, the present invention further provides an information processing device. Please refer to FIG. 5 , which shows a block diagram of an embodiment of the information processing device of the present invention. As shown in FIG. 5 , an information processing device 200 has a central processing unit 210 and a liquid crystal display 220 , wherein the liquid crystal display 220 is realized by the liquid crystal display 100 , and the central processing unit 210 is used for communicating with the liquid crystal display 220 . In addition, the information processing device 200 can be a smart phone, a portable computer, a vehicle computer, a wearable electronic device or an access control device.

With the design disclosed above, the present invention has the following advantages:

1. The polarity changing method of a liquid crystal panel with a variable refresh rate of the present invention can adaptively determine a frame period by detecting the frequency of a vertical synchronous signal to change the polarity of a driving voltage of a liquid crystal panel, thereby minimizing the The power consumption generated by the liquid crystal panel during the polarity exchange of the driving voltage.

2. The liquid crystal display of the present invention can minimize the power consumption caused by the polarity transformation by using the above-mentioned polarity transformation method when displaying images at a high refresh rate.

3. The information processing device of the present invention has the above-mentioned liquid crystal display to minimize the power consumption generated by the polarity transformation by the above-mentioned polarity transformation method when displaying images at a high refresh rate.

What is disclosed in this case is a preferred embodiment. For example, any partial changes or modifications derived from the technical ideas of this case and easily deduced by those who are familiar with the technology are within the scope of the patent right of this case.

To sum up, regardless of the purpose, means and efficacy of this case, it shows that it is very different from the conventional technology, and its first invention is practical, and it does meet the patent requirements of the invention. I implore your review committee to understand it clearly and grant a patent as soon as possible. Society is for the Most Prayer.

100: liquid crystal display 110: control circuit 120: Gate drive circuit 130: Source drive circuit 140: LCD panel 200: information processing device 210: central processing unit 220: liquid crystal display Step a: Divide a frequency of a vertical synchronization signal by a reference frequency to generate a ratio M/N, where M is greater than N, and M and N are relatively prime positive integers. Step b: Make a source driving circuit change the polarity of the driving voltage N times during the driving process of every M frames of pictures.

FIG. 1 illustrates a common polarity exchange method of a liquid crystal panel. FIG. 2 is a block diagram of an embodiment of the liquid crystal display of the present invention. 3a-3c illustrate a polarity conversion method of the liquid crystal display shown in FIG. 2, respectively. FIG. 4 is a flowchart of an embodiment of a polarity conversion method of a liquid crystal panel with a variable refresh rate according to the present invention. FIG. 5 is a block diagram of an embodiment of an information processing device of the present invention.

Step a: divide the frequency of a vertical synchronization signal by a reference frequency to generate a ratio M/N, M is greater than N, and M and N are positive integers that are relatively prime

Step b: Make a source driving circuit change the polarity of the driving voltage N times during the driving process of every M frames of pictures

Claims (10)

A method for changing the polarity of a liquid crystal panel with a variable refresh rate, comprising: dividing the frequency of a vertical synchronization signal by a reference frequency to generate a ratio M/N, where M is greater than N, and M and N are mutually prime positive integers, And M/N is not an even number; and a source driving circuit changes the polarity of the driving voltage N times during the driving process of every M frames of pictures; wherein, the cycle of the reference frequency is lower than the persistence of vision time. The polarity conversion method of a liquid crystal panel with a variable refresh rate as described in item 1 of the scope of the patent application, wherein N=1 or greater than 1. The polarity conversion method of a liquid crystal panel with a variable refresh rate as described in item 1 of the scope of the patent application, wherein the ratio is obtained by means of software or hardware. A liquid crystal display, which includes a liquid crystal panel, a control circuit and a source drive circuit, wherein the control circuit is used to execute a polarity change procedure, the polarity change procedure includes: dividing the frequency of a vertical synchronous signal by a The reference frequency is to generate a ratio M/N, M is greater than N, and M and N are mutually prime positive integers, and M/N is a non-even number; and the source drive circuit drives the liquid crystal panel according to a polarity conversion method, The polarity changing method is to change the polarity of the driving voltage N times during the driving process of every M frames of pictures; wherein, the cycle of the reference frequency is lower than the persistence of vision time. The liquid crystal display as described in claim 4 of the scope of application, wherein N=1 or greater than 1. The liquid crystal display as described in item 4 of the scope of the patent application, wherein the ratio is obtained by means of software or hardware. An information processing device, which has a central processing unit and a liquid crystal display, wherein the liquid crystal display includes a liquid crystal panel, a control circuit and a source driver circuit, the central processing unit is used to communicate with the control circuit, and The control circuit is used to execute a polarity changing procedure, and the polarity changing procedure includes: dividing the frequency of a vertical synchronization signal by a reference frequency to generate a ratio M/N, where M is greater than N, And M, N are mutually prime positive integers, and M/N is a non-even number; and make the source drive circuit drive the liquid crystal panel in a way, the way is to change the driving voltage during the driving process of every M frame picture Polarity N times; wherein, the period of the reference frequency is lower than the duration of vision. The information processing device as described in item 7 of the patent application, wherein N=1 or greater than 1. The information processing device as described in item 7 of the patent application, wherein the ratio is obtained by means of software or hardware. The information processing device described in item 7 of the scope of the patent application is one selected from the group consisting of a smart phone, a portable computer, a vehicle-mounted computer, a wearable electronic device and an access control device device.

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