TWI742683B - Liquid crystal display device and driving method thereof - Google Patents

Abstract

A liquid crystal display device and a driving method thereof are provided. The liquid crystal display device includes a liquid crystal display panel and a drive circuit. The driving circuit is coupled to the liquid crystal display panel, and receives a frame information signal indicating a frame rate and a driving instruction signal indicating an inversion method from a host outside the liquid crystal display device. The driving circuit determines whether the frame rate changes based on the frame information signal, and when the frame rate changes and a number of frames of the frame rate change reaches a predetermined number cumulatively, the driving circuit drives the liquid crystal display panel in a first inversion manner fixedly, wherein the predetermined number is greater than or equal to 2.

Description

Liquid crystal display device and driving method thereof

The present invention relates to a display device, and more particularly to a liquid crystal display device and a driving method thereof.

The liquid crystal display device is the most mature and widely used display among many flat panel display devices. It has been industrialized and is still developing rapidly. Due to a series of irreplaceable advantages of the liquid crystal itself and the development of related technologies, the liquid crystal display device will occupy an increasing proportion in the display device market. At present, the liquid crystal display device uses an automatic switching method of driving polarity to solve the abnormal picture caused by some special patterns. However, due to the algorithm, in some dynamic pictures, the picture will continuously switch between different polarity inversion driving modes, which will produce flicker and other abnormalities that can be detected by the human eye, which will affect the quality of the display.

The invention provides a liquid crystal display device and a driving method thereof, which can avoid continuous switching of images between different polarity inversion driving modes and stabilize the display quality of the liquid crystal display device.

The liquid crystal display device of the present invention includes a liquid crystal display panel and a driving circuit. The driving circuit is coupled to the liquid crystal display panel, and receives a picture information signal indicating a picture update rate and a driving instruction signal indicating a reversal mode from a host outside the liquid crystal display device. The driving circuit judges whether the picture update rate is changed based on the picture information signal, and when the picture update rate changes and the number of pictures with the change of the picture update rate accumulates to a predetermined number, the driving circuit fixedly drives the liquid crystal display panel in the first inversion mode, wherein the predetermined The number is greater than or equal to 2.

The driving method of the liquid crystal display device of the present invention includes the following steps. The driving circuit of the liquid crystal display device receives a picture information signal indicating the picture update rate and a driving instruction signal indicating the inversion mode from the host outside the liquid crystal display device. The driving circuit determines whether the picture update rate changes based on the picture information signal. When the frame update rate changes, the driving circuit counts the number of frames whose frame update rate changes. When the frame update rate changes and the accumulation reaches a predetermined number, the driving circuit will drive the liquid crystal display panel in a first inversion mode, where the predetermined number is greater than or equal to 2.

Based on the above, the liquid crystal display device and the driving method thereof according to the embodiments of the present invention, when the screen update rate changes and accumulates to a predetermined number, the driving circuit can fixedly drive the liquid crystal display panel in the first inversion mode to avoid/suppress frequent The switching of the reverse mode causes an abnormality in the image display.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail in conjunction with the accompanying drawings.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having meanings consistent with their meanings in the context of related technologies and the present invention, and will not be interpreted as idealized or excessive The formal meaning, unless explicitly defined as such in this article.

It should be understood that although the terms "first", "second", "third", etc. may be used herein to describe various elements, components, regions, layers and/or parts, these elements, components, regions, and/or Or part should not be restricted by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Therefore, the "first element", "component", "region", "layer" or "portion" discussed below may be referred to as a second element, component, region, layer or section without departing from the teachings herein.

The terminology used here is only for the purpose of describing specific embodiments and is not restrictive. As used herein, unless the content clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include the plural forms, including "at least one." "Or" means "and/or". As used herein, the term "and/or" includes any and all combinations of one or more of the related listed items. It should also be understood that when used in this specification, the terms "including" and/or "including" designate the presence of the features, regions, wholes, steps, operations, elements, and/or components, but do not exclude one or more The existence or addition of other features, regions as a whole, steps, operations, elements, components, and/or combinations thereof.

FIG. 1 is a system schematic diagram of a liquid crystal display device according to an embodiment of the invention. 1, in this embodiment, the liquid crystal display device 100 includes a driving circuit 110 and a liquid crystal display panel 120, and the driving circuit 110 includes, for example, a timing controller 111, a source driver 112, and a gate driver 113. The timing controller 111 of the driving circuit 110 is coupled to the host 10 outside the liquid crystal display device 100 to receive from the host 10 a screen information signal SFI indicating a screen update rate and a driving instruction signal SDI indicating an inversion mode.

The source driver 112 and the gate driver 113 of the driving circuit 110 are respectively coupled between the timing controller 111 and the liquid crystal display panel 120. The timing controller 111 responds to the screen information signal SFI to provide a control signal Sctrl1 to the gate driver 113 to control the gate driver 113 to provide a plurality of sequentially enabled gate signals Gx to the liquid crystal display panel 120. In addition, the timing controller 111 responds to the screen information signal SFI and the driving instruction signal SDI to provide a control signal Sctrl2 and display data SDX to the source driver 112 to control the source driver 112 to provide a plurality of pixel voltages Vdp to the liquid crystal display panel 120.

The liquid crystal display panel 120 responds to the received pixel voltage Vdp to determine the inversion mode of the liquid crystal and the degree of light transmission of the liquid crystal to determine the image displayed by the liquid crystal display panel 120.

In this embodiment, the timing controller 111 of the driving circuit 110 determines whether the frame update rate has changed based on the screen information signal SFI, and when the frame update rate changes and the number of frames of the frame update rate change accumulates to a predetermined number, the drive circuit The timing controller 111 of the 110 drives the liquid crystal display panel 120 in the first inversion mode CNV1 fixedly, wherein the predetermined number is greater than or equal to two. When the frame update rate has not changed or the cumulative number of frames with the frame update rate has reached a predetermined number, the driving circuit 110 drives the liquid crystal display panel in one of the first inversion mode CNV1 and the second inversion mode CNV2 based on the drive instruction signal SDI 120.

According to the above, when the screen update rate changes, it means that the screen processing of the host 10 may be in an abnormal state (for example, the screen judgment is at a critical point), that is, the drive instruction signal SDI may frequently indicate the switching of the inversion mode, so the timing controller 111 can fixedly drive the liquid crystal display panel 120 in the first inversion mode CNV1 to avoid/suppress frequent switching of the inversion mode to cause abnormal image display.

In the embodiment of the present invention, the first inversion mode CNV1 is, for example, a dot inversion mode. The second inversion mode CNV2 is, for example, one of vertical double dot inversion, 2*2 matrix dot inversion+1, and horizontal double dot inversion. Also, the picture information signal SFI may include a vertical synchronization signal Vsgnc.

FIG. 2 is a schematic diagram of a waveform of a vertical synchronization signal according to an embodiment of the invention. Please refer to FIG. 1 and FIG. 2. In this embodiment, the timing controller 111 determines whether the picture update rate changes, for example, according to the vertical synchronization signal Vsgnc. In the screen periods F0, F2, F5, F8 and F10, the time lengths of the screen periods F0, F2, F5, F8 and F10 are all 1T, which means that the screen update rate has not changed; the screen periods F1, F3, F4, F6, F7 In F9, the time length of the screen periods F1, F3, F4, F6, F7, F9 is greater than 1T, which means that the screen update rate has changed.

In this embodiment, based on the screen period F1 during which the screen update rate changes, the timing controller 111 starts to accumulate the number of screens with the screen update rate change, that is, starts counting at the time point TS, and assumes that the predetermined time for counting is 10 screen periods , That is, the counting ends at the time point TE. The predetermined number here is 5 as an example. The number of screens whose screen update rate changes is 6 (that is, the screen period F1, F3, F4, F6, F7, F9). Therefore, after the time point TE, the timing controller 111 can be fixed. The liquid crystal display panel 120 is driven in the first inversion mode CNV1 for a period of time (for example, a period of 10 frames to a period of 100 frames) or it is determined whether the fixation can be released based on the screen information signal SFI.

Further, after the timing controller 111 can fixedly drive the liquid crystal display panel 120 in the first inversion mode CNV1, the timing controller 111 can determine the number of frames whose image update rate has not changed to determine whether to release the fixed inversion mode, and count The method is similar to the above, so I won't repeat it here.

In the above-mentioned embodiment, the timing controller 111 can determine that the frame update rate is greater than or equal to a critical value (for example, 20%) based on the screen information signal SFI. The screen update rate is considered to be changed when the rate decreases beyond a critical value (for example, 20%); on the contrary, the timing controller 111 can determine that the screen update rate does not exceed the critical value (for example, 20%) based on the screen information signal SFI. No change, that is, the timing controller 111 can consider that the screen update rate has not changed when the screen update rate is lowered and does not exceed a threshold value (for example, 20%). The above threshold value is 20% as an example, but in other embodiments, the threshold value may be between 10% and 30%, and the embodiment of the present invention is not limited thereto.

In the above embodiment, the timing controller 111 only activates one counting task, that is, after the counting is started, another counting cannot be performed before the counting is finished. However, in other embodiments, the timing controller 111 can enable multiple counting tasks (for example, more than two) to monitor the screen processing status of the host 10 at any time. This depends on the circuit design, and the embodiment of the present invention is not limited thereto. . In addition, the predetermined time in the foregoing embodiment uses 10 frame periods as an example, but in other embodiments, the predetermined time may be between 10 frame periods and 100 frame periods, and the embodiment of the present invention is not limited thereto.

FIG. 3A is a schematic diagram of a screen of a dot inversion method according to an embodiment of the present invention. Referring to FIG. 3A, in the dot inversion method of this embodiment, the polarity of each pixel of the liquid crystal display device 100 is different from the polarity of adjacent pixels.

FIG. 3B is a schematic diagram of a screen of a vertical double dot inversion method according to an embodiment of the present invention. Referring to FIG. 3B, in the vertical double dot inversion method of this embodiment, the polarities of two adjacent pixels in each row of the liquid crystal display device 100 are the same, but the polarities of the adjacent pixels are different.

FIG. 3C is a schematic diagram of a horizontal double dot inversion method according to an embodiment of the present invention. Referring to FIG. 3C, in the horizontal double-dot inversion method of this embodiment, the polarities of two adjacent pixels in each column of the liquid crystal display device 100 are the same, but the polarities of the adjacent pixels are different.

FIG. 3D is a schematic diagram of a 2*2 matrix dot inversion method according to an embodiment of the present invention. Referring to FIG. 3D, in the 2*2 matrix dot inversion method of this embodiment, the polarities of adjacent 2*2 pixels in the liquid crystal display device 100 are the same, but the polarities of adjacent pixels are different.

4 is a flowchart of a driving method of a liquid crystal display device according to an embodiment of the invention. Referring to FIG. 4, in this embodiment, the driving method of the liquid crystal display device includes the following steps. In step S410, the driving circuit of the liquid crystal display device receives a picture information signal indicating the picture update rate and a driving instruction signal indicating the inversion mode from a host outside the liquid crystal display device. In step S420, the driving circuit determines whether the picture update rate has changed based on the picture information signal. When the screen update rate changes, that is, when the judgment result of step S420 is YES, step S430 is executed. In step S430, the driving circuit counts the number of screens whose screen update rate has changed. When the cumulative number of screens whose screen update rate has changed reaches a predetermined number, step S440 is executed. In step S450, the liquid crystal display panel is fixedly driven by the driving circuit in the first inversion mode, wherein the predetermined number is greater than or equal to.

When the screen update rate has not changed, that is, when the judgment result of step S420 is no, step S450 is executed. In addition, when the cumulative number of screens whose screen update rate has changed has not reached the predetermined number, step S450 is executed. In step S450, the driving circuit drives the liquid crystal display panel in one of the first inversion mode and the second inversion mode based on the driving instruction signal. Among them, the details of the above steps S410, S420, S430, S440, and S450 can be referred to the embodiment of FIG. 1 and FIG. 2, which will not be repeated here. Moreover, the sequence of the above steps S410, S420, S430, S440, and S450 is for illustration, and the embodiment of the present invention is not limited thereto.

To sum up, in the liquid crystal display device and the driving method thereof according to the embodiments of the present invention, when the frame update rate changes and the accumulation reaches a predetermined number, the driving circuit can drive the liquid crystal display panel in the first inversion mode fixedly to avoid/suppress Frequent switching of the reverse mode causes abnormal image display.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the relevant technical field can make some changes and modifications without departing from the spirit and scope of the present invention. The protection scope of the present invention shall be subject to those defined by the attached patent application scope.

10: host 100: Liquid crystal display device 110: drive circuit 111: timing controller 112: source driver 113: Gate Driver 120: LCD panel CNV1: The first reversal mode CNV2: The second reversal mode F0~F10: During the screen Gx: gate signal Sctrl1, Sctrl2: control signal SDI: Drive indicator signal SDX: display data SFI: Screen information signal TS, TE: point in time Vdp: pixel voltage Vsgnc: vertical sync signal S410, S420, S430, S440, S450: steps

FIG. 1 is a system schematic diagram of a liquid crystal display device according to an embodiment of the invention. FIG. 2 is a schematic diagram of a waveform of a vertical synchronization signal according to an embodiment of the invention. FIG. 3A is a schematic diagram of a screen of a dot inversion method according to an embodiment of the present invention. FIG. 3B is a schematic diagram of a screen of a vertical double dot inversion method according to an embodiment of the present invention. FIG. 3C is a schematic diagram of a horizontal double dot inversion method according to an embodiment of the present invention. FIG. 3D is a schematic diagram of a 2*2 matrix dot inversion method according to an embodiment of the present invention. 4 is a flowchart of a driving method of a liquid crystal display device according to an embodiment of the invention.

10: host

100: Liquid crystal display device

110: drive circuit

111: timing controller

112: source driver

113: Gate Driver

120: LCD panel

CNV1: The first reversal mode

CNV2: The second reversal mode

Gx: gate signal

Sctrl1, Sctrl2: control signal

SDI: Drive indicator signal

SDX: display data

SFI: Screen information signal

Vdp: pixel voltage

Claims (14)

A liquid crystal display device, comprising: a liquid crystal display panel; and a driving circuit, coupled to the liquid crystal display panel, and receiving a picture information signal indicating a picture update rate and indicating a reversal from a host outside the liquid crystal display device A driving instruction signal of the method, wherein the driving circuit determines whether the frame update rate is changed based on the frame information signal, and when the frame update rate changes and the number of frames of the frame update rate changes cumulatively reaches a predetermined number, the The driving circuit fixedly drives the liquid crystal display panel in a first inversion mode, wherein the predetermined number is greater than or equal to 2. When the variation of the frame update rate is greater than or equal to a critical value, the driving circuit determines the frame based on the frame information signal The update rate changes. When the variation of the frame update rate is less than the critical value, the driving circuit determines that the frame update rate has not changed based on the frame information signal. The liquid crystal display device according to claim 1, wherein the first inversion mode is a one-point inversion mode. The liquid crystal display device according to claim 1, wherein when the frame update rate has not changed or the number of frames whose frame update rate has changed cumulatively reaches a predetermined number, the driving circuit performs the first inversion based on the driving instruction signal And a second inversion method to drive the liquid crystal display panel. The liquid crystal display device according to claim 3, wherein the second inversion mode includes one of a vertical double dot inversion, a 2*2 matrix dot inversion+1, and a horizontal double dot inversion. The liquid crystal display device according to claim 1, wherein each time a change in the screen update rate is detected, the number of the screen with the change in the screen update rate starts to accumulate, and the screen update rate is within a predetermined time after the start of counting When the number of changing frames reaches the predetermined number, the driving circuit drives the liquid crystal display panel in the first inversion mode, wherein the predetermined time is between 10 frame periods and 100 frame periods. The liquid crystal display device according to claim 1, wherein the picture information signal includes a vertical synchronization signal. The liquid crystal display device according to claim 1, wherein the threshold is between 10% and 30%. A driving method of a liquid crystal display device includes: a driving circuit of a liquid crystal display device receives from a host outside the liquid crystal display device a picture information signal indicating a picture update rate and a driving instruction signal indicating a reversal mode ; The drive circuit determines whether the screen update rate has changed based on the screen information signal; when the screen update rate changes, the drive circuit counts the number of frames with the change in the screen update rate; when the screen update rate changes and the accumulation reaches When a predetermined number is reached, the driving circuit will drive the liquid crystal display panel in a first inversion mode, wherein the predetermined number is larger Is equal to 2, wherein the step of determining whether the image update rate is changed by the driving circuit based on the image information signal includes: when the variation of the image update rate is greater than or equal to a threshold value, the driving circuit determines the image based on the image information signal The frame update rate changes; and when the variance of the frame update rate is less than the critical value, the driving circuit determines that the frame update rate has not changed based on the frame information signal. The driving method according to claim 8, wherein the first inversion mode is a one-point inversion mode. The driving method according to claim 8, further comprising: when the frame update rate has not changed or the number of frames whose frame update rate has changed cumulatively reaches a predetermined number, the driving circuit uses the first drive instruction signal based on the drive instruction signal. One of an inversion mode and a second inversion mode drives the liquid crystal display panel. The driving method according to claim 10, wherein the second inversion mode includes one of a vertical double dot inversion, a 2*2 matrix dot inversion+1, and a horizontal double dot inversion. The driving method according to claim 8, wherein the step of counting, by the driving circuit, the number of frames whose frame update rate has changed includes: counting by the driving circuit the number of frames whose frame update rate has changed within a predetermined time reaches the predetermined number of frames. When counting, when the number of screens whose screen update rate changes within a predetermined time after the start of accumulation reaches the predetermined number, the drive circuit will drive the liquid in the first inversion mode fixedly. The crystal display panel, wherein the predetermined time is between 10 frame periods and 100 frame periods. The driving method according to claim 8, wherein the image information signal includes a vertical synchronization signal. The driving method according to claim 8, wherein the critical value is between 10% and 30%.

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