TWI423237B - Driving method of lcd panel - Google Patents

Description

Driving method of liquid crystal display panel

The present invention relates to a driving method, and in particular to a driving method of a liquid crystal display panel.

With the advancement of modern video technology, liquid crystal display devices have been widely used in mobile phones, notebooks, personal computers (NCs), personal digital assistants (NDAs), etc. The display of consumer electronics is on the screen. However, since the liquid crystal display panel of the liquid crystal display device itself does not have the function of emitting light, it is necessary to configure the backlight module to provide a light source required for the liquid crystal display panel, thereby enabling the liquid crystal display panel to achieve the display effect. The backlights of the backlight modules on the market currently include flat fluorescent lamps, Cold Cathode Fluorescent Lamps (CCFLs), and Light Emitting Diodes (LEDs).

In general, when the backlight module is in operation, the light source generates heat energy, so that the temperature around the light source increases. The liquid crystal display panel is usually close to the backlight module, and changes in the temperature of the liquid crystal due to the characteristics of the liquid crystal, so that the display effect of the liquid crystal display panel changes. In the case of a direct-lit backlight module, the light source of the backlight module is evenly distributed behind the liquid crystal display panel. Therefore, the liquid crystal on the liquid crystal display panel is synchronously changed due to the temperature rise of the light source, so that the liquid crystal display panel is The change in display effect does not cause significant errors and affects the viewing effect.

In the case of a side-lit backlight module, the backlight source is usually disposed on one side or both sides of the liquid crystal display panel, and the liquid crystal may be different in temperature and temperature due to the distance from the backlight source. That is, the change in the liquid crystal display effect varies depending on the distance from the backlight source. Therefore, when the side-lit backlight module is in operation, the display effect of the liquid crystal display panel is not uniform. Especially when the liquid crystal display panel displays a dark state picture (such as a full black picture), the brightness of the liquid crystal close to the backlight source may be different from the brightness displayed by other parts of the liquid crystal display panel.

The present invention provides a driving method for determining the pixel voltage of each image grayscale value according to the degree of change in the characteristics of the liquid crystal when the liquid crystal of the liquid crystal display panel changes characteristics due to temperature changes, and thereby improving the in-plane of the panel. Evenness.

The present invention provides a driving method suitable for a liquid crystal display device, and the driving method includes the following steps. Receive picture data. Obtaining an image grayscale value corresponding to the target pixel according to the screen data, wherein the target pixel is one of a plurality of pixels of the liquid crystal display panel of the liquid crystal display device. The pixel voltage corresponding to the gray scale value of the image is determined according to the current temperature of the target pixel. Write the pixel voltage corresponding to the image grayscale value to the target pixel.

In an embodiment of the invention, the current temperature of the target pixel is determined by the shortest distance between the target pixel and the light-emitting elements of the backlight module of the liquid crystal display device.

In an embodiment of the invention, when the grayscale value of the image is less than or equal to the grayscale threshold, the grayscale value of the image corresponds to different pixel voltages in the target pixel of different current temperatures. When the image grayscale value is greater than the grayscale threshold, the image grayscale value corresponds to the same pixel voltage in the target pixel of different current temperatures.

In an embodiment of the present invention, the step of determining the pixel voltage corresponding to the grayscale value of the image according to the current temperature of the target pixel includes: when the current temperature of the target pixel is the first temperature, according to the first comparison The table obtains a first color grayscale value corresponding to the grayscale value of the image, and the grayscale value of the image is the voltage corresponding to the grayscale value of the first color as the corresponding pixel voltage; when the current temperature of the target pixel is the second temperature And obtaining, according to the second comparison table, a second color grayscale value corresponding to the grayscale value of the image, and the image grayscale value is a voltage corresponding to the second color grayscale value as its corresponding pixel voltage.

In an embodiment of the present invention, the step of determining a pixel voltage corresponding to the gray level value of the image according to the current temperature of the target pixel further includes: when the current temperature of the target pixel is between the first temperature and the second temperature The image grayscale value is interpolated by the first color grayscale value and the second color grayscale value to obtain a third color grayscale value, and the voltage corresponding to the third color grayscale value is used as the corresponding Pixel voltage.

In an embodiment of the present invention, when the grayscale value of the image is less than or equal to the grayscale threshold, the first color grayscale value is different from the second color grayscale value; when the grayscale value of the image is greater than the grayscale critical value, A color grayscale value is the same as the second color grayscale value.

In an embodiment of the invention, the above is based on the current pixel of the target The step of determining the pixel voltage corresponding to the grayscale value of the image includes: providing a plurality of first gamma voltages when the current temperature of the target pixel is the first temperature, and selecting one of the gamma voltages as the image a pixel voltage corresponding to the grayscale value; when the current temperature of the target pixel is the second temperature, providing a plurality of second gamma voltages, and selecting one of the second gamma voltages as the image grayscale value corresponding to Pixel voltage.

In an embodiment of the invention, the step of providing the first gamma voltage comprises: obtaining a plurality of first gamma reference voltages corresponding to the first temperature; performing voltage division according to the first gamma reference voltages to generate These first gamma voltages.

In an embodiment of the invention, the step of providing the second gamma voltage comprises: obtaining a plurality of second gamma reference voltages corresponding to the second temperature; performing voltage division according to the second gamma reference voltages to generate These second gamma voltages.

In an embodiment of the invention, the portion of the first gamma reference voltage is different from the portion of the second gamma reference voltage that corresponds to the same image grayscale value.

In an embodiment of the invention, the image grayscale value corresponding to the difference between the first gamma reference voltage and the second gamma reference voltage is less than or equal to the grayscale threshold.

In an embodiment of the present invention, the step of determining the pixel voltage corresponding to the grayscale value of the image according to the current temperature of the target pixel further includes: providing a plurality of current temperatures of the target pixel when the current temperature is the third temperature a third gamma voltage, and one of the gamma voltages is selected as a pixel voltage corresponding to the image grayscale value, wherein the third gamma voltage is based on the first gamma The voltage of the horse and the second gamma voltage are obtained by interpolation.

In an embodiment of the invention, when the image grayscale value is less than or equal to the grayscale threshold, the first gamma voltage corresponding to the grayscale value of the image is different from the second gamma voltage corresponding to the grayscale value of the image. When the image grayscale value is greater than the grayscale threshold, the first gamma voltage corresponding to the grayscale value of the image is the same as the second gamma voltage corresponding to the grayscale value of the image.

In an embodiment of the invention, the liquid crystal display panel is normally displayed in white.

In an embodiment of the invention, the liquid crystal display panel is normally displayed in black.

In an embodiment of the invention, the liquid crystal display panel is a twisted nematic liquid crystal display panel.

In an embodiment of the invention, the liquid crystal display panel is a vertical alignment type liquid crystal display panel.

Based on the above, the driving method of the present invention adjusts the pixel voltage corresponding to the grayscale value of the image corresponding to the pixel according to the current temperature of the pixel. Thereby, when the liquid crystal display panel is affected by the temperature of the light-emitting element, there is no significant difference in brightness when the dark state screen is displayed, thereby improving the in-plane uniformity of the liquid crystal display panel.

The above described features and advantages of the present invention will be more apparent from the following description.

1 is a system diagram of a liquid crystal display device in accordance with an embodiment of the present invention; intention. Referring to FIG. 1 , the liquid crystal display device 100 includes a liquid crystal display panel (LCD panel) 110 , light emitting elements 121 and 123 , a timing controller (T-con) 130 , a gate driver 140 , and a source driver. (source driver) 150, gamma voltage generator 160 and memory component 170, wherein a backlight module 120 is composed of light-emitting elements 121 and 123, and the light-emitting elements 121 and 123 can be flat fluorescent lamps. , Cold Cathode Fluorescent Lamp (CCFL) or Light Emitting Diode (LED).

In this embodiment, the timing controller 130 receives the video signal VS to control the gate driver 140 and the source driver 150 according to the picture data transmitted by the video signal VS. Moreover, the timing controller 130 outputs the color grayscale value CG according to the grayscale value of the image corresponding to the target pixel (such as pixels P1 to P6) to be written, according to the grayscale value of the image and the color of the target pixel. Source driver 150. The gate driver 140 is controlled by the timing controller 130, and each pixel (such as the pixel columns L1 to L6) in the liquid crystal display panel 110 is turned on one by one. The gamma voltage generator 160 obtains a plurality of gamma reference voltages corresponding to each pixel column from the memory element 170 according to the enable signal STV and the vertical clock signal CKV generated by the timing controller 130, and then these gamma reference The voltage is divided to generate a plurality of gamma voltages V _GM . Moreover, the gamma voltage generator 160 can further obtain a plurality of gamma reference voltages corresponding to each pixel according to the horizontal clock signal CKH to generate a plurality of gamma voltages V _GM .

The source driver 150 selects a gamma voltage V _GM as the pixel voltage VP of the write target pixel in accordance with the color gray scale value CG, and supplies it to each column of pixels in the liquid crystal display panel 110 that is turned on by the gate driver 140. The light-emitting elements 121 and 123 provide a surface light source required by the liquid crystal display panel 110. After the source driver 150 supplies the corresponding pixel voltage VP to the last column of pixels (such as the pixel column L6) in the liquid crystal display panel 110, the liquid crystal The display panel 110 can display the complete picture for the user to watch.

As shown in FIG. 1 , the light-emitting elements 121 and 123 of the backlight module 120 are respectively disposed on the upper side and the lower side of the liquid crystal display panel 110 , and also generate thermal energy when the light-emitting elements 121 and 123 provide a light source, so that the liquid crystal display panel 110 The temperature of the middle part of the liquid crystal will rise. Here, it is assumed that the liquid crystals of the pixel columns L1 and L2 sense the heat energy generated by the light-emitting element 121 to increase the temperature, and the liquid crystals of the pixel columns L5 and L6 sense the heat energy generated by the light-emitting element 123 to raise the temperature. The temperatures of the liquid crystals of the columns L3 and L4 are not affected by the heat energy generated by the light-emitting elements 121 and 123. Since the pixel sequence L1 is closer to the light-emitting element 121, the temperature change of the liquid crystal in the pixel column L1 is higher than the temperature change of the liquid crystal in the pixel column L2, that is, the liquid crystal of the shortest distance from the light-emitting element 121 is felt. Different thermal gradients have different temperature changes. In other words, the temperature change of the liquid crystal in the pixel column L6 is higher than the temperature change of the liquid crystal in the pixel column L5.

In general, the characteristics of the light-emitting elements 121 and 123 are different, that is, the temperature changes of the liquid crystals in the pixel columns L1 and L6 are different, but in the case where the difference width is too small, the temperature of the liquid crystal in the pixel columns L1 and L6 is different. The degree of change can be considered the same. Similarly, each of the light-emitting elements 121 and 123 is The generated thermal energy may also be different. Therefore, there is a difference in the temperature change of the liquid crystal of each pixel in L1 and L6, but in the case where the difference is not obvious, each of the pixels L1 and L6 The degree of temperature change of the liquid crystal of the pixel can be regarded as the same.

Further, since the characteristics of the liquid crystal in the pixel columns L1, L2, L5, and L6 change due to the temperature rise, the display effect of the liquid crystal in the pixel columns L1, L2, L5, and L6 also changes. In other words, the liquid crystals in the pixel columns L1, L2, L5, and L6 change the relationship between the transmittance and the pixel voltage VP due to the increase in the current temperature. Therefore, the display effects of the upper and lower sides and the center of the liquid crystal display panel 110 are different. In particular, when displaying a dark state picture (such as a pure black picture), since the displayed color is relatively simple, the brightness displayed on the upper and lower sides of the liquid crystal display panel 110 is significantly different from the brightness displayed in the central portion, and the difference in brightness It will be proportional to the thermal gradient felt by each liquid crystal.

In this case, the correspondence between the plurality of image gray scale values corresponding to each pixel column and the pixel voltage VP can be adjusted according to the distance between the pixel columns L1, L2, L5, and L6 and the light-emitting elements 121 and 123, that is, The pixel voltage VP corresponding to each image grayscale value is determined according to the current temperature of the pixel columns L1, L2, L5, and L6, so as to adjust the penetration of the liquid crystal of each pixel in the liquid crystal display panel 110 corresponding to the same image grayscale value. The rates are similar or the same. The pixel voltage VP can be completed by changing the color grayscale value CG or the gamma voltage V _GM , and the implementation manner is as follows.

2 is a characteristic diagram of a twisted nematic (TN) type liquid crystal according to an embodiment of the present invention. Please refer to Figure 1 and Figure 2, In the present embodiment, the liquid crystal display panel 110 is an example of a normally white twisted nematic liquid crystal panel, wherein the curve 210 is a liquid crystal reaction curve at a normal temperature, and the curve 220 is a liquid crystal reaction curve at a high temperature. And the curve 210 can correspond to the pixel columns L3 and L4, and the curve 220 can correspond to the pixel columns L1 and L6. As can be seen from the figure, in the normal temperature state, the liquid crystal has no transmittance at the voltage V1, that is, the liquid crystal gradation value CG is 0 when the pixel voltage VP is the voltage V1. In the high temperature state, the liquid crystal has no transmittance at the voltage V2, that is, the liquid crystal gray level value CG is 0 when the pixel voltage VP is the voltage V2, and the liquid crystal still has penetration when the pixel voltage VP is the voltage V1. The rate, here assumed that the color gradation value CG corresponding to the transmittance at the voltage V1 is 5.

Here, how to adjust the pixel voltage VP by adjusting the color grayscale value CG will be described first. Referring to FIG. 1, in the timing controller 130, a color grayscale value CG corresponding to each image grayscale value is obtained through a white balance tracking comparison table (such as the comparison tables 1 and 2). Wherein, since the same color grayscale value CG is different in brightness displayed by different colors, in order to enable the brightness required for displaying the grayscale value of the image in different colors, the image grayscale value is converted into a corresponding white balance tracking table. The color grayscale value CG is such that the target pixel can display the brightness of the image grayscale value to be displayed.

Moreover, in order to improve the accuracy of the grayscale value of the color grayscale value CG, the resolution of the color grayscale value CG may be higher than the resolution of the grayscale value of the image. In this embodiment, the white balance tracking comparison table is used to explain the adjustment mode of the pixel voltage VP, so only the white balance tracking comparison table of a single color is taken as an example, and the color grayscale value CG is represented by 10 bits, and the image is displayed. Gray scale values are expressed in 8-bit units. According to the above, the comparison tables 1 and 2 correspond to the same color, and it is assumed here that the comparison table 1 corresponds to the pixel columns L1 and L6, and the comparison table 2 corresponds to the pixel columns L3 and L4.

Since the pixel sequences L1 and L6 have a pixel gray voltage value of 5 at a normal temperature when the pixel voltage VP is a voltage V1 (that is, a pixel voltage VP corresponding to a color grayscale value of 0), that is, When the grayscale value of the image is displayed as 0, the pixel voltage VP written by the pixels of the pixel columns L1 and L6 at the high temperature (ie, the first temperature) corresponds to the color grayscale value of 0, and is at normal temperature (ie, the second temperature). The pixel of the pixel sequence L3 and L4 is the color gradation value 5 corresponding to the written pixel voltage VP, so that the pixels of the pixel columns L1, L3, L4, and L6 of the liquid crystal display panel 110 display the grayscale value of the image. 0 will show similar or phase The same brightness.

Therefore, the color grayscale value CG corresponding to the image grayscale value 0 in Table 1 is 0, and the color grayscale value CG corresponding to the image grayscale value 0 in Table 2 is 5. Moreover, the color grayscale values CG of the corresponding image grayscale values 1 in the comparison tables 1 and 2 are adjusted to be 4 and 7, respectively, so that the pixels of the pixel columns L1, L3, L4, and L6 are displayed in the grayscale value of the image 1 Similar or identical brightness will be displayed. The rest can be referred to the comparison tables 1 and 2, and will not be described again. Also, assuming that the comparison table 1 is a standard white balance tracking comparison table, the comparison table 2 is an adjusted white balance tracking comparison table.

Further, when the color grayscale value CG corresponding to the pixel voltage VP written by the pixels of the pixel columns L2 and L4 is determined, the temperature of the pixels of the pixel columns L2 and L4 is between the pixel columns L1 and L6. Between the pixel sequence L3 and L4, the interpolation operation can be performed according to the corresponding color grayscale value CG in the comparison tables 1 and 2, and the color grayscale value CG obtained according to the calculation result is used as the write pixel column L2 and The pixel voltage VP of the L4 medium pixel corresponds to the color gray scale value CG. For example, when the grayscale value of the image is displayed as 0, the pixels of the pixel columns L2 and L4 are written to the pixel voltage VP corresponding to the color grayscale value CG of 2.5 (ie, (0+5)/2), and the rest. Image grayscale values are analogous.

In other words, when the target pixel is the pixel P1 or P6, the color grayscale value CG corresponding to the grayscale value of the image is obtained according to the comparison table 1, and the voltage corresponding to the grayscale value CG of the color is used as the grayscale value of the image. Pixel voltage VP. When the target pixel is the pixel P3 or P4, the color grayscale value CG corresponding to the grayscale value of the image is obtained according to the comparison table 2, and the voltage corresponding to the grayscale value CG of the color is used as the pixel corresponding to the grayscale value of the image. Voltage VP. When the target When the pixel is a pixel P2 or P4, two color grayscale values CG are obtained according to the comparison table 1, 2 and the image grayscale value, and an interpolation operation is performed to obtain a corresponding color grayscale value CG, and the corresponding color is obtained. The voltage of the grayscale value CG is used as the pixel voltage VP corresponding to the image grayscale value.

Therefore, when the liquid crystal display panel 110 displays a screen, the brightness displayed by the center and the upper and lower sides at the same image gray scale value may be similar or the same, thereby improving the in-plane uniformity of the liquid crystal display panel 110, and may not be lowered. In the case of contrast, the in-plane uniformity of the liquid crystal display panel 110 is improved.

It is worth mentioning that since the difference in brightness is more obvious in the dark state, the table 2 can only correct the dark portion. Here, the image grayscale value 5 is used as the grayscale threshold value of whether it is a dark state, so the comparison table 2 can only correct the color grayscale value CG corresponding to the image grayscale value 0~5, so that the comparison table 1 and 2 The image grayscale values 0~5 correspond to different color grayscale values CG, and the portion of the comparison table 2 that is larger than the image grayscale value 5 can be the same as that of the comparison table 1. That is to say, in the portion where the grayscale value of the image is less than or equal to the grayscale threshold value of 5, each image grayscale value corresponds to a different pixel voltage VP in pixels of different temperatures; the grayscale value of the image is greater than the grayscale critical value. In the portion of 5, the grayscale value of each image corresponds to the same pixel voltage VP in pixels of different temperatures.

The following explains how to adjust the pixel voltage VP by adjusting the gamma voltage V _GM , and since the gamma voltage V _GM can be obtained by the gamma curve, the effect of adjusting the gamma voltage V _GM is like adjusting the gamma curve. 3 is a schematic diagram of a system in which a gamma voltage generator is coupled to a memory element in accordance with an embodiment of the invention. Referring to FIG. 3, the gamma voltage generator 160 is composed of a voltage generating unit 410 and a voltage dividing unit 420.

The voltage generating unit 410 obtains the corresponding gamma reference voltages VR1 VR12 and VR12 of each pixel column and the common voltage Vcom from the memory element 170 according to the start signal STV and the vertical clock signal CKV, or according to the start signal STV and the vertical clock signal. The CKV and the horizontal clock signal CKH acquire the corresponding gamma reference voltages VR1 to VR12 and the common voltage Vcom of each pixel from the memory element 170. Moreover, the voltage generating unit 410 outputs the gamma reference voltages VR1 VRVR12 and the common voltage Vcom to the voltage dividing unit 420 to perform voltage division by the voltage dividing unit 420 to generate a plurality of gamma voltages V _GM . Wherein, the gamma reference voltage VR1 is a negative voltage corresponding to the color grayscale value 0 (as indicated by the parenthesis, marked as -0), and the gamma reference voltage VR2 is a negative voltage corresponding to the color grayscale value 4 (as indicated by the brackets, Marked as -4), the rest is understood by reference to the illustration. For convenience of explanation, here, the resolution of the assumed color grayscale value CG is the same as the image grayscale value, that is, the resolution of the color grayscale value CG is exemplified by 8 bits, and the image grayscale value corresponds thereto. The color grayscale value CG is the same value.

Referring to FIG. 1 , FIG. 2 and FIG. 3 , according to the above, in the normal temperature state, the liquid crystal has no transmittance at the voltage V1 (that is, the image gray scale value is 0), and in the high temperature state, the liquid crystal does not have the voltage V2. The transmittance (i.e., the image grayscale value is 0), wherein the voltage V1 is assumed to be 5 volts and the voltage V2 is 5.3 volts. Therefore, if the pixel of the pixel columns L1 and L6 at high temperature is to be written with the pixel voltage VP, the voltage range of the gamma voltage V _GM is set to 0 to 5.3 volts, that is, the corresponding color gray scale. The gamma reference voltages VR6 and VR7 with a value of 255 are 0 volts, the gamma reference voltages VR1 and VR12 corresponding to the color grayscale value 0 are 5.3 volts, and the gamma reference voltages VR2 to VR5 and VR8 to VR11 are based on this voltage range and corresponding The color grayscale value CG determines its voltage value.

In addition, if the pixel of the pixel columns L3 and L4 at normal temperature is to be written into the pixel voltage VP, the voltage range of the gamma voltage V _GM is set to 0 to 5 volts, that is, the corresponding color gray scale. The gamma reference voltages VR6 and VR7 of value 255 are 0 volts, the gamma reference voltages VR1 and VR12 corresponding to the color gray scale value 0 are 5 volts, and the gamma reference voltages VR2 VR5 and VR8 VR11 are also based on this voltage range and The corresponding color grayscale value CG determines its voltage value.

To write the pixel voltage VP to the pixels of the pixel columns L3 and L4 between the normal temperature and the high temperature, the voltage range of the gamma voltage V _GM can be set to 0 to 5.15 volts, that is, The gamma reference voltages VR6 and VR7 corresponding to the color grayscale value 255 are 0 volts, the gamma reference voltages VR1 and VR12 corresponding to the color grayscale value 0 are 5.15 volts, and the gamma reference voltages VR2 to VR5 and VR8 to VR11 are also based on This voltage range and the corresponding color grayscale value CG determine its voltage value. In other words, the pixel current corresponding to the temperature of the high temperature and the gamma voltages V _GM gamma voltage corresponding to a normal V _GM is to be written based on the gamma interpolation calculation to obtain the temperature corresponding to the current pixel is to be written Voltage V _GM .

The voltage value is stored in the memory component 170, and the voltage generating unit 410 obtains a corresponding plurality of voltage values as the gamma reference voltages VR1 to VR12 according to the current temperature of each pixel column. Therefore, since the gamma voltage V _GM determines the voltage value according to the current temperature of the pixel column, when the liquid crystal display panel 110 displays the screen, the brightness displayed by the center and the upper and lower sides at the same image gray scale value is similar. Or the same, thereby improving the in-plane uniformity of the liquid crystal display panel 110.

As described above, since the difference in luminance of the liquid crystal display panel 110 when displaying a dark state picture is relatively remarkable, only the portion displaying the dark state can be corrected. Here, the color grayscale value 4 is used as the grayscale threshold value of whether it is a dark state, so only the gamma reference voltages VR1, VR2, VR11, and VR12 corresponding to each pixel column can be adjusted so that the corresponding pixel column L3 and L4 gamma reference voltages VR1, VR2, VR11 and VR12, gamma reference voltages VR1, VR2, VR11 and VR12 of corresponding pixel columns L2 and L5, and gamma reference voltages VR1, VR2 of corresponding pixel columns L1 and L6 The voltage values of the same gamma reference voltages in VR11 and VR12 are different from each other. That is to say, in the portion where the color grayscale value CG is less than or equal to the grayscale threshold value 4, each color grayscale value CG corresponds to a different pixel voltage VP in pixels of different temperatures; the color grayscale value CG is greater than gray. For the portion of the threshold value 4, each color grayscale value CG corresponds to the same pixel voltage VP in pixels of different temperatures.

In addition, since the light-emitting elements 121 and 123 do not immediately generate a large amount of thermal energy at the beginning of the liquid crystal display device 100, the temperature of the light-emitting elements 121 and 123 is maintained at a normal temperature, and the temperature is measured through the temperature sensor. To be done. At this time, the liquid crystal in the liquid crystal display panel 110 is not affected by the temperature and changes its characteristics, that is, the liquid crystal display panel 110 does not have a brightness difference when displaying a dark state picture. Moreover, a temperature threshold can be set to determine whether the thermal energy generated by the light-emitting elements 121 and 123 affects the liquid crystal in the liquid crystal display panel 110, and the liquid crystal display panel 110 has a significant difference in the brightness of the display dark state screen. That is, in a liquid crystal display device Before the temperature of the light-emitting elements 121 and 123 reaches the temperature threshold value, it is not necessary to adjust the pixel voltage VP corresponding to each image gray scale value according to the temperature of the target pixel, that is, each image gray scale Values in different temperatures correspond to the same pixel voltage VP.

After the liquid crystal display device 100 is activated for a while, it is assumed that the temperature of the light-emitting elements 121 and 123 exceeds the temperature threshold value, and at this time, the pixel voltage VP corresponding to each image grayscale value in the dark state portion is adjusted according to the temperature of the target pixel. . That is to say, when the temperature of the light-emitting elements 121 and 123 exceeds the temperature threshold, in the portion where the image grayscale value is less than or equal to the grayscale threshold, each image grayscale value corresponds to a different painting in different temperature pixels. The prime voltage VP, in the portion where the image grayscale value is greater than the grayscale threshold, each image grayscale value corresponds to the same pixel voltage VP in pixels of different temperatures.

It should be noted that, in FIG. 1 , the light-emitting elements 121 and 123 are disposed on the upper and lower sides of the liquid crystal display panel 110 , so the temperature of the liquid crystal display panel 110 changes vertically, so that the dark state can be adjusted according to the vertical position of the target pixel. The pixel voltage VP corresponding to each image grayscale value CG in the portion. When the light-emitting elements 121 and 123 are disposed on the left and right sides of the liquid crystal display panel 110, the temperature of the liquid crystal display panel 110 changes horizontally. Therefore, the grayscale value of each image in the dark state portion can be adjusted according to the horizontal position of the target pixel. Corresponding pixel voltage VP. In other embodiments, the light emitting element may be disposed only on one side (upper, lower, left, or right) of the liquid crystal display panel 110, and the manner in which the pixel voltage VP is adjusted may be understood according to the above embodiment.

The above embodiment is applied to a liquid crystal panel that displays black in a normal state, except In addition, the present invention can also be applied to a normally black liquid crystal panel. Hereinafter, a vertical alignment (VA) type liquid crystal display panel will be described as an example. 4 is a characteristic diagram of a vertical alignment type liquid crystal according to an embodiment of the present invention. Referring to FIG. 1 and FIG. 4, in the vertical alignment type liquid crystal, the transmittance may increase as the temperature rises, but may decrease as the temperature rises, and the following description will be respectively made according to different conditions.

According to the above, it is assumed here that the curve 510 is a liquid crystal reaction curve at normal temperature, and the curve 520 is a liquid crystal reaction curve at a high temperature, wherein the curve 510 can correspond to the pixel columns L3 and L4, and the curve 520 can correspond to the pixel columns L1 and L6. . If the pixel voltage VP is adjusted by adjusting the color grayscale value CG, the comparison table according to the high temperature pixel columns L1 and L6 can refer to the comparison table 2, thereby adjusting each image in the pixel columns L1 and L6. The pixel voltage VP corresponding to the grayscale value. Further, the comparison table on which the pixel sequences L3 and L4 at normal temperature are based can be referred to the comparison table 1, thereby obtaining the pixel voltage VP corresponding to each image grayscale value in the pixel columns L3 and L4. If the pixel voltage VP is adjusted by adjusting the gamma voltage V _GM , the voltage range of the gamma voltage of the pixel columns L1 and L6 is the voltage range of V3 to 5 volts, and the voltage range of the gamma voltage of the pixel columns L3 and L4. It is 0~5 volts.

On the other hand, it is assumed that the curve 510 is a liquid crystal reaction curve at a high temperature, and the curve 520 is a liquid crystal reaction curve at a normal temperature, wherein the curve 510 may correspond to the pixel columns L1 and L6, and the curve 520 may correspond to the pixel columns L3 and L4. If the pixel voltage VP is adjusted by adjusting the color grayscale value CG, the comparison table according to the normal temperature pixel columns L3 and L4 can refer to the comparison table 2, thereby adjusting each image in the pixel columns L3 and L4. The pixel voltage VP corresponding to the grayscale value. Further, the comparison table on which the pixel columns L1 and L6 at a high temperature are based can refer to the comparison table 1 to obtain the pixel voltage VP corresponding to each image grayscale value in the pixel columns L1 and L6. If the pixel voltage VP is adjusted by adjusting the gamma voltage V _GM , the voltage range of the gamma voltage of the pixel columns L1 and L6 is 0 to 5 volts, and the voltage range of the gamma voltage of the pixel columns L3 and L4 is Voltage V3~5 volts.

According to the above, a driving method suitable for the liquid crystal display device 100 can be integrated. FIG. 5 is a flow chart of a driving method according to an embodiment of the present invention. Referring to FIG. 5, the screen data is first received (step S610), and the image grayscale value corresponding to the target pixel is obtained according to the screen data (step S620), wherein the target pixel is a plurality of liquid crystal display panels 110 of the liquid crystal display device 100. One of the pixels. Next, the pixel voltage VP corresponding to each image grayscale value is determined according to the current temperature of the target pixel (step S630). Finally, the pixel voltage corresponding to the image grayscale value is written to the target pixel (step S640). For details of the steps, reference may be made to the description of the above embodiments, and details are not described herein again.

In summary, the driving method of the present invention determines the degree of liquid crystal temperature rise and the degree of change of characteristics in the pixel according to the distance between the pixel and the light-emitting element, and then adjusts the pixel according to the degree of change of the characteristic change of the liquid crystal due to temperature. The pixel voltage corresponding to the grayscale value of each image in the dark state picture. Thereby, the pixel voltage corresponding to each image grayscale value in different temperature pixels can be adjusted, so that the liquid crystal display panel does not have obvious brightness difference when displaying the dark state image, thereby improving the liquid crystal display panel. In-plane uniformity. and, If the corresponding pixel voltage is adjusted by adjusting the color grayscale value corresponding to the grayscale value of the image, the in-plane uniformity of the liquid crystal display panel can be improved while maintaining the contrast.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

100‧‧‧Liquid crystal display device

110‧‧‧LCD panel

120‧‧‧Backlight module

121, 123‧‧‧Lighting elements

130‧‧‧Sequence Controller

140‧‧‧gate driver

150‧‧‧Source Driver

160‧‧‧Gamma Voltage Generator

170‧‧‧ memory components

210, 220, 510, 520‧‧‧ curves

410‧‧‧Voltage generating unit

420‧‧ ‧pressure unit

CG‧‧‧Color grayscale value

CKV‧‧‧ vertical clock signal

CKH‧‧‧ horizontal clock signal

Vcom‧‧‧Common voltage

STV‧‧‧ start signal

V1, V2, V3‧‧‧ voltage

VS‧‧‧ video signal

VR1~VR12‧‧‧ gamma reference voltage

VP‧‧‧ pixel voltage

V _GM ‧‧ gamma voltage

P1~P6‧‧‧ pixels

L1~L6‧‧‧画素

S610~S650‧‧‧Steps

1 is a system diagram of a liquid crystal display device in accordance with an embodiment of the present invention.

2 is a characteristic diagram of a twisted nematic liquid crystal according to an embodiment of the present invention.

3 is a schematic diagram of a system in which a gamma voltage generator is coupled to a memory element in accordance with an embodiment of the invention.

4 is a characteristic diagram of a vertical alignment type liquid crystal according to an embodiment of the present invention.

FIG. 5 is a flow chart of a driving method according to an embodiment of the present invention.

S610~S640‧‧‧Steps

Claims (17)

A driving method is applicable to a liquid crystal display device, comprising: receiving a picture data; obtaining an image gray level value corresponding to a target pixel according to the picture data, wherein the target pixel is a liquid crystal display panel of the liquid crystal display device One of the plurality of pixels; when the current temperature of the target pixel is a first temperature, providing a plurality of first gamma voltages, and selecting one of the gamma voltages as the image gray scale a pixel voltage corresponding to the value; when the current temperature of the target pixel is a second temperature, providing a plurality of second gamma voltages, and selecting one of the second gamma voltages as the image grayscale value Corresponding pixel voltage; when the current temperature of the target pixel is a third temperature, providing a plurality of third gamma voltages, and selecting one of the gamma voltages as the corresponding grayscale value of the image a voltage, wherein the third gamma voltage is obtained by performing an interpolation operation according to the first gamma voltage and the second gamma voltage; and writing a pixel voltage corresponding to the grayscale value of the image The head Pixel. The driving method of claim 1, wherein the current temperature of the target pixel is determined by a shortest distance between the target pixel and a light-emitting element of a backlight module of the liquid crystal display device. The driving method of claim 1, wherein when the grayscale value of the image is less than or equal to a grayscale threshold, the grayscale value of the image corresponds to different pixel voltages in the target pixel at different current temperatures. When the shadow When the grayscale value is greater than the grayscale threshold, the grayscale value of the image corresponds to the same pixel voltage in the target pixel of different current temperatures. The driving method of claim 1, wherein the providing the first gamma voltage comprises: obtaining a plurality of first gamma reference voltages corresponding to the first temperature; and according to the first gamma The reference voltage is divided to generate the first gamma voltages. The driving method of claim 4, wherein the providing the second gamma voltage comprises: obtaining a plurality of second gamma reference voltages corresponding to the second temperature; and according to the second gamma The reference voltage is divided to generate the second gamma voltages. The driving method of claim 5, wherein the portions of the first gamma reference voltages are different from the portions of the second gamma reference voltages corresponding to the same image grayscale value. The driving method of claim 6, wherein the image grayscale value corresponding to the portion between the first gamma reference voltage and the second gamma reference voltage is less than or equal to a grayscale threshold. The driving method of claim 1, wherein the liquid crystal display panel is normally white. The driving method of claim 1, wherein the liquid crystal display panel is normally black. The driving method of claim 1, wherein the liquid crystal display panel is a twisted nematic (TN) type liquid Crystal display panel. The driving method of claim 1, wherein the liquid crystal display panel is a vertical alignment (VA) type liquid crystal display panel. A driving method is applicable to a liquid crystal display device, comprising: receiving a picture data; obtaining an image gray level value corresponding to a target pixel according to the picture data, wherein the target pixel is a liquid crystal display panel of the liquid crystal display device One of the plurality of pixels; when the current temperature of the target pixel is a first temperature, providing a plurality of first gamma voltages, and selecting one of the gamma voltages as the image gray scale a pixel voltage corresponding to the value; when the current temperature of the target pixel is a second temperature, providing a plurality of second gamma voltages, and selecting one of the second gamma voltages as the image grayscale value Corresponding pixel voltage; and writing a pixel voltage corresponding to the grayscale value of the image to the target pixel; wherein, when the grayscale value of the image is less than or equal to a grayscale threshold, corresponding to the grayscale value of the image The first gamma voltage is different from the second gamma voltage corresponding to the grayscale value of the image. When the grayscale value of the image is greater than the grayscale threshold, the first gamma voltage corresponding to the grayscale value of the image is the same as the pair Should image The second gamma voltage level values. The driving method of claim 12, wherein the current temperature of the target pixel is determined by a shortest distance between the target pixel and a light-emitting element of a backlight module of the liquid crystal display device. The driving method of claim 1, wherein the liquid crystal display panel is normally white. The driving method of claim 1, wherein the liquid crystal display panel is normally black. The driving method of claim 1, wherein the liquid crystal display panel is a twisted nematic (TN) type liquid crystal display panel. The driving method of claim 1, wherein the liquid crystal display panel is a vertical alignment (VA) type liquid crystal display panel.