Display device and backlight compensation method thereof

Abstract

The invention discloses a backlight compensation method for enhancing area contrast, which is applied to a display device. The display device has a backlight module having a plurality of light emitting units. The light-emitting units are divided into a plurality of groups, and each group forms a light-emitting area. The backlight compensation method comprises the following steps: the backlight module executes an area dimming program according to a gamma value of the display device; obtaining a brightness peak value of each light-emitting area; selecting one of the light-emitting areas as a selected area; obtaining an area average brightness value according to the brightness peak values of the selected area and other light-emitting areas adjacent to the selected area; obtaining a brightness adjustment ratio according to a partial peak ratio corresponding to the regional average brightness value; obtaining a compensation brightness value according to the brightness peak value and the brightness adjustment ratio; and adjusting the brightness of the selected area according to the compensation brightness value.

Description

Technical Field

[0001] The present invention relates to a display device and a backlight control method thereof, and in particular to a display device and a backlight compensation method thereof. Background Art

[0002] Sub-millimeter light-emitting diode (Mini-LED) display technology has been widely used in various display devices, mainly because it can provide higher brightness, contrast and better color accuracy. In a backlight module with Mini-LED as the light-emitting unit, these light-emitting units are usually divided into multiple areas, each of which can be dimmed independently to improve display performance. However, the dimming algorithm of the existing Mini-LED local dimming technology is mainly aimed at energy saving, which will lead to a decrease in display performance under certain conditions, especially at different window opening rates and grayscale values, which will cause problems with optical characteristics.

[0003] Specifically, the existing regional dimming technology will have problems with low brightness and gamma values ​​when dealing with different window opening rates. The window opening rate refers to the proportion of bright areas in the display image. Different window opening rates will cause changes in the energy distribution of the light-emitting unit. When the window opening rate is low, the existing dimming algorithm may not be able to provide sufficient brightness compensation, resulting in poor display effects. Similarly, at different grayscale levels, the existing dimming technology cannot effectively maintain the stability of the gamma curve, resulting in a decrease in image contrast and layering.

[0004] In addition, AmLED technology, as an improved regional dimming technology, improves brightness at different window opening rates and grayscales by expanding light compensation or directly improving grayscale compensation. However, this method may still lead to an intensification of the halo effect and a reduction in data resolution, which in turn affects the accuracy and display quality of the image. The halo effect refers to the halo phenomenon that appears around high-brightness areas, which blurs the edges of the image and affects the visual experience. In addition, although directly improving grayscale compensation can increase brightness, it will also reduce the detail performance and accuracy of the image.

[0005] Although Mini-LED and AmLED technologies offer significant advantages in many aspects, in practical applications, there are still problems such as unstable optical properties, halo effect, and grayscale compensation. Therefore, effectively solving the above problems will contribute to the further development and application of sub-millimeter light-emitting diode technology, which is one of the current important topics. Summary of the invention

[0006] The present invention provides a display device and a backlight compensation method for enhancing regional contrast, so as to improve the optical quality of the display device and further solve the unstable optical characteristics and halo effect caused by regional dimming.

[0007] To achieve the above-mentioned purpose, the present invention provides a backlight compensation method for enhancing regional contrast, which is applied to a display device. The display device has a backlight module, and the backlight module has a plurality of light-emitting units arranged in an array. The light-emitting units are divided into a plurality of groups, and each group constitutes a light-emitting area. The backlight compensation method includes the following steps: the backlight module performs a regional dimming program according to the gamma value of the display device; obtains the brightness peak of each light-emitting area; selects one of the light-emitting areas as the selected area; obtains the regional average brightness value according to the brightness peak of the selected area and other light-emitting areas adjacent to the selected area; obtains the brightness adjustment ratio according to the ratio of a portion of the peak values ​​corresponding to the regional average brightness value; obtains the compensation brightness value according to the brightness peak and the brightness adjustment ratio; and adjusts the brightness of the selected area according to the compensation brightness value.

[0008] In one embodiment of the present invention, the above-mentioned partial peak ratios are stored in a partial peak ratio comparison table.

[0009] In one embodiment of the present invention, the compensation brightness value is the product of the brightness peak value and the brightness adjustment ratio.

[0010] In one embodiment of the present invention, the above-mentioned partial peak ratio ranges from 1% to 100%.

[0011] In one embodiment of the present invention, the above-mentioned partial peak ratio (PPR) is calibrated by interpolation of detail nodes through multiple sets of partial peak ratio comparison tables.

[0012] In addition, to achieve the above-mentioned purpose, the present invention provides a display device, including a backlight module, a display module and a driving module. The backlight module has a plurality of light-emitting units arranged in an array. The light-emitting units are divided into a plurality of groups, each group constituting a light-emitting area, wherein the light-emitting area has a brightness peak. In addition, a light-emitting area is selected as a selected area, and there is a regional average brightness value between the brightness peaks of the selected area and its adjacent light-emitting areas. The display module is used to display images. The driving module is coupled to the backlight module and the display module, and the driving module performs a regional dimming program on the backlight module according to a gamma value, and drives the brightness of the selected area to a compensation brightness value according to the brightness peak and a brightness adjustment ratio, wherein the brightness adjustment ratio is obtained according to the partial peak ratio corresponding to the regional average brightness value, and the compensation brightness value is obtained according to the brightness peak and the brightness adjustment ratio.

[0013] In one embodiment of the present invention, the light emitting unit comprises a primary light emitting diode.

[0014] In one embodiment of the present invention, the driving module performs a local dimming procedure based on a gamma value of 2.2 of the display device.

[0015] As described above, the display device and the backlight compensation method for enhancing regional contrast of the present invention adjust the average brightness of each luminous area by taking the average brightness of the luminous areas adjacent to each luminous area into consideration in the adjustment strategy, thereby improving the stability of the optical characteristics of the display device and improving the halo effect.

[0016] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following specifically cites a preferred embodiment and describes it in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of a display device according to a preferred embodiment of the present invention;

[0018] Figure 2 A schematic diagram of the layout of the light-emitting units of the backlight module of the present invention;

[0019] Figure 3 is a schematic diagram of the light emitting area of ​​the backlight module of the present invention;

[0020] Figure 4 is a flow chart of a backlight compensation method according to a preferred embodiment of the present invention;

[0021] Figure 5A is a schematic diagram of the light-emitting area of ​​the backlight module and the corresponding peak brightness value;

[0022] Figure 5B is a schematic diagram of a partial peak ratio comparison table; and

[0023] Figure 5C is a schematic diagram of the light-emitting area of ​​the backlight module and the corresponding compensation brightness value. DETAILED DESCRIPTION

[0024] See also Figure 1 As shown, a display device 10 of a preferred embodiment of the present invention includes a backlight module 11, a display module 12 and a driving module 13. In this embodiment, the driving module 13 can drive the backlight module 11 and the display module 12 respectively, so that the light L01 emitted by the backlight module 11 passes through the display module 12 and then displays an image on a display panel 121.

[0025] The backlight module 11 is a direct-type backlight module. Figure 2As shown, the backlight module 11 has a plurality of light-emitting units 111 arranged in an array, such as but not limited to light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), sub-millimeter light-emitting diodes (Mini-LEDs) or micro-light-emitting diodes (Micro-LEDs). This embodiment takes Mini-LEDs as an example. The so-called array arrangement refers to the arrangement and combination of light-emitting units 111 in rows and columns, and is not limited to aligned arrangement or staggered arrangement. Figure 2 and Figure 3 As shown, the array-arranged light-emitting units 111 are divided into a plurality of groups, each of which constitutes a light-emitting area. This embodiment takes nine light-emitting areas A01 to A09 as an example, but is not limited thereto. It may also be divided into, for example, 512 light-emitting areas or 1024 areas. Furthermore, each light-emitting area may include only one light-emitting unit.

[0026] Back to Figure 1 The driving module 13 is coupled to the backlight module 11 and the display module 12 to control the dimming and compensation process of the light emitting unit 111 of the backlight module 11 .

[0027] Next, please also refer to Figures 1 to 4 As shown, a backlight compensation method for enhancing regional contrast according to a preferred embodiment of the present invention is described. Figure 4 The flowchart of the backlight compensation method of the preferred embodiment of the present invention is shown. The backlight compensation method includes steps S01 to S06.

[0028] Step S01 is that the backlight module 11 executes a regional dimming program according to the gamma value (e.g., gamma 2.2) of the display device 10. In the present embodiment, the regional dimming program includes the backlight module 11 independently adjusting the luminous brightness of each light-emitting unit 111 according to the brightness of each part of the display screen. In this way, the brightness of the corresponding light-emitting unit 111 can be reduced when displaying a dark image to increase the depth of black, and the brightness of the corresponding light-emitting unit 111 can be increased when displaying a bright image to enhance the brightness of the image. The above-mentioned regional dimming program can apply AmLED technology, using an active matrix drive circuit to control the switch of each sub-millimeter light-emitting diode, or to perform precise brightness control on each area. In other words, the present embodiment compensates for gamma when executing the regional dimming program, and maintains the gamma value at 2.2 by adjusting the backlight brightness under different display areas.

[0029] Step S02 is to obtain the peak brightness (Area Peak Luminance, APL) of each light-emitting area A01-A09. In the backlight module 11 of the display device 10, the peak brightness of each light-emitting area A01-A09 can be obtained by a light detection element, such as a photodiode. The number of light detection elements can be one or more, and is not limited here.

[0030] Step S03 is to select a light-emitting area as a selected area. The selected area can be selected in sequence or randomly, which is not limited here. Here, the light-emitting area A01 is selected as the selected area for example.

[0031] Step S04 is to obtain a regional average brightness value based on the brightness peaks of the selected region and its adjacent light-emitting regions. Figure 3 As shown, the selected area in this embodiment is the light-emitting area A01, so its adjacent light-emitting areas include the light-emitting areas A02, A04 and A05, and then the regional average brightness value is obtained according to the brightness peak values ​​of the light-emitting areas A01, A02, A04 and A05. In this embodiment, the regional average brightness value can be obtained by adding the brightness peak values ​​of the light-emitting areas A01, A02, A04 and A05 and then dividing by 4.

[0032] Step S05 is to determine the brightness adjustment ratio according to the partial peak ratio (PPR) corresponding to the average brightness value of the region. The partial peak ratio ranges from 1% to 100% of a positive number, which can be stored in a partial peak ratio comparison table, and the partial peak ratio comparison table can be generated by real-time calculation, laboratory simulation or testing, which is not limited here. It is worth mentioning that the partial peak ratio can also be calibrated for detailed node interpolation through multiple sets of partial peak ratio comparison tables.

[0033] Step S06 is to obtain a compensation brightness value. The compensation brightness value is obtained according to the brightness peak value and the brightness adjustment ratio. In this embodiment, the compensation brightness value is the product of the brightness peak value and the brightness adjustment ratio.

[0034] Step S07 is to adjust the brightness of the selected area. In this embodiment, the brightness of the selected area A01 is adjusted according to the compensation brightness value. Steps S03 to S07 can be repeated until all luminous areas are adjusted according to the corresponding compensation brightness values, and the backlight compensation corresponding to the display screen is terminated.

[0035] See also FIG. 5A to FIG. 5CThe backlight compensation method of the present invention is described below by way of example. In the display device implementing the present invention, the backlight module 21 uses mini LED as a light-emitting unit and is divided into nine light-emitting areas A11 to A19. When the display device displays a specific image, regional dimming is performed according to the gamma value of the display device (e.g., gamma 2.2).

[0036] First, the peak brightness of each light emitting area A11 to A19 is obtained. In this embodiment, the peak brightness is expressed as a percentage, for example Figure 5A As shown, the peak brightness of the luminous area A11 is APL 10%, the peak brightness of the luminous area A12 is APL 70%, the peak brightness of the luminous area A13 is APL 30%, the peak brightness of the luminous area A14 is APL 50%, the peak brightness of the luminous area A15 is APL 50%, the peak brightness of the luminous area A16 is APL 70%, the peak brightness of the luminous area A17 is APL 70%, the peak brightness of the luminous area A18 is APL 30%, and the peak brightness of the luminous area A19 is APL 70%.

[0037] Next, the luminous area A11 is selected as the first selected area, and the regional average brightness values ​​of the adjacent luminous areas A11, A12, A14 and A15 are calculated based on the brightness peak values ​​of the selected area (luminous area A11) and its adjacent luminous areas A12, A14 and A15, that is, (10%+70%+50%+50%) / 4=45%. It is worth mentioning that in this embodiment, the brightness peak value or regional average brightness value is expressed in percentage, but in other embodiments, nits or cd / m 2 )express.

[0038] Next, see Figure 5B In the partial peak ratio comparison table T11, the corresponding brightness adjustment ratio is 77% according to the regional average brightness value of 45%. In this embodiment, the partial peak ratio comparison table T11 only lists the brightness adjustment ratios corresponding to the regional average brightness values ​​of 30% and 50% as 85% and 75%, respectively. Through appropriate calculation, the brightness adjustment ratio corresponding to the regional average brightness value of 45% is 77%. Then, as Figure 5C As shown, the peak brightness value (10%) of the selected area (luminous area A11) is multiplied by the brightness adjustment ratio 77%, and the compensated brightness value is 7.7%.

[0039] See also Figure 5A, then select the luminous area A12 as the second selected area, and calculate the regional average brightness value of these adjacent luminous areas A11, A12, A13, A14, A15 and A16 according to the brightness peak values ​​of the selected area (luminous area A12) and its adjacent luminous areas A11, A13, A14, A15 and A16, that is, (10% + 70% + 30% + 50% + 50% + 70%) / 6 = 46.67%.

[0040] Next, see Figure 5B In the partial peak ratio comparison table T11, the corresponding brightness adjustment ratio is 82% according to the regional average brightness value of 46.67%. In this embodiment, the partial peak ratio comparison table T11 only lists the brightness adjustment ratios of 85% and 75% corresponding to the regional average brightness values ​​of 30% and 50%, respectively. Through appropriate calculation, it can be obtained that the brightness adjustment ratio corresponding to the regional average brightness value of 46.67% is 82%. Then, as Figure 5C As shown, the peak brightness value (70%) of the selected area (luminous area A12) is multiplied by the brightness adjustment ratio 82% to obtain a compensated brightness value of 57.4%, and the brightness of the selected area (luminous area A12) is adjusted accordingly.

[0041] Then continue to perform the above steps for the luminous areas A13 to A19 to obtain the compensation brightness value corresponding to each luminous area, so as to correct the regional brightness of the backlight and enhance the regional contrast. It is worth noting that in this example, the backlight compensation is performed in the order of the luminous areas A11 to A19. In other examples, if the software and hardware can cooperate, the backlight compensation can also be performed in the order of A11, A14, A17, A12, A15, A18, A13, A16, and A19. Of course, in other embodiments, the order of performing backlight compensation can also be randomly selected.

[0042] Through the above description, the display device and backlight compensation method of the present invention can effectively compensate brightness at different window opening rates and grayscale levels to enhance regional contrast, reduce halo effect, and maintain the gamma value of the display device stable and high brightness, thereby improving display quality.

[0043] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes by using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A backlight compensation method is applied to a display device, which has a backlight module, and the backlight module has a plurality of light-emitting units arranged in an array, the light-emitting units are divided into a plurality of groups, each of the groups constitutes a light-emitting area, characterized in that: The method comprises the following steps: The backlight module performs a regional dimming process according to a gamma value of the display device; Obtaining a brightness peak value of each of the light-emitting areas; Selecting one of the light-emitting areas as a selected area; Obtaining an average brightness value of a region according to the brightness peaks of the selected region and the adjacent luminous regions; Obtaining a brightness adjustment ratio according to a portion of peak ratios corresponding to the average brightness value of the region; Obtaining a compensated brightness value according to the brightness peak value and the brightness adjustment ratio; and The brightness of the selected area is adjusted according to the compensated brightness value.

2. The backlight compensation method according to claim 1, wherein: The partial peak ratios are stored in a partial peak ratio comparison table.

3. The backlight compensation method according to claim 1, wherein: The compensation brightness value is the product of the brightness peak value and the brightness adjustment ratio.

4. The backlight compensation method according to claim 1, wherein: The partial peak ratio ranges from 1% to 100%.

5. The backlight compensation method according to claim 1, wherein: The partial peak ratio is calibrated by interpolation of detailed nodes through multiple groups of partial peak ratio comparison tables.

6. A display device, characterized in that: include: A backlight module, comprising a plurality of light-emitting units arranged in an array, wherein the light-emitting units are divided into a plurality of groups, each group forming a light-emitting area, and the light-emitting area having a brightness peak, wherein one of the light-emitting areas is selected as a selected area, and there is a regional average brightness value between the brightness peaks of the selected area and its adjacent light-emitting areas; A display module, used for displaying images; as well as A driving module is coupled to the backlight module and the display module, and the driving module performs a regional dimming procedure on the backlight module according to a gamma value, and drives the brightness of the selected area to a compensated brightness value according to the brightness peak value and a brightness adjustment ratio, wherein the brightness adjustment ratio is obtained according to a partial peak ratio corresponding to an average brightness value of the area, and the compensated brightness value is obtained according to the brightness peak value and the brightness adjustment ratio.

7. The display device according to claim 6, wherein: The light emitting unit includes a primary millimeter light emitting diode.

8. The display device according to claim 6, wherein: The driving module executes the local dimming procedure based on a gamma value of 2.2 of the display device.

9. The display device according to claim 6, wherein: The brightness adjustment ratio ranges from 1% to 100%.

10. The display device according to claim 6, wherein: The driving module performs detailed node interpolation calibration through multiple groups of partial peak ratio comparison tables.

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