Gamma value calculation method for display panel

Abstract

A gamma value calculation method for a display panel is disclosed. The gamma value calculation method for the display panel includes the following steps: measuring a first luminance value of at least one first color pixel included in the j-th display area at a first object gray level; measuring a second luminance value of at least one second color pixel included in the j-th display area at the first object gray level; deriving a predicted drive current flowing through the second color pixel at the first object gray level based on the gray level-drive current correspondence of the second color; deriving a second object gray level when the predicted drive current flows through the first color pixel based on the gray level-drive current correspondence of the first color; and calculating an object gamma value to be applied to the first color pixels included in the j-th display area based on the first object gray level, the second object gray level, the first luminance value, and the second luminance value.

Description

Technical Field

[0001] The present invention relates to an organic light emitting display device. More particularly, the present invention relates to a gamma value calculation method for calculating a plurality of RGB-based gamma values to be applied to a plurality of display regions of a display panel included in an organic light emitting display device. Background Art

[0002] Recently, organic light emitting display devices have been widely used as display devices equipped in electronic devices. Generally, due to various reasons in the manufacturing process, there are characteristic deviations between pixels included in the display panel of the organic light emitting display device. Accordingly, there may also be characteristic deviations between identically manufactured display panels. That is, even when the same data is applied to identically manufactured display panels, the color coordinates and / or brightness of the images displayed on the display panels may be different. For this reason, when manufacturing an organic light emitting display device, the following process may be performed: after a test image is displayed on the display panel, the brightness value achieved by the display region (or pixel) of the display panel is measured by a brightness measurement device, a compensation parameter according to the display region is generated by analyzing the brightness value, and the compensation parameter according to the display region is stored in a predetermined memory device in the organic light emitting display device. Accordingly, the organic light emitting display device can perform brightness compensation for compensating input image data based on the compensation parameter according to the display region to generate output image data. However, there is a problem that when generating the compensation parameter according to the display region, if the same RGB-based gamma value is applied to all display regions of the display panel, the brightness deviation according to the display region is not large in a high gray scale image, but the brightness deviation according to the display region is large in a low gray scale image. Therefore, although the RGB-based gamma values are set differently for each display region of the display panel (for example, the RGB-based gamma values to be assigned to low gray scales are set differently for each display region of the display panel, and the RGB-based gamma values to be assigned to high gray scales are set identically for all display regions of the display panel), in order to set the RGB-based gamma values differently for each display region of the display panel, at least two test images having different gray scales from each other need to be captured for each color (i.e., RGB), and thus there is a limitation in extending the manufacturing process of the organic light emitting display device. Summary of the Invention

[0003] An object of the present invention is to provide a method for calculating gamma values for a display panel, that is, when gamma values according to RGB are differently set for each display area of a display panel included in an organic light-emitting display device, even if only one test image is captured for each color (i.e., RGB), first gamma values according to RGB to k-th gamma values according to RGB that will be respectively applied to a first display area to a k-th display area of the display panel can be calculated. However, the object of the present invention is not limited to the above object and can be extended in various ways without departing from the spirit and concept of the present invention.

[0004] To achieve an object of the present invention, a method for calculating gamma values for a display panel according to an embodiment of the present invention can calculate first gamma values according to RGB to k-th gamma values according to RGB that will be respectively applied to a first display area to a k-th display area, where k is an integer greater than or equal to 2. Specifically, the gamma value calculation method may include the following steps: measuring a first luminance value of at least one first color pixel included in a j-th display area at a first target gray level, where j is an integer greater than or equal to 1 and less than or equal to k; measuring a second luminance value of at least one second color pixel included in the j-th display area at the first target gray level; deriving a predicted drive current flowing through the second color pixel at the first target gray level based on a gray level-drive current correspondence relationship of the second color; deriving a second target gray level when the predicted drive current flows through the first color pixel based on a gray level-drive current correspondence relationship of the first color; and calculating an object gamma value to be applied to the first color pixel included in the j-th display area based on the first target gray level, the second target gray level, the first luminance value, and the second luminance value.

[0005] According to an embodiment, the gray level-drive current correspondence relationships of the first color and the second color can be determined in advance at the design stage of the display panel according to the characteristics of drive transistors and organic light-emitting diodes designed to be included in the first color pixel and the second color pixel.

[0006] According to an embodiment, the first color pixel may be one of a red pixel, a green pixel, and a blue pixel, and the second color pixel is a pixel of a color different from the first color pixel among a red pixel, a green pixel, and a blue pixel.

[0007] According to an embodiment, the gray level-drive current correspondence relationships of the first color and the second color may be gray level-drive current curves of the first color and the second color, respectively.

[0008] According to an embodiment, the step of measuring a first luminance value of at least one first-color pixel included in the j-th display region at a first object gray level may include: after displaying a first-color test image having the first object gray level on the display panel, measuring the first luminance value achieved by at least one first-color pixel included in the j-th display region through a luminance measuring device, wherein the step of measuring a second luminance value of at least one second-color pixel included in the j-th display region at the first object gray level includes: after displaying a second-color test image having the first object gray level on the display panel, measuring the second luminance value achieved by at least one second-color pixel included in the j-th display region through the luminance measuring device.

[0009] According to an embodiment, the gamma value calculation method may further include the following steps: assigning the object gamma value to an object gray level region to which the first object gray level belongs among all the gray levels achieved by the first-color pixels; and assigning a reference gamma value of the display panel to a non-object gray level region to which the first object gray level does not belong among all the gray levels achieved by the first-color pixels.

[0010] According to an embodiment, the reference gamma value may be 2.2.

[0011] According to an embodiment, the object gray level region may be a low gray level region that is less than or equal to the first object gray level among all the gray levels achieved by the first-color pixels.

[0012] According to an embodiment, the first luminance value may be an arithmetic mean luminance value of the first-color pixels included in the j-th display region, and the second luminance value may be an arithmetic mean luminance value of the second-color pixels included in the j-th display region.

[0013] According to an embodiment, the first luminance value may be a weighted mean luminance value of the first-color pixels included in the j-th display region, and the second luminance value may be a weighted mean luminance value of the second-color pixels included in the j-th display region.

[0014] According to an embodiment, the first luminance value may be a luminance value of one pixel among the first-color pixels included in the j-th display region, and the second luminance value may be a luminance value of one pixel among the second-color pixels included in the j-th display region.

[0015] According to an embodiment, the j-th display region may be constituted by one unit pixel including at least one red pixel, at least one green pixel, and at least one blue pixel.

[0016] According to an embodiment, the j-th display area may be constituted by a plurality of unit pixels respectively including at least one red pixel, at least one green pixel, and at least one blue pixel.

[0017] According to an embodiment, the object gamma value may be calculated independently of a reference display area gamma value set for a reference display area.

[0018] According to an embodiment, the object gamma value may be calculated by Equation 1:

[0019] [Equation 1]

[0020]

[0021] (Wherein, TGV is the object gamma value, FLV is the first luminance value, SLV is the second luminance value, FTG is the first object gray level, and STG is the second object gray level.)

[0022] According to an embodiment, the object gamma value may be calculated by reflecting a reference display area gamma value set for a reference display area.

[0023] According to an embodiment, the object gamma value may be calculated by Equation 2:

[0024] [Equation 2]

[0025]

[0026] (Wherein, TGV is the object gamma value, FLV is the first luminance value, SLV is the second luminance value, FTG is the first object gray level, STG is the second object gray level, and C is a constant for reflecting the reference display area gamma value.)

[0027] According to an embodiment, the reference display area may be a central display area of the display panel among the first display area to the k-th display area.

[0028] According to an embodiment, the reference display area gamma value may be a reference gamma value of the display panel.

[0029] According to an embodiment, the reference display area gamma value may be 2.2.

[0030] To achieve an object of the present invention, a gamma value calculation method for a display panel according to an embodiment of the present invention may include the following steps: obtaining first brightness values, second brightness values, and third brightness values respectively achieved by first color pixels, second color pixels, and third color pixels constituting a first display area included in the display panel at a first target gray level; predicting a second target gray level corresponding to when the first color pixels achieve the second brightness value by using the second brightness value achieved by the second color pixels at the first target gray level based on the gray level-driving current correspondence relationship between the first color and the second color; predicting a third target gray level corresponding to when the second color pixels achieve the third brightness value by using the third brightness value achieved by the third color pixels at the first target gray level based on the gray level-driving current curves of the second color and the third color; predicting a fourth target gray level corresponding to when the third color pixels achieve the first brightness value by using the first brightness value achieved by the first color pixels at the first target gray level based on the gray level-driving current curves of the third color and the first color; determining a first target gamma value to be applied to the first color pixels of the first display area based on the first brightness value, the second brightness value, the first target gray level, and the second target gray level; determining a second target gamma value to be applied to the second color pixels of the first display area based on the second brightness value, the third brightness value, the first target gray level, and the third target gray level; and determining a third target gamma value to be applied to the third color pixels of the first display area based on the third brightness value, the first brightness value, the first target gray level, and the fourth target gray level.

[0031] A method for calculating gamma values for a display panel according to an embodiment of the present invention is as follows: When calculating the first RGB-based gamma value to the k-th (where k is an integer greater than or equal to 2) RGB-based gamma value to be applied to the first display area to the k-th display area of the display panel, after displaying a first color test image with a first object gray level on the display panel, measuring a first luminance value achieved by at least one first color pixel included in the j-th (where j is an integer greater than or equal to 1 and less than or equal to k) display area by a luminance measuring device, after displaying a second color test image with the first object gray level on the display panel, measuring a second luminance value achieved by at least one second color pixel included in the j-th display area by the luminance measuring device, deriving a predicted drive current flowing through the second color pixel at the first object gray level based on the gray level-drive current curve according to RGB, deriving a second object gray level when the predicted drive current flows through the first color pixel based on the gray level-drive current curve according to RGB, and calculating an object gamma value to be applied to the first color pixels included in the j-th display area based on the first object gray level, the second object gray level, the first luminance value achieved by at least one first color pixel included in the j-th display area at the first object gray level, and the second luminance value achieved by at least one second color pixel included in the j-th display area at the first object gray level. Thus, even if only one test image is captured for each color (i.e., RGB), the first RGB-based gamma value to the k-th RGB-based gamma value to be applied to the first display area to the k-th display area of the display panel can be calculated using the gray level-drive current curve according to RGB. Accordingly, the gamma value calculation method can solve the problem in the prior art that the manufacturing process of the organic light-emitting display device is prolonged in order to differently set the RGB-based gamma values for each display area of the display panel. Therefore, it can be easily applied to the mass production of organic light-emitting display devices. However, the effects of the present invention are not limited to the above effects and can be extended in various ways without departing from the spirit and concept of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 FIG. is a flowchart showing a method for calculating gamma values for a display panel according to an embodiment of the present invention.

[0033] Figure 2 FIG. shows an example of a display panel to which Figure 1 the gamma value calculation method is applied.

[0034] Figure 3 FIG. shows an example of a unit pixel included in a display panel to which Figure 1 the gamma value calculation method is applied.

[0035] Figure 4 FIG. shows for Figure 1A diagram showing an example of a grayscale-driving current curve according to RGB for a gamma value calculation method.

[0036] Figure 5 It shows an example of a flowchart for assigning gamma values to an object grayscale region and a non-object grayscale region by the Figure 1 gamma value calculation method.

[0037] Figure 6 A diagram for explaining an example of assigning gamma values to an object grayscale region and a non-object grayscale region by the Figure 1 gamma value calculation method.

[0038] Figure 7 A block diagram showing an organic light-emitting display device according to an embodiment of the present invention.

[0039] Figure 8 A diagram for explaining Figure 7 the brightness compensation performed by the organic light-emitting display device.

[0040] Figure 9 A block diagram showing an electronic device according to an embodiment of the present invention.

[0041] Figure 10 A diagram showing an example of Figure 9 the electronic device being implemented as a smart phone.

[0042]

Explanation of Reference Numerals

[0043] 100: Display panel DP: Display area

[0044] 111: Unit pixel 111R: Red pixel

[0045] 111G: Green pixel 111B: Blue pixel

[0046] RCV: Red grayscale-driving current curve GCV: Green grayscale-driving current curve

[0047] BCV: Blue grayscale-driving current curve FTG: First object grayscale

[0048] STG: Second object grayscale EDC: Predicted driving current

[0049] MIG: Minimum grayscale MXG: Maximum grayscale

[0050] TGR: Object grayscale region NTGR: Non-object grayscale region

[0051] 500: Organic light-emitting display device 510: Display panel

[0052] 520: Scan driver 530: Data driver

[0053] 540: Timing controller 550: Memory device

[0054] DATA: Input image data C-PAR: Compensation parameter according to display area

[0055] CDATA: Output image data 1000: Electronic device

[0056] 1010: Processor 1020: Memory device

[0057] 1030: Storage device 1040: Input / output device

[0058] 1050: Power supply 1060: Organic light-emitting display device Detailed implementation manner

[0059] Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. The same reference numerals are used for the same components in the drawings, and repeated descriptions of the same components are omitted.

[0060] Figure 1 is a flowchart showing a method for calculating a gamma value for a display panel according to an embodiment of the present invention, Figure 2 is a diagram showing an example of a display panel to which Figure 1 the applied gamma value calculation method is applied, Figure 3 is a diagram showing an example of a unit pixel included in a display panel to which Figure 1 the applied gamma value calculation method is applied, Figure 4 is a diagram showing an example of a gray-scale - drive current curve according to RGB for Figure 1 the gamma value calculation method to be used.

[0061] Referring to Figures 1 to 4 , Figure 1 the gamma value calculation method can calculate the first gamma value according to RGB to the k-th gamma value according to RGB that are respectively to be applied to the first display area DP1 to the k-th (where k is an integer of 2 or more) display areas DPk of the display panel 100. That is, Figure 1The gamma value calculation method can calculate the first RGB gamma values (i.e., the first red gamma value, the first green gamma value, and the first blue gamma value) to be applied to the first display area DP1, calculate the second RGB gamma values (i.e., the second red gamma value, the second green gamma value, and the second blue gamma value) to be applied to the second display area DP2, calculate the (k - 1)th RGB gamma values (i.e., the (k - 1)th red gamma value, the (k - 1)th green gamma value, and the (k - 1)th blue gamma value) to be applied to the (k - 1)th display area DPk - 1, and calculate the kth RGB gamma values (i.e., the kth red gamma value, the kth green gamma value, and the kth blue gamma value) to be applied to the kth display area DPk. In addition, as Figure 2 shown, the display panel 100 includes the first display area DP1 to the kth display area DPk, Figure 1 and the gamma value calculation method is applied to all of the first display area DP1 to the kth display area DPk. However, for ease of explanation, in this specification, the gamma value calculation method will be described based on the jth display area DPj Figure 1 .

[0062] Specifically, Figure 1The gamma value calculation method may include the following steps: measuring a first luminance value achieved by at least one first color pixel included in the j-th (where j is an integer greater than or equal to 1 and less than or equal to k) display region DPj at a first object gray level (S110). For example, after displaying a first color test image with a first object gray level FTG on the display panel 100, measuring the first luminance value achieved by at least one first color pixel included in the j-th display region DPj through a luminance measuring device; measuring a second luminance value achieved by at least one second color pixel included in the j-th display region DPj at the first object gray level (S120). For example, after displaying a second color test image with a first object gray level FTG on the display panel 100, measuring the second luminance value achieved by at least one second color pixel included in the j-th display region DPj through a luminance measuring device. For example, the first color pixel may be a red pixel 111R, and the second color pixel may be a green pixel 111G or a blue pixel 111B. As another example, the first color pixel may be a green pixel 111G, and the second color pixel may be a red pixel 111R or a blue pixel 111B. As yet another example, the first color pixel may be a blue pixel 111B, and the second color pixel may be a red pixel 111R or a green pixel 111G. In one embodiment, the first luminance value achieved by at least one first color pixel included in the j-th display region DPj may be the arithmetic mean luminance value of at least one first color pixel included in the j-th display region DPj, and the second luminance value achieved by at least one second color pixel included in the j-th display region DPj may be the arithmetic mean luminance value of at least one second color pixel included in the j-th display region DPj. In another embodiment, the first luminance value achieved by at least one first color pixel included in the j-th display region DPj may be the weighted mean luminance value of at least one first color pixel included in the j-th display region DPj (for example, calculating the mean luminance value by assigning a larger weight value to the luminance value of a specific pixel and a smaller weight value to the luminance values of other specific pixels), and the second luminance value achieved by at least one second color pixel included in the j-th display region DPj may be the weighted mean luminance value of at least one second color pixel included in the j-th display region DPj. In yet another embodiment, the first luminance value achieved by at least one first color pixel included in the j-th display region DPj may be the luminance value of one first color pixel among at least one first color pixel included in the j-th display region DPj (for example, the luminance value of a representative pixel), and the second luminance value achieved by at least one second color pixel included in the j-th display region DPj may be the luminance value of one second color pixel among at least one second color pixel included in the j-th display region DPj.

[0063] Such as Figure 2As shown, the display panel 100 may include a first display area DP1 to a k-th display area DPk, and each of the first display area DP1 to the k-th display area DPk may include at least one unit pixel 111. In one embodiment, each of the first display area DP1 to the k-th display area DPk (i.e., the j-th display area DPj) may be constituted by one unit pixel 111 including at least one red pixel 111R, at least one green pixel 111G, and at least one blue pixel 111B. In another embodiment, each of the first display area DP1 to the k-th display area DPk (i.e., the j-th display area DPj) may be constituted by a plurality of unit pixels 111 respectively including at least one red pixel 111R, at least one green pixel 111G, and at least one blue pixel 111B. For example, as Figure 3 shown, the unit pixel 111 may have an RGB stripe structure. As another example, the unit pixel 111 may also have a Pentile structure. That is, since the red pixels 111R, green pixels 111G, and blue pixels 111B included in each of the first display area DP1 to the k-th display area DPk are arranged adjacent to each other, the operating characteristics of the transistors (e.g., driving transistors) constituting them may be similar. At this time, since in each pixel, the luminance characteristics according to the input voltage are similar when the driving current of the driving transistor in the corresponding pixel is the same, the luminance characteristics according to the input voltage of the red pixels 111R, green pixels 111G, and blue pixels 111B included in each of the first display area DP1 to the k-th display area DPk (i.e., adjacent to each other) may be similar. Therefore, Figure 1 the gamma value calculation method may calculate the first RGB-based gamma value to the k-th RGB-based gamma value to be respectively applied to the first display area DP1 to the k-th display area DPk by utilizing the similarity of the luminance characteristics according to the input voltage among the red pixels 111R, green pixels 111G, and blue pixels 111B included in each of the first display area DP1 to the k-th display area DPk.

[0064] Thereafter, Figure 1The gamma value calculation method can derive the predicted drive current EDC when the first target gray level FTG flows through the second color pixel based on the gray level-drive current correspondence relationship of RGB (gray level-drive current curves RCV, GCV, and BCV of RGB), and derive the second target gray level STG when the predicted drive current EDC flows through the first color pixel based on the gray level-drive current curves RCV, GCV, and BCV of RGB (S140). In addition, the gray level-drive current curves RCV, GCV, and BCV of RGB can be predetermined at the design stage of the display panel 100 according to the characteristics of the drive transistors and organic light-emitting diodes designed to be included in the first color pixel and the second color pixel. For example, Figure 4 shows a case where the first color pixel is the green pixel 111G, the second color pixel is the blue pixel 111B, and the first target gray level FTG is 11 gray levels, and the second target gray level STG of 23 gray levels is derived. Specifically, when the predicted drive current EDC when the first target gray level FTG of 11 gray levels flows through the blue pixel 111B is derived based on the blue gray level-drive current curve BCV, the second target gray level STG when the predicted drive current EDC flows through the green pixel can be derived as 23 gray levels based on the green gray level-drive current curve GCV. At this time, since the luminance characteristics according to the input voltage among the red pixel 111R, the green pixel 111G, and the blue pixel 111B included in the j-th display area DPj are similar to each other, the luminance value (i.e., the predicted luminance value) realized by at least one first color pixel included in the j-th display area DPj at the second target gray level STG can be substantially the same as the second luminance value (i.e., the measured luminance value) realized by at least one second color pixel included in the j-th display area DPj at the first target gray level FTG. As a result, Figure 1 the gamma value calculation method can grasp the first target gray level FTG, the second target gray level STG, the first luminance value realized by at least one first color pixel included in the j-th display area DPj at the first target gray level FTG, and the second luminance value realized by at least one second color pixel included in the j-th display area DPj at the first target gray level FTG (i.e., the luminance value realized by at least one first color pixel included in the j-th display area DPj at the second target gray level STG).

[0065] Next, Figure 1The gamma value calculation method can calculate the object gamma value to be applied to the first color pixels included in the j-th display area DPj based on the first object gray scale FTG, the second object gray scale STG, the first luminance value achieved by at least one first color pixel included in the j-th display area DPj at the first object gray scale FTG, and the second luminance value achieved by at least one second color pixel included in the j-th display area DPj at the first object gray scale FTG (S150). In an embodiment, the object gamma value to be applied to the first color pixels included in the j-th display area DPj can be calculated independently (or irrespectively) of the reference display area gamma value set for the reference display area. At this time, the reference display area can be the central display area of the display panel 100 among the first display area DP1 to the k-th display area DPk. For example, the reference display area gamma value set for the reference display area (e.g., the central display area) can be the reference gamma value of the display panel 100, and the reference gamma value of the display panel 100 can be 2.2. That is, the reference display area gamma value set for the reference display area (e.g., the central display area) can be 2.2. In this case, when calculating the object gamma value to be applied to the first color pixels included in the j-th display area DPj, the reference display area gamma value set for the reference display area (e.g., the central display area) can be not considered. Specifically, the object gamma value to be applied to the first color pixels included in the j-th display area DPj can be calculated by the following [Equation 1].

[0066] [Equation 1]

[0067]

[0068] (where TGV is the object gamma value to be applied to the first color pixels included in the j-th display area DPj, FLV is the first luminance value achieved by the first color pixels included in the j-th display area DPj at the first object gray scale FTG, SLV is the second luminance value achieved by the second color pixels included in the j-th display area DPj at the first object gray scale FTG, FTG is the first object gray scale, and STG is the second object gray scale.)

[0069] In another embodiment, an object gamma value to be applied to a first color pixel included in the j-th display region DPj may be calculated by reflecting a reference display region gamma value set for a reference display region. At this time, the reference display region may be a central display region of the display panel 110 among the first display region DP1 to the k-th display region DPk. For example, the reference display region gamma value set for the reference display region (e.g., the central display region) may be a reference gamma value of the display panel 100, and the reference gamma value of the display panel 100 may be 2.2. That is, the reference display region gamma value set for the reference display region (e.g., the central display region) may be 2.2. In this case, when calculating the object gamma value to be applied to the first color pixel included in the j-th display region DPj, the reference display region gamma value set for the reference display region (e.g., the central display region) may be considered. Specifically, the object gamma value to be applied to the first color pixel included in the j-th display region DPj may be calculated by the following [Equation 2]. For example, when the reference display region gamma value set for the reference display region (e.g., the central display region) is 2.2 (i.e., substituting 2.2 into TGV), since the first luminance value (i.e., FLV) of the first color pixel included in the j-th display region DPj at the first object gray level FTG, the second luminance value (i.e., SLV) of the second color pixel included in the j-th display region DPj at the first object gray level FTG, the first object gray level (i.e., FTG), and the second object gray level (i.e., STG) are already known, a constant C for reflecting the reference display region gamma value can be obtained. Therefore, when calculating the object gamma value to be applied to the first color pixel included in the j-th display region DPj using the following [Equation 2], the reference display region gamma value set for the reference display region (e.g., the central display region) can be reflected (i.e., a constant C for reflecting the reference display region gamma value may exist in the following [Equation 2]).

[0070] [Equation 2]

[0071]

[0072] (Where TGV is the object gamma value to be applied to the first color pixel included in the j-th display region DPj, FLV is the first luminance value of the first color pixel included in the j-th display region DPj at the first object gray level FTG, SLV is the second luminance value of the second color pixel included in the j-th display region DPj at the first object gray level FTG, FTG is the first object gray level, STG is the second object gray level, and C is a constant for reflecting the reference display region gamma value set for the reference display region.)

[0073] In addition, although it has been described that the first color pixels and the second color pixels included in the j-th display area DPj are divided, and the case where the object gamma value to be applied only to the first color pixels included in the j-th display area DPj is calculated, it is only for explaining the first luminance value achieved by the first color pixels included in the j-th display area DPj, the second luminance value achieved by the second color pixels included in the j-th display area DPj, and the case where the object gamma value to be applied to the first color pixels included in the j-th display area DPj is calculated according to the gray-scale driving current curves RCV, GCV, and BCV of RGB. It should be understood that Figure 1 the gamma value calculation method of Figure 1 calculates all the j-th RGB gamma values to be applied to the red pixel 111R, the green pixel 111G, and the blue pixel 111B included in the j-th display area DPj. In other words, Figure 1 the gamma value calculation method of Figure 1 is as follows: by using the first luminance value achieved by the red pixel 111R included in the j-th display area DPj at the first object gray scale FTG, the second luminance value achieved by the green pixel 111G or the blue pixel 111B included in the j-th display area DPj at the first object gray scale FTG, and the gray-scale driving current curve of RGB (i.e., deriving the second object gray scale STG) to calculate the object gamma value (i.e., the j-th red gamma value) to be applied to the red pixel 111R included in the j-th display area DPj; by using the first luminance value achieved by the green pixel 111G included in the j-th display area DPj at the first object gray scale FTG, the second luminance value achieved by the red pixel 111R or the blue pixel 111B included in the j-th display area DPj at the first object gray scale FTG, and the gray-scale driving current curve of RGB (i.e., deriving the second object gray scale STG) to calculate the object gamma value (i.e., the j-th green gamma value) to be applied to the green pixel 111G included in the j-th display area DPj; by using the first luminance value achieved by the blue pixel 111B included in the j-th display area DPj at the first object gray scale FTG, the second luminance value achieved by the red pixel 111R or the green pixel 111G included in the j-th display area DPj at the first object gray scale FTG, and the gray-scale driving current curve of RGB (i.e., deriving the second object gray scale STG) to calculate the object gamma value (i.e., the j-th blue gamma value) to be applied to the blue pixel 111B included in the j-th display area DPj.

[0074] In the prior art, in order to set the first RGB gamma value to the k-th RGB gamma value to be applied to the first display area DP1 to the k-th display area DPk, at least two test images with different grayscales are captured for each color (i.e., RGB) (for example, a red test image with a first target gray scale FTG and a red test image with a second target gray scale STG are captured, a green test image with a first target gray scale FTG and a green test image with a second target gray scale STG are captured, a blue test image with a first target gray scale FTG and a blue test image with a second target gray scale STG are captured). However, Figure 1 The gamma value calculation method can set the first RGB gamma value to the k-th RGB gamma value to be applied to the first display area DP1 to the k-th display area DPk by capturing only one test image with a predetermined gray scale (i.e., the first target gray scale FTG) for each color (i.e., RGB) by taking advantage of the similar luminance characteristics according to the input voltage among the red pixels 111R, green pixels 111G, and blue pixels 111B included in each of the first display area DP1 to the k-th display area DPk. For example, only a red test image with the first target gray scale FTG, a green test image with the first target gray scale FTG, and a blue test image with the first target gray scale FTG are captured. In this way, Figure 1The gamma value calculation method can calculate the first RGB-based gamma value to the k-th RGB-based gamma value to be applied to the first display area DP1 to the k-th display area DPk of the display panel 100. After displaying a first color test image with a first object gray level FTG on the display panel 100, the first luminance value achieved by at least one first color pixel included in the j-th display area DPj can be measured by a luminance measurement device. After displaying a second color test image with the first object gray level FTG on the display panel 100, the second luminance value achieved by at least one second color pixel included in the j-th display area DPj can be measured by the luminance measurement device. And based on the gray level-driving current curves RCV, GCV, BCV according to RGB, the predicted driving current EDC flowing through the second color pixel at the first object gray level FTG is derived. Based on the gray level-driving current curves RCV, GCV, BCV according to RGB, the second object gray level STG when the predicted driving current EDC flows through the first color pixel is derived. And based on the first object gray level FTG, the second object gray level STG, the first luminance value achieved by at least one first color pixel included in the j-th display area DPj at the first object gray level FTG, and the second luminance value achieved by at least one second color pixel included in the j-th display area DPj at the first object gray level FTG, the object gamma value to be applied to the first color pixels included in the j-th display area DPj is calculated. Therefore, even if only one test image is captured for each color (i.e., RGB), the first RGB-based gamma value to the k-th RGB-based gamma value to be applied to the first display area DP1 to the k-th display area DPk of the display panel 100 can be calculated using the gray level-driving current curves RCV, GCV, BCV according to RGB. Therefore, Figure 1 The gamma value calculation method can solve the problem in the prior art that the manufacturing process of the organic light-emitting display device is prolonged in order to set the RGB-based gamma values differently for each display area DP1,..., DPk of the display panel 100. Therefore, it can be easily applied to the mass production of the organic light-emitting display device.

[0075] As referred to Figures 1 to 4As described, according to the present invention, based on the first luminance value, second luminance value, and third luminance value respectively achieved by the first color pixel, second color pixel, and third color pixel included in the j-th display region at the first object gray level, it is possible to determine the first object gamma value to be applied to the first color pixel, the second gamma value to be applied to the second color pixel, and the third object gamma value to be applied to the third color pixel. For example, based on the gray level - driving current correspondence relationship between the first color and the second color, the second luminance value achieved by the second color pixel at the first object gray level can be used to predict the second object gray level corresponding to when the first color pixel achieves the second luminance value, and then the first object gamma value to be applied to the first color pixel can be determined. Similarly, based on the gray level - driving current correspondence relationship between the second color and the third color, the third luminance value achieved by the third color pixel at the first object gray level can be used to predict the third object gray level corresponding to when the second color pixel achieves the third luminance value, and then the second object gamma value to be applied to the second color pixel can be determined. Similarly, based on the gray level - driving current correspondence relationship between the third color and the first color, the first luminance value achieved by the first color pixel at the first object gray level can be used to predict the fourth object gray level corresponding to when the third color pixel achieves the first luminance value, and then the third object gamma value to be applied to the third color pixel can be determined. Thus, for each of the first color pixel to the third color pixel, only one test image (i.e., obtaining the corresponding luminance value) needs to be captured, and the first object gamma value to the third object gamma value to be applied to the first color pixel to the third color pixel can also be obtained.

[0076] Figure 5 is a flowchart showing an example of assigning gamma values to an object gray level region and a non - object gray level region by the gamma value calculation method of Figure 1 and Figure 6 is a diagram for explaining an example of assigning gamma values to an object gray level region and a non - object gray level region by the gamma value calculation method of Figure 1

[0077] Referring to Figure 5 and Figure 6 , Figure 1 's gamma calculation method can assign gamma values to the object gray level region TGR and the non - object gray level region NTGR after performing the steps S110, S120, S130, S140, and S150. Specifically, in Figure 1In the gamma calculation method, the object gamma value to be applied to the first color pixels included in the j-th display region DPj can be assigned to the object gray level region TGR to which the first object gray level FTG among all the gray levels MIG, .., MXG achieved by the first color pixels included in the j-th display region DPj belongs (S210), and the reference gamma value of the display panel 100 can be assigned to the non-object gray level region NTGR to which the first object gray level FTG does not belong among all the gray levels MIG, .., MXG achieved by the first color pixels included in the j-th display region DPj (S220). At this time, the object gray level region TGR can be a low gray level region less than or equal to the first object gray level FTG among all the gray levels MIG, ..., MXG achieved by the first color pixels included in the j-th display region DPj. For example, the object gray level region TGR can be a gray level region greater than or equal to the minimum gray level MIG and less than or equal to the first object gray level FTG. Conversely, the non-object gray level region NTGR can be a high gray level region greater than the first object gray level FTG among all the gray levels MIG, ..., MXG achieved by the first color pixels included in the j-th display region DPj. For example, the non-object gray level region NTGR can be a gray level region greater than the first object gray level FTG and less than or equal to the maximum gray level MXG. However, this is only exemplary, and the object gray level region TGR and the non-object gray level region NTGR can be set in various ways. Generally, when the same RGB-based gamma value is applied to all the display regions DP1, …, DPk of the display panel 100, the brightness deviation according to the display region is not large in a high gray level image, but the brightness deviation according to the display region is large in a low gray level image. Therefore, Figure 1 The gamma calculation method can assign the object gamma value (i.e., the RGB-based gamma value) calculated through the steps S110, S120, S130, S140, and S150 only to the object gray level region TGR (e.g., the low gray level region) among all the gray levels achieved by the pixels, and assign the reference gamma value (e.g., 2.2) of the display panel 100 to the non-object gray level region NTGR (e.g., the high gray level region) among all the gray levels achieved by the pixels.

[0078] Figure 7 is a block diagram showing an organic light emitting display device according to an embodiment of the present invention, Figure 8 is for explaining Figure 7 the brightness compensation performed by the organic light emitting display device.

[0079] Referring to Figure 7 and Figure 8 , the organic light emitting display device 500 may include a display panel 510, a scan driver 520, a data driver 530, a timing controller 540, and a memory device 550. In one embodiment, as Figure 7As shown, the memory device 550 may be located inside the timing controller 540. In another embodiment, the memory device 550 may be located outside the timing controller 540.

[0080] The display panel 510 may include a plurality of pixels. At this time, the pixels may include red pixels, green pixels, and blue pixels. In addition, at least one red pixel, at least one green pixel, and at least one blue pixel may constitute a unit pixel. In one embodiment, the unit pixel may have an RGB stripe structure. In another embodiment, the unit pixel may have a pentile structure. The display panel 510 may be connected to the scan driver 520 through scan lines and may be connected to the data driver 530 through data lines. The scan driver 520 may provide a scan signal SS to the display panel 510 through the scan lines. That is, the scan driver 520 may provide the scan signal SS to the pixels. The data driver 530 may provide a data signal DS (or data voltage) to the display panel 510 through the data lines. That is, the data driver 530 may provide the data signal DS to the pixels. The timing controller 540 may generate a plurality of control signals CTL1, CTL2 and provide them to the scan driver 520 and the data driver 530 to control the scan driver 520 and the data driver 530. The memory device 550 may store compensation parameters C-PAR according to display regions generated based on first RGB gamma values to k-th RGB gamma values respectively applied to the first display region to the k-th display region of the display panel 510 when manufacturing the organic light-emitting display device 500. In one embodiment, each of the first display region to the k-th display region of the display panel 510 may be constituted by a unit pixel including at least one red pixel, at least one green pixel, and at least one blue pixel. In another embodiment, each of the first display region to the k-th display region of the display panel 510 may be constituted by a plurality of unit pixels respectively including at least one red pixel, at least one green pixel, and at least one blue pixel. In addition, as Figure 8 shown, the timing controller 540 may perform brightness compensation of generating output image data CDATA by compensating input image data DATA generated from an external component (for example, a graphic processing unit (GPU)) based on the compensation parameters C-PAR according to display regions stored in the memory device 550. Therefore, the data driver 530 may convert the output image data CDATA into a data signal DS and provide it to the display panel 510. According to an embodiment, the organic light-emitting display device 500 may further include a light emission control driver that provides a light emission control signal to the display panel 510.

[0081] As described above, the compensation parameter C-PAR according to the display region for performing the brightness compensation can be generated based on the first RGB gamma value to the k-th RGB gamma value that will be respectively applied to the first display region to the k-th display region of the display panel 510 during the manufacture of the organic light emitting display device 500. At this time, the first RGB gamma value to the k-th RGB gamma value that will be respectively applied to the first display region to the k-th display region of the display panel 510 can be calculated as follows: By taking advantage of the fact that the luminance characteristics according to the input voltage of the red pixels, green pixels, and blue pixels included in each of the first display region to the k-th display region of the display panel 510 are similar, only one test image with a predetermined gray level is captured for each color (i.e., RGB) (for example, only a red test image with a predetermined gray level, a green test image with a predetermined gray level, and a blue test image with a predetermined gray level). Specifically, the first RGB gamma value to the k-th RGB gamma value that will be respectively applied to the first display region to the k-th display region of the display panel 510 can be calculated as follows: After displaying a first color test image with a first target gray level on the display panel 510, measuring the first luminance value achieved by at least one first color pixel included in the j-th display region through a luminance measuring device, after displaying a second color test image with a first target gray level on the display panel 510, measuring the second luminance value achieved by at least one second color pixel included in the j-th display region through a luminance measuring device, deriving a predicted drive current flowing through the second color pixel at the first target gray level based on the RGB gray level-drive current curve, deriving a second target gray level when the predicted drive current flows through the first color pixel based on the RGB gray level-drive current curve, and calculating the target gamma value to be applied to the first color pixel included in the j-th display region based on the first target gray level, the second target gray level, the first luminance value achieved by at least one first color pixel included in the j-th display region at the first target gray level, and the second luminance value achieved by at least one second color pixel included in the j-th display region at the first target gray level. In addition, the RGB gray level-drive current curve can be predetermined at the design stage of the display panel 510 according to the characteristics of the drive transistors and organic light emitting diodes designed to be included in the first color pixel and the second color pixel. In one embodiment, the target gamma value to be applied to the first color pixel included in the j-th display region can be calculated by the above [Equation 1]. In this case, the target gamma value to be applied to the first color pixel included in the j-th display region can be calculated independently of the reference display region gamma value set for the reference display region (for example, the central display region). In another embodiment, the target gamma value to be applied to the first color pixel included in the j-th display region can be calculated by the above [Equation 2].In this case, the object gamma value to be applied to the first color pixels included in the j-th display region can be calculated by reflecting the reference display region gamma value set for a reference display region (e.g., the central display region). However, since this has been described above, a repeated description thereof will be omitted.

[0082] Figure 9 is a block diagram showing an electronic device according to an embodiment of the present invention, Figure 10 shows Figure 9 An example in which the electronic device is implemented as a smart phone.

[0083] Reference Figure 9 and Figure 10 , the electronic device 1000 may include a processor 1010, a memory device 1020, a storage device 1030, an input / output device 1040, a power supply 1050, and an organic light-emitting display device 1060. At this time, the organic light-emitting display device 1060 may be Figure 7 The display device 500. Also, the electronic device 1000 may further include a plurality of ports capable of communicating with a graphics card, a sound card, a memory card, a USB device, etc. or communicating with other systems. In one embodiment, as Figure 10 shown, the electronic device 1000 may be implemented as a smart phone. However, this is merely exemplary, and the electronic device 1000 is not limited thereto. For example, the electronic device 1000 may also be implemented as a portable phone, a video phone, a smart tablet, a smart watch, a tablet PC, a vehicle navigator, a computer monitor, a notebook computer, a head-mounted display device, etc.

[0084] The processor 1010 can perform specific calculations or tasks. According to an embodiment, the processor 1010 can be a microprocessor, a central processing unit, an application processor, etc. The processor 1010 can be connected to other components via an address bus, a control bus, a data bus, etc. According to an embodiment, the processor 1010 can also be connected to an expansion bus such as a Peripheral Component Interconnect (PCI) bus. The memory device 1020 can store data required for the operation of the electronic device 1000. For example, the memory device 1020 can include non-volatile storage devices such as an Erasable Programmable Read-Only Memory (EPROM) device, an Electrically Erasable Programmable Read-Only Memory (EEPROM) device, a flash memory device, a Phase Change Random Access Memory (PRAM) device, a Resistance Random Access Memory (RRAM) device, a Nano Floating Gate Memory (NFGM) device, a Polymer Random Access Memory (PoRAM) device, a Magnetic Random Access Memory (MRAM) device, a Ferroelectric Random Access Memory (FRAM) device, etc. and / or volatile storage devices such as a Dynamic Random Access Memory (DRAM) device, a Static Random Access Memory (SRAM) device, a mobile DRAM device, etc. The storage device 1030 can include a Solid State Drive (SSD), a Hard Disk Drive (HDD), a CD-ROM, etc.The input / output device 1040 may include an input unit such as a keyboard, keypad, touchpad, touch screen, mouse, etc. and an output unit such as a speaker, printer, etc. According to an embodiment, the organic light emitting display device 1060 may also be included in the input / output device 1040. The power supply 1050 may supply power required for the operation of the electronic device 1000. The organic light emitting display device 1060 may be connected to other components through the bus or other communication links.

[0085] The organic light emitting display device 1060 may display an image corresponding to the visual information of the electronic device 1000. At this time, the organic light emitting display device 1060 may improve the image quality by performing brightness compensation. To this end, the organic light emitting display device 1060 may include a display panel including pixels, a scan driver that provides a scan signal to the display panel, a data driver that provides a data signal to the display panel, a timing controller that controls the scan driver and the data driver, a memory device that stores compensation parameters according to the display area, and the like. According to an embodiment, the organic light emitting display device 1060 may further include a light emission control driver that provides a light emission control signal to the display panel. In addition, the timing controller may perform brightness compensation for generating output image data by compensating the input image data based on the compensation parameters according to the display area stored in the memory device. To this end, when manufacturing the organic light emitting display device 1060, the compensation parameters according to the display area may be generated based on the first RGB-based gamma value to the k-th RGB-based gamma value that will be respectively applied to the first display area to the k-th display area of the display panel. In addition, the first RGB-based gamma value to the k-th RGB-based gamma value that will be respectively applied to the first display area to the k-th display area of the display panel may be calculated as follows: after displaying a first color test image having a first target gray level on the display panel, measuring a first brightness value realized by at least one first color pixel included in the j-th display area through a brightness measurement device, after displaying a second color test image having a first target gray level on the display panel, measuring a second brightness value realized by at least one second color pixel included in the j-th display area through a brightness measurement device, deriving a predicted drive current flowing through the second color pixel at the first target gray level based on the gray level-drive current curve according to RGB, deriving a second target gray level when the predicted drive current flows through the first color pixel based on the gray level-drive current curve according to RGB, and calculating the target gamma value to be respectively applied to the first color pixel included in the j-th display area based on the first target gray level, the second target gray level, the first brightness value realized by at least one first color pixel included in the j-th display area at the first target gray level, and the second brightness value realized by at least one second color pixel included in the j-th display area at the first target gray level. However, since this has been described above, a repeated description thereof will be omitted.

[0086] Industrial applicability

[0087] The present invention can be applied to an organic light emitting display device and an electronic device including the same. For example, the present invention can be applied to a portable phone, a smart phone, a video phone, a smart tablet, a smart watch, a tablet computer, a vehicle navigation system, a television, a computer monitor, a notebook computer, a head-mounted display (HMD) device, an MP3 player, etc.

[0088] Although the above has been described with reference to exemplary embodiments of the present invention, those of ordinary skill in the art can understand that various modifications and changes can be made to the present invention without departing from the spirit of the present invention described in the claims and the scope of the technical field.

Claims

1. A method for calculating gamma values for a display panel, the method for calculating gamma values for a display panel calculating first gamma values according to colors to k-th gamma values according to colors that are to be applied to a first display area to a k-th display area respectively, wherein, k is an integer of 2 or more, and is characterized by including the following steps: Measuring a first luminance value achieved by at least one first-color pixel included in the j-th display region at a first object gray level, where j is an integer of 1 or more and k or less; Measuring a second luminance value achieved by at least one second-color pixel included in the j-th display region at the first object gray level; Deriving a predicted drive current flowing through the second-color pixel at the first object gray level based on the gray level-drive current correspondence relationship of the second color; Deriving a second object gray level when the predicted drive current flows through the first-color pixel based on the gray level-drive current correspondence relationship of the first color; and Calculating an object gamma value to be applied to the first-color pixel included in the j-th display region based on the first object gray level, the second object gray level, the first luminance value, and the second luminance value.

2. The method for calculating a gamma value for a display panel according to claim 1, wherein The gray level-drive current correspondence relationships of the first color and the second color are predetermined at the design stage of the display panel according to the characteristics of the drive transistors and organic light-emitting diodes designed to be included in the first-color pixel and the second-color pixel.

3. The method for calculating a gamma value for a display panel according to claim 1, wherein The first-color pixel is one of a red pixel, a green pixel, and a blue pixel, and the second-color pixel is a pixel having a color different from that of the first-color pixel among the red pixel, the green pixel, and the blue pixel.

4. The method for calculating a gamma value for a display panel according to claim 2, wherein The gray level-drive current correspondence relationships of the first color and the second color are respectively gray level-drive current curves of the first color and the second color.

5. The method for calculating a gamma value for a display panel according to claim 1, wherein The step of measuring a first luminance value achieved by at least one first-color pixel included in the j-th display region at the first object gray level includes: After displaying a first-color test image having the first object gray level on the display panel, measuring a first luminance value achieved by at least one first-color pixel included in the j-th display region with a luminance measuring device, wherein the step of measuring a second luminance value achieved by at least one second-color pixel included in the j-th display region at the first object gray level includes: After displaying a second-color test image having the first object gray level on the display panel, measuring a second luminance value achieved by at least one second-color pixel included in the j-th display region with the luminance measuring device.

6. The gamma value calculation method for a display panel according to claim 1, wherein It further includes the following steps: Assigning the object gamma value to the object gray level region to which the first object gray level belongs among all the gray levels achieved by the first-color pixel; and Assigning the reference gamma value of the display panel to the non-object gray level region to which the first object gray level does not belong among all the gray levels achieved by the first-color pixel.

7. The gamma value calculation method for a display panel according to claim 6, wherein the object gray-scale region is a low gray-scale region of all the gray-scales achieved by the first color pixels that is less than or equal to the first object gray-scale.

8. The gamma value calculation method for a display panel according to claim 1, wherein the first luminance value is the arithmetic mean luminance value of the first color pixels included in the j-th display region, and the second luminance value is the arithmetic mean luminance value of the second color pixels included in the j-th display region.

9. The gamma value calculation method for a display panel according to claim 1, wherein the first luminance value is the weighted mean luminance value of the first color pixels included in the j-th display region, and the second luminance value is the weighted mean luminance value of the second color pixels included in the j-th display region.

10. The gamma value calculation method for a display panel according to claim 1, wherein the first luminance value is the luminance value of one pixel among the first color pixels included in the j-th display region, and the second luminance value is the luminance value of one pixel among the second color pixels included in the j-th display region.

Images