BACKGROUND

1. Field

Example embodiments of the inventive concept relate to display devices. More particularly, example embodiments of the inventive concept relate to image sticking compensating devices and display devices having the same.

2. Discussion of Related Art

A display device (an organic light emitting display device) accumulates age information (e.g., stress information or degradation degree information) using an image sticking compensation technique and eliminates image sticking by compensating the age (or the stress) of every pixel based on the accumulated data. For example, the stress (or the degradation, age) information may be accumulated based on a current flowing into each pixel at each frame, an emission time of each pixel, a temperature of a display panel, and/or the like.

However, the typical stress accumulation methods apply the same compensation values to all the grayscale levels regardless of display grayscale according to the accumulated stress information. Thus, the image sticking may be recognized at some grayscale levels in which improper compensation is performed in an actual display panel.

SUMMARY

Example embodiments provide an image sticking compensating device for determining grayscale compensation values based on age data having accumulated degradation information and input grayscales.

Example embodiments provide a display device including the image sticking compensating device.

According to example embodiments, a display device may comprise a degradation calculator configured to calculate a degradation weight based on input image data, and to calculate degradation data of a frame, an accumulator configured to accumulate the degradation data, and to generate age data using the accumulated degradation data, and a compensator configured to determine a grayscale compensation value corresponding to the age data and an input grayscale of the input image data, and to output age compensation data by applying the grayscale compensation value to the input image data.

In example embodiments, the image sticking compensating device may further comprise a grayscale scaler configured to generate a scaled input grayscale based on a scaling ratio corresponding to the age data to prevent the grayscale compensation value from saturating according to the accumulated degradation data.

In example embodiments, the compensator may comprise a memory including a plurality of lookup tables each having compensation values respectively corresponding to a plurality of predetermined age values and display grayscales implemented by a display panel, each of the age values matching a corresponding one of the age data, a compensation value determiner configured to determine the grayscale compensation value corresponding to the age data and the scaled input grayscale through the lookup tables, and a compensation data output configured to output the age compensation data by applying the grayscale compensation value to the scaled input grayscale data.

In example embodiments, the lookup tables may be set based on pixel colors in the display panel and predetermined temperatures of the display panel, respectively.

In example embodiments, the compensation value determiner may be configured to select one of the lookup tables based on a current temperature of the display panel and a pixel color.

In example embodiments, pixel colors may include a red, a green, and a blue.

In example embodiments, the compensator may be configured to divide the display panel into a plurality of blocks, determine block weight corresponding to each of the blocks, further apply the block weight to the age data, and determine the grayscale compensation value based on the age data to which the block weight is applied.

In example embodiments, the degradation weight may include at least one of a location weight calculated based on a location of a pixel corresponding to the input image data, a luminance weight calculated based on the input grayscale corresponding to the input image data, and a temperature weight calculated based on a current temperature of the display panel.

In example embodiments, the degradation weight may further include an emission duty weight calculated based on an emission duty corresponding to the input image data and an emission frequency weight calculated based on an emission frequency corresponding to the input image data.

In example embodiments, the compensator may comprise a first calculator configured to calculate a target luminance corresponding to the scaled input grayscale using a predetermined reference grayscale-luminance function, a function corrector configured to correct the reference grayscale-luminance function to a target function for corresponding to the age data and a current temperature of a display panel, and a second calculator configured to calculate the grayscale compensation value corresponding to the target luminance by calculating an inverse function of the target function.

In example embodiments, the target function may include a plurality of different auxiliary functions each defined in a plurality of predetermined grayscale sections.

In example embodiments, auxiliary functions may be continuous with each other.

In example embodiments, the degradation weight may include at least one of a location weight calculated based on a location of a pixel corresponding to the input image data, a luminance weight calculated based on the input grayscale corresponding to the input image data, and a temperature weight calculated based on a current temperature of the display panel.

In example embodiments, the degradation weight may further include an emission duty weight calculated based on an emission duty corresponding to the input image data and an emission frequency weight calculated based on an emission frequency corresponding to the input image data.

In example embodiments, the grayscale scaler may be configured to provide the scaled input grayscale to the accumulator, and the accumulator may be configured to generate the age data by accumulating the degradation data and the scaled input grayscale.

In example embodiments, the compensator may be configured to provide the age compensation data to the accumulator, and the accumulator may be configured to generate the age data by accumulating the degradation data and a grayscale of the age compensation data.

In example embodiments, the image sticking compensating device may further comprise a gamma corrector configured to convert the scaled input grayscale into a gamma voltage represented in a voltage domain for transferring to a data driver. The compensator may be configured to convert the age compensation data into a grayscale voltage in the voltage domain based on the gamma voltage and the age data.

According to example embodiments, a display device may comprise a display panel including a plurality of pixels, an image sticking compensator configured to output age compensation data based on age data and input image data, a scan driver configured to provide a scan signal to the display panel, a data driver configured to provide a data signal corresponding to the age compensation data to the display panel, and a timing controller configured to control the scan driver and the data driver. The image sticking compensator may comprise a degradation calculator configured to calculate a degradation weight based on input image data and to calculate degradation data of a frame, an accumulator configured to accumulate the degradation data and to generate age data using the accumulated degradation data, a grayscale scaler configured to generate a scaled input grayscale based on a scaling ratio corresponding to the age data, and a compensator configured to determine a grayscale compensation value corresponding to the age data and an input grayscale of the input image data, and to output age compensation data by applying the grayscale compensation value to the input image data.

In example embodiments, the compensator may comprise a memory including a plurality of lookup tables each having compensation values respectively corresponding to a plurality of predetermined age values and display grayscales implemented by a display panel, each of the age values matching a corresponding one of the age data, a compensation value determiner configured to determine the grayscale compensation value corresponding to the age data and the scaled input grayscale through the lookup tables, and a compensation data output configured to output the age compensation data by applying the grayscale compensation value to the scaled input grayscale data.

In example embodiments, the compensator may comprise a first calculator configured to calculate a target luminance corresponding to the scaled input grayscale using a predetermined reference grayscale-luminance function, a function corrector configured to correct the reference grayscale-luminance function to a target function for corresponding to the age data and a current temperature of a display panel, and a second calculator configured to calculate the grayscale compensation value corresponding to the target luminance by calculating an inverse function of the target function.

Therefore, the image sticking display device and the display device having the same according to example embodiments may accumulate the degradation data (i.e., generate the age data) with respect to the each of the pixels reflecting location characteristics in the display panel, emission information, temperature, etc, such that accurate amount of degradation of each pixel may be calculated. The image sticking display device may include the compensator to calculating the optimized grayscale compensation value based on the age data and the input grayscales such that accuracy of image sticking compensation may be significantly improved. Further, since individual compensation for all grayscale levels may be performed, the image sticking with respect to all the grayscale levels may be not recognized.

In addition, the image sticking compensating device may calculate the grayscale compensation value in both grayscale domain condition and voltage domain condition so as to be applied to various display devices regardless of the types of pixel circuit and the types of panel driving method.

