CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean patent application 10-2018-0120765 filed on Oct. 10, 2018 in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference.

BACKGROUND

1. Field

The present disclosure generally relates to a display device.

2. Description of the Related Art

With the development of information technologies, the importance of a display device, which is a connection medium between a user and information, increases. Accordingly, display devices such as liquid crystal display devices and organic light emitting display devices are increasingly used.

An organic light emitting display device includes a plurality of pixels, and displays an image frame by allowing organic light emitting diodes of the plurality of pixels to emit lights so as to correspond to a plurality of grayscale values constituting the image frame.

In general, in the organic light emitting display device, grayscale voltages are set to exhibit a luminance according to a gamma curve more suitable for a white color light radiated when pixels of different colors emit lights with the same grayscale value.

Therefore, when a mixed color light or a single color light is radiated instead of the white color light, using the set grayscale voltages, the luminance of the mixed color light or the single color light does not exactly correspond to the above-described gamma curve. In addition, there exists a lateral leakage problem in that, when the single color light is radiated, holes of driving current flowing in a corresponding pixel are leaked to an adjacent pixel having a small resistance through a P-doped Hole Injection Layer (PHIL) that is a layer shared by the organic light emitting diodes, and therefore, the corresponding pixel does not emit light with a desired luminance.

SUMMARY

Embodiments provide a display device capable of exhibiting a desired luminance not only when a white color light is radiated but also when a single color light or a mixed color light is radiated.

According to an aspect of the present disclosure, there is provided a display device including: a target pixel; observation target pixels located adjacent to the target pixel; and a grayscale corrector configured to convert an input grayscale value corresponding to the target pixel with reference to observation target grayscale values corresponding to the observation target pixels, wherein the grayscale corrector includes: a light emitting pixel counter configured to provide a number of light emitting pixels by counting a number of observation target grayscale values that exceed a reference value; and a grayscale converter configured to provide a converted grayscale value by converting the input grayscale value, based on the number of light emitting pixels.

The grayscale corrector may further include a single color offset provider configured to provide single color offset values. When the number of light emitting pixels is 0, the grayscale converter may generate the converted grayscale value by adding a corresponding offset value from among the single color offset values to the input grayscale value.

The grayscale corrector may further include a mixed color offset provider configured to provide mixed color offset values. When the number of light emitting pixels is greater than 0 and is less than the number of observation target pixels, the grayscale converter may generate the converted grayscale value by adding a corresponding offset value from among the mixed color offset values to the input grayscale value.

When the number of light emitting pixels is equal to the number of observation target pixels, the grayscale converter may determine the input grayscale value as the converted grayscale value.

The single color offset provider may include: a reference offset provider configured to receive an input maximum luminance value, and to provide reference offset values corresponding to the input maximum luminance value; and a total offset generator configured to generate single color offset values by interpolating the reference offset values.

The reference offset provider may include a preset determiner configured to store, in advance, preset offset values corresponding to preset maximum luminance values, and to determine whether the input maximum luminance value corresponds to any one of the preset maximum luminance values. When the input maximum luminance value corresponds to any one of the preset maximum luminance values, the preset determiner may provide the corresponding preset offset values as the reference offset values.

When the input maximum luminance value does not correspond to any one of the preset maximum luminance values, the preset determiner may provide the preset offset values corresponding to at least two preset maximum luminance values. The reference offset provider may further include a reference offset generator configured to generate the reference offset values by interpolating the preset offset values corresponding to the at least two preset maximum luminance values.

The preset maximum luminance values may include a maximum value and a minimum value of a receivable input maximum luminance value.

The preset maximum luminance values may further include a first intermediate maximum luminance value. When the input maximum luminance value is between the maximum value and the first intermediate maximum luminance value, a grayscale voltage corresponding to the converted grayscale value may be adjusted corresponding to the input maximum luminance value, so that the luminance of the target pixel is controlled.

When the input maximum luminance value is between the minimum value and the first intermediate maximum luminance value, an emission period of the target pixel may be adjusted corresponding to the input maximum luminance value, so that the luminance of the target pixel is controlled.

The preset maximum luminance values may further include a second intermediate maximum luminance value that is between the first intermediate maximum luminance value and the minimum value.

The target pixel may be a pixel that emits light of a first color with a luminance corresponding to the converted grayscale value, and at least some of the observation target pixels may be pixels that emit light of a second color different from the first color.

At least some of the observation target pixels may be pixels that emit light of a third color different from the first color and the second color.

The grayscale corrector may further include a single color offset provider configured to provide single color offset values. When the number of light emitting pixels is 0, the grayscale converter may generate the converted grayscale value by adding a corresponding offset value from among the single color offset values to the input grayscale value.

The grayscale corrector may further include a mixed color offset provider configured to provide mixed color offset values. When the number of light emitting pixels is greater than 0 and is less than the number of observation target pixels, the grayscale converter may generate the converted grayscale value by adding a corresponding offset value from among the mixed color offset values to the input grayscale value.

When the number of light emitting pixels is equal to the number of observation target pixels, the grayscale converter may determine the input grayscale value as the converted grayscale value.

At least some of the observation target pixels may be pixels that emit light of the first color.

The grayscale corrector may further include a single color offset provider configured to provide single color offset values. When the number of light emitting pixels corresponding to the second color and the third color is 0, the grayscale converter may generate the converted grayscale value by adding a corresponding offset value from among the single color offset values to the input grayscale value.

The grayscale corrector may further include a mixed color offset provider configured to provide mixed color offset values. When the number of light emitting pixels corresponding to the second color and the third color is not 0 and is less than the number of observation target pixels corresponding to the second color and the third color, the grayscale converter may generate the converted grayscale value by adding a corresponding offset value from among the mixed color offset values to the input grayscale value.

When the number of light emitting pixels corresponding to the second color and the third color is equal to the number of observation target pixels corresponding to the second color and the third color, the grayscale converter may determine the input grayscale value as the converted grayscale value.

According to another aspect of the present disclosure, there is provided a display device including: a first pixel configured to emit light of a first color; a second pixel configured to emit light of a second color different from the first color; a third pixel configured to emit light of a third color different from the first color and the second color; and a grayscale corrector configured to convert input grayscale values corresponding to the first, second, and third pixels to converted grayscale values, wherein the first, second, and third pixels are configured to emit lights, based on the converted grayscale values, wherein a first luminance of the first pixel in a first case where the first pixel, the second pixel, and the third pixel emit lights is different from a second luminance of the first pixel in a second case where only the first pixel emits light and the second and third pixels do not emit light, wherein an input grayscale value corresponding to the first pixel in the first case is equal to that corresponding to the first pixel in the second case, and a converted grayscale value corresponding to the first luminance is different from that corresponding to the second luminance.

