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EP-3869492-B1 - DISPLAY DEVICE

EP3869492B1EP 3869492 B1EP3869492 B1EP 3869492B1EP-3869492-B1

Inventors

  • PYUN, KI HYUN
  • PARK, HEE SOOK

Dates

Publication Date
20260506
Application Date
20210208

Claims (11)

  1. A display device comprising: a plurality of pixels (PXij) configured to receive data voltages determined by a gain value and input grayscale values; a current sensor (15) configured to provide a sensing value (SSC) of a current flowing in a first power line, wherein the first power line is commonly coupled to the pixels; an initial gain provider (16) configured to provide an initial gain value (IGA, IGB, IGC) based on the sensing value such that the sensing value does not exceed a current limit value (CLM); a grayscale converter (18) configured to convert the input grayscale values into output grayscale values, based on the gain value, by multiplying each input grayscale value with the gain value; a timing controller (11) configured to provide the output grayscale values to a data driver (12); the data driver (12), configured to convert the output grayscale values into the data voltages and provide the data voltages to the plurality of pixels; a gain provider (17) comprising a load comparator configured to generate an enable signal when a difference between a load value of a first frame and the load value of a second frame next to the first frame is smaller than an enable threshold value, wherein the load value of each frame is a value obtained by adding up the input grayscale values of the frame or is an average value of the input grayscale values of the frame, wherein the initial gain provider is configured to set the initial gain value to 1 when the sensing value is smaller than the current limit value (CLM), and to a value which is less than 1, and which decreases as the load value of a current frame increases, when the sensing value reaches the current limit value (CLM), the gain provider being configured to: in response to the generated enable signal: determine a length of a first period according to a first load value based on the input grayscale values at the time (t0) at which the enable signal is generated, wherein the first load value is equal to the load value of the second frame, and wherein the first period is determined to become shorter as the first load value becomes smaller; maintain the gain value at the initial gain value (IGA, IGB, IGC) during the first period; gradually decrease the gain value from a first time (t1a, t1b, t1c) until the gain value reaches a minimum gain value (GSAT) at a second time (t2; t2a, t2b, t2c), the first time (t1a, t1b, t1c) being when the first period elapses, wherein the first period is a period starting at a time (t0) at which an enable signal is generated; and maintain the gain value at the minimum gain value (GSAT) from the second time, and set an interval between the time (t0) at which the enable signal is generated and the second time (t2; t2a, t2b, t2c) either to a constant time regardless of the first load value, or to a longer time as the first load value becomes smaller.
  2. The display device of claim 1, wherein the gain provider includes: a first frame counter configured to provide a first count value of frames from the time (t0) at which the enable signal is generated; and a set gain controller configured to determine the first period, based on the first load value and the first count value.
  3. The display device of claim 2, wherein the set gain controller includes a plurality of set gain lookup tables different from each other according to the first load value.
  4. The display device of claim 3, wherein the set gain controller is configured to provide a first gain ratio value corresponding to the first count value with reference to a set gain lookup table selected according to the first load value.
  5. The display device of claim 4, wherein the gain provider further includes a gain converter configured to convert the initial gain value into the gain value according to the first gain ratio value.
  6. The display device of claim 5, wherein the first gain ratio value is equal to 1 or less than 1.
  7. The display device of claim 6, wherein the gain provider is configured to gradually increase the gain value from a third time after the second time.
  8. The display device of claim 7, wherein the gain provider is configured to determine an increase rate of the gain value according to a second load value based on the input grayscale values at the third time.
  9. The display device of claim 8, wherein the gain provider is configured to determine an increase rate of the gain value according to a difference between the second load value and the first load value.
  10. The display device of claim 8 or claim 9, wherein the load comparator is configured to generate a disable signal when a difference between the load value of a third frame and the load value of a fourth frame next to the third frame is greater than a disable threshold value, and wherein the gain provider includes: a second frame counter configured to provide a second count value of frames from a time at which the disable signal is generated; and a reset gain controller configured to determine the increase rate based on the second load value and the second count value.
  11. The display device of claim 10, wherein the reset gain controller includes a plurality of reset gain lookup tables different from each other according to the second load value, wherein the reset gain controller is configured to provide a second gain ratio value corresponding to the second count value with reference to a reset gain lookup table selected according to the second load value, wherein the gain converter is configured to convert the initial gain value into the gain value according to the second gain ratio value, and wherein the second gain ratio value is equal to 1 or less than 1.

Description

BACKGROUND 1. Technical Field Generally, the present disclosure generally relates to a display device. More particularly, the present disclosure relates to a display device capable of reducing a flicker according to an image pattern while using a screen saver function. 2. 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 a liquid crystal display device, an organic light emitting display device, and a plasma display device are increasingly used. A display device may include a plurality of pixels, and display a frame through a combination of lights emitted from the pixels. When a plurality of frames are sequentially displayed, a user may recognize the frames as an image (moving image or still image). When a still image is displayed, occurrence of an afterimage can be prevented and power consumption can be reduced, by using a screen saver function of decreasing a luminance of an image. However, it is necessary to increase the luminance of the image again when the still image is changed to a moving image, and a flicker occurs according to an image pattern. Thus, there is need to develop a novel display device to increase display quality and reduce power consumption. US 2019/213953, US 2008/284702 and US 2010/060554 all make disclosures related to display devices. SUMMARY According to an aspect, there is provided a display device according to Claim 1. Details of embodiments are provided in the dependent claims. The present embodiments provide a display device capable of reducing a flicker according to an image pattern while using a screen saver function. In accordance with an aspect of the present disclosure, there is provided a display device including a gain provider configured to gradually decrease a gain value from a first time when a first period elapses from a time at which an enable signal is generated, and a plurality of pixels configured to receive data voltages determined by the gain value and the input grayscale values, wherein the gain provider determines a length of the first period according to a first load value based on input grayscale values at the time at which the enable signal is generated. The gain provider determines the first period to become shorter as the first load value becomes smaller. The gain provider maintains the gain value from a second time after the first time. An interval between the time at which the enable signal is generated and the second time set constant regardless of the first load value. Alternatively, the interval between the time at which the enable signal is generated and the second time is set longer as the first load value becomes smaller. The gain provider includes a load comparator configured to generate the enable signal when a difference between a load value of a first frame and a load value of a second frame is smaller than an enable threshold value. The gain provider may include a first frame counter configured to provide a first count value of frames from the time at which the enable signal is generated, and a set gain controller configured to determine the first period, based on the first load value and the first count value. The set gain controller may include a plurality of set gain lookup tables different from each other according to the first load value. The set gain controller may provide a first gain ratio value corresponding to the first count value with reference to a set gain lookup table selected according to the first load value. The display device further includes a current sensor configured to provide a sensing value of a current flowing in a first power line, and includes an initial gain provider configured to provide an initial gain value, based on the sensing value. The first power line is commonly coupled to the pixels. The gain provider further may include a gain converter configured to convert the initial gain value into the gain value according to the first gain ratio value. The initial gain provider provides the initial gain value such that the sensing value is smaller than a current limit value. The first gain ratio value may be equal to 1 or less than 1. The gain provider may gradually increase the gain value from a third time after the second time. The gain provider may determine an increase rate of the gain value according to a second load value based on the input grayscale values at the third time. The gain provider may determine an increase rate of the gain value according to a difference between the second load value and the first load value. The load comparator may generate a disable signal when a difference between a load value of a third frame and a load value of a fourth frame is greater than a disable threshold value. The gain provider may include a second frame counter configured to provide a second count value of frames from a time at which the disable signal is generat