Display apparatus and method of operating the same

A display apparatus may include a display timing controller and a display panel. The display timing controller generates first output image data based on first input image data and a first gamma function, and generates second output image data based on second input image data and a second gamma function. The display panel operates based on the first output image data during a first duration, and operates based on the second output image data during a second duration subsequent to the first duration. The first and second gamma functions correspond to a first region of the display panel, and a luminance of an image based on the first gamma function is different from a luminance of an image based on the second gamma function.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC § 119 to Korean Patent Application No. 10-2015-0120412, filed on Aug. 26, 2015 in the Korean Intellectual Property Office (KIPO), the contents of which are herein incorporated by reference in their entirety.

TECHNICAL FIELD

The inventive concept relates generally to displaying images, and more particularly to display apparatuses and methods of operating the display apparatuses.

DISCUSSION OF RELATED ART

A liquid crystal display apparatus is a type of flat panel display (FPD), which is widely used in recent years. The FPD may include, but is not limited to, a liquid crystal display (LCD), a plasma display panel (PDP) and an organic light emitting display (OLED), for example.

A display panel in the display apparatus includes a plurality of pixels. Each pixel includes a pixel electrode receiving a data voltage and a common electrode receiving a common voltage. An image having a target luminance may be displayed on the display panel based on a difference between the data voltage and the common voltage. However, a residual direct current (DC) voltage can be generated in the display panel due to various reasons, such as a discord between an electric center of the data voltage and the common voltage. The residual DC voltage can cause an afterimage or a sticking image.

SUMMARY

At least one exemplary embodiment of the present disclosure provides a display apparatus capable of high display quality.

At least one exemplary embodiment of the present disclosure provides a method of operating the display apparatus.

According to an exemplary embodiment, a display apparatus includes a timing controller and a display panel. The timing controller generates first output image data based on first input image data and a first gamma lookup table, and generates second output image data based on second input image data and a second gamma lookup table. The display panel operates based on the first output image data during a first duration, and operates based on the second output image data during a second duration subsequent to the first duration. The first and second gamma lookup tables correspond to a first region of the display panel, and a luminance of an image based on the first gamma lookup table is different from a luminance of an image based on the second gamma lookup table.

In an exemplary embodiment, the timing controller may further perform a temporal smoothing operation to reduce discontinuity between the first output image data and the second output image data during a third duration between the first duration and the second duration.

The timing controller may further generate at least one smoothing image data by performing an interpolation based on the first output image data and the second output image data. The display panel may operate based on the at least one smoothing image data during the third duration.

In an exemplary embodiment, the luminance of the image based on the first gamma lookup table may be higher than the luminance of the image based on the second gamma lookup table.

In an exemplary embodiment, a residual direct current (DC) voltage in the display panel may increase during the first duration and may decrease during the second duration.

In an exemplary embodiment, the timing controller may further generate third output image data based on third input image data and a third gamma lookup table, and may further generate fourth output image data based on fourth input image data and one of the third gamma lookup table and a fourth gamma lookup table. The display panel may operate based on the first output image data and the third output image data during the first duration, and may operate based on the second output image data and the fourth output image data during the second duration. The third and fourth gamma lookup tables may correspond to a second region of the display panel, and a luminance of an image based on the third gamma lookup table may be different from the luminance of the image based on the first gamma lookup table and a luminance of an image based on the fourth gamma lookup table.

In an exemplary embodiment, the timing controller may further perform a spatial smoothing operation to reduce discontinuity between the first output image data and the third output image data during the first duration.

In an exemplary embodiment, the timing controller may further generate third output image data based on third input image data and the first gamma lookup table, and may further generate fourth output image data based on fourth input image data and the second gamma lookup table. The display panel may operate based on the third output image data during a third duration subsequent to the second duration, and may operate based on the fourth output image data during a fourth duration subsequent to the third duration.

In an exemplary embodiment, the timing controller may further generate third output image data based on third input image data and the first gamma lookup table, and may further generate fourth output image data based on fourth input image data and a third gamma lookup table. The display panel may operate based on the third output image data during a third duration subsequent to the second duration, and may operate based on the fourth output image data during a fourth duration subsequent to the third duration. The third gamma lookup table may correspond to the first region of the display panel, and a luminance of an image based on the third gamma lookup table may be different from the luminance of the image based on the first gamma lookup table and the luminance of the image based on the second gamma lookup table.

In an exemplary embodiment, the luminance of the image based on the first gamma lookup table may be lower than the luminance of the image based on the second gamma lookup table, and may be higher than the luminance of the image based on the third gamma lookup table.

In an exemplary embodiment, a length of at least one of the first duration and the second duration may be variable.

In an exemplary embodiment, the timing controller may determine a type of a first image displayed on the display panel based on the first output image data and the second output image data, and may change the length of the at least one of the first duration and the second duration based on the type of the first image.

In an exemplary embodiment, the timing controller may increase the length of the at least one of the first duration and the second duration when the first image corresponds to a dynamic image, and may decrease the length of the at least one of the first duration and the second duration when the first image corresponds to a static image.

In an exemplary embodiment, the timing controller may change the length of the at least one of the first duration and the second duration based on a flag signal indicating a type of an image displayed on the display panel.

According to an exemplary embodiment, in a method of operating a display apparatus, first output image data is generated based on first input image data and a first gamma lookup table. Second output image data is generated based on second input image data and a second gamma lookup table. A display panel in the display apparatus operates based on the first output image data during a first duration. The display panel operates based on the second output image data during a second duration subsequent to the first duration. The first and second gamma lookup tables correspond to a first region of the display panel, and a luminance of an image based on the first gamma lookup table is different from a luminance of an image based on the second gamma lookup table.

In an exemplary embodiment, a temporal smoothing operation may be further performed to reduce discontinuity between the first output image data and the second output image data during a third duration between the first duration and the second duration.

At least one smoothing image data may be generated by performing an interpolation based on the first output image data and the second output image data. The display panel may operate based on the at least one smoothing image data during the third duration.

In an exemplary embodiment, third output image data may be generated based on third input image data and a third gamma lookup table. Fourth output image data may be generated based on fourth input image data and one of the third gamma lookup table and a fourth gamma lookup table. The display panel may operate based on the third output image data during the first duration. The display panel may operate based on the fourth output image data during the second duration. The third and fourth gamma lookup tables may correspond to a second region of the display panel, and a luminance of an image based on the third gamma lookup table may be different from the luminance of the image based on the first gamma lookup table and a luminance of an image based on the fourth gamma lookup table.

In an exemplary embodiment, third output image data may be generated based on third input image data and the first gamma lookup table. Fourth output image data may be generated based on fourth input image data and a third gamma lookup table. The display panel may operate based on the third output image data during a third duration subsequent to the second duration. The display panel may operate based on the fourth output image data during a fourth duration subsequent to the third duration. The third gamma lookup table may correspond to the first region of the display panel, and a luminance of an image based on the third gamma lookup table may be different from the luminance of the image based on the first gamma lookup table and the luminance of the image based on the second gamma lookup table.

In an exemplary embodiment, a length of at least one of the first duration and the second duration may be further changed based on a type of an image displayed on the display panel based on the first output image data and the second output image data.

An exemplary embodiment display timing controller includes a gamma compensator configured to provide a plurality of output data sets for a corresponding plurality of successive time lapse periods based on a corresponding plurality of input data sets, respectively, and a plurality of gamma function sets, wherein each ordered element of each set corresponds to a like-ordered image display area, respectively.

An exemplary embodiment display timing controller further includes a temporal smoother configured to provide a plurality of temporally smoothed data sets, each temporally smoothed data set to be displayed between successive output data sets corresponding to successive time lapse periods, respectively.

In an exemplary embodiment display timing controller, each of the plurality of temporally smoothed data sets is based on at least an immediately preceding output data set and an immediately succeeding output data set.

In an exemplary embodiment display timing controller, each of the plurality of gamma function sets comprises different gamma functions corresponding to different display areas, respectively, for at least one time lapse period.

In an exemplary embodiment display timing controller, each of the plurality of gamma function sets comprises different gamma functions for a periodically repeating subset of the plurality of time lapse periods, respectively.

In an exemplary embodiment display timing controller, each of the plurality of gamma function sets comprises different gamma functions corresponding to different display areas, respectively, and each pair of the plurality of gamma function sets comprises same-ordered different gamma functions corresponding to different time lapse periods, respectively.

In an exemplary embodiment display timing controller, at least one gamma function of each of the plurality of gamma function sets is implemented with a stored gamma lookup table.

In an exemplary embodiment display timing controller, the same-ordered gamma functions of the plurality of gamma function sets corresponding to a same-ordered display area indicate a plurality of different luminances corresponding to periodically repeating pluralities of time lapse periods, respectively.

In an exemplary embodiment display timing controller, each of a first plurality of gamma function sets is periodically applied once per first plurality of time lapse periods, wherein a next of the first plurality of gamma function sets is periodically applied in the next of the first plurality of time lapse periods with a luminance different from the preceding gamma function set.

In an exemplary embodiment display timing controller, the gamma compensator is configured to use a temporal local digital asymmetric gamma (L-DAG) driving scheme to select one of the plurality of gamma function sets during at least one of the plurality of time lapse periods depending on both a location of the display region and a lapse of driving time.

In an exemplary embodiment display timing controller, the gamma compensator compensates gamma variations depending on a location of a display region, the compensated gamma variations decrease a residual DC voltage in a display panel before the residual DC voltage is saturated, and an afterimage is substantially prevented.

Thus, the display apparatus according to the present inventive concept may operate based on the temporal local digital asymmetric gamma (L-DAG) driving scheme where different gamma lookup tables are used depending on both a location of the display region and a lapse of driving time. Accordingly, gamma variations depending on the location of the display region may be reduced, the residual DC voltage in the display panel may decrease before the residual DC voltage is saturated, and an afterimage or an image sticking in the display panel may be reduced.

DETAILED DESCRIPTION

The present inventive concept will be described more fully with reference to the accompanying drawings, in which exemplary embodiments are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Like reference numerals may refer to like elements throughout this application.

FIG. 1is a block diagram illustrating a display apparatus according to an exemplary embodiment.FIG. 2is a diagram illustrating a display panel included in the display apparatus according to an exemplary embodiment.

Referring toFIGS. 1 and 2, a display apparatus10includes a display panel100, a timing controller200, a gate driver300connected between the timing controller and the display panel, and a data driver400connected between the timing controller and the display panel.

The display panel100operates (e.g., displays an image) based on output image data DAT. The display panel100is connected to a plurality of gate lines GL from the gate driver and a plurality of data lines DL from the data driver. The gate lines GL may extend in a first direction D1, and the data lines DL may extend in a second direction D2crossing (e.g., substantially perpendicular to) the first direction D1. The display panel100may include a plurality of pixels (not illustrated) that are arranged in a matrix form. Each pixel may be electrically connected to a respective one of the gate lines GL and a respective one of the data lines DL.

In an exemplary embodiment, the display panel100may be divided into a plurality of display regions. For example, as illustrated inFIG. 2, the display panel100may include a first display region DA1and a second display region DA2. For another example, although not illustrated inFIG. 2, the display panel100may include M*N display regions where each of M and N is a natural number.

The timing controller200controls an operation of the display panel100and controls operations of the gate driver300and the data driver400. The timing controller200receives input image data IDAT and an input control signal ICONT from an external device (e.g., a host or a graphics processor). The input image data IDAT may include a plurality of input pixel data for the plurality of pixels. The input control signal ICONT may include a master clock signal, a data enable signal, a vertical synchronization signal, a horizontal synchronization signal, etc.

The timing controller200generates the output image data DAT based on the input image data IDAT. The timing controller200generates a first control signal CONT1based on the input control signal ICONT. The first control signal CONT1may be provided to the gate driver300, and a driving timing of the gate driver300may be controlled based on the first control signal CONT1. The first control signal CONT1may include a vertical start signal, a gate clock signal, etc. The timing controller200generates a second control signal CONT2based on the input control signal ICONT. The second control signal CONT2may be provided to the data driver400, and a driving timing of the data driver400may be controlled based on the second control signal CONT2. The second control signal CONT2may include a horizontal start signal, a data clock signal, a data load signal, a polarity control signal, etc.

The gate driver300generates a plurality of gate signals for driving the gate lines GL based on the first control signal CONT1. The gate driver300may sequentially apply the gate signals to the gate lines GL. For example, the gate driver300may include a plurality of shift registers (not illustrated).

The data driver400generates a plurality of analog data voltages based on the second control signal CONT2and the digital output image data DAT. The data driver400may sequentially apply the data voltages to the data lines DL. For example, the data driver400may include a shift register (not illustrated), a latch (not illustrated), a signal processor (not illustrated) and a buffer (not illustrated).

In an exemplary embodiment, the gate driver300and/or the data driver400may be disposed, such as directly mounted, on the display panel100, or may be connected to the display panel100in a tape carrier package (TCP) type. Alternatively, the gate driver300and/or the data driver400may be integrated on the display panel100.

The display apparatus10according to an exemplary embodiment may operate based on a local digital asymmetric gamma (L-DAG) driving scheme where different gamma lookup tables are used for different display regions among the plurality of display regions in the display panel100. In addition, in the display apparatus10according to an exemplary embodiment, different gamma lookup tables may be used for a single display region at different times or by a lapse of driving time. The present inventive concept is not limited to the use of lookup tables to implement gamma functions, as some gamma functions may be implemented algebraically, for example, but without limitation. A hybrid driving scheme where different gamma functions or gamma lookup tables are used in the display apparatus10depending on both a location of the display region and a lapse of driving time may be referred to herein as a temporal L-DAG driving scheme.

Hereinafter, the temporal L-DAG driving scheme according to an exemplary embodiment will be described based on an example where the display panel100includes at least two display regions DA1and DA2.

FIG. 3is a block diagram illustrating a timing controller included in the display apparatus according to an exemplary embodiment.

Referring toFIGS. 2 and 3, a timing controller200may include an image processor210, storage220connected to the image processor, and a control signal generator230. The timing controller200is illustrated inFIG. 3as being physically divided into multiple elements for convenience of explanation, however, the timing controller200need not be physically divided.

The image processor210includes a gamma compensator212, which may be connected to a temporal smoother214. The gamma compensator212may generate a plurality of output image data DO11, DO12, DO21, DO22, DO31, DO32, DO41and DO42based on a plurality of input image data DI11, DI12, DI21, DI22, DI31, DI32, DI41and DI42and a plurality of gamma lookup tables L11, L12, L21and L22. The temporal smoother214may generate a plurality of smoothing image data SD11, SD12, SD21, SD22, SD31, SD32, SD41and SD42based on the plurality of output image data DO11˜DO42.

The input image data DI11, DI21, DI31and DI41, the output image data DO11, DO21, DO31and DO41, and the smoothing image data SD11, SD21, SD31and SD41may be data for displaying an image (e.g., a first partial image) on the first display region DA1of the display panel100. The input image data DI12, DI22, DI32and DI42, the output image data DO12, DO22, DO32and DO42, and the smoothing image data SD12, SD22, SD32and SD42may be data for displaying an image (e.g., a second partial image) on the second display region DA2of the display panel100.

The plurality of input image data DI11˜DI42may be divided into four input image data sets IS1, IS2, IS3and IS4. The first input image data set IS1may include the first input image data DM and the second input image data DI12. The second input image data set IS2may include the third input image data DI21and the fourth input image data DI22. The third input image data set IS3may include the fifth input image data DI31and the sixth input image data DI32. The fourth input image data set IS4may include the seventh input image data DI41and the eighth input image data DI42.

Similarly, the plurality of output image data DO11˜DO42and the plurality of smoothing image data SD11˜SD42may be divided into four output image data sets OS1, OS2, OS3and OS4and four smoothing image data sets TSS1, TSS2, TSS3and TSS4, respectively. The first output image data set OS1may include the first output image data DO11and the second output image data DO12. The second output image data set OS2may include the third output image data DO21and the fourth output image data DO22. The third output image data set OS3may include the fifth output image data DO31and the sixth output image data DO32. The fourth output image data set OS4may include the seventh output image data DO41and the eighth output image data DO42. The first smoothing image data set TSS1may include the first smoothing image data SD11and the second smoothing image data SD12. The second smoothing image data set TSS2may include the third smoothing image data SD21and the fourth smoothing image data SD22. The third smoothing image data set TSS3may include the fifth smoothing image data SD31and the sixth smoothing image data SD32. The fourth smoothing image data set TSS4may include the seventh smoothing image data SD41and the eighth smoothing image data SD42.

Each of the input image data sets IS1˜IS4and each of the output image data sets OS1˜OS4may be data for displaying an image on the display panel100during a respective one driving duration. For example, the first input image data set IS1and the first output image data set OS1may be data for displaying an image (e.g., at least one frame) on the display panel100during a first driving duration (e.g., DP1inFIG. 5). The second input image data set IS2and the second output image data set OS2may be data for displaying an image on the display panel100during a second driving duration (e.g., DP2inFIG. 5) subsequent to the first driving duration. The third input image data set IS3and the third output image data set OS3may be data for displaying an image on the display panel100during a third driving duration (e.g., DP3inFIG. 5) subsequent to the second driving duration. The fourth input image data set IS4and the fourth output image data set OS4may be data for displaying an image on the display panel100during a fourth driving duration (e.g., DP4inFIG. 5) subsequent to the third driving duration.

Each of the smoothing image data sets TSS1˜TSS4may be data for reducing discontinuity between two consecutive images during a respective one smoothing duration. For example, the first smoothing image data set TSS1may be data for reducing discontinuity between the first output image data set OS1and the second output image data set OS2during a first smoothing duration (e.g., SP1inFIG. 5) between the first driving duration and the second driving duration. The second smoothing image data set TSS2may be data for reducing discontinuity between the second output image data set OS2and the third output image data set OS3during a second smoothing duration (e.g., SP2inFIG. 5) between the second driving duration and the third driving duration. The third smoothing image data set TSS3may be data for reducing discontinuity between the third output image data set OS3and the fourth output image data set OS4during a third smoothing duration (e.g., SP3inFIG. 5) between the third driving duration and the fourth driving duration. The fourth smoothing image data set TSS4may be data for reducing discontinuity between the fourth output image data set OS4and fifth output image data set corresponding to a fifth driving duration during a fourth smoothing duration (e.g., SP4inFIG. 5) between the fourth driving duration and the fifth driving duration.

Although not illustrated inFIG. 3, the image processor210may further include an element that selectively performs an image quality compensation, a spot compensation, an adaptive color correction (ACC), and/or a dynamic capacitance compensation (DCC) on the plurality of input image data DI11˜DI42.

The storage220may store the plurality of gamma lookup tables L11˜L22. In an exemplary embodiment, the storage220may include, for example, at least one nonvolatile memory such as an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a flash memory, a phase change random access memory (PRAM), a resistance random access memory (RRAM), a magnetic random access memory (MRAM), a ferroelectric random access memory (FRAM), a nano floating gate memory (NFGM), a polymer random access memory (PoRAM), etc. In an exemplary embodiment, the storage220may be disposed outside the timing controller200.

The first and third gamma lookup tables L11and L21may correspond to the first display region DA1of the display panel100. The second and fourth gamma lookup tables L12and L22may correspond to the second display region DA2of the display panel100. In other words, the first and third gamma lookup tables L11and L21may be used for displaying the image on the first display region DA1of the display panel100, and the second and fourth gamma lookup tables L12and L22may be used for displaying the image on the second display region DA2of the display panel100.

The plurality of gamma lookup tables L11˜L22may be divided into two gamma lookup table sets LS1and LS2. The first gamma lookup table set LS1may include the first and second gamma lookup tables L11and L12. The second gamma lookup table set LS2may include the third and fourth gamma lookup tables L21and L22.

In an exemplary embodiment, the first gamma lookup table L11may include gamma data different from that of the second gamma lookup table L12. The gamma data of the first gamma lookup table L11may also be different from that of the third gamma lookup table L21. Similarly, the third gamma lookup table L21may include gamma data different from that of the fourth gamma lookup table L22.

The control signal generator230may receive the input control signal ICONT. The control signal generator230may generate the first control signal CONT1for the gate driver300and the second control signal CONT2for the data driver400based on the input control signal ICONT. The control signal generator230may output the first control signal CONT1to the gate driver300and may output the second control signal CONT2to the data driver400.

FIGS. 4, 5 and 6are diagrams for describing an operation of the display apparatus according to an exemplary embodiment.FIG. 4is a graph illustrating an example of the gamma lookup tables stored in the storage220inFIG. 3.FIG. 5is a diagram illustrating an example of the temporal L-DAG driving scheme based on the gamma lookup tables inFIG. 4.FIG. 6is a diagram illustrating a change of a residual direct current (DC) voltage in the display panel100when the display apparatus10operates based on the temporal L-DAG driving scheme inFIG. 5.

Referring toFIGS. 3 and 4, a level of a gamma voltage generated based on the first gamma lookup table L11may be higher than a level of a gamma voltage generated based on the third gamma lookup table L21. In other words, a luminance of an image based on the first gamma lookup table L11may be higher than a luminance of an image based on the third gamma lookup table L21, and the gamma data of the first gamma lookup table L11may be greater than the gamma data of the third gamma lookup table L21. The present inventive concept is not limited to a preceding image being brighter than a succeeding image, as the brighter image may come later, or more than two images of differing luminances based on more than two gamma function sets may be displayed in sequence, for example, without limitation.

Although not illustrated inFIG. 4, a relationship between the second gamma lookup table L12and the fourth gamma lookup table L22may be substantially the same as a relationship between the first gamma lookup table L11and the third gamma lookup table L21. In other words, a luminance of an image based on the second gamma lookup table L12may be higher than a luminance of an image based on the fourth gamma lookup table L22.

Referring toFIGS. 2, 3, 5 and 6, the image processor210may perform image processing for the temporal L-DAG driving scheme, and the display panel100may operate (e.g., may display an image) based on image data outputted from the image processor210.

First of all, an operation of the display apparatus10for the first display region DA1of the display panel100will be described in detail.

The first output image data DO11for a first driving duration DP1and the fifth output image data DO31for a third driving duration DP3may be generated based on the first gamma lookup table L11. The third output image data DO21for a second driving duration DP2and the seventh output image data DO41for a fourth driving duration DP4may be generated based on the third gamma lookup table L21.

For example, the gamma compensator212may generate the first output image data DO11based on the first input image data DI11and the first gamma lookup table L11, may generate the third output image data DO21based on the third input image data DI21and the third gamma lookup table L21, may generate the fifth output image data DO31based on the fifth input image data DI31and the first gamma lookup table L11, and may generate the seventh output image data DO41based on the seventh input image data DI41and the third gamma lookup table L21.

The first display region DA1of the display panel100may operate based on the first output image data DO11, the third output image data DO21, the fifth output image data DO31and the seventh output image data DO41. For example, the display panel100may display an image on the first display region DA1based on the first output image data DO11during the first driving duration DP1, may display an image on the first display region DA1based on the third output image data DO21during the second driving duration DP2, may display an image on the first display region DA1based on the fifth output image data DO31during the third driving duration DP3, and may display an image on the first display region DA1based on the seventh output image data DO41during the fourth driving duration DP4.

A temporal smoothing operation for the first display region DA1may be performed to reduce discontinuity between two consecutive output image data during a smoothing duration (e.g., one of SP1, SP2, SP3and SP4) between two consecutive driving durations.

For example, the temporal smoother214may generate the first smoothing image data SD11by performing an interpolation based on the first output image data DO11and the third output image data DO21, may generate the third smoothing image data SD21by performing the interpolation based on the third output image data DO21and the fifth output image data DO31, and may generate the fifth smoothing image data SD31by performing the interpolation based on the fifth output image data DO31and the seventh output image data DO41. In addition, the temporal smoother214may generate the seventh smoothing image data SD41by performing the interpolation based on the seventh output image data DO41and ninth output image data corresponding to the first display region DA1and a fifth driving duration subsequent to the fourth driving duration DP4.

Each of the smoothing image data SD11, SD21, SD31and SD41may have at least one value for preventing a drastic change of the output image data (e.g., for a buffering function). For example, the first smoothing image data SD11may have a middle value of the first output image data DO11and the third output image data DO21. For another example, the first smoothing image data SD11may have a first value that is between the first output image data DO11and the third output image data DO21, and a second value that is greater than the first value and is between the first output image data DO11and the third output image data DO21.

The first display region DA1of the display panel100may operate based on the first smoothing image data SD11, the third smoothing image data SD21, the fifth smoothing image data SD31and the seventh smoothing image data SD41. For example, the display panel100may display an image on the first display region DA1based on the first smoothing image data SD11during a first smoothing duration SP1, may display an image on the first display region DA1based on the third smoothing image data SD21during a second smoothing duration SP2, may display an image on the first display region DA1based on the fifth smoothing image data SD31during a third smoothing duration SP3, and may display an image on the first display region DA1based on the seventh smoothing image data SD41during a fourth smoothing duration SP4.

InFIG. 6, CASE1may represent an example of a conventional display apparatus where a gamma lookup table for operating a display panel is fixed, and CASE2may represent an example of the display apparatus10according to an exemplary embodiment where the gamma lookup tables for operating the display panel100are changed by a lapse of time. In CASE1, a residual DC voltage in the display panel may continuously or asymptotically increase by a lapse of time. However, in CASE2, a residual DC voltage in the display panel100(e.g., in the first display region DA1) may increase or may decrease by a lapse of time. For example, the residual DC voltage in the display panel100may increase from time0to time t1(or from time t2to time t3), during which the first gamma lookup table L11having a relatively great value is used for operating the display panel100. The residual DC voltage in the display panel100may decrease from time t1to time t2(or from time t3to time t4), during which the third gamma lookup table L21having a relatively small value is used for operating the display panel100.

Next, an operation of the display apparatus10for the second display region DA2of the display panel100will be described in detail.

According to an exemplary embodiment, the temporal L-DAG driving scheme may be entirely or partially employed on the display panel100. In other words, the operation of the display apparatus10for the second display region DA2of the display panel100may be substantially the same as or different from the operation of the display apparatus10for the first display region DA1of the display panel100.

The second output image data DO12for the first driving duration DP1and the sixth output image data DO32for the third driving duration DP3may be generated based on the second gamma lookup table L12. The fourth output image data DO22for the second driving duration DP2and the eighth output image data DO42for the fourth driving duration DP4may be generated based on one of the second gamma lookup table L12and the fourth gamma lookup table L22.

For example, the gamma compensator212may generate the second output image data DO12based on the second input image data DI12and the second gamma lookup table L12, and may generate the sixth output image data DO32based on the sixth input image data DI32and the second gamma lookup table L12. The gamma compensator212may generate the fourth output image data DO22based on the fourth input image data DI22and one of the second and fourth gamma lookup tables L12and L22, and may generate the eighth output image data DO42based on the eighth input image data DI42and one of the second and fourth gamma lookup tables L12and L22.

The display panel100may display an image on the second display region DA2based on the second output image data DO12during the first driving duration DP1, based on the fourth output image data DO22during the second driving duration DP2, based on the sixth output image data DO32during the third driving duration DP3, and based on the eighth output image data DO42during the fourth driving duration DP4.

A temporal smoothing operation for the second display region DA2may be performed to reduce discontinuity between two consecutive output image data during the smoothing duration.

For example, the temporal smoother214may generate the second smoothing image data SD12by performing the interpolation based on the second output image data DO12and the fourth output image data DO22, may generate the fourth smoothing image data SD22by performing the interpolation based on the fourth output image data DO22and the sixth output image data DO32, and may generate the sixth smoothing image data SD32by performing the interpolation based on the sixth output image data DO32and the eighth output image data DO42. In addition, the temporal smoother214may generate the eighth smoothing image data SD42by performing the interpolation based on the eighth output image data DO42and tenth output image data corresponding to the second display region DA2and the fifth driving duration.

The display panel100may display an image on the second display region DA2based on the second smoothing image data SD12during the first smoothing duration SP1, based on the fourth smoothing image data SD22during the second smoothing duration SP2, based on the sixth smoothing image data SD32during the third smoothing duration SP3, and based on the eighth smoothing image data SD42during the fourth smoothing duration SP4.

In an exemplary embodiment, at least a part of the temporal smoothing operation may be omitted. For example, when the temporal L-DAG driving scheme is partially employed on the display panel100(e.g., on the first display region DA1), the temporal smoothing operation for the second display region DA2may be omitted. For example, when the fourth output image data DO22is generated based on the second gamma lookup table L12, e.g., when all of the output image data DO12, DO22and DO32for the driving durations DP1, DP2and DP3are generated based on the second gamma lookup table L12, the temporal smoothing operation for the second display region DA2may be omitted during the first and second smoothing durations SP1and SP2.

In an exemplary embodiment, a spatial smoothing operation may be further performed to reduce discontinuity in a boundary region between the first display region DA1and the second display region DA2. For example, the image processor210may further perform the spatial smoothing operation to reduce discontinuity between the first output image data DO11and the second output image data DO12during the first driving duration DP1. Similarly, the image processor210may further perform the spatial smoothing operation to reduce discontinuity between each of the output image data DO21, DO31and DO41and a respective one of the output image data DO22, DO32and DO42during the driving durations DP2, DP3and DP4, and may further perform the spatial smoothing operation to reduce discontinuity between each of the smoothing image data SD11, SD21, SD31and SD41and a respective one of the smoothing image data SD12, SD22, SD32and SD42during the smoothing durations SP1, SP2, SP3and SP4.

In an exemplary embodiment, each of the driving durations DP1, DP2, DP3and DP4and each of the smoothing durations SP1, SP2, SP3and SP4may include at least one frame that indicates a time required to display one image frame on the display panel100.

The display apparatus10according to an exemplary embodiment may operate based on the temporal L-DAG driving scheme where different gamma lookup tables are used depending on both a location of the display region and a lapse of driving time. Accordingly, gamma variations depending on the location of the display region may be reduced, the residual DC voltage in the display panel100may decrease before the residual DC voltage is saturated, and thus an afterimage or an image sticking in the display panel100may be reduced.

FIG. 7is a block diagram illustrating a timing controller included in the display apparatus according to an exemplary embodiment.

Referring toFIGS. 2 and 7, a timing controller200amay include an image processor210, storage220aand a control signal generator230.

The timing controller200aofFIG. 7may be substantially the same as the timing controller200ofFIG. 2, except that gamma lookup tables stored in the storage220aare changed, and then image data generated by the image processor210are changed.

The image processor210may include a gamma compensator212and a temporal smoother214. The gamma compensator212may generate a plurality of output image data DO11′, DO12′, DO21′, DO22′, DO31′, DO32′, DO41′ and DO42′ based on a plurality of input image data DI11, DI12, DI21, DI22, DI31, DI32, DI41and DI42and a plurality of gamma lookup tables LA1, LA2, LB1, LB2, LC1and LC2. The temporal smoother214may generate a plurality of smoothing image data SD11′, SD12′, SD21′, SD22′, SD31′, SD32′, SD41′ and SD42′ based on the plurality of output image data DO11′˜DO42′.

The input image data DI11, DI21, DI31and DI41, the output image data DO11′, DO21′, DO31′ and DO41′, and the smoothing image data SD11′, SD21′, SD31′ and SD41′ may be data for displaying an image on the first display region DA1of the display panel100. The input image data DI12, DI22, DI32and DI42, the output image data DO12′, DO22′, DO32′ and DO42′, and the smoothing image data SD12′, SD22′, SD32′ and SD42′ may be data for displaying an image on the second display region DA2of the display panel100.

The plurality of input image data DI11˜DI42may be divided into four input image data sets IS1, IS2, IS3and IS4. Similarly, the plurality of output image data DO11′˜DO42′ and the plurality of smoothing image data SD11′˜SD42′ may be divided into four output image data sets OS1′, OS2′, OS3′ and OS4′ and four smoothing image data sets TSS1′, TSS2′, TSS3′ and TSS4′, respectively. Each of the input image data sets IS1˜IS4and each of the output image data sets OS1′˜OS4′ may be data for displaying an image on the display panel100during a respective one driving duration (e.g., DPA, DPB, DPC and DPD inFIG. 9). Each of the smoothing image data sets TSS1′˜TSS4′ may be data for reducing discontinuity between two consecutive images during a respective one smoothing duration (e.g., SPA, SPB, SPC and SPD inFIG. 9).

The storage220may store the plurality of gamma lookup tables LA1˜LC2. The first, third and fifth gamma lookup tables LA1, LB1and LC1may correspond to the first display region DA1of the display panel100. The second, fourth and sixth gamma lookup tables LA2, LB2and LC2may correspond to the second display region DA2of the display panel100. The plurality of gamma lookup tables LA1˜LC2may be divided into three gamma lookup table sets LSA, LSB and LSC. The first gamma lookup table LA1may include gamma data different from that of the second gamma lookup table LA2and also different from those of the third and fifth gamma lookup tables LB1and LC1.

FIGS. 8 and 9are diagrams for describing an operation of the display apparatus according to an exemplary embodiment.FIG. 8is a graph illustrating an example of the gamma lookup tables stored in the storage220ainFIG. 7.FIG. 9is a diagram illustrating an example of the temporal L-DAG driving scheme based on the gamma lookup tables inFIG. 8.

Referring toFIGS. 7 and 8, a level of a gamma voltage generated based on the first gamma lookup table LA1may be lower than a level of a gamma voltage generated based on the third gamma lookup table LB1, and may be higher than a level of a gamma voltage generated based on the fifth gamma lookup table LC1. In other words, a luminance of an image based on the first gamma lookup table LA1may be lower than a luminance of an image based on the third gamma lookup table LB1, and may be higher than a luminance of an image based on the fifth gamma lookup table LC1. Although not illustrated inFIG. 8, a relationship between the gamma lookup tables LA2, LB2and LC2may be substantially the same as a relationship between the gamma lookup tables LA1, LB1and LC1.

Referring toFIGS. 2, 7 and 9, the image processor210may perform an image processing for the temporal L-DAG driving scheme, and the display panel100may operate based on image data outputted from the image processor210.

In an operation of the display apparatus10for the first display region DA1of the display panel100, the gamma compensator212may generate the first output image data DO11′ based on the first input image data DM and the first gamma lookup table LA1, may generate the third output image data DO21′ based on the third input image data DI21and the third gamma lookup table LB1, may generate the fifth output image data DO31′ based on the fifth input image data DI31and the first gamma lookup table LA1, and may generate the seventh output image data DO41′ based on the seventh input image data DI41and the fifth gamma lookup table LC1.

The display panel100may display an image on the first display region DA1based on the first output image data DO11′ during a first driving duration DPA, based on the third output image data DO21′ during a second driving duration DPB, based on the fifth output image data DO31′ during a third driving duration DPC, and based on the seventh output image data DO41′ during a fourth driving duration DPD.

The temporal smoothing operation for the first display region DA1may be performed to reduce discontinuity between two consecutive output image data during the smoothing duration. For example, the temporal smoother214may generate the first smoothing image data SD11′ by performing the interpolation based on the first output image data DO11′ and the third output image data DO21′, may generate the third smoothing image data SD21′ by performing the interpolation based on the third output image data DO21′ and the fifth output image data DO31′, may generate the fifth smoothing image data SD31′ by performing the interpolation based on the fifth output image data DO31′ and the seventh output image data DO41′, and may generate the seventh smoothing image data SD41′ by performing the interpolation based on the seventh output image data DO41′ and ninth output image data corresponding to the first display region DA1and a fifth driving duration subsequent to the fourth driving duration DPD.

The display panel100may display an image on the first display region DA1based on the first smoothing image data SD11′ during a first smoothing duration SPA, based on the third smoothing image data SD21′ during a second smoothing duration SPB, based on the fifth smoothing image data SD31′ during a third smoothing duration SPC, and based on the seventh smoothing image data SD41′ during a fourth smoothing duration SPD.

In an operation of the display apparatus10for the second display region DA2of the display panel100, the temporal L-DAG driving scheme may be entirely or partially employed on the display panel100. In other words, the operation of the display apparatus10for the second display region DA2of the display panel100may be substantially the same as or different from the operation of the display apparatus10for the first display region DA1of the display panel100. According to an exemplary embodiment, the temporal smoothing operation for the second display region DA2may be selectively performed, and the spatial smoothing operation may be further performed to reduce discontinuity in a boundary region between the first display region DA1and the second display region DA2.

FIGS. 10 and 11are block diagrams illustrating a timing controller included in the display apparatus according to an exemplary embodiment.

Referring toFIG. 10, a timing controller200bmay include an image processor210, storage220, a control signal generator230and a period controller240b. Referring toFIG. 11, a timing controller200cmay include an image processor210, storage220, a control signal generator230, a period controller240cand a determinator250c.

The timing controller200bofFIG. 10may be substantially the same as the timing controller200ofFIG. 2, except that the timing controller200bfurther includes the period controller240b. The timing controller200cofFIG. 11may be substantially the same as the timing controller200ofFIG. 2, except that the timing controller200cfurther includes the period controller240cand the determinator250c.

In the display apparatus10according to an exemplary embodiment, a length of at least one of the driving durations (e.g., DP1, DP2, DP3and DP4inFIG. 5) and/or a length of at least one of the smoothing durations (e.g., SP1, SP2, SP3and SP4inFIG. 5) may be variable.

The timing controller200bofFIG. 10may change the length of the at least one of the driving durations and/or the length of the at least one of the smoothing durations based on a flag signal FLG that is received from an external device (e.g., a host or a graphic processor).

The period controller240binFIG. 10may generate a period control signal PCON based on the flag signal FLG that indicates a type of an image displayed on the display panel100.

The timing controller200cofFIG. 11may determine a type of an image displayed on the display panel100based on the input image data DI11˜DI42, and may change the length of the at least one of the driving durations and/or the length of the at least one of the smoothing durations based on the type of the image.

The determinator250cinFIG. 11may generate a determination signal DET indicating the type of the image based on the input image data DI11˜DI42. For example, the determinator250cmay compare image data for a previous frame with image data for a present frame to determine the type of the image, and may include a frame memory and/or a line memory. The period controller240cinFIG. 11may generate a period control signal PCON based on the determination signal DET.

In the examples ofFIGS. 10 and 11, the period control signal PCON may be provided to the image processor210and the storage220. The length of the at least one of the driving durations and/or the length of the at least one of the smoothing durations may be changed based on the period control signal PCON.

In an exemplary embodiment, when a static image (e.g., a still image, a stopped image, a photograph, etc.) is displayed on the display panel100, the timing controller200bor the timing controller200cmay decrease the length of the at least one of the driving durations and/or the length of the at least one of the smoothing durations may be changed based on the period control signal PCON. When a dynamic image (e.g., a moving image, a video, etc.) is displayed on the display panel100, the timing controller200bor the timing controller200cmay increase the length of the at least one of the driving durations and/or the length of the at least one of the smoothing durations may be changed based on the period control signal PCON.

In an exemplary embodiment, when the static image is displayed on the display panel100, the timing controller200bor the timing controller200cmay maintain the temporal L-DAG driving scheme based on the period control signal PCON. When a dynamic image (e.g., a moving image, a video, etc.) is displayed on the display panel100, the timing controller200bor the timing controller200cmay stop performing the temporal L-DAG driving scheme based on the period control signal PCON.

FIG. 12is a block diagram illustrating a display apparatus according to an exemplary embodiment.

Referring toFIG. 12, a display apparatus20includes a display panel100, a timing controller600, a gate driver300and a data driver400. The display apparatus20may further include a gamma voltage generator500.

The display apparatus20ofFIG. 12may be substantially the same as the display apparatus10ofFIG. 1, except that the display apparatus20ofFIG. 12further includes the gamma voltage generator500. In addition, the timing controller600inFIG. 12may be partially different from the timing controller200inFIG. 1.

The timing controller600controls an operation of the display panel100and controls operations of the gate driver300, the data driver400and the gamma voltage generator500. The timing controller600generates output image data DAT, a first control signal CONT1, a second control signal CONT2and a third control signal CONT3based on input image data IDAT and an input control signal ICONT.

The gamma voltage generator500receives the third control signal CONT3from the timing controller600. The gamma voltage generator500generates gamma reference voltages VG based on the third control signal CONT3. To employ the temporal L-DAG driving scheme, different gamma lookup tables may be used for generating the gamma reference voltages VG depending on both a location of the display region and a lapse of driving time. The gamma lookup tables may be stored in the timing controller600, the gamma voltage generator500, and/or any storage (not illustrated).

FIG. 13is a flow chart illustrating a method of operating a display apparatus according to an exemplary embodiment.

Referring toFIGS. 1, 2, 3 and 13, in the method of operating the display apparatus according to an exemplary embodiment, the output image data DO11is generated based on the input image data DI11and the gamma lookup table L11(step S100). The output image data DO21is generated based on the input image data DI21and the gamma lookup table L21(step S200). The display panel100operates based on the output image data DO11during the driving duration DP1(step S300), and operates based on the output image data DO21during the driving duration DP2subsequent to the driving duration DP1(step S500). Thus, an image is displayed on the first display region DA1of the display panel100.

In an exemplary embodiment, the temporal smoothing operation may be performed to reduce discontinuity between the output image data DO11and the output image data DO21during the smoothing duration SP1between the driving duration DP1and the driving duration DP2(step S400). For example, the smoothing image data SD11may be generated by performing the interpolation based on the output image data DO11and the output image data DO21, and the display panel100may operate based on the smoothing image data SD11during the smoothing duration SP1.

In an exemplary embodiment, based on the example described above with reference toFIGS. 3, 4 and 5, the plurality of image data DO11˜DO42and SD11˜SD42may be generated, and the display panel100may display the image on the first display region DA1. In an exemplary embodiment, based on the example described above with reference toFIGS. 7, 8 and 9, the plurality of image data DO11′˜DO42′ and SD11′˜SD42′ may be generated, and the display panel100may display the image on the first display region DA1. In addition, in the operation of the display apparatus10for the second display region DA2of the display panel100, the temporal L-DAG driving scheme may be entirely or partially employed on the display panel100.

Although exemplary embodiments are described based on examples where the display panel includes two display regions and each display region operates based on two or more gamma lookup tables, the temporal L-DAG driving scheme according to an exemplary embodiments may be employed where a display panel includes any number of display regions and each display region operates based on any number of gamma lookup tables. In addition, although exemplary embodiments are described where the display apparatus operates during four driving durations (e.g., inFIGS. 5 and 9), the temporal L-DAG driving scheme may be employed where a display apparatus operates during any number of driving durations. For example, the example inFIG. 5and/or the example inFIG. 9may be repeated for each of four driving durations.

The above described embodiments may be used in a display apparatus and/or a system including the display apparatus, such as a mobile phone, a smart phone, a personal digital assistant (PDA), a portable multimedia player (PMP), a digital camera, a digital television, a set-top box, a music player, a portable game console, a navigation device, a personal computer (PC), a server computer, a workstation, a tablet computer, a laptop computer, a smart card, a printer, or the like.