Display apparatus and method of driving the same

A display apparatus includes: a display panel comprising a plurality of pixels configured to display an image based on input image data; a gate driver configured to output a gate signal to the display panel; a data driver configured to output a data voltage to the display panel; a light source part configured to provide light to the display panel and comprising a plurality of light sources; and a light source driver configured to drive the light source part, wherein a first light source of the light source part is configured to output a first luminance in an active period defined by the data voltage being output to the pixel and a second luminance greater than the first luminance in an inactive period defined by the data voltage is not being output to the pixel.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0044742, filed on Apr. 17, 2019 in the Korean Intellectual Property Office KIPO, the contents of which are herein incorporated by reference in their entireties.

BACKGROUND

Aspects of some example embodiments of the present inventive concept relate to a display apparatus and a method of driving the display apparatus.

2. Description of the Related Art

Generally, a display apparatus includes a display panel and a display panel driver. The display panel displays an image based on input image data. The display panel includes a plurality of gate lines, a plurality of data lines and a plurality of pixels. The display panel driver includes a gate driver, a data driver and a driving controller. The gate driver outputs gate signals to the gate lines. The data driver outputs data voltages to the data lines. The driving controller controls the gate driver and the data driver.

The display apparatus may further include a light source part providing a light to the display panel and a light source driver driving the light source part.

The image may be displayed on the display panel in a variable frame rate. When the display panel is driven in a low frame rate, a luminance of the image may be reduced due to a leakage current of the pixels.

SUMMARY

Aspects of some example embodiments of the present inventive concept relate to a display apparatus and a method of driving the display apparatus. For example, some example embodiments of the present inventive concept relate to a display apparatus adjusting a luminance of a light source during a vertical blank period or a holding frame to enhance a display quality of the display apparatus and a method of driving the display apparatus.

Aspects of some example embodiments of the present inventive concept may include a display apparatus configured to adjust a luminance of a light source during a vertical blank period or a holding frame to enhance a display quality.

Aspects of some example embodiments of the present inventive concept may also include a method of driving the display apparatus.

According to some example embodiments of the present inventive concept, a display apparatus includes a display panel, a gate driver, a data driver, a light source part and a light source driver. The display panel includes a plurality of pixels and is configured to display an image based on input image data. The gate driver is configured to output a gate signal to the display panel. The data driver is configured to output a data voltage to the display panel. The light source part is configured to provide light to the display panel and includes a plurality of light sources. The light source driver is configured to drive the light source part. A first light source of the light source part is configured to output a first luminance in an active period when the data voltage is outputted to the pixel and a second luminance greater than the first luminance in an inactive period when the data voltage is not outputted to the pixel.

According to some example embodiments, the display panel may be driven in a frame rate which is variable. When the frame rate is greater than a threshold frame rate, the first light source may be configured to output the first luminance in the active period and the inactive period. When the frame rate is equal to or less than the threshold frame rate, the first light source may be configured to output the first luminance in the active period and the second luminance in the inactive period.

According to some example embodiments, the second luminance may be determined according to the frame rate of the display panel and a grayscale value of the input image data.

According to some example embodiments, the display panel may be driven in a unit of a frame. The frame may include an active period and a vertical blank period. The frame rate of the display panel may be varied according to the input image data. The active period may have a uniform length regardless of the frame rate. As the frame rate decreases, a length of the vertical blank period may increase. The inactive period may be the vertical blank period.

According to some example embodiments, the display apparatus may further include a driving controller configured to control a driving timing of the gate driver and a driving timing of the data driver. When the input image data represents a video image, the driving controller may be configured to determine a frame rate of the display panel to a first frame rate. When the input image data represents a static image, the driving controller may be configured to determine the frame rate of the display panel to a second frame rate less than the first frame rate. The display panel may be driven only in a writing frame including the active period in the first frame rate. The display panel may be driven in the writing frame including the active period and a holding frame not including the active period in the second frame rate. The inactive period may be the holding frame.

According to some example embodiments, the driving controller may include a frequency determiner configured to determine whether the input image data represents a video image or a static image and determine the frame rate, a signal generator configured to generate a first control signal to control the gate driver and a second control signal to control the data driver based on an input control signal and the frame rate and a data compensator configured to generate a data signal based on the input image data and the frame rate.

According to some example embodiments, the light source driver may be configured to determine a duty ratio of a light source driving signal to a first duty ratio such that the first light source outputs the first luminance. The light source driver may be configured to determine the duty ratio of the light source driving signal to a second duty ratio greater than the first duty ratio such that the first light source outputs the second luminance.

According to some example embodiments, when the duty ratio of the light source driving signal is 100%, the light source driver may be configured to determine a light source driving current to a first current such that the first light source outputs the first luminance. When the duty ratio of the light source driving signal is 100%, the light source driver may be configured to determine the light source driving current to a second current greater than the first current such that the first light source outputs the second luminance.

According to some example embodiments, the light source part may include a plurality of mini LEDs. The mini LEDs may be configured to have independent luminances.

According to some example embodiments, the mini LEDs may be configured to have independent duty ratios of light source driving signals.

According to some example embodiments, outermost light sources of the light source part may be configured to output a luminance greater than a luminance of light sources which are not the outermost light sources.

According to some example embodiments, the first light source may be configured to output a gradually increasing luminance in the inactive period.

According to some example embodiments, in a method of driving a display apparatus, the method includes outputting a gate signal to a display panel comprising a plurality of pixels and configured to display an image based on input image data, outputting a data voltage to the display panel and providing light to the display panel using a light source part comprising a plurality of light sources. A first light source of the light source part is configured to output a first luminance in an active period when the data voltage is outputted to the pixel and a second luminance greater than the first luminance in an inactive period when the data voltage is not outputted to the pixel.

According to some example embodiments, the display panel may be driven in a frame rate which is variable. When the frame rate is greater than a threshold frame rate, the first light source may be configured to output the first luminance in the active period and the inactive period. When the frame rate is equal to or less than the threshold frame rate, the first light source may be configured to output the first luminance in the active period and the second luminance in the inactive period.

According to some example embodiments, the second luminance may be determined according to the frame rate of the display panel and a grayscale value of the input image data.

According to some example embodiments, the display panel may be driven in a unit of a frame. The frame may include an active period and a vertical blank period. The frame rate of the display panel may be varied according to the input image data. The active period may have a uniform length regardless of the frame rate. As the frame rate decreases, a length of the vertical blank period may increase. The inactive period may be the vertical blank period.

According to some example embodiments, the method may further include determining a frame rate of the display panel to a first frame rate when the input image data represents a video image and determining the frame rate of the display panel to a second frame rate less than the first frame rate when the input image data represents a static image. The display panel may be driven only in a writing frame including the active period in the first frame rate. The display panel may be driven in the writing frame including the active period and a holding frame not including the active period in the second frame rate. The inactive period may be the holding frame.

According to some example embodiments, a duty ratio of a light source driving signal may have a first duty ratio when the first light source outputs the first luminance. The duty ratio of the light source driving signal may have a second duty ratio greater than the first duty ratio when the first light source outputs the second luminance.

According to some example embodiments, when the duty ratio of the light source driving signal is 100% and the first light source outputs the first luminance, a light source driving current may have a first current. When the duty ratio of the light source driving signal is 100% and the first light source outputs the second luminance, the light source driving current may have a second current greater than the first current.

According to some example embodiments, the first light source may be configured to output a gradually increasing luminance in the inactive period.

According to the display apparatus and the method of driving the display apparatus, the luminance of the light source may be compensated during the vertical blank period or the holding frame to prevent the decrease of the luminance of the image due to the leakage current of the pixel in the low frame rate. Thus, the luminance of the image may be compensated so that the display quality of the display apparatus may be enhanced.

DETAILED DESCRIPTION

Hereinafter, aspects of some example embodiments of the present inventive concept will be explained in more detail with reference to the accompanying drawings.

FIG. 1is a block diagram illustrating a display apparatus according to some example embodiments of the present inventive concept.

Referring toFIG. 1, the display apparatus includes a display panel100and a display panel driver. The display panel driver includes a driving controller200, a gate driver300, a gamma reference voltage generator400, and a data driver500. The display apparatus may further include a light source part BLU providing light to the display panel100and a light source driver600driving the light source part BLU. The display apparatus may further include a host700providing input image data to the driving controller200.

For example, the driving controller200and the data driver500may be integrally formed. For example, the driving controller200, the gamma reference voltage generator400and the data driver500may be integrally formed. For example, the driving controller200, the gate driver300, the gamma reference voltage generator400and the data driver500may be integrally formed.

The display panel100includes a plurality of gate lines GL, a plurality of data lines DL and a plurality of pixels electrically connected to the gate lines GL and the data lines DL. The gate lines GL may extend in a first direction D1and the data lines DL may extend in a second direction D2crossing the first direction D1. According to some example embodiments, the display panel100may be a liquid crystal display panel including a liquid crystal layer.

The driving controller200may receive input image data IMG and an input control signal CONT from an external apparatus. For example, the input image data IMG may include red image data, green image data and blue image data. The input image data IMG may include white image data. The input image data IMG may include magenta image data, cyan image data and yellow image data. The input control signal CONT may include a master clock signal and a data enable signal. The input control signal CONT may further include a vertical synchronizing signal and a horizontal synchronizing signal.

The driving controller200generates the second control signal CONT2for controlling an operation of the data driver500based on the input control signal CONT, and outputs the second control signal CONT2to the data driver500. The second control signal CONT2may include a horizontal start signal and a load signal.

The driving controller200generates the data signal DATA based on the input image data IMG. The driving controller200outputs the data signal DATA to the data driver500.

The driving controller200generates the third control signal CONT3for controlling an operation of the gamma reference voltage generator400based on the input control signal CONT, and outputs the third control signal CONT3to the gamma reference voltage generator400.

The gate driver300generates gate signals driving the gate lines GL in response to the first control signal CONT1received from the driving controller200. The gate driver300may output the gate signals to the gate lines GL. For example, the gate driver300may be mounted on the display panel100. For example, the gate driver300may be integrated on the display panel100.

The gamma reference voltage generator400generates a gamma reference voltage VGREF in response to the third control signal CONT3received from the driving controller200. The gamma reference voltage generator400provides the gamma reference voltage VGREF to the data driver500. The gamma reference voltage VGREF has a value corresponding to a level of the data signal DATA.

According to some example embodiments, the gamma reference voltage generator400may be located in the driving controller200, or in the data driver500.

The data driver500receives the second control signal CONT2and the data signal DATA from the driving controller200, and receives the gamma reference voltages VGREF from the gamma reference voltage generator400. The data driver500converts the data signal DATA into data voltages having an analog type using the gamma reference voltages VGREF. The data driver500outputs the data voltages to the data lines DL.

The light source part BLU includes a plurality of light sources. The light source part BLU provides light to the display panel100. The light sources may be mini LEDs. For example, the mini LEDs may be independently driven. For example, the mini LEDs may have independent luminances.

The light source driver600may output a light source driving signal for driving the light source part BLU to the light source part BLU. The light source driver600may independently drive the light sources.

FIG. 2is a conceptual diagram illustrating frames when the display panel100ofFIG. 1displays an image.FIG. 3Ais a timing diagram illustrating a vertical start signal and a clock signal when a frame rate of the display panel100ofFIG. 1is a first frame rate.FIG. 3Bis a timing diagram illustrating a vertical start signal and a clock signal when the frame rate of the display panel100ofFIG. 1is a second frame rate.FIG. 3Cis a timing diagram illustrating a vertical start signal and a clock signal when the frame rate of the display panel100ofFIG. 1is a third frame rate.

Referring toFIGS. 1 to 3C, the display panel100may display the image in a unit of the frame. The frame may include an active period ACTIVE and a vertical blank period VBL. In the active period ACTIVE, the data voltage may be written to the pixel.

According to some example embodiments, the frame rate of the display panel100may be variable. For example, the input image data IMG may include information of the variable frame rate. Thus, the driving controller200may determine the frame rate of the display panel100according to the information of the variable frame rate included in the input image data IMG.

The active periods ACTIVE1to ACTIVE5may have a uniform length regardless of the frame rate. In contrast, lengths of the vertical blank periods VBL1to VBL5may be varied according to the frame rate. For example, as the frame rate decreases, the length of the vertical blank period VBL1to VBL5may increase.

InFIG. 3A, the frame rate of the display panel100may be a first frame rate. The length of the frame may be defined as a duration between adjacent pulses of a vertical start signal STV. The gate signal is generated in synchronous with a pulse of the clock signal CKV and the gate signal is outputted to the gate line. When the gate signal is outputted to the gate line, the data voltage is charged to the pixel. The active period may be defined as a duration when the pulses of the clock signal CKV are outputted. The active period may be also defined as a duration when the data voltages are outputted to the pixels. An inactive period may be defined as a duration when the data voltages are not outputted to the pixels. According to some example embodiments, the inactive period may be the vertical blank period VBL.

InFIG. 3B, the frame rate of the display panel100may be a second frame rate less than the first frame rate. A length of the active period ACTIVE inFIG. 3Bmay be substantially the same as the length of the active period ACTIVE inFIG. 3A. A length of the vertical blank period VBL inFIG. 3Bmay be greater than the length of the vertical blank period VBL inFIG. 3A.

InFIG. 3C, the frame rate of the display panel100may be a third frame rate less than the second frame rate. A length of the active period ACTIVE inFIG. 3Cmay be substantially the same as the lengths of the active periods ACTIVE inFIGS. 3A and 3B. A length of the vertical blank period VBL inFIG. 3Cmay be greater than the length of the vertical blank period VBL inFIG. 3B.

FIG. 4is a timing diagram illustrating a gate signal GS outputted from the gate driver300ofFIG. 1and a data voltage VD charged at a pixel of the display panel100ofFIG. 1.FIG. 5is a circuit diagram illustrating the pixel of the display panel ofFIG. 1.

InFIG. 4, the display panel100may be driven in a frame rate which is less than a highest frame rate, and the data voltage VD may not mean the voltage outputted from the data driver500but the voltage charged at the pixel of the display panel100.

Referring toFIGS. 1 to 5, the data voltage VD is charged at the pixel in response to a first pulse of the gate signal GS ofFIG. 4. The pixel may include a switching element T connected to the gate line GL and the data line DL, a liquid crystal capacitor CLC and a storage capacitor CST which are connected to the switching element T.

As time passes, the data voltage VD charged at the pixel may gradually decrease due to a leakage current of the switching element T. When the frame rate of the display panel100is sufficiently high, the data voltage VD is recharged at the pixel in response to a second pulse of the gate signal GS so that a decrease of luminance due to the decrease of the data voltage VD may not be shown to a user.

However, the frame rate may be not sufficiently high in a variable frame rate driving method. Thus, the second pulse of the gate signal GS inFIG. 4may not be applied to the pixel so that the data voltage VD charged at the pixel may continuously decrease. Accordingly, the decrease of luminance due to the decrease of the data voltage VD may be shown to a user so that a display quality of the display apparatus may be deteriorated.

FIG. 6is a conceptual diagram illustrating the light source part BLU ofFIG. 1.FIG. 7is a timing diagram illustrating the gate signal GS outputted from the gate driver ofFIG. 1, the data voltage VD charged at the pixel of the display panel100ofFIG. 1and a light source driving signal provided to the light source part BLU ofFIG. 1.

Referring toFIGS. 1 to 7, the light source part BLU may include a plurality of light sources ML. The light sources ML may be mini LEDs. The mini LEDs may be independently driven. The mini LED may have a size much smaller than a normal LED so that the display apparatus including the mini LEDs may have a much greater resolution than a conventional display apparatus.

According to some example embodiments, a first light source of the light source part BLU outputs a first luminance in the active period when the data voltage VD is outputted to the pixel. The first light source of the light source part BLU outputs a second luminance greater than the first luminance in the inactive period when the data voltage VD is not outputted to the pixel. According to some example embodiments, the inactive period may be the vertical blank period VBL. Herein, the first light source may mean one of the light sources in the light source part BLU.

The light source driver600may output a light source driving signal to control a luminance of the light sources of the light source part BLU. For example, the light source driving signal may be a pulse width modulation (PWM) signal. The light source driver600may determine a duty ratio of the light source driving signal to a first duty ratio such that the first light source outputs the first luminance. The light source driver600may determine the duty ratio of the light source driving signal to a second duty ratio greater than the first duty ratio such that the first light source outputs the second luminance.

As shown inFIG. 7, a conventional light source driver outputs a light source driving signal PWM1having a same duty ratio W1in the active period and in the inactive period. Thus, when the frame rate is low, the luminance of the image may decrease due to the leakage current of the switching element T of the pixel.

The light source driver600according to some example embodiments, outputs the light source driving signal PWM2having a first duty ratio W1in the active period and a second duty ratio W2greater than the first duty ration W1in the inactive period. Thus, when the frame rate is low, the decrease of the luminance of the image due to the leakage current of the switching element T of the pixel may be compensated.

For example, when the frame rate is greater than a threshold frame rate, the light source driver600may control the first light source to output the first luminance in the active period and the inactive period.

When the frame rate is equal to or less than the threshold frame rate, the light source driver600may control the first light source to output the first luminance in the active period and the second luminance in the inactive period.

When the frame rate is greater than the threshold frame rate, the decrease of the luminance due to the leakage current of the switching transistor T may not be shown to the user. In contrast, when the frame rate is greater than a threshold frame rate, the decrease of the luminance due to the leakage current of the switching transistor T may be shown to the user. Thus, the light source driver600may determine whether the light source driver600operates the compensation of the luminance of the light source or not according to the threshold frame rate.

FIG. 8is a table illustrating a flicker value of the display panel100ofFIG. 1determined by a grayscale value of input image data and a frame rate.

Referring toFIGS. 1 to 8, if the data voltage VD charged at the pixel decreases much, a flicker due to a luminance difference may be shown to a user when the data voltage VD is refreshed at the pixel in a next frame. When the frame rate is low, the flicker may be great. In addition, the flicker may be varied according to the grayscale value of the input image data corresponding to the data voltage VD.

Thus, the second luminance to compensate the decrease of the luminance of the display panel100may be determined according to the frame rate of the display panel100and the grayscale value of the input image data IMG. When the flicker value according to the frame rate and the grayscale value is relatively great, the second luminance may be relatively great. When the flicker value according to the frame rate and the grayscale value is relatively little, the second luminance may be relatively little.

According to some example embodiments, the luminance of the light source may be compensated in the vertical blank period VBL to compensate the decrease of the luminance of the image due to the leakage current of the pixel in the low frame rate. Thus, the luminance of the image is compensated so that the display quality of the display apparatus may be enhanced.

FIG. 9is a timing diagram illustrating a gate signal GS outputted from a gate driver300of a display apparatus according to some example embodiments of the present inventive concept, a data voltage VD charged at a pixel of a display panel100and a light source driving signal PWM1and a light source driving current CURR provided to a light source part BLU.

The display apparatus and the method of driving the display apparatus according to some example embodiments is substantially the same as the display apparatus and the method of driving the display apparatus of the previous example embodiment explained referring toFIGS. 1 to 8except for the operation of the light source driver. Thus, the same reference numerals will be used to refer to the same or like parts as those described in the previous example embodiment ofFIGS. 1 to 8and any repetitive explanation concerning the above elements will be omitted.

Referring toFIGS. 1 to 6, 8 and 9, the display apparatus includes a display panel100and a display panel driver. The display panel driver includes a driving controller200, a gate driver300, a gamma reference voltage generator400and a data driver500. The display apparatus may further include a light source part BLU providing light to the display panel100and a light source driver600driving the light source part BLU. The display apparatus may further include a host700providing input image data to the driving controller200.

According to some example embodiments, a first light source of the light source part BLU outputs a first luminance in the active period when the data voltage VD is outputted to the pixel. The first light source of the light source part BLU outputs a second luminance greater than the first luminance in the inactive period when the data voltage VD is not outputted to the pixel. According to some example embodiments, the inactive period may be the vertical blank period VBL.

The light source driver600may output a light source driving signal to control a luminance of the light sources of the light source part BLU. For example, the light source driving signal may be a pulse width modulation (PWM) signal.

In case when the duty ratio of the light source driving signal PWM1is 100%, the duty ratio of the light source driving signal PWM1may not be further increased to increase the luminance of the display panel100.

Thus, when the duty ratio of the light source driving signal PWM1is 100%, the light source driver600may determine the light source driving current CURR to a first current L1such that the first light source outputs the first luminance. The light source driver600may determine the light source driving current CURR to a second current L2greater than the first current L1such that the first light source outputs the second luminance.

As shown inFIG. 7, the light source driver600according to some example embodiments, outputs the light source driving signal PWM2having a first duty ratio W1in the active period and a second duty ratio W2greater than the first duty ration W1in the inactive period. Thus, when the frame rate is low, the decrease of the luminance of the image due to the leakage current of the switching element T of the pixel may be compensated.

In addition, the light source driver600according to some example embodiments, may increase the level of the light source driving current CURR, in case when the duty ratio of the light source driving signal PWM1is 100%, so that the decrease of the luminance of the image due to the leakage current of the switching element T of the pixel may be compensated.

According to some example embodiments, the luminance of the light source may be compensated in the vertical blank period VBL to compensate the decrease of the luminance of the image due to the leakage current of the pixel in the low frame rate. Thus, the luminance of the image is compensated so that the display quality of the display apparatus may be enhanced.

FIG. 10is a conceptual diagram illustrating a light source part BLU of a display apparatus according to according to some example embodiments of the present inventive concept.FIG. 11is a timing diagram illustrating a light source driving signal PWMO and PWMI provided to the light source part BLU ofFIG. 10.

The display apparatus and the method of driving the display apparatus according to the present example embodiment is substantially the same as the display apparatus and the method of driving the display apparatus of the previous example embodiment explained referring toFIGS. 1 to 8except for the operation of the light source driver. Thus, the same reference numerals will be used to refer to the same or like parts as those described in the previous example embodiment ofFIGS. 1 to 8and any repetitive explanation concerning the above elements will be omitted.

Referring toFIGS. 1 to 8, 10 and 11, the display apparatus includes a display panel100and a display panel driver. The display panel driver includes a driving controller200, a gate driver300, a gamma reference voltage generator400and a data driver500. The display apparatus may further include a light source part BLU providing light to the display panel100and a light source driver600driving the light source part BLU. The display apparatus may further include a host700providing input image data to the driving controller200.

The light source part BLU may include a plurality of light sources. The light sources may be mini LEDs.

The light source part BLU may include an outermost light source MLO located at an outermost position of the light source part BLU and an inner light source MLI which is not the outermost light source MLO.

For the same grayscale value, the outermost light source MLO of the light source part BLU may output a luminance greater than a luminance of the light sources MLI which are not the outermost light source MLO. A luminance of an edge portion of the display panel100may have a low luminance due to a structure of the display apparatus or a small number of adjacent light sources compared to the inner light source MLI so that the display quality may be deteriorated.

Thus, the outermost light source MLO of the light source part BLU outputs the luminance greater than the luminance of the light sources MLI which are not the outermost light source MLO so that the display quality of the display panel100may be enhanced.

For example, the outermost light source MLO may mean the light sources located at an outermost portion along a first side, a second side, a third side and a fourth side of the light source part BLU.

The light source driver600may control a pulse width WO of the light source driving signal PWMO applied to the outermost light source MLO to be greater than a pulse with of the light source driving signal PWMI applied to the inner light source MLI.

The operation of the light source driver600ofFIG. 7may be applied to the present example embodiment. In addition, the operation of the light source driver600ofFIG. 9may be applied to the present example embodiment.

As shown inFIG. 7, the light source driver600according to some example embodiments, outputs the light source driving signal PWM2having a first duty ratio W1in the active period and a second duty ratio W2greater than the first duty ration W1in the inactive period. Thus, when the frame rate is low, the decrease of the luminance of the image due to the leakage current of the switching element T of the pixel may be compensated.

FIG. 12is a timing diagram illustrating a gate signal GS outputted from a gate driver300of a display apparatus according to an example embodiment of the present inventive concept, a data voltage VD charged at a pixel of a display panel100and a light source driving signal PWM2provided to a light source part600.

The display apparatus and the method of driving the display apparatus according to the present example embodiment is substantially the same as the display apparatus and the method of driving the display apparatus of the previous example embodiment explained referring toFIGS. 1 to 8except for the operation of the light source driver. Thus, the same reference numerals will be used to refer to the same or like parts as those described in the previous example embodiment ofFIGS. 1 to 8and any repetitive explanation concerning the above elements will be omitted.

Referring toFIGS. 1 to 6, 8 and 12, the display apparatus includes a display panel100and a display panel driver. The display panel driver includes a driving controller200, a gate driver300, a gamma reference voltage generator400and a data driver500. The display apparatus may further include a light source part BLU providing light to the display panel100and a light source driver600driving the light source part BLU. The display apparatus may further include a host700providing input image data to the driving controller200.

According to some example embodiments, a first light source of the light source part BLU outputs a first luminance in the active period when the data voltage VD is outputted to the pixel. The first light source of the light source part BLU outputs a second luminance greater than the first luminance in the inactive period when the data voltage VD is not outputted to the pixel. According to some example embodiments, the inactive period may be the vertical blank period VBL.

According to some example embodiments, the first light source may output gradually increasing luminance in the inactive period. As shown inFIG. 12, the data voltage VD may gradually decrease as time passes. Thus, when the luminance of the light source is gradually increased in the inactive period, the display quality of the display apparatus may be effectively compensated.

The light source driver600outputs the light source driving signal PWM2having a first duty ratio W1in the active period, a second duty ratio W2greater than the first duty ration W1, a third duty ratio W3greater than the second duty ration W2, a fourth duty ratio W4greater than the third duty ration W3and a fifth duty ratio W5greater than the fourth duty ration W4in the inactive period. Thus, when the frame rate is low, the decrease of the luminance of the image due to the leakage current of the switching element T of the pixel may be compensated.

According to some example embodiments, the luminance of the light source may be compensated in the vertical blank period VBL to compensate the decrease of the luminance of the image due to the leakage current of the pixel in the low frame rate. Thus, the luminance of the image is compensated so that the display quality of the display apparatus may be enhanced.

FIG. 13is a block diagram illustrating a driving controller200of a display apparatus according to an example embodiment of the present inventive concept.FIG. 14is a timing diagram illustrating a gate signal GS outputted from a gate driver300of the display apparatus ofFIG. 13, a data voltage VD charged at a pixel of a display panel100and a light source driving signal PWM2provided to a light source part600.

Referring toFIGS. 1, 4 to 6, 8, 13 and 12, the display apparatus includes a display panel100and a display panel driver. The display panel driver includes a driving controller200, a gate driver300, a gamma reference voltage generator400and a data driver500. The display apparatus may further include a light source part BLU providing light to the display panel100and a light source driver600driving the light source part BLU. The display apparatus may further include a host700providing input image data to the driving controller200.

The driving controller200may determine whether the input image data IMG represents a video image or a static image. When the input image data IMG represents the video image, the driving controller200determines the frame rate FR of the display panel100to a first frame rate. When the input image data IMG represents the static image, the driving controller200determines the frame rate FR of the display panel100to a second frame rate less than the first frame rate.

The driving controller200may include a frequency determiner220, a signal generator240and a data compensator260.

The frequency determiner220may determine the frame rate FR of the display apparatus based on the input image data IMG. When the input image data IMG represents a video image, the frame rate FR may be relatively high. When the input image data IMG represents a static image, the frame rate FR may be relatively low.

The frequency determiner220may determine a low frequency driving mode and a normal driving mode based on the input image data IMG. For example, when the input image data IMG represents a video image, the frequency determiner220may drive the display apparatus in the normal driving mode. For example, when the input image data IMG represents a static image, the frequency determiner220may drive the display apparatus in the low frequency driving mode.

In addition, the frequency determiner220may determine the low frequency driving mode and the normal driving mode based on an input mode of the display apparatus. For example, when the input mode of the display apparatus is Always On Mode, the frequency determiner220may drive the display apparatus in the low frequency driving mode.

The display panel100may be driven in a unit of frame. The display panel100may be refreshed in every frame in the normal driving mode. Thus, the normal driving mode includes only writing frames AF in which the data is written in the pixel.

The display panel100may be refreshed in the frequency of the low frequency driving mode in the low frequency driving mode. Thus, the low frequency driving mode includes the writing frames AF in which the data is written in the pixel and holding frames HF in which the written data is maintained without writing the data in the pixel.

For example, when the frequency of the normal driving mode is 60 Hz and the frequency of the low frequency driving mode is 1 Hz, the low frequency driving mode includes one writing frame AF and fifty nine holding frames HF in a second. For example, when the frequency of the normal driving mode is 60 Hz and the frequency of the low frequency driving mode is 1 Hz, fifty nine continuous holding frames HF are located between two adjacent writing frames AF.

For example, when the frequency of the normal driving mode is 60 Hz and the frequency of the low frequency driving mode is 10 Hz, the low frequency driving mode includes ten writing frame AF and fifty holding frames HF in a second. For example, when the frequency of the normal driving mode is 60 Hz and the frequency of the low frequency driving mode is 10 Hz, five continuous holding frames HF are located between two adjacent writing frames AF.

The frequency determiner220may output the frame rate FR to the signal generator240and the data compensator260.

The signal generator240may generate the first control signal CONT1to control an operation of the gate driver300based on the input control signal CONT and the frame rate FR and output the first control signal CONT1to the gate driver300. The signal generator240may generate the second control signal CONT2to control an operation of the data driver500based on the input control signal CONT and the frame rate FR and output the second control signal CONT2to the data driver500. The signal generator240may generate the third control signal CONT3to control an operation of the gamma reference voltage generator400based on the input control signal CONT and the frame rate FR and output the third control signal CONT3to the gamma reference voltage generator400.

The data compensator260may generate the data signal DATA based on the input image data IMG and the frame rate FR and output the data signal DATA to the data driver500. The data compensator260may compensate the input image data IMG to generate the data signal DATA. For example, the data compensator260may operate adaptive color correction using a gamma curve. For example, the data compensator260may operate dynamic capacitance compensation for compensating present frame data using previous frame data and the present frame data.

According to some example embodiments, a first light source of the light source part BLU outputs a first luminance in the active period when the data voltage VD is outputted to the pixel. The first light source of the light source part BLU outputs a second luminance greater than the first luminance in the inactive period when the data voltage VD is not outputted to the pixel. According to some example embodiments, the active period may be the writing frame AF and the inactive period may be the holding frame HF.

The light source driver600may output a light source driving signal to control a luminance of the light sources of the light source part BLU. For example, the light source driving signal may be a pulse width modulation (PWM) signal. The light source driver600may determine a duty ratio of the light source driving signal to a first duty ratio such that the first light source outputs the first luminance. The light source driver600may determine the duty ratio of the light source driving signal to a second duty ratio greater than the first duty ratio such that the first light source outputs the second luminance.

As shown inFIG. 14, a conventional light source driver outputs a light source driving signal PWM1having a same duty ratio W1in the active period and in the inactive period. Thus, when the frame rate is low, the luminance of the image may decrease due to the leakage current of the switching element T of the pixel.

The light source driver600according to some example embodiments, outputs the light source driving signal PWM2having a first duty ratio W1in the active period AF and a second duty ratio W2greater than the first duty ration W1in the inactive period HF. Thus, when the frame rate is low, the decrease of the luminance of the image due to the leakage current of the switching element T of the pixel may be compensated.

For example, when the frame rate is greater than a threshold frame rate, the light source driver600may control the first light source to output the first luminance in the active period AF and the inactive period HF.

When the frame rate is equal to or less than the threshold frame rate, the light source driver600may control the first light source to output the first luminance in the active period AF and the second luminance in the inactive period HF.

According to some example embodiments, the luminance of the light source may be compensated in the holding frame HF to compensate the decrease of the luminance of the image due to the leakage current of the pixel in the low frame rate. Thus, the luminance of the image is compensated so that the display quality of the display apparatus may be enhanced.

FIG. 15is a timing diagram illustrating a gate signal GS outputted from a gate driver300of a display apparatus according to an example embodiment of the present inventive concept, a data voltage VD charged at a pixel of a display panel100and a light source driving signal PWM2provided to a light source part600.

The display apparatus and the method of driving the display apparatus according to the present example embodiment is substantially the same as the display apparatus and the method of driving the display apparatus of the previous example embodiment explained referring toFIGS. 13 and 14except for the operation of the light source driver. Thus, the same reference numerals will be used to refer to the same or like parts as those described in the previous example embodiment ofFIGS. 13 and 14and any repetitive explanation concerning the above elements will be omitted.

Referring toFIGS. 1, 4 to 6, 8, 13 and 15, the display apparatus includes a display panel100and a display panel driver. The display panel driver includes a driving controller200, a gate driver300, a gamma reference voltage generator400and a data driver500. The display apparatus may further include a light source part BLU providing light to the display panel100and a light source driver600driving the light source part BLU. The display apparatus may further include a host700providing input image data to the driving controller200.

According to some example embodiments, a first light source of the light source part BLU outputs a first luminance in the active period when the data voltage VD is outputted to the pixel. The first light source of the light source part BLU outputs a second luminance greater than the first luminance in the inactive period when the data voltage VD is not outputted to the pixel. According to some example embodiments, the active period may be the writing frame AF and the inactive period may be the holding frame HF.

According to some example embodiments, the first light source may output gradually increasing luminance in the inactive period HF. As shown inFIG. 15, the data voltage VD may gradually decrease as time passes. Thus, when the luminance of the light source is gradually increased in the inactive period HF, the display quality of the display apparatus may be effectively compensated.

The light source driver600outputs the light source driving signal PWM2having a first duty ratio W1in the active period AF, a second duty ratio W2greater than the first duty ration W1, a third duty ratio W3greater than the second duty ration W2, a fourth duty ratio W4greater than the third duty ration W3and a fifth duty ratio W5greater than the fourth duty ration W4in the inactive period HF. Thus, when the frame rate is low, the decrease of the luminance of the image due to the leakage current of the switching element T of the pixel may be compensated.

According to some example embodiments, the luminance of the light source may be compensated in the holding frame HF to compensate the decrease of the luminance of the image due to the leakage current of the pixel in the low frame rate. Thus, the luminance of the image is compensated so that the display quality of the display apparatus may be enhanced.

According to the present inventive concept as explained above, the display quality of the display apparatus may be enhanced.