Display device and method of driving same

Abstract

The invention discloses a display device and a driving method thereof. The display device includes: a display panel including pixels; a drive control section that receives input image data including an input gray level from a host, and generates a data signal including an output gray level based on the input image data; and a data driving section which converts the data signal into a data voltage and supplies the data voltage to the display panel. When a driving frequency of the display panel is changed from a high frequency to a low frequency, an output gray level of a first low frequency frame having the low frequency is less than or equal to the input gray level.

Description

Technical Field

[0001] The present invention relates to a display device and a method for driving the display device, and more particularly, to a display device with improved display quality in variable frequency driving and a method for driving the display device. Background Art

[0002] Generally, a display device includes a display panel and a display panel driving unit. The display panel includes gate lines, data lines, emission lines and pixels. The display panel driving unit includes a gate driving unit that provides a gate signal to the gate line, a data driving unit that provides a data voltage to the data line, an emission driving unit that provides an emission signal to the emission line, and a driving control unit that controls the gate driving unit, the data driving unit and the emission driving unit.

[0003] When the driving frequency of the display panel is changed from a high frequency to a low frequency, the hysteresis characteristic of the driving transistor of the pixel may be changed, and a brightness difference of the display panel may occur. The brightness difference of the display panel may be recognized by a user as flicker. Summary of the invention

[0004] An object of the present invention is to provide a display device that reduces brightness differences when a driving frequency of a display panel is changed from a high frequency to a low frequency.

[0005] Another object of the present invention is to provide a method for driving the display device.

[0006] In order to achieve an object of the present invention, a display device according to an embodiment of the present invention includes: a display panel including pixels; a drive control unit receiving input image data including input grayscale from a host, generating a data signal including output grayscale based on the input image data; and a data drive unit converting the data signal into a data voltage and providing the data voltage to the display panel. When the driving frequency of the display panel is changed from a high frequency to a low frequency, the output grayscale of the first low-frequency frame having the low frequency is less than or equal to the input grayscale.

[0007] In one embodiment, the output gray level of the first low-frequency frame may be less than or equal to the output gray level of the high-frequency frame having the high frequency.

[0008] In one embodiment, when a frequency interval that is a difference between the high frequency and the low frequency is greater than or equal to a reference frequency interval, the output gray level of the first low frequency frame may be smaller than the input gray level.

[0009] In one embodiment, when the frequency interval is smaller than the reference frequency interval, the output gray level of the first low-frequency frame may be equal to the input gray level.

[0010] In one embodiment, when the input grayscale changes, the reference frequency interval may change.

[0011] In one embodiment, when the input gray level decreases, the reference frequency interval may decrease.

[0012] In one embodiment, the larger the frequency interval as the difference between the high frequency and the low frequency is, the larger the average brightness of the first low-frequency frame may be.

[0013] In one embodiment, the greater the difference between the average brightness of the first low-frequency frame and the target brightness corresponding to the input grayscale, the larger the compensation grayscale of the first low-frequency frame may be, wherein the compensation grayscale of the first low-frequency frame is the difference between the input grayscale and the output grayscale of the first low-frequency frame.

[0014] In one embodiment, the output gray level of the second low-frequency frame having the low frequency may be greater than or equal to the output gray level of the first low-frequency frame and may be less than or equal to the input gray level.

[0015] In one embodiment, in the first low-frequency frame and the second low-frequency frame, the output gray level may gradually increase toward the input gray level.

[0016] In order to achieve another object of the present invention, a method for driving a display device according to an embodiment of the present invention comprises the following steps: receiving input image data including an input grayscale from a host, generating a data signal including an output grayscale based on the input image data; and converting the data signal into a data voltage, and providing the data voltage to a display panel. When the driving frequency of the display panel is changed from a high frequency to a low frequency, the output grayscale of the first low-frequency frame having the low frequency is less than or equal to the input grayscale.

[0017] In one embodiment, the output gray level of the first low-frequency frame may be less than or equal to the output gray level of the high-frequency frame having the high frequency.

[0018] In one embodiment, when a frequency interval that is a difference between the high frequency and the low frequency is greater than or equal to a reference frequency interval, the output gray level of the first low frequency frame may be smaller than the input gray level.

[0019] In one embodiment, when the frequency interval is smaller than the reference frequency interval, the output gray level of the first low-frequency frame may be equal to the input gray level.

[0020] In one embodiment, when the input grayscale changes, the reference frequency interval may change.

[0021] In one embodiment, when the input gray level decreases, the reference frequency interval may decrease.

[0022] In one embodiment, the larger the frequency interval as the difference between the high frequency and the low frequency is, the larger the average brightness of the first low-frequency frame may be.

[0023] In one embodiment, the greater the difference between the average brightness of the first low-frequency frame and the target brightness corresponding to the input grayscale, the larger the compensation grayscale of the first low-frequency frame may be, wherein the compensation grayscale of the first low-frequency frame is the difference between the input grayscale and the output grayscale of the first low-frequency frame.

[0024] In one embodiment, the output gray level of the second low-frequency frame having the low frequency may be greater than or equal to the output gray level of the first low-frequency frame, and may be less than or equal to the input gray level.

[0025] In one embodiment, in the first low-frequency frame and the second low-frequency frame, the output gray level may gradually increase toward the input gray level.

[0026] According to the display device and the driving method of the display device according to the embodiment of the present invention, when the driving frequency of the display panel is changed from a high frequency to a low frequency, the output gray level of the first low-frequency frame having the low frequency can be less than or equal to the input gray level. Accordingly, the brightness difference when the driving frequency of the display panel is changed from the high frequency to the low frequency can be reduced.

[0027] However, the effects of the present invention are not limited to the above-mentioned effects, and can be variously extended without departing from the concept and scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a block diagram showing a display device according to an embodiment of the present invention.

[0029] Figure 2 It is shown Figure 1 Conceptual diagram of the driving frequency of the display panel.

[0030] Figure 3 It is shown Figure 1 A circuit diagram of an example of a pixel included in a display device.

[0031] Figure 4 is a graph showing target brightness according to an input gray level.

[0032] Figure 5 is a diagram showing an example of the brightness of the display panel when the gray scale compensation operation is not performed.

[0033] Figure 6 It is shown that it is recognized by the user Figure 5 A diagram of the brightness of the display panel.

[0034] Figure 7 It is shown Figure 5 A diagram of the brightness of a display panel when performing a grayscale compensation operation.

[0035] Figure 8 is a diagram showing an example of the brightness of the display panel when the frequency interval is smaller than the reference frequency interval.

[0036] Fig. 9 is a diagram showing an example of the brightness of the display panel when the frequency interval is greater than or equal to the reference frequency interval.

[0037] Fig.10 It is shown Fig. 9 A diagram of the brightness of a display panel when performing a grayscale compensation operation.

[0038] Fig.11 is a diagram showing reference frequency intervals according to high gray levels and low gray levels.

[0039] Fig.12 is a block diagram illustrating an electronic device according to an embodiment of the present invention.

[0040] Fig.13 It is shown Fig.12 FIG. 1 is a diagram of an example in which the electronic device is implemented as a smart phone.

[0041] Description of Reference Numerals DETAILED DESCRIPTION

[0042] Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

[0043] Figure 1 is a block diagram showing a display device 10 according to an embodiment of the present invention.

[0044] Reference Figure 1 The display device 10 may include a display panel 100 and a display panel driving unit. The display panel driving unit may include a driving control unit 200, a gate driving unit 300, a gamma reference voltage generating unit 400, a data driving unit 500, and an emission driving unit 600. The display device 10 may further include a host 700.

[0045] For example, the drive control unit 200 and the data drive unit 500 may be formed as one body. For example, the drive control unit 200, the gamma reference voltage generating unit 400 and the data drive unit 500 may be formed as one body. For example, the drive control unit 200, the gate drive unit 300, the gamma reference voltage generating unit 400 and the data drive unit 500 may be formed as one body. For example, the drive control unit 200, the gate drive unit 300, the gamma reference voltage generating unit 400, the data drive unit 500 and the emission drive unit 600 may be formed as one body. In addition, the drive module in which at least the drive control unit 200 and the data drive unit 500 are formed as one body may be named as a timing controller embedded data driver (TED: Timing Controller Embedded Data Driver).

[0046] The display panel 100 may include a display portion displaying an image and a peripheral portion disposed adjacent to the display portion.

[0047] For example, the display panel 100 may be an organic light emitting diode display panel including an organic light emitting diode. As another example, the display panel 100 may be a quantum dot organic light emitting diode display panel including an organic light emitting diode and a quantum dot color filter. As another example, the display panel 100 may be a quantum dot nano light emitting diode display panel including a nano light emitting diode and a quantum dot color filter. As another example, the display panel 100 may be a liquid crystal display panel including a liquid crystal layer.

[0048] The display panel 100 may include a gate line GL, a data line DL, an emission line EML, and pixels P electrically connected to the gate line GL, the data line DL, and the emission line EML. The gate line GL may extend along a first direction, the data line DL may extend along a second direction crossing the first direction, and the emission line EML may extend along the first direction.

[0049] The drive control unit 200 may receive input image data IMG and an input control signal CONT from the host 700. The input image data IMG may include information on grayscale, and the grayscale of the input image data IMG may be named as input grayscale IG. For example, the input image data IMG may include red image data, green image data, and blue image data. According to an embodiment, the input image data IMG may also include white image data. As another example, the input image data IMG may include magenta image data, yellow image data, and cyan image data. The input control signal CONT may include a main clock signal and a data enable signal. The input control signal CONT may also include a vertical synchronization signal and a horizontal synchronization signal.

[0050] The driving control part 200 may generate a first control signal CONT1 , a second control signal CONT2 , a third control signal CONT3 , a fourth control signal CONT4 , and a data signal DATA based on the input image data IMG and the input control signal CONT.

[0051] The driving control part 200 may generate the first control signal CONT1 for controlling the operation of the gate driving part 300 based on the input control signal CONT, and output the first control signal CONT1 to the gate driving part 300. The first control signal CONT1 may include a vertical start signal and a gate clock signal.

[0052] The driving control part 200 generates the second control signal CONT2 for controlling the operation of the data driving part 500 based on the input control signal CONT, and outputs the second control signal CONT2 to the data driving part 500. The second control signal CONT2 may include a horizontal start signal and a load signal.

[0053] The drive control part 200 may generate the data signal DATA based on the input image data IMG. The data signal DATA may include information on a grayscale, and the grayscale of the data signal DATA may be named an output grayscale OG. The output grayscale OG may be calculated by a grayscale compensation operation on the input grayscale IG. The drive control part 200 may output the data signal DATA to the data driving part 500.

[0054] The driving control part 200 may generate the third control signal CONT3 for controlling the operation of the gamma reference voltage generating part 400 based on the input control signal CONT, and output the third control signal CONT3 to the gamma reference voltage generating part 400 .

[0055] The driving control part 200 may generate the fourth control signal CONT4 for controlling the operation of the emission driving part 600 based on the input control signal CONT, and output the fourth control signal CONT4 to the emission driving part 600 .

[0056] The gate driving part 300 may generate a gate signal for driving the gate line GL in response to the first control signal CONT1 received from the driving control part 200. The gate driving part 300 may output the gate signal to the gate line GL.

[0057] In one embodiment, the gate driving unit 300 may be integrated on the periphery of the display panel 100 .

[0058] The gamma reference voltage generating part 400 may generate a gamma reference voltage VGREF in response to the third control signal CONT3 received from the driving control part 200. The gamma reference voltage generating part 400 may provide the gamma reference voltage VGREF to the data driving part 500. The gamma reference voltage VGREF may have a value corresponding to each of the data signals DATA.

[0059] In one embodiment, the gamma reference voltage generating part 400 may be disposed in the driving control part 200 or in the data driving part 500 .

[0060] The data driving unit 500 may receive the second control signal CONT2 and the data signal DATA from the driving control unit 200, and may receive the gamma reference voltage VGREF from the gamma reference voltage generating unit 400. The data driving unit 500 may convert the data signal DATA into an analog data voltage VDATA (refer to Figure 3 ). The data driving part 500 may output the data voltage VDATA to the data line DL.

[0061] The emission driving part 600 may generate an emission signal for driving the emission line EML in response to the fourth control signal CONT4 received from the driving control part 200. The emission driving part 600 may output the emission signal to the emission line EML.

[0062] In one embodiment, the emission driving unit 600 may be integrated into the peripheral portion of the display panel 100. In one embodiment, the emission driving unit 600 may be mounted on the peripheral portion of the display panel 100.

[0063] For ease of explanation, Figure 1 , the gate driving unit 300 is arranged on the first side of the display panel 100 and the emission driving unit 600 is arranged on the second side of the display panel 100, but the present invention is not limited thereto. For example, the gate driving unit 300 and the emission driving unit 600 may both be arranged on the first side of the display panel 100. For example, the gate driving unit 300 and the emission driving unit 600 may both be arranged on both sides of the display panel 100. For example, the gate driving unit 300 and the emission driving unit 600 may also be formed as one body.

[0064] Figure 2 It is shown Figure 1 A conceptual diagram of a driving frequency of the display panel 100.

[0065] Reference Figure 2 , the display panel 100 may be driven at a variable frequency. A first frame FR1 having a first driving frequency may include a first effective interval AC1 and a first blank interval BL1. A second frame FR2 having a second driving frequency different from the first driving frequency may include a second effective interval AC2 and a second blank interval BL2. A third frame FR3 having a third driving frequency different from the first driving frequency and the second driving frequency may include a third effective interval AC3 and a third blank interval BL3.

[0066] For example, Figure 2 As shown, the first frame FR1 may have a driving frequency of 120 Hz, the second frame FR2 may have a driving frequency of 90 Hz, and the third frame FR3 may have a driving frequency of 60 Hz.

[0067] The first active interval AC1 may have the same length as the second active interval AC2, and the first blank interval BL1 may have a different length from the second blank interval BL2. That is, the frame period of the second driving frequency may be different from the frame period of the first driving frequency.

[0068] The second active interval AC2 may have the same length as the third active interval AC3, and the second blank interval BL2 may have a different length from the third blank interval BL3. That is, the frame period of the third driving frequency may be different from the frame period of the second driving frequency.

[0069] Figure 3 It is shown Figure 1 FIG. 1 is a circuit diagram of an example of a pixel P included in the display device 10 . Figure 4 is a graph showing the target brightness TL according to the input gray level IG.

[0070] Reference Figure 3 , the pixel P may include a first transistor T1 to a seventh transistor T7 and a light emitting element EE.

[0071] The first transistor T1 (ie, the driving transistor) may include a gate electrode connected to the first node N1 , a first electrode connected to the second node N2 , and a second electrode connected to the third node N3 .

[0072] The second transistor T2 may include a gate electrode to which a data write gate signal GW is applied, a first electrode to which a data voltage VDATA is applied, and a second electrode connected to the second node N2. The data voltage VDATA may be applied to the pixel P according to the data write gate signal GW.

[0073] The third transistor T3 may include a gate electrode to which a compensation gate signal GC is applied, a first electrode connected to the first node N1, and a second electrode connected to the third node N3. A threshold voltage of the first transistor T1 may be compensated according to the compensation gate signal GC.

[0074] The fourth transistor T4 may include a gate electrode to which the data initialization gate signal GI is applied, a first electrode to which the initialization voltage VINIT is applied, and a second electrode connected to the first node N1. The gate electrode of the first transistor T1 may be initialized to the initialization voltage VINIT according to the data initialization gate signal GI.

[0075] The fifth transistor T5 may include a gate electrode to which the emission signal EM is applied, a first electrode to which the first driving voltage ELVDD is applied, and a second electrode connected to the second node N2.

[0076] The sixth transistor T6 may include a gate electrode to which the emission signal EM is applied, a first electrode connected to the third node N3 , and a second electrode connected to the anode electrode of the light emitting element EE.

[0077] The seventh transistor T7 may include a gate electrode to which a light emitting element initialization gate signal GB is applied, a first electrode to which a light emitting element initialization voltage VAINIT is applied, and a second electrode connected to the anode electrode of the light emitting element EE. The anode electrode of the light emitting element EE may be initialized to the light emitting element initialization voltage VAINIT according to the light emitting element initialization gate signal GB.

[0078] The light emitting element EE may include the anode electrode and a cathode electrode to which a second driving voltage ELVSS is applied. The second driving voltage ELVSS may be lower than the first driving voltage ELVDD.

[0079] The pixel P may further include a storage capacitor CST including a first electrode to which the first driving voltage ELVDD is applied and a second electrode connected to the first node N1. The storage capacitor CST may store a voltage corresponding to the data voltage VDATA.

[0080] The driving current ID of the pixel P may flow in the order of the fifth transistor T5, the first transistor T1, and the sixth transistor T6 to drive the light emitting element EE. The brightness of the light emitting element EE may be determined by the intensity of the driving current ID. The intensity of the driving current ID may be determined by the level of the data voltage VDATA. The level of the data voltage VDATA may be determined by the input gray level IG and the output gray level OG. Figure 4 As shown in the 2.2 gamma curve of FIG. 1 , the target brightness TL may increase with the increase of the input gray level IG. For different driving frequencies, the input gray level IG and the corresponding target brightness TL may be the same.

[0081] In the case where all the transistors included in the pixel P are P-type transistors, the pixel P may flicker due to the leakage current of the transistors during low-frequency driving. Therefore, a part of the transistors included in the pixel P may be N-type transistors. In the present embodiment, the third transistor T3 and the fourth transistor T4 may be the N-type transistors, and the first transistor T1, the second transistor T2, the fifth transistor T5, the sixth transistor T6 and the seventh transistor T7 may be the P-type transistors. However, the present invention is not limited thereto. The present invention can be applied to pixels including only the P-type transistors, and can also be applied to pixels including only the N-type transistors.

[0082] Figure 5 is a diagram showing an example of the brightness of the display panel 100 when the gray scale compensation operation is not performed. Figure 6 It is shown that it is recognized by the user Figure 5 FIG. 1 is a diagram showing the brightness of the display panel 100 .

[0083] Reference Figure 5 and Figure 6 , the driving frequency of the display panel 100 may be changed from the high frequency DFH to the low frequency DFL lower than the high frequency DFH. For example, the high frequency DFH may be 120 Hz, and the low frequency DFL may be 60 Hz, in which case the frequency interval FI as the difference between the high frequency DFH and the low frequency DFL may be 60 Hz. For example, the input gray level IG may be 128 gray levels, and the target brightness TL corresponding to the input gray level IG may be 100 nit. In the high frequency DFH and the low frequency DFL, the target brightness TL according to the input gray level IG may be the same. Since the low frequency DFL is lower than the high frequency DFH, the frame period of the low frequency DFL may be longer than the frame period of the high frequency DFH.

[0084] In addition, when the driving frequency of the display panel 100 is changed from the high frequency DFH to the low frequency DFL, the hysteresis characteristic of the driving transistor T1 may be changed. The hysteresis characteristic of the driving transistor T1 may represent the driving current ID according to the gate-source voltage of the driving transistor T1. Therefore, when the hysteresis characteristic of the driving transistor T1 is changed, the brightness of the display panel 100 according to the same input gray level IG may be different. The brightness difference of the display panel 100 may be recognized by the user as flicker.

[0085] Specifically, in the last high-frequency frame DFH_FRL having the high frequency DFH, the hysteresis characteristic of the driving transistor T1 does not change, and therefore, the light waveform of the last high-frequency frame DFH_FRL may be the light waveform G1 where the flicker of the high frequency DFH is not recognized. The peak brightness of the last high-frequency frame DFH_FRL may be the peak brightness DF1_PL of the light waveform G1 where the flicker of the high frequency DFH is not recognized. When the area of ​​the light waveform of the last high-frequency frame DFH_FRL is divided by the frame period of the high frequency DFH, as Figure 6 As shown, the average brightness of the last high-frequency frame DFH_FRL can be calculated. Since the light waveform of the last high-frequency frame DFH_FRL is the light waveform G1 in which the flicker of the high frequency DFH is not recognized, the average brightness of the last high-frequency frame DFH_FRL can be the target brightness TL. The average brightness of the last high-frequency frame DFH_FRL can be recognized by the user as the brightness of the display panel 100.

[0086] In the first low-frequency frame DFL_FR1 having the low-frequency DFL, the hysteresis characteristic of the driving transistor T1 is changed, and therefore, the light waveform of the first low-frequency frame DFL_FR1 may be the light waveform G2' in which the flicker of the low-frequency DFL is recognized. The peak brightness of the first low-frequency frame DFL_FR1 may be the peak brightness DF2_PL' of the light waveform G2' in which the flicker of the low-frequency DFL is recognized. When the area of ​​the light waveform of the first low-frequency frame DFL_FR1 is divided by the frame period of the low-frequency DFL, as Figure 6 As shown, the average brightness of the first low-frequency frame DFL_FR1 can be calculated. Since the light waveform of the first low-frequency frame DFL_FR1 is the light waveform G2' by which the flicker of the low frequency DFL is recognized, the average brightness of the first low-frequency frame DFL_FR1 can be different from the target brightness TL. The average brightness of the first low-frequency frame DFL_FR1 can be recognized by the user as the brightness of the display panel 100.

[0087] In the second low-frequency frame DFL_FR2 having the low-frequency DFL, the hysteresis characteristic of the driving transistor T1 is restored, and therefore, the light waveform of the second low-frequency frame DFL_FR2 may be the light waveform G2 where the flicker of the low-frequency DFL is not recognized. The peak brightness of the second low-frequency frame DFL_FR2 may be the peak brightness DF2_PL of the light waveform G2 where the flicker of the low-frequency DFL is not recognized. When the area of ​​the light waveform of the second low-frequency frame DFL_FR2 is divided by the frame period of the low-frequency DFL, as Figure 6 As shown, the average brightness of the second low-frequency frame DFL_FR2 can be calculated. Since the light waveform of the second low-frequency frame DFL_FR2 is the light waveform G2 in which the flicker of the low frequency DFL is not recognized, the average brightness of the second low-frequency frame DFL_FR2 can be the target brightness TL. The average brightness of the second low-frequency frame DFL_FR2 can be recognized by the user as the brightness of the display panel 100.

[0088] As described above, when the driving frequency of the display panel 100 is changed from the high frequency DFH to the low frequency DFL, the hysteresis characteristic of the driving transistor T1 may be changed in the first low frequency frame DFL_FR1, and the peak brightness DF2_PL' of the first low frequency frame DFL_FR1 may be greater than the peak brightness DF2_PL of the light waveform G2 where the flicker of the low frequency DFL is not recognized. Furthermore, the area difference between the area of ​​the light waveform G2' of the first low frequency frame DFL_FR1 and the area of ​​the light waveform G2 where the flicker of the low frequency DFL is not recognized may be recognized by the user as the flicker. If the area difference LUM_AREA_DIFF between the area of ​​the light waveform G2 where the flicker of the low frequency DFL is not recognized and the area of ​​the light waveform G2' where the flicker of the low frequency DFL is recognized is divided by the frame period of the low frequency DFL, the brightness difference LUM_DIFF of the first low frequency frame DFL_FR1 may be calculated.

[0089] In addition, the difference between the peak brightness DF2_PL' of the light waveform G2' in which the flicker of the low frequency DFL is recognized and the peak brightness DF2_PL of the light waveform G2 in which the flicker of the low frequency DFL is not recognized may be named as a peak brightness difference PL_DIFF.

[0090] Figure 7 It is shown Figure 5 FIG. 1 is a diagram showing the brightness of the display panel 100 when performing a grayscale compensation operation.

[0091] Reference Figures 5 to 7 , when the driving frequency of the display panel 100 is changed from the high frequency DFH to the low frequency DFL, the output gray level OG of the first low frequency frame DFL_FR1 having the low frequency DFL may be less than or equal to the input gray level IG. In addition, the output gray level OG of the first low frequency frame DFL_FR1 may be less than or equal to the output gray level OG of the high frequency frame having the high frequency DFH. When the output gray level OG of the first low frequency frame DFL_FR1 is less than the input gray level IG, a gray compensation operation may be performed by the driving control part 200. On the contrary, when the output gray level OG of the first low frequency frame DFL_FR1 is the same as the input gray level IG, the gray compensation operation by the driving control part 200 may not be performed.

[0092] The peak brightness DF2_PL' of the first low-frequency frame DFL_FR1 is greater than the peak brightness DF2_PL of the light waveform G2 in which the flicker of the low-frequency DFL is not recognized, and therefore, the drive control section 200 may compensate the input gray level IG by reducing the output gray level OG. Therefore, the output gray level OG of the first low-frequency frame DFL_FR1 may be less than the input gray level IG. For example, the input gray level IG may be 128 gray levels, and the output gray level OG of the first low-frequency frame DFL_FR1 may be 126 gray levels. Therefore, the difference between the input gray level IG and the output gray level OG may be named as a compensation gray level CG, and the compensation gray level CG of the first low-frequency frame DFL_FR1 may be two gray levels.

[0093] The compensated grayscale CG of the first low-frequency frame DFL_FR1 may correspond to the luminance difference LUM_DIFF of the first low-frequency frame DFL_FR1. Accordingly, the peak luminance DF2_PL' of the first low-frequency frame DFL_FR1 may be compensated by the peak luminance DF2_PL of the light waveform G2 in which the flicker of the low frequency DFL is not recognized. Therefore, the flicker may not be recognized by the user in the first low-frequency frame DFL_FR1 of the low frequency DFL.

[0094] Figure 8 is a diagram showing an example of the brightness of the display panel 100 when the frequency interval FI is smaller than the reference frequency interval FI_REF.

[0095] Reference Figure 8 , when the frequency interval FI is less than the reference frequency interval FI_REF, the output gray level OG of the first low-frequency frame DFL_FR1 may be the same as the input gray level IG. That is, the gray compensation operation by the drive control unit 200 may not be performed. When the input gray level IG is changed, the reference frequency interval FI_REF may be changed. Specifically, when the input gray level IG decreases, the reference frequency interval FI_REF may decrease. Fig.11 This will be discussed later in the text.

[0096] For example, the high frequency DFH may be 120 Hz, the low frequency DFL may be 90 Hz, in which case the frequency interval FI may be 30 Hz. For example, the input gray level IG may be 128 gray levels, in which case the reference frequency interval FI_REF may be 40 Hz. That is, the frequency interval FI may be smaller than the reference frequency interval FI_REF.

[0097] The difference between the frame period of the high frequency DFH and the frame period of the low frequency DFL and the peak brightness difference PL_DIFF may decrease with the frequency interval FI. As the peak brightness difference PL_DIFF decreases, the area difference LUM_AREA_DIFF between the area of ​​the light waveform G2 where the flicker of the low frequency DFL is not recognized and the area of ​​the light waveform G2' where the flicker of the low frequency DFL is recognized may decrease, and the brightness difference LUM_DIFF of the first low frequency frame DFL_FR1 may decrease. The brightness difference LUM_DIFF of the first low frequency frame DFL_FR1 may not be sufficiently recognized as flicker by the user, and the input gray level IG may not be compensated.

[0098] Fig. 9 is a diagram showing an example of the brightness of the display panel 100 when the frequency interval FI is greater than or equal to the reference frequency interval FI_REF. Fig.10 It is shown Fig. 9 FIG. 1 is a diagram showing the brightness of the display panel 100 when performing a grayscale compensation operation.

[0099] Reference Fig. 9 and Fig.10 When the frequency interval FI is greater than or equal to the reference frequency interval FI_REF, the output gray level OG of the first low frequency frame DFL_FR1 may be less than the input gray level IG. That is, the gray compensation operation may be performed by the driving control part 200 .

[0100] For example, the high frequency DFH may be 120 Hz, the low frequency DFL may be 48 Hz, in which case the frequency interval FI may be 72 Hz. For example, the input gray level IG may be 128 gray levels, in which case the reference frequency interval FI_REF may be 40 Hz. That is, the frequency interval FI may be greater than the reference frequency interval FI_REF.

[0101] When the frequency interval FI is large, the average brightness of the first low frequency frame DFL_FR1 may be large. When the difference between the average brightness of the first low frequency frame DFL_FR1 and the target brightness TL is large, the compensation grayscale CG of the first low frequency frame DFL_FR1 may be large. For example, the input grayscale IG may be 128 grayscales, and the output grayscale OG of the first low frequency frame DFL_FR1 may be 124 grayscales. That is, the compensation grayscale CG of the first low frequency frame DFL_FR1 may be 4 grayscales.

[0102] The output gray level OG of the second low frequency frame DFL_FR2 may be greater than or equal to the output gray level OG of the first low frequency frame DFL_FR1, and less than or equal to the input gray level IG. When the output gray level OG of the second low frequency frame DFL_FR2 is less than the input gray level IG, the gray level compensation operation may be performed by the driving control part 200. On the contrary, when the output gray level OG of the second low frequency frame DFL_FR2 is the same as the input gray level IG, the gray level compensation operation by the driving control part 200 may not be performed. In particular, when the gray level compensation operation is performed in the first low frequency frame DFL_FR1 and the second low frequency frame DFL_FR2, the output gray level OG may gradually increase toward the input gray level IG in the first low frequency frame DFL_FR1 and the second low frequency frame DFL_FR2.

[0103] When the frequency interval FI is larger, the average brightness of the second low frequency frame DFL_FR2 may be larger. When the difference between the average brightness of the second low frequency frame DFL_FR2 and the target brightness TL is larger, the compensation grayscale CG of the second low frequency frame DFL_FR2 may be larger. For example, the input grayscale IG may be 128 grayscales, and the output grayscale OG of the second low frequency frame DFL_FR2 may be 126 grayscales. That is, the compensation grayscale CG of the second low frequency frame DFL_FR2 may be 2 grayscales.

[0104] Fig.11 is a diagram showing reference frequency intervals according to high gray levels and low gray levels.

[0105] Reference Fig.11 When the input gray level IG changes, the reference frequency interval FI_REF may change. Specifically, when the input gray level IG decreases, the reference frequency interval FI_REF may decrease.

[0106] The luminance difference LUM_DIFF of the first low-frequency frame DFL_FR1 increases as the frequency interval FI increases, so the possibility that the user recognizes the flicker in the first low-frequency frame DFL_FR1 increases. Fig.11As shown, when the brightness difference LUM_DIFF of the first low-frequency frame DFL_FR1 is the same, the ratio of the brightness difference LUM_DIFF of the first low-frequency frame DFL_FR1 to the brightness of the display panel 100 in the low gray level can be greater than that in the high gray level. Therefore, even if a small brightness difference is generated, the possibility that the user recognizes the flicker at the low gray level increases. Therefore, in the low gray level, the reference frequency interval FI_REF should be small.

[0107] Fig.12 is a block diagram showing an electronic device 1000 according to an embodiment of the present invention. Fig.13 It is shown Fig.12 The electronic device 1000 is implemented as an example of a smart phone.

[0108] Reference Fig.12 and Fig.13 , the electronic device 1000 may include a processor 1010, a memory device 1020, a storage device 1030, an input / output device 1040, a power supply 1050, and a display device 1060. In this case, the display device 1060 may be Figure 1 The display device 10. In addition, the electronic device 1000 may further include a plurality of ports capable of communicating with a video card, a sound card, a memory card, a universal serial bus (USB) device, etc. or communicating with other systems.

[0109] According to one embodiment, Fig.13 As shown, the electronic device 1000 may be implemented as a smart phone. However, this is only exemplary, and the electronic device 1000 is not limited thereto. For example, the electronic device 1000 may be implemented as a mobile phone, a video phone, a smart tablet, a smart watch, a tablet PC, a vehicle navigation system, a computer monitor, a notebook computer, a head-mounted display device, etc.

[0110] The processor 1010 may be a microprocessor, a central processing unit, an application processor, etc. The processor 1010 may be connected to other components via an address bus, a control bus, and a data bus, etc. According to an embodiment, the processor 1010 may also be connected to an expansion bus such as a peripheral component interconnect (PCI) bus.

[0111] The memory device 1020 may store data required for the operation of the electronic device 1000 . For example, the memory device 1020 may include a non-volatile memory such as an Erasable Programmable Read-Only Memory (EPROM) device, an Electrically Erasable Programmable Read-Only Memory (EEPROM) device, a flash memory device, a Phase Change Random Access Memory (PRAM) device, a Resistance Random Access Memory (RRAM) device, a Nano Floating Gate Memory (NFGM) device, a Polymer Random Access Memory (PoRAM) device, a Magnetic Random Access Memory (MRAM) device, a Ferroelectric Random Access Memory (FRAM) device, etc. and / or a dynamic random access memory (DRAM) device, a static random access memory (SRAM) device, etc. Memory) devices, mobile DRAM devices, etc.

[0112] The storage device 1030 may include a solid state drive (SSD), a hard disk drive (HDD), a CD-ROM, etc.

[0113] The input / output device 1040 may include input devices such as a keyboard, a keypad, a touch pad, a touch screen, a mouse, etc. and output devices such as a speaker, a printer, etc. According to an embodiment, the display device 1060 may also be included in the input / output device 1040 .

[0114] The power supply 1050 may supply power required for the operation of the electronic device 1000 .

[0115] The display device 1060 may be connected to other components via a bus or other communication links.

[0116] Industrial Applicability The present invention can be applied to a display device and a method for driving the display device. For example, the present invention can be applied to a mobile phone, a smart phone, a tablet computer, a television (TV), a digital television (TV), a three-dimensional television (3D TV), a personal computer, a home electronic device, a notebook computer, a personal digital assistant (PDA), a portable multimedia player (PMP), a digital camera, a music player, a portable game console, a navigator, etc.

[0117] The above description refers to the embodiments of the present invention, but a person having ordinary knowledge in the technical field to which the present invention belongs can understand that various modifications and changes can be made to the present invention without departing from the concept and scope of the present invention described in the claims.

Claims

1. A display device, characterized in that: include: Display panel, including pixels; A drive control unit receives input image data including an input grayscale from a host, and generates a data signal including an output grayscale based on the input image data; as well as a data driving unit, converting the data signal into a data voltage and providing the data voltage to the display panel, When the driving frequency of the display panel is changed from a high frequency to a low frequency, the output gray level of the first low-frequency frame having the low frequency is less than or equal to the input gray level.

2. The display device according to claim 1, wherein: The output grayscale of the first low-frequency frame is less than or equal to an output grayscale of the high-frequency frame having the high frequency.

3. The display device according to claim 1, wherein: When a frequency interval that is a difference between the high frequency and the low frequency is greater than or equal to a reference frequency interval, the output gray level of the first low frequency frame is less than the input gray level.

4. The display device according to claim 3, characterized in that When the frequency interval is smaller than the reference frequency interval, the output gray level of the first low-frequency frame is equal to the input gray level.

5. The display device according to claim 3, characterized in that When the input gray level changes, the reference frequency interval changes.

6. The display device according to claim 5, characterized in that When the input gray level decreases, the reference frequency interval decreases.

7. The display device according to claim 1, wherein: The larger the frequency interval as the difference between the high frequency and the low frequency, the larger the average brightness of the first low-frequency frame.

8. The display device according to claim 7, characterized in that The greater the difference between the average brightness of the first low-frequency frame and the target brightness corresponding to the input grayscale, the greater the compensation grayscale of the first low-frequency frame, wherein the compensation grayscale of the first low-frequency frame is the difference between the input grayscale and the output grayscale of the first low-frequency frame.

9. The display device according to claim 1, wherein: An output gray level of a second low-frequency frame having the low frequency is greater than or equal to the output gray level of the first low-frequency frame and less than or equal to the input gray level.

10. The display device according to claim 9, characterized in that In the first low-frequency frame and the second low-frequency frame, the output gray level gradually increases toward the input gray level.

11. A method for driving a display device, characterized in that: The steps include: receiving input image data including an input grayscale from a host, generating a data signal including an output grayscale based on the input image data; and converting the data signal into a data voltage and providing the data voltage to a display panel, When the driving frequency of the display panel is changed from a high frequency to a low frequency, the output gray level of the first low-frequency frame having the low frequency is less than or equal to the input gray level.

12. The method for driving a display device according to claim 11, wherein: The output grayscale of the first low-frequency frame is less than or equal to an output grayscale of the high-frequency frame having the high frequency.

13. The method for driving a display device according to claim 11, wherein: When a frequency interval that is a difference between the high frequency and the low frequency is greater than or equal to a reference frequency interval, the output gray level of the first low frequency frame is less than the input gray level.

14. The method for driving a display device according to claim 13, wherein: When the frequency interval is smaller than the reference frequency interval, the output gray level of the first low-frequency frame is equal to the input gray level.

15. The method for driving a display device according to claim 13, wherein: When the input gray level changes, the reference frequency interval changes.

16. The method for driving a display device according to claim 15, wherein: When the input gray level decreases, the reference frequency interval decreases.

17. The method for driving a display device according to claim 11, wherein: The larger the frequency interval as the difference between the high frequency and the low frequency, the larger the average brightness of the first low-frequency frame.

18. The method for driving a display device according to claim 17, wherein: The greater the difference between the average brightness of the first low-frequency frame and the target brightness corresponding to the input grayscale, the greater the compensation grayscale of the first low-frequency frame, wherein the compensation grayscale of the first low-frequency frame is the difference between the input grayscale and the output grayscale of the first low-frequency frame.

19. The method for driving a display device according to claim 11, wherein: An output gray level of a second low-frequency frame having the low frequency is greater than or equal to the output gray level of the first low-frequency frame, and less than or equal to the input gray level.

20. The method for driving a display device according to claim 19, wherein: In the first low-frequency frame and the second low-frequency frame, the output gray level gradually increases toward the input gray level.

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