Display Devices

Abstract

A display device is provided, the display device comprising: a display panel 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; and a power supply voltage generator configured to generate a power supply voltage and output the power supply voltage so that an image is displayed on the display panel. The power supply voltage has a response speed that varies according to the input image data.

Description

Technical Field

[0001] Exemplary embodiments of the inventive concept relate to a display device and a method of driving a display panel using the same. More specifically, exemplary embodiments of the inventive concept relate to a display device using a power supply voltage having a response speed based on input image data and a method of driving a display panel using the same. Background Art

[0002] A display device generally includes a display panel and a display panel driver. For example, a typical display panel includes a plurality of gate lines, a plurality of data lines intersecting the plurality of gate lines, and a plurality of pixels connected to the gate lines and the data lines. The display panel driver includes a gate driver connected to the plurality of gate lines, a data driver connected to the plurality of data lines, and a power supply voltage generator connected to the plurality of pixels. The gate driver outputs a gate signal to the gate lines. The data driver outputs a data voltage to the data lines. The power supply voltage generator outputs a power supply voltage to the pixels.

[0003] When the display panel displays a high grayscale pattern such as a full white pattern, the peak current used to drive the display panel may increase beyond the threshold level, and the display device may not operate normally. Therefore, when the peak current increases beyond the threshold level, the input image data may be reduced to reduce the peak current.

[0004] However, an operation timing for reducing input image data may not coincide with a reduction timing of a power supply voltage applied to the display panel, and image flickering may occur. Summary of the invention

[0005] According to an exemplary embodiment of the inventive concept, a display device includes: a display panel 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; and a power supply voltage generator configured to generate a power supply voltage and output the power supply voltage so that an image is displayed on the display panel. The power supply voltage has a response speed that varies according to the input image data.

[0006] In an exemplary embodiment of the inventive concept, when the brightness of a current frame of input image data is equal to or less than the brightness of a previous frame of input image data, the power supply voltage has a first response speed. When the brightness of the current frame of input image data is greater than the brightness of the previous frame of input image data, the power supply voltage has a second response speed. The second response speed is different from the first response speed.

[0007] In an exemplary embodiment of the present inventive concept, the second response speed is slower than the first response speed.

[0008] In an exemplary embodiment of the inventive concept, the brightness of the current frame of the input image data is determined as the sum of the grayscale data of the current frame of the input image data corresponding to the entire area of ​​the display panel. The brightness of the previous frame of the input image data is determined as the sum of the grayscale data of the previous frame of the input image data corresponding to the entire area of ​​the display panel.

[0009] In an exemplary embodiment of the present invention, the display device also includes: a data analyzer configured to analyze input image data, determine whether the brightness of a current frame of the input image data is greater than the brightness of a previous frame of the input image data, and generate a selection signal indicating whether the brightness of the current frame of the input image data is greater than the brightness of the previous frame of the input image data; and a time constant selector configured to determine the time constant of the power supply voltage in response to the selection signal.

[0010] In an exemplary embodiment of the inventive concept, the display device further includes a driving controller configured to control an operation of the gate driver and an operation of the data driver. The driving controller includes a data analyzer and a time constant selector.

[0011] In an exemplary embodiment of the inventive concept, a power supply voltage generator includes a data analyzer and a time constant selector.

[0012] In an exemplary embodiment of the present inventive concept, a time constant selector includes: a first switch configured to receive a selection signal from a data analyzer; a first time constant circuit connected to the first switch; a second switch configured to receive a selection signal from the data analyzer; and a second time constant circuit connected to the second switch.

[0013] In an exemplary embodiment of the present inventive concept, the first time constant circuit includes a first resistor connected to the first switch and a first capacitor connected in parallel with the first resistor. The second time constant circuit includes a second resistor connected to the second switch and a second capacitor connected in parallel with the second resistor.

[0014] In an exemplary embodiment of the inventive concept, when the brightness of a current frame of input image data is equal to or less than the brightness of a previous frame of input image data, the first switch is turned on, and the power supply voltage generator is connected to the first time constant circuit through the first switch. When the brightness of the current frame of input image data is greater than the brightness of the previous frame of input image data, the second switch is turned on, and the power supply voltage generator is connected to the second time constant circuit through the second switch. The product of the resistance of the second resistor and the capacitance of the second capacitor is greater than the product of the resistance of the first resistor and the capacitance of the first capacitor.

[0015] In an exemplary embodiment of the present invention, a time constant selector includes: a first switch configured to receive a selection signal from a data analyzer; a first time constant circuit connected to the first switch; a second switch configured to receive a selection signal from the data analyzer; a second time constant circuit connected to the second switch; a third switch configured to receive a selection signal from the data analyzer; and a third time constant circuit connected to the third switch.

[0016] In an exemplary embodiment of the inventive concept, when the brightness of a current frame of input image data is equal to or less than the brightness of a previous frame of input image data, the first switch is turned on, and the power supply voltage generator is connected to the first time constant circuit through the first switch. When the brightness of the current frame of input image data is greater than the brightness of the previous frame of input image data, and when the difference between the brightness of the current frame of input image data and the brightness of the previous frame of input image data is equal to or less than a threshold value, the second switch is turned on, and the power supply voltage generator is connected to the second time constant circuit through the second switch. When the brightness of the current frame of input image data is greater than the brightness of the previous frame of input image data, and when the difference between the brightness of the current frame of input image data and the brightness of the previous frame of input image data is greater than a threshold value, the third switch is turned on, and the power supply voltage generator is connected to the third time constant circuit through the third switch.

[0017] In an exemplary embodiment of the present inventive concept, the display panel includes an organic light emitting diode, and a power supply voltage is output to the organic light emitting diode.

[0018] According to an exemplary embodiment of the present invention, a method of driving a display panel includes: outputting a gate signal to the display panel; outputting a data voltage corresponding to input image data to the display panel; generating a power supply voltage having a response speed that varies according to the input image data; and outputting the power supply voltage to pixels of the display panel.

[0019] In an exemplary embodiment of the inventive concept, when the brightness of a current frame of input image data is equal to or less than the brightness of a previous frame of input image data, the power supply voltage has a first response speed. When the brightness of the current frame of input image data is greater than the brightness of the previous frame of input image data, the power supply voltage has a second response speed. The second response speed is different from the first response speed.

[0020] In an exemplary embodiment of the present inventive concept, the second response speed is slower than the first response speed.

[0021] In an exemplary embodiment of the inventive concept, the brightness of a current frame of input image data is determined as the sum of grayscale data of the current frame of input image data corresponding to the entire area of ​​the display panel. The brightness of a previous frame of input image data is determined as the sum of grayscale data of the previous frame of input image data corresponding to the entire area of ​​the display panel.

[0022] In an exemplary embodiment of the present invention, the method also includes: analyzing input image data; using a data analyzer to determine whether the brightness of a current frame of the input image data is greater than the brightness of a previous frame of the input image data, and generating a selection signal indicating whether the brightness of the current frame of the input image data is greater than the brightness of the previous frame of the input image data; and using a time constant selector to determine the time constant of the power supply voltage in response to the selection signal.

[0023] In an exemplary embodiment of the present inventive concept, a time constant selector includes: a first switch configured to receive a selection signal from a data analyzer; a first time constant circuit connected to the first switch; a second switch configured to receive a selection signal from the data analyzer; and a second time constant circuit connected to the second switch.

[0024] In an exemplary embodiment of the present inventive concept, the first time constant circuit includes a first resistor connected to the first switch and a first capacitor connected in parallel with the first resistor. The second time constant circuit includes a second resistor connected to the second switch and a second capacitor connected in parallel with the second resistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other features of the present inventive concept will become more apparent by describing in detail exemplary embodiments of the present inventive concept with reference to the accompanying drawings, in which:

[0026] Figure 1 is a block diagram illustrating a display device according to an exemplary embodiment of the inventive concept;

[0027] Figure 2 It shows Figure 1 A circuit diagram of a pixel of a display panel;

[0028] Figure 3 It shows Figure 1 Block diagram of a drive controller and supply voltage generator;

[0029] Figure 4 It shows Figure 3 Circuit diagram of the time constant selector;

[0030] Figure 5A It shows that when Figure 1A graph showing the brightness of an image when a power supply voltage generator of the embodiment of the present invention sets the response speed of the power supply voltage to be high regardless of the increase and decrease of the brightness;

[0031] Figure 5B It shows that when Figure 1 A graph showing the brightness of an image when a power supply voltage generator of the embodiment of the present invention sets the response speed of the power supply voltage to be low regardless of the increase and decrease of the brightness;

[0032] Figure 5C It shows that when Figure 1 The power supply voltage generator sets the response speed of the power supply voltage to a curve graph of the brightness of the image when it changes according to the increase and decrease of the brightness;

[0033] Figure 6 is a block diagram illustrating a power supply voltage generator of a display device according to an exemplary embodiment of the inventive concept;

[0034] Figure 7 is a circuit diagram illustrating a time constant selector according to an exemplary embodiment of the inventive concept; and

[0035] Figure 8 It shows Figure 7 Table of the operation of the time constant selector. DETAILED DESCRIPTION

[0036] Hereinafter, exemplary embodiments of the inventive concept will be described in detail with reference to the accompanying drawings.

[0037] Figure 1 is a block diagram illustrating a display device according to an exemplary embodiment of the inventive concept.

[0038] Reference Figure 1 The display device includes a display panel 100 and a display panel driver. The display panel driver includes a driving controller 200, a gate driver 300, a gamma reference voltage generator 400, a data driver 500, and a power supply voltage generator 600.

[0039] For example, the driving controller 200 and the data driver 500 may be integrally formed. For example, the driving controller 200, the gamma reference voltage generator 400 and the data driver 500 may be integrally formed. For example, the driving controller 200, the gate driver 300, the gamma reference voltage generator 400 and the data driver 500 may be integrally formed.

[0040] The display panel 100 includes a display area and a peripheral area adjacent to the display area. For example, the peripheral area may at least partially surround the display area.

[0041] For example, the display panel 100 may be an organic light emitting diode display panel including organic light emitting diodes. However, the inventive concept is not limited thereto. For example, the display panel 100 may be a liquid crystal display panel.

[0042] The display panel 100 includes 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 extend in a first direction D1, and the data lines DL extend in a second direction D2 crossing the first direction D1.

[0043] The driving controller 200 receives input image data IMG and an input control signal CONT from an external device. The input image data IMG may include red image data, green image data, and blue image data. For example, the input image data IMG may include white image data. For 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 master clock signal and a data enable signal. The input control signal CONT may also include a vertical synchronization signal and a horizontal synchronization signal.

[0044] The driving controller 200 generates 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 input image data IMG and an input control signal CONT.

[0045] The driving controller 200 generates a first control signal CONT1 for controlling the operation of the gate driver 300 based on the input control signal CONT, and outputs the first control signal CONT1 to the gate driver 300. The first control signal CONT1 may include a vertical start signal and a gate clock signal.

[0046] The driving controller 200 generates a second control signal CONT2 for controlling the operation of the data driver 500 based on the input control signal CONT, and outputs the second control signal CONT2 to the data driver 500. The second control signal CONT2 may include a horizontal start signal and a load signal.

[0047] The driving controller 200 generates a data signal DATA based on the input image data IMG. The driving controller 200 outputs the data signal DATA to the data driver 500.

[0048] The driving controller 200 generates a third control signal CONT3 for controlling the operation of the gamma reference voltage generator 400 based on the input control signal CONT, and outputs the third control signal CONT3 to the gamma reference voltage generator 400 .

[0049] The driving controller 200 generates a fourth control signal CONT4 for controlling the operation of the power voltage generator 600 based on the input image data IMG and / or the input control signal CONT, and outputs the fourth control signal CONT4 to the power voltage generator 600 .

[0050] In response to the first control signal CONT1 generated from the driving controller 200, the gate driver 300 generates a gate signal for driving the gate line GL. The gate driver 300 outputs the gate signal to the gate line GL. For example, the gate driver 300 may sequentially output the gate signal to the gate line GL. For example, the gate line GL may include a write gate line for transmitting a write gate signal to a pixel. In addition, the gate line GL may include an initialization gate line for transmitting an initialization gate signal to a pixel.

[0051] The gamma reference voltage generator 400 generates a gamma reference voltage VGREF in response to a third control signal CONT3 generated from the driving controller 200. The gamma reference voltage generator 400 provides the gamma reference voltage VGREF to the data driver 500. The gamma reference voltage VGREF has a value corresponding to a predetermined voltage level of the data signal DATA.

[0052] In an exemplary embodiment of the inventive concept, the gamma reference voltage generator 400 may be provided in the driving controller 200 , or in the data driver 500 .

[0053] The data driver 500 receives the second control signal CONT2 and the data signal DATA from the driving controller 200. In addition, the data driver 500 receives the gamma reference voltage VGREF from the gamma reference voltage generator 400. The data driver 500 converts the data signal DATA into a data voltage of an analog type using the gamma reference voltage VGREF. The data driver 500 outputs the data voltage to the data line DL.

[0054] The power supply voltage generator 600 may generate a power supply voltage to drive the display device. For example, the power supply voltage generator 600 may generate a gate power supply voltage to drive the gate driver 300. For example, the power supply voltage generator 600 may generate a data power supply voltage to drive the data driver 500. For example, the power supply voltage generator 600 may generate a common voltage applied to the display panel 100. For example, the power supply voltage generator 600 may generate a power supply voltage output to an organic light emitting diode of the display panel 100. For example, the power supply voltage generator 600 may generate a high power supply voltage (or simply referred to as a power supply voltage) ELVDD output to an organic light emitting diode of the display panel 100. For example, the power supply voltage generator 600 may generate a high power supply voltage (or simply referred to as a power supply voltage) ELVDD output to an organic light emitting diode of the display panel 100. Figure 2The low power supply voltage ELVSS in.

[0055] Figure 2 It shows Figure 1 1 is a circuit diagram of a pixel of the display panel 100.

[0056] Reference Figure 1 and Figure 2 , the display panel 100 may include a plurality of pixels arranged in a matrix form. The pixel may include an organic light emitting diode OL. Light emitted by the organic light emitting diode OL is adjusted based on the data voltage VD.

[0057] For example, the pixel may include a first switching element T1, a second switching element T2, a third switching element T3, a capacitor C, and an organic light emitting diode OL.

[0058] The first switching element T1 may include a gate electrode to which a write gate signal GS is applied, a source electrode to which a data voltage VD is applied, and a drain electrode connected to the gate electrode of the second switching element T2. For example, in response to the received write gate signal GS, the data voltage VD may be transmitted from the first switching element T1 to the capacitor C and the second switching element T2.

[0059] The second switching element T2 may include a gate electrode connected to the drain electrode of the first switching element T1, a source electrode to which the high power supply voltage ELVDD is applied, and a drain electrode connected to the anode electrode of the organic light emitting diode OL. For example, in response to the data voltage VD received by the gate electrode of the second switching element T2, the high power supply voltage ELVDD may be transmitted from the second switching element T2 to the anode electrode of the organic light emitting diode OL.

[0060] The third switching element T3 may include a gate electrode to which the initialization gate signal GI is applied, a source electrode to which the initialization voltage VI is applied, and a drain electrode connected to the anode electrode of the organic light emitting diode OL.

[0061] The capacitor C may include a first electrode connected to the gate electrode of the second switching element T2 and a second electrode connected to the drain electrode of the second switching element T2 .

[0062] The organic light emitting diode OL may include an anode electrode connected to the drain electrode of the second switching element T2 and a cathode electrode to which the low power voltage ELVSS is applied.

[0063] The power supply voltage generator 600 may generate a high power supply voltage ELVDD having a response speed that varies according to input image data IMG and output the high power supply voltage ELVDD to the pixels.

[0064] The present invention is not limited to Figure 2The inventive concept may be applied to other pixel circuits to which a high power supply voltage ELVDD is applied.

[0065] Figure 3 It shows Figure 1 1 is a block diagram of a driving controller 200 and a power supply voltage generator 600. Figure 4 It shows Figure 3 2 is a circuit diagram of the time constant selector 240.

[0066] Reference Figures 1 to 4 , the power voltage generator 600 may generate the power voltage ELVDD having a response speed that varies according to the input image data IMG. When the brightness of the current frame of the input image data IMG is equal to or less than the brightness of the previous frame of the input image data IMG, the power voltage ELVDD may have a first response speed. When the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG, the power voltage ELVDD may have a second response speed different from the first response speed. The second response speed may be slower than the first response speed.

[0067] In the present exemplary embodiment, the driving controller 200 may include a data analyzer 220 and a time constant selector 240 .

[0068] The data analyzer 220 analyzes the input image data IMG. The data analyzer 220 may determine whether the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG. The data analyzer 220 may generate a selection signal SEL indicating whether the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG.

[0069] The data analyzer 220 may determine the brightness of the current frame of the input image data IMG as the sum of grayscale data of the current frame of the input image data IMG corresponding to the entire area of ​​the display panel 100 .

[0070] The data analyzer 220 may determine the brightness of the previous frame of the input image data IMG as the sum of grayscale data of the previous frame of the input image data IMG corresponding to the entire area of ​​the display panel 100 .

[0071] For example, the data analyzer 220 may be physically implemented by electronic circuits (or optical circuits) (such as logic circuits, discrete components, microprocessors, hard-wired circuits, memory elements, wiring connections, etc.) that may be formed using semiconductor-based manufacturing techniques or other manufacturing techniques. The data analyzer 220 may be programmed using software (e.g., microcode) to perform the various functions discussed herein, and may be optionally driven by firmware and / or software. In addition, the data analyzer 220 may be implemented by dedicated hardware, or may be implemented as a combination of dedicated hardware for performing some functions and a processor (e.g., one or more programmed microprocessors and associated circuits) for performing other functions.

[0072] The time constant selector 240 may determine a time constant of the power supply voltage ELVDD in response to a selection signal SEL.

[0073] In the present exemplary embodiment, the time constant selector 240 may include two time constant circuits. For example, the time constant selector 240 may include a first switch SW1, a first time constant circuit connected to the first switch SW1, a second switch SW2, and a second time constant circuit connected to the second switch SW2.

[0074] For example, the first selection signal SEL1 may be applied to the first switch SW1 , and the second selection signal SEL2 may be applied to the second switch SW2 .

[0075] For example, when the brightness of the current frame of the input image data IMG is equal to or less than the brightness of the previous frame of the input image data IMG, the data analyzer 220 may activate and output the first selection signal SEL1 and disable the second selection signal SEL2. Therefore, when the brightness of the current frame of the input image data IMG is equal to or less than the brightness of the previous frame of the input image data IMG, the first switch SW1 is turned on, so that the power supply voltage generator 600 is connected to the first time constant circuit through the first switch SW1, and the power supply voltage ELVDD may have a first response speed. When the first switch SW1 is turned on, the second switch SW2 may be turned off.

[0076] For example, when the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG, the data analyzer 220 may activate the second selection signal SEL2 and disable the first selection signal SEL1. Therefore, when the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG, the second switch SW2 is turned on, so that the power supply voltage generator 600 is connected to the second time constant circuit through the second switch SW2, and the power supply voltage ELVDD may have a second response speed. When the second switch SW2 is turned on, the first switch SW1 may be turned off.

[0077] For example, the first time constant circuit may include a first resistor R1 connected to the first switch SW1 and a first capacitor C1 connected in parallel to the first resistor R1 .

[0078] For example, the second time constant circuit may include a second resistor R2 connected to the second switch SW2 and a second capacitor C2 connected in parallel to the second resistor R2.

[0079] The time constant of the first time constant circuit may be determined as the product of the resistance of the first resistor R1 and the capacitance of the first capacitor C1. The time constant of the second time constant circuit may be determined as the product of the resistance of the second resistor R2 and the capacitance of the second capacitor C2.

[0080] The time constant of the second time constant circuit may be greater than the time constant of the first time constant circuit. Therefore, when the power supply voltage generator 600 is connected to the second time constant circuit through the second switch SW2, the response speed of the power supply voltage ELVDD may become slower. When the power supply voltage generator 600 is connected to the first time constant circuit through the first switch SW1, the response speed of the power supply voltage ELVDD may become faster. For example, the first response speed may be faster than the second response speed.

[0081] Figure 5A It shows that when Figure 1 Graph showing brightness of an image when the power supply voltage generator of FIG. 1 sets the response speed of the power supply voltage ELVDD to be high regardless of increase and decrease in brightness. Figure 5B It shows that when Figure 1 Graph showing the brightness of an image when the power supply voltage generator of FIG. 1 sets the response speed of the power supply voltage ELVDD to be low regardless of increase and decrease in brightness. Figure 5C It shows that when Figure 1 The power supply voltage generator sets the response speed of the power supply voltage ELVDD to a graph of the brightness of an image when it changes according to the increase and decrease of the brightness.

[0082] Reference Figures 1 to 5C , when the image of the input image data IMG changes from a low grayscale image to a high grayscale image, the driving controller 200 may operate a net power control operation so that the peak current of the driving current of the display panel 100 does not increase rapidly.

[0083] When the driving controller 200 determines that the image of the input image data IMG changes from a low grayscale image to a high grayscale image, the driving controller 200 may reduce the level of the input image data IMG. For example, when a 1% area of ​​the display panel 100 exhibits a maximum grayscale and other areas of the display panel 100 exhibit a minimum grayscale, the 1% area of ​​the display panel 100 exhibiting the maximum grayscale may exhibit a first brightness through a first voltage. When a 100% area of ​​the display panel 100 exhibits a maximum grayscale, a 100% area of ​​the display panel 100 may exhibit a second brightness that is smaller than the first brightness through a second voltage that is smaller than the first voltage.

[0084] The driving controller 200 may operate a net power control operation based on the current frame data of the input image data IMG. Figure 5A BLACK in the image) to a high grayscale image (for example, Figure 5A When the net power control operation is not fast enough to be consistent with the operation timing of the input image data IMG, for example, the display panel 100 may show higher brightness in the initial frame of the high grayscale image than in other frames because the net power control operation is not immediately applied.

[0085] exist Figure 5A In the embodiment, the response speed of the power supply voltage ELVDD can be set to be fast regardless of the increase and decrease of the brightness. Figure 5A , the input image data IMG represents a low grayscale image BLACK in the first to fourth frames F1 to F4 , represents a high grayscale image WHITE in the fifth to eighth frames F5 to F8 , and represents a low grayscale image BLACK in the ninth to twelfth frames F9 to F12 .

[0086] When the net power control operation is not fast enough, the fifth frame F5 may represent the first data voltage to which the net power control is not applied. Therefore, the display panel 100 may display highly enhanced brightness in the initial portion of the fifth frame F5.

[0087] In contrast, net power control is applied to the sixth frame F6 to the eighth frame F8, so that the sixth frame F6 to the eighth frame F8 may represent a second data voltage that is smaller than the first data voltage corresponding to the high grayscale image WHITE. Therefore, the brightness of the display panel 100 may be substantially stable in the sixth frame F6 to the eighth frame F8. For example, the slope of the brightness may be substantially linear.

[0088] For example, the highly enhanced brightness in the fifth frame F5 will be displayed to the user as a flash. When the low grayscale image BLACK and the high grayscale image WHITE are repeated, the highly enhanced brightness will be displayed to the user as a repeated flash.

[0089] exist Figure 5BIn the embodiment, the response speed of the power supply voltage ELVDD can be set to be slow regardless of the increase and decrease of the brightness. Figure 5B , the input image data IMG represents a low grayscale image BLACK in the first to fourth frames F1 to F4 , represents a high grayscale image WHITE in the fifth to eighth frames F5 to F8 , and represents a low grayscale image BLACK in the ninth to twelfth frames F9 to F12 .

[0090] When the net power control operation is not fast enough, the fifth frame F5 will show the first data voltage to which the net power control operation is not applied. However, the response speed of the power supply voltage ELVDD is Figure 5B The IR is set to slow so that the brightness of the display panel 100 is not highly enhanced in the initial portion of the fifth frame F5.

[0091] Since the response speed of the power supply voltage ELVDD is set to be slow, the brightness decreases slowly in the initial part of the ninth frame F9. Therefore, the ninth frame F9 may show a brightness higher than the expected brightness or the predetermined brightness, so that the higher brightness may be displayed to the user as image retention or image afterimage.

[0092] exist Figure 5C In the embodiment, the response speed of the power supply voltage ELVDD may vary according to the increase and decrease of the brightness. For example, when the brightness of the current frame of the input image data IMG is equal to or less than the brightness of the previous frame of the input image data IMG, the power supply voltage ELVDD has a first response speed. When the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG, the power supply voltage ELVDD has a second response speed that is slower than the first response speed. Figure 5C , the input image data IMG represents a low grayscale image BLACK in the first to fourth frames F1 to F4 , represents a high grayscale image WHITE in the fifth to eighth frames F5 to F8 , and represents a low grayscale image BLACK in the ninth to twelfth frames F9 to F12 .

[0093] When the net power control operation is not fast enough, the fifth frame F5 will show the first data voltage to which the net power control operation is not applied. However, the response speed of the power supply voltage ELVDD is Figure 5C The response speed may be set to be slow in the fifth frame F5 so that the brightness of the display panel 100 is not highly enhanced in the initial portion of the fifth frame F5. For example, in the fifth frame F5, the response speed may be set to the second response speed.

[0094] In addition, since the response speed of the power supply voltage ELVDD is Figure 5CIn the ninth frame F9, the response speed is set to fast (first response speed), and the brightness is rapidly reduced in the initial part of the ninth frame F9. For example, in the ninth frame F9, the response speed may be set to the first response speed. Therefore, image defects such as image sticking or image residue are not generated in the ninth frame F9.

[0095] According to the present exemplary embodiment, the input image data IMG may be analyzed, and the response speed of the power supply voltage ELVDD applied to the pixel may be adjusted according to the input image data IMG. When the brightness of the current frame of the input image data IMG is equal to or less than the brightness of the previous frame of the input image data IMG, the response speed of the power supply voltage ELVDD may be adjusted to increase and be relatively high. When the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG, the response speed of the power supply voltage ELVDD may be adjusted to decrease and be relatively low; for example, lower than the first response speed. Therefore, when the brightness of the current frame is greater than the brightness of the previous frame, flickering of the display panel 100 may be prevented. In addition, when the brightness of the current frame is equal to or less than the brightness of the previous frame, the high response speed of the power supply voltage ELVDD may be maintained. Therefore, the display quality of the display panel 100 may be improved.

[0096] Figure 6 is a block diagram illustrating a power supply voltage generator 600A of a display device according to an exemplary embodiment of the inventive concept.

[0097] The display device and the method of driving the display panel according to the present exemplary embodiment are similar to those of the reference 1 except that the data analyzer and the time constant selector are provided in the power supply voltage generator. Figures 1 to 5C The display device and the method of driving the display panel of the previously explained exemplary embodiments are substantially the same. Therefore, the same reference numerals may be used to represent the same as those in Figures 1 to 5C The components that are the same as or similar to those described in the previous exemplary embodiments may be described, and any repeated explanation regarding the above elements may be omitted.

[0098] Reference Figure 1 , Figure 2 as well as Figures 4 to 6 The display device includes a display panel 100 and a display panel driver. The display panel driver includes a driving controller 200, a gate driver 300, a gamma reference voltage generator 400, a data driver 500, and a power supply voltage generator 600A.

[0099] The power supply voltage generator 600A may generate a power supply voltage ELVDD having a response speed that varies according to the input image data IMG. When the brightness of the current frame of the input image data IMG is equal to or less than the brightness of the previous frame of the input image data IMG, the power supply voltage ELVDD may have a first response speed. When the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG, the power supply voltage ELVDD may have a second response speed different from the first response speed. For example, the second response speed may be slower than the first response speed.

[0100] In the present exemplary embodiment, the power supply voltage generator 600A may include a data analyzer 620 , a time constant selector 640 , and an ELVDD generator 660 .

[0101] The data analyzer 620 analyzes the input image data IMG. The data analyzer 620 may determine whether the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG. The data analyzer 620 may generate a selection signal SEL indicating whether the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG.

[0102] In this exemplary embodiment, the data analyzer 620 may receive the data signal DATA from the driving controller 200. The data analyzer 620 may analyze the data signal DATA corresponding to the input image data IMG to determine whether the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG.

[0103] The data analyzer 620 may determine the brightness of the current frame of the input image data IMG as the sum of grayscale data of the current frame of the input image data IMG corresponding to the entire area of ​​the display panel 100 .

[0104] The data analyzer 620 may determine the brightness of the previous frame of the input image data IMG as the sum of grayscale data of the previous frame of the input image data IMG corresponding to the entire area of ​​the display panel 100 .

[0105] The time constant selector 640 may determine a time constant of the power supply voltage ELVDD in response to a selection signal SEL.

[0106] In the present exemplary embodiment, the time constant selector 640 may include two time constant circuits. For example, the time constant selector 640 may include a first switch SW1, a first time constant circuit connected to the first switch SW1, a second switch SW2, and a second time constant circuit connected to the second switch SW2.

[0107] The ELVDD generator 660 may be connected to the first time constant circuit through the first switch SW1 or connected to the second time constant circuit through the second switch SW2 .

[0108] The time constant of the second time constant circuit may be greater than the time constant of the first time constant circuit. Therefore, when the ELVDD generator 660 is connected to the second time constant circuit through the second switch SW2, the response speed of the power supply voltage ELVDD may be slowed down. When the ELVDD generator 660 is connected to the first time constant circuit through the first switch SW1, the response speed of the power supply voltage ELVDD may be fast. For example, the response speed of the power supply voltage ELVDD corresponding to the first time constant circuit may be faster than the response speed of the power supply voltage ELVDD corresponding to the second time constant circuit.

[0109] According to the present exemplary embodiment, the input image data IMG can be analyzed, and the response speed of the power supply voltage ELVDD applied to the pixel can be adjusted according to the input image data IMG. When the brightness of the current frame of the input image data IMG is equal to or less than the brightness of the previous frame of the input image data IMG, the response speed of the power supply voltage ELVDD can be adjusted to increase. For example, the response speed of the power supply voltage ELVDD can be relatively high. When the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG, the response speed of the power supply voltage ELVDD can be adjusted to decrease. For example, the response speed of the power supply voltage ELVDD can be relatively low. Therefore, when the brightness of the current frame increases to be greater than the brightness of the previous frame, flickering can be prevented. In addition, when the brightness of the current frame does not increase to be greater than the brightness of the previous frame, the high response speed of the power supply voltage ELVDD can be maintained. Therefore, the display quality of the display panel 100 can be improved.

[0110] Figure 7 is a circuit diagram illustrating a time constant selector 240B according to an exemplary embodiment of the inventive concept. Figure 8 It shows Figure 7 Table of the operation of the time constant selector 240B.

[0111] In addition to the structure and operation of the time constant selector, the display device and the method of driving the display panel according to the present exemplary embodiment are similar to those of the reference Figures 1 to 5C The display device and the method of driving the display panel of the previously explained exemplary embodiments are substantially the same. Therefore, the same reference numerals may be used to represent the same as those in Figures 1 to 5C The components that are the same as or similar to those described in the previous exemplary embodiments may be described, and any repeated explanation regarding the above elements may be omitted.

[0112] Reference Figures 1 to 3 , FIG. 5A to FIG. 5C , Figure 7 and Figure 8 The display device includes a display panel 100 and a display panel driver. The display panel driver includes a driving controller 200, a gate driver 300, a gamma reference voltage generator 400, a data driver 500, and a power supply voltage generator 600.

[0113] The power supply voltage generator 600 may generate a power supply voltage ELVDD having a response speed that varies according to the input image data IMG. When the brightness of the current frame of the input image data IMG is equal to or less than the brightness of the previous frame of the input image data IMG, the power supply voltage ELVDD may have a first response speed. When the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG, the power supply voltage ELVDD may have a second response speed that is different from the first response speed. For example, the second response speed may be slower than the first response speed. In this exemplary embodiment, when the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG, the response speed of the power supply voltage ELVDD may vary according to the difference between the brightness of the previous frame of the input image data IMG and the brightness of the current frame of the input image data IMG.

[0114] In this exemplary embodiment, the driving controller 200 may include a data analyzer 220 and a time constant selector 240B. In another embodiment, the data analyzer and the time constant selector may be provided in the power supply voltage generator 600. For example, the power supply voltage generator 600 may include a Figure 6 The data analyzer 620 and the time constant selector 640 are shown in FIG.

[0115] The data analyzer 220 analyzes the input image data IMG. The data analyzer 220 may determine whether the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG. The data analyzer 220 may generate a selection signal SEL indicating whether the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG.

[0116] The time constant selector 240B may determine the time constant of the power supply voltage ELVDD in response to the selection signal SEL.

[0117] In the present exemplary embodiment, the time constant selector 240B may include five time constant circuits; however, the inventive concept is not limited thereto and may include less than five time constant circuits or more than five time constant circuits. When the brightness of the current frame of the input image data IMG is equal to or less than the brightness of the previous frame of the input image data IMG, the first time constant circuit may be connected to the power supply voltage generator 600 through the first switch SW1. When the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG, one of the time constant circuits other than the first time constant circuit may be connected to the power supply voltage generator 600 through their respective switches (e.g., SW2-SW5) according to the difference between the brightness of the current frame of the input image data IMG and the brightness of the previous frame of the input image data IMG.

[0118] Although the time constant selector 240B includes five time constant circuits, the inventive concept is not limited thereto.

[0119] For example, the time constant selector 240B may include a first switch SW1 to which a selection signal SEL can be applied, a first time constant circuit connected to the first switch SW1, a second switch SW2 to which the selection signal SEL can be applied, a second time constant circuit connected to the second switch SW2, a third switch SW3 to which the selection signal SEL can be applied, a third time constant circuit connected to the third switch SW3, a fourth switch SW4 to which the selection signal SEL can be applied, a fourth time constant circuit connected to the fourth switch SW4, a fifth switch SW5 to which the selection signal SEL can be applied, and a fifth time constant circuit connected to the fifth switch SW5.

[0120] For example, the first selection signal SEL1 may be applied to the first switch SW1, the second selection signal SEL2 may be applied to the second switch SW2, the third selection signal SEL3 may be applied to the third switch SW3, the fourth selection signal SEL4 may be applied to the fourth switch SW4, and the fifth selection signal SEL5 may be applied to the fifth switch SW5.

[0121] For example, when the brightness of the current frame of the input image data IMG is equal to or less than the brightness of the previous frame of the input image data IMG, the data analyzer 220 may activate and output the first selection signal SEL1 and disable the second selection signal SEL2 to the fifth selection signal SEL5. Therefore, when the brightness of the current frame of the input image data IMG is equal to or less than the brightness of the previous frame of the input image data IMG, the first switch SW1 is turned on, so that the power supply voltage generator 600 is connected to the first time constant circuit through the first switch SW1, and the power supply voltage ELVDD may have a first response speed.

[0122] For example, when the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG, the data analyzer 220 can activate and output one of the second to fifth selection signals SEL2 to SEL5 and disable the first selection signal SEL1 according to the difference between the brightness of the current frame of the input image data IMG and the brightness of the previous frame of the input image data IMG.

[0123] Therefore, when the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG, one of the second to fifth switches SW2 to SW5 is turned on, so that the power supply voltage ELVDD can have one of the second to fifth response speeds, each response speed corresponding to their respective time constant circuits.

[0124] For example, the first time constant circuit may include a first resistor R1 connected to the first switch SW1 and a first capacitor C1 connected in parallel with the first resistor R1. For example, the second time constant circuit may include a second resistor R2 connected to the second switch SW2 and a second capacitor C2 connected in parallel with the second resistor R2. For example, the third time constant circuit may include a third resistor R3 connected to the third switch SW3 and a third capacitor C3 connected in parallel with the third resistor R3. For example, the fourth time constant circuit may include a fourth resistor R4 connected to the fourth switch SW4 and a fourth capacitor C4 connected in parallel with the fourth resistor R4. For example, the fifth time constant circuit may include a fifth resistor R5 connected to the fifth switch SW5 and a fifth capacitor C5 connected in parallel with the fifth resistor R5.

[0125] The time constant of the first time constant circuit may be determined as the product of the resistance of the first resistor R1 and the capacitance of the first capacitor C1. The time constant of the second time constant circuit may be determined as the product of the resistance of the second resistor R2 and the capacitance of the second capacitor C2. The time constant of the third time constant circuit may be determined as the product of the resistance of the third resistor R3 and the capacitance of the third capacitor C3. The time constant of the fourth time constant circuit may be determined as the product of the resistance of the fourth resistor R4 and the capacitance of the fourth capacitor C4. The time constant of the fifth time constant circuit may be determined as the product of the resistance of the fifth resistor R5 and the capacitance of the fifth capacitor C5.

[0126] The time constant of the second time constant circuit may be greater than the time constant of the first time constant circuit. Therefore, when the power supply voltage generator 600 is connected to the second time constant circuit through the second switch SW2, the response speed of the power supply voltage ELVDD is slower than the response speed of the power supply voltage ELVDD generated when the power supply voltage generator 600 is connected to the first time constant circuit through the first switch SW1.

[0127] The time constant of the third time constant circuit may be greater than the time constant of the second time constant circuit. Therefore, when the power supply voltage generator 600 is connected to the third time constant circuit through the third switch SW3, the response speed of the power supply voltage ELVDD is slower than the response speed of the power supply voltage ELVDD generated when the power supply voltage generator 600 is connected to the second time constant circuit through the second switch SW2.

[0128] The time constant of the fourth time constant circuit may be greater than the time constant of the third time constant circuit. Therefore, when the power supply voltage generator 600 is connected to the fourth time constant circuit through the fourth switch SW4, the response speed of the power supply voltage ELVDD is slower than the response speed of the power supply voltage ELVDD generated when the power supply voltage generator 600 is connected to the third time constant circuit through the third switch SW3.

[0129] The time constant of the fifth time constant circuit may be greater than the time constant of the fourth time constant circuit. Therefore, when the power supply voltage generator 600 is connected to the fifth time constant circuit through the fifth switch SW5, the response speed of the power supply voltage ELVDD is slower than the response speed of the power supply voltage ELVDD generated when the power supply voltage generator 600 is connected to the fourth time constant circuit through the fourth switch SW4.

[0130] For example, in Figure 8 In the embodiment of the present invention, when the brightness of the previous frame is 0% and the brightness of the current frame is 25%, the power supply voltage generator 600 is connected to the second time constant circuit, so that the transient response time of the power supply voltage ELVDD can be 20ms. When the brightness of the previous frame is 0% and the brightness of the current frame is 50%, the power supply voltage generator 600 is connected to the third time constant circuit, so that the transient response time of the power supply voltage ELVDD can be 30ms. When the brightness of the previous frame is 0% and the brightness of the current frame is 75%, the power supply voltage generator 600 is connected to the fourth time constant circuit, so that the transient response time of the power supply voltage ELVDD can be 40ms. When the brightness of the previous frame is 0% and the brightness of the current frame is 100%, the power supply voltage generator 600 is connected to the fifth time constant circuit, so that the transient response time of the power supply voltage ELVDD can be 50ms.

[0131] For example, the selective connection between the power supply voltage generator 600 and the second to fifth time constant circuits may be determined by a threshold value of the difference between the brightness of the previous frame and the brightness of the current frame. For example, the selective connection between the power supply voltage generator 600 and one of the second to fifth time constant circuits may be determined by whether the difference between the brightness of the previous frame and the brightness of the current frame is equal to or less than a threshold value.

[0132] According to the present exemplary embodiment, the input image data IMG can be analyzed, and the response speed of the power supply voltage ELVDD applied to the pixel can be adjusted according to the input image data IMG. When the brightness of the current frame of the input image data IMG is equal to or less than the brightness of the previous frame of the input image data IMG, the response speed of the power supply voltage ELVDD can be adjusted to increase and be relatively high. When the brightness of the current frame of the input image data IMG is greater than the brightness of the previous frame of the input image data IMG, the response speed of the power supply voltage ELVDD can be adjusted to decrease and be relatively low. Therefore, when the brightness of the current frame increases to be greater than the brightness of the previous frame, the flicker of the display panel can be prevented. In addition, when the brightness of the current frame does not increase to be greater than the brightness of the previous frame, the high response speed of the power supply voltage ELVDD can be maintained. Therefore, the display quality of the display panel 100 can be improved.

[0133] According to exemplary embodiments of the inventive concept, a display device and a method of driving a display panel using the display device may adjust a response speed of a power voltage applied to a pixel according to input image data, so that display quality of the display panel may be improved.

[0134] The foregoing is an illustration of the inventive concept and is not to be construed as a limitation of the inventive concept. Although some exemplary embodiments of the inventive concept have been described, it will be readily understood by those of ordinary skill in the art that various modifications in form and detail can be made in the exemplary embodiments without departing from the spirit and scope of the inventive concept. Therefore, all such modifications are intended to be included in the spirit and scope of the inventive concept.

Claims

1. A display device, the display device include: a display panel 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; as well as a power supply voltage generator configured to generate a power supply voltage and output the power supply voltage so that an image is displayed on the display panel, wherein the power supply voltage has a response speed that varies according to the input image data, When the brightness of the current frame of the input image data is equal to or less than the brightness of the previous frame of the input image data, the power supply voltage has a first response speed. wherein, when the brightness of the current frame of the input image data is greater than the brightness of the previous frame of the input image data, the power supply voltage has a second response speed, wherein the second response speed is slower than the first response speed, and Wherein, when the brightness of the current frame of the input image data is greater than the brightness of the previous frame of the input image data, the second response speed of the power supply voltage changes according to the difference between the brightness of the previous frame of the input image data and the brightness of the current frame of the input image data.

2. The display device according to claim 1, in, The brightness of the current frame of the input image data is determined as the sum of grayscale data of the current frame of the input image data corresponding to the entire area of ​​the display panel, and The brightness of the previous frame of the input image data is determined as the sum of grayscale data of the previous frame of the input image data corresponding to the entire area of ​​the display panel.

3. The display device according to claim 1, wherein the display device further comprises: include: a data analyzer configured to analyze the input image data, determine whether the brightness of the current frame of the input image data is greater than the brightness of the previous frame of the input image data, and generate a selection signal indicating whether the brightness of the current frame of the input image data is greater than the brightness of the previous frame of the input image data; as well as A time constant selector is configured to determine a time constant of the power supply voltage in response to the selection signal.

4. The display device according to claim 3, wherein the display device further comprises: include: a driving controller configured to control the operation of the gate driver and the operation of the data driver, Wherein, the drive controller includes the data analyzer and the time constant selector.

5. The display device according to claim 3, in, The power supply voltage generator includes the data analyzer and the time constant selector.

6. The display device according to claim 3, in, The time constant selector comprises: a first switch configured to receive the selection signal from the data analyzer; a first time constant circuit connected to the first switch; a second switch configured to receive the selection signal from the data analyzer; a second time constant circuit connected to the second switch; a third switch configured to receive the selection signal from the data analyzer; and A third time constant circuit is connected to the third switch.

7. The display device according to claim 6, in, The first time constant circuit includes a first resistor connected to the first switch and a first capacitor connected in parallel with the first resistor. wherein the second time constant circuit includes a second resistor connected to the second switch and a second capacitor connected in parallel with the second resistor, and The third time constant circuit includes a third resistor connected to the third switch and a third capacitor connected in parallel to the third resistor.

8. The display device according to claim 7, in, When the brightness of the current frame of the input image data is equal to or less than the brightness of the previous frame of the input image data, the first switch is turned on, and the power supply voltage generator is connected to the first time constant circuit through the first switch, wherein, when the brightness of the current frame of the input image data is greater than the brightness of the previous frame of the input image data, and when the difference between the brightness of the current frame of the input image data and the brightness of the previous frame of the input image data is equal to or less than a threshold value, the second switch is turned on, and the power supply voltage generator is connected to the second time constant circuit through the second switch, wherein, when the brightness of the current frame of the input image data is greater than the brightness of the previous frame of the input image data, and when the difference between the brightness of the current frame of the input image data and the brightness of the previous frame of the input image data is greater than the threshold value, the third switch is turned on, and the power supply voltage generator is connected to the third time constant circuit through the third switch, and wherein the product of the resistance of the second resistor and the capacitance of the second capacitor is greater than the product of the resistance of the first resistor and the capacitance of the first capacitor, and the product of the resistance of the third resistor and the capacitance of the third capacitor is greater than the product of the resistance of the second resistor and the capacitance of the second capacitor.

9. The display device according to claim 1, in, The display panel includes an organic light emitting diode, and Wherein, the power supply voltage is output to the organic light emitting diode.

Images