Display device and method for driving the same

Abstract

The present invention relates to a display device and a method of driving the display device. The display device includes: a display panel including a plurality of pixels, pixels from among the plurality of pixels being coupled to scan lines and data lines; a scan driver configured to supply a first scan signal to the scan lines during a scan period in a frame and to supply a second scan signal to the scan lines during a compensation period after the scan period; and a data driver configured to supply a first data signal to the data lines in synchronization with the first scan signal and to supply a second data signal to the data lines in synchronization with the second scan signal, wherein the first data signal is generated based on input image data supplied from an image source, and the second data signal is generated based on converted image data obtained by converting the gray scale of the input image data.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority and benefit of Korean Patent Application No. 10 - 2019 - 0033888, filed with the Korean Intellectual Property Office on March 25, 2019, the entire contents of which are incorporated herein by reference. Technical field

[0003] Aspects of some example embodiments of the present disclosure generally relate to a display device and a driving method thereof. Background art

[0004] Generally, a display device includes a display panel and a panel driver. The display panel includes a plurality of gate lines and a plurality of data lines. The panel driver includes a gate driver configured to provide gate signals to the plurality of gate lines and a data driver configured to provide data voltages to the plurality of data lines.

[0005] The display panel displays an image based on the gate signals and data voltages. When the same image is displayed on the display panel for a long time, pixels in the display panel may deteriorate, and thus, image sticking may occur. In a specific area where a fixed image such as a logo, time, or caption is continuously displayed, the image sticking may be aggravated.

[0006] The above information disclosed in this background art section is only for enhancing the understanding of the background art, and thus, the above information may include information that does not constitute the prior art. Summary of the invention

[0007] Some example embodiments include a display device and a driving method thereof that can prevent or reduce the occurrence of image sticking due to a fixedly displayed image.

[0008] Some example embodiments may also include a display device and a driving method thereof that can prevent or reduce instances of image sticking by providing compensated image data to the display panel during a compensation period in a frame.

[0009] According to some example embodiments of the present disclosure, a display device includes: a display panel including a plurality of pixels, each of the plurality of pixels being coupled to a scan line and a data line; a scan driver configured to supply a first scan signal to the scan line during a scan period in a frame and supply a second scan signal to the scan line during a compensation period after the scan period; and a data driver configured to supply a first data signal to the data line in synchronization with the first scan signal and supply a second data signal to the data line in synchronization with the second scan signal, wherein the first data signal is generated based on input image data supplied from an image source, and the second data signal is generated based on converted image data obtained by converting the gray level of the input image data.

[0010] According to some example embodiments, the converted image data may be inverted image data generated based on inverted gray values obtained by inverting the gray levels of the input image data corresponding to the gray levels of the input image data. The sum of the gray level and the inverted gray value may correspond to the maximum gray value determined according to the number of bits of the input image data.

[0011] According to some example embodiments, the supply timing of the second scan signal in a frame may be the same or vary with respect to consecutive frames.

[0012] According to some example embodiments, the length of a frame may vary corresponding to the supply timing of the second scan signal.

[0013] According to some example embodiments, the supply timing of the second scan signal may be determined according to the number of times the first data signal corresponding to the same input image data is continuously supplied.

[0014] According to some example embodiments, the display device may further include a emission driver configured to supply an emission control signal to the pixels during an emission period between the scan period and the compensation period.

[0015] According to some example embodiments, the supply period of the emission control signal may vary corresponding to the supply timing of the second scan signal.

[0016] According to some example embodiments, the scan driver may supply the first scan signal to the scan line during a scan period in a frame in a first mode and supply the first scan signal and the second scan signal to the scan line in a second mode. The data driver may supply the first data signal to the data line in synchronization with the first scan signal in the first mode and supply the first data signal and the second data signal to the data line in the second mode.

[0017] According to some example embodiments, when a first data signal corresponding to the same input image data is continuously supplied a predetermined number of times or more, the scan driver and the data driver may operate in a second mode.

[0018] According to some example embodiments, the length of one frame in the first mode and the length of one frame in the second mode may be set to be equal to or different from each other.

[0019] According to some example embodiments, each pixel of a plurality of pixels may include: a light-emitting device; a first transistor coupled between a driving power supply voltage and the light-emitting device, the first transistor having a gate electrode coupled to a first node; a second transistor coupled between a data line and the first node, the second transistor having a gate electrode coupled to a scan line; and a capacitor coupled between the driving power supply voltage and the first node. When a second scan signal is supplied to the scan line, a voltage corresponding to the second data signal may be applied to the gate electrode of the first transistor via the second transistor and the first node.

[0020] According to some example embodiments of the present disclosure, in a method for driving a display device including a plurality of pixels, each of the plurality of pixels is coupled to a scan line and a data line, the method includes: generating a first data signal based on input image data supplied from an image source; supplying a first scan signal to the scan line during a scan period in a frame, and synchronously supplying the first data signal to the data line with the first scan signal; generating a second data signal based on converted image data obtained by converting the gray level of the input image data; and, according to an operation mode of the display device, supplying a second scan signal to the scan line during a compensation period after the scan period, and synchronously supplying the second data signal to the data line with the second scan signal.

[0021] According to some example embodiments, generating the second data signal may include: obtaining a gray level value of the input image data; generating an inverted gray level value by inverting the gray level of the input image data corresponding to the gray level value of the input image data; and generating the second data signal corresponding to the inverted gray level. The sum of the gray level value and the inverted gray level value may correspond to a maximum gray level value determined according to the number of bits of the input image data.

[0022] According to some example embodiments, the supply timing of the second scan signal in a frame may be the same or vary with respect to consecutive frames.

[0023] According to some example embodiments, the length of one frame may vary corresponding to the supply timing of the second scan signal.

[0024] According to some example embodiments, the method may further include: determining the supply timing of the second scan signal based on the number of times the first data signal corresponding to the same input image data is continuously supplied.

[0025] According to some example embodiments, the method may further include: after supplying a first scan signal and a first data signal, supplying a transmit control signal to a pixel. A supply period of the transmit control signal may vary corresponding to a supply timing of a second scan signal.

[0026] According to some example embodiments, the method may further include: determining an operation mode of the display device as any one of a first mode and a second mode. When the operation mode is the second mode, supplying of a second scan signal and a second data signal may be performed.

[0027] According to some example embodiments, a length of one frame in the first mode and a length of one frame in the second mode may be set to be equal to or different from each other.

[0028] According to some example embodiments, determining the operation mode of the display device may include: when a first data signal corresponding to the same input image data is continuously supplied a predetermined number of times or more, determining the operation mode as the second mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Aspects of some example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, the example embodiments may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the example embodiments to those skilled in the art.

[0030] In the drawings, for clarity of illustration, sizes may be exaggerated. It will be understood that when an element is referred to as being “between” two elements, the element may be the only element between the two elements, or there may also be one or more intervening elements. Like reference numerals refer to like elements throughout.

[0031] Figure 1 is a block diagram illustrating a display device according to some example embodiments of the present disclosure.

[0032] Figure 2 is a diagram illustrating Figure 1 further details of some example embodiments of the pixel shown in

[0033] Figure 3 is a timing diagram illustrating examples of signals supplied to the pixel shown in Figure 2 in a first mode of a display device according to some example embodiments of the present disclosure.

[0034] Figure 4 is a diagram illustrating signals supplied to the pixel shown inFigure 2 A timing diagram of an example of the signal of the pixel shown in

[0035] Figure 5 This is a timing diagram of another example of the signal supplied to the pixel shown in the second mode of the display device according to some example embodiments of the present disclosure. Figure 2 A timing diagram of another example of the signal of the pixel shown in

[0036] Figure 6 This is a diagram illustrating the change in transistor characteristics when a fixed image is displayed for a long time according to some example embodiments of the present disclosure.

[0037] Figure 7 This is a diagram illustrating the occurrence of afterimages when a fixed image is displayed for a long time according to some example embodiments of the present disclosure.

[0038] Figure 8 This is a timing diagram of another example of the signal supplied to the pixel shown in Figure 2 A timing diagram of another example of the signal of the pixel shown in

[0039] Figure 9 This is a timing diagram of another example of the signal supplied to the pixel shown in the second mode of the display device according to some example embodiments of the present disclosure. Figure 2 A timing diagram of another example of the signal of the pixel shown in Detailed Description

[0040] Hereinafter, aspects of some example embodiments will be described in more detail with reference to the accompanying drawings. However, the present invention may be embodied in various different forms and should not be construed as limited to the example embodiments illustrated herein. Instead, these embodiments are provided as examples so that the present disclosure will be thorough and complete, and will convey the aspects and features of the present invention more fully to those skilled in the art. Therefore, processes, elements, and techniques that are not necessary for a person of ordinary skill in the art to fully understand the aspects and features of the present invention may not be described or shown in the drawings. Unless otherwise noted, the same reference numerals refer to the same elements throughout the drawings and the written description, and thus, the description of the same reference numerals may not be repeated. In the drawings, for clarity, the relative dimensions of elements, layers, and regions may be exaggerated.

[0041] It will be understood that although the terms "first", "second", "third", etc. may be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, first component, first region, first layer or first section described hereinafter may be referred to as a second element, second component, second region, second layer or second section without departing from the spirit and scope of the present invention.

[0042] Spatially relative terms, such as "beneath", "below", "lower", "under", "above", "upper", etc., may be used herein for purposes of explanation to describe the relationship of one element or feature shown in the figures to another element or feature. It will be understood that the spatially relative terms are intended to cover different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, an element described as "beneath" or "below" or "under" another element or feature will then be oriented "above" the other element or feature. Thus, the exemplary terms "beneath" and "below" can cover both an orientation of above and below. The device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein should be interpreted accordingly.

[0043] It will be understood that when an element or layer is referred to as being "on", "connected to" or "coupled to" another element or layer, it can be directly on, directly connected to or coupled to the other element or layer, or there may be one or more intervening elements or layers. Further, it will be understood that when an element or layer is referred to as being "between" two elements or layers, it can be the only element or layer between the two elements or layers, or there may be one or more intervening elements or layers.

[0044] The terms used herein are for the purpose of describing particular embodiments and are not intended to limit the present invention. As used herein, the singular forms "a" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that when the terms "comprises" and / or "comprising" are used in this specification, they specify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. When an expression such as "at least one of..." follows a list of elements, it modifies the entire list of elements and not the individual elements of the list.

[0045] As used herein, the terms "substantially", "about" and similar terms are used as approximate terms and not as terms of degree, and are intended to account for the inherent deviations in measured or calculated values that would be recognized by a person of ordinary skill in the art. In addition, when describing embodiments of the present invention, the use of "may" refers to "one or more embodiments of the present invention". Additionally, when describing embodiments of the present invention, the use of alternative language such as "or" refers to "one or more embodiments of the present invention" for each of the listed corresponding items. As used herein, the term "use" may be considered synonymous with the term "utilize". Moreover, the term "exemplary" is intended to refer to an example or illustration.

[0046] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by a person of ordinary skill in the technical field to which the present invention pertains. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and / or this specification, and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0047] Figure 1 is a block diagram illustrating a display device according to some example embodiments of the present disclosure.

[0048] Reference Figure 1 , a display device according to some example embodiments of the present disclosure may include a display panel 100 including a plurality of pixels PX, a scan driver 210, a data driver 220, an emission driver 230, a power supply 240, a controller 250, and an image corrector 260.

[0049] The image corrector 260 may receive input image data DATA from an external source (e.g., an image source or an external source). According to some example embodiments, the image corrector 260 may supply the input image data DATA to the controller 250, or may correct the input image data DATA and supply the corrected image data RDATA to the controller 250. According to some example embodiments, the image corrector 260 may generate the corrected image data RDATA by increasing the brightness of the input image data DATA by an offset (e.g., a predetermined offset). According to some example embodiments, the image corrector 260 may pre-store the brightness offset for correcting the image data RDATA in the form of a look-up table.

[0050] According to some example embodiments of the present disclosure, the image corrector 260 may generate compensation image data IDATA from the input image data DATA and supply the compensation image data IDATA to the controller 250.

[0051] The compensated image data IDATA may be data having a gray scale that is the gray scale inversion of the input image data DATA. For example, the image corrector 260 may generate the compensated image data IDATA by obtaining the luminance information of the input image data DATA and inverting the luminance value. That is, the image corrector 260 may obtain the gray scale value included in the input image data DATA (for example, the gray scale value that may be represented by 8 to 12 bits). In addition, the image corrector 260 may calculate the inverted gray scale value corresponding to the gray scale value, which is obtained by inverting the gray scale of the input image data DATA. That is to say, the image corrector 260 may symmetrically adjust the gray scale value of the input image data DATA within the range of all gray scale values. Therefore, the sum of the gray scale value of the input image data DATA and the inverted gray scale value may represent the maximum gray scale value (for example, 255) of the input image data DATA.

[0052] According to some example embodiments, when the input data (gamma data) of the input image data DATA is represented by 8 bits, all gray scales are 256 gray scales, and the range of all gray scale values becomes 0 to 255. When inverting the gray scale value of the input image data DATA within the range of all gray scale values, the sum of the gray scale value of the input image data DATA and the gray scale value of the compensated image data IDATA having a gray scale that is the gray scale inversion of the input image data DATA may be 255 as the maximum gray scale value.

[0053] According to some example embodiments, when the gray scale value of the input image data DATA is 0 (for example, when the input image is a black image), the gray scale value of the compensated image data IDATA may be 255 (for example, a white image). On the other hand, when the gray scale value of the input image data DATA is 255, the gray scale value of the compensated image data IDATA may be 0.

[0054] However, according to some example embodiments of the present disclosure, the method for generating the compensated image data IDATA is not limited to the embodiments described above. That is to say, according to some example embodiments, the sum of the gray scale value of the input image data DATA and the gray scale value of the compensated image data IDATA having a gray scale that is the gray scale inversion of the input image data DATA may be set to a gray scale value less than or greater than the maximum gray scale.

[0055] The compensated image data IDATA is generated so as to prevent the threshold voltage characteristics of the pixel PX from being changed when the input image data of the fixed image is displayed on the display panel 100 for a long time. That is to say, when the long-term display of the fixed image changes the threshold voltage characteristics of a specific pixel PX, the compensated image data IDATA may be generated to correspond to the data voltage required to reset the threshold voltage characteristics to the original value. The following will refer to Figure 7A correction of the threshold voltage characteristics of pixels PX by using compensation image data IDATA will be described in more detail.

[0056] According to some exemplary embodiments of the present disclosure, the compensation image data IDATA may be generated by the image corrector 260 for each frame. Alternatively, the compensation image data IDATA may be pre-stored in the form of a look-up table or the like corresponding to the input image data DATA. However, embodiments according to the present disclosure are not limited thereto.

[0057] The controller 250 may receive the input image data DATA from the image corrector 260, or may receive the corrected image data RDATA or the compensation image data IDATA from the image corrector 260. Moreover, the controller 250 may receive a control signal from the outside. The control signal may include a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, etc., but the present disclosure is not limited thereto.

[0058] The controller 250 may generate a scan drive control signal CONT1, a data drive control signal CONT2, a transmit drive control signal CONT3, and a power drive control signal CONT4 based on the control signal. The scan drive control signal CONT1 generated by the controller 250 may be supplied to the scan driver 210, the data drive control signal CONT2 generated by the controller 250 may be supplied to the data driver 220, the transmit drive control signal CONT3 generated by the controller 250 may be supplied to the transmit driver 230, and the power drive control signal CONT4 generated by the controller 250 may be supplied to the power supply 240.

[0059] The scan drive control signal CONT1 may include a plurality of clock signals and a scan start signal. The scan start signal is a signal for generating a scan signal for displaying one frame of an image. The clock signal is a synchronization signal for sequentially applying the scan signal to the scan lines S1 to Sn.

[0060] The data drive control signal CONT2 may include a source start pulse and a clock signal. The source start pulse may control the sampling start time of the data, and the clock signal may be used to control the sampling operation.

[0061] The transmit drive control signal CONT3 may include a transmit start pulse and a clock signal. The transmit start pulse may control the first timing of the transmit control signal. The clock signal may be used to shift the transmit start pulse.

[0062] In addition, the controller 250 may generate an image data signal DAT by processing the input image data DATA, the corrected image data RDATA, or the compensation image data IDATA, and supply the generated image data signal DAT to the data driver 220.

[0063] According to some example embodiments of the present disclosure, the controller 250 may control the scan driver 210, the data driver 220, and the emission driver 230 according to the operation mode. For example, in the first mode, the controller 250 may control the scan driver 210, the data driver 220, and the emission driver 230 to supply a scan signal and a data signal to the pixels during a scan period in a frame, and supply an emission control signal to the pixel PX during an emission period after the scan period. For example, in the second mode, the controller 250 may control the scan driver 210, the data driver 220, and the emission driver 230 to further supply a scan signal and a data signal to the pixel PX during a compensation period after the emission period. In an embodiment, the data signal supplied to the pixel PX during the compensation period may be different from the data signal supplied to the pixel PX during the scan period. For example, the data signal supplied to the pixel PX during the scan period may be generated based on the input image data DATA or the corrected image data RDATA, and the data signal supplied to the pixel PX during the compensation period may be generated based on the compensation image data IDATA.

[0064] The scan driver 210 may supply a scan signal to the scan lines S1 to Sn corresponding to the scan driving control signal CONT1. The scan signal may be set to a gate-on voltage (e.g., a high-level voltage) at which the transistors included in the pixel PX may be turned on. According to some example embodiments of the present disclosure, the scan driver 210 may supply a scan signal having a conductive level to the scan lines S1 to Sn at least twice during a frame.

[0065] When the display device operates in the second mode, the scan driver 210 may supply a scan signal having a conductive level to the scan lines S1 to Sn at least twice in a frame. Accordingly, the supply timing of the scan signal may vary.

[0066] The data driver 220 may supply a data signal corresponding to the image data signal DAT to the data lines D1 to Dm corresponding to the data driving control signal CONT2. The data signal supplied to the data lines D1 to Dm may be supplied to the pixel PX to which the scan signal is supplied. To this end, the data driver 220 may supply the data signal to the data lines D1 to Dm in synchronization with the scan signal.

[0067] According to some example embodiments of the present disclosure, when the display device operates in the second mode, the data driver 220 may supply data signals corresponding to the input image data DATA or the corrected image data RDATA to the data lines D1 to Dm in synchronization with a scan signal having an active level during a scan period (hereinafter referred to as a first scan signal). In addition, the data driver 220 may supply data signals corresponding to the compensation image data IDATA to the data lines D1 to Dm in synchronization with a scan signal having an active level during a compensation period (hereinafter referred to as a second scan signal).

[0068] The emission driver 230 may supply emission control signals to the emission control lines E1 to En corresponding to the emission drive control signal CONT3. The emission control signals may be used to control the emission time of the pixels PX. For example, during a supply period of the emission control signal (e.g., during a supply period of the emission control signal having an active level), a specific pixel PX supplied with the emission control signal may be set to an emission state, and during other time periods (e.g., during a supply period of the emission control signal having a cut-off level), the specific pixel PX may be set to a non-emission state. According to some example embodiments of the present disclosure, the emission driver 230 may supply emission control signals having an active level to the emission control lines E1 to En during an emission period between the scan period and the compensation period.

[0069] The power supply 240 may supply a driving power supply voltage to each pixel PX in the display panel 100 based on the power drive control signal CONT4. For example, the power supply 240 may supply a first driving power supply voltage ELVDD and a second driving power supply voltage ELVSS to the display panel 100. The first driving power supply voltage ELVDD may be set to a high potential voltage, and the second driving power supply voltage ELVSS may be set to a low potential voltage.

[0070] The display panel 100 may include a plurality of pixels PX coupled to the data lines D1 to Dm, the scan lines S1 to Sn, and the emission control lines E1 to En. When a scan signal is supplied from one of the scan lines S1 to Sn coupled to each pixel PX, the pixel PX may be supplied with a data signal from one of the data lines D1 to Dm coupled to the pixel PX. The pixel PX supplied with the data signal may control the amount of current flowing from the first driving power supply voltage ELVDD through a light emitting device (e.g., an organic light emitting diode) to the second driving power supply voltage ELVSS corresponding to the data signal. The light emitting device may generate light having a brightness (e.g., a predetermined brightness) corresponding to the amount of current.

[0071] Meanwhile, although Figure 1The figure illustrates a case where the image corrector 260 is an independent component, but the present disclosure is not limited thereto. That is, according to some example embodiments, the image corrector 260 may be integrally formed with or installed in the controller 250. Alternatively, the function of the image corrector 260 may be separately performed by at least one of the controller 250, the scan driver 210, and the data driver 220.

[0072] Figure 2 is a diagram Figure 1 illustrating an embodiment of the pixel shown in the figure. For ease of description, Figure 2 the figure illustrates a pixel PX coupled to the i-th scan line Si, the j-th data line Dj, and the i-th emission control line Ei.

[0073] Referring Figure 2 , according to some example embodiments of the present disclosure, the pixel PX may include first to third transistors T1, T2, and T3, a storage capacitor Cst, and a light emitting device OLED.

[0074] The first transistor (driving transistor) T1 is coupled between the first driving power supply voltage ELVDD and the third transistor T3. The gate electrode of the first transistor T1 is coupled to the first node N1. The first transistor T1 may be turned on corresponding to the voltage of the first node N1. When the first transistor T1 is turned on, a driving current corresponding to the voltage stored in the storage capacitor Cst may flow from the first driving power supply voltage ELVDD through the third transistor T3 to the light emitting device OLED.

[0075] The second transistor (switching transistor) T2 is coupled between the data line Dj and the first node N1. The gate electrode of the second transistor T2 is coupled to the scan line Si. When a scan signal having an active level is supplied to the scan line Si, the second transistor T2 may be turned on to supply the data signal supplied to the data line Dj to the first node N1.

[0076] The third transistor (emission control transistor) T3 is coupled between the first transistor T1 and the light emitting device OLED. The gate electrode of the third transistor T3 is coupled to the emission control line Ei. When an emission control signal having an active level is supplied to the emission control line Ei, the third transistor T3 may be turned on to selectively supply the driving current supplied from the first transistor T1 to the light emitting device OLED.

[0077] The storage capacitor Cst is coupled between the first node N1 and the first driving power supply voltage ELVDD. When the data signal is supplied to the first node N1 via the second transistor T2, the storage capacitor Cst may store a voltage corresponding to the data signal.

[0078] The first electrode of the light-emitting device OLED is coupled to the third transistor T3, and the second electrode of the light-emitting device OLED is coupled to the second driving power supply voltage ELVSS. The first electrode may be an anode electrode, and the second electrode may be a cathode electrode. In response to the amount of the driving current, the light-emitting device OLED may generate light having a brightness (e.g., a predetermined brightness) corresponding to the amount of the driving current flowing from the first driving power supply voltage ELVDD via the first transistor T1 and the third transistor T3 to the second driving power supply voltage ELVSS.

[0079] In Figure 2 the embodiment shown, the transistors T1 to T3 constituting the pixel PX may be implemented as PMOS transistors. However, in various embodiments, at least some of the transistors T1 to T3 may be implemented as NMOS transistors, and accordingly, various modifications may be made to the pixel circuit.

[0080] Although Figure 2 an example of the pixel structure is illustrated, the pixel PX of the display device according to an embodiment of the present disclosure is not limited to Figure 2 the pixel structure shown, and may have various structures.

[0081] Hereinafter, signals supplied to the Figure 2 pixel shown will be described in more detail according to various embodiments of the present disclosure.

[0082] Figure 3 is a timing diagram illustrating an example of signals supplied to the Figure 2 pixel shown in the first mode of the display device. In Figure 3 it, the vertical synchronization signal Vsync is illustrated to represent one frame.

[0083] One frame in the first mode may be configured with a scan period SP and an emission period EP. The length of one frame in the first mode may be set corresponding to the driving frequency of the display device. For example, the length of one frame may be set corresponding to a driving frequency of 60 Hz, but the present disclosure is not limited thereto.

[0084] Referring together to Figure 2 and Figure 3 , during the scan period SP, the data signal DS is supplied to the data line Dj, and the scan signal SS having a conductive level is supplied to the scan line Si. Then, the first node N1 may be charged with a voltage corresponding to the data signal DS. The data signal DS may be generated based on input image data DATA provided from the outside or the image corrector 260.

[0085] During the scanning period SP, the emission control signal has a cut-off level, and thus the third transistor T3 is cut off. Therefore, during the scanning period SP, the current path from the first driving power supply voltage ELVDD to the second driving power supply voltage ELVSS is blocked, and thus, the light-emitting device OLED does not emit light.

[0086] During the emission period EP, an emission control signal having a conductive level is supplied, and thus, the third transistor T3 is turned on. Then, a current path is formed from the first driving power supply voltage ELVDD through the light-emitting device OLED to the second driving power supply voltage ELVSS, and thus, the light-emitting device OLED emits light. The amount of current flowing through the light-emitting device OLED can correspond to the voltage charged in the first node N1 during the scanning period SP.

[0087] According to some example embodiments, a period for initializing the gate voltage of the first transistor T1 or compensating for the threshold voltage of the first transistor T1 may be further provided after the emission period EP. According to some example embodiments, a period for sensing the characteristics of each pixel PX in the pixel PX may be further provided after the emission period EP.

[0088] At the same time, in Figure 3 a case where the start time (e.g., falling edge) of the scan signal SS is not synchronized with the start time of the vertical synchronization signal Vsync is illustrated. However, embodiments according to the present disclosure are not limited thereto. For example, when the scan line Si is the first scan line S1, the start time of the scan signal SS may be synchronized with the start time of the vertical synchronization signal Vsync.

[0089] Figure 4 is a timing diagram illustrating an example of signals supplied to the pixels shown in Figure 2 in the second mode of the display device. Figure 5 is a timing diagram illustrating another example of signals supplied to the pixels shown in Figure 2 in the second mode of the display device. Figure 6 is a diagram illustrating a change in transistor characteristics when a fixed image is displayed for a long time. Figure 7 is a diagram illustrating the occurrence of afterimages when a fixed image is displayed for a long time.

[0090] Compared with the first mode, one frame in the second mode may further include a compensation period CP after the emission period EP. The length of one frame in the second mode may be equal to or longer than the length of one frame in the first mode. For example, as Figure 4As shown, the length of a frame in the second mode can be set corresponding to a driving frequency of 60 Hz, and the length of a frame in the second mode is equal to the length of a frame in the first mode. Accordingly, corresponding to the length of the compensation period CP, the length of the emission period EP can be shorter than the length of the emission period EP in the first mode. According to some example embodiments, when the length of a frame in the first mode is set corresponding to a driving frequency of 60 Hz, the length of a frame in the second mode can be set corresponding to a driving frequency of 40 Hz, but embodiments according to the present disclosure are not limited thereto.

[0091] Alternatively, as Figure 5 shown, the length of a frame in the second mode can be set to be different from the length of a frame in the first mode. For example, the length of a frame in the second mode can be longer than the length of a frame in the first mode by the length of the compensation period CP. When the length of a frame is set to be longer than the length of a frame in a general driving method for the purpose of the compensation period CP, the pixel PX can emit light during a sufficient emission period EP, and thus a degradation in the quality of the displayed image can be prevented.

[0092] According to some example embodiments of the present disclosure, the length of the compensation period CP can vary. When the length of the compensation period CP varies, the length of the emission period EP in the embodiment shown in Figure 4 can vary, or the length of a frame in the embodiment shown in Figure 5 can vary. Embodiments in which the length of the compensation period CP varies will be described in more detail below with reference to Figure 9 .

[0093] The control of the length of a frame described above can be performed by a vertical synchronization signal Vsync supplied from the outside. For example, in the embodiment shown in Figure 1 , the controller 250 can control the length of a frame in response to a vertical synchronization signal Vsync supplied from the outside. That is, the controller 250 can determine the start time of a frame in response to a vertical synchronization signal Vsync supplied from the outside.

[0094] Alternatively, the control of the length of a frame can be performed by a separate control signal received from the outside. For example, the controller 250 can determine the start time of a frame and the length according to the start time based on information or reception timing in a control signal corresponding to the second mode received from the outside.

[0095] In addition to Figure 4 and Figure 5 where the lengths of frames in the embodiments shown are set to be different from each other, Figure 4 and Figure 5The embodiments shown are substantially identical to each other, and thus, the following description can be equivalently applied to Figure 4 and Figure 5 .

[0096] Referring together to Figure 2 , Figure 4 and Figure 5 , during a scanning period SP, a first data signal DS1 is supplied to a data line Dj, and a first scanning signal SS1 having a conductive level is supplied to a scanning line Si. Then, a first node N1 can be charged to a voltage corresponding to the first data signal DS1. The first data signal DS1 can be generated based on input image data DATA or corrected image data RDATA provided from an external source or an image corrector 260.

[0097] The corrected image data RDATA can be corrected and generated such that, as described above, the luminance of the input image data DATA is increased by an offset (e.g., a predetermined offset). When a data signal is provided based on the corrected image data RDATA, even if the length of an emission period EP is reduced due to a compensation period CP during a frame, the pixel PX emits light with higher luminance during the emission period EP of a frame. Therefore, the difference in the quality of an image viewed by a user can be minimized or reduced.

[0098] During the scanning period SP, the emission control signal has a cut-off level, and thus, a third transistor T3 is cut off. Therefore, during the scanning period SP, a current path from a first driving power supply voltage ELVDD to a second driving power supply voltage ELVSS is blocked, and thus, the light-emitting device OLED does not emit light.

[0099] During the emission period EP, an emission control signal having a conductive level is supplied, and thus, the third transistor T3 is turned on. Then, a current path from the first driving power supply voltage ELVDD through the light-emitting device OLED to the second driving power supply voltage ELVSS is formed, and thus, the light-emitting device OLED emits light. The amount of current flowing through the light-emitting device OLED can correspond to the voltage charged in the first node N1 during the scanning period SP.

[0100] During the compensation period CP, a second data signal DS2 is supplied to the data line Dj, and a second scanning signal SS2 having a conductive level is supplied to the scanning line Si. Then, the first node N1 can be charged to a voltage corresponding to the second data signal DS2.

[0101] The second data signal DS2 can be generated based on compensation image data IDATA provided from the image corrector 260. As described above, the compensation image data IDATA can be data having a gray scale that is the gray-scale inversion of the input image data DATA.

[0102] According to some example embodiments, when a first data signal DS1 regarding the same image is supplied to a pixel PX for a long time, characteristics of a transistor (e.g., a first transistor T1) provided in the pixel PX may deteriorate. That is, when the gate electrode of the transistor is supplied with the same voltage for a long time, as shown in Figure 6 , characteristics of the transistor may change (601). When the characteristics of the transistor change, the pixel PX does not correctly emit light having a desired luminance, and as shown in Figure 7 , an afterimage may occur.

[0103] According to some example embodiments of the present disclosure, during a compensation period CP, a second data signal DS2 corresponding to compensation image data IDATA may be supplied to the pixel PX such that the characteristics of the transistor may be restored (602). For example, according to some example embodiments of the present disclosure, during the compensation period CP, a voltage of the second data signal DS2 corresponding to the compensation image data IDATA is applied to a first node N1 (i.e., the gate electrode of the first transistor T1) such that the characteristics of the first transistor T1 may be corrected.

[0104] Meanwhile, although the second data signal DS2 is applied to the pixel PX during the compensation period CP, no emission control signal is supplied, and thus a third transistor T3 is turned off. Accordingly, a current path from a first driving power supply voltage ELVDD to a second driving power supply voltage ELVSS is blocked, and thus, the light emitting device OLED does not emit light.

[0105] As described above, according to some example embodiments of the present disclosure, during the compensation period CP, the second data signal DS2 corresponding to the compensation image data IDATA may be supplied to the pixel PX such that the first transistor T1 in a specific pixel PX may be prevented from deteriorating due to a fixed image. Thus, instances in which an afterimage occurs on the display panel 100 may be prevented or reduced.

[0106] Figure 8 is a timing diagram illustrating an example of signals supplied to the pixel shown in Figure 2 .

[0107] In the embodiment shown in Figure 8 , the display device may operate in a first mode from a first frame to an nth frame and may operate in a second mode starting from the (n + 1)th frame. Accordingly, the display device may operate in the same manner as described with reference to from the first frame to the nth frame, and may operate in the same manner as described with reference to Figure 3 and starting from the (n + 1)th frame and Figure 4 and Figure 5 .

[0108] According to some example embodiments, when the display device is driven, the display device may operate in a first mode for an initial n frames and then operate in a second mode. According to some example embodiments, while the display device is operating in the first mode, when a fixed image is repeatedly supplied to the display panel for n frames, the mode of the display device may be switched to the second mode so that the display device operates in the second mode starting from the (n + 1)-th frame.

[0109] Here, n is a fixed value preset during the manufacture of the display device and may be stored in the controller 250 or may be variably set by a control signal supplied from the outside.

[0110] Except that the mode of the display device is switched so that the display device operates in the switched mode, Figure 8 the embodiment of the supplied signal shown in Figures 3 to 5 is basically the same as the embodiment described with reference to

[0111] Figure 9 is a timing diagram illustrating another example of a signal supplied to the pixel shown in Figure 2 in the second mode of the display device.

[0112] With reference to Figure 9 in various embodiments of the present disclosure, the length of the compensation period CP may vary. Accordingly, the length of the compensation period CP may be defined by the supply timing of the second scan signal SS2.

[0113] For example, the length of the compensation period CP may be determined corresponding to the number of times (e.g., time or number of frames) that the same data signal (e.g., a data signal of a fixed image) is continuously supplied to the corresponding pixel PX. According to some example embodiments, when the time during which the same data signal is continuously supplied to the corresponding pixel PX becomes longer, the length of the compensation period CP may become longer corresponding to the time (e.g., the supply timing of the second scan signal SS2 in one frame may become faster).

[0114] When the compensation period CP changes, when the length of one frame as shown in Figure 9 is fixed, the length of the emission period EP may be shortened or lengthened according to the length of the compensation period CP. That is, when the length of the compensation period CP in one frame is extended, the emission period EP may be shortened corresponding to the length of the compensation period CP.

[0115] According to some example embodiments, as shown in Figure 5As shown in the figure, when the compensation period CP changes, the length of the emission period EP may not change. Conversely, the length of a frame may change correspondingly with the length of the compensation period CP. That is, the length of a frame may be determined as a value obtained by adding the length of the determined compensation period CP to the lengths of the scanning period SP and the emission period EP.

[0116] In addition to the change in the length of the compensation period CP between frames, Figure 9 the embodiments of the supplied signals shown in the figure are substantially the same as those described in the references Figure 4 and Figure 5 and thus, a detailed description thereof will be omitted.

[0117] In a display device and a driving method of the display device according to some exemplary embodiments of the present disclosure, there may be instances where the occurrence of afterimages due to a fixed image displayed for a long time in a specific region is prevented or reduced.

[0118] Those of ordinary skill in the art of the present invention understand that the present invention may be implemented in other specific forms without changing the technical concept or departing from the spirit and scope of the embodiments according to the present disclosure. The exemplary embodiments should be considered as merely descriptive and not for the purpose of limitation. Therefore, the scope of the present invention is not defined by the detailed description of the present invention, but by the appended claims and their equivalents, and all differences within the scope of the present invention will be construed as being included in the present invention.

Claims

1. A display device, comprising: A display panel including a plurality of pixels, wherein pixels from the plurality of pixels are coupled to scan lines and data lines; A scan driver configured to supply a first scan signal to the scan lines during a scan period in a frame and to supply a second scan signal to the scan lines during a compensation period after the scan period; And A data driver configured to supply a first data signal to the data lines synchronously with the first scan signal and to supply a second data signal to the data lines synchronously with the second scan signal, wherein the first data signal is generated based on input image data supplied from an image source, the second data signal is generated based on converted image data obtained by converting the gray level of the input image data, and the converted image data is inverted image data generated based on inverted gray levels, the inverted gray levels being obtained by inverting the gray levels of the input image data corresponding to the gray levels of the input image data, and the sum of the gray level and the inverted gray level corresponding to a maximum gray level determined according to the number of bits of the input image data.

2. The display device according to claim 1, wherein, The supply timing of the second scan signal in the frame is the same or varies with respect to consecutive frames.

3. The display device according to claim 2, wherein, The length of the frame varies corresponding to the supply timing of the second scan signal.

4. The display device according to claim 2, wherein The supply timing of the second scan signal is determined according to the number of times the first data signal corresponding to the same input image data is continuously supplied.

5. The display device according to claim 2, further comprising: An emission driver configured to supply an emission control signal to the pixels during an emission period between the scan period and the compensation period.

6. The display device according to claim 1, wherein, The scan driver is configured to supply the first scan signal to the scan lines during the scan period in the frame in a first mode and to supply the first scan signal and the second scan signal to the scan lines in a second mode, wherein the data driver is configured to supply the first data signal to the data lines synchronously with the first scan signal in the first mode and to supply the first data signal and the second data signal to the data lines in the second mode.

7. The display device according to claim 6, wherein, The scan driver and the data driver are configured to operate in the second mode in response to the first data signal corresponding to the same input image data being continuously supplied a predetermined number of times or more.

8. The display device according to claim 1, wherein, Each pixel of the plurality of pixels includes: A light-emitting device; A first transistor coupled between a driving power supply voltage and the light-emitting device, the first transistor having a gate electrode coupled to a first node; A second transistor coupled between the data line and the first node, the second transistor having a gate electrode coupled to the scan line; and A capacitor coupled between the driving power supply voltage and the first node, Among them, in response to the second scan signal being supplied to the scan line, a voltage corresponding to the second data signal is applied to the gate electrode of the first transistor via the second transistor and the first node.

9. A method for driving a display device, the display device including a plurality of pixels, pixels from among the plurality of pixels being coupled to scan lines and data lines, the method including: generating a first data signal based on input image data supplied from an image source; during a scan period in a frame, supplying a first scan signal to the scan lines and synchronously supplying the first data signal to the data lines; generating a second data signal based on converted image data obtained by converting grayscale values of the input image data; and according to an operation mode of the display device, during a compensation period after the scan period, supplying a second scan signal to the scan lines and synchronously supplying the second data signal to the data lines, wherein the converted image data is inverted image data generated based on inverted grayscale values obtained by inverting the grayscale values of the input image data corresponding to the grayscale values of the input image data, and the sum of the grayscale values and the inverted grayscale values corresponds to a maximum grayscale value determined according to the number of bits of the input image data.

Images