Display device and method of operating a display device

Abstract

A display device and a method for operating the display device are disclosed, which can change the refresh cycle in a low-speed operating mode to improve response characteristics. The display device includes: a display panel; and a panel driving circuit configured to drive the display panel, wherein in the low-speed operating mode, the display device is configured to control the panel driving circuit: perform multiple refreshes during the initial time period of a first frame; and change the refresh cycle after the multiple refreshes and perform refreshes based on the changed refresh cycle.

Description

Technical Field

[0001] The present invention relates to a display device, and more specifically, to a display device capable of changing the refresh cycle to improve response characteristics during low-speed operation, and a method for operating the display device. Background Technology

[0002] With the development of the information society, the demand for display devices for displaying images is increasing in various forms. Therefore, various display devices such as liquid crystal displays (LCDs) and organic light-emitting diode (OLED) displays are being used. Among these display devices, OLED displays have attracted attention due to their fast response speed, excellent luminous efficiency, wide viewing angle, and superior color reproduction rate.

[0003] In an organic light-emitting display device, pixels, each including an organic light-emitting diode (OLED), are arranged in a matrix, and the brightness of the pixels is adjusted based on the grayscale level of image data. Each pixel includes a driving TFT (thin-film transistor) that controls the driving current flowing through the OLED based on the gate-source voltage, and at least one switching TFT for programming the gate-source voltage of the driving TFT. The display device adjusts the display grayscale level (brightness) based on the amount of light emitted from the OLED in proportion to the driving current. Summary of the Invention

[0004] Organic light-emitting display devices drive pixels at a low speed when the input image changes little, in order to reduce power consumption.

[0005] However, organic light-emitting display devices have the problem of a large refresh cycle for image data when operating at low speeds, which means that the image data filled into the pixels does not remain at the target level and there is a leakage problem.

[0006] In addition, organic light-emitting display devices suffer from response delays due to the hysteresis characteristics of the driving TFTs during low-speed operation.

[0007] Therefore, the inventors of this invention have invented a display device and a method for operating the display device that can improve image quality and response characteristics during low-speed operation.

[0008] One aspect of the present invention is to provide a display device capable of changing the refresh cycle to improve response characteristics during low-speed operation, and a method for operating the display device.

[0009] Furthermore, another aspect of the present invention is to provide a display device capable of maintaining a target level of image data charged to pixels during low-speed operation to improve image quality, and a method for operating the display device.

[0010] Additional features and aspects of the invention will be set forth in part in the description below, some of which will be obvious from the description or may be learned by practice of the inventive concept provided herein. Other features and aspects of the inventive concept may be realized and obtained by means of structures specifically pointed out in the description or derivatives thereof, the claims, and the drawings.

[0011] A display device according to an embodiment of the present invention may include: a display panel; and a panel driving circuit configured to drive the display panel, wherein in a low-speed operation mode, the display device is configured to control the panel driving circuit to: perform multiple refreshes during the initial time period of a first frame, and after the multiple refreshes, change the refresh period and perform refreshes based on the changed refresh period.

[0012] Preferably, the display device is configured to change the refresh period for each frame after performing the multiple refreshes.

[0013] Preferably, the display device is configured to change the refresh rate for each frame during a predetermined number of frames.

[0014] Preferably, the display device is configured to: perform a refresh at a first time interval after performing the multiple refreshes in the first frame; and perform a refresh at a second time interval greater than the first time interval in the second frame.

[0015] Preferably, the display device is further configured to perform a refresh in the third frame at an interval greater than the second time period.

[0016] Preferably, the display device is configured to increase the refresh period as frames progress after performing the multiple refreshes.

[0017] Preferably, the display device is configured to: continuously perform multiple refreshes at a first frequency and a predetermined number of times during the initial period of the first frame; perform refreshes at intervals of a first time period during the remaining period of the first frame; and perform refreshes at intervals of a second time period longer than the first time period in the second frame.

[0018] Preferably, in the low-speed operation mode of the display panel, the operating frequency of the display device gradually decreases.

[0019] Preferably, the display device is configured to: continuously perform multiple refreshes at a first frequency and a predetermined number of times during the initial period of the first frame; perform n refreshes at intervals of a first time period during the remaining periods of the first frame; and perform m refreshes at intervals of a second time period during the second frame, where n and m are positive integers greater than or equal to 2.

[0020] Preferably, the multiple refreshes are performed at a frequency of 30Hz during the initial period of the first frame, the first period being set to correspond to a period of 10Hz and the second period being set to correspond to a period of 5Hz.

[0021] Preferably, the third time period is set to a period corresponding to a frequency of 2H or lower.

[0022] A display device according to an embodiment of the present invention may include: a display panel; a source driver configured to drive data lines of the display panel; a gate driver configured to drive gate lines of the display panel; and a timing controller configured to control the source driver and the gate driver in a low-speed operation mode: performing multiple refreshes during the initial period of a first frame and changing the refresh period after performing the multiple refreshes and performing refreshes based on the changed refresh period.

[0023] Preferably, the timing controller is configured to change the refresh period for each frame after performing the multiple refreshes.

[0024] Preferably, the timing controller is configured to change the refresh period for each frame during a predetermined number of frames.

[0025] Preferably, the timing controller is configured to: perform a refresh at a first time interval after performing the multiple refreshes in the first frame; and perform a refresh at a second time interval greater than the first time interval in the second frame.

[0026] Preferably, the timing controller is further configured to perform a refresh in the third frame at an interval greater than the second time period.

[0027] Preferably, the timing controller is configured to increase the refresh period as frames progress after performing the multiple refreshes.

[0028] Preferably, the timing controller is configured to: continuously perform multiple refreshes at a first frequency and a predetermined number of times during the initial period of the first frame; perform refreshes at intervals of a first time period during the remaining periods of the first frame; and perform refreshes at intervals of a second time period longer than the first time period during the second frame.

[0029] Preferably, the multiple refreshes are performed at a frequency of 30Hz during the initial period of the first frame, the first period being set to correspond to a period of 10Hz and the second period being set to correspond to a period of 5Hz.

[0030] Preferably, the third time period is set to a period corresponding to a frequency of 2Hz or lower.

[0031] A method for operating a display device according to an embodiment of the present invention may include: performing multiple refreshes during the initial period of a first frame in a low-speed operation mode; performing refreshes at intervals of a first period during the remaining periods of the first frame; and performing refreshes at intervals of a second period longer than the first period during a second frame.

[0032] Preferably, the method further includes: performing a refresh in the third frame at an interval greater than the second time period.

[0033] Preferably, performing multiple refreshes includes: continuously performing refreshes at a first frequency and a predetermined number of times during the initial period of the first frame.

[0034] Preferably, performing a refresh includes: gradually reducing the operating frequency of the display device in the low-speed operating mode.

[0035] Preferably, the multiple refreshes are performed at a frequency of 30Hz during the initial period of the first frame, the first period being set to correspond to a period of 10Hz and the second period being set to correspond to a period of 5Hz.

[0036] Preferably, the third time period is set to a period corresponding to a frequency of 2Hz or lower.

[0037] According to some embodiments of the present invention, the refresh cycle can be changed in a low-speed operating mode, thereby improving response characteristics.

[0038] Furthermore, according to some embodiments of the present invention, the target level of image data fed into the pixels can be maintained in a low-speed operating mode.

[0039] Furthermore, according to some embodiments of the present invention, even if the operating characteristics change due to component hysteresis, short-cycle operation can be performed, thereby reducing the amount of change and thus reducing brightness variation, thereby maintaining the target level.

[0040] Furthermore, according to some embodiments of the present invention, response characteristics can be improved and target levels can be maintained in low-speed operating modes, thereby improving image quality.

[0041] Furthermore, according to some embodiments of the present invention, low-speed operation can be achieved while maintaining image quality, thereby reducing power consumption.

[0042] The effects of the present invention are not limited to those described above, and those skilled in the art will clearly understand from the following description other effects not mentioned.

[0043] The objectives, solutions, and effects of the present invention described above do not specify the essential features of the claims. Therefore, the scope of the claims is not limited by the objectives, solutions, and effects of the above description.

[0044] It should be understood that the foregoing general description and the following detailed description of the present invention are illustrative and explanatory, and are intended to provide further explanation of the claimed inventive concept. Attached Figure Description

[0045] The accompanying drawings, which provide a further understanding of the invention and are incorporated in and form a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0046] Figure 1 This is a block diagram schematically illustrating a display device according to an embodiment.

[0047] Figure 2 This is a circuit diagram illustrating an example of a pixel in a display device according to an embodiment of the present invention.

[0048] Figure 3 This is a timing diagram illustrating a method for operating a display device according to a first embodiment of the present invention.

[0049] Figure 4 It is a graph showing the change in brightness over time during low-speed operation of the display device according to the first embodiment of the present invention.

[0050] Figure 5 This is a graph showing the change in actual product brightness via photodiodes in a display device according to a first embodiment of the present invention.

[0051] Figure 6 This is a graph illustrating the response characteristics of a display device according to a first embodiment of the present invention.

[0052] Figure 7 This is a timing diagram illustrating a method for operating a display device according to a second embodiment of the present invention.

[0053] Figure 8 This is a graph showing the changes in response characteristics and brightness over time in the low-speed operation mode of the display device according to the second embodiment of the present invention.

[0054] Throughout the accompanying drawings and detailed description, unless otherwise stated, the same reference numerals should be understood to refer to the same elements, features, and structures. For clarity, illustrative purposes, the relative dimensions and depictions of these elements may be enlarged. Detailed Implementation

[0055] The invention will now be described in detail with reference to embodiments thereof, some of which are illustrated in the accompanying drawings. In the following description, detailed descriptions of well-known functions or constructions relevant to this document will be omitted where such description would be deemed unnecessary to obscure the spirit of the inventive concept. The described process steps and / or operations are exemplary, and the order of steps and / or operations is not limited to the order set forth herein, but may be varied as is known in the art, unless the steps and / or operations must occur in a particular order. Similar reference numerals refer to similar elements throughout the application. The names of the elements used in the following description have been chosen solely for ease of description, and therefore these names may differ from those used in actual products.

[0056] See below and appendix for reference. Figure 1 The advantages, features, and implementation methods of the present invention will become clear from the described embodiments. However, the present invention can be implemented in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that the disclosure of the present invention is thorough and complete and fully conveys the scope of the invention to those skilled in the art. Furthermore, the present invention is defined only by the scope of the claims.

[0057] The shapes, dimensions, ratios, angles, quantities, etc., disclosed in the drawings for the purpose of describing embodiments of the invention are merely exemplary, and therefore the invention is not limited to the details illustrated. Throughout the application, the same reference numerals refer to the same elements. In the following description, detailed descriptions of related known functions or constructions will be omitted where it is determined that such detailed descriptions would unnecessarily obscure the focus of the invention. Where the terms "comprising," "having," and "including" are used in the description in this application, additional portions may be added unless "only" is used.

[0058] When interpreting an element, even if there is no explicit statement about the range of error or tolerance, the element should be interpreted as including such a range of error or tolerance.

[0059] It will be understood that when an element or layer is referred to as being "connected to" or "joined to" another element or layer, it may be directly disposed on the other element or layer, or directly connected to or joined to the other element or layer, or one or more intermediate elements or layers may be present. Furthermore, it will be understood that when an element or layer is referred to as being "between" two elements or layers, there may be only that element or layer between the two elements or layers, or one or more intermediate elements or layers may be present.

[0060] When describing temporal relationships, such as when time sequence is described as “after,” “following,” “next,” and “before,” discontinuous situations may be included unless more restrictive terms such as “exactly,” “immediately after,” or “directly” are used.

[0061] When describing positional relationships, for example, when the positional relationship between two parts is described as “on top of,” “above,” “below,” and “after,” one or more additional parts may be placed between the two parts, unless more restrictive terms such as “exactly” or “directly” are used.

[0062] 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 portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, or portion from another. Therefore, without departing from the spirit and scope of the invention, the first element, component, region, layer, or portion described below may be referred to as the second element, component, region, layer, or portion.

[0063] In describing the elements of the present invention, terms such as first, second, A, B, (a), (b), etc., may be used. These terms are intended to distinguish the corresponding element from other elements, and they do not limit the basis, order, or number of the corresponding elements. Regarding expressions indicating that an element or layer is “connected to,” “joined to,” or “adhered to” another element or layer, the element or layer may be directly connected or adhered to the other element or layer, or indirectly connected or adhered to the other element or layer via one or more intermediate elements or layers disposed or inserted between the elements or layers, unless otherwise described.

[0064] The term "at least one" should be understood to include any one and all combinations of one or more of the relevant listed items. For example, "at least one of the first, second and third items" means a combination of all items derived from two or more of the first, second and third items, as well as the first, second or third item.

[0065] For ease of description, the dimensions and thickness of each component shown in the accompanying drawings are illustrated, but the invention is not limited to the dimensions and thickness of the illustrated components.

[0066] When describing signal flow relationships, when transmitting a signal, for example, "from node A to node B", the signal can be transmitted from node A to node B via another node, unless terms such as "immediately" or "directly" are used.

[0067] Those skilled in the art will fully understand that the features of the various embodiments of the present invention can be combined or integrated with each other, either partially or entirely, and can be technically interoperable and driven in various ways. The embodiments of the present invention can be implemented independently of each other, or implemented together in an interdependent relationship.

[0068] Unless otherwise defined, all terms used herein, including technical and scientific terms, shall have the same meaning as commonly understood by one of ordinary skill in the art to which the inventive concept pertains. It will also be understood that terms such as those defined in common dictionaries shall be interpreted as having the same meaning as their meaning in the context of the relevant field, and shall not be interpreted in an idealized or overly formalized manner unless expressly defined herein.

[0069] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. For ease of description, the scale of each element shown in the drawings may differ from the actual scale, and is therefore not limited to the scale illustrated.

[0070] Below, we disclose a display device capable of changing the refresh cycle to improve responsiveness during low-speed operation, and a method for operating the display device.

[0071] Before describing the display device and the method of operating the display device according to embodiments of the present invention, the meanings of the terms used herein are defined.

[0072] As used in this article, low-speed operation can be defined as operation of the display panel at an operating frequency of 1 Hz. However, the operating frequency in low-speed operation is not limited to 1 Hz.

[0073] As used in this article, the phrase "refresh operation" can be defined as the operation of writing data voltages corresponding to the same image data to pixels on the display panel in a low-speed operation.

[0074] As used herein, the term "multiple refresh" can be defined as the operation of repeatedly writing data voltages corresponding to the same image data to the pixels of the display panel.

[0075] Figure 1 This is a block diagram schematically illustrating a display device according to an embodiment.

[0076] Reference Figure 1 According to one embodiment of the present invention, a display device 1000 may include: a display panel 100 including pixels P; a panel driving circuit that drives signal lines connected to pixels P; and a timing controller 400 for the control panel driving circuit.

[0077] The panel driving circuit can write image data to the pixel P of the display panel 100. The panel driving circuit may include a source driver 200 for driving the data lines connected to the pixel P and a gate driver 300 for driving the gate lines GL and light-emitting lines EL connected to the pixel P.

[0078] The panel driving circuit can operate in a low-speed operation mode. This low-speed operation mode is activated when analysis of the input image determines that the image remains unchanged within a preset number of frames—that is, when a still image is input for a defined duration or longer. In low-speed operation mode, the operating frequency of the panel driving circuit is reduced, extending the write cycle for writing image data to pixels and thus reducing power consumption.

[0079] In low-speed operation mode, the refresh rate at which image data is updated on the display panel 100 can be lower than the refresh rate in the default operation mode. For example, if the operation frequency in the default operation mode is 60Hz, the operation frequency in low-speed operation mode can be 1Hz.

[0080] The activation of the low-speed operation mode is not limited to the case of inputting a still image. For example, the panel drive circuit can operate in the low-speed operation mode when the display device 1000 is operating in standby mode or when a user command or input image has not been input to the panel drive circuit for a predetermined time or longer.

[0081] Multiple data lines and multiple gate lines can be arranged in the display panel 100, intersecting each other. Pixels P can be arranged in a matrix in the display panel 100. Data voltages corresponding to image data can be written to the pixel array of the display panel 100.

[0082] Each pixel P may consist of a red sub-pixel, a green sub-pixel, and a blue sub-pixel for color representation. Optionally, a pixel may further include a white sub-pixel. Data lines, gate lines, and power lines may be connected to each pixel P.

[0083] In default operating mode, source driver 200 can convert image data Da received from timing controller 400 into data voltage in each frame and then supply the data voltage to the data line. Source driver 200 may include a digital-to-analog converter (DAC) for converting image data Da into data voltage.

[0084] In low-speed operation mode, the source driver 200 can reduce its operating frequency under the control of the timing controller 400. For example, in the default operation mode, the source driver 200 can output a data voltage corresponding to the image data during each frame period. In low-speed operation mode, the source driver 200 can output the data voltage for a portion of each frame and stop outputting the data voltage for the remainder of each frame. Therefore, the operating frequency and power consumption of the source driver 200 in low-speed operation mode can be significantly lower than in the default operation mode.

[0085] The gate driver 300 can output a scan signal under the control of the timing controller 400 to select the pixel P that is charged with data voltage. The gate driver 300 can be implemented as a shift register and shifts the scan signal and sequentially provides the scan signal to the gate lines.

[0086] Furthermore, the gate driver 300 can output a light-emitting signal under the control of the timing controller 400 to control the light-emitting timing of the pixel P charged with data voltage. The gate driver 300 may include a shift register and an inverter, and can shift the light-emitting signal and sequentially provide the light-emitting signal to the light-emitting lines.

[0087] The gate driver 300 can be used with the pixel array and formed directly on the substrate of the display panel 100 using the GIP (in-panel driver) process.

[0088] The timing controller 400 may include a low-speed operation control module for reducing the operating frequency of the panel drive circuitry. In the default operating mode, the timing controller 400 can control the operating timing of the panel drive circuits 200 and 300 using a frame frequency obtained by multiplying the frame frequency by a positive integer.

[0089] The timing controller 400 can reduce the operating frequency of the panel driving circuits 200 and 300 in a low-speed operation mode. For example, the timing controller 400 can reduce the operating frequency of the panel driving circuits 200 and 300 so that the write cycle for writing image data Da to pixel P is 1 second. The frequency in the low-speed operation mode is not limited to 1Hz. In the low-speed operation mode, pixel P of the display panel 100 is not charged with new data voltage for most of the significant duration of a frame, but instead retains the already charged data voltage.

[0090] The timing controller 400 can generate a data timing control signal DCS for controlling the operating timing of the source driver 200 and a gate timing control signal SCS for controlling the operating timing of the gate driver 300 based on the timing signals Vsync, Hsync, DE, and CLK received from the host system. The timing control signal generated by the timing controller 400 in the default operating mode may be different from the timing control signal generated by the timing controller 400 in the low-speed operating mode.

[0091] In low-speed operation mode, timing controller 400 can control system drive circuits 200 and 300 to perform multiple refreshes during the initial period of the first frame, and change the refresh period to perform refreshes after multiple refreshes.

[0092] The timing controller 400 can continuously perform multiple refreshes at a first frequency and a determined (or predetermined) number of times during the initial period of the first frame, perform refreshes at intervals of the first period after the initial period of the first frame, and perform refreshes at intervals of the second period during the second frame that are longer than the first period.

[0093] Regarding this, the first frequency can be set to 30Hz. The first period can be set to the period corresponding to the second frequency of 10Hz. The second period can be set to the period corresponding to the third frequency of 5Hz.

[0094] For example, the timing controller 400 may continuously perform multiple refreshes at 30Hz during the initial period of the first frame. After performing multiple refreshes, the timing controller 400 may perform refreshes at intervals corresponding to a second frequency of 10Hz for the remainder of the first frame. In the second frame, the timing controller may perform refreshes at intervals corresponding to a third frequency of 5Hz.

[0095] Then, the timing controller 400 may perform a refresh during the third frame at a fourth time interval corresponding to a fourth frequency of 2Hz or lower. In this way, the timing controller 400 may change the refresh period for each frame during a preset (or predetermined) number of frames, such that the refresh period increases over time.

[0096] Figure 2 This is a circuit diagram illustrating an example of a pixel in a display device according to an embodiment of the present invention.

[0097] exist Figure 2 For ease of illustration, a pixel consisting of a 6T1C structure is shown as an example. Alternatively, pixels with structures such as 3T1C, 4T1C, 5T1C, and 7T1C can be used.

[0098] Reference Figure 2 Pixel P may include a first switching transistor T1, a driving transistor T2, a second switching transistor T3, first and second light-emitting transistors T4 and T5, an initialization transistor T6, a storage capacitor Cst, and a light-emitting diode OD.

[0099] The first switching transistor T1 can be turned on in response to a first gate signal applied via the first gate line GL1, and thus can apply the data voltage provided via the data line DL to the driving transistor T2.

[0100] The source of the first switching transistor T1 can be connected to the data line DL, its gate can be connected to the first gate line GL1, and its drain can be connected to the source of the driving transistor T2, i.e., the third node N3.

[0101] The driving transistor T2 can control the luminous current applied to the light-emitting diode OD based on its gate-source voltage. The gate of the driving transistor T2 can be connected to the second node N2, and its drain is connected to the first node N1.

[0102] The initialization transistor T6 can be turned on in response to a second gate signal applied via the second gate line GL2, thus applying an initialization voltage transmitted via the initialization line IL to the fourth node N4. The gate of the initialization transistor T6 can be connected to the second gate line GL2, its source can be connected to the initialization line IL, and its drain can be connected to the fourth node N4.

[0103] The first light-emitting transistor T4 can control the current path between the first driving voltage VDD (or high-potential driving voltage or power supply line) and the driving transistor T2 in response to a first light-emitting signal applied via the first light-emitting line EL1. The gate of the first light-emitting transistor T4 can be connected to the first light-emitting line EL1, its drain can be connected to the power supply line, and its source can be connected to the drain of the driving transistor T2, i.e., the first node N1.

[0104] The second light-emitting transistor T5 can control the current path between the light-emitting diode OD and the driving transistor T2 in response to a second light-emitting signal applied via the second light-emitting line EL2.

[0105] The light-emitting diode OD can emit light using the light-emitting current supplied from the driving transistor T2. The first electrode (or anode) of the light-emitting diode OD can be connected to the fourth node N4, and its second electrode (or cathode) can receive the second driving voltage VSS (or low-potential driving voltage).

[0106] The second switching transistor T3 can be connected to the gate and drain of the driving transistor T2 and is arranged in a diode connection between the gate and drain of the driving transistor T2. The gate of the second switching transistor T3 is connected to the second gate line GL2.

[0107] The storage capacitor Cst can be connected to the second node N2 and the fourth node N4, and is positioned between the second node N2 and the fourth node N4. The storage capacitor Cst can store and hold the voltage and threshold voltage applied to the gate of the driving transistor T2 until the start of the next refresh cycle.

[0108] Each switching transistor used as a switching element can have a longer off-duration in low-speed operating modes. Therefore, to reduce the off-duration current, i.e., leakage current, of each switching transistor in low-speed operating modes, each switching transistor can be implemented as an oxide transistor comprising an oxide semiconductor material. When the switching transistor is implemented as an oxide transistor, the off-duration current can be reduced to prevent a decrease in the charging voltage of pixel P due to leakage current.

[0109] Each of the driving transistor T2, used as a driving element, and the switching transistor with a short off-time, can be implemented as a polycrystalline silicon transistor comprising polycrystalline semiconductor material. Because polycrystalline silicon transistors have high electron mobility, the current in the light-emitting diode OD can be increased to improve efficiency, thereby reducing power consumption.

[0110] Figure 3 This is a timing diagram illustrating a method for operating a display device according to a first embodiment of the present invention. Figure 4 It is a graph showing the change in brightness over time during low-speed operation of the display device according to the first embodiment of the present invention.

[0111] Reference Figure 3 and Figure 4 The display device 1000 can control the control circuits 200 and 300 in a low-speed operation mode to perform multiple refreshes during the initial period of the first frame.

[0112] The display device 1000 can continuously perform multiple refreshes at a first frequency and a predetermined number of times during the initial period of the first frame in a low-speed operation mode. In this regard, the first frequency can be set to 30Hz, and the predetermined number of times can be set to 6.

[0113] For example, in a low-speed operation mode, the display device 1000 can continuously perform 6 refreshes at a frequency of 30Hz during the initial period of the first frame, and then maintain a frequency of 1Hz.

[0114] Regarding Figure 4 As shown in the brightness changes over time during low-speed operation, it can be identified that the response characteristics are improved when multiple refreshes are enabled, compared to operation with multiple refreshes disabled, during the time it takes for the screen to switch from black to white.

[0115] In this way, the display device 1000 can perform multiple refreshes in a low-speed operation of 1Hz in order to reduce response delay caused by the hysteresis characteristics of the driving transistor of pixel P.

[0116] Figure 5 This is a graph showing the actual product brightness change as seen by a photodiode in a display device according to the first embodiment of the present invention. Figure 6 This is a graph illustrating the response characteristics of a display device according to a first embodiment of the present invention.

[0117] Reference Figure 5 and Figure 6 It can be identified that the average brightness level detected by the photodiode during the first frame is 80%. In addition, it can be identified that continuous brightness changes are detected after refresh or sampling operations.

[0118] It can be identified that during the initial 0.2 seconds of sampling at 30Hz with 6 refreshes during the initial period of the first frame, the operation of the pixel compensation circuit can compensate for the changes in the hysteresis characteristics of the driving transistor within 0.2 seconds. However, it can be identified that after 0.2 seconds, due to the changes in the characteristics of the driving transistor, a continuous decrease in brightness occurs, resulting in a response characteristic delay.

[0119] The display device and the method for operating the display device according to the second embodiment of the present invention can change the refresh cycle in a low-speed operation mode to improve response characteristics.

[0120] Figure 7 This is a timing diagram illustrating a method for operating a display device according to a second embodiment of the present invention. Figure 8 This is a graph showing the changes in response characteristics and brightness over time in the low-speed operation mode of the display device according to the second embodiment of the present invention.

[0121] Reference Figure 7 and Figure 8 According to a second embodiment of the present invention, a method for operating a display device may include: changing the refresh cycle in a low-speed operation mode (i.e., the refresh cycle is variable) and performing a refresh based on the changed refresh cycle.

[0122] The display device 1000 can perform a refresh operation with a shorter refresh cycle in an initial frame with a large initial hysteresis characteristic change, gradually increase the refresh cycle in subsequent frames where the hysteresis characteristic change gradually decreases, and perform a refresh operation based on the gradually increasing refresh cycle in subsequent frames (i.e., increasing the refresh cycle as the frame progresses after performing multiple refreshes), thereby improving the response characteristics.

[0123] In low-speed operation mode, display device 1000 can control the control circuits 200 and 300 to perform multiple refreshes during the initial period of the first frame, and after the multiple refreshes of the first frame, change the refresh period and perform refreshes based on the changed refresh period.

[0124] The display device 1000 can continuously perform multiple refreshes at a first frequency and a determined (or predetermined) number of times during the initial period of the first frame, perform refreshes at intervals of a first period after the initial period of the first frame, and perform refreshes at intervals of a second period longer than the first period during the second frame.

[0125] Regarding this, the first frequency can be set to 30Hz. The first time period can be set to correspond to the period of the second frequency of 10Hz. The second time period can be set to correspond to the period of the third frequency of 5Hz.

[0126] For example, the display device 1000 may continuously perform multiple refreshes at 30Hz during the initial period of the first frame. After performing multiple refreshes, the display device 1000 may perform refreshes at intervals corresponding to a second frequency of 10Hz for the remainder of the first frame. During the second frame, the display device 1000 may perform refreshes at intervals corresponding to a third frequency of 5Hz.

[0127] Then, the display device 1000 can perform a refresh during the third frame at intervals corresponding to a fourth frequency of 2Hz or lower (i.e., a fourth time period).

[0128] In this way, in low-speed operation mode, the display device 1000 can change the refresh period for each frame after performing multiple refreshes or during a preset number of frames, so that the refresh period increases over time.

[0129] When the operating frequency is changed from 60Hz to 1Hz, the display device 1000 can continuously perform multiple refreshes to minimize brightness changes caused by hysteresis fluctuations and gradually reduce the frequency used to determine the refresh cycle.

[0130] Display device 1000 can perform refresh operations at various refresh cycles during the first frame. In one example, display device 1000 can perform multiple refreshes at 60Hz, and can perform n refreshes at intervals of a first time period, m refreshes at intervals of a second time period, and k refreshes at intervals of a third time period, where n, m, and k are positive integers greater than or equal to 2. In this regard, the first time period is not limited to 60Hz and can be set to correspond to frequencies greater than 60Hz or less than 60Hz.

[0131] The second time period can be longer than the first time period, and the third time period can be set to be longer than the second time period.

[0132] In low-speed operation mode, the display device 1000 can improve the impact of the hysteresis characteristics of the driving transistors on the response characteristics, such as improving the response characteristics when the screen changes from black to white, the speed of brightness change, and the latency.

[0133] The display device according to embodiments of the present invention can be described as follows:

[0134] A display device 1000 according to an embodiment of the present invention may include a display panel 100; and panel driving circuits 200 and 300 configured to drive the display panel 100, wherein in a low-speed operation mode, the display device 1000 may control the panel driving circuits 200 and 300 to: perform multiple refreshes during the initial period of a first frame, and then change the refresh period after the multiple refreshes and perform refreshes based on the changed refresh period.

[0135] According to some embodiments of the present invention, the display device 1000 may change the refresh period for each frame after performing the multiple refreshes.

[0136] According to some embodiments of the present invention, the display device 1000 may change the refresh cycle for each frame during a preset number of frames.

[0137] According to some embodiments of the present invention, after performing the multiple refreshes during the first frame, the display device 1000 may perform refreshes at intervals of a first time period; and then perform refreshes at intervals of a second time period longer than the first time period during the second frame.

[0138] According to some embodiments of the present invention, the display device 1000 may perform a refresh during the third frame at an interval greater than the third time period.

[0139] According to some embodiments of the present invention, after performing the multiple refreshes, the display device 1000 may increase the refresh cycle as the frames progress.

[0140] According to some embodiments of the present invention, the display device 1000 may continuously perform multiple refreshes at a first frequency and a determined number of times during the initial period of the first frame; perform refreshes at intervals of a first time period during the remaining period of the first frame; and then perform refreshes at intervals of a second time period longer than the first time period during the second frame.

[0141] In this regard, the first frequency can be set to 30Hz, the first time period can be set to a period corresponding to the second frequency of 10Hz, and the third time period can be set to a period corresponding to the third frequency of 5Hz.

[0142] According to another embodiment of the present invention, a display device 1000 may include: a display panel 100; a source driver 200 for driving data lines of the display panel 100; a gate driver 300 for driving gate lines of the display panel 200; and a timing controller 400, the timing controller 400 being configured to control the source driver 200 and the gate driver 300 in a low-speed operation mode: performing multiple refreshes during the initial period of a first frame and changing the refresh period after performing the multiple refreshes and performing refreshes based on the changed refresh period.

[0143] According to some embodiments of the present invention, the timing controller 400 may change the refresh period for each frame after performing the multiple refreshes.

[0144] According to some embodiments of the present invention, the timing controller 400 can change the refresh period for each frame during a preset number of frames.

[0145] According to some embodiments of the present invention, after performing the multiple refreshes during the first frame, the timing controller 400 may perform refreshes at intervals of a first time period; and perform refreshes at intervals of a second time period longer than the first time period during the second frame.

[0146] According to some embodiments of the present invention, the timing controller 400 may perform a refresh during the third frame at intervals longer than the second time period.

[0147] According to some embodiments of the present invention, after performing the multiple refreshes, the timing controller 400 may increase the refresh period as the frames progress.

[0148] According to some embodiments of the present invention, the timing controller 400 may continuously perform multiple refreshes at a first frequency and a determined number of times during the initial period of the first frame; perform refreshes at intervals of a first period during the remaining period of the first frame; and perform refreshes at intervals of a second period longer than the first period during the second frame.

[0149] According to another embodiment of the present invention, a method of operating a display device may include the following steps: performing multiple refreshes during the initial period of a first frame in a low-speed operation mode; performing refreshes at intervals of a first period during the remaining periods of the first frame; and performing refreshes at intervals of a second period longer than the first period during a second frame.

[0150] According to some embodiments of the present invention, the method may further include the following step: performing a refresh during the third frame at intervals greater than the second time period.

[0151] According to some embodiments of the present invention, the step of performing multiple refreshes may include: continuously performing refreshes at a first frequency and a predetermined number of times during the initial time period of the first frame.

[0152] According to some embodiments of the present invention, when the operation mode of the display device is switched to a low-speed operation mode, the operation frequency of the display device can be gradually reduced.

[0153] According to an embodiment of the present invention, the refresh cycle can be changed in a low-speed operation mode, thereby improving response characteristics.

[0154] Furthermore, according to embodiments of the present invention, the target level of image data fed into the pixels can be maintained in a low-speed operating mode.

[0155] Furthermore, according to embodiments of the present invention, even if the operating characteristics change due to component lag, short-cycle operation can be performed, thereby reducing the amount of change and thus reducing brightness variation, thereby maintaining the target level.

[0156] Furthermore, according to embodiments of the present invention, response characteristics can be improved and target levels maintained in low-speed operation modes, thereby improving image quality.

[0157] Furthermore, according to embodiments of the present invention, low-speed operation can be achieved while maintaining image quality, thereby reducing power consumption.

[0158] In a display device according to an embodiment of the present invention, the subject that changes the refresh cycle during low-speed operation is embodied in a timing controller 400. However, the subject is not limited to this.

[0159] A display device according to an embodiment of the present invention may include a refresh control module for changing the refresh period in a low-speed operation mode. Optionally, the display device may include a refresh control module for changing the refresh period in a low-speed operation mode in the source driver 200 or the gate driver 300.

[0160] Various modifications and variations may be made to this invention without departing from the technical spirit or scope thereof, as will be apparent to those skilled in the art. Therefore, this invention is intended to cover any modifications and variations that fall within the scope of the appended claims and their equivalents.

Claims

1. A display device, comprising: Display panel; as well as A panel driver circuit configured to drive the display panel. In the low-speed operation mode, the display device is configured to control the panel driving circuit to perform multiple refreshes during the initial period of the first frame, and after the multiple refreshes, change the refresh period and perform refreshes based on the changed refresh period. The display device is configured to increase the refresh period as frames progress after the multiple refreshes are performed.

2. The display device according to claim 1, wherein the display device is configured to change the refresh period for each frame after performing the multiple refreshes.

3. The display device according to claim 2, wherein the display device is configured to change the refresh period for each frame during a predetermined number of frames.

4. The display device according to claim 1, wherein the display device is configured to: After performing the multiple refreshes in the first frame, a refresh is performed at intervals of a first time period; and A refresh is performed in the second frame at a second time interval that is longer than the first time interval.

5. The display device according to claim 4, wherein the display device is further configured to: perform a refresh in the third frame at an interval greater than the third time period.

6. The display device according to claim 1, wherein the display device is configured to: Multiple refreshes are performed continuously at a first frequency and a predetermined number of times during the initial period of the first frame; Refreshing is performed at intervals of the first time period during the remaining time period of the first frame; and A refresh is performed in the second frame at a second time interval that is longer than the first time interval.

7. The display device according to claim 6, wherein in the low-speed operation mode of the display panel, the operating frequency of the display device gradually decreases.

8. The display device according to claim 1, wherein the display device is configured to: Multiple refreshes are performed continuously at a first frequency and a predetermined number of times during the initial period of the first frame; During the remaining time periods of the first frame, n refreshes are performed at intervals equal to the first time period; and In the second frame, m refreshes are performed at intervals of the second time period. Where n and m are positive integers greater than or equal to 2.

9. The display device of claim 5, wherein the multiple refreshes are performed at a frequency of 30 Hz during the initial period of the first frame, the first period being configured to correspond to a period of 10 Hz and the second period being configured to correspond to a period of 5 Hz.

10. The display device of claim 9, wherein the third time period is set to a period corresponding to a frequency of 2 Hz or lower.

11. A display device, comprising: Display panel; The source driver is configured to drive the data lines of the display panel; A gate driver configured to drive the gate lines of the display panel; as well as A timing controller configured to control the source driver and the gate driver in a low-speed operating mode: performing multiple refreshes during the initial period of a first frame and changing the refresh period to perform a refresh after performing the multiple refreshes. The timing controller is configured to increase the refresh period as frames progress after the multiple refreshes are performed.

12. The display device of claim 11, wherein the timing controller is configured to change the refresh period for each frame after performing the multiple refreshes.

13. The display device of claim 12, wherein the timing controller is configured to change the refresh period for each frame during a predetermined number of frames.

14. The display device of claim 11, wherein the timing controller is configured to: After performing the multiple refreshes in the first frame, a refresh is performed at intervals of a first time period; and A refresh is performed in the second frame at a second time interval that is longer than the first time interval.

15. The display device of claim 14, wherein the timing controller is further configured to perform a refresh in the third frame at an interval greater than the second time period.

16. The display device of claim 11, wherein the timing controller is configured to: Multiple refreshes are performed continuously at a first frequency and a predetermined number of times during the initial period of the first frame; Refreshing is performed at intervals equal to the first time period during the remaining time period of the first frame; and A refresh is performed in the second frame at a second time interval that is longer than the first time interval.

17. The display device of claim 15, wherein the multiple refreshes are performed at a frequency of 30 Hz during the initial period of the first frame, the first period being configured to correspond to a period of 10 Hz and the second period being configured to correspond to a period of 5 Hz.

18. The display device of claim 17, wherein the third time period is configured to correspond to a period of 2 Hz or lower.

19. A method of operating a display device, the method comprising: In low-speed operation mode, multiple refreshes are performed during the initial period of the first frame; Refreshing is performed at intervals equal to the first time period during the remaining time periods of the first frame; Refreshing is performed during the second frame at intervals longer than the first time period, and... A refresh is performed in the third frame at an interval greater than the second time period.

20. The method of claim 19, wherein performing multiple refreshes comprises: Refreshing is performed continuously at a first frequency and a predetermined number of times during the initial period of the first frame.

21. The method of claim 19, wherein performing a refresh comprises: This causes the operating frequency of the display device to gradually decrease in the low-speed operation mode.

22. The method of claim 19, wherein the multiple refreshes are performed at a frequency of 30 Hz during the initial period of the first frame, the first period being set to correspond to a period of 10 Hz and the second period being set to correspond to a period of 5 Hz.

23. The method of claim 22, wherein the third time period is set to a period corresponding to a frequency of 2 Hz or lower.

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