Method for controlling a display device

Abstract

A method for controlling a display device driven using a PWM signal is provided, the method comprising: obtaining, by a controller, a type of display content to be displayed on the display device; and controlling, by the controller, a duty of a PWM signal driving the display device according to the type of display content; where, if the type of display content is a moving image, the duty of the PWM signal is set to a first value; and, if the type of display content is a still image, the duty of the PWM signal is set to a second value greater than the first value.

Description

[Technical field]

[0001] The present disclosure relates to a method for controlling a display device, a display device, and an apparatus having a display device. [Background technology]

[0002] Recent advances in communication and image processing technologies have enabled users to enjoy a variety of content using electronic devices, such as mobile phones, smartphones, tablet devices, personal computers, television sets, or portable multimedia players. For example, users may use such devices to watch video content, view still images, or read reading material, such as comics, novels, magazines, or newspapers. In this regard, one of the recent technical challenges in the field of display devices is to achieve a desirable display quality regardless of the type of content being played on the device.

[0003] Regarding display devices, the prior art has proposed an organic light-emitting diode (OLED) display that can switch between a pulse-width modulation (PWM) driving mode and a pulse-frequency modulation (PFM) driving mode to reduce power consumption. In the PWM driving mode, each light-emitting element is driven by a PWM signal that each includes at least one pulse within each refresh period of the OLED display, and the pulse width is configured to be smaller than a single refresh period. Furthermore, the prior art has disclosed an OLED display that can drive each light-emitting element in a particular display area with a first PWM signal having a first frequency, and drive the remaining display area with a second PWM signal having a second frequency different from the first frequency.

[0004] The PWM driving mode has an advantage for moving image content because the short display time in each refresh period reduces the motion blur perception. On the other hand, when a still image is displayed on a display device driven in the PWM driving mode, flicker is more easily perceived. Flicker can be reduced by driving in a direct current (DC) driving mode because the signal application period is long enough to make the flicker unnoticeable to the viewer. However, the DC driving mode causes motion blur when moving image content is being displayed. Such a problem can appear not only in OLED displays, but also in liquid crystal displays (LCD), micro LED displays, mini LED displays, etc.

[0005] For these reasons, reduction of both flicker and motion blur is needed to achieve better display quality when a device plays any content type. Summary of the Invention

[0006] The embodiments provide a method for controlling a display device, a display device, and an apparatus having a display device.

[0007] The display device may be an OLED display, an LCD, a micro LED display, a mini LED display, etc. The device may be a mobile device, such as a mobile phone, a smartphone, a tablet computer, or a wearable device. The device may also be a computer, such as a personal computer or a navigation system, or a display device, such as a television or a digital signage system.

[0008] A first aspect of an embodiment provides a method for controlling a display device in a pulse width modulation (PWM) driving mode.

[0009] In a first possible implementation form of the first aspect, the method includes obtaining, by a controller, a type of display content to be displayed on the display device, and controlling, by the controller, a duty of a PWM signal driving the display device according to the type of display content, wherein if the type of display content is a moving image, the duty of the PWM signal is set to a first value, and if the type of display content is a still image, the duty of the PWM signal is set to a second value greater than the first value.

[0010] In general, the larger the duty of the PWM signal, the more easily motion blur is perceived, and the smaller the duty of the PWM signal, the more easily flicker is perceived. Therefore, in a first possible implementation form of the first aspect, the duty of the PWM signal is controlled to change according to the type of display content.

[0011] In an exemplary case, the first value is set to suppress motion blur when a moving image is displayed. In this case, when the content type is switched to a still image, the duty is controlled to change from the first value to a second value. The second value is set to be larger than the first value, so that flicker can be suppressed when a still image is displayed. Similarly, when the content type is switched back to a moving image, the duty is controlled to change from the second value to the first value, thereby suppressing motion blur. In this way, the duty of the PWM signal is maintained at a suitable value according to the content type, thereby achieving improved display quality regardless of the content type.

[0012] A second possible implementation form of the first aspect provides a method according to the first possible implementation form of the first aspect, wherein the first value is configured to increase from a minimum duty to a maximum duty as the brightness level of the display device increases from the first brightness level to a maximum brightness level.

[0013] In a second possible implementation form of the first aspect, when a moving image is displayed, the duty of the PWM signal is maintained at a minimum duty when the luminance level is lower than the first luminance level, and is controlled according to a luminance setting when the luminance level is higher than the first luminance level. According to the second possible implementation form of the first aspect, motion blur can be efficiently suppressed when a moving image is displayed.

[0014] A third possible implementation form of the first aspect provides a method according to the first or second possible implementation form of the first aspect, wherein the second value is configured to increase from a minimum duty to a maximum duty as the brightness level of the display device increases from a minimum brightness level to the second brightness level.

[0015] The first aspect Third In the possible implementation form of the first aspect, when a still image is displayed, the duty of the PWM signal is maintained at a maximum duty when the luminance level is higher than the second luminance level, and is controlled according to the luminance setting when the luminance level is lower than the second luminance level. According to the third possible implementation form of the first aspect, flicker can be efficiently suppressed when a still image is displayed.

[0016] A fourth possible implementation form of the first aspect provides a method according to any one of the first to third possible implementation forms of the first aspect, wherein, when the type of display content changes from a moving image to a still image, the duty of the PWM signal is controlled to gradually increase from a first value to a second value, and, when the type of display content changes from a still image to a moving image, the duty of the PWM signal is controlled to gradually decrease from the second value to the first value.

[0017] According to a fourth possible implementation form of the first aspect, the duty of the PWM signal is changed gradually after the type of display content is switched, thereby making the change of the driving mode less noticeable.

[0018] A fifth possible implementation form of the first aspect provides a method according to any one of the first to fourth possible implementation forms of the first aspect, wherein if the type of the displayed content is a particular type related to reading material, the duty of the PWM signal is set to a third value greater than the first value.

[0019] When reading material is displayed, flicker is easily perceived at all luminance levels in PWM driving. In a fifth possible implementation form of the first aspect, the duty of the PWM signal is set to a third value that is greater than the first value. For example, the third value may be a value that drives the display device substantially in a DC driving mode. Therefore, flicker can be effectively suppressed when reading material is displayed.

[0020] A sixth possible implementation form of the first aspect provides a method according to the fifth possible implementation form of the first aspect, in which, when the type of display content changes from a moving image or a still image to the specific type, the duty of the PWM signal is controlled to gradually increase from a first or second value to a third value, and when the type of display content changes from the specific type to a moving image or a still image, the duty of the PWM signal is controlled to gradually decrease from the third value to the first or second value.

[0021] According to a sixth possible implementation form of the first aspect, the duty of the PWM signal is changed gradually after the type of display content is switched, thereby making the change of the driving mode less noticeable.

[0022] A seventh possible implementation form of the first aspect provides a method according to any one of the first to sixth possible implementation forms of the first aspect, further comprising controlling, by the controller, a pulse frequency of the PWM signal to be equal to a refresh rate when the type of the display content is a video.

[0023] According to a seventh possible implementation form of the first aspect, motion blur can be effectively suppressed when moving images are displayed.

[0024] Optionally, the method may further include obtaining, by the controller, metadata usable to identify a type of displayed content, and determining the type of displayed content based on the obtained metadata.

[0025] Optionally, the method may further include estimating, by the controller, a type of displayed content based on a difference between the current frame and at least one frame prior to the current frame.

[0026] A second aspect of the embodiment provides a display device.

[0027] In a first possible implementation form of the second aspect, the display device includes a display panel, a driver that drives the display panel using a pulse width modulation (PWM) signal, and a controller that controls the driver, wherein the controller is configured to obtain a type of display content to be displayed on the display device and control a duty of the PWM signal that drives the display device according to the type of display content, where if the type of display content is a moving image, the duty of the PWM signal is set to a first value, and if the type of display content is a still image, the duty of the PWM signal is set to a second value greater than the first value.

[0028] According to a first possible implementation form of the second aspect, the duty of the PWM signal is controlled to change according to the type of display content. In an exemplary case, the first value is set to suppress motion blur when a moving image is displayed. In this case, when the content type is switched to a still image, the duty is controlled to change from the first value to a second value. The second value is set to be larger than the first value, so that flicker can be suppressed when a still image is displayed. Similarly, when the content type is switched back to a moving image, the duty is controlled to change from the second value to the first value, thereby suppressing motion blur. In this way, the duty of the PWM signal is maintained at a suitable value according to the content type, thereby achieving improved display quality regardless of the content type.

[0029] A second possible implementation form of the second aspect provides a display device according to the first possible implementation form of the second aspect, wherein the first value is configured to increase from a minimum duty to a maximum duty as the brightness level of the display device increases from the first brightness level to a maximum brightness level.

[0030] In a second possible implementation form of the second aspect, when a moving image is displayed, the duty of the PWM signal is maintained at a minimum duty when the luminance level is lower than the first luminance level, and is controlled according to a luminance setting when the luminance level is higher than the first luminance level. According to the second possible implementation form of the second aspect, motion blur can be efficiently suppressed when a moving image is displayed.

[0031] A third possible implementation form of the second aspect provides a display device according to the first or second possible implementation form of the second aspect, wherein the second value is configured to increase from a minimum duty to a maximum duty as the brightness level of the display device increases from a minimum brightness level to a second brightness level.

[0032] The second aspect ThirdIn the possible implementation form of the second aspect, when a still image is displayed, the duty of the PWM signal is maintained at a maximum duty when the luminance level is higher than the second luminance level, and is controlled according to the luminance setting when the luminance level is lower than the second luminance level. According to a third possible implementation form of the second aspect, flicker can be efficiently suppressed when a still image is displayed.

[0033] A fourth possible implementation form of the second aspect provides a display device according to any one of the first to third possible implementation forms of the second aspect, in which, when the type of display content changes from a moving image to a still image, the controller controls the driver to gradually increase the duty of the PWM signal from a first value to a second value, and, when the type of display content changes from a still image to a moving image, the controller controls the driver to gradually decrease the duty of the PWM signal from the second value to the first value.

[0034] According to a fourth possible implementation form of the second aspect, the duty of the PWM signal is changed gradually after the type of display content is switched, thereby making the change of the driving mode less noticeable.

[0035] A fifth possible implementation form of the second aspect provides a display device according to any one of the first to fourth possible implementation forms of the second aspect, wherein the duty of the PWM signal is set to a third value greater than the first value.

[0036] When reading material is displayed, flicker is easily perceived at all luminance levels in PWM driving. In a fifth possible implementation form of the second aspect, the duty of the PWM signal is set to a third value that is greater than the first value. For example, the third value may be a value that causes the display device to be driven in a substantially DC driving mode. Thus, flicker can be effectively suppressed when reading material is displayed.

[0037] A sixth possible implementation form of the second aspect provides a display device according to the fifth possible implementation form of the second aspect, in which, when the type of display content changes from a moving image or a still image to a specific type, the controller controls the driver to gradually increase the duty of the PWM signal from a first or second value to a third value, and when the type of display content changes from the specific type to a moving image or a still image, the controller controls the driver to gradually decrease the duty of the PWM signal from the third value to the first or second value.

[0038] According to a sixth possible implementation form of the second aspect, the duty of the PWM signal is changed gradually after the type of display content is switched, thereby making the change of the driving mode less noticeable.

[0039] A seventh possible implementation form of the second aspect provides a display device according to any one of the first to sixth possible implementation forms of the second aspect, wherein the controller is further configured to control the pulse frequency of the PWM signal to be equal to the refresh rate when the type of the display content is a moving image.

[0040] According to a seventh possible implementation form of the second aspect, motion blur can be effectively suppressed when moving images are displayed.

[0041] Optionally, the controller may be further configured to obtain metadata usable to identify a type of displayed content, and to identify the type of displayed content based on the obtained metadata.

[0042] Optionally, the controller may be further configured to estimate a type of displayed content based on a difference between a current frame and at least one frame preceding the current frame.

[0043] A third aspect of the embodiment provides an apparatus including a processor and a display device according to any one of the first to seventh possible implementation forms of the second aspect, wherein the processor is configured to input data to the display device for displaying display content.

[0044] A fourth aspect of the embodiment provides a non-transitory computer-readable storage medium storing a computer program for causing a computer to execute a method according to any one of the first to seventh possible implementation forms of the first aspect.

[0045] A fifth aspect of the embodiment provides a computer program causing a computer to execute a method according to any one of the first to seventh possible implementation forms of the first aspect.

[0046] A sixth aspect of an embodiment provides a method of controlling a display device in a pulse width modulation (PWM) drive mode, the method comprising: determining, by a controller, that a type of display content to be displayed on the display device is video; and controlling, by the controller, a frequency of a PWM signal driving the display device to be equal to a refresh rate of the display device.

[0047] A seventh aspect of an embodiment provides a display device having a display panel, a driver for driving the display panel using a pulse width modulation (PWM) signal, and a controller for controlling the driver, the controller comprising: , this Identifying that the type of display content to be displayed on the display device is a video ,table The display device is configured to control the frequency of a PWM signal driving the display device to be equal to the refresh rate of the display device according to the type of content to be displayed.

[0048] An eighth aspect of an embodiment provides an apparatus having a processor and a display device according to the seventh aspect of the embodiment, the processor configured to input data to the display device for displaying display content.

[0049] A ninth aspect of the embodiment provides a non-transitory computer-readable storage medium storing a program for causing a computer to carry out the method according to the sixth aspect of the embodiment. [Brief description of the drawings]

[0050] [Figure 1] FIG. 2 is a schematic block diagram illustrating an exemplary configuration of an apparatus according to an embodiment of the present disclosure. [Diagram 2] 1 illustrates a schematic diagram of an exemplary structure of a display panel according to one embodiment of the present disclosure. [Diagram 3] FIG. 2 is a schematic diagram for explaining DC driving and PWM driving on a display device according to an embodiment of the present disclosure. [Figure 4] FIG. 2 is a schematic diagram for explaining the gaze direction of a viewer who is watching a moving object. [Figure 5A] FIG. 1 is a schematic diagram for explaining motion blur that appears in DC driving. [Figure 5B] 1 is a schematic diagram illustrating suppression of motion blur when PWM driving is applied to a display device; [Figure 6A] 6A-6C are schematic diagrams illustrating a method for controlling the width of each pulse input to a light-emitting element according to an embodiment of the present disclosure. [Figure 6B] 6A-6C are schematic diagrams illustrating a method for controlling the width of each pulse input to a light-emitting element according to an embodiment of the present disclosure. [Figure 6C] 6A-6C are schematic diagrams illustrating a method for controlling the width of each pulse input to a light-emitting element according to an embodiment of the present disclosure. [Figure 7A] FIG. 2 is a schematic diagram for explaining a brightness setting function of a display device according to an embodiment of the present disclosure. [Figure 7B] FIG. 2 is a chart illustrating a preferred driving scheme associated with a combination of content type and brightness setting on a display device according to an embodiment of the present disclosure. [Figure 8A]FIG. 2 is a schematic diagram illustrating a method for controlling PWM duty according to content type and brightness setting according to an embodiment of the present disclosure. [Figure 8B] FIG. 2 is a schematic diagram illustrating a method for controlling a voltage corresponding to the amplitude of each pulse according to content type and brightness setting, according to an embodiment of the present disclosure. [Figure 9] FIG. 13 is a schematic diagram for illustrating a method for controlling a PWM duty to gradually increase or decrease during a switching period after a content type change according to an embodiment of the present disclosure. [Figure 10] 4 shows a flowchart for explaining the operation of a display device according to an embodiment of the present disclosure. [Figure 11] FIG. 11 is a schematic diagram for explaining control of a PWM frequency according to a modified example of the embodiment. [Figure 12A] 12A and 12B are schematic diagrams for explaining a method for controlling a PWM frequency according to a refresh rate according to a modified example of an embodiment. [Figure 12B] 12A and 12B are schematic diagrams for explaining a method for controlling a PWM frequency according to a refresh rate according to a modified example of an embodiment. [Figure 13] 13 shows a flowchart for explaining the operation of a display device according to a modified example of the embodiment. [Figure 14] 1 shows a flowchart illustrating a first method for identifying a content type according to an embodiment of the present disclosure. [Figure 15A] 15A and 15B show a flowchart illustrating a second method for identifying a content type according to an embodiment of the present disclosure. [Figure 15B] 15A and 15B show a flowchart illustrating a second method for identifying a content type according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0051] The technical solutions of the embodiments are described below with reference to the accompanying drawings. It is understood that the embodiments described below are only a part, not all, of the embodiments related to the present disclosure. It should be noted that, based on the embodiments described below, all other embodiments that can be derived by those skilled in the art without creative efforts shall fall within the protection scope of the present disclosure.

[0052] The embodiments described below relate to a method for controlling a display device, a display device, and an apparatus in which the display device is provided, and in particular to a method for controlling a display device in a pulse width modulation (PWM) driving mode.

[0053] (Equipment configuration) Fig. 1 is a schematic block diagram for explaining an exemplary configuration of a device according to an embodiment of the present disclosure. A device 10 shown in Fig. 1 is an example of a device according to an embodiment of the present disclosure.

[0054] For example, the device 10 may be an electronic device such as a mobile phone, a smartphone, a tablet device, a personal computer, a television receiver, a portable multimedia player, a wearable device, a digital signage system, or a navigation system, etc. These are merely examples and are not intended to limit the scope of devices to which the techniques of the embodiments described herein can be applied.

[0055] 1, device 10 includes a display device 11, a processor 12, and a memory 13. Optionally, device 10 may further include communication circuitry, such as radio frequency circuitry, that may be used for wired and / or wireless communication interfaces, optical communication interfaces, or the like.

[0056] For example, the display device 11 may be an OLED display, an LCD, a micro LED display, or a mini LED display, etc. The processor 12 may be a central processing unit (CPU), a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), or a graphics processing unit (GPU), etc. The memory 13 may be a read only memory (ROM), a random access memory (RAM), a hard disk drive (HDD), a solid state drive (SSD), or a flash memory, etc.

[0057] The processor 12 is configured to control the operation of the device 10. For example, the processor 12 may execute operations to display content on the display device 11 according to a program stored in the memory 13. In some exemplary cases, the program may be provided via a non-transitory computer-readable storage medium or via a network, such as a local area network, a wide area network, or a combination of these networks.

[0058] In the example of FIG. 1, the display device 11 includes a display panel 111 , a driver 112 , and a controller 113 .

[0059] When the display device 11 is an OLED display, the display panel 111 includes a number of pixels, each having at least one light emitting (LE) element, as shown in Figure 2. Figure 2 illustrates a schematic diagram of an exemplary structure of a display panel according to one embodiment of the present disclosure.

[0060] In the active matrix type, the LE elements are OLEDs, and each LE element is driven by a thin film transistor (TFT) placed at the location of the LE element. Scan lines and signal lines are arranged to cross each LE element and connect to the TFT, and voltage pulses (SIG1, ..., SCN1, ...) pass through the scan lines and signal lines to operate the TFT.

[0061] 2 is merely an example, and is not intended to limit the range of display panels to which the technology of the embodiments described herein can be applied. For example, the technology of the embodiments can be applied to a passive matrix display, an LCD, a micro LED display, a mini LED display, or the like.

[0062] The driver 112 controls voltage pulses through signal lines according to image signals from the controller 113 to display content on the display panel 111. The driver 112 may also control the width and / or frequency of voltage pulses through scan lines and / or signal lines according to instructions from the controller 113. The controller 113 controls the driver 112 to drive the display panel 111 in a PWM driving mode or a DC driving mode, and to change the duty of the PWM signal according to the type of content to be displayed on the display panel 111, as described below.

[0063] In the DC driving mode, the LE elements are controlled to maintain a luminance level according to the image for an entire refresh period. The refresh period here means the period from the latest update of the entire display area on the display panel 111 to the next update of the entire display area on the display panel 111. If the refresh rate of the display panel 111 is synchronized with the frame rate of the video, the refresh period is equal to the length of one frame. For simplicity, the following description will proceed based on this exemplary case, and the terms "refresh period" and "frame" may be used interchangeably hereinafter, regardless of the type of content displayed on the display panel 111.

[0064] In the PWM driving mode, the brightness level of the LE element is controlled based on an image and a PWM pulse sequence in which the width of each PWM pulse is smaller than the length of one frame as shown in Fig. 3. Fig. 3 is a schematic diagram for explaining DC driving and PWM driving on a display device according to an embodiment of the present disclosure. In Fig. 3, the solid line indicates the brightness level in the DC driving mode, and the dashed line indicates the PWM pulse sequence in the PWM driving mode.

[0065] In the example of FIG. 3, one PWM pulse appears in each frame (e.g., frame #1, frame #2, ...), and the width of the PWM pulse (abbreviated as "PWM width") is configured to be smaller than the width of each frame. If the PWM width is W and the width of each frame is Wmax, the duty of the PWM pulse (abbreviated as "PWM duty") is defined by W / Wmax. Optionally, the PWM duty (D) may be defined as the following formula: D=100*W / Wmax[%], which represents the percentage of the PWM pulse in one frame. When D=100[%], the driving mode of the display panel 111 is substantially equivalent to a DC driving mode.

[0066] (Flicker and Motion Blur) Next, a description will be given of flicker that is perceived when a still image is displayed in the PWM drive mode, and motion blur that is perceived when a moving image is displayed in the DC drive mode.

[0067] As mentioned above, in the PWM drive mode, the PWM duty may be less than 100%. When a still image is displayed, the image is displayed continuously at the same position over multiple frames until image replacement occurs. In the DC drive mode, the image is displayed continuously over the entire period of multiple frames, thereby avoiding flicker. In the PWM drive mode, the image is displayed only during a portion of each of the multiple frames, resulting in flicker that is easily perceived, especially in the case of a small PWM duty.

[0068] On the other hand, the PWM driving mode has advantages with regard to suppressing the motion blur that may be perceived when moving images are displayed.

[0069] When a viewer is watching a content including a moving object, the viewer's gaze direction follows the moving object being displayed, as shown in FIG. 4. FIG. 4 is a schematic diagram for explaining the gaze direction of a viewer watching a moving object. In the example of FIG. 4, the moving object OBJ moves from left to right in the display area during the movement period, from TS to TE. Although the display positions of the moving object corresponding to each of the multiple frames during the movement period are discrete, the gaze direction moves continuously from left to right, and the viewer may recognize it as if the moving object is moving continuously. At this time, the viewer's brain creates an afterimage to complement the moving object at the intermediate position between adjacent frames.

[0070] In the DC driving mode, as shown in FIG. 5A, the real image of the moving object is displayed at a position different from the afterimage in most of each frame in the moving period. Therefore, motion blur is easily perceived in the DC driving mode. FIG. 5A is a schematic diagram for explaining the motion blur that appears in the DC driving. In the PWM driving mode, the real image of the moving object is displayed only during a part of each frame, and as a result, the period in which the real image away from the afterimage is displayed is short. Therefore, as shown in FIG. 5B, motion blur is not easily perceived in the PWM driving mode. FIG. 5B is a schematic diagram for explaining the suppression of motion blur when the PWM driving is applied to the display device.

[0071] As described above, the larger the PWM duty, the more easily motion blur is perceived, and the smaller the PWM duty, the more easily flicker is perceived. Therefore, in an embodiment of the present disclosure, the PWM duty is controlled by the controller 113 to vary according to the type of content being displayed.

[0072] Specifically, the controller 113 is configured to obtain a type of content to be displayed, and control, according to the obtained content type, a PWM duty for driving the display panel 111 via the driver 112. If the content type is a moving image, the PWM duty can be set to a first value, and if the content type is a still image, the PWM duty can be set to a second value greater than the first value.

[0073] In an exemplary case, the controller 113 can set the PWM duty to 20% when a moving image is displayed (see FIG. 6C), and can set the PWM duty to 100% when a still image is displayed (see FIG. 6A). The controller 113 can also set the PWM duty to 60% when a still image is displayed (see FIG. 6B). FIGS. 6A-6C are schematic diagrams for explaining a method of controlling the width of each pulse input to a light-emitting element according to an embodiment of the present disclosure. When changing the PWM duty, the controller 113 can control the luminance value of each PWM pulse according to the PWM duty so as to maintain the total luminance value in a frame at a given value based on the luminance setting.

[0074] The brightness setting may be implemented on a brightness setting screen as shown in Fig. 7A. Fig. 7A is a schematic diagram for explaining a brightness setting function of a display device according to an embodiment of the present disclosure. For example, when a viewer operates device 10 to call up the brightness setting function of device 10, a brightness setting screen is displayed on display panel 111. In the example of Fig. 7A, the brightness setting screen includes a bar for changing the brightness setting and a current brightness level (e.g., 60%), and the viewer can change the brightness level by sliding the bar.

[0075] The controller 113 may vary the PWM duty according to both the content type and the brightness setting, as shown in Figure 7B, which is a chart for illustrating a preferred driving scheme associated with a combination of content type and brightness setting on a display device according to an embodiment of the present disclosure.

[0076] 7B, the controller 113 may drive the display panel 111 in a PWM drive mode with a low PWM duty when the luminance level is set to a value within a low range (Low) and the content type is a moving image (Type #1) or a still image (Type #2). Also, the controller 113 may drive the display panel 111 in a PWM drive mode with a high PWM duty when the luminance level is set to a value within a high range (High) and the content type is a moving image (Type #1).

[0077] When the brightness level is set to a value within the middle range (Middle) and the content type is a moving image (Type #1) or a still image (Type #2), the controller 113 may drive the display panel 111 in a PWM drive mode with a medium PWM duty. When the brightness level is set to a value within the high range (High) and the content type is a still image (Type #2), the controller 113 may drive the display panel 111 in a DC drive mode that corresponds to a PWM duty of 100%.

[0078] When the content type is reading material (type #3), such as comics, novels, magazines, or newspapers, flicker is easily noticeable in the PWM drive mode regardless of the brightness setting. Therefore, the controller 113 may drive the display panel 111 in the DC drive mode regardless of the brightness setting when the content type is reading material (type #3). The brightness in such reading material is usually expressed by using a grayscale image (e.g., a screen tone) that is displayed in two levels of "white" and "black". Therefore, when displaying such reading material, higher bit precision is not required, and the DC drive mode is always acceptable.

[0079] Optionally, the PWM duty may be controlled by the method shown in Figure 8A, which is a schematic diagram for illustrating a method for controlling the PWM duty according to the content type and brightness setting according to an embodiment of the present disclosure.

[0080] In FIG. 8A, the solid line and the circle mark above it indicate the control method of PWM duty when the content type is type #1 (moving image), the dotted line and the square mark above it indicate the control method when the content type is type #2 (still image), and the dashed line and the cross mark above it indicate the control method when the content type is type #3 (reading material).

[0081] Referring to the solid line in Fig. 8A, the PWM duty is configured to increase from a minimum duty (e.g., 10%) to a maximum duty (e.g., 100%) as the brightness level set by the brightness setting increases from a first brightness level (e.g., 50%) to a maximum brightness level (e.g., 100%). The controller 113 may control the PWM duty according to the solid line in Fig. 8A when the content type is Type #1.

[0082] Referring to the dashed line in FIG. 8A, the PWM duty is configured to increase from a minimum duty (e.g., 10%) to a maximum duty (e.g., 100%) as the brightness level set by the brightness setting increases from a minimum brightness level (e.g., 10%) to a second brightness level (e.g., 50%). In the example of FIG. 8A, the first brightness level is equal to the second brightness level, but the first brightness level may be different from the second brightness level. The controller 113 may control the PWM duty according to the dashed line in FIG. 8A when the content type is Type #2.

[0083] Referring to the dashed line in Fig. 8A, the PWM duty is configured to be the maximum duty (e.g., 100%) regardless of the brightness setting. When the content type is Type #3, the controller 113 may control the PWM duty according to the dashed line in Fig. 8A. That is, when reading material is displayed, the controller 113 may control the display panel 111 to drive in the DC driving mode.

[0084] When the controller 113 controls the PWM duty according to the method shown in Fig. 8A, the controller 113 may also control the voltage corresponding to the amplitude of each PWM pulse so as to maintain the brightness level set by the brightness setting in each frame, as shown in Fig. 8B, which is a schematic diagram for explaining a method of controlling the voltage corresponding to the amplitude of each pulse according to the content type and the brightness setting, according to an embodiment of the present disclosure.

[0085] According to the above-mentioned method, flicker can be suppressed when still images or reading material are displayed, and motion blur can be suppressed when moving images are displayed, thereby effectively improving the display quality regardless of the content type.

[0086] (Switching method) Next, a switching scheme for switching between the control methods of the PWM duty shown in Fig. 8A will be described with reference to Fig. 9. Fig. 9 is a schematic diagram for explaining a method for controlling the PWM duty to gradually increase or decrease during a switching period after a content type change according to an embodiment of the present disclosure.

[0087] 9, the solid line represents an exemplary case where the brightness level is set to 60% and the content type changes from type #1 (moving image) to type #2 (still image), and the dashed line represents another exemplary case where the brightness level is set to 20% and the content type changes from type #3 (reading material) to type #2 (still image). Also, T1 is the start time of the switching operation, T2 is its end time, and the switching period is the duration of the switching operation.

[0088] 9, the PWM duty at T1 is a value under a first condition where the brightness level is set to 60% and the content type is type #1, and the PWM duty at T2 is a value under a second condition where the brightness level is set to 60% and the content type is type #2. If the PWM duty suddenly changes from the value under the first condition to the value under the second condition, the viewer may feel uncomfortable. Therefore, when the content type changes from type #1 (moving image) to type #2 (still image), the controller 113 may control the driver 112 to gradually increase the PWM duty from the value under the first condition to the value under the second condition, according to the solid line in FIG.

[0089] Similarly, when the content type changes from Type #2 (still image) to Type #1 (video), the controller 113 may control the driver 112 to gradually reduce the PWM duty from the value under the second conditions to the value under the first conditions, in accordance with the solid line in FIG. 9.

[0090] 9, the PWM duty at T1 is a value under a third condition where the brightness level is set to 20% and the content type is type #3, and the PWM duty at T2 is a value under a fourth condition where the brightness level is set to 20% and the content type is type #2. In this case, when the content type changes from type #3 (reading material) to type #2 (still image), the controller 113 may control the driver 112 to gradually decrease the PWM duty from the value under the third condition to the value under the fourth condition, according to the dashed line in FIG.

[0091] Similarly, when the content type changes from type #2 (still image) to type #3 (reading material), the controller 113 may control the driver 112 to gradually increase the PWM duty from the value under the fourth condition to the value under the third condition according to the dashed line in Fig. 9. Furthermore, when the content type changes from type #1 (video) to type #3 (reading material), the controller 113 may similarly control the driver 112 to gradually increase the PWM duty. Also, when the content type changes from type #3 (reading material) to type #1 (video), the controller 113 may similarly control the driver 112 to gradually decrease the PWM duty.

[0092] 9, the PWM duty changes linearly during the switching period, but the controller 113 may control the PWM duty to change nonlinearly. According to the above switching method, the PWM duty changes gradually when switching the content type, thereby reducing discomfort.

[0093] (Display device operation) Next, referring to FIG. 11 10 shows a flowchart for explaining the operation of the display device according to the embodiment of the present disclosure.

[0094] In step S101, controller 113 executes obtaining a type of content to be displayed on display device 11. For example, controller 113 may detect the content type based on metadata obtained from an application program running on device 10. Alternatively, controller 113 may detect the content type based on an analysis of the displayed content.

[0095] In step S102, controller 113 determines whether the content type is type #1 (moving image). If the content type is type #1, the process proceeds to step S103. On the other hand, if the content type is not type #1, the process proceeds to step S104.

[0096] In step S103, controller 113 executes setting the duty of the PWM signal to a first value corresponding to type #1. For example, controller 113 may set the PWM duty based on the solid line in FIG. 8A and the brightness setting of device 10. After completing step S103, the process may proceed to step S101.

[0097] In step S104, controller 113 determines whether the content type is type #3 (reading material). If the content type is type #3, the process proceeds to step S105. On the other hand, if the content type is not type #3, the process proceeds to step S106.

[0098] In step S105, the controller 113 executes setting the PWM duty to a third value corresponding to type #3. For example, the controller 113 may set the PWM duty based on the dashed line in FIG. 8A and the brightness setting of the device 10. In this case, the PWM duty is set to the maximum duty (e.g., 100%) regardless of the brightness setting. After completing step S105, the process may proceed to step S101.

[0099] In step S106, controller 113 executes setting the PWM duty to a second value corresponding to type #2 (still image). For example, controller 113 may set the PWM duty based on the dashed line in FIG. 8A and the brightness setting of device 10. After completing step S106, the process may proceed to step S101.

[0100] As described above, the controller 113 executes controlling the PWM duty according to the content type to be displayed, and the PWM duty is set to a first value when the content type is type #1 (moving image), set to a second value when the content type is type #2 (still image), and set to a third value when the content type is type #3 (reading material). Thus, flicker can be suppressed when still images or reading material are displayed, and motion blur can be suppressed when moving images are displayed, thereby effectively improving the display quality regardless of the content type.

[0101] (Modification of the embodiment) Next, a modification of the embodiment will be described, which relates to the relationship between the PWM frequency and the refresh rate of the display device 11. Here, the PWM frequency can be defined as the number of pulses per second.

[0102] For example, when the PWM frequency is configured to set the number of pulses in one frame to 2 (NP=2), the PWM pulse sequence is as shown in Fig. 11. Fig. 11 is a schematic diagram for explaining the control of the PWM frequency according to a modified example of the embodiment.

[0103] For example, when the refresh rate of the display device 11 is set to 60 Hz and the PWM frequency is also set to 60 Hz, the PWM pulse sequence is as shown in Fig. 12A. That is, when the refresh rate is equal to the PWM frequency, each frame is configured to include one pulse (NP=1). When the refresh rate of the display device 11 is set to 60 Hz and the PWM frequency is set to 240 Hz, each frame is configured to include four pulses (NP=4) as shown in Fig. 12B. Thus, the controller 113 can variably control the number of pulses (NP) in each frame by changing the PWM frequency.

[0104] In a variation of the embodiment, when the content type is type #1 (moving image), the controller 113 controls the PWM frequency so that each frame contains only one pulse, which makes it possible to effectively suppress motion blur, which becomes more noticeable as the number of pulses in each frame increases.

[0105] When the above modification of the embodiment is applied to the operation of the display device shown in Fig. 10, the operation is as shown in Fig. 13. Fig. 13 shows a flowchart for explaining the operation of the display device according to the modification of the embodiment.

[0106] In step S131, controller 113 executes obtaining a type of content to be displayed on display device 11. For example, controller 113 may detect the content type based on metadata obtained from an application program running on device 10. Alternatively, controller 113 may detect the content type based on an analysis of the displayed content.

[0107] In step S132, controller 113 determines whether the content type is type #1 (moving image). If the content type is type #1, the process proceeds to step S133. On the other hand, if the content type is not type #1, the process proceeds to step S135.

[0108] In step S133, the controller 113 executes setting the duty of the PWM signal to a first value corresponding to type #1. For example, the controller 113 may set the PWM duty based on the solid line in FIG. 8A and the brightness setting of the device 10. In step S134, the controller 113 executes obtaining the frame rate of the display device 11 and setting the PWM frequency to the frame rate. After completing step S134, the process may proceed to step S131.

[0109] In step S135, controller 113 determines whether the content type is type #3 (reading material). If the content type is type #3, the process proceeds to step S136. On the other hand, if the content type is not type #3, the process proceeds to step S137.

[0110] In step S136, the controller 113 executes setting the PWM duty to a third value corresponding to type #3. For example, the controller 113 may set the PWM duty based on the dashed line in FIG. 8A and the brightness setting of the device 10. In this case, the PWM duty is set to the maximum duty (e.g., 100%) regardless of the brightness setting. After completing step S136, the process may proceed to step S131.

[0111] In step S137, the controller 113 sets the PWM duty to a second value corresponding to type #2 (still image). For example, the controller 113 may set the PWM duty based on the dashed line in FIG. 8A and the brightness setting of the device 10. After completing step S106, the process may proceed to step S131.

[0112] (First way to identify the content type) Next, a first method for identifying a content type (see S101 in FIG. 10 and S131 in FIG. 13) will be described with reference to Fig. 14. Fig. 14 shows a flowchart for describing the first method for identifying a content type according to an embodiment of the present disclosure.

[0113] In step S141, the controller 113 executes obtaining metadata from an application program running on the device 10. The metadata includes information about the type of content that can be played on the application program.

[0114] In step S142, controller 113 determines whether the metadata indicates "moving image". For example, controller 113 determines that the metadata indicates "moving image" if the application program is a movie player, a video player, a multimedia player capable of playing movies and / or videos, a web browser on which a plug-in program for playing videos runs, or the like. If the metadata indicates "moving image", the process proceeds to step S143. On the other hand, if the metadata does not indicate "moving image", the process proceeds to step S144. In step S143, controller 113 executes the process of determining that the content type is type #1 (moving image).

[0115] In step S144, controller 113 determines whether the metadata indicates a "reader." For example, controller 113 determines that the metadata indicates a "reader" if the application program is a comic book reader, a novel reader, a magazine reader, a newspaper reader, or a reader that can be used to read multiple types of reading material, such as comic books, novels, magazines, or newspapers. If the metadata indicates a "reader," the process proceeds to step S145. On the other hand, if the metadata does not indicate a "reader," the process proceeds to step S146.

[0116] In step S145, controller 113 determines that the content type is type #3 (reading material). In step S146, controller 113 determines that the content type is type #2 (still image).

[0117] (Second way to identify the content type) Next, a second method for identifying a content type (see S101 in FIG. 10 and S131 in FIG. 13) will be described with reference to Figures 15A and 15B. Figures 15A and 15B show flowcharts for describing the second method for identifying a content type according to an embodiment of the present disclosure.

[0118] 15A and 15B, the process between steps S151 and S159 is repeated while varying index n from 1 to N. Index n represents the nth frame among the frames corresponding to a preset period in the displayed target content, where N is a predetermined number of frames that defines the size of the preset period.

[0119] Further, the process between steps S154 and S158 is repeated while varying the index k from 1 to K. The index k represents the kth representative point among the representative points pre-set on the screen on which the target content is displayed, and K is the total number of the representative points.

[0120] In step S151, the controller 113 sets the index n to a value according to the number of repetitions, and in step S152, the controller 113 sets the n-th frame as the current frame.

[0121] In step S153, the controller 113 executes obtaining pixel signals at representative points from the current frame and the previous frame immediately before the current frame. For each representative point, the controller 113 may obtain a pixel signal corresponding to the pixel exactly on that point, or a pixel signal corresponding to a block having the pixel exactly on that point and the pixels surrounding that point.

[0122] In step S154, the controller 113 sets the index k to a value according to the number of iterations. In step S155, the controller 113 calculates the difference in pixel signal at the kth representative point between the current frame and the previous frame. For example, this difference can be calculated using the following formula: X=Abs[P1-P2] where X is the difference, P1 is the pixel signal of the k-th representative point in the previous frame, P2 is the pixel signal of the k-th representative point in the current frame, and Abs[...] denotes the absolute value calculation function.

[0123] In step S156, the controller 113 determines whether the difference X is greater than a first predetermined threshold value TH1. If X > TH1, the process proceeds to step S157. On the other hand, if X ≦ TH1, the process proceeds to step S158.

[0124] In step S157, the controller 113 increments the count value Y by +1 and advances the process to step S158. In step S158, if k = K, the process proceeds to step S159, and if the index k < K, the process returns to step S154. In step S159, if n = N, the process proceeds to step S160, and if n < N, the process returns to step S151.

[0125] In step S160, the controller 113 determines whether the count value Y is greater than a second predetermined threshold value TH2. If Y > TH2, the process proceeds to step S161. On the other hand, if Y ≦ TH2, the process proceeds to step S162. In step S161, the controller 113 executes identifying that the content type is type #1. In step S162, the controller 113 executes identifying that the content type is type #2.

[0126] Using the above first and / or second methods, the controller 113 can identify the content type. However, these methods are merely examples, and other methods may be used to identify the content type. Also, the flowcharts shown in FIGS. 10, 13 - 14, and 15A - 15B are merely examples and are not intended to limit the scope of the embodiments described herein.

[0127] The above disclosure only discloses exemplary embodiments and is not intended to limit the protection scope of the present invention. It should be understood by those skilled in the art that all or part of the above embodiments and other embodiments and modifications that can be derived based on the scope of the claims of the present invention will naturally fall within the scope of the present invention.

Claims

1. 1. A method for controlling a display device in a pulse width modulation (PWM) driving mode, comprising: obtaining, by a controller, a type of display content to be displayed on the display device; controlling, by the controller, a duty of a PWM signal for driving the display device in accordance with the type of the display content, the duty corresponding to a proportion of each refresh period during which the display device displays an actual image; having If the type of the display content is a moving image, the duty of the PWM signal is set to a first value, if the type of the display content is a still image, the duty of the PWM signal is set to a second value greater than the first value, and if the type of the display content is a reading material type associated with a book reader application, the duty of the PWM signal is set to a third value corresponding to 100%; When a brightness level of the brightness setting of the display device is lower than a second brightness level, the second value is set to be smaller than the third value. method.

2. the first value is configured to increase from a minimum duty to a maximum duty as the luminance level increases from a first luminance level to a maximum luminance level; The method of claim 1.

3. the second value is configured to increase from a minimum duty to a maximum duty as the luminance level increases from a minimum luminance level to the second luminance level. The method according to claim 1 or 2.

4. when the type of the display content changes from the moving image to the still image, the duty of the PWM signal is controlled to gradually increase from the first value to the second value; When the type of the display content changes from the still image to the moving image, the duty of the PWM signal is controlled to gradually decrease from the second value to the first value.

4. The method according to claim 1 .

5. When the type of the display content is changed from the moving image or the still image to the reading material type, the duty of the PWM signal is controlled to gradually increase from the first or second value to the third value; When the type of the display content changes from the reading type to the moving image or the still image, the duty of the PWM signal is controlled to gradually decrease from the third value to the first or second value.

5. The method according to any one of claims 1 to 4.

6. The method further includes obtaining, by the controller, metadata usable to identify the type of the displayed content, and identifying the type of the displayed content based on the obtained metadata.

6. The method according to any one of claims 1 to 5.

7. The method further includes estimating, by the controller, the type of the displayed content based on a difference between a current frame of the displayed content and at least one frame prior to the current frame.

6. The method according to any one of claims 1 to 5.

8. The method further comprises controlling, by the controller, a pulse frequency of the PWM signal to be equal to a frame rate of the display content when the type of the display content is the video.

8. The method according to any one of claims 1 to 7.

9. A display device having a display panel, a driver that drives the display panel using a pulse width modulation (PWM) signal, and a controller that controls the driver, the controller is configured to obtain a type of display content to be displayed on the display device, and control a duty of the PWM signal for driving the display panel according to the type of the display content, the duty corresponding to a ratio of a period during which the display panel displays an actual image to a refresh period; If the type of the display content is a moving image, the duty of the PWM signal is set to a first value, if the type of the display content is a still image, the duty of the PWM signal is set to a second value greater than the first value, and if the type of the display content is a reading material type associated with a book reader application, the duty of the PWM signal is set to a third value corresponding to 100%; When a luminance level of a luminance setting of the display device is lower than a second luminance level, the second value is set to be smaller than the third value. Display device.

10. The controller is further configured to obtain metadata usable to identify the type of the displayed content, and to identify the type of the displayed content based on the obtained metadata. The display device according to claim 9.

11. The controller is further configured to estimate the type of the display content based on a difference between a current frame of the display content and at least one frame prior to the current frame. The display device according to claim 9.

12. The controller is further configured to, when the type of the display content is the video, control a pulse frequency of the PWM signal to be equal to a frame rate of the display content. The display device according to any one of claims 9 to 11.

13. 13. An apparatus comprising a processor and a display device according to any one of claims 9 to 12, the processor being configured to input data to the display device for displaying the display content.

14. A non-transitory computer-readable storage medium storing a program for causing a computer to execute the method according to any one of claims 1 to 8.

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