Patent Grant
12106720
This application claims priority to Korean Patent Application No. 10-2021-0116888, filed on Sep. 2, 2021, and all the benefits accruing therefrom under 35 U.S.C. § 119, the content of which in its entirety is herein incorporated by reference.
Embodiments of the invention relate to a display device, and more particularly to a display device performing an alternate driving operation, and a method of operating the display device.
Reduction of power consumption may be desirable in a display device employed in a portable device, such as a smartphone, a tablet computer, etc., for example, in order to extend battery life. In order to reduce the power consumption of the display device, a low frequency driving technique which drives or refreshes a display panel at a frequency lower than a normal driving frequency by analyzing image data is being developed.
In a case where a display device includes a pixel having a great leakage current, for example, a pixel including low-temperature polycrystalline silicon (“LTPS”) p-type metal-oxide-semiconductor (“PMOS”) transistors, a luminance of a display panel driven at a normal driving frequency and a luminance of the display panel driven at a low frequency lower than the normal driving frequency may be different from each other, and a flicker may occur when a driving frequency of the display panel is changed between the normal driving frequency and the low frequency.
Embodiments provide a display device capable of performing an alternate driving operation without a flicker.
Embodiments provide a method of operating a display device capable of performing an alternate driving operation without a flicker.
In an embodiment of the invention, there is provided a display device including a display panel including a plurality of pixel rows, and a panel driver which drives the display panel. The panel driver determines whether input image data represents a still image. When the input image data represents the still image, the panel driver determines a flicker value of the still image, applies a compensation value corresponding to a carry shift interval to the flicker value, determines a driving frequency for the display panel based on the flicker value to which the compensation value is applied, and performs an alternate driving operation for the display panel at the driving frequency.
In an embodiment, to perform the alternate driving operation, the panel driver may divide a frame period into N periods, may divide the plurality of pixel rows into N pixel row groups each including the pixel rows having an interval of N pixel rows, and may sequentially drive the pixel rows included in a corresponding one of the N pixel row groups in each of the N periods, where N is an integer greater than 1.
In an embodiment, the panel driver may include a still image detector which determines whether the input image data represents the still image, and a driving frequency decider which determines the driving frequency for the display panel as a normal driving frequency when the input image data does not represent the still image, and determines the driving frequency for the display panel as a low frequency lower than the normal driving frequency based on the flicker value to which the compensation value is applied when the input image data represents the still image.
In an embodiment, the panel driver may perform a normal driving operation for the display panel at the normal driving frequency when the input image data does not represent the still image, and may perform the alternate driving operation for the display panel at the low frequency when the input image data represents the still image.
In an embodiment, the still image detector may determine whether the input image data represents the still image by comparing the input image data in a previous frame period and the input image data in a current frame period.
In an embodiment, the driving frequency decider may include a flicker lookup table (“LUT”) which stores a plurality of flicker values respectively corresponding to a plurality of gray levels, an image analyzing block which determines a representative gray level of the input image data representing the still image, and determines the flicker value of the still image corresponding to the representative gray level by the flicker LUT, and a carry compensation block which stores the compensation value corresponding to the carry shift interval, applies the compensation value corresponding to the carry shift interval to the flicker value, and determines the driving frequency for the display panel based on the flicker value to which the compensation value is applied.
In an embodiment, the representative gray level of the input image data may be an average value, a maximum value or a minimum value of gray levels represented by a plurality of pixel data included in the input image data.
In an embodiment, the carry compensation block may calculate the flicker value to which the compensation value is applied by multiplying the flicker value by the compensation value.
In an embodiment, the driving frequency decider may include a flicker LUT which stores a plurality of flicker values respectively corresponding to a plurality of gray levels, an image analyzing block which determines a representative gray level of the input image data representing the still image, and determines the flicker value of the still image corresponding to the representative gray level by the flicker LUT, a carry compensation value table which stores a plurality of compensation values respectively corresponding to a plurality of carry shift intervals, and a carry compensation block which reads the compensation value corresponding to the carry shift interval of the alternate driving operation from the carry compensation value table, applies the compensation value corresponding to the carry shift interval to the flicker value, and determines the driving frequency for the display panel based on the flicker value to which the compensation value is applied.
In an embodiment, the panel driver may include a controller which determines the carry shift interval based on an original driving frequency before compensation corresponding to the flicker value of the still image, and generates a carry control signal corresponding to the carry shift interval, and a scan driver including a plurality of stages respectively providing scan signals to the plurality of pixel rows, the scan driver which shifts a carry signal at the carry shift interval in the plurality of stages in response to the carry control signal.
In an embodiment, the controller may determine the carry shift interval by dividing a normal driving frequency by the original driving frequency before compensation.
In an embodiment, the carry control signal may include a first carry control signal corresponding to the carry shift interval having a value of 1, a second carry control signal corresponding to the carry shift interval having a value of 2, a third carry control signal corresponding to the carry shift interval having a value of 3, and a fourth carry control signal corresponding to the carry shift interval having a value of 4. The scan driver may further include a plurality of first switches which sequentially connect the plurality of stages in response to the first carry control signal, a plurality of second switches which connect the plurality of stages at an interval of two stages in response to the second carry control signal, a plurality of third switches which connect the plurality of stages at an interval of three stages in response to the third carry control signal, and a plurality of fourth switches which connect the plurality of stages at an interval of four stages in response to the fourth carry control signal.
In an embodiment of the invention, there is provided a display device including a display panel including a plurality of pixel rows, and a panel driver which drives the display panel and includes a plurality of flicker LUTs respectively corresponding to a plurality of carry shift intervals. The panel driver determines whether input image data represents a still image. When the input image data represents the still image, the panel driver selects a flicker LUT corresponding to a current carry shift interval from among the plurality of flicker LUTs, determines a flicker value of the still image by the selected flicker LUT, determines a driving frequency for the display panel based on the flicker value, and performs an alternate driving operation for the display panel at the driving frequency.
In an embodiment, each of the plurality of flicker LUTs may store a plurality of flicker values respectively corresponding to a plurality of gray levels with respect to a corresponding one of the plurality of carry shift intervals.
In an embodiment, the panel driver may further include a still image detector which determines whether the input image data represents the still image, and a driving frequency decider which determines the driving frequency for the display panel as a normal driving frequency when the input image data does not represent the still image. When the input image data represents the still image, the driving frequency decider may determine a representative gray level of the input image data representing the still image, may select the flicker LUT corresponding to the current carry shift interval from among the plurality of flicker LUTs, may determine the flicker value of the still image corresponding to the representative gray level by the selected flicker LUT, and may determine the driving frequency for the display panel based on the flicker value.
In an embodiment of the invention, there is provided a method of operating a display device. In the method, whether input image data represents a still image is determined, a flicker value of the still image is determined when the input image data represents the still image, a compensation value corresponding to a carry shift interval is applied to the flicker value, a driving frequency for a display panel is determined based on the flicker value to which the compensation value is applied, and an alternate driving operation for the display panel is performed at the driving frequency.
In an embodiment, to perform the alternate driving operation, a frame period may be divided into N periods, a plurality of pixel rows of the display panel may be divided into N pixel row groups each including the pixel rows having an interval of N pixel rows, and the pixel rows included in a corresponding one of the N pixel row groups may be sequentially driven in each of the N periods, where N is an integer greater than 1.
In an embodiment, to determine whether the input image data represents the still image, the input image data in a previous frame period and the input image data in a current frame period may be compared, it may be determined that the input image data does not represent the still image when the input image data in the previous frame period and the input image data in the current frame period are different from each other, and it may be determined that the input image data represents the still image when the input image data in the previous frame period and the input image data in the current frame period are substantially the same as each other.
In an embodiment, to determine the flicker value of the still image, a representative gray level of the input image data representing the still image may be determined, and the flicker value of the still image corresponding to the representative gray level may be determined by a flicker LUT that stores a plurality of flicker values respectively corresponding to a plurality of gray levels.
In an embodiment, to apply the compensation value to the flicker value, the flicker value to which the compensation value is applied may be calculated by multiplying the flicker value by the compensation value.
As described above, in embodiments of a display device and a method of operating the display device, in a case where input image data represents a still image, a flicker value of the still image may be determined, a compensation value corresponding to a carry shift interval of an alternate driving operation may be applied to the flicker value, a driving frequency for a display panel may be determined based on the flicker value to which the compensation value is applied, and the alternate driving operation for the display panel may be performed at the driving frequency. Accordingly, since compensation is performed corresponding to the carry shift interval of the alternate driving operation, a luminance difference between a normal driving operation and the alternate driving operation may be decreased, and a flicker may be prevented.
Further, in embodiments of a display device and a method of operating the display device, in a case where input image data represents a still image, a driving frequency for a display panel may be determined by a plurality of flicker LUTs respectively corresponding to a plurality of carry shift intervals, and an alternate driving operation for the display panel may be performed at the driving frequency. Accordingly, since a flicker LUT corresponding to a current carry shift interval of the alternate driving operation is used, a luminance difference between a normal driving operation and the alternate driving operation may be decreased, and a flicker may be prevented.
Illustrative, non-limiting embodiments will be more clearly understood from the following detailed description in conjunction with the accompanying drawings.
Hereinafter, embodiments of the invention will be explained in detail with reference to the accompanying drawings.
It will be understood that when an element is referred to as being “on” another element, it can be directly on the other element or intervening elements may be therebetween. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present.
It will be understood that, although the terms “first,” “second,” “third” etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, “a first element,” “component,” “region,” “layer” or “section” discussed below could be termed a second element, component, region, layer or section without departing from the teachings herein.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms, including “at least one,” unless the content clearly indicates otherwise. “Or” means “and/or.” As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms “comprises” and/or “comprising,” or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof.
Furthermore, relative terms, such as “lower” or “bottom” and “upper” or “top,” may be used herein to describe one element's relationship to another element as illustrated in the Figures. It will be understood that relative terms are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. In an embodiment, when the device in one of the figures is turned over, elements described as being on the “lower” side of other elements would then be oriented on “upper” sides of the other elements. The exemplary term “lower,” can therefore, encompasses both an orientation of “lower” and “upper,” depending on the particular orientation of the figure. Similarly, when the device in one of the figures is turned over, elements described as “below” or “beneath” other elements would then be oriented “above” the other elements. The exemplary terms “below” or “beneath” can, therefore, encompass both an orientation of above and below.
“About” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). The term “about” can mean within one or more standard deviations, or within ±30%, 20%, 10%, 5% of the stated value, for example.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the invention, and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. A term such as “block” may mean a hardware component such as a circuit, for example.
Referring to
The display panel 110 may include a plurality of data lines, a plurality of scan lines, and the plurality of pixels PX coupled to the plurality of data lines and the plurality of scan lines. In an embodiment, each pixel PX may include at least one capacitor, at least two transistors and an organic light-emitting diode (“OLED”), and the display panel 110 may be an OLED display panel. In an embodiment, the transistors of each pixel PX may be implemented with, but not limited to, low-temperature polycrystalline silicon (“LTPS”) p-type metal-oxide-semiconductor (“PMOS”) transistors, for example. In other embodiments, the transistors of each pixel PX may be implemented with n-type metal-oxide-semiconductor (“NMOS”) transistors, or a combination of the PMOS transistors and the NMOS transistors. In other embodiments, the display panel 110 may be a light-emitting display panel where each pixel PX includes a light-emitting element other than the OLED, for example, a quantum dot (“QD”) light-emitting element. In still other embodiments, the display panel 110 may be a liquid crystal display (“LCD”) panel, or any other suitable display panels.
The data driver 130 may generate the data signals DS based on output image data ODAT and a data control signal DCTRL received from the controller 150, and may provide the data signals DS to the plurality of pixels PX through the plurality of data lines. In an embodiment, the data control signal DCTRL may include, but not limited to, an output data enable signal, a horizontal start signal and a load signal. In an embodiment, the data driver 130 and the controller 150 may be implemented with a single integrated circuit (“IC”), and the IC may be also referred to as a timing controller embedded data driver (“TED”). In other embodiments, the data driver 130 and the controller 150 may be implemented with separate ICs.
The scan driver 140 may generate the scan signals SS based on a scan control signal SCTRL received from the controller 150, and may provide the scan signals SS to the plurality of pixels PX through the plurality of scan lines. In an embodiment, the scan control signal SCTRL may include, but not limited to, a scan start signal and a scan clock signal. In an embodiment, the scan driver 140 may be integrated or formed in a peripheral portion of the display panel 110. In other embodiments, the scan driver 140 may be implemented with one or more ICs.
In an embodiment, the scan control signal SCTRL may further include a carry control signal CCS, and the scan driver 140 may control a carry shift interval (or a carry progress/propagation interval) in response to the carry control signal CCS. In an embodiment, as illustrated in
In an embodiment, in a case where the scan driver 140 receives the first carry control signal CCS1, a first carry signal CR1 generated by a first stage STAGE1 based on a first scan start signal FLM1 may be shifted or transferred to a second stage STAGE2, a second carry signal CR2 generated by a second stage STAGE2 based on the first carry signal CR1 may be shifted or transferred to a third stage STAGE3, a third carry signal CR3 generated by a third stage STAGE3 based on the second carry signal CR2 may be shifted or transferred to a fourth stage STAGE4, and a fourth carry signal CR4 generated by a fourth stage STAGE4 based on the third carry signal CR3 may be shifted or transferred to a subsequent stage (e.g., a fifth stage), for example. That is, the scan driver 140 may shift or transfer the carry signal CR1 through CR4 at the carry shift interval of 1 in response to the first carry control signal CCS1, and the panel driver 120 may perform a normal driving operation that sequentially drives the plurality of pixel rows of the display panel 110 corresponding to the carry shift interval of 1.
In another embodiment, in a case where the scan driver 140 receives the second carry control signal CCS2, the first carry signal CR1 generated by the first stage STAGE1 based on the first scan start signal FLM1 may be shifted or transferred to the third stage STAGE3, and the third carry signal CR3 generated by the third stage STAGE3 based on the first carry signal CR1 may be shifted or transferred to a subsequent stage (e.g., the fifth stage). Further, the second carry signal CR2 generated by the second stage STAGE2 based on a second scan start signal FLM2 may be shifted or transferred to the fourth stage STAGE4, and the fourth carry signal CR4 generated by the fourth stage STAGE4 based on the second carry signal CR2 may be shifted or transferred to a subsequent stage (e.g., a sixth stage). That is, the scan driver 140 may shift or transfer the carry signal CR1 through CR4 at the carry shift interval of 2 in response to the second carry control signal CCS2, and the panel driver 120 may perform an alternate driving operation corresponding to the carry shift interval of 2.
The controller 150 (e.g., a timing controller (“TCON”)) may receive input image data IDAT and a control signal CTRL from an external host processor (e.g., an application processor (“AP”), a graphics processing unit (“GPU”) or a graphics card). In an embodiment, the input image data IDAT may be an RGB image data including red image data, green image data and blue image data. Further, in an embodiment, the control signal CTRL may include, but not limited to, a vertical synchronization signal, a horizontal synchronization signal, an input data enable signal, a master clock signal, etc. The controller 150 may generate the output image data ODAT, the data control signal DCTRL and the scan control signal SCTRL based on the input image data IDAT and the control signal CTRL. The controller 150 may control an operation of the data driver 130 by providing the output image data ODAT and the data control signal DCTRL to the data driver 130, and may control an operation of the scan driver 140 by providing the scan control signal SCTRL to the scan driver 140.
In an embodiment of the display device 100, the panel driver 120 may perform the normal driving operation for the display panel 110 at a normal driving frequency while the display panel 110 displays a moving image, and may perform the alternate driving operation (or an alternate scan driving (“ASD”) operation) for the display panel 110 at a low frequency lower than the normal driving frequency while the display panel 110 displays a still image. Here, the normal driving operation may be an operation that sequentially drives the plurality of pixel rows of the display panel 110, and the alternate driving operation may be an operation that divides one frame period into respective periods, divides the plurality of pixel rows into pixel row groups each including the pixel rows having a predetermined interval and drives one corresponding pixel row group in each of the respective periods.
In an embodiment, to perform the normal driving operation, the controller 150 may provide the first carry control signal CCS1 as the carry control signal CCS to the scan driver 140, the scan driver 140 may shift or transfer the carry signal CR1 through CR4 at the carry shift interval of 1 in response to the first carry control signal CCS1, and the panel driver 120 may perform the normal driving operation corresponding to the carry shift interval of 1. In other embodiments, to perform the normal driving operation, the controller 150 may control the scan driver 140 to sequentially output the scan signals SS by the first and second scan start signals FLM1 and FLM2 and the scan clock signal.
In an embodiment, to perform the alternate driving operation, the panel driver 120 may divide a frame period into N periods, where N is an integer greater than 1. Further, the panel driver 120 may divide the plurality of pixel rows into N pixel row groups. Here, one pixel row may mean one row of the pixels PX connected to the same scan line, and each pixel row group may include the pixel rows having an interval of N pixel rows. Further, in each of the N periods, the panel driver 120 may sequentially drive the pixel rows included in a corresponding one of the N pixel row groups.
In an embodiment, in a case where N is two, the plurality of pixel rows of the display panel 110 may be divided into an odd-numbered pixel row group and an even-numbered pixel row group, for example. In response to the second carry control signal CCS2, the scan driver 140 may connect the odd-numbered stages STAGE1, STAGE3, . . . etc., for the odd-numbered pixel row group to each other, and may connect the even-numbered stages STAGE2, STAGE4, . . . etc., for the even-numbered pixel row group to each other. Thus, odd-numbered carry signals CR1, CR3, . . . etc., may be shifted or transferred within the odd-numbered stages STAGE1, STAGE3, . . . etc., and even-numbered carry signals CR2, CR4, . . . etc., may be shifted or transferred within the even-numbered stages STAGE2, STAGE4, . . . etc. In this case, since the carry signals CR1, CR2, CR3, CR4, . . . etc., of the scan driver 140 are shifted or transferred at an interval of two stages, the carry shift interval of this alternate driving operation may be two stages or 2. Here, the carry shift interval may be an interval between one stage (e.g., the first stage STAGE1) and the next stage (e.g., the third stage STAGE3) to which the carry signal (e.g., the first carry signal CR1) generated by the one stage is shifted or transferred.
The scan driver 140 illustrated in
In a conventional display device, even when a display panel is driven at the low frequency lower than the normal driving frequency, the conventional display device may perform the normal driving operation for the display panel.
In a case where the normal driving operation is performed at the normal driving frequency of about 60 Hz, as illustrated in a first timing diagram 200 of
However, when the display device 100 in embodiments drives the display panel 110 at the low frequency of about 30 Hz, the display device 100 may perform the alternate driving operation for the display panel 110 at the low frequency of about 30 Hz. A frame period FP3 corresponding to the low frequency of about 30 Hz may be a double of the frame period FP1 corresponding to the normal driving frequency of about 60 Hz, and the frame period FP3 may be divided into the first period P1 and the second period P2. As illustrated in a third timing diagram 240 of
However, a luminance of the display device 100 performing the alternate driving operation at the low frequency may not be the same as a luminance of the display device 100 performing the normal driving operation at the normal driving frequency. In an embodiment, as illustrated in the first and third timing diagrams 200 and 240, during the same time length, the number of the pixel rows driven (or for which data writing operations are performed) by the alternate driving operation at about 30 Hz may be less than the number of the pixel rows driven (or for which data writing operations are performed) by the normal driving operation at about 60 Hz, for example. Further, a data writing interval for each pixel PX at the alternate driving operation of about 30 Hz may be longer than a data writing interval for each pixel PX at the normal driving operation of about 60 Hz. Tus, hysteresis of a driving transistor of each pixel PX at the alternate driving operation of about 30 Hz may be different from that at the normal driving operation of about 60 Hz, and luminances of each pixel PX and the display panel 110 at the alternate driving operation of about 30 Hz may be different from those at the normal driving operation of about 60 Hz.
However, in an embodiment of the display device 100, to compensate the luminance 270 at the alternate driving operation, the display device 100 may store a compensation value CV corresponding to a carry shift interval of the alternate driving operation, and may apply the compensation value CV to a flicker value determined using a flicker LUT 160. In an embodiment, the panel driver 120 may determine whether the input image data IDAT represents a still image. Further, in a case the input image data IDAT represents the still image, the panel driver 120 may determine a flicker value of the still image, may apply the compensation value CV corresponding to the carry shift interval of the alternate driving operation to the flicker value, may determine a driving frequency for the display panel 110 based on the flicker value to which the compensation value CV is applied, and may perform the alternate driving operation for the display panel 110 at the driving frequency. In an embodiment, to perform these operations, as illustrated in
The still image detector 170 may determine whether the input image data IDAT represents the still image. In an embodiment, the still image detector 170 may determine whether the input image data IDAT represents the still image by comparing the input image data IDAT in a previous frame period and the input image data IDAT in a current frame period. In an embodiment, the still image detector 170 may determine that the input image data IDAT does not represent the still image or that the input image data IDAT represents a moving image when the input image data IDAT in the previous frame period and the input image data IDAT in the current frame period are different from each other, and may determine that the input image data IDAT represents the still image when the input image data IDAT in the previous frame period and the input image data IDAT in the current frame period are substantially the same as each other, for example.
The driving frequency decider 180 may determine the driving frequency for the display panel 110 as the normal driving frequency when the input image data IDAT does not represent the still image, and may determine the driving frequency for the display panel 110 as the low frequency lower than the normal driving frequency based on the flicker value to which the compensation value CV is applied when the input image data IDAT represents the still image. The normal driving frequency may be a fixed frequency, for example, about 60 Hz, about 120 Hz, about 240 Hz, etc., and the low frequency may be any frequency lower than the normal driving frequency. In an embodiment, the driving frequency decider 180 may include a flicker LUT 160, an image analyzing block 185 and a carry compensation block 190.
The flicker LUT 160 may store a plurality of flicker values respectively corresponding to a plurality of gray levels (e.g., 256 gray levels from a 0-gray level to a 255-gray level). Here, the flicker value may represent a degree of a flicker perceived by a user. In an embodiment, as illustrated in
The image analyzing block 185 may determine a representative gray level of the input image data IDAT representing the still image, may determine the flicker value of the still image corresponding to the representative gray level by the flicker LUT 160, and may determine an original driving frequency before compensation for the display panel 110 according to the flicker value of the still image. In an embodiment, the representative gray level of the input image data IDAT may be, but not limited to, an average value, a maximum value or a minimum value of gray levels represented by a plurality of pixel data included in the input image data IDAT. In an embodiment, in a case where the representative gray level of the input image data IDAT is between the L1-gray level and the L2-gray level, the image analyzing block 185 may determine the flicker value of the still image as the first flicker value FV1 by the flicker LUT 160, and may determine the original driving frequency before compensation as the first driving frequency DF1, for example. Further, in a case where the representative gray level of the input image data IDAT is between the L3-gray level and the L4-gray level, the image analyzing block 185 may determine the flicker value of the still image as the second flicker value FV2 by the flicker LUT 160, and may determine the original driving frequency before compensation as the second driving frequency DF2. In an embodiment, determining the flicker value and determining the original driving frequency may be performed with respect to each pixel PX or with respect to an entirety of the display panel 110. In other embodiments, determining the flicker value and determining the original driving frequency may be performed on the basis of segment.
In an embodiment, as illustrated in
The carry compensation block 190 may store the compensation value CV corresponding to the carry shift interval of the alternate driving operation, may apply the compensation value CV corresponding to the carry shift interval to the flicker value (or the original driving frequency before compensation) determined by the image analyzing block 185, and may determine the driving frequency for the display panel 110 based on the flicker value to which the compensation value CV is applied. In an embodiment, the carry compensation block 190 may calculate the flicker value to which the compensation value CV is applied by multiplying the flicker value by the compensation value CV. In an embodiment, as illustrated in
As described above, in an embodiment of the display device 100, in a case where the input image data IDAT represents the still image, the panel driver 120 may determine the flicker value of the still image, may apply the compensation value CV corresponding to the carry shift interval of the alternate driving operation to the flicker value, and may determine the driving frequency for the display panel 110 based on the flicker value to which the compensation value CV is applied. Accordingly, since compensation is performed corresponding to the carry shift interval of the alternate driving operation, in an embodiment of the display device 100, the luminance difference between the normal driving operation and the alternate driving operation may be decreased, and the flicker may be prevented.
Referring to
In a case where the input image data IDAT represents the still image (S310: YES), the panel driver 120 may determine a flicker value of the still image (S330). In an embodiment, the panel driver 120 may determine a representative gray level of the input image data IDAT representing the still image, and may determine the flicker value of the still image corresponding to the representative gray level by a flicker LUT 160 that stores a plurality of flicker values respectively corresponding to a plurality of gray levels.
The panel driver 120 may apply a compensation value CV corresponding to a carry shift interval of an alternate driving operation to the flicker value (S350). In an embodiment, the panel driver 120 may calculate the flicker value to which the compensation value CV is applied by multiplying the flicker value by the compensation value CV. Further, the panel driver 120 may determine a driving frequency for the display panel 110 based on the flicker value to which the compensation value CV is applied (S370), and may perform the alternate driving operation for the display panel 110 at the driving frequency (S390). In an embodiment, to perform the alternate driving operation, the panel driver 120 may divide a frame period into N periods, may divide a plurality of pixel rows of the display panel 110 into N pixel row groups each including the pixel rows having an interval of N pixel rows, and may sequentially drive the pixel rows included in a corresponding one of the N pixel row groups in each of the N periods, where N is an integer greater than 1.
As described above, since the driving frequency for the display panel 110 is determined by reflecting the compensation value CV to an original driving frequency before compensation determined using the flicker LUT 160, a luminance difference between the normal driving operation and the alternate driving operation may be decreased, and a flicker may be prevented.
Referring to
The controller 450 may determine a carry shift interval as 1 when input image data IDAT represents a moving image, and may determine the carry shift interval based on an original driving frequency before compensation corresponding to a flicker value of a still image when the input image data IDAT represents the still image. In an embodiment, when the input image data IDAT represents the still image, the controller 450 may determine the carry shift interval by dividing a normal driving frequency by the original driving frequency determined using a flicker LUT 460. In an embodiment, in a case where the normal driving frequency is about 60 Hz, and the original driving frequency before compensation is about 30 Hz, the controller 450 may determine the carry shift interval as 2, for example. Further, the controller 450 may determine the carry shift interval as 3 in a case where the original driving frequency before compensation is about 20 Hz, and may determine the carry shift interval as 4 in a case where the original driving frequency before compensation is about 15 Hz. Further, the controller 450 may generate a carry control signal CCS corresponding to the carry shift interval, and may provide a scan control signal SCTRL including the carry control signal CCS to the scan driver 440. In an embodiment, as illustrated in
The scan driver 440 may include a plurality of stages (e.g., . . . , STAGEM, STAGEM+1, STAGEM+2, STAGEM+3, . . . etc.) respectively providing scan signals (e.g., . . . , SSM, SSM+1, SSM+2, SSM+3, . . . etc.) to a plurality of pixel rows of the display panel 410 as illustrated in
In an embodiment, in a case where the scan driver 440 receives the first carry control signal CCS1, the plurality of first switches SW1 may sequentially connect the plurality of stages (e.g., . . . , STAGEM, STAGEM+1, STAGEM+2, STAGEM+3, . . . etc.) in response to the first carry control signal CCS1, for example. In this case, a (M)-th carry signal CRM generated by a (M)-th stage STAGEM based on a (M−1)-th carry signal CRM−1 may be shifted or transferred to a (M+1)-th stage STAGEM+1, a (M+1)-th carry signal CRM+1 generated by the (M+1)-th stage STAGEM+1 based on the (M)-th carry signal CRM may be shifted or transferred to a (M+2)-th stage STAGEM+2, a (M+2)-th carry signal CRM+2 generated by the (M+2)-th stage STAGEM+2 based on the (M+1)-th carry signal CRM+1 may be shifted or transferred to a (M+3)-th stage STAGEM+3, and a (M+3)-th carry signal CRM+3 generated by the (M+3)-th stage STAGEM+3 based on the (M+2)-th carry signal CRM+2 may be shifted or transferred to a (M+4)-th stage, where M is an integer greater than 4. Thus, the scan driver 440 may shift or transfer the carry signal CRM−4 through CRM+3 at the carry shift interval of 1 in response to the first carry control signal CCS1, and the panel driver 420 may perform a normal driving operation corresponding to the carry shift interval of 1.
Further, in a case where the scan driver 440 receives the second carry control signal CCS2, the plurality of second switches SW2 may connect the plurality of stages (e.g., . . . , STAGEM, STAGEM+1, STAGEM+2, STAGEM+3, . . . etc.) at an interval of two stages in response to the second carry control signal CCS2. Thus, even-numbered stages (e.g., . . . , STAGEM, STAGEM+2, . . . etc.) may be connected to each other, and odd-numbered stages (e.g., . . . , STAGEM+1, STAGEM+3, . . . etc.) may be connected to each other. In this case, a (M)-th carry signal CRM generated by a (M)-th stage STAGEM based on a (M−2)-th carry signal CRM−2 may be shifted or transferred to a (M+2)-th stage STAGEM+2, and a (M+2)-th carry signal CRM+2 generated by the (M+2)-th stage STAGEM+2 based on the (M)-th carry signal CRM may be shifted or transferred to a (M+4)-th stage. Further, a (M+1)-th carry signal CRM+1 generated by a (M+1)-th stage STAGEM+1 based on a (M−1)-th carry signal CRM−1 may be shifted or transferred to a (M+3)-th stage STAGEM+3, and a (M+3)-th carry signal CRM+3 generated by the (M+3)-th stage STAGEM+3 based on the (M+1)-th carry signal CRM+1 may be shifted or transferred to a (M+5)-th stage. Thus, the scan driver 440 may shift or transfer the carry signal CRM−4 through CRM+3 at the carry shift interval of 2 in response to the second carry control signal CCS2, and the panel driver 420 may perform an alternate driving operation corresponding to the carry shift interval of 2.
Further, in a case where the scan driver 440 receives the third carry control signal CCS3, the plurality of third switches SW3 may connect the plurality of stages (e.g., . . . , STAGEM, STAGEM+1, STAGEM+2, STAGEM+3, . . . etc.) at an interval of three stages in response to the third carry control signal CCS3. Thus, (3L−2)-th stages may be connected to each other, (3L−1)-th stages may be connected to each other, and (3L)-th stages may be connected to each other. In this case, a (M)-th carry signal CRM generated by a (M)-th stage STAGEM based on a (M−3)-th carry signal CRM−3 may be shifted or transferred to a (M+3)-th stage STAGEM+3, and a (M+3)-th carry signal CRM+3 generated by a (M+3)-th stage STAGEM+3 based on the (M)-th carry signal CRM may be shifted or transferred to a (M+6)-th stage. Further, a (M+1)-th carry signal CRM+1 generated by a (M+1)-th stage STAGEM+1 based on a (M−2)-th carry signal CRM−2 may be shifted or transferred to a (M+4)-th stage. Further, a (M+2)-th carry signal CRM+2 generated by a (M+2)-th stage STAGEM+2 based on a (M−1)-th carry signal CRM−1 may be shifted or transferred to a (M+5)-th stage. Thus, the scan driver 440 may shift or transfer the carry signal CRM−4 through CRM+3 at the carry shift interval of 3 in response to the third carry control signal CCS3, and the panel driver 420 may perform an alternate driving operation corresponding to the carry shift interval of 3.
Further, in a case where the scan driver 440 receives the fourth carry control signal CCS4, the plurality of fourth switches SW4 may connect the plurality of stages (e.g., . . . , STAGEM, STAGEM+1, STAGEM+2, STAGEM+3, . . . etc.) at an interval of four stages in response to the fourth carry control signal CCS4. Thus, (4K−3)-th stages may be connected to each other, (4K−2)-th stages may be connected to each other, (4K−1)-th stages may be connected to each other, and (4K)-th stages may be connected to each other, where K is an integer greater than 4. In this case, a (M)-th carry signal CRM generated by a (M)-th stage STAGEM based on a (M−4)-th carry signal CRM−4 may be shifted or transferred to a (M+4)-th stage. Further, a (M+1)-th carry signal CRM+1 generated by a (M+1)-th stage STAGEM+1 based on a (M−3)-th carry signal CRM−3 may be shifted or transferred to a (M+5)-th stage. Further, a (M+2)-th carry signal CRM+2 generated by a (M+2)-th stage STAGEM+2 based on a (M−2)-th carry signal CRM−2 may be shifted or transferred to a (M+6)-th stage. Further, a (M+3)-th carry signal CRM+3 generated by a (M+3)-th stage STAGEM+3 based on a (M−1)-th carry signal CRM−1 may be shifted or transferred to a (M+7)-th stage. Thus, the scan driver 440 may shift or transfer the carry signal CRM−4 through CRM+3 at the carry shift interval of 4 in response to the fourth carry control signal CCS4, and the panel driver 420 may perform an alternate driving operation corresponding to the carry shift interval of 4.
The controller 450 may determine whether the input image data IDAT represents the still image. When the input image data IDAT represents the still image, the controller 450 may determine a flicker value of the still image, may read a compensation value CV corresponding to the carry shift interval of the alternate driving operation from the carry compensation value table 495, may apply the compensation value CV corresponding to the carry shift interval to the flicker value, may determine a driving frequency for the display panel 410 based on the flicker value to which the compensation value CV is applied, and may perform the alternate driving operation for the display panel 410 based on the driving frequency. In an embodiment, to perform these operations, as illustrated in
The driving frequency decider 480 may include a flicker LUT 460 that stores a plurality of flicker values respectively corresponding to a plurality of gray levels, an image analyzing block 485 that determines a representative gray level of the input image data IDAT representing the still image, and determines the flicker value of the still image corresponding to the representative gray level by the flicker LUT 460, a carry compensation value table 495 and a carry compensation block 490.
The carry compensation value table 495 may store a plurality of compensation values CV respectively corresponding to a plurality of carry shift intervals CPI. In an embodiment, the panel driver 420 may perform the normal driving operation at a carry shift interval CPI of 1 or the alternate driving operation at a carry shift interval CPI of 2, a carry shift interval CPI of 3 or a carry shift interval CPI of 4. In this case, the carry compensation value table 495 may store, but not limited to, a compensation value CV of α1 corresponding to the carry shift interval CPI of 2, a compensation value CV of α2 corresponding to the carry shift interval CPI of 3, and a compensation value CV of α3 corresponding to the carry shift interval CPI of 4, for example.
The carry compensation block 490 may read the compensation value CV corresponding to a current carry shift interval from the carry compensation value table 495. In an embodiment, the carry compensation block 490 may read the compensation value CV of α1 when the alternate driving operation is performed at the carry shift interval CPI of 2, may read the compensation value CV of α2 when the alternate driving operation is performed at the carry shift interval CPI of 3, and may read the compensation value CV of α3 when the alternate driving operation is performed at the carry shift interval CPI of 4, for example. The carry compensation block 490 may apply the compensation value CV corresponding to the current carry shift interval to the flicker value, and may determine the driving frequency for the display panel 410 based on the flicker value to which the compensation value CV is applied. In an embodiment, the carry compensation block 490 may determine the driving frequency by multiplying the flicker value by the compensation value CV of α1 when the alternate driving operation is performed at the carry shift interval CPI of 2, may determine the driving frequency by multiplying the flicker value by the compensation value CV of α2 when the alternate driving operation is performed at the carry shift interval CPI of 3, and may determine the driving frequency by multiplying the flicker value by the compensation value CV of α3 when the alternate driving operation is performed at the carry shift interval CPI of 4, for example. When the display panel 410 is driven at the driving frequency determined based on the flicker value to which the compensation value CV corresponding to the current carry shift interval is applied, a flicker may be prevented.
As described above, in an embodiment of the display device 400, in a case where the input image data IDAT represents the still image, the panel driver 420 may determine the flicker value of the still image, may read the compensation value CV corresponding to the current carry shift interval from the carry compensation value table 495, may apply the compensation value CV corresponding to the current carry shift interval to the flicker value, may determine the driving frequency for the display panel 410 based on the flicker value to which the compensation value CV is applied, and may perform the alternate driving operation for the display panel 410 at the driving frequency. Accordingly, since compensation is performed corresponding to the current carry shift interval, in an embodiment of the display device 400, a luminance difference between the normal driving operation and the alternate driving operation may be decreased, and the flicker may be prevented.
Referring to
The controller 550 may include the plurality of flicker LUTs 561, . . . , 562 respectively corresponding to the plurality of carry shift intervals. In an embodiment, each of the plurality of flicker LUTs 561, . . . , 562 may store a plurality of flicker values respectively corresponding to a plurality of gray levels with respect to a corresponding one of the plurality of carry shift intervals. In an embodiment, a first flicker LUT 561 may store a plurality of flicker values obtained by tests or experiments with respect to the display device 500 performing a normal driving operation at a carry shift interval of 1, and a (N)-th flicker LUT 562 may store a plurality of flicker values obtained by tests or experiments with respect to the display device 500 performing an alternate driving operation at a carry shift interval of N, where N is an integer greater than 1, for example.
The controller 550 may determine whether input image data IDAT represents a still image. When the input image data IDAT represents the still image, the controller 550 may select a flicker LUT (e.g., 562) corresponding to a current carry shift interval from among the plurality of flicker LUTs 561, . . . , 562, may determine a flicker value of the still image by the selected flicker LUT (e.g., 562), may determine a driving frequency for the display panel 510 based on the flicker value, and may perform the alternate driving operation for the display panel 510 at the driving frequency. Since the plurality of flicker values stored in the selected flicker LUT (e.g., 562) are obtained by the tests or experiments with respect to the display device 500 performing the alternate driving operation at the current carry shift interval, the flicker value determined using the selected flicker LUT (e.g., 562) may compensate a luminance difference by the alternate driving operation. Thus, the luminance difference at the alternate driving operation may be decreased, and a flicker may be prevented.
In an embodiment, the controller 550 may further include a still image detector 570 and a driving frequency decider 580. The still image detector 570 may determine whether the input image data IDAT represents the still image. When the input image data IDAT does not represent the still image, the driving frequency decider 580 may determine the driving frequency for the display panel 510 as a normal driving frequency. When the input image data IDAT represents the still image, the driving frequency decider 580 may determine a representative gray level of the input image data IDAT representing the still image, may select the flicker LUT corresponding to the current carry shift interval from among the plurality of flicker LUTs 561, . . . , 562, may determine the flicker value of the still image corresponding to the representative gray level by the selected flicker LUT, and may determine the driving frequency for the display panel 510 based on the flicker value.
As described above, in an embodiment of the display device 500, in a case where the input image data IDAT represents the still image, the panel driver 520 may determine the driving frequency for the display panel 510 by the plurality of flicker LUTs 561, . . . , 562 respectively corresponding to the plurality of carry shift intervals, and may perform the alternate driving operation for the display panel 510 at the driving frequency. Accordingly, since the flicker LUT corresponding to the current carry shift interval of the alternate driving operation is used, a luminance difference between the normal driving operation and the alternate driving operation may be decreased, and the flicker may be prevented.
Referring to
The processor 1110 may perform various computing functions or tasks. In an embodiment, the processor 1110 may be an application processor (“AP”), a microprocessor, a central processing unit (“CPU”), etc. In an embodiment, the processor 1110 may be coupled to other components via an address bus, a control bus, a data bus, etc. Further, in an embodiment, the processor 1110 may be further coupled to an extended bus such as a peripheral component interconnection (“PCI”) bus.
The memory device 1120 may store data for operations of the electronic device 1100. In an embodiment, the memory device 1120 may include at least one non-volatile memory device such as an erasable programmable read-only memory (“EPROM”) device, an electrically erasable programmable read-only memory (“EEPROM”) device, a flash memory device, a phase change random access memory (“PRAM”) device, a resistance random access memory (“RRAM”) device, a nano floating gate memory (“NFGM”) device, a polymer random access memory (“PoRAM”) device, a magnetic random access memory (“MRAM”) device, a ferroelectric random access memory (“FRAM”) device, etc., and/or at least one volatile memory device such as a dynamic random access memory (“DRAM”) device, a static random access memory (“SRAM”) device, a mobile dynamic random access memory (“mobile DRAM”) device, etc., for example.
In an embodiment, the storage device 1130 may be a solid state drive (“SSD”) device, a hard disk drive (“HDD”) device, a compact disc read-only memory (“CD-ROM”) device, etc. In an embodiment, the I/O device 1140 may be an input device such as a keyboard, a keypad, a mouse, a touch screen, etc., and an output device such as a printer, a speaker, etc. The power supply 1150 may supply power for operations of the electronic device 1100. The display device 1160 may be coupled to other components through the buses or other communication links.
In the display device 1160, in a case where input image data represents a still image, a flicker value of the still image may be determined, a compensation value corresponding to a carry shift interval may be applied to the flicker value, a driving frequency for a display panel may be determined based on the flicker value to which the compensation value is applied, and an alternate driving operation for the display panel may be performed at the driving frequency. Accordingly, since compensation is performed corresponding to the carry shift interval of the alternate driving operation, a luminance difference between a normal driving operation and the alternate driving operation may be decreased, and a flicker may be prevented.
Embodiments of the inventions may be applied to any display device 1160, and any electronic device 1100 including the display device 1160. The embodiments may be applied to a mobile phone, a smart phone, a wearable electronic device, a tablet computer, a television (“TV”), a digital TV, a three-dimensional (“3D”) TV, a personal computer (“PC”), a home appliance, a laptop computer, a personal digital assistant (“PDA”), a portable multimedia player (“PMP”), a digital camera, a music player, a portable game console, a navigation device, etc., for example.
The foregoing is illustrative of embodiments and is not to be construed as limiting thereof. Although a few embodiments have been described, those skilled in the art will readily appreciate that many modifications are possible in the embodiments without materially departing from the novel teachings and advantages of the invention. Accordingly, all such modifications are intended to be included within the scope of the invention as defined in the claims. Therefore, it is to be understood that the foregoing is illustrative of various embodiments and is not to be construed as limited to the embodiments disclosed, and that modifications to the disclosed embodiments, as well as other embodiments, are intended to be included within the scope of the appended claims.
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