Patent Grant
11289034
This application claims priority under 35 USC § 119 to Korean Patent Application No. 10-2019-0092272, filed on Jul. 30, 2019 in the Korean Intellectual Property Office (KIPO), the disclosure of the Korean Patent Application is incorporated herein in its entirety by reference.
Embodiments of the present inventive concept relate to display devices, and more particularly to display devices performing local dimming.
In a display device, such as a liquid crystal display (LCD) device, luminance of the display device is determined by a product of luminance of a backlight unit and light transmittance of liquid crystals depending on image data. The LCD device may employ a backlight dimming method for the purpose of increasing a contrast ratio and reducing power consumption. The backlight dimming method controls backlight luminance and compensates image data by analyzing an input image and adjusting a dimming value based on the analysis. For example, to reduce power consumption, the backlight dimming method may reduce the backlight luminance by decreasing a dimming value (or a duty), and may increase the luminance through data compensation. Thus, power consumption of the backlight unit may be reduced.
A light emitting diode (LED) backlight unit using LEDs as a light source has been used for the backlight unit. The LEDs may boast of high luminance and low power consumption, compared with conventional lamps. Because the LEDs of the LED backlight unit allow for location-based control, the LEDs may be driven by local dimming According to the local dimming technology, the LED backlight unit may be divided into light source blocks and luminance may be controlled on a block-by-block basis. Further, in the local dimming method, local dimming values (or duties) may be determined by analyzing image data on a block basis, and the image data may be compensated based on the local dimming values. Accordingly, the contrast ratio may be increased, and the power consumption may be decreased.
In a conventional display device, to reduce after images or motion blurring, light source rows of the backlight unit are sequentially driven on a row-by-row basis when the local dimming is performed. However, a waterfall phenomenon where a horizontal line image having relatively high or low luminance exists or gradually moves may be caused by the sequential driving of the light source rows.
Some example embodiments provide a display device capable of preventing or reducing a waterfall phenomenon when local dimming is performed.
According to example embodiments, there is provided a display device including a backlight unit including a plurality of light source rows, each of the plurality of light source rows including a plurality of light source blocks, a display panel configured to display an image by transmitting light emitted by the backlight unit, a panel driver configured to drive the display panel, and a backlight driver configured to drive the backlight unit. The backlight driver performs a vertical direction scan operation that sequentially selects the plurality of light source rows and a horizontal direction sequential driving operation that sequentially drives the plurality of light source blocks included in a selected one of the plurality of light source rows.
In example embodiments, to perform the vertical direction scan operation, the backlight driver may sequentially select one of the plurality of light source rows per first time.
In example embodiments, the first time may be determined by dividing a frame time by a number of the plurality of light source rows.
In example embodiments, to perform the horizontal direction sequential driving operation, the backlight driver may sequentially drive one of the plurality of light source blocks included in the selected one of the plurality of light source rows per second time.
In example embodiments, the second time may be determined by dividing a latency time from a data input time point to an image display time point by a number of the plurality of light source blocks included in each of the plurality of light source rows.
In example embodiments, the plurality of light source rows may include a first light source row and a second light source row, and the backlight driver may initiate the horizontal direction sequential driving operation for the second light source row before the horizontal direction sequential driving operation for the first light source row is completed.
In example embodiments, each of the plurality of light source rows may include first through M-th light source blocks, where M is an integer greater than 1. To perform the horizontal direction sequential driving operation, the backlight driver may sequentially drive the first through M-th light source blocks included in the selected one of the plurality of light source rows in a first horizontal direction from the first light source block to the M-th light source block in an odd-numbered frame, and may sequentially drive the first through M-th light source blocks included in the selected one of the plurality of light source rows in a second horizontal direction from the M-th light source block to the first light source block in an even-numbered frame.
According to example embodiments, there is provided a display device including a backlight unit including a plurality of light source rows, each of the plurality of light source rows including a plurality of light source blocks, a display panel configured to display an image by transmitting light emitted by the backlight unit, a panel driver configured to drive the display panel, and a backlight driver configured to drive the backlight unit. The backlight driver divides the backlight unit into a plurality of horizontal regions, and performs, in each of the plurality of horizontal regions, a vertical direction scan operation that sequentially selects the plurality of light source rows and a horizontal direction sequential driving operation that sequentially drives the plurality of light source blocks included in a selected one of the plurality of light source rows.
In example embodiments, to perform the horizontal direction sequential driving operation in each of the plurality of horizontal regions, the backlight driver may sequentially drive one of the plurality of light source blocks included in the selected one of the plurality of light source rows in each of the plurality of horizontal regions per a block shift time.
In example embodiments, the block shift time may be determined by dividing a latency time from a data input time point to an image display time point by a number of the plurality of light source blocks included in each of the plurality of light source rows in each of the plurality of horizontal regions.
In example embodiments, to perform the horizontal direction sequential driving operation in each of the plurality of horizontal regions, the backlight driver may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows in each of the plurality of horizontal regions in a first horizontal direction in an odd-numbered frame, and may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows in each of the plurality of horizontal regions in a second horizontal direction opposite to the first horizontal direction in an even-numbered frame.
In example embodiments, the backlight driver may group the plurality of light source rows into an odd-numbered light source row group and an even-numbered light source row group. To perform the horizontal direction sequential driving operation in each of the plurality of horizontal regions, the backlight driver may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows belonging to the odd-numbered light source row group in each of the plurality of horizontal regions in a first horizontal direction, and may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows belonging to the even-numbered light source row group in each of the plurality of horizontal regions in a second horizontal direction opposite to the first horizontal direction.
In example embodiments, the backlight driver may group the plurality of light source rows into an odd-numbered light source row group and an even-numbered light source row group. To perform the horizontal direction sequential driving operation in each of the plurality of horizontal regions in an odd-numbered frame, the backlight driver may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows belonging to the odd-numbered light source row group in each of the plurality of horizontal regions in a first horizontal direction, and may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows belonging to the even-numbered light source row group in each of the plurality of horizontal regions in a second horizontal direction opposite to the first horizontal direction. To perform the horizontal direction sequential driving operation in each of the plurality of horizontal regions in an even-numbered frame, the backlight driver may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows belonging to the odd-numbered light source row group in each of the plurality of horizontal regions in the second horizontal direction, and may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows belonging to the even-numbered light source row group in each of the plurality of horizontal regions in the first horizontal direction.
In example embodiments, the backlight driver may group (4K+1)-th and (4K+2)-th ones of the plurality of light source rows into a first light source row group, and may group (4K+3)-th and (4K+4)-th ones of the plurality of light source rows into a second light source row group, where K is an integer greater than 0. To perform the horizontal direction sequential driving operation in each of the plurality of horizontal regions, the backlight driver may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows belonging to the first light source row group in each of the plurality of horizontal regions in a first horizontal direction, and may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows belonging to the second light source row group in each of the plurality of horizontal regions in a second horizontal direction opposite to the first horizontal direction.
In example embodiments, the backlight driver may group (4K+1)-th and (4K+2)-th ones of the plurality of light source rows into a first light source row group, and may group (4K+3)-th and (4K+4)-th ones of the plurality of light source rows into a second light source row group, where K is an integer greater than 0. To perform the horizontal direction sequential driving operation in each of the plurality of horizontal regions in an odd-numbered frame, the backlight driver may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows belonging to the first light source row group in each of the plurality of horizontal regions in a first horizontal direction, and may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows belonging to the second light source row group in each of the plurality of horizontal regions in a second horizontal direction opposite to the first horizontal direction. To perform the horizontal direction sequential driving operation in each of the plurality of horizontal regions in an even-numbered frame, the backlight driver may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows belonging to the first light source row group in each of the plurality of horizontal regions in the second horizontal direction, and may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows belonging to the second light source row group in each of the plurality of horizontal regions in the first horizontal direction.
In example embodiments, to perform the horizontal direction sequential driving operation in an odd-numbered horizontal region of the plurality of horizontal regions, the backlight driver may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows in the odd-numbered horizontal region in a first horizontal direction. To perform the horizontal direction sequential driving operation in an even-numbered horizontal region of the plurality of horizontal regions, the backlight driver may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows in the even-numbered horizontal region in a second horizontal direction opposite to the first horizontal direction.
In example embodiments, the horizontal direction sequential driving operation in the odd-numbered horizontal region and the horizontal direction sequential driving operation in the even-numbered horizontal region may have different start time points.
In example embodiments, the horizontal direction sequential driving operation in the odd-numbered horizontal region and the horizontal direction sequential driving operation in the even-numbered horizontal region may have different block shift times.
In example embodiments, to perform the horizontal direction sequential driving operation in an odd-numbered horizontal region of the plurality of horizontal regions, the backlight driver may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows in the odd-numbered horizontal region in a first horizontal direction in an odd-numbered frame, and may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows in the odd-numbered horizontal region in a second horizontal direction opposite to the first horizontal direction in an even-numbered frame. To perform the horizontal direction sequential driving operation in an even-numbered horizontal region of the plurality of horizontal regions, the backlight driver may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows in the even-numbered horizontal region in the second horizontal direction in the odd-numbered frame, and may sequentially drive the plurality of light source blocks in the selected one of the plurality of light source rows in the even-numbered horizontal region in the first horizontal direction in the even-numbered frame.
In example embodiments, the horizontal direction sequential driving operation in the odd-numbered horizontal region and the horizontal direction sequential driving operation in the even-numbered horizontal region may have different start time points or different block shift times.
An embodiment may be related to a display device. The display device includes a backlight unit including light source rows, each of the light source rows including light source blocks; a display panel configured to display an image by transmitting light emitted by the backlight unit; a panel driver configured to drive the display panel; and a backlight driver configured to drive the backlight unit. The backlight driver is configured to perform a vertical direction scan operation that sequentially selects the light source rows and a horizontal direction sequential driving operation that sequentially drives the light source blocks included in a selected light source row of the light source rows.
To perform the vertical direction scan operation, the backlight driver is configured to sequentially select a light source row of the light source rows based on a first time period.
The first time period is determined by dividing a frame time by a number of the light source rows.
To perform the horizontal direction sequential driving operation, the backlight driver is configured to sequentially drive a light source block of the light source blocks included in the selected light source row of the light source rows based on a second time period.
The second time period is determined by dividing a latency time from a data input time point to an image display time point by a number of the light source blocks included in each of the light source rows.
The light source rows include a first light source row and a second light source row, and the backlight driver is configured to initiate the horizontal direction sequential driving operation for the second light source row before the horizontal direction sequential driving operation for the first light source row is completed.
Each of the light source rows includes first through M-th light source blocks, where M is an integer greater than 1. To perform the horizontal direction sequential driving operation, the backlight driver is configured to sequentially drive the first through M-th light source blocks included in the selected light source row of the light source rows in a first horizontal direction from the first light source block to the M-th light source block in an odd-numbered frame, and sequentially drive the first through M-th light source blocks included in the selected light source row of the light source rows in a second horizontal direction from the M-th light source block to the first light source block in an even-numbered frame.
In an embodiment, the display device includes a backlight unit including light source rows, each of the light source rows including light source blocks; a display panel configured to display an image by transmitting light emitted by the backlight unit; a panel driver configured to drive the display panel; and a backlight driver configured to drive the backlight unit. The backlight driver is configured to divide the backlight unit into horizontal regions, and perform, in each of the horizontal regions, a vertical direction scan operation that sequentially selects the light source rows and a horizontal direction sequential driving operation that sequentially drives the light source blocks included in a selected light source row of the light source rows.
To perform the horizontal direction sequential driving operation in each of the horizontal regions, the backlight driver is configured to sequentially drive a light source block of the light source blocks included in the selected light source row of the light source rows in each of the horizontal regions per a block shift time.
The block shift time is determined by dividing a latency time from a data input time point to an image display time point by a number of the light source blocks included in each of the light source rows in each of the horizontal regions.
To perform the horizontal direction sequential driving operation in each of the horizontal regions, the backlight driver is configured to sequentially drive the light source blocks in the selected light source row of the light source rows in each of the horizontal regions in a first horizontal direction in an odd-numbered frame, and sequentially drive the light source blocks in the selected light source row of the light source rows in each of the horizontal regions in a second horizontal direction opposite to the first horizontal direction in an even-numbered frame.
The backlight driver is configured to group the light source rows into an odd-numbered light source row group and an even-numbered light source row group. To perform the horizontal direction sequential driving operation in each of the horizontal regions, the backlight driver is configured to sequentially drive the light source blocks in the selected light source row of the light source rows belonging to the odd-numbered light source row group in each of the horizontal regions in a first horizontal direction, and sequentially drive the light source blocks in the selected light source row of the light source rows belonging to the even-numbered light source row group in each of the horizontal regions in a second horizontal direction opposite to the first horizontal direction.
The backlight driver is configured to group the light source rows into an odd-numbered light source row group and an even-numbered light source row group. To perform the horizontal direction sequential driving operation in each of the horizontal regions in an odd-numbered frame, the backlight driver is configured to sequentially drive the light source blocks in the selected light source row of the light source rows belonging to the odd-numbered light source row group in each of the horizontal regions in a first horizontal direction, and sequentially drive the light source blocks in the selected light source row of the light source rows belonging to the even-numbered light source row group in each of the horizontal regions in a second horizontal direction opposite to the first horizontal direction. To perform the horizontal direction sequential driving operation in each of the horizontal regions in an even-numbered frame, the backlight driver is configured to sequentially drive the light source blocks in the selected light source row of the light source rows belonging to the odd-numbered light source row group in each of the horizontal regions in the second horizontal direction, and sequentially drive the light source blocks in the selected light source row of the light source rows belonging to the even-numbered light source row group in each of the horizontal regions in the first horizontal direction.
The backlight driver is configured to group (4K+1)-th and (4K+2)-th light source rows of the light source rows into a first light source row group, and group (4K+3)-th and (4K+4)-th light source rows of the light source rows into a second light source row group, where K is an integer greater than 0. To perform the horizontal direction sequential driving operation in each of the horizontal regions, the backlight driver is configured to sequentially drive the light source blocks in the selected light source row of the light source rows belonging to the first light source row group in each of the horizontal regions in a first horizontal direction, and sequentially drive the light source blocks in the selected light source row of the light source rows belonging to the second light source row group in each of the horizontal regions in a second horizontal direction opposite to the first horizontal direction.
The backlight driver is configured to group (4K+1)-th and (4K+2)-th light source rows of the light source rows into a first light source row group, and group (4K+3)-th and (4K+4)-th light source rows of the light source rows into a second light source row group, where K is an integer greater than 0. To perform the horizontal direction sequential driving operation in each of the horizontal regions in an odd-numbered frame, the backlight driver is configured to sequentially drive the light source blocks in the selected light source row of the light source rows belonging to the first light source row group in each of the horizontal regions in a first horizontal direction, and sequentially drive the light source blocks in the selected light source row of the light source rows belonging to the second light source row group in each of the horizontal regions in a second horizontal direction opposite to the first horizontal direction. To perform the horizontal direction sequential driving operation in each of the horizontal regions in an even-numbered frame, the backlight driver is configured to sequentially drive the light source blocks in the selected light source row of the light source rows belonging to the first light source row group in each of the horizontal regions in the second horizontal direction, and sequentially drive the light source blocks in the selected light source row of the light source rows belonging to the second light source row group in each of the horizontal regions in the first horizontal direction.
To perform the horizontal direction sequential driving operation in an odd-numbered horizontal region of the horizontal regions, the backlight driver is configured to sequentially drive the light source blocks in the selected light source row of the light source rows in the odd-numbered horizontal region in a first horizontal direction. To perform the horizontal direction sequential driving operation in an even-numbered horizontal region of the horizontal regions, the backlight driver is configured to sequentially drive the light source blocks in the selected light source row of the light source rows in the even-numbered horizontal region in a second horizontal direction opposite to the first horizontal direction.
The horizontal direction sequential driving operation in the odd-numbered horizontal region and the horizontal direction sequential driving operation in the even-numbered horizontal region have different start time points.
The horizontal direction sequential driving operation in the odd-numbered horizontal region and the horizontal direction sequential driving operation in the even-numbered horizontal region have different block shift times.
To perform the horizontal direction sequential driving operation in an odd-numbered horizontal region of the horizontal regions, the backlight driver is configured to sequentially drive the light source blocks in the selected light source row of the light source rows in the odd-numbered horizontal region in a first horizontal direction in an odd-numbered frame, and sequentially drive the light source blocks in the selected light source row of the light source rows in the odd-numbered horizontal region in a second horizontal direction opposite to the first horizontal direction in an even-numbered frame. To perform the horizontal direction sequential driving operation in an even-numbered horizontal region of the horizontal regions, the backlight driver is configured to sequentially drive the light source blocks in the selected light source row of the light source rows in the even-numbered horizontal region in the second horizontal direction in the odd-numbered frame, and sequentially drive the light source blocks in the selected light source row of the light source rows in the even-numbered horizontal region in the first horizontal direction in the even-numbered frame.
The horizontal direction sequential driving operation in the odd-numbered horizontal region and the horizontal direction sequential driving operation in the even-numbered horizontal region have different start time points or different block shift times.
As described above, a display device according to example embodiments may perform a vertical direction scan operation that sequentially selects light source rows included in a backlight unit, and a horizontal direction sequential driving operation that sequentially drives light source blocks included in a selected one of the light source rows. Accordingly, while local dimming is performed, a waterfall phenomenon where a relatively high or low luminance horizontal line image exists or gradually moves may be prevented or reduced.
Illustrative, non-limiting example embodiments will be more clearly understood from the following detailed description in conjunction with the accompanying drawings.
Hereinafter, embodiments of the present inventive concept will be explained in detail with reference to the accompanying drawings.
Referring to
The display panel 110 may include data lines, gate lines, and pixels PX coupled to the data lines and the gate lines. The display panel 110 may selectively transmit light emitted by the backlight unit 160 to display an image. In some example embodiments, each pixel PX may include a switching transistor and a liquid crystal capacitor coupled to the switching transistor, and the display panel 110 may be a liquid crystal display (LCD) panel. However, the display panel 110 according to example embodiments may be any suitable display panel. The display panel 110 may include pixel blocks respectively corresponding to light source blocks of the backlight unit 160. Here, a set of the pixels PX located corresponding to one light source block may be referred to as the pixel block. Thus, here, the pixel block may be a logical unit of the pixels PX that are grouped according to the light source block, and the pixel blocks may not be physically or structurally distinguished from each other.
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 pixels PX through the data lines. For example, the data control signal DCTRL may include an output data enable signal, a horizontal start signal and a load signal. In an example embodiment, the data driver 130 may be implemented with one or more data integrated circuits (ICs). Further, according to an example embodiment, the data driver 130 may be mounted directly on the display panel 110 in a form of a chip on glass (COG), or may be coupled to the display panel 110 in a form of a chip on film (COF) or a tape carrier package (TCP). In an example embodiment, the data driver 130 may be integrated in a peripheral portion of the display panel 110.
The gate driver 140 may generate the gate signals GS based on a gate control signal GCTRL received from the controller 150, and may provide the gate signals GS to the pixels PX through the gate lines. For example, the gate control signal GCTRL may include a vertical start signal STV and a gate clock signal. In some example embodiments, the gate driver 140 may be implemented as an amorphous silicon gate (ASG) driver integrated in the peripheral portion of the display panel 110. In other example embodiments, the gate driver 140 may be implemented with one or more gate ICs. Further, according to some example embodiments, the gate driver 140 may be mounted directly on the display panel 110 in the form of COG, or may be coupled to the display panel 110 in the form of COF or TCP.
The controller 150, e.g., a timing controller, may receive input image data IDAT and a control signal CTRL from an external host, e.g., a graphic processing unit (GPU) or a graphic card. For example, the input image data IDAT may be RGB image data including red image data, green image data and blue image data. Further, for example, the control signal CTRL may include a master clock signal, a data enable signal, a vertical synchronization signal, a horizontal synchronization signal, etc. The controller 150 may generate the output image data ODAT, the data control signal DCTRL, the gate control signal GCTRL and a backlight control signal BCTRL based on the input image data IDAT and the control signal CTRL. In some example embodiments, the controller 150 may generate the output image data ODAT by performing an image enhancement operation, a luminance non-uniformity correction operation, a dynamic capacitance compensation (DCC) operation, etc. on the input image data IDAT. 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, may control an operation of the gate driver 140 by providing the gate control signal GCTRL to the gate driver 140, and may control an operation of the backlight driver 170 by providing the backlight control signal BCTRL to the backlight driver 170.
The backlight unit 160 may include light source rows, and each light source row may include light source blocks. For example, as illustrated in
The backlight driver 170 may drive the backlight unit 160 based on the backlight control signal BCTRL received from the controller 150. In an example embodiment, the backlight control signal BCTRL may include a dimming signal SDIM representing that local dimming is to be performed, and the backlight driver 170 may perform the local dimming in response to the dimming signal SDIM. In some example embodiments, the dimming signal SDIM may further represent duties of light source block driving signals, e.g., pulse width modulation (PWM) signals, that are to be respectively applied to the N*M light source blocks B11, B12, . . . , B1M, B21, B22, . . . , B2M, . . . , BN1, BN2, . . . , BNM included in the backlight unit 160. For example, the controller 150 may determine the duties of the light source block driving signals by analyzing the input image data IDAT for the pixel blocks of the display panel 110 respectively corresponding to the N*M light source blocks B11, B12, . . . , B1M, B21, B22, . . . , B2M, . . . , BN1, BN2, . . . , BNM, and may provide the dimming signal SDIM representing the determined duties to the backlight driver 170. In an example, the controller 150 may determine the duty of the light source block driving signal for each light source block according to a representative gray value (e.g., a maximum gray value and/or an average gray value) of the pixel block corresponding to each light source block. The backlight driver 170 may perform the local dimming by driving the N*M light source blocks B11, B12, . . . , B1M, B21, B22, . . . , B2M, . . . , BN1, BN2, . . . , BNM with the determined duties represented by the dimming signal SDIM, or by driving the N*M light source blocks B11, B12, . . . , B1M, B21, B22, . . . , B2M, . . . , BN1, BN2, . . . , BNM for durations corresponding to the determined duties.
To perform the local dimming, the backlight driver 170 may sequentially drive the N*M light source blocks B11, B12, . . . , B1M, B21, B22, . . . , B2M, . . . , BN1, BN2, . . . , BNM not only in a vertical direction, e.g., in a direction of each data line, but also in a horizontal direction, e.g., in a direction of each gate line. Thus, driving start time points of the N*M light source blocks B11, B12, . . . , B1M, B21, B22, . . . , B2M, . . . , BN1, BN2, . . . , BNM may be determined sequentially in the vertical direction and the horizontal direction, and driving durations, i.e., the time period or length of time of driving, of the N*M light source blocks B11, B12, . . . , B1M, B21, B22, . . . , B2M, . . . , BN1, BN2, . . . , BNM may be determined by the determined duties represented by the dimming signal SDIM. In an example embodiment, to sequentially drive the N*M light source blocks B11, B12, . . . , B1M, B21, B22, . . . , B2M, . . . , BN1, BN2, . . . , BNM in the vertical direction and in the horizontal direction, the backlight driver 170 performs a vertical direction scan operation that sequentially select the light source rows LSR1, LSR2, . . . , LSRN and a horizontal direction sequential driving operation that sequentially drives the light source blocks, e.g., B11, B12, . . . , B1M, included in each selected light source row, e.g., light source row LSR1.
In a conventional display device, light source rows of a backlight unit may be sequentially driven to perform the local dimming, and light source blocks in each light source row may be substantially simultaneously driven. Since the light source blocks in each light source row are substantially simultaneously driven, luminance of each light source block may be affected by luminances of adjacent light source blocks. In particular, when the local dimming is performed in the conventional display device, a waterfall phenomenon where a relatively high or low luminance horizontal line image exists or gradually moves may be caused by the sequential driving of the light source rows. However, in the display device 100 according to an example embodiment, the light source blocks B11, B12, . . . , B1M, B21, B22, . . . , B2M, . . . , BN1, BN2, . . . , BNM of the backlight unit 160 are sequentially driven in the vertical direction and the horizontal direction by the vertical direction scan operation and the horizontal direction sequential driving operation. Accordingly, the influence of the luminance of the adjacent light source blocks on the luminance of each light source block may be reduced, and the waterfall phenomenon may be prevented or reduced while the local dimming is performed.
Referring to
The backlight driver 170 may perform a vertical direction scan operation and a horizontal direction sequential driving operation for the backlight unit 160 in response to the dimming signal SDIM in an operation S250. The vertical direction scan operation may be an operation that sequentially selects light source rows included in the backlight unit 160 in a vertical direction, e.g., a direction of each data line, and the horizontal direction sequential driving operation may be an operation that sequentially drives light source blocks included in each light source row in a horizontal direction, e.g., a direction of each gate line.
For example, as illustrated in driving timing 310 of
To perform the vertical direction scan operation V-SCAN, the backlight driver 170 may sequentially select one of the light source rows LSR1, LSR2, LSR3, . . . per first time T1, e.g., based on a first time period. The first time T1 is a first time period, or a length of time, from a time point. A time point is a specific point in time, e.g., a specific point in time when a light source row is selected. For example, the backlight driver 170 may select the second light source row LSR2 after the first time T1 from a time point at which a first light source row LSR1 is selected, and may select the third light source row LSR3 after the first time T1 from a time point at which the second light source row LSR2 is selected. In some example embodiments, the first time T1 may be determined by dividing a frame time FT by the number of the light source rows LSR1, LSR2, LSR3, . . . . The frame time FT is a time period, or length of time, of a frame. For example, in a case where the display device 100 operates at a frame rate of about 120 Hz, and the backlight unit 160 includes 16 light source rows LSR1, LSR2, LSR3, . . . , the frame time FT may be about 8.3 ms (= 1/120 ms), and the first time T1 may be about 0.52 ms (=8.3/16 ms).
Further, to perform the horizontal direction sequential driving operation H-SD, the backlight driver 170 may sequentially drive one of the light source blocks, e.g., light source blocks B11, B12, B13, . . . , B1M, included in the selected light source row, e.g., light source row LSR1, per second time T2. The second time T2 is a second time period, or a length of time, from a time point. For example, when the first light source row LSR1 is selected, the light source blocks B11, B12, B13, . . . , B1M of the first light source row LSR1 may be sequentially driven per the second time T2. Further, when the second light source row LSR2 is selected after the first time T1 from the time point at which the first light source row LSR1 is selected, the light source blocks B21, B22, B23, . . . , B2M of the second light source row LSR2 may be sequentially driven per the second time T2. In some example embodiments, as illustrated in
In the display device that performs only the vertical direction scan operation V-SCAN and the display device 100 that performs the vertical direction scan operation V-SCAN and the horizontal direction sequential driving operation H-SD, the backlight unit 160 may operate as illustrated in
However, in the display device 100 that operates according to the driving timing 320, light emission of a first light source block B11 of the first light source row LSR1 may be initiated. Light emission of a second light source block B12 of the first light source row LSR1 may be initiated after the second time T2. Light emission of a third light source block B13 of the first light source row LSR1 may be initiated after the second time T2. Light emission of a fourth light source block B14 of the first light source row LSR1 may be initiated after the second time T2.
Then, light emission of a first light source block B21 of the second light source row LSR2 and a fifth light source block B15 of the first light source row LSR1 may be initiated. Light emission of a second light source block B22 of the second light source row LSR2 and a sixth light source block B16 of the first light source row LSR1 may be initiated after the second time T2. Light emission of a third light source block B23 of the second light source row LSR2 and a seventh light source block B17 of the first light source row LSR1 may be initiated after the second time T2. Light emission of a fourth light source block B24 of the second light source row LSR2 and an eighth light source block B18 of the first light source row LSR1 may be initiated after the second time T2.
Then, light emission of a first light source block B31 of the third light source row LSR3, a fifth light source block B25 of the second light source row LSR2 and a ninth light source block B19 of the first light source row LSR1 may be initiated. Light emission of a second light source block B32 of the third light source row LSR3 and a sixth light source block B26 of the second light source row LSR2 may be initiated after the second time T2. Light emission of a third light source block B33 of the third light source row LSR3 and a seventh light source block B27 of the second light source row LSR2 may be initiated after the second time T2. Light emission of a fourth light source block B34 of the third light source row LSR3 and an eighth light source block B28 of the second light source row LSR2 may be initiated after the second time T2.
An operation of the display device that performs only the vertical direction scan operation V-SCAN and the display device 100 that performs the vertical direction scan operation V-SCAN and the horizontal direction sequential driving operation H-SD may be expressed as graphs 315 and 325 in
However, in the display device 100 that performs the vertical direction scan operation V-SCAN and the horizontal direction sequential driving operation H-SD, as illustrated as the graph 325 in
Luminance influence of adjacent light source blocks on each light source block in the display device 100 may be reduced compared with the luminance influence of the adjacent light source blocks on each light source block in the display device that performs only the vertical direction scan operation V-SCAN. For example,
For example, as illustrated in the driving timing 330 of
Further, for example, as illustrated in the driving timing 350 of
As illustrated in
Referring to
The backlight driver 170 may perform, in an odd-numbered frame, a vertical direction scan operation, and a horizontal direction sequential driving operation in a first horizontal direction in an operation S550: ODD FRAME, and in an operation S580, and may perform, in an even-numbered frame, the vertical direction scan operation, and the horizontal direction sequential driving operation in a second horizontal direction opposite to the first horizontal direction in operation S550: EVEN FRAME, and in an operation S590. In some example embodiments, each light source row of a backlight unit 160 may include first through M-th light source blocks, the horizontal direction sequential driving operation in the first horizontal direction may be an operation that sequentially drives the first through M-th light source blocks in an order from the first light source block to the M-th light source block, and the horizontal direction sequential driving operation in the second horizontal direction may be an operation that sequentially drives the first through M-th light source blocks in an order from the M-th light source block to the first light source block.
For example, as illustrated as a graph 610 in
As illustrated in
Referring to
The backlight driver 170 may divide the backlight unit 160 into horizontal regions in an operation S850, and may perform, in each horizontal region, a vertical direction scan operation that sequentially selects the light source rows of the backlight unit 160 and a horizontal direction sequential driving operation that sequentially drives the light source blocks included in the selected light source row in an operation S870. Here, each horizontal region may include two or more consecutive light source columns of the backlight unit 160.
For example, as illustrated as a graph 900 in
As described above with reference to
However, in the display device 100 that performs an operation illustrated in
Referring to
The backlight driver 170 may divide the backlight unit 160 into horizontal regions in an operation S1050, and may perform a vertical direction scan operation and a horizontal direction sequential driving operation in each horizontal region. Compared with a display device 100 performing an operation illustrated in
For example, as illustrated as a graph 1110 in
Referring to
The backlight driver 170 may divide the backlight unit 160 into horizontal regions in an operation S1250, may perform a vertical direction scan operation and a horizontal direction sequential driving operation in each horizontal region, and may further perform a frame inversion operation. Unlike the display device 100 performing an operation illustrated in
In some example embodiments, as illustrated in
In other example embodiments, as illustrated in
Referring to
The backlight driver 170 may divide the backlight unit 160 into horizontal regions in an operation S1450, may perform a vertical direction scan operation and a horizontal direction sequential driving operation in each horizontal region, and may further perform a frame inversion operation. Unlike the display device 100 performing an operation illustrated in
In some example embodiments, as illustrated as a graph 1510 in
Referring to
The backlight driver 170 may divide the backlight unit 160 into horizontal regions in an operation S1650, may perform a vertical direction scan operation and a horizontal direction sequential driving operation in each horizontal region, and may further perform a frame inversion operation, and may further perform the horizontal direction sequential driving operation in different horizontal directions with respect to an odd-numbered horizontal region and an even-numbered horizontal region in operations S1670, S1680 and S1690. In the display device 100 performing an operation illustrated in
In an embodiment, as illustrated in
In other example embodiments, as illustrated in
In an embodiment, as illustrated in
Referring to
The processor 2110 may perform various computing functions or tasks. The processor 2110 may be an application processor (AP), a micro processor, a central processing unit (CPU), etc. The processor 2110 may be coupled to other components via an address bus, a control bus, a data bus, etc. Further, in some example embodiments, the processor 2110 may be further coupled to an extended bus such as a peripheral component interconnection (PCI) bus.
The memory device 2120 may store data for operations of the electronic device 2100. For example, the memory device 2120 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.
The storage device 2130 may be a solid-state drive (SSD) device, a hard disk drive (HDD) device, a CD-ROM device, etc. The I/O device 2140 may include an input device such as a keyboard, a keypad, a mouse, a touch screen, etc, and/or an output device such as a printer, a speaker, etc. The power supply 2150 may supply power for operations of the electronic device 2100. The display device 2160 may be coupled to other components through the buses or other communication links.
The display device 2160 may perform a vertical direction scan operation that sequentially selects light source rows included in a backlight unit, and a horizontal direction sequential driving operation that sequentially drives light source blocks included in a selected light source row. Accordingly, a waterfall phenomenon where a relatively high or low luminance horizontal line image exists or gradually moves may be prevented or reduced while local dimming is performed.
The inventive concepts may be applied to any display device 2160, and any electronic device 2100 including the display device 2160. For example, the inventive concepts may be applied to a television (TV), a digital TV, a 3D TV, a smart phone, a wearable electronic device, a tablet computer, a mobile phone, 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.
The foregoing is illustrative of example embodiments and is not to be construed as limiting thereof. Although a few example embodiments have been described, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from the novel teachings and advantages of the present inventive concept. Accordingly, all such modifications are intended to be included within the scope of the present inventive concept as defined in the claims. Therefore, it is to be understood that the foregoing is illustrative of various example embodiments and is not to be construed as limited to the specific example embodiments disclosed, and that modifications to the disclosed example embodiments, as well as other example embodiments, are intended to be included within the scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| KR10-2019-0092272 | Jul 2019 | KR | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20090091265 | Song | Apr 2009 | A1 |
| 20100007682 | Kwon | Jan 2010 | A1 |
| 20110249033 | Oh | Oct 2011 | A1 |
| 20180018924 | Mao | Jan 2018 | A1 |
| Number | Date | Country |
|---|---|---|
| 10-0947527 | Mar 2010 | KR |
| Number | Date | Country | |
|---|---|---|---|
| 20210035507 A1 | Feb 2021 | US |
