EP3259751B1

EP3259751B1 - Display apparatus and method for controlling the same

Info

Publication number: EP3259751B1
Application number: EP16807831.9A
Authority: EP
Inventors: Jong-Hoon Jung; Young-Mook Park; Dae-Sik Kim
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2015-06-10
Filing date: 2016-06-10
Publication date: 2021-05-19
Anticipated expiration: 2036-06-10
Also published as: EP3259751A1; KR102185696B1; EP3259751A4; KR20160145471A

Description

[Technical Field]

Exemplary embodiments relate to a display apparatus and a method for controlling the same, and more particularly, to a display apparatus which compensates for brightness non-uniformity of a display panel and a method for controlling the same.

[Background Art]

Recently, a liquid crystal display (LCD) has become widely popular because of its appealing characteristics, such as, light weight, flat-panel, low-power operation, and so on. Accordingly, the LCD is being used in office automation (OA) equipment, audio/video devices, and diverse user terminal apparatuses. The LCD displays an image by controlling an amount of a light beam transmitted according to an image signal applied to a plurality of control switches arranged in a matrix form.
The LCD is a light receiving element which cannot emit light. Accordingly, the LCD includes a backlight having a high transmittance on a rear surface of a liquid crystal panel such that a user is able to view an image displayed on the LCD.
However, for example, because of an increased size of the panel of a large LCD, a resistance-capacitance (RC) delay of each gate line (an electrical RC delay time taken to turn on the last end pixel of the gate line) increases accordingly. When the RC delay increases, non-uniformity of screen brightness increases. In order to resolve this problem, the related art has used a method of connecting a gate driver integrated circuit (IC) to one side surface of a display panel, connecting another gate driver IC for compensating for an RC delay to the other side surface of the display panel, and applying gate power to each line of the display panel through the gate driver ICs on both side surfaces.
However, the above-described method requires that a bezel for the gate driver IC is present on each of the side surfaces of the display panel. In the case of a multi-display system where a plurality of display apparatuses are connected, as for example, in a multi-vision apparatus, a bezel mounted on a connection end of each display apparatus interrupts presentation of a view. In addition, the number of driver ICs is increased by two, and, thus, this negatively affects price competitiveness of a product.
Thus, there is a need for methods and apparatuses for compensating for brightness non-uniformity due to an RC delay even though a gate driver IC is mounted on only one side surface of a display panel.
Patent publication US 2013/0147856 A1 discloses a display device including a feedback circuit which determines an RC delay affecting a gate pulse applied to the pixels of a gate line. Compensation of the distortion due to the RC delay is achieved by adjusting a gate pulse voltage square waveform, by applying an increased voltage set according to the feedback in a starting section of the gate pulse.
Patent publication US 2010/0245317 A1 discloses a display device including a feedback circuit which determines an RC delay affecting a gate pulse applied to the pixels of a gate line. Compensation of the distortion due to the RC delay is achieved by adjusting a width of the gate pulses, so as to avoid times in which consecutive rows are simultaneously active.
Patent publication US 2014/327708 discloses an LCD display device with a backlight unit including a higher density of light sources in correspondence to pixels located far away from the scan driver, to compensate for a dropping luminance profile along the scan lines.
Patent publication EP 2 096 621 A2 discloses a drive circuit of display panel and display apparatus.
Patent publication US 2013/0235011 A1 discloses an LCD panel driving method, display circuit, and LCD device.

[Disclosure]

[Technical Problem]

Exemplary embodiments may address at least the above problems and/or disadvantages and other disadvantages not described above. Also, exemplary embodiments are not required to overcome the disadvantages described above, and may not overcome any of the problems described above.
One or more exemplary embodiments provide a display apparatus which compensates for bright non-uniformity without an RC delay even though a gate driver IC is mounted on only one side surface of a display panel and a method for controlling the same.

[Technical Solution]

According to an aspect of the invention, there is provided a display apparatus as set out in the accompanying claim 1.
The backlight driver may drive the backlight unit such that brightness of the backlight supplied to the backlight unit increases in a direction away from the gate driver IC.
The controller may generate a synchronization signal every time the gate driving voltage is applied to the gate lines and transmit the generated synchronization signal to the backlight driver. The backlight driver may drive the backlight unit to supply the backlight upon the gate driving voltage being applied based on the received synchronization signal.
The apparatus may further include a storage configured to include a lookup table where each of the plurality of pixels of the display panel is matched with a brightness value of a light source to be irradiated to each of the pixels in order to maintain brightness of the display panel consistently according to a position of each of the pixels of the display panel. The backlight driver may drive the backlight unit by using the pre-stored Lookup Table.
The backlight driver may increase the brightness of the backlight linearly.
According to another aspect of the invention, there is provided a method for controlling a display apparatus as set out in the accompanying claim 6.
The method may include increasing a brightness of a backlight supplied from a backlight unit in a direction away from the gate driver IC.

[Advantageous Effects]

According to the above-described various exemplary embodiments of the present disclosure, a difference in a display quality between a left-side pixel and a right-side pixel of a display panel due to a signal delay may be improved even though a gate driver IC is mounted on only one side surface of the display panel, and thus, a size of a bezel of the display panel may be reduced.

[Description of Drawings]

FIG. 1A is a block diagram illustrating a structure of a display apparatus according to an exemplary embodiment;
FIG. 1B is a block diagram illustrating a structure of a display panel according to an exemplary embodiment;
FIG. 2 is a block diagram illustrating a detailed structure of a display apparatus according to an exemplary embodiment;
FIG. 3A is a view provided to describe a process where a gate driving voltage is distorted thereby causing an insufficient charging time;
FIG. 3B is a view provided to describe a waveform of a gate driving voltage for compensating for an insufficient charging time according to an exemplary embodiment;
FIG. 4 is a view provided to describe a waveform of a gate driving voltage for compensating for an insufficient charging time at each frame according to feedback, according to an exemplary embodiment;
FIGS. 5A and 5B are views provided to describe a method for adjusting brightness according to a position of a backlight in order to maintain brightness of a panel consistently;
FIG. 6 is a view provided to describe a lookup table where backlight brightness values adjusted according to RC delay values are matched with the RC delay values;
FIG. 7 is a flowchart provided to describe a method for controlling a display apparatus according to an exemplary embodiment; and
FIG. 8 is a view of a backlight unit.

[Mode for Invention]

Certain exemplary embodiments are described in greater detail below with reference to the accompanying drawings.
In the following description, like drawing reference numerals are used for like elements, even in different drawings. The matters defined in the description, such as detailed construction and elements, are provided to assist in a comprehensive understanding of the exemplary embodiments. However, it is apparent that the exemplary embodiments can be practiced without those specifically defined matters. Also, well-known functions or constructions are not described in detail since they would obscure the description with unnecessary detail.
The terms used in the following description and claims are common expressions selected by considering functions in various exemplary embodiments. However, such terms may vary depending upon an intention of a person having ordinary skill in the art, legal/technical interpretation, or advent of new technology. In addition, some of the terms were selected arbitrarily by an applicant. The terms may be interpreted as defined herein. Unless otherwise defined, the terms may be interpreted based on overall descriptions of the present disclosure and common technical knowledge in the art.
In the following description and claims, a term including an ordinal, such as, 'first,' 'second,' etc., may be used to distinguish elements. The ordinal is used to distinguish the same or similar elements and does not limit the meaning of the term. For instance, ordinals do not affect an order of use or an order of arrangement of elements expressed with the ordinals. Respective ordinals may be replaced with each other, if necessary.
A term in a singular form includes a plural form unless it is intentionally written that way. In addition, in the following description, the term 'include' or 'have' refers to the disclosed feature, number, step, operation, element, part, or combination thereof and is not intended to exclude any possibilities of existence or addition of one or more other features, numbers, steps, operations, elements, parts or combination thereof.
In the following description, the term 'module,' 'unit,' or 'part' refers to an element which performs at least one function or operation. The 'module,' 'unit,' or 'part' may be realized as hardware, software, or combination thereof. In addition, a plurality of 'modules,' 'units,' and 'parts' may be integrated into at least one module or chip such that it may include at least one processor except for a case where respective 'modules,' 'units,' and 'parts' need to be realized as discrete specific hardware.
When it is described that one part is connected to another part, the connection includes a direct connection of the parts and an indirection connection through other medium. In addition, the description that a certain part includes an element signifies that the part may further include other elements rather than signifying that the part excludes other elements, unless otherwise described.
The exemplary embodiments of the present disclosure may be diversely modified. Accordingly, specific exemplary embodiments are illustrated in the drawings and are described in detail in the detailed description. However, it is to be understood that the present disclosure is not limited to a specific exemplary embodiment, but includes all modifications, equivalents, and substitutions without departing from the scope and spirit of the present disclosure. Also, well-known functions or constructions are not described in detail since they would obscure the disclosure with unnecessary detail.
FIG. 1A is a block diagram illustrating a structure of a display apparatus according to an exemplary embodiment. FIG. 1B illustrates a display panel according to an exemplary embodiment.
According to an exemplary embodiment, a display apparatus 100 may include various types of image-processable monitors including a television (TV), a smart phone, a portable terminal, a mobile terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a computer, a laptop computer, a notepad, a wireless broadband Internet (WiBro) terminal, a tablet personal computer (PC), a smart TV, and the like.
Referring to FIG. 1A, the display apparatus 100 according to an exemplary embodiment includes a display panel 110, a source driver IC 120, a gate driver IC 130, and a controller 140.
The display panel 110 displays image data. For example, the display panel 110 may include a gate-in-panel (GIP) structure where a gate line is installed in a panel. For example, the display panel 110 may include a thin film transistor-LCD (TFT-LCD) panel, but this is not limiting. That is, a display panel of an exemplary embodiment may include any other appropriate display panel.
For example, a TFT-LCD has a matrix-type pixel structure. For example, in this structure, a plurality of gate lines intersect a plurality of data lines perpendicularly, and a pixel region is formed between each gate line and each data line. The pixel region includes a TFT and a liquid crystal to display a screen. A pixel includes an electrode layer including an upper electrode and a lower electrode. The upper electrode refers to a pixel electrode, and the lower electrode refers to a common electrode. An on/off state of the TFT is controlled depending upon a level of a gate voltage applied to the gate lines. In response to the TFT being turned on, a data voltage applied through the data lines is supplied to a pixel electrode of a corresponding pixel, and display of the pixel is performed according to a difference between the data voltage and a voltage applied to a common electrode.
The display panel 110 is connected with the source driver IC 120 and the gate driver IC 130. A gate driving voltage and a data voltage are supplied to the display panel 110 through the gate driver IC 130 and the source driver IC 120, respectively.
FIG. 1B illustrates a display panel 110 according to an exemplary embodiment.
The display panel 110 includes an LCD panel in which liquid crystal cells are arranged in a matrix form. The display panel 110 includes a plurality of gate lines GL1 and GL2 to GLN, a plurality of data lines DL1 and DL2 to DLN, a plurality of TFTs T1 and T2 to TN, and a plurality of capacitors C1 and C2 to CN. Although only one gate line is illustrated to have TFTs and capacitors, the remaining data lines GL2 to GLN have similar components.
The plurality of gate lines GL1 and GL2 to GLN receives a plurality of gate signals from a gate driver IC 130.
The plurality of data lines DL2, DL2,... and DLN crosses the plurality of gate lines and receives a data voltage from a source driver IC 120 corresponding to a data signal.
The plurality of TFTs T1, T2,..., and TN is formed at an intersection of the gate lines GL1 and GL2 to GLN and the data lines DL1, DL2,..., and DLN. Each of the capacitors C1, C2, ...., CN, which are connected between the TFTs and a voltage generator 96 supplying a voltage, form a single pixel. A gate electrode of the each TFT is connected to the gate lines GL1 and GL2 to GLN, and a source electrode of the TFT is connected to the data lines DL1, DL2,... and DLN. Each pixel area (not shown) is formed at an intersection of the gate lines GL1 and GL2 to GLN and the data lines DL1, DL2,... and DLN, and a pixel electrode is formed in the pixel area.
The plurality of capacitors C1, C2, ...., CN includes the pixel electrode, the common electrode which receives a common voltage from the voltage generator 96, and liquid crystal which is interposed between the pixel electrode and the common electrode.
If a predetermined signal is applied from the gate lines GL1 and GL2 to GLN and the data lines DL1, DL2,... and DLN to turn on the TFTs T1, T2,..., and TN, a data voltage which is supplied to the data lines DL1, DL2,..., and DLN is applied to a pixel electrode through the TFTs. An electric field which falls under a difference between a data voltage applied to the pixel electrode and a common voltage supplied by the voltage generator 96 is applied to the capacitors C1, C2, ...., CN and light passes through at the transmissivity ratio corresponding to the strength of the electric field.
An array structure of a source driver IC and a gate driver IC in a display panel may be divided into a single bank structure where one source driver IC and one gate driver IC are arrayed on only a certain side of the display panel (see reference numerals 80, 82 in FIG. 1B) and a dual bank structure where two source driver ICs and two gate driver ICs are arrayed on both sides of the display panel. As shown in FIG. 1B, there is no source driver IC and no gate driver IC on sides 84, 86 of the display panel 110.
As a display panel is becoming larger and a multi-vision technology develops, a dimension occupied by the source driver IC and the gate driver IC needs to be reduced. The single bank structure is more desirable in this regard, but the single bank structure is not widely used due to a signal delay which occurs at a gate line in a display panel in the single bank structure.
For example, when the gate driver IC is disposed on a left side of the display panel and the gate driving voltage is applied to any arbitrary gate line, a gate driving voltage which is actually measured at the rightmost position of the gate line (a position of CN on one of the corresponding gate lines closest to a right side 84 in FIG. 1B) has a waveform which is delayed more than a gate voltage which is actually measured at the leftmost position of the gate line (a position of C1 on one of the corresponding gate lines closest to a left side 80 in FIG. 1B). Accordingly, a kickback voltage of a pixel region at each position varies depending upon the delay of the gate driving voltage since a charge is supplied through a TFT of a pixel at a corresponding position during a predetermined period of time of applying a delayed waveform of the gate driving voltage. For example, even though a data voltage in the same gradation is applied to a pixel of one line, a left-side pixel which is closest to the gate driver IC and a right-side pixel which is farthest from the gate driver IC are charged with different voltages. A difference in the charged voltages causes deterioration of a display quality due to a difference in brightness of a left-side pixel, e.g., corresponding to C1, and a right-side pixel, e.g., corresponding to CN, of the display panel, a direct current (DC) stress with respect to a liquid crystal material, and an afterimage problem, which degrades image quality. The controller 140 is a component for resolving the above-described problems. The controller 140 controls overall operations of the display apparatus 100.
For example, the controller 140 may receive a feedback signal Fb on a gate driving voltage applied to at least one pixel among a plurality of pixels and detect distortion of the gate driving voltage applied to the at least one pixel based on the feedback. In order to compensate for the distortion of the gate driving voltage, the controller 140 may adjust a level of a gate driving voltage applied to the gate lines and apply the adjusted gate driving voltage to the gate lines.
That is, at least one of the plurality of pixels included in the gate lines may be connected to the controller 140 and supply the applied gate driving voltage to the controller 140 as a feedback voltage. For example, the pixel which supplies the feedback voltage to the controller 140 is a pixel where the most intense distortion of the gate driving voltage occurs among the pixels included in the gate lines, that is, a pixel located at a position which is farthest from the gate driver IC 130.
FIG. 2 is a block diagram illustrating a detailed structure of a display apparatus according to an exemplary embodiment.
Referring to FIG. 2, a timing controller 150 controls a timing at which a data voltage and a gate driving voltage are applied. For example, the timing controller 150 receives RGB data, that is, a chrominance signal, a horizontal synchronization (H-SYNC) signal, a vertical synchronization (V-SYNC) signal, a clock signal (MCLK), and a data enable signal (DE). The timing controller 150 may receive voltages supplied from a voltage generator (not shown), adjust a timing of the signals, and generate signals for driving the display panel 110.
The timing controller 150 converts a format of the RGB data to correspond to a specification of an interface of the source driver IC 120 and outputs the converted RGB data through the source driver IC 120. In addition, the timing controller 150 outputs a data control signal (for example, an output start signal (TP), a horizontal start signal (STH), and a clock signal (HCLK)) through the source driver IC 120 and outputs a gate control signal (for example, a vertical start signal (STV), a gate clock signal (CPV), and an output enable signal (OE)) through the gate driver IC 130.
The source driver IC 120 may receive a gradation voltage generated in the voltage generator through the timing controller 150, select a proper gradation voltage according to the RGB data, convert the selected gradation voltage into a voltage which may be applied to the display panel 110, and apply the converted voltage to each data line of the display panel 110.
For example, the source driver IC 120 selects gradation voltages corresponding to the RGB data among the generated gradation voltages in response to the data control signal (TP, STH, and HCLK) transmitted from the timing controller 150 and apply the selected gradation voltages to each data line of the display panel 110.
The gate driver IC 130 may receive a gate voltage generated in the voltage generator through the timing controller 150, convert the received gate voltage into a voltage which may be applied to the display panel 110, and apply the converted voltage to each gate line of the display panel 110.
For example, the gate driver IC 130 receives a gate-on voltage (Von) and a gate-off voltage (Voff) and outputs a gate driving voltage having the gate-on voltage (Von) sequentially in response to the gate control signal (STV, CPV, and OE) transmitted from the timing controller 150. The gate driving voltage is applied to the gate lines of the display panel 110 sequentially and scans the gate lines sequentially. For example, the display apparatus 100 may further include a regulator configured to convert an input voltage into a gate-on voltage (Von) and a gate-off voltage (Voff) and output the converted voltages.
In response to the gate signals sequentially being applied to the gate lines, the data signals are applied to the data lines in synchronization with the gate signals. In response to the gate signal being applied to the selected gate line, a TFT connected to the selected gate line is turned on according to the gate signal. In response to the data signal being applied to the data line connected to the TFT which has been turned on, the applied data signal is charged into a liquid crystal capacitor and a storage capacitor by passing the turned-on TFT.
The liquid crystal capacitor controls light transmittance of a liquid crystal according to the charged voltage. The storage capacitor may maintain a charged state of the liquid crystal capacitor by accumulating the data signal in response to the TFT being turned on and applying the accumulated data signal to the liquid crystal capacitor in response to the TFT being turned off. The display panel 110 may display an image in this manner.
As illustrated in FIG. 2, the controller 140 may be disposed between the timing controller 150 and the gate driver IC 130. The controller 140 may receive a timing signal for controlling a timing at which the data voltage and the gate driving voltage are applied from the timing controller 150.
The controller 140 may apply the gate driving voltage of which level has been adjusted to the gate lines according to the timing signal applied from the timing controller 150. As the controller 140 applies the adjusted gate driving voltage to the gate lines, a charging time of each pixel may be compensated according to the original gate driving voltage even though the applied gate driving voltage is distorted. The controller 140 may be referred to as 'compensation circuit' in this regard.
For example, the gate driving voltage may be applied to the gate lines as a square wave. In order to compensate for an insufficient charging time which occurs in at least one pixel due to the distorted gate driving voltage, the controller 140 may raise a level of a voltage of a section in which the insufficient charging time occurred in the square wave. For example, the square wave may raise a level of a voltage of a section after a certain period of time from when a gate is changed from an OFF state to an ON state (OFF-ON section) and a section before a certain period of time from when the gate is changed from the ON state to the OFF state (ON-OFF section). The detailed description will be provided below with reference to FIG. 3.
The voltage generator may generate and supply a voltage for driving the display panel 110. That is, the voltage generator may generate a gate-on/off voltage, a gradation voltage, and/or a common electrode voltage and supply the generated voltage to the timing controller 150. The voltage generator may be the same as the voltage generator 96 of FIG. 1B or different.
The display panel 110 may receive a backlight from the backlight unit 160 and the backlight driver 170.
The backlight unit 160 may be disposed on a rear surface of the display panel 110. The backlight unit 160 may supply a light with desired brightness to the display panel 110 in response to a driving signal transmitted from the backlight driver 170. The backlight unit 160 may include a plurality of light sources. The plurality of light sources may include a plurality of light emitting diodes (LEDs) (refer to FIG. 8). The plurality of LEDs may be connected to each other in series on a printed circuit board (PCB) forming a plurality of blocks.
The backlight driver 170 may generate a clock signal and a brightness data signal which synchronizes with the clock signal in response to an enable signal. The brightness data signal includes brightness information for controlling brightness of the backlight unit 160.
FIG. 3A is a view provided to describe a process where a gate driving voltage is distorted thereby causing an insufficient charging time.
As illustrated in FIG. 3A, a gate driving voltage which is applied through the gate driver IC 130 during one horizontal scanning period (one frame) has a waveform 31, e.g., a square wave. A pulse of the gate driving voltage is formed with a width allowing a sufficient charging time for each pixel. An amplitude of the gate driving voltage is formed to be higher than a gate-on level of a field effect transistor (FET) element. Upon the gate driving voltage being applied to each gate line of the display panel 110, distortion according to an RC delay occurs. The distortion may weaken a charging characteristic of each pixel.
More particularly, a waveform of the gate driving voltage is changed to a waveform 32 where a high-level section becomes shorter according to the distortion, and, thus, a charging time of a pixel becomes insufficient, which becomes worse as a signal delay becomes greater. Specifically, the distortion appears more intense at a pixel located at a position which is farthest from the gate driver IC 130 among the plurality of pixels of the gate line. As a sufficient charging time of a pixel is not achieved, deterioration of a contrast ratio and bright non-uniformity may occur. Specifically, such problems occur intensely when a data voltage has a broad amplitude, for example, high voltage driving.
FIG. 3B is a view provided to describe a waveform of a gate driving voltage for compensating for an insufficient charging time, according to an exemplary embodiment.
Referring to FIG. 3B, in order to compensate for an insufficient charging time which occurs in at least one pixel due to the distorted gate driving voltage, the controller 140 may control to raise a level of a voltage of one or more sections 36 in which the insufficient charging time is predicted to occur in a current frame based on a received feedback signal providing information about the previous frame, and apply the higher voltage value in a section of the square wave. For example, an amplitude of a section in which an insufficient charging time in a waveform of the gate driving voltage, that is, a section in which a loss of charging time occurs due to the distortion, may be higher than the gate-on level voltage. For example, the amplitude of the section which the loss of charging time occurs may be formed to be high enough to secure a high-level section for allowing a sufficient charging time despite occurrence of the distortion.
As illustrated in FIG. 3B, the controller 140 may apply the gate driving voltage having a waveform 33 for compensating for the signal loss due to the distortion, to each gate line of the display panel 110. For example, the gate driving voltage may be changed to a gate driving voltage having a distorted waveform 34 while passing the pixels of the gate line.
The gate driving voltage having the distorted waveform 34 secures a charging time of the gate driving voltage before distortion even though it is distorted, by having an amplitude of sufficiently high value for a duration of a certain charging time, and thus, a difference in a charging voltage of the pixels due to the RC delay along the gate line may be substantially eliminated. In addition, it is possible to avoid unnecessary application of an excessive voltage to each of the pixels, by increasing an amplitude size only in one or more sections of the waveform where a certain distortion is expected, rather than increasing an amplitude size of an entire square wave. Accordingly, the charging time of each pixel may be secured even though the distortion might still occur due to the RC delay.
Hereinafter, the compensated gate driving voltage which may compensate for the distortion will be called 'compensation gate driving voltage' for convenience of description.
FIG. 4 is a view provided to describe a waveform of a gate driving voltage for compensating for an insufficient charging time at each frame according to feedback, according to an exemplary embodiment.
As illustrated in FIG. 4, the controller 140 may apply the compensation gate driving voltage to each gate line at each frame. For example, the compensation gate driving voltage applied to each gate line may have a different form according to a degree of distortion of the gate driving voltage at each frame.
For example, in response to a first gate driving voltage being applied to a gate line at a certain frame, an OFF-ON section 38 and an ON-OFF section 40 of a waveform 41 of a first gate signal of the gate driving voltage may have a higher value than a gate-on level 44 by an amount of a first height h1. In response to a second gate driving voltage being applied to a gate line at a subsequent frame, an OFF-ON section 38 and an ON-OFF section 40 of a waveform 42 of a second gate signal of the gate driving voltage may have a higher value than the gate-on level 44 by an amount of a second height h2 smaller than the first height h1. In response to an Nth gate driving voltage being applied to a gate line at a last frame, an OFF-ON section 38 and an ON-OFF section 40 of a waveform 46 of an Nth gate signal of the gate driving voltage may have a higher value than the gate-on level 44 by an amount of the first height h1 or any other appropriate amount. That is, the signal corresponding to the compensation gate driving voltage applied to each frame may have a different waveform with sections having different amplitude or amplitudes, which may be determined by a gate driving voltage which is fed back from a previous frame.
For example, the controller 140 may receive feedback on a gate driving voltage applied to at least one pixel among the plurality of pixels of the gate line. For example, the controller 140 may receive feedback on a gate driving voltage applied to at least one pixel located at a position which is farthest from the gate driver IC 130 among the plurality of pixels of each gate line. The controller 140 may receive, as a feedback signal, the gate driving voltage which has been most recently applied, from a pixel at the gate line, and detect the distortion based on the received gate driving voltage. For example, the pixel may be a pixel disposed at a farthest position from the gate driver IC, on a gate line, e.g., a pixel corresponding to the capacitor CN. The controller 140 may quantify an amount of distortion of the gate driving voltage applied to the pixel by comparison with an undistorted normal gate driving voltage and generate a compensation gate driving to compensate the amount of distortion of the voltage signal amplitude, for example, by adding a comparison difference value to the undistorted voltage signal value. The generated compensation gate driving voltage may be applied to a gate line at a subsequent frame to reduce a difference in the charging voltages in the frame.
A waveform of the compensation gate driving voltage is determined according to the amount of distortion detected based on the feedback on the gate driving voltage, and thus, a compensation gate driving voltage at each frame may have a different form.
FIGS. 5A and 5B are views provided to describe a method for adjusting brightness according to a position of a backlight in order to maintain brightness of a panel consistently.
FIG. 5A illustrates brightness of a backlight when a backlight unit for supplying a backlight to a display panel provides consistent brightness regardless of a position of a pixel.
According to FIG. 5A, a level of a driving voltage according to a position of a backlight may be expressed as a graph 50. In the graph 50, a horizontal axis represents a position of the backlight unit 160, e.g., a position of a light source of the backlight unit, corresponding to each pixel at one gate line, and a vertical axis represents a level of a driving voltage of the backlight driver 170 at each position. That is, the backlight driver 170 applies a consistent driving voltage regardless of a position of the backlight unit 160.
For example, as illustrated in a graph 52 of FIG. 5A, in response to a consistent driving voltage being applied to the backlight unit 160 regardless of the position on the backlight unit 160, a difference may occur between the brightness of the backlight unit 160 (graph 54) and the brightness of the display panel 110 (graph 56). For example, the brightness of a pixel which is far from the gate driver IC 130 may be relatively lower than the brightness of a pixel which is closer to the gate driver IC 130 according to the difference in the charging time due to the RC delay.
A brightness difference according to a difference in a charging time may be minimized by applying a different level of driving voltages according to the position of the light source of the backlight unit 160. As illustrated in a graph 57 of FIG. 5B, the backlight driver 170 may drive the backlight unit 160 such that the brightness of the backlight supplied to the backlight unit 160 increases in a direction 58 away from the gate driver IC 130. For example, the backlight driver 170 may increase the brightness of the backlight linearly or non-linearly.
For example, an imbalance of the brightness due to the insufficient charging time may be compensated by the backlight 160 which increases the brightness in the direction away from the gate driver IC 130. Accordingly, as illustrated in graph 59 of FIG. 5B, the brightness supplied by the backlight unit 160 (graph 54) may increase in the direction away from the gate driver IC 130 such that the brightness of the display panel 110 (graph 56) is maintained at a consistent level regardless of a distance of a pixel from the gate driver IC 130. That is, the backlight driver 170 may compensate for the imbalance between the left-side brightness and the right-side brightness of the display panel 110 by driving the backlight such that the backlight driving voltage is applied differently at each position of the light source of the backlight unit 160.
A brightness value provided by each light source of the backlight unit 160 to compensate for the imbalance between left-side brightness and right-side brightness of the display panel 110 may be preset and stored in advance, for example, during a manufacturing process.
For example, the display apparatus 100 may further include a storage device 98 (refer to FIG. 1). The storage may include a lookup table where each of the plurality of pixels of the display panel is matched with a brightness value of a light source which needs to be irradiated to each of the pixels in order to maintain the brightness of the display panel consistently according to a position of each of the pixels of the display panel.
FIG. 6 is a view provided to describe a lookup table 60 where backlight brightness values adjusted according to RC delay values are matched with the RC delay. As illustrated in FIG. 6, the backlight driver 170 may drive the backlight unit 160 by using the lookup table stored in the storage.
As illustrated in FIG. 6, the lookup table matches and stores RC delay values and brightness values of a backlight in such a way that a brightness value of an adjusted backlight increases toward a pixel having a great RC delay value. The brightness value of the backlight unit 160 according to the RC delay may be measured and stored as a predetermined value in a design and manufacturing process of the display apparatus 100.
FIG. 6 illustrates only four RC delay values which are matched with the corresponding brightness values, but brightness values of the light sources corresponding to different ones and/or more RC delay values may be stored.
As shown in FIG. 8, in the backlight unit 160, a position of a light source may be adjusted, e.g., by a physical position or by appropriate control of activation function, such that the brightness of the pixels of each gate line is consistent.
That is, a distance between the light sources which supply a backlight to each pixel of the gate lines may be adjusted in such a way that the light sources 800 located closer to the gate driver IC 130 are arranged with a greater distance therebetween, and the light sources 810 located farther away from the gate driver IC 130 are arranged with a smaller distance therebetween.
Accordingly, the brightness of the backlight by the light sources 810 located farther away from the gate driver IC 130 is made higher than the brightness of the backlight by the light sources 800 located closer to the gate driver IC 130. Accordingly, the brightness difference may further offset the brightness difference due to the difference in the charging time and reduce the imbalance of the brightness of the display panel 110. For example, the brightness of the backlight unit 160 according to the RC delay may be measured in the design and manufacturing process of the display apparatus 100, and the light sources of the backlight unit 160 may be arranged with the adjusted distance such that the brightness of the display panel 110 is maintained consistently based on the measured brightness values.
FIG. 7 is a flowchart provided to describe a method for controlling a display apparatus according to an exemplary embodiment.
On the display panel, feedback on a gate driving voltage applied to at least one pixel among a plurality of pixels arranged at an intersection of data lines to which a data voltage is applied by a source driver IC and gate lines to which a gate driving voltage is applied by a gate driver IC is received in operation S710. For example, the gate driving voltage may be applied as a square wave.
For example, feedback on a gate driving voltage applied to at least one pixel located at a position which is farthest from the gate driver IC among the plurality of pixels may be received.
Subsequently, distortion of the gate driving voltage applied to at least one pixel is detected based on the feedback in operation S720.
A level of the gate driving voltage applied to the gate lines is adjusted to compensate for the distortion of the gate driving voltage in operation S730. For example, in order to compensate for an insufficient charging time which occurs in at least one pixel due to the distortion of the gate driving voltage, a level of a voltage of a section which the insufficient charging time occurred in a square wave may be raised.
The adjusted gate driving voltage is applied to the gate lines in operation S740. The adjusted gate driving voltage may be applied according to a timing signal applied from a timing controller for controlling a timing at which a data voltage and a gate driving voltage are applied.
The brightness of a backlight supplied to a backlight unit may be increased in a direction away from the gate driver IC. For example, a synchronization signal may be generated every time the gate driving voltage is applied to the gate lines, and the backlight may be supplied upon the gate driving voltage being applied based on the generated synchronization signal. According to a position of each pixel of the display panel, the brightness of the backlight may be increased by using a lookup table where each of the plurality of pixels of the display panel is matched with a brightness value of a light source to be irradiated to each of the pixels in order to maintain brightness of the display panel consistently according to a position of each of the pixels of the display panel. For example, the brightness of the backlight may be increased linearly.
According to the above-described teaching, deterioration of the brightness uniformity due to a signal delay at a gate line may be improved by reducing a difference in a charging voltage amount of a left-side pixel and a right-side pixel of a display panel.
According to the above-described various exemplary embodiments, the method for controlling a display apparatus may be realized as a program and stored in diverse type of recording mediums. That is, a computer program which is processed by a various processors and executes the above-described methods may be stored in a recoding medium and executed.
As an example, a non-transitory computer-readable medium, including a program for executing operations of receiving feedback on a gate driving voltage applied to at least one pixel among a plurality of pixels arranged at an intersection of data lines to which a data voltage is applied by a source driver IC and gate lines to which a gate driving voltage is applied by a gate driver IC, detecting distortion of the gate driving voltage applied to at least one pixel based on the feedback, adjusting a level of the gate driving voltage applied to the gate lines to compensate for the distortion of the gate driving voltage, and applying the adjusted gate driving voltage to the gate lines, may be provided.
The non-transitory computer-readable recording medium refers to a medium which may store data permanently or semi-permanently rather than storing data for a short time, such as, register, cache, memory, and the like, and may be readable by an apparatus. For example, the above-described various applications and programs may be stored in and provided through the non-transitory computer-readable recording medium, such as, compact disc (CD), digital versatile disk (DVD), hard disk, Blu-ray disk, universal serial bus (USB), memory card, Read-Only Memory (ROM), and the like.
Although a few exemplary embodiments have been shown and described, it would be appreciated by those skilled in the art that changes may be made in the exemplary embodiments without departing from the scope of the claims.

Claims

A display apparatus (100) comprising:
a display panel (110) configured to include a plurality of pixels arranged at intersections of data lines and gate lines;

a source driver integrated circuit, IC, (120) configured to be disposed on one side surface of the display panel to apply a data voltage to the data lines;

a gate driver IC (130) configured to be disposed on one of two side surfaces of the display panel that are adjacent to the one side surface of the display panel, to apply gate driving voltage pulses to the gate lines;

a controller (140) configured to receive a feedback signal comprising information on the gate driving voltage applied to one pixel among the plurality of pixels, detect a distortion of the gate driving voltage applied to the one pixel based on the feedback signal, adjust a level of the gate driving voltage pulses applied to the gate lines according to an amount of the detected distortion of the gate driving voltage to compensate for the distortion of the gate driving voltage, and apply the adjusted gate driving voltage pulses to the gate lines via the gate driver IC (130);

a backlight unit (160) configured to supply a backlight to the display panel; and

a backlight driver (170) configured to drive the backlight unit,

wherein the one pixel is located at a position farthest away from the gate driver IC on the gate line to which the one pixel is connected, and wherein each of said gate driving voltage pulses consists of a first section, a middle section subsequent to the first section and a last section subsequent to the middle section, and

the controller (140) is configured to adjust the gate driving voltage pulses by increasing the level of the voltage only in the first section and in the last section of said pulses, according to the amount of the detected distortion.
The apparatus as claimed in claim 1,
wherein the backlight driver is configured to drive the backlight unit such that a brightness of the backlight supplied from the backlight unit increases in a direction away from the gate driver IC.
The apparatus as claimed in claim 1, wherein the controller is configured to generate a synchronization signal every time the gate driving voltage is applied to the gate lines and transmit the generated synchronization signal to the backlight driver,
wherein the backlight driver is configured to drive the backlight unit to supply the backlight upon the gate driving voltage being applied based on the received synchronization signal.
The apparatus as claimed in claim 3, further comprising:
a storage configured to pre-store a lookup table where each of the plurality of pixels of the display panel is matched with brightness values of light sources of the backlight unit to be irradiated to the pixels in order to maintain the brightness of the display panel at a certain consistent level according to a position of each of the pixels of the display panel,

wherein the backlight driver is configured to drive the backlight unit by using the pre-stored lookup table.
The apparatus as claimed in claim 2, wherein the backlight driver is configured to linearly increase the brightness of the backlight in the direction away from the gate driver IC.
A method for controlling the display apparatus of claim 1, the method comprising:
receiving, as a feedback signal, information on the gate driving voltage, which has been applied to said one pixel located at a position farthest away from the gate driver IC (S710);

detecting a distortion of the gate driving voltage applied to the one pixel based on the feedback signal (S720);

adjusting a level of the gate driving voltage pulses applied to the gate lines according to the amount of the detected distortion of the gate driving voltage to compensate for the distortion of the gate driving voltage (S730);

applying the adjusted gate driving voltage pulses to the gate lines (S740); and

applying a level of driving voltage to the backlight unit,

wherein each of said gate driving voltage pulses consists of a first section, a middle section subsequent to the first section and a last section subsequent to the middle section, and the method comprises adjusting the gate driving voltage pulses by increasing the level of the voltage only in the first section and in the last section of said pulses, according to the amount of the detected distortion.
The method as claimed in claim 6, further comprising:
increasing a brightness of a backlight supplied from the backlight unit in a direction away from the gate driver IC.