KR20080080867A - Display device and the driving method thereof - Google Patents

Abstract

A display apparatus and a driving method thereof are provided to prevent reduction of luminance by compensating for luminance of plural backlight unit pixels using compensation gray scales. A display apparatus includes a panel assembly and a backlight unit(40'). The panel assembly includes plural gate lines for transmitting gate signals, plural data lines for transmitting data signals, and plural pixels defined by the gate and data lines. The backlight unit includes plural scan lines for transmitting scan signal, plural column lines for transmitting illumination data signals, and plural backlight unit pixels defined by the scan and column lines. The backlight unit determines a first gray scale of a first backlight unit pixel and converts the first gray scale into a second gray scale using a compensation gray scale corresponding to loss luminance in the first backlight unit pixel based on plural pixels corresponding to the first backlight unit pixel which is positioned at an outermost of the plural backlight unit pixels.

Description

DISPLAY DEVICE AND THE DRIVING METHOD THEREOF}

1 is an exploded perspective view of a liquid crystal display according to a first exemplary embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view of the liquid crystal panel assembly shown in FIG. 1.

3 is a partially cutaway perspective view of the backlight unit according to the first embodiment of the present invention.

4 is a partial cross-sectional view of the fourth substrate and the electron emission unit illustrated in FIG. 3.

5 is a partial plan view of an electron emission unit of a backlight unit according to a second embodiment of the present invention.

6 is a partial cutaway perspective view of a backlight unit according to a third exemplary embodiment of the present invention.

7 is a block diagram illustrating a display device according to a third exemplary embodiment of the present invention.

8A and 8B specifically illustrate driving waveforms of the backlight unit according to the third embodiment of the present invention.

The present invention relates to a display device, and more particularly, to a display device including a backlight unit operating in synchronization with a display image.

A liquid crystal display device, which is a type of flat panel display device, is a display device that realizes a predetermined image by varying light transmittance for each pixel by using dielectric anisotropy of a liquid crystal whose twist angle changes according to an applied voltage. Such a liquid crystal display device has advantages such as light weight, thickness, and low power consumption compared to a cathode ray tube, which is a typical image display device.

The liquid crystal display basically includes a liquid crystal panel assembly and a backlight unit positioned behind the liquid crystal panel assembly to provide light to the liquid crystal panel assembly.

When the liquid crystal panel assembly is composed of an active liquid crystal panel assembly, the liquid crystal panel assembly includes a pair of transparent substrates, a liquid crystal layer positioned between the transparent substrates, a polarizing plate disposed on the outer surfaces of the transparent substrates, and either transparent A color filter that provides red, green, and blue colors to the common electrode provided on the inner surface of the substrate, the pixel electrodes and switching elements provided on the inner surface of the other transparent substrate, and the three sub-pixels constituting one pixel. And the like.

The liquid crystal panel assembly receives light emitted from the backlight unit and transmits or blocks the light by the action of the liquid crystal layer to realize a predetermined image.

The backlight unit may be classified according to the type of light source, and one of them is known as a cold cathode fluorescent lamp (CCFL). Since the CCFL is a line light source, the light generated from the CCFL can be evenly distributed toward the liquid crystal panel assembly through the optical members such as the diffusion sheet, the diffusion plate, and the prism sheet.

However, in the CCFL method, since light generated in the CCFL passes through the optical member, significant light loss occurs. In general, in the CCFL type liquid crystal display, the light passing through the liquid crystal panel assembly is known to correspond to about 3 to 5% of the CCFL generated light. In addition, the CCFL type backlight unit consumes a large portion of the total power consumption of the liquid crystal display due to large power consumption, and it is difficult to apply to a large liquid crystal display device having a size of 30 inches or more because of the large area of the CCFL structure.

As a conventional backlight unit, a light emitting diode (LED) method is known. A plurality of LEDs are usually provided as a point light source, and are combined with optical members such as a reflective sheet, a light guide plate, a diffusion sheet, a diffusion plate, and a prism sheet to constitute a backlight unit. This LED method has the advantages of fast response speed and excellent color reproducibility, but has a disadvantage of high price and large thickness.

As such, the conventional backlight unit has its own problems depending on the type of light source. In addition, since the conventional backlight unit is always turned on at a constant brightness when the liquid crystal display is driven, it is difficult to meet the image quality improvement required for the liquid crystal display.

For example, when the liquid crystal panel assembly displays an arbitrary screen including a bright portion and a dark portion in accordance with an image signal, the backlight unit displays the liquid crystal panel pixels portion displaying the bright portion and the liquid crystal panel pixels displaying the dark portion. If you provide light of different intensity to the part, you can realize a screen with excellent dynamic contrast.

In addition, the light emitting parts of the liquid crystal panel assembly and the backlight unit were manufactured in the same size. In this case, the plurality of backlight unit pixels positioned at the outermost part of the backlight unit may have a problem in that the luminance of the plurality of backlight unit pixels is lost due to loss of light. Therefore, by compensating for the lost luminance, it is possible to prevent a phenomenon that the luminance is lowered in the plurality of pixels located at the outermost side.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and to provide a display device and a method of driving the same, which compensates for the luminance lost in the plurality of backlight unit pixels located at the outermost side, thereby preventing the luminance from falling. .

In order to achieve the above object, a display device according to an aspect of the present invention includes a plurality of gate lines for transmitting a plurality of gate signals, a plurality of data lines for transmitting a plurality of data signals, and a plurality of gate lines and the plurality of gate lines. A panel assembly including a plurality of pixels defined by a data line, a plurality of scan lines for transmitting a plurality of scan signals, a plurality of column lines for transmitting a plurality of light emitting data signals, and a plurality of scan lines and the plurality of scan lines And a backlight unit having a plurality of backlight unit pixels defined by column lines, wherein the backlight unit corresponds to a first backlight unit pixel located at an outermost position among the plurality of backlight unit pixels. The first grayscale of the first backlight unit pixel is determined according to the grayscales of the plurality of pixels, and the first back Using the compensated gradation corresponding to the luminance loss on the byte unit pixel and changing the first tone to the second tone.

A driving method of a display device according to another aspect of the present invention, comprising: a panel assembly having a plurality of pixels and a backlight unit having a plurality of backlight unit pixels, comprising: a) the plurality of backs Determining a first gray level of the first backlight unit pixel positioned at the outermost part of the light unit pixels, and b) using the first gray level using a compensation gray level corresponding to the luminance lost in the first backlight unit pixel. Changing to the second gray level. In the step b), the luminance loss generated in the first backlight unit pixel is compensated for using the second gray scale. Also, the step a) may include determining a first gray level of the first backlight unit pixel according to the gray levels of the plurality of pixels corresponding to the pixels of the first backlight unit. In this case, step b) may include transmitting the light emission data signal generated according to the second digital data corresponding to the second grayscale to the first backlight unit pixel, and the first digital corresponding to the first grayscale. And transmitting the light emission data signal generated according to the data to the backlight unit pixels except for the first backlight unit pixel.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention. Like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is "connected" to another part, this includes not only the "directly connected" but also the "electrically connected" between other elements in between. In addition, when a part is said to "include" a certain component, this means that it may further include other components, except to exclude other components unless otherwise stated.

1 is an exploded perspective view of a liquid crystal display according to a first exemplary embodiment of the present invention.

Referring to the drawings, the liquid crystal display device 100 of the present embodiment has a liquid crystal panel assembly 10 having arbitrary pixels along the row direction and the column direction, and smaller than the liquid crystal panel assembly 10 along the row direction and the column direction. And a backlight unit 40 having a number of pixels and positioned behind the liquid crystal panel assembly 10 to provide light to the liquid crystal panel assembly 10.

Here, the row direction may be defined as one direction of the liquid crystal display 100, for example, a horizontal direction of the screen implemented by the liquid crystal panel assembly 10 (for example, the x-axis direction in the drawing), and the column direction may be defined as the liquid crystal display. Another direction of 100 may be defined as, for example, a vertical direction (for example, y-axis direction in the drawing) of the screen implemented by the liquid crystal panel assembly 10.

The number of pixels of the liquid crystal panel assembly 10 and the number of pixels of the backlight unit 40 in the row direction are referred to as M and M ', respectively, and the number of pixels and the backlight unit of the liquid crystal panel assembly 10 in the column direction ( When the number of pixels 40 is N and N ', respectively, the resolution of the liquid crystal panel assembly 10 may be expressed as M x N, and the resolution of the backlight unit 40 may be expressed as M' x N '.

In the present exemplary embodiment, M and N representing the number of pixels of the liquid crystal panel assembly 10 may be defined as integers of 240 or more, respectively, and M 'and N' representing the number of pixels of the backlight unit 40 are 2 to 99, respectively. Can be defined as any one of the integers. The backlight unit 40 includes a self-luminous display panel having a resolution of M 'x N'.

Thus, one pixel of the backlight unit 40 is positioned corresponding to two or more pixels of the liquid crystal panel assembly 10. In addition, the pixels of the backlight unit 40 are individually controlled on / off and light emission intensity by driving electrodes arranged in a matrix form, for example, scan electrodes and data electrodes positioned in directions perpendicular to each other.

In this embodiment, one pixel of the backlight unit 40 is formed of a field emission array (FEA) type electron emission device.

The FEA type electron emission device includes a scan electrode and a data electrode, an electron emission part and a fluorescent layer electrically connected to any one of the scan electrode and the data electrode. The electron emission part may be made of a material having a low work function or a high aspect ratio, for example, a carbon-based material or a nanometer (nm) size material.

The FEA type electron emitting device forms an electric field around the electron emitting part by using the voltage difference between the scan electrode and the data electrode to emit electrons therefrom, and excites the fluorescent layer with the emitted electrons to display visible light having an intensity corresponding to the electron beam emission amount. Release.

FIG. 2 is a partially cutaway perspective view of the liquid crystal panel assembly shown in FIG. 1.

Referring to the drawings, the liquid crystal panel assembly 10 includes a transparent first substrate 12 and a second substrate 14 disposed opposite to each other, and a liquid crystal injected between the first substrate 12 and the second substrate 14. A layer 16, a common electrode 18 located on an inner surface of the first substrate 12, pixel electrodes 20 and switching elements 22 located on an inner surface of the second substrate 14. do. Sealing members (not shown) are positioned at edges of the first substrate 12 and the second substrate 14.

The first substrate 12 is the front substrate of the liquid crystal panel assembly 10, and the second substrate 14 is the rear substrate of the liquid crystal panel assembly 10. On the outer surface of the first substrate 12 and the second substrate 14, a pair of polarizing plates 24, 26 whose polarization axes are perpendicular to each other are positioned. The inner surface of the first substrate 12 on which the common electrode 18 is located and the inner surface of the second substrate 14 on which the pixel electrodes 20 and the switching elements 22 are positioned are covered with the alignment layer 28. .

A plurality of gate lines 30 transmitting a gate signal and a plurality of data lines 32 transmitting a data signal are formed on an inner surface of the second substrate 14. The gate lines 30 are located next to each other along the row direction, and the data lines 32 are located next to each other along the column direction.

One pixel electrode 20 is positioned for each sub-pixel, and each sub-pixel includes a switching element 22 connected to the gate line 30 and a data line 32, and a liquid crystal connected to the switching element 22. Capacitor Clc (not shown) and sustain capacitor Cst (not shown) are formed. Holding capacitor Cst can be omitted as needed.

The switching element 22 may be formed of a thin film transistor, the control terminal and the input terminal of which are connected to the gate line 30 and the data line 32, respectively, and the output terminal of which is connected to the liquid crystal capacitor Clc.

The color filter 34 is disposed between the first substrate 12 and the common electrode 18. The color filter 34 is composed of red, green, and blue filters corresponding to one sub-pixel, and three sub-pixels in which three filters of red, green, and blue are located constitute one pixel.

When the thin film transistor, which is the switching element 22, is turned on in the liquid crystal panel assembly 10 having the above-described configuration, an electric field is formed between the pixel electrode 20 and the common electrode 18. The twist angle of the liquid crystal molecules positioned in the liquid crystal layer 16 is changed by this electric field to control a light transmission amount for each sub-pixel, thereby implementing a predetermined color image.

A first embodiment of the backlight unit will be described with reference to FIGS. 3 and 4, and a second embodiment of the backlight unit will be described with reference to FIG. 5. In both embodiments, the backlight unit consists of an FEA type electron emission display panel including FEA type electron emission elements.

3 is a partial cutaway perspective view of a backlight unit according to a first exemplary embodiment of the present invention, and FIG. 4 is a partial cross-sectional view of the fourth substrate and the electron emission unit illustrated in FIG. 3.

Referring to the drawings, the backlight unit 40 includes a third substrate 42 and a fourth substrate 44 which are disposed to face each other at a predetermined interval. The sealing member 46 is disposed at the edge of the third substrate 42 and the fourth substrate 44 to bond the two substrates, and the internal space is evacuated with a vacuum of approximately 10-6 Torr, so that the third substrate 42 The fourth substrate 44 and the sealing member 46 constitute a vacuum container.

The third substrate 42 becomes the front substrate of the backlight unit 40 facing the liquid crystal panel assembly, and the fourth substrate 44 becomes the rear substrate of the backlight unit 40. One surface of the fourth substrate 44 facing the third substrate 42 is provided with an electron emission unit 48 for electron emission, and one surface of the third substrate 42 facing the fourth substrate 44 emits light. Unit 50 is provided.

First, the electron emission unit 48 will be described. The electron emission unit 48 may include the cathode electrodes 52 formed in a stripe pattern along one direction of the fourth substrate 44 and the insulating layer 54. The gate electrodes 56 are formed in a stripe pattern along a direction orthogonal to the cathode electrode 52, and the electron emission units 58 electrically connected to the cathode electrode 52.

The gate electrodes 56 may be arranged side by side in the row direction of the fourth substrate 44, and may function as scan electrodes by applying a scan driving voltage. The cathode electrodes 52 may be arranged side by side in the column direction of the fourth substrate 44, and may function as a data electrode by receiving a data driving voltage.

Electron emitters 58 are formed in the cathode electrode 52 at each intersection of the cathode electrode 52 and the gate electrode 56. Openings 541 and 561 corresponding to the electron emission portions 58 are formed in the insulating layer 54 and the gate electrodes 56 to expose the electron emission portions 58 on the fourth substrate 44. In this embodiment, the intersection area of the cathode electrode 52 and the gate electrode 56 corresponds to one pixel area of the backlight unit 40.

The electron emission unit 58 is made of materials that emit electrons when an electric field is applied in a vacuum, such as a carbon-based material or a nanometer (nm) size material. The electron emission unit 58 may include, for example, carbon nanotubes, graphite, graphite nanofibers, diamonds, diamond-like carbons, C60, silicon nanowires, or a combination thereof. Growth, chemical vapor deposition or sputtering, and the like.

On the other hand, the electron emission portion may be formed of a tip structure having a pointed tip mainly made of molybdenum (Mo) or silicon (Si).

Next, the light emitting unit 50 provided on the third substrate 42 includes a fluorescent layer 60 and an anode electrode 62 positioned on one surface of the fluorescent layer 60. The fluorescent layer 60 may be formed of a white fluorescent layer or a combination of red, green, and blue fluorescent layers. In the figure, the first case is illustrated.

The white fluorescent layer may be formed on the entirety of the third substrate 42 or may be divided and positioned in a predetermined pattern so that one white fluorescent layer is positioned in each pixel area. The red, green, and blue fluorescent layers may be divided and positioned in a predetermined pattern in one pixel area.

The anode electrode 62 may be formed of a metal film such as aluminum (Al) covering the surface of the fluorescent layer 60. The anode electrode 62 is an acceleration electrode for attracting an electron beam, and is applied with a high voltage (a positive DC voltage of approximately several thousand volts) to maintain the fluorescent layer 60 in a high potential state, and among the visible light emitted from the fluorescent layer 60. The visible light emitted toward the fourth substrate 44 is reflected toward the third substrate 42 to increase the brightness of the screen.

In the above-described configuration, the FEA type electron emission device includes a cathode electrode 52, a gate electrode 56, electron emission portions 58, and a corresponding fluorescent layer 60 constituting one pixel.

In the above configuration, when a predetermined driving voltage is applied to the cathode electrodes 52 and the gate electrodes 56, an electric field is formed around the electron emission section 58 in the pixel region in which the voltage difference between the two electrodes is greater than or equal to the threshold. Electrons are emitted. The emitted electrons are attracted by the high voltage applied to the anode electrode 62 and collide with the corresponding fluorescent layer 60 to emit light. The emission intensity of the pixel-specific fluorescent layer 60 corresponds to the electron beam emission amount of the pixel.

5 is a partial plan view of the electron emission unit 48 'of the backlight unit according to the second embodiment of the present invention.

Referring to the drawings, in this embodiment, two or more intersection regions of the cathode electrode 52 'and the gate electrode 56' are combined to form one pixel region A. Referring to FIG. In this case, when two or more cathode electrodes 52 'and two or more gate electrodes 56' are combined to form one pixel region A, the two or more cathode electrodes 52 'are formed. Electrically connected to each other to receive the same driving voltage, two or more gate electrodes 56 'are also electrically connected to each other to receive the same driving voltage.

To this end, the two or more cathode electrodes 52 ′ and the two or more gate electrodes 56 ′ extend to the edge of the fourth substrate to form a connection member such as a flexible printed circuit board (FPCB). Ends (not shown) may be connected to each other.

In the drawing, as an example, nine crossing regions where three cathode electrodes 52 'and three gate electrodes 56' intersect form one pixel region A is illustrated.

In both the back light unit of the first embodiment and the back light unit of the second embodiment, the compression force applied to the vacuum container is supported between the third substrate 42 and the fourth substrate 44 and the distance between the two substrates is maintained. Spacers 64 (see Fig. 4) are arranged to keep the constant. The spacers 64 are preferably located outside the pixel area, not in the center of the pixel area.

In addition, if necessary, the third substrate 42 itself, which is a front substrate, may have a light diffusing function to function as a diffusion plate, and as shown in FIG. 6, an outer surface of the third substrate 42 facing the liquid crystal panel assembly. A diffuser plate 66 having a light diffusing function may be located in the.

As described above, the liquid crystal display 100 of the present exemplary embodiment uses a kind of low resolution display panel having a smaller number of pixels than the liquid crystal panel assembly 10 as the backlight unit 40. The backlight unit 40 is driven through a passive matrix method using scan electrodes and data electrodes, and provides light of different intensities to pixels of the liquid crystal panel assembly 10 corresponding to each pixel. .

The following table tests the display quality, the manufacturing cost of the driving circuit portion, the ease of manufacture, etc. while changing the number of pixels of the backlight unit 40 for the liquid crystal panel assembly 10 having an arbitrary resolution, and is derived according to the result. The optimal number of pixels of the backlight unit 40 for each resolution of the liquid crystal panel assembly 10 is shown.

Based on the above results, it can be seen that (liquid crystal panel assembly pixel number) / (backlight unit pixel number) is preferably in the range of 240 to 5,852. If the value exceeds 5,852, the effect of improving the dynamic contrast ratio by the backlight unit is insufficient, and if the value is less than 240, the manufacturing and driving of the backlight unit becomes difficult, thereby increasing the manufacturing cost.

In addition, in the present embodiment, one pixel of the backlight unit 40 may be formed to have a size of 2 to 50 mm along the row direction and / or the column direction. If the pixel size in the row direction and / or column direction is less than 2 mm, the backlight unit 40 has a considerable number of pixels, which makes it difficult to process the circuit signal, and the pixel size in the row direction and / or column direction On the contrary, if the amount exceeds 50 mm, the backlight unit 40 has a too small number of pixels, and the image quality improvement effect of the backlight unit 40 is insufficient.

As described above, the liquid crystal display device 100 according to the present embodiment uses the backlight unit 40 having the above-described configuration, and thus, a conventional cold cathode fluorescent lamp (hereinafter referred to as 'CCFL') and a light emitting diode (hereinafter referred to as 'LED'). Compared with the backlight unit of the type, it has the following advantages.

Since the backlight unit 40 of the present embodiment is a surface light source, it does not require a plurality of optical members used for the CCFL type backlight unit and the LED type backlight unit. Therefore, in the backlight unit 40 of the present embodiment, almost no light loss occurs while passing through the optical member, and the light unit 40 does not have to emit light of excessive intensity in consideration of the light loss. Efficiency can be obtained.

In addition, the backlight unit 40 of the present embodiment has a lower power consumption than the CCFL type back light unit, and can reduce the cost by not using the optical member. Low cost In addition, the backlight unit 40 of the present embodiment can be easily applied to a large liquid crystal display device of 30 inches or more because it is easy to enlarge the size.

7 is a block diagram illustrating a display device according to a third exemplary embodiment of the present invention. The display device according to the exemplary embodiment of the present invention is a light receiving element and includes a liquid crystal panel assembly using the liquid crystal element. However, the present invention is not limited thereto.

As shown in FIG. 7, the display device according to the third exemplary embodiment of the present invention includes a liquid crystal panel assembly 10, a gate driver 102 and a data driver 104 connected to the liquid crystal panel assembly 10, and data. The gray voltage generator 106 connected to the driver 104, the backlight unit 40 ′, and a signal controller 108 controlling them are included.

The liquid crystal panel assembly 10 includes a plurality of signal lines G1 -Gn and D1-Dm as viewed in an equivalent circuit, and a plurality of pixels PX connected to the signal lines and arranged in a substantially matrix form. do. The signal lines G1 -Gn and D1 -Dm include a plurality of gate lines G1 -Gn for transmitting a gate signal and a plurality of data lines D1 -Dm for transmitting a data signal.

Connected to each pixel PX, for example, the i-th (i = 1,2, ... n) gate line Gi and the j-th (j = 1,2, ... m) data line Dj The pixel 11 includes a switching element Q connected to signal lines Gi and Dj, a liquid crystal capacitor Clc, and a storage capacitor Cst connected thereto. Holding capacitor Cst can be omitted as needed.

The switching element Q is a three-terminal element such as a thin film transistor provided on a lower substrate (not shown), the control terminal of which is connected to the gate line Gi, and the input terminal of which is connected to the data line Dj. The output terminal is connected to the liquid crystal capacitor Clc and the storage capacitor Cst.

The gray voltage generator 106 generates two sets of gray voltages (or a set of reference gray voltages) related to the transmittance of the pixel PX. One of the two sets has a positive value for the common voltage Vcom, and the other set has a negative value.

The gate driver 102 is connected to the gate lines G1 -Gn of the liquid crystal panel assembly 10 to receive a gate signal formed of a combination of the gate on voltage Von and the gate off voltage Voff. To apply.

The data driver 104 is connected to the data lines D1-Dm of the liquid crystal panel assembly 10, selects a gray voltage from the gray voltage generator 106, and uses the data driver 104 as a data signal to the data lines D1-Dm. Is authorized. However, when the gray voltage generator 106 provides only a predetermined number of reference gray voltages instead of providing all of the voltages for all grays, the data driver 104 divides the reference gray voltages and thus the gray voltages for all grays. Generate and select the data signal from it.

The signal controller 108 controls the gate driver 102, the data driver 104, the backlight unit controller 110, and the like. The signal controller 108 receives an input image signal R, G, B and an input control signal for controlling the display thereof from an external graphic controller (not shown).

The input image signals R, G, and B contain luminance information of each pixel PX, and luminance has a predetermined number, for example, 1024 (= 2 ¹⁰ ), 256 (= 2 ⁸ ), or 64 ( = 2 ⁶ ) Gray scales. Examples of the input control signal include a vertical sync signal Vsync, a horizontal sync signal Hsync, a main clock MCLK, and a data enable signal DE.

The signal controller 108 appropriately processes the input image signals R, G, and B based on the input image signals R, G, and B and the input control signals according to the operating conditions of the liquid crystal panel assembly 10, and controls the gate. After generating the signal CONT1 and the data control signal CONT2, the gate control signal CONT1 is sent to the gate driver 102, and the data control signal CONT2 and the processed image signal DATA are transferred to the data driver 104). In addition, the signal controller 108 transmits the gate control signal CONT1, the data control signal CONT2, and the processed image signal DATA to the backlight unit controller 110.

The backlight unit 40 ′ includes a backlight unit controller 110, a column driver 112, a scan driver 114, and a display unit 116.

The column driver 112 is connected to the plurality of column lines C1-Cq, and each backlight unit pixel EPX11-EPXpq corresponds to itself according to the emission control signal CC and the emission signal CLS. Control is made to emit light corresponding to the gray scale of the liquid crystal pixel EX. The column driver 112 generates a plurality of light emission data signals according to the light emission signal CLS and transmits the plurality of light emission data signals to the plurality of column lines C1-Cq according to the light emission control signal CC. That is, the backlight unit pixels EPX11 to EPXpq may emit light at a predetermined gray scale in accordance with the display of the image on the plurality of liquid crystal pixels EX corresponding to one backlight unit pixel.

The scan driver 114 is connected to the plurality of scan lines S1-Sp and each of the backlight unit pixels EPX11-EPXpq corresponds to the plurality of liquid crystal pixels EX according to the scan driving control signal CS. Transmits a scanning signal to emit light in synchronization with

The display unit 116 includes a plurality of scan lines S1 -Sp for transmitting scan signals, a plurality of column lines C1-Cq for transferring column signals, and a plurality of backlight unit pixels EPX11-EPXpq. . Each of the plurality of backlight unit pixels EPX11-EPXpq is positioned in a region defined by the scan lines S1 -Sp and the column lines C1 -Cq that cross the scan lines. The scan lines S1-Sp are connected to the scan driver 114, and the column lines C1 -Cq are connected to the column driver 112. The scan driver 114 and the column driver 112 are connected to the backlight unit controller 110 to operate according to the control signal of the backlight unit controller 110.

The plurality of scan lines S1 -Sp are the scan electrodes of the above-described backlight unit 40 ', the column lines C1-Cq are the data electrodes, and the plurality of backlight unit pixels EPX11-EPXpq are It consists of an FEA type electron emission element.

The backlight unit controller 110 uses the image signals DATA of the plurality of liquid crystal pixels PX corresponding to each of the backlight unit pixels EPX11-EPXpq, respectively, to the pixels EPX of each backlight unit. The highest gray level is detected among the corresponding plurality of pixels PX, and a first gray level of each backlight unit pixel EPX11-EPXpq corresponding to the detected gray level is determined. In this case, when the pixel of the backlight unit is located at the outermost portion, the backlight unit controller 110 changes the gray scale value to compensate for the luminance lost in the backlight unit pixel located at the outermost position. In detail, the backlight unit controller 110 applies the compensation grayscale to change the first grayscale of each of the backlight unit pixels positioned at the outermost to the second grayscale. In this case, the compensation gradation means a gradation determined corresponding to the lost luminance to compensate for the luminance lost in the backlight unit pixel located at the outermost, and may have a different value according to the user's setting. In addition, the backlight unit controller 110 generates a light emission signal CLS corresponding to the first gray level and the second gray level, and transmits the generated light signal CLS to the column driver 112. The light emission signal CLS according to the embodiment of the present invention may be 6-bit or more digital data. Specifically, the digital data corresponding to the first grayscale is set as the first digital data, and the digital data corresponding to the second grayscale is set as the second digital data. Then, the column driver 112 generates a light emitting data signal according to the first digital data and transmits the light emitting data signal to a backlight unit pixel located in an area except the outermost, and generates a light emitting data signal according to the second digital data to the outermost. Transfer to the backlight unit pixels located at. In addition, the backlight unit controller 110 generates the scan driving control signal CS using the gate control signal CONT1. The backlight unit controller 110 generates the emission control signal CC using the data control signal CONT2 and transmits the emission control signal CC to the column driver 112.

Hereinafter, a method of compensating for luminance lost in a plurality of backlight unit pixels positioned at the outermost sides according to an exemplary embodiment of the present invention will be described in detail.

The backlight unit controller 110 detects the highest gray level among the plurality of pixels PX corresponding to each of the plurality of backlight unit pixels EPX11-EPXpq included in the scan lines S1 -Sp to the first gray level. Decide In addition, the backlight unit controller 110 applies the compensation grayscale to change the first grayscale of each of the backlight unit pixels positioned at the outermost to the second grayscale, and change the first grayscale and the second grayscale to the first and the second grayscales. 2 Convert to digital data. In addition, the backlight unit controller 110 transmits a scan driving control signal CS to the scan driver 114 of the backlight unit 40 ', and emits a light emission control signal CC and a light emitting signal to the column driver 112. Pass (CLS). Then, the scan driver 114 sequentially transmits the plurality of scan signals to the plurality of scan lines S1-Sp according to the scan driving control signal CS.

In detail, the scan driver 114 transmits a scan signal to the scan line S1 according to the scan drive control signal CS. In this case, the plurality of backlight unit pixels EPX11-EPX1q connected to the scan line S1 are positioned at the outermost corners. The column driver 112 generates a plurality of light emitting data signals according to the second digital data, and is positioned at the intersection of the scan line S1 and the plurality of column lines C1-Cq according to the light emission control signal CC. It transfers to the plurality of backlight unit pixels EPX11-EPX1q. Then, each of the light emission data signals according to the second digital data to which the compensation gray is applied is transmitted to the plurality of backlight unit pixels EPX11 to EPX1q located at the outermost sides connected to the scan line S1, thereby compensating for the lost luminance. Can be. According to an exemplary embodiment of the present invention, the scan line S1 and the plurality of backlight unit pixels EPX11-EPX1q and EPXp1-EPX1pq connected to the scan line Sp are positioned at the outermost side, and the scan line Sp is the same method. Loss of luminance of the backlight unit pixel positioned at the outermost portion may be compensated for by using.

In addition, the scan driver 114 transmits a scan signal to the scan line S2 according to the scan drive control signal CS. In this case, the plurality of backlight unit pixels EPX21-EPX2q connected to the scan line S2 include two backlight unit pixels EPX21 and EPX2q positioned at the outermost sides. The column driver 112 generates a plurality of emission data signals according to the emission signal CLS. In this case, the emission signal CLS may include second digital data corresponding to the two outermost backlight unit pixels EPX21 and EPX2q and a plurality of remaining backlight unit pixels EPX22 to EPX2q-1. Contains 1 digital data. In detail, the column driver 112 is disposed at the pixels EPX21 and EPX2q positioned at the intersections of the scan lines S2 and the column lines C1 and Cq positioned at the outermost of the column lines C1-Cq. The plurality of light emitting data signals generated according to the second digital data are transferred. In addition, the column driver 112 may include a plurality of first digital units in the plurality of backlight unit pixels EPX22-EPX2q-1 positioned at the intersections of the scan line S2 and the column lines C2-Cq-1 except the outermost part. The light emitting data signal generated according to the data is transferred. Then, the respective luminance data signals according to the second digital data to which the compensation gray level is applied are transmitted to the two outermost unit units EPX21 and EPX2q located at the outermost sides connected to the scan line S2, thereby compensating for the lost luminance. Can be. Lossed luminance of each of the plurality of backlight unit pixels located at the outermost part connected to the scan line S3-Sp-1 according to the embodiment of the present invention is also the same using the same method. To compensate.

8A and 8B specifically illustrate driving waveforms of the backlight unit 40 'according to the third example of the present invention. It is assumed that the backlight unit 40 ′ according to the third embodiment of the present invention transfers the first light emission data on voltage Von having the same level to the plurality of column lines C1-Cq for convenience of description. do.

The driving waveform shown in FIG. 8A is transmitted to the plurality of backlight unit pixels EPX11-EPXpq positioned in the region except the outermost portion. Specifically, the scan-on voltage Vs is applied to any one of the plurality of scan lines S1 -Sp in the period T11, and the first emission data on voltage Von is applied to each of the column lines except the outermost part. Is approved. Then, the plurality of backlight unit pixels positioned in the region excluding the outermost light emit light with luminance corresponding to the voltage difference Vs-Von applied to the scan line Si and the column line. Thereafter, the scan on voltage Vs is maintained in the scan line Si in the T12 section, and the light emission data off voltage Voff is applied to each of the column lines except the outermost part. As a result, the plurality of backlight unit pixels positioned in the region excluding the outermost angle decreases the voltage difference Vs-Voff applied to the scan line Si and the column line and does not emit light. The driving waveform according to the embodiment of the present invention can express appropriate gray scale by changing the pulse width of the T11 section and the T12 section.

Meanwhile, the driving waveform as shown in FIG. 8B is transmitted to the plurality of backlight unit pixels positioned at the outermost side to compensate for the lost luminance. Specifically, the scan-on voltage Vs is applied to any one of the plurality of scan lines S1 -Sp in the period T21, and each of the column lines positioned at the outermost part of the plurality of column lines C1 -Cq is provided. The second emission data on voltage V1 to which the voltage Vt corresponding to the compensation gray level is applied is applied to the first emission data on voltage Von. Then, the plurality of backlight unit pixels positioned at the outermost portion emit light with luminance corresponding to the voltage difference Vs-V1 applied to the scan line Si and the column line positioned at the outermost portion, and at this time, the plurality of backlight unit pixels The lost luminance is compensated for the pixel EPX. Thereafter, the scan-on voltage Vs is maintained in the scan line Si in the T22 section, and the light emission data off voltage Voff is applied to the column line positioned at the outermost portion. As a result, the plurality of backlight unit pixels positioned at the outermost portions of the plurality of backlight unit pixels do not emit light because the voltage difference Vs-Voff applied to the scan line Si and the column line is reduced. The driving waveform according to the exemplary embodiment of the present invention may express appropriate gray scale by changing the pulse width of the T21 section and the T22 section.

As described above, the plurality of backlight unit pixels positioned at the outermost sides may emit light corresponding to the plurality of emission data signals to which the compensation gray levels are applied, thereby compensating for the luminance lost in the outermost pixels.

The embodiment using a display device using a liquid crystal panel assembly has been described so far, but the present invention is not limited thereto. As a display device other than self-luminous, it is applicable to both display devices that receive images from a backlight unit and display an image.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the range of.

According to an aspect of the present invention, a display device and a method of driving the same may compensate for lost luminance of a plurality of backlight unit pixels positioned at the outermost sides by using a compensation gray scale, thereby preventing a decrease in luminance.

Claims (7)

A panel assembly including a plurality of gate lines for transmitting a plurality of gate signals, a plurality of data lines for transmitting a plurality of data signals, and a plurality of pixels defined by the plurality of gate lines and the plurality of data lines, and A backlight having a plurality of scan lines for transmitting a plurality of scan signals, a plurality of column lines for transmitting a plurality of light emitting data signals, and a plurality of backlight unit pixels defined by the plurality of scan lines and the plurality of column lines. Unit, The backlight unit, The first gray level of the first backlight unit pixel is determined according to the gray level of the plurality of pixels corresponding to the first backlight unit pixel positioned at the outermost part of the plurality of backlight unit pixels, and the first back The display device changes the first gray level to the second gray level by using a compensation gray level corresponding to the luminance lost in the light unit pixel. The method of claim 1, The backlight unit, A gray level corresponding to the highest gray level among the plurality of pixels corresponding to the first backlight unit pixel is determined as a first gray level of the first backlight unit pixel, And a display device configured to compensate for luminance loss occurring in the first backlight unit pixel by using the second gray level to which the compensation gray level is applied to the first gray level. The method of claim 2, The backlight unit, Transmits a light emitting data signal generated according to second digital data corresponding to the second grayscale to the first backlight unit pixel, And a display device for transmitting the light emission data signal generated according to the first digital data corresponding to the first grayscale to the backlight unit pixels except for the first backlight unit pixel. A method of driving a display device comprising a panel assembly having a plurality of pixels and a backlight unit having a plurality of backlight unit pixels, a) determining a first gray level of a first backlight unit pixel located at an outermost position among the plurality of backlight unit pixels, and b) changing the first gradation to a second gradation using a compensation gradation corresponding to the luminance lost in the first backlight unit pixel. The method of claim 4, wherein Step b), And a method of compensating for a luminance loss generated in the first backlight unit pixel by using the second gray level. The method of claim 4, wherein Step a) is And determining a first gray level of the first backlight unit pixel according to the gray levels of the plurality of pixels corresponding to the pixels of the first backlight unit. The method of claim 4, wherein Step b), Transmitting a light emitting data signal generated according to second digital data corresponding to the second grayscale to the first backlight unit pixel, and And transmitting the light emission data signal generated according to the first digital data corresponding to the first grayscale to the backlight unit pixels except for the first backlight unit pixel.

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