KR20080049898A - Display apparatus and driving method of the same - Google Patents

Abstract

A display device and a driving method thereof are provided to implement a sequential driving mode of a new concept, for combining temporal color mixture and spatial color mixture modes, by forming a color filter in a partial pixel of a display panel and sequentially driving LEDs(Light Emitting Diode), thereby preventing color mixture of a color image and improving a contrast ratio. A display panel includes one color filter(522) of RGB(Red, Green and Blue) color filters. A light source unit(300) includes RGB light sources(RL,GL,BL) for emitting different light according to each field. The display panel comprises the following parts. In a first substrate, pixel units defined by plural gate lines and data lines are formed. A second substrate faces the first substrate. In a second substrate, the one color filter is formed in correspondence with a partial area of each pixel unit. An LC(Liquid Crystal) layer is interposed between the first and second substrates.

Description

DISPLAY APPARATUS AND DRIVING METHOD OF THE SAME}

1 is an exploded perspective view illustrating a display device according to an exemplary embodiment of the present invention.

FIG. 2 is a plan view illustrating the display panel of FIG. 1.

3 is a perspective view illustrating a schematic structure of the display device illustrated in FIG. 1.

4 is a graph illustrating color coordinates of the light source unit illustrated in FIG. 1.

FIG. 5 is a graph illustrating color coordinate movement according to a wavelength change of the light source unit illustrated in FIG. 1.

FIG. 6 is a timing diagram schematically illustrating a method of driving the light source unit illustrated in FIG. 1.

FIG. 7 is a timing diagram illustrating contrast ratios when the display device illustrated in FIG. 1 is sequentially driven.

<Description of the symbols for the main parts of the drawings>

100: storage container 200: drive substrate

300: light source unit 400: backlight assembly

500: display panel 510: first substrate

520: second substrate 522: color filter

600: display device

RL, GL, BL: red light source, green light source, blue light source

P_R, P_G, P_B: red pixel, green pixel, blue pixel

R_F, G_F, B_F, W_F: Red Field, Green Field, Blue Field, White Field

The present invention relates to a display device and a driving method thereof, and more particularly, to a display device of a sequential driving method and a driving method thereof.

In general, a liquid crystal display device is a flat panel display that displays an image by using the light transmittance of the liquid crystal. The liquid crystal display includes a display panel for displaying an image using light and a backlight assembly for supplying light to the display panel.

Recently, a liquid crystal display device in which a color filter of a display panel is removed by using a light emitting diode (LED) with low power consumption and excellent light emission efficiency as a light source has been developed. Conventional liquid crystal displays use color filters to express colors by using spatial blending, while color filter-less (CFL) liquid crystal displays emit red, green, and blue light emitting diodes sequentially. Colors are expressed through mixed colors.

However, when the red, green, and blue light emitting diodes are sequentially driven on a line-by-line basis, color mixing occurs between the lines, thereby reducing color reproduction.

On the other hand, the backlight assembly to which the light emitting diode is applied is known to be excellent in color reproducibility by covering a large color coordinate. However, the large area of the color reproduction area does not determine the excellent screen display quality.

The recently developed Adobe RGB color space has a wide color reproduction area, and particularly, excellent color reproduction in the blue and green areas. When using the Adobe RGB color space, a liquid crystal display must support the wide color reproduction area of Adobe RGB to realize accurate color images. However, although the color coordinates of the liquid crystal display device using the light emitting diode have excellent color reproducibility, there is a problem in that they do not completely cover the Adobe RGB color space.

Accordingly, the technical problem of the present invention is to solve such a conventional problem, and an object of the present invention is to provide a display device for improving color reproducibility and implementing an optimal color reproduction area in a sequential driving method.

Another object of the present invention is to provide a method of driving the above-described display device.

In order to realize the above object of the present invention, a display device according to an embodiment displays a color image by time-dividing a unit frame into a plurality of fields displaying different colors, and displays a red color filter, a green color filter, and a blue color. The display panel may include a display panel including any one of the filters, and a light source unit having red, green, and blue light sources that emit light of different colors corresponding to each field.

In accordance with another aspect of the present invention, there is provided a method of driving a display device, which time-divides a unit frame into a plurality of fields displaying different colors to display a color image, and includes a blue color filter. A method of driving a display device, the method comprising: displaying a red image using red light emitted by driving a red light source, displaying a green image using green light emitted by driving a green light source, and red, green, and blue And driving the light source to pass the first white light emitted through the blue color filter to display a blue image. The method may further include displaying a white image by using the second white light emitted by driving the red, green, and blue light sources.

According to such a display device and a driving method thereof, it is possible to prevent color deterioration due to color mixing and to implement an optimal color reproduction area that supports the Adobe RGB color space.

Hereinafter, with reference to the accompanying drawings, it will be described in detail the present invention.

1 is an exploded perspective view illustrating a display device according to an exemplary embodiment of the present invention. FIG. 2 is a plan view illustrating the display panel of FIG. 1.

1 and 2, the display device 600 includes a display panel 500 and a backlight assembly 400. The display device 600 is time-division driven by a plurality of fields in which one frame displays different colors to display a color image.

The display panel 500 is disposed above the backlight assembly 400 and displays an image using light supplied from the backlight assembly 400. The display panel 500 includes a first substrate 510, a second substrate 520 facing the first substrate 510, and a liquid crystal layer interposed between the first substrate 510 and the second substrate 520. Not shown) and a driving circuit unit 540 for driving the first substrate 510.

In the present invention, the display panel 500 includes one color filter 522 of a red color filter, a green color filter, and a blue color filter.

In detail, the first substrate 510 includes gate lines GL and data lines DL that intersect the gate lines GL, and the first substrate 510 is formed by the gate lines GL and the data lines DL. A plurality of pixel units PA is defined. Each pixel unit PA includes a plurality of subpixels P. Each subpixel P is provided with a switching element TFT connected to the gate line GL and the data line DL, and a pixel electrode PE connected to the switching element TFT.

The second substrate 520 is disposed to face the first substrate 510. The second substrate 520 is formed to correspond to the gate lines GL and the data lines DL, and includes a light blocking pattern (not shown) that partitions the pixel units PA, and some sub-pixels P of the pixel units PA. ) Includes a color filter 522 and a common electrode (not shown) facing the pixel electrode PE.

By combining the first and second substrates 510 and 520, the display panel 500 is divided into a plurality of pixel units PA. Each of the pixel units PA may include a plurality of subpixels P. The pixel unit PA may include, for example, a red pixel displaying a red image, a green pixel displaying a green image, and a blue pixel displaying a blue image.

In one embodiment of the present invention, the color filter 522 may not be formed in the entire area of the pixel portion PA, but may be formed in some sub-pixels P. FIG. For example, the color filter 522 may be formed in any one of the red, green, and blue pixels.

The liquid crystal layer is interposed between the first substrate 510 and the second substrate 520. In the liquid crystal layer, an arrangement of liquid crystals is changed by an electric field formed between the pixel electrode PE and the common electrode. According to the arrangement change of the liquid crystal molecules, an image may be displayed by adjusting the transmittance of light supplied from the backlight assembly 400.

The driving circuit unit 540 includes a data printed circuit board 548 for supplying a data driving signal to the display panel 500, a gate printed circuit board 544 for supplying a gate driving signal to the display panel 500, and a data printed circuit board. The data driving circuit film 546 connects 548 to the display panel 500, and the gate driving circuit film 542 connects the gate printed circuit board 544 to the display panel 500.

The backlight assembly 400 may include the storage container 100, the driving substrates 200, and the light source units 300.

The storage container 100 includes a bottom portion 110 and side portions 120 extending from an edge of the bottom portion 110 to form a storage space. The driving substrate 200 and the light source unit 300 are accommodated in the accommodation space. The storage container 100 is made of, for example, a metal having excellent strength and low deformation.

The light source units 300 are disposed on the driving substrates 200. For example, the driving substrates 200 may extend long in the longitudinal direction of the bottom portion 110. The driving substrates 200 are electrically connected to an external power supply device (not shown) to supply power to the light source unit 300 and include signal wiring for supplying power.

A plurality of light source units 300 are disposed on the driving substrates 200. The light source units 300 may be arranged in a line along the arrangement direction of the gate lines GL of the display panel 500. The light source units 300 emit light of different colors corresponding to each field. For example, the light source units 300 may sequentially generate red light, green light, blue light, and white light corresponding to each field during one frame. The number of light source units 300 may be variously modified according to the size of the display panel 500 or the required luminance.

For example, the light source units 300 are spaced apart in a row on the driving substrate 200 to form a plurality of light source bars LB. From the first light source bar LB to the last light source bar LB, each of the light source bars LB sequentially emits red light, green light and blue light.

As such, the light source units 300 sequentially emit light of different colors, and the display panel 500 includes any one of a red color filter, a green color filter, and a blue color filter. Can display an image using two methods, temporal mixing and spatial mixing.

3 is a perspective view illustrating a schematic structure of the display device illustrated in FIG. 1.

2 and 3, the light source units 300 emit light of different colors corresponding to each field during one frame. To this end, each light source unit 300 includes a red light source RL, a green light source GL, and a blue light source BL that emit light of different colors, and have a red light and a green color for a predetermined time with a time difference. The light and blue light are emitted sequentially. The red light source RL, the green light source GL, and the blue light source BL may be arranged in various forms such as a triangle or a rhombus.

For example, the light source units 300 may include a light emitting diode. That is, the light source units 300 may include a red light emitting diode, a green light emitting diode, and a blue light emitting diode.

The light source units 300 emit red light by driving the red light source RL, emit green light by driving the green light source GL, and emit blue light by driving the blue light source BL. In addition, the light source units 300 may simultaneously drive the red light source RL, the green light source GL, and the blue light source BL to emit white light.

Specifically, when the red light source RL is driven, the red light emitted from the light source unit 300 passes through the red pixel P_R and is emitted as red light as it is. When driving the green light source GL, the green light emitted from the light source unit 300 passes through the green pixel P_G and is emitted as green light as it is. When the blue light source BL is driven, the red, green, and blue light sources RL, GL, and BL are driven at the same time so that the white light emitted from the light source unit 300 passes through the blue pixel P_B to be changed into blue light. It is released. That is, the white light emitted from the light source units 300 may pass through the blue color filter 522 formed in the blue pixel P_B to display a blue image.

4 is a graph illustrating color coordinates of the light source unit illustrated in FIG. 1. FIG. 5 is a graph illustrating color coordinate movement according to a wavelength change of the light source unit illustrated in FIG. 1.

3 and 4, Adobe RGB is a practical RGB color coordinate introduced by Adobe Systems Inc. Adobe RGB has a wide color gamut from blue to green. For example, when Adobe RGB is used for image data, the display device 600 also needs to support a wide color reproduction area of Adobe RGB to implement accurate color images.

Ref is a graph showing color reproducibility of light emitted from the light source units 300. Ref doesn't cover Adobe RGB perfectly. The red and blue areas of Ref cover Adobe RGB, but the green areas do not cover Adobe RGB.

On the other hand, the LED scroll is data representing the color reproducibility when the light emitted from the light source units 300 is not affected by the color mixing. The red and blue areas of the LED scroll cover Adobe RGB, but the green areas do not cover Adobe RGB.

In contrast, the color sequential LCD (CSD) is data representing color reproducibility when the red, green, and blue light sources of the light source units 300 are sequentially driven. The blue region of the CSD satisfies Adobe RGB, but not the red region. This is because the color purity of red is degraded by color mixing between the light source bars LB during sequential driving. The blue areas of the CSD cover Adobe RGB, but the red and green areas do not cover Adobe RGB.

Meanwhile, in order to cover 100% of Adobe RGB, the wavelengths of the red, green, and blue light sources RL, GL, and BL may be adjusted. However, in general, when the display panel 500 includes a color filter, it is difficult to fully satisfy Adobe RGB due to the influence of the color filter. Because the transmission spectrum of the display device 600 is determined by the product of the transmission spectrum of the color filter and the light spectrum from the corresponding color light source, the emission spectrum of each of the red, green, and blue light sources RL, GL, and BL is emitted. This is because when the light passes through the color filter, the original color is distorted and emitted. Accordingly, by preventing the light from the light source units 300 from passing through the color filter, the red, green, and blue regions may be extended to the outermost in the color coordinates.

Compared with Adobe RGB, the blue region generally has room to spare, and the red and green regions need to be further extended to the outermost side. Accordingly, the display device 600 preferably includes a blue color filter 522 rather than a red and green color filter in order to satisfy Adobe RGB.

For example, the white light emitted from the light source units 300 may pass through the blue color filter 522 formed on the display panel 500 to display a blue image. As the light source units 300 that emit light of different colors corresponding to each field during one frame emit white light in an arbitrary field, the display device 600 is caused by color mixing in the backlight assembly 400. The fall of the color reproducibility can be prevented.

In addition, referring to FIG. 5, for example, the wavelength of light emitted from the light source units 300 may be changed so that the color coordinate region of the display device 600 covers Adobe RGB.

As in one embodiment of the present invention, by adjusting the wavelength of the blue light from the blue light source BL, it is possible to shift the green region of the color coordinate to a long wavelength range. As the wavelength of the blue light is increased, the color coordinate region may move so that the green region may cover the long wavelength region. In general, the wavelength band of the blue light emitted from the blue light source BL is about 450 to 460 nm, and the wavelength band of the emitted light may be adjusted by adjusting the component ratio of the composition compound. For example, the blue light source BL may emit light having a wavelength of about 445 to 455 nm, which is about 5 nm reduced from the wavelength band.

FIG. 6 is a timing diagram schematically illustrating a method of driving the light source unit illustrated in FIG. 1.

3 and 6, one frame (1 FRAME) of the display device 600 may be time-divided and driven into four fields R_F, G_F, B_F, and W_F. The display device 600 time-divides the unit frame into a red field (R_F) displaying red, a green field (G_F) displaying green, a blue field (B_F) displaying blue, and a white field (W_F) displaying white. To display a color image.

The light source units 300 emit light of different colors corresponding to each field. For example, the light source units 300 emit red light corresponding to the red field R_F, emit green light corresponding to the green field G_F, and first white light corresponding to the blue field B_F. And emit a second white light corresponding to the white field W_F. Meanwhile, the light emission order of the red light, the green light, and the blue light may be variously modified.

Specifically, first, the light source unit 300 emits red light by driving the red light source RL in the red field R_F. The red light passes through the red pixel P_R in which the color filter is not formed, and displays a red image. Next, the light source unit 300 emits green light by driving the green light source GL in the green field G_F. The green light passes through the green pixel P_G where the color filter is not formed to display a green image. Subsequently, the light source unit 300 drives the red, green, and blue light sources RL, GL, and BL in the blue field B_F to emit the first white light. The first white light passes through the blue pixel P_B on which the blue color filter 522 is formed to display a blue image. Finally, the light source unit 300 drives the red, green, and blue light sources BL in the white field W_F to emit the second white light. The second white light passes through the red and / or green pixels P_R and P_G where no color filter is formed to display a white image. As such, the light source units 300 of the present invention may be sequentially driven in the order of R_G_W_W.

As described above, in the blue field B_F displaying the same color as the color of the blue color filter 522 formed on the display panel 500, the first white light emitted from the light source units 300 is the blue color filter 522. ) Is converted into blue light and emitted. In the other fields R_F and G_F, the red and green light emitted from each of the red and green light sources RL and GL are emitted without passing through the blue color filter. That is, the red and green images are displayed using red and green light sequentially emitted without using the color filter, and the blue image is emitted through the blue color filter 522 of the blue pixel P_B. Is displayed using. Accordingly, the display device 600 may display a color image by combining spatial mixing and temporal mixing.

Alternatively, one frame of the display device 600 may be time-divided and driven into three fields R_F, G_F, and B_F. That is, the display device 600 may time-division a unit frame into a red field R_F displaying red, a green field G_F displaying green, and a blue field B_F displaying blue to display a color image. .

As described above, even if the number of fields in which the unit frame is time-divided varies, the backlight assembly may emit white light in any one of the red, green, and blue fields R_F, G_F, and B_F of the unit frame through the above-described method. Color mixing at 400 can be prevented.

FIG. 7 is a timing diagram illustrating contrast ratios when the display device illustrated in FIG. 1 is sequentially driven.

Referring to FIGS. 6 and 7, in general, in the display device 600 which is driven by a sequential driving method, a color break up (CBU) phenomenon in which colors of an image are separated into original colors may occur. . In order to eliminate the CBU phenomenon, the four-field driving method is more advantageous than the three-field driving method. Because, in general, the four field driving method is sequentially driven to R_G_B_W, and further includes the white field W_F as the last field, thereby eliminating color interference between the previous frame and the current frame. However, in the case of the four-field driving method, since the luminance of the white mode corresponds to only one field among the four fields, the contrast ratio (CR = W / B) of the display device 600 is reduced.

Meanwhile, in the sequential driving method, the luminance (Luminance, L) in the R_G_W_W method and the R_G_B_W method will be compared. The R_G_W_W method is a method in which the light source units 300 sequentially emit red light, green light, first white light, and second white light. In contrast, the R_G_B_W method is a method in which the light source units 300 sequentially emit red light, green light, blue light, and white light.

In the R_G_W_W scheme as in one embodiment of the present invention, the luminance of the white mode W1 is greater than that of the white mode W2 in the R_G_B_W scheme. This is because in the display device 600 sequentially driven at R_G_W_W, since the light source units 300 emit white light instead of blue light in the blue field B_F, the luminance in the white mode may be further increased. As described above, since white light emitted from the blue field B_F is emitted through the blue color filter 522 (see FIG. 3) as blue light, there is no problem in implementing a blue image. Accordingly, the display device 600 sequentially driven at R_G_W_W may improve contrast ratio.

For example, the R_G_W_W sequential driving method may be applied to the display device 600 including the display panel 500 in an OCB (Optically Compensated Birefringence) mode. Accordingly, the contrast ratio of the OCB mode display panel 500 with a large amount of leakage light can be improved.

As described above, as a color filter is formed on some pixels of the display panel and the LEDs are sequentially driven, a new concept of sequential driving method combining temporal color mixing and spatial color mixing can be implemented. Accordingly, color mixing of the color image can be prevented, and contrast ratio can be improved.

In addition, by changing the light wavelength band of the light emitting diode, it is possible to more fully cover the Adobe RGB color space. Accordingly, color reproducibility and display quality of the liquid crystal display device implemented in a sequential driving method can be improved.

Although described above with reference to the embodiments, those skilled in the art can be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below. I can understand.

Claims (7)

 A display apparatus for displaying a color image by time division of a unit frame into a plurality of fields displaying different colors. A display panel including any one of a red color filter, a green color filter, and a blue color filter; And And a light source unit having red, green, and blue light sources that emit light of different colors corresponding to each field. The display panel of claim 1, wherein the display panel A first substrate on which pixel portions defined by a plurality of gate lines and data lines are formed; A second substrate corresponding to the first substrate and having one of the color filters corresponding to a partial region of each pixel portion; And And a liquid crystal layer interposed between the first substrate and the second substrate. The display device of claim 2, wherein each of the pixel units includes a red pixel, a green pixel, and a blue pixel. And the color filter is formed at a position corresponding to the blue pixel. The display device of claim 1, wherein the blue light source emits light having a wavelength of 445 to 455 nm. A method of driving a display device including time-dividing a unit frame into a plurality of fields displaying different colors to display a color image, and including a blue color filter, Displaying a red image using the red light emitted by driving the red light source; Displaying a green image using the green light emitted by driving the green light source; And And displaying a blue image by passing the first white light emitted by driving the red, green, and blue light sources through the blue color filter. The method of claim 5, further comprising displaying a white image using the second white light emitted by driving the red, green, and blue light sources. The method of claim 6, wherein the second white light passes through a region where the blue color filter is not formed.

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