KR20050119437A - Liquid crystal display - Google Patents

Abstract

The present invention relates to a liquid crystal display device having a liquid crystal panel for forming an image, comprising: a reflecting portion spaced apart from a rear surface of the liquid crystal panel; At least one circuit board disposed between the liquid crystal panel and the reflector; A plurality of light emitting elements provided on the circuit board to irradiate light toward the reflecting portion; And a light diffusion unit disposed between the circuit board and the liquid crystal panel. As a result, the light emitted from the light source unit can be more effectively diffused to reach the liquid crystal panel. In particular, when LED is used as the light source, the thickness of the liquid crystal display device can be effectively secured by effectively securing the distance between the light source and the liquid crystal panel for color mixing. It is possible to provide a liquid crystal display device which can exhibit excellent optical characteristics without increasing or adding an additional optical system.

Description

Liquid crystal display

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having an improved structure so that light emitted from a light source unit can be more effectively diffused to reach a liquid crystal panel.

In general, a liquid crystal display (LCD) is a device for displaying a desired image by adjusting the light transmittance of liquid crystal cells arranged in a matrix form according to image signal information. The liquid crystal display device forms an image in the liquid crystal panel using light emitted from the backlight assembly.

In general, the backlight assembly includes a direct light source in which a light source is disposed on a rear surface of a liquid crystal panel so that light is directly transmitted to a rear surface of the liquid crystal panel, and a light guide plate is disposed on a rear surface of the liquid crystal panel, and a light source is disposed along at least one side of the light guide plate. The light guide plate is divided into an edge type transmitted through the liquid crystal panel.

The direct method is a method in which a light source is disposed on a rear surface of a liquid crystal panel to direct light to a liquid crystal panel through a light diffusion unit. The direct method is mainly used in large liquid crystal display devices that require high brightness due to the low light uniformity and durability but good light utilization efficiency compared to the edge method.

However, in the case of the direct method, in order for the light of the light source unit to be sufficiently diffused to reach the rear surface of the liquid crystal panel, the light source unit and the light diffusion unit and the light diffusion unit and the liquid crystal panel should be separated by a predetermined distance, respectively. Thus, there is a problem in that the overall thickness of the liquid crystal display becomes thick.

Recently, it is considered to use RGB LED as a light source as a method for improving the quality of moving picture reproduction. The light source color is mixed with each other to produce white light and supply it to the liquid crystal panel.

Therefore, it is required to secure a space for mixing the RGB monochromatic light emitted from each LED. However, the light emitted from the LED is very straight forward, so in order to mix it, it is necessary to secure the distance from the light source to the liquid crystal panel more than using a conventional surface light source, or to use a complicated optical path using an additional optical system. Since it is necessary to ensure the overall thickness of the liquid crystal display device has a problem that further increases.

Therefore, an object of the present invention, the light irradiated from the light source unit can be more effectively diffused to reach the liquid crystal panel, especially when using the LED as the light source, by effectively securing the distance between the light source and the liquid crystal panel for color mixing, The present invention provides a liquid crystal display device that can exhibit excellent optical characteristics without increasing the thickness of the liquid crystal display device or adding an additional optical system.

The above object is, according to the present invention, a liquid crystal display device having a liquid crystal panel for forming an image, comprising: a reflecting portion spaced apart from a rear surface of the liquid crystal panel; At least one circuit board disposed between the liquid crystal panel and the reflector; A plurality of light emitting elements provided on the circuit board to irradiate light toward the reflecting portion; And a light diffusing portion disposed between the circuit board and the liquid crystal panel.

Here, the light emitting device is preferably a light emitting diode (LED).

In addition, the reflector is preferably made of a material having a light diffusion.

In addition, it is preferable to further include an auxiliary light diffusing unit disposed between the plurality of light emitting elements and the reflecting unit, and the auxiliary light diffusing unit preferably includes a light guide plate.

The display device may further include at least one light emitting device disposed on the circuit board to irradiate light toward the liquid crystal panel.

In the above liquid crystal display device, it is preferable that at least one side of both surfaces of the circuit board is provided with an auxiliary reflecting unit.

Thus, the light irradiated from the light source unit can be effectively diffused to reach the liquid crystal panel, and in particular, in the case of using the LED as a light source, color mixing is also effective.

Hereinafter, a liquid crystal display according to a first exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

Prior to the description, in the various embodiments, components having the same configuration will be representatively described in the first embodiment using the same reference numerals, and in other embodiments, only the configuration different from the first embodiment will be described. do.

In addition, the liquid crystal display shown in the present specification will be schematically illustrated by highlighting the characteristics by using a direct method using a light emitting diode (LED) as a light source.

As shown in FIGS. 1 and 2, the liquid crystal display according to the first exemplary embodiment of the present invention includes a liquid crystal panel 10 for forming an image and a driver integrated circuit for driving the liquid crystal panel 10 (not shown). ), A mold frame 60 supporting the edge of the liquid crystal panel 10, a backlight assembly 3 for irradiating light to the rear surface of the liquid crystal panel 10, a backlight assembly 3, and a mold frame ( A bottom chassis 70 supporting the 60 and a top chassis 80 coupled to the bottom chassis 70 to cover the front surface of the liquid crystal panel 10 are included. In addition, a heat dissipation member (not shown) is attached to an outer rear surface of the bottom chassis 70 to easily dissipate heat generated from the backlight assembly 3 to the outside.

The liquid crystal panel 10 is injected between the thin film transistor substrate 11, the color filter substrate 12 attached to face the thin film transistor substrate 11, and the thin film transistor substrate 11 and the color filter substrate 12. It includes a liquid crystal (not shown). The liquid crystal (not shown) is injected between the thin film transistor substrate 11 and the color filter substrate 12 and then sealed. In addition, polarizers (not shown) are attached to the front surface of the color filter substrate 12 and the rear surface of the thin film transistor substrate 11 so as to cross-polarize each other. The liquid crystal panel 10 is arranged in a matrix form of the liquid crystal cells forming a pixel unit, and forms an image by adjusting the light transmittance of the liquid crystal cells according to the image signal information transmitted from the driver integrated circuit (not shown).

The mold frame 60 is formed along the edge of the liquid crystal panel 10 and has a substantially rectangular shape and supports the liquid crystal panel 10 spaced apart from the backlight assembly 3.

The backlight assembly 3 is disposed on the back of the liquid crystal panel 10 and the light diffuser 5 disposed on the back of the light diffuser 5 to the light through the light diffuser 5 to the liquid crystal panel 10. It includes a light source unit 40 for irradiating the reflection portion 50 provided on the inner bottom surface of the bottom chassis 70.

The light diffusing unit 5 is disposed between the light source unit 40 and the liquid crystal panel 10, and converts the light incident from the light source unit 40 into near plane light to irradiate the liquid crystal panel with the light guide plate 30 and the light guide plate 30. The optical sheet 20 is disposed on the front surface of the light guide plate 30 and diffuses light emitted from the light guide plate 30 to the liquid crystal panel 10.

The light guide plate 30 spreads the incident light to the uniform plane light by spreading the concentrated light inside the light guide plate 30 using the principle of total reflection. As the material of the light guide plate 30, PMMA (Polymethylmethacrylate) having high strength is not easily deformed or broken and has good transmittance.

The optical sheet 20 is a diffusion sheet that partially diffuses light emitted from the light guide plate 30 to the liquid crystal panel 10 to diffuse light so that spots do not occur in the liquid crystal panel 10, thereby further improving the uniformity of light. And a prism sheet 22 for improving the brightness by allowing the light passing through the diffusion sheet 21 to proceed vertically. The prism sheet 22 may be used to be arranged such that two or more of the prism shapes cross each other in order to increase the effect of luminance increase. In addition, it may further include a protective sheet 23 for protecting the diffusion sheet 21 and the prism sheet 22 sensitive to dust and scratches, and to prevent external impact or foreign substances from entering.

Unlike the above-described preferred embodiment, the light diffusion unit 5 may omit the light guide plate 30 according to the type of the light source unit 40. This is because the light is sufficiently diffused only by the optical sheets 20 according to the type of the light source unit 40.

The light source unit 40 includes at least one circuit board 41 disposed between the liquid crystal panel 10 and the reflecting unit 50, and a plurality of light source units disposed on the circuit board 41 to irradiate light toward the reflecting unit 50. It includes a light emitting element 42 of. In addition, the circuit board 41 further includes a substrate support 43 for supporting the bottom chassis 70.

The circuit board 41 supports and drives the light emitting element 42 on a surface opposite to the reflector 50. In addition, the auxiliary reflection unit 55 may be installed on at least one surface of both surfaces of the circuit board 41. Accordingly, the light emitted from the light emitting element 42 is reflected by the reflecting unit 50 and reaches the liquid crystal panel 10 through the light diffusing unit 5, so that the light can be sufficiently diffused into the minimum space. . Then, the light partially reflected from the light diffusing part 5 toward the circuit board 41 by the auxiliary reflecting part 55 is reflected back to the light diffusing part 5 again, or is reflected by the reflecting part 50 again. By re-reflecting the light directed to the circuit board 41, it is possible to further improve the utilization efficiency of the light. In addition, since the light emitting element 42 that generates heat at a relatively high temperature is directed toward the bottom of the reflector 50, that is, the bottom chassis 70, rather than the light diffuser 5 or the liquid crystal panel 10, the bottom chassis 70 is a bottom chassis. The heat dissipation effect by the heat dissipation member (not shown) attached to the outer rear surface of the 70 is improved, and damage to the liquid crystal panel 10 and the light diffusing portion 5 due to heat can be prevented.

The light emitting element 42 includes a light emitting diode (LED). The light emitting diode may use a light emitting diode emitting white light, or a mixture of red, green, and blue light emitting diodes may be used to mix the color emitted from each light emitting diode, thereby producing white light. In particular, when the red and green blue light emitting diodes are mixed and used as in the latter case, the light diffusion and light can be more easily secured according to the present invention.

The reflector 50 is made of a material having light diffusivity. As such a material having light diffusivity, a foamed PE-based material, that is, a material such as PET is mainly used. The reflector 50 reflects the light emitted from the light source 40 toward the light diffuser 5. In addition, by partially reflecting the light partially reflected from the light diffusing part 5 toward the reflecting part 50 back to the light diffusing part 5, the loss of light and the uniformity of the light transmitted toward the liquid crystal panel 10 are reduced. It will contribute to improving.

With this configuration, the operation and effects of the liquid crystal display device 1 according to the first exemplary embodiment of the present invention will be described. The light of the light source unit 40 may reflect the reflector 50 provided on the bottom surface of the bottom chassis 70. Since the liquid crystal panel 10 is reached through the light diffusion unit 5, the space utilization efficiency from the liquid crystal panel 10 to the bottom chassis 70 may be increased. That is, even in a relatively small space, when the light emitted from the light source unit 40 to the liquid crystal panel 10 is sufficiently diffused, or RGB LED is used as a light source, sufficient color mixing can be achieved. Therefore, the overall thickness of the liquid crystal display device 1 can be formed relatively thinly.

In the liquid crystal display device 1 according to the second exemplary embodiment of the present invention, as shown in FIG. 3, an auxiliary light diffuser is further disposed between the plurality of light emitting devices 42 and the reflector 50. This auxiliary light diffusing unit preferably includes a light guide plate 30 in particular.

That is, the optical sheet 20 is disposed between the light source 40 and the liquid crystal panel 10, and the light guide plate 30 is disposed between the light source 40 and the reflector 50.

With this configuration, the light irradiated from the light source unit 40 toward the reflector 50 is first reflected through the light guide plate 30 at the reflector 50, and then through the light guide plate 30, the optical sheets 20. Since reaching the liquid crystal panel 10 through), it is possible to further improve the uniformity of light reaching the liquid crystal panel 10. In addition, even when red, green, and blue light emitting diodes (LEDs) are used as the light emitting elements 42 of the light source unit 40, colors may be mixed in a minimum space.

As shown in FIG. 4, the liquid crystal display device 1 according to the third embodiment of the present invention includes at least one light emitting device disposed on the circuit board 41 and directly irradiating light toward the liquid crystal panel 10. (44) is further included. In addition, the light source unit 40 includes an RGB LED.

Here, among the red, green, and blue light emitting diodes used as the light emitting elements 42 and 44, light emitting diodes of relatively high luminance are provided on the surface opposite to the reflecting portion 50 of the circuit board 41. Light emitting diodes of low luminance are preferably provided on the surface of the circuit board 41 facing the liquid crystal panel 10.

With this arrangement, as in the embodiment according to the present invention, the LED of the RGB is used as the light source portion 40, and the light emitting element 42 provided on the surface opposite to the reflecting portion 50 of the circuit board 41, Red, green, and blue light emitted from the light emitting element 44 provided on the surface of the circuit board 41 opposite to the liquid crystal panel 10 may be more effectively mixed to produce white light.

As described above, according to the present invention, the light irradiated from the light source unit can be more effectively diffused to reach the liquid crystal panel. In particular, when using the LED as a light source, the distance between the light source and the liquid crystal panel for color mixing is effectively secured. Accordingly, it is possible to provide a liquid crystal display device which can exhibit excellent optical characteristics without increasing the thickness of the liquid crystal display device or adding an additional optical system.

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 cross-sectional view illustrating main parts of the liquid crystal display of FIG. 1; FIG.

3 is a cross-sectional view of main parts of a liquid crystal display according to a second exemplary embodiment of the present invention;

4 is a cross-sectional view illustrating main parts of the liquid crystal display according to the third exemplary embodiment of the present invention.

* Explanation of symbols for the main parts of the drawings

1 liquid crystal display 3 backlight assembly

5 light diffusing unit 10 liquid crystal panel

20: optical sheet 30: light guide plate

40: light source portion 41: circuit board

42: light emitting element 43: substrate support

50: reflector 55: auxiliary reflector

60: mold frame 70: bottom chassis

80: top chassis

Claims (7)

In the liquid crystal display device which has a liquid crystal panel which forms an image, A reflection part spaced apart from the rear surface of the liquid crystal panel; At least one circuit board disposed between the liquid crystal panel and the reflector; A plurality of light emitting elements provided on the circuit board to irradiate light toward the reflecting portion; And a light diffuser disposed between the circuit board and the liquid crystal panel. The method of claim 1, The light emitting device is a light emitting diode (LED), characterized in that the liquid crystal display device. The method of claim 1, And the reflector is made of a light diffusing material. The method of claim 1, And an auxiliary light diffusing unit disposed between the plurality of light emitting elements and the reflecting unit. The method of claim 4, wherein The auxiliary light diffuser includes a light guide plate. The method of claim 1, And at least one light emitting element provided on the circuit board to irradiate light toward the liquid crystal panel. The method according to any one of claims 1 to 6, And an auxiliary reflector on at least one surface of both surfaces of the circuit board.