KR20070025258A - Liquid crystal display - Google Patents

Abstract

An LCD(Liquid Crystal Display) is provided to obtain uniform brightness by guiding light emitted from a lamp to a dark region using a light guide function of optical fibers. An LCD includes an LCD panel, a light source(60), and an optical plate(50). The light source is located behind the LCD panel. The optical plate is placed between the LCD panel and the light source and has a plurality of light guides(51) that connect a projecting plane facing the LCD panel to a light-receiving plane facing the light source. The interval of the light guides on the projecting plane is wider than the interval of the light guides on the light-receiving plane. The light guides include optical fibers. The optical plate is made of any one of poly methyl methaacrylate and poly carbonate and includes diffusion particles.

Description

Liquid Crystal Display {LIQUID CRYSTAL DISPLAY}

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

2 is a perspective view of an optical plate according to a first embodiment of the present invention;

3 is a cross-sectional view of an optical plate according to a first embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10 liquid crystal display panel 20 mold frame

30: light adjusting member 50: optical plate

51: optical fiber bundle 51a: entrance hole

51b: exit hole 52: diffusion agent

60: lamp 70: reflective sheet

80: bottom chassis 90: top chassis

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device including an optical plate having a plurality of optical fibers.

The LCD includes a thin film transistor substrate, a color filter substrate, and a liquid crystal layer in which liquid crystal is injected between the two substrates. In addition, since the liquid crystal display is a non-light emitting device, a backlight unit for supplying light is disposed on the rear surface of the thin film transistor substrate. Light transmitted from the lamp of the backlight unit is adjusted according to the arrangement of the liquid crystals.

The backlight unit includes a light adjusting member positioned on a rear surface of the liquid crystal display panel and a light source for irradiating light to the liquid crystal display panel.

The backlight unit is classified into an edge type and a direct type according to the position of the lamp. In the direct type, a plurality of lamps are arranged in parallel on the rear surface of the liquid crystal display panel. In the edge type, a light guide plate that collects light incident from the side and sends the light upward is used, wherein the lamp is disposed on at least one side of the light guide plate.

The direct type is a method of arranging lamps, which is mainly developed as the size of a liquid crystal display device increases, and arranges one or more lamps in parallel with each other on the lower surface of the liquid crystal display panel to irradiate light on the entire liquid crystal display panel.

In the liquid crystal display device having such a direct type light source arrangement structure, a bright bright line is prominently displayed in the area of the liquid crystal display panel corresponding to the upper part of the lamp, resulting in a problem of uneven brightness.

Accordingly, an object of the present invention is to provide a liquid crystal display device with uniform luminance.

The object is a liquid crystal display panel; A light source provided at the rear of the liquid crystal display panel; It is achieved by a liquid crystal display device provided between the liquid crystal display panel and the light source, and including an optical plate having a plurality of light guides connecting the emission surface facing the liquid crystal display panel and the incident surface facing the light source.

And a distance between the light guides on the exit surface is wider than a distance between the light guides on the incident surface along the extending direction of the light source.

The optical guide is preferably made of an optical fiber.

The optical plate is made of any one of polymethyl methacrylate and polycarbonate, and preferably further includes diffusing particles therein.

The light source may be any one of a lamp and a light emitting diode.

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

The liquid crystal display device 1 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3 as follows.

As shown in FIG. 1, the liquid crystal display device 1 includes a liquid crystal display panel 10 for forming an image, a driver integrated circuit (not shown) for driving the liquid crystal display panel 10, and a liquid crystal display panel 10. A mold frame 20 supporting the edges of the < RTI ID = 0.0 >), a backlight unit for irradiating light to the back of the liquid crystal display panel 10, a bottom chassis 80 for accommodating the backlight unit and supporting the mold frame 20, A top chassis 90 is coupled to the bottom chassis 80 to cover the entire surface of the liquid crystal display panel 10.

The liquid crystal display 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. Liquid crystal (not shown). In addition, the liquid crystal display panel 10 includes polarizers 13 and 14 attached to the front surface of the color filter substrate 12 and the rear surface of the thin film transistor substrate 11 so that light passing through the liquid crystal display panel 10 is cross-polarized. It includes more. The liquid crystal display 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.

In the thin film transistor substrate 11, a plurality of gate lines and a plurality of data lines are formed in a matrix form, and thin film transistors (TFTs) are formed at intersections of the gate lines and the data lines. The signal voltage transmitted from the driver integrated circuit is applied between the pixel electrode and the common electrode of the color filter substrate 12, which will be described later, through the thin film transistor, and the liquid crystal between the pixel electrode and the common electrode is aligned according to the signal voltage to transmit light. Will be adjusted.

The color filter substrate 12 includes a color filter and a common electrode, which are formed by repeating red, green and blue or cyan, magenta, and yellow on the black matrix. The common electrode is made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). The color filter substrate 12 has a smaller area than the thin film transistor substrate 11.

The front polarizer 13 and the rear polarizer 14 are disposed to cross-polarize each other, the rear polarizer 14 polarizes the light incident on the liquid crystal display panel 10 and the front polarizer 13 serves as an analyzer. .

The driver integrated circuit has terminals for electrically connecting and is connected to ends of the gate line and the data line of the thin film transistor substrate 11 mounted on the thin film transistor substrate 11 and extending from the display area to the non-display area.

The mold frame 20 is formed along an edge of the liquid crystal display panel 10 and has a substantially rectangular shape to support the liquid crystal display panel 10 spaced apart from the backlight unit.

The backlight unit includes a light adjusting member 30 disposed in parallel to the rear surface of the liquid crystal display panel 10, a lamp 60 for irradiating light to the rear surface of the liquid crystal display panel 10 through the light adjusting member 30, and Reflective sheet 70 provided behind the optical plate 50 having the plurality of optical fibers 51 and the light source 60 to direct the light emitted from the light source 60 to the back of the liquid crystal display panel 10. It includes. In addition, the backlight unit, the mold frame 20, and the side mold are accommodated by the bottom chassis 80.

The light adjusting member 30 includes a protective sheet 31, a prism sheet 33, and a diffusion sheet 35 positioned on the rear surface of the liquid crystal display panel 10.

The diffusion sheet 35 is composed of a base plate and a bead-shaped coating layer formed on the base plate, and serves to diffuse the light from the lamp 60 to the liquid crystal display panel 10.

The prism sheet 33 and the protective sheet 31 may be provided on the diffusion sheet 35. The prism sheet 33 has a triangular prism-like prism formed on an upper surface thereof, and improves luminance by allowing light passing through the diffusion sheet 35 to proceed vertically. However, it may further include a reflective polarizing film that passes a specific kind of polarization component and reflects other polarization components in place of the prism sheet 33, and does not use the prism sheet 33 and reflects polarization. The film may be used alone.

In addition, the protective sheet 31 may further include a protective sheet 31 that protects the diffusion sheet 35 and the prism sheet 33 that are sensitive to dust and scratches, and prevents an external impact or inflow of foreign substances.

The backlight unit is classified into an edge type and a direct type according to the position of the light source. In the direct type, a plurality of lamps 60 are arranged in parallel on the rear surface of the liquid crystal display panel 10, and in the edge type, the backlight unit is incident from the side. A light guide plate is used to collect light and send the light upwardly, wherein the light source is disposed on at least one side of the light guide plate.

In the present invention, a lamp 60 is used as the light source, and a direct method in which a plurality of lamps 60 are arranged over the entire rear surface of the liquid crystal display panel 10 is applied. In this case, a cold cathode fluorescent lamp (CCFL) or an external electrode fluorescent lamp (EEFL) may be used as the light source.

Such a direct type is a lamp arrangement mainly developed as the size of the liquid crystal display device is enlarged, and one or more lamps are arranged in parallel with each other on the lower surface of the liquid crystal display panel 10 so as to be disposed on the entire liquid crystal display panel 10. It is a way of irradiating light.

About 90% of the light emitted from the lamp penetrates through the light adjusting members 30 and the polarizing plates 13 and 14 to reach the liquid crystal display panel 10. Therefore, the direct type structure in which light is directly irradiated from the rear of the liquid crystal display panel 10 has an advantage of using the strong light intensity as it is. However, at this time, the area of the liquid crystal display panel 10 corresponding to the vertical upper area of the lamp positioned at the shortest distance with respect to the lamp 60 appears bright in the shape of the lamp 60, resulting in uneven brightness.

At this time, as shown in FIG. 2, a plate-shaped optical plate 50 having an emission surface facing the liquid crystal display panel 10 and an entrance surface facing the lamp 60 is provided on the lamp 60. The optical plate 50 includes a plurality of optical fibers 51 provided to connect the optical plate 50 in the thickness direction.

The optical fiber 51 is formed in the form of a double tube including a tube-shaped core and a cladding layer surrounding the core, and has a diameter of about 100 μm to several hundred μm.

Glass and plastic may be used as the material of the optical fiber 51, but the glass material is fragile and difficult to form. Plastic optical fiber can be used to overcome this disadvantage. Plastic fiber optics consist of a core made of Polymethyl MethaAcrylate (PMMA) and a thin clad layer made of Fluorinated Poly Methyl MethaAcrylate (F-PMMA).

The upper surface of the optical fiber 51 is directed toward the liquid crystal display panel 1 and the lower surface toward the lamp 60 to guide the light from the lamp 60 to the liquid crystal display panel 1. desirable. However, since the individual optical fibers 51 are easily bent, it is difficult to maintain a constant shape, so that the bottom surfaces of the plurality of optical fibers 51 are fixed with an adhesive to form a bundle and then disposed in the optical plate 50.

The optical plate 50 is made of polymethylmethacrylate (PMMA; Polymethylmethacrylate) and polycarbonate PC which are transparent to transmit light well and have fluidity against heat; PolyCarbonate) is formed by forming a plate, and when the optical plate 50 has fluidity by heat, the bundle-shaped optical fiber 51 is disposed. At this time, the optical plate 50 may further include a bead-shaped diffuser 52 therein. The material of the diffusing agent 52 is also made of polymethylmethacrylate and polycarbonate so that the light emitted from the lamp 60 is evenly distributed while passing through the optical plate 50.

In the optical plate 50, the bundle-shaped optical fiber 51 is provided to connect in the thickness direction of the optical plate 50, and the incident hole 51a of the optical fiber 51 faces the lamp 60, and the exit hole ( 51b) faces the liquid crystal display panel 10.

The light emitted from the lamp 60 is incident through the entrance hole 51a of the lower surface of the optical fiber 51, and the refractive index of the core part inside the optical fiber 51 is higher than the refractive index of the clad. Therefore, the light proceeds to the end of the optical fiber 51 while repeating the total reflection process inside the optical fiber 51 in the form of a tube. In other words, the light emitted from the lamp 60 and entered through the entrance hole 51a at the bottom of the optical fiber 51 exits through the exit hole 51b at the top of the optical fiber 51 without loss to the outside. As described above, the optical fiber 51 has a light guide function of changing or inducing a light propagation path in a desired direction.

By using the light guide function of the optical fiber 51, the light emitted from the lamp 60 may be led to a region where the dark portion appears because the lamp 60 is not provided, thereby making it possible to make the luminance of the light uniform.

3A and 3B are perspective views showing the entrance face and the exit face of the optical plate 50, respectively.

At this time, the incident holes 51a of the optical fiber 51 provided on the incident surface of the optical plate 50 are densely arranged in the upper part of the lamp 60 at a tight interval. As shown in FIG. 3B, the emission holes 51b provided on the emission surface of the optical plate 50 are spaced apart from each other at a wide interval to face the liquid crystal display panel 10. Accordingly, the light emitted from the lamp 60 and entering the incident hole 51a passes through the optical fiber 51 and then exits through the exit holes 51b which are widely spaced from each other, thereby being evenly distributed toward the liquid crystal display panel 10. do. Therefore, the brightness of light is improved.

According to another embodiment of the present invention, the liquid crystal display device 1 has an exit surface facing the liquid crystal display panel 10 and a plate-shaped optical plate 50 having an entrance surface facing the lamp 60. The optical plate 50 includes a plurality of optical fibers that extend in the thickness direction of the optical plate 50.

The incident hole of the optical fiber 51 fixed in the bundle and provided in the optical plate 50 is dense along the area corresponding to the upper portion of the lamp 60 on the incident surface of the optical plate 50 as in the first embodiment. To be prepared. However, the exit hole is located in an area where the lamp 60 is not provided on the exit surface of the optical plate 50.

Light emitted from the lamp 60 and entered through the entrance hole 51a of the optical fiber 51 is guided to exit through the exit hole 51b of the optical fiber bundle 51 without loss to the outside. Therefore, since the lamp 60 is not provided and light can be directed toward the exit hole 51b of the optical fiber bundle 51, the luminance of the liquid crystal display panel 10 becomes uniform.

The side molds disposed on both sides of the bottom chassis 80 are provided in a step shape in which the inside is not filled. Side mold is provided with a plurality of coupling grooves on the surface facing the lamp 60, both ends of the lamp 60 extending in the longitudinal direction is coupled to the coupling groove is protected from the flow of the product and external impact.

The reflective sheet 70 is positioned between the lamp 60 and the bottom chassis 80 to reflect light from the lamp 60 and to supply the light toward the diffusion film 35. The reflective sheet 70 may be made of polyethylene terephthalate (PET) or polycarbonate (PC). The reflective sheet 70 is attached to the bottom surface of the bottom chassis 80 and is provided with grooves having the same size and shape as the support body 63 of the lamp support member 60.

The backlight unit, the mold frame 20, and the side mold are accommodated by the bottom chassis 80, and the bottom chassis 80 is coupled to the top chassis 90. The top chassis 90 has a display window so that the effective surface of the liquid crystal display panel 10 is exposed to the outside, and accommodates the mold frame 20 and is coupled to the bottom chassis 80.

As described above, according to the present invention, a liquid crystal display device with improved luminance is provided.

Claims (7)

A liquid crystal display panel; A light source provided behind the liquid crystal display panel; And an optical plate provided between the liquid crystal display panel and the light source, the optical plate having a plurality of light guides connecting the emission surface facing the liquid crystal display panel and the incident surface facing the light source. The method of claim 1, And a distance between the light guides on the exit surface is wider than a distance between the light guides on the incident surface along the extending direction of the light source. The method of claim 1, The optical guide is a liquid crystal display, characterized in that the optical fiber. The method of claim 1, And the optical plate is made of any one of polymethyl methacrylate and polycarbonate. The method of claim 1, The optical plate further comprises a diffusion particle. The method of claim 5, The diffusion particles are made of any one of glass, polycarbonate and polymethyl methacrylate. The method of claim 1, The light source comprises a lamp and a light emitting diode.

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