KR20000055299A - A Backlight System for Liquid Crystal Display Devices - Google Patents

Abstract

PURPOSE: A backlight system for a liquid crystal display device is provided to reduce the number of components of the backlight system in order to increase the yield of the manufacturing process. CONSTITUTION: A backlight system for a liquid crystal display device includes a light source(20), an optical waveguide plate(30), a reflection plate(28), a dispersing/focusing plate(40), and a focusing plate(50). The light source(20) includes an optical source and a reflection roof. The optical waveguide plate(30) converts the light from the light source into a light from a plane source. The reflection plate(28) is implemented under the optical waveguide plate(30). The dispersing/focusing plate(40) is implemented on the optical waveguide plate(30). The focusing plate(50) is implemented on the dispersing/focusing plate. The lower surface of the optical waveguide plate is made to be flat while the upper surface of the optical waveguide plate is made by arranging fine lenses in a predetermined pattern.

Description

Backlight System for Liquid Crystal Display Devices

The present invention relates to a backlight system for a liquid crystal display device, and more particularly, to a backlight system for a liquid crystal display device that can improve productivity and reduce costs by reducing the number of optical components.

In general, a liquid crystal display device used for a liquid crystal display device, in particular, a monitor of a portable computer such as a notebook computer, uses a backlight system so as to maintain good visibility at all times without being influenced by the brightness of ambient light.

As shown in FIG. 8, a conventional backlight system for a liquid crystal display includes a lamp unit including a fluorescent lamp 2 and a reflector 4 as a light source, a reflector 6, a light guide 8, and a first diffuser 10. And a first light collecting plate 12, a second light collecting plate 14, and a second diffusion plate 16.

In the above, optical components such as the reflector 6, the light guide 8, the first diffuser 10, the first condenser 12, the second condenser 14, and the second diffuser 16 may emit light to a user. It is used to concentrate and to prevent unnecessary waste of energy and to enable longer operation times.

The light guide plate 8 is mainly formed of an optically transparent material such as PMMA resin, and a white reflective material such as TiO ₂ is printed in a predetermined pattern on the lower surface thereof, and the upper surface thereof is formed flat.

The first diffusion plate 10 is used to cover the pattern printed on the lower surface of the light guide plate 8.

The first light collecting plate 12 is positioned above the first diffuser plate 10, and the light incident surface from the first diffuser plate 10, which is a lower surface of the first light collecting plate 12, is flat. The light exiting surface is formed by arranging a lenticular lens made of a right isosceles triangle having a fine cross section in a predetermined pattern.

The second light collecting plate 14 is positioned to face the first light collecting plate 12 and has the same structure as the first light collecting plate 12.

That is, the second light collecting plate 14 has a plane in which light is incident from the first light collecting plate 12, which is a lower surface, and is flat, and the light exiting from the upper surface of the second light diffusing plate 16 has a fine cross section at a right angle. A lenticular lens made of an isosceles triangle is arranged in a predetermined pattern.

The conventional backlight system for a liquid crystal display device mainly uses a method of arranging the first light collecting plate 12 and the second light collecting plate 14 perpendicular to each other, which is the method described in US Pat. No. 4,542,449.

In addition, the conventional backlight system for a liquid crystal display device uses the second diffusion plate 16 on the second light collecting plate 14 to suppress the occurrence of interference fringes.

The conventional backlight system for a liquid crystal display device uses too many optical components to concentrate light on a user to prevent unnecessary waste of energy and to enable a longer operation time, thereby not only causing a price increase but also a relative factor. As a result, the assembling process is complicated, causing a problem of reduced productivity.

SUMMARY OF THE INVENTION An object of the present invention is to provide a backlight system for a liquid crystal display device that is easy to assemble and has a simple structure by reducing the number of optical components from six to four while maintaining optical characteristics.

1 is an exploded perspective view schematically showing an embodiment of a backlight system for a liquid crystal display according to the present invention.

Figure 2 is a partially enlarged plan view showing an embodiment of a light guide plate according to the present invention.

Figure 3 is a partially enlarged cross-sectional view showing an embodiment of a light guide plate according to the present invention.

Figure 4 is a partially enlarged cross-sectional view showing an embodiment of a diffusion light collecting plate according to the present invention.

Figure 5 is a partially enlarged cross-sectional view showing an embodiment of a light collecting plate according to the present invention.

6 is a graph showing luminance characteristics according to vertical viewing angles of a backlight system for a liquid crystal display and a backlight system for a conventional liquid crystal display according to the present invention.

7 is a graph showing luminance characteristics according to left and right viewing angles of the backlight system for a liquid crystal display device and the conventional backlight system for a liquid crystal display device according to the present invention.

8 is an exploded perspective view showing a conventional backlight system for a liquid crystal display.

In order to achieve the above object, a liquid crystal display backlight system proposed in the present invention includes a light source unit for emitting light, a light guide plate for converting light emitted from the light source unit into a surface light source, and a liquid crystal panel through the light guide plate. A reflecting plate for reflecting the light traveling toward the opposite side toward the liquid crystal panel, a light diffusing plate for diffusing and condensing the light traveling toward the liquid crystal panel by the light guide plate and the reflecting plate, and a light diffused and collected while passing through the light diffusing plate It includes a light collecting plate for condensing.

The upper surface of the light guide plate is formed by arranging a plurality of fine semi-convex lenses in a predetermined pattern, and on the lower surface of the diffusion light collecting plate, irregularities are formed in an arbitrary pattern for light diffusion, and the upper surface is an isosceles for light condensing. A plurality of fine lenticular lenses having a triangular cross section is formed, and a plurality of fine lenticular lenses having an isosceles triangular cross section is formed on the upper surface of the light collecting plate.

Next, a preferred embodiment of a backlight system for a liquid crystal display according to the present invention will be described in detail with reference to the drawings.

First, as shown in FIG. 1, an embodiment of a backlight system for a liquid crystal display according to the present invention includes a light source unit 20 for emitting light and a light guide plate for converting light emitted from the light source unit 20 into a surface light source. 30 and a reflector 28 for reflecting light traveling toward the liquid crystal panel 60 through the light guide plate 30 toward the liquid crystal panel 60, and the light guide plate 30 and the reflector 28. The light collecting plate 40 includes a light collecting plate 40 for diffusing and condensing light traveling toward the liquid crystal panel 60, and a light collecting plate 50 for condensing the light diffused and collected while passing through the light collecting plate 40.

The light source unit 20 is installed on one side of the light guide plate 30, and when power is applied, the light source 22 emits light, and the light guide plate 30 emits light emitted from the light source 22. It consists of a reflector 24 reflecting toward.

As the light source 22, a hot cathode fluorescent lamp, a cold cathode fluorescent lamp, or the like is used.

The light guide plate 30 is made of an optically transparent resin (for example, PMMA resin).

The lower surface 34 of the light guide plate 30 is formed flat, as shown in FIG. 3, and the reflective plate 28 is provided in contact with each other.

As shown in FIGS. 2 and 3, the diffuser plate 40 is provided in contact with the upper surface 32 of the light guide plate 30, and is formed by arranging very fine semi-convex lenses 36 in a predetermined pattern. do.

The semi-convex lens 36 is formed to have a diameter d of 100 μm or less, and particularly preferably formed to have a diameter d of 50 μm or less.

The semi-convex lens 36 is formed such that the relationship between the diameter d and the height h satisfies the following equation (1).

0 <h ≤ d / 2

In the above, d represents the diameter of the half convex lens, and h represents the height of the half convex lens.

In particular, the semi-convex lens 36 is preferably formed such that the relationship between the diameter d and the height h satisfies the following expression (2).

0 <h ≤ d / 4

In FIG. 2, the anti-convex lenses 36 are arranged at regular intervals. However, in the light guide plate 30, the liquid crystal panel 60 is mounted on the backlight system for the liquid crystal display device according to the present invention. When a liquid crystal display device is manufactured, the pattern of arranging the semi-convex lenses 36 at regular intervals may be modified in order to secure the overall luminance uniformity on the screen. The description of the part does not limit the essential problem of the present invention.

The upper surface 32 of the light guide plate 30 may be formed in an irregular pattern while maintaining the same number of semiconvex lenses 36 per unit area.

The diffusion light collecting plate 40 is positioned in contact with the upper surface of the light guide plate 30 and consists of three layers.

As shown in FIG. 4, the diffusion light collecting plate 40 includes a base layer 42 located in the middle, and a diffusion layer positioned below the base layer 42 and receiving light from an upper surface of the light guide plate 30. And a light collecting layer 46 positioned on the base layer 42 and in contact with the bottom surface of the light collecting plate 50.

The base layer 42 of the diffusion light collecting plate 40 is a layer existing for manufacturing convenience and requires an optically transparent property.

The diffusion layer 44 of the diffusion light collecting plate 40 is a layer for diffusing light incident from the light guide plate 30, and irregularities are formed in an arbitrary pattern.

The diffusion layer 44 in which the irregularities are formed in an arbitrary pattern as described above may be formed by mixing a fine glass bead of a predetermined size with a thermosetting resin or an ultraviolet curable resin and coating it on the base layer 42. .

In addition, the diffusion layer 44 may be formed by coating a thermosetting resin or an ultraviolet curable resin on the base layer 42 using an embossing roll that is embossed or engraved in an arbitrary pattern. Various methods can be used as long as the irregularities can be formed in any pattern.

An important function of the diffusion layer 44 is a diffusion function of light incident from the light guide plate 30, which may be represented by a physical quantity called haze.

In the present invention, the diffusion layer 44 is formed to have a haze value of about 10 to 70%, and a haze value of about 20 to 40% is particularly preferable.

The light collecting layer 46 of the diffusion light collecting plate 40 is a layer for collecting light passing through the diffusion layer 44 and the base layer 42, and has a plurality of fine lenticulars having an isosceles triangular cross section as shown in FIG. 4. The lenses 47 are formed in a predetermined pattern.

The lenticular lens 47 is formed so that the center angle α of the isosceles triangle is in the range of 70 to 110 degrees in cross section.

The lenticular lens 47 formed on the light collecting layer 46 of the light diffusing plate 40 is arranged in parallel with the array direction of the fluorescent lamp whose processing direction is the light source 22 described above.

The light collecting plate 50 is positioned in contact with the upper surface of the light collecting layer 46 of the diffusion light collecting plate 40 and consists of two layers.

As shown in FIG. 5, the light collecting plate 50 is positioned below and is in contact with the light collecting layer 46 of the diffusion light collecting plate 40, and is positioned above the base layer 52. The light collecting layer 54 collects light passing through the diffusion light collecting plate 40.

The base layer 52 of the light collecting plate 50 may be formed in the same configuration as the base layer 42 of the diffusion light collecting plate 40, and may be optically formed as a layer existing for convenience of manufacturing the light collecting plate 50. Transparent properties are required.

The light collecting layer 54 of the light collecting plate 50 can be formed in the same configuration as the light collecting layer 46 of the diffusion light collecting plate 40.

Like the light collecting layer 46 of the light diffusing plate 40, the light collecting layer 54 of the light collecting plate 50 also has a plurality of fine lenticular lenses 55 having an isosceles triangular cross section as shown in FIG. 5. Formed by arranging in

The lenticular lens 55 is formed so that the center angle β of the isosceles triangle is in the range of 70 to 110 degrees in cross section.

The lenticular lens 55 formed on the light collecting layer 54 of the light collecting plate 50 is arranged in parallel with the array direction of the fluorescent lamp whose processing direction is the light source 22 described above.

That is, the processing direction of the lenticular lens 55 formed in the light collecting layer 54 of the light collecting plate 50 and the processing direction of the lenticular lens 47 formed in the light collecting layer 46 of the diffusing light collecting plate 40 and The arrangement directions of the fluorescent lamps as the light sources 22 are all parallel.

In addition, when the haze value of the diffusion layer 44 of the diffusion light collecting plate 40 is small, an interference fringe may appear. To avoid this, a lenticular lens formed in the light collecting layer 46 of the diffusion light collecting plate 40 is used. The processing direction of 47 and the processing direction of the lenticular lens 55 formed on the light collecting layer 54 of the light collecting plate 50 are arranged to be slightly shifted. Also in this case, the processing directions of the two lenticular lenses 47 and 55 and the arrangement direction of the fluorescent lamp which is the light source 22 are basically parallel.

Basically parallel in the above means that the arrangement direction of two components parallel to each other is within a range of 10 °.

Each of the layers constituting the diffusion light collecting plate 40 and the light collecting plate 50 should have a very low light absorption or no light absorption in the visible light region.

6 and 7 illustrate luminance characteristics according to vertical, horizontal, and left and right viewing angles of the liquid crystal display backlight system and the conventional liquid crystal display backlight system according to the present invention.

6 and 7, filled points indicate luminance according to vertical and horizontal viewing angles of the liquid crystal display backlight system according to the present invention, and empty points indicate upper and lower portions of the liquid crystal display backlight system. And luminance according to left and right viewing angles.

6 and 7, the horizontal axis represents the viewing angle [theta], and the vertical axis represents the luminance L. In FIG.

In FIG. 6, when the viewing angle θ is 0, the front face is shown. When the viewing angle θ is positive, the upper side is seen from the user side, and when the viewing angle θ is negative, Shown downward from the user side.

In FIG. 7, when the viewing angle θ is 0, the front face is shown, when the viewing angle θ is positive, the right side is seen from the user side, and when the viewing angle θ is negative, Shown on the left side from the user side.

The light source 22 and the fluorescent lamp 2 of the backlight system for the liquid crystal display device and the backlight system for the conventional liquid crystal display device according to the present invention are located below the user side and arranged to be long in the horizontal direction.

As can be seen from FIG. 7, in the luminance characteristics of the left and right viewing angles, the liquid crystal display backlight system according to the present invention exhibits higher luminance values at all viewing angles θ than the conventional backlight system for liquid crystal display devices.

As can be seen from FIG. 6, the luminance characteristics of the vertical viewing angle also show luminance values that are inferior to those of the backlight system for liquid crystal display according to the present invention, compared to the backlight system for the conventional liquid crystal display.

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. Belongs to the scope of.

According to the backlight system for a liquid crystal display device according to the present invention as described above, the number of optical components to be assembled is conventionally six (for example, a reflecting plate, a light guide plate, a first diffusion plate, a first light collecting plate, a second light collecting plate, and a second diffusion plate). Plate) is reduced to four (for example, reflecting plate, light guide plate, diffused light collecting plate, light collecting plate), so the structure is simple and easy to assemble.

This improves productivity and reduces costs.

Claims (17)

A backlight system used as a light source of a liquid crystal display device, A light source unit comprising a light source and a reflection shade; A light guide plate for converting light emitted from the light source unit into a surface light source; A reflection plate positioned below the light guide plate; A diffusion light collecting plate positioned on the light guide plate; And A light collecting plate positioned on the diffusion light collecting plate; The light source unit is located on one side of the light guide plate, The lower surface of the light guide plate is flat and the upper surface is formed by arranging fine semi-convex lenses in a predetermined pattern. On the lower surface of the diffusion light collecting plate is formed a diffusion layer for diffusing light from the light guide plate, On the upper surface of the diffusion light collecting plate is formed by arranging a plurality of fine lenticular lenses having an isosceles triangle cross section, The lower surface of the light collecting plate is flat and the upper surface is formed by arranging a plurality of fine lenticular lenses having an isosceles triangle cross section, The processing direction of the lenticular lens formed on the upper surface of the diffusing light collecting plate is formed in the range of -10 to +10 degrees with the arrangement direction of the light source unit. A backlight system for a liquid crystal display device, wherein an angle between the processing direction of the lenticular lens formed on the upper surface of the light collecting plate and the alignment direction of the light source unit is in the range of -10 to + 10 °. The method of claim 1, The light guide plate is a backlight system for a liquid crystal display device made of an optically transparent resin. The method of claim 2, The semi-convex lens formed on the upper surface of the light guide plate has a height greater than zero and less than or equal to a radius, the backlight system for a liquid crystal display device. The method of claim 2, The semi-convex lens formed on the upper surface of the light guide plate has a height greater than zero and smaller than or equal to a value divided by a radius of two. The method according to any one of claims 1, 3 and 4, A backlight system for a liquid crystal display device, wherein the diameter of the semi-convex lens formed on the upper surface of the light guide plate is 100 μm or less. The method according to any one of claims 1, 3 and 4, A backlight system for a liquid crystal display device, wherein the diameter of the semi-convex lens formed on the upper surface of the light guide plate is 50 μm or less. The method of claim 1, A backlight system for a liquid crystal display device, wherein the haze value of the lower surface of the diffuser plate is in a range of 10 to 70%. The method of claim 1, A backlight system for a liquid crystal display device, wherein the haze value of the lower surface of the diffuser plate is in a range of 20 to 40%. The method according to claim 7 or 8, The diffusion layer formed on the lower surface of the diffusion light collecting plate is formed by forming irregularities in an arbitrary pattern. The method according to claim 7 or 8, The diffusion layer formed on the lower surface of the diffusion light collecting plate is formed by coating glass beads on a transparent substrate by mixing glass beads with a thermosetting resin or an ultraviolet curing resin. The method according to claim 7 or 8, And a diffusion layer formed on the bottom surface of the diffusion light collecting plate by coating a thermosetting resin or an ultraviolet curable resin on a transparent base layer using an embossed or embossed roll. The method of claim 1, The lenticular lens formed on the upper surface of the diffusion light collecting plate has a center angle of an isosceles triangle cross section in the range of 70 to 110 degrees. The method of claim 1, And a processing direction of the lenticular lens formed on the upper surface of the diffusion light collecting plate so that the processing direction of the lenticular lens is parallel to the alignment direction of the light source unit. The method of claim 1, The lenticular lens formed on the upper surface of the light collecting plate has a center angle of an isosceles triangle section in the range of 70 to 110 degrees. The method of claim 1, And a processing direction of the lenticular lens formed on the upper surface of the light collecting plate is arranged so as to be parallel to the arrangement direction of the light source unit. As a backlight system, A light source unit comprising a light source and a reflection shade; A light guide plate for converting light emitted from the light source unit into a surface light source; A reflection plate positioned below the light guide plate; A diffusion light collecting plate positioned on the light guide plate; And A light collecting plate positioned on the diffusion light collecting plate; The light source unit is located on one side of the light guide plate, The lower surface of the light guide plate is flat and the upper surface is formed by arranging fine semi-convex lenses in a predetermined pattern. On the lower surface of the diffusion light collecting plate is formed a diffusion layer for diffusing light from the light guide plate, On the upper surface of the diffusion light collecting plate is formed by arranging a plurality of fine lenticular lenses having an isosceles triangle cross section, The lower surface of the light collecting plate is flat and the upper surface is formed by arranging a plurality of fine lenticular lenses having an isosceles triangle cross section, The processing direction of the lenticular lens formed on the upper surface of the diffusing light collecting plate is formed in the range of -10 to +10 degrees with the arrangement direction of the light source unit. A liquid crystal display device using a backlight system having an angle in which a processing direction of a lenticular lens formed on an upper surface of the light collecting plate is formed with an arrangement direction of the light source unit is in a range of -10 to + 10 °. In the backlight system used as the light source of the liquid crystal display device, A light source unit comprising a light source and a reflection shade; A light guide plate for converting light emitted from the light source unit into a surface light source; A reflection plate positioned below the light guide plate; A diffusion light collecting plate positioned on the light guide plate; And A light collecting plate positioned on the diffusion light collecting plate; The light source unit is located on one side of the light guide plate, The lower surface of the light guide plate is flat and the upper surface is formed by arranging fine semi-convex lenses in a predetermined pattern. On the lower surface of the diffusion light collecting plate is formed a diffusion layer for diffusing light from the light guide plate, On the upper surface of the diffusion light collecting plate is formed by arranging a plurality of fine lenticular lenses having an isosceles triangle cross section, The lower surface of the light collecting plate is flat and the upper surface is formed by arranging a plurality of fine lenticular lenses having an isosceles triangle cross section, The processing direction of the lenticular lens formed on the upper surface of the diffusing light collecting plate is formed in the range of -10 to +10 degrees with the arrangement direction of the light source unit. A method of arranging a backlight system for a liquid crystal display device such that an angle formed by the processing direction of the lenticular lens formed on the upper surface of the light collecting plate is in the range of -10 to +10 degrees.