KR20090119399A - Optical panel containing refelective minute beads for backlight - Google Patents

Abstract

PURPOSE: An optical panel containing reflective beads for backlight is provided to perform uniform brightness by distributing reflective beads on an optical panel. CONSTITUTION: An optical panel(41) is formed by a plurality of reflective beads(42), reflective polyhedron, or mixture thereof. The optical panel includes one of glass, resin, or plastic which is diffusion material. Thickness of the optical panel is 1~10mm. Reflectivity of the reflective beads or reflective polyhedron is more than 90%. A size of the reflective beads or the reflective polyhedron is 10~200um. A total volume of the reflective beads or the reflective polyhedron is 10~30% of a total volume of the optical panel.

Description

OPTICAL PANEL CONTAINING REFELECTIVE MINUTE BEADS FOR BACKLIGHT}

The present invention relates to an optical panel for backlight, and more particularly, to a light guide plate or a diffusion plate for a liquid crystal display (LCD) backlight, comprising a light diffusing panel in which a plurality of fine reflective beads or polyhedrons are distributed, together with an arrangement of a light source. The present invention relates to an optical panel for backlights in which fine reflective beads are distributed to provide uniform brightness to the backlight.

Until now, Cold Cathode Fluorescent Lamps (CCFLs) have been mainly used as backlights in backlight units (BLUs) .However, the use of mercury-containing lamps has been gradually limited. There is an urgent need for the development of lamps or light sources. Accordingly, attempts have been made to replace CCFLs with light emitting diodes (LEDs), which are suitable for low power consumption because they can operate at low voltage and have better color gamut. Nowadays, LED is mainly used as a light source for small and medium-sized LCDs with small screen sizes.

1 is a diagram showing the concept of an upward emission type BLU employing CCFL (a) and LED (b) as light sources.

As shown in (a) of FIG. 1, in the upward emission type BLU 1 employing a CCFL light source, which is a kind of line light source, the CCFL light source 3 is located on the bottom surface of the diffuser plate 4, The reflection sheet 2 directs the light emitted down from the CCFL back to the diffuser plate 4. Here, the reflective sheet is also provided on the side surface surrounding the CCFL light source 3, but is not illustrated.

Light entering through the lower surface of the diffuser plate 4 is spread by the diffusion material in the diffuser plate 4 so that the light is uniformly spread. Thereafter, the light exiting the upper surface of the diffusion plate 4 becomes more uniform through the diffusion sheet 5, and the direction of light is better due to the prism sheets 6 and 7 on the diffusion sheet 5. High brightness. Finally, the light passing through the protective film 8 is incident on the LCD panel (not shown).

As shown in (b) of FIG. 1, the BLU 11 of the upward emission type adopting LED, which is a kind of point light source, as a light source is that the light source is an LED 13 arranged on the printed circuit board 12. The configuration and functions of the remaining elements are the same as in the case of FIG. However, a portion except for the LED 13 on the printed circuit board 12 may be covered with a reflective sheet.

In the above-described BLUs (1, 11), although the LCD screen size increases in the LCD market, the thickness of the BLU is required to be reduced, and the increase in the number of light sources is suppressed proportionally.

However, as the ratio of the distance between the light sources and the BLU thickness increases, it is difficult to obtain uniform illuminance or luminance on the backlight. In particular, a problem arises in that the illuminance or luminance becomes higher than the surroundings on the optical panel immediately above the light sources 3 and 13.

A conventionally presented method for solving this problem is illustrated in FIGS. 2A-2D.

2A to 2D are diagrams illustrating embodiments in which the brightness of a backlight is uniform by configuring various optical patterns on a diffusion plate used in a conventional BLU of a top emission type.

In the example shown in FIG. 2A, the diffusion plate 22 diffuses by suppressing or suppressing excessive light coming from the light source 21 by increasing the size and density of the diffusion pattern or the reflection pattern 23 above the CCFL light source 21. The illuminance or luminance on the plate 22 is made uniform, and the example shown in FIG. 2B distributes the reflection pattern 25 on the LED light source (not shown) in the diffuser plate 24 to prevent excessive light from the LED light source. By suppressing, the illuminance or luminance on the diffusion plate 24 is made uniform.

However, in such embodiments, there is a problem in that brightness is lowered compared to input power by shielding a part of light strongly emitted from a light source using a light blocking pattern to obtain uniform illuminance or brightness. In addition, when the light blocking patterns 23 and 25 or the outline thereof are seen on the backlight, the quality of the backlight or the LCD may be degraded, and the light blocking patterns 23 and 25 are aligned with the CCFL or the LED light source. There is also a problem in that a separate assembly process is further required.

As another example, FIG. 2C illustrates that a hole is formed in the reflective metal plate 28 by varying the size and distribution density of the hole in the region corresponding to the CCFL light source 27 and the CCFL light source 27. In the region of the reflective metal plate 28 immediately above the light source 27, the density or size of the hole is reduced, and the density or size of the hole is increased in the upper portion corresponding to the light source and the light source to change the light passing rate.

The light emitted from the CCFL light source 27 travels directly to the lower surface of the reflective metal plate 28 by means of the reflective sheet 26 on the side below or directly and passes directly in the perforated region 29a, and the non-hole region ( In 29b), the incident light is reflected by the reflective metal plate 28 and returned to the reflective sheet 26 to be reflected again. When the above process is repeated, light having a relatively uniform brightness passes through the optical sheet 30 such as the diffusion sheet or the prism sheet and enters the liquid crystal panel.

The structure of FIG. 2C has a problem in that holes having different areas and different densities must be formed in the reflective metal plate 28, and the reflective metal plate 28 is aligned with the CCFL light source 27 to be assembled. The disadvantage is the need to modify the assembly process.

FIG. 2D shows a backlight in which the front wall 34 facing the liquid crystal panel in the reflective box 33 with the inner wall is uniformly dense and drilled therein, and the LED light source 32 is arranged on the opposite side. The light emitted from the LED light source 32 passes through the hole directly and the other part is reflected and then reflected back by the inner wall of the box 33 to the front face 34 again. When the above process is repeated, light having a relatively uniform brightness is incident on the liquid crystal panel.

Although the structure of FIG. 2D may solve the problem of FIG. 2C, there is a limit to secure the distance between the LED light source 32 and the front surface 34 to a certain level. In addition, there is a disadvantage that requires modification of the existing optical panel manufacturing process or backlight assembly process.

In order to solve the above problems, the present invention provides a uniform brightness when using a line light source or a point light source in the LCD backlight, when the distance between the light sources is far, or when the thickness of the backlight is thin. By distributing fine reflective beads or reflective polyhedrons in an optical panel (for example, 4, 14, 22, 24, 28, and 34 shown in FIGS. 1 and 2) to maintain consistency with existing assembly processes. It is an object of the present invention to provide an optical panel for backlights in which fine reflective beads that can obtain uniform brightness are distributed.

In order to achieve the above object, an embodiment of a backlight optical panel in which fine reflective beads are distributed according to the present invention includes a light source, a reflective sheet, an optical panel, and a backlight having a plurality of optical sheets. The panel is characterized by consisting of a plurality of fine reflective beads, reflective polyhedron or a mixture of these.

In the present invention, the optical panel is characterized by including any one of glass, resin, or plastic which is transparent to light and is a diffusion material.

In the present invention, the optical panel is characterized in that the thickness of 1 mm to 10 mm.

In the present invention, the material of the reflective bead or the reflective polyhedron is a metal having a reflective property or a resin having a reflective property or a resin coated with a reflective material.

In the present invention, the reflective bead or the reflective polyhedron is characterized in that the reflectance is 90% or more.

In the present invention, the reflective bead or the reflective polyhedron is characterized in that the size of 10 μm to 200 μm.

In the present invention, the total volume of the reflective beads or the reflective polyhedron is 10% to 30% of the total volume of the optical panel.

The backlight optical panel in which the fine reflective beads are distributed according to the present invention has an effect of providing uniform brightness on the optical panel by distributing fine reflective beads or polyhedrons in the optical panel facing the CCFL or the point light source LED. have.

In addition, since the present invention is provided in the optical panel which is a conventional backlight component, there is no need for a separate assembly process, and thus there is an advantage that the assembly cost does not increase.

1 is a view showing the concept of an upward emission BLU adopting CCFL (a) and LED (b) as a light source,

2A to 2D are views showing embodiments in which the brightness of the backlight is uniform by configuring various optical patterns on a diffusion plate used in a conventional BLU of the upward emission type.

3 is a view showing an embodiment of an optical panel for backlight having a fine reflective bead distributed in accordance with the present invention,

4 is a view showing a distribution of fine reflective polyhedrons in another embodiment of the optical panel of the present invention;

FIG. 5 is a cross-sectional view illustrating a state in which light emitted from a light source proceeds in an example of a backlight including a backlight optical panel in which fine reflective beads are distributed according to the present invention.

*** Explanation of symbols for the main parts of the drawing ***

12: printed circuit board 12a: reflecting plate

13: LED 41, 43: optical panel

42: reflective beads 44: reflective hexagonal

50, 50a to 50c: light

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the optical panel for a backlight in which the fine reflective beads are distributed according to the present invention will be described in detail.

FIG. 3 is a view showing an embodiment of an optical panel for backlight in which fine reflective beads are distributed according to the present invention.

As shown, the backlight optical panel 41 of the present invention is configured by distributing fine reflective beads 42 therein.

The material of the reflective beads 42 is preferably made of a resin coated with a reflective metal or a material having a high reflectance, or a resin having a constant reflective property. In this case, the reflectance is preferably 90% or more.

In addition, the size of the reflective beads 42 may be up to several μm to several hundred μm, more preferably 10 μm to 200 μm range.

The total volume of the reflective beads 42 in the optical panel 41 is preferably configured in a range of about 10% to 30% of the total volume of the optical panel 41.

4 is a view showing a distribution of fine reflective polyhedrons in another embodiment of the optical panel of the present invention.

As shown in the drawing, the optical panel 43 for backlight of the present invention is configured by distributing a fine reflective hexagonal body 44 therein.

Since the ratio of the material and the size of the reflective hexagonal body 44 and the total weight of the optical panel 43 is the same as described with reference to FIG. 3, a description thereof will be omitted.

As such, spherical beads and a hexahedral reflective material are distributed in the optical panels 41 and 43 shown in FIGS. 3 and 4, but various shapes of polyhedrons may be formed. That is, the reflective material may be an ellipsoid, a tetrahedron or an octahedron, and it is natural that each of them can be mixed and distributed.

FIG. 5 is a cross-sectional view illustrating a state in which light emitted from a light source proceeds in an example of a backlight including a backlight optical panel in which fine reflective beads are distributed according to the present invention.

FIG. 5 illustrates an example in which light emitted from a light source travels in a backlight having the optical panel illustrated in FIG. 3.

As illustrated, the light source exemplifies the LED 13, and the reflective sheet or the diffuse reflecting plate 12a may be disposed on the portion of the upper surface of the printed circuit board 12 where the LED 13 is not present.

The optical panel 40 of the present invention is preferably configured to include any one or more of materials such as glass, resin, plastic, etc., which is transparent to light and diffuses light, and preferably has a thickness of about 1 mm to 10 mm. Do.

For reference, a diffuser sheet, a prism sheet, a protective film, an assembled chassis, a liquid crystal panel, and the like are provided on the light source and the optical panel arranged with the reflecting plates on the lower side and the side thereof, and thus the LCD is not illustrated.

First, the movement path of the light emitted from the LED 13 as a light source will be described in detail.

A portion 50a of the light 50 emitted from the LED 13 enters the optical panel 41 and the path is deflected laterally by the reflective bead 42 to exit above the optical panel 41. As such, the light 50a is largely deflected laterally compared to the course expected in the absence of the reflective beads 42.

Some of the light 50 emitted from the LED 13 50b enters the optical panel 41 and is deflected by the reflective bead 42 to exit the optical panel 41 and face downward. 12a) is incident again into the optical panel 41 and then deflected by the reflective bead 42 to exit above the optical panel 41. At this time, the light 50b is also greatly deflected laterally compared to the course expected in the absence of the reflective beads 42.

The light 50 emitted from the light source LED 13 by the above-described method proceeds out of the optical panel 41 to the liquid crystal panel while diffusing laterally through several reflections by the reflective beads 42 and the reflecting plate 12a or the like. Done.

Therefore, the light emitted from the point light source or the line light source deflects from the original path and spreads farther, thus serving as a very good diffuser plate, and as a result, even brightness of the light source is uniformly maintained on the backlight even when the light sources are far from each other or the thickness of the backlight is thin. Will be obtained.

The optical panel in which the fine reflective beads or the reflective polyhedrons are distributed has been applied to an LCD backlight, but may be applied to a display panel, an electric signboard, an advertisement board, a signboard, and the like, which require a uniform light surface. In addition, the optical panel in which the reflective bead or the reflective polyhedron is distributed may be applied to indoor and outdoor lighting.

The present invention described above is limited to the above-described embodiments and the accompanying drawings as various substitutional modifications and changes are possible within a range without departing from the technical spirit of the present invention for those skilled in the art. It doesn't happen.

Claims (7)

A backlight comprising a light source, a reflective sheet, an optical panel, and a plurality of optical sheets, The optical panel has a plurality of fine reflective beads, a reflective polyhedron or a mixture of these distributed by the optical panel for a backlight having a fine reflective bead distributed. The method of claim 1, The optical panel for the backlight is a fine reflective bead is distributed, characterized in that the optical panel comprises any one of glass, resin, or plastic which is transparent to light and a diffusion material. The method of claim 1, The optical panel has a thickness of 1 mm to 10 mm, the optical panel for a backlight with fine reflective beads is distributed. The method of claim 1, The reflective bead or the reflective polyhedron is made of a reflective metal or a reflective optical material or a reflective reflective panel, characterized in that the reflective material is coated with a reflective material. The method of claim 4, wherein The reflective beads or the reflective polyhedron has a reflectivity of 90% or more, the optical panel for a backlight having a fine reflective beads are distributed. The method of claim 1, The reflective bead or the reflective polyhedron has a size of 10 μm to 200 μm, the optical panel for a backlight with a fine reflective bead is distributed. The method of claim 1, And a total volume of the reflective beads or the reflective polyhedron is 10% to 30% of the total volume of the optical panel.