KR20060099275A - Back light unit - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to LCDs and back light units used for advertising or lighting, and in the installation of a light guide plate, which is a component of the backlight device, is a wedge type which can exhibit relatively high efficiency optical characteristics. The present invention relates to a backlight device capable of maintaining a thin thickness of a light guide plate by overlapping two light guide plates to form a rectangular shape, and realizing high brightness optical characteristics while using a small number of light sources.

Backlight, Light Guide Plate

Description

Backlight Unit

1 is a rear view of a backlight device, FIG. 1B is a rear view of a general laptop backlight device, FIG. 1A is a rear view of a backlight device for a monitor having light sources on both sides, and FIG. Back view of backlight device for monitor and TV.

2 is a side view of the backlight device, FIG. 2A is a side view of FIG. 1B, FIG. 2B is a side view of FIG. 1A, and FIG. 2C is a side view of FIG. 1C.

3 is a rear view of the backlight device of the present invention.

4 to 7 are side views of embodiments of the backlight device of the present invention.

Explanation of symbols on the main parts of the drawings

100: light source

200: Frame

300, 300 ', 301, 302: light guide plate

400: Diffusion Plate

500: reflector

600: pattern

700, 700 ': Light source cover

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LCD and a back light unit used for advertising or lighting, and in installing a light guide plate which is a component of a backlight device, the light guide plate, which is composed of one thick plate in the prior art, is used. By forming two light guide plates so as to cross each other, the light guide plate has a relatively thinner thickness and a relatively high luminance.

In general, there are three main types of backlight devices: laptops, monitors, and TVs. First of all, a backlight device for a notebook has a light source installed at one side of a wedge plane light guide plate, and the light of the light source is properly refracted and scattered by a pattern formed by various methods on the rear side of the light guide plate to induce light evenly to the front surface.

The backlight device for a monitor is provided with light sources at both sides of the rectangular light guide plate to guide the light to the front side by a pattern formed by various methods on the rear side of the light guide plate, or a light source is installed at the rear side of the light guide plate to send the light to the front side.

Backlight device for TV has light source installed in the rear side of the front screen and there is no light guide plate so that the light of the rear light source is sent evenly through the diffusion plate.

FIG. 1B is a rear view of a general backlight device for a notebook, and FIG. 1A is a rear view of a backlight device for a monitor having light sources at both sides, and FIG. 1C is a direct-type backlight device for a monitor and a TV having a light source under the light guide plate. In the figure, 100 is a light source, 200 is a frame, 300 is a light guide plate, and 400 is a diffusion plate. Considering the characteristics of the notebook backlight device, the screen should be thin to meet the weight and weight of the notebook, the power consumption is low, and the distance between the end user (consumer) and the screen is short. As a result, a relatively low brightness rear plane light emitting device was sufficient, and a single side light source was used for the wedge-shaped light guide plate. However, since a backlight device for a monitor or TV requires a high brightness rear plane light emitting device, a notebook type backlight device configuration is not suitable. Therefore, in order to implement high brightness, the backlight device for a monitor may be provided with one or more light sources on both sides of the light guide plate, or may take part in the form of a backlight device for a TV. Similarly, in order to realize high brightness, a backlight device for a TV takes a form in which light sources are arranged in a row on the rear of a screen and installs a plurality of light sources.

2A is a side view of FIG. 1B. The shape of the light guide plate 300 is wedge-shaped to minimize the amount of light that is lost from the light incident to the light guide plate opposite to the light source. When the light is emitted from the light source 100, the path of the light is changed in the direction of the front part by refraction, scattering and reflection from the reflector 500 in the pattern 600.

FIG. 2B is a side view of FIG. 1A. The shape of the light guide plate 300 'is a plane (hexahedron) to increase the number of light sources on the side to increase the overall brightness of the backlight device. When the light is generated from the light source 100, the path of the light changes the path of the light toward the front part through scattering, refraction, and reflection in the reflector 500.

FIG. 2C is a side view of FIG. 1C. In the backlight device structure for the purpose of realizing high brightness for TV, increasing the number of light sources 100 on the side of the planar light guide plate 300 'structure of FIG. 1a has a limitation of increasing the thickness of the light guide plate, thereby acting as a light guide. Removing the light guide plate to form a plurality of light sources 100 in the rear of the front screen as shown in Figure 1c. In the light path, when light is generated from the light source 100, the light goes out toward the front part through proper scattering and refraction through the upper diffusion plate 400.

Currently, a backlight device serving as a light source of an LCD (LCD) flows in a trend that requires thinness of thickness, high brightness and low power consumption. However, commercially available backlight devices for notebooks are difficult to achieve high brightness while maintaining a thin thickness. In addition, high brightness is achieved by using a large number of light sources for commercially available large-scale backlight devices, that is, monitors and TVs. However, the design structure of the product has the disadvantage of being thick, low light source efficiency, and high power consumption.

The present invention has been devised to solve the above problems, to provide a backlight device that can maintain a light guide plate thickness thin, and can realize a high brightness optical characteristics while reducing the number of light sources.

An object of the present invention, the light guide plate formed with a pattern to control the light path of the light source, and the lamp cover which is installed on one side, both sides or the rear of the light guide plate to collect light from the light source and the light source for emitting light toward the light guide plate In the backlight device configured to include, two wedge-shaped light guide plate formed with a hemispherical lens-shaped convex pattern having a constant size on one side is formed by overlapping the surface formed with the pattern to face the rear, overlapping light guide plate on both sides It is achieved by a backlight device, characterized in that the light source is installed inside the lamp cover and the lamp cover, respectively.

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

3 is a rear view of the backlight device of the present invention, and FIGS. 4, 5, 6, and 7 are side cross-sectional views of Embodiments 1, 2, 3, and 4 of the backlight device of the present invention, respectively.

4, 5, 6 and 7, the backlight device (FIG. 3) includes a light guide plate made of a light-transmissive material and a light source for emitting light, the backlight device comprising a pattern according to the path of light of the light source. The two wedge shaped light guide plates 301 and 302 overlap each other, and the light sources 100 are provided on both sides of the overlapped light guide plates 301 and 302.

The backlight device has a patterned light guide plate (301, 302) both face the rear (Figs. 4 and 5), or the lower light guide plate 302 is facing the front and the upper light guide plate 301 toward the rear (Fig. 5 and 6) may be formed.

The lamp covers 700 and 700 ′ of the backlight device may be configured by combining only one light guide plate (FIGS. 4 and 6) or 700 by combining two light guide plates (FIGS. 5 and 7). ')

The pattern formed on the light guide plate in the backlight device may be configured as a light guide plate in which a pattern is formed, such as a prism shape having a constant angle, a prism shape having various angles, and a hemispherical lens shape having various sizes.

The backlight device may be provided with a single or a plurality of light sources on both sides.

The backlight device of the present invention may be configured in various ways depending on the direction of the light guide plate, the number of light sources, and the like.

It looks at the operating state of the backlight device according to the present invention having such a configuration.

The present invention is to provide a light guide plate having a plurality of light sources and a thickness for accommodating a plurality of light sources for the purpose of increasing the brightness of the backlight device, by reducing the number of light sources by taking a light guide plate structure of higher efficiency than the prior art, The thickness of the corresponding light guide plate can also be thinned.

According to the present invention, the light emitted from the left light source is scattered and refracted in the pattern of the lower light guide plate, and the light passes through the upper light guide plate, and the light emitted from the right light source is scattered and refracted in the pattern of the upper light guide plate. By utilizing the amount of light of the light source as efficiently as possible can use a relatively small number of light sources can realize high brightness optical characteristics.

Table 1 is a comparison of the backlight device of the present invention and the backlight device 150XH currently in mass production. 150XH is currently being mass-produced as a backlight device for monitors and has a structure as shown in FIG. 2B (Comparative Example 1). In the backlight device of the present invention manufactured for comparison, two wedge-shaped light guide plates having a hemispherical lens-shaped convex pattern having a uniform size on one side as shown in FIG. 6 are formed with one surface facing one at the rear and one facing at the front. It is a back-up device (implementation example 3) comprised so that a light source may be provided in the lamp cover and the lamp cover inside, respectively, and overlapping so that it may face.

Table 1

Comparative Example 1 Embodiment 3 thickness 6t 3t Lamp (light source) Four 2 Brightness (spec.) 3000 cd / ㎡ 3400 cd / ㎡

As can be easily seen from the data in Table 1, the present invention can configure a backlight device having a thinner, higher efficiency, and higher brightness than conventional products.

In order to verify whether the backlight device product of the present invention has the above effect, a backlight device product was manufactured and tested. Two products were manufactured, one of which consists of a wedge-shaped light guide plate formed with a hemispherical lens-shaped convex pattern having a uniform size on one side, and a surface formed with two patterns intersecting and overlapping toward the rear, and an overlapping light guide plate. A backlight device (implementation example 1) constituted by providing a lamp cover and a light source inside the lamp cover on both sides, and the other is a backlight device comprising a prism shape having a constant angle on one side in the same manner as described above (implementation example 5). 150XH and 150XO are currently being mass-produced as a backlight unit for monitors and have the structure as shown in FIG. 2B (Comparative Example 1 and Comparative Example 2). Table 2 shows data comparing the characteristics of the backlight device of the present invention and the mass-produced products.

TABLE 2

Embodiment 1 Embodiment 5 Comparative Example 1 Comparative Example 2 Light guide plate thickness 3.5t 3.5t 6t 4t Number of lamps 2 2 Four 2 Luminance (9p) 3250 cd / ㎡ 3240 cd / ㎡ 2880 cd / ㎡ 1830 cd / ㎡ Lamp current 6.0 * 2 mArms 6.0 * 2 mArms 4.5 * 4 mArms 8.0 * 2 mArms Power consumption 7.7 7.7 14 W 9.1 W Uniformity 82% 82% 75% 80%

As can be seen in Table 2, first, the backlight device of the embodiment of the present invention is compared.

Compared to the 150XH in Example 1, it has the following advantages: The light guide plate was 42% thinner than the 150XH light guide plate. The number of lamps used is half (1/2) compared to Comparative Example 1, but the brightness is 12% higher than that of Comparative Example. Power consumption is also 45% less than the comparative example.

Comparing the backlight device of the embodiment of the present invention with 150XO of Comparative Example 2 has the following advantages. The light guide plate was 13% thinner. Although the number of lamps is the same, the brightness is 90% higher than that of the device of the present invention. Power consumption is also 15% less that the backlight device of the present invention.

As can be seen from the above, it was confirmed that the backlight device of the present invention showed excellent characteristics in various items for evaluating the performance of the backlight device compared to the existing mass-production products.

As those skilled in the art to which the present invention pertains, various permutations, modifications, and changes can be made without departing from the technical spirit of the present invention. It is not.

As described above, the light source is installed on both sides of the light guide plate formed by overlapping two wedge-shaped light guide plates having a pattern formed on the rear surface thereof, which has an effect of making the thickness thinner than the backlight device of the prior art. Since the efficiency of the light source can be maximized by maintaining the light source, high brightness can be realized while using a relatively small number of light sources, thereby reducing the power consumption of the BLU and simplifying the inverter device for driving the light source. It is.

Claims (4)

A light guide plate having a pattern formed to control the light path of the light source, a light source installed at one side, both sides, or the rear of the light guide plate, and a light source cover for collecting light emitted from the light source toward the light guide plate. 2. The backlight device of claim 2, wherein two wedge-shaped light guide plates each having a pattern formed on one surface thereof are alternately overlapped, and a light source is installed on both sides of the light guide plate and a light source is installed inside the light source cover. The backlight device of claim 1, wherein the pattern is a hemispherical lens shape having a constant size, a prism shape having a constant angle, a prism shape having various angles, or a hemispheric lens shape pattern having various sizes. The backlight device according to claim 1, wherein a plurality of light sources are provided on both sides of the light guide plate. The light guide plate according to claim 1, wherein when the light guide plate is overlapped, all of the surface on which the pattern is formed faces to the rear side, all of the surface on which the pattern is formed to face the front surface, or one light guide plate has the surface on which the pattern is formed toward the front surface and the other light guide plate. Back light device, characterized in that overlapping so as to face the back.

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