KR101066755B1 - Edge lighting back light unit - Google Patents

Abstract

The present invention relates to a side dimming type backlight device capable of improving the appearance of light emitted from the upper side by forming a prism shape and a dot shape light pattern on the upper and lower surfaces of the light guide plate, wherein a plurality of light emitting diode light sources are arranged on one side of the light guide plate. And a prism sheet for stacking and dispersing light, which is stacked on an upper side of the light guide plate, wherein the upper surface of the light guide plate is configured to disperse and collect light incident from the light source and to emit the light upward. The height is lowered from the miner to the light guide side, and a prism pattern having a rounded vertex of the mountain is formed in the light guide direction, and a dot for scattering and dispersing light incident into the light guide plate on the bottom surface of the light guide plate and outputting the light to the top of the light guide plate Pattern becomes denser as it goes toward light portion Air, characterized in that is configured to improve the properties of light emitted by the light guide plate upper side.

Backlight, Light Guide Plate, LED Array, Light Pattern, Moire

Description

Side illuminated backlight unit {EDGE LIGHTING BACK LIGHT UNIT}

The present invention relates to a side dimming backlight device, and more particularly, to a side dimming backlight device capable of improving the appearance of light emitted upward by forming a prism shape and a dot shape light pattern on upper and lower surfaces of a light guide plate, respectively. .

In general, a liquid crystal display (LCD) is widely used as a flat panel display because it can be driven using low power and has a vivid color reproduction ability. However, unlike CRTs and PDPs, LCDs are non-light-emitting devices that do not emit light directly, and require a separate backlight unit using fluorescent lamps to irradiate light from the back of the LCD panel to the panel. do.

Back light used in the liquid crystal display is classified into a front dimming type (or direct type) and a side dimming type (or edge type) according to a method of disposing a light source. Direct-lighting is a method of arranging a light source on a flat plate. Since the shape of the light source appears on the liquid crystal panel, it is necessary to secure and maintain a sufficient space between the light source and the liquid crystal. Since it must be installed separately, there is a limit in thinning. Edge-lighting is a method of distributing light to the entire surface by using a light guide panel after installing a light source on the outside of a flat plate, which has a problem of low luminance and highly optical processing technology for the light guide plate. Is required.

At this time, the light source of the back light device may be a fluorescent lamp such as CCFL (Cot Cathode Fluorescent Lamp), HCFL (Hot Cathode Fluorescent Lamp), EEFL (External Electrode Fluorescent Lamp), LED (Light Emitting Diode) device, EL (Electro) Luminescence element is mainly used.

As shown in FIG. 1, a conventional side dimming backlight device has a bottom surface of a light guide plate 30 that scatters light of a point light source emitted from a light emitting diode (hereinafter, referred to as “LED”) light source 10 and converts it into a surface light source. Reflective plate 20 for reflecting light to the upper side is provided on the upper side of the light guide plate 30, various optical sheets such as prism sheet 40 and diffusion sheet 50 to improve the brightness by refracting and condensing light Is located. In general, a plurality of LED 10 modules are arranged on one side of the light guide plate 30, and the light guide plate 30 is formed in a wedge shape in which the light incident part to which light is incident is thick and thinner toward the opposite light guide part. .

In the side dimming type backlight device having such a structure, light emitted from the LED 10 is incident to the light incident portion of the light guide plate 30, and the light guide plate 30 scatters and uniformizes the light of the LED incident to the point light source, thereby converting the surface light source. In addition, the reflective plate 20 reflects the light directed downward from the light guide plate 30 to the upper side of the light guide plate 30 to increase the light efficiency. The light diffused by the optical sheets 40 and 50 positioned above the light guide plate 30 is refracted and collected to improve luminance.

However, such a conventional backlight device does not efficiently disperse light incident on the light guide plate, and thus, a plurality of prism sheets and diffusion sheets should be provided on the upper side. In addition, a hot spot may be generated by the strong LED light on the light incident part of the light guide plate, and a moire pattern may be generated by the interference of light. In order to personalize such optical characteristics, a plurality of diffusion sheets must be provided on the upper side of the light guide plate.

 As a result, the overall thickness of the side-illumination backlight device is thick, and thus there is a limitation in slimming, and there is a problem in that assembly of the product is complicated.

The side dimming backlight device according to the prior art has a problem in that a plurality of prism sheets and diffusion sheets must be provided on the light guide plate in order to realize excellent light characteristics.

The present invention has been proposed in order to solve the above problems, in the side-illumination type backlight device, a light diffusion sheet is formed on the upper and lower surfaces of the light guide plate to efficiently collect, disperse and diffuse light, laminated on the upper side The purpose of the present invention is to provide a backlight device capable of slimming the thickness by eliminating the same, and at the same time removing the hot spots or the moire phenomenon to exhibit excellent optical characteristics.

In the present invention for achieving the above object is a side light type backlight device comprising a plurality of light emitting diode light source is arranged on one side of the light guide plate, stacked on the light guide plate and comprising a prism sheet for condensing and dispersing light, On the upper surface of the light guide plate, in order to disperse and collect light incident from the light source and to emit the light toward the upper side, the height is lowered from the light incident portion toward the light facing portion, and a prism pattern having a rounded vertex of the mountain is formed in the direction of the light facing portion. On the lower surface of the light guide plate, a dot pattern for scattering and dispersing light incident into the light guide plate and outputting the light to the upper surface of the light guide plate is formed closer to the light guide part, thereby improving characteristics of light emitted to the upper side of the light guide plate. do.

In the above configuration, the prism pattern has an angle α1 of 80 ° ≦ α1 ≦ 110 °, a radius of curvature R1 of 0 <R1 ≦ 0.9 * P1 with respect to the prism pattern spacing P1, and The maximum height D on the miner side is formed to be continuously reduced to the light projecting side with D ≦ 0.5 * P1 with respect to the prism pattern spacing P1, and the dot pattern has a curvature radius R2 of 0 <R2 ≦ 30 μm. It is characterized by.

In the above-described configuration, the prism sheet has an angle α2 of the top surface of 85 ° ≦ α2 ≦ 95 °, and the bottom surface of the prism sheet is mated to prevent wet out phenomenon.

In the above-described configuration, the prism sheet 400 is characterized in that the diffusion type additive is added so that the haze has a value of 10% to 40%.

The side dimming type backlight device according to the present invention can eliminate the diffusion sheet stacked on the upper side of the light guide plate, thereby simplifying the structure and improving the assembly efficiency and slimming of the backlight device.

In addition, light patterns are formed on the upper and lower surfaces of the light guide plate to efficiently collect, disperse, and diffuse light, thereby exhibiting excellent optical properties by removing a phenomenon such as moire even without a separate diffusion sheet.

The technical problems achieved by the present invention and the practice of the present invention will be more clearly understood by the preferred embodiments of the present invention described below. The following examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is an exploded perspective view of a side dimming backlight device according to an embodiment of the present invention.

Referring to FIG. 2, the side dimming backlight device according to the embodiment of the present invention, as shown, the light guide plate 300 for scattering the light of the point light source emitted from the LED 100 to convert to a surface light source, and the light guide plate ( The lower side of the 300 is provided with a reflecting plate 200 for reflecting light upward, the upper side of the light guide plate 300 is provided with a prism sheet 400 for condensing and dispersing the light emitted from the light guide plate 300. . In addition, although not shown, the above components are fastened by a cover bottom and a guide bottom constituting the outer housing. In the side-illumination type backlight device having the above configuration, the configuration of the LED 100 and the reflector 200 is a configuration to which general known techniques are applied, and detailed description thereof will be omitted.

The light guide plate 300 according to the embodiment of the present invention is configured to convert the light of the point light source emitted from the LED 100 into a surface light source and emit it to the upper side. It is formed in the shape of a wedge that becomes thinner. Here, the light incident part refers to the side on which light is incident, and the light incident part refers to the opposite side.

A prism-shaped light pattern (hereinafter, referred to as a 'prism pattern') is formed on the upper surface of the light guide plate 300 so as to condense and disperse light emitted upwards to remove a hot spot or moire phenomenon. In addition, a dot-shaped light pattern (hereinafter, referred to as a 'dot pattern') is formed on the lower surface to control the angle of light emitted to the upper side of the light guide plate by scattering and dispersing light incident to the light guide plate 300.

In general, a side dimming backlight device using an LED as a light source includes a plurality of LEDs arranged near the light incident part of the light guide plate, and when a strong LED light is incident on the light incident part side of the light guide plate and is emitted to the upper surface, As a result, moire phenomena are generated on the upper surface of the light guide plate near the light incident part. Since the moire pattern degrades the light characteristics in the backlight device, a plurality of diffusion sheets (50 in FIG. 1) should be provided on the light guide plate.

The prism pattern 310 and the dot pattern 320 are configured to remove such moire patterns, and are formed on the top and bottom surfaces of the light guide plate 300, respectively. According to the patterns 310 and 320, the side dimming backlight device according to the embodiment of the present invention does not include an optical sheet such as a diffusion sheet, thereby improving assembly performance and exhibiting excellent optical characteristics while achieving slimming. Hereinafter, a detailed structure of the light guide plate according to the embodiment of the present invention will be described.

3 is a perspective view showing a light guide plate according to an embodiment of the present invention, Figure 4 is a plan view showing a light guide plate according to an embodiment of the present invention, Figure 5 is a bottom view showing a light guide plate according to an embodiment of the present invention, Figure 6 is a side cross-sectional view showing a detailed structure of a light guide plate according to an embodiment of the present invention, Figure 7 is a front sectional view showing a detailed structure of a light guide plate according to an embodiment of the present invention.

The prism pattern 310 is formed on the upper surface of the light incident part side of the light guide plate 300 as shown, and is formed to be inclined so that the height of the mountain is lowered toward the light guide part inside the light guide plate. Specifically, the prism pattern 310 is preferably formed so that the height is 0 at the position of the length (L) of up to 30mm with respect to the light incident surface edge of the light guide plate 300 so that the pattern disappears.

In addition, the prism pattern 310 is formed in a round shape of the peak of the peak, wherein the angle of the angle (α1) is formed between 80 ° to 110 °, the radius of curvature R1 of the rounded mountain is the prism pattern 310 ) Is formed to be 0.9 * P1 or less with respect to the spacing P1 where it is formed, and the maximum height D of the light incident portion is constant to an initial height of 0.5 * P1 or less with respect to the spacing P1 where the prism pattern 310 is formed. It is preferably formed to be continuously reduced to the length (L). At this time, the interval P1 of the prism pattern 310 is formed to about 50㎛.

The dot pattern R2 is formed to have a roughness on the lower surface of the light guide plate, is formed small in the light incident portion, and is formed densely toward the light receiving portion side. This is to emit a uniform amount of light to the upper side because the density of light incident from the light incident part is gradually lowered. In addition, the dot pattern 320 preferably has a radius of curvature R2 of 30 μm or less to minimize dot reflection.

The prism pattern 310 and the dot pattern 320 having the above structure do not exhibit a phenomenon such as a hot spot or a moire pattern, and thus exhibit excellent optical characteristics, and the characteristics gradually become worse when out of the above range.

Meanwhile, as illustrated in FIG. 2, a prism sheet 400 is stacked on the light guide plate 300 to efficiently concentrate and disperse light and to incident the light vertically with respect to an upper liquid crystal display panel (not shown). The prism sheets 410 and 420 according to the embodiment of the present invention may be stacked up and down, and the prism shapes formed on the upper surface of each sheet are disposed to be perpendicular to each other.

The prism shape of the upper surface of the prism sheet 400 has an angle α2 of 85 ° to 95 °, and is matted to prevent wet out. In addition, a diffusion type additive is added to the resin forming the prism sheet 400 so that light collides with the additive to be efficiently dispersed, and in the embodiment of the present invention, the additive so as to exhibit a haze value of 10% to 40%. Is added.

In the exemplary embodiment of the present invention, the light guide plate and the prism sheet having the above structure do not stack a separate diffusion sheet for improving the optical characteristics, thereby providing a slimmer backlight device while maintaining excellent optical characteristics.

8A to 8C illustrate optical characteristics of a backlight device using a light guide plate according to the related art and an exemplary embodiment of the present invention.

FIG. 8A is a photograph showing optical characteristics in a structure in which two prism sheets and two diffusion sheets are laminated on a light guide plate according to the prior art, and FIG. 8B shows two prism sheets in a light guide plate according to the related art. 8 is a photograph showing optical characteristics of a structure in which two prism sheets are laminated on a light guide plate according to an embodiment of the present invention. In an embodiment of the present invention, the distance P1 of the prism pattern 310 is 50 μm, the angle α1 of the peak is 100 °, the radius of curvature R1 is 10 μm, and the initial height D of the peak is 18. A pattern having a thickness was formed.

As shown, in the light guide plate according to the embodiment of the present invention, the coupling section due to the recycling effect is shortened significantly by the prism pattern on the upper surface, and thus the optical characteristic is excellent in appearance. It can be seen.

That is, the side dimming type backlight device to which the light guide plate 300 having the above configuration is applied can exhibit excellent optical characteristics while removing the diffusion sheet (50 in FIG. 1) stacked on the upper side, thereby simplifying the structure, efficiency of assembly, It has the same effect as slimming down the device.

The present invention has been described above with reference to one embodiment shown in the drawings, but those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom.

1 is an exploded perspective view of a side dimming backlight device according to the prior art;

2 is an exploded perspective view of a side dimming backlight device according to an embodiment of the present invention;

3 is a perspective view showing a light guide plate according to an embodiment of the present invention;

4 is a plan view showing a light guide plate according to an embodiment of the present invention;

5 is a bottom view of a light guide plate according to an embodiment of the present invention;

6 is a side cross-sectional view showing a detailed structure of a light guide plate according to an embodiment of the present invention;

7 is a front sectional view showing a detailed structure of a light guide plate according to an embodiment of the present invention;

8A to 8C illustrate optical characteristics of a backlight device using a light guide plate according to a related art and an embodiment of the present invention.

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

100: LED (light source) 200: reflector

300: light guide plate 400: prism sheet

310: prism pattern 320: dot pattern

Claims (4)

In the side lighting type backlight device in which a plurality of light emitting diode light sources 100 are arranged on one side of the light guide plate 300, On the upper surface of the light guide plate 300, in order to disperse and collect light incident from the light source 100 and to emit the light toward the upper side, the height is lowered from the light incident portion toward the light facing portion, and the vertices of the mountain have rounded prism patterns 310. Is formed in the direction of the light portion, On the lower surface of the light guide plate 300, a dot pattern 320 for scattering and dispersing light incident to the inside of the light guide plate and outputting the light to the upper surface of the light guide plate is formed closer to the light guide part, Only a pair of prism sheets (400) are stacked on the upper side of the light guide plate, side lighting type backlight device, characterized in that configured to improve the characteristics of the light emitted to the upper side. The method of claim 1, The prism pattern 310 has an angle α1 of 80 ° ≦ α1 ≦ 110 °, a radius of curvature R1 of 0 <R1 ≦ 0.9 * P1 with respect to the prism pattern interval P1, The maximum height D is formed with a length L of 30 mm or less so that the maximum height D is continuously reduced toward the light receiving part with D ≦ 0.5 * P1 with respect to the prism pattern spacing P1, The dot pattern 320 is a side dimming backlight device, characterized in that the radius of curvature (R2) is formed 0 <R2 ≤ 30㎛. The method according to claim 1 or 2, The prism sheet 400 has an angle α2 of an upper surface of 85 ° ≦ α2 ≦ 95 °, and has a matte treatment on the lower surface thereof to prevent wet out phenomenon. The method of claim 3, The prism sheet 400 is a side dimming backlight device, characterized in that the diffusion additive is added so that the haze has a value of 10% to 40%.

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