KR20060093892A - Back light unit - Google Patents

Abstract

The present invention provides a backlight unit capable of minimizing the luminance unevenness between the light guide plate (bright part) corresponding to the light exit angle of the light source and the dark part (dark part) of the light guide plate deviated from the light exit angle of the light source. A light guide plate having a light source, an incident surface on which light is incident from the light source, and a lower surface on which first patterns are formed in one direction for scattering the incident light; The lower surface of the light guide plate includes second patterns formed in a direction perpendicular to the first patterns in the first patterns corresponding to the dark portions deviating from the emission angle of the light source.

Description

Backlight Unit {BACK LIGHT UNIT}

1 shows a typical backlight unit;

2 is a schematic perspective view of a backlight unit of the present invention using a point light source;

FIG. 3 is a schematic cross-sectional view of the backlight unit shown in FIG. 2; FIG.

4 and 5 show patterns formed on the bottom surface of the light guide plate;

6 is a cross-sectional view taken along the line a-a shown in FIG. 4;

7 and 8 illustrate another example of the second pattern;

9 is a view showing a horn-shaped protrusion formed on a dark portion of the light guide plate;

Explanation of symbols on the main parts of the drawings

110: light source

120: light guide plate

122: incident surface

130: first pattern

140: second pattern

The present invention relates to a backlight unit used in a liquid crystal display device.

In general, a liquid crystal display device is portable as one type of flat panel display element, and has been widely used recently because it has advantages of flat panel, thin film, low power consumption, and high image quality. However, since the LCD does not emit light and modulates the transmitted light only, a backlight unit should be provided at the rear of the LCD. The performance of the LCD is not only the LCD itself but the performance of the backlight used therein. Depends heavily on

BACKGROUND ART A backlight unit which is generally used includes a light source for generating light and a light guide plate for guiding the generated light to a liquid crystal display panel. The light source is positioned on one side (or both sides) of the light guide plate and is formed of a light emitting diode (LED). The lower portion of the backlight unit is provided with a reflective sheet for improving light efficiency by reflecting light leaked from the light guide plate toward the liquid crystal display panel.

The problem in the related art described above is that since the light emitting area of each light source (LED) 12 is small compared to the size of the light guide plate 10, the luminance unevenness of the light exit surface is likely to occur. That is, as shown in Fig. 1, since the LED 12 which is currently used has a light emission angle of about 70-90 ° as a point light source illuminant, the light emission line corresponding to the light emission angle of the LED is referred to as a broken line. A dark portion appears between the two portions, resulting in uneven luminance. This problem is mitigated, for example, by densely arranging a large number of LEDs, but since LEDs are expensive, they can be a major factor in increasing component costs of devices employing liquid crystal displays as LEDs increase.

SUMMARY OF THE INVENTION The present invention has been made to solve such a conventional problem, and an object thereof is a luminance non-uniformity phenomenon between a light guide plate (bright part) corresponding to an emission angle of a light source and a dark part (dark part) of the light guide plate deviated from the light emission plate. It is to provide a new type of backlight unit that can minimize the.

According to a feature of the present invention for achieving the above object, the backlight unit of the present invention; A light guide plate having an incident surface on which light is incident from the light source and a lower surface on which first patterns are formed in one direction for scattering the incident light; The lower surface of the light guide plate includes second patterns formed in a direction perpendicular to the first patterns in the first patterns corresponding to the dark portions deviating from the emission angle of the light source.

According to an embodiment of the present invention, each of the first patterns and the second patterns is formed of a V-cut, and the first patterns are formed perpendicular to the incident surface of the light guide plate.

According to the exemplary embodiment of the present invention, the lower surface of the light guide plate corresponding to the female part has a horn-shaped protrusion or groove formed by the first patterns and the second patterns.

According to a feature of the present invention for achieving the above object, the backlight unit of the present invention; A light guide plate having an incident surface on which light is incident from a light source and a bottom surface on which patterns formed for scattering incident light are formed; The patterns include a first prism pattern formed in a wrist included in the exit angle of the light source, and a second prism pattern formed in the dark part deviated from the exit angle of the light source.

According to an embodiment of the present invention, the first prism pattern includes first patterns formed in one direction.

According to an embodiment of the present invention, the second prism pattern includes a first pattern formed in one direction and a second pattern formed in a direction orthogonal to the first pattern on the first pattern.

According to an embodiment of the present invention, the second prism pattern includes a horn-shaped protrusion or groove.

For example, embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited by the embodiments described below. This embodiment is provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape of the elements in the drawings and the like are exaggerated to emphasize a clearer description.

Exemplary embodiments of the present invention will be described in detail with reference to FIGS. 2 to 9. In addition, in the drawings, the same reference numerals are denoted together for components that perform the same function.

2 is a schematic perspective view of a backlight unit of the present invention using a point light source. FIG. 3 is a schematic cross-sectional view of the backlight unit illustrated in FIG. 2. 4 and 5 illustrate patterns formed on a bottom surface of the light guide plate. 6 is a cross-sectional view taken along the line a-a shown in FIG. 4. 7 and 8 illustrate another example of the second pattern. 9 is a view showing a projection of a horn formed in the dark portion of the light guide plate.

2 to 6, the backlight unit 100 emits light toward the liquid crystal panel (not shown) that displays an image by guiding light generated from the light source 110 and light generated from the light source 110. It includes a light guide plate 120 for.

The light source 110 is provided in plurality along one side wall (incident surface) 122 of the light guide plate 120. Here, a light emitting diode (LED) is used as the light source 110. Compared with the fluorescent tubes used in the past, the light emitting diodes do not require any special mechanism such as a booster, are light in weight, compact, and do not use high frequency and high voltage. In addition, power control is easy, and low power consumption can be easily coped with. In particular, the light emitting diodes have a long lifespan, and in recent years, red, green, blue, mixed color, and white color have become possible. In the case of using a light bulb, the life is shortened, but it is inexpensive and there is a possibility that the replacement can be easily performed.

The light emitted from the light source 110 made of the light emitting diode has a strong straightness and proceeds with a predetermined exit angle. That is, since the light source 110 is a point light source, as shown in FIGS. 2 and 3, the light source 110 emits light in the azimuth angle range of 70-90 degrees (emission angle), and the light emitted from the light source 110. Is incident to the light guide plate 120 through the incident surface 122, and thus the light guide plate 120 includes a light (x) (bright portion) included in the exit angle of the light source 110 and a deviation from the exit angle of the light source. A dark portion y (a portion darker than the list) is generated.

The present invention can minimize the luminance non-uniformity phenomenon between the light guide plate (bright portion) (x) of the light guide plate corresponding to the exit angle of the light source 110 and the dark portion (dark portion) (y) of the light guide plate deviated from the exit angle of the light source. It is characterized by having a light guide plate in which patterns are formed.

The light guide plate 120 has first and second patterns 130 and 140 formed on the bottom thereof to uniformly emit light incident from the light source 110 to the light exit surface 124.

The first patterns 130 are formed in one direction (the direction perpendicular to the incident surface of the light guide plate) on the entire bottom surface 123 of the light guide plate 120, and the second patterns 140 are formed in the first pattern 130. It is formed in a direction perpendicular to the field. It is important to note that the second patterns 140 are formed only on the first patterns 130 corresponding to the dark portions y, which are areas outside the emission angle of the light source 110. In other words, the bottom surface 123 of the light guide plate 120 is characterized in that the pattern formed in the recess (x) and the pattern formed in the dark portion (y) deviating from the emission angle of the light source 110 is different. . The pattern formed in the roll may be formed of the first patterns 130 of the V-cut simply formed in one direction, and the patterns formed in the female part may be the first pattern 130 and the second pattern 140 of the V-cut. ) May be orthogonal to each other. Thus, since the first pattern 130 and the second pattern 140 are formed in the dark portion away from the emission angle of the light source, more scattering occurs in the dark portion than the bright portion, thereby overcoming the luminance difference with the bright portion.

In the present embodiment, the shape of each of the first patterns or the second patterns is shown as a V-cut, but is not limited thereto, and the U-shaped groove 132 as shown in FIGS. The tapered groove 134 may be embossed or engraved.

On the other hand, the second pattern 140 may be formed at regular intervals in the arm portion, as shown in Figure 9, the second pattern 140 may be continuously densely formed. When the second patterns 140 are continuously densely formed, the quadrangular pyramid-shaped protrusions 142 may be formed by the first patterns 130 and the second patterns 140.

For example, in the present embodiment, the light guide plate 120 has the same thickness, but may be formed in a tapered form to adjust the uniformity of luminance.

For reference, the transparent material forming the light guide plate 120 may be made of an inorganic transparent material such as acrylic resin, polycarbonate resin, amorphous polyolefin resin, inorganic transparent material such as glass, or a composite thereof, injection molding, thermosetting resin, light It is formed by a method such as bonding a film or a resin layer on a reinforced resin, an etching, a transparent resin or a glass flat plate.

In the above, the configuration and operation of the backlight unit according to the present invention is shown according to the above description and drawings, but this is only an example, and various changes and modifications are possible without departing from the technical spirit of the present invention. to be.

According to the present invention, by additionally forming the second patterns in the dark portion of the light guide plate is less brightness, it is possible to increase the reflection surface and the light diffusion efficiency according to the increase in the internal area of the pattern on the dark portion, which is the It brings the effect of improving the brightness while improving the viewing angle. Therefore, it is possible to minimize the luminance non-uniformity phenomenon between the light guide plate (bright part) corresponding to the emission angle of the light source and the dark part (dark part) of the light guide plate deviated from the light emission plate.

Claims (9)

In the backlight unit: Light source; A light guide plate having an incident surface on which light is incident from the light source and a lower surface on which first patterns are formed in one direction for scattering the incident light; The lower surface of the light guide plate is a backlight unit, characterized in that the first patterns formed in the dark portion deviated from the emission angle of the light source includes a second pattern formed in a direction orthogonal to the first patterns.  The method of claim 1, And the first patterns are formed perpendicular to the incidence surface of the light guide plate. The method of claim 2, And each of the first patterns and the second patterns is formed of a V-cut. The method of claim 2, The lower surface of the light guide plate corresponding to the dark portion is a backlight unit, characterized in that the horn-shaped projections or grooves are formed by the first patterns and the second patterns. In the backlight unit: Light source; A light guide plate having an incident surface on which light is incident from the light source and a bottom surface on which patterns are formed for scattering incident light; The patterns may include a first prism pattern formed in a roll included in an emission angle of the light source, and a second prism pattern formed in a dark portion deviating from the emission angle of the light source.  The method of claim 5, The second prism pattern includes a first pattern formed in one direction and a second pattern formed on the first pattern in a direction orthogonal to the first pattern. The method of claim 6, The first prism pattern comprises a first pattern formed in one direction. The method of claim 6, The second prism pattern includes a horn-shaped protrusion or groove. The method according to claim 6 or 7, And each of the first patterns and the second patterns is formed of a V-cut.

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