TWI450001B - Backlight unit and method for manufacturing the same - Google Patents

Description

Backlight unit and method of manufacturing same

The present invention claims priority to Korean Patent Application No. 10-2010-0086260, filed on Sep. 3, 2010, which is hereby incorporated by reference.

The present invention relates to a backlight unit and a method of fabricating the same.

Cold cathode fluorescent lamps are widely used as backlight sources for LCDs due to their low price and easy assembly. However, cold cathode fluorescent lamps also have disadvantages such as mercury-related environmental problems, low reaction time, and insufficient color reproduction ability.

Due to the above drawbacks of cold cathode fluorescent lamps, light emitting diodes (LEDs) are used as backlight sources.

Recently, many researches on backlight units using LEDs as light sources have been underway, and the production of backlight units in this configuration has also increased significantly.

The backlight unit can be classified into an edge type backlight unit and a direct type backlight unit. In the edge-lit backlight unit, light is incident on one side of a light guide plate, and is guided to a panel via a top surface of the light guide plate.

In the direct type backlight unit, an LED is disposed on a back side of one of the diffusion sheets, and light emitted from the LED is supplied to a panel via the diffusion sheet.

Although the edge-lit backlight unit can be easily fabricated into a thin and light shape, it is difficult to ensure light uniformity in the case where the size of the LCD panel is large.

On the other hand, although the direct type backlight unit can be easily fabricated into a large size, the direct type backlight unit is difficult to be made thin due to the distance between an LED and a diffusion sheet.

Embodiments of the present invention provide a backlight unit for preventing local concentrated illumination of a light guide plate.

In one embodiment, a backlight unit includes: a light guide plate, wherein the light guide plate is formed with a plurality of grooves; and a plurality of side emitting type light emitting devices are respectively inserted in the grooves And a plurality of optical path shift layers disposed in the trenches to shift optical paths of the light emitted by the edge light-type light-emitting devices.

In another embodiment, a backlight unit includes: a light guide plate, wherein the light guide plate is formed with a plurality of openings; a plurality of side light type light-emitting devices are respectively inserted in the openings; and a plurality of optical path offset layers An optical path configured to seal the openings and to shift light emitted from the edge-lit light-emitting devices.

One or more embodiments of the invention are described in detail in the following figures and description. Other features can be found in the drawings and description of the invention, as well as in the scope of the claims.

In the following, the disclosure and examples of the present invention will be described and illustrated in detail in accordance with the embodiments of the invention.

1 is a schematic cross-sectional view of a backlight unit in accordance with an embodiment.

A backlight unit of the embodiment includes: a light guide plate 100, wherein a plurality of trenches 110 are formed in the light guide plate; and a plurality of side emitting type light emitting devices 310 are respectively inserted in the trenches 110; and a plurality of optical path shift layers 200 disposed in the trenches 110 to shift the optical path of the light emitted by the edge-type light-emitting devices 310.

The light guide plate 100 may be formed of a transparent material. For example, the light guide plate 100 can be made of, for example, polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), polycarbonate (PC), and polynaphthalene dicarboxylic acid. It is formed by one of acrylic resin-based materials such as polyethylene naphthalate (PEN).

The edge light type light emitting device 310 may include a light emitting diode.

The light emitting diode may be a color light emitting diode, and may emit at least one of red light, blue light, green light, and white light, or may be an ultraviolet light emitting diode. For example, the color light emitting diode may include a combination of light emitting diodes such as red, blue, green, and white. The arrangement of the color light-emitting diodes and the kind of the color light-emitting diode light can be changed within the technical scope of the present invention.

A printed circuit board 300 provided with the edge type light-emitting device 310 is disposed below the light guide plate 100.

The printed circuit board 300 can be a metal core printed circuit board, a FR-4 printed circuit board, a general printed circuit board, a flexible printed circuit board, or a ceramic printed circuit board. However, the printed circuit board 300 is not limited thereto, but may be any other kind of printed circuit board within the technical scope of the embodiment of the present invention.

Furthermore, in the backlight unit of the present embodiment, grooves (110) are formed on the bottom surface of the light guide plate 100 to receive the side light type light-emitting device 310, and the optical path offset layers 200 are disposed in the trench 110. On the inside wall.

The optical path of the light emitted from the edge type light-emitting device 310 is biased (i.e., changed) at the optical path offset layer 200, and then the light is incident on the light guide plate 100. Thereafter, the light is guided to the outside by the light guide plate 100.

At this time, the light whose optical path is deflected at the optical path offset layer 200 is uniformly distributed through the light guide plate 100, and then guided to the outside. Therefore, the light emitted from the light guide plate 100 does not cause a hotspot, and thus luminance unevenness is reduced.

That is, in the backlight unit of the present embodiment, the optical path shifting layer 200 is disposed in the trench 110, which is where the edge light type light emitting device 310 is inserted, thereby changing the optical path of the light emitted from the edge light type light emitting device 310. . This prevents local concentrated illumination of the light guide plate 100. Therefore reducing uneven brightness

The optical path shifting layer 200 may be formed of, for example, an acryl-containing resin and a silicon-containing resin.

The optical path offset layer 200 may have a different refractive index than the light guide plate 100. The light emitted by the edge type light-emitting device 310 is incident on the optical path offset layer 200 through the air layer and is refracted in the optical path offset layer 200. In this manner, the optical path of the light emitted from the edge-light type light-emitting device 310 is changed.

The refractive index of the optical path offset layer 200 may be greater than or smaller than the refractive index of the light guide plate 100.

Fig. 4 is a schematic cross-sectional view for explaining a light transmission path in the backlight unit of the embodiment.

As shown in FIG. 2, in the comparative example of the backlight unit of the present invention, the optical path offset layer is not disposed in the trench 110 where the edge light type light emitting device 310 is inserted.

In the comparative example, when the light emitted by the edge-light type light-emitting device 310 passes through the air layer and the light guide plate 100, the light is concentrated in a region close to the side-light type light-emitting device 310. This will cause a hotspot.

That is, as shown in FIG. 3, the light rays A and B emitted from the side light type light-emitting device 310 pass through an air layer and are incident on the light guide plate 100 and are emitted to the outside through a region (K).

Therefore, the light emitted from the comparative example has uneven brightness due to bright spots.

However, in the backlight unit of the embodiment, since the optical path offset layers 200 are disposed on the trenches 110 of the light guide plate 100, the light rays A1 and B1 emitted from the edge light type light-emitting device 310 are transmitted through an air layer. And refracted in the optical path offset layer 200. That is, the optical paths of the rays A1 and B1 are deflected at the optical path offset layer 200, and thus the rays A1 and B1 are not concentrated in one region of the light guide plate 100 as shown in FIG.

That is, when the light rays A1 and B1 are emitted through the light guide plate 100, the light rays A1 and B1 are not concentrated on a specific region of the light guide plate 100. According to this, when light is emitted from the backlight unit, the bright spot can be reduced, and thus unevenness in brightness can be prevented.

5 is a partial schematic cross-sectional view of a backlight unit according to a first embodiment, and FIG. 6 is a partial schematic cross-sectional view of the backlight unit according to the second embodiment.

In the backlight unit of the first embodiment, as shown in FIG. 5, the optical path offset layers 211, 212 are disposed in a partial region of the trench 110 of the light guide plate 100.

That is, the optical path offset layers 211, 212 are disposed in predetermined regions of the trench 110 of the light guide plate 100. For example, the optical path offset layers 211, 212 may be coated on a predetermined area of the inner wall of the trench 110 of the light guide plate 100.

The predetermined area of the trench 110 of the light guide plate 100 may be in a partial region of the trench 110. For example, the predetermined area of the trench 110 may be an inner wall region of the trench 110 that is separated from each other.

For example, the optical path offset layers 211, 212 may include corners where the trenches 110 face each other, as shown in FIG.

As described above, the optical path offset layers 211, 212 are disposed in a partial region of the trench 110 of the light guide plate 100. However, the positions of the optical path offset layers 211, 212 are not limited to those positions as shown in FIG. That is, the optical path offset layers 211, 212 can be disposed at any position as long as the brightness unevenness of the light emitted by the bright spot and the backlight unit can be reduced.

In the backlight unit of the second embodiment, as shown in FIG. 6, an uneven pattern 201 is formed on the optical path shift layer 200.

The microstructures 201 can change the optical path of the light emitted by the edge-lit illuminators 310. That is, the light may have different scattering depending on the shape of the microstructure 201, and thus when light is emitted from the backlight unit, the optical path has various changes to reduce the bright spot.

FIG. 7 is a partial schematic cross-sectional view showing a backlight unit according to a third embodiment.

In the backlight unit of the third embodiment, beads 220 are dispersed in the optical path shift layer 200.

The beads 220 irregularly reflect the light emitted from the side light type light-emitting device 310, so that partial concentrated light emission of the light guide plate 100 can be prevented. So reduce the bright spots.

The beads 220 may be formed of at least one of acryl, silicon, glass, and polystyrene.

8A to 8C are partial schematic cross-sectional views showing a backlight unit according to a fourth embodiment, and Fig. 9 is a partial schematic cross-sectional view showing the backlight unit according to the fifth embodiment.

The backlight unit of the fourth embodiment may include: a light guide plate 100, wherein a plurality of openings 111 are formed in the light guide plate; a plurality of edge light type light-emitting devices 310 are respectively inserted in the openings 111; and an optical path is offset The layer 200 seals the openings 111 and changes the optical path of the light emitted by the side-lighting device 310.

Since the openings 111 of the light guide plate 100 are sealed by the optical path offset layer 200, the light emitted from the side light type light-emitting device 310 is transmitted to the outside through the optical path shift layer 200 or the light guide plate 100.

Referring to FIG. 8A, the optical path offset layer 200 may be spaced apart from the edge light type light emitting device 310, and thus an air layer may be formed between the optical path shift layer 200 and the edge light type light emitting device 310.

Alternatively, the optical path shifting layer 200 may be in contact with the edge light type light emitting device 310, and thus the air layer is not formed between the edge light type light emitting device 310, the optical path shifting layer 200, and the light guide plate 100.

In this case, the optical path offset layer 200 may partially cover the edge light type light emitting device 310, as shown in FIG. 8B, or all of the side light type light emitting devices 310 as shown in FIG. 8C.

Referring to FIG. 9, the backlight unit of the fifth embodiment may include: a light guide plate 100, wherein a plurality of trenches 110 are formed in the light guide plate; and a plurality of edge light-type light-emitting devices 310 are respectively inserted in the trenches 110; And an optical path offset layer 200 covers the edge light type light emitting device 310 and changes the optical path of the light emitted by the side light type light emitting device 310. Referring to FIG. 9, the optical path offset layer 200 covers the surface of the edge light type light emitting device 310 and is spaced apart from the sidewall of the trench 110 of the light guide plate 100 by a predetermined distance, so that an air layer can be formed on the optical path offset layer 200 and Between the light guide plates 100.

10A to 10D are schematic cross-sectional views explaining a method of manufacturing a backlight unit according to an embodiment.

According to the backlight unit manufacturing method of this embodiment, first, a plurality of edge-light type light-emitting devices 310 are disposed on a printed circuit board 300 as shown in FIG. 10A.

Next, a light guide plate 100 is prepared, wherein the light guide plate 100 is formed with a plurality of grooves 110 (see FIG. 10B).

Next, the optical path shifting layer 200 is formed in the trench 110 of the light guide plate 100 to change the optical path of the light emitted from the side light type light emitting device 310 (see FIG. 10C).

At this time, the optical path shifting layer 200 may be formed on the entire inner wall of the trench 110 as shown in FIG. 1, or in a partial region of the inner wall of the trench 110 as shown in FIG. 5. In the latter case, the optical path offset layer 200 may be formed on a corner where the inner walls of the trench 110 face each other. Further, the optical path offset layer 200 may have an uneven surface as shown in FIG. 6.

The optical path offset layer 200 can be formed by one of the materials mentioned above.

Next, the light guide plate 100 is aligned with the printed circuit board 300, and thus the side light type light-emitting device 310 can be inserted into the groove 110 of the light guide plate 100 (refer to FIG. 10D).

When or after the light guide plate 100 is aligned with the printed circuit board 300, a fixed process such as a coupling or bonding process is performed to fix the light guide plate 100 to the printed circuit board 300.

11 is a partial schematic cross-sectional view showing a backlight unit according to a sixth embodiment.

In the backlight unit of the sixth embodiment, a pattern 101 is disposed on a light guide plate 100 facing a printed circuit board 300 to emit light to the light guide plate 100.

As shown in FIG. 11, the backlight unit includes: an optical path offset layer 200 on the inner wall of the trench 110 formed on the light guide plate 100; and a light reflecting plate 320 on the bottom surface of the light guide plate 100.

That is, the pattern 101 is formed on the light guide plate 100, and the reflection plate 320 is disposed on the bottom surface of the light guide plate 100. Therefore, the light incident to the light reflecting plate 320 and the light reflected from the light reflecting plate 320 to the light guiding plate 100 can be dispersed in the pattern 101. Therefore, light can be emitted from the backlight unit without a bright spot.

As described above, in the backlight unit of the embodiment, the optical path shifting layer is disposed in the groove in which the side light type light emitting device is inserted, thereby changing the optical path of the light emitted from the side light type light emitting device. This prevents local concentrated illumination of the light guide plate, thus reducing uneven brightness.

Further, beads may be dispersed in the optical path shifting layer to irregularly reflect light emitted from the edge-light type light-emitting device, thereby preventing local concentrated light emission of the light guide plate. Thereby reducing the bright spots.

While the invention has been described with respect to the embodiments of the embodiments of the present invention More particularly, various variations and modifications are possible in the component parts and/or arrangements of the claimed combinations. Alternative uses will be apparent to those skilled in the art, in addition to variations and modifications in parts and/or configurations.

100. . . Light guide

101. . . microstructure

110. . . Trench

111. . . Opening

200. . . Optical path offset layer

201. . . microstructure

211. . . Optical path offset layer

212. . . Optical path offset layer

220. . . Bead

300. . . A printed circuit board

310. . . Sidelight type illuminating device

320. . . Reflector

A, B. . . Light

A1, B1. . . Light

K. . . region

FIG. 1 is a schematic cross-sectional view of a backlight unit according to an embodiment.

2 is a schematic cross-sectional view showing a comparative example of the backlight unit of the embodiment.

Fig. 3 is a schematic cross-sectional view for explaining a light transmission path in a comparative example of the backlight unit of the embodiment.

Fig. 4 is a schematic cross-sectional view for explaining a light transmission path in the backlight unit of the embodiment.

FIG. 5 is a partial schematic cross-sectional view showing a backlight unit according to the first embodiment.

FIG. 6 is a partial schematic cross-sectional view showing a backlight unit according to a second embodiment.

FIG. 7 is a partial schematic cross-sectional view showing a backlight unit according to a third embodiment.

8A to 8C are partial schematic cross-sectional views showing a backlight unit according to a fourth embodiment.

FIG. 9 is a partial schematic cross-sectional view showing a backlight unit according to a fifth embodiment.

10A through 10D are schematic cross-sectional views explaining a method of fabricating a backlight unit according to an embodiment.

11 is a partial schematic cross-sectional view showing a backlight unit according to a sixth embodiment.

100. . . Light guide

110. . . Trench

200. . . Optical path offset layer

300. . . A printed circuit board

310. . . Sidelight type illuminating device

Claims (16)

A backlight unit includes: a light guide plate, wherein the light guide plate is formed with a plurality of grooves; a plurality of side light type light-emitting devices are respectively inserted in the grooves; and a plurality of optical path offset layers are formed on the light-emitting plates The outer surface of the edge-light type illuminating device changes the optical path of the light emitted by the side-light-type illuminating devices. The backlight unit of claim 1, wherein the optical path offset layers are formed of a resin. The backlight unit of claim 1, wherein the optical path offset layers have a refractive index different from a refractive index of the light guide plate. The backlight unit of claim 1, wherein the edge light type light emitting devices are light emitting diodes. The backlight unit of claim 1, wherein the uneven patterns are disposed on the optical path offset layers. The backlight unit of claim 1, wherein beads are distributed in the optical path offset layers. The backlight unit of claim 6, wherein the beads are formed of at least one of acryl, silicon, glass, and polystyrene. The backlight unit of claim 1, wherein the edge light type light emitting devices are disposed on a printed circuit board, and a light reflecting plate is disposed between the light guide plate and the printed circuit board. The backlight unit of claim 8, wherein an uneven pattern is disposed on a surface of the light guide plate that is in contact with the light reflecting plate. A backlight unit includes: a light guide plate, wherein the light guide plate is formed with a plurality of openings; a plurality of side light type light-emitting devices are respectively inserted in the openings; and a plurality of optical path offset layers are disposed to seal the openings And changing an optical path of the light emitted by the edge light type light emitting devices, wherein the optical path offset layers have a refractive index different from a refractive index of the light guide plate. The backlight unit of claim 10, wherein an air layer is formed between the optical path offset layer and the edge light type light emitting devices. The backlight unit of claim 10, wherein the optical path offset layers are disposed to cover a partial region of the edge light type light emitting devices. The backlight unit of claim 10, wherein the edge light type light emitting devices are light emitting diodes. The backlight unit of claim 10, wherein the optical path offset layers are formed of a resin. A method for manufacturing a backlight unit, the method comprising: setting a plurality of edge-light type light-emitting devices on a printed circuit board; preparing a light guide plate, wherein a plurality of grooves are formed in the light guide plate; Forming a plurality of optical path offset layers on an outer surface of the edge light type light emitting devices to change an optical path of light emitted by the edge light type light emitting devices; and aligning the light guide plate and the printed circuit board to the sides The light emitting device is inserted into the grooves of the light guide plate. The manufacturing method of claim 15, wherein the forming of the optical path offset layers is performed such that the optical path offset layers are formed in a partial region of the inner walls of the trenches.