TWI596407B - Backlight unit - Google Patents

Description

Backlight unit

The present invention claims priority to Korean Patent Application No. 10-2010-0086258, filed on Sep. 3, 2010, which is hereby incorporated by reference.

The present invention relates to a backlight unit.

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 that includes a thinner light guide plate.

In one embodiment, a backlight unit includes: a light guide plate including a plurality of grooves; a plurality of side emitting type light emitting devices are respectively inserted into the grooves a printed circuit board (PCB) on which a side light emitting type light emitting device is disposed; and a reflection plate between the light guide plate and the printed circuit board.

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 cross-sectional view of a backlight unit, in accordance with an embodiment.

The backlight unit of the embodiment of the present invention comprises: a light guide plate 100, wherein a plurality of trenches 110 are formed; a plurality of side-emitting illumination devices 310 are respectively inserted in the trenches 110; and a printed circuit board 300 is disposed thereon The side light emitting type light emitting device 310; and a reflecting plate 320 are disposed between the light guiding plate 100 and the printed circuit board 300.

The light guide plate 100 may be formed of a transparent material. For example, the light guide plate 100 may be formed of one of an acrylic resin-based material, such as a thermoplastic resin (PMMA), a polyethylene terephthlate (PET). Resin, a polycarbonate (PC) resin, and a polyethylene naphthalate (PEN) resin.

The side-emitting type light-emitting device 310 may include light emitting diodes (LEDs).

The LED can be a colored LED capable of emitting at least one of red, blue, green, and white light, or can be an ultraviolet (UV) LED. For example, a colored LED can include a combination of red, blue, green, and white LEDs. The configuration of the color LEDs and the type of light can be varied within the technical scope of the embodiments of the present invention.

The side-emitting type light-emitting device 310 may be provided in a package form in which an LED is disposed.

The printed circuit board 300 provided with the side-emitting type light-emitting device 310 may be disposed under the light guide plate 100.

The printed circuit board 300 can be a metal core PCB (MCPCB), a FR-4 printed circuit board, a typical general printed circuit board, a flexible printed circuit (FPCB), or a Ceramic circuit board. However, the printed circuit board 300 is not limited thereto, but can be used as any other kind of printed circuit board within the technical scope of the embodiments of the present invention.

In the backlight unit of the present embodiment, the trenches 110 are uniformly formed on the bottom surface of the light guide plate 100, and the side light-emitting type light-emitting devices 310 are respectively inserted into the trenches 110.

The reflection plate 320 is disposed between the light guide plate 100 and the printed circuit board 300.

The reflection plate 320 may be formed of an alloy including silver or aluminum.

In addition, the adhesive layers 321, 322 may be disposed on the top side and the bottom side of the reflective plate 320 to bond the reflective plate 320 to the light guide plate 100 and the printed circuit board 300.

The adhesive layer 321 , 322 includes a first adhesive layer 321 between the light guide plate 100 and the printed circuit board 300 , and a second adhesive layer 322 between the printed circuit board 300 and the reflective plate 320 .

The adhesive layers 321, 322 may be formed of a transparent material such as an epoxy resin or a silicon-based resin.

A concave-convex microstructure 101 may be disposed on the bottom surface of the light guide plate 100 at the junction of the first adhesive layer 321 to enhance the light discharge efficiency of the light guide plate 100 when light is incident on the light guide plate 100.

The microstructure 101 is disposed on a region of the light guide plate 100 where the trench 110 is not formed, and the microstructure 101 is not deeper than the trench 110.

According to the backlight unit of the present embodiment, since the side-light-emitting type light-emitting devices 310 are respectively disposed in the trenches 110 of the light guide plate 100, the thickness of the light guide plate 100 can be reduced.

In the backlight unit of the present embodiment, since the trenches 110 are uniformly disposed along the light guide plate 100, and the side light emitting type light emitting devices 310 are respectively disposed in the trenches 110, the uniform light can be self-guided. 100 was released.

2 is a cross-sectional view showing a backlight unit according to another embodiment.

In the backlight unit of the embodiment, the light shielding reflection patterns 700 are disposed on a light emitting surface (top surface) of one of the light guide plates 100, corresponding to the grooves formed in the light guide plate 100. At slot 110, as shown in FIG.

The light-shielding reflective microstructures 700 are disposed on the light-emitting surface of the light guide plate 100, and the light beams emitted from the side-emitting light-emitting devices 310 in the trenches 110 are concentrated to generate hot spots.

That is, the light-shielding reflective microstructures 700 are arranged on the top surface of the light guide plate 100, and the partial light-shielding reflective microstructures 700 and the trenches 110 overlap along the light path of the light emitted from the side-emitting light-emitting device 310. Where.

The light-shielding reflective microstructures 700 can be white coated microstructures or metal microstructures.

In other words, in the backlight unit of the embodiment, the light-shielding reflective microstructures 700 are disposed on the light-emitting surface of the light guide plate 100, corresponding to the trenches 110 formed in the light guide plate 100, and the self-side illumination type light-emitting device 310. Where the emitted beams are concentrated to prevent light from converge there. Therefore, the backlight unit of the present embodiment can reduce the bright spots and avoid the situation of brightness irregularity.

In the backlight unit of the present embodiment, the light-shielding reflective microstructure 700 reflects the light emitted from the side-light-emitting type light-emitting device 310. Then, the reflected light advances along each path in the light guide plate 100 and is released to the outside of the light guide plate 100. Therefore, the uniformity of the light beam emitted from the light guide plate 100 can be improved.

3 is a cross-sectional view showing a comparative example of a backlight unit of another embodiment; FIG. 4 is a cross-sectional view showing a light advancement path of a comparative example of a backlight unit of another embodiment; A cross-sectional view of a light advancement path of a backlight unit of another embodiment will be described.

As shown in FIGS. 3 and 4, in the comparative example of the backlight unit of other embodiments, the light-shielding reflective microstructures 700 are not disposed on the top surface of the light guide plate 100.

In the comparative example, the light beam emitted from the side light-emitting type light-emitting device 310 is concentrated in a region close to the side-light-emitting type light-emitting device 310 after the light beam is advanced through the air layer and the light guide plate 100. Therefore, bright spots will occur in this area.

That is, as shown in FIG. 4, the light beams A and B emitted from the side light-emitting type light-emitting device 310 are incident on the light guide plate 100 via an air layer, and are released to the outside through a region K.

Therefore, the light emitted in the comparative example may have a problem of uneven brightness due to bright spots.

However, according to the backlight unit of other embodiments, since the light-shielding reflective microstructures 700 are disposed on the top surface of the light guide plate 100, the light beams A1 and A2 emitted from the side-light-emitting type light-emitting device 310 are advanced through an air layer and a guide. The light plate 100 is simultaneously refracted in the air layer and the light guide plate 100. Then, the light beams A1, A2 are reflected back to the light guide plate 100 by the light-shielding reflective microstructures 700.

That is, the light beams A1, A2 are not concentrated to a specific area of the light guide plate 100. Accordingly, when light is emitted from the backlight unit, the bright spots can be reduced, and brightness unevenness can be further prevented.

Since the reflective plate 320 (see FIG. 1) is disposed below the light guide plate 100, the light reflected from the light-shielding reflective microstructure 700 can be reflected again to the light guide plate 100.

In the following, another embodiment will be explained in conjunction with FIG. 6.

FIG. 6 is a cross-sectional view showing a backlight unit according to another embodiment.

In the backlight unit of the embodiment, the independent light-shielding reflective microstructures 700 are disposed on a light-emitting surface (top surface) of a light guide plate 100, corresponding to the trenches 110 formed in the light guide plate 100, as shown in the figure. 6 is shown.

The light-shielding reflective microstructures 700 are disposed on the light-emitting surface of the light guide plate 100, and the light beams emitted from the side-emitting light-emitting devices 310 in the trenches 110 are concentrated to generate bright spots.

That is, the light-shielding reflective microstructures 700 are arranged on the top surface of the light guide plate 100, and the partial light-shielding reflective microstructures 700 and the trenches 110 overlap along the light path of the light emitted from the side-emitting light-emitting device 310. Where.

The light-shielding reflective microstructures 700 can be white coated microstructures or metal microstructures.

A transparent protective layer 710 may be further disposed on the top surface of the light guide plate 100 to cover the light-shielding reflective microstructures 700. The transparent protective layer 710 may be formed of a transparent resin having a refractive index lower than that of the light guide plate 100.

In the backlight unit of the present embodiment, the light-shielding reflective microstructures 700 are disposed on the light-emitting surface of the light guide plate 100, corresponding to the grooves 110 formed in the light guide plate 100, and the light beams emitted from the side-light-emitting type light-emitting device 310 are Convergence to prevent light from gathering there. Therefore, the backlight unit of the embodiment can reduce the bright spots and avoid uneven brightness.

As described above, since the light-emitting device is disposed in the groove of the light guide plate, the thickness of the light guide plate can be reduced.

Further, in the backlight unit of the present invention, since the grooves are uniformly disposed along the light guide plate, and the light-emitting devices are respectively disposed in the grooves, uniform light can be released from the light guide plate.

In the backlight unit of the present invention, the light-shielding reflective microstructure is disposed on the light-emitting surface of the light guide plate, corresponding to the groove formed in the light guide plate and the light beam emitted from the side-light-emitting type light-emitting device being concentrated. To stop the light from gathering there. Therefore, the backlight unit can reduce the bright spots and avoid uneven brightness.

Further, in the backlight unit of the present invention, the light beam emitted from the side light-emitting type light-emitting device is reflected by the light-shielding reflective microstructure, and then the reflected light is advanced along each path in the light guide plate and released to the outside of the light guide plate. Therefore, the uniformity of the light beam emitted from the light guide plate can be improved.

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. For those skilled in the art, alternative uses will be apparent in addition to variations and modifications in parts and/or configurations.

100. . . Light guide

101. . . microstructure

110. . . Trench

300. . . A printed circuit board

310. . . Illuminating device

320. . . Reflective plate

321, 322. . . Adhesive layer

700. . . microstructure

710. . . The protective layer

A, B, A1, A2. . . beam

K. . . region

1 is a cross-sectional view showing a backlight unit according to an embodiment;

2 is a cross-sectional view showing a backlight unit according to another embodiment;

3 is a cross-sectional view showing a comparative example of a backlight unit of another embodiment;

4 is a cross-sectional view showing a light advancement path of a comparative example of a backlight unit of another embodiment;

5 is a cross-sectional view showing a light advancement path of a backlight unit of another embodiment;

FIG. 6 is a cross-sectional view showing a backlight unit according to another embodiment.

100. . . Light guide

101. . . microstructure

110. . . Trench

300. . . A printed circuit board

310. . . Illuminating device

320. . . Reflective plate

321, 322. . . Adhesive layer

Claims (14)

A backlight unit comprising: a light guide plate comprising a plurality of grooves; a plurality of side-emitting illumination devices respectively inserted in the grooves; and a printed circuit board on which the side-emitting illumination devices are disposed; a reflector between the light guide plate and the printed circuit board, and having a first opening region overlapping the trenches; a first adhesive layer on the printed circuit board and having the trenches And superposing one of the second open areas; a second adhesive layer on the reflective plate and having a third open area overlapping the plurality of grooves; and a plurality of light-shielding reflective microstructures disposed on the light guide plate On the light-emitting surface, corresponding to the trenches formed in the light-guiding plate, and the light-shielding reflective microstructures are separated from each other, wherein the light-shielding reflective microstructures do not overlap with the side-emitting light-emitting devices. The light-shielding reflective microstructures overlap the light paths of the light emitted from the side-emitting light-emitting devices, wherein the light guide plate, the first adhesive layer and the second adhesive layer are not overlapped with the sides hair Contacting light-emitting device. The backlight unit of claim 1, wherein the first to third openings The width of the mouth is the same as the width of each groove. The backlight unit of claim 2, wherein the width of the trenches is greater than the width of the side-emitting illumination devices. The backlight unit of claim 2, wherein the first and second adhesive layers are formed of a transparent material. The backlight unit of claim 1, wherein a recessed microstructure, a protruding microstructure, or a concave-convex microstructure is disposed on a bottom surface of the light guide plate, and an area between the trenches, and The depth of the microstructure is less than the depth of the trenches. The backlight unit of claim 1, wherein the side-emitting illumination devices are provided with an LED package. The backlight unit of claim 1, wherein the grooves are uniformly arranged on a bottom surface of the light guide plate. The backlight unit of claim 1, wherein the reflecting plate is formed of an alloy including silver or aluminum. The backlight unit of claim 2, wherein the first and second adhesive layers comprise an epoxy resin or a bismuth-based resin. The backlight unit of claim 1, wherein the light-shielding reflective microstructures respectively comprise a first portion and a second portion, the first portion not overlapping with the side-emitting illumination devices, The grooves overlap; the second part The sub-light-emitting device and the trenches are not overlapped; wherein the width of the first portion is smaller than the width of the second portion. The backlight unit of claim 1, wherein the light-shielding reflective microstructures are white coated microstructures or metal microstructures. The backlight unit of claim 1, wherein the light-shielding reflective microstructures are disposed on a top surface of the light guide plate, and a portion of the light-shielding reflective microstructures and the trenches are along The light paths of the light emitted from the side-emitting illumination device overlap. The backlight unit of claim 1, further comprising a transparent protective layer disposed on the light guide plate to cover the light-shielding reflective microstructures. The backlight unit of claim 13, wherein the transparent protective layer is formed of a material having a refractive index lower than a refractive index of the light guide plate.