TWI509323B - Backlight unit - Google Patents

Description

Backlight unit

The present invention claims priority to Korean Patent Application No. 10-2010-00849595, filed on Aug. 31, 2010. This is incorporated herein 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 the LED and the diffusion sheet.

Embodiments of the present invention provide a backlight unit that avoids local light convergence of a light guide plate.

In one embodiment, a backlight unit includes: a light guide plate including a plurality of grooves; a plurality of side light-emitting type light-emitting devices respectively disposed in the trenches; and an optical path variation portion disposed on the trenches Between the optical paths of the light emitted by the side-emitting illumination devices. .

The trenches may be uniformly disposed along the light guide plate.

The trenches may be formed on one of the bottom sides of the light guide plate.

The optical path changing portion may be an optical path changing groove formed between the top sides of the light guide plate or the bottom sides of the light guide plate.

The optical path changing portion may be disposed between the trenches and penetrate the light guide plate.

The backlight unit may further include a resin layer disposed in at least a portion of the optical path variation portion, wherein the refractive index of the resin layer may be different from the refractive index of the light guide plate.

The resin layer may also be disposed on one of the top sides or one of the bottom sides of the light guide plate.

Beads may be dispersed in the resin layer.

The beads may include at least one of acryl, ruthenium, glass, and polystyrene.

The backlight unit may further include a resin layer disposed on at least a portion of the opening penetrating the light guide plate.

The backlight unit may further include a resin layer disposed on an inner wall of the trenches, wherein a refractive index of the resin layer may be different from a refractive index of the light guide plate.

The optical path changing portion may be an optical path changing groove formed on a bottom side of the light guide plate, and the side light emitting type light emitting device may be disposed on a printed circuit board (PCB); The hole may be formed at a position communicating with the optical path changing groove via the printed circuit board.

A coupling portion can be inserted into the optical path changing groove formed on the bottom side of the light guide plate and the through hole to couple the light guide plate to the printed circuit board.

The side-emitting type light-emitting device can be provided in the form of a package in which an LED is provided.

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 showing a backlight unit according to a first embodiment; FIG. 2 is a cross-sectional view showing a backlight unit according to a second embodiment; FIG. 3 is a diagram showing a third embodiment according to a third embodiment; There is a cross-sectional view of the backlight unit.

The backlight unit of the embodiment of the invention includes: a light guide plate 100, wherein a plurality of grooves 110a, 110b are formed; a plurality of side-emitting illumination devices 310a, 310b; and an optical path varying portion disposed between the trenches 110a, 110b to change an optical path of the light emitted by the side-emitting illumination devices 310a, 310b.

In the backlight unit of the embodiment of the present invention, the optical path of the light emitted from the side-light-emitting type light-emitting devices 310a and 310b is changed in the optical path changing portion, and then incident on the light guide plate 100. After that, the light is emitted to the outside via the light guide plate 100.

The side-emitting type light-emitting devices 310a, 310b may be provided in the form of a package in which an LED is disposed.

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 devices 310a, 310b may be disposed on a printed circuit board 300.

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 may be any other kind of printed circuit board that can be within the technical scope of the embodiments of the present invention.

A reflecting member (not shown) may be disposed on the top side of the printed circuit board 300 to reflect light from the side-emitting type light-emitting devices 310a, 310b in an upward direction.

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 acryl resin materials, such as polymethylmethacrylate (PMMA), a polyethylene terephthlate (PET) resin. , a polycarbonate (PC) resin, and a polyethylene naphthalate (PEN) resin.

The trenches 110a, 110b may be formed on the bottom side of the light guide plate 100.

The grooves 110a and 110b may be uniformly disposed on the light guide plate 100.

The optical path varying portion may be provided between the side light-emitting type light-emitting devices 310a and 310b on the top side or the bottom side of the light guide plate 100.

The top side of the light guide plate 100 is a light emitting surface; the light emitted from the side light emitting type light emitting devices 310a, 310b can be conducted to the outside through this. The bottom side of the light guide plate 100 is a surface facing the printed circuit board 300, on which the side light-emitting type light-emitting devices 310a, 310b are supported.

As shown in FIG. 1, the optical path changing portion may be one of the following: an optical path changing groove 115a is formed on the top side of the light guide plate 100, as shown in FIG. 1, and an optical path changing groove 115b is formed on The bottom side of the light guide plate 100 is as shown in FIG. 2; and an opening 116 is formed through the top side and the bottom side of the light guide plate 100, as shown in FIG.

The optical path variation grooves 115a and 115b formed on the top side and the bottom side of the light guide plate 100 have a depth smaller than the thickness of the light guide plate 100 but larger than 1/2 of the thickness of the light guide plate 100.

That is, if the depth of the optical path changing grooves 115a, 115b is equal to the thickness of the light guide plate 100, the optical path changing grooves 115a, 115b may be openings that penetrate the top side and the bottom side of the light guide plate 100 (see the figure). Opening 116 in 3). That is, the groove cannot be defined.

If the depth of the optical path changing grooves 115a, 115b is less than 1/2 of the thickness of the light guide plate 100, the light emitted from one of the side light emitting type light emitting devices, such as the side light emitting type light emitting device 310a, can be transmitted to The adjacent side-emitting type light-emitting device 310b can superimpose the light emitted from the side-light-emitting type light-emitting device 310a and its adjacent side-light-emitting type light-emitting device 310b, thereby generating a hot spot.

That is to say, the propagation path of the light can be completely changed at the optical path variation portion, and thus the light can be transmitted to the outside without being locally concentrated on the light guide plate 100. Therefore, it is possible to prevent the hot spot from being generated in the light guide plate 100, and further, it is possible to reduce the brightness irregularity.

As described above, in the backlight unit of the embodiment of the invention, the optical path varying portion is disposed between the grooves in which the side-emitting type light-emitting devices are inserted to change the light output from the side-side light-emitting type light-emitting device. The optical path, thereby preventing the light from being locally concentrated on the light guide plate. Thereby, the unevenness of brightness can be reduced.

4 is a cross-sectional view showing a light propagation path of a backlight unit in a comparative example of the present invention; and FIG. 5 is a cross-sectional view showing a light propagation path in a backlight unit according to an embodiment of the present invention.

As shown in FIG. 4, in a comparative example of a backlight unit of the present invention, an optical path varying portion is not provided between the grooves 110a and 110b in which the side light-emitting type light-emitting devices 310a and 310b are inserted in the light guide plate 100.

In the comparative example, one of the light beams A emitted from the side-emitting type light-emitting device 310a can be propagated to the light guide plate 100 toward the groove 110b provided with the adjacent side-light-emitting type light-emitting device 310b, and the light beam A can be in the groove The 110b is refracted to the outside through a specific area K of one of the light guide plates 100.

In addition, one of the light beams B emitted from the side-emitting light-emitting device 310b can be output to the outside through a specific region K of the light guide plate 100.

In this case, since the light beam A emitted from the side light-emitting type light-emitting device 310a and the light beam B emitted from the adjacent side-light-emitting type light-emitting device 310b are concentrated on a specific region K of the light guide plate 100, it may be formed. A hot spot.

Therefore, in the comparative example, the emitted light may have uneven brightness due to the hot spot.

However, referring to FIG. 5, in a backlight unit according to an embodiment of the present invention, an optical path changing portion such as an optical path changing groove 115a is formed between the side light-emitting type light-emitting devices 310a and 310b on the top side of a light guide plate 100. . Therefore, the optical path from the side-light-emitting type light-emitting device 310a emitting one of the light beams A is changed at the optical path changing groove 115a so that the light beam A can emit a light beam along with the self-side-side light-emitting type light-emitting device 310b. The path of the optical path of B is output to the outside.

That is, in the backlight unit of one embodiment of the present invention, the light beams emitted from the side-emitting type light-emitting devices 310a, 310b are not concentrated in one of the light guide plates 100. In a specific area, it is possible to avoid the hot spot and uneven brightness of the light emitted by the backlight unit.

6 is a partial cross-sectional view showing a backlight unit according to a fourth embodiment; FIG. 7 is a partial cross-sectional view showing a backlight unit according to a fifth embodiment; FIG. 8 is a sixth embodiment according to a sixth embodiment. A partial cross-sectional view of a backlight unit is shown.

In the backlight unit of the fourth and fifth embodiments, a resin layer 230 is disposed in at least a portion of an optical path changing groove 115a, wherein the optical path changing groove 115a is provided in a light guide plate 100. As an example of an optical path variation.

The resin layer 230 refracts light emitted from the side-light-emitting type light-emitting device 310a to change the optical path of the light so as not to be combined with light emitted from the side-light-emitting type light-emitting device 310b. Therefore, light is not concentrated on a specific area of the light guide plate 100.

In an embodiment, an optical path changing portion may be one of the following: an optical path changing groove 115a is formed on the top side of the light guide plate 100; and an optical path changing groove (not shown) is formed on the light guide plate 100. a bottom side; and an opening (not shown) formed through the top side and the bottom side of the light guide plate. The resin layer 230 may be disposed in an inner portion of all or a part of the optical path variation portion.

For example, as shown in FIG. 6, the resin layer 230 may be disposed in one portion of the optical path variation groove 115a, wherein the optical path variation groove 115a is an example of an optical path variation.

In addition, as shown in FIG. 7, the resin layer 230 may also be disposed on the top side or the bottom side of the light guide plate 100.

Alternatively, in the backlight unit of the sixth embodiment shown in FIG. 8, the resin layer 230 is provided in the grooves 110a and 110b, and the side light-emitting type light-emitting devices 310a and 310b are disposed.

The refractive index of the resin layer 230 may be different from the refractive index of the light guide plate 100. That is, the refractive index of the resin layer 230 is larger or smaller than the refractive index of the light guide plate 100.

Figure 9 is a partial cross-sectional view showing a backlight unit according to a seventh embodiment.

In the backlight unit of the seventh embodiment, the beads 220 are dispersed in a resin layer 230.

The beads 220 irregularly reflect the light emitted by the side-emitting light-emitting devices 310a and 310b to prevent the light emitted from the light guide plate 100 from being locally concentrated. Therefore, hot spots can be reduced.

For example, most of the light emitted by the side-emitting type light-emitting device 310a can be irregularly reflected by the beads 220 dispersed in the resin layer 230.

The bead 220 may include at least one of acryl, ruthenium, glass, and polystyrene.

Figure 10 is a partial cross-sectional view showing a backlight unit according to an eighth embodiment.

In the case where an optical path changing groove 115b is formed as an optical path changing portion, the optical path changing groove 115b can be used to connect a light guide plate 100. Connected to a printed circuit board 300 provided with side-emitting illumination devices 310a, 310b.

For example, as shown in FIG. 10, a through hole 320 may be formed in the printed circuit board 300 to communicate with the optical path changing groove 115b, and a coupling part such as a screw may be inserted into the screw. The through hole 320 of the printed circuit board 300 and the optical path changing groove 115b of the light guide plate 100 are coupled to the printed circuit board 300 and the light guide plate 100.

To this end, a threaded groove may be formed on the wall of the through hole 320 of the printed circuit board 300 and the optical path changing groove 115b of the light guide plate 100, and the coupling portion may be coupled to the threaded groove.

Since the printed circuit board 300 and the light guide plate 100 are coupled to each other using the optical path variation grooves 115b formed in the light guide plate 100 to reduce hot spots, an additional coupling portion or material such as an adhesive is not required, thereby Reduce the thickness of the backlight unit.

As described above, according to the embodiment of the present invention, the optical path varying portion is disposed between the grooves into which the side-emitting type light-emitting device is inserted to change the optical path of the light emitted by the side-emitting type light-emitting device, thereby avoiding self-guided The light emitted by the light panel is partially concentrated. Therefore, the uneven brightness can be reduced.

In addition, the beads may be dispersed in the resin layer to irregularly reflect the light emitted by the side-emitting type light-emitting device, thereby preventing the light emitted from the light guide plate from being locally concentrated. Therefore, hot spots can be reduced.

In addition, since the printed circuit board and the light guide plate can be coupled to each other using optical path variation grooves formed in the light guide plate to reduce hot spots, no additional coupling portion or material such as an adhesive is required, and the backlight unit can be lowered. The thickness.

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 plate

110a, 110b‧‧‧ trench

115a, 115b‧‧‧ Optical path change trench

116‧‧‧ openings

220‧‧‧ beads

230‧‧‧ resin layer

300‧‧‧Printed circuit board

310a, 310b‧‧‧ side-emitting illumination device

320‧‧‧through hole

500‧‧‧ coupling

A, B‧‧‧ beam

K‧‧ specific area

1 is a cross-sectional view showing a backlight unit according to a first embodiment; FIG. 2 is a cross-sectional view showing a backlight unit according to a second embodiment; FIG. 3 is a diagram showing a third embodiment according to a third embodiment; FIG. 4 is a cross-sectional view showing a light propagation path of a backlight unit in a comparative example of the present invention; FIG. 5 is a view showing a light propagation path in a backlight unit according to an embodiment of the present invention; FIG. 6 is a partial cross-sectional view showing a backlight unit according to a fourth embodiment; FIG. 7 is a partial cross-sectional view showing a backlight unit according to a fifth embodiment; 6 is a partial cross-sectional view showing a backlight unit; and FIG. 9 is a partial cross-sectional view showing a backlight unit according to a seventh embodiment; Figure 10 is a partial cross-sectional view showing a backlight unit according to an eighth embodiment.

100. . . Light guide

110a, 110b. . . Trench

115a. . . Optical path change trench

300. . . A printed circuit board

310a, 310b. . . Side-emitting type light-emitting device

Claims (11)

A backlight unit for backlighting a display unit, comprising: a light guide plate, comprising a plurality of grooves; a plurality of side-emitting illumination devices are respectively disposed in the grooves; and an optical path change groove is disposed on Between the grooves, an optical path for changing the light emitted by the side-emitting illumination devices; and a resin layer disposed in the interior of the optical path variation groove, wherein the resin layer has a different refractive index The refractive index of the light guide plate. The backlight unit of claim 1, wherein the grooves are uniformly disposed along the light guide plate. The backlight unit of claim 1, wherein the grooves are formed on a bottom side of the light guide plate. The backlight unit of claim 1, wherein the optical path variation trench is formed between the trenches and formed on a top side of the light guide plate or a bottom side of the light guide plate. The backlight unit of claim 1, wherein the resin layer is disposed only in the interior of the optically variable trench. The backlight unit of claim 1, wherein a plurality of beads are dispersed in the resin layer. The backlight unit of claim 6, wherein the beads comprise at least one of acryl, ruthenium, glass, and polystyrene. The backlight unit of claim 1, further comprising a resin layer disposed on an inner wall of the trenches, wherein a refractive index of the resin layer is different from a refractive index of the light guide plate. The backlight unit of claim 1, wherein the optical path variation groove is formed on a bottom side of the light guide plate, and the side light-emitting type light-emitting device is disposed on a printed circuit board, wherein The through hole is formed at a position communicating with the optical path changing groove via the printed circuit board. The backlight unit of claim 9, wherein a coupling portion is inserted into the optical path changing groove formed in the bottom side of the light guide plate and the through hole to connect the light guide plate The printed circuit board is coupled. The backlight unit of claim 1, wherein the side-emitting type light-emitting device is provided in the form of a package in which a light-emitting diode (LED) is disposed.