KR20090073431A - Light source unit for back light panel - Google Patents

Abstract

A light source unit for a backlight panel is provided to totally reflect light emitted from a light emitting device by a long light emitting device receiver in a side of the light emitting element receiving unit, thereby reducing loss of light. A light guide member has a flat upper side(110), a lower side(120) facing the upper side, and a light emitting device receiver(130) protruded toward a lower side. A light emitting device(140) is mounted on the light emitting device receiver. The light emitting device receiver has a long shape to totally reflect light emitted from the light emitting device from a side of the light emitting device receiver to the inside. The light emitting device receiver gets wider in at least one direction according as the light emitting device receiver gets closer to the upper side.

Description

Light source unit for backlight panel {LIGHT SOURCE UNIT FOR BACK LIGHT PANEL}

The present invention relates to a light source unit for a backlight panel, and more particularly to a light source unit used for a backlight panel for backlighting a liquid crystal display.

Passive display devices, such as liquid crystal displays, can reflect or absorb ambient sunlight or room light to produce an image. Thus, ambient sunlight or room light is required to view the displayed image. However, there is a problem in that the displayed image cannot be viewed when the intensity of ambient sunlight or room light is not sufficient to illuminate the display panel. As an alternative to this problem, a backlight panel for backlighting the display panel is generally adopted.

The backlight panel includes a light source such as an incandescent lamp, a fluorescent lamp or a light emitting device (LED). The light emitted from the light source illuminates the LCD panel to realize the image. On the other hand, LED is often used as a backlight light source due to its excellent color reproducibility, and is expected to increase its use in the future as it is environmentally friendly.

1 is a cross-sectional view illustrating an edge type backlight panel for backlighting a liquid crystal display panel 37 (hereinafter, referred to as an LCD panel) according to the prior art.

Referring to FIG. 1, the light guide plate 27 is positioned under the LCD panel 37. The light guide plate converts light emitted from the light source 23w into surface light and emits the light upward. In addition, the reflective sheet 25 may be disposed under the light guide plate.

White light emitting devices (hereinafter, referred to as LEDs) are installed adjacent to the side surface of the light guide plate. The white LED emits white light toward the side of the light guide plate 27. The white LED may be mounted on the printed circuit board 21, and a plurality of LEDs may be mounted on one printed circuit board 21 to constitute an LED module.

Meanwhile, light blocking walls 29 are positioned above and below the white LED 23w. The light shielding wall prevents light emitted from the white LED 23w from being emitted to an area other than the side surface of the light guide plate 27. A reflective layer may be coated on an inner wall of the light blocking wall 27 to reflect light incident on the light blocking wall. The reflective layer may also be formed on an upper surface of the printed circuit board 21.

The diffusion plate 31 is positioned on the light guide plate 27. The diffusion plate 31 diffuses the light incident from the light guide plate 27 into a uniform light. In addition, a brightness enhancement film 33 and / or a dual brightness enhancement film 35 may be further interposed between the diffusion plate 31 and the LCD panel 37. The BEFs 33 and 35 condense the light emitted from the light guide plate 27 within a predetermined direction to increase luminance.

On the other hand, Figure 2 is a cross-sectional view for explaining a direct type backlight panel according to the prior art.

Referring to FIG. 2, the diffusion plate 61 is positioned below the LCD panel 67. The diffuser plate has an upper surface and a lower surface. A BEF 63 and / or a DBEF 65 may be interposed between the diffusion plate and the LCD panel 67. Meanwhile, the white LEDs 53w are spaced apart from the diffuser plate 61 and arranged below the bottom surface of the diffuser plate.

The white LEDs 53w emit white light toward the diffusion plate 61. The white LED may be mounted on the printed circuit board 51, and a plurality of LEDs may be mounted on one printed circuit board 51 to constitute an LED module. A plurality of LED modules may be disposed below the diffuser plate 61 for uniform backlighting.

On the other hand, the reflective sheet 55 is located under the exit surface of the white LEDs (53w). The reflective sheet 55 may have a reflective layer 55a thereon. The reflective sheet may be formed of an aluminum sheet, and a reflective layer 55a may be coated thereon. In addition, the reflective sheet 55 may be attached to the printed circuit board 51, as shown.

The reflective sheet 55 and the diffusion plate 61 are spaced apart from each other at a predetermined interval to form a gap 60a formed of an air layer. White light emitted from the white LED 53w is mixed with each other in the gap 60a and is incident on the diffusion plate 61.

3 is a cross-sectional view for explaining a white LED 23w or 53w according to the prior art.

Referring to FIG. 3, the white LED has a package body 71. The package body may be formed using an injection, pressing or processing technique, and in particular, may be injection molded using a plastic resin. The package body is formed to have a recess, and lead terminals 73 are exposed in the recess. In addition, the side wall of the groove may be formed of an inclined surface inclined at a predetermined angle.

The lead terminals 73 extend outside to protrude out of the package body 71. Lead terminals 73 protruding to the outside are connected to the printed circuit board and electrically connected to an external power source. The lead terminals 73 may be bent from outside to enable surface mounting.

Meanwhile, a heat sink 75 may be mounted below the package body 71, and a blue LED chip 77 emitting blue light may be mounted on the heat sink 75. The LED chip 77 is a GaN, InGaN, AlGaN or AlGaInN-based light emitting diode, and emits blue light in the range of 420 to 480 nm. The LED chip 77 has two electrodes to be connected to an external power source. The electrodes may be located on the same side or opposite sides of the LED chip 77. The electrodes may be electrically connected to the lead terminal through an adhesive, or as shown, may be connected to the lead terminal through a bonding wire.

The upper part of the blue LED chip 77 is mixed with a part of the light emitted from the LED chip 77 to be excited by the blue light to emit white light, the yellow phosphor to emit yellow light, or excited by the blue light to emit red light The red phosphor 81r that emits light and the green phosphor 81g that are excited by blue light and emit green light may be located. The phosphors may be coated on the LED chip 77 or may be contained and positioned in the molding member 79 as shown. The molding member 79 may be formed of an epoxy resin or a silicone resin, and may be formed of a single layer or multiple layers.

Meanwhile, the lens 83 may cover the LED chip 77 and the phosphors 81r and 81g, and the lens may have various shapes.

According to the prior art, white LEDs are adopted as a light source to provide a backlight panel. However, in the case of an edge type backlight panel, a specially designed package such as a side light emitting diode package must be used to disperse light incident on the light guide plate 27 at a wide direct angle. However, this side light emitting diode package also has a limit in increasing the directivity angle. On the other hand, in the case of the direct type backlight panel, spots are easily formed because the light emitted from the LED is not evenly distributed. To prevent this, the diffuser plate must be thickened or the distance between the diffuser plate and the LEDs must be increased. However, increasing the thickness of the diffuser plate or increasing the distance between the diffuser plate and the LEDs results in light loss. Moreover, a large number of LEDs must be regularly aligned to backlight a large LCD panel, and when using these multiple LEDs, it is difficult to achieve uniform backlighting at the boundary portions between the LEDs.

The problem to be solved by the present invention is to provide a light source unit that can reduce the loss of light and can emit a uniform light.

Another object of the present invention is to provide a light source unit for a backlight panel suitable for backlighting a large LCD.

In order to solve the above problems, the present invention provides a light source unit for a backlight panel. The light source unit according to the embodiments of the present invention includes a light emitting element light guide member. In addition, the light guide member has a flat upper surface, a lower surface facing the upper surface, and a light emitting element accommodation portion protruding from the lower surface. The light emitting element is mounted on the light emitting element accommodating part. Meanwhile, the light emitting element accommodating part has an elongated shape such that the light emitted from the light emitting element is totally internally reflected at the side thereof, and the closer to the upper surface, the wider the at least one axial direction. Accordingly, it is possible to reduce the loss of light emitted from the light emitting element, and to configure a backlight panel suitable for backlighting of a large LCD.

The light guide member may have a single light emitting element accommodating portion, but is not limited thereto and may have a plurality of light emitting element accommodating portions. In this case, the light emitting element accommodating parts may be arranged in a line, and the closer to the upper surface, the wider the light emitting device accommodating parts may be. In this case, the light emitting devices are mounted on the light emitting device receiving parts, respectively. Such a light source unit provides a light source unit suitable for an edge type backlight panel.

In some embodiments of the invention, the light guide member may have a square top surface. The light emitting element accommodating part may be positioned at the center of the lower surface of the light guide member, and may be wider in all directions as it is closer to the upper surface. By arranging such light source units, it is possible to backlight a large LCD panel.

On the other hand, the light guide member may include a diffusion material between the upper surface and the lower surface. Therefore, in the case of the direct type backlight panel, the light guide member may be used in place of the diffusion plate, and thus the diffusion plate of the prior art may be omitted.

According to embodiments of the present invention, it is possible to provide a light source unit capable of contributing to backlighting without losing light emitted from the light emitting device. In addition, since the backlight panel may be configured by arranging a plurality of light source units, it is possible to easily implement a large backlight panel that is difficult to implement using a conventional light guide plate. In addition, even if a failure occurs in one light source unit can be easily replaced with another light source unit to cope with the failure of the backlight panel during use.

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention; The following embodiments are provided as examples to sufficiently convey the spirit of the present invention to those skilled in the art. Accordingly, the invention is not limited to the embodiments described below and may be embodied in other forms. In the drawings, widths, lengths, thicknesses, and the like of components may be exaggerated for convenience. Like numbers refer to like elements throughout.

4 is a perspective view illustrating a light source unit 100 for a backlight panel according to an exemplary embodiment of the present invention, and FIG. 5 is a cross-sectional view of the light source unit of FIG. 4.

4 and 5, the light source unit 100 includes a light emitting element 140 and a light guide member. The light guide member includes an upper surface 110, a lower surface 120, and a light emitting element accommodating part 130. The upper surface 110 of the light guide member 110 forms a flat surface and defines a region where light is emitted. Meanwhile, the lower surface 120 is positioned to face the upper surface 110, and the light emitting device accommodating part 130 protrudes from the lower surface 120.

The light emitting element 140 is mounted at an end of the light emitting element accommodating part 130. The light emitting device is a white LED as described with reference to FIG. 3 and includes a blue LED chip and phosphors.

The light emitting element accommodating part 130 has an accommodating groove for accommodating the light emitting element 140, and a light emitting surface of the light emitting element 140 is disposed in the accommodating groove. In addition, the light emitting device accommodating part 130 has an elongated shape such that the light emitted from the light emitting device 140 is totally reflected from the side surface thereof, and has a shape that is wider as the upper surface 110 is closer to the upper surface 110. That is, the light emitting element accommodating part 130 of the side close to the accommodating groove in which the light emitting element 140 is accommodated has a generally elongated shape, and is widened as shown in the side of the upper side 110.

Such a shape causes total internal reflection to occur due to a difference in refractive index between the light emitting element accommodating part 130 and the surrounding air even when a reflective sheet or the like is not disposed near the end of the light emitting element accommodating part 130. To prevent it.

On the other hand, since the light emitting device accommodating part 130 is wider as the upper surface 110 gets closer, light may be widely spread in the light guide member. In particular, by dispersing a diffuser (not shown) between the lower surface 120 and the upper surface 110 of the light guide member, light can be widely dispersed in the light guide member. When the diffuser is distributed near the light emitting device 140, light scattered by the diffuser may be emitted to the outside, so that the diffuser is distributed near a portion where the light emitting device accommodating part 130 and the lower surface 120 meet each other. It is preferable.

On the other hand, the light emitting element receiving portion 130, as shown, is located in the center of the lower surface 120 of the light guide member, the closer to the upper surface may be wider in all directions. In this case, the upper surface 110 of the light guide member may be square. However, the number of light emitting device accommodating parts 130 is not particularly limited, and a plurality of light emitting device accommodating parts may be formed in one light guide member.

6 is a perspective view illustrating a light source unit for a backlight panel according to another exemplary embodiment of the present invention, and FIG. 7 is a sectional view of FIG. 6.

6 and 7, the light source unit includes light emitting elements 140a, 140b and 140c and a light guide member. In the present embodiment, the light guide member has an upper surface 110, a lower surface 120, and a plurality of light emitting element accommodating portions 130a, 130b, and 130c. The light emitting elements are mounted on the light emitting element accommodating portions, respectively.

Meanwhile, the plurality of light emitting element accommodating parts 130a, 130b, and 130c may be aligned in a line. To this end, the light guide member has an upper surface 110 and a lower surface 120 having an elongated shape along one axis direction.

As described with reference to FIGS. 4 and 5, the light emitting element accommodating parts 130a, 130b, and 130c have accommodating grooves for accommodating the light emitting elements, and light emitting surfaces of the light emitting elements are disposed in the accommodating grooves. . In addition, the light emitting element accommodating parts have an elongated shape such that the light emitted from the light emitting elements is totally reflected from the side surfaces thereof, and has a shape that is wider as the upper surface 110 is closer to the upper surface 110. That is, the light emitting element accommodating parts closer to the accommodating groove in which the light emitting elements are accommodated generally have an elongated shape having a cylindrical shape, and wider as shown in the side near the upper surface 110. However, in the present exemplary embodiment, the light emitting device accommodating parts 130a, 130b, and 130c may be wider as they are closer to the upper surface 110 in the direction in which they are arranged. That is, the light emitting element accommodating parts may be wider as they are closer to the upper surface 110 in the arranged direction than in the direction perpendicular to the arranged direction.

In addition, as described with reference to FIGS. 4 and 5, the diffusion material may be distributed in the light guide member. Therefore, the light emitted from the light emitting elements 140a, 140b, and 140c is emitted to the surface light source having an elongated shape through the upper surface 110 through the light guide member.

According to the present exemplary embodiment, an elongated surface light source may be realized by controlling the shapes of the light emitting element accommodating parts. Therefore, it is possible to provide a light source unit capable of emitting light to the light guide plate of the edge type backlight panel without using the side light emitting diode as in the prior art.

Also, in the present embodiment, the light guide member having the elongated top surface 110 and the bottom surface 120 has been described, but the edge type backlight is arranged by arranging the light guide members having the single light emitting element accommodating portions in a line. A light source unit capable of emitting light to the light guide plate of the panel can be formed.

8 is a perspective view illustrating a state in which light source units are arranged.

Referring to FIG. 8, the light source units 100a, 100b, 100c and 100d are arranged next to each other. Each of the light source units is the same as the light source unit 100 described with reference to FIGS. 4 and 5.

By arranging the light source units, it is possible to construct a direct backlight panel for backlighting a large LCD panel. At this time, the number of light source units is determined according to the size of the light source units and the size of the LCD panel.

According to the prior art, although the surface light source is realized by arranging the LEDs for the backlight panel, it is difficult to arrange the LEDs in close contact, and it is difficult to control the directing angle of the light so that the light emitted from the LEDs is emitted within a certain area. Because of this, it is difficult to achieve uniform light in the boundary regions between the LEDs.

However, according to the present embodiment, the light source units emitting uniform light can be arranged in close contact with each other, thereby realizing a backlight panel capable of emitting uniform light over a large area of a large LCD panel.

In particular, since the light guide members may play a role of the diffusion plate by distributing the diffusion material in the light guide member, the diffusion plate used in the conventional direct type backlight panel may be omitted.

1 is a cross-sectional view illustrating an edge type backlight panel according to the prior art.

2 is a cross-sectional view illustrating a direct backlight panel according to the related art.

3 is a cross-sectional view illustrating a white light emitting device according to the prior art.

4 is a perspective view illustrating a light source unit for a backlight panel according to an embodiment of the present invention.

5 is a cross-sectional view of the light source unit of FIG. 4.

6 is a perspective view illustrating a light source unit for a backlight panel according to another embodiment of the present invention.

7 is a cross-sectional view of the light source unit of FIG. 6.

8 is a perspective view illustrating a state in which the light source units of FIG. 4 are arranged.

Claims (4)

In the light source unit for a backlight panel, Light emitting element; And A light guide member having a flat upper surface, a lower surface facing the upper surface, and a light emitting element receiving portion protruding from the lower surface; The light emitting element is mounted on the light emitting element receiving portion, The light emitting element accommodating part has a long shape such that the light emitted from the light emitting element is totally internally reflected at a side thereof, and the light source unit is wider in at least one axis direction as it is closer to the upper surface. The method according to claim 1, The light guide member has a plurality of light emitting element accommodation portions, The light emitting element accommodating portions are arranged in a line, and the closer to the upper surface, the wider the light emitting element accommodating portion is. A light source unit in which light emitting elements are mounted on the light emitting element receiving portions, respectively. The method according to claim 1, The light guide member has a square upper surface, The light emitting element accommodating part is positioned at the center of the lower surface of the light guide member, and the closer to the upper surface, the light source unit widens in all directions. The method according to claim 1, The light guide member includes a light diffusion unit between the upper surface and the lower surface.

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