KR20070068116A - Backlight assembly and liquid crystal display having the same - Google Patents

Abstract

A backlight assembly and an LCD(Liquid Crystal Display) including the same are provided to align positions of the light emitting portion of a light emitting diode and of the light incoming surface of a light guide panel, thereby improving the light efficiency. A light source unit includes at least one light emitting diode(430). The light source unit is mounted to an FPCB(Flexible Printed Circuit Board)(450). A light guide panel(500) converts the light transmitted from the light source unit into the surface light. A mold frame(800) has a predetermined space for receiving the light source unit and the light guide panel. A bottom cover(900) is arranged at the lower portion of the mold frame in order to support the mold frame and combined with the mold frame. The FPCB is arranged between the lower surface of the light guide panel and bottom cover and fixed on the bottom cover.

Description

Backlight assembly and liquid crystal display including the same {Backlight assembly and liquid crystal display having the same}

1 is an exploded perspective view of a liquid crystal display having a backlight assembly using a lamp as a light source according to an example of the prior art;

2 is a schematic cross-sectional view of a liquid crystal display having a backlight assembly using a light emitting diode as a light source according to another example of the prior art.

3 is a graph showing the relationship between the light efficiency according to the thickness of the light emitting diode and the light guide plate.

4A is a schematic cross-sectional view of a liquid crystal display device having a backlight assembly according to a first embodiment of the present invention, and FIG. 4B is a schematic perspective view of the light emitting diode shown in FIG. 4A.

5 is a schematic cross-sectional view of a liquid crystal display device having a backlight assembly according to a second embodiment of the present invention.

6 is a schematic cross-sectional view of a liquid crystal display device having a backlight assembly according to a third embodiment of the present invention.

7A to 7C are schematic plan views, side views, and perspective views of the light emitting diode shown in FIG. 6.

8 is a schematic exploded perspective view of a liquid crystal display including a backlight assembly using a light emitting diode as a light source according to the present invention.

* Description of the symbols for the main parts of the drawings *

50; Front case 100; LCD panel

220, 240; A driving circuit unit 300; Top chassis

430, 440; Light emitting diode 500; Light guide plate

600; Reflector 800; Mold frame

900; Bottom cover

The present invention relates to a backlight assembly and a liquid crystal display including the same, and more particularly, to a backlight assembly and a liquid crystal display for improving light efficiency by aligning positions of a light emitting diode and a light guide plate.

In general, the liquid crystal display (LCD) is expanding its application range due to features such as lightweight, thin, low-power drive, full-color, high-resolution implementation. Currently, liquid crystal displays are used in computers, notebooks, PDAs, telephones, TVs, and audio / video devices. Such a liquid crystal display device adjusts the amount of light transmitted according to an image signal applied to a plurality of control switches arranged in a matrix to display a desired image on a panel of the liquid crystal display device.

1 is an exploded perspective view of a liquid crystal display including a backlight assembly using a lamp as a light source according to an example of the prior art.

The liquid crystal display illustrated in FIG. 1 includes an edge type backlight assembly mainly used for small and medium-sized liquid crystal displays such as a laptop computer and a desktop computer. The liquid crystal display includes a top chassis 300 and an LCD panel ( 100, a driving circuit unit 220 and 240, a plurality of optical sheets 700, a lamp unit 400, a light guide plate 500, a reflecting plate 600, a mold frame 800, and a bottom cover 900. In the liquid crystal display as described above, the lamp unit 400 is installed at the edge of the LCD panel 100 so that light generated from the lamp unit is irradiated to the LCD panel through the transparent light guide plate 500 positioned below the LCD panel. That's the way.

2 is a schematic cross-sectional view of a liquid crystal display having a backlight assembly using a light emitting diode as a light source according to another example of the prior art. Referring to FIG. 2, a top chassis 300, an LCD panel (not shown), a driving circuit unit (not shown), a plurality of optical sheets (not shown), a light emitting diode 430, a light guide plate 500, a mold frame ( 800 and bottom cover 900. In the liquid crystal display illustrated in FIG. 2, a light emitting diode 430 is used as a light source, and the light emitting diode 430 uses a side view type light emitting diode in which light is emitted in a lateral direction.

The light emitting diode 430 is mounted on the flexible printed circuit board 450, and a light emitting part, which is a part of light emitted from the light emitting diode 430, is emitted from one side of the light guide plate 500, that is, the light emitting diode. The light is disposed so as to correspond to the incident surface (incident surface). Meanwhile, in order to arrange the light emitting diode 430 on the light incident surface of the light guide plate 500, the flexible printed circuit board 450 on which the light emitting diode 430 is mounted may be formed using the double-sided tape 420. It is attached and fixed on the lower surface of the 500 and the lower surface of the mold frame. However, due to the thickness of the double-sided tape 420, the light exit portion of the light emitting diode 430 and the light incident surface of the light guide plate 500 are disposed not to match each other. As a result, a part of the light emitted from the light emitting diode 430 does not enter the light incident surface of the light guide plate 500, resulting in a problem that the light efficiency is lowered.

SUMMARY OF THE INVENTION The present invention has been made to overcome the above-mentioned problems, and an object of the present invention is to provide a backlight assembly and a liquid crystal display device for improving light efficiency by aligning positions of a light emitting diode and a light guide plate.

According to an aspect of the present invention for achieving the above object, a light source unit having at least one light emitting diode; A flexible printed circuit board for mounting the light source unit; A light guide plate for converting light incident from the light source unit into a surface light source; In order to support the light source unit and the light guide plate, a mold frame having a predetermined space therein and a bottom cover disposed below the mold frame and supported by the mold frame to support the mold frame. A chain circuit board is disposed between the bottom surface of the light guide plate and the bottom cover, and the flexible printed circuit board is fixed on the bottom cover.

The method may further include an adhesive member having a predetermined thickness disposed between the flexible printed circuit board and the bottom cover.

The adhesive member is characterized in that the double-sided tape.

The light emitting diode is a light emitting diode chip; And a lead terminal for applying power to the light emitting diode chip and a reflecting member for reflecting light emitted from the light emitting diode chip to the light incident portion side of the light guide plate, wherein the lead terminal is connected to the center of the light emitting portion of the light emitting diode. The light guide plate is formed to have a predetermined height so as to coincide with the center of the light incident surface.

The lead terminal of the light emitting diode is characterized in that soldered on the flexible printed circuit board.

On the other hand, according to another aspect of the invention, the light source unit having at least one light emitting diode; A flexible printed circuit board for mounting the light source unit; A light guide plate for converting light incident from the light source unit into a surface light source; In order to support the light source unit and the light guide plate, a mold frame having a predetermined space therein and a bottom cover disposed below the mold frame and supported by the mold frame to support the mold frame. One end of the printed circuit board is formed in parallel with the light exit surface of the light guide plate, the other end is bent in parallel with the light incident surface of the light guide plate, and the flexible printed circuit board is formed at the center of the light exit part of the light emitting diode and the mouth of the light guide plate. It is characterized in that the center of the optical surface is arranged to match.

The light emitting diode is mounted on the other end of the flexible printed circuit board.

One end of the flexible printed circuit board is disposed between the mold frame and the bottom cover, and the other end of the flexible printed circuit board is disposed on the side wall of the mold frame parallel to the light incident surface of the light guide plate. do.

And a first adhesive member having a predetermined thickness disposed between one end of the flexible printed circuit board and the bottom cover, and a second adhesive member disposed between the other end of the flexible printed circuit board and the sidewall of the mold frame. do.

The first adhesive member and the second adhesive member may be double-sided tapes.

The light emitting diode is a light emitting diode chip; A lead terminal for applying power to the light emitting diode chip and a reflecting member for reflecting the light emitted from the light emitting diode chip to the light incident part side of the light guide plate, the lead terminal being the other end of the flexible printed circuit board. Characterized in that formed to be mounted on.

The lead terminal is characterized in that formed in a direction parallel to the direction of the outgoing light.

According to another aspect of the present invention, there is provided a liquid crystal display device comprising a backlight assembly having the above characteristics and an LCD panel disposed on the backlight assembly to display an image.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

3 is a graph showing the relationship between the light efficiency according to the thickness of the light emitting diode and the light guide plate. Referring to FIG. 3, when the thickness of the light guide plate and the thickness of the light emitting diode are the same or the thickness of the light emitting diode is slightly larger, it can be seen that the light efficiency is good. In addition, the smaller the distance between the light emitting portion of the light emitting diode and the light receiving portion of the light guide plate, the better the light efficiency. For the above reason, the thickness of the light emitting diode, in detail, the thickness of the light emitting portion of the light emitting diode and the thickness of the light guide plate are formed to be substantially the same.

Therefore, the light efficiency of the light emitting diode must be coincident with the center of the light incident surface of the light guide plate. Hereinafter, the backlight assembly in which the center of the light emitting part of the light emitting diode and the light incident surface center of the light guide plate are aligned will be described in detail.

4A is a schematic cross-sectional view of a liquid crystal display device having a backlight assembly according to a first embodiment of the present invention, and FIG. 4B is a schematic perspective view of the light emitting diode shown in FIG. 4A.

Referring to FIG. 4A, the liquid crystal display includes a light emitting diode used as a light source, a flexible printed circuit board 450 for mounting the light emitting diode, and a light guide plate 500 for converting light incident from the light emitting diode into a surface light source. ), In order to support the light emitting diode 430, the flexible printed circuit board 450, and the light guide plate, the mold frame 800 having a predetermined space therein and the mold frame 800 to support the mold frame 800. It is disposed at the bottom, and includes a bottom cover 900 and the top chassis 300 to be fastened.

The light emitting diode 430 is mounted on the flexible printed circuit board 450, and a portion (hereinafter, referred to as a light emitting portion) from which light is emitted from the light emitting diode 430 is one side of the light guide plate 500. The light emitted from the light emitting diode is disposed to correspond to the incident surface (hereinafter referred to as a light incident surface). Preferably, the center of the light exit portion of the light emitting diode 430 and the center of the light incident surface of the light guide plate 500 are disposed to coincide with each other.

In order to arrange the light emitting diode as described above, the flexible printed circuit board 450 on which the light emitting diode 430 is mounted is fixed on the bottom cover 900 using the adhesive member 420. An adhesive member having a predetermined thickness is disposed between the flexible printed circuit board 450 and the bottom cover 900 to fix the flexible printed circuit board 450 on the bottom cover 900. At this time, it is preferable that the adhesive member 420 uses a double-sided tape.

When the adhesive member 420 is disposed between the flexible printed circuit board 450 and the bottom cover 900 as described above, since the thickness of the adhesive member 420 is not affected, the upper portion of the flexible printed circuit board In other words, the surface on which the light emitting diode is mounted is in close contact with the bottom surface of the light guide plate 900 and the bottom surface of the mold frame 800, so that the center of the light exit portion of the light emitting diode 430 and the mouth of the light guide plate 500 are formed. The optical surface centers may be identically aligned.

Referring to FIG. 4B, the light emitting diode 430 is a side view light emitting diode used as a light source of a liquid crystal display. The light emitting diode includes a substrate 431, a first lead terminal 432, a second lead terminal 433, a light emitting diode chip 434, a reflective member 435, a wire 436, and a molding part 437. do.

Looking at the LED of the side view type, a first lead terminal 432 and a second lead terminal 433 formed on the substrate 432 are disposed, and the LED chip 434 is disposed on the second terminal. It is mounted. A reflective member 435 is formed on the substrate to reflect light emitted from the light emitting diode chip 434 laterally, and the molding part 437 encapsulates the light emitting diode chip 434. Portions mounted on the flexible printed circuit board 450 are the first lead terminal 432 and the second lead terminal 433, and are connected to the light emitting diode chip through the first lead terminal and the second lead terminal. Power is applied and light is emitted from the light emitting diode chip.

5 is a schematic cross-sectional view of a liquid crystal display device having a backlight assembly according to a second embodiment of the present invention. The liquid crystal display according to the second exemplary embodiment of FIG. 5 differs from the liquid crystal display according to the first exemplary embodiment in that a light emitting diode is mounted at a predetermined interval apart from the flexible printed circuit board. Is almost similar.

Referring to FIG. 5, the flexible printed circuit board 450 on which the light emitting diode 430 is mounted is fixed to the bottom cover 900 by using an adhesive member 420 such as a double-sided tape. . An adhesive member having a predetermined thickness is disposed between the flexible printed circuit board 450 and the bottom cover 900 to fix the flexible printed circuit board 450 on the bottom cover 900. When the adhesive member 420 is disposed between the flexible printed circuit board 450 and the bottom cover 900 as described above, since the thickness of the adhesive member 420 is not affected, the upper portion of the flexible printed circuit board In other words, the surface on which the light emitting diode is mounted is in close contact with the bottom surface of the light guide plate 900 and the bottom surface of the mold frame 800, so that the center of the light exit portion of the light emitting diode 430 and the mouth of the light guide plate 500 are formed. The optical surface centers may be identically aligned.

In addition, the first and second lead terminals 432 and 433 of the light emitting diode are formed high so as to match the center of the light emitting part of the light emitting diode 430 with the light receiving surface center of the light guide plate 500. It is mounted on the printed circuit board 450. Alternatively, when the light emitting diode 430 is mounted on the flexible printed circuit board 450 through soldering, the soldering may be thickened to form a high position at which the light emitting diode 430 is mounted.

6 is a schematic cross-sectional view of a liquid crystal display device having a backlight assembly according to a third embodiment of the present invention.

Referring to FIG. 6, the liquid crystal display includes a light emitting diode 430 used as a light source, a flexible printed circuit board 450 for mounting the light emitting diode, and a light incident from the light emitting diode to a surface light source. In order to support the light guide plate 500, the light emitting diode 430, the flexible printed circuit board 450 and the light guide plate, a mold frame 800 having a predetermined space therein and the mold frame 800 are supported. Is disposed below the mold frame, and includes a bottom cover 900 and the top chassis 300 to be fastened.

The light emitting diode 440 is mounted on the flexible printed circuit board 450, and the light emitting part of the light emitting diode 440 is disposed to correspond to the light incident surface of the light guide plate 500. Preferably, the center of the light exit portion of the light emitting diode 440 and the center of the light incident surface of the light guide plate 500 are disposed to coincide with each other.

In order to arrange the light emitting diode as described above, one end of the flexible printed circuit board 450 is formed in parallel with the light exit surface of the light guide plate, and the other end is bent in parallel with the light incident surface of the light guide plate. The printed circuit board 450 is bent in an L shape. One end of the flexible printed circuit board 450 is disposed between the mold frame and the bottom cover, and the other end of the flexible printed circuit board 450 is disposed on a sidewall of the mold frame parallel to the light incident surface of the light guide plate. It is fixed.

In this case, in order to fix one end and the other end of the flexible printed circuit board, the first adhesive member 421 is disposed between the one end and the bottom cover of the flexible printed circuit board, and the second adhesive member 422 is The flexible printed circuit board is disposed between the other end of the flexible printed circuit board and the sidewall of the mold frame to fix the flexible printed circuit board. Here, the light emitting diode 450 is mounted on the other end of the flexible printed circuit board. In addition, it is preferable to use a double-sided tape for the first adhesive member and the second adhesive member.

7A to 7C are schematic plan views, side views, and perspective views of the light emitting diode 440 shown in FIG. 6.

7A to 7C, the light emitting diode 440 may include a substrate 441, a first lead terminal 442, a second lead terminal 443, a light emitting diode chip 444, and a reflective member 445. , The wire 446 and the molding part 447.

Since the light emitting diode 440 is almost similar in configuration to the light emitting diode 430 shown in FIG. 4B, only the different parts will be described below. Portions mounted on the flexible printed circuit board 440 may be a first lead terminal 442 and a second lead terminal 443 of the light emitting diode 440, and may be formed through the first lead terminal and the second lead terminal. Power is applied to the LED chip, and light is emitted from the LED chip.

In this case, the first lead terminal 442 and the second lead terminal 443 are formed in parallel directions of light emitted from the light emitting diode. That is, the first lead terminal 442 and the second lead terminal 443 extend to the rear side of the reflective member.

8 is a schematic exploded perspective view of a liquid crystal display including a backlight assembly using a light emitting diode as a light source according to the present invention.

Referring to FIG. 8, a liquid crystal display using a light emitting diode as a light source includes a front case 50, a top chassis 300, a liquid crystal panel 100, driving circuits 220 and 240, and a plurality of optical sheets 700. , A light emitting diode 430, a flexible printed circuit board 450, a light guide plate 500, a reflective plate 600, a mold frame 800, and a bottom cover 900.

The driving circuits 220 and 240 are connected to the LCD panel 100, and include a gate side printed circuit board 224 for mounting a control IC and applying a predetermined gate signal to a gate line of the TFT substrate 120. And a data side printed circuit board 244 for mounting a control IC (integrated circuit) and applying a predetermined data signal to a data line of the TFT substrate 120, and a TFT substrate 120 and a gate having an exposed ground pattern. The gate side flexible printed circuit board 222 for connecting between the side printed circuit boards 224 and the data side for connecting between the TFT substrate 120 and the data side printed circuit board 244 with an exposed ground pattern. Flexible printed circuit board 242.

The gate side and data side printed circuit boards 224 and 244 are connected to the gate side and data side flexible printed circuit boards 222 and 242 to apply a gate driving signal and an external image signal. In this case, the gate side and data side printed circuit boards 224 and 244 may be integrated to form a single printed circuit board.

In addition, the flexible printed circuit boards 222 and 242 are equipped with a driving IC (not shown), and the LCD (Read, Green, Blue) signals generated from the printed circuit boards 224 and 244, digital power supplies, etc. To 100. In the exemplary embodiment of the present invention, a tape-automated bonding (TAB) mounting method is described as an example. Alternatively, a COG installed in a thin film transistor substrate is not mounted on the flexible printed circuit boards 222 and 242. (Chip On Glass) It can also be applied to the mounting method.

The top chassis 300 is formed in a rectangular frame having a flat portion and a sidewall portion that are bent at right angles to prevent the LCD panel 100 and the driving circuit parts 220 and 240 from being separated from each other and to protect them from impacts applied from the outside. do.

The light emitting diode 430 is mounted on the flexible printed circuit board 450 and disposed on the light incident surface side of the light guide plate 500.

The light guide plate 500 changes the light incident from the light emitting diode 430 into light having an optical distribution in the form of a surface light source. As the light guide plate 500, a wedge type plate or a parallel flat plate may be used.

A plate having a high light reflectance is used as the reflective plate 600, and the optical sheet 700 is disposed on the light guide plate 500 to uniform the luminance distribution of the light emitted from the light guide plate 500.

The mold frame 800 has an accommodating space formed in the mold frame, and the accommodating space includes the light emitting diode 430, the light guide plate 500, and a reflector plate 600 disposed below the light guide plate 500. A plurality of optical sheets 700 installed on the light guide plate 500 are inserted.

The mold frame 800 is supported by the bottom cover 900. The bottom cover 900 is preferably formed of a metal material in order to prevent the mold frame 800 from bending, and the bottom cover 800 may be mounted at a position opposite to the light emitting diode 430 as necessary. It may be used for both.

What has been described above is only an exemplary embodiment of the backlight assembly and the liquid crystal display device including the same according to the present invention, and the present invention is not limited to the above-described embodiment, as claimed in the following claims, Without departing from the gist of the invention, anyone of ordinary skill in the art to which the present invention will have the technical spirit of the present invention to the extent that various modifications can be made.

As described above, according to the present invention, by changing the position of the adhesive member for fixing the flexible printed circuit board on which the light emitting diode is mounted, or by modifying the shape of the flexible printed circuit board and the light emitting diode, the light emitting portion and the light guide plate of the light emitting diode By aligning the center of the light receiving surface of the, it is possible to increase the light efficiency of the backlight assembly.

Claims (13)

A light source unit having at least one light emitting diode; A flexible printed circuit board for mounting the light source unit; A light guide plate for converting light incident from the light source unit into a surface light source; In order to accommodate the light source unit and the light guide plate, a mold frame having a predetermined space therein and In order to support the mold frame, the bottom cover is disposed below the mold frame, and coupled to the mold frame, The flexible printed circuit board is disposed between the bottom surface of the light guide plate and the bottom cover, wherein the flexible printed circuit board is fixed on the bottom cover. The method of claim 1, And a bonding member having a predetermined thickness disposed between the flexible printed circuit board and the bottom cover. The method of claim 2, And said adhesive member is a double sided tape. The method of claim 2, The light emitting diode, Light emitting diode chips; A lead terminal for applying power to the light emitting diode chip; And a reflecting member for reflecting the light emitted from the light emitting diode chip to the light incident portion side of the light guide plate, wherein the lead terminal has a predetermined height such that the center of the light exit portion of the light emitting diode coincides with the light incident surface center of the light guide plate. The backlight assembly, characterized in that formed. The method of claim 4, wherein And a lead terminal of the light emitting diode is soldered onto the flexible printed circuit board. A light source unit having at least one light emitting diode; A flexible printed circuit board for mounting the light source unit; A light guide plate for converting light incident from the light source unit into a surface light source; In order to accommodate the light source unit and the light guide plate, a mold frame having a predetermined space therein and In order to support the mold frame, the bottom cover is disposed below the mold frame, and coupled to the mold frame, One end of the flexible printed circuit board is formed in parallel with the light exit surface of the light guide plate, the other end is bent in parallel with the light incident surface of the light guide plate, and the flexible printed circuit board has a center of the light exit portion of the light emitting diode and the light guide plate. The backlight assembly according to claim 1, characterized in that the center of the light incident surface is arranged to match. The method of claim 6, And the light emitting diode is mounted on the other end of the flexible printed circuit board. The method of claim 7, wherein One end of the flexible printed circuit board is disposed between the mold frame and the bottom cover, and the other end of the flexible printed circuit board is disposed on the side wall of the mold frame parallel to the light incident surface of the light guide plate. Backlight assembly. The method of claim 8, And a first adhesive member having a predetermined thickness disposed between one end of the flexible printed circuit board and the bottom cover, and a second adhesive member disposed between the other end of the flexible printed circuit board and the sidewall of the mold frame. Backlight assembly. The method of claim 9, And the first adhesive member and the second adhesive member are double sided tapes. The method of claim 7, wherein The light emitting diode, Light emitting diode chips; A lead terminal for applying power to the light emitting diode chip; And a reflecting member for reflecting the light emitted from the light emitting diode chip to the light incident portion side of the light guide plate, wherein the lead terminal is formed to be mounted on the other end of the flexible printed circuit board. The method of claim 11, The lead terminal is a backlight assembly, characterized in that formed in a direction parallel to the direction of the outgoing light. The backlight assembly according to any one of claims 1 to 12 and And an LCD panel disposed on the backlight assembly and configured to display an image.

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