KR20110039650A - Backlight unit - Google Patents

Abstract

PURPOSE: A backlight unit is provided to stick an LED, which is used as a light source, to a light guide plate to prevent the leakage of light and the degradation of luminance. CONSTITUTION: A backlight unit(100) comprises: a light guide plate(120) which includes plural protrusions protruding toward a display panel; and a printed circuit board which includes not only plural LEDs(Light Guide Devices) generating light but also plural grooves for the insertion of the plural protrusions.

Description

Backlight Unit {BACKLIGHT UNIT}

The present invention relates to a backlight unit used as an external light source of a flat panel display device, and more particularly, to a backlight unit capable of preventing luminance degradation and light leakage by assembling the light source and the light guide plate in close contact.

In recent years, as the information age has entered, the display field for visually expressing electrical information signals has been rapidly developed, and various flat panel display devices having excellent performance of thinning, light weight, and low power consumption have been developed. Flat Display Device has been developed and is rapidly replacing the existing Cathode Ray Tube (CRT).

Specific examples of such a flat panel display device include a liquid crystal display device (LCD), a plasma display panel device (PDP), a field emission display device (FED), and an electroluminescent display device. (Electro luminescence Display Device: ELD) and the like, these are commonly used as an essential component of a flat panel display panel that implements an image, a flat panel display panel has a pair of light emitting or polarizing material layer in between It has a configuration in which a transparent insulating substrate is faced and bonded together.

The dual liquid crystal display displays an image by adjusting the light transmittance of the liquid crystal using an electric field. To this end, the liquid crystal display device includes a display panel having a liquid crystal cell, a backlight unit for irradiating light to the display panel, and a driving circuit for driving the liquid crystal cell.

The display panel is formed such that a plurality of unit pixel regions are defined by crossing a plurality of gate lines and a plurality of data lines. In this case, each pixel area includes a thin film transistor array substrate and a color filter array substrate facing each other, a spacer positioned to maintain a constant cell gap between the two substrates, and a liquid crystal filled in the cell gap.

The thin film transistor array substrate includes a gate line and a data line, a thin film transistor formed of a switch element at each intersection of the gate lines and the data lines, a pixel electrode formed of a liquid crystal cell and connected to the thin film transistor, and the like. It consists of the applied alignment film. The gate lines and the data lines receive signals from the driving circuits through the respective pad parts. The thin film transistor supplies the pixel voltage signal supplied to the data line to the pixel electrode in response to the scan signal supplied to the gate line.

The color filter array substrate includes color filters formed in units of liquid crystal cells, a black matrix for distinguishing between color filters and reflecting external light, a common electrode for supplying a reference voltage to the liquid crystal cells in common, and an alignment layer applied thereon. It consists of.

The display panel is completed by aligning the separately manufactured thin film transistor substrate and the color filter array substrate, and then bonding them to each other, injecting and encapsulating a liquid crystal.

On the other hand, as mentioned above, the liquid crystal display device includes a backlight unit which is a separate external light source for irradiating light to the non-light emitting display panel. In particular, in the case of a transmissive liquid crystal display device, a separate dimming device that emits light and guides the back surface of the display panel, that is, a backlight unit is necessary.

Hereinafter, a backlight unit according to the related art will be described with reference to the accompanying drawings.

1 is an exploded perspective view of a backlight unit according to the prior art, Figure 2 is a plan view of an optical sheet included in the backlight unit shown in FIG.

As shown in FIG. 1, the backlight unit according to the related art is mounted on the rear surface of the support main 10 to transmit light to a display panel (not shown), and the rear surface of the support main 10. Light Emitting Diode Flexible Printed Circuit (LED FPC) including an LED mounted on the light guide plate 20 to emit light at one end of the light guide plate 20 (hereinafter referred to as LED FPC, 30), the light guide plate 20 It includes at least one optical sheet 40 which scatters or diffuses the light emitted from the light, and transmits the light to the display panel (not shown) and includes at least one ear 41 at each side.

According to the prior art, after the light guide plate 20 is seated on the support main 10, the LED FPC 30 is inserted into the support structure of the support main 10 and coupled thereto, and the optical sheet 40 has ears at both sides ( 41 is seated on the upper surface of the light guide plate 20 in a state where it is positioned to be inserted into the escape groove of the support main 10.

On the other hand, in order for the LED to be properly applied as a light source of the backlight unit, it is important to closely close the LED (not shown) and the light guide plate 20 that are configured inside the LED FPC 30 to prevent light leakage phenomenon. Distance between the sheet) and the light guide plate 20 needs to be maintained at 0.05 mm or less. By the way, according to the prior art, the light guide plate 20 is seated on the support main 10, the LED FPC 30 is inserted into the mounting structure of the support main 10, the light guide plate 20, LED FPC 30 And the support main 10 is assembled. Accordingly, even after the light guide plate 20, the LED FPC 30 and the support main 10 are assembled, even if the interval between the LED (not shown) and the light guide plate 20 of the LED FPC 30 is 0.05 mm or more, Since it is not possible to recognize the fact, light leakage occurs in the backlight unit, resulting in a decrease in luminance.

In addition, as shown in FIG. 2, according to the related art, before the optical sheet 40 is seated on the upper surface of the light guide plate 20, the ear parts 41 on both sides of the optical sheet 40 are inserted into the escape groove of the support main 10. It is inserted to fit, which is to fit the top and bottom of the optical sheet 40. By the way, the outermost size of the optical sheet 40 is increased by the plurality of ear parts 41 protruding on both sides of the optical sheet 40, and there is a problem in that there is a limit in unit cost reduction, and the ear parts 41 are provided. There is a problem in that the light leakage phenomenon through the luminance decrease occurs.

Accordingly, the present invention is to provide a backlight unit that can be directly bonded to the LED flexible printed circuit board and the light guide plate, the LED and the light guide plate used as a light source, to prevent light leakage phenomenon and brightness degradation. The purpose is.

In order to solve the above problems, the present invention is a light guide plate including a plurality of projections protruding toward the display panel on one side and a plurality of LEDs for generating the light is mounted, a plurality of projections on one side so that each of the plurality of projections is inserted Provided is a backlight unit comprising an LED flexible printed circuit board having an escape groove.

As described above, according to the present invention, the flexible printed circuit film for driving the LED used as the light source and the light guide plate are directly coupled by the guide grooves and projections formed in each, thereby providing a gap between the LED used as the light source and the light guide plate. Since it can be kept below 0.05 mm, it is possible to minimize the light leakage phenomenon generated in the gap between the LED and the light guide plate. In addition, the optical sheet seated on the upper surface of the light guide plate is distinguished from the top and bottom by using the uneven parts formed to be inserted into the escape grooves of the flexible printed circuit film instead of the ear parts formed by protruding from both sides thereof. The unit cost can be reduced by preventing the increase, and light leakage through the ear can be prevented, thereby preventing the decrease in luminance.

Hereinafter, a backlight unit according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is an exploded perspective view of a backlight unit according to an embodiment of the present invention. 4 is a plan view of a light guide plate included in the backlight unit illustrated in FIG. 3, and FIG. 5 is a plan view of an LED flexible printed circuit board included in the backlight unit illustrated in FIG. 3, and FIG. 6 is shown in FIG. 3. A plan view of the optical sheet included in the backlight unit.

As shown in FIG. 3, the backlight unit 100 according to an exemplary embodiment of the present invention includes a support main 110 and a support main 110 formed in a rectangular frame shape to accommodate each component of the backlight unit 100. A plurality of LEDs (Light Emitting) to generate light on the light guide plate 120 for mounting the light to the back of the display panel (not shown), one side of the support main 110 (shown below in Figure 3) Diode Flexible Printed Circuit (LED FPC), which is disposed so as to be in close contact with one side of the light guide plate 120 (LED FPC, hereinafter referred to as 'LED FPC', 130), located on the light guide plate 120 At least one optical sheet 140 for scattering or diffusing the light emitted from the 120 to be transmitted to the display panel (not shown).

Here, the light guide plate 120, as shown in FIG. 4, is formed to include a plurality of protrusions 121 to be coupled with the LED FPC 130. The plurality of protrusions 121 may be spaced apart from one side (shown below in FIG. 4) of the light guide plate at predetermined intervals and protrude toward the display panel (not shown). At this time, the height of the protrusion 121 is greater than or equal to the overall thickness of at least one optical sheet 140 seated on the upper surface of the light guide plate 120, each of the plurality of protrusions 121 is adjacent to one end of the light guide plate 120, In the LED FPC 130, the LED FPC 130 is disposed at a position that does not invade the light emitting region of the LED (not shown) that generates light.

As illustrated in FIG. 5, the LED FPC 130 is formed to include a plurality of escape grooves 131 to be coupled to the light guide plate 120. The plurality of escape grooves 131 are formed to insert and couple the plurality of protrusions 121 of the light guide plate 120. The width of the escape groove 131 is determined to be greater than or equal to the width of the protrusion 121 so that the escape groove 131 into which the protrusion 121 is inserted can maintain the shape of the groove. As such, the plurality of protrusions 121 are inserted into and coupled to the plurality of escape grooves 131, respectively, such that the LED FPC 130 overlaps at least some of the ends of the light guide plate 120 on which the plurality of protrusions 121 are formed. To be combined.

At least one optical sheet 140, as shown in Figure 6, is formed to include a plurality of uneven portion 141 for distinguishing the upper and lower. Concave-convex portion 141 is formed so that a portion of the optical sheet 140 is extended so as to fit in the escape groove 131, the projection 121 is inserted. When the plurality of uneven parts 141 are inserted into the plurality of guide grooves 131, respectively, the plurality of uneven parts 141 may be seated on the upper surface of the light guide plate 120 while the optical sheet 141 is aligned.

7 is a view showing an assembly process of the backlight unit according to an embodiment of the present invention, Figure 8 is a cross-sectional view between 'I-II' in Figure 7a.

In order to assemble the backlight unit according to an embodiment of the present invention, first, as shown in FIG. 7A, the plurality of protrusions 121 formed on the light guide plate 120 are formed on the LED FPC 130. Inserted in accordance with the), the light guide plate 120 and the LED FPC (130) are combined in a form that at least partially overlap each other. As such, since the light guide plate 120 and the LED FPC 130 are directly coupled to each other, a gap Gap between the LED 132 and the light guide plate 120 of the LED FPC 130 may be recognized. In addition, the light guide plate 120 and the LED FPC 130 are fastened in such a manner that the protrusion 121 of the light guide plate 120 is inserted into the escape groove 131 of the LED FPC 130. Since the gap Gap between the light guide plates 120 may be maintained at 0.05 mm or less, coupling with other components may be performed, thereby minimizing light leakage between the LED 132 and the light guide plate 120. have.

Next, as shown in FIG. 7B, the assembly of the light guide plate 120 and the LED FPC 130 is seated on the rear surface of the support main 110. As illustrated in FIG. 7C, at least one optical sheet 140 is formed by fitting the uneven portions 141 into the escape groove 131 into which the protrusion 121 is fitted so that the top and bottom of the optical sheet 140 are aligned. ) Is mounted on the upper surface of the light guide plate 120.

Meanwhile, in FIG. 4, the light guide plate is illustrated as including a plurality of protrusions 121 having a rectangular pillar shape, but this is merely an example for describing an exemplary embodiment of the present invention, and the shape of the protrusion 121 is various. Can be determined.

That is, as shown in FIG. 9, the light guide plate 120 may be formed to include a plurality of protrusions 121 having a triangular prism shape. As such, when the protrusion 121 is formed in a triangular prism shape, the protrusion 121 may be formed in a larger number than the rectangular pillar shape without invading the light emitting area of the LED 132. FPC 130 may be assembled.

As described above, according to the exemplary embodiment of the present invention, the light guide plate 120 and the LED FPC 130 are directly coupled to each other, so that the gap between the light guide plate 120 and the LED 132 is 0.05 mm or less. And an assembly of the LED FPC 130 may be seated on the support main 110. As a result, light leakage of the backlight unit is prevented, thereby reducing the luminance.

In addition, the at least one optical sheet 140 may form a plurality of concave and convex portions 141 on only one side, and may distinguish the upper and lower sides, instead of forming ear parts on both sides. Accordingly, it is possible to prevent the increase in the outermost size due to the ears on both sides, and to prevent light leakage due to the ears, thereby preventing the decrease in luminance.

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, and various substitutions, modifications, and changes may be made without departing from the technical spirit of the present invention.

1 is an exploded perspective view of a backlight unit according to the prior art.

2 is a plan view of an optical sheet included in the backlight unit illustrated in FIG. 1.

3 is an exploded perspective view of a backlight unit according to an embodiment of the present invention.

4 is a plan view of a light guide plate included in the backlight unit illustrated in FIG. 3.

FIG. 5 is a plan view of an LED flexible printed circuit board included in the backlight unit shown in FIG. 3.

6 is a plan view of an optical sheet included in the backlight unit illustrated in FIG. 3.

7 is a view illustrating an assembly process of a backlight unit according to an exemplary embodiment of the present invention.

8 is a cross-sectional view taken along the line 'I-II' in FIG. 7A.

9 is a plan view of a light guide plate according to another exemplary embodiment of the present invention.

<Description of identification numbers for the main parts of the drawings>

100: backlight unit 110: support main

120: light guide plate 121: projection

130: LED FPC 131: escape groove

132: LED 140: optical sheet

141: uneven portion

Claims (7)

A light guide plate including a plurality of protrusions protruding toward one side of the display panel; And a LED flexible printed circuit board having a plurality of LEDs generating the light and having a plurality of escape grooves on one side thereof so that the plurality of protrusions are inserted therein, respectively. The method of claim 1, When the plurality of protrusions are respectively inserted into the plurality of escape grooves, And the light guide plate and the LED flexible printed circuit board are assembled in such a manner that at least some of them overlap each other. The method of claim 1, A supporter main on which an assembly of the light guide plate and the LED flexible printed circuit board is mounted; And at least one optical sheet seated on an upper surface of the light guide plate to scatter or diffuse light emitted from the light guide plate and to transmit the light to the display panel. The method of claim 3, The at least one optical sheet And a plurality of uneven portions respectively inserted into the plurality of escape grooves into which the plurality of protrusions are inserted. The method of claim 4, wherein When the plurality of irregularities are respectively inserted into the plurality of escape grooves, The at least one optical sheet is a backlight unit, characterized in that assembled with the light guide plate to be seated on the upper surface of the light guide plate. The method of claim 1, And the plurality of protrusions have a rectangular pillar shape. The method of claim 1, The plurality of protrusions is a backlight unit, characterized in that the triangular prism shape.

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