KR20120014842A - Backlight unit and liquid crystal display device having same - Google Patents

Abstract

The present invention discloses a backlight unit capable of improving appearance quality.
The disclosed backlight unit includes a bottom cover having an upper surface opened, a light source unit disposed to be inclined with respect to a bottom surface of the bottom cover on an inner surface of the bottom cover, and a light source unit contacting the light source unit to discharge heat from the light source unit. And a light guide plate including an heat dissipation plate and an incident surface inclined horizontally with the light source unit on a side adjacent to the light source unit, and a reflective pattern of a transparent material reflecting a part of light on an upper surface adjacent to the incident surface.

Description

BACKLGIHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE THE SAME}

The present invention relates to a backlight unit, and more particularly, to a backlight unit capable of improving appearance quality and a liquid crystal display device having the same.

A CRT (cathode ray tube), which is one of the widely used display devices, is mainly used for monitors such as a TV, a measurement device, and an information terminal device. However, due to the weight and size of the CRT itself, Could not respond positively to the response of

As a solution to this problem, the liquid crystal display device has a tendency that its application range is gradually widening due to the features such as light weight, thinning, low power consumption driving. Accordingly, the liquid crystal display device is proceeding in the direction of large-sized, thin, and low power consumption in response to the demand of the user.

BACKGROUND ART A liquid crystal display device is a display device that displays an image by controlling the amount of light passing through a liquid crystal, and is widely used for advantages such as thinning and low power consumption.

The liquid crystal display panel has a structure in which the thin film transistor substrate and the color filter substrate are disposed to face each other, and the thin film transistor substrate and the color filter substrate are bonded by a seal pattern, and then liquid crystal is injected therebetween.

Since the liquid crystal display is not a self-luminous display, a backlight unit is provided below the liquid crystal display panel on which an image is displayed.

The backlight unit is divided into an edge method and a direct method according to the method of arranging the light sources.

Edge type backlight unit is composed of a light source provided on the side and a light guide plate for scattering the light incident from the light source, and is mainly used in small and medium-sized liquid crystal display device in favor of thinning.

The direct type backlight unit has a structure in which a plurality of light sources are disposed at regular intervals under the liquid crystal display panel to directly irradiate light directly under the liquid crystal display panel, and is mainly used for a large screen liquid crystal display device.

The backlight unit includes a lamp or a light emitting diode (LED) as a light source. Recently, light emitting diodes that are advantageous for low power consumption and slimming have been used.

The light emitting diode has a long lifespan, can be miniaturized and light in weight, has a strong light directivity, and can be driven at low voltage. In addition, it is resistant to shock and vibration, does not require preheating time and complicated driving circuits, and can be packaged in various forms, and is expected to replace incandescent lamps, fluorescent lamps, mercury lamps and existing white light sources in the next few years. In particular, the light emitting diode has a large energy band gap, and thus, light output of wavelength bands ranging from red to ultraviolet light is possible, and physical / chemical stability is excellent, and thus, high efficiency and high output have been attracting much attention. .

The edge type backlight unit provided with the light emitting diode has a problem in that luminance emitted from the light emitting diode is concentrated at one side where the light emitting diode is disposed, so that luminance such as a hot spot is uneven. In general, the edge type backlight unit has a structure in which a non-display area is enlarged to improve luminance non-uniformity in the side where the light emitting diode is disposed. .

An object of the present invention is to provide a backlight unit capable of improving appearance quality and a liquid crystal display device having the same.

The backlight unit according to an embodiment of the present invention,

A bottom cover with an upper surface opened; A light source unit disposed on an inner side surface of the bottom cover to be inclined with respect to a bottom surface of the bottom cover; A heat dissipation plate in contact with the light source unit for dissipating heat from the light source unit; And a light guide plate including an incident surface inclined horizontally with the light source unit on a side adjacent to the light source unit, and a reflective pattern of a transparent material reflecting a part of light on an upper surface adjacent to the incident surface.

In addition, the liquid crystal display device of the present invention,

A bottom cover with an upper surface opened; A light source unit disposed on an inner side surface of the bottom cover to be inclined with respect to a bottom surface of the bottom cover; A heat dissipation plate in contact with the light source unit for dissipating heat from the light source unit; A light guide plate including an incident surface inclined horizontally with the light source unit on a side adjacent to the light source unit and having a reflective pattern of a transparent material reflecting a part of light on an upper surface adjacent to the incident surface; And a liquid crystal display panel disposed on the light guide plate.

According to an exemplary embodiment of the present invention, an LCD including an edge type backlight unit includes a light source unit disposed on an inclined surface of a heat dissipation plate to have a predetermined inclination angle with respect to a bottom surface of a bottom cover, and the incident surface of the light guide plate corresponding thereto. Has an inclination angle inclined with respect to the lower surface of the light guide plate, and a reflection pattern reflecting a part of light is formed on one side of the light guide plate adjacent to the incident surface, thereby improving non-uniform brightness such as a hot spot and at the same time. This has the advantage of minimizing the appearance quality.

1 is an exploded perspective view illustrating a liquid crystal display device having an edge type backlight unit according to an exemplary embodiment of the present invention.
FIG. 2 is a cross-sectional view of the liquid crystal display taken along the line II ′ of FIG. 1.
3 is a cross-sectional view illustrating in detail the backlight unit in which the light emitting diode of FIG. 2 is disposed.
4 is a plan view illustrating the light guide plate of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the accompanying drawings, embodiments of the present invention will be described in detail.

FIG. 1 is an exploded perspective view illustrating a liquid crystal display device having an edge type backlight unit according to an exemplary embodiment of the present invention, and FIG. 2 is a view illustrating a liquid crystal display device cut along the line II ′ of FIG. 1. It is a cross section.

3 is a cross-sectional view illustrating in detail a backlight unit in which the light emitting diode of FIG. 2 is disposed, and FIG. 4 is a plan view illustrating a light guide plate of the present invention.

1 to 4, a liquid crystal display according to an exemplary embodiment of the present invention is provided with a liquid crystal display panel 110 on which an image is displayed, and is disposed under the liquid crystal display panel 110 to provide light. It includes a backlight unit 120 to.

In addition, the liquid crystal display of the present invention further includes a panel guide 118 supporting the lower edge of the liquid crystal display panel 110.

The liquid crystal display panel 110 includes a thin film transistor substrate 111 and a color filter substrate 112 bonded together to face a uniform cell gap, and a liquid crystal layer interposed between the two substrates.

Although not shown in detail in the drawings, the thin film transistor substrate 111 and the color filter substrate 112 will be described in detail. In the thin film transistor substrate 111, a plurality of gate lines and data lines cross each other to define pixels. A thin flim transistor (TFT) is provided at each of the crossing regions of the transistors, and is connected in a one-to-one correspondence with pixel electrodes mounted on each pixel. The color filter substrate 112 may include a color filter of R, G, and B colors corresponding to each pixel, a black matrix bordering each of them, and covering a gate line, a data line, a thin film transistor, and the like, and a common electrode covering all of them. Include.

A driving PCB 115 is provided at the edge of the liquid crystal display panel 110 to supply driving signals to the gate line and the data line.

The driving PCB 115 is electrically connected to the liquid crystal display panel 110 by a chip on film 117. Here, the COF 117 may be changed to a tape carrier package (TCP).

The backlight unit 120 disposed below the liquid crystal display panel 110 may include a bottom cover 190 having an upper surface opened, a light source unit 150 provided on an inner surface of the bottom cover 190, and emitting light; The liquid crystal display panel 110 includes a light guide plate 140 disposed in parallel with the light source unit 150 to convert linear light or point light into surface light, and light disposed below the light guide plate 140 and traveling below the light guide plate 140. The first reflecting sheet 170 reflecting in the direction of) and the optical sheets 130 disposed on the light guide plate 140 to diffuse and focus the light emitted from the light guide plate 140.

The light source unit 150 includes a printed circuit board 151 and a plurality of light emitting diodes 153 disposed on the printed circuit board 151 at regular intervals. Here, the printed circuit board 151 may be made of metal PCB having excellent thermal conductivity.

The backlight unit 120 of the present invention is in contact with the bottom cover 190 and the light source unit 150 to dissipate heat generated from the light source unit 150 and the lower portion of the panel guide 118 A second reflective sheet 180 is disposed on the surface and guides the light emitted from the light source unit 150 to the light guide plate 140.

The heat dissipation plate 160 may include an inclined surface 169 having a predetermined inclination angle on a side surface, first to third protrusions 161, 162 and 163 protruding outward from the inclined surface 169, and the first to third protrusions. First and second grooves 165, 167 formed by 161, 162, 163.

The inclined surface 169 of the heat dissipation plate 160 has an inclined angle inclined with respect to the bottom surface of the bottom cover 190. The inclination angle of the inclined surface 169 is 45 degrees to 89 degrees based on the bottom surface of the bottom cover 190.

The light source unit 150 is disposed on the inner surface of the inclined surface 169. That is, the inner surface of the inclined surface 169 is in surface contact with the printed circuit board 151. That is, the light source unit 150 is disposed on the inclined inclined surface 169 of the heat dissipation plate 160 and inclined based on the bottom surface of the bottom cover 190.

The first to third protrusions 161, 162 and 163 and the first and second grooves 165 of the heat dissipation plate 160 have a function of maximizing heat dissipation by increasing the end area of the heat dissipation plate 160.

The bottom cover 190 has a bent structure to have a receiving groove shape on the side surface corresponding to the heat dissipation plate 160.

One side surface 191 of the bottom cover 190 corresponding to the heat dissipation plate 160 is in contact with the second and third protrusions 162 and 163.

In detail, one side surface 191 of the bottom cover 190 is in surface contact with the bottom surface of the second protrusion 162 and is in surface contact with the outer surface of the second protrusion 163.

The heat dissipation plate 160 and the bottom cover 190 are coupled in the same structure as described above to expose the first and second protrusions 161 and 162 and the first groove 165 of the heat dissipation plate 160 from the outside. The heat dissipation plate 160 of the present invention may maximize the heat dissipation effect by the convection of the outside air by the first and second protrusions 161 and 162 and the first groove 165 exposed to the outside.

The light guide plate 140 of the present invention defines one surface corresponding to the light source unit 150 as an incident surface 141 through which light is incident, and the incident surface 141 is a tilted inclination angle of the light source unit 150. It is formed to be inclined in parallel. That is, the incident surface 141 has a constant inclination angle with respect to the lower surface of the light guide plate 140.

The upper surface of the light guide plate 140 adjacent to the incident surface 141 is formed with a reflective pattern 143 reflecting a part of the light emitted from the light source unit 150.

The reflective pattern 143 is formed by densely applying an acrylic transparent material, and reflects a part of the light incident from the light source unit 150 vertically to the inside of the light guide plate 140 so that a hot spot of an area adjacent to the light source unit 150 is formed. It has a function to improve hot spots.

The reflective pattern 143 has a first overlapping region o1 overlapping the second reflective sheet 180.

In addition, the reflective pattern 143 has a second overlapping region o2 overlapping with one side of the optical sheets 130.

The first reflective sheet 170 of the present invention is disposed on the bottom cover 190 and extends to an area where the light source unit 150 is disposed to guide light from the light source unit 150 into the light guide plate 140. .

That is, the first reflective sheet 170 has a region overlapping the heat dissipation plate 160.

In the liquid crystal display including the edge-type backlight unit 120 according to the exemplary embodiment described above, the light source unit 150 is disposed on the inclined surface 169 of the heat dissipation plate 160, and thus the bottom cover 190 is disposed. It has a constant inclination angle with respect to the lower surface of the, the incident surface 141 of the light guide plate 140 corresponding to this has a tilt angle inclined with respect to the lower surface of the light guide plate 140, the light guide plate adjacent to the incident surface 141. The reflective pattern 143 reflecting a part of the light is formed on the upper side of the 140, thereby improving non-display area B while minimizing the non-display area B such as hot spots and improving appearance quality. Has

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

140: light guide plate 141: incident surface
143: reflection pattern 150: light source unit
160: heat dissipation plate 161: first protrusion
162: second protrusion 163: third protrusion
165: first groove 167: second groove
169: slope

Claims (16)

A bottom cover with an upper surface opened;
A light source unit disposed on an inner side surface of the bottom cover to be inclined with respect to a bottom surface of the bottom cover;
A heat dissipation plate in contact with the light source unit for dissipating heat from the light source unit; And
And a light guide plate including an incident surface inclined horizontally with the light source unit on a side adjacent to the light source unit, and a reflective pattern of a transparent material reflecting a part of light on an upper surface adjacent to the incident surface. . The method according to claim 1,
The heat dissipation plate,
An inclined surface having a constant inclination angle on the side surface;
First to third protrusions protruding outwardly from the inclined surface; And
And first and second grooves formed by the first to third protrusions. The method of claim 2,
The inclination angle of the inclined surface is a backlight unit, characterized in that consisting of 45 degrees to 89 degrees. The method of claim 2,
The light source unit includes a metal PCB and a plurality of light emitting diodes mounted on the metal PCB, wherein the metal PCB is in surface contact with the inclined surface. The method of claim 2,
One side surface of the bottom cover is in surface contact with the bottom surface of the second protrusion, the backlight unit, characterized in that the surface contact with the outer surface of the third protrusion. The method according to claim 1,
The reflective pattern has a region overlapping with one side of the optical sheets disposed on the light guide plate. The method according to claim 1,
A reflective sheet is disposed below the light guide plate, and the reflective sheet extends to a region where the light source unit is disposed. A bottom cover with an upper surface opened;
A light source unit disposed on an inner side surface of the bottom cover to be inclined with respect to a bottom surface of the bottom cover;
A heat dissipation plate in contact with the light source unit for dissipating heat from the light source unit;
A light guide plate including an incident surface inclined horizontally with the light source unit on a side adjacent to the light source unit and having a reflective pattern of a transparent material reflecting a part of light on an upper surface adjacent to the incident surface; And
And a liquid crystal display panel disposed on the light guide plate. The method of claim 8,
The heat dissipation plate,
An inclined surface having a constant inclination angle on the side surface;
First to third protrusions protruding outwardly from the inclined surface; And
And first and second grooves formed by the first to third protrusions. 10. The method of claim 9,
And an inclination angle of the inclined surface is 45 degrees to 89 degrees. 10. The method of claim 9,
The light source unit includes a metal PCB and a plurality of light emitting diodes mounted on the metal PCB, wherein the metal PCB is in surface contact with the inclined surface. 10. The method of claim 9,
And one side surface of the bottom cover is in surface contact with a bottom surface of the second protrusion, and in surface contact with an outer surface of the third protrusion. The method of claim 8,
And the reflective pattern has a region overlapping with one side of the optical sheets disposed on the light guide plate. The method of claim 8,
A first reflective sheet is disposed below the light guide plate, and the first reflective sheet extends to a region where the light source unit is disposed. The method of claim 14,
And a panel guide for supporting the liquid crystal display panel, and a second reflecting sheet for guiding light emitted from the light source unit to the light guide plate below the panel guide. The method of claim 15,
And the reflective pattern has a region overlapping the second reflective sheet.

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