KR101839335B1 - Back light unit and liquid crystal display device using the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit and a liquid crystal display device using the backlight unit, which can prevent the optical sheet deformation of the backlight unit applied to the large-screen liquid crystal display device and the light distribution change due to the deformation of the optical sheet, A backlight unit includes a plurality of light sources for generating light; A light source fixing unit mounted with the plurality of light sources and fixedly arranged on an inner side surface of the bottom cover; A first diffusion plate for receiving light from each of the light sources to the side incidence surface, A second diffusion plate disposed on the front surface of the first diffusion plate for emitting light incident from the first diffusion plate on the back surface to the front surface and changing the incident light from the side surface to a front surface to output light; And a plurality of optical sheets disposed on the front surface of the second diffuser plate and vertically emitting light incident from the second diffuser plate on the back surface.

Description

BACK LIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE USING THE SAME [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit, and more particularly, to a backlight unit which prevents a change in light distribution due to deformation of an optical sheet and deformation of an optical sheet of a backlight unit applied to a large-screen liquid crystal display device, Unit and a liquid crystal display using the same.

BACKGROUND ART Demands for video display devices have been increasing in various forms as an information society has developed. In recent years, a liquid crystal display, a field emission display, a plasma display panel, Various flat panel display devices such as a light emitting display are utilized.

Of the above flat panel display devices, liquid crystal display devices are widely used because they can operate at low power and have excellent image quality. In a liquid crystal display device, a liquid crystal panel composed of two substrates facing each other and liquid crystal interposed therebetween is used. Here, the liquid crystal panel displays an image by changing the arrangement of the liquid crystal by the electric field generated between the liquid crystal. Such a liquid crystal panel corresponds to a non-light emitting type display panel and receives light from a backlight unit to display an image. Generally, the backlight unit is divided into an edge type backlight unit and a direct-type backlight unit depending on the position of the light source.

BACKGROUND ART [0002] In recent years, backlight units have also become larger and thinner in accordance with the trend toward larger and thinner liquid crystal display devices. In the backlight unit, a light emitting diode, which is advantageous in terms of power consumption, weight, luminance, etc., is mainly used as a light source instead of a conventional fluorescent lamp, and an edge type Backlight unit is mainly used.

However, while the backlight unit and the liquid crystal display device having the backlight unit are enlarged, the thickness of the backlight unit is made thinner, resulting in defects due to heat generation of the light sources. In other words, although the number of light sources applied to the backlight unit increases due to the trend toward larger size of the backlight unit and the liquid crystal display device, the distance between the light sources and the optical sheets provided in the backlight unit becomes closer to each other. Accordingly, there has been a problem that at least one optical sheet is deformed according to the heat generation temperature of the light sources, and various problems arise in that the light distribution is irregularly changed, for example, a bright line appears due to deformation of the optical sheets.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a backlight unit capable of preventing optical sheet deformation of a backlight unit applied to a large- And an object of the present invention is to provide a backlight unit and a liquid crystal display using the same.

According to an aspect of the present invention, there is provided a backlight unit including: a plurality of light sources for generating light; A light source fixing unit mounted with the plurality of light sources and fixedly arranged on an inner side surface of the bottom cover; A first diffusion plate for receiving light from each of the light sources to the side incidence surface, A second diffusion plate disposed on the front surface of the first diffusion plate for emitting light incident from the first diffusion plate on the back surface to the front surface and changing the incident light from the side surface to a front surface to output light; And a plurality of optical sheets disposed on the front surface of the second diffuser plate and vertically emitting light incident from the second diffuser plate on the back surface.

The first diffusing plate is formed thicker or thicker than the second diffusing plate, and a plurality of first refraction patterns are formed in a concave shape on the back surface of the first diffusing plate, Is diffused in the direction of the back surface of the second diffuser plate disposed on the front surface and irradiated.

The second diffusion plate is formed to be thinner than or equal to the thickness of the first diffusion plate. A plurality of second refraction patterns are formed in a concave shape on the back surface of the second diffusion plate, Diffused light is diffused toward the front direction and irradiated.

Wherein the plurality of optical sheets are composed of at least one diffusion sheet excluding a prism sheet and at least one polarizing sheet and a plurality of sheets in order to adjust the optical path diffused by the first and second diffuser plates .

Each of the plurality of first and second refraction patterns is formed so that the density of the first and second refraction patterns becomes higher as the center of the back surface is closer to the outer surface of the back surface of the first and second diffusion plates.

The plurality of first and second refracting patterns are formed such that the density of the first and second refracting patterns decreases as the distance from the light sources to the adjacent light sources increases.

And a plurality of horizontal lenticules are further formed on the front surface of the first diffusion plate.

According to another aspect of the present invention, there is provided a liquid crystal display device including: a liquid crystal panel having a plurality of pixel regions to display an image; A panel guide for seating and fixing the liquid crystal panel; A top case including a front surface of the liquid crystal panel and configured to surround the panel guide; And a backlight unit including at least one of various technical features as described above for irradiating light to the liquid crystal panel.

The backlight unit of the present invention having the above characteristics and the liquid crystal display device using the same can further improve the reliability of the product by preventing the optical sheet deformation and the light distribution change of the large backlight unit applied to the large- . Further, by improving the central luminance and the uniformity of the backlight unit, the luminous efficiency can be further improved.

1 is an exploded perspective view schematically showing a backlight unit and a liquid crystal display device using the same according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating a state in which the AA 'cross section in FIG. 1 is assembled. FIG.
3 is a cross-sectional view showing a BB 'cut plane of the first and second diffusion plates shown in FIG. 1;
FIG. 4 is a perspective view of the first and second diffuser plate back surfaces shown in FIG. 1 so as to face upward. FIG.

Hereinafter, a backlight unit according to an embodiment of the present invention and a liquid crystal display using the same will be described in detail with reference to the accompanying drawings.

1 is an exploded perspective view schematically showing a backlight unit and a liquid crystal display device using the same according to an embodiment of the present invention.

The liquid crystal display device of the present invention shown in Fig. 1 comprises a backlight unit 2; A panel guide 90; And includes a liquid crystal panel 100 and a top case 130.

The liquid crystal panel 100 is stacked on the panel support portion of the panel guide 90 to adjust the transmittance of light from the backlight unit 2 to display an image. The liquid crystal panel 100 includes a liquid crystal (not shown) formed between a lower substrate 102 and an upper substrate 104, a lower substrate 102 and an upper substrate 104, a lower substrate 102, And a spacer (not shown) that maintains a constant distance between the electrodes 104 and 104.

The upper substrate 104 is further provided with blue, red, and green color filters, a black matrix, a common electrode, and the like.

The lower substrate 102 includes a thin film transistor formed in each cell region defined by data lines and gate lines, and a pixel electrode connected to the thin film transistor. The thin film transistor switches the image signal supplied from the data line to the pixel electrode in response to the gate-on voltage supplied from the gate line. Here, the common electrode formed on the upper substrate 104 may be formed on the lower substrate 102 depending on the mode of the liquid crystal.

A non-display region of the lower substrate 102 is provided with a data pad region connected to each of the data lines and a gate pad region connected to each of the gate lines.

In the data pad area, a plurality of data circuit films 110 mounted with a data integrated circuit 112 for supplying image signals to the data lines are attached. Each data circuit film 110 may be a tape carrier package or a chip on film. Each data circuit film 110 supplies a data signal or the like from a data printed circuit board (not shown) to the data integration circuit 112 and supplies the image signal output from the data integration circuit 112 to each data line do. On the other hand, the data integrated circuit 112 may be mounted on the lower substrate 102 by a chip on glass method. In this case, the data integrated circuit 112 mounted on the lower substrate 102 receives a data signal or the like from the data printed circuit board through the data circuit film 110.

In the gate pad region, a plurality of gate circuit films 120 mounted with gate integrated circuits 122 for supplying gate-on voltages to the gate lines are attached. Each gate circuit film 120 may be a tape carrier package or a chip-on film or the like. Each gate circuit film 120 supplies a gate control signal supplied from the data printed circuit board through the data circuit film 110 and the lower substrate 102 to the gate integrated circuit 122 and supplies the gate control signal to the gate integrated circuit 122 To the respective gate lines. Here, the gate integrated circuit 122 may be mounted on the lower substrate 102 by a chip on glass method, or may be formed on the lower substrate 102 together with the manufacturing process of the thin film transistor.

The panel guide 90 is mounted on the seating portion of the bottom cover 10 so as to cover the front edge and sides of the diffusion plate 70 and the plurality of optical sheets 80 and to cover the side surface of the bottom cover 10. [ The panel guide 90 has a panel support portion for supporting the liquid crystal panel 100. The panel supporting portion is formed so as to support the rear surface non-display region and the side surface of the liquid crystal panel 100.

The top case 130 is bent so as to enclose the front non-display area of the liquid crystal panel 100 and the side surface of the panel guide 90. At this time, the top case 130 can be fastened and fixed to the fastening ring of the panel guide 90 surrounding the side surface of the bottom cover 10. In recent years, the thickness and the forming width of the panel guide 90 are also becoming thinner and narrower in forming the size of the top case 130, for example, the thickness of the bezel and the front surface width.

2 is a cross-sectional view showing a state in which the A-A 'cut plane of FIG. 1 is assembled.

1 and 2, the backlight unit 2 includes a plurality of light sources 40 for generating light; A light source fixing part 41 mounted with a plurality of light sources 40 and fixedly arranged on an inner side surface of the bottom cover 10; A first diffusion plate (70) which receives light from each light source (40) to the side incidence surface and changes the traveling direction of the light to the front and emits the light; The light diffusing plate 70 is disposed on the front surface of the first diffuser plate 70 so as to emit light incident from the first diffuser plate 70 on the back surface to the front surface and to change the incident light from the side light incident surface 2 diffusion plate 72; And a plurality of optical sheets 80 disposed on the front surface of the second diffusion plate 72 and vertically emitting light incident from the second diffusion plate 72 on the rear surface.

The backlight unit 2 is formed of a reflective material so as to cover all the inner surfaces of the bottom cover 10 and transmits light from the plurality of light sources 40 and the first diffusion plate 70 to the first diffusion plate And a reflective sheet 78 reflecting the light toward the front surface of the light guide plate 70.

As each of the light sources 40, a light emitting diode (LED) which is advantageous in terms of power consumption, weight, luminance, etc. can be mainly used. The light sources 40 may include only white LEDs to emit white light, and red, green, and blue LEDs may be combined to emit white light. Each of the light sources 40 is detachably mounted on the light source fixing portion 41 and positioned to face the side light incidence surfaces of the first diffusion plate 70 and the second diffusion plate 72. Each of the plurality of light sources 40 is illuminated by the light source driving power source supplied through the light source fixing unit 41 and irradiates the light to the side light incidence surfaces of the first and second diffusion plates 70 and 72.

The light source fixing unit 41 is provided with the light sources 40 fixed to one side of the bottom cover 10 and supplies the light source driving power Vin from the outside to the light sources 40. In other words, the light source fixing unit 41 is formed of a printed circuit board or the like, and when the light sources 40 are mounted, a light source driving power transmitted from the outside through a pattern or wiring formed thereon is supplied to each light source 40 ).

The first diffusion plate 70 is provided on the inner bottom surface of the bottom cover 10 having a rectangular frame shape. At this time, the side light incidence surface of the first diffusion plate 70 is disposed on the front surface of the light source fixing portion 41. That is, the side light incident surface of the first diffusion plate 70 faces the light source fixing portion 41. The first diffusing plate 70 is thicker or has the same thickness as the second diffusing plate 72. A plurality of first refraction patterns 70a are formed on the back surface of the first diffusing plate 70 in a concave shape And the light irradiated to the side incidence surface is diffused and diffused toward the back surface of the second diffuser plate 72 disposed on the front surface. In this case, a part of the light may be emitted to the back surface or the side surface of the first diffusion plate 70. In this case, the light is reflected by the reflection sheet 78 disposed on the back surface and the side surface of the first diffusion plate 70, Light is irradiated in the backward direction.

The second diffusion plate 72 is disposed on the front surface of the inner first diffusion plate 70 of the bottom cover 10 having a rectangular frame shape. At this time, the side light incident surface of the second diffusion plate 72 is disposed on the front surface of the light source fixing portion 41 together with the side light entrance surface of the first diffusion plate 70. That is, the side light incidence surface of the second diffuser plate 72 is also located facing the light source fixing portion 41. The second diffusion plate 72 is formed to be thinner or the same thickness as the first diffusion plate 70 and a plurality of second refraction patterns 72a are formed on the back surface of the second diffusion plate 72 in a concave shape And the light incident on the side incidence surface and the back surface is diffused in the front direction and irradiated.

The plurality of optical sheets 80 diffuse through the first and second diffuser plates 70 and 72 and adjust the optical path so that the incident light is perpendicularly irradiated to the liquid crystal panel 100. The present invention further includes a second diffuser plate 72 having a plurality of second diffraction patterns 72a in addition to the first diffuser plate 70 so that the prism sheet is most vulnerable to the heat generation of each light source 40 It does not have to be. That is, the plurality of optical sheets 80 according to the present invention include at least one diffusing sheet 84 excluding the prism sheet and at least one diffusing sheet 84 (not shown) for adjusting the optical path diffused by the first and second diffusing plates 70 and 72 A single polarizing sheet 86 and a protective sheet (not shown). At this time, the types of sheets to be stacked and the order in which the sheets are stacked can be converted and set according to the intended use of the backlight unit 10. [

The backlight unit 2 further includes a light source driving circuit unit (not shown) that generates a light source driving power source and drives the light sources 40. The backlight unit 2 includes a light source fixing unit 41, Thereby supplying driving power. Here, in the case of the light source driving circuit unit, the external power source, which is composed of at least one inverter or switching circuits, is converted into a DC power source to generate a light source driving power source. The generated light source driving power is supplied to each of the light sources 40 in accordance with the driving timing of the liquid crystal panel 100 and the like. As described above, the backlight unit 2 generates light by illuminating the plurality of light sources 40 with the light source driving power supplied from the light source driving circuit unit, and irradiates the liquid crystal panel 100 and the like.

3 is a cross-sectional view of the first and second diffuser plates taken along the line B-B 'in FIG. 4 is a perspective view of the back surface of the first and second diffusion plates shown in FIG.

3 and 4, a plurality of refraction patterns for increasing the refraction efficiency of light incident on the side light-incident portion, that is, a plurality of first (first) and second A refraction pattern 70a and a plurality of second refraction patterns 72a are formed. Here, the plurality of first and second refraction patterns 70a and 72a may be formed in various sizes and shapes through a separate laser processing process. At this time, it is preferable that each of the first and second refraction patterns 70a and 72a is formed so as to improve the central luminance and luminance uniformity of the backlight unit 2. To this end, the plurality of first and second refraction patterns 70a and 72a may be formed so that the density of the first and second refraction patterns 70a and 72a becomes higher as they are closer to the center of the back surface from the outer surface of the back surface of each of the first and second diffusion plates 70 and 72 have. Each of the plurality of first and second refraction patterns 70a and 72a may be formed so that the density of the first and second refraction patterns 70a and 72a decreases as the distance from the light sources 40 to the light sources 40 is greater. A horizontal lenticular 70b may be further formed on the front surface of the first diffusion plate 70. When the horizontal lenticular 70b is further formed, the luminance uniformity of the first and second diffusion plates 70 and 72 may be further improved. Can be improved.

As described above, in the case of the large backlight unit applied to the large-screen liquid crystal display device of the present invention, a plurality of diffusion plates 70 and 72 can be applied instead of using a weak prism sheet, 80) and thus a change in light distribution can be prevented.

Further, as shown in Table 1, the plurality of first and second refraction patterns 70a and 72a are formed so that the density of the first and second refraction patterns 70a and 72a is high at the center of the back surface of each of the first and second diffusion plates 70 and 72 , The central luminance and luminance uniformity of the backlight unit 2 can be improved and the luminous efficiency can be further improved.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Will be apparent to those of ordinary skill in the art.

Claims (8)

A plurality of light sources for generating light;
A light source fixing unit mounted with the plurality of light sources and fixedly arranged on an inner side surface of the bottom cover;
A plurality of first refraction patterns each having an elliptical shape in the shape of an ellipse and concave in a direction parallel to the light incidence surface are provided on a rear surface of the light guiding plate in such a manner that light is incident from each light source to the side incidence surface, A first diffusion plate;
And a second diffusion plate disposed on the front surface of the first diffusion plate for outputting the light incident from the first diffusion plate on the back to the front surface and changing the incident light from the side light incident surface to the front surface, A second diffusion plate having a plurality of second refraction patterns recessed in a direction parallel to the light incidence surface in an elliptical shape; And
And a plurality of optical sheets disposed on a front surface of the second diffuser plate and vertically emitting light incident from the second diffuser plate on the back surface,
Wherein a plurality of light sources are arranged side by side between the first diffusion plate and the second diffusion plate in a direction perpendicular to the light incidence surface to emit light incident from the light incidence surface or the first diffusion plate toward the second diffusion plate ≪ / RTI &
Wherein the first refraction pattern and the second refraction pattern are disposed perpendicularly to the horizontal lenticular. The method according to claim 1,
The first diffusion plate
Wherein the first diffusing plate is formed thicker or thicker than the second diffusing plate and diffuses the light irradiated to the side incidence surface in the direction of the back surface of the second diffuser plate disposed on the front surface and irradiates the backlight unit. delete The method according to claim 1,
The plurality of optical sheets
And at least one diffusion sheet excluding a prism sheet and at least one polarizing sheet and a plurality of sheets among the protective sheet for adjusting the optical path diffused by the first and second diffuser plates. 5. The method of claim 4,
Each of the plurality of first and second refraction patterns
Wherein the first diffusion plate and the second diffusion plate are formed so as to have a higher density as they are closer to the center of the back surface from the outer surface of the back surface of each of the first and second diffusion plates. 6. The method of claim 5,
Each of the plurality of first and second refraction patterns
And the density of the light is reduced as the distance from the light sources to the adjacent light sources is greater. delete A liquid crystal panel having a plurality of pixel regions to display an image;
A panel guide for seating and fixing the liquid crystal panel;
A top case including a front surface of the liquid crystal panel and configured to surround the panel guide; And
And a backlight unit including the technical structure of any one of Claims 1 to 2 and Claims 4 to 6 for irradiating light to the liquid crystal panel.

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