KR101730331B1 - Optical sheet, backlight unit and liquid crystal display device using the same - Google Patents

Abstract

The present invention relates to an optical sheet, a backlight unit and a liquid crystal display using the optical sheet, which can improve the light-condensing efficiency and brightness and reduce the production cost. A plurality of lens patterns formed on the base member; And a plurality of prism patterns formed in a remaining region of the base member on which the plurality of lens patterns are not formed.

Description

TECHNICAL FIELD [0001] The present invention relates to an optical sheet, a backlight unit using the optical sheet, and a liquid crystal display device using the optical sheet. BACKGROUND OF THE INVENTION [0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a backlight unit and a liquid crystal display, and more particularly, to an optical sheet capable of improving light-condensing efficiency and luminance and reducing a production cost, and a backlight unit and a liquid crystal display .

2. Description of the Related Art In recent years, various flat panel display devices that can reduce weight and volume, which are disadvantages of cathode ray tubes (CRTs), are emerging. Examples of such flat panel display devices include a liquid crystal display, a field emission display, a plasma display panel, and a light emitting display.

Among flat panel displays, a liquid crystal display device includes a liquid crystal panel composed of a plurality of liquid crystal cells and a plurality of control switches for switching a video signal to be supplied to each of the liquid crystal cells, The amount of transmitted light is adjusted to display a desired image.

1 is a view showing a conventional backlight unit.

Referring to FIG. 1, a conventional backlight unit includes a light source 10; A reflective sheet (20); A diffusion plate (30); A lower diffusion sheet 40; First and second prism sheets (50, 60); And an upper diffusion sheet (70).

The light source 10 generates light according to the driving of each of the plurality of lamps disposed at a predetermined interval on the lower surface of the diffusion plate 30, and irradiates the diffusion plate 30 with light.

The reflective sheet 20 is disposed on the lower surface of the light source 10 and reflects the light incident from the light source 10 toward the diffusion plate 30 to minimize the loss of light.

The diffusion plate 30 is disposed on the light source 10 to diffuse the light emitted from the light source 10 and irradiate the light onto the lower diffusion sheet 40.

The lower diffusion sheet 40 is disposed on the diffusion plate 30 and diffuses the light emitted from the diffusion plate 30 into the entire area to irradiate the first prism sheet 50.

The first prism sheet 50 is disposed on the lower diffusion sheet 40. 2A, the first prism sheet 50 condenses the light emitted from the lower diffusion sheet 40 in a first direction (e.g., the X-axis direction) to form a second prism sheet 60 ). To this end, the first prism sheet 50 has a plurality of prism mountains 52 formed in parallel to each other with a predetermined interval along the first direction.

The second prism sheet (60) is disposed on the first prism sheet (50). 2B, the second prism sheet 60 is configured to condense the light emitted from the first prism sheet 50 in a second direction (e.g., the Y-axis direction) perpendicular to the first direction And irradiates the upper diffusion sheet 70. To this end, the second prism sheet 60 has a plurality of prism mountains 62 formed in parallel to each other with a predetermined interval along the second direction.

The upper diffusion sheet 70 is disposed on the second prism sheet 60 and diffuses light radiated from the second prism sheet 60 into the entire area to irradiate the liquid crystal display panel (not shown).

Such a conventional backlight unit can concentrate light by using two prism sheets 50 and 60, thereby improving the light-condensing efficiency and increasing the brightness.

However, the conventional backlight unit has the following problems.

Second, although the light-condensing efficiency and the luminance can be improved by using the two prism sheets 50 and 60, there is a problem that the production cost increases due to the use of the expensive prism sheets 50 and 60.

Second, the light in the first direction is condensed through the first prism sheet 50, and the light in the second direction is condensed through the second prism sheet 60, so that the luminance at the viewing angle There is a problem that the change is increased and a feeling of impression is generated.

Third, since the expensive diffusion sheet 70 needs to be used in order to solve the problems associated with the use of the two prism sheets 50 and 60, the production cost increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical sheet capable of improving the light-condensing efficiency and brightness and reducing the production cost, and a backlight unit and a liquid crystal display device using the optical sheet.

According to an aspect of the present invention, there is provided an optical sheet comprising: a base member; A plurality of lens patterns formed on the base member; And a plurality of prism patterns formed in a remaining region of the base member on which the plurality of lens patterns are not formed.

According to an aspect of the present invention, there is provided a backlight unit including: a light source for generating light; A diffusion plate for diffusing light emitted from the light source; An optical sheet disposed on the diffuser plate for condensing and diffusing light emitted from the diffuser plate; And an upper diffusion sheet disposed on the optical sheet and diffusing light emitted from the optical sheet, the optical sheet comprising: a base member; A plurality of lens patterns formed on the base member; And a plurality of prism patterns formed in a remaining region of the base member on which the plurality of lens patterns are not formed.

According to an aspect of the present invention, there is provided a liquid crystal display device including: a liquid crystal display panel for displaying an image by adjusting a light transmittance; And a backlight unit for emitting light to the liquid crystal display panel, wherein the backlight unit comprises: a light source for generating light; A diffusion plate for diffusing light emitted from the light source; And a plurality of lens patterns formed on the base member and a plurality of lens patterns formed on the remaining region of the base member on which the plurality of lens patterns are not formed for diffusing and condensing light emitted from the diffusing plate, An optical sheet including a prism pattern; And an upper diffusion sheet disposed on the optical sheet for diffusing light emitted from the optical sheet.

As described above, the optical sheet according to the present invention, the backlight unit using the same, and the liquid crystal display device have the following effects.

First, by using an optical sheet including a plurality of lens patterns formed on the base member and a plurality of prism patterns formed on the entire void space between the plurality of lens patterns, the light collection efficiency and brightness can be improved, and the contrast ratio and visual sensitivity There is an effect that it can be improved.

Second, since the expensive prism sheet is not used, the production cost can be reduced.

1 is a view showing a conventional backlight unit.
2A is a diagram showing the brightness of light converged by the first prism sheet shown in FIG.
FIG. 2B is a view showing the luminance of light converged by the second prism sheet shown in FIG. 1. FIG.
2C is a diagram showing the brightness of light passing through the first and second prism sheets shown in FIG.
3A is a perspective view for explaining an optical sheet according to a first embodiment of the present invention.
3B is a plan view for explaining an optical sheet according to the first embodiment of the present invention.
4A is a cross-sectional view for explaining a cross section cut along the line AA shown in FIG. 3B.
FIG. 4B is a cross-sectional view illustrating another embodiment of a cross section cut along the line AA shown in FIG. 3B.
FIG. 5 is a view for explaining a cross-sectional shape of the prism pattern shown in FIGS. 3A to 4B. FIG.
FIG. 6B is a cross-sectional view illustrating another embodiment of a cross section cut along the line AA shown in FIG. 3B.
7A is a plan view for explaining an optical sheet according to a second embodiment of the present invention.
FIG. 7B is a cross-sectional view for explaining a cross section cut along the BB line shown in FIG. 7A. FIG.
8 is a plan view for explaining an optical sheet according to a third embodiment of the present invention.
9 is a perspective view schematically illustrating a backlight unit according to an embodiment of the present invention.
10 is a perspective view schematically illustrating a liquid crystal display device according to an embodiment of the present invention.
11A is a graph showing luminance characteristics when a black image is displayed on a liquid crystal display panel using a backlight unit including an optical sheet according to the present invention.
11B is a diagram showing luminance characteristics when a white image is displayed on a liquid crystal display panel using a backlight unit including an optical sheet according to the present invention.
11C is a graph showing the contrast ratio characteristics of the liquid crystal display panel driven by the backlight unit including the optical sheet according to the present invention.

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

FIG. 3A is a perspective view for explaining an optical sheet according to a first embodiment of the present invention, and FIG. 3B is a plan view for explaining an optical sheet according to the first embodiment of the present invention.

Referring to FIGS. 3A and 3B, an optical sheet 100 according to a first embodiment of the present invention includes a base member 110; A plurality of lens patterns 120 formed on the base member 110; And a plurality of prism patterns 130 formed on the remaining regions of the base member 110 where the plurality of lens patterns 120 are not formed.

The base member 110 is formed of a transparent material so that light incident from the outside can be transmitted. For example, the base member 110 may be a film made of polyester (PET).

Each of the plurality of lens patterns 120 may be convexly formed to have a hemispherical shape on the upper surface of the base member 110. That is, each of the plurality of lens patterns 120 may be formed to protrude hemispherically. At this time, each of the plurality of lens patterns 120 may be formed to be regularly arranged on the entire upper surface of the base member 110, but may be irregularly arranged.

Each of the plurality of lens patterns 120 diffuses the light incident on the hemispherical surface through the base member 110 and condenses the light uniformly. For this purpose, the plurality of lens patterns 120 may be made of acrylic, polycarbonate, polypropylene, polyethylene, or polymethylmethacrylate.

Each of the plurality of prism patterns 130 is formed in the remaining region of the base member 110 where the plurality of lens patterns 120 are not formed.

More specifically, each of the plurality of prism patterns 130 is disposed on the other side of the base member 110 in which the plurality of lens patterns 120 are not formed so as to be parallel to the first direction (for example, Are formed in a stripe shape in the region. 4A and 4B, depending on the size of the empty space provided between the lens patterns 120 or the width of the prism pattern 130, at least one A prism pattern 130 may be formed. Here, the plurality of prism patterns 130 are preferably formed to have a lower height than the lens pattern 120.

As shown in FIGS. 5A to 5E, the plurality of prism patterns 130 includes an equilateral triangle a, an equilateral triangle b having a curved surface at an apex, an isosceles triangle c, An isosceles triangle d formed, and an isosceles triangle e formed by a curved surface on an inclined plane.

Each of the plurality of prism patterns 130 uses an inclined surface to condense the incident light through the remaining region of the base member 110 where the plurality of lens patterns 120 are not formed. That is, light vertically incident by the base member 110 is totally reflected by the inclined surface of the prism pattern 130, is recycled and is condensed, and light incident at an angle is incident on the inclined surface of the prism pattern 130 And is condensed.

4A or 4B, the optical sheet 100 according to the first embodiment of the present invention includes a diffusion bead 140 formed on the lower surface of the base member 110; And a coating layer 150 formed on the entire lower surface of the base member 110 including the diffusion beads 140.

The diffusion beads 140 are spherical fine particles made of inorganic materials such as glass, talc, aluminum oxide and titanium dioxide, or organic materials such as polystyrene, polycarbonate and polymethyl methacrylate. At this time, the fine particles such as talc, aluminum oxide, and titanium dioxide have a function of diffusing light by reflecting light on the surface without transmitting light, and fine particles such as glass, polystyrene, polycarbonate, polymethyl methacrylate, And has a function of transmitting or diffracting light to change and diffuse the light path.

The coating layer 150 is coated on the entire lower surface of the base member 110 to fix the diffusion beads 140. At this time, the coating layer 150 may be made of a transparent resin which does not hinder the light transmission efficiency.

6, the optical sheet 100 according to the first embodiment of the present invention may be formed in the same manner as the optical sheet 100 of the first embodiment except that the optical sheet 100 is formed on the lower surface of the base member 110 in place of the diffusion beads 140 and the coating layer 150 And may include a plurality of reflection patterns 160.

The plurality of reflection patterns 160 are concave on the lower surface of the base member 110 so as to overlap the boundary portion between the lens pattern 120 and the prism pattern 130. At this time, the plurality of reflection patterns 160 may be formed to have a triangular cross section. The plurality of reflection patterns 160 reflects light incident at a predetermined angle and proceeds to the upper surface of the base member 110.

6, a plurality of reflection patterns 160 are formed concavely on the lower surface of the base member 110. However, the present invention is not limited thereto, and a plurality of reflection patterns 160 may be formed on the lower surface of the base member 110, . In addition, the plurality of reflection patterns 160 may be formed in various shapes other than the triangular cross section.

In the optical sheet 100 according to the first embodiment of the present invention, a plurality of prism patterns 130 are formed in the remaining regions of the base member 110 where the plurality of lens patterns 120 are not formed, And the luminance and the contrast ratio can be improved.

FIG. 7A is a plan view for explaining an optical sheet according to a second embodiment of the present invention, and FIG. 7B is a cross-sectional view showing a section taken along line B-B of FIG. 7A.

7A and 7B, an optical sheet 200 according to a second embodiment of the present invention includes a base member 110; A plurality of lens patterns 120 formed on the base member 110; And a plurality of prism patterns 130 formed on the remaining regions of the base member 110 where the plurality of lens patterns 120 are not formed. The optical sheet 200 according to the second embodiment of the present invention has the same configuration as that of the optical sheet 100 of the first embodiment except for a plurality of prism patterns 130 formed on the base member 110 The description of the same configuration will be replaced with the above description.

A plurality of prism patterns 130 are formed in a striped shape in the remaining region of the base member 110 where the plurality of lens patterns 120 are not formed so as to be parallel to the second direction (e.g., . Since the plurality of prism patterns 130 are the same as the optical sheet 100 of the first embodiment described above except that the prism patterns 130 are formed in the second direction of the base member 110, Instead.

In the optical sheet 100 according to the second embodiment of the present invention, a plurality of prism patterns 130 are formed in the remaining region of the base member 110 where the plurality of lens patterns 120 are not formed, And the brightness and the contrast ratio can be improved.

8 is a plan view for explaining an optical sheet according to a third embodiment of the present invention.

Referring to FIG. 8 with reference to FIGS. 4A and 7B, the optical sheet 300 according to the third embodiment of the present invention includes a base member 110; A plurality of lens patterns 120 formed on the base member 110; A plurality of first prism patterns 130a formed in remaining regions of the base member 110 in which the plurality of lens patterns 120 are not formed so as to be parallel to the first direction (e.g., the long side direction) of the base member 110; And a plurality of second prism patterns 130b formed on the remaining region of the base member 110 on which the plurality of lens patterns 120 are not formed so as to be parallel to the second direction (for example, the short side direction) . The optical sheet 300 according to the third embodiment of the present invention has the same structure as the optical sheet 100 of the first embodiment except for the first and second plural prism patterns 130a and 130b The description of the same configuration will be replaced with the above description.

A plurality of first prism patterns 130a are formed on the remaining region of the base member 110 in which the plurality of lens patterns 120 are not formed so that the first prism patterns 130a are aligned with the first direction of the base member 110 . Since the plurality of first prism patterns 130a are the same as those of the optical sheet 100 of the first embodiment, a detailed description thereof will be substituted by the above description.

A plurality of second prism patterns 130b are formed on the remaining region of the base member 110 in which the plurality of lens patterns 120 are not formed so as to be parallel to the second direction of the base member 110 . Since the plurality of second prism patterns 130b are the same as those of the optical sheet 200 of the second embodiment described above, the detailed description thereof is superseded by the above description.

The optical sheet 100 according to the third embodiment of the present invention has the same structure as that of the base member 110 except that the plurality of lens patterns 120 are not formed in the long side and the short side direction of the base member 110, By forming a plurality of prism patterns 130 in the light guide plate 130, the light condensing efficiency and brightness can be further improved, and the contrast ratio can be further improved.

9 is a perspective view for explaining a backlight unit according to an embodiment of the present invention.

Referring to FIG. 9, a backlight unit 400 according to an embodiment of the present invention includes a light source 410; Reflective sheet 420; A diffusion plate 430; A lower diffusion sheet 440; An optical sheet 100; And an upper diffusion sheet 450.

The light source 410 includes a plurality of lamps or a plurality of light emitting diodes disposed at a predetermined interval on the lower surface of the diffusion plate 430. The light source 410 generates light according to the driving of each lamp or the light emitting diode and irradiates the light to the diffusion plate 430.

The reflective sheet 420 is disposed on the lower surface of the light source 410 and reflects light incident from the light source 410 toward the diffusion plate 430 to minimize light loss.

The diffusion plate 430 is disposed on the light source 410 and diffuses the light emitted from the light source 430 to irradiate the lower diffusion sheet 440. At this time, a polymethyl methacrylate material which is made of a transparent material such as polycarbonate, polymethyl methacrylate, or polyethylene terephthalate and has excellent rigidity is mainly used. A diffusion layer (not shown) for diffusing light and a coating layer (not shown) for fixing the diffusion bead may be formed on the lower surface of the diffusion plate 430.

The lower diffusion sheet 440 is disposed on the diffusion plate 430 and diffuses the light emitted from the diffusion plate 430 into the entire area to irradiate the optical sheet 100.

The optical sheet 100 is disposed on the lower diffusion sheet 440 and diffuses and radiates light emitted from the lower diffusion sheet 440 to irradiate the upper diffusion sheet 450. To this end, the optical sheet 100 is composed of the optical sheet according to the first embodiment of the present invention shown in Figs. 3A to 6. In this case, since the optical sheet 100 is made of the optical sheet according to the first embodiment of the present invention described above, the optical sheet 100 according to the first embodiment of the present invention is described instead .

7A and 7B or the optical sheet 300 according to the third embodiment of the present invention shown in FIG. 8, the optical sheet 100 according to the second embodiment of the present invention shown in FIGS. The optical sheets 200 and 300 according to the second and third embodiments of the present invention will be described instead of the optical sheets 200 and 300 described above.

The upper diffusion sheet 450 is disposed on the optical sheet 100 and diffuses the light emitted from the optical sheet 100 into the entire area to irradiate the liquid crystal display panel (not shown).

The backlight unit 400 according to the embodiment of the present invention is configured to include a plurality of lens patterns 120 and an optical sheet 100 having a plurality of prism patterns 130, So that the contrast ratio can be improved.

Further, since the backlight unit 400 uses the inexpensive upper diffusion sheet 450 without using an expensive prism sheet, the production cost can be reduced.

10 is a perspective view illustrating a liquid crystal display device according to an embodiment of the present invention.

Referring to FIG. 10, a liquid crystal display device according to an embodiment of the present invention includes a liquid crystal display panel 500 for displaying an image by adjusting a light transmittance; And a backlight unit 400 for emitting light to the liquid crystal display panel 500. [

The liquid crystal display panel 500 displays a desired image by adjusting the light transmittance of the liquid crystal layer formed between the first and second substrates using the light emitted from the backlight unit 400.

The backlight unit 400 comprises a backlight unit according to the embodiment of the present invention shown in Fig. The backlight unit 400 includes a plurality of lens patterns 120 and an optical sheet 100 having a plurality of prism patterns 130 so that even if an inexpensive upper diffusion sheet 450 is used, The luminance, and the contrast ratio can be improved. Accordingly, the backlight unit 400 uses an inexpensive upper diffusion sheet 450 without using an expensive prism sheet, so that the production cost is lowered.

The liquid crystal display according to the embodiment of the present invention includes the optical sheet 100 having the plurality of lens patterns 120 and the plurality of prism patterns 130 so that the production cost can be reduced. As shown in FIGS. 11A and 11B, the light-condensing efficiency and the luminance can be improved, and the contrast ratio can be improved as shown in FIG. 11C.

11A is a graph showing luminance characteristics when a black image is displayed on the liquid crystal display panel 500 by using the backlight unit 400 including the optical sheets 100, 200, and 300 according to the present invention. (Red region) is decreased to improve the light-condensing efficiency and luminance.

11B is a graph showing luminance characteristics when a white image is displayed on a liquid crystal display panel using a backlight unit 400 including the optical sheets 100, 200, and 300 according to the present invention. And the light collection efficiency and brightness are improved by reducing the area (red area).

11C is a graph showing the contrast ratio characteristics of the liquid crystal display panel 500 driven by the backlight unit 400 including the optical sheets 100, 200 and 300 according to the present invention. Red region) is decreased, thereby improving the contrast ratio.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100: optical sheet 110: base member
120: Lens pattern 130: Prism pattern
400: backlight unit 500: liquid crystal display panel

Claims (10)

A base member;
A plurality of lens patterns provided on an upper surface of the base member; And
A plurality of prisms provided between lens patterns adjacent to each other with reference to a first longitudinal direction of the base member and between lens patterns adjacent to each other with reference to a second longitudinal direction of the base member intersecting with the first longitudinal direction, Pattern,
Wherein each of the plurality of lens patterns is spaced apart from each other along the first longitudinal direction and spaced apart from each other along the second longitudinal direction and is convexly projected from the upper surface of the base member to include a hemispherical surface,
A plurality of prism patterns are provided on the same line between the plurality of lens patterns, and the remaining prism patterns of the plurality of prism patterns extend in a line between the plurality of lens patterns on the same line And,
Wherein the height of the plurality of prism patterns is lower than that of each of the plurality of lens patterns with respect to the upper surface of the base member. delete The method according to claim 1,
Wherein the plurality of prism patterns are arranged to be parallel to at least one of a first longitudinal direction and a second longitudinal direction of the base member. The method of claim 3,
Wherein each of the plurality of prism patterns has any one of an equilateral triangle, an equilateral triangle having a vertex of a curved surface shape, an isosceles triangle, an isosceles triangle having a vertex of a curved surface shape, and an isosceles triangle having a curved surface inclined surface. The method according to claim 1,
And a plurality of reflection patterns provided on a lower surface of the base member. A base member;
A plurality of lens patterns provided on an upper surface of the base member;
A plurality of prisms provided between lens patterns adjacent to each other with reference to a first longitudinal direction of the base member and between lens patterns adjacent to each other with reference to a second longitudinal direction of the base member intersecting with the first longitudinal direction, pattern; And
And a plurality of reflection patterns provided on a lower surface of the base member,
Wherein the plurality of lens patterns are spaced from each other along the first longitudinal direction and are spaced apart from each other along the second longitudinal direction,
A plurality of prism patterns are provided on the same line between the plurality of lens patterns, and the remaining prism patterns of the plurality of prism patterns extend in a line between the plurality of lens patterns on the same line And,
And each of the plurality of reflection patterns overlaps a boundary portion between the lens pattern and the prism pattern. A light source for generating light;
A diffusion plate for diffusing light emitted from the light source;
The optical sheet according to any one of claims 1 to 6, which is disposed on the diffusing plate and condenses and diffuses light emitted from the diffusing plate. And
And an upper diffusion sheet disposed on the optical sheet for diffusing light emitted from the optical sheet. 8. The method of claim 7,
A reflective sheet disposed at a lower portion of the light source and reflecting the incident light toward the diffusion plate; And
And a lower diffusion sheet disposed between the diffusion plate and the optical sheet and diffusing the light emitted from the diffusion plate to irradiate the light onto the optical sheet. A liquid crystal display panel for displaying an image by adjusting a light transmittance; And
And a backlight unit for emitting light to the liquid crystal display panel,
The backlight unit includes:
A light source for generating light;
A diffusion plate for diffusing light emitted from the light source;
The optical sheet according to any one of claims 1 to 6, which is disposed on the diffusing plate and condenses and diffuses light emitted from the diffusing plate. And
And an upper diffusion sheet disposed on the optical sheet for diffusing light emitted from the optical sheet. 10. The method of claim 9,
The backlight unit includes:
A reflective sheet disposed at a lower portion of the light source and reflecting the incident light toward the diffusion plate; And
And a lower diffusion sheet disposed between the diffusion plate and the optical sheet, for diffusing light emitted from the diffusion plate and irradiating the light to the optical sheet.

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