KR100610613B1 - Optical Sheet And Back Light Unit Using The Same - Google Patents

Abstract

The present invention relates to an optical sheet and a backlight unit using the same.

An optical sheet according to an embodiment of the present invention comprises a diffusion layer for diffusing light emitted from the outside, a plurality of lenses formed on the diffusion layer; And a medium formed between the adjacent lenses and having different optical properties from the lens.

Description

Optical sheet and back light unit using the same             

1 is a view showing a conventional liquid crystal display device.

FIG. 2 is a cross-sectional view illustrating a cross section taken along the line II-II ′ of FIG. 1.

3 is a diagram illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

4 is a cross-sectional view taken along the line IV-IV ′ of FIG. 3.

FIG. 5A is a detailed view of the optical member shown in FIG. 4.

FIG. 5B is a cross-sectional view taken along the line VV ′ of FIG. 5A.

6A and 6B are luminance distribution diagrams illustrating diffusion and condensing characteristics of an optical member according to an exemplary embodiment of the present disclosure.

7 is a view showing an optical path of the optical member according to an embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

2, 102: liquid crystal display panels 8, 18, 108, 118: polarizing sheet

10 optical sheet 12 diffuser plate

14, 114: reflector 34, 134: case

36, 136: lamp 110: optical member

120: diffusion layer 130: lens

140: medium

The present invention relates to an optical sheet and a backlight unit using the same, and more particularly, to an optical sheet capable of realizing high luminance and a backlight unit using the same.

In general, liquid crystal displays (hereinafter referred to as "LCDs") have tended to be increasingly wider in application due to features such as light weight, thinness, and low power consumption. According to this trend, LCDs are used for office automation equipment, audio / video equipment, and the like. On the other hand, the LCD is controlled to display the desired image on the screen by adjusting the transmission amount of the light beam according to the image signal applied to the plurality of control switches arranged in a matrix form.

Since the LCD is not a self-luminous display device, a light source such as a back light is required. Such LCD backlight has a direct type and an edge type. In the edge type system, a lamp is installed outside the flat plate, and light is incident from the lamp onto the entire surface of the liquid crystal display panel using a transparent light guide plate. The direct type places several lamps on the plane. A diffusion plate is provided between the lamp and the liquid crystal display panel to maintain a constant space between the liquid crystal display panel and the lamp. On the other hand, according to the type of lamp, the cold cathode tube ("CCFL") method of supplying power by inserting electrodes at both ends of the glass tube of the lamp, and the metal tube of both ends of the glass tube of the lamp There is an external electrode fluorescent lamp ("EEFL") that supplies power to the surrounding electrode.

1 and 2 show a conventional LCD.

1 and 2, a conventional LCD includes a liquid crystal display panel 2 for displaying an image and a backlight unit for irradiating uniform light onto the liquid crystal display panel 2.

In the liquid crystal display panel 2, liquid crystal cells are arranged in an active matrix between upper and lower substrates, and pixel electrodes and a common electrode for applying an electric field to each of the liquid crystal cells are provided. Each of these pixel electrodes is connected to a thin film transistor used as a switch element. The pixel electrode drives the liquid crystal cell along with the common electrode according to the data signal supplied through the thin film transistor to display an image corresponding to the video signal.

The backlight unit includes a case 34, a reflecting plate 14 stacked on the front of the case 34, a plurality of lamps 36 positioned on the reflecting plate 14, and a plurality of lamps 36. The diffuser plate 12 and the optical sheet 10 which are arrange | positioned are provided.

The case 34 converts a path of light generated from the lamps 36 by reflecting visible light traveling toward the side and the back of the plurality of lamps 36 toward the front side, that is, the diffuser plate 12.

The reflective plate 14 is disposed between the upper surface of the case 34 and the plurality of lamps 36 to reflect the light generated from the lamps 36 and to be irradiated toward the liquid crystal display panel 2 to improve the light efficiency. .

Each of the plurality of lamps 36 includes a glass tube, inert gases inside the glass tube, and a cathode and an anode portion made of metal covering both ends of the glass tube. These multiple lamps 36 are arranged side by side on the case 34.

The diffusion plate 12 allows the light emitted from the plurality of lamps 36 to propagate to the liquid crystal display panel and to be incident at a wide range of angles.

The optical sheets 10 may improve the front brightness of the liquid crystal display and reduce power consumption by narrowing the viewing angle of the light emitted from the diffuser plate 12.

Conventional liquid crystal display devices having such a structure have a lot of problems in achieving high luminance due to poor light transmittance of the polarizing plates 8 and 18 and the liquid crystal. Accordingly, there is an urgent need for an optical member capable of scattering light generated from the lamps 36 to increase diffusibility, and increase light condensation to improve overall light efficiency.

Accordingly, it is an object of the present invention to provide an optical sheet capable of achieving high luminance and a backlight unit using the same.

In order to achieve the above object, an optical sheet according to an embodiment of the present invention comprises a diffusion layer for diffusing light emitted from the outside, and a plurality of lenses formed on the diffusion layer; And a medium formed between the adjacent lenses and having different optical properties from the lens.

The lens is in contact with the diffusion layer is formed of at least one of a circle, an ellipse, a polygon, the contact surface has a predetermined height and is formed of at least one of a semi-spherical and semi-elliptic sphere.

The lens has a long axis, a short axis, and a height ratio of 2.5 to 3.5: 0.5 to 3.5: 0.1 to 3.0.

The thickness of the medium is formed below the vertex of the lens from the upper surface of the diffusion layer.

The medium is formed of at least one of a metallic reflective material and a polymer liquid resin.

The metallic reflective material is at least one of nickel (Ni), chromium (Cr), aluminum (Al), and aluminum oxide (Al ₂ O ₃ ).

The polymer liquid resin is formed of at least one of acrylic and urethane.

The diffusion layer is formed with a plurality of beads for diffusing light therein.

The diffusion layer and the plurality of lenses are integrated.

The lens is formed with at least one of an array of micro lens arrays, honeycomb lenses, and broken lenticular lenses.

A backlight unit according to an exemplary embodiment of the present invention includes a backlight unit in which a plurality of light sources are installed in a liquid crystal display, comprising: a diffusion layer for diffusing light from the light source; A plurality of lenses formed on the diffusion layer; And a medium formed between the adjacent lenses and having different optical properties from the lens.

Other objects and features of the present invention in addition to the above object will be apparent from the description of the embodiments with reference to the accompanying drawings.

3 and 4 illustrate a liquid crystal display according to an exemplary embodiment of the present invention.

3 and 4, a liquid crystal display according to an exemplary embodiment includes a liquid crystal display panel 102 and a backlight unit for irradiating light onto the liquid crystal display panel 102.

In the liquid crystal display panel 102, liquid crystal cells are arranged in an active matrix form between upper and lower glass substrates, and thin film transistors for switching video signals are provided in each of the liquid crystal cells. It is. The liquid crystal display panel 102 may display an image corresponding to the video signal by changing the refractive index of each of the liquid crystal cells according to the video signal. A tape carrier package (not shown) in which a driver integrated circuit for applying a driving signal to a thin film transistor is mounted on the lower substrate of the liquid crystal display panel 102 is attached. In addition, polarizing sheets 108 and 118 are provided on the front and rear surfaces of the liquid crystal display panel 102, respectively. Here, the polarizing sheets 108 and 118 function to improve the viewing angle of the image displayed by the liquid crystal cells.

The backlight unit receives power from an external power source and includes a plurality of lamps 136 for irradiating light to the liquid crystal display panel 102, a case 134 for storing the plurality of lamps 136, a lamp 136 and A reflection plate 114 installed between the case 134 to prevent leakage of light generated from the lamp 136 and reflecting the light, and an optical member 110 for diffusing and condensing the light generated from the lamp 136. It is provided.

Each of the lamps 136 includes a glass tube, inert gases inside the glass tube, and a cathode and an anode installed at both ends of the glass tube. Inert gas is filled in the glass tube, and phosphor is coated on the inner wall of the glass tube. Each of the plurality of lamps 136, when the AC voltage from the inverter is applied to the high voltage electrode and the low pressure electrode, electrons are emitted from the low pressure electrode collides with the inert gas inside the glass tube to increase the amount of electrons exponentially. . Thereafter, electric current flows inside the glass tube by the increased electrons, and ultraviolet rays are emitted as the inert gas is excited by the electrons. Ultraviolet rays emitted in this manner collide with the luminescent phosphor applied to the inner wall of the glass tube to emit visible light.

The case 134 housing the plurality of lamps 136 is generated in the lamps 136 by reflecting visible light traveling toward the side and the back of the plurality of lamps 136 toward the front, that is, the optical member 110. The path of the light to be converted. In this case 134, a plurality of lamps 136 are arranged at regular intervals.

The reflective plate 114 is disposed between the upper surface of the case 134 and the plurality of lamps 136 to convert a path of light irradiated in the opposite direction of the liquid crystal display panel 102 among the light generated from the lamps 136. Irradiation toward the display panel 102 improves the efficiency of light.

The optical member 110 diffuses the light emitted from the lamps 136 and changes the path of the light so that the light incident on the liquid crystal display panel 102 can be directly directed to the liquid crystal display panel 102. The front luminance of the display panel 102 is improved. This optical member 110 will be described in detail with reference to FIG. 5.

Referring to FIG. 5, an optical member 110 according to an exemplary embodiment of the present invention includes a diffusion layer 120, a plurality of lenses 130 formed on the diffusion layer 120, and each of the lenses 130. It has a medium 140 formed in the contact area in contact.

The diffusion layer 120 allows the light emitted from the plurality of lamps 136 to propagate to the liquid crystal display panel 102 and can be incident at a wide range of angles. The diffusion layer 120 has a plurality of beads (beads) formed therein to diffuse the light generated from the lamps 136, thereby extending the emission range of the light emitted from the surface of the diffusion layer 120. The diffusion layer 120 is formed of at least one of optical resins such as polymethylmethacrylate (PMMA), polycarbonate, and methyl methacrylate-styrene copolymer (MS resin).

The lens 130 is formed in any one of a circular, elliptical and polygonal shape of the contact surface on the diffusion layer 120, and extends at least one of a semi-spherical and semi-elliptic sphere with a predetermined height. The plurality of lenses 130 are formed in a uniform arrangement on the diffusion layer 120. Here, the back of the lens 130 is formed in any one of a circular, oval, polygonal shape, in particular, having a hexagonal shape occupies the entire surface of the diffusion layer 120 without empty space. When the lens 130 has an elliptical cross section, an eccentricity of the elliptical cross section contacting the diffusion layer 120 is formed within 0 to 0.94 in order to maximize the light converging effect. The uniaxial and height ratio is 2.5 to 3.5: 0.5 to 3.5: 0.1 to 3.0 is preferably formed in a ratio of 3: 1: 0.3. In addition, the plurality of lenses 130 are formed of a micro lens array (MLA), a honeycomb lens, a broken lenticular lens array, or the like, and are formed of the same material as that of the diffusion layer 120 to form a diffusion layer. It may be integrated with 120. Here, each ratio follows the optimal ratio according to the experimental results.

The medium 140 fills the valleys formed between the lenses 130 in a contact area between the plurality of lenses 130 formed on the front surface of the diffusion layer 120, and has a refractive index different from that of the lens 130 and from the diffusion layer 120. It is formed below the height of the apex of 130. The material of the medium 140 may have a refractive index such as metallic reflective materials such as nickel (Ni), chromium (Cr), aluminum (Al), aluminum oxide (Al ₂ O ₃ ), and polymer liquid resins such as acrylic and urethane. It is formed of at least one of other permeable materials.

Optical member 110 according to an embodiment of the present invention having such a structure is formed on the rear surface of the lens 130 in any one of the shape of a circle, oval and polygon, while the upper shape of the spherical and elliptic sphere of a predetermined height Due to the formation of at least one, the edge region of the lens 130 in contact with the front surface of the diffusion layer 120 is thinner than the central region of the lens 130. Accordingly, the light passing through the diffusion layer 120 and passing through the edge region of the lens 130 has a different light diffusing and condensing characteristic compared to the central region of the lens 130, as shown in FIG. 6A. Shows the same diffusion and condensing properties. On the other hand, by forming a medium 140 having a different refractive index from the lens 130 in the areas where the rear surfaces of the lenses 130 are in contact with each other, the optical characteristics in the contact areas of the lenses 130 are improved, which is illustrated in FIG. 6B. As described above, diffusion and light collection characteristics are improved.

An optical path of the optical member 110 having such a medium 140 is shown in FIG. 7. Referring to FIG. 7, the optical member 110 according to the exemplary embodiment of the present invention diffuses and condenses the light generated from the lamp 136 using the medium 140, and then irradiates the light toward the liquid crystal display panel 102. To be. Accordingly, the optical member 110 according to the embodiment of the present invention can improve the brightness of the liquid crystal display panel 102 by optimizing the diffusion and condensation of light generated from the lamp 136.

As described above, the optical sheet and the backlight unit using the optical sheet according to the embodiment of the present invention can dramatically improve the efficiency of the light irradiated from the lamp to achieve high brightness of the liquid crystal display device.                     

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.

Claims (11)

A diffusion layer for diffusing light radiated from the outside; A plurality of lenses formed on the diffusion layer; And a medium formed between the adjacent lenses and having a medium different in optical properties from the lens. The method of claim 1, The lens And a surface in contact with the diffusion layer is formed of at least one of a circle, an ellipse, and a polygon, and has a predetermined height at the contact surface and is formed of at least one of a semi-spherical shape and a semi-elliptic sphere. The method of claim 1, The lens An optical sheet comprising a long axis, a short axis, and a height ratio of 2.5 to 3.5: 0.5 to 3.5: 0.1 to 3.0. The method of claim 1, The thickness of the medium And an optical sheet formed below the vertex of the lens from an upper surface of the diffusion layer. The method of claim 1, The medium is At least one of a metallic reflective material and a polymer liquid resin. The method of claim 5, The metallic reflective material is at least one of nickel (Ni), chromium (Cr), aluminum (Al), aluminum oxide (Al ₂ O ₃ ). The method of claim 5, The polymer liquid resin is an optical sheet, characterized in that formed with at least one of acrylic, urethane. The method of claim 1, The diffusion layer is An optical sheet, characterized in that a plurality of beads are formed therein for diffusing light. The method of claim 1, And the diffusion layer and the plurality of lenses are integrated. The method of claim 1, The lens And at least one of an array of micro lens arrays, honeycomb lenses, and broken lenticular lenses. In the backlight unit in which a plurality of light sources are installed in the liquid crystal display device, A diffusion layer for diffusing light from the light source; A plurality of lenses formed on the diffusion layer; And a medium formed between the adjacent lenses and having a different light characteristic from the lens.

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