Striped diffuser, method of manufacturing the same, and liquid crystal display device with adjustable viewing angle employing the striped diffuser

• US 8,913,216 B2
• Filed: 02/12/2009
• Issued: 12/16/2014
• Est. Priority Date: 06/16/2008
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Hwang, Seongmo, Lee, Moongyu, Choe, Kyumin
• Primary Examiner(s): Nguyen, Hoan C
• Application Number:
  US12/370,174
• Publication Number:
  US 20090310064A1
• Time in Patent Office: 2,133 Days
• Field of Search: 349/113, 349/96, 349/117, 349/119, 359/599, 359/489.07, 359/485.03, 359/385.05, 362/558
• US Class Current: 349/96
• CPC Class Codes: G02B 2207/123 Optical louvre elements, e.g. for directional light blocking
• CPC Class Codes: G02B 5/0242 by means of dispersed particles
• CPC Class Codes: G02B 5/0263 with positional variation of the diffusing properties, e.g. gradient or patterned diffuser
• CPC Class Codes: G02B 5/0268 characterized by the fabrication or manufacturing method
• CPC Class Codes: G02B 5/0278 used in transmission
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133562 on the viewer side
• CPC Class Codes: G02F 1/133567 on the back side

Abstract

Provided are diffuser, method of manufacturing same, and liquid crystal display device employing the diffuser. Liquid crystal display device includes: backlight unit; liquid crystal panel on which image is formed by using light emitted by backlight unit, and comprising: color filter comprising plurality of pixels each of which comprises plurality of subpixels that are alternately arranged and transmit light in different wavelength bands; and liquid crystal layer whose transmittance is adjusted under electrical control; and diffuser disposed on a top surface or a bottom surface of the liquid crystal panel and comprising diffusing areas and transparent areas which alternate with each other at intervals corresponding to the width of the subpixels, wherein the liquid crystal layer comprises liquid crystal areas corresponding to the diffusing areas and liquid crystal areas corresponding to the transparent areas and the transmittances of the liquid crystal areas are adjusted according to the subpixels.

Claims

1. A liquid crystal display device comprising:

a backlight unit; and

a liquid crystal panel which forms an image using light emitted by the backlight unit, and comprising;

a color filter comprising a plurality of pixels each of which comprises a plurality of subpixels that transmit light in different wavelength bands;

a liquid crystal layer whose transmittance is adjusted under an electrical control;

a first polarizing plate and a second polarizing plate which are spaced apart from each other and the liquid crystal layer is disposed therebetween;

a diffuser disposed directly on the first polarizing plate or the second polarizing plate, the diffuser comprising diffusing areas and transparent areas which alternate with each other at intervals corresponding to the width of each of the subpixels; and

a thin film transistor layer which controls a transmittance of the liquid crystal layer;

wherein an area of the liquid crystal layer corresponding to each of the subpixels is divided into a first liquid crystal area facing one of the diffusing areas and a second liquid crystal area facing one of the transparent areas and transmittances of the first and second liquid crystal areas are adjusted separately, and

wherein the thin film transistor layer includes a first transistor for controlling a transmittance of the first liquid crystal area and a second transistor for controlling a transmittance of the second liquid crystal area.

2. The liquid crystal display device of claim 1, wherein, in a public mode, an image with a wide viewing angle is formed by using light passing through the first liquid crystal area of the liquid crystal layer, and, in a private mode, an image with a narrow viewing angle is formed by not using light passing through the first liquid crystal area of the liquid crystal layer.

3. The liquid crystal display device of claim 2, wherein, in the public mode, light passing through the second liquid crystal area of the liquid crystal layer is not used to form the image with the wide viewing angle.

4. The liquid crystal display device of claim 2, wherein, in the public mode, both the light passing through the first liquid crystal area of the liquid crystal layer and the light passing through the second liquid crystal area of the liquid crystal layer are used to form an image.

5. The liquid crystal display device of claim 1, wherein the diffuser comprises diffusion parts formed of a transparent resin including a plurality of diffusing particles and arranged to be spaced apart from one another.

6. The liquid crystal display device of claim 1, wherein the liquid crystal layer is disposed between an upper transparent substrate and a lower transparent substrate,

wherein, the diffuser is formed on the top surface of the liquid crystal panel and the upper transparent substrate includes a thickness less than five times the width of each of the subpixels.

7. The liquid crystal display device of claim 1, wherein the backlight unit provides collimated light to the liquid crystal panel so that the full width at half maximum of luminance is in a range of ±

20°

.

8. The liquid crystal display device of claim 7, wherein the backlight unit comprises:

a light source;

a light guide plate which guides light emitted by the light source to the liquid crystal panel and comprises a prism formed on at least one of a top surface of the light guide plate and a bottom surface of the light guide plate; and

a reverse prism sheet disposed above the light guide plate.

9. The liquid crystal display device of claim 8, wherein prisms are arranged on the top surface and the bottom surface of the liquid guide plate in directions orthogonal to each other.

10. The liquid crystal display device of claim 7, wherein the backlight unit comprises:

a light source disposed in a reflector and comprising a reflective surface; and

a collimator comprising a plate-shaped member having a plurality of light transmitting areas through which light passes and a plurality of non-transmitting areas formed between the light transmitting areas,

wherein each of the light transmitting areas comprises at least one reflective surface inclined with respect to a plane direction of the plate-shaped member and a direction perpendicular to the plane direction.

11. The liquid crystal display device of claim 10, further comprising a diffusion plate disposed between the light source and the collimator.