Liquid crystal display using a plurality of light adjusting sheets angled at 5 degrees or more

• US 5,394,255 A
• Filed: 01/26/1993
• Issued: 02/28/1995
• Est. Priority Date: 01/27/1992
• Status: Expired due to Term

• Current Assignee: Sekisui Kagaku Kogyo Kabushiki Kaisha
• Original Assignee: Sekisui Kagaku Kogyo Kabushiki Kaisha
• Inventors: Yokota, Tomohiro, Fujigami, Makoto, Ogawara, Hiroshi, Nishitani, Fumio, Kubo, Akihito
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US08/008,995
• Time in Patent Office: 763 Days
• Field of Search: 359/48, 359/49, 359/50, 359/42, 359/69, 362/26, 362/31, 362/32, 362/27, 362/331, 362/335
• US Class Current: 349/64
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer

Abstract

A light adjusting sheet for a planar lighting device includes a plurality of convex and concave streaks arranged alternately and approximately parallel to each other on one surface. The streaks may have a cross section of a sine curve. Another light adjusting sheet consists of a plurality of single sheets each having the above configulation, stacked together. A planar lighting device includes the light adjusting sheet of the above configulation, wherein peak lines of the convex streaks and bottom lines of the concave streaks are arranged to make a predetermined angle with an axis of a linear light source. The liquid crystal display includes a liquid crystal display element placed on front of the planar lighting device of the above configulation.

Claims

1. A planar lighting device comprising:

a light adjusting sheet having a plurality of convex regions and concave regions on one surface;

each convex region and concave region being arranged alternately and approximately parallel to each other;

a light guiding plate having a dot pattern on a back surface being placed in back of said light adjusting sheet;

a linear light source placed on at least one side of said light guiding plate;

a reflector plate being placed in back of said light guiding plate;

wherein peak lines of said convex region and bottom lines of said concave regions of said light adjusting sheet are arranged to make a predetermined angle with an axis of said linear light source;

each of said convex regions having a cross section of a convex arc and each of said concave regions having a cross section of a concave arc; and

wherein said light adjusting sheet comprises a plurality of single sheets each having a plurality of convex regions and concave regions arranged alternately and approximately parallel to each other, stacked together in such a way that peak lines of said convex regions and bottom lines of said concave regions of one single sheet make an angle of 5°

or greater with peak lines of said convex regions and bottom lines of said concave regions of at least one other single sheet.

2. A planar lighting device, according to claim 1:

wherein peak lines of said convex regions and bottom lines of said concave regions make an angle in the range of 5°

to 85°

either in the clockwise direction or in the counterclockwise direction with an axis of said linear light source.

3. A planar lighting device, according to claim 1:

wherein at least two of said single sheets are stacked so that said peak lines and said bottom lines of one single sheet makes an angle of 5°

or greater with said peak lines and said bottom lines of the other single sheet;

said peak lines and said bottom lines of said one single sheet makes an angle in the range of 5°

to 85°

in the clockwise direction with an axis of said linear light source; and

said peak lines and said bottom lines of said the other single sheet makes an angle in the range of 5°

to 85°

in the counterclockwise direction with an axis of said linear light source.

4. A liquid crystal display comprising:

a light adjusting sheet having a plurality of convex regions and concave regions on one surface, each of said convex regions having a cross section of a convex arc and each of said concave regions having a cross section of a concave arc, each convex region and each concave region being arranged alternately and approximately parallel to each other;

a light guiding plate having a dot pattern on a back surface placed in back of said light adjusting sheet;

a linear light source placed on at least one side of said light guiding plate;

a reflector plate being placed in back of said light guiding plate;

a liquid crystal display element being forward of said light guiding plate;

wherein peak lines of said convex regions and bottom lines of said concave regions of said light adjusting sheet being arranged to make a predetermined angle with an axis of said linear light source;

said light adjusting sheet comprising a plurality of single sheets each having a plurality of convex regions and concave regions arranged alternately and approximately parallel to each other on one surface, stacked together in such a way that peak lines of said convex regions and bottom lines of said concave regions of one single sheet make an angle of 5°

or greater with peak lines of said convex regions and bottom lines of said concave regions of at least one other single sheet.

5. A liquid crystal display, according to claim 4:

wherein peak lines of said convex regions and bottom lines of said concave regions make an angle in the range of 5°

to 85°

either in the clockwise direction or in the counterclockwise direction with an axis of said linear light source.

6. A liquid crystal display, according to claim 4:

wherein at least two of said single sheets are stacked so that said peak lines and said bottoms lines of one single sheet makes an angle of 5°

or greater with said peak lines and said bottom lines of the other single sheet;

said peak lines and said bottom lines of said one single sheet make an angle in the range of 5°

to 85°

in the clockwise direction with an axis of said linear light source; and

said peak lines and said bottom lines of said the other single sheet make an angle in the range of 5°

to 85°

in the counterclockwise direction with an axis of said linear light source.

7. A planar lighting device comprising:

a light adjusting sheet having a plurality of convex regions and concave regions on one surface, each convex region and each concave region being arranged alternately and approximately parallel to each other;

a light guiding plate having a dot pattern on a back surface being placed back of said light adjusting sheet;

a linear light source placed on at least one side of said light guiding plate; and

a reflector plate being placed back of said light guiding plate;

wherein peak lines of said convex regions and bottom lines of said concave regions of said light adjusting sheet being arranged to make a predetermined angle with an axis of said linear light source;

wherein said light adjusting sheet comprises a plurality of single sheets each having a plurality of convex regions and concave regions arranged alternately and approximately parallel to each other, stacked together in such a way that peak lines of said convex regions and bottom lines of said concave regions of one single sheet make an angle of 5°

or greater with peak lines of said convex regions and bottom lines of said concave regions of at least one other single sheet.

8. A planar lighting device, according to claim 7, wherein at least two of said single sheets are stacked so that said peak lines and said bottom lines of one single sheet makes an angle of 5°

degrees or greater with said peak lines and said bottom lines of the other single sheet;

said peak lines and said bottom lines of said one single sheet makes an angle in the range of 5°

to 85°

in the clockwise direction with an axis of said linear light source; and

said peak lines and said bottom lines of said other single sheet makes an angle in the range of 5°

to 85°

in the counterclockwise direction with an axis of said linear light source.