Reflective liquid crystal display device

• US 6,738,116 B2
• Filed: 10/03/2001
• Issued: 05/18/2004
• Est. Priority Date: 12/01/2000
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Sasagawa, Tomohiro, Yuuki, Akimasa, Tobita, Toshio
• Primary Examiner(s): Flynn, Nathan J.
• Assistant Examiner(s): Sefer, Ahmed N.
• Application Number:
  US09/969,509
• Publication Number:
  US 20020067447A1
• Time in Patent Office: 958 Days
• Field of Search: 349/62, 349/63, 349/65, 349/113
• US Class Current: 349/113
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side
• CPC Class Codes: G02F 1/133616 Front illuminating devices

Abstract

A reflective liquid crystal display device having a structure providing high contrast even if there is undesired light. The structure includes a light-guiding plate for receiving, from a light-incident surface, light coming from a light source, and for allowing the light to exit from a bottom surface; a reflective liquid crystal display panel opposed to the bottom surface of the light-guiding plate; and a prism disposed on the side of a top surface of an upper substrate of the liquid crystal display panel. The prism has a surface that is substantially perpendicular to the top surface of the upper substrate, and a tilted surface which is tilted towards a side opposite to the light source from a crest line of the substantially perpendicular surface at a tilt angle with respect to an imaginary surface which passes through the crest line and which is parallel to the top surface of the upper substrate.

Claims

1. A reflective liquid crystal display device comprising:

a light source;

a light-guiding plate, in which light from the light source is received at a side surface of the light-guiding plate, and in which the light exits from a bottom surface of the light-guiding plate;

a reflective liquid crystal display panel disposed parallel to and opposing the bottom surface of the light-guiding plate, the reflective liquid crystal display panel having an upper substrate, a lower substrate, and a liquid crystal layer sandwiched between the upper substrate and the lower substrate; and

a deflecting device for deflecting light which has exited from the bottom surface of the light-guiding plate, and located at a top surface side of the upper substrate of the reflective liquid crystal display panel, wherein the deflecting device includes at least one surface at a light source side substantially perpendicular to the top surface of the upper substrate of the reflective liquid crystal display panel, and at least one tilted surface that tilts towards a side opposite the light source, from a crest line of the at least one substantially perpendicular surface at an angle, with respect to an imaginary surface which passes through the crest line and which is parallel to the top surface of the upper substrate.

2. The reflective liquid crystal display device according to claim 1, wherein tilt angle of the tilted surface of the deflecting device is substantially equal to an exiting angle, with respect to a direction perpendicular to the bottom surface, and the light exiting from the bottom surface of the light-guiding plate at the exiting angle has a peak brightness.

3. The reflective liquid crystal display device according to claim 1, wherein the deflecting device is coated with anti-reflection layer.

4. The reflective liquid crystal display device according to claim 1, wherein the deflecting device includes a plurality of the surfaces at a light-source side, substantially perpendicular to the top surface of the upper substrate of the reflective liquid crystal display panel, and a plurality of the tilted surfaces that tilt towards a side opposite to the light source from crest lines of the corresponding substantially perpendicular surfaces at an angle with respect to the imaginary surface which passes through the crest lines of the corresponding substantially perpendicular surfaces and which is parallel to the top surface of the upper substrate.

5. The reflective liquid crystal display device according to claim 4, wherein tilt angles of the tilted surfaces of the deflecting device are substantially equal to an exiting angle, with respect to a direction perpendicular to the bottom surface, and the light exiting from the bottom surface of the light-guiding plate at the exiting angle has a peak brightness.

6. reflective liquid crystal display device according to claim 4, wherein the tilt angles of the tilted surfaces of the deflecting device are in a range of from 3 degrees to 45 degrees.

7. The reflective liquid crystal display device according to claim 4, wherein the deflecting device comprises an array of prisms separated by gaps and the gaps are narrower than gaps between pixels of the reflective liquid crystal display panel.

8. The reflective liquid crystal display device according to claim 4, wherein the deflecting device is coated with an anti-reflection layer.

9. A reflective liquid crystal display device comprising:

a reflective liquid crystal display panel having an upper substrate, a lower substrate, and a liquid crystal layer sandwiched between the upper substrate and the lower substrate; and

a deflecting device for deflecting light incident from a top surface side of the upper substrate, and located at the top surface side of the upper substrate of the reflective liquid crystal display panel, wherein the deflecting device includes at least one surface at a light source side substantially perpendicular to the top surface of the upper substrate of the reflective liquid crystal display panel, and at least one tilted surface that tilts towards a side opposite a light source, from a crest line of the at least one substantially perpendicular surface at an angle, with respect to an imaginary surface which passes through the crest line and which is parallel to the top surface of the upper substrate.

10. The reflective liquid crystal display device according to claim 9, wherein tilt angle of the tilted surface of the deflecting device is substantially equal to an exiting angle, with respect to a direction perpendicular to the bottom surface, and the light exiting from the bottom surface of the light-guiding plate at the exiting angle has a peak brightness.

11. The reflective liquid crystal display device according to claim 9, wherein the deflecting device is coated with an anti-reflection layer.

12. The reflective liquid crystal display device according to claim 9, wherein the deflecting device includes a plurality of the surfaces at a light-source side, substantially perpendicular to the top surface of the upper substrate of the reflective liquid crystal display panel, and a plurality of the tilted surfaces that tilt towards a side opposite to the light source from crest lines of the corresponding substantially perpendicular surfaces at an angle with respect to the imaginary surface which passes through the crest lines of the corresponding substantially perpendicular surfaces and which is parallel to the top surface of the upper substrate.

13. The reflective liquid crystal display device according to claim 12, wherein tilt angles of the tilted surfaces of the deflecting device are substantially equal to an exiting angle, with respect to a direction perpendicular to the bottom surface, and the light exiting from the bottom surface of the light-guiding plate at the exiting angle has a peak brightness.

14. The reflective liquid crystal display device according to claim 12, wherein the tilt angles of the tilted surfaces of the deflecting device are in a range of from 3 degrees to 45 degrees.

15. The reflective liquid crystal display device according to claim 12, wherein the deflecting device comprises an array of prisms separated by gaps and the gaps are narrower than gaps between pixels of the reflective liquid crystal display panel.

16. The reflective liquid crystal display device according to claim 9, wherein the deflecting device is coated with an anti-reflection layer.