Backlight and frontlight, and liquid crystal display device

• US 20030160911A1
• Filed: 02/26/2003
• Published: 08/28/2003
• Est. Priority Date: 02/27/2002
• Status: Active Grant

• Current Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Original Assignee: ALPS Electric Company Limited (Alps Alpine Co., Ltd.)
• Inventors: Kano, Mitsuru
• Granted Patent: US 7,206,040 B2
• Time in Patent Office: Days
• US Class Current: 349/65
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide

Abstract

The invention relates to a backlight that is disposed on a rear surface side of a subject to be irradiated and illuminates the subject to be irradiated from the rear surface side, and the backlight includes: a light guide plate; an intermediate light guide disposed along an end surface on one side of the light guide plate; and a light source disposed to an end portion of the intermediate light guide; wherein one surface side of the light guide plate is formed into a reflection surface on which a concavoconvex shape is formed so as to reflect light propagating inside thereof; the other surface side of the light guide plate is formed into an exit surface that outputs the light reflected by the reflection surface; on the reflection surface, a plurality of grooves that are formed of a gentle slope portion and a steep slope portion is continuously formed in stripe; and outside of the exit surface, the subject to be irradiated is disposed.

Claims

1. A backlight that is disposed on a rear surface side of a subject to be irradiated and illuminates the subject to be irradiated from the rear surface side, comprising:

a light guide plate;

an intermediate light guide disposed along an end surface of one side of the light guide plate; and

a light source disposed to the intermediate light guide;

wherein one surface side of the light guide plate is formed into a reflection surface on which a concavoconvex shape is formed so as to reflect light propagating inside thereof;

the other surface side of the light guide plate is formed into an exit surface that outputs the light reflected by the reflection surface;

on the reflection surface, a plurality of grooves that are formed of a gentle slope portion and a steep slope portion that has an angle of inclination steeper than that of the gentle slope portion is continuously formed in stripe; and

outside of the exit surface, the subject to be irradiated is disposed.

2. A backlight as set forth in claim 1:

wherein the light source is formed of a light-emitting diode having any one color of green, bluish green, blue, orange, red and yellowish green color.

3. A backlight as set forth in claim 1:

wherein a cover member that has at least a reflection surface cover portion that covers a side end portion on a reflection surface side of the light guide plate;

a light guide cover portion that covers the intermediate light guide; and

an exit surface cover portion that covers a side end portion on an exit surface side of the light guide plate is attached so as to cover at least the intermediate light guide and a side end portion of the light guide plate.

4. A backlight as set forth in claim 3:

wherein the cover member is made of a metal plate and on an inner surface side thereof a reflection surface is formed.

5. A backlight as set forth in claim 2:

wherein the subject to be irradiated is a black-and-white display type transmissive or semi-transmissive liquid crystal display unit.

6. A liquid crystal display device, comprising:

a backlight that includes a light guide plate;

an intermediate light guide disposed along an end surface on one side of the light guide plate; and

a light source disposed to an end portion of the intermediate light guide;

wherein one surface side of the light guide plate is formed into a reflection surface on which a concavoconvex shape is formed so as to reflect light propagating inside thereof;

the other surface side of the light guide plate is formed into an exit surface that outputs the light reflected by the reflection surface; and

on the reflection surface, a plurality of grooves that are formed of a gentle slope portion and a steep slope portion that has an angle of inclination steeper than that of the gentle slope portion is continuously formed in stripe; and

a transmissive or semi-transmissive liquid crystal display unit disposed outside of the exit surface of the backlight.

7. A liquid crystal display device as set forth in claim 6:

wherein the liquid crystal display unit is a transmissive or semi-transmissive black-and-white display type.

8. A liquid crystal display device as set forth in claim 6:

wherein the light source is formed of a light-emitting diode having any one color of green, bluish green, blue, orange, red and yellowish green color.

9. A liquid crystal display device as set forth in claim 6:

wherein a cover member that has at least a reflection surface cover portion that covers a side end portion on a reflection surface side of the light guide plate;

a light guide cover portion that covers the intermediate light guide; and

an exit surface cover portion that covers a side end portion on an exit surface side of the light guide plate is attached so as to cover at least the intermediate light guide and a side end portion of the light guide plate.

10. A liquid crystal display device as set forth in claim 9:

wherein the cover member is made of a metal plate and on an inner surface thereof a reflection surface is formed.

11. A frontlight that is disposed on a front surface side of a subject to be irradiated and illuminates the subject to be irradiated from the front surface side, comprising:

a light guide plate;

an intermediate light guide disposed along an end surface on one side of the light guide plate; and

a light source disposed to the intermediate light guide;

wherein one surface side of the light guide plate is formed into a reflection surface on which a concavoconvex shape is formed so as to reflect light propagating inside thereof;

the other surface side of the light guide plate is formed into an exit surface that outputs the light reflected by the reflection surface;

on the reflection surface, a plurality of grooves that are formed of a gentle slope portion and a steep slope portion that has an angle of inclination steeper than that of the gentle slope portion is continuously formed in stripe; and

the light source is formed of a light-emitting diode having any one color of green, bluish green, blue, orange, red and yellowish green color.

12. A frontlight as set forth in claim 11:

wherein a cover member that has at least a reflection surface cover portion that covers a side end portion on a reflection surface side of the light guide plate;

a light guide cover portion that covers the intermediate light guide; and

an exit surface cover portion that covers a side end portion on an exit surface side of the light guide plate is attached so as to cover at least the intermediate light guide and a side end portion of the light guide plate.

13. A frontlight as set forth in claim 12:

wherein the cover member is made of a metal plate and on an inner surface side thereof a reflection surface is formed.

14. A frontlight as set forth in claim 11:

wherein the subject to be irradiated is a black-and-white display type reflective liquid crystal display unit.

15. A liquid crystal display device, comprising:

a frontlight that includes a light guide plate;

an intermediate light guide disposed along an end surface on one side of the light guide plate; and

a light source disposed to an end portion of the intermediate light guide;

wherein one surface side of the light guide plate is formed into a reflection surface on which a concavoconvex shape is formed so as to reflect light propagating inside thereof;

the other surface side of the light guide plate is formed into an exit surface that outputs the light reflected by the reflection surface;

on the reflection surface, a plurality of grooves that are formed of a gentle slope portion and a steep slope portion that has an angle of inclination steeper than that of the gentle slope portion is continuously formed in stripe; and

the light source is formed of a light-emitting diode having any one color of green, bluish green, blue, orange, red and yellowish green color; and

a liquid crystal display unit disposed outside of the exit surface of the frontlight.

16. A liquid crystal display device as set forth in claim 15:

wherein the liquid crystal display unit is a reflective black-and-white display type.

17. A liquid crystal display device as set forth in claim 15:

wherein a cover member that has at least a reflection surface cover portion that covers a side end portion on a reflection surface side of the light guide plate;

a light guide cover portion that covers the intermediate light guide; and

an exit surface cover portion that covers a side end portion on an exit surface side of the light guide plate is attached so as to cover at least the intermediate light guide and a side end portion of the light guide plate.

18. A liquid crystal display device as set forth in claim 15:

wherein the cover member is made of a metal plate and on an inner surface thereof a reflection surface is formed.