Spread illuminating apparatus to illuminate two liquid crystal display panels different in screen size

• US 20040145688A1
• Filed: 12/04/2003
• Published: 07/29/2004
• Est. Priority Date: 01/24/2003
• Status: Active Grant

• Current Assignee: Minebea Company Limited (MinebeaMitsumi Inc.)
• Original Assignee: Minebea Company Limited (MinebeaMitsumi Inc.)
• Inventors: Kawashima, Satoshi, Mizutani, Hitoshi, Egawa, Motoji, Ishigami, Katsuji, Takayanagi, Kazutoshi
• Granted Patent: US 7,248,308 B2
• Time in Patent Office: Days
• US Class Current: 349/113
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0056 for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
• CPC Class Codes: G02B 6/0063 for extracting light out both the major surfaces of the light guide
• CPC Class Codes: G02F 1/133342 for double-sided displays

Abstract

A spread illuminating apparatus includes: at least one light source; a light conductive plate which has the at least one light source disposed at one end surface thereof, and which allows light emitted from the at least one light source and introduced therein to exit out therefrom through both major surfaces thereof toward first and second liquid crystal display elements disposed respectively over the both major surfaces of the light conductive plate, wherein the second liquid crystal display element has a smaller display screen size than the first liquid crystal display element; and a reflecting means which is disposed at the other major surface of the light conductive plate so as to cover at least areas not covered by the second liquid crystal display element, and which reflects light toward the first liquid crystal display element.

Claims

1. A spread illuminating apparatus for illuminating two objects, the apparatus comprising:

at least one light source;

a light conductive plate having the at least one light source provided at one end surface thereof and adapted to allow light emitted from the at least one light source and introduced therein to exit out therefrom through two major surfaces thereof respectively toward a first liquid crystal display element which constitutes one of two objects to be illuminated, and which is disposed over one of the two major surfaces of the light conductive plate, and toward a second liquid crystal element which constitutes the other of the two objects to be illuminated, has a smaller display screen size than the first liquid crystal display element, and which is disposed over the other of the two major surfaces of the light conductive plate; and

a reflecting means disposed at the other major surface of the light conductive plate having the second liquid crystal display element so as to cover at least areas not covered by the second liquid crystal display element, the reflecting means being adapted to reflect light toward the first liquid crystal display element.

2. A spread illuminating apparatus according to claim 1, wherein the reflecting means is a reflector plate provided to cover the areas not covered by the second liquid crystal display element.

3. A spread illuminating apparatus according to claim 1, wherein the reflecting means is a reflective polarizer plate which reflects P-polarized light and transmits S-polarized light selectively, or vice versa.

4. A spread illuminating apparatus according to claim 3, wherein the reflective polarizer plate has a same polarization plane as a polarizing means provided at a surface of the second liquid crystal display element facing the light conductive plate, the reflective polarizer plate substituting for the polarizing means.

5. A spread illuminating apparatus according to claim 1, wherein the reflecting means consists of:

a reflector plate provided to cover the areas not covered by the second liquid crystal display element; and

a reflective polarizer plate which reflects P-polarized light and transmits S-polarized light selectively, or vice versa, and which is provided so as to cover entirely the other major surface of the light conductive plate having the second liquid crystal display element.

6. A spread illuminating apparatus according to claims 2 or 5, wherein the reflector plate has its reflectance matched with reflectance of the second liquid crystal display panel.

7. A spread illuminating apparatus according to claims 2, 5 or 6, wherein the reflecting means has its reflectance gradually varying at a given area close to the second liquid crystal display element.

8. A spread illuminating apparatus according to claim 1, wherein the reflecting means is a reflective polarizer plate which reflects P-polarized light and transmits S-polarized light selectively, or vice versa, and which is provided entirely at and in direct contact with the other major surface of the light conductive plate having the second liquid crystal display element.

9. A spread illuminating apparatus according to claim 1, wherein the reflecting means consists of:

a reflector plate provided so as to cover the areas not covered by the second liquid crystal display element, and a reflective polarizer plate which reflects P-polarized light and transmits S-polarized light selectively, or vice versa, and which is provided entirely at and in direct contact with the other major surface of the light conductive plate having the second liquid crystal display element.