Flat lighting device

• US 5,617,251 A
• Filed: 12/22/1995
• Issued: 04/01/1997
• Est. Priority Date: 12/26/1994
• Status: Expired due to Term

• Current Assignee: Stanley Electric Company Limited
• Original Assignee: Stanley Electric Company Limited
• Inventors: Hanasaki, Koichi, Konishi, Satoru, Ohta, Kazushige
• Primary Examiner(s): NGUYEN, THONG Q
• Application Number:
  US08/577,387
• Time in Patent Office: 466 Days
• Field of Search: 359/599, 359/70, 359/48-50, 362/24, 362/26-27, 362/31, 362/32, 362/84, 385/36, 385/115
• US Class Current: 359/599
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer

Abstract

An improved flat lighting device is provided. The flat lighting device comprises a light transmission member having a luminous surface formed on the front side thereof, a reflection surface on the rear side of said luminous surface, and an incident surface, and further comprises a light source and a reflecting mirror in the vicinity of the side perpendicular to said luminous surface. The thickness of the light transmission member between the luminous surface and the reflection surface is increased wider than that of the incident surface, the lower end of said incident surface is in contact with the reflection surface, said light source and said reflecting mirror are provided closer to the center of the light transmission member inside the end of the luminous surface, said inclined surface is formed by connecting the upper end of the incident surface and the end of the luminous surface, and said inclined surface is provided with a reflection function. According to the invention, the luminous surface can be more luminous owing to reflection by the inclined surface, and the flat lighting device itself can be formed so that the area is approximately equal to the display area of a liquid crystal display for lighting.

Claims

1. A flat lighting device comprising a light transmission member formed by transparent material having a high refractive index, said light transmission member having a luminous surface formed on a front side thereof so that the area of the luminous surface is approximately equal to that of a display for lighting, a reflection surface on the rear side of said luminous surface, and an incident surface, a light source and a reflecting mirror in the vicinity of the side perpendicular to said luminous surface, said flat lighting device being characterized in that the thickness of said light transmission member between said luminous and reflection surfaces is increased wider than that of said incident surface, said incident surface of which lower end is in contact with the reflection surface is provided closer to the center of the light transmission member so that the light source and reflecting mirror are inside said luminous surface, an inclined surface is formed by connecting the upper end of said incident surface and the end of the luminous surface, and said inclined surface is provided with a reflection function.

2. A flat lighting device according to claim 1, wherein the thickness of said light transmission member is equivalent to 20 to 200% of that of said incident surface.