Flat light source

• US 7,543,970 B2
• Filed: 06/07/2007
• Issued: 06/09/2009
• Est. Priority Date: 06/09/2006
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Kiyohara, Toru, Yoneda, Toshiyuki
• Primary Examiner(s): Sawhney; Hargobind S
• Application Number:
  US11/759,637
• Publication Number:
  US 20070285944A1
• Time in Patent Office: 733 Days
• Field of Search: 362/26, 362/248, 362/555, 362/561, 362/606, 362/608, 362/609, 362/610, 362/612, 362/613, 362/615, 362/618, 362/633, 362/800, 349/58, 349/59, 349/62, 349/65, 349/69, 257/E33.057, 257/33.072
• US Class Current: 362/612
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0091 of the light source relative to the light guide G02B6/0021 takes precedence

Abstract

Each point light source includes an overhang projecting perpendicularly to a light emitting surface from one side of the light emitting surface, and the overhang has its main surface made in contact with a light outgoing surface of a light guide plate with the light emitting surface facing a light incident surface of the light guide plate. Engagement of the overhang with the light outgoing surface of the light guide plate prevents a displacement of the light emitting surface of the point light source and the light incident surface of the light guide plate even when the light guide plate suffers from deformation such as warpage. Even if a displacement occurs, the presence of the overhang reflects leaked light to guide it to the light incident surface of the light guide plate.

Claims

1. A flat light source comprising:

a flat light guide plate having one main surface serving as a light outgoing surface from which light outgoes and the other main surface serving as a reflection surface opposite to said light outgoing surface; and

a plurality of point light sources respectively separately provided at least on one side surface of said light guide plate,

wherein

said one side surface of said light guide plate on which said plurality of point light sources are provided serves as a light incident surface,

each of said plurality of point light sources includes a block-like body with a light source stored therein, one surface of said body serving as a light emitting surface at which a light emitting part of said light source is exposed, each of said point light sources at least including a first overhang projecting from one side of said light emitting surface perpendicularly to said light emitting surface, and

said first overhang has its main surface made in contact with one of said light outgoing surface and said reflection surface with said plurality of point light sources disposed such that said light emitting surface faces said light incident surface.

2. The flat light source according to claim 1, wherein

each of said plurality of point light sources includes a second overhang projecting from a side paired with said one side of said light emitting surface from which said first overhang projects, said second overhang projecting perpendicularly to said light emitting surface, and

said first overhang has its main surface made in contact with said light outgoing surface and said second overhang has its main surface made in contact with said reflection surface, with said plurality of point light sources disposed such that said light emitting surface faces said light incident surface.

3. The flat light source according to claim 2, wherein

said light outgoing surface of said light guide plate includes a first recess reaching a depth equal to or greater than the thickness of said first overhang at least in a portion with which said main surface of said first overhang is in contact, and

said reflection surface of said light guide plate includes a second recess reaching a depth equal to or greater than the thickness of said second overhang at least in a portion with which said main surface of said second overhang is in contact.