Surface lighting device and a display having such a lighting device
AssigneeCanon Kabushiki Kaisha
InventorsToshiyuki Kanda, Hisao Tajima, Hiroshi Takabayashi, Takashi Yamamoto, Hideo Mori
Life of this patent
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Abstract
A surface lighting device receiving incident rays through two opposing faces of a light guide from light source to emit the incident rays from a face different from the two faces. The light guide is divided into plural divisions which are jointed together.
Claims12
A surface lighting device provided with a light source and a reflection board to reflect rays of light emitted from the light source forward, wherein
- the color of said reflection board is set against a standard color within a range of -2.0 to 0 at .DELTA.b* value in CIE1976L*a*b*, wherein
- L* denotes psychometric lightness,
- a* denotes psychometric perceived chromaticity in the red-green region,
- b* denotes psychometric perceived chromaticity in the blue-yellow region of CIE1976, a uniform color space defined using a three-dimensional rectangular coordinate system adopted at the Commission Internationale de l'Eclainage, and
- .DELTA.b* denotes a difference between b* of a reference color and b* of a measured color of said reflection board, wherein a value of .DELTA.b* of the measured color of the reflection board is not smaller by -2 than a reference color, and smaller by 0 than the reference color at an initial state, and when the reflection board is continuously illuminated for 10,000 hours, the .DELTA.b* value of the color of the reflection board is smaller than 2, and
- the reference color is a color directly above the light source.
A display having a surface lighting means provided with a light source having power supply leads, and a reflection board to which said light source is fixed, and a display panel to which rays of light from said means are irradiated, wherein
- the color of said reflection board is set against a standard color within a range of -2.0 to 0 at .DELTA.b* value in CIE1976L*a*b*,
- wherein L* denotes psychometric lightness,
- a* denotes psychometric perceived chromaticity in the red-green region,
- b* denotes psychometric perceived chromaticity in the blue-yellow region of CIE1976, a uniform color space defined using a three-dimensional rectangular coordinate system adopted at the Commission Internationale de l'Eclainage, and
- .DELTA.b* denotes a difference between b* of a reference color and b* of a measured color of said reflection board, wherein a value of .DELTA.b* of the measured color of the reflection board is not smaller by -2 than a reference color, and smaller by 0 than the reference color at an initial state, and when the reflection board is continuously illuminated for 10,000 hours, the .DELTA.b* value of the color of the reflection board is smaller than 2, and
- the reference color is a color directly above the light source.
Dependencies are inferred from the claim text.