Luminaire with improved light utilization efficiency

• US 6,552,760 B1
• Filed: 02/17/2000
• Issued: 04/22/2003
• Est. Priority Date: 02/18/1999
• Status: Expired due to Term

• Current Assignee: Intellectual Ventures I LLC (Intellectual Ventures LLC)
• Original Assignee: Fujitsu Limited
• Inventors: Hayashi, Keiji, Ohashi, Noriyuki, Suzuki, Toshihiro, Hamada, Tetsuya, Kobayashi, Tetsuya, Yamaguchi, Hisashi, Sugawara, Mari, Gotoh, Takeshi
• Primary Examiner(s): Kim, Robert H.
• Assistant Examiner(s): CHUNG, DAVID Y
• Application Number:
  US09/506,267
• Time in Patent Office: 1,160 Days
• Field of Search: 349/56, 349/5, 349/6, 349/7, 349/8, 353/30, 353/31, 353/38, 353/39, 359/641, 359/642, 359/648, 359/649, 359/721, 359/798, 359/799, 359/800
• US Class Current: 349/56
• CPC Class Codes: G02B 27/285 comprising arrays of elements, e.g. microprisms
• CPC Class Codes: H04N 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20

Abstract

A lens array 22C has convex lenses 221 and 221C arranged in alternate and staggering manner to one another. In combination with a condenser lens 23, the convex lenses 221 form images of respective convex lenses 211 of a lens array 21 on a plane 24 to be illuminated in overlapping so that an illuminance distribution on the plane 24 is almost uniform, while the convex lenses 221C whose focal length is longer than that of the convex lenses 211 make on the plane 24 an illuminance distribution of a mountain-shape. Flat plate portions and concave lenses may be employed instead of the convex lenses 221C. A polarization conversion element comprises two elements and an element disposed therebetween with its longitudinal direction being perpendicular to the two element. The images of a light emitting part are included in band-shaped useful incident areas. A polarization conversion section comprises a middle part which is thin but has a larger divergent angle and side parts each has a smaller divergent angle and a simpler construction but is thicker with its size larger.

Claims

1. An illuminance distribution improving device for a luminaire comprising:

a first lens array having a plurality of convex lenses each having a first focal length;

a second lens array, having a plurality of lenses corresponding to respective lenses of said first lens array, disposed opposite to said first lens array; and

a condenser lens disposed on the opposite side to said first lens array with respect to said second lens array,

wherein a distance between said first and second lens arrays is substantially equal to said first focal length,

wherein said second lens array has;

a first lens group composed of a plurality of convex lenses each having a second focal length; and

a second lens group composed of a plurality of lenses each having a second focal length negative or longer than that of said convex lenses of said first lens group.

2. A device according to claim 1, wherein in said second lens array, said lenses of said first lens group and said lenses of said second lens group are arranged in alternate and staggered manner.

3. A luminaire comprising:

a light source;

a collimator for collimating light emitted from said light source by reflecting or refracting; and

an illuminance distribution improving device disposed so as to receive light from said collimator,

wherein said illuminance distribution improving device comprises;

a first lens array, having a plurality of convex lenses each having a first focal length, receiving light from said collimator;

a second lens array, having a plurality of lenses corresponding to respective lenses of said first lens array, disposed opposite to said first lens array; and

a condenser lens disposed on the opposite side to said first lens array with respect to said second lens array,

wherein a distance between said first and second lens arrays is substantially equal to said first focal length,

wherein said second lens array has;

a first lens group composed of a plurality of convex lenses each having a second focal length; and

a second lens group composed of a plurality of lenses each having a second focal length negative or longer than that of said convex lenses of said first lens group.