| 摘要 |
PCT No. PCT/AU90/00408 Sec. 371 Date Apr. 8, 1992 Sec. 102(e) Date Apr. 8, 1992 PCT Filed Sep. 7, 1990 PCT Pub. No. WO91/03682 PCT Pub. Date Mar. 21, 1991.There is provided illuminating apparatus including an illuminating channel 10 defined between an incident surface 11, an emergent surface 12, an upper surface 13 and a lower surface 14. The upper surface 13 includes end portions 15 which may be adhered to the lower end portions 16 of an adjacent illuminating channel. The portion of the upper surface 13 between the end portions 15 comprises a steeply inclined outer portion 17, a horizontal central portion 20 and a shallow inner inclined portion 21. Light entering the incident face 31 at a low angle of incidence is reflected by total internal reflection in turn from the lower outer surface 32 of a first cavity 33, the central portion of the upper surface 34 of a second cavity 35, and then the inner lower surface 36 of the first cavity 33 before emerging from the emergent face 37. Light entering the incident face 31 at a medium angle of incidence is refracted at the incident face to a lower angle of refraction such that most incident light is reflected from locations distributed along the upper surface 40 of the cavity 41. Light entering the incident face 31 at a high angle of incidence is refracted to a lower angle such that most incident light falls on the outer end of the upper surface 42 of the cavity 43, such that the light rays are deflected through an angle sufficient for them to emerge from the emergent face 37 diffused and approximately perpendicular to the latter.
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