The present invention relates to a luminaire comprising one or more LED light sources ( 102 ) arranged within a light chamber that is enclosed by a translucent cover ( 302 ), having an inner surface ( 308 ), wherein the LED light source ( 102 ) is arranged to illuminate the inner surface ( 308 ) of the translucent cover ( 302 ). The translucent cover ( 302 ) comprises a prismatic optical structure ( 304 ) on the inner surface ( 308 ) for reflecting and/or refracting light from the LED light source ( 102 ) omni-directionally. The prismatic optical structure ( 304 ) is designed such that a direct view of the LED light source from outside the luminaire is obstructed by means of total internal reflection at the prismatic optical structure.
1. A luminaire comprising:
a light chamber,
a translucent cover enclosing the light chamber, the translucent cover having an inner surface, and
a LED light source arranged within the light chamber to illuminate the inner surface of the translucent cover,
wherein the translucent cover comprises a material having a first refractive index (n 1 ), and wherein the light chamber comprises a material having a second refractive index (n 2 ), and
wherein the translucent cover comprises a prismatic optical structure on the inner surface, the prismatic optical structure having a top angle that is equal to or smaller than 2×[90−arcsin(n 2 /n 1 )].
2. The luminaire according to claim 1 , wherein the translucent cover is cylindrical.
3. The luminaire according to claim 1 , wherein the LED light source comprises at least two LEDs arranged within the translucent cover.
4. The luminaire according to claim 3 , wherein two LEDs are arranged back to back on a two-sided PCB, and wherein the PCB is in thermal contact with a heat conducting material.
5. A luminaire comprising:
a light chamber,
a translucent cover enclosing the light chamber, the translucent cover having an inner surface, and
a LED light source arranged within the light chamber to illuminate the inner surface of the translucent cover,
wherein the translucent cover consists of a material having a first refractive index (n 1 ), and wherein the light chamber comprises a material having a second refractive index (n 2 ), and
wherein the translucent cover comprises a prismatic optical structure on the inner surface, the prismatic optical structure having a top angle that is equal to or smaller than 2×[90−arcsin(n 2 /n 1 )].
6. The luminaire according to claim 5 , wherein the translucent cover is a one-piece molded cover, formed by an injecting moulding process.