Illumination device, luminaire and lighting system
An illumination device comprises a housing ( 5 ) with a plurality of compartments ( 3 ), each compartment comprising a respective light emission window ( 15 ), a light source ( 11 ), and a stack of crossed prismatic sheets ( 10 ). Light issued by the light source during operation is made to propagate through the prismatic sheets and subsequently through the light emission window. The orientation of the stack of sheets is different for each compartment, thus causing each compartment to issue a different beam of light. The light source of each compartment is separately switchable, thus enabling easy setting of the type of beam issued form the illumination device. Optionally a diffuser ( 17, 23 ) is provided at one side or at both sides of the stack of prismatic sheets to enhance the homogeneity of the issued light.
1. An illumination device comprising a housing with at least a first compartment and a second compartment, the first compartment comprising:
a light emission window bordered by an outer edge of the compartment;
a carrier for at least one light source;
a stack of crossed prismatic sheets positioned in the housing, each sheet having a smooth side and a grooved side;
wherein light issued by the tight source during operation is made to propagate along a light path, said light path extending from the light source through the prismatic sheets and subsequently through the light emission window at least partially along a central axis transverse to the light emission window, both prismatic sheets being turned with the smooth side towards the light emission window, and
wherein, in the second compartment, at least one prismatic sheet is turned with its grooved side towards the light emission window.
2. The illumination device as claimed in claim 1 , wherein a third compartment is provided.
3. The illumination device as claimed in claim 2 , wherein both in the second and third compartment one prismatic sheet is turned with its grooved side towards the light emission window.
4. The illumination device as claimed in claim 3 , wherein the stack of crossed prismatic sheets in the second compartment and the stack of crossed prismatic sheets in the third compartment are mutually rotated through 90° around a rotation axis that extends parallel to the central axis.
5. The illumination device as claimed in claim 4 , wherein the first compartment is closely fitted in between the second and the third compartment.
6. The illumination device as claimed in claim 5 , wherein the first compartment is enclosed by the second and third compartment, the second and third compartment being congruently shaped and positioned so as to be each other's mirror image.
7. The illumination device as claimed in claim 1 , wherein the stack of prismatic sheets of the second compartment comprises at least three sheets, two of the prismatic sheets are crossed and are turned with their respective grooved side towards the light emission window.
8. The illumination device as claimed in claim 1 , wherein a difffuser is provided at one side or at both sides of the stack of prismatic sheets.
9. The illumination device as claimed in claim 1 , wherein the light source of each compartment is separately switchable.
10. The illumination device as claimed in claim 1 , wherein each compartment is provided with a light-transmissible plate positioned in its respective light emission window and facing with a first side towards the exterior and with a second side towards the interior of the housing.
11. The illumination device as claimed in claim 10 , wherein the respective plates of each compartment together are formed into one integral plate.
12. The illumination device as claimed in claim 1 , wherein the compartments are mutually separated by a light reflective wall.