Multi-layered collimator
A collimator for use in an optical device, such as a display device, includes a multi-layered sheet of at least five alternating light transmitting and light impervious layers. A collimation angle of a few degrees is obtainable using the collimator. The collimator may be produced by co-extruding or injection molding.
1. A collimator for use in an optical device comprising a multi-layered sheet of alternating light transmitting and light impervious layers, wherein each light impervious layer comprises a first section of light scattering material and a second section of light absorbing material.
2. The collimator according to claim 1 , wherein said multi-layered sheet comprises at least two light transmitting layers and at least three light impervious layers.
3. The collimator according to claim 1 , wherein the light transmitting layers are made of at least one transparent amorphous polymeric material.
4. The collimator according to claim 1 , wherein the light impervious layers are made of at least one light absorbing and/or light scattering polymeric material.
5. The collimator according to claim 1 , wherein the light impervious layers are made of a polymer matrix comprising at least one type of light absorbing and/or light scattering particle or compound.
6. The collimator according to claim 1 , which comprises projecting parts of the light transmitting layers on a side of the collimator intended to face a light source, each layer part having a lens-shaped end.
7. A method for producing a collimator comprising a multi-layered sheet of alternating light transmitting and light impervious layers, the method comprising the act of co-extruding a melt of at least one light transmitting polymeric material and at least one light impervious polymeric material into a multi-layered sheet.
8. A method for producing a collimator comprising a multi-layered sheet of alternating light transmitting and light impervious layers, the method comprising the acts of:
injection molding a melt of at least one light transmitting polymeric material into layers separated by vacant spaces and connected by a common base part, and
filling a melt of at least one light impervious polymeric material into the vacant spaces thus providing a multi-layered sheet.
9. A display device comprising a collimator according to claim 1 .
10. An illumination device comprising a collimator according to claim 1 .
11. An optical touch sensitive device comprising a collimator according to claim 1 .