Device having a partially reflective cover

1. Device having a partially reflective cover comprising:

a light source; and

a cover which is arranged in front of the light source, the cover being exposed to incident non-polarized ambient light,

wherein the cover comprises a reflective polarizer and a circular polarizer, the reflective polarizer being arranged on a side of the cover exposed to the incident non-polarized ambient light, and the circular polarizer being arranged behind the reflective polarizer on an opposite side of the cover on which light of the light source falls, and

wherein the reflective polarizer comprises a dielectric multi-layer mirror that predominately reflects the incident non-polarized ambient light in the visible wavelength range that falls on the reflective polarizer and has high transmissivity for light of at least one visible wavelength emitted by the light source and polarized by the circular polarizer.

2. Device according to claim 1 , wherein the circular polarizer comprises a linear polarizer and a quarter-wave layer.

3. Device according to claim 1 , wherein the cover further comprises a half-wave layer.

4. Device according to claim 3 , wherein the half-wave layer is part of the circular polarizer.

5. Device according to claim 1 , wherein the light source comprises a light-emitting diode.

6. Device according to claim 1 , wherein the light source comprises an organic light-emitting diode-, OLED-, film.

7. Device according to claim 1 , wherein the device further comprises a liquid crystal display which is arranged in front of the light source, and wherein the light of the light source that is transmitted by the liquid crystal display is polarized.

8. Device according to claim 1 , wherein a light guide is arranged on a front face of the light source.

9. Device according to claim 8 , wherein the light guide is configured to homogenise the light emitted by the light source over the surface.

10. Device according to claim 1 , wherein the light source emits polarized light, and wherein the polarization of the emitted light and the circular polarizer of the device are so matched to one another that high transmission of the emitted light through the circular polarizer takes place.

11. Device according to claim 10 , wherein the reflective polarizer is transparent to light that is emitted by the light source and transmitted by the circular polarizer.

12. Device according to claim 1 , further comprising a transparent covering layer which is arranged in front of the reflective polarizer.

13. Device according to claim 1 , further comprising a non-transparent diaphragm, wherein the non-transparent diaphragm is arranged in front of the reflective polarizer, and wherein the non-transparent diaphragm partially covers a front face of the reflective polarizer.

14. Device according to claim 13 , wherein the diaphragm is so configured that part of the front face of the reflective polarizer that is covered or not covered by the diaphragm has the form of a logo.

15. Light-emitting element, in particular decorative element, comprising a device according to claim 1 .

16. Mobile device comprising a light-emitting element according to claim 15 .

17. Motor vehicle comprising a light-emitting element according to claim 15 .

18. Method of using a cover, wherein the cover is exposed to incident non-polarized ambient light and comprises a reflective polarizer and a circular polarizer; comprising:

arranging the cover in front of a light-emitting element; and

emitting light from the light-emitting element through the cover,

wherein the reflective polarizer is arranged on a side of the cover exposed to the incident non-polarized ambient light, and the circular polarizer is arranged behind the reflective polarizer on an opposite side of the cover on which the light emitted by the light-emitting element falls,

wherein the reflective polarizer comprises a dielectric multi-layer mirror that predominately reflects the incident non-polarized ambient light in the visible wavelength range that falls on the reflective polarizer and has high transmissivity for light of at least one visible wavelength emitted by the light-emitting element and polarized by the circular polarizer.