LED lighting unit

1. An LED lighting unit comprising:

a container with a number of partially reflective side walls;

a light exit opening defined by the side walls; and

a number of light-emitting diodes arranged in the container to emit light of a first color through the light exit opening during an on-state of the lighting unit;

wherein the material properties of the partially reflective container side walls are chosen to impart a second non-white color to the container side walls, and to absorb light in at least one specific region of the visible spectrum such that light of the non-white second color exits the lighting unit through the light exit opening during an off-state of the lighting unit;

wherein the number of light-emitting diodes comprises a plurality of red light-emitting diodes; and

wherein the material properties of the partially reflective container side walls are chosen to impart one of:

a green color to the container side walls and to absorb light of a first specific region of the visible spectrum in a wavelength range of 380-480 nm; and to absorb light of a second specific region of the visible spectrum in a wavelength range of 540-630 nm;

a yellow color to the container side walls and to absorb light of a specific region of the visible spectrum in a wavelength range of 400-520 nm; or

a blue color to the container side walls and to absorb light of a specific region of the visible spectrum in a wavelength range of 550 nm-640 nm.

2. The LED lighting unit according to claim 1 , wherein the partially reflective container side walls comprise a Distributed Bragg Reflector coating applied to an underlying black material.

3. The LED lighting unit according to claim 1 , wherein the partially reflective container side walls comprise multiple layers of SiO2 and ZrO2 material.

4. The LED lighting unit according to claim 1 , partially reflective container side walls comprise a potassium permanganate pigment.

5. The LED lighting unit according to claim 1 , comprising a flexible filler arranged to cover the LEDs.

6. The LED lighting unit according to, claim 1 , wherein the material of at least the container is sufficiently flexible to impart flexibility to the LED lighting unit.

7. A method of manufacturing an LED lighting unit, which method comprises the steps of:

constructing a container with a number of partially reflective side walls arranged to define a light exit opening; and

arranging a number of light-emitting diodes in the container to emit light of a first color through the light exit opening during an on-state of the lighting unit;

wherein the material properties of the container side walls are chosen to impart a second non-white color to the container side walls, and

absorb light in at least one specific region of the visible spectrum such that light of the non-white second color exits the lighting unit through the light exit opening during an off-state of the lighting unit,

wherein the number of light-emitting diodes comprises a plurality of red light-emitting diodes; and

wherein the material properties of the partially reflective container side walls are chosen to impart one of:

a green color to the container side walls and to absorb light of a first specific region of the visible spectrum in a wavelength range of 380-480 nm; and to absorb light of a second specific region of the visible spectrum in a wavelength range of 540-630 nm;

a yellow color to the container side walls and to absorb light of a specific region of the visible spectrum in a wavelength range of 400-520 nm; or

a blue color to the container side walls and to absorb light of a specific region of the visible spectrum in a wavelength range of 550 nm-640 nm.