Controlling off-state appearance of a light emitting device
Systems for apparatuses formed of light emitting devices. Solutions for controlling the off-state appearance of lighting system designs is disclosed. Thermochromic materials are selected in accordance with a desired off-state of an LED device. The thermochromic materials are applied to a structure that is in a light path of light emitted by the LED device. In the off-state the LED device produces a desired off-state colored appearance. When the LED device is in the on-state, the thermochromic materials heat up and become more and more transparent. The light emitted from the device in its on-state does not suffer from color shifting due to the presence of the thermochromic materials. Furthermore, light emitted from the LED device in its on-state does not suffer from attenuation due to the presence of the thermochromic materials. Techniques to select and position thermochromic materials in or around LED apparatuses are presented.
1. A structure comprising:
a semiconductor light emitting device;
a transparent structural member adjacent to the semiconductor light emitting device in a path of light emitted by the semiconductor light emitting device;
a conductive film disposed on the transparent structural member; and
a layer of thermochromic material in direct contact with the transparent structural member or the conductive film, the thermochromic material having a colored state and a transparent or translucent state;
the conductive film configured to heat by ohmic heating the layer of thermochromic material when the semiconductor light emitting device is turned on causing the thermochromic material to transition from the colored state to the transparent or translucent state.
2. The structure of claim 1 , further comprising a wavelength converting material disposed between the semiconductor light emitting device and the layer of thermochromic material.
3. The structure of claim 2 , wherein the layer of thermochromic material is in direct contact with the wavelength converting material.
4. The structure of claim 2 , wherein the layer of thermochromic material thermochromic is spaced apart from the wavelength converting material.
5. The structure of claim 1 , further comprising a lens disposed in the path of light emitted by the semiconductor light emitting device, and a second layer of thermochromic material is disposed on the lens.
6. The structure of claim 1 , wherein the colored state includes one of a blue appearance, a black appearance, or a red appearance.
7. A structure comprising:
a semiconductor light emitting device;
a transparent structural member adjacent to the semiconductor light emitting device in a path of light emitted by the semiconductor light emitting device;
a conductive wire in contact with the transparent structural member; and
a layer of thermochromic material in direct contact with the transparent structural member, the thermochromic material having a colored state and a transparent or translucent state;
the conductive wire configured to heat by ohmic heating the layer of thermochromic material when the semiconductor light emitting device is turned on causing the thermochromic material to transition from the colored state to the transparent or translucent state.
8. The structure of claim 7 , wherein the conductive wire is embedded in the transparent structural member.
9. The structure of claim 7 , wherein the conductive wire is disposed on the transparent structural member.
10. The structure of claim 7 , further comprising a wavelength converting material disposed between the semiconductor light emitting device and the layer of thermochromic material.
11. The structure of claim 7 , further comprising a lens disposed in the path of light emitted by the semiconductor light emitting device, and a second layer of thermochromic material is disposed on the lens.
12. The structure of claim 7 , wherein the colored state includes one of a blue appearance, a black appearance, or a red appearance.