Apparatus, method to change light source color temperature with reduced optical filtering losses
AssigneeExpress Imaging Systems, LLC
InventorsWilliam G. Reed, John O. Renn
Life of this patent
Estimating the term…
Abstract
The efficiency and color temperature of a lighting device may be improved by using wavelength shifting material, such as a phosphor, to absorb less desired wavelengths and transmit more desired wavelengths. A reflective filter (e.g., dichroic or dielectric mirror material) may pass desired wavelengths while returning or reflecting less desired wavelengths away from an optical exit back toward wavelength shifting material which may either be disposed in the optical path or on the periphery of the light source.
Claims35
A lighting device, comprising:
- an active light source operable to emit light across a plurality of wavelengths;
- at least one reflective filter that substantially passes light of a first set of wavelengths in the plurality of wavelengths and that substantially returns light of second set of wavelengths in the plurality of wavelengths, the at least one reflective filter positioned in an optical path between the active light source and an exterior of the lighting device to filter the light before the light reaches the exterior of the lighting device;
- and
- a wavelength shifter positioned and oriented to receive at least some of the light of the second set of wavelengths returned from the at least one reflective filter and in response emit light at a shifted wavelength toward an optical exit of the lighting device.
A method of producing a lighting device, the method comprising:
- positioning at least one reflective filter in an optical path between an active light source and an exterior of the lighting device to filter light before the light reaches the exterior of the lighting device, the at least one reflective filter transmitting a first set of wavelengths to the exterior of the lighting device and returning a second set of wavelengths away from the exterior of the lighting device;
- and
- positioning and orienting a first wavelength shifter to receive at least some of the light of the second set of wavelengths returned from the at least one reflective filter and in response emit light at a shifted wavelength toward an optical exit of the lighting device.
A light emitting diode package, comprising:
- a substrate;
- at least one light emitting diode carried by the substrate;
- at least one reflective filter positioned with respect to the light emitting diode to substantially pass light of a first set of wavelengths in the plurality of wavelengths and substantially return light of second set of wavelengths in the plurality of wavelengths;
- and
- at least one wavelength shifter positioned with respect to the at least one light emitting diode and the at least one reflective filter to receive at least some of the light of the emitted by the at least one light emitting diode and to receive at least some of the second set of wavelengths returned from the at least one reflective filter and in response emit light at a shifted wavelength.
Dependencies are inferred from the claim text.