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US 9,312,451 B2Granted
Apparatus, method to enhance color contrast in phosphor-based solid state lights
AssigneeExpress Imaging Systems, LLC
InventorsWilliam G. Reed, John O. Renn
Life of this patent
Estimating the term…
Abstract
The efficiency and color contrast 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 double-notch reflective filter may pass desired wavelengths such as red and green, while returning or reflecting less desired wavelengths (blue and yellow) away from an optical exit back toward wavelength shifting material and re-emitted as light of more desirable wavelengths.
Claims33
A lighting device, comprising:
- an active light source operable to emit light across a plurality of wavelengths;
- at least one double-notch reflective filter that substantially passes light of a first set of wavelengths in the plurality of wavelengths and that substantially reflects light of a second set of wavelengths in the plurality of wavelengths, the second set of wavelengths including a first rejection band of about 400 nm to 480 nm and a second rejection band of about 570 nm to 600 nm, the at least one double-notch 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 double-notch reflective filter and in response emit light at wavelengths shifted from respective first rejection band and the second rejection band toward an optical exit of the lighting device.
1 more element
A light emitting diode package, comprising:
- a substrate;
- at least one light emitting diode carried by the substrate;
- at least one double-notch 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 a second set of wavelengths in the plurality of wavelengths, wherein the second set of wavelengths includes a first rejection band having a bandwidth of 400 nm to 480 nm with a first center wavelength (λc1) at about 450 nm and a second rejection band having a bandwidth of 570 nm to 600 nm with a second center wavelength (λc2) at about 585 nm;
- and
- at least one wavelength shifter positioned with respect to the at least one light emitting diode and the at least one double-notch reflective filter, the at least one wavelength shifter is configured to receive at least some of the light emitted by the at least one light emitting diode and to receive at least some of the second set of wavelengths reflected from the at least one double-notch reflective filter and in response emit light at wavelengths shifted from the respective first rejection band and the second rejection band.
2 more elements
Dependencies are inferred from the claim text.