Optical Element with Light Transmitting Walls for Color Uniformity
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Solution Overview
Problem
Existing lighting assemblies with phosphor converted light sources experience significant color over angle variation, leading to non-uniform color emission at different light emission angles, which current technologies attempt to correct using reflectors or lenses but with limited success.
Innovation Solution
A lighting assembly comprising a solid state light emitter and a luminescent element, combined with an optical element featuring light transmitting walls that reduce color over angle variation by selectively reflecting and transmitting light, ensuring a more uniform color output across various angles through a channel structure and materials like transparent polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a phosphor layer is used to convert LED light, then white light emission is obtained, but color over angle variation occurs
Solution Approach 1:
An optical element is introduced as an intermediary component between the phosphor layer and the external environment. This optical element receives light from the phosphor layer and modifies its angular distribution, allowing light of different colors emitted at different angles to be mixed uniformly before exiting the device, thereby reducing color over angle variation while maintaining white light emission.
2Stability of the object's composition
If a reflector or lens is used to correct color over angle variation, then color uniformity improves, but device complexity increases
Solution Approach 1:
The optical element is designed to perform multiple functions simultaneously: it acts as a light transmitter, an angular distributor, and a color mixer all in one component. By integrating these functions into a single element rather than using separate reflectors and lenses, the device achieves color uniformity while minimizing the increase in overall device complexity.
3Stability of the object's composition
If light transmitting walls are used in the optical element, then color over angle variation is reduced, but light transmission efficiency decreases
Solution Approach 1:
The optical element features light transmitting walls with specific local properties - they are positioned and dimensioned to selectively transmit light of different colors from different angles. The walls are designed with precise geometric characteristics that allow them to redirect and mix specific angular components while maintaining overall light transmission efficiency, rather than blocking all light uniformly.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces color over angle variation, enhancing the color uniformity of the light emitted by the lighting assembly while maintaining high efficiency and preventing excessive collimation, with the optical element reflecting between 5% and 20% of impinging light to achieve a more uniform color output.
Implementation Method 1
The luminescent element comprises luminescent material for absorbing a portion of the light of the first color and for converting a portion of the absorbed light towards light of a second color
Implementation Method 2
Light with light rays that have larger light emission angles impinges on the light transmitting walls. Although the surface of the walls may look relatively flat, seen at the micro level there may be some roughness and, consequently, the walls may also reflect some light rays impinging at an angle smaller than the critical angle
Implementation Method 3
After the transmission through the wall the light rays may impinge on the light transmitting wall at another location, where, again, an (limited) amount of transmitted light rays may be reflected, while also a portion of it is transmitted to the other side of the wall
Data Source
AI summary
A lighting assembly (100), a lamp, a luminaire, a manufacturing method and a manufacturing control program are provided. The lighting assembly comprises a light source (110) and an optical element (120). The light source comprises a solid state light emitter (112) and a luminescent element (114). The solid state light emitter is arranged to emit light of a first color into the luminescent element. The luminescent element comprises a light emission window (115) through which the light is emitted. The optical element is arranged for reducing a color over angle variation of the light emitted by the light emission window of the luminescent element. The optical element comprises a light input face, a light output face and at a plurality of locations a light transmitting wall (122) extending from the light input face to the light output face.