Temperature-Responsive Lighting Control for Color Uniformity
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Solution Overview
Problem
Solid state lighting apparatus struggle to produce white light with high color rendering index, as existing solutions using blue-shifted-yellow light sources often result in low color rendering indices, and there is a need for control of optical output uniformity over varying operating temperatures.
Innovation Solution
A lighting apparatus comprising multiple light emitting devices with different chromaticities, a temperature sensor, and a compensation circuit that adjusts the electrical current through these devices to maintain color uniformity and adjust the color output based on temperature changes, ensuring a consistent and high color rendering index across temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple light emitting devices with different chromaticities are combined to improve color rendering index, then color rendering index is improved, but device complexity increases
Solution Approach 1:
The lighting apparatus divides the light emitting function into multiple separate light emitting devices, each with a specific chromaticity (first, second, and third chromaticities). This segmentation allows independent control and optimization of each device's contribution to the overall color output, enabling high CRI while maintaining manageable system complexity through modular design.
Solution Approach 2:
The control circuit provides multi-functional capability by simultaneously performing current regulation for multiple light emitting devices, color temperature control, and CRI optimization. This universal control approach consolidates multiple functions into a single circuit, improving CRI without proportionally increasing device complexity.
2Illumination intensity
If light emitting devices are operated at high current to increase illumination intensity, then illumination intensity is improved, but color uniformity deteriorates due to temperature variations
Solution Approach 1:
The control circuit implements feedback control by continuously monitoring the operating conditions of multiple light emitting devices with different chromaticities and dynamically adjusting their current distribution. This feedback mechanism maintains color uniformity across varying illumination intensities by compensating for temperature-induced chromaticity shifts in real-time.
Solution Approach 2:
The system transitions from static current operation to dynamic current control, where the control circuit continuously adapts the current through each light emitting device based on operating conditions. This dynamic adjustment ensures color uniformity is maintained even as illumination intensity and temperature vary during operation.
3Device complexity
If blue-shifted-yellow light sources are used to simplify the lighting apparatus, then device complexity is reduced, but color rendering index deteriorates
Solution Approach 1:
The lighting apparatus uses a composite approach by combining multiple light emitting devices with different chromaticities (first, second, and third chromaticities) rather than relying on a single blue-shifted-yellow source. This composite structure synthesizes a broader spectrum light output that achieves high color rendering index while maintaining practical device complexity through integrated design.
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 provides a lighting apparatus that generates white light with improved color rendering index and uniformity by dynamically adjusting the current through red and blue-shifted-yellow light emitting devices in response to temperature changes, maintaining a consistent color output even at varying temperatures.
Implementation Method 1
a temperature sensor configured to generate a temperature sense signal responsive to heat generated by at least one of the plurality of light emitting devices
Implementation Method 2
a compensation circuit configured to vary a level of electrical current through the third light emitting device relative to the electrical current through the first and second light emitting devices responsive to the temperature sense signal
Implementation Method 3
a first light emitting device configured to emit light having a first chromaticity, a second light emitting device configured to emit light having a second chromaticity different than the first chromaticity
Implementation Method 4
solid state light emitting device generates light through the recombination of electronic carriers, i.e. electrons and holes, in a light emitting layer or region
Data Source
AI summary
A lighting apparatus may include a plurality of light emitting devices, a temperature sensor, and a compensation circuit. The plurality of light emitting devices may include a first light emitting device configured to emit light having a first chromaticity, a second light emitting device configured to emit light having a second chromaticity different than the first chromaticity, and a third light emitting device configured to emit light having the second chromaticity. Moreover, the first, second, and third light emitting devices may be electrically coupled in series. The temperature sensor may be configured to generate a temperature sense signal responsive to heat generated by at least one of the plurality of light emitting devices. The compensation circuit may be coupled to the third light emitting device, with the compensation circuit being configured to vary a level of electrical current through the third light emitting device relative to the electrical current through the first and second light emitting devices responsive to the temperature sense signal. Related methods are also discussed.