Solid State Lighting Bypass Circuits for Color Rendering
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Solution Overview
Problem
Solid state lighting devices, such as LED-based systems, often have a low color rendering index (CRI), which limits their ability to accurately illuminate a broad range of colors, making them less effective for applications requiring natural color representation.
Innovation Solution
A lighting apparatus with a string of serially-connected light emitting device sets, including controllable bypass circuits that allow for variable current bypassing around specific LEDs, enabling adjustment of color points based on temperature, current, and other inputs to enhance CRI and achieve desired color outputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If red, green and blue light emitting devices are energized simultaneously to generate white light, then the color rendering index is improved, but the device complexity increases due to multiple light emitting devices and control circuits
Solution Approach 1:
The lighting apparatus divides the light emitting devices into multiple sets with different color points (e.g., first set with first color point, second set with second color point). Each set can be independently controlled through separate bypass circuits, allowing precise color mixing to achieve high CRI white light without requiring all devices to operate at full complexity simultaneously
Solution Approach 2:
The bypass circuits provide dynamic control over the current flowing to each light emitting device set. By adjusting the bypass amount responsive to control inputs, the system can dynamically change the relative intensities of different color point devices, enabling flexible color point adjustment and high CRI achievement without fixed complex wiring
2Adaptability or versatility
If controllable bypass circuits are added to adjust color points, then the color rendering index and adaptability are improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The bypass circuits are designed to perform multiple functions: they control current distribution to different color point devices, enable color point adjustment, and can operate with various control inputs (temperature, current, light, adjustment signals). This multi-functionality reduces the need for separate dedicated circuits for each function, simplifying manufacturing while maintaining high adaptability
Solution Approach 2:
The system achieves color point adjustment by changing the electrical parameters (current distribution) rather than physically reconfiguring the device. The bypass circuits modify the operating parameters of existing light emitting devices, allowing flexible color control without requiring complex mechanical or structural changes during manufacturing
3Reliability
If multiple light emitting device sets with different color points are used, then the color rendering index is improved, but the loss of energy increases due to current bypassing
Solution Approach 1:
The bypass circuits operate responsive to control inputs that can include light sensors, temperature sensors, and current sensors. This feedback mechanism allows the system to optimize the bypass amount in real-time, directing current efficiently to the light emitting device sets that are most effective for achieving the desired color point, thereby minimizing energy waste while maintaining high CRI
Solution Approach 2:
The system dynamically changes the operating parameters (current distribution) of light emitting device sets based on environmental conditions and desired output. By adjusting which devices receive current and at what levels, the system optimizes energy utilization to achieve high CRI without excessive energy loss from bypassing
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 improves the color rendering index of solid state lighting systems by allowing for precise control of color points, resulting in more natural color representation and improved luminous efficacy, even under varying conditions.
Implementation Method 1
a bypass circuit having a controllable amount of electrical resistance coupled across a subset of the light emitting devices
Implementation Method 2
a 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 includes a string with a plurality of serially-connected light emitting device sets, each set comprising at least one light emitting device. The apparatus further includes at least one controllable bypass circuit configured to variably bypass current around at least one light emitting device of a set of the plurality of light emitting device sets responsive to a control input. The control input may include, for example, a temperature input, a string current sense input and/or an adjustment input. The control input may be varied, for example, to adjust a color point of the string.