LED Bulb Voltage Control via Temperature Feedback
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Solution Overview
Problem
LED light bulb manufacturers face challenges in meeting rebate standards due to the wide tolerance in forward operating voltage of LEDs, leading to inefficiencies and increased costs, as they must either apply excessive voltage to ensure all LEDs operate or sort LEDs by voltage, which is costly.
Innovation Solution
The design of an LED light bulb with independent power connections for series strings of LEDs of different color temperatures, equipped with a temperature sensor and a minimum voltage indicator, allows for dynamic adjustment of voltage based on temperature to optimize light output efficacy without excessive power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage is applied sufficient to ensure all LEDs operate at their forward operating voltage over the entire temperature range, then all LEDs will be turned on, but significant power losses occur as most LEDs dissipate excess power
Solution Approach 1:
The patent applies dynamics by making the voltage applied to the LED string variable rather than fixed. The voltage is dynamically adjusted based on the actual forward operating voltage of the LED string, which changes with temperature. The power supply continuously monitors and adapts the output voltage to match the LED string's requirements, avoiding both excessive voltage (which causes power loss) and insufficient voltage (which causes LEDs to fail to operate).
Solution Approach 2:
The patent implements feedback by having the power supply continuously monitor the actual forward operating voltage of the LED string and adjust its output accordingly. The system measures the voltage drop across the LED string and uses this information to regulate the applied voltage, ensuring it matches the LED string's actual needs rather than applying a fixed worst-case voltage. This feedback mechanism eliminates the need to overdrive the LEDs while maintaining reliable operation.
2Loss of energy
If LEDs are sorted by forward operating voltage to enable precise voltage control, then power efficiency improves, but manufacturing cost increases due to testing and sorting requirements
Solution Approach 1:
The patent applies self-service by enabling the LED string to effectively 'sort itself' through dynamic voltage adjustment. Rather than requiring manual sorting of LEDs during manufacturing, the power supply adapts to the actual characteristics of the LED string in service. The system automatically determines the appropriate voltage level based on the LED string's real-time electrical characteristics, eliminating the need for costly pre-sorting while achieving similar efficiency benefits.
Solution Approach 2:
The patent implements parameter changes by allowing the operating voltage parameter to vary dynamically rather than being fixed at a predetermined value. The power supply adjusts the voltage parameter based on the actual forward operating voltage of the LED string, which may differ from typical values due to manufacturing tolerances, temperature, and aging. This approach replaces the need for sorting (which fixes the voltage parameter) with dynamic adaptation (which allows the parameter to change).
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
This approach enhances light output efficacy by adjusting voltage according to temperature, reducing waste and costs associated with sorting LEDs, while maintaining high efficiency and allowing for variable color temperature control.
Implementation Method 1
The LED bulb includes a temperature sensor that provides an electrical indication of a present temperature of the LED bulb
Implementation Method 2
LED light bulbs have become a preferred lighting technology over incandescent light bulbs
Implementation Method 3
increasing the current through an LED beyond that needed to achieve the forward operating voltage does not produce a corresponding output in light
Data Source
AI summary
An LED bulb includes one or more LEDs that have a forward voltage that is dependent on the thermal temperature of the LEDs. In some embodiments the LED bulb includes a temperature sensor that provides an indication of LED temperature to a power supply so that the voltage provided to the LED bulb by the power supply is optimized and adjusted with respect to temperature so that only the voltage needed by the LED bulb to power the LEDs to an desired light output level is provided to the LEDs, and overhead voltage is minimized.