LED Module Thermistor Feedback for Red Light Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light-emitting modules experience a reduction in red light output due to temperature variations, which affects their ability to maintain a high color rendering index (CRI).
Innovation Solution
A light-emitting module design that includes a thermistor connected in parallel with a light-emitting element, a first on/off control unit to compensate for temperature-induced current variations, and a second on/off control unit to manage current flow through other light-emitting elements, ensuring consistent color coordinates by adjusting current paths based on temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional LED driving device is used, then the structure is simple, but the output of red light is reduced as temperature increases, making it impossible to provide a high color rendering index
Solution Approach 1:
The patent employs a feedback mechanism where the dimming signal is used to control the current supplied to the red LED. The controller adjusts the red LED current based on the dimming signal level, creating a feedback loop that compensates for temperature-induced output reduction. This ensures the red light output remains stable across varying temperatures while maintaining the desired color rendering index.
Solution Approach 2:
The patent changes the electrical parameters (current) supplied to the red LED based on temperature conditions and dimming signals. By dynamically adjusting the red LED current parameter in response to temperature variations and dimming requirements, the system maintains consistent red light output and achieves high color rendering index regardless of temperature changes.
2Illumination intensity
If separate channels for red and white LEDs are provided, then a high color rendering index can be realized, but the device complexity increases
Solution Approach 1:
The patent combines the control of red and white LEDs under a unified controller that responds to a single dimming signal. By merging the control functions and using a shared dimming signal pathway, the system achieves high color rendering index through separate red and white LED channels while minimizing the overall device complexity and control structure.
3Illumination intensity
If the red LED current is increased to maintain output at high temperatures, then the color rendering index is maintained, but the energy consumption increases
Solution Approach 1:
The patent applies partial action by selectively adjusting only the red LED current in response to dimming signals, rather than increasing the current for all LEDs. This targeted approach maintains the color rendering index by compensating for red LED output reduction at high temperatures, while avoiding unnecessary energy consumption by other LED channels that are already operating at optimal levels.
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 module maintains a high color rendering index of 90 or more and ensures consistent color reproducibility across temperature changes, preventing a reduction in red light output, thereby enhancing efficiency and cost-effectiveness.
Implementation Method 1
a thermistor connected in parallel with a light-emitting element
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
A light emitting module of an embodiment comprises: (1-1)th to (1-M)th(where M is a positive integer equal to or greater than 2) light emitting elements connected with each other; (2-1)th to (2-N)th (where N is a positive integer equal to or greater than 1) light emitting elements connected in parallel with a (1-m)th (1≤m≤M) light emitting elements which is one of the (1-1)th to (1-M)th light emitting elements; and an on/off control unit for controlling to turn the (1-1)th to (1-M)th light emitting elements and (2-1)th to (2-N)th light emitting elements on or off according to a level of a driving signal. The on/off control unit comprises a first on/off control unit for controlling to turn the (1-m)th light emitting element and (2-1)th to (2-N)th light emitting elements on or off, and a second on/off control unit for controlling to turn the remaining light emitting elements on or off, excluding the (1-m)th light emitting element among the (1-1)th to (1-M)th light emitting elements, wherein the first on/off control unit compensates for a variation in second current, which flows through the (2-1)th to (2-N)th light emitting elements, depending of temperature in conjunction with a first current, which flows through the (1-m)th light emitting element.