Vehicle Lamp Derating Control for Heat and Illuminance Conditions
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Solution Overview
Problem
Existing vehicle lamp systems fail to effectively suppress thermal degradation of light-emitting elements and peripheral components due to high temperatures, particularly in environments with varying illuminance levels, leading to potential thermal degradation and reduced luminous flux without adequately addressing the need for maintaining forward field of view.
Innovation Solution
A vehicle lamp system that includes a temperature sensor to measure the temperature of the light source or its surroundings, reducing the drive current when the temperature exceeds a control start temperature, and adjusts this start temperature based on the illuminance threshold, ensuring derating control is initiated earlier in high-illuminance conditions to prevent thermal degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If derating control is initiated at a high control start temperature to maintain luminous flux, then the forward field of view is preserved, but thermal degradation of the light source and components occurs in high-illuminance environments
Solution Approach 1:
The control start temperature is made dynamic rather than fixed, adjusting based on ambient illuminance conditions. The control ECU sets a lower control start temperature when illuminance exceeds a threshold value, and a higher control start temperature when illuminance is below the threshold, allowing the system to adapt to different environmental conditions
Solution Approach 2:
The system changes the temperature parameter (control start temperature) based on another parameter (illuminance level). By monitoring ambient illuminance and adjusting the control start temperature accordingly, the system optimizes both thermal protection and luminous flux maintenance for different operating environments
2Reliability
If derating control is initiated early to suppress thermal degradation, then component reliability improves, but luminous flux and forward field of view are adversely affected
Solution Approach 1:
The system applies different control strategies to different operating conditions. By distinguishing between high-illuminance and low-illuminance environments, the control ECU applies appropriate control start temperatures locally suited to each condition, rather than using a uniform approach
Solution Approach 2:
The system uses feedback from illuminance sensors to continuously monitor environmental conditions and adjust the control start temperature accordingly. This closed-loop control ensures that derating is applied appropriately based on actual thermal stress conditions
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 system effectively suppresses thermal degradation of the light source and its components by initiating derating control earlier in severe environments, maintaining luminous flux and avoiding adverse effects on the forward field of view while reducing additional costs through the use of existing vehicle sensors.
Implementation Method 1
a temperature sensor that measures a temperature of the light source or surroundings of the light source
Implementation Method 2
a light source that emits light due to a drive current that is supplied from a light source drive circuit
Data Source
AI summary
A vehicle lamp that includes: a light source that emits light due to a drive current that is supplied from a light source drive circuit; and a temperature sensor that measures a temperature of the light source or surroundings of the light source, wherein the light source drive circuit reduces the drive current when the temperature that has been measured by the temperature sensor becomes equal to or greater than a control start temperature, and, in a case in which an illuminance of surroundings of a vehicle that has been measured by an illuminance measurement sensor is equal to or greater than an illuminance threshold, the control start temperature is set to be lower than in a case in which the illuminance of the surroundings of the vehicle is less than the illuminance threshold.