Automotive Lighting Circuit Segmentation for Cost Reduction
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Solution Overview
Problem
The high-cost issue associated with designing lighting circuits for automotive lamps with a large number of channels, particularly due to the need for high-breakdown-voltage ICs and constant current converters that support wide output voltage ranges, is exacerbated by the difficulty in maintaining stability over such ranges.
Innovation Solution
A lighting circuit configuration that groups light-emitting elements into control units with duty ratios summing to 100% or less, allowing reduced voltage drops and breakdown voltages, and pairs bypass switches to prevent simultaneous activation, thereby reducing the overall circuit costs and output voltage range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of light-emitting elements is increased to support high-resolution ADB control, then the light distribution control precision is improved, but the breakdown voltage requirement and circuit cost increase
Solution Approach 1:
The light-emitting elements are divided into multiple groups, with each group containing a subset of the total elements. Each group is controlled independently by its own constant current converter and bypass switch circuit. This segmentation allows each circuit module to handle fewer elements, reducing the breakdown voltage requirement and cost for each module while maintaining overall high-resolution control capability across all groups.
2Adaptability or versatility
If high-breakdown-voltage ICs are used to support a large number of series-connected light-emitting elements, then the light distribution control capability is improved, but the device complexity and cost increase
Solution Approach 1:
The bypass switch circuit is divided into multiple independent units, each corresponding to a specific group of light-emitting elements. Each bypass switch unit has a lower breakdown voltage requirement compared to a single unified bypass switch for all elements. This segmentation reduces device complexity by using multiple simpler components instead of one complex high-voltage component.
3Adaptability or versatility
If the output voltage range of the constant current converter is widened to accommodate all light-emitting elements, then the light distribution flexibility is improved, but the stability and cost worsen
Solution Approach 1:
The constant current converter is implemented as multiple independent units, each responsible for a specific group of light-emitting elements. Each converter operates within a limited output voltage range corresponding to its group, ensuring stable operation. This segmentation maintains overall system flexibility while improving stability by avoiding the need for each converter to handle the full voltage range of all elements.
4Ease of operation
If multiple bypass switches are controlled independently without coordination, then the control simplicity is improved, but the heat generation and energy loss increase
Solution Approach 1:
Multiple bypass switches are coordinated through a control unit that manages their operation collectively. The control unit ensures that bypass switches are activated in a coordinated manner, reducing simultaneous conduction losses and heat generation. This merging of control logic maintains operational simplicity while reducing energy loss compared to completely independent control.
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 configuration reduces the maximum output voltage and breakdown voltage requirements, lowering costs and maintaining circuit stability, while allowing for efficient light distribution control with reduced heat generation and adaptable light distribution patterns.
Implementation Method 1
Each light-emitting element 3 is configured as a semiconductor device such as an LED (light-emitting diode)
Implementation Method 2
The light source 2 includes multiple light-emitting elements 3
Data Source
AI summary
A lighting circuit drives a light source including N (N represents an integer of 2 or more) multiple light-emitting elements coupled in series. A bypass switch circuit includes N multiple bypass switches, each coupled in parallel to a corresponding light-emitting element. A constant current driving circuit supplies a driving current stabilized to a target current to the light source. A light distribution controller controls the bypass switch circuit. For a given light distribution pattern, the duty ratio Di(%) is determined for each of the N multiple light-emitting elements. Multiple light-emitting elements are formed as control units having a sum total of duty ratios that is less than 100%. The light distribution controller controls the multiple bypass switches such that the multiple light-emitting elements included in the same control unit are not turned on at the same time.