Vehicle Light Assembly With Low-Side Switching for Fail-Safe Beam Control
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Solution Overview
Problem
Existing vehicle headlamp light assemblies face safety issues due to the inability to deactivate the high beam function without also deactivating the low beam function when a switch fails, requiring complex additional circuits for control.
Innovation Solution
A light assembly design with a first switching unit in low side position between the high beam and low beam modules, allowing for simplified control and the addition of a fourth switching unit to prevent activation of the high beam when the second switching unit is open, along with a third lighting module for additional functions, enabling independent control of multiple lighting functions using a single driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a switch is mounted in parallel to the HB module in high side position, then the HB function can be deactivated, but a complex additional circuit is required to control the switch opening and closing
Solution Approach 1:
The patent inverts the switching strategy by placing the first switching unit in low side position (between LB module and ground) rather than high side position (between driver and LB module). This inversion allows direct control of the N-MOS transistor without requiring complex additional circuits to provide gate-source voltage, thereby reducing circuit complexity while maintaining reliable control
Solution Approach 2:
The patent introduces a second switching unit connected in parallel to the HB module as an intermediary element. This second switching unit works in coordination with the first switching unit to provide fail-safe control: when the first switching unit fails open, the second switching unit ensures HB deactivation. This intermediary approach resolves the contradiction by distributing control functions across multiple simpler switching units rather than requiring one complex switching circuit
2Reliability
If a switch is mounted in parallel to the HB module, then the HB function can be deactivated, but the LB function cannot be deactivated without also deactivating the HB function when switch fail status occurs
Solution Approach 1:
The patent segments the control function into two independent switching units: the first switching unit (in low side position) controls the LB module, and the second switching unit (in parallel to HB module) controls the HB module. This segmentation allows independent control of each lighting function, resolving the contradiction where a single switch could not independently control HB and LB functions. Each switching unit can fail independently without affecting the other function's controllability
Solution Approach 2:
The patent implements fail-safe control by positioning the first switching unit in low side configuration, which inherently provides a safe default state (LB off when switch fails open). Additionally, the second switching unit is configured to detect when the first switching unit fails and automatically ensure HB deactivation. This beforehand cushioning approach prevents the contradiction by designing the system to anticipate and handle switch failure scenarios before they compromise safety or control
Data Source
AI summary
A light assembly including a first lighting module for performing a low beam function, and a second lighting module for performing a high beam function and a driver. The light assembly includes a first switching unit connected in series with the first and second lighting modules and controlled by a first control unit, and a second switching unit connected in parallel to the second lighting module and controlled by a second control unit. The first switching unit is connected in low side position between the second lighting module and the ground.