Vehicle Lamp Lighting Circuit for Simultaneous Light Shutdown
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Solution Overview
Problem
Existing lighting circuits for vehicle lamps, particularly turn signal lamps, face challenges in simultaneously turning off multiple light sources due to variations in switch characteristics and operation.
Innovation Solution
A lighting circuit configuration is introduced, featuring a first light source connected to a power line, a second light source connected in series to the first, and switches (NMOS transistors) strategically placed to allow simultaneous control and shutdown of all light sources through a control circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multiple switches are used to control each light source individually, then each light source can be controlled independently, but the light sources cannot be turned off simultaneously due to switch characteristic variations
Solution Approach 1:
The patent merges the control function by introducing a common switch (first switch) that controls the power supply to all light sources simultaneously. This switch is connected in the power line before the series connection of light sources, allowing unified control. The control circuit activates this common switch to turn off all light sources at the same time, eliminating the timing discrepancies caused by individual switch variations.
Solution Approach 2:
The first switch serves multiple functions: it acts as a common control switch for all light sources, providing both independent control capability (when combined with individual switches) and simultaneous shutdown capability. This multi-functional switch resolves the contradiction by enabling both individual control and synchronized operation.
2Adaptability or versatility
If switches are connected in parallel to each light source, then each light source can be controlled independently, but timing shifts occur during shutdown due to switch operation variations
Solution Approach 1:
The control circuit is designed to activate the first switch (common switch) before the individual switches (second, third, and fourth switches) during the shutdown sequence. This preliminary action ensures that the power supply to all light sources is cut off simultaneously at the beginning, preventing timing shifts. The individual switches then turn off sequentially after the common switch has already established simultaneous shutdown.
3Reliability
If a common switch is used to control all light sources, then simultaneous shutdown is achieved, but individual control capability is reduced
Solution Approach 1:
The control system is segmented into two levels: a common switch (first switch) for simultaneous control of all light sources, and individual switches (second, third, and fourth switches) for independent control of each light source. This segmentation allows the system to achieve both simultaneous shutdown (through the common switch) and individual control (through the individual switches) without compromising either function.
Data Source
AI summary
Provided is a lighting circuit capable of simultaneously turning off a plurality of light sources. A lighting circuit applied to a vehicle lamp including a plurality of light sources having a first light source connected to a power line and a second light source connected in series to the first light source and connected to a ground line, the lighting circuit including a first switch provided between the power line and the ground line, a second switch provided between a power-line-side node of the second light source and the ground line, and a control circuit that turns on or off each of the first and second light sources by controlling ON/OFF of each of a plurality of switches including the first and second switches.