Vehicle Lighting Circuit Mode Control via Dual Signal Encoding
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Solution Overview
Problem
Vehicle lighting devices with high-luminance light sources face challenges in managing multiple lighting modes with a limited number of control signals, requiring increased safety and reliability, especially in preventing abnormal conditions like short-circuits that can prevent the light source from being extinguished.
Innovation Solution
A lighting circuit that uses two control signals to select among multiple modes, employing non-pulse signals for extinguishing and pulse signals with varying duty ratios to control the light source unit, ensuring fail-safe operation and mode switching with reduced wire complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of lighting modes or operational states is increased to enhance vehicle lighting device functionality, then the lighting device can provide more functions (such as additional high beam, road surface marking), but the number of control signals and wires increases
Solution Approach 1:
The patent combines multiple control functions into a single control signal by encoding mode information and operational state information together. The control signal includes a mode designation period that identifies the lighting mode (low beam, high beam, additional high beam, road surface marking) and an operational state designation period that specifies the operational state within that mode. This merging approach allows the lighting device to support multiple lighting modes and operational states while using only one control signal, thereby reducing wire complexity while maintaining high adaptability.
2Ease of operation
If separate control signals are prepared for each mode with HIGH and LOW assigned to ON and OFF, then the control logic is simple, but the fail-safe function is reduced when a control line is short-circuited with an electric power source
Solution Approach 1:
The patent introduces a control signal processing unit that acts as an intermediary between the control signal and the light source driving unit. This processing unit decodes the control signal to extract both mode designation information and operational state designation information. By using this intermediary decoding approach, the system maintains simple control logic while enhancing reliability through the ability to properly interpret and respond to control signals even in abnormal conditions, as the decoding process can detect and handle short-circuit conditions appropriately.
3Device complexity
If a single control signal is used to reduce wire complexity, then the number of wires is reduced, but it becomes difficult to provide both mode information and operational state information simultaneously
Solution Approach 1:
The patent segments the control signal into distinct time periods: a mode designation period and an operational state designation period. During the mode designation period, the control signal carries information about which lighting mode should be activated. During the operational state designation period, the control signal carries information about the specific operational state within that mode. This temporal segmentation allows a single control signal to convey multiple pieces of information without confusion, maintaining complete control information while using minimal wiring.
Data Source
AI summary
A lighting circuit includes a control unit that selects one of an extinguishing mode and a plurality of lighting modes based on a first control signal and a second control signal, and a drive unit. The control unit is configured to i) select the extinguishing mode when at least one of the first control signal and the second control signal is a non-pulse signal, and ii) select one of the plurality of lighting modes based on the combination of the duty ratio of the first control signal and the duty ratio of the second control signal, when both the first control signal and the second control signal are pulse signals.