Dual-Branch Sensor Circuit for Interference-Free LED Communication
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Solution Overview
Problem
The integration of a light source in vehicle door handles poses a challenge due to interference with communication between capacitive detection sensors and the Body Control Module (BCM) when current inrushes for lighting coincide with communication signals, necessitating additional wiring that complicates integration and increases costs.
Innovation Solution
A method and device that utilize a circuit with two parallel branches to manage light source activation and communication on the same supply line, modulating current intensity to distinguish between light source control and communication signals, allowing concurrent operation without interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light source is integrated into the door handle, then user comfort and aesthetics are improved, but communication between the sensor and BCM is interfered with due to current inrush conflicts
Solution Approach 1:
The patent applies periodic action by using pulse-width modulation (PWM) to control the light source at a frequency above human perception (e.g., 200 Hz), creating periodic on-off cycles that provide illumination while enabling communication during the off periods. This periodic operation allows the system to alternate between lighting and communication functions on the same supply line without interference.
Solution Approach 2:
The patent implements dynamics by making the duty cycle of the PWM signal adjustable based on operational mode. During communication events, the duty cycle is reduced to create larger current variations for reliable signal detection. During normal illumination, the duty cycle increases to provide adequate lighting. This dynamic adjustment allows the system to optimize performance for different functions.
2Reliability
If additional wiring is added to separate light control and communication signals, then communication reliability is improved, but device complexity and integration difficulty increase
Solution Approach 1:
The patent merges the light source control and communication signal transmission functions into a single supply line. By using PWM modulation, the same electrical connection serves dual purposes: providing power to the light source and carrying communication signals through current variations. This eliminates the need for separate wiring and reduces integration complexity while maintaining communication reliability.
Solution Approach 2:
The supply line is designed to be universal, serving multiple functions simultaneously. It provides both power delivery for the light source and a communication channel for sensor-to-BCM signaling. The BCM's ability to detect current variations allows it to distinguish between power delivery and communication events, enabling one wire to perform multiple roles without compromising either function.
3Illumination intensity
If current intensity is increased for light source activation, then illumination quality is improved, but communication signal detection becomes difficult due to signal masking
Solution Approach 1:
The patent uses periodic PWM control to create distinct time windows for illumination and communication. During the off-period of the PWM cycle, the light source current is zero or minimal, creating a clear baseline for detecting communication signal current variations. This periodic separation ensures that high illumination current during the on-period does not mask communication signals, as communication events are detected during the off-period when current variations are most detectable.
Data Source
AI summary
Method for communication between an electronic module and a sensor having a first branch, including a light source LED and a first switch, and a second branch including a second switch, supplied by a supply line, the module measuring modulations of intensity of current of the line. When the light source is turned on or in the process of turning on/turning off, the sensor causes i) modulation of the intensity of the current in the LED between a high state and a low state, ii) modulation of the intensity of the current in the second branch so that the intensity of the current is always in a higher state, and, in case of detection, iii) dispatches to the electronic module a modulation of the intensity of current in the second branch, when the intensity of current in the LED is in the low state.