940nm LED Flash Synchronization for DMS and OMS Interference
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Solution Overview
Problem
The interference between 940 nm LED light sources used in driver monitoring systems (DMS) and occupant monitoring systems (OMS) leads to vision algorithm failures, requiring careful arrangement of LED units to avoid interference, which is inconvenient and sometimes impossible.
Innovation Solution
A control circuit synchronizes the 940 nm LED flashes between DMS and OMS cameras, using a monochrome global shutter CMOS sensor and an RGBIR rolling shutter CMOS sensor, to prevent interference and allow for flexible placement of the units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If 940 nm LED light sources are used in both DMS and OMS, then the monitoring systems can operate with the same light source wavelength for consistency, but the LED units interfere with each other causing vision algorithm failure
Solution Approach 1:
The patent implements periodic flash synchronization where the DMS and OMS LED flashes are coordinated in time. The control circuit generates flash control signals that periodically activate LED units in a synchronized manner, ensuring that both systems use 940 nm light sources while avoiding simultaneous emission that would cause interference and algorithm failure.
2Reliability
If LED units are arranged to point in different directions to avoid interference, then interference is reduced, but the installation becomes complex and sometimes impossible
Solution Approach 1:
The control circuit performs preliminary coordination of flash timing before the actual monitoring operation. By pre-synchronizing the flash cycles of DMS and OMS LED units, the system eliminates the need for complex physical arrangement of LED directions, making installation simple while maintaining reliability.
3Use of energy by moving object
If LED flashes are synchronized with camera shutter time, then average power is reduced for human vision health and thermal considerations, but precise timing control is required
Solution Approach 1:
The control circuit merges the flash control functions of both DMS and OMS into a single coordinated system. By combining the timing control logic, the patent achieves low average power consumption through synchronized flashing while managing the complexity centrally rather than requiring separate complex timing mechanisms for each system.
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
The synchronization of LED flashes eliminates interference, enabling convenient installation and improving the reliability of monitoring systems by reducing the need for specific directional alignment of LED units.
Implementation Method 1
The LED flash needs to be synchronized with a shutter time of the DMS camera... The OMS uses a rolling shutter RGBIR sensor with a LED light source. A 940 nanometer (nm) LED light source is preferred because 850 nm light is visible for humans.
Implementation Method 2
The driver monitoring system generally includes a camera directed toward the driver's face... The occupant monitoring system generally includes one or more cameras directed toward passengers
Data Source
AI summary
An apparatus includes a first image sensor, a second image sensor, a first light source associated with the first image sensor, a second light source associated with the second image sensor, and a control circuit. The control circuit may be configured to control the first light source and the second light source to prevent interference between the first and the second light sources affecting images captured by the first and the second image sensors.