Driver Monitoring Camera With Modulated NIR Against Sunlight Washout
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Solution Overview
Problem
Existing driver monitoring systems using in-cabin cameras struggle to accurately assess driver attentiveness in high ambient lighting conditions, such as sunny days, due to image washout from sunlight.
Innovation Solution
A driver monitoring system that employs a camera and a modulated near-infrared illumination source to distinguish the driver's image from ambient light, using a CMOS imaging array sensor and electronic filtering to process image data, thereby reducing image washout and enhancing attentiveness monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an in-cabin mounted camera is used to monitor driver attentiveness, then driver monitoring capability is provided, but image quality deteriorates due to washout in high ambient lighting conditions
Solution Approach 1:
The patent segments the lighting spectrum by using a near-infrared illumination source that operates in a spectral region distinct from visible sunlight. This allows the camera to capture driver imagery in the near-IR band while sunlight (primarily visible spectrum) does not cause washout, effectively separating the useful signal from the harmful ambient lighting.
Solution Approach 2:
The patent changes the operational parameters of the camera system by equipping it with a near-infrared sensitive sensor and pairing it with a near-IR illumination source. This parameter change (operating in near-IR instead of visible spectrum) allows the system to function reliably in high ambient visible lighting conditions where traditional visible-light cameras would fail.
2Adaptability or versatility
If ambient sunlight is present during daytime driving, then normal driving conditions are maintained, but driver monitoring accuracy decreases due to image washout
Solution Approach 1:
The patent adds a new dimensional aspect to the imaging system by utilizing the near-infrared spectral dimension rather than relying solely on the visible spectrum. This dimensional change allows the system to operate effectively in daytime conditions with sunlight, as the near-IR illumination is distinct from the visible sunlight that causes washout in traditional cameras.
3Measurement precision
If a modulated near-infrared illumination source is used, then image washout is reduced in bright sunlight, but device complexity increases
Solution Approach 1:
The patent merges the illumination source and camera sensor into an integrated near-infrared driver monitoring system. The modulated near-IR LED illumination source is combined with a near-IR sensitive CMOS sensor, creating a unified system that naturally rejects visible sunlight while capturing driver imagery. This integration reduces overall system complexity compared to attempting to modify a standard visible-light camera 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
Effectively monitors driver attentiveness by filtering out ambient light, allowing for accurate detection of the driver's head and eye movements even in bright sunlight conditions, thereby improving safety by reducing distractions and fatigue-related accidents.
Implementation Method 1
The light emitted by the illumination source may be in a near infrared (near IR) spectral region that is invisible to the human eye, and that is outside the visible spectral region present in insolation (solar radiation at a given area) and that is at a wavelength within the sensitivity of the camera. The camera may comprise a CMOS imaging array sensor (comprising multiple rows and columns of photosensing elements) that is sensitive within the near infrared spectral region.
Implementation Method 2
The illumination source modulates or codes the emitted light so that the system (via processing of image data captured by the camera) can process image data in accordance with the modulated light to avoid image washout that may otherwise occur in high ambient lighting conditions
Data Source
AI summary
A vehicular driver monitoring system includes a driver monitoring camera and an illumination source accommodated within a movable head of an interior rearview mirror assembly of a vehicle. The illumination source is electrically activatable to emit near-infrared (NIR) light that illuminates with near-infrared (NIR) light at least the eyes of a driver of the vehicle. Emission of near-infrared (NIR) light by the illumination source is modulated on/off at an illumination source modulation rate. The camera frame capture rate of the driver monitoring camera is bigger than the illumination source modulation rate of near-infrared (NIR) light emitted by the illumination source. Frames of image data are captured by the camera and are processed while the illumination source is on and is emitting near-infrared (NIR) light, and frames of image data are captured by the camera and are processed while the illumination source is off and is not emitting near-infrared (NIR) light.