Rearview Mirror Eye Tracking Through Glare-Blocking Reflectance
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Solution Overview
Problem
Existing vehicular driver monitoring systems face challenges in accurately monitoring a driver's eyes due to glare and reflections from glasses, particularly sunglasses, which obstruct the camera's view and impair the system's ability to determine attentiveness and gaze direction.
Innovation Solution
A vehicular interior rearview mirror assembly with a variable reflectance mirror reflective element that adjusts between daytime and nighttime modes, reducing visible light transmissivity while maintaining near infrared light transmissivity, and a near infrared light emitter to enhance eye tracking, thereby improving the system's ability to monitor the driver's eyes through glare and reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the variable reflectance mirror reflective element operates in daytime mode with high visible light transmissivity, then the driver can see clearly through the mirror, but visible light reflections from glasses obscure the driver's head region in camera images
Solution Approach 1:
The system dynamically changes the optical parameters of the mirror reflective element by switching between daytime and nighttime modes. In daytime mode, the mirror allows high visible light transmissivity for clear viewing. When eye monitoring is required, the system switches to nighttime mode which reduces visible light transmissivity to eliminate reflections from glasses, thereby improving camera accuracy in detecting the driver's eyes.
Solution Approach 2:
The mirror reflective element dynamically adjusts its reflectance properties based on operational requirements. The system transitions between different optical states (daytime/n nighttime modes) to optimize both driver visibility and camera monitoring capability, making the mirror adaptive to different functional demands.
2Measurement precision
If the variable reflectance mirror reflective element darkens to nighttime mode to reduce visible light reflections, then eye monitoring accuracy improves, but the driver's rearward view is dimmed
Solution Approach 1:
The system employs periodic or intermittent switching between daytime and nighttime modes rather than continuous darkening. The mirror operates in daytime mode for normal viewing and temporarily switches to nighttime mode only when eye monitoring is required, then returns to daytime mode. This periodic action allows the system to achieve accurate eye tracking while minimizing the impact on driver visibility.
3Device complexity
If a standard visible light camera is used for driver monitoring, then the system is simple, but glare and reflections from glasses obstruct the view of the driver's eyes
Solution Approach 1:
The system changes the wavelength parameter of the light used for monitoring by employing near-infrared light instead of visible light. The near-infrared light emitter emits light at wavelengths that do not reflect from conventional glasses, and the near-infrared camera sensor detects this light to capture images of the driver's eyes without glare or reflection interference.
Solution Approach 2:
The system replaces the standard visible light camera system with a near-infrared optical system. This substitution involves using near-infrared light emitters and near-infrared sensitive camera sensors to detect light in the infrared spectrum, which passes through most glasses without reflection, thereby eliminating the glare problem while maintaining system functionality.
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 system effectively reduces glare and reflections from glasses, allowing for more accurate monitoring of the driver's eyes by relying on near infrared light, enhancing the system's ability to determine attentiveness and gaze direction, even in daytime conditions.
Implementation Method 1
A near infrared light emitter is accommodated by the mirror head, and the near infrared light emitter moves together and in tandem with the mirror head
Implementation Method 2
The variable reflectance mirror reflective element is adjustable between operating in (i) a daytime mode, where the variable reflectance mirror reflective element has a first level of visible light transmissivity, and (ii) a nighttime mode, where the variable reflectance mirror reflective element has a second level of visible light transmissivity
Implementation Method 3
The ECU processes captured image data of visible light reflected from the driver's head region and near infrared light reflected from the driver's head region
Data Source
AI summary
A vehicular driver monitoring system includes a vehicular interior rearview mirror assembly having a mirror head that accommodates a variable reflectance mirror reflective element, a driver monitoring camera and a near infrared light emitter. When the near infrared light emitter is electrically operated to emit near infrared, the near infrared light emitter emits near infrared light that illuminates at least a driver head region. While the variable reflectance mirror reflective element is operating in a first mode, and responsive to determination that visible light reflecting off glasses worn by the driver is obscuring the camera's view of the eyes of the driver, the vehicular driver monitoring system controls the variable reflectance mirror reflective element to reduce visible light transmissivity through the variable reflectance mirror reflective element to reduce visible light reflections at the glasses worn by the driver as captured in the image data captured by the driver monitoring camera.