Rearview Display Mirror With Variable Reflectance for Headlight Glare
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Solution Overview
Problem
Existing display systems for vehicles that capture and display images rearward of the vehicle face issues with visual recognition due to fluctuations in brightness and glare from headlights, leading to difficulties for drivers in viewing images effectively, especially when anti-glare technology interferes with video display.
Innovation Solution
A display system with an image capture device, a display device, a first illuminance sensor, and a second illuminance sensor, featuring an electro-optic layer with a transmissive-reflective layer that adjusts reflectivity and brightness control, allowing the driver to switch between viewing rearward images on the display or a mirror image, and controlling brightness based on detected light intensities to reduce glare.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the display device uses a fixed reflective layer to display rearward images, then the driver can view the images, but glare from headlights reduces visual recognition
Solution Approach 1:
The patent applies a variable reflectivity layer (electro-optic layer) that can dynamically change its optical properties. The control circuit adjusts the reflectivity of this layer based on detected light conditions to adapt between displaying rearward images and showing mirror reflections, thereby resolving the contradiction between image visibility and glare reduction
Solution Approach 2:
The patent changes the optical parameters of the reflective layer by using an electro-optic layer whose reflectivity can be varied electrically. The control circuit modifies the reflectivity parameter in response to illuminance sensor data, enabling the layer to transition between high reflectivity (for mirror mode) and low reflectivity (for image display mode), thus solving the glare problem while maintaining image visibility
2Illumination intensity
If the display device increases brightness to improve image visibility, then the driver can see rearward images better, but glare from external light sources increases
Solution Approach 1:
The patent converts the harmful effect of external light (glare) into a useful signal by using illuminance sensors to detect the intensity and direction of incoming light. The control circuit then uses this information to adjust the electro-optic layer's reflectivity, transforming the glare problem into a control parameter that optimizes both image visibility and glare reduction
Solution Approach 2:
The patent implements a feedback control system where illuminance sensors continuously monitor the light environment, and the control circuit adjusts the electro-optic layer's reflectivity based on this feedback. This closed-loop control enables the system to maintain optimal image visibility while automatically compensating for varying glare conditions from external light sources
3Adaptability or versatility
If the display device uses a transmissive-reflective layer to switch between image display and mirror reflection, then the driver can choose viewing modes, but the switching mechanism increases device complexity
Solution Approach 1:
The patent uses a single electro-optic layer that serves multiple functions: it can display rearward images when reflectivity is reduced, and it can function as a traditional mirror when reflectivity is increased. This multi-functional component replaces what would otherwise require separate display and mirror systems, achieving versatility without proportionally increasing complexity
Solution Approach 2:
The electro-optic layer acts as an intermediary between the light source (rearward scene) and the driver's eye. By controlling the optical properties of this intermediate layer, the system can selectively transmit or reflect light to achieve different viewing modes, simplifying the overall control mechanism compared to having separate systems for each function
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
Improves visual recognition of rearward images by adjusting brightness and reflectivity, minimizing glare from headlights, thereby enhancing the driver's ability to view images or mirror images without interference.
Implementation Method 1
an electro-optic layer with a transmissive-reflective layer that transmits a portion of incident light and reflects another portion of the incident light, the electro-optic layer being configured to vary reflectivity of the incident light
Implementation Method 2
a first illuminance sensor that detects brightness around the vehicle, and a second illuminance sensor that detects intensity of light emitted onto a front surface of the display device
Data Source
AI summary
A display device includes a housing, a variable reflectance element, a display to display at least a portion of a rearward image, a display device control circuit, and an actuator to switch the variable reflectance element between first and second postures. In the first posture, the display displays the portion of the rearward image. In the second posture, the display displays the rearward image. In the second posture, the reflectivity of the incident light varies between first and second values of a first and a second illuminance, respectively. The first illuminance indicates brightness around a vehicle and is detected by a sensor. The second illuminance indicates intensity of light emitted on a front surface of the display device and is detected by another sensor. When the display displays at least the portion of the rearward image, the display is visible to a driver through the variable reflectance element.