Inner Mirror Camera Layout to Minimize Ghost Images
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Solution Overview
Problem
In inner mirrors with built-in cameras, the optical axis of the infrared camera is often tilted relative to the normal direction of the mirror element, leading to a ghost image caused by the internal structure when strong external light enters, which reduces visibility and recognition accuracy of the captured image.
Innovation Solution
The infrared camera's optical axis is tilted relative to the normal direction of the mirror element by using a back plate with a recessed surface portion and a flat surface portion, where the lens exposure opening is inclined, minimizing the step between the lens and the back plate without increasing the mirror's thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical axis of the infrared camera is tilted relative to the normal direction of the mirror element, then the camera can capture objects at the center position of the field of view, but a ghost image is caused by the internal structure when strong external light enters, reducing visibility and recognition accuracy
Solution Approach 1:
The patent introduces a new dimensional approach by creating a recessed surface portion that forms an inclined surface. This inclined surface allows the lens exposure opening to be positioned at an angle relative to the back plate, enabling the optical axis to be tilted while managing the ghost image issue through a three-dimensional structural solution rather than a simple planar adjustment.
Solution Approach 2:
The back plate is designed with different surface qualities in different regions: a flat surface portion and a recessed surface portion with an inclined surface. This local differentiation allows the lens exposure opening to have a specific tilted orientation while maintaining overall structural integrity and controlling light paths to minimize ghost images.
2Ease of operation
If the optical axis is tilted by positioning the lens at an angle, then the camera can monitor the driver or rear seat at the center position, but the step between the lens and the back plate becomes larger, making the ghost image more conspicuous
Solution Approach 1:
Instead of creating a large step by简单地 tilting the lens on a flat surface, the patent uses a recessed surface portion that provides a controlled inclined surface. This approach allows the lens to be positioned at the required angle while the recessed structure manages the step height, preventing it from becoming excessively large and conspicuous.
3Device complexity
If the substrate is tilted to accommodate the tilted optical axis, then the step between lens and substrate is reduced, but the dimension of the inner mirror in the front-back direction becomes larger
Solution Approach 1:
The back plate is segmented into two distinct surface portions: a flat surface portion and a recessed surface portion. This segmentation allows the lens exposure opening to be positioned in the recessed portion with an inclined surface, accommodating the tilted optical axis without requiring the entire back plate to be tilted, thus controlling the overall thickness of the inner mirror.
4Object-affected harmful factors
If a light-shielding member is disposed between the infrared lighting device and the lens, then flare is prevented, but when the substrate is tilted, a gap between the mirror element and substrate expands, making it difficult for the light-shielding member to block infrared light
Solution Approach 1:
Instead of trying to expand the light-shielding member to cover larger gaps caused by tilting, the patent inverts the approach by creating a recessed surface portion that naturally accommodates the tilted lens position. This recessed structure maintains consistent spacing between the mirror element and the lens area, ensuring the light-shielding member remains effective without requiring excessive expansion.
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
This configuration reduces the visibility of ghost images and improves the recognition accuracy of the captured image by minimizing the step between the lens and the back plate, while maintaining a compact design and preventing dirt entry.
Implementation Method 1
a mirror element 26 that reflects visible light and transmits infrared light
Implementation Method 2
a mirror element 26 that reflects visible light and transmits infrared light
Data Source
AI summary
To make a ghost image that is caused by a step place between a lens and a back plate inconspicuous in a configuration in which an optical axis of an infrared camera is disposed tilted relative to a normal direction of a plate face of a mirror element. A flat surface portion and a recessed surface portion are formed on the back plate disposed behind the mirror element. At least a part of a lens exposure opening is formed in an inclined surface of the recessed surface portion, the inclined surface being inclined relative to the flat surface portion. The lens of the infrared camera is disposed on the inclined surface with the optical axis titled relative to the normal direction of the flat surface portion, following the lens exposure opening.