Slanted Glass Cover Structure for Image Sensor Stray Light
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Digital image sensor packages face noise issues due to stray light reflecting off the glass covering, which current solutions like photoabsorbent materials are either ineffective or incompatible with all layouts and can be unreliable.
Innovation Solution
A glass covering with a trapezoidal cross-section is attached directly to the image sensor, featuring an obtuse angle between the sidewall and bottom surface to deflect incoming light away from the sensor, optimized for specific field of view and lighting conditions, and secured with a transparent adhesive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a glass covering with vertical sidewalls is used, then the structure is simple and easy to manufacture, but stray light reflects off the sidewall and causes noise in the captured image
Solution Approach 1:
The glass covering sidewalls are designed with a specific slant angle (45 degrees) relative to the vertical direction, creating an asymmetric structure that redirects stray light away from the image sensor. This asymmetric geometry transforms the harmful reflection path into a beneficial light redirection, solving the stray light problem while maintaining manufacturing simplicity.
2Object-affected harmful factors
If photoabsorbent material is added to absorb stray light, then stray light noise is reduced, but the manufacturing process becomes more complex and the material may become detached
Solution Approach 1:
The patent removes the photoabsorbent material from the system entirely and replaces it with a geometric solution. By extracting the harmful element (vertical sidewalls that cause reflection) and replacing it with a slanted geometry, the patent eliminates the need for additional absorptive materials and their associated manufacturing complexity and reliability issues.
Solution Approach 2:
Instead of trying to absorb or block stray light with additional materials, the patent converts the reflection phenomenon into a beneficial effect. The slanted sidewalls are designed to redirect stray light away from the sensor at specific angles, transforming the harmful reflection into a useful light management mechanism that naturally prevents stray light from reaching the image sensor.
3Volume of moving object
If the glass covering is positioned closer to the image sensor, then the overall package size is reduced, but light transmission may be interfered with
Solution Approach 1:
The glass covering is designed with different properties at different locations: the bottom surface is flat for optimal light transmission, while the sidewalls are slanted at 45 degrees for stray light redirection. This local differentiation of geometric properties allows the glass covering to simultaneously achieve good light transmission and effective stray light management, even when positioned close to the image sensor.
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 design effectively reduces noise in captured images by directing stray light away from photodiodes, eliminating the need for photoabsorbent materials and ensuring stability and optical clarity.
Implementation Method 1
any incoming light that reflects off the sidewall of the glass 15 on a path leading it to strike the photodiodes 13
Implementation Method 2
A transparent adhesive layer 14 physically couples a glass covering 15 over the image sensor substrate 12
Data Source
AI summary
Disclosed herein is a method of reducing noise captured by an image sensor. The method includes affixing a bottom surface of a glass covering to the image sensor, permitting light to impinge upon the glass covering, and shaping the glass covering such that when the light that impinges upon the glass covering impinges upon a sidewall of the glass covering, the sidewall reflects the light on a trajectory away from the image sensor.