Slanted Glass Cover Edge for Image Sensor Stray Light Control
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Solution Overview
Problem
Digital image sensor packages face noise issues due to stray light reflecting off the sidewall of the glass covering, which current designs attempt to mitigate with photoabsorbent materials that add complexity and are unreliable.
Innovation Solution
A glass covering with a trapezoidal cross-section is used, where the top surface has a greater surface area than the bottom surface, forming acute and obtuse angles with the sidewall, causing reflected light to be directed away from the image sensor, eliminating the need for photoabsorbent materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If photoabsorbent material is placed at the edge of the glass to absorb stray light, then noise in the captured image is reduced, but the device complexity increases and reliability decreases due to additional manufacturing steps and potential material detachment
Solution Approach 1:
The glass covering is designed with an asymmetric cross-sectional shape where the top surface has a greater surface area than the bottom surface. This asymmetry causes the sidewall to be anti-perpendicular to the top and bottom surfaces, creating different angles that redirect stray light away from the photodiodes. This geometric asymmetry eliminates the need for additional photoabsorbent materials while maintaining the noise reduction function.
Solution Approach 2:
Instead of adding material to absorb stray light (the conventional approach), the invention inverts the approach by using the glass covering's own geometry to redirect stray light away from the photodiodes. The anti-perpendicular sidewall design causes reflected light to follow trajectories that avoid the image sensor, turning the glass covering into an active stray light management component rather than just a protective cover.
2Object-affected harmful factors
If photoabsorbent material is placed at the edge of the glass to absorb stray light, then noise in the captured image is reduced, but the reliability decreases as the photoabsorbent material may become detached
Solution Approach 1:
The invention extracts the stray light absorption function from a separate photoabsorbent material layer and integrates it directly into the glass covering structure itself. By designing the glass covering with an anti-perpendicular sidewall geometry, the glass covering itself performs the stray light redirection function, eliminating the need for separate photoabsorbent materials that could detach and improving overall system reliability.
Solution Approach 2:
The invention merges the stray light management function with the glass covering structure. The glass covering simultaneously serves as a protective cover and as an active component that redirects stray light through its anti-perpendicular sidewall geometry. This consolidation eliminates potential detachment issues between separate materials while maintaining both protective and optical management functions.
3Ease of manufacture
If a glass covering with equal top and bottom surface areas is used, then the manufacturing process is simple, but stray light reflects off the sidewall onto the photodiodes causing noise
Solution Approach 1:
The glass covering is designed with an asymmetric cross-sectional shape where the top surface has a greater surface area than the bottom surface. This asymmetry causes the sidewall to be anti-perpendicular to the top and bottom surfaces, creating different angles that redirect stray light away from the photodiodes. This geometric asymmetry eliminates the need for additional photoabsorbent materials while maintaining the noise reduction 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
This design effectively reduces noise in image capture by redirecting stray light, improving image quality without the need for additional photoabsorbent materials and simplifying the manufacturing process.
Implementation Method 1
some incoming light IL may arrive along a path whereby it enters the top side of the glass 15, then reflects off the sidewall of the glass 15 on a path leading it to strike the photodiodes 13
Data Source
AI summary
A digital image sensor package includes an image sensor substrate and a glass covering. The image sensor substrate carries photodiodes. The glass covering has a bottom surface, a top surface opposite the bottom surface, and a sidewall delimiting a perimeter edge of the glass covering. The glass covering overlies the photodiodes. A surface area of the top surface of the glass covering is greater than a surface area of the bottom surface of the glass covering such that the sidewall is anti-perpendicular to the top and bottom surfaces of the glass.