Camera Module Aperture Coating for Stray Light and Relative Illuminance
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Solution Overview
Problem
Conventional camera modules suffer from defects in the light-blocking layer, such as uneven coating, insufficient optical density, and stray light generation, which affect optical quality and relative illuminance, especially in low-light conditions.
Innovation Solution
A camera module with a light-blocking layer on a plastic optical element, featuring a specific shape and optical density distribution, including a main portion and a compensation portion, to ensure precise light shielding and reduce stray light, with conditions such as −LOG(RI)/DM≤1.2, 3 degrees≤tan−1(T/L)≤89.5 degrees, and 0.7 μm−1≤DM/T≤7.2 μm−1, to enhance optical quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If excessive shading is used from the light-blocking layer to achieve light-shielding effect, then light blocking capability is improved, but optical quality of peripheral region is sacrificed and relative illuminance is reduced
Solution Approach 1:
The light-blocking layer is designed with spatially varying optical density, where the peripheral region has lower optical density than the central region. This local differentiation allows the peripheral area to transmit more light (improving relative illuminance) while the central area maintains strong light blocking capability, thus resolving the contradiction between light shielding and peripheral illuminance.
2Manufacturing precision
If the light-blocking layer is made thinner to improve uniformity, then manufacturing uniformity is improved, but optical density becomes insufficient and light passes through causing noise
Solution Approach 1:
Instead of uniformly thinning the light-blocking layer, the patent changes the optical density parameter spatially across the layer. The peripheral region is designed with lower optical density (allowing light transmission) while the central region maintains higher optical density (blocking light), thus achieving both uniform manufacturability and sufficient light blocking performance without compromising either requirement.
3Object-affected harmful factors
If the light-blocking layer is made thicker to improve light shielding, then optical density is improved, but manufacturing precision deteriorates due to coating difficulty and uniformity loss
Solution Approach 1:
The light-blocking layer employs local quality differentiation where different regions have different thicknesses and optical densities. The peripheral region is thinner with lower optical density, while the central region is thicker with higher optical density. This local variation simplifies the coating process requirements compared to a uniformly thick layer, as it reduces the stress and uniformity challenges associated with depositing thick coatings across the entire surface.
4Reliability
If defects exist in the peripheral region of the light-blocking layer, then manufacturing reliability is reduced, but light shielding function is compromised and optical quality deteriorates
Solution Approach 1:
The patent designs the light-blocking layer with locally optimized properties where the peripheral region has lower optical density and reduced thickness requirements. This local differentiation means that even if defects occur in the peripheral region, they are less likely to cause light leakage compared to defects in a uniformly high-density layer, thus maintaining light shielding reliability while being more tolerant to manufacturing variations in the peripheral area.
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 solution improves optical quality by ensuring sufficient light shielding, reducing stray light, and maintaining uniform thickness, thereby enhancing the camera module's performance in various lighting conditions.
Implementation Method 1
a light-blocking layer is disposed on a transparent surface of the plastic optical element... an optical density of the compensation portion is lower than an optical density of the main portion... ensuring sufficient light shielding, reducing stray light
Data Source
AI summary
A camera module includes an imaging lens assembly and an image sensor. The imaging lens assembly includes a plastic optical element with a light-blocking layer disposed on its transparent surface. The plastic optical element includes an optical effective area, and a peripheral region of the light-blocking layer forms a specific shape around the optical effective area so as to define an aperture region. The peripheral region includes a main portion and a compensation portion. The main portion is physically contacted with the transparent surface. The compensation portion is disposed on an edge of the main portion adjacent to the optical effective area, and an optical density of the compensation portion is lower than an optical density of the main portion. The image sensor is disposed on an image side of the imaging lens assembly for defining a maximum image height and further defining a relative illumination.