Image Sensor Anti-Reflection Structure for Stray Light Control
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Solution Overview
Problem
Conventional imaging lens assemblies experience image quality degradation due to stray light reflection between components, which affects the image sensor's performance.
Innovation Solution
An image sensor design incorporating an anti-reflection coating with alternating high and low refractive index layers and an anti-reflection structure with ridge-like protrusions on the light transmitting element and micro lens layer, reducing stray light reflection by maintaining low reflectance across a wide range of wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the micro lens layer is directly disposed on the light transmitting element, then the structure is simple and compact, but stray light reflection is generated between the micro lens layer and light transmitting element which degrades image quality
Solution Approach 1:
An anti-reflection coating layer is introduced as an intermediary between the light transmitting element and micro lens layer. This coating layer with optimized refractive index reduces the reflection coefficient at the interface, allowing light to pass through more efficiently while maintaining the compact structure. The anti-reflection coating acts as a mediator that minimizes harmful reflections without requiring a gap between components.
Solution Approach 2:
The refractive index parameter of the interface between light transmitting element and micro lens layer is modified by applying an anti-reflection coating with specific refractive index properties. This parameter change reduces the impedance mismatch between materials, thereby minimizing reflection and improving light transmission while keeping the structure compact.
2Object-affected harmful factors
If an anti-reflection coating with multiple layers is applied, then stray light reflection is reduced and image quality is improved, but the manufacturing process becomes more complex
Solution Approach 1:
Instead of using complex multi-layer anti-reflection coatings with different materials, the invention optimizes the refractive index parameter of a single-layer coating to achieve effective anti-reflection performance. This simplifies the manufacturing process while still reducing stray light reflection significantly, balancing optical performance with ease of manufacture.
Solution Approach 2:
The anti-reflection coating is formed using composite material structures that combine materials with complementary properties to achieve the desired refractive index. This allows effective anti-reflection performance to be achieved with a single layer rather than multiple layers, simplifying the manufacturing process while maintaining optical effectiveness.
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 effectively minimizes stray light reflection, enhancing image quality and maintaining optical performance and reliability by balancing optical performance and structural stability.
Implementation Method 1
The anti-reflection coating is at least disposed on the upper surface of the light transmitting element, wherein the anti-reflection coating includes a plurality of high refractive index layers and a plurality of low refractive index layers, which is alternately stacked by the high refractive index layers and the low refractive index layers
Implementation Method 2
The anti-reflection structure is disposed on at least one of the lower surface of the light transmitting element and the micro lens layer. The anti-reflection structure includes a plurality of ridge-like protrusions which are non-directionally extended from a disposing surface
Implementation Method 3
The image sensor die includes a photoelectric conversion layer and a micro lens layer. The photoelectric conversion layer is for converting a light into an electronic signal
Implementation Method 4
The micro lens layer is disposed above the photoelectric conversion layer for converging the light onto the photoelectric conversion layer
Data Source
Figure 1A
Figure 1B~1C
Figure 1D~1E
AI summary
An image sensor includes an image sensor die, a light transmitting element, at least one anti-reflection coating and at least one anti-reflection structure. The image sensor die includes a photoelectric conversion layer and a micro lens layer. The micro lens layer is disposed above the photoelectric conversion layer for converging the light onto the photoelectric conversion layer. The light transmitting element is disposed above the micro lens layer, and a gap is formed between the light transmitting element and the micro lens layer, the light passes through the light transmitting element and then travels into the image sensor. The anti-reflection coating is at least disposed on an upper surface of the light transmitting element. The anti-reflection structure is disposed on at least one of a lower surface of the light transmitting element and the micro lens layer.