Image Sensor Autofocusing via Distinct Microlens Focal Lengths
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Solution Overview
Problem
Current image sensors face challenges in achieving accurate autofocusing due to the similarity in focal lengths of image pixels and phase difference detection pixels, which affects their performance in various applications.
Innovation Solution
The design of an image sensor with distinct focal lengths for image pixels and phase difference detection pixels, achieved through the use of different microlenses in specific regions, allows for improved autofocusing accuracy by separating the focal lengths of the first and second microlenses in the image detection and phase difference detection regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the same microlens is used for both image pixels and phase difference detection pixels, then the manufacturing process is simplified, but the autofocusing accuracy deteriorates due to identical focal lengths
Solution Approach 1:
The patent applies local quality by configuring different microlenses with different focal lengths in different regions of the image sensor. Specifically, a first microlens with a first focal length is used for image pixels, while a second microlens with a second focal length is used for phase difference detection pixels. This allows each region to have optimized optical properties for its specific function, resolving the contradiction between manufacturing simplicity and autofocusing accuracy.
2Measurement precision
If different microlenses with different focal lengths are used for image pixels and phase difference detection pixels, then the autofocusing accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the image sensor into distinct regions with different microlens configurations. The image sensor is segmented into a first region with image pixels using a first microlens and a second region with phase difference detection pixels using a second microlens. This segmentation allows for optimized performance in each region while maintaining overall system functionality, addressing the complexity issue through functional分区.
3Speed
If a hybrid autofocus method is implemented using part of the image sensor, then the focus detection speed is improved, but the autofocusing accuracy deteriorates due to focal length similarity
Solution Approach 1:
The patent applies parameter changes by modifying the focal length parameter of the microlenses used in different regions. The first microlens for image pixels has a first focal length, while the second microlens for phase difference detection pixels has a second focal length that is different from the first. This parameter differentiation enables the hybrid autofocus method to achieve both fast focus detection speed and high accuracy by allowing the phase difference detection pixels to generate accurate phase difference information despite the speed requirements.
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 enhances the accuracy of autofocusing by ensuring that image pixels and phase difference detection pixels have different focal lengths, thereby improving the overall performance of the image sensor in capturing and focusing images.
Implementation Method 1
a plurality of first microlenses selectively disposed on bottom surfaces of the plurality of groove portions corresponding to at least one of the first region and the second region, and a plurality of second microlenses separated by the second grid pattern, the plurality of second microlenses being disposed on the plurality of color filters, respectively
Implementation Method 2
a plurality of color filters filling the plurality of groove portions, respectively
Implementation Method 3
a plurality of pixel regions spaced apart from each other, the plurality of pixel regions including a first region including a plurality of image pixels configured to generate image data and a second region including a plurality of phase difference detection pixels configured to perform autofocusing
Data Source
AI summary
Provided is an image sensor including a semiconductor substrate including a first surface and a second surface and a plurality of pixel regions spaced apart, the plurality of pixel regions including a first region including a plurality of image pixels configured to generate image data and a second region including a plurality of phase difference detection pixels configured to perform autofocusing, a first grid pattern including a plurality of groove portions disposed on the second surface, a plurality of first microlenses selectively disposed on bottom surfaces of the plurality of groove portions corresponding to at least one of the first region and the second region, a plurality of color filters filling the plurality of groove portions, respectively, a second grid pattern superimposed on the first grid pattern, and a plurality of second microlenses separated by the second grid pattern and disposed on the plurality of color filters, respectively.