Image Sensor Large-Defocus Detection Pixel Pairs
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Solution Overview
Problem
The focal plane phase detection technique for image sensors faces challenges in achieving accurate focus detection, particularly when dealing with large defocus conditions, where the existing focus detection pixels are not optimized for varying exit pupil distances, leading to reduced accuracy.
Innovation Solution
The implementation of an image sensor with a combination of high-accuracy focus detection pixels and large-defocus detection pixels, where the latter has a smaller opening width and is arranged in a configuration that accounts for different exit pupil distances, enhancing sensitivity to defocus displacement and improving focus detection accuracy across various defocus levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional focus detection pixels are used, then normal image acquisition is maintained, but focus detection accuracy deteriorates under large defocus conditions
Solution Approach 1:
The image sensor is segmented into different pixel types: normal pixels for image acquisition and large-defocus detection pixels for focus detection. These pixels are arranged in alternating columns, allowing the system to specialize certain pixels for focus detection while maintaining normal imaging capabilities with other pixels.
Solution Approach 2:
Large-defocus detection pixels are designed with a smaller opening width compared to normal pixels, creating local quality differentiation. This smaller opening width optimizes these specific pixels for detecting large defocus conditions, while normal pixels maintain their standard characteristics for general image acquisition.
2Measurement precision
If focus detection pixels with larger opening width are used, then sensitivity to small defocus is improved, but detection accuracy for large defocus deteriorates
Solution Approach 1:
The opening width parameter of detection pixels is changed to be smaller than that of normal pixels. This parameter change optimizes the pixels for detecting large defocus conditions by reducing the amount of light that can bypass the focal point, thereby improving the contrast between in-focus and out-of-focus states.
3Adaptability or versatility
If detection pixels are positioned at different locations on the sensor, then coverage of different exit pupil distances is achieved, but light amount received by pixels becomes uneven
Solution Approach 1:
The patent achieves equipotentiality in terms of light reception by designing the optical system and pixel arrangement such that pixels at different positions on the sensor receive equal amounts of light. This is accomplished through careful design of the lens and pixel positioning to compensate for the varying exit pupil distances, ensuring uniform illumination across all detection pixels regardless of their location.
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 configuration significantly enhances focus detection accuracy, both for small and large defocus conditions, by ensuring that focus detection pixels receive equal light amounts regardless of their position on the sensor, thereby improving image quality and detection precision.
Implementation Method 1
a photodiode 12
Data Source
AI summary
An image sensor includes: a plurality of large-defocus detection pixel pairs configured to be used when a displacement of a focus is greater than a predetermined value; and a plurality of normal pixels arranged in a substantially matrix shape and configured to acquire an image. A large-defocus detection line including the large-defocus detection pixel pairs is provided for each of a predetermined number of lines, and on each of the large-defocus detection lines, the plurality of large-defocus detection pixel pairs are configured as a plurality of exit pupil distance-supporting large-defocus detection pixel pairs corresponding to different exit pupil distances.