Image Sensor Pixel Segmentation for Noise Reduction and Fast Focus
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Solution Overview
Problem
Existing image capturing systems that acquire both focus detection and image signals from the same pixel generate higher noise levels, leading to deteriorated image quality, especially under high sensitivity conditions, and struggle to follow fast-moving subjects due to prolonged focus control times.
Innovation Solution
An image capturing apparatus and method that alternates between two acquisition modes: one for recording images using all pixels and another for focus detection images using a subset of pixels, allowing for continuous image capturing while minimizing noise and improving focus accuracy by controlling the number of pixels used for each signal based on image capturing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If both focus detection signal and image signal are acquired from the same pixel, then focus detection capability is improved, but noise level increases and image quality deteriorates
Solution Approach 1:
The image sensor is divided into two distinct regions: a first region with pixels that acquire only image signals, and a second region with pixels that acquire both image signals and focus detection signals. This segmentation allows the system to obtain focus detection capability while isolating the noise-generating pixels to a specific region, thereby preventing noise from affecting the entire image and maintaining overall image quality.
2Measurement precision
If focus control is performed based on focus detection signal from first image capturing, then focus adjustment is achieved, but time required for second image capturing increases and fast moving subjects cannot be tracked
Solution Approach 1:
The system performs focus detection and focus adjustment in advance during the first image capturing process. By acquiring focus detection signals and completing focus adjustment before the second image capturing, the system eliminates time loss during the shooting process, enabling fast tracking of moving subjects without compromising focus accuracy.
3Adaptability or versatility
If pixels are divided into regions for focus detection and image signal acquisition, then focus detection function is added, but device complexity increases
Solution Approach 1:
Pixels in the second region are designed to perform dual functions: acquiring both image signals and focus detection signals simultaneously. This multi-functionality allows the system to add focus detection capability without requiring completely separate dedicated focus detection pixels, thereby reducing the increase in device complexity while maintaining versatility.
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 approach reduces noise variations and enhances image quality by optimizing pixel usage, enabling faster and more accurate focus tracking, especially under high sensitivity conditions and when capturing fast-moving subjects.
Implementation Method 1
each pixel including a plurality of photoelectric conversion units that generate focus detection signals from light flux that have passed through different regions in an exit pupil
Data Source
AI summary
There is provided an image capturing apparatus. An image capturing unit acquires a signal in a first acquisition mode or a second acquisition mode for each pixel of an image sensor. In the first acquisition mode, an image signal obtained by adding focus detection signals of a plurality of photoelectric conversion units of the pixel is acquired. In the second acquisition mode, the focus detection signals are acquired in addition to the image signal. The image capturing alternately captures a recording image and a focus detection image having a smaller number of pixels than the recording image, applies all pixels to the first acquisition mode when capturing the recording image, and applies at least a part of the pixels to the second acquisition mode when capturing the focus detection image.