Independent Exposure Control for Phase-Difference AF Pixels
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Solution Overview
Problem
Current imaging apparatuses face challenges in achieving precise and high-speed autofocus due to hardware limitations, where automatic exposure settings for phase-difference AF pixels are the same as normal pixels, affecting AF precision and speed, especially during continuous AF servo.
Innovation Solution
A control device and method that independently control the exposure of a second pixel group, such as phase-difference detection pixels, based on a designated focus position, allowing for optimal AE settings distinct from the first pixel group, enhancing autofocus performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the AE settings of phase-difference AF pixels are the same as normal pixels due to hardware limitations, then the device complexity is reduced, but the autofocus precision and speed deteriorate
Solution Approach 1:
The imaging surface is divided into two distinct pixel groups: phase-difference AF pixels and normal pixels. Each group has independent exposure control settings, allowing the phase-difference AF pixels to use exposure parameters optimized for autofocus (such as higher luminance and different updating cycles) while normal pixels use settings optimized for image capture. This segmentation resolves the contradiction by enabling different exposure settings for different pixel types without increasing overall system complexity.
Solution Approach 2:
Different exposure control parameters are applied to different regions (pixel groups) based on their specific functions. The phase-difference AF pixels receive local exposure optimization (higher gain, different updating cycle) suited for autofocus detection, while normal pixels receive exposure settings optimized for image quality. This local quality approach allows each pixel group to operate at optimal performance without compromising the other.
2Ease of manufacture
If the AE settings of phase-difference AF pixels are the same as normal pixels, then the ease of manufacture is improved, but the autofocus speed deteriorates
Solution Approach 1:
The exposure control system is made dynamic by allowing different updating cycles for different pixel groups. Phase-difference AF pixels can be updated at a higher frequency optimized for tracking moving subjects during continuous AF servo, while normal pixels use a lower updating cycle appropriate for still image capture. This dynamic exposure control enables fast autofocus speed without requiring complex hardware manufacturing.
3Device complexity
If the exposure control of phase-difference AF pixels follows the AE-frame settings of normal pixels, then the device complexity is reduced, but the information accuracy for autofocus deteriorates
Solution Approach 1:
The exposure parameters (luminance, updating cycle) are changed specifically for phase-difference AF pixels to optimize autofocus performance. Phase-difference AF pixels use higher luminance settings and different updating cycles compared to normal pixels, ensuring accurate luminance information is captured for focus detection. This parameter change enables precise autofocus information without increasing device complexity.
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 enables improved autofocus precision and speed by optimizing AE settings for the phase-difference detection pixels, allowing for exposure control specific to autofocusing, thereby addressing the limitations of existing technologies.
Implementation Method 1
an imaging apparatus, such as a digital camera, equipped with an imaging element having a plurality of photo-electric converters
Data Source
AI summary
There is provided a control device that controls exposure of a first pixel group and a second pixel group disposed in a single imaging surface. The control device performs exposure control of the second pixel group independently of exposure control of the first pixel group in accordance with a designated focus position.