Independent Exposure Control for Phase-Difference and Monitor Pixels
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Solution Overview
Problem
Existing imaging apparatuses face challenges in achieving optimal autofocus (AF) and automatic exposure (AE) performance due to the limitations in independently controlling phase-difference pixels and monitor pixels, leading to issues with shutter speed, ISO settings, and aperture value selection, which affect the quality of the monitor image and autofocus speed.
Innovation Solution
A control device and method that allow independent exposure control of phase-difference pixels and monitor pixels by adjusting gain and exposure time, enabling optimal AE and AF performance by setting distinct control values for each pixel group within a single imaging surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same control values are applied to both monitor pixels and phase-difference pixels, then the control system is simple, but AF performance and brightness are insufficient
Solution Approach 1:
The imaging sensor is divided into two distinct pixel groups: monitor pixels and phase-difference pixels. Each group is assigned independent control values for gain and exposure time, allowing optimized control for their respective functions. This segmentation resolves the contradiction by enabling function-specific optimization without requiring a completely separate control system.
Solution Approach 2:
Different control values are applied to different regions of the imaging sensor. Monitor pixels receive control values optimized for image quality and smoothness, while phase-difference pixels receive control values optimized for brightness and AF detection accuracy. This local differentiation allows each pixel type to operate at its optimal performance point.
2Device complexity
If shutter speed and ISO values are set to fixed values, then the control system is simple, but the interlocking range is narrow and AF performance deteriorates
Solution Approach 1:
The system transitions from fixed control values to dynamic, adjustable control values. The control unit can independently adjust gain and exposure time for each pixel group based on detected brightness levels and AF requirements. This dynamic adjustment expands the interlocking range and allows adaptation to various lighting conditions and AF scenarios.
Solution Approach 2:
The system changes the parameters of control values (gain and exposure time) independently for each pixel group. By allowing variable adjustment of these parameters rather than using fixed values, the system achieves a wider interlocking range and better adaptability to different imaging conditions while maintaining manageable system complexity.
3Manufacturing precision
If monitor pixels are smoothed to avoid hunting, then image quality is improved, but AF speed decreases when using identical exposure values
Solution Approach 1:
The system segments the pixel control into two independent pathways: one for monitor pixels optimized for smoothness and image quality, and another for phase-difference pixels optimized for speed and brightness. This segmentation allows monitor pixels to be smoothed for quality while phase-difference pixels maintain faster response for AF detection.
Solution Approach 2:
Different processing characteristics are applied locally to different pixel groups. Monitor pixels receive smoothing processing to eliminate hunting and ensure image quality, while phase-difference pixels receive faster, less smoothed processing to maintain AF speed. This local quality differentiation resolves the contradiction between image quality and AF speed.
4Illumination intensity
If exposure correction is applied to monitor pixels, then image brightness is adjusted, but AF performance deteriorates when the same correction is applied to phase-difference pixels
Solution Approach 1:
The system segments exposure control into independent channels for monitor pixels and phase-difference pixels. Exposure correction can be applied to monitor pixels to adjust image brightness for the user, while phase-difference pixels maintain their own exposure settings optimized for AF detection accuracy. This segmentation prevents AF performance deterioration.
Solution Approach 2:
Different exposure control characteristics are applied locally to each pixel group. Monitor pixels receive exposure correction for brightness optimization, while phase-difference pixels maintain fixed or differently adjusted exposure values to preserve AF performance. This local differentiation allows simultaneous optimization of both functions.
Data Source
AI summary
There is provided a control device including a control unit configured to perform exposure control of a first pixel group and exposure control of a second pixel group independently of each other, the first pixel group and the second pixel group being disposed in a single imaging surface. The control unit controls gain or an exposure time of the first pixel group and gain or an exposure time of the second pixel group independently of each other.