Image Pickup Pixel Readout Control for Focus and Image Signal Trade-offs
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Solution Overview
Problem
Existing image pickup devices face challenges in efficiently generating both image and focus detection signals using pixels divided for focus detection, as they often require trade-offs between noise levels and dynamic ranges in different modes, leading to suboptimal performance in prioritizing image or focus detection.
Innovation Solution
The image pickup apparatus and method control the image pickup section to perform specific readout operations in different frames, generating and reading out pixel signals for focus detection in one direction and image signals by adding or subtracting photoelectric conversion signals from multiple pixels, optimizing signal quality and reducing noise and dynamic range issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If one pixel for image is divided into multiple pixels for focus detection to enable phase difference detection, then focus detection capability is improved, but the dynamic range and signal-to-noise ratio for image capture deteriorate
Solution Approach 1:
The patent implements dynamic switching between two readout modes: a first readout mode that reads out signals from all photoelectric conversion sections for focus detection, and a second readout mode that adds up signals from multiple photoelectric conversion sections to improve image signal quality. The system dynamically selects the appropriate readout mode based on whether focus detection or image capture is prioritized, resolving the contradiction between focus detection capability and image signal quality
Solution Approach 2:
The patent changes the signal processing parameters by switching between different readout modes. In the first readout mode, individual pixel signals are read out for focus detection. In the second readout mode, the signal processing parameter changes to add up signals from multiple photoelectric conversion sections, thereby improving the signal-to-noise ratio and dynamic range for image capture while maintaining focus detection capability
2Measurement precision
If pixel signals are read out for both image and focus detection in every frame, then focus detection accuracy is improved, but data processing complexity and power consumption increase
Solution Approach 1:
The patent implements periodic switching between different readout modes rather than continuously performing both readouts. The system alternates between the first readout mode (optimized for focus detection) and the second readout mode (optimized for image quality), reducing the frequency of full dual-mode operations and thereby lowering data processing complexity and power consumption while maintaining adequate focus detection accuracy through the periodic acquisition of focus detection data
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 allows for high signal-to-noise ratio and wide dynamic range pixel signals for both focus detection and image capture, enabling improved accuracy and quality in various camera modes by prioritizing either focus detection or image signals based on operational needs.
Implementation Method 1
a pixel for image being divided into a plurality of pixels for focus detection that respectively photoelectrically convert light beams passing regions formed by dividing an exit pupil of a photographing optical system into a plurality of pupils and generate photoelectric conversion signals
Data Source
AI summary
An image pickup apparatus includes a pixel section in which a pixel for image is divided into a plurality of pixels for focus detection that generate photoelectric conversion signals, the pixel section generating a pixel signal for image and pixel signals for focus detection on the basis of the photoelectric conversion signals, and a device control section or the like configured to control the pixel section to perform, in a frame, first readout for generating both of a pair of the pixel signals for focus detection and reading out the pair of pixel signals for focus detection and perform, in another frame, second readout for generating one of the pair of pixel signals for focus detection, adding up the photoelectric conversion signals to generate the pixel signal for image, and reading out one of the generated pixel signals for focus detection and the pixel signal for image.