Image Sensor with Independent Pixel Charge Storage Control
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Solution Overview
Problem
Existing image-capturing devices face delays in operational sequences for focus detection and viewfinder display, with prolonged processing times and slow refresh rates due to simultaneous storage requirements at focus detection pixels.
Innovation Solution
An image sensor with independently controlled charge storage times for image-capturing and focus detection pixels, allowing separate and optimized storage and output cycles for each type of pixel, enabling concurrent focus detection and viewfinder display without compromising refresh rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If focus detection pixels store charges for a long period to improve focus detection accuracy, then measurement precision is improved, but the refresh rate at the viewfinder becomes slow
Solution Approach 1:
The image sensor is divided into two distinct pixel types: image-capturing pixels for viewfinder display and focus detection pixels for autofocus control. Each pixel type has independent charge storage control, allowing focus detection pixels to maintain long integration times for high precision while image-capturing pixels provide continuous refresh for the viewfinder display.
Solution Approach 2:
The patent implements dynamic control of charge storage times through separate storage control signals for different pixel types. The control unit can independently adjust the integration time of focus detection pixels based on lighting conditions and focus detection requirements, while maintaining appropriate refresh rates for image-capturing pixels.
2Device complexity
If the image sensor sequentially executes image-capturing operations for focus detection and viewfinder display, then device complexity is reduced, but productivity decreases due to significant time delay
Solution Approach 1:
The patent merges focus detection and image capture functions into a single image sensor array, with both operations occurring simultaneously during the same exposure period. This eliminates sequential execution delays while maintaining relatively simple device architecture through shared photoelectric conversion elements.
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 solution allows for efficient focus detection while maintaining a constant refresh rate at the viewfinder, even in low light conditions, by extending charge storage time for focus detection pixels and adjusting storage times based on brightness levels.
Implementation Method 1
image-capturing photoelectric conversion portion at which an electrical charge corresponding to light entering therein during the first charge storage time is stored
Data Source
AI summary
An image sensor includes: image-capturing pixels that generate first image signals with a charge storage time controlled by a first storage control signal; and focus detection pixels that generate second image signals with a charge storage time controlled by a second storage control signal generated independently of the first storage control signal.