Image Sensor Pixel Readout for Fast Focus Detection and Low Noise
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Solution Overview
Problem
Conventional image sensors are unable to effectively obtain and read out signals from a given number of pixels, leading to inefficiencies in image capture and focus detection.
Innovation Solution
The image sensor comprises a first photoelectric conversion unit, multiple second photoelectric conversion units, output units, and control lines that allow for selective output and reading of signals from pixels, enabling the summation of signals from a group of pixels and reducing noise through source-follower-addition, while maintaining signal accuracy by controlling the output of different pixel types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional image sensor reads out signals from all pixels simultaneously, then complete image data is obtained, but noise increases and focus detection efficiency decreases
Solution Approach 1:
The patent segments pixels into different types (first pixels for focus detection, second pixels for image generation) with separate photoelectric conversion units and output units. This segmentation allows selective reading of signals from different pixel types, enabling noise reduction by processing focus detection signals separately from image signals, thereby improving signal accuracy without reading all pixels simultaneously.
Solution Approach 2:
The patent implements dynamic control over pixel output through separate control lines for first and second pixels. The reading control unit can dynamically select which pixel signals to read out based on operational mode (focus detection vs. image capture), enabling flexible noise management and efficient focus detection without compromising image quality.
2Productivity
If signals from all pixels are read out for image generation, then complete image data is obtained, but focus detection speed decreases
Solution Approach 1:
The patent segments the pixel array into first pixels dedicated to focus detection and second pixels dedicated to image generation, with separate photoelectric conversion units and output units. This segmentation enables independent processing channels where focus detection signals can be read out quickly without waiting for complete image data acquisition, thereby improving focus detection speed while maintaining image capture efficiency.
Solution Approach 2:
The patent implements dynamic control over pixel output through separate control lines for first and second pixels. The reading control unit can dynamically select which pixel signals to read out based on operational mode (focus detection vs. image capture), enabling flexible speed optimization for focus detection without compromising image capture efficiency.
3Ease of operation
If separate output lines are provided for each pixel type, then signal processing is simplified, but device complexity increases
Solution Approach 1:
The patent merges the output paths of first and second pixels into a single common output line. The first output unit and second output units both connect to the same output line, which is controlled by the reading control unit to selectively read signals from different pixel types. This merging approach simplifies the output line configuration and reduces device complexity while maintaining ease of operation through controlled selective reading.
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 configuration allows for efficient image data generation with reduced noise, enabling high-speed focus detection and improved image quality by selectively outputting and processing signals from various pixel types.
Implementation Method 1
a first photoelectric conversion unit that photoelectrically converts light to generate an electric charge
Implementation Method 2
a plurality of second photoelectric conversion units that photoelectrically convert light to generate electric charges
Data Source
AI summary
An image sensor includes: a first photoelectric conversion unit that photoelectrically converts light to generate an electric charge; a first output unit that outputs a first signal based on the electric charge generated by the first photoelectric conversion unit; a plurality of second photoelectric conversion units that photoelectrically convert light to generate electric charges; a plurality of second output units that output second signals based on the electric charges generated by the second photoelectric conversion units; an output line to which the first output unit and the plurality of second output units are connected, and from which at least one of the first signal and the second signals is output; a first control line for controlling the output of the first signal from the first output unit; and second control lines for controlling the outputs of the second signals from the plurality of second output units.