Image Sensor Signal-Line Layout for Fast AF and Imaging Readout
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Solution Overview
Problem
Existing image sensors face challenges in speeding up signal reading for focus detection and image generation, particularly in efficiently handling signals from AF pixels and imaging pixels.
Innovation Solution
The image sensor design includes AF pixels and imaging pixels with photoelectric conversion units, light-shielding units, and a control unit that manages signal output through separate signal lines, allowing for parallel processing and sequential selection of pixel rows to enhance readout speed and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If signals from all pixels are read out through a single shared signal line, then device complexity is reduced, but signal reading speed decreases
Solution Approach 1:
The patent divides the pixel array into multiple regions (first region with first photoelectric conversion units and second region with second photoelectric conversion units), each region having dedicated signal lines for reading out signals simultaneously. This segmentation allows parallel signal reading, improving readout speed while maintaining manageable device complexity through organized regional structure.
2Productivity
If focus detection and image signal reading are performed simultaneously through the same signal lines, then processing efficiency is improved, but signal accuracy deteriorates
Solution Approach 1:
The patent separates focus detection pixels (first photoelectric conversion units with light-shielding units) and imaging pixels (second photoelectric conversion units) into different regions with dedicated signal lines. This allows simultaneous independent reading of focus detection signals and imaging signals without mutual interference, maintaining both processing efficiency and signal accuracy.
Solution Approach 2:
The patent extracts focus detection functionality into separate pixels with light-shielding units that block optical paths, allowing focus detection signals to be read out independently through dedicated signal lines. This extraction enables simultaneous focus detection and imaging without signal mixing, preserving accuracy while improving processing efficiency.
3Measurement precision
If light-shielding units are added to AF pixels, then focus detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies light-shielding units only to specific first photoelectric conversion units in the first region that are designated for focus detection, while the second photoelectric conversion units in the second region remain without such shielding. This local application of light-shielding structures improves focus detection accuracy through optical path control while limiting the increase in device complexity to only the necessary regions.
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 improves the accuracy of imaging pixel signals and accelerates the readout of AF pixel signals, reducing focus detection time and enhancing overall image sensor performance.
Implementation Method 1
a first photoelectric conversion unit that photoelectrically converts light to generate an electric charge
Data Source
AI summary
An image sensor, includes: a first pixel and a second pixel, in a first direction, each including a first photoelectric conversion unit and a light-shielding unit and outputting a signal; a third pixel and a fourth pixel, in the first direction, each including a second photoelectric conversion unit and outputting a signal; a first signal line and a second signal line, in the first direction, each of which can be connected to the first pixel, the second pixel, the third pixel and the fourth pixel; and a control unit that performs a first control in which a signal of the first pixel is output to the first signal line and a signal of the second pixel is output to the second signal line, and a second control in which a signal of the third pixel and a signal of the fourth pixel are output to the first signal line.