Solid-State Image Sensor Dual Readout Lines
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Solution Overview
Problem
As the number of pixels in solid-state image sensors increases, the rate of signal readout required for high-speed continuous shooting becomes a challenge due to the need for efficient signal transfer without significant parasitic capacitance and crosstalk, which affects the signal-to-noise ratio and color mixing.
Innovation Solution
A solid-state image sensor design with a pixel array where each pixel column includes two column readout lines, dividing pixel rows into groups to minimize the distance between photoelectric conversion elements and readout lines, reducing parasitic capacitance and crosstalk, and improving charge-voltage conversion gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of pixels is increased to improve resolution, then the image quality is improved, but the signal readout rate becomes insufficient and parasitic capacitance increases
Solution Approach 1:
The pixel array is divided into multiple banks, with each bank having independent readout circuits. This segmentation allows parallel readout of signals from different regions, effectively increasing the overall signal readout rate while maintaining high pixel density for improved resolution.
Solution Approach 2:
Multiple column readout lines are provided in each pixel column, extending the readout capability from a single line to multiple lines simultaneously. This dimensional expansion of the readout path enables higher readout rates without increasing the physical pixel density, thus maintaining image resolution while improving productivity.
2Productivity
If multiple column readout lines are provided in each pixel column to increase readout rate, then the signal readout rate is improved, but parasitic capacitance and crosstalk increase
Solution Approach 1:
The patent applies different design approaches to different regions: in regions where column readout lines are closely spaced, shielding structures are introduced to reduce crosstalk. In other regions, the layout is optimized to maximize spacing. This localized quality adjustment allows multiple readout lines to operate with minimal parasitic capacitance and crosstalk interference.
Solution Approach 2:
Shielding structures are introduced as intermediary elements between adjacent column readout lines. These shields act as mediators that block electromagnetic interference and reduce capacitive coupling, thereby reducing crosstalk and parasitic capacitance effects while allowing multiple readout lines to function at high speed.
3Object-generated harmful factors
If column readout lines are positioned far from conversion regions to reduce crosstalk, then color mixing is reduced, but the distance for charge transfer increases and signal loss increases
Solution Approach 1:
Shielding structures are positioned between the conversion regions and column readout lines, acting as intermediaries that allow the readout lines to be placed closer to conversion regions without increasing crosstalk. This enables short charge transfer paths for signal integrity while maintaining color separation through the shielding effect.
Solution Approach 2:
The shielding structures are connected to a reference potential, creating equipotential regions that prevent voltage fluctuations in the readout lines from coupling into the conversion regions. This allows closer positioning of readout lines to conversion regions without increasing color mixing, as the shielding maintains electrical isolation.
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 design enhances the signal-to-noise ratio and reduces color mixing by minimizing capacitive coupling between conversion regions and readout lines, enabling efficient high-speed signal readout and improved image quality.
Implementation Method 1
each pixel includes a photoelectric conversion element
Data Source
AI summary
In an image sensor including a first column readout line and a second column readout line provided to each pixel column, a plurality of pixel rows are divided into pixel rows of a first group and pixel rows of a second group, pixels of the pixel rows of the first group output signals to the first column readout line, and pixels of the pixel rows of the second group output signals to the second column readout line. A shortest distance between a conversion region of a first pixel of a pixel row of the first group and the first column readout line to which a signal from the first pixel is output is not more than a shortest distance between the conversion region of the first pixel and the second column readout line to which the signals from the pixels belonging to the pixel rows of the second group are output.