Solid-State Imaging Column Circuit Adaptive Gain Switching
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Solution Overview
Problem
Existing solid-state imaging devices, such as those disclosed in Japanese Patent Application Laid-Open No. 2012-080252, fail to adequately reduce noise in low brightness conditions when reading out pixel signals with multiple types of gains, leading to insufficient noise reduction.
Innovation Solution
A solid-state imaging device with a pixel array unit and column circuits that operate in two modes: one mode amplifies signals at a common gain for both pixel signals, while the second mode amplifies signals at different gains to reduce noise, allowing for adaptive gain switching based on brightness conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a solid-state imaging device always reads out pixel signals with two types of gains regardless of brightness conditions, then the dynamic range is expanded, but noise reduction in low brightness conditions is insufficient
Solution Approach 1:
The column circuit is designed to dynamically switch between two operational modes based on the brightness level of the captured object. In the first mode, both pixel signals are amplified at a common gain for high brightness conditions. In the second mode, one pixel signal is amplified at a first gain while another is amplified at a second gain for low brightness conditions. This dynamic adaptation allows the system to optimize noise reduction while maintaining expanded dynamic range across varying brightness conditions.
2Object-affected harmful factors
If a column circuit amplifies signals at different gains, then noise reduction in low brightness conditions is improved, but the device complexity increases
Solution Approach 1:
The column circuit is designed with multi-functionality to handle both amplification modes within a single circuit architecture. The same column circuit can operate in the first mode (common gain amplification) for high brightness conditions and switch to the second mode (different gain amplification) for low brightness conditions. This universal design avoids the need for separate dedicated circuits for each mode, thereby reducing overall device complexity while still achieving effective noise reduction.
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 effectively reduces noise in low brightness conditions by using multiple gain settings, enhancing the signal-to-noise ratio and dynamic range of the imaging system.
Implementation Method 1
a pixel array unit in which a plurality of pixels each including a photoelectric converter are arranged
Data Source
AI summary
A solid-state imaging device includes a pixel array unit in which pixels each including a photoelectric converter are arranged over rows and columns, output lines each connected to the pixels arranged on a corresponding column, and column circuits each connected to a corresponding output line. Each column circuit is configured to operate in a first mode and a second mode, in the first mode, the common circuit amplifies a single signal based on charges generated in the photoelectric converter of one pixel connected to the corresponding output line at a common gain to output a first pixel signal and a second pixel signal, and in the second mode, the column circuit amplifies the single signal at a first gain to output a first pixel signal and amplifies the single signal at a second gain lower than the first gain to output a second pixel signal.