Imaging Device Switch Circuit for Noise Reduction
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Solution Overview
Problem
In low power consumption mode, imaging devices using only one column ADC exhibit visible noise as vertical lines, leading to deterioration in image quality due to variations specific to the column ADC.
Innovation Solution
A solid-state imaging device with comparators in each column that can switch between parallel and sequential connection configurations for AD conversion, allowing alternation between active and standby states of comparators to reduce noise visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If only one column ADC is used in low power consumption mode, then power consumption is reduced, but image quality deteriorates due to visible vertical line noise
Solution Approach 1:
The patent applies dynamics by making the connection configuration between pixels and comparators switchable between parallel and sequential modes. The switching unit dynamically reconfigures the circuit topology based on operating mode, allowing the system to adapt between high-speed parallel processing and low-power sequential processing while managing noise visibility through controlled comparator usage.
Solution Approach 2:
The patent implements periodic action by alternately switching between different comparators in sequential mode. Instead of continuously using a single comparator which creates visible vertical line noise, the system periodically switches between multiple comparators (e.g., comparator 32-1 and comparator 32-2) to distribute the noise temporally, making it less visible and reducing overall noise impact in low power consumption mode.
2Speed
If multiple comparators are used in parallel for high-speed imaging, then imaging speed is improved, but power consumption increases
Solution Approach 1:
The switching unit dynamically reconfigures the connection between pixels and comparators based on the required operating mode. In high-speed imaging mode, multiple comparators are connected in parallel to simultaneously process multiple pixel signals, maximizing imaging speed. In low power consumption mode, the same comparators are reconfigured to process signals sequentially, reducing power consumption while maintaining acceptable performance.
Solution Approach 2:
The same set of comparators serves multiple functions across different operating modes. The comparators can operate in parallel for high-speed imaging or sequentially for low-power mode, making the comparator array universal and multi-functional. This eliminates the need for separate hardware configurations for different speed/power requirements.
3Reliability
If comparators are always active for high image quality, then image quality is maintained, but power consumption increases
Solution Approach 1:
The system uses periodic switching between multiple comparators in low power consumption mode. Instead of keeping a single comparator continuously active (which would consume power and create visible noise), the system periodically activates different comparators in sequence. This temporal distribution of comparator activity reduces the average power consumption while the periodic switching pattern helps mask the noise, maintaining acceptable image quality.
Solution Approach 2:
The connection configuration between pixels and comparators is dynamically adjusted based on power consumption requirements. In low power consumption mode, the switching unit reconfigures the circuit to use comparators sequentially rather than in parallel, reducing the number of simultaneously active comparators and thus reducing power consumption while maintaining image quality through intelligent signal routing.
Data Source
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Figure 3A~3B
AI summary
An imaging device includes a plurality of pixels arranged in rows and columns. The plurality of pixels include a first pixel and a second pixel. A first signal line is coupled to the first pixel. A second signal line is coupled to the second pixel. The imaging device includes first comparator and a second comparator displaced from the first comparator in a column direction. The imaging device includes a switch circuit configured to couple the first signal line to the first comparator and the second comparator, and couple the second signal line to the first comparator and the second comparator.