Solid-State Imaging Device Row Scanning Unit for Coupling Noise Reduction
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Solution Overview
Problem
Conventional solid-state imaging devices experience image quality degradation due to coupling noise and non-linear traveling characteristics of mechanical curtain shutters, particularly in multiple-pixel one-cell structures where photodiodes share reset transistors and floating diffusion units.
Innovation Solution
The implementation of a solid-state imaging device with a row scanning unit that performs simultaneous pixel reset scans on different rows, matching the traveling characteristics of mechanical curtain shutters, and using register groups to adjust the number of rows and pulse width for each reset operation, thereby preventing coupling noise and ensuring proper reset of photodiodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If pixel reset scan is performed sequentially row by row, then coupling noise between neighboring rows is reduced, but reset time is extended and image quality degradation occurs
Solution Approach 1:
The patent segments the pixel reset operation into two independent phases: a first pixel reset scan that resets all pixels simultaneously, and a second pixel reset scan that resets only the current row after transfer. This segmentation allows simultaneous reset of all pixels to minimize coupling noise while maintaining proper reset timing through the second scan phase.
Solution Approach 2:
The patent performs a preliminary first pixel reset scan that resets all pixels in the imaging area before the main readout operation. This preliminary action ensures all pixels are reset to a known state before the second pixel reset scan differentiates between rows, preventing coupling noise while ensuring proper reset timing.
2Device complexity
If multiple photodiodes share reset transistor and floating diffusion unit, then device complexity is reduced, but reset state gap occurs between neighboring rows causing image quality degradation
Solution Approach 1:
The patent segments the reset operation into two scans: first, all pixels are reset simultaneously; second, only the current row pixels are reset after transfer. This segmentation ensures that even in shared unit cell structures, each pixel receives proper reset timing, eliminating reset state gaps between rows while maintaining the simplified shared structure.
Solution Approach 2:
The first pixel reset scan performs a preliminary reset of all pixels before the second scan differentiates rows. This preliminary action ensures uniform reset state across all pixels initially, and the second scan maintains this uniformity by resetting only the current row after transfer, preventing reset state gaps.
3Device complexity
If electronic front curtain shutter is implemented using pixel reset scan, then mechanical shutter complexity is reduced, but non-linear traveling characteristics of mechanical shutter cause noise variation across rows
Solution Approach 1:
The patent implements dynamic row selection in the second pixel reset scan based on the current row being processed. By making the reset operation adaptive to the current row position and using the relationship between transfer timing and mechanical shutter characteristics, the system compensates for non-linear traveling characteristics and maintains exposure timing accuracy.
Solution Approach 2:
The patent uses feedback from the transfer timing and mechanical shutter characteristics to dynamically adjust the second pixel reset scan operation. The row scanning unit determines which pixels to reset based on feedback from the current row position and mechanical shutter state, compensating for non-linearities and maintaining precision.
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 reduces image quality degradation by preventing coupling noise and ensuring thorough reset of photodiodes, even with non-linear shutter characteristics, thereby enhancing image capture quality.
Implementation Method 1
two or more photodiodes PD each of which converts incident light into electric charges
Data Source
AI summary
A row scanning unit activates a synchronous curtain shutter mode in which pixel reset scan is performed and exposure of the imaging area is started by the pixel reset scan and is ended by light shielding by a mechanical curtain shutter, the pixel reset scan meaning that scan on a row-by-row basis is performed on pixel reset in which the photodiodes are reset by turning on the transfer transistors and a corresponding reset transistor, wherein in the mechanical curtain synchronous shutter mode, the pixel reset scan according to the traveling characteristics of the mechanical curtain shutter is performed, and the pixel reset scan includes performing a pixel reset operation simultaneously on the unit cells of different rows.