Solid-State Image Sensor Global Shutter PLS Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In existing image sensors, parasitic light sensitivity (PLS) varies across rows due to line-sequential signal reading, leading to image quality degradation, and converting to a back-surface irradiation type with a shielded structure is challenging.
Innovation Solution
A solid-state image pickup device with a pixel array unit incorporating a photoelectric conversion element, an overflow integration capacitor, and an AD converter, allowing for simultaneous exposure and AD conversion across all pixels, thereby minimizing PLS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If line-sequential signal reading is performed in a front-surface irradiation type image sensor, then the structure is simple and manufacturing is easier, but parasitic light sensitivity (PLS) varies across rows causing image quality degradation
Solution Approach 1:
The patent divides the pixel array into multiple independently controllable banks, where each bank can perform exposure and readout operations simultaneously. This segmentation allows different rows to be at different stages of the imaging process at the same time, eliminating the cumulative PLS effect that occurs in sequential reading architectures.
Solution Approach 2:
The patent implements a global shutter mechanism that performs preliminary exposure capture for all pixels simultaneously before readout begins. This allows the photoelectric conversion elements to complete their exposure and transfer charges to storage regions before any readout operations start, preventing PLS from affecting the captured image data.
2Object-affected harmful factors
If the image sensor is changed to a back-surface irradiation type with a shielded structure, then PLS is reduced, but the structure becomes complex and difficult to realize
Solution Approach 1:
The patent extracts and removes the light shield structure from the back-surface irradiation design. Instead of using physical shields to block parasitic light, the invention achieves PLS suppression through the global shutter mechanism that completes exposure before readout, making the complex shielded structure unnecessary.
Solution Approach 2:
The patent replaces the mechanical/physical light shield structure with a temporal control mechanism. Instead of using physical barriers to prevent parasitic light, the invention uses timing control to ensure exposure is completed and charges are transferred to storage regions before readout operations that could introduce PLS, thereby eliminating the need for complex shielded structures.
3Manufacturing precision
If exposure time is controlled to be the same in all pixels, then exposure uniformity is improved, but reading must be performed line-sequentially increasing PLS in final read-out rows
Solution Approach 1:
The patent performs the exposure action preliminarily for all pixels simultaneously using the global shutter mechanism. All photoelectric conversion elements capture light for the exact same duration before any readout operations begin. This preliminary exposure ensures uniformity across all rows while the subsequent simultaneous readout prevents PLS from affecting the already-captured image data.
Solution Approach 2:
The patent maintains continuous useful action by enabling simultaneous exposure and readout operations across multiple pixel banks. While one bank is being read out, other banks can simultaneously perform exposure, ensuring that the useful imaging action continues without interruption and that no row suffers from PLS due to delayed readout.
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 ensures uniform PLS across all pixels, enhancing image quality by maintaining a broad dynamic range and reducing image degradation due to parasitic light sensitivity.
Implementation Method 1
a first unit pixel at least having one photoelectric conversion element
Data Source
AI summary
While realizing a broad dynamic range, the present technology relates to a solid-state image pickup device and control method therefor, and electronic apparatus aiming at enabling an influence of PLS to be suppressed.The solid-state image pickup device includes a pixel array unit in which a plurality of pixels are arrayed. A portion of pixels in the pixel array unit are a unit pixel at least having one photoelectric conversion element and over flow integration capacitor. Further, the solid-state image pickup device includes one AD converter for one or more unit pixels in the pixel array unit. The present technology is applicable to, for example, the solid-state image pickup.