Solid-State Imaging Device Charge Release for Blooming Prevention
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Solution Overview
Problem
Conventional solid-state imaging devices with dummy pixels are limited in configurations where the photoelectric conversion portion is formed outside the Si substrate, as they cannot effectively reduce the influence of blooming on optical black pixels.
Innovation Solution
A solid-state imaging device with a charge releasing portion, such as a dummy pixel, disposed between aperture and optical black pixels, where the lower electrode is fixed at a constant voltage, connected to a power supply voltage wiring line, and surrounded by dummy pixels to release excess charges and prevent blooming effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dummy pixel is disposed between an aperture pixel and an OPB pixel to reduce blooming influence, then the OPB pixel can accurately detect dark current, but the device cannot be effectively applied in configurations where the photoelectric conversion portion is formed outside the Si substrate
Solution Approach 1:
The invention changes the electrical parameter configuration of the dummy pixel by connecting its lower electrode to a power supply voltage wiring line instead of leaving it floating or connecting it to a standard readout circuit. This parameter change enables the dummy pixel to function as a charge releasing portion that can accept and hold excess charges from aperture pixels through potential difference, making the blooming prevention mechanism applicable to configurations where the photoelectric conversion portion is formed outside the Si substrate.
2Object-affected harmful factors
If the lower electrode of the dummy pixel is connected to a power supply voltage wiring line, then excess charges can be released to prevent blooming, but the device complexity increases due to additional wiring connections
Solution Approach 1:
The power supply voltage wiring line serves multiple functions: it provides power to active pixels and simultaneously serves as a charge release path for dummy pixels. By making the wiring layer serve dual purposes, the invention prevents blooming without requiring separate dedicated wiring, thus minimizing the increase in device complexity.
Solution Approach 2:
The dummy pixel acts as an intermediary charge storage element between aperture pixels and OPB pixels. It mediates the charge flow by accepting excess charges from aperture pixels through potential difference and preventing them from reaching OPB pixels, thereby reducing blooming influence without requiring direct intervention in the signal readout path.
3Object-affected harmful factors
If dummy pixels surround the aperture pixel region, then charge release capability is enhanced, but the effective pixel area is reduced
Solution Approach 1:
Instead of completely surrounding the aperture pixel region with dummy pixels, the invention applies dummy pixels selectively at strategic locations where blooming is most likely to occur. This partial action approach provides sufficient charge release capability to prevent charge overflow while minimizing the loss of effective pixel area compared to complete surrounding.
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 effectively reduces the influence of blooming on optical black pixels, preventing charge flow from aperture to optical black pixels and maintaining high potential differences to prevent further charge transfer.
Implementation Method 1
a first photoelectric conversion portion (51), an upper electrode (52), and a lower electrode (53) formed outside a substrate (14), the first photoelectric conversion portion performing photoelectric conversion in accordance with incident light
Data Source
AI summary
A solid-state imaging device that is one aspect of the present disclosure has a first photoelectric conversion portion, an upper electrode, and a lower electrode formed outside a substrate, the first photoelectric conversion portion performing photoelectric conversion in accordance with incident light, the upper electrode and the lower electrode being formed to sandwich the first photoelectric conversion portion. The solid-state imaging device includes an aperture pixel that is disposed on a pixel array, and generates a normal pixel signal; an OPB pixel that is disposed at an end portion on the pixel array, and generates a pixel signal indicating a dark current component; and a charge releasing portion that is disposed between the aperture pixel and the OPB pixel, and releases electric charge flowing out from the aperture pixel.