Solid State Imaging Pixel Driving for Charge Lag Reduction
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Solution Overview
Problem
In solid state imaging devices, charges remaining in the connecting portion between the photoelectric converting element and the semiconductor substrate cause lag and non-linearity in signal output, making it difficult to achieve high sensitivity and linearity correction.
Innovation Solution
The implementation of a driving unit that sets the connecting portion and potential barrier portion to the same potential by varying the potential of the potential barrier portion, ensuring that charges generated during exposure do not remain in the connecting portion, and incorporating a reset transistor to discharge unnecessary charges, thereby preventing lag and enabling linearity correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If charges are accumulated in the connecting portion during exposure, then the photoelectric conversion efficiency is improved, but charge lag and non-linearity occur in signal output
Solution Approach 1:
The patent applies equipotentiality by setting the potential of the connecting portion equal to the potential of the semiconductor substrate through controlled charge discharge. This eliminates potential differences that cause charge accumulation and lag, ensuring linear signal output while maintaining efficient photoelectric conversion.
Solution Approach 2:
The patent changes the electrical potential parameter of the connecting portion by controlling charge discharge to ground. By dynamically adjusting the potential state from charged to discharged, the system prevents charge lag and maintains signal linearity without compromising photoelectric conversion efficiency.
2Reliability
If the potential of the potential barrier portion is varied to match the connecting portion potential, then charge lag is prevented, but device complexity increases
Solution Approach 1:
The patent implements self-service by using the photoelectric converting element itself to discharge charges from the connecting portion to ground. The element autonomously manages its own charge state without requiring external control circuitry, preventing charge lag while maintaining simple device architecture.
Solution Approach 2:
The patent merges the charge discharge function with the photoelectric converting element structure. The connecting portion, potential barrier portion, and discharge path are integrated into a unified structure that automatically equalizes potentials during normal operation, eliminating the need for separate potential control mechanisms.
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 prevents charge lag and allows for linearity correction in the signal output characteristic, improving the sensitivity and linearity of the imaging device by ensuring that the connecting and potential barrier portions are at the same potential, thereby stabilizing the signal output.
Implementation Method 1
a photoelectric converting layer arranged between the pair of electrodes; wherein each of the plurality of pixels includes: a connecting portion that is arranged in the semiconductor substrate and that is connected electrically to one of the pair of electrodes
Data Source
AI summary
An imaging device includes a solid state imaging element that includes a plurality of pixels; and a driving unit; wherein each pixel includes: a photoelectric converting element includes a pair of electrodes stacked above a semiconductor substrate and a photoelectric converting layer arranged between the electrodes; a connecting portion that is arranged in the semiconductor substrate; a potential barrier portion; a first charge accumulating portion; and a signal output circuit, and wherein the driving unit executes such a same potential driving that the connecting portion and the potential barrier portion are set to have a same potential by varying the potential of the potential barrier portion.