Photoelectric Conversion Element Stabilizing Analog Processing
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Solution Overview
Problem
Conventional CMOS linear sensors in image reading devices experience image quality deterioration due to characteristic differences and noise fluctuations between pixels, leading to issues like coloring or false color, which are difficult to correct without increasing chip size or cost through dedicated correction circuits.
Innovation Solution
A photoelectric conversion element with an analog processing unit that performs preliminary operations using a signal supply unit to stabilize the operating conditions before processing analog signals from a pixel group, reducing load fluctuations and noise variations between pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a column system is used to increase driving speed by processing multiple pixels in parallel, then productivity is improved, but image quality deteriorates due to characteristic differences and noise fluctuations between pixels
Solution Approach 1:
The patent applies preliminary action by having the analog processing unit process a dummy signal before processing actual pixel signals. This preliminary processing stabilizes the operating state of the analog processing unit, ensuring that when real pixel signals are processed, the unit is already in a stable condition, thereby preventing characteristic differences and noise fluctuations that would otherwise degrade image quality.
2Manufacturing precision
If dedicated correction circuits are added to correct characteristic differences between pixels, then image quality is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies self-service by enabling the analog processing unit to correct its own characteristic differences through the dummy signal processing mechanism. The analog processing unit stabilizes its own operating state before processing pixel signals, eliminating the need for external dedicated correction circuits. This self-correction approach improves image quality while maintaining simple device architecture.
3Device complexity
If the analog processing unit processes signals sequentially without preliminary operation, then device complexity is reduced, but load fluctuation and switching noise cause gain errors and conversion errors between pixels
Solution Approach 1:
The patent applies preliminary action by inserting a dummy signal processing step before actual pixel signal processing. This preliminary action conditions the analog processing unit to be in a stable operating state, thereby preventing load fluctuation and switching noise from causing gain errors and conversion errors. The signal accuracy is improved without adding complex correction circuits.
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 approach effectively prevents image quality deterioration by ensuring uniform processing conditions across pixels, thereby improving color accuracy without the need for dedicated correction circuits, thus maintaining image quality and reducing costs.
Implementation Method 1
uses a photodiode (PD) to perform photoelectric conversion on incident light
Data Source
AI summary
A photoelectric conversion element comprises: a plurality of pixels, each of which performs photoelectric conversion and outputs an analog signal; and analog processing unit that sequentially processes, on a pixel-to-pixel basis, the analog signals output from a pixel group including the pixels; and a signal supply unit that supplies a signal needed fro preliminary operation to the analog processing unit so as to enable the analog processing unit to perform the preliminary operation before the analog processing unit starts to process the analog signals output from the pixel group.