Photoelectric Conversion Element Clock Segmentation for Noise Reduction
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Solution Overview
Problem
Conventional image reading devices using spread spectrum clocks for CCD or CMOS sensors experience periodic noise and insufficient noise reduction due to unnecessary radiation, especially at increased processing speeds.
Innovation Solution
A photoelectric conversion element with parallel-serial conversion units that convert analog signals from multiple light receiving elements into digital signals, using a combination of spread spectrum and non-spread spectrum clocks to reduce noise and radiation interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If spread spectrum clock is used to drive CCD or CMOS sensor, then unnecessary radiation (EMI) is reduced, but periodic noise and stripes occur in the image
Solution Approach 1:
The patent segments the clock signal generation into two independent paths: an analog clock generation circuit using a reference clock oscillator for the photoelectric conversion element, and a digital clock generation circuit using a spread spectrum clock for digital processing. This segmentation allows each circuit to use the appropriate clock type, preventing periodic noise while maintaining EMI reduction benefits.
2Productivity
If processing speed is increased, then productivity is improved, but noise reduction due to unnecessary radiation becomes insufficient
Solution Approach 1:
The patent divides the system into analog and digital domains with separate clock sources. The analog photoelectric conversion uses a stable reference clock to maintain signal integrity at high speeds, while the digital processing uses spread spectrum clock for EMI reduction, enabling high productivity without compromising noise reduction.
Solution Approach 2:
The patent changes the clock frequency parameters dynamically - using a reference clock frequency for analog conversion to maintain stability at high processing speeds, and spread spectrum frequency modulation for digital circuits to reduce radiation. This parameter optimization allows high productivity while maintaining effective noise reduction.
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
The solution significantly reduces noise and radiation interference, allowing for more efficient image processing with reduced occurrence of periodic noise and stripes in the image, even at higher processing speeds.
Implementation Method 1
a plurality of light receiving elements 300 that store charge obtained through photoelectric conversion
Data Source
AI summary
A photoelectric conversion element includes: a plurality of AD conversion units that convert respective analog signals representing amounts of charge stored in a plurality of light receiving elements into digital signals in parallel; and a parallel-serial conversion unit that performs parallel-serial conversion on the digital signals into which the analog signals have been converted in parallel by the AD conversion units.