Range Sensor Charge Transfer Optimization
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Solution Overview
Problem
Conventional range sensors with a rectangular light receiving region face challenges in achieving high-speed charge transfer and enhanced sensitivity due to limitations in charge collection and transfer rates, particularly near the short sides, which degrades the sensor's performance.
Innovation Solution
The range sensor incorporates a planar shape with a pair of long and short sides, featuring signal charge collecting regions arranged opposite each other with a light receiving region in between, and unnecessary charge collecting gate electrodes with specific electrode portions to manage charge transfer and prevent unnecessary charge accumulation, allowing for quick signal charge transfer while maintaining sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the light receiving region is made rectangular with signal charge collecting regions arranged opposite each other, then the sensitivity is enhanced and charge transfer rate increases, but charge generated near the short sides cannot be quickly transferred
Solution Approach 1:
The patent divides the charge collection function into multiple segments: signal charge collecting regions at opposite corners and unnecessary charge collecting regions at the other two corners. This segmentation allows different charge paths to be optimized independently, solving the problem of incomplete charge transfer near short sides while maintaining high transfer rates.
Solution Approach 2:
The patent applies different electrode configurations to different regions: transfer electrodes are positioned to create strong electric fields near long sides for high-speed transfer, while unnecessary charge collecting gate electrodes are positioned near short sides to ensure complete charge collection. This local optimization resolves the contradiction between transfer speed and completeness.
2Measurement precision
If the area of signal charge collecting regions is increased to enhance sensitivity, then more charge can be collected, but the capacitance increases and voltage change decreases
Solution Approach 1:
The patent segments the charge collecting function between signal charge collecting regions (for sensitivity) and unnecessary charge collecting regions (for charge management). By separating these functions into different regions, the signal charge collecting regions can be optimized for sensitivity without being constrained by the need to handle all charge types, thus maintaining low capacitance while achieving high sensitivity.
Solution Approach 2:
The patent extracts the unnecessary charge collection function from the signal charge collecting regions and places it in separate unnecessary charge collecting regions. This extraction allows the signal charge collecting regions to maintain small area and low capacitance while still achieving high sensitivity through optimized electric field distribution.
3Measurement precision
If unnecessary charge collecting gate electrodes are added to block unnecessary charge, then charge transfer accuracy improves, but device complexity increases
Solution Approach 1:
The unnecessary charge collecting gate electrodes serve multiple functions: they block unnecessary charge from entering signal charge collecting regions, they collect unnecessary charge in dedicated regions, and they can be controlled through the existing charge transfer signal. This multi-functionality achieves improved measurement precision without proportionally increasing device complexity.
Solution Approach 2:
The patent merges the blocking function and collection function into a single electrode system. The unnecessary charge collecting gate electrodes simultaneously perform both the blocking of unnecessary charge paths and the collection of unnecessary charge in dedicated regions, reducing the overall complexity compared to having separate blocking and collection systems.
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 enables efficient charge transfer and enhanced sensitivity by optimizing the layout of signal and unnecessary charge collecting regions, ensuring accurate and rapid distance measurement.
Implementation Method 1
detect reflected light from the object with a photodetecting element
Implementation Method 2
an electric field established by the transfer electrodes and the signal charge collecting regions acts on the charge
Data Source
AI summary
A light receiving region has a planar shape of a rectangular shape having a pair of long sides opposed to each other in a first direction and a pair of short sides opposed to each other in a second direction. First and second semiconductor regions are arranged as spatially separated from each other along the respective long sides. First and second gate electrodes are arranged each between the corresponding semiconductor region and the light receiving region. Third gate electrodes are arranged as spatially separated from each other between the first and second gate electrodes arranged along the long sides. Each of the third gate electrodes has a first electrode portion located between a third semiconductor region and the light receiving region, and a second electrode portion overlapping with the light receiving region and having a width in the second direction smaller than that of the first electrode portion.