Imaging Device Charge Splitting for Environmental Light Interference
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Solution Overview
Problem
Conventional imaging devices face challenges in accurately recognizing objects under varying natural environmental light conditions, particularly due to interference from sunshine, which affects the charge transfer efficiency and accuracy of distance measurement.
Innovation Solution
The imaging device employs a light source emitting light in a given cycle, with a pixel unit array for photoelectric conversion, including a charge transfer portion and separate charge storage regions for charges generated during illumination by the light source and environmental light. A differential circuit extracts and measures the difference between charges, allowing for image generation without environmental light interference and enabling distance calculation based on phase differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light source emits light at a high ratio to improve recognition performance, then the quantity of charge sampled decreases, but recognition performance is improved
Solution Approach 1:
The photoelectric conversion portion is divided into multiple regions (first photoelectric conversion region and second photoelectric conversion region) that are spatially separated. This segmentation allows different regions to collect charges from different light sources (artificial light and environmental light respectively), enabling the system to maintain high recognition performance while preserving sufficient charge quantity for accurate measurement
Solution Approach 2:
A transfer gate is introduced as an intermediary component between the photoelectric conversion portions and the charge storage portions. This transfer gate controls the timing and path of charge transfer, allowing charges to be selectively transferred to different storage regions based on the light emission timing, thereby resolving the conflict between charge quantity and recognition performance
2Adaptability or versatility
If environmental light is present during imaging, then charge transfer efficiency decreases, but the imaging device can operate in natural conditions
Solution Approach 1:
The light source operates in periodic pulses, and the imaging device synchronizes its charge transfer operations with these pulses. By transferring charges only during the periods when the light source is emitting (and not during environmental light periods), the system maintains high charge transfer efficiency while still being able to operate in natural environmental conditions
Solution Approach 2:
The first photoelectric conversion region is designed to collect charges during the period before environmental light interference occurs. By preliminarily collecting these charges and storing them in a dedicated charge storage region, the system ensures accurate distance measurement is performed before environmental light degrades the charge transfer efficiency
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 solution effectively eliminates the influence of environmental light, improving the accuracy of image generation and distance measurement by enhancing charge transfer efficiency and reducing interference from background light.
Implementation Method 1
a light receiving portion having a pixel unit array for photoelectric conversion for light received from a view
Implementation Method 2
a charge transfer portion connected to each of photoelectric conversion portions in the light receiving portion, a first charge storage region for receiving charge generated in the photoelectric conversion portions during the first period via the charge transfer portion
Data Source
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AI summary
Charge generated in a photodiode is properly split for difference processing. An imaging element is constituted by a semiconductor such that a charge accumulation portion is connected to a light receiving portion using a buried photodiode and charge is split from the charge accumulation portion by a plurality of gates and is accumulated. An imaging device includes a control device performing control so as to accumulate charge that is generated by a photoelectric conversion at an exposure cycle synchronous with the light emission of a light source. The exposure cycle includes a first period for receiving reflection light from a subject illuminated by light from the light source and a second period for receiving light from the subject illuminated by an environmental light not including the light from the light source. The imaging device includes a charge accumulation region connected to each photoelectric conversion region, a first charge storage region for receiving charge generated in the photoelectric conversion regions during the first period via the charge accumulation portion, and a second charge storage region for receiving charge generated in the photoelectric conversion regions during the second period via the charge accumulation portion.