Range Image Sensor Aperture Ratio via Segmented Electrodes
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Solution Overview
Problem
Conventional range image sensors have a low aperture ratio due to the perimeter of the charge generating region being surrounded by discharge gate electrodes, which affects the sensor's performance in distance measurement accuracy and signal-to-noise ratio.
Innovation Solution
The range image sensor design features signal charge collecting regions and unnecessary charge collecting regions arranged opposite to each other with transfer electrodes in between, allowing for improved aperture ratio and efficient charge transfer without surrounding the photosensitive region, thus enhancing the signal-to-noise ratio and allowing for a high-speed charge transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discharge gate electrodes are arranged to surround the charge generating region, then background light charges can be discharged and dynamic range increases, but the aperture ratio decreases
Solution Approach 1:
The discharge gate electrodes are segmented into multiple regions: first discharge gate electrodes arranged along the first direction and second discharge gate electrodes arranged along the second direction. This segmentation allows selective discharge of background light charges while minimizing the area occupied by electrodes, thereby improving aperture ratio while maintaining dynamic range.
Solution Approach 2:
The patent introduces a two-dimensional arrangement of discharge gate electrodes with different orientations (first direction and second direction). This dimensional approach allows the electrodes to discharge background light charges from multiple directions without completely surrounding the charge generating region, thus improving aperture ratio while maintaining the ability to discharge background light charges effectively.
2Productivity
If transfer electrodes and unnecessary charge collecting gate electrodes are arranged to surround the photosensitive region, then charge transfer can be achieved, but the aperture ratio is reduced
Solution Approach 1:
The charge transfer function is segmented between transfer electrodes and unnecessary charge collecting gate electrodes, which are positioned at different locations and oriented in different directions. This segmentation allows efficient charge transfer without requiring complete surrounding of the photosensitive region, thereby improving aperture ratio while maintaining charge transfer speed.
Solution Approach 2:
The unnecessary charge collecting gate electrodes act as intermediaries that collect and remove unnecessary charges (such as background light charges) without interfering with the primary charge transfer function of the transfer electrodes. This intermediary function allows the transfer electrodes to operate efficiently while the unnecessary charge collecting gate electrodes maintain a less intrusive arrangement, improving aperture ratio.
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 significantly improves the aperture ratio and ensures a high signal-to-noise ratio in the range image sensor, enabling accurate distance measurement and improved range image acquisition.
Implementation Method 1
detect reflected light from the object with a photodetecting element, and thereby to output a signal according to the distance to the object
Implementation Method 2
transfer gate electrodes provided respectively along a pair of two opposed sides of the charge generating region, floating drain regions for accumulating respective signal charges transferred by the transfer gate electrodes
Data Source
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AI summary
A range image sensor RS is provided with an imaging region consisting of a plurality of units arranged in a two-dimensional pattern, on a semiconductor substrate 1 and obtains a range image, based on charge quantities output from the units. One unit is provided with a photosensitive region, a plurality of third semiconductor regions 9a, 9b opposed to each other with a photogate electrode PG in between in a direction in which first and second long sides L1, L2 are opposed to each other, first and second transfer electrodes TX1, TX2 provided between the plurality of third semiconductor regions 9a, 9b and the photogate electrode PG, a plurality of fourth semiconductor regions 11 a, 11b arranged with the third semiconductor regions 9a, 9b in between in the direction in which the first and second long sides L1, L2 are opposed to each other, and a plurality of third transfer electrodes TX3 provided respectively between the plurality of fourth semiconductor regions 11a, 11b and the photogate electrode PG.