Solid State Imaging Device Photosensitive Region Charge Drain
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Solution Overview
Problem
Existing solid state imaging devices face challenges in enhancing sensitivity to incident light and extending the charge accumulation period while maintaining efficient charge drainage, as enlarging photosensitive regions either lengthens charge transfer distance or slows down the charge drain process.
Innovation Solution
The device features photosensitive regions with a planar shape extending along long sides, utilizing a potential gradient forming portion with two regions to transfer charges to short sides for rapid drainage, allowing for a longer charge accumulation period and improved sensitivity by arranging charge drain portions correspondingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the photosensitive region is enlarged by lengthening the edge on the side where the charge output portion is arranged, then the sensitivity to incident light is improved, but the charge transfer distance becomes longer and the charge drain period cannot be shortened
Solution Approach 1:
The invention divides the charge transfer path into two separate directions by providing first and second charge transfer portions extending in different directions from the photosensitive region. This segmentation allows charges to be transferred simultaneously in multiple directions, reducing the overall transfer distance and time while maintaining a large photosensitive region area for high sensitivity.
Solution Approach 2:
The invention transitions from a single-direction charge transfer path to a two-dimensional charge transfer network by arranging charge transfer portions in multiple directions (first direction and second direction). This dimensional expansion enables parallel charge transfer paths, effectively reducing the charge transfer distance without compromising the photosensitive region size.
2Length of moving object
If the photosensitive region is enlarged by lengthening the edge on the side where the charge drain portion is arranged, then the charge transfer distance can be kept short, but the charge drain portion becomes slower and the charge drain period cannot be shortened
Solution Approach 1:
The invention segments the charge drain function into multiple charge drain portions positioned at different locations and orientations relative to the photosensitive region. This segmentation enables parallel charge drainage operations, increasing the overall charge drain speed while keeping the photosensitive region compact for short transfer distances.
Solution Approach 2:
The invention combines multiple charge transfer portions and charge drain portions into an integrated structure that operates simultaneously. The first and second charge transfer portions work in parallel with their respective charge drain portions, merging multiple drainage paths into a unified high-speed charge drain system.
3Illumination intensity
If the photosensitive region is enlarged, then the sensitivity to incident light is improved, but the charge accumulation period cannot be set longer due to increased charge drain time
Solution Approach 1:
The invention segments the charge handling system into multiple parallel transfer and drain paths, enabling simultaneous charge transfer and drainage operations. This segmentation reduces the total charge drain time, allowing for longer charge accumulation periods even with enlarged photosensitive regions that generate more charge.
Solution Approach 2:
The invention enables continuous charge accumulation by implementing parallel charge transfer and drain operations. While charges are being accumulated in the photosensitive region, other charges can be simultaneously transferred and drained through the parallel paths, ensuring uninterrupted operation and enabling longer accumulation periods.
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 enhances light sensitivity and enables a longer charge accumulation period while maintaining a short charge drainage period, improving the overall performance of the solid state imaging device.
Implementation Method 1
a potential gradient forming portion (3) having a first potential gradient forming region (3a) to form a potential gradient becoming lower along the second direction from the electrode (15a) to the electrode (16)... a second potential gradient forming region (3b) to form a potential gradient becoming higher from the electrode (16) to the electrode (15b)
Data Source
Figure 1
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AI summary
A solid state imaging device 1 is provided with a photoelectric conversion portion 2 having photosensitive regions 13, and a potential gradient forming portion 3 arranged opposite to the photosensitive regions 13. A planar shape of each photosensitive region 13 is a substantially rectangular shape composed of two long sides and two short sides. The photosensitive regions 13 are juxtaposed in a first direction intersecting with the long sides. The potential gradient forming portion 3 has a first potential gradient forming region to form a potential gradient becoming lower along a second direction from one of the short sides to the other of the short sides, and a second potential gradient forming region to form a potential gradient becoming higher along the second direction. The second potential gradient forming region is arranged next to the first potential gradient forming region in the second direction.