Pixel-Sharing Image Sensor Layout for Stronger Transistor Drive
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Solution Overview
Problem
In solid-state imaging elements with a pixel sharing type structure, the sharing of transistors among pixels leads to insufficient driving force due to narrow transistor gate widths, which affects optical characteristics like sensitivity, especially as pixel size decreases with miniaturization.
Innovation Solution
The implementation of a configuration where multiple transistors are connected in parallel and arranged in specific directions to enhance driving force, including amplification, selection, and reset transistors, while maintaining light receiving area sizes, and incorporating symmetrical transistor arrangements to improve photo response non-uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If transistors are shared among multiple pixels to reduce the number of transistors per pixel, then the light receiving area can be increased, but the transistor gate width becomes narrow resulting in insufficient driving force
Solution Approach 1:
The patent combines multiple transistors (first transistor and second transistor) in parallel to share the driving load. This merging approach allows the light receiving area to remain large while the combined transistor structure provides sufficient driving force, resolving the contradiction between area and power.
Solution Approach 2:
The patent segments the transistor function into multiple parallel transistors instead of using a single large transistor. This segmentation allows each transistor to have a manageable gate width while collectively providing the required driving force for the shared pixel group.
2Power
If the gate width of the transistor is increased to improve driving force, then the sensitivity improves, but the light receiving area must be reduced
Solution Approach 1:
The patent merges multiple transistors in parallel configuration where the first transistor and second transistor work together to provide the necessary driving force. This combination achieves the required power output without requiring any single transistor to have a large gate width that would encroach on the light receiving area.
3Productivity
If miniaturization is progressed to reduce pixel size, then the device density increases, but the transistor driving force becomes even more insufficient
Solution Approach 1:
The patent applies the merging principle by combining multiple transistors in parallel within each pixel group. This allows miniaturization to proceed while maintaining sufficient driving force through the collective action of the parallel transistor network, effectively decoupling device density from driving force adequacy.
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 improves the driving force of transistors, enhances image quality by maintaining light receiving areas, and reduces the number of wires needed, thereby addressing the issue of insufficient driving force and sensitivity in pixel sharing type solid-state imaging elements.
Implementation Method 1
a plurality of first photoelectric conversion elements; a first transfer section configured to transfer electric charge from the plurality of first photoelectric conversion elements to the first electric charge accumulating section
Data Source
AI summary
A solid-state imaging element of a pixel sharing type with improved driving of transistors is disclosed. A first electric charge accumulating section and a second electric charge accumulating section are arranged in a predetermined direction. A first transfer section transfers electric charge from first photoelectric conversion elements to the first electric charge accumulating section, causing it to accumulate the electric charge. A second transfer section transfers electric charge from second photoelectric conversion elements to the second electric charge accumulating section, causing it to accumulate the electric charge. A first transistor is configured to output a signal corresponding to an amount of the electric charge accumulated in each of the first electric charge accumulating section and the second electric charge accumulating section. A second transistor is arranged with the first transistor in the predetermined direction and connected in parallel to the first transistor.