Solid Imaging Device Overflow Gate Segmentation for Stepless Integration
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Solution Overview
Problem
Existing solid-state imaging devices cannot steplessly change the number of integration stages for exposure, limiting their sensitivity adjustment to varying light conditions.
Innovation Solution
The device incorporates an overflow gate with a predetermined electric resistance value and voltage application units connected at multiple points, allowing the barrier level to be adjusted, enabling stepless change in the number of integration stages by controlling voltage across these points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the barrier levels of overflow gates are fixed at manufacture, then the device structure is simple, but the number of integration stages cannot be changed steplessly
Solution Approach 1:
The overflow gate is divided into multiple segments with separate voltage control terminals. Each segment can have its barrier level independently adjusted, enabling stepless change of integration stages while maintaining a relatively simple overall structure.
Solution Approach 2:
The barrier levels of the overflow gate are changed from fixed to dynamically adjustable. By applying different voltages to the segmented overflow gate, the integration stages can be continuously varied according to imaging requirements.
2Adaptability or versatility
If all stages are provided with terminals for feeding transfer signals to enable stepless integration stage change, then the adaptability is improved, but the device structure becomes unpractical
Solution Approach 1:
Instead of providing terminals at all stages, the overflow gate is segmented into a limited number of control regions. This reduces the terminal count to a practical level while still enabling effective control of charge flow and integration stage adjustment.
Solution Approach 2:
The segmented overflow gate structure serves multiple functions: it controls charge overflow, adjusts integration stages steplessly, and maintains TDI transfer functionality, reducing the need for separate control mechanisms at each stage.
3Reliability
If barrier levels are lowered in earlier stage part, then saturation is suppressed, but the number of integration stages cannot be flexibly adjusted
Solution Approach 1:
Different segments of the overflow gate have different voltage control characteristics, creating local variations in barrier levels. This allows saturation suppression in specific regions while maintaining adjustable integration stages across the entire device.
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 allows for continuous adjustment of the number of integration stages, enhancing sensitivity by ensuring that only relevant electric charges are transferred, preventing overflow and saturation.
Implementation Method 1
the overflow gate has a predetermined electric resistance value, while the voltage application unit is electrically connected to the overflow gate at a plurality of connecting parts
Implementation Method 2
photoelectric conversion units, so that exposure is integrated by the number of vertical stages of pixels
Data Source
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AI summary
In a solid-state imaging device 1, an overflow gate (OFG) 5 has a predetermined electric resistance value, while voltage application units 16, to 165 are electrically connected to the OFG 5 at connecting parts 171 to 175. Therefore, when voltage values V1 to V5 applied to the connecting parts 171 to 175 by the voltage application units 161 to 165 are adjusted, the OFG 5 can yield higher and lower voltage values in its earlier and later stage parts, respectively. As a result, the barrier level (potential) becomes lower and higher in the earlier and later stage parts, so that all the electric charges generated in an earlier stage side region of photoelectric conversion units 2 can be caused to flow out to an overflow drain (OFD) 4, whereby only the electric charges generated in a later stage side region of the photoelectric conversion units 2 can be TDI-transferred.