Solid-State Imaging Device Charge Readout Sequence
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Solution Overview
Problem
In high dynamic range imaging, the existing techniques face issues with reading out charges from solid-state imaging devices, where the potential of the P-type pixel substrate becomes positive due to parasitic capacitance, affecting the electric field and leading to incomplete transfer of electrons, resulting in image quality deterioration and afterimages.
Innovation Solution
A solid-state imaging device with a photodiode that stores a first charge and a second charge in separate capacitors, where the driving control unit outputs the signal from the second charge capacitor before the first charge, ensuring a satisfactory electric field for electron transfer and reducing residual electrons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If holes are stored in the hole storage capacitor during electron signal readout, then high dynamic range imaging is achieved, but the P-type pixel substrate potential becomes positive causing incomplete electron transfer
Solution Approach 1:
The patent applies preliminary action by resetting the P-type pixel substrate potential to 0V before electron transfer begins. This is achieved by controlling the pixel ground to maintain 0V potential during the electron transfer phase, preventing the positive potential buildup that would otherwise occur from hole storage. This preliminary potential stabilization ensures complete electron transfer while maintaining the capability for high dynamic range imaging through sequential readout of electrons and holes.
2Adaptability or versatility
If the P-type pixel substrate is controlled to be electrically floating during electron readout, then hole storage is enabled, but parasitic capacitance coupling causes further positive potential change
Solution Approach 1:
The patent introduces an intermediary control mechanism by using a dedicated pixel ground electrode that acts as a mediator between the hole storage capacitor and the P-type pixel substrate. This pixel ground is specifically controlled to maintain 0V potential during electron transfer, decoupling the parasitic capacitance effects from the substrate potential. The intermediary pixel ground allows hole storage to proceed while preventing parasitic coupling from affecting the substrate potential, thus maintaining both hole storage capability and potential control accuracy.
3Ease of operation
If positive voltage pulse is applied to transfer gate to readout electrons, then electron signal readout is enabled, but potential barrier forms in transfer transistor channel
Solution Approach 1:
The patent applies equipotentiality by maintaining the P-type pixel substrate at 0V potential during electron transfer, creating a uniform potential environment that eliminates potential barriers in the transfer transistor channel. By controlling the pixel ground to match the substrate potential at 0V, the patent ensures that no additional potential barriers form when the transfer gate voltage pulse is applied. This equipotential approach enables reliable electron signal readout while maintaining high transfer efficiency, resolving the contradiction between ease of operation and transfer reliability.
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 approach allows for effective readout of charges generated by photoelectric conversion, improving image quality by preventing afterimages and enhancing the signal-to-noise ratio.
Implementation Method 1
a pixel having a photodiode that performs photoelectric conversion on incident light
Data Source
AI summary
The present technology relates to a solid-state imaging device, a method of driving the same, and an electronic apparatus. The solid-state imaging device includes a pixel having a photodiode that performs photoelectric conversion on incident light, and a driving control unit configured to control driving of the pixel. The pixel stores a first charge generated by the photoelectric conversion in the photodiode and stores a second charge generated by the photoelectric conversion in a first capacitor provided in a pixel separation portion. The driving control unit causes a pixel signal due to the second charge stored in the first capacitor to be output and then a pixel signal due to the first charge stored in the photodiode to be output. The present technology may be applied, for example, to a solid-state imaging device or the like that detects both electrons and holes to perform high dynamic range imaging.