Imaging Pixel Signal Holding Unit for Phase Contrast Detection
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Solution Overview
Problem
Existing imaging apparatuses face challenges in performing phase contrast detection type focal point detection at the imaging face due to inadequate pixel configurations, leading to issues with noise signal removal and dark current generation, which affect the precision and accuracy of the detection process.
Innovation Solution
The implementation of a configuration with distinct pixel types for imaging and focal point detection, including a signal holding unit between the photoelectric conversion unit and amplification element, allows for phase contrast detection and global electronic shutter operation with reduced noise, utilizing different aperture sizes and light-shielding members to enhance signal holding and noise removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If charges are transferred to floating diffusion for signal holding, then readout timing can be aligned (global electronic shutter), but dark current increases during the holding period
Solution Approach 1:
The pixel is divided into distinct functional regions: a photoelectric conversion unit for charge generation, a signal holding unit for charge storage, and a floating diffusion for readout. This segmentation allows charges to be held in the signal holding unit during the exposure period, preventing dark current accumulation in the floating diffusion while maintaining global electronic shutter functionality.
Solution Approach 2:
A transfer switch is introduced as an intermediary element between the photoelectric conversion unit and the floating diffusion. This transfer switch enables controlled charge transfer timing, allowing charges to be moved from the photoelectric conversion unit to the signal holding unit first, then to the floating diffusion at the appropriate readout time, thereby minimizing dark current generation.
2Measurement precision
If multiple rows of circuits are added to hold noise signals in column circuits, then noise removal precision improves, but device area increases
Solution Approach 1:
The noise signal holding function is extracted from the column circuits and relocated to dedicated noise holding units within each pixel. This extraction eliminates the need for additional row circuits in the column, reducing the overall device area while maintaining the capability to hold and remove noise signals effectively.
Solution Approach 2:
Instead of expanding the noise holding capability horizontally across multiple circuit rows in the column, the solution moves vertically by integrating noise holding units within each pixel structure. This dimensional reorganization allows noise signal holding to occur at the pixel level rather than requiring additional column circuit rows, thereby reducing device area.
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 enables precise phase contrast detection and focal point detection with low noise, improving the accuracy and efficiency of the imaging process by effectively managing dark current and noise signals, thereby enhancing the overall performance of the imaging apparatus.
Implementation Method 1
a plurality of pixels each including a photoelectric conversion unit
Data Source
AI summary
An imaging apparatus includes a plurality of pixels, a signal holding unit, first and second control electrodes. Each of the plurality of pixels includes a photoelectric conversion unit, and an amplification element to amplify signals based on signal charges generated by the photoelectric conversion unit, in which the plurality of pixels output signals for performing a phase contrast detection type of focal point detection. The signal holding unit is in an electrical pathway between an output node of the photoelectric conversion unit and an input node of the amplification element, in which signals for performing the phase contrast detection type of focal point detection are held. The first control electrode is configured to transfer a signal of the photoelectric conversion unit to the signal holding unit. The second control electrode is configured to transfer a signal for performing the phase difference detection type of focal point detection.