CMOS Image Sensor Noise Reduction via Dual-Mode Signal Control
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Solution Overview
Problem
In digital X-ray imaging, existing image sensors face challenges in achieving high signal-to-noise ratios due to noise entering circuit elements, requiring effective methods to extract signals while removing noise, especially in photoelectric conversion elements.
Innovation Solution
A control method and apparatus that utilize a driving method with two modes: a first mode for irrelevant information drive and a second mode for relevant information drive, with a transition to the second mode after a desired time, incorporating a flat panel sensor with a CMOS image sensor and a configuration that includes switching elements and sample hold circuits to manage light and noise signals effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If signals are extracted from photoelectric conversion elements while removing noise, then signal-to-noise ratio is improved, but device complexity increases due to additional circuit elements and control mechanisms
Solution Approach 1:
The patent divides the photoelectric conversion device into multiple independent photoelectric conversion elements, each with its own signal line and reset switch. This segmentation allows individual control and noise management for each element, improving signal-to-noise ratio while keeping each element's circuit relatively simple.
Solution Approach 2:
The patent applies reset potential to signal lines before light signal input occurs. This preliminary action clears noise from the signal lines in advance, ensuring that when the actual light signal arrives, the line is already prepared and noise-free, thereby improving signal-to-noise ratio without requiring complex real-time noise filtering circuits.
2Measurement precision
If reset potential is applied to light signal line and noise signal line, then signal output quality is improved, but energy consumption increases
Solution Approach 1:
The patent applies reset potential selectively to individual signal lines based on their specific noise conditions and signal requirements. Not all photoelectric conversion elements undergo reset processing simultaneously or with the same intensity, allowing energy to be applied locally where needed rather than uniformly across the entire device, thus improving signal quality while reducing overall energy consumption.
3Measurement precision
If image sensor with large area is used, then resolution and image quality are improved, but volume of imaging apparatus increases
Solution Approach 1:
The patent integrates multiple functional components (photoelectric conversion elements, signal lines, reset switches, and control circuits) into a compact layered structure where smaller components are nested within or adjacent to larger ones. This nesting approach allows a large-area image sensor to achieve high resolution while maintaining a compact overall apparatus volume by efficiently utilizing three-dimensional space.
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 enables the acquisition of high signal-to-noise ratio outputs by effectively managing noise in the imaging process, improving image quality and reducing distortion, while allowing for real-time observation of moving images.
Implementation Method 1
an image sensor having a large area in which photoelectric conversion elements are arranged in a matrix
Data Source
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AI summary
An imaging apparatus (100) including: a plurality of pixels including a photoelectric conversion element and a sample hold circuit; a plurality of signal lines configured to read from the plurality of pixels an electric signal held in the sample hold circuit therein; a imaging control means (109) configured to perform a first control for applying the held electric signal to the plurality of signal lines, and a second control for sequentially applying to the signal lines the electric signal obtained corresponding to light received by each of the plurality of pixels and reading the electric signal, after the first control has been performed; and a generation means configured not to create image data based on the electric signal applied to the signal line by the first control but to create the image data based on the electric signal read via the signal line by the second control.