Solid-State Image Sensor Offset Signal Separation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional image sensing devices experience a narrowing of the dynamic range of image data when performing resolution conversion due to the addition of offset signals caused by dark current, which degrades image quality and SN ratio.
Innovation Solution
A solid-state image sensing device is designed with a photoelectric conversion unit, a signal separation unit to remove offset signals, and a signal adding or averaging unit that processes image signals for groups of pixels, preventing the inclusion of offset signals in the dynamic range during resolution conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pixel signals including offset signals are added for resolution conversion, then the image reading rate is increased and the size of read image data is reduced, but the dynamic range of image data is narrowed
Solution Approach 1:
The patent segments the pixel signals into two distinct components: offset signals (caused by dark current) and image signals (actual light information). By separating these components before addition, the system can process them differently - offset signals are handled to prevent dynamic range narrowing, while image signals are added for resolution conversion. This segmentation resolves the contradiction by allowing both high reading rate and preserved dynamic range.
Solution Approach 2:
The patent extracts and removes offset signals from the pixel signals before performing addition for resolution conversion. By taking out the harmful offset component and processing only the pure image signals, the system achieves resolution conversion without narrowing the dynamic range. This extraction principle directly addresses the contradiction by eliminating the source of the problem while maintaining the beneficial resolution conversion effect.
2Use of energy by moving object
If pixel signals including offset signals are added for resolution conversion, then the amount of light emission from reading light source is reduced, but the dynamic range of image data is narrowed
Solution Approach 1:
The patent segments the pixel signals into offset signals and image signals, allowing the system to reduce light emission (and thus power consumption) while maintaining dynamic range. By separating the signal components, the system can operate at lower light levels without the offset signals degrading the dynamic range of the resulting image data.
Solution Approach 2:
The patent extracts offset signals from the total pixel signals, enabling the system to use reduced light emission for power saving while preserving dynamic range. By removing the offset component that would otherwise consume dynamic range, the system can operate energy-efficiently without sacrificing image data quality.
3Productivity
If resolution conversion is performed by adding pixel data, then the line period is shortened and productivity is enhanced, but the output level of the image sensor decreases
Solution Approach 1:
The patent segments the pixel signals to separate offset and image components, enabling resolution conversion through addition while maintaining output level. By processing only the image signal portion (without offset signals) during addition, the system achieves shortened line periods for enhanced productivity without the output level degradation that would result from adding offset signals.
Solution Approach 2:
The patent extracts offset signals from the pixel data before addition operations, allowing resolution conversion that shortens the line period and enhances productivity. By removing the offset component, the system maintains the output level of the image sensor while achieving the productivity benefits of resolution conversion.
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 solution effectively prevents the narrowing of the dynamic range, enhancing image quality and SN ratio while allowing for resolution conversion without degrading image data, and reduces circuit complexity by separating offset signals after digital conversion.
Implementation Method 1
a photoelectric conversion unit that converts light into electrical signals for respective pixels and outputs the electrical signals
Data Source
AI summary
A solid-state image sensing device includes: a photoelectric conversion unit that converts light into electrical signals for respective pixels and outputs the electrical signals; a signal separation unit that separates an offset signal, which is generated due to dark current, from each of the electrical signals outputted by the photoelectric conversion unit and outputs image signals which are electrical signals converted from light for the respective pixels; and a signal adding unit that adds the image signals, which is outputted from the signal separation unit, for each group of a plurality of pixels.