Global Electronic Shutter for CMOS Image Sensor Blur Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
CMOS image readers using rolling shutters suffer from image distortion and image blur due to overlapping exposure periods and long exposure times, which are exacerbated by battery and illumination limitations.
Innovation Solution
A CMOS image reader with a global electronic shutter control circuitry that simultaneously exposes all pixels during an exposure period, coordinated with an illumination module to ensure adequate illumination, allowing for shorter exposure times and reduced distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If rolling shutter architecture is used to expose pixels sequentially, then device complexity is reduced, but image distortion and image blur occur due to overlapping exposure periods
Solution Approach 1:
The patent replaces the mechanical rolling shutter system with an electronic global shutter control mechanism. The electronic shutter simultaneously activates all pixels in the image sensor array at once, eliminating the sequential exposure mechanism that causes distortion. This substitution of mechanical sequential control with electronic simultaneous control resolves the contradiction by maintaining simpler device architecture while achieving sharp, distortion-free images.
2Illumination intensity
If long exposure times are used to capture sufficient light, then illumination intensity is improved, but image blur increases due to hand shake and subject movement
Solution Approach 1:
The patent changes the exposure time parameter from long duration to short duration by implementing global shutter control. The simultaneous exposure of all pixels allows the system to use shorter exposure times while still capturing sufficient light, thereby reducing motion blur and hand shake effects. This parameter change resolves the contradiction between light collection efficiency and image sharpness.
3Illumination intensity
If illumination source remains on during entire frame capture time, then illumination intensity is maintained, but energy consumption increases
Solution Approach 1:
The patent implements periodic illumination control where the illumination source is activated only during the specific exposure period of the global shutter, rather than remaining on continuously. This periodic operation synchronizes illumination with the simultaneous pixel exposure, reducing energy consumption while maintaining adequate illumination intensity during the critical capture moment.
4Device complexity
If sequential row exposure is used, then device complexity is reduced, but measurement precision deteriorates due to different exposure times for different rows
Solution Approach 1:
The patent merges the exposure control of all pixel rows into a single simultaneous exposure event. Instead of controlling each row sequentially with different timing, the global shutter mechanism combines all row exposures into one unified operation, ensuring all pixels capture light at the same moment. This merging of exposure control resolves the contradiction by maintaining manageable device complexity while significantly improving measurement precision.
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
The solution enables the capture of sharp, distortion-free images with reduced blur, even in low-light conditions, by synchronizing the exposure and illumination periods, thereby improving image quality and reducing the impact of environmental limitations.
Implementation Method 1
A CCD based image sensor contains an array of electrically coupled light sensitive photodiodes that convert incident light energy into packets of electric charge
Implementation Method 2
the light sources comprise light emitting diodes
Data Source
AI summary
The invention features a system and method to automatically focus an image reader using a single frame of image data. The method comprises exposing sequentially a plurality of rows of pixels in the image sensor. The method further comprising varying in incremental steps the focus of the image reader's optical system from a first setting where a distinct image of objects located at a first distance from the image reader is formed on the image sensor to a second setting where a distinct image of objects located at a second distance from the image reader is formed on the image sensor. As part of the method, the varying of the focus of the optical system occurs during the exposure of the plurality of rows of pixels.