Rolling Shutter Aiming Light Control for Image Overexposure
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Solution Overview
Problem
Existing image readers with rolling shutter exposure mode face challenges in avoiding partial overexposure due to the aiming pattern projected by the aiming light source, as the exposure time of pixels is not synchronized, preventing the use of blanking technology.
Innovation Solution
A scanning system and method that control the aiming light source by turning it off during the exposure time of effective pixels and turning it on during at least part of the exposure time of non-imaging pixels, ensuring the aiming pattern does not interfere with image capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the aiming light source is kept on continuously to provide aiming guidance, then the aiming function is improved, but the image quality deteriorates due to partial overexposure
Solution Approach 1:
The aiming light source is controlled to operate periodically rather than continuously. It is turned on during the exposure periods of non-imaging pixels and turned off during the exposure periods of effective pixels. This periodic switching enables the system to provide aiming guidance when needed while preventing overexposure during critical image capture moments.
Solution Approach 2:
The system dynamically adjusts the aiming light source based on the rolling shutter exposure timeline. The control unit synchronizes the aiming light source switching with the sequential exposure of different pixel rows, making the aiming light source state dynamic rather than static. This dynamic control allows the system to adapt to different exposure phases and avoid overexposure while maintaining aiming functionality.
2Manufacturing precision
If the aiming light source is turned off during effective pixel exposure to avoid overexposure, then image quality is improved, but the aiming guidance availability deteriorates
Solution Approach 1:
The aiming light source operates in periodic cycles that align with the rolling shutter exposure pattern. By turning on the aiming light during non-imaging pixel exposure and turning it off during effective pixel exposure, the system maintains aiming guidance availability for portions of the cycle while ensuring image quality during critical capture periods.
Solution Approach 2:
The system discards the aiming light function during effective pixel exposure to protect image quality, and recovers it during non-imaging pixel exposure to maintain guidance availability. This cyclical discarding and recovering of the aiming function allows the system to prioritize image quality when needed while maintaining overall guidance availability.
3Manufacturing precision
If blanking technology is used to stagger the opening time of the aiming light source and exposure time, then overexposure is avoided, but this technology cannot be applied to rolling shutter exposure due to unsynchronized pixel exposure
Solution Approach 1:
The system adapts the blanking concept to rolling shutter exposure by making the aiming light source control dynamic and synchronized with the sequential exposure of different pixel rows. Instead of a simple global blanking approach, the system dynamically switches the aiming light source on and off based on which pixel rows are currently being exposed, making the technique applicable to rolling shutter architectures.
Solution Approach 2:
The pixel array is segmented into effective pixels and non-imaging pixels with different exposure timing requirements. The aiming light source control is segmented to match this division, being turned off during effective pixel exposure and turned on during non-imaging pixel exposure. This segmentation allows the blanking concept to be applied selectively to different portions of the pixel array.
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 effectively avoids partial overexposure of images captured by rolling shutter image readers, improving reading efficiency by ensuring the aiming pattern does not affect the image quality.
Implementation Method 1
an image sensor for sequentially exposing a pixel array through a rolling shutter to acquire an image of a target
Implementation Method 2
an aiming light source for projecting an aiming pattern to aim at the target
Data Source
AI summary
A scanning system and method for controlling an aiming light source (7), comprising: an image sensor (4), which sequentially exposes a pixel array through a rolling shutter to acquire an image of the target, the pixel array includes effective pixels (5) and non-imaging pixels (6), the effective pixels (5) are pixels that are actually used for image decoding, and the non-imaging pixels (6) are pixels that are not actually used for image decoding; an aiming light source (7) for projecting an aiming pattern (8) to aim at a target; a control unit (12) for controlling the image sensor (4) and the aiming light source (7), so that the aiming light source (7) is in turned off state during the exposure time of the effective pixel (5), and the aiming light source (7) is turned on during at least part of the exposure time of the non-imaging pixels (6).