Imaging Reader Exposure Control for Varying Light Intensity
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Solution Overview
Problem
Imaging readers face challenges in capturing and decoding symbols with varying light intensity levels, as a single exposure control setting cannot reliably handle shadows and highlights, leading to unsuccessful image processing.
Innovation Solution
The imaging reader employs a controller to successively expose the imager with different exposure time periods for areas with different light intensity levels, using a combination of shorter and longer exposure times to capture shadows and highlights separately and then combine these images through averaging or region of interest analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single exposure control setting is used for the imager, then the device complexity is reduced, but the ability to capture symbols with varying light intensity levels (shadows and highlights) deteriorates
Solution Approach 1:
The patent segments the exposure process into multiple distinct exposure time periods (first exposure time period and second exposure time period) to capture different light intensity regions separately. This allows the imager to capture both shadows and highlights without requiring multiple separate imaging devices or complex post-processing, thereby improving reliability while maintaining manageable complexity
Solution Approach 2:
The patent dynamically adjusts the exposure time periods based on the detected light intensity levels in different regions of the symbol. The controller selectively applies different exposure times to different areas, making the exposure control adaptive rather than static. This dynamic approach enables reliable capture of varying light conditions without requiring a completely complex fixed system
2Illumination intensity
If the exposure time is extended to capture shadows, then the visibility of dark areas improves, but the highlights become overexposed and clipped
Solution Approach 1:
The patent divides the imaging process into separate exposure phases: a first exposure time period optimized for capturing shadow regions and a second exposure time period optimized for capturing highlight regions. By segmenting the exposure process, each phase can be optimized for its specific purpose without compromising the other, preventing highlight clipping while maintaining shadow visibility
Solution Approach 2:
The patent changes the exposure time parameter dynamically based on the imaging requirements. The controller selects different exposure time periods (first and second exposure time periods) corresponding to different light intensity levels. This parameter adjustment allows the system to adapt to varying lighting conditions and capture accurate images without overexposure or underexposure in any region
3Illumination intensity
If the exposure time is reduced to capture highlights, then the brightness of light areas improves, but the shadows become too dark to capture
Solution Approach 1:
The patent segments the exposure process into distinct temporal phases where the first exposure time period is dedicated to capturing shadow regions with extended exposure, while the second exposure time period captures highlight regions with reduced exposure. This segmentation allows each region to receive optimal exposure timing, preventing shadow darkness while maintaining highlight brightness
Solution Approach 2:
The patent dynamically changes the exposure time parameter to match the lighting conditions of different regions. The controller selects appropriate exposure time periods based on the detected light intensity levels, extending exposure for shadow regions and reducing it for highlight regions. This adaptive parameter change ensures both shadows and highlights are captured within the imager's dynamic range
4Reliability
If multiple exposure time periods are used to capture different light intensity levels, then the symbol reading reliability improves, but the imaging time increases
Solution Approach 1:
The patent employs periodic exposure cycles where the imager alternates between first and second exposure time periods in a structured sequence. The controller manages these periodic exposures to capture different light intensity levels systematically. By organizing the imaging process into periodic phases rather than continuous scanning, the system achieves reliable multi-level capture with controlled time expenditure
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 successful decoding of symbols with both shadows and highlights, improving symbol reading performance by optimizing exposure settings for varying light conditions.
Implementation Method 1
an imaging lens assembly for capturing return light scattered and/or reflected from the symbol being imaged
Implementation Method 2
capturing return light scattered and/or reflected from the symbol being imaged
Implementation Method 3
the illuminating light assembly includes one or more light emitting diodes (LEDs) for emitting the illumination light
Data Source
AI summary
An arrangement for, and a method of, controlling image exposure in an imaging reader for reading symbols, employ an illuminating light assembly for illuminating a symbol with illumination light, a solid-state imager for capturing return light from the symbol over a field of view, and a controller for successively exposing the imager over a first exposure time period to capture the return light from, and to optimally image, a first area of the symbol, and over a second exposure time period to capture the return light from, and to optimally image, a second area of the symbol. The first and the second areas have different light intensity levels. The first and the second exposure time periods are different in duration. The controller is operative for combining the optimally imaged first and second areas to read the symbol.