Selectable Aiming Pattern for Imaging Bar Code Reader
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Solution Overview
Problem
Imaging-based bar code readers face challenges with parallax errors between aiming patterns and field of view, especially at varying target distances, leading to inaccurate aiming and poor resolution at near and far limits of the working range.
Innovation Solution
An aiming pattern assembly that generates multiple aiming patterns, with a light source assembly and pattern shaping element creating distinct patterns for near and far ranges, and a pattern selection assembly to selectively pass or block these patterns based on target distance, ensuring accurate alignment with the field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single aiming pattern is used for all target distances, then the device structure is simple, but parallax errors occur between the aiming pattern and field of view at varying distances
Solution Approach 1:
The working range is divided into multiple segments (near range and far range), with each segment having its own dedicated aiming pattern. The pattern shaping element includes multiple zones that generate different aiming patterns for different distance ranges, eliminating parallax errors by providing the appropriate pattern for each segment.
Solution Approach 2:
The aiming pattern assembly dynamically switches between different aiming patterns based on the detected target distance. The pattern selection assembly activates the appropriate aiming pattern for the current working range, making the system adaptive to varying distances and maintaining aiming accuracy throughout the entire working range.
2Measurement precision
If multiple aiming patterns are generated for different distances, then aiming accuracy is improved, but the device complexity increases
Solution Approach 1:
Multiple aiming patterns are generated within a single integrated pattern shaping element rather than using separate assemblies for each pattern. The light source assembly, pattern shaping element with multiple zones, and pattern selection assembly work together as one unified structure, reducing overall device complexity while providing multiple distance-specific aiming patterns.
Solution Approach 2:
The pattern shaping element serves multiple functions by containing multiple zones that generate different aiming patterns for different working ranges. This multi-functional design eliminates the need for separate aiming pattern generators, simplifying the overall device structure while maintaining the capability to provide accurate aiming for both near and far ranges.
3Device complexity
If the aiming pattern is offset from the imaging system, then the structure is simpler, but parallax error occurs between aiming pattern and field of view
Solution Approach 1:
Different zones within the pattern shaping element have different optical properties tailored to specific distance ranges. Each zone is designed with local quality characteristics that compensate for parallax at its intended working range, allowing the system to maintain alignment accuracy without requiring the entire aiming pattern assembly to be offset from the imaging system.
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 reduces aiming errors and improves resolution by providing congruent aiming patterns with the field of view across the working range, enhancing the user's ability to accurately aim the bar code reader at different distances.
Implementation Method 1
a light source assembly generating visible light
Implementation Method 2
a pattern shaping element receiving focused light from the light source assembly and including a first area and a non-overlapping second area, focused light passing through the first area creating a first aiming pattern projected toward the field of view
Data Source
AI summary
An aiming pattern assembly (60) for an imaging-based bar code reader (10) including: a light source assembly (62) generating focused light; a pattern shaping assembly (66) receiving focused light from the light source assembly (62) and including a first area (66a) and a non-overlapping second area (66b), focused light passing through the first area (66a) creating a first aiming pattern (P1) projected toward a field of view (FV) and passing through the second area (66b) creating a second aiming pattern (P2) projected toward the field of view (FV); and a pattern selection assembly (68) receiving the first and second aiming patterns (P1, P2) and passing at least one of the first and second aiming patterns (P1, P2).