Compact Imaging Module Lightpipe Aiming Pattern Adjustment
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Solution Overview
Problem
In compact imaging modules, the aiming light pattern often offsets from the imaging field of view, especially at increased working distances, making it difficult to achieve efficient reading performance, particularly with one-dimensional image sensors, and existing solutions like moving the aiming lens are constrained by space and can degrade focusing.
Innovation Solution
A support assembly with a lightpipe and movable chassis parts allows for spatial adjustment of the aiming light pattern to overlap the imaging field of view, using total internal reflecting surfaces to shape the aiming beam and maintain focusing, enabling independent or simultaneous adjustment of the aiming pattern and focusing within a miniaturized module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the aiming light assembly is mounted close to the image sensor in a compact imaging module, then the module size is reduced, but the aiming light pattern offsets from the imaging field of view, especially at increased working distances
Solution Approach 1:
A lightpipe is introduced as an intermediary optical element between the aiming laser and the target. The lightpipe receives the aiming beam from the laser and projects it to form the aiming light pattern on the target. This mediator allows decoupling the aiming light generation from direct line-of-sight projection, enabling the aiming pattern to be aligned with the imaging field of view even when the laser is positioned close to the image sensor in a compact module configuration
Solution Approach 2:
The optical path is folded using total internal reflecting surfaces within the lightpipe, changing the spatial dimension of light propagation. Instead of a direct linear path from laser to target, the beam undergoes multiple reflections inside the lightpipe, effectively extending the optical path length within a compact physical footprint. This dimensional transformation allows the aiming pattern to be properly positioned relative to the imaging field of view while maintaining a small module size
2Measurement precision
If the aiming lens is moved to steer the aiming pattern to overlap the imaging field of view, then the alignment is improved, but the focusing of the aiming light is degraded and space is consumed
Solution Approach 1:
The lightpipe serves as a mediator that replaces the need for moving the aiming lens to steer the pattern. By introducing this intermediate optical element with total internal reflecting surfaces, the aiming beam can be redirected to overlap with the imaging field of view without altering the position or focus settings of the original aiming lens, thereby maintaining focusing precision while achieving proper alignment
Solution Approach 2:
The optical system is segmented into separate functional components: the aiming laser generates the beam, the lightpipe with its total internal reflecting surfaces steers and shapes the beam, and the imaging lens independently handles the imaging function. This segmentation allows each component to be optimized for its specific function without compromising the other, maintaining aiming light focusing while achieving pattern alignment
3Device complexity
If a one-dimensional image sensor with only one pixel tall is used, then the device complexity is reduced, but even a few millimeters of offset cannot be tolerated for efficient reading performance
Solution Approach 1:
The lightpipe acts as a precise optical intermediary that ensures the aiming light pattern is accurately aligned with the single-pixel-tall imaging sensor. By controlling the projection geometry through total internal reflection, the system can maintain sub-millimeter alignment precision, making efficient reading performance achievable even with the simplified one-dimensional sensor configuration
Solution Approach 2:
The optical parameters of the lightpipe (such as the angles of total internal reflection and the geometry of the optical path) are specifically designed and adjusted to compensate for the limited tolerance of the one-dimensional sensor. By optimizing these parameters, the aiming pattern is projected with precise alignment to the imaging field of view, enabling efficient reading performance despite the simplified sensor architecture
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 adjusts the aiming light pattern to align with the imaging field of view, improving reading performance by minimizing offset issues and maintaining focusing, even in space-limited applications, thereby enhancing the accuracy and efficiency of target reading.
Implementation Method 1
a lightpipe for optically modifying the aiming beam to generate and shape an aiming light pattern on the target... The lightpipe has an entry surface through which the aiming beam enters the lightpipe, an exit surface through which the aiming beam exits the lightpipe, and a pair of total internal reflecting surfaces between the entry and exit surfaces for twice folding the aiming beam to pass through the lightpipe along a double-folded path
Data Source
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AI summary
A lightpipe, which is mounted on one chassis part of an imaging module of an imaging reader, optically modifies an aiming beam emitted by an aiming laser, which is mounted on another chassis part of the imaging module, to generate and shape an aiming light pattern on a target. In one embodiment, at least one, or both, of the chassis parts are movable relative to each other to spatially adjust the aiming light pattern relative to an imaging field of view. In another embodiment, the aiming laser and the lightpipe are received in respective pockets of the chassis parts with clearance, and are adjustably fixed in place to spatially adjust the aiming light pattern relative to the imaging field of view.