Compact Imaging Lens Assembly for Barcode Readers
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Solution Overview
Problem
Existing imaging lens assemblies for solid-state imagers in barcode readers are large and bulky, limiting their use in portable and mobile applications where size and weight are a concern.
Innovation Solution
A compact imaging lens assembly is designed with a pair of end focusing lenses of the same size and optical power, an intermediate lens of opposite sign and compensating power, and an aperture stop, which reduces the overall size and weight while maintaining optical balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional imaging lens assembly is used to focus light onto the image sensor, then the optical function is satisfied, but the overall size and weight of the reader increases
Solution Approach 1:
The lens assembly is segmented into multiple lens elements with specific optical powers. By dividing the optical system into discrete elements (first lens with positive power, second lens with negative power, third lens with positive power), the patent achieves the required optical focusing function while distributing the optical load across smaller components, thereby reducing overall weight and size.
Solution Approach 2:
The patent employs parameter changes by assigning specific optical power relationships among the lens elements. The first and third lenses have positive optical powers, while the second lens has a negative optical power. This parameter configuration allows the system to maintain effective focusing capability while using smaller, lighter lens elements compared to a single large lens assembly.
2Reliability
If a conventional imaging lens assembly is used to focus light onto the image sensor, then the optical function is satisfied, but the overall volume of the reader increases
Solution Approach 1:
The lens assembly is divided into multiple compact lens elements arranged in sequence along the optical axis. This segmentation allows each element to be smaller in individual volume while collectively achieving the required optical path length and focusing function, thereby reducing the overall volume of the lens assembly.
Solution Approach 2:
The patent arranges the lens elements along the optical axis (one dimension) in a compact sequence, rather than spreading them out in a larger two-dimensional or three-dimensional configuration. This dimensional arrangement optimizes the volume efficiency of the lens assembly while maintaining the necessary optical path.
3Adaptability or versatility
If lens elements of different sizes and powers are used, then optical flexibility is improved, but the complexity of the lens assembly increases
Solution Approach 1:
Each lens element is assigned a specific local optical quality (positive or negative optical power) suited to its position in the optical sequence. The first and third lenses have positive optical powers for converging light, while the second lens has negative optical power for diverging light. This localized optimization of optical properties achieves the required overall optical flexibility without requiring excessive complexity in the overall assembly design.
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 compact lens assembly effectively focuses illumination light onto the imager, enabling efficient reading of one- or two-dimensional symbols in low light environments and is suitable for portable and mobile applications.
Implementation Method 1
an imaging lens assembly in front of the image sensor device... The lens assembly typically comprises a plurality of lenses of different sizes and powers... The imaging lens assembly effectively focuses illumination light onto the imager
Data Source
AI summary
A compact imaging lens assembly focuses light from indicia along an optical path onto a solid-state imager of an imaging reader. The lens assembly includes a pair of end focusing lenses of substantially a same size and spaced apart along the optical path, an intermediate lens between the end lenses, and an aperture stop between the end lenses.