Variable Focus Imaging Reader for Hands-Free Barcode Scanning
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Solution Overview
Problem
Conventional auto-focus camera systems in barcode scanners face operational delays and increased complexity and cost due to shallow depth of focus and slow focusing times, particularly in hands-free operation modes with varying working distances.
Innovation Solution
A variable focus imaging reader with a controller that determines and captures images at discrete imaging planes within a working distance, bypassing autofocus functionality to enable faster and more efficient barcode scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If auto-focus camera systems are used to capture images at different distances, then the system can adapt to varying working distances, but the focusing time increases and operational speed decreases
Solution Approach 1:
The continuous focusing range is segmented into multiple discrete imaging planes. Instead of continuously adjusting focus for every distance, the system divides the working distance into specific planes (e.g., near, mid, far) and only focuses on these predetermined planes, significantly reducing focusing time while maintaining adaptability to varying distances.
Solution Approach 2:
The imaging planes are predetermined and pre-configured before scanning begins. The system prepares the focus settings for these specific planes in advance, so when an object is detected, the system can immediately switch to the appropriate pre-configured plane without performing continuous autofocus adjustments.
2Adaptability or versatility
If auto-focus camera systems with large lens apertures are used, then the system can focus on objects at different distances, but the depth of focus becomes shallower requiring more precise focusing
Solution Approach 1:
By segmenting the focusing range into discrete planes, the system compensates for the shallow depth of focus. Each discrete plane is positioned to ensure adequate focus coverage, and the system jumps between these planes rather than attempting continuous focus, effectively managing the shallow depth of focus constraint.
3Reliability
If continuous autofocus functionality is implemented, then the system can maintain focus on moving objects, but the processing complexity and mechanical componentry increase
Solution Approach 1:
The system extracts and eliminates the continuous autofocus functionality from the imaging system. Instead of implementing full autofocus with its complex processors and mechanical components, the system retains only the essential focusing capability needed for discrete planes, removing unnecessary complexity while maintaining sufficient focus accuracy for barcode scanning applications.
Solution Approach 2:
The system uses simpler, less expensive focusing mechanisms that are sufficient for discrete plane imaging. Rather than investing in expensive, complex continuous autofocus systems with precision mechanical components, the patent employs simpler focusing solutions that are adequate for the specific application of scanning predetermined planes.
Data Source
AI summary
An imaging reader includes a light source generating an illumination beam over a working distance, and a variable focus imaging assembly with an image sensor, a variable focus optical element, a variable focus imaging controller that controls operation of the variable focus optical element to define a plurality of imaging planes over the working distance. The variable focus imaging controller assesses a variety of scanning parameters and determines the number of imaging planes over the working distance and the distance of each of imaging plane from the image sensor, to allow the imaging reader to capture images of a target object only at each of the imaging planes, thereby avoiding time-consuming autofocusing on the target. The imaging reader captures images in a sequential order greatly reducing image capture and image analysis processing time.