Imaging Bar Code Reader Virtual Scan Line Decoding
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Solution Overview
Problem
Existing imaging-based bar code readers face challenges in decoding high density bar codes without increasing the number of pixels, which is costly and limits their ability to read narrow bar code elements effectively.
Innovation Solution
The system uses a 1D or 2D imaging array moved at an acute angle to generate a tilted image of the bar code, creating virtual scan lines where gray scale values are projected orthogonally, effectively increasing the pixels per module (PPM) and allowing for enhanced decoding capabilities without the need for additional pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of pixels is increased to improve decoding capability for high density bar codes, then the ability to read high density bar codes is improved, but the imaging system cost increases
Solution Approach 1:
The patent transforms the imaging approach from a single 2D image capture to a multi-dimensional process by capturing multiple images at different tilt angles and combining them through virtual scan lines. This dimensional transformation allows the system to achieve high decoding capability without increasing the physical pixel count, as the virtual scan lines create an effective multi-pixel sampling across the bar code elements.
Solution Approach 2:
The patent creates virtual copies of the bar code image at different tilt angles and positions. By generating multiple tilted images and projecting them onto virtual scan lines, the system creates replicated information that can be processed to enhance decoding capability. This virtual copying allows the system to effectively increase the number of sampling points without adding physical pixels.
2Device complexity
If the imaging system uses a 1D array to reduce cost, then the device complexity is reduced, but the ability to decode high density bar codes with narrow elements is limited
Solution Approach 1:
The patent introduces dynamic tilting of the imaging array relative to the bar code. Instead of a static 1D array capturing a single image, the system dynamically adjusts the array orientation at different angles during the imaging process. This dynamic approach allows the 1D array to effectively sample multiple positions along the bar code, achieving high pixels per module capability through motion rather than through a static 2D array.
Solution Approach 2:
The patent employs periodic tilting of the imaging array at specific angles during the imaging sequence. By repeating the imaging process at multiple discrete tilt angles and combining the results through virtual scan lines, the system creates a periodic sampling pattern that effectively increases the resolution and pixels per module capability of the 1D array configuration.
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 improves the ability to decode high density bar codes by increasing the effective PPM, enabling successful decoding at lower pixel densities, thus enhancing the system's capability to read high density bar codes without the cost and complexity of increasing pixel count.
Implementation Method 1
Light reflected from a target image, e.g., a target bar code is focused through a lens of the imaging system onto the pixel array
Implementation Method 2
Imaging systems include CCD arrays, CMOS arrays, or other imaging pixel arrays having a plurality of photosensitive elements or pixels
Data Source
AI summary
An imaging and decoding system for an imaging-based bar code reader. The imaging and decoding system includes an imaging system and a decoding system. The imaging system includes an imaging pixel array and a memory which function to: image the target bar code by scanning the target bar code at an acute angle with respect to a vertical axis of the target bar code to generate a tilted imaged bar code stored in memory, the tilted imaged bar code comprising an array of gray scale values stored in the memory; generate a virtual scan line traversing a horizontal width of the tilted imaged bar code; establish a zone about the virtual scan line; and project gray values within the zone onto the virtual scan line thereby generating a sequence of gray scale values associated with the virtual scan line, the sequence of gray scale values representative of a pattern of elements of the target bar code. The decoding system decodes the target bar code utilizing the sequence of values associated with the virtual scan line.