Adaptive Illumination Bar Code Reader
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Solution Overview
Problem
Conventional bar code readers using white/red LEDs produce annoyingly bright illumination, while infrared LEDs are invisible and cannot detect symbols printed with thermal ink, leading to operator discomfort and reading challenges.
Innovation Solution
A bar code reader employing a combination of non-readily visible infrared LEDs and visible blue LEDs, where the infrared LED is continuously energized for low-density/high-contrast symbols and the blue LED is energized briefly for high-density/low-contrast symbols, to balance illumination comfort and reading capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If white/red LEDs are used for illumination, then reading capability is improved, but operator comfort deteriorates due to annoyingly bright illumination
Solution Approach 1:
The illumination function is segmented into multiple wavelength components (red LED at 630-675nm and infrared LED at 780-850nm) that can be independently controlled. This allows the system to provide only the necessary illumination wavelengths for reading symbols while filtering out the visible bright light that causes operator discomfort.
Solution Approach 2:
The patent applies different illumination qualities to different reading scenarios: visible red light provides adequate illumination for low-density symbols, while infrared light handles high-density symbols. This local quality differentiation optimizes both reading capability and operator comfort by matching illumination type to symbol characteristics.
2Object-affected harmful factors
If infrared LEDs are used for illumination, then operator comfort is improved, but reading capability deteriorates for symbols printed with thermal ink
Solution Approach 1:
The system dynamically switches between red LED and infrared LED illumination based on real-time detection of symbol density and contrast characteristics. The controller adjusts which LED is activated according to the specific reading task, optimizing both operator comfort and reading capability for different symbol types.
Solution Approach 2:
The patent changes the wavelength parameter of the illumination source based on the reading requirements. By switching between red light (630-675nm) and infrared light (780-850nm), the system adapts to different symbol characteristics while maintaining operator comfort and reading accuracy.
3Adaptability or versatility
If multiple LEDs are used simultaneously, then reading capability for various symbol types is improved, but device complexity increases
Solution Approach 1:
The system uses feedback from initial symbol detection to control which LED should be activated. The controller analyzes symbol characteristics (density, contrast) and automatically selects the appropriate illumination source, eliminating the need for manual configuration and reducing operational complexity.
Solution Approach 2:
The patent employs periodic switching between different LED illumination modes based on detected symbol characteristics. The system alternates between red LED and infrared LED activation in response to varying symbol types, providing versatile reading capability through rhythmic, automated control rather than continuous complex management.
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 reduces operator discomfort and enhances reading performance by maintaining sufficient illumination for low-density symbols while improving resolution and reading ability for high-density/low-contrast symbols.
Implementation Method 1
The illumination light is provided by at least one light emitting diode (LED), and preferably a plurality of LEDs
Implementation Method 2
Each LED emits the illumination light with a white, or preferably a red, color, typically in the visible light spectrum having a wavelength between about 620 nm and 675 nm
Implementation Method 3
The imager further includes at least one imaging lens to focus light returning from the symbol onto the photosensors
Implementation Method 4
The solid-state imager typically has a one- or two-dimensional array of cells or photosensors, also commonly referred to as pixels, which correspond to image elements or pixels in a field of view of the imager
Data Source
AI summary
Infrared light having a wavelength in a range from about 700 nm to about 760 nm, which is non-readily visible, illuminates indicia to be electro-optically read by default. Blue visible light having a wavelength in a range from about 430 nm to about 505 nm illuminates the indicia when high-density and/or low-contrast indicia are detected.