Switchable Polarizing Unit for Optical Code Readers
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Solution Overview
Problem
Conventional optical information readers face challenges in miniaturization due to the need for multiple illumination units with and without polarizing filters to effectively read information codes on both smooth and uneven surfaces, leading to increased size and complexity.
Innovation Solution
An optical information reader with a switching polarizing unit that can switch between polarized and unpolarized states, allowing the same illumination unit to adapt to different surface types by adjusting the polarization direction of the illumination and reflected light, eliminating the need for multiple illumination units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple illumination units with and without polarizing filters are prepared to read information codes on different surface types, then reading capability on both smooth and uneven surfaces is improved, but device size and complexity increase
Solution Approach 1:
The patent merges the functions of multiple illumination units (with and without polarizing filters) into a single illumination unit by placing both a polarizing filter and a non-polarizing filter in series on the light exit side. This allows the single unit to adapt to different surface types by controlling which filter is active, thereby reducing device complexity while maintaining versatility.
Solution Approach 2:
The patent introduces dynamic control by making the illumination unit's polarization state switchable. A switching element (such as a liquid crystal variable retarder or electro-optic modulator) is incorporated to dynamically change the polarization state of the illumination light based on the surface type being read, enabling adaptability without requiring multiple fixed illumination units.
2Object-affected harmful factors
If both polarizing filters are set to suppress specular reflection, then reading on smooth surfaces is improved, but contrast on uneven surfaces is lost
Solution Approach 1:
The patent changes the polarization parameter of the illumination light dynamically. By controlling the polarization state (e.g., switching between linear polarization at different angles or between polarized and unpolarized states), the system optimizes the balance between specular reflection suppression and contrast maintenance on uneven surfaces, resolving the contradiction between these two requirements.
3Illumination intensity
If illumination unit size is enlarged to secure sufficient illumination light when only one lighting unit is used, then illuminance is improved, but miniaturization of the optical system becomes difficult
Solution Approach 1:
The patent makes the single illumination unit universal by equipping it with multiple filtering capabilities (both polarizing and non-polarizing filters). This multi-functionality allows the unit to operate efficiently in different modes (suppressing specular reflection or maintaining contrast) without requiring multiple separate illumination units, thereby maintaining adequate illuminance while enabling miniaturization.
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 configuration enables efficient reading of information codes on both smooth and uneven surfaces while reducing the size and complexity of the optical system, ensuring adequate illumination and minimizing specular reflection effects.
Implementation Method 1
The first polarizing unit is configured so that the illumination light is polarized in a predetermined polarization direction
Implementation Method 2
the second polarizing unit is configured as a switching polarizing unit that can switch between a state in which the reflected light is polarized in a direction different from the predetermined polarization direction and a state in which the reflected light passes without being polarized
Implementation Method 3
since the light due to specular reflection retains the polarized light at the time of reflection
Data Source
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AI summary
A first polarizing unit (41) arranged on the light-exit side of a lighting unit (31) is configured to polarize illumination light therefrom in a predetermined polarization direction. In addition, a second polarizing unit (42) arranged on the light-reception side of a light receiving sensor (32) is configured as a switchable polarization unit, in which the switchable polarization unit is capable of performing a switchover between a polarized state in which light reflected from an information code (C) is polarized in a direction different from the predetermined polarization direction and a passing state where polarized reflected light passes therethrough without being polarized.