Position Detection Device Using Invisible Light Absorption
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Solution Overview
Problem
Existing position detection technologies face challenges in accurately reading the end positions and image formation positions of recording media, especially when the density difference between the media and the background or reference marks is small, leading to reduced productivity and increased complexity due to the need for background color switching and stabilization times.
Innovation Solution
A position detection device comprising a background member with high absorption characteristics in the invisible wavelength region, a reader capable of outputting visible and invisible images, and a control unit that selects the appropriate image for detection based on the absorption characteristics of the recording medium and mark materials, allowing for accurate position detection without switching the background color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the background portion color is switched to increase contrast with the conveyed object, then the reading accuracy of the outer edge position and processing position is improved, but the operation time for switching and waiting for stabilization increases, reducing productivity
Solution Approach 1:
The invention changes the wavelength parameter of light from visible to invisible (near-infrared) region to achieve high contrast between the conveyed object and background without physically switching the background color. This allows continuous operation without stopping for background switching and stabilization, thereby maintaining productivity while achieving accurate position detection.
Solution Approach 2:
The invention replaces the mechanical system of physically switching background portions with an optical system that uses invisible light irradiation. Instead of mechanically changing the background color, the system uses near-infrared light to create contrast, eliminating the need for mechanical switching operations and associated downtime.
2Measurement precision
If the background portion color is switched to increase contrast, then the reading accuracy is improved, but the apparatus configuration becomes more complicated
Solution Approach 1:
The invention replaces the complex mechanical switching mechanism for background portions with a simple optical illumination system using invisible light sources. This substitution eliminates the need for movable parts, switching mechanisms, and stabilization systems, thereby simplifying the overall apparatus configuration while maintaining high measurement precision.
Solution Approach 2:
The invention introduces an intermediary invisible light source (near-infrared illumination) between the light source and the detection system. This intermediary enables contrast enhancement without requiring physical modification of the background portions, thereby avoiding the complexity of background switching mechanisms while achieving accurate reference mark detection.
3Ease of operation
If visible light is used for reading, then the reading process is simple, but the density difference between the conveyed object and background must be large to achieve accurate detection
Solution Approach 1:
The invention changes the wavelength parameter of illumination light from visible to invisible (near-infrared) region. This parameter change enables the detection system to exploit differences in infrared absorption characteristics between the conveyed object and background, achieving high measurement precision even when visible density differences are small, while maintaining operational simplicity.
Solution Approach 2:
The invention uses periodic alternation between visible and invisible light irradiation to adapt to different detection needs. The system can switch between visible light for simple cases and invisible light for cases requiring high precision with small density differences, providing a flexible and simple reading process that maintains accuracy across various conditions.
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
Enables high-accuracy detection of end positions and image formation positions on various recording media with a simple configuration, reducing downtime and apparatus complexity while maintaining productivity.
Implementation Method 1
The background member has a higher absorption characteristic in an invisible wavelength region than in a visible wavelength region
Data Source
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AI summary
A position detection device (4) includes a background member (500), a reader (400), a position detection unit (41), and a control unit (42). The background member (500) has a higher absorption characteristic in an invisible wavelength region than in a visible wavelength region. The reader (400) opposite the background member irradiates a recording medium having a mark and the background member with light of a visible wavelength or an invisible wavelength to output a visible image or an invisible image. The position detection unit (41) detects an end position of the medium and a position of the mark on the medium from a read image output from the reader. The control unit (42) selects the visible or invisible image as the read image for position detection, according to an absorption characteristic of a color material forming the mark and an absorption characteristic of the medium in the invisible wavelength region.