Light-Shielding Portion for Printing Apparatus Alignment Detection
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Solution Overview
Problem
Existing printing apparatuses face issues with erroneous detection of alignment patterns on the rear surface of a medium due to ambient light interference when printing on the front surface, leading to inaccurate alignment and reduced detection precision.
Innovation Solution
A printing apparatus is designed with a light-shielding portion that blocks ambient light from reaching the detecting unit, allowing for precise detection of the alignment pattern on the rear surface by reflecting light through the medium, and positioning the detecting unit upstream of the printing unit to ensure accurate alignment for both single-side and double-side printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the detecting unit receives reflected light from the rear surface of the medium to detect the alignment pattern, then the alignment detection function is achieved, but ambient light interferes with the detection causing erroneous results
Solution Approach 1:
A light-shielding portion is introduced as an intermediary element between the ambient light source and the detecting unit. This light-shielding portion selectively blocks ambient light from reaching the detecting unit while allowing the reflected light from the alignment pattern to pass through, thereby mediating the interaction between light sources and the detector to eliminate interference.
Solution Approach 2:
The light-shielding portion is designed with a segmented structure that includes a light-shielding region and a light-transmitting region. The light-shielding region blocks ambient light, while the light-transmitting region allows reflected light from the alignment pattern to reach the detecting unit. This segmentation enables selective light control to improve detection precision.
2Adaptability or versatility
If the detecting unit is positioned to face the rear surface of the medium for detection, then alignment pattern detection is enabled, but the structure becomes more complex
Solution Approach 1:
The light-shielding portion is integrated into the existing printing apparatus structure, serving multiple functions: it shields ambient light, transmits detection light, and maintains the structural integrity of the apparatus. This multi-functionality approach adds detection capability without proportionally increasing device complexity.
Solution Approach 2:
The light-shielding portion is merged with the support portion or housing structure of the printing apparatus, combining the light-shielding function with existing structural elements. This integration approach enables rear surface detection capability while minimizing additional structural complexity.
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 effectively suppresses erroneous detection caused by ambient light, enhances detection precision, and improves throughput by allowing seamless connection of printing between images on both surfaces of the medium.
Implementation Method 1
a light-shielding portion that faces the detecting unit with the medium interposed therebetween during at least transport of the medium by the transport unit
Implementation Method 2
a detecting unit that receives reflected light which is emitted on a rear surface of the medium
Implementation Method 3
the light-shielding portion has a reflecting portion that is able to reflect light, that is irradiated from the detecting unit, toward the detecting unit
Data Source
AI summary
A printing apparatus includes a transport unit that transports a medium in a transport direction, a support portion that supports the medium that is transported by the transport unit in a width direction that intersects with the transport direction, a printing unit that performs printing on a front surface of the medium which is supported by the support portion, a detecting unit that receives reflected light which is emitted on a rear surface of the medium that is transported on a detection position that is provided in a transport path of the medium, and a light-shielding portion that faces the detecting unit with the medium interposed therebetween during at least transport of the medium by the transport unit.