Perfector Camera Placement for Immediate Print Quality Detection
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Solution Overview
Problem
Conventional perfectors face delays in detecting defective paper sheets due to long transport distances, leading to increased waste and a larger machine size, and require additional parts and maintenance burdens for operators.
Innovation Solution
A perfector design with a first checking camera positioned on the discharging unit side of the transfer cylinder and a second checking camera on the feeding unit side of the delivery cylinder, allowing for immediate surface checks after printing without increasing the machine's size or part count, utilizing existing cylinder arrangements to reduce waste and operator burden.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the paper sheet is transported through multiple transfer cylinders and delivery chains to reach the checking position, then the checking can be performed after both surfaces are printed, but the transport distance becomes long causing delayed detection and increased waste sheets
Solution Approach 1:
The checking cameras are positioned to detect printing quality on the transfer cylinder and delivery cylinder immediately after printing, before the paper sheet completes its full transport path. This preliminary detection allows early identification of defective sheets, reducing waste accumulation on the delivery chain while maintaining reliable quality checking of both printed surfaces.
2Reliability
If dedicated transfer cylinders are added between the delivery chains to enable checking, then printing quality can be detected on both surfaces, but the number of parts increases causing larger perfector size and higher cost
Solution Approach 1:
The existing transfer cylinder and delivery cylinder, which serve the primary function of transporting paper sheets between printing units and delivery, are also utilized as checking positions for quality detection. By mounting checking cameras to detect prints on these existing cylinders, the system achieves dual-functionality: transport and quality checking, thereby avoiding the need for additional dedicated transfer cylinders and reducing overall device complexity.
3Loss of time
If the checking position is moved closer to the printing position to reduce transport distance, then detection speed improves, but the available space for camera installation becomes extremely limited
Solution Approach 1:
The checking cameras are positioned to detect printing quality on the cylindrical surfaces of the transfer and delivery cylinders, utilizing the circumferential space around these rotating components. This approach transforms the limited linear space near the printing position into adequate three-dimensional checking space by wrapping the detection path around the cylinder circumference, allowing sufficient camera installation while maintaining close proximity to the printing position for rapid detection.
Data Source
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AI summary
A perfector includes: a printing unit 1 configured to perform printing simultaneously on both surfaces of a paper sheet W; detecting means for detecting printing conditions on both surfaces of the paper sheet W; and transporting means for holding and transporting the paper sheet W to a delivery unit 16. The printing unit 1 includes: a blanket impression cylinder 2 configured to hold and transport the paper sheet W; and a blanket cylinder 3 being lateral to the blanket impression cylinder 2 and being in contact with the blanket impression cylinder 2. The transporting means includes: a transfer cylinder 13 being in contact with a lower side of the blanket impression cylinder 2 and configured to receive the paper sheet W from the blanket impression cylinder 2; and a delivery cylinder 17a being in contact with a lower side of the transfer cylinder 13 and configured to receive the paper sheet W from the transfer cylinder 13. The detecting means includes: a first checking camera 25 configured to detect the printing condition on one surface of the paper sheet W transported by the transfer cylinder 13; and a second checking camera 27 configured to detect the printing condition on the other surface of the paper sheet W transported by the delivery cylinder 17a.