Porous Vacuum Substrate for Envelope Printer Flatness
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Solution Overview
Problem
Printing machines face challenges in maintaining a consistent distance between printable substrates and inkjet print heads due to substrate thickness variations and the difficulty in flattening and securing substrates like envelopes, leading to potential damage and operational issues.
Innovation Solution
A transfer device with a platen and transport belt system that uses a porous vacuum substrate to limit negative pressure and exert a controlled force on the substrate, ensuring it remains flat and aligned with the print heads, while allowing air flow to prevent excessive friction and maintain image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If vacuum level is increased to flatten and smooth out the substrate, then substrate flatness is improved, but friction between the transport belt and the underlying surface increases leading to operational and maintenance problems
Solution Approach 1:
The patent employs a porous vacuum substrate that allows controlled air flow through its structure. The porosity enables the vacuum to act on the substrate for flattening while simultaneously allowing air to pass through and reduce friction between the transport belt and the underlying surface, thus resolving the contradiction between achieving flatness and minimizing friction
Solution Approach 2:
The patent changes the physical state and properties of the vacuum substrate by making it porous with specific flow characteristics. This parameter change allows the system to maintain different vacuum levels in different regions - high vacuum for substrate flattening where needed, and lower vacuum/air flow where friction reduction is prioritized
2Reliability
If vacuum hold down is used to secure the substrate, then substrate positioning is improved, but excessive negative pressure causes increased friction and operational issues
Solution Approach 1:
The porous vacuum substrate structure allows selective air flow that moderates the vacuum pressure. It secures the substrate through vacuum hold down while the porous nature allows excess air to pass through, preventing excessive negative pressure that would cause high friction and operational problems
3Reliability
If high vacuum force is applied to flatten multi-layer envelopes, then bottom layer holding is improved, but top layer smoothing is insufficient and print head engagement risk remains
Solution Approach 1:
The patent applies different vacuum characteristics to different regions and layers. The porous substrate allows air flow that differentially affects the top and bottom layers of multi-layer envelopes, providing sufficient holding force while enabling the top layer to be properly smoothed for print head engagement
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
The solution effectively flattens and secures printable substrates, preventing damage to print heads and reducing operational issues by maintaining a consistent distance and minimizing friction, thus enhancing image quality and operational efficiency.
Implementation Method 1
a porous vacuum substrate disposed between the hold down plate and the transport belt... applying a vacuum to the platen to secure the printable substrate to the transport belt
Implementation Method 2
The vacuum substrate permits air to be drawn into a space between the hold down plate and the transport belt
Data Source
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AI summary
A printable substrate transfer device (10) for a printing machine which includes a platen (28) that has openings therein in fluid communication with a vacuum source. A transport belt (32) is movable over the platen in a process direction. The transport belt allows air to pass there through. A hold down plate (38) is disposed above the transport belt. A stationary porous vacuum substrate (44) is disposed between the hold down plate and the transport belt. The vacuum substrate and transport belt form a path there between through which a printable substrate travels. The hold down plate exerts a force toward the transport belt upon operation of vacuum passing through the platen. The vacuum substrate limits the negative pressure between the hold down plate and the transport belt, such that a force exerted by the hold down plate onto the substrate is limited.