Electrostatic Belt Transport for Multi-Head Printer Registration
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Solution Overview
Problem
Existing sheet transport systems in multi-print head printers face challenges such as image distortion, paper jams, and ink smudging due to air currents and inadequate suction, especially at high processing speeds, which are exacerbated by the need for precise registration and close spacing of print heads.
Innovation Solution
A printer system utilizing a continuous belt made of a highly dielectric material like Mylar, with a charging mechanism to electrostatically tack the sheet medium, a positioning subsystem for precise image alignment, and control modules to coordinate print head operations, ensuring accurate registration and minimizing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a vacuum belt system is used to transport sheets, then sheet transport is achieved, but air currents in the vacuum plenum disturb ink paths causing image distortion
Solution Approach 1:
The patent removes the sheet from the vacuum belt transport system before the printing zone. Sheets are fed onto the belt, but then transferred to a non-contact transport mechanism (such as a air cushion or magnetic field) that does not rely on vacuum suction, thereby eliminating the air current problem in the plenum while maintaining sheet transport reliability
Solution Approach 2:
The patent introduces an intermediary transport mechanism between the vacuum belt and the print head. This intermediary system (such as a air bearing or magnetic transport layer) carries the sheet through the printing zone without requiring vacuum suction, thus preventing air current interference with ink droplet paths while maintaining continuous sheet transport
2Productivity
If print heads are spaced closely in transport direction, then high processing speed is achieved, but sheet movement between print heads degrades combined image quality
Solution Approach 1:
The patent replaces mechanical contact-based sheet holding (vacuum suction or roller nips) with a non-contact transport mechanism. This substitution allows print heads to be positioned very close together for high-speed processing while the non-contact mechanism prevents sheet movement or skewing that would occur with mechanical holding, thereby maintaining precise image registration across multiple print heads
3Reliability
If vacuum suction is applied to hold sheet against belt, then sheet transport is maintained, but suction is reduced at idler rollers causing sheet lifting or curling
Solution Approach 1:
The patent extracts the vacuum suction mechanism from the printing zone and replaces it with a non-contact transport system. This eliminates the problem of reduced suction at idler rollers causing sheet lifting or curling, while maintaining continuous sheet transport through the printing zone without requiring vacuum pressure
Solution Approach 2:
The patent introduces an intermediary non-contact transport mechanism (such as air cushion or magnetic field) that maintains sheet contact with the belt throughout the printing zone without requiring vacuum suction. This intermediary system prevents sheet lifting or curling at idler rollers while maintaining stable sheet position for precise printing
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 solution enables precise and efficient transportation of sheet media across multiple print heads, maintaining image quality and preventing paper jams, even at high speeds, by ensuring accurate registration and reducing contamination risks.
Implementation Method 1
a charging means to charge the sheet medium to electrostatically tack the sheet medium to the belt
Data Source
AI summary
A printing apparatus has a series of inkjet print heads spaced from one another in a transport direction. A continuous belt driven around a roller system is used to feed sheet media successively to the print heads so that a partial image printed by one print head is overprinted at a subsequent print head with registration of the partial images. A sheet medium is caused to become electrostatically tacked to the belt by passing the sheet past a charging device. Movement of the belt is tracked by a tracking sub-system and operation of the print heads is coordinated with the tracked belt movement to achieve precise registration of the partial images.