Single Wiper Printhead Maintenance via Low Pressure Assist
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Solution Overview
Problem
Existing inkjet printing systems require a separate wiper for each printhead to prevent damage during maintenance, leading to increased costs and inefficiency, as they need to perform purging operations to avoid friction issues without ink present on the printhead face.
Innovation Solution
A system where a single wiper can clean multiple printheads by applying a purge pressure to identified problematic printheads and a lower assist pressure to all printheads, forming a convex meniscus of ink to lubricate and allow simultaneous wiping without damaging inkjet ejectors, reducing the need for separate wipers and actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate wiper is used for each printhead, then each printhead can be wiped independently without damage, but the device complexity and maintenance cost increase
Solution Approach 1:
The patent segments the wiping function by applying different pressure levels to different printhead groups. Problematic printheads receive high purge pressure while non-problematic printheads receive low assist pressure, allowing a single wiper to safely service all printheads without requiring individual wipers for each printhead
Solution Approach 2:
The patent applies local quality by providing different pressure characteristics to different spatial zones (problematic vs. non-problematic printheads). This localized pressure differentiation ensures that ink is present at the aperture plate for non-problematic printheads during wiping, preventing damage while maintaining the ability to clear blocked jets in problematic printheads
2Reliability
If purging operation is performed on all printheads, then all inkjets can be cleared of blockages, but ink loss increases
Solution Approach 1:
The patent applies partial action by performing full purging operations only on printheads that are detected as problematic, while applying only low-pressure assist to non-problematic printheads. This selective approach clears blocked inkjets where needed while minimizing unnecessary ink loss from printheads that are already functioning properly
Solution Approach 2:
The system uses detection mechanisms to identify which printheads require maintenance, allowing the maintenance system to self-adjust its operation. Only printheads that need help receive the intensive purging treatment, while others receive minimal assist pressure to maintain ink presence during wiping without full purging
3Device complexity
If low pressure assist is applied to all printheads, then a single wiper can service all printheads without damage, but the friction during wiping increases for non-problematic printheads
Solution Approach 1:
The patent changes the pressure parameter from high (purge pressure) to low (assist pressure) for non-problematic printheads during the wiping operation. This parameter change ensures that enough ink remains at the aperture plate to provide lubrication and reduce friction during wiping, while still allowing a single wiper to service all printheads
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 approach enables effective maintenance of multiple printheads with a single wiper, reducing ink loss and maintenance costs while preventing damage to inkjet ejectors, allowing for efficient cleaning of all printheads without individual purging operations.
Implementation Method 1
a pressure source operatively connected to the ink reservoir to pressurize the ink in the ink reservoir to one of a first and second pressure
Implementation Method 2
forming a convex meniscus of ink at apertures of the inkjet ejectors
Implementation Method 3
The presence of the ink helps reduce the friction caused by wiping the face plate
Data Source
AI summary
A method of performing maintenance on printheads of an imaging device includes the detection of at least one missing or defective inkjet in a printhead. A first pressure is applied to ink in printheads in which at least one missing or defective inkjet was detected. The first pressure is configured to discharge ink from the plurality of apertures in an aperture plate of the printhead to reestablish fluid continuity through the inkjet. A second pressure is applied to all of the printheads to be wiped. The second pressure is configured to form a convex meniscus at the plurality of apertures in the aperture plate of all of the printheads to be wiped. A single actuator is then operated to move one or more wipers into engagement with the printheads to be wiped. During wiping the convex meniscus is encountered by a wiper to lubricate a printhead and prevent the printhead from being damaged by wiping. The single actuator then retracts the one or more wipers from the printheads.