Sliding Cap Assembly with Rigid Mating Surface for Ink Jet Print Heads
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Solution Overview
Problem
Thermal ink jet printers face nozzle clogging due to ink drying when the print head is not in use, and existing capping devices require additional components and movement of the print head for maintenance, leading to slower capping and decapping processes.
Innovation Solution
A capping device with a sliding cap assembly and a rigid mating surface that directly engages the print head nozzles, allowing for automatic capping and decapping without moving the print head, thereby preventing ink evaporation and minimizing clogging, and enabling fast operation during production line stops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-contact molded or machined pocket is used to seal the nozzle area, then the nozzle clogging is prevented by maintaining fluid saturation, but any deviation from planarity between the cap and the pocket allows air into the pocket causing drying and loss of print capability
Solution Approach 1:
The patent uses a flexible membrane or thin film as the sealing surface between the cap and the pocket. This flexible element can conform to slight variations in planarity while maintaining an effective seal, preventing air from entering the pocket and causing drying. The flexibility allows the sealing surface to adapt to manufacturing tolerances without compromising the seal integrity.
2Reliability
If the print head is moved to a maintenance station for capping, then the nozzles are sealed when not printing, but additional components are required and the capping process slows down
Solution Approach 1:
The patent combines the capping function with the existing print head structure by integrating the cap assembly directly onto the print head carriage. This merging eliminates the need for a separate maintenance station and the associated complex mechanisms for moving the print head to and from maintenance positions. The cap can be applied and removed quickly at the printing position, maintaining nozzle sealing while improving productivity.
3Reliability
If the print head is moved to a maintenance station, then capping is achieved, but additional components and movement requirements increase device complexity and slow down the process
Solution Approach 1:
The patent extracts the capping function from the complex maintenance station system and integrates it directly into the print head carriage. This extraction eliminates the need for additional components such as separate maintenance station mechanisms, transfer arms, and complex positioning systems. The simplified design achieves the same nozzle sealing reliability with fewer moving parts and reduced device complexity.
Data Source
AI summary
A capping device for an ink jet print head includes a base configured to receive an ink jet print head and a cap assembly attached to the base. The cap assembly is configured for sliding movement with respect to the base to provide a closed position of the cap assembly when the print head is not printing and an open position to allow for the ejection of ink from nozzles when the print head is printing. The cap assembly includes a cover support and a cover attached to the cover support in a generally planar relationship thereto. The cover is adapted to provide additional movement with respect to the cover support in a direction different from the sliding direction. The cover includes a rigid mating surface configured to engage a surface of the print head adjacent the nozzles.