Large Format Printers usually consists on a Media Path (Y axis) which advances and rewinds the
media and a Scan Axis (X axis) which allows the Print Head Carriage to spit the ink while moving
perpendicular to the advancing direction of the media.
Print Head Carriage is a big and heavy component that contains all the needed Print Heads, Ink
management assets, Electronics, Sensors, etc.
Print Head Carriage is always in the capping station while it is not printing or doing any Service
routine as Print Heads needs to be in a capped mode to prevent them from becoming dry or getting
Capping Station is a passive element that engages and moves together with the Print Head Carriage
when this moves to the Capping Position, thereby capping and protecting the Print Heads to keep
them functional. Capping station is a slave tray equipped with as many caps as printheads on the
carriage. It is moved from rest (low) position to cap (high) position when the carriage is moved from
printing to "cap position" (-X direction). In order to ensure a proper alignment, it is spring loaded to
opposite direction (+X direction).
The lifting movement is currently done by X-Z axis guides with low-degree ramps in which the
capping tray is pulled along a -X direction and upwards by the carriage. Also, the spring generates a
force in the +X direction that may become critical for the Carriage's cap position since it can overcome
friction, move it along such +X direction and destabilize the servo control which could cause the
printheads to stay uncap and dry or generate unwanted continuous servo corrections and
movements to hold carriage on position.
Close to the Capping Station, there is a bump with two main functions:
(1) give the ZERO reference for the Print Head Carriage and (2) as a SAFETY element, avoid the Print
Head Carriage to come out from the Scan Axis if any malfunction occurs while printing.
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INC, HP, "PASSIVE CAPPING HOLD POSITION FOR PRINT HEAD CARRIAGE", Technical Disclosure Commons, (April 02, 2019)