Printhead assembly capping device
View Patent ↗A capping device ( 12 ) for a printhead assembly ( 10 ) of a pagewidth drop on demand inkjet printer is formed of spring steel and includes an elastomeric onsert ( 47 ) having a series of recesses ( 56 ) which create chambers positioned over air inlet and exhaust holes ( 30 ) of each printhead module ( 11 ) of the assembly. These allow the air to flow from one inlet to the next outlet. When the capping device is moved to its capped position, the airways ( 32 ) are sealed off so as to prevent air from drying out and therefore blocking the delicate nozzles ( 62 ) of the printheads. Another function of the molding is to cover and clamp against nozzle guards ( 24 ) of the assembly to protect against drying out and also to keep foreign particles such as paper dust from entering and damaging the printer nozzles ( 62 ).
1. A printhead assembly for a drop on demand ink jet printer, comprising:
a printhead module having a printhead including ink jet nozzles, the module being affixed to the assembly,
a capping device affixed to the assembly and movable linearly with respect thereto, the capping device at least partially surrounding the printhead module and movable between a capped position whereby the nozzles are capped by the capping device and an uncapped position whereby the nozzles are uncapped.
2. The printhead assembly of claim 1 comprising a plurality of said printhead modules situated along a channel, the modules and channel extending substantially across a pagewidth.
3. The printhead assembly of claim 2 wherein the capping device partly surrounds the channel.
4. The printhead assembly of claim 3 wherein the capping device applies a compressive force to each printhead module and an underside of the channel.
5. The printhead assembly of claim 2 wherein the capping device has an onsert molded elastomeric pad which bears onto one or more of the printhead modules.
6. The printhead assembly of claim 5 wherein each printhead module includes a nozzle guard to protect the nozzles and wherein the elastomeric pad clamps against the nozzle guard in the capped position.
7. The printhead assembly of claim 6 wherein the elastomeric pad includes air ducts via which air is pumped to the printhead modules when the capping device is in the uncapped position.
8. The printhead assembly of claim 7 wherein each printhead module includes a ramp and wherein the capping device includes a boss that rides over the ramp when the capping device is moved between the capped and uncapped positions, the ramp serving to elastically distort the capping device as it is moved between said capped and uncapped positions so as to prevent scraping of the device against the nozzle guard.
9. The printhead assembly of claim 7 wherein each printhead module has alternating air inlets and outlets cooperating with the elastomeric pad so as to be either sealed off or grouped into air inlet/outlet chambers depending on the position of the capping device, the chambers serving to duct air to the printhead when the capping device is uncapped.
10. The printhead assembly of claim 2 further comprising a camshaft that bears against the capping device and serves to move the capping device between said capped and uncapped positions.
11. The printhead assembly of claim 10 wherein the capping device includes a spring to bias the device with respect to the printhead modules against the camshaft.
12. The printhead assembly of claim 10 wherein rotation of the camshaft is reversible.
13. The printhead assembly of claim 1 wherein the capping device is formed of stainless spring steel.