1. Field of the Invention
The present invention relates to a maintenance apparatus for an inkjet-type print head.
2. Description of the Related Art
Generally speaking, inkjet printers print by discharging ink drops to a desired position from plural nozzles in a print head mounted on a bidirectionally travelling carriage.
Maintenance operations for appropriately cleaning the print head in a service area outside of the normal printing area include capping the print head with a cap that enables communication with air when the print head is not used for a long time, an ink vacuuming process for sucking ink that has increased in viscosity (referred to below as xe2x80x9cviscous inkxe2x80x9d) from inside the nozzles while the print head is sealed with the cap, and a wiping process using a wiper to wipe normal ink, viscous ink, and other contamination from the nozzle surface of the print head.
Devices performing such maintenance operations must be able to move the cap and wiper toward and away from the print head. A maintenance apparatus according to the related art is therefore typically configured to move the cap in conjunction with movement of the carriage, and to move the wiper along a specific path through a cam mechanism using, for example, the drive power of a pump used for vacuuming ink as the drive power source, or is configured to move the cap and the wiper along separate paths using a similar cam mechanism.
A problem with a maintenance apparatus according to the related art as noted above is that a longer carriage path must be provided in order for the cap to move in conjunction with carriage movement. This necessarily increases the size of the printer.
The cap must also be movable between three distinct positions: a retracted position where the cap is separated from the print head, a capping position where the cap covers the nozzle surface of the print head, and a sealed position where the nozzle surface is completely sealed for vacuuming ink from the nozzles. The cam mechanism required for the cap to move between these three positions independently of wiper movement is, however, complex and independent movement can be difficult to achieve.
More particularly, the space inside the cap must be able to communicate with the air while the cap covers the nozzle surface when in the capping position. A valve must therefore be provided in the cap, and a further problem is that the mechanism for opening and closing this valve is complex.
The present invention is directed to a solution to these problems, and an object of the invention is to provide a maintenance apparatus simplifying the cam mechanism for moving the cap and wiper and enabling the printer itself to therefore be made smaller.
To achieve these objects a maintenance apparatus for maintaining a print head having nozzles for discharging ink droplets and nozzle surface on which the nozzles are disposed, according to the present invention has a cap for covering the nozzles; a wiper for wiping the nozzle surface; and a cam member that is a rotatably disposed solid of revolution having on a side part thereof a first cam part for moving the cap and a second cam part for moving the wiper.
By linking movement of the cap and wiper using the first and second cam parts of the cam member, the present invention can cover or seal the print head with the cap without linking the capping mechanism to print head movement as in the related art. A printer comprising a maintenance apparatus according to the present invention can therefore be made smaller and the cam mechanism can be simplified because a single cam member is sufficient and a complicated cam mechanism is not required.
Further preferably, the maintenance apparatus also has a first slider movably supporting the cap and engaging the first cam part of the cam member to move the cap toward or away from the nozzle surface. A spring is also preferably positioned between the first slider and cap for urging the cap toward plane of the nozzle surface of the print head. The cap also preferably has a through-hole for communicating with air, and the first slider has a valve for opening and closing the through-hole. Yet further preferably, in this case, the first cam part of the cam member has a cam face for moving the cap between a sealed position whereat the valve is closed and the nozzles are covered, a covered position whereat the valve is open and the nozzles are covered, and a retracted position separated from the print head, in conjunction with cam member rotation.
Driving a pump communicating with the cap when the cap is in the sealed position can purge ink inside the nozzles of the print head. When the cap is in the covered position the cap communicates with the air through the through-hole. Driving the pump in the covered position without vacuuming ink from the nozzles can therefore purge ink inside the cap. The first slider when pressed against the print head movably supports the cap, and the sealed and covered positions of the cap can therefore be set within the range of first slider movement. The cap can therefore be moved between the sealed position and covered position by simply changing the position of the slider, that is, by rotating the cam member.
The through-hole is preferably formed in the back of the cap and the valve is formed on the first slider at a position opposing the through-hole. The through-hole separates from the valve and the valve opens due to action of the spring when the cap moves from the sealed position to the covered position. The cap can therefore be easily changed from the sealed position to the covered position without using a complex valve mechanism.
Yet further preferably, the cam face of the first cam part has areas where the cap remains in each of the sealed position, the covered position, and the retracted position as the cam member rotates through a respective specific angle. This makes it easier to control movement of the cap to each of these positions.
Yet further preferably, the first slider has a lock part for fixing the print head in its home position. By making this lock part an integral part of the first slider the print head can be fixed in conjunction with movement of the first slider. It is therefore not necessary to provide a separate member for fixing the print head position and a mechanism for moving this separate member, and the capping mechanism itself is therefore simplified.
Yet further preferably, the second cam part of the cam member has a cam face for moving the wiper in conjunction with rotation of the cam member between a retracted position separated from the print head and plural wiping positions at different distances from the retracted position. By thus using a mechanism for changing the wiper position the wiper can be moved between, for example, a first wiping position for cleaning the nozzles and a second wiping position for cleaning the wiper itself, thereby enabling more precise maintenance. The cam face of the second cam part further preferably has areas where the wiper remains in each of the first wiping position, the second wiping position, and the retracted position as the cam member rotates through a respective angle. This makes it easier to control the movement of the wiper to each of these positions.
The first and second cam parts of the cam member are preferably related such that the wiper is in the retracted position when the cap is in the sealed position or covered position, and the cap is in the retracted position when the wiper is in a wiping position. The cap thus does not move during the wiping process, and the wiping operation can therefore be run independently of the capping process and ink vacuuming process.
Furthermore, by making the maintenance apparatus smaller, the present invention also enables reducing the size of the printer, and the control components can also be simplified because the maintenance process can be accomplished by controlling primarily the angle of cam member rotation.
Other objects and attainments together with a fuller understanding of the invention will become apparent and appreciated by referring to the following description and claims taken in conjunction with the accompanying drawings.