Sheet feeding or delivering – Delivering – By pneumatic conveyor
Reexamination Certificate
1999-10-28
2001-05-22
Bollinger, David H. (Department: 3651)
Sheet feeding or delivering
Delivering
By pneumatic conveyor
C347S104000, C347S164000, C347S197000, C347S215000, C347S264000, C346S136000
Reexamination Certificate
active
06234472
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to hardcopy apparatus, such as copiers, printers, scanners, facsimiles, and more particularly to improved media holddown devices for such apparatus.
BACKGROUND OF THE INVENTION
In hardcopy apparatus and particularly in apparatus handling media of big size, such as large format printers, printed media is outputted towards the outside of the printer by means of outputting means which may damage the quality of the printout. Conventional outputting means, in order to advance the printed media, employ elements for holding the media having a direct contact with the printed surface, which may cause ink smearing and other adverse affects on print appearance.
For instance, starwheels are employed in a number of apparatus for outputting printed media and may damage the printout with starwheel marks. Another drawback is the need to employ a mechanism or a structure to hold the starwheels themselves.
Conventionally, sheet holddown devices such as electrostatic or suction devices are employed only to reduce the effects of paper curl and cockle on dot placement during printing. In vacuum holddown devices, sheet flatness is maintained by providing suction between a support plate and the back surface of a sheet to be handled.
Cockle effect is the reluctance of the paper to bend smoothly. Instead it bends locally in a sharp fashion, creating permanent wrinkles.
Although conventional vacuum holddown devices are fairly effective in maintaining sheet flatness during printing, they have drawbacks. One drawback is the complexity of maintaining the same holddown force along the entire width of the medium while printing, i.e. in the direction of the printheads motion. This is due to the losses of air that the conventional devices allow, causing the medium to be subject to different forces, i.e. forcing the medium to rotate while it is advanced in the direction of the media motion.
Another drawback is that on one hand the maximum holddown force on a sheet is limited because of the necessity to maintain low frictional loads on transport devices which index the sheets. In conventional inkjet printers, such limitations can cause pen-to-sheet spacing distances to vary from swath to swath. Consequently, the holddown pressure at a localised area being printed may be insufficient to flatten cockles and other paper irregularities. On the other hand the vacuum required to eliminate cockle wrinkles in a printout would be so high that is normally unfeasible; in fact, high vacuum may suck the ink right through the paper and at the same time generate a lot of noise.
Applicant has then experimented that the employment of a vacuum holddown output unit may help media to be outputted without damaging the print appearance.
SUMMARY OF THE INVENTION
The present invention seeks to provide an improved hardcopy apparatus and method of outputted a printed medium in the hardcopy apparatus.
According to an aspect of the present invention, there is provided a hardcopy apparatus which comprises a main roller and an outputting mechanism for moving a medium outside of the hardcopy apparatus, said outputting mechanism comprises a vacuum holddown output unit for holding at least a portion of media down onto a surface of the outputting mechanism.
In this way the media is not held by any elements having a direct contact with the printed surface, which may cause ink smearing and other adverse affects on print appearance.
Preferably, said holddown unit comprises a vacuum source, connected to atmosphere through a plurality of first apertures formed into the surface, and a vacuum channel to generate a negative pressure capable of holding down at least a portion of media onto the surface.
In a preferred embodiment, said holddown unit further comprises advancing means capable, in co-operation with the generated negative pressure, to engage the back side of a medium and transfer said medium out of the hardcopy apparatus, and said advancing means comprise one or more wheels.
This avoids the use of starwheels in the apparatus, thus solving the problems of damaging the printout with starwheel marks and of employing a mechanism or a structure to hold the starwheels themselves.
In a preferred arrangement, said one or more wheels are rotating clockwise or counter-clockwise in order to output the medium from the apparatus.
Advantageously, the apparatus further comprises holding means for holding still a printed media for a predetermined dry time, and collecting means for collecting the printed media when released by the holding means, after the dry time, if any.
Viewing another aspect of the present invention, there is also provided method of outputting a printed medium from a hardcopy apparatus including a vacuum source, a main driving roller and a secondary roller, comprising the steps of: advancing the medium up to contact said secondary roller; generating a negative pressure, by means of the vacuum source, capable of engaging the back of the medium with the surface of the secondary roller; by rotating the main roller and the secondary roller, disengaging the medium from the main roller; and by rotating the secondary roller, advancing the medium towards the outside of the apparatus.
Preferably, the step of disengaging the medium from the main roller, comprises the step of cutting the medium.
In a preferred embodiment, the method further comprises the step of, stopping the rotation of the secondary roller (455) for a predetermined dry time. Typically, the method comprises the step of switching off the vacuum source, in order to collect the printout into collecting means.
Those operations are achieved in a particularly simple environment, where the same elements are operated in a different way in order to perform different scopes.
REFERENCES:
patent: 4285507 (1981-08-01), Marinoff
patent: 4646109 (1987-02-01), Toyama et al.
patent: 4998715 (1991-03-01), Milan et al.
patent: 5124728 (1992-06-01), Denda
patent: 5717446 (1998-02-01), Teumer et al.
patent: 0 379 306 A2 (1990-07-01), None
patent: 0 379 306 A3 (1990-07-01), None
Bollinger David H.
Hewlett--Packard Company
LandOfFree
Hardcopy apparatus and method for outputting media does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hardcopy apparatus and method for outputting media, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hardcopy apparatus and method for outputting media will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2516215