Sheet feeding or delivering – Feeding – Pack holders
Reexamination Certificate
1999-03-26
2001-02-06
Skaggs, H. Grant (Department: 3651)
Sheet feeding or delivering
Feeding
Pack holders
C271S127000, C271S171000
Reexamination Certificate
active
06182963
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to media trays for sheet material feed systems in imaging devices. Specifically, the present invention relates to automated force balance adjustment mechanisms to accommodate broad ranges of media for sheet material cassette trays.
BACKGROUND OF THE INVENTION
The ever-changing demands of global commerce, coupled with the almost unlimited capabilities of state-of-the-art imaging systems, has resulted in a need for a wide variety of document types and formats. The days of “letter or legal” have gone the way of carbon paper and mimeographs. Imaging systems are capable of handling a variety of standard sizes, such as letter, legal, A4, and A5-ISO, as well as custom sheet sizes.
Rather than require system users to have on hand a different sheet tray for each sheet size, it is known to provide cassette trays having the ability to handle a relatively wide range of sizes. Such trays typically are provided with sliding rear adjusts to accommodate different sheet lengths, and/or sliding side adjusts to accommodate different sheet widths. A spring-biased lift plate is typically provided to urge the sheet stack towards an infeed mechanism, such as feed rollers and the like.
It has been found that the difference in weight between smaller and larger sheet sizes can present problems. For example, if the spring bias of the lift plate is chosen for an “average” sheet size, heavier sheet stacks can have “no-pick” problems, where the spring bias is insufficient to overcome the weight of the stacks while still providing the necessary pick force. At the other end of the spectrum, smaller sheets may have “multi-feed” problems, wherein the pick force exceeds the separation force so that two or more sheets are fed into the feed mechanism simultaneously.
One proposed solution to these problems is to provide manual spring adjustments, where system users are required to adjust various levers and knobs corresponding to individual sheet sizes.
Unfortunately, this solution presents problems of its own. For instance it is difficult or impossible for users to adjust for non-standard sizes. Further, the requirement for independent manual adjustment by the user is inconvenient, and may be easily overlooked.
It is therefore apparent that the need exists for a sheet material tray having a simple, reliable mechanism that will automatically adjust spring bias to paper size without any additional mechanical manipulation by the system user.
SUMMARY OF THE INVENTION
These and other objects are achieved by providing, in a sheet material feed assembly, a sheet material tray including a movable support component. Also provided is a spring adapted to bias the support component in a predetermined direction. A selectively movable sheet retention member is operatively connected to the spring, whereby movement of the sheet retention member automatically affects variation in the biasing force of the spring.
The spring can be provided as a pivotable cantilever spring including a central aperture. The sheet retention member can include a ramp member passing through the cantilever spring aperture. The ramp member includes an inclined portion, and a flat portion contiguous with the inclined portion.
The sheet retention member can be provided in the form of a rear adjust for accommodating various sheet material lengths within the tray. The movable support component can be mounted for pivoting movement within the tray, and can be provided as a sheet material lift plate. A second spring member can be provided in biasing contact with the lift plate.
A method for automatically adjusting tray force balance forces is also set forth. The method is adapted for practice with a paper tray associated with an imaging system including a sheet material feed assembly.
In a first step, a selectively movable sheet retention member is provided. Next, a bias spring, adapted and constructed to exert a selectively variable biasing force on sheet material in the paper tray, is provided. A spring adjustment mechanism is operatively connected to the sheet retention member and to the bias spring. The sheet retention member is then moved to cause the spring adjustment mechanism to selectively vary the biasing force of the bias spring. The sheet retention member can be moved forward to decrease the biasing force of the bias spring, and rearward to increase the biasing force of the bias spring.
REFERENCES:
patent: 4343461 (1982-08-01), Tomimoti et al.
patent: 4726698 (1988-02-01), Weiss et al.
patent: 6039315 (2000-03-01), Lim
patent: 0084735 (1980-06-01), None
patent: 0082744 (1981-07-01), None
patent: 0291324 (1990-12-01), None
patent: 404313523 (1992-11-01), None
patent: 405069955 (1993-03-01), None
patent: 406016254 (1994-01-01), None
Hewlett-Packard Co.
Skaggs H. Grant
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