Sheet feeding or delivering – Feeding – Separators
Reexamination Certificate
2000-06-01
2001-11-20
Ellis, Christopher P. (Department: 3651)
Sheet feeding or delivering
Feeding
Separators
C271S021000, C271S121000
Reexamination Certificate
active
06318715
ABSTRACT:
The invention relates to a device for isolating sheets of a recording medium according to the preamble of claim
1
.
A device of this class is known from EP 0 534 245 B1 (corresponding to U.S. Pat. No. 5,377,969). This known device serves for feeding sheets stored in a stack, of a recording medium to a business machine, for example a printer, a copier or the like. The stack is disposed substantially horizontally. A drivable advance roller is in contact on the topmost sheet of the stack and is movably supported such that it can follow the height of the stack decreasing according to the output of the sheets. The advance roller engages frictionally the topmost sheet of the stack and slides it with its leading edge against an increasing obliquity adjoining the stack, which leads to the business machine. The leading edge of the topmost sheet runs up on this obliquity whereby the topmost sheet is lifted from the succeeding sheets of the stack and is isolated. In order for the leading edge of the topmost sheet to be able to run up on the obliquity, the leading edge must be bent up relative to the plane of the sheet. Since this bending-up depends on the stiffness of the sheet, the advance roller while it is being driven on this topmost sheet can move away from the obliquity. The advance roller in this way removes itself automatically according to the stiffness of the sheet as far from the obliquity such that the leading edge of the sheet is flexed under the effect of the advance force of the advance roller and can run up on the obliquity. The device thus adapts automatically to the stiffness of the sheets of the particular paper type used. While the known device has been found to be outstandingly well suited for the paper types customarily used for business machines, difficulties are encountered if an especially thin paper is used or if a paper of greater weight and thus greater stiffness is used. In the case of thin papers a problem lies therein that the pressure exerted by the advance roller resting in contact on the topmost sheet generates friction between the topmost sheet and the second sheet of the stack, which can lead to the undesirable dragging of the second sheet during the isolation of the top most sheet. In the case of sheets of high stiffness the advance force through the friction transferred from the advance roller onto the topmost sheet may in some cases not be sufficient to bend the sheet up and to push the leading edge up on the obliquity.
The invention is based on the task of improving a device of the class cited in the introduction such that a reliable isolation is possible for a relatively large range of paper types.
This task is solved according to the invention through a device with the characteristics of claim
1
.
Advantageous embodiments and further developments of the invention are specified in the dependent claims.
The essential idea of the invention comprises supporting the advance roller vertically freely movable such that it rests freely on the topmost sheet of the stack and can follow the decreasing height of the stack. If the advance roller is driven, it engages with frictional closure the topmost sheet of the stack in order to slide it in the advance direction. Initially the leading edge of the sheet is retained on the increasing obliquity since the stiffness of the sheet prevents the leading edge of the sheet from flexing and turning out upwardly in order to run up on the obliquity. While the topmost sheet is still retained in this way on the stack, the advance roller, due to its advance force which acts with frictional closure onto the topmost sheet, is moved away from the obliquity. The counter force, which moves the advance roller away from the obliquity, directed oppositely to the advance force causes, in addition, the vertical movement of the advance roller to be blocked. As soon as the advance roller is driven, it is consequently no longer freely vertically movable but is retained in its vertical position in which it rests on the topmost sheet.
This yields the advantage that the advance roller only needs to rest with a low weight on the stack. This low resting weight can be determined such that the contact pressure caused by this weight of the topmost sheet of the stack against the succeeding second sheet is low and no interfering friction between the topmost sheet and the succeeding second sheet of the stack occurs which might lead to the undesirable dragging of the second sheet during the advance of the topmost sheet. The device is thus suitable in particular also for the isolation of sheets of very thin paper. On the other hand, blocking of the vertical movability of the advance roller brings about as a result that the advance roller in spite of its low resting weight, is held firmly on the surface of the topmost sheet and during the driving cannot turn out from the surface of the topmost sheet upwardly. The advance force of the advance roller can therefore act unweakened with frictional closure onto the topmost sheet. It is thereby possible to isolate even sheets with great stiffness. Since through the measure according to the invention the isolation of sheets of a very thin paper with low stiffness as well as also the isolation of sheets of a paper of very high stiffness is promoted, the range of paper types, which can reliably be isolated, is considerably broadened.
The free vertical movability of the advance rollers is preferably realized thereby that the advance roller is supported on the free end of an arm with this free end of the arm being vertically movable. The arm is preferably pivotably supported in order to make possible the vertical movement of its free end. A special space-saving solution is obtained thereby that the arm is supported laterally of the stack and with its free end projects from the side over the stack. It is also possible to support the arm above the stack. An above the stack supported arm can also be telescopically longitudinally variable in order to permit a vertical movement of the advance roller disposed at its free end.
In a preferred embodiment the arm bearing the advance roller is relieved through a spring force which at least partially compensates the weight of the arm and of the advance roller. Through the dimensioning of this spring force the resting weight, and thus the resting pressure of the advance roller on the topmost sheet, can be freely selected and defined. It is in particular possible thereby to allow to rest the advance roller with an extremely low resting weight of, for example, only 50 to 100 g on the stack. Thereby only a very low friction between the topmost sheet and the succeeding second sheet of the stack is generated. The blocking of the vertical movement of the roller during the driving and during the advance ensures even with such a low resting weight a reliable frictional closure between advance roller and the topmost sheet. In a constructionally simple way the blocking of the vertical movement of the advance roller is brought about thereby that the counter force acting onto the advance roller is directed at least with one force component transversely to the movement of the arm bearing the advance roller and thereby causes a clamping of the movement of the arm.
The advance roller moves away from the obliquity preferably against the force of a reset spring. The reset spring causes at least that the advance roller is again reset toward the obliquity when the topmost sheet has been isolated and pulled from the stack, such that the advance roller rests on the succeeding next sheet of the stack. The reset spring preferably has an increasing spring characteristic such that the reset force increases with increasing distance of the advance roller from the obliquity. Thereby the path which the advance roller must travel in the case of sheets of relatively great stiffness until the leading edge of the sheet bends up and can run up on the obliquity, is not increased strongly.
In a further development the advance roller is not only movable against a reset spring but additionally also supported
Bantle Ludwig
Froechte Heinz
BDT Buro-und Datentechnik GmbH & Co. KG
Bower Kenneth W
Ellis Christopher P.
Foley & Lardner
Kleinke Bernard L.
LandOfFree
Device for separating sheets of a recording medium does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Device for separating sheets of a recording medium, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Device for separating sheets of a recording medium will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2611654