Sheet feeding or delivering – Feeding – Separator and conveyor
Reexamination Certificate
1999-03-30
2001-05-01
Bollinger, David H. (Department: 3651)
Sheet feeding or delivering
Feeding
Separator and conveyor
C271S010080, C271S010110, C271S121000, C271S125000, C271S035000
Reexamination Certificate
active
06224049
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to sheet feed apparatus for supplying sheets from a store to a sheet transport system and is applicable, for example, to the feeding of banknotes and other security documents.
DESCRIPTION OF RELATED ART
A well known approach, which is adopted in many banknote counters and sorters for feeding sheets from a store, employs a synchronous technique in which rollers with a high friction surface on part of their circumference are used to feed notes into a transport system at a fixed rate. The rollers are constantly rotating at a fixed speed and thus the picking action on the note is applied at a constant rate.
It is also known in some cases, as for example described in EP-A-0174200, to use an asynchronous technique using rollers having a high friction surface around their complete circumference. In this case, the speed of the rollers is modulated to provide control of the gap between the notes fed.
In most cases, it is usual to provide a separating mechanism forming part of the feed system to prevent more than one sheet from being fed into a sheet transport system which carries the sheets onto an outlet or other processing position. The separating mechanism is rotatably driven by the same motor driving the feed system to provide a linear speed to the sheet at the separating system essentially equal to that provided by the feed system.
An example of known sheet feeding apparatus is described in DE-A-19605106. In this case, a feed system is formed by a set of feed rollers, one or a number of which engage the topmost sheet in a stack to be fed. A contra-rotating roller is separately driven from the remainder of the feed system and acts in conjunction with the feed system to ensure that single sheets are fed on into a main transport system.
EP-A-0393589 illustrates a system for stream feeding sheets in an overlapped manner to a main transport system. In this case, sheets are withdrawn from a stack by a friction feed roller and fed to a downstream roller in the feed system, the downstream roller interacting with a separately driven roller to reduce the overlap between the sheets which are fed.
A major design consideration of each system is the range of sheet sizes which must be handled. This affects the distance between the first point of contact with the sheets of the feed system and the first pinch point of the sheet transport system. This distance must be less than the length (in the transporting direction) of the shortest sheet otherwise the sheet transport system will not pull the sheet clear of the store. Because of this, the first pinch point of the sheet transport system has to be mounted close to the sheet separation system with the result there is a tendency for sheets to be stream fed. This construction also causes space constraints on the height of the sheet store.
SUMMARY OF THE INVENTION
In accordance with a first aspect of the invention, a sheet feed apparatus for supplying sheets from a store to a sheet transport system comprises a feed system for withdrawing sheets from a store; a separator system, spaced from and independent of the feed system, to which sheets are fed by the feed system, the separator system being adapted to feed sheets singly to a sheet transport system, the separator system including a rotatable feed member for feeding sheets to the sheet transport system; and a control system for controlling operation of the feed system and the feed member of the separator system independently.
The invention is a new form of apparatus in which the feed system and separator system are completely independent of each other and independently operated, typically by separate motors. Thus, the feed system feeds sheets to the separator system, and the separator system feeds the sheets, independently of the feed system, to the transport system. In this way, the separator system becomes the main feeding element of the sheet feed apparatus. This allows the distance between the feed system and the sheet transport system to be extended. This should be contrasted with prior art arrangements in which separation is carried out by part of the feed system, sometimes in conjunction with a separately driven contra-rotating roller.
In some cases, the control system can stop rotation of the separator system for sufficient time, whilst the feed system is feeding a sheet, to enable the leading edge of an anticipated skew fed sheet to abut adjacent separator rollers of the separator system before the separator system is activated to transport on the essentially “straightened” sheet.
As has just been mentioned, two independent motors could be used to drive the feed and separator systems respectively although it would also be possible in some circumstances to use a single motor with suitable clutch and gear connections to the feed and separator systems. Furthermore, in some cases, the sheet transport system drive motor could also be used to drive the feed system.
The feed system could be driven either synchronously or asynchronously.
For example, the feed system could be activated in synchronism with, but a short time before, the separator system. Thus, the feed system will be designed to provide a fixed length feed shorter than the length (in the transporting direction) of the smallest sheet to be fed.
The feed system could be switched on and off at a fixed rate, each on period being less than that needed to feed the smallest sheet.
In a further example, the control system operates the feed system whereby sheets are fed in a continuous stream to the separator system which is then driven to control the feeding of separate individual sheets to the transport system.
Alternatively, the feed system may include at least one cyclically movable feed member part of whose surface defines a nudger portion, the control system continuously cyclically moving the feed member whereby sheets are only fed to the separator system when engaged by the nudger portion. With this approach, a series of synchronous nudges are provided to move the sheets against the separator system. The feed system could be defined by one or more rollers having relatively high friction inserts such as rubber inserts.
In an alternative approach, the apparatus further comprises a first sensor for sensing when the separator system receives a sheet from the feed system, the control system being responsive to the first sensor to deactivate the feed system when a sheet has been received by the separator system. This is an asynchronous mode of operation.
In all cases, sheets are fed in a non-overlapping manner, usually with a space between successive sheets.
Typically, the feed system will comprise one or more friction feed rollers or friction belts although other types of feed member such as vacuum belts or vacuum rollers could also be used.
The separator system may be implemented in a variety of ways. Preferably, however, the separator system acts as both the main feeding element of the apparatus and also as a gate to prevent additional sheets from being fed.
Typically, the apparatus further comprises a second sensor for sensing when a sheet is received by the sheet transport system, the control system being responsive to the output from the second sensor to cause the separator system to prevent further sheets being fed to the sheet transport system.
In one mode, the control system selectively stops the feed action of the separator system in order to ensure that only single sheets are fed to the sheet transport system. In an alternative mode, the control system selectively causes reverse operation of the separator system to ensure that only single sheets are fed to the sheet transport system. In this mode, modulating the motor current is used to vary the braking forces applied to the sheet.
In accordance with a second aspect of the present invention, a method of operating sheet feed apparatus according to the first aspect of the invention comprises repeatedly carrying out the following steps:
i) activating the feed system to withdraw a sheet from the store;
ii) after a predetermined interva
Hosking Steven Michael
Skinner John Alan
Bollinger David H.
De La Rue International Ltd.
Oliff & Berridg,e PLC
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