Sheet feeding or delivering – Feeding – With means to interrupt feeding
Patent
1982-08-06
1985-03-26
Schacher, Richard A.
Sheet feeding or delivering
Feeding
With means to interrupt feeding
B65H 712
Patent
active
045068801
DESCRIPTION:
BRIEF SUMMARY
This invention relates to machines for the high speed handling of sheets and more particularly to a banknote handling machine incorporating an apparatus for detecting the thickness of two or more superimposed banknotes passing through the machine.
Mechanical thickness detectors are known using a roller whose axis is displaced by the passage of a banknote or banknotes to cause an electrical contact to be made or broken if the displacement is such as to indicate the passage for superimposed banknotes.
These detectors have the disadvantage that the shafts which carry the banknote feed rollers are deflected by the passage of multiple notes which causes instability of the feeding assembly within the machine main frame resulting in incorrect thickness detection.
In the applicant's co-pending application No. PCT/GB81/00237 there is disclosed apparatus for detecting single or multiple sheets comprising: a surface on which the sheet or sheets is supported for movement in the plane of the sheets; a follower biased such that it normally abuts against the support and follows the profile of the surface of the support and the overlying sheet or sheets; a transducer responsive to the position of the follower to provide a thickness signal indicative of the linear displacement of the follower relative to the support due to the passage of the sheet or sheets; and a control circuit which compares the thickness signal with at least one stored threshold level signal to provide an output signal indicative of whether the detected thickness corresponds to that of a single sheet or multiple sheets; and characterized in that the control circuit includes means for repeatedly updating the or each stored threshold level signal from the thickness signal provided when there is no sheet between the support and the follower.
In some adverse conditions, a support frame for the transducer, the follower arm and the support surface was subject to warping, resulting in unsatisfactory performance.
An aim of the present invention is to provide an improved machine for detecting single or multiple sheets which is less sensitive to external influences. The invention consists in a sheet handling machine comprising: first and second parallel rotatable shafts mounted between fixed side frame members; first and second rollers carried by the first and second rotatable shafts respectively, the rollers mating to form a nip therebetween; the sheet thickness detecting apparatus comprising a transducer having first and second relatively movable parts, the relative movement of which results in a transducer output signal, the first and second parts being so mounted in the apparatus that the passage of a sheet between the rollers results in a signal indicative of sheet thickness, and a control circuit which compares the thickness signal with at least one stored threshold level signal to provide an output signal indicating whether the detected thickness corresponds to a single sheet or multiple sheets; characterized in that the first and second parts of the transducer are mounted on middle portions of the first and second rotatable shafts respectively, whereby the relative motion of the rotatable shafts is conveyed directly to the transducer.
Preferably, the transducer is mounted on the shaft by two plates, a first plate carrying the first part of the transducer at one end and being supported through a bearing by the first shaft, the first plate having an aperture through which the second shaft passes with a clearance, and a second plate carrying the second part of the transducer and being supported through a bearing by the second shaft, the second plate having an aperture through which the first shaft passes with a clearance.
In the preferred embodiment, the said two plates are joined by resilient means which allow a degree of movement between the plates in one direction only Conveniently, the resilient means in a spring strip; alternatively the resilient means may taken the form of a rubber strip.
The transducer is conveniently a linear variable differential t
REFERENCES:
patent: 3077983 (1963-02-01), Middleditch
patent: 4073488 (1978-02-01), Uchida
patent: 4095781 (1978-06-01), Kistner
patent: 4154437 (1979-05-01), Butcheck
patent: 4420747 (1983-12-01), Kistner
Dixon Christopher J.
Jenkins Stuart M.
De La Rue Systems Limited
Schacher Richard A,.
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