GB2122546A - Stencil loading in a stencil duplicator - Google Patents

Abstract

A stencil loading device includes a pivoting plate 22 and a top member 24, also pivoted, and arranged such that during pivoting the rear of the plate 22 lifts a stencil portion 34b clear of a coded stencil-holding pin 14 to allow the stencil to be entrained by the mounting pin 32 of a stencil carrier. The coded stencil-holding pins (e.g. 14) are visible from outside the stencil loading device and are designed to be incapable of accepting the stencil 34a-34b in an inverted configuration. <IMAGE>

Description

SPECIFICATION Stencil loading in a stencil duplicator The present invention relates to the loading of a stencil automatically onto the stencil carrier of a stencil duplicator.

Our UK Patent No. 1,560,153 discloses a stencil loading device in which the stencil can be inserted manually into a holding mechanism, ready to be subsequently moved automatically into the path of a movable stencil carrier to be entrained by that carrier for automatic loading at an appropriate time during the operating cycle of the duplicator. The stencil holding mechanism disclosed in said UK Patent No. 1,560,153 includes means for correctly aligning the leading edge of the stencil heading strip with the holding mechanism, and means for holding the stencil heading in the appropriate position once the operator has inserted it into the stencil holding mechanism.

The device described and illustrated in UK Patent 1 5601 53 has certain disadvantages which are to be overcome by the present invention.

Firstly, the stencil retaining means which hold the stencil heading strip in the appropriate position relative to the stencil holding members are saw-tooth ramps concealed within the stencil loading device such that the stencil, once it has been inserted in the holding mechanism, can only be removed by lifting the stencil cover and pulling the stencil forward over the saw tooth ramps in order thereby to clear the stencil heading strip from the holding mechanism. Bearing in mind that it is possible for the stencil to be inadvertently loaded in the inverted configuration or for a desired sequence of stencils to be broken inadvertently, this difficulty of removal provides problems where the operator is unfamiliar with stencil duplicating or is under such pressure of work that carelessness sets in.

It is therefore an object of the present invention to provide a stencil loading device for a stencil duplicator including means for ensuring that the stencil is only able to be loaded one-way up and that, if for any reason that particular stencil needs to be removed, it can be removed without needing to lift the cover of the duplicator where the stencil holding mechanism (as is disclosed in our said British Patent No. 1,560,153) incorporated in the duplicator cover. It is clearly undesirable for the cover to be lifted during printing since this would either constitute a hazard to the operator if there is no interlock to stop the duplicator once the cover lifts, or will interrupt the printing run if there is an automatic interlock between the cover and the drive motor.

Accordingly, the present invention provides a stencil loading device comprising first and second holding members defining a nip to receive a stencil heading strip and movable from a first position in which they hold the stencil heading strip clear of the path of a stencil carrier to a second position where they hold the stencil heading strip in position for entrainment by the movable stencil carrier; and coded stencil-holding means to co-operate with an appropriately designed stencil heading strip to ensure that the stencil heading strip is not in an inverted configuration, and is correctly centered with respect to the intended position on the stencil carrier, said coded stencil holding means comprising relief formations visible to an operator from outside the stencil loading device during normal operation of the stencil loading device.

Preferably the relief formations comprise at least two pins arranged one to either side of the centre line of the direction of stencil advance into the nip between the stencil holding members.

More preferably, the holding pins may be coded by being of characteristic shape and/or arrangement to either side of the centre line of the stencil path into the holding mechanism. More preferably still the pins are of characteristic shape and size, for example one being smaller than the other and being circular in plan view and the other being rectangular or square.

In order that the present invention may be more readily understood the following description is given, merely by way of example, with reference to the accompanying drawings in which: Figure 1 is a perspective view of a stencil duplicator cover including the stencil loading device according to the present invention; Figure 2A is a vertical sectional view taken on the line ll-ll of Fig. 1, when the stencil loading device is in the configuration illustrated in Fig. 1 and waiting to receive the next stencil; and.

Figure 2B is a view similar to Fig. 2A, but showing the stencil holding members in their alternative configuration in which the stencil heading strip is being entrained by the pins of a stencil carrier.

The apparatus shown in Fig. 1 comprises a cover 10 which is pivotable about a hinge (not shown) at the left hand side of the drawing and rests on a plate 1 2 on which two differently-shaped stencil-holding pins 14 and 1 6 are formed. As shown in Fig. 1, the pin 14 is of circular plan view and has a chamfer 1 8 on its side over which the stencil will, in use, be moved by the operator, and likewise the pin 16, although of rectangular planform, has a chamfer 20. The pins 1 4 and 1 6 are formed on forwardly projecting tongue portions 1 2a and 1 2b of the plate 12. A further plate 22, pivotally mounted as can be seen from Figs. 2A and 2B, is provided with appropriate recesses to co-operate with the tongues 12aand 12b.

Reference to Figs. 2A and 2B will show that the movable plate 22 of Fig. 1 forms the lower of two stencil holding members, the upper stencil holding member comprising a guide bar 24 which is supported on end brackets 26 which are in turn pivotable about the same pivot axis 28 as the lower pivotable plate 22.

Although in this case the larger cross-section rectangular ramp pin 1 6 and the smaller cross-section circular pin 14 are equidistant from the centre line of the path of intended stencil advance into the nip between the cover and upper stencil holding members 22 and 24, it is within the scope of the present invention for their coding in relation to an intended stencil to be achieved by alternatively or additionally positioning the two pins at different spacings from the centre line or by providing more than one such pin to one or both sides of the centre line (e.g. two identical pins to one side and a third similar pin to the other side). The stencil heading strip must however be provided with a hole arrangement corresponding to the pin arrangement used.

The stencil-carrying cyclinder 30 (in this case the upper of two parallel cylinders in a multi-cylinder duplicator) is shown in Figs. 2A and 2B and the mounting pins 32 which hold the stencil on the cylinder 30 are clearly shown in Fig. 2B.

Although a detailed description will now be given of the operation of the apparatus illustrated in Figs. 1, 2A and 2B, it should first of all be noted that the pins 32 correspond to the pins 7 of UK Patent No. 1,560,153, and that the pivotable plate 22 and pivotable bar 24 correspond to the lower and upper stencilholder members 3 and 2, respectively, of said Patent.

While one stencil is already entrained on the cylinder 30 and is being used to print the required number of copies, the operator takes the next stencil and places it on the fixed plate 1 2 so that a circular hole in the stencil heading strip co-operates with the circular cross-section smaller pin 14 at the righthand side of the stencil heading strip and a rectangular hole at the lefthand side of the heading strip co-operates with the larger rectangular pin 16.

During this time the pivotable plate 22 and bar 24 are in the Fig. 2A configurations.

The two stencil holding pins 14 and 16, pin 14 of which can readily be seen in Figs.

2A and 2B, serve both to hold the stencil in place once the operator has mounted it on the fixed plate 12, and also to provide a means of registering the leading edge of the stencil heading strip correctly, provided the stencil heading strip has been designed to conform with certain standard requirements for a stencil to be used with the stencil loading device in accordance with the present invention. It is envisaged that several different types of stencil will be made with the appropriate configuration of identifying holes to co-operate with the identifying pins 14 and 16 so that each of them can, if desired, be used with the stencil loading device illustrated in Figs. 1, 2A and 2B.Of course the stencil heading strip will have a different set of holes on the stencil carrier which serve to mount the stencil heading strip on one or more types of duplicator cylinders such as cylinder 30 with its pins 32.

These mounting pins 32 and holes may well conform to a standard layout common to several makes of stencil duplicator.

As indicated above, a third function of the pins 1 4 and 1 6 is that they are coded to ensure that the stencil heading strip will only be capable of being mounted on those pins, and hence introduced into the stencil loading device, when in the correct configuration.

Clearly, if the stencil heading strip is inverted so that the righthand hole is the one of rectangular cross-section which in this case is clearly much larger than the pin 14 of circular cross-section, then the smaller hole of circular cross-section will be incapable of receiving the large lefthand pin of rectangular cross-section and the operator will immediately know that this particular stencil is in the inverted configuration and will be unable to mount the stencil on the holding pins in that configuration.

A considerable advantage of the device according to the present application is that the two coding pins 14 and 16, or any other coded holding means which can be used within the scope of the present invention as defined by the claims, can be readily visible from outside the machine so that an uncertain operator can check visually before inserting the leading end of the stencil heading strip into the nip between the lower holding plate 22 and the upper holding bar 24.Furthermore, the fact that these pins 14 and 16 are accessible from the exterior facilitates removal of the stencil heading strip from the stencil locating pins, for example if the operator has taken an incorrect stencil out of sequence and wishes to rectify the sequence of stencils when using the stencil duplicator to print sheets to be collated into a given sequence requiring the delivered copy sheets to present the successive images in the correct sequence.

At the end of the particular printing run already under way, the stencil on the cylinder 30 will be ejected, preferably automatically using the stencil ejecting system disclosed in our UK Patent No. 1,502,522, and then the duplicator is ready to receive the fresh stencil which, by now, the operator has placed on the stationary plate 1 2.

At the appropriate instant when loading of that new stencil is required, the upper stencil holding bar 24 and the lower stencil holding plate 22 are pivoted from the Fig. 2A position into the Fig. 2B position to guide the leading end of the stencil down into the path of the pins 32 on the rotating cylinder 30.

Fig. 2B shows precisely this arrangement and illustrates the fact as the leading end 34a of the stencil is entrained by the pins 32, dragging the stencil through the nip between the upper stencil holding bar 24 and the lower stencil holding plate 22, the portion 34b of the stencil heading strip adjacent the top of the limp stencil material is lifted off the holding pins 14 and 1 6 by the pivoting action of the plate 22 raising its rearmost part to a position substantially flush with the peaks of the pins 14 and 1 6 (pin 1 4 being the only one visible in Fig. 2B).As the pins 32 pass along their anti-clockwise path on the periphery of the cylinder 30, the entire stencil is dragged through the nip between the bar 24 and the plate 22 to smooth that stencil onto the surface of the ink screen associated with the stencil carrier supported on the cylinder 30.

To summarize the advantages of the present system over and above the system disclosed in our said Patent No. 1,560, 1 53, these are: (a) The operator has the possibility of visually observing alignment of the stencil while attaching it to the holding pins 14, 1 6 of the stencil loading device 12, 22, 24; (b) it is not possible for the stencil to be located in the inverted configuration; (c) it is not possible for the stencil to be mounted in the loading mechanism 12, 22, 24 in any position laterally displaced from that which it requires for entrainment by the pins 32; and (d) The stencil can be removed by the operator, before loading, if the sequence has been inadvertently lost, or if for any other reason replacement is required.

Although, in the present description, it is indicated that the stencil loading mechanism is incorporated on the top cover of the duplicator, this could of course be incorporated on any other component of the machine, provided the operator still has the opportunity of observing the stencil holding pins or other coded holding means.

Claims (11)

1. A stencil loading device comprising first and second holding members defining a nip to receive a stencil heading strip and movable from a first position in which they hold the stencil heading strip clear of the path of a stencil carrier to a second position where they hold the stencil heading strip in position for entrainment by the movable stencil carrier; and coded stencil holding means to cooperate with an appropriately designed stencil heading strip to ensure that the stencil heading strip is not in an inverted configuration, and is correctly centered with respect to the intended position on the stencil carrier, said coded stencil holding means comprising relief forma tions visible to an operator from outside the stencil loading device during normal operation of the stencil loading device.

2. A stencil loading device according to claim 1, wherein said relief formations com prise at least two pins arranged one to either side of the centre line of the direction of stencil advance into the nip between the sten cil holding members.

3. A stencil loading device according to claim 2, wherein said pins are asymmetrically spaced from the centre line of the centre line of the path of stencil advance into the nip between said stencil holding members.

4. A stencil loading device according to claim 3, wherein there are at least three of said pins.

5. A stencil loading device according to any one of claims 2 to 4, wherein said relief formations comprise at least two stencil-hold ing pins of different cross-sectional shape.

6. A stencil loading device according to any one of claims 2 to 5, wherein said pins are not of the same size as one another.

7. A stencil loading device according to any one of claims 2 to 6, wherein said pins have chamfered edges on the side facing away from said holding members.

8. A stencil loading device according to any one of the preceding claims, wherein one of said stencil holding members comprises a pivotable plate having a portion which, during pivoting of the plate from its first position to its said alternative position, lifts the stencil heading strip clear of said relief formations to disengage the stencil heading strip therefrom and to leave it free for entrainment by said movable stencil carrier.

9. A stencil loading device according to any one of the preceding claims, and includ ing a pivotable cover to conceal said second stencil member and at least a part of said first stencil holding member.

10. A stencil loading device according to any one of the preceding claims, when incor porated in a pivotable top cover of a duplica tor.

11. A stencil loading device substantially as hereinbefore described with reference to, and as illustrated in, the accompanying draw ings.