GB2077238A - Tensioning multilayer web fed through printer - Google Patents

Abstract

A paper feed for feeding a multilayer web (1) in a printer, in which the web (1) is fed towards the printing position (4) by an input feed (5) and away from the printing position by an output feed (6). The looped web (1) between the input feed (5) and the platen (2) is subjected to frictional drag by a blade (9) pivoted about an axis (10) at a point in advance of the platen (2) to ensure that the web (1) is maintained in a taut condition during its passage past the platen (2). <IMAGE>

Description

SPECIFICATION Improvements in or relating to paper feeding sThis invention relates to the feeding of webs of material such as multilayer paper webs.

In particular the present invention is concerned with the feeding of multilayer webs in the form of multi-part stationery in printers for producing printed output from a data processor or from a keyboard.

In such printers, the multipart stationery is fed past a platen and a printing head is arranged to print characters line by line on the web as it passes the platen. Suitable means, such as carbon paper interleaved between the layers of the web, is provided to effect printing on the under layers of the web. In order for the printing to take place correctly on all layers of the web it is necessary to ensure that all the layers pass round the platen without any creasing and that all the layers are maintained in registration with one another.

It is convenient to feed the multipart web to the platen for printing thereon and away from the platen, after printing, by means of a single pair of tractors having pins engaging in holes in opposite edges of the layers of the web. The in-feed part of the web is engaged by one side of the pair of tractors and the out-feed part of the web is engaged by the opposite side of the pair of tractors. A loop is formed in the web between the in-feed and out-feed and at the printing position the loop is supported by the platen. Since the infeed and out-feed in this arrangement are adjacent one another, the web in its passage around the loop is turned through a substantial angle and hence is subject to mis-registration and creasing as it passes the platen.

According to the invention apparatus for feeding a web consisting of a plurality of layers includes web feeding means having first means for feeding the web with its layers in registration toward an operating station and second means for feeding the web with its layers in registration away from the operating station; means for supporting the web at the operating station, the web passing as a slack loop from the first means toward the operating station; at least one member having a free edge movable to an operative position to urge the web into contact with a fixed surface at a position upstream of the operating station to impose a frictional restraint on the layers of the web and thereby maintain the layers under tension at the operating station.

An embodiment of the invention will be described with reference to the accompanying drawing which shows a wire printer having a paper feed in accordance with the present invention.

Referring to the drawing, a web 1 of multipart stationery is pulled past a bar platen 2 by means of a pair of tractors 3 (only one of which is illustrated) having pins on a belt engaging in perforations in the edges of the web. A matrix printing head 4 is mounted on a carriage (not shown) to effect printing on a portion of the web supported by the platen 2. The carriage is moved along a path parallel to the platen to enable a line of characters to be printed. The printing head 4 is provided with a plurality of wires having their operating ends arranged in a column or matrix formation adjacent the web 1, and the wires are selectively operable to form the outlines of desired characters on the web by impact through an inking ribbon (not shown) on the surface layer of the web.Interleaved between the paper layers of the web are layers of carbon paper whereby the impact of the wires of the printing head 4 result in printing on all the paper layers of the web.

In order to feed the web to the printing station in a controlled manner, the supply of web is engaged by the lower portion 5 of the pair of tractors 3 in the same manner that the out-feed of the web from the platen 2 is engaged by the upper portion 6 of the pair of tractors 3. In its passage from the lower portion 5 of the tractors, the web 1 passes between spaced guides 7 and 8 and thence to the platen 2, the length of the web 1 between the lower portion 5 of the tractors and the platen 2 is greater than the path length so that the web is not under tension but forms a loose loop of sinuous form between the guides 7 and 8, the guides being sufficiently spaced to permit this formation of the web. Hence the web is enabled to turn through a substantial angle prior to passage across the platen without being subjected to creasing of the layers or of mis-registration between the layers.However, it is necessary to ensure that the layers of the web are held in contact with one another and that the web is held in contact with the surface of the platen. This is accomplished by a member in the form of a blade 9 pivoted about an axis 10 and extending across the web. The blade is resiliently urged toward a surface of a fixed bar 11. The web passes between the free edge of the blade and the bar 11 and therefore is subjected to a frictional restraint which is effective to apply a tension to the layers of the web as they pass over the platen to maintain the layers in contact with one another and the web in contact with the platen. The blade 9 may be held away from the bar 11 to facilitate initial loading of the web into the feed mechanism.

Also the guide 8 may be movable to facilitate loading of the web.

It will be realised that the blade 9 could, if desired, be of resilient material and in this case there would be no need for it to be pivoted about the axis 10. The blade 9 could, for example, simply be mounted on a member which may be positioned either so that the blade 9 is in an operative position or, so that it is in a retracted position to allow loading of the web. It will also be realised that the blade 9 need not have a single free edge for engaging the web but could, for example, having a plurality of finger-like projections engaging the web at spaced locations across its width. Furthermore, the blade could, if desired, comprise a number of narrower blades supported on a common pivot.

Claims (6)

1. Apparatus for feeding a web consisting of a plurality of layers including, web feeding means having first means for feeding the web with its layers in registration toward an operating station and second means for feeding the web with its layers in registration away from the operation station; means for supporting the web at the operating station, the web passing as a slack loop from the first means toward the operating station; at least one member having a free edge movable to an operative position to urge the web into contact with a fixed surface at a position upstream of the operating station to impose a frictional restraint on the layers of the web and thereby maintain the layers under tension at the operating station.

2. Apparatus for feeding a web as claimed in Claim 1, in which the operating station includes printing means and the web supporting means includes a platen.

3. Apparatus for feeding a web as claimed in Claim 1 or 2, in which the movable member is in the form of a single blade having a free edge extending across the web.

4. Apparatus for feeding a web as claimed in Claim 3, in which the free edge of the blade includes a plurality of finger-like projections.

5. Apparatus for feeding a web as claimed in Claim 3 or 4, in which the blade is pivoted about the axis.

6. Apparatus for feeding a web consisting of a plurality of layers, constructed and arranged,to operate substantially as hereinbefore described with reference to the accompanying drawings.