GB2165821A - Sheet feeding arrangement - Google Patents

Abstract

In a copying machine including an internal tray for storing a stack of copy sheets, and a curved sheet guide (29) for guiding sheets therefrom through approximately 180 DEG before they are fed along a sheet path into the processor of the machine, an alternative feeding arrangement feeds sheets through an input chute (43) directly to the processor (i.e. without turning them through 180 DEG ) from an external copy sheet tray (50) along a first path or from an external copy sheet stack holder (60) along a second path, the first and second paths being defined by guide members (53 and 62 respectively) and converging into the input chute (43). This enables the use of different types of copy paper. <IMAGE>

Description

SPECIFICATION Copying machine This invention relates to a copying machine of the kind which includes an internal storage tray for storing a stack of copy sheets, means for feeding sheets from the stack in a first direction, and a sheet guide for guiding sheets as they are fed such that they turn through approximately 180 for feeding along a sheet path into the processor of the machine in a second direction generally opposite to the first direction. The sheet feeding arrangement of a machine of this kind is described in our European Patent Application No. 83 305 598.1.

In the sheet feeding arrangement described in the above mentioned patent specification, there are two storage trays for copy sheets, which provide alternative supplies of copy paper sheets, for example of different sizes. The provision of two trays gives added flexibility to the machine, but in order to use further alternative types of copy paper such as paper of different sizes, weights or colours, it is necessary for the operator to open the machine front cover, pull out a tray, remove the existing paper, adjust the stops (if necessary) to the new size, insert the new sheets, replace the tray and close the cover. This can be rather inconvenient if it is often desired to make, for example, small numbers of copies on various different types of paper.

The present invention is intended to overcome this inconvenience, and provides a machine of the kind specified which includes alternative sheet feeding means including convergent first and second sheet entry paths into the processor in the second direction, an external copy sheet tray from which copy sheets may be fed along the first sheet entry path, and an external copy sheet stack holder from which copy sheets may be fed along the second sheet entry path.

The copying machine of the invention has the advantage of considerably increased flexibility at minimal extra cost, and has the additional advantage that an external copy sheet storage bin can be added to the machine to feed copy sheets through the alternative sheet feeding means, to provide, for example, a high capacity store of copy sheets.

A copying machine in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which Figure 1 is a diagrammatic cross-sectional view of a xerographic copying machine in accordance with the invention; Figure 2 is an enlarged diagrammatic cross-section of the alternative sheet feeding means which characterises the invention.

Referring first to Figure 1 there is shown a xerographic copying machine incorporating the present invention. The machine includes a photoreceptor drum 1 mounted for rotation (in the clockwise direction as seen in Figure 1) to carry the photoconductive imaging surface of the drum sequentially through a series of xerographic processing stations: a charging station 2, an imaging station 3, a development station 4, a transfer station 5, and a cleaning station 6.

The charging station 2 comprises a corotron which deposits a uniform electrostatic charge on the photoreceptor. A document to be reproduced is positioned on a platen 13 and scanned by means of a moving optical scanning system to produce a flowing light image on the drum at 3. The optical image selectively discharges the photoconductor in image configuration, whereby an electrostatic latent image of the object is laid down on the drum surface. At the development station 4, the electrostatic latent image is developed into visible form by bringing into contact with it toner particles which deposit on the charged areas of the photoreceptor.Cut sheets of paper aremoved into the transfer station 5 in synchronous relation with the image on the drum surface and the developed image is transferred to a copy sheet at the transfer station 5, where a transfer corotron 7 provides an electric field to assist in the transfer of the toner particles thereto. The copy sheet is then stripped from the drum 1, the detachment being assisted by the electric field provided by de-tack corotron 8.

The copy sheet carrying the developed image is then carried by a transport belt system 9 to a fusing station 10.

After transfer of the developed image from the drum, some toner particles usually remain on the drum, and these are removed at the cleaning station 6. After cleaning, any electrostatic charges remaining on the drum are removed by an erase corotron 11. The photoreceptor is then ready to be charged again by the charging corotron 2, as the first step in the next copy cycle.

The optical image at imaging station 3 is formed by optical system 12. A document (not shown) to be copied is placed on platen 13, and is illuminated by a lamp 14 that is mounted on a scanning carriage 15 which also carries a mirror 16. Mirror 16 is the full-rate scanning mirror and a full and half-rate scanning system. The full-rate mirror 16 reflects an image of a strip of the document to be copied onto the half-rate scanning mirror 17. The image is focussed by a lens 18 onto the drum 1, being deflected by a fixed mirror 19. In operation, the fullrate mirror 16 and lamp 14 are moved across the machine at a constant speed, while at the same time the half-rate mirrors 17 are moved in the same direction at half that speed. At the end of a scan, the mirrors are in the position shown in a broken outline at the left hand side of Figure 1.

These movements of the mirrors maintain a constant optical path length, so as to maintain the image on the drum in sharp focus throughout the scan.

At the development station 4, a magnetic brush developer system 20 develops the electrostatic latent image. Toner is dispensed from a hopper 21 by means of a rotating foam roll dispenser 22, into developer housing 23. Housing 23 contains a twocomponent developer mixture comprising a magnetically attractable carrier and the toner, which is brought into developing engagement with drum 1 by a two-roller magnetic brush developing ar rangement 24.

The developed image is transferred, at transfer station 5, from the drum to a sheet of copy paper (not shown) which is delivered into contact with the drum by means of a paper supply system 25.

Paper copy sheets are stored in two paper trays, an upper, main tray 26 and a lower, auxiliary tray 27. The top sheet of paper in either one of the trays is brought, as required, into feeding engagement with a common, fixed position, sheet feeder 28. Sheet feeder 28 feeds sheets around curved guide 29 for registration at a registration poing 30.

Once registered, the sheet is fed into contact with the drum in synchronous relation to the image so as to receive the image at transfer station 5.

The copy sheet carrying the transferred image is transported, by means of vacuum transport belt 9, to fuser 10, which is a heated roll fuser. The image is fixed to the copy sheet by the heat and pressure in the nip between the two rolls of the fuser. The final copy is fed by the fuser rolls along output guides 31 into catch tray 32, which is suitably an offsetting catch tray.

After transfer of the developed image from the drum to the copy sheet, the drum surface is cleaned at cleaning station 6. At the cleaning station, a housing 33 forms with the drum 1 an enclosed cavity, within which is mounted a doctor blade 34. Doctor blade 34 scrapes residuai toner particles off the drum, and the scraped-off particles then fall into the bottom of the housing, from where they are removed by an auger 35.

Referring now to Figure 2, the curved guide 29 turns copy sheets, fed from the paper supply system 25, through an angle approaching 1800. This arrangement provides a compact paper path by feeding copy sheets initially from left to right to remove them from one of the paper trays, then feeding them from right to left along a sheet path through the xerographic processor. The copy sheets are brought into contact with the drum 1 at transfer station 5 (Figure 1). Copy sheets fed around guide 29 are first taken up by drive rolls 41, and are then registered at registration point 30 which comprises the nip between registration and feed rolls 42.

In the alternative copy sheet feeding mode, copy sheets are fed not from trays 26 or 27, but through a chute 43 adjacent the upper end of guide 29, the lower wall 44 of chute 43 being formed as an extended lip along the upper edge of guide 29. The wall 44 and chute 29 can be integrally formed, for example as an aluminium extrusion. The upper wall 45 of chute 43 extends from an input end 46, and provides a sheet guiding surface from input end 46, through chute 43, and into the nip between registration and feed rolls 42. The portion 47 of wall 45, between the input chute 43 and the rolls 42, also acts as a guide surface for copy sheets fed from the paper trays by rolls 41.

Single copy sheets are introduced into the alternative sheet fed arrangement by placing them on a tray 50, most of which projects outside the right hand wall 51 of the copying machine. The inner, lowermost end 52 of the tray 50 terminates adjacent one end of a guide member 53, the other end of which terminates alongside the input end 46 of the upper wall of the input chute 43. A pair of registration and feed rolls 54 form a nip adjacent the mid portion of guide member 53, so that the single sheet can be placed on the tray 50 and can be inserted until its leading edge abuts the nip between rolls 54. On starting a copy cycle of the machine in its alternative sheet feeding mode, rolls 54 feed the sheet through input chute 43 and along the underside of guide surface 47 untii the leading edge of the sheet arrives at the registration point 30.From that point on, the usual xerographic process ensues.

By making use of the alternative sheet feeding arrangement just described, a wide variety of sizes, colours and weights of paper, as well as other sheet materials such as transparencies, may conveniently be fed into the machine to receive a xerographic copy.

In addition to the single sheet feeding facility just described, the alternative sheet feeding arrangement of the present invention also enables the use of an additional copy sheet storage bin, such as a high capacity bin 60 shown in Figure 1. Such a supply bin may be a free standing bin arrangement adapted to be brought alongside the copying machine and secured to it, and able to carry, for example, five reams (2,500) of copy sheets. A retard feeder 61 is mounted on the top of the storage bin 60 for feeding sheets from the bin towards the input chute 43. A guide member 62 guides sheets fed from the bin 60 to the nip between feed rolls 63 and thence into a lower entrance mouth of input chute 43 formed between the lower wall 44 of the input chute and an extended lip 64 of the guide member 53. The use of a high capacity bin further extends the capabilities of the copying machine by enabling long copy runs without the need to reload the paper trays.

Claims (4)

1. Copying machine including an internal storage tray for storing a stack of copy sheets, means for feeding sheets from the stack in a first direction, a sheet guide for guiding sheets as they are fed such that they turn through approximately 1800 for feeding along a sheet path into the processor of the machine in a second direction generally opposite to said first direction, alternative sheet feeding means including convergent first and second sheet entry paths into the processor in the second direction, an external copy sheet tray from which copy sheets may be fed along the first sheet entry path, and an external copy sheet stack holder from which copy sheets may be fed along the second sheet entry path.

2. The copying machine of claim 1 wherein said sheet guide is the internal surface of a curved member having said entrance aperture adjacent its end closest to the processor.

3. The copying machine of claim 2 wherein said entrance aperture is within an entrance chute, one wall of the chute being formed integrally with said curved member.

4. A copying machine substantially as hereinbefore described with reference to the accompanying drawings.