GB2127384A - Corner-registration by a pair of sensors spaced from a corner - Google Patents

Abstract

A document handler in which documents are inserted manually one at a time and registered prior to being advanced through the document handler. A pair of sensors 46 must be satisfied before the documents can be advanced, these sensors being positioned to detect the leading edge and one side edge of the document at locations spaced from the corner between the edges, so that a document can be correctly registered even if it has a damaged corner. <IMAGE>

Description

SPECIFICATION Improvements in document handlers This invention relates to document handlers and particularly to document handlers in which documents are manually inserted thereinto one at a time and registered prior to being fed through the document handler. Registration may be entirely manual or it may be assisted by a mechanical registration device.

In so-called semi-automatic document handlers such as used in the Xerox 3450 copier, documents are manually inserted against end and side registration stops and when registered can be fed automatically through the document handler. A sensor provided in the registration corner must be satisfied before the automatic feed mechanism can be actuated. However, since the corner of a document may be missing or damaged the setting to meet the specified registration tolerance makes it impossible to feed documents with damaged corners unless the document is turned to present a different (undamaged) corner or the corner repaired. Further, by pressing the document into the registration corner against one of the stops, proper registration can be sensed although the document is skewed and buckled.

In order to alleviate this problem, in accordance with the present invention two sensors are provided which are positioned to detect the leading and side edges respectively of the document at locations spaced from the corner.

In order that the invention may be more readily understood, reference will now be made to the accompanying drawings, in which: Figure 1 is a schematic side elevation of a copier incorporating a semi-automatic document handler according to the invention, Figure 2 is a perspective view from above of the document handler with the cover removed, Figure 3 is a schematic cross-section of the document handler taken from one side, Figures 4 and 5 are enlarged details of the view shown in Fig. 3, Figure 6 is a perspective scrap view taken from the rear showing the input end of the document handler with the cover removed, Figure 7 is another perspective scrap view, taken from the front, of the input end showing the pre-registration and advancing mechanism in greater detail, Figures 8 to 10 illustrate stages in the operation of the pre-registration and advancing mechanism, Figure ii is a schematic side view of the document handler illustrating one mode of making copies, and Figure 12 is a view like that of Fig. 11 illustrating a second mode of making copies.

Referring first to Fig. 1 there is shown a xerographic copying machine incorporating a semi-automatic document handler 40 according to the present invention. The machine includes a photoreceptor drum 1 mounted for rotation (in the clockwise direction as seen in Fig. 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 1 3 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 rotation 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 are moved 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 an a.c. 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 a.c. 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 1 2. 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 which also carries a mirror 1 6. Mirror 1 6 is the full-rate scanning mirror of a full and half-rate scanning system.The full-rate mirror 1 6 reflects an image of a strip of the document to be copied onto the half-rate scanning mirrors 1 7. The image is focussed by a lens 1 8 onto the drum 1, being deflected by a fixed mirror 1 9. In operation, the full-rate mirror 1 6 and lamp 1 4 are moved across the machine at a constant speed, while at the same time the half-rate mirrors 1 7 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 Fig. 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 two-component 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 arrangement 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 separator/feeder 28. Sheet feeder 28 feeds sheets around curved guide 29 for registration at a registration point 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, via output nip rolls 31 a.

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 residual 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.

As mentioned above, sheets 5 may be fed from either the main tray 26 or the auxiliary tray 27. The auxiliary tray is of larger size than the main tray, enabling a wide choice of paper sizes and types to be fed from it. The trays are physically located in the lower part of the machine below the photoreceptor drum 1.

A semi-automatic document handler 40 is arranged over the platen 1 3 by which documents inserted manually at the right-hand side are fed on to the platen for copying and then fed off the platen into a catch tray 42 at the left-hand side after copying. Manually inserted documents are pre-registered with the aid of a registration device prior to feeding on to the platen. Exposure of the document may be by driving the document at a constant velocity past the optical system 1 2 with the latter held stationary in the position shown in full lines in Fig. 1 or by registering the document on the platen and scanning the optical system 1 2 thereacross as described above.In a preferred form, where multiple copies of a single docu ment sheet are registered, the first copy is made in constant velocity mode (stationary optics) as the document is fed on to the platen and subsequent copies are made in scanning mode (moving optics) with the document stationary.

Input is by a tray 41 which slopes downwardly towards the platen 13. The input registration area incorporates a document registration aid (nudger) consisting of a gravity ball 43 which contacts with a driven wheel 44.

The ball 43 overlies the tray 41 and the wheel 44, angled at about 30 to the tray rear edge, projects through an aperture in the tray.

The nudger 43, 44 corner registers the document against a fixed side edge 47 at the rear of the tray and a retractable front edge or gate 48.

An input sensor 45 detects the lead edge of a document inserted into the tray 1 to activate the nudger 43/44 and alert the logic to the presence of a document.

Correct registration of the document is determined by a pair of optical sensors 46 (both seen in Fig. 6) positioned at the extreme back left hand corner of the input registration area.

The sensors 46 are positioned just inboard of the side and front registration edges 47, 48 respectively at locations spaced from the corner. In a preferred embodiment the sensors have infrared sources above the tray 41 and detectors under the tray and are spaced 10 to 15mm from the corner and 1 and 1.5mm inboard of the respective registration edges 47, 48. When correctly registered, the front edge of the document lies against input registration gate 48 beneath a pair of raised polyurethane coated driven nip rollers 49. Activation of both sensors 46 deenergises the nudger.

When correct pre-registration has been achieved and the handler is ready to accept a document, a vidual indication, e.g., illumination of an LED 69, is given to the operator and a solenoid 90, which actuates the input nip roll 49 and the front registration gate 48 in that order, is energised by pressing the copier's start print button, or in the case of subsequent documents by instant start actuated by the sensors 46 The solenoid 90 actuates the input nip rolls 49 and the front registration gate 48 through a mechanism 91 designed to ensure that the nip rolls 49 engage and grip the document against the idler rolls 50 before the gate 48 is raised.In this way possible deskewing and pre-feeding of the document by the nudger 43, 44 and/or by sliding under gravity down the tray 41 as the gate is raised and before it is positively gripped by the nip rolls, is avoided. In this respect it should be noted that in the case of second and subsequent documents in a sequence the solenoid 90 is operated immediately correct registration is sensed and thus the nudger 43, 44 is still rotating when the solenoid is operated. Deskewing will lead to incorrect positioning of the document over the platen and pre-feeding may activate the sensor 53 early causing a copy sheet (feeding of which is initiated by the sensor 53) to be fed out of registration with the image of the photoreceptor 1.

The mechanism 91 is shown in Fig. 7 and its operation is illustrated in Figs. 8 to 1 0.

Two advancing rolls 49 are mounted on a shaft 92 carried by a pair of arms 93 pivotally mounted on belt input roll shaft 56a. The rolls 49 are normally held above the tray surface 41 by a cam 94 mounted on a shaft 95 which is biassed to the position shown in Fig.

7 by a spring 96. Lowering of the rolls 49 on to the tray is effected by actuation of the solenoid 90 rotating the cam 94 clockwise as seen in Fig. 7 through a cable 97 connected to a quadrant plate 98 fixed to the shaft 95.

The registration gate 48 is mounted on the shaft 95 but so that it will not be raised until the rolls 49 have been lowered against the tray 41, it is rotatably mounted on the shaft 95 by means of an annular mounting 99 and is rotated by a pin 100 on the shaft 95 which moves in a slot 99a in the mounting 99.

Thus, as shown in Fig. 8 during insertion of a document Don the surface 41, the rolls 49 are raised by the cam 94, which carries a roller 94a for smooth operation, and the gate 48 is lowered with the pin 100 positioned as shown. During initial rotation of the shaft 95, the rolls are lowered by their own weight, which is chosen to provide the desired force on the document D, while the pin moves freely in the slot 99a as shown in Fig. 9.

During the final part of the shaft rotation the pin 100 engages the mounting 99 and lifts the gate 48 as shown in Fig. 10.

Once the nip rolls 49 are lowered and the gate 48 raised, an electro-magnetic clutch is then energised, driving the platen transport 51 and nip rolls 49. Simultaneously, the nudger is reenergised during the passage of the document under sensors 46. The nip rolls 49 transport the document to the platen transport belt 52 at a nominal 0.993x photoreceptor surface speed. Positioned just forward of the registration gate 48 is another optical sensor 53 which senses the lead edge of the moving document, and initiates the copy paper transport system and the processor cycle.

The document is transported across the platen 1 3 by a white 370mm wide friction drive belt 52 at a nominal 0.993x photoreceptor surface speed (to give the same 1.007 magnification achieved by the scanning optics). The input and output transport rolls 56, 57, over which the belt 52 is entrained, are positioned a nominal 0.76mm + thickness of belt above the platen 1 3.

Three gravity rolls 58 apply a nip between the belt and platen and maintain drive across the platen. Belt tensioning and replacement is achieved by adjustment of the roller 57 at the output end of the platen.

There are also two tracking guide rollers 59 (only one shown), one either side of the belt.

A pivoting edge 60 is arranged across the end of the platen glass. This is raised to register the document in a multiple copy run and then lowered for sheet ejection into the catch tray. For a single copy the edge remains lowered and the copy is made by transporting the document across the platen in continuous movement at a constant velocity.

To aid the ejection of the document onto output tray 42 two cellular rubber rolls 61 provide a nip at the top of the output tray ramp 62. The roll shaft is driven from the output platen transport roll 57, the surface speed being the nominal transport speed.

There is a non-structural plastic outer cover 54 and a structural plastic inner cover which covers the complete underside of the document handler only allowing the platen transport belt through, its visible surface being painted white. Accessibility to the input registration assembly is gained by removing the document handler top cover 54.

The document handler can hinge open to approximately 55 by lifting up the front edge of the top cover. This allows the platen to be used for copying books, special documents etc. A pair of compression springs 64 (Fig. 2) counterbalance the raised document handler.

The springs 64 are designed so that the document handler is self-supporting at any position from 5" to a maximum opening of 55 , but will close from a position less than 5".

Drive for the document handler is taken from a pulley 70 on the optics drive shaft of the copier via a timing belt 71 to a pulley 72 on the document handler drive shaft 73. The drive shaft 73 has mounted on it an electromagnetic clutch/gear assembly 74 which when energised drives a gear 75 mounted on a lay shaft 76.

Assembled to the lay shaft 76 is a pulley 77 which via a timing belt 78 drives a pulley 79 mounted on the shaft 80 which drives the input transport roll 56. The nip rollers 49 are driven off the input transport roll 56 through a belt drive 81. The output rolls 61 are driven off the output transport roll 57 through a belt 83.

The shaft 80 has a constant velocity cou pling 82 at the document handler pivot line to allow the drive shaft to split when the document handler is hinged, front to back, for access to the platen while maintaining the correct belt speed regardless of misalignments between the half-shafts.

Two operating modes are provided by the semi-automatic document handler, as follows.

Large Document Copying (LDC) Mode This mode is provided to enable copying of A3 documents onto A3 copy paper.

Before the start of copying the optics 1 2 are parked at the right-hand side of the machine as shown in Fig. 8.

Input documents are loaded, singly, into the document input tray, operating sensor 45.

Operation of this sensor starts the nudger 43, 44 which registers the document against the fixed side and movable end registration edges 47, 48.

A document satisfactorily registered is detected by the input registration (skew) sensors 46 located near the corner provided by the input registration edges. The indicator 69 is illuminated and the nudger 43, 44 is stopped when input registration is achieved.

Failure to satisfy the input registration sensors 46 within 10 seconds causes the nudger to stop and a status code is signalled on the DISPLAY.

Providing the document is correctly registered a 'start print' command enables copying to proceed.

Following 'start print', and a document present at the input, the input nip rolls 49 are closed and then the registration edge 48 is raised. -Following a short time delay process speed drive is applied to both the input nip rolls 49 and the platen belt 52 via the electromechanical clutch 74. The nudger 43, 44 is also restarted.

The document is transported across the exposure slit at process speed. Synchronisation between the document image and the copy paper is achieved by releasing the copy paper from the hold position at the appropriate time. This time is provided by a timer, initiated by the document lead edge arriving at the synchronisation (registration) sensor 53, timing out.

Documents following the first may be copied without start print commands providing these documents are entered within a time out period of 90 seconds.

Entry of documents into the document handler with less than the required interdocument gap is prevented by stopping the nudger and closing the input registration edge 48 as soon as the document trail edge passes the synchronisation sensor 53.

The platen belt 52 and input nip rolls 49 are brought to rest between copies so as to provide a 'standing start'. This prevents documents being skewed which could occur if the input nip rolls are rotating during closure.

Document jams are detected if documents do not reach, or fail to clear, sensors within preset times. The operator is informed of the jam via the machine copy counter which will indicate a fault code.

Jams are cleared by removing all documents from the document handler. Copying is restarted as for a new job.

If the document handler interlock switch is opened a status code is indicated on the machine counter.

Semi-automatic Mode This mode provides for copying documents up to and including B4 size and single or multiple copies of each document. In this mode the first copy of a document is copied in constant velocity mode exactly as an L.D.C.

copy, i.e. by conveying it across the stationary optical system 12.

If additional copies of the same document are selected the document is stopped on the platen. This is achieved by raising the platen registration edge 60 by energising a solenoid and stopping the platen belt 52, following the arrival of the document at the registration edge. The platen belt 52 is stopped for this purpose a timed interval after it was started.

Further copies are provided by scanning the optics 1 2 across the document (Fig. 9).

Following the last copy from a document the optics are driven to the right-hand or L.D.C. position and parked.

If a further document has been placed at the document input this is copied in constant velocity mode whilst the first document is being ejected into the catch tray 41.

If no further document is present at the end of the copy run, the first document is ejected into the catch tray 41.

Apart from the stopping of documents on the platen and scanning, the operation is identical to LDC mode.

Platen Mode Normal operation of the machine is possible without the use of the document handler. To permit the copying of books and thick documents the machine logic does not require the document handler interlock to be closed.

It will be appreciated that while a specific embodiment of the invention has been described, various modifications may be made to the specific details referred to herein without departing from the scope of the invention as defined in the appended claims. For example, although the pre-registration device or nudger 43, 44 is shown as a wheel, which may be a foam wheel, other forms of nudger, such as a paddle wheel, may be utilised. Further, the input nip rolls 49 and registration gate 48 could be operated by separate mechanisms in timed relation.

Claims (4)

1. A document handler in which documents to be copied are corner registered against adjacent side and end registration datum edges prior to being advanced through the document handler, document advancing means being activated in response to the sensing of the presence of a document at the registration corner, characterised in that two sensors, both of which must be satisfied for activation of the document advancing means, are positioned along said datum edges respectively at locations spaced from the corner.

2. A document handler according to claim 1, including a support surface for documents being registered which slopes downwardly towards said end registration edge.

3. A document handler according to claim 1 or 2 including means for urging a document into corner registration.

4. A document handler constructed, arranged and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.