WO2000056643A1

WO2000056643A1 - Method and device for aligning individual sheets in a sheet processing machine

Info

Publication number: WO2000056643A1
Application number: PCT/EP2000/002374
Authority: WO
Inventors: Markus Stahuber
Original assignee: Oce Printing Systems Gmbh
Priority date: 1999-03-18
Filing date: 2000-03-17
Publication date: 2000-09-28
Also published as: EP1161394A1; EP1161394B1; DE50004422D1

Abstract

The invention relates to a device for aligning a sheet-type recording medium (2) in a sheet processing machine (11). Said device is provided with a conveyor path (6) across which said recording medium (2) is transported from an input position (at 3a) to an output position (at 3b) in a direction of conveyance (A). A stop (1) is provided towards which the recording medium (2) is moved during conveyance in a transversal direction to the direction of conveyance (A) in order to align said recording medium. The device also encompasses a conveyor device (4, 5, 9) which moves the part (26a) of the stop-facing edge (26) of the recording medium (2) that is in the rear position with regard to the direction of conveyance towards the stop (1) before moving its front part (26b) towards the stop.

Description

Method and device for aligning single sheets in a sheet processing device

The invention relates to a method and a device for aligning single sheets in a sheet processing device.

In printing or copying machines, it is usually necessary to record laterally for scanning or printing, i.e. to be aligned transversely to a transport direction on a reference edge. This is particularly necessary when interference affects the record carrier and deflects it from a target transport path. Such interference can arise, for example, from tolerance-sensitive recording media, for example if the format of a sheet-shaped recording media varies. The stability of the transport track is particularly at risk if the record carriers are to be transported over relatively long transport distances, e.g. when a sheet-shaped record carrier has to be transported over a multiple of its length.

If the record carrier is outside the target transport path specified in the device, it cannot be processed without errors. In a printing device, for example, this leads to an oblique print image on the recording medium.

An alignment device for a single sheet printing device or a copying machine is known for example from O-98/18053 AI. knows. In this alignment device, a sensor is provided which detects the lateral edge of the recording medium, determines its position relative to a desired pressure position and shifts a transport device transversely to the transport direction of the sheet depending on the deviation of the actual position from the desired position of the sheet. Although this device permits highly precise positioning of the recording medium, it is relatively complex because of its sensor device and the movable transport device.

A somewhat simpler alignment device is known from DE 27 50 252 AI. In this device, a sheet-shaped original is required for alignment with a stop. The original is driven by a roller arrangement on which balls rest, the original being passed between the rollers and the ball.

Devices are also known from US Pat. No. 4,179,117 A and US Pat. No. 5,031,895 with which sheet-shaped recording media can be aligned on an edge lying transversely to the transport direction of the recording media.

In the case of unstable recording media, for example in the case of light-weight paper sheets with 60 g / m ² , damage to edges or corners can occur during the alignment process in mechanically acting alignment devices.

Arrangements are known from DE-C-922171, from US-A-3, 980, 296 and from JP-A-63-127955 with which individual sheets of paper can be aligned on a lateral guide edge in a transport channel .

It is an object of the invention to provide a method and an apparatus for feeding sheet-shaped recording media in a sheet processing device, during which Damage to edges or corners can be largely avoided, even with sensitive recording media.

This object is achieved by the invention specified in the independent claims. Advantageous embodiments of the invention are the subject of the dependent claims.

The invention is based on the knowledge that a particularly gentle alignment, which is also suitable for sensitive recording media, is possible in sheet feed devices, in that the part of the recording edge on the stop side at the back in the transport direction first moves to a stop, i.e. is applied to a reference edge, and in the further course the remaining parts of the edge of the recording medium to be aligned are guided to the stop. This can be done in an alignment section in particular by rotating the recording medium with the rear part of its stop-side edge toward the reference edge (stop). It is only in the further course of the alignment process that the recording medium is then placed completely against the reference edge, thus achieving a material-friendly alignment of the recording medium even with lightweight recording media. In particular, the edge of the recording medium located at the front on the aligning stop in the transport direction is protected. By a suitable choice of the transport device in the alignment section, e.g. by means of a driven roller on which a ball rests and by arranging the transport device near the stop, it is avoided that less rigid recording media form folds or bumps on the stop.

The sheet-shaped recording material is aligned on the stop, in particular at a constant transport speed, without additional acceleration devices. The stop forms a reference edge, which in particular corresponds to the longitudinal edge of a target transport path. The alignment therefore takes place continuously over the entire alignment route. In order to adapt the transport speed in the alignment section on the input or output side to the transport speeds of adjacent devices or modules, the recording medium can be decelerated or accelerated at the beginning or at the end of the alignment section. In this way, in particular relatively short sheet spacings in the sheet stream of successive record carriers can be achieved. For this purpose, it is advantageous to provide a freewheel on the input-side and / or on the output-side drive roller or even on all drive rollers of the alignment section.

The device according to the invention comprises in particular at least one drive roller, the drive axis of which is at an acute angle to the transport direction. This drive roller can interact with a ball, which presses the recording medium passing by against the drive roller and thus generates the friction required for transport. The size, material, surface structure and weight of the ball can be easily adapted to the respective requirements. The ball can only generate the friction through its own weight. It can be freely stored in a ball cage. On the other hand, the ball can be provided with a pressure spring acting in the direction of the recording medium to support the frictional force acting on the recording medium, in particular when relatively heavy recording media are to be processed.

The provision of ball / roller pairs in the alignment and transport device according to the invention achieves particularly gentle processing of the recording media, as a result of which very light sheets of 60 g / m ² or less can be aligned gently and safely. The structure according to the invention also provides a simple, inexpensive and space-saving device which is only slightly susceptible to faults and has a wide range of usable formats, materials, types and weights for the sheet-shaped recording media, without having to make settings (parameter changes) for processing the various recording media the alignment section or on the transport or alignment device.

In order to make particularly serious changes to the recording material to be processed (e.g. cards, labels, foils, etc.) and / or to make significant changes to the formats, weights and the like to be processed. The like. To be able to accept it is possible to adapt the roller size, friction material and / or angular arrangement and the corresponding parameters of the balls on the alignment and transport device. It is just as possible to make the number and arrangement of the roller / ball pairs.

The ball of a roller / pair of balls is in particular held in a free-running manner in a ball cage and, by means of its gravity, is centered on the transport roller which is inclined to the transport direction. The arrangement consists of several pairs of rollers / balls, in particular three such pairs.

Exemplary embodiments of the invention are explained in more detail below with the aid of some figures. Show it :

1 shows a printing device, FIG. 2 shows an alignment section,

3 shows the alignment section in supervision, FIG. 4 shows the alignment section in view and FIG. 5 shows a stop of the alignment section.

1 shows a printing device 11 which conveys sheet-like recording material, here individual paper sheets, from input compartments 13 via a feed channel 14 to a printing station 12. The printing station 12 works according to the electrophotographic principle, the printing processes being controlled by a device controller 20. The printed individual sheets are then passed through a fixing station 17, in which the toner image which has been overprinted in the printing station 12 is fixed on the paper sheet. The paper sheets printed in this way are fed via an output path 18 to paper output compartments 19 or a paper output interface 19a for further processing in other devices. For this purpose, the device controller 20 is connected to all electronic components of the printing device, for example to the fixing station 17 and to the drive 21. The paper sheets are to be aligned in particular in front of the printing station 12 in the feed channel 14, so that the printed image can be printed on the paper in a precise position. Depending on the application, such an alignment can also be carried out in the output path 18 or in the area of the output interface 19a in order to feed the sheets correctly aligned to further devices.

In addition to the input compartments 13, the printing device 11 is connected to an external paper supply module 15, which is connected via a connecting channel 16 into the input area 13 of the printing can supply device 11 at an interface 24. For this purpose, a tunnel-shaped connecting channel 16 with a corresponding drive 22 is provided. The controller 20 of the printing device 11 is also connected to the drive 22 and to a controller 23 of the external supply module 15.

Further details of the paper supply modules 13 and 15 and the connecting channel 16 are described in WO-Al-98/17572, the content of which is hereby incorporated by reference into the present description. As can be seen from this WO publication, the external supply module 15 (provided with reference number 2 there) can be connected to further paper supply modules (provided with reference number 2 ^{λ there} ) via the interface 25. For this purpose, connection tunnels are again provided, which can either be designed in exactly the same way as the connection channel 16 (with a lateral orientation) or as a simple transport module without a lateral paper orientation.

In order to transfer individual sheets from the supply module 15 laterally aligned to the interface 24 of the printing device 11, an alignment of the lateral edge of the sheet takes place in the connecting channel 16, which is explained in more detail with reference to FIG. 2. Sheets of paper 2 come from the supply module 15 into the connecting channel 16 at a speed v ₀ on a pair of transport rollers 3a into the connecting channel 16. They have a lateral offset S with respect to a desired transport position or reference edge 8. The front transport roller pair 3a of an alignment section transports the paper sheets onto a running surface 6 in the transport channel 16 until the front edge of the sheet reaches the area of a next transport device, namely a driven roller 5, on which a ball 4 rests. The ball 4 is freely supported in a ball cage 7 and only lies on the drive roller 5 with its own weight. The roller 5 is a Drive axis 9 driven at an angular velocity ω. Three such identical roller pairs 4, 5 are provided within the transport channel 16 or the alignment section. The drive axis 9 is in each case at an acute angle α to the perpendicular to the transport direction A. As soon as the paper sheet 2 is gripped by the first ball-and-roller arrangement, the inclined roller 5 transports the sheet in an inclination at the angle α to the main transport direction A. Direction of transport at speed v _a .

The paper sheet 2 gripped by the pair of ball rollers 4, 5 is pushed at a speed v _a at an acute angle α to the transport direction A against the lateral stop 1 and thus against the reference edge 8 and thereby aligned within the paper channel 16. The following applies: v _a = ω • r _w , where r _w denotes the radius of the transport roller 5.

The inclined roller 5 or the ball 4 engages the paper sheet 2 in the edge region of the sheet 2 on the side of the reference edge 8 or the stop 1. If the paper sheet 2 rests on the stop 1, the roller 5 causes movement in the following only one sheet movement parallel to the transport direction A along the stop 1 with the speed v _r . This movement is influenced by the components of the static and sliding friction of the inclined friction roller 5 acting on the paper sheet as well as by the weight force Fg of the exposed ball 4 acting on the paper sheet as well as by the peripheral speed of the roller 5 with its component v _a • cos α . As a result, the paper sheet is moved in two directions at different speeds. The resulting speed v _r can be varied by varying the speed of the inclined roller 5, for example via a gear ratio or a controllable stepper motor of the general transport speed v _{0 of} the ^' pressure device 11 can be adapted.

The engagement of the obliquely arranged pairs of rollers / balls in the alignment section between the two pairs of rollers 3a and 3b takes place in the edge region of the paper sheet 2 on the side of the reference edge 8 or the stop 1. The pair of balls and rollers 4, 5 engages in each case on the incoming side of the paper sheet in the area of the corner near the stop. The engagement of the rollers / pairs of balls 4.5 thus takes place asymmetrically, i.e. outside the middle of the sheet on the stroke-side sheet half. This asymmetrical engagement, on the one hand, and the friction between the underside of the sheet and the running surface 6, which acts uniformly on the entire paper sheet 2, causes the sheet to rotate to the stop 1 in such a way that the rear part 26a of the sheet edge 26 near the stop first strikes the stop 1. Only in the further course of movement do the other parts and, at the end, the front part 26b of the sheet edge 26 lie gently against the stop 1, neither the sheet edge 26 nor sheet corners being damaged and other sheet parts also remaining intact, in particular not being kinked. In the further course of the movement, the sheet 2 is transferred to the ball / roller pairs 4, 5 following the first pair until the sheet finally reaches the transport roller pair 3b on the output side. This pair of transport rollers 3b then takes over the further transport at the standard speed vn of the printing device 11.

Due to the movement sequence described above, the paper sheet is rotated towards the stop during the alignment process. The pivot point depends on the friction surface of the paper sheet. This is in turn determined by the coefficient of friction between the paper sheet (record carrier 2) and the running surface 6. The engagement of the roller-ball pairs 4, 5 in the marginal area of the paper sheet 2 and the frictional forces acting on the paper sheet 2 initially cause the paper sheet to rotate with its rear edge 26a toward the stop 1 or towards the reference edge 8. In the further course, the paper sheet 2 is then completely applied to the reference edge 8. The free mounting of the ball 4 in a ball cage 7 has the effect that an essentially asymmetrical, ie no preferred direction of friction force acts on the recording medium. The ball 4 thus does not horizontally determine the direction on the recording medium, in contrast to the roller 5, which specifies a clear preferred direction. Within the pair of balls and rollers 4, 5, only the roller 5 effects frictional guidance, but not the ball 4.

FIG. 3 shows further details of the parts relevant for the function of the alignment device. The centers of the balls 4 and the rollers 5 are at a distance b from the stop 1. This distance is considerably smaller than the sheet length transverse to the main transport direction A. This prevents longitudinal folds or bumps from occurring in the paper sheet 2 in the course of the alignment process.

The length of the alignment path is to be dimensioned as a function of the paper sizes to be processed, the maximum offset S to be corrected and the angle α present. To ensure trouble-free operation for the broadest possible range of record carriers (types: paper, foils, labels; surfaces: rough, fine, coated; format: A4, A4, letter; weights: 40 g to approx. 300 g) - Most, the number, positions and dimensions of the rollers 5 are

Balls 4 and their surfaces and weights and the angle α to adjust. For a high-performance printing device with a printing capacity of up to 160 pages per minute, it has proven to be advantageous to use the combination of 3 balls / roller pairs 4, 5 shown in the figures in an alignment path, the distances between two rollers 5 or two balls 4 are smaller than the smallest paper size to be processed. Sanded glass balls with a ball weight of 40 g, which run freely in a ball cage and press centrically on the rollers by gravity, have a reliable paper spectrum of 60 g / m ² to

200g / m ² result. In addition to glass spheres, V2A steel spheres or plastic spheres or spheres made of other materials suitable for spherical production that do not leave any stains due to abrasion on the recording medium are also suitable.

The rollers 5 are arranged at an acute angle to the transport direction A in an angular range of 0> α <40 °, preferably in the angular range between 5 ° and 15 °. The roller surface has high friction relative to the medium (paper) to be transported. Suitable roller surfaces for paper are e.g. Elastomer surfaces.

Microcellular polyurethane foams with cell sizes between 120 and 160 μm and with a coefficient of friction compared to paper are particularly suitable for the present arrangement of an alignment and transport device in which the roller surfaces interact with the above-described ground balls made of V2A steel or Gals 1.2 and 2.0 especially between 1.5 and 1.7. The Shore hardness (A) of the polyurethane foam should be between 25 and 50, in particular between 30 and 45 or exactly 38.

While in the embodiment shown in FIG. 4 the roller surfaces are flush with the running surface 6 ß, these surfaces can protrude about 0.5 to 3 mm above the transport plate 6 in other embodiments. The transport plate 6 has a corrugated or embossed surface and is provided, for example, from a 0.8 mm thick steel plate with an embossing depth of 1.2 mm. These depressions, which are provided at short intervals, ensure sufficient friction between the paper and the transport plate 6 and yet avoid excessive adhesion or static charging of the paper.

The balls 4 are stored in a ball cage 7, for example with some play in a hollow cylinder. The ball cage 7 holds the ball 4 horizontally centered on the corresponding, driven roller 5. The bow 4 can be prevented from falling out by a clip closure or a jacket taper when the entire arrangement is tilted or transported.

If the printing device is operated with record carriers of very different formats and / or weights, then different transport speeds v _r can arise due to the different frictional forces within the alignment path. This can lead to a change in the gap between the sheets in the paper flow. In order to again produce constant blade spacing after the side alignment or behind the alignment section, the pair of rollers 3b can be accelerated in a ramp-controlled manner at the end of the alignment section. For this purpose, the speed v _{a is} selected to be lower than the process speed Vo within the alignment path. Furthermore, at least the roller 5 arranged on the output-side pair of transport rollers 3b is provided with a freewheel bearing 10 (see FIG. 4). This freewheel bearing 10 engages the drive axle 9 with the drive roller 5 when the drive roller 9 moves in the transport direction, but releases it when the drive roller 9 axis 9 stands or the drive roller 5 rotates faster than the drive roller 9 due to the faster movement of the output-side transport roller pair 3b. The sheet lying between the drive rollers 3b and the output-side ball-roller pair 5 can thus be freely accelerated within the alignment path.

The freewheel bearing has a freewheel in the transport direction and locks against the transport direction. If the pair of balls and rollers on the input side also has such a freewheel, the paper sheet can be picked up non-destructively if it runs into the alignment path at a higher input speed (v ₀ > v _r ).

In Figure 5, the transport plate 6 and the stop 1 is shown in a sectional view. They are connected to each other to form a V-shaped receptacle 27, so that the paper sheet 2 is securely received. For this purpose, the stop 1 has a leg 28 which runs obliquely upwards, the transport plate 6 has the embossed depressions 29.

The invention has been described using the example of a printing device. It is clear that the invention can also be used for alignment sections on other devices for processing sheets or documents. It does not matter whether just one sheet is aligned or a document that spans several sheets, such as a brochure or an envelope. The invention can thus be used in printing devices, copying machines, original scanners or also in other devices for processing documents, for example in enveloping systems, in collators, in document feeders or document discharge devices. Reference list

1 stop

2 recording media (paper sheet) 3a front pair of rollers

3b rear pair of rollers

4 bullet

5 drive roller

6 tread 7 ball cage

8 reference edge

9 drive axle

10 freewheel

11 printing device 12 printing station

13 input compartments

14 feed channel

15 External storage module

16 connecting channel (tunnel) 17 fixing station

18 output path

19 paper output trays 19a output interface

20 Device control 21 Drive in the pressure unit

22 Drive in the tunnel

23 Control of the storage module

24 input interface

25 Supply interface 26 Sheet edge close to the stop

26a rear part of the edge 26

26b front part of the edge 26

27 recording

28 legs 29 recesses of the transport plate (= running surface) A = main transport direction b = distance between stop and roller / ball engagement point

S = transport offset (at infeed) v ₀ = speed of the roller pairs v _a = speed of the rollers / roller arrangement v _r = speed component in the direction of transport

Claims

Claims:

1. A method for aligning a sheet-shaped recording medium (2) in a sheet processing device (11), wherein

(a) the recording medium (2) is transported from an input position (at 3a) via an alignment path (6) in a transport direction (A) to an output position (at 3b),

(b) the record carrier (2) during the transport movement transversely to the transport direction (A) to a stop

(1) with which it is aligned, is moved,

(c) the part (26a) of the stop-side edge (26) of the recording medium (2) located at the rear in the transport direction (A) is moved against the stop (1) in front of the front part (26b) thereof,

(D) the transport in the transport direction (A) by means of several, along the transport direction (A) arranged, driven rollers (5), each one for

Have transport direction (A) at an acute angle (α) inclined axis of rotation (9) and

(d) the recording material (2) on the rollers (5) is pressed against the roller (5) by the weight of a ball (4) interacting with the roller (5), causing a friction between roller (5) and recording medium ( 2) arises.

2. The method of claim 1, wherein over the alignment

(6) two independent devices (11, 15), in particular a recording medium supply module (15) with one Pressure device (11), are connected to each other.

3. The method according to any one of the preceding claims, wherein the rollers (5) are each driven at a constant speed.

4. The method according to any one of the preceding claims, wherein during the alignment the transport speed in the transport direction (A) is constant.

5. The method according to any one of the preceding claims, wherein the transport speed in the transport direction (A), in particular after the alignment, is changed, whereby at the end (at 3b) of the alignment section a constant sheet spacing of successive sheets (2) is generated.

6. Device for aligning a sheet-shaped recording medium (2) in a sheet processing device (11), in particular for carrying out a method according to one of the preceding claims, with

(a) an alignment path (6) via which the record carrier (2) is transported from an input position (at 3a) in a transport direction (A) to an output position (at 3b),

(b) a stop (1) to which the recording medium (2) is moved during the transport movement transversely to the transport direction (A) for alignment, wherein

(c) a transport device (4, 5, 9) is provided, by means of which the part (26a) of the stop-side edge (26) of the recording medium (26) located at the rear in the transport direction (A) temporally before its front part (26b) is moved to the stop (1).

7. The device according to claim 6, wherein the transport device (4, 5, 9) comprises at least one drive roller (5) whose drive axis (9) is at an acute angle (α) to the transport direction (A).

8. The device according to claim 7, wherein the drive roller (5) has a surface provided with a friction layer, wherein the friction layer consists of a polyurethane material and has a coefficient of friction between 1 and 2.

9. Apparatus according to claim 7 or 8, wherein each drive roller (5) is associated with a ball (4) which is freely supported in a ball cage (7) and which, in particular, only by its own weight prevents the recording medium (2) from passing against the drive roller (5 ) presses, which creates a friction between the drive roller (5) and the recording medium (2).

10. Device according to one of claims 7 to 9, wherein the drive roller is connected via a freewheel (10) to the drive axis (9) through which the recording medium (2) is freely movable in the transport direction (A).

11. Device according to one of claims 7 to 11, wherein a plurality of driven ball-roller pairs (4,5) are provided, which are each arranged so that the smallest, processable in the device format of the recording medium (2) with at least one ball -The pair of rollers (4, 5) is engaged.

12. Printer or copier with an alignment device according to one of claims 7 to 11, wherein the alignment device Direction between a sheet input station (at 3a) and a printing station (12) is arranged.

13. Scanning device with an alignment device according to one of claims 7 to 12, wherein the alignment device is arranged between a document input station and a scanning device.