DEVICE FOR CHANGING THE POSITION OF SHEETS OF PAPER IN A FLOW AS WELL AS EQUIPMENT FOR LATER HANDLING OF THE SHEETS

The present invention relates to a device for changing the position of sheets of paper in a flow of sheets.

The printing or printer unit of printing machines or copiers is normally followed by an equipment for later handling of printed sheets, such as collection, sorting, stapling and folding of the sheets for the provision of booklets as well as transportation and delivery of sheets or booklets, or piles of sheets or booklets, in a desired way. Such post-processing equipment has to be constructed to handle an often fast flow of printed sheets. Normally, the sheets have to be post-processed at substantially the same rate as the one at which they are fed out from the printing machine or copier. If this is not possible, the time interval between the sheets has to be increased. In SE 525 481 , a way is disclosed to provide a sheet buffer by the fact that sheets of a flow are buckled and are kept buckled until a suitable moment for output by controlling rollers for feeding the sheets.

In such a post-processing equipment, there is also often a need for change or correction of the position of incoming sheets. Thus, sheets may be fed into the equipment with an erroneous location, e.g., obliquely in relation to the feeding direction through the equipment. Sheets may, e.g., be fed in from the printing or printer unit centre registered, while from the post-processing equipment, it is wanted to have edge-registered piles, or vice versa, or sheets fed in may need to be rotated, e.g., 90° for the subsequent stapling and folding operations.

The object of the present invention is to provide such a device for correc- tion or change of the position of sheets of paper in a flow of sheets, which device has the capacity to handle high flows of sheets from printing machines or major copiers.

This object is attained by a device of the type mentioned by way of introduction having the features defined in claim 1. By arranging a plurality of cassettes, in which the position change is carried out, in parallel in the sheet-feeding or sheet-flow path, as well as making the cassettes in the way defined in claim 1 , position change of each sheet is effected fast and reliably, which results in that requisite position changes can be made

without stopping the flow of sheets from, e.g., a printer unit, also at high flows of sheets.

According to an advantageous embodiment of the device according to the invention, the side of the plate facing the sheet path has a coating having large friction against paper, preferably a rubber coating. In this way, the plate gets a good grip against the sheet of paper, so that it follows the motion of rotation of the plate in a reliable way. This is of course of greatest importance for the sheet to end up in exactly the desired location.

According to another advantageous embodiment of the device according to the invention, each cassette is displaceable along sliding bars arranged perpendicularly to the sheet-feeding path for translation of sheets laterally in relation to the direction of the sheet-feeding path. Accordingly, in this way, sheets can be moved laterally in order to provide, e.g., a pile of edge-registered sheets from incoming centre-registered sheets, or vice versa. According to yet an advantageous embodiment of the device according to the invention, time-control members are arranged to control the driving motor of the feed rollers for output of sheets from the cassette at predetermined intervals. In this way, sheets that arrive at varying intervals can be fed out from the cassettes at exactly equal intervals. It is also possible to change the intervals between the sheets fed out from the cassettes. In some cases, for the subsequent handling, it may be desirable, e.g., to feed out pairs of sheets from the cassettes at a small interval between the sheets in the pair and at a larger interval between each pair of sheets.

According to an additional advantageous embodiment of the device according to the invention, a flap arrangement is arranged at the entrance side of the cassettes, which flap arrangement is controllable from the sensors at the cassettes in order to direct incoming sheets to an empty cassette. Having a plurality of parallel cassettes, accordingly it is possible, by means of such a flap arrangement serving as a path selector, to all the time direct incoming sheets to an empty cas- sette, which results in a device having very high capacity.

The invention also relates to an equipment for post-processing of sheets from a printing or printer unit of printing machines or copiers comprising a device according to the invention.

In order to explain the invention in more detail, an embodiment example of the device according to the invention will now be described, reference being made to the appended drawings, in which Figure 1 schematically shows an example of post-processing equipment for printing machines and fast copiers, Figures 2 and 3 show the device according to the invention in side view and plan view, respectively, and Figure 4 shows a detail of the device according to the invention on a larger scale.

Figure 1 schematically shows an example of post-processing equipment for printing machines and fast copiers. This equipment comprises upper output trays 1 having output wheels 2 at the exit side. At 3, the inlet to the equipment from a preceding machine, such as a printing machine or copier, is shown. The equipment in Figure 1 comprises a device according to the invention having three cassettes 8. From the exit of this device, the flow of sheets is directed via a flap 6 either to a conveyor 10 for delivery of the sheets, or via an additional flap 7 to an outlet 4 for possible transfer to a subsequent machine.

By means of the conveyor 10, the sheets are brought to a subsequent collection station 13. From this collection station 13, the sheets 14 are brought to a delivery table 15 in a stapling station having a stapling apparatus 11 for stapling together sheets into booklets. From there, stapled sheets 16 are brought to a main table 17 for delivery.

In Figure 1 , furthermore, grippers 9 of the conveyor 10 to hold sheets during the transportation are schematically shown. Numerals 12, 18, 19, 20, 21 and 22 designate different components belonging to the collection and stapling stations. The device according to the invention for change of the position of sheets of paper in a flow of sheets is framed by the dashed line A in Figure 1 and is shown in more detail in Figures 2-4.

In Figure 2, an embodiment example of the device according to the invention is shown having three cassettes 47, arranged in parallel in the sheet-flow path. On the entrance side of the cassettes 47, a flap arrangement 5 is arranged. Said flap arrangement 5 is controlled from, preferably optical, sensors 41 in the cassettes 47 in order to direct each incoming sheet to an empty cassette 47. Incoming sheets are driven into the cassettes 47 by feed rollers 42 attached to motor-driven spindles 49. The feed rollers 42 are arranged in pairs and spring-

biased against each other, see Figure 4. When the sheet has reached the interior of the cassette 47, the feed is stopped.

At the entrance of each cassette, there are optical sensors 41 that detect the leading edge of the sheet and thereby the location of the sheet in the direction of the sheet-feeding path, laterally in relation to the direction of the sheet-feeding path, as well as the rotary position of the sheet.

For the rotation of the sheet in the cassette 47, a mechanism controlled by the sensors is arranged. Said mechanism comprises a plate 43 carried on one side of the sheet path and an opposite disc 44 rotatably mounted in ball bearings 48 and arranged at the other side of the sheet-feeding path, see particularly Figure 4. The plate 43 is spring-biased in the direction from the plane of the sheet-feeding path, see 51 in Figure 4.

The disc 44 lies on a level with the underside of the sheet-feeding path with the outer edge folded from the path so that sheets slide over the disc 44 with- out getting caught.

The motors driving the spindles 49 of the feed rollers 42 are reversable. Via ratchet bearings, the rotary spindles 49 are coupled to a swinging arm 50 being in connection with the plate 43 in order to, upon reversal of the driving motor, bring the plate 43 against the opposite, rotatably mounted disc 44 while overcoming the spring-bias from the springs 51. In doing so, the sheet in the cassette 47 is squeezed-in between the plate 43 and the opposite disc 44.

The feed rollers 42 are also coupled to the ratchet, so that upon further reversal of the driving motor, the feed rollers 42 in each pair of feed rollers 42 will be separated, likewise while overcoming the spring-bias. The sheet is now free to be rotated inside the cassette.

A torque motor 40, preferably a stepping motor, then rotates the plate 43, and thereby the squeezed-in sheet, into a predetermined desired location. Next, the motor driving the spindles 49 of the feed rollers 42 releases the feed rollers 42 so that the same move against each other in each pair of feed rollers as a conse- quence of the spring-bias. Thereby, the feed rollers 42 grip the intermediate sheet again, the rotary position of which now has been corrected. Simultaneously, the plate 43 is released so that it, as a consequence of the spring-bias thereof, moves from the opposite disc 44 and accordingly loosens the engagement thereof with the sheet.

For correction of the position of the sheets laterally, the cassettes 47 are displaceable along sliding bars 46 arranged in a frame 45 and perpendicularly to the direction of the sheet-feeding path, see Figure 3. This lateral displacement is also motor-driven and controlled by the sensors 41 , which detect the position of the sheet at the entrance into the cassette 47.

Time-control members (not shown in the drawings) are also arranged to control the driving of the feed rollers 42 in order to, if required, delay the sheet feeding, so that the sheets are fed out from the cassettes 47 at predetermined intervals, which may differ from the intervals between the sheets at the entrance into the cassettes 47. In the equipment illustrated in Figure 1 , it is, e.g., necessary to synchronize the output of sheets from the cassettes 47 with the motion of the grippers 9 of the following conveyor, which will grip the sheets fed out. This is accomplished by controlling the sheet output from the cassettes 47.

Thus, by the device according to the invention, it is possible, upon fast flows of sheets, to correct and change the positions of the sheets in the direction of the sheet-feeding path as well as laterally in relation to the same feeding direction, as well as also the rotary positions of the sheets.

After the positions of the sheets have been corrected in the requisite way, such as has been described above, the driving of the feed rollers is started again and the sheets are fed out from the device for possible further handling.