The invention relates to device for stacking and stapling sheets, said device comprising

- a stacking area into which individual sheets can be fed in one feeding direction ,

- a stack abutment which is movable from a releasing position into an abutment position, in which it limits the stacking area, and back again and on which the sheets fed to the stacking area can be stacked when it is in its abutment position, and

- a stapling device which is arranged in a housing which laterally sur¬ rounds the stacking area from above and below.

Devices of this type are suitable, for example, in connection with equip¬ ment used for the handling of copies fed into a copier in order to stack copies produced in the copier and stapling the stacks thus obtained before their further transport.

A device of this type is known from DE-OS 21 44 248. This known device has one single stapling device only which is arranged at one side of the stack .

Since it is desirable that a stack should be stapled along one side by two staples which are located adjacent to the ends of said side, it is known from EP 147 142 for one stapling device each to be provided at either side of the stacking area, with the housings of said stapling devices being movable and adjustable vertically to the direction in which the sheets are fed into the stacking area. However, this known device does not have an uninterrupted stacking area. The sheets introduced into the stacking area have to be moved out of the stacking area, in a direction opposite to the feeding direction, after they have been stapled to form a stack. Moreover, each housing in this known device is movable by a drive of its own which is controllable by a complicated control unit in a timed relationship with a drive of the other housing.

In connection with the device referred to at the beginning, the invention provides a) that a housing each with a stapling device is arranged at either side of the stacking area, b) that both housings are movable and adjustable vertically to the feeding direction, and c) that a common drive is provided for a simultaneous movement of both housings in opposite directions.

This results in a device with an uninterrupted stacking area wherein the feeding direction of the sheets fed to the stacking area and removed from said area need not be changed.

Thanks to feature c) only one drive has to be moved for effecting a move¬ ment of the two housings , by which the stapling devices are adapted to different sizes of the stacked sheets so that a considerably simplified con¬ trol is obtained.

In the case of an advantageous embodiment of the invention the drive has a spindle which has two oppositely directed threads which are held in engagement with cam portions on the housings. As a result, a particularly simple drive is obtained for the simultaneous movement of the two housings in opposite directions .

According to another advantageous embodiment a stack abutment is pro¬ vided in each housing. This results in that when the stapling device is adjusted to specific sheet sizes, the position of the stacking abutments is also_ simultaneously adjusted to said sheet size,

The invention is explained in further detail in the following description of two embodiments illustrated in the drawings wherein:

Fig. 1 shows a perspective view of a first embodiment of a device for stacking and stapling sheets;

Fig. 2 shows a view of a mounting plate forming a side wall of a hous¬ ing of a stapling device along with the drive for the stapling device and the stacking abutment;

Fig. 3 shows an end view of a housing for a stapling device according to a second embodiment.

The sheet stacking and stapling device is arranged in a machine housing 11 which has a stacking surface 12 with a slight downward inclination, which defines the lower side of a stacking area. For guiding the sheets , which are fed to the stacking area from the upper edge of the stacking surface 12, as shown in Fig. 1 , in a feeding direction 13 vertical to said edge, lateral guide means not shown in the drawing are provided which can be adjusted to the different sizes of the sheets fed. Apart from said surface the stacking area is not defined so that the sheets fed individually into the stacking area in the feeding direction 13 can be removed in the form of a stack after having been stacked in the same feeding direction 13. For stacking the sheets fed to the stacking area, two stack abutments 14 are provided which, when in their stacking position shown in Fig. 1 , define the stacking area at the lower side and which can be moved from said stacking position into a release position in which they clear the path so that the stacks can be removed.

Two stapling devices 15 each of which is arranged in a housing 16 are provided for stapling the sheets stacked in the stacking area. Each of the two housings is movable vertically to the feeding direction 13 and adjust¬ able in various positions.

A spindle 17 with two oppositely directed threads 18 at either side of its center, which are held in engagement with cam portions in the form of eyebolts 19 having internal threads , serves as a drive for moving the two housings 16. On each of the two housings 16, an eyebolt 19 is arranged so that when spindle 17 is rotated the housings 16 are moved by equal dis¬ tances in opposite directions vertically to the feeding direction 13. In order to keep the stapling devices 15 arranged in the housings 16 in their positions vertical to the stacking surface 12 as required for stapling, the

housings 16, connected at their upper ends with spindle 17, are guided at their lower ends by a guide rail 21 which extends parallely with spindle 17 and is located below the stacking surface 12. The stacking surface 12 is formed by an inclined plate 22 which terminates at its lower end in front of the housings 16 so that said housings can extend to a position below the stacking surface 12. The housings are provided at their lower ends with guide means in the form of shoes 23 which surround the guide rail 21.

For laterally surrounding the stacking area, the housings 16 have recesses 24 whose lower sides 25 are flush with the surface of plate 22 and thus define the lower edge of the stacking surface 12.

In order that the two housings 16 can be guided without jamming, a second guide rail 26 is provided which extends parallely with spindle 17 and is held in engagement with guide means in the form of three rollers 27 mounted on the front side of the housings as seen in Fig. 1.

The side walls of each housing 16 are formed by mounting plates 28 of which the plate forming the front wall is visible in Fig. 1 and the plate forming the rear wall is visible in Fig. 2.

Both mounting plates have recesses 29 on their sides facing the stacking area, said openings being arranged such that the two recesses 29 of the mounting plates of each housing coincide and thus form the housing recess 24. Between the two mounting plates, the stapling device 15 illustrated in Fig. 2 as a whole is arranged above and below housing recess 24. Since various types of stapling devices are known and any of such known stap¬ ling devices can be used in this case, the stapling device as such is not described and illustrated in detail.

To operate stapling device 15 , a disc 31 serves as a drive, said disc having a cam groove 32 and a cam disc 33. A lever 35 pivotable about a journal 34 comprises a roller 36 which engages cam groove 32. Lever 35 engages the stapling device 15 through a slot. When disc 31 is rotated lever 35 is moved up and down and operates- the .stapling device 15 in a

known manner. Between the two mounting plates 28 , a further two -arm lever 37 is mounted for pivotal movement about a journal 38. The upper end of one arm, as seen in Fig. 2, comprises a roller 39 which is urged by a spring 41 into contact with the circumferential surface of the cam disc 33. With its lower end 57, lever 32 operates deflecting elements 61 in a manner usual in stapling devices to bend the stapling wire. The cam groove 32 and the cam disc 33 are arranged in a relation to each other such that when disc 31 is rotated lever 35 is moved first and lever 37 after it. Via another lever 62, which is pivotable about journal 38 and movable by means of an electromagnet 63 , the stack abutment 14 is actuate .

Spindle 17 is driven by means of a motor 42 controllable by a control unit not illustrated in the drawings , the pinion 43 of said motor meshing with a gear wheel 44 connected with the spindle 17. When the sheet size to be stacked is input into the central control unit, motor 42 is moved such that the two housings are moved into the positions matching the size concerned.

In a modified embodiment shown in Fig. 3 , a supporting plate 67 screwed with the mounting plate 28 of the housing is provided on which the eyebolt 19 having the internal thread, the guide rollers 27 and the guide shoes 23 are arranged. As a result of the engagement and guide means for the housing 16 being provided on a supporting plate 67 separate from said housing and being mounted to said housing 16 by means of screws 68, no readjustment is necessary when a housing 16 is exchanged. The housing 16 concerned is just screwed off supporting plate 67 which is not removed - Since supporting plate 67 need not be readjusted, the freshly included housing 16 is automatically adjusted in its correct position after it has been screwed to the supporting plate 67. The supporting plate 67 is shaped such that it does not cover the recess 24 of housing 16.

The above description and the drawings are not confined to the features which are essential to illustrate the invention. Features not disclosed in the description and in the drawings and not mentioned in the claims if necessary also serve to further define the subject matter of the invention _