FR2751315A1 - Manipulating paper sheets for printing on either side - Google Patents

Abstract

The sheet for printing or scanning (99) enters rollers (64A,64B) which drive it past a guide to a second pair of rollers which in turn pick up the leading edge. The first pair of rollers rotate at a higher speed than the second pair and causes slack in the sheet (59). The slack allows the second pair of rollers to revolve as a unit directing the leading edge of the sheet back to the first set of rollers. When the trailing edge of the sheet has left the first set of rollers, they reverse to pick up the approaching leading edge and cause reverse side processing.

Description

 The present invention relates to a device and a method for handling sheets compactly and at high speed.

 The invention applies in particular to printing information or reading information, for example for a scanner, a copier or a fax machine, on each of the two faces of sheets. However, the invention more generally applies to any field in which it is useful to treat the two faces of sheets.

 The word "sheet" includes any sheet-shaped object, thin or thick, consisting for example of plastic, metal, paper, textile, woven or not, leather, building materials, composite materials. It should be noted in this connection that in the sense of the present invention, the length is not necessarily the largest dimension of a rectangular sheet: it is the dimension according to the direction of movement (for example for a roller or for a continuous production not yet cut), and, in the case of sheets, the distance between the leading edge and the trailing edge.

 The word "treatment" is to be considered in a very general sense.

In particular but not exclusively, the word treatment includes here:
reading or analyzing information written on sheets;
forming images or graphics on sheets, for example by printing.

 Document US-A-5,181,714 (SHARP) proposes a device for loading a document at high speed in order to read the information carried on their two faces. This device includes a document transfer and guiding path passing directly above a reading unit. This transfer path comprises a portion substantially in the form of a closed loop for turning over said document. The document, moved by the rotation of successive rollers, makes two passes in front of the reading unit, the document having been turned over in the curved part of the transfer path, between these two passes. This device also comprises means for moving the axis of the loop intended to vary the length of the transfer path as a function of the length of the document processed, in order to reduce the time required to convey said document, this making it possible to increase the speed of processing documents without increasing the speed of the means of transport.

This device has many drawbacks:
the transfer path is certainly reduced, but remains relatively important and winding;
to carry out a treatment on the opposite face of the sheet, the inversion is carried out in a curved part of the path whose curvature is fixed. The maximum stiffness of the sheets that can be treated depends on this curvature;
the curved part of the path risks deforming the processed document by permanently bending the sheet, while it is desired to obtain a flat sheet at the outlet of the device;
the means described for changing the length of the transfer path as a function of the length of the document are complex: they require numerous mechanical and electronic parts, as well as a control system itself complex;
the device described does not make it possible to minimize the conveying time for documents of length less than the minimum length of the turning loop.

 Document US-A-5,201,517 (XEROX) proposes a device for distributing sheets in different directions by using a large roller on which the sheet is wound and a small roller which clamps the sheet against the large roller and whose l he axis rotates around the axis of the large roller, driving the pinched sheet. Depending on the position taken by the small roller during its rotation around the axis of the large roller, the joint rotation of the two rollers allows the sheet to be sent in different directions. This device is capable of returning the sheet to a processing means after it has been turned over by the dispensing device, thereby allowing double-sided processing of the sheet.

This device also has many drawbacks:
- the transfer path is long and winding;
- the dimensions of the large roll are necessarily large so that the sheet can be wound on its surface. Its dimensions are all the more important the more rigid the sheet;
- as the device is designed to allow processing of the sheet on each of its faces by means of the same processing means, the distance between the axis of the large roller and the entry of the transfer path, downstream of the processing means is necessarily important to allow the sheet to be fully carried by the path and returned before being reintroduced into the processing means. This large distance therefore implies that the volume of a machine comprising this device is large;
- The curved part of the path risks deforming the processed document by permanently bending the sheet, while it is desired to obtain a flat sheet at the outlet of the device;
- The device described does not minimize the conveying time for documents of length less than the length of the turning curve.

 In general, the SHARP and XEROX devices have a large volume and a high complexity. Because of this complexity, the system has a high cost and its reliability as well as its yield, calculated as the number of sheets processed per unit of time, are reduced.

 The inventor therefore sought a less complex, more compact, less expensive double-sided sheet processing system capable of processing sheets of more variable length and flexibility than what the prior art allows.

To this end, the present invention relates to a sheet handling device comprising a transfer path for the latter, arranged between an inlet and at least one outlet, and comprising:
- At least a first means for moving a sheet arranged at the entrance to the transfer path and adapted to hold and move all or part of a sheet;
- A movable sheet pickup means, arranged downstream of the first means of setting in motion, adapted to grip the sheet in the vicinity of its leading edge and to move the latter in the direction of the exit from the transfer path; characterized in that the sheet pick-up means and the first movement setting means are furthermore jointly adapted to give the leading edge a speed lower than that of the sheet portion moved by the first setting-up means movement, a free loop thus forming between the first means of movement and the sheet gripping means.

 Thanks to these arrangements, the loop of the sheet is formed at least partially freely by the action of stresses distributed over a whole part of the surface of the sheet, linked in particular to gravity and to the natural rigidity of the sheet. However, it should be noted here that the loop can be supported to limit the stresses due to the action of gravity. Thanks to these provisions, the sheet undergoes only slight stresses. In particular, unlike the prior art, it is not forced to wrap around a roller and thus avoids the definitive deformation mentioned above.

 The free loop is not supported over its entire length, no large mechanical part is necessary and the device according to the invention can be of small volume. The speed of the leading edge of the sheet being low, the path it travels is short and the travel time can be optimized, that is to say here minimized, as a function of the length of the sheet. The device can have a compactness independent of the size and rigidity of the sheets to be handled, since it does not impose the curvature of the sheet and does not support the surface of the sheet.

 In addition, the loop can be made outside the system which incorporates the device according to the invention and thus further improve the compactness of this system. In this regard, the size of the sheet pickup device is not related to the length of the sheet. It is possible, if the sheet is very long, that a large-sized loop is formed outside the device.

Among other advantages of the invention:
- The device is particularly suitable for allowing the sheet to be processed to be turned over, for, in the context of use with a printer or a scanner, enabling the sheet to be processed on both sides;
- the sheet pick-up means makes it possible to handle a sheet in a safe manner: the leading edge of each sheet arriving in the turning device is pinched in said sheet pick-up means which leads it directly towards an exit from the transfer path;
the device makes it possible to minimize the handling time without increasing the speed of the conveying means.

 By its characteristics, the device according to the invention minimizes the number of electromechanical components, no complex control system being necessary and the device described here can be in the form of an optional unit easily adaptable to any type of machine. . When the device is intended for office use, it can also be present, integrated into a portable machine, because of its volume and its limited weight (the majority of the components can be made of plastic) and of its low complexity.

 Lower cost, such machines have, in addition, high reliability.

 According to a particular embodiment, the device which is the subject of the present invention comprises, at said exit from the path, at least a second sheet movement means adapted to move all or part of said sheet and the movable sheet pickup means is adapted to present the leading edge of the sheet to said second moving means.

 Thanks to these arrangements, the sheets can be conveyed by the second means of setting in motion and / or treated during the second movement.

 Preferably in this embodiment, the entry and exit of the transfer path are combined, the first and second means having a common structure and being adapted to make the sheet follow, respectively upstream and downstream of the path transfer, an identical route followed respectively in two opposite directions.

 Thanks to these provisions, the sheet can follow the same route twice, presenting its front and back successively to a means for processing one side of the sheet. These provisions thus make it possible for example to produce a printer or a duplex scanner.

 According to another embodiment, the maximum distance between the leading edge of the sheet and the first means of setting in motion is of the order of half the length of the sheet. As a variant, the distance between the leading edge of the sheet and the first means of setting in motion is less than half the length of the sheet.

 Thanks to these provisions, the device according to the invention is particularly compact.

 The present invention also relates to a printer, a scanner, a fax machine, a photocopier or a computer and, more generally, any office automation machine comprising at least one handling device as succinctly described above, for printing on both sides. leaves.

 The invention also relates to a sheet handling method comprising an operation of moving all or part of a sheet at the entrance to a transfer path and an operation of picking up and moving a sheet on the path of transfer, in the vicinity of its leading edge, characterized in that the speeds of these operations are jointly adapted so that the speed imparted to the leading edge is less than that of the portion of sheet moved by the first setting means movement, a free loop is thus formed between the entry of the transfer path and the leading edge of the sheet.

 A particular embodiment of the method of the invention consists in forming the transfer path and the free loop outside of an office machine of which a sheet outlet and a sheet inlet respectively constitute the inlet and the outlet of the path. transfer.

 This process has the same advantages as the corresponding device and these are therefore not repeated here.

Other characteristics and advantages of the invention will also emerge from the description which follows with reference to the appended drawings in which:
- Figure 1A is a schematic elevational view illustrating an office machine equipped with the sheet turning device according to the invention;
- Figure 1B is a perspective view of the office machine shown in Figure 1A;
- Figures 2A and 2B show a detail view of Figure 1A illustrating the sheet turning device respectively before performing a sheet turning and after this turning;
- Figure 3 is a perspective view of the sheet turning device corresponding to Figure 2B, at the end of a turning, the paper guide surfaces not being shown to facilitate understanding;
- Figure 4 is a perspective view of a mobile sheet turning unit shown in Figure 3, with partial cutaway;
- Figure 5 is a view of a sheet turning system according to arrow V in Figure 3;
- Figure 6 is a partial sectional view along the section plane VI of Figure 4, with partial cutaway;
- Figure 7 is a view of the sheet turning device according to arrow VII of Figure 2B;
- Figure 8A is a partial sectional view along the section plane VIII of Figure 3, showing the sheet turning device according to a first step of the turning process, as well as its control system;
- Figure 8B is a view along arrow III of Figure 3 with partial cutaway, corresponding to the same process step as Figure SA;
- Figure 9A is a partial sectional view along the section plane VIII of Figure 3, showing the sheet turning device according to a second step of the turning process, as well as its control system;
- Figure 9B is a view along arrow III of Figure 3 with partial cutaway, corresponding to the same process step as Figure 9A;
- Figure 10A is a partial sectional view along the section plane VIII of Figure 3, showing the sheet turning device according to a third step of the turning process, as well as its control system;
- Figure 10B is a view along arrow III of Figure 3 with partial cutaway, corresponding to the same process step as Figure lOA;
- Figure 10C is a partial view along arrow X in Figure 108;
- Figure 11 is a view along arrow III of Figure 3 with partial cutaway, according to a fourth step of the process;
- Figure 12 is a view along arrow III of Figure 3 with partial cutaway, according to a fifth step of the process;
- Figure 13 shows the speed diagram of the embodiment of the invention presented with reference to Figures 1 to 12;
- Figures 14 and 15 show a partial view of two mechanical parts in cooperation, incorporated in the embodiment of the invention presented in Figures 1 to 13 and in particular in Figures 10B and 11, at two different times of its operation;
- Figure 16A is a partial view along arrow XVI of Figure 2A, of a first embodiment of a mechanical assembly incorporated in the embodiment of the invention presented in Figures 1 to 13;
- Figure 16B is a partial view along arrow XVI of Figure 2A, of a second embodiment of a mechanical assembly incorporated in the embodiment of the invention presented in Figures 1 to 13
- Figures 17A, 17B and 17C are views along arrow III of Figure 3 of the mechanical assembly partially shown, at three different times of operation of the device;
- Figure 18 shows schematically successive positions of the sheet being turned, in the embodiment presented with reference to Figures 1 to 17;
- Figure 19 is a view of the same type as Figure 1A illustrating another form of office machine equipped with the sheet turning device according to the invention.

- Figure 20 shows a schematic view of a second embodiment of the present invention at the start of handling a sheet;
- Figure 21 shows a schematic view of the second embodiment of the present invention during the manipulation of a sheet;
- Figure 22 shows a schematic view of the second embodiment of the present invention during the handling of another sheet;
- Figure 23 shows the speed diagram of the embodiment of the invention presented with reference to Figures 20 to 22;
- Figure 24 is a schematic view of a third embodiment of the present invention during the handling of a sheet; and
- Figure 25 is a detail view of a fourth embodiment of the present invention, illustrating the sheet turning device.

According to the embodiment chosen and shown in FIGS. 1 to 18, a sheet handling device 1 according to the invention, which here turns over a sheet, is arranged in an office machine 60 comprising a processing member 63. It will be noted that this office machine 60 can in particular be:
an image forming apparatus and even more particularly a printer, the processing member 63 then being a printing member,
a scanner, the processing member 63 then being a reading member;
- A fax machine, the processing member 63 then comprising both a reading member and a printing member.

 The office machine 60 comprises, in a conventional manner, rollers 162 for successively taking individual sheets and driving them towards the processing members 63, other conveyor rollers 64A and 64B forming a first setting means. movement, and a sheet path 66 leading to the sheet turning device 1. These elements are of structure well known to those skilled in the art and already implemented in office machines. They are therefore not described further here. We note, however, that the sheets are moved along their length and that the office machine is adapted to process sheets in 210 x 297 mm format.

 A description will now be given, with the support of FIGS. 1 to 18, of a preferred embodiment of a sheet handling device (here turning) according to the invention. This device is located opposite the rollers 64A and 64B and makes follow at the leading edge of the sheet a closed-loop transfer path so that the sheet, leaving the rollers 64A and 64B, enters the transfer path and that after having followed the transfer path to its exit, the sheet returns between the rollers 64A and 64B in order to undergo a second treatment on the part of the treatment member 63.

 The sheet turning device illustrated is mounted on a frame made up of two side walls 20A and 20B (FIG. 3), themselves mounted on the main frame of the office machine 60. The side walls 20A and 20B are generally parallel to one another. the other and have a distance between them allowing the passage of the sheet to be handled. Conveyor rollers 2 (in this embodiment chosen and shown in FIG. 4 in particular, there are 3 conveyor rollers) are articulated between the two side walls 20A and 20B.

 Appropriate transmission means well known to those skilled in the art, transmit engine torque to the conveyor rollers 2.

Follower rollers 4 (in this embodiment chosen and shown in FIG. 4 in particular, there are three follower rollers 4 respectively opposite the three conveyor rollers 2) are also mounted between the side walls 20A and 20B and each of these follower rollers 4 is pressed against the corresponding conveyor roller 2 so that their axes are substantially parallel and that the follower roller 4 can rotate by the effect of
The drive exerted by said conveyor roller 2, possibly through a sheet taken between the conveyor rollers and the follower rollers.

 The conveyor rollers 2 and the follower rollers 4 are assembled in such a way that they form a sheet gripping means 90 (FIG. 9A) capable of holding a sheet in the sheet turning device and of conveying it when the conveyor rollers 2 and the follower rollers 4 rotate.

 More particularly, as shown in FIG. 4, during the conveying operation, the follower rollers 4 are always pressed against the corresponding conveyor rollers 2 by means of elastic compression means 47.

 A mobile turning unit 70, which includes the elements which accompany the leading edge of the sheet being turned, is shown in FIG. 4. It notably includes the conveyor rollers 2, mounted around a conveying shaft 3 which is supported by the side walls 20A and 208 (FIG. 3) respectively via the bearings 48A and 48B (FIG. 4), and the follower rollers 4, mounted around the same follower shaft 5, arranged parallel to a predetermined distance of the conveyor shaft 3 so that the follower rollers 4 can be pressed against the conveyor rollers 2 via the sheet during the conveying and turning operation. The follower shaft 5 is supported in free rotation by a sheet turning frame 80, incorporated in the mobile turning unit 70, by means of the bearings 48C and 48D.

 As shown in Figures 3 and 4 in particular, the sheet turning frame 80 has a rectangular bottom 81 and a first, a second, a third and a fourth side walls 82, 83, 84 and 85 (Figures 3 and 4 ) connected to each other, perpendicular to the bottom 81. The first side wall 82 and the third side wall 84, parallel to each other, are perpendicular to the second side wall 83 and the fourth side wall 85 which are between them , parallel. A fifth wall 86 (FIG. 4) is arranged parallel to the wall 82 at about a third of the distance from the wall 82 to the wall 84 towards said wall 84 and connected perpendicularly, on the one hand, to the bottom 81 and, from on the other hand, to the wall 85. The walls 82 and 84 exceed the walls 83 and 85 by at least the value of the diameter of the conveyor rollers 2 in the direction opposite to the bottom 81, forming protuberances.

 On each of these protrusions of the walls 82 and 84 is arranged a through hole receiving the bearing 48B, respectively 48A. Therefore, the bearings 48A and 48B have the dual function of positioning, on the one hand, the conveying shaft 3 articulated in the frame walls 20A and 20B, and on the other hand, the sheet turning frame 80 articulated around said conveying shaft 3, between a low position called "waiting position" (FIGS. 2A, 2B, 3, 4, 5, 6, 7, 8A, 8B, 9A, 9B and 12), in which the edge connecting the bottom 81 with the wall 85 is in abutment against an edge 20C of the wall 20A (see FIG. 5 in particular) and a high position called "inversion position" (FIGS. 10A, 10B, 10C and 11), in which edge connecting the bottom 81 with the wall 83 abuts against an edge 20D of the wall 20A.

 The side wall 20B of the frame and the side wall 82 of the sheet turning frame 80 are adjacent and parallel to each other.

Likewise, the side wall 20A of the frame and the side wall 84 of the sheet turning frame 80 are adjacent and parallel to each other.

 Between the bearing 48A, the bearing 48B respectively, and the bottom 81, a second oblong opening 84A (FIG. 5), 82A respectively (not shown), is arranged in the wall 84, the wall 82 respectively, so as to receive the bearing 48C (FIG. 4), the bearing 48D respectively, thus positioning, the sheet gripping means 90, inside the sheet turning frame 80.

 According to this embodiment, the distance between the conveying shaft 3 and the follower shaft 5 is at the intersection of a parallel plane and a plane orthogonal to the bottom 81.

 The oblong openings 82A and 84A allow the follower shaft 5 to move along the longest axis of the oblong shapes, that is to say to approach or move away from the conveying shaft 3, so that the sheet gripping means 90 accepts different sheet thicknesses.

 The elastic compression means 47, constituted by two spring blades, each exert a restoring force tending to bring the follower shaft 5 closer to the conveyor shaft 3. The folded spring blades as shown in FIG. 4, are fixed to the sheet turning frame in their center by screws (not shown) and bear at their ends on the follower shaft 5.

 A torsion spring 11 (FIG. 5) is articulated at one of its ends around a stud 75, riveted on the external face of the wall 20A of the frame of the turning device and at the second of its ends around a second stud 88 mounted integrally on the face of the wall 84 directed towards the outside of the frame 80.

 The torsion spring 11 exerts a restoring force tending to tilt the sheet turning frame 80 either in the waiting position or in the turning position, so as to bring the sheet gripping means 90 closer to the sheet passage 66, making it possible to reduce said sheet passage 66 and to produce it in a rectilinear manner, thus reducing the risk of jamming of the sheet.

 One of the ends of the conveying shaft 3 (the left in FIG. 3) which exits outside the side wall 20B of the frame of the turning device, is driven in rotation by a motor 30 (FIG. 3 ) with a double direction of rotation, by means of the toothed wheels 32 to 35 (FIGS. 2A and 3) and of a spring clutch mechanism 28 (FIG. 6).

 The motor 30 is mounted on a wall 120 which is part of the frame of the office machine 60 and which is arranged parallel to the wall 20B, to its left in FIG. 3.

 The spring clutch mechanism 28 is constituted by a toothed wheel 31, second output wheel of the planetary gear and clutch input wheel, receiving a torque delivered by the engine 30 via the toothed wheels 32 to 35 , a coil spring 29 and a toothed ring 26 (Figures 4 and 8B).

 The toothed wheel 31, mounted axially on said end of the conveying shaft 3, is extended along its axis of rotation, in the direction of the conveyor rollers 2 by a hub 31A (FIG. 6), called "input hub", while a hub 3A, called "outlet hub", extends the conveying shaft 3 in the direction of the toothed wheel 31 along the same axis of rotation and of diameter close to that of the inlet hub 31A.

 The spring 29, in the direction of winding on the left and whose inside diameter is, at rest, less than the outside diameters of the inlet and outlet hubs 31A and 3A, is force-fitted on said inlet hubs and output 31A and 3A. The rotation of the toothed wheel 31 in the clockwise direction, that is to say in the opposite direction of the winding of the spring 29, tends to tighten the spring 29 around the hubs 31A and 3A, making them integral one the other; the torque of the toothed wheel 31, delivered by the motor 30 via the toothed wheels 32 to 35, is transmitted to the conveyor rollers 2, via the conveyor shaft 3. The conveyor rollers 2 are then said to be "engaged of the 31 "motor gear.

 One of the ends of the spring 29, facing the toothed wheel 31, is bent radially in the opposite direction from the axis of the spring 29, thus forming a tab 29A (FIG. 6).

 When the toothed wheel 31 rotates clockwise, keeping the tab 29A fixed relative to the rotation of the toothed wheel 31 makes it possible to separate the hub 31A from the hub 3A, thereby stopping the rotation of the conveyor rollers 2. The rollers conveyors 2 are then said to be "disengaged from the drive gear 31".

The toothed wheel 31 also has a groove 31B, of diameter
The inside of the toothed wheel, (to the right in FIG. 6), with a diameter smaller than that of the foot cylinder of the teeth of the toothed wheel 31 and with a depth such that the cloth left between the outer edge of the wheel toothed 31, opposite the hub 31A, is sufficient to transmit the torque necessary for the proper functioning of the sheet turning device, required by the conveyor rollers 2 via the clutch mechanism 28, without irreversible deformation of said toothed wheel 31.

 The toothed ring 26 is formed by a cylinder 26A, of external diameter such that it can be received and guided freely in rotation by the groove 31B of the toothed wheel 31 on the one hand, and a row of teeth 27 distributed around a diameter substantially equal to the diameter of the cylinder 26A (in the preferred embodiment of the invention, chosen here) and described in more detail below, on the other hand.

 Its internal diameter is such that when the ring 26 is mounted in the groove 31B, it only interferes with the end of the lug 29A of the spring 29, mounted on the hubs 31A and 3A.

 A notch 26B is made in the cylinder 26A so that it allows to receive the tab 29A without initial deformation of the spring 29, in order to transmit to said tab 29A a force tangential to the diameter of the hub 3A to disengage the conveyor rollers 2 when said ring 26 is kept fixed relative to the rotation of the toothed wheel 31.

 In FIG. 4, one of the ends of the follower shaft 5 (the left in FIG. 3) exits outside the wall 20B of the frame of the turning device. A crown of teeth 21 is mounted there, integral with the follower shaft 5 so that when the conveyor rollers 2 rotate and transmit a torque to the follower rollers 4, the crown of teeth 21 rotates around the axis of the shaft follower 5 (Figures 8B, 9B, 11 and 12).

 According to the embodiment chosen, as will be described below, the conveyor rollers 2 only rotate clockwise. Consequently, the crown of teeth 21 only rotates counterclockwise. As shown in particular in FIGS. 8B and 9B, the crown of teeth 21 is composed of six identical teeth. Each of these teeth has a surface 21A arranged in a plane passing through the axis of the follower shaft 5 and oriented upstream of the direction of rotation of the crown of teeth 21 so that one of them cooperates with a stop, which will be explained later in the description, in order to stop the rotation of the follower shaft 5 around its axis.

 In FIG. 4, the mobile sheet turning unit 70 also includes a sheet detection arm 6, articulated on the sheet turning frame 80, between the side walls 82 and 86, around an axis 7A, which is intended to detect the presence of a sheet in the sheet gripping means 90. The axis 7A is arranged parallel to the axis of the follower shaft 5 and is located in the vicinity of the internal edge of the turning frame of sheet 80, at the intersection of the wall 85 with the bottom 81. The means of articulation of the sheet detection arm 6 around the axis 7A comprise a pin 7. In addition, it is formed in the wall 82 , on the internal side thereof, a cylindrical housing (not shown in the figures) of dimension complementary to the pin 7, the cylindrical housing having as axis the axis 7A.

Similarly, there is formed in the wall 86, on the side facing the cylindrical housing made in the wall 82, a parallelepiped housing 86A (FIG. 8A) having for axis, also the axis 7A and having a square section whose side is substantially equal to the diameter of the pin 7.

 The pin 7 is inserted into said complementary housings by deforming it elastically, the distance between these two housings being smaller than the length of the pin 7.

 The sheet detection arm 6 also includes an arm 8 connected at one of its ends to the pin 7, in the vicinity of the parallelepiped housing 86A and arranged between two pairs of consecutive rollers, in such a way that it allows the rotation of the arm sheet detection 6.

A contact surface 8A (Figures 4, 8A, 9A), having a substantial width so as not to damage the sheet arriving in the sheet pickup means 90, is arranged at the end of the arm 8, so that :
- When no sheet is present in the sheet pickup means 90, the contact surface 8A intersects the area defined by said sheet pickup means 90 (Figure 8A); and
- When a sheet arrives in said sheet gripping means 90, its leading edge 22 meets this surface 8A and pushes it so as to pivot the detection arm 6 around the axis 7A until the surface 8A no longer cuts the leading edge 22 of the sheet (FIG. 9A).

In FIGS. 4, 9A and 9B, the pin 7 also has at its end inserted into the housing of the wall 82 a flat 9 (the length of this flat will be explained below),
The sheet detection arm 6 comprises a second arm 10 also connected at one of its ends to the pin 7, between the arm 8 and the flat 9.

 According to the embodiment chosen, the arm 10 is arranged in a manner substantially orthogonal to the surface 8A and so that it allows the rotation of the sheet detection arm 6 described above. Figure 8B, a second contact surface 10A is arranged at the end of the arm 10 so that said contact area 10A lies in a plane parallel to the surface 8A.

 In the embodiment chosen and shown, the contact surface 10A is represented by a rounded surface, in order to limit friction of the latter on the surface against which it will abut (the function of the contact surface 10A will be described later in support of Figure 11).

 In Figures 4, 8B and 9B, a lever 15, which has a complementary housing to the flat 9 of the pin 7, is mounted so as to slide along said flat 9, parallel to the axis 7A.

 A contact zone 16B (FIG. 8B) is arranged in the vicinity of the pin 7 on the lever 15 which cooperates with a thrust zone 43A, in order to move the lever 15 along the pin 7.

 According to the embodiment chosen and shown, the lever 15 is composed of a body 16 and a head 17. The body 16 is generally of rectangular shape whose side facing the wall 82 has substantially a diamond shape, itself formed of two substantially triangular surfaces, 16A and 16B (FIGS. 8B and 9B), in the center of which is positioned the complementary housing 15A so that the large diagonal is substantially parallel to the center distance of the conveyor rollers with the follower rollers and orthogonal to axis 7A.

 The surface 16A is that which is closest to the sheet gripping means 90. The head 17, perpendicular to the body 16, is arranged in a cantilever at the end of the body 16, on the side of the surface 16A passing through the wall 82 thanks to a notch arranged for this purpose, such that it pivots about the axis 7, cooperating with the sheet detection arm 6 and that it is interposed in the space left between two teeth of the crown of teeth 21 (FIGS. 8B and 9B).

 In FIGS. 8B and 9B, the head 17 is a bar of triangular section, the apex 17A of which is directed towards the crown of teeth 21, one of its adjacent sides 17B collinear with the side of the surface 16A also directed towards the crown of teeth 21 and another of its adjacent sides 17C arranged in such a way that when the head abuts against the surface 21A of a tooth of the crown 21, the contact is limited to the apex 17A.

Therefore, when the lever 15 moves along the flat 9, the frictional force of the head 17 on the surface 21A is minimized.

 In FIG. 10C, the body 16 of the lever 15 also has, on its side facing the wall 86, a fixing device 18 capable of receiving a branch 19A of a torsion and compression coil spring 19.

 As shown in FIG. 4 in particular, the spring 19 is mounted around the pin 7. Its second branch 19B is threaded into an opening made in the bottom 81 of the sheet turning frame 80, so that it exerts a restoring force tending to bring the body 16 closer to the wall 82.

 The spring 19 also exerts a restoring torque, around the axis 7A, tending to bring the surface 8A of the sheet detection arm 6 towards the zone defined by the sheet gripping means 90.

 The action of the assembly constituted by the sheet detection arm 6, the lever 15 and the spring 19 could be carried out by an electromechanical or electro-optical sheet detector and an arm controlled by an electromagnet, mounted on the frame 80. However, this would require a more complicated control system and would make the turning unit 70 heavier, which would make it more difficult to rotate the turning unit 70 around the conveying shaft 3 because of the cables connecting these electronic components to the control system of the office machine 60 and the weight of these components.

 It can be seen (FIG. 4) that the assembly formed by the sheet turning frame 80, the follower shaft 5, the follower rollers 4, the bearings 48C and 48D, the sheet detection arm 6, the lever 15, the torsion and compression spring 19, the crown of teeth 21, the elastic compression blades 47 and the various means of fixing these parts, whether or not shown, form the mobile sheet turning unit 70.

 To achieve the function of rotation of the sheet turning unit 70 which will be described below, it is preferable to produce a maximum of parts making up the sheet turning device 1, made of plastic material, namely, in this embodiment preferred, the follower shaft 5, the sheet detection arm 6, the lever 15, the crown of teeth 21 and the sheet turning frame 80, which allows the configuration of the sheet turning device illustrated in the description which precedes.

 Similarly, it is necessary to have a large friction between the conveyor rollers 2 and the follower rollers 4 on the one hand and the sheet on the other hand.

For this, it is advantageous to use rubbers with a high coefficient of friction for the manufacture of said rollers.

 In order to disengage the conveyor rollers 2 from the toothed wheel 31, a mobile device is provided. As shown in FIGS. 2A, 2B and lOB in particular, this device essentially comprises a toothed wheel 38, of fixed axis, which cooperates with the wheel 37, a second wheel 39 which is idly mounted on a shaft parallel to the shaft of the wheel 38 and a support 50 on which the shaft of the wheel 39 is mounted integrally. The support 50 pivots freely around the shaft of the wheel 38, but is frictionally driven with it.

 The support 50 is substantially V-shaped. As shown in FIGS. 10B, 11 and 12 in particular, the axis of the wheel 38 is located substantially at the intersection of the legs of the V.

 On one of the two ends of said V is arranged a contact zone 51A (FIGS. 10B and 11), arranged so as to cooperate with the contact zone 10A (FIG. 11) of the sheet detection arm 6.

 On the other of the two ends of the V is arranged a contact zone 52A (FIGS. 2B, 10B and 12), arranged so as to cooperate, firstly, with a contact zone 24A then, secondly, with a contact area 24B of a cylindrical part 24 of a toothed wheel 23 mounted integrally on the sheet turning frame 80 on the side of the gear 38 (left side in FIG. 4).

 According to the embodiment chosen, the toothed wheel 23 is fixed to the outer face of the wall 82 of the frame 80 so that its axis and the axis of the conveying shaft 3 are combined.

 It can be seen in FIGS. 11 and 12 that the teeth of the wheel 23 are arranged on an arc of the said wheel 23 so that they cooperate with the toothed wheel 39 over a length less than that of the circumference of the wheel 23, returning the sheet gripping means 90 from the inversion position (Figure 11) to the standby position (Figure 12); said arc of the wheel 23 is defined by an angle substantially equal to the angle taken by the mobile turning unit 70, by turning from its turning position towards its standby position.

 As shown in FIGS. 6, 10C and 12, the cylindrical part 24 extends the toothed part of the wheel 23 concentrically, in the direction of the toothed ring 26. The external surface 24A of the cylinder 24 has a discontinuity 24B arranged so that that the outside diameter of the teeth of the ring 26 is between the diameters of the surfaces 24A and 24B, and that the contact area 52A cooperates with an abutment surface of a tooth of the ring 26, stopping the rotation of said ring 26 relative to the rotation of the gear 31, when the mobile turning unit 70 reaches its turning position (FIG. 10B).

 The surface 24B is situated in the extension of the distance between the centers of the conveying shaft 3 and the follower shaft 5, on the part of the wheel 23 which does not face the crown of teeth 21.

 The wheel 39 is located on the arm of the support 50 supporting the contact area 51A. The distance between the two shafts, on which the toothed wheels 38 and 39 are articulated, is equal to the sum of the radii of said toothed wheels 38 and 39, so that the latter cooperate permanently. However, owing to the fact that the mechanical means constituted by the support 50 pivots freely around the shaft of the wheel 38, the axis of the wheel 39 tends to move in the direction in which the wheel 38 rotates, by the action of a friction couple, that is to say thanks to friction. Thus, when the wheel 38 rotates in the direction indicated by the arrow 105 in FIG. 2A, the shaft of the wheel 39 moves in the same direction, until the contact area 52A of the mechanical means or support 50 meets the contact area 24A, interrupting the rotation of the mechanical means or support 50. The mechanical means or support 50 resumes its rotation in the direction indicated by the arrow 105, when the contact area 24B is presented in the area 52A, by the rotation of the mobile turning unit 70 and is definitively interrupted when the zone 52A cooperates with a stop zone, or face, 27A of a tooth of the ring 26 (as shown in FIG. 10B). It is noted that each tooth of the ring 26 is adapted to carry said face 27A, as soon as it is in contact with the support 50. The area 52A is arranged at the end of a protuberance 52 of the support 50, the protuberance 52 having a shape such that it can be housed between two consecutive teeth of the ring 26.

It can be seen in FIG. 10B that in the embodiment chosen and shown, the support 50 is movable around an axis of rotation,
The shaft of the wheel 38, placed on the side of the support of the face 27A, that is to say on the side of this face where the tooth is located.

 On the other hand, when the wheel 38 rotates in the direction indicated by the arrow 115 in FIG. 2B, opposite to that of FIG. 2A, and the turning unit 70 is in the turning position, the shaft of the wheel 39 moves in the same direction, until the wheel 39 meets the toothed part of the wheel 23, with which it cooperates in order to return the turning unit 70 to its standby position (FIG. 12).

 The sheet turning device 1 also comprises a swing 40 movable between an open position (FIGS. 2A, 2B, 3, 7 and 8B) and a closed position (FIGS. 10A, 10B and 10C).

 The swing 40 is adapted to cooperate with an elastic pushing element 14 tending to return it to the open position. The elastic pushing element 14 is in the form of a torsion coil spring (FIGS. 3 and 10B), integrated at one of its ends into the swing 40 by means of a hook 44 (FIG. 8B), and kept fixed relative to a stud 45, riveted on the wall 20B perpendicular to the axis of the conveyor shaft 3.

 The swing 40 also comprises a contact zone 42A (FIG. 7) and a thrust zone 43A (FIGS. 7 and 10C) and is articulated in such a way that when the contact zone 42A cooperates with a thrust zone 87 (FIG. 9A) , the swing 40 tends to assume its closed position, moving the thrust zone 43A towards the contact zone 16B.

 In other embodiments, the swing 40 can be articulated on the sheet turning unit 70 for example.

 It is observed in Figures 7 and 10C that the swing 40 is composed of a tilting body 41 on which are arranged a cylinder 42 and a pusher 43 so that the contact area 42A has a portion of the cylinder surface 42 opposite the thrust zone 87 defined by the outer surface of the intersection between the wall 83 and the bottom 81 of the sheet turning frame 80 when the latter is in the high position and in such a way that the thrust zone 43A is fitted at the end of a pusher 43.

 The motor 30 is provided for driving the conveyor rollers 2 of the sheet turning system and for driving the moving means comprising the conveyor rollers 64A and 64B (FIGS. 2A, 2B, 3, 8A, 8B, 9A, 9B and 10A). Similarly, the set of rollers, having the same conveying cycle as the rollers 64A and 64B, like the sheet picking rollers 162, the rollers of the processing members 63 and, in general, all of the rollers for driving the sheet incorporated in the office machine 60, can be driven by this same motor 30.

To simplify the description, only the drive of the conveyor rollers 64A and 64B is shown.

 To transmit the driving force of the motor 30 to the conveyor roller 64A and 64B, a unidirectional device is provided. This device essentially comprises a toothed wheel 35 integral with the output shaft of the motor 30, which cooperates with a toothed wheel 37 mounted integrally on the shaft of the conveyor rollers 64A, via a toothed output wheel of the secondary planetary gear 36 ( Figures 2, 3 and 17). When the output shaft of the motor 30 rotates in the direction indicated by the arrow 100 in FIG. 2A, that is to say the second direction of rotation of the input wheel 35, the means of setting in motion formed by the conveyor rollers 64A and 64B, drives the sheet from path 67 to path 66.

 When the motor output shaft rotates in the opposite direction, that is to say in that indicated by the arrow 110 in FIG. 2B, the first direction of rotation of the input wheel 35, the means of setting in motion , formed by the conveyor rollers 64A and 64B, drives the sheet from the path 66 towards the sheet path 67.

 On the other hand, to transmit the motive force of the motor 30 to the conveyor rollers 2, a bidirectional device is provided, in which the direction of drive of the conveyor rollers 2 is independent of the direction of rotation of the motor 30.

 To this end, two intermediate gearwheels 33 and 34 are provided here (FIG. 2A, 2B and 17), each mounted idler on a shaft parallel to that of the motor 30. The shafts of the intermediate gearwheels 33 and 34 are integral with a support 58 pivoting freely around the motor shaft 30, said support and the cam follower 58A which it carries being driven by friction by the motor shaft 30 and by the input wheel 35. The distance between l 'shaft of the second intermediate gear wheel 33, respectively of the first intermediate gear 34, and the motor shaft 30 is equal to the sum of the radii of the gear wheels 33, respectively 34, and 35, so that these three wheels constantly mesh.

 However, because the support 58 pivots freely around the motor shaft 30, the axes of the wheels 33 and 34 tend to move in the direction in which the wheel 35 rotates, due to friction.

 Thus, when the output shaft of the motor 30 rotates in the direction indicated by the arrow 100 in FIG. 2A, the shafts of the wheels 33 and 35 move in the same direction, until the intermediate wheel 34 meets a inverting output gear 32 with a fixed axis with which it cooperates. The reversing wheel 32 cooperates itself with the wheel 31 which, by means of the clutch mechanism 28, drives the conveyor rollers 2 if they are engaged from the wheel 31.

 Because the motive force is transmitted from the wheel 35 to the wheel 31 via the assembly of the two wheels 34 and 32, the direction of rotation of the wheel 31 is opposite to the direction of rotation of the wheel 35. In Figure 2A, where the wheel 35 rotates counterclockwise, the wheel 31 rotates clockwise.

 On the other hand, when the output shaft of the motor 30 rotates in the direction indicated by the arrow 110 in FIG. 2B, opposite to that in FIG. 2A, the shafts of the wheels 33 and 34 move in the same direction, until that the intermediate toothed wheel 33 meets the wheel 31, with which it cooperates.

 Because the motive force is, in this case, transmitted from the wheel 35 to the wheel 31 via the wheel 33 only, the direction of rotation of the wheel 31 is the same as the direction of rotation of the wheel 35. In FIG. 2B, the wheel 35 rotates clockwise, and the wheel 31 therefore also rotates clockwise, that is to say in the same direction as that of FIG. 2A.

 The set of intermediate toothed wheels 33 and 34, mounted on the support 58, forms a planetary gear 55 around the toothed wheel 35.

 In order to solve a technical problem which will be explained below in the operation of the device, this single drive means comprises a device for delaying the direction of rotation of the planetary gear 55, shown in FIGS. 16 and 17.

 To this end, the support 58 also includes a leg 58A forming a cam follower (FIGS. 17A and 17B) which carries at its end a contact surface 58B arranged so as to cooperate with a first cam 36B.

 It is advantageous to produce the support 58 in a material having a high elasticity and to arrange the cam follower 58A so that its contact surface 58B can be moved without irreversible deformation of its structure. The contact surface 58B can then cooperate permanently with the cam 36B, without any particular adjustment and whatever the shape of said cam 36B.

 In FIG. 16, the secondary wheel 36 is articulated on a shaft 98 integral with the wall 120 and is formed by the cam 36B comprising a lateral opening 36C, and by a row of teeth 36A making it possible to receive and retransmit the torque of the wheel 35 to wheel 37.

 Around the same shaft 98 is mounted a coil spring 123 in compression between the row of teeth 36A and a circlip 124, so that it exerts a restoring force tending to bring the cam 36B against the wall 120.

 According to the embodiment chosen and shown, the cam 36B is substantially cylindrical in shape and has a lateral opening, in the form of a triangular opening 36C opening facing the wall 120. Said opening 36C, carried by the first cam 36B , has a section, perpendicular to the first path followed on the first cam 368 by the cam follower 58A, the surface of which, in the second direction of rotation 117, increases then decreases, the decrease being faster than the growth since the wall of the opening reached last, in the first direction of rotation, is in a plane which passes through the axis of rotation of the first cam 36B.

 This opening 36C is arranged in such a way that it can receive the cam follower 58A when the secondary wheel 36, by turning in its first direction of rotation 116 (FIGS. 17B and 17C), presents said opening 36C opposite the cam follower. 58A.

 The hypotenuse of the triangular opening 36C forms a slope such that the action of the cam follower 58A, housed in said opening 36C, moves the secondary wheel 36 along its shaft, when the secondary wheel 36 continues to rotate according to its first direction of rotation indicated by arrow 116. the cam follower 58A then moves to a predetermined position, bearing on the shaft 98.

 The diameter of the first cylindrical cam 36B and the length of the cam follower 58A are such that they cooperate constantly, in particular when the secondary wheel 36 rotates in its second direction of rotation indicated by the arrow 117.

 As shown in FIG. 8A, the motor 30 is connected to a control power circuit 12. The control power circuit 12 is activated and controlled by a conventional office machine controller 13.

A bidirectional sheet presence detector 74, arranged in the path of the sheet 66 in the vicinity of the conveyor rollers 2, is also connected to the controller 13. In conventional manner, the controller 13 is, for its part, for example, connected and controlled by the user by the use of a control panel (not shown).

 In FIG. 16B, the same elements are found as in FIG. 16A, but on the one hand, a spring 123 separating the secondary wheel 36A and the cam 36B, and on the other hand, the secondary output wheel is not movable in translation along its axis. This particular embodiment is, compared to that presented in FIG. 16A, more compact, better protect against dust and the cam 36B has a lower inertia, which reduces the force necessary for its movement.

The operation of the device is as follows:
According to FIGS. 8A and 8B, when a user selects the duplex processing mode on the control panel of the machine, the motor 30 starts in the direction indicated by the arrow 100 in FIG. 2A. Its driving force is transmitted to the conveyor rollers 64A and to the conveyor rollers 2 according to the arrows 101 and 102 respectively (FIG. 8A).

 The planetary gear 55, comprising the input wheel 35, the intermediate wheels 33 and 34, the output wheels 31 and 32 and the secondary output wheel 36, is in the position shown in FIG. 17A. The intermediate gear 34 drives the inverting output gear 32 and the contact surface 58B of the cam support 58A of the support 58 follows the exterior surface of the cam 36B of the secondary wheel 36.

 The turning unit 70 is held in the standby position by the spring 11 (FIG. 5). The follower shaft 5 then rotates around its axis.

 A sheet 99, delivered by the processing members 63 and processed on its front, is conveyed by the conveyor rollers 64A and 64B inside the path 66 (FIG. 8A).

 According to FIGS. 9A and 9B, after having triggered the detector 74, the leading edge 22 of the sheet 99 enters the sheet gripping means 90. Its speed, which was previously equal to the speed of the portion of the sheet set in motion by the conveyor rollers 64A and 64B, therefore becomes equal to that of the conveyor rollers 2. At the same instant, said leading edge 22 pushes the surface 8A, causing the detection arm 6 to rotate around the axis 7A.

The head 17 of the lever 15, secured to the arm 6, enters between two teeth of the rotating crown 21, secured to the follower shaft 5. The top 17A of the head 17 comes into contact with the surface 21A of a tooth of the crown 21, which has the effect of stopping the rotation of the follower shaft about its axis: the leading edge 22 of the sheet 99 is jammed by the sheet gripping means 90.

 The speed of the leading edge 22 of the sheet 99 which is engaged with the sheet gripping means 90 therefore becomes zero, relative to the conveyor rollers.

 Thanks to the fact that the follower rollers 4 are pressed against the conveyor rollers 2 in accordance with the invention, the follower rollers 4 immobilized with respect to the conveyor rollers 2, rotate around the axis of the conveyor shaft 3, moving, by Consequently, the sheet gripping means 90 and therefore the leading edge 22 of the sheet 99 which describes an arc of circle, of diameter identical to that of the conveyor rollers 2.

 Note that definitely.

 The difference in speeds between the movement of the leading edge 22 of the sheet 99 and the rest of the sheet is carried out in a conventional manner, thanks to the difference in the ratio of teeth of the output wheels (here, the toothed wheels 31 and 37 ) on the number of teeth of the input wheel (here, the toothed wheel 35) and "or thanks to the difference in diameter of the conveyor rollers 2 and of conveyor 64A. In the example shown the number of teeth of the wheel 31 is twice that of the wheel 37 and the diameters of the rollers are equal.

The leading edge 22 of the sheet 99 is therefore moved by the sheet pick-up means 90 twice less rapidly than the rest of the sheet 99 by the movement means constituted by the conveyor rollers 64A and 64B.

 A loop 59 (FIGS. 10A and 10B) is formed, consequently, between the first means of setting in motion of the sheet, here consisting of the rollers 64A and 64B and the sheet taking means and in particular the rollers 2 and 4.

 Likewise, the turning unit 70 rotates around the axis of the conveying shaft 3 to its turning position, illustrated in FIGS. 10A, 10B and 10C.

 When the turning unit arrives in the vicinity of the turning position, the thrust zone 87 of the frame 80 pushes the surface 42A of the cylinder 42 of the swing 40. The swing 40 then turns around the axis of the stud 45, bringing the surface 43A of the pusher against the surface 16B of the lever 15, moving it towards the inside of the movable turning unit 70, in order to free the tooth of the ring 26 from the hindrance exerted by the head 17 of the lever 15, and to maintain it in this position as long as the mobile turning unit 70 is in the turning position. This operation makes it possible to loosen the sheet gripping means 90, so that it can convey the sheet 99 again in the path 66, back to the processing member 63.

 In parallel, the rotation of the turning unit 70 is stopped by the disengagement of the conveying shaft 3 of the toothed wheel 31 in the following manner: the toothed wheel 38 rotates in the direction indicated by the arrow 105 in FIG. 2A . The contact surface 52A of the protuberance 52 of the support 50 rotates in the same direction indicated by the arrow 105 and is stopped by the external surface 24A of the cylinder 24 of the toothed wheel 23, when the mobile turning unit 70 is between the waiting position and the turning position. When the mobile turning unit 1 arrives in the vicinity of the turning position, the cylinder 24 has its discontinuity 24B at the contact surface 52A of the protuberance 52, which allows the support 50 to continue its rotation indicated by the arrow 105 : the protrusion enters between two teeth of the ring 26 which rotates in the toothed wheel 31, until the surface 52A comes into abutment with the surface 27A of a tooth of the ring 26. Figure 14, the tab 29A of the spring 29 is then stopped, causing the diameter of the turns mounted on the hub 31A to increase. The embrace (the clamping force) of the spring on the hub 31A is then deactivated: The conveying shaft 3 is disengaged from the toothed wheel 31.

 The sheet gripping means 90 thus retains the leading edge 22 of the sheet 99 in the vicinity of the entrance to the path 66 until the trailing edge 25 of the sheet 99 leaves the path 66 and releases the detector 74.

 According to the invention, the sheet 99 takes a natural curve between the sheet gripping means 90 and the exit from the path 66. It is therefore neither permanently deformed nor marked.

 In FIG. 14, the increase in the diameter of the turns of the spring 29, mounted on the hub 31A, creates a restoring force which exerts a torque on the toothed ring 26 in the clockwise direction. As the support 50 is also driven by friction in a clockwise direction, and that the couples of the forces exerted by the spring, on the one hand, and by the mechanical means, on the other hand, s 'opposite, relative to the axis of rotation of the toothed ring 26, the toothed ring 26 and the support 50 are mutually blocked and therefore remain integral. The toothed ring 26 then constitutes a blocking means for the mechanical means consisting of the support 50.

 In fact, the face 27A of the toothed ring 26 exerts on the support 50 a force whose torque relative to the axis of rotation of the support 50 has a direction opposite to the friction torque exerted jointly on this support 50, by the shaft of the toothed wheel 38 and by the toothed wheel 38, with an intensity such that all of these elements remain static.

 In FIG. 15, the cooperation of the support 50 and of the ring 26 is observed, when the hub 31A, that is to say the toothed wheel 31, is stopped: the return force of the spring 29, described above, always gives the toothed ring 26, a torque tending to drive it clockwise. The torque due to the frictional forces exerted on the support 50 would not be enough to unlock it, and the toothed ring 26 and the support 50 would, again, be in a situation of mutual blocking, if there were not the system presented in Figures 16 and 17.

 This system is intended to create a delay in the change of direction of rotation of the output of the planetary gear 55, when the toothed wheel 35 changes direction of rotation.

 As shown in Figures 2B and 11, when the sheet 99 is outside the path 66, the release of the detector 74 sends a signal to the controller 13. As soon as the triangular opening 36C is in a predetermined position, the controller modifies the direction of rotation of the motor 30 along 110.

 In a simple manner, the triangular opening 36C returns to its predetermined position when the secondary wheel 36 rotates an integer number of revolutions for each sequence of the engine. Many systems well known to those skilled in the art allow this result, such as, for example, counting the number of steps of a stepping motor.

 In the embodiment chosen, the triangular opening 36C is in a position diametrically opposite to that opposite the contact surface 58B, relative to the shaft of the secondary wheel 36.

 FIG. 17B, when the motor 30 changes direction of rotation, according to arrow 110, the support 58, which tends to follow it by friction, is kept in its position, thanks to the fact that the contact surface 58B cooperates with the cam 36B, maintaining the intermediate gear 34 meshed with the reverse gear 32.

 The toothed wheel 31 then rotates in the direction 135, carrying with it the toothed ring 26 in the trigonometric direction, which has the effect of canceling the torque of the restoring force exerted on the toothed ring 26.

 The support 50, for its part, turns in the direction 115 and its protuberance 52 is released from the tooth 21 of the ring 26.

In FIG. 17C, when the triangular opening 36C comes opposite the cam follower 58A, the latter enters this opening, under the effect of the friction forces exerted on the support 58. The cam follower 58A then exerts on the cam 36B a force having a component parallel to its axis of rotation, force which moves cam 36B along said axis,
The support of the cam follower 58A then leaves the first path and thus reaches a predetermined position, here bearing on the shaft 98.

 It is now noted that the shaft 98 can carry a second cam of any shape suitable for following a second particular path to the cam follower 58A.

 Once the cam follower is in contact with the shaft 98, the intermediate gear 34 is released from the invert gear 32, while the intermediate gear 33 meshes with the gear 31.

The toothed wheel 31 then turns again clockwise.

 The toothed wheel 36, which carries the teeth 36A, the cam 36B and the lateral opening 36C, constitute a means of retaining the movable support 58. At least in the first direction of rotation 110 of the support 58, the toothed wheel 36 retains said mobile support by exerting on it a force opposite to the direction of rotation according to first predetermined rules taking into account the position of the input wheel 35, via the position of the secondary output wheel 36, the mobile support rotating thus in the direction of rotation 110 slower than the input wheel 35.

 The cam follower 58A follows, in fact, a path on the cam 36, without leaving it in the direction of rotation 100 of the input wheel 35, and leaving it in its direction of rotation 110 according to the following operation when the cam follower 58A is housed in the lateral opening 36C, the mobile support 58 passes from one extreme position of its movement to another. The lateral opening 36C constitutes a suitable path, in the second direction of movement of the cam, 116, for transferring the support of the cam follower 58A from the contact on the path of the cam 36B to a predetermined position. without pressing on said cam, this predetermined position being, for example pressing on a second path carried by the shaft 98 of the secondary wheel 36. When the input wheel 35 rotates in the first direction of rotation, 100, corresponding to the second direction of rotation 117 of the cam 36B, the cam follower 58A is moved from said predetermined position to its position shown in FIG. 17A.

 It is observed that, for a short time interval, corresponding to FIG. 17B, the rotation of the toothed wheel 31 has been reversed, while constantly, it rotates otherwise in the same direction, whatever the direction of rotation of the motor 30 .

 Thus, the driving force is transmitted to the conveyor rollers 2 in the same direction 102 also thanks to the clutch mechanism 28. On the other hand, the direction of rotation of the conveyor rollers 64A and 64B and of the toothed wheel 38 is modified (according to the arrows 106 and 115 respectively).

 As shown in FIG. 11, the conveyor rollers 2 are therefore once again integral with the toothed wheel 31 and the sheet gripping means 90 conveys the leading edge 22 of the sheet 99 again inside the path 66, but this time to the processing units 63 to process its back. When the leading edge 22 of the sheet 99 reaches the conveyor rollers 64A and 64B, the conveyor shaft 3 is again disengaged from the toothed wheel 31 because the means of setting in motion formed by these conveyor rollers 64A and 64B moves the sheet 99 more quickly than does the sheet pickup means 90. It will be noted that the clutch mechanism 28 has two functions, on the one hand, stopping the rotation of the sheet pickup means and, on the other hand, disengage said means when the sheet is taken up in the movement setting means.

 The support 50 rotates in the direction of arrow 115 until its surface 51A meets the contact area 10A of the arm 10 of the detection arm 6. 11 remains in this position until the sheet 99 leaves the gripping means. sheet 90.

 When the sheet 99 leaves the sheet gripping means 90, the detection arm 6 returns to its initial position in the turning unit 70 thanks to the torque exerted by the spring 19, as well as the contact area 10A, allowing the support 50 resume its rotation along arrow 115 until the gear 39 meets the gear 23 with which it cooperates, in order to return the sheet gripping means 90 to the standby position.

 The lever 15 returns to its initial position thanks to the restoring force exerted by the spring 19.

 The mobile turning unit 70 returns to its standby position when the wheel 39 reaches the non-toothed part of the wheel 23.

 It can be seen in FIGS. 1 to 12 that the maximum distance between the leading edge of the sheet and the means of setting in motion is less than half the distance, and more precisely of the order of one sixth, of the distance separating, on the sheet 99, the leading edge 22 and the trailing edge 25.

 FIG. 13 represents the speed diagram of the embodiment of the invention presented with reference to FIGS. 1 to 12.

In figure 13, the abscissa represents the course of time, with:
an instant T1 of the start of movement of the sheet 99 by the first movement means;
an instant T2 of start of detection of the sheet by the detector 74;
- An instant T3 of engaging the sheet on the sheet taking means;
- An instant T4 of rotation stop follower rollers 4 and start of movement of the sheet gripping means;
an instant T5 of end of displacement of the sheet pickup means;
an instant T6 of exit from the trailing edge 25 of the first means of setting in motion;
an instant T7 of the end of sheet detection by the detector 74, of the start of rotation of the conveyor rollers 2 and of the start of the second movement;
- An instant T8 of the leading edge of the sheet in the conveyor rollers 64A and 64B;
an instant T9 of the start of return of the sheet-taking means; and
- an instant T10 of end of return of the sheet pickup means; and on the ordinate (along three axes of the ordinate which are confused but have different origins and identical scales) are represented the linear speeds of displacement of the parts of the sheet respectively in contact with:
- the first means of setting in motion, curve Cl
- the sheet gripping means, curve C2;
- the second means of setting in motion, curve C3;
It can be seen, in FIG. 13, that between the instant T3 when the leading edge of the sheet is grasped by the gripping means and the instant T6 when the sheet is released by the first means of setting in motion, the speed of the leading edge of the sheet gripped by the sheet gripping means is less than the speed of the trailing edge of the sheet. The leading edge 22 of the sheet 99, which is gripped by the sheet pickup means, moves at a lower speed than the trailing edge 25 of the sheet and a free loop is formed between the first setting means in motion and the sheet gripping means.

 Figures 20, 21 and 22 illustrate a second embodiment of the invention in which the sheet gripping means are clamps and the transfer path has an inlet and a plurality of outlets for sorting the sheets.

 In FIGS. 20, 21 and 22 are shown a sheet 99 comprising a leading edge 22 and a trailing edge 25, a first sheet movement means 53, two second sheet movement means 54 and 57 and means for moving the sheet pickup means 56.

 In Fig. 20, the sheet 99, which is set in motion by the first setting means has reached the sheet pickup means.

It is in the position shown in FIG. 20 that the sheet gripping means, here consisting of a clamp controlled by an electromagnet, grips the sheet and prevents the further translation of the leading edge. The sheet gripping means then performs an initial rotation of a few degrees to force a loop 59 to form on one side or the other of the axis going from the first means of setting in motion to the sheet gripping means.

 In FIG. 22, a large loop 59 is formed and the sheet gripping means has made a rotation complementary to the initial rotation to present the leading edge 22 of the sheet 99 to the second moving means 57. At this instant , the sheet gripping means releases the leading edge 22 of the sheet while the first movement means has not yet released the sheet.

 In FIG. 21, a small loop 59 is formed and the sheet gripping means has made a rotation complementary to the initial rotation in order to present the leading edge 22 of the sheet 99 to the second moving means 54. At this instant , the sheet gripping means releases the leading edge 22 of the sheet while the first movement means has not yet released the sheet.

 Thanks to the invention, the loop is controlled in length and therefore in curvature so that the sheet is not damaged whatever the second means of movement chosen and whatever the angle that the sheet makes between the first and second means of setting in motion.

 FIG. 23 represents the speed diagram of the last embodiment of the invention presented above.

In FIG. 23, the abscissa represents the course of time, with an instant T11 of start of movement of the sheet 99 by the first means of movement, an instant T12 of engagement of the sheet on the means sheet gripping, an instant T13 of letting go by the engaging means during handling of the sheet 99 presented with reference to FIG. 21, an instant T14 of letting go by the engaging means during handling of sheet 99 presented opposite FIG. 22, an instant T15 of exit from the trailing edge of the first means of setting in motion; and on the ordinate (along three axes of the ordinates which are confused but have different origins and identical scales) are represented the linear speeds of displacement of the parts of the sheet respectively in contact with:
- the first means of setting in motion, curve C4
- the second sheet movement means 54, during the handling of sheet 99 presented with reference to FIG. 21, curve C5;
- The second sheet movement means 57, during the handling of sheet 99 presented with reference to FIG. 22, curve C6;
It is observed, in FIG. 23, that between the instant T12 when the leading edge of the sheet is grasped by the sheet gripping means and the instant T15 where the sheet is released by the first means of setting in motion , the speed of the leading edge of the sheet gripped by the sheet gripping means is less than the speed of the trailing edge 25 of the sheet. The leading edge 22 of the sheet 99, which is gripped by the sheet gripping means, moves at a lower speed than the trailing edge 25 of the sheet and the free loop which forms between the first means of movement and the sheet gripping means has characteristics which depend on these speeds.

In FIG. 18 are diagrammatically represented seven successive positions of the sheet being turned over by the device according to the invention
- Position P1 corresponds to the sheet being taken out of the treatment zone, between the conveyor rollers 64A and 64B, between the instants T1 and T2 presented in FIG. 13;
position P2 corresponds to the instant when the leading edge of the sheet is taken between, on the one hand, the conveyor rollers 2 and, on the other hand, the follower rollers 4, but before the axis of the latter does not move, between times T2 and T4;
the position P3 corresponds at a time approximately in the middle of the time interval of rotation of the conveyor rollers 2 and followers 4, around the axis of rotation of the conveyor rollers, between the instants T4 and
T5;
the position P4 corresponds to the instant when the trailing edge of the sheet leaves the treatment zone between the conveyor rollers 64A and 64B; it is noted that the conveyor and follower rollers are no longer in rotation since the conveyor shaft 3 is stationary; the position P4 being reached between the instants T5 and T6;
- Position P5 corresponds to time T7 when the sheet is fully released from the conveyor rollers 64A and 64B;
position P6 corresponds to the moment when, after the conveyor and follower rollers have resumed their rotation, the leading edge of the sheet has been driven by the conveyor rollers 2 towards the conveyor rollers 64A and 64B, and qu 'it is driven by the latter towards the treatment zone, between instants T9 and T10; and
- Position P7 corresponds to the passage of the trailing edge of the sheet between the conveyor rollers, after this trailing edge has been released from the conveyor rollers 2 and followers 4, at time T10.

According to the embodiment shown in FIG. 19, the sheet handling device 1 according to the invention, which here turns over a sheet in the manner presented with reference to FIGS. 1 to 13, is arranged in an office machine 60 comprising a processing member 63. It will be noted that this office machine 60 can in particular be:
an image forming apparatus and even more particularly a printer, the processing member 63 then being a printing member,
- a scanner, the processing member 63 then being a reading member;
- A facsimile machine, the processing member 63 then comprising both a reading member and a printing member.

 The office machine 60 comprises, in a conventional manner, a cassette 61, containing the paper on which the treatment is carried out, rollers 62 for successively picking up the sheets loaded in the cassette and for driving them towards the treatment members. 63, other conveyor rollers 164A and 164B forming a first means of setting in motion, and a sheet path 67. It is noted that the sheets are moved along their length and that the office machine is adapted to process sheets at format 210 x 297 mm.

 In addition, unlike the machine presented with reference to FIG. 1, that of FIG. 19 is adapted to perform on the sheet 1, that is to say a treatment of a single face, the sheet then only passing through the machine. once, or on both sides, with two passes of the sheet through the machine.

 A valve 65, opens in its position 65B (in dashed lines in FIG. 19), a path 66B with the sheet coming from the path 67 towards a receiving plate 68, by simultaneously closing a path 66. In its position 65A (in lines continuous in FIG. 19), the valve 65 opens the path 66A to the sheet going towards the sheet turning device 1, simultaneously closing the way 66.

 The sheet turning device according to the invention is located opposite the rollers 164A and 164B and makes follow at the leading edge of the sheet a closed-loop transfer path so that the sheet, leaving the rollers 164A and 164B, enters the transfer path and that after having followed the transfer path until it leaves, the sheet returns between the rollers 164A and 164B in order to undergo a second treatment on the part of the treatment member 63 .

 Unlike the office machine shown in FIG. 1A, the turning takes place here in an enclosure 69 mechanically linked to the frame of the office machine 60.

 According to a variant of the invention, presented in FIG. 18, in broken lines, the device implementing the invention comprises a sheet guide means 200 adapted to support the sheet close to the movable sheet pickup means consisting of the rollers conveyors 2 and follower rollers 4. The guide means, in combination with those of said rollers towards which the curvature of the sheet is oriented, here the conveyor rollers 2, has a greater radius of curvature than these rollers. Thus the radius of curvature of the sheet is greater than in the embodiments not using the variant considered and the risks of lasting deformation of the sheet are eliminated.

 In addition, in the variant shown in Figure 18, in broken lines, the sheet guide means is movable with the conveyor and follower rollers. During its movement, the sheet guiding means directs the free loop downward, correspondingly preventing the formation of the free loop above these rollers.

 In the third embodiment of the present invention, represented in FIG. 24, it is observed that a sheet support means 201 is adapted to support the sheet 99 substantially in the middle of the free loop formed between the conveyor rollers 64A and 64B forming the first means of setting in motion, and the conveyor rollers 2 and followers 4.

 Thanks to this sheet support means 201, the tensions exerted on the sheet, in particular near the rollers, are lower than in the other embodiments. The third embodiment applies particularly to the case where the free loop is of considerable length with respect to the width of the sheet, for example greater than the latter.

Finally, according to a variant shown in FIG. 25, when the direction of rotation of the input wheel changes, the change in position of the support 58 is retained by the action of a retaining means consisting of an electro- magnet 210, the position of which, retracted or extended, is controlled by the control means 12. The action of the retaining means is identical to that presented above for the other embodiments of the present invention. Compared to the other restraint methods presented above,
The electromagnet changes position at the same speed and at the same times of operation of the office machine 60. The modifications made to the embodiments presented above for the use of the electromagnets are obvious to the skilled in the art and are therefore not detailed here.

 According to a variant not shown, The shaft 98 carries a second cam which is not necessarily cylindrical, and, when the cam 36B rotates in its first direction of rotation 116, the cam follower 58A reaches a predetermined position, by following, on the second cam, a second path, possibly non-circular, which can, of course, take all the forms known in the field of cams.

 According to a variant not shown, the spring 29 is replaced by another type of elastic means, consisting of the shaft which supports the toothed wheel 26, said shaft comprising a part adapted to be used in elastic torsion when a tooth of said wheel is in abutment with support 50.

 According to another variant not shown, the support means of the cam follower 58A, when it has left the path carried by the cam 36B is a means of engagement of the cam follower 58A, adapted to maintain the cam follower in a predetermined position as long as the direction of movement 116 is maintained.

 According to yet another variant, not shown, the secondary wheel 36 does not mesh on the input wheel 35 and the drive means 30 has at least one friction drive means for driving the cam 36B.

 The scope of the invention is not limited to the means shown in the figures but extends, on the contrary, to variants, modifications and improvements within the reach of the skilled person.

Claims (23)

 1. Sheet handling device (99) comprising a transfer path (66,67) from the latter, arranged between an inlet and at least one outlet, and comprising:  - At least a first means of setting in motion (53, 64A, 64B) of a sheet (99) arranged at the entrance to the transfer path and adapted to hold and move all or part of a sheet;  - a movable sheet gripping means (2, 4, 90), arranged downstream of the first moving means, adapted to grip the sheet in the vicinity of its leading edge (22) and to move the latter in direction of exit from transfer path; characterized in that the sheet pick-up means and the first movement setting means are furthermore jointly adapted to impart to the leading edge a speed lower than that of the sheet portion moved by the first setting-up means movement, a free loop (59) thus forming between the first moving means and the sheet gripping means.  2. Device according to claim 1, characterized in that it comprises, at said outlet from the transfer path, at least one second means for moving the sheet (54, 55, 64A, 64B) adapted to move all or part of said sheet and in that the movable sheet gripping means is adapted to present the leading edge of the sheet to said second means of setting in motion.  3. Device according to claim 2, characterized in that the inlet and the outlet of the transfer path are combined, the first and second means having a common structure and being adapted to forward the sheet, respectively upstream and downstream from the transfer path, an identical route (66.67) followed respectively in two opposite directions.  4. Device according to any one of claims 1 to 3, characterized in that the maximum distance between the leading edge of the sheet and the first means of setting in motion is of the order of half the length of leaf.  5. Device according to any one of claims 1 to 3, characterized in that the distance between the leading edge of the sheet and the first means for setting in motion is less than half the length of the sheet.  6. Device according to any one of claims 1 to 5, characterized in that it comprises a drive means (30) common adapted to actuate the first means of setting in motion and the movable means for taking sheet.  7. Device according to any one of claims 1 to 6, characterized in that it comprises, arranged downstream of the first means of setting in motion at the entry of the transfer path, a means of detecting the trailing edge of the sheet (74) and a means for driving the movable sheet pick-up means (30), adapted to cause the leading edge of the sheet to reach the exit from the transfer path as soon as the detection means has detected the edge leaf leakage.  8. Device according to any one of claims 1 to 6, characterized in that it comprises, a means for measuring a predetermined displacement length in the direction of movement of the sheet, and a means for driving the means sheet gripping mobile (30), adapted to cause the leading edge of the sheet to reach the exit from the transfer path as soon as the measuring means has measured said predetermined length.  9. Device according to any one of claims 1 to 8, characterized in that the transfer path has a plurality of outlets (54,55) and in that the movable sheet pickup means (90) is adapted to direct the leading edge of the sheet in the direction of each of these outputs.  10. Device according to any one of claims 1 to 9, characterized in that the sheet gripping means (90) comprises at least two rows of sheet gripping rollers (2, 4) whose axes are parallel and means (47) for pressing up said rows of rollers, so that they are adapted to pinch the leading edge (22) of a sheet engaged between the two rows by the first means of setting in motion.  11. Device according to claim 10, characterized in that it comprises a means for rotating (30) said rollers, a means for moving the rollers and a means for detecting (8) sheet pickup between the rows of rollers , jointly adapted so that, when a sheet enters between the two rows of rollers, its presence is detected by the sheet pick-up detection means, a rotation of the sheet pick-up rollers is interrupted and the rollers are driven by the means travel to the exit of the transfer path.  12. Device according to claim 11, characterized in that said detector comprises a mechanical lever adapted to be set in motion by the leading edge of the sheet and a rotation blocking means mechanically connected to said detector and adapted to block rotation sheet picking rollers when the mechanical lever is actuated by said leading edge.  13. Device according to any one of claims 10 to 12, characterized in that the first means for setting in motion comprises conveyor rollers, in that the sheet pickup rollers are movable about an axis parallel to the axis of the conveyor rollers.  14. Device according to any one of claims 1 to 13, characterized in that it comprises a means for controlling the length of the loop adapted to control the speed of the leading edge (22) of the sheet (99) between the time when the leading edge of the sheet is grasped by the sheet pickup means (90) and the time when the sheet is released by the first moving means (64A, 64B).  15. Device according to any one of claims 1 to 14, characterized in that it comprises a sheet guide means (200) adapted to support the sheet near the movable sheet pickup means (2, 4, 90 ).  16. Device according to any one of claims 1 to 14, characterized in that it comprises a sheet support means (201) adapted to support the sheet substantially in the middle of said loop.  17. Printer, characterized in that it comprises a sheet handling device according to any one of claims 1 to 16 and a printing member (63) adapted to form an image on one of the two faces of the sheet upstream and / or downstream of the sheet transfer path.  18. Scanner, characterized in that it comprises a sheet handling device according to any one of claims 1 to 16 and a reading member (63) adapted to read information carried on one of the two faces of the sheet upstream and / or downstream of the sheet transfer path.  19. Fax machine, characterized in that it comprises a sheet handling device according to any one of claims 1 to 16 and a printing member (63) adapted to form an image on one of the two faces of the sheet and / or a reading member (63) adapted to read information carried on one of the two faces of the sheet, each said member being arranged upstream and / or downstream of the sheet transfer path.  20. Photocopier, characterized in that it comprises a sheet handling device according to any one of claims 1 to 16 and a printing member (63) adapted to form an image on one of the two faces of the sheet, said member being arranged upstream and "or downstream of the sheet transfer path.  21. Computer, characterized in that it comprises a sheet handling device according to any one of claims 1 to 16 and a printing member (63) adapted to form an image on one of the two faces of the sheet and / or a reading member (63) adapted to read information carried on one of the two faces of the sheet, each said member being arranged upstream and / or downstream of the sheet transfer path.  22. A method of handling a sheet (99) comprising an operation of moving all or part of a sheet at the entrance to a transfer path and an operation of picking up and moving a sheet on the transfer path , in the vicinity of its leading edge, characterized in that the speeds of these operations are jointly adapted so that the speed imparted to the leading edge is less than that of the portion of sheet moved by the first means of setting in motion , a free loop (59) thus forming between the entry of the transfer path and the leading edge (22) of the sheet.  23. Method according to claim 22, characterized in that it  consists of forming the transfer path and the free loop outside a  office machine including a sheet outlet and a sheet inlet  constitute respectively the entry and the exit of the transfer path.