EP0445029A1 - Paper sheet feeding device with pressing member - Google Patents

Abstract

A container (1) for receiving a stack (2) of sheets of paper is disposed in order that this stack is in an inclined position so as to be entrained, under its own weight, towards a rotary cylinder (3). The cylinder (3) frictionally interacts with the free face of the sheet disposed at one end of the stack (2) and a flexible strip (4), which is disposed on the path of the sheet thus entrained, and pressed against the said entrainment means (3) by a rigid pressing member (5) and mounted so as to move with two degrees of freedom, frictionally retains the sheets (21) other than that interacting with the cylinder (3). <IMAGE>

Description

The present invention relates to a device for feeding a machine with a series of sheets of paper arranged in a stack, comprising means for receiving the stack and means for separating each of the sheets from the stack.

Such a device finds its application in particular for office machines such as printers, photocopiers and fax machines, for example, the sheets of paper being, as the case may be, blank or already written.

Devices of the type defined above are already known, but these are complex and bulky, and require a motor to transport the sheets at the outlet of the receiving means, since these generally comprise a tray placed horizontally .

• les moyens de réception de la pile sont agencés pour que celle-ci se trouve en position inclinée afin d'être entraînée, sous l'effet de son propre poids, vers les moyens de séparation, et,
• les moyens de séparation comprennent des moyens d'entraînement coopérant par friction avec la face libre d'une des deux feuilles d'extrémité de la pile, et, sur le trajet des feuilles ainsi entraînées, une lame souple, pressée contre lesdits moyens d'entraînement par une semelle de pression rigide pour retenir, par friction, les feuilles autres que celle coopérant avec les moyens d'entraînement.

Document CH-A-538 985 also discloses such a device in which:

• the stack receiving means are arranged so that the latter is in the inclined position so as to be driven, under the effect of its own weight, towards the separation means, and,
• the separation means comprise drive means cooperating by friction with the free face of one of the two end sheets of the stack, and, on the path of the sheets thus entrained, a flexible blade, pressed against said means of drive by a rigid pressure sole to retain, by friction, the sheets other than that cooperating with the drive means.

In such a device, it is not necessary to provide a specific loading motor. In addition, the arrangement of the separation means directly at the outlet of the receiving means gives the device a compact structure, thus reducing its size. In addition, the delinting of the sheets from a stack of blank sheets is carried out automatically.

However, it is not possible in such a device to ensure a constant and reproducible pressure of the flexible blade on the sheets, without imposing severe manufacturing tolerances.

The present invention aims to overcome this drawback.

To this end, it relates to a device of the type defined above, characterized in that the pressure plate is mounted movable at two degrees of freedom corresponding to two rotations, one around an axis parallel to the path of the leaves, the other around an axis perpendicular to this path.

This automatically produces a suitable centering of the tilting pressure plate, which thus ensures constant and reproducible pressure on the sheets.

Advantageously, said pressure flange has two projecting edges perpendicular to the path of the sheets, in contact with said flexible blade.

Thus, the pressure on the leaves occurs in areas imposed by the projecting edges, and it is therefore better controlled.

In a first embodiment, said pressure sole is provided with two wings giving it the shape of a stirrup, and it is connected, by means of an articulation of the "gimbal" type, to an elastic blade built-in pressurization.

Such a device is particularly simple to make and to assemble.

In a second embodiment, said pressure soleplate is pressurized by at least one spring bearing on a fixed support, and the position of the spring is adjustable to distribute the pressure.

The device can thus be adapted to different types of sheets of paper.

Advantageously, a central stop is provided to limit the amplitude of the displacement of said sole in the direction perpendicular to the plane of the sheets during their journey.

This characteristic makes it possible to prevent the sinking of an excessively large bundle of leaves, the sole then coming, under the effect of the thrust exerted on the side of the bundle of leaves, to tilt against the central stop, which has to block the passage of the package on the opposite side. The device is self-locking, since the blocking is all the more effective the higher the number of pressed sheets.

Advantageously, elastic means are provided for returning the sheets against the drive means.

In this case, the friction force under the effect of which the sheet is driven is constant. This results in particular in a regular movement of the driven sheet.

Advantageously also, the drive means comprise a cylinder driven in rotation about its axis, the first generator of said cylinder in contact with said flexible blade is disposed after the elastic return means on the path of the sheets, and the distance between the two is seen from the axis of the cylinder at an angle between substantially 10 degrees and substantially 30 degrees.

These characteristics further improve the efficiency of the flexible retaining blade, as will be better understood below.

In the preferred embodiment, the friction surface of the drive means is made of a material whose coefficient of friction relative to the paper is greater than approximately the unit, and the flexible retaining blade is made of a material whose coefficient of friction relative to the paper is less than substantially the unit, and the dimension, in a direction perpendicular to that of the path of the sheets, of the friction surface of the retaining means is significantly less than that of the friction surface of the means in the same direction.

Advantageously, the drive means comprise a cylinder tangent along one of its generatrices to the end sheet with which they cooperate, and the flexible blade is arranged to form an angle with the sheets of the stack other than that cooperating with the drive means.

This embodiment is particularly simple, safe, and of a relatively low cost price.

• la figure 1 représente une vue de côté en coupe, simplifiée, d'un dispositif d'alimentation d'une machine de bureau en feuilles de papier,
• la figure 2 représente une vue de face, simplifiée, du dispositif de la figure 1,
• la figure 3 représente une vue de face, en coupe simplifiée, de la semelle de pression du dispositif de la figure 1,
• la figure 4 représente une vue du dispositif de la figure 1 en cours de fonctionnement, et,
• la figure 5 représente une vue d'une variante du dispositif de la figure 1.

The present invention will be better understood on reading the following description of two preferred embodiments of the device of the invention, made with reference to the appended drawings, in which:

• FIG. 1 represents a simplified cross-sectional side view of a device for feeding an office machine with sheets of paper,
• FIG. 2 represents a simplified front view of the device of FIG. 1,
• FIG. 3 represents a front view, in simplified section, of the pressure plate of the device of FIG. 1,
• FIG. 4 represents a view of the device of FIG. 1 during operation, and,
• FIG. 5 represents a view of a variant of the device of FIG. 1.

Referring to Figures 1 to 3, a device for supplying an office machine, here a fax machine, with a series of sheets of paper arranged in a stack is now described.

The device comprises a tray for receiving the stack 2 of sheets of paper, the bottom 1 of which is inclined relative to the horizontal, so that the stack 2 is driven, under the effect of its own weight, on the side of the lower horizontal edge 11 of tray 1.

Along this edge 11 is disposed an assembly intended to separate each of the sheets from the stack 2. This assembly comprises in particular a cylinder 3, circular and with an axis parallel to the edge 11, arranged here so that the sheet 21 most bottom of the stack 2 is substantially tangent to the surface of the cylinder 3.

The surface of the cylinder 3 is here made of rubber with a hardness of less than substantially 30 shores A, and its coefficient of friction with respect to the paper is of the order of 1.2. The dimension of the cylinder 3 along its axis is at least of the order of magnitude of the dimension of the sheets in the same direction. The cylinder 3 is driven in rotation about its axis by a motor and an appropriate drive mechanism, in the direction indicated by the arrow 33, which corresponds to the friction drive of the sheet 21 out of the tray.

Metal blades 32, here 2 in number, resiliently recall the sheets of stack 2 against the cylinder 3. The blades 32 each extend in a plane forming with the plane of the bottom 1 of the tank an acute angle α , and their ends press the sheets of the stack 2 at points situated substantially on the tangent generatrix T between the cylinder 3 and the sheet 21. The blades 32 here have curved ends, in particular so as not to damage the sheets, or , in the absence of leaves, the surface of cylinder 3.

The blades 32 are fixed on the upper part 12 of the receiving tank, which forms with the bottom 1 an angle less than the angle α, thus helping to separate the sheets from stack 2.

A rubber blade 4, here with a hardness of the order of 60 shores A, and a coefficient of friction with respect to the paper equal to 0.9, is fixedly mounted in abutment against the cylinder 3. The contact zone between the blade 4 and the cylinder 3 extends on the path of the sheet 21 when the latter is driven by the cylinder 3. Here, the blade 4 is fixed so that its face turned towards the side of the cylinder 3 extends, in its part upper, in the same plane as the blades 32. However, because the rubber blade 4 is longer than the metal blades 32, and because of its different flexibility, it bends so that the area on which it is is in contact with the cylinder 3, delimited by a generator of the cylinder 3, or contact generator, denoted C in FIG. 1, or placed after the generator T in the path of the sheets and at a distance therefrom. Here, the angle β under which is seen, from the axis of the cylinder 3, the portion of the cylinder 3 between the generatrices C and T, is of the order of 15 degrees. The angle β could be between substantially 10 degrees and substantially 30 degrees.

The flexible blade 4 is pressed against the cylinder 3 by a pressure plate 5, rigid and movably mounted with two degrees of freedom, so that the flexible blade 4 follows the shape of the cylinder 3 beyond the contact generator vs.

As shown in Figure 3, the pressure plate 5 is provided with two wings 53 and 54 which give it the shape of a stirrup. Each of the wings 53 and 54 is provided with an oblong slot in which an end 551 and 552 engages respectively, with a axis 55 parallel to the axis of the cylinder 3. The axis 55 comprises a rounded bulged part 553 which bears against the sole 5 itself. The axis 55 is connected to a recessed elastic blade 6 for pressurizing, which thus presses the sole 5 against the blade 4.

The sole 5 is therefore movable in rotation about the axis 55 perpendicular to the path of the sheets, and, thanks to the oblong slots of its wings 53 and 54, around an axis parallel to this path. Each of these rotations corresponds to a degree of freedom, the arrangement which has just been described forming an articulation of the "gimbal" type between the sole 5 and the embedded elastic blade 6.

The sole 5 also comprises two edges 51 and 52, parallel to the axis of the cylinder 3, and therefore perpendicular to the path of the sheets, in contact with the flexible blade 4.

As shown in FIG. 2, on which the sole 5 has not been shown for the sake of simplicity, the dimension of the blade 4, along the axis of the cylinder 3, that is to say perpendicular to the path of the sheets, is notably lower than that of the roller 3, and the blade 4 extends in the central part of the roller 3, the blades 32 being arranged here on either side of the blade 4.

The device which has just been described operates as follows.

When the cylinder 3 is rotated about its axis in the direction of the arrow 33, the lowest sheet 21 of the stack is driven by friction of its free underside with the cylinder 3, because that it is recalled by the metal blades 32 against this cylinder 3.

If the sheet 21 slides without difficulty against the sheet of the immediately upper stack, it is the only one to be driven. However, it is frequent that the sheet 21 carries with it one or more sheets of the stack, in particular because the coefficient of friction between the various sheets of paper is too high, or else because the sheets remain integral with each other. others by the roughness of their edges.

Such a situation, where several sheets of the stack 2 are entrained is shown in FIG. 4, where it appears that the rubber blade 4, arranged in the path of the sheets thus entrained, retains the sheets other than the sheet 21 which cooperates with cylinder 3. Blade 4 retains the sheets for two reasons. On the one hand, the leaves other than the sheet 21 form with the blade 4 an angle denoted γ which means that they tend to remain blocked against the blade 4. This is in particular due to the offset between the generatrices T and C. D ' on the other hand, if despite everything the sheet placed immediately above the sheet 21 is entrained in the contact zone between the blade 4 and the cylinder 3, it will be retained, by friction, by the blade 4.

Indeed, in the case where only the sheet 21 is driven between the blade 4 and the cylinder 3, the friction force between the blade 4 and the sheet 21 is less than that between the cylinder 3 and the sheet 21, which has as a consequence the driving of the sheet 21. However, the frictional force of the blade 4 is sufficient to retain, by friction, any sheet other than that which cooperates with the cylinder 3.

Thus, the separation of each of the sheets from the stack 2 is ensured by the cooperation of the cylinder 3 which directly drives a single sheet, and of the blade 4 which retains the sheets other than that directly driven, but which could nevertheless s 'be found entrained indirectly.

The pressure plate 5, due to its two degrees of freedom, is automatically put in place, and ensures constant pressure.

In Figure 5, there is shown a variant of the device of Figure 1, in which the same elements have the same references. The device of FIG. 5 essentially differs from that of FIG. 1 by the shape and the mounting of the sole. The sole 5 ′ of FIG. 5 is provided with projecting edges 51 ′ and 52 ′, here more rounded than the edges 51 and 52, and fasteners 53 ′ each comprising an oblong lumen which cooperates with a fixed axis integral with a rigid support 8. One or more springs 6 ′, here coil springs, are arranged between the support 8 and the sole 5 ′ to put it under pressure. The position of the line of action D of the springs 6 ′ is adjustable, by means of lugs not shown for the sake of simplicity, cooperating with each of the ends of the springs 6 ′. The sole 5 ′ is therefore, like the sole 5, movable around two perpendicular axes, and the distribution of the pressure between the edges 51 ′ and 52 ′ is adjustable by varying the position of the springs 6 ′.

To prevent the sinking of a large bundle of sheets, an adjustable stop is provided, here a simple screw 9, cooperating with a threaded hole in the support 8, and which limits the amplitude of movement of the sole 5 ′ in the direction perpendicular to the plane of the sheets during their journey. In addition, the screw 9 is in a central position relative to the sole 5 ′, so that when the sole 5 ′ abuts against the screw 9, the lifting of the edge 52 ′ by the sheet pack 2 causes the tilting of the sole 5 ′ around its point of contact with the screw 9, in order to bring the edge 51 ′ of the cylinder 3 and thus prevent the package of sheets from passing under the flexible blade 4.

Naturally, the present invention is not limited to the embodiment which has been described, and it is in particular within the reach of the skilled person to determine, for the cylinder 3 and the blade 4, materials other than those which have been described, by combining the friction forces to achieve the desired result. Good results are obtained when the coefficient of friction of the blade 4 relative to the paper is less than unity, that of the cylinder 3 relative to the paper being greater than unity.

Furthermore, it would be possible to provide, instead of driving the sheet of the stack disposed at its lower end, a drive of the sheet disposed at the upper end of the stack, by friction with its free face, which would then be the top side of the sheet.

Claims (9)

Device for feeding a machine with a series of sheets of paper arranged in a stack (2), comprising means (1) for receiving the stack and means (3, 4) for separating each of the sheets from the stack (2), device in which: - The receiving means (1) of the stack (2) are arranged so that it is in the inclined position so as to be driven, under the effect of its own weight, to the separation means (3, 4 ), and, the separation means comprise drive means (3) cooperating by friction with the free face of one (21) of the two end sheets of the stack (2), and, on the path of the sheets thus entrained, a flexible blade (4) pressed against said drive means (3) by a rigid pressure plate (5; 5 ′) to retain, by friction, the sheets other than that (21) cooperating with the drive means (3), characterized by the fact that the pressure plate is mounted movable at two degrees of freedom corresponding to two rotations, one around an axis parallel to the path of the sheets, the other around an axis perpendicular to this path. Device according to claim 1, in which said pressure plate (5; 5 ′) has two ridges (51, 52; 51 ′, 52 ′) projecting perpendicular to the path of the sheets, in contact with said flexible blade (4). Device according to one of claims 1 and 2, in which said pressure plate (5) is provided two wings (53, 54) giving it the shape of a stirrup, and it is connected, by means of a joint of the gimbal type, to a recessed elastic blade (6) for pressurization. Device according to one of claims 1 and 2, in which said pressure plate (5 ′) is pressurized by at least one spring (6 ′) bearing on a fixed support (8), and the position of the spring ( 6 ′) is adjustable to distribute the pressure. Device according to one of claims 1 to 4, in which a central stop (9) is provided for limiting the amplitude of the displacement of said sole (5 ′) in the direction perpendicular to the plane of the sheets during their journey. Device according to one of claims 1 to 5, in which there are provided elastic return means (32) of the sheets against the drive means (3). Device according to one of claims 1 to 6, in which the drive means comprise a cylinder (3) driven in rotation about its axis, the first generator (C) of said cylinder (3) in contact with said flexible blade ( 4) is arranged after the elastic return means (32) on the path of the sheets, and the distance between the two is seen, from the axis of the cylinder (3) at an angle (β) between substantially 10 degrees and substantially 30 degrees. Device according to one of claims 1 to 7, in which the drive means comprise a cylinder (3) tangent along one of its generatrices (T) to the end sheet (21) with which they cooperate. Device according to one of claims 1 to 8, in which said flexible blade (4) is arranged to form an angle (γ) with the sheets of the stack (2) other than that (21) cooperating with the drive means (3).

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