Device For Placing Sheets For A Printer

Abstract

At least two sheet conveyors are provided in such a way that several of these conveyors can rotate around the common axis, essentially independent of one another, and thus one of these sheet conveyors is ready to accept or detect the next sheet, if another of these sheet conveyors is still occupied with the transport or the placement of a preceding sheet and that a sensor is coupled mechanically with several of these sheet conveyors.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplified embodiment of the device, in accordance with the invention, from which it is possible to deduce other inventive features, but to which the invention is not restricted in its scope is shown in the drawing. The figures show the following:

FIG. 1 is a perspective view of a device, in accordance with the invention;

FIG. 2 is a perspective partial view of the device, in accordance with FIG. 1;

FIG. 3 is a sectional view of the device, in accordance with FIG. 1, with a sectional plane, transverse to the rotational axis of the sheet conveyor and the sheet guide;

FIG. 4 is a second sectional view of the device, in accordance with FIG. 1, parallel to the section, in accordance with FIG. 3;

FIG. 5 is a detailed view of FIG. 4;

FIGS. 6 through 8 show an outside holding-down element, in accordance with FIGS. 4 and 5, in different positions; and

FIGS. 9 and 10 are other perspective partial views of the invention.

DETAILED DESCRIPTION OF THE INVENTION

In the rotating sheet placement system (FIG. 1), in accordance with the invention, there is at least one rotating gripping element (pair 5) on at least one sheet conveyor, which, jointly with a sheet guide 6, turns a sheet to be placed in a stack by 180°, from a paper path, and conveys it to a stack edge 2. It is important thereby that after each placed sheet, the stack level is again detected, so that the placement mechanics is not blocked by a growing stack 1 and in the end, is damaged. Therefore, it is necessary to detect the new stack level and perhaps to lower a tray on which the sheets are placed.

For this reason, sensors and holding-down elements 3, 4 are needed, which can be lowered to the stack 1, after the sheet has arrived at the stack edge 2 with its front edge and is no longer pushed any further. The lifting of the holding-down elements 3, 4 is always necessary when the next sheet is conveyed to the stack edge 2 (the path for the next sheet must be released). What is important in the recognition of the stack level is that the entire width (along the stack edge 2) must be inspected so that a crushing and finally, a shifting of the sheets or even of the entire stack 1 does not occur. In addition, however, not only the topmost stack level is of interest, however, but rather also the possible lowest level, because only these two values, together, permit a statement regarding the inclined position of the stack 1. After a certain inclined position, in any case, one can expect a side sliding of the stack 1. The result is the requirement for a multi-part level detection system.

In the solution, in accordance with the invention, a three-part level detection system with three sensors and holding-down elements 3, 4 is shown. It can be arbitrarily refined, however, which means that the segmentation can be arbitrarily increased.

“Three-part” means that a holding-down element 3 is located in the middle of the rotating placement system (between the rotating sheet conveyors of the depicted exemplified embodiment), and two other holding-down elements 4 are located outside the rotating conveyors. In accordance with FIG. 1, in particular, the structure depicted by way of example is as follows:

Special triggering mechanics are required for the lifting and lowering process, which must operate as a function of the position of gripping elements 5.

So that it is possible to dispense with a separate drive for the lifting and lowering movement and the corresponding control and regulation device, which would have to ensure the synchronization of the two systems, a roller element 9 is located on the sheet conveyor or on its swivel arms, via a bearing arm 10. These roller elements 9 introduce corresponding swivel movements of the stack level detection system.

The level recognition system has, as the basic element, a carrier 8, which is supported so that it can rotate on an axis, on which the individual sensors 3, 4 are also located. A link piece 7, on which the roller elements 9 of the sheet conveyors run, is constructed on the carrier. “Run” means that the roller elements first lift the carrier or introduce a swivel movement of the carrier around the rotation axis. After a sufficient rotating movement, which results, in the end, in a sufficient lifting of the holding-down elements, this level must be held over a time distance. This is attained by a radius contour on the link piece 7. When the roller element 9 runs through this radius area, no other swivel movement of the carrier 8 is carried out, but rather only this position is held, whereas the gripping elements 5 with the roller elements 9 continue to rotate.

The radius area located on the link piece 7 must be placed in such a manner that it has, at the highest lifted position, a radius with reference to the center of the sheet conveyor. Only in this way is a persistence in the lifted position of the carrier 8 attained, whereas the sheet conveyors continue to rotate.

If the sheet to be placed comes to a standstill, with its front edge, and the operating gripping element 5 is withdrawn below the sheet behind the stack edge 2, so that the sheet can fall free onto the stack 1, then the link piece 7 is again released via the running roller element 9. The carrier 8 falls either due to its own weight or again suddenly falls back, spring-loaded, to its starting position. Finally, as will be described below, the holding-down elements are returned onto the stack 1, as quickly as possible, so that in time, before the arrival of the next sheet, the stack level detection is carried out and the tray height can be appropriately corrected.

As indicated up to now, the carrier 8 assumes, all total, two positions, a highest and a lowest position. On the way from the lowest position to the highest position, the carrier 8 must collect the individual holding-down elements 3, 4 and also move them to the highest position, so that the next sheet to be placed can move freely to the stack edge 2. The construction is done in such a way that the holding-down elements 3, 4 can assume any arbitrary stack position (proceeding from the lowest to the stack zero position), without being impaired thereby by the position of the carrier 8.

FIGS. 3 and 4 show that during the lifting movement, the carrier 8 collects the individual holding-down elements 3, 4 via flaps. Rubber dampers 17, which moderate the impact of the carrier 8 on the holding-down elements 3, 4 and also reduce the generation of noise, are located on the carrier flaps. The holding-down elements 3, 4 are gradually collected on the way to the highest lifted position.

In the highest position, all holding-down elements are located at a level in which they cannot hinder the next conveyed sheet. After this next sheet is placed on the stack edge, the individual holding-down elements 3, 4 are again released. With this release by the carrier 8, which falls back to its lowest position, the holding-down elements 3, 4 are also moved to their individual lowest position, specified by stack 1. At this moment when the individual holding-down elements strike the stack 1, there is no contact with the carrier 8. The holding-down elements 3, 4 thus operate, once more, independently of one another, until the next lifting process is again introduced.

FIGS. 2 through 5 show that below the holding-down elements 3, 4, forked light barriers 13 are placed on a basic frame, which detect both extreme positions of the stack 1 (zero position—highest stack position and lowest possible stack position). Per holding-down element 3, 4, therefore, two forked light barriers 13 on forked light barrier holders 11, 12 are needed.

If the zero position is exceeded by a holding-down element, the tray, on which the stack 1 is located, is correspondingly lowered; if, in addition, the possible lowest position is sensed on a holding-down element 3, 4, then the placement process is interrupted, because with a further increase in the stack, one can then expect a tilting over or a sliding away of the stack.

By this system, a low-cost solution has been found, in which, in a simple mechanical manner, several level inspections with regard to the stack can be simultaneously carried out. In the end, by only the carrier system, which is actuated by the sheet conveyers, many individual holding-down elements 3, 4 are controlled.

Moreover, advantageously, the link piece is also constructed along its guide contour with a rubber cover, so that the striking roller element 9 transfers the striking impact dampened and hereby also, the generation of noise is reduced to a minimum.

Only the carrier 8 can be provided with springs. Also the individual holding-down elements 3, 4 can be provided with springs in the direction of the lowest stack position, so that the movement returning to the stack 1 can be carried out as quickly as possible.

The function and execution of the forked light barrier inspection can be explained with the aid of FIGS. 4 through 8 in particular:

An individual switch flag 15, 16 on all three holding-down elements 3, 4, is constructed in such a way that an area and three extreme positions can be recognized. The switch flag 15, 16, has a small slit for this condition. If the holding-down element 3, 4, is located in the lifted, uppermost position (the next sheet is being placed), then the upper forked light barrier 13, is covered by the correlated switch flag 15, 16. The lower forked light barrier 13 is not interrupted.

Only if the stack zero position is reached does the contacting of the two forked, light barrier 13 change. The slit, which is located in the switch flag 15, 16, only just releases the upper forked light barrier 13; the lower forked light barrier 13 is, as before, not yet interrupted.

If the holding-down element 3, 4 is lowered furthered, then the lower forked light barrier is also interrupted. The upper forked light barrier is thereby switched free. Once again a change occurs if the maximum lowest position of the holding-down element is reached. Then, both the upper and also the lower forked light barrier are closed. By evaluating the two forked light barriers together, it is possible to make a reliable statement at to the site and the area in which the holding-down element is located. The following table shows the dependencies:

	Upper forked	Lower forked
	light barrier	light barrier
Uppermost holding-down element	Yes	No
position; lifted position
Stack zero position	No	No
Position between the aero and lowest	No	No
positions
Maximum lowest position of the stack	No	No
The meanings are as follows:
Forked light barrier interrupted: Yes
Forked light barrier not interrupted: No

The forked light barriers must be inspected with a UND linkage. Only in this way can the individual area position or extreme position be recognized.

FIG. 4 shows, especially, a holding-down element 4 in the deepest possible stack position; FIGS. 6 through 8 show the three possible extreme positions of the outside holding-down element 4, namely, the lifted position, the stack zero position, and the lowest stack position.

FIGS. 9 and 10 show, once more, other perspectives, in particular, the arrangements of the forked light barriers.

PARTS LIST

• 1. Stack
• 2. Stack edge
• 3. Holding-down element, middle
• 4. Holding-down element, to the right and to the left
• 5. Gripping elements of the sheet conveyor
• 6. Sheet guides
• 7. Link piece
• 8. Carrier
• 9. Movement-triggering roller elements
• 10. Bearing arms (steering elements)
• 11. Forked light barrier holder for outside holding-down elements
• 12. Forked light barrier holder for middle holding-down element
• 13. Forked light barriers
• 14. Holder and rotating point for the carrier and the holding-down elements
• 15. Switch flag for the triggering function of the forked light barriers on the middle holding-down element
• 16. Switch flag for the triggering function of the forked light barriers on the outside holding-down elements
• 17. Cushion

Claims

1. Device for the placement of sheets for a printer, including at least one rotating drivable sheet conveyor, which is provided to accept or grip a front edge of a sheet and for the placement of the sheet on a stack of sheets after traversing a rotation path, and a sensor device for the detection of the attained stack height and the attained stack level, which has a sensor, which simultaneously functions as the holding-down element for the stack, which is lifted, mechanically controlled, from the stack, for the release of the stack, so as to place the next sheet on the stack; said device characterized in that; at least two sheet conveyors are provided in such a way that these several sheet conveyors can rotate around a common axis, essentially independent of one another, and thus one of these sheet conveyors is ready to accept or detect the next sheet, if another one of these sheet conveyors is still occupied with the transport or the placement of a preceding sheet and that the sensor is coupled mechanically with several of these sheet conveyors.

2. Device according to claim 1, characterized in that a sheet guide, operating together with the sheet conveyor, is provided, wherein the sheet guide with a jacket surface serving as a placement for the sheet essentially specifies a curvature path for the sheet to be conveyed and each sheet conveyor has at least one gripping element to grip the accepted front edge of the sheet, in such a way that the front edge of the sheet is gripped and conveyed between one of these gripping elements of a sheet conveyor and the jacket surface of the sheet guide, wherein the sensor is mechanically coupled with all sheet conveyors and/or with the sheet guide.

3. Device according to claim 2, characterized in that the sheet guide is essentially constructed in the form of a disk or a wheel.

4. Device according to claim 2, characterized in that each sheet conveyor is essentially constructed as a two-arm swivel beam, which has a gripping element in the area of its two free ends, pointing outwards radially.

5. Device according to claim 4, characterized in that several of the sheet conveyors and the sheet guide are doubly provided and are located on the common axis, with mirror symmetry with respect to one another, in such a way that all sheet conveyors are placed between the two sheet guides, so that a front edge of a sheet can be gripped jointly, in its course parallel to the common axis of the sheet conveyors and the sheet guides, by two of the, all total, at least four sheet conveyors and two sheet guides.

6. Device according to claim 5, characterized in that the sensor is coupled, by guide links, with the majority of the sheet conveyors.

7. Device according to claim 6, characterized in that the sensor has at least one bearing arm, which carries at least one roller element, guided and rolling on a guide link.

8. Device for the placement of sheets for a printer, including at least one rotating drivable sheet conveyor, which is provided to accept or grip a front end of a sheet and to place the sheet on a stack of sheets after traversing a rotation path, and a sensor device to detect the attained stack height or the attained level, which has at least one sensor, which functions, simultaneously, as a holding-down element for the stack, which is lifted, mechanically controlled, from the stack, for the release of the stack, so as to place the next sheet on the stack characterized in that; several of these sensors, which are arranged, distributed, over the stack width, are provided, all of which are coupled mechanically with at least one sheet conveyor.

9. Device according to claim 8, characterized in that three sensors are provided, of which one is placed in the middle of the stack and the other two, at a distance to one and the other side of the middle sensor.

10. Device according to claim 8, characterized in that to detect the level position of at least one sensor, at least one sensor element is provided.

11. Device according to claim 10, characterized in that the sensor element is a light barrier, preferably a forked light barrier.

12. Device according to claim 10, characterized in that three marked level positions of the sensor can be detected by the sensor element.

13. Device according to claim 12, characterized in that the lifted position, the stack zero position, and the lowest stack position of the sensor can be detected.

14. Device according to claim 13, characterized in that the marked level positions are recognizable by a switch flag, coupled with the sensor.