Electrostatographic web feeding apparatus

Abstract

Electrostatographic web feeding apparatus disclosing details of a paper brake operating in conjunction with the paper sheet cutter for a paper roll or other web feed machine. The disclosed brake is actuated by a single electrical solenoid, and provides a positive paper stop at two spaced points on the paper substantially simultaneously and evenly, thereby preventing paper path skew. Two individual linear brake rods are pivotally connected to opposite ends of a teeter arm transverse the paper path. The solenoid is pivotally connected to the center to the teeter arm. The two brake rods are commonly driven but pivotable with respect to one another to automatically prevent one from applying any pressure to the paper until the other has also made contact, and then to automatically provide even and self adjusting brake pressure. Each has an independent return spring and is normally maintained slightly away from the web. This brake is disclosed operating in combination with feed means and a fixed curved perforated paper bubble forming member for smooth registered feeding into electrostatographic imaging means.

Description

The present invention relates to electrostatographic web feeding apparatus providing accurate sheet-feeding with web stopping and cutting, including an improved web cutter brake which operates very rapidly and evenly and prevents web skewing.

Previously published art relevant to the present invention includes particularly the "bubble chopper" disclosed in U.S. Pat. No. 3,639,053, issued Feb. 1, 1972, to Merton R. Spear, Jr. Reference may be had to that patent for a discussion of background and other relevant teachings, including an exemplary electrostatographic system. Other relevant published references include, for example U.S. Pat. No. 3,673,905, issued July 4, 1972, to Tateomi Kono, U.S. Reissue Pat. No. 27,720, issued Aug. 7, 1973, to R. C. Hanson, et al. (originally U.S. Pat. No. 3,416,861), and the references cited in these patents.

An exemplary embodiment of the present invention is shown and described hereinbelow as a part of an otherwise conventional exemplary xerographic apparatus and process. Accordingly, said xerographic apparatus and system need not be described in detail herein.

All of these references are hereby specifically incorporated by reference in this specification.

Further features and advantages of the present invention pertain to the particular apparatus and functions whereby the above-mentioned aspects of the invention are attained. Accordingly, the invention will be better understood by reference to the following description and to the drawings forming a part thereof, which are generally to scale, wherein:

FIG. 1 is a side view of an exemplary web feeding apparatus embodiment of the present invention, partially schematicised for clarity;

FIG. 2 is basically the same as FIG. 1, but showing the web brake and cutter actuated;

FIG. 3 is a top view of the embodiment of FIGS. 1 and 2, illustrating the perforated web bubble forming platen; and

FIG. 4 is a front view, transversely across the web path, of the embodiment of FIGS. 1-3, illustrating details of the web brake structure.

Referring now to the drawings, FIGS. 1 - 4, there is shown therein an exemplary web feeding apparatus 10 in accordance with the present invention. This apparatus 10 includes a paper brake 12 operating in conjunction with a paper cutter 14 for cutting a web of paper 16 from a paper roll 18 into individual image receiving sheets. The apparatus 10 also provides accurate sheet feeding of the paper 16 into an imaging means 20 in registration with an image thereon. The imaging means 20 shown here schematically is a portion of a conventional xerographic drum and associated transfer corotron for the transfer of a xerographic toner image to the paper 16 in a conventional manner. As noted above, many of the components of the apparatus 10 and the associated electrostatographic system are conventional, and, therefore, need not be described herein. Those components which are conventional are illustrated schematically for clarity.

Referring to FIG. 1 in particular, the path of the paper 16 will now be described in relation to the sequence or relative location of the disclosed apparatus 10 components acting on it as it moves downstream from the supply roll 18. It may be seen that the continuous web of paper 16 is continuously pulled from the supply roll 18 by a first web feed means 22, here comprising a continuously rotating conventional set of paper feeding friction drive wheels. This first feed means 22 is shown here directly adjacent the upstream end of a hump member 24 which extends into and deforms the path of the uncut web to form a web or hump. After passing over the hump member 24, the web feeds through the paper brake 12 located at the downstream end of a hump member 24. The web then passes through the closely adjacent (immediately downstream) conventional paper cutter 14, which is adapted to rapidly sever the entire web transverse the web direction of travel so as to cut the web into desired lengths of individual sheets of paper. The cutter 14 is followed downstream by a second conventional paper feeding means 26 for further feeding the paper on into the imaging means 20. The second web feed means 26 may comprise continuously operating conventional feed rollers operating at substantially the same web feeding speed as the first feed means 22, e.g., approximately 10 percent faster.

FIG. 2 illustrates both the paper cutter 14 and paper brake 12 being actuated to stop and then evenly cut the web 16. It will be appreciated that the operation of these two members is coordinated and synchronized with the position of the image on the imaging means 20, as described in the cited references. During this stop and cut operation the web is completely stopped by the paper brake 12, as will be discussed further herein, so that the web will not be moving as the paper cutter 14 is operating. This insures a smooth and even cut and prevents jamming or skewing of the web during the paper cutting operation. Here, the imaging means 20 is upstream.

To avoid interruption of the feeding, (with possible damage to the web in high speed feeding) there is provided here a novel means for forming a bulge or bubble of a controlled position and direction of bulging in the web of paper 16. This bubble is caused to expand smoothly in a direction normal the web path while the downstream edge of the web is stopped by the paper brake 12, so as to absorb and confine the additional length of paper being continuously fed downstream towards the paper brake 12 by the first feed means 22 during paper braking.

It has been found that uncontrolled formation of this bubble or buckle in the paper can result in multiple ripples and paper jams or wrinkling, particularly in high speed operations. The disclosed hump member 24 prevents this by providing positive pre-forming of the bubble and control over both the position and direction of the web bubble during both its expansion and contraction, for significantly improved reliability. It may be seen that the hump member 24 provides a continuous bubble or loop in the otherwise substantially planar path of the web 16 at all times, including the time periods in which the paper brake 12 is not engaging the web at all. Thus, when the paper brake 12 is actuated, the paper bubble is already pre-formed, i.e., initially partially buckled in the desired position and direction of buckling or bubbling. The web bubble will then continue to expand in the same shape and direction, as illustrated by the differences between FIGS. 1 and 2. It may be seen that the hump member 24 is a substantially continuous and smooth surfaced fixed platen extending slightly into the path of the web, having a curvature, as shown, of much less than 90.degree.. Thus, it does not present any significant obstruction or significant frictional resistance to the feeding of the web over its surface.

An important feature of the hump member 24 is that it is multiply apertured to prevent a vacuum from forming between it and the web 16. This allows the web 16 to very rapidly rise away from the hump member 24 into an expanded web bubble when the paper brake 12 is actuated. The rapid expansion of the web bubble requires the large area of the web over the hump member 24 to rapidly move away from its normal directly overlying position. By making the hump member as a thin, slightly curved, metal plate which is highly multiply perforated (to offer an insubstantial air flow resistance) this can be achieved. The hump member 24 does not offer any significant resistance to the rapid increase or expansion of the web bubble away from its supporting surface. Yet the web 16 is initially fully and continuously supported by the surface of the hump member 24.

These same advantages also apply to the desired rapid decrease in the bubble size when the web brake is released. The perforations prevent any air pressure trapping under the bubble as it is dropped downwardly.

During the expansion of the web bubble, means are preferably provided to limit its longitudinal extent at the upstream and downstream ends of the hump member 24. In the apparatus 10 this is provided at the upstream end of the feed means 22 and at the downstream end by a curved paper guide or deflector 28 directly adjacent the entrance to the paper brake 12.

If desired, conventional blower or fan means may be additionally provided for blowing a positive air pressure flow from underneath up through the perforated hump member 24 against the bottom of the web 16. This provides further insurance of the smooth, rapid, outward expansion of the web bubble away from the surface of the hump member 24 during paper braking.

It may be seen that with the above-described web bubble forming arrangement that no moving parts are required and the paper is fully supported in the normal (unbraked) paper path on a smooth surface. Further, the space above the hump member 24 is unrestricted so that the paper bubble can rise as far as necessary above the surface of the hump member 24 without restriction. With this arrangement the first feed means 22 and its feeding of the web smoothly from the supply roll 18 can be substantially unaffected by the stopping of the web downstream of the hump member 24 by the paper brake 12. Only the second feed means 26, which is located here downstream of the paper brake 12, and paper cutter 14, will be affected by the stopping of the web. This can be taken care of simply by allowing the wheels of the second feed means 26 to slip slightly during the brief time period between the time the paper brake 12 stops the web and the time the paper is severed by the cutter 14. As soon as the paper is cut it is free to continue its downstream movement by the second feed means 26. Continuous operation of the second feed means 26 is desirable even though some slipping occurs, in order to maintain tension on the web as it is being severed, which is desirable.

Considering now in particular the paper brake 12, the operation thereof is illustrated in the side view of FIG. 2 and the details thereof are more fully disclosed in the front or transverse web view of FIG. 4. The web brake 12 provides, upon actuation, a very rapid stopping of the web without skewing, tearing or buckling of the web. These have been problems with many prior paper brakes when used for rapidly stopping for cutting a segment of a rapidly moving web. The paper brake 12 automatically provides substantially simultaneous and even pressure stopping engagement with the web at two points spaced apart transversely on the web, thereby positively preventing web skewing from either the braking itself or from the operation of the paper cutter 14.

The paper brake 12, of course, is actuated in conjunction with the paper cutter 14, but its braking operation should be completed prior to the beginning of the cutting operation of the paper cutter 14. That is, the web is preferably fully stopped in the paper cutter 14 before the paper cutter begins to cut the paper. Also, the paper brake 12 is preferably closely adjacent the paper cutter. It is desirable that the web brake 12 engage the web only intermittently and as briefly as possible only during the operation of the paper cutter 14, so as to interfere as little as possible with the normal web feeding, and to require as small as possible a web bubble expansion over the hump member 24. The brake 12 is particularly suited for such rapid braking and release of the web.

The paper brake 12 is preferably driven by a single short stroke linearly operating commercially available electrical solenoid 30. The solenoid 30 is shown mounted to a fixed frame 32 with its operating rod or plunger stroke normal the plane of the web 16. The operating plunger of the solenoid 30 is pivotally connected to the center of a teeter arm 34, so that actuation of the solenoid 30 draws the teeter arm 34 upwardly towards the frame 32 and the web 16. However, the teeter arm 34 is free to rotate or teeter intermediately relative to the solenoid 30 about the pivotal inter-connection provided by pivotal connecting means 36, which may be a conventional pin connection.

The teeter arm 34 is an elongated bar extending transversely across a major portion of the web, and generally parallel thereto. It is preferably a thin plate set edgewise (perpendicular) to the web so as to form a strong, but light weight beam for transmitting the force of the solenoid 30 to its outer ends. It may be seen that these outer ends of the teeter arm 34 are each connected to the bottom ends of elongated vertically extending brake rods 38 and 40 respectively. These connections are also conventional pivotal pin connections. Both of the brake rods 38 and 40 are preferably thin cylindrical steel rods extending upwardly from the ends of the teeter arm 34 perpendicularly toward the web 16. They are preferably restrained or guided for purely linear reciprocal movement in this direction by a pair of fixed cylindrical slide guides 42, shown in the partially broken away section around the brake rod 40.

The brake rods 38 and 40 each have frictional brake pads 44 and 46, respectively, at their upper ends adapted to engage the bottom of the web 16 and also to force the web 16 upwardly against directly overlying fixed brake pads 48 and 50. Thus, upon actuation of the solenoid 30, one area of the web is rapidly caught and stopped between the brake pad 44 on the brake rod 38 and its mating fixed brake pad 48, and another quite separate area of the web is simultaneously caught and stopped between the brake pad 46 on the brake rod 40 and the mating fixed brake pad 50.

It may be seen by the above-described connection that the two brake rods 38 and 40, and the respective brake pads 44 and 46 thereon, are commonly or simultaneously driven by the connection to the teeter arm 34 by the solenoid 30 toward the web when the solenoid is actuated. However, the two brake rods are individually freely pivotable with respect to one another. Thus, if one moving brake pad 44 or 46 contacts the the paper before the other, the teeter arm rapidly pivots to bring the other brake pad into engagement with the paper. Thus, the paper brake 12 cannot stop the paper at one braking point prior to its being stopped at the other braking point. Further, the described pivotal mounting also insures that the braking force remains even between the two braking areas at all times, during both actuation and removal of the braking forces. The solenoid 30 cannot apply an uneven force between the two brake rods. Also, the two separate braking actions provided by the two brake rods are also automatically self-adjusting regardless of the initial spacing or adjustment of the brake pads relative to the web. Further, the described pivotal connections prevent any tortional or lateral forces from acting on the brake rods. Therefore, they can be reciprocally slidably mounted in the simple cylindrical bushings provided by the rod guides 42 without any danger of binding during operation.

The pivotal connection of each brake rod equidistantly on opposite sides of the pivotal connecting means 36 allows pivotal movement of the teeter arm relative to the web in direct response to uneven pressures between the brake pads 44 and 46. Thus, the teeter arm 34 cross-transmits and evenly balances these pressures while at the same time rapidly applying braking pressure to both brake pads through the common central upward movement of the same pivotal connecting means 36 by the solenoid 30.

Each brake rod 38 and 40 has a separate return spring 52 and 54, respectively, to normally urge and retain it away from the web 16 except when the solenoid 30 is actuated (energized). These are preferably sufficiently strong coil springs under pre-compression to rapidly inactivate the paper brake as soon as the electrical energization is removed from the solenoid 30. Mechanical spacing stops 56 and 58, which are independently screw adjustable, are provided as brake adjustments to limit the maximum extent of movement of the ends of the teeter arm 34 away from the web 16. This thereby determines the maximum spacing of the brake pads 44 and 46 out of contact with the web. By adjusting the stops 56 and 58, the brake rods 38 and 40 can be independently maintained only a short distance from the web. This means that only a very short stroke of the solenoid 30 is required to bring the brake pads into paper contact, for faster braking action upon actuation of the solenoid 30.

In conclusion, it may be seen that the above-described structure provides a very simple and rapid acting, yet effective web feeding system in which the paper may be stopped and cut without skewing, and with minimum interference to the continuous web feeding operation. It will be appreciated, in accordance with the teachings of the above and other references, that various of the components of the feeding apparatus 10 could be relocated up or downstream with respect to one another along the paper path and still achieve the same basic advantages and objectives. Various other modifications or improvements will be apparent to those skilled in the art. Although the exemplary embodiments described herein are presently considered to be preferred, the following claims are intended to cover all variations and modifications as fall within the true spirit and scope of the invention.

Claims

What is claimed is:

1. In electrostatographic web feeding apparatus for feeding downstream a web of image supporting material from a web supply to an imaging means for transfer of an image from said imaging means to said web in registration, including registered web cutter means for cutting said web into individual sheets, the improvement comprising:

first web feed means for feeding said web from said web supply into said cutter means;

said cutter means being located downstream from said first web feed means;

web brake means for rapidly and evenly stopping said web at said cutter means and preventing skewing of said web relative to said cutter means,

said web brake means providing, upon actuation, substantially simultaneous and automatically even pressure stopping engagement with said web at at least two spaced points transversely of said web,

said web brake means being actuated in conjunction with said cutter means;

bubble means associated with said brake means for formation of an expandable bubble of said web to prevent interruption of web feeding while said web is stopped by said web brake means; and

second web feed means for feeding said web downstream from said brake means and said cutter means; wherein said brake means comprises:

brake drive means;

an elongated teeter arm connected to said drive means and extending transverse the direction of movement of said web;

pivotal connecting means providing connection for movement by said drive means of said teeter arm toward said web, but free intermediately pivotable movement of said teeter arm relative to said web;

and at least two independent web engaging means, each including frictional web brake surfaces, respectively connected to said teeter arm on opposite sides of said pivotal connecting means for relative pivotal movement on said teeter arm relative to said web in response to uneven pressures on said web brake surfaces;

said web engaging means both being connected to said teeter arm for movement therewith toward said web by said brake drive means.

2. The apparatus of claim 1, wherein said brake drive means is a single linear drive means pivotably connected to said teeter arm intermediately thereof.

3. The apparatus of claim 1, wherein there are only two web engaging means, spaced substantially apart transverse said web, and wherein fixed guide means are provided for restricting the movement of said web engaging means to linear movement normal said web.

4. The apparatus of claim 1, further including return spring means urging and normally maintaining said web engaging means out of contact with said web.

5. The apparatus of claim 2, wherein said brake drive means is a single linear short stroke, electrical solenoid directly pivotally connected centrally to said teeter arm, and having a linear output movement normal said web.

6. The apparatus of claim 4, further including independently adjustable mechanical spacing means for setting the maximum spacing of said web engaging means a small distance away from said web.

7. The apparatus of claim 1, wherein said first and second web feed means both operate continuously and at substantially the same web feeding speed.

8. The apparatus of claim 1, wherein said bubble means is a substantially continuous smooth surfaced fixed hump member extending into the path of said web to continuously preform and maintain a small bubble in said web over said surface of said hump member, and

wherein said hump member is a thin, slightly curved, plate which is highly multiply perforated to offer insubstantial air flow resistance.