GB2028773A - Conveying sheets - Google Patents

Abstract

Apparatus for changing the direction of flow of sheet material including a wedge-shaped receptacle 12 having one or more rotating paddle wheels 24, 26 positioned near the wide end thereof. Each of the blades of the paddle wheels is flexible and forms a helix angle with the shaft 28 supporting the paddle wheels for rotation thereabout. Rotation of the paddle wheels changes the direction of flow of the sheet material and positions the sheet material for duplexing and, additionally, corrects for any skewing of the sheet material. <IMAGE>

Description

SPECIFICATION Apparatus for changing the direction of flow of sheet material In the printing, copying and duplicating fields it is sometimes necessary to provide apparatus having duplex printing capabilities, that is, capacity to print or copy on both sides of a sheet of paper or other material. Such duplex printing apparatus imprints data on one side or face of a sheet material on its initial run through the apparatus, and imprints data on the opposite side of the sheet material upon a second run through the apparatus. Accordingly, such apparatus must have the capability of reversing the direction of flow of the sheet material prior to the second data imprinting operation.

One type of prior art apparatus of the aforedescribed type is disclosed by IBM Technicai Disclosure Bulletin, Volume 18, Number 1,June, 1975, Page 40, wherein a first pair of rollers of a turnover pocket force a sheet to be inverted in a first direction and against a plurality of stop fingers mounted on a shaft which is spring biased in an opposite direction. If the sheet enters the turnover pocket in skewed fashion, it engages one of the fingers and rotates the shaft and the plane of all of the fingers. When the sheet is totally inserted into the turnover pocket, the leading edge aligns in the plane of the stop fingers which deskews the sheet, and the spring bias drives the sheet's trailing edge (now its leading edge) into the nip of a second pair of rollers and out of the turnover pocket for duplexing.The described inverting and deskewing apparatus is relatively complex, requiring two pairs of rollers and a plurality of spring biased stop fingers.

It is an object of the present invention to provide apparatus for reversing the direction of flow of sheet material which can also provide deskewing or registration capabilities.

To this end, the invention provides an apparatus for changing the direction of sheet material and for deskewing the sheet material comprising a wedgeshaped receptacle having an open wide end and a closed narrow end, at least one paddle wheel mounted across said wide end of said receptacle, said at least one paddle wheel being characterized by a hub portion and a plurality of flexible blade members spaced around said hub portion, each of said blade members having an angular offset relative to the longitudinal axis of said hub portion, and means for rotating said at least one paddle wheel whereby sheet material is pulled in one direction and into said receptacle by the rotary action of said at least one paddle wheel and is pulled in an opposite direction and out of said receptacle in a deskewed orientation by the continued rotation of said at least one paddle wheel.

In a preferred embodiment, the apparatus includes a pair of rotating paddle wheels which are disposed within the opening between the top and bottom wall members of the wedge-shaped receptacle. The diameter of the paddle wheels is slightly larger than the opening between the top and bottom wall members, and each of the blades of the paddle wheels is flexible and forms a helix angle with the shaft member rotating the paddle wheels. A sheet member returning for duplexing enters the wedgeshaped receptacle along the top wall thereof. As the paddle wheels gain control of the sheet member they drive the sheet member toward the narrow end of the receptacle and to one side wall of the receptacle due to the helix action of the blades which give the sheet member a sideways component of direction toward one side of the receptacle.When the sheet member hits the end wall of the receptacle, which has a depth measured from the paddle wheels of slightly less than the length of the sheet member undergoing a direction change, the trailing edge of the sheet member drops and the sheet member is driven to the bottom wall of the receptacle by the rotating paddles which never lose contact with the sheet member. At this point, the paddle wheels drive the sheet member forward toward the wide end of the receptacle and against the one side wall of the receptacle whereby an edge of the sheet is aligned against the one side wall of the receptacle. Thus, one edge of the sheet member is aligned against a side wall of the receptacle thereby providing deskewing of the sheet should it enter the receptacle in a skewed fashion.

In order that the invention may be more readily understood, reference will now be made to the accompanying drawings, in which: Figure 1 is a partially cut away perspective view of an apparatus for changing the direction of flow of sheet material in accordance with the invention.

Figure 2 is a side sectional view of the apparatus of Figure 1.

Figure 3 is an isometric view of a component of the apparatus of Figure 1.

Figures 4a-4c illustrate in sequence the action of a rotating paddle wheel on moving sheet material.

Referring now to Figure 1, there is shown an apparatus for changing the direction of flow of sheet material which includes a wedge-shaped receptacle 12 which is wider at the left end than at the right end, as shown clearly in Figure 2. Receptacle 12 is comprised of top and bottom walls 14 and 16, respectively, sidewalls 18 and 20, respectively, and end wall 22. Receptacle 12, which can be made of sheet metal or other suitable materials, is wider, on the order of one to three inches wider, than the widest sheet material to be duplexed.

A pair of paddle wheels 24 and 26 are mounted on a shaft 28 which extends through, and is oriented perpendicular to, the sidewalls 18 and 20. The paddle wheels have a diameter slightly larger, for example, 1/8" larger than the height of the receptacle 12 at the point where shaft 28 passes thereto. Shaft 28 is driven in clockwise rotation by motor means (not shown) at a speed on the order of 450 revolutions per minute. Located near the wide end of receptacle 12 is a hinged timing gate 30 which can be lowered from the position shown to a position flush with bottom wall 16 by conventional means (not shown) upon receipt of a control signal.

Referring to Figure 3, each of the paddle wheels 24 and 26 is comprised of three blade members 32,34 and 36, which are equally spaced around a hub portion 38 which is received by shaft 28. The blade members are made of a flexible material such as polyurethane and are formed at a helix angle a ranging between 20 to about 50 and preferably from 25 to 35 along the axis of shaft 28 as described in more detail in United States Patent, 3,669,447. The blade members have a length to width ratio ranging from about 2:1 to 3::1 and preferably are about one half inch wide and about 1-1/4to 1-1/2 inches long and have a thickness ranging from about 0.050 inch to about 0.100 inch and preferably from about 0.065 inch to about 0.075 inch to obtain proper blade flexing when contact is made with the sheet material atthe blade tips.

In operation, a sheet member S returning from simplex printing for duplex printing is guided (by means not shown) such that it enters wedge-shaped receptacle 12 along the top wall 14 thereof (position 1) as shown in Figure 2. As the clockwise rotating paddle wheels 24 and 26 gain control of sheet member S they drive sheet member S toward the rear wall 22 of the receptacle 12. Due to the helix action of blade members 32, 34 and 36 the sheet member S is given a sideways component of motion towards side wall 18 as it traverses toward end wall 22.Since the distance from the paddle wheels 24 and 26 to the end wall 22 is slightly less (1/4" to 3/4" less, for example,) then the length of sheet member S, the leading edge of sheet member Swill eventually strike end wall 22 (position 2) at which time the trailing edge of sheet member S buckles slightly and is driven against the bottom wall 16 (position 3) by inertial forces and the continuing clockwise rotation of paddle wheels 24 and 26 which never lose contact with sheet member S. During such movement paddle wheels 24 and 26 continue to exert a sideways component of motion on sheet member S, driving it toward, and eventually flush with, sidewall 18. Thus, one side of the sheet member S is aligned against sidewall 18 thereby providing deskewing of the sheet member S should it enter the receptacle 12 in a skewed position.

Further rotation of paddle wheels 24 and 26 drives or pushes the sheet member S against the gate 30.

At the proper time the gate 30 drops to its position flush with bottom wall 16, and the paddle wheels 24 and 26 push the sheet member S between rollers 40 and 42 thereby sending it on its way to duplexing.

Referring now to Figures 4a - 4c, there is shown in sequence the movement imparted to sheet member S by one of the paddles 32,34 and 36, for example, paddle 32. Slightly skewed sheet member S is initially contacted by the outer tip of paddle 32 (Figure 4a). Due to the helix angle of paddle 32 with shaft 28 and the unique shape and thickness of the paddle, paddle 32 is caused to flex to the outside or to the left looking at the figures which imparts a leftward force on sheet member S thereby carrying sheet member S forward and to the left (Figure 4b) toward side wall 18. As the paddle 32 continues to rotate, the outside tip thereof moves out of control with sheet member S and the inner part of the paddle is placed in contact with sheet member S causing a forward force to be exerted on sheet member S in the direction in which the paddle wheels are being rotated.The inner part of the paddle does not flex to the same degree as the outer portion thereof by virtue of the fact that the outer portion commences to return to its original shape after being flexed against the sheet member thereby tending to impart a force against further flexing of the paddle in a sideways direction. As a result, the trailing portion of the paddle 32 serves to move sheet member S forward. Since the paddles 32,34 and 36 are continuously rotating and are acting on sheet member S, there is a continuous action pulling the sheet member S forward and to the left and eventually against side wall 18 (Figure 4c).

From the foregoing, it can be seen that a simplified structure is provided for changing the direction of sheet material and for correcting any skewing thereof whereby the sheet material is rendered ready for duplexing. The disclosed structure uses only rotating paddle wheels for that purpose and not sets of rollers and pluralities of spring biased stop fingers.

Also, the disclosed structure does not require the use of the auxilliary paper tray and hence full use of the auxilliary paper tray is maintained.

Although the invention has been described in terms of two paddle wheels each having three paddles, one paddle wheel or more than two paddle wheels could be utilized. Also, each paddle wheel can have less than three or more than three blades.

Also, to accommodate sheet material of different lengths, the position of the end wall 22 can be changed as by having end wall 22 frictionally mounted for movement along a track or similar guiding device.

Claims (5)

1. Apparatus for changing the direction of sheet material and for deskewing the sheet material comprising a wedge-shaped receptacle having an open wide end and a closed narrow end, at least one paddle wheel mounted across said wide end of said receptacle, said at least one paddle wheel being characterised by a hub portion and a plurality of flexible blade members spaced around said hub portion, each of said blade members having an angular offset relative to the longitudinal axis of said hub portion, and means for rotating said at least one paddle wheel whereby sheet material is pulled in one direction and into said receptacle by the rotary action of said at least one paddle wheel and is pulled in an opposite direction and out of said receptacle in a deskewed orientation by the continued rotation of said at least one paddle wheel.

2. Apparatus according to Claim 1, wherein said angular offset is between twenty degrees and fifty degrees.

3. Apparatus according to Claim 1 or 2, wherein said receptacle has a depth from the rotation point of said at least one paddle wheel to said closed narrow end which is greater than the length of said sheet material.

4. Apparatus according to Claim 1,2 or 3, wherein said blade members have a length to width ratio ranging from about 2:1 to about 3:1, and a thickness ranging between about 0.050 inch to about 0.100 inch.

5. Apparatus for changing the direction of sheet material and for correcting any skewing of the sheet material, constructed, arranged and adapted to operate substantially as herein before described with reference to the accompanying drawings.