Sheet Separator Control Apparatus

Abstract

Apparatus to control the operation of corner separator members operating to separate individual sheets from the top of the stack as they are depleted. A pair of sheet separator members positioned at the stack corners resist the movement of the sheets to force only the topmost sheets to buckle thereover and be fed therepast. The separator members, each mounted on an arm, move in a generally vertical path as the sheets are fed from the top of the stack. As the stack height decreases a biasing action enables pivotal movement of the separator member on the arm as contact is made with the stack edge near the bottom. A camming mechanism serves to raise the arm and separator member upwardly upon insertion of a new stack by mechanical actuation or an electrical signal.

Description

The present invention relates to sheet separator control apparatus for insuring continuous stripping of single sheets one at a time from a stack of sheets and, in particular, to controlling the movement of sheet separating members which enables the separation of the topmost sheet from a stack of sheets commonly used in duplicating machines and the like.

Sheet feeding is normally accomplished by a rotatable shaft equipped with feed rollers frictionally engaging the topmost sheet of a stack of sheets forcing the sheet forward past a separating element commonly referred to as a snubber. The snubber is usually positioned at the leading edge of the stack at or near the corners thereof so as to cause the corners of the topmost sheet to buckle and then snap over separating the topmost sheet from the rest of the stack as described, for example, in U. S. Pat. No. 3,476,381. Existing sheet separating devices have not been entirely satisfactory in the sense of moving the separating element relative to the stack of sheets being fed in the sense that a proper position must be maintained continuously during the sheet feeding operation irrespective of the stack height.

The present invention provides for continuous effective sheet separation by sheet separator control apparatus which is simple and low in cost yet provides for effective separation of individual sheets of different weights and stiffness characteristics without ripping or otherwise damaging the sheets.

It is therefore the primary object of this invention to improve separation of sheet material fed from a stack.

A further object of this invention is to improve the control of sheet separating devices capable of separating individual sheets from a stack used in duplicating machines or the like.

A further object of this invention is to control the movement of separating devices for separating individual sheets fed from the top of a stack of sheets as the stack is unloaded and then reloaded.

Further objects, features and advantages of the invention pertain to the particular arrangement in structure which may best be understood by the following detailed description of the invention which may be read in connection with the accompanying drawings wherein:

FIG. 1 is a plan view of sheet feeding apparatus incorporating sheet separating apparatus and sheet separator control apparatus according to the present invention;

FIG. 2 is an enlarged plan view of the sheet separating apparatus of the invention;

FIG. 3 is a side view of the corner sheet separating plate member;

FIG. 4 is an isometric view of the corner sheet separating plate member;

FIGS. 5( a) and 5( b) illustrate the sequential operation of the sheet separating apparatus during feeding of sheets having a relatively low rigidity or beam strength;

FIGS. 6(a) through 6(c) illustrate the operation of the sheet separating apparatus during feeding of sheets having a relatively high rigidity or beam strength;

FIGS. 7(a) and 7( b) are side views of the sheet separator control apparatus in its lowest and highest positions, respectively;

FIGS. 8( a) through 8( d) are enlarged views illustrating sequentially the relationship between the stack and the sheet separating apparatus at different positions of the sheet separator control apparatus.

Referring now to FIG. 1 there is shown sheet feeding apparatus incorporating sheet separating apparatus and sheet separator control apparatus of the present invention. The feeding apparatus comprises spaced plate members 10 and 12 which serve to support a stack of sheets to be fed one at a time, as for example, towards the processing stations of a copying machine. The plate members 10 and 12 are movable toward and away from each other to accommodate different sheet widths through a manually operated sheet adjusting mechanism 15. Sheet adjusting mechanism 15 includes a release member 17 which when depressed by an operator enables the plate members 10 and 12 to move towards and away to predetermined positions. These positions are accurately determined by the help of a pointer member 19 which is matched with indicator works 21 on the frame indicating different sheet widths. Plate members 10 and 12 are arranged with elongated members 23, 25, respectively, which have tooth portions engaging a fixed gear 27. By this arrangement when release member 17 is depressed, movement to the plate member 10 causes the gear 27 to rotate and impart an equal movement to plate 12.

In feeding sheets from a stack the topmost sheet in the stack is advanced forward, that is, in the direction of sheet separating assemblies 30 by rotating feed rollers 35. Feed rollers 35 are driven by a rotatable shaft and may be any suitable construction as, for example, described in copending application Ser. No. 838,907, filed July 3, 1969, entitled Sheet Retaining Apparatus. The feed rollers act upon the topmost sheet to drive the sheet forward over the second sheet in the stack. The movement of the topmost sheet therefore tends to advance the second sheet. The amount of movement depends upon the surface characteristics of the sheets. In order to insure separation of only the topmost sheet from the stack, the sheet separating assemblies are adapted to apply a restraining force to the topmost sheet as well as to the leading edge of the upper most sheets of the stack such that only the top sheet is able to buckle therepast. The sheet separating assemblies 30 are symmetrically arranged complementary to each other and it is believed necessary to describe the detail of only one of the assemblies.

Referring now to FIGS. 2-4, there is shown more clearly the sheet separating assembly which comprises a corner sheet separating plate member 40 which extends diagonally across the corner portion of the stack in overlying relationship therewith. Extending from the plate member 40 are elongated portions 42 and 44 which have openings 46 and 48 formed therein respectively. It will be noted that the opening 48 is longer than opening 46 for reasons which become more apparent hereinafter. Also extending from elongated portion 42 is a stop portion 49 for a purpose explained hereinafter. Plate member 40 is supported on a shaft member 51 received in openings 46 and 48. Shaft member 51 is secured to an arm member 53 which serves to raise and lower the sheet separating assemblies will be explained more fully hereinafter. Extending from the plate member 40 is a resilient portion 45 which is located to one side of the center line of the plate member and abuts against the shaft member 51. By this structure the sheet separating assembly is able to pivot or deflect as shown by the dashed line portions of FIG. 2 when a sheet having a high beam strength or rigidity is advanced. The sheet is buckled or snapped from under the plate member 40 as it is forced forward by the feed rolls thereby enabling a sheet even of relatively high rigidity or beam strength to be buckled past the plate member without tearing or otherwise damaging the sheet.

The operation of the sheet separating assembly may be best understood in connection with FIGS. 5 and 6. As shown in FIGS. 5(a) and 5(b) the sheet separating assembly is shown acting upon a stack of sheets with a relatively low beam strength or rigidity. In this case the top sheet buckles primarily on the outside edge at x because the beam strength of the sheet is not sufficient to deflect the sheet separating assembly and the sheet corner buckles past the assembly as shown in FIG. 5(b). FIGS. 6( a) through 6(c) show the sequence of operation in the case of a sheet with a relatively high beam strength or rigidity. As the top sheet is advanced buckles y and z are formed adjacent to the sheet separating assembly. Due to the relatively high force imparted to the assembly the plate member 40 pivots relative to shaft member 51 against the action of the finger portion 45 causing the elongated portion 44 to advance moving the plate member 40 relative to the stack corner. In this manner, the buckling of the sheet past the sheet separating assembly is facilitated. It will now be appreciated that the sheet separating apparatus is such that individual sheets may be separated from a stack irrespective of the beam strength thereof. In the past, stiff sheets would tear or otherwise be damaged by the separating plates.

SHEET SEPARATOR CONTROL APPARATUS

As sheets are fed from the top of the stack, the sheet separating assembly moves downwardly in a generally vertical path until such time as the stack is depleted at which time the assembly is raised for the insertion of a new stack. In order to accomplish this operation, a sheet separator control apparatus is utilized for effecting movement of the sheet separating assembly so as for it to remain substantially in continuous operative contact with the corner of the stack during the separating operation. Due to the fact that the path of plate member 40 deviates slightly from a position at right angles to the stack edge there would be a tendency for it to push against the edge of the stack as the stack is depleted but this is compensated for by the sheet separator control apparatus of the invention.

The sheet separator control apparatus 60 includes the arm member 53 which has a stop portion 65 and a weighted portion 67. A compression spring 69 is wound around shaft member 61 and has one end engaging stop portion 49 and the other end engaging stop portion 65. By this arrangement a biasing action is maintained on the plate member 40 to maintain a predetermined position of the plate member 40 to the corner of the stack during the separating operation. Arm member 53 is supported in a side plate 69 which is secured to each of the plate members 10 and 12. Plate member 69 is formed with openings 71, 73 which receive pin members 75, 77 extending from the arm member 53. It will be noted that the openings 71, 73 are elongated with a curved contour such that when the arm 53 is raised the pin members 75, 77 follow along the contour of the openings causing the sheet separating assembly to move in a substantially vertical path. To raise the sheet separating assembly upon insertion of a stack of sheets to be fed, a camming mechanism including an actuator member 81 serves to actuate a pivot member 83 which rocks a pivot member 85 thereby camming the arm member into a raised position. It will be appreciated that the actuator member 81 can be actuated automatically by an electrical or mechanical input in any suitable fashion as by solenoid actuation to raise the arm member. A coiled spring member 88 is connected to a pin 89 extending from the arm member and to the plate 69 to exert a force on the arm member in a downward direction thereby maintaining engagement of the arm member and sheet separating assembly with the top of the stack of sheets. Also weighted portion 67 on the arm member 53 serves to enhance the downward movement of the arm member. It will be appreciated that where the plate members 10 and 12 are arranged as sliding tray members relative to a frame that the portion 90 of the pivot member 83 may be contacted by a portion of the frame upon sliding the tray into a surrounding housing thereby causing the arm 53 and sheet separating assembly to raise above a stack of sheets placed on the plate members 10 and 12.

Referring now to FIGS. 8(a) through 8(d) the operation of the sheet separator control apparatus will be understood more easily. FIG. 8(a) shows the arm 53 in the highest position and FIG. 8(d) shows the arm member in position with the plate member 40 resting on the top of the stack of sheets to be fed. FIG. 8(c) shows most clearly the action of the plate member which pivots through an angle on shaft member 51 against the action of spring member 70 when the sheet stack is lowered to a predetermined level. When this occurs, there is a tendency for the plate member 40 to move in towards the stack of sheets. By virtue of the arrangement of the separator plate member on the lift arm member 53 a pivoting action is experienced enabling the sheets to be fed without interrupting the action of the sheet separating assembly to cause separation of the topmost sheet from the stack. FIG. 8(d) shows the arm member 53 in its lower most position with the stack of sheets depleted. It will be noted that a separator plate member 40 has pivoted back to its original position relative to the arm member 53 because there is no interference with the stack which has been depleted.

While the invention has been described with reference to the structure disclosed herein, it is not confined to the details set forth; and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims.

Claims

What is claimed is:

1. In a sheet-feeding apparatus for feeding a stack of sheets in which the topmost sheet of the stack is advanced past sheet separator means, the improvement comprising

sheet separator means positioned adjacent the front corners of the topmost sheet,

said sheet separator means including a sheet separator member overlying a corner area of the topmost sheet,

a support member pivotally supporting said sheet separator member adapted to move at substantially right angles to the stack and said sheet separator member in substantially a vertical direction as sheets are being fed,

said support member having a stop portion, extending therefrom,

spring bias means connected to said stop portion and said separator member to urge said separator member into a predetermined relationship therewith until such time as said separator member is carried against at least a partially depleted stack which causes pivotal movement of said sheet separator member downwardly against the action of said spring bias means so that the separator member is not urged against the edges of the stack,

said support member is connected to an arm member movably supported by a plate member, said plate member having elongated openings formed therein and receiving pins extending from said arm member and slidable therein, and camming means for raising said arm member along a predetermined path constrained by the movement of the pins in said elongated openings,

spring means connected to said arm member and the plate member to urge said arm member downwardly into contact with a stack to be fed.

2. Apparatus according to claim 1 wherein said camming means is responsive to mechanical actuating means.

3. Apparatus according to claim 1, wherein said camming means is responsive to an electrical signal.

4. Apparatus according to claim 1, wherein said arm member includes a weighted portion to facilitate lowering thereof.