Abstract:
A modular envelope feed mechanism which may be used with a cut sheet feeder attachment for high speed printers or the like is disclosed. Envelopes are more reliably fed and separated because they are urged toward a pair of separators at the separation station with uniform force by a pressure plate containing a pivotable member provided with resilient pads positioned in alignment with the separators.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     U.S. patent application Ser. No. 453,023, filed concurrently herewith, having J. L. Huerta as inventor and commonly assigned. 
     DESCRIPTION 
     1. Technical Field 
     This invention relates to document feeding to high speed printers or the like more particularly it relates to improved apparatus for feeding envelopes to a high speed printer. 
     2. Background Art 
     Envelope handling apparatus is known in the prior art. The IBM 6640 Document Printer, for example, in addition to cut sheet feed and delivery includes an envelope handler capability. Another technique for handling envelopes in addition to cut sheets is taught in copending commonly assigned U.S. patent application Ser. No. 219,684 filed Dec. 24, 1980 having R. E. Hunt et al as inventors. Hoppers having a rear wall urged toward the document separation station are known, for example, U.S. Pat. No. 3,572,691. 
     U.S. Pat. No. 4,078,672 to Crepaldi et al teaches a slanted support urging items to be fed to the feed station. The angle of inclination is stated to be between 105° and 110° from the base of the feed tray. 
     DISCLOSURE OF THE INVENTION 
     Envelope feeding using the present invention is particularly enhanced as a result of the improved spring biased pressure plate. The pressure plate is used as the movable rear wall of the hopper and is urged forward as the envelope stack decreases in size. The pressure plate includes a pivotable plate portion with pads of resilient material. The pressure plate assembly is slanted at an angle 125° from the horizontal, measured from the feed station toward the rear of the hopper. This slant causes the envelope stack to be presented at the picking station in a pre-shingled state. The frontmost envelopes are shingled using roll wave picker separators and, after being properly aligned, are fed to the print station. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Referring now to the drawings wherein a preferred embodiment of the invention is illustrated, and where in like reference numerals are used throughout to designate like parts: 
     FIG. 1 is a perspective view of the envelope handling apparatus of the present invention. 
     FIG. 2 is a more detailed view of the means for controlling pressure plate 70 (FIG. 1) position. 
     FIG. 3 is a partial cross-sectional view of the envelope feed station. 
     FIG. 4 is a close-up view of one side of the alignment/restraining station. 
     FIG. 5 is a timing chart. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Refer now to FIG. 1. The envelope handling device of the present invention is indicated generally at 2, placed on top of a cut sheet handler indicated in phantom at 4 so that each may supply documents to a common path to platen 6 of the printer, not shown. 
     Envelope device 2 includes a hopper holding a stack 8 of envelopes comprised of base 10, fixed rear wall 12 and slotted side walls 14 and 16. Side wall 14 has slots 18 and 20 for purposes which will become clear as the description proceeds. Similarly, side wall 16 has parallel slots 22 and 24 which are aligned with those in side wall 14. Shaft 30 is rotatably mounted in side walls 14 and 16. Fixedly mounted on shaft 30 for rotation therewith are shingler rollers 32 and 34 of the ferris wheel type. A DC motor (not shown) is provided for driving shaft 30. 
     Also mounted across envelope handling device 2 in side walls 14 and 16 is rod 40. Rotatably secured to rod 40 is idler roller 42. Roller 42 is provided for constraining envelope stack 8 and enhances the concavity of the foremost envelope in the stack when it is being shingled forward. A shaft 48 is rotatably mounted downstream of rod 40 in side walls 14 and 16. Feed rollers 52 and 54, fixedly mounted on shaft 48, are driven through belt and pulley linkage (not shown) by platen 6. 
     The actual size of the envelope storage area within envelope handling device 2 is adjustable in accordance with the width and depth of the envelope stack 8 to be fed. Storage area width is adjustable by means of side guide 60. Lever 62 which is provided for releasing and locking the position of side guide 60 will be discussed in detail having reference to FIG. 3. Side guide 60 is slidably mounted on shaft 30 and rod 40. 
     Self-adjusting, movable pressure plate 70 which supports the rear of stack 8 is inclined at 55° C. to the horizontal base 10, measured from the direction of rear wall 12, of envelope handling device 2. This position enhances the separation of the foremost envelopes prior to the beginning of the mechanical separation cycle because some of the envelopes are already separated. Maintaining stack 8 at such an angle also magnifies the action of separation by providing more discrimination between the first and second envelope. 
     Pressure plate 70 includes four studs, two on either side, 72 and 74 on the left and 76 and 78 on the right, upon which are mounted four rollers having soft rolling surfaces. Rollers 80 and 82 are on studs 72 and 74; rollers 84 and 86, on studs 76 and 78. Studs 72, 74, 76 and 78 extend through the four parallel slots, 18, 20, 22 and 24, located in envelope device side walls 14 and 16, respectively. 
     Each of studs 72 and 76 is additionally provided with two cable connector clips for anchoring cables used to control the position of pressure plate 70 as it is urged in the direction of arrow 88. Stud 72 has clips 90 and 92 while stud 76 has attached thereto clips 94 and 96. Cable 98 is connected to clips 92 and 94 over pulley 100 mounted on side wall 14. Cable 102 is connected to clips 90 and 96 over pulley 104 mounted on side wall 16. Cables 98 and 102 are trained over a system of pulleys, which with appropriate spring means are provided for urging pressure plate 70 toward separator shingler rollers 32 and 34. This structure will be described having reference to FIG. 2. 
     Pressure plate 70 includes an opening 110, corresponding in size and shape, for accommodating pivot plate 114 which is pivotally mounted by means of brackets 116 and 118 to pressure plate 70. Pivot plate 114 moves about an axis 121 through the center of rod 120. Opening 110 and pivot plate 114 located therein are positioned within pressure plate 70 so as to align pivot plate 114 with separator shingler rollers 32 and 34. In particular, resilient pads 124 and 126, located at either end of pivot plate 114, are aligned with shingler rollers 32 and 34, respectively. 
     Positioned directly beneath feed rollers 52 and 54 are back-up rollers 130 and 134. Back-up rollers 130 and 134 are rotatably mounted on studs 136 and 138, respectively, located at either end of bracket 140. Made integral with bracket 140, at either end thereof adjacent back-up rollers 130 and 134, are two sawtooth restraint edges 144 and 146. 
     Two micro-switches 150 and 152 for aligning and sensing the leading edge of an envelope from stack 8 are provided in appropriately shaped openings 156 and 158 in base 10. Openings 156 and 158 accommodate the micro-switches 150 and 152 which perform a dual function which will be described in greater detail having reference to FIG. 5, as well as sawtooth restraining edges 144 and 146, and back-up rollers 130 and 134. The entire restraint alignment function which occurs in the envelope path at a position beneath feed rollers 52 and 54 is more fully described and claimed in co-pending, commonly assigned, U.S. patent application Ser. No. 453,023. 
     FIG. 2 shows in more detail how pressure plate 70 is urged toward the envelope separation station with a non-skewed, bind-free, parallel motion. As above noted, stud 72 is provided with clips 90 and 92. Likewise, stud 76 has clips 94 and 96 attached. The system of pulleys over which cables 98 and 102 are trained additionally includes pulleys 170 and 172 mounted to member 174 and pulleys 176 and 178 mounted to member 180. Members 174 and 180 are connected to side walls 14 and 16, respectively. 
     Cable 98 is attached in parallel to a constant force spring 182, wound on spool 184, and to an extension spring 186. The other end of spring 186 is attached to side wall 14. The load of the constant force spring 182 is much greater than that of the extension spring 186. The load of pressure plate 70 is permitted to decrease as plate 70 moves toward separator shingle wheels 32 and 34 so that there is a substantially constant load between the separator rollers and stack 8 of envelopes. 
     The entire pressure plate 70 is urged toward the separator rollers because of the equal force exerted in studs 72 and 76 by the cable/pulley spring system just described. Since separator rollers 32 and 34 are not centered with respect to pressure plate 70, the force exerted against the separator rollers would not be equal. Pivotable plate 114 overcomes this problem. The forward urging force exerted on pressure plate 70 is transmitted through the pivot rod 120 centered in plate 114. In this way, resilient pads 124 and 126 urge envelope stack 8 with substantially equal force against separator rollers 32 and 34, respectively. 
     Locking lever 190 is provided to latch pressure plate 70 in its rearmost position. Stud 76 also serves as a detent member for cooperation with locking lever 190. The position shown at 190 is the locked position when pressure plate 70 is in its rearmost position. When pressure plate 70 is moved rearwardly, stud 76 momentarily cams lever 190 into the position shown in phantom at 192 to bring stud 76 under locking lever 190. The pressure plate is released by moving lever 190 into position 192 momentarily. 
     FIG. 2 also shows in more detail the adjustable side restraint 60 for envelope stack 8 (FIG. 1). Side plate 60 is slidably mounted on shaft 30 and rod 40. Lever 62 is provided to lock side plate 60 in a given location corresponding to a particular envelope width. Lever 62 is slidably mounted on shaft 30 and is pivotable about point 66 so that when the top of lever 62 is pinched leftwardly, the bottom portion 64 is released from engagement with the roughened surface of rod 40. Lever 62 has integral fingers that spring load the top of the lever to the right to provide the locking action. 
     Reliable separation and feed of envelopes in a stack 8 (FIG. 1) is enhanced by the improved pressure plate of the present invention, as will be apparent from the description of FIG. 4. FIG. 3 is a cross-sectional view through envelope apparatus 2 of FIG. 1. As pressure plate 70 is urged toward the separator shingle roller 32 in the direction of arrow 88, resilient pad 124 is illustrated in alignment with separator roller 32. The foremost envelopes in stack 8 have been shingled in the view. When the foremost envelope reaches the mid point of feed roller 52, it comes in contact with and actuates micro-switch lever 150 and closes the switch (FIGS. 1 and 4). At that point in the feed cycle, bracket 140 (FIGS. 1 and 4) having stud 136 with back-up roller 130 attached thereto moves in the upward direction of arrow 170 to clamp the foremost envelope between feed roller 52 and its back-up 130. The idler roller 42 on rod 40 functions to constrain envelope stack 8 and helps give the foremost envelope the concave form it assumes as it is shingled by shingler/separator roller 32. 
     FIG. 4 is a close-up view of the side of the alignment restraint station beneath feed roller 50 in FIG. 1. Bracket 140 is a unitary structure including the studs holding back-up rollers 130 and 134 (seen in FIG. 1) and at either end the sawtooth restraint edges 144 and 146 (seen in FIG. 1) and envelope lifter portions 160 and 162 (seen in FIG. 1). Means, not shown, are provided for lifting bracket 140 and its associated portions just mentioned above the plane of hopper base 10 so that once an envelope separated from stack 8 (FIGS. 1 and 3) makes micro-switch 150 and its corresponding switch at the other end (shown in FIG. 1) the bracket 140 is raised so that lifter portion 160 enables the envelope to be fed over the projecting lever 150 of the micro-switch. 
     The operating environment of the present invention may be readily understood in connection with the following description. The timing diagram of an envelope feed cycle will be described having reference to FIG. 5. At time t1 a using system feed signal request goes down. Simultaneously, a voltage for energizing the motor to drive shaft 30 with which the shingler separator wheels rotate goes up. The index signal for platen 6 of the using printer turns on platen index at the same time. The shingler motor voltage goes down when the envelope handler of the present invention senses that an envelope is properly aligned at the sense position and feed station, that is the point in time when sensor micro-switches 150 and 152 so indicate. At the same point in time, t2, the signal to raise bracket 140 having back-up rollers 130 and 134 attached thereto occurs. After a short delay, the sense position signal goes down at time t3. Following a delay of about 400 miliseconds, at time t4, the platen index signal comes up to line feed rollers 52 and 54 to transport an envelope through the feed station. The second delay is necessitated to allow bracket 140 to complete its upward travel into the feed path. At time t5 the signal for raising bracket 14 containing back-up rollers 130 and 134 goes down. The interval between time t4 and t5 is chosen to allow an envelope to completely clear the feed station of the apparatus of the invention and to enter the transport path of the using printer. 
     The present invention provides an envelope handling capability for use with high speed printers such as those used in word processing systems or the like. While with appropriate modifications, the device of the invention may be used directly with the printer, it is illustrated as being used in conjunction with a cut sheet handling device connected to the printer so that the user may avoid switching document handling devices in the midst of a job. 
     While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that the abovementioned modification and various other changes in form and detail may be made without departing from the spirit and scope of the invention.