IMPROVED ACCORDION-FOLD ENVELOPE This invention relates to expandable envelopes, and more specifically to an envelope having accordion pleats of unequal breadths to provide improved envelope handling, for instance, in the preparation and processing of high- volume business mail by appropriate automatic equipment. This invention is particularly, pertinent to mail pieces containing relatively large thicknesses of inserts.

For example, such preparation can include high- speed withdrawal of envelopes from stacks in hoppers and conveying of the envelopes; and, such processing can include stuffing of envelopes with inserts in an inserting machine and further handling for eventual mailing.

Prior art, expandable, accordion-fold envelopes have equal-breadth pleats and often encounter difficulties in handling, particularly in high-speed equipment, as envelope edges are variously engaged and gripped for purposes of withdrawal from a stack, of holding in position, etc. The commonly used mechanical grippers or jaws engage the envelope near its fold edge or edges. Pleats of accordion-fold envelopes are generally disposed relative to one another depending on the degree of fill of the envelope and for other reasons. Hence, gripping of conventional expandable envelopes can result in tearing, damage, and dislocation of envelopes with consequent equipment malfunction and downtime.

Prior art expandable-envelope or file-folder structures that comprise accordion-fold pleats include those disclosed in U.S. Patents Nos. 3,414,185 (Young); 3,860,164 (Dworkin) ; 3,643,858 (Deckys) ; 4,175,478 (Tripler) ; 4,294,400 (Gendron) ; 4,401,257 (Benham) ; 4,557,715 (Robinson); and 5,292,300 (Bluemle) .

Young discloses an expansible center-seam envelope with accordion-fold legs of equal-width (side gusset panels 12,14).

Dworkin shows a bellows-type envelope which allows for expansion at the bottom of the envelope, the bottom being divided into two equal sections by fold 16.

Tripler provides an expansible gusset envelope. Side gusset sections 34 and 36 are of equal width.

Robinson shows a file folder having gussets. Gussets appear to be of equal width; see for instance in FIGS. 2 and 3 - gussets 24 and 26.

Bluemle discloses an envelope blank with side flaps 6,7 having a fold line 15 which folds inwardly.

Disposed on either side of fold line 15 are an inner folding section 8 and an outer folding section 9, both being of equal width.

The other patents referenced in the foregoing are also indicative of the art in expandable envelopes and they too disclose pleats with panels whose breadths are equal.

All references cited herein are incorporated by reference in their entirety.

In view of the foregoing, it is a feature of the present invention to provide an improved, expandable, accordion-fold envelope, in particular for high-speed and high-volume mail processing. Another feature is for an envelope for holding of relatively large and different thicknesses of insert materials so that in-process tearing, damage, and dislocation of envelopes with consequent equipment malfunction and downtime is avoided.

SUMMARY In accordance with principles of the present invention, an expandable envelope is provided with accordion-fold pleat panels of unequal breadths. Breadths of successive panels differ such that reliable engagement of an envelope by a gripper jaw device (for instance of a mail

processing machine) is facilitated in the region of the fold edge of the pleat having the largest breadth.

A preferred embodiment of the expandable envelope of the invention comprises a front portion, a back portion, an assembly flap, and a closure flap.

The back portion is comprised of two side flaps originating as side extensions of the front portion. The side flaps are folded in accordion-fold pleats along score lines (between the front portion and a side flap) and have their overlapping ends attached to one another to thusly form the back portion and to close two opposite sides of the envelope.

The assembly and closure flaps originate as upper and lower extensions of the front portion. These flaps are folded along score lines (between the front portion and the respective flap) . The envelope is fully formed by attachment of the assembly flap to the back portion which closes the third side. After the envelope is filled or stuffed with inserts, the fourth side of the envelope is closed by the closure flap and by attachment thereof to the back portion.

The expandable envelope of the invention comprises means for offering unobstructed access for a gripper jaw device to a pleat panel for reliably gripping the panel in the region of the fold-edge without danger of grabbing, tearing, or otherwise damaging the envelope regardless of degree of fill.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference numerals refer to like parts throughout different views. The drawings are

schematic and not necessarily to scale, emphasis instead being placed upon illustrating principles of the invention.

FIG. 1 is a schematic, perspective view of an embodiment of the envelope according to principles of this invention;

FIG. 2 is a schematic, plan view of a blank for forming of the envelope illustrated in FIG. l;

FIG. 3 is a schematic, fragmental side view of a portion of a gripper jaw device gripping the envelope of FIG. 1; and,

FIG. 3A is a schematic, fragmental side view of a portion of a gripper jaw device (as shown in FIG. 3) gripping an envelope of prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2 of the drawings, an envelope 10 and a blank 11 (for forming the envelope) according to the invention are schematically shown. Envelope 10 comprises a planar front portion 12, a planar back portion 14 comprised of two side flaps 15, an assembly flap 16, and a closure flap 18. Disposed between front portion 12 and each side flap 15 (respectively back portion 14) is an accordion-fold pleat 20. Each pleat 20 comprises a first panel 22 and a second panel 24 hingedly coupled to one another along common pleat-edge 26. First panel 22 is hingedly connected to front portion 12 along a fold-edge 28. Second panel 24 is hingedly connected to a side flap 15 of back portion 14 along a hinge-edge 30.

Flaps 16 and 18 are scored along hinge lines 32 (in relation to front portion 12) to facilitate orderly bendability and to provide for different envelope-content thicknesses. Assembly flap 16 is generally closed and sealed to back portion 14. Closure flap 18 remains open in readiness for stuffing of the envelope with inserts. Flap

18 is closed and adhesively attached (sealed) to back portion 14 prior to mailing.

As can be seen from the drawings, FIGS. 1 and 2, envelope 10 is formed from blank 11 by appropriately folding accordion-fold pleats 20 along prescored lines, by bending over and joining side flaps 15 to form back portion 14, and by bending over of assembly flap 16 and attaching it to back portion 14.

As can be further seen from FIGS. 1 and 2, accordion-fold pleats 20 each comprise two pleat panels, a first panel 22 and a second panel 24. The combination of panels 22 and 24 is characterized by unequal breadths Bl and B2, respectively (see FIG. 2). These unequal breadths ensure that processing and handling of envelopes proceed reliably without tearing, dislocation, or other damage, particularly in high-speed mailing machines, as envelope edges and adjoining surfaces are variously engaged and gripped by gripper jaw devices or the like.

Referring now to FIG. 3, there is shown a fragmental side view of an envelope 10 held in a commonly used type of gripper jaw device 34. As shown, gripper jaw device 34 includes a gripper 36 and a jaw 38 between which a region in the vicinity of fold-edge 28 (of envelope 10) is gripped. It will be clear from this depiction that engagement of only the first panel 22 occurs, regardless of whether the envelope is empty, or partially, or fully stuffed. The smaller breadth of panel 24 allows ample unobstructed access for gripper 36 to panel 22.

In direct comparison, a conventional prior art envelope 40 with equal pleat panel breadths is schematically shown in FIG. 3A. Envelope 40 is held in the same gripper jaw device 34 as shown in FIG. 3. Clearly, the envelope can be gripped across the entire pleated side when the envelope is empty or only minimally expanded. However, when the envelope 40 is even moderately expanded, as shown here.

gripper 36 may or may not engage the upper portion of the pleat, may tear the upper portion of the pleat (and/or the edge thereof) , the envelope may be pierced by the gripper and may hang up upon disengagement, etc. Also, while envelope 40 is initially gripped (while empty) across both pleat portions in an inserting machine, as its accordion- fold pleat expands during stuffing with inserts, especially the upper pleat portion is liable to be torn and severely damaged. The expansion capacity of prior art envelope 40 is therefore severely limited.

As opposed to that, envelope 10 (FIG. 3) of the present invention, having unequal pleat panels 22,24 with unequal breadths, offers unobstructed access for gripper 36 to a portion of the outer surface 42 of first panel 22 in the vicinity of fold-edge 28. In other words, a spatial region above a portion of surface 42 (near fold-edge 28) remains unobstructed so that gripper 36 can be moved to and away from engagement with panel 22.

The unobstructed portion of outer surface 42 varies in breadth depending upon the degree of expansion of envelope 10. For instance, when unexpanded (with pleat 20 completely folded) , the breadth or width of the unobstructed portion of the outer surface 42 is equal to the difference between the breadths of the first and second panels 22,24 (respective breadths B1,B2) . This difference, therefore, represents the minimum breadth or width of the unobstructed portion of outer surface 42. The unobstructed portion of outer surface 42 increases in breadth with increasing expansion of the envelope 10 (as it is filled) . It has been found that useful differences between the breadths Bl and B2 range upwardly from slightly less than one tenth of an inch, a preferred difference being about three-eighths of an inch and larger. For example, an envelope 10 for insertion of 8.5 x 11 inch inserts and with an expansion capability of up to 1 inch has the following

preferred dimensions, as follows: 12.63 inches long by 9.5 inches wide; first panel breadth Bl equals 0.688 inches and second panel breadth B2 equals 0.312 inches.

While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications in form and details may be made therein without departing from the spirit and scope of the invention.