MAILING ENVELOPES

Abstract: A mailing envelope has a front (1), a back flap (4) joined at a bottom fold line (5) to the front, side flaps (6) inwardly folded and secured to the back flap, and a top flap (3). So that the envelope is suitable for use in a very wide range of mailing machines:- (a) the respective side edges (8) of the top flap (3) extend at 65 - 75° to the top fold line for a perpendicular distance of at least 5 mm from the top fold line, (b) the side flaps (6) have top shoulders (10) which each extend away from the side fold line (7) at 10 - 20° to the top fold line (2) for a perpendicular distance of at least 18 mm, (c) the throat depth is at least 20 mm for a distance of at least 35 mm on each side of the centre of the top fold line (2), and (d) said top shoulders (10) intersect the upper edge (11-13) of the back flap (4) at a perpendicular distance in the range 4 - 15 mm from the top fold (2), and at this intersection (14) (i) the upper edge (13) of the back flap is at ± 10° to the top fold line (2), and (ii) the radius of curvature of the upper edge (13) is not less than 20 mm.

Description: This invention relates to mailing envelopes. The invention seeks to provide a mailing envelope which is suitable for use with all, or all the most used, automatic mailing machines at present available, at least those machines available in the United Kingdom. The envelopes are thus intended to be suitable for automatic mailing machines which insert sheets into envelopes and in some cases may also be suitable for other machines, which handle envelopes automatically, e.g. laser printers which print addresses on envelopes to be used in a mailing machine. A mailing envelope is conventionally formed from a single piece of paper and has a front, a back flap, side flaps inwardly folded between the back flap and the front and glued to the back flap, and a top flap which after insertion of material into the envelope is folded over and adhesively secured to the back flap. Automatic mailing machines, in particular automatic envelope insertion machines, receive a stack of envelopes with the top flap folded over, and perform the operations of opening the top flap, inserting the desired material into the envelope and closing the top flap. The most important suppliers of such envelope insertion machines at present include Pitney Bowes, Roneo Noepost, Boewe, Kern and Bradma. The manufacturers of each of these machines makes a different set of requirements for the shape of the envelope which can be used with their machine. We have now found that an envelope can be designed which is suitable for use with all these machines. The envelope of the invention does not necessarily meet the stated requirements of all the manufacturers of envelope insertion machines. Two regions of the envelope are of special importance. These are the shape of the various parts of the envelope around the upper corners of the front of the envelope and secondly the throat depth, i.e. the distance of the upper edge of the back flap from the upper edge of the front, called below the top fold line. According to the present invention there is provided a mailing envelope having a front, a back flap joined at a bottom fold line to the front, side flaps joined at side fold lines to the respective side edges of the front and inwardly folded and adhesively secured to the back flap and a top flap joined at a top fold line to the front, wherein (a) the respective side edges of the top flap adjacent the top fold line extend at an angle in the range 65 - 75°, preferably 68 - 72°, to the top fold line for a perpendicular distance of at least 5 mm from the top fold line, (b) the side flaps have top shoulders which meet the side fold lines at their junctions with the top fold line and adjacent said junctions extend away from the side fold line at an angle in the range 10 - 20°, preferably 16 - 20°, to the top fold line for a perpendicular distance of at least 18 mm, preferably at least 19 mm, from the respective side fold line, (c) the throat depth (i.e. the distance of the upper edge of the back flap from the top fold line), is at least 20 mm for a distance of at least 35 mm on each side of the centre of the top fold line, and (d) said top shoulders of the side flaps intersect the upper edge of the back flap at intersection points which in each case are at a perpendicular distance in the range 4 - 15 mm, preferably 8 -12 mm, from the top fold, and at the intersection point (i) the upper edge of the back flap is at an angle in the range ± 10°, preferably ± 5°, to the top fold line (ii) the radius of curvature of the upper edge of the back flap is not less than 20 mm. Preferably at the intersection point of the top shoulder of the side flap with the upper edge of the back flap, the upper edge of the back flap is straight. Preferably also this intersection point is at a straight portion of the top shoulder of the side flap. The upper edge of the back flap preferably has a lowermost central region, which provides the throat depth mentioned above, and side regions at which said intersection points with the top shoulders of the side flaps lie. This centre region is joined to each side region by an inclined portion which is preferably at an angle of not greater than 30°, more preferably not greater than 18°, to the top fold line. At the intersection point of the upper edge of the back flap and the top shoulder of the side flap, the intersection angle, i.e. the angle between these edges at the intersection point, is preferably in the range 5 - 20°. The invention also relates to the use of the envelope described above in automatic envelope insertion machines and to the method of insertion of mailing material into such envelopes using such machines. One embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a view of the back of the mailing envelope embodying the invention with the top flap opened, and Fig. 2 is a partial view of the cut but unfolded sheet from which the envelope of Fig. 1 is formed, showing the fold lines. It will be understood by the expert in this field that the overall width and height of the envelope, i.e. the width and height of the front, can be extensively varied, without alteration of the significant features of the envelope here illustrated as an example. The mailing envelope shown in Figs. 1 and 2 is formed of cut and folded paper and has a front 1 joined at a fold line 2 to a top flap 3 which, in conventional manner, has an area of adhesive (not shown). The envelope also has a back flap 4 joined at a bottom fold line 5 to the front 1 and at each side a side flap 6 joined at a side fold 7 to the front 1. As seen in Fig. 1, the folded in side flaps 6 underlie the edge regions of the back flap 4, and in a conventional manner at this area of overlap glue is applied to join these parts. Certain dimensions and angles can be read from Figs. 1 and 2. These and the other dimensions and angles mentioned below are the most preferred features of the envelope of the invention. From the junction of the side fold 7 with the top fold 2 (this junction will be called the top corner below), the top flap 3 has side edges having two regions 8,9. The region 8 adjacent the top corner extends at an angle of 70° to the top fold 2 for a perpendicular distance of 8 mm from the top fold 2. The portion 9 extends at 52° to the top fold 2. From the top corner, the top shoulder 10 of the side fold extends at an angle of 72° to the side fold 7, i.e. 18° to the top fold 2, for a perpendicular distance of approximately 34 mm from the side fold 7. This top shoulder 10 of the side flap 6 is straight, except that at its inner end remote from the side fold 7 it is rounded. The back flap has a top edge which has a centre region 11 parallel to the top fold 2 and spaced 20 mm from the top fold in the folded condition of the envelope. The width of this centre portion is determined by the overall width of the envelope, but is at least 70 mm, i.e. at least 35 mm on each side of the centre line of the envelope perpendicular to the top fold 2. This provides the necessary throat depth and width of the envelope. Inclined regions 12 of the top edge of the back flap 4 join this centre region 11 to side regions 13 which are also parallel to the top fold 2 and spaced 10 mm from the top fold 2. The inclined regions 12 are at an angle of 14° to the top fold 2. The width of the side regions 13 is approximately 19 mm, and it is at these straight side regions 13 that the back flap 4 intersects the shoulder 10 of the side flap 6. At this intersection point 14, therefore, the angle of intersection of the shoulder 10 with the region 13 is 18°. This relatively shallow angle is desirable, in combination with the location of this intersection point, in order to avoid excessive "stand up" of the top edge of the back flap above the shoulder of the side flap, if the folding of the envelope is somewhat inaccurate. The illustrated envelope has been found to be suitable for all the most used automatic envelope insertion machines available in the United Kingdom. Of course, with the wide variety of such machines available in the world, envelopes of the invention will not in general fit all such machines, but the invention provides a range of highly versatile envelopes.

Claims: A mailing envelope having a front (1), a back flap (4) joined at a bottom fold line (5) to the front, side flaps (6) joined at side fold lines (7) to the respective side edges of the front and inwardly folded and adhesively secured to the back flap and a top flap (3) joined at a top fold line (2) to the front, wherein (a) the respective side edges (8) of the top flap (3) adjacent the top fold line (2) extend at an angle in the range 65 - 75° to the top fold line for a perpendicular distance of at least 5 mm from the top fold line, (b) the side flaps (6) have top shoulders (10) which meet the side fold lines (7) at their junctions with the top fold line and adjacent said junctions extend away from the side fold line at an angle in the range 10 - 20° to the top fold line (2) for a perpendicular distance of at least 18 mm from the respective side fold line, (c) the throat depth is at least 20 mm for a distance of at least 35 mm on each side of the centre of the top fold line (2), and (d) said top shoulders (10) of the side flaps (6) intersect the upper edge (11-13) of the back flap (4) at intersection points (14) which in each case are at a perpendicular distance in the range 4 - 15 mm from the top fold (2), and at the intersection point (14) (i) the upper edge (13) of the back flap is at an angle in the range ± 10° to the top fold line (2), and (ii) the radius of curvature of the upper edge (13) of the back flap is not less than 20 mm. An envelope according to claim 1 wherein at the intersection point (14) of the top shoulder (10) of the side flap with the upper edge (11-13) of the back flap, the upper edge of the back flap is straight. An envelope according to claim 1 or claim 2 wherein at the intersection point (14) of the top shoulder (10) of the side flap with the upper edge of the back flap, the top shoulder (10) of the side flap is straight. An envelope according to any one of claims 1 to 3 wherein the upper edge of the back flap has a lowermost central region (11), which provides the said throat depth of at least 20 mm, and side regions (13) at which said intersection points (14) with the top shoulders (10) of the side flaps lie, said centre region (11) being joined to each side region (13) by an inclined portion (12). An envelope according to claim 4 wherein said inclined portions (12) are at an angle of not greater than 30° to the top fold line (2). An envelope according to any one of the preceding claims wherein at the intersection point (14) of the upper edge (11-13) of the back flap and the top shoulder (10) of the side flap, the intersection angle, is preferably in the range 5 - 20°. An envelope according to any one of claims 1 to 6 wherein the respective side edges (8) of the top flap (3) adjacent the top fold line extend at an angle in the range 68 - 72° to the top fold line for a perpendicular distance of at least 5 mm from the top fold line. An envelope according to any one of claims 1 to 7 wherein the top shoulders (10) extend away from the side fold lines at an angle in the range 16 - 20° to. the top fold line for a perpendicular distance of at least 18 mm. An envelope according to any one of claims 1 to 8 wherein said intersection points (14) in each case are at a perpendicular distance in the range 8 - 12 mm from the top fold. An envelope according to any one of claims 1 to 9 wherein at each said intersection point (14) the upper edge (13) of the back flap is at an angle in the range ± 5° to the top fold line. Use of an envelope according to any one of claims 1 to 10 in an automatic envelope insertion machine.

Inventors: BADRICK, GRAHAM EDWARD, MARTIN, ROBERT WILLIAM TIMOTHY
Applicants: JOHN DICKINSON STATIONERY LIMITED
Application year: 1990
Main classification: B65D27
IPC codes: B65D27