BACKGROUND

The present invention relates to an improved implement for opening letter envelopes.

DESCRIPTION

Conventional letter openers for letter envelopes are elongated devices constructed with handles that terminate in narrow blades. To use a conventional letter opener, the tip of the blade is inserted into a small gap formed at an edge of the envelope where the envelope flap is folded into a small gap formed at an edge of the envelope where the envelope flap is folded over and sealed to the body of the envelope. The envelope is then held immobile and the blade is pulled along the length of the flap at the fold therein while tension is exerted between the fold of the flap and the body of the envelope.

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Conventional envelope opening devices are inadequate for several reasons. Not infrequently the blade of a conventional letter opening device will engage not only the flap of the envelope, but also folded papers within the envelope. When this occurs, the cutting action of the blade severs not only the envelope, but also papers within the envelope.

The process of opening an envelope with a conventional letter envelope opener is also relatively- slow. The user must first locate an opening adjacent to a strip of adhesive on the envelope flat, insert the tip of the letter opener into that opening, and then run the letter opener along the length of the fold of the flap. While the total time required to open a single envelope is minimal, the labor cost in opening a multitude of envelopes in large mailrooms with conventional letter openers is very substantial. Furthermore, the time required for opening mail is further lengthened when the letter opener engages papers within the envelope, in the manner previously described, and also when the letter opener snags on a paper clip or staple within the envelope.

Further delays in opening mail are frequently encountered when the envelope construction is such that a gap at the fold of the flap cannot be located. In some envelopes the adhesive'strips do extend entirely along both edges of the envelope flap, so that a gap at the fold within which to insert the envelope opener does not exist. This difficulty is also encountered when the flaps of envelopes are sealed with tape. The only solution when such' a difficulty arises is to manually tear the envelope.

While various implements have been devised to attempt to overcome the difficulties of conventional letter envelope openers, most such devices have been overly complex and expensive or unsatisfactory in their operation. U.S. Patent No. 3,619,902 describes a hand held device in which a blade is movable in longitudinal reciprocation with the housing and is spring biased to extend across a transverse channel designed to receive

the edge of a letter envelope. The bias of the spring is overcome to allow an envelope to be inserted into the transverse slot, and the blade is then released. Because the force within which the blade bears against the envelope is controlled entirely by the spring, the blade will sometimes bear too heavily against the structure of the envelope, thus resulting in seizure and tearing of the envelope when the envelope is pulled lengthwise along the transverse slot. At other times, the blade bears too lightly against the envelope, thus failing to open it when the envelope is pulled through the slot. Furthermore, since the blade is spring biased outwardly into the slot, it is normally exposed. This can cause injury to the user's hand if the device is handled inattentively. The blade is likely to become dull or broken, since coins, keys and other metal objects can lodge in the slot against the blade.

SUMMARY OF THE INVENTION

The present invention is directed to an improved envelope letter opening implement which may be used to open envelopes far more quickly than is possible with conventional envelope openers. Unlike many conventional envelope openers, the implement of the invention does not require the presence of an opening at which a tear is to be initiated. To the contrary, the envelope opening implement of the invention initiates a cut along one edge of the envelope by penetration from without, rather than by an initial insertion into an opening and tearing from within. Consequently, time is not lost in searching for an appropriate opening at the edge of the flap of the envelope so as to initiate a tearing action.

A further advantage of the invention is that the contents of an envelope cannot be damaged utilizing the envelope opening implement of the invention. It is not necessary to insert a blade deep into the interior of an envelope where it is likely to engage the contents of the envelope using the envelope opening implement of the invention. To the contrary, the blade of the implement of the invention is directed through the structure of the envelope only along a very narrow margin extremely close to an edge of the envelope.

The device of the invention employs a body having an envelope receiving slot, channel or crevice. Both the width and depth of the slot are quite small. Once the edge of the envelope is inserted into the slot, the blade of the envelope opening implement is directed laterally into the slot, but not entirely across the width the slot. Consequently, once the envelope is pulled through the slot the blade slices through the structure of at least one side of the envelope, but without totally impaling and immobilizing the envelope within the slot.

A spring biasing means which urges the blade away from the slot, so that the blade is only exposed during the act of slitting an envelope.

One device of the invention employs a ram which is guided in longitudinal reciprocation within a cavity in a surrounding sleeve or slide. The sleeve is formed with a transverse channel of fixed, predetermined width at one end extremity thereon. The ram is disposed within the cavity in the hollow sleeve and carries a blade having a cutting edge directed towards the transverse channel. However, a spring acting between the

ram and the sleeve urges these relatively movable elements in such a manner that the cutting edge of the blade is held retracted within the cavity of the sleeve unless manual force is exerted to overcome the bias of the spring.

When the device is carried in a pocket or handbag, together with a user's other personal belongings such as money, keys, nail clippers and the like, the retracted blade cannot slice the lining of a purse or cut the fabric of a pocket. Furthermore, even if keys or coins do lodge within the transverse channel or slot, the blade of the letter envelope will not be blunted by metal to metal contact.

A further, very significant advantage of the invention is that pressure with which the blade is pressed against an envelope when the device is utilized to open an envelope is entirely determined by the user. The user employs a manual force to move the sleeve and ram in longitudinal reciprocation relative to each other so that the cutting edge of the blade penetrates into the transverse channel once a letter to be opened has been inserted into the channel.

A user can sense by the nature of the resistance of the passage of an envelope through the transverse slot if too much or too little force is being used to press the blade against the envelope. If the force is too great, the envelope will tend to seize and tear. This effect is immediately detected by the tactile senses of the user. In such a circumstance, considerable resistance will be felt both by the hand of the user pulling the envelope through the slot, and by the hand of the user which is exerting the force to overcome the

spring bias. The corrective action of reducing the force on the blade is performed almost instinctively by the user. Similarly, the lack of any significant resistance in pulling the envelope through slot will be immediately signaled by the tactile senses of the user. Again, the user will increase the force to cause the cutting edge of the blade to penetrate further into the transverse slot, almost instinctively.

In one broad aspect, the present invention is a device for opening an envelope comprising a hollow sleeve member defining an envelope receiving slot. A ram element extends into the sleeve member whereby the sleeve and the ram element are movable relative to each other in longitudinal movement between the ram and the sleeve to prevent the cutting edge of the blade from extending across the entire width of the slot.

In another broad aspect, the present invention is a device for opening an envelope comprising a body defining an envelope receiving slot of a predetermined width and length, a blade having a cutting edge and reciprocally mounted within the body so that the cutting edge is movable to project into the slot in the direction of the width thereof. Means is mounted on the body for adjustably limiting the extent to which the cutting edge projects into the slot.

The width of the slot is preferably no greater than about 0.5 centimeters and the depth of the slot beneath the blade is preferably even less. The slot defined in the body is a crevice which is preferably of a U-shaped or channel-shaped configuration and the distance from the blade to the floor of the channel is preferably no greater than two millimeters.

To open an envelope, the device of the invention is preferably held with the channel-shaped slot inverted over the top edge of the envelope. This allows the contents of the envelope to drop toward the opposite, lower edge, and away from the upper edge. When the upper edge of the envelope is inserted into the slot, the user overcomes the bias of the spring to force the blade longitudinally into the transverse slot. The envelope is then drawn through the slot. The longitudinally projecting blade presses against the structure of the envelope a distance of only about two millimeters or less from the upper edge of the envelope. The chances of the contents of the envelope being damaged are thus extremely minimal.

The blade .employed in the letter opening device of the invention is preferably a razor-type blade normally shaped in a parallelogram configuration with cutting edges on oppose ends. The cutting edges of the blade are inclined at angle relative to the length of the blade and the blade is removably and reversibly mounted on a ram within the hollow sleeve or on a slide within the body.

Preferably, either one or the other of the ram and the surrounding sleeve is formed with a laterally projecting, depressible member. The other of the sleeve and the ram is formed with a longitudinally aligned track which is closed at both ends. The depressible member thereby extends into the track to releasably hold the sleeve on the ram. However, the depressible member can be depressed, thus allowing the ram and the sleeve to be separated from each other.

When the ram and sleeve are separated, the blade is exposed so that the disposition of the blade can be reversed. Thus, a fresh cutting edge of a double edged blade may then be directed toward the transverse channel. The ram element and the sleeve member are then reengaged with each other so that the depressible member again ridges in the track and holds the ram and sleeve together until purposeful separation is desired.

The blade can also be reversed in the disposition in which it is mounted upon the ram so that the cutting edge may alternatively be inclined toward either of the opposite ends of the transverse channel. Thus, the letter opening device of the invention can easily be converted for either right-handed or left- handed use. Also, when one cutting edge of the blade becomes dull, the blade is simply turned one hundred eighty degrees within the body of the implement, thereby orienting the opposite cutting edge in a position for use.

Only the very extreme tip of the razor blade extends into the channel approximately midway along the total depth of the channel. The channel is preferably no greater than 0.5 centimeters in width so- that a user cannot inadvertently insert a fingertip into the channel where it might be injured by the razor blade. Although the cutting edge is quite sharp, it is never exposed except during operation, unlike a conventional letter opener. Consequently, it is much safer to use and carry than a conventional opener.

The means for adjustably limiting the extent to which the cutting edge projects into the slot preferably may include a circular dial which is

eccentrically mounted on a handle from which the ram projects. The dial is located in the path of movement relative to the slide or sleeve mechanism. Pressure is exerted by a finger of a user on the end of the slide or sleeve mechanism to urge it toward the ram. This relative longitudinal reciprocal movement between the slide and the ram causes the cutting edge of the blade to project into the slot. The dial forms an abutment which limits the longitudinal movement of the slide.

Alternatively, the means for adjustably limiting the extent to which the cutting edge projects into the slot may be mounted on the body in the path of a slide mechanism. The slide mechanism is used to push the blade toward the slot so that the cutting edge projects into the slot. By selectively rotating the dial about its eccentric axis, the longitudinal limit of movement of the slide can be altered thereby altering the extent ^" to which the tip of the cutting edge of the blade projects into the slot. The dial is configured so that even when the slide is permitted to move a maximum length along its path of travel, the tip of the cutting edge will not extend entirely across the width of the slot.

In one preferred embodiment of the invention, the blade remains entirely withdrawn from the transverse slot or channel until the sleeve and ram are moved in relatively longitudinal reciprocation by manual force exerted to overcome the spring bias.

In the embodiment with a slide, the slide is preferably spring biased rearwardly so that the blade remains drawn entirely into the body of the implement until the actuating element of the slide on the surface of the body is manually pressed forward.

DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view illustrating the manner of use of a preferred embodiment of a safety envelope opening implement according to the invention.

Figure 2 is an exploded perspective view of the operation portion of the envelope opening device of Figure 1.

Figure 3 is a front sectional elevational detail of the slide or sleeve of the implement of Figure 2 taken along the lines 3-3 thereof.

Figure 4 is a slide sectional elevational view of the implement of figure 2 shown in its normal condition prior to operation.

Figure 5 is a side sectional elevational view of the implement of Figure 2 shown in its operating condition.

Figure 6 is a perspective view illustrating the manner of use of another preferred embodiment of an envelope opening implement according to the invention.

Figure 7 is an exploded perspective view of a portion of the implement of Figure 6.

Figure 8 is a side elevational sectional view of the implement of Figure 6.

Figure 9 is a sectional plan detail taken along the lines 9-9 of Figure 8.

Figure 10 is an isolated plan view of a portion of the body of the device depicted in Figure 8.

Figure 11 is a sectional elevational detail illustrating a portion of another alternative embodiment of the invention.

DESCRIPTION OF THE EMBODIMENT

Figure 1 illustrates the manner of use of an implement 10 constructed in accordance with the invention. The. implement 10 is used for opening envelopes such as the envelope 12. The implement 10 is comprised of a hollow sleeve member 14, a ram element 28, a blade 32, and a coil spring 38.

The sleeve 14 is depicted in isolation in Figures 2 and 3, and is constructed generally in the form of a hollow, rectangular prism. The sleeve 14 is open at its lower end 16 and is closed at its opposite end by a transverse end wall 18 and by a transverse partition 20 which together define a transverse envelope receiving crevice, slot or channel 22. The channel 22 is of predetermined width as defined by the distance between the interiorly facing side 24 of the end partition 18 and the side 26 of the partition 20. The facing sides 24 and • 26 of the partitions 18 and 20 respectively form the walls of the channel 22. The width of the channel 22 is preferably no greater than about 0.5 centimeters. The distance between the floor of the channel 22 and the facing surface of the blade 32 when the blade is extended into the channel 22 is likewise predetermined and preferably is no greater than about 2 millimeters.

Interiorally of the partition 20 the sleeve 14 defines a cavity 30 of rectangular cross section.

The ram 28 is likewise shaped generally as a rectangular prism and is of a size which fits within the cavity 30 defined within the sleeve 14. The ram 28 is mounted for longitudinal reciprocation within the cavity 30 and extends into the open end 16 of the sleeve 14. A parallelogram shaped blade 32 is also disposed within the cavity 30 and has a cutting edge 34 directed at an inclination toward the envelope receiving crevice or channel 22. An adjustable blade movement control means is provided in the form of a disk 36 which is eccentrically mounted with respect to one or the other of the ram 28 and the slide or sleeve 14. The adjustable disk 36 limits the extent to which the cutting edge 34 of the blade 32 projects into the crevice or channel 32. This limit of projection is less than the width of the channel 22. The implement 10 is further comprised of a spring 38 which acts between the sleeve 14 and the ram 28 to urge the cutting edge 34 of the blade 32 away from the transverse crevice or channel 22 and into the cavity 30.

The cavity 30 is of uniform cross section throughout the longitudinal length of the sleeve 14 and is of a square or rectangular cross sectional configuration. The side 40 of the transverse partition 20 defines a transverse bearing wall against which the upper end of the spring 38 presses.

The ram 28 likewise has a uniform cross sectional configuration. This configuration corresponds to that of the cavity 30 which is bounded by the interior surfaces of the sleeve 14. As illustrated, the ram 28 is formed with a base 42, the upper surface 44 of which also

defines a transverse bearing wall. The transverse bearing wall 44 of the ram 28 is longitudinally displaced from the opposing parallel transverse bearing wall 40 of the sleeve 14. A U-shaped abutment ledge 46 is defined 5 at the transition between the ram 28 and a handle 48 and is dimensioned to correspond to the wall thickness of the front wall 50 and the side walls 52 and 54 of the slide 14.

The ram 28 is also formed with side walls 56 10 and 58 and a back wall 60 that rise upwardly from the base 42 in a U-shaped configuration, as best illustrated in Figure 2. Together, the side walls 56 and 58 of the ram 28, the back wall 60 of the ram 28, the front wall 50 of the slide 14, and the opposite transverse bearing end 15 walls 40 and 44 of the slide 14 and the ram 28, respectively, define a spring compartment 62. The enclosed spring compartment 62 defined by the ram 28 and ' the slide 14 is of oblong, rectangular configuration.

The spring compartment 62 accommodates the 20 coil spring 38 which is compressed and disposed between the slide 14 and the ram 28 as best illustrated in Figures 4 and 5. The wall 40 is formed by the structure of the slide 14 and the wall 44 is formed by the structure of the ram 28. The compressed coil spring 38 25 is longitudinally aligned and oriented within the compartment 62 and is compressed between the opposite end walls 40 and 44.

A spring guide 64 is interposed between the spring 38 and the end wall 44 of the base 42 of the ram 30 28. The spring disk 64 has a base 66 formed in a rectangular or circular configuration to fit into the spring compartment 62 against the bearing wall 44. A

disk shaped center projection 68 extends upwardly from the base 66 and fits concentrically within the lowermost coils of the spring 38. The spring guide 64 thereby serves as a means for maintaining the coil spring 38 in longitudinal alignment between the transverse bearing walls 40 and 44. The spring guide 64 also aids in immobilizing the lower edge 70 of the blade 32 within the spring compartment 62.

As illustrated in Figures 2, 4 and 5, the back wall 60 of the ram 28 defines a laterally projecting stud 72 which extends a short distance outwardly into the spring compartment 62. The blade 32 is provided with a surface discontinuity in the form of a central, circular aperture 74 therethrough. The laterally projecting stud 72 on the back wall 60 of the ram 28 is located in longitudinal alignment with the aperture 74 of the blade 32 when the blade 32 is seated in the spring compartment 62. the stud 72 thereby fits into and extends through the aperture 74. The blade 32 is thereby immobilized relative to the ram 28 by engagement of the laterally projecting stud 72 in the aperture 74 of the blade 32. The stud 72 thereby keeps the lower blade edge 70 from contacting the bearing wall 44.

As previously noted, the spring guide 64 further aids in immobilizing the blade 32, since the lower edge 70 of the blade 32 is laterally entrapped between the base 66 of the spring guide 64 and the back wall 60 of the ram 28. The spring guide 64 aids in constraining the blade 32 against lateral movement within the spring compartment 62. While the aperture 74 extends completely through the blade 32, it is to be understood that the blade 32 could be formed with a notch or any

other surface discontinuity in registration with the blade engaging stud 72.

As best illustrated in Figure 3, the sleeve 14 is formed with a longitudinally oriented, elongated track 80 which is closed at both of its rounded ends 82 and 84.

The track 80 is formed as a slot which extends entirely through the structure of the back wall 86 of the sleeve 14. As illustrated in Figures 4 and 5, a downwardly inclined depressible tang 88 is formed ont he outwardly facing surface of the back wall 60 of the ram 28.

The tang 88 resides in registration with the track 80 and normally projects into the track 80 to hold the ram 28 and the sleeve 18 together in a releasable manner. That is, as is evident from Figure 4, the sleeve 14 cannot be pulled upwardly and free of the ram 28 with the tang 88 projecting into the track 80, since the tang 88 will lodge in abutment against the end 84 of the track 80, thereby preventing the ram 28 and the sleeve 14 from separating. However, when it is desired to change the blade 32 or reverse the orientation of the blade 32 within the spring compartment 62, a user merely inserts a small implement, such as a pen or pencil, into the track 80 to depress the tang 88 inwardly toward the back wall 60 of the ram 28 a sufficient distance so that the tang 88 no longer projects into the track 80. The sleeve 14 can thereupon the releasably withdrawn with the ram 28.

Once the blade 32 has been reoriented or replaced, the sleeve 14 is merely oed into longitudinal alignment withint he ram 28 and the ram 28 is inserted into the open end 16 of the sleeve 14. As the ram 28 and

the sleeve 14 are moved together the depressible nature of the tang 88 will allow the back all 86 of the sleeve 14 to force the tang 88 inwardly toward the back wall 60 of the ram 28 to allow the back wall 86 of the sleeve 14 to clear the tang 88. Once the sleeve 14 and the ram 28 have been pushed together sufficiently the tang 88 will arrive in registration with the track 80. Thereupon it will spring outwardly to again releasably engage and hold the sleeve 14 and the ram 28 together.

In the embodiment of the implement 10 depicted and described, the disk 36 is mounted for rotation relative to the ram 28 by means of a fastener 90 which has a shank that extends through the opening 92 in the disk 36 is thereby eccentrically mounted about an axis 94 that is perpendicular to the plane of the disk 36.

The disk 36 is mounted for adjustable rotation about an eccentric axis 94 oriented perpendicular to the direction of longitudinal reciprocation of the sleeve 14. The disk 36 may be rotated between a position in which the widest portion of its structure faces the sleeve 14 and a position in which the narrowest portion of its structure faces the sleeve 14, as depicted in Figure 5. When rotated to the disposition of figure 5, the reciprocal range of the sleeve 14 is at a maximum, since the structure of the disk 36 limits the forward advance of the sleeve 14. The eccentrically mounted disk 36 is located in the path of longitudinal movement of the sleeve 14. Conversely, when the disk 36 is rotated about the axis of the shank of the fastener 90 to bring the widest portion of the structure of the disk 36 into abutment facing the external sleeve 14, the range of longitudinal reciprocation of the sleeve 14 relative to the ram 28 is minimized.

As illustrated in Figures 4 and 5, the disk 36 has been rotated relative to the handle 48 so that the eccentric axis of rotation 94 resides between the sleeve 14 and the geometric axis 96 and in linear alignment therewith. This allows the sleeve 14 and the ram 28 to be moved together to the maximum extent possible, as illustrated in Figure 5. However, even in this position the cutting edge 34 of the blade 32 projects into the channel 22 less than the predetermined width thereof. Rotation of the disk 36 in any direction about the eccentric axis 94 will only result in a reduction of the extent to which the blade 32 protrudes into the channel 22.

The eccentrically mounted disk 36 is designed to halt relative movement between the sleeve 14 and the ram 28 within a variable distance selected within a predetermined range. By rotating the disk 36 the advanced position of the blade 32 can be closely adjusted to fine tune the precision cutting clearance between the - cutting edge 34 of the blade 32 and the facing surface 24 of the end partition 18 to compensate for tolerances, blade wear and resiliency of the structural components of the device.

In the operation of the implement 10, the user grips the envelope opening device 10 in one hand 100 and at the same time grips an envelope 12 to be opened in the other hand 102. The top edge 104 of the envelope 12 is then inserted into the slot or channel 22 near the fingers of the user's hand 102. The user then uses the forefinger of the hand 100 to squeeze on the sleeve 14 to press the sleeve 14 and the ram 28 together to thus bring the cutting edge 34 of the blade 32 out of the cavity 30

within the sleeve 14 to a position such as that depicted in Figure 5. In so doing, the user overcomes the bias of the compressed coil spring 14 at which the transverse partition 18 is located. The corresponding cross sectional configurations of the longitudinally extending walls 56, 58 and 60 of the ram 28 and that of the walls 50, 52, 54 and 86 of the sleeve 14 serve as a guide to ensure that only relative longitudinal reciprocal movement occurs between the sleeve 14 and the guide 28.

With the end partition 18 pressed inwardly toward the ram 28, as depicted in Figure 5, the user in a quick movement runs the letter opening device 10 along the upper edge 104 of the envelope 12 away from the hand 102. The envelope edge 104 is pinched between the cutting edge 34 of the blade 32 and the interiorly facing surface 24 of the end partition 18. As the envelope 12 is pulled through the transverse slot 22, either one or both sides of the paper of the envelope 12 will be neatly sliced, thus allowing the contents of the envelope 12 to be readily withdrawn. The forwardly projecting cutting edge 34 of the blade 32 will slice an opening in at least the side of the envelope 12 facing the blade 32 along the entire top edge 104. When the user releases the foregoing from the transverse end partition 18 of the sleeve 14, the coil spring 38 will push the sleeve assembly 14 away from the ram 28, thereby withdrawing the cutting -edge 32 back into the cavity ^" 30 of the sleeve 14.

Figure 6 illustrates the manner of use of a second embodiment, namely, implement 110 opening an envelope 112. The device 110 is comprised of a body 114 defining a cavity 116 therewithin and forming a transverse channel or slot 118 of a predetermined width, as depicted in Figure 8. A parallelogram-shaped razor

blade 120 is disposed within the cavity 116 and has cutting edges 122 and 123. The cutting edge 122 is directed toward the transverse channel 118. An externally actuable means in the form of a slide assembly 124 is provided for moving the blade 120 is longitudinally reciprocal fashion between a retracted position entirely within the cavity 116 and an extended position in which the cutting edge 122 projects longitudinally into the channel 118, as depicted in Figure 8. An adjustable blade movement control means in the form of a dial assembly 126 limits the extent to which the cutting edge 122 projects into the channel 118 to a predetermined distance which is less than the entire width of the channel 118.

The body 114 is an elongated structure which defines a handle 128 which may be gripped in the palm of a user's hand 100. The body 114 is formed of separable mating elements 130 and 132 which are releasably securable together to define the cavity 116 therebetween. The body portion 130 is an elongated, tunnel-shaped structure formed of injected molded plastic and having a roof 140, side walls 133 and 135, and stiffening partition 134 and 136 which extend transversely between the walls 133 and 135. The stiffening partition 136 is divided by two discontinuities near its center to form a central anchoring post 138 which depends from the room 140 of the body portion 130. The extreme forward end of the body portion 130 is turned downwardly in an overhanging lip 142 which forms one wall of the channel or slot 118. A small circular opening 144 is defined in the room 140 near the lip 142 and a larger, longitudinally elongated rectangular opening 146 is defined in the room 140 between the circular opening 144 and the transverse partition 136.

The body 132 is an elongated, slab-like structure which is turned upwardly at its opposite ends to define lips 148 and 150 which rise from a base 152. The exterior surfaces of the lips 148 and 150 are rounded convexly outwardly at the opposite ends of the body portion 132. The rounded transition between the lip 150 and the base 152 aids in guiding the top edge 156 of the envelope 112 into the channel or slot 118.

The body portion 132 includes a plurality of pairs of fastening posts 158 which rise from the interior surface of the base 152 just within the lateral margins of the longitudinal edges 160 of the base 152. The marginal distance between the fastening posts 158 and the longitudinal edges 160 of the base 152 are just sufficient to receive the wall thicknesses of the downwardly projecting side walls 133 and 135 of the top portion 130 of the body 114. The fastening posts 158 press laterally outwardly against the side walls 133 and 135 to hold the body portions 130 and 132 together by means of frictional engagement. That is, the fastening posts 158 are fictionally engaged with the side walls 133 and 135.

At the front end of the body portion 132 a pair of interior, laterally spaced, longitudinal, mutually parallel tracks 162 extend rearwardly from the lip 150 and are spaced inwardly from the edges 160. The tracks 162 support the blade 120 from beneath.

The slide assembly 124 is an injection molded structure which includes an external manually actuable generally rectangular shaped element 166 and an internal element 168 depending from the underside of the external

element 166. The external element 166 slides along the top outer surface of the roof 140 of the body portion 114. The internal element 168 is of a generally L-shaped overall configuration and projects downwardly through the rectangular opening 146 in the body roof 140. Beneath the roof 140 the internal element 168 defines a downwardly directed generally circular blade engaging post 170 near its forward end. The internal element 168 is also provided with a pair of parallel, longitudinal reciprocation of the slide assembly 124. The rails 172 embrace and laterally constrain the side edges of the blase 120 and likewise embrace and bracket the parallel tracks 162 on the body member 132. The blade engaging post 170 extends through the opening 174 in the blase 120 to secure the blase 120 relative to the slide assembly 124. The tracks 162 laterally constrain and guide the rails 172 in longitudinally reciprocal movement and support the blase 120 from beneath as the internal elements 168 longitudinally traverses the length of the rectangular opening 146. The tracks 162 thereby serve as a guide means within the cavity 116 to slidably engage the internal slide element 1658 of the slide assembly 24 and to limit movement of the slide assembly 24 to longitudinal reciprocation.

As best illustrated in Figure 9, the blade 120 has cutting edges 122 and 123 at its opposite ends. A circular aperture 174 of the blade 120 is located in the exact center of the blade so that either cutting edge 122 or 123 may be positioned to project forwardly toward the slot 118 the same distance relative to the slide assembly 124. In Figure 9, the cutting edge 122 is oriented to project toward the slot 118. Should the cutting edge 122 become dull, however, the body portions 130 and 132 are merely pulled apart to expose the blade 120. The blade

120 is then lifted to disengage the blade engaging post 170 from the aperture 174 and is then turned one hundred eighty degrees in the same plane. The blade engaging post 170 is then re-engaged in the aperture 174 with the positions of the cutting edges 122 and 123 reversed.

Also, the device 110 may be easily converted for either right-handed or left-handed use by merely lifting the blade 120 from the blade engaging post 170, rotating it one hundred eighty degrees about its longitudinal axis, and re-engaging the blade engaging post 170 in the aperture 174. As illustrated in Figure 9, the cutting edge 122 is oriented at an acute angle relative to the transverse channel 118, and extends up and to the left in the view of Figure 9. When the implement is converted for use with a different hand, the position of the blade 120 is reversed so that the cutting edge 122 will extend up and to the right at the same acute angle, thus, the angle of orientation of the cutting edge 122 relative to the channel 118 is likewise reversible.

The letter opening device 110 is provided with a coil return spring 180 which has hooks at opposite ends for secure ent to the implement body 114 and to the internal element 168 of the slide assembly 124. Specifically, one hooked end of the coil spring 180 is engaged in an opening in a longitudinally oriented rearwardly projecting longitudinally centered tang 182 on the internal element 168 of the slide assembly 124. The opposite end of the spring 180 is hooked about the spring anchoring post 138 formed in the transverse partition 136. The spring 180 thereby acts between the body and the internal element 168 to urge the blade 120 away from the slot 118. The slide assembly 124 is thus pulled

rearwardly to the rearmost extremity of the rectangular opening 146 by the spring 180 unless manually pressed forward by the thumb 184 of a user in the manner depicted in Figure 6.

The control means 126 is comprised of a dial

184 having a circular eccentrically located opening 186 defined therethrough. The diameter of the eccentrically located opening 186 defined therethrough. The diameter of the eccentrically located opening 186 is greater on the upper surface of the dial 184 than at the lower surface thereof, so that an annular bearing ledge is defined to seat the annular flange 185 of the T-nut 188 sets upon the bearing ledge and holds the barrel 187 out of contact with the upper surface of the body portion 130. The shank of a machine screw 190 is inserted through the opening 144 in the roof 140 of the body portion 130 and is threadably engaged within the tapped barrel 187 of the T-nut 188. The screw 90 may be tightened sufficiently to hold the dial 84 at a selected position of rotation atop the body element 130 but not so tightly as to prevent purposeful rotation of the dial 184 by the hands of the user.

The dial disk 184 is mounted for adjustable rotation about an eccentric axis oriented perpendicular to the direction of longitudinal reciprocation of the slide assembly 124. The dial 184 may be rotated between a position in which the widest portion 189 of its structure faces the external manually actuable element 166 of the slide assembly 124. When rotated to this disposition, the reciprocal range of the slide assembly 124 is at a minimum, since the structure of the dial 184 limits the forward advance of the manually actuable element 166 to a minimum. The eccentrically mounted dial

184 is located in the path of longitudinal movement of the externally actuable slide assembly 124. Conversely, when the dial 184 is rotated about the axis of the shank of the screw 190 to bring the narrowest portion 191 of the structure of the dial into abutment facing the external slide element 166, the range of longitudinal reciprocation of the internal element 168 of the slide assembly 124 is maximized. Even so, however, the width of the abutting portion 191 of the dial 184 is sufficient to prevent the cutting edge 122 of the blade 120 from reaching the interiorly facing surface of the lip 142.

The width of the slot 118 is no greater than about 0.5 centimeters between the mutually facing surfaces of the lips 142 and 150 of the body portions 130 and 132, respectively. This separation is too small to admit even the tip of a finger of a user which might inadvertently be directed into the slot or channel 118. As a consequence, the cutting edges 122 and 123 of the blade 120 cannot injure the hand of a user. The separation between the blade 120 and the roof 140 is preferably less than 2 millimeters.

In the operation of the implement 110, the user grips the envelope opening device in one hand 100 and at the same time grips an envelope 112 to be opened in the other hand 102. The top edge 156 of the envelope 112 is then inserted into the slot 118 near the fingers of the user's hand 102. The curvature of the lip 150 aids in bringing the top marginal edge 156 of the envelope 112 into seated registration against the roof 140 in the slot 118. The user then rotates the dial disk 184 as desired to control the extent to which t he blade 120 can be projected longitudinally into the slot 118 in the direction of the width thereof. The appropriate

position of the dial disk 184 will vary among users, since different users are likely to press harder on the external manually actuable element 166 of the slide assembly 124. The user presses external element 166 toward the lip 142, thereby overcoming the bias of the spring 180 and pressing the cutting edge 122 of the blade 120 into the slot or envelope receiving crevice 118. Within the body cavity 116 the tracks 162 cooperate with the rails 172 to ensure that the blade 120 can move only in longitudinally reciprocal fashion. With the external manually actuable element 166 pressed forwardly, the user in a quick movement runs the letter opening device 110 along the upper edge 156 of the envelope 112 away from the hand 102. The envelope 156 is pinched between the cutting edge 122 of the blade 120 and the interiorly facing surface of the body lip 142 as the envelope 112 is pulled through the transverse slot 18. Either one or both sides of the paper of the envelope 112 will be neatly sliced, thus allowing the contents of the envelope 112 to be readily withdrawn. The forwardly projecting cutting edge 122 of the blade 120 will slice an opening in at least the side of the envelope 112 facing the blade 120 along the entire top edge 156. When the user releases the thumb 184 from the external element 166 of the slide assembly 124, the coil spring 180 will pull the blade 120 back into the cavity 116 of the body 114.

The eccentric disk-iike dial 184 is designed to stop the manually actuated slide element 166 within a variable distance selected within a predetermined range. With the dial 184, the advanced position of the blade 120 can be closely adjusted to fine tune the precision cutting clearance between the cutting edge 122 of the blade 120 and the facing surface of the lip 142 to

compensate for the tolerances and resiliency of the structural components of the device.

No tool is required to change the razor blade 120. To.the contrary, the razor blade 120 may be exposed and reversed for either right-handed or left-handed use, or to provide a fresh cutting edge in a matter of a very few seconds by merely snapping the body portions 130 and 132 apart and manually repositioning the blade 120 as desired.

All of the operating mechanisms of the letter opening element 110 are located at one end of the structure, thus providing enough room at the opposite end of the cavity 116 for inclusion of some other implement, such as a ball point pen or a utility knife. Also, spare blades 120 can be stored in the opposite end of the cavity 116. The device of the invention is extremely simple in construction and is easy to assemble. It has a very low cost of manufacture and requires minimal maintenance. The device 110 is quite small and may be easily carried in the manner of a ball point or fountain pen.

Figure 11 illustrates an alternative embody 110' of a letter opening implement according to the invention. Corresponding parts of the implement 110' are indicated by the same reference numbers as in the implement 110. The primary difference of the implement 110' from the device 110 is that the spring 180 is connected to an anchoring post 138' that extends downwardly from the roof 140 forwardly of the partition 136', and the body portions 130' and 132' are held together by frictional engagement of the transverse

partition 36' within a groove defined in a gripping element 58' .

Undoubtedly, numerous variations and modifications of the invention will become readily apparent to those familiar with letter opening devices. For example, the track 80 could be formed on the ram 28 while the tang 88 could be formed on the sleeve 14.