Envelope feeder

Abstract: An envelope feeder has a movable weight (16) with a relatively large surface area (18) adjacent one of two substantially parallel side walls (14,15) of the envelope feeder. The weight has gears (22,23) on opposite ends of a shaft (17), on which the weight is pivotally mounted. The gears cooperate with racks (24, 26) in the two side walls to allow up and down motion of the weight while the shaft stays parallel to the feeder floor (11). Thus the position of the movable weight is never skewed. That side wall (14), which is remote from the relatively large surface area of the movable weight, has a limiter (30) extending therefrom towards the other wall (15). The limiter acts only on envelopes exceeding a predetermined width, to limit the height of a stack of such envelopes so that the power of the envelope advancing motor for feeding the envelopes from the bottom of the stack is not exceeded.

Description: This invention relates to an envelope feeder. When feeding envelopes from the bottom of a stack of envelopes in an envelope feeder, a weight must be placed on top of the stack to enable driving of the last few envelopes of the stack. One prior arrangement has placed a weight on the top envelope of the stack but has not constrained it. Another prior arrangement used a weight conforming to the top envelope and moved in a vertical path. Still another prior arrangement moved a weight on an arc while maintaining the envelope engaging surface of the weight substantially parallel to the floor of the envelope feeder. JP-A-07053063 discloses a sheet feeder having a pressing weight which can be positioned, by a pair of rollers, in a waiting position. JP-A-07 101 597 discloses a sheet feeder having a movable pressing weight and pivotal arms arranged to move the weight. According to the present invention there is provided an envelope feeder comprising: a floor for supporting a stack of envelopes which are to be fed therefrom by feeding the lowermost envelope from the stack; first and second substantially parallel side walls extending upwardly from said floor and substantially perpendicular thereto; and a movable weight supported between said first and second side walls for disposition on top of a stack of envelopes supported on said floor; characterized by maintaining means maintaining said movable weight substantially parallel to said floor at any position of said movable weight on top of a stack of envelopes. The present invention, at least in its preferred forms, is an improvement over prior arrangements in that the movable weight is constrained while having its envelope engaging surface remain substantially parallel to the floor of the envelope feeder. By constraining the weight so that its envelope engaging surface is substantially parallel to the floor of the envelope feeder at any vertical position of the weight, the weight engages the uppermost envelope in a stack of envelopes at its highest point. Thus, if an envelope is curled or twisted so as to not be flat, the constrained weight provides more force on the highest point of the top envelope of the stack, thereby tending to push that point downwardly. Since the curled or twisted portion of the envelope is at the highest point of the envelope to be fed, this curling or twisting of the envelope makes it more difficult to feed it into separating rollers, which are employed to feed only the lowermost envelope. However, by maintaining the constrained weight substantially parallel to the floor of the envelope feeder, particularly adjacent the separating rollers, this problem is substantially avoided. An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which:- FIG. 1 is a front fragmentary perspective view of an envelope feeder having a movable weight disposed in a raised or envelope loading position, and a limiter for limiting the height of the envelopes when the width of the envelopes exceeds a predetermined minimum; FIG. 2 is a rear perspective view of a portion of the envelope feeder of FIG. 1, with the movable weight in its envelope engaging position; FIG. 3 is an enlarged front fragmentary perspective view of a portion of the envelope feeder of FIG. 1, showing the movable weight held in its raised or envelope loading position; and FIG. 4 is an enlarged rear fragmentary perspective, partly in section, of a portion of the envelope feeder of FIG. 1 showing a slide for engaging the right edges of the envelopes to hold them against a left side wall of the envelope feeder. Referring to the drawings and particularly to FIG. 1, there is shown a envelope feeder 10 including a floor 11 having a plurality of envelopes 12 (shown in phantom in FIG. 2) supported thereon. The floor 11 has a right side wall 14 extending upwardly therefrom and substantially perpendicular thereto. A left side wall 15, which is substantially parallel to the right side wall 14, also extends upwardly from the floor 11 and substantially perpendicular thereto. A movable weight 16 extends between the side walls 14 and 15. The movable weight 16 includes a rotatably mounted shaft 17 (see FIG. 1) attached to a longitudinal portion 18 of the movable weight 16 through an end wall 19 (see FIG. 3) of the longitudinal portion 18 and by gear 23 on shaft 17 being trapped in recess 27 (Fig. 2) adjacent the other end of the longitudinal portion 18. This allows pivotal movement of the movable weight 16 relative to the rotatably mounted shaft 17. The longitudinal portion 18 of the movable weight 16 has a relatively large portion or area 21 at its end remote from the end wall 19. The relatively large portion or area 21 of the movable weight 16 is disposed adjacent the left side wall 15 when the movable weight 16 is in its envelope engaging position of FIG. 2. The shaft 17 has a gear 22 mounted on its end extending beyond the end wall 19 and adjacent the right side wall 14, for rotation with the shaft. Gear 23 is mounted on the shaft 17 at its end extending beyond the longitudinal portion 18 and adjacent the left side wall 15, for rotation with the shaft. The right side wall 14 has a rack 24 formed on one side of a slot 25 therein through which the shaft 17 extends. The gear 22 meshes with the rack 24. The left side wall 15 has a rack 26 along a wall of the aforementioned recess 27 in the wall. The gear 23 extends into the recess 27 to mesh with the rack 26. Thus the racks 24 and 26, which are parallel to each other, maintain the shaft 17 parallel to the floor 11 of the envelope feeder 10 during its up and down movement, through the gears 22 and 23 meshing with the racks 24 and 26 respectively. This maintains the movable weight 16 against any skewing during up and down movement of the weight along the racks 24 and 26. When the envelopes 12 are loaded into the envelope feeder 10 for disposition on the floor 11, the movable weight 16 is moved to its uppermost position on the racks 24 and 26 and is pivoted about the shaft 17 to its envelope loading position shown in FIGS. 1 and 3. In this position, an edge 28 (see FIG. 3) of the movable weight adjacent the end wall 19 rests on a ledge 29 on the interior surface of the right side wall 14. This engagement of the movable weight 16 with the ledge 29 holds the weight in its up raised position of FIGS. 1 and 3 during loading of the envelopes 12 on the floor 11 of the envelope feeder 10. The right edge of the envelopes 12 abuts a slide 34 (Fig. 4). The slide maintains the left edge of the envelopes 12 against the inner surface of the left side wall 15. The right side wall 14 (see FIG. 3) has an envelope limiter 30 extending from its inner surface substantially perpendicular thereto. The limiter 30 has a hollow semicircular portion 31 with a semicircular end portion 32. Terminal end surfaces 33 (one shown in FIG. 1) of the hollow semicircular portion 31 are substantially parallel to each other and to the floor 11. Thus, the terminal end surfaces 33 are substantially parallel to each other and are substantially parallel to the floor 11 of the envelope feeder 10. Accordingly, the terminal end surfaces 33 of the hollow semicircular portion 31 engage the uppermost of the envelopes 12 in a stack when the width of the envelopes is sufficient to extend from the inner surface of the left side wall 15 to beneath the limiter 30. Therefore, the limiter 30 limits the maximum height of a stack of the envelopes when they exceed a width greater than the distance from the inner surface of the left side wall 15 to the limiter 30. This ensures that the power of the motor advancing the envelopes 12 from the bottom of the stack will not be exceeded. The envelope engaging slide 34 (see FIG. 4) engages the right side edge of the envelopes 12 to hold the envelopes against the inner surface of the left side wall 15. The slide 34 rides in a slot 35 in the floor 11 with the slot 35 limiting the movement of the slide 34 towards the left side wall 15. The slide 34 must be capable of moving beyond the semicircular end 32 of the limiter 30, towards the right side wall 14. Thus, the slide 34 has an opening 36 to receive the limiter 30 during the motion of the slide 34 towards the right side wall 14. This is because the slide 34 must be higher than the limiter 30 when the envelopes 12 are not as wide as the distance from the inner surface of the left side wall 15 to the semicircular end 32 of the limiter 30. The slide 34 must be retained in any position to which it is moved along the slot 35. Accordingly, the floor 11 has transverse teeth 36, which comprise a rack, adjacent one edge of the slot 35 for cooperation with a downwardly projecting pawl 37 of the slide 34, to hold the slide against movement. To move the slide 34, the downwardly projecting pawl 37 is removed from engagement with one of the teeth 36 through pushing an upwardly extending arm 38 towards the left side wall 15. The envelope feeder 10 may have any suitable drive mechanism. It is however preferred to use the drive mechanism of our copending European patent application EP-A-0888989 entitled "ENVELOPE FEEDER" filed on the same day as this application. An advantage of this embodiment is that a movable weight can be constrained to always be disposed substantially parallel to the floor of an envelope feeder when the movable weight is engaging the top of a stack of envelopes. Another advantage of this embodiment is that the constrained weight is pivotable so that it contacts the highest point of the top envelope in a stack so as to apply force thereto to move the high point down if necessary. A further advantage of this embodiment is that the height of a stack of envelopes is limited when the envelopes exceed a predetermined minimum width, so that the power of the envelope advancing motor is not exceeded by the weight of the envelopes in the stack.

Claims: An envelope feeder comprising: a floor (11) for supporting a stack of envelopes (12) which are to be fed therefrom by feeding the lowermost envelope from the stack; first and second substantially parallel side walls (14,15) extending upwardly from said floor and substantially perpendicular thereto;. a movable weight (16) supported between said first and second side walls for disposition on top of the stack of envelopes supported on said floor; and characterized by : maintaining means (22-27) for maintaining said movable weight (16) substantially parallel to said floor at all vertical positions of said movable weight on top of the stack of envelopes (12). An envelope feeder according to claim 1, wherein said movable weight (16) has a larger surface area (21) for engaging a said stack of envelopes (12) in an area adjacent one of said first and second side walls (14, 15). An envelope feeder according to claim 1, including limit means (30) extending from one of said first and second side walls (14) substantially perpendicular thereto for a predetermined distance over said floor (11) for limiting the height of a stack of envelopes (12) which are of a width sufficient to extend beneath said limit means from the other (15) of said side walls, said limit means including means (33) disposed substantially parallel to said floor for engaging the top envelope in a stack. An envelope feeder according to claim 3, in which said movable weight (16) has a larger surface area (21) for engaging a said stack of envelopes (12) in an area adjacent the said other (15) of said first and second side walls, said larger surface area of said movable weight being spaced from said limit means (30). An envelope feeder according to any preceding claim, including support means (29) on said one side wall (14) of said first and second side walls for supporting said movable weight (16) in a raised and inoperative position. An envelope feeder according to any preceding claim, wherein said maintaining means comprises gears (22,23) on opposite ends of a shaft (17) on which the said weight (16) is pivotally mounted, said gears cooperating with respective racks (24,26) in said first and second side walls (14,15) to rotatably mount said shaft substantially parallel to said floor (11).

Inventors: BECKER FREIDBERT R, CHEE CHRISTOPHER G, THORNHILL WILLIAM J, BECKER, FREIDBERT R., CHEE, CHRISTOPHER G., THORNHILL, WILLIAM J.
Applicants: LEXMARK INT INC, LEXMARK INTERNATIONAL, INC.
Application year: 1998
Main classification: B65H1
IPC codes: B65H1