Abstract:
This invention provides an improved diverter for a flat article/mail handling system which diverter includes a conveyor for moving articles through the diverter. A mechanism is preferably provided for minimizing contact between a moving part of the conveyor and a stationary part of a diverter platen. This mechanism may, for example be a bearing surface on the platen in a contact region between a conveyor pinch roller and the platen and/or may be a recess formed in the platen in the regions thereof underlying the conveyor. The bearing may be slightly enlarged so as to raise the pinch roller a very small distance above the surface of the platen, eliminating the need for the groove.

Description:
FIELD OF THE INVENTION 
     This invention relates to systems for handling flat articles such as mail, and more particularly to an improved diverter for use in such systems. 
     BACKGROUND OF THE INVENTION 
     In transport systems for handling mail or other flat articles, there is frequently a need to provide one or more diverter stations, with some of the articles passing through the station undiverted and selected articles being diverted to an alternate transport path or so as to drop into a suitable receptacle at the station. Such diverter stations may, for example, function as sorter stations in a mail handling system. 
     Such diverters typically utilize a diverter platen or vane over which articles move when the diverter is in a non-divert position. Since in a mail handling system, the articles are normally moving at relatively high speed, the inertia of the articles is generally sufficient to propel them across the diverter without requiring an independent drive on the diverter. However, with no independent drive on the diverter, if the system is turned off for some reason, it is possible for a piece of mail or other article to get hung up on the diverter, creating a jam in the system which must be manually cleared. It is therefore preferable that inertia alone not be relied upon to move articles across the diverter platen. 
     One solution to this problem is to have the diverter platen be shorter than the articles passing thereacross, or as a minimum of substantially the same length as the shortest article passing thereover, so that by the time the trailing edge of an article leaves the drive mechanism leading into the diverter platen, the leading edge of the article has already been grabbed by the take away mechanism from the platen. However, moderate mail handling systems are required to handle mail pieces which are as small as four or five inches in length, a length shorter than that required for the diverter plate. 
     A need therefore exists to provide an independent drive for articles passing through a diverter station. However, since the diverter platen itself is preferably a passive platen which performs only the divert function and does not contain a moving drive component, a moving drive component is typically required which would interact with the platen to move articles thereacross. Such a drive component, for example a drive belt, would continue to rotate whether the platen is in its non-divert position where the moving belt/component is used to move articles across the platen or in its tilted, divert position where articles are not driven thereacross. However, in either position, contact between a moving belt/component and a stationary or non-rotating platen would create friction which in turn generates undesired heat in the apparatus, can generate dirt particles as a result of the wear which can interfere with operations of the system and/or stain mail or other articles passing through the apparatus, and most importantly, create wear on both the moving belt/component and the platen, requiring more frequent maintenance and repair for the apparatus, and thus significantly increasing both downtime and operating expense for the system. 
     While this undesired contact can be eliminated when the platen is in its non-divert position by providing a small spacing between the drive mechanism and platen, in an application such as mail handling where articles as thin as 0.007″ must be handled, it is difficult to maintain such close spacing without contact, and this is even more difficult where the articles being handled are of variable thickness, as is generally the case for mail, a typical thickness specification being from 0.007″ to 1.25″. Such variable thickness pieces are better handled by a biased pinch roller, the bias force being such that the space between the rollers automatically adjusts to handle variable thickness pieces. 
     One way in which the above problem of handling thin articles, while avoiding contact between the moving component and the platen, might be dealt with is to have the moving component be for example part of a vacuum head spaced a short distance from the platen, the vacuum permitting thin articles to be moved across the divert station without requiring physical contact between the moving component and the platen. However, vacuum is not available at all locations where article sorting is to occur and, even where available, there is frequently limited availability of vacuum. A vacuum head is also more expensive than a moving belt or other component not requiring vacuum and vacuum heads also require more maintenance. Therefore, use of a vacuum head for this application is undesirable. A diverter having an independent drive which meets the performance requirements indicated above without providing friction contact between a moving and stationery surface has not heretofore existed in the art. 
     SUMMARY OF THE INVENTION 
     In accordance with the above, this invention provides a diverter for use in a flat article handling system which diverter includes a diverter platen which is normally in a non-divert position, a drive mechanism which selectively moves the diverter platen to a tilted or slanted divert position, and permits return to the non-divert position, and a moving conveyor mounted over the platen for moving flat articles across the surface of the platen when the platen is in the non-divert position. The diverter preferably includes a mechanism for minimizing contact between a moving part of the conveyor and a stationary part of the platen. For preferred embodiments, the conveyor has a roller in at least selective contact with the platen in a contact zone thereof, and preferably in substantially continuous contact with the platen in the contact zone; and for one embodiment, the platen includes a moving bearing surface at the contact zone. The platen is normally wider than the conveyor and the platen may have a recess formed therein in an area of its surface underlying the conveyor, the recess permitting the conveyor to make good contact with thin articles passing over the platen surface without substantial friction contact with the platen when no articles are present. This latter feature may be advantageous even in the absence of a bearing surface. For another embodiment, the bearing surface is slightly above the platen surface, the raised bearing surface acting on the roller of the conveyor to maintain a small spacing between the platen surface and an adjacent surface of the conveyor. 
     The conveyor generally needs to be moved when the platen is moved to the divert position so as to not interfere with platen movement. A separate drive mechanism may be provided for moving the conveyor or the bearing surface may act on the roller to move the conveyor as the platen is moved by its drive mechanism to the divert position. At least one component may be provided biasing the conveyor to the position it is in when the platen is in its non-divert position, movement of the conveyor for the divert position being against the bias of such component. The platen may also have an underside, articles striking this underside of the platen when the platen is in the divert position and being redirected either to a suitable receptacle or to an alternate transport path. 
     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 THE DRAWINGS 
     FIGS. 1A and 1B are top front prospective views of a diverter mechanism in accordance with the teachings of this invention in its non-divert and divert positions, respectively. 
     FIGS. 2A and 2B are back elevation views of the diverter mechanism for the embodiment and positions of FIGS. 1A and 1B, respectively. 
     FIG. 3 is a side elevation view for a diverter mechanism of an alternative embodiment in the non-divert position. 
    
    
     DETAILED DESCRIPTION 
     Referring to the figures, the diverter mechanism  10  includes a diverter platen  12  and a drive mechanism which includes a pinch roller  14 , a roller  16  and a belt  18  passing over the rollers. In addition to overlying at least a portion of platen  12 , belt  18  also forms part of an article feed mechanism from the diverter which mechanism also includes a driven roller  20 , driven by a suitable motor  26 , or belt driven pulley, an idler roller  22  and lower belts  24  passing over rollers  20  and  22 . Roller  16  may be actively driven, either from motor  16  through suitable gearing or by a separate motor, or roller  16  may be an idler roller driven by contact with roller  20  or a belt  24  thereon. 
     A spring loaded pivot arm  28  is provided to bias pinch roller  14  against platen  12 . Platen  12  is fixedly mounted to a shaft  30 , secured through a rear opening in platen  12  by, for example, screws  32 . Additional openings  34  may be provided in the platen to reduce its weight. A bias spring on spring loaded pivot arm  36  may also be provided for roller  16  (FIGS. 2A and 2B) to bias the roller against drive roller  20 . The pressure applied by springs  28  and  36  is sufficiently low so that flat articles/mail of varying thickness may pass between adjacent rollers. 
     As may be best seen in FIGS. 2A and 2B, a drive mechanism  40  is provided for moving platen  12  between the non-divert position shown in FIGS. 1A,  2 A and the divert position shown in FIGS. 1B,  2 B. Mechanism  40  may be a solenoid or other suitable electromagnetic/electromechanical component, as it is for preferred embodiments, or may be a hydraulic, pneumatic or other suitable drive component. Component  40  has a drive shaft  42  terminating in a coupler which is pivotally coupled to a link  46 . Link  46  is fixedly attached to shaft  30  so that, referring to FIG. 2B, as link  46  is tilted as a result of shaft  42  being extended from drive component  40 , platen  12  is correspondingly tilted, and its leading edge raised as shown in the figures. 
     As may be best seen in FIGS. 1A and 1B, a recess  50  is formed in the top surface of platen  12  for the portion of the platen underlying belt  18 . This recess permits belt  18  to be at substantially the surface of platen  12  so as to be able to drive thin mail pieces or other flat articles across the platen without there being physical friction contact between the belt and the platen. Further, as may be best seen in FIGS. 2A and 2B, a rotatable bearing  52  is mounted in platen  12  in the contact zone between pinch roller  14  and the platen so that there is rolling contact rather than friction contact between these components when the pinch roller is in contact with the platen. When the platen is in its straight or horizontal non-divert position as shown in FIGS. 1A and 2A, friction contact can be avoided by, for example, having recess  50  and a stop/limiter on bias spring  28  or otherwise on roller  14  so that, absent an article passing under roller  14 , the roller is positioned close to, but slightly spaced from, the bottom of recess  50  so as to avoid friction contact therewith. 
     However, as may be best seen in FIG. 2B, when platen  12  is moved to its tilted, divert position, the conveyor mechanism, and in particular roller  14  and belt  18 , must be moved out of the way to permit the platen to be tilted. While either a separate drive mechanism could be provided for the conveyor to move it substantially concurrently with the movement of platen  12 , or an additional linkage could be provided off of driver  40  and shaft  42  to drive the conveyor along with the platen, for the preferred embodiment shown in the figures, bearing surface  52  bears against pinch roller  14  as platen  12  is tilted and, while the platen is in the tilted divert position, it moves and holds the conveyor  14  and  18  out of the way. This movement is against the bias of spring  28 . Therefore, when mechanism  40  is operated to return platen  12  to the non-divert position shown in FIGS. 1A and 2A, pinch roller  14 , and thus the conveyor mechanism of which it is a part, are returned to the non 20  divert position by the action of bias spring  28 . 
     In operation, referring to FIG. 2A, mail/flat articles are driven onto platen  12  from the right by drivers (not shown) to the right of the diverter mechanism, which would for example be a belt/pinch roller mechanism such as that use to take undiverted articles away from the divert station. An article entering the diverter mechanism when the mechanism is in its non-divert position as shown in FIG. 2A is grabbed by pinch roller  14  which rotates in the clockwise direction as shown by arrow  56  and pinched between this roller and bearing surface  52 , which rotates in the counterclockwise direction as shown by arrow  58 . Variations in thickness of an article arriving at roller  14  may be compensated for by roller  14  rising or falling slightly against the bias force of spring loaded pivot arms  28 . Belt  18  continues to move the article across the platen until the article is grabbed by belts  24 , the article being carried by belt  18  and belt  24  to be taken from the diverter station as shown by arrow  60 . Roller  14  and belt  18  being in recess  50  do not make friction contact with the surface of platen  12 , the only contact being between pinch roller  14  and bearing surface  58 , which contact is a rolling, non-friction contact. 
     When an article to be diverted approaches station  10 , mechanism  40  is operated to tilt platen  12  as shown in FIG. 2B, this also raising the conveyor mechanism, including pinch roller  14  and belt  18 , in the manner previously described. This results in the incoming piece of mail/flat article  62  striking the underside of platen  12  and dropping or otherwise being redirected to a suitable receptacle  64 , to a slot leading to a suitable receptacle or to an alternate transport path (i.e., for example to a conveyor belt at an angle to belts  24  leading away from the diverter stations). Once article/mail piece  62  has been diverted, the diverter may either be left in the divert position if the following article is also to be diverted, or mechanism  40  may be operated to return the diverter to its non-divert position if the next article is not to be diverted. The spacing between successive articles is sufficient to permit the diverter to move between its positions between articles. Movement of the diverter mechanism may, for example, be completed in 70 milliseconds for an illustrative embodiment. 
     FIG. 3 shows an embodiment of the invention which differs from that of FIGS. 1A-2B only in that bearing surface  52 ′ is slightly larger so that it extends a few mils above the upper surface of platen  12 . The amount by which bearing surface  52 ′ extends above the surface of the platen will depend on the minimum thickness of articles to be handled. Pinch roller  14  resting on bearing surface  52 ′ thus raises belt  18  slightly above the surface of platen  12 , for example less than 0.007″ for a mail diverter application (a spacing too small to be visible in FIG. 3) eliminating the need for recess or slot  50  in the platen. Except for this difference, the embodiment of FIG. 3 is identical to that of the earlier embodiment and operates in exactly the same way. 
     A diverter has thus been shown which facilitates diversion of a flat article by a tiltable platen with a drive/conveyor mechanism for moving the articles through the divert station, but with substantially no friction between the platen and the conveyor mechanism. While two preferred embodiments are disclosed, these embodiments are for purposes of illustration only and many variations are possible in the size, shape, orientation and general configuration of the components, depending upon application. For example, rather than mechanism  40  driving platen  12  back to the horizontal or non-divert position, mechanism  40  could merely release drive force and spring biased arm  28  acting on roller  14 , which in turn presses on bearing  52 , could function to return the platen. Platen return could also be achieved by other biasing mechanisms or by other techniques. Other drive mechanisms could also be used for tilting the platen. The orientation of the mechanism  10  and of the components thereof may also vary with application. For example, rather than platen  12  and belt  18  being substantially horizontal as shown in the figures when in the non-divert position, these components could be oriented vertically, preferably with articles moving down rather than up, although movement in both directions is possible, or the components may be oriented at substantially any angle between horizontal and vertical. Thus, while the invention has been particularly shown and described above with reference to the preferred embodiments, the foregoing and other changes in form and detail may be made therein by one skilled in the art without departing from the spirit and scope of the invention which is to be defined only by the appended claims.