Patent Publication Number: US-2015082960-A1

Title: Feeding And Cutting Unit For A Dispenser Of Paper Sheets Obtained From A Continuous Band

Description:
The present invention relates to devices for the controlled dispensing of portions of paper from a continuous band to be used as towels, and in particular to a dispenser of the manually-operated type in which it is the pull exerted by the user on the tip of paper projecting from the dispenser that controls the feeding of a pre-established length of band and the cutting thereof. Specific reference will be made in the following to a dispenser of paper for towels, yet it is clear that what is being said is also applicable with obvious modifications to toilet paper, kitchen paper and the like. 
     There are well-known dispensers of paper towels obtained from a continuous band in which the cutting blade is fixed and the user must only carry thereon the portion of paper pulled out from the dispenser, so as to severe it from the band and thus be able to use it. This type of device, described for example in JP 2006034596, is very simple and reliable but it leaves up to the user both the feeding function, i.e. the choice of the length of the portion of paper to be cut with consequential unavoidable wastes, and the cutting function, which implies the presence of a blade in a region always accessible to the user and therefore potentially dangerous. 
     A natural evolution of said device is the automatic paper cutting, still through a manually-operated device and without resorting to motor-driven solutions which are much more expensive, bulkier and less reliable. 
     An example of such a kind of device is a device in which a blade-driving cam is provided that is connected to the paper-feeding roller, so that the blade springs out radially from a rest position within a longitudinal slot formed in the roller itself to a cutting position wherein it intersects the paper outside the roller. This involves a clear danger of a possible springing out of the blade while the user is manually performing the paper inserting operation on the feeding roller, moreover the spring-driven mechanism is noisy both in the cutting phase and when the blade is returned to its rest position. An example of this type of cutting mechanism is disclosed in GB 837194. 
     Another kind of device similar to the preceding one is a device in which the blade acts on the strip of paper in a radial direction from outside towards the inside of the feeding roller by entering a longitudinal slot thereof. In this case, the blade is mounted on a cutting group by means of a fork pivoted and laterally guided so as to be operated in synchronism with the rotation of the roller, and an example of such a device is described in the applicant&#39;s previous application WO 97/36531. Though being safer, however also this solution implies a quite noisy and fairly complicated mechanism which is therefore expensive and not completely reliable. Furthermore, the presence of the cutting mechanism outside the feeding roller makes the device bulkier. 
     A different type of cutting mechanism is that in which a first blade is mounted on the feeding roller and a second blade is fixedly mounted on the supporting structure of the feeding roller at such a position as to interfere with said first blade. Even in this case, although a simpler and more compact device is obtained, there is always the problem of the presence of a blade in an accessible and therefore potentially dangerous region when the user is manually performing the paper inserting operation on the feeding roller. Moreover, the contact between the two blades causes them to wear out and the effectiveness of the mechanism is strictly related to the prevention of the rising of plays that could reduce or cancel the interference between the blades. Examples of this type of mechanism are described in EP 693268 and EP 930039. 
     In order to overcome the problems of noisiness, safety, bulkiness and reliability of the above-described devices the most recently developed cutting mechanisms include a blade that is rotationally received within the feeding roller and acts with an oscillatory movement controlled by the rotation of said roller. Examples of this type of cutting mechanism are described in WO 2006/30138 and WO 2007/17603, both showing a blade-carrying shaft provided at one end thereof with a toothed sector that acts as a rack and during the rotation of the feeding roller periodically engages with a corresponding fixed toothed sector, formed on the roller supporting structure, that acts as a pinion. 
     In this way, the blade performs a partial rotation to come out of the roller during the cutting phase defined by the arc of engagement of the two toothed sectors and then rotates back inside the feeding roller under the action of a return spring when said toothed sectors disengage. Although this arrangement is effective from the points of view of safety and bulkiness, it still has drawbacks as to noisiness, reliability and smoothness of operation. 
     A first drawback stems from the fact that the engagement and disengagement of the toothed sectors at each operating cycle require a perfect synchronization of the rotation of the blade-carrying shaft and of the feeding roller to prevent jamming of the mechanism and an early wear of the first teeth that start the engagement. In fact, to this purpose, WO 2006/30138 provides for the rack and pinion to be provided with a pulley and for a belt to be always taut between said two pulleys to synchronize the movement thereof. This obviously implies a structure that is quite complicated, expensive and scarcely reliable since a slackening, slipping or wear of the belt is sufficient to negatively affect the smoothness of operation. 
     A second drawback resides in the noise caused by the blade returning to its rest position under the action of the return spring, and in this respect WO 2007/17603 provides for the rack and pinion to be provided with corresponding cam surfaces sliding on each other during the return run of the blade in order to slow it down and reduce the noise. Also this arrangement, however, implies a greater complexity of the mechanism which being also subjected to a sliding wear will end up over time in being noisy. 
     Still another drawback intrinsic to the periodical engagement of the toothed sectors, even in the condition of perfect efficiency of the mechanism, is given by the variation of the resistance of the mechanism in the different phases of the operating cycle which results in less smoothness of operation and in an inconvenience for the user. In fact when the user begins to pull on the projecting tip of paper he/she encounters a minimum resistance since the rack and pinion are not engaged, then the resistance increases upon engagement and then decreases again upon disengagement. 
     A similar cutting mechanism comprising a blade rotationally received within the feeding roller and acting with an oscillatory movement controlled by the rotation of said roller is disclosed also in EP 1153565A1 in the name of the same applicant. Also in this case, the blade performs a partial rotation to come out of the roller during the cutting phase and then rotates back inside the feeding roller under the action of a return spring, but the arc of operation of the blade rather than being defined by the arc of engagement of two toothed sectors like in the above-described mechanisms is defined by the angular extension of two curved reliefs internally formed on the sides of the feeding roller supporting structure. 
     More specifically, these reliefs act on a rod mounted on the feeding roller so as to be able to rotate and longitudinally slide with respect thereto, said rod being provided at a first end with a skid and at a second end with a toothed wheel that engages a fixed toothed wheel formed on the supporting structure at a position coaxial with the feeding roller. Due to this gearing and to said reliefs that extend along consecutive non-overlapping angular positions, the rotation of the feeding roller results in a constant rotation and a longitudinal reciprocating motion of the rod that slides to the left when its toothed wheel meets the relief adjacent to and coaxial with the fixed toothed wheel and then slides to the right when its skid meets the other relief on the opposite side. 
     The blade-carrying shaft is mounted on the feeding roller coaxial with said sliding rod and, at the end towards the fixed toothed wheel, rather than being provided with a toothed sector is provided with a first longitudinal pin that during the rotation of the feeding roller periodically engages with a corresponding second longitudinal pin formed on the toothed wheel of the sliding rod. This second pin draws into rotation the blade-carrying shaft causing the projection of the blade against the resistance of a return spring as long as said rod is positioned on the left, and then disengages from the first pin when the rod slides to the right. In this way, the sliding rod makes a complete rotation at each operating cycle whereas the blade-carrying shaft only performs the conventional oscillatory movement. 
     It is therefore clear that also this mechanism suffers the above-mentioned drawbacks of noisiness, possible pin wear, necessity for synchronization, variation of the resistance of the mechanism in the different phases of the operating cycle and a certain structural complexity that increases its cost and decreases its reliability. 
     FR 2828084 discloses another similar yet much more complicated mechanism in which the blade-carrying shaft is not mounted on the feeding roller but on a second roller adjacent thereto that is drawn into rotation by the feeding roller through an end gearing. A second toothed wheel of the feeding roller is further engaged with a toothed wheel rotationally mounted on the side of the supporting structure and provided with a cam which in turn engages another cam also rotationally mounted on the side of the supporting structure. Said second cam is provided with a third toothed wheel that engages in turn a fourth toothed wheel arranged at the end of the blade-carrying shaft, the oscillatory run of said shaft being limited by a projection formed at the opposite end of the shaft which abuts against a stop formed on the second roller. 
     Such a complicated mechanism is clearly quite expensive, scarcely reliable, noisy and particularly prone to problems of synchronization among all the several components that interact for its operation. 
     Finally, it should also be considered that a common drawback of the above-described four mechanisms where motion is transmitted through teeth is the presence of the toothed members only at one of the two ends of the mechanism, which inevitably implies an unbalance in the forces acting on the mechanism. Such an unbalance negatively affects the smoothness of operation especially when the user&#39;s pull is not centered. 
     Therefore the object of the present invention is to provide a feeding and cutting unit for a dispenser of paper towels which overcomes the above-mentioned drawbacks. 
     This object is achieved by means of a feeding and cutting unit in which the blade-carrying shaft received in the feeding roller is provided at least at one end, preferably at both ends, with a toothed wheel that acts as a rack and is constantly engaged with a corresponding fixed toothed wheel, formed on the supporting structure, that acts as a pinion. Other advantageous features are recited in the dependent claims. 
     A first important advantage of the present unit resides in the greater reliability and smoothness of operation guaranteed by the constant engagement of the rack and pinion, whereby there are no problems of synchronized rotation of the blade-carrying shaft and of the feeding roller regardless of plays or wear that might rise over time. In this way, moreover, the resistance of the mechanism in the different phases of the operating cycle is substantially constant, since the gearing is constantly engaged, and it requires a lower effort on the part of the user thanks to the greater smoothness of operation. 
     A second significant advantage of this unit consists in the elimination of the blade return spring, which results in a reduction of noise and a simplification of the unit that is cheaper. It should be noted that the simplification results also from being able to dispense with the belt transmission and the cam profiles described in the above-mentioned prior art. The saving is even more evident with respect to the prior art that provides for a still more complicated structure with a second roller for the blade-carrying shaft in addition to the feeding roller. 
     Another advantage of the present unit is given by its capacity to operate effectively also with paper having a weight higher than foreseen in that the cutting is carried out along the maximum possible arc of rotation of the feeding roller, and therefore for the maximum time, whereas in mechanisms with an oscillating blade a portion of the arc of rotation is taken up by the return run of the blade that may not have sufficient time to complete the cutting of a paper heavier than the paper for which the unit was designed. 
     Still a further advantage of said unit, in its preferred embodiment with a gearing at each end, derives from the symmetry of the stresses on the cutting mechanism even in case of off-center pull by the user, which results in a greater reliability and smoothness of operation. 
    
    
     
       These and other advantages and characteristics of the feeding and cutting unit according to the present invention will be clear to those skilled in the art from the following detailed description of an embodiment thereof, with reference to the annexed drawings wherein: 
         FIG. 1  is a perspective exploded view of the main components of the feeding and cutting unit; 
         FIG. 2  is a perspective view of the unit of  FIG. 1  in the assembled condition, yet without the components on the left and the front guard for the sake of clarity of the drawing; 
         FIG. 3  is a front view of the unit of  FIG. 1  in the assembled condition, yet without the front guard; 
         FIG. 4  is a right side elevational view of the unit of  FIG. 1  with a paper roll whose end tip passes through the unit and comes out below; 
         FIG. 5  is a front view similar to the preceding one; 
         FIG. 6  is a left side elevational view similar to the preceding one with the addition of the spring for completing the rotation; 
         FIG. 7  is a sectional view taken along line A-A of  FIG. 5  showing better the path of the paper band through the feeding and cutting unit; and 
         FIGS. 8-15  are diagrammatic views similar to the preceding one that illustrate an operating cycle. 
     
    
    
     Referring first to  FIGS. 1 to 5 , there is seen that the feeding and cutting unit for a dispenser of paper sheets according to the present invention substantially comprises a rear support element  1  with vertical end seats for the insertion of lateral shoulders left  2  and right  3  between which there is rotatably supported a feeding roller  4 , formed by two half-cylinders  4   a  and  4   b,  which in turn internally rotatably supports a shaft  5  parallel thereto which carries a serrated blade  6  which, during a part of the rotation of shaft  5 , protrudes through a corresponding longitudinal slot formed in roller  4  as better illustrated in the following. 
     The rotation of the blade-carrying shaft  5  is obtained as a result of the rotation of roller  4  by means of at least one end gearing, preferably two as shown in the figures, formed at least by a toothed wheel  7 , integral with and coaxial to shaft  5 , which engages a corresponding toothed wheel  8  formed on the inner side of the relevant left  2  and right  3  shoulder at a position coaxial with the axis of rotation of roller  4 . 
     A counter-pressure shaft  9  is also rotatably supported between shoulders  2 ,  3  with an axis of rotation parallel to the axis of rotation of the feeding roller  4  and in such a position as to be in contact with pre-load with the upper portion of the latter. Shoulders  2 ,  3  respectively carry on their outer sides a ratchet  10  and a manual loading knob  11  which are integral with respective opposite support pins of roller  4 . A front guard  12  is finally mounted on shoulders  2 ,  3  and is provided, preferably at a central position, with a rib  12   a  that fits into a corresponding groove formed on roller  4  so that the paper band is surely deviated outside the dispenser by said rib  12   a  whenever the band remains stuck on the feeding roller  4  even beyond the angular rotatory position corresponding to the outlet slot. 
     With reference also to  FIGS. 6 and 7 , there is seen that roller  4  can rotate only in the counter-clockwise direction (seen from the left) because the ratchet mechanism  10  located on the outer side of the left shoulder  2  is mounted so that the pawl  10   a  pivoted on said shoulder  2  prevents the clockwise rotation of the serrated wheel  10   b  integral with the left pin of roller  4 . Obviously, in another embodiment different from that illustrated the rotation might be only clockwise if this were necessary, it would suffice to reverse the arrangement of ratchet  10 . 
       FIG. 6  also shows a spring  13 , arranged between a peg of the serrated wheel  10   b  and a peg formed on shoulder  2 , which provides to complete the rotation of roller  4  so that the cutting results smooth and light being performed more by the strength of spring  13  than by the user&#39;s pull on the end tip L of roll R which protrudes downward from the dispenser. Furthermore, spring  13  ensures that an end tip L of the band protrudes from the dispenser for the next user. 
     As shown in the sectional view of  FIG. 7 , the paper band coming from roll R is first wound on the front of the counter-pressure shaft  9  then sandwiched between the latter and the feeding roller  4 , so as to pass on the back of roller  4  and to exit at the bottom through the slot between the latter and the rear support  1 . The blade-carrying shaft  5  rotates inside roller  4  around its own axis of rotation, which in turn rotates together with roller  4  around the axis of rotation of the latter so that blade  6  protrudes therefrom for about half a turn from the angular position shown in  FIG. 7 . 
     The simple and effective operation of the present device can be easily understood from the description above, as now illustrated with the aid of  FIGS. 8 to 15  in which the blade-carrying shaft  5  has been omitted to show more clearly how the rotation of blade  6  is due to the constant engagement of the toothed wheel  7  and of the toothed wheel  8  which form the end gearing. 
     For the loading of the device, the continuous paper band unwound from roll R is inserted from the front between the counter-pressure shaft  9  and roller  4  which is rotated by means of knob  11  until the end tip L comes out. When the user pulls tip L, this causes the rotation of roller  4  that carries shaft  5  whose toothed wheel  7  engaged with the toothed wheel  8  in turn causes the rotation of shaft  5  and therefore of blade  6 . 
     From the rest position of  FIG. 8  in which blade  6  is located on the front of roller  4  (three o&#39;clock position) and is directed inside the latter, in the first phase of the operating cycle the simultaneous rotation of roller  4  and shaft  5  carried thereon leads to the position of  FIG. 11 , substantially coinciding with  FIG. 7 , in which blade  6  is located just beyond the top of roller  4  (eleven o&#39;clock position) and begins to protrude through the longitudinal slot of the latter. 
     The cutting of the paper band takes place along about a quarter of a turn in the second phase of the operating cycle between the position of  FIG. 11  and the position of  FIG. 13 , in which blade  6  is located just below the back of roller  4  (eight o&#39;clock position) and projects substantially perpendicular from it. At this point, usually, the end tip L has already been cut from the rest of the band so as to form a towel T available to the user. However, in the case of paper more resistant to cutting, the detachment of towel T can also occur further downstream of the position of  FIG. 13  since blade  6  continues to exert its cutting action until the band arrives out of the reach of blade  6  moving away from roller  4 . 
     In the third phase of the operating cycle of the unit, with the aid of spring  13  as illustrated above, roller  4  and blade  6  complete their rotation to return to the rest position of  FIG. 8  passing through the positions illustrated in  FIGS. 14 and 15 . The presence of ratchet  10  prevents any reverse rotation of roller  4  at the end of the rotation under the thrust of spring  13 , thus ensuring the projection of the end tip L for the fraction by the next user. 
     It is clear that the embodiment of the feeding and cutting unit according to the invention described and illustrated above is just an example susceptible of various modifications. In particular, to obtain a greater “aggressiveness” of the cut by having blade  6  come out from roller  4  in the direction opposite to the direction of advancement of the paper band (i.e. clockwise in the example shown), the end gearing could also include a third toothed wheel interposed between the toothed wheels  7 ,  8  and also carried by roller  4  so as to reverse the rotation of the blade-carrying shaft  5 . 
     Similarly, if the overall gear ratio between the toothed wheel  7  and the toothed wheel  8  is different from the 1:1 ratio of the illustrated embodiment, other variations are possible. For example, if shaft  5  performs only half a turn at every rotation of roller  4  (1:2 ratio) there might be two opposing blades  6  along the circumference of shaft  5 , or you could dispense a towel T of double length if blade  6  is always single.