Patent Publication Number: US-2022227592-A1

Title: Peripheral device with gear train protection

Description:
BACKGROUND 
     Present examples relate to a peripheral device which utilizes a gear train, for non-limiting example, a printing peripheral device. More specifically, but without limitation, present examples relate to a mechanism or assembly which protects the gear train during operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Examples are described in further detail below, with reference to the drawings, in which: 
         FIG. 1  is a schematic side section view of a peripheral device; 
         FIG. 2  is a schematic view of a gear train and motor; 
         FIG. 3  is an exploded perspective view of a shaft and gear couple; 
         FIG. 4  is a side section view of the protection mechanism during rotation in a first direction; and, 
         FIG. 5  is a side section view of the protection mechanism during rotation in a second direction. 
     
    
    
     DETAILED DESCRIPTION 
     During the print process, end users sometimes pull on the media as it is indexing out of the peripheral device. When an end user pulls on the media, an external force or torque may be applied to the gear train and motor. Over time, or in severe instances, this external force or torque can result in damage to a gear train which controls indexing of the media through the peripheral. Accordingly, these forces may be transmitted through the gear train to the motor to cause damage to, and have negative impact on the wear life, of either or both of the gear train and motor. The present examples provide a gear assembly which will disengage when such external force or torque is applied so as to limit the transmittal of such through the gear train and to the motor. 
     Referring now to  FIGS. 1-5 , a gear train assembly for a media feeding peripheral device is provided. The gear train provides protection of the gear train and motor from external force applied during operation. More specifically, the gear train allows for opening, or disconnection, of the mechanical communication between the gear train and a shaft when an external force is applied to the system. This disconnect of the mechanical communication through a transmission decreases the likelihood of damage to the gear train or the motor by the external force, such as, for example, an end user pulling on the media being indexed or passed through the peripheral for printing, for example. 
     Referring now to  FIG. 1 , a schematic side section view of a peripheral is depicted. The peripheral device may be embodied as a printer, according to some examples, but such description is merely an example and should not be limiting. For example, other peripheral devices may include external finishers that process printed media. The gear train may be used with various devices. The peripheral device  10  that includes a housing  12  and print mechanism  14  which is located within the housing  12 . The print mechanism  14  may be, for non-limiting example, a dot-matrix print mechanism, an ink jet print mechanism, or a laser print mechanism. This list is non-exhaustive as other print mechanisms and other devices having motors and gears may be utilized and be within the scope of the instant teaching. 
     The peripheral device  10  also comprises a gear train  24  which may be utilized to move the print media  16  through the housing  12 . The print media  16  may move through a media path  18  which is defined by a media input  19  for the print media  16 , a media output  20 , and a path therebetween. The gear train  24  rotates in response to rotation of the motor  22  to effectuate movement of the print media  16  through the peripheral. As the print media  16  moves through the housing  12  and is indexed by the gear train  24  and the motor  22 , the print media  16  is printed upon to form an image, document, or other desirable print output. The print media  16  may be paper stock, photo media, or any of various materials which may be passed through the peripheral to receive ink or laser toner. The motor  22  may be, but is not limited to, in some examples a stepper motor, and may be fixed in relation to a frame (not shown) within the housing  12  by a fixation component, such as a screw which may engage the frame. The motor  22  receives power via a power input (not shown) to drive the gear train  24 . The power input may be an electrical power input or a mechanical power input. In some examples, the motor  22  may be an electric A/C or D/C motor. 
     Near the media output  20 , a hand H is shown grasping the media  16  and a force F is applied to the print media  16  to pull such from the peripheral device  10 . As depicted, the print media  16  is still engaging the gear train  24  and indirectly the motor  22 . The instant examples serve to protect the gear train  24  and the motor  22  from this application of external force. 
     As previously noted, this may be detrimental to the longevity of gear trains and/or the motors in prior art systems. Accordingly, the present examples open or disengage the gear train  24  in a manner such that external force F applied by the end user, as depicted in  FIG. 1 , is not transmitted through the entirety of the gear train  24  and the motor  22 . 
     In the side section view, one can glean that when the sheet is pulled by a user, the torque applied to the gear train  24  increases torque direction applied between those gears as opposed when the motor  22  is driving the gear train  24 , even when the media is moving in the same direction through the peripheral device  10 . When the motor  22  is driving the print media  16  forward along media path  18 , the torque applied to the roller gear  52  ( FIG. 2 ) against a second gear  54  is maintained to keep the gear train  24  closed or engaged. However when the additional external force F of pulling of the print media  16  is applied, the gear train  24  disconnects or separates to inhibit damage to the gear train  24  and/or motor  22 . 
     Referring now to  FIG. 2  is a schematic view of the gear train  24  and motor  22  is provided and additionally includes a shaft  40  and rubber roller  42 . The motor  22  is shown positioned adjacent to and mechanically engaging the gear train  24 . The gear train  24  may include a pinion  26  and gears  28 , which drive rotation of the shaft  40  and rubber roller  42 . The gear train  24  may include a number of gears some of which may in some examples define subassemblies or carriers of gears in order to provide the transmission between the motor  22  and the rubber roller  42  and shaft  40 . It should be understood that the gear train  24  may take various forms and is not limited by number or arrangement of gears. Each of the gears may have a plurality of teeth and any of the gears may be composite or non-composite gears. The various types of gears may include, but are not limited to, spur, helical, face, double helical, rack and pinion, bevel, miter, worm, screw gear and internal gears. Some of the gears may also be housed within a housing if desirable. 
     The gear train  24  may comprise a gear couple  50  which may engage one another for rotation in one driving direction but which mechanically disengage from one another when an external force is applied to drive rotation in the opposite direction. As depicted, the gear couple  50  may comprise a roller gear  52  and a second gear  54  that causes the disengagement of the roller gear  52  in one direction. The rubber roller  42  may be connected to one of the first and second gears  52 ,  54  and in the instant example, is located on the shaft  40  and adjacent to the second gear  54 . In other examples, the gear couple  50  may be located at other locations along the gear train  24 , and therefore is not limited to positioning at the rubber roller  42 . The rubber roller  42  engages the print media  16  ( FIG. 1 ) during indexing or driving of the print media  16  through the peripheral device  10 , and is engaged with the print media  16  when the scenario occurs that an end user grasps and pulls the print media  16  while the gear train  24  and motor  22  are still operating and engaged with the print media  16  passing through the housing  12  ( FIG. 1 ). While the gear couple  50  is shown located along the roller shaft  40 , it should be understood that the gear couple  50  may be located at various positions within the gear train  24 . 
     Further, as will become clear with further reading, the roller gear  52  and the second gear  54  are shown in an exaggerated separated state in  FIG. 2 . The exaggeration is merely for sake of understanding that the two gears  52 ,  54  disconnect from one another when the external force is applied. In the instant example, the separation of gears  52 ,  54  is a lateral separation. Further in some examples, the roller gear  52  may move away laterally from the second gear  54 , while in other examples, the second gear  54  may move away from the roller gear  52 . Still further, one skilled in the art should recognize that other gears in the gear train  28  may provide the protection of separation. 
     Referring now to  FIG. 3 , an exploded perspective view of an example roller gear  52  and a rubber roller  42  are shown for ease of description separate of the remaining gear train  24  ( FIG. 2 ). The rubber roller  42  is shown disposed on the shaft  40 . The roller gear  52  and the second gear  54  are exploded but when assembled are capable of engaging one another so that the roller gear  52  drives rotation of the second gear  54 , the roller shaft  40  and the rubber roller  42 . The shaft  40 , according to some examples, may be a metallic shaft and the rubber roller  42  may be formed integrally during manufacture of the shaft  40 , for example, by molding the rubber roller  42  onto the shaft  40 . The term “rubber roller” may comprise various rubber or rubber based materials, plastic materials, or other materials which have some ability to frictionally engage media to drive movement or indexing of print media  16  through a peripheral device. Also depicted on the shaft  40  and adjacent to the rubber roller  42 , is the second gear  54  which may be also formed of a rubber or plastic material and engages the roller gear  52 . The second gear  54  rotates with the rubber roller  42  during operation by the motor  22  ( FIG. 1 ) or when an end user pulls the print media  16  during operation. The second gear  54  may include teeth  56  which may in some examples extend from a sidewall of the second gear  54 . Further, in some examples, the gear teeth  56  may be asymmetrical such that on one side a first driving surface  57  is presented for engagement with the roller gear  52  in order to drive rotation of the shaft  40  and the rubber roller  42 . The teeth  56  may also comprise a second surface  59  that may be presented to the roller gear  52  which is angled, tapered, or otherwise formed to provide a lateral force or a lateral component force and movement of the roller gear  52  and cause disengagement of the roller gear  52  and the second gear  54 , or alternatively movement of the second gear  54  away from the roller gear  52 . 
     The second gear  54  of the gear couple  50  may be generally circular in cross section and provides the asymmetric teeth  56  on a side surface  58  of the second gear  54  closest to the roller gear  52 . The second gear  54  may also be in the form of a collar having a hollow central interior area  55  such that a hub  53  of the roller gear  52  may pass into a hollow area of the second gear  54 . As shown in this view, the roller gear  52  and the second gear  54  are coaxial and the roller gear  52  is formed as to allow for lateral movement of the roller gear  52  relative to the shaft  40 . The hollow central interior area also allows for close proximity and engagement of the gears  52 ,  54 . 
     The roller gear  52  may have a plurality of tooth engagement apertures  60  wherein the asymmetric teeth  56  may be positioned. The teeth  56  are positioned in the tooth engagement apertures  60  for engagement by the teeth  56  when the roller gear  52  and the second gear  54  are engaged. When the two gears  52 ,  54  open or disconnect, the teeth  56  are no longer positioned in the tooth engagement apertures  60 . 
     The view also depicts the engagement of the teeth  56  with the apertures to drive rotation of the second gear  54 , shaft  40  and rubber roller  42 . The arrangement of the teeth  56  and tooth engagement apertures  60  provides that the first presented surface  57  of the asymmetric teeth  56  drives rotation of the second gear  54 . With rotation of gear  52  in a second direction, the second surface  59  of the asymmetric teeth  56  is presented to an edge of the tooth engagement aperture  60 , which causes lateral movement of the gear  52  along the shaft  40 . The second surface  59  may be angled, tapered, rounded or any of various shapes which cause a lateral force upon engagement by the roller gear  52 . 
     The roller gear  52  may also comprise a plurality of teeth  66  extending about the circumferential surface  68  of the roller gear  52 . The teeth  66  allow for engagement with the remainder of the gear train  28  ( FIG. 2 ). 
     Adjacent to the roller gear  52  is a bias element  70  which may in some examples be in the form of a pressure spring. The bias element  70  forces the roller gear  52  into engagement with the second gear  54  when the teeth  66  are aligned with the tooth engagement apertures  60 . The bias element  70  is also elastic which allows for the roller gear  52  to move toward the bias element  70  but force the roller gear  52  back toward its engaged position with the second gear  54 . In a normal operating condition, the bias element  70  applies a pressure to the roller gear  52  and forces it toward the second gear  54 . In some examples, the bias element  70  may be a compressed spring which pushes the roller gear  52  toward the second gear  54 . In other examples, the bias element  70  may be a stretched or tensioned spring placed at the second gear  54  to pull the roller gear  52  toward the second gear  54 . In some examples, the direction of bias force and the spring movement will be depend on which gear of a gear couple is moving away from the other. Further, other structures beyond springs may be utilized to bias the roller and gears  52 ,  54  into engagement when the teeth  66  and the tooth engagement apertures  60  are indexed appropriately. 
     A retaining clip, or other retention mechanism  72  is shown adjacent to the spring  70 . The retention mechanism  72  may engage the shaft  40  to retain the spring  70  and the roller gear  52  on the shaft  40  inhibiting lateral movement beyond a certain preselected allowance or amount of lateral movement. In the instant examples a keyway  74  is provided on the shaft  40  at which location the retention mechanism  72  may be disposed and allows for stationary location of the retention mechanism  72  against which the pressure spring  70  may be biased. In other examples, the keyway  74  may take the form of a hole extending through the shaft  40  and a clip which extends into the hole. In stiff further examples the retaining mechanism may be adhered, formed integrally or otherwise fixed on the shaft  40  to function as a retaining structure. 
     Referring now to  FIG. 4 , a side section schematic view of the engagement between the roller gear  52  and the second gear  54  is depicted. The asymmetric teeth  56  are in the form of a wedge shape which has the first surface  57  that engages the roller gear  52  when the roller gear  52  is driving motion of the second gear  54  and rubber roller  42 . The second surface  59  may be angled such that when the second surface  59  is presented to the roller gear  52 , the roller gear  52  is forced to move laterally (to the left in the depicted figure), as shown in broken line. Once the roller gear  52  is indexed to the next subsequent asymmetric tooth  56 , the roller gear  52  is forced by the bias element  70  back to engagement with the second gear  54 , which is to the position shown in solid line. 
     With reference now to  FIG. 5 , the roller gear  52  and the second gear  54  are again shown. The figure depicted two directions of rotation represented by semicircular arrows. In one direction of rotation of the roller gear  52 , the left most arrow, the operational direction of the gear train  28  ( FIG. 1 ) causes movement the movement of the roller gear  52  may cause movement of the second gear  54 . However, the second arrow, the right semicircular arrow, shows a net direction of rotation of the roller gear  52  due to the rotation of the rubber roller  42  faster than the normal rotation of the roller gear  52 . Alternatively, due to the applied force of pulling the media by an end user, the second gear  54  and the roller gear  52  are rotated due to the external force or torque rather than by the gear train  28  ( FIG. 1 ). The surface  59  of the second gear  54  engages the roller gear  52  and forces the roller gear  52  to move laterally, to the left in the instant figure. It should be further understood that the direction of rotation may be determined in two manners. In normal operation, the direction of rotation is controlled by the gear train and the rotation direction of the roller gear  52 . The normal direction of rotation causes the surface  57  of the roller gear  52  to engage and drive rotation of the second gear  54  and the rubber roller  42 . The alternate direction, however, may be caused by the user grasping the media, which is engaged to the rubber roller  42  during operation, and causes the second gear  54  to move faster than the roller gear  54 . When this occurs, the edge of the tooth engagement aperture  60  engages the surface  59  of the teeth  66  so that the roller gear  52  moves laterally. With this lateral movement, the gear train  24  disengages from the shaft  40  and rubber roller  42 . However, the bias element  70 , for example a spring, also biases roller gear  52  in the opposite direction toward the second gear  54 . With continued rotation of the roller gear  52  via the motor  22 , the roller gear  52  indexes the tooth engagement apertures  60  to reengage the asymmetric teeth  66  when aligned. 
     While the foregoing is directed to the various examples described, other and further examples may be devised without departing from the basic scope of the claims that follow. For example, the present examples contemplate that any of the features shown in any of the examples described herein, or incorporated by reference herein, may be incorporated with any of the features shown in any of the other examples described herein, or incorporated by reference herein, and still fall within the scope of the present claims.