Patent Publication Number: US-2011062653-A1

Title: Media stocker and paper feeder

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2009-213833, filed on Sep. 15, 2009, the entire content of which is incorporated herein by reference. 
     FIELD 
     Embodiments described herein relates generally to a media stocker for stacking and holding a recording medium to be fed into a paper feed opening of an image forming apparatus, the media stocker provided integrally with or separately from the image forming apparatus, a paper feeder using the media stocker, and a method for controlling the configuration of a recording medium stacked and held in the media stocker or the paper feeder. 
     BACKGROUND 
     A media stocker vertically elevates a feeder plate to allow a large number of recording media to abut against a pickup roller. In this construction, the media stocker may stock a number of recording media, for example, several hundred pieces. 
     As such, since the media stocker stocks a large number of recording media, a large force is applied to the feeder plate. For this reason, an elevating device for vertically elevating a feeder plate generally supports the feeder plate by holding both sides of the feeder plate, which are the upstream side and the downstream side in the direction of conveying a recording medium. 
     However, when a feeder plate is supported by holding both sides of the feeder plate, i.e., the upstream side and the downstream side in the direction of conveying a recording medium, a whole device becomes large-scaled and complicated in structure. Accordingly, in one embodiment, a media stocker has a feeder plate supported by holding one side of the feeder plate, i.e., a cantilever-supported feeder plate, as shown in  FIG. 4 . 
     In  FIG. 4 , A denotes a feeder plate which may elevate, and M denotes recording media. Elevating device E elevates feeder plate A to press recording media M against pickup roller PU. Pickup roller PU picks up to convey the uppermost of recording media M. At this point, separating device S separates only the uppermost of recording media M from the lower recording media. 
     As the number of recording media M stacked and held on feeder plate A increases, the weight of recording media M increases. Thus, in the construction of the media stocker, a free end of feeder plate A is inclined downwardly, as shown in  FIG. 4 . Consequently, the uppermost of recording media M stacked and held on the feeder plate is inclined to have a high position at the downstream side in the conveying direction. 
     However, in the related field to the media stocker, it is generally known that the desired configuration of the uppermost recording medium at the pickup position of a pickup roller is to remain level. If the uppermost of recording media M is inclined, the direction of picking up recording media M at pickup roller PU is also inclined, as shown in  FIG. 4 . Therefore, separation trouble may occur at separating device S, so as to cause a conveying failure. For example, the separation trouble at separating device S may cause a situation where the uppermost portion of recording media M cannot be properly separated, or skewing may occur in the structure of separating device S. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a front view. 
         FIG. 2  illustrates a perspective view showing a feeder plate and an elevating device viewed from an image forming apparatus side. 
         FIG. 3  illustrates a front view showing a feeder plate and an elevating device. 
         FIG. 4  illustrates a front view showing an example of a paper feeder in the related art. 
     
    
    
     DETAILED DESCRIPTION 
     According to an embodiment, a media stocker includes a feeder plate configured to maintain a plurality of recording media in a stacked state thereon, a vertically elevating device configured to cantilever-support the feeder plate, and a guide member disposed vertically to face a free end of the feeder plate and configured to guide the recording media stacked on the feeder plate. And the media stocker includes a roller attached to the free end side of the feeder plate and rotatable around a horizontal shaft, the outer circumferential surface of the roller being in contact with the guide member at a position higher than the position of the uppermost support point of the feeder plate by the elevating device. 
     Now, an exemplary embodiment will be hereinafter described in detail with reference to  FIGS. 1 to 3 .  FIG. 1  is an entire front view. In one embodiment, paper feeder  31  includes media stocker  101  combined with pickup roller  41  and a separating device  51 . Paper feeder  31 , for example, stocks recording media M in media stocker  101 . Pickup roller  41  picks up to convey the uppermost of recording media M in the media stocker. Separating device  51  separates the uppermost of recording media M from other recording media to feed the uppermost to a paper feed opening of an image forming apparatus (not shown). 
     Separating device  51  includes conveying roller  52  and separating roller  53  with feeding path SP of recording media M interposed therebetween. Conveying roller  52  is installed above feeding path SP and separating roller  53  is installed below feeding path SP. When pickup roller  41  begins to rotate for picking up to convey the uppermost of recording media M, conveying roller  52  rotates to apply conveying force to the picked one of recording media M. Separating roller  53  rotates together when conveying roller  52  begins to rotate. When the picked one of recording media M reaches a position just ahead of separating device  51 , separating roller  53  pauses to rotate. However, at this point, as well as the uppermost of recording media M, other recording media of recording media M that are positioned below the uppermost are frictionally conveyed to separating device  51  by the pick-up and conveyance of pickup roller  41 . In this respect, separating roller  53  pauses to rotate just before the picked one of recording media M reaches separating device  51 , thereby other recording media positioned below the uppermost hit against separating roller  53  may be blocked. Then, only the uppermost of recording media M is separated from other recording media, and is conveyed to conveying roller  52  so as to be fed into a paper feed opening (not shown) of an image forming apparatus. In this case, a conveying force applied to the uppermost of recording media M by the rotation of conveying roller  52  is larger than a frictional force between the uppermost of recording media M and the blocked other recording media positioned just below the uppermost. Consequently, a plurality of recording media M picked up by pickup roller  41  are processed by separating device  51  so that only the uppermost of recording media M is separated to be fed. 
     In this respect, the pause of the rotation of separating roller  53  is performed by a one-way clutch (not shown). In addition, for example, whether the picked one of recording media M reaches a position just ahead of separating device  51  is determined by using a sensor  61  disposed between pickup roller  41  and separating device  51 . In one embodiment, the sensor  61  may be a transmission type sensor, but not limited. 
     Moreover, separating device  51  is not limited the type as described above. For example, separating device  51  may be a reverse roller type. 
     Next, media stocker  101  is described. Media stocker  101  has feeder plate  103  attached to a sheet of base template  102  with feeder plate  103  being capable of elevating. Feeder plate  103  is cantilever-supported by base template  102  and is capable of elevating. Feeder plate  103  has a free end FE at a side opposite to the cantilever-supported side. Elevating device  104  elevates feeder plate  103 . Thus, feeder plate  103  will be described after elevating device  104  is described. 
       FIG. 2  is a perspective view of feeder plate  103  and elevating device  104  viewed from an image forming apparatus aside.  FIG. 3  is a front view of feeder plate  103  and elevating device  104  according to an exemplary embodiment. Elevating device  104  includes a pair of opposing elevating rollers  105  attached to a lower portion of feeder plate  103  to share a common horizontal line with rotatable around its horizontal shaft, and a pair of opposing rear-surface elevating rollers  106  opposite to feeder plate  103  with base template  102  interposed therebetween. The pair of opposing rear-surface elevating rollers  106  is mounted to single roller holding member  107  to share a common horizontal line with rotatable around its horizontal turning shaft. Also, base template  102  has three connecting holes  108  vertically extended with an elongated slot shape so that feeder plate  103  and roller holding member  107  are connected with each other through connecting holes  108 . Thus, feeder plate  103  may elevate along base template  102  while being supported by opposing elevating roller pair  105  disposed on the front surface of base template  102  and opposing rear-surface elevating roller pair  106  disposed on the rear surface of base template  102 . From the perspective of a support point where feeder plate  103  is supported, a portion where elevating roller pair  105  abut against base template  102  is support point LP positioned at the lowermost position, and a portion where rear-surface elevating roller pair  106  abut against base template  102  is support point UP positioned at the uppermost position (see  FIG. 3 ). 
     In addition, elevating device  104  includes a pair of belt winding devices  109  disposed at both sides of base template  102 . Each of belt winding devices  109  has endless belt  111  stretched between a pair of upper and lower pulleys  110 . The lower pulley receives rotary force from a driving source (not shown) to rotate, which causes endless belt  111  to turn. In this respect, elevating device  104  has connecting section  112  provided on roller holding member  107  with connected to each of endless belts  111 . Thereby, rotary force of endless belts  111  is transmitted to roller holding member  107  to elevate feeder plate  103 . 
     As shown in  FIGS. 1 to 3 , media stocker  101  includes guide member  113  disposed vertically to face a free end of the feeder plate. Guide member  113  guides recording media M stacked on the feeder plate. Guide member  113  is attached to pivoting support member  116 , and is pivotable about its horizontal shaft. Pivoting support member  116  is fixed to stud  115  mounted uprightly on bottom frame  114  of media stocker  101 . Since guide member  113  is pivotable around its horizontal shaft, it may be opened to expose a space for receiving and dispensing recording media M with respect to feeder plate  103 . An upper end of guide member  113  is detachable to a frame (not shown) of media stocker  101 . 
     Bottom frame  114  of media stocker  101  also supports base template  102  to secure rigidity together with other frames of media stocker  101 . Accordingly, bottom frame  114  and guide member  113  fixed at the upper end implement a strong and firm structure with rigidity. 
     Feeder plate  103  will now be described hereinafter. Feeder plate  103  includes roller  117  attached to free end FE. Roller  117  is rotatable around roller shaft  118 , which is arranged horizontally, so as to be in contact with guide member  113 . As shown in  FIG. 3 , roller  117  is in contact with guide member  113  at a position higher than the position where opposing rear-surface elevating roller pair  106  abut against base template  102 . As described above, from perspective of a support point where feeder plate  103  is supported, a portion where rear-surface elevating roller pair  106  abut against base template  102  is support point UP positioned at the uppermost position. Thus, contact position CP where roller  117  attached to free end FE of feeder plate  103  abuts against guide member  113  is positioned higher than the position of the uppermost support point UP of feeder plate  103  by elevating device  104 . 
     The outer circumferential surface of roller  117  is disposed to be in contact with guide member  113 . In this respect, the contact between roller  117  and guide member  113  may be a constant contact or temporary contact which occurs when a stack of recording media M are loaded on feeder plate  103 . In other words, roller  117  may be slightly separated from guide member  113  when recording media M are not loaded on feeder plate  103 , and may be in contact with guide member  113  when recording media M are loaded on feeder plate  103  to make feeder plate  103  inclined downwardly due to its weight. In this case, roller  117  may be in contact with guide member  113  when at least a predetermined maximum number of recording media M should be loaded on feeder plate  103 . 
     From the foregoing, as shown in  FIG. 3 , a triangle is formed by the uppermost support point UP of feeder plate  103  where rear-surface elevating roller pair  106  abut against base template  102 , the lowermost support point LP of feeder plate  103  where elevating roller pair  105  abut against base template  102 , and contact position CP where roller  117  abuts against guide member  113 . In this case, the triangle is an obtuse angled triangle in which an angle formed by a side between support point LP and support point UP and a side between support point UP and contact position CP is an obtuse angle. 
     Under such a construction, media stocker  101  stocks and stores a large number of recording media M so as to prepare for the pickup and conveyance of recording media M by pickup roller  41 . Recording media M are placed on feeder plate  103  for stock. As such, a plurality of recording media M are stacked and stored by feeder plate  103 , which may elevate recording media M. 
     Subsequently, as the number of the stacked recording media M increases, free end FE of feeder plate  103  may be inclined downwardly due to the weight of recording media M. At this point, a turning trajectory according to the downwardly inclining movement of free end FE is convex outwardly from a vertical plane including free end FE at its initial position. This is because the triangle formed by support point UP, support point LP and contact position CP has an obtuse angle formed by a side between support point LP and support point UP and a side between support point UP and contact position CP. Accordingly, roller  117  abuts against guide member  113  so that free end FE of feeder plate  103  can be prevented from being inclined downwardly. 
     In this respect, when free end FE of feeder plate  103  starts to be inclined downwardly due to the weight of the plurality of recording media M stacked and held on the feeder plate, guide member  113  supports the position where a turning trajectory according to the downwardly inclining movement of free end FE is convex outwardly from a vertical plane including free end FE at its initial position. 
     As described above, according to the exemplary embodiment, since the downwardly inclining movement of feeder plate  103  is prevented by guide member  113 , although feeder plate  103  is cantilevered, the configuration of the uppermost of recording media M stacked on feeder plate  103  can be maintained level. As a result of maintaining level the configuration of the uppermost of recording media M, pickup roller  41  pick up and convey recording media M with maintaining level, so that separating device  51  may separate and feed without causing problems. Accordingly, a failure in conveying recording media M can be prevented. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel media stocker, paper feeder using the media stocker, and method for controlling the configuration of a recording medium described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the media stocker, the paper feeder using the media stocker, and the method for controlling the configuration of a recording medium described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.