Abstract:
The present invention provides an automatic paper feed apparatus which can reliably prevent papers from being discharged in an overlapped state in spite of simple construction. The automatic paper feed apparatus comprises a paper feed roller for automatically feeding a plurality of papers in order from an uppermost one, with the plurality of papers being contained in a cassette in a stacked state. A holding member having flexibility is provided so that the holding member comes into contact with the uppermost paper to generate a friction force that is weaker than that between the paper feed roller and the uppermost paper.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to an automatic paper feed apparatus for paper, especially medicine bag. 
   Conventionally, an automatic paper feed apparatus having, for example, following construction has been known. 
   Japanese Laid-open patent publication No. 49-67620 discloses an automatic paper feed apparatus in which a brake piece is provided on one end portion of copy papers stacked on the paper feed table to prevent the two copy papers from being conveyed at a time. 
   Japanese Laid-open patent publication No. 58-69645 discloses an automatic paper feed apparatus in which plates are interposed between stacked papers. The friction coefficient between each plate and paper is smaller than that between papers, preventing the papers from being fed in an overlapped state. 
   In the former automatic paper feed apparatus, the brake piece have to be provided on each copy paper. In addition, a solenoid and so on is necessary to lift the brake piece so that the copy papers can be discharged from the paper feed table one by one. Thus, there has been a disadvantage that it complicates the construction and invites cost up. 
   On the other hand, in the latter automatic paper feed apparatus, a complicated operation for interposing the plate between papers has been necessary. 
   SUMMARY OF THE INVENTION 
   An object of the invention is to provide an automatic paper feed apparatus which can reliably prevent papers from being discharged in an overlapped state in spite of simple construction. 
   In order to achieve the object, the present invention provides an automatic paper feed apparatus comprising a paper feed roller for automatically feeding a plurality of papers in order from uppermost one, the plurality of papers being contained in a cassette in a stacked state, wherein a holding member having flexibility is provided so that the holding member comes into contact with the paper to generate a friction force weaker than that between the paper feed roller and the paper. 
   According to the above construction, when the paper positioned uppermost is conveyed by the paper feed roller, the holding member also comes into contact with the next paper to generate a friction force, preventing the next paper from being conveyed together with the uppermost paper. As the holding member has a flexibility itself, it surely comes into close contact with the paper along the surface of the paper and generates a uniform friction force, properly preventing any trouble of paper feed caused by the paper feed roller. 
   Preferably, an engagement portion is formed on the rear end portion of the holding member, and wherein the engagement member is engaged with the cassette, whereby the holding member is attached on the cassette slidably with respect to a paper feed direction. In this case, the engagement member may be engaged with a guide portion which is provided in the cassette to guide the rear end of the paper. 
   According to the above construction, when the paper feed roller rotates, the paper positioned uppermost commences moving due to a friction force between the paper and the paper feed roller. Since the uppermost paper moves together with the holding member put thereon, it is possible to generate a proper friction force between the paper feed roller and the paper. Therefore, smooth conveyance of the paper is made possible. 
   Even if the paper is a medicine bag and has a different thickness by location, the holding member becomes deformed along the surface of the medicine bags and the friction force to be generated becomes uniform, allowing the medicine bag to convey smoothly. 
   Preferably, the holding member has a sheet-like shape, and wherein conductive layers comprising different material are formed on the top and bottom surfaces of the holding member. Thus, it is possible to select any proper one of top and bottom faces based on difference of paper and have such face come into contact with the paper. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further objects and advantages of the present invention will become clear from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, in which: 
       FIG. 1  is a side view of a medicine bag printing apparatus according to an embodiment of the present invention; 
       FIG. 2  is a front view of the medicine bag printing apparatus of  FIG. 1 ; 
       FIG. 3  is a perspective view showing a medicine bag in a state before completion as an example of the paper; 
       FIG. 4  is a front sectional view of a cassette mounted on the medicine bag printing apparatus of  FIGS. 1 and 2 ; 
       FIG. 5  is a side sectional view of the cassette of  FIG. 4 ; 
       FIG. 6  is a partly enlarged view of  FIG. 5 ; 
       FIG. 7  is a perspective view of the flexible sheet of  FIGS. 4 and 5 ; and 
       FIG. 8  is an enlarged sectional view of the flexible sheet of  FIG. 6 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Hereinbelow, embodiments of the invention will be described with reference to the accompanying drawings. 
     FIGS. 1 and 2  show a medicine bag printing apparatus according to an embodiment of the present invention. The medicine bag printing apparatus comprising an automatic paper feed apparatus  1  and a printing apparatus  3  for conducting a predetermined print on a paper  2  fed from the automatic paper feed apparatus  1 . In this embodiment, a medicine bag (refer to  FIG. 3 ) of which both side edges are stuck and become thick is used as a paper  2 . 
   In the automatic paper feed apparatus  1 , a cassettes  5  can be mounted into and dismounted from each of housing spaces  4  formed in multistage in a vertical direction. As shown in  FIG. 5 , in each housing space  4  is provided a paper feed roller  6  which is driven to rotate by drive means such as motor not shown. The paper feed roller  6  comes into contact with the paper  2  contained in the cassette  5  and positioned uppermost so that the paper  2  is conveyed and fed due to a friction force generated between both. (Hereinafter, a direction in which the paper is fed is referred to as “front” and a reverse direction thereof is referred to as “rear”.) 
   The cassette  5  has a box like shape with an upper surface opened as shown in  FIGS. 4 and 5 . On the front end face of the cassette  5  is formed an engagement recess  7  with which fingers of an operator are engaged when the cassette  5  is drawn from the housing space  4 . On the bottom of the cassette  5 , a support plate  20  is provided pivotably around a support shaft  10  via arms  1 l. The flat portion  8  of the support plate  20  positioned on the front end side is urged upward by a spring  9 . On the support plate  20 , guide plates  12  are slidably provided in a width direction to guide the both side edges of the paper  2  contained in the cassette  5 . On the upper face of the flat portion  8  of the support plate  20 , guide protrusions  13  are formed to support a middle portion of the medicine bag, i.e., a thinner portion than the side edge portions. On the bottom of the cassette  5  on the rear side, a guide piece  14  is slidably provided in the paper feed direction to guide the rear end of the paper  2 . on the upper end of the guide piece  14  is formed an engagement craw  15  protruding toward the front side. 
   In the cassette  5 , the same size of papers  2  are contained in a stacked state. (The size of papers  2  contained in each of the cassettes  5  is same in one case but different in another case.) The papers  2  are sandwiched between the support plate  20  urged upward by the spring  9  and the paper feed roller  6  in a state that the cassette  5  is mounted in the housing space  4 . 
   On the rear side of the paper feed roller  6 , a flexible sheet  16  as an example of the holding member of the present invention is put on the paper  2  contained in the cassette  5 . The flexible sheet  16  as shown in  FIG. 7  is made of urethane rubber, silicon rubber and so on. The flexible sheet  16  comes into close contact with the paper  2  in an area except a portion pressed by the paper feed roller  6 . on the rear end of the flexible sheet  16  is integrally formed an attachment piece  17  that is made of metal material such as stainless steel and has a rectangular shape. In the attachment piece  17  is formed a rectangular engagement hole  18  into which the guide piece  14  is inserted so that the flexible sheet  16  is slidably attached in the paper feed direction of the paper  2 . 
   In the medicine bag printing apparatus of above construction, the paper feed roller  6  is driven to rotate in the housing space  4  in which the cassette  5  containing the papers  2  of size corresponding to a prescription data is mounted. At this time, a friction force is generated between the paper feed roller  6  and the paper  2  urged upward by the spring  9 . The spring force is large in comparison to the weight of the flexible sheet  16  which comes into close contact with the upper most paper  2 . Therefore, the uppermost paper  2  and the flexible sheet  16  commence moving together as the paper feed roller  6  rotates. Thus, in comparison to a case that no flexible sheet is put on, the state of conveying the paper  2  becomes stable. That is, in the case of only paper  2 , there is a possibility that the paper  2  is conveyed on the skew according to a slight difference of condition such as a contact condition between the paper  2  and the paper feed roller  6 . On the other hand, in the case that the flexible sheet is put on, since an influence of the weight of the flexible sheet becomes larger, no bad influence is exerted to the conveyance of the paper  2  even if a condition is slightly different, for example, a contact pressure between the paper  2  and the paper feed roller  6  is different in the width direction. 
   When the rotation of the paper feed roller  6  allows the paper  2  and the flexible sheet  16  to move, the edge of the engagement hole  18  of the attachment piece  17  comes into contact with the guide piece  14 , inhibiting the flexible sheet  16  from moving further. The friction force generated between the paper feed roller  6  and the uppermost paper  2  is larger than the friction force generated between the paper  2  and the flexible sheet  16  which comes into close contact with the paper  2 . Therefore, only the paper  2  keeps moving. Movement of only the uppermost paper  2  allows a part of the flexible sheet  16  to come into close contact with the surface of the next paper  2  as shown in  FIG. 6 . The friction coefficient between the paper  2  and the flexible sheet  17  is lager than the friction coefficient between the papers  2 . Therefore, the next paper  2  is prevented from being moved by the friction force from the flexible sheet  16 , whereby only the paper  2  positioned uppermost can be conveyed as the paper feed roller rotates. 
   Thus, in the embodiment explained above, putting the flexible sheet  16  on the stacked paper  2  enables to neglect a slight difference of condition that has been a problem when conveying the paper  2  by the paper feed roller  6 , resulting in good conveyance of the paper  2 . Therefore, the paper  2  can be conveyed stably on the straight. Even in a case of printing, the printing direction never skews. In addition, after commencement of conveying, the flexible sheet  16  holds the next paper  2 , preventing a disadvantage that the papers  2  are conveyed in a overlapped state. 
   In the embodiment described above, the flexible sheet  16  is explained as an example of the holding member, though the holding member may be a plurality of line-like members or straps or may also a mesh-like member. Also, the holding member may be a sheet-like member with a various kind of shape formed on the surface thereof. Moreover, it is also possible to stick an other member such as sponge on the surface of the holding member to generate a predetermined friction force between such member and the paper  2 . 
   In addition, a coating of conductive material may be applied on the top face of the flexible sheet  16 , or carbon and so on may be impregnated in the surface of the flexible sheet  16 , preventing a bad influence due to a static electricity generated on the paper  2 . In this case, as shown in  FIG. 8 , coatings  16   a  and  16   b  of different conductive material (for example, carbon and aluminum) may be preferably applied on the top and bottom faces of the flexible sheet  16  to use either according to the difference (for example, normal quality paper and propylene) of the paper  2  to be used. 
   As is clear from the above description, according to the present invention, as the flexible sheet is put on the paper in the cassette, it is possible to reliably feed only one paper. 
   Although the present invention has been fully described by way of the examples with reference to the accompanying drawing, it is to be noted that various changes and modifications will be apparent to those skilled in the art. Therefore, unless such changes and modifications otherwise depart from the spirit and scope of the present invention, they should be construed as being included therein.