Patent Publication Number: US-7712736-B2

Title: Printer apparatus with cam dampened tray

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a printer apparatus, and more particularly to a printer apparatus achieving suppression of noise. 
   2. Description of the Background Art 
   A printer apparatus including a paper feed mechanism for feeding paper one by one by means of a paper feed roller and a friction pad has been available. Here, a printer apparatus proposed in Japanese Patent Laying-Open No. 2003-221132 will be described by way of example. In the printer apparatus of this type, as shown in  FIG. 10 , a paper feed roller  106  and a friction pad  105  are disposed above a paper carrier plate  102  for carrying the paper. Paper feed roller  106  is attached to a prescribed shaft portion  104 . 
   A spring  108  for pushing paper carrier plate  102  upward is disposed below paper carrier plate  102 . In order to lift paper carrier plate  102  by making use of pushing force of spring  108  concurrently with rotation of paper feed roller  106 , a cam  110  is attached to shaft portion  104 , and a cam abutment portion  112  abutting on cam  110  is provided in paper carrier plate  102 . 
   In this printer apparatus, cam  110  shown in  FIG. 10  is initially in abutment on cam abutment portion  112 . Then, as shown in  FIG. 11 , cam  110  rotates in a direction shown with an arrow  131 , and a state where cam  110  abuts on cam abutment portion  112  is released. Then, paper carrier plate  102  is lifted and paper  103  is fed by paper feed roller  106  and friction pad  105 . Here, in order to mitigate impact due to sudden lifting of paper carrier plate  102  as well as to suppress noise, an elastic member  113  such as a leaf spring is attached to shaft portion  104  in a manner adjacent to cam  110 . The paper feed mechanism in a conventional printer apparatus has thus been structured. 
   On the other hand, the conventional printer apparatus suffers from the following disadvantages. As described above, in order to mitigate impact due to sudden lifting of paper carrier plate  102  as well as to suppress noise, an additional member such as a leaf spring serving as elastic member  113  has been necessary. Moreover, such an additional elastic member  113  should be attached to shaft portion  104  in a manner adjacent to cam  110 . Accordingly, the number of parts as well as the number of assembly steps have increased, which has turned out as obstacles in reducing manufacturing cost. 
   SUMMARY OF THE INVENTION 
   The present invention was made to solve the above-described problems. An object of the present invention is to provide a printer apparatus achieving suppression of noise by mitigating impact made by a paper carrier plate without increasing manufacturing cost. 
   A printer apparatus according to the present invention includes a paper carrier plate portion, a prescribed shaft portion, a paper feed roller, a pushing member, a cam, and a cam abutment portion. The paper carrier plate portion carries paper on which an image is printed. The prescribed shaft portion is arranged above the paper carrier plate portion. The paper feed roller for feeding the paper is provided on the shaft portion. The pushing member pushes the paper carrier plate portion toward the paper feed roller. The cam is provided on the shaft portion. The cam abutment portion is provided in the paper carrier plate portion and abuts on the cam. The cam is formed from a resin and includes a cut-out portion so that a portion of the cam abutting on the cam abutment portion when the paper carrier plate portion is lifted is elastic. It is noted that the cut-out portion used herein refers to a portion formed by hollowing out a member in a manner penetrating from one end to the other end. 
   According to this structure, the cut-out portion is provided in the portion of the cam abutting on the cam abutment portion when the paper carrier plate portion is lifted in order to feed the paper. Therefore, in the cam formed from the resin, the cut-out portion and a peripheral portion of the cam surrounding the cut-out portion from an outer circumference and having a smaller thickness in a radial direction attain a function as buffer members. As a result, the cam itself can mitigate the impact caused when the cam abutment portion again abuts on the cam, and serve to suppress noise in the printer apparatus, without using an additional member such as a leaf spring. 
   Another printer apparatus according to the present invention includes a paper carrier plate portion, a pushing member, and a cam. The paper carrier plate portion carries paper on which an image is printed. The pushing member pushes the paper carrier plate portion upward. The cam abuts on the paper carrier plate portion, and permits lifting of the paper carrier plate portion as a result of pushing force of the pushing member in feeding the paper. At least one of the cam and a portion abutting on the cam in the paper carrier plate portion is provided with an elastic portion in an area where the cam and the portion abut on each other when the paper carrier plate portion is lifted. 
   According to this structure, at least one of the cam and the portion abutting on the cam in the paper carrier plate portion includes the elastic portion in the area where they abut on each other when the paper carrier plate portion is lifted for feeding the paper. Therefore, the cam itself or the paper carrier plate portion itself can mitigate the impact caused when the cam abutment portion again abuts on the cam, and serve to suppress noise in the printer apparatus, without using an additional member such as a leaf spring. 
   According to one manner of such an elastic portion, the cam is formed from a resin and has a cut-out portion, and the elastic portion includes the cut-out portion and a peripheral portion of the cam circumferentially surrounding the cut-out portion. 
   In addition, when the elastic portion is formed in the cam, the peripheral portion of the cam may be continuously formed such that the cut-out portion is closed in a circumferential direction. Alternatively, the peripheral portion of the cam may have a discontinuous portion formed on one side in the circumferential direction so as to avoid enclosure of the cut-out portion in the circumferential direction. Alternatively, the elastic portion may include an elastic member provided around an outer circumference of the cam. 
   According to another manner of the elastic portion, the portion abutting on the cam in the paper carrier plate portion may be formed from a resin and have a cut-out portion, and the elastic portion may include a portion of the cam abutment portion circumferentially surrounding the cut-out portion. 
   In this case as well, the paper carrier plate portion itself can mitigate the impact caused when the cam abutment portion again abuts on the cam, and serve to suppress noise in the printer apparatus, without using an additional member such as a leaf spring. 
   The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view showing a paper feed mechanism in a printer apparatus according to an embodiment of the present invention. 
       FIG. 2  is a side view of a manner of paper feed in the embodiment. 
       FIG. 3  is a side view of one state illustrating an operation for paper feed in the printer apparatus in the embodiment. 
       FIG. 4  is a side view of a state subsequent to the state shown in  FIG. 3  in the embodiment. 
       FIG. 5  is a side view of a state subsequent to the state shown in  FIG. 4  in the embodiment. 
       FIG. 6  is a side view showing one example of a cam applied to the printer apparatus in the embodiment. 
       FIG. 7  is a side view showing another example of a cam applied to the printer apparatus in the embodiment. 
       FIG. 8  is a side view showing yet another example of a cam applied to the printer apparatus in the embodiment. 
       FIG. 9  is a side view showing one example of a cam abutment portion applied to the printer apparatus in the embodiment. 
       FIG. 10  is a perspective view showing a paper feed mechanism in a conventional printer apparatus. 
       FIG. 11  is a side view showing a manner of paper feed in the conventional printer apparatus. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A paper feed mechanism in a printer apparatus according to the embodiment of the present invention will now be described. As shown in  FIG. 1 , a paper carrier plate  2  for carrying the paper on which an image is printed is disposed in the printer apparatus. A paper feed roller  6  and a friction pad  5  are disposed above paper carrier plate  2 . Paper feed roller  6  is attached to a prescribed shaft portion  4 . In order to reliably catch and feed the paper, for example, rubber  6   a  is formed around paper feed roller  6 . 
   A spring  8  for pushing paper carrier plate  2  upward is disposed below paper carrier plate  2 . In order to lift paper carrier plate  2  by making use of pushing (elastic) force of spring  8  concurrently with rotation of paper feed roller  6 , a cam  10  including a stepped portion  10   b  is attached to shaft portion  4 . Meanwhile, a cam abutment portion  12  abutting on cam  10  is provided in paper carrier plate  2 . Cam  10  is formed, for example, from a resin. 
   As will be described later, in order to mitigate impact caused when paper carrier plate  2  is lifted as a result of rotation of cam  10  and release from an abutting state of cam  10  on cam abutment portion  12 , a prescribed cut-out portion  10   a  is provided. As shown in  FIG. 2 , while paper carrier plate  2  is lifted, paper  3  is fed by paper feed roller  6  and friction pad  5 . 
   An operation of the paper feed mechanism of the printer apparatus described above will now be discussed. Initially, when a paper feed operation is started by exiting from a stand-by state, as shown in  FIG. 3 , cam  10  starts to rotate together with shaft portion  4  in a direction shown with an arrow  31 . As cam  10  continues to rotate, stepped portion  10   b  of cam  10  abuts on cam abutment portion  12  as shown in  FIG. 4 . 
   When cam  10  further rotates, cam abutment portion  12  is released from such a state as pressed from above by stepped portion  10   b . Thereafter, cam abutment portion  12  is lifted by the elastic force of spring  8 , and again abuts on cam  10 . Here, cam abutment portion  12  abuts on a peripheral portion  10   c  around cut-out portion  10   a  of cam  10 . 
   While paper carrier plate  2  is lifted, the paper carried on paper carrier plate  2  is fed by paper feed roller  6  as shown in  FIG. 2 . By repeating the operation described above, the paper carried on paper carrier plate  2  is fed one by one. 
   In the paper feed mechanism of the printer apparatus described above, after cam abutment portion  12  is released from such a state as pressed from above by stepped portion  10   b  of cam  10 , paper carrier plate  2  is lifted by the elastic force of spring  8 , whereby a paper feed operation is performed. Cam  10  is provided with cut-out portion  10   a  in an area where cam abutment portion  12  again abuts on cam  10  when paper carrier plate  2  is lifted, as shown in  FIGS. 5 and 6 . 
   Accordingly, in cam  10  formed from the resin, cut-out portion  10   a  and peripheral portion  10   c  of the cam surrounding cut-out portion  10   a  from the outer circumference and having a smaller thickness in a radial direction attain a function as buffer members. Therefore, cam  10  itself can mitigate the impact caused when cam abutment portion  12  again abuts on cam  10 , and serve to suppress noise in the printer apparatus, without using an additional member such as a leaf spring. 
   In addition to the cam as shown in  FIG. 6  provided with the peripheral portion such that the cut-out portion is closed in a circumferential direction, a cam as shown in  FIG. 7  may be employed, which is provided with a discontinuous portion  10   d  between stepped portion  10   b  and peripheral portion  10   c  of the cam that surrounds cut-out portion  10   a  from the outer circumference so as not to close cut-out portion  10   a  in the circumferential direction. As a result of provision of discontinuous portion  10   d , peripheral portion  10   c  of the cam is supported solely by one side of a cam body. Therefore, the impact can more effectively be mitigated. Moreover, as shown in  FIG. 8 , cam  10  having an elastic member  10   e  such as rubber attached to a part of the surface of cam  10  abutting on cam abutment portion  12  may be employed. 
   Alternatively, instead of providing the cut-out portion in the cam, a cut-out portion  12   a  may be provided in cam abutment portion  12 , as shown in  FIG. 9 . In this case as well, cam abutment portion  12  having cut-out portion  12   a  attains a function as the buffer member, and cam abutment portion  12  itself can mitigate the impact caused when cam abutment portion  12  again abuts on cam  10 , and serve to suppress noise in the printer apparatus, without using an additional member such as a leaf spring. 
   Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.