Patent Publication Number: US-9902172-B2

Title: Printer apparatus

Description:
TECHNICAL FIELD 
     The disclosures herein relate to a printer apparatus. 
     BACKGROUND ART 
     Printers for producing sales receipts or the like are widely used in cash registers used in stores, ATMs (automatic teller machines) or CDs (cash dispensers) installed in banks, etc. In a printer for producing sales receipts or the like, a thermal head or the like prints on thermal paper serving as recording paper while the recording paper is advanced. After the recording paper is advanced a predetermined length, a cutter apparatus cuts a predetermined length of the recording paper from the rest of the paper. 
     Such a cutter apparatus has a fixed blade and a movable blade. The movable blade is moved toward the fixed blade to cut recording paper that is placed between the fixed blade and the movable blade. 
     RELATED-ART DOCUMENTS 
     Patent Document 
     [Patent Document 1] Japanese Patent Application Publication No. 2003-19845 
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     In the above-noted printer apparatus that uses a thermal head or the like to print on recording paper, the recording paper is placed between the thermal head for printing and a platen roller for advancing the recording paper, and printing is performed while the thermal head is pressed against the platen roller. 
     Further miniaturization and cost reduction are required of such a printer apparatus. 
     Means to Solve the Problem 
     According to an aspect of the embodiments, a printer apparatus includes a print head, a platen roller having a rod, a spring configured to press the print head toward a direction of the platen roller, a frame having in a side face thereof a platen supporting groove for supporting the rod of the platen roller, and a detection switch, wherein the platen supporting groove includes a first edge situated toward a direction of the print head and a second edge situated opposite from the first edge, and has on the second edge a projection projecting toward inside the platen supporting groove, and wherein placing the rod of the platen roller at a predetermined position at a deeper side of the platen supporting groove than the projection causes the rod of the platen roller to press the detection switch due to an urging force that is applied to the platen roller by the spring through the print head. 
     Advantage of the Invention 
     According to at least one embodiment, miniaturization and cost reduction are achieved in respect of a printer apparatus using a thermal head or the like. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a drawing illustrating the structure of a printer apparatus. 
         FIG. 2A  is a drawing illustrating the printer apparatus. 
         FIG. 2B  is a drawing illustrating the printer apparatus. 
         FIG. 3A  is a drawing illustrating the printer apparatus. 
         FIG. 3B  is a drawing illustrating the printer apparatus. 
         FIG. 4  is a drawing illustrating the structure of the printer apparatus according to the present embodiment. 
         FIG. 5A  is a drawing illustrating the printer apparatus of the present embodiment. 
         FIG. 5B  is a drawing illustrating the printer apparatus of the present embodiment. 
         FIG. 6  is an axonometric view of a letter-V spring. 
         FIG. 7  is an axonometric view of the printer apparatus according to the present embodiment. 
         FIG. 8  is an axonometric view of the printer apparatus according to the present embodiment. 
         FIG. 9  is a drawing illustrating a platen supporting groove and a mechanical switch. 
         FIG. 10  is an enlarged view of a main part of the printer apparatus according to the present embodiment. 
         FIG. 11  is an axonometric view of the printer apparatus according to the present embodiment. 
         FIG. 12  is a drawing illustrating the printer apparatus of the present embodiment. 
         FIG. 13  is a drawing illustrating the printer apparatus of the present embodiment. 
         FIG. 14  is an enlarged view of a main part of the printer apparatus according to the present embodiment. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     In the following, embodiments for implementing the invention will be described. The same members or the like are referred to by the same numerals, and a description thereof will be omitted 
     A description will be first given of a typical printer apparatus using a thermal head by referring to  FIG. 1  and  FIGS. 2A and 2B . The printer apparatus using a thermal head illustrated in  FIG. 1  includes a thermal head  910  serving as a print head for printing on recording paper and a platen roller  920  for conveying the recording paper. Recording paper (not shown) for printing, which is placed between the thermal head  910  and the platen roller  920 , is advanced by the rotation of the platen roller  920  while the thermal head  910  prints on the recording paper. In such a printer apparatus, a spring  930  presses the thermal head  910  toward the platen roller  920 . The spring  930  which is a head pressuring spring has a letter-V shape. The spring  930  in the installed state in the printer apparatus exerts a restoring force such that the letter-V shape widens. The spring  930 , which is installed between a frame  940  and the thermal head  910 , exerts a restoring force acting in the direction in which the letter-V widens as illustrated by arrows, thereby pressing the thermal head  910  toward the platen roller  920 . 
     In the case of being formed of metal die cast such as aluminum, the frame  940  exhibits high strength, and does not deform even when the spring  930  is placed between the frame  940  and the thermal head  910 . Due to requirements for cost reduction, however, the frame  940  may be formed of resin material. In such a case, the resin material is easy to deform, so that installing the spring  930  between the frame  940  and the thermal head  910  to cause the restoring force of the spring  930  to press the frame  940  made of resin material possibly deforms the frame  940 . The force exerted by the spring  930  to press the thermal head  910  toward the platen roller  920  may thus diminish. Further, the deformation of the frame  940  may possibly destroy the printer apparatus. 
     Such a printer apparatus illustrated has a recording paper guide  950  made of resin material or the like for guiding the recording paper before entry into the space between the thermal head  910  and the platen roller  920 . As illustrated in  FIG. 2A , a projection  911  situated at an end of the thermal head  910  opposite from the side of the thermal head  910  for printing on the recording paper (not shown) is placed between the frame  940  and the recording paper guide  950 . The projection  911  of the thermal head  910  serves as a rotation axis of the thermal head  910  when the spring  930  presses the thermal head  910  toward the platen roller  920 .  FIG. 2B  is a bottom view of the printer apparatus.  FIG. 2A  is a cross-sectional view taken along a dot-and-dash line  2 A- 2 B in  FIG. 2B . 
     As illustrated in  FIG. 3A , a side face  941  of the frame has a platen supporting groove  942  formed therein for supporting the rod  920   a  of the platen roller  920 . For the purpose of allowing other parts of the printer apparatus to be easily seen, only the outline of the side face  941  at the position of the platen supporting groove  942  is shown in a solid line, and the side face  941  of the frame is illustrated as being transparent. In this printer apparatus, a restoring force of a platen-rod holding spring  990  holds the rod  920   a  as illustrated in  FIG. 3B  when the rod  920   a  of the platen roller  920  is placed in the platen supporting groove  942  formed in the side face  941 . This ensures that the rod  920   a  of the platen roller  920  is rotatably placed at a predetermined position in the platen supporting groove  942  formed in the side face  941  of the frame. 
     In  FIG. 3A  and  FIG. 3B , a mechanical switch  980  attached to the side face  941  of the frame has a press part  981 . Whether the rod  920   a  of the platen roller  920  is set in the platen supporting groove  942  can be detected based on the on or off state of the mechanical switch  980 . Pressing down the press part  981  of the mechanical switch  980  causes the mechanical switch to be in the on (or off) state, thereby allowing the detection of the event that the rod  920   a  of the platen roller  920  is set in the predetermined position. In this manner, the printer apparatus illustrated in  FIG. 3A  and  FIG. 3B  has the press part  981  of the mechanical switch  980  that is pressed by the rod  920   a  of the platen roller  920  that is pressed by the platen-rod holding spring  990 . 
     In the following, the printer apparatus of the present embodiment will be described with reference to  FIG. 4  and  FIGS. 5A and 5B . The printer apparatus of the present embodiment includes a thermal head  10  serving as a print head for printing on recording paper and a platen roller  20  for conveying the recording paper. Recording paper (not shown) for printing, which is placed between the thermal head  10  and the platen roller  20 , is advanced by the rotation of the platen roller  20  while the thermal head  10  prints on the recording paper. In the present embodiment, the term “thermal head  10 ” may sometimes refer to the entire structure inclusive of a thermal head as well as a heat sink and the like attached to the thermal head. 
     The printer apparatus of the present embodiment has a letter-V spring  30  for pressing the thermal head  10  toward the platen roller  20 . The letter-V spring  30 , when installed in the printer apparatus as illustrated in  FIG. 4 , exerts a restoring force in the direction indicated by arrows in  FIG. 4 . Specifically, the restoring force acts in such a direction as to narrow the letter-V shape in the state illustrated in  FIG. 4 . Namely, the letter-V spring  30  is installed such that the restoring force serves to bring the first part  31  and the second part  32  of the letter-V spring  30  closer to each other. In the present embodiment, the first part  31  of the letter-V spring  30  is secured in contact with the recording paper guide  50  made of resin material, and a head contact  33  of the second part  32  is in contact with the back face of the thermal head  10 , thereby pressing the thermal head  10  toward the side where the platen roller  20  is situated. The head contact  33  is formed by bending the end of the second part  32  of the letter-V spring  30  into an arc shape. 
     The printer apparatus of the present embodiment utilizes such a letter-V spring  30 , so that even in the case of the frame being made of resin material, the frame does not deform because the restoring force of the letter-V spring  30  is not applied to the wall of the frame extending in the width direction. It is thus safe to make the frame by use of resin material. Further, there is no need to provide a frame for supporting the letter-V spring  30 , which enables the size reduction of the printer apparatus as well as cost reduction. As illustrated in  FIGS. 5A and 5B , a projection  11  formed at an end of the thermal head  10  opposite from the side of the thermal head  10  for printing on printing paper (not shown) is inserted into a groove  34  formed in the first part  31  of the letter-V spring  30 . The projection  11  is wedged between the first part  31  of the letter-V spring  30  and the recording paper guide  50  made of resin material. The projection  11  of the thermal head  10  serves as a rotation axis of the thermal head when the letter-V spring  30  presses the thermal head  10  toward the platen roller  20 .  FIG. 4B  is a bottom view.  FIG. 5A  is a cross-sectional view taken along a dot-and-dash line  5 A- 5 B in  FIG. 5B . It may be noted that  FIG. 5A  shows a cross-sectional view taken at a different cross-sectional position than in  FIG. 4 . 
     In the following, the letter-V spring  30  will be described in more detail with reference to  FIG. 6 . The letter-V spring  30  is of a leaf-spring type, and may be referred to as a V spring. The letter-V spring  30  has the first part  31  and the second part  32 , which are parts of a single seamless, continuous metal plate. The portion of the metal plate that serves as the second part  32  is bent relative to the portion of the metal plate serving as the first part  31 . More than one second part  32  may be formed in order to apply uniform pressure to the thermal head  10 . The end of the second part  32  has the head contact  33  that comes in contact with the thermal head  10  for the purpose of applying a force to the thermal head  10 . The first part  31  has a wide flat shape for serving as part of a frame, a center part of which has the groove  34  into which the projection  11  of the thermal head  10  can be inserted. The projection  11  of the thermal head  10  is wedged between the letter-V spring  30  and the recording paper guide  50  in the groove  34  of the first part  31  of the letter-V spring  30  such as to be rotatable. With this arrangement, the thermal head  10  is able to rotate around the projection  11  serving as a rotation axis. 
     The letter-V spring  30  is made of metal material such as stainless, and thus has the function to release heat generated by a conveyance motor  60  or the like, which will be described later. The letter-V spring  30  can also serve as part of the ground due to its high electrical conductivity. Further, the letter-V spring  30  has high strength, so that the first part  31  of the letter-V spring  30  may also constitute part of the housing of the printer apparatus. 
       FIG. 7  and  FIG. 8  are axonometric views of the printer apparatus of the present embodiment. The printer apparatus of the present embodiment includes the conveyance motor  60  for rotating the platen roller  20  and a gear box  61  for transmitting the rotation of the conveyance motor  60  to the platen roller  20 . The recording paper guide  50  has an opening formed therein, at the position of which a recording paper sensor  70  is installed. The frame  40  of the printer apparatus has a frame side face  41 . 
     In the printer apparatus of the present embodiment, as illustrated in  FIG. 9 , the frame side face  41  of the frame  40  has a platen supporting groove  42  formed therein for supporting the rod  20   a  of the platen roller  20 . The platen supporting groove  42  has a supporting-groove projection  43  formed on the edge thereof opposite from an edge  42   a  situated on the same side as the thermal head  10 , such that the supporting-groove projection  43  projects towards inside the platen supporting groove  42 . A first slope  44  is formed at a deeper depth into the platen supporting groove  42  than the supporting-groove projection  43  (i.e., below the supporting-groove projection  43  as illustrated in  FIG. 9 ). A second slope  45  is formed further toward the entrance to the platen supporting groove  42  than the supporting-groove projection  43  (i.e., above the supporting-groove projection  43  as illustrated in  FIG. 9 ). Further, the frame side face  41  has a mechanical switch  80  attached thereto that serves as a position detection switch to detect the rod  20   a  of the platen roller  20 . Pressing a press part  81  of the mechanical switch  80  causes the press part  81  to be pressed down, thereby placing the mechanical switch  80  in the on or off state.  FIG. 10  is an enlarged view of a portion of the platen supporting groove  42  where the supporting-groove projection  43 , the first slope  44 , and the second slope  45  are formed. 
     In the printer apparatus of the present embodiment, the event that the rod  20   a  of the platen roller  20  is installed at the predetermined position in the platen supporting groove  42  (see  FIG. 9 ) as illustrated in  FIG. 11  causes the rod  20   a  of the platen roller  20  to press and turn on or off the press part  81  of the mechanical switch  80 . This allows the detection of the event that the rod  20   a  of the platen roller  20  is installed at the predetermined position in the platen supporting groove  42 . Namely, the on or off state of the mechanical switch  80  enables the detection of whether the rod  20   a  of the platen roller  20  is installed at the predetermined position in the platen supporting groove  42 . 
     In the present embodiment, the letter-V spring  30  presses the thermal head  10  toward the direction of the platen roller  20 . Namely, the restoring force of the letter-V spring  30  presses the platen roller  20  through the thermal head  10 . In the state that is to be considered first, the rod  20   a  of the platen roller  20  is situated in the platen supporting groove  42  further toward the entrance to the platen supporting groove  42  than the supporting-groove projection  43  as illustrated in  FIG. 12 . In this case, the restoring force of the letter-V spring  30  acting in the direction indicated by an arrow  12 A in  FIG. 12  presses, and thus moves, the rod  20   a  of the platen roller  20  along the second slope  45  in the direction indicated by an arrow  12 B in  FIG. 12 , so that the rod  20   a  of the platen roller  20  exits from the platen supporting groove  42 . 
     In the state that is to be considered next, the rod  20   a  of the platen roller  20  is situated at a deeper depth into the platen supporting groove  42  than the supporting-groove projection  43  of the platen supporting groove  42  as illustrated in  FIG. 13 . In this case, the restoring force of the letter-V spring  30  acting in the direction indicated by an arrow  13 A in  FIG. 13  presses, and thus moves, the rod  20   a  of the platen roller  20  along the first slope  44  in the direction indicated by an arrow  13 B in  FIG. 13 , so that the rod  20   a  of the platen roller  20  is pressed into the predetermined position in the platen supporting groove  42 . This allows the rod  20   a  of the platen roller  20  to be installed at the predetermined position in the platen supporting groove  42 . It may be noted that  FIG. 14  is an enlarged view of the rod  20   a  and the surrounding area when the rod  20   a  of the platen roller  20  is installed at the predetermined position in the platen supporting groove  42  as in  FIG. 13 . In the present embodiment, the shape of the first slope  44  is configured to conform to the curvature of the rod  20   a  of the platen roller  20 . 
     In the manner described above, the letter-V spring  30  applies a restoring force to the platen roller  20  even in the state in which the rod  20   a  of the platen roller  20  is resting in position in the platen supporting groove  42 , which thus keeps the rod  20   a  of the platen roller  20  secured in the platen supporting groove  42 . In such a state, the restoring force of the letter-V spring  30  causes the rod  20   a  of the platen roller  20  to press and turn on or off the press part  81  of the mechanical switch  80 , thereby enabling the detection of the fact that the rod  20   a  of the platen roller  20  is installed at the predetermined position in the platen supporting groove  42 . The force by which the rod  20   a  of the platen roller  20  presses the press part  81  of the mechanical switch  80  is attributable to the restoring force of the letter-V spring  30 . 
     In this manner, the present embodiment allows the number of springs to be reduced to one unlike the printer apparatus that needs two types of springs, i.e., the spring  930  (see  FIG. 1 ) for pressing the thermal head  910  toward the platen roller  920  and the platen-rod holding spring  990  (see  FIG. 3B ) for holding the rod  920   a  of the platen roller  920  in the platen supporting groove  942 . With this arrangement, the printer apparatus of the present embodiment enables the reduction of the number of components, thereby lowering the cost of the printer apparatus. 
     Further, although a description has been given with respect to one or more embodiments of the present invention, the contents of such a description do not limit the scope of the invention. 
     The present application claims foreign priority to Japanese priority application No. 2014-113251 filed on May 30, 2014 with the Japanese Patent Office, the entire contents of which are hereby incorporated by reference. 
     DESCRIPTION OF REFERENCE SYMBOLS 
       10  thermal head 
       11  rotational projection 
       20  platen roller 
       20   a  rod 
       30  letter-V spring 
       31  first part 
       32  second part 
       33  head contact 
       34  groove 
       40  frame 
       41  frame side face 
       42  platen supporting groove 
       43  supporting-groove projection 
       44  first slope 
       45  second slope 
       50  recording paper guide 
       60  conveyance motor 
       61  gear box 
       70  recording paper sensor 
       80  mechanical switch 
       81  press part