Abstract:
A printing apparatus configured to carry out printing on paper with a printing head, while holding the paper between the printing head and a platen roller, includes: a paper guide block guiding the paper in between the printing head and the platen roller, and holding the platen roller; and a force applying member applying a force to any one of the paper guide block and the printing head in such a manner as to press the any one of the paper guide block and the printing head.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a printing apparatus, and, in particular, to a printing apparatus in which paper is inserted between a printing head and a platen roller and printing to the paper is carried out.  
         [0003]     2. Description of the Related Art  
         [0004]     A printing apparatus is incorporated in a portable terminal unit such as a POS terminal, a ticket terminal or such, for carrying out printing for a print such as a receipt, a ticket or such (see Japanese Laid-open Patent Application No. 2000-94767).  
         [0005]     In the printing apparatus, paper is held between a printing head and a platen roller, and printing is carried out with the printing head to the paper.  
         [0006]     At this time, in order to hold the paper between the printing head and the platen roller, the printing head and the platen roller are pressed together with a coil spring or such provided on a surface perpendicular to the printing head and the platen roller. Further, a paper guide is provided for guiding the paper to between the printing head and the platen roller.  
       SUMMARY OF THE INVENTION  
       [0007]     In the printing apparatus in the prior art, since the printing head and the platen roller are pressed together with a coil spring or such provided on a surface perpendicular to the printing head and the platen roller as mentioned above, an extra space is required in a direction in which the printing head and the platen roller are supported, and thus, reduction in the apparatus thickness may become difficult. Further, the number of components increases, and a structure may become complicate accordingly. Therefore, a printing apparatus having a construction such that the structure can be simplified, and also, miniaturization is possible, is required.  
         [0008]     The present invention has been devised in consideration of these points, and an object of the present invention is to provide a printing apparatus for which a structure can be simplified, and also, miniaturization is possible.  
         [0009]     According to the present invention, in a printing apparatus configured to carry out printing on paper with a printing head while holding the paper between the printing head and a platen roller, a paper guide block guiding the paper in between the printing head and the platen roller and holding the platen roller; and a force applying member applying a force to any one of the paper guide block and the printing head in such a manner as to press any one of the paper guide block and the printing head, are provided.  
         [0010]     In this configuration, the force applying member applies a force to the paper guide block which guides the paper to between the printing head and the platen roller and also holds the platen roller and the paper or to the printing head so that the paper guide block or the printing head is pressed to one another, and thus, a part which rotatably supports the platen roller and the printing head can be integrally provided. As a result, it is possible to reduce the number of components, and thus, it is possible to simplify the structure and achieve miniaturization.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     Other objects and further features of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings:  
         [0012]      FIG. 1  shows a perspective view of a first embodiment of the present invention;  
         [0013]      FIG. 2  shows a perspective view of a frame  111 ;  
         [0014]      FIG. 3  shows a perspective view of a printing head  112 ;  
         [0015]      FIG. 4  shows a perspective view of a paper guide block  113 ;  
         [0016]      FIGS. 5 and 6  illustrate operation of the first embodiment of the present invention;  
         [0017]      FIG. 7  shows a perspective view of a second embodiment of the present invention;  
         [0018]      FIG. 8  shows a perspective view of a frame  211 ;  
         [0019]      FIG. 9  shows a perspective view of a printing head  212 ;  
         [0020]      FIG. 10  shows a perspective view of a paper guide block  213 ;  
         [0021]      FIG. 11  shows a perspective view of a ground rod spring  214 ;  
         [0022]      FIG. 12  illustrates operation of the second embodiment of the present invention;  
         [0023]      FIG. 13  shows a perspective view of a third embodiment of the present invention;  
         [0024]      FIG. 14  shows a perspective view of a frame  311 ;  
         [0025]      FIG. 15  shows a perspective view of a paper guide block  313 ;  
         [0026]      FIG. 16  shows a perspective view of a U-spring  314 ;  
         [0027]      FIG. 17  shows a perspedctive view of a relevant part in a state in which the U-spring  314  is mounted in the paper guide block  313 ;  
         [0028]      FIG. 18  illustrates operation of the third embodiment of the present invention;  
         [0029]      FIG. 19  shows a perspective view of a fourth embodiment of the present invention;  
         [0030]      FIG. 20  shows a perspective view of a paper guide block  413 ;  
         [0031]      FIG. 21  shows a perspective view of a paper guide block  413  at a time of assembling;  
         [0032]      FIG. 22  shows a perspective view of a fifth embodiment of the present invention;  
         [0033]      FIG. 23  shows a perspective view of a frame  511 :  
         [0034]      FIG. 24  shows a perspective view of a paper guide block  513 ;  
         [0035]      FIG. 25  illustrates operation of the fifth embodiment of the present invention;  
         [0036]      FIG. 26  shows a perspective view of a sixth embodiment of the present invention;  
         [0037]      FIG. 27  shows a perspective view of a paper guide block  613 ;  
         [0038]      FIG. 28  shows a perspective view of a rod spring  614 ;  
         [0039]      FIG. 29  illustrates operation of the sixth embodiment of the present invention;  
         [0040]      FIG. 30  shows a front perspective view of a seventh embodiment of the present invention;  
         [0041]      FIG. 31  shows a rear perspective view of the seventh embodiment of the present invention;  
         [0042]      FIG. 32  shows a bottom perspective view of the seventh embodiment of the present invention;  
         [0043]      FIG. 33  shows a plan view of the seventh embodiment of the present invention;  
         [0044]      FIG. 34  shows a sectional view of a relevant part of the seventh embodiment of the present invention;  
         [0045]      FIG. 35  shows a front perspective view of a base frame  711 ;  
         [0046]      FIG. 36  shows a rear perspective view of the base frame  711 ;  
         [0047]      FIG. 37  shows a bottom perspective view of the base frame  711 ;  
         [0048]      FIG. 38  shows a front perspective view of a paper guide block  717 ;  
         [0049]      FIG. 39  shows a rear perspective view of the paper guide block  717 ;  
         [0050]      FIG. 40  shows a bottom perspective view of the paper guide block  717 ;  
         [0051]      FIG. 41  shows a sectional view of a relevant part of the seventh embodiment of the present invention;  
         [0052]      FIG. 42  shows a front perspective view of a first variant embodiment of the seventh embodiment of the present invention;  
         [0053]      FIG. 43  shows a rear perspective view of the first variant embodiment of the seventh embodiment of the present invention;  
         [0054]      FIG. 44  shows a bottom perspective view of the first variant embodiment of the seventh embodiment of the present invention;  
         [0055]      FIG. 45  shows a plan view of the first variant embodiment of the seventh embodiment of the present invention;  
         [0056]      FIG. 46  shows a sectional view of the first variant embodiment of the seventh embodiment of the present invention;  
         [0057]      FIG. 47  shows a sectional perspective view of a relevant part of the first variant embodiment of the seventh embodiment of the present invention;  
         [0058]      FIG. 48  shows a front perspective view of a paper guide block  811 ;  
         [0059]      FIG. 49  shows a rear perspective view of the paper guide block  811 ;  
         [0060]      FIG. 50  shows a bottom perspective view of the paper guide block  811 ;  
         [0061]      FIG. 51  shows a perspective view of a second variant embodiment of the seventh embodiment of the present invention; and  
         [0062]      FIG. 52  shows a sectional view of a relevant part of the second variant embodiment of the seventh embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0063]      FIG. 1  shows a perspective view of a first embodiment of the present invention.  
         [0064]     A printing apparatus  100  in the first embodiment includes a frame  111 , a printing head  112 , a paper guide block  113 , a platen roller  114 , coil springs  115 , a motor  116 , a reduction gear mechanism  117 , a gear cover  118 , a flexible printed wiring cable  119  and a sensor  120 .  
         [0000]     [Frame] 
         [0065]      FIG. 2  shows a perspective view of the frame  111 .  
         [0066]     The frame  111  is made of an electrically conducive member such as metal, and includes a base part  121 , a head holding part  122 , a driving mechanism holding part  123  and paper guide block holding parts  124 , which are integrally formed.  
         [0067]     The base part  121  faces a bottom surface of the paper guide block  113 , and has coil spring holding parts  121   a  provided for holding the coil springs  115  on a surface facing the bottom surface of the paper guide block  113 , i.e., the surface in an arrow Z 1  direction side. Further, an optical sensor  120  is mounted on the base part  121 .  
         [0068]     The head holding part  122  has a printing head  112  disposed on a front surface side, i.e., the side of an arrow Y 1 , and, on a rear surface side, i.e., the side of an arrow Y 2  of the head holding part  122 , the flexible printed wiring cable  119  is disposed, which provides data to the printing head  112 , and also, supplies power thereto. The printing head  112  and the flexible printed wiring cable are connected via a through hole  122   a  formed in the head holding part  112 .  
         [0069]     The driving mechanism holding part  123  has the motor  116  disposed on an arrow X 2  side. An output shaft of the motor  116  extends to an arrow X 1  side of the driving mechanism holding part  123  via a through hole  123   a.  A gear is connected to the output shaft. On the arrow X 1  side of the driving mechanism holding part  123 , a shaft  123   b  is formed for holding the reduction gear mechanism  117 . The reduction gear mechanism  117  is loaded to the shaft  123   b,  and transmits a rotation of the output shaft of the motor  116  to the platen roller  114 .  
         [0070]     The paper guide block holding parts  124  are provided on both sides, i.e., the arrows X 1 , X 2  directions of the base part  121 . The paper guide block holding part  124  has projection parts  124   a  projecting in the arrow X 2  direction. The projection parts  124   a  hold the paper guide block  113  rotatably.  
         [0000]     [Printing Head  112 ] 
         [0071]      FIG. 3  shows a perspective view of the printing head  112 .  
         [0072]     The printing head  112  includes a circuit substrate  112   a  on which a thermal head and a driving IC are mounted, a radiator plate  112   b  radiating unnecessary heat and a connector  112   c.  The connector  112   c  has a connector for the flexible printed wiring cable  119  connected thereto. The circuit substrate  112   a  receives power supply from the flexible printed wiring cable  119  via the connector  112   c,  drives the driving IC, heats the thermal head, and carries out printing on heat sensitive paper held between the thermal head and the platen roller  114 .  
         [0000]     [Paper Guide Block  113 ] 
         [0073]      FIG. 4  shows a perspective view of the paper guide block  113 .  
         [0074]     The paper guide block  113  has a configuration such that a paper guide part  131 , bearing parts  132  and holding parts  133  are integrally molded of resin or such.  
         [0075]     The paper guide part  131  extends in the arrows X 1 , X 2  directions, inclines in the arrow Z 1  direction along the arrow Y 2  direction, curls the heat sensitive paper inserted from the arrow Y 1  direction in the arrow Z 1  direction, and guides the heat sensitive paper in between the printing head  112  and the platen roller  114 . In the paper guide part  131 , a through hole  131   a  passing through in the arrow Z 1 , Z 2  directions is formed. The through hole  131   a  is formed at a position facing the sensor  120  mounted on the base part  121  of the frame  111 .  
         [0076]     The bearing parts  132  include bearings  132   a,  cut out parts  132   b,  introduction parts  132   c  and slit parts  132   d.  The bearing parts  132   a  hold a shaft of the platen roller  114  rotatably. The cut out parts  132   b  allows the arrow Z 1  direction end parts of the bearing parts  132   a  to communicate with the outside.  
         [0077]     The introduction parts  132   c  are formed on the arrow Z 1  side in a taper manner such that each gap d reduces in width along the arrow Z 2  direction. By pressing the shaft of the platen roller  114  to the introduction parts  132   b  in the arrow Z 2  direction, the introduction parts  132   b  widen gradually in the arrow Y 1 , Y 2  directions, and the cut out parts open in the arrow Y 1 , Y 2  directions accordingly. Thereby, the shaft of the platen roller  114  can be easily loaded in the bearings  132   a.    
         [0078]     The slit parts  132   d  are formed on both sides of the bearings  132   a,  i.e., the arrow Y 1  direction side and the arrow Y 2  direction side. The slit parts  132   d  are provided for the purpose that, when the shaft of the platen roller  114  is inserted into the bearings  132   a,  the bearings  132   a  are deformed in such a manner that the cut out parts  132   b  open in the arrow Y 1 , Y 2  directions.  
         [0079]     Holding parts  133  are provided at positions on the arrow Z 2  direction side of the arrow Y 2  direction side of the bearings  132 , and project in the arrow Y 2  direction. In the holding parts  133 , through holes  133   a  are formed which rotatably engage with the projection parts  124   a  formed on the paper guide block holding parts  124  of the frame  111 . The paper guide block  113  is mounted on the paper guide block holding part  124  of the frame  111  rotatably about the holding parts  133 .  
         [0000]     [Platen Roller  114 ] 
         [0080]     As shown in  FIG. 1 , the platen roller  114  includes a rotating shaft  114   a,  a roller  114   b  and a gear  114   c.  The rotating shaft  114  is made of a metal rod or such. The roller  114   b  is made of a resin material disposed cylindrically about the rotating shaft  114   a,  presses heat sensitive paper in the direction of the printing head  112 , feeds the heat sensitive paper in the arrow Z 1  direction, and also, causes the heat sensitive paper to contact the printing head  112 .  
         [0081]     The gear  114   c  is fixed to the rotating shaft  114   a.  Further, the gear  114   c  engages with the reduction gear mechanism  117 , and the rotating shaft  114   a  is rotated in an arrow φ 1  direction by means of a rotating driving force transmitted by the reduction gear mechanism  117 . The platen roller  114  rotates according to the rotation of the reduction gear mechanism  117 , and rotates the roller  114   b  in the arrow φ 1  direction. Thus, the heat sensitive paper is fed in the arrow Z 1  direction.  
         [0000]     [Coil Spring] 
         [0082]     The coil springs  115  are held by the coil spring holding parts  121   a  provided on the base part  121  of the frame  111 .  
         [0000]     [Motor  116 ] 
         [0083]     The motor  116  is made of, for example, a stepping motor, and is mounted in the driving mechanism holding part  123  of the frame  111 . The motor  116  generates rotating force and transmits it to the reduction gear mechanism  117 .  
         [0000]     [Reduction Gear Mechanism  117 ] 
         [0084]     The reduction gear mechanism  117  includes a plurality of gears. The plurality of gears are rotatably supported by shafts in such a manner that they together engage with the shaft  123   b  of the driving mechanism holding part  123  of the frame  111 .  
         [0000]     [Gear Cover  118 ] 
         [0085]     A gear cover  118  is loaded on the frame  111 , and covers the motor  116  and the reduction gear mechanism  117 .  
         [0000]     [Flexible Printed Wiring Cable  119 ] 
         [0086]     One end of the flexible printed wiring cable  119  is connected to a controller, not shown, the other end is connected to the printing head  112 , the motor  116  and the sensor  120 , supplies power to the printing head  112 , the motor  116  and the sensor  120  and also, transmits a signal to the controller.  
         [0000]     [Sensor] 
         [0087]     The sensor  120  is made of a reflective type photo-interrupter, and is mounted on the base part  121  of the frame  111 . The sensor  120  is connected to the flexible printed wiring cable  119 , and is driven thereby. Light emitted by the sensor  120  exits through the through hole  131   a  of the paper block guide  113 .  
         [0088]     An output signal of the sensor  120  has a high level when the paper is located on the through hole  131   a  in a state in which the paper guide block  113  is rotated in an arrow θ 2  direction, since the paper is in the proximity to the sensor  120 . Further, the output signal of the sensor  120  has a low level when the paper is not located on the through hole  131   a  in a state in which the paper guide block  113  is rotated in the arrow θ 2  direction, since the light emitted by the sensor  120  exits through the though hole  131   a.  Further, in a state in which the paper guide block  113  is rotated in an arrow θ 1  direction, the light emitted by the sensor  120  exits through the through hole  131   a,  and thus, the output signal of the sensor has the low level. Further, when the paper is located on the through hole  131   a  in a state in which the paper guide block  113  is rotated in an arrow θ 1  direction, the light emitted by the sensor  120  is reflected by the paper and returns. However, in this case, since the distance from the paper is long, the output signal of the sensor  120  has an intermediate level. Thus, by detecting the output signal level and the intermediate level of the sensor  120  by means of a signal processing circuit not shown, it is possible to detect, not only existence/absence of the paper but also existence/absence of the platen roller  114 .  
         [0089]     Thus, by means of the sensor  120 , it is possible to detect existence/absence of the paper and existence/absence of the platen roller  114 . It is noted that, the sensor  120  is not limited to the reflective type photo-interrupter. Instead, a photo-sensor, a photo-coupler, or such, may be applied.  
         [0000]     [Operation] 
         [0090]      FIGS. 5 and 6  illustrate operation of the first embodiment of the present invention described above.  
         [0091]     When the paper is to be loaded, as shown in  FIG. 5 (A), the platen roller  114  is to be removed from the paper guide block  113 . In a state in which the platen roller  114  is removed from the paper guide block  113 , the coil springs  115  are pressed in the arrow θ 1  direction.  
         [0092]     In this state, the heat sensitive paper  141  is to be placed on the paper guide part  121   a  of the paper guide block  113 , as shown in  FIG. 5 (B). Next, as shown in  FIG. 6 (A), the platen roller  114  is to be mounted in the paper guide block  113 . At this time, the rotating shaft  114   a  of the platen roller  114  is pressed into the beating parts  132  of the paper guide block  113  from the arrow Z 1  direction to the arrow Z 2  direction. Thereby, the paper guide block  113  rotates in the arrow θ 2  direction against a resilient force of the springs  115 . As a result of the paper guide block  113  rotating in the arrow θ 2  directions against the resilient force of the springs  115 , the bottom surface of the paper guide part  131  comes into contact with the base part  121  of the frame  111 , and thus, the rotation of the paper guide block  113  is inhibited.  
         [0093]     When the platen roller  114  is released after the platen roller  114  is thus loaded in the bearings  132   a  of the paper guide block  113 , the resilient force of the coil springs  115  causes the paper guide block  113  to rotate in the arrow θ 1  direction. As a result, the platen roller  114  is pressed onto the printing head  112  in a condition in which the heat sensitive paper  114  is held therebetween, as shown in  FIG. 6 (B).  
         [0094]     When the reduction gear mechanism  117  rotates according to the rotation of the motor  116 , the platen roller  114  rotates in the arrow θ 1  direction. As a result of the platen roller  114  rotating in the arrow θ 1  direction, the heat sensitive paper  114  is fed in the arrow Z 1  direction. Printing on the heat sensitive paper  114  is carried out as a result of the heat sensitive paper  141  being thus fed in the arrow Z 1  direction and the printing head  112  being driven.  
         [0000]     [Effect] 
         [0095]     In this embodiment, as a result of the paper guide and the bearings of the platen roller  114  being thus integrally formed in the paper guide block  113 , the number of the components can be reduced. At this time, as a result of the paper guide block  113  being integrally molded of resin, it is possible that the rotating shaft  114   a  of the platen roller  114  can be directly received, and thus, it is possible to further reduce the number of components.  
         [0096]     Further, in this embodiment, the paper guide block  113  is rotatably held by the frame  111 , and the coil springs  115  inserted between the bottom surface of the paper guide block  113  and the base part  121  of the frame  111  press the paper guide block  113  in the direction of the printing head  112 . As a result, the printing head  112  can be fastened to the frame  111 , and thus, no space is required between the printing head  112  and the frame  111 . Alternatively, it is possible to utilize a space between the printing head  112  and the frame  111 , for example, for holding another device such as a card reader or such.  
         [0097]     Further, in this first embodiment, since the paper guide part  131  and the bearings  132  holding the platen roller  114  are integrally formed in the paper guide block  113 , it is possible to easily handle paper of a different width, merely by changing the width in the arrow X 1 , X 2  directions of the paper guide part  131  without changing the other portions.  
       Second Embodiment  
       [0098]      FIG. 7  shows a perspective view of a second embodiment of the present invention. In  FIG. 7 , the same reference numerals are given to parts/components the same as those of  FIG. 1 , and duplicate description is omitted.  
         [0099]     A printing apparatus  200  in the second embodiment is different from the first embodiment in a frame  211 , a printing head  212 , a paper guide block  213 , and a ground rod spring  214 . In the printing apparatus  200  in the second embodiment, the paper guide block  213  is fixed to the frame  111 , and the printing head  212  is pressed onto the paper guide block  213  by means of the ground rod spring  214 .  
         [0000]     [Frame  211 ] 
         [0100]      FIG. 8  shows a perspective view of the frame  211 . In the figure, the same reference numerals are given to the parts/components the same as those of  FIG. 2 , and the duplicated description is omitted.  
         [0101]     In the frame  211 , instead of the paper guide block  124 , a spring holding part  221  is formed in the arrow Y 1  direction side of the head holding part  122 . The spring holding part  221  is formed in such a manner that wall parts  211   a  are formed on arrow X 1 , X 2  direction end parts of the frame  211 . The ground rod spring  214  is held by the spring holding part  221 .  
         [0000]     [Printing Head  212 ] 
         [0102]      FIG. 9  shows a perspective view of the printing head  212 . In  FIG. 9 , the same reference numerals are given to parts/components the same as those of  FIG. 3 , and duplicate description is omitted.  
         [0103]     The printing head  212  has, on its both sides, projection parts  212   a  which engage with the paper guide block  213  swingably in the arrow Y 1 , Y 2  directions. The printing head  212  has a force applied thereto in the direction of the paper guide block  212  by means of the ground rod spring  214  which is inserted into the spring holding part  221  between the printing head  212  and the frame  211 .  
         [0104]     It is noted that the spring holding part  221  is configured in such a manner that a surface of the printing head  212  in the arrow Y 2  direction side comes into contact with the wall parts  211   a  of the frame  211 .  
         [0000]     [Paper Guide Block  213 ] 
         [0105]      FIG. 10  shows a perspective view of the paper guide block  213 . In  FIG. 10 , the same reference numerals are given to parts/components the same as those of  FIG. 4 , and duplicate description is omitted.  
         [0106]     The paper guide block  213  in the second embodiment is fixed to the frame  211 , and, has a head swinging part  213   a  which holds the printing head  212  in the bearing parts  132  swingably in the arrow Y 1 , Y 2  directions, instead of the holding part  133 .  
         [0000]     [Ground Rod Spring  214 ] 
         [0107]      FIG. 11  shows a perspective view of the ground rod spring  214 .  
         [0108]     The ground rod spring  214  has a configuration in which an electrically conductive elastic wire is bent, and has a pressing part  214   a,  connecting parts  214   b  and contacting parts  214   c.    
         [0109]     The pressing part  214   a  is loaded in the spring holding part  221  formed between the head holding part  122  of the frame  211  and the printing head  212 , and presses the printing head  212  in the direction of the platen roller  114 , i.e., in the arrow Y 1  direction. The connecting parts  214   b  extend along the arrow X 1 , X 2  directions from the both ends of the pressing part  214   a,  and are bent so that they extend to the both ends of the printing head  212 , then extend to a bottom part of the projection part  212   a  of the printing head  212  in the arrow Z 2  direction and then reach around the shaft of the platen roller  114 .  
         [0110]     The contacting parts  214   c  are provided at the extending ends of the connecting parts  214   b.  The contacting parts  214   c  come into contact with the rotating shaft  114   a  of the platen roller  114  when the platen roller  114  is loaded in the bearing parts  132  of the paper guide block  213 . The contacting parts  214   c  thus come into contact with the rotating shaft  114   a  of the platen roller  114 , and as a result, the platen roller  114  is connected with the ground rod spring  214 , and is grounded through the frame  211 . Thereby, electrostatic charge occurs due to friction of the heat sensitive paper or such can be discharged to the ground.  
         [0000]     [Operation] 
         [0111]      FIG. 12  illustrates operation of the second embodiment of the present invention.  
         [0112]     When paper is to be loaded, as shown in  FIG. 12 (A), the platen roller  114  is to be removed from the paper guide block  213 . When the platen roller  114  is thus removed from the paper guide block  213 , the printing head  212  is in a state in which it is pressed in the arrow Y 1  direction by means of the ground rod spring  214 .  
         [0113]     In this state, the heat sensitive paper  141  is to be placed in the paper guide part  121   a  of the paper guide block as shown in  FIG. 12 (B). Then, as shown in  FIG. 12 (C), the platen roller  114  is to be mounted in the paper guide block  213 . At this time, by means of the platen roller  114 , the printing head  212  is pressed in the arrow Y 2  direction against a resilient force of the ground rod spring  214  in a state in which the heat sensitive paper  141  is held. Thereby, the paper can be fed, and printing thereto can be made.  
       Third Embodiment  
       [0114]      FIG. 13  shows a perspective view of a third embodiment. In  FIG. 13 , the same reference numerals are given to parts/components the same as those of  FIG. 7 , and duplicate description is omitted.  
         [0115]     A printing apparatus  300  of the third embodiment is different from the second embodiment in a frame  311 , a printing head  212 , a paper guide block  313  and a U-spring  314 . In the printing apparatus  300 , the printing head  212  and the paper guide block  313  are fixed to the frame  311 , and the rotating shaft  114   a  of the platen roller  114  is pressed in the arrow Y 2  direction by means of the U-spring  314 . Thereby, the platen roller  114  and the printing head  212  hold the paper therebetween.  
         [0000]     [Frame  311 ] 
         [0116]      FIG. 14  shows a perspective view of the frame  311 . In  FIG. 14 , the same reference numerals are given to parts/components the same as those of  FIG. 8 , and duplicate description is omitted.  
         [0117]     The frame  311  is different from the frame  211  of the second embodiment in a configuration of a head holding part  322 . The head holding part  322  in the third embodiment has a shape such that a front surface thereof, i.e., the surface on the arrow Y 1  side projects forward, in the arrow Y 1  direction. The printing head  212  is fixed to the head holding part  322 .  
         [0000]     [Paper Guide Block  313 ] 
         [0118]      FIG. 15  shows a perspective view of the paper guide block  313 . In  FIG. 15 , the same reference numerals are given to parts/components the same as those of  FIG. 4 , and duplicate description is omitted.  
         [0119]     The paper guide block  313  in the third embodiment has a shape such that first projection parts  313   a  and second projection parts  313   b  are formed forward of outer side surfaces of the bearing parts  132 , i.e., on the arrow Y 1  direction side. The U-spring  314  engages with the first projection parts  313   a  and the second projection parts  313   b.    
         [0120]     The first projection parts  313   a  project at a top part of a front surface of the bearing parts  132 , outward, i.e., in the arrow X 1 , X 2  directions, and the U-spring  314  engages with the top ends thereof. The second projection parts  313   b  engage with a bottom side part of the U-spring  314 .  
         [0000]     [U-Spring  314 ] 
         [0121]     The U-spring  314  has a configuration in which a resilient wire is bent, and has pressing parts  314   a  and a connecting part  314   b.    
         [0122]     The pressing parts  314   a  have a U-shape, engage with the first projection parts  313   a  and the second projection parts  313   b  on the outside of the bearing parts  132  of the paper guide block  313 , have a force applied thereto in the arrow Y 1  direction when the platen roller  114  is loaded in the bearings  132   a,  and press the rotating shaft  114   a  of the platen roller  114  in the arrow Y 2  direction.  
         [0123]     The pressing parts  314   a  are connected with the connecting part  314   b  together. The connecting part  314   b  passes on the arrow Y 1  direction side end of the bearing part  132  of the paper guide block  313 , reaches the front surface end of the paper guide part  131  of the paper guide block  313 , and is led to the bearing part  132  of the other end.  
         [0124]      FIG. 17  shows a perspective view of a relevant part in a state in which the U-spring  314  is mounted on the paper guide block  313 .  
         [0125]     As shown in  FIG. 17 , the U-spring  314  presses the rotating shaft  114   a  of the platen roller  114  in the arrow Y 2  direction, and the roller  114   b  of the platen roller  114  is pressed onto the printing head  213 . Thereby, the roller  114   b  of the platen roller  114  and the printing head  213  can hold the heat sensitive paper therebetween.  
         [0000]     [Operation] 
         [0126]      FIG. 18  illustrates operation of the third embodiment.  
         [0127]     When the paper is to be loaded, the platen roller  114  is to be removed from the paper guide block  213  as shown in  FIG. 18 (A). In a state in which the printing head  212  is thus removed from the paper guide block  213  of the platen roller  114 , the pressing parts  314   a  of the U-spring  314  is released in the arrow Y 2  direction. Further, the bearings  132   a  of the paper guide block  313  are also released in the same manner.  
         [0128]     In this state, the heat sensitive paper  141  is to be placed on the paper guide part  121   a  of the paper guide block  313  as shown in  FIG. 18 (B). Next, as shown in  FIG. 18 (C), the platen roller  114  is to be mounted in the paper guide block  213 . As a result, the pressing parts  314   a  of the U-spring  314  are pressed by the rotating shaft  114   a  of the platen roller  114  in the arrow Y 1  direction, and along therewith, the rotating shaft  114   a  of the platen roller  114  has a force applied in the arrow Y 2  direction. As a result of the rotating shaft  114   a  of the platen roller  114  being thus pressed in the arrow Y 2  direction, the bearings  132   a  of the paper guide block  313  is deformed in the arrow Y 2  direction, and the roller  114   b  of the platen roller  114  is pressed onto the printing head  213  via the heat sensitive paper  141 .  
         [0129]     When the reduction gear mechanism  117  rotates along with rotation of the motor  116 , the platen roller  114  rotates in the arrow φ 1  direction. As a result of the platen roller  114  thus rotating in the arrow φ 1  direction, the heat sensitive paper  141  is fed in the arrow Z 1  direction. Along with the heat sensitive paper  141  being thus fed in the arrow Z 1  direction, the printing head  112  is driven, and thereby, printing is carried out on the heat sensitive paper  141 .  
       Fourth Embodiment  
       [0130]      FIG. 19  shows a perspective view of a fourth embodiment of the present invention. In  FIG. 19 , the same reference numerals are given to parts/components the same as those of  FIG. 7 , and duplicate description is omitted.  
         [0131]     A printing apparatus  400  in the fourth embodiment is different from the printing apparatus in the third embodiment in a configuration of a paper guide block  413 . Further, in the paper guide block  413  in the fourth embodiment, a configuration of bearing parts  432  is different from that of the paper guide block  313 .  
         [0000]     [Paper Guide Block  413 ] 
         [0132]      FIG. 20  shows a perspective view of the paper guide block  413 , and  FIG. 21  shows a perspective view of a relevant part of the paper guide block  413  during assembling. In the figures, the same reference numerals are given to parts/components the same as those of  FIG. 4 , and duplicate description is omitted.  
         [0133]     The paper guide block  413  has, U-grooves  432   d  instead of the slit parts  132   d.  The U-grooves  432   d  are formed to the bottom of the bearings  132   a,  i.e., in the arrow Z 2  direction. By means of the U-grooves  432   d,  the cut out parts  132   b  are easily opened in the arrow Y 1 , Y 2  directions when the rotating shaft  114   a  of the platen roller  114  is loaded in the bearings  132   a.    
       Fifth Embodiment  
       [0134]      FIG. 22  shows a perspective view of a fifth embodiment of the present invention. In  FIG. 22 , the same reference numerals are given to parts/components the same as those of  FIG. 1 , and duplicate description is omitted.  
         [0135]     A printing apparatus  500  in the fifth embodiment is different from the first embodiment in configurations of a frame  511  and a paper guide block  513 . The frame  511  and the paper guide block  513  together hold the shaft  114   a  of the platen roller  114  in this embodiment.  
         [0000]     [Frame  511 ] 
         [0136]      FIG. 23  shows a perspective view of the frame  511 .  
         [0137]     The frame  511  in the present embodiment is different from that of the first embodiment in that engaging parts  521  are provided on both ends in the arrow X 1 , X 2  directions for engaging with the shaft  114   a  of the platen roller  114 . In bearing parts  521 , U-grooves  521   a  and guide parts  521   b  are formed.  
         [0138]      FIG. 24  shows a perspective view of a paper guide block  513 .  
         [0139]     The paper guide block  513  in this embodiment is different from that of the first embodiment in that bearing parts  532  are provided. The bearing parts  532  have U-grooves  532   a  and guide parts  532   b.    
         [0000]     [Operation] 
         [0140]      FIG. 25  illustrates operation of the fifth embodiment.  
         [0141]     When paper is to be loaded, as shown in  FIG. 25 (A), the platen roller  114  is to be removed from the paper guide block  513 . In the state in which the platen roller  114  is thus removed from the paper guide block  513 , the paper guide block  513  is in a state in which it rotates in the arrow θ 1  direction.  
         [0142]     The heat sensitive paper  141  is to be placed in the guide part  131  in this state as shown in  FIG. 25 (B). Next, as shown in  FIG. 25 (B), the rotating shaft  114   a  of the platen roller  114  is to be pressed in the arrow Z 2  direction along the guide parts  521   b  and the guide-parts  523   b.  Thereby, as shown in  FIG. 25 (C), the paper guide block  513  rotates in the arrow θ 2  direction against a resilient force of the coil springs  115 , and is loaded between the U-grooves  521   a  and the U-grooves  532   a.    
         [0143]     At this time, the U-grooves  532   a  are formed in such a direction that, by means of friction of the heat sensitive paper as shown in  FIG. 25 (C), the rotating shaft  114   a  of the platen roller  114  can be positively held in a direction of a resultant force F 3  of a force F 1  applied to the platen roller  114  and a force F 2  applied to the gear  114   c.    
       Sixth Embodiment  
       [0144]      FIG. 26  shows a perspective view of a sixth embodiment of the present invention. In  FIG. 26 , the same reference numerals are given to parts/components the same as those of  FIG. 7 , and duplicate description is omitted.  
         [0145]     A printing apparatus  600  in the sixth embodiment is different from the second embodiment in configurations of a paper guide block  613  and a rod spring  614 . The paper guide block  613  and the rod spring  614  hold the rotating shaft  114   a  of the platen roller  114  in this embodiment.  
         [0146]      FIG. 27  shows a perspective view of the paper guide block  613 . In  FIG. 27 , the same reference numerals are given to parts/components the same as those of  FIG. 7 , and duplicate description is omitted.  
         [0147]     The paper guide block  613  in this embodiment is different from that of the second embodiment in a configuration of bearings  632 . The bearings  632  have U-grooves  632   a  and guide parts  632   b.    
         [0148]      FIG. 28  shows a perspective view of the rod spring  614 . In  FIG. 28 , the same reference numerals are given to parts/components the same as those of  FIG. 8 , and duplicate description is omitted.  
         [0149]     In the rod spring  614 , instead of the contacting part, claw parts  614   a  are provided. The claw parts  614   a  engage with the rotating shaft  114   a  of the platen roller  114 , so as to press the rotating shaft  614   a  of the platen roller  114  onto the U-grooves  632   a  provided in the bearings  632  of the paper guide block  613 .  
         [0000]     [Operation] 
         [0150]      FIG. 29  illustrates operation of the sixth embodiment.  
         [0151]     When paper is to be loaded, as shown in  FIG. 29 (A), the platen roller  114  is to be removed from the paper guide block  613 . When the platen roller  114  is thus removed from the paper guide block  613 , the paper guide block  613  is in a state in which it rotates in the arrow θ 1  direction.  
         [0152]     In this state, the heat sensitive paper  141  is to be placed on the paper guide part  131  of the paper guide block  613 . Next, as shown in  FIG. 28 (B), the rotating shaft  114   a  of the platen roller  114  is to be pressed in the arrow Z 2  direction along the claw parts  614   a  and the guide parts  632   b.  Thereby, as shown in  FIG. 29 (C), the claw parts  614   a  are elastically pressed in the arrow Y 2  direction, and the rotating shaft  114   a  of the platen roller  114  is loaded in the U-grooves  632   a.  When the rotating shaft  114   a  of the platen roller  114  is thus pressed in the U-grooves  632   a,  the claw parts  614   a  return in the arrow Y 1  direction, the rotating shaft  114   a  of the platen roller  114  is pressed thereby into the U-grooves  632   a,  and thus, the platen roller  114  is rotatably held there.  
         [0000]     [Others] 
         [0153]     In each of the above-mentioned embodiments, the paper guide block and the gear cover are configured in separate bodies. However, in each of the second through fourth embodiments, the paper guide block is fixed to the frame. Accordingly, the paper guide block and the gear cover may be integrally formed.  
         [0154]     Further, in the above-mentioned embodiments, it is possible to save space, in particular, to reduce a space in the arrow Y 1 , Y 2  directions, and thus, it is possible to create a space between the frame  111  and the motor  116  for example. Thereby, it is possible to hold a card reader or such there, and thus, it is possible to create a multi-function apparatus.  
       Seventh Embodiment  
       [0155]      FIG. 30  shows a front perspective view of a seventh embodiment of the present invention;  FIG. 31  shows a rear perspective view of the seventh embodiment of the present invention;  FIG. 32  shows a bottom perspective view of the seventh embodiment of the present invention;  FIG. 33  shows a plan perspective view of the seventh embodiment of the present invention; and  FIG. 34  shows a sectional view of the seventh embodiment of the present invention.  
         [0156]     A printing apparatus  700  in the seventh the embodiment includes a base frame  711 , a motor  712 , a reduction gear mechanism  713 , a printing head  714 , an FPC cable  715 , a pressing spring  716 , a paper guide block  717 , a platen roller  718 , a sensor  719  and so forth. It is noted that the printing head  714  has the same configuration as that of the printing head  212  shown in  FIG. 9 .  
         [0000]     [Base Frame] 
         [0157]      FIG. 35  shows a front perspective view of the base frame  711 ;  FIG. 36  shows a rear perspective view of the base frame  711 ; and  FIG. 37  shows a bottom perspective view of the base frame  711 .  
         [0158]     The base frame  711  has a configuration such that a motor mounting part  721 , a reduction gear mechanism mounting part  722 , a pressing spring mounting part  723 , a paper guide block mounting part  724  and a printing head retreating part  725  are integrally formed in a die-cast molding manner.  
         [0159]     In the motor mounting part  721 , the motor  721  is mounted. In the reduction gear mechanism mounting part  722 , gears included in the reduction gear mechanism  713  are loaded. The pressing spring mounting part  723  is located on a bottom side of the printing head  714 , and therein, the pressing spring  716  pressing the printing head  714  in the direction of the platen roller  18  is loaded.  
         [0160]     The paper guide block mounting part  724  is engaged with by the paper guide block  717 , and is used for mounting the base frame  711  between the paper guide block  717 . In the paper guide block mounting part  724 , a mounting hole  724   a  is formed. In the mounting hold  724   a,  a screw is inserted when the apparatus is mounted on a to-be-mounted part.  
         [0161]     The motor  712  is mounted to the motor mounting part  721 , the gears of the reduction gear mechanism  713  are mounted to the reduction gear mechanism mounting part  722 , and thus, the motor  712  engages with the reduction gear mechanism  713 .  
         [0162]     The printing head retreating part  725  is formed at a part with which the paper guide block  717  engages, and is used for retreating so that, when the paper guide block  717  is mounted to the base frame  711 , the projection parts  112   a  of the printing head  714  are prevented from being held between the paper guide block  717  and the base frame  711 . With the provision of the printing head retreating part  725 , assembling can be made easily.  
         [0000]     [Paper Guide Block  717 ] 
         [0163]      FIG. 38  shows a front perspective view of the paper guide block  717 ;  FIG. 39  shows a rear perspective view of the paper guide block  717 ; and  FIG. 40  shows a bottom perspective view of the paper guide block  717 .  
         [0164]     The paper guide block  717  is produced by a resin material molding manner. The paper guide block  717  includes platen roller bearing parts  731 , paper guide part  732 , an engaging part  733  and a gear cover part  734 . Thereto, the printing head  714  and the platen roller  718  are loaded.  
         [0165]     The platen roller bearing parts  731  are provided on the arrow X 1 , X 2  direction ends, and rotatably hold the platen roller  718 . The platen roller bearing parts  731  include bearings  731   a  and claw parts  731   b,  and further, printing head guide parts  731   c.    
         [0166]     The bearings  731   a  are formed in approximately U-shapes, and rotatably hold the rotating shaft of the platen roller  718 . The claw parts  731   b  are formed in arrow A 1 , A 2  directions elastically and deformably, and, when the shaft of the platen roller  718  is loaded in the bearings  731   a,  they are deformed in the arrow A 1  direction, after that, return in the arrow A 1  direction, and they press the rotating shaft of the platen roller  718  to the bearings  713   a.  By this configuration, the platen roller  718  can be easily mounted/removed to/from the paper guide block  717 . Thus, replacement of paper can be easily made.  
         [0167]     The printing head guide parts  731   c  are formed in such a manner as to be able to communicate with the printing head retreating parts  725 , and engage with the projection parts  112   a  of the printing head  714 . The projection parts  112   a  of the printing head  714  engage with the printing head guide parts  713   c  and the printing head  714  is positioned swingably with respect to the platen roller  718   
         [0168]     The paper guide part  732  is placed horizontally on the arrow Z 2  direction side of the platen roller bearing parts  731  along the arrow X 1 , X 2  directions, and functions to guide the paper inserted from the arrow Y 1  direction when the paper passes between the platen roller  718  and the printing head  714  in a curled manner.  
         [0169]     In the paper guide part  732 , through holes  732   a,  substrate holding parts  732   b  and engaging claw parts  732   c  are formed. A sensor for detecting existence/absence of paper and the platen roller  718 , is disposed on the bottom side of the through holes  732   a,  i.e., on the surface on the arrow Z 2  direction side. The sensor detects existence/absence of paper and the platen roller  718  through the through holes  732   a.    
         [0170]      FIG. 41  shows a sectional perspective view of a relevant part of the seventh embodiment.  
         [0171]     On the substrate holding parts  732   b,  a sensor substrate  741  on which the sensor  719  is mounted is held. The engaging claw parts  732   c  engage with the arrow Y 1  direction side of the arrow Z 2  direction end part of the paper guide block mounting part  724  of the base frame  711 .  
         [0172]     The engaging part  733  includes a vertically placing part  733   a  and engaging claw parts  733   b.  The vertically placing part  733   a  is vertically placed on the arrow Z 1  direction end of the arrow Y 2  direction end side of the platen roller bearing parts  731  along the arrow X 1 , X 2  directions. The engaging claw parts  733   b  extend in the arrow Z 2  direction, and engage with the arrow Y 2  direction side of the arrow Z 2  direction end side of the printing head mounting part  723  of the base frame  711 . Thereby, the paper guide block  717  hold the base frame  711  by means of the engaging claw parts  732   c,    733   b,  and is mounted on the base frame  711 .  
         [0173]     The gear cover  734  is disposed on the arrow X 1  direction side of the reduction gear mechanism  713 , and avoids removal of the gears of the reduction gear mechanism  713  in the arrow X 1  direction.  
         [0000]     [Advantage] 
         [0174]     In the seventh embodiment, the platen roller bearing parts  731  for rotatably holding the platen roller  718  in the paper guide block  717  and the printing head guide parts  731   c  for positioning the printing head  714  are formed integrally. Thereby, the paper guide block  717  positions the platen roller  718  and the printing head  714 . Accordingly, even when a shape of the paper guide block  717  is changed, the common base frame  711  can be applied, and thus, the common base frame  711  can be applied to various types.  
       First Variant Embodiment  
       [0175]      FIG. 42  shows a front perspective view of a first variant embodiment of the seventh embodiment;  FIG. 43  shows a rear perspective view of the first variant embodiment of the seventh embodiment;  FIG. 44  shows a bottom perspective view of the first variant embodiment of the seventh embodiment;  FIG. 45  shows a plan view of the first variant embodiment of the seventh embodiment;  FIG. 46  shows a sectional view of the first variant embodiment of the seventh embodiment; and  FIG. 47  shows a sectional view of a relevant part of the first variant embodiment of the seventh embodiment. In these figures, the same reference numerals are given to the same components/parts as those in  FIGS. 30 through 32 , and duplicate description is omitted.  
         [0176]     A printing apparatus  800  in this variant embodiment has a configuration such that, in the printing apparatus  700  in the seventh embodiment, the base frame  711  is common, the shape of the paper guide block  717  is changed, and a paper outputting direction is inclined by an angle θ 11  with respect to the arrow Z 1 , Z 2  directions. It is noted that, for the purpose that the paper outputting direction is thus inclined, the base frame  711  is disposed in an inclined manner accordingly.  
         [0177]      FIG. 48  shows a front perspective view of the paper guide block  811 ;  FIG. 49  shows a rear perspective view of the paper guide block  811 ; and  FIG. 50  shows a bottom perspective view of the paper guide block  811 . In these figures, the same reference numerals are given to the same components/parts as those in  FIGS. 38 through 40 , and duplicate description is omitted.  
         [0178]     In the paper guide block  811 , the bearing parts  731  are disposed in such a manner as to be inclined by the angle θ 11 , and a cover part  821  is provided. The cover part  721  covers the surface of the apparatus on the arrow Z 1 , Y 2  direction side. By means of providing the cover part  821 , the apparatus can be handled as a separate miniaturized printing apparatus.  
         [0179]     Further, in this variant embodiment, a mounting hole  822  is formed at a central part of the paper guide block  732 . By screwing a screw into a to-be-mounted part through the mounting hole  822  of the paper guide block  811  and the mounting hole  724   a  of the base frame  711 , the printing apparatus  800  is fixed to the to-be-mounted part. Thereby, it is possible to improve connectedness between the paper guide block  811  and the base frame  711 .  
         [0180]     Further, in this variant embodiment, a configuration is provided such that paper can be made to pass straightly. At this time, a sensor substrate mounting part  823  for mounting a sensor substrate for paper detection is formed on the paper guide part  732 . On the sensor substrate mounting part  823 , the sensor substrate  832  on which a sensor  831  is mounted is mounted. The sensor  831  faces in the arrow Y 2  direction, and can detect the paper inserted in the arrow Z 1  direction from a paper inserting hole  841 .  
         [0181]     In this variant embodiment, since, instead of the FPC cabled  715 , a circuit substrate on which a connector, an interface circuit, a processing circuit and so forth are mounted is provided in such a manner as being accommodated in the cover part  821 . Thus, the apparatus can be handled as the separate miniaturized printing apparatus.  
       Second Variant Embodiment  
       [0182]      FIG. 51  shows a perspective view of a second variant embodiment of the seventh embodiment; and  FIG. 52  shows a sectional view of a relevant part of the second variant embodiment of the seventh embodiment.  FIG. 52 (A) shows a state in which a platen roller  718  is loaded; and  FIG. 52 (B) shows a state in which the platen roller  718  is removed. In the figures, the same reference numerals are given to the same components/parts as those in  FIGS. 30 through 32 , and duplicate description is omitted.  
         [0183]     In a printing apparatus  900  in this variant embodiment, a configuration of a paper guide block  911  is different from that of the seventh embodiment. The paper guide block  911  of this variant embodiment includes a base part  921  and a movable paper guide part  922 , and further, coil springs  923 .  
         [0184]     The base part  921  is integrally molded together with the paper guide block  911 . On the base part  921 , a sensor  719  is held. The movable paper guide part  922  is configured as a separate body from the paper guide block  911 , and is coupled to the base part  921  through the coil springs  923 .  
         [0185]     In a state in which the platen roller  718  is loaded in the paper guide block  911 , as shown in  FIG. 52 (A), the movable paper guide part  922  is held by the platen roller  718  in a state such that it is pressed in the arrow Z 2  direction by the platen roller  718 , and a distance of the surface of the movable paper guide part  922  from the sensor is d 0 . At this time, paper P is in a state such that it is held between the platen roller  718  and the movable guide part  922 , and thus, a distance of the paper P from the sensor  719  is d 0 .  
         [0186]     When the platen roller  718  is then removed from the paper guide block  911 , the coil springs are released as shown in  FIG. 52 (B), and the movable paper guide part  922  is lifted in the arrow Z 1  direction. Thereby, the distance of the surface of the movable paper guide part  922  from the sensor  719  becomes (d 0 +α). As a result of the movable paper guide part  922  being lifted in the arrow Z 1  direction, the paper P is located at least at a position separate from the sensor  719  by (d 0 +α).  
         [0187]     Accordingly, by detecting a change in the output of the sensor  719  for the distance, existence/absence of the platen roller  718  can be detected.  
         [0000]     [Others] 
         [0188]     It is noted that, in this variant embodiment, existence/absence of the platen roller  718  is detected from a change in the output of the sensor  719  according to the distance. However, existence/absence of paper P, a paper position mark M, and/or the platen roller  718  may be detected from difference in the reflectivity. It is noted that, the paper position mark M is a mark having a predetermined width printed on the paper P, and indicates position information such as a starting position or an end position of the paper P or such.  
         [0189]     For example, the paper P is made of a white material, the paper position mark M is made of a black material, and the platen roller  718  is made of a gray material, for example. Then, when the paper P is located on the sensor  719 , the output of the sensor  719  becomes high level since the paper P is white and the light reflectivity is high. Thus, when the output of the sensor  719  is high, it is determined that the paper P exists.  
         [0190]     When the paper position mark M is located on the sensor  719 , the output of the sensor  719  becomes low level since the paper position mark M is black and the light reflectivity is low. Further, the paper position mark M has the predetermined width, and before and after that is white. Thus, when the low output of the sensor  719  continues for a predetermined time period, it is determined that the paper position mark M exists.  
         [0191]     When no paper P is located on the sensor  719 , but the platen roller  718  is located there, the output of the sensor  719  becomes intermediate level between the high level and the low level, since the platen roller  718  is gray and the light reflectivity is intermediate between those of white and black. Thus, when the output of the sensor  719  is the intermediate level, it is determined that no paper P exists, but the platen roller is loaded.  
         [0192]     Further, when the output of the sensor  719  continues to have the low level for more than the predetermined time period, it is determined that neither the paper P nor the platen roller  718  exists on the sensor  719 .  
         [0193]     Further, the present invention is not limited to the above-described embodiments, and variations and modifications may be made without departing from the basic concept of the present invention claimed below.  
         [0194]     The present application is based on Japanese Priority Applications Nos. 2005-182502 and 2005-212737, filed on Jun. 22, 2005 and Jul. 22, 2005, respectively, the entire contents of which are hereby incorporated herein by reference.