Patent Publication Number: US-11040554-B2

Title: Printer including first link, second link, and connection member for moving platen holder in accordance with movement of operation member

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority from Japanese Patent Application No. 2019-109647 filed Jun. 12, 2019. The entire content of the priority application is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a printer. 
     BACKGROUND 
     There has been known a printer in which a positional relationship between a platen roller and a printing head is changed in accordance with a pivotal movement of a cover. For example, Japanese Patent Application No. H04-166373 discloses a facsimile including a cover member and a release cam. In this facsimile, an engagement pin of the cover member is releasably engaged with an engagement groove formed in the release cam to transmit a force generated by an opening/closing operation of the cover member to the release cam. As the release cam is pivotally moved, a recording head is moved in a direction away from a platen or approaches the platen. 
     SUMMARY 
     With the facsimile described above, however, the engagement pin is brought into disengagement from the engagement groove during the opening operation of the cover member. Therefore, if a posture of the release cam has been changed for some reason while the cover member is open, the engagement pin may fail to be engaged with the engagement groove in the closing operation of the cover member. That is, this configuration may hinder the positional relationship between the platen and the recording head from being stably changed in accordance with the opening/closing operation of the cover member. 
     In view of the foregoing, it is an object of the present disclosure to provide a printer in which a positional relationship between a platen roller and a printing head can be stably changed in accordance with a movement of an operation member operated by a user. 
     In order to attain the above and other objects, according to one aspect, the disclosure provides a printer including: a housing; a platen holder; a platen roller; a printing head; an operation member; a first link; a second link; a connection member; and a movable member. The platen holder is accommodated in the housing and is movable between a pressure position and a retracted position. The platen roller is rotatably supported by the platen holder. The printing head is configured to nip a printing medium in cooperation with the platen roller to perform printing on the printing medium. The platen roller presses the printing head when the platen holder is at the pressure position. The platen roller is spaced apart from the printing head when the platen holder is at the retracted position. The operation member is provided at the housing and is movable relative to the housing within a first movable range and within a second movable range different from the first movable range. The first link is pivotally movably supported by the operation member. The first link has a first portion and a second portion different from the first portion. The second link is supported by the housing and is pivotally movable between an operation position and a standby position. The connection member has a connecting portion at which the first link and the second link are connected to each other. The first link and the connecting portion provides therebetween a positional relationship including a first positional relationship at the first portion of the first link and a second positional relationship at the second portion of the first link. The movable member is movable in interlocking relation to a pivotal movement of the second link from the operation position to the standby position to move the platen holder from the pressure position to the retracted position. When the operation member is moved within the first movable range, the connection member causes the second link to be pivotally moved from the operation position to the standby position in response to a pivotal movement of the first link while maintaining the first positional relationship between the first link and the connecting portion. When the operation member is moved within the second movable range, the connection member causes the positional relationship between the first link and the connecting portion to be changed from the first positional relationship to the second positional relationship in response to the pivotal movement of the first link while maintaining the second link at the standby position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The particular features and advantages of the embodiment(s) as well as other objects will become apparent from the following description taken in connection with the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a printer according to one embodiment of the present disclosure and a tape cassette attachable to the printer; 
         FIG. 2  is a perspective view of a platen holder, a platen roller, and a conveying roller in the printer according to the embodiment; 
         FIG. 3  is a perspective view of a first link, a second link, and a movable member in the printer according to the embodiment; 
         FIG. 4A  is an explanatory view for explaining how a cover in the printer according to the embodiment is moved within a first movable range, and particularly illustrating a state where the cover is in its closed position and the second link is in its operation position; 
         FIG. 4B  is an explanatory view for explaining how the cover in the printer according to the embodiment is moved within the first movable range, and particularly illustrating a state where the first link is pivotally moved by an amount of a clearance provided between a first cam formed in the first link and a pin provided on the second cam; 
         FIG. 4C  is an explanatory view for explaining how the cover in the printer according to the embodiment is moved within the first movable range, and particularly illustrating a state where the second link is in its standby position; 
         FIG. 5A  is an explanatory view for explaining how the cover in the printer according to the embodiment is moved within a second movable range, and particularly illustrating a state where the pin is slidingly moved relative to a groove cam formed in the first link; 
         FIG. 5B  is an explanatory view for explaining how the cover in the printer according to the embodiment is moved within the second movable range, and particularly illustrating a state where the cover is in its open position; 
         FIG. 6  is a perspective view of the first link in the printer according to the embodiment, and particularly illustrating a state prior to assembly of the first link to the second link and the cover; and 
         FIG. 7  is a right side view of a set of pins provided on a second link in a printer according to a modification. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, one embodiment of the present disclosure will be described while referring to the accompanying drawings. Note that the terms “upward”, “downward”, “leftward”, “rightward”, “frontward” and “rearward” appearing in the following description correspond to the terms “up”, “down”, “left”, “right”, “front” and “rear” shown in the drawings, respectively. 
     First, a configuration of a printer  1  according to the embodiment will be described with reference to  FIGS. 1 to 4C . As illustrated in  FIG. 1 , the printer  1  includes a housing  2  having a substantially rectangular parallelepiped shape. The housing  2  is formed with an attachment portion  8  that is open upward. A tape cassette  60  including a printing medium  5  is attachable to and detachable from the attachment portion  8 . Further, a right portion of a front surface of the housing  2  is formed with a discharge opening  11  that allows the printing medium  5  to be discharged outside of the housing  2  therethrough. A cutting mechanism (not illustrated) is disposed within the housing  2  at a position rearward of the discharge opening  11 . The cutting mechanism is configured to cut the printing medium  5 . The attachment portion  8  is an example of an opening. 
     In one example, the tape cassette  60  is a receptor type. The tape cassette  60  has support holes  65  and  67  and a head opening  69 , and includes a ribbon take-up spool  68  and a tape drive roller  46 . Although not illustrated in the drawings in detail, the support hole  65  rotatably supports a tape spool around which the printing medium  5  is wound, and the support hole  67  rotatably supports a ribbon spool around which an unused ribbon is wound. The ribbon take-up spool  68  has a hollow cylindrical shape and is rotatable to take up a used ribbon. The tape drive roller  46  has a hollow cylindrical shape and is rotatable. The head opening  69  penetrates the tape cassette  60  in an up-down direction, and is open rightward. Within the head opening  69 , the ribbon and the printing medium  5  are superposed on each other so that the ribbon is positioned to the left of the printing medium  5 . 
     As illustrated in  FIG. 1 , the housing  2  includes an auxiliary shaft  118  extending upward from a bottom portion of the attachment portion  8 . Further, as illustrated in  FIG. 2 , a support plate  32  is provided at a position below the bottom portion of the attachment portion  8 . A ribbon take-up shaft  95 , a drive shaft  100 , and a head holder  74  are provided on the support plate  32  so as to extend upward from the support plate  32  into the attachment portion  8 . 
     In a state where the tape cassette  60  is attached to the attachment portion  8 , the ribbon take-up shaft  95  is inserted into the ribbon take-up spool  68 , the auxiliary shaft  118  is inserted into the support hole  65 , and the drive shaft  100  is inserted into the tape drive roller  46 . In this state, the ribbon take-up shaft  95  and the drive shaft  100  are drivingly connected to a conveying motor  33  (see  FIG. 2 ) provided on the support plate  32 . 
     Further, in the state where the tape cassette  60  is attached to the attachment portion  8 , the head holder  74  is inserted into the head opening  69 , and the printing medium  5  is accommodated in the attachment portion  8 .  FIG. 2  illustrates a printing head  10  provided on a right surface of the head holder  74 . In the present embodiment, the printing head  10  a thermal head provided with a plurality of heat generating elements arranged in the up-down direction. 
     A platen holder  12  is accommodated within the housing  2 . The platen holder  12  extends in a front-rear direction, and has a rear end portion pivotally movably supported by a support shaft  35  provided on the support plate  32 . Specifically, the platen holder  12  is pivotally movable about the support shaft  35  between a pressure position (see  FIG. 2 ) and a retracted position. The platen holder  12  rotatably supports a platen roller  64  and a conveying roller  66 . The platen roller  64  is positioned to face the printing head  10 . In a state where the tape cassette  60  is attached to the attachment portion  8 , the conveying roller  66  faces the tape drive roller  46  of the tape cassette  60 . 
     When the platen holder  12  is in the pressure position, the platen roller  64  presses the printing head  10 , and the conveying roller  66  presses the tape drive roller  46 . In this state, the printing medium  5  and the ribbon superposed on each other are nipped at a portion between the platen roller  64  and the printing head  10  while the ribbon is positioned rightward of the printing medium  5 . Further, the printing medium  5  is nipped at a portion between the conveying roller  66  and the tape drive roller  46 . The ribbon is conveyed to an inner space of the tape cassette  60  through a portion between the head opening  69  and the tape drive roller  46 , and is taken up by the ribbon take-up spool  68 . 
     When the platen holder  12  is in the retracted position, the platen roller  64  is positioned rightward of the printing head  10  to be spaced apart from the printing head  10 , and the conveying roller  66  is positioned rightward of the tape drive roller  46  to be spaced apart from the tape drive roller  46 . As the platen holder  12  is pivotally moved from the retracted position to the pressure position, the platen roller  64  is brought into driving connection to the conveying motor  33 . 
     An inclined portion (not illustrated) is provided on a right end portion of the platen holder  12 . The inclined portion is inclined frontward as extending from the left side toward the right side. The platen holder  12  is urged by a torsion spring (not illustrated) in the counterclockwise direction toward the retracted position about the support shaft  35  as viewed in a plan view. This configuration causes the inclined portion of the platen holder  12  to be pressed against a rotary roller  82  (see  FIG. 3 ) provided in a movable member  150  (described later). 
     As illustrated in  FIG. 1 , a pair of pivot portions  71  is provided at a rear portion of the housing  2 . Each of the pair of pivot portions  71  has a substantially U-shape as viewed in a front view. The pair of pivot portions  71  respectively supports a pair of shafts  72  each extending in a left-right direction. The pair of shafts  72  supports a cover  6  so as to be pivotally movable relative to the housing  2 . The cover  6  can open and close the attachment portion  8  that serves an opening accommodating therein the printing medium  5  in accordance with a pivotal movement of the cover  6 . 
     In response to a user&#39;s operation, the cover  6  is pivotally movable between a closed position (see  FIG. 4A ) and an open position (see  FIG. 1 ). When the cover  6  is in the open position, the attachment portion  8  is open upward. When the cover  6  is in the closed position, the attachment portion  8  is closed by the cover  6 . The cover  6  is an example of an operation member. 
     In the following description, of a range within which the cover  6  is pivotally movable (hereinafter also simply referred to as “movable range”), a movable range that includes the closed position of the cover  6  is referred to as “first movable range”, and a movable range that includes the open position of the cover  6  is referred to as “second movable range”. The first movable range is a range within which the cover  6  is pivotally moved as illustrated in  FIGS. 4A to 4C , whereas the second movable range is a range within which the cover  6  is pivotally moved as illustrated in  FIGS. 5A and 5B . The second movable range is different from the first movable range. 
     As illustrated in  FIG. 1 , a pair of bearing portions  7  arranged in the left-right direction is provided on the cover  6 . Each of the pair of bearing portions  7  protrudes frontward in a state where the cover  6  is in the open position. Each of the pair of bearing portions  7  is formed of resin and is formed integrally with the cover  6 . Each of the pair of bearing portions  7  is a plate like member having a rectangular shape as viewed in a side view, and has a protruding end portion formed with a pivot hole  7 A penetrating the same in the left-right direction. 
     Next, a configuration for connecting the cover  6  and the platen holder  12  to each other will be described with reference to  FIGS. 1 to 4A . The cover  6  and the platen holder  12  are connected to each other via a first link  110 , a second link  220 , and the movable member  150 . 
     As illustrated in  FIGS. 2 and 3 , the first link  110  extends perpendicularly to the left-right direction while curving. The first link  110  has one end portion at which a pair of shaft portions  111  protruding outward in the left-right direction is provided. Each of the pair of shaft portions  111  is movably fitted into the corresponding one of the pair of pivot holes  7 A (see  FIG. 1 ). With this configuration, the first link  110  is supported by the cover  6  so as to be pivotally movable in interlocking relation to the pivotal movement of the cover  6 . 
     As illustrated in  FIGS. 3 and 4A , the first link  110  has another end portion at which a cam portion  130  is provided. In the present embodiment, the cam portion  130  is a hole that penetrates the first link  110  in the left-right direction, and includes a first cam  131 , a second cam  132 , and a groove cam  133 . 
     The first cam  131  has a substantially circular arc shape formed in a first portion in the first link  110 . In the present embodiment, the first portion corresponds to a point P 1  in the first link  110  illustrated in  FIG. 4A . The second cam  132  is provided in a second portion in the first link  110 , and has a circular are shape substantially identical to the shape of the first cam  131 . For example, the second portion corresponds to a point P 2  in the first link  110  illustrated in  FIG. 4A . The first portion and the second portion are displaced in accordance with a pivotal movement of the first cam  131 . The groove cam  133  extends from the first cam  131  to the second cam  132  (i.e., to the second portion) to connect the first cam  131  and the second cam  132  to each other. The groove cam  133  has a shape that curves slightly frontward relative to an imaginary line connecting the point P 1  to the point P 2 . The groove cam  133  has a groove width (a dimension W) smaller than an inner diameter (a dimension D) of the first cam  131 . 
     Also, the first link  110  includes a protruding portion  119  (see  FIG. 4A ). The protruding portion  119  has a circular columnar shape and protrudes rightward at a position between the pair of shaft portions  111  and the cam portion  130 . 
     As illustrated in  FIG. 3 , the second link  220  is pivotably movably supported by a pivot shaft  281  of a right plate  280  provided in an inner right portion of the housing  2  (see  FIG. 1 ). That is, the second link  220  is pivotably movably supported by the housing  2 . The second link  220  has a substantially L-shape as viewed in a side view, and includes a base portion  223 , a first arm  221 , and a second arm  222 . The base portion  223  is formed with a through-hole (not illustrated) into which the pivot shaft  281  is fitted. With this configuration, the base portion  223  is rotatable about the pivot shaft  281 . Each of the first arm  221  and the second arm  222  protrudes from the base portion  223 . 
     The first arm  221  has a distal end portion on which a pin  228  is provided. Further, the second arm  222  has a distal end portion formed with a slot  229  extending substantially parallel to a direction in which the second arm  222  extends. The pin  228  protrudes from the distal end portion of the first arm  221 , and is engaged with the cam portion  130 . The pin  228  has an oblong cross-section taken along a plane perpendicular to the left-right direction in which a center axis  228 A of the pin  228  extends. The pin  228  has a major diameter (a dimension S 1 ) smaller than the inner diameter (the dimension D) of the first cam  131  and greater than the groove width (the dimension W) of the groove cam  133 , and a minor diameter (a dimension S 2 ) smaller than the groove width of the groove cam  133 . The pin  228  is an example of a connecting portion of a connection member. 
     In the following description, the cam portion  130  and the pin  228  will also be correctively referred to as “connection member  88 ”. The first link  110  and the second link  220  are connected to each other via the connection member  88 . 
     An extension portion  225  (see  FIG. 4A ) is also provided on the distal end portion of the first arm  221 . The extension portion  225  extends in a direction away from the pivot shaft  281 . The pivot shaft  281  and the extension portion  225  provides a distance greater than a distance between the pivot shaft  281  and the pin  228 . In other words, the extension portion  225  is positioned farther from the pivot shaft  281  than the pin  228  is from the pivot shaft  281  which serves as a pivot center of the second link  220 . The extension portion  225  can abut against the protruding portion  119  of the first link  110 . 
     Owing to the engagement of the pin  228  with the cam portion  130 , the second link  220  is pivotally movable about the pivot shaft  281  between an operation position (see  FIG. 4A ) and a standby position (see  FIG. 4C ) in accordance with a pivotal movement of the first link  110 . When the second link  220  is in the operation position, a direction of the major diameter of the pin  228  (hereinafter also referred to as “major diameter direction”) extends substantially parallel to a direction of the groove width of the groove cam  133 . When the second link  220  is in the standby position, a direction of the minor diameter of the pin  228  (hereinafter also referred to as “minor diameter direction”) extends substantially parallel to the direction parallel to the groove width of the groove cam  133 . 
     The first cam  131  formed in the first link  110  is configured to be engaged with the pin  228  of the second link  220  with a clearance therebetween (see  FIGS. 4A and 4B ). Here, “engaged with a clearance” denotes that there is a sufficient gap between the pin  228  and the first cam  131  to maintain the second link  220  stationary even when the first link  110  is pivotally moved by a certain amount (by an amount of the clearance). In other words, there is a little play between the first cam  131  and the pin  228 . 
     The movable member  150  will be described next. The movable member  150  is a plate-like member having a rectangular shape extending in the front-rear direction as viewed in a side view. The movable member  150  is supported by support shafts  161  and  162  protruding leftward from the right plate  280  and is movable in the front-rear direction. The movable member  150  is provided with a projection portion  151  protruding leftward. The projection portion  151  is engaged with the slot  229  formed in the second link  220 . Thus, as the second link  220  is pivotally moved about the pivot shaft  281 , the movable member  150  is also moved in the front-rear direction. 
     The movable member  150  has a front end portion that holds the rotary roller  82 . The rotary roller  82  is positioned rightward of the platen holder  12  (see  FIG. 2 ) and is rotatable about an axis extending in the up-down direction. The rotary roller  82  is configured to press the inclined portion of the platen holder  12  urged by the torsion spring. 
     As the movable member  150  is moved frontward, the rotary roller  82  urges the inclined portion leftward while rolling on the inclined portion to cause the platen holder  12  to be pivotally moved toward its pressure position. As the movable member  150  is moved rearward, the rotary roller  82  rolls on the inclined portion, and thus the platen holder  12  is pivotally moved gradually toward the retracted position by an urging force of the torsion spring. In this way, movement of the movable member  150  in the front-rear direction causes the platen holder  12  to be pivotally moved between the pressure position and the retracted position. 
     Next, how the first link  110 , the second link  220 , and the platen holder  12  (see  FIG. 2 ) are moved when the cover  6  is pivotally moved from the closed position to the open position will be described with reference to  FIGS. 4A to 5B . When the cover  6  is in the closed position (see  FIG. 4A ), the first link  110  is at a lower end of a movable range thereof; the second link  220  is in the operation position; the movable member  150  is at a front end of a movable range thereof; and the platen holder  12  is in the pressure position (see  FIG. 2 ). At this time, a lower end of the first cam  131  is positioned downward of and spaced apart from the pin  228 . 
     Here, a positional relationship between the first link  110  and the pin  228  when the pin  228  is engaged with the first cam  131  will also be referred to as “first positional relationship”, whereas the positional relationship therebetween when the pin  228  is engaged with the second cam  132  will also be referred to as “second positional relationship”. That is, when the pin  228  is at the first portion of the first link  110  as illustrated in  FIGS. 4A to 4C , the first link  110  and the pin  228  provides the first positional relationship therebetween. Similarly, when the pin  228  is at the second portion of the second link  220  as illustrated in  FIG. 5B , the first link  110  and the pin  228  provides the second positional relationship therebetween. 
     As the user starts to open the cover  6 , the cover  6  is pivotally moved within the first movable range toward the open position (see  FIGS. 4A and 4B ). The cover  6  pulls up the pair of shaft portions  111  of the first link  110 , thereby moving the lower end portion of the first cam  131  upward toward the pin  228 . In this state, the clearance between the first cam  131  and the pin  228  can keep the second link  220  stationary in the operation position. 
     After the first cam  131  is pivotally moved by the amount of the clearance, the lower end portion of the first cam  131  abuts against the pin  228  from the lower side thereof (see  FIG. 4B ). Since the major diameter of the pin  228  is greater than the groove width of the groove cam  133 , the pin  228  is prevented from entering the groove cam  133 . Therefore, the first cam  131  presses the pin  228  upward, whereby the second link  220  is pivotally moved from the operation position to the standby position (see  FIGS. 4B and 4C ). 
     While the second link  220  is pivotally moved, the pin  228  is rotated in the first portion inside the first cam  131 . In other words, a posture of the pin  228  relative to the first cam  131  is changed. Specifically, while the pin  228  is rotated, a state where the major diameter direction of the pin  228  and a longitudinal direction of the groove cam  133  intersects with each other is maintained, but an angle θ (see  FIG. 4B ) defined between the major diameter direction of the pin  228  and the longitudinal direction of the groove cam  133  is changed. 
     At the same time, a pivotal movement of the second link  220  causes the slot  229  to press the projection portion  151  rearward, thereby moving the movable member  150  rearward. Accordingly, the platen holder  12  (see  FIG. 2 ) starts to be pivotally moved from the pressure position to the retracted position due to the urging force of the torsion spring. 
     Then, the second link  220  reaches the standby position (see  FIG. 4C ), the movable member  150  reaches a rear end of the movable range thereof, and the platen holder  12  reaches the retracted position. At this time, the minor diameter direction of the pin  228  is substantially parallel to the groove width direction of the groove cam  133 , and the pin  228  becomes movable into the groove cam  133 . The extension portion  225  of the second link  220  is moved to a position closest to the protruding portion  119  of the first link  110  (see  FIG. 4C ). During the pivotal movement of the cover  6  within the first movable range, the positional relationship between the first link  110  and the pin  228  is maintained in the first positional relationship. 
     After reaching the state illustrated in  FIG. 4C , the cover  6  is moved from the first movable range into the second movable range (see  FIG. 5A ). During the movement within the second movable range, the cover  6  continues to pull the pair of shaft portions  111  upward, and the pin  228  enters the groove cam  133 . The pin  228  is slidingly moved relative to the groove cam  133  without changing its posture (i.e., without changing the angle θ), and thus the second link  220  is maintained in the standby position. Therefore, the movable member  150  remains stationary, and the platen holder  12  is maintained in the retracted position. Here, since the groove cam  133  is curved as described above, the pin  228  can be slidingly moved smoothly relative to the groove cam  133 . That is, the positional relationship between the first link  110  and the pin  228  is changed from the first positional relationship toward the second positional relationship in accordance with the pivotal movement of the cover  6  within the second movable range. 
     Thereafter, the cover  6  reaches the open position (see  FIG. 5B ), and the first link  110  reaches an upper end of the movable range thereof. The pin  228  enters and is positioned within the second cam  132 . At this time, the minor diameter direction of the pin  228  is substantially parallel to the groove width direction of the groove cam  133 . 
     Next, how the first link  110 , the second link  220 , and the platen holder  12  are moved while the cover  6  is pivotally moved from the open position to the closed position will be described with reference to  FIGS. 4A to 5B . When the cover  6  is pivotally moved from the open position to the closed position, the first link  110 , the second link  220 , and the platen holder  12  operate in the order of  FIGS. 5B, 5A, 4C, 4B , and  4 A. In short, when the cover  6  is pivotally moved from the open position to the closed position, the operation performed when the cover  6  is pivotally moved from the closed position to the open position described above is reversed. 
     As the user starts to close the cover  6 , the cover  6  is pivotally moved within the second movable range from the open position toward the closed position as illustrated in  FIGS. 5B and 5A . The first link  110  is pivotally moved downward in interlocking relation to the pivotal movement of the cover  6 . Since the minor diameter direction of the pin  228  is substantially parallel to the groove width direction of the groove cam  133 , the pin  228  is moved relatively from the second cam  132  into the groove cam  133 , and is slidingly moved relative to the groove cam  133  to change the positional relationship between the first link  110  and the pin  228  from the second positional relationship toward the first positional relationship. At this time, the second link  220  remains stationary in the standby position, and the platen holder  12  (see  FIG. 2 ) is maintained in the retracted position. 
     Concurrently with entry of the pin  228  into the first cam  131  (see  FIG. 4C ), the cover  6  is moved from the second movable range into the first movable range. At this time, the protruding portion  119  of the first link  110  moving downward in interlocking relation to the pivotal movement of the cover  6  comes closest to the extension portion  225  and abuts the same from the upper side. More specifically, the protruding portion  119  abuts the extension portion  225  to urge the same immediately before the inner side of the first cam  131  makes contact with the pin  228 . 
     As the extension portion  225  is urged by the protruding portion  119 , the second link  220  starts to be pivotally moved from the standby position toward the operation position. The slot  229  formed in the second link  220  presses the projection portion  151  frontward, whereby the movable member  150  is moved frontward to press the platen holder  12  to be pivotally moved from the standby position toward the pressure position. 
     While the extension portion  225  is moved away from the protruding portion  119  (see  FIG. 4B ), both ends in the major diameter direction of the pin  228  is brought into contact with the first cam  131 . This contact causes the pin  228  to be rotated along with the first cam  131  in accordance with the pivotal movement of the first link  110  to cause the second link  220  to continue to be pivotally moved toward the operation position. At this time, as the pin  228  is in contact with and rotated inside the first cam  131 , the positional relationship between the first link  110  and the pin  228  is maintained in the first positional relationship. 
     Eventually, the pin  228  is rotated so that the major diameter direction of the pin  228  becomes substantially parallel to the groove width direction of the groove cam  133  (see  FIG. 4B ). After the cover  6  and the first link  110  are further pivotally moved to displace the first cam  131  further downward, the cover  6  reaches the closed position (see  FIG. 4A ), the second link  220  reaches the operation position, and the platen holder  12  reaches the pressure position. 
     Next, a printing operation of the printer  1  will be described with reference to  FIGS. 1 and 2 . At the beginning of the printing operation, the tape cassette  60  is being attached to the attachment portion  8 , and the cover  6  is being in the closed position (see  FIG. 4A ). When the conveying motor  33  starts to be driven, the ribbon take-up shaft  95 , the drive shaft  100 , and the platen roller  64  in the printer  1  are rotated. The ribbon drawn out from the ribbon spool and the printing medium  5  drawn out from the tape spool are brought into superposition on each other and pass the portion between the platen roller  64  and the printing head  10 . 
     As the heat generating elements of the printing head  10  generate heat, ink contained in the ink ribbon is transferred onto the printing medium  5 , whereby a character is printed on the printing medium  5 . The used ribbon is taken up by the ribbon take-up spool  68 . The printing medium  5  is nipped at the portion between the tape drive roller  46  and the conveying roller  66  and is conveyed thereby toward the discharge opening  11 . After the driving of the conveying motor  33  is stopped, the cutting mechanism cuts the printing medium  5 . Thus, the user can take out the printing medium  5  discharged through the discharge opening  11 . 
     A method for assembling the first link  110  to both the second link  220  and the cover  6  will be described next with reference to  FIGS. 1, 3 and 6 . As described above, the cover  6  is pivotally movably supported by the pair of pivot portions  71 ; the second link  220  is pivotally movably supported by the pivot shaft  281 ; and the projection portion  151  of the movable member  150  is engaged with the slot  229  formed in the second link  220 . At the time of assembly of the first link  110  to both the second link  220  and the cover  6 , the cover  6  is maintained in the open position; the second link  220  is in the standby position; the movable member  150  is at the rear end of the movable range thereof; and the platen holder  12  is in the retracted position. 
     An operator performing the assembly of the first link  110  places the first link  110  so that the second cam  132  is positioned to the left of the pin  228 , and moves the first link  110  rightward as indicated by an arrow L in  FIG. 6 . Accordingly, the second cam  132  is engaged with the pin  228 , and thus the first link  110  is connected to the second link  220 . The operator then pivotally moves the first link  110  about the pin  228  and causes each of the pair of shaft portions  111  to be fitted into the pivot hole  7 A in the corresponding one of the pair of bearing portions  7 . In the detailed description that will be made below, the term “the pair of” is omitted to facilitate understanding of the sentence. 
     As illustrated in  FIG. 6 , each of the bearing portions  7  is formed with a beveled portion  7 B formed on an inner side thereof. When the operator pivotally moves the first link  110  about the pin  228 , each of the shaft portions  111  is brought into contact with the corresponding one of the beveled portions  7 B. In this state, the operator pushes an upper end portion of the first link  110  toward the bearing portions  7 . As a result, the beveled portions  7 B are pressed outward by the shaft portions  111 , thereby causing the bearing portions  7  to be elastically deformed to expand outward. As the bearing portions  7  expand outward, the shaft portions  111  can be moved from the beveled portions  7 B toward the pivot holes  7 A. When the shaft portions  111  reach the respective pivot holes  7 A, the elastically deformed bearing portions  7  return to their original shape, and the shaft portions  111  can be respectively fitted into the pivot holes  7 A. 
     In this way, by fitting the pair of shaft portions  111  into the corresponding one of the pair of pivot holes  7 A, the first link  110  is brought into connection to the cover  6  and the assembly of the first link  110  is completed. 
     As described above, as the second link  220  is pivotally moved from the operation position to the standby position in accordance with the pivotal movement of the cover  6 , the movable member  150  is moved to cause the platen holder  12  to be pivotally moved from the pressure position to the retracted position. 
     When the cover  6  is pivotally moved within the first movable range toward the open position, the connection member  88  causes the second link  220  to be pivotally moved from the operation position to the standby position in interlocking relation to the pivotal movement of the first link  110  while maintaining the pin  228  that connects the first link  110  and the second link  220  to each other at the first portion of the first link  110  (i.e., the positional relationship between the first link  110  and the pin  228  is maintained at the first positional relationship). 
     Further, when the cover  6  is pivotally moved within the second movable range toward the open position, the connection member  88  causes the pin  228  to be moved relatively from the first portion to the second portion of the first link  110  in accordance with the pivotal movement of the first link  110  (i.e., the positional relationship between the first link  110  and the pin  228  is caused to be changed from the first positional relationship to the second positional relationship), and maintains the second link  220  at the standby position. 
     With the above operation, while the cover  6  is pivotally moved, a disengagement of the pin  228  from the cam portion  130  is prevented and the connection member  88  can continue to connect the first link  110  and the second link  220  to each other, thereby enabling the platen holder  12  to be pivotally moved stably between the pressure position and the retracted position. Consequently, the printer  1  according to the present embodiment can stably change a positional relationship between the platen roller  64  and the printing head  10  in accordance with the movement of the cover  6  which serves an operation member operated by the user. 
     Further, as described above, the platen holder  12  starts to be moved from the pressure position at a timing when the cover  6  starts to open the attachment portion  8 . With this configuration, the platen holder  12  can reach the retracted position promptly. Further, when the cover  6  is pivotally moved within the second movable range, the pivotal movement of the second link  220  is restricted to maintain the second link  220  at the standby position. Accordingly, an amount (i.e., the movable range) by which the first link  110  is pivotally moved can be increased. This configuration leads to an increase of an amount (i.e., the movable range) by which the cover  6  is pivotally moved, thereby allowing the attachment portion  8  to be open widely. As a result, the tape cassette  60  including the printing medium  5  can be easily attached to and detached from the attachment portion  8 . 
     The cover  6  is configured to cover the attachment portion  8  so as to open and close the attachment portion  8  which serves an opening configured to accommodate the printing medium  5  therein. When the cover  6  pivotally moved from the closed position to the open position to open the attachment portion  8 , the platen holder  12  is pivotally moved from the pressure position to the retracted position. Therefore, when the cover  6  is in the open position, the user can easily remove the tape cassette  60  including the printing medium  5  from the attachment portion  8  of the housing  2 . 
     When the cover  6  is pivotally moved within the first movable range toward the open position, the connection member  88  maintains the pin  228  at the first portion (i.e., the first cam  131 ) of the first link  110 , and causes the second link  220  to be pivotally moved from the operation position to the standby position by the rotation of the pin  228 . When the cover  6  is pivotally moved within the second movable range, the second link  220  is positioned such that the major diameter direction of the pin  228  is substantially parallel to the longitudinal direction of the groove cam  133 , and the pin  228  enters and is slidingly moved relative to the groove cam  133 . 
     Since the major diameter direction of the pin  228  and the longitudinal direction of the groove cam  133  intersect with each other (see  FIGS. 4A and 4B ) during the pivotal movement of the cover  6  within the first movable range, the pin  228  is prevented from entering the groove cam  133 . The pin  228  can be moved relatively into the groove cam  133  at a timing when the cover  6  is moved from the first movable range into the second movable range (see  FIGS. 4C and 5A ). Further, when the cover  6  is pivotally moved within the second movable range, the pin  228  is slidingly moved relative to the groove cam  133 , and thus the rotation of the pin  228  is restricted by the groove cam  133 . With this configuration, the connection member  88  can maintain the second link  220  at the standby position with ease. 
     The pin  228  has a substantially oblong cross-section taken along a plane perpendicular to the left-right direction in which the center axis  228 A of the pin  228  extends. This simple shape of the pin  228  allows the printer  1  to simplify the configuration of the connection member  88 . 
     At a timing when the cover  6  is moved from the second movable range into the first movable range, the protruding portion  119  presses the extension portion  225  to cause the second link  220  in the standby position to be pivotally moved toward the operation position (see  FIG. 4C ). That is, when the cover  6  is moved from the second movable range into the first movable range, the protruding portion  119  of the first link  110  presses the extension portion  225  positioned farther from the pivot shaft  281  than the pin  228  is from the pivot shaft  281  which serves as the pivot center of the second link  220 . Accordingly, the second link  220  can start the pivotal movement smoothly from the standby position toward the operation position. 
     The first cam  131  is engaged with the pin  228  with a clearance provided therebetween. When the cover  6  starts to be pivotally moved from the closed position, the first cam  131  formed in the first link  110  is moved by the amount of the clearance and then contacts to move the pin  228  upward. In other words, while the first cam  131  of the first link  110  is moved by the amount of the clearance, the pivotal movement of the second link  220  is prevented, and the movement of the movable member  150  is also prevented. This configuration can reduce an operation load applied when the user starts to open the cover  6 . Accordingly, a force needed when the user starts to open the cover  6  can be reduced, whereby the user can easily open the cover  6 . 
     The cam portion  130  includes the second cam  132 . When the printer  1  is assembled together (i.e., when the first link  110  is assemble to the second link  220  and the cover  6 ), the pin  228  of the second link  220  is first engaged with the second cam  132  to allow the second link  220  and the first link  110  to be connected to each other. Accordingly, the assembly of the printer  1  can be facilitated. 
     While the description has been made in detail with reference to the embodiment, it would be apparent to those skilled in the art that various changes and modifications may be made thereto. 
     For example, while the cam portion  130  is in a form of a hole in the above-described embodiment, the cam portion  130  may be a cam surface formed at an outer peripheral edge surface of the first link  110 . In this case, the second link  220  may be urged by an elastic member so that the pin  228  is pressed against the cam surface. Further, the groove cam  133  may have a linear shape instead of a curved shape. 
     The cover  6  is provided at the housing  2  so as to be pivotally movable relative to the housing  2 . However, the cover  6  may be provided at the housing  2  so as to be slidably movable relative to the housing  2 . Further, instead of the cover  6 , the printer  1  may include a lever. The lever need not be capable of opening and closing an opening (i.e., the attachment portion  8 ) provided in the housing  2  as long as the lever is an operation member that is movable in response to the user&#39;s operation. While the first cam  131  and the pin  228  are engaged with each other with a clearance therebetween in the above-described embodiment, such the clearance may not be provided between the first cam  131  and the pin  228 . 
     Further, in the above-described embodiment, the pin  228  provided on the second link  220  has a substantially oblong cross-section taken along a plane perpendicular to the left-right direction. Instead of the above shape, the pin  228  may have an arbitrary cross-section such as a substantially oval cross-section, a substantially ellipse cross-section, a substantially rectangular cross-section, or a substantially polygonal cross-section, as long as the cross-section of the pin  228  has a major diameter and a minor diameter substantially the same as those of the pin  228  described above. 
       FIG. 7  illustrates a modification to the embodiment in which the shape of the pin is different from that in the above-described embodiment. In this modification, a second link  320  that includes a set of pins  248  consisting of two pins  249  is provided instead of the second link  220 . That is, the pin  228  is not provided on the second link  320 . Each of the two pins  249  has a circular columnar shape. 
     The two pins  249  form an imaginary elongated circle  250 . The elongated circle  250  has a major diameter (a dimension T 1 ) smaller than the inner diameter of the first cam  131  and greater than the groove width of the groove cam  133 , and a minor diameter (a dimension T 2 ) smaller than the groove width of the groove cam  133 . Even with the above configuration, the set of pins  248  is prevented from entering the groove cam  133  when the second link  320  is in the operation position (see  FIG. 7 ), and the set of pins  248  is allowed to be moved into the groove cam  133  when the second link  320  is in the standby position (see  FIG. 4C ). 
     Further, the cam portion  130  formed in the first link  110  may not include the second cam  132 . In this case, the cam portion  130  has a shape in which the groove cam  133  is extended to replace the second cam  132 . 
     However, with the above configuration in which the second cam  132  is dispensed with, the first link cannot be assembled in accordance with the method described above. In order to assemble the first link to both the second link  220  and the cover  6  in a different method, the first link includes a through-hole instead of the pair of shaft portions  111 . The through-hole has a diameter equal to a diameter of each pivot hole  7 A. Hereinafter, the first link without the second cam  132  and formed with the through-hole is referred to as “specific first link”. A shaft to be inserted into the through-hole and the pivot holes  7 A is needed separately. The shaft has a length greater than a distance in the left-right direction between the pair of bearing portions  7 . 
     A method of assembly of the specific first link will be described. The operator places the specific first link to the left of the pin  228 . Then, the operator moves the specific first link rightward and causes the pin  228  to be engaged with the groove cam  133  at a position close to a distal end of the groove cam  133 . Thereafter, the operator moves the specific first link to a position where the through-hole formed in the specific first link is aligned with the pivot holes  7 A in the left-right direction. With the positions of the through-hole and the pivot holes  7 A aligned with each other, the shaft is inserted into the through-hole and the pivot holes  7 A. Thereafter, a retaining ring is fixed to each of ends of the shaft protruding outward of the bearing portions  7 , and the assembly of the specific first link is completed.