Patent Publication Number: US-2020298603-A1

Title: Ribbon transport mechanism and tape printing apparatus

Description:
The present application is based on, and claims priority from JP Application Serial Number 2019-051757, filed Mar. 19, 2019, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     This application relates to a ribbon transport mechanism that transports an ink ribbon and a tape printing apparatus equipped with the ribbon transport mechanism. 
     2. Related Art 
     JP-A-2013-159409 discloses a tape printing apparatus equipped with a ribbon transport mechanism that transports an ink ribbon. This ribbon transport mechanism includes a paying-out-side clutch mechanism and a winding-side clutch mechanism. The paying-out-side clutch mechanism selectively transmits the rotational power generated by a drive motor to a paying-out-side drive shaft, whereas the winding-side clutch mechanism selectively transmits the rotational power to a winding-side drive shaft. 
     In a known ribbon transport mechanism as described above, the paying-out-side clutch mechanism includes a paying-out-side sun gear and a paying-out-side planet gear; the paying-out-side planet gear engages with or is disengaged from a paying-out-side input gear while rotating and moving around the paying-out-side sun gear. Likewise, the winding-side clutch mechanism includes a winding-side sun gear and a winding-side planet gear; the winding-side planet gear engages with or is disengaged from a winding-side input gear while rotating and moving around the winding-side sun gear. Such ribbon transport mechanisms and tape printing apparatuses may disadvantageously have large bodies. 
     SUMMARY 
     The disclosed embodiment is a ribbon transport mechanism provided in a tape printing apparatus. This ribbon transport mechanism includes a paying out rotor and a winding rotor. When a cartridge that includes a paying out core around which an ink ribbon is wound and a winding core that winds the ink ribbon paid out from the paying out core is attached to a cartridge mount section of the tape printing apparatus, the paying out rotor engages with the paying out core and the winding rotor engages with the winding core. The ribbon transport mechanism further includes: a transport motor that generates rotational power; and a transport gear train that receives the rotational power from the transport motor and transmits the received rotational power to both the paying out rotor and the winding rotor. The transport gear train includes a paying-out-side one-way clutch and a winding-side one-way clutch. When the transport motor rotates in a first direction, the paying-out-side one-way clutch suppresses the rotational power received from the transport motor from being transmitted to the paying out rotor, whereas when the transport motor rotates in a second direction, the paying-out-side one-way clutch permits the rotational power received from the transport motor to be transmitted to the paying out rotor; the second direction is opposite to the first direction. When the transport motor rotates in the first direction, the winding-side one-way clutch permits the rotational power received from the transport motor to be transmitted to the winding rotor, whereas when the transport motor rotates in the second direction, the winding-side one-way clutch suppresses the rotational power received from the transport motor from being transmitted to the winding rotor. The paying-out-side one-way clutch is coaxial with the winding-side one-way clutch. 
     The present disclosure is a tape printing apparatus to which a cartridge that includes a paying out core around which an ink ribbon is wound and a winding core that winds the ink ribbon paid out from the paying out core is to be attached. This tape printing apparatus includes: a cartridge mount section to which the cartridge is to be attached; a paying out rotor that, when the cartridge is attached to the cartridge mount section, engages with the paying out core; a winding rotor that, when the cartridge is attached to the cartridge mount section, engages with the winding core; a transport motor that generates rotational power; a transport gear train that receives the rotational power from the transport motor and transmits the received rotational power to both the paying out rotor and the winding rotor; and a printing head that performs a printing operation on a print tape. The transport gear train includes a paying-out-side one-way clutch and a winding-side one-way clutch. When the transport motor rotates in a first direction, the paying-out-side one-way clutch suppresses the rotational power received from the transport motor from being transmitted to the paying out rotor, whereas when the transport motor rotates in a second direction, the paying-out-side one-way clutch permits the rotational power received from the transport motor to be transmitted to the paying out rotor; the second direction is opposite to the first direction. When the transport motor rotates in the first direction, the winding-side one-way clutch permits the rotational power received from the transport motor to be transmitted to the winding rotor, whereas when the transport motor rotates in the second direction, the winding-side one-way clutch suppresses the rotational power received from the transport motor from being transmitted to the winding rotor. The paying-out-side one-way clutch is coaxial with the winding-side one-way clutch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a tape printing apparatus in which a tape cartridge is attached to a cartridge mount section, as viewed from an attachment direction. 
         FIG. 2  illustrates the tape printing apparatus in which a ribbon cartridge is attached to the cartridge mount section, as viewed from the attachment direction. 
         FIG. 3  illustrates the tape printing apparatus in which neither the tape cartridge nor the ribbon cartridge is attached to the cartridge mount section, as viewed from the attachment direction. 
         FIG. 4  illustrates, in perspective, the tape printing apparatus in which neither the tape cartridge nor the ribbon cartridge is attached to the cartridge mount section. 
         FIG. 5  illustrates the transport gear train in perspective. 
         FIG. 6  illustrates the transport gear train as viewed from the attachment direction; the directions in which the individual gears and rotors in the transport gear train rotate in conjunction with the rotation of the transport motor in a first direction are denoted by the arrows. 
         FIG. 7  illustrates the transport gear train as viewed from the attachment direction; the directions in which the individual gears and rotors in the transport gear train rotate in conjunction with the rotation of the transport motor in a second direction are denoted by the arrows. 
         FIG. 8  is an exploded, perspective view of the one-way clutch unit. 
         FIG. 9  is an exploded, perspective view of the one-way clutch unit from which the brake member is removed. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     With reference to the accompanying drawings, a description will be given below of a tape printing apparatus  1  according to some embodiments of the present disclosure. These drawings employ an X-Y-Z orthogonal coordinate system, but it should be noted that this coordinate system is used for the sake of the explanation and thus not intended to limit embodiments that will be described below. Furthermore, the number and numeric values of individual components are examples and thus not intended to limit the embodiments. 
     Outline of Tape Printing Apparatus, Tape Cartridge, and Ribbon Cartridge 
     Referring to  FIGS. 1 to 3 , the tape printing apparatus  1  includes a cartridge mount section  2  to which a tape cartridge  101  and a ribbon cartridge  201  are to be selectively attached. In addition, the tape printing apparatus  1  further includes an unillustrated mount section cover that covers or exposes the cartridge mount section  2 . 
     As illustrated in  FIG. 1 , the tape cartridge  101  includes a tape core  102 , a first platen roller  103 , a first paying out core  104 , a first winding core  105 , and a first cartridge case  106 . Wound around the tape core  102  is a first print tape  107 , which is to be paid out from the tape core  102  to the outside of the first cartridge case  106  via a tape outlet  108 . The tape outlet  108  is disposed on the −X-side surface of the outer wall of the first cartridge case  106 . Wound around the first paying out core  104  is a first ink ribbon  109 , which is to be paid out from the first paying out core  104  to the first winding core  105  and wound around the first winding core  105 . The first cartridge case  106 , which forms the exterior of the tape cartridge  101 , contains the tape core  102 , the first platen roller  103 , the first paying out core  104 , the first winding core  105 , the first print tape  107 , and the first ink ribbon  109 . The first cartridge case  106  has a first head insertion hole  111  that penetrates the first cartridge case  106  along the Z axis. 
     As illustrated in  FIG. 2 , the ribbon cartridge  201  includes a second platen roller  203 , a second paying out core  204 , a second winding core  205 , and a second cartridge case  206 . Wound around the second paying out core  204  is a second ink ribbon  209 , which is to be paid out from the second paying out core  204  to the second winding core  205  and wound around the second winding core  205 . The second cartridge case  206 , which forms the exterior of the ribbon cartridge  201 , contains the second platen roller  203 , the second paying out core  204 , the second winding core  205 , and the second ink ribbon  209 . The second cartridge case  206  has a second head insertion hole  211  that penetrates the second cartridge case  206 . The second cartridge case  206  is provided with a second tape route  212 . Furthermore, an unillustrated tape roller around which a second print tape is wound is disposed outside the tape printing apparatus  1  and introduces the second print tape to the second tape route  212 . 
     The second print tape around the tape roller and the second ink ribbon  209  contained in the ribbon cartridge  201  may have any given initial lengths. In this embodiment, the second print tape may be greater in initial length than the first print tape  107  contained in the tape cartridge  101 . Likewise, the second ink ribbon  209  may be greater in initial length than the first ink ribbon  109  contained in the tape cartridge  101 . For example, if the tape printing apparatus  1  prints many labels at one time, the ribbon cartridge  201  is typically attached to the cartridge mount section  2 . 
     As illustrated in  FIGS. 3 and 4 , the cartridge mount section  2  has a recess that is open toward the +Z-side, and a head section  4  and a core projection  5  are disposed on a mount bottom surface  3  of this recess while protruding in the direction opposite to the attachment direction of the cartridge mount section  2 . The head section  4  includes a printing head  6  and a head cover  7  that covers at least +X-, −Y-, and +Z-side surfaces of the printing head  6 . In one embodiment, the printing head  6  may be a thermal head with a heater element. When the tape cartridge  101  is attached to the cartridge mount section  2 , the head cover  7  is inserted into the first head insertion hole  111  and guides the attaching of the tape cartridge  101 . Likewise, when the ribbon cartridge  201  is attached to the cartridge mount section  2 , the head cover  7  is inserted into the second head insertion hole  211  and guides the attaching of the ribbon cartridge  201 . In addition, when the tape cartridge  101  is attached to the cartridge mount section  2 , the core projection  5  is accommodated in an unillustrated core recess provided in the tape cartridge  101 . 
     Disposed on the mount bottom surface  3  are a platen shaft  8 , a first winding shaft  11 , a first paying out shaft  9 , a second paying out shaft  12 , and a second winding shaft  13  so as to be arranged in this order from the −X-side to the +X-side while protruding toward the +Z-side. 
     The platen shaft  8  is disposed close to the +Y-side surface of the printing head  6  while protruding in the direction opposite to the attachment direction. The protrusion of the platen shaft  8  is greater in amount than any of the first paying out shaft  9 , the first winding shaft  11 , the second paying out shaft  12 , and the second winding shaft  13 . When the tape cartridge  101  is attached to the cartridge mount section  2 , the platen shaft  8  is inserted into the first platen roller  103  and guides the attaching of the tape cartridge  101  together with the head cover  7 . Likewise, when the ribbon cartridge  201  is attached to the cartridge mount section  2 , the platen shaft  8  is inserted into the second platen roller  203  and guides the attaching of the ribbon cartridge  201  together with the head cover  7 . Hereinafter, the direction in which the tape cartridge  101  or the ribbon cartridge  201  is attached is referred to as the attachment direction. The attachment direction is parallel to the direction in which the platen shaft  8  protrudes or the Z axis. In this case, the attachment direction corresponds to the direction toward the −Z-side, whereas the direction opposite to the attachment direction corresponds to the direction toward the +Z-side. 
     The platen shaft  8  rotatably supports a platen rotor  14  (see  FIG. 6 ); the first paying out shaft  9  rotatably supports a first paying out rotor  15 ; the first winding shaft  11  rotatably supports a first winding rotor  16 ; the second paying out shaft  12  rotatably supports a second paying out rotor  17 ; and the second winding shaft  13  rotatably supports a second winding rotor  18 . When the tape cartridge  101  is attached to the cartridge mount section  2 , the platen rotor  14  is inserted into and engages with the first platen roller  103 , the first paying out rotor  15  is inserted into and engages with the first paying out core  104 , and the first winding rotor  16  is inserted into and engages with the first winding core  105 . Likewise, when the ribbon cartridge  201  is attached to the cartridge mount section  2 , the platen rotor  14  is inserted into and engages with the second platen roller  203 , the second paying out rotor  17  is inserted into and engages with the second paying out core  204 , and the second winding rotor  18  is inserted into and engages with the second winding core  205 . Each of the platen rotor  14 , the first paying out rotor  15 , the first winding rotor  16 , the second paying out rotor  17 , and the second winding rotor  18  receives the rotational power from a transport motor  20  via a transport gear train  19 . Herein, the mechanism constituted by at least the first paying out rotor  15 , the first winding rotor  16 , the second paying out rotor  17 , the second winding rotor  18 , the transport gear train  19 , and the transport motor  20  corresponds to an example of a “ribbon transport mechanism”. 
     Transport Gear Train 
     Referring to  FIGS. 5 to 7 , the tape printing apparatus  1  further includes a transport gear train  19 . The transport gear train  19  includes a motor-side gear train  21 , a platen-side gear train  22 , a ribbon-side gear train  23 , a one-way clutch unit  24 , a paying-out-side gear train  25 , a first winding-side gear train  26 , and a second winding-side gear train  27 . 
     The motor-side gear train  21  transmits the rotational power generated by the transport motor  20  to both the platen-side gear train  22  and the ribbon-side gear train  23 . The motor-side gear train  21  includes: a first motor-side gear  28  disposed on the output shaft of the transport motor  20 ; a second motor-side gear  29  that engages with the first motor-side gear  28 ; and a third motor-side gear  31  fixed to the back surface of the second motor-side gear  29  as viewed from the attachment direction. The motor-side gear train  21  further includes: a fourth motor-side gear  32  that engages with the third motor-side gear  31 ; and a fifth motor-side gear  33  fixed to the back surface of the fourth motor-side gear  32  as viewed from the attachment direction. 
     When receiving the rotational power from the transport motor  20  via the motor-side gear train  21 , the platen-side gear train  22  transmits the received rotational power to the platen rotor  14 . The platen-side gear train  22  includes: a first platen-side gear  34  that engages with the fifth motor-side gear  33 ; a second platen-side gear  35  fixed to the front surface of the first platen-side gear  34  as viewed from the attachment direction; and a third platen-side gear  36  that engages with the second platen-side gear  35 . The third platen-side gear  36  is rotatably disposed on the platen shaft  8 . The platen rotor  14  is fixed to the front surface of the third platen-side gear  36  as viewed from the attachment direction. 
     When receiving the rotational power from the transport motor  20  via the motor-side gear train  21 , the ribbon-side gear train  23  transmits the received rotational power to the one-way clutch unit  24 . The ribbon-side gear train  23  includes: a first ribbon-side gear  37  that engages with the fourth motor-side gear  32 ; and a second ribbon-side gear  38  fixed to the front surface of the first ribbon-side gear  37  as viewed from the attachment direction. 
     When receiving the rotational power from the transport motor  20  via the second ribbon-side gear  38 , the one-way clutch unit  24  selectively transmits the received rotational power to one or more of the paying-out-side gear train  25 , the first winding-side gear train  26 , and the second winding-side gear train  27 , depending on in which direction the transport motor  20  rotates. More specifically, when the transport motor  20  rotates in a first direction, namely, in a clockwise direction as illustrated in  FIG. 6 , the one-way clutch unit  24  receives the rotational power from the transport motor  20  and transmits the received rotational power to both the first winding-side gear train  26  and the second winding-side gear train  27 . When the transport motor  20  rotates in a second direction, which is opposite to the first direction, namely, in a counterclockwise direction as illustrated in  FIG. 7 , the one-way clutch unit  24  receives the rotational power from the transport motor  20  and transmits the received rotational power to the paying-out-side gear train  25 . Herein, the clockwise and counterclockwise directions correspond to those as viewed from the attachment direction. Details of the configuration of the one-way clutch unit  24  will be described later. 
     When receiving the rotational power from the transport motor  20  via the one-way clutch unit  24 , the paying-out-side gear train  25  transmits the received rotational power to both the first paying out rotor  15  and the second paying out rotor  17 . The paying-out-side gear train  25  includes a first paying-out-side gear  41  and a second paying-out-side gear  42 ; the first paying-out-side gear  41  engages with the paying-out-side one-way clutch  55  that will be described later, and the second paying-out-side gear  42  is disposed in front of the first paying-out-side gear  41  as viewed from the attachment direction and engages with the first-paying-outside gear  41 . The paying-out-side gear train  25  further includes a third paying-out-side gear  43  and a fourth paying-out-side gear  44 ; the third paying-out-side gear  43  is positioned on the −X-side of the second paying-out-side gear  42  and engages with the second paying-out-side gear  42 , and the fourth paying-out-side gear  44  is positioned on the +X-side of the second paying-out-side gear  42  and engages with the second paying-out-side gear  42 . The third paying-out-side gear  43  is coupled to the first paying out rotor  15  so as to be rotatable around the first paying out shaft  9 . The fourth paying-out-side gear  44  is coupled to the second paying out rotor  17  so as to be rotatable around the second paying out shaft  12 . 
     When receiving the rotational power from the transport motor  20  via the one-way clutch unit  24 , the first winding-side gear train  26  transmits the received rotational power to the first winding rotor  16 . The first winding-side gear train  26  includes a first first-winding-side gear  45 , a second first-winding-side gear  46 , and a third first-winding-side gear  47 . The first first-winding-side gear  45  engages with a winding-side one-way clutch  56  that will be described later; the second first-winding-side gear  46  engages with the first first-winding-side gear  45 ; and the third first-winding-side gear  47  engages with the second first-winding-side gear  46 . The third first-winding-side gear  47  is rotatably disposed on the first winding shaft  11  and is coupled to the first winding rotor  16 . 
     When receiving the rotational power from the transport motor  20  via the one-way clutch unit  24 , the second winding-side gear train  27  transmits the received rotational power to the second winding rotor  18 . The second winding-side gear train  27  includes a first second-winding-side gear  48 , a second second-winding-side gear  49 , and a third second-winding-side gear  51 . The first second-winding-side gear  48  engages with the winding-side one-way clutch  56  that will be described later; the second second-winding-side gear  49  engages with the first second-winding-side gear  48 ; and the third second-winding-side gear  51  engages with the second second-winding-side gear  49 . The third second-winding-side gear  51  is rotatably disposed on the second winding shaft  13  and is coupled to the second winding rotor  18 . 
     When the transport motor  20  rotates in the first direction as illustrated in  FIG. 6 , the individual gears constituting the transport gear train  19  rotate in respective directions, which are referred to as first directions of the individual gears. When the transport motor  20  rotates in the second direction as illustrated in  FIG. 7 , the individual gears constituting the transport gear train  19  rotate in respective opposite directions, which are referred to as second directions of the individual gears. For example, the first direction of a drive gear  53 , described later, in the one-way clutch unit  24  corresponds to a clockwise direction, whereas the second direction of the drive gear  53  corresponds to a counterclockwise direction. 
     Printing Process Performed with Tape Cartridge Attached 
     When the tape cartridge  101  is attached to the cartridge mount section  2  of the tape printing apparatus  1  as illustrated in  FIG. 1 , the first platen roller  103  in the tape cartridge  101  engages with the platen rotor  14  in the cartridge mount section  2 , the first paying out core  104  in the tape cartridge  101  engages with the first paying out rotor  15  in the cartridge mount section  2 , and the first winding core  105  in the tape cartridge  101  engages with the first winding rotor  16  in the cartridge mount section  2 . As a result, the transport motor  20  can transmit its rotational power to the first platen roller  103 , the first paying out core  104 , and the first winding core  105 . 
     In addition to the above, the head section  4  in the cartridge mount section  2  is inserted into the first head insertion hole  111  in the tape cartridge  101 . Then, the mount section cover is attached to the cartridge mount section  2 , after which a head moving mechanism  52  (see  FIG. 5 ) moves the printing head  6  to the platen shaft  8 , thereby nipping both the first print tape  107  and the first ink ribbon  109  between the printing head  6  and the first platen roller  103 . 
     Following the above, when the transport motor  20  rotates in the first direction, the rotational power generated by the transport motor  20  is transmitted to both the platen rotor  14  and the first winding rotor  16  via the transport gear train  19 . As a result, the first platen roller  103  rotates in a feeding direction, and the first winding core  105  rotates in a winding direction. Herein, the expression “the first platen roller  103  rotates in a feeding direction” means that the first platen roller  103  rotates in such a way that the first print tape  107  is paid out to the tape outlet  108  and that the first ink ribbon  109  is paid out from the first paying out core  104  to the first winding core  105 . The expression “the first winding core  105  rotates in a winding direction” means that the first winding core  105  rotates in such a way that the first ink ribbon  109  paid out from the first paying out core  104  is wound around the first winding core  105 . 
     When the transport motor  20  rotates in the second direction, the rotational power generated by the transport motor  20  is transmitted to both the platen rotor  14  and the first paying out rotor  15  via the transport gear train  19 . As a result, the first platen roller  103  rotates in a reverse direction, and the first paying out core  104  rotates in a rewinding direction. Herein, the expression “the first platen roller  103  rotates in a reverse direction” means that the first print tape  107  is fed back from the tape outlet  108  to the first print tape  107  and that the first ink ribbon  109  is fed back from the first winding core  105  to the first paying out core  104 . The expression “the first paying out core  104  rotates in a rewinding direction” means that the first ink ribbon  109  paid out from the first paying out core  104  is rewound around the first paying out core  104 . 
     The tape printing apparatus  1  rotates the transport motor  20  in the first direction and heats the printing head  6 . Then, the tape printing apparatus  1  prints information that has been received via an input device, such as a keyboard, on a predetermined portion of the first print tape  107  while feeding both the first print tape  107  and the first ink ribbon  109 . After having printed the information, the tape printing apparatus  1  uses an unillustrated cutter disposed between the cartridge mount section  2  and a tape ejection hole to cut the portion off the first print tape  107 . Then, the tape printing apparatus  1  rotates the transport motor  20  in the second direction, thereby feeding back the first print tape  107  until its end is positioned close to a predetermined site between the printing head  6  and the first platen roller  103 . In this way, the tape printing apparatus  1  successfully minimizes a margin of the first print tape  107  at its forward end which is to be used for the next printing. 
     The tape printing apparatus  1  also performs the printing operation in the same manner when the ribbon cartridge  201  is attached to the cartridge mount section  2 . In short, the tape printing apparatus  1  prints information on the second print tape while feeding both the second print tape and the second ink ribbon  209  between the printing head  6  and the second platen roller  203 . 
     One-Way Clutch Unit 
     As illustrated in  FIG. 8 , the one-way clutch unit  24  includes the drive gear  53 , a clutch shaft  54 , the paying-out-side one-way clutch  55 , the winding-side one-way clutch  56 , and a brake member  57 . 
     The drive gear  53  engages with the second ribbon-side gear  38  (see  FIG. 6 ). Thus, via the second ribbon-side gear  38 , the drive gear  53  receives the rotational power from the transport motor  20 . 
     The clutch shaft  54  rotates together with the drive gear  53 , thereby transmitting the rotational power from the drive gear  53  to both the paying-out-side one-way clutch  55  and the winding-side one-way clutch  56 . The clutch shaft  54  is rotatably supported on a device frame  59  (see  FIG. 6 ) while protruding from a device frame  59  in the direction opposite to the attachment direction. As illustrated in  FIG. 9 , the clutch shaft  54  includes a gear fitting section  61  and a one-way-clutch fitting section  62 ; the gear fitting section  61  is disposed in front of the one-way-clutch fitting section  62  as viewed from the attachment direction. The gear fitting section  61 , which is processed such that its cross section becomes similar to the shape of the letter “D”, is fitted into the drive gear  53 . The one-way-clutch fitting section  62 , which has a circular cross section, is fitted into the winding-side one-way clutch  56  and the paying-out-side one-way clutch  55  in this order. The paying-out-side one-way clutch  55  is coaxial with the winding-side one-way clutch  56 . The clutch shaft  54  has bearings  63  at both the ends. 
     The paying-out-side one-way clutch  55  includes a paying-out-side inner ring member  64  and a paying-out-side outer ring member  65 ; the paying-out-side outer ring member  65  is disposed on the outer circumference of the paying-out-side inner ring member  64 . The clutch shaft  54  is fitted into the paying-out-side inner ring member  64  so that the paying-out-side inner ring member  64  rotates together with the clutch shaft  54 . The paying-out-side inner ring member  64  has, on its outer circumference, three paying-out-side inner ring engaging sections  66  arranged at substantially equal intervals. The paying-out-side outer ring member  65  includes a paying-out-side outer ring gear  67  and a paying-out-side outer ring projection  68 . The paying-out-side outer ring gear  67  is disposed on the outer circumference of the paying-out-side outer ring member  65  and engages with the first paying-out-side gear  41 . The paying-out-side outer ring gear  67  has, on its inner circumference, three unillustrated paying-out-side outer engaging sections arranged at substantially equal intervals. The paying-out-side outer ring projection  68  protrudes in a substantially cylindrical shape and in the direction opposite to the attachment direction from the front surface of the paying-out-side outer ring gear  67  as viewed from the attachment direction. 
     When both the drive gear  53  and the paying-out-side inner ring member  64  rotate in the first direction, the paying-out-side inner ring engaging sections  66  are disengaged from the paying-out-side outer engaging sections. In this case, the torque of the paying-out-side inner ring member  64  is suppressed from being transmitted to the paying-out-side outer ring member  65 . As a result, the paying-out-side outer ring member  65  does not rotate, and the paying-out-side inner ring member  64  thus rotates at idle. When both the drive gear  53  and the paying-out-side inner ring member  64  rotate in the second direction, the paying-out-side inner ring engaging sections  66  engages with the paying-out-side outer engaging sections. In this case, the torque of the paying-out-side inner ring member  64  is permitted to be transmitted to the paying-out-side outer ring member  65 . As a result, the paying-out-side outer ring member  65  rotates in the second direction. In short, when the transport motor  20  rotates in the first direction as illustrated in  FIG. 6 , the paying-out-side one-way clutch  55  receives the rotational power from transport motor  20  via the drive gear  53  and suppresses the received rotational power from being transmitted to the paying-out-side gear train  25 . When the transport motor  20  rotates in the second direction as illustrated in  FIG. 7 , the paying-out-side one-way clutch  55  receives the rotational power from transport motor  20  via the drive gear  53  and permits the received rotational power to be transmitted to the paying-out-side gear train  25 . 
     The winding-side one-way clutch  56  includes a winding-side inner ring member  71  and a winding-side outer ring member  72 ; the winding-side outer ring member  72  is disposed on the outer circumference of the winding-side inner ring member  71 . The clutch shaft  54  is fitted into the winding-side inner ring member  71  so that the winding-side inner ring member  71  rotates together with the clutch shaft  54 . The winding-side inner ring member  71  has, on its outer circumference, three winding-side inner ring engaging sections  73  arranged at substantially equal intervals. The winding-side outer ring member  72  includes a winding-side outer ring gear  74  and a winding-side outer ring projection  75 . The winding-side outer ring gear  74  is disposed on the outer circumference of the winding-side outer ring member  72  and engages with both the first first-winding-side gear  45  and the first second-winding-side gear  48 . The winding-side outer ring gear  74  has, on its inner circumference, three winding-side outer ring engaging sections  76  arranged at substantially equal intervals. The winding-side outer ring projection  75  protrudes in a substantially cylindrical shape and in the attachment direction from the back surface of the winding-side outer ring gear  74  as viewed from the attachment direction. 
     When both the drive gear  53  and the winding-side inner ring member  71  rotate in the first direction, the winding-side inner ring engaging sections  73  engage with the winding-side outer ring engaging sections  76 . In this case, the torque of the winding-side inner ring member  71  is permitted to be transmitted to the winding-side outer ring member  72 . As a result, the winding-side outer ring member  72  rotates in the first direction. When both the drive gear  53  and the winding-side inner ring member  71  rotate in the second direction, the winding-side inner ring engaging section  73  is disengaged from the winding-side outer ring engaging sections  76 . In this case, the torque of the winding-side inner ring member  71  is suppressed from being transmitted to the winding-side outer ring member  72 . As a result, the winding-side outer ring member  72  does not rotate, but the winding-side inner ring member  71  rotates at idle. In short, when the transport motor  20  rotates in the first direction as illustrated in  FIG. 6 , the winding-side one-way clutch  56  receives the rotational power from transport motor  20  via the drive gear  53  and permits the received rotational power to be transmitted to both the first winding-side gear train  26  and the second winding-side gear train  27 . When the transport motor  20  rotates in the second direction as illustrated in  FIG. 7 , the winding-side one-way clutch  56  receives the rotational power from transport motor  20  via the drive gear  53  and suppresses the received rotational power from being transmitted to both the first winding-side gear train  26  and the second winding-side gear train  27 . 
     The paying-out-side one-way clutch  55  and the winding-side one-way clutch  56  may be identical types of one-way clutches. In addition, both of the paying-out-side one-way clutch  55  and the winding-side one-way clutch  56  are disposed on the clutch shaft  54  in mutually opposite orientations, so that the drive gear  53  rotates in opposite directions when the torque is transmitted to the paying-out-side one-way clutch  55  and when the torque is transmitted to the winding-side one-way clutch  56 . By using identical types of one-way clutches for the paying-out-side one-way clutch  55  and the winding-side one-way clutch  56 , the number of different types of components can be decreased. Herein, identical types of one-way clutches refer to those that have the same product number and be produced by the same manufacturer. However, the paying-out-side one-way clutch  55  and the winding-side one-way clutch  56  do not necessarily have to be identical types of one-way clutches. 
     The brake member  57  is configured to stop the rotations of the paying-out-side outer ring member  65  and the winding-side outer ring member  72  which are caused by the idle torque. As described above, when the transport motor  20  and the paying-out-side inner ring member  64  in the paying-out-side one-way clutch  55  rotate in the first direction, the paying-out-side inner ring member  64  suppresses the torque from being transmitted to the paying-out-side outer ring member  65 , so that the paying-out-side outer ring member  65  does not rotate and the paying-out-side inner ring member  64  thus rotates at idle. In this case, however, if no load is placed on the paying-out-side outer ring member  65 , the idle torque of the paying-out-side one-way clutch  55  may be transmitted to the paying-out-side outer ring member  65  through the sliding friction generated between the paying-out-side inner ring member  64  and the paying-out-side outer ring member  65 . This idle torque acts on the paying-out-side outer ring member  65  so as to rotate in the first direction. As a result, if the transport motor  20  rotates in the first direction, a backlash may be generated in the first paying-out-side gear  41  at the front end of the paying-out-side one-way clutch  55  in the second direction. 
     If the backlash is generated in the above manner, when the transport motor  20  switches its rotational direction from the first direction to the second direction, both the first paying out rotor  15  and the second paying out rotor  17  may start rotating after the first platen roller  103  or the second platen roller  203  has rotated. In this case, while being fed back to the first paying out core  104 , the first ink ribbon  109  may become loose and fail to be properly wound around the first paying out core  104 , or while being fad back to the second paying out core  204 , the second ink ribbon  209  may become loose and fail to be properly wound around the second paying out core  204 . In this embodiment, the brake member  57  is therefore provided to stop the paying out-side outer ring member  65  from rotating in the first direction due to the idle torque of the paying-out-side one-way clutch  55 , thereby reducing the generation of the backlash in the first paying-out-side gear  41  at the front end of the paying-out-side one-way clutch  55  in the second direction. 
     Likewise the above, if a backlash is generated in both the first first-winding-side gear  45  and the first second-winding-side gear  48  at the front end of the winding-side one-way clutch  56  in the first direction due to the idle torque of the winding-side one-way clutch  56 , when the transport motor  20  switches its rotational direction from the second direction to the first direction, the first winding rotor  16  and the second winding rotor  18  may start rotating after the first platen roller  103  or the second platen roller  203  has rotated. In this embodiment, the brake member  57  is therefore provided to stop the winding-side outer ring member  72  from rotating in the second direction due to the idle torque of the winding-side one-way clutch  56 , thereby reducing the generation of the backlash in both the first first-winding-side gear  45  and the first second-winding-side gear  48  at the front end of the winding-side one-way clutch  56  in the first direction. 
     As illustrated in  FIG. 8 , the brake member  57  includes a coupling section  81 , a fixed section  82 , a paying-out-side brake section  83 , and a winding-side brake section  84 . The coupling section  81 , the fixed section  82 , the paying-out-side brake section  83 , and the winding-side brake section  84  may be integrally formed by bending a single elastic plate, for example, made of metal. 
     The coupling section  81 , which is elongated in the attachment direction, joins the paying-out-side brake section  83  to the winding-side brake section  84 . The fixed section  82  protrudes from the front end of the coupling section  81  in the attachment direction toward the +Y-side and is fixed to the device frame  59 . 
     The paying-out-side brake section  83  stops the paying-out-side outer ring member  65  from rotating due to the idle torque of the paying-out-side one-way clutch  55 . The paying-out-side brake section  83  has two paying-out-side pinching sections  85  that protrude in the −Y direction from +X and −X sides of the coupling section  81 . Provided near the ends of the paying-out-side pinching sections  85  are paying-out-side sliding sections  86  each of which has an arc shape. 
     The paying-out-side pinching sections  85  pinch the circumference of the paying-out-side outer ring projection  68  by using the paying-out-side sliding sections  86  (see  FIG. 6 ). When the paying-out-side outer ring member  65  rotates, a sliding friction is generated between each paying-out-side sliding section  86  and the outer circumference of the paying-out-side outer ring projection  68  to place a sliding load on the paying-out-side outer ring member  65 . This sliding load is effective in stopping the paying-out-side outer ring member  65  from rotating in the first direction due to the idle torque generated when the paying-out-side inner ring member  64  rotates in the first direction, thereby successively reducing generation of a backlash in the first paying-out-side gear  41  at the front end of the paying-out-side one-way clutch  55  in the second direction. The sliding torque may be set to be sufficiently lower than the torque that the paying-out-side inner ring member  64  transmits to the paying-out-side outer ring member  65  when the paying-out-side inner ring member  64  rotates in the second direction. Setting the sliding torque in this manner sufficiently reduces the sliding load that the paying-out-side pinching sections  85  place on the paying-out-side outer ring member  65  when the paying-out-side inner ring member  64  rotates in the second direction, thereby successfully facilitating the rotation of the paying-out-side inner ring member  64 . 
     The ends of the paying-out-side pinching sections  85  are provided with respective paying-out-side pushing sections  87  each of which protrudes from a corresponding one of the paying-out-side pinching sections  85  toward the other. The paying-out-side pushing sections  87  make contact with the front surface of the paying-out-side outer ring projection  68  as viewed from the attachment direction and press the paying-out-side outer ring member  65  so as not to displace in the attachment direction during the rotation. Providing the paying-out-side pushing sections  87  in this manner successfully reduces the risk of the base portions of the paying-out-side pinching sections  85  making contact with the paying-out-side outer ring gear  67  to disturb the rotation of the paying-out-side outer ring member  65 . 
     The winding-side brake section  84  of the brake member  57  is configured to stop the winding-side outer ring member  72  from rotating due to an idle torque of the winding-side one-way clutch  56 . The winding-side brake section  84  may have substantially the same configuration as the paying-out-side brake section  83 . More specifically, the winding-side brake section  84  is provided with two winding-side pinching sections  88  that protrude from the front ends of the coupling section  81  in the attachment direction toward the −Y-side. Provided near the ends of the winding-side pinching sections  88  are respective winding-side sliding sections  89 . When the winding-side inner ring member  71  rotates in the second direction, the winding-side pinching sections  88  place a sliding load on the winding-side outer ring member  72 , thereby stopping the winding-side outer ring member  72  from rotating in the second direction due to the idle torque. This sliding load is effective in reducing generation of a backlash in both the first first-winding-side gear  45  and the first second-winding-side gear  48  at the front end of the winding-side one-way clutch  56  in the first direction. It should be noted that the ends of the winding-side pinching sections  88  are not provided with winding-side pressers, which are equivalent to the paying-out-side pushing sections  87  at the ends of the paying-out-side pinching sections  85 . One reason is that, instead of such winding-side pressers, the device frame  59  makes contact with the back side of the winding-side outer ring projection  75  as viewed from the attachment direction and reduces displacement of the winding-side outer ring member  72  in the attachment direction during the rotation. Obviously, winding-side pressers may be provided in the winding-side pinching sections  88 . 
     The Number of Engagement Points 
     With reference to  FIGS. 6 and 7 , a description will be given below of the number of points at which gears in the transport gear train  19  engage with one another. As described above, when the transport motor  20  rotates in the first direction, the brake member  57  reduces generation of a backlash in the first paying-out-side gear  41  at the front end of the paying-out-side one-way clutch  55  in the second direction. This configuration, when the transport motor  20  rotates in the first direction, reduces generation of backlashes in the output-side gears of the engaging gears at the front ends of the input-side gears in the second direction between the paying-out-side one-way clutch  55  and the first paying out rotor  15  or between the paying-out-side one-way clutch  55  and the second paying out rotor  17 . When the transport motor  20  rotates in the second direction, the brake member  57  reduces generation of a backlash in both the first first-winding-side gear  45  and the first second-winding-side gear  48  at the front end of the winding-side one-way clutch  56  in the first direction. This configuration, when the transport motor  20  rotates in the second direction, reduces generation of backlashes in the output-side gears of the engaging gears at the front ends of the input-side gears in the first direction between the winding-side one-way clutch  56  and the first winding rotor  16  or between the winding-side one-way clutch  56  and the second winding rotor  18 . 
     On the other hand, when the transport motor  20  rotates in the first direction, backlashes are also generated in the output-side gears of the engaging gears at the front ends of the input-side gears in the second direction between the transport motor  20  and the one-way clutch unit  24 . When the transport motor  20  rotates in the second direction, backlashes are also generated in the output-side gears at the front ends of the input-side gears in the first direction therebetween. 
     Likewise the above, when the transport motor  20  rotates in the first direction, backlashes are generated in the output-side gears of the engaging gears at the front ends of the input-side gears in the second direction between the transport motor  20  and the platen rotor  14 . When the transport motor  20  rotates in the second direction, backlashes are also generated in the output-side gears at the front ends of the input-side gears in the first direction therebetween. 
     When the transport motor  20  switches its rotational direction from the first direction to the second direction, backlashes generated in the output-side gears at the front ends of the input-side gears in the second direction are maintained for a period proportional to the number of points at which the gears engage with one another. For example, if the number of points at which the gears engage with one another between the transport motor  20  and the one-way clutch unit  24  is larger than that between the transport motor  20  and the platen rotor  14 , when the transport motor  20  switches its rotational direction from the first direction to the second direction, both the first paying out rotor  15  and the second paying out rotor  17  may start rotating after the platen rotor  14  has started rotating. In this case, while being fed back to the first paying out core  104 , the first ink ribbon  109  may become loose and fail to be properly wound around the first paying out core  104 , or while being fad back to the second paying out core  204 , the second ink ribbon  209  may become loose and fail to be properly wound around the second paying out core  204 . 
     Likewise the above, when the transport motor  20  switches its rotational direction from the second direction to the first direction, backlashes generated in the output-side gears at the front ends of the input-side gears in the second direction are maintained for a period proportional to the number of points at which the gears engage with one another. For example, if the number of engagement points of the gears between the transport motor  20  and the one-way clutch unit  24  is larger than that between the transport motor  20  and the platen rotor  14 , when the transport motor  20  switches its rotational direction from the second direction to the first direction, both the first winding rotor  16  and the second winding rotor  18  may start rotating after the platen rotor  14  has started rotating. In this case, while being paid out to the first winding core  105 , the first ink ribbon  109  may become loose and fail to be properly wound around the first winding core  105 , or while being fad to the second winding core  205 , the second ink ribbon  209  may become loose and fail to be properly wound around the second winding core  205 . 
     To avoid the above disadvantages, the number of points at which the gears engage with one another between the transport motor  20  and the one-way clutch unit  24  is set to be equal to or smaller than that between the transport motor  20  and the platen rotor  14 . The engagement points of the gears between the transport motor  20  and the one-way clutch unit  24  are located between the first motor-side gear  28  and the second motor-side gear  29 , between the third motor-side gear  31  and the fourth motor-side gear  32 , between the fourth motor-side gear  32  and the first ribbon-side gear  37 , and between the second ribbon-side gear  38  and the drive gear  53 . The engagement points of the gears between the transport motor  20  and the platen rotor  14  is located between the first motor-side gear  28  and the second motor-side gear  29 , between the third motor-side gear  31  and the fourth motor-side gear  32 , between the fifth motor-side gear  33  and the first platen-side gear  34 , and between the second platen-side gear  35  and the third platen-side gear  36 . 
     In this embodiment, the number of points at which the gears engage with one another between the transport motor  20  and the one-way clutch unit  24  is set to be equal to that between the transport motor  20  and the platen rotor  14 . This configuration contributes to a shortened time by which the instant when both the first paying out rotor  15  and the second paying out rotor  17  start rotating is delayed from the instant when the platen rotor  14  starts rotating in the case where the transport motor  20  switches its rotational direction from the first direction to the second direction. Also, the configuration contributes to a shortened time by which the instant when both the first winding rotor  16  and the second winding rotor  18  start rotating is delayed from the instant when the platen rotor  14  starts rotating in the case where the transport motor  20  switches its rotational direction from the second direction to the first direction. However, the number of engagement points of the gears between the transport motor  20  and the one-way clutch unit  24  does not necessarily have to be set to be equal to that between the transport motor  20  and the platen rotor  14 . Alternatively, the number of engagement points of the gears between the transport motor  20  and the one-way clutch unit  24  may be set to be smaller than that between the transport motor  20  and the platen rotor  14 . 
     According to a tape printing apparatus  1  in one embodiment, as described above, a paying-out-side one-way clutch  55  is coaxial with a winding-side one-way clutch  56 . The tape printing apparatus  1  thereby can switch between modes in which a first winding rotor  16  and a second winding rotor  18  rotate and in which a first paying out rotor  15  and a second paying out rotor  17  rotate without involving the enlargement of a transport gear train  19 . In which case, a one-way clutch unit  24  does not occupy a large space. 
     According to a tape printing apparatus  1  in another embodiment, a clutch mechanism including a paying-out-side one-way clutch  55  and a winding-side one-way clutch  56  provides a decreased time loss caused when the transport motor  20  switches its rotational direction, as opposed to a clutch mechanism in which a second gear rotates and moves around a first gear and engages or is disengaged from a third gear. This configuration thereby contributes to a shortened time by which the instant when a first paying out rotor  15  and a second paying out rotor  17  start rotating is delayed from the instant when a first platen roller  103  or a second platen roller  203  starts rotating in the case where a transport motor  20  switches its rotational direction from a first direction to a second direction. Also, the configuration contributes to a shortened time by which the instant when a first winding rotor  16  and a second winding rotor  18  start rotating is delayed from the instant when the first platen roller  103  or the second platen roller  203  starts rotating in the case where a transport motor  20  switches its rotational direction from the second direction to the first direction. 
     According to a tape printing apparatus  1  in still another embodiment, a paying-out-side brake section  83  of a brake member  57  reduces generation of a backlash in a first paying-out-side gear  41  at the front end of a paying-out-side one-way clutch  55  in the second direction which is caused by an idle torque of the paying-out-side one-way clutch  55 . This configuration contributes to a shortened time by which the instant when a first paying out rotor  15  and a second paying out rotor  17  start rotating is delayed from the instant when a first platen roller  103  or a second platen roller  203  starts rotating in the case where a transport motor  20  switches its rotational direction from a first direction to a second direction. Likewise, a winding-side brake section  84  of the brake member  57  reduces generation of a backlash in a first first-winding-side gear  45  and a first second-winding-side gear  48  at the front end of a winding-side one-way clutch  56  in the first direction. This configuration contributes to a shortened time by which the instant when a first winding rotor  16  and a second winding rotor  18  start rotating is delayed from the instant when the first platen roller  103  or the second platen roller  203  starts rotating in the case where the transport motor  20  switches its rotational direction from the second direction to the first direction. 
     According to a tape printing apparatus  1  in yet another embodiment, the number of points at which gears engage with one another between a transport motor  20  and a one-way clutch unit  24  is set to be equal to that between the transport motor  20  and a platen rotor  14 . This configuration contributes to a shortened time by which the instant when a first paying out rotor  15  and a second paying out rotor  17  start rotating is delayed from the instant when a first platen roller  103  or a second platen roller  203  starts rotating in the case where a transport motor  20  switches its rotational direction from a first direction to a second direction. Also, the configuration contributes to a shortened time by which the instant when a first winding rotor  16  and a second winding rotor  18  start rotating is delayed from the instant when the first platen roller  103  or the second platen roller  203  starts rotating in the case where the transport motor  20  switches its rotational direction from the second direction to the first direction. 
     Modifications 
     The foregoing embodiment may be modified in various ways without departing from the scope of the present disclosure. Some conceivable modifications will be described below. 
     In the foregoing embodiment, the brake member  57  has the paying-out-side brake section  83  that stops the rotation of the paying-out-side outer ring member  65  by pinching the paying-out-side outer ring projection  68  in a substantially radial direction with the two paying-out-side pinching sections  85 . However, the configuration of stopping the rotation of the paying-out-side outer ring member  65  is not limited. Alternatively, the paying-out-side brake section  83  may stop the rotation of the paying-out-side outer ring member  65  by pinching the paying-out-side outer ring member  65  in a thickness direction with the two-side pinching sections  85 . Likewise, the winding-side brake section  84  may stop the rotation of the winding-side outer ring member  72  by pinching the winding-side outer ring member  72  in a thickness direction with the two winding-side pinching sections  88 . In this case, the brake member  57  may have a common pinching section to pinch the paying-out-side outer ring member  65  and the winding-side outer ring member  72  together in a thickness direction. Alternatively, the brake member  57  may independently pinch the paying-out-side outer ring member  65  and the winding-side outer ring member  72  in a thickness direction. By independently pinching the paying-out-side outer ring member  65  and the winding-side outer ring member  72 , it is possible to reduce the risk of one of the paying-out-side outer ring member  65  and the winding-side outer ring member  72  rotating together with the other by means of the sliding friction. In the foregoing embodiment, the paying-out-side brake section  83  and the winding-side brake section  84  are integrated with each other in the brake member  57 . However, the configuration of the brake member  57  is not limited. Alternatively, the paying-out-side brake section  83  and the winding-side brake section  84  may be formed separately from each other. 
     The cartridge mount section  2  of the tape printing apparatus  1  is not necessarily configured to selectively accommodate the tape cartridge  101  and the ribbon cartridge  201 . As an alternative example, the cartridge mount section  2  may be configured to accommodate only the tape cartridge  101 , in which case the second paying out rotor  17  and the second winding rotor  18  are unnecessary. As another alternative example, the cartridge mount section  2  may be configured to accommodate only the ribbon cartridge  201 , in which case the first paying out rotor  15  and the first winding rotor  16  are unnecessary. Moreover, the present disclosure may be applied to ribbon transport mechanisms without the printing head  6 . 
     A description will be given below of supplementary notes of a ribbon transport mechanism and a tape printing apparatus according to some aspects of the present disclosure. 
     Supplementary Notes 
     A description will be given below of supplementary notes of a ribbon transport mechanism and a tape printing apparatus according to some aspects of the present disclosure. 
     A ribbon transport mechanism provided in a tape printing apparatus includes a paying out rotor and a winding rotor. When a cartridge that includes a paying out core around which an ink ribbon is wound and a winding core that winds the ink ribbon paid out from the paying out core is attached to a cartridge mount section of the tape printing apparatus, the paying out rotor engages with the paying out core and the winding rotor engages with the winding core. The ribbon transport mechanism further includes: a transport motor that generates rotational power; and a transport gear train that receives the rotational power from the transport motor and transmits the received rotational power to both the paying out rotor and the winding rotor. The transport gear train includes a paying-out-side one-way clutch and a winding-side one-way clutch. When the transport motor rotates in a first direction, the paying-out-side one-way clutch suppresses the rotational power received from the transport motor from being transmitted to the paying out rotor, whereas when the transport motor rotates in a second direction, the paying-out-side one-way clutch permits the rotational power received from the transport motor to be transmitted to the paying out rotor; the second direction is opposite to the first direction. When the transport motor rotates in the first direction, the winding-side one-way clutch permits the rotational power received from the transport motor to be transmitted to the winding rotor, whereas when the transport motor rotates in the second direction, the winding-side one-way clutch suppresses the rotational power received from the transport motor from being transmitted to the winding rotor. The paying-out-side one-way clutch is coaxial with the winding-side one-way clutch. 
     The configuration in which the paying-out-side one-way clutch is coaxial with the winding-side one-way clutch contributes to downsizing of the ribbon transport mechanism. 
     In the ribbon transport mechanism, the paying-out-side one-way clutch and the winding-side one-way clutch may be identical types of one-way clutches and disposed in mutually opposite orientations. 
     The above configuration contributes to a decreased number of different types of components. 
     In the ribbon transport mechanism, the transport gear train may include a drive gear that receives the rotational power from the transport motor and a clutch shaft that rotates together with the drive gear. The paying-out-side one-way clutch may include a paying-out-side inner ring member into which the clutch shaft is fitted and a paying-out-side outer ring member disposed on an outer circumference of the paying-out-side inner ring member. The winding-side one-way clutch may include a winding-side inner ring member into which the clutch shaft is fitted and a winding-side outer ring member disposed on an outer circumference of the winding-side inner ring member. 
     The above configuration operates the paying-out-side one-way clutch and the winding-side one-way clutch by using a common drive gear and clutch shaft. In short, the paying-out-side one-way clutch and the winding-side one-way clutch share the common drive gear and the clutch shaft, which contributes to a decreased number of components. 
     In the ribbon transport mechanism, the cartridge may include a platen roller that transports the ink ribbon between the paying out core and the winding core. The ribbon transport mechanism may include a platen rotor that engages with the platen roller when the cartridge is attached to the cartridge mount section. The transport motor may include a paying-out-side brake section that stops the paying-out-side outer ring member from rotating due to an idle torque of the paying-out-side one-way clutch when the transport motor rotates in the first direction. 
     The above configuration contributes to a shortened time by which the instant when the paying out rotor starts rotating is delayed for the instant when the platen roller starts rotating in the case where the transport motor switches its rotational direction from the first direction to the second direction. 
     In the ribbon transport mechanism, the cartridge may include a platen roller that transports the ink ribbon between the paying out core and the winding core. The ribbon transport mechanism may include a platen rotor that engages with the platen roller when the cartridge is attached to the cartridge mount section. The transport motor may include a winding-side brake section that stops the winding-side outer ring member from rotating due to an idle torque of the winding-side one-way clutch when the transport motor rotates in the second direction. 
     The above configuration contributes to a shortened time by which the instant when the winding rotor starts rotating is delayed for the instant when the platen roller starts rotating in the case where the transport motor switches its rotational direction from the second direction to the first direction. 
     In the ribbon transport mechanism, the cartridge may include a platen roller that transports the ink ribbon between the paying out core and the winding core. The ribbon transport mechanism may include a platen rotor that engages with the platen roller when the cartridge is attached to the cartridge mount section. In the transport gear train, a number of points at which gears engage with one another between the transport motor and the paying-out-side one-way clutch or between the transport motor and the winding-side one-way clutch may be equal to or smaller than a number of points at which gears engage with one another between the transport motor and the platen rotor. 
     The above configuration contributes to a shortened time by which the instant when the paying out rotor starts rotating is delayed for the instant when the platen roller starts rotating in the case where the transport motor switches its rotational direction from the first direction to the second direction. Also, the configuration contributes to a shortened time by which the instant when the winding rotor starts rotating is delayed for the instant when the platen roller starts rotating in the case where the transport motor switches its rotational direction from the second direction to the first direction. 
     A tape printing apparatus to which a cartridge that includes a paying out core around which an ink ribbon is wound and a winding core that winds the ink ribbon paid out from the paying out core is to be attached includes: a cartridge mount section to which the cartridge is to be attached; a paying out rotor that, when the cartridge is attached to the cartridge mount section, engages with the paying out core; a winding rotor that, when the cartridge is attached to the cartridge mount section, engages with the winding core; a transport motor that generates rotational power; a transport gear train that receives the rotational power from the transport motor and transmits the received rotational power to both the paying out rotor and the winding rotor; and a printing head that performs a printing operation on a print tape. The transport gear train includes a paying-out-side one-way clutch and a winding-side one-way clutch. When the transport motor rotates in a first direction, the paying-out-side one-way clutch suppresses the rotational power received from the transport motor from being transmitted to the paying out rotor, whereas when the transport motor rotates in a second direction, the paying-out-side one-way clutch permits the rotational power received from the transport motor to be transmitted to the paying out rotor; the second direction is opposite to the first direction. When the transport motor rotates in the first direction, the winding-side one-way clutch permits the rotational power received from the transport motor to be transmitted to the winding rotor, whereas when the transport motor rotates in the second direction, the winding-side one-way clutch suppresses the rotational power received from the transport motor from being transmitted to the winding rotor. The paying-out-side one-way clutch is coaxial with the winding-side one-way clutch. 
     The configuration in which the paying-out-side one-way clutch is coaxial with the winding-side one-way clutch contributes to downsizing of the tape printing apparatus.