JP2018090414A - Printer - Google Patents

Abstract

A printing apparatus capable of accurately specifying the outer diameter of an ink ribbon mounted on a spool is provided. A printing apparatus 1 includes a ribbon mounting portion 2 having a first spool 21 and a second spool 22, a motor, a thermal head 3 provided in a part of a conveyance path R, a thermal head 3 and a first spool 21. The first sensor assembly 4 is provided at any position between the first and second positions, is movable in the first movement direction M1, and can output a signal indicating a first value corresponding to the position in the first movement direction M1, and a thermal head 3 is provided at any position between the second spool 22 and the second spool 22, is movable in the second movement direction M2, and can output a signal indicating a second value corresponding to the position in the second movement direction M2. The two-sensor assembly 5 includes a controller that specifies the tension acting on the ink ribbon 9 and the radius of the first ribbon roll 9A. The control unit specifies the tension and the outer diameter using the first value and the second value. [Selection] Figure 1

Description

  The present invention relates to a printing apparatus.

  Patent Document 1 discloses a printing apparatus that derives the remaining amount of roll paper by the following method. The printing apparatus includes a tension roller installed immediately after a holding unit that holds roll paper. The tension roller moves from the first position to the second position as the amount of roll paper between the holding unit and the winding unit becomes excessive. When the tension roller is in the first position, the printing apparatus starts a rotation operation that rotates the rotation shaft of the holding unit at a predetermined rotation speed. The printing apparatus stops the rotation operation of the rotation shaft of the holding unit when the tension roller is in the second position. The printing apparatus derives the remaining amount (outer diameter) of the roll paper held by the holding unit according to the time for which the tension roller moves from the first position to the second position.

JP 2015-44632 A

  The thermal transfer type printing apparatus heats the ink ribbon with the thermal head while moving the ink ribbon relative to the thermal head to perform printing on the print medium. When the ink ribbon is fed out from the spool on the feeding side and is taken up on the spool on the winding side to move relative to each other, in order to maintain the tension of the ink ribbon in an appropriate state, each spool is set at an appropriate rotation speed. Need to rotate. Note that the appropriate rotation speed of the spool changes according to the outer diameter of the ink ribbon mounted on the spool. Therefore, in order to rotate each spool at an appropriate rotation speed, it is necessary to accurately specify the outer diameter that changes in accordance with the remaining amount of the ink ribbon.

  However, the above method is based on the premise that the spool is continuously rotated at a predetermined rotational speed. On the other hand, the movement speed when the ink ribbon moves relative to the thermal head may be variably controlled. In this case, since it is necessary to change the rotational speed of the spool, the above method has a problem that the outer diameter of the ink ribbon mounted on the spool cannot be specified with high accuracy.

  An object of the present invention is to provide a printing apparatus capable of accurately specifying the outer diameter of an ink ribbon mounted on a spool.

  A printing apparatus according to a first aspect of the present invention includes a first spool and a second spool, and when a ribbon roll is attached to one of the first spool and the second spool, the ribbon roll is changed to an ink ribbon. A ribbon mounting portion that winds the fed ink ribbon around the other of the first spool and the second spool, a motor that rotates at least one of the first spool and the second spool, A thermal head provided in a part of a transport path of the ink ribbon transported between one spool and the second spool, and any of the transport paths between the thermal head and the first spool. A first guide that is movably provided in the first movement direction and is biased toward one side of the first movement direction. The first guide that contacts the ink ribbon when the ink ribbon is attached to the attachment portion and guides the ink ribbon between the thermal head and the first spool; and the first guide of the first guide. A first sensor capable of outputting a signal corresponding to a position in one moving direction and indicating a first value depending on a first outer diameter of the ink ribbon mounted on the first spool; and the transport path A second guide that is movably provided in the second movement direction at any position between the thermal head and the second spool and is biased toward one side of the second movement direction. The second guide for contacting the ink ribbon between the thermal head and the second spool when the ink ribbon is mounted on the ribbon mounting portion; A signal that can output a signal indicating a second value that is a value corresponding to the position of the second guide in the second movement direction and that does not depend on the second outer diameter of the ink ribbon mounted on the second spool. 2 sensors and a control unit that controls the motor based on the first outer diameter, the control unit using the first value and the second value, tension acting on the ink ribbon, And the said 1st outer diameter is specified, It is characterized by the above-mentioned.

  In the printing apparatus according to the first aspect, the first sensor outputs a signal indicating a first value depending on the first outer diameter of the ribbon roll mounted on the first spool. The second sensor outputs a signal indicating a second value that does not depend on the second outer diameter of the ribbon roll mounted on the second spool. A control part specifies the tension | tensile_strength which acts on an ink ribbon, and the 1st outer diameter of the ribbon roll with which the 1st spool was mounted | worn using 1st value and 2nd value. In the above method, the rotational speeds of the first spool and the second spool are not referred to when specifying the tension and the first outer diameter. Therefore, the printing apparatus can accurately specify the first outer diameter of the ribbon roll mounted on the first spool even when the rotational speeds of the first spool and the second spool are variably controlled.

  1st aspect WHEREIN: The 3rd guide provided in the position in any one of the said thermal path and the said 1st guide is further provided in the said conveyance path | route, and the said 3rd guide is the said ribbon mounting part, When the ink ribbon is mounted, the ink ribbon comes into contact with the ink ribbon and guides the ink ribbon from the third guide toward the thermal head in the first transport direction, and the first guide moves the ink ribbon to the ribbon mounting portion. When the ribbon is loaded, the ink ribbon heading from the first guide toward the third guide is guided in the second transport direction, and the third guide is guided with respect to the first spool in the second transport direction. It may be located opposite to. In this case, the angle formed by the direction of the ink ribbon extending between the ribbon roll mounted on the first spool and the first guide and the direction of the ink ribbon extending between the first guide and the third guide is an acute angle. can do. The force acting on the first guide includes a component of a force in the direction of the ink ribbon extending between the ribbon roll and the first guide, and a force in the direction of the ink ribbon extending between the first guide and the third guide. It is expressed by the resultant force with the component. Therefore, the resultant force acting on the first guide can be increased by setting the angles formed by each to an acute angle. In this case, the first guide can easily move in accordance with the tension of the ink ribbon, so the first sensor can accurately detect the tension of the ink ribbon.

  In the first aspect, the first movement direction may be parallel to the second transport direction. That is, the direction in which the first guide can be moved coincides with the transport direction of the ink ribbon. In this case, when the first guide moves according to the tension of the ink ribbon, the movement of the first guide is not hindered by the ink ribbon. Accordingly, since the first guide is easily moved in the first movement direction, the first sensor can detect the tension of the ink ribbon with higher accuracy.

  1st aspect WHEREIN: The 4th guide provided in any position between the said 2nd guide and the said 2nd spool is further provided in the said conveyance path | route, and the said 4th guide is the said ribbon mounting part, When the ink ribbon is attached, the ink ribbon comes into contact with the ink ribbon, guides the ink ribbon from the fourth guide toward the second guide in the third transport direction, and the second guide passes from the second guide to the second guide. The ink ribbon toward the thermal head may be guided in the first transport direction, and may be positioned opposite to the fourth guide with respect to the second spool in the third transport direction. In this case, the angle formed by the direction of the ink ribbon extending between the ribbon roll mounted on the second spool and the fourth guide and the direction of the ink ribbon extending between the second guide and the fourth guide is an acute angle. can do. In this case, the fourth guide includes a component of force in the direction of the ink ribbon extending between the ribbon roll and the fourth guide, and a component of force in the direction of the ink ribbon extending between the second guide and the fourth guide. The resultant force acts. Therefore, the resultant force acting on the fourth guide can be further increased by making each of the angles formed acute. In this case, since the frictional force between the fourth guide and the ink ribbon is increased, it is possible to make the ink ribbon difficult to slide with respect to the fourth guide.

  In the first aspect, the second movement direction may be parallel to the first transport direction. That is, the direction in which the second guide can be moved coincides with the ink ribbon transport direction. In this case, when the second guide moves according to the tension of the ink ribbon, the movement of the second guide is not hindered by the ink ribbon. Therefore, the second guide can easily move in the second movement direction, and the second sensor can specify the tension of the ink ribbon with higher accuracy.

  In the first aspect, the control unit may specify the tension based on the second value, and specify the first outer diameter based on the specified tension and the first value. The second value of the second sensor does not depend on the second outer diameter of the ribbon roll mounted on the second spool. Therefore, the printing apparatus can always specify the tension of the ink ribbon with high accuracy regardless of the second outer diameter of the ribbon roll mounted on the second spool. In addition, since the first value of the first sensor depends on the first outer diameter of the ribbon roll mounted on the first spool, the printing apparatus uses the specified tension and the first value to determine the first spool. The first outer diameter of the ribbon roll attached to the is specified. Accordingly, the printing apparatus can specify not only the tension but also the first outer diameter with high accuracy.

  In the first aspect, the control unit specifies the first outer diameter based on the distance between the center of the first spool and the first guide, the specified tension, and the first value. May be. In this case, the printing apparatus can specify the first outer diameter of the ribbon roll mounted on the first spool, for example, by using a trigonometric function based on the distance between the center of the first spool and the first guide. .

  1st aspect WHEREIN: The 1st memory | storage part which memorize | stores the said 2nd value when the said 1st conveyance direction and the said 3rd conveyance direction orthogonally cross as a reference value, The said control part is a said 2nd sensor. The motor may be driven so that the second value output from the second reference value matches the reference value. In this case, the printing apparatus can directly specify the tension of the ink ribbon based on the second value. Therefore, the printing apparatus can easily execute the specification of the tension and the specification of the first outer diameter based on the specified tension.

  In the first aspect, the control unit may specify the tension and the first outer diameter when printing using the thermal head is not performed. When printing is performed by the printing apparatus, the thermal head comes into contact with the ink ribbon, so that tension is applied to the ink ribbon. When the first outer diameter is specified based on the applied tension, the accuracy may decrease. On the other hand, the printing apparatus specifies the first outer diameter when printing is not performed. Thereby, the printing apparatus can improve the accuracy of the specified first outer diameter.

  1st aspect WHEREIN: The 2nd memory | storage part which memorize | stores the drive table which links | relates the said 1st outer diameter and the rotational speed of the said motor is further provided, The said control part uses the said 1st value and the said 2nd value. The rotation speed of the motor may be determined from the identified first outer diameter with reference to the drive table, and the motor may be controlled so that the rotation speed is maintained. In this case, the printing apparatus can easily specify the rotational speed of the motor for transporting the ink ribbon at a desired speed based on the first outer diameter.

  A printing apparatus according to a second aspect of the present invention includes a first spool that can rotate around a rotation shaft, a second spool that can rotate around a rotation shaft, and at least one of the first spool and the second spool. , A thermal head provided in a part of a transport path of an ink ribbon transported between the first spool and the second spool, and the thermal head and the first of the transport paths. A first guide that is movably provided in a first movement direction at any position between the first spool and is biased toward one side of the first movement direction; When the ink ribbon is mounted between the second spool and the ink ribbon drawn out from the first spool, the ink ribbon is first brought into contact with the thermal head. The first guide, a first sensor capable of outputting a signal indicating a first value corresponding to the position of the first guide in the first movement direction, and the thermal head and the second of the transport paths. A second guide movably provided in the second movement direction at any position between the spool and biased toward one side of the second movement direction, the first spool and the first spool; The second guide that contacts the ink ribbon when the ink ribbon is mounted between the two spools and guides the ink ribbon between the thermal head and the second spool; and the second guide A second sensor capable of outputting a signal indicating a second value corresponding to the position in the second movement direction, and provided at any position of the transport path between the second sensor and the second spool. The second spoof A third guide that contacts the ink ribbon drawn out from the first ribbon and guides the ink ribbon toward the second guide; and the motor based on a first outer diameter of the ink ribbon mounted on the first spool. A control unit that controls, using the first value and the second value, the control unit specifies the tension acting on the ink ribbon and the first outer diameter. To do. According to the 2nd aspect, there can exist an effect similar to a 1st aspect.

2 is a diagram illustrating an outline of the printing apparatus 1 and a ribbon assembly 90. FIG. FIG. 6 is a diagram illustrating an operation of the first sensor assembly 4. It is a figure explaining the force F1 and tension | tensile_strength T which act on the 1st guide 42. FIG. It is a figure which shows operation | movement of the 2nd sensor assembly. It is a figure explaining the force F2 and tension T which act on the 2nd guide 52. FIG. FIG. 2 is a block diagram illustrating an electrical configuration of the printing apparatus 1. It is a figure for demonstrating the calculation formula of the radius ra of 9 A of 1st ribbon rolls. It is a figure for demonstrating the calculation formula of the radius ra of 9 A of 1st ribbon rolls. It is a figure which shows the approximation table 71A. It is a flowchart of a 1st main process. It is a flowchart of a 1st main process, Comprising: It is a continuation of FIG. It is a flowchart of a 1st main process, Comprising: It is a continuation of FIG. It is a flowchart of the 2nd main process. It is a flowchart of the 2nd main process, Comprising: FIG. 13 is a continuation. It is a flowchart of a 2nd main process, Comprising: FIG. 14 is a continuation. It is a flowchart of an initial setting process.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The printing apparatus 1 is a thermal transfer type printing apparatus. As shown in FIG. 1, the printing apparatus 1 has a box-shaped housing 10. A substrate 10 </ b> A is fixed inside the housing 10. Ribbon mounting portion 2, thermal head 3, first sensor assembly 4, second sensor assembly 5, guide shaft 60 (third guide shaft 61, fourth guide shaft 62, fifth guide shaft 63, sixth guide shaft 64), The control unit 7 (see FIG. 6) and the motor 80 (see FIG. 6) are provided on the substrate 10A and housed in the housing 10. Hereinafter, in order to facilitate understanding of the description of the drawings, the upper side, the lower side, the left side, the right side, the front side, and the rear side of the printing apparatus 1 are defined. The upper side, lower side, left side, right side, front side, and rear side of the printing apparatus 1 correspond to the upper side, lower side, left side, right side, front side, and back side of FIG. The front surface of the substrate 10A faces the front side, and the back surface of the substrate 10A faces the rear side.

<Ribbon assembly 90>
The printing apparatus 1 performs printing on the print medium P by heating the ink ribbon 9 of the ribbon assembly 90 accommodated in the housing 10 with the thermal head 3. The ribbon assembly 90 has core shafts 90 </ b> A and 90 </ b> B and an ink ribbon 9. The core shafts 90A and 90B are each cylindrical. The ink ribbon 9 is a belt-like film, and an ink layer is applied to the surface of a base material such as polyethylene terephthalate (PET). The ink layer includes, for example, a pigment component such as carbon and a binder component such as wax and / or resin. The ink is melted by heating and transferred to the printing medium P. The ink ribbon 9 may have functional layers such as a back coat layer, a release layer, and an adhesive layer as necessary. The ink ribbon 9 has one end connected to the side surface of the core shaft 90A and the other end connected to the side surface of the core shaft 90B.

  The ribbon assembly 90 is mounted on a ribbon mounting portion 2 (described later) of the printing apparatus 1 in a state where the ink ribbon 9 is wound around the core shaft 90A. The ink ribbon 9 wound around the core shaft 90A is referred to as “first ribbon roll 9A”. The ink ribbon 9 is unwound from the first ribbon roll 9A of the core shaft 90A in the course of printing by the thermal head 3, and will be described later with a first sensor assembly 4, a third guide shaft 61, a thermal head 3, and a fifth guide shaft 63. , Guided by the sixth guide shaft 64, the second sensor assembly 5, and the fourth guide shaft 62, and wound around the core shaft 90B. The ink ribbon 9 wound around the core shaft 90B is referred to as “second ribbon roll 9B”. The respective rotation directions of the core shaft 90A and the core shaft 90B when the ink ribbon 9 is fed from the first ribbon roll 9A and wound around the second ribbon roll 9B are referred to as “normal rotation directions”. The ink ribbon 9 is unwound from the second ribbon roll 9B when the core shaft 90A and the core shaft 90B rotate in the direction opposite to the normal rotation direction (hereinafter referred to as “reversing direction”). In some cases, the roll 9A may be wound up.

<Ribbon mounting part 2>
The ribbon mounting part 2 has a first spool 21 and a second spool 22. Each of the first spool 21 and the second spool 22 is rotatable about a rotation axis extending in the front-rear direction. The first spool 21 is provided approximately at the center in the up-down direction of the substrate 10A and on the right side of the center in the left-right direction. The second spool 22 is provided at the substantially vertical center of the substrate 10A and on the left side of the horizontal center. The core shaft 90A of the ribbon assembly 90 is attached to the first spool 21. The first ribbon roll 9 </ b> A wound around the core shaft 90 </ b> A is held by the first spool 21. The core shaft 90B of the ribbon assembly 90 is attached to the second spool 22. The second ribbon roll 9 </ b> B wound around the core shaft 90 </ b> B is held by the second spool 22. The first spool 21 is rotated by a first motor 81 (see FIG. 6, described later), and the second spool 22 is rotated by a second motor 82 (see FIG. 6, described later). Since the first spool 21 and the second spool 22 are rotated by different motors 80, they can be rotated at different rotational speeds.

  When the first spool 21 and the second spool 22 rotate counterclockwise when the printing apparatus 1 is viewed from the front side, the core shafts 90A and 90B rotate in the forward direction. At this time, the ink ribbon 9 is unwound from the first ribbon roll 9A and wound around the second ribbon roll 9B. When the first spool 21 and the second spool 22 rotate clockwise with the printing apparatus 1 viewed from the front, the core shafts 90A and 90B rotate in the reverse direction. The ink ribbon 9 is unwound from the second ribbon roll 9B and wound around the first ribbon roll 9A. Note that the rotation direction (clockwise direction or counterclockwise direction) described below indicates a direction when the printing apparatus 1 is viewed from the front side unless otherwise specified.

  The ink ribbon 9 extending between the first ribbon roll 9A and the second ribbon roll 9B according to the rotation of the first spool 21 and the second spool 22 is conveyed in the housing 10. The ink ribbon 9 is guided by coming into contact with a thermal head 3, a first sensor assembly 4, a second sensor assembly 5, a thermal head 3, and a guide shaft 60 which will be described later. That is, the thermal head 3, the first sensor assembly 4, the second sensor assembly 5, the thermal head 3, and the guide shaft 60 are respectively paths through which the ink ribbon 9 is transported (hereinafter referred to as “transport path R”). ").” Is arranged along a part of.

<First sensor assembly 4>
The first sensor assembly 4 is provided near the upper right corner of the substrate 10A. The first sensor assembly 4 is located above the first spool 21 in the vertical direction. The first sensor assembly 4 functions as a tension roller that maintains the tension of the ink ribbon 9 by changing the length of the transport path R of the ink ribbon 9, and functions as a position sensor that detects the position of the tension roller. Have Specifically, as shown in FIG. 2, the first sensor assembly 4 includes a first restricting portion 40 (see FIG. 1), a first support portion 41, a first guide shaft 42, a first magnet 43, and a first magnetic sensor. 44 and a first spring 45. The first restricting portion 40, the first support portion 41, the first guide shaft 42, and the first spring 45 constitute a tension roller, and the first magnet 43 and the first magnetic sensor 44 constitute a position sensor.

  The first support portion 41 is supported on the rear side of the substrate 10A so as to be movable in the vertical direction. The first guide shaft 42 has a cylindrical shape and extends from the front surface of the first support portion 41 toward the front side through a first restriction portion 40 described later. The first guide shaft 42 projects forward from the front surface of the substrate 10A. The first guide shaft 42 is rotatable around a rotation axis extending in the front-rear direction. As shown in FIG. 1, the 1st control part 40 prohibits the movement of the left-right direction of the 1st guide shaft 42, and controls the movement of the 1st guide shaft 42 to the up-down direction within a predetermined range. The 1st control part 40 is a long hole extended in the up-down direction provided in the board | substrate 10A, for example. The center position in the left-right direction of the first restricting portion 40 matches the position in the left-right direction of the rotation axis of the first guide shaft 42. As shown in FIG. 2, the first guide shaft 42 is located between the upper end reference position O (1) and the lower end maximum position Lm (1) in accordance with the vertical movement of the first support portion 41. Can be moved vertically. The first magnet 43 extends from the rear surface of the first support portion 41 toward the rear side. The first magnet 43 is a permanent magnet. The first guide shaft 42 and the first magnet 43 are movable in the vertical direction according to the movement of the first support portion 41. Hereinafter, the direction (vertical direction) in which the first guide shaft 42 and the first magnet 43 are movable is referred to as “first movement direction M1” (see FIG. 1).

  The first magnetic sensor 44 is provided on the substrate 10B extending rearward from the rear surface of the substrate 10A. The first magnetic sensor 44 faces the lower side of the first magnet 43. The 1st magnetic sensor 44 is for detecting the magnetic force of the 1st magnet 43, for example, is comprised by a Hall element. The magnitude of the magnetic force detected by the first magnetic sensor 44 changes according to the movement of the first magnet 43 in the first movement direction M1. The first spring 45 is a coil spring. One end portion of the first spring 45 is connected to the upper surface of the first support portion 41. The other end of the first spring 45 is connected to a substrate 10C that extends rearward from the rear surface of the substrate 10A. The first spring 45 is a tension spring that biases the first support portion 41, the first guide shaft 42, and the first magnet 43 upward. The spring constant of the first spring 45 is expressed as k (1).

  As shown in FIG. 1, the ink ribbon 9 contacts a part of the peripheral surface of the first guide shaft 42. The transport path R of the ink ribbon 9 extends from the first ribbon roll 9A mounted on the first spool 21 obliquely to the upper right, changes its direction by contacting the first guide shaft 42, and a third guide shaft described later. Extends down to 61.

As shown in FIG. 3, a downward force corresponding to the tension T of the ink ribbon 9 acts on the first guide shaft 42. More specifically, the first guide shaft 42 includes a downward component of the tension T of the ink ribbon 9 extending from the first guide shaft 42 toward the first ribbon roll 9A, and the first guide shaft 42 to the third guide. The resultant force with the tension T of the ink ribbon 9 extending toward the shaft 61 acts downward. An angle between a line segment extending from the center of the first spool 21 toward the right side and the ink ribbon 9 extending from the first ribbon roll 9A toward the first guide shaft 42 is denoted as θ1. At this time, the force F1 acting on the first guide shaft 42 is expressed by the following equation (1).
F1 = T (1 + sin θ1) (1)

  The first guide shaft 42 stops in a state where the force F1 and the biasing force of the first spring 45 are balanced. As shown in FIG. 2, the smaller the force F <b> 1 acting on the first guide shaft 42, the higher the first guide shaft 42 moves upward due to the urging force of the first spring 45. The greater the force F <b> 1 acting on the first guide shaft 42, the lower the first guide shaft 42 and the first magnet 43 move against the biasing force of the first spring 45.

  The first magnetic sensor 44 detects a magnetic force that changes according to the position of the first magnet 43 in the first movement direction M1. That is, the magnetic force detected by the first magnetic sensor 44 changes according to the magnitude of the tension T acting on the ink ribbon 9. Hereinafter, the output value of the first magnetic sensor 44 corresponding to the magnetic force detected by the first magnetic sensor 44 is referred to as a “first value”. The first sensor assembly 4 outputs a signal indicating the first value to the control unit 7 (see FIG. 6). Based on the first value indicated by the detected signal, the control unit 7 determines the position in the first movement direction M1 when the reference position O (1) of the first guide shaft 42 is used as a reference (hereinafter referred to as “first position”). Can be specified. Further, the control unit 7 can specify the force F1 based on the specified first position and the spring constant k (1) of the first spring 45.

<Third guide shaft 61>
As shown in FIG. 1, the third guide shaft 61 is provided in the vicinity of the lower right corner of the substrate 10A. The third guide shaft 61 is disposed below the first spool 21 in the vertical direction. That is, the third guide shaft 61 is located on the opposite side of the first guide shaft 42 with respect to the first spool 21 in the up-down direction.

  The third guide shaft 61 is cylindrical and extends from the front surface of the substrate 10A toward the front side. The third guide shaft 61 is rotatable around a rotation axis extending in the front-rear direction. The ink ribbon 9 contacts a part of the peripheral surface of the third guide shaft 61. The ink ribbon 9 extends downward from the first guide shaft 42 of the first sensor assembly 4, changes direction by contacting the third guide shaft 61, and extends toward the left side to the thermal head 3 described later. That is, in the left-right direction, the position of the right end of the third guide shaft 61 coincides with the position of the right end of the first guide shaft 42. Further, when the diameter of the third guide shaft 61 is the same as the diameter of the first guide shaft 42, the position of the rotation axis of the third guide shaft 61 matches the position of the rotation axis of the first guide shaft 42 in the left-right direction. To do. In response to the rotation of the first spool 21 and the second spool 22, the ink ribbon 9 moves up and down between the first guide shaft 42 and the third guide shaft 61 of the first sensor assembly 4. Hereinafter, the direction (vertical direction) of the portion of the transport path R extending between the first guide shaft 42 and the third guide shaft 61 of the first sensor assembly 4 is referred to as “second transport direction C2”. The second transport direction C2 is parallel to the first movement direction M1, which is the direction in which the first guide shaft 42 of the first sensor assembly 4 is movable.

<Thermal head 3>
The thermal head 3 is provided on the front surface of the substrate 10 </ b> A substantially in the first left-right direction and below the first spool 21 and the second spool 22. The thermal head 3 can be moved to a printing position 3A and a printing standby position 3B by a third motor 83 (see FIG. 6). The printing position 3A is a position where the lower end portion of the thermal head 3 is in contact with a platen roller Q (described later). The print standby position 3B is a position where the lower end portion of the thermal head 3 is separated from the platen roller Q and contacts or approaches the ink ribbon 9 extending in the left-right direction.

  When the thermal head 3 is disposed at the print standby position 3B, the ink ribbon 9 extends from the third guide shaft 61 toward the left side, contacts the lower end portion of the thermal head 3, changes its direction, and a fifth guide described later. It extends obliquely upward to the left toward the shaft 63. As the first spool 21 and the second spool 22 rotate, the ink ribbon 9 moves between the third guide shaft 61 and the thermal head 3 in the left-right direction. Hereinafter, the direction (left-right direction) of the portion of the transport path R extending between the third guide shaft 61 and the thermal head 3 disposed at the print standby position 3B is referred to as “first transport direction C1”. .

<Fifth guide shaft 63, sixth guide shaft 64>
The fifth guide shaft 63 and the sixth guide shaft 64 are each cylindrical, and extend from the front surface of the substrate 10A toward the front side. Each of the fifth guide shaft 63 and the sixth guide shaft 64 is rotatable about a rotation axis extending in the front-rear direction.

  The fifth guide shaft 63 is provided at a position diagonally above and to the left of the lower end portion of the thermal head 3 disposed at the print standby position 3B in the substrate 10A. The sixth guide shaft 64 is provided at a position on the lower left side of the substrate 10 </ b> A with respect to the fifth guide shaft 63. The ink ribbon 9 comes into contact with a part of the peripheral surfaces of the fifth guide shaft 63 and the sixth guide shaft 64. The ink ribbon 9 extends from the lower end portion of the thermal head 3 disposed at the print standby position 3 </ b> B obliquely to the upper left side, contacts the fifth guide shaft 63, changes its direction, and moves toward the sixth guide shaft 64. Extends diagonally downward. The ink ribbon 9 further changes its direction by contacting the sixth guide shaft 64 and extends to the left toward the second guide shaft 52 of the second sensor assembly 5 described later.

<Second sensor assembly 5>
The second sensor assembly 5 is provided near the lower left corner of the substrate 10A. A second guide shaft 52 (described later) of the second sensor assembly 5 is positioned below the second spool 22 in the vertical direction. The second sensor assembly 5 functions as a tension roller that maintains the tension of the ink ribbon 9 by changing the length of the transport path R of the ink ribbon 9, and functions as a position sensor that detects the position of the tension roller. Have Specifically, as shown in FIG. 4, the second sensor assembly 5 includes a second restriction portion 50 (see FIG. 1), a second support portion 51, a second guide shaft 52, a second magnet 53, and a second magnetic sensor. 54 and a second spring 55. A tension roller is configured by the second restriction unit 50, the second support unit 51, the second guide shaft 52, and the second spring 55, and a position sensor is configured by the second magnet 53 and the second magnetic sensor 54.

  The second support portion 51 is supported on the rear side of the substrate 10A so as to be movable in the left-right direction. The second guide shaft 52 has a cylindrical shape and extends from the front surface of the second support portion 51 toward the front side through a second restriction portion 50 described later. The second guide shaft 52 projects forward from the front surface of the substrate 10A. The second guide shaft 52 is rotatable about a rotation axis extending in the front-rear direction. As shown in FIG. 1, the second restricting unit 50 prohibits the vertical movement of the second guide shaft 52 and restricts the horizontal movement of the second guide shaft 52 within a predetermined range. The second restricting portion 50 is, for example, a long hole provided in the substrate 10A and extending in the left-right direction. The center position of the second restricting portion 50 in the vertical direction coincides with the vertical position of the rotation axis of the second guide shaft 52. In the vertical direction, the position of the lower end of the second guide shaft 52 coincides with the position of the lower end of the sixth guide shaft 64 and the position of the lower end of the thermal head 3 disposed at the print standby position 3B. Further, when the diameter of the second guide shaft 52 is the same as the diameter of the sixth guide shaft 64, the position of the rotation axis of the second guide shaft 52 coincides with the position of the rotation axis of the sixth guide shaft 64 in the vertical direction. To do. As shown in FIG. 4, the second guide shaft 52 extends from the left end reference position O (2) to the right end maximum position Lm (2) in accordance with the movement of the second support portion 51 in the left-right direction. Can be moved in the left-right direction. The second magnet 53 extends from the rear surface of the second support portion 51 toward the rear side. The second magnet 53 is a permanent magnet. The second guide shaft 52 and the second magnet 53 are movable in the left-right direction according to the movement of the second support portion 51. Hereinafter, the direction (left-right direction) in which the second guide shaft 52 and the second magnet 53 are movable is referred to as “second movement direction M2” (see FIG. 1).

  The second magnetic sensor 54 is provided on the substrate 10D extending rearward from the rear surface of the substrate 10A. The second magnetic sensor 54 faces the right side of the second magnet 53. The 2nd magnetic sensor 54 is for detecting the magnetic force of the 2nd magnet 53, for example, is comprised by a Hall element. The magnitude of the magnetic force detected by the second magnetic sensor 54 changes according to the movement of the second magnet 53 in the second movement direction M2. The second spring 55 is a coil spring. One end portion of the second spring 55 is connected to the left surface of the second support portion 51. The other end of the second spring 55 is connected to a substrate 10E that extends rearward from the rear surface of the substrate 10A. The second spring 55 is a tension spring that biases the second support portion 51, the second guide shaft 52, and the second magnet 53 to the left side. The spring constant of the second spring 55 is expressed as k (2).

  As shown in FIG. 1, the ink ribbon 9 contacts a part of the peripheral surface of the second guide shaft 52. When the second guide shaft 52 is disposed at a position separated Ls (see FIG. 4) on the right side with respect to the reference position O (2), the transport path R of the ink ribbon 9 is directed from the sixth guide shaft 64 to the left side. The second guide shaft 52 contacts the second guide shaft 52, changes its direction, and extends upward to the fourth guide shaft 62 described later. Hereinafter, the position separated Ls on the right side with respect to the reference position O (2) is referred to as “set position”. In a state where the second guide shaft 52 is disposed at the set position Ls, a portion from the sixth guide shaft 64 to the second guide shaft 52 in the transport path R, and from the second guide shaft 52 to the fourth guide shaft 62. It is orthogonal to the part.

  In response to the rotation of the first spool 21 and the second spool 22, the ink ribbon 9 moves in the left-right direction between the sixth guide shaft 64 and the second guide shaft 52 of the second sensor assembly 5. The direction (left-right direction) of the portion extending between the sixth guide shaft 64 and the second guide shaft 52 of the second sensor assembly 5 in the transport route R is the third guide shaft 61 in the transport route R. And the first transport direction C1, which is the direction of the portion extending between the thermal head 3 arranged at the print standby position 3B. A portion of the transport path R extending between the sixth guide shaft 64 and the second guide shaft 52 of the second sensor assembly 5 is the second guide shaft 52 of the thermal head 3 and the second sensor assembly 5. It corresponds to a part of the part extending between. That is, a part of the transport path R between the thermal head 3 disposed at the print standby position 3B and the second guide shaft 52 of the second sensor assembly 5 has a first transport direction C1. Match. The first transport direction C1 is parallel to the second movement direction M2, which is the direction in which the second guide shaft 52 of the second sensor assembly 5 can move.

As shown in FIG. 5, a rightward force corresponding to the tension T of the ink ribbon 9 acts on the second guide shaft 52. More specifically, the second guide shaft 52 includes a tension T of the ink ribbon 9 extending from the second guide shaft 52 toward the sixth guide shaft 64, and the second guide shaft 52 toward the fourth guide shaft 62. The resultant force of the right component of the tension T of the extending ink ribbon 9 acts in the right direction. An angle formed between the ink ribbon 9 extending from the second guide shaft 52 toward the sixth guide shaft 64 and the ink ribbon 9 extending from the second guide shaft 52 toward the fourth guide shaft 62 is denoted as θ4. At this time, the force F2 acting on the second guide shaft 52 is expressed by the following equation (2-1).
F2 = T (1 + cos θ4) (2-1)

Here, for example, when the second guide shaft 52 is disposed at the setting position Ls, the direction of the tension T of the ink ribbon 9 extending from the second guide shaft 52 toward the fourth guide shaft 62 is determined from the second guide shaft 52. The ink ribbon 9 extending toward the sixth guide shaft 64 is orthogonal to the direction of the tension T and extends upward. The force resulting from the movement of the second guide shaft 52 is only the component parallel to the movement direction (second movement direction M2) of the second guide shaft 52 in the tension T in the two directions. That is, the force F2 acting on the second guide shaft 52 arranged at the setting position Ls matches the tension T of the ink ribbon 9 extending from the second guide shaft 52 toward the sixth guide shaft 64, and the following equation ( 2-2).
F2 = T (2-2)

  The second guide shaft 52 is stationary in a state where the force F2 and the biasing force of the second spring 55 are balanced. As shown in FIG. 4, the smaller the force F <b> 2 acting on the second guide shaft 52, the more the second guide shaft 52 moves to the left due to the urging force of the second spring 55. The greater the force F <b> 2 acting on the second guide shaft 52, the more the second guide shaft 52 moves to the right against the urging force of the second spring 55. In a state where the second guide shaft 52 is disposed at the setting position Ls, the force F2 matches the tension T of the ink ribbon 9.

  The second magnetic sensor 54 detects a magnetic force that changes according to the position of the second magnet 53 in the second movement direction M2. That is, the magnetic force detected by the second magnetic sensor 54 changes according to the magnitude of the tension T acting on the ink ribbon 9. Hereinafter, the output value of the second magnetic sensor 54 corresponding to the magnetic force detected by the second magnetic sensor 54 is referred to as a “second value”. The second sensor assembly 5 outputs a signal indicating the second value to the control unit 7 (see FIG. 6). Based on the second value indicated by the detected signal, the control unit 7 specifies a position in the second movement direction M2 (hereinafter referred to as “second position”) with reference to the reference position O (2). it can. Further, the control unit 7 can specify the force F2 based on the specified second position and the spring constant k (2) of the splash 55.

<Fourth guide shaft 62>
As shown in FIG. 1, the fourth guide shaft 62 is provided near the upper left corner of the substrate 10A. The fourth guide shaft 62 is disposed above the second spool 22 in the vertical direction. That is, the fourth guide shaft 62 is located on the opposite side of the second sensor assembly 5 from the second guide shaft 52 in the up-down direction.

  The fourth guide shaft 62 has a cylindrical shape and extends from the front surface of the substrate 10A toward the front side. The fourth guide shaft 62 is rotatable about a rotation axis extending in the front-rear direction. The fourth guide shaft 62 is provided with a speed sensor 62A (see FIG. 6) capable of detecting the rotational speed of the fourth guide shaft 62. The ink ribbon 9 contacts a part of the peripheral surface of the fourth guide shaft 62. The ink ribbon 9 extends upward from the second guide shaft 52 disposed at the setting position Ls of the second sensor assembly 5, contacts the fourth guide shaft 62, changes its direction, and is mounted on the second spool. It extends diagonally downward to the right to the second ribbon roll 9B. In response to the rotation of the first spool 21 and the second spool 22, the ink ribbon 9 moves up and down between the second guide shaft 52 and the fourth guide shaft 62 of the second sensor assembly 5. Hereinafter, the direction (vertical direction) of the portion extending between the second guide shaft 52 and the fourth guide shaft 62 arranged at the set position Ls in the transport path R is referred to as “third transport direction C3”. . When the second guide shaft 52 is disposed at the set position Ls, the position of the left end of the fourth guide shaft 62 matches the position of the left end of the second guide shaft 52 in the left-right direction.

<Electrical Configuration of Printing Apparatus 1>
The electrical configuration of the printing apparatus 1 will be described with reference to FIG. The printing apparatus 1 includes a control unit 7. The control unit 7 includes a CPU that controls the printing apparatus 1 and various drive circuits that operate in accordance with instructions from the CPU. The various drive circuits are, for example, a circuit for supplying a signal (for example, drive current) to the motor 80 (first motor 81, second motor 82, third motor 83), and a signal (for example, drive current) to the thermal head. ), A circuit for driving the first sensor assembly 4, the second sensor assembly 5, and the speed sensor 62A, and A / D conversion of the received output signal. The control unit 7 includes a storage unit 71, a thermal head 3, a first sensor assembly 4, a second sensor assembly 5, a motor 80 (first motor 81, second motor 82, third motor 83), speed sensor 62A, and A communication interface (communication I / F) 72 is electrically connected via an interface circuit (not shown).

  The storage unit 71 includes various storage media such as a ROM, a RAM, and a flash memory. The storage unit 71 stores a program for processing executed by the control unit 7. The thermal head 3 generates heat in response to a signal output from the control unit 7. The motor 80 is a stepping motor that rotates in synchronization with a pulse signal. The first motor 81 rotates the first spool 21 according to the pulse signal output from the control unit 7. The second motor 82 rotates the second spool 22 according to the pulse signal output from the control unit 7. The third motor 83 rotates in accordance with the pulse signal output from the control unit 7 and moves the thermal head 3 between the printing position 3A and the printing standby position 3B (see FIG. 1). The first sensor assembly 4 outputs a signal indicating the first value to the control unit 7. The second sensor assembly 5 outputs a signal indicating the second value to the control unit 7. The speed sensor 62A is provided on the fourth guide shaft 62 (see FIG. 1). The speed sensor 62 </ b> A outputs a signal indicating the rotation speed of the fourth guide shaft 62 to the control unit 7. The communication I / F 72 is an interface element for performing communication with the external device 100 connected to the printing apparatus 1. The external device 100 is a terminal device used for the user to give various instructions to the printing apparatus 1.

<Outline of printing operation by printing apparatus 1>
As shown in FIG. 1, the print medium P is transported in a predetermined direction D at a predetermined transport speed (hereinafter referred to as “medium speed V”). The printing apparatus 1 has a position where the lower end of the printing apparatus 1 faces the printing surface (the upper surface in FIG. 1) of the printing medium P, and the direction from the right side to the left side of the printing apparatus 1 coincides with the direction D. The print medium P is disposed close to the print medium P. At this time, the direction D and the first transport direction C1 are parallel to each other. A platen roller Q is disposed on the opposite side of the printing apparatus 1 from the printing medium P.

  When the printing operation by the printing apparatus 1 is started, the thermal head 3 contacts the platen roller Q from above by moving from the print standby position 3B to the print position 3A. The ink ribbon 9 is pressed against the printing surface of the printing medium P according to the movement of the thermal head 3. The platen roller Q contacts the surface of the print medium P opposite to the print surface, and presses the ink ribbon 9 and the print medium P against the thermal head 3. In this state, rotation of the first spool 21 and the second spool 22 is started. The core shaft 90A and the core shaft 90B of the ribbon assembly 90 each rotate in the forward rotation direction. The ink ribbon 9 is unwound from the first ribbon roll 9 </ b> A of the first spool 21 and taken up by the second ribbon roll 9 </ b> B of the second spool 22. A portion of the ink ribbon 9 that contacts the print medium P moves to the left along the first transport direction C1. At the same time, the thermal head 3 is heated based on the print data stored in the storage unit 71. The ink on the ink ribbon 9 is transferred to the printing surface of the printing medium P. As described above, the print image for one block is printed on the print medium P. After the printing of the printing image for one block is completed, the thermal head 3 is moved from the printing position 3A to the printing standby position 3B. Thus, the printing operation for one block is completed.

  The printing apparatus 1 repeatedly executes the printing operation for one block as described above until a print end instruction is received from the external device 100. As a result, the print image for one block is repeatedly printed on the print medium P.

  In the above, in order for the printing apparatus 1 to perform appropriate printing on the print medium P, the medium speed V of the print medium P and the transport speed of the ink ribbon 9 (hereinafter referred to as “ribbon speed W”) match. Is preferred. Therefore, the ribbon speed W is controlled to coincide with the medium speed by controlling the rotation speeds of the first spool 21 and the second spool 22. The rotational speed of the first spool 21 for transporting the ink ribbon 9 at the same ribbon speed W as the medium speed V of the print medium P depends on the outer diameter of the first ribbon roll 9A mounted on the first spool 21. Change. This is because the amount per unit time of the ink ribbon 9 fed out from the first ribbon roll 9A changes according to the outer diameter of the first ribbon roll 9A even when the rotation speed of the first spool 21 is set to a predetermined value. Because. Similarly, the rotational speed of the second spool 22 for transporting the ink ribbon 9 at the same ribbon speed W as the medium speed V of the print medium P is also set to the outer diameter of the second ribbon roll 9B mounted on the second spool 22. Will change accordingly. That is, the control unit 7 of the printing apparatus 1 accurately specifies the outer diameters of the first ribbon roll 9A and the second ribbon roll 9B in order to transport the ink ribbon 9 at the same ribbon speed W as the medium speed V. There is a need.

<Calculation method of radius of first ribbon roll 9A>
A method for calculating the radius of the first ribbon roll 9A by the control unit 7 will be described. As shown in FIG. 7, the center of the first spool 21 is expressed as 2c, and the center of the first guide shaft 42 of the first sensor assembly 4 is expressed as 4c. The length in the left-right direction between the centers 2c and 4c is expressed as X, and the length in the vertical direction is expressed as Y. The radius of the first ribbon roll 9A is expressed as ra, and the radius of the first guide shaft 42 is expressed as rc. A line segment extending along the ink ribbon 9 extending between the first ribbon roll 9A and the first guide shaft 42 is denoted as Hi. The angle of the line segment Hi with respect to the left-right direction is expressed as θ1. A line segment connecting the centers 2c and 4c is denoted as Hc. The intersection of line segments Hi and Hc is denoted as Gh. The length between the centers 2c and 4c is denoted as L. The length between the center 2c and the intersection point Gh is denoted as La. The length between the center 4c and the intersection point Gh is denoted as Lc. The angle of the line segment Hc with respect to the left-right direction is expressed as an angle θ3. A contact point between the first ribbon roll 9A and the line segment Hi is denoted by Ga. The direction extending from the center 2c toward the contact point Ga is perpendicular to the line segment Hi. The angle of the line segment connecting the center 2c and the contact point Ga with respect to the line segment Hc is expressed as θ2. A contact point between the first guide shaft 42 and the line segment Hi is denoted as Gc. The direction extending from the center 4c toward the contact point Gc and the line segment Hi are orthogonal to each other. When the vertical length between the centers 2c and 4c is Y, the force F1 acting on the first spring 45 of the first sensor assembly 4 is denoted as f1 (Y). f1 (Y) is specified based on the spring constant k (1) of the first spring 45 and the amount of change from the natural length of the first spring 45 specified based on the length Y.

  As shown in FIG. 8, the center of the second guide shaft 52 of the second sensor is denoted as 5c. The center of the fourth guide shaft 62 is denoted as 62c. The length in the left-right direction between the centers 5c and 62c is expressed as x, and the length in the vertical direction is expressed as y. The radius of the second ribbon roll 9B is expressed as rb, and the radii of the fourth guide shaft 62 and the second guide shaft 52 are expressed as rd. An angle formed between the direction of the ink ribbon 9 extending from the second guide shaft 52 toward the sixth guide shaft 64 and the direction of extending from the second guide shaft 52 toward the fourth guide shaft 62 is expressed as θ4. When the length in the left-right direction between the centers 5c and 62c is x, the force F2 acting on the second spring 55 of the second sensor assembly 5 is denoted as f2 (x). f2 (x) can be specified based on the spring constant k (2) of the second spring 55 and the amount of change from the natural length of the second spring 55 specified based on the length x.

The angle θ3 is expressed by Expression (3-1) using the lengths X and Y.
θ3 = tan ⁻¹ (Y / X) (3-1)
The length L is represented by the formula (3-2) using the lengths X and Y.
L = √ (X ² + Y ² ) (3-2)
The length La is expressed by Expression (3-3) using the lengths ra, rc, and L.
La = (ra / (ra + rc)) × L (3-3)
The angle θ2 is expressed by Expression (3-4) using the lengths ra and La.
θ2 = cos ⁻¹ (ra / La) (3-4)
Expression (3-5) is derived from the relationship between Expressions (3-3) and (3-4).
θ2 = cos ⁻¹ ((ra + rc) / L) (3-5)
By transforming equation (3-4), equation (3-6) is derived.
((Π / 2) −θ2) = sin ⁻¹ (ra / La) (3-6)
Expression (3-7) is derived from the relationship between Expressions (3-3) and (3-6).
((Π / 2) −θ2) = sin ⁻¹ ((ra + rc) / L) (3-7)
The angle θ1 is represented by Expression (3-8) using the angles θ2 and θ3.
θ1 = (π / 2) − (θ2−θ3) = ((π / 2) −θ2 + θ3) (3-8)
Expression (3-9) is derived from the relationship between Expressions (3-1) and (3-7).
θ1 = sin ⁻¹ ((ra + rc) / L) + tan ⁻¹ (Y / X) (3-9)
Expression (3-10) is derived from the relationship between Expressions (3-2) and (3-9).
θ1 = sin ⁻¹ ((ra + rc) / √ (X ² + Y ² )) + tan ⁻¹ (Y / X) (3-10)

  In Expression (3-10), rc and X are predetermined fixed values that do not depend on the position of the first guide shaft 42 in the first movement direction M1. For this reason, the relationship between the angle θ1 and the radius ra of the first ribbon roll 9A can be specified by specifying the vertical length Y of the centers 2c and 4c.

Since the radii of the fourth guide shaft 62 and the second guide shaft 52 are both rd, the angle θ4 is expressed by Expression (4-1) using the lengths x and y.
θ4 = tan ⁻¹ (y / x) (4-1)
The force F2 received by the second guide shaft 52 of the second sensor assembly 5 according to the tension T of the ink ribbon 9 is expressed by equation (4-2) using T.
F2 = f2 (x) = T × (1 + cos θ4) (4-2)
By transforming equation (4-2), equation (4-3) is derived.
T = F2 / (1 + cos θ4) (4-3)
The force F1 received by the first guide shaft 42 of the first sensor assembly 4 according to the tension T of the ink ribbon 9 is expressed by equation (4-4) using T.
F1 = f1 (Y) = T × (1 + sin θ1) (4-4)
Expression (4-5) is derived from the relationship between Expressions (4-2) and (4-4).
F1 = F2 × (1 + sin θ1) / (1 + cos θ4)
(1 + sin θ1) = F1 × (1 + cos θ4) / F2
sin θ1 = (F1 × (1 + cos θ4) / F2) −1
θ1 = sin ⁻¹ ((F1 × (1 + cos θ4) / F2) −1) (4-5)
Expression (4-6) is derived from the relationship between Expressions (3-10) and (4-5).
sin ⁻¹ ((F1 × (1 + cos θ4) / F2) −1)
= Sin ⁻¹ ((ra + rc) / √ (X ² + Y ² )) + tan ⁻¹ (Y / X)
ra = sin (sin ⁻¹ (((F1 × (1 + cos θ4) / F2) −1) −tan ⁻¹ (Y / X)) × L−rc (4-6)

  In Expression (4-6), the length Y is specified from the vertical length between the first position specified based on the first value of the first sensor assembly 4 and the center 2c of the first spool 21. Is possible. The force F1 can be specified based on the spring constant k (1) of the first spring 45 and the amount of change from the natural length of the first spring 45 specified based on the length Y. The length L can be specified from the first position specified based on the first value of the first sensor assembly 4 and the position of the center 2 c of the first spool 21. That is, the length Y, the force F1, and the length L can all be specified based on the first value of the first sensor assembly 4. The length x can be specified from the length in the left-right direction between the second position specified based on the second value of the second sensor assembly 5 and the center 62 c of the fourth guide shaft 62. The force F2 can be specified based on the spring constant k (2) of the second spring 55 and the amount of change from the natural length of the second spring 55 specified based on the length x. The angle θ4 can be specified from the lengths x and y. That is, both the force F2 and the angle θ4 can be specified based on the second value of the second sensor assembly 5. Further, the length X and the radius rc are predetermined fixed values. Accordingly, the control unit 7 of the printing apparatus 1 applies the expression (4-6) based on the first value of the first sensor assembly 4 and the second value of the second sensor assembly 5 to thereby obtain the first ribbon. The radius ra of the roll 9A can be calculated.

The control unit 7 may perform the following approximate calculation in order to suppress an increase in processing load when calculating the radius ra of the first ribbon roll 9A using Expression (4-6). . Expression (5-1) is derived from Expression (3-9).
(1 + sinθ1)
= 1 + sin (sin ⁻¹ ((ra + rc) / L) + tan ⁻¹ (Y / X)) (5−1)
As an approximate expression of Expression (5-1), Expression (5-2) using coefficients a (i), b (i), and c (i) (i = 1, 2, 3,...) Is derived. Is done.
(1 + sin θ1) = a (i) × ra ² + b (i) × ra + c (i) (5-2)
As shown in FIG. 9, in the storage unit 71, the approximate expression specified by the coefficients a (i), b (i), and c (i) corresponding to the value of the length Y corresponds to each length Y. And is stored as an approximation table 71A.
Further, the equation (5-3) is derived by modifying the equation (4-4).
(1 + sin θ1) = F1 / T (5-3)

  The control unit 7 specifies the force F1 and the length Y based on the first value of the first sensor assembly 4. For example, a lookup table that defines the correspondence between the first value of the first sensor assembly 4 and the force F1 and the length Y is stored in the storage unit 71 in advance. The controller 7 specifies the force F1 and the length Y based on the first value of the first sensor assembly 4 by referring to the lookup table. The control unit 7 specifies the force F2 and the angle θ4 based on the second value of the second sensor assembly 5. For example, a lookup table that defines the correspondence between the second value of the second sensor assembly 5 and the force F2 and the angle θ4 is stored in the storage unit 71 in advance. The controller 7 specifies the force F2 and the angle θ4 based on the second value of the second sensor assembly 5 by referring to this lookup table. The control unit 7 specifies the tension T based on the specified force F2 and angle θ4. The control unit 7 substitutes the force F1 and the tension T into the formula (5-3), and specifies 1 + sin θ1. The control unit 7 selects an approximate expression corresponding to the specified length Y based on the approximate table 71A. The controller 7 calculates the radius ra of the first ribbon roll 9A by substituting 1 + sin θ1 into the selected approximate expression and solving the quadratic equation of ra.

  In this embodiment, the control part 7 performs the process which calculates the radius ra of the 1st ribbon roll 9A by the above-mentioned approximate calculation by the 1st main process or the 2nd main process mentioned later. Further, the control unit 7 specifies the radius rb of the second ribbon roll 9B based on the specified radius ra of the first ribbon roll 9A. The control unit 7 sets the rotational speeds of the first spool 21 and the second spool 22 for transporting the ink ribbon 9 at the same ribbon speed W as the medium speed V of the print medium P to the specified radii ra and rb. Identify accordingly. Accordingly, the control unit 7 conveys the ink ribbon 9 at the same ribbon speed W as the medium speed V of the print medium P.

  Note that, according to the above method, the control unit 7 controls the core shaft 90A as well as the radius ra of the first ribbon roll 9A after the ink ribbon 9 is fed out by rotating the core shaft 90A in the forward rotation direction. The radius ra of the first ribbon roll 9A after being wound by rotating in the reverse direction is also calculated. Furthermore, for example, when the core shaft 90A rotates in the reverse direction after the ink ribbon 9 has been fed out from the first ribbon roll 9A, the radius ra of the ink ribbon 9 wound around the core shaft 90A is calculated.

<Parameters, tables, etc. stored in the storage unit 71>
The storage unit 71 (see FIG. 6) stores a first drive table and a second drive table. The first drive table and the second drive table store the radius ra of the first ribbon roll 9 </ b> A and the rotation speed of the motor 80 in association with each other. The rotational speed of the motor 80 is indicated by the frequency of a pulse signal for rotating the motor 80. More specifically, it is as follows. In the first drive table, the radius ra of the first ribbon roll 9A and the ribbon speed W are associated with the frequency of a pulse signal for rotating the first motor 81 (hereinafter referred to as “first frequency”). By referring to the first drive table, the first frequency corresponding to the specific radius ra and the ribbon speed W is uniquely specified. In the second drive table, the radius rb of the second ribbon roll 9B and the ribbon speed W are associated with the frequency of the pulse signal for rotating the second motor 82 (hereinafter referred to as “second frequency”). By referring to the second drive table, the second frequency corresponding to the radius rb and ribbon speed W of the second ribbon roll 9B is uniquely specified. If a pulse signal is output to the first motor 81 at the first frequency specified by the first drive table and a pulse signal is output to the second motor 82 at the second frequency specified by the second drive table, it corresponds. The first spool 21 and the second spool 22 rotate so that the ink ribbon 9 is conveyed at the ribbon speed W.

  The storage unit 71 stores an initial value of the radius ra of the first ribbon roll 9A (hereinafter referred to as “first initial radius”) and an initial value of the radius of the second ribbon roll 9B (hereinafter referred to as “second initial radius”). ") Is stored. When the unused ribbon assembly 90 is used, the radius of the first ribbon roll 9A in the unused state is set as the first initial radius, and the radius of the core shaft 90B is set as the second initial outer diameter. When the radii ra and rb are calculated by the first main process or the second main process described later, the first initial radius is updated by the calculated radius ra, and the second initial radius is updated by the calculated radius rb. .

  The storage unit 71 further includes print data, a set position Ls (see FIG. 4), a set pulse number Xi, a set pulse number Xj, an additional pulse number Xp, margins Sa and Sb, a medium speed V, a print count Sd, and a specified count. Sp and the approximation table 71A (see FIG. 9) are stored. Among these, the print data and the medium speed V are set via the external device 100 (see FIG. 6). Specifically, the medium speed V is determined by the external device 100 based on the rotation speed of the platen roller Q, and is acquired at regular intervals via the communication I / F 72. Further, the storage unit 71 stores a force F2 (hereinafter referred to as “force Fs2”) in a state where the second guide shaft 52 is disposed at the set position Ls.

<First main process>
The first main process will be described with reference to FIGS. The first main process is started when the control unit 7 reads and executes the program stored in the storage unit 71 when an instruction for starting the printing operation is input via the external device 100. In the first main process, the control unit 7 is in a state where the second guide shaft 52 of the second sensor assembly 5 is disposed at the set position Ls (see FIG. 4) based on the second value of the second sensor assembly 5. Thus, the rotational speeds of the first motor 81 and the second motor 82 are controlled. In this state, the control unit 7 calculates the radii ra and rb based on the first value of the first sensor assembly 4 and the force Fs2 stored in the storage unit 71.

  In the following description, the control unit 7 rotates the first motor 81 in the direction in which the core shaft 90A of the ribbon assembly 90 rotates in the forward direction unless otherwise specified. In this case, the ink ribbon 9 is fed out from the first ribbon roll 9A. Further, the control unit 7 always rotates the second motor 82 in the direction in which the core shaft 90B of the ribbon assembly 90 rotates in the forward rotation direction. In this case, the ink ribbon 9 is wound around the second ribbon roll 9B. As a result, the transport direction of the portion of the ink ribbon 9 heated by the thermal head 3 coincides with the direction D (see FIG. 1) in which the print medium P is transported.

  When the first main process is started, the control unit 7 first drives the third motor 83 to move the thermal head 3 to the print standby position 3B (see FIG. 1). The controller 7 initializes the print count Sd by setting “0”.

  The control unit 7 performs the processes of S11 to S25 so that the ink ribbon 9 is stretched in the housing 10. The reason is that when the ink ribbon 9 is slack, the fourth guide shaft 62 does not rotate in accordance with the conveyance of the ink ribbon 9, and the speed sensor 62A may not be able to accurately detect the rotation speed of the fourth guide shaft 62. Because there is. The controller 7 outputs a pulse signal to the first motor 81 for the set number of pulses Xi (S11). Accordingly, the first motor 81 rotates by an angle corresponding to the set pulse number Xi. The controller 7 outputs the pulse signal to the second motor 82 for the set number of pulses Xj (S13). Thereby, the second motor 82 rotates by an angle corresponding to the set pulse number Xj. The control unit 7 specifies the second value based on the signal output from the second sensor assembly 5. The control unit 7 further specifies the second position based on the specified second value (S15).

  The control unit 7 determines whether the second position is within the range of “set position Ls ± margin Sa” in order to determine whether the second guide shaft 52 of the second sensor assembly 5 is disposed at the set position Ls. (S17). When it is determined that the second position is not within the range of “Ls ± Sa” (S17: NO), the control unit 7 determines that the second guide shaft 52 of the second sensor assembly 5 is not disposed at the set position Ls. to decide.

  When it is determined that the second position is not within the range of “Ls ± Sa” (S17: NO), the control unit 7 determines whether the second position is equal to or less than “Ls−Sa” (S21). When the specified second position is equal to or less than “Ls-Sa” (S21: YES), the control unit 7 determines that the second guide shaft 52 of the second sensor assembly 5 is on the left side of the set position Ls. Judge. In this case, the ink ribbon 9 is fed out excessively from the first ribbon roll 9A. The controller 7 outputs a pulse signal to the second motor 82 for the number of additional pulses Xp in order to put the ink ribbon 9 in a stretched state (S23). The second motor 82 rotates by an angle corresponding to the number of additional pulses Xp. The control unit 7 returns the process to S15. In response to the rotation of the second motor 82, the second ribbon roll 9B winds up the ink ribbon 9, so that the state in which the ink ribbon 9 is excessively fed out is improved.

  On the other hand, when the second position is equal to or greater than “Ls + Sa” (S21: NO), the second guide shaft 52 of the second sensor assembly 5 is located on the right side of the set position Ls. In this case, the feeding of the ink ribbon 9 from the first ribbon roll 9A is insufficient. In order to loosen the ink ribbon 9, the controller 7 outputs a pulse signal to the first motor 81 by the number of additional pulses Xp (S25). The first motor 81 rotates by an angle corresponding to the additional pulse number Xp. The control unit 7 returns the process to S15. In response to the rotation of the first motor 81, the first ribbon roll 9A feeds the ink ribbon 9, so that the state where the feeding of the ink ribbon 9 is insufficient is improved.

  The control unit 7 repeats the processes of S15 to S25 until the second position is within the range of “Ls ± Sa”. When the second position falls within the range of “Ls ± Sa” (S17: YES), the control unit 7 determines that the ink ribbon 9 is properly stretched in the housing 10. The control unit 7 advances the process to S31 (see FIG. 11).

  As shown in FIG. 11, the control unit 7 performs the processes of S <b> 31 to S <b> 41 in order to start the conveyance of the ink ribbon 9 before the start of printing. The control unit 7 reads the medium speed V stored in the storage unit 71 (S31). The control unit 7 reads the first initial radius and the second initial radius stored in the storage unit 71 (S33). The control unit 7 applies the ribbon speed W and the first initial radius that are the same as the read medium speed V to the first drive table, and acquires the first frequency (S35). The control unit 7 applies the ribbon speed W and the second initial radius that are the same as the read medium speed V to the second drive table, and acquires the second frequency (S37).

  The control unit 7 outputs a pulse signal to the first motor 81 at the first frequency acquired by the process of S35, and starts the rotation of the first motor 81 (S39). The control unit 7 outputs a pulse signal to the second motor 82 at the second frequency acquired by the process of S37, and starts the rotation of the second motor 82 (S41). In response to the start of rotation of the first spool 21 and the second spool 22, the ink ribbon 9 is conveyed from the first ribbon roll 9A toward the second ribbon roll 9B.

  The control unit 7 executes the processes of S43 to S47 in order to suppress an increase in the difference “V−W” between the medium speed V and the ribbon speed W. The control unit 7 specifies the rotational speed of the fourth guide shaft 62 based on a signal output from the speed sensor 62A (see FIG. 6). The controller 7 further specifies the ribbon speed W of the ink ribbon 9 based on the acquired rotation speed and the radius rd of the fourth guide shaft 62 (S43). The control unit 7 determines whether or not the difference “V−W” between the medium speed V read by the process of S31 and the ribbon speed W specified by the process of S43 is within a predetermined margin Sb ( S45).

  For example, the radius ra decreases as the ink ribbon 9 is fed out from the first ribbon roll 9A. As the difference between the first initial radius and the radius ra increases, the difference “V−W” between the ribbon speed W and the medium speed V increases. Similarly, the radius rb is increased by winding the ink ribbon 9 around the second ribbon roll 9B. The difference “V−W” increases as the difference between the second initial radius and the radius rb increases. The control unit 7 determines that the difference “V−W” is not within the range of Sb (S45: NO). The process proceeds to S47.

  When the ribbon speed W is higher than the medium speed V, the control unit 7 changes the first frequency and the second frequency so that the first motor 81 and the second motor 82 are decelerated, respectively (S47). When the ribbon speed W is smaller than the medium speed V, the control unit 7 changes the first frequency and the second frequency so that the first motor 81 and the second motor 82 are accelerated (S47). The control unit 7 returns the process to S39. The controller 7 outputs a pulse signal to the first motor 81 at the changed first frequency, and outputs a pulse signal to the second motor 82 at the changed second frequency. Accordingly, the rotational speeds of the first motor 81 and the second motor 82 are changed so that the difference “V−W” between the ribbon speed W and the medium speed V becomes small. When it is determined that the difference “V−W” is within the range of Sb (S45: YES), the control unit 7 advances the process to S49.

  The control unit 7 performs the processes of S49 to S57 in order to maintain the state where the second guide shaft 52 of the second sensor assembly 5 is disposed at the set position Ls (see FIG. 4). The control unit 7 specifies the second value based on the signal output from the second sensor assembly 5. The control unit 7 further specifies the second position based on the specified second value (S49). The control unit 7 determines whether the second position is within the range of “Ls ± Sa” in order to determine whether the second guide shaft 52 of the second sensor assembly 5 is disposed at the set position Ls (S51). .

  When it is determined that the second position is not within the range of “Ls ± Sa” (S51: NO), the control unit 7 determines that the second guide shaft 52 of the second sensor assembly 5 is not disposed at the set position Ls. to decide. The control unit 7 determines whether or not the second position is “Ls-Sa” or less (S53). When the second position is equal to or less than “Ls-Sa” (S53: YES), the ink ribbon 9 is excessively fed from the first ribbon roll 9A. The controller 7 changes the second frequency so that the second motor 82 is accelerated (S55). The control unit 7 returns the process to S41. When a pulse signal is output to the second motor 82 at the changed second frequency, the second motor 82 accelerates (S41). For this reason, since the amount of the ink ribbon 9 wound around the second ribbon roll 9B increases, the state in which the ink ribbon 9 is excessively fed out from the first ribbon roll 9A is improved.

  When the second position is equal to or greater than “Ls + Sa” (S53: NO), the feeding of the ink ribbon 9 from the first ribbon roll 9A is insufficient. The controller 7 changes the second frequency so that the second motor 82 is decelerated (S57). The control unit 7 returns the process to S39. When a pulse signal is output to the second motor 82 at the changed second frequency, the second motor 82 decelerates (S41). For this reason, since the amount of the ink ribbon 9 wound around the second ribbon roll 9B is reduced, the state where the ink ribbon 9 fed out from the first ribbon roll 9A is insufficient is improved.

  The control unit 7 repeats the processes of S49 to S57 until the second position is within the range of “Ls ± Sa”. When the second position falls within the range of “Ls ± Sa” (S51: YES), the controller 7 determines that the second guide shaft 52 of the second sensor assembly 5 is disposed at the set position Ls. . The control unit 7 advances the process to S61 (see FIG. 12).

  As illustrated in FIG. 12, the control unit 7 performs the processes of S <b> 61 to S <b> 69 in order to repeatedly execute the printing operation for one block. The control unit 7 drives the third motor 83 to move the thermal head 3 from the print standby position 3B (see FIG. 1) to the print position 3A (see FIG. 1) (S61). The control unit 7 heats the thermal head 3 based on the print data stored in the storage unit 71 and prints a print image for one block on the print medium P (S63). When the printing of the printing image for one block is completed, the control unit 7 drives the third motor 83 to move the thermal head 3 from the printing position 3A (see FIG. 1) to the printing standby position 3B (see FIG. 1). (S65). The control unit 7 updates the print count Sd stored in the storage unit 71 by adding 1 (S67). The processing of S61 to S67 corresponds to “printing operation for one block”.

  Based on the updated number of times of printing Sd, the control unit 7 determines whether the printing operation for one block has been repeatedly performed the specified number of times Sp (S69). When the number of times of printing Sd is less than the specified number of times Sp, the control unit 7 determines that the printing operation for one block has not been repeatedly executed the specified number of times Sp (S69: NO). The control unit 7 returns the process to S61. The control unit 7 repeats the printing operation for one block by executing the processes of S61 to S67. When the number of times of printing Sd is equal to or greater than the specified number of times Sp, the control unit 7 determines that the printing operation for one block has been repeatedly executed the specified number of times Sp (S69: YES). The control unit 7 advances the process to S71.

  The controller 7 performs the processes of S71 to S81 in order to calculate the radius ra of the first ribbon roll 9A and the radius rb of the second ribbon roll 9B. The control unit 7 specifies the first value based on the signal output from the first sensor assembly 4. The control unit 7 further specifies the first position based on the first value (S71). The control unit 7 specifies the force F1 and the length Y (see FIG. 7) based on the first position. The control unit 7 acquires the force Fs2 stored in the storage unit 71. In addition, since the state where the second guide shaft 52 of the second sensor assembly 5 is disposed at the set position Ls (see FIG. 4) is maintained, the force Fs2 matches the tension T of the ink ribbon 9. Therefore, the control unit 7 does not need to calculate the tension T from the force F2 and the angle θ4 specified based on the second value of the second sensor assembly 5.

  The controller 7 specifies 1 + sin θ1 by substituting the force Fs2 into the equation (5-3) as the tension T and further substituting the force F1 into the equation (5-3). The control unit 7 selects an approximate expression corresponding to the specified length Y based on the approximate table 71A. The controller 7 calculates the radius ra of the first ribbon roll 9A by substituting 1 + sin θ1 into the selected approximate expression and solving the quadratic equation of ra (S73).

The controller 7 calculates the radius rb of the second ribbon roll 9B based on the calculated radius ra (S75). For example, the control unit 7 calculates the radius rb using Expression (6). The first initial radius is expressed as Rs1, and the second initial radius is expressed as Rs2.
rb = Rs2 + (Rs1-ra) (6)

  The control unit 7 sets the calculated radius ra to the first initial radius and updates it (S77). The control unit 7 sets the calculated radius rb to the second initial radius and updates it (S77). The controller 7 initializes the print count Sd by setting “0” (S81). The control unit 7 returns the process to S31 (FIG. 11).

  The control unit 7 reads the updated first initial radius and second initial radius (S33). The control unit 7 applies the updated first initial radius to the first drive table, and acquires the first frequency (S35). The control unit 7 applies the updated second initial radius to the second drive table, and acquires the second frequency (S37). The controller 7 outputs a pulse signal to the first motor 81 at the first frequency, and starts the rotation of the first motor 81 (S39). The control unit 7 outputs a pulse signal to the second motor 82 at the second frequency, and starts the rotation of the second motor 82 (S41). As a result, the first spool 21 and the second spool 22 are rotated at a rotational speed corresponding to the calculated radii ra and rb, and the ink ribbon 9 is conveyed.

<Second main process>
The second main process will be described with reference to FIGS. The second main process is different from the first main process in that the radius ra of the first ribbon roll 9A is calculated in a state where the second guide shaft 52 of the second sensor assembly 5 is not disposed at the set position Ls. It is. The same processes as the first main process are denoted by the same reference numerals, and description thereof is omitted or simplified.

  The control part 7 performs the process of S11-S17, S21-S25. Accordingly, the control unit 7 outputs a pulse signal to the first motor 81 and the second motor 82 so that the ink ribbon 9 is stretched in the housing 10. When the second position falls within the range of “Ls ± Sa” (S17: YES), the control unit 7 determines that the ink ribbon 9 is in a tensioned state within the housing 10, and performs initial setting processing ( 16) is executed (S18).

  The initial setting process will be described with reference to FIG. In the initial setting process, initial values of the radius ra of the first ribbon roll 9A and the radius rb of the second ribbon roll 9B are specified (S101). The initial value of the radius ra of the first ribbon roll 9A and the initial value of the radius rb of the second ribbon roll 9B can be specified by various methods. For example, the initial value of the radius ra of the first ribbon roll 9A is specified from the rotation speed of the first motor 81 and the speed of the ink ribbon 9 based on the detection result of the speed sensor 62A. The initial value of the radius rb of the second ribbon roll 9B is specified from the rotation speed of the second motor 82 and the speed of the ink ribbon 9 based on the detection result of the speed sensor 62A. Alternatively, a sensor arm that is biased toward the center of the first spool 21 and that contacts the outer periphery of the first ribbon roll 9A may be provided. By detecting the position of this sensor arm with an encoder using magnetism or light, the initial value of the radius ra of the first ribbon roll 9A is specified. Similarly, the initial value of the radius rb of the second ribbon roll 9B can be specified by providing a sensor arm. Alternatively, a light source such as an LED is provided above the first ribbon roll 9A and the second ribbon roll 9B, and a photodiode array arranged in the left-right direction is provided below the first ribbon roll 9A and the second ribbon roll 9B. May be. Since the first ribbon roll 9A and the second ribbon roll 9B block the light from the light source, depending on the initial value of the radius ra of the first ribbon roll 9A and the radius rb of the second ribbon roll 9B, the photodiode array The position of the projected shadow changes. If the position of this shadow is specified based on the detection result by the photodiode array, the initial values of the radius ra of the first ribbon roll 9A and the radius rb of the second ribbon roll 9B can be specified by geometric calculation.

  The control unit 7 executes the processes of S125 to S131 so that the ink ribbon 9 is stretched in the housing 10. The control unit 7 specifies the second value based on the signal output from the second sensor assembly 5. The control unit 7 further specifies the second position based on the second value (S125). The control unit 7 determines whether the second position is within the range of “setting position Ls ± Sa” in order to determine whether the second guide shaft 52 of the second sensor assembly 5 is disposed at the setting position Ls ( S127). When it is determined that the second position is not within the range of “Ls ± Sa” (S127: NO), it is determined whether the second position is equal to or less than “Ls−Sa” (S131). When the specified second position is equal to or less than “Ls-Sa” (S131: YES), the control unit 7 determines that the second guide shaft 52 of the second sensor assembly 5 is on the left side of the set position Ls. Judge. In this case, the ink ribbon 9 is fed out excessively from the first ribbon roll 9A. The controller 7 outputs a pulse signal to the second motor 82 for the number of additional pulses Xp in order to put the ink ribbon 9 in a stretched state (S133). The second motor 82 rotates by an angle corresponding to the number of additional pulses Xp. The control unit 7 returns the process to S125.

  On the other hand, when the second position is equal to or greater than “Ls + Sa” (S131: NO), the second guide shaft 52 of the second sensor assembly 5 is located on the right side of the set position Ls. In this case, the feeding of the ink ribbon 9 from the first ribbon roll 9A is insufficient. In order to loosen the ink ribbon 9, the controller 7 outputs a pulse signal to the first motor 81 for the number of additional pulses Xp (S135). The first motor 81 rotates by an angle corresponding to the additional pulse number Xp. The control unit 7 returns the process to S125. The control unit 7 repeats the processes of S125 to S135 until the second position is within the range of “Ls ± Sa”. When the second position falls within the range of “Ls ± Sa” (S127: YES), the control unit 7 determines that the ink ribbon 9 is properly stretched in the housing 10. The control unit 7 ends the initial setting process and returns the process to the second main process (see FIG. 13).

  As shown in FIG. 13, after the initial setting process (S18) is completed, the control unit 7 stores the radius ra of the first ribbon roll 9A calculated by the initial setting process (see FIG. 16) in the storage unit 71. The first initial radius is set, and the first initial radius is updated (S19). The control unit 7 sets the radius rb of the second ribbon roll 9B calculated by the initial setting process to the second initial radius stored in the storage unit 71, and updates the second initial radius (S19). The control unit 7 proceeds to S31 (see FIG. 14).

  As shown in FIG. 14, the processes of S31 to S43 are the same as the first main process (see FIG. 11). The control unit 7 determines that the difference “V−W” between the medium speed V read from the storage unit 71 by the process of S31 and the ribbon speed W specified by the process of S43 is within a predetermined margin Sb. (S45). The control unit 7 determines that the difference “V−W” is within the range of Sb (S45: YES). The process proceeds to S61 (see FIG. 15). In the second main process, the processes of S49 to S57 (see FIG. 11) of the first main process are not executed. That is, in the second main process, the process for maintaining the state where the second guide shaft 52 of the second sensor assembly 5 is disposed at the set position Ls is omitted.

  As illustrated in FIG. 15, the control unit 7 repeats the printing operation for one block by executing the processes of S61 to S69. When it is determined that the printing operation for one block has been repeatedly performed Sp the specified number of times (S69: YES), the control unit 7 advances the process to S83.

  The controller 7 performs the processes of S83 to S93 in order to calculate the radius ra of the first ribbon roll 9A and the radius rb of the second ribbon roll 9B. The method of calculating the radii ra and rb differs from the first main process in that the tension T is calculated based on the second value of the second sensor assembly 5 without using the force Fs2 stored in the storage unit 71. is there.

  The control unit 7 specifies the first value based on the signal output from the first sensor assembly 4, and further specifies the first position based on the first value (S83). The control unit 7 specifies the force F1 and the length Y based on the first position. The control unit 7 specifies the second value based on the signal output from the second sensor assembly 5, and further specifies the second position based on the second value (S85). The control unit 7 specifies the length x based on the second position, and specifies the force F2 by applying it to the equation (4-2). The control unit 7 specifies the angle θ4 by applying the lengths x and y to the equation (4-1). The control unit 7 substitutes the force F2 and the angle θ4 into the equation (4-3), and calculates the tension T (S87).

  The controller 7 calculates 1 + sin θ1 by substituting the specified force F1 and tension T into the equation (5-3). The control unit 7 selects an approximate expression corresponding to the specified length Y based on the approximate table 71A. The control unit 7 substitutes 1 + sin θ1 for the selected approximate expression, and calculates the radius ra of the first ribbon roll 9A by solving the quadratic equation of ra (S89).

  The controller 7 calculates the radius rb of the second ribbon roll 9B based on the calculated radius ra (S91). The control unit 7 calculates the radius rb using Equation (6). The control unit 7 sets the calculated radius ra to the first initial radius and updates it (S93). The control unit 7 sets the calculated radius rb to the second initial radius and updates it (S93). The controller 7 initializes the print count Sd by setting “0” (S95). The control unit 7 returns the process to S31 (FIG. 14).

<Main functions and effects of this embodiment>
In the printing apparatus 1, the first sensor assembly 4 outputs a signal indicating a first value corresponding to the position of the first guide shaft 42 in the first movement direction M1. The position of the first guide shaft 42 varies depending on the magnitude of the force F1 = T (1 + sin θ1) corresponding to the tension acting on the ink ribbon 9. Here, θ1 changes in accordance with the radius ra of the first ribbon roll 9A attached to the first spool 21. The reason is that no other guide shaft for changing the transport direction of the ink ribbon 9 is provided between the first guide shaft 42 and the first spool 21, and the ink ribbon 9 fed out from the first spool 21 is not provided. This is because first guided by the first guide shaft 42. That is, the first sensor assembly 4 outputs a signal indicating a first value that depends on the radius ra of the first ribbon roll 9A. The second sensor assembly 5 outputs a signal indicating a second value corresponding to the position of the second guide shaft 52 in the second movement direction M2. The position of the second guide shaft 52 varies depending on the magnitude of the force F2 = T (1 + cos θ4) corresponding to the tension acting on the ink ribbon 9. Here, θ4 does not change according to the radius rb of the second ribbon roll 9B mounted on the second spool 22. The reason is that a fourth guide shaft 62 for changing the transport direction of the ink ribbon 9 is provided between the second guide shaft 52 and the second spool 22, and the ink ribbon 9 wound around the second spool 22 is provided. This is because the conveyance direction is changed between the second guide shaft 52 and the second spool 22 by being guided by the fourth guide shaft 62. That is, the second sensor assembly 5 outputs a signal indicating a second value that does not depend on the radius rb of the second ribbon roll 9B.

  The control unit 7 specifies the force F1 and the length Y based on the first position specified according to the first value. In the first main process, the control unit 7 performs the first motor 81 and the second motor 82 so that the second guide shaft 52 is disposed at the set position Ls based on the second position specified according to the second value. To control. In this state, the control unit 7 reads the force Fs2 from the storage unit 71. The force Fs2 matches the tension T of the ink ribbon 9 when the second guide shaft 52 is disposed at the set position Ls. On the other hand, in the second main process, the control unit 7 specifies the tension T based on the second value specified according to the second value. That is, in both the first main process and the second main process, the tension T of the ink ribbon 9 is derived using the first value and the second value.

  Further, the control unit 7 calculates the radius ra of the first ribbon roll 9A based on the force F1, the tension T, and the length Y. The controller 7 further calculates the radius rb of the second ribbon roll 9B based on the radius ra.

  In the above method, when the radius ra and the tension T are specified, the rotational speeds of the first spool 21 and the second spool 22 are not referred to. Accordingly, even when the rotational speeds of the first spool 21 and the second spool 22 are variably controlled, the printing apparatus 1 sets the radius ra of the first ribbon roll 9A attached to the first spool 21 to the first value. And it can specify with a sufficient precision using a 2nd value.

  The third guide shaft 61 guides the ink ribbon 9 in the first transport direction C1 with the thermal head 3 and the ink ribbon 9 with the first guide shaft 42 of the first sensor assembly 4 in the second transport direction. Guide to C2. The first guide shaft 42 is positioned opposite to the third guide shaft 61 with respect to the first spool 21 in the second transport direction C2. In this case, the direction of the ink ribbon 9 extending between the first ribbon roll 9A and the first guide shaft 42 and the direction of the ink ribbon 9 extending between the third guide shaft 61 and the first guide shaft 42 are formed. The angle can be an acute angle. The force F1 acting on the first guide shaft 42 includes a component of force in the direction of the ink ribbon 9 extending between the first ribbon roll 9A and the first guide shaft 42, and the first guide shaft 42 and the third guide. This is expressed as a resultant force with a force component in the direction of the ink ribbon 9 extending between the shaft 61. Therefore, the resultant force acting on the first guide shaft 42 can be increased by making each angle formed as an acute angle. In this case, since the first guide shaft 42 is easily moved according to the tension T of the ink ribbon 9, the first sensor assembly 4 can accurately detect the force F1 according to the tension T of the ink ribbon 9.

  In the printing apparatus 1, the first movement direction M <b> 1 in which the first guide shaft 42 of the first sensor assembly 4 can move and the second conveyance direction C <b> 2 of the ink ribbon 9 are parallel to each other. In this case, when the first guide shaft 42 moves according to the tension T of the ink ribbon 9, the movement of the first guide shaft 42 is not hindered by the ink ribbon 9. Accordingly, the first guide shaft 42 is easily moved in the first movement direction M1. For this reason, the first sensor assembly 4 can detect the force F1 corresponding to the tension T of the ink ribbon 9 with higher accuracy.

  The thermal head 3 disposed at the print standby position 3B and the second guide shaft 52 of the second sensor assembly 5 guide the ink ribbon 9 in the first transport direction C1. The fourth guide shaft 62 guides the ink ribbon 9 in the third transport direction C3 different from the first transport direction C1 with the second guide shaft 52. The second guide shaft 52 is positioned opposite to the fourth guide shaft 62 with respect to the second spool 22 in the third transport direction C3. In this case, the direction of the ink ribbon 9 extending between the second ribbon roll 9B and the fourth guide shaft 62 and the direction of the ink ribbon 9 extending between the second guide shaft 52 and the fourth guide shaft 62 are formed. The angle can be an acute angle. The fourth guide shaft 62 includes a force component in the direction of the ink ribbon 9 extending between the second ribbon roll 9 </ b> B and the fourth guide shaft 62, and the second guide shaft 52 and the fourth guide shaft 62. A resultant force with a force component in the direction of the ink ribbon 9 extending therebetween acts. Therefore, the resultant force acting on the fourth guide shaft 62 can be increased by making the angles formed by the respective acute angles. In this case, the ink ribbon 9 can be made difficult to slide with respect to the fourth guide shaft 62. For this reason, the conveyance speed of the ink ribbon 9 can be accurately detected by the speed sensor 62A provided on the fourth guide shaft 62.

  In the printing apparatus 1, the second movement direction M <b> 2 in which the second guide shaft 52 can move and the first conveyance direction C <b> 1 of the ink ribbon 9 are parallel. In this case, when the second guide shaft 52 moves according to the tension T of the ink ribbon 9, the movement of the second guide shaft 52 is not hindered by the ink ribbon 9. Accordingly, the second guide shaft 52 is easily moved in the second movement direction M2. For this reason, the second sensor assembly 5 can specify the force F2 corresponding to the tension T of the ink ribbon 9 with higher accuracy.

  In the first main process, the control unit 7 specifies the second position based on the second value of the second sensor assembly 5. The controller 7 controls the rotation of the first motor 81 and the second motor 82 so that the second position is continuously arranged at the set position Ls. The control unit 7 reads the force Fs2 stored in the storage unit 71 as the tension T of the ink ribbon 9. The control unit 7 specifies the radius ra of the first ribbon roll 9 </ b> A based on the read tension T and the first value of the first sensor assembly 4. In the second main process, the control unit 7 directly calculates the tension T based on the second value of the second sensor assembly 5. The control unit 7 specifies the radius ra of the first ribbon roll 9A based on the calculated tension T and the first value of the first sensor assembly 4.

  In the above, the second value of the second sensor assembly 5 does not depend on the radius rb of the second ribbon roll 9B. Therefore, the control unit 7 can always specify the tension T of the ink ribbon 9 with high accuracy regardless of the radius rb of the second ribbon roll 9B. Further, the control unit 7 specifies the radius ra of the first ribbon roll 9A using the specified tension T and the first value. For this reason, the control unit 7 can specify not only the tension T but also the radius ra with high accuracy.

  Based on the length X in the left-right direction between the center 2c of the first spool 21 and the center 4c of the first guide shaft 42 of the first sensor assembly 4, the tension T, and the first value. Based on the specified length Y, the radius ra of the first ribbon roll 9A is specified. In this case, the control unit 7 can specify the radius ra of the first ribbon roll 9A by using, for example, a trigonometric function based on the length between the centers 2c and 4c.

  The second guide shaft 52 of the second sensor assembly 5 when the first transport direction C1 and the third transport direction C3 are orthogonal to each other is disposed at the set position Ls. The storage unit 71 stores a set position Ls. In the first main process, the control unit 7 specifies the second position based on the second value of the second sensor assembly 5. The controller 7 controls the rotational speeds of the first motor 81 and the second motor 82 so that the second position coincides with the set position Ls, whereby the second guide shaft 52 is placed at the set position Ls. Can be maintained. In this case, the control unit 7 can directly specify the tension T of the ink ribbon 9 by reading the force Fs2 stored in the storage unit 71. Therefore, the control unit 7 can easily specify the tension T.

  During the printing operation, the thermal head 3 is disposed at the printing position 3A. In this case, a stronger tension is applied to the ink ribbon 9 than when the thermal head 3 is disposed at the print standby position 3B. If the tension T of the ink ribbon 9 is calculated based on the applied tension, the accuracy may decrease. On the other hand, the controller 7 repeats the printing operation for one block by the prescribed number Sp, then moves the thermal head 3 to the print standby position 3B, and then calculates the tension T and the radius ra. That is, the control unit 7 does not calculate the tension T and the radius ra when printing is performed with the thermal head 3 disposed at the printing position 3A. Since the control unit 7 calculates the tension T in a state where the tension applied to the ink ribbon 9 by the thermal head 3 is relatively small, the control unit 7 can calculate the tension T with high accuracy. Therefore, the control unit 7 can increase the accuracy of the radius ra calculated based on the tension T.

  In the first drive table, the first frequency is associated with the radius ra and the ribbon speed W of the first ribbon roll 9A. The control unit 7 specifies the first frequency by referring to the first drive table based on the calculated ra and the medium speed V. In the second drive table, the second frequency is associated with the radius rb and the ribbon speed W of the second ribbon roll 9B. The control unit 7 specifies the second frequency by referring to the second drive table based on the calculated rb and the medium speed V. The controller 7 outputs a pulse signal to the first motor 81 at the first frequency and outputs a pulse signal of the second motor 82 at the second frequency, thereby causing the ink ribbon 9 to have the same ribbon speed W as the medium speed V. Can be transported by. As described above, the control unit 7 can easily set the frequency of the signal output to the motor 80 to transport the ink ribbon 9 at the same ribbon speed W as the medium speed V based on the first drive table and the second drive table. Can be identified.

<Modification>
The present invention is not limited to the above embodiment, and various modifications can be made. In the first main process and the second main process, the control unit 7 may drive the first motor 81 and the second motor 82 such that the core shafts 90A and 90B of the ribbon assembly 90 rotate in the reverse direction. . That is, the control unit 7 may feed out the ink ribbon 9 from the second ribbon roll 9 </ b> B attached to the second spool 22 and wind the ink ribbon 9 around the first ribbon roll 9 </ b> A attached to the first spool 21. . For example, after the printing operation for one block is completed, the control unit 7 changes the rotation directions of the first motor 81 and the second motor 82 during the printing until the next printing operation for one block is started. The direction may be reversed.

  The printing apparatus 1 may have a configuration including only the second motor 82. In this case, the first spool 21 may be provided with an applying mechanism for applying a predetermined back tension to the ink ribbon 9 in order to prevent the ink ribbon 9 from slackening. The imparting mechanism may be configured by, for example, a friction member that presses the first spool 21 in the axial direction, or a disc spring. The applying mechanism may apply a back tension to the ink ribbon 9 by applying a frictional force when the first spool 21 rotates. In addition, when it is set as the structure which has only the 2nd motor 82, the 2nd drive table in the said embodiment, ie, the 1st motor 81 and the 2nd motor 82, is used as a 2nd drive table for driving the 2nd motor 82. It goes without saying that a second drive table different from the second drive table in the case of being provided is used.

  The printing apparatus 1 may not have the fifth guide shaft 63 and the sixth guide shaft 64. In this case, the conveyance path R may extend linearly in the left-right direction between the third guide shaft 61 and the second guide shaft 52 of the second sensor assembly 5. The thermal head 3 may be provided in a part of the conveyance path R between the third guide shaft 61 and the second sensor assembly 5.

  The first sensor assembly 4 may specify the first position or the force F1 based on the first value detected by the first magnetic sensor 44. The first sensor assembly 4 may output a signal indicating the specified first position or force F <b> 1 to the control unit 7. The second sensor assembly 5 may specify the second position or force F <b> 2 based on the second value detected by the second magnetic sensor 54. The second sensor assembly 5 may output a signal indicating the specified second position or force F <b> 2 to the control unit 7.

  The first guide shaft 42 of the first sensor assembly 4 may be disposed at the same position as the first spool 21 in the vertical direction, or may be disposed below the first spool 21. The first guide shaft 42 may be disposed on the right side or the left side of the third guide shaft 61 in the left-right direction. Further, the movable direction of the first guide shaft 42 is not limited to the vertical direction, and may be movable in a direction inclined with respect to the vertical direction. That is, the first movement direction M1 and the second transport direction C2 may be different. The printing apparatus 1 may not include the third guide shaft 61. In this case, the transport path R may extend directly from the first guide shaft 42 toward the thermal head 3.

  The second guide shaft 52 of the second sensor assembly 5 may be disposed at the same position as the second spool 22 in the vertical direction, or may be disposed below the second spool 22. The second guide shaft 52 may be disposed above or below the sixth guide shaft 64 in the vertical direction. Further, the movable direction of the second guide shaft 52 is not limited to the left-right direction, and may be movable in a direction inclined with respect to the left-right direction. That is, the second moving direction M2 and the first transport direction C1 may be different.

  In the first main process, the control unit 7 specifies the tension T of the ink ribbon 9 based on the force Fs2 stored in the storage unit 71. On the other hand, the control unit 7 applies the force F2 (by applying the second position specified based on the second value of the second sensor assembly 5 to the equation (4-2) as in the second main process. You may specify (refer FIG. 8). Further, the control unit 7 specifies the angle θ4 (see FIG. 8) by applying the formula (4-1) based on the second value of the second sensor assembly 5, and further applies the formula (4-3). By doing so, the tension T may be specified. In the case of the first main process, since the second guide shaft 52 of the second sensor assembly 5 is disposed at the set position, the angle θ4 calculated as described above is 90 °, and the force F2 and the tension T coincide with each other. .

  The calculation method of the radius rb of the 2nd ribbon roll 9B is not limited to the method of using Formula (6). For example, the control unit 7 may store the entire length of the ink ribbon 9 of the ribbon assembly 90 in the storage unit 71. The control unit 7 calculates the length of the ink ribbon 9 of the second ribbon roll 9B based on the calculated radius ra of the first ribbon roll 9A, and based on the calculated length of the second ribbon roll 9B. The radius rb may be calculated. Further, the control unit 7 specifies the transport amount of the ink ribbon 9 based on the rotation speed detected by the speed sensor 62A, and based on the specified transport amount and the second initial radius, the control unit 7 determines the transport amount of the second ribbon roll 9B. The radius rb may be specified.

  The first drive table and the second drive table may not be stored in the storage unit 71. The controller 7 may directly calculate the rotational speed of the first motor 81 based on the calculated radius ra of the first ribbon roll 9A and the medium speed V. The control unit 7 may directly calculate the rotation speed of the second motor 82 based on the calculated radius rb of the second ribbon roll 9B and the medium speed V. The control unit 7 may specify the frequency of a signal for rotating the motor 80 at the calculated rotation speed.

  The control unit 7 may acquire the rotational speed detected by the platen roller Q and specify the medium speed V based on the rotational speed. The printing apparatus 1 may include a platen roller Q.

1: Printing device 2: Ribbon mounting part 3: Thermal head 4: 1st sensor 5: 2nd sensor 7: Control part 9: Ink ribbon 9A: 1st ribbon roll 9B: 2nd ribbon roll 21: 1st spool 22: Second spool M1: First movement direction M2: Second movement direction R: Transport path

Claims (11)

When a ribbon roll is attached to one of the first spool and the second spool, the ink ribbon is fed out from the ribbon roll, and the fed out ink ribbon is A ribbon mounting portion wound around the other of the first spool and the second spool;
A motor for rotating at least one of the first spool and the second spool;
A thermal head provided in a part of a transport path of the ink ribbon transported between the first spool and the second spool;
In the transport path, a position is provided so as to be movable in the first movement direction at any position between the thermal head and the first spool, and is urged toward one side in the first movement direction. A first guide that contacts the ink ribbon when the ink ribbon is mounted on the ribbon mounting portion and guides the ink ribbon between the thermal head and the first spool; ,
A signal that is a value corresponding to the position of the first guide in the first movement direction and that indicates a first value that depends on a first outer diameter of the ink ribbon mounted on the first spool can be output. 1 sensor,
In the transport path, a position is provided so as to be movable in the second movement direction at any position between the thermal head and the second spool, and is biased toward one side in the second movement direction. A second guide for contacting the ink ribbon between the thermal head and the second spool when the ink ribbon is mounted on the ribbon mounting portion; ,
A signal that can output a signal indicating a second value that is a value corresponding to the position of the second guide in the second movement direction and that does not depend on the second outer diameter of the ink ribbon mounted on the second spool. Two sensors,
A control unit for controlling the motor based on the first outer diameter;
With
The controller is
The printing apparatus, wherein the tension acting on the ink ribbon and the first outer diameter are specified using the first value and the second value. A third guide provided at any position between the thermal head and the first guide in the transport path;
The third guide is
When the ink ribbon is mounted on the ribbon mounting portion, the ink ribbon comes into contact with the ribbon, and guides the ink ribbon from the third guide toward the thermal head in the first transport direction;
The first guide is
When the ink ribbon is mounted on the ribbon mounting portion, the ink ribbon heading from the first guide toward the third guide is guided in the second transport direction;
The printing apparatus according to claim 1, wherein the printing apparatus is located opposite to the third guide with respect to the first spool in the second transport direction.   The printing apparatus according to claim 2, wherein the first movement direction is parallel to the second transport direction. A fourth guide provided at any position between the second guide and the second spool in the transport path;
The fourth guide is
When the ink ribbon is mounted on the ribbon mounting portion, the ink ribbon comes into contact with the ribbon, and guides the ink ribbon from the fourth guide toward the second guide in the third transport direction;
The second guide is
Guiding the ink ribbon from the second guide toward the thermal head in the first transport direction;
4. The printing apparatus according to claim 2, wherein the printing apparatus is positioned opposite to the fourth guide with respect to the second spool in the third transport direction. 5.   The printing apparatus according to claim 4, wherein the second movement direction is parallel to the first transport direction. The controller is
6. The tension according to claim 1, wherein the tension is specified based on the second value, and the first outer diameter is specified based on the specified tension and the first value. Printing device. The controller is
7. The first outer diameter is specified based on a distance between a center of the first spool and the first guide, the specified tension, and the first value. The printing apparatus as described. A first storage unit that stores the second value when the first transport direction and the third transport direction are orthogonal to each other as a reference value;
The controller is
The printing apparatus according to claim 4, wherein the motor is driven so that the second value output from the second sensor matches the reference value. The controller is
The printing apparatus according to claim 1, wherein when the printing using the thermal head is not performed, the tension and the first outer diameter are specified. A second storage unit that stores a drive table that associates the first outer diameter with the rotation speed of the motor;
The controller is
From the first outer diameter specified using the first value and the second value, determine the rotational speed of the motor with reference to the drive table,
Controlling the motor such that the rotational speed is maintained;
The printing apparatus according to claim 1, wherein the printing apparatus is a printer. A first spool rotatable about a rotation axis;
A second spool rotatable about a rotation axis;
A motor for rotating at least one of the first spool and the second spool;
A thermal head provided in a part of a transport path of an ink ribbon transported between the first spool and the second spool;
In the transport path, a position is provided so as to be movable in the first movement direction at any position between the thermal head and the first spool, and is urged toward one side in the first movement direction. When the ink ribbon is mounted between the first spool and the second spool, the guide first comes into contact with the ink ribbon drawn from the first spool, and is directed toward the thermal head. The first guide for guiding the ink ribbon;
A first sensor capable of outputting a signal indicating a first value according to a position of the first guide in the first movement direction;
In the transport path, a position is provided so as to be movable in the second movement direction at any position between the thermal head and the second spool, and is biased toward one side in the second movement direction. 2 guides, which contact with the ink ribbon when the ink ribbon is mounted between the first spool and the second spool, and the ink ribbon between the thermal head and the second spool. Said second guide for guiding
A second sensor capable of outputting a signal indicating a second value corresponding to a position of the second guide in the second movement direction;
It is provided in any position between the second sensor and the second spool in the transport path, contacts the ink ribbon drawn out from the second spool, and uses the ink ribbon as the second guide. A third guide to guide,
A control unit for controlling the motor based on a first outer diameter of the ink ribbon mounted on the first spool;
With
The control unit specifies the tension acting on the ink ribbon and the first outer diameter using the first value and the second value.
A printing apparatus characterized by that.

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