Printer

Abstract

Provided is a printer in which a clutch spring can be easily fitted to a drive gear.　The printer comprises a drive gear 66, a clutch spring 68, and a drive cam 67. The drive gear 66 includes a gear 66A and a shaft 65. The shaft 65 includes a first shaft portion 66B, a tapered portion 66C, and a second shaft portion 66D. The clutch spring 68 is fitted onto the first shaft portion 66B. The tapered portion 66C extends upward from an upper end of the first shaft portion 66B, and has an outer diameter that becomes smaller in the upward direction. The second shaft portion 66D extends upward from an upper end of the tapered portion 66C. A second diameter R2 of the second shaft portion 66D is smaller than a first diameter R1 of the first shaft portion 66B. The clutch spring 68 has an inner diameter R4 that is smaller than the first diameter R1 and larger than the second diameter R2 when not fitted onto the first shaft portion 66B. The drive cam 67 is fitted onto the shaft 65 and includes a spring accommodating portion 67B. The spring accommodating portion 67B opens downward and accommodates the clutch spring 68.

Description

printer

[0001] The present invention relates to a printer.

[0002] The printer in Patent Document 1 includes a cassette loading section. A cassette containing an ink ribbon and other materials is loaded into the cassette loading section. The cassette includes a ribbon take-up roller that winds up the ink ribbon used in printing. The printer's cassette loading section is provided with a ribbon drive gear for rotating the ribbon take-up roller. A clutch spring is attached to the shaft of the ribbon drive gear to apply a constant rotational torque.

[0003] Japanese Patent Application Laid-Open No. 2022-72729

[0004] When attaching the clutch spring to the ribbon drive gear during the printer manufacturing process, the diameter of the clutch spring must be manually expanded, which makes the installation of the clutch spring to the ribbon drive gear a cumbersome process for the worker.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a printer in which a clutch spring can be easily attached to a drive gear.

[0006] The printer according to the present invention comprises: a mounting section into which a cassette having an ink ribbon used for printing and a take-up spool for taking up the ink ribbon can be mounted; a drive gear including a gear that rotates by the driving force of a drive source and a shaft that rotates together with the gear and extends upward from the gear and is exposed in the mounting section; an annular clutch spring mounted on the shaft; and a drive cam that is mounted on the shaft and is capable of engaging with the take-up spool on its outer surface, and is rotated by torque imparted by the clutch spring when the shaft rotates, thereby rotating the take-up spool, and the shaft is The clutch spring is provided with a first shaft portion extending upward from the gear and on which the clutch spring is attached, a tapered portion extending upward from the upper end of the first shaft portion and having an outer diameter that decreases as it extends upward, and a second shaft portion extending upward from the upper end of the tapered portion, wherein a second diameter that is the maximum outer diameter of the second shaft portion is smaller than a first diameter that is the maximum outer diameter of the first shaft portion, and the clutch spring has an inner diameter that is smaller than the first diameter and larger than the second diameter when not attached to the first shaft portion, and the drive cam is provided with a spring accommodating portion that opens downward and accommodates the clutch spring.

[0007] In the printer described above, when the clutch spring is not attached to the first shaft portion, the inner diameter of the clutch spring is smaller than the first diameter of the first shaft portion and larger than the second diameter. During manufacturing, the worker first inserts the clutch spring into the second shaft portion. In this case, the clutch spring is inserted, for example, up to the periphery of the tapered portion. Then, the worker attaches the drive cam to the drive gear shaft from above. In this case, the spring accommodating portion of the drive gear abuts against the clutch spring and moves downward. The clutch spring moves toward the first shaft portion via the tapered portion while expanding its inner diameter. Once the drive cam is attached to the drive gear, the clutch spring is attached to the first shaft portion. Therefore, the printer allows for easy attachment of the clutch spring to the drive gear.

[0008] In the present invention, during the process of attaching the drive cam to the shaft, the spring accommodating portion may abut against the clutch spring from above and move it downward, thereby attaching the clutch spring to the first shaft portion. Therefore, the printer can easily attach the clutch spring to the drive gear.

[0009] In the present invention, a hook may be provided on the second shaft portion, the hook having an extending portion extending in the vertical direction and a protruding portion protruding from an upper end of the extending portion radially outward from the shaft, the protruding portion being located above the upper end of the drive cam when the drive cam is attached to the shaft and protruding radially outward beyond the inner wall of the drive cam. In the printer, the vertical position of the drive cam relative to the drive gear is fixed.

[0010] In the present invention, the extension portion may be flexible and bend inward in the radial direction when the drive cam is attached to the shaft. When the drive cam is attached to the shaft, the hook bends inward in the radial direction. Therefore, the hook does not interfere with the attachment of the drive cam to the shaft.

[0011] In the present invention, the protrusion may have a tapered surface that slopes outward in the radial direction as it extends downward. When the drive cam is attached to the shaft, the tapered surface can smoothly guide the drive cam downward.

[0012] In the present invention, the shaft may be cylindrical and inserted through a shaft provided in the mounting portion, the drive cam may be inserted through the shaft, and the amount by which the protrusion protrudes radially outward beyond the inner wall of the drive cam may be greater than the radial length of the gap between the shaft and the inner wall of the hook. In the printer, even if the hook bends radially inward while the drive cam is attached to the shaft, the hook continues to engage with the drive cam. Therefore, the printer can more reliably prevent the drive cam from coming off the shaft.

[0013] In the present invention, the clutch spring may include a main body portion extending spirally in the up-down direction, a first arm portion extending from an upper end of the main body portion outward in the radial direction of the shaft, and a second arm portion extending from a lower end of the main body portion outward in the radial direction, and the clutch spring may have a symmetrical shape in the up-down direction. Because the clutch spring has a symmetrical shape in the up-down direction, an operator can insert the clutch spring onto the shaft without making a mistake in the orientation of the clutch spring.

[0014] In the present invention, the spring accommodating portion may include a disk-shaped upper wall that covers the clutch spring from above, and a peripheral wall that extends downward from the radially outer end of the upper wall and covers the clutch spring from the radially outer side. The peripheral wall may have a notch formed in the lower end of the peripheral wall and extending upward from the lower end of the peripheral wall. The notch has a first portion having a first circumferential length and a second portion that extends upward from the circumferential center of the first portion and has a second circumferential length shorter than the first length. The first arm may abut against the second portion to be positioned in the circumferential direction, and the second arm may be disposed on the first portion. The position of the second arm of the clutch spring relative to the first arm may vary due to dimensional errors. Because the length of the first portion is longer than the length of the second portion, the second arm of the clutch spring fits into the first portion. Furthermore, the second arm of the clutch spring does not abut against the first portion even when the position varies due to dimensional errors. Therefore, the torque of the clutch spring is appropriately applied to the drive cam.

[0015] In the present invention, the second portion may be provided with a first wall extending radially inward from an end portion on one side in the circumferential direction and a second wall extending radially inward from an end portion on the other side in the circumferential direction, the first wall abutting against the first arm portion from one side in the circumferential direction, and the second wall abutting against the first arm portion from the other side in the circumferential direction. The second portion can abut against the first arm portion more reliably by the first wall and the second wall.

[0016] In the present invention, the radially outer end of the first arm may be positioned radially inward from the second portion, and the radially outer end of the second arm may be positioned radially inward from the first portion. In the printer, the clutch spring is housed inside the spring housing. This reduces the possibility of a worker or printer user coming into contact with the clutch spring during work.

[0017] In the present invention, the drive gear may further include a third shaft portion extending upward from the second shaft portion and having a third diameter smaller than the inner diameter of the clutch spring when the clutch spring is not attached to the first shaft portion, and the third shaft portion may be provided with a transmission gear for transmitting the driving force to the cassette. When it is necessary to transmit driving force to the cassette, the drive gear requires greater torque. Therefore, the diameter of the clutch spring must be smaller. Even in this case, the operator can easily attach the clutch spring to the drive gear. Furthermore, since the third shaft portion is located above the second shaft portion, the shaft becomes longer toward the top. Even in this case, since the third diameter of the third shaft portion is smaller than the inner diameter of the clutch spring, the clutch spring can be smoothly moved to the first shaft portion.

[0018] In the present invention, the drive gear and the drive cam may be made of different materials. If the drive gear and the drive cam were made of the same material, resonance would likely occur during friction, causing the sliding load to become unstable. This would result in unstable torque when winding the ink ribbon. Therefore, by combining a drive gear and a drive cam made of different materials, the printer can achieve stable torque when winding the ink ribbon.

[0019] 13A and 13B are perspective views of the printer 1. FIG. 13B is a perspective view of the printer 1 with the rear cover 3 removed. FIG. 13C is a perspective view of the printing unit 50. FIG. 13D is a perspective view of the platen unit 80. FIG. 13E is a front view of the drive shaft 63. FIG. 13F is an exploded perspective view of the drive shaft 63. FIG. 13G is a cross-sectional view of the spring accommodating section 67B taken along the line B-B. FIG. 13G is a cross-sectional view of the spring accommodating section 67B taken along the line C-C. FIG. 13H is a cross-sectional view of the drive shaft 63 taken along the line A-A. FIG. 13I is a perspective view of the tape cassette 100. FIG. 13J is an exploded perspective view of the tape cassette 100. FIG. 13J is a plan view showing the heat sink 72 and print head 71 positioned with the jig 140. FIG. 13J is a plan view showing the print head 71 positioned relative to the platen roller 82. FIG. 13J is a simplified plan view of an enlarged area C in FIG. 13A. FIG. 13J is a diagram showing the assembly procedure for the drive shaft 63. FIG. 13J is a table showing the specifications of each gear 131, 134, 137, 138, and 139.

[0020] A printer 1 and a tape cassette 100 according to one embodiment of the present invention will be described with reference to the drawings. The drawings are used to explain technical features that may be adopted by the present invention. In other words, the configurations and the like shown in the drawings are merely illustrative examples and are not intended to be limiting. In the description of this embodiment, the upper left, lower right, right, left, upper right, and lower left sides of FIG. 1 are respectively referred to as the lower, upper, right, left, front, and rear sides of the printer 1.

[0021] The configuration of the printer 1 will now be described. As shown in Figures 1 and 2, the printer 1 is a portable label printer. The printer 1 can print images on a tape 101 (see Figure 10) that is pulled out from a tape cassette 100 to create labels. The printer 1 can print images such as characters and figures on the tape 101.

[0022] 1 and 2, the printer 1 includes a housing 2, a rear cover 3, a display unit 4, and an input unit 5. The housing 2 is box-shaped and long in the front-to-rear direction, with an opening at the rear. An inner lid 6 is attached to the opening to protect the inside of the housing 2. A discharge passage 29 that penetrates in the front-to-rear direction and a fastening hole 2C that engages with an opening / closing portion 31 of the rear cover 3 are formed in a top wall 2A of the housing 2.

[0023] The rear cover 3 is removably attached to the housing 2. The rear cover 3 extends in the front-to-rear direction and has a recessed shape that is recessed upward. When attached, the rear cover 3 covers the entire rear surface of the housing 2 and closes the rear opening together with the inner lid 6.

[0024] The rear cover 3 has a window 35 at the front right position, through which the inside of the housing 2 can be seen from the outside. The position of the window 35 corresponds to the right side of the inside of the cassette loading section 10. When the tape cassette 100 is loaded into the cassette loading section 10, the user can see the label affixed to the top surface of the tape cassette 100 through the window 35. The label indicates the type of tape 101, etc.

[0025] The display unit 4 is, for example, a liquid crystal display, and is capable of displaying various types of information. The display unit 4 is provided in a position forward of the center in the front-to-rear direction on the underside 2B of the housing 2. The input unit 5 accepts input of various types of information through user operation. The input unit 5 is provided on the underside 2B of the housing 2, behind the display unit 4. The input unit 5 includes a plurality of keys, such as character keys, a print button, and an Esc key.

[0026] As shown in FIG. 2, the printer 1 includes a cassette loading section 10, a battery housing section 40, and a printing section 50 inside the housing 2. The cassette loading section 10 is configured to removably load a tape cassette 100. The cassette loading section 10 is formed in the inner cover 6 on the rear surface of the housing 2, at a position forward of the center in the front-to-rear direction. The cassette loading section 10 is recessed downward. The cassette loading section 10 has a recess bottom surface 11 and recess peripheral surfaces 12 to 15. The recess peripheral surfaces 12 to 15 connect to the edges of the recess bottom surface 11 and surround the periphery in the front-to-rear and left-to-right directions.

[0027] The battery housing section 40 houses a battery (not shown). The battery housing section 40 is formed in the inner lid 6 on the back of the housing 2, in a recessed shape that is recessed downward, at a position rearward of the center of the housing 2 in the front-to-rear direction. When the rear cover 3 is removed from the housing 2, the cassette loading section 10 and the battery housing section 40 are exposed to the outside of the printer 1 through an opening on the back of the housing 2. With the rear cover 3 removed from the housing 2, the user can replace the tape cassette 100 and the battery, respectively.

[0028] The printing unit 50 is a unit configured to print on the tape 101. The printing unit 50 is located in the front part of the housing 2, below the left end of the cassette loading unit 10. As shown in Figure 3, the printing unit 50 includes a base 51, a head unit 70, a platen unit 80, a drive mechanism 60, etc.

[0029] As shown in FIG. 3 , the base 51 is a metal plate that supports the components of the printing unit 50. The base 51 faces the top-bottom direction and extends longer in the front-to-back direction than in the left-to-right direction. The base 51 is provided with a mounting portion 141, pins 51A (see FIG. 12 ), pins 51B, a shaft 52, and the like. The mounting portion 141 is provided at the front end of the base 51 and in the center in the left-to-right direction. The mounting portion 141 extends upward. The mounting portion 141 faces the front-to-back direction. The mounting portion 141 is a metal plate that supports a cutting blade (not shown). In cooperation with the mounting portion 141, the cutting blade cuts the printed tape 101 (see FIG. 10 ). The pins 51A and 51B are provided at the front end of the base 51 and in the center in the left-to-right direction. The pin 51A is located in front of the pin 51B (see FIG. 12 ). The pins 51A and 51B are cylindrical and extend upward from the base 51. The shaft 52 is provided on the right side of the front end of the base 51 and extends upward.

[0030] As shown in FIG. 3 , the head unit 70 is assembled to the base 51. The head unit 70 includes a heat sink 72 and a print head 71. The heat sink 72 is a metal plate that supports the print head 71 and dissipates heat. The heat sink 72 is located at the front end of the base 51, in the center in the left-right direction. The heat sink 72 includes a lower end 72F and a right end 72U. The lower end 72F faces the plate surface in the up-down direction and extends longer in the front-to-rear direction than in the left-to-right direction. The lower end 72F has two holes 72A (see FIG. 12 ) and 72B. The hole 72A is located in front of the hole 72B. The holes 72A and 72B extend in the front-to-rear direction. Pins 51A and 51B are inserted through the holes 72A and 72B, respectively. In this state, the lower end 72F is fixed to the base 51 with screws 51C.

[0031] The right end 72U extends upward from the right end of the lower end 72F. The right end 72U faces the left-right direction and extends longer in the front-to-rear direction than in the up-to-down direction. The front upper end of the right end 72U protrudes higher than the lower upper end. The upper surface of the front upper end of the right end 72U functions as the support portion 18 when the tape cassette 100 is installed.

[0032] The print head 71 is fixed with adhesive to the left surface of the right end 72U of the heat sink 72. The print head 71 is a rectangular circuit board on which multiple heating elements 71A and a driver circuit unit 71B are mounted. The multiple heating elements 71A are arranged vertically at the front end of the left surface of the board. The driver circuit unit 71B is formed at the rear end of the left surface of the board and is electrically connected to a control unit (not shown) inside the housing 2 via a harness 73.

[0033] As shown in Figures 3 and 4, the platen unit 80 is disposed on the left side of the base 51. The rear end of the platen unit 80 is supported by a rotation shaft 53 so that the front end can swing left and right. Note that in Figure 4, the configuration of the parts before assembly is indicated by a two-dot chain line. The rotation shaft 53 of the platen unit 80 is located on the left side of the rear end of the base 51 and extends upward. By swinging the platen unit 80, the platen roller 82 can swing between a proximity position (see Figure 13) where it approaches the print head 71 and a remote position (see Figures 3 and 12) where it is away from the print head 71. For convenience, the orientation of each part of the platen unit 80 in the following description is based on the orientation of each part of the printer 1 when the platen roller 82 is in the proximity position.

[0034] The platen unit 80 includes a platen holder 81, a platen shaft 84, a platen roller 82, a platen gear 83, and a detection unit 91. The platen holder 81 is long in the front-to-rear direction and has a box shape that is open on the right side. The platen holder 81 has support holes 81A that penetrate vertically in the lower and upper walls at the rear end. The support holes 81A are supported by the rotation shaft 53 of the base 51. The lower and upper walls of the platen holder 81 have bulging portions 81B, 81B that bulge to the right at the front end. The bulging portions 81B, 81B have through-holes (not shown) that penetrate vertically. The platen roller 82 is rotatably supported between the bulging portions 81B, 81B.

[0035] The platen shaft 84 is an axial member that extends in the vertical direction. The platen shaft 84 has insertion holes 84A and 84B at its upper end and center in the vertical direction. Engagement pins 85 and 86 are inserted into the insertion holes 84A and 84B. The engagement pins 85 and 86 are rod members that are longer than the diameter of the platen shaft 84. When inserted into the insertion holes 84A and 84B, the engagement pins 85 and 86 each penetrate the platen shaft 84 in the radial direction. In addition, a groove 84C that engages with a retaining ring 87 is formed in the lower end of the platen shaft 84.

[0036] The platen roller 82 has a roller body 82A and a roller sleeve 82B. The roller sleeve 82B is a cylindrical member through which the platen shaft 84 is inserted. The roller sleeve 82B rotates on its axis together with the platen shaft 84. In addition, a notch 82E that penetrates the cylindrical wall surface in the radial direction is formed at the upper end of the roller sleeve 82B, in line with the position of the groove 82D. The roller body 82A is a cylindrical member that is fitted onto the outer peripheral surface of the middle part of the roller sleeve 82B. The roller body 82A rotates on its axis together with the platen shaft 84 and roller sleeve 82B.

[0037] The platen gear 83 is fixed to the upper end of a platen shaft 84 that protrudes upward from the bulge 81B on the upper wall side. The platen gear 83 is a so-called helical gear, with gear teeth twisted at a predetermined angle relative to the rotation axis L4 (see FIG. 11). An engagement pin 85 at the upper end of the platen shaft 84 engages with a groove 83B formed on the inner surface of a through hole 83A provided at the rotation center of the platen gear 83. The engagement pin 85 transmits torque from the platen gear 83 to the platen shaft 84. Therefore, the platen shaft 84 rotates together with the platen gear 83.

[0038] When the platen roller 82 is in the proximity position (see FIG. 13), the roller body 82A sandwiches the tape 101 and ink ribbon 104 between it and the print head 71. The platen gear 83 meshes with an output gear 131 of the tape cassette 100 (see FIGS. 10 and 11). The driving force of a drive shaft 63 (described below) is input to the platen roller 82 via the tape cassette 100 and the platen gear 83. As the platen roller 82 rotates, the roller body 82A transports the tape 101 sandwiched between it and the print head 71 toward the discharge path 29.

[0039] As shown in Figure 3, the platen holder 81 has a holding portion 81C located closer to the rear end than the middle portion in the front-to-rear direction. The holding portion 81C is concave and recessed to the left. The holding portion 81C holds a detection portion 91. The detection portion 91 is composed of a mechanical switch. The detection portion 91 is switched on and off by a detected portion 125 of the tape cassette 100 (see Figures 10 and 11). The detection portion 92 detects the cassette identification information provided to the tape cassette 100 based on the combination of on and off switches.

[0040] 3, the drive mechanism 60 includes a motor 61, a gear group 62, and a drive shaft 63, and is mounted on the base 51. The motor 61 is a drive source and is disposed at the rear end of the base 51. The drive force of the motor 61 is transmitted to the drive shaft 63, which is disposed on the right side of the front end of the base 51, by a gear group 62 which connects multiple gears. The motor 61, the gear group 62, and the base 51 are disposed below the inner lid 6 inside the housing 2.

[0041] The drive shaft 63 will be described with reference to FIGS. 5 to 9. The drive shaft 63 is inserted through the shaft 52 (see FIG. 3) provided on the base 51. The drive shaft 63 is exposed inside the cassette loading section 10 from an opening formed in the bottom surface 11 of the recess (see FIG. 2). When the tape cassette 100 is loaded into the cassette loading section 10, the drive shaft 63 is inserted into the take-up spool 107 (see FIG. 11) and input gear 134 (see FIG. 11) of the tape cassette 100 (see FIG. 9). Driving force transmitted from the motor 61 (see FIG. 3) is input to the drive shaft 63 via a gear group 62. The drive shaft 63 rotates the take-up spool 107 and input gear 134 by the driving force from the motor 61.

[0042] The drive shaft 63 includes a drive gear 66, a clutch spring 68, and a drive cam 67. The driving force of the motor 61 is transmitted to the drive gear 66 via the gear group 62. The drive gear 66 is made of, for example, a resin material. The drive gear 66 includes a gear 66A and a shaft 65. The gear 66A meshes with the downstream-most gear of the gear group 62 (see FIG. 3). The gear 66A rotates via the gear group 62 (see FIG. 3) by the driving force of the motor 61 (see FIG. 3). The shaft 65 extends upward from the gear 66A. The shaft 65 is cylindrical. The diameter of the shaft 65 is smaller than that of the gear 66A. The shaft 65 is inserted into the shaft 52 (see FIG. 3). The shaft 65 rotates around the shaft 52 (see FIG. 3) together with the gear 66A.

[0043] The shaft 65 includes a first shaft portion 66B, a tapered portion 66C, a second shaft portion 66D, and a third shaft portion 66E. The first shaft portion 66B extends upward from the center of the gear 66A. The first shaft portion 66B is cylindrical. The first shaft portion 66B has a constant outer diameter in the vertical direction. The outer diameter of the first shaft portion 66B is referred to as a first diameter R1. The tapered portion 66C extends upward from the first shaft portion 66B, and the outer diameter decreases as it extends upward.

[0044] The second shaft portion 66D extends upward from the upper end of the tapered portion 66C. The second shaft portion 66D is cylindrical. The outer diameter of the second shaft portion 66D is constant in the vertical direction. The outer diameter of the second shaft portion 66D is referred to as the second diameter R2. The second diameter R2 of the second shaft portion 66D is smaller than the first diameter R1 of the first shaft portion 66B.

[0045] The second shaft portion 66D is provided with a hook 75. The hook 75 is arranged around the second shaft portion 66D. The hook 75 positions the drive cam 67 and prevents it from coming off.

[0046] The hook 75 has an extension 75A and a protrusion 75B. The extension 75A extends upward from the lower end of the second shaft portion 66D. The extension 75A is flexible in the radial direction of the shaft 65. The protrusion 75B protrudes radially outward from the upper end of the extension 75A. The protrusion 75B has a tapered surface 759. The tapered surface 759 slopes radially outward as it extends downward. When the drive cam 67 (described below) is attached to the shaft 65, the protrusion 75B is located above the upper end of the drive cam 67 and protrudes radially outward beyond the inner wall of the drive cam 67. The lower surface of the protrusion 75B contacts the upper end of the drive cam 67 from above.

[0047] Here, length L15 shown in Figure 9 is the radial length of the gap between the shaft 52 and the inner wall of the hook 75. Protrusion amount L17 is the amount by which the protrusion 75B protrudes radially outward beyond the inner wall of the drive cam 67. Protrusion amount L17 is greater than length L15. This allows the hook 75 to continue to abut against the drive cam 67 from above, even if, for example, the hook 75 bends toward the shaft 52. This prevents the drive cam 67 from coming loose.

[0048] The third shaft portion 66E extends upward from the upper end of the second shaft portion 66D. The third shaft portion 66E extends upward from the second shaft portion 66D. The third shaft portion 66E is cylindrical. The third shaft portion 66E has a constant outer diameter in the vertical direction. The outer diameter of the third shaft portion 66E is referred to as a third diameter R3. The third diameter R3 is smaller than the second diameter R2. The third shaft portion 66E is provided with a transmission gear 679 extending in the vertical direction. The third shaft portion 66E is inserted into an input gear 134 (see FIG. 11 ), which will be described later. The third shaft portion 66E transmits driving force from the motor 61 to the input gear 134 via the transmission gear 679.

[0049] The clutch spring 68 is a coil spring. The clutch spring 68 has a main body 68A, a first arm 68B, and a second arm 68C. The main body 68A is attached to the outer peripheral surface of the first shaft 66B of the drive gear 66. The main body 68A extends spirally in the vertical direction. When the main body 68A is not attached to the drive gear 66, it has an inner diameter R4 that is smaller than the first diameter R1 and larger than the second diameter R2. Note that the third diameter R3 of the third shaft 66E is smaller than the inner diameter R4 of the clutch spring 68 when the clutch spring 68 is not attached to the first shaft 66B.

[0050] The first arm 68B extends radially outward from the upper end of the main body 68A. The second arm 68C extends radially outward from the lower end of the main body 68A. Before being attached to the first shank 66B, the second arm 68C is spaced apart radially from the first arm 68B (see FIG. 6). Note that when the main body 68A is attached to the first shank 66B, the inner diameter R4 of the main body 68A before attachment expands to the first diameter R1. Therefore, the second arm 68C is closer radially to the first arm 68B than it was before being attached to the first shank 66B (see FIG. 5).

[0051] The drive cam 67 is attached to the shaft 65. The drive cam 67 is a cylindrical part. The drive cam 67 is made of, for example, a resin material different from that of the drive gear 66. In this case, the drive cam 67 is made of a resin material of a different type or grade than that of the drive gear 66. The drive cam 67 is inserted into a take-up spool 107 (see FIG. 11 ) of the tape cassette 100, which will be described later. The drive cam 67 transmits driving force from the motor 61 (see FIG. 3 ) to the take-up spool 107.

[0052] The drive cam 67 has a cam portion 67A and a spring accommodating portion 67B. The cam portion 67A is inserted into the take-up spool 107. The cam portion 67A is cylindrical and extends in the vertical direction. The cam portion 67A has an inner diameter R5. The inner diameter R5 of the cam portion 67A is larger than the second diameter R2 of the second shaft portion 66D. The cam portion 67A is disposed around the second shaft portion 66D. The cam portion 67A transmits the driving force transmitted from the drive gear 66 to the take-up spool 107 (see FIG. 11 ).

[0053] The spring accommodating portion 67B is provided at the lower end of the cam portion 67A. The spring accommodating portion 67B is arranged around the first shaft portion 66B. The spring accommodating portion 67B includes an upper wall 675 and a peripheral wall 676. The upper wall 675 extends radially outward from the lower end of the cam portion 67A. In other words, the upper wall 675 is disk-shaped, with a central portion that is perforated in the up-down direction. The upper wall 675 covers the clutch spring 68 from above (see FIG. 5). The peripheral wall 676 extends downward from the radially outer end of the upper wall 675. The upper wall 675 covers the clutch spring 68 from the radially outer side (see FIG. 5).

[0054] The peripheral wall 676 has a notch 67C formed in an upward direction from the lower end. The notch 67C includes a first portion 671 and a second portion 672. The first portion 671 has a circumferential length of a first length L11 (see FIG. 6). The second portion 672 extends upward from the circumferential center of the first portion 671. The second portion 672 has a circumferential length of a second length L13 (see FIG. 6). The second length L13 is shorter than the first length L11.

[0055] The second portion 672 is provided with a first wall 672A and a second wall 672B. The first wall 672A and the second wall 672B face each other in the circumferential direction. The first wall 672A includes an extending portion 673 and an abutting portion 674 (see FIG. 7). The extending portion 673 extends from its radially outer end toward the inside toward the second wall 672B. The abutting portion 674 extends radially from the radially inner end of the extending portion 673. In other words, the first wall 672A extends radially inward from one circumferential end.

[0056] The second wall 672B includes an extension portion 677 and an abutment portion 678. The extension portion 677 extends from its radially outer end toward the inside toward the first wall 672A. The abutment portion 678 extends radially from the radially inner end of the extension portion 677. In other words, the second wall 672B extends radially inward from the other circumferential end.

[0057] 7, the abutment portion 674 of the first wall 672A abuts against the first arm portion 68B from one circumferential side. The abutment portion 678 of the second wall 672B abuts against the first arm portion 68B from the other circumferential side. Therefore, the first arm portion 68B of the clutch spring 68 abuts against the second portion 672 and is positioned in the circumferential direction. In addition, the radially outer end of the first arm portion 68B of the clutch spring 68 is positioned more inward than the radially outer end of the second portion 672.

[0058] 8 , the second arm 68C of the clutch spring 68 is disposed inside the first portion 671. Therefore, the second arm 68C does not contact the first portion 671. In addition, the radially outer end of the second arm 68C is disposed more inward than the radially outer end of the first portion 671.

[0059] 10 and 11, the configuration of the tape cassette 100 will be described. The tape cassette 100 stores a tape 101. By replacing the tape cassette 100, it is possible to replenish the tape 101 and change the type of tape 101 (for example, size, color, material, etc.).

[0060] The tape cassette 100 includes a main case 120. The main case 120 houses the tape 101 and the ink ribbon 104. The main case 120 has a first case 121 and a second case 122. The first case 121 and the second case 122 are each cuboid-shaped. In other words, the external shape of the main case 120 when viewed from the top and bottom is rectangular. The main case 120 is inserted into the cassette loading section 10 with the first case 121 facing the bottom surface 11 of the recess of the cassette loading section 10 (see FIG. 2).

[0061] The tape cassette 100 includes a tape roll 102, a tape spool 103, a ribbon roll 105, a ribbon spool 106, a take-up spool 107, and a drive transmission mechanism 130. The tape roll 102 is formed by winding a strip-shaped tape 101, on which printing is performed, around an axis of the tape spool 103. The axis of the tape roll 102 is parallel to the up-down direction.

[0062] Two spacer films 111, 112 are arranged on the outer sides of the tape roll 102 in the vertical direction, sandwiching the tape roll 102. The spacer film 111 is arranged between the tape roll 102 and the second lid portion 180, and the spacer film 112 is arranged between the tape roll 102 and the second frame portion 170. The tape 101 pulled out from the tape roll 102 is guided by a first roller 113 and a second roller 114.

[0063] The tape spool 103 is rotatable about a rotation axis that is parallel to the vertical direction. The tape spool 103 rotates as the tape 101 is fed by the platen roller 82 of the printer 1. As a result, the tape spool 103 supplies the tape 101 to the head opening 123 (see FIG. 10 ). The rotation axis of the tape spool 103 coincides with the axis of the tape roll 102. A clutch spring (not shown) held by a clutch spring holder 115 applies rotational resistance to the tape spool 103.

[0064] The ribbon roll 105 is a strip-shaped ink ribbon 104 used for printing on the tape 101, wound around a ribbon spool 106 around an axis. The ink ribbon 104 is overlapped with the tape 101 at the head opening 123 and used for printing by the print head 71. The ink ribbon 104 used for printing is taken up onto a take-up spool 107. The ribbon roll 105 is located at a different position (specifically, below) than the tape roll 102 in the vertical direction. Furthermore, the ribbon roll 105 is located at the same position as the head opening 123 in the vertical direction.

[0065] The ribbon spool 106 is rotatable around its rotation axis, which is parallel to the vertical direction. The ribbon spool 106 rotates as the ink ribbon 104 is taken up by the take-up spool 107, thereby supplying the ink ribbon 104 to the print head 71. A clutch spring (not shown) held by a clutch spring holder 116 applies rotational resistance to the ribbon spool 106.

[0066] The take-up spool 107 is rotatable about its rotation axis. The rotation axis of the take-up spool 107 is parallel to the rotation axis of the ribbon spool 106. The take-up spool 107 is cylindrical and has a hollow portion defined by an inner circumferential surface 108. Spline teeth 109 are provided on the inner circumferential surface 108 of the take-up spool 107. The cam portion 67A of the drive cam 67 of the drive shaft 63 is connected to the spline teeth 109. The take-up spool 107 is rotated by the cam portion 67A and winds up the ink ribbon 104. A torsion spring 110 applies rotational resistance to the take-up spool 107. The torsion spring 110 is disposed between the take-up spool 107 and the first frame portion 160.

[0067] The drive transmission mechanism 130 transmits the drive force transmitted via the transmission gear 679 of the third shaft portion 66E of the drive shaft 63 to the platen roller 82. The drive transmission mechanism 130 has an input gear 134, an idle gear 137, and an output gear 131.

[0068] The input gear 134 indirectly engages with the output gear 131 via an idle gear 137 and transmits driving force to the output gear 131. The input gear 134 has a gear portion 135 and a spool portion 136. The spool portion 136 is a cylindrical internal gear with spline teeth on its inner circumferential surface. The gear portion 135 is an external gear that meshes with an upstream gear 138 of the idle gear 137. The spool portion 136 is fixed to the underside of the gear portion 135, and the third shaft portion 66E of the drive shaft 63 is inserted from below. The gear portion 135 rotates integrally with the spool portion 136 due to the driving force input to the spool portion 136 from the third shaft portion 66E. The rotational axis L2 of the input gear 134 is aligned with the rotational axis of the take-up spool 107 and is parallel to the rotational axis L1 of the output gear 131.

[0069] The rotation axis L2 of the input gear 134 overlaps with the hollow portion of the take-up spool 107 in the vertical direction. Therefore, when the tape cassette 100 is attached to the cassette attachment portion 10, the drive shaft 63 is inserted through the take-up spool 107 and the input gear 134 at the same time. As a result, the input gear 134 is rotated by the drive shaft 63 together with the take-up spool 107.

[0070] The idle gear 137 meshes with the input gear 134 and the output gear 131, and transmits the driving force input to the input gear 134 to the output gear 131. The idle gear 137 is a stepped gear in which an upstream gear 138 and a downstream gear 139 are arranged side by side on the same axis. The upstream gear 138 is an externally toothed spur gear that meshes with the input gear 134. The downstream gear 139 is an externally toothed helical gear that meshes with the output gear 131. The gear teeth of the downstream gear 139 are twisted in the opposite direction to those of the output gear 131. The diameter of the downstream gear 139 is smaller than the diameter of the upstream gear 138. Furthermore, the downstream gear 139 is arranged closer to the tape roll 102 in the vertical direction than the upstream gear 138.

[0071] A rotation axis L3 of the idle gear 137 is parallel to the rotation axis L1 of the output gear 131 and the rotation axis L2 of the input gear 134. The idle gear 137 reduces the rotational speed of the driving force input to the input gear 134 and transmits it to the output gear 131. In other words, the drive transmission mechanism 130 includes a reduction mechanism.

[0072] The output gear 131 is an externally toothed gear. The output gear 131 meshes with the platen gear 83 to transmit a driving force for feeding the tape 101 to the platen gear 83. The output gear 131 is a helical gear whose gear teeth are twisted at a predetermined angle with respect to the rotation axis L1. The rotation axis L1 of the output gear 131 is parallel to the rotation axis L2 of the input gear 134 and the rotation axis L4 of the platen gear 83.

[0073] A portion of the output gear 131 is exposed to the space communicating with the head opening 123. When the tape cassette 100 is attached to the cassette attachment portion 10, the output gear 131 meshes with the platen gear 83 in the space communicating with the head opening 123.

[0074] The specifications of the output gear 131, the gear portion 135 of the input gear 134, and the upstream gear 138 and downstream gear 139 of the idle gear 137 (step gear) are as shown in Fig. 16. The individual elements of the specifications of the output gear 131, input gear 134, and idle gear 137 (step gear) listed in the table of Fig. 16 may be changed as appropriate, as long as the combination is compatible with the drive transmission mechanism 130 as a whole.

[0075] The printing operation of the printer 1 will now be described. When printing is to be performed, the tape cassette 100 is loaded into the cassette loading section 10. In this case, the print head 71 is positioned in the head opening 123 so that it vertically overlaps the tape 101 and ink ribbon 104. The drive cam 67 of the drive shaft 63 is inserted into the take-up spool 107. Furthermore, the third shaft portion 66E of the drive shaft 63 is inserted into the input gear 134. The platen roller 82 moves to the adjacent position. This causes the platen gear 83 to mesh with the output gear 131.

[0076] With the tape cassette 100 installed, the input gear 134 is rotated by the third shaft portion 66E of the drive shaft 63. This rotates the output gear 131 via the idle gear 137. Furthermore, the rotation of the output gear 131 rotates the platen gear 83, which in turn rotates the platen roller 82. The tape 101 is transported to the head opening 123 by the platen roller 82.

[0077] Meanwhile, the rotation of the gear 66A of the drive gear 66 causes the shaft 65 to rotate. In this case, the clutch spring 68 reduces the diameter of the main body portion 68A due to friction with the first shaft portion 66B. This increases the torque of the clutch spring 68. The clutch spring 68 transmits the driving force from the drive gear 66 to the drive cam 67 via the first arm portion 68B and the second portion 672. The drive cam 67 is imparted with the torque of the clutch spring 68. The drive cam 67 rotates due to the transmitted driving force. As the drive cam 67 rotates, the cam portion 67A rotates the take-up spool 107. This unwinds the ink ribbon 104 from the ribbon roll 105. The ink ribbon 104 is transported toward the head opening 123.

[0078] At the head opening 123, the tape 101 is pressed against the print head 71 via the ink ribbon 104 by the platen roller 82. The print head 71 selectively heats the heating elements 71A. This causes a portion of the ink disposed on the surface of the ink ribbon 104 to be transferred to the tape 101, printing characters, symbols, etc. on the tape 101. The platen roller 82 transports the printed tape 101 from the tape cassette 100 toward the discharge path 29. The used ink ribbon 104 is taken up onto the take-up spool 107.

[0079] 12 to 14, the positioning of the print head 71 and platen roller 82 during the manufacturing process of the printer 1 will be described. As shown in Figure 12, an operator uses a jig 140 to position the print head 71. The jig 140 is a rectangular parallelepiped that extends in the left-right direction. The operator abuts the jig 140 against the left end of the mounting portion 141 from behind.

[0080] The worker places the heat sink 72 on the base 51. The pins 51A and 51B of the base 51 are inserted into the holes 72A and 72B, respectively, of the lower end 72F of the heat sink 72. Because the holes 72A and 72B are long in the front-to-rear direction, the heat sink 72 can move in the front-to-rear direction relative to the base 51.

[0081] The worker brings the front end of the right end 72U of the heat sink 72 into contact with the rear surface of the jig 140 from behind. This positions the heat sink 72 in the front-to-rear direction. In this state, the worker secures the heat sink 72 to the base 51 with screws 51C. Therefore, the print head 71 is positioned relative to the platen roller 82, which is in the proximity position.

[0082] As shown in Figures 13 and 14, the operator can also position the heat sink 72, and therefore the print head 71, based on the position of the platen roller 82. The operator moves the platen roller 82 to the proximity position. When the platen roller 82 is in the proximity position, the notch 82E faces right. The operator uses the position of the notch 82E as a guide to position the heating elements 71A of the print head 71. In this case, the front-to-rear center C1 of the platen roller 82 is positioned a distance L5 forward of the front-to-rear center C2 of the heating elements 71A. In this state, the operator secures the heat sink 72 to the base 51 with screws 51C. Therefore, the print head 71 is positioned relative to the platen roller 82 in the proximity position.

[0083] 15, the procedure for assembling the drive shaft 63 during the assembly of the printing unit 50 will be described. During manufacturing, the worker inserts the clutch spring 68 into the second shaft portion 66D (see FIG. 15A). In this case, the clutch spring 68 is inserted up to the periphery of the tapered portion 66C, for example.

[0084] After that, the operator attaches the drive cam 67 to the shaft 65 of the drive gear 66 from above (see FIGS. 15A and 15B). The drive cam 67 is guided downward by the tapered surface 759 of the hook 75. Furthermore, the extension 75A of the hook 75 bends radially inward when the drive cam 67 is attached to the shaft 65. Therefore, the drive cam 67 moves smoothly downward relative to the shaft 65.

[0085] The worker brings the spring accommodating portion 67B of the drive cam 67 into contact with the clutch spring 68 (see FIG. 15B). In this case, the upper wall 675 of the spring accommodating portion 67B comes into contact with the main body portion 68A of the clutch spring 68 from above. The worker places the first arm portion 68B of the clutch spring 68 against the second portion 672 of the spring accommodating portion 67B. The worker can easily perform the work because he or she can see the clutch spring 68 through the notch 67C.

[0086] The operator further moves the drive cam 67 downward relative to the shaft 65 (see FIGS. 15B and 15C). In this case, the spring accommodating portion 67B of the drive gear 66 abuts against the clutch spring 68 and moves downward. The clutch spring 68 moves toward the first shaft portion 66B via the tapered portion 66C while expanding its inner diameter R4. In this case, the second arm portion 68C of the clutch spring 68 moves toward the first arm portion 68B. When the clutch spring 68 is attached to the drive gear 66, the clutch spring 68 is attached to the first shaft portion 66B.

[0087] The drive gear 66 is prevented from coming off the shaft 65 by a hook 75 (see FIG. 15C). The first arm 68B of the clutch spring 68 is positioned in the second part 672 of the spring accommodating part 67B. The second arm 68C of the clutch spring 68 is disposed in the first part 671 of the spring accommodating part 67B.

[0088] As described above, the shaft 65 includes a first shaft portion 66B, a tapered portion 66C, and a second shaft portion 66D. The first shaft portion 66B extends upward from the gear 66A and has a clutch spring 68 attached thereto. The tapered portion 66C extends upward from the upper end of the first shaft portion 66B, and its outer diameter decreases as it extends upward. The second shaft portion 66D extends upward from the upper end of the tapered portion 66C. The second diameter R2, which is the maximum outer diameter of the second shaft portion 66D, is smaller than the first diameter R1, which is the maximum outer diameter of the first shaft portion 66B. When not attached to the first shaft portion 66B, the clutch spring 68 has an inner diameter R4 that is smaller than the first diameter R1 and larger than the second diameter R2. The drive cam 67 is provided with a spring housing 67B. The spring housing 67B opens downward and houses the clutch spring 68.

[0089] In the printer 1 described above, the inner diameter R4 of the clutch spring 68 is smaller than the first diameter R1 of the first shaft portion 66B and larger than the second diameter R2. During manufacturing, an operator inserts the clutch spring 68 onto the second shaft portion 66D. In this case, the clutch spring 68 is inserted, for example, up to the area around the tapered portion 66C. The operator then attaches the drive cam 67 to the shaft 65 of the drive gear 66 from above. In this case, the spring accommodating portion 67B of the drive gear 66 abuts against the clutch spring 68 and moves downward. The clutch spring 68 moves toward the first shaft portion 66B via the tapered portion 66C while expanding its inner diameter R4. When the clutch spring 68 is attached to the drive gear 66, the clutch spring 68 is attached to the first shaft portion 66B. Therefore, the printer 1 allows for easy attachment of the clutch spring 68 to the drive gear 66.

[0090] During the process of attaching the drive cam 67 to the shaft 65, the spring accommodating portion 67B abuts against the clutch spring 68 from above and moves it downward, thereby attaching the clutch spring 68 to the first shaft portion 66B. Therefore, the printer 1 can easily attach the clutch spring 68 to the drive gear 66.

[0091] A hook 75 is provided on the second shaft portion 66D. The hook 75 has an extension portion 75A and a protrusion portion 75B. The extension portion 75A extends in the vertical direction. The protrusion portion 75B protrudes radially outward from the upper end of the extension portion 75A of the shaft 65. When the drive cam 67 is attached to the shaft 65, the protrusion portion 75B is located above the upper end of the drive cam 67 and protrudes radially outward from the inner wall of the drive cam 67. In the printer 1, the vertical position of the drive cam 67 relative to the drive gear 66 is fixed.

[0092] The extensions 75A are flexible and bend radially inward when the drive cam 67 is attached to the shaft 65. When the drive cam 67 is attached to the shaft 65, the hooks 75 bend radially inward. Therefore, the hooks 75 do not interfere with the attachment of the drive cam 67 to the shaft 65.

[0093] The protrusion 75B has a tapered surface 759 that slopes radially outward as it extends downward. When the drive cam 67 is attached to the shaft 65, the tapered surface 759 can smoothly guide the drive cam 67 downward.

[0094] The shaft 65 is cylindrical and is inserted through the shaft 52 provided in the cassette loading section 10. The drive cam 67 is inserted through the shaft 65. The radial length L15 of the gap between the shaft 52 and the inner wall of the hook 75 is greater than the radial length L17 of the protruding portion 75B projecting radially outward from the inner wall of the drive cam 67. In the printer 1, even if the hook 75 bends radially inward while the drive cam 67 is attached to the shaft 65, the hook 75 continues to engage with the drive cam 67. Therefore, the printer 1 can more reliably prevent the drive cam 67 from coming off the shaft 65.

[0095] The clutch spring 68 includes a main body 68A, a first arm 68B, and a second arm 68C. The main body 68A extends spirally in the vertical direction. The first arm 68B extends from the upper end of the main body 68A radially outward from the shaft 65. The second arm 68C extends from the lower end of the main body 68A radially outward from the shaft 65. The clutch spring 68 has a shape that is symmetrical in the vertical direction. Because the shape of the clutch spring 68 is symmetrical in the vertical direction, an operator can insert the clutch spring 68 onto the shaft 65 without making a mistake in the orientation of the clutch spring 68.

[0096] The spring accommodating portion 67B includes an upper wall 675 and a peripheral wall 676. The upper wall 675 is disk-shaped and covers the clutch spring 68 from above. The peripheral wall 676 extends downward from the radially outer end of the upper wall 675 and covers the clutch spring 68 from the radially outer side. A notch 67C is formed in the peripheral wall 676 and faces upward from the lower end of the peripheral wall 676. The notch 67C includes a first portion 671 and a second portion 672. The first portion 671 has a circumferential length of a first length L11. The second portion 672 extends upward from the circumferential center of the first portion 671 and has a circumferential length of a second length L13 that is shorter than the first length L11. The first arm portion 68B abuts against the second portion 672 and is positioned circumferentially. The second arm portion 68C is disposed in the first portion 671. The position of the second arm 68C of the clutch spring 68 relative to the first arm 68B varies due to dimensional errors. Because the first length L11 of the first portion 671 is longer than the second length L13 of the second portion 672, the second arm 68C of the clutch spring 68 fits within the first portion 671. Furthermore, even if there is variation due to dimensional errors, the second arm 68C of the clutch spring 68 does not abut against the first portion 671. Therefore, the torque of the clutch spring 68 is appropriately applied to the drive cam 67.

[0097] The second portion 672 is provided with a first wall 672A and a second wall 672B. The first wall 672A extends radially inward from an end portion on one side in the circumferential direction. The second wall 672B extends radially inward from an end portion on the other side in the circumferential direction. The first wall 672A abuts against the first arm portion 68B from one side in the circumferential direction. The second wall 672B abuts against the first arm portion 68B from the other side in the circumferential direction. The first wall 672A and the second wall 672B allow the second portion 672 to abut against the first arm portion 68B more reliably.

[0098] The radially outer end of the first arm 68B is positioned radially inward of the second portion 672. The radially outer end of the second arm 68C is positioned radially inward of the first portion 671. In the printer 1, the clutch spring 68 is accommodated inside the spring accommodating portion 67B. This reduces the possibility that an operator or a user of the printer 1 will come into contact with the clutch spring 68.

[0099] The drive gear 66 includes a third shaft portion 66E. The third shaft portion 66E has a third diameter R3. The third diameter R3 is smaller than the inner diameter R4 of the clutch spring 68 when the clutch spring 68 is not attached to the first shaft portion 66B. The third shaft portion 66E extends upward from the second shaft portion 66D. A transmission gear 679 is provided on the third shaft portion 66E. The transmission gear 679 transmits driving force to the tape cassette 100. When it is necessary to transmit driving force to the tape cassette 100, the drive gear 66 requires a larger torque. Therefore, the diameter of the clutch spring 68 needs to be smaller. Even in such a case, the operator can easily attach the clutch spring 68 to the drive gear 66. Furthermore, since the third shaft portion 66E is located above the second shaft portion 66D, the shaft 65 becomes longer in the upward direction. Even in this case, since the third diameter R3 of the third shaft portion 66E is smaller than the inner diameter R4 of the clutch spring 68, the clutch spring 68 can be smoothly moved to the first shaft portion 66B.

[0100] The drive gear 66 and the drive cam 67 are made of different materials. If the drive cam 67 and the drive gear 66 were made of the same material, resonance would easily occur during friction, and the sliding load would be unstable. This would cause the torque to be unstable when the ink ribbon 104 is wound up. By combining a drive gear 66 and a drive cam 67 made of different materials, it is possible to stabilize the torque when the ink ribbon 104 is wound up.

[0101] In the above embodiment, the cassette loading section 10 is an example of the "loading section" of the present invention. The tape cassette 100 is an example of the "cassette" of the present invention. The motor 61 is an example of the "drive source" of the present invention.

[0102] The present invention can be modified from the above embodiment. In the above embodiment, the drive shaft 63 is applied to the take-up spool 107 of the ink ribbon 104, but this is not limiting. The drive shaft 63 may be applied to rotational drive of a spool other than the take-up spool 107 of the ink ribbon 104.

[0103] In the above embodiment, the shaft 65 is cylindrical, but this is not limiting. For example, the internal shape of the shaft 65 may be a shape other than cylindrical. For example, it may be polygonal. Furthermore, the length of the shaft 65 may be changed as appropriate. The shapes and lengths of the first shaft portion 66B, the second shaft portion 66D, and the third shaft portion 66E may be changed as appropriate. The shapes of the shaft 52, the take-up spool 107, the input gear 134, etc. may be changed accordingly.

[0104] In the above embodiment, the outer diameter of the first shaft portion 66B is constant in the vertical direction, but this is not limited to this. For example, the first diameter R1 of the first shaft portion 66B does not have to be constant. The same applies to the second diameter R2 of the second shaft portion 66D and the third diameter R3 of the third shaft portion 66E. It is sufficient that the relationship between the size of the first diameter R1, the second diameter R2, the third diameter R3, and the inner diameter R4 is maintained.

[0105] In the above embodiment, the drive cam 67 is cylindrical, but the shape of the drive cam 67 is not limited to this. The shape of the drive cam 67 may be changed as appropriate.

[0106] In the above embodiment, the hook 75 has the tapered surface 759 on the protruding portion 75B, but this is not limiting. The tapered surface 759 may be omitted as long as it does not interfere with the attachment of the drive cam 67 to the shaft 65.

[0107] In the above embodiment, the clutch spring 68 has a shape that is symmetrical in the vertical direction, but this is not limiting. The shape and dimensions of the clutch spring 68 may be changed as appropriate as long as the clutch spring 68 can be appropriately attached to the first shaft portion 66B and can apply torque to the drive cam 67.

[0108] In the above embodiment, the notch 67C allows the clutch spring 68 to be visible, but this is not limiting. For example, the clutch spring 68 may not be visible. For example, a groove corresponding to the notch 67C may be provided on the inner side of the peripheral wall 676, and the first arm 68B and the second arm 68C may be disposed in that portion.

[0109] Although the drive gear 66 in the above embodiment is provided with the third shaft portion 66E, this is not limiting. For example, the drive gear 66 does not have to be provided with the third shaft portion 66E. In this case, the transmission of the driving force to the platen gear 83 may be realized by a separate mechanism.

[0110] In the above embodiment, the tape cassette 100 is a receptor type that transfers the ink of the ink ribbon 104 onto the surface of the tape 101, but this is not limited to this and the cassette may be capable of printing on various types of tape, such as double-sided adhesive tape, film tape, and laminated tape.

[0111] In the above embodiment, the drive gear 66 and the drive cam 67 are made of a resin material, but this is not limiting. For example, the drive gear 66 and the drive cam 67 may be made of a material other than a resin material, such as a metal. As long as the torque during winding of the ink ribbon 104 can be stabilized, the drive gear 66 and the drive cam 67 may be made of any material combination.

[0112] 1 Printer 10 Cassette mounting section 52 Shaft 62 Gear group 65 Shaft 66B First shaft section 66C Tapered section 66D Second shaft section 66E Third shaft section 67 Drive cam 67B Spring accommodating section 68 Clutch spring 68A Main body section 68B First arm section 68C Second arm section 75 Hook 75A Extension section 75B Protrusion section 100 Tape cassette 675 Upper wall 676 Peripheral wall 671 First section 672 Second section 672A First wall 672B Second wall 759 Tapered surface R1, R2, R3, R4 Diameter L15, L17 Length

Claims

1. A printing device comprising: a mounting section capable of mounting a cassette having an ink ribbon used for printing and a take-up spool for taking up the ink ribbon; a drive gear having a gear that rotates by the driving force of a drive source and a shaft that rotates together with the gear, extending upward from the gear and exposed to the mounting section; an annular clutch spring mounted on the shaft; and a drive cam that is a cylindrical cam mounted on the shaft and capable of engaging with the take-up spool on its outer surface, the drive cam being rotated by torque applied from the clutch spring as the shaft rotates, thereby rotating the take-up spool; the shaft comprising: a first shaft section that extends upward from the gear and on which the clutch spring is mounted; a tapered section that extends upward from the upper end of the first shaft section and whose outer diameter becomes smaller as it extends upward; and a second shaft section that extends upward from the upper end of the tapered section, wherein a second diameter that is the maximum outer diameter of the second shaft section is smaller than a first diameter that is the maximum outer diameter of the first shaft section, the clutch spring has an inner diameter smaller than the first diameter and larger than the second diameter when not attached to the first shaft portion, and the drive cam is provided with a spring accommodating portion that opens downward and accommodates the clutch spring.

2. The printer described in claim 1, characterized in that, during the process of attaching the drive cam to the shaft, the spring accommodating portion abuts the clutch spring from above and moves it downward, thereby attaching the clutch spring to the first shaft portion.

3. The printer described in claim 1, characterized in that a hook is provided on the second shaft portion, the hook having an extension portion extending in the vertical direction and a protrusion portion protruding from the upper end of the extension portion radially outward from the shaft, the protrusion portion being positioned above the upper end of the drive cam when the drive cam is attached to the shaft, and protruding radially outward from the inner wall of the drive cam.

4. The printer according to claim 3, wherein the extension portion is flexible and bends radially inward when the drive cam is attached to the shaft.

5. The printer according to claim 4, wherein the protrusion has a tapered surface that slopes outward in the radial direction as it extends downward.

6. The printer described in claim 4, characterized in that the axle is cylindrical and is inserted into a shaft provided in the mounting portion, the drive cam is inserted into the axle, and the amount by which the protruding portion protrudes radially outward beyond the inner wall of the drive cam is greater than the radial length of the gap between the shaft and the inner wall of the hook.

7. The printer described in claim 1, characterized in that the clutch spring comprises a main body portion extending spirally in the vertical direction, a first arm portion extending from the upper end of the main body portion radially outward from the shaft, and a second arm portion extending from the lower end of the main body portion radially outward, and the clutch spring has a symmetrical shape in the vertical direction.

8. The printer described in claim 7, wherein the spring accommodating section comprises: a disk-shaped upper wall that covers the clutch spring from above; and a peripheral wall that extends downward from the radially outer end of the upper wall and covers the clutch spring from the radially outer side; a notch that faces upward from the lower end of the peripheral wall is formed in the peripheral wall; the notch has: a first portion having a first circumferential length; and a second portion that extends upward from the circumferential center of the first portion and has a circumferential length that is shorter than the first length; the first arm abuts on the second portion and is positioned in the circumferential direction; and the second arm is disposed on the first portion.

9. The printer described in claim 8, characterized in that the second portion is provided with a first wall extending radially inward from an end portion on one side in the circumferential direction, and a second wall extending radially inward from an end portion on the other side in the circumferential direction, the first wall abutting against the first arm portion from one side in the circumferential direction, and the second wall abutting against the first arm portion from the other side in the circumferential direction.

10. A printer as described in claim 9, characterized in that the radially outer end of the first arm is positioned more inward than the second portion in the radial direction, and the radially outer end of the second arm is positioned more inward than the first portion in the radial direction.

11. The printer described in claim 1, characterized in that the drive gear further comprises a third shaft portion extending upward from the second shaft portion and having a third diameter smaller than the inner diameter of the clutch spring when the clutch spring is not attached to the first shaft portion, and a transmission gear is provided on the third shaft portion to transmit the driving force to the cassette.

12. The printer according to claim 1, wherein the drive gear and the drive cam are made of different materials.

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