Printing unit and thermal printer

Abstract

To provide a printing unit and a thermal printer with a drive mechanism and a return mechanism that respectively enable design with a high degree of freedom.SOLUTION: A printing unit includes: a fixed blade disposed in one of a head unit and a platen unit; a movable blade provided in the other of the head unit and the platen unit and movable relative to the fixed blade; and a rack member 300 connected to the movable blade and movable integrally with the movable blade. The rack member 300 comprises: a drive rack 71 including a plurality of drive rack teeth 71a meshing with the drive pinion 78; and a return rack 130 formed independently of the drive rack 71 and having a plurality of return rack teeth 130a meshing with a return pinion 131.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] The present invention relates to a printing unit and a thermal printer. [Background technology]

[0002] For example, a thermal printer is equipped with a printing unit. The printing unit is a unit that cuts paper between a movable blade and a fixed blade by moving the movable blade from a standby position to a cutting position. When the movable blade is moved to the cutting position to cut the paper, a paper jam (i.e., a paper jam) may occur between the movable blade and the fixed blade, and the movable blade may stop at a position where it rides up over the fixed blade.

[0003] Patent Document 1 discloses a configuration including a drive mechanism for moving the movable blade, an operating lever for a platen unit, and a return mechanism for the movable blade. In this configuration, the drive mechanism has a drive rack connected to the movable blade, and moves the movable blade between a standby position away from the fixed blade and a cutting position where the movable blade is placed on the fixed blade. The operating lever is movable between a lock position where the platen unit is locked and an unlock position where the platen unit is unlocked. When the movable blade is stopped at the cutting position, the return mechanism moves the movable blade from the cutting position to the standby position via the drive rack in conjunction with the operating lever. In Patent Document 1, when the movable blade is stopped at the cutting position, such a return mechanism transmits power associated with the operation of the operating lever from the lock position toward the unlock position to the drive mechanism, and moves the movable blade toward the standby position. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-108945 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the configuration disclosed in Patent Document 1, the pinion gear of the drive mechanism for moving the movable blade and the pinion gear of the return mechanism for returning the movable blade to the standby position are engaged with the same drive rack. Therefore, the pinion gear of the drive mechanism and the pinion gear of the return mechanism are driven in the same phase. In other words, the operation of the drive mechanism and the operation of the return mechanism are synchronized. For this reason, there are restrictions on optimally designing the drive mechanism and the return mechanism, respectively. SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a printing unit and a thermal printer in which the drive mechanism and the return mechanism can each be designed with a high degree of freedom. [Means for solving the problem]

[0006] In order to achieve the above object, a printing unit according to one aspect of the present invention comprises a head unit having a thermal head that prints on recording paper, a platen unit having a platen roller that transports the recording paper and that is separably combined with the head unit, a fixed blade provided on one of the head unit and the platen unit, and a movable blade provided on the other of the head unit and the platen unit and that is movable relatively to the fixed blade, the other unit comprising a rack member that is connected to the movable blade and that is movable integrally with the movable blade. the movable blade is provided with a drive mechanism having a drive pinion that meshes with the rack member and moves the movable blade between a standby position away from the fixed blade and a cutting position where the movable blade rides on the fixed blade; and a return mechanism having a return pinion that meshes with the rack member and moves the movable blade from the cutting position toward the standby position when the movable blade is stopped at the cutting position, wherein the rack member comprises a drive rack having a plurality of drive rack teeth that mesh with the drive pinion, and a return rack that is formed independently of the drive rack and has a plurality of return rack teeth that mesh with the return pinion.

[0007] According to this configuration, when the drive pinion is rotated by the drive mechanism, the movable blade moves between the standby position and the cutting position together with the rack member that meshes with the drive pinion. The movable blade rides up on the fixed blade at the cutting position, cutting the recording paper. After cutting the recording paper, the movable blade returns from the cutting position to the standby position. If the movable blade stops at the cutting position due to a paper jam that occurs between the fixed blade and the movable blade at the cutting position, the return mechanism rotates the return pinion, thereby moving the return rack that meshes with the return pinion and moving the movable blade together with the rack member from the cutting position to the standby position. In such a configuration, the drive rack and the return rack are formed separately and independently. Therefore, the drive rack can be designed to be suitable for moving the movable blade with the drive mechanism without considering the operation when the movable blade is returned by the return mechanism. In addition, the return rack can be designed to be suitable for returning the movable blade with the return mechanism without considering the operation when the movable blade is moved by the drive mechanism. In this way, the drive mechanism and the drive mechanism and return mechanism can each be designed with a high degree of freedom.

[0008] In a printing unit according to one embodiment of the present invention, the drive rack and the return rack are arranged in parallel, and the drive rack teeth of the drive rack and the return rack teeth of the return rack may have at least one of a phase and a pitch that are different from each other.

[0009] According to this configuration, by making at least one of the phase and pitch different between the drive rack teeth and the return rack teeth, it is possible to make the operation of the drive mechanism and the return mechanism different. Therefore, it is possible to make the operation of the drive mechanism and the return mechanism different without making the positions of the drive rack teeth and the return rack teeth different in the radial direction of the drive pinion and the return pinion that mesh with the drive rack teeth and the return rack teeth. Therefore, it is difficult to change the layout of the peripheral parts of the drive rack teeth and the return rack teeth, and design can be easily performed.

[0010] In one aspect of the present invention, a printing unit may include an operating lever that is rotatable between a locking position that locks the platen unit relative to the head unit and an unlocking position that unlocks the platen unit relative to the head unit, and a return gear that is rotatable in conjunction with the rotation of the operating lever and has a plurality of gear teeth that can mesh with the return pinion.

[0011] According to this configuration, when the operating lever is rotated between the locked position and the unlocked position, the return gear rotates in accordance with the rotation of the operating lever. By meshing multiple gear teeth of the return gear with the return pinion, the rotation of the return gear can be transmitted to the return rack via the return pinion. As a result, by operating the operating lever, the return rack can be moved and the movable blade can be moved from the cutting position to the standby position.

[0012] In the printing unit according to one aspect of the present invention, the plurality of gear teeth may be formed over a range covering a portion of the circumferential direction of the return gear.

[0013] According to this configuration, the return rack can be moved only while the multiple gear teeth formed over a portion of the circumferential range of the return gear are engaged with the return pinion by rotating the operating lever. In other words, when the multiple gear teeth are not engaged with the return pinion, the return pinion does not rotate and the return rack does not move. This makes it possible to appropriately set the timing for moving the return rack according to the rotation angle of the operating lever.

[0014] In a printing unit according to one embodiment of the present invention, the return rack teeth of the return rack may be formed so that, when the movable blade is in the cutting position, the return pinion meshes with the gear tooth portion among the multiple gear tooth portions that is located furthest forward in the rotational direction of the return gear, which rotates in conjunction with the rotation of the operating lever by operating the operating lever from the locked position toward the unlocked position.

[0015] According to this configuration, when the movable blade is in the cutting position, the return rack teeth of the return rack mesh with the return pinion, which among the multiple gear teeth, is located furthest forward in the rotation direction of the return pinion that rotates with the rotation of the operating lever by operating the operating lever from the locked position to the unlocked position. This makes it possible to unify the timing at which the gear teeth located furthest forward in the rotation direction of the return pinion mesh with the return pinion when the operating lever is rotated while the cutting teeth are in the cutting position. This makes it possible to stabilize the timing and amount of movement of the return rack when the operating lever is rotated, and to reliably return the movable blade from the cutting position to the standby position.

[0016] The thermal printer of the present invention comprises a printing unit as described above, a printer body having a recording paper storage section for storing the recording paper, and having one of the head unit and the platen unit attached thereto, and a printer cover that is rotatably connected to the printer body and has the other of the head unit and the platen unit attached thereto.

[0017] According to this configuration, it is possible to provide a thermal printer equipped with a printing unit in which the drive mechanism and the return mechanism can each be designed with a high degree of freedom. Effect of the Invention

[0018] According to one aspect of the present invention, the drive mechanism and the return mechanism can each be designed with a high degree of freedom. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view of a thermal printer according to an embodiment of the present invention, showing a state in which a printer cover is closed. [Diagram 2] 2 is a perspective view of the thermal printer shown in FIG. 1 with the printer cover open. [Diagram 3]FIG. 3 is a perspective view of the printing unit shown in FIG. 2. [Figure 4] 4 is a perspective view of the printing unit with a gear cover and the like removed from the state shown in FIG. 3. [Diagram 5] 5 is a perspective view of the printing unit shown in FIG. 4 with the platen frame and the like removed. [Figure 6] FIG. 5 is a perspective view of the platen unit shown in FIG. [Figure 7] 6 is a side view seen from the direction of the arrow A shown in FIG. 5, illustrating the relationship between the accommodating groove and the platen bearing. [Figure 8] 4 is a perspective view showing a state in which the recording paper is cut between the fixed blade and the movable blade. FIG. [Figure 9] FIG. 6 is a side view seen from the direction of arrow A shown in FIG. 5. [Figure 10] FIG. 10 is a perspective view of each mechanism shown in FIG. 9. [Figure 11] FIG. 4 is a perspective view showing a rack member. [Figure 12] FIG. 2 is a perspective view showing a rack member, a drive pinion, and a return pinion. [Figure 13] 10 is a side view showing a state in which a return gear and the like have been removed from the state shown in FIG. 9. FIG. [Figure 14] 13 is a perspective view of the operating lever and the periphery of the return mechanism as viewed from the opposite side. FIG. [Figure 15] FIG. [Figure 16] 14 is a perspective view showing a state in which the operating lever is removed from the state shown in FIG. 13. [Figure 17] 4 is a perspective view of the periphery of the operating lever as viewed from the opposite side. FIG. [Figure 18] 10 is a side view showing a state in which the operating lever has been pressed down from the lock position from the state shown in FIG. 9. FIG. [Figure 19] FIG. 13 is a diagram showing a state in which the return gear meshes with the return pinion. [Figure 20] FIG. 13 is a diagram showing a first state in which the return gear meshes with the return pinion when the drive rack and the return rack are in phase for comparison. [Figure 21] FIG. 13 is a diagram showing a second state in which the return gear meshes with the return pinion when the drive rack and the return rack are in phase for comparison. [Figure 22] 19 is a side view showing a state in which the operating lever has been further depressed from the state shown in FIG. 18. FIG. [Diagram 23] 23 is a side view showing a state in which the operating lever is further pressed down from the state shown in FIG. 22 until the abutment surface of the operating lever abuts against the boss of the detachment arm. FIG. [Figure 24] 24 is a side view showing a state in which the operating lever has been further depressed from the state shown in FIG. 23 to be positioned at the unlocked position, and the platen bearing has been pushed up to the open mouth of the accommodation groove. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A printing unit and a thermal printer according to the present invention will now be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiment. As shown in FIGS. 1 and 2, a thermal printer 1 is a printer that can print on rolled recording paper (thermal paper) P and use the recording paper P as, for example, tickets, receipts, and the like.

[0021] The thermal printer 1 is installed, for example, at a store front, and its operation is controlled by an information processing device (not shown). Therefore, the thermal printer 1 is controlled so as to print various information transmitted from the information processing device onto recording paper P and to eject the printed recording paper P.

[0022] The thermal printer 1 is installed, for example, on a mounting surface S in a storefront, and is formed into a cube shape as a whole. In this embodiment, in the state shown in Figures 1 and 2, the direction perpendicular to the mounting surface S is called the up-down direction L1, and the directions perpendicular to each other in a plane parallel to the mounting surface S are called the front-rear direction (second direction) L2 and the left-right direction (first direction) L3. In the front-rear direction L2, the front is indicated by an arrow FW, and the rear is indicated by an arrow BK. Therefore, in Figures 1 and 2, the lower left side of the paper is the front FW, and the upper right side is the rear BK.

[0023] The thermal printer 1 comprises a casing (printer body according to the present invention) 2, a printer cover 3, and a printing unit 4 consisting of a head unit 5 and a platen unit 6, and is a so-called front-feed type in which recording paper P is discharged forward FW. In the illustrated example, the platen unit 6 is provided on the printer cover 3 side, and the head unit 5 is provided on the casing 2 side. However, the present invention is not limited to this case. For example, the head unit 5 may be provided on the printer cover 3 side, and the platen unit 6 may be provided on the casing 2 side.

[0024] (Casing) The casing 2 is made of a synthetic resin material, a metal material, or a suitable combination of these, and is formed into a cube shape having an opening in the front FW, and has a plurality of outer surfaces 10 including a bottom surface 11 that faces the installation surface S. However, the shape of the casing 2 is not limited to this case, and may be changed as appropriate.

[0025] Of the multiple outer surfaces 10, the outer surface facing the bottom surface 11 in the up-down direction L1 is called a top surface 12. Of the multiple outer surfaces 10, the outer surface located on the forward FW side is called a front surface 13, and the outer surface located on the rear BK side is called a rear surface 14. These front surface 13 and rear surface 14 face each other in the forward-backward direction L2. Furthermore, of the multiple outer surfaces 10, the outer surfaces facing each other in the left-right direction L3 are called a pair of side surfaces 15.

[0026] A recording paper storage section 16 capable of storing rolled recording paper P is formed inside the casing 2 through an opening formed in the front surface 13 of the casing 2. This makes it possible to insert the rolled recording paper P into the recording paper storage section 16 from the front FW when the printer cover 3 is open.

[0027] The printer cover 3 is connected to the lower part of the front surface 13 of the casing 2 via a rotating shaft 17, and closes the opening in an openable manner. The printer cover 3 is connected so as to be rotatable around the rotating shaft 17 within an angular range of approximately 90 degrees. 1, when the printer cover 3 is closed, a small gap is designed to be formed between the tip of the printer cover 3 and the casing 2. This gap is used to pull the recording paper P out from inside the casing 2 to the front FW and eject it. Therefore, this gap functions as an ejection port 18 for the recording paper P.

[0028] When the printer cover 3 is closed, the casing 2 and printer cover 3 configured as described above are locked in conjunction with the combination of the platen unit 6 and the head unit 5. This causes the printer cover 3 to be locked in the closed state.

[0029] Furthermore, as shown in Fig. 1, the casing 2 is provided with a lever 19 for releasing the combination (lock) of the platen unit 6 and the head unit 5 at a corner where the front surface 13, the top surface 12, and one of the side surfaces 15 intersect. This also releases the lock of the printer cover 3 as shown in Fig. 2, making it possible to open the printer cover 3. The lever 19 can be operated by pressing it downward, for example.

[0030] The printer cover 3 is provided with operation buttons 3a, such as a power button and a paper feed button. The operation buttons 3a are arranged in an exposed state so as to be pressable on the outer surface of the printer cover 3. In the illustrated example, the operation buttons 3a are arranged below the lever 19 in a line in the up-down direction L1.

[0031] (Printing unit) As shown in FIGS. 2 to 5, the printing unit 4 includes a head unit 5 provided on the casing 2 side, and a platen unit 6 provided on the printer cover 3 side and combined with the head unit 5 so as to be separable.

[0032] The head unit 5 includes a head frame 20 made of, for example, a synthetic resin that forms the basic skeleton of the head unit 5, a head cover plate 21 made of, for example, a metal that is combined with the head frame 20 so as to cover the head frame 20 from the forward direction FW and the left-right direction L3, and gear covers 22, 23 made of, for example, metal that are combined with the head frame 20 so as to cover the head frame 20 from the left-right direction L3.

[0033] Furthermore, the head unit 5 is equipped with at least a thermal head 25, a movable blade 26, a drive mechanism 27, an operation lever 28, a return mechanism 29, and a platen lock mechanism 30. The thermal head 25, the movable blade 26, the drive mechanism 27, the operation lever 28, the return mechanism 29, and the platen lock mechanism 30 are attached mainly by utilizing the head frame 20, and are covered by the head cover plate 21 and the gear covers 22 and 23.

[0034] The head unit 5 configured as described above is attached inside the casing 2. Specifically, the head unit 5 is disposed above the recording paper storage section 16 and toward the front surface 13 of the casing 2, and is attached to the casing 2 mainly by fastening the head frame 20 with screws. In this embodiment, the head unit 5 is attached so that the cutting edge 26a of the movable blade 26 faces downward. The head unit 5 will be described in detail later.

[0035] The platen unit 6 includes a platen frame 40 made of, for example, synthetic resin that forms the basic skeleton of the platen unit 6, and a platen cover plate 41 made of, for example, metal that is combined with the platen frame 40 so as to cover the platen frame 40 from the forward direction FW and the left-right direction L3. Furthermore, the platen unit 6 includes at least a platen roller 45 and a fixed blade 46. The platen roller 45 and the fixed blade 46 are attached mainly by using the platen frame 40, and are covered by a platen cover plate 41.

[0036] The platen unit 6 configured as described above is attached to the inner surface of the printer cover 3 mainly via the platen cover plate 41. In this case, the platen unit 6 is attached at a position where it can be separably combined with the head unit 5 as the printer cover 3 is opened and closed. In this embodiment, the platen unit 6 is attached so that the blade tip 46a of the fixed blade 46 faces upward.

[0037] The platen unit 6 will now be described in detail. 3 to 6, the fixed blade 46 is supported by the platen frame 40 so that the blade tip 46a faces the head unit 5 when the head unit 5 and the platen unit 6 are combined. As shown in Fig. 6, the platen frame 40 has a platen storage space 47 for storing the platen roller 45 formed in a portion located rearward BK of the fixed blade 46, and also has support walls 48 for supporting the platen roller 45, disposed opposite each other in the left-right direction L3 with the platen storage space 47 in between.

[0038] The platen roller 45 is a rubber roller that transports the recording paper P to the outside of the printer cover 3, and is wound around a platen shaft 50 that extends in the left-right direction L3. The platen roller 45 is stored in the platen storage space 47 with a portion of its outer circumferential surface exposed on the head unit 5 side, and is rotatably supported by a support wall 48. Specifically, cylindrical platen bearings 51 are fitted to both ends of the platen shaft 50, which extends outward in the left-right direction L3 from the platen roller 45. This makes it possible to rotate the platen roller 45 even if the pair of platen bearings 51 are pressed down. A driven gear 52 is fixed to one end of the platen shaft 50, outward from the platen bearings 51 in the left-right direction L3.

[0039] The support walls 48 sandwich and fix the platen bearings 51 by using, for example, slit holes. As a result, the platen roller 45 is rotatably supported by the pair of support walls 48 via the pair of platen bearings 51 while being stored in the platen storage space 47. The pair of platen bearings 51 extend outward in the left-right direction L3 beyond the support wall 48, and when the printer cover 3 is closed, they are respectively accommodated in a pair of accommodation grooves 62 provided on the head unit 5 side, as shown in FIG. 5. In FIG. 5, the platen roller 45 and the platen bearing 51 of the platen unit 6 are mainly illustrated.

[0040] Next, the head unit 5 will be described in detail. As shown in FIGS. 3 to 5, the head unit 5 includes at least a thermal head 25, a movable blade 26, a drive mechanism 27, an operating lever 28, a return mechanism 29, and a platen lock mechanism 30. As shown in FIG.

[0041] 5, the thermal head 25 has a plurality of heating elements (not shown) arranged in a line along the left-right direction L3, and is attached to the head frame 20 so as to face the platen roller 45 when the printer cover 3 is in the closed position. The recording paper P can pass between the platen roller 45 and the thermal head 25. A coil spring (not shown) that biases the thermal head 25 toward the platen roller 45 is interposed between the thermal head 25 and the head frame 20. This ensures that the thermal head 25 is pressed against the recording paper P fed by the platen roller 45, enabling good printing by the printing unit 4.

[0042] The head frame 20 has a pair of side walls 60, 61 located outside the support wall 48 of the platen frame 40 in the platen unit 6 in the left-right direction L3. The pair of side walls 60, 61 are each formed with a pair of accommodation grooves 62 into which the pair of platen bearings 51 can be individually fitted. 7, the accommodating groove 62 is formed in a U-shape in a side view recessed toward the rear BK (one side in the second direction) in the front-rear direction L2, with an open opening 62a facing the front FW toward the platen unit 6. A groove bottom 62b of the accommodating groove 62 is formed flat. FIG. 7 illustrates the receiving groove 62 formed in one side wall portion 60, and omits illustration of other components as appropriate.

[0043] The inner surface of the accommodation groove 62 is formed so that the opening width narrows from the open opening 62a side toward the groove bottom 62b side, and an inclined guide protrusion 63 is formed to guide the platen bearing 51 toward the groove bottom 62b side. As a result, the accommodation groove 62 is formed so that the opening width is largest at the open opening 62a, and is formed so that the opening width is narrowest near the apex 63a of the guide protrusion 63. The guide protrusion 63 is formed in the accommodation groove 62, so that the platen bearing 51 can be guided so as to drop along the guide protrusion 63 toward the groove bottom 62b.

[0044] As described above, since the storage grooves 62 are formed in the pair of side wall portions 60, 61, when the head unit 5 and the platen unit 6 are combined, the pair of platen bearings 51 are fitted into the pair of storage grooves 62 and stored therein, as shown in Figures 5 and 7. At this time, the platen bearings 51 are stored in the storage grooves 62 in a state of contact with the groove bottom portion 62b.

[0045] 4, the movable blade 26 is attached to the head frame 20 via the drive mechanism 27 so that the blade tip 26a faces the platen unit 6 when the head unit 5 and the platen unit 6 are combined. In this case, the movable blade 26 is disposed to face the fixed blade 46 in the up-down direction L1, and is disposed to overlap the fixed blade 46 in the front-rear direction L2 when moved to the cutting position P1. As shown in Fig. 8, the movable blade 26 is a V-shaped plate-like blade formed so that the length from the base to the blade tip 26a gradually decreases from both ends toward the center. Fig. 8 is a perspective view showing a state in which the movable blade 26 is moved to the cutting position P1 and the recording paper P is cut between the fixed blade 46 and the movable blade 26.

[0046] 4, the movable blade 26 is attached to the rack member 300 via the movable blade holder 70. The movable blade 26 is configured to be movable in the vertical direction L1 relative to the head frame 20 by the operation of the drive mechanism 27. As a result, the movable blade 26 is supported relative to the fixed blade 46 so as to be movable in the vertical direction L1.

[0047] 4, 9, and 10, the drive mechanism 27 is a mechanism that moves the movable blade 26 between a cutting position P1 and a standby position P2. The cutting position P1 is a position where the movable blade 26 rides up onto the fixed blade 46, thereby cutting the recording paper P together with the fixed blade 46 (see FIG. 8). The standby position P2 is a position where the movable blade 26 is appropriately separated from the fixed blade 46 (see FIG. 4). The drive mechanism 27 includes a drive motor 75 , a drive intermediate wheel 76 , a two-stage intermediate wheel 77 , a drive pinion 78 , and a drive rack 71 .

[0048] As shown in FIG. 10, the driving motor 75 is a motor capable of rotating forward and backward, and is fixed to the inside of one of the side walls 60 of the head frame 20. The driving shaft of the driving motor 75 is connected to a reduction mechanism 75a. Furthermore, an output shaft 75b of the reduction mechanism 75a protrudes outward in the left-right direction L3 from the one of the side walls 60 of the head frame 20. The driving intermediate wheel 76 is disposed outward in the left-right direction L3 from the one of the side walls 60, and is connected to the output shaft 75b of the reduction mechanism 75a. Therefore, the driving intermediate wheel 76 rotates in conjunction with the rotation of the driving motor 75 via the reduction mechanism 75a.

[0049] As shown in FIGS. 9 and 10, the two-stage intermediate wheel 77 is disposed between the driving intermediate wheel 76 and the driving pinion 78 , and is rotatably supported by the intermediate support shaft 80 . The second-stage intermediate wheel 77 includes a large-diameter intermediate wheel 77a and a small-diameter intermediate wheel 77b formed with a smaller diameter than the large-diameter intermediate wheel 77a. The large-diameter intermediate wheel 77a meshes with the driving intermediate wheel 76 when the operating lever 28 is located at the lock position P3. As a result, the entire second-stage intermediate wheel 77 rotates in conjunction with the rotation of the driving intermediate wheel 76. The small-diameter intermediate wheel 77b is disposed outside the large-diameter intermediate wheel 77a in the left-right direction L3, and meshes with the driving pinion 78.

[0050] The drive pinion 78 is disposed so as to be located closer to the operating lever 28 than the small diameter intermediate wheel 77b and closer to the drive rack 71, and is fixed to the pinion support shaft 81 in a state where it is disposed coaxially with the pinion support shaft 81. As a result, the drive pinion 78 and the pinion support shaft 81 rotate integrally. Further, the drive pinion 78 meshes with the small diameter intermediate wheel 77 b and also meshes with the drive rack teeth 71 a of the drive rack 71 .

[0051] The drive rack 71 is provided on a rack member 300. As shown in Fig. 4, the rack members 300 are arranged not only on one side wall portion 60 side of the head frame 20 but also on the other side wall portion 61 side, and are arranged on both sides of the head frame 20 in the left-right direction L3. The pinion support shaft 81 is formed so as to penetrate the head frame 20 in the left-right direction L3, and connects a pair of drive pinions 78 arranged on both sides in the left-right direction L3 to each other. This allows the pair of drive pinions 78 to rotate together in a synchronous state via the pinion support shaft 81.

[0052] The rack member 300 is attached to both ends of the movable blade holder 70 along the left-right direction L3, and extends along the up-down direction L1. As a result, the rack member 300 is combined with the movable blade 26 via the movable blade holder 70. The rack member 300 is movable integrally with the movable blade 26. As shown in Fig. 11, the rack member 300 includes a drive rack 71 and a return rack 130, which will be described in detail later.

[0053] A plurality of drive rack teeth 71a are formed at equal intervals at a predetermined pitch over the entire area in the vertical direction L1 on the drive rack 71. As shown in Fig. 12, a pair of drive pinions 78 mesh with the drive rack teeth 71a. Therefore, as the pair of drive pinions 78 rotate, the movable blade 26 can be moved between the standby position P2 and the cutting position P1 via the drive rack 71.

[0054] In the following, in order to facilitate understanding of the configuration, a detailed description will be given of the drive pinion 78 and drive rack 71 located on one side wall portion 60 (the drive motor 75 side), and a description of the drive pinion 78 and drive rack 71 located on the other side wall portion 61 will be omitted.

[0055] Since the drive mechanism 27 is configured as described above, as shown in Fig. 4 and Fig. 9, the drive pinion 78 can be rotated by the rotation of the drive motor 75 via the drive intermediate wheel 76 and the two-stage intermediate wheel 77 (the large-diameter intermediate wheel 77a and the small-diameter intermediate wheel 77b). Therefore, the drive rack 71 can be moved in the direction of the arrow F1 together with a return rack 130 of the return mechanism 29, which will be described later, and the movable blade 26 can be moved in the same direction. This allows the movable blade 26 to be moved from the standby position P2 to the cutting position P1.

[0056] On the other hand, by rotating the driving motor 75 in the reverse direction, the driving pinion 78 can be rotated in the reverse direction via the driving intermediate wheel 76 and the two-stage intermediate wheel 77. Therefore, the driving rack 71 can be moved in the direction of the arrow F2 together with the return rack 130, and the movable blade 26 can be moved in the same direction. As a result, the movable blade 26 can be moved from the cutting position P1 to the standby position P2 and returned.

[0057] Incidentally, the intermediate support shaft 80 that supports the above-mentioned two-stage intermediate wheel 77 is fixed to a swing plate 90 that is arranged so as to be able to swing about a pinion support shaft 81 . 7, 9, and 13, the swing plate 90 is formed with an insertion hole (not shown) that penetrates the swing plate 90 in the left-right direction L3 and through which the pinion support shaft 81 is inserted. The swing plate 90 is arranged to be swingable along the wall surface of one of the side walls 60 with the pinion support shaft 81 inserted in the insertion hole (not shown).

[0058] The swing plate 90 includes a first plate portion 92 extending toward a gap between the intermediate drive wheel 76 and the drive rack 71, and a second plate portion 93 extending toward a swing axis O2 of a lock arm 140, which will be described later.

[0059] The intermediate support shaft 80 is formed to extend outward in the left-right direction L3 from the first plate portion 92. This allows the two-stage intermediate wheel 77 supported by the intermediate support shaft 80 to swing around the pinion support shaft 81 together with the swing plate 90. The second plate portion 93 is formed with an engagement pin 95 so as to protrude outward in the left-right direction L3.

[0060] The swing plate 90 configured in this manner is constantly urged by the urging force of the first urging member 100 in a direction in which the large-diameter intermediate wheel 77a of the second-stage intermediate wheel 77 meshes with the drive intermediate wheel . The first biasing member 100 is, for example, a coil spring, and has a coil portion 100a supported by a coil support shaft 105 protruding from one of the side wall portions 60, a first coil end portion 100b engaged with the head frame 20, and a second coil end portion 100c engaged with a locking protrusion 94 of the swing plate 90.

[0061] As a result, the swing plate 90 is positioned with the large diameter intermediate wheel 77a pressed against the drive intermediate wheel 76, since the second plate portion 93 is urged toward the operating lever 28 side by the urging force (elastic restoring force) of the first urging member 100. The first biasing member 100 is not limited to a coil spring, but may be, for example, a leaf spring.

[0062] Furthermore, the swing plate 90 is configured such that, as a result of the engagement pin 95 being pushed up by a push-up cam 113 (described later) in response to operation of the operating lever 28, the swing plate 90 swings about the pinion support shaft 81 against the biasing force of the first biasing member 100, and the second-stage intermediate wheel 77 moves away from the driving intermediate wheel 76. This makes it possible to release the meshing between the second-stage intermediate wheel 77 and the driving intermediate wheel 76.

[0063] As shown in Figures 4, 9 and 10, the operating lever 28 is disposed on one of the side wall portions 60 of the head frame 20, and is rotatably supported via a lever support shaft 106 that extends in the left-right direction L3 and is disposed parallel to the platen roller 45. The operating lever 28 is configured to be operable to push one of the side wall portions 60 counterclockwise when viewed from the side from the outside in the left-right direction L3, from the locked position P3 toward the disengaged position P4 or the unlocked position P5 described later, with the lever support shaft 106 as the center.

[0064] The lever support shaft 106 protrudes from the inner surface of the gear cover 22 toward one side wall portion 60. The central axis of the lever support shaft 106 corresponds to the rotation axis O1 of the operating lever .

[0065] The locked position P3 refers to a position where the platen unit 6 is locked relative to the head unit 5. The disengaged position P4 refers to a position where the swing plate 90 is swung by a push-up cam 113 (described later) in the operating lever 28, and the meshing between the large-diameter intermediate wheel 77a of the second-stage intermediate wheel 77 and the drive intermediate wheel 76 is released. The unlocked position P5 refers to a position where the lock of the platen unit 6 relative to the head unit 5 is released.

[0066] As shown in FIGS. 5, 9, 10 and 13, a lever plate 110 that is fan-shaped when viewed from the side is formed at the base end of the operating lever . A planetary shaft 111 protrudes outward in the left-right direction L3 from the outer surface of the lever plate 110. The lever plate 110 is formed with a push-up cam 113 and a regulating protrusion 114 that bulge outward in the radial direction.

[0067] The planetary shaft 111 is formed at a position offset from the lever support shaft 106. The push-up cam 113 is disposed clockwise from an engagement pin 95 formed on the swing plate 90, and is capable of contacting the engagement pin 95 when the operating lever 28 rotates from the lock position P3 toward the unlock position P5. Furthermore, an engagement projection 115 is formed on the outer surface of the push-up cam 113, protruding outward in the left-right direction L3.

[0068] The regulating protrusion 114 is disposed clockwise from the push-up cam 113, and is in contact with a regulating wall portion 116 formed on the head frame 20 from the clockwise side when the operating lever 28 is located at the lock position P3. Therefore, the entire operating lever 28 is restricted from rotating further clockwise, and is thereby positioned at the lock position P3. When the operating lever 28 moves to the unlocked position P5 and is further pushed downward, it can come into contact with the restricting wall portion 117 of the gear cover 22 shown in Fig. 3 from the counterclockwise direction. Therefore, the operating lever 28 is restricted from being pushed further downward beyond the unlocked position P5.

[0069] The tip of the operating lever 28 is fitted inside a connecting body 19a (see FIG. 2) of the lever 19 provided in the casing 2. Therefore, the operating lever 28 is operated in conjunction with the operation of the lever 19. This makes it possible to operate the operating lever 28 from the locked position P3 toward the unlocked position P5 in conjunction with the operation of the lever 19.

[0070] The operating lever 28 configured as described above is constantly biased in a direction (clockwise direction) toward the lock position P3 by the biasing force of the second biasing member 120, as shown in FIGS. The second biasing member 120 is, for example, a coil spring, and has a coil portion 120a supported on a coil support shaft (not shown) protruding from the inner surface of the gear cover 22, a first coil end 120b engaged with the inner surface of the gear cover 22, and a second coil end 120c engaged with a locking protrusion 115 of the operating lever 28.

[0071] As a result, the operating lever 28 is biased clockwise by the biasing force (elastic restoring force) of the second biasing member 120, so that the tip of the operating lever 28 is biased in the direction toward the lock position P3. As described above, the restricting protrusion 114 of the operating lever 28 comes into contact with the restricting wall portion 116 of the head frame 20, so that further rotation is restricted and the operating lever 28 is positioned at the lock position P3. The second biasing member 120 is not limited to a coil spring, but may be, for example, a leaf spring.

[0072] As shown in FIG. 4, when the movable blade 26 is stopped at the cutting position P1 due to, for example, the occurrence of a paper jam, the return mechanism 29 is a mechanism that uses the operating force (rotational force) associated with the operating lever 28 moving from the locked position P3 to the unlocked position P5 to move the movable blade 26 from the cutting position P1 to the standby position P2 before the platen lock mechanism 30 switches the platen roller 45 to the unlocked state.

[0073] 10, 14, and 15, the return mechanism 29 includes a return rack 130 formed on a rack member 300, a return pinion 131 meshing with return rack teeth 130a of the return rack 130, a return gear 132 supported rotatably about the rotation axis O1 in a state in which the return gear 132 is disposed coaxially with the rotation axis O1 of the operation lever 28, a planetary gear 134 meshing with a sun gear 133 provided integrally with the return gear 132 and revolving with the movement of the operation lever 28, and an internal gear 135 with which the planetary gear 134 meshes. The sun gear 133, the planetary gear 134, and the internal gear 135 form an acceleration mechanism 136 (see FIG. 14).

[0074] The return pinion 131 is rotatably supported by the pinion support shaft 81 in a state in which it is disposed outboard of the drive pinion 78 in the left-right direction L3. As a result, the return pinion 131 is disposed coaxially with the drive pinion 78. The return pinion 131 is capable of meshing with a return gear 132 that rotates in conjunction with the operation of the operating lever 28, and is rotated by the rotational force from the return gear 132. Furthermore, the return pinion 131 is capable of meshing with the return rack teeth 130 a of the return rack 130 .

[0075] As shown in Figs. 10 to 12 and 15, the return rack 130 is formed in the rack member 300 in a state in which it is disposed outside the driving rack 71 in the driving mechanism 27 in the left-right direction L3. That is, the rack member 300 includes the driving rack 71 and the return rack 130. The return rack 130 has a plurality of return rack teeth 130a. The plurality of return rack teeth 130a are formed in parallel with the plurality of driving rack teeth 71a in the left-right direction L3. The plurality of return rack teeth 130a and the plurality of driving rack teeth 71a are formed with a gap S in the left-right direction L3. As a result, the plurality of return rack teeth 130a and the plurality of driving rack teeth 71a are formed independently of each other. Note that the plurality of return rack teeth 130a and the plurality of driving rack teeth 71a may be configured not to have the gap S if they are formed independently of each other with, for example, different phases, as described later.

[0076] The return rack teeth 130a are provided at equal intervals at a predetermined pitch in the vertical direction L1. In this embodiment, the return rack teeth 130a and the driving rack teeth 71a have the same pitch and module. In this embodiment, the return rack teeth 130a and the driving rack teeth 71a have different phases. In this embodiment, the "pitch" refers to the center-to-center distance between adjacent teeth (between the driving rack teeth 71a or between the return rack teeth 130a) in the arrangement direction (vertical direction L1) of the driving rack teeth 71a and the return rack teeth 130a in the same rack. The "phase" refers to the center position of each driving rack tooth 71a and the center position of each return rack tooth 130a in the arrangement direction (vertical direction L1). That is, the phase difference between the multiple return rack teeth 130a and the multiple drive rack teeth 71a means that the center positions of the drive rack teeth 71a and the return rack teeth 130a are different in the tooth arrangement direction (up-down direction L1) between the return rack 130 and the drive rack 71. In the illustrated example, the phase difference between the multiple return rack teeth 130a and the multiple drive rack teeth 71a is half the pitch of the multiple return rack teeth 130a (multiple drive rack teeth 71a). These multiple return rack teeth 130a are formed so as to be located on the root side, not on the cutting edge 26a side, of the movable blade 26. As a result, the return rack 130 meshes with the return pinion 131 when the movable blade 26 is located at the cutting position P1, and is released from meshing with the return pinion 131 when the movable blade 26 is located at the standby position P2. Furthermore, at least some of the return rack teeth 130a (the return rack teeth 130a positioned at the top in the vertical direction D1) among the multiple return rack teeth 130a are arranged to protrude upward in the vertical direction L1 relative to the multiple drive rack teeth 71a.

[0077] Of the multiple return rack teeth 130a, the return rack teeth 130a located on the cutting edge 26a side of the movable blade 26 are formed as displaceable return rack teeth 130b. The return rack teeth 130b are formed at the tip of the rack arm 139. A base end of the rack arm 139 is connected to an end of the return rack 130 located on the cutting edge 26a side of the movable blade 26. Therefore, the rack arm 139 is a cantilever arm that is elastically deformable in a direction away from the return pinion 131 with the base end as a fulcrum. This allows the rack arm 139 to be elastically deformed in a direction away from the return pinion 131, making it possible to retract the return rack teeth 130b radially outward from the return pinion 131.

[0078] The reason why the return rack teeth 130b of the return rack 130 are formed so as to be retractable radially outward of the return pinion 131 will be briefly described. 9, the return rack teeth 130b of the return rack 130 may come into contact with the tips of the teeth of the return pinion 131. In this case, the movement of the return rack 130 may be blocked by the tips of the teeth of the return pinion 131. Considering this, the return rack teeth 130b are formed at the tip of the rack arm 139, so that the return rack teeth 130b can be retreated to the radially outer side of the return pinion 131 by elastic deformation of the rack arm 139 and can ride over the tooth tips of the return pinion 131. Therefore, after the return rack teeth 130b ride over the tooth tips of the return pinion 131, the return rack teeth 130b can be returned to their original positions by utilizing the elastic restoring force of the rack arm 139, so that the returned return rack teeth 130b can be appropriately meshed with the next tooth portion of the return pinion 131. This makes it possible to appropriately mesh the return rack teeth 130b of the return rack 130 with the return pinion 131 without causing the inconvenience of the movement of the return rack 130 being hindered.

[0079] 9, 10 and 15, the return gear 132 is rotatably supported by the lever support shaft 106 in a state in which it is disposed outside the lever plate 110 of the operating lever 28 in the left-right direction L3. As a result, the return gear 132 is disposed coaxially with the rotation axis O1 of the operating lever 28 and rotates in conjunction with the rotation of the operating lever 28.

[0080] The return gear 132 includes a gear plate 132a and a plurality of gear teeth 132b formed along the outer circumferential edge of the gear plate 132a. The plurality of gear teeth 132b are formed not around the entire circumference of the gear plate 132a but over a partial range in the circumferential direction. In this embodiment, the plurality of gear teeth 132b are formed over a range covering approximately half the circumference of the gear plate 132a. The plurality of gear teeth 132b are capable of meshing with the return pinion 131.

[0081] Of the multiple gear teeth 132b, the gear teeth 132b that first meshes with the return pinion 131 by operating the operating lever 28 from the locked position P3 toward the unlocked position P5 can be displaced radially inward of the return gear 132 and can be retracted from the teeth of the return pinion 131. The gear teeth 132b that first meshes with the return pinion 131 is the gear teeth 132b that is located furthest forward in the rotation direction Dr of the return gear 132 that rotates in conjunction with the rotation of the operating lever 28, among the multiple gear teeth 132b.

[0082] The gear teeth portion 132b is formed at the tip end of the elastic arm portion 132c. The base end of the elastic arm portion 132c is integrally formed with a portion of the outer periphery of the gear plate 132a where the gear teeth portion 132b is not formed, and extends in an arc shape in the clockwise direction along the outer periphery of the gear plate 132a. As a result, the elastic arm portion 132c is cantilevered to the outer periphery of the gear plate 132a via the base end, and is elastically deformable in the radial direction with the base end as a fulcrum. As a result, the elastic arm portion 132c elastically deforms toward the gear plate 132a, thereby displacing the gear tooth portion 132b radially inward of the return gear 132, and enabling it to retreat from the tooth portion of the return pinion 131.

[0083] 14, the sun gear 133 is integrally formed on the inner surface of the gear plate 132a, and is disposed coaxially with the rotation axis O1 of the operating lever 28. This allows the sun gear 133 to rotate together with the return gear 132 around the rotation axis O1.

[0084] The planetary gear 134 is rotatably supported by the operation lever 28 via the planetary shaft 111 while meshing with the sun gear 133. As a result, the planetary gear 134 revolves around the rotation axis O1 in response to the movement of the operation lever 28 as the operation lever 28 rotates about the rotation axis O1. An internal gear 135 with which the planetary gear 134 meshes is formed on the inner surface of the gear cover 22. Therefore, the planetary gear 134 revolves in accordance with the movement of the operating lever 28, and is capable of rotating while meshing with the internal gear 135.

[0085] By rotating the planetary gear 134 in this manner, the sun gear 133 and the return gear 132 can be rotated around the rotation axis O1, and the gear teeth portion 132b of the return gear 132 can be meshed with the return pinion 131.

[0086] Here, the return rack tooth 130a of the return rack 130 determines the angle of the return pinion 131 when the movable blade 26 is in the cutting position P1 so that a specific tooth 131t of the return pinion 131 engages with the gear tooth portion 132b that is located furthest forward in the rotation direction Dr of the return gear 132, which rotates in conjunction with the rotation of the operating lever 28 by operating the operating lever 28 from the locked position P3 to the unlocked position P5 (opening the printer cover 3).

[0087] As shown in FIG. 5, the platen lock mechanism 30 includes lock arms 140, 150 that are pivotable about a pivot axis O2 that is parallel to the platen roller 45, and is a mechanism that switches between a locked state in which the platen roller 45 is locked and an unlocked state in which the lock is released.

[0088] As shown in FIGS. 5, 9 and 10, one lock arm 140 is disposed on one side wall portion 60 side of the head frame 20, and the other lock arm 150 is disposed on the other side wall portion 61 side. When the operating lever 28 is positioned at the locked position P3, the pair of locking arms 140, 150 press the platen bearing 51 accommodated in the accommodation groove 62 from the open opening 62a side, and as the operating lever 28 moves from the locked position P3 toward the unlocked position P5, they swing about the swing axis O2 from the platen unit 6 toward the head unit 5, moving away from the platen bearing 51 to allow the platen bearing 51 to come out of the accommodation groove 62.

[0089] Therefore, the platen lock mechanism 30 of this embodiment utilizes the pair of lock arms 140, 150 to simultaneously lock and unlock the pair of platen bearings 51.

[0090] The lock arm 140 and the other lock arm 150 extend in the left-right direction L3 and are connected to each other via a long connecting shaft portion 141 disposed parallel to the platen roller 45. 10, the connecting shaft 141 is a cylindrical shaft that is formed to penetrate the head frame 20 in the left-right direction L3 and is rotatably supported by one side wall portion 60 and the other side wall portion 61. The central axis of the connecting shaft 141 is set to the oscillation axis O2.

[0091] The one lock arm 140 and the other lock arm 150 are connected to both ends of the connecting shaft portion 141. This allows the one lock arm 140 and the other lock arm 150 to swing synchronously around the swing axis O2 via the connecting shaft portion 141.

[0092] The connecting shaft portion 141 is disposed so as to be located between the accommodation groove 62 and the return gear 132 in the up-down direction L1, and to be located rearward BK of the accommodation groove 62 in the front-rear direction L2.

[0093] In this embodiment, a pair of lock arms 140, 150 arranged in the left-right direction L3 are connected to each other via the connecting shaft 141 so as to be able to swing, but the present invention is not limited to this. For example, the pair of lock arms 140, 150 and the connecting shaft 141 may be formed as a single member by bending a single sheet metal or the like.

[0094] One of the lock arms 140 will now be described in detail. 16, the lock arm 140 is disposed above the accommodating groove 62 and is formed to extend in the front-rear direction L2. The base end of the lock arm 140 is connected to an end of a connecting shaft portion 141. A lock claw portion 145 is formed at the tip of the lock arm 140, which covers the platen bearing 51 accommodated in the accommodating groove 62 from the open opening 62a side of the accommodating groove 62. This makes it possible to hold the platen bearing 51 such that the platen bearing 51 is sandwiched between the lock claw portion 145 and the groove bottom portion 62b of the accommodating groove 62.

[0095] The outer surface of the locking claw portion 145 is formed as an inclined guide surface 145b that guides the platen bearing 51 into the accommodating groove 62 when the platen bearing 51 is set in the accommodating groove 62. This guide surface 145b is formed so as to define a V-groove that is V-shaped in side view between it and the guide protrusion 63 on the accommodating groove 62 side.

[0096] Furthermore, an engagement wall 146 is formed at the base end of the lock arm 140 so as to protrude outward in the left-right direction L3. The engagement wall 146 is a wall with which a lever protrusion 112 (see FIG. 17) provided on the operating lever 28 comes into contact after the push-up cam 113 swings the swing plate 90 via the engagement pin 95 when the operating lever 28 is operated from the locked position P3 toward the unlocked position P5.

[0097] As a result, the entire lock arm 140 is pushed by the lever protrusion 112 via the engagement wall 146 in response to operation of the operating lever 28, and is configured to swing clockwise about the swing axis O2. In other words, the lock arm 140 is configured to swing upward about the swing axis O2 from the platen unit 6 side toward the head unit 5 side. Therefore, the locking claw portion 145 of the locking arm 140 gradually separates from the platen bearing 51 as the operating lever 28 is operated, and when the operating lever 28 reaches the lock position P3, the locking claw portion 145 retreats from the accommodation groove 62 to the head unit 5 side, thereby opening the opening 62a. This makes it possible to allow the platen bearing 51 to come out of the accommodation groove 62.

[0098] 5, 13, and 16, the platen lock mechanism 30 includes a detachment arm 200. In this embodiment, the detachment arm 200 is provided on the side wall portion 60 on one side in the left-right direction L3. The detachment arm 200 is swingably provided on an arm support shaft 210 that protrudes outward in the left-right direction L3 from the side wall portion 60. The arm support shaft 210 extends in the left-right direction L3 and is disposed parallel to the platen roller 45.

[0099] The arm support shaft 210 is disposed at a position different from the connecting shaft portion 141 that pivotally supports the lock arm 140, and the lever support shaft 106 that pivotally supports the operating lever 28. As shown in Fig. 13, at least a portion of the arm support shaft 210 overlaps with the maximum outer diameter portion of the platen roller 45 in the front-rear direction L2. Furthermore, at least a portion of the arm support shaft 210 overlaps with the platen bearing 51 in the front-rear direction L2. Moreover, in the up-down direction L1, the arm support shaft 210 is disposed on the opposite side to the lever support shaft 106 with the platen bearing 51 in between.

[0100] 5, the detachment arm 200 is disposed adjacent to the operation lever 28 in the left-right direction L3. The detachment arm 200 is disposed inside the operation lever 28 in the left-right direction L3. As shown in FIG. 16, the detachment arm 200 includes an arm body 201, a boss 203, and a detachment pressing surface 205.

[0101] The arm body 201 has a plate shape along a plane perpendicular to the left-right direction L3. The arm body 201 is provided so as to be freely swingable about the arm support shaft 210 by the arm support shaft 210 penetrating therethrough in the left-right direction L3.

[0102] The boss 203 is formed on the arm body 201 radially outward from the arm support shaft 210. The boss 203 protrudes from the arm body 201 outward in the left-right direction L3, that is, toward the operation lever 28. As shown in Figs. 13 and 17, the operation lever 28 is formed with a boss accommodating groove 118 into which the boss 203 can be inserted. The boss accommodating groove 118 is recessed so as to extend in the tangent direction of a virtual circle having a curvature radius between the arm support shaft 210 and the boss 203 and centered on the arm support shaft 210. The boss accommodating groove 118 has an abutment surface 118f that abuts against the outer circumferential surface of the boss 203 when the operation lever 28 rotates from the lock position P3 toward the unlock position P5. The abutment surface 118f of the operation lever 28 is formed so as to abut against the outer circumferential surface of the boss 203 when the operation lever 28 moves a set angle from the lock position P3 toward the unlock position P5. The timing at which the operating lever 28 reaches the boss abutment position P6 (see FIG. 17) where the abutment surface 118f abuts against the outer circumferential surface of the boss 203 is, for example, when the lock arm 140 is retracted from the movement trajectory when the platen bearing 51 is released from the accommodation groove 62. The timing at which the operating lever 28 reaches the boss abutment position P6 is not limited to this, and may be at least when the lock arm 140 starts to move from the locked state to the unlocked state and the lock arm 140 is not restricting the platen bearing 51 from being released from the accommodation groove 62. When the operating lever 28 is further rotated toward the unlocked position P5, the abutment surface 118f presses the boss 203, causing the arm main body 201 to rotate around the arm support shaft 210.

[0103] 13, the boss 203 is disposed on the opposite side of the platen bearing 51 across the arm support shaft 210 in the vertical direction L1. This ensures a long distance from the lever support shaft 106, which is the rotation center of the operating lever 28, to the boss 203. Therefore, when the operating lever 28 is rotated from the locked position P3 toward the unlocked position P5, the boss 203 can be efficiently pressed.

[0104] As shown in FIG. 16, the detachment pressing surface 205 is formed on the arm body 201 on the opposite side of the boss 203 in the vertical direction L1 across the arm support shaft 210. The detachment pressing surface 205 is formed facing the forward direction FW. The arm body 201 rotates around the arm support shaft 210, and the detachment pressing surface 205 presses the platen bearing 51 housed inside the housing groove 62 to the forward direction FW. At this time, it is preferable that the detachment pressing surface 205 is formed so as to be as close to a right angle as possible to the groove bottom 62b in a state where it abuts against the platen bearing 51 in contact with the groove bottom 62b of the housing groove 62. In other words, it is preferable that the detachment pressing surface 205 is formed so as to extend in the vertical direction L1 in a state where it abuts against the platen bearing 51 in contact with the groove bottom 62b of the housing groove 62. This allows the pressing force of the detachment pressing surface 205 to be efficiently transmitted to the platen bearing 51 in the housing groove 62.

[0105] As the operating lever 28 rotates from the locked position P3 toward the unlocked position P5, the removal arm 200 as described above rotates around the arm support shaft 210 and presses the platen bearing 51 from inside the accommodating groove 62 toward the open opening 62a, causing the platen bearing 51 to remove from the accommodating groove 62.

[0106] 5, when the platen unit 6 of this embodiment is combined with the head unit 5, the driven gear 52 can mesh with a platen gear train mechanism (not shown) that is disposed on the other side wall portion 61 of the head frame 20. The platen gear train mechanism operates by receiving power from a drive motor (not shown) for driving the platen roller 45, and plays a role of transmitting the power to the driven gear 52. As a result, when the head unit 5 and the platen unit 6 are combined, the platen roller 45 can be rotated to feed the recording paper P.

[0107] (Thermal Printer Function) Next, the operation of the thermal printer 1 configured as above will be described. First, a case where the head unit 5 and the platen unit 6 are combined will be described. In this case, as shown in Fig. 2, after the rolled recording paper P is inserted and set in the recording paper storage section 16 of the casing 2, the platen unit 6 can be brought close to the head unit 5 by closing the printer cover 3. Then, as shown in Fig. 1, by completely closing the printer cover 3, the head unit 5 and the platen unit 6 can be combined with the recording paper P sandwiched between the thermal head 25 and the platen roller 45.

[0108] In addition, as the printer cover 3 is closed, the platen bearing 51 of the platen roller 45 is guided by the guide protrusion 63 of the accommodating groove 62 and the guide surface 145b of the locking claw portion 145 so as to fit into the accommodating groove 62, and is accommodated in the accommodating groove 62.

[0109] After being pushed by the platen bearing 51, the lock arms 140, 150 swing around the swing axis O2 due to the force of a return spring (not shown) and return to their original position, and use the lock claw portion 145 to press the platen bearing 51 from the open opening 62a side of the accommodating groove 62. As a result, as shown in FIG. 5, the pair of lock arms 140, 150 can be used to press the pair of platen bearings 51 housed in the pair of housing grooves 62, respectively, and the platen bearings 51 can be prevented from slipping out of the housing grooves 62. Therefore, the platen roller 45 can be maintained in a locked state by using the platen lock mechanism 30. In addition, when the printer cover 3 is closed, it is preferable that the abutment surface 118f does not come into contact with the boss 203 when the lock arms 140, 150 are pressed by the platen bearings 51. This makes it possible to suppress the movement of the detachment arm 200 during the closing operation of the printer cover 3. However, the detachment arm 200 may move slightly as long as the platen bearings 51 do not come into contact with the detachment pressing surface 205 until the lock arms 140, 150 are returned by the return springs.

[0110] This makes it possible to lock the combination of the head unit 5 and the platen unit 6, and at the same time, to lock the printer cover 3 to the casing 2. By combining the head unit 5 and the platen unit 6, the thermal head 25 and the platen roller 45 are pressed against each other with a predetermined pressure with the recording paper P sandwiched therebetween. After the recording paper P passes between the movable blade 26 and the fixed blade 46, it is pulled out from the discharge port 18 to the outside of the casing 2. Furthermore, the driven gear 52 of the platen roller 45 is engaged with the platen gear train mechanism on the head unit 5 side.

[0111] Next, printing of various information on the recording paper P will be briefly described. In this case, the drive motor is driven to rotate the driven gear 52 via the platen gear train mechanism, thereby rotating the platen roller 45, and the recording paper P sandwiched between the platen roller 45 and the thermal head 25 can be fed toward the paper outlet 18. At the same time, a control signal corresponding to the print data is output to the thermal head 25 to appropriately heat the heating elements, thereby making it possible to clearly print various characters, figures, etc. on the fed recording paper P. The printed recording paper P passes between the fixed blade 46 and the movable blade 26 .

[0112] Next, the process of cutting the recording paper P will be briefly described. In this case, the driving motor 75 is driven to rotate the driving intermediate wheel 76 shown in Fig. 9. This allows the driving pinion 78 to rotate via the two-stage intermediate wheel 77 (the large-diameter intermediate wheel 77a and the small-diameter intermediate wheel 77b), and the driving rack 71 can be moved in the direction of the arrow F1 together with the return rack 130. This allows the movable blade 26 to move from the standby position P2 to the cutting position P1, and the recording paper P can be sandwiched and cut between the movable blade 46 as shown in Fig. 8. As a result, the cut recording paper P can be used as, for example, a receipt or a ticket.

[0113] After the recording paper P is cut, the driving motor 75 is rotated in the reverse direction. This allows the driving pinion 78 to rotate in the reverse direction via the driving intermediate wheel 76 and the two-stage intermediate wheel 77, and as shown in Fig. 9, the driving rack 71 can be moved together with the return rack 130 in the direction of the arrow F2. As a result, the movable blade 26 can be moved from the cutting position P1 to the standby position P2 and returned.

[0114] Furthermore, when the recording paper P is cut, the return pinion 131 is disengaged from the gear teeth portion 132b of the return gear 132 and is allowed to rotate freely. Therefore, even if the return rack teeth 130a, 130b of the return rack 130 mesh with the return pinion 131 when the movable blade 26 moves to the cutting position P1, the return pinion 131 can be rotated freely. Therefore, the drive rack 71 and the return rack 130 can be moved without being affected by the return pinion 131, and the recording paper P can be cut.

[0115] Next, we will explain the series of operations that occur when a paper jam occurs between the movable blade 26 and the fixed blade 46, by operating the operating lever 28 to clear the paper jam, while unlocking the platen unit 6 and opening the printer cover 3. 18, the operating lever 28 is operated from the locked position P3 toward the unlocked position P5 against the biasing force of the second biasing member 120. This causes the operating lever 28 to rotate counterclockwise around the rotation axis O1, and with the movement of the operating lever 28, the planetary gear 134 meshed with the internal gear 135 can be made to revolve counterclockwise around the rotation axis O1 while rotating clockwise around the planetary shaft 111. As the planetary gear 134 rotates, the sun gear 133 and the return gear 132 can be rotated counterclockwise about the rotation axis O1.

[0116] Here, when a paper jam occurs between the movable blade 26 and the fixed blade 46 and the movable blade 26 is stopped at the cutting position P1, when the operating lever 28 is rotated from the locked position P3 toward the unlocked position P5, the first gear tooth portion 132b of the return gear 132 among the multiple gear tooth portions 132b meshes with a predetermined tooth 131t of the return pinion 131, as shown in Fig. 19. Here, the multiple return rack teeth 130a of the return rack 130 are out of phase with the multiple drive rack teeth 71a of the drive rack 71. As a result, the drive pinion 78 and the return pinion 131 have different gear tooth positions (angles) in the circumferential direction around their central axes. When the movable blade 26 is in the cutting position P1, the circumferential angle of the return pinion 131 is determined so that the first gear tooth portion 132b of the return gear 132 among the multiple gear tooth portions 132b and a specified tooth 131t of the return pinion 131 mesh stably in the same positional relationship.

[0117] For comparison, a case will be considered in which a plurality of return rack teeth 130a of the return rack 130 and a plurality of drive rack teeth 71a of the drive rack 71 are in the same phase, at the same pitch, and in the same module, and entirely overlap when viewed from the left-right direction L3, as shown in Figures 20 and 21. In this case, when the movable blade 26 is at the cutting position P1, if the first gear tooth portion 132b of the return gear 132 among the plurality of gear tooth portions 132b is positioned to face a predetermined tooth 131t of the return pinion 131, as shown in Figure 20, the first gear tooth portion 132b of the return gear 132 may mesh with the predetermined tooth 131t of the return pinion 131 on the front side in the rotation direction Dr of the return pinion 131, and as shown in Figure 21, the first gear tooth portion 132b of the return gear 132 may mesh with the predetermined tooth 131t of the return pinion 131 on the rear side in the rotation direction Dr of the return pinion 131. That is, the amount of movement of the movable blade 26 when the operation lever 28 reaches the unlocking position P5 is different between the case shown in FIG. 20 and the case shown in FIG. 21. In this way, if the rotation position of the return gear 132 when the gear teeth portion 132b meshes with the predetermined tooth 131t of the return pinion 131 is different, the amount of movement of the movable blade 26 when the operation lever 28 moves to P5 after meshing is different. Note that the case where the return pinion 131 meshes with the front side in the rotation direction Dr of the return pinion 131 is a state in which the gear teeth portion 132b has entered between the predetermined tooth 131t and the front tooth 131f located in front of the predetermined tooth 131t. The case where the return pinion 131 meshes with the rear side in the rotation direction Dr is a state in which the gear teeth portion 132b contacts the top of the predetermined tooth 131t (a state in which the gear teeth portion 132b does not fully enter between the predetermined tooth 131t and the rear tooth 131r located behind the predetermined tooth 131t).

[0118] As described above, the return rack 130, which is out of phase with the drive rack 71, determines the angle of the return pinion 131 so that the first gear tooth portion 132b of the return gear 132 and a specified tooth 131t of the return pinion 131 mesh stably in the same positional relationship.

[0119] 22, as the operating lever 28 rotates counterclockwise, the push-up cam 113 comes into contact with the engagement pin 95, and applies an external force to the swing plate 90 via the engagement pin 95. Therefore, by further operating the operating lever 28, the push-up cam 113 can push up the swing plate 90, and the swing plate 90 can be swung clockwise around the pinion support shaft 81 against the biasing force of the first biasing member 100.

[0120] As a result, the second-stage intermediate wheel 77 attached to the swing plate 90 can be separated from the driving intermediate wheel 76, and the meshing between the second-stage intermediate wheel 77 and the driving intermediate wheel 76 can be released. Therefore, the position of the operating lever 28 at this time corresponds to the disengagement position P4.

[0121] Furthermore, at the same time as the swing plate 90 swings, the sun gear 133 and the return gear 132 rotate counterclockwise in response to the operation of the operating lever 28, so that at the timing when the meshing between the two-stage intermediate wheel 77 and the driving intermediate wheel 76 is released, the first gear tooth portion 132b of the return gear 132 can be meshed with the return pinion 131. This allows the return pinion 131 to rotate clockwise.

[0122] Therefore, by further operating the operating lever 28 from the disengaged position P4 shown in Figure 22 toward the unlocked position P5, the remaining gear teeth 132b of the return gear 132 can be sequentially engaged with the return pinion 131, as shown in Figure 23, and the return pinion 131 can be continuously rotated clockwise. Therefore, the return rack 130 meshing with the return pinion 131 can be moved in the direction of the arrow F2, and the movable blade 26 can be forcibly returned from the cutting position P1 to the standby position P2. This makes it possible to eliminate the state in which the movable blade 26 overlaps with the fixed blade 46, and to clear the paper jam.

[0123] When the movable blade 26 is returned to the standby position P2 by using the return pinion 131, the drive rack 71 also moves together with the return rack 130, causing the drive pinion 78 to rotate. At this time, as described above, the meshing between the two-stage intermediate wheel 77 and the drive intermediate wheel 76 is released, so that the drive pinion 78 and the two-stage intermediate wheel 77 meshing therewith can each be rotated freely. Therefore, the movable blade 26 can be returned to the standby position P2 without being affected by the drive pinion 78 and the two-stage intermediate wheel 77.

[0124] In addition, when the movable blade 26 returns to the standby position P2, the return rack teeth 130a, 130b of the return rack 130 are disengaged from the return pinion 131. Therefore, when the movable blade 26 is returned to the standby position P2 and the paper jam is cleared, the meshing between the return rack teeth 130a, 130b of the return rack 130 and the return pinion 131 can be released.

[0125] Furthermore, at the timing when the movable blade 26 returns to the standby position P2, the lever protrusion 112 of the operating lever 28 comes into contact with the engagement wall portion 146 of one of the lock arms 140, and applies an external force to the lock arm 140 via the engagement wall portion 146. This allows the lock arm 140 to swing about the swing axis O2 from the platen unit 6 side toward the head unit 5 side. Therefore, as the lock arm 140 swings, the lock claw portion 145 can be gradually separated from the platen bearing 51.

[0126] 23, when the operating lever 28 is rotated a predetermined angle from the locked position P3 toward the unlocked position P5 and reaches the boss abutment position P6, the abutment surface 118f abuts against the outer circumferential surface of the boss 203. When the operating lever 28 is further rotated toward the unlocked position P5, the boss 203 provided on the radially outer side of the arm support shaft 210 is pressed, and the removal arm 200 rotates around the arm support shaft 210, pressing the platen bearing 51 from inside the accommodation groove 62 toward the open opening 62a.

[0127] 24, when the operating lever 28 is rotated to the unlocked position P5, the lock arm 140 rotates from the locked state to the unlocked state, and the platen bearing 51 is released from the accommodation groove 62 by the removal arm 200. At this time, the removal arm 200 presses the platen bearing 51 until the roller center of the platen roller 45 moves toward the opening 62a beyond the apex 63a of the guide projection 63.

[0128] In this way, by positioning the operation lever 28 at the unlocked position P5, the platen roller 45 can be switched to an unlocked state using the platen lock mechanism 30, and the head unit 5 and the platen unit 6 can be separated. As a result, the printer cover 3 to which the platen unit 6 is attached can be opened.

[0129] As described above, according to the printing unit 4 and the thermal printer 1 of this embodiment, when the driving pinion 78 is rotated by the driving mechanism 27, the movable blade 26 moves between the standby position P2 and the cutting position P1 together with the rack member 300 meshing with the driving pinion 78. The movable blade 26 rides up onto the fixed blade 46 at the cutting position P1, thereby cutting the recording paper P. After cutting the recording paper P, the movable blade 26 returns from the cutting position P1 to the standby position P2. When the movable blade 26 stops at the cutting position P1 due to a paper jam that occurs between the fixed blade 46 and the movable blade 26 at the cutting position P1, the return mechanism 29 rotates the return pinion 131, thereby moving the return rack 130 meshing with the return pinion, and the movable blade 26 together with the rack member 300 from the cutting position P1 to the standby position P2. In such a configuration, the drive rack 71 and the return rack 130 are formed separately and independently. Therefore, the drive rack 71 can be designed to be suitable for moving the movable blade 26 with the drive mechanism 27 without considering the operation when the movable blade 26 is returned by the return mechanism 29. In addition, the return rack 130 can be designed to be suitable for returning the movable blade 26 with the return mechanism 29 without considering the operation when the movable blade 26 is moved by the drive mechanism 27. In this way, the drive mechanism 27 and the drive mechanism 27 and return mechanism 29 can each be designed with a high degree of freedom.

[0130] Furthermore, by making at least one of the phase and pitch different between the drive rack teeth 71a and the return rack teeth 130a, it is possible to make the operation of the drive mechanism 27 and the return mechanism 29 different. This makes it possible to make the operation of the drive mechanism and the return mechanism different without making the drive rack teeth and the return rack teeth different in radial positions of the drive pinion and the return pinion that mesh with the drive rack teeth and the return rack teeth. This makes it difficult to change the layout of the peripheral parts of the drive rack teeth and the return rack teeth, facilitating design.

[0131] Furthermore, when the operating lever 28 is rotated between the locked position P3 and the unlocked position P5, the return gear 132 rotates via a planetary gear 134 provided on the operating lever 28 (planetary shaft 111) in accordance with the rotation of the operating lever 28. By meshing a plurality of gear teeth 132b of the return gear 132 with the return pinion 131, the rotation of the return gear 132 can be transmitted to the return rack 130 via the return pinion 131. As a result, by operating the operating lever 28, the return rack 130 can be moved, and the movable blade 26 can be moved from the cutting position P1 to the standby position P2.

[0132] Furthermore, the return rack 130 can be moved only while the multiple gear teeth 132b formed in a range covering a part of the circumferential direction of the return gear 132 are engaged with the return pinion 131 by rotating the operating lever 28. In other words, when the multiple gear teeth 132b are not engaged with the return pinion 131, the return pinion 131 does not rotate and the return rack 130 does not move. This makes it possible to appropriately set the timing for moving the return rack 130 according to the rotation angle of the operating lever 28.

[0133] In addition, when the movable blade 26 is at the cutting position P1, the return rack teeth 130a of the return rack 130 mesh with the return pinion 131, and the gear teeth 132b located at the front of the plurality of gear teeth 132b in the rotation direction Dr of the return gear 132 that rotates with the rotation of the operation lever 28 by operating the operation lever 28 from the lock position P3 to the unlock position P5. This makes it possible to unify the timing at which the gear teeth 132b located at the front of the rotation direction Dr of the return pinion 131 meshes with the return pinion 131 when the operation lever 28 is rotated while the cutting teeth are at the cutting position P1. This makes it possible to stabilize the movement timing and movement amount of the return rack 130 when the operation lever 28 is rotated, and the movable blade 26 can be reliably returned from the cutting position P1 to the standby position P2.

[0134] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. The embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. The embodiments and their modifications include, for example, those that can be easily imagined by a person skilled in the art, those that are substantially the same, those that are within the scope of the equivalents, and the like.

[0135] For example, in the above embodiment, the return rack teeth 130a and the drive rack teeth 71a may have different pitches (intervals between the return rack teeth 130a and the drive rack teeth 71a). The return rack teeth 130a and the drive rack teeth 71a may all have different phases, modules, and pitches. The return rack teeth 130a and the drive rack teeth 71a may be positioned differently in the front-rear direction L2, and the outer diameter dimensions of the drive pinion 78 and the return pinion 131 may be different. The return rack teeth 130a and the drive rack teeth 71a may have different tooth widths and tooth heights (dimensions from the tooth bottom to the tooth tip). That is, when the return rack teeth 130a are provided in parallel with the drive rack teeth 71a, for example, they may be configured such that at least a part of them protrudes when viewed from the parallel direction.

[0136] In the above embodiment, the rack members 300 are arranged on both sides of the head frame 20 in the left-right direction L3, but the rack members 300 may be arranged on only one side of the head frame 20 in the left-right direction L3. In the above embodiment, the movable blade 26 and the like are provided in the head unit 5 (the other unit) and the fixed blade 46 is provided in the platen unit 6 (one unit), but the present invention is not limited to this configuration. The movable blade 26 and the like may be provided in the platen unit 6 (one unit) and the fixed blade 46 may be provided in the head unit 5 (the other unit).

[0137] In addition, in the above embodiment, the return rack 130 and the drive rack 71 are arranged in parallel, but the return rack 130 and the drive rack 71 may be arranged in other appropriate positions instead of in parallel.

[0138] Furthermore, in the above embodiment, the configuration of each part has been described in detail, but the configuration can be changed as appropriate. For example, the configuration for moving the rack member 300 together with the movable blade 26 is not limited to that shown in the above embodiment, and can be changed to another configuration as appropriate. [Explanation of symbols]

[0139] 1. Thermal printer 2...Casing (printer body) 3. Printer cover 4...Printing unit 5...Head unit (other unit, one unit) 6...Platen unit (one unit, the other unit) 16...Recording paper storage section 25…Thermal head 26…Movable blade 27...Drive mechanism 28…Operating lever 29...Return mechanism 45...Platen roller 46…Fixed blade 71...Drive rack 71a...Drive rack teeth 78…Drive pinion 121…Return pinion 130…Return rack 130a...Return rack teeth 130b...Return rack teeth 131…Return pinion 131t…tooth 132…Return gear 132b...Gear teeth 300…Rack components P...Recording paper P1…Cutting position P2…Standby position P3…Lock position P5…Unlocked position

Claims

1. a head unit having a thermal head for printing on recording paper; a platen unit having a platen roller for transporting the recording paper and separably combined with the head unit; a fixed blade provided in one of the head unit and the platen unit; a movable blade provided in the other of the head unit and the platen unit and movable relative to the fixed blade, The other unit is a rack member connected to the movable blade and movable integrally with the movable blade; a drive mechanism having a drive pinion that meshes with the rack member and that moves the movable blade between a standby position away from the fixed blade and a cutting position where the movable blade rides on the fixed blade; a return mechanism that has a return pinion that meshes with the rack member and moves the movable blade from the cutting position to the standby position in a state in which the movable blade is stopped at the cutting position, The rack member is a drive rack having a plurality of drive rack teeth that mesh with the drive pinion; a return rack formed separately from the drive rack and having a plurality of return rack teeth that mesh with the return pinion; The drive rack and the return rack are arranged in parallel, The drive rack teeth of the drive rack and the return rack teeth of the return rack are different in at least one of phase and pitch. Printing unit.

2. an operation lever that is rotatable between a lock position at which the platen unit is locked to the head unit and a release position at which the platen unit is released from the head unit; a return gear provided rotatably in response to rotation of the operating lever and having a plurality of gear teeth capable of meshing with the return pinion; The printing unit according to claim 1 .

3. The printing unit according to claim 2 , wherein the plurality of gear teeth are formed over a portion of the circumferential direction of the return gear.

4. The printing unit described in claim 3, wherein the return rack teeth of the return rack are formed so that when the movable blade is in the cutting position, the return pinion meshes with the gear tooth portion among the multiple gear tooth portions that is located furthest forward in the rotational direction of the return gear, which rotates in conjunction with the rotation of the operating lever by operating the operating lever from the lock position toward the release position.

5. A printing unit according to any one of claims 1 to 4, a printer body having a recording paper storage section for storing the recording paper and having one of the head unit and the platen unit attached thereto; a printer cover rotatably connected to the printer body, and to which the other of the head unit and the platen unit is attached.

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