printer

Abstract

To provide a printer which can prevent the occurrence of slacking during back feed of an ink ribbon.SOLUTION: A printer includes a feeding shaft, a winding shaft, a conveying section, a print head, and a rotational force generating mechanism. The feeding shaft rotatably holds a supply roll around which an ink ribbon is wound. The winding shaft rotatably holds a recovery roll which winds up the ink ribbon fed from the supply roll. The conveying section conveys a medium to be printed along the ink ribbon moving from the supply roll toward the recovery roll. The print head performs printing by bringing the ink ribbon into contact with the medium to be printed which is conveyed by the conveying section. The rotational force generating mechanism generates rotational force in a direction for winding up the ink ribbon on the winding shaft during back feed in which the feeding shaft is rotated in a direction opposite to a feeding direction of the ink ribbon and the ink ribbon is moved in the opposite direction.SELECTED DRAWING: Figure 7

Description

Technical Field

[0006] , ,

[0001] Embodiments of the present invention relate to a printer that prints on a printing medium using an ink ribbon.

Background Art

[0002] A printer that prints on a printing medium using an ink ribbon has a feed shaft for attaching a supply roll around which the ink ribbon is wound, a printing head, and a take-up shaft for attaching a take-up roll around which the used ink ribbon is wound. When printing on a printing medium with this printer, the printing medium is conveyed, the ink ribbon is fed out from the supply roll, the printing head is passed through with the printing medium and the ink ribbon overlapped, and the used ink ribbon after printing is collected by the take-up roll.

[0003] The ink ribbon may become slack or wrinkled due to the printing operation. If the ink ribbon becomes slack or wrinkled, printing defects may occur. Therefore, a printer using an ink ribbon usually has a mechanism for eliminating slack or wrinkles in the ink ribbon.

Prior Art Documents

[0007] The problem that this invention aims to solve is to provide a printer that can prevent slack from occurring during backfeed of the ink ribbon. [Means for solving the problem]

[0008] The printer of this embodiment includes a feed shaft, a take-up shaft, a transport unit, a print head, and a rotational force generating mechanism. The feed shaft rotatably holds a supply roll around which an ink ribbon is wound. The take-up shaft rotatably holds a recovery roll that has been wound up from the ink ribbon fed out from the supply roll. The transport unit transports the printing medium along the ink ribbon as it moves from the supply roll to the recovery roll. The print head prints by bringing the ink ribbon into contact with the printing medium transported by the transport unit. The rotational force generating mechanism generates rotational force on the take-up shaft in the direction of winding the ink ribbon when backfeeding occurs, which involves rotating the feed shaft in the opposite direction to the ink ribbon's feed direction to move the ink ribbon in the reverse direction. The rotational force generating mechanism includes a one-way bearing and a tension spring. The one-way bearing has a rotating member that rotates freely when the winding shaft rotates in the winding direction and rotates integrally with the winding shaft during backfeed, when the winding shaft rotates in the opposite direction to the winding direction. The tension spring has one end fixed to the rotating member and is stretched by the rotation of the rotating member in the opposite direction, wrapping around the rotating member and generating a restoring force that rotates the rotating member in the winding direction. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is an external perspective view showing a printer according to an embodiment. [Figure 2] Figure 2 is a perspective view showing the printer in Figure 1 with the cover open. [Figure 3] Figure 3 is a perspective view showing the label paper roll used in the printer shown in Figure 1. [Figure 4] Figure 4 is a schematic diagram showing the internal structure of the printer shown in Figure 1. [Figure 5] Figure 5 is a cross-sectional perspective view showing the rotational force generation mechanism connected to one end of the winding shaft in Figure 4 and its surrounding structure. [Figure 6]Figure 6 is a plan view of the drive mechanism that drives the winding shaft shown in Figure 4, as seen from the direction of arrow F6 in Figure 5. [Figure 7] Figure 7 is a side view of the structure shown in Figure 5, viewed from the direction of arrow F7. [Figure 8] Figure 8 is a rear view of the structure shown in Figure 7, viewed from the direction of arrow F8. [Modes for carrying out the invention]

[0010] One embodiment of the present invention will be described below with reference to the drawings. As shown in Figures 1 and 2, the label printer 100 (hereinafter simply referred to as printer 100) has a case 2 and a cover 4. The case 2 constitutes the lower housing of the printer 100, and the cover 4 constitutes the upper housing of the printer. The cover 4 is connected to the case 2 via a hinge (not shown) provided on its rear end. The cover 4 is rotatable between the closed position shown in Figure 1 and the open position shown in Figure 2. In the following description, with the cover 4 in the closed position as shown in Figure 1, the output port 9 side of the printer 100 is considered the front side, and the up, down, left, and right directions of the printer 100 are defined as viewed from the front side.

[0011] Case 2 is a rectangular box shape with an open top, and has a notch 3 on its front wall for attaching a functional unit (not shown), such as a peeling unit. Case 2 has a front panel 5 that attaches to the notch 3 when a functional unit is not attached. Figures 1 and 2 show the front panel 5 attached to the notch 3. The printer 100 has a slit-shaped output port 9 between the front panel 5 and the cover 4 of Case 2 for feeding out the printed label paper 11.

[0012] The cover 4 is a rectangular box shape with an open bottom. On the front side of the left and right side walls of the cover 4, there is an opening lever 6 for opening the cover 4 and a fixing hook 16 that operates when the opening lever 6 is operated. The fixing hook 16 engages with the engaging part on the case 2 when the cover 4 is in the closed position, locking the cover 4 in the closed position. On the top wall of the cover 4 are the operation / display panel 7 and the power button 8.

[0013] As shown in Figure 3, the label paper 11 to be installed inside the case 2 consists of a long, strip-shaped backing sheet 12 with multiple rectangular labels 13 attached at equal intervals to one side. The labels 13 have an adhesive layer on the side facing the backing sheet 12, making them detachable from the backing sheet 12, and allowing them to be attached to other items after being peeled off the backing sheet 12. The label paper roll 15 is made by winding the label paper 11 around a paper tube 14 with the side of the backing sheet 12 with the labels 13 attached facing outwards.

[0014] As shown in Figure 2, the printer 100 has a pair of left and right paper holders 17 for mounting the label paper roll 15. The label paper roll 15 is mounted between the pair of paper holders 17 in the orientation shown in Figure 3. That is, the label paper roll 15 is mounted in the printer 100 in a position where the label side 13 of the label paper 11 pulled from the label paper roll 15 faces upward. Therefore, when the label paper 11 pulled from the label paper roll 15 is transported toward the output port 9, the label paper roll 15 rotates counterclockwise when viewed from the right side. The label paper 11 is an example of a printing medium.

[0015] As shown in FIGS. 2 and 4, the printer 100 has a platen roller 21 that applies a forward conveying force to the label paper 11 to draw the label paper 11 out of the label paper roll 15. The platen roller 21 can also rotate in the reverse direction to back-feed the label paper 11. The platen roller 21 is disposed on the front side within the case 2 adjacent to the discharge port 9. The platen roller 21 rotates in contact with the surface of the label paper 11 opposite to the surface where the label 13 is attached to the backing paper 12 of the label paper 11. The printer 100 has a conveyance path 1 for conveying the label paper 11 drawn out from the label paper roll 15. When the cover 4 is rotated to the open position in FIG. 2, a part of the conveyance path 1 can be opened.

[0016] The printer 100 has a printing head 23 for printing on each label 13 of the label paper 11 conveyed through the conveyance path 1. The printing head 23 is disposed on the opposite side (upper side) of the conveyance path 1 with respect to the platen roller 21 and is pressed toward the platen roller 21. Therefore, a conveying force can be applied to the label paper 11 from the platen roller 21 at the position where the printing head 23 is pressed against the platen roller 21. The printing head 23 is a component on the cover 4 side. The cover 4 includes a pressing spring (not shown) that presses the printing head 23 toward the platen roller 21. The platen roller 21 is an example of a conveying unit that conveys the printing medium.

[0017] The printing head 23 can perform printing by a thermal transfer method and can also perform printing by a thermal printing method. When performing printing by the thermal transfer method, an ink ribbon 25 is interposed between the printing head 23 and the label paper 11, the ink ribbon 25 is conveyed in the same direction at the same speed as the label paper 11, and the ink on the ink ribbon 25 is melted by the heat of the printing head 23 and fixed on the label 13.

[0018] As shown in FIG. 4, the printer 100 includes a supply roll 26 around which a long strip-shaped ink ribbon 25 is wound around a paper tube, and a recovery roll 27 that winds up the used ink ribbon 25 that has passed through the printing head 23 using a paper tube. The ink ribbon 25 stretched between the supply roll 26 and the recovery roll 27 passes between the printing head 23 and the platen roller 21 so as to sequentially overlap a plurality of labels 13 of the label paper 11 conveyed through the conveyance path 1. The ink ribbon 25 holds ink that is transferred to each label 13 of the label paper 11 by heat.

[0019] The pair of paper holders 17 (FIG. 2) in the case 2 rotatably hold both ends of the paper tube 14 of the label paper roll 15. Inside the cover 4, there are a feed shaft 18 attached to the paper tube of the supply roll 26 of the ink ribbon 25 and a take-up shaft 19 (not shown in FIG. 2) attached to the paper tube of the recovery roll 27. The feed shaft 18 and the take-up shaft 19 are spaced apart from each other and extend in parallel.

[0020] When printing on each label 13 of the label paper 11, the printer 100 rotates the platen roller 21 counterclockwise in FIG. 4 to convey the label paper 11 pulled out from the label paper roll 15 in the forward direction (left direction in FIG. 4) at a constant speed. Also, at this time, the printer 100 rotates the take-up shaft 19 to which the recovery roll 27 is attached clockwise in FIG. 4 to convey the ink ribbon 25 in the forward direction at the same speed. In this state, the printer 100 prints on each label 13 of the label paper 11 via the printing head 23.

[0021] If printing continues, the ink ribbon 25 may become loose or wrinkled. It has been found that this looseness or wrinkle of the ink ribbon 25 can be resolved by backfeeding the ink ribbon 25. When backfeeding the ink ribbon 25, the print head 23 is moved to a retracted position spaced upward from the platen roller 21, and the feed shaft 18 to which the supply roll 26 is attached is rotated counterclockwise in Figure 4 to rewind the ink ribbon 25. This pulls the used ink ribbon 25 out from the recovery roll 27, causing the recovery roll 27 to rotate counterclockwise in Figure 4.

[0022] When the backfeed of the ink ribbon 25 is terminated, the rotation of the feed shaft 18 is stopped. At this time, since the recovery roll 27 is rotating counterclockwise in Figure 4, the recovery roll 27 will try to continue rotating counterclockwise due to inertia. In this case, new slack may be created in the ink ribbon 25 between the supply roll 26 which has stopped rotating and the recovery roll 27 which continues to rotate. The amount of slack in this case will increase as the diameter (weight) of the recovery roll 27 increases.

[0023] In order to prevent slack that occurs during backfeed of the ink ribbon 25, the printer 100 of this embodiment is equipped with a rotational force generating mechanism 30 that generates a rotational force in the winding direction of the ink ribbon 25 relative to the winding shaft 19 of the recovery roll 27 during backfeed. The rotational force generating mechanism 30 and its surrounding structure will be described below with reference to Figures 5 to 8.

[0024] Figure 5 is a cross-sectional perspective view showing the rotational power generation mechanism 30 and its surrounding structure; Figure 6 is a plan view of the drive mechanism 40 that drives the winding shaft 19 of the recovery roll 27, viewed from the left side of the printer 100 (in the direction of arrow F6 in Figure 5); Figure 7 is a side view of the structure in Figure 5, viewed from the direction of arrow F7; and Figure 8 is a rear view of the rotational power generation mechanism 30, viewed from the direction of arrow F8 in Figure 7 (rear of the printer 100).

[0025] To make the explanation easier to understand, in each figure, arrow A indicates the rotation direction of the feed shaft 18 and the winding shaft 19 and the travel direction of the ink ribbon 25 when the ink ribbon 25 is transported in the forward direction, and arrow B indicates the rotation direction of the feed shaft 18 and the winding shaft 19 and the travel direction of the ink ribbon 25 when the ink ribbon 25 is back-fed.

[0026] As shown in Figure 5, the printer 100 has a wheel 10 for coaxially connecting one end (left end) of the winding shaft 19. The wheel 10 is rotatably housed in a recess 281 of a frame 28 fixed to the left side of the cover 4. When attaching the recovery roll 27 to the printer 100, the wheel 10 receives and meshes with a bevel-tooth gear (not shown) provided on the left end of the winding shaft 19 of the recovery roll 27. As a result, the winding shaft 19 rotates in the direction in which the wheel 10 rotates. The wheel 10 is coaxially and integrally equipped with a rotating shaft 20 that extends through the bottom of the recess 281. In other words, the rotating shaft 20 is an axis that is coaxially and integrally connected to the winding shaft 19.

[0027] The rotating shaft 20 extends to the left, passing through the bottom of the recess 281 in the frame 28. The left end of the rotating shaft 20 is rotatably supported by a rotating member 32 (described later) and a one-way bearing 31, which are rotatably attached to a sheet metal 29 fixed to the cover 4 at a position spaced apart to the left of the frame 28. The sheet metal 29 has a constriction 291 with a projection height of 2 to 3 times its thickness. This constriction 291 functions as a bearing that rotatably supports the left end of the rotating member 32. Therefore, a bearing to rotatably support the left end of the rotating shaft 20 can be omitted, and the axial thickness of the rotational force generating mechanism 30 can be reduced.

[0028] The rotating shaft 20 has two one-way bearings 22 and 31 mounted coaxially in an annular configuration. One of the one-way bearings 22, closer to the wheel 10, is mounted between the gear 24 and the rotating shaft 20. The other one-way bearing 31, on the sheet metal 29 side, is a component of the rotational force generating mechanism 30 and is mounted between the rotating member 32 of the rotational force generating mechanism 30 and the rotating shaft 20. The one-way bearing 31 of the rotational force generating mechanism 30 is positioned adjacent to the one-way bearing 22 on the side opposite to the wheel 10.

[0029] The one-way bearing 22 comprises an inner sheath fixed to the rotating shaft 20 and an outer sheath attached to the outside of the inner sheath via a sprag. The one-way bearing 22 transmits rotational force to the rotating shaft 20 when the gear 24 is rotated in the forward direction by the drive mechanism 40 shown in Figure 6, and also allows the rotating shaft 20 to rotate in the reverse direction when the gear 24 is stopped. In other words, when the ink ribbon 25 is being transported in the forward direction, the one-way bearing 22 transmits the rotational force transmitted from the motor 41 (Figure 6) via the gear 24 to the rotating shaft 20, causing the recovery roll 27 to rotate in the direction of winding the ink ribbon 25. Furthermore, when the motor 41 (gear 24) is stopped and the ink ribbon 25 is being back-fed, the one-way bearing 22 allows the recovery roll 27 (rotating shaft 20) to rotate in the reverse direction (free spin).

[0030] The one-way bearing 31 of the rotational force generating mechanism 30 comprises an inner sheath fixed to the rotating shaft 20 and an outer sheath attached to the outside of the inner sheath via a sprag. The one-way bearing 31 transmits the rotational force to the rotating member 32 when the rotating shaft 20 rotates in the reverse direction due to the backfeed of the ink ribbon 25, and allows the rotating shaft 20 to rotate freely relative to the rotating member 32 when the ink ribbon 25 is being transported in the forward direction.

[0031] As shown in Figure 6, the drive mechanism 40 that rotates the gear 24 includes a motor 41, first to fourth gears 43 to 46 that sequentially mesh with a gear 42 fixed to the rotation shaft of the motor 41, and a fifth gear 47 with a torque limiter provided between the fourth gear 46 and the gear 24.

[0032] As shown in Figures 7 and 8, the rotational force generating mechanism 30 has a tension spring 33 whose lower end is fixed to a sheet metal 29 and whose upper end is fixed to a rotating member 32. The tension spring 33 is an example of an elastic member that elastically deforms during backfeed. The sheet metal 29 has a hook 292 for hooking the lower end 331 of the tension spring 33. The rotating member 32 has a hook 321 protruding from its outer circumferential surface for hooking the upper end 332 of the tension spring 33. Figures 7 and 8 show the initial state in which the tension spring 33 has not undergone elastic deformation.

[0033] The rotating member 32 has an annular retaining groove 322 for winding the stretched tension spring 33. The hook 321 protrudes from the bottom of the retaining groove 322. A sheet metal 29 is positioned to the left of the retaining groove 322. The sheet metal 29 functions as a retaining plate to prevent the tension spring 33, which is wound around the retaining groove 322, from coming out of the retaining groove 322 due to its restoring force.

[0034] When the rotating shaft 20 rotates clockwise in Figure 7 during backfeed, the rotating member 32 rotates clockwise in Figure 7, stretching the tension spring 33 and wrapping it around the retaining groove 322. When the tension spring 33 is stretched, its restoring force acts in a direction that causes the rotating member 32 to rotate counterclockwise in Figure 7. In other words, during backfeed of the ink ribbon 25, tension is always applied to the ink ribbon 25 between the print head 23 and the recovery roll 27. To put it another way, when backfeeding the ink ribbon 25, a rotational force is applied to the rotating shaft 20 in a counterclockwise direction in Figure 7, and a rotational force is applied to the winding shaft 19 in the direction that winds the ink ribbon 25.

[0035] In other words, when the rotational force generating mechanism 30 of this embodiment is used, when the rotation of the feed shaft 18 in the reverse direction is stopped at the end of the backfeed of the ink ribbon 25 and the rotation of the supply roll 26 is stopped, the recovery roll 27 does not continue to rotate in the reverse direction due to inertia, and slack in the ink ribbon 25 as shown by the dashed line 251 in Figure 6 does not occur. Therefore, according to this embodiment, wrinkles in the ink ribbon 25 are eliminated by the backfeed of the ink ribbon 25, and no new slack in the ink ribbon 25 occurs after the backfeed, thereby improving print quality.

[0036] Although embodiments of the present invention have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. The embodiments described above can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. The embodiments described above and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. The invention described in the original claims of this application is listed below. [1] A feed shaft that rotatably holds a supply roll around which an ink ribbon is wound, A winding shaft that rotatably holds a recovery roll on which the ink ribbon fed out from the supply roll has been wound, A transport unit that transports the printing medium along the ink ribbon moving from the supply roll toward the recovery roll, A print head that prints by bringing the ink ribbon into contact with the printing medium being transported by the transport unit, During backfeed, in which the feed shaft is rotated in the opposite direction to the feed direction of the ink ribbon to move the ink ribbon in the reverse direction, a rotational force generating mechanism is provided to generate a rotational force on the winding shaft in the direction of winding the ink ribbon. A printer that has [a certain feature]. [2] The aforementioned rotational force generation mechanism is A one-way bearing having a rotating member that rotates freely when the winding shaft rotates in the winding direction and rotates integrally with the winding shaft during backfeed when the winding shaft rotates in the opposite direction to the winding direction, The system includes an elastic member that elastically deforms upon rotation of the rotating member in the opposite direction, and whose restoring force causes the rotating member to rotate in the winding direction. [1] The printer described above. [3] The elastic member has one end fixed to the rotating member and is a tension spring that stretches and wraps around the rotating member when the rotating member rotates in the opposite direction. [2] The printer described below. [4] It has a retaining plate that is fixed to the rotating member and, together with the rotating member, forms a retaining groove around which the tension spring is wound, thereby restraining its movement. [3] The printer described below. [5] The other end of the tension spring is fixed to the retaining plate. [4] The printer described below. [Explanation of symbols]

[0037] 2...Case, 4...Cover, 11...Label paper, 18...Feeding shaft, 19...Take-up shaft, 20...Rotating shaft, 21...Platen roller, 22...One-way bearing, 23...Print head, 24...Gear, 25...Ink ribbon, 26...Supply roll, 27...Collection roll, 29...Sheet metal, 291...Drawer, 292...Hook, 30...Rotational power generation mechanism, 31...One-way bearing, 32...Rotating member, 321...Hook, 322...Retaining groove, 33...Tension spring, 40...Drive mechanism, 41...Motor, 100...Label printer.

Claims

1. A feed shaft that rotatably holds a supply roll around which an ink ribbon is wound, A winding shaft that rotatably holds a recovery roll on which the ink ribbon fed out from the supply roll has been wound, A transport unit that transports the printing medium along the ink ribbon moving from the supply roll toward the recovery roll, A print head that prints by bringing the ink ribbon into contact with the printing medium being transported by the transport unit, The device includes a rotational force generating mechanism that generates rotational force on the winding shaft in the winding direction of the ink ribbon during backfeed, in which the feed shaft is rotated in the opposite direction to the feed direction of the ink ribbon to move the ink ribbon in the reverse direction. The aforementioned rotational force generation mechanism is A one-way bearing having a rotating member that rotates freely when the winding shaft rotates in the winding direction and rotates integrally with the winding shaft during backfeed when the winding shaft rotates in the opposite direction to the winding direction, The device includes a tension spring having one end fixed to the rotating member, which is stretched by the rotation of the rotating member in the opposite direction and wraps around the rotating member, thereby generating a restoring force that rotates the rotating member in the winding direction, Printer.

2. It has a retaining plate that is fixed to the rotating member and, together with the rotating member, forms a retaining groove around which the tension spring is wound, thereby restraining its movement. The printer according to claim 1.

3. The other end of the tension spring is fixed to the retaining plate. The printer according to claim 2.

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