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]

[0001] An embodiment of the present invention relates to a printer that uses an ink ribbon to print on a print-receiving medium. [Background technology]

[0002] A printer that uses an ink ribbon to print on a print medium has a feed shaft on which a supply roll with the ink ribbon wound is attached, a print head, and a take-up shaft on which a recovery roll with the used ink ribbon wound is attached. When printing on a print medium with this printer, the print medium is transported, the ink ribbon is fed from the supply roll, the print medium and the ink ribbon are overlapped and passed through the print head, and the used ink ribbon after printing is recovered by the recovery roll.

[0003] The ink ribbon may become loose or wrinkled during printing. If the ink ribbon becomes loose or wrinkled, printing defects may occur. For this reason, printers that use ink ribbons are usually equipped with a mechanism to eliminate the slack and wrinkles in the ink ribbon. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 58-82265 Summary of the Invention [Problem to be solved by the invention]

[0005] It is known that the slack or wrinkles in the ink ribbon can be eliminated by, for example, backfeeding the ink ribbon in the opposite direction. When backfeeding the ink ribbon, the feed shaft is rotated in the reverse direction to pull out the used ink ribbon from the recovery roll.

[0006] However, when the ink ribbon is fed back, the recovery roll continues to rotate due to inertia after the reverse rotation of the delivery shaft is stopped, which may cause new slack in the ink ribbon between the print head and the recovery roll.

[0007] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a printer capable of preventing the occurrence of slack in the ink ribbon when it is fed back. [Means for solving the problem]

[0008] The printer of the embodiment has 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 around which the ink ribbon fed from the supply roll is wound. The transport unit transports the print medium along the ink ribbon moving from the supply roll toward the recovery roll. The print head prints by bringing the ink ribbon into contact with the print medium transported by the transport unit. The rotational force generating mechanism generates a rotational force in the direction of winding the ink ribbon on the take-up shaft during backfeeding, which rotates the feed shaft in a direction opposite to the feed direction of the ink ribbon to move the ink ribbon in the opposite direction. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is an external perspective view showing a printer according to an embodiment. [Diagram 2] FIG. 2 is a perspective view showing the printer of FIG. 1 with its cover open. [Diagram 3] FIG. 3 is a perspective view showing a label paper roll used in the printer of FIG. [Figure 4] FIG. 4 is a schematic diagram showing the internal structure of the printer of FIG. [Diagram 5] FIG. 5 is a cross-sectional perspective view showing a rotation force generating mechanism connected to one end of the winding shaft in FIG. 4 and its surrounding structure. [Figure 6]6 is a plan view of a drive mechanism for driving the winding shaft in FIG. 4, as viewed from the direction of arrow F6 in FIG. [Figure 7] FIG. 7 is a side view of the structure of FIG. 5 as seen from the direction of arrow F7. [Figure 8] FIG. 8 is a rear view of the structure of FIG. 7 as seen from the direction of arrow F8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. As shown in Figures 1 and 2, a 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 at the rear end side. The cover 4 is rotatable between a closed position shown in Figure 1 and an open position shown in Figure 2. In the following description, in the state shown in Figure 1 where the cover 4 is placed in the closed position, the discharge outlet 9 side of the printer 100 is defined as 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 that is open at the top, and has a cutout portion 3 in its front wall for attaching a functional unit (not shown), such as a peeling unit. Case 2 has a front panel 5 that is attached to cutout portion 3 when no functional unit is attached. Figures 1 and 2 show the front panel 5 attached to cutout portion 3. Printer 100 has a slit-shaped outlet 9 between the front panel 5 and cover 4 of case 2, through which label paper 11 is fed after printing.

[0012] The cover 4 is in the shape of a rectangular box that is open at the bottom. On the front sides of the left and right side walls of the cover 4, there are an opening lever 6 for opening the cover 4 and a fixed hook 16 that is operated by operating the opening lever 6. When the cover 4 is in the closed position, the fixed hook 16 engages with an engaged portion on the case 2 side, locking the cover 4 in the closed position. An operation / display panel 7 and a power button 8 are provided on the top wall of the cover 4.

[0013] As shown in Fig. 3, the label paper 11 to be attached inside the case 2 is made by affixing multiple rectangular labels 13 at equal intervals to one side of a long, strip-shaped backing paper 12. The labels 13 have an adhesive layer on the surface facing the backing paper 12, and are detachable from the backing paper 12. After being peeled off from the backing paper 12, the labels 13 can be affixed to other items. The label paper roll 15 is made by winding the label paper 11 around a cardboard tube 14 with the side of the backing paper 12 to which the labels 13 are affixed facing outwards.

[0014] As shown in Fig. 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 Fig. 3. In other words, the label paper roll 15 is mounted in the printer 100 with the surface of the label paper 11 pulled out from the label paper roll 15 facing upwards. Therefore, when the label paper 11 pulled out from the label paper roll 15 is transported towards the discharge outlet 9, the label paper roll 15 rotates counterclockwise when viewed from the right side. The label paper 11 is an example of a print-receiving medium.

[0015] As shown in Figures 2 and 4, the printer 100 has a platen roller 21 that applies a forward transport force to the label paper 11 to pull the label paper 11 from the label paper roll 15. The platen roller 21 can also rotate in the reverse direction to backfeed the label paper 11. The platen roller 21 is located on the front side of the case 2, adjacent to the discharge opening 9. The platen roller 21 rotates in contact with the surface of the label paper 11 opposite the surface on which the label 13 is affixed to the backing paper 12. The printer 100 has a transport path 1 that transports the label paper 11 pulled out from the label paper roll 15. Part of the transport path 1 can be opened by rotating the cover 4 to the open position shown in Figure 2.

[0016] The printer 100 has a print head 23 that prints on each label 13 of the label paper 11 transported through the transport path 1. The print head 23 is located on the opposite side (upper side) of the transport path 1 relative to the platen roller 21, and is pressed against the platen roller 21. Therefore, a transport force can be applied from the platen roller 21 to the label paper 11 at a position where the print head 23 is pressed against the platen roller 21. The print head 23 is configured on the cover 4 side. The cover 4 is equipped with a pressing spring (not shown) that presses the print head 23 against the platen roller 21. The platen roller 21 is an example of a transport section that transports the print-receiving medium.

[0017] The print head 23 is capable of printing by thermal transfer printing and thermal printing. When printing by thermal transfer printing, an ink ribbon 25 is interposed between the print head 23 and the label paper 11, and the ink ribbon 25 is transported in the same direction and at the same speed as the label paper 11. The ink on the ink ribbon 25 is melted by the heat of the print head 23 and fixed to the label 13.

[0018] As shown in Fig. 4, the printer 100 includes a supply roll 26 having a long strip-shaped ink ribbon 25 wound around a paper tube, and a recovery roll 27 that winds up the used ink ribbon 25 that has passed the print head 23 onto the paper tube. The ink ribbon 25 stretched between the supply roll 26 and the recovery roll 27 passes between the print head 23 and the platen roller 21 so as to be sequentially overlapped with the multiple labels 13 of the label paper 11 transported via the transport path 1. The ink ribbon 25 holds ink that is transferred to each label 13 of the label paper 11 by heat.

[0019] A pair of paper holders 17 (Fig. 2) inside the case 2 rotatably hold both ends of the paper core 14 of the label paper roll 15. Inside the cover 4, there are a feed shaft 18 attached to the paper core 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 core of the recovery roll 27. The feed shaft 18 and the take-up shaft 19 extend parallel to each other and are spaced apart from each other.

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

[0021] Continuing the printing operation may cause slack or wrinkles in the ink ribbon 25. It has been found that such slack or wrinkles in the ink ribbon 25 can be eliminated by backfeeding the ink ribbon 25. When backfeeding the ink ribbon 25, the print head 23 is moved to a retracted position spaced above the platen roller 21, and the feed shaft 18 to which the supply roll 26 is attached is rotated counterclockwise in FIG. 4 to rewind the ink ribbon 25. This causes the used ink ribbon 25 to be pulled out from the recovery roll 27, which then rotates counterclockwise in FIG. 4.

[0022] When the backfeed of the ink ribbon 25 is to be terminated, the rotation of the delivery shaft 18 is stopped. At this time, since the recovery roll 27 is rotating counterclockwise in FIG. 4, the recovery roll 27 tries to continue rotating counterclockwise due to inertial force. In this case, there is a possibility that new slack will be generated in the ink ribbon 25 between the supply roll 26, which has stopped rotating, and the recovery roll 27, which continues to rotate. In this case, the amount of slack increases as the diameter (weight) of the recovery roll 27 increases.

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

[0024] Figure 5 is a cross-sectional oblique view showing the rotational force generating 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 from the left side of the printer 100 (the direction of arrow F6 in Figure 5), Figure 7 is a side view of the structure in Figure 5 from the direction of arrow F7, and Figure 8 is a rear view of the rotational force generating mechanism 30 from the direction of arrow F8 in Figure 7 (rear of the printer 100).

[0025] For ease of understanding, in each figure, the rotation direction of the feed shaft 18 and the take-up shaft 19 and the running direction of the ink ribbon 25 when the ink ribbon 25 is transported in the forward direction are indicated by arrow A, and the rotation direction of the feed shaft 18 and the take-up shaft 19 and the running direction of the ink ribbon 25 when the ink ribbon 25 is back-fed are indicated by arrow B.

[0026] As shown in FIG. 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 and arranged in a recess 281 of a frame 28 fixed to the left side of the cover 4. When the recovery roll 27 is attached to the printer 100, the wheel 10 receives and meshes with a bevel gear (not shown) provided on the left end of the winding shaft 19 of the recovery roll 27. Therefore, the winding shaft 19 rotates in the direction in which the wheel 10 rotates. The wheel 10 is coaxially and integrally provided with a rotating shaft 20 that extends through the bottom of the recess 281. In other words, the rotating shaft 20 is a shaft that is coaxially and integrally connected to the winding shaft 19.

[0027] The rotating shaft 20 extends leftward through the bottom of the recess 281 of the frame 28. The left end of the rotating shaft 20 is rotatably supported by a rotating member 32 (described later) rotatably attached to a metal plate 29 fixed to the cover 4 at a position spaced apart from the left side of the frame 28, and a one-way bearing 31. The metal plate 29 has a diaphragm 291 with a protruding height of two to three times its plate thickness. This diaphragm 291 functions as a bearing that rotatably supports the left end of the rotating member 32. For this reason, a bearing that rotatably supports the left end of the rotating shaft 20 can be omitted, and the axial thickness of the rotation force generating mechanism 30 can be reduced.

[0028] Two one-way bearings 22, 31 are coaxially mounted on the rotating shaft 20. One of the one-way bearings 22, which is closer to the wheel 10, is attached between the gear 24 and the rotating shaft 20. The other one-way bearing 31 on the metal plate 29 side is a component of the rotational force generating mechanism 30, and is attached between the rotating shaft 20 and a rotating member 32 of the rotational force generating mechanism 30. The one-way bearing 31 of the rotational force generating mechanism 30 is disposed adjacent to the one-way bearing 22 on the side opposite to the wheel 10.

[0029] The one-way bearing 22 includes an inner sheath fixed to the rotating shaft 20 and an outer sheath attached to the outside of the inner sheath via sprags. The one-way bearing 22 transmits a rotational force to the rotating shaft 20 when the gear 24 is rotated in the forward direction by the driving mechanism 40 shown in FIG. 6, and allows the rotating shaft 20 to rotate in the reverse direction when the gear 24 is stopped. In other words, the one-way bearing 22 functions to transmit a rotational force transmitted from the motor 41 (FIG. 6) via the gear 24 to the rotating shaft 20 when the ink ribbon 25 is conveyed in the forward direction, thereby rotating the recovery roll 27 in the direction in which the ink ribbon 25 is wound up. The one-way bearing 22 also functions to allow the recovery roll 27 (rotating shaft 20) to rotate in the reverse direction (idling) when the ink ribbon 25 is back-fed with the motor 41 (gear 24) stopped.

[0030] The one-way bearing 31 of the rotational force generating mechanism 30 includes an inner sheath fixed to the rotating shaft 20 and an outer sheath attached to the outside of the inner sheath via sprags. 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 idly relative to the rotating member 32 when the ink ribbon 25 is being transported in the forward direction.

[0031] As shown in FIG. 6, a drive mechanism 40 that rotates gear 24 includes a motor 41, first to fourth gears 43 to 46 that sequentially mesh with a gear 42 fixed to the rotating shaft of motor 41, and a fifth gear 47 with a torque limiter provided between the fourth gear 46 and 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 the metal plate 29 and whose upper end is fixed to the rotating member 32. The tension spring 33 is an example of an elastic member that elastically deforms during backfeed. The metal plate 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 is not elastically deformed.

[0033] The rotating member 32 has an annular holding groove 322 around which the stretched tension spring 33 is wound. The hook 321 protrudes from the bottom of the holding groove 322. A metal plate 29 is disposed on the left side of the holding groove 322. The metal plate 29 functions as a pressing plate for preventing the tension spring 33, which is wound around the holding groove 322, from coming off the holding groove 322 due to its restoring force.

[0034] When the rotating shaft 20 rotates in the clockwise direction in Fig. 7 during backfeeding, the rotating member 32 rotates in the clockwise direction in Fig. 7, and the tension spring 33 is stretched and wound around the retaining groove 322. When the tension spring 33 is stretched, its restoring force acts in a direction that rotates the rotating member 32 in the counterclockwise direction in Fig. 7. In other words, when the ink ribbon 25 is backfeeding, a tension is always applied to the ink ribbon 25 between the print head 23 and the recovery roll 27. In other words, when the ink ribbon 25 is backfeeding, a rotational force in the counterclockwise direction in Fig. 7 is applied to the rotating shaft 20, and a rotational force in a direction that winds up the ink ribbon 25 is applied to the take-up shaft 19.

[0035] In other words, when the rotational force generating mechanism 30 of this embodiment is used, when the reverse rotation of the delivery shaft 18 is stopped to stop the rotation of the supply roll 26 at the end of the backfeed of the ink ribbon 25, 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 Fig. 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 is generated in the ink ribbon 25 after the backfeed, thereby improving print quality.

[0036] Although the embodiment of the present invention has been described above, the above-mentioned embodiment is presented as an example and is not intended to limit the scope of the invention. The above-mentioned embodiment 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 above-mentioned embodiment and its modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0037] 2...case, 4...cover, 11...label paper, 18...feed 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...recovery roll, 29...sheet metal, 291...diaphragm, 292...hook, 30...rotational force generating 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 take-up shaft that rotatably holds a recovery roll that takes up the ink ribbon fed from the supply roll; a conveying unit that conveys a print medium along the ink ribbon that moves from the supply roll toward the recovery roll; a print head that prints by bringing the ink ribbon into contact with the print-receiving medium transported by the transport unit; a rotational force generating mechanism that generates a rotational force on the winding shaft in a direction to wind up the ink ribbon when the winding shaft rotates in a direction opposite to the direction of feeding the ink ribbon to move the ink ribbon in the reverse direction; A printer having

2. The rotational force generating mechanism includes: a one-way bearing having a rotating member which rotates idly when the winding shaft rotates in the winding direction and rotates integrally with the winding shaft during backfeeding when the winding shaft rotates in the direction opposite to the winding direction; an elastic member that is elastically deformed by the rotation of the rotating member in the reverse direction and rotates the rotating member in the winding direction by a restoring force of the elastic member; The printer of claim 1 .

3. the elastic member is a tension spring having one end fixed to the rotating member and being stretched and wound around the rotating member when the rotating member rotates in the reverse direction; The printer of claim 2.

4. a pressing plate that is fixed to the rotating member and that, together with the rotating member, forms a holding groove around which the tension spring is wound while restricting its movement; The printer according to claim 3.

5. The other end of the tension spring is fixed to the pressing plate. The printer according to claim 4.

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