JP2015189578A - Sheet conveying device and printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet conveying device and a printer capable of correcting the skew of a sheet effectively by conveying the sheet in a normal direction and a reverse direction while suppressing the occurrence of deflection of the sheet.SOLUTION: A sheet conveying device 1 comprises: a first roller 21 rotated in a normal direction or a reverse direction; a second roller 22 for holding a rolled sheet between the first roller and conveying the sheet in the normal direction; a reverse conveying unit 2 for conveying the sheet in the reverse direction; and a separation mechanism for separating the second roller from the first roller by utilizing a driving force received from the first roller rotated in the reverse direction when the sheet is conveyed in the reverse direction by the reverse conveying unit.

Description

  The present invention relates to a sheet conveying device and a printer.

  2. Description of the Related Art A sheet conveying apparatus that conveys a roll-shaped sheet by two pairs of rollers is known. One of the two pairs of rollers is, for example, a main roller pair for paper conveyance, and the other is a roller pair for conveying the leading edge of the paper set in the housing of the apparatus to the main roller. Hereinafter, the latter roller pair is referred to as a loading roller pair. When setting a roll-shaped paper in such a paper transport device, for example, the user manually feeds the front end of the paper between the pair of loading rollers. In this case, since the leading edge of the roll paper is not necessarily sent straight, skew may occur in the conveyed paper. Therefore, in such a paper transport device, after a roll-shaped paper is set in the housing, an operation of correcting the skew by transporting the paper back and forth is executed.

  As described above, for example, those disclosed in Patent Documents 1 to 4 are known as techniques for a sheet conveying apparatus that suppresses or corrects skew (skew) that may occur when a sheet is conveyed using a pair of conveying rollers. ing. In Patent Document 1, when a sheet-like medium is transported in the forward direction and the reverse direction, one drive roller pair positioned on the downstream side in the transport direction is brought into a nip state and the other drive roller pair positioned on the upstream side is disclosed. Describes a medium conveying apparatus that conveys a sheet medium by driving one pair of driving rollers located on the downstream side.

  In Patent Document 2, a recording medium conveyed forward by a first roller and a second roller is sandwiched between a third roller and a fourth roller arranged in front of the conveying direction, and the first roller and the second roller A recording medium conveying method is described in which the recording medium is released by separating the recording medium and the recording medium is skewed by rotating the support shaft of the recording medium so that the recording medium is wound backward in the conveying direction.

  In Patent Document 3, a recording roller transports a starting end portion of a recording material to a feeding position downstream from a platen, switches a conveying driven roller to a release posture, releases a nip state of the conveying roller, and records the recording material. There is described a recording material transport device that performs skew removal of a recording material by rotating a rotating support member to be supported in a reverse direction and returning a starting end portion of the recording material to a stop position near the recording head.

  In Patent Document 4, when a skew is detected, the conveyance roller pair or the return roller pair that conveys with the roll paper interposed therebetween is released, and when the cancellation of the skew is detected, the conveyance roller pair or the return roller pair is released. An image forming apparatus that sandwiches roll paper is described.

JP 2013-060265 A JP 2011-057353 A JP 2008-254215 A Japanese Patent Laid-Open No. 04-256654

  Of the transport rollers described above, the main roller pair is configured to be able to contact and separate from each other. However, for example, one of the loading roller pairs is urged by a spring against the other roller and is always pushed against each other. It has been applied. Therefore, even if the sheet is transported back and forth between the two roller pairs, the movement of the sheet in the width direction is hindered by the loading roller pair, so that the effect of correcting skew is reduced. Further, when the paper is conveyed, if the paper is not sandwiched between the rollers to some extent, deflection may occur, and the leading edge of the paper may come off between the rollers.

  Therefore, the present invention provides a paper transport device capable of effectively correcting the skew of the paper by transporting in the forward direction and the reverse direction while suppressing the occurrence of paper deflection, as compared with the case without this configuration. An object is to provide a printer.

  The sheet conveying apparatus of the present invention is configured to convey a sheet in the forward direction by sandwiching a roll-shaped sheet between a first roller that is rotationally driven in the forward direction or the reverse direction and the first roller. A roller, a reverse conveyance unit that conveys the paper in the reverse direction, and a driving force received from the first roller that rotates in the reverse direction when the paper is conveyed in the reverse direction by the reverse conveyance unit. And a separation mechanism for separating the two rollers from the first roller.

  In the above-described paper transport device, it is preferable that the separation mechanism presses the second roller toward the first roller when transport in the reverse direction by the reverse transport unit is stopped.

  In the above-described sheet conveying apparatus, the separation mechanism is connected to the biasing member that biases the rotation shaft of the second roller so as to press the second roller against the first roller, and one end of the biasing member. A bar portion that receives the driving force from the first roller that rotates in the opposite direction and rotates the rod member so as to pull the biasing member against the biasing force of the biasing member; It is preferable to have a limiting member that limits rotation.

  In the above-described sheet conveying device, the limiting member is preferably a torque limiter that applies a torque equal to or less than a limit value set within a range overcoming the urging force of the urging member from the gear portion to the rod-shaped member.

  In the above-described paper transport device, it is preferable that the first roller and the second roller are rollers through which the leading end of a roll-shaped paper attached in the housing first passes.

  The printer of the present invention also includes a first roller that is rotationally driven in the forward direction or the reverse direction, and a second roller that sandwiches a roll-shaped sheet between the first roller and conveys the sheet in the forward direction. A roller, a reverse conveyance unit that conveys the paper in the reverse direction, and a driving force received from the first roller that rotates in the reverse direction when the paper is conveyed in the reverse direction by the reverse conveyance unit. A separation mechanism that separates the two rollers from the first roller, and a printing unit that is disposed downstream of the first roller and the second roller in the forward direction and prints on the conveyed paper.

  According to the above-described paper transport device and printer, it is possible to effectively correct the skew of the paper by transporting the paper in the forward direction and the reverse direction while suppressing the occurrence of paper deflection.

1 is a cross-sectional view illustrating a schematic configuration of a printer 1. FIG. 6 is a diagram for explaining the movement of the recording paper 10 in an initialization operation. FIG. 6 is a diagram for explaining the movement of the recording paper 10 in an initialization operation. 3 is a perspective view of a separation mechanism 40. FIG. FIG. 6 is a rear view of the separation mechanism 40 when the loading roller 21 is rotating forward. It is sectional drawing and the side view of the separation mechanism 40 at the time of forward rotation. FIG. 6 is a rear view of the separation mechanism 40 during the reverse rotation of the loading roller 21. It is sectional drawing and the side view of the separation mechanism 40 at the time of reverse rotation.

  Hereinafter, the sheet conveying device and the printer will be described with reference to the drawings. It should be understood, however, that the present invention is not limited to the drawings or the embodiments described below.

  FIG. 1 is a cross-sectional view illustrating a schematic configuration of the printer 1. In FIG. 1, only components necessary for explanation are shown in the components included in the printer 1, and other components are omitted.

  The printer 1 includes, as main components, a roll paper holder 2, a head 3, a supply side ribbon roller 4A, a take-up side ribbon roller 4B, a cutting unit 5, a platen roller 9, a ribbon guide roller 15, a grip roller 17, and a pinch roller. 18, a loading roller 21, an auxiliary roller 22, a discharge roller 23, and the like. Each of these components is arranged in the housing 7.

  The printer 1 reciprocates the roll-shaped recording paper 10 with respect to the head 3 to sequentially transfer, for example, a plurality of yellow, magenta, and cyan colors and an overcoat from the ink ribbon 4 onto the same area of the recording paper 10. The image is printed (printed). The printer 1 is an example of a paper transport device that transports roll-shaped paper. The printed recording paper 10 is cut by the cutting unit 5 and discharged to the outside of the printer 1 through the discharge port 6 provided on the front surface 12 of the printer 1. The material of the recording paper 10 is not particularly limited as long as it can be used for a printer.

  The roll paper holder 2 holds the recording paper 10 wound in a roll shape. The roll paper holder 2 is driven in the forward or reverse direction by the recording paper drive unit 32 and rotates around its central axis. As the roll paper holder 2 rotates in the forward direction, the recording paper 10 passes between the head 3 and the platen roller 9 and is conveyed toward the discharge port 6. Further, when the roll paper holder 2 rotates in the reverse direction, the recording paper 10 is rewound onto the roll paper holder 2. The roll paper holder 2 is an example of a reverse conveyance unit that conveys the paper in the reverse direction.

  Hereinafter, the conveyance direction when the recording paper 10 is sent out toward the discharge port 6 is referred to as “forward direction”, and the conveyance direction when the recording paper 10 is rewound onto the roll paper holder 2 is referred to as “reverse direction”. The rotation directions of the rollers that transport the recording paper 10 in the forward direction and the reverse direction are also referred to as “forward direction” and “reverse direction”, respectively.

  The supply side ribbon roller 4 </ b> A and the take-up side ribbon roller 4 </ b> B hold the ink ribbon 4. These rollers are driven by the ink ribbon drive unit 34 and rotate around their respective central axes. By this driving, the ink ribbon 4 is supplied from the supply side ribbon roller 4A, passes between the head 3 and the platen roller 9 via the ribbon guide roller 15, and is taken up by the take-up side ribbon roller 4B.

  The ink ribbon 4 is, for example, a belt-like sheet in which yellow, magenta, and cyan ink regions and an overcoat region are repeatedly arranged in the longitudinal direction in the same order. However, the ink ribbon 4 is not limited to such a sheet including a plurality of colors of ink, and may be a sheet including only a single color ink.

  The head 3 is configured to be movable with respect to the platen roller 9, and is pressed by the platen roller 9 with the ink ribbon 4 and the recording paper 10 sandwiched therebetween during printing. The head 3 is an example of a printing unit that prints on a sheet to be conveyed. When the head 3 generates heat, the color ink on the ink ribbon 4 and the overcoat are transferred onto the same area of the recording paper 10. This transfer is repeated for each area of the ink ribbon 4 while winding the ink ribbon 4. For the head 3, for example, a mechanism corresponding to the type of printer such as a sublimation type or a thermal melting type is used.

  The grip roller 17 and the pinch roller 18 are a pair of rollers that sandwich and convey the recording paper 10. The grip roller 17 is a main roller for paper conveyance. The grip roller 17 is rotationally driven in the forward direction or the reverse direction by the recording paper drive unit 32, and the pinch roller 18 is rotated by following the grip roller 17. There are innumerable protrusions on the surface of the grip roller 17, and the recording paper 10 is accurately conveyed by being stuck in the protrusions. The pinch roller 18 is movable with respect to the grip roller 17, and the pinch roller 18 opens and closes with the grip roller 17 by the movement of the pinch roller 18. The pinch roller 18 is pressed by the grip roller 17 when the recording paper 10 is conveyed and holds the recording paper 10 between the pinch roller 17 and is separated from the grip roller 17 when the recording paper 10 is not conveyed. The recording paper 10 is released. This is because the protrusion of the grip roller 17 moves to the pinch roller 18 when both rollers are in contact with each other without the recording paper 10 interposed therebetween.

  The loading roller 21 and the auxiliary roller 22 are also a pair of rollers that sandwich and convey the recording paper 10. The loading roller 21 and the auxiliary roller 22 serve to carry the leading end of the recording paper 10 to the grip roller 17 and the pinch roller 18 when the user sets the roll-shaped recording paper 10 in the roll paper holder 2. That is, the loading roller 21 and the auxiliary roller 22 are rollers through which the leading end of the roll-shaped recording paper 10 attached in the housing 7 passes first. The loading roller 21 is an example of a first roller, and is driven to rotate in the forward direction or the reverse direction by the recording paper drive unit 32. The auxiliary roller 22 is an example of a second roller, and rotates following the loading roller 21. The auxiliary roller 22 is biased by a spring with respect to the loading roller 21, but the recording paper 10 is conveyed in the reverse direction by a separation mechanism 40 (see FIGS. 4A and 4B) described later. When it is done, it is separated from the loading roller 21.

  The recording paper 10 that has passed between the head 3 and the platen roller 9 from the roll paper holder 2 passes through the discharge path 13 and is conveyed toward the discharge port 6 by the discharge roller 23. The cutting unit 5 cuts the recording paper 10 passing through the discharge path 13 and discharged from the discharge port 6 to the outside of the printer 1 at a position before the discharge port 6. The cutting unit 5 is driven by the cutting drive unit 35. The cutting part 5 is disposed immediately before the discharge port 6 on the discharge path 13.

  The printer 1 further includes a control unit 30, a data memory 31, a recording paper drive unit 32, a head drive unit 33, an ink ribbon drive unit 34, a cutting drive unit 35, and a communication interface 36.

  The control unit 30 is configured by a microcomputer including a CPU, a memory, and the like, and controls the overall operation of the printer 1. The data memory 31 is a storage area for accumulating image data received from the host computer via the communication interface 36.

  The recording paper drive unit 32 is a motor that drives the grip roller 17, the loading roller 21, and the roll paper holder 2. The recording paper drive unit 32 rotates the recording paper 10 either in the direction of feeding the recording paper 10 or in the direction of rewinding. The head drive unit 33 drives the head 3 based on the image data, and prints (prints) an image on the recording paper 10.

  The ink ribbon drive unit 34 is a motor that drives the supply side ribbon roller 4A and the take-up side ribbon roller 4B. The ink ribbon drive unit 34 and the take-up ribbon roller 4A take up the take-up ribbon roller 4A in either the direction in which the take-up ribbon roller 4B winds up the ink ribbon 4 or the direction in which the ink ribbon 4 is rewound onto the supply-side ribbon roller 4A. The side ribbon roller 4B is rotated.

  The cutting drive unit 35 is a motor that drives the cutting unit 5. The communication interface 36 receives image data to be printed from a host computer via a communication cable, for example.

  Next, an initialization operation for correcting the skew of the recording paper 10 executed when the user sets the roll-shaped recording paper 10 in the roll paper holder 2 will be described. 2A to 3E are diagrams for explaining the movement of the recording paper 10 in the initialization operation.

  First, a user pulls out a drawer portion (not shown) that is detachably stored in the housing 7 from the front surface 12 of the printer 1, and sets the roll-shaped recording paper 10 in the roll paper holder 2. 2A, the leading end 10E of the recording paper 10 is inserted between the loading roller 21 and the auxiliary roller 22, and the drawer is pushed into the housing 7.

  On the conveyance path of the recording paper 10, paper detection sensors 25A and 25B are provided. When the leading edge 10E of the recording sheet 10 is inserted between the loading roller 21 and the auxiliary roller 22, the leading edge 10E is first detected by the sheet detection sensor 25A on the upstream side of the transport path.

  Then, as shown in FIG. 2B, the recording paper 10 is conveyed in the forward direction by the loading roller 21 and the auxiliary roller 22 with the grip roller 17 and the pinch roller 18 being separated from each other. At this time, the ink ribbon 4 is slackened by rotating the supply-side ribbon roller 4A in the rewind direction and applying a rotation brake to the take-up ribbon roller 4B. The slack removal of the ink ribbon 4 is continued until the initialization operation is completed. Reference numeral 8 denotes a sensor for detecting the boundary of each ink region of the ink ribbon 4.

  When the leading edge 10E of the recording paper 10 passes between the grip roller 17 and the pinch roller 18, the pinch roller 18 is pressed against the grip roller 17 as shown in FIG. The recording paper 10 is held. The recording paper 10 is further conveyed in the forward direction by these rollers, and the leading edge 10E of the recording paper 10 is detected by the paper detection sensor 25B.

  Then, as shown in FIG. 3D, the recording paper 10 is conveyed to the discharge port 6 beyond the cutting portion 5 and is cut by a predetermined length by the cutting portion 5. After the cutting, as shown in FIG. 3E, the tip 10E of the recording paper 10 is moved to the paper detection sensor 25B by separating the pinch roller 18 from the grip roller 17 and rotating the roll paper holder 2 in the reverse direction. It is rewound to the position. At this time, the auxiliary roller 22 is separated from the loading roller 21 by a separation mechanism 40 described later so that the recording paper 10 can move in the width direction on the conveyance path. The feeding, cutting, and rewinding of the recording paper 10 shown in FIGS. 3D and 3E is repeated a plurality of times (for example, about 3 times).

  Thereafter, as shown in FIG. 3E, the recording paper 10 is conveyed by the grip roller 17 and the pinch roller 18 so that the leading end 10E comes to the retracted position downstream of the head 3, and stops at that position. Finally, the grip roller 17 and the pinch roller 18 are separated from each other, and the initialization operation ends. Thereafter, the printer 1 waits until the start of printing.

  4A and 4B are perspective views of the separation mechanism 40. FIG. The separation mechanism 40 is provided at a location where the loading roller 21 and the auxiliary roller 22 are disposed in the housing 7 so as to cover the auxiliary roller 22. 4A shows the separation mechanism 40 viewed from the loading roller 21 side, and FIG. 4B shows the separation mechanism 40 viewed from the side opposite to the loading roller 21. In the following description, the side of the loading roller 21 shown in FIG.

  The separation mechanism 40 separates the auxiliary roller 22 from the loading roller 21 using a driving force received from the loading roller 21 rotating in the reverse direction when the recording paper 10 is conveyed in the reverse direction by the roll paper holder 2. Further, the separation mechanism 40 presses the auxiliary roller 22 toward the loading roller 21 when conveyance in the reverse direction by the roll paper holder 2 is stopped. That is, the separation mechanism 40 creates a gap between the loading roller 21 and the auxiliary roller 22 only when the loading roller 21 is rotating backward. Hereinafter, the rotation in the forward direction and the rotation in the reverse direction are also simply referred to as “forward rotation” and “reverse rotation”, respectively.

  The separation mechanism 40 includes a paper guide frame 41, a loading spring 42, a loading shaft 43, a loading gear portion 44, and a torque limiter 45.

  The paper guide frame 41 has a slope 41A through which the recording paper 10 passes on the front side, and the slope 41A has two holes for protruding the auxiliary roller 22 upward. The paper guide frame 41 has a recess for accommodating the loading shaft 43 and the auxiliary roller 22 on the back side. The paper guide frame 41 holds the rotation shaft of the auxiliary roller 22 with the right side wall 41B and the left side wall (not shown).

  Both ends of the loading spring 42 are fixed to the paper guide frame 41 and the loading shaft 43 at the center on the back side of the paper guide frame 41. The loading spring 42 is an example of an urging member, and urges the rotation shaft of the auxiliary roller 22 so as to press the auxiliary roller 22 against the loading roller 21. That is, the loading spring 42 always presses the rotating shaft of the auxiliary roller 22 passing through the back side of the inclined surface 41 </ b> A of the paper guide frame 41 against the front side of the paper guide frame 41.

  The loading shaft 43 is an example of a rod-shaped member. Both ends of the loading shaft 43 are separated from the rotational axis of the auxiliary roller 22 on the back side of the paper guide frame 41, and the right side wall 41 </ b> B of the paper guide frame 41 and the back side of the paper guide frame 41. It is attached to the fixed part 41C which protrudes near the center of the side. The loading shaft 43 is rotatable about a rotation axis extending in the longitudinal direction, and rotates in the direction of arrow C2 when a driving force is transmitted from the loading gear portion 44, and rotates in the opposite direction when the transmission of the driving force is lost. Return to the angle. However, the rotation angle of the loading shaft 43 is limited within a certain range by the fixing portion 41C and the torque limiter 45, as will be described later. The loading shaft 43 has a protrusion 43A at the lower end of the position corresponding to the loading spring 42 attached to the paper guide frame 41 in the longitudinal direction. One end of a loading spring 42 is connected to the protrusion 43A.

  The loading gear portion 44 includes a loading gear 44A and a loading gear 44B that are meshed with each other, and these are respectively attached to the rotation shaft of the loading roller 21 and the rotation shaft of the loading shaft 43 on the right side of the paper guide frame 41. Yes. The loading gear 44A is connected to a gear (not shown) that rotates the roll paper holder 2 via another gear (not shown). Thus, the loading gear 44A receives the driving force from the motor of the recording paper driving unit 32 via the roll paper holder 2 and rotates the loading roller 21 in the forward direction or the reverse direction.

  The loading gear 44A and the loading gear 44B rotate in the directions of the arrow A2 and the arrow B2 respectively when the loading roller 21 rotates backward, and rotate in the opposite direction when the loading roller 21 rotates forward. In particular, the loading gear 44B rotates the loading shaft 43 in the direction of the arrow C2 when the loading roller 21 rotates backward. That is, the loading gear portion 44 receives the driving force from the loading roller 21 rotating in the reverse direction, and rotates the loading shaft 43 so as to pull the loading spring 42 against the urging force of the loading spring 42.

  The torque limiter 45 is an example of a limiting member, and is attached between the loading gear 44 </ b> B and the loading shaft 43 on the rotation shaft of the loading shaft 43. When the loading gear 44B rotates in the direction of the arrow B2, when the loading shaft 43 rotates to some extent in the direction of the arrow C2 against the biasing force of the loading spring 42, the torque limiter 45 idles the loading gear 44B to drive further. The force is prevented from being transmitted from the loading gear 44B to the loading shaft 43. When the loading gear 44B rotates in the direction opposite to the arrow B2 direction, the torque limiter 45 idles the loading gear 44B from the beginning so that the driving force is not transmitted from the loading gear 44B to the loading shaft 43. That is, the torque limiter 45 limits the rotation of the loading shaft 43 by applying a torque equal to or less than a limit value set within a range overcoming the urging force of the loading spring 42 from the loading gear portion 44 to the loading shaft 43.

  FIG. 5 is a rear view of the separation mechanism 40 when the loading roller 21 is rotating forward. 6A to 6D are respectively a cross-sectional view taken along line AA and a cross-sectional view taken along line BB in FIG. 5, and a right side view and a left side view of the separation mechanism 40 during normal rotation. It is.

  During normal rotation, the loading roller 21 rotates in the direction of the arrow A1 together with the loading gear 44A. At this time, since the loading spring 42 presses the rotating shaft 22 </ b> A of the auxiliary roller 22 against the loading roller 21, the auxiliary roller 22 protrudes from the inclined surface 41 </ b> A of the paper guide frame 41 and contacts the loading roller 21. For this reason, the auxiliary roller 22 is driven by the loading roller 21 and rotates in the arrow B1 direction. During the normal rotation of the loading roller 21, the loading gear 44 </ b> B rotates idly by the torque limiter 45, so that the driving force of the loading gear portion 44 is not transmitted to the loading shaft 43, and the rotation of the auxiliary roller 22 is prevented by the loading shaft 43. Absent.

  6B, the loading shaft 43 is in contact with the fixed portion 41C of the paper guide frame 41 at the rotating shaft 43B and the contact 43C, and the contact 43C is a fixed portion when the loading shaft 43 rotates. It can slide in the groove 41D provided in 41C. When the loading shaft 43 is pressed against the loading roller 21 by the loading spring 42 connected to the protrusion 43A, the contact 43C slides to the front side (slope 41A side) of the separation mechanism 40 in the groove 41D. When the contact 43C contacts the end portion on the front side of the separation mechanism 40 in the groove 41D, further rotation of the loading shaft 43 is prevented. Therefore, the loading shaft 43 stops at an angle shown in FIG. 6B while being inclined in the direction of the arrow C1.

  Even when the loading roller 21 is stopped, the auxiliary roller 22 and the loading shaft 43 are in the same positions as those in the normal rotation shown in FIGS. 6 (A) to 6 (D), and the auxiliary roller 22 contacts the loading roller 21. Touch.

  FIG. 7 is a rear view of the separation mechanism 40 during the reverse rotation of the loading roller 21. 8A to 8D are a cross-sectional view taken along the line CC of FIG. 7, a cross-sectional view taken along the line DD, and a right side view and a left side view of the separation mechanism 40 during the reverse rotation, respectively. It is.

  At the time of reverse rotation, the loading roller 21 rotates in the direction of the arrow A2 together with the loading gear 44A. At this time, the loading gear 44B rotates in the arrow B2 direction and transmits the driving force to the loading shaft 43 via the torque limiter 45, thereby rotating the loading shaft 43 in the arrow C2 direction. As a result, the loading spring 42 is pulled on the back side of the paper guide frame 41, and the rotating shaft 22A of the auxiliary roller 22 fixed to the loading spring 42 also moves away from the inclined surface 41A together with the loading spring 42. For this reason, the auxiliary roller 22 falls into a hole provided in the inclined surface 41 </ b> A of the paper guide frame 41 and is separated from the loading roller 21. Since the auxiliary roller 22 is a roller that rotates following the loading roller 21, the auxiliary roller 22 stops when the loading roller 21 rotates backward.

  Further, as shown in FIG. 8B, when the loading shaft 43 rotates in the direction of the arrow C2, the contact 43C of the loading shaft 43 in the fixing portion 41C is connected to the back side (slope 41A) of the separation mechanism 40 in the groove portion 41D. Slide to the opposite side. When the contact 43C contacts the end portion on the back side of the separation mechanism 40 in the groove 41D, further rotation of the loading shaft 43 is prevented. Therefore, the loading shaft 43 stops at an angle shown in FIG. 8B while being inclined in the direction of the arrow C2. At the time of reverse rotation of the loading roller 21, when a torque is applied to rotate the loading shaft 43 to the angle shown in FIG. 8B against the urging force of the loading spring 42, the loading gear 44 B is idled by the torque limiter 45. . Therefore, only a certain amount of driving force necessary to separate the auxiliary roller 22 from the loading roller 21 is transmitted to the loading shaft 43.

  When the reverse rotation of the loading roller 21 is stopped, the loading shaft 43 returns to the original position even when the loading shaft 43 is rotated in the direction of the arrow C1 by the action of the loading spring 42. For this reason, the auxiliary roller 22 protrudes again from the inclined surface 41A of the paper guide frame 41 and contacts the loading roller 21 as shown in FIGS. 6 (A) to 6 (D).

  As described above, in the printer 1, the auxiliary roller 22 is separated from the loading roller 21 by the separation mechanism 40 when the roll-shaped recording paper 10 is rewound onto the roll paper holder 2. Thus, the recording paper 10 is sandwiched between the loading roller 21 and the auxiliary roller 22 when transported in the forward direction, and is released between the loading roller 21 and the auxiliary roller 22 when transported in the reverse direction. Accordingly, during the initialization operation in which the recording paper 10 is transported in the forward and reverse directions without printing, the recording paper 10 can move in the width direction only when transporting in the reverse direction. The correction effect is improved. Therefore, even if the recording paper 10 is set obliquely, the printer 1 is prevented from being printed obliquely on the recording paper 10.

  Further, when the reverse rotation of the loading roller 21 stops, the operation of the separation mechanism 40 disappears, and the auxiliary roller 22 comes into contact with the loading roller 21 again. That is, since the loading roller 21 and the auxiliary roller 22 are closed except during the conveyance in the reverse direction, the original functions of the loading roller 21 and the auxiliary roller 22 that hold the recording paper 10 and convey it in the forward direction. Is not affected by the separation mechanism 40. For this reason, in the printer 1, it is possible to prevent the recording paper 10 from being bent due to the opening between the loading roller 21 and the auxiliary roller 22, and the leading edge of the recording paper 10 from being displaced from between these rollers.

  Note that the function of separating the auxiliary roller 22 during the reverse rotation of the loading roller 21 is not limited to the separation mechanism 40 described above, and can be realized, for example, by directly attaching a torque limiter and a cam to the rotation shaft of the loading roller 21. Further, a motor or the like may be added separately, and the driving force may be used to open and close between the loading roller 21 and the auxiliary roller 22. Further, the loading roller 21 and the auxiliary roller 22 may be opened and closed in conjunction with the operations of the grip roller 17 and the pinch roller 18.

  The separation mechanism described above is not limited to a printer that uses the ink ribbon 4 as in the printer 1 as long as it uses roll paper. It is also applicable to the device.

DESCRIPTION OF SYMBOLS 1 Printer 2 Roll paper holder 3 Head 10 Recording paper 17 Grip roller 18 Pinch roller 21 Loading roller 22 Auxiliary roller 40 Separating mechanism 42 Loading spring 43 Loading shaft 44 Loading gear part 45 Torque limiter

Claims (6)

A first roller that is rotationally driven in the forward or reverse direction;
A second roller that sandwiches a roll-shaped sheet with the first roller and conveys the sheet in the forward direction;
A reverse conveyance unit for conveying the paper in the reverse direction;
When the paper is transported in the reverse direction by the reverse transport unit, the second roller is moved from the first roller by using a driving force received from the first roller rotating in the reverse direction. A separating mechanism for separating;
A sheet conveying apparatus comprising:   The sheet conveying device according to claim 1, wherein the separation mechanism presses the second roller toward the first roller when conveyance in the reverse direction by the reverse direction conveyance unit stops. The separation mechanism is
An urging member that urges the rotation shaft of the second roller so as to press the second roller against the first roller;
A rod-like member to which one end of the biasing member is connected;
A gear portion that receives the driving force from the first roller rotating in the reverse direction and rotates the rod-like member so as to pull the biasing member against the biasing force of the biasing member;
A limiting member for limiting the rotation of the rod-shaped member;
The sheet conveying apparatus according to claim 2, comprising:   The sheet conveying device according to claim 3, wherein the limiting member is a torque limiter that applies a torque equal to or less than a limit value set in a range overcoming the urging force of the urging member from the gear portion to the rod-shaped member.   The sheet conveying device according to any one of claims 1 to 4, wherein the first roller and the second roller are rollers through which a leading end of a roll-shaped sheet attached in a housing passes first. . A first roller that is rotationally driven in the forward or reverse direction;
A second roller that sandwiches a roll-shaped sheet with the first roller and conveys the sheet in the forward direction;
A reverse conveyance unit for conveying the paper in the reverse direction;
When the paper is transported in the reverse direction by the reverse transport unit, the second roller is moved from the first roller by using a driving force received from the first roller rotating in the reverse direction. A separating mechanism for separating;
A printing unit that is arranged on the downstream side in the forward direction from the first roller and the second roller and prints on the conveyed paper;
A printer comprising:

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