JP2006248683A - Sheet conveying device and recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet conveying device and a recording device capable of conveying a roll-like sheet always with high accuracy and performing always stable image recording without causing enlargement and complication of the devices. <P>SOLUTION: A shaft part 11c of a spool 11 holding the roll-like sheet Pr wound thereon and rotatable in a delivering direction and a rewinding direction is provided with a rotating load means 75, and unidirectional transmitting means 14a (81, 82) for transmitting only driving in the rewinding direction without transmitting driving in the delivering direction of the roll sheet Pr are provided in a gear train 14 for transmitting driving from a drive source 60 (80) to the rotating load means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sheet conveying apparatus for feeding and conveying a roll-shaped sheet wound and held on a spool to an image forming area such as a printer, and a recording apparatus including the sheet conveying apparatus.

A printer that records an image on a recording medium based on image information, a recording device such as a copying machine or a facsimile, a composite device to which other functions such as a printer function, a facsimile function, a document reading function, or an imaging function are added; A system apparatus configured by connecting a recording apparatus to a host machine such as a computer is used. One form of a recording apparatus used in these apparatuses is one that forms an image on a sheet such as a roll-shaped recording paper or a film. In such a recording apparatus, a sheet conveying apparatus for feeding and conveying the sheet from a roll holder portion that holds a roll-shaped sheet to an image forming area is used. Incidentally, "sheet" in this application is intended to refer to a recording medium, the material is limited to the paper or plastic sheet [field] no.

  FIG. 8 is a schematic longitudinal sectional view illustrating a conventional configuration of a recording apparatus that handles a roll-shaped sheet. In FIG. 8, the recording apparatus includes a rotatable roll holder 110 that winds and holds a roll-shaped sheet (hereinafter also referred to as roll paper) Pr that is a recording medium, and roll paper that is sent out and conveyed. An image forming unit 120 that forms an image while guiding and holding, and a paper discharge unit 130 that discharges the roll paper on which the image is formed to the outside of the apparatus are provided. The roll holder 110 includes a rotatable spool 111 that holds the roll paper so as to be fed out, and flanges 112 for guiding the side edges of the roll paper are provided on both sides of the spool. A rotation load means (tor limiter) 113 is provided at one end of the spool 111. A leaf spring (not shown) is attached to the left end portion of the spool 111 to perform backlash in the thrust direction.

  The torque limiter 113 includes a fixed part on the spool 111 side and a co-rotating part that rotates integrally with the spool until the transmission torque reaches a predetermined value, and the roll paper Pr on the spool 111 rotates (sends and winds). A predetermined rotational load (load torque) Tr is generated when the return is performed. This torque is generally called a roll brake T. A constant tension (tension) T is applied to the roll paper between the roll holder 110 and the LF roller (conveyance roller) 121 by the roll brake T. With this tension T, it is possible to correct the skew of the roll paper, and to remove deviations and slacks when the user loads the roll paper. The roll brake T is calculated by “T = Tr (rotational load) / (roll diameter φD / 2)”. In the present embodiment, the load torque Tr of the rotational load means 113 is, for example, about 0.8 to about 1.5 kgf. It is set to about cm.

In order to feed and convey the roll paper Pr, a paper feed roller 115 and a plurality of driven rollers 116 urged by the roller with a predetermined pressure are provided. The paper feed roller 115 is driven by a paper feed motor (not shown). The image forming unit 120 includes a conveyance roller (LF roller) 121 for conveying a predetermined amount of roll paper at the time of recording, a plurality of pinch rollers 122 that are driven and rotated by the conveyance roller with a predetermined pressure F, and a sheet. A suction platen 123 for sucking and holding it in a planar shape, a recording head 141 for recording based on image information, and a carriage mounted with the recording head and capable of reciprocating in a direction crossing the transport direction (main scanning direction) 140.
JP 2003-12205 A JP 2001-163495 A

  However, in the above-described conventional configuration, when the roll paper Pr is set and fed (pre-feed), a constant tension T is applied between the paper feed roller 115 and the roll holder 110 when the roll paper is conveyed in the forward direction. However, when the sheet is conveyed in the reverse direction (rewinding direction), as shown by the chain line in FIG. The recording operation is started from this state. When the recording operation is started and the loop disappears, the roll brake T acts. For this reason, roll paper slip occurs at the nip of the conveying roller 121 (the pressing and clamping portion of the pinch roller 122), and the amount of roll paper fed decreases.

  Since the feed amount of the sheet changes due to the ON / OFF of the roll brake caused by such a loop, it causes image defects such as a density difference in the recorded image and uneven stripes (black stripes, white stripes). In particular, in a configuration in which a cutter is provided in the apparatus main body and the roll paper is cut and ejected, a paper returning operation (back feed) is performed every time. Such image defects may occur. Further, as described above, when a leaf spring (not shown) biased in the axial direction is used to loosen the spool 111 in the thrust direction, the load in the spool rotation direction further increases, It will encourage the slip.

  Furthermore, as the roll paper Pr is wider or the mass is increased due to a larger roll diameter, it is necessary to increase the suppression force in the thrust direction of the spool, and as a result, the load due to the leaf spring increases. In the illustrated example, the feeding (feeding) and rewinding of the roll paper is controlled by the paper feed roller 115 and the driven roller 116. However, such a configuration has not only a complicated mechanism but also a paper feed. A costly mechanism such as the paper roller 115, the paper feed roller stay 117 that holds the roller, the driven roller 115, and the driven stay 118 that holds the roller is necessary. Furthermore, this configuration further increases the cost including the cost of the paper feeding roller 115 and the strength of each stay, such as an increase in the size of the apparatus.

  The present invention has been made in view of such a technical problem, and an object of the present invention is to always convey a roll-shaped sheet with high accuracy without causing an increase in size and complexity of the apparatus. Another object of the present invention is to provide a sheet conveying apparatus capable of always performing stable image recording and a recording apparatus using the conveying apparatus.

In order to achieve the above object, a sheet conveying apparatus according to the present invention holds a roll-shaped sheet and is rotatable in a sending-out direction and a rewinding direction, a conveying unit that conveys the sheet through an image forming area, A rotational load means for applying a predetermined rotational load to the spool, and the rotational load means is provided in a shaft portion of the spool, and the gear train for transmitting the drive to the rotational load means includes: One-way transmission means is provided for transmitting the driving in the rewinding direction without transmitting the driving in the sheet feeding direction.
In order to achieve the above object, a recording apparatus according to the present invention is characterized in that the recording apparatus for forming an image on a roll sheet based on image information includes the sheet conveying apparatus having the above-described configuration.

  According to the present invention, in the gear train for transmitting the drive to the rotary load means mounted on the shaft portion of the spool, the drive in the direction of feeding the roll sheet is not transmitted, but the drive in the rewinding direction is transmitted. Since a one-way transmission means is provided, a roll brake can be applied during the conveyance of a roll-shaped sheet and a rewinding torque can be transmitted during rewinding with a simple and inexpensive configuration. Also, the roll brake can be applied to eliminate sheet slack, so that the conveyance disturbance in the recording operation can be eliminated, the roll sheet can be conveyed with high accuracy, and stable and high-quality image recording can be realized. A sheet conveying apparatus and a recording apparatus are provided.

  Embodiments of the present invention will be specifically described below with reference to the drawings. Note that the same reference numerals denote the same or corresponding parts throughout the drawings. FIG. 1 is a schematic perspective view showing an embodiment of a recording apparatus provided with a sheet conveying apparatus according to the present invention, and FIG. 2 is a schematic longitudinal sectional view of the recording apparatus of FIG. 1 and 2, a recording apparatus (image forming apparatus) 1 includes a roll holder portion 10 for rotatably winding and holding a roll sheet (also referred to as roll paper) Pr as a recording medium, and the roll An image forming unit 20 that records an image on roll paper Pr that is fed and conveyed from the holder unit, and a paper discharge unit 30 that discharges the image-formed sheet to the outside of the apparatus main body.

  FIG. 3 shows a first embodiment of a sheet conveying apparatus according to the present invention, that is, a first embodiment of a driving mechanism of a sheet conveying apparatus for feeding and conveying a roll-shaped sheet Pr wound around a spool 11. It is a typical perspective view which shows the principal part. 1 to 3, the roll holder portion 10 has a rotatable spool 11 having flanges 12L and 12R on both sides, and the roll 11 is rolled in a state in which the position in the width direction is regulated by the flanges 12L and 12R. Paper Pr is wound. Both ends of the spool 11 are rotatably supported by bearings 13L and 13R. In order to facilitate replacement of the roll paper, slide slopes 13'L and 13'R are provided in front of the bearings 13L and 13R, and the user can roll paper Pr along the slope. Remove and replace (replace).

  At the set position (loading state) of the roll paper Pr, the conveyance motor (LF motor) 60 is driven via the gear train 14 with respect to the rotation load means (torque limiter) 11c provided at the left end of the spool 11. It is configured to be able to communicate. The transport motor 60 is essentially for driving the transport roller 21, and the roll paper Pr is transported in the forward direction and the reverse direction by rotating the transport roller 21 forward and backward by forward and reverse rotation of the motor. Is possible. A lower guide 15 serving as a guide (or support) when the user feeds the leading end of the roll paper Pr to the image forming unit 20 is disposed below the roll paper Pr to be sent out. An upper guide 16 is provided at a position facing the lower guide.

  The image forming unit 20 includes a conveying roller 21 for intermittently feeding the roll paper Pr at a predetermined pitch when recording, and a plurality of pinch rollers 22 that are driven to rotate by contacting the conveying roller with a predetermined pressing force. The suction platen 23 for guiding and supporting the recording medium in a flat shape while sucking the recording medium and the recording head 41 are mounted in a direction (X direction, main scanning direction) intersecting the transport direction (Y direction, sub-scanning direction). A reciprocally movable carriage 40. The roll-shaped sheet (roll paper) Pr indicates a recording medium, and the material thereof is not limited to paper or a plastic sheet.

  First, the carriage 40 on which the recording head 41 is mounted will be described. In this embodiment, an ink jet recording head 41 is mounted on the carriage 40. By driving the recording head 41 based on the image data in synchronization with the main scanning movement of the carriage 40, ink is ejected from the ejection port (ejection port array) of the recording head toward the recording paper Pr, and the image is recorded. To form. A pair of parallel main rails 51 and sub rails 52 are fixed to a main stay 50 arranged in the main scanning direction on the apparatus main body, and the carriage 40 reciprocates along the rails 51 and 52 via bearings 42 and 43. Guided support is possible. In this embodiment, the case where the recording apparatus 1 is an ink jet recording apparatus is illustrated, but the recording apparatus 1 uses recording means of other forms such as a laser beam type, a thermal transfer type, a thermal type, and a wire dot type. It may be a recording device.

  The bearings 42 and 43 are provided at predetermined intervals in the front and rear direction of the carriage 40, and one (rear) bearing 43 is attached to the carriage 40 so as to be slidable in the front and rear direction. A spring 43a is mounted between the carriage 40 and the bearing 43, and the bearing 43 is pressed against the sub rail 52 by the biasing force of the spring. With such a configuration, the carriage 40 is always urged toward the main rail 51, and the recording head 41 is prevented from being shaken due to the vibration of the carriage 40 or the looseness of the bearing in the recording operation. This enables high-quality image formation.

  A linear sensor 44 is mounted on the upper portion of the bearing 43 of the carriage 40. This linear sensor reads an optical linear scale 53 attached to the main stay 50 so as to extend in the main scanning direction. With this reading signal, drive control of the carriage 40 and image generation control of the recording head 41 are performed. The carriage 40 is moved by transmitting a drive of a carriage motor (not shown) provided near one end of the main stay 50 via the carriage belt 54. In this way, in synchronization with the movement of the carriage 40, the recording head 41 is driven based on the image data, thereby forming an image on the roll paper Pr.

  Next, the conveyance roller 21, the pinch roller 22, the suction platen 23, and the like will be described with reference to FIGS. 1 to 3, the transport roller 21 transports a predetermined amount of roll paper during each main scan by the recording head 41, but the transport accuracy greatly affects the image quality. Therefore, the conveying roller 21 can finish the outer diameter dimension, centering, and the like with high accuracy. The peripheral surface of the transport roller 21 is sandblasted or coated with ceramic powder to increase the coefficient of friction so that the roll paper Pr being transported is prevented from slipping. The conveyance roller 21 is driven by a conveyance motor 60 connected to one side end.

  The pinch roller 22 is rotatably held by a pinch roller arm 22a, and is pressed against a conveying roller (LF roller) 21 by a pinch roller spring 22b at the rear thereof, and these are unitized by a pinch roller holder 22c. . A plurality of pinch roller holders 22 c arranged in the moving direction of the carriage 40 are attached to the main stay 50. A plurality of bearings 24 that rotatably hold the conveying roller 21 are arranged on a lower stay 25 of a sealed cavity structure. A paper feed sensor 26 for detecting the leading edge or the trailing edge of the recording medium (roll paper) Pr is disposed on the upstream side of the conveying roller 21 in the conveying direction.

  A suction platen 23 having a plurality of suction holes 23a is attached to the upper surface of the lower stay 25 extending in the width direction of the apparatus main body. A suction fan 70 is connected to one end of the lower stay 25 of the sealed cavity structure. By operating the suction fan 70, suction is performed from the suction hole 23 a of the platen 23 using the lower stay 25 as a suction duct, and the roll paper Pr is sucked onto the platen 23. This prevents paper floating during recording, undulation (cockling) after recording, and the like.

  FIG. 4 is a longitudinal sectional view showing the structure of a part of the spool 11 in FIGS. 1 to 3 and the rotational load means (torque limiter) 75 mounted on the shaft portion of the spool. 1 to 4, the roll-shaped sheet Pr is rotatably held by a spool 11 and flanges 12L and 12R on both sides. One flange 12L is slidable along the spool 11, and the width direction position of the roll paper Pr is regulated by the flange 12L. The shaft 11c at both ends of the spool 11 is provided with a bearing 11a. The spool 11 is rotatably supported by supporting the bearings 11a and 11a on both sides with the left and right U-grooves 13L and 13R.

  In FIG. 4, a rotation load means 75 is attached to the left shaft portion 11 c of the spool 11 by a parallel pin 11 b, and the rotation load means 75 is configured to rotate together with the spool 11. The rotational load means 75 can transmit a rotational force (torque) that is less than or equal to a predetermined value regardless of the direction of rotation. It will function. The rotational load means 75 of this embodiment is of a type that generates a predetermined load torque Tr when either the outer diameter projection 75a or the inner diameter groove 75b is stopped rotating. In this example, this torque The value of Tr is 1.0 to 1.5 kgf. It is set to cm. As will be described later, the torque value Tr is used to generate a roll brake T for feeding the roll paper Pr and to generate a winding torque for rewinding.

By applying a certain tension (roll brake) T between the roll paper Pr and the transport roller 21, the skew of the roll paper Pr can be corrected, thereby causing a deviation that occurs when the user rolls the roll. In addition to removing slack and slack, and applying a certain load to the roll paper Pr, stable and highly accurate conveyance can be realized. The roll brake T is calculated by the following equation.
Roll brake T = rotational load means torque Tr / (roll diameter φD / 2)
The protrusion 75a of the rotation load means 75 and the groove 75d inside the housing 75c are fitted. A gear 75e is provided at the left end of the housing 75c. When the roll paper Pr is set in the apparatus main body 1, the gear 75e is connected to the gear train 14 for driving the roll.

  FIG. 5 is a schematic diagram showing the principle of the rotational load means 75. The rotation load means 75 generates a predetermined load torque in the rotation direction (both forward and reverse directions) of the spool 11 with one side being prevented from rotating. In FIG. 5, the outer diameter surface of the shaft portion 11c of the spool 11 and the inner diameter surface of the gear 75e of the rotation load means 75 are rotatably fitted, and concave portions 75i formed at a plurality of locations on the outer diameter surface of the shaft portion 11c. Each of these is loaded with an elastic member 75g made of a leaf spring or a disc spring. Each elastic member 75g is loaded in a state where it is elastically displaced by a predetermined amount. According to the mechanism shown in FIG. 5, the inner diameters of the elastic member 75g and the gear 75e when the rotational force (torque) acting on the shaft portion 11c or the gear 75e is equal to or less than a predetermined value regardless of the transmission direction and the rotation direction of the rotation. Relative rotation is stopped by the frictional force with the surface, and if one is stopped, the other will not rotate. On the other hand, when the rotational force acting on the shaft 11c or the gear 75e is equal to or greater than a predetermined value, regardless of the rotation transmission direction and the rotation direction, even if one of the rotation is stopped, the other is the elastic member 75g and the gear 75e. It will rotate by overcoming the frictional force between it and the inner surface.

  The gear train 14 is for transmitting drive to the rotational load means 75, and a one-way gear 14a as a one-way transmission means is provided (connected) in the gear train 14. In the present embodiment, the one-way gear 14a is disposed in the vicinity of the roll paper Pr of the roll driving gear train 14. The one-way gear 14a is provided in the shaft portion of the spool 11 by being configured so that the spool 11 is fixed in the forward rotation direction in which the sheet Pr is sent out and is free in the reverse rotation direction in which the spool 11 rewinds the sheet Pr. The unidirectional transmission means is configured to transmit the driving in the rewinding direction to the rotating load means (torque limiter) 75 without transmitting the driving in the sheet feeding direction.

  FIG. 6 is a schematic diagram showing the principle of the one-way gear 14a as one-way transmission means. In FIG. 6, the inner diameter surface of the gear 14a and the outer diameter surface of the shaft portion 77a are rotatably fitted, and wedge-shaped grooves 77b are formed at a plurality of positions on the outer diameter surface of the shaft portion 77a. A ball 77c is loaded inside 77b. For the rotation of the gear 14a in the direction of arrow A, the ball 77c is locked inside the groove 77b, so that the gear 14a is fixed (locked), and drive transmission through the gear 14a is not performed. On the other hand, with respect to the rotation of the gear 14a in the direction of arrow B, the ball 77c becomes free inside the groove 77b, so that the gear 14a can freely rotate, and drive transmission is performed via the gear 14a.

  The drive of the transport motor 60 is transmitted to the gear train 14 via the transport belt 61, the transport pulley 62, the transport gear 63, the drive belt 64, and the drive pulley 65. An electromagnetic clutch 66 is provided coaxially with the drive pulley 65. The electromagnetic clutch 66 turns on / off transmission of rotational drive, and the drive of the transport motor 60 is transmitted to the gear train 14 only when the clutch is turned on. The electromagnetic clutch 66 is turned on when the roll paper Pr is rewound (reversed).

  Here, the onway gear 14a is free (in a rotatable state) in the reverse direction in which the spool 11 rewinds the roll paper Pr. For this reason, when the transport roller 21 is driven in the return direction (reverse feed direction, reverse direction), the electromagnetic clutch 66 is turned on, and the roll paper Pr is driven in the rewind direction via the gear train 14 and the rotation load means 75. Is done. That is, since the one-way gear 14 a becomes free in the rewind direction, the drive from the transport motor 60 is transmitted to the spool 11 via the electromagnetic clutch 66, the gear train 14, and the rotational load means 75. The drive (rotational torque) transmitted to the spool 11 is a roll paper rewinding torque determined by the rotational load means 75.

  On the other hand, the one-way gear 14a is fixed (locked) in the direction in which the spool 11 feeds the roll paper Pr (forward rotation direction). That is, when the conveying roller 21 is driven in the feeding direction (conveying direction, normal rotation), the electromagnetic clutch 66 is turned off and the one-way gear 14a is fixed (locked), and the drive is not transmitted to the rotational load means 75. For this reason, the rotation load means 75 (the side connected to the gear train 14) is in a rotation-stopped state. Accordingly, when the roll paper Pr is fed forward (conveyed) during the recording operation or the like, the predetermined load torque (roll brake) T is applied to the roll paper Pr by the rotational load means 75. To do. As is clear from the above, the torque limiter (rotational load generating means) 75 constitutes a roll brake (back tension, load torque) generating means when the roll paper is fed and a rewinding torque generating means when the roll paper is rewound. ing.

  Since the on / off timing of the electromagnetic clutch 66 is selected so as to be turned on in one-direction rotation (rotation in the reverse direction of the roll), a one-way clutch or a pendulum gear (normal position) is used instead of the electromagnetic clutch 66. (E.g., escape by a spring during rotation, and a gear is connected by the rotational force during reverse rotation). If such a one-way clutch or a pendulum gear is used, no electrical parts are used, so that the manufacturing cost can be further reduced and a highly reliable sheet conveying apparatus with few failures can be obtained.

  Here, regarding the rewinding of the roll paper Pr, the peripheral speed of the roll paper even when the roll paper has a minimum diameter (core side) with respect to the rewind speed (reverse rotational peripheral speed) V of the transport roller 21. V ′ is set to be about 30% faster. This setting can be made according to the specifications of the drive pulley 65 and the gear train 14. With such a configuration, when the roll paper Pr rotates normally (when feeding or transporting), the rotation load means (torque limiter) 75 acts as the roll brake T, and when the roll paper Pr is reversed (rewinding). ), A function can be obtained as a rotational force generating means for generating a rotational force (torque) necessary for unwinding while absorbing the fluctuation of the unwinding speed V ′ due to the outer diameter ΦD of the roll paper.

Further, since the rotational load means 75 for generating a predetermined load torque is provided coaxially with the roll paper Pr (spool 11), an efficient sheet conveying apparatus with little transmission loss can be obtained. Accordingly, a very simple roll rewind drive configuration can be obtained without complicating the roll rewind drive configuration, and the following effects can be obtained.
That is, the roll paper Pr has a plurality of types of inner diameters of the winding (paper winding) depending on the basis weight, thickness, or rigidity. For example, in the case of a thin and low-rigidity roll paper, the 2-inch paper winding (inner diameter ΦD = 50. 8 mm) is used, and in the case of a thick and high-rigidity roll paper, a 3-inch paper roll (inner diameter ΦD = 76.2 mm) is used. In this embodiment, roll paper of 2 inch paper roll is used, but in the case of 3 inch paper roll, the value of the roll brake is increased depending on the size of the outer diameter and the characteristics (high rigidity, high weight) of the roll paper. There is a need. At the same time, it is necessary to increase the torque value required for roll rewinding.

  Such a case can be dealt with by merely increasing the value of the set torque of the rotational load means 75. In this embodiment, the value of the set torque is 3.0 to 4.0 kgf. cm is selected. Further, even when the paper width is wide, it can be dealt with by optimizing the torque value of the rotational load means 75 in the same manner. In other words, according to the present embodiment, the necessary roll brake value and the necessary rewinding torque value are in a proportional relationship, so the paper width, the roll outer diameter, etc. can be changed only by changing the set value of the rotational load means (torque limiter). Therefore, it is possible to provide a very simple and inexpensive sheet conveying apparatus.

  Next, the paper feed conveyance operation of the roll paper Pr in the above configuration will be described. 1 to 4, the user first sets the roll paper Pr in the main body 1 of the recording apparatus, inserts the leading end of the roll paper between the lower paper feed guide 15 and the upper paper feed guide 16, and moves the upper and lower sides as they are. The feeding operation is performed while guiding with the guide pairs 15 and 16. When the leading edge of the roll paper Pr hits the nip portion of the transport roller 21, the feed is detected by a paper feed sensor 26 arranged on the upstream side (near side) of the roll paper Pr. The forward rotation (feed rotation) is started and the roll paper Pr is picked up. Following the pickup operation, the roll paper is temporarily stopped when a predetermined amount has been conveyed, and the user is notified of the roll paper Pr set. In response to this, the user once releases the nip of the pinch roller 22 and turns on the nip of the pinch roller 22 with the right end of the roll paper aligned with the set line.

  Next, in response to the nip-on signal of the pinch roller 22, the roll paper Pr is conveyed in the forward direction by a predetermined amount (for example, 300 to 400 mm). At this time, the set deviation such as the skew of the roll paper is corrected by the action of the roll brake T. A conveyance operation for correcting such a set deviation is called a pre-feed operation. After this pre-feed operation, the transport roller 21 is rotated in the reverse direction to transport the roll paper Pr in the reverse direction. At this time, the electromagnetic clutch 66 is turned on, the reverse rotation of the transport roller 21 is transmitted to the rotation load means 75, and the roll paper Pr is rewound simultaneously.

  At this time, the rewinding speed (roll peripheral speed) V ′ of the roll paper Pr is increased so as to be 30% or more faster than the transport speed V of the transport roller 21. The roll paper can be prevented from sagging, and the roll paper can be wound with a predetermined tension. By this tightening operation, when the roll paper is conveyed in the subsequent recording operation or the like, the roll brake T can be applied immediately (immediately) to the roll paper, and the skew correction of the roll paper can be performed efficiently. On the other hand, when the constant roll brake T acts, the roll paper can be conveyed with high accuracy in a stable state. The reverse conveyance is stopped when the roll paper is rewound until it reaches a predetermined position near the downstream side in the conveyance direction of the pinch roller 22. Then, it waits until a recording start signal is input.

  A paper discharge cover 31 for receiving the recording paper Pr and controlling the paper discharge posture is attached to the paper discharge unit 30. A paper discharge port is formed between the paper discharge cover 31 and the top cover 32. The top cover 32 has a closed cavity structure and can be made of a resin blow-molded product. In the present embodiment, a blow-molded product is employed because a lightweight and highly rigid cover can be made and the production cost of the mold is low. In recent years, this blow molding has been widely adopted for exterior parts of large machines.

  FIG. 7 is a schematic perspective view showing the main configuration of the second embodiment of the sheet conveying apparatus according to the present invention. In FIG. 7, the spool 11 for holding the roll paper Pr and the rotational load means 75 attached to the shaft portion 11c of the spool have substantially the same configuration as in the first embodiment. . However, the gear 75e provided in the housing 75c of the rotational load means (torque limiter) 75 of the present embodiment is a helical gear. Therefore, in this embodiment, the gear 75e is driven by a roll driving motor 80, and the driving of the motor 80 is transmitted to the gear 75e via an idler gear 82 composed of a worm and a Hasuba gear as output gears. Is done. As the motor 80 in this case, an inexpensive and small DC motor is employed.

  In the second embodiment of FIG. 7, the roll driving motor 80 is stopped when the roll paper Pr is sent out by the forward rotation of the transport motor 60. Therefore, the worm 81 and the helical gear 82 are fixed (locked), and the rotation load means 75 functions as the roll brake T. On the other hand, in the reverse rotation direction in which the roll paper Pr is rewound, the rotational drive of the motor 80 is transmitted to the rotation load means 75 and functions as a rewind torque generating means. That is, also in this embodiment, the forward rotation direction in which the spool 11 sends the sheet Pr into the gear trains 81, 82, 75 e that transmit the drive to the rotational load means 75 by the worm 81, the idler gear 82, and the helical gear 75 e ( One-way transmission means is configured which is fixed in the (feeding direction) direction and is free in the reverse rotation direction (rewinding direction) in which the spool rewinds the sheet Pr.

That is, as in the case of the first embodiment, a configuration is provided in which unidirectional transmission means 81 and 82 for transmitting the drive in the rewinding direction of the roll paper Pr are provided without transmitting the drive in the direction of feeding the roll paper Pr. Has been.
Further, in the case of the present embodiment, the gear 75e of the rotational load means 75 on the shaft portion 11c of the spool 11 is a helical gear, so that a thrust force (acting force in the axial direction of the spool 11) is generated due to the twist angle, and the backlash is reduced. A shifting function is obtained. For this reason, it is not necessary to provide a backlashing mechanism as in the conventional example.

  In the second embodiment shown in FIG. 7, since it can be driven separately from the conveying means including the conveying roller 21 and the like, the conveying roller 21 is stopped and only the roll paper is rewound (such as winding). Is also possible. This is because, for example, when the roll paper Pr in use is loosened (roll loosened), the roll brake T does not act, which may cause a conveyance failure such as skew feeding or uneven feeding, but as described above. Such a conveyance failure can be prevented by rewinding only the roll paper and performing the tightening. Moreover, in this embodiment, it can comprise with further space saving compared with 1st Embodiment. For example, in recent years, the number of apparatuses that set roll paper as an option is increasing even in office printers, but it can also be used as a configuration of such an optional roll.

  In the embodiment described above, the rotational load means (torque limiter) 75 functions as a constant load (back tension) generating means in the forward rotation (paper feed) direction of the roll-shaped sheet Pr, and in reverse rotation (rewinding). Functions as a rotational torque generating means. It is preferable that the rotation load means 75 can change the set load according to the type of the roll paper Pr by a method such as using a plurality of spools 11 set to a plurality of load values. This is because by setting two or more load torque values according to the difference in characteristics and specifications (thickness, rigidity, width, etc.) of the roll-shaped sheet Pr, a more stable paper feeding and conveying operation can be performed. It is. The gear ratio in the gear train 14 is selected so that the rewind speed of the roll paper is faster than the transport speed of the roll paper even when the winding outer diameter of the roll paper Pr is minimum.

  As shown in the first embodiment, the gear train 14 is configured to transmit the driving of the conveying means (conveying roller) 21 to the rotational load means 75, so that the cost can be reduced by sharing the driving source. . If the gear train 14 has a drive transmission means in which a helical gear 75e on the rotational load means 75 side and a worm 81 on the drive source side are connected, it is possible to further reduce the space of the device configuration and to achieve the helical gear 75e. The spool 11 can be moved away by the thrust force. In this case, the drive source for the rotation load means 75 may be an independent drive source 80 different from the drive source 60 of the transport means 21. In the first embodiment, a one-way such as an electromagnetic clutch 66 that transmits the driving in the direction of rewinding the roll paper Pr but does not transmit the driving in the direction of sending out between the driving source 60 of the conveying means 21 and the gear train 14. By providing the clutch means, it is possible to smoothly and smoothly switch the roll paper feed and rewind.

  That is, a rotary load means 75 as a constant load generating means is provided on a spool 11 that can hold and rotate a roll-shaped sheet (roll paper) Pr, and in the gear train 14 that transmits driving to the rotary load means. Since the one-way gear 14a is provided and the rotation control is performed so that the roll paper is free in the reverse rotation direction (rewinding direction) and stopped (fixed) in the normal rotation direction (feeding direction, paper feeding direction). The means 75 can function as a roll brake during normal rotation (feed) of the roll paper, and can realize a configuration that functions as a rewind torque transmission member during reverse rotation (rewind) of the roll paper. As a result, the following effects can be obtained.

  First, since the sheet is automatically rewound when the sheet is rewound during a paper feeding operation or a discharging operation, a constant roll brake T can be applied for each conveying operation, and the roll diameter and width dimension of the roll paper Regardless of the stiffness or the like, a highly accurate and stable conveying operation can be ensured, and high-quality image recording can be performed. In addition, since the roll brake T is constantly applied for each sheet feeding operation, the skew correction of the roll paper can be performed efficiently, and thereby the margin of the roll paper set of the user (set deviation allowable range). ) Can be expanded, and the operability can be greatly improved.

  In the case of a front operation recording apparatus that feeds and discharges paper from the front as in the illustrated embodiment, the path of the paper feed conveyance is a U-turn. Since there is a return, jamming (paper jam) in the conveyance path can be prevented even when roll paper with low rigidity is used. Since the roll paper can be automatically rewound when the roll paper is replaced, the operability of the recording apparatus is improved. Since the roll brake T = the roll paper rewinding torque Tr, the configuration of the sheet conveying apparatus can be made very simple and inexpensive. Furthermore, since the torque generating means is disposed on the roll paper shaft (spool shaft) that requires the most torque, the drive can be efficiently performed with little loss of drive transmission.

  When the paper width of the roll paper is large or when the roll outer diameter is large, it is necessary to increase both the value of the roll brake T and the value of the roll paper rewinding torque. By increasing the torque setting value of 75, it is possible to cope with it easily and appropriately. According to the configuration in which the helical gears 75e and 82 and the worm 81 are used as a drive transmission mechanism to the rotational load means 75 on the shaft of the spool 11, even if a drive source 80 different from the drive source of the transport means 21 is used, It is possible to perform the same rotation control as described above.

  In the above embodiment, a serial type recording apparatus using a recording head mounted on a carriage has been described as an example. However, the present invention is not limited to a line type recording apparatus that records only by sub-scanning. The present invention can be similarly applied to the recording apparatus of the recording method, and has the same operational effects. Further, in the case of using an inkjet recording head, the present invention is a device that uses one recording head, a device that uses a plurality of recording heads that use different color inks, or a plurality of recording heads that use the same color and different concentrations of ink. The present invention can also be applied in the same way to a device using this, and also to a recording device combining these, and the same effect can be achieved.

FIG. 3 is a schematic perspective view illustrating an embodiment of a recording apparatus including a sheet conveying device according to the present invention. FIG. 2 is a schematic longitudinal sectional view of the recording apparatus in FIG. 1. FIG. 3 is a schematic perspective view illustrating a main part of the first embodiment of the sheet conveying apparatus according to the present invention. It is a longitudinal cross-sectional view which shows the structure of the part of the spool in FIGS. 1-3, and the structure of the rotational load means with which the axial part of this spool was mounted | worn. It is a schematic diagram which shows the principle of the rotational load means of the sheet conveying apparatus by this invention. FIG. 3 is a schematic diagram illustrating the principle of a one-way gear as a one-way transmission unit of a sheet conveying apparatus according to the present invention. It is a typical perspective view which shows the principal part structure of 2nd Embodiment of the sheet conveying apparatus by this invention. It is a typical longitudinal cross-sectional view which illustrates the conventional structure of the recording device which handles a roll-shaped sheet | seat.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Main body of recording apparatus 10 Roll holder part 11 Spool 11c Shaft part 12 (12L, 12R) Flange 14 Gear train 14a Unidirectional transmission means (one-way gear)
15, 16 Roll paper guide 20 Image forming unit 21 Conveying roller 22 Pinch roller 23 Suction platen 23a Suction hole 25 Lower stay 26 Paper feed sensor 30 Paper ejection unit 40 Carriage 41 Recording head 44 Linear sensor 51 Main rail 52 Sub rail 53 Linear scale 60 transport motor 61 transport belt 62 transport pulley 63 transport gear 64 drive belt 65 drive pulley 66 clutch means (electromagnetic clutch)
70 Suction fan 75 Rotary load means (torque limiter)
75e Gear 80 Drive source (motor)
81 Worm (one-way transmission means)
82 idler gear (one-way transmission means)
Pr roll sheet (roll paper)
D Roll outer diameter T Roll brake (tension, back tension)
Tr Load torque by rotating load means X Main scanning direction Y Transport direction (sub scanning direction)

Claims (9)

A spool capable of holding a roll-shaped sheet and rotating in a feeding direction and a rewinding direction; a conveying means for conveying the sheet through an image forming region; and a rotational load means for applying a predetermined rotational load to the spool. In the sheet conveying apparatus provided,
Providing the rotation load means on the shaft portion of the spool;
A sheet conveying apparatus, comprising: a one-way transmission unit that transmits driving in a rewinding direction without transmitting driving in the direction of feeding out the sheet in a gear train that transmits driving to the rotating load unit.   2. The sheet conveying apparatus according to claim 1, wherein the one-way transmission unit includes a one-way gear that is fixed in a direction in which the spool feeds the sheet and is free in a direction in which the spool rewinds the sheet. .   The sheet conveying apparatus according to claim 1 or 2, wherein a set load of the rotation load means can be changed.   The gear ratio of the gear train is selected so that the unwinding speed of the sheet is faster than the conveying speed of the sheet even when the winding outer diameter of the sheet is minimum. 4. The sheet conveying apparatus according to claim 1.   5. The sheet conveying apparatus according to claim 1, wherein the gear train is capable of transmitting the driving of the conveying unit to the rotary load unit.   6. A clutch unit that transmits a drive in a direction of rewinding the sheet but does not transmit a drive in a direction of sending out is provided between a driving source of the conveying unit and the gear train. The sheet conveying apparatus according to claim 1.   2. The sheet conveying apparatus according to claim 1, wherein the gear train includes a drive transmission unit that connects a helical gear on the rotational load unit side and a worm gear on the drive source side.   8. The sheet conveying apparatus according to claim 7, wherein a driving source for the rotational load means is an independent driving source different from a driving source for the conveying means.   A recording apparatus for forming an image on a roll-shaped sheet based on image information, comprising the sheet conveying apparatus according to claim 1.

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