JP2017007812A - Sheet conveying device, printing device and sheet conveying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a decrease in sheet conveying precision of sheet conveyance due to tension variation of a sheet with a simple constitution.SOLUTION: A sheet conveying device comprises: a conveying part which comprises a conveying roller and rotates the conveying roller to convey a sheet; a take-up part which is located downstream of the conveying part in a sheet conveying path, and comprises a rotating body for taking up the conveyed sheet; a detecting part which detects a decrease in tension operating on the sheet in the conveyance path between the conveying part and take-up part; and a control part (S106) which controls a rotating angular speed of the conveying roller and/or rotating body so as to make a peripheral speed of rotation of the conveying roller smaller than a peripheral speed of rotation of the rotating body if the detecting part detects a decrease in tension operating on the sheet (S105) when the take-up part takes up the sheet around the rotating body.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a technique for suppressing a decrease in sheet conveyance accuracy such as meandering caused by fluctuations in sheet tension that may occur when a sheet is wound by a rotating body in sheet conveyance in a printing apparatus or the like.

  For example, there is a case where the tension applied to the sheet fluctuates when the sheet wound around the rotating body is cut by the cutter unit, and the wound sheet may meander due to this. In order to cope with such a decrease in sheet conveyance accuracy, Patent Document 1 describes that the trailing edge of a wound sheet is sucked and held and a predetermined tension is applied to the sheet. Patent Document 1 describes that a member is brought into contact with a conveyed sheet to change the sheet conveyance path so that an appropriate tension is applied to the wound sheet to remove the slack of the sheet. ing. With these configurations, it is possible to always apply an appropriate tension to the conveyed sheet to suppress a decrease in conveyance accuracy such as meandering or slack.

JP 2013-151334 A

  However, the configuration described in Patent Document 1 that suppresses fluctuations in sheet tension that may occur when the sheet is wound requires a member for sucking and holding the above-described sheet and a member for contacting the sheet. It is. For this reason, the structure of the sheet conveying apparatus is complicated by these members, and the size may be increased.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet conveying apparatus, a printing apparatus, and a sheet conveying method that can suppress a decrease in sheet conveying accuracy due to fluctuations in sheet tension with a simple configuration.

  Therefore, according to the present invention, the sheet conveying apparatus includes a conveying unit that includes a conveying roller and rotates the conveying roller to convey the sheet, and a sheet that is located downstream of the conveying unit in the sheet conveying path and is conveyed. Winding means provided with a rotating body for winding, detection means for detecting a decrease in tension acting on the sheet in the conveying path between the conveying means and the winding means, and the winding means is the rotation When the detecting means detects a decrease in tension acting on the sheet when the sheet is wound on the body, the peripheral speed of rotation of the transport roller is made smaller than the peripheral speed of rotation of the rotating body. And control means for controlling the rotational angular velocity of the rotating roller.

  According to the above configuration, in sheet conveyance, it is possible to suppress a decrease in sheet conveyance accuracy due to fluctuations in sheet tension with a simple configuration.

FIG. 2 is a diagram schematically illustrating, in cross section, an internal configuration of a printing apparatus according to an embodiment of the present invention. It is a block diagram which shows the structure of the control part shown by FIG. (A) And (b) is a figure explaining the operation | movement of the single-sided printing mode and double-sided printing mode which concern on one Embodiment of this invention, respectively. It is sectional drawing which mainly shows the structure of the winding rotary body of the inversion part which performs winding operation | movement of a sheet | seat shown by FIG. (A) And (b) is a perspective view which shows the structure of the drive mechanism of the winding rotary body shown by FIG. (A) And (b) is a figure which shows the structure of the principal part of the 2nd gear mechanism shown by FIG. (A)-(c) is a figure explaining the operation | movement at the time of sheet | seat winding-up by a winding rotary body. (A)-(c) is a figure explaining the influence which it has on a sheet conveyance when a sheet | seat is cut | disconnected by a cutter part in sheet winding operation | movement. (A) And (b) is a flow chart which shows conveyance control at the time of sheet winding operation concerning an embodiment of the present invention. (A)-(c) is a figure explaining conveyance control at the time of sheet winding operation concerning an embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  A sheet conveying apparatus according to an embodiment of the present invention relates to a sheet conveying configuration in a printing apparatus. The printing apparatus of the present embodiment is a line printer that uses a sheet wound in a roll shape and supports both single-sided printing and double-sided printing. The present invention is applicable to a printing apparatus such as a printer, a multifunction printer, a copying machine, and a facsimile machine. The printing method may be any method such as an inkjet method, an electrophotographic method, a thermal transfer method, a dot impact method, and a liquid developing method. Further, the present invention is not limited to print processing, and can also be applied to a sheet conveying apparatus that performs various processes (recording, processing, coating, irradiation, reading, inspection, etc.) on a roll sheet.

  FIG. 1 is a diagram schematically showing, in section, the internal configuration of a printing apparatus according to an embodiment of the present invention. The printing apparatus generally includes a sheet supply unit 1, a decurling unit 2, a skew correction unit 3, a printing unit 4, an inspection unit 5, a cutter unit 6, an information recording unit 7, a drying unit 8, a reversing unit 9, and a discharge conveying unit 10. , A sorter unit 11, a discharge unit 12, and a control unit 13. The sheet is conveyed by a conveyance mechanism including a pair of rollers and a belt along a sheet conveyance path indicated by a solid line in the drawing, and each unit performs each process. Note that, at an arbitrary position in the sheet conveyance path, the side close to the sheet supply unit 1 is referred to as “upstream” and the opposite side is referred to as “downstream”.

  The sheet supply unit 1 is a unit for holding and supplying a continuous sheet wound in a roll shape. The sheet supply unit 1 can store two rolls R1 and R2, and can alternatively pull out and supply a sheet. The decurling unit 2 reduces curling (warping) of the sheet supplied from the sheet supply unit 1. In the decurling unit 2, two pinch rollers are used for one driving roller, and the sheet is curved and passed so as to give a curl in the opposite direction of the curl, and a decurling force is applied to reduce the curl. The skew correction unit 3 corrects the skew (inclination with respect to the original traveling direction) of the sheet that has passed through the decurling unit 2. The skew of the sheet is corrected (corrected) by pressing the sheet end on the reference side against the guide member.

  The printing unit 4 prints (records) an image or the like by ejecting ink from the print head 14 onto the conveyed sheet. The print head 14 is a so-called line type print head in which nozzles for ejecting ink are arranged in a range that covers the maximum width of a sheet that is assumed to be used. The print head 14 is provided for each type of ink to be ejected, and these are arranged in parallel along the sheet conveyance direction. This embodiment supports inks of seven colors (types) of C (cyan), M (magenta), Y (yellow), LC (light cyan), LM (light magenta), G (gray), and K (black). 7 print heads are used. In addition to the method using the heating element (heater) of the present embodiment, the inkjet method can employ a method using a piezo element, a method using an electrostatic element, a method using a MEMS element, and the like. . Each color ink is supplied from the ink tank to the print head 14 via an ink tube. The inspection unit 5 optically reads the inspection pattern or image recorded on the sheet by the printing unit 4 using a scanner, and inspects the ejection state of each nozzle, the sheet conveyance state, the image position, etc. in the print head, and the image is correct. Judge whether it is printed. As the scanner, a CCD image sensor or a CMOS image sensor can be used.

  The cutter unit 6 includes a mechanical cutter, and cuts the printed sheet into a length corresponding to the size of the printed image. The cutter unit 6 includes a plurality of conveying rollers for sending the sheet to the next process. A trash can 17 is provided in the vicinity of the cutter unit 6. The trash box 17 accommodates small sheet pieces that are cut off by the cutter unit 6 and discharged as trash. The cutter unit 6 is provided with a sorting mechanism for discharging the cut sheet to the trash box 17 or shifting it to the original conveyance path.

  The information recording unit 7 records print information (unique information) such as a serial number and date corresponding to an image printed in a non-print area where a sheet image separated by cutting is not printed. This recording is performed by printing characters and codes by the thermal transfer method in addition to the ink jet method of the present embodiment. A sensor 23 for detecting the leading edge of the cut sheet is provided on the upstream side of the information recording unit 7 and the downstream side of the cutter unit 6. The sensor 23 detects the edge of the sheet between the cutter unit 6 and the recording position of the information recording unit 7, and the information recording unit 7 controls the timing of information recording based on the detection timing. The drying unit 8 heats the sheet printed by the printing unit 4 to dry and fix the applied ink. Inside the drying unit 8, hot air is applied at least from the lower surface side to the passing sheet to dry the ink application surface.

  The sheet conveyance path from the sheet supply unit 1 to the drying unit 8 is referred to as a first path. The first path has a U-turn shape between the printing unit 4 and the drying unit 8, and the cutter unit 6 is located in the middle of the U-turn shape.

  The connection conveyance path 200 and the reverse conveyance path 201 convey the sheet that has passed through the drying unit 8 to the reversal unit 9. The reversing unit 9 temporarily rolls up and reverses the continuous sheet that has been printed on the front side when performing double-sided printing. The reversing unit 9 supplies the sheet that has passed through the drying unit 8, the connection conveyance path 200, and the reversal conveyance path 201 to the printing unit 4 again from the drying unit 8 to the connection conveyance path 200, the reversal conveyance path 201, and the decurling unit 2. And is provided in the middle of a route (loop path) (referred to as a second route) that reaches the print unit 4. The reversing unit 9 includes a winding rotary body (drum) that rotates to wind up and store the sheet. The continuous sheet that has been printed on the surface and has not been cut is temporarily wound and accommodated in the winding rotary member. When the winding is completed, the winding rotary body rotates reversely, and the wound sheet is supplied to the decurling unit 2 and sent to the printing unit 4. Since this sheet is turned upside down, the printing unit 4 can print on the back side. In the winding operation by the winding rotary body of the reversing unit 9, when the sheet is cut, the control described later with reference to FIGS. 9A and 9B is performed.

  The discharge conveyance unit 10 is a unit for conveying the sheet cut by the cutter unit 6 and dried by the drying unit 8 and delivering the sheet to the sorter unit 11. The discharge conveyance unit 10 is provided in a route (referred to as a third route) different from the second route in which the reversing unit 9 is provided. In order to selectively guide the sheet conveyed on the first path to one of the second path and the third path, the connection conveyance path 200 is provided with a path switching mechanism having a movable flapper. The sorter unit 11 and the discharge unit 12 are provided on the side of the sheet supply unit 1 and at the end of the third path. The sorter unit 11 sorts printed sheets for each group as necessary. The sorted sheets are discharged to the discharge unit 12 including a plurality of trays. As described above, the third path is configured to pass under the sheet supply unit 1 and discharge the sheet to the opposite side of the printing unit 4 and the drying unit 8 with the sheet supply unit 1 interposed therebetween.

  The control unit 13 controls each unit of the entire printing apparatus. The control unit 13 includes a CPU, a storage device, a controller including various control units, an external interface, and an operation unit 15 that is input and output by a user. The operation of the printing apparatus is controlled based on a command from a host device 16 such as a controller or a host computer connected to the controller via an external interface.

  FIG. 2 is a block diagram showing a configuration of the control unit 13 shown in FIG. The controller included in the control unit 13 (range surrounded by a broken line) includes a CPU 201, a ROM 202, a RAM 203, an HDD 204, an image processing unit 207, an engine control unit 208, and an individual unit control unit 209. The CPU 201 (central processing unit) controls the operations of the above-described units of the printing apparatus in an integrated manner. The ROM 202 stores a program to be executed by the CPU 201 and data necessary for various operations of the printing apparatus. The RAM 203 is used as a work area for the CPU 201, used as a temporary storage area for various received data, and stores various setting data. The HDD 204 stores and reads out programs to be executed by the CPU 201, print data, and setting information necessary for various operations of the printing apparatus. The operation unit 15 is an input / output interface with a user, and includes an input unit such as a hard key or a touch panel, and an output unit such as a display or a sound generator for presenting information.

  An image processing unit 207 performs image processing of print data handled by the printing apparatus. The color space (for example, YCbCr) of the input image data is converted into a standard RGB color space (for example, sRGB). Various image processing such as resolution conversion, image analysis, and image correction is performed on the image data as necessary. Print data obtained by these image processes is stored in the RAM 203 or the HDD 204. The engine control unit 208 performs drive control of the print head 14 of the print unit 4 according to print data based on a control command received from the CPU 201 or the like. The engine control unit 208 also controls the transport mechanism of each unit in the printing apparatus. The individual unit control unit 209 includes a sheet supply unit 1, a decurling unit 2, a skew correction unit 3, an inspection unit 5, a cutter unit 6, an information recording unit 7, a drying unit 8, a reversing unit 9, a discharge conveyance unit 10, and a sorter unit. 11, a sub-controller for individually controlling each unit of the discharge unit 12, the connection conveyance path 200, and the reverse conveyance path 201. The individual unit control unit 209 controls the operation of each unit based on a command from the CPU 201. The external interface 205 is an interface (I / F) for connecting the controller to the host device 16 and is a local I / F or a network I / F. The above components are connected by the system bus 210.

  The host device 16 is a device serving as a supply source of image data for causing the printing apparatus to perform printing. The host device 16 may be a general-purpose or dedicated computer, or a dedicated image device such as an image capture having an image reader unit, a digital camera, or a photo storage. When the host device 16 is a computer, an OS, application software for generating image data, and a printing device driver for the printing device are installed in a storage device included in the computer. Note that it is not essential to implement all of the above processing by software, and a part or all of the processing may be realized by hardware.

  Next, the single-sided printing mode and the double-sided printing mode, which are basic operations during printing according to the present embodiment, will be described.

<Single-sided print mode>
FIG. 3A is a diagram for explaining the operation in the single-sided print mode according to the present embodiment. In FIG. 3A, the sheet supplied from the sheet supply unit 1 and processed by the decurling unit 2 and the skew correction unit 3 is printed on the front surface (first surface) in the printing unit 4. An image (unit image) having a predetermined unit length in the conveyance direction is sequentially printed on a long continuous sheet to form a plurality of images side by side. The printed sheet passes through the inspection unit 5 and is cut for each unit image in the cutter unit 6. The cut sheet is recorded with print information on the back side of the sheet by the information recording unit 7 as necessary. Then, the cut sheets are conveyed one by one to the drying unit 8 and dried. Thereafter, the paper is sequentially discharged and stacked on the discharge unit 12 of the sorter unit 11 via the connection transfer path 200, the reverse transfer path 201, and the discharge transfer unit 10. On the other hand, the sheet left on the print unit 4 side by cutting the last unit image is sent back to the sheet supply unit 1, and the sheet is wound on the roll R1 or R2. As will be described later, at the time of feeding back, the decurling force at the decurling unit 2 is adjusted to be small, and the print head 14 is retracted from the sheet. Thus, in single-sided printing, the sheet passes through the first path and the third path and is processed, and does not pass through the second path.

<Double-sided print mode>
FIG. 3B is a diagram for explaining the operation in the duplex printing mode according to the present embodiment. In FIG. 3B, in double-sided printing, the back (second side) print sequence is executed after the front (front) side (first side) print sequence. In the first front surface print sequence, the operation in each unit from the sheet supply unit 1 to the inspection unit 5 is the same as the operation in the single-sided print mode described above. The cutter unit 6 is conveyed to the drying unit 8 as a continuous sheet without performing a cutting operation. After drying the ink on the surface in the drying unit 8, the ink passes through the connection conveyance path 200 and the reverse conveyance path 201, and is not a path on the discharge conveyance unit 10 side (third path) but a path on the reverse unit 9 side (first path). The sheet is guided to the second path). In the second path, the sheet is wound around the winding rotary body of the reversing unit 9 that rotates in the forward direction (counterclockwise direction in the drawing). When all of the scheduled printing on the surface is completed in the printing unit 4, the trailing edge of the print area of the continuous sheet is cut by the cutter unit 6. With reference to the cutting position, the continuous sheet on the downstream side (printed side) in the transport direction is wound up to the rear end (cutting position) of the sheet by the reversing unit 9 through the drying unit 8. On the other hand, at the same time as the winding by the reversing unit 9, the continuous sheet left on the upstream side in the conveyance direction (the printing unit 4 side) with respect to the cutting position does not leave the sheet tip (cutting position) in the decurling unit 2. Then, the sheet is fed back to the sheet supply unit 1, and the sheet is wound on the roll R1 or R2. By this feed back (back feed), collision with a sheet supplied again in the following back surface printing sequence is avoided. As will be described later, at the time of feeding back, the decurling force at the decurling unit 2 is adjusted to be small, and the print head 14 is retracted from the sheet.

  After the above-described front surface print sequence, the back surface print sequence is switched. The winding rotary body of the reversing unit 9 rotates in the opposite direction (clockwise direction in the drawing) to that during winding. The end of the wound sheet (the trailing edge of the sheet at the time of winding becomes the leading edge of the sheet at the time of feeding) is fed into the decurling unit 2 along the path of the broken line in the figure. In the decurling unit 2, the curl imparted by the winding rotary member is corrected. That is, the decurling unit 2 is provided between the sheet supply unit 1 and the printing unit 4 in the first path and between the reversing unit 9 and the printing unit 4 in the second path, and functions as a decal in any path. It is a common unit. The sheet whose front and back sides are reversed is sent to the printing unit 4 through the skew correction unit 3 and printed on the back side of the sheet. The printed sheet passes through the inspection unit 5 and is cut into predetermined unit lengths set in advance in the cutter unit 6. Since the cut sheet is printed on both sides, recording by the information recording unit 7 is not performed. Cut sheets are conveyed one by one to the drying unit 8, and are sequentially discharged and stacked on the discharge unit 12 of the sorter unit 11 via the connection conveyance path 200, the reverse conveyance path 201, and the discharge conveyance unit 10. As described above, in duplex printing, a sheet passes through the first path, the second path, the first path, and the third path in this order.

  FIG. 4 is a cross-sectional view mainly showing a configuration of the winding rotary body of the reversing unit 9 that performs the winding operation of the sheet according to the present embodiment. The winding rotary body 104 has a hollow cylindrical shape (drum shape) at least partially inside, and the cylindrical surface is a sheet winding surface. The sheet S is introduced into and discharged from the winding rotary member 104 by a pair of conveyance rollers 151 including the conveyance roller 102 and the pinch roller 103. An edge sensor 101 is provided in front of the conveyance roller 102 in the sheet S introduction direction. The edge sensor 101 detects the leading edge of the sheet introduced into the reversing unit 9.

  A slit-like opening as the sheet insertion portion 160 is provided on the cylindrical surface of the winding rotary body 104. A holding roller pair 150 including a holding roller 108 and a pinch roller 107 that can nip and rotate the leading end of the sheet is provided near the inner side of the sheet winding surface of the insertion portion 160. The pinch roller 107 is energized with a predetermined force with respect to the holding roller 108 and is driven to rotate. The leading end of the sheet S introduced into the reversing unit 9 is inserted into the sheet insertion unit 160. The leading end of the inserted sheet S is nipped and held by the holding roller pair 150. Further, when the holding roller 108 rotates, the inserted sheet can be drawn into the internal space of the winding rotary body 104. That is, the holding roller pair 150 has a function as a clamp for holding the sheet and a function as a conveying unit for conveying the sheet.

  The flag 105 is provided at one end of the winding rotary body 104 having a cylindrical shape (see FIG. 5A), and is used as a reference for detecting the origin (initial position) of the rotational position of the winding rotary body 104. Become. The rotation sensor 106 is a sensor that detects the rotation position of the winding rotary body 104. FIG. 4 shows a state in which the position of the winding rotary member 104 is at the initial position, and the sheet insertion portion 160 faces the sheet introduction path.

  Note that both the holding roller 108 and the pinch roller 107 constituting the holding roller pair 150 may have a driving force. Further, both the holding roller 108 and the pinch roller 107 are not limited to a roller shape, and one or both of them may be a rotating body such as an endless belt rotating body. Further, one of the rotating bodies may have a driving force and the other may be a simple sliding surface. In other words, the holding roller pair 150 is configured by the holding roller 108 and the pinch roller 107 is merely an example. In short, if the sheet has a function of niping and rotating the sheet leading edge to convey the sheet, the form is It doesn't matter. In the present specification, these various forms are collectively referred to as a “rotating holder”.

  FIGS. 5A and 5B are perspective views showing the configuration of the drive mechanism of the winding rotary body 104 shown in FIG. In FIG. 5A, a first drive mechanism is provided on the front side of the winding rotary body 104 in the drawing, and a second drive mechanism is provided on the back side. FIG. 5B is a view as seen from the opposite side to FIG. 5A. In FIG. 5B, the second drive mechanism is shown on the front side of the winding rotary body 104 in the drawing, and the second drive mechanism is shown on the back side. One drive mechanism is provided. FIGS. 6A and 6B are diagrams showing the configuration of the main part of the second gear mechanism shown in FIG. Among these, Fig.6 (a) has shown the hollow internal structure which removed the winding surface of the winding rotary body 104, and FIG.6 (b) has shown the gear coupling | bonding.

  The first drive mechanism includes a first drive motor 109 and a first gear train that transmits the rotation of the first drive motor 109 to the rotation shaft of the winding rotary body 104. The first gear train includes a motor gear 109a, a gear 110, a clutch unit 111, a gear 112, a gear 113, and a drum gear 114. The clutch unit 111 includes an input gear 111a, an output gear 111b, and a clutch portion 111c, and can manage drive transmission and tension during sheet winding. The transmission of the drive by the clutch unit 111 does not transmit the input torque 100%, but transmits the drive while the output gear 111b slips with respect to the input gear 111a so that a constant value of torque is output. Is done. The rotation of the first drive motor 109 is decelerated at a predetermined gear ratio by the first gear train and transmitted to the drum gear 114. The drum gear 114 is fixed to a rotation shaft 104a that is the center of rotation of the winding rotary body 104, and the drum gear 114 and the winding rotary body 104 rotate together. At the time of winding the sheet, the rotating body 104 rotates so that the peripheral speed (tangential speed) due to the rotation of the winding rotating body 104 is larger than the conveying speed of the sheet introduced by the pair of conveying rollers arranged on the upstream side of the rotating body 104. The rotational angular speed 104 is controlled. This speed difference is absorbed by the output gear 111b slipping with respect to the input gear 111a of the clutch unit 111. As a result, the peripheral speed of the outer periphery of the winding rotary body 104 is higher than that of the rotary body 104. The speed is the same as that of the conveying roller pair. Due to the slip, a braking force acts on the winding rotary member 104, and a predetermined tension is applied to the seat. The winding rotary body 104 rotates while winding the sheet while being pulled from the sheet with a predetermined tension.

  On the other hand, the second drive mechanism has a second drive motor 115 and a second gear train that transmits the rotation of the second drive motor 115 to the rotation shaft of the holding roller 108. The second gear train includes a motor gear 115a, a clutch unit 117, a gear 118, a transmission gear 119, a gear 120, and a roller gear 121. The clutch unit 117 includes an input gear 117a, an output gear 117b, and a clutch portion 117c, and can switch between transmission and disconnection of rotational force. The rotation of the second drive motor 115 is decelerated at a predetermined gear ratio by the second gear train and transmitted to the roller gear 121. The roller gear 121 is fixed to a rotating shaft that is the center of rotation of the holding roller 108, and the roller gear 121 and the holding roller 108 rotate together. The transmission gear 119 has an integrated input gear 119a and output gear 119b. Both the input gear 119a and the output gear 119b have the same rotation center as the rotation shaft 104a of the winding rotary body 104, and rotate idle with respect to the rotation shaft 104a. A lock gear 125 is fixed to the end of the rotating shaft 104a. The lock gear 125 and the transmission gear 119 are connected by a clutch unit 124 that can switch between transmission and disconnection of force. The clutch unit 124 includes an input gear 124a that meshes with the lock gear 125 and an output gear 124b that meshes with the input gear 119a. That is, two of the gear 118 and the output gear 124b mesh with the input gear 119a.

  Note that both ends of the rotating shaft of the pinch roller 107 are rotatably supported by a pinch roller bearing 123. The pinch roller bearing 123 is biased downward by a pinch roller spring 122, whereby the pinch roller 107 is biased against the holding roller 108.

  In the above configuration, when the holding roller 108 is rotated by the second drive motor 115, the clutch unit 117 is connected and the clutch unit 124 is disconnected. When the second drive motor 115 is driven in this state, the rotation of the second drive motor 115 is transmitted to the roller gear 121 via the gear 120, and the holding roller 108 rotates (autorotates). In this example, the holding roller 108 which is one roller constituting the holding roller pair 150 is driven by the second drive motor 115, but the side of the pinch roller 107 may be driven. Alternatively, both the holding roller 108 and the pinch roller 107 may be driven.

  When the sheet is wound around the winding rotary member 104, the holding roller 108 is not rotated (the locked state with respect to the winding rotary member 104) while the leading end of the sheet is nipped by the holding roller pair 150. In this case, the clutch unit 117 is disconnected and the rotational force from the second motor is disconnected, and the clutch unit 124 is connected. As a result, the transmission gear 119 rotates with the lock gear 125 at a constant speed, that is, the transmission gear 119 does not rotate relative to the rotating shaft 104a (a state that can be regarded as a substantially integrated object). Along with this, the gear 120 and the holding roller 108 are also not rotated relative to the winding rotary body 104 (a state in which the rotation is not performed). When the first drive motor 109 is driven in this state, the rotation of the first drive motor 109 is transmitted to the drum gear 114, and the take-up rotating body 104 rotates to take up the sheet. At this time, the holding roller 108 is stationary without rotating.

  FIGS. 7A to 7C are diagrams illustrating an operation at the time of winding a sheet by the winding rotary body described above.

  At the initial position shown in FIG. 7A, the sheet insertion portion 160 of the winding rotator 104 faces the sheet introduction path, whereby the sheet S introduced into the winding rotator 104 is transferred to the sheet insertion portion 160. Go inserted. Specifically, the sheet S is conveyed in the introduction direction, and this conveyance indicates that “when the edge sensor 101 detects that the leading edge of the sheet S passes, the position where the leading edge of the sheet S passes the nip portion of the holding roller pair 150. Next, as shown in Fig. 7B, the holding roller pair 150 is made stationary with respect to the winding rotary body 104 after passing through the nip portion, and the center axis of the rotary body 104 is set as the center. The sheet is driven so as to rotate in the sheet winding direction, and winding of the sheet S by the winding rotating body 104 is started, and as shown in Fig. 7C, the length of the wound sheet increases. Further, the winding thickness of the sheet wound around the winding rotary body 104 also increases.

  When winding the sheet by the rotating body 104 as described above, a predetermined tension is required so as not to cause sheet deflection on the rotating body 104 in order to prevent a winding failure. As an example of the method, the sheet winding speed is set to a certain level or more in accordance with the sheet speed introduced into the rotating body 104. That is, at the time of sheet winding, the first drive motor is controlled so that the peripheral speed due to rotation of the sheet winding is larger than the conveying speed of the sheet introduced by the pair of conveying rollers upstream of the rotating body 104. Set the rotation angular velocity. In the clutch unit 111, the output gear 111b slips with respect to the input gear 111a. Therefore, even if the sheet winding thickness increases, the peripheral speed due to the rotation of the winding rotary member 104 follows the upstream conveying roller pair. Will keep a constant speed. As another method, in order to prevent the peripheral speed of the outer periphery of the sheet (the sheet winding speed in the tangential direction) from changing even if the winding thickness of the wound sheet increases, the rotational angular speed of the first drive motor is You may control so that it may reduce little by little with the increase in winding thickness. Information regarding the winding thickness of the sheet can be obtained from the sheet length of the wound sheet.

  FIGS. 8A to 8C are views for explaining the influence on sheet conveyance when the sheet is cut by the cutter unit in the sheet winding operation described above. These figures show the state of the conveyed sheet from the reversing part to the cutter part at the time of cutting (cutting) the sheet. Unlike FIG. 1, the conveying path is shown as a straight line for easy understanding. . As shown in these drawings, a loop-shaped slack portion 203 is formed between the inspection unit 5 and the cutter unit 6 due to the difference in peripheral speed between the pair of conveying rollers 204, so that the downstream side from the cutter unit 6. Disturbance factors with respect to the sheet tension, such as speed fluctuations, are not transmitted upstream from the cutter unit 6.

  FIG. 8A shows a state in which the sheet is wound around the rotating body 104, and the sheet is transported on the upstream side of the rotating body 104, that is, the connection conveying path 200, the reverse conveying path 201, and the drying. Nipping is performed by a pair of conveying rollers of the section 8, the information recording section 7, and the cutting section 6. The sheet conveyance speed by the rotating body 104 and the conveyance roller pair in each conveyance unit is set in advance according to the roll paper type of the sheet supply unit 1, the paper type detected by the sensor that detects the paper width, and the paper width. Here, the set value for a certain paper type and paper width is P1 (m / sec) as the peripheral speed due to the rotation of the rotating body, and P2 (m / sec) as the peripheral speed due to the rotation of the conveying roller pair upstream from the rotating body. sec). Further, in the present embodiment, the drying unit 8 is configured to abut on the belt to which heat has been applied with a plurality of conveyance rollers in the sheet conveyance direction and the sheet width direction in order to sufficiently heat the sheet. is there. For this reason, the conveyance force is larger than that of other conveyance units, and this conveyance force leads the conveyance of the sheet in the entire conveyance path shown in FIG. In this example, the conveying force of the drying unit 8 is greater than the other conveying forces, thereby leading the sheet conveyance, but it goes without saying that other conveying paths may be used. If the conveying force of the rotating body is F1 (N), and the conveying force on the upstream side is the conveying force of the drying unit 8 that mainly leads the conveying, and that is F2 (N), P1> P2, F1 < The relationship is F2. As a result, the rotating body 104 is configured to wind while being slid by the action of the clutch, and a predetermined tension f1 (N) acts on the sheet wound around the rotating body 104 mainly by the conveying force of the drying unit 8, Winding is performed without sagging of the sheet.

  FIG. 8B shows a state of the sheet from the reversing unit 9 to the cutter unit 6 immediately after resuming the winding after the sheet to be wound is cut by the cutter unit 6. FIG. 8C shows the state of the sheet when the trailing edge of the sheet passes through the drying unit 8 after the sheet is cut. That is, when printing on the sheet is completed, the sheet conveyance in all the conveyance paths is temporarily stopped, and the sheet is cut by the cutter unit 6. Thereafter, the winding of the sheet is resumed.

  By the way, in the sheet conveyance at the time of winding the sheet as described above, if the sheet on which the tension is applied is cut, a variation in tension occurs due to the release of the sheet tension. Further, since each of the rotating body 104 and the pair of transport rollers of each unit is driven by a separate drive mechanism, it may be difficult to make the conditions during deceleration and acceleration during transport the same. As a result, when the sheet winding is resumed after the sheet is cut, sheet slacks 205a, 205b, and 205c occur as shown in FIG. 8B. If the difference between the peripheral speed due to the rotation of the rotating body and the peripheral speed due to the rotation of the upstream conveying roller pair is the same as before the cut, this slackness takes a relatively long time until the slack is eliminated by winding. May be required.

  Further, as shown in FIG. 8C, when the trailing end of the cut sheet starts to pass through the drying unit 8, the tension in the direction opposite to the winding direction of the rotating body 104 acting on the sheet gradually increases. When the trailing edge of the sheet passes through the drying unit 8, the conveying force on the upstream side becomes F3 (N) (<F1). As a result, the tension cannot act on the sheet under the same conditions as before the sheet is cut, and winding of the rotating body 104 may occur. Further, when the back side printing is performed thereafter, the conveyance roller pair 151 and the rotating body 104 are rotationally driven in the direction opposite to the introduction direction (sheet feeding direction). Since it is the leading edge in backside printing, the sheet may meander and cause paper jams.

Next, an embodiment of the present invention that suppresses a decrease in sheet conveyance accuracy, such as loosening and meandering during sheet winding as described above, will be described below.
(First embodiment)
In the first embodiment of the present invention, when the sheet is cut at the cutting unit 6, the conveyance control is performed so as to increase the speed difference between the rotating body 104 and the upstream conveyance roller pair. Thus, the sheet deflection of the sheet at the time of sheet cutting is eliminated, and the decrease in sheet tension when the sheet trailing edge passes through the drying unit 8 is compensated. As a result, a conveyance load is generated on the sheet by the conveyance roller pair of each unit arranged on the upstream side of the rotating body 104, and tension can be applied to the sheet that is wound and conveyed.

  FIGS. 9A, 10 </ b> A, and 10 </ b> B are diagrams illustrating conveyance control during the sheet winding operation according to the first embodiment of the present invention.

  As shown in FIG. 9A, when sheet winding is started, first, the sheet type (type) and sheet width (width) of the sheet are acquired by the sensor of the sheet feeding unit (S101). Next, based on the paper type and the paper width, the peripheral speed due to the rotation of the winding rotary body 104 described above with reference to FIG. 8A is set to P1, and the unit 6 in the conveyance path on the upstream side of the rotary body, The peripheral speeds due to the rotation of the respective transport roller pairs of 7, 8, 200, and 201 are set to P2, respectively (S102). Then, the sheet is printed on the sheet while the sheet is wound and conveyed by the rotating body 104 in this speed relationship. The sheet conveyance related to the predetermined peripheral speed is performed until the end of printing corresponding to the image data to be printed is detected (S103). When the end of printing is detected, the sheet conveyance is stopped (S104), and the trailing end side of the sheet on which printing has been performed in the cutting unit 6 is cut (S105).

  When the sheet is cut by the cutter unit 6, the control unit 13 detects this as a decrease in the tension acting on the sheet, and the peripheral speed due to the rotation of the winding rotary member 104 is set to P1 as described above. Is set to P3 (m / sec), which is smaller than P2 (S106), by rotating the conveyance roller pairs of the units 7, 8, 200, and 201 in the upstream conveyance path. Then, the winding and conveyance of the sheet by the rotating body 104 are resumed due to the relationship of the peripheral speed, and the sheet conveyance is stopped when the edge sensor 101 in the introduction portion of the rotating body 104 detects the sheet trailing edge (S107).

  As described above, after the sheet is cut, the peripheral speed of rotation of the conveying roller pair on the upstream side of the take-up rotating body is decreased, and the difference in peripheral speed between the rotating body 104 and the conveying roller pair is increased. Control. Thereby, when the relationship of F1 <F2 is maintained with respect to the conveyance force before the sheet passes through the drying unit 8, the sheet is loose between the rotating body 104 and the drying unit 8 (FIG. 8B). Can be shortened.

  In addition, when the rear end of the sheet passes the drying unit 8 (FIG. 8C), the relationship of F1 <F2 cannot be maintained with respect to the conveyance force, as shown in FIG. The peripheral speed due to the rotation of each conveyance roller pair in the path 201 is slowed down to P3 (m / sec). Accordingly, the tensile force Fa on the upstream side in the sheet conveying direction can be increased in the connected conveying path 200 and the reverse conveying path 201 as compared with the case of the peripheral speed P2 (m / sec), and tension can be applied to the sheet. it can. Thereafter, as shown in FIG. 10B, when the trailing edge of the sheet passes through the coupled conveying path 200, the upstream conveying force decreases to F4 (N), but the tension acting on the sheet at the peripheral speed P3. Thus, the tensile force Fc can act on the sheet on the upstream side of the winding rotary body. As a result, the sheet winding meander on the rotating body can be suppressed by maintaining the tension on the sheet until it is wound around the rotating body 104.

(Second Embodiment)
According to the second embodiment of the present invention, on the upstream side of the winding rotary body 104, depending on the position of the sheet in the reverse conveyance path 201 which is the unit closest to the rotary body 104 and the next connected conveyance path 200, The speed of each conveyance roller pair is changed.

  FIGS. 9B, 10 </ b> B, and 10 </ b> C are diagrams illustrating the conveyance control during the sheet winding operation according to the second embodiment of the present invention. In FIG. 9B, the processing of steps S201 to S205 is the same as the processing of steps S101 to S105 shown in FIG. In FIG. 9B, in step S206, after the sheet is cut, the peripheral speed of rotation of the winding rotary member 104 is set to the same P1 as above, and the units 7 and 8 in the conveyance path on the upstream side of the rotary member. , 200, and 201 are set to P4 (m / sec) smaller than P2 and larger than P3, respectively. Then, the winding and conveyance of the sheet by the rotator 104 are resumed based on the peripheral speed, and the sheet is wound and conveyed until the sheet detection sensor 206 in the connection conveyance path 200 detects the trailing edge of the sheet (S207). . When the sheet detection sensor 206 detects the trailing edge of the sheet, in step S208, the winding rotary member is obtained after a predetermined time after the sheet trailing edge passes the roller pair 200b of the connection conveyance path 200, which is obtained from the sheet conveyance speed at that time. The peripheral speed of rotation 104 is set to P1 as described above, and the peripheral speed of rotation of the transport roller pair of the unit 201 in the transport path on the upstream side of the rotating body is set to P3. Then, the sheet is wound and conveyed by the rotating body 104 in relation to the peripheral speed, and the sheet conveyance is stopped when the edge sensor 101 in the introduction portion of the rotating body 104 detects the trailing edge of the sheet (S209).

  As described above, after the sheet is cut, the speed of each pair of conveying rollers is determined according to the position of the sheet in the reverse conveying path 201 which is the unit closest to the rotating body 104 and the next connected conveying path 200. change. Thereby, when the relationship of F1 <F2 is maintained about conveyance force, the time which eliminates the slack of the sheet | seat between the rotary body 104 and the drying part 8 can be shortened similarly to 1st Embodiment. .

  Also, as shown in FIG. 10C, when the rear end of the sheet passes through the drying unit 8 with respect to the conveying force, F1 <F2 cannot be maintained, the conveying rollers in the connected conveying path 200 and the reverse conveying path 201. When nipping in pairs, the circumferential speed of rotation of the conveyance rollers is set to P4, a conveyance load is generated on the take-up rotating body 104, and a tensile force Fb on the upstream side in the conveyance direction is applied to the sheet.

  Then, as shown in FIG. 10B, when the sheet trailing sensor passes through the coupled conveying roller pair 200b, which is the timing at which the sheet detection sensor 206 detects the trailing edge of the sheet, the peripheral speed of rotation of the conveying roller pair is set. By further lowering as P3 (m / sec), the conveyance load can be further increased. As a result, a force Fc that pulls the sheet to the upstream side in the conveyance direction acts, and meandering accompanying the sheet winding can be suppressed until the sheet is wound around the rotating body portion 104.

  In the above example, the position where the peripheral speed of rotation is lowered step by step is one location of the sheet detection sensor 206, but a plurality of positions can be arranged near other conveyance roller pairs and can be controlled stepwise. . Further, although the sensor is used as the sheet trailing edge detection, as another configuration, the load torque is detected from the current waveform of the driving motor of each conveyance roller pair, and the sheet trailing edge passes when the current value falls below a predetermined value. Can be detected. Also in this case, it is possible to control in a stepwise manner at a plurality of locations such as the connected transport roller pair 200a and the reverse transport roller pair 201a instead of one location of the connected transport roller pair 200b.

  According to the above-described embodiment, the speed difference between the rotating unit and the conveying unit is increased uniformly or stepwise from before detection at the timing of changing the sheet tension, and the sheet is provided with a configuration for applying tension to the rotating body 104. The winding meandering can be reduced, and the back meandering and conveying meandering can be reduced.

  In addition, according to the above embodiment, although the double-sided printing machine was demonstrated, it unwinds on the sheet wound by roll shape, winds a roll etc. again by winding a rotary body etc. after image formation on the surface in a recording part. Of course, the present invention can also be applied to an apparatus.

  Further, in the above-described embodiment, in the control of the peripheral speed of the rotation of the rotating body and the transport roller pair at the time of cutting the sheet, the peripheral speed of only the transport roller pair is controlled to generate a speed difference. I can't. For example, the peripheral speed of rotation of the rotating body may be increased to cause a speed difference, or both peripheral speeds may be changed, resulting in the peripheral speed of rotation of the rotating body being greater than the peripheral speed of the conveying roller pair. It may be made larger.

DESCRIPTION OF SYMBOLS 4 Print part 6 Cutter part 8 Drying part 9 Sheet winding part 13 Control part 14 Print head 15 Controller 104 Winding rotary body 150 Holding roller pair 151 Conveyance roller pair 200 Connection conveyance path 201 Reverse conveyance path 202 Cutter

Claims (9)

A conveyance unit that includes a conveyance roller, and conveys the sheet by rotating the conveyance roller;
A winding unit that is positioned downstream of the conveying unit in the sheet conveyance path and includes a rotating body for winding the conveyed sheet;
Detecting means for detecting a decrease in tension acting on the sheet in the conveying path between the conveying means and the winding means;
When the detecting means detects a decrease in the tension acting on the sheet when the winding means is winding the sheet around the rotating body, the peripheral speed of rotation of the transport roller is set to the rotational speed of the rotating body. Control means for controlling the rotational angular velocity of the conveying roller and / or the rotating body so as to be smaller than the velocity;
A sheet conveying apparatus comprising:   A cutting means for cutting the sheet conveyed by the conveying means located upstream of the conveying means in the sheet conveying path, wherein the detecting means is configured such that the conveyed sheet is cut by the cutting means. The sheet conveyance device according to claim 1, wherein a decrease in the tension is detected by the method.   3. The sheet conveying apparatus according to claim 1, wherein the winding unit feeds the sheet by rotating the rotating body in a direction opposite to that at the time of winding.   The transport unit includes a plurality of transport rollers from upstream to downstream in the transport path, and the control unit calculates a difference between a peripheral speed of rotation of the rotating body and a peripheral speed of rotation of the transport roller. 4. The sheet conveying apparatus according to claim 1, wherein the number is increased stepwise according to the position of the sheet on the conveying roller. 5. A conveyance unit that includes a conveyance roller, and conveys the sheet by rotating the conveyance roller;
Printing means for printing an image on a sheet conveyed by the conveying means;
A winding unit that is positioned downstream of the conveyance unit in a conveyance path of the sheet and includes a rotating body for winding the sheet conveyed by the conveyance unit and printed by the printing unit;
Detecting means for detecting a decrease in tension acting on the sheet in the conveying path between the conveying means and the winding means;
When the detecting means detects a decrease in the tension acting on the sheet when the winding means is winding the sheet around the rotating body, the peripheral speed of rotation of the transport roller is set to the rotational speed of the rotating body. Control means for controlling the rotational angular velocity of the conveying roller and / or the rotating body so as to be smaller than the velocity;
A printing apparatus characterized by comprising:   A cutting means for cutting the sheet conveyed by the conveying means located upstream of the conveying means in the sheet conveying path, wherein the detecting means is configured such that the conveyed sheet is cut by the cutting means. The printing apparatus according to claim 5, wherein a decrease in the tension is detected by the method.   The printing apparatus according to claim 5, wherein the winding unit feeds the sheet by rotating the rotating body in a direction opposite to that at the time of winding.   The transport unit includes a plurality of transport rollers from upstream to downstream in the transport path, and the control unit calculates a difference between a peripheral speed of rotation of the rotating body and a peripheral speed of rotation of the transport roller. The printing apparatus according to claim 5, wherein the number is increased in a stepwise manner according to the position of the sheet on the conveying roller. A conveyance unit that includes a conveyance roller, and conveys the sheet by rotating the conveyance roller;
A winding unit that is positioned downstream of the conveying unit in the sheet conveyance path and includes a rotating body for winding the conveyed sheet;
A sheet conveying method in a sheet conveying apparatus comprising:
When the winding unit is winding the sheet on the rotating body, the rotation of the conveyance roller is detected when a decrease in tension acting on the sheet in the conveyance path between the conveyance unit and the winding unit is detected. The sheet conveying method is characterized in that the rotational angular velocity of the conveying roller and / or the rotating body is controlled so that the circumferential speed of the rotating body is smaller than the circumferential speed of the rotating body.