JP5631051B2 - Printing device - Google Patents

Description

  The present invention relates to a printing apparatus that performs printing by conveying a sheet using a conveyance roller.

  Patent Document 1 discloses a printing apparatus provided with a pair of left and right regulation guides for preventing meandering in a paper path path of roll paper. By moving the left and right guides to the position pushed in from the roll paper width to correct the posture of the roll paper, and then moving the roll paper width guide position, meandering of the roll paper can be prevented.

JP 2007-225947 A

  In the apparatus of Patent Document 1, a conveyance roller is provided upstream and downstream of the paper width guide, and roll paper is nipped and conveyed. When the meandering correction is performed, the pressure contact of the transport roller is released, and the operation of pushing the end of the roll paper further than the paper width is performed by the guide means. Further, the position of the guide means is moved in accordance with the width dimension of the roll paper input to the apparatus in advance.

However, in order to cope with a wider range of user needs than before, various media can be conveyed with higher accuracy than before, and good printing results can be obtained.
(1) When meandering occurs during printing, the roll paper transport accuracy deteriorates if the pressure roller is released when the meandering correction is performed by the guide means. Further, if the pressure contact force of the transport roller is weakened to perform meandering correction without releasing the pressure contact, this also deteriorates the roll paper transport accuracy.
Therefore, it is difficult to ensure both good transport accuracy during printing and meander correction performance.
(2) If the operation of pushing the guide means further than the paper width is performed, the roll paper may buckle depending on the rigidity of the roll paper to be used, and damage to the roll paper may remain.
(3) The position of the guide means is adjusted with respect to the roll paper width size inputted in advance, but the guide means and the end of the roll paper depending on the error of the actual roll paper width and input value, part accuracy of the guide means, positioning accuracy, etc. There is a high possibility that a meandering occurs due to a gap between the two. Conversely, when the guide position is swung in the direction of pushing the roll paper, the same phenomenon as in (2) may occur.

  The present invention has been made based on recognition of the above problems. One of the objects of the present invention is to provide a recording apparatus capable of achieving both high levels of roll paper conveyance accuracy and meandering correction accuracy, and as a result, capable of printing high-quality printing results. Another object of the present invention is to provide a printing apparatus capable of performing meandering correction corresponding to various types of roll paper without damaging the roll paper.

  In order to achieve the above object, the present invention provides a print head for printing on a sheet, a conveyance roller arranged on the upstream side of the print head in the sheet conveyance direction, and upstream of the conveyance roller in the sheet conveyance direction. A loop region disposed on the side for forming a loop on the sheet, and a contact surface disposed between the transport roller and the loop region and contacting a side edge of the sheet in a direction intersecting the sheet transport direction In the printing apparatus including the movable guide member, the guide member includes a sensor for detecting a side edge of the sheet, and the contact surface and the sheet are detected before the side edge of the sheet is detected by the sensor. The side edge of the sheet is disposed at a position separated from the side edge, and when the side edge of the sheet is detected by the sensor, the contact surface and the side edge of the sheet are in contact with each other. Characterized in that it is moved to.

  According to the present invention, it is possible to provide a printing apparatus that can achieve both high levels of roll paper conveyance accuracy and meandering correction accuracy and, as a result, can print high-quality printing results. In addition, there is provided a printing apparatus capable of performing meandering correction corresponding to various types of roll paper without damaging the roll paper.

FIG. 2 is a schematic diagram illustrating an internal configuration of a printing apparatus. The block diagram of a control part. The figure for demonstrating the operation | movement in single-sided printing mode. The figure for demonstrating the operation | movement in duplex printing mode. FIG. 3 is a detailed configuration cross-sectional view and a configuration top view of a print unit. FIG. 3 is a detailed explanatory view of a meandering correction guide unit. Explanatory drawing of the control part of a conveyance part and a meandering correction | amendment part. The flowchart which shows a meandering correction | amendment operation | movement. 6 is a flowchart illustrating an operation during reverse sheet conveyance.

  Hereinafter, an embodiment of a printing apparatus using an inkjet method will be described. The printing apparatus of this example is a high-speed line printer that uses a continuous sheet wound in a roll shape and supports both single-sided printing and double-sided printing. For example, it is suitable for the field of printing a large number of sheets in a print laboratory or the like. The present invention can be applied to a printing apparatus such as a printer, a multifunction printer, a copying machine, and a facsimile machine. In addition, the present invention is not limited to a printing apparatus, but is an industrial device (manufacturing apparatus for various devices, inspection apparatus, etc.) used in a factory or the like where a user designates an apparatus operating time and requires a long time for initialization at startup The present invention can be widely applied to various devices such as.

  FIG. 1 is a schematic cross-sectional view showing the internal configuration of the printing apparatus. The printing apparatus according to the present embodiment can perform double-sided printing on the first surface of the sheet and the second surface on the back surface side of the first surface using the sheet wound in a roll shape. Inside the printing apparatus, there are roughly 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 unit. Each unit includes a transport unit 10, a sorter unit 11, a discharge unit 12, a humidification unit 20, and a control unit 13. A sheet is conveyed by a conveyance mechanism including a roller pair and a belt along a sheet conveyance path indicated by a solid line in the drawing, and is processed in each unit.

  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 R <b> 1 and R <b> 2, and is configured to selectively pull out and supply a sheet. The number of rolls that can be stored is not limited to two, and one or three or more rolls may be stored.

  The decurling unit 2 is a unit that 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, thereby applying a decurling force to reduce the curl.

  The skew correction unit 3 is a unit that corrects skew (inclination with respect to the original traveling direction) of the sheet that has passed through the decurling unit 2. The sheet skew is corrected by pressing the sheet end on the reference side against the guide member.

  The printing unit 4 is a unit that forms an image by performing a printing process on the conveyed sheet from above with the print head 14. That is, the print unit 4 is a processing unit that performs a predetermined process on the sheet. The printing unit 4 also includes a plurality of conveyance rollers that convey the sheet. The print head 14 has a line type print head in which an inkjet nozzle row is formed in a range that covers the maximum width of a sheet that is supposed to be used. The print head 14 has a plurality of print heads arranged in parallel along the transport direction. In this example, there are seven print heads corresponding to seven colors of C (cyan), M (magenta), Y (yellow), LC (light cyan), LM (light magenta), G (gray), and K (black). . The number of colors and the number of print heads are not limited to seven. As the inkjet method, a method using a heating element, a method using a piezo element, a method using an electrostatic element, a method using a MEMS element, or the like can be adopted. 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 printed on the sheet by the printing unit 4 using a scanner, and inspects the nozzle state of the print head, the sheet conveyance state, the image position, etc., and the image is printed correctly. This is a unit for determining whether or not. The scanner has a CCD image sensor and a CMOS image sensor.

  The cutter unit 6 is a unit including a mechanical cutter that cuts a printed sheet into a predetermined length. The cutter unit 6 also includes a plurality of conveyance rollers for sending out the sheet to the next process.

  The information recording unit 7 is a unit that records print information (unique information) such as a print serial number and date in a non-print area of the cut sheet. Recording is performed by printing characters and codes using an inkjet method, a thermal transfer method, or the like. 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. That is, the sensor 23 detects the edge of the sheet between the cutter unit 6 and the recording position by the information recording unit 7, and the information recording unit 7 controls the timing of information recording based on the detection timing of the sensor 23.

  The drying unit 8 is a unit for heating the sheet printed by the printing unit 4 and drying the applied ink in a short time. 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 drying method is not limited to the method of applying hot air, and may be a method of irradiating the sheet surface with electromagnetic waves (such as ultraviolet rays and infrared rays).

  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 reversing unit 9 is a unit for temporarily winding a continuous sheet that has been printed on the front (front) surface when performing double-sided printing, and reversing the front and back. The reversing unit 9 is a path (loop path) (referred to as a second path) from the drying unit 8 through the decurling unit 2 to the printing unit 4 for supplying the sheet that has passed through the drying unit 8 to the printing unit 4 again. It is provided on the way. The reversing unit 9 includes a winding rotary body (drum) that rotates to wind the sheet. The continuous sheet that has been printed on the surface and has not been cut is temporarily wound around the winding rotary member. When the winding is completed, the winding rotary member rotates in the reverse direction, 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. More specific operation of duplex printing will be described later.

  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, a path switching mechanism having a movable flapper is provided at a branch position of the path.

  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 is a unit for sorting printed sheets for each group as necessary. The sorted sheets are discharged to the discharge unit 12 including a plurality of trays. In this way, the third path has a layout that passes below the sheet supply unit 1 and discharges the sheet to the opposite side of the printing unit 4 and the drying unit 8 across the sheet supply unit 1.

  The humidifying unit 20 is a unit for generating humidified gas (air) and supplying it between the print head 14 of the printing unit 4 and the sheet. Thereby, the ink drying of the nozzle of the print head 14 is suppressed. As the humidifying method of the humidifying unit 20, a vaporization method, a water spray method, a steam method, or the like is adopted. As the vaporization type, there are a moisture permeable membrane type, a dropping permeation type, a capillary type and the like in addition to the rotation type of the present embodiment. The water spray type includes an ultrasonic type, a centrifugal type, a high-pressure spray type, and a two-fluid spray type. The steam type includes a steam piping type, an electric heating type, and an electrode type. The humidifying unit 20 and the printing unit 4 are connected by a first duct 21, and the humidifying unit 20 and the drying unit 8 are further connected by a second duct 22. The drying unit 8 generates a humid and high-temperature gas when the sheet is dried. This gas is introduced into the humidifying unit 20 through the second duct 22 and used as auxiliary energy for generating a humidified gas in the humidifying unit 20. The humidified gas generated in the humidifying unit 20 is introduced into the print unit through the first duct 21.

  The control unit 13 is a unit that controls each unit of the entire printing apparatus. The control unit 13 includes a CPU, a storage device, a controller (control unit) 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 the concept of the control unit 13. 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. A CPU 201 (central processing unit) controls the operation of each unit of the printing apparatus in an integrated manner. The ROM 202 stores programs executed by the CPU 201 and fixed 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 (hard disk) can store and read programs 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 and a touch panel, and an output unit such as a display for presenting information and a sound generator. For example, a display with a touch panel is used, and the operation status, printing status, maintenance information (remaining ink amount, remaining sheet amount, maintenance status, etc.) of the apparatus are displayed to the user. The user can input various information from the touch panel.

  A dedicated processing unit is provided for units that require high-speed data processing. 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 and the humidification unit 20. 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 printer 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 basic operation during printing will be described. Since the printing operation differs between the single-sided printing mode and the double-sided printing mode, each will be described.

  FIG. 3 is a diagram for explaining the operation in the single-sided printing mode. A conveyance path from the time when the sheet supplied from the sheet supply unit 1 is printed and discharged to the discharge unit 12 is indicated by a bold line. The sheet supplied from the sheet supply unit 1 and processed by the decurling unit 2 and the skew feeding correction unit 3 is printed on the front surface (first surface) by the printing unit 4. An image having a predetermined unit length (referred to as a unit image) in the transport 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 sheet is sequentially discharged and stacked on the discharge unit 12 of the sorter unit 11 via the discharge conveyance 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. 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.

  FIG. 4 is a diagram for explaining the operation in the duplex printing mode. 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 one-sided printing operation described above. The cutter unit 6 is conveyed to the drying unit 8 as a continuous sheet without performing a cutting operation. After the ink is dried on the surface in the drying unit 8, the sheet is guided to the path (second path) on the reversing unit 9 instead of the path (third path) on the discharge conveyance unit 10 side. 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 conveying 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, the continuous sheet remaining on the upstream side in the conveying direction (on the printing unit 4 side) with respect to the cutting position is not supplied to the decurling unit 2 at the sheet leading end (cutting position). 1 and the sheet is wound on roll R1 or R2. By this rewinding, collision with the sheet supplied again in the following back surface printing sequence is avoided.

  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 sequentially discharged and stacked on the discharge unit 12 of the sorter unit 11 via 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.

  Next, the printing unit 4 in the printer having the above configuration will be described in more detail. FIG. 5 is a configuration diagram of the printing unit 4. In the printing unit 4, the sheet S is conveyed in the direction of arrow A in the figure by three types of roller pairs, a first roller pair, a second roller pair, and a third roller pair. The first roller pair is a roller pair including a conveying roller 101 having a driving force and a pinch roller 102 that is driven to rotate. The pinch roller is configured to generate a pressing force in the direction of the conveying roller with a spring (not shown), and good conveying accuracy in the printing unit can be secured with a pressing force in the range of 10 to 20 kgf. The second roller pair indicates each roller pair (seven sets) including a plurality of conveying rollers 103a to 103g having a driving force and a plurality of pinch rollers 104a to 104g that are driven to rotate. The third roller pair is a roller pair including a conveying roller 105 having a driving force and a pinch roller 106 that is driven to rotate. The pinch roller pressing force of the second roller pair and the third roller pair is set to about 1 kgf. The transport roller 101 is provided with a rotary encoder 109 for detecting the roller rotation state.

  In the print area 110 downstream of the first conveying roller pair, seven line type print heads 14a to 14g corresponding to the respective colors are arranged along the sheet conveying direction. The line type print heads 14a to 14g and the pinch rollers 104a to 104g are alternately arranged one by one. Platens 112a to 112g are provided at positions facing the print heads 14a to 14g, respectively, and support the sheet S. At each of the opposed positions of the print heads 14a to 14g, the sheet S is nipped by a pair of rollers and supported by a platen, so that the sheet conveyance behavior is stabilized. In particular, when a sheet is first introduced, the leading end of the sheet passes through a plurality of nip positions in a short cycle, so that floating of the leading end of the sheet is suppressed and stable sheet introduction is performed.

  Reference numeral 156 denotes a loop region for forming a loop shape on the sheet, and reference numeral 157 denotes a loop guide for controlling the loop shape. On the downstream side in the vicinity of the loop region 156, meandering correction guides 153 and 154, which are a pair of end guide members, are arranged at two locations so as to face both ends of the sheet. The meandering correction guide 153 abuts at least one side edge of the sheet and guides the sheet edge. Further, on the downstream side in the vicinity thereof, sheet edge sensors 151 and 152 serving as sheet edge detecting means for detecting the edge position of the sheet are provided. The configuration of the meandering correction guide and the sheet edge sensor will be described in more detail with reference to FIG. The meandering correction guides 153 and 154 are provided with abutting surfaces 153a and 154a which are lower surface guide means for abutting against the sheet end portion and preventing meandering. Also provided are guide surfaces 153b and 154b for guiding the lower surface of the sheet. The sheet edge sensors 151 and 152 are infrared transmission position detection sensors. Infrared light is emitted from the light emitting units 151b and 152b, and the position of the sheet edge is detected based on the amount of light received by the light receiving units 151a and 152a. Reference numeral 155 denotes a movement guide for moving the sheet edge sensors 151 and 152 and the meandering correction guides 153 and 154 in the sheet width direction. The moving guide is composed of a lead screw (not shown) and a drive motor. The meandering correction guide 153 and the sheet edge sensor 151 are integrally fixed, and can be moved integrally to an arbitrary position by the movement guide 155. The sheet end contact surface 153a of the meandering correction guide 153 and the sensor portions 151a and 151b of the sheet edge sensor 151 are assembled while measuring their positions, and the distance is assembled with almost no error. The meandering correction guide 154 and the sheet edge sensor 152 arranged at the opposite end of the sheet have the same configuration. The meandering correction guide is adjusted so as to be perpendicular to the first conveying roller pair. Since the first conveying roller pair has the highest sheet conveying force and has a dominant influence on the conveying accuracy, extremely large meandering correction in the conveying direction is performed by adjusting the perpendicularity of the meandering correction guide. Therefore, it is possible to convey with high accuracy without difficulty.

  Reference numerals 160 and 161 denote second sheet edge sensors which are second sheet edge detection means for detecting the sheet edge position. Reference numeral 185 denotes a second movement guide that allows the second sheet edge sensor to move to an arbitrary position in the sheet width direction. Reference numeral 170 denotes a scanner, reference numerals 172 and 174 denote scanner rollers for conveying the sheet before and after the scanner, and reference numerals 171 and 173 denote pinch rollers for pressing the sheet. Reference numeral 175 denotes a second loop region for forming a loop on the sheet between the scanner 170 and the cutter 182. Reference numeral 176 denotes a second loop guide for controlling the loop shape. Reference numerals 177 and 178 denote second meandering correction guides that are second end guide members that contact at least one side edge of the sheet and guide the sheet edge. Reference numeral 179 denotes a third movement guide for moving the second meandering correction guide to an arbitrary position in the sheet width direction. Reference numeral 181 denotes a pre-cutter conveying roller disposed downstream of the second meandering correction guide, and 180 denotes a pinch roller for pressing the sheet. FIG. 7 is a schematic diagram of the configuration of the control means. The controller 300 has a ROM, a RAM, and a CPU. The sensor unit 310 is a sensor group for detecting the state of the apparatus. Reference numeral 301 denotes a conveyance roller motor for driving each conveyance roller that conveys a sheet, and 302 denotes a pinch roller release motor that is a nip release mechanism that performs a pinch roller release operation to release the nip pressure of the conveyance roller. A motor 303 is a guide moving means for moving the meandering correction guide. The motor 303 also serves as second guide moving means for moving the second guide member and second sheet detecting section moving means for moving the second sheet end detecting means. Reference numeral 304 denotes a motor for moving the second sheet edge sensor. Reference numeral 305 denotes a motor for operating the cutter. Each motor is controlled by each motor driver.

  The sheet conveying operation in the above configuration will be described. The meandering correction operation is described in the flowchart of FIG. After the sheet S supplied from the sheet supply unit 1 creates a loop in the loop unit 156, the sheet S passes through the meandering correction guide pair 153, 154, and is predetermined in the order of the third roller pair, the first roller pair, and the second roller pair. Nipped at the nipping position of the sheet. The conveyance paths from the first roller pair to the third roller pair and the meandering correction guide pairs 153 and 154 are linear and substantially on the same plane. The straight line here is not limited to a strict straight line, but includes a form that is almost a straight line.

  Here, the meandering correction guides 153 and 154 are initially waiting at a position separated from the sheet end as shown in FIG. After the leading edge of the sheet passes through the meandering correction guide, the sheet edge sensors 151 and 152 detect the sheet edge in step S1. Next, the process proceeds to step S2, and the control means determines the amount of movement for just contacting the meandering correction guides 153 and 154 to the sheet end based on the sheet end position detection result. Then, by moving the determined amount of movement, the meandering correction guides 153 and 154 are moved to a position where they abut against the sheet edge (FIG. 6A). As described above, since the meandering correction guides 153 and 154 and the sheet edge sensors 151 and 152 are moved together, the position of the sheet end and the meandering correction guides 153 and 154 can be accurately adjusted. is there. Therefore, it is possible to prevent the buckling and deformation of the sheet due to excessive pushing of the sheet end by the meandering correction guides 153 and 154. Further, since the gap between the sheet end and the meandering correction guides 153 and 154 is excessively opened, the meandering correction effect is not lowered.

  Thereafter, the sheet front end is conveyed by a pair of conveying rollers in the printing unit. Here, in order to convey the sheet along the meandering correction guides 153 and 154 facing the force to meander the sheet, the sheet rotates with the meandering correction guides 153 and 154 as fulcrums. A configuration that facilitates is optimal. In this configuration, a loop portion 156 is provided on the upstream side of the meandering correction guides 153 and 154. Since the sheet can freely move in the sheet width direction to some extent at the loop portion, the sheet on the downstream side of the meandering correction guides 153 and 154 can be rotated. Therefore, even when a force to meander the sheet is applied, the sheet can be easily conveyed along the meandering correction guides 153 and 154. In order to increase the feeding accuracy in the sheet conveying direction, it is effective to increase the pressing force of the conveying roller. In this configuration, the equal pressure is applied, but for the reason described above, it is possible to achieve both the meandering correction. If the pressing force (nip force) of the transport roller is set low to facilitate meander correction, or if the nip is released during transport, the accuracy in the transport direction will deteriorate even if the meander can be corrected. Therefore, it is not preferable. The force that causes meandering by the conveying roller pair includes, for example, non-uniformity of the pressing force of the pinch rollers in the sheet width direction and cylindricity (outer diameter error) of each roller in the sheet width direction. Unlike this configuration, if a pair of conveying rollers is also installed on the upstream side of the meandering correction guides 153 and 154, the sheet is restrained on both the upstream side and the downstream side of the meandering correction guide, and the sheet by the meandering correction guides 153 and 154 The posture cannot be changed. As a result, depending on the type of the sheet to be used, there may be a problem that the sheet buckles or the end portion is broken. This is particularly likely when the sheet rigidity is low.

  When the leading edge of the sheet passes through the print area 110, the position of the sheet edge is detected by the second sheet edge sensors 160 and 161 in step S3. In step S4, the control means determines the amount of movement for moving the second meandering correction guides 177 and 178 to a position that matches the sheet edge based on the detection result. Then, the second meandering correction guides 177 and 178 are moved by the determined amount of movement, and the second meandering correction guides 177 and 178 are moved to positions that match the sheet end. After passing through the scanner 170, the sheet leading edge creates a loop in the downstream loop portion 175 and is conveyed between the second meandering correction guides 177 and 178 that match the sheet width. Thereafter, the sheet is conveyed by a pair of pre-cutter rollers 180 and 181, and the sheet is cut into a desired size by a cutter 182 as necessary. Note that the second sheet edge sensors 160 and 161 and the second meandering correction guides 177 and 178 may be configured to be integrally movable by disposing them at close positions as in the configuration on the upstream side of the print region. As described above, since the positions of the second meandering correction guides 177 and 178 are aligned with the sheet end based on the detection result of the second sheet edge sensor, the guide positioning error with respect to the sheet can be reduced, and good meandering correction is possible. It becomes. In an apparatus having a plurality of heads and a wide print area as in this configuration, a second meandering correction guide is also arranged on the downstream side of the print area, and the behavior of the sheet is controlled before and after the print area. Higher meandering correction effect can be expected. Further, since the second meandering correction guides 177 and 178 are provided on the upstream side in the vicinity of the cutter 182, the meandering when the sheet is cut can be reduced, and good sheet cutting accuracy can be secured. Further, since the second loop portion 175 is disposed on the upstream side in the vicinity of the second meandering correction guides 177 and 178, and the conveyance roller pair 180 and 181 is disposed on the downstream side, the sheet is not buckled or the same as the upstream side of the printing area. Good meandering correction can be performed without causing breakage.

  Next, the operation when the sheet is conveyed in the direction opposite to the normal conveyance direction (the direction opposite to A) in order to rewind the sheet will be described with reference to the flowchart of FIG. First, in step S11, the pinch roller 102 of the first roller pair is separated from the conveying roller 101 to release the nip. In this configuration, the nip force of the first roller pair located on the most upstream side of the print head is significantly higher than the other nip forces. Therefore, by releasing the nip by the nip releasing mechanism, the sheet can be conveyed without buckling, wrinkling or folding even when the sheet end is guided by the meandering correction guides 153 and 154 during the backward conveyance. In step S12, the second meandering correction guides 177 and 178 are retracted to a position separated from the sheet end. During reverse rotation, it is sufficient that the meandering and buckling do not occur. Therefore, it is sufficient to guide only by the meandering correction guides 153 and 154 on the upstream side. In this state, the process proceeds to step S13, and the transport rollers 101, 103, 105 are driven in reverse. When driven by a predetermined amount, each of the transport rollers 101, 103, 105 is stopped in step S14.

  In the above embodiment, the print unit 4 is provided with line-type print heads for the respective colors. However, for example, a serial type single print head other than this configuration can be similarly configured. Further, the meandering correction guide may be configured such that one side contacting the sheet end is pressed toward the sheet end by an elastic member such as a spring. In this case, a slight positioning error of the meandering correction guide with respect to the sheet end portion can be absorbed depending on the sheet type, and the margin for sheet buckling is further increased. The meandering correction guide can be effective only on one side with respect to the sheet end. What is necessary is just to take the structure which always presses a sheet | seat to one side with a skew roller.

  The printing apparatus according to the embodiment described above is provided with a pair of conveying rollers for nip-conveying a sheet on the upstream side of the printing unit 4, further provided with a sheet edge sensor and a meandering correction guide on the further upstream side, and further looped near the upstream side thereof. The arrangement relationship is provided. Further, a sheet edge sensor and a meandering correction guide are also provided on the print portion flowable side, and a loop portion is provided in the vicinity of the upstream side of the meandering correction guide. With this configuration, the following effects can be obtained.

(1) The meandering correction can be performed with high accuracy even if the nip force of the conveying roller pair on the downstream side of the meandering correction guide is set high. Therefore, it is possible to achieve both high levels of roll paper conveyance accuracy and meandering correction accuracy.
(2) The meandering correction guide can be brought into contact with the sheet end portion with high accuracy. Therefore, accurate meandering correction can be performed without causing the sheet to buckle, bend or wrinkle.
(3) Since the print area, the pair of conveying rollers and the meandering correction guide pair in the vicinity thereof are arranged on a substantially plane, the print area is hardly affected by the stiffness of the sheet. Therefore, it is relatively easy to control the sheet with high accuracy. Therefore, good printing accuracy can be ensured.
(4) By providing a meandering correction guide on the downstream side of the print area and guiding it upstream and downstream of the print area, good meandering correction accuracy can be maintained even when the print area is wide.
(5) Since the meandering correction guide is arranged on the upstream side of the cutter unit, good cutting accuracy can be secured. As a result, good print quality can be maintained.

  From the above (1) to (5), it is possible to achieve both a sheet conveyance accuracy and a meandering correction accuracy at a high level, and a dimensional printing apparatus with high print quality is provided.

DESCRIPTION OF SYMBOLS 4 Print part 13 Control part 101 Conveyance roller 102 Pinch roller 156 Loop part 153,154 Meander correction guide 151,152 Sheet edge sensor

Claims (8)

A print head that prints on a sheet; a conveyance roller that is arranged upstream of the print head in the sheet conveyance direction and conveys the sheet; and a loop that is arranged upstream of the conveyance roller in the sheet conveyance direction. A printing apparatus comprising: a loop region; and a guide member that is disposed between the conveyance roller and the loop region and has a contact surface that contacts a side edge of a sheet and is movable in a direction intersecting the sheet conveyance direction.
The guide member has a sensor for detecting the side edge of the sheet, and is arranged at a position where the contact surface and the side edge of the sheet are separated from each other before the side edge of the sheet is detected by the sensor. When the side edge of the sheet is detected by the sensor, the printing apparatus is moved to a position where the abutting surface and the side edge of the sheet abut.   The printing apparatus according to claim 1, wherein the guide member is provided on both side edges of the sheet.   A second guide member is provided on the downstream side of the print head in the sheet conveying direction and has a second contact surface that contacts the side edge of the sheet and is movable in a direction intersecting the sheet conveying direction. The printing apparatus according to claim 1, wherein the printing apparatus is a printer.   The second guide member has a second sensor for detecting a side edge of the sheet, and the second sensor detects the side edge of the sheet before the side edge of the sheet is detected by the second sensor. When the side edge of the sheet is detected by the second sensor, the sheet is moved to a position where the second contact surface and the side edge of the sheet are in contact with each other. The printing apparatus according to claim 3, wherein the printing apparatus is a printing apparatus.   The printing apparatus according to claim 4, further comprising a second loop region disposed between the print head and the second guide member and forming a loop on the sheet.   The printing apparatus according to claim 5, wherein the sheet is a continuous sheet, and further includes a cutter that is disposed on the downstream side of the second guide member in the sheet conveyance direction and cuts the sheet.   The printing apparatus according to claim 6, wherein the second guide member is moved to a position where the contact surface and the side edge of the sheet are separated from each other when the sheet is conveyed in the reverse direction.   The printing apparatus according to claim 1, wherein the print head is a line head in which a nozzle row for ejecting ink in a direction intersecting the sheet conveyance direction is formed. .

Images