Image forming device

Abstract

To prevent loss of convenience for a user when a skew occurs in a recording medium.SOLUTION: An image forming device 80 includes: a cutter unit 76 that cuts a rolled sheet Pr serving as a long recording medium; a skew amount calculation part 308 that calculates a skew amount θ of the sheet Pr; and a skew response unit 30 that adjusts the cutting direction of the cutter unit 76 with respect to a conveying direction T of the sheet Pr in accordance with the skew amount θ.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] In paper feeding in an image forming device that uses roll paper as the recording medium, a technique is already known in which intermittent transport is performed by driving rollers to transport the roll paper, and during this process, a speed difference is generated between multiple transport rollers while accelerating the roll paper to a target speed, and skew correction is performed by adjusting the tension.

[0003] Patent Document 1 discloses a configuration in which, for the purpose of correcting skew in roll paper, intermittent transport is performed by driving rollers, and the transport rollers are decelerated while the roll paper is being accelerated to a target speed. Summary of the Invention [Problem to be solved by the invention]

[0004] However, with conventional skew correction methods, the tension can vary depending on the thickness and material of the roll paper, making it impossible to completely correct the skew. In such cases, it is deemed a paper feed error and the user must be asked to reset the settings.

[0005] An object of the present invention is to prevent a loss of convenience for users when skew occurs in a recording medium. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, an image forming apparatus according to one aspect of the present invention includes a cutting unit that cuts a long recording medium, a skew amount calculation unit that calculates a skew amount of the recording medium, and an adjustment unit that adjusts the cutting direction of the cutting unit relative to the transport direction of the recording medium in accordance with the skew amount. Effect of the Invention

[0007] This makes it possible to prevent the loss of convenience for users when skew occurs in the recording medium. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of an example of a schematic configuration of an image forming apparatus according to an embodiment; [Diagram 2] FIG. 2 is a side cross-sectional view of the image forming apparatus shown in FIG. 1. [Diagram 3] FIG. 2 is a perspective view of a carriage-related element of the image forming apparatus; [Figure 4] FIG. 1 is a perspective view showing an example of a schematic configuration of a drive mechanism of a cutter unit; [Diagram 5] FIG. 1 is a functional block diagram illustrating an example of functions of a paper feed device applied to an image forming apparatus according to an embodiment. [Figure 6] FIG. 1 is a diagram showing an example of a schematic configuration of a skew support unit according to an embodiment of the present invention; [Figure 7] FIG. 13 shows an example of the operation of the skew correction unit when the paper is skewed to the left in the figure. [Figure 8] FIG. 13 shows an example of the operation of the skew correction unit when the paper is skewed to the right in the figure. [Figure 9] FIG. 9 is a diagram for explaining an example of the operation of the cutter unit in the example of FIG. 8; [Figure 10] FIG. 13 shows a modified example of the skew compensation unit; [Figure 11] A functional block diagram relating to skew correction control of the present embodiment. [Figure 12] Hardware configuration diagram of the control unit [Figure 13] 1 is a flowchart of a conventional skew correction control as a comparative example. [Figure 14] 1 is a flowchart of a skew correction control performed in an image forming apparatus according to an embodiment of the present invention. [Figure 15] 11 is a flowchart of a subroutine process of skew correction in step S103. [Figure 16] 1 is a flowchart of a subroutine process for measuring the amount of skew in steps S201 and S204. [Figure 17]Flowchart of subroutine process of cutter angle adjustment in step S206 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment will be described with reference to the accompanying drawings. In order to facilitate understanding of the description, the same components in each drawing are denoted by the same reference numerals as much as possible, and duplicated description will be omitted.

[0010] An example of the overall configuration of an image forming apparatus 80 according to an embodiment of the present invention and an example of the configuration of each part will be described with reference to Figs. 1 to 4. Fig. 1 is a perspective view of a schematic configuration example of the image forming apparatus 80 according to the embodiment. Fig. 2 is a side cross-sectional view of the image forming apparatus 80 shown in Fig. 1. Arrow X shown in Fig. 1 indicates the depth direction (front-rear direction) of the image forming apparatus 80. Arrow Y indicates the width direction (main scanning direction) of the image forming apparatus 80. Arrow Z indicates the up-down direction of the image forming apparatus 80. Note that similar arrows X, Y, and Z are appropriately illustrated in Fig. 2 and subsequent figures. The side cross-sectional view of Fig. 2 is a cross-sectional view of the image forming apparatus 80 in the Y direction at approximately the center in the Y direction along a plane perpendicular to the Y direction (a plane parallel to the X direction and the Z direction).

[0011] The image forming apparatus 80 according to this embodiment has a paper feeder. The paper feeder feeds paper Pr from rolls of paper Pa and Pb. The rolls of paper Pa and Pb are recording media formed by winding long sheets of paper (also called "sheets") into a roll.

[0012] In this embodiment, an inkjet printer that prints on a recording medium by ejecting ink droplets corresponding to image data will be described as an example of the image forming apparatus 80. However, a copying machine or a printing machine using an electrophotographic method or the like that conveys a recording medium and prints can also be applied as the image forming apparatus according to this embodiment.

[0013] 1, image forming apparatus 80 is a serial type liquid ejection type (ink ejection type) image forming apparatus, and a main body housing 81 is disposed on a main body frame 82. An image forming unit 60 is installed inside the main body housing 81. In the image forming apparatus 80, a main guide rod 64 and a sub guide rod 65 are stretched in the main scanning direction indicated by a double arrow Y in FIG. 1 within the area of ​​the image forming unit 60 inside the main body housing 81. The main guide rod 64 movably supports a carriage 66, and the carriage 66 is provided with a connecting piece 66a that engages with the sub guide rod 65 to stabilize the position of the carriage 66.

[0014] In the image forming device 80, an endless timing belt 67 is disposed along a main guide rod 64, and the timing belt 67 is stretched between a drive pulley 68 and a driven pulley 69. The drive pulley 68 is rotationally driven by a main scanning motor 70, and the driven pulley 69 is disposed in a state in which it applies a predetermined tension to the timing belt 67. The drive pulley 68 is rotationally driven by the main scanning motor 70, thereby rotating and moving the timing belt 67 in the main scanning direction according to the rotation direction of the main scanning motor 70.

[0015] The carriage 66 is connected to a timing belt 67, and as the timing belt 67 is rotated in the main scanning direction by a drive pulley 68, the carriage 66 reciprocates in the main scanning direction along the main guide rod 64.

[0016] In the image forming apparatus 80, a cartridge unit 71 and a maintenance mechanism unit 72 are detachably housed at an end position in the main scanning direction inside a main body housing 81. Cartridges that respectively contain yellow (Y), magenta (M), cyan (C), and black (K) inks are housed in a replaceable manner in the cartridge unit 71. Each cartridge in the cartridge unit 71 is connected by a pipe to the recording head of the corresponding color among the recording heads (see FIG. 3) mounted on the carriage 66, and ink is supplied from the cartridge unit 71 to the recording head of each color through the pipe.

[0017] The image forming device 80 records an image on a paper Pr (recording medium) by ejecting ink onto the paper Pr, which is intermittently transported in a sub-scanning direction (X direction) perpendicular to the main scanning direction over a platen (plate) 74 shown in FIG. 2, while moving a carriage 66 in the main scanning direction (Y direction).

[0018] The paper Pr is not limited to paper, and various types of recording media such as rolled film can be used. However, in the following explanation, for clarity, the paper being transported will be referred to as paper Pr, the rolled state of the paper Pr will be referred to as roll paper Pa, Pb, and the core tube (core portion) of the roll paper Pa, Pb will be referred to as Ps.

[0019] As shown in FIG. 2, the image forming device 80 has a chamber 75 with a fan disposed below the platen 74, and by driving the fan, the paper Pr transported over the platen 74 is transported in close contact with the platen 74.

[0020] The image forming device 80 intermittently transports the paper Pr in the sub-scanning direction, and while the transport of the paper Pr in the sub-scanning direction is stopped, the carriage 66 is moved in the main scanning direction and ink is ejected from the nozzle row of the recording head mounted on the carriage 66 onto the paper Pr on the platen 74, thereby forming (recording) an image on the rolled paper Pr.

[0021] The maintenance mechanism 72 cleans the ejection surface of the print head inside the carriage 66, caps it, ejects unnecessary ink, etc., in order to remove unnecessary ink from the print head and maintain the reliability of the print head.

[0022] FIG. 3 is a perspective view of elements related to the carriage 66 in the image forming apparatus 80. As shown in FIG. 3, in the image forming apparatus 80, a main scanning encoder sheet 401 is arranged parallel to the timing belt 67 and the main guide rod 64, at least over the moving range of the carriage 66. A main scanning encoder sensor 402 for reading the main scanning encoder sheet 401 is attached to the carriage 66. The image forming apparatus 80 controls the movement of the carriage 66 in the main scanning direction as shown by the arrow A in FIG. 3 by controlling the drive of the main scanning motor 70 based on the reading result of the main scanning encoder sheet 401 by the main scanning encoder sensor 402, and controls the position of the carriage 66 in the main scanning direction as shown by the dotted line in FIG. 3. The position of the home position of the carriage 66 in the main scanning direction is determined based on, for example, one end position of the carriage 66 in the main scanning direction (for example, a place where the carriage 66 is in contact with a plate material or the like arranged at the right end of the image forming unit 60 in FIG. 1, or the position of the carriage 66 shown by the solid line in FIG. 3).

[0023] Furthermore, the image forming device 80 detects both ends of the paper Pr conveyed to the image forming unit 60 by a reflective sensor (encoder sensor, paper edge sensor) 403 mounted on the carriage 66, and detects the size of the paper Pr from the main scanning direction position read by the paper edge sensor 403. The paper edge sensor 403 moves over the paper Pr together with the carriage 66, and detects the positions of the paper edges and the paper width.

[0024] 1, in an image forming apparatus 80, two spool bearing pedestals 5a and 5b are provided side by side in the Z direction on a main body frame 82 that supports a main body housing 81. Rolls of paper Pa and Pb are rotatably mounted on the spool bearing pedestals 5a and 5b, respectively.

[0025] The paper (rolled paper) Pr pulled out from the tip of the roll paper Pa, Pb set on the spool bearing bases 5a, 5b is transported within the transport path 9 by the transport roller pairs 6a, 6b, the registration roller 10, and the registration pressure roller 17, as shown by the arrows in Figure 2.

[0026] The control unit 100 controls the driving devices 7a and 7b to rotate the conveying roller pairs 6a and 6b, the registration roller 10, the registration pressure roller 17, and the like.

[0027] Under the rolls of paper Pa, Pb, roll paper receiving trays 8a, 8b are provided to prevent the rolls of paper Pa, Pb from falling.

[0028] 2, a sensor 93 is provided on each of the roll paper receiving pedestals 8a, 8b. Each sensor 93 can detect whether roll paper Pa, Pb is placed on the spool bearing pedestal 5a, 5b. The sensor 93 is communicatively connected to the control unit 100, and outputs detection information regarding the presence or absence of roll paper Pa, Pb to the control unit 100.

[0029] The paper Pr passes through a transport path 9 supported by medium transport guide members 18a, 18b, etc., and is transported onto a platen 74 in the image forming unit 60. When images are formed on both sides of the paper Pr, the print surface of the paper Pr is reversed in the reversing unit 19.

[0030] In the image forming section 60, an image is formed by a liquid recording head discharging droplets of each color onto paper Pr in accordance with image data. As shown in Fig. 2, a cutter unit 76 (cutting section) extending in the sub-scanning direction (paper width direction) is provided at the forward transport direction discharge section of paper Pr on which an image has been formed, and is used to cut paper Pr, which is made of continuous paper, to a predetermined length.

[0031] In order to align the leading edge of the transported continuous paper, the cutter unit 76 is fixed to a wire or timing belt stretched between multiple pulleys (one of which is connected to a drive motor), and cuts the paper Pr to a predetermined length by being moved in the main scanning direction Y by the drive motor. The cut paper Pr is discharged to a discharge section.

[0032] FIG. 4 is a perspective view showing an example of a schematic configuration of a drive mechanism of the cutter unit 76. The shuttle 201 is fastened to a drive belt 202. The drive belt 202 is stretched between two pulleys 204a and 204b as shown in FIG. 4. The two pulleys 204a and 204b both have an axis of rotation in the X direction and are spaced apart in the Y direction. The distance in the Y direction between the pulleys 204a and 204b is set to be larger than the maximum width of the paper Pr that can be used in the image forming apparatus 80. The drive belt 202 is connected to a cutter drive motor 203 via one pulley 204a and a gear system, and can move between the two pulleys 204a and 204b by the drive force transmitted from the cutter drive motor 203.

[0033] When cutting the paper Pr, the cutter unit 76 starts rotating the cutter drive motor 203, and drives the drive belt 202 as shown by the arrow B in accordance with the rotation of the cutter drive motor 203. This drives the shuttle 201 connected to the drive belt 202 in a direction perpendicular to the conveyance direction of the paper Pr (the direction of the arrow T shown in FIGS. 1 and 3) as shown by the arrow C, i.e., in the main scanning direction (Y direction).

[0034] The shuttle 201 is provided with circular blades 200a and 200b. The circular blades 200a and 200b are installed so as to be rotatable around axes along the X direction. The circular blades 200a and 200b are arranged in line in the Z direction so that the rotation axes are at the same position in the Y direction. The circular blades 200a and 200b are formed to have approximately the same diameter, and are arranged so that the distance between the rotation axes is approximately the same as the diameter. With this configuration, the paper Pr can be inserted between the blades on the outer edges of the circular blades 200a and 200b, and each blade can come into contact with the paper Pr to cut it. The circular blades 200a and 200b move in the direction indicated by the arrow C together with the drive of the shuttle 201, and cut the paper Pr by rotating while sandwiching the paper Pr between the circular blades 200a and 200b.

[0035] Although FIGS. 1 and 2 show an example of the configuration of an image forming apparatus in which rolled papers Pa and Pb can be set on two spool bearing pedestals 5a and 5b, the image forming apparatus may be provided with one spool bearing pedestal.

[0036] In the above explanation, the configurations corresponding to the two rolls of paper Pa and Pb were described using the identifiers a and b (for example, spool bearing stands 5a and 5b), but hereinafter, the identifiers a and b will not be used unless a distinction is made.

[0037] Next, control of functions related to paper feeding of the image forming apparatus 80 will be described with reference to Fig. 5. Fig. 5 is a functional block diagram illustrating an example of functions of a paper feeding device applied to the image forming apparatus 80 of the embodiment.

[0038] The control unit 110 controls the entire sheet feeding device. In Fig. 5, an example of a functional block in which the control unit 110 controls the sensor 93 and the motor drive circuit units 120 and 140 is shown, and other functional blocks are omitted. Note that the control unit 110 may be configured as a part of the control unit 100 shown in Fig. 2.

[0039] The control unit 110 includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory). The CPU executes various programs and controls the entire image processing device based on arithmetic processing and control programs. The RAM is a volatile storage medium for reading and writing information at high speed, and functions as a work area when the CPU executes a program. The ROM is a read-only non-volatile storage medium in which various programs and control programs are stored.

[0040] The motor drive circuit unit 120 drives a motor under the control of the control unit 110 , and drives the roll paper drive unit 130 .

[0041] The roll paper drive unit 130 rotates the rolled paper Pa, Pb in the forward or reverse direction. The roll paper drive unit 130 uses, for example, a roll paper rotation motor. The roll rotation motor is a drive source that imparts a rotational drive force to the rolled paper Pa, Pb, and is connected, for example, to the core Ps of the rolled paper Pa, Pb. The roll rotation motor can be implemented, for example, as part of the drive devices 7a, 7b shown in FIG. 2.

[0042] The motor drive circuit unit 140 drives a motor under the control of the control unit 110 , and drives the transport drive unit 150 .

[0043] The transport drive unit 150 drives the transport unit 160 .

[0044] The transport section 160 is a transport means for transporting the paper, and is, for example, the transport roller pair 6 shown in Fig. 2. The transport section 160 may also include other elements for transporting the recording medium that are arranged on the transport path 9, such as a registration roller 10 arranged immediately before the platen 74 on the upstream side in the transport direction T in Fig. 2, and a registration pressure roller 17 arranged opposite the registration roller 10 and passing the paper Pr through a gap between the registration roller 10 and the registration roller 10.

[0045] Here, in the image forming apparatus 80, a state in which the paper Pr transported through the image forming section 60 is tilted with respect to the transport direction T, that is, so-called skew, may occur. When skew occurs, it may cause problems such as accurate printing at a desired position on the paper Pr, reading of characters or images, or paper jams due to timing discrepancies when switching between transport directions. For this reason, various skew correction techniques have been proposed to eliminate skew in the recording medium when skew occurs.

[0046] Furthermore, when skew occurs, the paper Pr is conveyed obliquely relative to the cutter unit 76, which may result in poor paper cutting, in which the paper Pr is cut obliquely relative to the width direction. In particular, the image forming apparatus 80 of this embodiment includes a skew response unit 30 (adjustment unit) as an element for preventing poor paper cutting when such skew occurs. When skew occurs in the paper Pr, the skew response unit 30 tilts the entire cutter unit 76 described with reference to FIG. 4 in the conveying direction T, the X direction, and the Y direction. The amount of tilt is adjusted according to the skew angle. This allows the skew angle of the paper Pr to be aligned with the paper cutting direction of the cutter unit 76, so that even if skew occurs, the paper Pr can be prevented from being cut obliquely relative to the width direction.

[0047] Fig. 6 is a diagram showing an example of a schematic configuration of the skew compensation unit 30 according to this embodiment. As shown in Fig. 6, the skew compensation unit 30 has an angle adjustment motor 300, a shaft 301, an encoder 302, a rotation amount sensor 303, a slide block 304, a cutter rotation axis 305, and a home position sensor 306.

[0048] In this embodiment, a configuration in which the angle of the cutter unit 76 is adjusted by combining gears is exemplified. However, other mechanisms such as a crank mechanism using a crank disc and a slider, or a Scotch yoke mechanism in which an eccentric disc is rotated to reciprocate a yoke, are also useful.

[0049] The cutter unit 76 is attached so as to rotate about a cutter rotation shaft 305. The cutter rotation shaft 305 is installed along a direction perpendicular to the conveyance direction T, the X direction, and the Y direction, i.e., the Z direction. The cutter rotation shaft 305 is also disposed at a position approximately at the center of the length of the cutter unit 76 (paper cutting direction). This allows the skew support unit 30 to rotate the cutter unit 76 around the Z direction at a position approximately at the center of the length.

[0050] A worm gear 300a is provided on the drive shaft of the angle adjustment motor 300 so as to be rotatable integrally with the drive shaft. A worm gear 301a is also provided on a portion of the circumferential surface of the shaft 301. These two worm gears 300a, 301a mesh with each other. As a result, when the angle adjustment motor 300 rotates, the shaft 301 rotates about its axis via the worm gears 300a and 301a as shown by arrow D in FIG. 6.

[0051] The slide block 304 and the shaft 301 are connected by a screw structure. For example, the shaft 301 is inserted into a through hole provided in the slide block 304, and one of the inner circumferential surface of the through hole and a portion of the circumferential surface of the shaft 301 that can be placed inside the through hole is male-threaded, and the other is female-threaded, and they are engaged with each other. With this configuration, the rotation of the shaft 301 shown by the arrow D causes the slide block 304 to move in the axial direction of the shaft 301 as shown by the arrow E.

[0052] One end of the cutter unit 76 in the Y direction (the right side of the paper in FIG. 6) is connected to the slide block 304. The cutter unit 76 is connected to the slide block 304 so as to be rotatable around an axis in the Z direction. With this configuration, when the slide block 304 moves along the axial direction of the shaft 301, the end of the cutter unit 76 connected to the slide block 304 also moves together with the slide block 304 in the direction indicated by the arrow E. As a result, the cutter unit 76 rotates around the cutter rotation axis 305 (see arrows H and K in FIGS. 7 and 8), and the inclination angle θp (see FIG. 9) is adjusted.

[0053] The home position sensor 306 detects the position (home position) where the longitudinal direction of the cutter unit 76 is perpendicular to the transport direction T, and if no skew occurs, fixes the cutter unit 76 at the home position.

[0054] In the example of Fig. 6, the shaft 301 is disposed so that its axial direction is parallel to the X direction and the conveying direction T. A worm gear 301a is provided at the end of the shaft 301 on the front side in the X direction (the lower side of the paper in Fig. 6), and an encoder 302 is installed at the end on the rear side in the X direction (the upper side of the paper in Fig. 6). The encoder 302 is formed, for example, in a disk shape having a pair of main surfaces on both sides in the X direction. The rotation amount sensor 303 is installed so as to face parts of the radially outer sides of the pair of main surfaces of the encoder 302 from both sides in the X direction.

[0055] 7 and 8, the operation of the skew response unit 30 when skew occurs will be described. When skew occurs, the angle adjustment motor 300 is rotated to adjust the tilt angle of the cutter unit 76 according to the amount of skew. An encoder 302 is connected to the shaft 301 and rotates together with the shaft 301. The rotation of this encoder 302 is detected by a rotation amount sensor 303. The skew response unit 30 calculates the tilt angle of the cutter unit 76 based on the number of rotations of the encoder 302 detected by the rotation amount sensor 303, and stops and fixes the angle adjustment motor 300 at an angle according to the amount of skew.

[0056] Fig. 7 is a diagram showing an example of the operation of skew support unit 30 when skew occurs such that paper Pr is inclined to the left in the figure. In the situation shown in Fig. 7, shaft 301 is rotated in one direction indicated by arrow F by driving angle adjustment motor 300, and slide block 304 is moved on shaft 301 to the front side in the X direction (toward the bottom of the paper in Fig. 7) as indicated by arrow G.

[0057] As a result, as shown by arrow H, cutter unit 76 rotates clockwise on cutter rotation axis 305, and the longitudinal direction of cutter unit 76 is tilted with respect to transport direction T so that the right side of the paper in the width direction is positioned forward in the X direction. In other words, cutter unit 76 is tilted to the left in the figure, just like paper Pr, so that the width direction of paper Pr and the paper cutting direction by cutter unit 76 are the same direction. This makes it possible to prevent paper Pr from being cut obliquely with respect to the width direction even if the skew shown in FIG. 7 occurs.

[0058] Fig. 8 is a diagram showing an example of the operation of skew compensation unit 30 when skew occurs such that paper Pr is inclined to the right in the figure. In the situation shown in Fig. 8, shaft 301 is rotated in the direction indicated by arrow I (the opposite direction to direction F in Fig. 7) by driving angle adjustment motor 300, and slide block 304 is moved on shaft 301 to the rear side in the X direction (upper side of the paper in Fig. 8) as indicated by arrow J.

[0059] As a result, as shown by arrow K, cutter unit 76 rotates counterclockwise on cutter rotation axis 305, and the longitudinal direction of cutter unit 76 is tilted with respect to transport direction T so that the left side of the paper in the width direction is located forward in the X direction. In other words, cutter unit 76 is tilted to the right in the figure like paper Pr, and the width direction of paper Pr and the paper cutting direction by cutter unit 76 are the same direction. This makes it possible to prevent paper Pr from being cut obliquely with respect to the width direction even if the skew shown in FIG. 8 occurs.

[0060] Fig. 9 is a diagram for explaining an example of the operation of the cutter unit 76 in the example of Fig. 8. As shown in Fig. 9, when image formation is performed by the carriage 66 in a state in which skew occurs in the paper Pr, the image formed on the paper Pr is also inclined with respect to the transport direction T. Here, the amount of inclination of the image is expressed as "image shift amount θp".

[0061] The skew support unit 30 of this embodiment calculates the skew amount θ of the paper Pr by a skew amount measurement process described later with reference to Fig. 16. Then, the calculated skew amount θ and the image shift amount θp are considered to be the same, and the angle adjustment motor 300 is feedback-controlled based on the rotation amount of the encoder 302 detected by the rotation amount sensor 303 so that the inclination angle of the cutter unit 76 is at a position corresponding to the skew amount θ (=image shift amount θp). In this embodiment, the unit of the skew amount θ and the image shift amount θp is the inclination angle with respect to the X direction. As a result, as shown in Fig. 9, the inclination angle of the cutter unit 76 can be made to match the image shift amount θp.

[0062] Thereafter, the paper Pr on which the image with the skew amount θ=image shift amount θp is formed passes through the cutter unit 76 and is cut to the specified length. At that time, the cutter unit 76 adjusts its angle to match the image shift amount θp, so that it is possible to prevent the end of the paper Pr from being obliquely cut.

[0063] 9, the image forming unit 60 can perform control to correct the skew by shifting the image formed on the paper Pr so that the image itself is inclined with respect to the transport direction T according to the skew amount θ of the paper Pr. Details of the technology for correcting the skew by such image shifting are disclosed in, for example, JP 2012-63523 A.

[0064] Fig. 10 is a diagram showing a modified example of the skew compensation unit. The outline of Fig. 10 is similar to that of Fig. 8. The skew compensation unit 30A shown in Fig. 10 differs from the skew compensation unit 30 shown in Fig. 8 etc. in that the cutter rotation shaft 305b is provided at the end of the cutter unit 76 (the end opposite the end connected to the slide block 304, the end on the left side in Fig. 10). As in the modified example shown in Fig. 10, the cutter rotation shaft 305b may be disposed at any position in the paper cutting direction of the cutter unit 76.

[0065] However, it is preferable that the rotation axis of the inclination angle of the cutter unit 76 is disposed approximately in the center of the paper cutting direction of the cutter unit 76, like the cutter rotation axis 305 shown in FIG. 8. In FIG. 10, the configuration of FIG. 8 is illustrated by dotted lines, but when the cutter unit 76 is rotated by the same inclination angle, the amount of movement of the slide block 304 in the axial direction of the shaft 301 can be reduced by a distance L when the cutter rotation axis 305 is rotated around the cutter rotation axis 305 compared to when the cutter rotation axis 305b is rotated around the cutter rotation axis 305b. In this way, compared to when the cutter rotation axis 305b is disposed at the end of the cutter unit 76, when the cutter rotation axis 305 is disposed at the center of the cutter unit 76 in the longitudinal direction, the operating range of the slide block 304 required for adjusting the angle of the cutter unit 76 can be reduced, which is advantageous in that the overall size of the skew adjustment unit 30 can be reduced.

[0066] Next, skew correction control performed in the image forming apparatus 80 of this embodiment will be described with reference to Figures 11 to 17. In the skew correction control of this embodiment, the skew correction unit 30 described with particular reference to Figures 6 to 10 is used to perform control to adjust the inclination angle of the cutter unit 76 with respect to the transport direction T in accordance with the skew angle of the paper Pr.

[0067] Fig. 11 is a functional block diagram relating to the skew correction control of this embodiment. As shown in Fig. 11, the image forming apparatus 80 includes a control unit 307 that performs the skew correction control. The control unit 307 may be configured as a part of the control unit 100 shown in Fig. 2 or the control unit 110 shown in Fig. 5.

[0068] The control unit 307 has a skew amount calculation unit 308, a skew correction unit 309, a cutter angle adjustment unit 310, and a cutter control unit 311 as functional blocks related to skew correction control.

[0069] The skew amount calculation unit 308 calculates the skew amount θ when skew occurs in the paper Pr being conveyed. The skew amount calculation unit 308 executes a skew amount measurement process, which will be described later, with reference to the flowchart in Fig. 16 based on information on the edge position of the paper Pr input from the paper edge sensor 403, to calculate the skew amount θ of the paper Pr. The skew amount calculation unit 308 outputs information on the calculated skew amount θ to the skew correction unit 309 and the cutter angle adjustment unit 310.

[0070] The skew correction unit 309 performs skew correction by the conveying unit 160 based on the skew amount θ of the paper Pr calculated by the skew amount calculation unit 308. The skew correction unit 309 generates a control command for reducing or eliminating the skew amount θ of the paper Pr and outputs it to the conveying unit 160, and performs control such as changing the conveying speed of rollers included in the conveying unit 160. The skew correction unit 309 outputs information on the correction result, such as the presence or absence of skew after the skew correction by the conveying unit 160 and the remaining skew amount θ, to the cutter angle adjustment unit 310.

[0071] The cutter angle adjustment unit 310 controls the operation of the skew response unit 30 to adjust the inclination angle of the cutter unit 76 to an optimal angle. Here, the optimal angle is an inclination angle that does not affect the cutting of the paper Pr by the cutter unit 76 even if the skew of the paper Pr remains after the skew correction by the transport unit 160. The cutter angle adjustment unit 310 generates a control command that can set the inclination angle of the cutter unit 76 to an optimal angle based on various information input from the home position sensor 306 and the rotation amount sensor 303 of the skew response unit 30, and outputs the control command to the angle adjustment motor 300 of the skew response unit 30. In addition, the cutter angle adjustment unit 310 outputs information to the cutter control unit 311 that the adjustment of the inclination angle of the cutter unit 76 by the skew response unit 30 has been completed.

[0072] The cutter control unit 311 controls the operation of the cutter unit 76 to cut the paper Pr.

[0073] Fig. 12 is an example of a hardware configuration diagram of the control unit 307. As shown in Fig. 12, the control unit 307 can be physically configured as a computer device or a circuit board including a CPU (Central Processing Unit) 101, a RAM (Random Access Memory) 102 and a ROM (Read Only Memory) 103 as main storage devices, an input device 104 such as a keyboard and a mouse as input devices, an output device 105 such as a display, a communication module 106 as a data transmission / reception device such as a network card, an auxiliary storage device 107, etc. Each function of the control unit 307 described with reference to Fig. 11 is realized by reading predetermined computer software onto hardware such as the CPU 101 and the RAM 102, operating the communication module 106, the input device 104, the output device 105, etc. under the control of the CPU 101, and reading and writing data in the RAM 102 and the auxiliary storage device 107.

[0074] The hardware configurations of the control unit 100 shown in FIG. 2 and the control unit 110 shown in FIG. 5 are similar to the example configuration shown in FIG.

[0075] First, conventional skew correction control will be described as a comparative example with reference to Fig. 13. Fig. 13 is a flowchart of conventional skew correction control as a comparative example. In conventional skew correction control, only skew correction is performed by the transport unit 160. Each process in the flowchart shown in Fig. 13 is performed by, for example, the control unit 110 shown in Fig. 5.

[0076] When the control unit 110 detects that the rolled papers Pa, Pb have been set in the paper feeder (spool bearing bases 5a, 5b) (S501), it controls the motor drive circuit unit 120 and switches the rolled paper rotation motor included in the rolled paper drive unit 130 to the ON state (S502). This causes the rolled paper rotation motor to rotate the rolled papers Pa, Pb in the forward direction, and the leading edge of the paper Pr of the rolled papers Pa, Pb is sent out to the conveying path 9. At this time, one of the two rolled papers Pa, Pb is driven to rotate, and the rolled paper Pr is pulled out from the one that is driven to rotate. At this time, the motor drive circuit unit 140 rotates the rollers of the conveying unit 160, and the leading edge of the paper Pr sent out from one of the rolled papers Pa, Pb is conveyed along the conveying path 9 inside the device to the image forming unit 60.

[0077] The control unit 110 performs skew correction by the conveying unit 160 (S503). In this step, for example, a control command for reducing or eliminating the skew amount θ of the paper Pr is generated and output to the conveying unit 160, and control is performed to change the conveying speed of rollers included in the conveying unit 160. Note that, for details of the skew correction by the conveying unit 160, a skew correction method by adjusting the tension between the rollers of the conveying unit 160, such as that disclosed in the above-mentioned Patent Document 1 (JP Patent Publication 2012-126527), can be applied.

[0078] In step S504, after the skew correction in step S503, the control unit 110 determines whether or not skew has occurred in the paper Pr in the image forming unit 60. In this step, the presence or absence of skew can be determined by using, for example, a method similar to the skew amount measurement process described later with reference to FIG.

[0079] If no skew has occurred (No in step S504), it is determined that skew correction has been completed, and the process proceeds to step S505, where the leading end of the rolled paper Pr (roll paper) on which the image has been formed by the image forming unit 60 is cut off by the cutter unit 76.

[0080] Then, in step S506, the control unit 110 controls the motor drive circuits 120, 140 to rotate the remaining cut roll paper Pr in the reverse direction along the transport path 9 to rewind it, and move the leading edge of the roll paper Pr to a position where it can be detected by the paper leading edge sensor 403 of the carriage 66. At this position, the control unit 110 controls the motor drive circuits 120, 140 to stop the roll paper rotation motor included in the roll paper drive unit 130 (S506). This stops the roll paper Pr at the print feed position and puts it into a standby state (S507), and this control flow ends.

[0081] On the other hand, if skew has occurred (Yes in step S504), the process proceeds to step S508, where control unit 110 controls motor drive circuit units 120, 140 to rotate roll paper Pr forward along transport path 9 and discharge it outside image forming device 80 (S508) without performing image formation on paper Pr by image forming unit 60. Thereafter, information that skew has occurred and information requesting that roll paper Pa, Pb be reset on spool bearing pedestals 5a, 5b are displayed on the display device of image forming device 80 or the like (S509), prompting the user to reset roll paper Pa, Pb, and ending this control flow.

[0082] 14 is a flowchart of the skew correction control performed in the image forming apparatus 80 of this embodiment. Each process in the flowchart shown in FIG. 14 is performed by the control unit 307 shown in FIG.

[0083] In step S101, control unit 307 (or control unit 110 shown in Fig. 5) detects that paper rolls Pa, Pb have been set on spool bearing pedestals 5a, 5b. Control unit 307 can detect that paper rolls Pa, Pb have been placed on spool bearing pedestals 5a, 5b based on detection information from sensors 93 (see Fig. 2) provided on paper roll receiving pedestals 8a, 8b, respectively.

[0084] In step S102, in response to detection that rolls Pa, Pb have been set, control unit 307 (or control unit 110 and motor drive circuit unit 120 shown in FIG. 5) switches the roll paper rotation motor included in roll paper drive unit 130 to the ON state, and starts rotating the rolls Pa, Pb set in spool bearing stands 5a, 5b in the forward direction. As a result, roll-shaped paper Pr is pulled out from the rolls Pa, Pb and supplied to transport path 9. At this time, motor drive circuit unit 140 rotates the rollers of transport unit 160, so that the leading edge of paper Pr sent out from one of the rolls Pa, Pb is transported along transport path 9 inside the device to image forming unit 60.

[0085] In step S103, skew correction is performed. In this step, for example, a subroutine process shown in Fig. 15 is performed. Fig. 15 is a flowchart of the subroutine process of the skew correction in step S103.

[0086] In step S201 in Fig. 15, the skew amount is measured by the skew amount calculation unit 308. In this step, for example, a subroutine process shown in Fig. 16 is performed. Fig. 16 is a flowchart of the subroutine process of measuring the skew amount in steps S201 and S204.

[0087] In the subroutine process of skew amount measurement shown in Fig. 16, the carriage 66 is driven from the home position (S301), and the paper edge sensor 403 detects and records the position S1 (mm) in the Y direction at which the edge of the paper Pr moving in the main scanning direction is reached (S302). Next, the paper Pr is transported a certain length M (mm) along the transport direction T (S303), and then the paper edge sensor 403 detects and records the position S2 (mm) in the Y direction at which the edge of the paper Pr is reached again (S304). Then, using the recorded positions S1 and S2 and the information of a predetermined M, the skew amount θ of the paper Pr is calculated, for example, by the following formula (1) (S305).

[0088] Skew amount θ = arctan{(S1-S2)÷M} (1)

[0089] After the skew amount θ is calculated in step S305, the skew amount calculation unit 308 outputs information on the calculated skew amount θ to the skew correction unit 309 and the cutter angle adjustment unit 310, and the process returns to the flowchart of FIG.

[0090] 15, in step S202, the skew correction unit 309 determines whether or not skew has occurred in the paper Pr in the image forming unit 60. The skew correction unit 309 determines whether or not skew has occurred based on information about the skew amount θ calculated by the skew amount calculation unit 308 in step S201.

[0091] If no skew has occurred (No in step S202), the process returns to the main flow in FIG.

[0092] On the other hand, if skew has occurred (Yes in step S202), the process proceeds to step S203, where the skew correction unit 309 performs skew correction using the conveyance unit 160. The process content of this step is the same as the process of step S503 in FIG.

[0093] After the skew correction is performed by the transport unit 160 in step S203, the skew amount is measured again in step S204 by the skew amount calculation unit 308. In this step, the subroutine process of FIG. 16 is performed in the same manner as in step S201.

[0094] Next, in step S205, the skew correction unit 309 again determines whether or not skew has occurred in the paper Pr in the image forming unit 60. The skew correction unit 309 determines whether or not skew has occurred based on information about the skew amount θ calculated by the skew amount calculation unit 308 in step S204.

[0095] If no skew has occurred (No in step S205), it is determined that the skew has been eliminated solely by the skew correction by the transport unit 160 in step S203, and the process returns to the main flow in FIG.

[0096] On the other hand, if skew has occurred (Yes in step S205), the skew correction by the transport unit 160 in step S203 determines that skew in the paper Pr still remains. In this case, the process proceeds to step S206, where the cutter angle adjustment unit 310 adjusts the cutter angle using the skew support unit 30. In this step, for example, a subroutine process shown in Fig. 17 is performed. Fig. 17 is a flowchart of the subroutine process of the cutter angle adjustment in step S206.

[0097] In the cutter angle adjustment subroutine process shown in FIG. 17, when the angle adjustment motor 300 is driven by the skew support unit 30 (S401), the encoder 302 rotates via the shaft 301. The rotation amount sensor 303 counts the rotation of the encoder 302 (S402), i.e., the rotation amount of the encoder 302 is detected, and the cutter angle adjustment unit 310 calculates the tilt angle of the cutter unit 76 based on the rotation amount of the encoder 302. The cutter angle adjustment unit 310 continues driving the angle adjustment motor 300 and rotating the encoder 302 during a period in which the calculated tilt angle of the cutter unit 76 has not yet reached the target adjustment value, i.e., the tilt angle θp (see FIG. 9) corresponding to the skew amount θ (No in S403). On the other hand, when the tilt angle of the cutter unit 76 reaches the target adjustment value θp (Yes in S403), the angle adjustment motor 300 is stopped and fixed at the tilt angle θp at this time (S404), and the process returns to the flowchart of FIG. 15.

[0098] Returning to FIG. 15, when the cutter angle adjustment process in step S206 is completed and the cutter unit 76 is held at the inclination angle θp corresponding to the skew amount θ, the process returns to the main flow in FIG.

[0099] Returning to FIG. 14, in step S104, the cutter control unit 311 controls the operation of the cutter unit 76 so that the leading end portion of the rolled paper Pr (roll paper) on which the image is formed by the image forming unit 60 is cut and separated.

[0100] Then, in step S105, the control unit 307 (or the control unit 110 and motor drive circuit units 120, 140 shown in FIG. 5) rotates the leading edge of the remaining cut paper Pr in the reverse direction along the transport path 9 to rewind it, and moves it to a position where it can be detected by the paper end sensor 403 of the carriage 66. At this position, the motor drive circuit units 120, 140 are controlled to stop the roll paper rotation motor included in the roll paper drive unit 130. Then, in step S106, the leading edge of the rolled paper Pr stops at the print feed position and goes into standby, ending this control flow.

[0101] The effects of the image forming apparatus 80 according to this embodiment will be described. The image forming apparatus 80 according to this embodiment includes a cutter unit 76 that cuts a roll of paper Pr as a long recording medium, a skew amount calculation section 308 that calculates a skew amount θ of the paper Pr, and a skew adjustment unit 30 that adjusts the cutting direction of the cutter unit 76 with respect to the conveying direction T of the paper Pr according to the skew amount θ.

[0102] With this configuration, if skew occurs on the paper Pr during image formation on the paper Pr, the cutting direction of the cutter unit 76 can be adjusted by the skew countermeasure unit 30 according to the skew amount θ, so that the skew amount θ of the paper Pr and the paper cutting direction of the cutter unit 76 can be aligned. This makes it possible to prevent the paper Pr from being cut obliquely with respect to the width direction even if skew occurs. Therefore, unlike the conventional method described with reference to FIG. 13 (especially steps S508 and S509), it is no longer necessary to request the user to perform an operation such as re-setting the roll paper Pa, Pb on the spool bearing bases 5a, 5b when skew occurs due to a paper feed failure. As a result, the image forming device 80 of this embodiment can prevent the user's convenience from being impaired when skew occurs on the recording medium paper Pr.

[0103] Moreover, the image forming apparatus 80 of this embodiment includes a transport unit 160 that transports the paper Pr, and a skew correction unit 309 that performs skew correction using the transport unit 160 so as to reduce the skew amount θ. If skew remains in the paper Pr after the skew correction is performed by the skew correction unit 309, the skew response unit 30 adjusts the cutting direction of the cutter unit 76 according to the skew amount θ calculated by the skew amount calculation unit 308 after the skew correction is performed.

[0104] Conventionally, skew correction is performed by the conveying unit 160 as in, for example, Patent Document 1. However, if the skew correction by the conveying unit 160 cannot completely eliminate the skew, even if the image is adjusted according to the skew, the end of the paper Pr may be cut obliquely, and this may cause paper folding due to overflow when multiple papers are bundled together, or may cause jamming due to irregular shapes when the paper Pr is used as a document, resulting in a loss of convenience for the user. In response to such problems with the conventional technology, in this embodiment, even if the skew correction by the conventional conveying unit 160 cannot completely eliminate the skew when the paper Pr of the recording medium is skewed, the skew correction unit 30 can compensate for the deficiencies of the conventional skew correction method. This prevents the user's convenience from being impaired, and improves the convenience and versatility of the image forming device 80.

[0105] In the image forming apparatus 80 of this embodiment, the cutter unit 76 is formed in a shape in which the width direction of the paper Pr is the longitudinal direction. As described with reference to Figs. 6 to 9, the skew adjustment unit 30 rotates the cutter unit 76 about the central portion of the cutter unit 76 in the longitudinal direction as the cutter rotation axis 305, and adjusts the inclination angle of the cutting direction with respect to the transport direction T in accordance with the skew amount θ.

[0106] This configuration can reduce distortion in the cutting direction even when the cutter unit 76 is rotated. Also, as described with reference to Figure 10, the operating range of the skew compensation unit 30 required to adjust the inclination angle can be reduced, so the skew compensation unit 30 can be made smaller.

[0107] In the image forming apparatus 80 of the present embodiment, the cutter unit 76 is formed in a shape in which the width direction of the paper Pr is the longitudinal direction. The skew response unit 30 includes an angle adjustment motor 300, a shaft 301 installed to rotate around its axis by the rotation of the angle adjustment motor 300, a slide block 304 connected to the shaft 301, which moves in the axial direction of the shaft 301 by the rotation of the shaft 301 and is connected to an end of the cutter unit 76 in the longitudinal direction, and cutter rotation shafts 305, 305b installed to rotate the cutter unit 76 so as to tilt the cutting direction of the cutter unit 76 with respect to the conveying direction T at any position in the longitudinal direction of the cutter unit 76. The skew response unit 30 rotates the angle adjustment motor 300 to move the slide block 304 by the rotation of the shaft 301, thereby rotating the cutter unit 76 around the cutter rotation shafts 305, 305b and adjusting the cutting direction of the cutter unit 76.

[0108] This configuration makes it easy to match the amount of rotation of the angle adjustment motor 300 with the amount of rotation of the cutter unit 76 around the cutter rotation axes 305, 305b, making it possible to adjust the cutting direction of the cutter unit 76 with high precision based on the control of the angle adjustment motor 300.

[0109] The present embodiment has been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. Any design modifications made by a person skilled in the art to these specific examples are also included within the scope of the present disclosure as long as they have the features of the present disclosure. The elements of each of the above-mentioned specific examples and their arrangements, conditions, shapes, etc. are not limited to those exemplified and can be changed as appropriate. The combination of each of the elements of each of the above-mentioned specific examples can be changed as appropriate as long as no technical contradiction occurs.

[0110] In the above embodiment, the control unit 307 has the skew correction unit 309 and the cutter angle adjustment unit 310, and when skew remains in the paper Pr even after the skew correction unit 309 performs skew correction by the transport unit 160, the cutter angle adjustment unit 310 adjusts the paper cutting direction of the cutter unit 76 using the skew response unit 30. However, in the image forming apparatus 80 of the above embodiment, it is sufficient to at least adjust the paper cutting direction of the cutter unit 76 using the skew response unit 30, and the configuration may be such that the skew correction unit 309 is not provided. In this case, when skew occurs in the paper Pr, the skew correction by the transport unit 160 is not performed, and the paper cutting direction of the cutter unit 76 is directly adjusted using the skew response unit 30. [Explanation of symbols]

[0111] 80 Image forming device 30 Skew adjustment unit (adjustment section) 76 Cutter unit 305 Cutter rotating shaft (shaft) 308 Skew amount calculation section Pr Paper (recording medium) θ Skew amount [Prior art documents] [Patent documents]

[0112] [Patent Document 1] JP 2012-126527 A

Claims

1. a cutting unit for cutting the long recording medium; a skew amount calculation unit that calculates a skew amount of the recording medium; an adjustment unit that adjusts a cutting direction of the cutting unit with respect to a conveyance direction of the recording medium in accordance with the skew amount; Equipped Image forming device.

2. A conveying unit that conveys the recording medium; a skew correction unit that performs skew correction using the transport unit so as to reduce the amount of skew; Equipped with when a skew of the recording medium remains after the skew correction is performed by the skew correction unit, the adjustment unit adjusts the cutting direction in accordance with the skew amount calculated by the skew amount calculation unit after the skew correction is performed. The image forming apparatus according to claim 1 .

3. The cutting portion is formed in a shape in which the width direction of the recording medium is a longitudinal direction, the adjustment unit rotates the cutting unit about an axis of a center portion of the cutting unit in the longitudinal direction, and adjusts an inclination angle of the cutting direction with respect to the conveying direction in accordance with the skew amount.

3. The image forming apparatus according to claim 1 or 2.

4. The cutting portion is formed in a shape in which the width direction of the recording medium is a longitudinal direction, The adjustment unit is An angle adjustment motor; a shaft that is installed so as to rotate about an axis by rotation of the angle adjustment motor; a slide block connected to the shaft, moved in the axial direction of the shaft by rotation of the shaft, and connected to an end of the cutting portion in the longitudinal direction; a rotation shaft that is installed to be able to rotate the cutting unit so as to incline the cutting direction with respect to the conveying direction at an arbitrary position in the longitudinal direction of the cutting unit; having The adjustment unit rotates the angle adjustment motor to move the slide block by rotating the shaft, thereby rotating the cutting unit around the rotation axis and adjusting the cutting direction. The image forming apparatus according to claim 1 .

Images