JP2017196744A - Image formation device, and conveyance control method for recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a position of an edge of a recording medium conveyed to be appropriately controlled.SOLUTION: An image formation device comprises: a conveyance section conveying a recording medium in a first direction; a position change section changing a position of the recording medium in a second direction perpendicular to the first direction; a detector multiplying a value obtained by measuring a position of an edge in the second direction of the recording medium passing through a detection area in association with conveyance of the conveyance section by a gain and outputting the value multiplied thereby; and a control section controlling the position of the recording medium in the second direction by controlling the position change section according to output of the detector. The control section changes the gain of the detector according to a configuration of the recording medium.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a technique for conveying a recording medium.

  Conventionally, an image forming apparatus that forms an image on a recording medium while conveying the recording medium in a predetermined conveyance direction is known. In such an image forming apparatus, the recording medium meanders with conveyance, in other words, the position of the recording medium fluctuates in the width direction orthogonal to the conveyance direction, and the position where the image is formed on the recording medium shifts in the width direction. There was a case. Therefore, the image forming apparatus described in Patent Document 1 includes a detector that detects the position in the width direction of the recording medium that passes through the detection region, and determines the position in the width direction of the recording medium based on the detection result of the detector. By controlling, the meandering of the recording medium is suppressed.

JP 2014-180805 A

  By the way, such an image forming apparatus can form images on various recording media having different configurations. However, if the configuration of the recording medium is different, the fluctuation range of the position of the end of the recording medium passing through the detection area may be different, for example, due to the difference in the positional accuracy of the end of the recording medium. Therefore, since the fluctuation range of the position of the end of the recording medium is large, the output of the detector may change abruptly, and it may be difficult to appropriately control the position of the end of the recording medium.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a technique capable of appropriately controlling the position of the end of a recording medium to be conveyed.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects.

  A first aspect (printing apparatus) of the present invention includes a transport unit that transports a recording medium in a first direction, a position changing unit that changes the position of the recording medium in a second direction orthogonal to the first direction, and a transport unit Recording is performed by controlling the position changing unit according to the detector output by multiplying the gain obtained by multiplying the measured value of the position in the second direction of the recording medium passing through the detection area with conveyance. A control unit that controls the position of the medium in the second direction, and the control unit changes the gain of the detector according to the configuration of the recording medium.

  The second aspect (recording medium transport control method) of the present invention includes a step of transporting the recording medium in the first direction and a position of an end in the second direction orthogonal to the first direction of the recording medium passing through the detection area. And a step of controlling the position of the recording medium in the second direction according to the output of the detector that multiplies the measured value and outputs the gain, and the gain of the detector is changed according to the configuration of the recording medium.

  In the present invention (the first aspect and the second aspect) configured as described above, the gain of the detector is changed according to the configuration of the recording medium. Therefore, it is possible to appropriately control the position of the end of the recording medium while suppressing a steep change in the output of the detector.

  At this time, the control unit may configure the image forming apparatus so as to change the gain according to the type of the recording medium. Accordingly, it is possible to appropriately control the position of the end of the recording medium while suppressing the steep change in the output of the detector depending on the type of the recording medium.

  Further, the image forming apparatus may be configured so that the control unit changes the gain according to the width of the recording medium in the second direction. Accordingly, it is possible to appropriately control the position of the end of the recording medium while suppressing a steep change in the output of the detector due to the width of the recording medium in the second direction.

  In addition, the control unit may configure the image forming apparatus so that the gain becomes smaller as the width of the recording medium in the second direction is narrower. As a result, since the width of the recording medium is narrow, even when the position of the end of the recording medium is likely to fluctuate in the second direction with conveyance, the steep change in the output of the detector is suppressed, and the recording medium It becomes possible to appropriately control the position of the end of the.

  Further, the control unit may configure the image forming apparatus so that the gain becomes smaller as the tolerance of the width of the recording medium in the second direction is larger. As a result, since the tolerance of the width of the recording medium in the second direction is large, even if the position of the end of the recording medium is likely to fluctuate in the second direction with conveyance, the detector output changes sharply. As a result, it is possible to appropriately control the position of the edge of the recording medium.

  Note that not all of the plurality of constituent elements included in each aspect of the present invention described above are essential, and in order to solve part or all of the above-described problems or a part of the effects described in the present specification. Or, in order to achieve all of them, it is possible to change, delete, replace with other new components, or delete some of the limited contents of some components of the plurality of components as appropriate. is there. In order to solve part or all of the above-described problems or to achieve part or all of the effects described in this specification, technical features included in one embodiment of the present invention described above. A part or all of the technical features included in the other aspects of the present invention described above may be combined to form an independent form of the present invention.

FIG. 2 is a diagram schematically illustrating an example of a device configuration included in a printer to which the invention is applied. The figure which showed typically an example of the steering mechanism provided in the delivery part. FIG. 2 is a diagram showing an electrical configuration for controlling the printer shown in FIG. 1. The figure which shows the outline | summary of the electric structure which performs steering control. The figure which shows an example of the gain table which shows the relationship between a structure of a sheet | seat, and a gain. The figure which showed typically the mode of the wave of the position of the edge of the sheet | seat in the width direction. The figure which shows typically the effect of the gain setting of an edge sensor.

  FIG. 1 is a front view schematically showing an example of a device configuration provided in a printer to which the present invention is applied. As shown in FIG. 1, in the printer 1, one sheet S (web) whose both ends are wound around the feeding shaft 20 and the winding shaft 40 in a roll shape is interposed between the feeding shaft 20 and the winding shaft 40. The sheet S is stretched, and the sheet S is transported from the feeding shaft 20 to the winding shaft 40 along the transport path Pc thus stretched. The printer 1 forms an image on the sheet S conveyed along the conveyance path Pc. In the following description, of both surfaces of the sheet S, the surface on which an image is formed is referred to as the front surface, and the opposite surface is referred to as the back surface.

There are various materials for the sheet S that can be printed by the printer 1, but typical materials include “film” and “paper”. Here, “film” includes synthetic paper, PET (Polyethylene terephthalate), PP (polypropylene), and the like, and “paper” includes high-quality paper, cast paper, art paper, coated paper, and the like. And by combining these materials as appropriate, different types of sheets S can be composed. As a specific type of sheet S,
・ Single film layer: Sheet S consisting of only one film
・ Film + Film… Sheet S formed by laminating film on film
-Paper single layer: Sheet S consisting of only one layer of paper
・ Paper + paper ... Sheet S made by stacking paper on paper
・ Paper + Film ... Sheet S made by stacking films on paper
・ Film + paper ... Sheet S made by laminating paper on film
Etc.

  As shown in FIG. 1, the printer 1 schematically includes a feeding unit 2 (feeding region) that feeds the sheet S from the feeding shaft 20, and a process unit 3 that forms an image on the sheet S fed from the feeding unit 2 ( Process region) and a winding unit 4 (winding region) for winding the sheet S on which the image is formed in the process unit 3 around the winding shaft 40.

  The feeding unit 2 includes a feeding shaft 20 around which the end of the sheet S is wound, and a driven roller 21 around which the sheet S drawn from the feeding shaft 20 is wound. The feeding shaft 20 supports the end of the sheet S by winding the end thereof with the surface of the sheet S facing outward. Then, when the feeding shaft 20 rotates clockwise in FIG. 1, the sheet S wound around the feeding shaft 20 is fed to the process unit 3 via the driven roller 21. Incidentally, the sheet S is wound around the feeding shaft 20 via a core tube 22 that can be attached to and detached from the feeding shaft 20. Therefore, when the sheet S of the feeding shaft 20 is used up, it is possible to replace the sheet S of the feeding shaft 20 by attaching a new core tube 22 around which the roll-shaped sheet S is wound to the feeding shaft 20. It has become.

  The process unit 3 supports the sheet S fed from the feeding unit 2 by the rotary drum 30 and performs processing by the functional units 51, 52, 61, 62, and 63 arranged along the outer peripheral surface of the rotary drum 30. An image is formed on the sheet S as appropriate. In the process unit 3, a front drive roller 31 and a rear drive roller 32 are provided on both sides of the rotary drum 30, and the sheet S conveyed from the front drive roller 31 to the rear drive roller 32 is supported by the rotary drum 30. And receiving image formation.

  The front drive roller 31 has a plurality of minute protrusions formed by thermal spraying on the outer peripheral surface, and winds the sheet S fed from the feeding unit 2 from the back side. Then, the front drive roller 31 rotates in the clockwise direction in FIG. 1 to convey the sheet S fed from the feeding unit 2 to the downstream side of the transport path Pc. A nip roller 31 n is provided for the front drive roller 31. The nip roller 31n is in contact with the surface of the sheet S while being urged toward the front drive roller 31, and sandwiches the sheet S between the front drive roller 31 and the nip roller 31n. Thereby, the frictional force between the front drive roller 31 and the sheet S is ensured, and the sheet S can be reliably conveyed by the front drive roller 31.

  The rotary drum 30 is a cylindrical drum having a diameter of, for example, 400 [mm] that is rotatably supported by a support mechanism (not shown), and is conveyed from the front drive roller 31 to the rear drive roller 32. Wrap from the back side. The rotary drum 30 supports the sheet S from the back side while receiving and rotating in the direction opposite to the conveyance direction Ds or the conveyance direction Ds of the sheet S under the friction force with the sheet S. Incidentally, the process unit 3 is provided with driven rollers 33 and 34 for folding the sheet S on both sides of the winding part around the rotary drum 30. Among these, the driven roller 33 wraps the surface of the sheet S between the front driving roller 31 and the rotary drum 30 and folds the sheet S. On the other hand, the driven roller 34 wraps the surface of the sheet S between the rotary drum 30 and the rear drive roller 32 and folds the sheet S. In this way, by folding the sheet S on the upstream and downstream sides in the transport direction Ds with respect to the rotating drum 30, it is possible to secure a long winding portion of the sheet S around the rotating drum 30.

  The rear drive roller 32 has a plurality of minute protrusions formed by thermal spraying on the outer peripheral surface, and winds the sheet S conveyed from the rotary drum 30 via the driven roller 34 from the back surface side. Then, the rear drive roller 32 conveys the sheet S to the winding unit 4 by rotating clockwise in FIG. A nip roller 32n is provided for the rear drive roller 32. The nip roller 32 n is in contact with the surface of the sheet S while being urged toward the rear drive roller 32, and sandwiches the sheet S between the rear drive roller 32. Accordingly, a frictional force between the rear drive roller 32 and the sheet S is ensured, and the sheet S can be reliably conveyed by the rear drive roller 32.

  Thus, the sheet S conveyed from the front drive roller 31 to the rear drive roller 32 is supported on the outer peripheral surface of the rotary drum 30. In the process unit 3, in order to form a color image on the surface of the sheet S supported by the rotary drum 30, a plurality of recording heads 51 corresponding to different colors are provided. Specifically, four recording heads 51 corresponding to yellow, cyan, magenta, and black are arranged in the transport direction Ds in this color order. Each recording head 51 is opposed to the surface of the sheet S wound around the rotary drum 30 with a slight clearance, and discharges the corresponding color ink (colored ink) from the nozzles by an ink jet method. Then, each recording head 51 ejects ink onto the sheet S conveyed in the conveyance direction Ds, whereby a color image is formed on the surface of the sheet S.

  Incidentally, as the ink, UV (ultraviolet) ink (photo-curable ink) that is cured by irradiating ultraviolet rays (light) is used. Therefore, in the process unit 3, UV irradiators 61 and 62 (light irradiating units) are provided to cure the ink and fix it on the sheet S. The ink curing is performed in two stages, temporary curing and main curing. A temporary curing UV irradiator 61 is disposed between each of the plurality of recording heads 51. That is, the UV irradiator 61 irradiates weak ultraviolet rays to cure (temporarily cure) the ink to such an extent that the shape of the ink does not collapse, and does not completely cure the ink. On the other hand, a UV irradiator 62 for main curing is provided downstream of the recording heads 51 in the transport direction Ds. That is, the UV irradiator 62 completely cures (mainly cures) the ink by irradiating ultraviolet rays stronger than the UV irradiator 61.

  As described above, the UV irradiator 61 disposed between each of the plurality of recording heads 51 temporarily cures the colored ink discharged onto the sheet S from the recording head 51 on the upstream side in the transport direction Ds. Therefore, the ink ejected from the one recording head 51 onto the sheet S is temporarily cured before reaching the recording head 51 adjacent to the one recording head 51 on the downstream side in the transport direction Ds. As a result, the occurrence of color mixing such as mixing of colored inks of different colors is suppressed. In a state in which the color mixture is suppressed in this way, the plurality of recording heads 51 eject colored inks of different colors to form a color image on the sheet S. Further, a UV irradiator 62 for main curing is provided downstream of the plurality of recording heads 51 in the transport direction Ds. Therefore, the color image formed by the plurality of recording heads 51 is finally cured by the UV irradiator 62 and fixed on the sheet S.

  Furthermore, a recording head 52 is provided downstream of the UV irradiator 62 in the transport direction Ds. The recording head 52 is opposed to the surface of the sheet S wound around the rotating drum 30 with a slight clearance, and discharges transparent UV ink from the nozzles onto the surface of the sheet S by an inkjet method. That is, the transparent ink is further ejected with respect to the color image formed by the recording heads 51 for four colors. The transparent ink is ejected over the entire surface of the color image, and gives the color image a texture such as a glossy feeling or a matte feeling. Further, a UV irradiator 63 is provided on the downstream side of the recording head 52 in the transport direction Ds. The UV irradiator 63 irradiates strong ultraviolet rays to completely cure (main cure) the transparent ink ejected by the recording head 52. Thereby, the transparent ink can be fixed on the surface of the sheet S.

  As described above, in the process unit 3, ink discharge and curing are appropriately performed on the sheet S wound around the outer peripheral portion of the rotary drum 30, and a color image coated with transparent ink is formed. Then, the sheet S on which the color image is formed is conveyed to the winding unit 4 by the rear drive roller 32.

  The winding unit 4 includes a driven roller 41 that winds the sheet S from the back side between the winding shaft 40 and the rear drive roller 32 in addition to the winding shaft 40 around which the end of the sheet S is wound. The winding shaft 40 winds and supports the end of the sheet S with the surface of the sheet S facing outward. That is, when the winding shaft 40 rotates clockwise in FIG. 1, the sheet S conveyed from the rear drive roller 32 is wound around the winding shaft 40 via the driven roller 41. Incidentally, the sheet S is wound around the winding shaft 40 via a core tube 42 that can be attached to and detached from the winding shaft 40. Therefore, when the sheet S wound around the winding shaft 40 is full, the sheet S can be removed together with the core tube 42.

  Incidentally, as described above, in the configuration in which the recording heads 51 and 52 perform image formation on the sheet S conveyed to the rotary drum 30, when the sheet S conveyed in the conveyance direction Ds meanders, it is orthogonal to the conveyance direction Ds. The image forming position with respect to the sheet S is shifted in the width direction Dw. Therefore, the printer 1 includes a steering mechanism 2s (FIG. 2) in the feeding unit 2 in order to suppress the meandering of the sheet S by adjusting the position of the sheet S in the width direction Dw.

  FIG. 2 is a diagram schematically illustrating an example of a steering mechanism provided in the feeding portion. FIG. 2 shows a state in which the steering mechanism 2s is developed in the transport direction Ds. The steering mechanism 2s includes the width direction driving mechanisms A20 and A21 and the edge sensor 200 (FIG. 1) in addition to the feeding shaft 20 and the driven roller 21 described above. In FIG. 2, a detection area Re of the edge sensor 200 is shown instead of the edge sensor 200. The steering mechanism 2s performs steering control (width direction movement control) for adjusting the position of the sheet S in the width direction Dw (direction perpendicular to the paper surface of FIG. 1) perpendicular to the transport direction Ds.

  The width direction drive mechanism A20 is a drive that displaces the sheet S in the width direction Dw at a portion wound around the feed shaft 20 by displacing the feed shaft 20 in the width direction Dw (axial direction) by a driving force of a motor or an actuator. Mechanism. Further, the width direction driving mechanism A21 displaces the sheet S in the width direction Dw at the portion around the driven roller 21 by displacing the driven roller 21 in the width direction Dw (axial direction) by the driving force of the motor or actuator. This is a driving mechanism. The steering mechanism 2s cooperates with the width direction driving mechanisms A20 and A21 to adjust the position in the width direction Dw of the sheet S in the winding portion thereof, so that the steering mechanism 2s is parallel to the conveyance direction Ds. The sheet S is conveyed toward the rotary drum 30.

  On the downstream side of the driven roller 21 in the transport direction Ds (between the driven roller 21 and the front drive roller 31 shown in FIG. 1), the edge sensor 200 is disposed to face the end E of the sheet S in the width direction Dw. The edge sensor 200 has a detection region Re having a predetermined detection width in the width direction Dw, and detects the position of the end E of the sheet S in the width direction Dw in the detection region Re. Specifically, the edge sensor 200 can be configured by a distance sensor or the like that measures the distance to an object in the detection region Re. The edge sensor 200 is configured to be movable in the width direction Dw. For example, when an operator moves the edge sensor 200 in the width direction Dw, the detection region Re of the edge sensor 200 is moved in the width direction Dw. The positional relationship between the edge E of the sheet S and the detection region Re can be optimized.

  Then, as will be described later, the steering mechanism 2s performs feedback control of the width direction driving mechanisms A20 and A21 based on the result of detecting the position of the end E of the sheet S by the edge sensor 200, so that the sheet S in the width direction Dw. Is adjusted to the target position Yo. As a result, the sheet S is conveyed toward the rotary drum 30 in a state parallel to the conveyance direction Ds. Incidentally, the target position Yo is basically set so that the position Y30 of the center line of the rotary drum 30 coincides with the center line of the sheet S in the width direction Dw.

The above is the outline of the device configuration of the printer 1. Subsequently, an electrical configuration for controlling the printer 1 will be described. FIG. 3 is a block diagram showing an electrical configuration for controlling the printer shown in FIG. The printer 1 is provided with a printer control unit 100 that controls each unit of the printer 1 in accordance with a command from an external device such as a host computer. The printer control unit 100 includes a CPU (Central Processing Unit) and a RAM (Random Access).
Memory) and the like.

  The printer 1 is provided with a UI (User Interface) 7. The UI 7 includes a monitor such as a liquid crystal display and input devices such as a keyboard and a mouse. Therefore, the user can set various printing conditions such as the type of the sheet S, the size of the sheet S, and the printing quality by operating the input device of the UI 7 while confirming the monitor of the UI 7. The specific configuration of the UI 7 can be variously modified. For example, the monitor and the input device may be integrally configured by a touch panel display.

  The printer control unit 100 controls each unit of the recording head, the UV irradiator, and the sheet conveyance system based on a command from an external device or an input setting to the UI 7 by the user. Details of the control of the printer control unit 100 for each part of the apparatus are as follows.

  The printer control unit 100 controls the ink ejection timing of each recording head 51 that forms a color image according to the conveyance of the sheet S. Specifically, the control of the ink ejection timing is executed based on the output (detection value) of a drum encoder E30 that is attached to the rotating shaft of the rotating drum 30 and detects the rotational position of the rotating drum 30. That is, since the rotary drum 30 is driven to rotate as the sheet S is conveyed, the conveyance position of the sheet S can be grasped by referring to the output of the drum encoder E30 that detects the rotation position of the rotary drum 30. Therefore, the printer control unit 100 generates a pts (print timing signal) signal from the output of the drum encoder E30, and controls the ink ejection timing of each recording head 51 based on this pts signal, so that each recording head 51 has the same function. The ejected ink is landed on the target position of the conveyed sheet S to form a color image.

  Similarly, the timing at which the recording head 52 discharges the transparent ink is also controlled by the printer control unit 100 based on the output of the drum encoder E30. Thereby, it is possible to accurately eject the transparent ink to the color image formed by the plurality of recording heads 51. Further, the printer controller 100 also controls the timing of turning on / off the UV irradiators 61, 62, and 63 and the amount of irradiation light.

  Further, the printer control unit 100 manages a function of controlling the conveyance of the sheet S described in detail with reference to FIG. That is, motors are connected to the feeding shaft 20, the front drive roller 31, the rear drive roller 32, and the take-up shaft 40 among members constituting the sheet conveyance system. The printer control unit 100 controls the conveyance of the sheet S by controlling the speed and torque of each motor while rotating these motors. Details of the conveyance control of the sheet S are as follows.

  The printer control unit 100 rotates the feeding motor M <b> 20 that drives the feeding shaft 20, and supplies the sheet S from the feeding shaft 20 to the front drive roller 31. At this time, the printer control unit 100 controls the torque of the feeding motor M20 to adjust the tension (feeding tension Ta) of the sheet S from the feeding shaft 20 to the front drive roller 31. That is, a tension sensor S <b> 21 for detecting the feeding tension Ta is attached to the driven roller 21 disposed between the feeding shaft 20 and the front drive roller 31. The tension sensor S21 can be constituted by a load cell that detects a force received from the sheet S, for example. The printer control unit 100 adjusts the feeding tension Ta of the sheet S by feedback controlling the torque of the feeding motor M20 based on the detection result of the tension sensor S21.

  Further, the printer control unit 100 rotates the front drive motor M31 that drives the front drive roller 31 and the rear drive motor M32 that drives the rear drive roller 32. As a result, the sheet S fed from the feeding unit 2 passes through the process unit 3. At this time, speed control is executed for the front drive motor M31, while torque control is executed for the rear drive motor M32. That is, the printer control unit 100 adjusts the rotation speed of the front drive motor M31 to be constant based on the encoder output of the front drive motor M31. As a result, the sheet S is conveyed at a constant speed by the front drive roller 31.

  On the other hand, the printer control unit 100 controls the torque of the rear drive motor M32 to adjust the tension (process tension Tb) of the sheet S from the front drive roller 31 to the rear drive roller 32. That is, the tension sensor S34 for detecting the process tension Tb is attached to the driven roller 34 disposed between the rotary drum 30 and the rear drive roller 32. The tension sensor S34 can be configured by a load cell that detects a force received from the sheet S, for example. The printer control unit 100 adjusts the process tension Tb of the sheet S by feedback controlling the torque of the rear drive motor M32 based on the detection result of the tension sensor S34.

  Further, the printer control unit 100 rotates the winding motor M <b> 40 that drives the winding shaft 40, and winds the sheet S conveyed by the rear driving roller 32 around the winding shaft 40. At this time, the printer control unit 100 controls the torque of the winding motor M40 to adjust the tension (winding tension Tc) of the sheet S from the rear drive roller 32 to the winding shaft 40. That is, a tension sensor S41 for detecting the winding tension Tc is attached to the driven roller 41 disposed between the rear drive roller 32 and the winding shaft 40. The tension sensor S41 can be configured by a load cell that detects a force received from the sheet S, for example. The printer control unit 100 adjusts the winding tension Tc of the sheet S by feedback controlling the torque of the winding motor M40 based on the detection result of the tension sensor S41.

  Further, the printer control unit 100 has a steering control function by the steering mechanism 2s described above, and feedback-controls the width direction driving mechanisms A20 and A21 based on the detection result of the edge sensor 200. Next, this steering control will be described in detail with reference to FIG.

  FIG. 4 is a block diagram showing an outline of an electrical configuration for executing steering control. As shown in FIG. 4, the edge sensor 200 includes a light emitting element 201 such as an LED (Light Emitting Diode) and a light receiving element 202 such as a photoelectric element. A part of the light emitted from the light emitting element 201 toward the end E of the sheet S is reflected near the end E of the sheet S and then enters the light receiving element 202. The light receiving element 202 is positioned at the position of the incident light. A signal ye having a corresponding level is output. Thus, the measurement position ye is obtained as a result of measuring the position of the end E of the sheet S in the width direction Dw. The edge sensor 200 has a built-in variable gain amplifier 203 that amplifies the output of the light receiving element 202, and detection is performed by multiplying the measurement position ye of the end E of the sheet S in the width direction Dw by the gain G of the variable gain amplifier 203. The value Ye (= G × ye) is output.

  On the other hand, the printer control unit 100 includes a steering control block 110 that constitutes a part of the steering mechanism 2s, and a storage unit 120 that is configured by an HDD (Hard Disk Drive) or the like. The steering control block 110 controls the width direction driving mechanisms A20 and A21 so that the end E of the sheet S approaches the target position Yo based on the comparison between the detection value Ye of the edge sensor 200 and the target position Yo. Thus, the position of the end E of the sheet S in the width direction Dw is feedback-controlled, so that the meandering of the sheet S is suppressed.

  At this time, the steering control block 110 adjusts the gain G of the variable gain amplifier 203 of the edge sensor 200 based on the information stored in the storage unit 120. That is, the storage unit 120 stores sheet information Is indicating the configuration of the sheet S input by the user to the UI 7, a gain table Tg indicating the gain G corresponding to the configuration of the sheet S indicated by the sheet information Is, and the like. . The configuration of the sheet S is a concept including the type of the sheet S described above, the dimension of the sheet S in the width direction Dw (that is, the width W), and the like.

  FIG. 5 is a table showing an example of a gain table showing the relationship between the sheet configuration and the gain. In the table, the gain G corresponding to the type of the sheet S is shown in the vertical direction, and the gain G corresponding to the width W of the sheet S is shown in the horizontal direction. As shown in FIG. 5, regardless of the width W of the sheet S, the gain G for the type of sheet S including the film as the material has a type of sheet S that does not include the film (that is, includes only paper). It is set to be lower than the gain G for a single paper layer, paper + paper). In addition, in the range where the width W of the sheet S is equal to or larger than the predetermined width (160 [mm]), the gain G for the type of sheet S that does not include paper (that is, includes only film) is included in the material. It is set lower than the gain G for the type of sheet S. Further, the gain G for the sheet S of the type including both paper and film as the material is set lower as the width W of the sheet S is narrower. As described above, the reason why the gain G of the edge sensor 200 is changed according to the configuration of the sheet S, such as the type of the sheet S and the width W, is that the degree of the undulation at the position of the end E of the sheet S in the width direction Dw. This is to cope with differences depending on the configuration.

  FIG. 6 is a diagram schematically showing the state of corrugation at the end of the sheet in the width direction. As shown in the figure, the end E of the sheet S varies so as to wave according to the position in the transport direction Ds. As a result, the position of the edge E of the sheet S passing through the detection region Re as the sheet S is conveyed in the conveyance direction Ds vibrates in the width direction Dw with time. At this time, if the amplitude Ae at which the position of the edge E of the sheet S vibrates is large, the detection value Ye of the edge sensor 200 changes sharply in a short time. However, performing the steering control by the steering control block 110 based on such a steep change makes the position of the seat S in the width direction Dw unstable, making it difficult to perform the steering control appropriately. There was a case.

  On the other hand, due to the manufacturing method and the like, the type of sheet S including a film as a raw material tends to have a larger tolerance (error) of its width W than the type of sheet S including a paper as a raw material. As a result, the position of the end E tends to vibrate with a large amplitude Ae. Therefore, the gain G of the edge sensor 200 is adjusted depending on whether or not the sheet S includes a film as a material, in other words, whether or not the tolerance of the width W of the sheet S is large. Specifically, the gain G of the edge sensor 200 is set smaller as the tolerance of the width W of the sheet S is larger.

  Further, when the width W of the sheet S is narrow, the rigidity of the sheet S is lowered, and therefore the position of the sheet S in the width direction Dw tends to become unstable. As a result, instability of the position of the end E of the sheet S due to the narrowness of the width W of the sheet S is added to the vibration of the position of the end E of the sheet S due to the tolerance of the width W of the sheet S. The position of the end E of the sheet S tends to be more vibrational. Therefore, the smaller the width W of the sheet S, the smaller the gain G of the edge sensor 200 is set.

  And it becomes possible to perform steering control appropriately by setting the gain of the edge sensor 200 according to the gain table Tg shown in FIG. FIG. 7 is a diagram schematically showing the effect of gain setting of the edge sensor. The horizontal axis of the figure represents the time t, and the vertical axis of the figure represents the detected value Ye of the edge E of the sheet S in the width direction Dw. The broken line in the figure shows the case where the edge sensor 200 having a large gain G detects the edge E of the sheet S containing the film, and the solid curve in the figure shows the film made of the material by the edge sensor 200 having a small gain G. The case where the edge E of the sheet S included in is detected is shown. As shown by the broken curve, when the gain G of the edge sensor 200 is large, the vibration amplitude Ae1 of the detection value Ye of the end E of the sheet S is large, and the change of the detection value Ye is steep. Therefore, it may be difficult to perform steering control appropriately. On the other hand, as shown by the solid curve, when the gain G of the edge sensor 200 is small, the vibration amplitude Ae2 of the detection value Ye of the end E of the sheet S is suppressed to be small, and the change of the detection value Ye becomes gentle. . Therefore, it is possible to appropriately perform steering control.

  As described above, in the present embodiment, the gain G of the edge sensor 200 is changed according to the configuration of the sheet S. Therefore, it is possible to appropriately control the position of the edge E of the sheet S while suppressing a steep change in the output Ye of the edge sensor 200.

  Further, the steering control block 110 changes the gain G according to the type of the seat S. Accordingly, it is possible to appropriately control the position of the edge E of the sheet S while suppressing a steep change in the output Ye of the edge sensor 200 depending on the type of the sheet S.

  Further, the steering control block 110 changes the gain G according to the width W of the seat S. Accordingly, it is possible to appropriately control the position of the edge E of the sheet S while suppressing the output change of the edge sensor 200 from being steep due to the width W of the sheet S.

  Further, the steering control block 110 decreases the gain G as the width W of the seat S is reduced. As a result, since the width W of the sheet S is narrow, even if the position of the end E of the sheet S is likely to fluctuate in the width direction Dw along with the conveyance, a sharp change in the output Ye of the edge sensor 200 is suppressed. Thus, the position of the edge E of the sheet S can be appropriately controlled.

  In addition, the steering control block 110 decreases the gain G as the tolerance of the width W of the seat S increases. Accordingly, since the tolerance of the width W of the sheet S is large, even when the position of the end E of the sheet S is likely to fluctuate in the width direction Dw with conveyance, the output Ye of the edge sensor 200 is abruptly changed. Thus, the position of the edge E of the sheet S can be controlled appropriately.

  As described above, in the above embodiment, the printer 1 corresponds to an example of the “image forming apparatus” of the present invention, and the feeding shaft 20, the front driving roller 31, the rear driving roller 32, and the winding shaft 40 cooperate. The width direction drive mechanisms A20 and A21 cooperate to function as an example of the “position changing unit” of the present invention, and the edge sensor 200 functions as an example of the “detector” of the present invention. The detection area Re corresponds to an example of the “detection area” of the present invention, the steering control block 110 corresponds to an example of the “control unit” of the present invention, and the sheet S corresponds to the “recording medium” of the present invention. The conveyance direction Ds corresponds to an example of the “first direction” of the present invention, and the width direction Dw corresponds to an example of the “second direction” of the present invention.

  The present invention is not limited to the above-described embodiment, and various modifications can be made to the above-described one without departing from the spirit of the present invention. Therefore, for example, the specific numerical value of the edge sensor 200 gain G for the configuration of the sheet S is not limited to the example shown in FIG. 5 and can be changed as appropriate.

  Moreover, in the said embodiment, on the assumption that the tolerance of the width W of the sheet S which contains a film as a raw material is large, and the tolerance of the width W of the sheet S which contains a paper as a raw material is small, according to the kind of the sheet S. The gain G of the edge sensor 200 was set. However, for example, the gain G of the edge sensor 200 may be set in accordance with the value of the width W described in the specification of the sheet S according to the value input by the user to the UI 7. In such a configuration, even if the above assumption is not satisfied, it is possible to appropriately cope with it.

  Further, the specific configuration of the steering mechanism 2s is not limited to the above. In short, any mechanism that can change and adjust the position of the end E of the sheet S in the width direction Dw can function as the steering mechanism 2s.

  Further, the position or number of the edge sensors 200 can be changed as appropriate.

  In the above-described embodiment, the position control of the sheet S is performed so that the center line of the sheet S is aligned with the position X30 of the center line of the rotary drum 30. However, it is not always necessary to execute the position control of the sheet S so as to align them.

  In the above embodiment, the sheet S is supported by the cylindrical rotating drum 30. However, the shape of the member that supports the sheet S is not limited to this. For example, the sheet S may be supported by a flat surface.

DESCRIPTION OF SYMBOLS 1 ... Printer, 20 ... Feeding shaft, 31 ... Front drive roller, 32 ... Rear drive roller, 40 ... Winding shaft, A20, A21 ... Width direction drive mechanism, 200 ... Edge sensor, 201 ... Light emitting element, 202 ... Light receiving element , 203 ... variable gain amplifier, Re ... detection area, ye ... measurement position, Ye ... detection value, 110 ... printer control unit, 110 ... steering control block, 120 ... storage unit, Is ... sheet information, Tg ... gain table, S ... Sheet, Ds ... Conveying direction, Dw ... Width direction

Claims (6)

A transport unit for transporting the recording medium in the first direction;
A position changing unit that changes the position of the recording medium in a second direction orthogonal to the first direction;
A detector that multiplies and outputs a value obtained by measuring the position of the end in the second direction of the recording medium that passes through a detection area in accordance with conveyance of the conveyance unit;
A control unit that controls the position of the recording medium in the second direction by controlling the position changing unit according to the output of the detector;
The control unit is an image forming apparatus that changes the gain of the detector according to a configuration of the recording medium.   The image forming apparatus according to claim 1, wherein the control unit changes the gain according to a type of the recording medium.   The image forming apparatus according to claim 1, wherein the control unit changes the gain according to a width of the recording medium in the second direction.   The image forming apparatus according to claim 3, wherein the control unit decreases the gain as the width of the recording medium in the second direction is narrower.   5. The image forming apparatus according to claim 1, wherein the control unit decreases the gain as the tolerance of the width of the recording medium in the second direction increases. 6. Conveying the recording medium in the first direction;
In the second direction of the recording medium according to the output of the detector that outputs a value obtained by multiplying the measured value of the position of the end in the second direction orthogonal to the first direction of the recording medium passing through the detection area. And a step of controlling the position of
A recording medium conveyance control method for changing the gain of the detector according to the configuration of the recording medium.

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