JP5884499B2 - Conveying apparatus, conveying method, and image recording apparatus - Google Patents

Description

  The present invention relates to a conveyance technique for conveying a recording medium, and in particular, adjusts the tension of a recording medium by controlling the torque of a rotating shaft that rotates in accordance with the conveyance speed of the recording medium while the recording medium is wound in a roll shape. Related to technology.

  Patent Document 1 describes an apparatus that conveys a sheet in a predetermined direction by rotating the rotating shaft in a state where both ends of the sheet are wound around a rotating shaft (unwinding shaft, winding shaft) in a roll shape. . In addition, this apparatus is configured to adjust the torque of the rotating shaft in order to adjust the tension of the sheet. However, the tension of the sheet depends not only on the torque of the rotating shaft but also on the roll diameter of the sheet wound around the rotating shaft. Therefore, in order to give an appropriate tension to the sheet, it is necessary to rotate the rotating shaft with a torque corresponding to the roll diameter. Therefore, in Patent Document 1, the roll diameter is obtained from the sheet conveyance speed and the rotation speed of the rotation shaft using a relationship that the sheet conveyance speed is proportional to the product of the rotation speed and the roll diameter of the rotation shaft. An appropriate tension is applied to the sheet by adjusting the torque of the rotary shaft based on the roll diameter.

JP-A-4-94357

  By the way, as an image recording apparatus that executes an image recording process for recording an image on a recording medium, there is an apparatus that performs an image recording process while conveying a recording medium (sheet) in a predetermined direction as in Patent Document 1. Therefore, it is conceivable to apply the above technique to such an image recording apparatus to adjust the tension of the recording medium. However, the above technique obtains the roll diameter of the recording medium necessary for adjusting the tension of the recording medium from the number of rotations of the rotating shaft. Therefore, in order to start the image recording process, in order to obtain the roll diameter necessary for adjusting the tension of the recording medium, it is necessary to first rotate the rotating shaft and detect the number of rotations. As a result, the recording medium is also conveyed. Then, since the recording medium is transported before the image recording process is performed in this manner, there is a possibility that a portion of the recording medium where an image is not recorded is generated, and the recording medium is largely wasted.

  The present invention has been made in view of the above problems, and provides a technique for detecting a roll diameter of a recording medium wound around a rotating shaft while suppressing generation of waste of the recording medium before the start of image recording processing. Objective.

  In order to achieve the above object, a transport apparatus according to the present invention is a transport apparatus that transports a recording medium in a first direction at a recording speed for image recording processing in which an image is recorded on the recording medium. A rotating shaft that rotates according to the conveyance speed of the recording medium while being wound in a roll shape, a rotation number detection unit that detects the rotation number of the rotation shaft, a speed detection unit that detects the conveyance speed of the recording medium, and the rotation number The roll diameter of the recording medium wound around the rotation shaft is calculated from the rotation speed of the rotation axis detected by the detection unit and the conveyance speed of the recording medium detected by the speed detection unit, and torque corresponding to the roll diameter is calculated. A control unit that adjusts the tension of the recording medium by rotating the rotation shaft at the control unit, and the control unit adjusts the roll diameter while conveying the recording medium at a speed whose velocity component in the first direction is smaller than the recording speed. Calculate roll diameter After running mode, and executes the recording transport mode for conveying the adjusted while recording medium tension of the recording medium based on the roll diameter at a recording speed in a first direction.

  In order to achieve the above object, a transport method according to the present invention is a transport method for transporting a recording medium in a first direction at a recording speed for image recording processing in which an image is recorded on the recording medium. The roll diameter of the recording medium wound around the rotating shaft is calculated from the rotational speed of the rotating shaft that rotates according to the conveying speed of the recording medium and the conveying speed of the recording medium in a state of being wound in a roll shape, and according to the roll diameter Roll diameter calculation mode for calculating the roll diameter while transporting the recording medium at a speed smaller than the recording speed in order to adjust the tension of the recording medium by rotating the rotating shaft with the torque Then, a recording transport mode is performed in which the recording medium is transported in the first direction at a recording speed while adjusting the tension of the recording medium based on the roll diameter.

  In order to achieve the above object, an image recording apparatus according to the present invention includes an conveyance mechanism that conveys a recording medium in a first direction at a recording speed for image recording processing in which an image is recorded on the recording medium. In the recording apparatus, the transport mechanism includes a rotating shaft that rotates in accordance with the transport speed of the recording medium in a state in which the recording medium is wound in a roll shape, a rotational speed detection unit that detects the rotational speed of the rotational shaft, and a transport of the recording medium A roll diameter of the recording medium wound around the rotation shaft from the speed detection unit for detecting the speed, the rotation speed of the rotation shaft detected by the rotation speed detection unit, and the conveyance speed of the recording medium detected by the speed detection unit And a control unit that adjusts the tension of the recording medium by rotating the rotating shaft with a torque corresponding to the roll diameter, and the control unit has a velocity component in the first direction smaller than the recording velocity. Carry recording media at speed Then, after executing the roll diameter calculation mode for calculating the roll diameter, executing the recording transport mode for transporting the recording medium in the first direction at the recording speed while adjusting the tension of the recording medium based on the roll diameter. It is characterized by.

  In the invention thus configured (conveying device, conveying method and image recording device), the roll diameter of the recording medium wound around the rotating shaft is calculated from the rotational speed of the rotating shaft and the conveying speed of the recording medium, The tension of the recording medium is adjusted by rotating the rotating shaft with a torque corresponding to the roll diameter. That is, when determining the roll diameter, it is necessary to detect the rotational speed by rotating the rotary shaft as described above, and at this time, the recording medium is also conveyed along with the rotation of the rotary shaft. When the recording medium is transported before the image recording process is performed, there is a possibility that a portion of the recording medium where an image is not recorded is generated, and the recording medium is largely wasted.

  However, in the present invention, the speed component in the first direction is smaller than the recording speed before the recording transport mode in which the recording medium is transported in the first direction at the recording speed to perform image recording processing on the recording medium. A roll diameter calculation mode is executed in which the roll diameter is calculated while conveying the recording medium at a speed. As described above, in the roll diameter calculation mode for calculating the roll diameter, the speed component in the first direction of the recording medium is suppressed to a speed smaller than the recording speed. Therefore, the first recording medium in the roll diameter calculation mode is used. The conveyance distance in the direction can be suppressed. In other words, the distance conveyed in the first direction when no image is recorded on the recording medium can be reduced, and as a result, the rotation of the recording medium can be suppressed while suppressing the occurrence of waste of the recording medium before the start of the image recording process. It becomes possible to detect the roll diameter of the recording medium wound around the shaft.

  Here, the control unit can transport the recording medium in the first direction at a speed smaller than the recording speed in the roll diameter calculation mode. In this case, since the recording medium conveyance direction is the same in the recording conveyance mode and the roll diameter calculation mode, the transition from the roll diameter calculation mode to the recording conveyance mode is performed quickly. As a result, the image recording process can be started quickly.

  At this time, the control unit can calculate the roll diameter in a state where the recording medium is transported in the first direction at a constant speed smaller than the recording speed. Since the output value from the speed detector is stable when the recording medium conveyance speed is constant, the roll diameter calculation accuracy is improved, and as a result, the tension of the recording medium can be accurately controlled.

  Alternatively, the control unit can calculate the roll diameter in a state where the recording medium is accelerated in the first direction toward the recording speed. If the roll diameter is calculated while the recording medium is accelerated in the first direction toward the recording speed, the recording speed can be reached quickly after the roll diameter is calculated. That is, the transition from the roll diameter calculation mode to the recording transport mode is performed more quickly, and the image recording process can be started more quickly.

  On the other hand, the control unit can transport the recording medium in the second direction opposite to the first direction in the roll diameter calculation mode. As described above, in the roll diameter calculation mode, the recording medium is transported in the second direction opposite to the first direction that is the transport direction in the recording transport mode, so that the recording medium is changed to the recording transport mode until the recording medium is shifted to the recording transport mode. The distance conveyed in one direction can be reduced more positively. Therefore, it is possible to more effectively suppress the waste of the recording medium.

  Here, at the time of executing the roll diameter calculation mode, when the end portion on the second direction side of the recorded area where the image recording process has already been performed exists on the first direction side with respect to the recording section that performs the image recording process In the roll diameter calculation mode, the control unit preferably transports the recording medium in the second direction so that the end of the recorded area is positioned on the second direction side of the recording unit. As described above, when the recording medium is transported in the second direction so that the end portion on the second direction side of the recorded area in the roll detection mode is positioned on the second direction side from the recording portion, recording is performed in the subsequent recording transport mode. The image recording process can be resumed from the adjacent area on the second direction side of the completed area, and waste of the recording medium can be more reliably suppressed. In addition, the roll diameter can be calculated when the recording medium is transported in the second direction so that the end of the recorded area in the second direction is positioned on the second direction side of the recording unit. It is reasonable to eliminate the need to transport the recording medium only for the calculation of.

  In addition, the steering unit further includes a steering unit that adjusts the position of the recording medium in the width direction while the recording medium is being conveyed in the first direction, and the control unit conveys the recording medium in the second direction in the roll diameter calculation mode Is preferably equal to or longer than the distance by which the recording medium is conveyed in the first direction until the position adjustment by the steering unit is completed after the recording medium is conveyed in the second direction. In the case where a steering unit that adjusts the position of the recording medium in the width direction is provided, in order for the steering unit to complete the position adjustment of the recording medium, the recording medium needs to be conveyed by a predetermined distance in the first direction. . Therefore, if the distance that the recording medium is conveyed in the second direction in the roll diameter calculation mode as in this configuration is set to be equal to or greater than the predetermined distance that the recording medium is conveyed in the first direction before the position adjustment is completed, Even if the recording medium is transported in the first direction for position adjustment by the steering unit, the transport distance is offset with the transport distance in the second direction in the roll diameter calculation mode. That is, it is possible to prevent the recording medium from being wasted when the recording medium is moved in the first direction for position adjustment by the steering unit.

  Furthermore, the control unit can calculate the roll diameter while the recording medium is being conveyed in the second direction at a constant speed. Since the output value from the speed detector is stable when the recording medium conveyance speed is constant, the roll diameter calculation accuracy is improved, and as a result, the tension of the recording medium can be accurately controlled.

  Further, it is preferable that the control unit calculates a torque to be applied to the rotation shaft using the outer diameter of the rotation shaft as the roll diameter until the roll diameter can be calculated. The torque applied to the rotating shaft during torque control is determined according to the product of the target tension value of the recording medium and the roll diameter. However, until the roll diameter can be calculated, that is, when the roll diameter is unknown, if torque control is performed with a roll diameter that is larger than the actual roll diameter, an excessively large torque is applied to the rotating shaft. As a result, an excessive tension acts on the recording medium, and the recording medium may be broken. Here, the roll diameter becomes smaller as the sheet is fed out from the rotating shaft, and when all the sheets are fed out, the roll diameter becomes equal to the outer diameter of the rotating shaft, which is the minimum value of the roll diameter. Therefore, until the roll diameter can be calculated, if the torque to be applied to the rotation shaft is calculated using the outer diameter of the rotation shaft, which is the minimum value of the roll diameter, as the roll diameter, a torque larger than the actual roll diameter can be obtained according to the roll diameter. Therefore, excessive torque is not applied to the rotating shaft, and the recording medium can be prevented from breaking.

FIG. 3 is a diagram schematically illustrating an example of a device configuration included in a printer to which the invention can be applied. FIG. 2 is a diagram schematically showing an electrical configuration for controlling the printer shown in FIG. 1. The chart which shows the calculation timing of the roll diameter in 1st Embodiment. The flowchart which shows the operation | movement performed by 1st Embodiment. The figure which shows the relationship between the roll diameter of a sheet | seat, and the outer diameter of a core pipe. The chart which shows the calculation timing of the roll diameter in 2nd Embodiment. The flowchart which shows the operation | movement performed by 2nd Embodiment. The chart which shows the calculation timing of the roll diameter in 3rd Embodiment. The flowchart which shows the operation | movement performed by 3rd Embodiment. The chart which shows the calculation timing of the roll diameter in 4th Embodiment. The flowchart which shows the operation | movement performed in 4th Embodiment. FIG. 10 is a diagram illustrating a conveyance distance in the reverse direction of a sheet according to a fourth embodiment.

[First Embodiment]
FIG. 1 is a front view schematically showing an example of a device configuration included in a printer to which the present invention can be 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 conveyed from the feeding shaft 20 to the winding shaft 40 along the path Pc thus stretched. In the printer 1, an image is recorded on the sheet S conveyed along this path (conveyance path Pc). The type of the sheet S is roughly classified into a paper type and a film type. Specific examples include high-quality paper, cast paper, art paper, coated paper, and the like for paper, and synthetic paper, PET (Polyethylene terephthalate), PP (polypropylene), and the like for film. Schematically, in the printer 1, the feeding unit 2 that feeds the sheet S from the feeding shaft 20, the process unit 3 that records an image on the sheet S that is fed from the feeding unit 2, and an image recorded by the process unit 3. A winding unit 4 for winding the sheet S around the winding shaft 40 is provided. In the following description, of both surfaces of the sheet S, the surface on which an image is recorded is referred to as the front surface, and the opposite surface is referred to as the back surface.

  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 (not shown) that is detachable from the feeding shaft 20. Therefore, when the sheet S of the feeding shaft 20 is used up, a new core tube around which the roll-shaped sheet S is wound can be mounted on the feeding shaft 20 and the sheet S of the feeding shaft 20 can be replaced. It has become.

  The process unit 3 supports the sheet S fed from the feeding unit 2 by the platen drum 30 and performs processing by the functional units 51, 52, 61, 62, and 63 arranged along the outer peripheral surface of the platen drum 30. An image is recorded 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 platen drum 30, and the sheet S conveyed from the front drive roller 31 to the rear drive roller 32 is supported by the platen drum 30. And receive an image record.

  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. 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 conveyance path. A nip roller 31n is provided for the front drive roller 31. The nip roller 31 n 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. 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 platen drum 30 is a cylindrical drum that is rotatably supported by a support mechanism (not shown), and winds the sheet S conveyed from the front drive roller 31 to the rear drive roller 32 from the back side. The platen drum 30 supports the sheet S from the back side while receiving the frictional force between the plate S and rotating in the conveyance direction Ds of 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 platen drum 30. Among these, the driven roller 33 wraps the surface of the sheet S between the front driving roller 31 and the platen drum 30 and folds the sheet S. On the other hand, the driven roller 34 wraps the surface of the sheet S between the platen drum 30 and the rear drive roller 32 and folds the sheet S. Thus, by folding the sheet S on the upstream and downstream sides in the transport direction Ds with respect to the platen drum 30, a long winding portion of the sheet S around the platen drum 30 can be secured.

  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 platen 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 platen drum 30. In the process unit 3, a plurality of recording heads 51 corresponding to different colors are provided to record a color image on the surface of the sheet S supported by the platen drum 30. 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 platen drum 30 with a slight clearance, and ejects ink of a corresponding color 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 lamps 61 and 62 (light irradiation units) are provided in order 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 lamp 61 is disposed between each of the plurality of recording heads 51. That is, the UV lamp 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 lamp 62 for main curing is provided on the downstream side in the transport direction Ds with respect to the plurality of recording heads 51. That is, the UV lamp 62 irradiates ultraviolet rays stronger than the UV lamp 61 to completely cure (main cure) the ink. By executing the temporary curing and the main curing in this manner, the color image formed by the plurality of recording heads 51 can be fixed on the surface of the sheet S.

  Further, a recording head 52 is provided downstream of the UV lamp 62 in the transport direction Ds. The recording head 52 is opposed to the surface of the sheet S wound around the platen drum 30 with a slight clearance, and discharges transparent UV ink onto the surface of the sheet S by an ink jet method. That is, the transparent ink is further ejected with respect to the color image formed by the recording heads 51 for four colors. Further, a UV lamp 63 is provided on the downstream side of the recording head 52 in the transport direction Ds. The UV lamp 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 periphery of the platen drum 30, and a color image coated with the 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 (not shown) that is detachable from the winding shaft 40. Therefore, when the sheet S wound around the winding shaft 40 becomes full, it is possible to remove the sheet S together with the core tube.

  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. 2 is a block diagram schematically showing an electrical configuration for controlling the printer shown in FIG. The operation of the printer 1 described above is controlled by the host computer 10 shown in FIG. In the host computer 10, a host control unit 100 that supervises control operations is configured by a CPU (Central Processing Unit) and a memory. The host computer 10 is provided with a driver 120, and the driver 120 reads the program 124 from the medium 122. Various media such as a CD (Compact Disk), a DVD (Digital Versatile Disk), and a USB (Universal Serial Bus) memory can be used as the medium 122. Then, the host control unit 100 controls each unit of the host computer 10 and controls the operation of the printer 1 based on the program 124 read from the medium 122.

  Further, the host computer 10 is provided with a monitor 130 constituted by a liquid crystal display or the like and an operation unit 140 constituted by a keyboard, a mouse or the like as an interface with an operator. In addition to the image to be printed, a menu screen is displayed on the monitor 130. Accordingly, the operator operates the operation unit 140 while confirming the monitor 130, thereby opening the print setting screen from the menu screen and setting various print conditions such as the type of print medium, the size of the print medium, and the print quality. Can be set. The specific configuration of the interface with the worker can be variously modified. For example, a touch panel display may be used as the monitor 130, and the operation unit 140 may be configured with the touch panel of the monitor 130.

  On the other hand, the printer 1 is provided with a printer control unit 200 that controls each unit of the printer 1 in accordance with a command from the host computer 10. Each unit of the recording head, the UV lamp, and the sheet conveyance system is controlled by the printer control unit 200. Details of the control of the printer control unit 200 for each part of the apparatus are as follows.

  The printer control unit 200 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 rotation shaft of the platen drum 30 and detects the rotation position of the platen drum 30. That is, since the platen drum 30 is driven and rotated 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 platen drum 30. Therefore, the printer control unit 200 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 200 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 200 also controls the timing of turning on / off the UV lamps 61, 62, and 63 and the amount of irradiation light.

  Further, the printer control unit 200 controls 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 200 controls the conveyance of the sheet S by controlling the speed and torque of each motor while rotating these motors. The feed shaft 20 and the take-up shaft 40 are provided with a feed shaft encoder E20 and a take-up shaft encoder E40 that detect the respective rotation speeds. Details of the conveyance control of the sheet S are as follows.

  The printer control unit 200 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 200 controls the torque of the feeding motor M20 to adjust the tension of the sheet S from the feeding shaft 20 to the front drive roller 31 (feeding tension Ta). That is, a tension sensor S21 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, for example, a load cell that detects a force received from the sheet S. The printer control unit 200 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.

  At this time, the printer control unit 200 feeds the sheet S while adjusting the position of the sheet S supplied from the feeding shaft 20 to the front drive roller 31 in the width direction (direction orthogonal to the paper surface of FIG. 1). That is, the printer 1 is provided with the steering unit 7 that displaces the feeding shaft 20 and the driven roller 21 in the axial direction (in other words, the width direction of the sheet S). Further, an edge sensor Se that detects an end of the sheet S in the width direction is disposed between the driven roller 21 and the front driving roller 31. The edge sensor Se can be constituted by a distance sensor such as an ultrasonic sensor. The printer control unit 200 adjusts the position of the sheet S in the width direction by performing feedback control of the steering unit 7 based on the detection result of the edge sensor Se. As a result, the position of the sheet S in the width direction is optimized, and conveyance failure such as meandering of the sheet S is suppressed.

  Further, the printer control unit 200 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 200 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 200 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 platen drum 30 and the rear drive roller 32. The tension sensor S34 can be constituted by a load cell that detects a force received from the sheet S, for example. The printer controller 200 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.

  In addition, the printer control unit 200 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 200 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, the 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 constituted by a load cell that detects a force received from the sheet S, for example. The printer control unit 200 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.

  The outline of the electrical configuration for controlling the printer 1 has been described above. In the printer 1 configured as described above, the feeding tension Ta of the sheet S is adjusted by controlling the torque of the feeding motor M20 as described above. Here, the torque to be applied to the feeding motor M20 is determined according to the target value of the feeding tension Ta and the roll diameter of the sheet S wound around the feeding shaft 20. Therefore, in order to obtain the torque to be applied to the feeding motor M20 in order to adjust the feeding tension Ta to the target value, it is necessary to calculate the roll diameter of the sheet S. In the following description, a case where the roll diameter of the sheet S on the feeding shaft 20 is calculated as described above is taken as an example.

  A first embodiment of the present invention will be described based on FIG. 3 and FIG. FIG. 3 is a chart showing the calculation timing of the roll diameter in the first embodiment, and FIG. 4 is a flowchart showing the operation executed in the first embodiment. In the first embodiment, after the time t3 after the roll diameter calculation mode is executed in which the roll diameter is calculated while the sheet S is conveyed in the forward direction at a speed smaller than the recording speed Vp at the times t0 to t3. A recording conveyance mode is executed in which the sheet S is conveyed in the forward direction at the recording speed Vp to perform image recording processing. Here, the forward direction is a direction in which the sheet S is conveyed during the image recording process. In the first embodiment, the recording speed Vp is a constant speed. As described above, in the roll diameter calculation mode executed before the recording conveyance mode, the sheet S is conveyed in the forward direction at a speed lower than the recording speed Vp, so that the sheet before the image recording process is started. The transport distance in the forward direction of S can be suppressed, and waste of the recording medium can be suppressed.

  During the time t1 to t2 in the roll diameter calculation mode, the sheet S is conveyed at a constant speed V1. During this constant speed conveyance, the printer control unit 200 is based on output values from the drum encoder E30 and the feeding axis encoder E20. The roll diameter of the sheet S on the feeding shaft 20 is calculated. When the conveyance speed of the sheet S is constant, the output value from the drum encoder E30 is stable, so that the calculation accuracy of the roll diameter of the sheet S on the feeding shaft 20 is improved, and as a result, the tension Ta of the sheet S is accurately determined. It becomes possible to control well.

  Based on FIG. 4, operations performed by the printer control unit 200 will be described. When a command signal for starting image recording processing is sent to the printer control unit 200 via the host control unit 100, the printer control unit 200 sets the outer diameter of the core tube as the roll diameter of the sheet S on the feeding shaft 20. (Step S101). Here, FIG. 5 is a diagram showing the relationship between the roll diameter of the sheet and the outer diameter of the core tube. As apparent from FIG. 5, the roll diameter ds of the sheet S wound around the feeding shaft 20 via the core tube C gradually decreases as the sheet S is fed from the feeding shaft 20, and the sheet S disappears. The roll diameter ds becomes equal to the outer diameter dc of the core tube C. In other words, the minimum value of the roll diameter ds of the sheet S is the outer diameter dc of the core tube C.

  As described above, the torque applied to the feeding motor M20 connected to the feeding shaft 20 is determined according to the product of the target value of the tension Ta of the sheet S and the roll diameter ds. That is, as the roll diameter ds is larger, the feeding motor M20 is rotated with a larger torque. Therefore, until the roll diameter ds can be calculated, that is, when the roll diameter ds is unknown, if the torque control is performed with a larger value than the actual roll diameter ds as the roll diameter, the feeding motor with a torque larger than necessary is performed. M20 is rotated. As a result, an excessive tension acts on the sheet S, and the sheet S may be broken. Therefore, before starting the conveyance of the sheet S as in step S101, an excessive torque is applied to the feeding motor M20 by setting the roll diameter to the outer diameter dc of the core tube C, which is the minimum value of the roll diameter ds. Thus, the sheet S can be prevented from breaking. Since the outer diameter dc of the core tube C may change depending on the type of the sheet S and the like, it is preferable that the user can set the outer diameter dc of the core tube C via the operation unit 140, for example. It is.

  Next, the printer control unit 200 accelerates the sheet S in the forward direction (step S102). When the conveyance speed of the sheet S reaches the speed V1 (step S103, YES), the acceleration of the sheet S is stopped and the constant speed conveyance is performed (step S104). When the printer control unit 200 calculates the roll diameter of the sheet S on the feeding shaft 20 based on the output values from the drum encoder E30 and the feeding shaft encoder E20 during the constant speed conveyance of the sheet S (YES in step S105), again. The sheet S is accelerated in the forward direction (step S106). When the conveyance speed of the sheet S reaches the recording conveyance speed Vp (> V1) (step S107, YES), the acceleration of the sheet S is stopped and the constant speed conveyance is performed again (step S108). Then, the image recording process is performed with the sheet S being conveyed at a constant speed at the recording conveyance speed Vp (step S109).

  Here, after the roll diameter is calculated in step S105, the feeding tension Ta of the sheet S is controlled by rotating the feeding motor M20 with a torque corresponding to the roll diameter. Once the roll diameter is calculated, the printer control unit 200 calculates the roll diameter of the sheet S on the feeding shaft 20 based on the output values from the drum encoder E30 and the feeding shaft encoder E20 at an appropriate timing. The image recording process is executed while appropriately updating the roll diameter used for torque control of the motor M20.

[Second Embodiment]
A second embodiment of the present invention will be described based on FIG. 6 and FIG. FIG. 6 is a chart showing the calculation timing of the roll diameter in the second embodiment, and FIG. 7 is a flowchart showing the operation executed in the second embodiment. The second embodiment differs from the first embodiment in the conveyance state of the sheet S in the roll diameter calculation mode, but other basic apparatus configurations and operations are the same as those in the first embodiment. Therefore, description of portions common to the first embodiment is omitted. In the second embodiment, it is needless to say that the same effects as those of the first embodiment can be obtained by providing the same configuration as that of the first embodiment.

  In the second embodiment, as shown in FIG. 6, the roll diameter of the sheet S on the feeding shaft 20 is calculated in a state where the forward conveyance speed of the sheet S is accelerated toward the recording speed Vp. . When the roll diameter is calculated in a state where the conveyance speed of the sheet S is accelerated toward the recording speed Vp as described above, the conveyance speed of the sheet S can quickly reach the recording speed Vp after the roll diameter is calculated. Therefore, the image recording process can be started more quickly. In addition, since it is not necessary to perform constant speed control of the sheet S in the roll diameter calculation mode, speed control in the roll diameter calculation mode is facilitated.

  Based on FIG. 7, the operation performed by the printer control unit 200 will be described. When a command signal for starting image recording processing is sent to the printer control unit 200 via the host control unit 100, the printer control unit 200 sets the outer diameter of the core tube as the roll diameter of the sheet S on the feeding shaft 20. (Step S201). Next, the printer control unit 200 accelerates the sheet S in the forward direction (step S202), calculates the roll diameter while accelerating the sheet S (step S203, YES), and continues acceleration in the forward direction as it is. To do. When the conveyance speed of the sheet S reaches the recording speed Vp (step S204, YES), the acceleration of the sheet S is stopped and the constant speed conveyance is performed at the recording speed Vp (step S205). Then, image recording is performed in a state where the sheet S is conveyed at a constant speed at the recording speed Vp (step S206). That is, compared with the operation in the first embodiment shown in FIG. 4, the second embodiment is different from the first embodiment in that operations corresponding to steps S103 and S104 are not executed and the constant speed conveyance is not performed in the roll diameter calculation mode.

[Third Embodiment]
Based on FIG. 8 and FIG. 9, a third embodiment of the present invention will be described. FIG. 8 is a chart showing the calculation timing of the roll diameter in the third embodiment, and FIG. 9 is a flowchart showing the operation executed in the third embodiment. The third embodiment is different from the second embodiment in the timing of starting the image recording process, but other basic device configurations and operations are the same as those in the second embodiment. Therefore, description of portions common to the second embodiment is omitted. In the third embodiment, it is needless to say that the same effects as those of the second embodiment can be obtained by providing the same configuration as that of the second embodiment.

  In the third embodiment, as shown in FIG. 8, when the roll diameter of the sheet S on the feeding shaft 20 is calculated in a state where the sheet S is accelerated in the forward direction, the image recording process is started immediately after that. . That is, the recording transport mode is started immediately after the roll diameter is calculated. In the second embodiment, the recording speed is constant at the speed Vp. In the third embodiment, the speed from the speed V1 at the time when the roll diameter is calculated to the speed V2 at the subsequent constant speed conveyance. Becomes the conveyance speed Vp for recording.

  Originally, in order to perform precise image recording, it is desirable to start the image recording process in a state where the sheet S is conveyed at a constant speed, but if the accuracy of control using the pts signal is sufficiently ensured, the sheet The image recording process can be performed even in a state where S is accelerated. According to the third embodiment, after calculating the roll diameter of the sheet S on the feeding shaft 20 in a state where the forward conveyance speed of the sheet S is accelerated toward the speed Vp, the conveyance speed of the sheet S is fixed. Since the image recording process is performed on the sheet S until the speed V2 is reached, the waste of the sheet S can be further suppressed.

  Based on FIG. 9, an operation performed by the printer control unit 200 will be described. When a command signal for starting image recording processing is sent to the printer control unit 200 via the host control unit 100, the printer control unit 200 sets the outer diameter of the core tube as the roll diameter of the sheet S on the feeding shaft 20. (Step S301). Next, the printer control unit 200 accelerates the sheet S in the forward direction (step S302), and calculates the roll diameter while accelerating the sheet S (YES in step S303). The image recording process to S is started (step S304). Thereafter, when the conveyance speed of the sheet S reaches the speed V2 (step S305, YES), the acceleration of the sheet S is stopped and the constant speed conveyance is performed at the speed V2 (step S306). That is, as compared with the operation in the second embodiment shown in FIG. 7, in the second embodiment, step S206 for starting the image recording process is executed after realizing the constant speed conveyance of the sheet S. The third embodiment is different in that the image recording process is started immediately after the roll diameter is calculated.

[Fourth Embodiment]
Based on FIGS. 10-12, 4th Embodiment of this invention is described. FIG. 10 is a chart showing the calculation timing of the roll diameter in the fourth embodiment, FIG. 11 is a flowchart showing the operation executed in the fourth embodiment, and FIG. 12 is in the reverse direction of the sheet in the fourth embodiment. It is a figure explaining the conveyance distance. In the fourth embodiment, there is a period in which the sheet S is conveyed in the reverse direction in the roll diameter calculation mode, and the roll diameter is calculated in that period. The apparatus configuration and operation are the same as in the first embodiment. Therefore, description of portions common to the first embodiment is omitted. In the fourth embodiment, it is needless to say that the same effects as those of the first embodiment can be obtained by providing the same configuration as that of the first embodiment.

  In the fourth embodiment, the printer control unit 200 controls the motors M20, M31, M32, and M40 so that the sheet S can be conveyed in the reverse direction. Then, after accelerating the sheet S in the reverse direction until the conveyance speed in the reverse direction of the sheet S reaches the speed V1 at the time t0 to t1, the sheet S is conveyed at the constant speed in the reverse direction at the speed V1 at the time t1 to t2. Subsequently, at time t2 to t4, the sheet S is accelerated in the forward direction until the conveyance speed in the forward direction of the sheet S reaches the recording speed Vp.

  In this way, in the roll diameter calculation mode, the sheet S is transported in the reverse direction opposite to the forward direction, which is the transport direction in the recording transport mode, so that the sheet S is moved in the forward direction before the recording transport mode is entered. The transported distance can be further reduced. Therefore, wasteful generation of the sheet S can be more effectively suppressed. Furthermore, in the fourth embodiment, during the time t1 to t2 in the roll diameter calculation mode, the sheet S is conveyed at a constant speed V1, and the printer control unit 200 performs the drum encoder E30 and the feeding shaft during the constant speed conveyance. Based on the output value from the encoder E20, the roll diameter of the sheet S on the feeding shaft 20 is calculated. When the conveyance speed of the sheet S is constant, the output value from the drum encoder E30 is stable, so that the calculation accuracy of the roll diameter of the sheet S on the feeding shaft 20 is improved, and as a result, the tension Ta of the sheet S is accurately determined. It becomes possible to control well.

  The area of the area A1 shown in FIG. 10 represents the distance that the sheet S is conveyed in the reverse direction in the roll diameter calculation mode, and the area of the area A2 is conveyed in the forward direction until the recording conveyance mode is executed. (Hereinafter referred to as “distance A1” and “distance A2”, respectively). When the distance A1 is larger than the distance A2, that is, when the conveyance distance in the reverse direction of the sheet S until the recording conveyance mode is executed is larger than the conveyance distance in the forward direction, the sheet S is wasted. It is possible to start the image recording process after time t4 without doing so. Even when the distance A1 is smaller than the distance A2, that is, when the conveyance distance in the reverse direction of the sheet S until the recording conveyance mode is executed is smaller than the conveyance distance in the forward direction. Since the conveyance distance in the forward direction of the sheet S can be reduced only by A1, the occurrence of waste of the sheet S can be suppressed.

  Based on FIG. 11, operations performed by the printer control unit 200 will be described. When a command signal for starting image recording processing is sent to the printer control unit 200 via the host control unit 100, the printer control unit 200 sets the outer diameter of the core tube as the roll diameter of the sheet S on the feeding shaft 20. (Step S401). Next, the printer control unit 200 accelerates the sheet S in the reverse direction (step S402). When the conveyance speed of the sheet S reaches the speed V1 (step S403, YES), acceleration of the sheet S in the reverse direction is stopped and constant speed conveyance is performed at the speed V1 (step S404). When the roll diameter of the sheet S on the feeding shaft 20 is calculated based on the output values from the drum encoder E30 and the feeding shaft encoder E20 during the constant speed conveyance of the sheet S (step S405, YES), the sheet S is moved in the forward direction. Accelerate (step S406). When the transport speed of the sheet S reaches the recording speed Vp (step S407, YES), the forward acceleration of the sheet S is stopped and the constant speed transport is performed at the recording speed Vp (step S408). Then, the image recording process is performed in a state where the sheet S is conveyed at a constant speed at the recording speed Vp (step S409).

  FIG. 12 is a diagram illustrating the conveyance distance of the sheet in the reverse direction in the fourth embodiment. FIG. 12 is a schematic diagram showing the front drive roller 31 and the functional units 51, 61, and 62 in a front view, and the sheet S in a top view. Here, it is assumed that there is a recorded area N1 in which image recording processing has already been performed on the sheet S when the roll diameter calculation mode is executed. The printer 1 in the present embodiment uses UV ink that is cured by irradiating ultraviolet rays. When the image recording process is interrupted in such a printer 1, the sheet S is transported until the end n on the opposite side of the recorded region N1 passes through the main curing UV lamp 62, and then the transport is stopped. May be performed. By doing so, it is possible to prevent uncured UV ink from contaminating each part of the printer 1 by leaving the UV ink in the recorded region N1 uncured. In this case, when the conveyance of the sheet S is resumed (t = t0), the end n on the reverse side of the recorded area N1 is positioned on the forward side with respect to the UV lamp 62 as shown in FIG. doing.

  As described above, when the image recording process is performed by restarting the conveyance of the sheet S in the forward direction from the state in which the end n on the reverse side of the recorded area N1 is positioned on the forward direction side of the recording head 51, the speed is increased. Even if the image recording process is started, the image recording process cannot be performed on the area N2 close to the opposite side of the recorded area N1, and the sheet S is wasted. In order to avoid such waste, the sheet S is conveyed by a distance A1 in the reverse direction by the time point when the conveyance of the sheet S in the reverse direction is finished (t = t3). By doing this, even if the sheet S is subsequently transported by the distance A2 in the forward direction until the transport speed of the sheet S reaches the recording speed Vp, the image recording process is started from the region N2 at the start of the image recording process (t = t4). This can be started (FIG. 12C), and waste of the sheet S can be prevented from occurring. That is, the distance A1 for transporting the sheet S in the reverse direction in the roll diameter calculation mode also takes into account the distance A2 for transporting the sheet S in the forward direction before the start of the image recording process. It is preferable to determine that the end n on the reverse side of the recorded area N1 is positioned on the reverse direction side of the recording head 51 at (t = t4). If the roll diameter is calculated while the sheet S is being conveyed in the reverse direction so that the image recording process can be started from the area N2, the sheet S is conveyed only for calculating the roll diameter. It is reasonable because there is no need to do so.

Further, while the sheet S is being conveyed in the reverse direction so that the image recording process can be started from the area N2 close to the reverse direction of the recorded area N1, the recorded area N1 and the front drive roller 31 are in the nip. It may pass between the rollers 31n. At this time, the surfaces of the front drive roller 31 and the nip roller 31n are made of urethane rubber, general-purpose NBR (Nitrile
Butadiene Rubber) and other materials may damage or alter the roller surface due to ink adhesion. Therefore, UV urethane rubber, silicon rubber, fluoro rubber, hydroxylation, which is less susceptible to UV ink attack. It is desirable to use nitrile rubber or the like. Alternatively, when there is a risk of increasing the cost by using a material that is resistant to attack of these UV inks, the following configuration may be used. That is, the front drive roller 31 and the nip roller 31n are separated from each other before the sheet S is conveyed in the reverse direction, and the sheet S is conveyed in the reverse direction by the rear drive motor M32, whereby the front drive roller 31 and the nip with UV ink are conveyed. An attack on the roller 31n can be prevented.

[Others]
In the above embodiment, the sheet S corresponds to the “recording medium” of the present invention, the “rotating shaft” of the present invention is configured by the feeding shaft 20 and the core tube C, and the feeding shaft encoder E20 is the “rotational speed” of the present invention. The drum encoder E30 corresponds to the “speed detection unit” of the present invention, the printer control unit 200 corresponds to the “control unit” of the present invention, and the forward direction is the “first direction” of the present invention. The reverse direction corresponds to the “second direction” of the present invention, the speed Vp corresponds to the “recording speed” of the present invention, and the recording head 51 corresponds to the “recording unit” 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. For example, in the above-described embodiment, the output value of the drum encoder E30 is used as the conveyance speed of the sheet S, but it is also possible to use the output value from the encoder provided in the front drive motor M31 or the rear drive motor M32. Moreover, you may employ | adopt apparatuses other than an encoder as a rotation speed detection part or a speed detection part.

  In the above embodiment, the case where the feeding tension Ma of the sheet S is adjusted by controlling the torque of the feeding motor M20 connected to the feeding shaft 20 has been described. However, the present invention can also be applied when adjusting the winding tension Tc of the sheet S by controlling the torque of the winding motor M40 connected to the winding shaft 40.

  In the first embodiment and the second embodiment, since the sheet is conveyed in the forward direction in the roll detection mode, at least some of the sheet S is wasted. Therefore, in order to eliminate the waste of the sheet S, the image recording process may be started after the sheet S is conveyed in the reverse direction after the roll diameter is calculated.

  In the fourth embodiment, the roll diameter is calculated in a state where the sheet S is conveyed at a constant speed V1 in the reverse direction. However, the roll diameter is not necessarily required to convey the sheet S in the reverse direction. May be calculated when the conveyance speed of the sheet S in the reverse direction is changing.

  The timing for starting the image recording process can be changed as appropriate as long as the roll diameter is detected and the sheet S is being conveyed in the forward direction. For example, in the first embodiment shown in FIG. 3, the image recording process may be started immediately after the roll diameter is calculated. In this case, V1 to Vp correspond to the “recording speed” of the present invention, and at the time t = t2, the roll diameter calculation mode is shifted to the recording transport mode. Alternatively, in the fourth embodiment shown in FIG. 10, if t = t3 or later when the conveyance direction of the sheet S is switched from the reverse direction to the forward direction, the image recording process is started before the sheet S is conveyed at the constant speed Vp. May be. In this case, assuming that the speed at the start of the image recording process is V2, V2 to Vp correspond to the “recording speed” of the present invention, and from the roll diameter calculation mode to the recording transport mode at the start of the image recording process. Will be transferred to.

  In the fourth embodiment, the distance A1 for transporting the sheet S in the reverse direction in the roll diameter calculation mode is set so that the image recording process can be resumed from the area N2 close to the reverse side of the recorded area N1. The distance A1 may be determined by other methods as appropriate. For example, when the steering distance at which the sheet S should be conveyed in the forward direction is known in order to complete the position adjustment in the width direction of the sheet S by the steering unit 7, the sheet S is conveyed in the reverse direction in the roll diameter calculation mode. The distance A1 may be set to be equal to or greater than the steering distance. Then, it is possible to prevent the waste of the sheet S generated by the sheet S being conveyed in the forward direction for the position adjustment by the steering unit 7.

DESCRIPTION OF SYMBOLS 1 ... Printer (image recording device), 7 ... Steering unit, 20 ... Feeding shaft (rotating shaft), 30 ... Platen drum, 51 ... Recording head (recording unit), 200 ... Printer control unit (control unit), E20 ... Feeding Axis encoder (rotation speed detector) E30 ... Drum encoder (speed detector), S ... Sheet (recording medium), N1 ... Recorded area, n ... End

Claims (9)

In a transport apparatus for transporting the recording medium in a first direction at a recording speed for image recording processing in which an image is recorded on the recording medium.
A rotating shaft that rotates in accordance with the conveyance speed of the recording medium in a state where the recording medium is wound in a roll;
A rotational speed detector for detecting the rotational speed of the rotary shaft;
A speed detection unit for detecting a conveyance speed of the recording medium;
The roll diameter of the recording medium wound around the rotation shaft is calculated from the rotation speed of the rotation shaft detected by the rotation speed detection unit and the conveyance speed of the recording medium detected by the speed detection unit. A control unit that adjusts the tension of the recording medium by rotating the rotating shaft with a torque corresponding to the roll diameter.
The controller, after executing a roll diameter calculation mode for calculating the roll diameter while conveying the recording medium in the first direction at a speed smaller than the recording speed in the first direction, A transport apparatus that executes a recording transport mode in which the recording medium is transported in the first direction at the recording speed while adjusting the tension of the recording medium based on a roll diameter. In a transport method for transporting the recording medium at a recording speed in a first direction for image recording processing in which an image is recorded on the recording medium,
The roll diameter of the recording medium wound around the rotating shaft is determined from the rotational speed of the rotating shaft that rotates in accordance with the conveying speed of the recording medium and the conveying speed of the recording medium while the recording medium is wound in a roll shape. In order to adjust the tension of the recording medium by calculating and rotating the rotating shaft with a torque corresponding to the roll diameter,
After executing the roll diameter calculation mode for calculating the roll diameter while conveying the recording medium in the first direction at a speed component in the first direction smaller than the recording speed, based on the roll diameter A conveyance method comprising: executing a recording conveyance mode in which the recording medium is conveyed in the first direction at the recording speed while adjusting a tension of the recording medium. In an image recording apparatus comprising a transport mechanism for transporting the recording medium in a first direction at a recording speed for image recording processing in which an image is recorded on the recording medium.
The transport mechanism is
A rotating shaft that rotates in accordance with the conveyance speed of the recording medium in a state where the recording medium is wound in a roll;
A rotational speed detector for detecting the rotational speed of the rotary shaft;
A speed detection unit for detecting a conveyance speed of the recording medium;
The roll diameter of the recording medium wound around the rotation shaft is calculated from the rotation speed of the rotation shaft detected by the rotation speed detection unit and the conveyance speed of the recording medium detected by the speed detection unit. A control unit that adjusts the tension of the recording medium by rotating the rotating shaft with a torque corresponding to the roll diameter.
The controller, after executing a roll diameter calculation mode for calculating the roll diameter while conveying the recording medium in the first direction at a speed smaller than the recording speed in the first direction, An image recording apparatus that executes a recording transport mode in which the recording medium is transported in the first direction at the recording speed while adjusting the tension of the recording medium based on a roll diameter. The image recording apparatus according to claim 3 , wherein the control unit calculates the roll diameter in a state where the recording medium is transported in the first direction at a constant speed that is smaller than the recording speed. The image recording apparatus according to claim 3 , wherein the control unit calculates the roll diameter in a state where the recording medium is accelerated in the first direction toward the recording speed. In an image recording apparatus comprising a transport mechanism for transporting the recording medium in a first direction at a recording speed for image recording processing in which an image is recorded on the recording medium.
The transport mechanism is
A rotating shaft that rotates in accordance with the conveyance speed of the recording medium in a state where the recording medium is wound in a roll;
A rotational speed detector for detecting the rotational speed of the rotary shaft;
A speed detection unit for detecting a conveyance speed of the recording medium;
The roll diameter of the recording medium wound around the rotation shaft is calculated from the rotation speed of the rotation shaft detected by the rotation speed detection unit and the conveyance speed of the recording medium detected by the speed detection unit. A control unit that adjusts the tension of the recording medium by rotating the rotating shaft with a torque corresponding to the roll diameter.
The controller is configured to calculate a roll diameter while conveying the recording medium in a second direction opposite to the first direction at a speed component in the first direction smaller than the recording speed. After executing the recording conveyance mode for conveying the recording medium in the first direction at the recording speed while adjusting the tension of the recording medium based on the roll diameter,
When the roll diameter calculation mode is executed, the image recording process has already been performed.
An end of the region on the second direction side is closer to the first direction than a recording unit that performs the image recording process.
If present, the control unit conveys the recording medium in the second direction so that the end of the recorded area is positioned on the second direction side of the recording unit in the roll diameter calculation mode. An image recording apparatus. A steering unit that adjusts the position of the recording medium in the width direction while the recording medium is being conveyed in the first direction;
In the roll diameter calculation mode, the control unit sets the distance for transporting the recording medium in the second direction until the position adjustment by the steering unit is completed after the recording medium is transported in the second direction. The image recording apparatus according to claim 6, wherein the image recording apparatus has a distance equal to or longer than a distance for transporting the recording medium in the first direction. The image recording apparatus according to claim 6, wherein the control unit calculates the roll diameter in a state where the recording medium is conveyed at a constant speed in the second direction. The image recording apparatus according to any one of claims 3 to 8 , wherein the control unit calculates a torque to be applied to the rotation shaft using the outer diameter of the rotation shaft as the roll diameter until the roll diameter can be calculated. .

Images