JP2015058616A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology which conducts printing while applying a proper tensile force to a recording medium even if the recording medium expands and contracts due to light irradiation.SOLUTION: A printer includes: a printing part 3U capable of discharging a liquid to a recording medium S; a support part 32 which supports the recording medium S, on which prints are made by the printing part 3U, while applying a tensile force to the recording medium S and delivers the recording medium S to which the liquid adheres; an irradiation part 81 which may apply light to the recording medium S delivered from the support part 32; and a take-up part 4 which takes up the recording medium S to which the light is applied.

Description

  The present invention relates to a printing apparatus having a process of irradiating a printed recording medium with light.

  In a technique for recording an image on a recording medium such as paper or a resin sheet, a liquid having photocurability such as ultraviolet curable ink is attached to the recording medium, and then the liquid is cured by irradiating the recording medium with light. There is something. Some printing apparatuses of this type control the tension applied to a recording medium to obtain a stable print quality. For example, in the image recording apparatus described in Patent Document 1, a sheet as a recording medium is wound around a drum, the tension of the sheet is detected by a tension sensor provided in the sheet conveyance path, and the tension of the sheet wound around the drum is kept constant. Print while keeping. Further, in this technique, the tension is detected in each of the feeding unit that feeds the roll-shaped sheet and the winding unit that winds the printed sheet, and the tension applied to the sheet in each part on the conveyance path is controlled.

JP2013-111780A (for example, FIG. 3)

  As a light source for irradiating the recording medium with light, there is a light source having a high light quantity in order to surely fix the ink on the recording medium. For this reason, the recording medium partially expands and contracts under the influence of heat from the light source, and as a result, it may be difficult to control the tension of the recording medium. In the above prior art, the recording head for ejecting ink onto the recording medium, the UV light source for irradiating the recording medium with light, the tension sensor for detecting the tension of the recording medium, and the drive roller for driving the recording medium in the transport direction of the recording medium. Since the heat source is arranged near the recording medium that is the target of tension control, the influence of heat caused by the light irradiation described above can be a problem.

  Some embodiments according to the present invention provide a technique capable of solving the above-described problems and performing printing while applying an appropriate tension to the recording medium even when the recording medium is expanded or contracted due to light irradiation. Is.

  According to one aspect of the present invention, there is provided a printing unit capable of ejecting a liquid onto a recording medium, the recording medium on which the liquid is attached, supported while applying tension to the recording medium on which the liquid is ejected by the printing unit. The printing apparatus includes: a support unit that sends out; an irradiation unit that can irradiate light onto the recording medium that is sent out from the support unit; and a winding unit that winds up the recording medium irradiated with light.

  In the printing apparatus having this configuration, the printing unit that discharges the liquid to the recording medium, the supporting unit that supports the recording medium and applies tension, and the irradiation unit that irradiates the recording medium with light are arranged in this order in the conveyance direction of the recording medium. It is arranged with. Therefore, even if the recording medium expands or contracts due to light irradiation from the irradiation unit, the influence is blocked by the support unit and is prevented from reaching the printing unit. As a result, according to the present invention, printing can be performed while applying an appropriate tension to the recording medium.

  The printing apparatus may further include a detection unit that detects the tension of the recording medium sent from the support unit, and a control unit that controls the winding speed of the winding unit based on the detection result of the detection unit. According to such a configuration, the tension of the recording medium on the conveyance path from the support section to the winding section, which changes due to the expansion and contraction of the recording medium due to heat from the irradiation section, is adjusted by the winding speed of the winding section. It can be adjusted by doing. Thereby, conveyance and winding of a recording medium can be performed smoothly.

  In this case, for example, the detection unit detects the tension of the recording medium before receiving the light irradiated from the irradiation unit, that is, the tension of the recording medium after being unloaded from the support unit and before receiving the light irradiation by the irradiation unit. May be detected. According to such a configuration, since the heat source is located between the detection unit and the winding unit whose operation is controlled based on the detection result, the recording medium is not affected by the expansion or contraction of the recording medium due to the heat. Can be wound up well.

  Further, for example, the printing unit includes a liquid supply unit capable of discharging a photocurable liquid onto the recording medium, and a primary irradiation unit that irradiates light onto the recording medium to which the liquid is attached, and the exposure of the recording medium by the irradiation unit. The amount may be larger than the exposure amount of the recording medium by the primary irradiation unit. In printing using a photo-curable liquid, there is a problem that when the liquid is carried on a recording medium while being in a liquid state, the printing quality deteriorates or the liquid contaminates the apparatus. Therefore, it is desirable that the liquid adhering to the recording medium is cured to some extent at an early stage. By providing the primary irradiation unit in the printing unit, the liquid adhering to the recording medium can be cured to a hardness suitable for conveyance. The primary irradiation unit may have a smaller amount of light than the subsequent irradiation unit, and therefore the amount of heat generated can be suppressed.Therefore, even if it is arranged upstream of the support unit in the transport direction, it has an effect on the tension control of the recording medium. It can be kept small. In addition, since the irradiation unit having a larger amount of light is provided on the downstream side in the transport direction, the liquid can be reliably cured and fixed on the recording medium.

  In this case, for example, the light source of the irradiation unit may be an ultraviolet lamp. Since the ultraviolet lamp can irradiate the recording medium with strong ultraviolet rays, it is effective for reliably curing the photocurable liquid. On the other hand, since there is a relatively large amount of heat generation, it is not suitable to be disposed between the printing unit and the support unit, and is preferably provided downstream of the support unit in the transport direction as described above. .

  Further, for example, the light source of the primary irradiation unit may be a light emitting diode. The primary irradiation part does not need to completely cure the photocurable liquid. Therefore, a light-emitting diode that cannot obtain a light amount as high as an ultraviolet lamp but has a relatively small amount of heat generation is suitable as a light source. In such a configuration, the photocurable liquid supplied to the recording medium can be cured to some extent, and the influence of heat on the print quality can be suppressed.

  Further, for example, the support unit may include a conveyance roller that moves the recording medium by winding the recording medium between the printing unit and the irradiation unit in the conveyance path of the recording medium and rotating the recording medium. According to such a configuration, the expansion and contraction of the recording medium due to the heat from the irradiation unit can be blocked by the support unit around which the recording medium is wound.

1 is a front view schematically illustrating a schematic configuration of a printing apparatus to which the present invention is applicable. FIG. 2 is a block diagram schematically showing an electrical configuration for controlling the printer shown in FIG. 1.

  FIG. 1 is a front view schematically illustrating a schematic configuration of a printing apparatus to which the present invention is applicable. In FIG. 1, an XYZ orthogonal coordinate system corresponding to the left-right direction X, the front-rear direction Y, and the vertical direction Z of the printing apparatus 1 is displayed in order to clarify the positional relationship between the respective units of the apparatus.

  In the printing apparatus 1, the feeding unit 2, the process unit 3, and the winding unit 4 are arranged in the left-right direction X. These functional units 2, 3, 4 are accommodated in an internal space IS surrounded by the housing member 11. Yes. The feeding unit 2 and the winding unit 4 have a feeding shaft 20 and a winding shaft 40, respectively. Then, both ends of a sheet S (web) which is a recording medium are wound around the feeding shaft 20 and the winding shaft 40 in a roll shape, and are stretched between them. The sheet S is transported from the feeding shaft 20 to the process unit 3 along the path Pc thus stretched, subjected to printing processing by the process unit 3U, and then transported to the winding shaft 40. 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. 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. In the following description, the terms “upstream side” and “downstream side” mean the upstream side and the downstream side in the sheet conveyance direction in the sheet conveyance path, respectively.

  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 on the paper surface of 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 can be attached to and detached 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. As will be described in detail later, the driven roller 21 is provided with a tension sensor S21 that detects the tension of the sheet S wound around the roller.

  The process unit 3 appropriately performs processing by the process unit 3U disposed along the outer peripheral surface of the rotating drum 30 while supporting the sheet S fed from the feeding unit 2 by the rotating drum 30 to form the sheet S. The image is printed. In the process unit 3, a front driving roller 31 and a rear driving roller 32 are provided on both sides of the rotating drum 30, and the sheet S conveyed from the front driving roller 31 to the rear driving roller 32 is rotated by the rotating drum 30. To receive an image print.

  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. And the front drive roller 31 conveys the sheet | seat S fed out from the feeding part 2 to the downstream of a conveyance path | route by rotating clockwise on the paper surface of FIG. 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 rotating drum 30 is a cylindrical drum having a center line parallel to the Y direction, and the sheet S is wound around the outer peripheral surface thereof. Further, the rotating drum 30 has a rotating shaft 302 extending in the axial direction through the cylindrical center line. The rotation shaft 302 is rotatably supported by a support mechanism (not shown), and the rotation drum 30 rotates about the rotation shaft 302.

  The sheet S conveyed from the front driving roller 30 to the rear driving roller 32 is wound around the outer peripheral surface of the rotating drum 30 from the back surface side. The rotating drum 30 supports the sheet S from the back side while receiving the frictional force between the rotating drum 30 and rotating in the conveyance direction Ds of the sheet S. Incidentally, the process section 3 is provided with driven rollers 33 and 34 for folding the sheet S on both sides of the winding section around the rotating drum 30. Among these, the driven roller 33 wraps the surface of the sheet S between the front drive roller 31 and the rotating drum 30 and folds the sheet S. On the other hand, the driven roller 34 wraps the surface of the sheet S between the rotating 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, a long winding portion of the sheet S around the rotating drum 30 can be secured.

  The rear driving 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 rotating 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 on the paper surface of 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. As will be described in detail later, the rotary drum 30 is provided with a drum encoder E30 for detecting the rotational position, and the driven roller 34 is a tension sensor S34 for detecting the tension of the sheet S wound around the roller. Is provided.

  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 rotating drum 30. In the process unit 3, a process unit 3 </ b> U is provided for printing a color image on the surface of the sheet S supported by the rotating drum 30. The process unit 3U has a configuration in which the print heads 36a to 36d and the UV irradiators 37a to 37c and 38 are supported by the unit support member 35. The unit support member 35 sandwiches the print heads 36 a to 36 d and the UV irradiators 37 a to 37 c and 38 from the front-rear direction Y by two unit support flat plates having an arc shape along the circumferential shape of the rotating drum 30. Support with. As shown in FIG. 1, there is a gap Δ between the unit support member 35 (unit support flat plate) and the rotating drum 30.

  The four print heads 36a to 36d arranged in order in the transport direction Ds correspond to yellow, cyan, magenta, and black, and eject inks of the corresponding colors from the nozzles by an inkjet method. These four print heads 36 a to 36 d are arranged radially from the rotating shaft 302 of the rotating drum 30 and are arranged along the outer peripheral surface of the rotating drum 30. The print heads 36a to 36d are positioned with respect to the rotating drum 30 by the unit support member 35 and face the rotating drum 30 with a slight clearance (platen gap). Accordingly, the print heads 36a to 36d face the surface of the sheet S wound around the rotating drum 30 with a predetermined paper gap. When the paper gap is defined by the unit support member 35 in this way, each of the print heads 36a to 36d ejects ink, so that the ink is landed at a desired position on the surface of the sheet S, and a color image is formed on the surface of the sheet S. It is formed.

  As the ink used in the print heads 36a to 36d, UV (ultraviolet) ink (photo-curable ink) that is cured by irradiating ultraviolet rays (light) is used. Therefore, in the process unit 3U, UV irradiators 37a to 37c and 38 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. Temporary curing UV irradiators 37a to 37c are arranged between the four print heads 36a to 36d. Specifically, the first UV irradiator 37a is positioned downstream of the first print head 36a on the most upstream side in the transport direction Ds, and the second UV irradiator 37b is positioned downstream of the second print head 36b. A third UV irradiator 37c is disposed downstream of the third print head 36c. The UV irradiators 37a to 37c irradiate ultraviolet rays having a relatively weak irradiation intensity so that the ink is cured (temporarily cured) to a degree that the wetting and spreading of the ink is sufficiently slower than the case where the ultraviolet rays are not irradiated. Yes, it does not fully cure the ink.

  On the other hand, a UV irradiator 38 for main curing is provided on the downstream side in the transport direction Ds with respect to the four print heads 36a to 36d. That is, the UV irradiator 38 is cured (mainly cured) to such an extent that ink wetting and spreading are stopped by irradiating ultraviolet rays having a stronger irradiation intensity than the UV irradiators 37a to 37c. By performing the temporary curing and the main curing in this way, the color images formed by the plurality of print heads 36a to 36d can be fixed on the surface of the sheet S.

  The UV irradiator 38 includes a cooling mechanism for cooling a light source that irradiates ultraviolet rays. The cooling mechanism cools the light source using an airflow that takes in air from the outside of the housing member 11 and discharges the air to the outside of the housing member 11. Therefore, the housing member 11 is provided with an intake port 51 for taking in air from the outside and an exhaust port 53 for discharging air to the outside with respect to the UV irradiator 38. Specifically, the intake port 51 and the exhaust port 53 are configured by louvers or the like that open to the housing member 11. Further, inside the housing member 11, an intake duct 55 extending from the intake port 51 to the UV irradiator 38 and an exhaust duct 57 extending from the UV irradiator 38 to the exhaust port 53 are provided for the UV irradiator 38. ing.

  An intake fan 67 is provided inside the intake duct 55, and an exhaust fan 68 is provided inside the exhaust duct 57. By the operation of these fans, the air is sucked from the intake port 51, and the inside of the intake duct 55 is provided. The air flow AF discharged from the exhaust port 53 is generated through the air flow path Pg1 formed at the top, the upper end portion of the UV irradiator 38, and the air flow path Pg2 formed inside the exhaust duct 57. Due to this air flow AF, heat generated from the UV irradiator 38 is discharged outside the apparatus.

  In this way, the print heads 36a to 36d and the UV irradiators 37a to 37c and 38 are mounted on the unit support member 35, thereby configuring the process unit 3U. The unit support member 35 is supported by two rails 351 extending in the front-rear direction Y, and further on the rail 351 in the front-rear direction Y with print heads 36a to 36d and UV irradiators 37a to 37c, 38. It is movable. That is, the process unit 3U is movable in the front-rear direction Y. As a result, the process unit 3U has a printing position in the front-rear direction Y that is arranged at substantially the same position as the feeding unit 2 and the winding unit 4, and a maintenance position in which the feeding unit 2 and the winding unit 4 have significantly different Y-direction positions. It is possible to move between. With the process unit 3U positioned at the printing position, it is possible to form the conveyance path Pc of the sheet S from the feeding unit 2 through the process unit 3 to the winding unit 4, and the process unit 3U performs printing on the sheet S. Can do. On the other hand, when the process unit 3U is in the maintenance position, the process unit 3U is exposed to the external space, and various maintenance operations such as parts replacement by the operator can be performed.

  The sheet S on which the color image is formed by the process unit 3 is conveyed to the winding unit 4 by the rear drive roller 32. The winding unit 4 has a driven roller 41 that winds the sheet S from the back surface 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 on the paper surface of 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 can be attached to and detached 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 apparatus configuration of the printing apparatus 1. Subsequently, an electrical configuration for controlling the printing apparatus 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 printing apparatus 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 printing apparatus 1 is provided with a printer control unit 200 that controls each unit of the printing apparatus 1 in accordance with a command from the host computer 10. The printing head, the UV irradiators 37 a to 37 c and 38, and each unit of the sheet conveyance system are 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 of the print heads 36 a to 36 d that form 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 the drum encoder E30 that is attached to the rotating shaft of the rotating drum 30 and detects the rotating position of the rotating drum 30. Is done. That is, since the rotating drum 30 is driven to rotate as the sheet S is conveyed, the conveying position of the sheet S can be grasped by referring to the output of the drum encoder E30 that detects the rotating position of the rotating drum 30. it can. 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 of the print heads 36a to 36d based on the pts signal, whereby each print head. The ink ejected by 36a to 36d is landed on the target position of the conveyed sheet S to form a color image.

  Further, the printer controller 200 also controls the timing of turning on / off the UV irradiators 37 a to 37 c and 38 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. 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. That is, a tension sensor S21 that detects the tension of the sheet S wound around the roller 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. Then, the printer control unit 200 adjusts the tension applied to the sheet S supplied from the feeding unit 20 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 printing apparatus 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 of the sheet S from the front drive roller 31 to the rear drive roller 32. That is, a tension sensor S34 that detects the tension of the sheet S wound around the roller is attached to the driven roller 34 disposed between the rotating 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 control unit 200 adjusts the tension applied to 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 of the sheet S from the rear drive roller 32 to the winding shaft 40. That is, a tension sensor S41 for detecting the tension of the sheet S wound around the roller is attached to the driven roller 41 disposed between the rear drive roller 32 and the take-up 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 tension applied to the sheet S by feedback controlling the torque of the winding motor M40 based on the detection result of the tension sensor S41.

  In the above-described configuration of the sheet conveyance system, for the sheet S that is wound around the rotating drum 30 and receives the printing process from the process unit 3U, the rear drive roller 32 is based on the detection result of the tension sensor S34 that accompanies the driven roller 34. By controlling the rotation, the tension is kept constant and stable printing processing is possible.

  On the other hand, for the sheet S conveyed from the feeding unit 2 to the process unit 3, the position of the feeding shaft 20 and the driven roller 21 is controlled based on the detection result of the tension sensor S 21 attached to the driven roller 21. It is possible to prevent S from sagging and excessive or insufficient supply. Further, with respect to the sheet S carried out from the process unit 3 to the winding unit 4, the rotation of the winding shaft 40 is controlled based on the detection result of the tension sensor S41 associated with the driven roller 41, so that the sheet S is slack. It is possible to prevent excessive or insufficient winding.

  The above is the outline of the electrical configuration for controlling the printing apparatus 1. As described above, the front drive roller 31 rotates at a predetermined speed, whereby the sheet S is conveyed at a constant speed along the conveyance path Pc. Then, the printer control unit 200 adjusts the tension applied to the sheet S after controlling the conveyance speed of the sheet S to a constant speed.

  Returning to FIG. 1, the configuration of the printing apparatus 1 will be further described. An external light irradiation unit 8 can be attached as an optional unit to the printing apparatus 1 configured as described above. This light irradiation unit 8 is a total exposure amount of light irradiated in the printing apparatus 1 with respect to the sheet S printed by the printing apparatus 1 (time integrated value of irradiation light amount by each of the UV irradiators 37a to 37c, 38). The sheet S is irradiated with UV light with an exposure amount larger than (). As the UV irradiators 37a to 37c and 38 included in the process unit 3U, it is preferable to use an LED (light emitting diode) having a relatively small calorific value as a light source in order to suppress the temperature rise of the unit. However, depending on the characteristics of the photocurable ink and the sheet S, it may not be possible to provide an exposure amount sufficient to cure the ink to a required hardness only with the UV irradiator using the LED as a light source. .

  In order to make it possible to cure the ink more reliably in response to such a situation, the printing apparatus 1 has a configuration in which an external light irradiation unit 8 can be mounted as necessary. . As shown in FIG. 1, the light irradiation unit 8 includes a plurality of driven rollers 801 to 806 that form an external transport path Px by winding and rotating the sheet S after passing the driven roller 41, and external transport. And a UV lamp 81 for irradiating the sheet S conveyed along the path Px with ultraviolet rays. The sheet S conveyed through the external conveyance path Px and irradiated with ultraviolet rays is returned to the main body of the printing apparatus 1 and taken up by the take-up shaft 40.

  Among the driven rollers 801 to 804, the roller 801 provided at the most upstream side in the sheet conveying direction, that is, the closest position of the driven roller 41 on the main body side, changes the posture of the sheet S wound around the driven roller 41 to the light irradiation unit 8. It is a posture maintenance roller for maintaining almost the same as when not mounted. That is, the posture maintaining roller 801 is disposed in the vicinity of the path of the sheet S from the driven roller 41 toward the take-up shaft 40 when the light irradiation unit 8 is not attached. Thus, the amount of the sheet S wound around the driven roller 41 is prevented from changing greatly depending on whether or not the light irradiation unit 8 is attached, and the variation in detection accuracy by the tension sensor S41 attached to the driven roller 41 can be suppressed. it can.

  The UV lamp 81 includes a lamp light source such as a high-pressure mercury lamp, a low-pressure mercury lamp, or a metal halide lamp, and supplies a larger amount of light to the sheet S than the UV irradiators 37 a to 37 c and 38 that use LEDs as a light source. Specifically, the UV lamp 81 exposes the sheet S in a wavelength component effective for curing the photocurable ink, rather than the total exposure amount that the UV irradiators 37a to 37c and 38 expose the sheet S. The exposure amount is larger. Therefore, the photocurable ink that adheres to the sheet S can be more reliably cured. The turning on / off of the UV lamp 81 may be controlled by the printer control unit 200, or may be controlled by a control unit provided in the light irradiation unit 8 independently of this.

  Even when the UV lamp 81 having a large irradiation light amount is provided as described above, it is not realistic to omit the UV irradiator in the process unit 3U because the sheet S to which the ink is attached needs to be conveyed. On the other hand, it is not realistic to provide the lamp light source in the process unit 3U because of the amount of heat generated. Accordingly, the lamp light source is preferably provided downstream of the process unit 3U in the sheet conveyance path, separately from the process unit 3U. In this case, the position where the lamp light source is provided downstream of the process unit 3U can be considered as follows.

  As described above, since the UV lamp generates a large amount of heat, the sheet S may expand and contract due to the influence of heat. In particular, when the sheet S is a film system such as a resin film, expansion and contraction due to heat is likely to occur. For this reason, if a lamp light source is provided between the process unit 3U and the rear drive roller 32, the sheet S expands and contracts between the process unit 3U and the rear drive roller 32 at a position facing the process unit 3U. There is a problem that it is difficult to keep the tension and the conveyance speed constant.

  On the other hand, if the lamp light source is provided on the downstream side of the rear drive roller 32, a heat source does not enter between the process unit 3U and the rear drive roller 32 that controls the sheet conveyance here, and thus the above-described problem occurs. Does not occur. In addition, since the sheet S is wound around the rear driving roller 32 and firmly supported, the expansion and contraction of the sheet S occurring on the downstream side of the rear driving roller 32 is blocked by the rear driving roller 32, and from the rear driving roller 32. Is also prevented from propagating to the upstream process unit 3U.

  On the downstream side of the rear drive roller 32, the tension of the sheet S is detected by a tension sensor S41 associated with the driven roller 41, and the rotation of the winding shaft 40 is controlled. By arranging the lamp light source on this path, it is conceivable that the rotation control is affected by the expansion and contraction of the sheet S due to heat. However, the rotation control here is sufficient if the sheet S carried out from the process unit 3 by the rear drive roller 32 can be wound around the winding shaft 40 without excess or shortage, and the sheet in the process unit 3 related to print quality is sufficient. Compared to transport, the required accuracy is relatively low. And the load torque which increases by adding the driven rollers 801-806 becomes the load of the winding shaft 40, and does not become the load of the rear drive roller 32. Therefore, it is not necessary to change the mode of sheet conveyance control by the rear drive roller 32 depending on whether or not the light irradiation unit 8 is attached. As described above, it is desirable that the lamp light source is provided at least downstream in the sheet conveyance direction with respect to the rear drive roller 32 in the sheet conveyance path.

  Next, whether the lamp light source is provided between the rear drive roller 32 and the driven roller 41 or between the driven roller 41 and the take-up shaft 40 will be examined. From the viewpoint of controlling the rotation of the winding shaft 40, there is no significant difference whether the lamp light source is on the upstream side or the downstream side of the driven roller 41. In the example shown in FIG. 1, a UV lamp 81 is provided between the driven roller 41 and the take-up shaft 40 along the conveyance path Px that draws the sheet S to the outside. That is, the lamp light source is provided on the downstream side of the driven roller 41.

  In such a configuration, the influence of the expansion and contraction of the sheet S due to the heat from the UV lamp 81 is exerted on the rear drive roller 32 because the driven roller 41 is interposed on the conveyance path between the rear drive roller 32 and the UV lamp 81. Can be suppressed. Further, since the amount of the sheet S wound around the rear drive roller 32 does not change depending on the presence or absence of the light irradiation unit 8, the sheet S can be stably conveyed by the rear drive roller 32.

  In addition, the light irradiation unit 8 does not have a driving roller, and the rollers 801 to 806 that wrap the sheet S to form the conveyance path Px are all driven rollers. It is preferable that the sheet S is provided as close as possible in order to convey the sheet S satisfactorily.

  As described above, in the printing apparatus 1 of this embodiment, the UV lamp 81 that generates a large amount of heat and may affect the sheet S due to heat is controlled by the rear drive roller 32 that controls the sheet conveyance in the process unit 3. Also, it is arranged to face the sheet S on the downstream side in the sheet conveying direction. According to such a configuration, even when the sheet S expands and contracts due to heat from the UV lamp 81, the influence is prevented from reaching the process unit 3 upstream of the rear drive roller 32, and the process unit In 3, the printing process can be performed while applying an appropriate tension to the sheet S.

  In the printing apparatus 1, the tension of the sheet S carried out from the rear drive roller 32 is detected by the tension roller S 41 attached to the driven roller 41, and the rotation of the winding shaft 40 is controlled based on the detection result. . Thereby, it is possible to wind up the sheet S carried out from the rear drive roller 32 without excess or deficiency. Further, even when the sheet S expands or contracts due to heat from the UV lamp 81 on the sheet conveyance path after the rear drive roller 32, a change in tension caused by the detection is detected and the winding speed is adjusted. Occurrence of slack and poor winding are prevented.

  In the sheet conveyance path after the rear driving roller 32, the driven roller 41 including the tension roller S41, the UV lamp 81, and the winding shaft 40 are arranged in this order along the sheet conveyance direction. That is, a heat source exists between a position where the tension of the sheet S is detected and a position where a winding force for winding the sheet S is generated. By arranging the heat source in the control loop from the tension detection to the rotation control of the winding shaft 40, it is possible to control the winding of the sheet S including the influence of the sheet expansion and contraction due to heat. As a result, the sheet S can be stably conveyed after the rear drive roller 32.

  In addition, the process unit 3U of the printing apparatus 1 includes print heads 36a to 36d that attach the photocurable ink to the sheet S by inkjet printing, and UV that irradiates the sheet S with light (ultraviolet rays) and cures the ink. Irradiators 37a to 37c, 38 are included. These UV irradiators 37a to 37c, 38 have a smaller irradiation light quantity but a smaller calorific value than the UV lamp 81 provided in the light irradiation unit 8. Since the UV irradiators 37a to 37c and 38 having such a small amount of heat generation are less likely to expand and contract the sheet S, they can be provided in the process unit 3U, and this makes it difficult to at least transport the photocurable ink. It can be cured rapidly to the extent that there is no ink.

  In addition, the light source of the light irradiation unit 8 provided outside the process unit 3 is a UV lamp, which can irradiate the sheet S with strong light, while the UV irradiators 37 a to 37 c provided in the process unit 3. The light source 38 is an LED, which can reduce the amount of heat generated.

  In addition, since the rear drive roller 32 that winds and conveys the sheet S between the process unit 3U and the UV lamp 81 is provided, the influence of the expansion and contraction of the sheet S due to heat from the UV lamp 81 is exerted on the rear drive roller. 32 and is prevented from reaching the process unit 3U.

  As described above, in this embodiment, the sheet S corresponds to the “recording medium” of the present invention. The process unit 3U functions as the “printing unit” of the present invention, of which the print heads 36a to 36d are the “liquid supply unit” of the present invention, and the UV irradiators 37a to 37c and 38 are the “primary irradiation” of the present invention. Part ". Further, the rear drive roller 32 functions as a “support portion” and a “conveyance roller” of the present invention. Further, the light irradiation unit 8, particularly the UV lamp 81 functions as the “irradiation unit” of the present invention, and the tension sensor S 41 and the printer control unit 200 function as the “detection unit” and “control unit” of the present invention, respectively. ing.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the light irradiation unit 8 is configured as an optional unit that can be attached to and detached from the main body of the printing apparatus 1, but the present invention also applies when the light irradiation unit is incorporated in the main body as part of the printing apparatus. Is valid. In this embodiment, provisional curing UV irradiators 37a to 37c and a main curing UV irradiator 38 are provided as "primary irradiators" provided in the process unit 3U. When incorporated in the apparatus main body, this functions as a main curing irradiator, so the main curing UV irradiator in the process unit 3U may be equivalent to that for temporary curing.

  Further, for example, in the above embodiment, the light irradiation unit 8 having the UV lamp 81 is provided between the driven roller 41 having the tension sensor S41 and the take-up shaft 40 in the sheet conveyance path. A UV lamp may be provided in the conveyance path between the roller 32 and the driven roller 41.

  Further, for example, in the above embodiment, in a state where the light irradiation unit 8 is mounted, the sheet S is pulled out from the main body of the printing apparatus 1 and is transported along the transport path Px in the light irradiation unit 8. Although the light irradiation from 81 is received, the sheet conveyance path may be common regardless of the presence or absence of the light irradiation unit, and only the UV lamp may be attached and detached.

  In the above-described embodiment, the printing unit includes four print heads 36a to 36d and forms a color image. However, the number of print heads and ink colors is not limited to this. For example, a single color ink is used. The present invention can also be applied to an apparatus that forms a monochrome image.

  In addition, the printing apparatus of the above embodiment is an apparatus that prints an image by attaching a photocurable ink to a long sheet S as a recording medium by an inkjet method, but the type of the recording medium is not limited to this and is arbitrary. Can be used. Further, what is attached to the recording medium is not limited to ink as long as it is a photocurable liquid, and the purpose of printing is not limited to image formation.

  DESCRIPTION OF SYMBOLS 1 ... Printing apparatus, 8 ... Light irradiation unit (irradiation part), 3U ... Process unit (printing part), 4 ... Winding part, 32 ... Rear drive roller (support part, conveyance roller), 36a-36d ... Print head ( Liquid supply unit), 37a to 37c, 38 ... UV irradiator (primary irradiation unit), 40 ... Winding shaft, 81 ... UV lamp (irradiation unit), 200 ... Printer control unit (control unit), S ... Sheet (recording) Medium), S41 ... tension sensor (detector)

Claims (7)

A printing unit capable of discharging liquid onto a recording medium;
A support unit for supporting the recording medium from which the liquid is discharged by the printing unit while applying tension, and feeding the recording medium to which the liquid is attached;
An irradiation unit capable of irradiating light to the recording medium sent from the support unit;
A printing apparatus comprising: a winding unit that winds up the recording medium irradiated with light. A detection unit for detecting a tension of the recording medium sent from the support unit;
The printing apparatus according to claim 1, further comprising: a control unit that controls a winding speed of the winding unit based on a detection result of the detection unit.   The printing apparatus according to claim 2, wherein the detection unit detects a tension of the recording medium before receiving the light irradiated from the irradiation unit. The printing unit includes a liquid supply unit capable of discharging the photocurable liquid to the recording medium, and a primary irradiation unit that irradiates light to the recording medium to which the liquid is attached,
The printing apparatus according to claim 1, wherein an exposure amount of the recording medium by the irradiation unit is larger than an exposure amount of the recording medium by the primary irradiation unit.   The printing apparatus according to claim 4, wherein a light source of the irradiation unit is an ultraviolet lamp.   The printing apparatus according to claim 5, wherein a light source of the primary irradiation unit is a light emitting diode.   The said support part has a conveyance roller which moves the said recording medium by winding and rotating the said recording medium between the said printing part and the said irradiation part among the conveyance paths of the said recording medium. The printing apparatus according to claim 6.

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