JP6019708B2 - Drawing apparatus and drawing method - Google Patents

Description

  The present invention relates to a drawing apparatus and a drawing method.

2. Description of the Related Art Conventionally, an arbitrary drawing medium that includes a transport drum and a discharge head that is disposed so as to discharge liquid droplets toward the outer surface of the transport drum and that is transported while being held in a state of following the outer peripheral surface of the transport drum. 2. Description of the Related Art A drawing apparatus is known that forms an image on a drawing medium by landing droplets discharged from a discharge head at a position.
The droplets ejected from the ejection head toward the drawing medium being conveyed and moving are determined by the moving speed of the drawing medium and the flight time until the ejected droplets land on the drawing medium. Land in position. The flight time until the ejected droplets land on the drawing medium is determined by the flying speed of the droplets and the distance between the ejection head and the drawing medium. Therefore, in order to cause the droplet to land accurately at a predetermined position on the drawing medium, it is necessary to maintain the distance between the ejection head and the drawing medium (hereinafter referred to as “head gap”) at an appropriate distance. is necessary.

  Patent Document 1 discloses a drum that holds and rotates a medium on an outer peripheral portion, a head that ejects fluid onto the medium held on the drum, and a fixing unit that fixes the fluid on the medium ejected by the head. And an outer diameter measuring unit for measuring the outer diameter of the drum, an adjusting unit for adjusting the distance between the drum and the head, and a head according to a variation in the outer diameter of the drum measured by the outer diameter measuring unit. A fluid ejecting apparatus including a controller that causes an adjustment unit to adjust a distance from a medium is disclosed. In this fluid ejecting apparatus, even if the outer diameter of the drum fluctuates, the outer diameter measuring unit measures the outer diameter of the drum, and the adjustment unit adjusts the distance between the drum and the head according to the measured value. The distance between the drum and the head can be kept at an appropriate distance. This prevents the landing position on the medium from fluctuating due to fluctuations in the distance between the drum and the head due to fluctuations in the outer diameter of the drum, and landing the fluid at an appropriate position on the medium. Can be made. Patent Document 1 discloses a laser type (light sensor type) and a contact type as an outer diameter measuring unit.

  Japanese Patent Application Laid-Open No. 2004-228867 faces a medium feeding means for feeding a recording medium along a feeding path that follows the outer circumferential surface by a rotating body that feeds the recording medium in close contact with the outer circumferential surface, and a recording medium that is fed. An ink jet head that performs printing, a gap adjusting means for adjusting the gap between the nozzle surface of the ink jet head and the recording surface of the recording medium by moving the ink jet head back and forth in the normal direction of the outer peripheral surface, A drawing apparatus is disclosed that includes a gap measuring unit that measures the gap and a control unit that controls the gap adjusting unit so that the gap becomes an appropriate value based on the measurement result of the gap measuring unit. According to the drawing apparatus, the landing position on the medium changes due to the change in the distance between the drum and the head due to the change in the position of the outer peripheral surface of the rotary body (the outer diameter of the rotary body). The drawing process can be performed with high accuracy. Patent Document 2 discloses an ultrasonic type, a laser type (optical sensor type), a contact type, and a magnetic sensor type as a gap measuring means.

JP 2010-5860 A JP 2011-126082 A

  However, the outer diameter measuring unit disclosed in Patent Document 1 and the gap measuring means disclosed in Patent Document 2 measure the position of the outer peripheral surface of the drum or the rotating body with respect to the reference position. Therefore, the accuracy of the relative position between the outer diameter measuring unit and the gap measuring means and the reference position affects the accuracy of the measurement value. For this reason, in order to ensure the measurement accuracy, it is necessary to accurately position the outer diameter measuring unit and the gap measuring means and to suppress the position variation within the allowable error range. In order to make the support device for the outer diameter measuring part and the gap measuring means highly accurate and highly rigid, there is a problem that the support device becomes large and the manufacturing cost becomes high.

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

  Application Example 1 A drawing apparatus according to this application example includes a conveyance drum that sends a drawing medium in close contact with an outer peripheral surface, and a nozzle surface in which a discharge nozzle that discharges a liquid material is opened. Detected by a discharge head disposed at a position facing the outer peripheral surface, a head displacement device that moves the discharge head back and forth in the normal direction of the outer peripheral surface, a temperature sensor that detects the temperature of the transport drum, and the temperature sensor And a head distance adjusting unit that controls the head displacement device based on the temperature of the transport drum and adjusts the distance between the nozzle surface and the outer peripheral surface.

  According to the drawing apparatus according to this application example, the distance between the nozzle surface and the outer peripheral surface can be changed by moving the ejection head back and forth in the normal direction of the outer peripheral surface by the head displacement device. By detecting the temperature of the transport drum by the temperature sensor, a change in the diameter of the transport drum due to the temperature change can be obtained. The head distance adjustment unit controls the head displacement device based on the temperature of the transport drum detected by the temperature sensor and adjusts the distance between the nozzle surface and the outer peripheral surface, thereby changing the temperature of the transport drum. The distance between the nozzle surface and the outer peripheral surface can be maintained at an appropriate distance in response to the resulting change in the diameter of the transport drum.

  Application Example 2 In the drawing apparatus according to the application example, it is preferable that the liquid material is a photo-curing liquid material and further includes a curing light source that emits curing light.

  According to this drawing apparatus, the liquid material handled by the drawing apparatus is a photocurable liquid material. The curing light source is used to promote the curing of the liquid material that has landed on the drawing medium. For this reason, the curing light is often irradiated toward the drawing medium held on the outer peripheral surface of the transport drum. In many cases, heat is emitted from the light source of the curing light together with the curing light. There is a high possibility that the temperature of the transport drum is raised by the irradiation of the heat. That is, there is a high possibility that the diameter of the transport drum is changed by the heat irradiated with the curing light and the distance between the nozzle surface and the outer peripheral surface is changed. By controlling the head displacement device based on the temperature of the transport drum and adjusting the distance between the nozzle surface and the outer peripheral surface, the diameter of the transport drum caused by the heat irradiated with the curing light irradiation The distance between the nozzle surface and the outer peripheral surface can be maintained at an appropriate distance in response to the change in.

  Application Example 3 A drawing method according to this application example includes a transport drum that sends a drawing medium in close contact with an outer peripheral surface, and a nozzle surface in which a discharge nozzle that discharges a liquid material is opened. A drawing method for drawing an image on the drawing medium using a discharge head disposed at a position facing an outer peripheral surface, the drum temperature detecting step for detecting the temperature of the transport drum, and the drum temperature And a head distance adjusting step of adjusting a distance between the nozzle surface and the outer peripheral surface based on the temperature of the conveying drum detected in the detecting step.

  According to the drawing method according to this application example, the change in the diameter of the conveyance drum caused by the temperature change can be obtained by detecting the temperature of the conveyance drum in the drum temperature detection step. In the head distance adjustment process, the diameter of the transport drum caused by the temperature change of the transport drum is adjusted by adjusting the distance between the nozzle surface and the outer peripheral surface based on the temperature of the transport drum detected in the drum temperature detection process. The distance between the nozzle surface and the outer peripheral surface can be maintained at an appropriate distance in response to the change in.

  Application Example 4 The drawing method according to the application example further includes a medium thickness acquisition step of acquiring thickness information of the drawing medium, and the head distance adjustment step acquires the medium thickness acquisition step. It is preferable to adjust the distance between the nozzle surface and the outer peripheral surface in consideration of thickness information.

  According to the drawing method according to the application example, the thickness information of the drawing medium is acquired in the medium thickness acquisition step. In the head distance adjustment step, the distance between the nozzle surface and the outer peripheral surface is adjusted in consideration of the thickness information. The distance that the ejected liquid material flies is the distance from the nozzle surface to the drawing medium. The distance is a distance obtained by subtracting the thickness of the drawing medium from the distance between the nozzle surface and the outer peripheral surface. That is, the distance varies depending on the thickness of the drawing medium. In the head distance adjustment step, the distance between the nozzle surface and the outer peripheral surface is adjusted to an appropriate distance by adjusting the thickness information of the drawing medium in consideration of the difference in the thickness of the drawing medium. Can be maintained.

  Application Example 5 In the drawing method according to the application example, the head distance adjustment step calculates the outer diameter of the conveyance drum based on the temperature of the conveyance drum detected in the drum temperature detection step, and the nozzle A head distance calculating step for calculating a distance between a surface and the outer peripheral surface; and a position of the ejection head based on the distance between the nozzle surface and the outer peripheral surface calculated in the head distance calculating step. It is preferable to include a head position adjusting step of adjusting a distance between the nozzle surface and the outer peripheral surface by displacing.

  According to the drawing method according to the application example, in the head distance calculating step, first, the outer diameter of the transport drum is calculated based on the temperature of the transport drum. The distance between the nozzle surface and the outer peripheral surface can be calculated from the outer diameter of the transport drum and the positional relationship between the transport drum and the discharge head. In the head distance adjustment step, the distance between the nozzle surface and the outer peripheral surface is maintained at an appropriate distance by displacing the position of the ejection head based on the calculated distance so that the appropriate distance can be maintained. be able to.

  Application Example 6 In the drawing method according to the application example described above, temperature-dependent distance information that acquires temperature-dependent distance information indicating a correlation between the temperature of the transport drum and the distance between the nozzle surface and the outer peripheral surface. The head distance adjustment step is further based on the temperature-dependent distance information acquired in the temperature-dependent distance information acquisition step and the temperature of the transport drum detected in the drum temperature detection step. The head distance acquisition step for acquiring the distance between the nozzle surface and the outer peripheral surface, and the ejection based on the distance between the nozzle surface and the outer peripheral surface acquired in the head distance acquisition step It is preferable to include a head position adjusting step of adjusting a distance between the nozzle surface and the outer peripheral surface by displacing the head position.

  According to the drawing method according to the application example, in the temperature-dependent distance information acquisition step, temperature-dependent distance information indicating a correlation between the temperature of the transport drum and the distance between the nozzle surface and the outer peripheral surface is acquired. In the head distance acquisition step, the distance between the nozzle surface and the outer peripheral surface when adjustment is not performed can be obtained by comparing the temperature of the conveyance drum detected in the drum temperature detection step with the temperature-dependent distance information. . In the head distance adjustment step, the distance between the nozzle surface and the outer peripheral surface is maintained at an appropriate distance by displacing the position of the ejection head based on the obtained distance so that the appropriate distance can be maintained. be able to.

FIG. 3 is a front view schematically illustrating the configuration of a main part of the printer. (A) is an external appearance perspective view which shows the outline | summary of the single head body which comprises a discharge head. (B) is an explanatory view showing the arrangement of single head bodies in the ejection head. The front view which shows the structure of a drawing unit typically. FIG. 3 is an electrical configuration block diagram schematically illustrating an electrical configuration for controlling the printer. FIG. 3 is an explanatory diagram illustrating an electrical configuration for adjusting the platen gap and an outline of movement of each unit when the adjustment is performed.

  Hereinafter, an embodiment of a drawing apparatus according to the present invention will be described with reference to the drawings. In the present embodiment, the drawing apparatus is a printer that forms an image on a long sheet using an ultraviolet curable functional liquid. Note that in the drawings referred to in the following description, the vertical and horizontal scales of the members or portions may be expressed differently from the actual ones in order to make each configuration recognizable.

<Printer>
First, the overall configuration of the printer 1 will be described with reference to FIG. FIG. 1 is a front view schematically showing a configuration of a main part of the printer.
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. It is stretched. The route of the stretched sheet S is expressed as a route Pc. The sheet S is conveyed from the feeding shaft 20 to the winding shaft 40 along the path Pc. 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, and coated paper. The film system includes synthetic paper, PET (Polyethylene terephthalate), PP (Polypropylene) and the like. Schematically, the printer 1 includes a feeding unit 2 that feeds the sheet S from the feeding shaft 20, an image forming unit 3 that records an image on the sheet S that is fed from the feeding unit 2, and an image that is recorded by the image forming unit 3. And a winding unit 4 that winds the sheet S around the winding shaft 40. In the following description, of both surfaces of the sheet S, a surface on which an image is recorded is referred to as a front surface. The surface opposite to the front surface is referred to as the back surface. The vertical direction (vertical direction in FIG. 1) is the Z-axis direction, the axial direction of the take-up shaft 40 (direction perpendicular to the paper surface of FIG. 1) is the Y-axis direction, and the direction orthogonal to the Z-axis direction and the Y-axis direction is X. Expressed as the axial direction. The sheet S corresponds to a drawing medium.

  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 sheet S with the surface of the sheet S facing outward. When the feeding shaft 20 rotates clockwise in FIG. 1, the sheet S wound around the feeding shaft 20 is fed to the image forming unit 3 via the driven roller 21. The sheet S is wound around the feeding shaft 20 via a core tube (not shown) that is detachable from the feeding shaft 20. 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 attached to the feeding shaft 20 and the sheet S of the feeding shaft 20 can be replaced. Yes. The feeding shaft 20 rotates by receiving a driving force from a motor M connected to a base shaft (not shown).

  The image forming unit 3 forms an image on the sheet S by the drawing unit 5 disposed along the outer peripheral surface of the platen drum 30 while the sheet S fed from the feeding unit 2 is supported by the platen drum 30. Details of the drawing unit 5 will be described later. In the image forming 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 wound around the platen drum 30. Hung and supported. The functional liquid is ejected from the ejection head 55 provided in the drawing unit 5 toward the portion of the sheet S wound around the platen drum 30, and an image is formed by the functional liquid landed on the sheet S.

  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. Further, a nip roller 31 a that conveys the sheet S in cooperation with the front drive roller 31 is provided. The nip roller 31 a is in contact with the surface of the sheet S while being biased toward the front driving roller 31, and sandwiches the sheet S between the front driving 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). The platen drum 30 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 with the sheet S and rotating in accordance with the conveyance direction Ds of the sheet S. The platen drum 30 corresponds to the transport drum.

  The image forming unit 3 is provided with a driven roller 33 and a driven roller 34 that folds the sheet S on both sides of the winding part around the platen drum 30. The driven roller 33 wraps the surface of the sheet S between the front drive roller 31 and the platen drum 30 and folds the sheet S. 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. In this manner, by folding the sheet S on the upstream side and the downstream side in the transport direction Ds with respect to the platen drum 30, it is possible to ensure a long winding length of the sheet S around the platen drum 30.

  The rear drive roller 32 has a plurality of minute protrusions formed by thermal spraying on the outer peripheral surface, and winds the sheet S conveyed from the platen drum 30 via the driven roller 34 from the back surface side. The rear drive roller 32 conveys the sheet S to the winding unit 4 by rotating clockwise in FIG. Further, a nip roller 32 a that conveys the sheet S in cooperation with the rear drive roller 32 is provided. The nip roller 32 a 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. Thereby, the 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 image forming unit 3, in order to form a color image on the surface of the sheet S supported by the platen drum 30, the drawing unit 5 is provided with a plurality of ejection heads 55 corresponding to different colors. Each discharge head 55 is opposed to the surface of the sheet S wound around the platen drum 30 with a slight clearance, and discharges the corresponding color functional liquid by the ink jet method. A color image is formed on the surface of the sheet S as each ejection head 55 ejects the functional liquid onto the sheet S conveyed in the conveyance direction Ds. The functional liquid corresponds to a liquid material.

As the functional liquid, UV (Ultraviolet) ink (photocurable ink) that is cured by irradiating with ultraviolet rays (light) is used. The drawing unit 5 is provided with a UV lamp (not shown) in order to cure the ink and fix it on the sheet S. The drawing unit 5 is further provided with a temperature sensor 71 for detecting the temperature of the outer peripheral surface of the platen drum 30. UV ink (photo-curable ink) corresponds to a photo-curable liquid. A UV lamp (not shown) corresponds to a curing light source.
Further, in the image forming unit 3, a UV lamp 63 is provided on the downstream side of the drawing unit 5. The color image formed by the ejection head 55 can be fixed on the surface of the sheet S by the UV lamp and the UV lamp 63 provided in the drawing unit 5. Ultraviolet rays correspond to curing light. The UV lamp 63 corresponds to a curing light source.
As described above, in the image forming unit 3, the functional liquid is appropriately discharged and cured on the sheet S wound around the outer peripheral portion of the platen drum 30 to form a color image. 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. When the take-up shaft 40 rotates clockwise in FIG. 1, the sheet S conveyed from the rear drive roller 32 is taken up by the take-up shaft 40 via the driven roller 41. The sheet S is wound around the winding shaft 40 via a core tube (not shown) that is detachable from the winding shaft 40. When the sheet S wound around the winding shaft 40 is full, the sheet S can be removed together with the core tube. The winding shaft 40 rotates in response to a driving force from a motor M connected to a base shaft (not shown).

<Discharge head>
Next, the configuration of the ejection head 55 provided in the drawing unit 5 will be described with reference to FIG. FIG. 2 is an explanatory diagram schematically showing the configuration of the ejection head. FIG. 2A is an external perspective view showing an outline of a single head body constituting the ejection head, and FIG. 2B is an explanatory diagram showing an arrangement of single head bodies in the ejection head. The X-axis direction, Y-axis direction, and Z-axis direction shown in FIG. 2 are the same as the X-axis direction, Y-axis direction, or Z-axis direction shown in FIG. 1 when the discharge head 55 is mounted on the printer 1. Match.
As shown in FIG. 2A, the single head body 57 includes a nozzle substrate 16. The nozzle substrate 16 is formed with one row of nozzle rows 15A in which a large number of discharge nozzles 15 are arranged in a substantially straight line. The functional liquid is ejected as droplets from the ejection nozzle 15 and landed on the surface of the sheet S at the opposite position, thereby arranging the functional liquid at the position. An image is formed on the surface of the sheet S by the arranged functional liquid. The nozzle row 15 </ b> A extends in the Y-axis direction shown in FIG. 1 in a state where the discharge head 55 including the single head body 57 is mounted on the printer 1. In the nozzle row 15A, the discharge nozzles 15 are arranged at equal nozzle pitches. As the single head body 57, functional liquid droplets can be arranged at nozzle pitch intervals in the Y-axis direction. The surface of the nozzle substrate 16 corresponds to the nozzle surface.

  As shown in FIG. 2B, the ejection head 55 includes a head substrate 58 and seven single head bodies 57 mounted on the head substrate 58. The single head body 57 is fixed to the head substrate 58 via a head holding member (not shown). In the fixed single head body 57, the head body is loosely fitted in a hole (not shown) formed in the head substrate 58, and the nozzle substrate 16 is located at a position protruding from the surface of the head substrate 58. FIG. 2B is a view as seen from the nozzle substrate 16 side. The head substrate 58 is attached to a head frame (not shown).

The seven single head bodies 57 included in one discharge head 55 are arranged in the Y-axis direction with respect to the discharge nozzle 15 at the end of one single head body 57 of the single head bodies 57 adjacent to each other. The discharge nozzle 15 at the end of the single head body 57 is disposed at a relative position where it is shifted by one nozzle pitch. In the seven single head bodies 57 of the discharge head 55, if the positions of all the discharge nozzles 15 in the X-axis direction are the same, the discharge nozzles 15 are arranged at equal intervals of 1 nozzle pitch in the Y-axis direction. That is, at the same position in the transport direction of the sheet S, the droplets ejected from the ejection nozzles 15 constituting each nozzle row 15A of each single head body 57 are designed at regular intervals in the Y-axis direction. Land on a straight line side by side.
Since the single head bodies 57 overlap with each other in the Y-axis direction, they are arranged in a so-called staggered manner to form the ejection head 55.

<Drawing unit>
Next, the configuration of the drawing unit 5 will be described with reference to FIG. FIG. 3 is a front view schematically showing the configuration of the drawing unit. The X-axis direction, Y-axis direction, and Z-axis direction shown in FIG. 3 coincide with the X-axis direction, Y-axis direction, or Z-axis direction shown in FIG.
As shown in FIG. 3, the drawing unit 5 includes a head carriage 52, four ejection heads 55, four head separation / contact mechanisms 54, and a temperature sensor 71. As described above, the ejection head 55 includes seven single head bodies 57. Seven single head bodies 57 included in one discharge head 55 discharge the same functional liquid. The four discharge heads 55 provided in the drawing unit 5 discharge functional liquids for drawing yellow, cyan, magenta, or black, respectively. The discharge head 55 that discharges a functional liquid for drawing yellow is referred to as a Y discharge head 55Y. The ejection head 55 that ejects a functional liquid for drawing cyan is referred to as a C ejection head 55C. The ejection head 55 that ejects a functional liquid for drawing magenta is referred to as an M ejection head 55M. The discharge head 55 that discharges the functional liquid for drawing black is referred to as a K discharge head 55K.

  The Y discharge head 55Y, the C discharge head 55C, the M discharge head 55M, and the K discharge head 55K are arranged with the discharge nozzle 15 of the single head body 57 facing the outer peripheral surface of the platen drum 30 via the head separation / contact mechanism 54. It is held by the head carriage 52. The head separation / contact mechanism 54 is driven by a separation / contact mechanism motor 53 provided in the head separation / contact mechanism 54, and moves the ejection head 55 in a direction to separate / contact the outer peripheral surface of the platen drum 30. As described above, the nozzle row 15A included in each discharge head 55 extends in the Y-axis direction. The Y ejection head 55Y, the C ejection head 55C, the M ejection head 55M, and the K ejection head 55K are arranged in this order in the transport direction Ds. Each ejection head 55 is held by the head carriage 52 via the head separation / contact mechanism 54 in a state where the nozzle substrate 16 is substantially parallel to the tangent line on the X-axis / Z-axis plane of the outer peripheral surface of the platen drum 30. Yes. Further, each discharge head 55 is held by the head carriage 52 in a state in which the distances from all the discharge nozzles 15 included in one discharge head 55 to the outer peripheral surface of the platen drum 30 are substantially equal.

The Y discharge head 55Y is connected to the head attaching / detaching mechanism 54a, the C discharge head 55C is connected to the head attaching / detaching mechanism 54b, the M discharge head 55M is connected to the head attaching / detaching mechanism 54c, and the K discharge head 55K is connected to the head attaching / detaching mechanism 54d. The platen drum 30 is attached to the head carriage 52 so as to be movable with respect to the outer peripheral surface.
The separation mechanism motor 53 provided in the head separation mechanism 54a, the head separation mechanism 54b, the head separation mechanism 54c, and the head separation mechanism 54d is separated into the separation mechanism motor 53a, the separation mechanism motor 53b, and the separation mechanism. They are expressed as a motor 53c and a separation / connection mechanism motor 53d. The Y discharge head 55Y, the C discharge head 55C, the M discharge head 55M, and the K discharge head 55K are individually movable in the directions indicated by arrows a, b, c, or d in FIG. . The direction indicated by the arrow a, the arrow b, the arrow c, or the arrow d is a normal direction of the outer peripheral surface of the platen drum 30.
The Y discharge head 55Y, the C discharge head 55C, the M discharge head 55M, and the K discharge head 55K are moved in the normal direction of the outer peripheral surface with respect to the outer peripheral surface of the platen drum 30 by the head separation / contact mechanism 54. The distance (platen gap) between the nozzle substrate 16 and the outer peripheral surface of the platen drum 30 is maintained at an appropriate platen gap value. That is, the distance (head gap) between the nozzle substrate 16 and the sheet S supported on the outer peripheral surface of the platen drum 30 is maintained at an appropriate head gap value. The head separation / contact mechanism 54 corresponds to a head displacement device.
The head carriage 52 is supported by a carriage movement mechanism (not shown) so as to be movable in the Y-axis direction.

  The printer 1 includes a maintenance device for performing maintenance of the ejection head 55 provided in the drawing unit 5. The maintenance device is arranged at a position aligned with the platen drum 30 in the Y-axis direction. When carrying out maintenance work, the carriage unit moves the head carriage 52 in the Y-axis direction and moves the drawing unit 5 to a position facing the maintenance device. The Y ejection head 55Y, the C ejection head 55C, the M ejection head 55M, and the K ejection head 55K are moved by the head separation / contact mechanism 54a, the head separation / contact mechanism 54b, the head separation / contact mechanism 54c, and the head separation / contact mechanism 54d. Then, the maintenance device is positioned at an appropriate position for performing maintenance work. In this state, maintenance of the ejection head 55 provided in the drawing unit 5 is performed by the maintenance device.

  The temperature sensor 71 is arranged on the downstream side in the transport direction Ds of the sheet S of the K discharge head 55K so as to detect the temperature of the outer peripheral surface of the platen drum 30. The temperature sensor 71 is disposed at a position that does not overlap the sheet S supported by the platen drum 30 in the Y-axis direction. Therefore, even when the sheet S is wound around the platen drum 30 and drawing is performed, the temperature sensor 71 can detect the temperature of the portion of the outer peripheral surface of the platen drum 30 that is not covered with the sheet S. Thus, the temperature of the platen drum 30 can be detected. For example, a non-contact temperature sensor such as an infrared temperature sensor can be used as the temperature sensor 71. Alternatively, a contact temperature sensor such as a thermocouple or a thermistor thermometer can be used.

<Electrical configuration and control of printer>
Next, the electrical configuration for controlling the printer 1 and the control of the printer 1 will be described with reference to FIG. FIG. 4 is an electrical configuration block diagram schematically showing an electrical configuration for controlling the printer. 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. The host control unit 100 controls each unit of the host computer 10 and 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 110 and an operation unit 140 as an interface with an operator. The monitor 110 is composed of a liquid crystal display or the like. The operation unit 140 includes a keyboard, a mouse, and the like. In addition to the image to be printed, a menu screen is displayed on the monitor 110. The operator operates the operation unit 140 while checking the monitor 110 to open the print setting screen from the menu screen and set various print conditions such as the type of print medium, the size of the print medium, and the print quality. be able to. 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 110, and the operation unit 140 may be configured with the touch panel of the monitor 110.

  On the other hand, the printer 1 is provided with a printer control unit 200 that controls each unit of the printer 1 in response to a command from the host computer 10. The discharge head 55, the UV lamp 63, the separation / contact mechanism motor 53 of the head separation / contact mechanism 54, and each unit of the sheet conveyance system are controlled by the printer control unit 200.

The printer control unit 200 controls the ejection timing of the functional liquid of each ejection head 55 that forms a color image according to the conveyance of the sheet S. Specifically, the control of the functional liquid discharge timing is executed based on an output (detection value) of a drum encoder 30E that is attached to the rotation shaft of the platen drum 30 and detects the rotation position of the platen drum 30. Since the platen drum 30 is driven and rotated as the sheet S is conveyed, the conveyance position and conveyance amount of the sheet S can be grasped by referring to the output of the drum encoder 30E that detects the rotation position of the platen drum 30. it can. The printer control unit 200 generates a pts (print timing signal) signal from the output of the drum encoder 30E, and controls the ink discharge timing of each discharge head 55 based on the pts signal, thereby discharging each discharge head 55. A color image is formed by landing the ink on the target position of the sheet S to be conveyed.
The driving of the UV lamp 63 is also controlled by the printer control unit 200.

Further, the printer control unit 200 controls the distance (platen gap) between the nozzle substrate 16 and the outer peripheral surface of the platen drum 30. That is, the distance (head gap) between the nozzle substrate 16 and the sheet S supported by the platen drum 30 is controlled.
The printer control unit 200 acquires the temperature of the platen drum 30 detected by the temperature sensor 71. Based on the acquired temperature, the separation mechanism motor 53 of the head separation mechanism 54 is controlled to control the platen gap (head gap).
As described above, the head attaching / detaching mechanism 54a, the head attaching / detaching mechanism 54b, the head attaching / detaching mechanism 54c, and the head attaching / detaching mechanism 54d are respectively the attaching / detaching mechanism motor 53a, the attaching / detaching mechanism motor 53b, and the attaching / detaching mechanism motor 53c. Or a separation / connection mechanism motor 53d. The printer control unit 200 controls the separation / contact mechanism motor 53a, the separation / contact mechanism motor 53b, the separation / contact mechanism motor 53c, and the separation / contact mechanism motor 53d to control the Y ejection head 55Y, the C ejection head 55C, the M ejection head 55M, The platen gap (head gap) is controlled by moving the K discharge head 55K forward and backward in the normal direction of the outer peripheral surface of the platen drum 30.
The printer control unit 200 corresponds to a head distance adjustment unit.

  Further, the printer control unit 200 controls a function of controlling the conveyance of the sheet S described with reference to FIG. Of the members constituting the sheet conveying system, a motor is connected to each of the feeding shaft 20, the front driving roller 31, the rear driving roller 32, and the winding shaft 40. 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 20 </ b> M 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 20M to adjust the tension (feeding tension) of the sheet S from the feeding shaft 20 to the front drive roller 31. A tension sensor 21 </ b> T for detecting a feeding tension is attached to the driven roller 21 disposed between the feeding shaft 20 and the front drive roller 31. The tension sensor 21T can be configured by a load cell that detects a force received from the sheet S, for example. The printer control unit 200 adjusts the feeding tension of the sheet S by feedback control of the torque of the feeding motor 20M based on the detection result of the tension sensor 21T.

  At this time, the printer control unit 200 feeds the sheet S while adjusting the position in the width direction (Y-axis direction) of the sheet S supplied from the feeding shaft 20 to the front drive roller 31. The printer 1 is provided with a steering unit 7 that displaces the feeding shaft 20 and the driven roller 21 in the axial direction (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 drive roller 31. The edge sensor Se can be constituted by a distance sensor such as an ultrasonic sensor, for example. 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 controls and rotates the front drive motor 31M that drives the front drive roller 31 and the rear drive motor 32M that drives the rear drive roller 32. As a result, the sheet S fed from the feeding unit 2 passes through the image forming unit 3. At this time, torque control is executed for the front drive motor 31M, while speed control is executed for the rear drive motor 32M. That is, the printer control unit 200 adjusts the rotation speed of the rear drive motor 32M to be constant based on the encoder output of the rear drive motor 32M. Thus, the sheet S is conveyed at a constant speed by the rear drive roller 32.

  On the other hand, the printer control unit 200 adjusts the tension (process tension) of the sheet S from the front drive roller 31 to the rear drive roller 32 by controlling the torque of the front drive motor 31M. A tension sensor 33T that detects a process tension is attached to the driven roller 33 disposed between the front drive roller 31 and the platen drum 30 in the transport path Pc. The tension sensor 33T can be configured by a load cell that detects a force received from the sheet S, for example. The tension of the sheet S from the front drive roller 31 toward the platen drum 30 is detected by the tension sensor 33T. The printer control unit 200 adjusts the process tension of the sheet S by feedback controlling the torque of the front drive motor 31M based on the detection result of the tension sensor 33T.

  In this way, the tension of the sheet S is detected at the position of the driven roller 33 arranged with respect to the conveyance path Pc between the front drive roller 31 and the rear drive roller 32. And the torque of the front drive roller 31 is controlled based on this detection result. Thereby, a stable process tension can be applied to the sheet S from the front drive roller 31 to the rear drive roller 32. Then, an image is recorded on the surface of the sheet S supported by the platen drum 30 disposed with respect to the conveyance path Pc between the front drive roller 31 and the rear drive roller 32. Therefore, an image can be recorded on the sheet S with stable tension.

The sheet S on which the image is recorded by the image forming unit 3 is wound around the winding shaft 40 in the winding unit 4. At this time, the printer control unit 200 rotates the winding motor 40 </ b> M 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 40M to adjust the tension (winding tension) of the sheet S from the rear drive roller 32 to the winding shaft 40. A tension sensor 41T that detects a winding tension is attached to the driven roller 41 disposed between the rear drive roller 32 and the winding shaft 40. The tension sensor 41T can be configured by a load cell that detects a force received from the sheet S, for example.
The printer control unit 200 adjusts the winding tension of the sheet S by feedback controlling the torque of the winding motor 40M based on the detection result of the tension sensor 41T. Specifically, the printer control unit 200 decreases the winding tension in accordance with the increase in the diameter of the roll made of the sheet S wound around the winding shaft 40. Thus, the sheet S is controlled so that the pressure of the sheet S near the center of the roll becomes excessive and the sheet S is not damaged as the roll diameter increases.

<Adjustment of platen gap (head gap)>
Next, a process of adjusting the platen gap (head gap) to an appropriate value in response to a change in the temperature of the platen drum 30 will be described with reference to FIG. FIG. 5 is an explanatory diagram showing an electrical configuration for adjusting the platen gap and an outline of the movement of each unit when the adjustment is performed.
First, a configuration having a function of adjusting the platen gap to an appropriate value will be described. As described above, the drawing unit 5 includes the Y ejection head 55Y, the C ejection head 55C, the M ejection head 55M, and the K ejection head 55K including the nozzle substrate 16. The Y ejection head 55Y, the C ejection head 55C, the M ejection head 55M, and the K ejection head 55K are connected to the platen via the head separation / contact mechanism 54a, the head separation / contact mechanism 54b, the head separation / contact mechanism 54c, or the head separation / contact mechanism 54d. It is attached to the head carriage 52 so as to be movable with respect to the outer peripheral surface of the drum 30. The head attaching / detaching mechanism 54a, the head attaching / detaching mechanism 54b, the head attaching / detaching mechanism 54c, and the head attaching / detaching mechanism 54d are driven by the attaching / detaching mechanism motor 53a, the attaching / detaching mechanism motor 53b, the attaching / detaching mechanism motor 53c, or the attaching / detaching mechanism motor 53c. A contact mechanism motor 53d is provided. The Y ejection head 55Y, the C ejection head 55C, the M ejection head 55M, and the K ejection head 55K control the separation / contact mechanism motor 53a, the separation / contact mechanism motor 53b, the separation / contact mechanism motor 53c, or the separation / contact mechanism motor 53d. Thus, the platen drum 30 can be moved back and forth in the normal direction of the outer peripheral surface with respect to the outer peripheral surface of the platen drum 30.
The drawing unit 5 includes a temperature sensor 71. The temperature sensor 71 can detect the temperature of the platen drum 30.

The printer control unit 200 includes a separation / contact control unit 202, a calculation unit 204, and a storage unit 206. The storage unit 206 stores various information input from the host computer 10. The stored information includes, for example, information such as the coefficient of thermal expansion of the material constituting the platen drum 30 and the shape of the platen drum 30 for calculating the amount of thermal expansion of the platen drum 30, and the platen drum 30 and the discharge head. Information on the positional relationship with 55 and the like.
The calculation unit 204 is electrically connected to the separation / contact control unit 202, the storage unit 206, and the temperature sensor 71. The calculation unit 204 acquires the detected temperature of the platen drum 30 from the temperature sensor 71, and acquires various information for calculating the thermal expansion amount of the platen drum 30 from the storage unit 206. The expansion amount of the platen drum 30 is calculated from the acquired temperature and various information of the platen drum 30, and the position correction amount of the ejection head 55 for appropriately maintaining the platen gap is calculated.

  The separation / contact control unit 202 is electrically connected to the calculation unit 204, the head separation / contact mechanism 54a, the head separation / contact mechanism 54b, the head separation / contact mechanism 54c, and the head separation / contact mechanism 54d. The separation / contact control unit 202 acquires a position correction amount of the ejection head 55 for appropriately maintaining the platen gap calculated by the calculation unit 204 from the calculation unit 204. The separation / contact control unit 202 controls the head separation / contact mechanism 54a, the head separation / contact mechanism 54b, the head separation / contact mechanism 54c, and the head separation / contact mechanism 54d according to the acquired position correction amount, and discharges the Y ejection head 55Y, C ejection. The head 55C, the M discharge head 55M, and the K discharge head 55K are moved. More specifically, the separation / contact mechanism motor 53a, the separation / contact mechanism motor 53b, the separation / contact mechanism motor 53c, and the separation / contact mechanism motor 53d are controlled to move the ejection head 55. The calculation unit 204 and the separation / contact control unit 202 correspond to a head distance adjustment unit.

Next, the process of adjusting the platen gap to an appropriate value will be described.
First, information for calculating the amount of thermal expansion of the platen drum 30 is input via the host computer 10 and stored in the storage unit 206 in advance. At this time, the diameter of the outer peripheral surface 300 of the platen drum 30 when the temperature of the platen drum 30 is the reference temperature t0 is also stored in the storage unit 206.
Next, the temperature sensor 71 detects the drum temperature t 1 of the platen drum 30. This process corresponds to a drum temperature detection process.
The detected drum temperature t1 is transmitted to the calculation unit 204.

  Next, the calculation unit 204 calculates the thermal expansion amount d of the platen drum 30 corresponding to the difference between the reference temperature t0 and the drum temperature t1. From the thermal expansion amount d and the position (outer diameter) of the outer peripheral surface 300, the position of the outer peripheral surface 301 of the platen drum 30 at the drum temperature t1 is calculated. In the example shown in FIG. 5, the platen gap is smaller than the appropriate platen gap G0 by the thermal expansion amount d. Therefore, the position correction amount of the ejection head 55 for maintaining an appropriate platen gap G0 is the correction amount d. The correction amount d calculated by the calculation unit 204 is transmitted to the separation control unit 202. The step of calculating the platen gap by calculating the position of the outer peripheral surface 301 corresponds to the head distance calculation step. It also corresponds to a head distance adjustment step.

Next, the separation / contact control unit 202 controls the head separation / contact mechanism 54a, the head separation / contact mechanism 54b, the head separation / contact mechanism 54c, and the head separation / contact mechanism 54d based on the correction amount d transmitted from the calculation unit 204. By controlling, the Y ejection head 55Y, the C ejection head 55C, the M ejection head 55M, and the K ejection head 55K are moved. This process corresponds to a head position adjustment process. It also corresponds to a head distance adjustment step.
The Y discharge head 55Y, the C discharge head 55C, the M discharge head 55M, and the K discharge head 55K that have been moved by the correction amount d are replaced with the Y discharge head 550Y, the C discharge head 550C, the M discharge head 550M, and the K discharge head 550K. Is written. The nozzle substrate 160 (nozzle substrate 16) of the Y ejection head 550Y, the C ejection head 550C, the M ejection head 550M, and the K ejection head 550K is located at a distance G0 from the outer peripheral surface 301. The platen gap between the nozzle substrate 160 and the outer peripheral surface 301 is maintained at an appropriate platen gap G0.

  The appropriate platen gap G0 is a value that takes into account the thickness of the sheet S. For this reason, by maintaining the platen gap at an appropriate platen gap G0, the distance (head gap) between the nozzle substrate 16 and the surface of the sheet S supported on the outer peripheral surface of the platen drum 30 is also set to an appropriate value. Maintained. In order to cope with a plurality of types of sheets S having different thicknesses, the thickness information of the sheet S is also input when information for calculating the thermal expansion amount of the platen drum 30 is input. As an appropriate platen gap G0, for each sheet S, a value reflecting the input thickness of the sheet S is used. The step of inputting the thickness information of the sheet S corresponds to the medium thickness acquisition step.

Hereinafter, the effect by embodiment is described. According to the present embodiment, the following effects can be obtained.
(1) The distance between the nozzle substrate 16 of the discharge head 55 and the outer peripheral surface of the platen drum 30 by moving the discharge head 55 forward and backward with respect to the outer peripheral surface of the platen drum 30 by the head separation / contact mechanism 54. (Platen gap) can be adjusted. That is, the distance (head gap) between the nozzle substrate 16 and the surface of the sheet S supported on the outer peripheral surface of the platen drum 30 can be adjusted. The temperature sensor 71 detects the drum temperature t1 of the platen drum 30, and the calculation unit 204 calculates the thermal expansion amount d of the platen drum 30 corresponding to the difference between the reference temperature t0 and the drum temperature t1, thereby changing the temperature. The change in the diameter of the platen drum 30 due to the above can be obtained. The calculation unit 204 obtains the correction amount d from the amount of change in the diameter of the platen drum 30, and the separation / contact control unit 202 controls the head separation / contact mechanism 54 based on the correction amount d to move the ejection head 55. Thus, it is possible to correct the shift of the platen gap caused by the temperature change of the platen drum 30.

  (2) In order to correct the shift of the platen gap caused by the temperature change of the platen drum 30, the temperature sensor 71 detects the drum temperature t1 of the platen drum 30, and the calculation unit 204 detects the reference temperature t0 and the drum temperature t1. By calculating the thermal expansion amount d of the platen drum 30 corresponding to the difference, the change in the diameter of the platen drum 30 due to the temperature change is obtained. When using a device that directly measures the diameter of the platen drum 30 such as a displacement meter, it is necessary to accurately position the displacement meter and maintain the positioning accuracy. That is, a support device such as a displacement meter that is highly accurate and excellent in durability is required. Since the measuring means is the temperature sensor 71, a supporting device such as a displacement meter that is highly accurate and excellent in durability can be dispensed with.

(3) Since the measurement means is the temperature sensor 71, the expansion amount of the platen drum 30 can be obtained with high accuracy without requiring high measurement accuracy. The influence of the accuracy of the temperature sensor 71 on the calculated expansion amount is as follows. The platen drum 30 has a drum diameter of, for example, 500 mm, and is made of, for example, aluminum. The linear expansion coefficient of aluminum is 2.4 × 10 ⁻⁶ . When the accuracy of the temperature sensor 71 is ± 1 ° C., the calculated expansion amount error is ± 12 μm in calculation. The measurement accuracy of 1 ° C. is an accuracy realized by a general-purpose temperature sensor. Therefore, the expansion amount can be obtained with high accuracy using a general-purpose temperature sensor.

  (4) The temperature sensor 71 is disposed at a position that does not overlap the sheet S supported by the platen drum 30 in the Y-axis direction. Therefore, even when the sheet S is wound around the platen drum 30 and drawing is performed, the temperature sensor 71 can detect the temperature of the portion of the outer peripheral surface of the platen drum 30 that is not covered with the sheet S. Thus, the temperature of the platen drum 30 can be detected. Thereby, in parallel with the drawing of the image on the sheet S by the printer 1, it is possible to perform the adjustment for correcting the shift of the platen gap (head gap) due to the temperature change.

  As mentioned above, although preferred embodiment was described referring an accompanying drawing, suitable embodiment is not restricted to the said embodiment. The embodiment can of course be modified in various ways without departing from the scope, and can also be implemented as follows.

  (Modification 1) In the embodiment, the calculation unit 204 calculates the correction amount d by calculating the thermal expansion amount d of the platen drum 30 corresponding to the difference between the reference temperature t0 and the drum temperature t1. . However, in the head distance adjustment step, it is not essential to calculate the distance to move the ejection head in order to adjust the distance between the nozzle surface and the outer peripheral surface. A distance in which the ejection head is moved by using a table that shows a correlation between the temperature of the transport drum and the distance between the nozzle surface and the outer peripheral surface when the position of the ejection head is not corrected. You may ask for.

More specifically, first, in the printer 1, the relationship between the temperature of the platen drum 30 and the distance between the outer peripheral surface of the platen drum 30 and the nozzle substrate 16 of the discharge head 55 is measured in advance, and the temperature and the platen gap are measured. (Hereinafter referred to as “temperature PG information”). The temperature PG information corresponds to temperature-dependent distance information.
Next, temperature PG information is input via the host computer 10 and stored in the storage unit 206. This process corresponds to a temperature-dependent distance information acquisition process.
Next, the temperature sensor 71 detects the drum temperature t 1 of the platen drum 30. The detected drum temperature t1 is transmitted to the calculation unit 204.
Next, the calculation unit 204 obtains the value of the platen gap when the temperature of the platen drum 30 is the drum temperature t1 based on the temperature PG information. From this value and the appropriate platen gap G0, the position correction amount of the ejection head 55 for maintaining the appropriate platen gap G0 is obtained. This process corresponds to a head distance acquisition process. It also corresponds to a head distance adjustment step.
Next, the separation / contact control unit 202 controls the head separation / contact mechanism 54a, the head separation / contact mechanism 54b, the head separation / contact mechanism 54c, and the head separation / contact mechanism 54d based on the correction amount d transmitted from the calculation unit 204. By controlling, the Y ejection head 55Y, the C ejection head 55C, the M ejection head 55M, and the K ejection head 55K are moved. This process corresponds to a head position adjustment process. It also corresponds to a head distance adjustment step.

In this way, the platen gap between the nozzle substrate 160 and the outer peripheral surface 301 can be maintained at an appropriate platen gap G0.
The calculation unit 204 can obtain the value of the platen gap corresponding to the temperature of the platen drum 30 only by collating with the temperature PG information. For this reason, compared with the case where the amount of thermal expansion of the platen drum 30 is calculated from the temperature of the platen drum 30, the load on the calculation unit 204 can be reduced. Further, since the storage unit 206 only needs to store the temperature PG information, the load on the storage unit 206 can be reduced as compared with the case where information for calculating the thermal expansion amount of the platen drum 30 is stored. .

  (Modification 2) In the above embodiment, the functional liquid discharged from the discharge head 55 is a photocurable ink. However, it is not essential that the liquid is a photocurable liquid. The liquid material may be any liquid material as long as it can be discharged using the discharge head.

(Modification 3) In the above embodiment, the drawing unit 5 is provided with one head separation / contact mechanism 54 for one ejection head 55. However, in order to advance and retract the ejection head, it is not essential to provide a head displacement device for each ejection head. A configuration may be adopted in which a plurality of ejection heads are advanced and retracted by a single head displacement device. By providing one head displacement device for a plurality of ejection heads, the number of head displacement devices can be reduced, so that the drawing device can be simplified.
In addition, since each discharge head can be individually displaced by providing a single head displacement device for each discharge head, each discharge head can be advanced and retracted precisely. . Further, by making the advance / retreat direction by the head displacement device coincide with the discharge direction of the liquid material discharged from the discharge head, the angle of the flight direction of the liquid material with respect to the transport drum can be substantially set regardless of the position of the discharge head in the advance / retreat direction. Can be kept constant.

  (Modification 4) In the above embodiment, the head separation / contact mechanism 54 includes the separation / contact mechanism motor 53 as a drive source. However, it is not essential that the drive source of the head displacement device is a motor. The drive source of the head displacement device may be another power source such as an air cylinder or a hydraulic cylinder.

  (Modification 5) In the embodiment described above, the temperature sensor 71 is disposed downstream of the K discharge head 55K in the transport direction Ds of the sheet S so as to detect the temperature of the outer peripheral surface of the platen drum 30. . However, it is not essential to dispose the temperature sensor on the downstream side in the conveyance direction of the drawing medium with respect to the ejection head. The temperature sensor may be arranged on the upstream side in the conveyance direction of the drawing medium with respect to the ejection head.

  (Modification 6) In the above-described embodiment, the temperature sensor 71 is disposed downstream of the K ejection head 55K in the transport direction Ds of the sheet S so as to detect the temperature of the outer peripheral surface of the platen drum 30. . However, it is not essential to arrange the temperature sensor at a position where the temperature of the outer peripheral surface of the transport drum is detected. The portion where the temperature sensor detects the temperature may be the side surface of the transport drum. In addition, it is not essential to arrange the temperature sensor outside the transport drum. The temperature sensor may be disposed inside the conveyance drum, and the temperature of the wall constituting the conveyance drum may be detected from the inside.

  (Modification 7) In the above-described embodiment, the printer 1 includes the four ejection heads 55. However, the number of ejection heads included in the drawing apparatus is not limited to four. Any number of ejection heads may be provided in the drawing apparatus.

  (Modification 8) In the embodiment, the printer 1 uses the Y ejection head 55Y, the C ejection head 55C, the M ejection head 55M, and the K ejection head 55K to draw yellow, cyan, magenta, and black. I was prepared. However, the color tone drawn by the liquid discharged from the discharge head of the drawing apparatus is not limited to four colors of yellow, cyan, magenta, and black. The liquid discharged from the discharge head of the drawing apparatus may be a liquid that draws other colors such as light cyan and light magenta, or draws a background image or coating film such as white, metal, or colorless and transparent. For this purpose, it may be a liquid.

  (Modification 9) In the above embodiment, the ejection head 55 includes seven single head bodies 57. However, it is not essential that the discharge head has a configuration in which seven discharge heads such as the single head body 57 are combined. There may be any number of ejection heads such as the single head body 57 constituting the ejection head. The ejection head may be an ejection head such as one single head body 57. In the case where the ejection head is composed of one single head body 57, the single head body 57 corresponds to the ejection head.

  (Modification 10) In the above embodiment, the single head body 57 has one nozzle row of ejection nozzles. However, it is not essential that the number of nozzle rows provided in the ejection head such as the single head body 57 is one. Any number of nozzle rows may be provided in the ejection head such as the single head body 57.

  DESCRIPTION OF SYMBOLS 1 ... Printer, 2 ... Feeding part, 3 ... Image forming part, 4 ... Winding part, 5 ... Drawing unit, 10 ... Host computer, 15 ... Discharge nozzle, 16 ... Nozzle substrate, 30 ... Platen drum, 53 ... Separation / contact Mechanism motor, 53a, 53b, 53c, 53d ... separation / contact mechanism motor, 54 ... head separation / contact mechanism, 54a, 54b, 54c, 54d ... head separation / contact mechanism, 55 ... discharge head, 55C ... C discharge head, 55K ... K Discharge head, 55M ... M discharge head, 55Y ... Y discharge head, 57 ... single head body, 63 ... UV lamp, 71 ... temperature sensor, 100 ... host control unit, 160 ... nozzle substrate, 200 ... printer control unit, 202 ... Separation / contact control unit, 204 ... calculation unit, 206 ... storage unit, 300 ... outer peripheral surface, 301 ... outer peripheral surface, 550C ... C discharge head, 550K ... K discharge head, 50M ... M discharge head, 550Y ... Y discharge head.

Claims (6)

A transport drum for sending the drawing medium in close contact with the outer peripheral surface;
An ejection head provided with an ejection nozzle for ejecting a liquid material, the ejection surface disposed at a position where the nozzle surface faces the outer peripheral surface;
A head displacement device for moving the ejection head back and forth in the normal direction of the outer peripheral surface;
A temperature sensor for detecting the temperature of the transport drum;
A storage unit that stores information used to calculate the thermal expansion amount of the transport drum;
A calculation unit that calculates the thermal expansion amount of the transport drum using the temperature of the transport drum detected by the temperature sensor and information used to calculate the thermal expansion amount;
A head distance adjusting unit that controls the head displacement device based on the thermal expansion amount of the warm transfer drum and adjusts the distance between the nozzle surface and the outer peripheral surface;
A drawing apparatus characterized by that. The liquid material is a photocurable liquid material,
A curing light source for emitting curing light;
The drawing apparatus according to claim 1, wherein: A transport drum that feeds a drawing medium in close contact with the outer peripheral surface, a nozzle surface in which a discharge nozzle for discharging a liquid material is opened, and a discharge head disposed at a position where the nozzle surface faces the outer peripheral surface; A drawing method for drawing an image on the drawing medium using
A drum temperature detecting step for detecting the temperature of the transport drum;
A conveyance drum thermal expansion amount calculating step of calculating a thermal expansion amount of the conveyance drum based on the temperature of the conveyance drum detected in the drum temperature detection step;
A head distance adjustment step of adjusting a distance between the nozzle surface and the outer peripheral surface based on the thermal expansion amount of the transport drum calculated in the drum thermal expansion amount calculation step .
A drawing method characterized by that. A medium thickness obtaining step for obtaining thickness information of the drawing medium;
In the head distance adjustment step, the distance between the nozzle surface and the outer peripheral surface is adjusted in consideration of the thickness information acquired in the medium thickness acquisition step.
The drawing method according to claim 3, wherein: A transport drum that feeds a drawing medium in close contact with the outer peripheral surface, a nozzle surface in which a discharge nozzle for discharging a liquid material is opened, and a discharge head disposed at a position where the nozzle surface faces the outer peripheral surface; A drawing method for drawing an image on the drawing medium using
A drum temperature detecting step for detecting the temperature of the transport drum;
A head distance adjusting step of adjusting a distance between the nozzle surface and the outer peripheral surface based on the temperature of the transport drum detected in the drum temperature detecting step;
Have
The head distance adjustment step includes
A head distance calculating step of calculating an outer diameter of the conveying drum based on the temperature of the conveying drum detected in the drum temperature detecting step, and calculating a distance between the nozzle surface and the outer peripheral surface;
Based on the distance between the nozzle surface and the outer peripheral surface calculated in the head distance calculating step, the distance between the nozzle surface and the outer peripheral surface is adjusted by displacing the position of the ejection head. A head position adjusting step.
A drawing method characterized by that. A transport drum that feeds a drawing medium in close contact with the outer peripheral surface, a nozzle surface in which a discharge nozzle for discharging a liquid material is opened, and a discharge head disposed at a position where the nozzle surface faces the outer peripheral surface; A drawing method for drawing an image on the drawing medium using
A drum temperature detecting step for detecting the temperature of the transport drum;
A head distance adjusting step of adjusting a distance between the nozzle surface and the outer peripheral surface based on the temperature of the transport drum detected in the drum temperature detecting step;
A temperature-dependent distance information acquisition step of acquiring temperature-dependent distance information indicating a correlation between the temperature of the transport drum and the distance between the nozzle surface and the outer peripheral surface;
Have
The head distance adjustment step includes
The distance between the nozzle surface and the outer peripheral surface based on the temperature-dependent distance information acquired in the temperature-dependent distance information acquisition step and the temperature of the transport drum detected in the drum temperature detection step A head distance acquisition step of acquiring
The distance between the nozzle surface and the outer peripheral surface is adjusted by displacing the position of the ejection head based on the distance between the nozzle surface and the outer peripheral surface acquired in the head distance acquisition step. A head position adjusting step.
A drawing method characterized by that.

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