JP2011126082A - Image plotting device, and drive control method of image plotting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image plotting device capable of performing an image plotting operation by constantly maintaining an adequate gap. <P>SOLUTION: This image plotting device includes a medium conveyance mechanism 41 that has a rotary drum 61 for conveying a recording medium A in intimate contact with its outer circumferential surface 71a, thereby conveys the recording medium A along a printing conveyance path L2 following the outer circumferential surface 71a; a print head 76 that faces the conveyed recording medium A and performs printing on the recording medium A; a Z-axis moving mechanism 84 that moves the print head 76 back and forth in a direction of the normal line of the outer circumferential surface 71a so as to adjust the gap between a nozzle face 91 of the print head 76 and a recording face A1 of the recording medium A; gap measurement means 96, 121, 124 that face the outer circumferential surface 71a so as to measure the gap; and a control means 124 that controls the Z-axis moving mechanism 84 based on the measurement result so as to make the gap an adequate value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a drawing apparatus that performs a recording process on a recording medium such as paper or film, and a drive control method for the drawing apparatus.

  Conventionally, as this type of drawing apparatus, a medium feeding means for feeding a recording medium along an arc-shaped feeding path that follows the outer circumferential surface by a drum that feeds the recording medium in close contact with the outer circumferential surface, and arranged along the feeding path. There is known a medium recording unit that includes a plurality of head units that perform recording processing on a recording medium (see Patent Document 1). Each head unit is equipped with a plurality of ink jet heads facing the recording medium.

JP 2008-74051 A

By the way, the drum that becomes the platen is slightly deformed with respect to the perfect circle due to the roughness of the outer peripheral surface in terms of manufacturing accuracy (distortion, undulation, uneven thickness, etc.) and deformation due to thermal expansion. End up.
For this reason, in the above drawing apparatus, the gap (gap amount) between the nozzle surface of the inkjet head and the recording surface of the recording medium varies due to the recording medium feeding operation (rotational phase of the drum), and the drawing process is performed with high accuracy. There was a problem that could not be done. For example, when the gap is wider than usual, the inkjet head discharges the droplets, and the time until the droplets land on the recording medium becomes long, so the recording medium is sent in the meantime, The landing position will shift.

  An object of the present invention is to provide a drawing apparatus and a driving control method for the drawing apparatus that can always perform drawing processing with an appropriate gap.

  The drawing apparatus of the present invention 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 sent to the recording medium. An inkjet head for printing on a medium, a gap adjusting means for adjusting the gap between the nozzle surface of the inkjet head and the recording surface of the recording medium by moving the inkjet head back and forth in the normal direction of the outer circumferential surface, and the outer circumferential surface And a control means for controlling the gap adjusting means so that the gap becomes an appropriate value based on the measurement result of the gap measuring means.

  According to this configuration, the gap measurement unit measures the gap between the inkjet head and the recording surface, and the gap adjustment unit adjusts the gap so that it has an appropriate value. Since gap adjustment can be performed following the shape, drawing processing can always be performed with an appropriate gap. Therefore, the drawing process can be performed with high accuracy. As the gap measuring means, an ultrasonic type, a laser type (photosensor type), a contact type, and eventually a magnetic sensor type may be used.

  In this case, it is preferable that the rotating body is made of a dielectric, and the gap measuring means is made of a magnetic sensor that measures an eddy current generated between the rotating body and the rotating body.

  According to this configuration, since the gap measurement can be performed in a non-contact manner, the outer peripheral surface of the rotating body is not damaged. Further, unlike the case where the gap measurement is performed by the optical sensor, the gap measurement can be easily and accurately performed even if the outer peripheral surface shape is not stable.

  Another drawing apparatus of the present invention is directed to a medium feeding means for feeding a recording medium along a feeding path following 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 to be sent. An inkjet head that prints on a recording medium; and a gap adjusting unit that adjusts a gap between the nozzle surface of the inkjet head and the recording surface of the recording medium by moving the inkjet head back and forth in the normal direction of the outer peripheral surface; Control means for controlling the medium feeding means, the ink jet head, and the gap adjusting means, and the control means is defined by the correlation between the recording medium feed amount and the gap-by-gap change amount in one rotation of the rotary drum. The gap adjusting means is controlled so that the gap becomes an appropriate value based on the control table of the gap cycle change.

  The drawing apparatus drive control method according to the present invention is a drawing apparatus drive control method in which the gap between the nozzle surface of the inkjet head and the recording surface of the recording medium that is printed and fed relative to the inkjet head changes periodically. Then, based on the periodic change acquisition step of acquiring the periodic change of the gap, which is defined by the correlation between the feeding amount of the recording medium and the amount of change of the gap in one cycle, and the acquired periodic change, And a gap correction step for correcting the gap so as to be an appropriate value.

  According to this configuration, the gap adjustment can be performed following the shape of the outer peripheral surface of the rotating body by adjusting the gap so that the gap becomes an appropriate value based on the periodic change of the gap. The drawing process can always be performed with an appropriate gap. In addition, since the gap adjustment is performed based on the correlation between the feed amount in one cycle (one rotation) and the amount of change in the gap, the gap adjustment can be easily performed only by performing the gap measurement for one cycle in advance. Can do. Note that the gap measurement for one period may be performed only once at the start of driving of the drawing apparatus or at the start of work, or in addition to the measurement at the start of driving or at the start of work in order to cope with changes over time. A configuration may be adopted in which re-measurement is performed periodically during driving or work.

It is a front view of the ink jet device concerning an embodiment. It is a back surface perspective view of an apparatus main body. It is side sectional drawing of an apparatus main body. It is a perspective view of a carriage unit. It is sectional drawing around a head unit. It is a perspective view of a print head. It is a perspective view of a head unit. It is a perspective view of a pinning unit. It is the perspective view which showed the maintenance unit at the time of a maintenance (a) and a printing process (b). It is the front view (a) and sectional view (b) which showed the carriage unit and maintenance unit at the time of maintenance. It is the figure which showed the control structure of gap adjustment operation | movement. It is the figure which showed the control structure of the gap adjustment operation in 2nd Embodiment. It is the figure which showed the control structure of the gap adjustment operation in 3rd Embodiment.

  Hereinafter, an inkjet apparatus (drawing apparatus) according to an embodiment of the present invention will be described with reference to the accompanying drawings. This ink jet apparatus is a center drum type recording apparatus in which a plurality of ink jet heads are arranged in the circumferential direction, and printing is performed on a long recording medium supplied reel-to-reel using UV ink (ultraviolet curable ink). carry out. The recording medium is, for example, a sheet-like material such as a label film or paper, and has various widths and thicknesses to be printed. In the following description, the direction penetrating the paper surface in FIG. 1 is front and rear, the front side is “front”, and the back side is “rear”. Specifically, the extending direction of the rotating shaft (drum shaft 62) of the rotating drum 61 (described later) is the front and rear, the direction from the drum motor 64 (described later) toward the rotating drum 61 is the front direction (front side), and the rotating drum 61 A direction toward the drum motor 64 is a back direction (back side). In the medium feeding path L of the recording medium A, the medium supply device 6 side described later is referred to as “upstream side”, and the medium recovery device 7 side described later is referred to as “downstream side”.

  As shown in the overall view of FIG. 1, an inkjet apparatus 1 includes a center drum type apparatus main body 2 that performs printing on a recording medium A by an inkjet method, a recording medium A that is supplied with the recording medium A and printed. A reel-to-reel medium supply / recovery device 3 for collecting A and a control device (not shown) for overall control of these components are provided. The medium supply / collection apparatus 3 includes a medium supply apparatus 6 that supplies the recording medium A to the apparatus main body 2 and a medium recovery apparatus 7 that recovers the recording medium A from the apparatus main body 2. On the other hand, the medium feed path L of the recording medium A configured in the apparatus main body 2 and the medium supply / collection apparatus 3 is close to the supply feed path L1 from the medium supply apparatus 6 to the apparatus main body 2 and the circle configured in the apparatus main body 2. An arc-shaped print feed path (feed path) L2 and a recovery feed path L3 from the apparatus main body 2 to the medium recovery apparatus 7 are provided.

  The recording medium A supplied from the medium supply device 6 through the supply feed path L1 is fed along the print feed path L2 in the apparatus main body 2, and is used for printing in this portion. In addition, the recording medium A that has been printed is collected by the medium collection device 7 through the collection feeding path L3.

  The medium supply device 6 is disposed on the downstream side of the supply reel 11, a supply reel 11 for supplying the recording medium A wound in a roll shape, a supply motor (not shown) for supplying and rotating the supply reel 11, and a recording medium. A forward tension unit 13 that applies a forward tension to A, and a steering unit 14 that is disposed downstream of the forward tension unit 13 and feeds the recording medium A into the apparatus main body 2 while positioning the recording medium A in the width direction. Further, the supply reel 11 and the supply motor are supported by the paper supply unit frame 15 and constitute an integral paper supply unit 16. Further, the forward tension unit 13 is supported by the forward tension frame 17 and unitized.

  When the feeding motor is driven in synchronization with the apparatus main body 2 by the control device, the recording medium A is fed from the feeding reel 11. The fed recording medium A is fed along the feed feed path L1 while being given a predetermined tension by the forward tension unit 13, and finally the apparatus main body 2 while correcting the position in the width direction by the steering unit 14. Is sent to. Note that the steering unit 14 of the present embodiment is configured to send the recording medium A to the apparatus main body 2 with reference to one (back side) width end of the recording medium A. Accordingly, when the recording medium A having a different width is introduced, the width end on one side (the back side) is also the reference. However, it is also possible to introduce the recording medium A using the center in the width direction as a reference (center reference).

  The medium recovery device 7 includes a winding reel 21 that winds the printed recording medium A in a roll shape, a winding motor (not shown) that winds and rotates the winding reel 21, and an upstream side of the winding reel 21. And a back tension unit 23 that applies back tension to the recording medium A, and a recording medium A that is disposed upstream of the back tension unit 23 and is sent out from the apparatus main body 2 is sent in a U-turn. , And a return unit 25 for changing the route of the collection and feeding route L3. Also in this case, the take-up reel 21 and the take-up motor are supported by the paper discharge unit frame 26 and constitute an integral paper discharge unit 27. The back tension unit 23 is supported by the back tension frame 28 and unitized. Furthermore, a UV irradiation unit 44 of the apparatus main body 2 to be described later is disposed between the apparatus main body 2 and the folding unit 25 so as to face the recovery feed path L3.

  When the control device drives the take-up motor in synchronization with the apparatus main body 2, the recording medium A is fed out from the apparatus main body 2 while being given a predetermined tension by the back tension unit 23, and along the recovery feed path L 3. Will be sent. The recording medium A sent out from the apparatus main body 2 first passes through the UV irradiation unit 44. In this passing process, the UV ink is cured. Subsequently, the recording medium A that has been U-turned by the folding unit 25 is wound around the take-up reel 21 via the back tension unit 23. Note that the recording medium A taken up on the take-up reel 21 is introduced into a separate process apparatus and cut as a label or half-cut on the label portion.

  As shown in FIGS. 1 and 2, the apparatus main body 2 includes a large-diameter rotating drum 61, and a medium feeding mechanism (medium feeding means) 41 that feeds the recording medium A along the print feeding path L <b> 2. A plurality of print heads (inkjet heads) 76 that correspond to the plurality of carriage units 42 that are arranged radially with respect to the rotary drum 61 so as to face the print feed path L2, and the back surface thereof. A plurality of maintenance units 43 arranged on the side, and a UV irradiation unit 44 for main curing that cures the UV ink of the recording medium A, facing the recovery feeding path L3. The apparatus body 2 is entirely covered with a chamber (not shown). The plurality of carriage units 42 are units for the colors of the UV ink to be supplied, and constitute a printing unit 48 as a whole. In FIG. 1, the internal devices (head unit 83 and head control board module) are omitted from each carriage unit 42, and in FIG. 2, the internal devices (unit main body) are omitted from each maintenance unit 43. It is described as.

  As shown in FIGS. 2 and 3, the apparatus frame 46 includes a base frame 51 serving as a machine base, a main frame 52 erected on the rear half of the base frame 51, and a plate-like shape provided widely on the front surface of the main frame 52. And a chamber frame 54 disposed at the front portion of the main frame 52 with the subframe 53 interposed therebetween.

  The main frame 52 is formed by assembling a channel material in a square shape, supports various components via the subframe 53, and supports the medium feeding mechanism 41 having the rotary drum 61 as a main component. The subframe 53 is formed of a thick rectangular stainless steel plate or the like, and supports a plurality of carriage units 42 (see FIG. 1) and a UV irradiation unit 44 (see FIG. 1) in a cantilever manner on the front side, On the side (rear side), a plurality of maintenance units 43 and the like are supported in a cantilever manner. The chamber frame 54 is configured by assembling a channel material in a square shape, and is formed so as to cover the constituent device at the front portion of the main frame 52. Walls (not shown) are respectively attached to the surfaces constituting the main frame 52 and the chamber frame 54, and these constitute a chamber that covers the entire apparatus main body 2. That is, the apparatus main body 2 manages the temperature and cleanliness inside the chamber by this chamber. A predetermined gap is provided between the chamber frame 54 and the base frame 51, and the recording medium A is fed and discharged in this gap.

  The medium feeding mechanism 41 is composed of a rotating drum (rotating body) 61 formed in the shape of a sideways crown, a bearing 63 that can rotatably support the rotating drum 61 via a drum shaft 62, and the rotating drum 61. A drum motor 64 that rotates at a low speed in the direction, and a belt drive power transmission mechanism 65 interposed between the drum shaft 62 and the drum motor 64. The drum motor 64 is composed of, for example, a servo motor, and rotates the rotary drum 61 so that the peripheral speed (printing speed) on the outer peripheral surface 71a of the rotary drum 61 is constant.

  The rotary drum 61 includes a cylindrical drum body 71 and a disk portion 72 that covers the rear end of the drum body 71, and is made of a light metal such as aluminum. The drum main body 71 and the disk part 72 may be integrally molded, or may be formed by joining separately formed ones. The drum body 71 has a width corresponding to the maximum width of the recording medium A, and the outer peripheral surface 71a is baked to prevent slipping. The recording medium A is fed in close contact with the outer peripheral surface 71a of the non-slip processed drum body 71 and draws a circle (arc) by the rotating drum body 71. That is, the recording medium A sent from the medium supply device 6 is sent along the arc-shaped print feed path L2 that follows the outer peripheral surface 71a by the rotary drum 61. Then, printing is performed on the recording medium A by appropriately driving the printing unit 48 in synchronism with this feeding.

  As described above, the printing unit 48 includes the plurality of carriage units 42 arranged radially with respect to the rotary drum 61 (see FIG. 1). The plurality of carriage units 42 are ink color units, and are arranged in the order of cyan (C), magenta (M), yellow (Y), and black (Bk) from the start side to the end side of the print feed path L2. Thus, they are arranged at substantially equal intervals in the circumferential direction. As will be described in detail later, each carriage unit 42 has a plurality of print heads 76 mounted thereon, and the plurality of print heads 76 constitute a head 77 (line head) corresponding to the recording medium A having the maximum width. . For this reason, the heads 77 of the respective colors sequentially face the recording medium A that is printed and fed along the print feeding path L2, and desired color printing based on the print data is performed on the recording medium A.

  As shown in FIGS. 4 and 5, each carriage unit 42 is slidable on the carriage base 81 in the normal direction of the carriage base 81 fixed to the sub-frame 53 and the outer peripheral surface 71 a of the rotary drum 61. A box-shaped frame type carriage 82 supported, a head unit 83 mounted on the carriage 82 and mounted with a plurality of print heads 76, and the head unit 83 via the carriage 82 in the normal direction (rotation) of the print feed path L2. A Z-axis moving mechanism (gap adjusting means) 84 that advances and retreats in the normal direction of the outer peripheral surface 71 a of the drum 61, and a head control board module that is mounted on the carriage 82 on the back side and applies ejection waveforms to the plurality of print heads 76. (Not shown). Each carriage unit 42 is mounted on the carriage 82 and is supported on one outer surface of the carriage 82 via a pinning unit 86 for temporarily curing the UV ink of the recording medium A and a support fitting, and a plurality of print heads 76. And a sub-tank unit (not shown) for supplying UV ink.

  Each Z-axis moving mechanism 84 uses a pulse motor and moves each head unit 83 forward and backward in the normal direction of the outer peripheral surface 71 a of the rotary drum 61 via each carriage 82. Each Z-axis moving mechanism 84 of the embodiment records the head unit 83 and a gap adjustment that adjusts the gap between the nozzle surfaces 91 of the plurality of print heads 76 and the recording surface A1 of the recording medium A in each head unit 83. It has two functions of unit movement that moves between the position and the maintenance target position. In the gap adjustment, the gap is adjusted by moving the head unit 83 back and forth based on the detection result of the distance detection sensor 96 described later. On the other hand, in the unit movement, the head unit 83 is moved forward and backward to move between a recording position facing the print feed path L2 (recording medium A) and a maintenance position facing a unit main body at a maintenance position described later. That is, each Z-axis moving mechanism 84 moves the head unit 83 to the recording position during the printing process by each head unit 83 and appropriately adjusts the gap based on the detection result of the distance detection sensor 96. On the other hand, during maintenance, each head unit 83 is moved to the maintenance position. Here, although the Z-axis moving mechanism 84 is configured to use a pulse motor, it may be configured to use a servo motor or an induction motor with an encoder.

  The UV ink of the embodiment has a high temperature dependency (viscosity decreases as the temperature increases). Therefore, although not shown in the drawing, the sub tank unit, the plurality of print heads 76, and the ink flow paths (main tube, manifold, individual tube) from the sub tank unit to the plurality of print heads 76 are covered with a heater. . For example, the UV ink is heated to about 40 ° C. and discharged.

As shown in FIG. 6, each print head 76 is composed of a 2-inch inkjet head, and has two nozzle rows 93 composed of a plurality of ejection nozzles 92 parallel to each other on its nozzle surface 91. Yes. In this case, the two nozzle rows 93 are arranged with a 1/2 nozzle pitch position shift in the nozzle row direction.
On the other hand, as shown in FIGS. 5 and 7, the head unit 83 is detachably attached to the carriage 82 from the front. The head unit 83 is supported by the head plate 94, a pair of sub-plates 95 that are supported by the head plate 94, and are connected in a mountain shape so as to be parallel to the tangent to the rotary drum 61, and the pair of sub-plates 95. Distance detection for detecting the distance to the outer peripheral surface 71a of the rotary drum 61 while being supported by the head plate 94 and a plurality of print heads 76 (7 + 7 in the embodiment) mounted in half Sensor 96 (see FIG. 11).

  In this case, the plurality of print heads 76 (seven) mounted on each sub-plate 95 are all arranged in a staggered manner in the front-rear direction with the nozzle row 93 facing the front-rear direction. In addition, the plurality of print heads 76 mounted on one sub-plate 95 and the plurality of print heads 76 mounted on the other sub-plate 95 are displaced by 1/4 nozzle pitch position in the front-rear direction (nozzle row direction). Arranged. Accordingly, the head 77 as a line head extending in the front-rear direction (the width direction of the recording medium A) by all the print heads 76 mounted on the head plate 94, that is, the 1/4 nozzle corresponding to the recording medium A having the maximum width. A pitch head 77 is formed. Thereby, high-resolution printing becomes possible.

  The distance detection sensor 96 faces the print feed path L2, and detects the distance from the distance detection sensor 96 to the outer peripheral surface 71a of the rotary drum 61. The distance detection sensor 96 is a so-called eddy current type magnetic sensor. That is, the drum body 71 of the rotating drum 61 is made of a dielectric, and the distance detection sensor 96 generates a high-frequency magnetic field with the outer peripheral surface 71a of the rotating drum main body 71, and accordingly, the outer peripheral surface. The eddy current generated between 71a and 71a is measured to detect the distance to the outer peripheral surface 71a. Thus, the distance detection sensor 96 can detect the height in the radial direction on the outer peripheral surface 71a at the position where the distance detection sensor 96 faces. Although details will be described later, based on the detection result, the thickness of the recording medium A, and the positional relationship between the distance detection sensor 96 and the nozzle surface 91 of the print head 76, the nozzle surface 91 of the print head 76 and the recording medium. A gap (separation distance) between A and the recording surface A1 is calculated (measured). The distance detection sensor 96 may be disposed at an intermediate position in the medium feeding direction of the head plate 94, or may be disposed at an upstream position in consideration of a time lag due to distance detection and gap adjustment. Further, it may be disposed at an intermediate position in the front-rear direction (perpendicular to the medium feeding direction) or may be disposed at an end in the front-rear direction.

  As shown in FIG. 8, the pinning unit 86 includes a temporary curing UV lamp 98 that temporarily cures the UV ink of the recording medium A, and a duct-connected mist suction port 99 attached to the temporary curing UV lamp 98. ing. The pre-curing UV lamp (lamp array) 98 and the mist suction port (slit suction port) 99 extend in parallel with each other in the front-rear direction, and have substantially the same length and the same length in the front-rear direction with respect to the head 77 described above. Arranged in position. Further, the plurality of print heads 76 (head 77), the mist suction port 99, and the temporary curing UV lamp 98 are arranged in this order in the feeding direction of the recording medium A, and the UV ink discharged from the print head 76 is disposed. The mist is sucked through the mist suction port 99, and the UV ink landed on the recording medium A is temporarily cured by the temporary curing UV lamp 98. As a result, it is possible to cure the UV ink to such an extent that mist adhesion to the temporary curing UV lamp 98 is prevented and color mixing does not occur. Note that the order of the ink colors in the plurality of carriage units 42 is the order in which the UV inks for each color are hard to be cured.

  As shown in FIG. 2, each maintenance unit 43 is disposed on the extension in the front-rear direction of the corresponding carriage unit 42 with the subframe 53 interposed therebetween. As shown in FIGS. 9 and 10, the maintenance unit 43 includes a unit main body (not shown) that performs maintenance while facing the nozzle surfaces 91 of the plurality of print heads 76, a maintenance carriage 102 on which the unit main bodies are mounted, A maintenance moving mechanism 103 that moves the unit main body in the front-rear direction between the home position and the maintenance position via the maintenance carriage 102 is provided. When performing maintenance such as discard discharge (flushing) or suction of the print head 76, the unit main body moves to the front maintenance position and faces the print head 76 (see FIGS. 9A and 10). When the printing process is being performed on the recording medium A, the unit main body stands by at the rear home position (see FIG. 9B). As described above, the head unit 83 (carriage 82) is moved to the recording position on the inner side in the normal direction by the Z-axis moving mechanism 84 during the printing process, and is moved to the outer side in the normal direction by the Z-axis moving mechanism 84 at the time of maintenance. Since the unit moves to the maintenance position, the head unit 83 and the unit main body are positioned in series in the front and back so that the unit main body faces the head unit 83 during the printing process, and during the maintenance, the head unit 83 and the unit main body are connected to the rotating drum. 61 parallel to the normal direction.

  The unit main body includes, for example, a wiping mechanism for wiping the nozzle surface 91 of the print head 76, and a suction mechanism for sealing the nozzle surface 91, receiving discarded discharge, and nozzle suction. The maintenance moving mechanism 103 for moving the unit main body includes a bracket frame 113 fixed to the subframe 53 in a cantilever state, a pair of guide rails 114 passed between the bracket frame 113 and the carriage unit 42, and a pair of guide rails. 114 and an air-driven rotor actuator 117 that moves the maintenance carriage 102 in the front-rear direction along 114. Note that a maintenance opening 53a for allowing the maintenance carriage 102 to pass therethrough is formed in the subframe 53 (see FIG. 2).

  As shown in FIG. 1, the UV irradiation unit 44 is configured by a UV lamp, and faces the recording medium A on the recovery feeding path L3 from the lower side (printing surface side of the recording medium A), and reaches the recording medium A. The cured UV ink is fully cured. The UV irradiation unit 44 is equipped with a UV lamp and a suction fan for cooling the recording medium A.

  Here, the gap adjusting operation of the head unit 83 will be described with reference to FIG. FIG. 11 is a diagram illustrating a control configuration around the gap adjustment operation in the inkjet apparatus 1. As shown in FIG. 11, the inkjet apparatus 1 includes a plurality of sensor amplifiers 121 corresponding to a plurality of distance detection sensors 96 and a plurality of Z corresponding to a plurality of Z-axis moving mechanisms 84 as a control system around the gap adjustment operation. An axis motor driver 122, a plurality of pulse generators 123 corresponding to the plurality of Z axis motor drivers 122, and a robot controller 124 for controlling them are provided. That is, the ink jet apparatus 1 includes a sensor amplifier 121, a Z-axis motor driver 122, and a pulse generator 123 for each head unit 83. The robot controller 124 is connected to the above-described control device, and is configured to be able to control these component devices by the control device. In this embodiment, a common robot controller 124 is used, but each head unit 83 may have a robot controller 124.

  Each sensor amplifier 121 acquires the detection result of the corresponding distance detection sensor 96, amplifies it, and transmits it to the robot controller 124. Each Z-axis motor driver 122 drives the corresponding Z-axis moving mechanism 84 based on the received pulse signal. Each pulse generator 123 converts the movement command signal received from the robot controller 124 into a pulse signal and transmits the pulse signal to the corresponding Z-axis motor driver 122. The robot controller 124 generates a movement command signal based on the detection result from each sensor amplifier 121, and transmits this movement command signal to the corresponding pulse generator 123. The gap measuring means described in the claims is configured by a distance detection sensor 96, a sensor amplifier 121, and a robot controller 124, and the control means described in the claims is configured by a robot controller 124 and a control device.

  Next, the gap adjustment operation by the inkjet apparatus 1 will be described. This gap adjustment operation is performed for each head unit 83, and is continuously and repeatedly performed along with the feeding operation of the recording medium A during the printing process.

  Specifically, first, the detection result of the distance detection sensor 96 is acquired by the sensor amplifier 121. That is, the distance from the distance detection sensor 96 to the outer peripheral surface 71a of the rotary drum 61 is acquired as a detection result. Next, the sensor amplifier 121 transmits the acquired detection result to the robot controller 124. The robot controller 124 that has received the detection result, the detection result, the thickness of the recording medium A stored in advance, the positional relationship between the distance detection sensor 96 and the nozzle surfaces 91 of the plurality of print heads 76 stored in advance, Based on the above, the gap between the nozzle surface 91 and the recording surface A1 of the recording medium A is calculated. Thereafter, the robot controller 124 determines whether or not the calculated gap is an appropriate value (appropriate range). If the calculated gap is an appropriate value, the current gap adjustment operation is terminated.

  On the other hand, if the calculated gap is not an appropriate value, a movement command signal for moving the head unit 83 so that the gap of the head unit 83 becomes an appropriate value is generated and transmitted to the corresponding pulse generator 123. Upon receiving the movement command signal, the pulse generator 123 converts it into a pulse signal and transmits it to the Z-axis motor driver 122. Upon receiving this pulse signal, the Z-axis motor driver 122 drives the Z-axis moving mechanism 84 and moves the head unit 83 based on this pulse signal. As a result, the gap between the nozzle surface 91 and the recording surface A1 is adjusted at any time during the printing process. As described above, by performing the gap adjustment based on the detection result of the distance detection sensor 96, the printing process can be performed with an appropriate gap.

  Next, with reference to FIG. 12, only a different part from the inkjet apparatus 1 of 1st Embodiment is demonstrated about 2nd Embodiment of the inkjet apparatus 1. FIG. As shown in FIG. 12, the inkjet apparatus 1 according to the second embodiment detects the distance of only the head unit 83 (hereinafter referred to as the first head unit 83) that is located most upstream in the medium feeding direction among the plurality of head units 83. The sensor 96 is mounted. In addition, the inkjet apparatus 1 includes, as a control system around the gap adjustment operation, one sensor amplifier 121 corresponding to the distance detection sensor 96, the plurality of Z axis motor drivers 122, the plurality of pulse generators 123, and the above. And a robot controller 124. That is, the plurality of head units 83 have a configuration in which the distance detection sensor 96 and the sensor amplifier 121 are shared.

  In the gap adjustment operation, first, a detection result is acquired from the distance detection sensor 96 by the sensor amplifier 121 and transmitted to the robot controller 124. Receiving this, the robot controller 124 calculates (measures) the gap based on the detection result, and determines whether or not the calculated gap is an appropriate value. If the calculated gap is an appropriate value, the current gap adjustment operation is terminated.

  On the other hand, when the calculated gap is an appropriate value, the robot controller 124 immediately transmits a movement command based on the detection result to the pulse generator 123 for the first head unit 83 as in the first embodiment. On the other hand, for each head unit 83 other than the first head unit 83, the outer peripheral surface 71a at the position where the distance is detected from the medium feeding speed by the rotary drum 61 and the distance from the first head unit 83 to the head unit 83. Calculates the arrival time to reach the head unit 83, and transmits a movement command signal to each pulse generator 123 at the timing when the gap adjustment is completed at the arrival time. That is, in each head unit 83 other than the first head unit 83, the detection result of the distance detection sensor 96 in the first head unit 83 is diverted by delaying the transmission timing of the movement command signal. By performing this gap adjustment operation repeatedly and overlapping with the feeding operation of the recording medium A, the print processing can be performed with an appropriate gap in all the head units 83.

  According to the configuration of the first embodiment and the second embodiment, rotation is performed by measuring the gap between the print head 76 and the recording surface A1, and adjusting the gap so that the gap becomes an appropriate value. Since gap adjustment can be performed following the shape of the outer peripheral surface 71a of the drum 61, printing processing (drawing processing) can always be performed with an appropriate gap. Therefore, the drawing process can be performed with high accuracy.

  Further, by using an eddy current type magnetic sensor as the distance detection sensor 96, gap measurement can be performed in a non-contact manner, so that the outer peripheral surface of the rotating drum 61 is not damaged. Further, unlike the case where the gap measurement is performed by the optical sensor, the gap measurement can be easily and accurately performed even if the outer peripheral surface shape is not stable.

  In the present embodiment, the distance detection sensor 96 is mounted on each head unit 83 or the first head unit 83, but the distance detection sensor 96 may be disposed further upstream of the head unit 83. .

  In this embodiment, an eddy current type magnetic sensor is used as the distance detection sensor 96. However, for example, an ultrasonic type, a laser type (photosensor type), or a contact type may be used.

  Furthermore, in the present embodiment, the gap adjustment is performed by moving the head unit 83 forward and backward in the normal direction of the print feed path L2, but the gap adjustment is performed individually by moving the print head 76 forward and backward. The structure to perform may be sufficient.

  Next, with reference to FIG. 13, only a different part from 1st Embodiment is demonstrated about 3rd Embodiment of the inkjet apparatus 1. FIG. The inkjet apparatus 1 according to the third embodiment includes one distance detection sensor 96 supported by the subframe 53 instead of the plurality of distance detection sensors 96 mounted on the plurality of head units 83. The distance detection sensor 96 faces the print feed path L2 on the upstream side of all the head units 83, and detects the distance to the outer peripheral surface 71a of the rotary drum 61. In addition, the inkjet apparatus 1 includes a sensor amplifier 121 of the distance detection sensor 96, an encoder 125 of the drum motor 64, the plurality of Z-axis motor drivers 122, and the plurality of pulse generators as a control system around the gap adjustment operation. 123 and the robot controller 124. The robot controller 124 receives the detection result of the distance detection from the sensor amplifier 121 and the encoder signal from the encoder 125, while transmitting a movement command signal to each pulse generator 123.

  The gap adjustment operation is performed by a periodic change measurement process that is performed in advance before the printing process and a gap adjustment process (gap correction process) that is continuously and repeatedly performed during the printing process. That is, since the gap between the nozzle surface 91 and the recording surface A1 depends on the shape of the outer peripheral surface 71a of the rotating drum 61, the gap periodically changes with one rotation as one cycle. On the other hand, in the present embodiment, a periodic change of the gap for one rotation in the rotary drum 61 is acquired in advance, and a gap adjustment (gap correction) is performed as needed based on the change during printing processing.

  In the period change measuring step, the gap period change in one rotation (one period) of the rotary drum 61 is measured, and a control table for each Z-axis moving mechanism 84 based on this is generated and stored. Specifically, the encoder 125 transmits an encoder signal (detection result) indicating the rotation angle of the rotary drum 61 to the robot controller 124. On the other hand, the sensor amplifier 121 acquires the detection result of the distance detection from the distance detection sensor 96 and transmits it to the robot controller 124. Receiving these, the robot controller 124 calculates the rotation amount of the rotary drum 61 from the reference position (that is, the feed amount of the recording medium A) from the encoder signal, while the nozzle surface 91 and the recording surface A1 from the detection result of the distance detection. The gap between is calculated. Thereby, gap data corresponding to the feed amount of the recording medium A is acquired. By continuously repeating this series of operations for one rotation, the robot controller 124 shows the correlation (periodic change) between the feed amount of the recording medium A and the amount of change of the gap in each rotation of the rotary drum 61. taking measurement. After that, the robot controller 124 creates a control table for moving so that the gap at each feed amount becomes an appropriate value for each Z-axis moving mechanism 84 (for each head unit 83) based on the measurement result of the periodic change. Generate and store. That is, the control table is generated in consideration of the position of each head unit 83 on the print feed path L2. Here, data for one rotation is acquired for a series of operations here, but data for one and a half rotations or two rotations may be acquired exceeding one rotation. The control table is stored in a storage unit included in the inkjet apparatus 1.

  In the gap adjustment step, the robot controller 124 generates a movement command signal based on each control table so that the gap of each head unit 83 becomes an appropriate value at each feed amount, and transmits the movement command signal to each pulse generator 123. Receiving this, each pulse generator 123 converts this into a pulse signal and transmits it, and each Z-axis motor driver 122 receiving this pulse signal drives the Z-axis moving mechanism 84 based on this pulse signal. . By repeating this series of operations continuously during the printing process, gap adjustment (gap correction) is performed as needed.

  According to the configuration as in the third embodiment, the gap is adjusted so that the gap becomes an appropriate value based on the periodic change of the gap, thereby following the shape of the outer peripheral surface 71a of the rotating drum 61 and the gap. Since the adjustment can be performed, the drawing process can always be performed with an appropriate gap. In addition, since the gap adjustment is performed based on the correlation between the feed amount in one cycle (one rotation) and the amount of change in the gap, the gap adjustment can be easily performed only by performing the gap measurement for one cycle in advance. Can do.

  The periodic change measurement step may be performed only once at the start of driving of the drawing apparatus or at the start of printing. In addition to the measurement at the start of driving or at the start of printing in order to cope with the change over time, A configuration in which re-measurement is periodically performed during driving or printing processing may be employed.

  1: Inkjet device 41: Medium feeding mechanism 61: Rotating drum 71a: Outer peripheral surface 76: Print head 84: Z-axis moving mechanism 91: Nozzle surface 96: Distance detection sensor 121: Sensor amplifier 124 : Robot controller, A: Recording medium, A1: Recording surface, L2: Print feed path

Claims (4)

Medium feeding means for feeding the recording medium along a feeding path following the outer circumferential surface by a rotating body that sends the recording medium in close contact with the outer circumferential surface;
An inkjet head that faces the recording medium being sent and prints on the recording medium;
Gap adjusting means for adjusting the gap between the nozzle surface of the inkjet head and the recording surface of the recording medium by moving the inkjet head back and forth in the normal direction of the outer peripheral surface;
Gap measuring means facing the outer peripheral surface and measuring the gap;
A drawing apparatus comprising: control means for controlling the gap adjusting means so that the gap becomes an appropriate value based on a measurement result of the gap measuring means. The rotating body is made of a dielectric,
The drawing apparatus according to claim 1, wherein the gap measuring unit includes a magnetic sensor that measures an eddy current generated between the rotating body and the rotating body. Medium feeding means for feeding the recording medium along a feeding path following the outer circumferential surface by a rotating body that sends the recording medium in close contact with the outer circumferential surface;
An inkjet head that faces the recording medium being sent and prints on the recording medium;
Gap adjusting means for adjusting the gap between the nozzle surface of the inkjet head and the recording surface of the recording medium by moving the inkjet head back and forth in the normal direction of the outer peripheral surface;
Control means for controlling the medium feeding means, the ink jet head and the gap adjusting means,
The control means is configured to determine the gap based on a control table for the periodic change of the gap, which is defined by a correlation between a feeding amount of the recording medium and an amount of change of the gap in one rotation of the rotary drum. The drawing apparatus, wherein the gap adjusting means is controlled so that the value becomes an appropriate value. A drive control method for a drawing apparatus in which a gap between a nozzle surface of an inkjet head and a recording surface of a recording medium that is printed and fed relative to the inkjet head changes periodically,
A period change obtaining step for obtaining a period change of the gap, which is defined by a correlation between a feed amount of the recording medium and an amount of change of the gap in one period;
And a gap correction step of correcting the gap so as to be an appropriate value based on the acquired periodic change.

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