JP2010125745A - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the occurrence of sudden speed change of an inkjet head and a medium holding part when printing on a surface of a polyhedral medium. <P>SOLUTION: When printing on a surface of a square pillar-like medium M whose adjacent plane parts are connected through a curved surface part, a cubic spline curve passing through eight control points p1 and p2 is calculated, while setting a point corresponding to a center in a periphery direction of each curved surface part of the medium M as a control point p1, and setting a point corresponding to a center of each plane part as a control point p2. By taking the cubic spline curve as a relative moving locus T1 of a nozzle surface of the inkjet head to the surface of the medium M, the inkjet head and the medium holding part are moved relatively. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inkjet printer that performs printing on the surface of a polyhedral medium.

  In recent years, an inkjet printer described in Patent Document 1 has been considered because of a demand for printing even on a three-dimensional medium (for example, see Patent Document 1).

This conventional inkjet printer includes an X-axis drive unit that moves the inkjet head in the horizontal direction, a Z-axis drive unit that moves the media holding unit in the vertical direction, a B-axis drive unit that rotates the media, and an inclination angle of the media And an A-axis drive unit that adjusts the drive, and by driving and controlling each of these drive units, the media holding unit and the inkjet head are relatively moved in the three-dimensional space. Then, printing is performed on the surface of the medium by ejecting ink from the inkjet head while driving and controlling each of these driving units.
JP 2008-108971 A

  However, since conventional ink jet printers consider only spherical media, there is a problem described below when printing on polyhedral media such as a quadrangular prism. That is, when printing on the flat part of the medium, it is only necessary to move the inkjet head horizontally by driving only the X-axis drive part. However, the corner part where the flat part of the medium is connected is printed. In this case, in addition to driving the X-axis drive unit, it is necessary to drive the Z-axis drive unit and the B-axis drive unit to move the media holding unit up and down and rotate the media. For this reason, at the time of switching from the flat portion to the corner portion of the medium, driving of the Z-axis driving unit and the B-axis driving unit that have been stopped until now must be started. There has been a problem that the relative movement between the ink jet head and the media holding unit is delayed due to the change.

  SUMMARY An advantage of some aspects of the invention is that it provides an ink jet printer that can suppress the occurrence of rapid speed changes in an ink jet head and a media holding portion when printing on the surface of a polyhedral medium.

  An ink jet printer according to the present invention is an ink jet printer that performs printing on the surface of a medium by ejecting ink from the ink jet head while relatively moving a medium holding unit that holds polyhedral media and the ink jet head in a three-dimensional space. And having a drive control means for relatively moving the media holding unit and the inkjet head in a three-dimensional space using an approximate curve obtained by approximating the media surface with a curve as a first relative movement locus of the inkjet head with respect to the media. And

  According to the ink jet printer of the present invention, the approximate curve of the polyhedral media surface is the first relative movement locus of the ink jet head with respect to the medium, so that the straight line portion and the curve portion are determined from the relative movement locus of the ink jet head with respect to the medium. There is no connection point. As a result, it is possible to suppress the occurrence of a rapid change in the speed of the media holding unit and the inkjet head, thereby preventing a decrease in printing speed and a printing error due to a delay in relative movement between the media holding unit and the inkjet head. be able to.

  In this case, the approximate curve is preferably a cubic spline curve calculated based on a plurality of control points around the medium. According to this ink jet printer, the cubic spline curve calculated based on a plurality of control points around the medium is used as the first relative movement locus of the ink jet head with respect to the medium, so that the first relative movement locus is smooth. Since it can be a curved line, the relative movement between the media holding unit and the inkjet head can be performed smoothly.

  Further, when the medium is a polygonal column, it is preferable that a point corresponding to the corner of the medium is a control point. According to this ink jet printer, when printing on a polygonal media surface, the direction of the media surface changes abruptly at the corners of the media, but the points corresponding to the corners of the media are used as control points of the cubic spline curve. Thus, since the first relative movement locus corresponding to the corner portion of the medium can be curved, the relative movement between the medium holding portion and the inkjet head can be smoothly performed.

  On the other hand, when the medium is a polyhedron in which adjacent flat portions are connected via a curved surface portion, a point corresponding to the center in the circumferential direction of the curved surface portion of the media is preferably set as a control point. According to this ink jet printer, when printing is performed on a polyhedral media surface in which adjacent flat portions are connected via a curved surface portion, the relative relationship between the media holding portion and the ink jet head at a switching point between the flat surface portion and the curved surface portion of the medium. The direction of movement changes drastically, but by using the point corresponding to the center of the curved surface of the media as the control point of the cubic spline curve, the switching point between the flat and curved surfaces of the media can be eliminated. In addition, since the curvature of the first relative movement locus corresponding to the curved surface portion of the media can be increased, the relative movement between the media holding portion and the inkjet head can be performed smoothly.

  A discharge control unit that discharges ink from the inkjet head to the print target position at a timing at which a normal line passing through the print target position on the media surface matches the normal vector of the first relative movement locus where the inkjet head is located; It is preferable to have. According to this ink jet printer, the timing at which ink is ejected to a predetermined print target position is set to the timing at which the vertical line passing through the print target position matches the normal vector of the first relative movement locus where the ink jet head is located. Thus, since the relationship between the position of the inkjet head and the print target position of the medium can be calculated, ink ejection control can be easily performed.

  The ink jet printer discharges ultraviolet curable ink from the ink jet head, and is configured integrally with the ink jet head and disposed behind the ink jet head in the scanning direction. The ultraviolet ray irradiating means for irradiating the mold ink with ultraviolet rays is further provided, and the drive control means scans the medium, and then sets a predetermined range in which the curvature is equal to or greater than a threshold in the first relative movement locus to the medium. As the movement locus, it is preferable to relatively move the media holding unit and the ultraviolet irradiation unit in the three-dimensional space.

  According to this ink jet printer, since the ultraviolet irradiation means is arranged behind the ink jet head in the scanning direction, the ink jet head discharges the ultraviolet curable ink onto the medium surface and the discharged ultraviolet curable ink by a series of scans. The ink can be irradiated with ultraviolet rays. At this time, the predetermined range in which the curvature of the first relative movement locus is equal to or greater than the threshold is close to the media surface and the inkjet head, but the distance between the media surface and the ultraviolet irradiation means is increased. There is a possibility that ultraviolet rays are not sufficiently irradiated. Therefore, the predetermined range is set as the second relative movement locus of the ultraviolet irradiation means with respect to the medium, and the ultraviolet rays are sufficiently applied to the ultraviolet curable ink ejected on the surface of the medium by relatively moving the media holding unit and the ultraviolet irradiation means. Since it can be irradiated, the ultraviolet curable ink can be completely cured.

  The printing method according to the present invention performs printing on the surface of the medium by ejecting ink from the ink-jet head onto the surface of the medium while relatively moving the medium holding unit that holds the polyhedral medium and the ink-jet head in a three-dimensional space. In the printing method, the medium holding unit and the inkjet head are relatively moved in a three-dimensional space using an approximate curve obtained by approximating the medium surface with a curve as a relative movement locus of the inkjet head with respect to the medium.

  According to the printing method of the present invention, the approximate curve of the polyhedral media surface is set as the first relative movement locus of the inkjet head with respect to the medium, so that the straight line portion and the curved portion are determined from the relative movement locus of the inkjet head with respect to the medium. There is no connection point. As a result, it is possible to suppress the occurrence of a rapid change in the speed of the media holding unit and the inkjet head, thereby preventing a decrease in printing speed and a printing error due to a delay in relative movement between the media holding unit and the inkjet head. be able to.

  ADVANTAGE OF THE INVENTION According to this invention, when printing on the surface of a polyhedral medium, generation | occurrence | production of the rapid speed change of an inkjet head and a media holding part can be suppressed.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of an inkjet printer according to the invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.
[First Embodiment]

  1 is a front view of the ink jet printer according to the present embodiment, FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1, and FIG. 3 is a partial perspective view of the ink jet printer shown in FIG. is there. In this embodiment, the left-right direction in FIG. 1 (front-rear direction in FIG. 2) is the Y-axis direction, the front-rear direction in FIG. 1 (left-right direction in FIG. 2) is the X-axis direction, and the up-down direction in FIG. (Vertical direction of 2) is defined as the Z-axis direction.

  As shown in FIGS. 1 and 2, the inkjet printer 1 according to the present embodiment relatively moves an inkjet head 20 that ejects ink and a media holding unit 40 that holds a square pillar medium M, thereby performing inkjet. By ejecting ink from the head 20, an image or the like is printed on the surface of the medium M. In the present embodiment, the medium M is described as a quadrangular prism in which adjacent flat portions are connected by curved surface portions (R surface portions).

  In the ink jet printer 1, a pair of left and right support legs 11 and 12 are provided upright on a base 10 serving as a base along the Y-axis direction. A first control device 14 equipped with an operation panel 13 for receiving an instruction operation by an operator is fixed to the support leg 11 arranged on the right side in the Y-axis direction, and the support leg arranged on the left side in the Y-axis direction. A second control device 16 on which a maintenance station 15 for cleaning the inkjet head 20 is mounted is fixed to the leg 12.

  The first control device 14 and the second control device 16 are control devices that perform relative movement control between a medium holding unit 40 and an inkjet head 20 described later, ink ejection control of the inkjet head 20, and the like. For this reason, the 1st control apparatus 14 and the 2nd control apparatus 16 function as a drive control means. The first control device 14 and the second control device 16 are mainly configured by a computer including a CPU, a ROM, and a RAM, for example. Each of the above functions is realized by reading predetermined computer software on the CPU or RAM and operating it under the control of the CPU. In the present embodiment, the first control device 14 and the second control device 16 are described as separate units, but may be physically and functionally divided into a plurality of units. Also good.

  A support girder 17 extending along the Y-axis direction is spanned between the pair of left and right support legs 11 and 12. A pair of Y-axis guide rails 18 a and 18 b extending in the extending direction of the support beam 17 are arranged on the upper surface of the support beam 17 in parallel in the X-axis direction. A head carriage 21 on which the inkjet head 20 is mounted is attached to the pair of Y-axis guide rails 18a and 18b so as to be movable in the Y-axis direction.

  The inkjet head 20 prints a color image on the medium M held by the media holding unit 40 by discharging a plurality of colors of ink. Therefore, the inkjet head 20 is provided corresponding to ink colors such as yellow, magenta, cyan, and black. The ink jet head 20 is disposed at the lower end of the head carriage 21 so that the nozzle surface 20 a from which ink is ejected faces the medium M held by the medium holding unit 40.

  The head carriage 21 is connected to a Y-axis transport mechanism (not shown) attached to the support beam 17. The Y-axis transport mechanism is realized by a known mechanism including, for example, a ball screw connected to a drive motor and a ball bearing serving as a bearing for the ball screw. The head carriage 21 is guided by the pair of Y-axis guide rails 18a and 18b and moved in the Y-axis direction by the drive control of the Y-axis transport mechanism by the first control device 14 or the second control device 16. When the inkjet head 20 is positioned above the maintenance station 15 due to the movement of the head carriage 21, the maintenance station 15 moves up and down to clean the inkjet head 20.

  Further, on the upper surface of the base 10, a pair of X-axis guide rails 19 a and 19 b extending in the X-axis direction are arranged in parallel in the Y-axis direction between the pair of support legs 11 and 12. An X table 31 for mounting the media holding unit 40 is attached to the pair of X axis guide rails 19a and 19b so as to be movable in the X axis direction.

  The X table 31 is a table for moving the media holding unit 40 relative to the inkjet head 20 in the X-axis direction, and is connected to an X-axis transport mechanism (not shown) attached to the base 10. The X-axis transport mechanism is realized by, for example, a well-known mechanism including a ball screw connected to a drive motor and a ball bearing serving as a bearing for the ball screw. The X table 31 is provided with a Z-axis support portion 32 extending in the Z-axis direction.

  The Z-axis support part 32 is a support member that supports the media holding part 40 so as to be movable up and down in the Z-axis direction. For this reason, a pair of side wall portions 33a and 33b erected in the Z-axis direction and a top plate portion 34 that connects the upper surfaces of the pair of side wall portions 33a and 33b are attached to the Z-axis support portion 32. And between the pair of side wall portions 33a, 33b, an elevating mechanism 35 for lifting the media holding portion 40 in the Z-axis direction is attached along the side wall portions 33a, 33b.

  The elevating mechanism 35 is disposed between the pair of side wall portions 33a and 33b and is fixed to the X table 31, and is connected to the output shaft of the Z axis drive motor 37 so as to extend in the Z axis direction. The ball screw 38 is erected, and the ball bearing 39 is a bearing of the ball screw 38 and is connected to the media holding unit 40. The ball screw 38 is rotated by the drive control of the Z-axis drive motor 37 by the first control device 14 or the second control device 16, and the ball bearing 39 is moved up and down in the Z-axis direction by the rotation of the ball screw 38. The media holding unit 40 moves up and down in the Z-axis direction.

  The media holding unit 40 holds the medium M in a rotatable manner. Therefore, the media holding unit 40 includes a Z table 41 attached to the ball bearing 39 of the lifting mechanism 35, a pair of arms 42a and 42b protruding from the Z table 41 in the X-axis direction, and a pair of arms 42a and 42b. An A-axis rotating part 43 that is rotatably attached and a chuck 44 that is rotatably attached to the A-axis rotating part 43 and holds the medium M are configured.

  The pair of arms 42a and 42b are opposed to each other in the Y-axis direction and hold the A-axis rotating portion 43 in a rotatable manner. That is, a rotating shaft extending in the Y-axis direction is attached to the tip of a pair of opposed arms 42a and 42b, and an A-axis rotating portion 43 is attached to this rotating shaft. The rotary shaft is connected to the output shaft of the A-axis drive motor 45 fixed to one arm 42a. The A-axis drive motor 45 is rotationally driven in the rotation direction A around the rotation axis attached to the pair of arms 42a and 42b. For this reason, when the A-axis drive motor 45 is driven to rotate, the A-axis rotating unit 43 can rotate in the rotation direction A (A-axis direction).

  The A-axis rotating unit 43 holds the chuck 44 rotatably. That is, the A-axis rotating unit 43 includes a B-axis drive motor 46 that rotates in the rotation direction B around the rotation axis, with the axis in the direction perpendicular to the rotation axis of the A-axis rotating unit 43 serving as the rotation axis. It is attached. A chuck 44 is attached to the output shaft of the B-axis drive motor 46. For this reason, when the B-axis drive motor 46 is driven to rotate, the chuck 44 can be rotated in the rotation direction B (B-axis direction).

  As described above, the rotation of the Z-axis drive motor 37, the A-axis drive motor 45, and the B-axis drive motor 46 causes the media M held by the chuck 44 of the media holding unit 40 to move up and down in the Z-axis direction. At the same time, it rotates in the rotation direction A and the rotation direction B.

  Next, relative movement control between the media holding unit 40 and the inkjet head 20 in the inkjet printer 1 will be described.

  FIG. 4 is a diagram showing a relative movement trajectory of the inkjet head with respect to the medium. FIG. 4 shows a relative movement trajectory of the inkjet head 20 with respect to the medium M in a cross section cut by a plane perpendicular to the rotation axis of the medium, and the direction in which the inkjet head 20 moves relative to the medium M is scanned. The direction is S. In FIG. 4, O is the rotation center of the medium M. As shown in FIG. 4, the inkjet head 20 moves relative to the medium M based on a relative movement trajectory T <b> 1 that approximates the surface of the medium M with a curve. The relative movement trajectory T is obtained by setting a plurality of control points p around the medium M and calculating a cubic spline curve passing through the control points p. In the present embodiment, since the medium M is a quadrangular prism in which adjacent planar portions are connected by curved surface portions, a point corresponding to the circumferential center of each curved surface portion is set as a control point p1, and the center of each planar portion is set. The corresponding point is set as the control point p2. More specifically, a control point p1 corresponding to each curved surface portion is set at a position where the surface of the medium M and the nozzle surface 20a of the inkjet head 20 are closest, and the surface of the medium M and the nozzle surface 20a of the inkjet head 20 are A control point p2 corresponding to each plane portion is set at the most distant position. Then, a cubic spline curve passing through these eight control points p1 and p2 is calculated by a known arithmetic method. Note that the points corresponding to the flat surface portion, the curved surface portion, and the like are points on the surface or the outside of the flat surface portion or the curved surface portion and within the distance at which ink is ejected by the inkjet head 20.

  The relative movement trajectory T1 calculated in this way becomes a convex curve in which the portion corresponding to the flat portion of the surface of the medium M becomes a convex curve and the curvature of the portion corresponding to the curved surface portion of the surface of the medium M becomes large.

  Then, the inkjet printer 1 moves the head carriage 21 in the Y-axis direction by each drive control of the Y-axis, X-axis, Z-axis, B-axis, and A-axis by the first control device 14 and the second control device 16. The media holding unit 40 is moved in the Z-axis direction, and the media M is rotated in the B-axis direction.

  Next, the print schedule will be described with reference to FIGS. FIG. 5 is a diagram showing the positional relationship between the medium and the inkjet head in time series, and FIG. 6 is a diagram showing the positional relationship between the media and the inkjet head after FIG. 5 in time series. . As shown in FIGS. 5 and 6, the inkjet head 20 is moved relative to the medium M while drawing a gentle curve. That is, when printing the flat surface portion of the medium M, as shown in FIG. 5, the nozzle surface 20a of the inkjet head 20 is moved toward the surface of the medium M from the curved surface portion in the scanning direction to the curved surface portion in the scanning direction. After being separated from the predetermined position (see FIG. 5A) (see FIG. 5B), when the intermediate point of the plane portion is exceeded (see FIG. 5C), the medium M is brought closer to the surface (see FIG. 5). 5 (d)). On the other hand, when printing the curved surface portion of the medium M, as shown in FIG. 6, the nozzle surface 20 a of the inkjet head 20 is moved toward the surface of the medium M from the flat portion at the rear in the scanning direction toward the flat portion at the front in the scanning direction. From a predetermined position (see FIG. 6 (a)), it approaches (see FIG. 6 (b)), and when it exceeds the circumferential center point of the curved surface (see FIG. 6 (c)), it moves away from the media surface (see FIG. 6 (c)). (Refer FIG.6 (d)).

  Next, the ink ejection timing will be described with reference to FIG. FIG. 7 is a diagram for explaining the relationship between the print target position of the medium and the ink ejection timing. As shown in FIG. 7, since the normal vector N at a predetermined point on the relative movement trajectory T1 does not necessarily match the surface direction of the medium M, the discharge timing described below is set in a printer driver such as RIP (not shown). Thereafter, ink ejection control is performed in the inkjet printer 1. That is, when printing is performed at a predetermined print target position t on the medium M, in the RIP, first, a vertical line passing through the print target position t and a normal line of the relative movement locus T1 where the nozzle surface 20a of the inkjet head 20 is located. A match with the vector N is determined. Then, the timing at which the vertical line passing through the printing target position t matches the normal vector N of the relative movement trajectory T1 is set as the timing at which ink is ejected from the inkjet head 20 to the printing target position t. In the ink jet printer 1, ink is ejected from the ink jet head 20 toward the print target position t at the timing when the ink ejection timing is set from the RIP.

  As described above, according to the ink jet printer 1 according to the present embodiment, the curve that approximates the surface of the polyhedral medium M is set as the relative movement locus T1 of the nozzle surface 20a of the ink jet head 20 with respect to the medium M. Since the straight line portion disappears from the relative movement locus T1 of the nozzle surface 20a of the head 20, the connection point between the straight line portion and the curved portion in the relative movement locus T1 disappears. As a result, it is possible to suppress the occurrence of a rapid speed change of the head carriage 21 on which the media holding unit 40 and the inkjet head 20 are mounted. Therefore, printing due to the relative movement between the media holding unit 40 and the inkjet head 20 being delayed. It is possible to prevent a decrease in speed and occurrence of printing mistakes.

  In this case, a cubic spline curve calculated based on a plurality of control points p1 and p2 around the medium M is set as a relative movement locus T1 of the inkjet head 20 with respect to the medium M, so that the relative movement locus T1 is smoothed. Since it can be a curved line, the relative movement between the media holding unit 40 and the inkjet head 20 can be performed smoothly.

  In addition, when printing is performed on the surface of a quadrangular prism medium M in which adjacent plane portions are connected via a curved surface portion, the relative relationship between the media holding unit 40 and the inkjet head 20 at a switching point between the planar portion and the curved surface portion of the medium M. However, the point corresponding to the center in the circumferential direction of the curved surface portion of the medium M is set as the control point p1 of the cubic spline curve, so that the switching point between the flat surface portion and the curved surface portion of the medium M is determined. In addition, since the curvature of the relative movement trajectory T1 corresponding to the curved surface portion of the medium M can be increased, the relative movement between the medium holding unit 40 and the inkjet head 20 can be performed smoothly.

In addition, the ink jet head is configured such that the timing at which ink is ejected to a predetermined print target position is set to a timing at which a vertical line passing through the print target position matches the normal vector N of the relative movement locus T1 where the ink jet head 20 is positioned. Since the relationship between the 20 positions and the print target position of the medium M can be calculated, ink ejection control can be easily performed.
[Second Embodiment]

  Next, a second embodiment will be described. The inkjet printer 100 according to the second embodiment is basically the same as the inkjet printer 1 according to the first embodiment, but ultraviolet (hereinafter referred to as “UV light”) is used as ink ejected from the inkjet head 20. The difference is that an ultraviolet curable ink that cures when irradiated (hereinafter referred to as “UV ink”) is ejected. For this reason, in the following description, only the difference between the inkjet printer 100 according to the second embodiment and the inkjet printer 1 according to the first embodiment will be described, and the other description will be omitted.

  FIG. 8 is a partial configuration diagram of an ink jet printer according to the second embodiment. As shown in FIG. 8, the head carriage 21 of the inkjet printer 100 is mounted with an inkjet head 20 that ejects UV ink and a UV lamp 101 that irradiates UV light from the front to the rear in the scanning direction S. . That is, the UV lamp 101 is configured integrally with the inkjet head 20 and is disposed behind the scanning direction S of the inkjet head 20. For this reason, the UV ink ejected from the nozzle surface 20a of the inkjet head 20 to the surface of the medium M is irradiated from the UV lamp 101 in a series of flows due to the movement of the head carriage 21 relative to the medium M in the scanning direction S. Cured by UV light.

  Here, as described above, the relative movement trajectory T1 corresponding to the curved surface portion has a smaller curvature than the relative movement trajectory T1 corresponding to the flat surface portion. However, since the inkjet head 20 and the UV lamp 101 are mounted on the same head carriage 21, the medium M and the UV are within a predetermined range (see FIG. 10) centering on the scanning direction S behind the curved surface portion of the medium M. The distance from the lamp 101 becomes large, and sufficient UV light is not irradiated from the UV lamp 101 to the UV ink, and the UV ink may not be completely cured (see FIG. 9).

  Therefore, in the ink jet printer 100, the portion of the relative range of the predetermined range α centered on the rear side in the scanning direction S of the curved surface portion of the medium M in the relative movement locus T1 is set as the relative movement locus T1 'of the UV lamp 101 with respect to the medium M. Then, after the medium M is rotated once and scanned, the medium M is rotated again, and the head carriage 21 and the medium M are relatively moved so that the UV lamp 101 passes the relative movement locus T1 ′. UV light is emitted from the lamp 101. In this case, only UV light irradiation from the UV lamp 101 is performed without discharging UV ink from the inkjet head 20.

As described above, according to the ink jet printer 100 according to the second embodiment, the UV lamp 101 is arranged behind the ink jet head 20 in the scanning direction S. Therefore, the surface of the medium M by the ink jet head 20 is scanned by a series of scans. The UV ink can be discharged, and the discharged UV ink can be irradiated with UV light. At this time, the predetermined range α in which the curvature of the relative movement locus T1 is equal to or greater than the threshold is close to the surface of the medium M and the inkjet head 20, but the separation distance between the surface of the medium M and the UV lamp 101 is increased. The ink may not be sufficiently irradiated with UV light. Therefore, the predetermined range α is set as a relative movement trajectory T1 ′ of the UV lamp 101 with respect to the medium M, and the medium holding unit 40 and the head carriage 21 are relatively moved, so that the UV ink discharged onto the surface of the medium M can be reduced. Since the UV light can be sufficiently irradiated, the UV ink can be completely cured.
[Third Embodiment]

  Next, a third embodiment will be described. The inkjet printer 1 according to the third embodiment is the same as the inkjet printer 1 according to the first embodiment, and only the relative movement locus is different. For this reason, in the following description, only the relative movement locus T2 in the third embodiment will be described, and the other description will be omitted.

  FIG. 11 is a diagram illustrating a relative movement locus in the third embodiment. In FIG. 11, O is the rotation center of the medium M. As shown in FIG. 11, in the relative movement locus T2 in the third embodiment, a point corresponding to the center in the circumferential direction of each curved surface portion is set as a control point p1, and a point corresponding to the center of each flat surface portion is set as a control point. It is set by p3 and obtained by calculating a cubic spline curve passing through these eight control points p1 and p3. In the third embodiment, each control point p3 is a point corresponding to the center of each plane portion and is closer to the medium M than the control point p2 in the first embodiment. For this reason, the relative movement trajectory T2 in the third embodiment is a curved line that bends in a concave shape in each plane portion.

In this way, since the maximum separation distance between the medium M and the inkjet head 20 can be reduced by making the relative movement trajectory T2 corresponding to each planar portion concave, the printing system on the medium M is improved. Can do.
[Fourth Embodiment]

  Next, a fourth embodiment will be described. The inkjet printer 1 according to the fourth embodiment is the same as the inkjet printer 1 according to the first embodiment, and only the shape of the medium M is different. For this reason, in the following description, only the relative movement locus T3 in the fourth embodiment will be described, and the other description will be omitted.

  FIG. 12 is a diagram showing a relative movement locus in the fourth embodiment. As shown in FIG. 12, the medium M in the fourth embodiment is formed in a square pole having a square cross section. That is, the medium M is formed of four plane portions having the same shape, and is a corner portion formed between adjacent plane portions at 90 °.

  In the relative movement trajectory T3 in the fourth embodiment, a point corresponding to the vertex of each corner is set as a control point p4, and a point corresponding to the center of each plane is set as a control point p5. It is obtained by calculating a cubic spline curve passing through the eight control points p4 and p5. In the relative movement trajectory T3 calculated in this way, a portion corresponding to the flat portion of the surface of the medium M becomes a convex curve, and a portion corresponding to the corner portion of the surface of the medium M also becomes a convex curve.

  As described above, according to the inkjet printer 1 according to the fourth embodiment, when printing on the surface of the quadrangular prism medium M, the direction of the medium M surface changes abruptly at the corner of the medium M. By setting the point corresponding to the portion as the control point p4 of the cubic spline curve, the relative movement trajectory T3 corresponding to the corner portion of the medium M can be curved, so that the medium holding unit 40, the inkjet head 20, Can be smoothly moved.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. For example, in the above-described embodiment, a cubic spline curve is employed as the approximate curve on the media surface. However, the present invention is not limited to the above curve, and other curves may be employed.

  In the above embodiment, as the control point p of the cubic spline curve, a point corresponding to the circumferential center of the curved surface portion, a point corresponding to the center of the flat surface portion, and a point corresponding to the vertex of the corner portion are adopted. Although described above, the present invention is not limited to the above points, and any point may be adopted as long as the cubic spline curve is located outside the medium M.

  Moreover, although the said embodiment demonstrated using the square pole which has a square pole or a curved surface part as the medium M, what kind of media may be employ | adopted if it is a polyhedral medium.

  In the above embodiment, the relative movement trajectory T is described as a relative movement trajectory of the nozzle surface 20a of the inkjet head 20 with respect to the surface of the medium M. However, if the inkjet head 20 can relatively move on the surface of the medium M in a curved shape. The relative movement trajectory of any position of the inkjet head 20 with respect to the surface of the medium M may be used.

  In the above-described embodiment, the first control device 14 and the second control device 16 have been described as realizing the function of the drive control unit. However, the function of the drive control unit may be an ASIC or FPGA mounted on the inkjet printer 1. You may implement | achieve by. The drive control means may be configured by a CPU that controls the entire inkjet printer 1 and an ASIC, FPGA, or the like. With this configuration, it is possible to perform drive control of the inkjet head 20 and the media holding unit 40 appropriately and at high speed.

It is a front view of the inkjet printer which concerns on this embodiment. It is the II-II sectional view taken on the line of FIG. FIG. 2 is a partial perspective view of the ink jet printer shown in FIG. 1. It is the figure which showed the relative movement locus | trajectory of the inkjet head with respect to a medium. It is the figure which showed the positional relationship of a medium and an inkjet head in time series. It is the figure which showed the positional relationship of the media and inkjet head after FIG. 5 in time series. FIG. 5 is a diagram for explaining a relationship between a print target position of a medium and ink ejection timing. The partial block diagram of the inkjet printer which concerns on 2nd Embodiment is shown. FIG. 6 is a diagram illustrating a positional relationship between a carriage and a medium. It is the figure which showed the range where UV light in a medium is not fully irradiated. It is the figure which showed the relative movement locus | trajectory in 3rd Embodiment. It is the figure which showed the relative movement locus | trajectory in 4th Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Three-dimensional inkjet printer, 10 ... Base, 11 ... Support leg, 12 ... Support leg, 13 ... Operation panel, 14 ... 1st control apparatus (drive control means), 15 ... Maintenance station, 16 ... 2nd control apparatus ( Drive control means), 17 ... support spar, 18a, 18b ... Y-axis guide rail, 19a, 19b ... X-axis guide rail, 20 ... ink jet head, 21 ... head carriage, 31 ... X table, 32 ... Z-axis support, 33a, 33b ... side wall part, 34 ... top plate part, 35 ... lifting mechanism, 36a, 36b ... Z-axis guide rail, 37 ... Z-axis drive motor, 38 ... ball screw, 39 ... ball bearing, 40 ... media holding part 41 ... Z table, 42 ... arm, 43 ... A-axis rotating part, 44 ... chuck, 45 ... A-axis drive motor, 46 ... B-axis drive motor, 100 ... ink Ttopurinta, 101 ... UV lamp, M ... medium, N ... normal vector, p ... control point, S ... scanning direction, t ... printed position, T ... relative movement trajectory, alpha ... predetermined range.

Claims (7)

An inkjet printer that performs printing on the surface of the medium by ejecting ink from the inkjet head while relatively moving a medium holding unit and an inkjet head that hold polyhedral media in a three-dimensional space,
Drive control means for moving the media holding unit and the inkjet head relative to each other in a three-dimensional space using an approximate curve obtained by approximating the media surface with a curve as a first relative movement locus of the inkjet head relative to the media. Inkjet printer characterized by.   The inkjet printer according to claim 1, wherein the approximate curve is a cubic spline curve calculated based on a plurality of control points around the medium.   The inkjet printer according to claim 2, wherein when the medium is a polygonal column, a point corresponding to a corner of the medium is set as the control point.   The control point is a point corresponding to the center in the circumferential direction of the curved surface portion of the medium when the media is a polyhedron in which adjacent plane portions are connected via a curved surface portion. The inkjet printer described in 1.   Ejection control for ejecting ink from the inkjet head to the print target position at a timing when a normal line passing through the print target position on the media surface matches the normal vector of the first relative movement locus where the inkjet head is located The inkjet printer according to claim 1, further comprising a section. The inkjet printer is for discharging ultraviolet curable ink from the inkjet head,
An ultraviolet irradiation means configured to be integrated with the inkjet head and disposed behind the inkjet head in the scanning direction to irradiate ultraviolet curable ink discharged from the inkjet head;
The drive control unit scans the medium, and sets the predetermined range in which the curvature is equal to or greater than a threshold in the first relative movement locus as the second relative movement locus of the ultraviolet irradiation unit with respect to the medium, The inkjet printer according to claim 1, wherein the ultraviolet irradiation unit is relatively moved in a three-dimensional space. A printing method for performing printing on a surface of a medium by ejecting ink from the ink-jet head onto the surface of the medium while relatively moving a medium holding unit that holds a polyhedral medium and the ink-jet head in a three-dimensional space. ,
A printing method, wherein the medium holding unit and the inkjet head are relatively moved in a three-dimensional space using an approximate curve obtained by approximating the media surface with a curve as a relative movement locus of the inkjet head with respect to the medium.

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