JP6198634B2 - Curved surface printing system - Google Patents

Description

  The present invention relates to a curved surface printing system, and more particularly to a curved surface printing system capable of printing beautifully and beautifully without unevenness on a printing surface having a curved curved surface portion by an inkjet method.

  Conventionally, in order to print on a large print surface such as a wall surface using the original two-dimensional image data when printing, the print is divided into paper surfaces in advance, and the print is pasted on the print surface. A method has been employed in which printing is performed on a sheet of paper using a large rotating drum and this is adhered to a surface to be printed. However, these methods all need to be printed on a paper surface in advance, and are not directly printed on a large print surface. Therefore, the present inventors have developed an automatic drawing apparatus capable of directly printing on a large print surface such as a wall surface and filed a patent application (Patent Document 1).

  On the other hand, when the print surface has a curved surface, when printing is performed with a conventional two-dimensional printer, the distance between the nozzle that ejects ink and the print surface is not constant on the curved surface portion of the print surface. Therefore, color unevenness occurs in printed characters and designs. In order to solve this, for example, determining whether the printed surface of the component to be printed is a curved surface, and if the printed surface is a curved surface, dividing the printed design into at least two print areas; A configuration has been proposed in which each of the print areas is separately printed in order (Patent Document 2).

JP-A-1-133800 JP 2010-284965 A

  When the surface to be printed is a three-dimensional curved surface, there are a portion that is substantially parallel to a predetermined two-dimensional plane and a portion that is largely inclined with respect to the two-dimensional plane. When the values of the two-dimensional image data corresponding to the parallel portion and the inclined portion are the same, the amount of ink ejected to the parallel portion and the inclined portion is the same. Therefore, as shown in FIG. 10A, for example, in the case where an automobile bonnet is used as the print object 100, when ink is ejected from the nozzle 90, a portion parallel to the two-dimensional plane (FIG. 10B The color density of the portion P) in FIG. 10 is lighter than the portion inclined with respect to the two-dimensional plane (the portion Q in FIG. 10B). As a result, when the printed curved surface is viewed from a certain angle, for example, when the Q portion is viewed from the front, there is a problem that unevenness appears in the darkness of both colors.

  In this regard, in Patent Document 2, the print surface is divided into at least two print areas, a buffer area is provided between them, and when printing is performed on the divided print areas, the print parts are rotated and printed separately. Is going to do. However, when the print object has a surface to be printed such that a delicate curved surface continues like an automobile bonnet, the apparatus becomes large in order to appropriately rotate the print object when printing the curved surface portion. In addition, there is a problem that a high-precision positioning mechanism is required to position the print object so as to correspond to a delicate curved surface, and the cost of the apparatus increases.

  Therefore, in view of the above-described problem, the present invention, for example, in the case of printing on a curved print surface, density unevenness is not caused by a difference in color density between a portion parallel to a two-dimensional plane and a portion inclined. It is an object of the present invention to provide a curved surface printing system that enables printing without causing the occurrence of ink.

To achieve the above object, the present invention according to claim 1 is a curved surface printing system for printing on a printed surface having a curved surface portion, wherein the horizontal direction is the X axis, the vertical direction is the Y axis, and the depth direction is Z. A print head having a large number of nozzles for ejecting ink in the Z-axis direction in a three-dimensional coordinate space constituted by three axes orthogonal to each other as the axis, and moving the print head in at least the X-axis direction and the Y-axis direction Moving means for holding, holding means for holding the printed surface so as to oppose the ink ejection direction of the print head, and the print head for the printed surface based on two-dimensional image data to be printed Control means for controlling the movement of the ink and the ink discharge amount, wherein the control means converts the two-dimensional image data into the print target. Divide the two-dimensional plane consisting of the X-axis direction and Y-axis direction into the area to be printed into a large number of matrices by dividing the two-dimensional plane by lines parallel to the X-axis and Y-axis, and create a number of minute unit two-dimensional planes. units of area as S _a, if the area of the three-dimensional surface number of minute unit by projecting parallel the unit two-dimensional plane on the printing surface was S _B, corresponding to the three-dimensional surface arbitrary units The control of the ink discharge amount is performed so that an amount of S _B / S _A times the amount of ink discharge specified on the two-dimensional plane based on the two-dimensional image data is discharged to the corresponding arbitrary unit three-dimensional surface. It is characterized by performing.

  In order to achieve the above object, according to a second aspect of the present invention, in the curved surface printing system according to the first aspect, the ink tank holding the ink is pressurized to a predetermined pressure and pressurized from the nozzle. Ink is ejected.

  According to the curved surface printing system according to the present invention, even when printing is performed on a curved print surface, it is possible to perform beautiful printing without density unevenness without any difference in color density in any part. There is. Further, since the ink is pressurized and ejected, the ink can be ejected accurately and far away, and the print finish becomes more beautiful.

1 is a diagram illustrating an overall configuration of an embodiment of a curved surface printing system according to the present invention. It is a perspective view which shows the detailed structure of a drive part. It is a perspective view which shows the raising / lowering mechanism which raises / lowers a movable unit. It is a side view which shows the structure of the stopper of a raising / lowering mechanism. It is a block diagram which shows a print head and a database part. FIG. 2 is a configuration diagram illustrating details of a print head. FIG. 3 is a diagram illustrating an ink tank that supplies ink to a print head and a peripheral configuration thereof. It is explanatory drawing which shows the relationship between a unit two-dimensional plane and the unit three-dimensional plane corresponding to it. It is a flowchart explaining operation | movement of the curved surface printing system which concerns on this invention. (A) is explanatory drawing which shows the state which divided the to-be-printed surface into many matrices, (b) is a side view of (a).

[Configuration of curved surface printing system]
Hereinafter, a curved surface printing system according to the present invention will be described in detail based on a preferred embodiment with reference to the drawings. FIG. 1 is a diagram showing an overall configuration of an embodiment of a curved surface printing system according to the present invention. A curved surface printing system 1 shown in FIG. 1 generally includes a movable frame unit 2 that is installed facing a print object 100 (curved on a hood of an automobile in FIG. 1) having a curved surface on a printed surface, and a frame unit 2. A movable unit 13 attached to the left and right frame members 10 and 11 so as to be able to move up and down in the vertical direction (Y-axis direction) and a motor (not shown) are incorporated in the horizontal direction ( Drive unit 3 disposed so as to be capable of reciprocating in the (X-axis direction), print head 4 attached to the drive unit 3 and ejecting ink toward the print object 100, and ink ejection from nozzles of the print head 4 A controller 5 that controls the reciprocating movement of the drive unit 3 and the elevation of the movable unit 13, and a PC (personal computer) that instructs the controller 5. And Le computer) 6 is configured to include a database unit (DB unit) 7 for recording and storing information about the print object 100, such as shape and size.

  The frame unit 2 is vertically and horizontally attached to both the upper and lower frame members 8, 9, 10, and 11 formed by metal columnar bodies and the lower frame member 9 in order to make the frame unit 2 independent. The left and right leg members 12a and 12b are provided. The movable unit 13 spanned between the left and right frame members 10 and 11 is configured to be movable up and down while supporting the drive unit 3. The print object 100 is arranged perpendicular to the ink ejection direction (Z-axis direction), that is, so as to face the plane formed by the upper, lower, left and right frame members 8, 9, 10, 11 of the frame unit 2. However, in order to place the print target at a predetermined position to be printed, for example, the back side of the print target surface of the print target 100 is sucked and held by a chuck attached to the tip of the arm of an articulated arm robot. Can be done. By using an articulated arm robot, the print object 100 can be accurately placed at the print position, and the posture of the print object 100 can be changed as appropriate. Depending on the shape of the print object 100, the left and right sides may be drawn separately. However, since an articulated arm robot can perform accurate positioning, problems such as misalignment do not occur.

  Here, as shown in FIG. 1, the bonnet that is the print object 100 is set vertically so that the printed surface is positioned at right angles to the Z-axis direction, which is the ink discharge direction. The reason for this is that when the print target surface of the print object 100 is arranged so as to be horizontal, a holding base for holding the print object 100 horizontally is required. This is because the frame unit 2 including the drive unit 3 and the print head 4 must be horizontally disposed above the print object 100, and the curved surface printing system 1 is increased in size.

  FIG. 2 is a perspective view showing a detailed configuration of the drive unit 3. As described above, the drive unit 3 is disposed so as to be reciprocally movable in the horizontal direction (X-axis direction) on the movable unit 13. The movable unit 13 includes a rail 30 disposed horizontally so as to be bridged between the left and right frame members 10 and 11 of the frame unit 2, and a rack gear 31 disposed so as to be parallel to the rail 30. A linear guide 32 that is fitted on a part of the rail 30 and moves while sliding, a pinion gear unit 33 that is connected to the linear guide 32 and meshes with the rack gear 31, and a speed reducer that rotationally drives the pinion gear unit 33. A motor 34 with 36 and a rotary encoder 35 for detecting the drawing point position are provided. By driving the motor 34 (forward rotation or reverse rotation), the print head 4 is moved rightward or leftward along the movable unit 13. The drive unit 3 functions as a drive mechanism for the print head 4 in the X-axis direction. Reference numerals 37a and 37b attached to both sides of the casing of the speed reducer 36 are limit switches for defining the range of the travel stroke.

  FIG. 3 is a perspective view showing an elevating mechanism 20 for elevating the movable unit 13. The lift mechanism 20 shown in the figure is schematically composed of a rack gear 21 arranged in the vertical direction (Y-axis direction) parallel to the left and right frame members 10 and 11 of the frame unit 2, and a pinion gear (not shown) that meshes with the rack gear 21. And a stepping motor 23 with a gear head serving as a drive source for the moving body 22. The elevating mechanism 20 is built in the left and right frame members 10 and 11, and moves the movable unit 13 upward or downward by forward or reverse rotation of the stepping motor 23. In addition, limit switches 37 c and 37 d for defining the lifting range of the movable unit 13 are provided above and below the casing of the moving body 22.

  FIG. 4 is a side view showing the structure of the stopper of the lifting mechanism 20. The movable unit 13 includes a solenoid 24 attached to the moving body 22 and a stopper body 25 connected to the movable shaft of the solenoid 24 in order to keep the stepping motor 23 stationary when not excited. The stopper body 25 is configured to engage with the rack gear 21 when the stepping motor 23 is stationary. This prevents the movable unit 13 from falling naturally. The print head 4 only needs to be movable in at least the horizontal direction (X-axis direction) and the vertical direction (Y-axis direction), but can also be moved in the direction orthogonal to the print surface (Z-axis direction). It may be formed.

  FIG. 5 is a block diagram showing details of the print head 4 and the database unit 7. The controller 5 controls ink ejection from the nozzles of the print head 4, reciprocation of the drive unit 3, and elevation of the movable unit 13. The controller 5 includes a nozzle drive unit 51 that controls on / off of ejection of each nozzle provided in the print head 4, a Y-axis drive unit 52 that drives the movable unit 13 in the Y-axis direction, and a drive unit 3 that is driven by X. An X-axis drive unit 53 that drives in the axial direction and an image processing unit 54 that processes an image to be printed on the printing surface of the print object 100 are configured. On the other hand, the database unit 7 is a printed surface database unit (printed surface DB) that records and stores information related to the printed surface such as the shape and size of the print object 100 and curved surface data (3D shape data) of the printed surface. 7a and an image database (image DB) 7b for recording and storing original two-dimensional image data for printing on the print object 100.

  FIG. 6 is a block diagram showing details of the print head. The print head 4 generally includes ink jet nozzles that eject ink of a predetermined color from the nozzles to perform printing on the print object 100. Specifically, black (K), cyan (C), magenta A nozzle group 40 including a plurality of nozzles from which inks of each color (M), yellow (Y), and white (W) are ejected is provided. The nozzle group 40 includes a black nozzle group 40a in which a plurality of nozzles that eject black ink are arranged in a row, a cyan nozzle group 40b in which a plurality of nozzles that eject cyan ink are arranged in a row, and ejects magenta ink. A magenta nozzle group 40c in which a plurality of nozzles are arranged in a row, a yellow nozzle group 40d in which a plurality of nozzles that eject yellow ink are arranged in a row, and a plurality of nozzles that eject white ink are arranged in a row The white nozzle group 40e is formed. The nozzle groups 40 a to 40 e are driven by a drive signal sent through the nozzle drive signal line 41. Reference numerals 15a to 15e denote tubes for supplying ink to the nozzles, and 15 denotes a tube group.

  FIG. 7 is a diagram showing an ink tank for supplying ink to the print head 4 and its peripheral configuration. As shown in FIG. 7, each nozzle group 40 provided in the print head 4 communicates with ink tanks 14a to 14e filled with black, cyan, magenta, yellow, and white inks, respectively. That is, one end of each of the tubes 15 a to 15 e communicates with each of the ink tanks 14 a to 14 e forming the ink ink tank group 14, and the other end communicates with the print head 4. Specifically, the ink tank black 14a filled with black ink and the black nozzle group 40a communicate with each other via a tube 15a, and the ink tank cyan 14b and cyan nozzle group 40b filled with cyan ink pass through the tube 15b. The ink tank magenta 14c filled with magenta ink and the magenta nozzle group 40c communicate via the tube 15c, and the ink tank yellow 14d filled with yellow ink and the yellow nozzle group 40d pass through the tube 15d. The ink tank white 14e filled with white ink and the white nozzle group 40e communicate with each other via a tube 15e. The pressurized air from the air compressor 16 is adjusted to a predetermined pressure by the air regulator 17 and sent to each ink tank 14 via the pipe 18 to pressurize the inside of the tank.

Next, control performed by the controller 5 when ink is ejected onto the curved surface will be described. FIG. 8 is an explanatory diagram showing the relationship between the unit two-dimensional plane and the corresponding unit three-dimensional plane. First, based on the two-dimensional image data of the original image when printing on the print surface of the print object 100, this is expanded from the X-axis direction and the Y-axis direction to the range to be printed on the print surface. Set a two-dimensional plane. Then, the set two-dimensional plane is divided into a large number of fine matrices by lines parallel to the X axis and the Y axis (see FIG. 10A). Then, the area of the large number of small units two-dimensional plane A that can be split and S _A. In FIG. 10A, for convenience of explanation, the dimension plane is drawn large in units, but the actual unit two-dimensional plane A is extremely small, for example, about 0.08 × 0.08 mm.

Then, the area of the number of minute unit three-dimensional surface B capable unit two-dimensional plane A by projecting parallel onto a printing surface of a printing object 100 and S _B, the printing on the three-dimensional surface B arbitrary units In the case of performing this, S _B / S _A times the required ink ejection amount designated based on the two-dimensional image data for printing on the unit two-dimensional plane A corresponding to the arbitrary unit three-dimensional plane B The amount of ink is ejected onto the corresponding arbitrary unit three-dimensional surface B. That is, as shown in FIG. 8, to be printed surface of the printed object 100 to one optional small units two-dimensional plane A as viewed from the Z direction is A face and the area as S _A. The A surface is set orthogonal to the ink ejection direction. Next, a unit three-dimensional surface B formed on the extended lines of the four corners of the unit two-dimensional plane A, that is, the A surface by parallel projection, is formed as a B surface. Then, the inclination of the Y-axis of the B plane to the surface A beta, when the inclination of the X-axis and alpha, the area S _B of the B-side is as follows.

[Equation 1]
Area S _B = Area S _A / (cos α × cos β) (1)

From Equation 1, with respect to the amount of ink discharged d ₁ from the nozzle which is specified based on the two-dimensional image data to an area S _A is not considered a curved surface, discharged ink amount d ₂ with respect to the area S _B in consideration of the curved surface The amount is represented by the following formula.

[Equation 2]
d ₂ = d ₁ × (S _B / S _A ) (2)

  When this is performed for each unit three-dimensional surface B, the amount of ink ejected between the parallel portion and the inclined portion is adjusted even when the print surface of the print object 100 is curved, and the plane portion. The color density does not differ between the inclined portion and the inclined portion. Therefore, a beautiful print without density unevenness can be obtained.

[Operation of curved surface printing system]
Next, the operation of the curved surface printing system 1 described above will be described. FIG. 9 is a flowchart for explaining the operation of the curved surface printing system 1. First, the print object 100 is set so as to face the frame unit 2 including the drive unit 3, the print head 4, and the lifting mechanism 20 (see FIG. 1). The print object 100 is accurately positioned and held by an articulated arm robot (not shown).

  Next, necessary data such as data relating to the shape of the print object 100, size, print data, material, number of prints and the like are stored in the print surface DB 7a, and image data for specifying the print contents is stored in the image DB 7b and printed. Data necessary for the acquisition is acquired (step S1). Then, a print start command is waited (step S2), and when a print start command is issued (step S2; Yes), data relating to the shape of the print object 100 is read (step S3).

When the data necessary for printing is acquired, the controller 5 performs the following control. That is, as described above, based on the two-dimensional image data of the original image when printing on the print surface of the print object 100, the X-axis direction developed to the range to be printed on the print surface; A two-dimensional plane consisting of the Y-axis direction is set. The set two-dimensional plane is divided into a large number of fine matrices by lines parallel to the X-axis and the Y-axis, and a large number of minute unit two-dimensional planes A formed by the division are printed on the object 100 to be printed. A unit three-dimensional plane B is formed by parallel projection on the plane. Then, the number 1 described above, performs the calculation shown in Equation 2 (step S4), and the amount d ₂ of ink ejected to the unit three-dimensional surface B is set, the amount d set for each of the unit three-dimensional surface B _{The second} ink is ejected and printing is performed (step S5). The amount of ink ejected can be controlled by the ejection time or the number of ejections.

  When printing is completed (step S7), the PC 6 operates the drive unit 3 to return the print head 4 to the home position (HP) (step S7). In this way, the printing operation on the print surface of the print object 100 is completed.

[Effect of the embodiment]
Thus, according to the curved surface printing system in the present embodiment described above, the ink discharge amount d ₂ with respect to the unit three-dimensional surface B (area S _B ) of the print surface of the print object 100 is set to the area S of the unit two-dimensional plane A. _{Since A} is S _B / S _A times, even when printing is performed on the curved surface of the print object 100, it is possible to perform beautiful printing without color density unevenness between the parallel portion and the inclined portion. There is an effect that it becomes possible.

  As described above, the preferred embodiments of the present invention have been described in detail. However, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Needless to say, it is possible to modify or change the above. For example, the ink color is not limited to the above-described color, and it is also possible to use a specific color ink for all.

  If a clear liquid for clear coating is used instead of ink, it can be used as a clear coating system.

DESCRIPTION OF SYMBOLS 1 Curved surface printing system 2 Frame unit 3 Drive part 4 Print head 5 Controller 6 PC
7 Database part (DB part)
8-11 Frame member 12a, 12b Leg member 13 Movable unit 14 Ink tank group 14a-14e Ink tank 15a-15e Tube 16 Air compressor 17 Air regulator 18 Ink tank pressurized air pipe 20 Lifting mechanism 21 Rack gear 22 Moving body 23 Stepping motor 30 Rail 31 Rack gear 32 Linear guide 33 Pinion gear unit 34 Motor with reduction gear 35 Drawing point position detection rotary encoder 36 Reducer 37a to 37d Limit switch 40 Nozzle group 40a Black nozzle group 40b Cyan nozzle group 40c Magenta nozzle group 40d Yellow nozzle group 40e White nozzle group 41 Cable 41 Nozzle drive signal line 42, 43 Signal line 51 Nozzle drive unit 52 Image processing unit 53 Y-axis drive unit 5 X-axis driving unit 100 print object

Claims (2)

In a curved surface printing system for printing on a printed surface having a curved surface portion,
A print head having a large number of nozzles for ejecting ink in the Z-axis direction in a three-dimensional coordinate space composed of three axes orthogonal to each other with the horizontal direction as the X-axis, the vertical direction as the Y-axis, and the depth direction as the Z-axis When,
Moving means for moving the print head at least in the X-axis direction and the Y-axis direction;
Holding means for holding the printed surface so as to face the ink ejection direction of the print head;
Control means for controlling the movement of the print head relative to the print surface and the ink discharge amount based on the two-dimensional image data that is the basis of printing;
The control means forms a two-dimensional plane composed of the X-axis direction and the Y-axis direction, in which the two-dimensional image data is expanded to the range to be printed on the print surface, into a plurality of matrices by lines parallel to the X-axis and the Y-axis dividing the area of a large number of small units two-dimensional plane that can be divided as S _a, the area of the three-dimensional surface number of minute unit by projecting parallel the unit two-dimensional plane on the printing surface S _In the case of _B , an arbitrary unit corresponding to an amount of ink that is S _B / S _A times the ink discharge amount specified based on the two-dimensional image data for a unit two-dimensional plane corresponding to an arbitrary unit three-dimensional surface A curved surface printing system that controls the amount of ink discharged so as to be discharged onto a three-dimensional surface. The curved surface printing system according to claim 1,
A curved surface printing system, wherein an ink tank holding the ink is pressurized to a predetermined pressure, and the pressurized ink is ejected from the nozzle.

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