JP2019034524A - Image forming apparatus and image forming system - Google Patents

Abstract

To provide an image forming apparatus which facilitates position adjustment and maintenance of a head, and can reduce a workload of a user on a head provided on a conveyance line.SOLUTION: An image forming apparatus includes a head 5, a movement section and a control section. The head discharges ink onto a printing surface of an article from a nozzle based on image data, and prints an image. The movement section moves the head in at least two axial directions. The control section controls the movement section. One of the two axial directions is a Z-axis direction which is a depth direction when the printing surface is set to be a front surface.SELECTED DRAWING: Figure 7

Description

  The present invention relates to an image forming apparatus that prints on an article by discharging ink from nozzles. The present invention also relates to an image forming system that conveys an article and performs printing.

  An apparatus for printing on an article to be conveyed may be provided in a factory. For example, a printing device may be provided on a line for packing products. For example, a box filled with merchandise is an article. The box in which the goods are packed is often a cardboard box. An example of an apparatus for printing on an object that flows along such a line is described in Patent Document 1.

Specifically, in Patent Document 1, a packaging box in which a product is stored is transported, and both sides of the packaging box are sandwiched by guide plates on both sides of the transport device in a direction perpendicular to the transporting direction of the packaging box. There is described a printing apparatus that includes a printer that positions a predetermined position and prints predetermined characters, figures, or symbols on the side of a packing box that is disposed and conveyed slightly backward from the guide plate. With this configuration, the information can be directly printed on the packaging box (Patent Document 1: Claim 1, paragraph [0006]).

Japanese Patent Laid-Open No. 10-077013

  A printing head may be provided in the middle of a line (conveyance line) for conveying products and packages. The object to be conveyed is the object to be printed. The print head prints on the print object. The print head prints by discharging ink. For example, product information and date of manufacture are printed. When passing in front of the printing head, ink is sprayed onto the object to be printed. Thereby, an image is printed on the printing object. The printing head is fixed with a fixture so as not to shake during ink ejection. This prevents the image quality of the printed image from being degraded. When you want to move the position of the print head, remove the fixture manually.

  Conventionally, the printing head cannot be moved at all while it is stopped by a fixture. When adjusting the position of the printing head, the operator loosens the fixture (fastener). Adjust the print head position by hand. Thereafter, the operator retightens the fixture so that the position of the printing head does not shift. The print head may be removed during cleaning. Also, the printing head may be replaced due to a failure. In these cases, it is necessary to manually remove the fixture. As described above, conventionally, there is a problem that the position adjustment and maintenance of the printing head are troublesome. In addition, the position adjustment, maintenance, and conveyance line are stopped. The operation rate of the transfer line is reduced.

  Moreover, clogging may occur at the nozzles of the printing head during use. When clogging occurs, it is necessary to clean the printing head. Since the printing head is fixed, it may take time for the cleaning work.

  The printing apparatus described in Patent Document 1 conveys a packing box. In this printing apparatus, the printer that prints on the packaging box is fixed. The above problem cannot be solved.

  In view of the above-described problems, the present invention facilitates head position adjustment and maintenance, and reduces the work burden on the user related to the head provided in the transport line.

  An image forming apparatus according to the present invention includes a head, a moving unit, and a control unit. The head includes nozzles arranged in a line. The head prints an image by ejecting ink from the nozzles onto a printing surface of an article based on image data. The moving unit moves the head in at least two axial directions. The control unit controls the moving unit. Each said axial direction is orthogonal. One of the two axial directions is a Z-axis direction that is a depth direction when the printing surface is the front surface.

  According to the present invention, it is possible to provide an image forming apparatus capable of easily adjusting the head position and performing maintenance. It is possible to reduce the work burden on the user regarding the head provided in the line.

1 is a diagram illustrating an example of an image forming system according to an embodiment. 1 is a diagram illustrating an example of an image forming apparatus according to an embodiment. It is a figure which shows an example of the head which concerns on embodiment. It is a figure which shows an example of the head which concerns on embodiment. An example of the moving part which concerns on embodiment is shown. An example of the figure which looked at the image forming apparatus from the upper surface is shown. 1 is a diagram illustrating an example of a perspective view of an image forming apparatus. FIG. 5 is a diagram illustrating an example of a head retraction flow in the image forming apparatus according to the embodiment. FIG. 6 is a diagram illustrating an example of a flow of cleaning the head of the image forming apparatus according to the embodiment. 2 illustrates an example of a flow of inputting printing data to an image forming apparatus according to an embodiment. It is a figure which shows an example of the printing in the stop goods printing mode which concerns on embodiment. It is a figure which shows an example of the flow of printing of the stop goods printing mode which concerns on embodiment. It is a figure which shows an example of the printing in the head fixed mode which concerns on embodiment. It is a figure which shows an example of the flow of printing of the head fixed mode which concerns on embodiment. It is a figure which shows an example of the printing in the head movement mode which concerns on embodiment. It is a figure which shows an example of the flow of printing of the head movement which concerns on embodiment. It is a figure which shows an example of the conveying apparatus which concerns on embodiment. An example of the definition data which concerns on embodiment is shown. An example of the image type selection screen which concerns on embodiment is shown. An example of the smoothness level selection screen which concerns on embodiment is shown. It is a figure which shows an example of the flow of a movement of the Z axis direction of the head which concerns on embodiment. It is a figure which shows an example of the ink discharge amount data which concern on embodiment. FIG. 5 is a diagram illustrating an example of a process for changing nozzles used in the image forming apparatus according to the embodiment. FIG. 5 is a diagram illustrating an example of a process for changing nozzles used in the image forming apparatus according to the embodiment. It is a figure which shows an example of the flow of adjustment of the discharge time interval accompanying the change of the Y-axis fixed position which concerns on embodiment. FIG. 4 is a diagram illustrating an example of a portion related to photographing of a printing surface in the image forming apparatus according to the embodiment. It is a figure which shows an example of the flow of the image automatic addition mode which concerns on embodiment. It is a figure which shows an example of the flow of the copy mode which concerns on embodiment. It is a figure which shows an example of the image forming apparatus which concerns on a modification. It is a figure which shows an example of the image forming apparatus which concerns on a modification. It is a figure which shows an example of the flow of a movement of the Z-axis direction of the head which concerns on a modification.

  The image forming system 100 according to the embodiment will be described below with reference to FIGS. The image forming system 100 includes an image forming apparatus 1 and a transport device 3 that transports an article 2. Each element such as configuration and arrangement described in the description of the present embodiment is merely an illustrative example without limiting the scope of the invention.

(Image forming system 100)
An example of the image forming system 100 according to the embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating an example of an image forming system 100 according to the embodiment.

  The conveyance device 3 is a device that conveys the article 2. The conveyance device 3 includes a plurality of conveyance rollers. Article 2 is placed on the roller. The transport roller rotates. The conveyance device 3 conveys the article 2 at a constant speed. The conveying device 3 conveys the article 2 in the X-axis direction, which is the width direction when the printing surface 21 of the article 2 is the front.

  In FIG. 1, a packaging box (assembled cardboard box) in which products are stored is illustrated as an example of the article 2. For example, a printing container is stored in the packing box. The printing container is a container that contains a color material such as toner or ink. For example, the toner container may be referred to as a toner container. In addition, it is not specifically limited to the goods stored in a packaging box. The article 2 is not limited to a packing box.

  The image forming apparatus 1 performs printing on the conveyed article 2. As shown in FIG. 1, the image forming apparatus 1 is provided on a base 1a. In other words, the image forming apparatus 1 includes the base 1a. Rollers 1b are provided on the lower surface of the base 1a and at the four corners of the base 1a. The entire image forming apparatus 1 can be pushed and moved. That is, the image forming apparatus 1 can be installed later on the transport line (transport device 3). For example, the image forming apparatus 1 can be added to an existing conveyance line. The existing conveyance device 3 and the image forming apparatus 1 can be combined to form the image forming system 100. Further, the image forming system 100 may be constructed by combining the image forming apparatus 1 and the conveyance device 3 dedicated to the image forming apparatus 1.

  The image forming apparatus 1 can perform printing on the article 2 being conveyed (moving). For example, the transport device 3 transports the article 2 at a constant speed. The head 5 of the image forming apparatus 1 prints on the article 2 being conveyed. Printing can be performed without stopping the line conveyance of the article 2.

  Conventionally, the printing head is fixed. In this case, in order to print an image two-dimensionally, it is necessary to move the print target. On the other hand, the image forming apparatus 1 can move the head 5 three-dimensionally (details will be described later). Therefore, the image forming apparatus 1 can perform printing on the stopped article 2. In FIG. 1, a transport device 3 that switches the transport direction of the article 2 by 90 degrees on the front surface of the image forming apparatus 1 is illustrated. In the example of FIG. 1, the transport device 3 stops the article 2 once in front of the image forming apparatus 1. That is, the transport device 3 stops the article 2 before the head 5 starts printing (before ink ejection). The head 5 of the image forming apparatus 1 prints on the stopped article 2. After the printing by the head 5 is completed, the conveyance device 3 resumes conveyance of the article 2. The conveyance device 3 conveys the next article 2 (unprinted article 2) to the front surface of the image forming apparatus 1 and stops it.

(Image forming apparatus 1)
Next, an example of the image forming apparatus 1 according to the embodiment will be described with reference to FIGS. 1 and 2. FIG. 2 is a diagram illustrating an example of the image forming apparatus 1 according to the embodiment.

  The image forming apparatus 1 includes a control unit 4. The control unit 4 controls the operation of the image forming apparatus 1. The control unit 4 is a substrate. A control unit 4 is provided inside the control device 10 shown in FIG. The control unit 4 includes a CPU 41 and an image processing unit 42. The image processing unit 42 performs image processing on the image data D2 used for printing. The CPU 41 performs processing based on the control program and control data stored in the storage unit 43. The storage unit 43 includes a nonvolatile storage device such as a ROM, an HDD, or a flash ROM. The storage unit 43 includes a volatile storage device such as a RAM.

  The image forming apparatus 1 includes a head 5. The head 5 includes nozzles 51 arranged in a row. In the following description, an example in which the head 5 ejects black ink will be described. As shown in FIGS. 1 and 2, the image forming apparatus 1 is provided with a plurality of ink tanks 11. Ink is filled in the ink tank 11. Ink is supplied from the ink tank 11 to the head 5. In FIG. 1, three tanks are shown. Among the ink tanks 11 in FIG. 1, the leftmost ink tank 11 is a sub tank. The sub tank supplies ink to the head 5. A sub tank is provided to generate a water head difference between the head 5 and the ink upper surface in the sub tank. The sub-tank is provided at a position where ink leakage and defective ejection do not occur and the water head difference is appropriate. The rightmost ink tank 11 is a main tank. The main tank supplies ink to the sub tank. The central ink tank 11 is a tank for collecting unnecessary ink.

  The head 5 may be compatible with color printing. For example, the head 5 may eject black, cyan, magenta, and yellow ink. In the case of the color-compatible head 5, the nozzles 51 of the respective colors are arranged in a line.

  The control unit 4 causes the head 5 to print an image. The control unit 4 causes ink to be ejected from the nozzles 51 of the head 5 onto the printing surface 21 of the article 2 based on the image data D2. The image forming apparatus 1 includes a moving unit 6. The moving unit 6 moves the head 5 in at least two axial directions. Specifically, the moving unit 6 moves the head 5 in three axis directions. The moving unit 6 includes a first moving mechanism 61, a second moving mechanism 62, and a third moving mechanism 63. The first moving mechanism 61 moves the head 5 in the Z-axis direction. The second moving mechanism 62 moves the head 5 in the Y axis direction. The third moving mechanism 63 moves the head 5 in the X-axis direction. The Z-axis direction is the depth direction when the printing surface 21 is the front surface. The Y-axis direction is the height direction when the printing surface 21 is the front surface. The X-axis direction is the horizontal (width) direction when the printing surface 21 is the front surface. The X-axis direction is also the conveyance direction of the article 2. The head 5 is attached to the moving unit 6 so that the nozzles 51 are arranged along the Y-axis direction. The control unit 4 controls the moving unit 6. That is, the control unit 4 controls the position of the head 5.

  The speed sensor 44 is a sensor for detecting the moving speed of the article 2 in the X-axis direction. For example, the speed sensor 44 irradiates the article 2 with laser light, microwaves, ultrasonic waves, or the like. The speed sensor 44 measures the speed from the frequency change of the reflected wave of the article 2. The speed sensor 44 inputs a signal indicating the measured speed to the control unit 4. The control unit 4 recognizes the conveyance speed of the article 2 based on the output of the speed sensor 44. When printing only on the stopped article 2, the speed sensor 44 is not necessary.

  The image forming apparatus 1 includes a cap unit 7. The cap part 7 is put on the head 5. When preventing the ink from drying, the control unit 4 moves the head 5 to the moving unit 6 to the position of the cap unit 7. The cap part 7 is a member obtained by coating a sheet metal with rubber. For example, the cap part 7 has a concave shape. The end portion on the exposed surface side of the head 5 is fitted into the recessed portion. The exposed surface is a surface of the head 5 where the nozzle 51 is exposed. The cap part 7 seals the exposed surface of the nozzle 51. The cap unit 7 prevents ink from evaporating from the nozzles 51.

  The image forming apparatus 1 includes a cleaning unit 8. The cleaning unit 8 includes a cleaning member 81 and a cleaning unit 82. The cleaning member 81 has a plate shape (blade). The cleaning member 81 is made of rubber, for example. During cleaning, the tip of the blade is applied to the nozzle 51. The control unit 4 moves the head 5 to the moving unit 6 for cleaning the nozzle 51. The head 5 moves the head 5 so that the tip of the nozzle 51 is rubbed with a blade. Thereby, the cleaning member 81 scrapes off dust, dust, and ink with increased viscosity.

  The cleaning unit 82 flows (sprays) the cleaning liquid onto the cleaning member 81 before rubbing the nozzle 51. The friction of the cleaning member 81 is reduced. When the nozzle 51 is rubbed, the nozzle 51 is prevented from being damaged. Moreover, the washing | cleaning part 82 wash | cleans the cleaning member 81 after cleaning with a cleaning liquid. The cleaning unit 82 cleans ink that has adhered to the cleaning member 81.

  The image forming apparatus 1 includes an operation panel 9. The operation panel 9 includes a display panel 91 and a touch panel 92. The operation panel 9 is provided in the control device 10 (see FIG. 6). The display panel 91 displays a setting screen and information. The display panel 91 displays operation images such as keys, buttons, and tabs. The touch panel 92 detects a touch operation on the display panel 91. Based on the output of the touch panel 92, the control unit 4 recognizes the operated operation image. The control unit 4 recognizes the setting operation performed by the user.

  Further, the image forming apparatus 1 includes a timing sensor 45. The timing sensor 45 is a sensor for determining the printing start time. The timing sensor 45 detects that the leading portion on the downstream side in the conveyance direction of the article 2 has reached a predetermined point. The control unit 4 determines the print start timing based on the leading arrival detection by the timing sensor 45.

  The communication unit 48 communicates with the computer 200. The computer 200 is, for example, a PC or a server. The communication unit 48 receives the printing data D1 from the computer 200. The control unit 4 moves the head 5 based on the printing data D1. Further, the control unit 4 causes the head 5 to eject ink based on the printing data D1.

(Head 5)
Next, an example of the head 5 according to the embodiment will be described with reference to FIGS. 3 and 4 are diagrams illustrating an example of the head 5 according to the embodiment.

  The head 5 prints the article 2. Ink is sprayed onto the printing surface 21 of the article 2. The head 5 includes a plurality of nozzles 51 arranged along the Y-axis direction. The head 5 includes several thousand nozzles 51. The length from the upper end nozzle 51 to the lower end nozzle 51 in the Y axis direction is the drawing width of the head 5 in the Y axis direction. The nozzles 51 are formed so that the intervals in the main scanning direction are uniform. Ink is ejected from the opening of the nozzle 51. A drive element 53 is provided for each nozzle 51. The drive element 53 is, for example, a piezoelectric element such as a piezo element.

  As shown in FIG. 3, the head 5 includes a plurality of driver circuits 52. The driver circuit 52 turns on / off the voltage application to each drive element 53. The control unit 4 gives the image data D2 (data indicating the nozzles 51 that should eject ink) to each driver circuit 52 for each line. The driver circuit 52 applies a pulse voltage to the drive element 53 of the nozzle 51 that should eject ink. The driving element 53 is deformed by voltage application. Deformation pressure is applied to a flow path (not shown) for supplying ink to the nozzle 51. Ink is ejected from the nozzle 51 by the pressure applied to the flow path. On the other hand, the driver circuit 52 does not apply a voltage to the drive element 53 corresponding to a pixel that does not eject ink. The driver circuit 52 actually controls ink ejection.

  The head 5 also includes a voltage generation circuit 55 that generates a plurality of types of voltages having different sizes. The driver circuit 52 applies any one of the voltages generated by the voltage generation circuit 55 to the drive element 53. The greater the applied voltage, the greater the deformation of the drive element 53. As a result, the amount of ejected ink droplets increases. The smaller the applied voltage, the smaller the deformation of the drive element 53. As a result, the amount of ejected ink droplets is reduced. The driver circuit 52 can adjust the amount of ejected ink droplets.

  As shown in FIG. 4, the nozzle 51 of the head 5 is divided into a plurality of nozzle blocks 5B. FIG. 4 shows an example in which the row nozzle 51 is divided into four blocks. The driver circuit 52 controls ink ejection from the nozzles 51 included in one nozzle block 5B.

  The control unit 4 includes a drive signal generation circuit 4a. The drive signal generation circuit 4a generates a drive signal S1. The drive signal S1 is a signal for driving the head 5. For example, the drive signal generation circuit 4a generates a clock signal. The head 5 (driver circuit 52) ejects ink each time the drive signal S1 rises once. A reference period for ink ejection is determined in advance. The control unit 4 causes the drive signal generation circuit 4a to generate a drive signal S1 having a frequency at which ink is ejected in the reference cycle.

(Moving part 6)
Next, an example of the moving unit 6 according to the embodiment will be described with reference to FIGS. FIG. 5 shows an example of the moving unit 6 according to the embodiment. FIG. 6 shows an example of the image forming apparatus 1 as viewed from above. FIG. 7 is a diagram illustrating an example of a perspective view of the image forming apparatus 1.

  The first moving mechanism 61 moves the head 5 in the Z-axis direction. The first moving mechanism 61 includes a first arm 61a. The first arm 61a is a quadrangular columnar member. The first arm 61a includes a first motor 61b, a first moving member 61c, and a first moving body 61d. The first motor 61b is, for example, a stepping motor. The first motor 61b can rotate in both the forward direction and the reverse direction. The control unit 4 controls the rotation of the first motor 61b. The first motor 61b rotates the first moving member 61c. The first moving member 61c is, for example, a ball screw. The first moving body 61d is integrated with a nut attached to the ball screw. The first motor 61b rotates the first moving member 61c. Thereby, the rotational motion of the first motor 61b is converted into a linear motion. As a result, the first moving body 61d moves in the Z-axis direction. The first arm 61a guides the movement of the first moving body 61d.

  The head 5 is attached (connected) to the first moving body 61d. The head 5 is attached to the first moving body 61d so that the nozzles 51 are arranged along the Y-axis direction (vertical direction). As the first moving body 61d moves, the head 5 moves in the Z-axis direction. By rotating the first motor 61b, the control unit 4 changes the distance between the head 5 (nozzle 51) and the article 2 (printing surface 21).

  The second moving mechanism 62 moves the head 5 in the Y-axis direction (vertical direction). The second moving mechanism 62 includes a second arm 62a. The second arm 62a is a quadrangular columnar member. The second arm 62a includes a second motor 62b, a second moving member 62c, and a second moving body 62d. The second motor 62b is, for example, a stepping motor. The second motor 62b can rotate in both the forward direction and the reverse direction. The control unit 4 controls the rotation of the second motor 62b. The second motor 62b rotates the second moving member 62c. The second moving member 62c is, for example, a ball screw. The second moving body 62d is integrated with a nut attached to the ball screw. The second motor 62b rotates the second moving member 62c. Thereby, the rotational motion of the second motor 62b is converted into a linear motion. As a result, the second moving body 62d moves. The second arm 62a guides the movement of the second moving body 62d.

  The second moving body 62d is connected to a part of the first moving mechanism 61. For example, the end of the first arm 61a in the Z-axis direction and the second moving body 62d are connected. Of the end portions of the first arm 61a in the Z-axis direction, the end portion farther from the article 2 is connected to the second moving body 62d. The head 5 moves in the Y-axis direction (height) in accordance with the movement of the second moving body 62d. By rotating the second motor 62b, the control unit 4 can change the height of the head 5 (nozzle 51).

  The third moving mechanism 63 moves the head 5 in the X-axis direction (vertical direction). As shown in FIG. 5, the third moving mechanism 63 includes a third arm 63a. The third arm 63a is a quadrangular columnar member. The third arm 63a includes a third motor 63b, a third moving member 63c, and a third moving body 63d. The third motor 63b is, for example, a stepping motor. The third motor 63b can rotate in both the forward direction and the reverse direction. The control unit 4 controls the rotation of the third motor 63b. The third motor 63b rotates the third moving member 63c. The third moving member 63c is, for example, a ball screw. The third moving body 63d is integrated with a nut attached to the ball screw. The third motor 63b rotates the third moving member 63c. Thereby, the rotational motion of the third motor 63b is converted into a linear motion. As a result, the third moving body 63d moves. The third arm 63a guides the movement of the third moving body 63d.

  The third moving body 63d is connected to a part of the second moving mechanism 62. For example, the lower end of the second arm 62a of the second moving mechanism 62 in the Y-axis direction and the third moving body 63d are connected. The head 5 moves in the X-axis direction in accordance with the movement of the third moving body 63d. The X-axis direction is also the left-right direction of the article 2 and the conveyance direction of the article 2. By rotating the third motor 63b, the control unit 4 can change the position of the head 5 in the X-axis direction.

  The control unit 4 manages and grasps the rotation speed, rotation angle, and rotation direction of the first motor 61b, the second motor 62b, and the third motor 63b. Thereby, the control unit 4 manages and recognizes the position of the head 5 in the Z-axis direction, the Y-axis direction, and the X-axis direction.

(Retraction of head 5)
Next, an example of retracting the head 5 in the image forming apparatus 1 according to the embodiment will be described with reference to FIGS. FIG. 8 is a diagram illustrating an example of a retraction flow of the head 5 in the image forming apparatus 1 according to the embodiment.

  In a state where the nozzle 51 is exposed, some components in the ink are evaporated (volatilized) from the nozzle 51. As the evaporation proceeds, the viscosity of the ink increases. When the viscosity of the ink increases, the nozzle 51 may be clogged. For example, when the nozzle 51 is left exposed, clogging occurs. The clogging is a state where ink is not ejected even when a voltage is applied to the drive element 53. In order to maintain the image quality, it is necessary to prevent clogging.

  Therefore, the image forming apparatus 1 includes a cap unit 7. The cap unit 7 is put on the exposed surface of the nozzle 51 of the head 5. The cap unit 7 prevents ink from drying. In FIG. 6, the example which provides the cap part 7 in the conveyance direction downstream of the articles | goods 2 is shown. In accordance with the head 5, the longitudinal direction of the cap portion 7 is the Y-axis direction. In the image forming apparatus 1, the cap unit 7 is provided below the rollers that constitute the conveyance line. In addition, there is no restriction | limiting in particular in the installation position of the cap part 7. FIG. The cap portion 7 can be provided at a position that does not hinder printing.

  FIG. 8 shows an example of the flow of retracting the head 5 to the cap unit 7. The start of FIG. 8 is the time when the evacuation condition is satisfied. The control unit 4 determines whether the retreat condition is satisfied. The evacuation conditions are predetermined. For example, the control unit 4 determines that the retreat condition is satisfied when the operation panel 9 receives a retreat instruction for the head 5. That is, the retreat condition may be that the user inputs to the operation panel 9 to instruct retreat of the head 5. For example, when it is predicted that printing will be stopped for a long time due to a failure in the transport line, the user inputs an evacuation instruction to the operation panel 9.

  Further, the control unit 4 may determine that the evacuation condition is satisfied when a predetermined evacuation time is reached. The evacuation time can be a time for stopping printing on the article 2. For example, the evacuation time may be a lunch break start time. Further, the evacuation time may be the closing time. The operation panel 9 accepts the setting of the evacuation time. The storage unit 43 stores the set save time. Further, the control unit 4 may determine that the evacuation condition is satisfied when a predetermined number of printings are completed. For example, when the printing of the article 2 of one lot (processing unit in the transport line) is completed, the control unit 4 determines that the retreat condition is satisfied.

  First, the control unit 4 confirms the retracted position (step # 11). The storage unit 43 stores the coordinates of the retracted position in each direction of the X axis, the Y axis, and the Z axis (see FIG. 10). The control unit 4 confirms the coordinates of the retreat position of the storage unit 43. The control unit 4 moves the head 5 to the moving unit 6 toward the retracted position (step # 12). Thereby, the head 5 is fitted into the cap portion 7 (step # 13). Then, the head 5 is maintained in a state where the ink is not dried. Then, this flow ends. When printing is started, the control unit 4 moves the head 5 to the moving unit 6 from the retracted position toward the printing position. When printing is started, the retraction of the head 5 is released.

(Cleaning the head 5)
Next, an example of the flow of cleaning the head 5 in the image forming apparatus 1 according to the embodiment will be described with reference to FIGS. FIG. 9 is a diagram illustrating an example of the flow of cleaning the head 5 of the image forming apparatus 1 according to the embodiment.

  During use, the viscosity of the ink of some nozzles 51 may increase. For example, when continuously printing images with a narrow drawing width in the Y-axis direction, the viscosity of the ink may increase at the nozzles 51 that are not used. In addition, dust and dust in the air may adhere to the nozzle 51 during use. These factors can cause clogging. In order to eliminate the clogging that has occurred, the image forming apparatus 1 has a cleaning function of the head 5 (nozzles 51).

  The image forming apparatus 1 includes a cleaning unit 8 (cleaning member 81). In FIG. 6, the example which provides the cleaning member 81 in the conveyance direction downstream of the articles | goods 2 and the upstream of the cap part 7 is shown. The arrangement direction of the nozzles 51 is parallel to the Y-axis direction. Therefore, the cleaning member 81 is installed so that the direction of the blade of the cleaning member 81 (blade) is the Y-axis direction (X-axis direction) perpendicular to the Y-axis direction. The blade direction of the blade may be parallel to the Y-axis direction. In this case, the length of the blade is equal to or greater than the length of the head. The cleaning unit 8 is provided below the rollers constituting the transport line. In addition, there is no restriction | limiting in particular in the installation position of the cleaning part 8. FIG. The cleaning unit 8 can be provided at a position that does not hinder printing.

  FIG. 9 shows an example of the flow of cleaning the head 5. The start of FIG. 9 is a point in time when a predetermined cleaning condition is satisfied. The control unit 4 determines whether or not the cleaning condition is satisfied. Cleaning conditions are predetermined. For example, the control unit 4 determines that the cleaning condition is satisfied when the operation panel 9 receives a cleaning instruction for the nozzle 51. That is, the cleaning condition may be that the user inputs to the operation panel 9 to instruct to clean the head 5.

  In addition, the control unit 4 may determine that the cleaning condition is satisfied when a predetermined cleaning time is reached. For example, the cleaning time may be a lunch break start time. Also, the cleaning time may be the closing time. The operation panel 9 accepts the setting of the cleaning time. The storage unit 43 stores the set cleaning time. Further, the control unit 4 may determine that the cleaning condition is satisfied when printing of a predetermined number of articles 2 is completed. For example, when printing for one lot (processing unit in a line) is completed, the control unit 4 determines that the cleaning condition is satisfied.

  When a predetermined number of articles 2 are printed after the start of printing or after the previous cleaning, the control unit 4 may determine that the cleaning condition is satisfied. Thus, the head 5 can be cleaned every time a certain number of prints are made. Further, the head 5 may be always cleaned before the head 5 is moved to the retracted position. In this case, the control unit 4 determines that the cleaning condition is also satisfied when the retreat condition is satisfied. Then, before the cap 5 is put on the head 5, the control unit 4 cleans the head 5.

  When the cleaning condition is satisfied (start), the control unit 4 causes the head 5 to perform a purge process (step # 21). The purge process is a process of ejecting (exuding) ink from the nozzles 51. A pump (not shown) that applies pressure to the ink flow path may be provided. The pump is provided in the ink supply path from the ink tank 11 to the head 5. The control unit 4 operates the pump during the purge process. The pump applies pressure to the ink flow path in the head 5. The cause of clogging (dust or high viscosity ink) can be discharged from the nozzle 51 by the pressure. Next, the control unit 4 causes the cleaning unit 82 to apply the cleaning liquid to the cleaning member 81 (step # 22). The control unit 4 improves the slip of the surface of the cleaning member 81.

  First, the control unit 4 confirms the cleaning start position (step # 23). The cleaning start position is the position of the head 5 where the head 5 and the tip of the blade of the cleaning member 81 are in contact. The storage unit 43 stores the coordinates of the cleaning start position in each of the X axis, Y axis, and Z axis directions (see FIG. 10). The control unit 4 confirms the coordinates of the cleaning start position in the storage unit 43. Then, the control unit 4 moves the head 5 to the moving unit 6 toward the cleaning start position (step # 24).

  Subsequently, the control unit 4 causes the moving unit 6 to perform a wiping process (step # 25). During the wiping process, the control unit 4 moves the head 5 to the moving unit 6. Specifically, the control unit 4 reciprocates the head 5 in the Y-axis direction in a state where the cleaning member 81 (blade) and the nozzle 51 are in contact with each other. When the blade direction is parallel to the Y-axis direction, the control unit 4 reciprocates the head 5 in the X-axis direction while the cleaning member 81 (blade) and the nozzle 51 are in contact with each other. The control unit 4 moves the head 5 so that all the nozzles 51 are in contact with the cleaning member 81 a plurality of times. Thereby, the nozzle 51 is rubbed with the cleaning member 81. The cleaning member 81 removes dirt from the nozzle 51. Then, this flow ends (END). When the printing is resumed after the head 5 is cleaned, the control unit 4 moves the head 5 to the moving unit 6 toward the printing position. After the head 5 is cleaned, when the cap unit 7 is put on the head 5, the control unit 4 moves the head 5 to the moving unit 6 toward the retracted position.

(Print data D1)
Next, the printing data D1 will be described with reference to FIG. FIG. 10 shows an example of the flow of input of print data D1 to the image forming apparatus 1 according to the embodiment.

  The computer 200 inputs print data D to the communication unit 48 of the image forming apparatus 1. The computer 200 can also be considered as a part of the image forming system 100.

  The computer 200 includes a processing unit 201, a computer storage unit 202, an input device 205, a display device 206, and a computer communication unit 207. The processing unit 201 is a substrate including a processing circuit such as a CPU. The computer storage unit 202 includes a ROM, a RAM, and an HDD. The computer storage unit 202 includes driver software 203 for generating print data D1. The computer storage unit 202 includes image editing software 204 for editing the image data D2 used for printing. The input device 205 is an input device such as a keyboard or a mouse. Using the input device 205, the user edits the image data D2 and inputs a print command. The display device 206 is a display. The computer communication unit 207 is an interface that communicates with the image forming apparatus 1 and other devices.

  The user creates and edits image data D2 of an image to be printed on the article 2 using the image editing software 204. For example, when printing a barcode, the user creates barcode image data D2. When printing a symbol string (character string), the user creates image data D2 of the symbol string. The image data D2 taken into the computer 200 from the outside may be used for printing the article 2. When printing a plurality of types of images on one article 2, image data D2 is generated for each image. The width of one image data D2 in the Y-axis direction is equal to or less than the drawing width of the head 5 (the width that the head 5 can draw in the Y-axis direction).

  For example, when a print command is executed by the image editing software 204, the processing unit 201 activates the driver software 203. The processing unit 201 displays a print setting screen on the display device 206 based on the driver software 203. The input device 205 receives print settings. For example, the input device 205 accepts settings of a print position (print position on the XY plane), print resolution, image type, and ejection time interval (details will be described later). For example, any one of a plurality of resolutions that can be printed by the head 5 can be selected. When printing a plurality of types of images on one article 2, it is possible to set printing for each image.

  The processing unit 201 generates print data D1 based on the driver software 203. The print data D1 includes image data D2 and print setting information D3. The processing unit 201 generates image data D2 having the selected resolution. The processing unit 201 includes the set information in the print setting information D3. For example, the processing unit 201 includes information such as a printing position, a printing resolution, an image type, and an ejection time interval (details will be described later). When printing a plurality of types of images on one article 2, the processing unit 201 can generate print data D1 for each image.

  Then, the processing unit 201 transmits the generated print data D1 to the communication unit 48 of the image forming apparatus 1. As a result, the printing data D1 is input to the image forming apparatus 1. The storage unit 43 stores the received print data D1. When printing a plurality of types of images on one article 2, the processing unit 201 can transmit print data D1 for each image. Therefore, the image forming apparatus 1 can print one article 2 based on a plurality of types of image data D2. For example, the image forming apparatus 1 can print a QR code (registered trademark) at the upper left, a symbol string at the center, and a bar code at the lower right on the printing surface 21 of the article 2.

  Only the image data D2 may be input from the computer 200. In this case, the operation panel 9 of the image forming apparatus 1 receives print settings. The control unit 4 of the image forming apparatus 1 generates print data D1.

(Movement of the head 5 in the X-axis direction and the Y-axis direction)
Next, an example of movement of the head 5 according to the embodiment in the X-axis direction will be described with reference to FIGS. FIG. 11 is a diagram illustrating an example of printing in the stopped article printing mode according to the embodiment. FIG. 12 is a diagram illustrating an example of a flow of printing in the stopped article printing mode according to the embodiment. FIG. 13 is a diagram illustrating an example of printing in the head fixing mode according to the embodiment. FIG. 14 is a diagram illustrating an example of the flow of printing in the head fixing mode according to the embodiment. FIG. 15 is a diagram illustrating an example of printing in the head movement mode according to the embodiment. FIG. 16 is a diagram illustrating an example of a printing flow for moving the head 5 according to the embodiment.

  The image forming apparatus 1 can move the head 5 in the X-axis direction (the conveyance direction of the article 2). Therefore, the image forming apparatus 1 can print the stopped article 2. The image forming apparatus 1 can also print the article 2 being conveyed. Hereinafter, the mode for printing on the stopped article 2 is referred to as a stopped article printing mode. A mode for printing the article 2 being conveyed is referred to as a conveyed article printing mode.

  The operation panel 9 can select whether to print in the stopped article printing mode or the conveyed article printing mode. The operation panel 9 accepts selection of printing in the stopped article printing mode or printing in the transported article printing mode.

1. Stop article printing mode When the conveying device 3 stops the article 2 for printing, the stop article printing mode is selected. FIG. 11 shows an example of printing in the stopped article printing mode. In FIG. 11, a cardboard box is shown as an example as the article 2. In FIG. 11, illustration of each moving mechanism and the conveyance apparatus 3 is abbreviate | omitted.

  An example of the flow of printing one article 2 in the stopped article printing mode will be described with reference to FIG. When printing the same image on the same article 2 is repeated, the process of FIG. 12 is repeated for each article 2.

  The start of FIG. 12 is a point in time when printing in the stopped article printing mode is started. For example, the conveyance device 3 stops the article 2 when a predetermined first required time elapses after the arrival of the article 2 by the timing sensor 45 is detected. The storage unit 43 stores the first required time. The first required time can be set on the operation panel 9. The controller 4 measures the first required time after the arrival of the article 2 by the timing sensor 45 is detected. The start of FIG. 12 is when the first required time has elapsed after the arrival of the article 2 by the timing sensor 45 is detected.

  First, the control unit 4 recognizes image data D2 used for printing (step # 31). When printing a plurality of images, a plurality of image data D2 are used for printing. When printing based on the image data D2, the control unit 4 moves the head 5 in the X-axis direction. The image forming apparatus 1 performs printing in units of image data D2.

  Based on the print setting information D3 corresponding to the image data D2, the control unit 4 recognizes the start head position (step # 32). When there are a plurality of image data D2, the control unit 4 determines the start head position for each image data D2. The start head position is the position of the head 5 when printing of one image is started based on the image data D2. For example, when printing a barcode image, the start head position is the position of the head 5 at the start of barcode printing.

  The control unit 4 sets positions (coordinates) on the X axis and Y axis of the head 5 as the start head position. The control unit 4 confirms the print setting information D3 corresponding to the image data D2. Then, the control unit 4 confirms the defined printing position (printing area). The control unit 4 sets the start head position in the X-axis direction so that the end of the print position in the X-axis direction and the nozzle 51 face each other. Further, the control unit 4 sets the position of the head 5 in the Y-axis direction so that the upper end and the lower end of the image are within the drawing width range of the head 5.

  Here, when printing a plurality of types of images (image data D <b> 2), the printing order can be set on the operation panel 9. Further, the control unit 4 may automatically determine the printing order of the image data D2. The control unit 4 moves the head 5 to the moving unit 6 toward the start head position corresponding to the next image (image data D2) in the printing order (step # 33). For example, the control unit 4 moves the head 5 to the moving unit 6 toward the start head position corresponding to the image to be printed first. When the printing of the first image is completed, the control unit 4 moves the head 5 to the moving unit 6 toward the start head position corresponding to the second image.

  After the movement is completed, the control unit 4 causes the head 5 to eject ink while moving the head 5 in the X-axis direction (step # 34). During ink ejection, the control unit 4 does not move the head 5 in the Y-axis direction. Thereby, an image is drawn (printed). Specifically, the control unit 4 operates the third moving mechanism 63 (third motor 63b). At this time, the control unit 4 moves the head 5 in accordance with the printing resolution. The control unit 4 recognizes the width of one dot based on the resolution of the image data D2 used for printing. Then, the control unit 4 moves the head 5 in the X-axis direction by a distance of one dot per ink discharge reference period.

  The control unit 4 confirms whether or not printing of all images in the printing surface 21 has been completed (step # 35). FIG. 11 shows a case where the interval in the Y-axis direction of the image to be printed is wider than the drawing width of the head 5. In the image forming apparatus 1, after printing the symbol string “ABCDEFGH”, the control unit 4 moves the head 5. Then, the control unit 4 causes the symbol string “IJKLMN” to be printed.

  When printing of all images has not been completed (step # 35), the flow returns to step # 33. As a result, the control unit 4 moves the head 5 to the moving unit 6 toward the start head position corresponding to the unprinted image data D2. On the other hand, when all the images have been printed (Yes in step # 35), printing on the printing surface 21 of one article 2 is completed. Upon completion of printing, this flow ends (END). The conveyance device 3 conveys the article 2 that has been printed.

2. Conveyance article printing mode When printing on the article 2 conveyed without stopping the article 2, the conveyance article printing mode is selected. In the transported article printing mode, printing can be performed while fixing the head 5 or moving the head 5 in the X-axis direction. Hereinafter, a mode for printing on the conveyed article 2 while fixing the head 5 is referred to as a head fixing mode. A mode in which the conveyed article 2 is printed while moving the head 5 in the X-axis direction is referred to as a head movement mode.

  The operation panel 9 can select whether printing is performed in the head fixing mode or the head moving mode. The operation panel 9 accepts selection of printing in the head fixing mode or printing in the head movement mode.

(1) Head fixing mode When printing on the article 2 while fixing the head 5, the head fixing mode is selected. FIG. 13 shows an example of printing in the head fixing mode. In FIG. 13, a cardboard box is shown as an example as the article 2. Moreover, in FIG. 13, illustration of each moving mechanism and the conveying apparatus 3 is abbreviate | omitted. Even in the head fixed mode, printing can be performed using a plurality of image data D2.

  An example of the flow of printing of one article 2 in the head fixing mode will be described with reference to FIG. When printing the same image on the same article 2 is repeated, the process of FIG. 14 is repeated for each article 2. The start in FIG. 14 is a point in time when printing in the head fixed mode is started.

  First, the control unit 4 selects one image data D2 from the unprinted image data D2 (step # 41). The printing order of the image data D2 (image) can be set on the operation panel 9. When printing one article 2 based on a plurality of image data D2, the control unit 4 selects the image data D2 that has not been printed and the printing order is set earlier. The control unit 4 may automatically set the printing order of the image data D2. In this case, the control unit 4 sets the order so that printing is performed earlier in the X-axis direction in the image data D2 in the downstream side in the conveyance direction of the article 2.

  Based on the print setting information D3 corresponding to the selected image data D2, the control unit 4 sets an initial head position (step # 42). The control unit 4 sets positions (coordinates) on the X axis and Y axis of the head 5 as the initial head position. The control unit 4 confirms the print setting information D3 corresponding to the image data D2. For the Y-axis direction, the control unit 4 sets the initial head position so that the upper end and the lower end of the image fall within the drawing width range of the head 5.

  As shown in FIG. 1, when the conveyance device 3 switches the conveyance direction of the article 2 by 90 degrees on the front surface of the image forming apparatus 1 (head 5), the article 2 temporarily stops on the front surface of the image forming apparatus 1 (head 5). . Then, the transport device 3 transports the article 2 along the X-axis direction. In such a case, the control unit 4 confirms the print setting information D3 corresponding to the selected image data D2. Then, the control unit 4 confirms the print position defined by the print setting information D3. The control unit 4 sets the initial head position in the X-axis direction so that the nozzle 51 faces the downstream end of the image printing position in the X-axis direction.

  In addition, the conveyance angle of the article 2 may not be switched on the front surface of the image forming apparatus 1. In other words, the image forming apparatus 1 may be provided in a section where the article 2 is continuously conveyed in a certain direction. In this case, the control unit 4 may set the position on the most upstream side in the transport direction within the movable range of the head 5 as the initial head position in the X-axis direction. The transport direction is parallel to the X-axis direction. The control unit 4 moves the head 5 to the moving unit 6 toward the set initial head position (step # 43).

  The controller 4 recognizes that the article 2 has been transported to the position where printing of the selected image data D2 is started (step # 44).

  When the conveyance device 3 switches the conveyance direction of the article 2 by 90 degrees in front of the image forming apparatus 1 (head 5), the control unit 4 has a predetermined stop waiting time after the arrival of the article 2 by the timing sensor 45 is detected. When the time has elapsed, it is recognized that the article 2 has been conveyed to the print start position. The stop waiting time is the time from when the article 2 is temporarily stopped until the article 2 starts to be transported in the X-axis direction.

  When the conveyance angle of the article 2 is not switched on the front surface of the image forming apparatus 1, the control unit 4 recognizes the first distance and the first speed. The first distance is a distance in the X-axis direction (conveyance direction) from the timing sensor 45 to the initial head position. The first distance is a fixed value. The storage unit 43 stores the first distance. The first speed is the conveyance speed of the article 2. The conveyance device 3 conveys the article 2 at a constant speed. For this reason, the first speed is determined. The first speed can be set on the operation panel 9. The storage unit 43 may store the first speed. Further, based on the output of the speed sensor 44, the control unit 4 may recognize the first speed.

  The control unit 4 recognizes the distance (second distance) in the transport direction (X-axis direction) from the downstream end of the print surface 21 in the transport direction to the position where printing is started. The controller 4 recognizes the second distance based on the image data D2. The control unit 4 obtains the start waiting time by dividing the value obtained by adding the first distance and the second distance by the first speed. The control unit 4 recognizes that the article 2 has been transported to the printing start position when the start waiting time has elapsed since the arrival of the article 2 by the timing sensor 45.

  Based on the image data D2, the controller 4 causes the head 5 to eject ink while fixing the head 5 (step # 45). Each time the article 2 is conveyed by one dot, the ink is ejected to the head 5 once.

  When the conveyance speed of the article 2 is high, the conveyance distance of the article 2 during the ink discharge reference period may exceed the width of 1 dot. In this case, the control unit 4 may shorten the cycle of the drive signal S1. That is, the control unit 4 may adjust the cycle of the drive signal S1 so that ink is ejected once every time the article 2 is conveyed by one dot. Specifically, the control unit 4 sets the period of the drive signal S1 as a time obtained by dividing the moving speed of the article 2 by the width of 1 dot. As a result, as the relative speed between the article 2 and the head 5 increases, the amount of ink discharged from the nozzle 51 to be used per unit time increases. In addition, as the relative speed between the article 2 and the head 5 is lower, the amount of ink discharged from the nozzle 51 to be used per unit time becomes smaller.

  Further, the control unit 4 may perform printing while maintaining the cycle of the drive signal S1 at the reference cycle. In this case, the control unit 4 obtains the actual movement distance of the article 2 during the reference period. The actual moving distance is the actual width of one dot when ink is ejected at the reference period. The control unit 4 multiplies the actual conveyance speed of the article 2 by the reference period. The control unit 4 obtains the resolution of the image to be printed based on the actual moving distance. When the resolution of the image data D2 does not match the resolution of the image to be printed, the control unit 4 performs image processing for matching the resolution on the image data D2. For example, the control unit 4 thins out lines from the image data D2. For example, it is assumed that the article 2 is conveyed by 2 dots in the image data D2 during the reference period. In this case, the control unit 4 thins out 1/2 of the line of the image data D2. As a result, the size of the printed image becomes the size desired by the user.

  As the number of lines decreases, the printed image may become lighter. Therefore, the control unit 4 may increase the amount of ink droplets. Specifically, when the resolution of the image data D2 is lowered, the control unit 4 increases the voltage applied to the drive element 53 as compared with the case where the resolution of the image data D2 is not lowered. As a result, as the relative speed between the article 2 and the head 5 increases, the amount of ink discharged from the nozzle 51 to be used per unit time increases.

  In this way, an image is drawn on the printing surface 21 of the article 2. Then, printing based on one image data D2 is completed (step # 46). Subsequently, the control unit 4 confirms whether or not printing of all images within the printing surface 21 has been completed (step # 47). When printing of all images is completed (Yes in step # 47), printing on the printing surface 21 of one article 2 is completed. Upon completion of printing, this flow ends (END).

  When printing of all images has not been completed (No in step # 47), the control unit 4 selects the next sequential image data D2 from the unprinted image data D2 (step # 48). Next, based on the print setting information D3 corresponding to the selected image data D2, the control unit 4 sets the next head position (step # 49).

  The control unit 4 sets the position (coordinates) on the X axis and Y axis of the head 5 as the next head position. For the Y-axis direction, the control unit 4 sets the next head position so that the upper end and lower end of the image are within the drawing width range of the head 5.

  For example, the control unit 4 obtains the third distance. The third distance is the distance between the print end position in the X-axis direction of the image data D2 selected immediately before and the print start position in the X-axis direction in the image data D2 selected this time. The print end position is an end on the upstream side in the conveyance direction of the image. The print start position is the downstream end in the image transport direction. The control unit 4 obtains the third distance by multiplying the number of pixels in the X-axis direction from the pixel at the print end position to the print start position by the width of one dot.

(1) When the print start position of the currently selected image data D2 is on the upstream side in the transport direction with respect to the print end position of the previously selected image data D2, the control unit 4 is one in the X-axis direction. A position that is a third distance away from the printing end position of the previously selected image data D2 upstream in the transport direction is set as the next head position.
(2) When the print start position of the currently selected image data D2 is on the downstream side of the print end position of the image data D2 selected immediately before The control unit 4 moves forward by one in the X-axis direction. A position separated by a third distance from the printing end position of the selected image data D2 on the downstream side in the transport direction is set as the next head position.

  The control unit 4 moves the head 5 to the moving unit 6 toward the set next head position (step # 410). It takes a certain amount of time to move to the next head position. Therefore, the control unit 4 may adjust the position of the head 5 in the X-axis direction. For example, the control unit 4 measures the first time from the start to the end of the movement to the next head position. And the control part 4 calculates | requires 4th distance by multiplying 1st time and 1st speed. As the position adjustment in the X-axis direction, the head 5 is further moved in the X-axis direction by the fourth distance. After the movement, the control unit 4 discharges ink to the head 5 while fixing the head 5 based on the image data D2 (step # 411). Eventually, printing based on one image data D2 is completed (step # 412). Then, the flow returns to step # 47. Finally, all the images are printed on the printing surface 21 of the article 2.

(2) Head Movement Mode When printing on the conveyed article 2 while moving the head 5 in the X-axis direction, the head movement mode is selected. FIG. 15 shows an example of printing in the head movement mode. In FIG. 15, a cardboard box is shown as an example as the article 2. Moreover, in FIG. 15, illustration of each moving mechanism and the conveying apparatus 3 is abbreviate | omitted. Even in the head movement mode, printing can be performed using a plurality of image data D2.

  An example of the printing flow of one article 2 in the head movement mode will be described with reference to FIG. When printing the same image on the same article 2 is repeated, the process of FIG. 16 is repeated for each article 2. The start in FIG. 16 is a point in time when printing in the head movement mode is started.

  First, the control unit 4 selects one image data D2 from the unprinted image data D2 (step # 51). The printing order of the image data D2 (image) can be set on the operation panel 9. When printing one article 2 based on a plurality of image data D2, the control unit 4 selects the image data D2 that has not been printed and the printing order is set earlier. The control unit 4 may automatically set the printing order of the image data D2. In this case, the control unit 4 sets the order so that printing is performed earlier in the X-axis direction in the image data D2 in the downstream side in the conveyance direction of the article 2.

  Based on the print setting information D3 corresponding to the selected image data D2, the control unit 4 sets an initial head position (step # 52). The control unit 4 sets positions (coordinates) on the X axis and Y axis of the head 5 as the initial head position. Since the method of setting the initial head position is the same as that in the head fixing mode (step # 42), description thereof is omitted. Then, the control unit 4 moves the head 5 to the moving unit 6 toward the set initial head position (step # 53).

  Then, the control unit 4 recognizes that the article 2 has been transported to a position where printing of the selected image data D2 is started (step # 54). Since step # 54 is the same as step # 44, description thereof is omitted. When the article 2 is conveyed to a position where printing is started, the control unit 4 causes the head 5 to eject ink while moving the head 5 based on the image data D2 (step # 55).

  At this time, the control unit 4 moves the head 5 to the moving unit 6 so that the relative speed between the moving speed (first speed) of the article 2 and the moving speed of the head 5 is constant based on the output of the speed sensor 44. Let When the relative speed is not constant, the width of one dot will change during printing.

  Here, when the conveyance distance in the reference period exceeds one dot width in the resolution of the image data D2, the control unit 4 moves the head 5 in the X axis direction in the direction following the article 2 (downstream in the conveyance direction). Is moved to the moving unit 6. The control unit 4 moves the head 5 to the moving unit 6 along the X-axis direction so that the relative speed between the article 2 and the head 5 is a speed obtained by dividing the one-dot width by the ink discharge reference period. In this case, the control unit 4 recognizes the first speed (the moving speed of the article 2 in the X-axis direction). For example, based on the output of the speed sensor 44, the control unit 4 recognizes the first speed. The control unit 4 obtains the moving distance of the article 2 during the reference period based on the recognized first speed (reference period × first speed). Further, the control unit 4 recognizes the 1-dot width based on the resolution (printing resolution) of the image data D2. The control unit 4 moves the head 5 in the X-axis direction at a speed obtained by dividing the absolute value of the difference between the moving distance and 1 dot by the reference period. The control unit 4 causes the head 5 to eject ink at a reference period. As a result, an image having a resolution and size desired by the user is printed.

  Even if the head 5 is moved at the maximum speed in the X-axis direction, the delay of the head 5 per reference period with respect to the article 2 may exceed the width of one dot. In this case, the control unit 4 may make the cycle of the drive signal S1 shorter than the reference cycle. The control unit 4 may adjust the frequency of the drive signal S1 so that the ink is ejected once every time the article 2 and the head 5 are delayed by one dot.

  Alternatively, the control unit 4 may perform printing while maintaining the cycle of the drive signal S1 at the reference cycle. In this case, the control unit 4 obtains the delay of the head 5 with respect to the article 2 during the reference period. For example, the control unit 4 multiplies the speed difference between the actual conveyance speed of the article 2 and the maximum movement speed of the head 5 by the reference period. Based on the obtained delay, the control unit 4 obtains the resolution of the actually printed image. When the resolution of the image data D2 does not match the resolution of the actually printed image, the control unit 4 performs image processing for matching the resolution of the image data D2 with the resolution of the actually printed image. For example, the control unit 4 thins out lines from the image data D2.

  As the number of lines decreases, the printed image may become lighter. Therefore, when the line is thinned out from the image data D2, the control unit 4 may increase the amount of ink per droplet. Specifically, when the resolution of the image data D2 is reduced, the control unit 4 increases the voltage applied to the drive element 53 than before the resolution of the image data D2 is reduced. As a result, as the relative speed between the article 2 and the head 5 increases, the amount of ink discharged from the nozzle 51 to be used per unit time increases. In addition, as the relative speed between the article 2 and the head 5 is lower, the amount of ink discharged from the nozzle 51 to be used per unit time becomes smaller.

  As a result, an image is drawn on the printing surface 21 of the article 2. Then, printing based on one image data D2 is completed (step # 56). Subsequently, the control unit 4 confirms whether or not printing of all images in the printing surface 21 has been completed (step # 57). When printing of all images is completed (Yes in step # 57), printing on the printing surface 21 of one article 2 is completed. Upon completion of printing, this flow ends (END).

  When printing of all images has not been completed (No in step # 57), the control unit 4 selects the next sequential image data D2 from the unprinted image data D2 (step # 58). Next, based on the print setting information D3 corresponding to the selected image data D2, the control unit 4 sets the next head position (step # 59).

  The control unit 4 sets the position (coordinates) on the X axis and Y axis of the head 5 as the next head position. For the Y-axis direction, the control unit 4 sets the next head position so that the upper end and lower end of the image are within the drawing width range of the head 5.

  For example, the control unit 4 obtains the third distance. The third distance is the distance between the print end position in the X-axis direction of the image data D2 selected immediately before and the print start position in the X-axis direction in the image data D2 selected this time. In the head movement mode, the print end position is the upstream end in the transport direction of the image corresponding to the image data D2 selected immediately before. The print start position is an end on the downstream side in the transport direction among images to be printed based on the image data D2 selected this time. For example, the control unit 4 obtains the third distance by multiplying the number of pixels in the X-axis direction from the pixel at the print end position to the print start position by the width of one dot.

(1) When the print start position of the image data D2 selected this time is upstream of the print end position of the image data D2 selected immediately before The control unit 4 is upstream in the transport direction from the current position in the X-axis direction. The position separated by the third distance on the side is set as the next head position.
(2) When the print start position of the image data D2 selected this time is on the downstream side of the print end position of the image data D2 selected immediately before The control unit 4 is downstream in the transport direction from the current position in the X-axis direction. The position separated by the third distance on the side is set as the next head position.

  The control unit 4 moves the head 5 to the moving unit 6 toward the set next head position (step # 510). Note that it takes some time for the head 5 to move to the next head position. Therefore, the control unit 4 may adjust the position of the head 5 in the X-axis direction. For example, the control unit 4 measures the first time from the start to the end of the movement to the next head position. And the control part 4 calculates | requires 4th distance by multiplying 1st time and 1st speed. As the position adjustment in the X-axis direction, the head 5 is further moved in the X-axis direction by the fourth distance. Based on the image data D2, the control unit 4 causes the head 5 to eject ink while moving the head 5 in the X-axis direction (step # 511). Eventually, printing based on one image data D2 is completed (step # 512). Then, the flow returns to step # 57. Finally, all the images are printed on the printing surface 21 of the article 2.

(Setting of the interval between the nozzle 51 and the printing surface 21)
Next, an example of setting the interval between the nozzle 51 and the printing surface 21 according to the embodiment will be described with reference to FIGS. FIG. 17 is a diagram illustrating an example of the transport device 3 according to the embodiment. FIG. 18 shows an example of the definition data D4 according to the embodiment. FIG. 19 shows an example of the image type selection screen 93 according to the embodiment. FIG. 20 shows an example of the smoothing level selection screen 94 according to the embodiment.

  The image forming apparatus 1 can move the head 5 in the Z-axis direction (the conveyance direction of the article 2). Therefore, the image forming apparatus 1 can adjust the interval between the printing surface 21 and the nozzles 51. The control unit 4 sets an ejection time interval according to the image to be printed or the article 2. The discharge interval is the interval between the nozzle 51 and the printing surface 21 during ink discharge. The control unit 4 moves the head 5 to the moving unit 6 in the Z-axis direction so that the set discharge time interval is reached. A plurality of discharge interval setting methods are prepared.

  First, the conveyance of the article 2 by the conveyance device 3 will be described with reference to FIGS. The conveyance device 3 includes a conveyance control device 30, a drive source 31, a conveyance member 32, a conveyance guide 33, and a position adjustment device 34. The conveyance control device 30 controls the operation of members related to the conveyance of the article 2. The conveyance control device 30 includes a CPU, a memory, an interface unit, and other circuits. The memory stores data and programs related to article conveyance. The conveyance control device 30 conveys the article 2 based on memory data and programs. The interface unit is a circuit and a connector for communicating with the drive source 31 and the position adjusting device 34.

  The drive source 31 is a power source that rotates the transport member 32. The drive source 31 is, for example, a motor. The conveying member 32 is a member that conveys the article 2. The conveying member 32 is a rotating body. For example, the conveying member 32 is a roller or a belt. When the conveying member 32 is a roller, the conveying device 3 includes a plurality of rollers. The axial direction of each roller is perpendicular to the transport direction. The conveying member 32 is in contact with the article 2. In the example of FIG. 7, an example in which the article 2 is placed on the conveying member 32 is shown. The article 2 is conveyed by the conveyance member 32 rotating.

  The conveyance guide 33 is a member that guides the article 2 to be conveyed. In the example of FIG. 7, an example in which the conveyance guide 33 is provided at a position in contact with the lower end of the article 2 is shown. FIG. 7 shows an example in which a conveyance guide 33 is provided above the conveyance member 32. The lower end of the printing surface 21 of the article 2 is in contact with the conveyance guide 33. The longitudinal direction of the transport guide 33 is parallel to the transport direction (X-axis direction) of the article 2.

  The position adjusting device 34 is a mechanism for adjusting the position of the article 2. The position adjusting device 34 pushes the article 2. The position adjusting device 34 pushes the back surface of the printing surface 21 of the article 2. In other words, the position adjusting device 34 moves the article 2 in a direction in which the printing surface 21 approaches the image forming apparatus 1. The position adjustment device 34 moves the position of the article 2 so that the conveyance guide 33 and the lower end of the printing surface 21 of the article 2 are in contact with each other. The guide direction of the conveyance guide 33 is parallel to the X-axis direction. Therefore, when the article 2 is a cube or a rectangular parallelepiped, the printing surface 21 of the article 2, the X axis, and the Y axis are parallel. Accordingly, the nozzle 51 faces the printing surface 21 of the article 2. Further, the Z axis is perpendicular to the printing surface 21 of the article 2. In FIG. 7, the position adjusting device 34 is invisible.

  The conveyance device 3 includes a conveyance guide 33 and a position adjustment device 34. Therefore, when the image forming apparatus 1 performs printing, the conveying device 3 sets the printing surface 21 of the article 2 as a reference position. In other words, the conveying device 3 makes the position of the printing surface 21 of the article 2 before printing constant. The reference position of the printing surface 21 is a position where the conveyance guide 33 and the article 2 are in contact with each other.

1. Setting the interval based on the print setting information D3 The control unit 4 can set the discharge time interval based on the print setting information D3. The print setting information D3 is included in the print data D1. The print setting information D3 is associated with image data D2 used for image printing.

  The print setting information D3 includes information set on the driver software 203 of the computer 200. When the print setting information D3 includes information indicating the image type, the control unit 4 can set the ejection time interval based on the image type defined by the print setting information D3. In addition, when using several image data D2 for printing of the one article | item 2, the control part 4 sets the discharge time space | interval for every image data D2.

  In order to set the ejection time interval according to the type of image, the definition data D4 may be stored in the storage unit 43 in a nonvolatile manner (see FIG. 10). The definition data D4 is data that defines an ejection time interval for each type of image. FIG. 18 shows an example of the definition data D4. In the definition data D4 of FIG. 18, when the image type is a symbol string, the discharge interval is defined as 5 mm. The symbols include letters and numbers. The symbol string includes, for example, a company name, a mail address, a telephone number, and date / time. The symbol string is mainly composed of letters and numbers, and the letters and numbers are arranged.

  In the definition data D4 in FIG. 18, when the image type is a two-dimensional code, the discharge time interval is defined as 1 mm. The two-dimensional code is, for example, a QR code (registered trademark). Further, in the definition data D4 of FIG. 18, when the image type is a one-dimensional code, the discharge interval is defined as 3 mm. The one-dimensional code is, for example, a barcode. The definition data D4 may include definitions of image types other than the two-dimensional code, the one-dimensional code, and the symbol string, and the ejection time interval.

  The wider the distance between the printing surface 21 and the nozzle 51, the longer the time from ejection to landing. The longer the time from ejection to landing, the greater the effect of gravity and air flow on ink droplets. For this reason, as the distance between the printing surface 21 and the nozzle 51 increases, the ink landing position tends to deviate from the target position. As the distance between the printing surface 21 and the nozzle 51 is narrower, a more precise image can be printed.

  Therefore, the definition data D4 may be defined so that the more precisely the image to be printed, the narrower the discharge time interval. For example, the two-dimensional code includes dots. Based on the size of the dot (block), information included in the code is obtained. When the dot boundary is not clear or the dot size is inappropriate, information may not be correctly read from the two-dimensional code. Therefore, when the image type is a two-dimensional code, the definition data D4 is defined so that the discharge time interval is at the minimum level.

  When the distance between the printing surface 21 and the nozzle 51 is narrow, the article 2 easily collides with the nozzle 51. The printing surface 21 of the article 2 is not necessarily flat. For example, there are some irregularities in the packing box. The position of the article 2 is adjusted. However, the possibility that the article 2 and the nozzle 51 come into contact with each other is not zero. If contact of the printing surface 21 with the nozzle 51 is repeated, the nozzle 51 (head 5) may be broken. From the standpoint of preventing contact, it is preferable that the distance between the printing surface 21 and the nozzle 51 is increased.

  Therefore, in the definition data D4, the discharge time interval may be set wider for images with less need for precise printing. For example, a symbol string (character string) has many solid portions. There is no problem even if the ink landing position is slightly deviated. FIG. 18 shows an example of definition data D4 for widening the ejection time interval when the image type is a symbol string. The one-dimensional code is scanned. For this reason, the one-dimensional code needs to be printed with a certain degree of precision. On the other hand, the primary code does not require as precise printing as the two-dimensional code. FIG. 18 shows an example of definition data D4 in which the discharge time interval is narrower than the symbol string and the discharge time interval is wider than the two-dimensional code when the image type is a one-dimensional code.

  The print setting information D3 may include information (value) indicating the discharge time interval. In this case, the input device 205 of the computer 200 accepts numerical input of the discharge time interval. Based on the driver software 203, the processing unit 201 generates print setting information D3 (print data D1) including a discharge time interval that is numerically input. When the print setting information D3 associated with the image data D2 includes information indicating the value of the discharge time interval, the control unit 4 sets the discharge time interval based on the value included in the print setting information D3.

2. Setting of the discharge time interval based on the image data D2 The control unit 4 may set the discharge time interval based on the image data D2. In this case, the control unit 4 analyzes the image data D2. Then, the control unit 4 determines the type of image included in the image data D2. Then, the control unit 4 may set the ejection time interval based on the determined image type and the definition data D4. In addition, when using several image data D2 for printing of the one article | item 2, the control part 4 determines the kind of image for every image data D2. The control unit 4 sets an ejection time interval for each image data D2.

  For example, the control unit 4 checks whether or not the image included in the image data D2 is a two-dimensional code image. For example, the control unit 4 confirms whether or not a graphic required by the two-dimensional code standard is included in the image data D2. When the essential graphic is included, the control unit 4 determines that the type of the image is a two-dimensional code. Further, the control unit 4 confirms whether or not the image included in the image data D2 is a one-dimensional code image. For example, the control unit 4 confirms whether or not the image data D2 includes the number of parallel straight lines determined by the standard of the one-dimensional code. When the number of parallel straight lines defined by the standard is included, the control unit 4 determines that the type of image is a one-dimensional code. When the image data D2 does not include a two-dimensional code and does not include a one-dimensional code, the control unit 4 may determine that the image type is a symbol string. The control unit 4 sets an ejection time interval based on the determined image type and definition data D4.

3. Setting of the discharge time interval by the operation panel 9 The operation panel 9 may accept selection of the type of image to be printed. When a predetermined operation is performed, the control unit 4 displays an image type selection screen 93 on the display panel 91. The user touches the screen to select the image type. When using a plurality of image data D2 for printing one article 2, the operation panel 9 accepts selection of an image type for each image data D2. The control unit 4 sets an ejection time interval for each image data D2.

  FIG. 19 shows an example of the image type selection screen 93. In the image type selection screen 93 shown in FIG. 19, one of the three types can be selected. A first selection button B 1, a second selection button B 2, and a third selection button B 3 are displayed in the image type selection screen 93. When the image is a symbol string, the user operates the first selection button B1. When the image is a one-dimensional code, the user operates the second selection button B2. When the image is a two-dimensional code, the user operates the third selection button B3.

  In the definition data D4, an ejection time interval is determined for each type of image that can be selected. For example, the discharge interval of the symbol string image is 5 mm. The discharge interval of the one-dimensional code image is 3 mm. The discharge time interval of the two-dimensional code image is 1 mm. The control unit 4 sets the discharge time interval based on the image type selected on the operation panel 9 and the definition data D4. In the image forming apparatus 1, there are a symbol string, a one-dimensional code, and a two-dimensional code as selectable image types. Further, another image type may be selected. When the symbol string is selected, the control unit 4 sets the discharge time interval to the first interval. When the one-dimensional code is selected, the control unit 4 sets the discharge interval to a second interval that is narrower than the first interval. When the two-dimensional code is selected, the discharge interval is set to a third interval that is narrower than the second interval. As long as the relationship of the first interval> the second interval> the third interval is maintained, the first interval may be other than 5 mm. Similarly, the second interval may be other than 3 mm. The third interval may be other than 1 mm.

4). The article 2 conveyed on the setting line (conveying device 3) of the discharge time interval based on the smoothness level of the surface of the article 2 may change. That is, the article 2 printed by the image forming apparatus 1 may change. For example, the print target may change in lot units. The paper quality and size of the cardboard box to be printed may vary from lot to lot. The article 2 having a smooth surface (clogged) may be printed, or the article 2 having a rough surface (grainy) may be printed.

  The rougher the surface, the more ink is blotted. On the other hand, when the surface is rough, an image with less unevenness may be printed by intentionally shifting the ink landing position. This is because the ink can be soaked into fine dents on the surface of the article 2. In addition, the smoother the surface of the article 2, the more noticeable deviation of the ink landing position may be.

  Therefore, the operation panel 9 may accept the setting of the smoothness level of the surface of the article 2. When a predetermined operation is performed, the control unit 4 causes the display panel 91 to display the smoothing level selection screen 94. The user touches the screen and selects the state of the printing surface 21 of the article 2.

  FIG. 20 shows an example of the smoothing level selection screen 94. On the smoothing level selection screen 94 shown in FIG. 20, one can be selected from among three types. A fourth selection button B4, a fifth selection button B5, and a sixth selection button B6 are displayed in the smoothing level selection screen 94. The user who thinks that the smoothness level of the surface of the article 2 is high (smooth) operates the fourth selection button B4. A user who thinks that the smoothness level of the surface of the article 2 is normal operates the fifth selection button B5. A user who thinks that the smoothness level of the surface of the article 2 is low (rough) operates the sixth selection button B6.

  The discharge time interval is determined in advance for each smooth level selected. In other words, the discharge time interval corresponding to the selection button is predetermined. For example, the discharge time interval corresponding to the sixth selection button B6 is 5 mm. The discharge time interval corresponding to the fifth selection button B5 is 3 mm. The discharge time interval corresponding to the fourth selection button B4 is 1 mm. The control unit 4 sets the discharge time interval according to the smoothing level selected on the operation panel 9. The controller 4 narrows the discharge time interval as the set smoothing level is higher. The controller 4 narrows the discharge time interval as the set smoothing level is lower.

(Moving control of the head 5 in the Z-axis direction)
Next, an example of movement control in the Z-axis direction of the head 5 according to the embodiment will be described with reference to FIG. FIG. 21 is a diagram illustrating an example of the flow of movement of the head 5 according to the embodiment in the Z-axis direction.

  The start in FIG. 21 is a point in time when printing is started. In other words, it is the time when the conveyance of the article 2 to be printed on the line (conveyance device 3) is started. When printing on a plurality of articles 2 continuously, it is the time when printing on the first article 2 is started. When printing the same image continuously on the same article 2 in lot units (minimum production unit), it is the time when printing on the first article 2 is started.

  First, the control unit 4 sets the position of the head 5 in the Z-axis direction as a collision avoidance position (step # 61). The control unit 4 moves the head 5 to a collision avoidance position. The collision avoidance position is a position where the nozzle 51 is sufficiently separated from the printing surface 21. Even if the article 2 is shaken, the article 2 and the nozzle 51 are not in contact with each other. The collision avoidance position can be determined as appropriate. The collision avoidance position may be a position where the interval between the nozzle 51 and the printing surface 21 in the Z-axis direction is about two to several times the maximum value of the discharge time interval.

  Subsequently, the control unit 4 recognizes the image data D2 used for printing (step # 62). When printing the article 2 using a plurality of image data D2, the control unit 4 sets an ejection time interval for each image data D2. Here, the control unit 4 can set the ejection time interval by selecting the print setting information D3, the image data D2, and the operation panel 9. The control unit 4 gives priority to the selection on the operation panel 9 even if the image type is selected in the print setting information D3.

  Specifically, the user performs selection on the image type selection screen 93 or the smoothing level selection screen 94 and sets the discharge time interval. The transmission of the printing data D1 from the computer 200 to the image forming apparatus 1 and the setting on each selection screen are performed before the conveying device 3 starts conveying the article 2. When selection is performed on both the image type selection screen 93 and the smoothing level selection screen 94, the control unit 4 may prioritize selection on the image type selection screen 93. In this case, the control unit 4 sets an ejection time interval corresponding to the button selected on the image type selection screen 93. Further, selection on the smoothing level selection screen 94 may be prioritized. In this case, the control unit 4 sets an ejection time interval corresponding to the button selected on the smoothing level selection screen 94.

  When there is no selection on each selection screen, the control unit 4 sets an ejection time interval for each image data D2 based on the print setting information D3. Even if it does not select with the operation panel 9, the control part 4 sets the discharge time interval automatically for every image data D2. When the print setting information D3 does not include information indicating the type of image or a value indicating the ejection time interval, the control unit 4 analyzes the image data D2 and sets the ejection time interval.

  The controller 4 starts recognizing the interval between the nozzle 51 and the printing surface 21 based on the output of the interval sensor 46 (step # 63). After the arrival of the article 2 by the timing sensor 45, the control unit 4 starts to recognize the interval when the printing surface 21 of the article 2 comes to the front surface of the interval sensor 46 (head 5).

  When the conveyance device 3 switches the conveyance direction of the article 2 by 90 degrees on the front surface of the image forming apparatus 1 (head 5), the control unit 4 waits for a stop waiting time after the arrival of the article 2 by the timing sensor 45. Start interval recognition.

  When the conveyance angle of the article 2 is not switched on the front surface of the image forming apparatus 1, the control unit 4 starts to recognize the interval after waiting for the arrival waiting time after the arrival of the article 2 by the timing sensor 45 is detected. The arrival waiting time is a time obtained by dividing the distance in the X-axis direction from the timing sensor 45 to the head 5 at the collision avoidance position by the conveyance speed of the article 2.

  Then, the control unit 4 performs alignment processing before starting printing of one image (image data D2) (step # 64). During the alignment process, the control unit 4 moves the head 5 to the moving unit 6 in the Z-axis direction. Then, the control unit 4 sets the interval between the nozzle 51 and the printing surface 21 as a discharge interval. Specifically, the control unit 4 moves the head 5 to the moving unit 6 so that the interval detected by the interval sensor 46 becomes the ejection interval. The control unit 4 brings the head 5 close to the article 2.

  Eventually, printing of one image by the head 5 is started (step # 65). During printing of the image, the control unit 4 moves the head 5 to the moving unit 6 in the Z-axis direction so that the interval is kept constant (step # 66). The controller 4 keeps the interval at the discharge time interval. During printing, the control unit 4 continues to monitor the output of the interval sensor 46. When the recognized interval deviates from the discharge interval, the control unit 4 moves the head 5 to the moving unit 6 in the Z-axis direction. In other words, the control unit 4 performs feedback control based on the output of the interval sensor 46 so that the interval is maintained at the discharge time interval. The control unit 4 causes the position of the head 5 in the Z-axis direction to follow the unevenness of the printing surface 21 of the article 2. Even if the printing surface 21 of the article 2 is uneven, the nozzle 51 and the article 2 do not collide. Eventually, printing of one image is completed (step # 67).

  Then, the control unit 4 checks whether or not all images have been printed on the printing surface 21 (step # 68). In other words, the control unit 4 confirms whether printing of one article 2 is completed. When all the images have not been printed on the printing surface 21 (No in Step # 68), the control unit 4 determines whether the difference between the discharge time interval corresponding to the next image to be printed and the current interval is within the allowable range. Whether or not is confirmed (step # 69). The allowable range is predetermined.

  The allowable range can be, for example, 1 to several mm. When the difference is outside the allowable range (No in step # 69), it is necessary to perform alignment processing before starting the printing of the next image. Therefore, when the difference is outside the allowable range (No in step # 69), the flow returns to step # 64. In this case, the control unit 4 recognizes the ejection time interval corresponding to the image data D2 of the image to be printed next. The control unit 4 sets an interval between the nozzle 51 and the printing surface 21 as an ejection time interval corresponding to an image to be printed next.

  On the other hand, when the difference is within the allowable range (Yes in step # 69), it is less necessary to perform the alignment process before starting the printing of the next image. Therefore, when the difference is within the allowable range (No in step # 69), the flow returns to step # 65. That is, when the difference is within the allowable range, the control unit 4 skips the alignment process in the Z-axis direction.

  When all the images have been printed on the printing surface 21 (Yes in Step # 68), the control unit 4 stops recognizing the interval (Step # 610). Subsequently, it is confirmed whether or not the next article 2 is to be printed (step # 611). In other words, the control unit 4 confirms whether or not printing of the article 2 for one lot has been completed (step # 611). When the next article 2 is printed (Yes in step # 611), the flow returns to step # 61. That is, the control unit 4 returns the position of the head 5 in the Z-axis direction to the collision avoidance position. When there is no next article 2 to be printed, this flow ends (END). Thereafter, for example, the cleaning of the head 5 and the movement of the head 5 to the cap portion 7 are performed.

(Adjustment of ink discharge amount according to discharge interval)
Next, an example of adjusting the ink discharge amount in the image forming apparatus 1 according to the embodiment will be described with reference to FIG. FIG. 22 is a diagram illustrating an example of the ink discharge amount data D5 according to the embodiment.

  The image forming apparatus 1 can move the head 5 in the Z-axis direction. Therefore, the interval between the nozzle 51 and the printing surface 21 can be freely changed. This is different from a printing apparatus installed on a conventional transport line. Here, the shorter the ejection interval, the easier it is for the ink to land at the target position. On the other hand, the wider the ejection interval, the easier the actual ink landing position will deviate from the target position. For example, ink may land on dots that are not colored on the image data D2. Depending on the image, the printed image may appear to have a reduced density.

  Therefore, the control unit 4 causes the head 5 to decrease the ink discharge amount per dot as the discharge time interval is narrower. The control unit 4 causes the head 5 to increase the ink discharge amount per dot as the discharge interval is wider.

  The head 5 includes a voltage generation circuit 55 (see FIG. 3). The voltage generation circuit 55 generates a plurality of types of voltages. The voltage generation circuit 55 generates a voltage having a preset magnitude. A voltage to be applied to the drive element 53 can be selected from a plurality of types of voltages generated by the voltage generation circuit 55. That is, the voltage applied to the drive element 53 can be changed.

  The amount of deformation of the drive element 53 varies depending on the magnitude of the voltage applied to the drive element 53. The pressure applied to the ink flow path changes according to the deformation amount of the drive element 53. Therefore, the control unit 4 (driver circuit 52) can change the amount of ejected ink (droplet) by selecting the magnitude of the voltage applied to the drive element 53.

  FIG. 22 is a diagram illustrating an example of the ink discharge amount data D5 according to the embodiment. The storage unit 43 stores ink discharge amount data D5 in a nonvolatile manner. The ink discharge amount data D5 is defined so that the ink discharge amount per dot decreases as the discharge interval decreases. Further, it is defined that the larger the ejection time interval, the larger the ink ejection amount per dot.

  FIG. 22 shows an example in which the discharge time interval is classified into three ranges. The voltage generation circuit 55 shows an example in which at least three types of voltages can be generated. In FIG. 22, there is a relationship of voltage V1 <voltage V2 <voltage V3. Therefore, the ink discharge amount (droplet amount) has a relationship of first discharge amount a1 <second discharge amount a2 <third discharge amount a3.

  According to the ink discharge amount data D5 of FIG. 22, when the discharge time interval is 1 mm, the control unit 4 applies the voltage V1 to the drive element 53. Then, the control unit 4 sets the amount of ink ejected from the nozzle 51 as the first ejection amount a1. Further, when the discharge time interval is 3 mm, the control unit 4 applies the voltage V <b> 2 to the drive element 53. The control unit 4 sets the amount of ink ejected from the nozzle 51 as the second ejection amount a2. When the discharge time interval is 5 mm, the control unit 4 applies the voltage V3 to the drive element 53. Then, the control unit 4 sets the amount of ink ejected from the nozzle 51 as the third ejection amount a3. The control unit 4 refers to the ink discharge amount data D5. Then, the control unit 4 causes the head 5 to eject ink according to the set ejection time interval.

  The ink discharge amount per dot may be adjusted by other methods. For example, the control unit 4 may change the timing (number of times) of ejecting ink to one dot according to the ejection time interval. For example, when the ejection time interval is 0 <W ≦ 2 mm, the control unit 4 may eject ink twice per dot. Further, when the ejection time interval is 2 mm <W ≦ 4 mm, the control unit 4 may eject ink three times for one dot. Further, when the discharge time interval is 4 mm <W, the control unit 4 may discharge ink four times for one dot. In order to eject ink at high speed, the control unit 4 may increase the frequency of the drive signal S1 as the ejection time interval increases.

(Change of nozzle 51 to be used)
Next, an example of a process for changing the nozzle 51 used in the head 5 according to the embodiment will be described with reference to FIGS. 23 and 24 are diagrams illustrating an example of a change process of the nozzle 51 used in the image forming apparatus 1 according to the embodiment.

  The image forming apparatus 1 is installed on the conveyance line. The same product 2 (same product) may be continuously flowed to the transport line. For example, in a factory, the articles 2 having the same specifications in lot units are flowed on the transport line. A lot means a minimum processing (production) unit. In this case, the image forming apparatus 1 repeatedly prints the same image. Hereinafter, images that are repeatedly printed at the same position in the plurality of articles 2 are referred to as “repeated images”. When one lot is 1000 pieces, the image forming apparatus 1 prints an image repeatedly 1000 times.

  The nozzles 51 are arranged along the Y-axis direction (the vertical direction of the article 2). The control unit 4 fixes the position of the head 5 in the Y-axis direction during ink ejection to the moving unit 6. The control unit 4 makes the position of the head 5 in the Y-axis direction during ink ejection constant in a plurality of articles. When printing repeated images, the control unit 4 sets a Y-axis fixed position for each repeated image. During the ejection of ink for repeatedly printing images, the control unit 4 fixes the position of the head 5 in the Y-axis direction at the Y-axis fixed position. For example, it is assumed that the number of nozzles required for printing the repeated image A is 500. In this case, the control unit 4 repeatedly prints images on the plurality of articles 2 using the 1st to 500th nozzles 51. That is, the nozzle 51 that ejects ink is fixed.

  As a result, there may be a case where the nozzle 51 from which ink is not ejected appears for a long time. In the unused nozzle 51, the ink evaporates for a long time. As a result, the unused nozzles 51 may be clogged.

  Therefore, when the same image is repeatedly printed on the plurality of articles 2 at the same position, and when the width of the repeated image in the Y-axis direction is smaller than the drawing width of the head 5 in the Y-axis direction, the control unit 4 determines in advance. The Y-axis fixed position is changed at the given timing. The control unit 4 changes the nozzle 51 used for repeated image printing. As a result, the control unit 4 shifts the nozzles 51 used for repeated image printing. This prevents the nozzles 51 that are not used from being generated during repeated printing of images.

  The control unit 4 changes the nozzle 51 to be used every time the image is repeatedly printed a predetermined number of times. The predetermined number of times is predetermined. For example, the predetermined number of times is a number between several times to several tens of times. The predetermined number of times may be one. The change cycle (timing) of the nozzle 51 to be used may be determined based on an element other than the number of times of printing. For example, the change timing may be determined based on time. The Y-axis fixed position may be changed every few minutes, every tens of minutes, or every few tens of minutes.

  FIG. 23 shows an example of changing the nozzle used. FIG. 23 shows an example of moving the head 5 in the X-axis direction while fixing the head 5 in the Y-axis direction during ink ejection. FIG. 23 shows an example of drawing an image of a character string of two alphabetic lines.

  The drawing width of the head 5 is determined by the length from the upper end nozzle 51 to the lower end nozzle 51 in the Y-axis direction. Then, the width Y1 of the repeated image shown in FIG. 23 in the Y-axis direction is longer than ½ of the width (drawing width) of the head 5 in the Y-axis direction. In such a case, first, the control unit 4 sets the Y-axis fixed position to a position where the upper end in the Y-axis direction of the repeated image printing range and the uppermost nozzle 51 in the Y-axis direction overlap (upper end matching position). . When changing the nozzle 51 to be used, the control unit 4 changes the Y axis fixed position to a position where the lower end in the Y axis direction of the repeated image print range overlaps with the lowest nozzle 51 in the Y axis direction (lower end coincidence). position). FIG. 23 shows an example in which the Y-axis fixed position is changed from the upper end coincidence position to the lower end coincidence position.

  When the image is repeatedly printed a predetermined number of times after the change to the lower end coincidence position, the control unit 4 sets the Y axis fixed position to the upper end coincidence position. That is, the control unit 4 switches the Y axis fixed position alternately. The control unit 4 sets the Y axis fixed position to either the upper end coincidence position or the lower end coincidence position. Thereby, the nozzle 51 which is not used can be eliminated.

  Note that the width Y1 of the repeated image in the Y-axis direction may be shorter than ½ of the drawing width of the head 5 in some cases. In such a case, even if the control unit 4 switches the Y-axis fixed position between the upper end coincidence position and the lower end coincidence position, the nozzle 51 that is not used appears. Therefore, the control unit 4 sequentially switches the nozzles 51 used for printing. The nozzle 51 that is not used is prevented from coming out.

  For example, the control unit 4 measures the unused time for each nozzle 51. In other words, the control unit 4 measures the time that does not face the print range of the image for each nozzle 51. When changing the used nozzle, the control unit 4 changes the Y-axis fixed position so that the nozzle 51 with the longest non-use time faces the image printing range. The control unit 4 changes the Y-axis fixed position so that the printing ranges face as many nozzles 51 as possible with the longest non-use time.

  The nozzle 51 of the head 5 is divided into a plurality of nozzle blocks 5B (see FIG. 4). Therefore, the control unit 4 may change the Y-axis fixed position so that the unused block, which is the nozzle block 5B that has not been used, repeatedly faces the print position of the image. In other words, the control unit 4 may switch the Y-axis fixed position for each nozzle block 5B.

  In addition, a plurality of repeated images may be printed on one article 2 based on the plurality of image data D2. In this case, the control unit 4 sets the Y-axis fixed position so that the used nozzles 51 are different for each repeated image in one printing surface 21. The control unit 4 sets the Y-axis fixed position so that the nozzle 51 that has not been used in the printing of the previous repeated image faces the printing range of the next repeated image.

  FIG. 24 shows an example in which a plurality of repeated images are printed on one article 2. An example of a change of a use nozzle is shown. FIG. 24 shows an example of moving the head 5 in the X-axis direction while fixing the head 5 in the Y-axis direction during ink ejection. In FIG. 24, the character string “ABCDEFGH” is the first repeated image. The character string “IJKLMNOPQ” is the second repeated image. In the example of FIG. 24, the interval between the character strings is wider than the length of the head 5 in the Y-axis direction.

  In such a case, the control unit 4 moves the head 5 in the X-axis direction for printing the first repetitive image. After the printing of the first repeated image is completed, the control unit 4 moves the head 5 to the moving unit 6 toward the printing start position of the second repeated image. At this time, the head 5 is moved in the X-axis direction and the Y-axis direction. Then, as shown in FIG. 24, the control unit 4 moves the head 5 so that the nozzles 51 used in the first repeated image and the second repeated image are different.

(Adjustment of the discharge time interval when the Y-axis fixed position is changed)
Next, with reference to FIG. 25, an example of adjustment of the discharge time interval accompanying the change of the Y-axis fixed position according to the embodiment will be described. FIG. 25 is a diagram illustrating an example of a flow of adjusting the discharge interval according to the change of the Y-axis fixed position according to the embodiment.

  In the nozzle 51 that is not used (does not eject ink) and has a long time, the viscosity of the ink increases. The ink should be ejected before the ink having a high viscosity has hardened. However, when the driving voltage is small (when the pressure applied to the flow path is small), ink with a high viscosity may not be ejected. Therefore, when the Y-axis fixed position is changed, when there is a nozzle 51 that has not ejected ink for a predetermined allowable time or longer, the ink ejection amount per dot is temporarily increased.

  Therefore, the control unit 4 manages the time that is not used for each nozzle 51 (time when ink is not ejected, non-use time). The storage unit 43 stores non-use time management data D6 for managing the time not used (see FIG. 10). The control unit 4 causes the storage unit 43 to update the non-use time management data D6 every time one article 2 is printed. When cleaning is performed, the control unit 4 resets the non-use time of all the nozzles 51 to zero.

  The start of FIG. 25 is the time when the Y-axis fixed position is changed. First, the control unit 4 refers to the non-use time management data D6. And the control part 4 confirms whether the nozzle 51 which was not used before the Y-axis fixed position change and the non-use time is more than the allowable time is in the nozzle 51 to be used for printing from now on. (Step # 71).

  If there is no nozzle 51 whose unused time is longer than the allowable time (No in step # 71), this flow ends (end). When there is a nozzle 51 whose non-use time is longer than the allowable time (Yes in Step # 71), the control unit 4 checks whether or not the set discharge time interval is the maximum interval (Step # 72). The maximum interval is the maximum discharge time interval among the discharge time intervals that can be set. For example, the control unit 4 checks whether or not the discharge time interval is 5 mm.

  When the ejection time interval is the maximum interval (Yes in step # 72), the ink ejection amount (droplet amount) per dot is maximized. High viscosity ink should be ejected. Therefore, when the discharge time interval is the maximum interval (Yes in step # 72), this flow ends (end). On the other hand, when the discharge time interval is not the maximum interval (No in step # 72), the control unit 4 expands the discharge time interval to the maximum interval (step # 73). For example, the control unit 4 sets the discharge interval to 5 mm.

  It is sufficient that high viscosity ink can be ejected. There is no need to continue printing at maximum intervals for a long time. Therefore, the control unit 4 prints a predetermined number of articles 2 at the maximum interval (step # 74). The predetermined number may be one to several, for example. When a predetermined number of articles 2 have been printed, the control unit 4 returns the discharge interval to the discharge interval before enlargement (step # 75). Then, this flow ends (END).

(Printing based on photographing of printing surface 21)
Next, an example of printing based on photographing of the printing surface 21 in the image forming apparatus 1 according to the embodiment will be described with reference to FIGS. FIG. 26 is a diagram illustrating an example of a portion related to photographing of the printing surface 21 in the image forming apparatus 1 according to the embodiment. FIG. 27 is a diagram illustrating an example of the flow of the automatic image addition mode according to the embodiment. FIG. 28 is a diagram illustrating an example of a flow of a copy mode according to the embodiment.

  The image forming apparatus 1 includes a reading device 47 that reads the printing surface 21 of the article 2 (see FIG. 1). The reading device 47 is a camera provided in the image forming apparatus 1. The reading device 47 images the article 2 on the transport line. For example, the reading device 47 captures a range that can be printed by the image forming apparatus 1.

  As shown in FIG. 26, the reading device 47 includes a lens 47a, an image sensor 47b, and a camera module 47c. The camera module 47c generates shooting data D7 (image data) based on the image signal output from the image sensor 47b. The reading device 47 transmits shooting data D7 obtained by shooting to the storage unit 43. The storage unit 43 stores shooting data D7.

  The image forming apparatus 1 has an automatic image addition mode and a copy mode as print modes based on photographing. It is possible to select on the operation panel 9 whether to print in the automatic image addition mode or the copy mode. The operation panel 9 accepts the selection of printing in the image automatic addition mode or printing in the copy mode.

1. Automatic image addition mode The automatic image addition mode is a mode in which an image associated with a specific image is added to the print surface 21 based on the specific image attached to the article 2. The automatic image addition mode is a mode in which an image associated with the specific mark is added to the printing surface 21 based on the specific mark attached to the article 2. It can be said that the image automatic addition mode is a mode in which a linked image is automatically printed on the printing surface 21 when a specific image and a specific mark are attached to the article 2. The specific image and the specific mark may not be printed on the article 2. The specific image and the specific mark may be, for example, a seal.

  For example, when an image indicating the language used is attached as a specific image, the image forming apparatus 1 automatically prints a character string in the corresponding language. Even if articles 2 having different destinations are mixed in the line, a character string suitable for the destination can be automatically printed. It is not necessary to specify the language used or the image data D2 of the character string to be used on the computer 200 or the operation panel 9 one by one.

  For example, when a triangular mark indicating Europe is attached as the specific mark, the image forming apparatus 1 automatically prints an image indicating that the product is for Europe. Even if articles 2 having different destinations are mixed in the line, an appropriate image can be automatically attached. The computer 200 and the image forming apparatus 1 do not need to designate an image indicating a destination one by one.

  FIG. 28 is a diagram illustrating an example of the flow of printing in the automatic image addition mode using FIG. The start of FIG. 27 is, for example, the time when printing in the image automatic addition mode is instructed on the operation panel 9. First, the control unit 4 causes the reading device 47 to start imaging (step # 81). The reading device 47 photographs the article 2 that is stopped in the printable range of the image forming apparatus 1 or passes through the printable range.

  Here, the storage unit 43 stores determination data D8. The determination data D8 is data for determining whether or not a specific image and a specific mark are attached to the article 2 (see FIG. 26). The determination data D8 is prepared for each specific image and specific mark. The control unit 4 confirms whether or not a specific image and a specific mark are attached to the article 2 based on the determination data D8.

  The determination data D8 includes determination image data D9 as image data indicating a specific image or a specific mark. For example, when the specific image is a number indicating a model number, the determination image data D9 is image data indicating a model number and including a number.

  The determination data D8 includes automatic printing image data D10 as image data D2 of an image to be printed corresponding to the specific image and the specific mark. The determination data D8 includes automatic print information D11. The automatic print information D11 includes information such as the print start position, print resolution, and ejection time interval for the automatic print image data D10. In the automatic print information D11, the distance in the X-axis direction and the Y-axis direction from the feature point in the specific image and the specific mark can be set as the print start position. The feature points can be, for example, the specific image, the upper right corner, the lower right corner, the upper left corner, and the lower left corner of the specific mark. The automatic print information D11 can be set by the computer 200 or the operation panel 9.

  The control unit 4 determines whether or not the specific image and the specific mark are included in the shooting data D7 (step # 82). For example, the control unit 4 performs pattern matching between the determination image data D9 and the shooting data D7. And the control part 4 determines whether the specific image and the specific mark are contained in the imaging | photography data D7.

  When it is determined that the specific image and the specific mark are not included in the shooting data D7 (No in Step # 82), the flow returns to Step # 81. When it is determined that the specific image and the specific mark are included in the shooting data D7 (Yes in Step # 82), the control unit 4 causes the moving unit 6 to align the head 5 (Step # 83). The control unit 4 adjusts the position of the head 5 in the X-axis direction and the Y-axis direction to a position separated from the specific image and the specific mark by a distance defined by the automatic print information D11.

  Note that the specific image or the specific mark and the head 5 are located within the photographing range of the reading device 47. The specific image or the specific mark and the head 5 are reflected in the photographing data D7. Therefore, the control unit 4 may recognize that the position of the head 5 in the X-axis direction has become the print start position based on the distance between the specific image or specific mark on the captured data D7 and the head 5. The control unit 4 adjusts the position of the head 5 in the Y-axis direction so that the upper end and the lower end of the image are within the range of the drawing width in the Y-axis direction. The control unit 4 adjusts the position of the head 5 in the Z-axis direction based on the ejection time interval defined by the automatic print information D11.

  When the head 5 has been aligned, the control unit 4 causes the head 5 to print an image corresponding to the specific image or an image corresponding to the specific mark (step # 84). The control unit 4 performs printing based on the automatic printing image data D10 corresponding to the specific image. Alternatively, the control unit 4 causes printing based on the image data for automatic printing D10 corresponding to the specific mark. Thereby, an image associated with the specific image or an image associated with the specific mark can be automatically printed. After printing, the flow returns to step # 81.

2. Copy Mode The copy mode is a mode in which the sample article 2 is imaged and an image similar to the sample is automatically printed on the printing surface 21. By using the copy mode, the same print as the sample can be applied to the plain article 2 without editing the image data D2 by the computer 200.

  FIG. 29 is a diagram illustrating an example of a flow of printing in a copy mode using FIG. The start in FIG. 28 is, for example, the time when printing in the copy mode is instructed on the operation panel 9. First, the control unit 4 causes the reading device 47 to take a sample (step # 91). The user places a sample in the imaging range of the reading device 47. The user sets the sample so that the entire image is captured. After setting, the user operates the imaging button on the operation panel 9. In other words, the user releases the shutter for photographing the sample.

  The reading device 47 generates sample photographing data D7 (step # 92). The storage unit 43 stores sample photographing data D7 (step # 93). The control unit 4 generates image data D2 used for printing based on the photographing data D7 of the sample article 2 (step # 94). Further, the control unit 4 generates print setting information D3 for each generated image data D2 (step # 95).

  For example, the control unit 4 extracts a two-dimensional code, a one-dimensional code, and a symbol string from the sample photographing data D7. And the control part 4 produces | generates each image data D2 of the extracted element. The control unit 4 determines a print range of the generated image data D2 based on the sample image data D2. Further, the control unit 4 sets an ejection time interval according to the type of the image data D2.

  Then, the sample article 2 is removed. The conveying device 3 starts conveying the article 2 to be printed with the same image as the sample (step # 96). The control unit 4 performs printing on the article 2 based on the generated image data D2 and print setting information D3 (step # 97). Thereafter, the control unit 4 causes the head 5 and the moving unit 6 to perform printing similar to the sample on the conveyed article 2 (end). For example, until the end of printing is input on the operation panel 9, the control unit 4 causes the article 2 to be conveyed to perform printing similar to the sample.

(Modification)
Next, modified examples of the image forming apparatus 1 according to the embodiment will be described with reference to FIGS. 29 to 31. 29 and 30 are diagrams illustrating an example of the image forming apparatus 1 according to the modification. FIG. 31 is a diagram illustrating an example of a flow of movement of the head 5 according to the modification in the Z-axis direction.

  As the image forming apparatus 1 according to the embodiment, the example in which the discharge time interval is set according to the image type of the image data D2 and the setting on the operation panel 9 has been described. And the example which adjusted the space | interval of the nozzle 51 and the printing surface 21 using the space | interval sensor 46 according to the set discharge time interval was demonstrated. However, there is a case where it is not necessary to change the ejection time interval according to the type of image. Moreover, the article 2 to be printed may not change. In such a case, it is not necessary to use the distance sensor 46.

  In the modification, the interval sensor 46 is not provided. In the modification, the distance between the nozzle 51 and the printing surface 21 is stabilized by using the interval regulating member 49. The tip of the interval regulating member 49 on the article side is in contact with the article 2 during ink ejection. The interval regulating member 49 prevents the interval between the nozzle 51 and the printing surface 21 from being equal to or less than the reference interval. The reference interval is determined as appropriate. The reference interval is, for example, any length within a range of 1 mm to 5 mm.

  The spacing regulating member 49 projects from the nozzle 51 in the Z-axis direction and the direction in which the article 2 is located. The interval regulating member 49 protrudes by the length of the reference interval. Even if the article 2 swings so as to approach the nozzle 51, the interval regulating member 49 prevents the nozzle 51 and the article 2 from contacting each other. As shown in FIG. 29, the interval regulating member 49 is attached to the upper portion of the head 5, for example. The space regulating member 49 may be attached to the lower part and the side surface of the head 5. The spacing regulating member 49 is in contact with the article 2. And the article | item 2 is conveyed. The spacing regulating member 49 can be a roller or a ball so as not to damage the surface of the article 2 and to prevent (friction) the article conveyance. The interval regulating member 49 rotates in accordance with the movement of the article 2 or the head 5 in the X-axis direction.

  As shown in FIG. 30, the interval regulating member 49 includes a contact sensor 410 for detecting that the interval regulating member 49 is in contact with the article 2. For example, the contact sensor 410 is a pressure-sensitive sensor. The contact sensor 410 outputs a voltage at a contact level when the distance regulating member 49 and the article 2 are in contact with each other. On the other hand, when the distance regulating member 49 and the article 2 are not in contact with each other, a non-contact level voltage is output. Based on the output of the contact sensor 410, the control unit 4 recognizes whether or not the interval restriction member 49 is in contact with the article 2.

  Next, an example of movement control in the Z-axis direction of the head 5 in the image forming apparatus 1 according to the modification will be described with reference to FIG. The start in FIG. 31 is a point in time when printing is started. In other words, it is the time when the conveyance of the article 2 to be printed on the conveyance line (conveyance device 3) is started. When printing on a plurality of articles 2 continuously, it is the time when printing on the first article 2 is started. When printing the same image continuously on the same article 2 in lot units (minimum production unit), it is the time when printing on the first article 2 is started.

  First, the control unit 4 sets the position of the head 5 in the Z-axis direction as a collision avoidance position (step # 101). Subsequently, the control unit 4 recognizes the image data D2 used for printing (step # 102). Sometimes the article 2 is printed using a plurality of image data D2. When printing a plurality of images, a plurality of image data D2 are used for printing. Then, the control unit 4 sets an ejection time interval for each image data D2.

  Then, the control unit 4 performs a pressing process before starting printing of one image (image data D2) (step # 103). During the pressing process, the control unit 4 moves the head 5 to the moving unit 6 in the Z-axis direction until the output of the contact sensor 410 changes from the non-contact level to the contact level. In other words, the control unit 4 moves the head 5 to the moving unit 6 toward the article 2 in the Z-axis direction until the interval between the nozzle 51 and the printing surface 21 becomes the reference interval.

  Eventually, printing of one image by the head 5 is started (step # 104). The interval regulating member 49 prevents the interval from becoming less than the reference interval during image printing. Eventually, printing of one image is completed (step # 105).

  Then, the control unit 4 checks whether or not all images have been printed on the printing surface 21 (step # 106). In other words, the control unit 4 confirms whether printing of one article 2 is completed. When all images have not been printed on the printing surface 21 (No in Step # 106), the control unit 4 moves the head 5 to the next printing position (Step # 107). The control unit 4 moves the head 5 in the X axis direction and the Y axis direction toward the print start position of the next image.

  When all the images have been printed on the printing surface 21 (Yes in Step # 106), it is confirmed whether or not the next article 2 is to be printed (Step # 108). In other words, the control unit 4 confirms whether or not printing of the article 2 for one lot has been completed (step # 108). When printing the next article 2 (Yes in step # 108), the flow returns to step # 101. The control unit 4 returns the position of the head 5 in the Z-axis direction to the collision avoidance position. As described above, after the printing on one article 2 is completed, the control unit 4 moves the head 5 to the moving unit 6 in the Z-axis direction and the direction in which the interval is widened. Then, the control unit 4 sets the position of the head 5 in the Z-axis direction as a collision avoidance position. And the control part 4 performs a pressing process again. That is, the control unit 4 moves the head 5 to the moving unit 6 in the Z-axis direction and the direction in which the interval is narrowed before the start of printing on the next article 2. The moving unit 6 moves the head 5 until the output of the contact sensor 410 changes from the non-contact level to the contact level.

  Thus, the image forming apparatus 1 includes the head 5, the moving unit 6, and the control unit 4. The head 5 includes nozzles 51 arranged in a row. The head 5 prints an image by ejecting ink from the nozzle 51 onto the printing surface 21 of the article 2 based on the image data D2. The moving unit 6 moves the head 5 in at least two axial directions. The control unit 4 controls the moving unit 6. Each axial direction is orthogonal. One of the two axial directions is a Z-axis direction that is a depth direction when the printing surface 21 is the front surface.

  Thereby, the position of the head 5 can be moved by the moving unit 6 and the control unit 4. The position of the head 5 can be moved in at least two axial directions. That is, the position of the head 5 can be changed at least in a plane. Therefore, the position of the head 5 can be easily adjusted. The head 5 can be moved to a position where maintenance work such as cleaning or replacement can be easily performed. Therefore, it becomes easy to perform maintenance work. The work burden on the user can be reduced.

  The nozzles 51 are arranged along the Y-axis direction, which is the height direction when the printing surface 21 is the front surface. The moving unit 6 includes a first moving mechanism 61, a second moving mechanism 62, and a third moving mechanism 63. The control unit 4 moves the head 5 to the first moving mechanism 61 in the Z-axis direction. The control unit 4 moves the head 5 to the second moving mechanism 62 in the Y-axis direction. The control unit 4 moves the head 5 to the third moving mechanism 63 in the X-axis direction that is the width direction when the printing surface 21 is the front surface.

  Thereby, the head 5 can be moved in three dimensions with respect to the article 2. The head 5 can be moved in three directions of the height, width, and depth of the article 2. The head 5 can be moved to a desired position. The head 5 can be freely moved to a position where maintenance work can be easily performed. The work burden on the user can be reduced. In addition, an image can be printed while the article 2 is stopped. Further, when the printing head is fixed, it is necessary to arrange a plurality of printing heads side by side in order to print in a range wider than the nozzle 51 row of the printing head. Since the head 5 can be moved in the Y-axis direction, it is not necessary to provide a plurality of heads 5.

  A plurality of images may be printed on one article 2 in some cases. The position of each image may be separated in the Y-axis direction. When the conventional head 5 is fixed, it is necessary to provide a plurality of heads 5 for such printing. However, in the image forming apparatus 1, the head 5 can be moved in the Y-axis direction (height direction). That is, when the printing surface 21 is printed based on the plurality of image data D2, the control unit 4 varies the position of the head 5 in the Y-axis direction for each image. Thereby, a plurality of images separated in the Y-axis direction can be printed with one head 5. Each image can be printed without providing a plurality of heads 5.

  Further, when printing on the stopped article 2, the control unit 4 moves the head 5 to the moving unit 6 in the X-axis direction during ink ejection. Thereby, it is possible to print a two-dimensional image on the printing surface 21 while moving the head 5 to the moving unit 6 in the X-axis direction.

  When printing on the article 2 moving along the X-axis direction, the control unit 4 fixes the position of the head 5 in the X-axis direction to the moving unit 6 during ink ejection. Thereby, a two-dimensional image can be printed on the printing surface 21 along the X-axis direction.

  When printing on the article 2 moving along the X-axis direction, the control unit 4 moves the head 5 to the moving unit 6 in the X-axis direction so that the relative speed between the article 2 and the head 5 is constant. Move. Thereby, the relative speed of the article 2 and the head 5 can be made constant. The distance that the article 2 travels with respect to the nozzle 51 can be made constant during the ink ejection cycle. Regardless of the moving speed of the article 2, an image with a certain resolution can be printed on the printing surface 21.

  The image forming apparatus 1 also includes a speed sensor 44 for detecting the moving speed of the article 2 in the X-axis direction. The control unit 4 recognizes the moving speed based on the output of the speed sensor 44. The control unit 4 determines the moving distance of the article 2 during the ink discharge reference period based on the recognized moving speed. The control unit 4 determines a 1-dot width that is a width in the X-axis direction of 1 dot based on the resolution. The control unit 4 moves the head 5 to the moving unit 6 along the X-axis direction so that the relative speed between the article 2 and the head 5 is a speed obtained by dividing the one-dot width by the reference period. The control unit 4 causes the head 5 to eject ink at a reference period. Thereby, the distance which the articles | goods 2 advance with respect to the nozzle 51 can be made constant during a reference | standard period. Since the moving speed is measured by the speed sensor 44, the moving speed of the article 2 can be kept constant even if there is a fluctuation. Even if the moving speed of the article 2 is high, an image with a constant resolution can be printed on the printing surface 21.

  Further, the control unit 4 causes the head 5 to eject ink so that the ink ejection amount per unit time from the nozzle 51 to be used increases as the relative speed between the article 2 and the head 5 increases. The control unit 4 causes the head 5 to eject ink so that the ink ejection amount per unit time from the nozzle 51 to be used decreases as the relative speed decreases. Thereby, an image having the same density can be printed regardless of the conveyance speed of the article 2.

  Conventionally, a drying prevention cap has been attached to the head 5 provided in the line by the operator's hand. Therefore, the image forming apparatus 1 includes a cap portion 7 that covers an exposed surface of the head 5 where the nozzle 51 is exposed and prevents the ink from drying. When a predetermined retreat condition is satisfied, the control unit 4 moves the head 5 to the moving unit 6 toward the retreat position. The retracted position is a position where the head 5 is fitted into the cap portion 7 and the exposed surface is covered with the cap portion 7. Thereby, mounting | wearing to the head 5 of the cap for drying prevention can be automated. Eliminates the need to wear the anti-drying cap manually. In addition, when the printing head is fixed, it is necessary to add a mechanism for moving the cap when automating the installation of the anti-drying cap. That is, a large modification of the mechanism for conveying the article 2 was necessary. According to the image forming apparatus 1, such modification is unnecessary. The image forming apparatus 1 that can be easily maintained can be provided.

  In addition, the image forming apparatus 1 includes an operation panel 9 that receives an operation. The evacuation condition is one or more of the following: the operation panel 9 accepts an instruction to evacuate the head 5, the predetermined evacuation time is reached, and the printing is completed. . Thereby, the cap part 7 can be automatically attached to the head 5 based on a predetermined trigger. A trigger for automatically attaching the cap portion 7 to the head 5 can be set. Moreover, the cap part 7 can also be automatically attached to the head 5 according to the time of a line stop like a lunch break. In addition, the cap unit 7 can be automatically attached to the head 5 when printing is completed.

  Conventionally, the cleaning of the head 5 (nozzle 51) provided in the line has been performed by the operator's hand. For example, the worker has performed an operation of removing high-viscosity ink and dust accumulated in the nozzle 51 with a blade. Therefore, the image forming apparatus 1 includes a cleaning member 81 for cleaning the nozzle 51. When a predetermined cleaning condition is satisfied, the control unit 4 moves the head 5 to the moving unit 6 so that the nozzle 51 is rubbed by the cleaning member 81. Thereby, the cleaning of the head 5 can be automated. Eliminate manual cleaning. When the printing head is fixed, it is necessary to add a mechanism for moving the cleaning member when the cleaning of the head 5 is automated. That is, a large modification of the mechanism for conveying the article 2 was necessary. For automation, no major modification of the machine that transports the article 2 is necessary. Therefore, the image forming apparatus 1 that can be easily maintained can be provided.

  In addition, the image forming apparatus 1 includes an operation panel 9 that receives an operation. The cleaning conditions are that the operation panel 9 has received a cleaning instruction for the nozzle 51, that a predetermined cleaning time has been reached, that a predetermined number of articles 2 have been printed after the start of printing or immediately before cleaning, and printing Is one or a plurality of completions. Thereby, cleaning can be automatically started based on a predetermined trigger. An automatic cleaning start trigger can be set. Further, the head 5 can be automatically cleaned at the time of line stop such as lunch break. Further, the head 5 can be automatically cleaned every time a predetermined number of articles 2 are printed. Further, the head 5 can be automatically cleaned when printing is completed.

  In addition, the image forming apparatus 1 includes a cleaning unit 82 that causes the cleaning liquid to flow through the cleaning member 81 before rubbing the nozzles 51 and that cleans the cleaning member 81 after cleaning with the cleaning liquid. Thereby, since the cleaning liquid is applied to the cleaning member 81 before rubbing the nozzle 51, the nozzle 51 can be prevented from being damaged. Further, the cleaning member 81 at the start of cleaning can always be kept clean. Dirt adhered during the previous cleaning is not rubbed against the nozzle 51 (head 5) during the current cleaning.

  The image forming apparatus 1 includes a head 5, a moving unit 6, and a control unit 4. The head 5 includes nozzles 51 arranged in a row. The head 5 prints an image by ejecting ink from the nozzle 51 onto the printing surface 21 of the article 2 based on the image data D2. The moving unit 6 moves the head 5 in the Z-axis direction, which is the depth direction when the printing surface 21 is the front surface. The moving unit 6 moves the head 5 in at least two axial directions. The control unit 4 sets an ejection time interval that is an interval between the nozzle 51 during ink ejection and the printing surface 21 in accordance with the image to be printed or the article 2. The control unit 4 moves the head 5 to the moving unit 6 in the Z-axis direction so that the set discharge time interval is reached. Thereby, the head 5 can be automatically moved in the Z-axis direction according to the image to be printed and the article 2. Depending on the image or article 2 to be printed, the distance between the head 5 (nozzle 51) and the article 2 (printing surface 21) can be automatically adjusted. The interval between the nozzle 51 and the printing surface 21 can be set to an appropriate interval.

  Further, the control unit 4 may set the ejection time interval based on the print setting information D3 associated with the image data D2 used for image printing. Accordingly, the interval between the nozzle 51 and the printing surface 21 can be automatically set to an appropriate interval simply by giving the image data D2 and the print setting information D3 to the image forming apparatus 1.

  Further, the image forming apparatus 1 includes a storage unit 43 that stores definition data D4 that defines an ejection time interval for each type of image. When the print setting information D3 includes information indicating the image type, the control unit 4 may set the ejection time interval based on the image type and the definition data D4 included in the print setting information D3. Accordingly, the type of image to be printed can be recognized based on the definition data D4. The interval between the nozzle 51 and the printing surface 21 can be automatically set to an appropriate interval according to the type of image to be printed. When the image type requires high precision and high image quality, the distance between the nozzle 51 and the printing surface 21 can be automatically set closer. When the image type does not require high precision and high image quality, the distance between the nozzle 51 and the printing surface 21 can be automatically set to be longer.

  Further, when the print setting information D3 includes information indicating the value of the discharge time interval, the control unit 4 may set the discharge time interval based on the value included in the print setting information D3. Thereby, the space | interval of the nozzle 51 and the printing surface 21 can be match | combined with the value directly defined by the print setting information D3. The interval between the nozzle 51 and the printing surface 21 can be adjusted based on a predefined value.

  Further, the control unit 4 may analyze the image data D2 and determine the type of the image data D2. The control unit 4 may set an ejection time interval based on the determined image type and definition data D4. Thereby, it is possible to analyze the image data D2 and recognize the type of image to be printed. The interval between the nozzle 51 and the printing surface 21 can be automatically set to an appropriate interval according to the type of image to be printed. When the image type requires high precision and high image quality, the distance between the nozzle 51 and the printing surface 21 can be automatically set closer. When the image type does not require high precision and high image quality, the distance between the nozzle 51 and the printing surface 21 can be automatically set to be longer.

  The image forming apparatus 1 may include an operation panel 9 that receives selection of the type of image to be printed. The control unit 4 may set the ejection time interval based on the image type selected on the operation panel 9 and the definition data D4. Thereby, the user can set the precision of the image to be printed on the operation panel 9. When it is desired to prevent the ink landing position from shifting as much as possible, a print mode having a high required level may be selected. Based on the user's selection, the interval can be set narrow so that the ink landing position is less displaced. If there is no problem even if the ink landing position is shifted, a printing mode having a low required level may be selected. Based on the user's choice, the interval can be set wider. Therefore, the user can set the interval between the nozzle 51 and the printing surface 21 to a desired interval.

  As the types of images that can be selected, there are a symbol string, a one-dimensional code, and a two-dimensional code. When the symbol string is selected, the control unit 4 sets the discharge time interval to the first interval. When the one-dimensional code is selected, the control unit 4 sets the discharge interval to a second interval that is narrower than the first interval. When the two-dimensional code is selected, the control unit 4 sets the discharge interval to a third interval that is narrower than the second interval. Thereby, the user can select an ejection time interval according to the image to be printed. The interval between the nozzle 51 and the printing surface 21 can be set so that a desired printing result can be obtained simply by selecting the type of image.

  The surface of the article 2 may be smooth (fine). When the surface is smooth, the narrower the distance between the nozzle 51 and the printing surface 21, the higher the quality of the printed image. This is because the ink landing position does not shift and the ink is evenly deposited on the surface of the article 2. On the other hand, when the surface is rough, it may be preferable to keep a certain distance between the nozzle 51 and the printing surface 21. When the interval between the nozzle 51 and the printing surface 21 is increased, the landing positions of the ink are likely to vary. This is because the ink may be applied so as to adapt to the unevenness of the surface due to this variation. Therefore, the image forming apparatus 1 may include an operation panel 9 that receives the setting of the smoothness level of the surface of the article 2. The controller 4 narrows the discharge time interval as the set smoothing level is higher. The controller 4 narrows the discharge time interval as the set smoothing level is lower. Thereby, according to the article | item 2, the space | interval of the nozzle 51 and the printing surface 21 can be set. When the surface is smooth, the interval can be narrowed. On the other hand, when the surface is rough, the interval can be increased. The interval can be adjusted so that the image quality is improved according to the state of the printing surface 21 of the article 2.

  The wider the distance between the nozzle 51 and the printing surface 21, the more the ink landing position deviates from the target position. For this reason, even when the same amount of ink is ejected, the density of the printed image tends to become lighter as the interval increases. Therefore, the control unit 4 causes the head 5 to eject ink such that the smaller the ejection time interval, the smaller the ink ejection amount per dot. The controller 4 causes the head 5 to eject ink so that the greater the ejection time interval, the greater the amount of ink ejected per dot. Accordingly, the amount of ink ejected from the nozzle 51 can be adjusted in accordance with the interval between the nozzle 51 and the printing surface 21. An image that is neither too dark nor too light can be printed on the printing surface 21.

  The present invention has an aspect as the data structure of the printing data D1. Specifically, the printing data D1 is input to the image forming apparatus 1. The data structure of the print data D1 includes image data D2 corresponding to the image to be printed and print setting information D3 associated with the image data D2. The print setting information D3 determines the distance between the head 5 that prints an image by ejecting ink and the article 2, and moves the head 5 in the Z-axis direction, which is the depth direction when the printing surface 21 of the article 2 is the front. Contains information for Thereby, the data D1 for printing can be made into a data structure including information for determining the distance between the head 5 and the article 2. By simply giving the image data D2 and the print setting information D3 to the image forming apparatus 1, the distance between the head 5 and the article 2 can be automatically adjusted to an appropriate distance.

  The image forming apparatus 1 includes a head 5, a moving unit 6, and a control unit 4. The head 5 includes nozzles 51 arranged in a line along the Y-axis direction that is the vertical direction when the printing surface 21 of the article 2 is the front surface. The head 5 prints an image by ejecting ink from the nozzle 51 onto the printing surface 21 of the article 2 based on the image data D2. The moving unit 6 moves the head 5 in the Y-axis direction and the Z-axis direction that is the depth direction when the printing surface 21 is the front surface. When repeatedly printing images on a plurality of articles 2 at the same position, the control unit 4 sets the Y-axis fixed position. During the ink ejection for repeatedly printing images, the control unit 4 fixes the position of the head 5 in the Y-axis direction to the moving unit 6 at the Y-axis fixed position. When the width of the repeated image in the Y-axis direction is narrower than the drawing width of the head 5 in the Y-axis direction, the control unit 4 changes the Y-axis fixed position at a predetermined timing. The controller 4 changes the nozzle 51 used for repeated image printing.

  In the line, the same image may be repeatedly printed at the same position on the article 2 (printing surface 21). The control unit 4 causes the nozzle 51 facing the printing position to eject ink. The fixed position of the head 5 in the Y-axis direction can be changed between the repeated images. That is, the nozzle 51 used for printing can be changed. The unused nozzles 51 can be eliminated or reduced. Therefore, occurrence of clogging at the nozzle 51 can be prevented.

  Further, the control unit 4 changes the Y-axis fixed position every time the image is repeatedly printed a predetermined number of times. Thereby, the Y-axis fixed position can be changed every time the image is repeatedly printed a predetermined number of times. Therefore, the range of the nozzles 51 used for printing can be switched every time the image is printed a predetermined number of times. Therefore, occurrence of clogging at the nozzle 51 can be prevented.

  Further, the nozzle 51 of the head 5 is divided into a plurality of nozzle blocks 5B. When changing the Y-axis fixed position, the control unit 4 moves the head 5 to the moving unit 6 so that the unused block, which is the nozzle block 5B that has not been used, repeatedly faces the image printing position. Thus, the head 5 can be moved in the Y-axis direction so that unused blocks are eliminated during repeated image printing.

  Further, when changing the Y-axis fixed position, the control unit 4 changes the Y-axis fixed position so that the nozzle 51 that has not been used before the change of the Y-axis fixed position repeatedly faces the image printing position. Further, the control unit 4 maximizes the ink discharge amount per dot. As a result, the amount of ink discharged from the nozzle 51 that has not been used can be temporarily increased. From the nozzle 51 that has not been used, the ink whose viscosity has been increased by drying can be actively discharged.

  As the distance between the head 5 (nozzle 51) and the article 2 (printing surface 21) is increased, the ink landing position is more likely to deviate from the target position. When the ink discharge amount per dot is maximized by changing the Y-axis fixed position, the control unit 4 increases the discharge time interval between the nozzle 51 and the print surface 21 during ink discharge. When the predetermined number of articles 2 are printed, the control unit 4 returns the discharge time interval to the discharge time interval before enlargement. When the ink discharge amount is increased, the interval between the nozzle 51 and the printing surface 21 can be increased. The landing position of the ink can be appropriately dispersed. Therefore, it is possible to prevent the density of the printed image from becoming too high.

  When the width of the repeated image in the Y-axis direction is narrower than the drawing width of the head 5 in the Y-axis direction, the unused nozzle 51 appears. Among the nozzles 51, there are nozzles 51 that are not used in one or both of the upper end portion and the lower end portion in the Y-axis direction. The control unit 4 sets the Y-axis fixed position so that the upper end of the repeated image printing position in the Y-axis direction overlaps the nozzle 51 at the upper end of the head 5 in the Y-axis direction, or the Y-axis of the repeated image printing position. The Y axis fixing position is set so that the lower end in the direction and the nozzle 51 at the lower end in the Y axis direction of the head 5 overlap. Thereby, the head 5 can be moved so that the nozzle 51 which is not used by the upper end part of a Y-axis direction and a lower end part among the nozzles 51 is used.

  When printing a plurality of repetitive images on one article 2 based on a plurality of image data D2, the control unit 4 determines that the nozzles 51 used for each repetitive image in one printing surface 21 are different. Set the axis fixed position. The control unit 4 sets the Y-axis fixed position so that the nozzle 51 that has not been used in the printing of the previous repeated image faces the printing range of the next repeated image. As a result, when a plurality of repeated images are printed on one article 2, it is possible to prevent the unused nozzles 51 from being generated. The nozzle 51 used during printing of one article 2 can be switched. It is possible to prevent the clogged nozzle 51 from being generated.

  Further, the image forming apparatus 1 includes a reading device 47 that reads the printing surface 21 and generates photographing data D7. The control unit 4 determines whether or not the specific image is included in the shooting data D7. When determining that the specific image is included, the control unit 4 causes the head 5 to print an image corresponding to the specific image. Thus, an image corresponding to the specific image can be automatically printed on the article 2 simply by attaching a specific image to the article 2 in advance. Setting work on the image forming apparatus 1 and the computer 200 related to printing of the article 2 can be reduced.

  Further, the control unit 4 determines whether or not the specific mark is included in the shooting data D7. When it is determined that the specific mark is included, the control unit 4 causes the head 5 to print an image corresponding to the specific mark. Thus, an image corresponding to the specific image can be automatically printed on the article 2 simply by attaching a specific mark to the article 2 in advance. The mark may be handwritten if it can be recognized. The mark may be a seal. Setting work on the image forming apparatus 1 and the computer 200 related to printing of the article 2 can be reduced.

  Further, the control unit 4 generates image data D2 used for printing based on the shooting data D7 obtained by shooting the sample article 2. The control unit 4 causes the head 5 to perform printing on the article 2 based on the image data D2 generated based on the shooting data D7. As a result, the sample can be copied and printed on the article 2. The symbols and codes attached to the sample can be copied and printed. Setting work on the image forming apparatus 1 and the computer 200 related to printing of the article 2 can be reduced.

  The image forming apparatus 1 includes a head 5, a moving unit 6, and a control unit 4. The head 5 includes nozzles 51 arranged in a row. The head 5 prints an image by ejecting ink from the nozzle 51 onto the printing surface 21 of the article 2 based on the image data D2. The moving unit 6 moves the head 5 in the Z-axis direction, which is the depth direction when the printing surface 21 is the front surface. The moving unit 6 moves the head 5 in at least two axial directions. The control unit 4 sets an ejection time interval that is an interval between the nozzle 51 during ink ejection and the printing surface 21. The control unit 4 moves the head 5 to the moving unit 6 in the Z-axis direction, and maintains the interval between the nozzle 51 during ink ejection and the printing surface 21 at a set ejection time interval.

  Thereby, the head 5 can be moved in the Z-axis direction. By moving the head 5, the distance between the head 5 (nozzle 51) and the article 2 (printing surface 21) can be made constant. Therefore, it is possible to eliminate variations in the quality of the printed image. For example, it is possible to prevent printing of an image with uneven color or a blurred image.

  Further, the image forming apparatus 1 includes an interval sensor 46 for measuring the distance between the nozzle 51 and the printing surface 21. The control unit 4 recognizes the distance between the nozzle 51 and the printing surface 21 based on the output of the interval sensor 46. The control unit 4 performs an alignment process before starting to print an image. In the alignment process, the control unit 4 moves the head 5 to the moving unit 6 in the Z-axis direction, and sets a discharge time interval with a set interval. During the printing of the image, the control unit 4 moves the head 5 to the moving unit 6 in the Z-axis direction so that the interval is maintained at the ejection interval. Thereby, using the sensor, the interval (distance) between the nozzle 51 and the printing surface 21 can be kept constant during printing. Variations in the quality of printed images can be eliminated.

  In addition, after the printing on one article 2 is completed, the control unit 4 moves the head 5 to the moving unit 6 in the Z-axis direction and the direction in which the interval is widened, and sets the head 5 as a collision avoidance position. Prior to the start of printing on the next article 2, the control unit 4 moves the head 5 to the moving unit 6 in the Z-axis direction and the direction in which the interval is narrowed. Thereby, after the printing on the article 2 is completed, the head 5 can be retracted to a safe position. After the transported article 2 reaches the image forming apparatus 1, the head 5 can be brought close to the article 2. It is possible to eliminate the collision between the head 5 and the article 2.

  Further, the control unit 4 recognizes the distance between the nozzle 51 and the printing surface 21 before the alignment process. When the recognized interval falls within a predetermined allowable range, the control unit 4 omits the alignment process and causes the head 5 to start printing. Thereby, the case where a position alignment process is abbreviate | omitted can be provided. The start of printing on the article 2 can be accelerated. Printing speed, printing efficiency, and productivity can be improved.

  In addition, the image forming apparatus 1 according to the modified example includes an interval regulating member 49 for preventing the interval between the nozzle 51 and the printing surface 21 from being equal to or less than the reference interval. The spacing regulating member 49 projects from the nozzle 51 in the Z-axis direction and the direction in which the article 2 is located. The interval regulating member 49 can prevent the interval between the nozzle 51 and the printing surface 21 from being equal to or less than the reference interval. It is possible to prevent the head 5 (nozzle 51) from being damaged due to the collision between the head 5 and the article 2.

  The interval regulating member 49 is attached to the head 5. Thereby, the space regulating member 49 can be moved together with the head 5. Regardless of the position of the head 5, it is possible to prevent the interval between the nozzle 51 and the printing surface 21 from being equal to or less than the reference interval.

  The interval regulating member 49 is a roller or a ball. Thereby, with the movement of the head 5, the interval regulating member 49 can be smoothly moved while being in contact with the article 2. The interval regulating member 49 can be moved along the shape of the article 2 so as not to break the article 2.

  The interval regulating member 49 includes a contact sensor 410 for detecting that the interval regulating member 49 is in contact with the article 2. The contact sensor 410 outputs the first level when the interval regulating member 49 and the article 2 are in contact with each other. The contact sensor 410 outputs the second level when the interval regulating member 49 and the article 2 are not in contact with each other. The control unit 4 performs a pressing process before starting the printing of the image. During the pressing process, the control unit 4 moves the head 5 to the moving unit 6 in the Z-axis direction until the output of the contact sensor 410 changes from the second level to the first level. Thereby, it can prevent that the pressure which the space | interval control member 49 and the goods 2 contact becomes too strong. The distance regulating member 49 is not pressed too much against the article 2. Since it does not press too much, it can prevent that the space | interval of the nozzle 51 and the printing surface 21 becomes below a reference | standard space | interval. Since the distance regulating member 49 does not come into strong contact with the article 2, the article 2 is not damaged.

  After the printing on one article 2 is completed, the control unit 4 moves the head 5 to the moving unit 6 in the Z-axis direction and the direction in which the interval is widened, and sets the head 5 as a collision avoidance position. Prior to the start of printing on the next article 2, the control unit 4 moves the head 5 to the moving unit 6 in the Z-axis direction and in a direction in which the interval is narrowed until the output of the contact sensor 410 changes from the second level to the first level. Let Thereby, after the printing on the article 2 is completed, the head 5 and the spacing regulating member 49 can be retracted to a position where they cannot contact the article 2. The head 5 and the space regulating member 49 can be retracted to a safe position. After the transported article 2 reaches the image forming apparatus 1, the interval regulating member 49 can be applied to the article 2. It is possible to eliminate the collision between the head 5 and the article 2.

  The image forming system 100 includes the above-described image forming apparatus 1 and a transport apparatus 3 that transports the article 2 in the X-axis direction, which is the width direction when the printing surface 21 is the front surface. Thereby, it can print on the articles | goods 2 conveyed by a line.

  Further, in the image forming system 100, the conveying device 3 may stop the article 2 before the head 5 starts printing. The head 5 prints on the stopped article 2. When printing by the head 5 is completed, the transport device 3 resumes transport of the article 2. Thereby, it is possible to perform printing on the article 2 stopped during conveyance. Since the article 2 is stopped, the deviation of the ink landing position tends to be reduced.

  In the image forming system 100, the transport device 3 may transport the article 2 at a constant speed. The head 5 may print on the article 2 being conveyed. Thereby, it can print on the articles | goods 2 conveyed by a line.

  The present invention can be used for an image forming apparatus and an image forming system for printing an article on a conveyance line with ink.

DESCRIPTION OF SYMBOLS 100 Image forming system 1 Image forming apparatus 2 Article 21 Printing surface 3 Conveying device 4 Control part 43 Memory | storage part 44 Speed sensor 47 Reading apparatus 46 Space | interval sensor 49 Space | interval control member 410 Contact sensor 5 Head 51 Nozzle 5B Nozzle block 6 Moving part 61 1st 1 moving mechanism 62 second moving mechanism 63 third moving mechanism 7 cap unit 9 operation panel 81 cleaning member 82 cleaning unit D1 printing data D2 image data D3 print setting information D4 definition data

Claims (16)

A head that includes nozzles arranged in a row, and prints an image by ejecting ink from the nozzles onto a printing surface of an article based on image data;
A moving unit for moving the head in at least two axial directions;
A control unit for controlling the moving unit,
Each said axial direction is orthogonal,
One of the two axial directions is an Z-axis direction that is a depth direction when the printing surface is a front surface. The nozzles are arranged along the Y-axis direction, which is the height direction when the printing surface is the front surface,
The moving unit includes a first moving mechanism, a second moving mechanism, and a third moving mechanism,
The controller is
Moving the head to the first moving mechanism in the Z-axis direction;
Moving the head to the second moving mechanism in the Y-axis direction, moving the head to the third moving mechanism in the X-axis direction, which is the width direction when the print surface is the front,
The image forming apparatus according to claim 1. When printing the printing surface based on a plurality of image data,
The image forming apparatus according to claim 2, wherein the control unit varies the position of the head in the Y-axis direction for each image. When printing on the article that is stopped,
The image forming apparatus according to claim 2, wherein the control unit moves the head to the moving unit in the X-axis direction during ink ejection. When printing on the article moving along the X-axis direction,
5. The image forming apparatus according to claim 2, wherein the control unit fixes the position of the head in the X-axis direction to the moving unit during ink ejection. 6. When printing on the article moving along the X-axis direction,
5. The control unit according to claim 2, wherein the control unit moves the head to the moving unit in the X-axis direction so that a relative speed between the article and the head is constant. The image forming apparatus described. A speed sensor for detecting a moving speed of the article in the X-axis direction;
The controller is
Based on the output of the speed sensor, recognize the moving speed,
Based on the recognized moving speed, a moving distance of the article during a reference period of ink discharge is determined,
Based on the resolution, one dot width, which is the width of one dot in the X-axis direction,
Moving the head to the moving unit along the X-axis direction so that the relative speed of the article and the head is a speed obtained by dividing the one-dot width by the reference period;
The image forming apparatus according to claim 6, wherein ink is ejected to the head at the reference period. The controller is
As the relative speed between the article and the head increases, the head discharges ink so that the amount of ink discharged from the nozzle to be used per unit time increases.
6. The image forming apparatus according to claim 4, wherein the head causes ink to be ejected so that the amount of ink ejected from the nozzle to be used per unit time decreases as the relative speed decreases. A cap portion for covering an exposed surface of the head from which the nozzle is exposed and preventing drying of the ink;
When a predetermined evacuation condition is met,
The control unit moves the head to the moving unit toward the retracted position,
The image forming apparatus according to claim 1, wherein the retracted position is a position where the head is fitted into the cap portion and the exposed surface is covered with the cap portion. Including an operation panel that accepts operations,
The evacuation condition is one or more of the following: the operation panel has received an instruction to evacuate the head, a predetermined evacuation time has been reached, and printing has been completed. The image forming apparatus according to claim 8. A cleaning member for cleaning the nozzle,
When predetermined cleaning conditions are met,
The image forming apparatus according to claim 1, wherein the control unit moves the head to the moving unit so that the nozzle is rubbed by the cleaning member. Including an operation panel that accepts operations,
The cleaning conditions include that the operation panel has received a cleaning instruction for the nozzle, that a predetermined cleaning time has been reached, that a predetermined number of items have been printed after starting printing or immediately before cleaning, and The image forming apparatus according to claim 10, wherein one or a plurality of printings are completed.   12. The image forming apparatus according to claim 10, further comprising: a cleaning unit that causes a cleaning liquid to flow through the cleaning member before rubbing the nozzle and that cleans the cleaning member after cleaning with the cleaning liquid. An image forming apparatus according to any one of claims 1 to 12,
An image forming system comprising: a conveying device configured to convey the article in an X-axis direction which is a width direction when the printing surface is a front surface. The transport device stops the article before the head starts printing,
The head prints on the stationary article;
The image forming system according to claim 13, wherein when the printing by the head is completed, the transport device resumes transport of the article. The transport device transports the article at a constant speed,
The image forming system according to claim 13, wherein the head prints on the article being conveyed.

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