JP2022052561A - Image forming method and image forming apparatus - Google Patents

Abstract

To provide a technique that prevents formation of streak-like unevenness at the joint of unit areas when an image is formed in multi-path printing.SOLUTION: A control unit 12 applies ink, through main scanning SC3, to a first unit area 91 and a first joint area 901 adjacent to a +X side to the first unit area 91 on a surface 9a of a wiring board 9. After completion of the main scanning SC3, the control unit 12 moves a head unit 40 toward the +X side, and applies ink, through main scanning SC4, to the first joint area 901 and a second unit area 92 adjacent to the +X side to the first joint area 901. After completion of the main scanning SC4, the control unit 12 moves the heat unit 40 toward a -X side, and applies ink, through main scanning SC5, to the first unit area 91 and the first joint area 901.SELECTED DRAWING: Figure 6

Description

The present invention relates to an image forming method and an image forming apparatus.

A resist film may be formed on the wiring board for the purpose of protecting the conductive pattern of the wiring board. The resist film also has a role of preventing the solder from adhering to areas such as conductor wiring during the solder application in the subsequent process, and is also called "solder resist". As a method for forming a resist film, a method of ejecting a droplet of solder resist ink toward a wiring board by an inkjet method is known. Such techniques are disclosed, for example, in Patent Documents 1 and 2.

Japanese Unexamined Patent Publication No. 9-283893 Japanese Unexamined Patent Publication No. 2008-4820

In an inkjet image forming apparatus, ink is transferred to a substrate by main scanning in which ink is ejected from each nozzle while moving a head portion having a plurality of nozzles arranged in the sub-scanning direction with respect to the substrate in the main scanning direction. Granted. Here, in order to prevent image quality deterioration due to variations in ejection characteristics among a plurality of nozzles, multi-pass printing may be performed. In multi-pass printing, each time the main scan is performed, the head portion is moved in the sub-scan direction with a feed amount smaller than the width that can be recorded in one main scan, and the main scan is performed multiple times for the same unit area. Go and complete the image. In multi-pass printing, the main scan is performed so that the joints between the unit areas overlap.

Further, in order to increase the resolution in the sub-scanning direction, an image may be formed by an interlace method. In the interlaced method, the head portion is moved in the sub-scanning direction with a predetermined and relatively narrow feed amount.

By the way, on the surface of the base material, there may be a difference in the fixing of the ink applied later between the region to which the ink is applied first and the region to which the ink is not applied. For example, solder resist inks generally have high fluidity. Therefore, there is a possibility that the ink applied earlier spreads and mixes with the ink applied later, so that the ink applied later forms unevenness or the like. Further, even when the ink is cured by UV irradiation or the like during the main scanning, there is a possibility that the ink applied later may form irregularities or the like depending on the surface shape and the curing condition of the ink.

For example, when an image is formed by multi-pass printing, a plurality of main scans are performed for each unit area. Therefore, the time from when ink is applied to one unit area to when ink is applied to adjacent unit areas becomes longer according to the number of main scans for the unit area. Then, at the joint between two adjacent unit regions, the ink applied later interferes with the ink applied earlier, so that unevenness is likely to be formed. When unevenness is formed in the ink due to interference between the inks, there is a possibility that streak-like unevenness extending in the main scanning direction is finally formed at the joint between the unit regions.

An object of the present invention is to provide a technique for suppressing the formation of streak-like unevenness at a joint between unit regions when an image is formed by multi-pass printing.

In order to solve the above problems, the first aspect is to move the head portion having a plurality of nozzles arranged in the sub-scanning direction to the base material in the main scanning direction from the plurality of nozzles to the base material. An image forming method for forming an image on the substrate by ejecting ink, wherein (a) the surface of the substrate is formed into a first unit region and the first unit region by the main scanning. On the other hand, after the step of applying ink to the first joint region adjacent to one side in the sub-scanning direction and (b) the step (a), the head portion is moved to one side in the sub-scanning direction with respect to the substrate. After the step (c) and the step (b), the surface of the base material is adjacent to the first joint region and one side in the sub-scanning direction with respect to the first joint region by the main scan. A step of applying ink to the second unit region to be used, (d) a step of moving the head portion to the other side in the sub-scanning direction with respect to the base material after the step (c), and (e) the above. The step (d) includes a step of applying ink to the first unit region and the first joint region by the main scanning.

The second aspect is the image forming method of the first aspect, in which (f) the step of applying ink to the second unit region and the first joint region by the main scanning after the step (c). Including further.

The third aspect is the image forming method of the second aspect, further including (g) a step of moving the head portion to one side in the sub-scanning direction after the step (e), and the step (f). Is executed after the step (g).

The fourth aspect is the image forming method of the second aspect, in which the step (f) is executed before the step (d).

A fifth aspect is the image forming method according to any one of the second to fourth aspects, wherein (h) the step of moving the head portion to one side in the sub-scanning direction after the step (c). (I) After the step (h), the second seam region adjacent to one side in the sub-scanning direction with respect to the second unit region and the second seam on the surface of the base material by the main scanning. A step of applying ink to a third unit region adjacent to one side in the sub-scanning direction with respect to the region, and (j) a step of moving the head portion to the other side in the sub-scanning direction after the step (i). , The step (f) is executed after the step (j), and in the step (c) and the step (f), the ink is applied to the second joint region.

A sixth aspect is the image forming method according to any one of the first to fifth aspects, and the step (a) cures the ink applied to the first unit region and the first joint region. Includes the step of irradiating energy rays.

A seventh aspect is the image forming method according to any one of the first to sixth aspects, in which the position where the ink is applied on the substrate in the step (c) is the base in the step (a). It is displaced in the sub-scanning direction by a distance smaller than the distance between the nozzles with respect to the position where the ink is applied on the material.

The eighth aspect is the image forming method according to any one of the first to seventh aspects, wherein the position of the head portion in the step (c) is relative to the position of the head portion in the step (a). Therefore, it is deviated in the sub-scanning direction by a distance equal to or longer than the distance between the nozzles.

A ninth aspect is an image forming apparatus, the holding portion holding the base material, a head portion having a plurality of nozzles arranged at intervals in the sub-scanning direction, and the base material held by the holding portion. On the other hand, by controlling the moving mechanism for moving the head portion in the main scanning direction and the sub-scanning direction, and the moving mechanism and the head portion, the head portion is moved in the main scanning direction with respect to the base material. The control unit is provided with a control unit for ejecting ink from the plurality of nozzles while performing a main scan for causing the main scan. After the process of applying ink to the first joint region adjacent to one side in the sub-scanning direction with respect to the first unit region and (B) the process (A), the head portion is subordinated to the base material. After the process of moving to one side in the scanning direction and (C) the process (B), the surface of the base material is subordinated to the first joint region and the first joint region by the main scan. A process of applying ink to a second unit region adjacent to one side in the scanning direction, and (D) a process of moving the head portion to the other side of the sub-scanning direction with respect to the substrate after the process (C). And (E), after the process (D), it is possible to execute a process of applying ink to the first unit region and the first joint region by the main scan.

According to the image forming method of the first aspect, by not performing the main scan for the first unit region and the first joint region continuously, the main scan for the second unit region and the first joint region is the main scan for the first joint region. The surface shape is less likely to differ between the ink applied to the ink and the ink applied to the second unit region. As a result, it is possible to suppress the formation of streak-like unevenness in the first joint region.

According to the image forming method of the second aspect, an image can be formed by a plurality of main scans for both the first unit region and the second unit region.

According to the image forming method of the third aspect, since the main scan of the first unit region and the main scan of the second unit region are alternately performed, the image is uniformly displayed with respect to the first unit region and the second unit region. Can be formed.

According to the image forming method of the fourth aspect, after the main scan of the second unit region is performed, the main scan of the second unit region is performed again before the main scan of the first unit region is performed. As a result, the amount of movement of the head portion in the sub-scanning direction is reduced, so that the speed of image formation can be improved.

According to the image forming method of the fifth aspect, it is possible to suppress the formation of streak-like unevenness in the second joint region between the second unit region and the third unit region.

According to the image forming method of the sixth aspect, the ink adhering to the first unit region can be cured.

According to the image forming method of the seventh aspect, the resolution in the sub-scanning direction can be increased by forming the image by shifting it smaller than the nozzle spacing.

According to the image forming method of the eighth aspect, deterioration of image quality due to variation in ejection characteristics among a plurality of nozzles can be suppressed.

According to the image forming apparatus of the ninth aspect, the first joint region is the main scan for the second unit region and the first joint region by not continuously performing the main scan for the first unit region and the first joint region. The surface shape is less likely to differ between the ink applied to the ink and the ink applied to the second unit region. As a result, it is possible to suppress the formation of streak-like unevenness in the first joint region.

It is a perspective view which shows the image forming apparatus of 1st Embodiment. It is a figure which shows the lower surface of the head part. It is a figure which shows the structure of the control part. It is a top view which conceptually shows the area arrangement on the surface of a wiring board. It is a top view which conceptually shows the main scan with respect to the surface of a wiring board. It is a figure which conceptually shows how the ink is applied to the 1st joint area. It is a figure which conceptually shows the main scan with respect to the surface of a control board which concerns on a comparative example. It is a figure which conceptually shows the state which ink is applied to the 1st joint area which concerns on a comparative example. It is a schematic diagram which shows the behavior after the ink droplet has landed on the surface of a wiring board. It is a top view which conceptually shows the main scan with respect to the surface of the wiring board which concerns on 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the components described in this embodiment are merely examples, and the scope of the present invention is not limited to them. In the drawings, the dimensions and numbers of each part may be exaggerated or simplified as necessary for easy understanding.

Further, for convenience of explanation, arrows indicating X, Y, and Z axes orthogonal to each other may be added to the drawings. The Z direction is parallel to the vertical direction, and the X and Y directions are parallel to the horizontal plane. Further, in the following description, the direction in which the tip of each arrow points is the + (plus) direction, and the opposite direction is the- (minus) direction. The + Z side is the upper side, and the -Z side is the lower side. The Y direction corresponds to the main scanning direction. The X direction corresponds to the sub-scanning direction.

<1. First Embodiment>
FIG. 1 is a perspective view showing the image forming apparatus 1 of the first embodiment. The image forming apparatus 1 forms an image (pattern) of a resist film on the surface 9a of a printed wiring board (hereinafter, simply referred to as “wiring board”) 9 with, for example, solder resist ink. The image forming apparatus 1 forms an image by an inkjet method. The wiring board 9 is, for example, a rectangular plate-shaped base material made of a glass epoxy resin. However, the wiring board 9 may be a flexible sheet-like member or the like. The resist film protects, for example, the conductive pattern on the wiring board 9. Conductive patterns include, for example, wiring or lands. The resist film may not be formed in the region where the solder paste is applied in the subsequent process or in other regions where the resist film should not be provided.

The image forming apparatus 1 includes an apparatus main body 10 and a control unit 12. The apparatus main body 10 includes a stage 20, a moving mechanism 30, a head unit 40, a tank 50, and a UV irradiation unit 60.

The stage 20 is an example of a holding portion that holds the wiring board 9. The stage 20 has an upper surface on which the wiring board 9 is placed. For example, a large number of holes are formed on the upper surface of the stage 20. Each hole is connected to a suction device (not shown). By sucking air from each hole, the wiring board 9 is sucked onto the upper surface of the stage 20. The wiring board 9 may be attracted to the groove by connecting the holes on the upper surface of the stage 20 with a groove. Further, the upper surface of the stage 20 may be made of a porous member, and the wiring board 9 may be adsorbed via the porous member. Further, the stage 20 may be provided with a holder for mechanically holding the wiring board 9.

The moving mechanism 30 moves the head portion 40 relative to the wiring board 9 in the X direction and the Y direction. The moving mechanism 30 includes, for example, a main scanning moving unit 31 and a sub-scanning moving unit 33. The main scanning moving unit 31 moves the wiring board 9 with respect to the head unit 40 in the Y direction (main scanning direction) parallel to the surface 9a of the wiring board 9. The sub-scanning moving unit 33 moves the head unit 40 in the X direction (sub-scanning direction) with respect to the wiring board 9 held on the stage 20. The X direction is perpendicular to the Y direction and parallel to the surface 9a of the wiring board 9. As the driving mechanism of the main scanning moving unit 31 and the sub-scanning moving unit 33, for example, a ball screw mechanism including a motor or a linear motor mechanism may be adopted.

The moving mechanism 30 may be configured to move the head portion 40 in both the X direction and the Y direction. Further, the moving mechanism 30 may be configured to move the stage 20 in both the X direction and the Y direction.

The head portion 40 ejects minute droplets of solder resist ink (hereinafter, simply referred to as “ink”) toward the moving wiring board 9. The tank 50 stores the ink supplied to the head portion 40. Ink is supplied from the tank 50 to the head portion 40 via the tube 51. The ink supplied to the head portion 40 is, for example, an ink that is cured by irradiation with energy rays (radiation including particle beams and electromagnetic waves), and specifically, UV ink.

FIG. 2 is a diagram showing a lower surface 41 of the head portion 40. The head portion 40 has a plurality of nozzles 43 arranged at equal intervals in the X direction. The plurality of nozzles 43 are provided on the lower surface 41 of the head portion 40. In the example shown in FIG. 2, a plurality of nozzles 43 are arranged in a straight line, but this is not essential. The plurality of nozzles 43 may be arranged in a stepped or staggered manner, for example. In the following description, the distance (pitch) between two adjacent nozzles 43 is defined as "d1". Further, among the plurality of nozzles 43, the distance between the nozzle 43 on the most −X side and the nozzle 43 on the most + X side is set to “d2”. The head portion 40 has (d2 / d1) + 1 nozzles.

The head portion 40 ejects ink droplets from each nozzle 43 by an inkjet method. The ink is ejected in the −Z direction toward the surface 9a of the wiring board 9. As the inkjet method, for example, a piezo method or a thermal method can be adopted.

While the main scanning moving unit 31 moves the stage 20 holding the wiring board 9 in the Y direction, the head unit 40 ejects ink from a plurality of nozzles 43, so that the ink extends in the Y direction of the wiring board 9. Is given. Hereinafter, the movement of the head portion 40 with respect to the wiring board 9 in the Y direction is referred to as “main scanning”. Further, the movement of the head portion 40 with respect to the wiring board 9 in the X direction is referred to as "sub-scanning".

The UV irradiation unit 60 includes a UV lamp. The UV irradiation unit 60 is located on the + Y side of the head unit 40. The UV irradiation unit 60 is fixed to the head unit 40. The sub-scanning moving unit 33 moves the UV irradiation unit 60 together with the head unit 40 in the X direction. The UV irradiation unit 60 cures the ink applied to the wiring board 9 by the head unit 40 by irradiating the wiring board 9 with ultraviolet rays. The UV irradiation unit 60 is an example of an irradiation unit that irradiates energy rays.

In order to cure the ink in the UV irradiation unit 60, in the main scan, the wiring board 9 held by the stage 20 is moved in the + Y direction with respect to the head unit 40. As a result, in one main scan, the head portion 40 can apply ink to the wiring board 9, and the ink applied to the wiring board 9 can be cured by the ultraviolet rays of the UV irradiation unit 60. It is not essential that the UV irradiation unit 60 is fixed to the head unit 40. For example, the UV irradiation unit 60 may be provided separately from the head unit 40.

The UV irradiation unit 60 may irradiate the wiring board 9 with ultraviolet rays having the same width in the X direction as the width d2 described later. Further, the UV irradiation unit 60 may irradiate the wiring board 9 with ultraviolet rays having a width slightly wider in the X direction and the −X direction than the width d2.

FIG. 3 is a diagram showing the configuration of the control unit 12. The control unit 12 has, for example, a configuration as a computer. Specifically, the control unit 12 includes a processor 71, a RAM 72, a fixed disk 73, an equipment interface 74, a communication unit 75, and a bus 77. The processor 71 is electrically connected to the RAM 72, the fixed disk 73, the device interface 74, and the communication unit 75 via the bus 77.

The processor 71 is composed of, for example, a CPU or a GPU. The processor 71 performs various arithmetic processes. The fixed disk 73 is a non-transient storage medium for storing various information, such as a hard disk.

A display 81, an input device 82, and a reading device 83 are connected to the device interface 74. The display 81 displays character information and image information. The input device 82 includes a mouse and a keyboard that receive input from the operator. The reading device 83 reads the information recorded on the recording medium 84. The recording medium 84 is, for example, an optical disk, a magnetic disk, a magneto-optical disk, or a memory card. The communication unit 75 transmits / receives a signal to / from the device main body 10. The control unit 12 controls the moving mechanism 30 and the head unit 40 by outputting a control signal to the apparatus main body 10.

The control unit 12 reads the program P from the recording medium 84 in advance via the reading device 83, and stores the program P on the fixed disk 73. The program P may be stored in the fixed disk 73 via the network. The processor 71 executes arithmetic processing while using the RAM 72 according to the program P.

<About image formation processing>
FIG. 4 is a plan view conceptually showing the main scan of the wiring board 9 with respect to the surface 9a. As shown in FIG. 4, the width d3 in the X direction of the surface 9a of the wiring board 9 is larger than the distance d2 (see FIG. 2). Therefore, the control unit 12 defines the first unit region 91 and the second unit region 92 with respect to the surface 9a of the wiring board 9, and generates image data corresponding to each region. Then, the control unit 12 forms an image in the first unit region 91 and the second unit region 92 based on each image data.

Here, a center line C that equally divides the surface 9a of the wiring board 9 in the X direction is defined. One side of the surface 9a of the wiring board divided by the center line C is referred to as a one-sided division region 9L, and the other side is referred to as the other division region 9R.

The region near the center line C has a region recorded by the head portion 40 located in the one division region 9L and the head portion 40 located in the other division region 9R. This region is referred to as the first joint region 901. On the other hand, the region obtained by removing the first joint region 901 from the divided region 9L is referred to as the first unit region 91. On the other hand, the region obtained by removing the first joint region 901 from the divided region 9R is referred to as the second unit region 92. The first unit area 91 is recorded by the head portion 40 located in the divided area 9L. The second unit region 92 is recorded by the head portion 40 located in the other divided region 9R.

The first joint region 901 is adjacent to one side in the X direction with respect to the first unit region 91. Further, the second unit region 92 is adjacent to the other side in the X direction with respect to the first joint region 901.

Further, the control unit 12 may form an image by multi-pass printing. Specifically, the first unit region 91 and the second unit region 92 are subjected to four main scans each, for a total of eight main scans (main scans SC1 to SC8). Further, the control unit 12 shifts the head unit 40 with a feed amount smaller than the nozzle spacing d1 to form an image at a pitch finer than the nozzle spacing d1 in the sub-scanning direction.

The first joint region 901 is wired by the main scan (main scan SC3, SC5, SC7) for the first unit region 91 and the main scan (main scan SC2, SC4, SC6) for the second unit region 92. An image is formed on the surface 9a of the substrate 9. In FIG. 5, the application range 53 shown at the bottom indicates a range in which the head unit 40 applies ink in each of the main scans SC1 to SC8.

FIG. 6 is a diagram showing how ink is applied to the first joint region 901. FIG. 6 shows the states of the main scans SC1 to SC8 executed by the control unit 12 in order from the top. As described above, the main scans SC1, SC3, SC5, SC7 correspond to the process of applying ink to the first unit region 91, and the main scans SC2, SC4, SC6, SC8 apply ink to the second unit region 92. Corresponds to the process of giving.

In FIG. 6, the head portion 40 includes 10 nozzles a to j, and images are recorded on the surface 9a by selectively using these nozzles a to j.

Further, in FIG. 6, in each of the main scans SC1 to SC8, the dot line DL1 being formed by applying ink is indicated by an arrow extending in the + Y direction (main scan direction). Further, in the main scans SC2 to SC8, the dot lines DL2 of the ink formed by the previously executed main scans SC1 to SC7 are shown by solid lines. The spacing between the dot lines DL1 and the dot line DL2 ideally corresponds to the nozzle spacing d1. In addition, since the ink is actually applied only to the necessary portion, the ink is not necessarily applied linearly.

Further, in FIG. 6, the arrow extending in the X direction (sub-scanning direction) shown between each of the main scans SC1 to SC8 conceptually indicates the sub-scans S1 to S7 of the head portion 40.

First, the control unit 12 uses six nozzles e to j located on the + X side of the ten nozzles a to j to cover the entire range of the first unit region 91 with a plurality of dot lines DL1. (Main scan SC1). In the main scan SC1, the dot line DL1 is not formed in the first joint region 901 and the second unit region 92.

When the control unit 12 completes the main scan SC1, the head unit 40 moves the head unit 40 to the + X side (secondary scan S1). In the sub-scanning S1, the control unit 12 shifts the nozzle a located on the most −X side of the head unit 40 to the + X side from the boundary between the first unit region 91 and the first joint region 901 to 1/4 of the nozzle spacing d1. Place it in a position that is offset by the size of.

After moving the head unit 40 to the + X side, the control unit 12 uses all 10 nozzles a to j to cover the entire range of the second unit region 92 and the entire range of the first joint region 901. Dot line DL1 is formed (main scan SC2). In this example, the main scan SC2 forms four dot lines DL1 in the first seam region 901. The main scans SC1 and SC2 seamlessly form the dot line DL2 at the pitch of the nozzle spacing d1 over the three regions of the first unit region 91, the first joint region 901, and the second unit region 92.

When the control unit 12 completes the main scan SC2, the head unit 40 returns the head unit 40 to the start position of the main scan and moves it in the −X direction (the other side in the sub scan direction) (sub scan S2).

When the sub-scanning S2 is completed, the control unit 12 uses the seven nozzles d to j located on the + X side of the ten nozzles a to j to use the entire range of the first unit region 91 and the first position. A plurality of dot lines DL1 are formed in a part of the one joint region 901 (main scan SC3).

The position of the head portion 40 in the main scan SC 3 is deviated from the position of the head portion 40 in the main scan SC 1 to the + X side by a distance Δx. The distance Δx is a value (= N · d1 + d1 / 4) that is the sum of the value obtained by multiplying the nozzle spacing d1 by an integer (= N · d1) and the distance d1 / 4 smaller than the nozzle spacing. In the example shown in FIG. 6, Δx = d1 + d1 / 4 (that is, N = 1). As a result, in the main scan SC3, the dot line DL1 is formed at a position shifted to the + X side (d1 / 4) with respect to the dot line DL2 formed by the main scan SC1. The control unit 12 shifts the nozzle group for ejecting ink by (N-1) to the −X side. As a result, as shown in FIG. 6, in this example, the main scan SC3 forms one dot line DL1 at the −X side end portion in the first joint region 901.

The size of the distance Δx is appropriately set based on the ratio of the image resolution and the head resolution. For example, in the present embodiment, the distance Δx is set to d1 + d1 / 4 based on the ratio of the image resolution of 2400 dpi and the head resolution of 600 dpi.

When the control unit 12 completes the main scan SC3, the head unit 40 returns the head unit 40 to the start position of the main scan and moves it to the + X side (one side in the sub scan direction) (sub scan S3).

When the sub-scanning S3 is completed, the control unit 12 uses eight nozzles a to i located on the −X side of the ten nozzles a to j to cover the entire range of the second unit region 92. A dot line DL1 is formed in a part of the first joint region 901 (main scan SC4). In this example, the main scan SC4 forms three dot lines DL1 in the first seam region 901. The position of the head portion 40 in the main scan SC 4 is deviated from the position of the head portion 40 in the main scan SC 2 to the + X side by a distance Δx.

The main scans SC3 and SC4 make d1 on the + X side with respect to each dot line DL2 formed by the main scans SC1 and SC2 over the entire range of the first unit region 91, the first joint region 901, and the second unit region 92. The dot line DL2 is formed at a position separated by 4/4.

When the control unit 12 completes the main scan SC4, the head unit 40 returns the head unit 40 to the start position of the main scan and moves it to the −X side (secondary scan S4).

When the sub-scanning S4 is completed, the control unit 12 uses eight nozzles c to j located on the + X side of the ten nozzles a to j to cover the entire range of the first unit region 91 and the first unit. A dot line DL1 is formed on a part of the one joint region 901 (main scan SC5). The position of the head portion 40 in the main scan SC 5 is deviated from the position of the head portion 40 in the main scan SC 3 to the + X side by a distance Δx. Therefore, in the main scan SC5, the dot line DL1 is formed at a position shifted by d1 / 4 to the + X side with respect to the dot line DL2 formed by the main scan SC3. Further, in the main scanning SC5, two dot lines DL1 are formed in the first joint region 901.

When the control unit 12 completes the main scan SC5, the head unit 40 returns the head unit 40 to the start position of the main scan and moves it to the + X side (secondary scan S5).

When the sub-scanning S5 is completed, the control unit 12 uses eight nozzles a to h located on the −X side of the ten nozzles a to j to cover the entire range of the second unit region 92. A dot line DL1 is formed on a part of the first joint region 901 (main scan SC6).

In the main scan SC6, the dot line DL1 is formed at a pitch of d1 at a position separated by d1 from the dot line DL2 formed by the main scan SC5 on the + X side. That is, the main scans SC5 and SC6 form dot lines DL2 at the pitch of d1 in all of the first unit region 91, the first joint region 901, and the second unit region 92. By the main scans SC5 and SC6, d1 on the + X side with respect to each dot line DL2 formed by the main scans SC3 and SC4 over the entire range of the first unit region 91, the first joint region 901, and the second unit region 92. The dot line DL2 is formed at a position separated by 4/4. The position of the head portion 40 in the main scan SC 6 is deviated from the position of the head portion 40 in the main scan SC 4 to the + X side by a distance Δx.

When the control unit 12 completes the main scan SC6, the head unit 40 returns the head unit 40 to the start position of the main scan and moves it to the −X side (secondary scan S6). When the sub-scanning S6 is completed, the control unit 12 uses nine nozzles b to h located on the + X side of the ten nozzles a to j to cover the entire range of the first unit region 91. Dot line DL1 is formed in the entire range of the first joint region 901 (main scan SC7). The position of the dot line DL1 formed in the main scan SC7 is shifted to the + X side by d1 / 4 with respect to the dot line DL1 formed in the main scan SC5. Further, in the main scanning SC7, three dot lines DL1 are formed in the first joint region 901.

When the control unit 12 completes the main scan SC7, the head unit 40 returns the head unit 40 to the start position of the main scan and moves it to the + X side (secondary scan S7). When the sub-scanning S7 is completed, the control unit 12 uses seven nozzles a to g located on the −X side of the ten nozzles a to j to cover the entire range of the second unit region 92. The dot line DL1 of the book is formed (main scan SC8). That is, in the main scan SC8, the dot line DL1 is not formed in the first unit region 91 and the first joint region 901. In the main scan SC8, a plurality of dot lines DL1 are formed at positions separated by d1 on the + X side from the dot line DL2 formed by the main scan SC7. The main scans SC7 and SC8 form dot lines DL2 at a pitch of d1 over the entire range of the first unit region 91, the first seam region 901, and the second unit region 92. The position of the head portion 40 in the main scan SC 8 is deviated from the position of the head portion 40 in the main scan SC 6 to the + X side by a distance Δx.

By the above main scans SC1 to SC8, the dot line DL2 is formed at a pitch of d1 / 4 in the X direction over the entire range of the first unit region 91, the first joint region 901, and the second unit region 92. .. In the main scans SC3, SC5, and SC7 for the first unit region 91, the dot line DL1 is formed in a portion different from the main scans SC2, SC4, and SC6 for the second unit region 92 with respect to the first joint region 901.

<Effect>
FIG. 7 is a diagram conceptually showing the main scan with respect to the surface of the control board according to the comparative example. FIG. 8 is a diagram conceptually showing how ink is applied to the first joint region according to the comparative example. In the comparative example shown in FIGS. 7 and 8, first, the main scan SC and the sub scan S are alternately executed for the first unit region 91. That is, the sub-scan S1 is performed after the main scan SC1, the S3 is performed after the main scan SC3, the S5 is performed after the main scan SC5, and then the main scan SC7 is performed.
Next, the main scan SC and the sub scan S are alternately executed for the second unit region 92. That is, the main scan SC2 is executed after the sub-scan S2, the main scan SC4 is executed after the sub-scan S4, the main scan SC6 is executed after the sub-scan S6, and the main scan SC8 is executed after the sub-scan S8. The amount of movement of the head portion 40 in the sub-scanning direction in each sub-scanning S1 to S8 is a distance Δx.

In the case of this comparative example, ink is applied to the first joint region 901 by a total of three main scans SC3, SC5, SC7 by the time the first main scan SC2 for the second unit region 92 is started. Ink. That is, since the main scans SC3, SC5, and SC7 are continuously performed, a relatively long time elapses from the start of applying ink to the first joint region 901 until the start of the main scan SC2. Become. Then, for example, in the main scanning SC2, the surface shape is likely to be different between the ink applied to the first joint region 901 and the ink applied to the second unit region 92. Therefore, in the first joint region 901, there is a possibility that streak-like unevenness extending in the main scanning direction is finally formed.

On the other hand, in the present embodiment, as shown in FIGS. 5 and 6, the control unit 12 performs the main scan SC4 after the main scan SC3, and then performs the main scan SC5. Further, the control unit 12 performs the main scan SC6 after the main scan SC5, and then performs the main scan SC7. That is, it is suppressed that the main scans SC3, SC5, and SC7 for the first unit region 91 and the first joint region 901 are continuously performed. By doing so, in each of the main scans SC3, SC5, and SC7, the surface shape is less likely to be different between the ink applied to the first joint region 901 and the ink applied to the second unit region 92. .. Therefore, it is possible to suppress the formation of streak-like unevenness in the first joint region 901.

Next, the behavior of the ink droplets on the surface 9a of the wiring board 9 in the present embodiment and the modification will be described with reference to FIG. FIG. 9 is a schematic cross-sectional view of the droplet ink droplets dr1 and dr2 that have landed on the surface 9a.

9a to 9d show a state in which the preceding ink droplet dr2 landed after the preceding ink droplet dr1 that landed first was irradiated with ultraviolet rays twice. Further, FIGS. 9e to 9g show a state in which the subsequent ink droplet dr2 lands after the preceding ink droplet dr1 is irradiated with ultraviolet rays once.

FIG. 9a is a schematic diagram immediately after the ink droplet dr1 lands on the dot line L1 on the surface 9a. The ink droplet dr1 is then semi-cured by being irradiated with the ultraviolet rays of the UV irradiation unit 60 (FIG. 9b).

The ink droplet dr1 may be affected by ultraviolet rays for curing the ink droplets of the other dot line L. As shown in FIG. 9c, the ink droplet dr1 is further cured by receiving ultraviolet rays for curing the ink droplets of the other dot line L. After that, another ink droplet dr2 lands on the adjacent dot line L2 adjacent to the dot line L1 (FIG. 9d).

The dot line spacing (nozzle pitch) in the present embodiment and the modification is set to a distance substantially equal to or smaller than twice the radius of the ink droplet after landing. For example, the dot line spacing is set to 10 μm and the ink droplet radius is set to 20 μm. Therefore, the two ink droplets that land on the adjacent dot lines interfere with each other. In the examples of FIGS. 9d and 9g, the peripheral portions of the ink droplet dr1 of the dot line L1 and the ink droplet dr2 of the dot line L2 overlap each other. The degree of interference between the two ink droplets dr1 and dr2 is affected by the degree of curing of the preceding ink droplet dr1. That is, when the preceding ink droplet dr1 is irradiated with ultraviolet rays a large number of times and curing is progressing, the two ink droplets dr1 and dr2 are difficult to mix (see FIG. 9d). On the other hand, when the preceding ink droplet dr1 is irradiated with ultraviolet rays only a few times and is semi-cured, the two ink droplets dr1 and dr2 are easily mixed (see FIG. 9g).

From the above viewpoint, in the recording area, the adjacent dot line during the period from the landing of the preceding ink droplet on each dot line DL to the landing of the succeeding ink droplet on the adjacent dot line DL adjacent to the dot line DL. It is desirable to make the number of UV irradiations on the DL as uniform as possible. As a result, the degree of mutual interference between the preceding ink droplets of each dot line DL and the succeeding ink droplets of the adjacent dot line DL can be made uniform over the entire recording area, and unevenness in the recording area can be suppressed.

In the present embodiment previously described with reference to FIGS. 5 and 6, the head unit 40 and the UV irradiation unit 60 are largely moved in the sub-scanning direction each time the main scanning SC is performed once in the first joint region 901. Therefore, it is possible to avoid continuous irradiation of the adjacent dot line DL adjacent to the arbitrary dot line DL in the first joint region 901 with ultraviolet rays. Therefore, unevenness in the first joint region can be suppressed.

On the other hand, in the comparative examples of FIGS. 7 and 8, in the first joint region 901, the sub-scanning direction positions of the head portion 40 and the UV irradiation portion 60 hardly move while the main scanning SC is continuously performed. Therefore, the ultraviolet rays tend to be continuously irradiated to the adjacent dot line DL of the attention dot line DL in the first joint region 901. Therefore, there is a problem that unevenness is likely to occur in the first joint region.

In the example shown in FIGS. 5 and 6, the control unit 12 does not perform the main scan for the same unit region more than once in succession, and the main scan for the first unit region 91 and the second unit region 92. The main scan for is performed alternately. In this case, the difference in surface shape is less likely to occur between the inks applied to the first unit region 91, the first joint region 901, and the second unit region 92. Therefore, a homogeneous image can be formed on the surface 9a of the wiring board 9.

The order in which the main scans SC1 to SC8 are executed is not limited to that shown in FIG. For example, the control unit 12 may perform the main scans SC1 and SC2 after performing the main scans SC3 and SC4, or may perform the main scans SC1 and SC2 or the main scans SC3 and SC4 after performing the main scans SC5 and SC6. May be done. Further, the control unit 12 may perform the main scans SC1 and SC2, the main scans SC3 and SC4, or the main scans SC5 and SC6 after performing the main scans SC7 and SC8.

Further, the control unit 12 may perform the main scan for the same unit region twice in succession. For example, the control unit 12 may perform processing in the order of the main scans SC1, SC2, SC4, SC3, the main scans SC3, SC4, SC6, SC5, or the main scans SC5, SC6, SC8, SC7. good. In these cases, since the main scan SC2, SC4, the main scan SC4, SC6, or the main scan SC6, SC8 for the second unit region 92 are continuously performed, the head portion 40 of the head portion 40 in the X direction (secondary scan direction). The amount of movement is reduced. Therefore, the speed of image formation can be improved.

In the example shown in FIG. 6, ink is applied to different positions in the X direction (sub-scanning direction) in the main scans SC1 to SC8. However, in some of the main scans SC1 to SC8, the ink may be applied to the same position in the X direction. For example, the amount of ink per unit area can be increased by performing a plurality of main scans so as to apply ink to the same position in the Y direction (main scanning direction) and the X direction (secondary scanning direction). .. Further, in some of the main scans SC1 to SC8, ink may be applied to different positions in the Y direction (main scan direction). This makes it possible to increase the resolution of the image in the Y direction.

<2. 2nd Embodiment>
Next, the second embodiment will be described. In the following description, elements having the same functions as the elements already described may be given the same code or a code to which alphabetic characters are added, and detailed description may be omitted.

In the example shown in FIG. 5 or 6, the surface 9a of the wiring board 9 is divided into two regions (first unit region 91 and second unit region 92), but the surface 9a is divided into three or more regions. It may be divided. FIG. 10 is a diagram conceptually showing the main scan for the surface 9a of the wiring board 9 according to the second embodiment. In the example shown in FIG. 10, the surface 9a is divided into a first unit region 91, a second unit region 92, and a third unit region 93. The third unit region 93 is located on the + X side of the second unit region 92. The second seam region 902 is located between the second unit region 92 and the third unit region 93. The second joint region 902 is adjacent to the + X side with respect to the second unit region 92. The third unit region 93 is adjacent to + X with respect to the second joint region 902. The second joint region 902 is an area to which ink is applied by a plurality of main scans on the second unit region 92 and a plurality of main scans on the third unit region 93, similarly to the first joint region 901. ..

When forming an image on the surface 9a of the wiring board 9, the control unit 12 has a main scan for the first unit region 91 and the first joint region 901 (hereinafter referred to as “first overlapping main scan”) and a second unit. The main scan for the area 92, the first seam area 901, and the second seam area 902 (hereinafter referred to as "second overlapping main scan") and the main scan for the third unit area 93 and the second seam area 902 (hereinafter referred to as "second overlapping main scan"). , "Third overlapping main scan")) is executed a plurality of times. At this time, the control unit 12 performs the first overlap main scan, then the second overlap main scan, and then performs the first overlap main scan again. Further, the control unit 12 performs the second overlapping main scan, then the third overlapping main scanning, and then performs the second overlapping main scanning again. As a result, it is possible to suppress the formation of streak-like unevenness in the first joint region 901 and the second joint region 902.

Even when the surface 9a of the wiring board 9 is divided into four or more regions, the main scanning is performed in the same manner to prevent the formation of streak-like unevenness at the joints between the regions. can.

Although the invention has been described in detail, the above description is exemplary in all aspects and the invention is not limited thereto. It is understood that innumerable variations not illustrated can be assumed without departing from the scope of the present invention. Each configuration described in each of the above-described embodiments and modifications can be appropriately combined or omitted as long as they do not conflict with each other.

1 Image forming device 9 Wiring board 9a Surface 12 Control unit 20 Stage 30 Moving mechanism 31 Main scanning moving unit 33 Sub-scanning moving unit 40 Head unit 43 Nozzle 60 UV irradiation unit 83 Reading device 91 1st unit area 92 2nd unit area 93 3rd unit area 901 1st joint area 902 2nd joint area

Claims (9)

In the main scanning in which the head portion having a plurality of nozzles arranged in the sub-scanning direction is moved in the main scanning direction with respect to the substrate, ink is ejected from the plurality of nozzles to the substrate to produce an image on the substrate. Is an image forming method that forms
(A) A step of applying ink to a first unit region and a first joint region adjacent to one side in the sub-scanning direction with respect to the first unit region on the surface of the base material by the main scanning.
(B) After the step (a), a step of moving the head portion to one side in the sub-scanning direction with respect to the base material, and a step of moving the head portion to one side in the sub-scanning direction.
(C) After the step (b), the second unit adjacent to the first seam region and one side in the sub-scanning direction with respect to the first seam region on the surface of the base material by the main scan. The process of applying ink to the area and
(D) After the step (c), a step of moving the head portion to the other side in the sub-scanning direction with respect to the base material, and a step of moving the head portion to the other side in the sub-scanning direction.
(E) After the step (d), a step of applying ink to the first unit region and the first joint region by the main scanning, and a step of applying ink to the first joint region.
Image forming method including. The image forming method according to claim 1.
(F) A step of applying ink to the second unit region and the first joint region by the main scanning after the step (c).
A method of forming an image, further comprising. The image forming method according to claim 2.
(G) A step of moving the head portion to one side in the sub-scanning direction after the step (e).
Including
An image forming method in which the step (f) is executed after the step (g). The image forming method according to claim 2.
An image forming method in which the step (f) is executed before the step (d). The image forming method according to any one of claims 2 to 4.
(H) After the step (c), a step of moving the head portion to one side in the sub-scanning direction and a step of moving the head portion to one side in the sub-scanning direction.
(I) After the step (h), the second seam region adjacent to one side in the sub-scanning direction with respect to the second unit region and the second seam on the surface of the base material by the main scanning. The process of applying ink to the third unit area adjacent to one side in the sub-scanning direction with respect to the area, and
(J) After the step (i), a step of moving the head portion to the other side in the sub-scanning direction and a step of moving the head portion to the other side in the sub-scanning direction.
Including
The step (f) is executed after the step (j),
An image forming method in which ink is applied to the second joint region in the step (c) and the step (f). The image forming method according to any one of claims 1 to 5.
The step (a) is a step of irradiating an energy ray for curing the ink applied to the first unit region and the first joint region.
Image forming method including. The image forming method according to any one of claims 1 to 6.
In the step (c), the position where the ink is applied on the base material is sub-scanned by a distance smaller than the distance between the nozzles with respect to the position where the ink is applied on the base material in the step (a). Image formation method that is offset in the direction. The image forming method according to any one of claims 1 to 7.
An image in which the position of the head portion in the step (c) is displaced in the sub-scanning direction by a distance equal to or greater than the distance between the nozzles with respect to the position of the head portion in the step (a). Forming method. It is an image forming device
A holding part that holds the base material,
A head section with multiple nozzles lined up at intervals in the sub-scanning direction,
A moving mechanism that moves the head portion in the main scanning direction and the sub-scanning direction with respect to the base material held by the holding portion.
A control unit that ejects ink from the plurality of nozzles while performing a main scan that moves the head portion in the main scanning direction with respect to the base material by controlling the movement mechanism and the head portion.
Equipped with
The control unit
(A) A process of applying ink to the first unit region and the first joint region adjacent to one side in the sub-scanning direction with respect to the first unit region on the surface of the base material by the main scanning.
(B) After the process (A), a process of moving the head portion to one side in the sub-scanning direction with respect to the substrate, and a process of moving the head portion to one side in the sub-scanning direction.
(C) After the treatment (B), the second unit adjacent to the first seam region and one side in the sub-scanning direction with respect to the first seam region on the surface of the base material by the main scan. The process of applying ink to the area and
(D) After the process (C), a process of moving the head portion to the other side in the sub-scanning direction with respect to the substrate,
(E) After the process (D), a process of applying ink to the first unit region and the first joint region by the main scan.
An image forming device that is feasible.

Images