Inkjet printing device

Abstract

To suppress the occurrence of a bridging phenomenon on a printing surface.SOLUTION: An inkjet printing apparatus 1 includes an inkjet head 30 that moves in a main scanning direction Y at the time of printing; a filter chamber 33 provided on a path for supplying ink to an orifice 31a (nozzle) in the inkjet head 30; and a spherical body 50 placed on a head filter 34 in the filter chamber 33. The spherical body 50 has a diameter φ larger than the mesh of the head filter 34. The spherical body 50 is disposed on the head filter 34 so as to be rotatable by the movement of the inkjet head 30.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to inkjet printing devices. [Background technology]

[0002] Some inkjet printing devices have a filter chamber located in the ink supply path from the ink cartridge to the nozzles of the head unit. The filter chamber contains a filter, which ensures that ink that has been filtered to remove foreign matter is supplied to the head unit.

[0003] Patent Document 1 discloses that, in order to eliminate air bubbles in the filter chamber, a stirring member (plate, ball) is provided upstream of the filter in the ink flow direction to generate turbulence in the filter chamber. Patent Document 2 discloses that a float is disposed in a filter chamber to generate turbulence in the filter chamber, thereby suppressing clogging of the filter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 05-131645 [Patent Document 2] Patent No. 4911303 Summary of the Invention

[0005] Agitators and floating bodies only create turbulence in the ink flow, making it difficult to prevent bridging in the filter, which occurs when fine particles in the ink aggregate and form bridges that cover the filter openings, causing the filter to become clogged. In particular, so-called aggregation-type inks tend to easily generate aggregates of fine particles in the ink when exposed to external stimuli, making it difficult to prevent filter clogging due to the bridging phenomenon. Therefore, there is a need to be able to suppress the occurrence of the bridging phenomenon. [Means for solving the problem]

[0006] The present invention provides (1) an inkjet head that moves in a scanning direction during printing; a filter chamber provided on a path for supplying ink to the nozzles in the inkjet head; a rolling element mounted on the filter in the filter chamber, the rolling elements have a diameter larger than the mesh of the filter; The rollers move in the direction of the filter by the movement of the inkjet head. surface They are arranged so that they can be rolled over and moved randomly. of the rolling body on the surface of the filter Random movement causes aggregated particles to form on the surface of the filter. particle It is an inkjet printing device that disperses

[0007] (2) The rolling elements are spheres made of a non-magnetic metal.

[0008] (3) A plurality of the spheres are placed on the filter, The ratio of the projected area of the sphere to the area of the filter is 3% or more and 30% or less.

[0009] (4) A plurality of the spheres are placed on the filter, The total projected area of the spheres relative to the filter is 1 / 3 to 1 / 30 of the area of the filter.

[0010] (5) The ink is an ultraviolet curable ink.

[0011] (6) The ink is a support material ink used in three-dimensional modeling. [Effects of the Invention]

[0012] According to the present invention, the occurrence of the bridging phenomenon can be suppressed. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram illustrating an inkjet printing apparatus. [Figure 2] FIG. 2 is an enlarged view of a main part of the inkjet printing device. [Figure 3] FIG. 2 is a diagram schematically illustrating a cross section of an inkjet head. [Figure 4] 10A and 10B are diagrams illustrating the relationship between a head filter and a sphere. BEST MODE FOR CARRYING OUT THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described by taking as an example a case where it is applied to an inkjet printing apparatus 1 that prints on a medium M.

[0015] FIG. 1 is a schematic diagram illustrating an inkjet printing apparatus 1. As shown in FIG. FIG. 2 is an enlarged view of the carriage 3. As shown in FIG. In each drawing, the symbol "Y" denotes the main scanning direction, the symbol "X" denotes the sub-scanning direction, and the symbol "Z" denotes the vertical direction.

[0016] 1, in an inkjet printing device 1, a carriage 3 is supported by a horizontally arranged guide rail 2. The carriage 3 is provided so as to be movable forward and backward in the longitudinal direction of the guide rail 2 (main scanning direction Y). 2, the carriage 3 is equipped with a plurality of inkjet heads 30 (30a to 30d) and a UV irradiator 32. In the following, when there is no need to distinguish between the inkjet heads 30a to 30d, they are also simply referred to as inkjet heads 30.

[0017] The medium M is positioned below the carriage 3. When printing on the medium M, the carriage 3 moves on the guide rails 2 in the main scanning direction Y. At this time, based on commands from a control device (not shown), ink droplets are ejected from each inkjet head 30 (30a to 30d) onto the surface of the medium M, forming an image on the surface of the medium M. When the ink used for printing is ultraviolet curable ink, the ink droplets that have landed on the medium M are irradiated with ultraviolet light from a UV irradiator 32 to solidify and fix the ink droplets.

[0018] FIG. 3 is a diagram showing a schematic cross section of the inkjet head 30. As shown in FIG. The inkjet head 30 has a nozzle plate 31 at a portion facing the medium M. In the nozzle plate 31, nozzle rows each consisting of a plurality of nozzle holes 31a are arranged in the same direction.

[0019] A head port 35 having an ink supply port 36 is attached to the top of the inkjet head 30. An ink supply pipe 11 extending from the ink tank 10 is connected to the ink supply port 36. The ink supply port 36 is connected to a filter chamber 33. Ink in the ink tank 10 is supplied to the filter chamber 33 via the ink supply port 36.

[0020] The ink supplied to the filter chamber 33 passes through a head filter 34 and is supplied to an ink ejection chamber (not shown). A piezoelectric element is provided in the ink ejection chamber. When the piezoelectric element is driven, the ink in the ink ejection chamber is ejected from the nozzle hole 31a toward the medium M.

[0021] Here, the head filter 34 is provided in a direction along the horizontal line, and ink supplied to the filter chamber 33 passes across the head filter 34 from above to below. The horizontal direction means the horizontal direction based on the installation state of the inkjet printing apparatus 1 relative to the installation surface G (see FIG. 1). Here, the optimum diameter of the mesh (openings) of the head filter 34 to be used varies depending on the type of inkjet head 30. In this embodiment, as an example, a head filter 34 with openings of 5 to 8 μm is used.

[0022] Fine particles such as pigments and resins are dispersed in the ink. As a result, the fine particles in the ink may aggregate and form bridges that cover the mesh of the head filter 34 (a bridging phenomenon). This can cause the aggregated particles to clog the head filter 34.

[0023] In this embodiment, rolling elements (spheres 50) are disposed in the filter chamber 33 in order to prevent clogging of the head filter . Specifically, at least one rolling element (sphere 50) is placed on the head filter 34 that is provided in a horizontal direction. In this embodiment, a sphere 50 having a circular outer shape in a top view is placed on the head filter 34. Here, the "sphere" in this specification only needs to have a degree of circularity that allows it to make point contact with the top surface of the head filter 34. Therefore, the sphere 50 does not need to be a perfect sphere. Therefore, even a sphere having an elliptical outer shape in a top view can be used as long as it can make point contact with the top surface of the head filter 34.

[0024] In this embodiment, when printing on the medium M, the moment (acceleration) when the carriage 3 moves in the main scanning direction Y causes the sphere 50 to roll on the surface of the head filter . In the present invention, it is considered that the rolling balls 50 suppress the occurrence of the bridging phenomenon by producing the following action. (a) The rolling spheres 50 generate convection of ink on the surface of the head filter 34, dispersing particles that have aggregated on the surface of the head filter 34. (b) The rolling spheres 50 move through the particles that have aggregated on the surface of the head filter 34, thereby dispersing the particles that have aggregated on the surface of the head filter 34. (c) The rolling direction of the spheres 50 is not limited to a specific direction, so that the spheres 50 move randomly without being concentrated in a specific area on the top surface of the head filter 34, thereby suppressing the occurrence of the bridging phenomenon over a wide area without being concentrated in a specific area of the head filter 34.

[0025] When the sphere 50 is submerged in the ink passing through the filter chamber 33, a buoyant force acts on the sphere 50. If the buoyant force causes the sphere 50 to separate from the surface of the head filter 34, the sphere 50 will no longer be able to roll on the surface of the head filter 34 during printing, and the above-mentioned actions (a), (b), and (c) may not be exerted. For example, if the spheres are made of resin, they have a low specific gravity, and therefore when submerged in ink, they may float up from the surface of the head filter 34. In addition, the spheres need to have a density that allows them to physically contact the top surface of the head filter 34 and to roll (tumble) on the top surface of the head filter 34 as the inkjet head 30 moves. Therefore, in this embodiment, a sphere made of a non-magnetic metallic material, specifically a sphere made of stainless steel, which has a high specific gravity and excellent durability, is used.

[0026] The spheres 50 are formed with a diameter larger than the mesh (openings) of the head filter 34. In the present embodiment, as an example, spheres with a diameter of 1φ (1 mm) are used. This is because if the diameter of the spheres 50 is smaller than the mesh of the head filter 34, the spheres 50 may get stuck in the mesh of the head filter 34, which may hinder the rolling of the spheres 50.

[0027] Fig. 4 is a diagram illustrating the relationship between the head filter 34 and the sphere 50. Fig. 4(a) is an enlarged schematic diagram showing the filter chamber 33 and its surroundings in the inkjet head 30. Fig. 4(a) corresponds to a cross-sectional view taken along line AA in Fig. 3. Fig. 4(b) is a diagram illustrating the projected area of the sphere 50 relative to the area of the head filter 34. Fig. 4(c) is a diagram illustrating the projected area of the parallel pin 50A relative to the area of the head filter 34. In addition, in (b) and (c) of FIG. 4, the effective rolling range and projected area of the sphere 50 and the parallel pin 50A are indicated by hatching.

[0028] The filter chamber 33 has a substantially rectangular shape in cross section, and the opening on the lower side (the nozzle plate 31 side) of the filter chamber 33 is covered by the head filter 34. The ink supplied to the filter chamber 33 passes through the head filter 34 from above to below and is supplied to the nozzle plate 31 side. The usable area of the head filter 34 is approximately the same as the opening area, in cross section, of the filter chamber 33. The sphere 50 is in point contact with the upper surface of the head filter 34 and has a circular outer shape in top view.

[0029] In the inkjet printing device 1, the inkjet head 30 moves in the main scanning direction Y when printing on the medium M. In this embodiment, the total number and diameter of the spheres 50 arranged in the filter chamber 33 are determined so that the spheres 50 can roll freely within the filter chamber 33 when the inkjet head 30 moves.

[0030] Specifically, the total number and diameter of the spheres are set so that the ratio of the total projected area of each sphere to the area of the head filter 34 (the density of spheres) is 3% or more and 30% or less. Here, if the diameter of each sphere 50 is φ, the projected area R of one sphere 50 is π(φ / 2) 2 Here, the projected area R of the sphere 50 is the hatched circular area in FIG. 4(b) (R=π(φ / 2) 2 ). When the total number of spheres 50 placed on the head filter 34 is N, the projected area R2 of all spheres is N×π(φ / 2) 2 (R2=N×π(φ / 2) 2 ). Then, the ratio of the projected area R2 of the entire sphere to the area R1 of the head filter 34 is R2 / R1=(N×π(φ / 2) 2 ) / R1.

[0031] In this embodiment, the arrangement density (R2 / R1) and diameter φ of the spheres are set so that the ratio of the projected area R2 of all spheres to the area R1 of the head filter 34 satisfies the following relationship, that is, 3% or more and 30% or less. 0.03≦Placement density≦0.3 (1) Therefore, for example, if the area R1 of the head filter 34 is 20 mm 2 When the diameter of the spheres 50 is 1φ (1.0 mm), 1.5φ (1.5 mm), or 2φ (2.0 mm), the projected area and arrangement density of the spheres are as shown in the table below.

[0032] [Table 1]

[0033] Therefore, the total number of spheres N that satisfy the above formula (1) is If spheres of 1φ (1mm) are used, the number will be 1 to 7. If 1.5φ (1.5mm) spheres are used, the number will be one to four. If a 2φ (2mm) sphere is used, the number will be two instead of one.

[0034] If the arrangement density is low, the bridging phenomenon is not sufficiently suppressed, and the possibility that the ink passage through the head filter 34 is obstructed increases. Therefore, the ratio (arrangement density) of the total spherical projected area R2 to the area R1 of the head filter 34 is preferably 3% to 30%, more preferably 5% to 20%, or more preferably 10% to 20%. If the arrangement density exceeds 30%, the resistance increases when ink passes through the head filter 34. If the arrangement density is less than 3%, the bridging phenomenon is not sufficiently suppressed.

[0035] Therefore, when the placement density condition is 5% or more and 20% or less, if the diameter of sphere 50 is 1φ (1 mm), the total number of spheres will be 2 to 5. If the diameter of sphere 50 is 1.5φ (1.5 mm), the total number of spheres will be 1 to 3. If the diameter of sphere 50 is 2φ (2 mm), the total number of spheres will be 1.

[0036] Furthermore, when the placement density condition is 10% or more and 20% or less, when the diameter of sphere 50 is 1φ (1 mm), the total number of spheres is 3 to 5. When the diameter of sphere 50 is 1.5φ (1.5 mm), the total number of spheres is 2 or 3. When the diameter of sphere 50 is 2φ (2 mm), the total number of spheres is 1.

[0037] Here, the degree of clogging of the head filter after passing ink under the following conditions is calculated as follows: (A) A case where rolling elements (spheres 50, parallel pins 50A) are placed on the head filter 34, and (B) a case where the spheres 50 are not placed on the head filter 34 were each examined. The verification conditions and the verification results will be explained below.

[0038] [Verification conditions] <Head filter> A rectangular head filter with an area of 4 mm x 5 mm was used. For the verification, the head filter was placed in a filter chamber with an opening of 4 mm x 5 mm in the pseudo head, and the ink supplied to the filter chamber was made to flow across the filter from top to bottom. In this case, the filter area was 20 mm 2 is. <Rolling elements> (A) Sphere Five stainless steel spheres 50 with a diameter of 1 mm were placed on the head filter 40 in the pseudo-filter chamber (see FIG. 4(b)). In this case, the projected area R of the five spheres relative to the head filter 40 was 3.93 mm 2 is. (B) Parallel pin A parallel pin 50A having a diameter of 2 mm and a length of 4 mm was placed on the head filter 40 in the pseudo-filter chamber (see FIG. 4(c)). In this case, the projected area R' of the parallel pin relative to the head filter 40 was 8.0 mm 2 is. <Test conditions> To simulate the scanning of the carriage (inkjet head) during printing, the pseudo head was moved at a speed of 466 mm / s and an acceleration of 0.43 G, while SP ink was passed through the head filter at a head difference of 50 cm in a room temperature environment.

[0039] The verification results under the above test conditions are shown in Tables 2 and 3 below. The surface images in Table 2 are electron microscope photographs of the surface of the head filter 40 after the test. In the microscope photographs, the fewer the aggregates and foreign matter, the more black they appear, and the aggregates and foreign matter appear white. In the area analysis, the areas where foreign matter is attached are shown in red.

[0040] [Table 2]

[0041] [Table 3]

[0042] When the agitator was not placed on the head filter, the clogging rate of the head filter increased from 50.28% before the test to 76.13%, and the reduction rate of the SP ink flow rate in the head filter was 100%. When a single parallel pin was placed on the head filter as an agitator, the filter clogging rate increased from 50.28% before the test to 64.51%. The flow rate of the SP ink decreased by 36.20%. When five spheres were placed on the head filter as agitators, the filter clogging rate increased from 50.28% before the test to 66.31%. The flow rate of the SP ink decreased by 8.50%.

[0043] From the above, it was confirmed that when the rolling elements were mounted on the head filter, the decrease in ink flow rate after the test was suppressed more than when the rolling elements were not mounted. It was also confirmed that using a sphere as the agitator reduced the decrease in ink flow rate after the test compared to using a parallel pin.

[0044] As shown in FIG. 4(b), the sphere 50 comes into contact (point contact) with the upper surface of the head filter 34 at point C. Therefore, the effective rolling range of the sphere 50 in the head filter 34, which is 4 mm x 5 mm, is a range of 3 mm x 4 mm. 4(c), the parallel pin 50A makes line contact with the top surface of the head filter 34 at line C'. Therefore, the effective rolling range of the parallel pin 50A in the 4 mm x 5 mm head filter 34 is a range of 2 mm x 5 mm. Therefore, as a rolling element, the ball 50 rolls in a wider range than the parallel pin 50A.

[0045] When the rolling elements are disposed in the filter chamber 33 of the inkjet head 30, the rolling elements are introduced through the ink supply port . Here, when the parallel pin 50A is placed on the head filter 34, the parallel pin 50A needs to be arranged so that the longitudinal direction of the parallel pin 50A is perpendicular to the main scanning direction Y. However, when the parallel pin 50A is inserted from the ink supply port 36, the longitudinal direction of the parallel pin 50A is not necessarily perpendicular to the main scanning direction Y.

[0046] In contrast, in the case of the spheres 50, it is not necessary to align the orientation. Therefore, in this embodiment, the balls 50 are used as the rolling elements because of their wide effective rolling range and ease of installation, although this does not exclude the use of parallel pins 50A.

[0047] When multiple spheres 50 are placed on the head filter 34, the movement direction of the spheres 50 is not limited to a specific direction like the parallel pins 50A when the inkjet head 30 moves in the main scanning direction. Therefore, each sphere 50 moves randomly (see FIG. 4(a)). As a result, particles agglomerated on the head filter 34 can be dispersed more reliably by the spheres 50 passing through the area where the particles are agglomerated. This makes it possible to suppress the occurrence of the bridging phenomenon.

[0048] In the above embodiment, the ink passing through the head filter 34 in the filter chamber 33 is ultraviolet-curable ink. Ultraviolet-curable ink has a high tendency to form aggregates. Therefore, by placing multiple spheres on the head filter 34, the possibility of clogging can be reduced in the head filter 34 that uses ultraviolet-curable ink.

[0049] In addition, when the printing apparatus is a modeling apparatus for a three-dimensional structure, it is preferable to apply the present invention to a filter chamber of an inkjet head that ejects support material ink. Here, the support material ink is an ink composition used to form a region that supports a shaped object (support region). An example of a support material ink is disclosed in JP 2018-183890 A. When creating a three-dimensional structure, the amount of support material ink used is greater than the amount of other inks used to form the object. As a result, inkjet heads used for supporting material ink are more susceptible to filter clogging than other inkjet heads. Therefore, by placing a plurality of spheres on the head filter 34 in the inkjet head for the support material ink, the possibility of clogging of the head filter 34 can be reduced.

[0050] In the above embodiment, the total number of spheres to be placed is determined in consideration of the ratio R2 of the total projected area of each sphere 50 to the area R1 of the head filter 34 (see formula (1) above). Here, the total number and diameter φ of the spheres 50 may be set based on the area R1 of the head filter 34.

[0051] For example, the total number of spheres 50 and the diameter φ may be set so that the total projected area R2 of each sphere 50 is 1 / 30 or more and 1 / 3 or less of the area R1 of the head filter 34, satisfying the following relationship. (R1 / 30) ≦ Total projected area of the sphere R2 ≦ (R1 / 3) (2)

[0052] Therefore, for example, if the area R1 of the head filter 34 is 12 mm 2 In this case, the total projected area R2 of the spheres 50 placed on the head filter 34 is 0.4 mm 2 or more, 4mm 2 The total number of spheres and the diameter φ are set so as to satisfy the following relationship:

[0053] Referring to Table 1 above, the total number N of spheres that satisfy the above formula (2) is: If spheres of 1φ (1mm) are used, the number will be 1 to 5. If a 1.5φ (1.5mm) sphere is used, the number will be one to two. If a 2φ (2mm) sphere is used, there will be one.

[0054] In addition, the total number of spheres to be placed on the head filter 34 may be determined taking into consideration the length L (see (b) of Figure 4) of the head filter 34 in a direction perpendicular to the main scanning direction Y of the inkjet head 30 and the diameter φ of the spheres 50.

[0055] For example, as shown in (b) of Figure 4, if the head filter 34 has a length L (5 mm) in a direction perpendicular to the main scanning direction Y and the spheres 50 have a diameter φ (1 mm), at least five spheres 50 (5 ÷ 1 = 5) can be lined up in the direction perpendicular to the main scanning direction Y. 4(a), the spheres 50 move in a random direction when the inkjet head 30 moves, so there is a possibility that the spheres 50 may become biased to one side as the inkjet head 30 repeatedly moves. Therefore, it is preferable to set the total number of spheres 50 so that (i) multiple spheres can be arranged in at least one row on the head filter 34 in a direction perpendicular to the main scanning direction Y, and (ii) the ratio of the total projected area of each sphere to the area of the head filter 34 does not exceed the aforementioned 30%.

[0056] For example, if the total number of spheres 50 with a diameter of 1 mm is seven, conditions (i) and (ii) are satisfied. In this case, even if some of the spheres 50 are unevenly positioned, the two spheres that exceed the five can fill the space created by the uneven positioning. This allows the spheres 50 to roll over a wide range when the inkjet head 30 moves. Furthermore, by satisfying condition (ii), the spheres 50 are less likely to obstruct the flow of ink passing through the head filter 34. In place of the condition (ii), the condition (iii) that the total R2 of the projected areas of the spheres 50 is equal to or less than one-third of the area R1 of the head filter 34 may be adopted.

[0057] As described above, the inkjet printing apparatus 1 having the following configuration has been disclosed in the embodiment. (1) The inkjet printing device 1 includes an inkjet head 30 that moves in the main scanning direction Y during printing, In the inkjet head 30, a filter chamber 33 is provided on a path for supplying ink to the nozzle holes 31a (nozzles); The filter chamber 33 has a sphere 50 placed on a head filter 34 (filter). The sphere 50 has a diameter φ larger than the mesh of the head filter 34 . The spheres 50 are arranged on the head filter 34 so as to be able to roll as the inkjet head 30 moves.

[0058] With this configuration, when the inkjet head 30 is displaced during printing, the spheres 50 placed on the head filter 34 roll on the head filter 34. As a result, the rolling spheres 50 generate ink convection on the surface of the head filter 34, dispersing aggregated particles and suppressing the occurrence of the bridging phenomenon. Furthermore, the rolling spheres 50 come into contact with the aggregates on the surface of the head filter 34 and disperse the aggregates, thereby suppressing the occurrence of the bridging phenomenon.

[0059] (2) The sphere 50 is made of a non-magnetic metal material (stainless steel).

[0060] If the spheres 50 are lightweight, when the spheres 50 are submerged in ink passing through the filter chamber 34, the spheres 50 may be lifted by buoyancy and separated from the head filter 34. This may prevent ink convection from occurring on the surface of the head filter 34, making it impossible to suppress the occurrence of the bridging phenomenon. Therefore, by using spheres 50 made of a non-magnetic metal material, it is possible to prevent the spheres 50 from separating from the surface of the head filter 34 due to buoyancy when the spheres 50 are submerged in ink passing through the filter chamber 33. As a result, the spheres 50 placed on the head filter 34 roll on the head filter 34 during printing, and the rolling spheres 50 generate ink convection on the surface of the head filter 34, thereby suppressing the occurrence of the bridging phenomenon.

[0061] Furthermore, if the spheres are made of resin, they may wear over time as they roll on the top surface of the head filter 34. If the spheres wear out, they may not be able to sufficiently prevent the occurrence of bridging. Furthermore, if the spheres break due to wear, the resulting fragments may become foreign matter and have an undesirable effect on the head filter 34. If the spheres are made of a magnetic material, when the spheres are magnetized, they may gather together due to magnetic force or may become stuck to the wall that forms the filter chamber 34. In such a case, the spheres 50 may no longer roll on the top surface of the head filter 34, which may make it impossible to prevent the occurrence of the bridging phenomenon. As described above, by using a sphere made of stainless steel, it is possible to suitably prevent such a situation from occurring.

[0062] (3) A plurality of spheres 50 are placed on the head filter 34 . The spheres 50 are arranged at a density such that the ratio R2 of the total projected area of the spheres 50 to the area R1 of the head filter 34 is 3% or more and 30% or less.

[0063] If the arrangement density (R2 / R1) of the spheres 50 becomes high, the spheres 50 collide with each other, and the spheres 50 do not roll sufficiently on the head filter 34. This narrows the area in which the spheres 50 roll on the head filter 34, making it difficult to generate sufficient ink convection on the surface of the head filter 34. Furthermore, if the arrangement density (R2 / R1) of the spheres 50 becomes high, the spheres 50 will act as a resistance to the flow of ink passing through the head filter 34, and the flow rate of ink passing through the head filter 34 will decrease. Furthermore, if the arrangement density of the spheres 50 is low, the area in the head filter 34 in which the spheres 50 actually roll will be narrower, making it difficult to generate sufficient ink convection on the surface of the head filter 34. By setting the arrangement density of the spheres 50 within the above range, the convection required to disperse the agglomerates can be generated on the surface of the head filter 34. This makes it possible to suppress the occurrence of the bridging phenomenon.

[0064] (4) A plurality of spheres 50 are placed on the head filter 34 . The total number and diameter of the spheres 50 are set so that the total projected area R2 of the spheres 50 relative to the area of the head filter is 1 / 3 to 1 / 30 of the area R1 of the head filter .

[0065] With this configuration, the convection required to disperse the aggregates can be generated on the surface of the head filter 34. Therefore, the occurrence of the bridging phenomenon can be suppressed.

[0066] (5) The ink is an ultraviolet curing ink.

[0067] UV-curable inks are prone to forming aggregates, so applying this ink to an inkjet printing device that uses UV-curable inks can help prevent the occurrence of bridging.

[0068] (6) The ink is a support material ink used in three-dimensional modeling.

[0069] The support material used in 3D modeling is large in volume, which tends to cause nozzle clogging, so applying this technology to inkjet printing devices used in 3D modeling can help prevent the occurrence of bridging.

[0070] The present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the technical concept of the present invention. [Explanation of symbols]

[0071] 1. Inkjet printing device 30(30a~30d) Inkjet head 32 UV irradiator 33 Filter chamber 34 Head filter 35 Head Port 36 Ink supply port 50 spheres (rolling bodies) 50A Parallel pin (rolling element) M Media X main scanning direction

Claims

1. an inkjet head that moves in a scanning direction during printing; a filter chamber provided on a path for supplying ink to the nozzles in the inkjet head; a rolling element mounted on the filter in the filter chamber, the rolling elements have a diameter larger than the mesh of the filter; the rolling elements are arranged so as to be capable of rolling and moving randomly on the surface of the filter as the inkjet head moves, An inkjet printing device in which the rolling elements move randomly on the surface of the filter to disperse particles that have aggregated on the surface of the filter.

2. The inkjet printing apparatus according to claim 1 , wherein the rolling elements are spheres made of a non-magnetic metallic material.

3. A plurality of the spheres are placed on the filter, 3. The inkjet printing apparatus according to claim 2, wherein a ratio of a projected area of the sphere to an area of the filter is equal to or greater than 3% and equal to or less than 30%.

4. A plurality of the spheres are placed on the filter, 3. The inkjet printing apparatus according to claim 2, wherein the total projected area of the spheres relative to the filter is 1 / 3 to 1 / 30 of the area of the filter.

5. The inkjet printing apparatus according to claim 1 , wherein the ink is an ultraviolet curable ink.

6. The inkjet printing apparatus according to claim 1 , wherein the ink is a support material ink used in three-dimensional modeling.

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