JP6376123B2 - Inkjet printing method - Google Patents

Description

  The present invention relates to an inkjet printing method, and more particularly to an inkjet printing method for inkjet printing on a three-dimensional object.

  In recent years, attempts have been made to use the ink jet printing method in various technical fields.

  In the inkjet printing method, printing is usually performed in a state where the image recording surface of a recording medium such as paper is arranged in parallel to the nozzle surface of the inkjet head. However, in Patent Document 1, printing is performed on a curved body. Has been proposed.

  Patent Document 1 discloses that when a colored liquid is applied to a contact lens by an ink jet method, a dot is arranged in a square lattice shape to prevent a problem that a diffraction image is formed on the retina. It is described that, when a plurality of ink droplets to be applied are applied to a curved body, the ejection state such as the landing position and the droplet size is intentionally made non-uniform (randomized). This prevents dots from being arranged in a square lattice and prevents uneven ink density.

  However, since this technique uses non-uniformity (randomization), there is inevitably a problem that it is difficult to obtain the accuracy of the coating edge portion. Further, as will be described later, there is room for improvement in the prevention of uneven ink density.

Japanese Patent Laid-Open No. 2005-40652

  When inkjet printing is performed on a three-dimensional object under the same drawing conditions in the main scanning direction or sub-scanning direction, the larger the slope or curved surface slope, the smaller the number of dots (dot drawing density) applied per unit area. .

  As a result, for example, when a coating film is formed by printing, a desired film thickness cannot be obtained on slopes or curved surfaces, or the film thickness is uneven between slopes with different slopes or between different parts within a curved surface. It becomes.

  In particular, when the coating film to be formed is a functional film such as a light-shielding film or a conductive film, there is a concern that it may affect optical characteristics and conductive performance.

  Moreover, when the inventor has tested, the coating film applied to the three-dimensional object tends to increase stress on a three-dimensional surface with a large difference in inclination angle, and the film thickness is particularly uneven in such a part. It was found that the film was easily peeled off.

  As in the technique described in Patent Document 1, it is not possible to sufficiently prevent the deviation due to the slope or the curved surface as described above by simply making the discharge state non-uniform (randomized).

  The inventor diligently studied, and by performing printing under specific conditions according to the inclination of the slope or curved surface, when performing inkjet printing on a three-dimensional object, the density of ink dots can be made uniform and a desired density can be imparted. In particular, it was found that the film thickness can be made uniform, a desired film thickness can be imparted, and the adhesion can be further improved during the formation of the coating film.

  Therefore, the object of the present invention is to make the density of ink dots uniform when ink-jet printing on a three-dimensional object, particularly to uniform the film thickness when forming a coating film, and to further improve the adhesion of the coating film to the three-dimensional object. Another object of the present invention is to provide an ink jet printing method and a three-dimensional object printed by the method.

  Another problem of the present invention is that when ink jet printing is performed on a three-dimensional object, the density of ink dots can be set to a desired density, and in particular, the film thickness can be set to a desired film thickness when forming a coating film. Another object of the present invention is to provide an ink jet printing method and a three-dimensional object printed by the method.

  Still other problems of the present invention will become apparent from the following description.

    The above problems are solved by the following inventions.

1.
In the ink jet printing method of inkjet printing on three-dimensional object, according to the inclination angle of the swash surface having the stereo object, in the ink-jet printing method of printing by changing the number of ejection frequency of the ink droplets ejected from the nozzle provided in the inkjet head There,
The three-dimensional object has a tilt angle theta _X are different from each other two or more surfaces against the nozzle surface in the cross section and along the main scanning direction perpendicular to the nozzle surface of the inkjet head at least,
When printing over the two or more surfaces, an angle perpendicular to the nozzle surface is a flying angle α of the ink droplet with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the main scanning direction. The ejection frequency ν in the main scanning direction is “ν × (cos θ _X + [sin θ _X / tan α]) = ν ₀ ” (where ν ₀ is printed on a surface parallel to the nozzle surface. Ink jet printing method in which the ejection frequency is changed by changing the time interval of the ejection signal for ejecting ink from the nozzle according to the tilt angle so as to satisfy the condition of the ejection frequency in the case .
2.
In the ink jet printing method of inkjet printing on three-dimensional object, according to the inclination angle of the swash surface having the stereo object, an inkjet printing method for printing by changing the number of nozzles for ejecting ink droplets among the plurality of nozzles provided in an inkjet head Because
The three-dimensional object, the inclination angle theta _Y has at least a two or more different surfaces to each other with respect to the nozzle surface in a cross section taken along and the sub-scanning direction perpendicular to the nozzle surface of the inkjet head,
When printing over the two or more surfaces, the number n of nozzles ejected in the sub-scanning direction is “n × cos θ _Y = n ₀ ” (where n ₀ is a surface parallel to the nozzle surface) The number of nozzles to be ejected is changed by changing the number of nozzles that input ejection signals for ejecting ink from the nozzles according to the inclination angle so as to satisfy the condition of is allowed, the inkjet printing method number of ink dots to be applied per unit area is Ichika equalizing prevented from becoming sparse than desired density.
3.
In an inkjet printing method for inkjet printing on a three-dimensional object, both the ejection frequency of the ink droplets ejected from the nozzles provided in the inkjet head and the number of nozzles to be ejected are changed according to the inclination angle of the inclined surface of the three-dimensional object. An inkjet printing method for printing,
The three-dimensional object, the inclination angle theta _X are different from each other face against the nozzle surface in a cross section taken along and the main scanning direction perpendicular to the nozzle surface of the inkjet head, and the sub-scanning direction perpendicular to the nozzle surface of the inkjet head And having at least two or more surfaces including surfaces having different inclination angles θ _Y with respect to the nozzle surface in a cross section along
When printing over the two or more surfaces, an angle perpendicular to the nozzle surface is a flying angle α of the ink droplet with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the main scanning direction. The ejection frequency ν in the main scanning direction is “ν × (cos θ _X + [sin θ _X / tan α]) = ν ₀ ” (where ν ₀ is printed on a surface parallel to the nozzle surface. The ejection frequency is changed by changing the time interval of ejection signals for ejecting ink from the nozzles according to the inclination angle so as to satisfy the condition of the ejection frequency in the case. number of nozzles n for discharging in the direction "n × cos [theta] _Y = n _0" (where, n ₀ is the number of nozzles for ejecting the case of printing on a plane parallel to the nozzle surface.) So as to satisfy the condition, according to the inclination angle, by changing the number of nozzles for inputting the ejection signal for ejecting ink from the nozzle, by changing the number of nozzles for ejecting ink applied to a unit area dot prevention to equalizing Ichika be Louis inkjet printing method that the number is sparse than desired density.
4).
In an inkjet printing method for inkjet printing on a three-dimensional object, the inkjet printing method performs printing by changing the ejection frequency of the ink droplets ejected from the nozzles of the inkjet head according to the inclination angle of the curved surface of the three-dimensional object. ,
Approximating the curved surface to a plurality of inclined surfaces including at least surfaces having different inclination angles θ _XC with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the main scanning direction ;
When printing over the plurality of inclined surfaces, the flying angle α of the ink droplet with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the main scanning direction is different from the angle perpendicular to the nozzle surface. and values, ejection frequency [nu is in the main scanning direction, "ν × (cosθ _XC + [sin [theta _XC / tan [alpha]) = [nu _0" (where, [nu _0, when printing on a plane parallel to the nozzle surface Ink jet printing method in which the ejection frequency is changed by changing the time interval of ejection signals for ejecting ink from the nozzles in accordance with the inclination angle so as to satisfy the condition of the ejection frequency.
5.
In an inkjet printing method for inkjet printing on a three-dimensional object, an inkjet printing method for printing by changing the number of nozzles that eject ink droplets among a plurality of nozzles provided in an inkjet head according to the inclination angle of the curved surface of the three-dimensional object There,
Approximating the curved surface to a plurality of inclined surfaces including at least surfaces having different inclination angles θ _YC with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the sub-scanning direction ;
When printing over the plurality of inclined surfaces, the number n of nozzles ejected in the sub-scanning direction is “n × cos θ _YC = n ₀ ” (where n ₀ is the case where printing is performed on a surface parallel to the nozzle surface) The number of nozzles to be ejected is changed by changing the number of nozzles for inputting ejection signals for ejecting ink from the nozzles according to the inclination angle so as to satisfy the condition of the number of nozzles to be ejected). An inkjet printing method for preventing the number of ink dots applied per unit area from becoming sparser than a desired density and making it uniform.
6).
In an inkjet printing method for inkjet printing on a three-dimensional object, both the ejection frequency of the ink droplets ejected from the nozzles of the inkjet head and the number of nozzles to be ejected are changed according to the inclination angle of the curved surface of the three-dimensional object. An inkjet printing method for printing,
The curved surface is perpendicular to the nozzle surface of the inkjet head and has a different inclination angle θ _XC with respect to the nozzle surface in a section along the main scanning direction, and perpendicular to the nozzle surface of the inkjet head and along the sub-scanning direction. Approximating a plurality of slopes including at least surfaces having different inclination angles θ _YC with respect to the nozzle surface in a cross section ,
When printing over the plurality of inclined surfaces, the flying angle α of the ink droplet with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the main scanning direction is different from the angle perpendicular to the nozzle surface. and values, ejection frequency [nu is in the main scanning direction, "ν × (cosθ _XC + [sin [theta _XC / tan [alpha]) = [nu _0" (where, [nu _0, when printing on a plane parallel to the nozzle surface The ejection frequency is changed and the sub-scanning direction is changed by changing the time interval of the ejection signal for ejecting ink from the nozzle according to the inclination angle so as to satisfy the condition of number of nozzles n for discharging in the "n × cos [theta] _YC = _{n 0"} (where, _{n 0} is the number of nozzles for ejecting the case of printing on a plane parallel to the nozzle surface.) So as to satisfy the condition, according to the inclination angle, by changing the number of nozzles for inputting the ejection signal for ejecting ink from the nozzle, by changing the number of nozzles for ejecting ink applied to a unit area dot inkjet printing method Ichika equalizing to prevent that the number is sparse than desired density.
7).
In an inkjet printing method for performing inkjet printing on a three-dimensional object, the inkjet printing method performs printing by determining the ejection frequency ν of ink droplets ejected from the nozzles of the inkjet head according to the inclination angle of the inclined surface of the three-dimensional object. And
The inclined surface is inclined at an inclination angle θ _X with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the main scanning direction,
When printing on the inclined surface, the flying angle α of the ink droplet with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the main scanning direction is different from the angle perpendicular to the nozzle surface. The discharge frequency ν is “ν = ν ₀ / (cos θ _X + [sin θ _X / tan α])” (where ν ₀ is the discharge frequency when printing on a surface parallel to the nozzle surface. The inkjet printing method for determining the time interval of the ejection signal for ejecting the ink from the nozzle so as to satisfy the condition (1).
8).
In an inkjet printing method for inkjet printing on a three-dimensional object, an inkjet printing method for printing by determining the number n of nozzles that eject ink droplets among a plurality of nozzles provided in an inkjet head according to the inclination angle of the slope of the three-dimensional object Because
The inclined surface is inclined at an inclination angle θ _Y with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the sub-scanning direction,
When printing on the inclined surface, the number n of nozzles to be discharged is “n = n ₀ / cos θ _Y ” (where n ₀ is the number of nozzles to be discharged when printing on a plane parallel to the nozzle surface. .) conditions to determine the number of nozzles for inputting the ejection signal for ejecting ink from the nozzles in Suyo meet the, number of ink dots to be applied per unit area prevented from becoming sparse than desired density inkjet printing method Ichika equalizing with.
9.
The inkjet printing method according to any one of 1 to 8 , wherein the three-dimensional object is any one selected from a cover case for an electronic terminal, a golf ball, a keyboard, a display member for an electronic terminal, an LED, an OLED, and an optical member.

Main part schematic plan view showing an example of the basic configuration of an inkjet printing apparatus The figure explaining an example of the inkjet printing method (the principal part schematic plan view of an inkjet printing apparatus) III-III sectional view in FIG. IV-IV sectional view in FIG. The figure explaining the other example of the inkjet printing method (the principal part schematic plan view of an inkjet printing apparatus) VI-VI line sectional view in FIG. VII-VII line sectional view in FIG. The figure explaining an example of the aspect using a derivative function The figure explaining the other example of the aspect using a derivative function The figure explaining the further another example of the inkjet printing method The figure explaining the 1st aspect of the setting method of the number n of nozzles to discharge The figure explaining the 2nd aspect of the setting method of the number n of nozzles to discharge. The figure explaining the 3rd aspect of the setting method of the number n of nozzles to discharge The figure explaining an Example The figure explaining an Example

  The inkjet printing method according to the present invention is suitably used when inkjet printing is performed on a three-dimensional object.

  The three-dimensional object is an inclined surface in which at least a part or all of a surface to be printed by ink jet printing (surface to which ink is applied) is inclined with respect to the nozzle surface of the ink jet head, or the nozzle surface of the ink jet head. An object composed of an inclined curved surface.

  In one aspect, when inkjet printing is performed on a three-dimensional object, the ejection frequency of the ink droplets ejected from the nozzles of the inkjet head and the number of nozzles ejected according to the inclination angle of the inclined surface or curved surface of the three-dimensional object Either or both of them are changed. Thereby, the density of the ink provided to the three-dimensional object can be made uniform as a whole, and the film thickness can be made uniform particularly in the formation of a coating film. Furthermore, the adhesion of the coating film to the three-dimensional object can be improved.

  In another aspect, when performing inkjet printing on a three-dimensional object, either or both of the ejection frequency ν of the ink droplets ejected from the nozzles included in the inkjet head and the number of nozzles n to be ejected are set in the three-dimensional object. It is determined according to the slope angle of the slope. As a result, ink can be applied at a desired density to the slope or curved surface of a three-dimensional object, and in particular, a desired film thickness can be applied in the formation of a coating film.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a main part schematic plan view showing an example of a basic configuration of an ink jet printing apparatus.

  In FIG. 1, an inkjet printing apparatus H includes a transport stage 3 for placing a three-dimensional object 1 to be printed so as to be transportable in the sub-scanning direction (upward in the figure), and a plurality of inks that eject ink toward the three-dimensional object 1. And an inkjet head 2 having a nozzle 22 on a nozzle surface 21.

  As an ejection method of the inkjet head, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electro-thermal conversion method (for example, Examples thereof include a thermal ink jet type, a bubble jet (registered trademark) type, an electrostatic attraction type (for example, an electric field control type, a slit jet type, etc.) and a discharge type (for example, a spark jet type). The electro-mechanical conversion method is preferable, but any discharge method may be used.

  The ink jet head 2 is mounted on the carriage 20 in such a manner that it can reciprocate in a main scanning direction (a direction perpendicular to the sub-scanning direction) along a guide member (not shown) during image formation. Driven in the main scanning direction by driving (shown).

  At the time of image recording, the nozzle surface 21 on which the nozzles 22 of the inkjet head 2 are formed is disposed so as to face the printing surface 11 of the three-dimensional object 1 conveyed on the conveyance stage 3.

  The ink jet head 2 is operated by an ejection unit (not shown) provided therein with ink supplied by an ink supply unit (not shown) during scanning moving in the main scanning direction by driving the head scanning unit. Thus, the number of nozzles 22 used for ejection (the number of nozzles to be ejected) n and the ejection frequency ν from each nozzle 22 are appropriately changed to be ejected and landed on the printing surface 11 of the three-dimensional object 1.

  The above-described scanning in the main scanning direction is performed as many times as necessary, and after ejecting ink toward one landable area, the three-dimensional object 1 is appropriately moved in the sub-scanning direction together with the transport stage 3, and then the head scanning means again. While performing the scanning in the main scanning direction of the inkjet head 2, the ink is ejected to the next landable area adjacent to the landable area.

  The above operation is repeated, and the printing surface 11 is printed for each area of the printing surface 11 of the solid object 1 in conjunction with the relative movement between the solid object 1 and the inkjet head 2 in the main scanning direction and the sub-scanning direction. Printing is performed by ejecting ink while appropriately changing at least one or both of the ejection frequency ν and the number of nozzles n to be ejected according to the inclination angle of the slope or curved surface of the ink.

  Hereinafter, a method of changing at least one or both of the ejection frequency ν and the number of nozzles n to be ejected according to the inclination angle will be described with a specific example.

  FIG. 2 is a diagram for explaining an example of the ink jet printing method and is a schematic plan view of a main part of the ink jet printing apparatus. 3 is a sectional view taken along line III-III in FIG. 2, and FIG. 4 is a sectional view taken along line IV-IV in FIG.

  2 to 4, 1 is a three-dimensional object, and 2 is an inkjet head.

  The inkjet head 2 has a plurality of nozzles 22 on the nozzle surface 21. The plurality of nozzles 22 are arranged at predetermined intervals along the sub-scanning direction.

  The three-dimensional object 1 has a printing surface 11 that is an object to be printed by the inkjet head 2.

  The printing surface 11 includes a surface S0 (hereinafter sometimes referred to as a parallel surface) S0 disposed in parallel to the nozzle surface 21 of the inkjet head 2 (hereinafter sometimes referred to as a parallel surface) S1 and a surface S1 disposed in an inclined state. To S4.

As shown in FIG. 3, the surface S <b _{> 1 is at} an angle of θ _X1 with respect to the nozzle surface 21 in a cross section perpendicular to the nozzle surface 21 and along the main scanning direction (hereinafter sometimes referred to as a main scanning direction cross section). Inclined. Further, the surface S2 is inclined at an angle of −θ _X2 with respect to the nozzle surface 21 in the cross section in the main scanning direction.

  In the process of moving along the main scanning direction, the ink jet head 2 ejects ink from the nozzles 22 provided on the nozzle surface 21 at predetermined time intervals, and performs printing by landing on the printing surface 11. .

Usually, the number of ink ejections per unit time (hereinafter sometimes referred to as ejection frequency) ν in one nozzle 22 is a constant value ν ₀ that can apply ink at a desired density in the main scanning direction to the parallel plane S0. In this state, printing is performed on the entire printing surface 11. However, as shown, if the printing surface 11 has a surface S1, S2 arranged in a state of being inclined with respect to the nozzle surface 21 in the main scanning direction cross section, printing the ejection frequency as a constant value [nu ₀ As a result, ink is applied to the surfaces S1 and S2 at a density different from the desired density (usually sparser than the desired density). As a result, printing accuracy is impaired. In particular, when a coating film is formed by combining a plurality of ink dots applied from the inkjet head 2 on the surfaces S11 and S12, the number of ink dots applied per unit area differs from a desired value. As a result, it becomes difficult to impart a desired film thickness to the coating film, and it becomes difficult to make the film thickness uniform with other surfaces.

When the printing surface 11 includes a plurality of surfaces S0, S1, and S2 having different inclination angles in the cross section in the main scanning direction, the ejection frequencies ν ₀ , ν _1, and ν for these surfaces S0, S1, and S2 are used. ₂ is preferably printed so as to satisfy the following conditions.

ν ₀ × cos θ _X0 = ν ₁ × cos θ _X1 = ν ₂ × cos−θ _X2

Since cos (−θ) = cos θ, the inclination angle can be converted into an absolute value and v ₂ × cos−θ _X2 = ν ₂ × cos θ _X2 .

Further, if the above formula is generalized, printing is performed so that the ejection frequency ν in the main scanning direction satisfies the following condition on a plurality of surfaces (at least two or more) having different inclination angles θ _X in the main scanning direction section. It is preferable to carry out.

ν × cos θ _X = constant (1)

  As a result, the ink can be applied at a uniform density over the entire surfaces S0, S1, and S2 having different inclination angles in the cross section in the main scanning direction, and the effect of improving printing accuracy can be obtained. In addition, since the number of ink dots applied per unit area can be set to the same value throughout, an effect of promoting uniform film thickness can be obtained particularly in coating film formation.

Also, when printing to the inclined angle θ surface S1 arranged in inclined state at _X, S2 the nozzle surface 21 in the main scanning cross section, the ejection frequency ν in the main scanning direction, the following conditions It is preferable to perform printing so as to satisfy the above.

ν = ν ₀ / cos θ _X (2)

Here, as described above, ν ₀ is a value (a constant value) set when ink is applied at a desired density in the main scanning direction with respect to the parallel plane S0.

That is, printing is performed with the setting of the ejection frequency ν ₁ = ν ₀ / cos θ _{X1 on} the surface S1, and the ejection frequency of the ejection frequency ν ₂ = ν ₀ / cos (−θ _X2 ) with respect to the surface S2. It is preferable to perform printing. Since cos (−θ) = cos θ, the inclination angle may be converted into an absolute value, and the discharge frequency ν ₂ = ν ₀ / cos θ _X2 may be set.

By satisfying the above conditions, the main scanning direction surface S1 arranged in a state of being inclined at an inclination angle theta _X relative to the nozzle surface 21 in the cross section, S2, will be able to impart ink in a desired density Thus, the effect of improving the printing accuracy can be obtained. Moreover, since the number of ink dots provided per unit area can be set to a desired value, an effect of easily providing a desired film thickness can be obtained particularly in coating film formation.

  In the above description, the correspondence to the inclination in the cross section in the main scanning direction has been described. Next, the correspondence to the inclination in the cross section in the sub scanning direction will be described.

As shown in FIG. 4, in the printing surface 11, the surface S <b> 3 is perpendicular to the nozzle surface 21 and is a section along the sub-scanning direction (hereinafter sometimes referred to as a sub-scanning direction section) with respect to the nozzle surface 21. And inclined at an angle of θ _Y1 . In addition, the surface S4 is inclined at an angle of −θ _Y2 with respect to the nozzle surface 21 in the cross section in the sub-scanning direction.

  After being moved to a predetermined position in the sub-scanning direction, the inkjet head 2 ejects ink using only a predetermined number n of selected nozzles 22 among the plurality of nozzles 22 provided on the nozzle surface 21. This is landed on the printing surface 11 and printing is performed.

Usually, the number of selected nozzles 22 (hereinafter sometimes referred to as the number of ejected nozzles) n is set to a constant value n ₀ that can apply ink at a desired density in the sub-scanning direction with respect to the parallel plane S0. In this state, printing is performed on the entire printing surface 11. However, as shown in the figure, when the printing surface 11 has surfaces S3 and S4 arranged in a state inclined with respect to the nozzle surface 21 in the cross section in the sub-scanning direction, the number of nozzles to be ejected is set to a constant value n _0. When printing is performed, the ink is applied to the surfaces S3 and S4 at a density different from the desired density (usually sparser than the desired density). As a result, printing accuracy is impaired. In particular, on the surfaces S3 and S4, when a coating film is formed by combining a plurality of ink dots applied from the inkjet head 2, the number of ink dots applied per unit area differs from a desired value. As a result, it becomes difficult to impart a desired film thickness to the coating film, and it becomes difficult to make the film thickness uniform with other surfaces.

When the printing surface 11 is composed of a plurality of surfaces S0, S3, and S4 having different inclination angles in the cross section in the main scanning direction, the number of nozzles n ₀ , n ₁ to be ejected to each of these surfaces S0, S3, and S4. And n ₂ are preferably printed so that the following conditions are satisfied.

_{n 0 × cosθ Y0 = n 1} × cosθ Y1 = n 2 × cosθ Y2

Since cos (−θ) = cos θ, the inclination angle can be converted into an absolute value and can be set to n ₂ × cos−θ _Y2 = n ₂ × cos θ _Y2 .

Also, if generalizing the above equation, the plane of the plurality of inclination angle theta _Y in the sub scanning cross section are different from each other (at least two), the number of nozzles n for discharging in the sub-scanning direction, the following condition is satisfied It is preferable to perform printing.

n × cos θ _Y = constant (3)

  As a result, ink can be applied at a uniform density over the entire surfaces S0, S3 and S4 having different inclination angles in the sub-scanning direction cross section, and the effect of improving printing accuracy can be obtained. In addition, since the number of ink dots applied per unit area can be set to the same value throughout, an effect of promoting uniform film thickness can be obtained particularly in coating film formation.

  Surprisingly, a uniform coating thickness can be achieved over a plurality of surfaces having different inclination angles in the main scanning direction cross-section or sub-scanning direction cross-section as described above. The effect which can improve the adhesiveness with respect to a thing is also acquired.

Also, when printing to the inclined angle θ plane S3, which is disposed in an inclined state with _Y, S4 with respect to the nozzle surface 21 in the sub-scanning cross section, the number of nozzles n for discharging in the sub-scanning direction, It is preferable to perform printing so as to satisfy the following conditions.

n = n ₀ / cos θ _Y (4)

Here, n ₀ is a value (a constant value) set when ink is applied at a desired density in the sub-scanning direction with respect to the parallel plane S ₀ as described above.

That is, printing is performed on the surface S3 with the setting of the number of ejected nozzles n ₁ = n ₀ / cos θ _Y1 , and on the surface S4, the number of ejected nozzles n ₂ = n ₀ / cos (−θ _Y2). It is preferable to perform printing at an ejection frequency of Since cos (−θ) = cos θ, the inclination angle may be converted into an absolute value, and the condition of the number of nozzles to be discharged n ₂ = n ₀ / cos θ _Y2 may be used.

By satisfying the above conditions, the inclined angle θ plane S3, which is disposed in an inclined state with _Y, S4 with respect to the nozzle surface 21 in the sub-scanning cross section, will be able to impart ink in a desired density Thus, the effect of improving the printing accuracy can be obtained. Moreover, since the number of ink dots provided per unit area can be set to a desired value, an effect of easily providing a desired film thickness can be obtained particularly in coating film formation.

  In the above description, the conditions for dealing with the inclination in the cross section in the main scanning direction and the conditions for dealing with the inclination in the cross section in the sub-scanning direction are individually described. However, it is preferable to perform printing in combination of these. It is.

  Since the ejection frequency ν and the number of nozzles n to be ejected can be set independently of each other, the above-described ejection frequency ν can be applied to the slope having both the inclination in the main scanning direction section and the inclination in the main scanning direction section. And the condition of the number of nozzles to be ejected n can be applied simultaneously for printing.

More specifically, printing surface 11, at least chromatic and the inclination angle theta _X is different surfaces in the main scanning cross section, two or more surfaces comprising an inclined angle theta _Y is different surfaces in the sub scanning cross section In particular, at least one of these surfaces preferably has both a slope in the cross section in the main scanning direction and a slope in the cross section in the main scanning direction.

When printing over these two or more surfaces, the ejection frequency ν in the main scanning direction satisfies the condition “ν × cos θ _X = constant”, and the number of nozzles n ejected in the sub-scanning direction is “n × cos θ _Y It is preferable to change the discharge frequency and the number of nozzles to be discharged in accordance with the inclination angle so that the condition “= constant” is satisfied.

  In the above description, the case where the printing surface 11 of the three-dimensional object 1 includes an inclined surface that is inclined with respect to the nozzle surface 21 has been described, but the present invention is also preferably applied when the printing surface 11 includes at least a curved surface. . Below, the aspect in case the to-be-printed surface 11 contains a curved surface is demonstrated in detail.

  FIG. 5 is a diagram for explaining another example of the ink jet printing method, and is a schematic plan view of a main part of the ink jet printing apparatus. 6 is a sectional view taken along line VI-VI in FIG. 5, and FIG. 7 is a sectional view taken along line VII-VII in FIG.

  That is, the cross-sectional view shown in FIG. 6 corresponds to a cross-sectional view cut along a cross section (main cross section in the main scanning direction) perpendicular to the nozzle surface 21 of the inkjet head 2 and along the main scanning direction. This corresponds to a cross-sectional view taken along a cross section (sub-scan direction cross section) perpendicular to the nozzle surface 21 of the inkjet head 2 and along the sub-scan direction.

  As shown in FIGS. 5 to 7, the printing surface 11 of the three-dimensional object 1 includes a parallel surface S0 parallel to the nozzle surface 21 and a curved surface S5. Here, the surface shape of the curved surface S5 is a concave curved surface shape corresponding to a part of the inner surface of the sphere.

  When printing on the curved surface S5, first, the curved surface S5 is considered as an aggregate of minute surfaces ΔS. That is, the curved surface cannot have a constant inclination angle as a whole surface, but the inclination angle (tangential angle) of each minute surface ΔS approximates a specific value by finely dividing the surface into minute surfaces ΔS. In addition, since it is converged, it can be handled in the same manner as an inclined surface having a certain inclination angle.

  The dividing method into the minute surface ΔS is not particularly limited. For example, as shown in FIG. 5, it is preferable to divide the curved surface S5 so as to have a lattice shape when viewed from the direction perpendicular to the nozzle surface 21. . In the example shown in the figure, this lattice is formed by intersecting straight lines along the main scanning direction and the sub-scanning direction at predetermined intervals. The predetermined interval can be appropriately determined depending on, for example, the size of the curved surface S5. Specifically, the predetermined interval is preferably in the range of 10 μm to 1000 μm, more preferably in the range of 50 μm to 200 μm, and 80 μm to 120 μm. Most preferably, it is in the range.

Here, paying attention to the cross section in the main scanning direction of FIG. 6, the minute surface ΔS is inclined at the inclination angle θ _XC in the cross section in the main scanning direction.

On the other hand, paying attention to the cross section in the sub-scanning direction in FIG. 7, the minute surface ΔS is inclined at an inclination angle θ _YC in the cross section in the sub-scanning direction.

  Therefore, by dividing the curved surface S5 into the minute surface ΔS, the conditions described in FIGS. 1 to 3 (Equation (1) to Equation (4)) can be suitably applied.

When printing on the curved surface S5, the ejection condition in the main scanning direction is adjusted so that the ejection frequency ν satisfies the condition of “ν × cos θ _XC = constant” according to the inclination angle θ _XC of the minute surface ΔS. Furthermore, it is preferable to adjust the ejection conditions in the sub-scanning direction so that the number n of nozzles ejected satisfies the condition “n × cos θ _YC = constant” according to the inclination angle θ _YC of the minute surface ΔS.

  Thereby, even when printing on a curved surface, the film thickness can be made uniform over the entire curved surface. Furthermore, the effect which can improve the adhesiveness with respect to the solid thing of the formed coating film by this is also acquired.

Further, when printing on the curved surface S5, the ejection frequency ν is “ν = ν ₀ / cos θ _XC ” (where ν ₀ is the time when ink is applied at a desired density in the main scanning direction with respect to the parallel surface S0. And the number of ejected nozzles is “n = n ₀ / cos θ _YC ” (where n ₀ is in the sub-scanning direction with respect to the parallel plane S 0). (It is a value set when ink is applied at a desired density.) It is preferable to satisfy the condition of), whereby a desired film thickness can be more suitably applied.

  In the above description, the curved surface S5 is a concave curved surface, but the shape of the curved surface is not limited to this. For example, it is also preferable to apply to a convex curved surface.

  As described above, in describing printing on a curved surface, an aspect in which the printing surface 11 is divided into minute surfaces ΔS has been described. However, as a further aspect, an aspect using a derivative will be described.

That is, the line shape of the printing surface 11 (which may include either a slope or a curved surface) in the cross section in the main scanning direction is made to correspond to the function y _X = f (x _X ) (FIG. 8). The inclination angle θ _{X in the} cross section in the main scanning direction at an arbitrary position x _X in the main scanning direction coordinates can be expressed as follows.

cos θ _X = 1 / (1+ [f ′ (x _X )] ² ) ^1/2 ... Formula (5)

Here, f ′ (x _X ) is a derivative obtained by differentiating f (x _X ) once with respect to x _X.

The equation (5), corresponding to an arbitrary position x _X in the main scanning direction coordinate of the printing surface 11, ejection frequency ν is, it is preferable to carry out printing on the following condition is satisfied.

ν = ν ₀ × (1+ [f ′ (x)] ² ) ^1/2 ... formula (1a)

Note that the expression (1a) corresponds to the value obtained by substituting the value of cos θ _X in the expression (5) into the above-described expression (1), thereby obtaining the effect described for the condition of the expression (1).

In addition, it is preferable to perform printing so that the ejection frequency ν satisfies the following condition corresponding to each position x _X in the main scanning direction coordinates of the printing surface 11.

ν / (1+ [f ′ (x _X )] ² ) ^1/2 = constant Equation (2a)

Note that the expression (2a) corresponds to the value obtained by substituting the value of cos θ _X in the expression (5) into the above-described expression (2), thereby obtaining the effect described for the condition of the expression (2).

Similarly, the surface 11 to be printed is made to correspond to the function y _Y = f (x _Y ) in the sub-scanning direction cross section of the surface 11 to be printed (which may include a slope or a curved surface) (FIG. 9). The inclination angle θ _{Y in the} cross section in the sub-scanning direction at an arbitrary position x _Y in the sub-scanning direction coordinates can be expressed as follows.

cos θ _Y = 1 / (1+ [f ′ (x _Y )] ² ) ^1/2 ... (6)

Here, f ′ (x _Y ) is a derivative obtained by differentiating f (x _Y ) once with respect to x _Y.

Corresponding to each position x _Y in the sub-scanning direction coordinate of the printing surface 11, the nozzle number n to discharge, it is preferable to perform printing on the following condition is satisfied.

n / (1+ [f ′ (x _Y )] ² ) ^1/2 = constant ... Formula (3a)

Note that the expression (3a) corresponds to the value obtained by substituting the value of cos θ _Y in the expression (6) into the above-described expression (3), and thereby the effect described for the condition of the expression (3) is obtained.

Further, in response to an arbitrary position x _Y in the sub-scanning direction coordinate of the printing surface 11, the nozzle number n to discharge, it is preferable to perform printing on the following condition is satisfied.

n = n ₀ × (1+ [f ′ (x _Y )] ² ) ^1/2 ... formula (4a)

Note that the expression (4a) corresponds to the value obtained by substituting the value of cos θ _Y in the expression (6) into the above-described expression (4), and thereby the effect described for the condition of the expression (4) is obtained.

  As described above, by carrying out based on the derivative, it becomes easy to print while continuously changing the discharge conditions.

The method of making the cross-sectional line shape of the slope or curved surface correspond to the function y _X = f (x _X ) or the function y _Y = f (x _Y ) is not particularly limited, and approximates or corresponds to this based on the measured value. Preferred examples include a method using a function to perform, a method of extracting based on a design such as a design drawing of a three-dimensional object, and the like.

  FIG. 10 is a diagram for explaining still another example of the ink jet printing method, and is a schematic cross-sectional view of a main part cut along a cross section perpendicular to the nozzle surface 21 of the ink jet head 2 and along the main scanning direction. The three-dimensional object 1 shown in FIG. 10 has the same configuration as that shown in FIGS.

  Ink droplets ejected from the nozzles 22 of the nozzle surface 21 of the inkjet head 2 can normally be handled as those ejected in a direction perpendicular to the nozzle surface 21. However, more strictly, it is preferable to consider the influence of the moving speed of the inkjet head 2 in the main scanning direction. As the moving speed of the inkjet head 2 increases with respect to the flying speed of the ink droplets, the flying direction of the ink droplets may deviate from the direction perpendicular to the nozzle surface 21 in some cases.

  In the example of FIG. 10, the ink droplet flying angle α is different from the angle perpendicular to the nozzle surface 21 (α = 90 °) (specifically α <90 °) in the cross section in the main scanning direction. Have taken.

  As described above, even when the flying angle α of the ink droplet is α <90 °, when printing is performed on the parallel surface S0 parallel to the nozzle surface 21, ink is applied at a desired density. obtain.

  However, when the flying angle α of the ink droplet is α <90 °, the slopes S1 and S2 (or the minute surface ΔS in the case of a curved surface) constituting the printing surface 11 of the three-dimensional object 1 are used. When printing is performed, ink can be applied at a density different from the desired density in the main scanning direction. This is a complex phenomenon caused by the inclination angle θ of the slopes S1 and S2 and the ink flying angle α.

  The following mode is particularly suitable in such a case, and ink can be applied at a further uniform density, and ink can be applied at a desired density with higher accuracy.

First, with respect to the main scanning direction inclined in cross-sectional angle theta _X are different from each other more surfaces S0, S1 and S2 (at least two) (which may be a small surface ΔS described above), the ejection frequency ν is the following It is preferable to perform printing so as to satisfy the conditions.

ν × (cos θ _X + [sin θ _X / tan α]) = constant Equation (7)

  This allows ink to be applied at a more uniform density across multiple surfaces.

Also, when printing in the main scanning direction surface S1 arranged in a state of being inclined at an inclination angle theta _X relative to the nozzle surface 21 in a cross section, S2 (or may be a small surface ΔS as described above) In addition, it is preferable to perform printing so that the discharge frequency ν satisfies the following conditions.

ν = ν ₀ / (cos θ _X + [sin θ _X / tan α]) (8)

Here, as described above, ν ₀ is a value (a constant value) set when ink is applied at a desired density in the main scanning direction with respect to the parallel plane S0.

  This makes it possible to apply ink with a desired density to the slope or curved surface with higher accuracy.

In the equations (7) and (8), the value of tan α may be derived from the measured value of the flying angle α of the ink droplet, or the velocity V of the ink droplet in the vertical direction with respect to the nozzle surface 21. _i a may be used as a value obtained by dividing the main scanning direction velocity V _h of the speed of movement of the inkjet head 2.

In this aspect, in the expressions (7) and (8), by substituting the values of the following expressions (5) and (9) as cos θ _X and sin θ _X , an aspect using the above-described derivative is obtained. Combinations are also possible.

cos θ _X = 1 / (1+ [f ′ (x _X )] ² ) ^1/2 ... Formula (5)

sin θ _X = f ′ (x _X ) / (1+ [f ′ (x _X )] ² ) ^1/2 ... Expression (9)

  The adjustment method of the discharge frequency ν and the number of nozzles n to be discharged is not particularly limited. For example, the inkjet printing apparatus includes a control unit (not shown) configured to change or determine the discharge frequency ν and the number of nozzles n to be discharged based on the above-described conditions. The control unit can control the ejection frequency ν by setting the time interval of ejection signals (signals for ejecting ink from the nozzles 22) input to the ejection means based on the conditions. Further, the control unit thins out a predetermined number of nozzles out of all usable nozzles in the inkjet head 2 based on conditions (the number of nozzles to be discharged is not input to the predetermined number of nozzles). n can be controlled.

  The adjustment of the number n of nozzles ejected in the inkjet head 2 will be described in more detail below.

  FIG. 11 is a diagram for explaining a first aspect of the method for setting the number n of nozzles to be ejected, and shows a state in which the inkjet head 2 is viewed in plan.

  In FIG. 11, the inkjet head 2 has four nozzles 21 arranged in parallel in the sub-scanning direction on the nozzle surface 21. Note that the number of nozzles 21 arranged in parallel is usually larger, for example, on the order of several tens to several thousand, but here, for convenience, four cases will be described as an example.

When the illustrated inkjet head 2 is used to print the same region of the printing surface 11 in one pass (one scan in the main scanning direction of the inkjet head 2), the total number n _max of selectable nozzles 22 is This corresponds to the total number of nozzles included in the inkjet head 2, and is 4 in the illustrated example. Therefore, the number n of nozzles to be ejected can be selected within a range of 4 or less by making any nozzle 22 a non-ejection nozzle.

  FIG. 12 is a diagram for explaining a second mode of the method for setting the number n of nozzles to be ejected, and shows a state in which the inkjet head is viewed in plan.

  In the example of FIG. 12, four inkjet heads 2 are mounted on one head unit 20.

  The four nozzles 21 provided in each inkjet head 2 are arranged so as to be shifted from each other so as to fill the space between the nozzles provided in the other inkjet heads 2.

When printing the same region of the printing surface 11 in one pass using the head unit 20 shown in the figure, the total number n _max of selectable nozzles 22 corresponds to the total number of nozzles included in the plurality of inkjet heads 2. In the example shown, it is 16. Therefore, the number n of nozzles to be ejected can be selected within a range of 16 or less by making any nozzle 22 a non-ejection nozzle.

  FIG. 13 is a diagram for explaining a third aspect of the method for setting the number n of nozzles to be ejected, and shows a state in which the inkjet head is viewed in plan.

  In the example of FIG. 13, using the inkjet head 2, printing is performed by an interleave method in which printing is performed in a plurality of passes on the same region of the printing surface 11.

  The interleaving method is a method in which printing is performed in a plurality of passes while shifting the inkjet head in the sub-scanning direction so as to fill the space between the nozzles in the previous pass.

As shown in the figure, if printing is performed in four passes by the interleave method, the total number n _max of selectable nozzles 21 is 16 (the product of the total number of nozzles 4 provided in the inkjet head 2 and the number of passes 4). Therefore, the number n of nozzles to be ejected can be selected within a range of 16 or less by making any nozzle 21 a non-ejection nozzle.

  The number of paths in the interleave method is not particularly limited, but is preferably in the range of 4 to 12 paths, for example.

  As described above, the number n of nozzles to be ejected can be determined based on a predetermined condition (formula), but when the value of n derived from the formula is not an integer, for example, rounding off or decimal place is used. It can be determined as an integer by rounding it down.

In the above description, the values of the inclination angles θ _X and θ _Y may be acquired by measuring the inclined surface or curved surface, or may be acquired based on the design of the design of the three-dimensional object 1, for example. Good.

  In the above description, the case where the printing surface 11 has two or more surfaces with different inclination angles has been described, but the present invention is not limited to this. For example, even if the printing surface 11 is a single flat surface as a whole, if the flat surface is arranged so as to be inclined with respect to the nozzle surface during printing, it can be a three-dimensional object. By suitably applying the present invention, for example, it is possible to obtain an effect that ink dots can be applied so as to have a desired density (or film thickness).

  The inkjet printing method is preferably used particularly when an ink coating is formed on the printing surface 11 of the three-dimensional object 1. The coating film refers to a film in which a plurality of ink dots applied to the printing surface 11 are united on the surface to reach a two-dimensional spread.

  The coating film to be formed is formed continuously over two or more surfaces having different inclination angles on the printing surface 11 from the viewpoint of remarkably exhibiting the effects of the present invention, particularly the adhesion effect. Is preferred.

  The ink used is not particularly limited, but it is a photo-curing type that is cured by irradiation with active energy rays such as ultraviolet rays, electron beams, X-rays, radiation, and high frequencies from the viewpoint of adaptability to coating film formation. In particular, it is preferable to use a cationic photopolymerizable ink.

  The irradiation with the active energy ray is performed after the photocationic polymerization ink is applied to the printing surface 11. The timing of irradiation may be applied every time each ink droplet is applied, or may be irradiated every two or more ink droplets or after all the ink droplets are applied.

  The use of the inkjet printing method is not particularly limited, but for example, decoration of a cover case of an electronic terminal for a smartphone, marking on a golf ball, printing on a personal computer keyboard, to a display member such as a 3D-shaped smartphone cover glass It is particularly preferably used for printing light shielding window frames, printing conductive films on three-dimensional devices such as LEDs and OLEDs, printing functional films such as semiconductor films (so-called printed electronics field), and forming light shielding films for optical members such as lenses. be able to.

  Examples of the present invention will be described below, but the present invention is not limited to such examples.

(Test 1)
As shown in FIG. 14, the printing area 11 is parallel to the nozzle surface 21 of the inkjet head 2 (θ _X0 = 0 °) and 45 ° with respect to the nozzle surface 21 in the cross section in the main scanning direction. A three-dimensional object 1 constituted by a surface S6 inclined at an inclination angle (θ _X6 = 45 °) was prepared.

  The scanning method was an interleaved method, and printing was performed on the entire surface 11 to be printed using the inkjet head 2 in 8 passes.

<Printing conditions>
When printing over the surface S0 and the surface S6, “ν ₀ × cos θ _X0 = ν ₆ × cos θ _X6 = constant” was set based on the condition of the expression (1).

The ejection frequency ν ₀ in the main scanning direction when printing on the surface S0 was set so that the film thickness on the surface S0 was 13 μm.

The ejection frequency ν ₆ in the main scanning direction when printing on the surface S6 was set to “ν ₆ = ν ₀ / cos θ _X6 ” based on the condition of the equation (2) described above.

(Test 2)
In Test 1, printing was performed in the same manner as in Test 1 except that the printing conditions were as follows.

<Printing conditions>
The discharge frequency ν _{0 was} constant over the entire surface S0 and surface S6.

(Test 3)
As shown in FIG. 15, the printing area 11 is parallel to the nozzle surface 21 (θ _Y0 = 0 °) of the inkjet head 2 and 45 ° with respect to the nozzle surface 21 in the sub-scanning direction cross section. A three-dimensional object 1 constituted by a surface S7 inclined at an inclination angle (θ _Y7 = 45 °) was prepared.

  The scanning method was an interleaved method, and printing was performed on the entire surface 11 to be printed using the inkjet head 2 in 8 passes.

<Printing conditions>
When printing over the surface S0 and the surface S7, “n ₀ × cos θ _y0 = n ₇ × cos θ _y7 = constant” was set based on the condition of the expression (3).

Number of nozzles n ₀ for discharging in the sub-scanning direction when printing the surface S0, the film thickness at said surface S0 is set to be 13 .mu.m.

Number of nozzles _{n 7} which discharges in the sub-scanning direction when printing the surface S7, based on the condition of the above equation (4), is set to _"n 7 _{= n} 0 / _{cosθ y7".}

(Test 4)
In Test 3, printing was performed in the same manner as in Test 1 except that the printing conditions were as follows.

<Printing conditions>
And a nozzle number n ₀ of constant discharge throughout the surface S0 and the surface S7.

(Test 5)
A three-dimensional object 1 similar to that shown in FIGS. That is, the printing surface 11 of the three-dimensional object 1 includes a surface S0 that is parallel to the nozzle surface 21 and a curved surface S5 that is a hemispherical concave curved surface.

  The scanning method was an interleaved method, and printing was performed on the entire surface 11 to be printed using the inkjet head 2 in 8 passes.

<Printing conditions>
The ejection frequency ν ₀ when printing on the surface S0 and the number of nozzles n ₀ ejected were set such that the film thickness on the surface S0 was 13 μm.

  When printing on the curved surface S5, first, the curved surface S5 is partitioned by a grid formed by intersecting straight lines along the main scanning direction and the sub-scanning direction at intervals of 100 μm, so that a plurality of inclination angles are approximated. A minute surface ΔS was defined.

Small surface ΔS are each has a tilt angle theta _X in the main scanning cross section and an inclined angle theta _Y in the sub-scanning cross section.

  Printing is performed so that the ejection frequency ν in the main scanning direction and the number n of nozzles ejected in the sub scanning direction satisfy the conditions of the following formulas (1) and (3) on the plurality of minute surfaces ΔS. went.

ν × cos θ _X = constant (1)

n × cos θ _Y = constant (3)

At this time, the ejection frequency ν and the number of nozzles n to be ejected when printing on the minute surface ΔS are expressed by the following formula (2) between the ejection frequency ν ₀ and the number of nozzles n ₀ to be ejected when printing on the surface S0. ) And (4).

ν = ν ₀ / cos θ _X (2)

n = n ₀ / cos θ _Y (4)

(Test 6)
In Test 5, printing was performed in the same manner as in Test 5 except that the printing conditions were as follows.

<Printing conditions>
A constant discharge frequency ν ₀ and the number of nozzles to be discharged n ₀ were set over the entire surface S0 and surface S5.

  About the three-dimensional object with a coating film obtained by Tests 1-6, it evaluated by the following evaluation method.

<Evaluation method>
-Adhesiveness The following evaluation criteria evaluated the adhesiveness of the coating film with respect to a solid thing.

(Evaluation criteria)
○: Stored for 2 months in an environment of a temperature of 85 ° C. and a relative humidity of 90%, and there is no change in appearance such as peeling or cracking of the coating film.
X: Changes in appearance such as peeling or cracking of the coating film are observed by storage under the same conditions as above.

-Film thickness difference About the formed coating film, the film thickness difference of the film thickness in the part on a parallel surface (S0) and the film thickness in the part on a slope or a curved surface was computed. In addition, the film thickness in the part on a parallel surface (S0) was 13 micrometers in any test.

  In the case of Test 6, since there was a variation in the film thickness within the curved surface S5, the film thickness difference from the film thickness in the portion on the parallel plane (S0) was calculated after taking the average.

  The above evaluation results are shown in Table 1.

＜評価＞

<Evaluation>

  From Table 1, in tests 1, 3 and 5 using the ink jet printing method according to the present invention, compared with tests 2, 4 and 6 which are comparative examples, the film thickness uniformity is excellent over surfaces having different inclination angles. I understand that. Furthermore, in comparison with tests 2, 4 and 6 which are comparative examples, a desired film thickness (a film thickness equivalent to a coating film formed on the reference parallel surface S0) is imparted to the slope and the curved surface. I understand that I can do it.

1: Solid object 11: Printed surface S1 to S7: Surface (which constitutes the printed surface) H: Inkjet printing device 2: Inkjet head 21: Nozzle surface 22: Nozzle 20: Carriage 3: Conveyance stage

Claims (9)

In the ink jet printing method of inkjet printing on three-dimensional object, according to the inclination angle of the swash surface having the stereo object, in the ink-jet printing method of printing by changing the number of ejection frequency of the ink droplets ejected from the nozzle provided in the inkjet head There,
The three-dimensional object has a tilt angle theta _X are different from each other two or more surfaces against the nozzle surface in the cross section and along the main scanning direction perpendicular to the nozzle surface of the inkjet head at least,
When printing over the two or more surfaces, an angle perpendicular to the nozzle surface is a flying angle α of the ink droplet with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the main scanning direction. The ejection frequency ν in the main scanning direction is “ν × (cos θ _X + [sin θ _X / tan α]) = ν ₀ ” (where ν ₀ is printed on a surface parallel to the nozzle surface. Ink jet printing method in which the ejection frequency is changed by changing the time interval of the ejection signal for ejecting ink from the nozzle according to the tilt angle so as to satisfy the condition of the ejection frequency in the case . In the ink jet printing method of inkjet printing on three-dimensional object, according to the inclination angle of the swash surface having the stereo object, an inkjet printing method for printing by changing the number of nozzles for ejecting ink droplets among the plurality of nozzles provided in an inkjet head Because
The three-dimensional object, the inclination angle theta _Y has at least a two or more different surfaces to each other with respect to the nozzle surface in a cross section taken along and the sub-scanning direction perpendicular to the nozzle surface of the inkjet head,
When printing over the two or more surfaces, the number n of nozzles ejected in the sub-scanning direction is “n × cos θ _Y = n ₀ ” (where n ₀ is a surface parallel to the nozzle surface) The number of nozzles to be ejected is changed by changing the number of nozzles that input ejection signals for ejecting ink from the nozzles according to the inclination angle so as to satisfy the condition of is allowed, the inkjet printing method number of ink dots to be applied per unit area is Ichika equalizing prevented from becoming sparse than desired density. In an inkjet printing method for inkjet printing on a three-dimensional object, both the ejection frequency of the ink droplets ejected from the nozzles provided in the inkjet head and the number of nozzles to be ejected are changed according to the inclination angle of the inclined surface of the three-dimensional object. An inkjet printing method for printing,
The three-dimensional object, the inclination angle theta _X are different from each other face against the nozzle surface in a cross section taken along and the main scanning direction perpendicular to the nozzle surface of the inkjet head, and the sub-scanning direction perpendicular to the nozzle surface of the inkjet head And having at least two or more surfaces including surfaces having different inclination angles θ _Y with respect to the nozzle surface in a cross section along
When printing over the two or more surfaces, an angle perpendicular to the nozzle surface is a flying angle α of the ink droplet with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the main scanning direction. The ejection frequency ν in the main scanning direction is “ν × (cos θ _X + [sin θ _X / tan α]) = ν ₀ ” (where ν ₀ is printed on a surface parallel to the nozzle surface. The ejection frequency is changed by changing the time interval of ejection signals for ejecting ink from the nozzles according to the inclination angle so as to satisfy the condition of the ejection frequency in the case. number of nozzles n for discharging in the direction "n × cos [theta] _Y = n _0" (where, n ₀ is the number of nozzles for ejecting the case of printing on a plane parallel to the nozzle surface.) So as to satisfy the condition, according to the inclination angle, by changing the number of nozzles for inputting the ejection signal for ejecting ink from the nozzle, by changing the number of nozzles for ejecting ink applied to a unit area dot prevention to equalizing Ichika be Louis inkjet printing method that the number is sparse than desired density. In an inkjet printing method for inkjet printing on a three-dimensional object, the inkjet printing method performs printing by changing the ejection frequency of the ink droplets ejected from the nozzles of the inkjet head according to the inclination angle of the curved surface of the three-dimensional object. ,
The curved surface has an inclination angle θ with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the main scanning direction. _XC Approximating a plurality of slopes including at least different surfaces,
When printing over the plurality of inclined surfaces, the flying angle α of the ink droplet with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the main scanning direction is different from the angle perpendicular to the nozzle surface. The ejection frequency ν in the main scanning direction is “ν × (cos θ _XC + [Sin θ _XC / Tanα]) = ν ₀ (However, ν ₀ Is the ejection frequency when printing on a surface parallel to the nozzle surface. The ink jet printing method for changing the ejection frequency by changing the time interval of the ejection signal for ejecting the ink from the nozzle according to the inclination angle so as to satisfy the condition. In an inkjet printing method for inkjet printing on a three-dimensional object, an inkjet printing method for printing by changing the number of nozzles that eject ink droplets among a plurality of nozzles provided in an inkjet head according to the inclination angle of the curved surface of the three-dimensional object There,
The curved surface has an inclination angle θ with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the sub-scanning direction. _YC Approximating a plurality of slopes including at least different surfaces,
When printing over the plurality of inclined surfaces, the number n of nozzles ejected in the sub-scanning direction is “n × cos θ. _YC = N ₀ (However, n ₀ Is the number of nozzles ejected when printing on a surface parallel to the nozzle surface. The number of nozzles to be ejected is changed by changing the number of nozzles for inputting ejection signals for ejecting ink from the nozzles according to the inclination angle so as to satisfy the condition of), and the unit is given per unit area. An ink-jet printing method that prevents the number of ink dots from becoming sparser than a desired density and makes it uniform. In an inkjet printing method for inkjet printing on a three-dimensional object, both the ejection frequency of the ink droplets ejected from the nozzles of the inkjet head and the number of nozzles to be ejected are changed according to the inclination angle of the curved surface of the three-dimensional object. An inkjet printing method for printing,
The curved surface is perpendicular to the nozzle surface of the inkjet head and has a different inclination angle θ _XC with respect to the nozzle surface in a section along the main scanning direction, and perpendicular to the nozzle surface of the inkjet head and along the sub-scanning direction. Approximating a plurality of slopes including at least surfaces having different inclination angles θ _YC with respect to the nozzle surface in a cross section ,
When printing over the plurality of inclined surfaces, the flying angle α of the ink droplet with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the main scanning direction is different from the angle perpendicular to the nozzle surface. and values, ejection frequency [nu is in the main scanning direction, "ν × (cosθ _XC + [sin [theta _XC / tan [alpha]) = [nu _0" (where, [nu _0, when printing on a plane parallel to the nozzle surface The ejection frequency is changed and the sub-scanning direction is changed by changing the time interval of the ejection signal for ejecting ink from the nozzle according to the inclination angle so as to satisfy the condition of number of nozzles n for discharging in the "n × cos [theta] _YC = _{n 0"} (where, _{n 0} is the number of nozzles for ejecting the case of printing on a plane parallel to the nozzle surface.) So as to satisfy the condition, according to the inclination angle, by changing the number of nozzles for inputting the ejection signal for ejecting ink from the nozzle, by changing the number of nozzles for ejecting ink applied to a unit area dot inkjet printing method Ichika equalizing to prevent that the number is sparse than desired density. In an inkjet printing method for performing inkjet printing on a three-dimensional object, the inkjet printing method performs printing by determining the ejection frequency ν of ink droplets ejected from the nozzles of the inkjet head according to the inclination angle of the inclined surface of the three-dimensional object. And
The inclined surface is inclined at an inclination angle θ _X with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the main scanning direction,
When printing on the inclined surface, the flying angle α of the ink droplet with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the main scanning direction is different from the angle perpendicular to the nozzle surface. The discharge frequency ν is “ν = ν ₀ / (cos θ _X + [sin θ _X / tan α])” (where ν ₀ is the discharge frequency when printing on a surface parallel to the nozzle surface. The inkjet printing method for determining the time interval of the ejection signal for ejecting the ink from the nozzle so as to satisfy the condition (1). In an inkjet printing method for inkjet printing on a three-dimensional object, an inkjet printing method for printing by determining the number n of nozzles that eject ink droplets among a plurality of nozzles provided in an inkjet head according to the inclination angle of the slope of the three-dimensional object Because
The inclined surface is inclined at an inclination angle θ _Y with respect to the nozzle surface in a cross section perpendicular to the nozzle surface of the inkjet head and along the sub-scanning direction,
When printing on the inclined surface, the number n of nozzles to be discharged is “n = n ₀ / cos θ _Y ” (where n ₀ is the number of nozzles to be discharged when printing on a plane parallel to the nozzle surface. .) conditions to determine the number of nozzles for inputting the ejection signal for ejecting ink from the nozzles in Suyo meet the, number of ink dots to be applied per unit area prevented from becoming sparse than desired density inkjet printing method Ichika equalizing with. The inkjet printing method according to any one of claims 1 to 8 , wherein the three-dimensional object is any one selected from a cover case for an electronic terminal, a golf ball, a keyboard, a display member for an electronic terminal, an LED, an OLED, and an optical member. .

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