JP6160411B2 - Liquid ejector - Google Patents

Description

  The present invention relates to a liquid ejecting apparatus that ejects a photocurable liquid onto a medium and cures the liquid ejected onto the medium by irradiating the medium with light.

  Conventionally, as a kind of liquid ejecting apparatus, an ink jet printer that prints an image or the like on the medium by ejecting ink from a nozzle formed in the liquid ejecting head to a medium such as a sheet to be conveyed is known. Yes. Some of these printers perform printing by ejecting UV curable ink that is cured by irradiating ultraviolet rays (hereinafter also referred to as “UV”) from nozzles of a liquid ejecting head.

  Here, the UV curable ink spreads on the medium as time passes from the time it is ejected to the medium until it is cured by being irradiated with UV, so that its dot diameter (dot form) changes. For this reason, in a printer including a plurality of liquid ejecting heads, when there are a liquid ejecting head having a long distance to the irradiation unit for irradiating UV and a liquid ejecting head having a short distance, the difference is caused by the difference in distance. In each liquid ejecting head, the time from when the ink is ejected to when the ink is irradiated with UV may be uneven. In such a case, the ink ejected from each liquid ejecting head is irradiated with UV, and the dot diameter when the ink is cured on the medium becomes non-uniform, so that uniform image quality can be obtained on the medium. become unable.

  Therefore, in the printer described in Patent Document 1, the ink ejection amount at the nozzle of the liquid ejection head having a long distance from the irradiation unit is smaller than the ink ejection amount at the nozzle of the liquid ejection head having a short distance from the irradiation unit. doing. For this reason, the dot diameter of a relatively small amount of ink ejected from a nozzle having a long distance from the irradiation unit is still small when it reaches the medium, but increases in the meantime because the time until UV irradiation is long. On the other hand, the dot diameter of a relatively large amount of ink ejected from a nozzle having a short distance from the irradiation unit is already large after landing on the medium, but does not increase in the meantime because the time until UV irradiation is short. In this way, the dot diameter of the ink ejected from the nozzle of the liquid ejecting head having a long distance from the irradiation unit and the nozzle of the liquid ejecting head having a short distance from the irradiation unit is made uniform.

JP 2007-90642 A

  By the way, in the printer as described above, the conveyance speed of the medium may be changed depending on whether the image quality is given priority or the printing speed is given priority. In this case, depending on the conveyance speed of such a medium, the time until the liquid sprayed from the nozzle with a short distance from the irradiation unit is irradiated with UV and the nozzle with a long distance from the irradiation unit was sprayed. The time until the liquid is irradiated with UV changes. For this reason, when the conveyance speed of the medium is changed, in order to make the dot diameter of the ink ejected from the nozzle having a short distance from the irradiation unit and the nozzle having a long distance from the irradiation unit uniform, It is necessary to change the ink ejection amount at the nozzles.

  Here, the amount of ink ejected from the nozzles of the liquid ejecting head can generally be changed in several predetermined stages. For this reason, there is a possibility that an appropriate ink ejection amount cannot be selected when the ink ejection amount is changed according to the conveyance speed of the medium. For example, when the amount of ink ejected by the liquid ejecting head can be changed in three stages (small, medium, and large), there are three combinations with different ink ejecting amounts. There is a possibility that the injection amount cannot be selected. In this case, since an appropriate ink ejection amount cannot be selected, the dot form of the ink when the ejected ink is cured becomes non-uniform. That is, it is difficult to obtain a uniform image quality on the medium, and there is a problem that print quality is deteriorated.

  By the way, when the injection amount other than a predetermined number of steps is required, the injection amount of the steps may be combined to obtain the required injection amount, but the combination is still limited. The above problem still exists.

  Such a situation is not limited to ink jet printers that perform printing using UV curable ink, but is generally common in liquid ejecting apparatuses that eject light curable liquid.

  The present invention has been made in view of these problems. The purpose is to use a liquid ejecting apparatus that includes a plurality of liquid ejecting heads that eject light-curable liquid onto a medium, and the distance from the irradiation unit that irradiates light onto the liquid ejected onto the medium is different for each liquid ejecting head. However, an object of the present invention is to provide a liquid ejecting apparatus that can suppress the non-uniform dot form of the liquid when the liquid is cured on the medium.

  A liquid ejecting apparatus that solves the above-described problems is a first ejecting unit and a second ejecting unit that eject a photo-curable liquid onto a medium, and the liquid ejected from the first ejecting unit at a first irradiation intensity. A liquid ejecting unit having a second irradiating unit capable of irradiating the liquid ejected from the first irradiating unit and the second ejecting unit with a second irradiating intensity, and the first irradiating intensity and the second irradiating unit A control unit that controls irradiation intensity; and a relative movement unit that moves at least one of the medium and the liquid ejecting unit in a first direction and relatively moves the medium and the liquid ejecting unit relative to each other, and In the second direction orthogonal to the first direction, the first injection unit and the second injection unit are arranged at different positions, and the first irradiation unit and the second irradiation unit are arranged at different positions. In the first direction, the first illumination The distance from the first ejection unit to the first ejection unit is shorter than the distance from the second irradiation unit to the second ejection unit, and the control unit moves the set medium and the liquid ejection unit relative to each other. The intensity difference between the first irradiation intensity and the second irradiation intensity is changed according to the set relative movement speed.

  According to the above configuration, the first ejecting unit and the second ejecting unit eject liquid onto the medium while the medium and the liquid ejecting unit are relatively moved by the relative moving unit. Then, in order to prevent the liquid ejected on the medium from gradually spreading on the medium, the first irradiation unit and the second irradiation unit irradiate the liquid ejected on the medium with light. In this way, the liquid sprayed onto the medium is hardened and the liquid is prevented from spreading on the medium, or the speed at which the liquid spreads on the medium is reduced. In addition, when the irradiation intensity is high and when the irradiation intensity is high, the speed at which the liquid spreads after the light irradiation is slower when the irradiation intensity is high.

  Here, in the first direction which is the moving direction of the medium or the moving direction of the liquid ejecting unit, the distance from the first irradiating unit to the first ejecting unit is larger than the distance from the second irradiating unit to the second ejecting unit. It is getting shorter. For this reason, when the medium and the liquid ejecting unit move relative to each other, the time from when the first ejecting unit ejects the liquid onto the medium until the first irradiating unit irradiates the liquid with the second ejecting unit This is shorter than the time from when the liquid is ejected to the medium until the second irradiation unit irradiates the liquid with the light. That is, there is a time difference from when the first irradiation unit irradiates the liquid ejected by the first ejection unit to when the second irradiation unit irradiates the liquid ejected by the second ejection unit. For this reason, an intensity difference is provided so that the second irradiation intensity is higher than the first irradiation intensity in order to suppress a change in the dot form (for example, dot area) of the liquid ejected onto the medium due to such a time difference. It is done.

  The time difference is shortened when the set relative movement speed is fast, and is long when the set relative movement speed is slow. For this reason, when the set relative movement speed changes, the time difference changes, so the intensity difference of the irradiation intensity suitable for the same time difference also changes. Therefore, in the above configuration, by changing the intensity difference according to the set relative movement speed, that is, according to the time difference, it is possible to suppress the nonuniformity of the dot form of the liquid cured on the medium. .

In the liquid ejecting apparatus, it is preferable that the control unit reduce the intensity difference when the set relative movement speed is fast than when the set relative movement speed is slow.
When the set relative movement speed is high, the first injection unit irradiates the liquid ejected by the first injection unit and then the second injection unit injects the liquid, compared to when the set relative movement speed is low. The time until the second irradiation unit irradiates the liquid with the light is shortened. As this time becomes shorter, the dot form of the same liquid when the first irradiation unit irradiates the liquid ejected by the first ejection unit and the second irradiation unit irradiates the liquid ejected by the second ejection unit. The difference with the dot form of the same liquid tends to be small. Therefore, in the above configuration, when the set relative movement speed is high, the intensity difference is made smaller than when the set relative movement speed is low, for example, compared with the case where a constant intensity difference is used regardless of the set relative movement speed. Thus, it is possible to suppress the non-uniform dot form of the liquid cured on the medium.

  In the liquid ejecting apparatus, the liquid ejecting apparatus further includes a storage unit that stores a curing characteristic of the liquid indicating a change in a dot area with respect to time of the liquid ejected onto the medium, and the control unit is based on the curing characteristic. , Calculating the increment of the dot area of the liquid with respect to the passage of time from the timing at which the first irradiation unit irradiates light to the liquid to the timing at which the second irradiation unit irradiates light to the liquid, When the increment is small, it is desirable to make the intensity difference smaller than when the dot area increment is large.

  The curing characteristics of the liquid vary depending on the liquid type and the medium type. According to the above configuration, first, the curing characteristics of such different liquids are obtained from experiments and stored in the storage unit. When the dot area increment calculated based on the curing characteristics is small, the intensity difference is made smaller than when the dot area increment is large, for example, constant regardless of the liquid type or medium type. As compared with the case where the intensity difference is used, it is possible to prevent the dot form of the liquid cured on the medium from becoming non-uniform.

  In the liquid ejecting apparatus, as viewed from the first direction, the first ejecting unit and the first irradiation unit are disposed so as to overlap with each other, and the second ejecting unit and the second irradiation unit are disposed to overlap with each other. It is desirable to be arranged.

  According to the above configuration, in the second direction, the first injection unit and the second injection unit are arranged at different positions, and the first irradiation unit and the second irradiation unit are arranged at different positions. Furthermore, it is arrange | positioned so that a 1st injection part and a 1st irradiation part may overlap as seen from a 1st direction, and a 2nd injection part and a 2nd irradiation part overlap. For this reason, suppressing that the 2nd irradiation part irradiates light to the liquid which the 1st injection part injected while suppressing that the 1st irradiation part irradiates light to the liquid which the 2nd injection part injected. Can do.

  The liquid ejecting apparatus may further include a measuring unit that measures an actual relative moving speed between the medium and the liquid ejecting unit, and the control unit is configured so that the actual relative moving speed is slower than the set relative moving speed. It is desirable to decrease the first irradiation intensity and the second irradiation intensity.

  If the actual relative movement speed may be slower than the set relative movement speed, the irradiation time of the light on the ink on the medium in such a case will be the same as that on the medium when the actual relative movement speed is equal to the set relative movement speed. It becomes longer than the light irradiation time for the ink. Here, when the light irradiation time is long, the cured state of the liquid is further advanced as compared with the case where the light irradiation time is short. For this reason, when the actual relative movement speed is slower than the set relative movement speed, there is a possibility that the liquid is hardened on the medium. Therefore, in the above configuration, the actual irradiation speed becomes slower than the set relative movement speed, so that the first irradiation intensity and the second irradiation intensity are weakened when the light irradiation time becomes longer. According to this, in the case where the actual relative movement speed is the set relative movement speed and in the case where the actual relative movement speed is slower than the set relative movement speed, the dot form of the liquid cured on the medium becomes non-uniform. This can be suppressed.

  The liquid ejecting apparatus may further include an acquisition unit that acquires the type of the medium, and the control unit may change the intensity difference according to the type of the medium acquired by the acquisition unit.

  The curing characteristics of the liquid may change not only when the type of liquid is different, but also when the type of medium is different, for example, when the properties of the surface on which the liquid is ejected or the absorption characteristics of the liquid are different. . In the above configuration, since the strength difference is changed according to the type of the medium, even when the curing characteristic of the liquid is changed by changing the type of the medium, the dot form of the liquid cured on the medium is changed. It is possible to suppress non-uniformity.

FIG. 2 is a perspective view illustrating a schematic configuration of a printer. FIG. 3 is a top view illustrating a schematic configuration of a carriage, in which illustration of a part of the configuration is omitted. FIG. 3 is a block diagram illustrating an electrical configuration of the printer. It is a timing chart explaining the hardening characteristic of ink, (a) is a figure showing change of dot area when irradiation intensity is different, (b) is a figure showing change of dot area when irradiation timing is different, ( (c) is a figure which shows transition of a dot area in case irradiation intensity and irradiation timing differ. A table that determines the supply current for the irradiator. A map that is referenced when determining the gain according to the actual moving speed of the carriage. The flowchart explaining the processing routine which a control part performs in order to determine irradiation intensity. (A) is a schematic diagram showing how the carriage moves, (b) is a timing chart showing changes in the actual movement speed of the carriage, and (c) is a timing chart showing changes in irradiation intensity. In a modification, the map referred when determining an intensity difference. The top view which shows schematic structure of the liquid injection part of another modification.

Hereinafter, an embodiment in which a liquid ejecting apparatus is embodied in an ink jet printer (hereinafter also referred to as “printer”) will be described with reference to the drawings.
As shown in FIG. 1, a printer 11 as an example of a liquid ejecting apparatus includes a main body case 12 having a substantially rectangular box shape. A support base 13 extends along the scanning direction X, which is the longitudinal direction, of the lower portion of the main body case 12. On the support base 13, the medium P is fed in the transport direction Y as an example of the second direction by a paper feed mechanism (not shown) based on driving of a paper feed motor 14 provided at the lower back of the main body case 12. The

  A guide shaft 15 is laid along the scanning direction X above the support base 13 in the main body case 12. A carriage 16 is supported on the guide shaft 15 so as to be capable of reciprocating in the scanning direction X. The carriage 16 is movable in the scanning direction + X (right direction in FIG. 1) and the scanning direction −X (left direction in FIG. 1).

  A driving pulley 17a and a driven pulley 17b are rotatably supported at positions corresponding to both ends of the guide shaft 15 on the inner surface of the rear wall of the main body case 12. An output shaft of a carriage motor 19 serving as a driving source when the carriage 16 is reciprocated is connected to the driving pulley 17a. An endless timing belt 18 partially connected to the carriage 16 is wound between the pair of pulleys 17a and 17b. Therefore, the carriage 16 moves in the scanning direction X through the endless timing belt 18 while being guided by the guide shaft 15 by driving the carriage motor 19. Further, an encoder scale 21 having a large number of slits that open at a constant pitch along the scanning direction X is stretched along the scanning direction X above the pulleys 17 a and 17 b and the timing belt 18.

  On the lower surface side of the carriage 16, a first ejection head 31 that ejects UV curable ink as an example of a photocurable liquid and a second ejection head 32 that ejects the UV curable ink are provided. Further, an irradiator 40 that irradiates UV onto the ink ejected from the first ejection head 31 and the second ejection head 32 onto the medium P is provided on the lower surface side of the carriage 16.

  An ink cartridge 22 for supplying ink to the first ejection head 31 and the second ejection head 32 is detachably attached to the upper side of the carriage 16. The ink in the ink cartridge 22 is supplied from the ink cartridge 22 to the first ejection head 31 and the second ejection head 32 by driving a piezoelectric element (not shown) provided in the first ejection head 31 and the second ejection head 32. . The ink supplied to the first ejecting head 31 and the second ejecting head 32 is applied to the medium P fed onto the support base 13 from a plurality of nozzles formed on the first ejecting head 31 and the second ejecting head 32. By being ejected, printing is performed on the medium P.

  In addition, an encoder sensor 23 is mounted on the rear side of the carriage 16 so as to face the encoder scale 21. When the carriage 16 moves in the scanning direction X, the encoder sensor 23 emits light to the encoder scale 21 and detects light passing through the slit. The encoder scale 21 and the encoder sensor 23 constitute a linear encoder 24 for detecting the position of the carriage 16 in the scanning direction X.

  In a home position area (non-printing area) that does not correspond to the medium P located at the right end in the main body case 12, a maintenance mechanism 25 that performs maintenance such as cleaning for the first ejection head 31 and the second ejection head 32. Is provided.

  Next, with reference to FIG. 2, the first and second ejection heads 31 and 32 and the irradiator 40 provided on the lower surface side of the carriage 16 will be described in detail. FIG. 2 is a partial top view of the carriage 16 in which a part of the configuration is omitted for easy understanding.

  As shown in FIG. 2, the first ejection head 31 is formed with a plurality of nozzle rows 33 composed of a number of nozzles that eject UV curable ink, and the second ejection head 32 is similarly provided with UV curable ink. A plurality of nozzle rows 34 composed of a number of nozzles to be ejected are formed. The irradiator 40 includes a first irradiator 41 (41A, 41B) that can irradiate the ink ejected from the first ejecting head 31 and a second irradiator that can irradiate the ink ejected from the second ejecting head 32. 2 irradiators 42 (42A, 42B). The irradiator 40 includes a third irradiator 43 (43A, 43B) that can irradiate the ink ejected from the first ejection head 31 and the second ejection head 32 with UV. In the present embodiment, the first irradiator 41, the second irradiator 42, and the third irradiator 43 change the supply current to the irradiators 41 to 43, such as UVLEDs (ultraviolet light emitting diodes), for example. The light source can change the irradiation intensity.

  The first ejection head 31 is disposed at a different position in the scanning direction X with respect to the second ejection head 32, and is disposed on the upstream side in the transport direction Y. At this time, the downstream end nozzle in the nozzle row 33 of the first ejection head 31 and the upstream end nozzle in the nozzle row 34 of the second ejection head 32 are continuous in the transport direction Y. For this reason, compared with the case where a single ejection head is used, the length of the nozzle row in the transport direction Y can be substantially doubled, and the carriage 16 in the scanning direction X can be moved once. The range in which ink can be ejected in the transport direction Y can be widened. Moreover, compared with the case where the ejection head in which the nozzle row twice the length of the nozzle rows 33 and 34 is formed is used, it is excellent in terms of maintainability.

  The first irradiator 41, the second irradiator 42, and the third irradiator 43 are arranged on both sides of the carriage 16 in the scanning direction X in a state of being arranged from the upstream side in the transport direction Y. The first irradiator 41A is disposed on the scanning direction −X side of the first ejection head 31, and the first irradiator 41B is spaced from the first ejection head 31 on the scanning direction + X side of the first ejection head 31. Are arranged. For this reason, when viewed from the scanning direction X, the first ejection head 31, the first irradiator 41A, and the first irradiator 41B are arranged so as to overlap in the transport direction Y. In the scanning direction X, the distance L1A from the center of the first irradiator 41A to the center of the first ejection head 31 is shorter than the distance L1B from the center of the first irradiator 41B to the center of the first ejection head 31. It has become.

  The second irradiator 42A is disposed on the scanning direction −X side of the second ejection head 32 with a space from the second ejection head 32, and the second irradiator 42B is disposed on the scanning direction + X side of the second ejection head 32. Has been. For this reason, when viewed from the scanning direction X, the second ejection head 32, the second irradiator 42A, and the second irradiator 42B are arranged so as to overlap in the transport direction Y. In the scanning direction X, the distance L2A from the center of the second irradiator 42A to the center of the second ejection head 32 is longer than the distance L2B from the center of the second irradiator 42B to the center of the second ejection head 32. It has become.

  In the following description, the distance L1A from the center of the first irradiator 41A to the center of the first ejection head 31 in the scanning direction X is simply the distance L1A from the first irradiator 41A to the first ejection head 31. Also called. The same applies to the distances L1B, L2A, and L2B. Incidentally, the reference of the distances L1A, L1B, L2A, and L2B may not be the center of the first ejection head 31 and the like.

  The first irradiator 41A and the second irradiator 42A irradiate the ink ejected by the first ejection head 31 and the second ejection head 32 when the carriage 16 moves in the scanning direction + X. It is provided for precuring the ink. On the other hand, when the carriage 16 moves in the scanning direction −X, the first irradiator 41B and the second irradiator 42B irradiate the ink ejected by the first ejection head 31 and the second ejection head 32 with UV, It is provided for pre-curing the ink. For this reason, for example, when the carriage 16 moves in the scanning direction + X, UV is irradiated from the first irradiator 41A and the second irradiator 42A provided in the rear in the moving direction, and forward in the moving direction. UV is not irradiated from the provided first irradiator 41B and second irradiator 42B. Here, the preliminary curing is performed in order to suppress spreading of the ink on the medium P by irradiating the ink jetted onto the medium P with a relatively weak UV and curing the surface of the ink. Is. In the following description, the irradiation intensity when the first irradiator 41 emits UV is also referred to as “first irradiation intensity I1”, and the irradiation intensity when the second irradiator 42 irradiates UV is “second”. Also referred to as “irradiation intensity I2”.

  Further, the third irradiator 43 is provided to further irradiate the ink preliminarily cured by the UV irradiation from the first irradiator 41 and the second irradiator 42 and to fully cure the ink. For this reason, in order to cure the ink ejected onto the medium P more reliably, the irradiation intensity of the third irradiator 43 is compared with the irradiation intensities I1 and I2 of the first irradiator 41 and the second irradiator 42. It is preferable that the setting is made strong. Here, the main curing means that the precured ink is irradiated with relatively strong UV to be cured to the inside of the ink.

  Thus, when the carriage 16 moves in the scanning direction + X as an example of the first direction, the distance from the first irradiator 41 </ b> A that irradiates the ink ejected by the first ejection head 31 to the first ejection head 31. L1A is shorter than the distance L2A from the second irradiator 42A that irradiates UV to the ink ejected by the second ejection head 32 to the second ejection head 32. In this regard, when the carriage 16 moves in the scanning direction + X (first direction), the first ejection head 31 is the “first ejection section”, the second ejection head 32 is the “second ejection section”, and the first irradiation. The device 41A corresponds to an example of a “first irradiation unit”, and the second irradiation device 42 corresponds to an example of a “second irradiation unit”. On the other hand, when the carriage 16 moves in the scanning direction −X as an example of the first direction, the second ejecting head 32 irradiates the ink ejected by the second ejecting head 32 to the second ejecting head 32. The distance L2B is shorter than the distance L1B from the first irradiator 41B that irradiates UV to the ink ejected by the first ejection head 31 to the first ejection head 31. In this regard, when the carriage 16 moves in the scanning direction −X (first direction), the first ejection head 31 is the “second ejection section”, the second ejection head 32 is the “first ejection section”, and the first The irradiator 41 corresponds to an example of a “second irradiator”, and the second irradiator 42 corresponds to an example of a “first irradiator”. In this embodiment, since the carriage 16 moves relative to the medium P in the scanning direction X by driving the carriage motor 19, the carriage motor 19 corresponds to an example of a “relative movement unit”.

Next, the electrical configuration of the printer 11 will be described.
As shown in FIG. 3, the printer 11 includes a control unit 50 that performs overall control of the printer 11, a storage unit 51 that stores ink types and medium types set in the printer 11, and a user's ink types and medium types. And an acquisition unit 52 that acquires information. The acquisition unit 52 may be, for example, a touch panel type liquid crystal display, or may be a computer electrically connected to the printer 11. The control unit 50 includes a paper feed motor 14, a carriage motor 19, a linear encoder 24, a first ejection head 31, a second ejection head 32, a first irradiator 41, a second irradiator 42, a third irradiator 43, The acquisition unit 52 is electrically connected. The control unit 50 can receive an electrical signal from each of these components, or transmit and control the electrical signal. For this reason, the control part 50 can change the irradiation intensity | strength with respect to the ink injected to the medium P by controlling the electric current supplied with respect to the irradiation devices 41-43. Further, the control unit 50 can calculate the moving speed of the carriage 16 by dividing the displacement amount when the carriage 16 is displaced by the time required for the displacement based on the detection result of the linear encoder 24. . In this embodiment, the linear encoder 24 and the control unit 50 correspond to an example of a “measurement unit” that calculates the moving speed of the carriage 16.

  Next, with reference to FIGS. 4A to 4C, the curing characteristics indicating changes in the dot form (dot area) of the UV curable ink with time will be described. Hereinafter, in order to facilitate the understanding of the description, the description will be made focusing on the dot area as an example of the dot form.

  As indicated by the solid line in FIG. 4A, the ink ejected from the nozzles 33 and 34 of the first ejection head 31 and the second ejection head 32 onto the surface of the medium P is irradiated with UV after being ejected. As the time elapses, the area gradually spreads on the medium P, and the dot area increases. Further, the change in the dot area also changes depending on the intensity of irradiation applied to the ink.

First, with reference to FIG. 4A, a description will be given of a change in dot area of the same ink when the ink is irradiated with UV of different irradiation intensity at the same timing.
As indicated by a solid line in FIG. 4A, when the ink is not irradiated with UV, the dot area of the ink does not change (the ink is pre-cured). At the second timing t12, the dot area of the ink is The area is A1. Further, as indicated by a one-dot chain line in FIG. 4A, when the ink is irradiated with UV at a relatively weak irradiation intensity at the first timing t11, the dot area of the ink is UV at the second timing t12. The area A2 is smaller than the area A1 when not irradiated. Further, as indicated by a two-dot chain line in FIG. 4A, when the ink is irradiated with UV at a relatively strong irradiation intensity at the first timing t11, the dot area of the ink is compared at the second timing t12. The area A3 is smaller than the area A2 when UV is irradiated with a relatively weak irradiation intensity. As described above, even when the UV irradiation timing (first timing t11) is the same, when the UV irradiation intensity is different, the dot area changes when the ink is pre-cured (second timing t12). Specifically, when the UV irradiation intensity is high, the dot area when the ink is precured is smaller than when the irradiation intensity is low.

Next, with reference to FIG. 4B, a change in the dot area of the ink when the ink having the same irradiation intensity UV is irradiated at different timings will be described.
As indicated by a solid line in FIG. 4B, when the ink is not irradiated with UV, the dot area of the ink becomes the area A1 at the third timing t23 when the ink is pre-cured. Further, as indicated by a two-dot chain line in FIG. 4B, when the ink is irradiated with UV at the relatively early first timing t21, the dot area of the ink does not irradiate with UV at the third timing t23. The area A3 is smaller than the area A1. Further, as indicated by a one-dot chain line in FIG. 4B, when the ink is irradiated with UV at the second timing t22 later than the first timing t21, the dot area of the ink is UV at the third timing t23. The area A2 is smaller than the area A1 when the UV is not irradiated and is larger than the area A3 when the UV is irradiated at the first timing t21. Thus, even when the UV irradiation intensity is the same, if the UV irradiation timing is different, the dot area of the ink changes when the ink is pre-cured (second timing t12). Specifically, when the UV irradiation timing is early, the dot area when the ink is preliminarily cured becomes smaller than when the UV irradiation timing is late.

  As described above, it is possible to change the dot area when the ink is pre-cured on the medium P by changing the UV irradiation intensity and the UV irradiation timing. For this reason, when UV is irradiated with a relatively weak irradiation intensity at a relatively early first timing t31 indicated by a two-dot chain line in FIG. 4C, and a relatively slow second indicated by a one-dot chain line in FIG. 4C. It is possible to equalize the dot area of the ink at the third timing t33 when the ink is pre-cured when the UV is irradiated with a relatively strong irradiation intensity at the timing t32. That is, even when ink is ejected from a plurality of ejection heads at the same timing and UV is irradiated to the ink at different timings, the dots when each ink is pre-cured by changing the UV irradiation intensity It becomes possible to make the area uniform.

  Here, as shown in FIG. 2, in the present embodiment, when the carriage 16 moves in the scanning direction + X to perform printing, the first irradiator 41A applies UV to the ink ejected by the first ejection head 31. The time until irradiation is shorter than the time until the second irradiator 42A irradiates the ink ejected by the second ejection head 32 with UV. In addition, when the carriage 16 moves in the scanning direction −X to perform printing, the time until the first irradiator 41 </ b> B irradiates the ink ejected by the first ejection head 31 is the second ejection head 32. It takes longer than the time until the second irradiator 42B irradiates UV to the ink ejected by the ink.

  Therefore, in the present embodiment, when the carriage 16 moves in the scanning direction + X to perform printing, the first irradiation intensity I1 of the first irradiator 41A having a short distance L1A to the first ejection head 31 is set to the first irradiation intensity I1. The distance L2A to the two ejection heads 32 is set to be weaker than the second irradiation intensity I2 of the second irradiator 42A. Further, when the carriage 16 moves in the scanning direction −X to perform printing, the second irradiation intensity I2 of the second irradiator 42B having a short distance L2B to the second ejection head 32 is set to the first ejection head 31. The distance L1B is made weaker than the first irradiation intensity I1 of the first irradiator 41B.

  Also, the time until the first irradiator 41 irradiates the ink ejected by the first ejecting head 31 and the time until the second irradiator 42 irradiates the ink ejected by the second ejecting head 32. The time difference is defined as “time difference”. Since the timing at which the first ejecting head 31 and the second ejecting head 32 eject ink is the same, the above time difference is that the second irradiator 42 irradiates UV after the first irradiator 41 irradiates UV. It is also the time until. For this reason, when the moving speed of the carriage 16 is fast, the time difference becomes small, and when the moving speed of the carriage 16 is slow, the time difference becomes large. Further, the closer this time difference is to “0 (zero)”, the dot area of the ink when the first irradiator 41 irradiates the ink ejected by the first ejection head 31 and the second ejection head 32. When the second irradiator 42 irradiates UV to the ejected ink, the difference from the dot area of the ink tends to be small. If the difference in dot area when UV is irradiated is small, it is desirable to reduce the intensity difference between the first irradiation intensity I1 and the second irradiation intensity I2.

  Therefore, in this embodiment, the intensity difference between the first irradiation intensity I1 and the second irradiation intensity I2 is changed according to the moving speed when the medium P and the carriage 16 move relative to each other. Specifically, the intensity difference is made smaller when the movement speed of the carriage 16 is fast than when the movement speed is slow.

  Next, the set moving speed Vc of the carriage 16 and the irradiation intensities I1 and I2 of the first irradiator 41 and the second irradiator 42 will be described with reference to FIG. The set moving speed Vc is, for example, the moving speed of the carriage 16 set according to the print mode designated by the user.

  As shown in FIG. 5, when the movement direction of the carriage 16 is the scanning direction + X, the first irradiator 41A and the second irradiation on the scanning direction −X side with respect to the first ejection head 31 and the second ejection head 32. UV is irradiated from the device 42A. On the other hand, when the movement direction of the carriage 16 is the scanning direction −X, the UV is emitted from the first irradiator 41B and the second irradiator 42B on the scanning direction + X side with respect to the first ejection head 31 and the second ejection head 32. Is irradiated. When the carriage 16 moves in the scanning direction + X, the time from when the first ejecting head 31 ejects ink to when the first irradiator 41 irradiates UV to the ink is equal to the second ejecting head 32. Becomes shorter than the time from when the ink is ejected to when the second irradiator 42 irradiates the ink with UV. Therefore, when the carriage 16 moves in the scanning direction + X, the first irradiator is used to make the first irradiation intensity I1 of the first irradiator 41A weaker than the second irradiation intensity I2 of the second irradiator 42A. The supply current Is for 41A is smaller than the supply current Is for the second irradiator 42A. Similarly, when the carriage 16 moves in the scanning direction −X, the second irradiation is performed in order to make the second irradiation intensity I2 of the second irradiation unit 42B weaker than the first irradiation intensity I1 of the first irradiation unit 41B. The supply current Is for the generator 42B is smaller than the supply current Is for the first irradiator 41B.

  When the set movement speed Vc of the carriage 16 is high, the first difference that is substantially proportional to the intensity difference between the first irradiation intensity I1 and the second irradiation intensity I2 is compared with the case where the set movement speed Vc is low. The current difference between the supply currents Is to the irradiator 41 and the second irradiator 42 is reduced. For example, when the set movement speed Vc of the carriage 16 is 100 mm / sec, the current difference of the supply current Is is 150 mA, and when the set movement speed Vc of the carriage 16 is 300 mm / sec, the current difference of the supply current Is is 30 mA.

  As described above, in the present embodiment, the set moving speed Vc of the carriage 16 is set according to the print mode designated by the user. Therefore, for example, when the user desires a high-quality print mode, the set movement speed Vc of the carriage 16 is low (for example, 100 mm / sec) in order to make the ink dots per unit area dense on the medium P. ). On the other hand, when the user desires a low image quality printing mode (high-speed printing mode), the setting movement speed Vc of the carriage 16 is high (for example, 300 mm) in order to roughen ink dots per unit area on the medium P. / Sec). Thus, in the present embodiment, the set movement speed Vc determined according to the print mode corresponds to an example of “set relative movement speed”.

  The spreading mode (curing mode) of the ink on the medium P varies depending on the ink type and the medium type. For this reason, in this embodiment, it is assumed that a table in which the magnitude of the supply current Is to the irradiators 41 and 42 is different is stored in the storage unit 51 for each ink type and medium type. Furthermore, it is assumed that the table stored in the storage unit 51 is obtained in advance by performing an experiment. Incidentally, the ink type refers to, for example, a UV curable ink having a different content of the ultraviolet curable resin, and the medium type refers to, for example, plain paper, glossy paper, and a resin film.

  Further, when the supply current Is to the irradiators 41 and 42 is increased as a whole, the dot form of the ink ejected onto the medium P is cured in a substantially hemispherical shape, so that it is possible to perform printing with weak glossiness. is there. Further, when the current value for the irradiators 41 and 42 is lowered as a whole, the dot form of the ink ejected onto the medium P is cured in a flat state, so that printing can be performed with a strong gloss feeling. . That is, in the printer 11 of the present embodiment, it is possible to perform printing with different glossiness by changing the irradiation intensities I1 and I2 of the irradiators 41 and 42.

  By the way, in the printer 11 of this embodiment, when the carriage 16 reciprocates in the scanning direction X, the first ejection head 31 and the second ejection head 32 eject ink onto the medium P, and the irradiators 41 to 43 serve as the medium. Printing is performed by irradiating the ink ejected onto P with UV. For this reason, the movement direction of the carriage 16 is changed from the scanning direction + X to the scanning direction −X on one end side in the scanning direction X, and the moving direction is changed from the scanning direction −X to the scanning direction −X on the other end side in the scanning direction X. It will be changed to + X. For example, when the movement direction of the carriage 16 is changed from the scanning direction + X to the scanning direction −X, the carriage 16 is gradually decelerated on one end side in the scanning direction X, and the movement speed is set to “0 (zero)”. It stops by being done. Subsequently, the carriage 16 is gradually accelerated in the scanning direction −X and moves in the scanning direction −X. Thus, the carriage 16 is accelerated and decelerated so as to reverse the moving direction at one end side and the other end side in the scanning direction X, so that the actual moving speed of the carriage 16 is set according to the printing mode. A state of being slower than Vc may occur.

  If the carriage 16 is accelerated or decelerated while facing the medium P, when the carriage 16 moves while accelerating or decelerating, the irradiation time of UV with respect to the medium part facing the irradiators 41 and 42 is reduced. Becomes longer than the UV irradiation time when moving at the set moving speed Vc. In this case, the cured state of the ink ejected onto the medium P becomes non-uniform between the medium part having a long UV irradiation time and the medium part having a short irradiation time. Such a situation can be avoided by decelerating (and accelerating) after the carriage 16 moves until it does not face the medium P in the scanning direction X, but in this case, in the scanning direction X, This is not preferable because problems such as an increase in the size of the printer 11 and a decrease in printing throughput occur.

  Therefore, in the present embodiment, when the actual moving speed of the carriage 16 (hereinafter also referred to as “actual moving speed Vm”) is slower than the set moving speed Vc that is the set relative moving speed, the first irradiation intensity I1 and The second irradiation intensity I2 was weakened. That is, when the carriage 16 moves at a speed slower than the set moving speed Vc and the irradiation time becomes long, the carriage 16 is set to the set moving speed Vc by decreasing the first irradiation intensity I1 and the second irradiation intensity I2. The difference between the case of UV irradiation with the first irradiation intensity I1 and the second irradiation intensity I2 and the cured state of the ink is prevented. In the present embodiment, when the carriage 16 is accelerated or decelerated on both sides in the scanning direction X, the first irradiation intensity I1 of the first irradiator 41 and the second irradiation intensity I2 of the second irradiator 42 are weakened. It will be. In the present embodiment, the actual moving speed Vm corresponds to an example of “actual relative moving speed”.

  FIG. 6 shows a map for determining the gain value Gn to be multiplied by the first irradiation intensity I1 of the first irradiator 41 and the second irradiation intensity I2 of the second irradiator 42 in accordance with the actual moving speed Vm of the carriage 16. It is. For example, when the actual moving speed Vm of the carriage 16 is not decelerated, that is, when the actual moving speed Vm of the carriage 16 is the set moving speed Vc, the gain value Gn is set to “1.0”, and the first irradiator 41 The first irradiation intensity I1 and the second irradiation intensity I2 of the second irradiator 42 are not changed. On the other hand, when the actual moving speed Vm of the carriage 16 is half the set moving speed Vc, the gain value Gn is set to “0.5”, and the first irradiation intensity I1 and the first irradiation unit 41 are The second irradiation intensity I2 of the second irradiator 42 is halved. Thus, by correcting the first irradiation intensity I1 of the first irradiator 41 and the second irradiation intensity I2 of the second irradiator 42 by the gain value Gn obtained using the map shown in FIG. Progress of the cured state of the ink irradiated with UV when decelerating is suppressed.

  Next, a processing routine executed by the control unit 50 of the present embodiment will be described with reference to a flowchart shown in FIG. This processing routine is a processing routine that is sequentially executed during printing.

  As shown in FIG. 7, the control unit 50 obtains the set movement speed Vc of the carriage 16 determined from the print mode designated by the user (step S11). Subsequently, the control unit 50 determines a table (see FIG. 5) corresponding to the ink type and medium type used for the current printing acquired by the acquisition unit 52 (step S12). Then, the control unit 50 determines the supply current Is1 for the first irradiator 41 and the supply current Is2 for the second irradiator 42 based on the set moving speed Vc of the carriage 16 (step S13). Specifically, referring to the table shown in FIG. 5, the supply current Is1 and the supply current Is2 are determined based on the set movement speed Vc of the carriage 16 and the movement direction of the carriage 16.

  Subsequently, the control unit 50 acquires the actual moving speed Vm of the carriage 16 (step S14). Then, the control unit 50 refers to the map shown in FIG. 6 and acquires the gain value Gn based on the set moving speed Vc and the actual moving speed Vm (step S15). Subsequently, the control unit 50 sets a value obtained by multiplying the supply current Is1 acquired in step S13 by the gain value Gn acquired in step S15 as a new supply current Is1 (step S16), and the supply acquired in step S13. A value obtained by multiplying the current Is2 by the gain value Gn acquired in step S15 is set as a new supply current Is2 (step S17).

  Then, the control unit 50 determines whether or not the printing is finished (step S18), and when the printing is finished (step S18: YES), the process is once finished. On the other hand, when printing has not ended (step S18: NO), the control unit 50 shifts the process to step S13.

  Next, the operation of the printer 11 of this embodiment will be described with reference to FIG. In FIG. 8A, a part of the configuration of the carriage 16 such as the third irradiator 43 is omitted for easy understanding of the explanation. Further, when the printer 11 performs printing, the carriage 16 reciprocates in the scanning direction X while the medium P is intermittently transported in the transport direction Y, but in the following description, the state where the medium P is stopped The operation when the carriage 16 moves in the scanning direction + X will be described as a representative. 8B and 8C, a solid line indicates a case where the set movement speed Vc of the carriage 16 is a relatively slow set movement speed Vcl (for example, 100 mm / sec) when high-quality printing is performed. A case where the set moving speed Vc is set to a relatively fast set moving speed Vch (for example, 300 mm / sec) when printing with low image quality is indicated by a broken line.

  First, the case of a relatively slow set movement speed Vcl indicated by a solid line in FIG. 8 will be described. In this case, the supply current Is1 (for example, 50 mA) and the supply current Is2 (for example, 200 mA) are determined from the map shown in FIG. 5 corresponding to the set moving speed Vcl. That is, the first irradiation intensity I1l corresponding to the supply current Is1 and the second irradiation intensity I2l corresponding to the supply current Is2 are determined.

  As shown in FIGS. 8A to 8C, since the carriage 16 is stopped at the first timing t41, the actual movement speed Vm of the carriage 16 is “0 (zero)”. Therefore, the gain value Gn corresponding to the actual moving speed Vm of the carriage 16 is “0 (zero)”, and the first irradiation intensity I1 corresponding to the supply current Is1 multiplied by the gain value Gn is “0 (zero)”. It becomes. Similarly, the second irradiation intensity I2 corresponding to the supply current Is2 multiplied by the gain value Gn is “0 (zero)”. Further, during the period from the first timing t41 to the next second timing t42, the carriage 16 is gradually accelerated in the scanning direction + X, so that the gain value Gn is gradually increased according to the actual moving speed Vm. . That is, the first irradiation intensity I1 and the second irradiation intensity I2 corresponding to the supply currents Is1 and Is2 multiplied by the gain value Gn are gradually increased as the carriage 16 is accelerated.

  At the second timing t42, the actual moving speed Vm of the carriage 16 becomes the set moving speed Vc. Therefore, the gain value Gn corresponding to the actual moving speed Vm of the carriage 16 is “1”, and the first irradiation intensity I1 corresponding to the supply current Is1 multiplied by the gain value Gn is equal to the first irradiation intensity I1l. Similarly, the second irradiation intensity I2 corresponding to the supply current Is2 multiplied by the gain value Gn is equal to the second irradiation intensity I2l. Further, in the period from the second timing t42 to the next third timing t43, the state where the actual movement speed Vm is equal to the set movement speed Vc is continued, and thus the state where the gain value Gn is “1” continues. Is done. For this reason, the state in which the first irradiation intensity I1 is equal to the first irradiation intensity I1l is continued, and the state in which the second irradiation intensity I2 is equal to the second irradiation intensity I2l is continued.

  When the carriage 16 moves in the scanning direction + X, the timing at which the second irradiator 42A irradiates UV is later than the timing at which the first irradiator 41A irradiates UV. The dot area of the ink at the timing when the second irradiator 42 irradiates the UV becomes larger than the dot area of the ink at the timing when the UV is irradiated. Here, the ink ejected by the first ejection head 31 is irradiated with UV at the first irradiation intensity I1l which is weaker than the second irradiation intensity I2l, while the ink ejected by the second ejection head 32 has the first irradiation intensity. UV is irradiated at a second irradiation intensity I2l that is stronger than I1l. For this reason, the spreading speed of the ink ejected by the second ejection head 32 that is irradiated with UV at the second irradiation intensity I2l is the spreading speed of the ink ejected by the first ejection head 31 that is irradiated with UV at the first irradiation intensity I1l. Slower than speed. Therefore, even if there is a difference in the dot area at the timing of UV irradiation, the difference in the dot area of the ink in the cured state is suppressed. In this way, it is suppressed that the dot form of the ink cured on the medium P becomes non-uniform.

  Subsequently, at the third timing t43, the carriage 16 starts decelerating to change the moving direction from the scanning direction + X to the scanning direction −X. For this reason, during the period from the third timing t43 to the next fourth timing t44, the carriage 16 is gradually decelerated in the scanning direction + X, so that the gain value Gn corresponding to the actual moving speed Vm is gradually reduced. The That is, the first irradiation intensity I1 and the second irradiation intensity I2 corresponding to the supply currents Is1 and Is2 multiplied by the gain value Gn are gradually weakened as the carriage 16 decelerates. At the fourth timing t44, since the carriage 16 is stopped, the actual moving speed Vm is “0 (zero)”. Therefore, the gain value Gn becomes “0 (zero)”, and the first irradiation intensity I1 and the second irradiation intensity I2 corresponding to the supply currents Is1 and Is2 multiplied by the gain value Gn are both “0 (zero)”. It becomes.

  By the way, in the period from the first timing t41 to the second timing t42 and the period from the third timing t43 to the fourth timing t44, the first irradiation intensity I1 is weaker than the first irradiation intensity I1l. The second irradiation intensity I2 is made weaker than the second irradiation intensity I2l. This is because, during these periods, the actual movement speed Vm is slower than the set movement speed Vc, so that the UV irradiation time is longer than the period from the second timing t42 to the third timing t43. is there. That is, in the period from the first timing t41 to the second timing t42 and the period from the third timing t43 to the fourth timing t44, UV is emitted with a relatively weak irradiation intensity over a relatively long irradiation time. Irradiated to ink. On the other hand, in the period from the second timing t42 to the third timing t43, UV is irradiated to the ink with a relatively strong irradiation intensity over a relatively short irradiation time. In this way, the dot area is suppressed from becoming non-uniform during the period from the first timing t41 to the fourth timing t44 in which the actual moving speed Vm of the carriage 16 is different.

  On the other hand, in the case of a relatively fast set movement speed Vch indicated by a broken line in FIG. 8, the first irradiation intensity I1h (for example, 120 mA supply current Is) corresponding to the set movement speed Vch from the map shown in FIG. And a second irradiation intensity I2h (e.g., corresponding to a supply current Is of 150 mA) are determined. Here, the first irradiation intensity I1h in the case of the relatively fast set moving speed Vch is larger than the first irradiation intensity I1l in the case of the relatively slow setting moving speed Vcl, and the first irradiation intensity I1h in the case of the relatively fast set moving speed Vch. The 2 irradiation intensity I2h is smaller than the second irradiation intensity I2l in the case of the relatively slow set moving speed Vcl.

  At the first timing t41, since the actual moving speed Vm is “0 (zero)”, the gain value Gn also becomes “0 (zero)”, and the first current t1 corresponding to the supply currents Is1 and Is2 multiplied by the gain value Gn. Both the first irradiation intensity I1 and the second irradiation intensity I2 are “0 (zero)”. In the period from the first timing t41 to the next second timing t42, the gain value Gn gradually increases as the carriage 16 accelerates, so that the first irradiation intensity I1 and the second irradiation intensity I2 are gradually increased. Is done.

  At the second timing t42, since the actual moving speed Vm becomes equal to the set moving speed Vc, the gain value Gn becomes “1”, and the first irradiation intensity I1 corresponding to the supply current Is1 multiplied by the gain value Gn. Is equal to the first irradiation intensity I1h. Similarly, the second irradiation intensity I2 corresponding to the supply current Is2 multiplied by the gain value Gn is equal to the second irradiation intensity I2h. Further, in the period from the second timing t42 to the next third timing t43, the state in which the actual movement speed Vm is equal to the set movement speed Vc is continued, so the first irradiation intensity I1 is the first irradiation intensity I1h. The same state is continued, and the second irradiation intensity I2 is continuously equal to the second irradiation intensity I2h.

  As shown in FIG. 8C, in the period from the second timing t42 to the next third timing t43, the first irradiation intensity I1h and the second irradiation intensity in the case of the relatively fast set moving speed Vch. The intensity difference from I2h is smaller than the intensity difference between the first irradiation intensity I1l and the second irradiation intensity I2l in the case of the relatively slow set moving speed Vcl. This is because, when the set moving speed Vc is fast, the second ejecting head after the first irradiator 41 irradiates UV onto the ink ejected by the first ejecting head 31 than when the set moving speed Vc is slow. This is because the time until the second irradiator 42 irradiates the ink ejected by 32 with UV is shortened. As the time becomes shorter, the difference between the ink dot area at the timing when the first irradiator 41 irradiates UV and the ink dot area at the timing when the second irradiator 42 irradiates UV becomes smaller. Cheap. Therefore, when the set moving speed Vc is high, the difference in intensity between the first irradiation intensity I1 and the second irradiation intensity I2 is made smaller than when the set moving speed Vc is low, so that the dot form of the ink cured on the medium P is obtained. Is suppressed from becoming non-uniform.

  Subsequently, at the third timing t43, deceleration of the carriage 16 is started. Therefore, in the period from the third timing t43 to the next fourth timing t44, the gain value Gn gradually decreases as the carriage 16 decelerates, so that the first irradiation intensity I1 and the second irradiation intensity I2 gradually increase. Be weakened. At the fourth timing, since the actual moving speed Vm is “0 (zero)”, the gain value Gn is also “0 (zero)”, which corresponds to the supply currents Is1 and Is2 multiplied by the gain value Gn. The first irradiation intensity I1 and the second irradiation intensity I2 are both “0 (zero)”.

According to the above embodiment, the following effects can be obtained.
(1) When the carriage 16 moves in the scanning direction + X, the first irradiation intensity I1 of the first irradiator 41A having a short distance L1A to the first ejection head 31 is set to be long, and the distance L2A to the second ejection head 32 is long. It was made to be weaker than the second irradiation intensity I2 of the two irradiator 42A. Thereby, the spreading speed of the ink ejected by the second ejection head 32 irradiated with light at the second irradiation intensity I2 is the spreading speed of the ink ejected by the first ejection head 31 irradiated with light at the first irradiation intensity I1. It can be slower than the speed. Thus, there is a difference between the ink dot form on the medium P when the first irradiator 41 irradiates light and the ink dot form on the medium P when the second irradiator 42 irradiates light. Even if it occurs, it is possible to suppress a difference in the dot area (dot form) of the ink in the cured state. In this way, it is possible to prevent the dot area of the ink cured on the medium P from becoming uneven.

  (2) When the set movement speed Vc, which is the set relative movement speed, is fast, the first irradiator 41 irradiates light onto the ink ejected by the first ejection head 31 than when the set movement speed Vc is slow. Thus, the time until the second irradiator 42 irradiates the ink ejected by the second ejection head 32 is shortened. As this time becomes shorter, the dot area of the ink when the first irradiator 41 irradiates light onto the ink ejected by the first ejecting head 31, and the second irradiator 42 against the ink ejected by the second ejecting head 32. The difference from the dot area of the ink when irradiating light tends to be small. Therefore, when the set moving speed Vc is fast, the intensity difference is made smaller than when the set moving speed Vc is slow, and compared with the case where a constant intensity difference is used regardless of the set moving speed Vc. It is possible to prevent the dot area of the ink cured in step 1 from becoming uneven.

  (3) When the carriage 16 is accelerated and decelerated in the scanning direction + X side and the scanning direction −X side, if the actual movement speed Vm is slower than the set movement speed Vc that is the set relative movement speed, the first irradiation intensity I1 In addition, the second irradiation intensity I2 was weakened. That is, when the actual movement speed Vm becomes slower than the set movement speed Vc when the carriage 16 accelerates or decelerates on both sides in the scanning direction X, the irradiation intensities I1 and I2 are reduced. According to this, the dot area of the ink cured on the medium P becomes nonuniform when the actual moving speed Vm is equal to the set moving speed Vc and when the actual moving speed Vm is slower than the set moving speed Vc. This can be suppressed.

  (4) The intensity difference between the first irradiation intensity I1 and the second irradiation intensity I2 is changed by changing the table shown in FIG. 5 according to the ink type and the medium type. For this reason, even if it is a case where the hardening characteristic of an ink changes by changing the kind of medium P, it can suppress that the dot area of the ink hardened | cured on the medium P becomes non-uniform | heterogenous.

  (5) In the transport direction Y, the first ejection head 31 and the second ejection head 32 are disposed at different positions, and the first irradiator 41 and the second irradiator 42 are disposed at different positions. Further, when viewed from the scanning direction X, the first ejection head 31 and the first irradiator 41 are disposed so as to overlap each other, and the second ejection head 32 and the second irradiator 42 are disposed so as to overlap each other. For this reason, the second irradiator 42 irradiates the ink ejected by the first ejecting head 31 while suppressing the first irradiator 41 from irradiating the ink ejected by the second ejecting head 32 with light. Can be suppressed.

In addition, you may change the said embodiment as follows.
When the set moving speed Vc, which is the set relative moving speed, is fast, the intensity difference between the first irradiation intensity I1 and the second irradiation intensity I2 does not have to be smaller than when the set moving speed Vc is slow. In this case, the strength difference may be obtained according to the curing characteristics for each ink type and medium type.

  FIG. 9 shows three curing characteristics X1, X2, and X3 with respect to the passage of time after ink is ejected onto the medium P at time “0 (zero)”. That is, the first curing characteristic X1 in which the dot area of the ink increases relatively slowly, the second curing characteristic X2 in which the dot area of the ink increases more steeply than the first curing characteristic X1, and the first A third curing characteristic X3 in which the dot area of the ink increases more steeply than the curing characteristic X1 and the second curing characteristic X2 is shown. Here, consider a case where the set movement speed Vc of the carriage 16 is high and a case where the set movement speed Vc of the carriage 16 is low. That is, the first irradiator 41 irradiates UV at the first timing t51 and the second irradiator 42 irradiates UV at the next second timing t52, and the first irradiator at the second timing t52. Consider a case where 41 irradiates UV and the second irradiator 42 irradiates UV at the next third timing t53.

  When the set moving speed Vc of the carriage 16 is fast, in the first curing characteristic X1, the dot area when the first irradiator 41 irradiates UV and the dot area when the second irradiator 42 irradiates UV. , That is, the dot area increment ΔX with respect to the passage of time from the first timing t51 to the second timing t52 becomes an increment ΔX1h. Similarly, in the second curing characteristic X2, the dot area increment ΔX with respect to the passage of time from the first timing t51 to the second timing t52 becomes the increment ΔX2h, and in the third curing characteristic X3, the first timing t51. The increment ΔX of the dot area with respect to the elapse of time from the first timing t52 to the second timing t52 is an increment ΔX3h. On the other hand, when the set movement speed Vc of the carriage 16 is slow, the first curing characteristics X1 indicate that the dot area when the first irradiator 41 irradiates UV and the second irradiator 42 when irradiating UV. The dot area difference ΔX with respect to the dot area difference, that is, the passage of time from the second timing t52 to the third timing t53 is the increment ΔX1l. Similarly, in the second curing characteristic X2, the dot area increment ΔX with respect to the passage of time from the second timing t52 to the third timing t53 becomes the increment ΔX2l, and in the third curing characteristic X3, the second timing t52. The increment ΔX of the dot area with respect to the elapse of time from to the third timing t53 becomes the increment ΔX3l.

  For this reason, in the first curing characteristic X1, the increment ΔX1h when the set movement speed Vc of the carriage 16 is fast is smaller than the increment ΔX1l when the set movement speed Vc is slow. That is, when the set moving speed Vc is high, the ink dots at the timing when the first irradiator 41 irradiates UV and the timing when the second irradiator 42 irradiates UV is higher than when the set moving speed Vc is low. It can be said that the difference in area is small. Further, in the second curing characteristic X2, the increment ΔX2h when the set movement speed Vc of the carriage 16 is fast is equal to the increment ΔX2l when the set movement speed Vc is slow. That is, in the case where the set moving speed Vc is fast and the case where the set moving speed Vc is slow, the dot area of the ink at the timing when the first irradiator 41 irradiates UV and the timing when the second irradiator 42 irradiates UV. It can be said that the difference is difficult to occur. Further, in the third curing characteristic X3, the increment ΔX3h when the set movement speed Vc of the carriage 16 is fast is larger than the increment ΔX3l when the set movement speed Vc is slow. That is, when the set moving speed Vc is high, the ink dots at the timing when the first irradiator 41 irradiates UV and the timing when the second irradiator 42 irradiates UV is higher than when the set moving speed Vc is low. It can be said that the difference in area is large.

  Thus, depending on the curing characteristics X1 to X3, the increase ΔX decreases as the set movement speed Vc of the carriage 16 becomes faster. Therefore, the strength difference may be reduced, or the increase ΔX increases as the set movement speed Vc of the carriage 16 increases. In some cases, it is better to increase the strength difference. However, in any case, in each of the curing characteristics X1 to X3, in order to make the ink area uniform when cured, the intensity difference is reduced when the increment ΔX is small, and the increment ΔX is large. It is better to increase the strength difference. Therefore, the dot area increment ΔX for each curing characteristic may be used to make the intensity difference smaller when the increment ΔX is small than when the increment ΔX is large. For example, it is assumed that a reference increment and a reference strength difference with respect to a reference set moving speed Vc are determined for each of the curing characteristics X1 to X3. Then, the current increment ΔX with respect to the current set moving speed Vc is calculated, and if the current increment ΔX is larger than the reference increment, the current intensity difference is made larger than the reference strength difference, and the current increment ΔX is larger than the reference increment. If is small, the current intensity difference may be made smaller than the reference intensity difference. According to this, since there are a plurality of ink types and medium types handled by the printer 11, even when there are a plurality of curing characteristics in which the tendency of change in the dot area of the ink with respect to the passage of time is significantly different, the curing is performed on the medium P. It is possible to further suppress the non-uniform dot area of the liquid. In this case, as an alternative to the dot area, the dot diameter may be used, or the dot thickness may be used.

  As shown in FIG. 10, the printer 11 may be a so-called line head type printer having a liquid ejecting section 60 that is fixedly arranged instead of the carriage 16 that reciprocates in the scanning direction X. In this case, the liquid ejecting unit 60 includes a plurality of ejecting heads 61 and 62 provided so that the nozzle rows 63 and 64 are continuous along the width direction Z of the medium P perpendicular to the transport direction Y of the medium P, and It is preferable that the heads 61 and 62 include a plurality of irradiators 71 and 72 that can irradiate the ink jetted onto the medium P with UV. In the liquid ejecting unit 60, the first ejecting head 61 is preferably provided on the downstream side in the transport direction Y in a state adjacent to the second ejecting head 62 in the width direction Z. 71 and the second irradiator 72 are preferably provided on the downstream side in the transport direction Y of the first ejection head 61 and the second ejection head 62 in a state of being adjacent to each other in the width direction Z. In the transport direction Y, the distance L1 from the center of the first irradiator 71 to the center of the first ejection head 61 is shorter than the distance L2 from the center of the second irradiator 72 to the center of the second ejection head 62. It is preferable. In this case, the transport direction Y of the medium P corresponds to an example of “first direction”, and the width direction Z of the medium P corresponds to an example of “second direction”. Further, since the medium P is relatively transported in the transport direction Y with respect to the liquid ejecting section 60 that is fixedly arranged, the liquid ejecting section 60 moves relative to the medium P, so that the medium P is transported. The paper feed motor 14 that is driven to do this corresponds to an example of a “relative movement unit”.

  In the liquid ejecting unit 60 illustrated in FIG. 10, the first ejecting head 61 and the second ejecting head 62 eject ink to the medium P to be transported, and the first irradiator 71 and the first ejector to the ink ejected to the medium P. Printing is performed by the two irradiator 72 irradiating UV. Even in this case, the intensity difference between the first irradiation intensity I1 and the second irradiation intensity I2 is changed according to the conveyance speed of the medium P as an example of the “set relative movement speed”, thereby achieving the effect of the above embodiment. The same effects as (1) to (5) can be obtained.

  In the printer shown in FIG. 10, printing may be performed by moving the liquid ejecting unit 60 in the direction opposite to the transport direction Y while the medium P is moved in the transport direction Y. That is, both the medium P and the liquid ejecting unit 60 may be moved. In this case, it is preferable to further include a drive source that moves the liquid ejecting unit 60 in the direction opposite to the transport direction Y.

The irradiators 41 to 43, 71, and 72 may be light sources capable of irradiating UV other than UVLED, such as metal halide lamps and mercury lamps, as long as the irradiation intensity can be controlled.
The acquisition unit 52 may be a sensor such as a camera. In other words, the printer 11 (control unit 50) itself may acquire information such as ink type and medium type regardless of user information input.

  When determining the irradiation intensities I1 and I2 corresponding to the set moving speed Vc of the carriage 16 with reference to the table shown in FIG. 5, if there is no set moving speed Vc corresponding to the table shown in FIG. The first irradiation intensity I1 and the second irradiation intensity I2 may be calculated by linear interpolation based on the set moving speed Vc.

  As an alternative to the table shown in FIG. 5, the relational expression between the set movement speed Vc of the carriage 16 and the first irradiation intensity I1 and the relational expression between the setting movement speed Vc and the second irradiation intensity I2 are stored in the storage unit 51. You may make it do. In this case, the relational expression may be a linear expression or a higher-order expression of a second or higher order.

-You may make it change the irradiation intensity | strength of the irradiation devices 41-43, 71, 72 with other control methods, such as PWM control.
The actual moving speed Vm may not be calculated based on the detection result of the linear encoder 24. In this case, it is desirable to provide a speed sensor as an example of a measurement unit that measures the actual moving speed Vm.

In the table shown in FIG. 5, the set moving speed Vc of the carriage 16 and the magnitude of the supply current Is to the irradiators 41 and 42 are examples, and may be arbitrarily changed.
As an alternative to the dot area, an ink dot diameter, an ink dot thickness (height), or the like as an example of a dot form may be used.

  The printer 11 may be a printer that ejects ink that is cured by irradiating light other than UV. The printer 11 may be a liquid ejecting apparatus that ejects liquid other than ink. In this case, it is desirable that the other liquid is cured by irradiation with UV or other light other than UV.

  The liquid ejecting apparatus may be a liquid ejecting apparatus that ejects or discharges liquid other than ink. Note that the state of the liquid ejected as a minute amount of liquid droplets from the liquid ejecting apparatus includes a granular shape, a tear shape, and a thread-like shape. The liquid here may be a material that can be cured by irradiation with light such as UV and can be ejected from the liquid ejecting apparatus. For example, it may be in a state in which the substance is in a liquid phase, such as a liquid with high or low viscosity, sol, gel water, other inorganic solvents, organic solvents, solutions, liquid resins, liquid metals (metal melts ). Further, not only a liquid as one state of a substance but also a substance in which particles of a functional material made of a solid such as a pigment or metal particles are dissolved, dispersed or mixed in a solvent is included. Typical examples of the liquid include ink and liquid crystal as described in the above embodiment. As a specific example of the liquid ejecting apparatus, for example, a liquid containing a material such as an electrode material or a color material used for manufacturing a liquid crystal display, an EL (electroluminescence) display, a surface emitting display, or a color filter in a dispersed or dissolved form. There is a liquid ejecting apparatus for ejecting the liquid. Further, it may be a liquid ejecting apparatus that ejects a bio-organic matter used for biochip manufacturing, a liquid ejecting apparatus that ejects liquid as a sample that is used as a precision pipette, a printing apparatus, a micro dispenser, or the like. In addition, transparent resin liquids such as UV curable resin to form liquid injection devices that pinpoint lubricant oil onto precision machines such as watches and cameras, and micro hemispherical lenses (optical lenses) used in optical communication elements. May be a liquid ejecting apparatus that ejects the liquid onto the substrate. Further, it may be a liquid ejecting apparatus that ejects an etching solution such as acid or alkali in order to etch a substrate or the like.

  DESCRIPTION OF SYMBOLS 11 ... Printer (an example of a liquid ejecting apparatus) 31, 61 ... 1st ejecting head, 32, 62 ... 2nd ejecting head, 41, 71 ... 1st irradiator, 42, 72 ... 2nd irradiator, I1 ... 1st 1 irradiation intensity, I2 ... second irradiation intensity, 16 ... carriage (an example of a liquid ejecting unit) 19 ... carriage motor (an example of a relative movement unit), 24 ... linear encoder (an example of a measurement unit), 50 ... control unit, 51 ... storage unit, 52 ... acquisition unit, 60 ... liquid ejection unit, L1, L1A, L1B, L2, L2A, L2B ... distance, P ... medium, Vc ... movement speed (an example of set relative movement speed), Vm ... actual movement Speed (an example of an actual relative movement speed), X1 to X3: curing characteristics, ΔX: increment.

Claims (6)

First and second ejection units that eject a photocurable liquid onto the medium, and a first irradiation unit that can irradiate the liquid ejected from the first ejection unit with a first irradiation intensity, and the first A liquid ejecting unit having a second irradiation unit capable of irradiating the liquid ejected from the two ejecting units with a second irradiation intensity;
A control unit for controlling the first irradiation intensity and the second irradiation intensity;
A relative moving unit that moves at least one of the medium and the liquid ejecting unit in a first direction and relatively moves the medium and the liquid ejecting unit,
In the second direction orthogonal to the first direction, the first injection unit and the second injection unit are arranged at different positions, and the first irradiation unit and the second irradiation unit are different from each other. Placed in
In the first direction, a distance from the first irradiation unit to the first injection unit is shorter than a distance from the second irradiation unit to the second injection unit,
The control unit changes an intensity difference between the first irradiation intensity and the second irradiation intensity in accordance with a set relative movement speed when the set medium and the liquid ejecting unit relatively move. A liquid ejecting apparatus.   2. The liquid ejecting apparatus according to claim 1, wherein when the set relative movement speed is high, the control unit reduces the intensity difference as compared with a case where the set relative movement speed is low. A storage unit that stores a curing characteristic of the liquid indicating a change in dot area with time of the liquid sprayed on the medium;
Based on the curing characteristics, the control unit is configured such that the liquid dots with respect to the passage of time from the timing at which the first irradiation unit irradiates light to the liquid to the timing at which the second irradiation unit irradiates light to the liquid. Calculate the area increment,
The liquid ejecting apparatus according to claim 1, wherein when the dot area increment is small, the intensity difference is made smaller than when the dot area increment is large.   The first injection unit and the first irradiation unit are arranged so as to overlap each other when viewed from the first direction, and the second injection unit and the second irradiation unit are arranged so as to overlap each other. The liquid ejecting apparatus according to any one of claims 1 to 3. A measuring unit for measuring an actual relative moving speed between the medium and the liquid ejecting unit;
The control unit reduces the first irradiation intensity and the second irradiation intensity when the actual relative movement speed is slower than the set relative movement speed. The liquid ejecting apparatus according to any one of the above. An acquisition unit for acquiring the type of the medium;
The liquid ejecting apparatus according to claim 1, wherein the control unit changes the intensity difference according to a type of the medium acquired by the acquisition unit.