JP7320432B2 - Inkjet printer and method of controlling an inkjet printer - Google Patents

Description

The present invention relates to an inkjet printer having an inkjet head that ejects ultraviolet curable ink. The present invention also relates to a control method for such an inkjet printer.

Conventionally, it is equipped with an inkjet head that ejects UV curable ink toward the print medium, an ultraviolet ray irradiator that irradiates the ink ejected from the inkjet head with ultraviolet rays to cure the ink, and an inkjet head and an ultraviolet ray irradiator. Inkjet printers are widely used that include a carriage for printing and a carriage driving mechanism that reciprocates the carriage in the main scanning direction. In this inkjet printer, when the ultraviolet rays emitted from the ultraviolet irradiator are reflected by the print medium and reach the nozzles (ink ejection openings) of the inkjet head, the ink in the nozzles may harden and cause clogging.

In other words, in the case of an inkjet printer that prints on a printing medium with UV curable ink, the inkjet head nozzles are affected by the so-called stray light in which the UV rays emitted from the UV irradiator and reflected by the printing medium reach the nozzles of the inkjet head. Clogging may occur. Therefore, conventionally, in an inkjet printer that prints on a printing medium with ultraviolet curable ink, various measures have been taken to suppress clogging of the nozzles of the inkjet head caused by stray light.

For example, in the inkjet printer described in Patent Document 1, in order to reduce the amount of ultraviolet rays (stray light) that are reflected by the printing medium and reach the nozzles of the inkjet head, the optical axis of the ultraviolet rays emitted from the ultraviolet irradiator is aligned with the ink jet printer. The mounting angle of the ultraviolet irradiator is tilted so as to move away from the head. In this inkjet printer, by reducing the amount of stray light reaching the nozzles of the inkjet head, clogging of the nozzles of the inkjet head due to stray light is suppressed.

Japanese Patent Application Laid-Open No. 2004-284141

In the case of an inkjet printer that prints on a print medium with UV curable ink, as the reflectance of the print medium increases, the amount of UV rays reflected by the print medium and reaching the nozzles of the inkjet head increases, causing stray light. Due to this, clogging of nozzles of the inkjet head is likely to occur. Therefore, in an inkjet printer that prints on a printing medium with UV curable ink, even if the printing medium with the highest reflectance is generally used, the ink jet head may be damaged due to stray light. Various measures have been taken to prevent nozzle clogging.

However, even with an inkjet printer in which such measures are taken, the inkjet printer actually uses a print medium with a higher reflectance than the print medium with the highest reflectance among the print media assumed to be used. If this is the case (that is, if a print medium with a reflectance higher than expected is used), clogging of the nozzles of the inkjet head due to stray light may not be suppressed.

Therefore, an object of the present invention is to solve the problem of clogging of nozzles of an inkjet head caused by stray light in an inkjet printer that prints on a printing medium with ultraviolet curable ink even if a printing medium with a higher reflectance than expected is used. To provide an inkjet printer capable of suppressing Another object of the present invention is to solve the problem of clogging of nozzles of an inkjet head caused by stray light in an inkjet printer that prints on a printing medium with ultraviolet curable ink even if a printing medium with a higher reflectance than expected is used. An object of the present invention is to provide a control method for an inkjet printer that can suppress the

In order to solve the above-mentioned problems, the inkjet printer of the present invention includes an inkjet head formed with a plurality of nozzles for ejecting ultraviolet curable ink toward a print medium, and an inkjet head that irradiates the print medium with ultraviolet rays. An inkjet printer comprising an ultraviolet irradiator for curing ink ejected onto a print medium, a carriage on which the inkjet head and the ultraviolet irradiator are mounted, and a carriage driving mechanism for reciprocating the carriage in a main scanning direction, Equipped with a reflectance detection mechanism for detecting the reflectance of a medium and a control unit for controlling the inkjet printer, the ultraviolet irradiator includes a plurality of irradiating units separated in the main scanning direction, and is PWM-controlled to emit ultraviolet rays. The irradiator and the inkjet head are adjacent to each other in the main scanning direction, and it is possible to adjust the integrated amount of ultraviolet light emitted from the ultraviolet irradiator to the print medium during one reciprocating motion of the carriage according to the reflectance of the print medium. The control unit detects the reflectance of the print medium using the reflectance detection mechanism before printing on the print medium, and based on the detected reflectance of the print medium, the entire ultraviolet irradiator or the ultraviolet irradiator By changing the effective voltage applied to a part of the UV irradiator to change the illuminance of the ultraviolet ray radiated to the print medium from the ultraviolet irradiator, the total amount of ultraviolet ray radiated to the print medium from the ultraviolet irradiator during one reciprocating motion of the carriage. Applied to a part of the ultraviolet irradiator on the inkjet head side in the main scanning direction when changing the amount of light and lowering the illuminance of the ultraviolet ray irradiated to the print medium due to the high reflectance of the detected print medium. It is characterized by lowering the effective voltage.

In the ink jet printer of the present invention, the cumulative amount of ultraviolet light emitted from the ultraviolet irradiator to the print medium during one reciprocating motion of the carriage can be adjusted according to the reflectance of the print medium. Therefore, in the present invention, when a print medium with a higher reflectance than expected is used in an inkjet printer, it is possible to reduce the integrated amount of UV light irradiated onto the print medium from the UV irradiator during one reciprocating motion of the carriage. become. Therefore, in the present invention, even if a print medium having a reflectance higher than expected is used in an inkjet printer, the cumulative light amount of ultraviolet rays reflected by the print medium and reaching the nozzles of the inkjet head during one reciprocating motion of the carriage can be reduced. As a result, clogging of the nozzles of the inkjet head due to stray light can be suppressed.
Further, in the present invention, the inkjet printer includes a reflectance detection mechanism for detecting the reflectance of the print medium, and a control unit for controlling the inkjet printer, and the control unit detects the reflectance before printing on the print medium. A mechanism is used to detect the reflectance of the print medium, and based on the detected reflectance of the print medium, the integrated amount of UV light irradiated to the print medium from the UV irradiator during one reciprocating motion of the carriage is changed. Therefore, it is possible to automatically adjust the integrated light amount of ultraviolet light irradiated onto the print medium from the ultraviolet irradiator during one reciprocating motion of the carriage according to the reflectance of the print medium. In addition, based on the reflectance of the print medium detected by the reflectance detection mechanism, the cumulative amount of UV light irradiated onto the print medium from the UV irradiator during one reciprocating motion of the carriage is integrated according to the reflectance of the print medium. Since it is possible to adjust the amount of light with high precision, when using a print medium with a higher reflectance than expected, the ultraviolet rays that reach the nozzles of the inkjet head after being reflected by the print medium during one reciprocating motion of the carriage. It is possible to accurately reduce the integrated amount of light. Therefore, even if a print medium having a reflectance higher than expected is used, it is possible to effectively suppress clogging of the nozzles of the inkjet head caused by stray light.
Further, in the present invention, the control unit changes the illuminance of the ultraviolet rays emitted from the ultraviolet rays irradiator to the print medium, thereby increasing the integrated amount of ultraviolet rays emitted from the ultraviolet rays irradiator to the print medium during one reciprocating motion of the carriage. Since it is changed, it is possible to relatively easily change the cumulative light quantity of ultraviolet rays irradiated onto the print medium from the ultraviolet ray irradiator during one reciprocating motion of the carriage.
Further, in the present invention, the control unit changes the illuminance of the ultraviolet rays applied to the print medium by changing the effective voltage applied to the entire ultraviolet irradiator or a part of the ultraviolet irradiator. Further, in the present invention, the ultraviolet irradiator and the inkjet head are adjacent to each other in the main scanning direction, and the control section controls the movement of the ultraviolet irradiator in the main scanning direction when lowering the illuminance of the ultraviolet ray irradiated onto the print medium. lowers the effective voltage applied to a portion of the ink jet head side in . Therefore, when the reflectance of the print medium is high and the illuminance of the ultraviolet rays irradiated to the print medium is reduced, the illuminance of the ultraviolet irradiator near the inkjet head becomes low, resulting in one reciprocating motion of the carriage. It is possible to further reduce the cumulative amount of ultraviolet rays that are sometimes reflected by the print medium and reach the nozzles of the inkjet head. Therefore, even if a print medium having a reflectance higher than expected is used, clogging of the nozzles of the inkjet head due to stray light can be suppressed more effectively.

Further, in order to solve the above problems, the inkjet printer of the present invention includes an inkjet head formed with a plurality of nozzles for ejecting ultraviolet curable ink toward a printing medium, and an inkjet head that irradiates the printing medium with ultraviolet rays. An inkjet printer comprising an ultraviolet irradiator that cures ink ejected from a head onto a print medium, a carriage on which the inkjet head and the ultraviolet irradiator are mounted, and a carriage drive mechanism that reciprocates the carriage in a main scanning direction. , a reflectance detection mechanism for detecting the reflectance of the print medium, and a control unit for controlling the inkjet printer , the ultraviolet irradiator includes a plurality of irradiation units separated in the main scanning direction, and the ultraviolet irradiator The inkjet head is adjacent to the print medium in the main scanning direction, and it is possible to adjust the integrated amount of UV light irradiated to the print medium from the UV irradiator during one reciprocating motion of the carriage according to the reflectance of the print medium. , the control unit detects the reflectance of the print medium using the reflectance detection mechanism before printing on the print medium, and based on the detected reflectance of the print medium, turns off a part of the ultraviolet irradiator to turn off the ultraviolet irradiator. By changing the illuminance of the ultraviolet rays irradiated onto the printing medium from the UV irradiation device, the integrated amount of ultraviolet rays irradiated onto the printing medium from the ultraviolet irradiation device during one reciprocating movement of the carriage is changed, and the reflectance of the detected printing medium is increased . A part of the ultraviolet irradiator on the inkjet head side in the main scanning direction is turned off when the illuminance of the ultraviolet ray irradiated to the print medium is lowered .

In the ink jet printer of the present invention, the cumulative amount of ultraviolet light emitted from the ultraviolet irradiator to the print medium during one reciprocating motion of the carriage can be adjusted according to the reflectance of the print medium. Therefore, in the present invention, when a print medium with a higher reflectance than expected is used in an inkjet printer, it is possible to reduce the integrated amount of UV light irradiated onto the print medium from the UV irradiator during one reciprocating motion of the carriage. become. Therefore, in the present invention, even if a print medium having a reflectance higher than expected is used in an inkjet printer, the cumulative light amount of ultraviolet rays reflected by the print medium and reaching the nozzles of the inkjet head during one reciprocating motion of the carriage can be reduced. As a result, clogging of the nozzles of the inkjet head due to stray light can be suppressed.
Further, in the present invention, the inkjet printer includes a reflectance detection mechanism for detecting the reflectance of the print medium, and a control unit for controlling the inkjet printer, and the control unit detects the reflectance before printing on the print medium. A mechanism is used to detect the reflectance of the print medium, and based on the detected reflectance of the print medium, the integrated amount of UV light irradiated to the print medium from the UV irradiator during one reciprocating motion of the carriage is changed. Therefore, it is possible to automatically adjust the integrated light amount of ultraviolet light irradiated onto the print medium from the ultraviolet irradiator during one reciprocating motion of the carriage according to the reflectance of the print medium. In addition, based on the reflectance of the print medium detected by the reflectance detection mechanism, the cumulative amount of UV light irradiated onto the print medium from the UV irradiator during one reciprocating motion of the carriage is integrated according to the reflectance of the print medium. Since it is possible to adjust the amount of light with high precision, when using a print medium with a higher reflectance than expected, the ultraviolet rays that reach the nozzles of the inkjet head after being reflected by the print medium during one reciprocating motion of the carriage. It is possible to accurately reduce the integrated amount of light. Therefore, even if a print medium having a reflectance higher than expected is used, it is possible to effectively suppress clogging of the nozzles of the inkjet head caused by stray light.
Further, in the present invention, the control unit changes the illuminance of the ultraviolet rays emitted from the ultraviolet rays irradiator to the print medium, thereby increasing the integrated amount of ultraviolet rays emitted from the ultraviolet rays irradiator to the print medium during one reciprocating movement of the carriage. Since it is changed, it is possible to relatively easily change the cumulative light quantity of ultraviolet rays irradiated onto the print medium from the ultraviolet ray irradiator during one reciprocating motion of the carriage.
Further, in the present invention, the control unit changes the illuminance of the ultraviolet rays applied to the print medium by turning off a portion of the ultraviolet irradiator. Further, in the present invention, the ultraviolet irradiator and the inkjet head are adjacent to each other in the main scanning direction, and the control section controls the movement of the ultraviolet irradiator in the main scanning direction when lowering the illuminance of the ultraviolet ray irradiated onto the print medium. A part of the ink jet head side in is extinguished. Therefore, when the reflectance of the print medium is high and the illuminance of the ultraviolet rays irradiated to the print medium is reduced, the illuminance of the ultraviolet irradiator near the inkjet head becomes low, resulting in one reciprocating motion of the carriage. It is possible to further reduce the cumulative amount of ultraviolet rays that are sometimes reflected by the print medium and reach the nozzles of the inkjet head. Therefore, even if a print medium having a reflectance higher than expected is used, clogging of the nozzles of the inkjet head due to stray light can be suppressed more effectively.

In the present invention, the reflectance detection mechanism is an optical sensor capable of detecting the width of the print medium in the main scanning direction, the optical sensor is mounted on the carriage, and the controller controls the optical sensor before printing on the print medium. A sensor is used to detect the width of the print medium in the main scanning direction, and based on the detected width of the print medium in the main scanning direction and the reflectance of the print medium, the ultraviolet irradiator emits light to the print medium during one reciprocating motion of the carriage. It is preferable to change the integrated amount of ultraviolet light irradiated to the . With this configuration, based on the detected width of the print medium in the main scanning direction and the reflectance of the print medium, the nozzles of the inkjet head can be more effectively suppressed from clogging due to stray light. It is possible to adjust the integrated amount of ultraviolet light emitted from the ultraviolet irradiator to the print medium during one reciprocating motion.

In the present invention, the reflectance detection mechanism is preferably an ultraviolet sensor. With this configuration, it is possible to accurately detect the ultraviolet reflectance of the print medium. Therefore, it is possible to more accurately adjust the integrated amount of ultraviolet light emitted from the ultraviolet irradiator to the printing medium during one reciprocating motion of the carriage based on the detected reflectance of the printing medium. It is possible to further reduce the cumulative amount of ultraviolet rays that are reflected by the printing medium and reach the nozzles of the inkjet head during one reciprocating motion. Therefore, even if a print medium having a reflectance higher than expected is used, clogging of the nozzles of the inkjet head due to stray light can be suppressed more effectively.

Further, in order to solve the above problems, the control method for an inkjet printer of the present invention includes an inkjet head having a plurality of nozzles for ejecting ultraviolet curable ink toward a printing medium, and irradiating the printing medium with ultraviolet rays. a carriage on which the inkjet head and the ultraviolet ray irradiator are mounted; a carriage driving mechanism for reciprocating the carriage in the main scanning direction; a reflectance detection mechanism for detecting reflectance, the ultraviolet ray irradiator has a plurality of irradiation units separated in the main scanning direction, and is PWM-controlled, and the ultraviolet ray irradiator and the inkjet head are arranged in the main scanning direction. A control method for an inkjet printer adjacent to the above, wherein the reflectance of the print medium is detected using a reflectance detection mechanism before printing on the print medium, and based on the detected reflectance of the print medium, an ultraviolet irradiator is detected. By changing the effective voltage applied to the entire UV irradiator or part of the UV irradiator to change the illuminance of the ultraviolet ray radiated from the UV irradiator to the print medium, Inkjet head side of the ultraviolet irradiator in the main scanning direction when changing the integrated light amount of the irradiated ultraviolet light and decreasing the illuminance of the ultraviolet light irradiated to the print medium due to the high reflectance of the detected print medium. is characterized by lowering the effective voltage applied to a part of the

In the inkjet printer control method of the present invention, the reflectance of the print medium is detected by using the reflectance detection mechanism before printing on the print medium, and based on the detected reflectance of the print medium, during one reciprocating movement of the carriage. The cumulative amount of UV light emitted from the UV irradiator to the print medium is varied. Therefore, in the present invention, when a print medium with a higher reflectance than expected is used in an inkjet printer, it is possible to reduce the integrated amount of UV light irradiated onto the print medium from the UV irradiator during one reciprocating movement of the carriage. become. Therefore, in the present invention, even if a print medium having a reflectance higher than expected is used in an inkjet printer, the cumulative light amount of ultraviolet rays reflected by the print medium and reaching the nozzles of the inkjet head during one reciprocating motion of the carriage can be reduced. As a result, clogging of the nozzles of the inkjet head due to stray light can be suppressed.
Further, in the present invention, based on the reflectance of the print medium detected by the reflectance detection mechanism, the cumulative light amount of ultraviolet light emitted from the ultraviolet irradiator to the print medium during one reciprocating movement of the carriage is changed. Therefore, it is possible to accurately adjust the integrated amount of ultraviolet light emitted from the ultraviolet irradiator to the printing medium during one reciprocating motion of the carriage to an integrated amount of light corresponding to the reflectance of the printing medium. Therefore, in the present invention, when a print medium having a reflectance higher than expected is used, it is possible to accurately reduce the integrated light amount of ultraviolet rays that are reflected by the print medium and reach the nozzles of the inkjet head during one reciprocating motion of the carriage. As a result, even if a print medium with a reflectance higher than expected is used, clogging of the nozzles of the inkjet head due to stray light can be effectively suppressed. In addition, in the present invention, based on the reflectance of the print medium detected by the reflectance detection mechanism, the integrated amount of ultraviolet light emitted from the ultraviolet irradiator to the print medium during one reciprocating motion of the carriage is automatically adjusted. becomes possible.
In addition, in the present invention, by changing the illuminance of the ultraviolet rays emitted from the ultraviolet irradiator to the print medium, the cumulative amount of ultraviolet rays emitted from the ultraviolet irradiator to the print medium during one reciprocating motion of the carriage is changed. It is possible to relatively easily change the integrated amount of ultraviolet light emitted from the ultraviolet irradiator to the printing medium during one reciprocating motion of the carriage.
Further, in the present invention, the illuminance of the ultraviolet rays applied to the print medium is changed by changing the effective voltage applied to the entire ultraviolet irradiator or a part of the ultraviolet irradiator. Further, in the present invention, the ultraviolet irradiator and the inkjet head are adjacent to each other in the main scanning direction. reduce the effective voltage applied to a portion of Therefore, when the reflectance of the print medium is high and the illuminance of the ultraviolet rays irradiated to the print medium is reduced, the illuminance of the ultraviolet irradiator near the inkjet head becomes low, resulting in one reciprocating motion of the carriage. It is possible to further reduce the cumulative amount of ultraviolet rays that are sometimes reflected by the print medium and reach the nozzles of the inkjet head. Therefore, even if a print medium having a reflectance higher than expected is used, clogging of the nozzles of the inkjet head due to stray light can be suppressed more effectively.

Further, in order to solve the above problems, the control method for an inkjet printer of the present invention includes an inkjet head having a plurality of nozzles for ejecting ultraviolet curable ink toward a printing medium, and irradiating the printing medium with ultraviolet rays. a carriage on which the inkjet head and the ultraviolet ray irradiator are mounted; a carriage driving mechanism for reciprocating the carriage in the main scanning direction; and a reflectance detection mechanism for detecting reflectance, the ultraviolet irradiator includes a plurality of irradiation units separated in the main scanning direction, and the ultraviolet irradiator and the inkjet head are adjacent to each other in the main scanning direction. A control method for an inkjet printer, comprising detecting the reflectance of a print medium using a reflectance detection mechanism before printing on the print medium, and turning off a portion of an ultraviolet irradiator based on the detected reflectance of the print medium. By changing the illuminance of the ultraviolet rays emitted from the ultraviolet irradiator to the print medium by changing the illuminance of the ultraviolet rays emitted from the ultraviolet irradiator to the print medium during one reciprocating movement of the carriage, the integrated amount of ultraviolet light emitted from the ultraviolet irradiator to the print medium is changed, and the detected print medium intensity is changed. A part of the ultraviolet ray irradiator on the side of the inkjet head in the main scanning direction is turned off when the illuminance of the ultraviolet ray irradiated to the printing medium due to the high reflectance is lowered.

In the inkjet printer control method of the present invention, the reflectance of the print medium is detected by using the reflectance detection mechanism before printing on the print medium, and based on the detected reflectance of the print medium, during one reciprocating movement of the carriage. The cumulative amount of UV light emitted from the UV irradiator to the print medium is varied. Therefore, in the present invention, when a print medium with a higher reflectance than expected is used in an inkjet printer, it is possible to reduce the integrated amount of UV light irradiated onto the print medium from the UV irradiator during one reciprocating movement of the carriage. become. Therefore, in the present invention, even if a print medium having a reflectance higher than expected is used in an inkjet printer, the cumulative light amount of ultraviolet rays reflected by the print medium and reaching the nozzles of the inkjet head during one reciprocating motion of the carriage can be reduced. As a result, clogging of the nozzles of the inkjet head due to stray light can be suppressed.

Further, in the present invention, based on the reflectance of the print medium detected by the reflectance detection mechanism, the cumulative light amount of ultraviolet light emitted from the ultraviolet irradiator to the print medium during one reciprocating movement of the carriage is changed. Therefore, it is possible to accurately adjust the integrated amount of ultraviolet light emitted from the ultraviolet irradiator to the printing medium during one reciprocating motion of the carriage to an integrated amount of light corresponding to the reflectance of the printing medium. Therefore, in the present invention, when a print medium having a reflectance higher than expected is used, it is possible to accurately reduce the integrated light amount of ultraviolet rays that are reflected by the print medium and reach the nozzles of the inkjet head during one reciprocating motion of the carriage. As a result, even if a print medium with a reflectance higher than expected is used, clogging of the nozzles of the inkjet head due to stray light can be effectively suppressed. In addition, in the present invention, based on the reflectance of the print medium detected by the reflectance detection mechanism, the integrated amount of ultraviolet light emitted from the ultraviolet irradiator to the print medium during one reciprocating movement of the carriage is automatically adjusted. becomes possible.
In addition, in the present invention, by changing the illuminance of the ultraviolet rays emitted from the ultraviolet irradiator to the print medium, the cumulative amount of ultraviolet rays emitted from the ultraviolet irradiator to the print medium during one reciprocating motion of the carriage is changed. It is possible to relatively easily change the integrated amount of ultraviolet light emitted from the ultraviolet irradiator to the printing medium during one reciprocating motion of the carriage.
Further, in the present invention, by turning off a part of the ultraviolet irradiator, the illuminance of the ultraviolet ray irradiated to the print medium is changed. Further, in the present invention, the ultraviolet irradiator and the inkjet head are adjacent to each other in the main scanning direction. extinguish a part of Therefore, when the reflectance of the print medium is high and the illuminance of the ultraviolet rays irradiated to the print medium is reduced, the illuminance of the ultraviolet irradiator near the inkjet head becomes low, resulting in one reciprocating motion of the carriage. It is possible to further reduce the cumulative amount of ultraviolet rays that are sometimes reflected by the print medium and reach the nozzles of the inkjet head. Therefore, even if a print medium having a reflectance higher than expected is used, clogging of the nozzles of the inkjet head due to stray light can be suppressed more effectively.

As described above, according to the present invention, in an inkjet printer that prints on a printing medium with ultraviolet curable ink, even if a printing medium with a higher reflectance than expected is used, the nozzles of the inkjet head caused by stray light will not be affected. It is possible to suppress clogging.

1 is a schematic diagram for explaining the configuration of an inkjet printer according to an embodiment of the present invention; FIG. FIG. 2 is a bottom view for explaining the configuration and arrangement of the inkjet head, the ultraviolet irradiator, and the reflectance detection mechanism shown in FIG. 1;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Configuration of inkjet printer)
FIG. 1 is a schematic diagram for explaining the configuration of an inkjet printer 1 according to an embodiment of the invention. FIG. 2 is a bottom view for explaining the configuration and arrangement of the inkjet head 3, the ultraviolet irradiation device 6 and the reflectance detection mechanism 10 shown in FIG.

An inkjet printer 1 (hereinafter referred to as “printer 1”) of the present embodiment is, for example, an inkjet printer for business use, and prints on a printing medium 2 . The printing medium 2 is, for example, printing paper, cloth, resin film, or the like. The printer 1 includes an inkjet head 3 (hereinafter referred to as “head 3 ”) that ejects ultraviolet curable ink (UV ink) toward the print medium 2 . The printer 1 of this embodiment has a plurality of heads 3 .

The printer 1 also includes a table 5 on which the print medium 2 is placed, an ultraviolet ray irradiator 6 for irradiating the print medium 2 with ultraviolet rays to cure the ink ejected from the head 3 onto the print medium 2, the head 3 and A carriage 7 on which an ultraviolet irradiator 6 is mounted, a carriage driving mechanism 8 that reciprocates the carriage 7 in the main scanning direction (the Y direction in FIG. 1, etc.), a guide rail 9 that guides the carriage 7 in the main scanning direction, A reflectance detection mechanism 10 for detecting the reflectance of the print medium 2 and a control section 11 for controlling the printer 1 are provided. Further, the printer 1 has a Y bar (not shown) to which the guide rail 9 is fixed, and a vertical direction (Z direction in FIG. 1 etc.) and a sub-scanning direction (X direction in FIG. 1 etc.) orthogonal to the main scanning direction. and a Y bar moving mechanism (not shown) for moving the Y bar.

In the following description, the main scanning direction (Y direction) will be referred to as the "horizontal direction" and the sub-scanning direction (X direction) will be referred to as the "front-to-back direction." The printer 1 may be provided with a table moving mechanism for moving the table 5 in the front-rear direction (sub-scanning direction) instead of the Y-bar moving mechanism. Further, instead of the Y-bar moving mechanism and the table 5, the printer 1 may include a platen on which the printing medium 2 is placed during printing and a medium feeding mechanism for feeding the printing medium 2 in the sub-scanning direction. .

The carriage 7 is arranged above the table 5 . The carriage drive mechanism 8 includes, for example, two pulleys, a belt that is stretched over the two pulleys and partially fixed to the carriage 7, and a motor that rotates the pulleys. A motor of the carriage drive mechanism 8 is electrically connected to the controller 11 . A plurality of heads 3 are mounted on a carriage 7 so as to be adjacent to each other in the horizontal direction, for example. The head 3 ejects ink toward the upper surface of the print medium 2 placed on the table 5 . That is, the head 3 ejects ink downward.

A plurality of nozzle rows 14 are formed on the lower surface of the head 3 to eject ultraviolet curable ink. The nozzle row 14 is composed of a plurality of nozzles arranged in the front-rear direction. That is, the head 3 is formed with a plurality of nozzles for ejecting ultraviolet curable ink. The plurality of nozzle rows 14 are arranged adjacent to each other in the left-right direction. The head 3 includes a piezoelectric element (piezo element) that ejects ink from nozzles. The piezoelectric element is electrically connected to the controller 11 .

The ultraviolet irradiators 6 are mounted on the carriage 7 on both sides of the plurality of heads 3 in the left-right direction. That is, the carriage 7 is equipped with two ultraviolet irradiators 6 , and the ultraviolet irradiators 6 are arranged on both sides of the plurality of heads 3 in the left-right direction. Moreover, the ultraviolet irradiator 6 and the head 3 are adjacent to each other in the horizontal direction. The ultraviolet irradiation device 6 is arranged at the same position as the head 3 in the front-rear direction.

The ultraviolet irradiator 6 emits ultraviolet rays toward the print medium 2 arranged below the ultraviolet irradiator 6 . The ultraviolet irradiator 6 is composed of, for example, a plurality of light emitting elements and a substrate on which the plurality of light emitting elements are mounted. The light-emitting element is, for example, a UVLED chip that emits ultraviolet rays. The substrate is formed, for example, in a rectangular shape, and is arranged so that the thickness direction and the vertical direction of the substrate are aligned, and the long side direction and the front-back direction of the substrate are aligned.

Moreover, the ultraviolet irradiator 6 is composed of a plurality of irradiating portions 6b and 6c that are separated in the left-right direction. The ultraviolet irradiation device 6 of this embodiment is composed of two irradiation units 6b and 6c. The irradiation unit 6b is arranged on the side of the head 3 in the left-right direction. That is, in the ultraviolet irradiation device 6 arranged on the right side, the irradiation section 6b is arranged on the left side and the irradiation section 6c is arranged on the right side. Further, in the ultraviolet irradiation device 6 arranged on the left side, the irradiation section 6b is arranged on the right side and the irradiation section 6c is arranged on the left side.

The ultraviolet irradiator 6 is electrically connected to the controller 11 . The ultraviolet irradiation device 6 of this embodiment is PWM (Pulse Width Modulation) controlled. The illuminance (intensity) of the ultraviolet rays emitted from the ultraviolet ray irradiator 6 to the print medium 2 varies depending on the effective voltage applied to the ultraviolet ray irradiator 6 . Moreover, in this embodiment, the irradiation section 6b and the irradiation section 6c can be individually controlled. That is, the control unit 11 can individually control the irradiation unit 6b and the irradiation unit 6c.

The reflectance detection mechanism 10 is an optical sensor capable of detecting the width of the print medium 2 in the horizontal direction. Also, the reflectance detection mechanism 10 is a reflective optical sensor having a light emitting portion 15 and a light receiving portion 16 . A reflectance detection mechanism 10 is mounted on the carriage 7 . Specifically, the reflectance detection mechanism 10 is mounted on the carriage 7 so that the light emitting surface of the light emitting unit 15 and the light receiving surface of the light receiving unit 16 face downward. The reflectance detection mechanism 10 is arranged between the head 3 and the ultraviolet irradiation device 6 in the left-right direction. In the following description, the reflectance detection mechanism 10 is referred to as an "optical sensor 10".

The optical sensor 10 is electrically connected to the controller 11 . That is, the light emitting section 15 and the light receiving section 16 are electrically connected to the control section 11 . The light emitting unit 15 emits visible light. The light receiving unit 16 receives visible light emitted from the light emitting unit 15 and reflected by the printing medium 2 or the table 5 .

When the carriage 7 reciprocates in the horizontal direction while emitting light from the light emitting unit 15, the control unit 11 controls the reflection of the print medium 2 based on the amount of light received by the light receiving unit 16 of the light reflected by the print medium 2. detect rate. Further, when the carriage 7 is reciprocated in the horizontal direction while emitting light from the light emitting unit 15 , the control unit 11 determines the amount of light reflected by the printing medium 2 received by the light receiving unit 16 and the amount of light reflected by the table 5 . Based on the difference between the amount of light received by the light receiving unit 16 and the amount of light received by the light receiving unit 16, the left and right end surfaces of the print medium 2 are detected, and based on the detected left and right end surfaces of the print medium 2, the left and right direction of the print medium 2 is detected. width.

In this embodiment, the control unit 11 detects the reflectance of the print medium 2 using the optical sensor 10 before printing on the print medium 2 . In addition, the control unit 11 detects the width of the print medium 2 in the horizontal direction using the optical sensor 10 before the print medium 2 is printed. That is, before printing on the print medium 2, the control unit 11 causes the carriage 7 to reciprocate in the left-right direction while emitting light from the light emitting unit 15, thereby determining the reflectance of the print medium 2 and the width of the print medium 2 in the left-right direction. to detect.

Based on the detected reflectance of the print medium 2, the control unit 11 determines the cumulative amount of ultraviolet light emitted from the ultraviolet irradiator 6 to the print medium 2 during one reciprocating motion of the carriage 7 (ultraviolet illuminance and irradiation time). ) is changed. More specifically, based on the detected reflectance of the print medium 2 and the width of the print medium 2 in the horizontal direction, the control unit 11 irradiates the print medium 2 from the ultraviolet irradiator 6 during one reciprocating motion of the carriage 7 . change the integrated amount of UV light emitted. From the start of printing on one print medium 2 to the end of printing, the cumulative light amount of ultraviolet rays irradiated from the ultraviolet irradiator 6 to the print medium 2 during one reciprocating motion of the carriage 7 is constant.

In this embodiment, the control unit 11 changes the illuminance of the ultraviolet rays emitted from the ultraviolet irradiator 6 to the print medium 2, thereby controlling the amount of ultraviolet rays emitted from the ultraviolet irradiator 6 to the print medium 2 during one reciprocating motion of the carriage 7. change the integrated amount of light. Specifically, when the moving speed of the carriage 7 is constant, the product of the detected reflectance of the print medium 2, the detected width of the print medium 2 in the horizontal direction, and the illuminance of the ultraviolet rays irradiated to the print medium 2 is The control unit 11 controls the ultraviolet irradiator 6 to change the illuminance of the ultraviolet ray emitted from the ultraviolet irradiator 6 to the printing medium 2 so as to be substantially constant.

Further, in this embodiment, the control unit 11 controls the ultraviolet irradiator 6 to change the effective voltage applied to a part of the ultraviolet irradiator 6, thereby changing the illuminance of the ultraviolet ray irradiated to the print medium 2. . Further, the control unit 11 reduces the effective voltage applied to the irradiation unit 6b when reducing the illuminance of the ultraviolet rays applied to the print medium 2. FIG. That is, the control unit 11 reduces the effective voltage applied to a portion of the ultraviolet ray irradiator 6 on the side of the head 3 in the left-right direction when lowering the illuminance of the ultraviolet rays applied to the print medium 2 .

As described above, in the printer 1 , the integrated light amount of ultraviolet rays irradiated onto the print medium 2 from the ultraviolet irradiator 6 during one reciprocating movement of the carriage 7 can be adjusted according to the reflectance of the print medium 2 . More specifically, in the printer 1, according to the reflectance of the print medium 2 and the width of the print medium 2 in the left-right direction, the ultraviolet rays emitted from the ultraviolet irradiator 6 to the print medium 2 during one reciprocation of the carriage 7 is adjustable.

(Main effects of this form)
As described above, in the present embodiment, the control unit 11 detects the reflectance of the print medium 2 using the optical sensor 10 before printing on the print medium 2, and based on the detected reflectance of the print medium 2, , the integrated amount of ultraviolet light emitted from the ultraviolet ray irradiator 6 to the print medium 2 during one reciprocating motion of the carriage 7 is changed. Therefore, in the present embodiment, when the printer 1 uses the print medium 2 having a reflectance higher than expected, the cumulative light amount of ultraviolet rays irradiated from the ultraviolet irradiator 6 to the print medium 2 during one reciprocating movement of the carriage 7 is can be reduced. Therefore, in this embodiment, even if the printer 1 uses a print medium 2 having a higher reflectance than expected, the cumulative light amount of ultraviolet rays reflected by the print medium 2 and reaching the nozzles of the head 3 during one reciprocating motion of the carriage 7 is can be reduced, and as a result, clogging of the nozzles of the head 3 caused by stray light can be suppressed.

Further, in this embodiment, based on the reflectance of the print medium 2 detected by the optical sensor 10, the integrated light amount of the ultraviolet light emitted from the ultraviolet irradiator 6 to the print medium 2 during one reciprocating movement of the carriage 7 is changed. Therefore, it is possible to accurately adjust the integrated amount of ultraviolet light emitted from the ultraviolet irradiator 6 to the printing medium 2 during one reciprocating motion of the carriage 7 to an integrated amount of light corresponding to the reflectance of the printing medium 2 . . Therefore, in the present embodiment, when the printer 1 uses the print medium 2 having a reflectance higher than expected, the total amount of ultraviolet rays reflected by the print medium 2 and reaching the nozzles of the head 3 during one reciprocating motion of the carriage 7 is It is possible to accurately reduce the amount of light, and as a result, even if a print medium 2 with a higher reflectance than expected is used, it is possible to effectively suppress clogging of the nozzles of the head 3 due to stray light. become.

Furthermore, in the present embodiment, the control unit 11 detects the lateral width of the print medium 2 in addition to the reflectance of the print medium 2 before printing on the print medium 2, and detects the reflectance of the print medium 2 and the print medium. Based on the width of the medium 2 in the left-right direction, the integrated light amount of the ultraviolet light emitted from the ultraviolet irradiator 6 to the printing medium 2 during one reciprocating motion of the carriage 7 is changed. In order to more effectively suppress clogging, it is possible to adjust the integrated light amount of ultraviolet rays irradiated from the ultraviolet irradiator 6 to the printing medium 2 during one reciprocating motion of the carriage 7 .

Further, in this embodiment, based on the reflectance of the print medium 2 detected by the optical sensor 10, the integrated amount of ultraviolet light emitted from the ultraviolet irradiator 6 to the print medium 2 during one reciprocating movement of the carriage 7 is automatically adjusted. can be adjusted accordingly.

In this embodiment, the control unit 11 changes the illuminance of the ultraviolet rays emitted from the ultraviolet irradiator 6 to the print medium 2, thereby controlling the amount of ultraviolet rays emitted from the ultraviolet irradiator 6 to the print medium 2 during one reciprocating motion of the carriage 7. is changing the integrated amount of light. Therefore, in this embodiment, for example, by changing the moving speed of the carriage 7, compared to the case of changing the cumulative light amount of ultraviolet light irradiated to the print medium 2 from the ultraviolet irradiator 6 during one reciprocating motion of the carriage 7, Therefore, it is possible to relatively easily change the cumulative amount of ultraviolet light emitted from the ultraviolet irradiator 6 to the printing medium 2 during one reciprocating motion of the carriage 7 .

In this embodiment, the control unit 11 reduces the effective voltage applied to the irradiation unit 6b, which is a part of the ultraviolet irradiation device 6 on the side of the head 3 in the horizontal direction, when reducing the illuminance of the ultraviolet rays irradiated to the print medium 2. lowering. Therefore, in this embodiment, when the reflectance of the print medium 2 is high and the illuminance of the ultraviolet rays irradiated to the print medium 2 is decreased, the illuminance of the portion of the ultraviolet irradiator 6 near the head 3 is lowered. Therefore, in this embodiment, it is possible to further reduce the integrated light amount of ultraviolet rays that are reflected by the printing medium 2 and reach the nozzles of the head 3 during one reciprocating motion of the carriage 7. As a result, the reflectance is higher than expected. Even if a high print medium 2 is used, clogging of the nozzles of the head 3 caused by stray light can be suppressed more effectively.

(Modified Example of Lighting Control of Ultraviolet Irradiator)
In the embodiment described above, the control section 11 may reduce the effective voltage applied to the irradiation section 6c when reducing the illuminance of the ultraviolet rays with which the print medium 2 is irradiated. Further, in the above-described embodiment, the control unit 11 may change the illuminance of the ultraviolet rays applied to the print medium 2 by changing the effective voltage applied to the entire ultraviolet irradiator 6 . In this case, the ultraviolet irradiation device 6 does not have to be divided into the two irradiation sections 6b and 6c.

In the embodiment described above, the control unit 11 may change the illuminance of the ultraviolet rays with which the printing medium 2 is irradiated by turning off part of the ultraviolet irradiator 6 . In this case, the control unit 11 may turn off the irradiation unit 6c when reducing the illuminance of the ultraviolet rays irradiated to the print medium 2, but preferably turns off the irradiation unit 6b. That is, when the illuminance of the ultraviolet rays irradiated to the print medium 2 is lowered, the control section 11 preferably turns off a portion of the ultraviolet irradiator 6 on the side of the head 3 in the left-right direction.

In this case, when the reflectance of the print medium 2 is high and the illuminance of the ultraviolet rays irradiated to the print medium 2 is lowered, the illuminance of the portion of the ultraviolet irradiator 6 near the head 3 becomes low, so that the carriage It is possible to further reduce the cumulative light quantity of ultraviolet light reflected by the printing medium 2 and reaching the nozzles of the head 3 during one reciprocating motion of the head 7 . Therefore, even if a print medium 2 having a reflectance higher than expected is used, it is possible to more effectively suppress clogging of the nozzles of the head 3 due to stray light.

In the form described above, the UV irradiator 6 may be current controlled. In this case, the control unit 11 changes the illuminance of the ultraviolet rays with which the print medium 2 is irradiated, for example, by changing the current supplied to a part of the ultraviolet irradiator 6 . In this case, the control unit 11 may reduce the current supplied to the irradiation unit 6c when reducing the illuminance of the ultraviolet rays irradiated to the print medium 2, but it is possible to reduce the current supplied to the irradiation unit 6b. preferable. Further, the control unit 11 may change the illuminance of the ultraviolet rays irradiated to the print medium 2 by changing the current supplied to the entire ultraviolet irradiation device 6 .

(Modified example of reflectance detection mechanism)
In the form mentioned above, the reflectance detection mechanism 10 may be an ultraviolet sensor. In this case, it is possible to accurately detect the reflectance of ultraviolet rays on the print medium 2. Therefore, the integrated light amount of ultraviolet rays irradiated to the print medium 2 from the ultraviolet irradiator 6 during one reciprocating movement of the carriage 7 is It is possible to perform more accurate adjustment based on the detected reflectance of the print medium 2 . Therefore, it is possible to further reduce the integrated amount of ultraviolet light that is reflected by the print medium 2 and reaches the nozzles of the head 3 during one reciprocating motion of the carriage 7 . As a result, even if a print medium 2 having a reflectance higher than expected is used, it is possible to effectively suppress clogging of the nozzles of the head 3 due to stray light.

(Other embodiments)
The embodiment described above is an example of the preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention.

In the embodiment described above, the control unit 11 controls the motor of the carriage drive mechanism 8 to change the moving speed of the carriage 7, so that the print medium 2 is irradiated from the ultraviolet ray irradiator 6 during one reciprocating motion of the carriage 7. The cumulative amount of UV light may be changed. Further, in the embodiment described above, the control unit 11 changes the illuminance of the ultraviolet ray emitted from the ultraviolet ray irradiator 6 to the print medium 2 and the movement speed of the carriage 7 so that the ultraviolet ray irradiator 6 during one reciprocating movement of the carriage 7 It is also possible to change the integrated amount of ultraviolet light irradiated onto the printing medium 2 from the above.

In the embodiment described above, a reflectance detection mechanism for detecting the reflectance of the print medium 2 and a medium width detection mechanism for detecting the width of the print medium 2 in the horizontal direction may be separately provided. In this case, the reflectance detection mechanism does not have to be mounted on the carriage 7 . Further, in the embodiment described above, the optical sensor 10 does not have to detect the lateral width of the print medium 2 . In this case, the control unit 11 changes the integrated amount of UV light applied to the print medium 2 from the UV irradiator 6 during one reciprocating motion of the carriage 7 based only on the detected reflectance of the print medium 2 .

In the form described above, the printer 1 does not have to include the optical sensor 10 . In this case, the operator of the printer 1 manually adjusts the cumulative amount of UV light irradiated onto the print medium 2 from the UV irradiator 6 during one reciprocation of the carriage 7 according to the reflectance of the print medium 2 . For example, a plurality of ultraviolet irradiation modes are preset according to the reflectance of the print medium 2, and the operator of the printer 1 confirms the reflectance of the print medium 2 and, according to the reflectance of the print medium 2, A predetermined ultraviolet irradiation mode is selected and set.

Even in this case, when a print medium 2 having a reflectance higher than expected is used, it is possible to reduce the integrated light amount of ultraviolet rays irradiated to the print medium 2 from the ultraviolet irradiator 6 during one reciprocating motion of the carriage 7. Therefore, even if a print medium 2 having a reflectance higher than expected is used, the cumulative light amount of ultraviolet rays reflected by the print medium 2 and reaching the nozzles of the head 3 during one reciprocating motion of the carriage 7 can be reduced. becomes possible. Therefore, it is possible to suppress clogging of the nozzles of the head 3 due to stray light. For example, when the nozzles of the head 3 are clogged, the operator of the printer 1 can reduce the integrated amount of ultraviolet light emitted from the ultraviolet irradiator 6 to the print medium 2 during one reciprocating motion of the carriage 7. , a predetermined ultraviolet irradiation mode may be selected and set.

In the form mentioned above, the ultraviolet ray irradiator 6 may be configured by three or more irradiating sections separated in the left-right direction. Moreover, in the above-described embodiment, the number of the ultraviolet irradiators 6 mounted on the carriage 7 may be one. Furthermore, in the embodiment described above, the number of heads 3 included in the printer 1 may be one.

1 Printer (inkjet printer)
2 print medium 3 head (inkjet head)
6 UV irradiator 7 Carriage 8 Carriage drive mechanism 10 Optical sensor (reflectance detection mechanism)
11 control unit Y main scanning direction

Claims (6)

An inkjet head formed with a plurality of nozzles for ejecting ultraviolet curable ink toward a print medium, and ultraviolet irradiation for curing the ink ejected from the inkjet head onto the print medium by irradiating the print medium with ultraviolet rays. an inkjet printer, a carriage on which the inkjet head and the ultraviolet irradiation device are mounted, and a carriage driving mechanism for reciprocating the carriage in a main scanning direction,
A reflectance detection mechanism for detecting the reflectance of the print medium, and a control unit for controlling the inkjet printer,
The ultraviolet irradiator includes a plurality of irradiating units separated in the main scanning direction and is PWM controlled,
The ultraviolet irradiator and the inkjet head are adjacent to each other in the main scanning direction,
According to the reflectance of the print medium, an integrated amount of ultraviolet light irradiated from the ultraviolet irradiator to the print medium during one reciprocating movement of the carriage can be adjusted,
The control unit detects the reflectance of the print medium using the reflectance detection mechanism before printing the print medium, and detects the reflectance of the print medium based on the detected reflectance of the print medium. By changing the effective voltage applied to a part of the ultraviolet irradiator to change the illuminance of the ultraviolet ray emitted from the ultraviolet irradiator to the print medium, the printing is performed from the ultraviolet irradiator during one reciprocating movement of the carriage. Main scanning of the ultraviolet ray irradiator when changing the integrated light quantity of the ultraviolet rays irradiated to the medium and lowering the illuminance of the ultraviolet rays irradiated to the print medium because the reflectance of the detected print medium is high. An inkjet printer, characterized in that the effective voltage applied to a portion of the inkjet head side in a direction is lowered. An inkjet head formed with a plurality of nozzles for ejecting ultraviolet curable ink toward a print medium, and ultraviolet irradiation for curing the ink ejected from the inkjet head onto the print medium by irradiating the print medium with ultraviolet rays. an inkjet printer, a carriage on which the inkjet head and the ultraviolet irradiation device are mounted, and a carriage driving mechanism for reciprocating the carriage in a main scanning direction,
A reflectance detection mechanism for detecting the reflectance of the print medium, and a control unit for controlling the inkjet printer,
The ultraviolet irradiator includes a plurality of irradiation units separated in the main scanning direction,
The ultraviolet irradiator and the inkjet head are adjacent to each other in the main scanning direction,
According to the reflectance of the print medium, an integrated amount of ultraviolet light irradiated from the ultraviolet irradiator to the print medium during one reciprocating movement of the carriage can be adjusted,
The control unit detects the reflectance of the print medium using the reflectance detection mechanism before printing on the print medium, and turns off part of the ultraviolet irradiator based on the detected reflectance of the print medium. and change the illuminance of the ultraviolet rays irradiated from the ultraviolet irradiation device to the printing medium, thereby changing the integrated light quantity of the ultraviolet rays irradiated onto the printing medium from the ultraviolet irradiation device during one reciprocating movement of the carriage. and extinguishing a portion of the ultraviolet irradiator on the ink jet head side in the main scanning direction when the illuminance of the ultraviolet rays irradiated to the print medium is reduced due to the detected reflectivity of the print medium becoming high. An inkjet printer characterized by: The reflectance detection mechanism is an optical sensor capable of detecting the width of the print medium in the main scanning direction,
The optical sensor is mounted on the carriage,
The control unit uses the optical sensor to detect the width of the print medium in the main scanning direction before printing the print medium, and detects the detected width of the print medium in the main scanning direction and the reflection of the print medium. 3. An ink jet printer according to claim 1 , wherein the integrated light amount of ultraviolet rays irradiated from said ultraviolet ray irradiator to said printing medium during one reciprocating movement of said carriage is changed based on the rate. 4. The inkjet printer according to claim 1 , wherein the reflectance detection mechanism is an ultraviolet sensor. An inkjet head formed with a plurality of nozzles for ejecting ultraviolet curable ink toward a print medium, and ultraviolet irradiation for curing the ink ejected from the inkjet head onto the print medium by irradiating the print medium with ultraviolet rays. a device, a carriage on which the inkjet head and the ultraviolet irradiator are mounted, a carriage drive mechanism for reciprocating the carriage in the main scanning direction, and a reflectance detection mechanism for detecting the reflectance of the print medium. A control method for an inkjet printer , wherein the ultraviolet ray irradiator includes a plurality of irradiating units separated in the main scanning direction, PWM-controlled, and the ultraviolet ray irradiator and the inkjet head are adjacent to each other in the main scanning direction. and
The reflectance of the print medium is detected using the reflectance detection mechanism before printing on the print medium, and the entire ultraviolet irradiator or a portion of the ultraviolet irradiator is detected based on the detected reflectance of the print medium. By changing the effective voltage applied to the ultraviolet irradiator to change the illuminance of the ultraviolet ray irradiated to the print medium from the ultraviolet irradiator, the print medium is irradiated from the ultraviolet irradiator during one reciprocating movement of the carriage In addition to changing the integrated light quantity of ultraviolet light, when the reflectance of the detected print medium is high and the illuminance of the ultraviolet light irradiated to the print medium is reduced, the inkjet head in the main scanning direction of the ultraviolet irradiator A control method for an ink jet printer, characterized by lowering the effective voltage applied to a portion of the side. An inkjet head formed with a plurality of nozzles for ejecting ultraviolet curable ink toward a print medium, and ultraviolet irradiation for curing the ink ejected from the inkjet head onto the print medium by irradiating the print medium with ultraviolet rays. a device, a carriage on which the inkjet head and the ultraviolet irradiator are mounted, a carriage drive mechanism for reciprocating the carriage in the main scanning direction, and a reflectance detection mechanism for detecting the reflectance of the print medium. wherein the ultraviolet ray irradiator comprises a plurality of irradiating units separated in the main scanning direction, and the ultraviolet ray irradiator and the inkjet head are adjacent to each other in the main scanning direction.
Before printing on the print medium, the reflectance of the print medium is detected using the reflectance detection mechanism, and based on the detected reflectance of the print medium, part of the ultraviolet irradiator is extinguished to irradiate the ultraviolet light. By changing the illuminance of the ultraviolet ray irradiated from the device to the print medium, the integrated light amount of the ultraviolet ray irradiated from the ultraviolet ray irradiator to the print medium is changed during one reciprocating motion of the carriage, and the detected print An ink jet printer characterized by turning off a portion of the ultraviolet ray irradiator on the side of the ink jet head in the main scanning direction when the reflectance of the medium is high and the illuminance of the ultraviolet ray irradiated to the print medium is reduced. control method.

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