JP4631393B2 - Inkjet printer - Google Patents

Description

  The present invention relates to an inkjet printer, and more particularly, to an inkjet printer including a white ink recording head that discharges white ink and a colored ink recording head that discharges colored ink.

  In recent years, the ink jet recording method can create images more easily and cheaply than the gravure printing method, and thus has been applied to various printing fields such as special printing such as photography, various printing, marking, and color filters. In particular, in the ink jet recording system, an ink jet recording system recording head that ejects and controls fine dots, ink that has improved color reproduction range, durability, ejection suitability, etc., and ink absorbability, colorant coloring, and surface gloss It is also possible to obtain an image comparable to a silver salt photograph by combining with special paper that has been dramatically improved.

  However, on the other hand, it is known that an ink containing a pigment precipitates over time even with the improved ink as described above. When the pigment is precipitated in this manner, an image having a desired density cannot be obtained. Therefore, an ink jet printer that can disperse the pigment once precipitated in the ink has been developed.

For example, an inkjet printer described in Patent Document 1 includes a recording head that ejects ink onto a recording medium, a carriage that mounts the recording head and reciprocates in the main scanning direction, and ink that is mounted on the carriage and supplied to the recording head. An ink tank for storage. A moving body made of a spherical body is accommodated in the ink tank, and the moving body reciprocates in the ink tank by the reciprocating movement of the carriage to disperse the precipitated pigment.
JP 09-309212 A

  However, even if such an ink jet printer can disperse the pigment precipitated in the ink tank in the ink, the ink supply path such as the inside of the recording head and the communication pipe that connects the recording head and the ink tank is used. The pigment precipitated inside cannot be dispersed in the ink. In particular, pigments with a relatively large specific gravity, such as titanium oxide, contained in white ink are more likely to accumulate in the ink supply path due to their specific gravity than pigments with a low specific gravity that are pigments for colored ink. It is difficult to remove. The pigment accumulated in the ink supply path causes an ink ejection failure, and the ink ejection failure has a problem that the image quality is deteriorated.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet printer that can appropriately remove a pigment deposited in an ink supply path and obtain a high-quality recorded image.

In order to solve the above-described problem, in the invention described in claim 1, it is an ultraviolet curable ink that is cured by being irradiated with ultraviolet rays, and the white ink supplied through the ink supply path is supplied to the discharge port. A recording head for white ink discharged from the recording medium to the recording medium;
A recording head for colored ink , which is an ultraviolet curable ink that is cured by being irradiated with ultraviolet rays, and that discharges the colored ink supplied through an ink supply path from the discharge port to the recording medium;
Ink in the white ink recording head and the colored ink recording head by applying a predetermined suction force to the ink supply path and the ink ejection port of the white ink recording head and the colored ink recording head. A suction device for applying a negative pressure to the supply path and the ink ejection port;
The suction force applied to the ink supply path and the ink discharge port of the white ink recording head is more than the suction force applied to the ink supply path and the ink discharge port of the colored ink recording head. By increasing the negative pressure, the negative pressure applied to the ink supply path of the white ink recording head and to the ink discharge port is negatively applied to the ink supply path of the colored ink recording head and the ink discharge port. A controller that controls the suction device to be greater than the pressure;
An ultraviolet irradiation device for irradiating the ink landed on the recording medium with ultraviolet rays;
A UV label affixed in the vicinity of the ink ejection opening and discolored in accordance with the amount of ultraviolet rays irradiated;
A sensor capable of detecting the color of the UV label,
The control unit drives the suction device when the color of the UV label detected by the sensor becomes a predetermined color .

As described above, according to the first aspect of the present invention, a pigment having a specific gravity larger than that of the other pigment contained in the white ink is difficult to remove outside the ink supply path communicating with the ejection port due to the specific gravity. However, by applying a suction force larger than the suction force applied to the discharge port of the colored ink recording head to the discharge port of the white ink recording head, the discharge port of the white ink recording head Applying a negative pressure larger than the negative pressure applied to the discharge port of the colored ink recording head , thereby sucking and removing foreign matters such as pigment accumulated in the ink supply path communicating with the discharge port of the white ink recording head. Can do. For this reason, it is possible to prevent the ink from being clogged in the ink supply path which causes ink ejection failure.
Further, by using the ultraviolet curable ink, it is possible to prevent the recorded image from bleeding on the recording medium even if the recording medium has no ink absorbability.
In addition, since the controller drives the suction device when the color of the UV label becomes a predetermined color, it is possible to easily and appropriately determine the timing for driving the suction device.

The invention according to claim 2, in the ink jet printer according to claim 1, wherein the control unit, up to reach the negative pressure applied to the ink supply path and the discharge port of the ink of the white ink recording head 0 The suction device is controlled such that the maximum ultimate negative pressure applied to the ink supply path of the colored ink recording head and to the ink ejection port is less than 0.05 Mpa. .

Thus, according to the second aspect of the present invention, the maximum ultimate negative pressure applied to the ink supply path of the white ink recording head and the ink discharge port is 0.05 Mpa or more, and the ink of the colored ink recording head is used. The suction unit is controlled by the control unit so that the maximum negative pressure applied to the supply path and the ink ejection port is less than 0.05 MPa.

According to a third aspect of the present invention, in the ink jet printer according to the first aspect, a supply path blocking mechanism arranged in the middle of the ink supply path for supplying ink to the white ink recording head is configured to block the ink supply path. Prepared,
When the suction unit applies a suction force to the ink supply path of the white ink recording head and to the ink discharge port by the suction device, the control unit applies pressure before and after the supply path blocking mechanism inside the ink supply path. The supply path blocking mechanism and the suction device are controlled so as to release the blocking of the ink supply path by the supply path blocking mechanism in a state where a difference is generated.

Thus, according to the third aspect of the present invention, when the suction device applies a suction force to the ink supply path of the white ink recording head and to the ink discharge port, the supply path blocking mechanism is provided inside the ink supply path. Since the ink supply path is blocked by the supply path blocking mechanism in a state where a pressure difference is generated between the front and the back, an impact pressure is generated in the ink supply path of the white ink, and the ink discharged thereby Etc., foreign matter such as ink accumulated in the ink supply path of the recording head for white ink and the ink discharge port can be removed.

According to a fourth aspect of the present invention, in the ink jet printer according to the third aspect, the control unit applies a suction force applied to the ink supply path and the ink discharge port of the white ink recording head. The suction device is controlled so as to be larger than the suction force applied to the ink supply path of the color ink recording head and to the ink ejection port.

Thus, according to the fourth aspect of the present invention, the white ink recording head is further provided with a suction force greater than the suction force applied to the discharge port of the colored ink recording head. Foreign matters such as pigments accumulated in the ink supply path communicating with the ejection port of the ink recording head can be reliably removed by suction. For this reason, it is possible to prevent the ink from being clogged in the ink supply path which causes ink ejection failure.

According to a fifth aspect of the present invention, in the inkjet printer according to any one of the first to fourth aspects, the control unit drives the suction device before image recording is started. It is a feature.

As described above, according to the fifth aspect of the present invention, the pigment accumulated in the ink supply path communicating with the discharge port of the white ink recording head is appropriately removed by the suction device before the image recording is started. Can do. Therefore, it is possible to prevent ink from being clogged in the ink supply path at the start of image recording.

According to a sixth aspect of the present invention, in the ink jet printer according to any one of the first to fifth aspects, the recording medium is a transparent or opaque resin film.

Thus, according to the sixth aspect of the present invention, even when a transparent or opaque resin film having no ink absorbability is used as the recording medium, the recorded image is blurred on the recording medium. Can be prevented.

Invention according to claim 7, in the ink jet printer according to any one of claims 1 to 6, wherein the white ink contains a white pigment as the colorant, the content of the white pigment is the It is characterized by being 1 to 50% by mass of the whole white ink composition.

Thus, according to the seventh aspect of the invention, image recording is performed using white ink having a white pigment content of 1 to 50% by mass of the entire white ink composition. However, foreign matters such as ink can be appropriately removed.

The invention according to claim 8 is the inkjet printer according to any one of claims 1 to 6 , wherein the white ink contains a white pigment as a colorant, and the content of the white pigment is The white ink composition is 2 to 30% by mass.

As described above, according to the invention described in claim 8 , image recording is performed using the white ink whose white pigment content is 2 to 30% by mass of the entire white ink composition. However, foreign matters such as ink can be appropriately removed.

According to the first aspect of the present invention, the negative pressure applied to the ink supply path and the ink discharge port of the white ink recording head is changed to the negative pressure applied to the ink supply path and the ink discharge port of the colored ink recording head. Larger than. As a result, even when white ink containing a white pigment with a high specific gravity is used for image recording, foreign matter such as ink is properly removed, and deterioration in image quality due to ink ejection failure is prevented, and high-quality recorded images There is an effect that can be obtained.
In addition, since the timing for driving the suction device can be easily and appropriately determined, it is possible to prevent deterioration in image quality due to ink ejection failure and to obtain a high-quality recorded image. .
Moreover, since it is possible to prevent the recorded image from bleeding on the recording medium, it is possible to obtain a high-quality recorded image in which occurrence of ink bleeding is prevented.

According to the second aspect of the present invention, the maximum ultimate negative pressure applied to the ink supply path of the white ink recording head and the ink ejection port is set to 0.05 Mpa or more, and the ink supply path of the colored ink recording head The maximum negative pressure applied to the ink ejection port is set to less than 0.05 MPa. As a result, even when white ink containing a white pigment with a high specific gravity is used for image recording, foreign matter such as ink is properly removed, and deterioration in image quality due to ink ejection failure is prevented, and high-quality recorded images There is an effect that can be obtained.

According to the third aspect of the present invention, after the pressure difference is generated before and after the supply path blocking mechanism in the ink supply path of the white ink recording head, the blocking of the ink supply path is released and the impact pressure is generated. . Therefore, negative pressure applied to the ink supply path of the white ink recording head and the ink discharge port is applied to the ink supply path of the colored ink recording head and the ink discharge port without increasing the suction force of the suction device. It can be larger than the negative pressure. As a result, even when white ink containing a white pigment with a high specific gravity is used for image recording, foreign matter such as ink is properly removed, and deterioration in image quality due to ink ejection failure is prevented, and high-quality recorded images There is an effect that can be obtained.

According to the fourth aspect of the present invention, the suction force applied by the suction device is applied to the ink supply path of the white ink recording head and to the ink discharge port. Because it is larger than what is applied to the ink ejection port, even when white ink containing a white pigment with a heavy specific gravity is used for image recording, foreign matters such as ink are more reliably removed, resulting in defective ink ejection. There is an effect that it is possible to obtain a high-quality recorded image while preventing deterioration of the image quality.

According to the fifth aspect of the present invention, since the suction device is driven before image recording is started, it is possible to prevent a decrease in image quality due to ink ejection failure and obtain a high-quality recorded image. There is an effect that can be.

According to the invention described in claim 6 , even when a transparent or opaque resin film having no ink absorbability is used as the recording medium, it is possible to prevent a recorded image from bleeding on the recording medium. As a result, it is possible to obtain a high-quality recorded image in which the occurrence of ink bleeding is prevented.

According to the seventh aspect of the present invention, even when image recording is performed using white ink having a white pigment content of 1 to 50% by mass of the entire white ink composition, the ink supply path or the ink discharge port is provided. Foreign matter such as attached white pigment can be appropriately removed. For this reason, it is possible to prevent a decrease in image quality due to ink ejection failure, and it is possible to obtain a high-quality recorded image.

According to the eighth aspect of the present invention, even when image recording is performed using white ink having a white pigment content of 2 to 30% by mass of the entire white ink composition, the ink supply path or the ink discharge port is provided. Foreign matter such as attached white pigment can be appropriately removed. For this reason, it is possible to prevent a decrease in image quality due to ink ejection failure, and it is possible to obtain a high-quality recorded image.

  Hereinafter, a first embodiment of an inkjet printer according to the present invention will be described with reference to FIGS. 1 and 2. However, the scope of the invention is not limited to the illustrated examples.

  First, the ink jet printer 1 according to the present invention shown in FIG. 1 is a serial type ink jet printer. The ink jet printer 1 is provided with a long casing (not shown) that constitutes an outer frame thereof, and a central portion in the longitudinal direction of the casing (hereinafter simply referred to as a main scanning direction) is a recording area. Has been. One side of the recording area in the main scanning direction is a home position area, and the other side is a maintenance area.

  The recording area is provided with a platen 3 that supports the recording medium 2 from a non-recording surface and holds the recording surface of the recording medium 2 in a substantially horizontal state. A recording medium transport device 4 (see FIG. 2) is provided at both ends of the platen 3 in a direction orthogonal to the main scanning direction (hereinafter simply referred to as the sub-scanning direction). The recording medium 2 is conveyed in the sub-scanning direction while supporting the two non-recording surfaces. The recording medium 2 is a transparent resin film.

  A guide rail 7 extending along the main scanning direction is provided in the housing. A carriage 8 is supported on the guide rail 7, and the carriage 8 is guided by the guide rail 7 by a carriage driving device 16 (see FIG. 2) and can reciprocate in the main scanning direction. The carriage 8 is provided with white ink recording heads 9 and 9 for discharging white ink to the recording medium 2 and colored ink recording heads 10 and 10 for discharging colored ink along the main scanning direction. The white ink recording heads 9 are disposed at both ends in the main scanning direction. These white ink recording heads 9, 9 and colored ink recording heads 10, 10,... Are moved by the carriage 8 along the main scanning direction from the home position area to the maintenance area. On the side of the white ink recording heads 9, 9 and the colored ink recording heads 10, 10,... Facing the recording medium 2, an ejection port (not shown) for ejecting ink is disposed along the sub-scanning direction. Has been.

  In the colored ink recording heads 10 and 10 of the present embodiment, a colored ink tank that stores any one of four colors of black (K), yellow (Y), magenta (M), and cyan (C) is stored. Are connected to each other via colored ink supply pipes 6, 6,..., And the colored ink recording heads 10, 10,... Have ink colors stored in the ink tanks 5, 5,. Corresponding color ink is ejected. White ink tanks 11 and 11 for storing white ink (W) are communicated with the white ink recording heads 9 and 9 via white ink supply pipes 12 and 12. 9 is adapted to eject white ink. Here, the inside of the white ink recording heads 9, 9 and the white ink supply pipes 12, 12 communicating with the ejection ports of the white ink recording heads 9, 9 are connected to the white ink tanks 11, 11 and the ejection ports. The ink supply path communicates with each other. Similarly, the colored ink recording heads 10, 10,... And the colored ink supply pipes 6, 6,... Communicating with the discharge ports of the colored ink recording heads 10, 10,. 5 is an ink supply path that communicates with the ejection ports. The white ink tanks 11, 11 and the colored ink tanks 5, 5... Are provided with a stirrer (not shown) that stirs the stored ink. , 11 and the colored ink tanks 5, 5,... Are agitated to make the concentration of each stored ink uniform.

  Further, ultraviolet irradiation devices 15 and 15 each having an ultraviolet light source (not shown) are attached to both ends of the carriage 8 in the main scanning direction, and the ultraviolet irradiation devices 15 and 15 apply ultraviolet light to ink landed on the recording medium 2. It comes to irradiate. As the ultraviolet light source, a high pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, a black light, a hot cathode tube, a cold cathode tube, and an LED (Light Emitting Diode) can be applied.

  Here, in the maintenance area, a maintenance unit 20 for performing maintenance on the white ink recording heads 9 and 9 and the colored ink recording heads 10, 10... Is provided. The maintenance unit 20 covers the ink discharge ports of the white ink recording heads 9 and 9 and the colored ink recording heads 10, 10,... A plurality of suction caps 21, 21... Are provided for sucking each ink from an ink supply path communicating with the surface and the ejection port. The suction caps 21, 21 are provided with a suction device 25 as a negative pressure generating mechanism that sucks ink or the like by applying a negative pressure to the ink supply path and the ink discharge port in each of the recording heads 9, 10. When the suction caps 21, 21,... Cover the respective discharge surfaces, the suction device 25 creates a negative pressure inside the suction caps 21, 21,. Each ink or the like is sucked from an ink supply path communicating with the outlet.

  In the present embodiment, the suction device 25 includes, for example, a cylinder pump or a tube pump. Here, the suction force of the ink or the like by the suction device 25 in the present embodiment is such that when the atmospheric pressure is 0.1 MPa and the vacuum pressure is 0 MPa, the colored ink recording heads 10, 10. Is preferably about 0.05 Mpa, and the maximum negative pressure when sucking white ink from the white ink recording heads 9 and 9 is 0.05 Mpa or more and less than 0 Mpa. It is preferable. Here, the maximum ultimate negative pressure is a maximum ultimate value of the negative pressure generated when the suction device 25 is driven.

  Note that the suction operation by the suction device 25 may be performed by continuously operating a pump or the like, or may be intermittently operated, or may be operated with strength, and then step by step. Suction may be performed so as to reach a maximum negative pressure that is a typical target pressure. Further, the configuration of the suction device 25 is not limited to the one exemplified here, and any configuration can be applied as long as it can secure a suction force sufficient to suck the colored ink and the white ink.

  By the suction operation of the suction device 25 as described above, the pressure inside the suction caps 21, 21... Covering the discharge surfaces of the color ink recording heads 10, 10 in order to suck colored ink is set to −0.05 Mpa. It has come to be. Further, the pressure inside the suction cap 21 that covers the ejection surface of the white ink recording heads 9 and 9 in order to remove white ink, white pigment and other foreign matters by suction is set to −0.1 Mpa by the suction device 25. It is like that. With such a pressure value, each ink filled in the ink supply path communicating with each ejection port of the white ink recording heads 9 and 9 and the colored ink recording heads 10, 10. In particular, the white ink recording heads 9 and 9 are configured to suck and remove white pigment and other foreign matters accumulated in the discharge port and the ink supply path communicating with the discharge port.

  The maintenance unit 20 also includes a cleaning blade 22 for wiping off each ink adhering to each of the ejection surfaces, and an ink that receives each ink ejected from the white ink recording heads 9 and 9 and the colored ink recording heads 10 and 10. A receiver 23 and a lifting device (not shown) that drives the maintenance unit 20 to move up and down are provided.

  Next, in the home position area, a moisturizing unit 30 for moisturizing the ejection surfaces of the white ink recording heads 9, 9 and the colored ink recording heads 10, 10,. The moisturizing unit 30 includes six moisturizing caps 31, 31..., And the moisturizing caps 31, 31... Have white ink recording heads 9, 9 and colored ink recording heads 10, 10. In the standby state, the ink in each ejection port is moisturized by covering each ejection surface.

  In the present embodiment, near the ejection surfaces of the white ink recording heads 9, 9 and the colored ink recording heads 10, 10,. It is pasted. This UV label has a characteristic of changing from white to red as the amount of irradiated ultraviolet light increases. A detection device 45 (see FIG. 2) capable of detecting the color of the UV label is provided at any position between the home position area and the maintenance area. The detection device 45 is provided with a reflection sensor (not shown) for measuring the reflectance of light and a red LED (not shown), and the red light emitted from the red LED is reflected by the UV label and reflected. Light is received by a reflection sensor and the reflectance is measured.

Next, the control device in the present embodiment will be described with reference to FIG.
The control device includes, for example, a CPU 40, a RAM 41, and a ROM 42, and has a control unit 43 that develops a processing program recorded in the ROM 42 onto the RAM 41 and executes the processing program by the CPU 40.

  The control unit 43 is connected to an input unit 44 including a scanner for inputting image information, a keyboard for inputting image recording conditions, and the like. The control unit 43 receives predetermined information input from the input unit 44 and the above-described information. Based on the processing program, the operations of the recording medium transport device 4, the white ink recording heads 9, 9, the colored ink recording heads 10, 10,..., The ultraviolet irradiation device 15, the carriage driving device 16, the suction device 25, and the like are controlled. It is supposed to be.

  In addition, a detection device 45 is connected to the control unit 43, and the control unit 43 determines the degree of discoloration of the UV label based on detection information input from the detection device 45. When it is determined that the UV label has changed to a predetermined color change degree, the control unit 43 controls the carriage driving device 16 and the maintenance unit 20 to automatically perform a maintenance operation.

  Further, the control unit 43 controls the carriage driving device 16 and the maintenance unit 20 before image recording is started when predetermined information is input from the input unit 44, and the white ink recording head 9 is automatically controlled. , 9 maintenance operations are performed.

Next, “ink” used in the present embodiment will be described.
The ink used in the present embodiment is an ultraviolet curable ink that is cured by irradiation with ultraviolet rays, and contains at least a polymerizable compound (including a known polymerizable compound), a photoinitiator, and a color material as main components. It is a waste.

  The ultraviolet curable ink is roughly classified into a polymerizable compound, a radical polymerization type ultraviolet curable ink containing a radical polymerizable compound, and a cationic polymerization type ultraviolet curable ink containing a cationic polymerizable compound. Both types of inks can be applied as inks used in this embodiment, and hybrid inks in which radical polymerization type ultraviolet curable inks and cationic polymerization type ultraviolet curable inks are combined are used in this embodiment. It may be applied as a prepared ink. Here, as compared with radical polymerization type ultraviolet curable ink, cationic polymerization type ultraviolet curable ink has high sensitivity to ultraviolet rays and less inhibition of polymerization reaction due to oxygen, so that the illuminance required for curing the ink can be reduced. For this reason, in this embodiment, a cationic polymerization type ultraviolet curable ink is used as the ink.

  In this embodiment, the white ink can use a white pigment as a colorant. The white pigment is not particularly limited as long as it makes the ink composition white, and usually white pigments used in this field can be applied.

  As such a white pigment, for example, a white inorganic pigment, a white organic pigment, or white hollow polymer fine particles can be used. Examples of white inorganic pigments include alkaline earth metal sulfates such as barium sulfate, alkaline earth metal carbonates such as calcium carbonate, silicas such as finely divided silicic acid, and synthetic silicates, calcium silicate, alumina, alumina Hydrates, titanium oxide, zinc oxide, talc, clay and the like can be mentioned.

  Examples of the white organic pigment include organic compound salts disclosed in JP-A No. 11-129613 and alkylene bismelamine derivatives disclosed in JP-A Nos. 11-14365 and 2001-234093. Specific examples of white organic pigments include Shigenox OWP, Shigenox OWPL, Shigenox FWP, Shigenox FWG, Shigenox UL, and Shigenox U (all of these are trade names manufactured by Hackol Chemical).

  Examples of the white hollow polymer fine particles include fine particles showing thermoplasticity substantially made of an organic polymer disclosed in US Pat. No. 4,089,800.

  In the present invention, the above-described white pigment may be used alone, or two or more white pigments may be used in combination.

Of the white pigments described above, titanium oxide is particularly known as a white pigment having favorable hiding properties, colorability, and dispersed particle diameter, and the white ink used in this embodiment has a specific gravity of 4.20 g / cm ³ . Titanium oxide is included as the main white pigment. Since this titanium oxide has a higher specific gravity than the pigment contained in the ink such as black (K), yellow (Y), magenta (M), cyan (C), etc., the titanium oxide precipitates in the ink in a short time. It is like that.

  In this embodiment, the white pigment is contained in the range of 1 to 50% by mass, preferably 2 to 30% by mass of the entire ink composition. When the content of the white pigment is less than this, a sufficient concealing property cannot be obtained. On the other hand, when the content is more than this, the ejectability from the ejection ports of the white ink recording heads 9 and 9 is poor. This may cause the discharge port to become clogged.

  The cationic polymerization type ultraviolet curable ink has a property of accumulating ultraviolet energy, so that the ink is liable to thicken when irradiated with ultraviolet rays. Therefore, by monitoring the degree of discoloration of a UV label that has the property of accumulating without releasing the ultraviolet energy once taken in, it is possible to accurately grasp the degree of accumulation of ultraviolet light in the cationic polymerization type ultraviolet curable ink. It has become.

  As the recording medium 2 used in the present embodiment, a transparent or opaque non-absorbent resin film used for so-called soft packaging can be applied. Specific resin types of resin film include polyethylene terephthalate, polyester, polyolefin, polyamide, polyesteramide, polyether, polyimide, polyamideimide, polystyrene, polycarbonate, poly-ρ-phenylene sulfide, polyether ester, polyvinyl chloride , Poly (meth) acrylic acid ester, polyethylene, polypropylene, nylon and the like are applicable, and further, copolymers of these resins, mixtures of these resins, and those obtained by crosslinking these resins are also applicable. Above all, as the type of resin of the resin film, one of stretched polyethylene terephthalate, polystyrene, polypropylene, and nylon is selected because of the transparency, dimensional stability, rigidity, environmental load, cost, etc. of the resin film. Preferably, a resin film having a thickness of 2 to 1000 μm (preferably 20 to 150 μm) is used. Moreover, you may perform surface treatments, such as a corona discharge process and an easily bonding process, on the surface of the support body of resin films.

  Next, the operation of the inkjet printer 1 according to this embodiment will be described.

  When the user sets the recording medium 2 in the inkjet printer 1 and turns on the power of the inkjet printer 1, the ultraviolet light source emits light.

  When predetermined information is input from the input unit 44 to the control unit 43, the control unit 43 controls the recording medium transport device 4 in the sub-scanning direction while the ultraviolet light source emits light. Transport to. Here, the recording medium conveyance device 4 repeats conveyance and conveyance stop in order, and conveys the recording medium 2 intermittently.

  When the intermittent transport is stopped, the control unit 43 controls the white ink recording heads 9 and 9, the colored ink recording heads 10, 10..., And the carriage driving device 16, so that the ink is directed toward a predetermined position of the recording medium 2. To discharge. At this time, the ultraviolet irradiation devices 15 and 15 move together with the carriage 8 as the carriage 8 moves, so that the ink landed on the recording medium 2 is cured by the ultraviolet rays emitted from the ultraviolet light source. Thereby, an image is recorded on the recording medium 2. As described above, by using the ultraviolet curable ink, it is possible to prevent the recorded image from bleeding on the recording medium 2 even in the recording medium 2 used in the present embodiment having no ink absorbability.

  The control unit 43 according to the present embodiment is configured such that when predetermined information is input from the input unit 44 before the start of the image recording operation, other predetermined information is input from the input unit 44 as appropriate, and the UV label has a predetermined degree of discoloration. , When the carriage drive device 16 is controlled, the suction caps 21, 21... Of the maintenance unit 20, the white ink recording heads 9 and 9, and the colored ink recording heads 10, 10. The carriage 8 is moved to a position where the two face each other.

  When the carriage 8 moves to the above position, the control unit 43 controls the maintenance unit 20 so that the suction caps 21, 21,..., The white ink recording heads 9, 9, and the colored ink recording heads 10, 10,.・ Closely contact each discharge surface. In this state, the control unit 43 operates the suction device 25 so that the inside of the suction caps 21, 21. By this negative pressure, a suction force is applied to each discharge surface and each discharge port, and ink or the like is sucked from an ink supply path communicating with each discharge surface and each discharge port. In particular, with respect to the white ink recording heads 9 and 9, white pigment and other foreign matters accumulated in the ink supply path communicating with the discharge port and the discharge port are removed by suction.

  In particular, in this embodiment, titanium oxide, which is the main pigment of white ink, is difficult to remove outside the ink supply path communicating with the discharge ports of the white ink recording heads 9 and 9 due to its specific gravity. A suction force greater than the suction force applied to the ejection ports of the colored ink recording heads 10, 10,... Is applied to the ejection ports of the white ink recording heads 9, 9. Therefore, titanium oxide and other foreign matters deposited on the ink supply path communicating with the ejection ports of the white ink recording heads 9 and 9 can be appropriately removed. Thereby, it is possible to prevent the ink from being clogged in the ink supply path of the white ink recording heads 9 and 9.

  Further, the white ink having a non-uniform ink density in the ink supply path can be removed by suction with the suction force. In this embodiment, each ink stored in the white ink tanks 11 and 11 and the colored ink tanks 5, 5... Is made uniform in concentration by a stirring device. Therefore, the ink jet printer 1 according to this embodiment can make the density of each ink newly filled in the ink supply path with the above-described suction removal uniform.

  Further, at the start of the image recording, that is, when predetermined information is input from the input unit 44, the white ink having a non-uniform ink density in the ink supply path may be removed by suction with the suction force. Therefore, the ink jet printer 1 according to this embodiment can make the ink density in the ink supply path uniform at the start of the image.

  As described above, according to the ink jet printer 1 of the present embodiment, a transparent or opaque resin film having no ink absorbability is used as the recording medium 2 by using ultraviolet curable ink. In addition, since it is possible to prevent the recorded image from bleeding on the recording medium 2, it is possible to obtain a high-quality recorded image in which occurrence of ink bleeding is prevented.

  In addition, the ink supply path of the white ink recording heads 9 and 9 can be prevented from being clogged, and the ink density in the ink supply path can be made uniform. There is an effect that it is possible to obtain a high-quality recorded image in which the occurrence of variations is prevented.

  Furthermore, since the ink density in the ink supply path of the white ink recording heads 9 and 9 can be made uniform at the start of image recording, high quality that prevents the occurrence of variations in ink density from the start of image recording. An effect that a recorded image can be obtained.

  In the present embodiment, the control unit 43 is configured to perform maintenance when predetermined information is input from the input unit 44. However, the present embodiment is not limited to this, and for example, white ink is added to the inkjet printer 1. The ink jet printer 1 may be configured to perform the above-mentioned maintenance when a timer for measuring the inactive time of the recording heads 9 and 9 is provided and the elapse of a predetermined time is detected. Alternatively, the above-described maintenance may be performed immediately after the power of the inkjet printer 1 is turned on.

  Further, the inkjet printer 1 according to the present embodiment can perform front printing and back printing. For example, in the case of performing image recording on a transparent recording medium 2, the surface printing is performed by ejecting a background color ink over the entire surface of the recording medium 2, and then drying or curing the background color ink. This is a printing method in which ink for forming an image is formed so as to be superimposed on the formed portion. Since this printing method can make it difficult to transmit light to the portion where the image is formed, it is possible to make the image stand out. Further, the above-mentioned reverse printing is a portion where, when image recording is performed on a transparent recording medium 2, ink for forming an image is ejected to a predetermined area of the recording medium 2, and then the ink for forming the image is dried or cured. This is a printing method in which ink of a background color is ejected on top of each other. In this printing method, the image is formed on the back side of the transparent recording medium 4 on which the ink is ejected. Therefore, in addition to the effect of making the image stand out, the durability against scratching of the image can be maintained.

  Since the inkjet printer 1 according to the present embodiment uses white ink as a background color, it is possible to make an image formed with colored ink stand out more effectively than an image with another color as a background. There is an effect that can be.

  In addition, it is needless to say that the present invention is not limited to the above embodiment and can be modified as appropriate.

  Next, a second embodiment of the ink jet printer according to the present invention will be described with reference to FIG. The second embodiment differs from the first embodiment only in the configuration of a negative pressure generating mechanism that sucks ink or the like by applying a negative pressure to the ink supply path of the recording head for white ink and the ink ejection port. Therefore, in the following, the configuration of the negative pressure generating mechanism will be described in particular.

  The ink jet printer according to the present embodiment is a serial head type ink jet printer as in the first embodiment. As shown in FIG. 3, yellow (Y), magenta (M), cyan (C), black (K ..) Is mounted on the recording medium P. The carriage 21 is mounted. White ink recording heads 9 and 9 for discharging white ink (W) to the recording medium 2 are disposed on both ends of the main scanning direction on the carriage. The carriage 21 reciprocates in the main scanning direction X along the guide rail by a drive mechanism (not shown).

  As in the first embodiment, the color ink recording heads 10 and 10 of the present embodiment include four color inks of black (K), yellow (Y), magenta (M), and cyan (C). Color ink tanks 5, 5... For storing any one color are communicated with each other via colored ink supply pipes 6, 6..., And white ink (W The white ink tanks 11 and 11 are stored in communication with each other via the white ink supply pipes 12 and 12. The white ink recording heads 9 and 9 and the white ink supply pipes 12 and 12 that communicate with the ejection ports of the white ink recording heads 9 and 9 communicate the white ink tanks 11 and 11 with the ejection ports. This is an ink supply path. Similarly, the colored ink recording heads 10, 10,... And the colored ink supply pipes 6, 6,... Communicating with the discharge ports of the colored ink recording heads 10, 10,. 5 is an ink supply path that communicates with the ejection ports.

  In the middle of the ink supply pipes 12 and 12 serving as ink supply paths connecting the white ink tanks 11 and 11 and the white ink recording heads 9 and 9, and in the vicinity of the white ink tanks 11 and 11, the ink supply pipe 12 is provided. , 12 is provided as an on-off valve 50 as a supply path blocking mechanism. The on-off valve 50 is an electromagnetic valve provided with a solenoid (not shown) as a drive source, for example, and the valve is opened and closed by driving the solenoid. The configuration of the supply path blocking mechanism that blocks the ink supply path is not limited to this, and various valves having other structures or other various mechanisms can be used. Further, the position where the on-off valve 50 as the supply path blocking mechanism is provided is not limited to that shown in the present embodiment, and the ink supply path connecting the white ink tank and the white ink recording head is blocked halfway. It only has to be.

  As in the first embodiment, the outer end of the image recording area where image recording is performed is a maintenance area. In the maintenance area D, the white ink recording heads 9 and 9 and the colored ink recording head 10 are used. , 10... Is provided with a maintenance unit 20. As in the first embodiment, the maintenance unit 20 includes the ink ejection openings of the white ink recording heads 9 and 9 and the color ink recording heads 10, 10. And a plurality of suction caps 21, 21... For sucking each ink from an ink supply path communicating with the ejection surface and the ejection port. The suction caps 21, 21 are connected via a tube 24 to a suction device 51 that sucks ink or the like by applying a negative pressure to the ink supply path and the ink discharge port in each of the recording heads 9, 10. When the suction caps 21, 21... Cover the respective discharge surfaces, the suction device 51 applies negative pressure to the inside of the suction caps 21, 21. Each ink is sucked and removed from the path. As the suction device 51, the same device as in the first embodiment can be applied. However, the suction device 51 has a maximum reached negative pressure when sucking white ink from the white ink recording heads 9 and 9 and a maximum reached negative pressure when sucking colored inks from the colored ink recording heads 10, 10. The equivalent is sufficient.

  In the present embodiment, the suction device 51 and the on-off valve 50 serving as the supply path blocking mechanism negatively sucks ink or the like adhering to the inside of the ink supply path and the ink discharge port in each of the recording heads 9 and 10. A pressure generating mechanism is configured.

  In addition, the ink jet printer according to the present embodiment includes a control unit (not shown) for controlling each unit of the apparatus and an input unit (not shown) for performing various settings by the user, as in the first embodiment. .

  In particular, in the present embodiment, when performing maintenance of the white ink recording heads 9 and 9 and the colored ink recording heads 10, 10..., The control unit closes the on-off valve 50 and supplies ink before starting the maintenance operation. The flow of ink in the tubes 12 and 12 is blocked. Then, the control unit shuts off the ink supply path of the white ink in this way, and then operates the suction device 51 to suck the air in the ink supply pipes 12 and 12. When air is sucked by the suction device 51, the inside of the ink supply pipes 12, 12 closer to the white ink recording heads 9, 9 than the opening / closing valve 50 is depressurized, and the white ink tank 11, An internal pressure difference is generated between the ink supply pipes 12 and 12 closer to 11 and the ink supply pipes 12 and 12 closer to the white ink recording heads 9 and 9 than the on-off valve 50. Then, the control unit opens the on-off valve 50 when the pressure difference inside the ink supply pipes 12, 12 becomes a certain level or more. As a result, the colored ink recording heads 10, 10,... Are only sucked by the suction device 51, while the white ink recording heads 9, 9 are opened by opening the on-off valve 50, whereby the ink supply pipe 12 is opened. , 12 is opened, and an impact pressure is generated. As a result, the negative pressure in the ink supply path of the white ink recording heads 9, 10 and the ink discharge port is less than the negative pressure in the ink supply path of the colored ink recording heads 10, 10. The white ink recording heads 9 and 9 attract ink more strongly than the colored ink recording heads 10, 10... To remove precipitates such as titanium oxide and other foreign matters as white pigments. It has become.

  Since other configurations are the same as those of the first embodiment, the same portions are denoted by the same reference numerals, and the description thereof is omitted.

  Next, the operation of the ink jet printer in this embodiment will be described.

  When predetermined information is input from the input unit before the start of the image recording operation, when other predetermined information is input from the input unit 44 as appropriate, or when the control unit determines that the UV label has changed to a predetermined degree of discoloration Further, the control unit controls the carriage driving device so that the suction caps 21, 21... Of the maintenance unit 20 face the white ink recording heads 9 and 9 and the colored ink recording heads 10, 10. The carriage 8 is moved to the position.

  At this time, the control unit closes the on-off valve 50 and shuts off the ink supply pipes 12 and 12 connecting the white ink tanks 11 and 11 and the white ink recording heads 9 and 9 in the middle thereof.

  Next, when the carriage 8 moves to a predetermined position, the control unit 43 controls the maintenance unit 20 so that the suction caps 21, 21..., The white ink recording heads 9, 9 and the colored ink recording heads 10, 10. Contact each ejection surface of 10. In this state, the control unit operates the suction device 51 to make the inside of the suction caps 21, 21. By this negative pressure, a suction force is applied to each discharge surface and each discharge port, and ink or the like is sucked from an ink supply path communicating with each discharge surface and each discharge port. The ink supply pipes 12, 12 communicating with the white ink recording heads 9, 9 are decompressed in accordance with the suction operation of the suction device 51. When a certain pressure reduction state is reached, the control unit opens the on-off valve 50 while operating the suction device 51 and applies an impact pressure to the ink supply pipes 12 and 12 communicating with the white ink recording heads 9 and 9. Cause it to occur. As a result, the suction device 51 applies the ink supply path and the ink discharge port of the white ink recording heads 9 and 10 to the ink supply path and the ink discharge port of the colored ink recording heads 10, 10. The negative pressure at the ink supply path of the white ink recording heads 9 and 9 and at the ink ejection port is applied to the colored ink recording heads 10, 10. The pressure is greater than the negative pressure at the ink discharge port, and precipitates such as ink and titanium oxide accumulated in the ink supply path of the white ink recording heads 9 and 9 and the ink discharge port are removed by suction.

  When foreign matters such as ink accumulated in the ink supply paths of the recording heads 9 and 10 and the ink ejection openings are removed and the state suitable for image recording is restored, the user sets the recording medium 2 to the ink jet printer 1. Then, the power of the inkjet printer 1 is turned on.

  When predetermined information is input from the input unit to the control unit, the control unit conveys the recording medium 2 in the sub-scanning direction while the ultraviolet light source emits light. Then, the control unit discharges predetermined ink from the white ink recording heads 9 and 9 and the colored ink recording heads 10, 10... To the recording medium 2, and irradiates the ink landed on the recording medium 2 with ultraviolet rays from an ultraviolet light source. Let As a result, the ink is cured and fixed on the recording medium 2 and an image is recorded.

  In particular, in the present embodiment, an open / close valve is provided in the ink supply path of the white ink recording heads 9 and 9, and the ink supply pipes 12 and 12 are shut off in the middle of the suction operation to perform the suction operation. 12 and 12, and using the impact pressure generated when the on-off valve is opened, the colored ink recording heads 10, 10. A negative pressure greater than the negative pressure applied to the ink supply path and the ejection port is applied. For this reason, even when the suction force itself applied by the suction device 51 is not different between the white ink recording heads 9 and 9 and the colored ink recording heads 10, 10..., The white ink recording heads 9 and 9. It is possible to appropriately remove foreign matters such as ink and white pigment accumulated in the ink supply path communicating with the discharge port. Accordingly, even when white ink containing a pigment such as titanium oxide having a high specific gravity is used for image recording, the ink supply path of the white ink recording heads 9 and 9 can be prevented from being clogged.

  In the present embodiment, the suction force applied by the suction device 51 is not different between the white ink recording heads 9, 9 and the colored ink recording heads 10, 10,. The suction force of the white ink recording heads 9 and 9 may be larger than that of the colored ink recording heads 10 and. In this case, in combination with the impact pressure, foreign matters such as ink accumulated in the ink supply path communicating with the ejection openings of the white ink recording heads 9 and 9 can be appropriately removed more reliably and strongly.

  Further, the negative pressure applied to the ink supply pipe may be increased by reducing the diameter of the white ink supply pipe. In this case, the diameter of the ink supply pipe must be a thickness that does not hinder the flow of white ink.

  Moreover, it is the same as that of 1st embodiment that this invention is not restricted to this Embodiment.

1 is a schematic front view illustrating a configuration of a first embodiment of an inkjet printer according to the present invention. 1 is a block diagram illustrating a configuration of an embodiment of an inkjet printer according to the present invention. It is a schematic front view which shows the structure of 2nd embodiment of the inkjet printer by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Recording medium 9 White ink recording head 10 Colored ink recording head 15 Ultraviolet irradiation device 21 Suction cap 25 Suction device

Claims (8)

A recording head for white ink , which is an ultraviolet curable ink that is cured by being irradiated with ultraviolet rays , and discharges white ink supplied via an ink supply path from a discharge port to a recording medium;
A recording head for colored ink , which is an ultraviolet curable ink that is cured by being irradiated with ultraviolet rays, and that discharges the colored ink supplied through an ink supply path from the discharge port to the recording medium;
Ink in the white ink recording head and the colored ink recording head by applying a predetermined suction force to the ink supply path and the ink ejection port of the white ink recording head and the colored ink recording head. A suction device for applying a negative pressure to the supply path and the ink ejection port;
The suction force applied to the ink supply path and the ink discharge port of the white ink recording head is more than the suction force applied to the ink supply path and the ink discharge port of the colored ink recording head. By increasing the negative pressure, the negative pressure applied to the ink supply path of the white ink recording head and to the ink discharge port is negatively applied to the ink supply path of the colored ink recording head and the ink discharge port. A controller that controls the suction device to be greater than the pressure;
An ultraviolet irradiation device for irradiating the ink landed on the recording medium with ultraviolet rays;
A UV label affixed in the vicinity of the ink ejection opening and discolored in accordance with the amount of ultraviolet rays irradiated;
A sensor capable of detecting the color of the UV label,
The ink jet printer , wherein the controller drives the suction device when the color of the UV label detected by the sensor becomes a predetermined color . The control unit has a maximum ultimate negative pressure applied to the ink supply path of the white ink recording head and the ink ejection port of 0.05 Mpa or more, and the ink supply path of the colored ink recording head includes: The inkjet printer according to claim 1 , wherein the suction device is controlled so that a maximum ultimate negative pressure applied to the ink ejection port is less than 0.05 MPa. A supply path blocking mechanism arranged in the middle of the ink supply path for supplying ink to the white ink recording head and blocking the ink supply path;
When the suction unit applies a suction force to the ink supply path of the white ink recording head and to the ink discharge port by the suction device, the control unit applies pressure before and after the supply path blocking mechanism inside the ink supply path. 2. The ink jet printer according to claim 1, wherein the supply path blocking mechanism and the suction device are controlled so as to release the blocking of the ink supply path by the supply path blocking mechanism in a state where a difference is generated. The controller applies a suction force applied to the ink supply path of the white ink recording head and to the ink ejection port to the ink supply path of the colored ink recording head and the ink ejection port. The inkjet printer according to claim 3 , wherein the suction device is controlled to be larger than a suction force to be performed. The ink jet printer according to any one of claims 1 to 4 , wherein the control unit drives the suction device before image recording is started. 6. The ink jet printer according to claim 1, wherein the recording medium is a transparent or opaque resin film. The said white ink contains a white pigment as a coloring agent, The content rate of the said white pigment is 1-50 mass% of the said whole white ink composition, The any one of Claims 1-6 characterized by the above-mentioned. The inkjet printer according to one item. The said white ink contains a white pigment as a coloring agent, The content rate of the said white pigment is 2-30 mass% of the said whole white ink composition, The any one of Claims 1-6 characterized by the above-mentioned. The inkjet printer according to one item.

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