JP2005066990A - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent incomplete ink ejection due to thickening of ink in a sub-ink tank. <P>SOLUTION: A sub-ink tank 10 mounted on a carriage 6 storing ink to be ejected is provided with a Peltier unit 31, or the like, in order to sustain the ink at such a temperature as moisture in the ink does not evaporate easily thus preventing viscosity of ink from increasing due to evaporation of moisture in the ink. Consequently, incomplete ink ejection due to thickening of ink stored in the sub-ink tank 10 is prevented and an inkjet printer capable of obtaining a high quality recording image is provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ink jet printer, and more particularly to an ink jet printer in which ink is supplied from a sub ink tank to a recording head.

  2. Description of the Related Art Conventionally, there is known an ink jet printer that forms an image on a recording medium by supplying ink from an ink tank that stores ink to a recording head via a sub ink tank, and discharging the supplied ink from an ejection port of the recording head. (For example, Patent Document 1).

Some ink jet printers have a sub ink tank mounted on a carriage together with a recording head. In the sub ink tank, air is usually stored together with ink.
JP 2002-301826 A

  However, if the sub ink tank contains air, the water in the ink may evaporate. In such a case, the ink viscosity is increased, and there is a risk that the ink is clogged in the above-described ejection port. This ink clogging causes ink ejection failure, and there is a problem that a high-quality recorded image cannot always be obtained.

  Accordingly, an object of the present invention is to effectively prevent evaporation of moisture in the ink even if air is contained in the sub ink tank, thereby preventing ejection failure due to an increase in ink viscosity and high quality. It is an object of the present invention to provide an ink jet printer capable of obtaining the recorded image.

In order to solve the above-described problem, in the first aspect of the present invention, a recording head provided with an ejection port for ejecting ink to a recording medium, and a sub for storing the ink supplied to the recording head. In an inkjet printer comprising an ink tank,
A cooling device for maintaining the ink stored in the sub ink tank at a predetermined set temperature is provided.

  As described above, according to the first aspect of the present invention, it is assumed that the cooling device for maintaining the ink stored in the sub ink tank at a predetermined set temperature is provided, so that air is contained in the sub ink tank. In addition, the ink is maintained at a temperature at which the water in the ink hardly evaporates by the cooling device.

According to a second aspect of the present invention, in the ink jet printer according to the first aspect, at least one of a control unit that controls the cooling device, an amount of ink stored in the sub ink tank, and an environmental temperature around the ink tank. And a temperature input unit for setting the ink stored in the sub ink tank to an arbitrary temperature in the range of −10 ° C. to 30 ° C., and
The control unit controls the cooling device according to a detection result of the detection device, and maintains the temperature set by the temperature input unit.

  Thus, according to the second aspect of the invention, when the cooling device operates at a constant output, the ink may be excessively cooled as the ink is consumed. It cannot be maintained at a temperature that is difficult to evaporate. In the same case, the temperature of the ink stored in the sub ink tank may change depending on the ambient temperature around the sub ink tank, and the ink cannot be maintained at a temperature at which the water in the ink hardly evaporates. Therefore, by changing the output of the cooling device according to the detection result of the detection device, the ink is maintained at a temperature at which the moisture in the ink hardly evaporates regardless of the ink amount or the environmental temperature.

  According to a third aspect of the present invention, in the ink jet printer according to the first or second aspect, the cooling device includes at least one of a Peltier element and a cooling fan.

  Thus, according to the third aspect of the present invention, the ink stored in the sub ink tank is maintained at a temperature at which moisture in the ink is difficult to evaporate by the cooling device including at least one of the Peltier element and the cooling fan. Is done.

The invention according to claim 4 is the inkjet printer according to any one of claims 1 to 3,
A heating device for heating the ink supplied to the recording head to a predetermined temperature;
The ink has a viscosity at 30 ° C. of 10 mPa · s or more and 500 mPa · s or less,
The recording head is characterized in that the ink heated to 30 ° C. or more and 150 ° C. or less by the heating device is ejected into ink droplets of 2 pl or more and 20 pl or less.

  As described above, according to the fourth aspect of the present invention, the ink is heated to 30 ° C. or more and 150 ° C. or less by the heating device, whereby the viscosity of the ink when discharged from the recording head is reduced.

The invention according to claim 5 is the inkjet printer according to any one of claims 1 to 4,
The ink is a photocurable ink that cures when irradiated with light,
A light irradiation device for irradiating light onto the ink landed on the recording medium is provided.

  Thus, according to the fifth aspect of the present invention, ink can be fixed on a recording medium having no ink absorption by using a photocurable ink.

  According to a sixth aspect of the present invention, in the ink jet printer according to the fifth aspect, the ink is a cationic polymerization type photocurable ink containing a cationic polymerizable compound.

  Thus, according to the invention described in claim 6, since the cationic curable ink has higher sensitivity to ultraviolet rays and less inhibition of the polymerization reaction by oxygen than the radical curable ink, it is ejected onto the recording medium. The illuminance required for the curing of the formed ink can be reduced.

  According to a seventh aspect of the invention, in the ink jet printer according to the fifth or sixth aspect, the recording medium is a non-absorbing recording medium that does not absorb the ink.

  Thus, according to the seventh aspect of the invention, since the recording medium is non-absorbable with respect to ink, it is possible to prevent the ink from bleeding into the recording medium.

  According to the first aspect of the present invention, since the evaporation of water in the ink is prevented, an increase in ink viscosity can be prevented. In addition, there is an effect that it is possible to provide an ink jet printer capable of preventing occurrence of ink ejection failure due to an increase in ink viscosity and obtaining a high-quality recorded image.

  According to the second aspect of the present invention, the control unit changes the output of the cooling device in accordance with the detection result of the detection device, so that the moisture in the ink hardly evaporates regardless of the ink amount or the environmental temperature. Since the temperature is maintained, an increase in ink viscosity can be prevented. Therefore, it is possible to provide an ink jet printer capable of preventing occurrence of ink ejection failure due to an increase in ink viscosity and obtaining a high-quality recorded image.

  According to the third aspect of the present invention, the ink is maintained at a temperature at which the water in the ink hardly evaporates by the cooling device including at least one of the Peltier element and the cooling fan, and the increase in the ink viscosity can be prevented. Therefore, it is possible to provide an ink jet printer capable of preventing occurrence of ink ejection failure due to an increase in ink viscosity and obtaining a high-quality recorded image.

  According to the invention described in claim 4, it is possible to prevent ink ejection failure due to an increase in ink viscosity in the sub ink tank, and the ink when the ink is ejected from the recording head is reduced in viscosity by the heating device. Since ejection can be performed stably, it is possible to provide an ink jet printer capable of preventing the occurrence of ink ejection failure due to ink clogging at the ejection port and obtaining a high-quality recorded image.

  According to the fifth aspect of the present invention, it is possible to prevent an ink discharge failure due to an increase in the ink viscosity in the sub ink tank, and also on a recording medium having no ink absorption by using an ultraviolet curable ink. Since the ink can be fixed, it is possible to provide an ink jet printer capable of obtaining a high-quality recorded image even with a recording medium having no ink absorbability.

  According to the sixth aspect of the present invention, it is possible to prevent ink discharge failure due to an increase in ink viscosity in the sub ink tank, and the cationic curable ink can be cured with low illuminance ultraviolet rays. There is an effect that it is possible to provide an ink jet printer capable of obtaining a high-quality, high-definition recorded image having a small diameter.

  According to the seventh aspect of the invention, it is possible to prevent an ink discharge failure due to an increase in the ink viscosity in the sub ink tank and to prevent the ink from bleeding into the recording medium. There is an effect that an ink jet printer capable of obtaining a high-quality recorded image can be provided.

The best mode for carrying out the inkjet printer of the present invention will be described below with reference to the drawings.
An ink jet printer 1 shown in FIG. 1 is an ink jet printer using a serial recording head. The ink jet printer 1 has a platen 2, and the platen 2 supports a recording medium 3 from a non-recording surface. At both ends of the platen 2, a conveying device 4 that conveys the recording medium 3 is provided. The conveying device 4 conveys the recording medium 3 in the sub-scanning direction X. A guide rail 5 extending in the main scanning direction Y is provided above the recording surface of the recording medium 3 supported by the platen 4. A carriage 6 is supported on the guide rail 5, and the carriage 6 can be reciprocated in the main scanning direction Y by a carriage transport device 15.

  A recording head 7 is mounted on the carriage 6, and a plurality of ink discharge ports (not shown) for discharging photocurable ink to the recording medium 3 are arranged on the surface of the recording head 7 facing the recording medium 3. They are arranged linearly along the scanning direction X. The amount of ink discharged from the ink discharge port is 2 to 20 pl (picoliter) per dot.

  Inside the recording head 7 is provided a heating device 8 capable of heating the temperature of the ink ejected from the ink ejection port to 30 ° C. or more and 150 ° C. or less. It has come to be. Further, an ultraviolet irradiation device 9 for irradiating the ink landed on the recording medium 3 with ultraviolet light is loaded on the downstream side of the carriage 6 in the sub-scanning direction X from the recording head 7. Is cured by irradiation.

  Furthermore, a substantially rectangular parallelepiped sub-ink tank 10 connected to the recording head 7 via the head supply pipe 11 is stacked on the upstream side of the recording head 7 of the carriage 6 in the sub-scanning direction X. A side surface of the sub ink tank 10 is provided with a Peltier unit 31 having a substantially U-shaped cross section. The Peltier unit 31 is in contact with each of the three side surfaces of the sub ink tank 10. . On the side of the Peltier unit 31 facing the ink tank 23, there is provided a Peltier element (not shown) that generates a temperature difference between two types of metal by energization to dissipate heat. A cooling fan 32 is provided at a position facing the upper surface of the sub ink tank 10. The Peltier unit 31 and the cooling fan 32 constitute a cooling device that maintains the ink stored in the sub ink tank 10 at a predetermined set temperature. Further, a sub pump 12 is attached to the sub ink tank 10 in order to send ink to the recording head 7.

  Further, one end of a sub tank supply pipe 13 is connected to the sub ink tank 10, and an ink tank 23 having a larger capacity than that of the sub ink tank 10 is connected to the other end of the sub tank supply pipe 13. A pressure feed pump 14 is attached in the middle of the sub tank supply pipe 13 so as to pressure feed ink from the ink tank 23 to the sub ink tank 10.

  FIG. 2 shows a control device for controlling the ink jet printer 1 according to the present embodiment. This control device includes, for example, a CPU 40, a RAM 41, and a ROM 42. A processing program recorded in the ROM 42 is stored in the RAM 41. A control unit 43 that expands and executes the processing program by the CPU 40 is provided.

  This control unit 43 follows the processing program described above, such as the transport device 4, the recording head 7, the carriage transport device 15, the heating device 8, the ultraviolet irradiation device 9, the sub pump 12, the pressure feed pump 14, the Peltier unit 31, and the cooling fan 32. The operation of each device is controlled based on the operation status and the like.

  The control unit 43 is connected to a temperature input unit 52 for setting the ink stored in the sub ink tank 10 to an arbitrary temperature in the range of −10 ° C. to 30 ° C., and the control unit 43 is connected to the temperature input unit. Based on the input information from 52, the Peltier unit 31 and the cooling fan 32 are controlled to maintain the ink at the set temperature.

  In particular, the control unit 43 includes a consumption amount detection device 50 that detects the amount of ink consumed from the sub ink tank 10 in order to detect the amount of ink stored in the sub ink tank 10, and the periphery of the sub ink tank 10. And an environment detection device 51 that detects the environmental temperature of the device.

  The control unit 43 calculates the amount of ink stored in the sub ink tank 10 based on the detection information of the consumption amount detection device 50, controls the Peltier unit 31 and the cooling fan 32 based on the calculation result, and supplies the ink. The temperature set above is maintained. That is, when the amount of ink calculated from the detection information of the consumption amount detection device 50 is large, the control unit 43 controls the output of the Peltier unit 31 and the cooling fan 32 to increase the cooling efficiency, When the amount of ink stored in the ink tank decreases due to use, the output of the Peltier unit 31 and the cooling fan 32 is reduced to control to prevent excessive cooling.

  The control unit 43 controls the Peltier unit 31 and the cooling fan 32 based on the detection information of the environment detection device 51, and maintains the ink at the set temperature. That is, when the environmental temperature is higher than the set temperature, the control unit 43 controls the output of the Peltier unit 31 and the cooling fan 32 to increase the cooling efficiency. Further, when the environmental temperature is lower than or equal to the set temperature, the control unit 43 controls the output of the Peltier unit 31 and the cooling fan 32 to be lowered so as to lower the cooling efficiency. Yes.

Next, the ink used in this embodiment will be described.
The ink is an ultraviolet curable ink that cures when irradiated with ultraviolet rays and records an image. The reaction of curing the UV curable ink is called UV curing reaction, and the method irradiates light having a wavelength of 200 to 400 nm, that is, UV light to the UV curable resin composed of a prepolymer, a monomer, a photopolymerization initiator, and an additive. The resin is cured in a short time. As the ultraviolet curable ink containing an ultraviolet curable resin as a binder, among the components contained in the ultraviolet curable resin, those containing at least a polymerizable monomer, a photoinitiator, and a coloring material are preferable.

UV curable inks are roughly classified into radical polymerization inks containing radical polymerization compounds as polymerization compounds and cationic polymerization inks containing cationic polymerization compounds.
As a reaction of radical polymerization, when UV light is irradiated, the photopolymerization initiator becomes a radical, which approaches the polymerizable double bond (unsaturated group) of the polymerizable monomer and activates the double bond portion. This is a reaction that is linked in a chain, and the photopolymerization reaction is hindered by oxygen in the air. Compared to treat the curing of the surface of the UV curable resin in contact with air in a short time. A large amount of UV irradiation is required. Therefore, the installation of a high-output light source device leads to an increase in the length of the device and an increase in the manufacturing cost of the device.

  On the other hand, the reaction of cationic polymerization is a reaction initiated by a salt excited by ultraviolet light drawing hydrogen from a hydrogen donor compound to release hydrogen ions, which then attack the target. The ink on the recording medium can be cured without being obstructed by oxygen in the air during irradiation.

Accordingly, a cationic polymerization ink that has little or no inhibition of polymerization reaction by oxygen is superior in functionality and versatility. Therefore, in this embodiment, a cationic polymerization ink is particularly used.
As the cationic polymerizable monomer contained in the cationic ultraviolet curable ink, various known cationic polymerizable monomers can be used in combination. For example, JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, Examples include epoxy compounds, vinyl ether compounds, and oxetane compounds exemplified in JP-A No. 2001-220526.

  Of the aromatic epoxides, alicyclic epoxides, and aliphatic epoxides, aromatic epoxides and alicyclic epoxides are preferable, and alicyclic epoxides are particularly preferable in view of fast curability. In the present invention, one of the epoxides may be used alone, or two or more may be used in appropriate combination.

Among vinyl ether compounds, in consideration of curability, adhesion, and surface hardness, di- or trivinyl ether compounds are preferable, and divinyl ether compounds are particularly preferable. In the present invention, one of the above vinyl ether compounds may be used alone, or two or more thereof may be used in appropriate combination.
The ink has a viscosity at 30 ° C. of 10 mPa · s or more and 500 mPa · s or less. As a result, the ink does not easily bleed onto the recording medium as in the case where the ink viscosity is less than 10 mPa · s, and clear recording cannot be performed, and the image quality is improved as in the case where the ink viscosity exceeds 500 mPa · s. There is no loss of smoothness.
Further, this ink has a viscosity at 30 ° C. of 40 mPa · s or more and 500 mPa · s or less. Further, this ink preferably has a viscosity at 60 ° C. of 3 mPa · s or more and 30 mPa · s or less, more preferably 3 mPa · s or more and 20 mPa · s or less. This is because if the ink viscosity is less than 3 mPa · s, a problem occurs in high-speed ejection, and if it exceeds 30 mPa · s, the ejection properties deteriorate.

  In addition, the ink is preferably maintained at 5 ° C. to 15 ° C., and more preferably at 10 ° C., in order to prevent evaporation of moisture in the ink.

  Moreover, as a light source provided in the ultraviolet irradiation device 9, a mercury lamp, a metal halide lamp, an excimer lamp, an ultraviolet laser, an LED (Light Emitting Diode), or the like can be applied. X-rays, X-rays, infrared rays, etc. may be used. In other words, the ink used in the present embodiment includes: A polymerizable compound that is polymerized and cured with light other than ultraviolet light and a photoinitiator that initiates a polymerization reaction between the polymerizable compounds with light other than ultraviolet light may be applied. In addition, when using the photocurable ink which hardens | cures with light other than an ultraviolet-ray, the light source which irradiates the light for hardening the said ink is used.

  When using the ultraviolet curable ink as described above, the ink ejected from the ejection port is irradiated with ultraviolet rays of 200 to 400 nm from the light source, and the ink is cured to form an image.

Here, the “recording medium 3” used in the present embodiment will be described.
As the recording medium 3, either a non-absorbing recording medium or an absorptive recording medium can be used.

As the non-absorbing recording medium, a transparent or opaque non-absorbing 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. It is preferable to use a resin film having a thickness of 2 μm (micrometer) to 100 μm (preferably 6 μm to 50 μm). 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.
Examples of the absorbent recording medium include various papers such as plain paper, recycled paper, and glossy paper that are applied to ordinary ink jet printers, various fabrics, various nonwoven fabrics, and the like. Moreover, as a form of the recording medium 2, a roll shape, a cut sheet shape, a plate shape, or the like is applicable.

Next, the operation of this embodiment will be described.
When image information is input to the ink jet printer 1, the sub pump 12 operates to supply ink from the sub ink tank 10 to the recording head 7, and the ink is heated to 30 ° C. or more and 150 ° C. or less by the heating device 8. Ink is ejected from the ink ejection ports of the recording head 7 based on the image information. The ejected ink sequentially reaches the recording medium 3. Then, ultraviolet rays are sequentially irradiated from the ultraviolet irradiation device 9 to the ink landed along with the conveyance of the recording medium 3, and the ink is cured on the recording surface of the recording medium 3 to record an image.

  As the image is recorded on the recording medium 3, the amount of ink stored in the sub ink tank 10 decreases, but the ink is supplied from the ink tank 23 to the sub ink tank 10 via the sub tank supply pipe 13 by the pressure feed pump 14. Is done.

  As the image is recorded on the recording medium 3, the amount of ink stored in the sub ink tank 10 decreases, but the ink is supplied from the ink tank 23 to the sub ink tank 10 via the sub tank supply pipe 13 by the pressure feed pump 14. Is done.

  The control unit 43 operates the Peltier unit 31 and the cooling fan 32 to maintain the ink stored in the sub ink tank 10 at the set temperature input from the temperature input unit 52. In the present embodiment, the input temperature is set to 10 ° C. at which the water in the ink hardly evaporates.

  At this time, the control unit 43 performs efficient cooling control by changing the outputs of the Peltier unit 31 and the cooling fan 32 according to the detection information from the consumption detection device 51 and the environment detection device 52. .

  As described above, according to the present embodiment, the sub ink tank 10 is provided with the Peltier unit 31 and the cooling fan 32, and these are 10 ° C. at which the water in the ink hardly evaporates. Since the set temperature is maintained, evaporation of moisture in the ink can be prevented. Therefore, it is possible to prevent an increase in ink viscosity due to evaporation of moisture. Ink discharge failure due to an increase in ink viscosity does not occur, and a high-quality recorded image can be obtained.

  Moreover, since the control part 43 changes the output of the Peltier unit 31 and the cooling fan 32 based on the detection information of the consumption detection apparatus 50 and the environment detection apparatus 51, when the ink amount and environmental temperature of the sub ink tank 10 change Even so, the ink can be maintained at the set temperature, and the evaporation of moisture in the ink can be prevented. Therefore, regardless of the amount of ink and the environmental temperature, there is no occurrence of defective ink discharge due to an increase in ink viscosity, and a high-quality recorded image can be obtained.

  Further, in the ink jet printer 1 of the present embodiment, since the discharge amount from the ink discharge port is set to 2 pl or more and 20 pl or less per dot, the image quality density drop that occurs when the discharge amount is less than 2 pl and the discharge amount is 20 pl or more. It is possible to prevent a reduction in image quality due to an increase in the generated dot diameter. In addition, since the ink is heated to 30 ° C. or more and 150 ° C. or less during ejection, the viscosity can be such that ink clogging is less likely to occur at the ejection port of the recording head 7. Therefore, since ink can be appropriately discharged, it is possible to prevent deterioration in image quality due to defective discharge.

  In the present embodiment, the cooling device includes the Peltier unit 31 and the cooling fan 32. However, the present embodiment is not limited thereto, and the cooling device includes any one of the Peltier unit 31 and the cooling fan 32. A configuration may be used. Further, a water cooling system or an air cooling system may be applied as the cooling device.

1 is a side view illustrating a configuration of an 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.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printer 3 Recording medium 7 Recording head 8 Heating device 9 Ultraviolet irradiation device 10 Sub ink tank 11 Head supply pipe 12 Sub pump 13 Sub tank supply pipe 14 Pressure feed pump 23 Ink tank 31 Peltier unit 32 Cooling fan

Claims (7)

In an inkjet printer comprising: a recording head provided with an ejection port for ejecting ink to a recording medium; and a sub ink tank for storing the ink supplied to the recording head.
An ink jet printer, comprising: a cooling device that maintains ink stored in the sub ink tank at a predetermined set temperature. A control unit that controls the cooling device, a detection device that detects at least one of the amount of ink stored in the sub ink tank and the ambient temperature around the sub ink tank, and ink stored in the sub ink tank. A temperature input unit for setting an arbitrary temperature in the range of 10 ° C. to 30 ° C., and
The inkjet printer according to claim 1, wherein the control unit controls the cooling device according to a detection result of the detection device, and maintains the temperature set by the temperature input unit.   The inkjet printer according to claim 1, wherein the cooling device includes at least one of a Peltier element and a cooling fan. A heating device for heating the ink supplied to the recording head to a predetermined temperature;
The ink has a viscosity at 30 ° C. of 10 mPa · s or more and 500 mPa · s or less,
4. The recording head according to claim 1, wherein the recording head discharges the ink heated to 30 ° C. or more and 150 ° C. or less by the heating device so as to be ink droplets of 2 pl or more and 20 pl or less. An ink jet printer according to claim 1. The ink is a photocurable ink that cures when irradiated with light,
The inkjet printer according to claim 1, further comprising a light irradiation device that irradiates light onto the ink landed on the recording medium.   6. The ink jet printer according to claim 5, wherein the ink is a cationic polymerization type photocurable ink containing a cationic polymerizable compound.   The inkjet printer according to claim 5, wherein the recording medium is a non-absorbing recording medium that does not absorb the ink.

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