JP2003341099A - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet printer capable of supplying a high-viscosity ink from a sub-tank to a recording head in a condition that the viscosity of the ink is stabilized. <P>SOLUTION: This inkjet printer 1 is equipped with a sub-tank 3 for temporarily reserving a high-viscosity ink to be supplied to the recording head from an ink tank. The inkjet printer 1 comprises a heater wire 34 for heating the high-viscosity ink reserved in the sub-tank 3, a temperature sensor 36 for detecting the temperature of the ink, and a control means for controlling the heater wire 34 so as to set the temperature of the ink reserved in the sub-tank 3 to be in a preset temperature based on the detected result of the temperature sensor 36. The high-viscosity ink flowing in the sub-tank 3 from the ink tank is allowed to flow into the recording head by sequentially passing through each of liquid chambers 3a, 3b, 3c in the sub-tank 3. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet printer that records an image on a recording medium by ejecting ink droplets on the recording medium.

[0002]

2. Description of the Related Art Ink jet printers record an image on a recording medium by supplying the ink from an ink tank that stores the ink to the recording head and discharging the supplied ink from the recording head onto the recording medium to land it. To do.
Here, when a highly viscous ink having a high viscosity at room temperature and having a low viscosity as the temperature rises is used as the ink, there is an advantage that a recorded image is less likely to bleed onto a recording medium and a clear image can be recorded.

However, when the ink is ejected from the recording head as it is without being heated, the ink remains highly viscous, and therefore, due to flow path resistance in the ink supply path for supplying the ink from the ink tank to the recording head. Pressure loss increases. At this time, so-called “nozzle missing” occurs, in which the ink is not normally ejected from the nozzles of the recording head, and the image quality of the recorded image is not stable, resulting in deterioration of the image quality.

Here, as described above, since the high viscosity ink has the property of lowering its viscosity as the temperature rises, for example,
It is conceivable that the ink supply system including the ink tank and the ink supply path is heated by a heating means such as a heater to reduce the viscosity of the ink to reduce the pressure loss and stabilize the supply of the ink to the recording head.

[0005]

However, in order to stabilize the ink supply to the recording head, the viscosity of the ink in the ink supply path, in other words, the temperature of the ink supply system should be kept as uniform as possible. is necessary. what if,
When the temperature of the ink supply system is non-uniform, the viscosity of the ink existing in the ink supply system also becomes non-uniform. For example, if only the ink tank of the ink supply system is heated, the temperature of the ink changes and the viscosity of the ink also changes while the ink is flowing or staying in the ink supply path or the recording head, that is, The viscosity of the ink becomes non-uniform.

As described above, if the temperature of the ink supply system is non-uniform, the viscosity of the ink also becomes non-uniform, and as a result, the pressure loss fluctuates in the ink supply path and the quality of the recorded image becomes unstable. Will be things. That is, recording by an inkjet printer is performed by ejecting ink from the recording head while the recording head is main-scanned on the recording medium. However, if the viscosity of the ink is not uniform, the ejection speed of the ink varies and the recording is performed. Ink is not ejected to a desired position on the medium, and as a result, the recorded image is displaced.
Further, since the viscosity of the ink also affects the ejection amount of the ink, if the viscosity of the ink is not uniform, the amount of the ejected ink becomes unstable, and it is not possible to obtain a stable dot diameter.

In order to make the temperature of the ink supply system uniform, it is considered that all the ink supply system including the ink tank and the ink supply path should be heated. However, the members constituting the ink supply system have a large heat capacity. In fact, it is difficult to control the temperature of the ink existing in the ink supply path to be constant, which is a problem.

Therefore, a sub-tank capable of temporarily storing the ink from the ink tank is provided between the ink tank and the recording head, and the ink is pressure-fed once from the ink tank to the sub-tank to heat or adjust the temperature of the sub-tank. It is considered efficient to supply the ink in the sub-tank to the recording head in a low-viscosity state. However, since the ink before being pressure-fed to the sub tank is left at room temperature, the ink to be pressure-fed to the sub tank is pressure-fed to the sub tank while having high viscosity.

Therefore, even if the temperature of the ink in the sub tank is adjusted, the temperature distribution of the ink in the sub tank becomes uneven every time the ink is supplied from the main tank.
The ink viscosity also becomes non-uniform. Therefore, highly viscous ink cannot be supplied from the sub tank to the recording head while the viscosity is stable.

An object of the present invention is to provide an ink jet printer which can supply highly viscous ink from a sub tank to a recording head in a state where the viscosity is stable.

[0011]

In order to solve the above-mentioned problems, the invention according to claim 1 uses an ink tank for storing a high-viscosity ink whose viscosity becomes low as the temperature rises, and the high-viscosity ink as a recording medium. A recording head for discharging, a sub-tank having two or more liquid chambers capable of temporarily storing the high-viscosity ink supplied from the ink tank to the recording head, and heating the high-viscosity ink stored in the sub-tank Heating means, a detection means for detecting the temperature of the high-viscosity ink stored in the sub-tank, and a temperature of the high-viscosity ink stored in the sub-tank is preset based on a detection result of the detection means. Control means for controlling the heating means so as to reach a set temperature, the high viscosity ink flowing from the ink tank into the sub tank is And it flows through the respective liquid chambers of the tank in order, characterized in that flow out to the recording head.

According to the first aspect of the invention, the high-viscosity ink stored in the ink tank is temporarily stored in each liquid chamber of the sub tank, and then supplied from the sub tank to the recording head. At this time, the high-viscosity ink that has flowed into the sub tank from the main tank first flows into the liquid chamber upstream in the flow direction in the sub tank, and then flows through each liquid chamber in order toward the liquid chamber downstream in the flow direction. Then, finally, it flows out from the liquid chamber downstream in the flow direction to the recording head.

Here, the detection means detects the temperature of the high-viscosity ink in the sub-tank, and the control means controls the heating means so that the temperature of the high-viscosity ink stored in the sub-tank becomes a set temperature based on the detection result of the detection means. The high-viscosity ink in the sub-tank is heated in each liquid chamber and temperature-controlled so as to flow from the upstream liquid chamber to the downstream liquid chamber. Therefore, the high-viscosity ink flowing from the main tank to the sub-tank flows through the sub-tank while gradually approaching the desired temperature each time it passes through each liquid chamber, and when stored in the downstream liquid chamber, it comes closest to the set temperature. It will be. Then, the high-viscosity ink that has flowed into the downstream liquid chamber flows out from the downstream liquid chamber to the recording head while approaching the set temperature. This allows
Since the temperature of the high-viscosity ink flowing from the downstream liquid chamber to the recording head can be constantly stabilized, the high-viscosity ink can be supplied from the sub tank to the recording head with the viscosity being stabilized.

According to a second aspect of the invention, the detection means and the heating means are provided for each liquid chamber, and the control means controls the heating means based on the detection result of each detection means. The heating may be controlled for each liquid chamber.

According to the second aspect of the present invention, since the control means controls the heating of the heating means for each liquid chamber, the temperature of the highly viscous ink stored in each liquid chamber becomes the set temperature in each liquid chamber. You can get closer.

According to a third aspect of the present invention, in the ink jet printer according to the second aspect, the control means controls the heating of the liquid chamber on the downstream side in the flowing direction of the high-viscosity ink and the heating of the liquid chamber on the upstream side. It is characterized by controlling with higher accuracy than heating.

According to the third aspect of the invention, the control means controls the heating of the liquid chamber on the downstream side in the flow direction of the high-viscosity ink with higher accuracy than the heating of the liquid chamber on the upstream side. The higher the viscosity of the ink stored in the liquid chamber, the closer the temperature is to the set temperature. Therefore, the highly viscous ink can be supplied from the sub tank to the recording head in a state where the viscosity of the highly viscous ink is more stable.

According to a fourth aspect of the present invention, in the ink jet printer according to the second or third aspect, the liquid chamber on the downstream side in the flow direction of the high viscosity ink is conducted from the heating means from the liquid chamber on the upstream side. It is characterized in that the amount of heat applied is small.

According to the fourth aspect of the present invention, the liquid chamber on the downstream side in the flow direction has a smaller amount of heat conducted from the heating means than the liquid chamber on the upstream side. The viscous ink has a smaller effect of heating from the heating means.
Therefore, the higher viscosity ink stored in the liquid chamber on the downstream side has less temperature fluctuation, and the viscosity of the high viscosity ink becomes stable.
As a result, the high-viscosity ink can be supplied from the sub tank to the recording head while the viscosity of the high-viscosity ink is more stabilized.

According to a fifth aspect of the invention, in the ink jet printer according to any one of the first to fourth aspects,
Each of the liquid chambers of the sub-tank is partitioned by a plurality of partition walls having different heights, and the height of each partition wall becomes lower toward the downstream side in the flowing direction of the highly viscous ink.

According to the fifth aspect of the present invention, the height of each partition wall becomes lower toward the downstream side in the flowing direction of the highly viscous ink. Therefore, the ink flowing in each liquid chamber in the sub-tank is at the upstream side in the flowing direction. From the liquid chamber to the downstream liquid chamber, it overflows (overflows) so as to exceed each partition wall in order, and flows through each liquid chamber in order. Therefore, the ink that has flowed from the main tank to the sub tank can be circulated in the sub tank with a simple configuration in which the height of each partition wall is lowered toward the downstream side in the circulation direction.

Further, as in the ink jet printer according to the sixth aspect of the invention, the high viscosity ink may be an ink which is cured by being irradiated with light.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an ink jet printer of the present invention (hereinafter simply referred to as "printer") will be described below with reference to the drawings. However, the scope of the present invention is not limited to the illustrated example. FIG. 1 is a perspective view showing a main part of the printer 1.

The printer 1 according to the present embodiment ejects ink as droplets toward the recording medium 99, and thereafter,
An image is recorded on the recording medium 99 by irradiating the area of the recording medium 99 where the ink droplets have landed with light. The “ink” referred to here is an ink that has a high viscosity at room temperature and a low viscosity as it is heated.
Viscosity at 0 ° C. is 30 to 3000 mPa · s, preferably 50 to 1000 mPa · s, more preferably 10
It means an ink of 0 to 500 mPa · s. 30 mPa
In the case of s or less, clear recording cannot be performed because the recording medium 99 such as recording paper easily bleeds. In addition, 3000 mP
Above a · s, the smoothness of the image quality is lost. Furthermore, this ink is more preferably a liquid having a viscosity at 60 ° C. of 3 to 30 mPa · s. If it is less than 3 mPa · S, a problem may occur in high-speed ejection from the recording head 2 described later, and if it exceeds 30 mPa · s, the ejection property may be deteriorated. Further, particularly when ejected from a recording head including a piezo element, this ink is preferably a liquid having a viscosity of 3 to 30 mPa · s. The viscosity of this ink is JIS Z 880.
The viscosity was measured by the liquid viscosity-measuring method specified in No. 3, and a rotational viscosity type (viscotester) model VT07L manufactured by HAAKE was used for the actual measurement of the viscosity. Furthermore, the "ink" referred to here is an ink having the property of being cured by irradiation with light. The “light” here will be described later.

Also, the "recording medium 99" according to the present embodiment.
As the material, it is possible to apply paper, resin, or any other material capable of recording an image by the printer 1. In addition to a recording medium having good ink absorbability (for example, a paper recording medium), ink It may be a recording medium having no absorptivity or a recording medium having a low ink absorptivity. A "recording medium having no ink absorbability or a recording medium having low ink absorbability" is a recording medium formed from a material having no ink absorbability or a material having low ink absorbability, or a material having no ink absorbability or an ink. A recording medium or the like having a surface layer (recording layer) made of a material having low absorbability. Examples of the “material having no ink absorption or a material having low ink absorption” include, for example,
Examples include various plastics and metals.

As shown in FIG. 1, the printer 1 has, as its basic configuration, a plurality of recording heads 2, 2, ... For ejecting ink droplets onto a recording medium 99, and a plurality of inks for supplying ink to each recording head 2. Sub-tanks 3, 3, ... and main scanning direction A
A carriage mechanism 4 having a carriage 4a that can move along the carriage 4, a maintenance unit 6 that performs maintenance of each recording head 2, a home position 7 in which an unused carriage 4 waits, and a plurality of inks that store ink of each color. ..., a plurality of pressurizing pumps 9, 9, ... connected to each main tank 8, an ink supply member 10 for supplying ink from each main tank 8 to each sub tank 3, and recording The platen 11 for sucking and holding the non-recording surface of the medium 99, a feeding mechanism (not shown) for feeding the recording medium 99 in the sub-scanning direction B, and the recording medium 9 to which ink is attached.
An irradiation unit (not shown) that irradiates 9 with light, and a control device 20 (see FIG. 5) that controls the operation of each of the above members are provided.

The feed mechanism includes a feed motor and a feed roller (not shown), and has a function of feeding the recording medium 99 in the sub-scanning direction B by driving the feed motor. Specifically, the feed mechanism intermittently feeds the recording medium 99 in accordance with the operation of the carriage 4a described later, that is, the feeding and stopping of the recording medium 99 is repeated.

The platen 11 sucks and holds the non-recording surface of the recording medium 99 conveyed in the sub-scanning direction B.
Specifically, a suction chamber including a fan is provided below the platen 11, and a suction port including a plurality of small holes communicating with the suction chamber is provided on the back side of the platen 11. Therefore, the non-recording surface of the recording medium 99 on the platen 11 can be sucked by driving the fan of the suction chamber, and the recording medium 99 is brought into close contact with the platen 11 by the cooperation of the driving of the fan and the transport mechanism. In this state, the sheet can be conveyed in the sub-scanning direction B.

Each main tank 8 is, for example, a replaceable ink cartridge, and each main tank 8 stores one color of ink. That is, one ink tank 8 stores ink of any one of several colors. Basically, different color inks are stored in each ink tank 8, but the same color ink may be stored in two or more ink tanks 8, 8 (...). The ink colors applied to the printer 1 are as shown in FIG.
As shown in, each process color having yellow (Y), magenta (M), cyan (C), and black (K) as basic colors, and light yellow (LY) and light magenta (L).
M), light cyan (LC), light black (LK)
Etc. are applicable, and in addition, special colors such as white (W), red (R), blue (B), and green (G) are also applicable.

The ink supply member 10 is a member that communicates from a plurality of main tanks 8, 8, ... To a plurality of sub tanks 3, 3, ... For each color of ink, and from each main tank 8 to the main tank 8. Ink of each color is supplied to the communicating sub tank 3. This ink supply member 1
0 is formed of a flexible member so that it can follow the movement of the carriage 4a described later.

A plurality of pressurizing pumps 9, 9, ... Are interposed between the ink supply member 10 and a plurality of main tanks 8, 8 ,. Each pressurizing pump 9 is provided for each main tank 8. Each pressurizing pump 9 is capable of supplying ink from each main tank 8, and each pressurizing pump 9 supplies ink from each main tank 8 to the sub tank 3 communicating with the main tank 8. Done.

The plurality of sub tanks 3, 3, ... Temporarily store the inks of the respective colors stored in the plurality of main tanks 8, 8 ,. Ink is supplied to each sub-tank 3 from a main tank 8 communicating with the sub-tank 3 through an ink supply member 10. Further, the recording heads 2 are connected to the sub-tanks 3, respectively, and have a function of supplying the ink that is temporarily stored to the recording heads 2. Each sub-tank 3 has a carriage 4 described later.
It is mounted on a and follows the movement of the carriage 4a. The configuration of each sub tank 3 will be described later.

The plurality of recording heads 2, 2, ... Are connected to the plurality of sub tanks 3, 3 ,.
Like the sub-tank 3, the sub-tank 3 is mounted on a carriage 4a described below and follows the movement of the carriage 4a. Then, each recording head 2 ejects the ink supplied from the sub-tank 3 connected to the recording head 2 onto the recording medium 99 while the carriage 4a is moving. Specifically, each recording head 2
Is provided with a predetermined number (for example, 128) of nozzles arranged in a line along the main scanning direction A, and each recording head 2 outputs from the sub tank 3 based on a drive signal output from the control device. The supplied color ink is ejected as an ink droplet from each nozzle onto the recording medium 99.

The ejection amount M of the ink droplet ejected from each nozzle is 2 pl ≦ (ejection amount M) ≦ 20.
pl is preferable, and 2 pl ≦ (discharge amount M) ≦ 1
0 pl is more preferable, and 4 pl ≦ (discharge amount M) ≦ 7 pl is further preferable. The discharge amount M is
If it is 20 pl or more, high-definition printing is difficult and 2p
This is because if it is 1 or less, the density of the image formed on the recording medium 99 becomes low. Also, the recording medium 9
The droplet diameter of the ink droplet that has landed on No. 9, that is, the dot diameter D is preferably 50 μm ≦ (dot diameter D) ≦ 200 μm, more preferably 50 μm ≦ (dot diameter D) ≦ 150 μm, and 55 μm ≦ (Dot diameter D) ≤
More preferably, it is 100 μm. Dot diameter is 5
This is because if it is 0 μm or less, the density of the image formed on the recording medium 99 becomes low, and if it is 200 μm or more, high-definition printing is difficult.

As a driving force for ejecting ink in each recording head 2, it is preferable to use a piezoelectric action of a piezoelectric material which has a wide range of application to ink and is capable of high-speed ejection. Specifically, it is an ink jet head method in which an electrode film is formed inside a fine groove formed on a piezoelectric substrate and is covered with an insulating film to form an ink flow path.

Here, the configuration of each recording head 2 will be described with reference to FIGS. The configuration described below is common to all the recording heads 2, 2, ... Among the plurality of recording heads 2, 2, ..., One of the recording heads 2 will be described. FIG. 2A is a cross-sectional view of the recording head 2, and FIG. 2B is an enlarged view taken along the line (IV)-(IV) of FIG. 2A. FIG. 3 is an exploded perspective view of the recording head 2. As shown in FIGS. 2 and 3, the recording head 2 includes a substrate 2a, a piezoelectric element 2b, and a flow path plate 2
c, the ink flow path 2d, the wall portion 2e, the common liquid chamber constituent member 2f, the common liquid chamber 2g, the ink supply pipe 2h,
Nozzle plate 2i, nozzle 2j, drive circuit printed board (PCB) 2k, lead wire 21 and drive electrode 2
m, a groove 2n, a protective plate 2o, a fluid resistance 2p, electrodes 2q and 2r, an upper partition wall 2s, a heater 2t, a heater power supply 2u, and a heat transfer member 2v.

In the integrated recording head 2, the laminated piezoelectric element 2b having the electrodes 2q and 2r is grooved in the direction of the ink flow path 2d so as to correspond to the ink flow path 2d. Driving piezoelectric element 2x and non-driving piezoelectric element 2y
It is divided into and. A filler is enclosed in the groove 2n.
The flow path plate 2c is joined to the grooved piezoelectric element 2b through the upper partition wall 2s. That is, the upper partition 2s
Is a wall 2 that separates the flow path adjacent to the non-driving piezoelectric element 2y.
supported by e and. The width of the driving piezoelectric element 2x is slightly narrower than the width of the ink flow path 2d. The drive piezoelectric element 2x selected by the drive circuit on the drive circuit printed board (PCB) 2k changes in the thickness direction when a pulsed signal voltage is applied. As a result, the volume of the ink flow path 2d changes via the upper partition 2s, and as a result, ink droplets are ejected from the nozzles 2j of the nozzle plate 2i.

Heaters 2t are adhered on the flow path plate 2c through heat transfer members 2v, respectively. Heat transfer member 2v
Are provided around the nozzle surface. The heat transfer member 2v efficiently transfers the heat from the heater 2t to the flow path plate 2c to heat the ink in the ink flow path 2d, and conveys the heat from the heater 2t to the vicinity of the nozzle surface so as to be in the vicinity of the nozzle surface. The purpose is to warm the air. Therefore,
A material having a high thermal conductivity is used for the heat transfer member 2v. Examples of preferable materials include metals such as aluminum, iron, nickel, copper, and stainless steel, and ceramics such as SiC, BeO, and AlN.

Piezoelectric element 2b in a state where ink is in a liquid state
When is driven, the driving piezoelectric element 2x is displaced in a direction perpendicular to the longitudinal direction of the ink flow path 2d, the volume of the ink flow path 2d is changed, and the ink is ejected as an ink droplet from the nozzle 2j due to the change in the volume. . The piezoelectric element 2b is constantly given a signal to hold it so that the volume of the ink flow passage 2d is reduced, and the ink flow passage 2d is selected with respect to the selected ink flow passage 2d.
Of the nozzle 2 corresponding to the ink flow path 2d by applying a pulse signal that gives a displacement that reduces the volume of the ink flow path 2d again after the displacement of the ink flow path 2d.
The ink is ejected as an ink droplet from j.

The carriage mechanism 4 includes a carriage 4a on which the plurality of recording heads 2, 2, ... And a plurality of sub tanks 3, 3, ... Are mounted, and a main portion of the carriage 4a extending along the main scanning direction A. A guide member 4b for guiding the movement in the scanning direction A, a conveyor belt (not shown) for moving the carriage 4a while supporting the carriage 4a, and a conveyor motor (not shown) for driving the carriage 4a. , Are provided. In this carriage mechanism 4,
When the transport motor is driven, the transport belt operates, and the carriage 4a moves in the main scanning direction A while being guided by the guide member 4b. The moving direction of the carriage 4a is changed according to the rotating direction of the carry motor. Specifically, the carriage 4a reciprocates in the main scanning direction A along the guide member 4b in accordance with intermittent feeding of the recording medium 99, and more specifically, the recording medium 99 stops. While moving, it moves forward, backward, or reciprocates in the main scanning direction A.

Although not shown, the irradiation means is in the sub-scanning direction B.
The recording medium 99 sent to the recording medium 99 is irradiated with light. By irradiating the recording medium 99 with light, the ink droplets adhering to the recording medium 99 are cured to fix the ink on the recording medium 99. It is a thing. This irradiating means is provided with a light source for irradiating the recording medium 99 with light, and this light source is provided on both sides of each recording head 2 in the main scanning direction as disclosed in JP-A-60-132767. It may be mounted on the carriage 4a so as to be arranged along A, or the printer 1 main body so as to cover the entire width of the recording medium 99 that is sent out in the sub-scanning direction B on the downstream side of the platen 11 in the sub-scanning direction B. It may be fixed to.

When the light source is arranged on both sides of each recording head 2, the light source irradiates the recording medium 99 with light while following the main scanning of the carriage 4a, and the light source is from the platen 11 in the sub-scanning direction B. When the recording medium 99 is fixed to the main body of the printer 1 on the downstream side so as to extend across the width of the recording medium 99, the light source irradiates the recording medium 99 with light while being fixed to the main body of the printer 1. In the case of such a configuration, after the ink droplets ejected from each recording head 2 have landed on the recording medium 99, the light source irradiates the recording medium 99 with light for a certain period of time. .

Further, instead of the above-described structure disclosed in Japanese Patent Laid-Open No. 60-132767, a structure using an optical fiber may be used, and light emitted from a collimated light source may be recorded in a plurality of pieces. When the recording medium 9 is applied to the mirror surface provided on the side surface of the head unit including the heads 2, 2 ,.
It may be configured to irradiate the area of the ink droplet 9 where the ink droplet has landed. In any of the above configurations, if the light source is fixed to the printer 1 (including the carriage 4a),
Since the moving part for moving the light source can be omitted, the structure can be inexpensive.

The term "light" as used herein means light in a broad sense and includes ultraviolet rays, electron beams, X-rays, visible rays, infrared rays and the like. However, it is preferable to apply ultraviolet rays in consideration of the curability of ink drops, the cost of a light source, and the like. Further, a mercury lamp, a metal halide lamp, an excimer lamp, an ultraviolet laser, an LED (Light Emitting Diode), or the like can be applied as the “light source” for irradiating ultraviolet rays.

The irradiation of light from the light source is preferably performed each time an ink droplet is ejected from each recording head 2, that is, each time an ink droplet of one color is ejected. In any of the exposure methods described above, it is preferable to prepare two types of light sources (first light source and second light source) and complete the curing of the ink droplets by irradiating the light from the second light source. This is because it contributes to the wettability of the ink droplet of the second color that has landed on the recording medium 99, the adhesiveness between the ink droplets, and the inexpensive assembly of the light source.

It is preferable that the first light source and the second light source have different exposure wavelengths or exposure illuminances. That is, it is preferable to make the irradiation energy of the first light source smaller than the irradiation energy of the second light source. Specifically, the irradiation energy of the first light source is set to 1 to 20%, preferably 1 to 10%, and more preferably 1 to 5% of the total irradiation energy.
By performing irradiation while changing the illuminance, the molecular weight distribution after the ink droplet is cured becomes preferable. It should be noted that if a single light source irradiates with high illuminance at a time, the polymerization rate of the ink composition is increased, but the molecular weight of the polymerized composition (polymer) is small, and the ink droplets landed on the recording medium 99 are small. Of strength is not obtained. A remarkable effect can be obtained with a composition having an extremely low viscosity such as the ink according to the present embodiment.

The wavelength of the light emitted from the first light source is preferably longer than the wavelength of the light emitted from the second light source. In this case, the irradiation of the light from the first light source cures the surface layer of the ink droplets to suppress the ink bleeding on the recording medium 99, and the irradiation of the light from the second light source causes the irradiation line to reach the vicinity of the recording medium 99 which is difficult to reach. It is possible to cure the ink and improve the adhesion between the ink and the recording medium 99. Therefore, in order to accelerate the curing of the inside of the ink droplet that has landed on the recording medium 99, the irradiation line wavelength of the light from the second light source is preferably a short wavelength.

Further, as a characteristic of the configuration of the printer 1 according to the present embodiment, the above-described ink is used, and 0.01 to 0.5 after ink droplets land on the recording medium 99.
After a second, preferably 0.01 to 0.3 seconds, and more preferably 0.01 to 0.15 seconds, the light source is controlled to emit light. In this way, by controlling the time from the landing of the ink droplet on the recording medium 99 to the irradiation of the light from the light source to an extremely short time, the ink droplet landed on the recording medium 99 is cured before being irradiated with the light. Further, it is possible to prevent the recording medium 99 from bleeding. Further, when the porous recording medium 99 is applied, before the ink droplets that have landed penetrate the recording medium 99, it is possible to expose to a deep area where the light from the light source does not reach, so that the residual unreacted monomer can be suppressed. The odor can be reduced. This is because a large synergistic effect can be obtained by using the ink according to this embodiment, and particularly a large effect can be obtained by using an ink having an ink viscosity at 25 ° C. of 35 to 500 mPa · s. That is, by applying such a configuration, it is possible to keep the dot diameter of the landed ink droplets constant, even for various recording media 99 having different surface wettability, and thus the image quality is improved.

When a color image is recorded on the recording medium 99, it is preferable that the inks of low lightness are sequentially superposed. The reason for this is that if a low-brightness ink is layered on top of a high-brightness ink, it is difficult for the radiation from the light source to reach the bottom ink of the high-brightness color, which impairs curing sensitivity and increases residual monomer. This is because the generation of odor and the deterioration of the adhesion between the ink droplets are likely to occur. Regarding the irradiation of light from the light source, it is possible to collectively expose the ink droplets of all colors after ejecting them from each recording head 2, but it is better to expose the ink droplets each time one ink droplet is ejected. It is preferable from the viewpoint of accelerating the curing of.

Further, it is preferable that the plurality of recording heads 2, 2, ... Are substantially transparent to the irradiation rays between the respective recording heads 2. Specifically, it is preferable to apply a configuration in which the recording heads 2 are made of a radiation-transmissive member or no member is arranged. By applying such a simple configuration, it is possible to immediately irradiate light for each color immediately after the ink droplet has landed on the recording medium 99. In the case of direct printing (recording in which ink droplets are ejected during movement in the forward and backward directions of the reciprocating movement of the carriage 4a to form an image), recording by forward movement of the carriage 4a and recording by backward movement Bleeding difference can be prevented (preventing a difference in recorded color between recording when the carriage 4a is moved in the forward direction and recording when the carriage is moved in the backward direction).

As shown in FIG. 1, the maintenance unit 6 is a member provided at the moving end of the carriage 4a, and covers a lower surface of each recording head 2 and a plurality of suction caps 61 for sucking ink from each nozzle. 61, ..., and a blade portion 6 for wiping off the ink remaining on the lower surface of each recording head 2.
2 is provided. The maintenance unit 6 is provided with the plurality of suction caps 61, 61, ..., The blade portion 62, etc., thereby preventing the generation of bubbles and clogging in each nozzle of each recording head 2, and the remaining ink. Etc. are removed. By this maintenance unit 6, the ejection state of ink droplets from each nozzle can be maintained in a good state, and a clear image can be recorded on the recording medium 99.

The home position 7 is as shown in FIG.
At the moving end of the carriage 4a and the maintenance unit 6
It is provided on the opposite side of. Multiple recording heads 2,
, And the carriage 4a are not involved in the recording operation, the plurality of recording heads 2, 2, ... And the carriage 4a stand by at the home position 7.
The home position 7 has a plurality of moisturizing caps 71, 7
1, ... are provided. These multiple moisturizing caps 7
.. are provided in the same number as the recording heads 2 mounted on the carriage 4a. Each moisturizing cap 71
Covers the lower part of each recording head 2
The ink has a size and shape corresponding to the lower part of the recording head 2 and retains the ink of each recording head 2. When the plurality of recording heads 2, 2, ... And the carriage 4a are in the standby state, the carriage 4a is located at the home position 7, each recording head 2 is covered by each moisturizing cap 71, and each recording is performed. The ink relating to the head 2 is kept moist. As a result, ink droplets can be favorably ejected from each recording head 2 during the recording operation.

Next, the structure of each of the above sub tanks 3 will be described in more detail with reference to FIG. FIG. 4A is a vertical cross-sectional view of each sub-tank 3, and FIG. 4B is FIG.
3 is a cross-sectional view taken along line (I)-(I) in FIG. The configuration of each sub-tank 3 described below is basically common to all the sub-tanks 3, 3, ... Of the plurality of sub-tanks 3, 3 ,. explain.

The sub-tank 3 is a member formed of a heat transfer member, which will be described later, in a substantially box shape, and has two partition walls 3 for partitioning the interior of the sub-tank 3 into three liquid chambers 3a, 3b, 3c.
1, 32, the heater wire 34 arranged around each liquid chamber 3a, 3b, 3c, and the remaining amount detection for detecting the amount of ink remaining in the liquid chamber 3c (hereinafter referred to as "ink remaining amount"). A sensor 35 and a temperature sensor 36 for detecting the temperature of the ink in the liquid chamber 3c are provided.

The heater wire 34 is used for each liquid chamber 3a, 3b, 3c.
A member that heats the ink inside the two partition walls 31,
The sub-tank 3 including 32 is arranged inside the heat transfer member that constitutes the casing. Specifically, the heater wire 34 extends to the left and right sides and the lower side of each liquid chamber 3a, 3b, 3c, and as a whole in longitudinal section (see FIG. 4A), each liquid chamber 3
They are arranged in a comb shape with a, 3b, and 3c interposed therebetween. The heat transfer member is intended to efficiently transfer heat from the heater wire 34 to the ink in each of the liquid chambers 3a, 3b, 3c, and is therefore made of a material having a high thermal conductivity. As the material of the heat transfer member, for example, a metal such as aluminum, iron, nickel, copper or stainless steel, or a ceramic such as SiC, BeO or AlN is preferable.

In the vicinity of the lower part of the liquid chamber 3a, an inflow port 3d for introducing the ink from the main tank 8 via the ink supply member 10 and the like is provided. At the inlet 3d,
An ink valve 37 for adjusting the supply of ink from the main tank 8 is provided. The ink valve 37 is open when ink is supplied to the sub tank 3, and is normally closed in other cases. On the other hand, in the vicinity of the lower portion of the liquid chamber 3c, the ink stored in the liquid chamber 3c is recorded by the recording head 2
An outlet 3e is provided for flowing out to.

As described above, the inside of the sub tank 3 is divided into three liquid chambers 3a, 3b and 3c by the two partition walls 31 and 32. However, the partition wall 31 which divides the liquid chambers 3a and 3b is It is configured to be higher than the partition wall 32 that partitions the chamber 3b and the liquid chamber 3c (see FIG. 4A). Each liquid chamber 3a,
The bottom areas of 3b and 3c are substantially the same in all liquid chambers (see FIG. 4 (b)). Therefore, each liquid chamber 3a, 3b, 3c
In the storage capacity of ink, the liquid chamber 3a has the largest capacity, the liquid chamber 3b has the second largest capacity, and the liquid chamber 3c has the smallest capacity.

Furthermore, since the height of the partition wall 31 is higher than that of the partition wall 32, when ink is supplied from the inflow port 3d,
The ink stored in the liquid chamber 3a exceeds the partition wall 31 and overflows (overflows) into the liquid chamber 3b, and the ink stored in the liquid chamber 3b overflows the partition wall 32 into the liquid chamber 3c. That is, the ink flowing into the sub tank 3 overflows stepwise from the liquid chamber 3a to the liquid chamber 3b to the liquid chamber 3c, and is temporarily stored in each of the liquid chambers 3a, 3b, 3c in the sub tank 3. It Then, the ink stored in the liquid chamber 3c finally flows out from the outlet 3e to the recording head 2 communicating with the sub tank 3.

The remaining amount detecting sensor 35 detects the remaining amount of ink as described above, and as shown in FIG.
It is installed near the liquid chamber 3c. This remaining amount detection sensor 3
As 5, the liquid level sensor that detects the liquid level of the ink remaining in the liquid chamber 3c can be applied. The liquid level sensor includes a detection unit 35a that is fully covered with a material such as fluororesin and extends into the liquid chamber 3c, and a light emitting element and a light receiving element (not shown) mounted on the detection unit 35a. Using the difference in the refractive index between the fluororesin and air and the difference in the refractive index between the fluororesin and the liquid (ink), it is detected how much light emitted from the light emitting element returns to the light receiving element. The liquid level of the ink remaining in the liquid chamber 3c is detected. That is, the remaining ink level is detected by detecting the liquid level of the ink with this liquid level sensor. The remaining amount detection sensor 35 is connected to a control device 20 (see FIG. 5) described later, and a detection signal from the remaining amount detection sensor 35 is output to the control device 20.

The temperature sensor 36 is a contact type sensor composed of a thermistor, a thermocouple or the like, and is installed near the liquid chamber 3c as shown in FIG. 4 (b). The temperature sensor 36 detects the temperature of the ink stored in the liquid chamber 3c. The temperature sensor 36, like the remaining amount detection sensor 35, is connected to the control device 20 (see FIG. 5) described later, and the detection signal from the temperature sensor 36 is output to the control device 20.

Next, the configuration of the control device 20 will be described with reference to FIG. FIG. 5 is a block diagram showing a relationship between the control device 20 and members related to the control device 20. As shown in FIG. 5, the control device 20 has, as its basic configuration, a ROM 21 for storing a control program for preliminarily controlling the operation of each member of the printer 1 and data used in the control program, and a control program. A CPU 22 that performs various processes based on the data, and a RAM 23 that stores the data read from the ROM 21 and the data calculated by the CPU 22 based on the control program are provided.

A residual detection sensor 35 for detecting the remaining amount of ink and a temperature sensor 36 for detecting the temperature of the ink in the liquid chamber 3c are connected to the CPU 22 via an interface (hereinafter referred to as "I / F") 24. Has been done. CPU2
2 receives a detection signal from the residual detection sensor 35 and the temperature sensor 36, and performs control based on this detection signal.
A drive circuit 26 that drives the heater wire 34 is connected to the CPU 22 via the I / F 25. CPU
22 outputs a control signal for driving the heater wire 34 to the drive circuit 26 to control the heating of the heater wire 34 and control the temperature of the ink in the sub tank 3 (particularly in the liquid chamber 3c).

Next, the operation of each member during the recording operation of the printer 1 having the above configuration will be described. During the recording operation of the printer 1, the feeding mechanism and the platen 1
By operating the first fan, the recording medium 99 is intermittently fed in the sub-scanning direction B while being held by the platen 11 in a suctioned manner. Here, when the recording medium 99 stops, the carriage mechanism 4 operates so that the carriage 4a moves directly above the recording medium 99 in the main scanning direction A. Then, while the carriage 4 a is moving right above the recording medium 99, ink droplets are ejected from each recording head 2 toward the recording medium 99. The ejected ink droplets land on the recording medium 99. Then, the recording medium 99
The area where the ink droplet has landed passes directly below the light source of the irradiation unit. At this time, light is emitted from the light source, and the ink droplets that have landed on the recording medium 99 are cured. Then, the printer 1 repeats the above-described operation so that desired images are sequentially recorded on the recording medium 99.

Here, when the printer 1 repeats the above-described operation, the amount of ink in each sub-tank 3 is controlled while each residual detection sensor 35 detects the amount of ink remaining in each sub-tank 3. That is, the plurality of sub-tanks 3, 3,
Describing an arbitrary sub-tank 3 of the ... As an example, when the liquid level of the ink stored in the liquid chamber 3c falls below a preset liquid level set value, the residual detection sensor 35 detects the control device 20. A signal is input, and the CPU 22 performs processing for opening the ink valve 37 based on this detection signal. In this case, the ink valve 37 is opened and the ink flows from the main tank 8 into the sub tank 3. Specifically, the ink in the liquid chamber 3a overflows into the liquid chamber 3b, the ink in the liquid chamber 3b overflows into the liquid chamber 3c, and the ink in the liquid chamber 3c flows out into the recording head 2.

When the remaining amount of ink exceeds the required amount,
A detection signal indicating that the required amount has been reached is input to the control device 20 from the residual detection sensor 35, and based on this detection signal, the CPU
22 performs a process of closing the ink valve 37. In this case, the ink valve 37 is closed and the main tank 8 to the sub tank 3
Ink supply to the printer is stopped. In this way, the amount of ink in each sub tank 3 is controlled.

Further, when the printer 1 repeats the above-mentioned operation, each temperature sensor 36 causes the liquid chamber 3c of each sub-tank 3 to operate.
The temperature of the ink in each liquid chamber 3c is controlled while detecting the temperature of the ink inside. That is, when an arbitrary sub-tank 3 of the plurality of sub-tanks 3, 3, ... Is described as an example, the temperature of the ink in the liquid chamber 3c detected by the temperature sensor 36 falls below the lower limit value of the preset temperature range. In that case, a detection signal is input from the temperature sensor 36 to the control device 20, and the CPU 22 performs a process of driving the heater wire 34 based on the detection signal. In this case, the heater wire 34 is heated and each liquid chamber 3 in the sub tank 3 is heated.
a, 3b, 3c are heated, and the ink in each liquid chamber 3a, 3b, 3c is heated.

When the temperature of the ink in the liquid chamber 3c detected by the temperature sensor 36 exceeds the upper limit value of the set temperature range, the temperature sensor 36 outputs a detection signal indicating that the temperature of the ink exceeds a predetermined temperature. 20. The CPU 22 performs a process of stopping the heating of the heater wire 34 based on this detection signal. In this case, the heating of the heater wire 34 is stopped. In this way, the liquid chamber 3 in each sub tank 3
The temperature of the ink of c is controlled.

The “set temperature (T)” relating to the ink temperature control is 30 ° C. ≦ (set temperature T) ≦ 15.
It is preferably 0 ° C., and 40 ° C. ≦ (set temperature T) ≦
More preferably, it is 100 ° C. If the set temperature T is set within this range, the ink can be supplied to the recording head 2 in a state where the viscosity of the ink is lowered, so that the ejection of ink droplets from the recording head 2 can be stabilized. The set temperature T is (set temperature T) ≦ 30 ° C. or 15
When 0 ° C. ≦ (set temperature T), each recording head 2
It is not preferable because it becomes difficult to eject ink droplets from the ink.

Further, since the ink according to the present embodiment generally has a higher viscosity than the water-based ink, the fluctuation range of viscosity due to temperature fluctuation is large. Here, since the fluctuation of the viscosity of the ink directly affects the size of the ink droplet and the ejection speed of the ink droplet as it is, and the image quality is deteriorated, the temperature of the ink in each sub-tank 3 (particularly, each liquid chamber 3c) can be controlled. Only need to keep constant. Therefore, the control range (temperature range) for the set temperature T is preferably controlled to (set temperature T) ± 5 ° C, more preferably (set temperature T) ± 2 ° C, and set to (set temperature T). ) It is more preferable to control to ± 1 ° C.

As described above, in the printer 1 according to the present embodiment,
During the recording operation, the liquid chamber 3c in each sub tank 3
The temperature of the ink inside the liquid chamber 3c is controlled while controlling the amount of ink inside. As a result, even during the recording operation, the amount of ink in the liquid chambers 3c in each sub-tank 3 can be maintained at a substantially predetermined amount, and the temperature of the ink in the liquid chambers 3c in each sub-tank 3 also becomes approximately a predetermined temperature. Can be kept. Here, the ink that has flowed into each sub-tank 3 flows through each sub-tank 3 while gradually approaching the set temperature each time it passes through each liquid chamber 3a, 3b, 3c, and the liquid chamber 3c located at the most downstream side in the flow direction. In, the state is closest to the set temperature. Then, the ink that has accumulated in the liquid chamber 3c flows out from the liquid chamber 3c of each sub-tank 3 to each recording head 2 while being close to the set temperature.

As a result, the temperature of the ink flowing out from the liquid chamber 3c of each sub tank 3 to each recording head 2 can always be stabilized. In other words, the ink can be supplied from each sub tank 3 to each recording head 2 in a state where the viscosity is stabilized. In this case, the viscosity of the ink ejected from each recording head 2 can always be maintained in a stable state with almost no fluctuation in viscosity, and the ejection accuracy of the ink droplet ejected from each recording head 2 can be improved.

Further, in the printer 1 according to this embodiment,
The inside of each sub-tank 3 is divided into three liquid chambers 3a, 3b, 3c by two partition walls 31, 32, and each partition wall 31,
With a simple configuration in which the height of 32 is lowered toward the downstream in the ink flow direction in each sub-tank 3, the ink that has flowed into each sub-tank 3 is moved from the most upstream liquid chamber 3a to the most downstream liquid chamber 3b. Can be supplied to the liquid chamber 3c by overflowing into the liquid chamber 3c.

The present invention is not limited to the above-described embodiment, and within the scope of the gist of the present invention,
Various improvements and design changes may be made. For example,
It is possible to modify the configuration of each sub-tank 3 according to the above embodiment. FIG. 6 shows a modification of each sub-tank 3 according to the above embodiment, and FIG. 7 shows a modification of each sub-tank 3 shown in FIG. 6A is a vertical cross-sectional view of each sub-tank 3, and FIG. 6B is a cross-sectional view of (I) in FIG.
It is a cross-sectional view taken along the line I)-(II). Figure 7 (a)
Is a vertical sectional view of each sub-tank 3, and FIG.
It is a cross-sectional view taken along the line (III)-(III) in (a). In the following description, the same members as those in the above-described embodiment shown in FIG. 4 are denoted by the same reference numerals in FIGS. 6 and 7, and the members have the same configuration as that shown in FIG. The detailed description of is omitted.

In each sub-tank 3 shown in FIG.
As shown in (b), a heater wire 38 is arranged around each liquid chamber 3a, 3b, 3c for each liquid chamber 3a, 3b, 3c.
Specifically, each heater wire 38 is connected to each liquid chamber 3a, 3b, 3c.
To the front and rear sides and to the lower side, and are arranged in a U-shape in a vertical cross-section (not shown). In addition, each heater wire 3
Reference numeral 8 is connected to the CPU 22 of the control device 20 via an I / F 25 and a drive circuit (not shown).

Further, in each sub-tank 3 shown in FIG. 6, as shown in FIG. 6 (b), the temperature sensor 36 has the liquid chambers 3a, 3a.
It is provided for each of b and 3c. Each temperature sensor 36 detects the temperature of the ink stored in each liquid chamber 3a, 3b, 3c. Each temperature sensor 36 is connected to the CPU 22 of the control device 20 via the I / F 24 or the like.

Then, when the printer 1 repeats the recording operation as shown in the above-described embodiment, in each sub-tank 3, the heating of each heater wire 38 is performed based on the detection result detected by each temperature sensor 36. Control is performed for each of 3a, 3b, and 3c. That is, each temperature sensor 36 causes each liquid chamber 3a, 3
The temperatures of the inks in b and 3c are respectively detected, and based on the detection signals detected by the temperature sensors 36, the CPU 22 of the control device 20 performs a process of heating the heater wires 38. When configured in this way, the liquid chambers 3a, 3b, 3
The ink stored in c approaches the set temperature in each of the liquid chambers 3a, 3b, 3c.

The set temperature range for controlling the temperature of the ink in each of the liquid chambers 3a, 3b, 3c is within the range of all the liquid chambers 3a, 3c.
b, 3c may be the same, or liquid chambers 3a, 3c
It may be different for b and 3c. When the set temperature range is made different for each of the liquid chambers 3a, 3b, 3c, the control accuracy of the heating of each heater wire 38 by the control device 20 is set so that the downstream liquid chamber in the ink circulation direction in each sub-tank 3. It is preferable to increase the value. For example, the liquid chamber 3c
The set temperature range for liquid chamber 3b is set to be the narrowest, the set temperature range for liquid chamber 3b is set to be narrower next, and the set temperature range for liquid chamber 3a is set to be widest. In this case, the liquid chamber 3
The temperature of the ink stored in c can be maintained in the most stable state with less temperature fluctuation, and the ink can be supplied from each sub tank 3 to each recording head 2 in a state where the viscosity is more stable.

In each sub-tank 3 shown in FIG. 7, the distance between the liquid chamber 3b and the heater wire 38b is larger than the distance between the liquid chamber 3a and the heater wire 38a, as shown in FIG. 7 (b).
The distance between the liquid chamber 3c and the heater wire 38c is larger than the distance between the liquid chamber 3b and the heater wire 38b. That is, in each sub-tank 3, the heater wire 3 is located closer to the liquid chamber provided downstream in the circulation direction of the ink flowing through the liquid chambers 3a, 3b, 3c.
The distance from 8 is getting bigger. In this case, since the amount of heat conducted from the heater wire 38 is smaller in the downstream liquid chamber,
The ink in the downstream liquid chamber is less likely to be affected by the heat from the heater wire 38. At this time, the temperature fluctuation range becomes smaller as the ink in the downstream liquid chamber becomes smaller. Thereby, each liquid chamber 3a, 3
It is possible to further stabilize the viscosity of the ink in the liquid chamber 3c among b and 3c, and further to supply the ink from each sub tank 3 to each recording head 2 in a state where the viscosity of the ink is further stabilized.

In addition, in each sub-tank 3 shown in FIGS. 4, 6 and 7 according to this embodiment, two partition walls 3 are used.
Although three liquid chambers 3a, 3b, 3c are provided by 1, 32, the number of liquid chambers is not limited to three. That is, the number of liquid chambers may be two or three or more. Moreover, it is not necessary to make all the liquid chambers of the sub-tanks 3 the same in size, and the sizes of the liquid chambers can be appropriately changed. Further, regarding each partition wall 31 and 32 of each sub-tank 3 according to the present embodiment, each partition wall 3
Although the height of 1, 32 is set to be lower toward the downstream side in the ink circulation direction in each sub-tank 3,
The heights of the partition walls 31 and 32 are the same and the partition walls 31 and 3 are the same.
It is also possible to provide a circulation hole in 2 so that the ink can flow between the liquid chambers 3a, 3b, 3c.

Further, each recording head 2 according to the present embodiment
Also, it is preferable that each sub-tank 3 is thermally insulated or insulated so as not to be affected by the temperature from the printer 1 main body or the outside air. In order to shorten the start-up time of the printer 1 required for heating or reduce the loss of thermal energy, heat insulation with members other than each recording head 2 and each sub-tank 3 is performed, and each recording head 2 and each sub-tank 3 is It is preferable to cover with a member having a small heat capacity.

[0081]

According to the present invention, highly viscous ink can be supplied from the sub tank to the recording head while the viscosity is stabilized.

[Brief description of drawings]

FIG. 1 is a perspective view showing an inkjet printer according to this embodiment.

FIG. 2A is a sectional view showing the recording head according to the present embodiment, and FIG. 2B is an enlarged view taken along line (IV)-(IV) of FIG. 2A.

FIG. 3 is an exploded perspective view showing the recording head.

FIG. 4A is a vertical cross-sectional view of the sub-tank according to the present embodiment, and FIG. 4B is a cross-sectional view taken along the line (I)-(I) in FIG. 4A.

FIG. 5 is a block diagram showing a configuration of a control device according to the present embodiment.

6 (a) is a vertical cross-sectional view of a modified example of the sub-tank, and FIG. 6 (b) is a cross-sectional view taken along line (II)-(II) of FIG. 6 (a).

7 (a) is a vertical sectional view of a modified example of the sub-tank, and FIG. 7 (b) is a horizontal sectional view taken along line (III)-(III) in FIG. 7 (a).

[Explanation of symbols]

A main scanning direction B Sub-scanning direction 1 inkjet printer 2 recording head 3 sub tank 3a, 3b, 3c liquid chamber 3d inlet 3e Outlet 31, 32 partition walls 34, 38 heater wire (heating means) 35 Remaining amount detection sensor 36 Temperature sensor (detection means) 4 Carriage mechanism 4a carriage 4b guide member 6 Maintenance unit 7 Home position 8 Main tank (ink tank) 9 Pressurizing pump 10 Ink supply member 11 Platen 20 Control device (control means) 21 ROM 22 CPU 23 RAM 99 recording media

Claims (6)

[Claims] 1. An ink tank for storing high-viscosity ink whose viscosity decreases with temperature rise, a recording head for ejecting the high-viscosity ink onto a recording medium, and the high-pressure ink supplied from the ink tank to the recording head. A sub-tank having two or more liquid chambers capable of temporarily storing viscous ink, heating means for heating the high-viscosity ink stored in the sub-tank, and detecting the temperature of the high-viscosity ink stored in the sub-tank And a control unit that controls the heating unit so that the temperature of the high-viscosity ink stored in the sub-tank becomes a preset temperature based on the detection result of the detection unit, The high-viscosity ink that has flowed from the ink tank to the sub-tank sequentially flows through each liquid chamber of the sub-tank and flows out to the recording head. Inkjet printer characterized by. 2. The ink jet printer according to claim 1, wherein the detection means and the heating means are provided for each liquid chamber, and the control means heats the heating means based on a detection result of each detection means. An ink jet printer characterized by controlling for each liquid chamber. 3. The ink jet printer according to claim 2, wherein the control unit controls the heating of the liquid chamber on the downstream side in the circulation direction of the high-viscosity ink with higher accuracy than the heating of the liquid chamber on the upstream side. An inkjet printer characterized in that. 4. The ink jet printer according to claim 2, wherein the liquid chamber on the downstream side in the flow direction of the highly viscous ink has a smaller amount of heat conducted from the heating means than the liquid chamber on the upstream side. Inkjet printer characterized by. 5. The inkjet printer according to any one of claims 1 to 4, wherein each liquid chamber of the sub tank is partitioned by a plurality of partition walls having different heights, and the height of each partition wall is the An ink jet printer characterized in that it becomes lower as it goes downstream in the flow direction of high-viscosity ink. 6. The inkjet printer according to claim 1, wherein the highly viscous ink is an ink that is cured by being irradiated with light.