JP2003220702A - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet printer capable of stabilizing image quality of a recorded image. <P>SOLUTION: This inkjet printer forms an image on a recording medium by ejecting, from an ink ejection nozzle, ink having a high viscosity by lowering the viscosity of the ink in accordance with temperature rise. The inkjet printer is equipped with a supply passage for supplying the high-viscosity ink to the ink ejection nozzle. The supply passage has a supply passage forming member through which the high-viscosity ink flows. The supply passage consists of two or more layers including an inner side layer formed to surround the high viscosity ink and a layer formed at the outer side of the inner side layer. <P>COPYRIGHT: (C)2003,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.

[0002]

2. Description of the Related Art An ink jet printer supplies ink to a recording head from an ink storage section through a supply path and ejects the supplied ink toward a recording medium such as paper.
While permeating or fixing the ink on this recording medium,
An image is formed on the recording medium by moving the recording head on the recording medium.

When a high-viscosity ink is used as the ink in the above-mentioned ink jet printer, there is an advantage that the ink does not bleed onto the recording medium and clear printing is possible. However, the high-viscosity ink has high viscosity at low temperature and high temperature. Since the viscosity is low such that the viscosity is low depending on the conditions such as the temperature, the quality of the recorded image is not stable and the quality is deteriorated due to the variation of the viscosity of the ink. For example, if high-viscosity ink is ejected as it is, pressure loss will increase inside the supply path, ink cannot be supplied to the print head well, and if the pressure loss exceeds a specified value, nozzle shortage etc. will occur and ink ejection This causes variations in the diameter of the droplet formed on the recording medium, and especially in a recording head or the like with a weak ink ejection force, the ejection speed of the ejected ink droplets fluctuates, causing the recording head to move. And the timing at which the ink droplets adhere to the recording medium may be different.

[0004]

Therefore, an ink storage portion, a supply path, a recording head, etc. (hereinafter referred to as an ink supply system)
It is conceivable to reduce the pressure loss and stabilize the ink supply to the recording head by heating the ink to reduce the viscosity of the high-viscosity ink. However, in order to stabilize the supply of ink to the recording head, it is necessary to make the viscosity of the ink substantially uniform by making the temperature of the ink supply system substantially uniform. That is, if the ink supply system is simply heated, the temperature of the ink supply system may become non-uniform, and the viscosity of the ink in the ink supply system may become non-uniform. This causes instability of the image quality of the image.

An object of the present invention is to provide an ink jet printer capable of stabilizing the quality of recorded images.

[0006]

The invention according to claim 1 is
By lowering the viscosity of highly viscous ink that becomes less viscous as the temperature rises and ejecting it from the ink ejection port to the recording medium,
An inkjet printer for forming an image on the recording medium, comprising: a supply path for supplying highly viscous ink to the ink ejection port, wherein the supply path comprises a supply path forming member through which the highly viscous ink flows, The supply path forming member is
It is characterized in that it is composed of two or more layers including an inner layer formed so as to surround the high-viscosity ink and a layer formed outside the inner layer.

Here, the highly viscous ink is preferably a liquid having a viscosity at 30 ° C. of 50 to 3000 mPa · s. More preferably, it is 50 to 1000 mPa · s.
And more preferably 100 to 500 mPa · s. At 50 mPa · s or less, bleeding is likely to occur, and clear printing cannot be performed. Moreover, at 3000 mPa · s or more,
The smoothness of image quality is lost. Furthermore, the viscosity at 60 ° C is 3
It is preferably a liquid of ˜30 mPa · s. 3 mP
If it is less than a · s, a problem may occur in high-speed ejection, and if it exceeds 30 mPa · s, the ejection property may deteriorate. When ejected from a recording head composed of a piezo element, the viscosity is 3 to 30 mPa ·
s liquid is preferred.

According to the first aspect of the invention, the supply path is
A two-layer structure including a supply path forming member through which highly viscous ink flows, the supply path forming member including an inner layer formed so as to surround the highly viscous ink and a layer formed outside the inner layer. Since it is configured as described above, the temperature distribution in the supply passage is less likely to change with time as compared with the case where the supply passage is configured by a single layer,
It can be designed to facilitate temperature control. For example, when the layer in contact with the highly viscous ink is made of a member made of a material having higher thermal conductivity than the layer not in contact, the layer in contact can be efficiently heated when the supply path is heated. At the same time, the temperature inside the supply path can be kept substantially uniform by the layer that does not come into contact with the temperature. As a result, the viscosity of the high-viscosity ink in the supply path can be made substantially uniform, and the viscosity can be kept optimum for ink ejection. Therefore, stable ink ejection can be performed, and the image quality of a recorded image can be stabilized.

According to a second aspect of the present invention, in the ink jet printer according to the first aspect, the supply path forming member is a layer formed outside the inner layer rather than an inner member forming the inner layer. It is characterized in that the external member constituting the is made of a material having a lower thermal conductivity.

According to the invention described in claim 2, it is possible to obtain the same effect as that of the invention described in claim 1.

The invention according to claim 3 is the invention according to claim 1 or 2.
In the inkjet printer described above, the supply path forming member is composed of a heating member provided with a heating means for heating the inner layer, and the layer formed on the outer side of the inner layer is a highly viscous ink. It is characterized in that it is composed of a heat insulating member for keeping heat.

Here, the heating member may have any structure as long as it can heat the highly viscous ink. For example, the heating member is a member that surrounds the highly viscous ink, and the member that surrounds this ink heats the ink. Alternatively, the heating member may include a member that surrounds the ink and a member that heats the member that surrounds the ink, and the heating member may heat the high-viscosity ink via the member that surrounds the ink. Further, the heat insulating member is preferably a member having a heat resistant temperature of 100 ° C. or higher, and more preferably 200 ° C. or higher. As the constituent material of the heat insulating member, for example, silicon, fluororubber,
Examples thereof include Teflon (registered trademark).

According to the third aspect of the present invention, in the supply path forming member, the inner layer is composed of a heating member provided with a heat generating means for heating the highly viscous ink, and the layer formed outside the inner layer. Is composed of a heat insulating member that keeps the high-viscosity ink warm, so the high-viscosity ink heated by the heating member is
It is difficult for the heat insulating member to be affected by the surrounding heat, and the temperature distribution in the supply path is unlikely to change with time. Therefore, it is possible to easily control the temperature in the supply path and reduce the power required for heating the ink.

According to a fourth aspect of the invention, in the ink jet printer according to the third aspect, the heating member forming the inner layer is formed in contact with the highly viscous ink, and the heat conduction is higher than that of the heat insulating member. It is characterized by comprising a heat conducting member made of a highly conductive material, and a heater arranged in contact with the heat conducting member to serve as the heat generating means.

Here, the heat conducting member is preferably a member having a heat conductivity of 0.2 cal / cm · s · ° C. or higher. The constituent material of the heat conducting member is, for example, copper, aluminum or stainless steel (SUS). ) And the like.

According to the fourth aspect of the present invention, the heating member forming the inner layer is formed in contact with the highly viscous ink and is made of a material having a higher thermal conductivity than the heat insulating member. Since the conductive member and the heater that is disposed in contact with the heat conductive member and serves as a heat generating means are provided, the heater can heat the highly viscous ink via the heat conductive member, and the highly viscous ink is directly heated. As compared with the case of performing the above, the highly viscous ink in the supply path can be heated substantially uniformly.

According to a fifth aspect of the present invention, there is provided the ink jet printer according to any one of the first to fourth aspects,
An ink storage unit for storing high-viscosity ink, a recording head having the ink ejection port, and a supply pipe for supplying high-viscosity ink from the ink storage unit to the recording head,
It is characterized in that the supply passage is composed of the ink containing portion, the supply pipe, and an ink passage provided in the recording head.

According to the fifth aspect of the invention, since the supply passage is composed of the ink containing portion, the supply pipe, and the ink flow path provided in the recording head, the ink is contained in the ink containing portion. The high-viscosity ink is supplied to the recording head through the supply pipe, and the temperature of the high-viscosity ink can be adjusted to be optimal for ink ejection in the recording head until the ink is ejected from the ink ejection port.

According to a sixth aspect of the invention, there is provided the ink jet printer according to any one of the first to fifth aspects,
The high-viscosity ink is characterized in that it contains UV ink that is cured by being irradiated with ultraviolet rays.

According to the sixth aspect of the present invention, the ink is cured by UV (Ultra Vi).
Since the ink contains olet) ink, the same effect as that of the invention according to any one of claims 1 to 5 can be obtained even when the UV ink is used. In this way, if UV ink is used for printing, it will
Since the V ink hardens, the printed image can be maintained for a long time without being erased, and the quality of the printed image by the inkjet printer can be improved. further,
When UV ink is used for printing, even if the recording medium is not a recording medium having good ink absorbability (for example, paper), printing can be performed even if the recording medium does not have ink absorbability or has low ink absorbency. It can be carried out.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

The ink jet printer exemplified in this embodiment ejects a highly viscous UV ink (hereinafter abbreviated as ink), which becomes less viscous as the temperature rises and hardens when irradiated with ultraviolet rays, to a recording medium. Then, the ink is landed and printed. This inkjet printer 100
For example, as shown in FIG. 1, a conveying unit (not shown) that conveys a sheet-shaped recording medium P such as paper to the front during printing, a printing unit 1 that prints on the recording medium P, and a plurality of colors A carriage 2 on which the printing unit 1 is mounted, a main tank 3 for storing ink to be supplied to the printing unit 1, a supply pipe 4 for supplying ink from the main tank 3 to the printing unit 1, and maintenance for performing maintenance on the printing unit 1. Unit 5, carriage 2 for printing or maintenance
Is provided with a guide rail 6 that guides the vehicle along the horizontal direction (arrow A), a home position 7 that serves as a standby position for the carriage 2, and a control unit (not shown) that controls these units.

At the time of printing, the conveying means conveys the recording medium P on the printing area at the same timing as the operation of the carriage 2, and when the printing is completed, the recording medium P is moved downward from the printing area C (arrow). Transport to B). The upper surface of the recording medium P is the printing surface.

As shown in FIGS. 2 to 5, the printing section 1 ejects a sub-tank (ink storage section) 11 for storing ink flowing from the supply pipe 4 and the ink on the recording medium P in a low viscosity state. Ejection opening (ink ejection opening) 124a
And a supply pipe 13 that supplies ink from the sub-tank 11 to the recording head 12.

These sub tank 11, recording head 12,
The supply pipe 13 forms an ink supply path (supply path) 200 from the inside of the sub tank 11 to the ejection port 124a, and is provided with a supply path forming member 201 through which ink flows. The supply path forming member 201 includes an inner layer (hereinafter referred to as an inner layer) 210 formed so as to surround the ink,
The inner layer 210 and a layer (hereinafter, referred to as an outer layer) 220 formed on the outer side of the inner layer 210 form two layers. Inner layer 21
0 is formed by, for example, heating wire (sub-tank heating wire 112, recording head heating wire 127, supply tube heating wire 132; heater, heating means) that heats the ink, and the inner surface in contact with the ink, and the heating wire generates heat. The heating member (internal member) 211 includes a heat conducting member (sub-tank heat conducting member 111, recording head heat conducting member 126, supply pipe heat conducting member 131) that is heated by heating the ink. There is. The heat conducting member has higher heat conductivity than the heat insulating member (described later) 221 and has a heat conductivity of 0.2c.
It is composed of, for example, copper or the like having a temperature of al / cm · s · ° C. or higher. Further, a heating wire is arranged in contact with the heat conducting member. On the other hand, the outer layer 220 is, for example, a heat insulating member (sub-tank heat insulating member 11) that shields the surrounding heat to keep the ink warm.
3, recording head heat insulating member 128, supply pipe heat insulating member 13
3; external member) 221. The heat insulating member 221 has lower thermal conductivity than the heating member 211 and is made of, for example, silicon having a heat resistant temperature of 100 ° C. or higher. The heat resistant temperature of the heat insulating member 221 is more preferably 200 ° C. or higher. The structures of the sub tank 11, the recording head 12, and the supply pipe 13 will be specifically described below.

The sub-tank 11 has, for example, a sub-tank heat-conducting member 111 formed in the shape of a substantially rectangular parallelepiped having an internal space and each surface having a predetermined thickness, and an outer surface of the sub-tank heat-conducting member 111. It is wound in an annular shape, and a plurality of pieces (for example, 5 pieces;
(See (b)) Sub-tank heating wire 112 fixed side by side
And a sub-tank heat-insulating member 113 which is in contact with the sub-tank heating wire 112 and the sub-tank heat conducting member 111 on the inner surface and which is formed, for example, in a case shape having a substantially rectangular parallelepiped shape. The sub-tank heat insulating member 113 is formed such that its outer surface is parallel to the outer surface (inner surface) of the sub-tank heat conducting member 111. The internal space is an ink storage unit 114 for storing the ink poured from the supply pipe 4, and is formed, for example, in a substantially rectangular parallelepiped shape having a surface parallel to the surface of the subtank heat conductive member 111.

The sub-tank 11 is also provided with an atmosphere communication port 115, an ink inflow port 116, and an ink outflow port 117, which are provided so as to penetrate the sub-tank heat insulating member 113 and the sub-tank heat conducting member 111, for example. The atmosphere communication port 115 is provided, for example, on the upper side of the sub-tank 11 to prevent the internal pressure from changing during ink ejection. The ink inflow port 116 is provided, for example, on one side of the sub-tank 11 (for example, the right side in FIG. 3B), and extends from the supply pipe 4 to the ink storage unit 1.
It is for inflowing the ink into 14. The ink outlet 117 is provided, for example, on the other side portion of the sub-tank 11 (for example, the left side in FIG. 3B), and is for discharging the ink stored in the ink storage unit 114 to the supply pipe 13. Is.

The supply pipe 13 has, for example, a supply pipe heat conduction member 131 formed in a substantially cylindrical shape having a predetermined thickness, and a predetermined interval is provided on the outer peripheral surface of the supply pipe heat conduction member 131 along the longitudinal direction. A plurality of (for example, four) fixed supply pipe heating wires 132 are formed, and the supply pipe heating wires 132 and the supply pipe heat conducting members 131 are in contact with each other on the inner surface and are formed in, for example, a substantially cylindrical outer shape along the longitudinal direction thereof. Supply pipe insulation 133
It has and. The internal space serves as an ink supply path from the sub tank 11 to the recording head 12.

The recording head 12 includes a head body 121,
It is provided with a substrate 122 of a drive circuit for the recording head 12 provided in contact with one side of the head body 121 (see FIG. 5). For example, as shown in FIG. 5, the head main body 121 includes a manifold unit 1 that branches ink introduced from the supply pipe 13 into a plurality of channels (described later) 124.
23 and the lower side of the manifold 123,
Ejection means (piezo element) 12 for ejecting ink
0, and a nozzle plate 125 provided so as to cover the lower surface of the ejection means 120 and provided with a plurality of ejection openings 124a.
A recording head heat conducting member 126 formed in a substantially rectangular parallelepiped case shape having a predetermined thickness so as to cover the manifold portion 123 and the ejecting means 120; A plurality of recording head heating wires 12 are fixed along the surface at a predetermined interval.
7, and a recording head heat insulating member 128 which is in contact with the recording head heating wire 127 and the recording head heat conducting member 126 on the inner surface and which is formed, for example, in the shape of a case having a substantially rectangular parallelepiped shape. The recording head heat insulating member 128 is formed so that its outer surface is parallel to the outer surface (inner surface) of the recording head heat conduction member 126. Manifold part 123
Is an internal space formed in a substantially rectangular parallelepiped shape having a surface parallel to the surface of the heat conduction member 126 of the recording head. Further, the channel 124 is a plurality of grooves provided, for example, substantially vertically in the ejection means 120, and the lower end thereof is in communication with the ejection port 124a of the nozzle plate. An ink channel 129 is formed by the channel 124 and the manifold portion 123.

Thus, the sub tank 11 and the supply pipe 1
3 and the ink flow path 129 in the recording head 12 form an ink supply path 200 that supplies ink to the ejection openings 124a.

The printing unit 1 uses the types of ink used in the ink jet printer (Y: yellow, LY: light yellow, M: magenta, LM: light magenta,
C: cyan, LC: light cyan, K: black, L
(K: light black).

For example, as shown in FIG. 1, the carriage 2 repeats the reciprocating movement along the horizontal direction (arrow A) by the guide of the guide rail 6, and the printing unit 1 prints the recording medium P in the printing area C. Move along a plane. Further, the carriage 2 includes a UV light source (not shown) that radiates ultraviolet rays to cure the ink ejected from the printing unit 1.

The main tank 3 is, for example, an ink cartridge or the like which is provided so as to be replaceable. Although the main tank 3 is divided for each color in this embodiment, the main tanks 3 may be integrated.

The supply pipe 4 makes it possible to supply ink from the main tank 3 to the printing unit 1 for each color by connecting the respective main tanks 3 to the corresponding printing units 1. The supply pipe 4 is formed of a flexible member so as to correspond to the movement of the printing unit 1.
Each of the supply pipes 4 is provided with a pressure feed pump 41 that changes the pressure inside the supply pipe 4 and supplies ink from the main tank 3 to the printing unit 1.

The maintenance unit 5 includes the carriage 2
Is provided on one end side of the reciprocating path outside the printing region C, and sucks ink from the ejection port 124a in a state where the lower surface of the nozzle plate 125 (hereinafter referred to as the nozzle surface) is covered and sealed. A suction cap 51, and a blade portion 52 for wiping off the ink remaining on the nozzle surface after the suction cap 51 sucks the ink.
And a blade cleaner portion (not shown) for cleaning the blade portion 52.

The home position 7 is provided at the other end of the path along which the carriage 2 reciprocates. Moisturizing caps 71 for moisturizing the nozzle surface of the recording head 12 are provided in the home position 7 in the same number as the recording head 12, and the nozzle surface of the recording head 12 is covered and hermetically closed while the carriage 2 is on standby. ing.

The control means is a CPU (Central Processing).
Unit), ROM (Read Only Memory), RAM (Random)
m Access Memory), an interface, etc., and controls each component of the inkjet printer 100.

Next, the control and operation of adjusting the temperature of the ink in the sub tank 11, the supply pipe 13, and the recording head 12 by the ink jet printer 100 will be described.

When the power is turned on, the printer stands by until the printing is started. In this state, the sub-tank heating wire 112, the supply pipe heating wire 132, the recording head heating wire 1
By controlling the output of 27, etc., the temperature of the ink in the sub tank 11, the supply pipe 13, and the recording head 12 is made substantially uniform so that the viscosity of the ink is optimal for ink ejection. That is,
The heat of each heating wire is efficiently conducted to the ink through the sub-tank heat conduction member 111, the supply pipe heat conduction member 131, and the recording head heat conduction member 126 to heat the ink. At this time, the inside of the sub tank 11, the supply pipe 13, and the recording head 12 are kept warm by the sub tank heat insulating member 113, the supply pipe heat insulating member 133, and the recording head heat insulating member 128 which are provided so as to cover the respective heat conducting members and heating wires. Then, the temperature of the ink is made substantially uniform. Then, when the temperature of the ink becomes substantially uniform, printing becomes possible. After that, when printing is started, ink is ejected toward the recording medium P from the ejection port 124a. Note that the same control as above is performed while printing is being performed. Therefore, the temperature is adjusted until ink is supplied from the sub tank 11 to the recording head 12 through the supply pipe 13 and discharged from the discharge port 124a.
The viscosity of the ink in the recording head 12 can be optimized for ink ejection.

As described above, according to the ink jet printer 100 of this embodiment, the sub tank 11, the recording head 12, and the supply pipe 13 form the ink supply path 200 for supplying the ink to the ejection port 124a. A supply passage forming member 201 through which ink flows is provided inside, and the supply passage forming member 201 is a heat conducting member formed in contact with ink and having a higher heat conductivity than the heat insulating member 221 and made of, for example, copper. An inner layer 210 composed of a heating wire that is placed in contact with the heat conducting member to heat the ink,
The sub-tank 11, the recording head 12, and the supply pipe 1 are formed by the outer layer 220 that is formed outside the inner layer 210 and is formed of a heat insulating member that keeps the ink warm.
Subtank 1 compared to the case where each of 3 is composed of a single layer
1, the temperature distribution in the recording head 12 and the supply pipe 13 does not easily change over time, and the temperature management becomes easy. That is, when heating each of the sub tank 11, the recording head 12, and the supply pipe 13, the inner layer 210 can be efficiently heated, and
The outer layer 220 can keep the insides of the sub-tank 11, the recording head 12 and the supply pipe 13 warm, and make their temperatures substantially uniform. As a result, the sub tank 11, the recording head 12,
The viscosity of the ink in the supply pipe 13 can be made substantially uniform, and the viscosity can be kept optimum for ink ejection. Therefore, stable ink ejection can be performed, and the image quality of a recorded image can be stabilized. Further, the ink heated by the heating wire is not easily affected by the surrounding heat by the heat insulating member 221, and the sub tank 11, the recording head 12, the supply pipe 13 are
The temperature distribution inside is unlikely to change over time. Therefore, it is possible to reduce the power required for heating the ink. Further, the ink can be heated by the heating wire via the heat conducting member, and compared with the case of directly heating the ink, the sub tank 1
1. The ink in the recording head 12 and the supply pipe 13 can be heated substantially uniformly.

Further, since highly viscous UV ink is used as the recording liquid, it is possible to obtain highly viscous UV ink by irradiating it with ultraviolet rays after printing.
The ink hardens, the printed image cannot be easily erased for a long period of time, and excellent weather resistance can be exhibited even when the printed matter is placed outdoors. That is, the printed image by the inkjet printer 100 is less likely to bleed,
Clear printing can be performed and the quality of the printed image can be improved. Further, when the high-viscosity UV ink is used, even if the recording medium P is not a recording medium having good ink absorbability (for example, paper), it is a recording medium having no ink absorbability or a recording medium having low ink absorbability. Can also be printed. Here, a recording medium having no ink absorbability or a recording medium having low ink absorbability means a recording medium formed of a material having no ink absorbability or a material having low ink absorbability,
Alternatively, it is a recording medium having a surface layer (printing layer) made of a material having no ink absorption or a material having low ink absorption. Examples of the material having no ink absorptivity or the material having a low ink absorptivity include various plastics and metals.

<Modification 1> Modification 1 will be described with reference to FIG. The inkjet printer 100 according to the first modification includes a sub tank 311 including a sub tank heat pipe (heater, heat generating means) 312. That is, the sub-tank heat pipe 312 is formed, for example, in a substantially cylindrical shape having a predetermined thickness, and is arranged substantially vertically in the heat pipe storage portions provided in the swelled portions on the left and right sides of the sub-tank heat conduction member 313. Has been done.
The inside diameter of the heat pipe housing is set to be substantially the same as or slightly larger than the outside diameter of the sub tank heat pipe 312, and the depth thereof is from the upper surface of the sub tank 311 to the sub tank heat pipe. Conductive member 3
The dimension is set to be slightly smaller than the length of the lower surface of 13. The sub tank heat insulating member 315 is provided in contact with the sub tank heat conducting member 313 on its inner surface.

Inkjet printer 1 of the first modification
According to 00, it is possible to obtain the same effect as that of the above embodiment.

In this embodiment, the supply path forming member 201 is composed of two layers, the inner layer 210 and the outer layer 220. However, the present invention is not limited to this. For example, the inner layer 210 and the outer layer 220 may be formed. Any number of layers including two or more layers may be included. Further, although the sub-tank 11 is mounted on the carriage 2, it is not limited to this. For example, the sub-tank 11 may not be mounted on the carriage 2. Further, for example, the ink supply path may be formed from the main tank to the ejection port 124a without the sub tank 11, and in this case, the main tank has the same structure as the sub tank 11 described above.

[0045]

According to the first aspect of the present invention, the supply passage is provided with a supply passage forming member through which the high viscosity ink flows, and the supply passage forming member is formed so as to surround the high viscosity ink. Since it is composed of two or more layers including a layer formed on the outer side and a layer formed on the outer side than the inner layer, the temperature distribution in the supply passage is less likely to change with time as compared with the case where the supply passage is formed of a single layer. , Can be designed to facilitate temperature management. For example, when the layer in contact with the highly viscous ink is made of a member made of a material having higher thermal conductivity than the layer not in contact, the layer in contact can be efficiently heated when the supply path is heated. At the same time, the temperature inside the supply path can be kept substantially uniform by the layer that does not come into contact with the temperature. As a result, the viscosity of the high-viscosity ink in the supply path can be made substantially uniform, and the viscosity can be kept optimum for ink ejection.
Therefore, stable ink ejection can be performed, and the image quality of a recorded image can be stabilized.

According to the third aspect of the present invention, in the supply path forming member, the inner layer is composed of a heating member provided with a heating means for heating the highly viscous ink, and the layer formed outside the inner layer. Is composed of a heat insulating member that keeps the high-viscosity ink warm, so the high-viscosity ink heated by the heating member is
It is difficult for the heat insulating member to be affected by the surrounding heat, and the temperature distribution in the supply path is unlikely to change with time. Therefore, it is possible to easily control the temperature in the supply path and reduce the power required for heating the ink.

According to the fourth aspect of the present invention, the heating member forming the inner layer is formed in contact with the highly viscous ink, and is made of a material having a higher thermal conductivity than the heat insulating member. Since the conductive member and the heater that is disposed in contact with the heat conductive member and serves as a heat generating means are provided, the heater can heat the highly viscous ink via the heat conductive member, and the highly viscous ink is directly heated. As compared with the case of performing the above, the highly viscous ink in the supply path can be heated substantially uniformly.

According to the fifth aspect of the invention, since the supply passage is composed of the ink containing portion, the supply pipe, and the ink flow path provided in the recording head, the ink is contained in the ink containing portion. The high-viscosity ink is supplied to the recording head through the supply pipe, and the temperature of the high-viscosity ink can be adjusted to be optimal for ink ejection in the recording head until the ink is ejected from the ink ejection port.

According to the sixth aspect of the present invention, the ink is UV (Ultra Vi) which is cured by being irradiated with ultraviolet rays.
Since the ink contains olet) ink, the same effect as that of the invention according to any one of claims 1 to 5 can be obtained even when the UV ink is used. In this way, if UV ink is used for printing, it will
Since the V ink hardens, the printed image can be maintained for a long time without being erased, and the quality of the printed image by the inkjet printer can be improved. further,
When UV ink is used for printing, even if the recording medium is not a recording medium having good ink absorbability (for example, paper), printing can be performed even if the recording medium does not have ink absorbability or has low ink absorbency. It can be carried out.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of an inkjet printer illustrated as an embodiment to which the present invention is applied.

FIG. 2 is a perspective view of a main part showing a printing unit included in the inkjet printer of FIG.

FIG. 3 is a cross-sectional view of essential parts showing a sub tank provided in the inkjet printer of FIG.

FIG. 4 is a cross-sectional view of essential parts showing a supply pipe provided in the inkjet printer of FIG.

5 is a cross-sectional view of a main part showing a head body of a recording head included in the inkjet printer of FIG.

6 is a cross-sectional view of a main part showing an example of a sub tank having a structure different from that of the sub tank of FIG.

[Explanation of symbols]

100 inkjet printer 200 ink supply path (supply path) 201 supply path forming member 210 inner layer 211 heating member (inner member) 220 outer layer 221 heat insulating member (external member) 11, 311 sub-tank (ink storage portion, Supply path) 111, 313 Sub tank heat conduction member (heat conduction member) 112 Sub tank heating wire (heating wire, heater,
Heat generating member) 113, 315 Sub tank heat insulating member (heat insulating member) 312 Sub tank heat pipe (heater, heat generating member) 12 Recording head 126 Recording head heat conduction member (heat conduction member) 127 Recording head heating wire (heating wire) 128 Recording head heat insulation Member (heat insulating member) 129 Ink flow path (supply path) 124a Discharge port (ink discharge port) 13 Supply pipe (supply path) 131 Supply pipe Heat conduction member (heat conduction member) 132 Supply pipe Heating wire (heating wire) 133 Supply Pipe heat insulation member (heat insulation member) P Recording medium

Claims (6)

[Claims] 1. An ink jet printer for forming an image on a recording medium by lowering the viscosity of a highly viscous ink which becomes less viscous as the temperature rises and ejecting it from an ink ejection port onto the recording medium. A supply path for supplying the high-viscosity ink to the ejection port is provided, the supply path includes a supply-path forming member through which the high-viscosity ink flows, and the supply-path forming member is formed so as to surround the high-viscosity ink. An inkjet printer comprising two or more layers including an inner layer and a layer formed outside the inner layer. 2. The ink jet printer according to claim 1, wherein the supply path forming member is an external member forming a layer formed outside the inner layer rather than an inner member forming the inner layer. The inkjet printer is characterized in that it is made of a material having a lower thermal conductivity. 3. The ink jet printer according to claim 1, wherein the supply path forming member is a heating member in which the inner layer is provided with a heating means for heating highly viscous ink, An ink jet printer, wherein a layer formed on the outside is composed of a heat insulating member that keeps high-viscosity ink warm. 4. The ink jet printer according to claim 3, wherein the heating member forming the inner layer is formed in contact with the highly viscous ink and is made of a material having a higher thermal conductivity than that of the heat insulating member. And a heater which is arranged in contact with the heat conducting member and serves as the heat generating means. 5. The ink jet printer according to any one of claims 1 to 4, wherein an ink containing section for containing a highly viscous ink, a recording head having the ink ejection port, and the ink containing section to A supply pipe for supplying high-viscosity ink to the recording head is provided, and the supply passage is composed of the ink storage portion, the supply pipe, and an ink flow path provided in the recording head. And inkjet printer. 6. The inkjet printer according to claim 1, wherein the highly viscous ink includes UV ink which is cured by being irradiated with ultraviolet rays. Inkjet printer.