JP2573822B2 - Ink jet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a recording apparatus in which a solid ink is heated and melted at room temperature to form a liquid, and is ejected as a droplet from a nozzle only when necessary. It relates to the configuration of the head.

[Prior Art] Conventionally, a liquid jet recording apparatus that melts into a liquid phase using a wax-based ink is disclosed in JP-A-59-7052, and a solid ink is heated in JP-A-58-208062. An ink jet recording apparatus which melts and discharges the ink as ink droplets is known. As the ink, an ink composition for ink jet is known from JP-A-58-108271.

[Problems to be Solved by the Invention] However, in the related art, the structure of an ink tank or the like that changes the ink from a solid phase to a liquid phase by heating and melting is not known.

In addition, the hot-melt type ink containing the aforementioned wax-based ink and wax as a main component causes a volume shrinkage of about 10 to 20% when the phase changes from a liquid phase to a solid phase,
It causes a decrease in the internal ink pressure and forms countless cavities.
Since the air dissolved in the ink is discharged into this cavity, it is present as a bubble when the state changes from the solid phase to the liquid phase next time. Naturally, this phenomenon occurs in all portions filled with the ink, which is a serious problem that the ink jet printer cannot print.

Therefore, the present invention solves such a problem,
An object of the present invention is to provide an ink jet recording apparatus using a hot melt type ink, which is highly reliable and can be printed in a short time. It is another object of the present invention to provide an ink jet recording apparatus which eliminates ink consumed other than for pixel formation, uses ink efficiently, and has high thermal efficiency.

[Means for Solving the Problems] An inkjet recording apparatus according to the present invention is a hot-melt type inkjet recording apparatus that uses a solid ink by heating and melting at room temperature, wherein the inkjet head is provided with a heating unit for melting the ink. An outer tank provided with a heating means for melting ink, which supplies ink in communication with the head; and an inner tank which is in contact with the outer tank and supplies ink to the outer tank via a filter. An ink recovery unit disposed near the outer tank, for recovering ink discharged from a head and feeding the ink to the inner tank, wherein the outer tank, the inner tank, and the ink recovery unit are provided in the outer tank. The outer tank, the head, and the ink reservoir are formed by a member that can conduct heat from the arranged heating means to such an extent that the ink can be melted. Characterized by comprising a heat insulating structure section around.

[Embodiment] FIG. 1 shows an embodiment of an ink jet recording apparatus to which the present invention is applied. In FIG. 1, reference numeral 1 denotes an axial direction of a platen 3 guided by guide members 2 and 2. The carriage is equipped with a head unit 12 composed of a head 4, an ink tank 5, and a heat insulating structure 11 surrounding them, and is configured to move the head unit 12 in the width direction of the printing paper P. Here, a heat insulating structure 11 described later is not shown for simplicity.

Reference numeral 7 denotes an air valve component including a cap member 71, an actuator 72, and a rotating shaft 73 connecting these components.
Is an ink pressurizing mechanism composed of an air tube member 81, an air pump 82, an actuator 72, and a hollow rotary shaft 83. The air valve component 7 and the ink pressurizing mechanism 8 will be described in detail later.

FIG. 2 is a block diagram showing the configuration of the present invention, and the operation of the present invention will be described based on FIG. In the state before the operation, the ink 10 is filled with the solid phase in the head 4 via the ink tank 5 and the supply path 56, and the ink 10 is heated and melted by using the heating means 9 to operate. At this point,
The liquid ink 10 in the head 4 contains countless bubbles. The bubbles in the ink tank 5 rise and are released to the atmosphere, or they need to be dissolved in the ink 10 to form an ink layer containing no bubbles, and the ink 10 needs to be guided into the head 4. In the present invention, after the ink is melted, the ink valve 63,
The air valve component 7 is closed, and high-pressure air is sent from the ink pressurizing component 8 into the inner tank 52 through the air flow path 65, the ink reservoir 67, and the ink recovery path 66.
The pressure inside the head 4 rises and the pressure propagates to the head 4, the ink 10 in the head 4 is discharged from the nozzle 42, and the inside of the head 4 is filled with the ink 10 containing no bubbles. The discharged ink 10 travels along the tongue 41 and falls into the ink receiver 64.
After the ink pressurization is completed, the ink 10 accumulated in the ink receiver 64 is opened in the ink valve 67 by opening the air valve component 7 and opening the ink valve 63. The ink 10 accumulated in the ink reservoir 67 returns to the inner tank 52 together with the air through the ink recovery path 66 at the next purge, and the dust is removed by the filter 54 to be reused. Hereinafter, each component will be described in detail based on the above-described operation principle.

FIG. 3 is an external view of a head unit 12 which is a characteristic part of the present invention. The head unit 12 is made of glass, photosensitive glass,
An ink flow path is formed of plastic, metal, etc.
An on-demand type head for obtaining more ink droplets; a head 4 in which an electric resistor, a posistor, etc., which generates heat by an external signal, are disposed as ink heating means 9;
Ink tank 5 made of a good heat conductive material such as copper, zinc, iron, alloys thereof, ceramics, etc., and ink recovery unit 6 made of a good heat conductive material such as the same material
A heat insulating structure in which materials with good heat resistance and poor heat conductivity, such as plastics such as fluororesin, polyphenylene sulfide, polyimide, polyacid imide, polysulfone, polyethersulfone, and polyetheretherketone, are arranged around them. 11 and. The head 4 is provided with a projection as a tongue-shaped portion 41 so that the discharged ink easily falls into the ink receiver 64.
The ink discharged from the nozzle 42 does not scatter around and falls into the ink receiver 64.

The ink tank 5 has the structure shown in FIG. 4 and is made of the above-described good heat conductive material in the inner tank 52, and has a mesh formed by knitting a stainless steel thread or a polyamide thread in an opening of one wall surface.
The filter 54 is provided with a micro sieve made of electroformed nickel or a porous material such as ceramics or plastic and having holes of about 200 to 1000 in size. 53 fins are formed on the inner tank 52 and other wall surfaces.
53 has a communication hole 55 at the bottom for allowing the ink 10 to pass through, and is in contact with the outer tank 51. The outer tank 51 is made of the above-mentioned good heat conductive material, and as shown in FIG.
57 are circumscribed. The ink supply chamber 57 has an upward ceiling 58 having an angle of about 5 to 30 degrees, and the bubbles 14 generated when the ink is melted rise and disappear quickly. The ink has a thermal conductivity that is two to three orders of magnitude lower than metal and a specific heat of two.
About 5 times larger than that, it is difficult to heat. Therefore, the area in contact with the good heat conductive material per unit volume of the ink is increased by the fin 53, and the required amount of the ink can be reduced in a short time.
10 can be heated and melted. Also, if a fin 53 having an upper angle of about 5 to 30 degrees is formed between the bottom of the inner tank 52 and the outer tank 51, bubbles in that part also rise and disappear quickly. As shown in FIG. 4, the supply of the ink 10 may be performed in a stick form, a pellet form, a granular form, or the like through the supply hole 59, and the handling is simple unlike a liquid. The supply hole is normally closed by a stopper 15, and the stopper 15 is provided with a packing 16 so that the stopper 15 can be sealed. The refilled ink 10 enters the inner tank 52 and is used after passing through the filter 54, so that the nozzle 42 is not clogged with dust.

Further, as the heating means 9 for the ink 10, an electric resistor posistor and, if the ink tank 5 is made of metal, a high-frequency generator or the like may be provided so as to circumscribe the ink tank 5.

The ink recovery section 6 is formed of the above-described good heat conductive material as in the cross-sectional structure shown in FIG. 6, and the ink valve 63 may be a mechanically operated valve structure, an electromagnetic valve, or simply a check valve. . The collection hole 69 is arranged inside the ink tank 5, and the ink 10 discharged from the collection hole 69 into the ink tank 5 is always provided in the filter provided in the inner tank 52.
It passes through 54.

In order to discharge and recover the ink 10 together with the ink recovery unit 6, an air valve component 7 and an ink pressurization component 8 are provided.
As shown in FIG. 1, the air valve component 7 needs a cap member 71 made of an elastic material such as rubber having excellent heat resistance, such as fluorine rubber, silicon rubber, and epichlorohydrin rubber, and the cap member 71. The cap member 71 is constituted by an actuator 72 that moves in accordance with
It is swingably attached to 73. When the air valve component 7 is closed, the cap member 71 closes the air hole 61. The pressurizing component 8 is
An air tube member made of an elastic material such as the above-mentioned rubber with excellent heat resistance, which has a hole to allow air to pass through
81, a hollow rotary shaft 83 on which the air tube member 81 is swingably mounted, an actuator 72 for moving the hollow rotary shaft 83 when necessary, and a pressure fed into the ink tank 5 through the pressurizing hole 62. Air pump that produces high air
82. That is, when necessary, the air tube member 81 is in close contact with the pressurizing hole 61, and high-pressure air can be sent from the air pump 82 through the hollow rotary shaft 83 into the inner tank 52 from the recovery hole 68.

As described above, the heat insulating structure 11 may be formed by directly disposing a material having good heat resistance and poor heat conductivity on the head 4, the ink tank 5, and the like. When formed, the heat insulating structure 11 can be configured more effectively. Further, the heat insulating layer 13 may be made of a material having poor thermal conductivity made porous or made of cotton.

In addition, when the ink rushes out of the nozzle 42 at the time of discharging the ink, the splash preventing portion 43 may be provided at the home position as shown in FIG.

[Effects of the Invention] As described above, according to the inkjet recording apparatus of the present invention, the inner tank, the outer tank, and the ink recovery unit conduct heat from the heating means disposed in the outer tank to an extent that the ink can be melted. By being formed of a possible good heat conductive material, and having the ink recovery unit disposed near the outer tank,
Since the heat of the outer tank is conducted to the ink recovery unit, the recovered ink can be kept in a liquid state during the recording operation and can be fed to the inner tank. There is no problem that solidification occurs, ink cannot be collected, and ink leaks into the recording apparatus. In addition, by adopting a heat insulating structure in the head, the tank, and the ink recovery section, the ink can be slowed down at a speed at which the ink solidifies after the printing operation,
It is possible to prevent large bubbles from being taken into the ink, and it is possible to reduce problems caused by bubbles when used next time.

[Brief description of the drawings]

FIG. 1 is an external view of an ink jet recording apparatus of the present invention, FIG. 2 is an operation block diagram of the ink jet recording apparatus of the present invention, and FIG. 3 is an external view of a head unit which is an embodiment of the ink jet recording apparatus of the present invention. 4, FIG. 4 is a partial sectional perspective view of FIG. 3, FIG. 5 is a sectional view of an ink tank and a head of an embodiment of the ink jet recording apparatus of the present invention, and FIG. FIG. 7 is a cross-sectional view of an ink collecting section, FIG. 7 is a cross-sectional view of a heat insulating structure of an embodiment of the ink jet recording apparatus of the present invention, and FIG. 8 is a block diagram of another embodiment of the present invention. 4 Head 5 Ink tank 6 Ink recovery unit 7 Air valve constituent unit 8 Ink pressurizing constituent unit 9 Heating means 10 Ink 11 Heat insulation structure 12 Head unit 13 … Insulation layer 14… Bubble 15… Seal 16… Packing 41… Tongue 42… Nozzle 43… Splash prevention part 51… Outer tank 52… Inner tank 53… Fin 54… Filter 55 … Communication hole 56… Supply path 57… Ink supply chamber 58… Upward ceiling 61… Ventilation hole 62… Pressure hole 63… Ink valve 64… Ink receiver 65 …… Air flow path 66… Ink collection passage 67 Ink pool 68 Collection hole 71 Cap member 72 Actuator 73 Rotating shaft 81 Air tube member 82 Air pump 83 Hollow rotating shaft

Claims (1)

(57) [Claims] 1. A hot-melt type ink-jet recording apparatus using a solid ink by heating and melting at room temperature, comprising: an ink-jet head provided with a heating means for melting the ink; and supplying the ink in communication with the head. An outer tank in which a heating means for melting the ink is disposed; an inner tank which is in contact with the outer tank and supplies ink to the outer tank via a filter; and which is disposed near the outer tank and discharged from the head. And an ink recovery unit that recovers the supplied ink and feeds the ink to the inner tank. The outer tank, the inner tank, and the ink recovery unit can melt the heat from the heating unit disposed in the outer tank. And a heat insulating structure formed around the outer tank, the head, and the ink recovery unit. Door recording device.