JP2958394B2 - Ink jet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an ink jet recording apparatus which forms an image by fusing a heat-meltable ink and flying it onto a recording medium such as paper.

[0002]

2. Description of the Related Art Conventionally, as one of the ink jet recording methods, a signal carrying information to be recorded on a recording medium (hereinafter referred to as an "image signal") is produced by heating and melting a heat-fusible ink filled in a recording head. In this case, the molten ink is caused to fly toward the recording medium in response to the ink jet image to form an ink image on the recording medium.

For example, Japanese Patent Application Laid-Open No. 56-113462 discloses a technique in which ink melted by heat is atomized and ejected by a vibrator or the force of an electrostatic field or a magnetic field. Japanese Patent Application Laid-Open No. 60-90775 discloses a technique in which molten ink flowing out of a heating container is electrostatically flies toward a plurality of counter electrodes.

According to the ink jet recording system using such a hot-melt ink, a problem that occurs when using an ink that is liquid at normal temperature, specifically, feathering of the ink on a recording medium made of plain paper. (Bleeding) problems,
It is possible to effectively avoid the problem of printing operation failure due to drying of ink in the print head, clogging of nozzles, and the like.

However, in order to use these hot-melt inks, it is necessary to provide a heater inside the head, and the heater is used by the heater during the operation of the recording apparatus or until the recording apparatus becomes operable. It is necessary to heat the supply means for supplying the molten ink to the recording head, and the storage means for storing the molten ink. As described above, an ink jet recording apparatus using a heat-meltable ink requires a large amount of heat energy when the ink consumption is large, and therefore, the apparatus becomes large, the power consumption becomes large, and the power input is further increased. It takes a very long time to warm up before it can be used,
Heat dissipation during use will also increase.

Therefore, in an ink jet recording apparatus using a hot-melt ink, there has been proposed a means for automatically supplying only a required constant amount to a heating unit without heating all the inks at once. For example, Japanese Patent Publication 3-56
Japanese Patent Application Publication No. 668 discloses a method in which particulate ink is fluidized by vibrating means, and the particulate ink is dropped into a heating unit from a gap of a valve which is automatically adjusted. Japanese Patent Publication No. 3-71988 discloses a method of supplying particulate ink to a heating unit by a rotating screw. Japanese Patent Laid-Open No. 2-9637 discloses a method in which a small amount of solid ink is dropped and used near a nozzle.
No. 1993.

[0007]

However, in these systems, a supply means for supplying the molten ink liquefied by heating to the recording head is required, and the supply means must be heated. However, there is a problem that the power consumed for this purpose is much larger than the power required to melt the amount of ink actually moved to the recording medium.

In each of the above-described systems, the ink storage unit for storing the particulate ink or the solid ink is provided with an ink heating means, Since it is located above the recording head, heat radiation from the heater is easily transmitted to the ink storage unit by air convection or the like. For this reason,
If the ink is used for a long time, the temperature of the ink storage unit tends to reach the vicinity of the ink melting temperature, and the stored ink may be fixed. Melting or sticking of the particulate ink or the solid ink causes a serious obstacle such as a defective supply of the ink. For this reason, it is necessary to maintain a certain distance between the print head and the ink storage unit, or to provide a means for cooling the vicinity of the ink storage unit, which limits the miniaturization of the entire printing apparatus.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an ink jet recording apparatus which uses a heat-fusible ink and has reduced power consumption.

[0010]

According to the present invention, there is provided an ink jet recording apparatus comprising: (1) melting a powdered ink having at least a solid surface to generate a molten ink; A recording head that flies toward a recording medium in accordance with a signal carrying information to be recorded on the recording medium. (2) transports the powder ink to a predetermined powder ink flying position facing the recording head. Powder ink transport means (3) A powder ink transport means for flying the powder ink transported by the powder ink transport means to the powder ink flying position toward the recording head is provided.

Here, in the ink jet recording apparatus of the present invention, the recording head of (1) is located above the powder ink flying position, and the powder ink flying means of (3) is used for discharging the powder ink. The powder ink transported to the position
It is preferable to fly upward. In the above-mentioned ink jet recording apparatus, the above (3)
It is also a preferred embodiment that the powder ink flying means of the present invention electrostatically flies the powder ink conveyed to the powder ink flying position toward the recording head.

Alternatively, the powder ink flying means of the above (3) is to mechanically vibrate the powder ink conveyed to the powder ink flying position to fly the ink toward the recording head. There may be. In the ink jet recording apparatus of the present invention, the powder ink transporting means of (2) electrostatically or magnetically adsorbs the powder ink on the surface and moves or rotates the powder ink so that the powder ink is powdered. The powder ink transporting means may be one that transports the ink to the body ink flying position, or the powder ink transporting means (2) may be a fixedly provided powder ink carrier that carries the powder ink; And a traveling wave generating means for generating a traveling wave for moving the powder ink carried by the body ink carrier toward the powder ink flying position. Here, the traveling wave generating means may generate, for example, at least one traveling wave of a traveling wave vibration, a traveling wave magnetic field, and a traveling wave electric field.

In the above-described ink jet recording apparatus of the present invention, the recording head of (1) may be one that causes the molten ink to fly toward the recording medium by an applied electric field, or The recording head of the above (1) may fly the molten ink toward the recording medium by mechanically extruding the molten ink toward the recording medium.

The recording head of the above (1) has a plurality of molten ink passage holes arranged between a first opening facing the powder ink flying position and a second opening facing the recording medium. Even if it is provided with a base, a heater for heating and melting the powder ink flying to the first opening, and a molten ink flying means for flying the molten ink from the second opening toward the recording medium. Good. In this case, the first opening is preferably a tapered opening that gradually widens toward the powder ink flying position, and the first opening of the plurality of ink passage holes arranged in the base body. It is also a preferable embodiment that a groove connecting the openings is formed.

The powder ink used in the ink jet recording apparatus of the present invention may be a solid powder ink, or may be a capsule powder ink in which a liquid is enclosed. . When the ink jet recording apparatus of the present invention electrostatically flies powder ink, the powder ink preferably has a resistivity of 10 ⁹ Ω · m or more. Further, the powder ink used in the inkjet recording apparatus of the present invention,
It is preferable that the average particle diameter is 5 μm or more and 30 μm or less.

[0016]

In the ink jet recording apparatus of the present invention, the powder ink conveyed to a predetermined flying position is made to fly to the recording head as powder, so that only the powder ink flying to the recording head, ie, the recording ink, is recorded. It is only necessary to melt only the portion flying toward the medium for recording, and the power consumption is greatly reduced.

Further, in the present invention, when the recording head is located above the powder ink flying position and is configured to fly the powder ink upward, the recording head melts the powder ink. Since the generated heat is mainly convected upward, it is difficult for the heat to be transmitted to the ink transporting means located below, so that it is difficult for the powder ink to fuse or to be transported poorly. Contribute.

The operation of various aspects of the present invention will be described in the following embodiments.

[0019]

Embodiments of the present invention will be described below. FIG. 1 is a schematic configuration diagram of a first embodiment of the ink jet recording apparatus of the present invention. Hereinafter, each component will be outlined with reference to FIG. 1, and then further specific embodiments of the present invention will be described with reference to other drawings. (Powder ink) The powder ink has a necessary property of exhibiting heat melting property, that is, at room temperature, at least the surface is a solid having an appropriate hardness, resistance to rubbing and bending on a recording medium, Melting at a predetermined melting point, having a resistivity of 10 ⁹ Ωm or more at room temperature,
^It may be appropriately selected in consideration of having a resistivity of about ³ to 10 ⁹ Ωm. The melting temperature of the ink is desirably 70 ° C. or higher in consideration of the ink storability at room temperature, rub resistance, and the like. Further, as for the melting temperature of the ink, the lower the power consumption of the heater for heating the ink is, the more economical it is.

As a specific material of the powder ink, for example, a material in which a wax that melts at 200 ° C. or less as a main component and to which a coloring agent such as a dye or a pigment is added can be used. As the wax, a low molecular weight polyethylene wax (molecular weight of 5,000 or less) or a low molecular weight synthetic polyethylene wax (molecular weight of 10,000 or less) can be used.

The particle size of the powder ink can be used as long as it is a particle size of a developer used in a developing device or the like in an electrophotographic image forming apparatus, that is, an average particle size of 5 to 30 μm. That is, in the present invention, the wax toner used in electrophotography can be used as it is. Further, the surface of the powder ink particles has a diameter of 15 to 300 nm.
About 20 to 80% of titanium, alumina, silica, barium titanate, or the like may be attached to the surface of the powder ink particles so as to cover the powder ink particles, thereby controlling the fluidity and chargeability of the powder. Further, a magnetic powder ink in which a magnetic powder is dispersed in a powder ink can be used.

The resistivity of the powder ink containing wax as a main component was measured using a super insulation resistance meter manufactured by Yokogawa Hewlett-Packard Company. Although the Mitsui High Wax 110P used in the test showed a resistivity of 10 ¹² Ωm or more at room temperature, the resistivity gradually decreased as the ink filled between the test electrode plates was heated, and the melting point was 105 ° C.
At 10 ° C., it was 10 ⁷ Ωm. By adding a surfactant in an amount of 1 to 4% by weight to the wax, the resistivity at the melting point can be adjusted to a value in the range of 10 ⁷ to 10 ⁵ Ωm.

As another constitution of the powder ink, a heat-fusible material is used as an outer shell, and a liquid is sealed inside.
A powder ink similar to the heat fixing capsule toner used in electrophotography can also be used. In this case, it is also possible to enclose the colored ink inside, disperse a surfactant, carbon particles, and the like, melt the outer shell and mix it with the inner ink, and reduce the resistivity. . (Method for Producing Powder Ink) As a method for producing a powder ink, a method generally known as a method for producing a toner for electrophotography can be employed as it is.

Specifically, the above-mentioned materials are first stirred in a blender and kneaded in a kneader at a temperature about 10 ° C. higher than the melting temperature of the main material. After cooling the kneaded material, it is roughly pulverized by a cutter mill, and then pulverized to a desired particle size by a fine pulverizer using an air flow. Further, a powder ink of 5 to 30 μm is manufactured using an air classifier. (Powder Ink Conveying Means) The powder ink conveying means will be described with reference to FIG.

The powder ink conveying means shown in FIG. 1 comprises a powder ink storage means 1 capable of storing powder ink 3 therein, and a powder ink carrier 2 having a cylindrical or endless belt shape. The powder ink carrier 2 is made of resin, metal, ceramics, natural rubber, or a composite material thereof. The surface of the powder ink carrier 2 is coated with the powdered solid ink 3 from the powder ink storage means 1 and formed into a thin layer with a constant thickness by the regulating member 11. The thinned powder ink 3 is triboelectrically charged at the time when the ink is regulated to a thin layer, or charge is injected from the regulating member 11, or after the thinning, the charge is charged by a charger such as a corona charger. Imparted and have a uniform positive or negative charge.

The powder ink carrier 2 rotates in the direction of the arrow A shown in the figure while holding the thin layered powder ink 3 on its surface, whereby the powder ink 3 held on its surface is rotated.
Is the powder ink flying position 12 facing the recording head 10
, And return to the portion facing the powder ink storage means 1. When the powder ink is configured to return to the original position in this manner, the powder ink does not continuously stay at the powder ink flying position of the powder ink transport means, so that heat of the recording head is reduced by the powder ink. And the trouble caused by the fusion of the ink does not occur. Alternatively, the powder ink carrier 2 is fixedly held, and the powder ink 3 is transported by a traveling wave vibration by an internal vibrator, a traveling wave magnetic field, a traveling wave electric field by a linear motor or the like, and the recording ink is transferred to the recording head. The ink may be conveyed to the powder ink flying position facing 10. When a traveling wave magnetic field is used, it is necessary to disperse the magnetic powder in the powder ink.

The recording head 10 and the powder ink carrier 2
Are held out of contact with each other. (Recording Head) The recording head 10 is located near the powder ink conveying means, and the side of the recording head 10 that does not face the powder ink carrier 2 is a recording medium 60 that is relatively movable with respect to the recording head 10. And is facing. As described above, the recording head 10 and the powder ink carrier 2 are held in non-contact with each other, but the distance between the surface of the recording head 10 and the surface of the powder ink carrier 2 is Since it is necessary that the powder ink carrier 2 does not contact the meniscus of the molten ink 4 held at 10, even if the meniscus height of the molten ink 4 becomes about 100 μm, the powder ink carrier 2 does not contact the meniscus.
must be more than m apart. Also, in order for the powder ink 3 carried on the powder ink carrier 2 to fly to the recording head 10 by the electric field without causing the powder ink 3 to scatter or generate spark discharge, it is necessary that The distance may be 5 mm or less, but is preferably between 500 μm and 2.0 mm in order to stably supply the powder ink 3 to the recording head 10. Further, from the viewpoint of the operation of the present invention, it is desirable that the recording head 10 is located above the powder ink carrier 2.

In a portion of the recording head 10 facing the powdered ink carrier 2, a molten ink passage hole 8 formed in a slit 9 or a substrate 9 at a pitch corresponding to the pixel density is arranged. The molten ink passage hole 8 penetrates to the surface of the recording head 10 that does not face the powder ink carrier 2. The molten ink passage holes 8 may be arranged in a single line, a plurality of lines, or may be arranged obliquely in a zigzag pattern for each block. The diameter of the molten ink passage holes 8 may be 30 to 300 μm, but when the molten ink passage holes 8 having a diameter of 70% or more of the pixel pitch are arranged, the pixels may be arranged diagonally in a staggered manner. It is desirable to prevent mutual interference between them. (Powder Ink Flying Means) The powder ink flying means may be any means that can fly the powder ink from the powder ink conveying means to the recording head in a non-contact manner. As the method, a method of electrostatically flying charged powder ink by an electric field, a method of generating and supplying powder ink mist by mechanical vibration, and the like can be used.

As an example, a charged powder ink is applied to an electric field.
Therefore, a method of electrostatically flying will be described. Record
Powder ink carrier of molten ink passage hole 8 of head 10
The common electrode 7 is arranged around the opening 8a on the side facing
And the common electrode 7 records from the powder ink carrier 2.
Supply for supplying powder ink 3 toward head 10
An electric field is applied between the power supply 20 and the powder ink carrier 2.
It can be applied. This electric field is
The powdered ink 3 is loaded with the powdered ink according to the charging polarity of 3.
Applied to the polarity to move from the body 2 to the recording head 10
You. This electric field may be a DC electric field or an AC electric field.
The strength of the electric field to be applied is as follows.
Electric field required to separate from E.2 (in this embodiment,
0.5 × 10 ⁶ V / m or more) and Paschen
Or less than the spark discharge limit. Using an alternating electric field
If the electric field peaks at the limit of the Paschen spark discharge
Must be: When using an alternating electric field,
Direction of pulling powder ink particles back to powder ink carrier 2
Although an electric field having a polarity acting on the electrode may be applied periodically,
In this case, the powder ink particles are caused to fly to the recording head 10 side.
It is necessary to superimpose a DC electric field of a certain polarity.

Further, the electric field applied by the supply power supply 20 may be continuously applied during recording according to the ink consumption, and the supply amount of the powder ink 3 may be adjusted by the voltage. As another means, the electric field applied by the supply power supply 20 is intermittently applied according to the ink consumption, and the
May be adjusted by the application time. Further, the electric field may be applied intermittently in synchronization with the timing of the recording signal applied to the recording electrode 55 by the signal power supply 21 described in the embodiment shown in FIG. As another method, a method of controlling the peripheral speed of the powder ink carrier 2 and adjusting the amount of the powder ink conveyed to the powder ink flying position 12 facing the recording head 10 is adopted. Can also. The ink consumption is determined by the recording head 10
May be detected based on information from a means for detecting the amount of the molten ink held in the recording electrode 55.
(See FIG. 2). The detection may be performed based on information obtained by integrating signals applied to (see FIG. 2).

Around the opening 8b of the molten ink passage hole 8 of the recording head 10 facing the recording medium 60, the head driving means 5 divides the molten ink passage hole 8 for each pixel corresponding to each pixel. Has been arranged. When a slit is used as the molten ink passage hole 8, a head driving unit 5 divided for each pixel may be provided on one side or both sides of a wall constituting the slit. It is also effective to provide a liquid repellent layer around the molten ink passage hole 8 in order to maintain the ink meniscus in the molten ink passage hole 8.

When the head driving means 5 is provided with means for flying the molten ink using an electrostatic suction method, a recording electrode 55 (see FIG. 2) provided so as to be in contact with the ink in each of the molten ink passage holes 8. ) And the recording medium 60, an electric field (usually 0.5 × 10 ⁶⁾ suitable for causing ink to fly.
(Approximately 5 × 10 ⁶ V / m). This electric field may be applied between the recording electrode 55 and the recording medium 60, or the recording electrode 55 and the back electrode 30 located on the opposite side of the recording head 10 across the recording medium 60 (FIG. 2).
). Further, the back electrode 30 located on the back of the recording medium 60 may be divided and driven for each pixel, and the recording electrode 55 may be set to a common potential.

However, the head driving means 5 is not limited to the electrostatic suction type. For example, a piezoelectric element or bubbles are generated inside the molten ink passage hole 8 so as to form the molten ink passage hole 8.
A method of generating a liquid drop by causing a change in the volume of the inside, a method of generating a standing wave on the ink liquid surface by a vibrator to cause the ink to rise and adhere to the recording medium 60, and controlling the temperature of the ink for each pixel. A method of changing the viscosity to form a droplet or a liquid column by electrostatic force or vibration, a method of selectively applying a magnetic field, and the like can be used. (Ink Heating Means) A heater 6 is disposed inside the substrate 9 near the molten ink passage hole 8 of the recording head 10 or on the surface of the substrate 9 so that the temperature around the molten ink passage hole 8 is equal to or higher than the ink melting temperature. Can be controlled.
The heater 6 takes into consideration the melting temperature of the ink (40 to 300 ° C.), the reduction in power consumption, the shortening of the warm-up time, the suppression of heat radiation from the recording head 10, and the like.
Desirably, it can be heated to about 60 ° C. Further, it is preferable that the temperature can be precisely controlled at a temperature near the ink melting point. By arranging a temperature detecting means near the molten ink passage hole 8, the temperature can be set, for example, every 0.2 ° C. by feedback control. You can also. The heater 6 may be divided for each pixel,
It may be common to a plurality of pixels, and may be in direct contact with the ink. (Recording Medium) As the recording medium 60, a metal film, a cloth, or the like can be used in addition to a kind of paper, resin, or the like used in a normal electrophotographic printing apparatus. Alternatively, a method of temporarily recording on the surface of the intermediate transfer member using an intermediate transfer member having a resin surface or a metal surface, and then transferring the image to a predetermined recording medium may be employed.

As described above, the heat-meltable powder ink 3
Is stored, transported, and supplied in a non-contact manner with the heater 6 that melts the ink and the recording head 10 containing the heater 6, so that it is less affected by the heat radiation and heat transfer of the heater 6. Since the convective heat transfer by the heated air around the recording head 10 mainly affects only the upper part of the recording head 10, especially when the powder ink conveying means is arranged below the recording head 10 as in this embodiment. In addition, the temperature of the powder ink conveying means is prevented from rising, and the dissolution of ink inside the powder ink conveying means and the powder ink storing means is also prevented. For this reason, clogging of the powder ink due to ink sticking,
Occurrence of a supply failure or the like is prevented.

The powdered ink 3 is insulative in a solid state, can hold a charged charge by applying a charge by frictional charging or the like, and forms an electrostatic image force (Coulomb force) on the surface of the powdered ink carrier 2. , And non-electrostatic forces (Van der Waals forces). The thin layer of the powder ink 3 attached to the surface of the powder ink carrier 2 from the ink storage means 1 moves to the powder ink flying position 12 facing the recording head 10 as the powder ink carrier 2 rotates. Is conveyed.

Here, an electric field formed between the powder ink carrier 2 and the common electrode 7 of the recording head 10 causes
An electrostatic force acts on the powder ink 3. When the Coulomb force due to the applied electric field exceeds the adhesion between the powdered ink 3 and the powdered ink carrier 2, the powdered ink 3 flies to the common electrode 7 of the recording head 10 and the molten ink passage hole 8 , The common electrode 7, or the surface of the ink (molten ink 4) that has flown earlier and is held as it is.

The periphery of the molten ink passage 8 of the recording head 10 is heated by the heater 6 to a temperature higher than the melting temperature of the ink. Phase changes to liquid ink quickly due to heat conduction by the When the ink is melted, the resistivity decreases, so that the electric charge of the powder ink particles is neutralized at the same time as the melting. Since the molten ink 4 is held inside the molten ink passage hole 8 by surface tension, it does not return to the powder ink carrier 2 side.

The molten ink 4 is supplied to the opening 8b on the side of the molten ink passage hole 8 facing the recording medium 60 by capillary action.
The head is driven by the head driving means 5 to fly to the recording medium 60 to form an image on the recording medium 60. Hereinafter, more specific examples of the inkjet recording apparatus of the present invention will be described.

FIG. 2 is a schematic structural view of a second embodiment of the ink jet recording apparatus of the present invention, FIG. 3 is a perspective view of the recording head of the second embodiment shown in FIG. 2, and FIG. 9 is a timing chart showing a voltage application state in the second example shown. In the present embodiment, the powder ink 3 is produced by using a linear polyethylene as a main component, and adding a color dye, an antioxidant, a viscosity modifier and the like as a colorant. As a result of suggestive thermal analysis (DSC), the melting point of this ink was 100 ° C.
From 104 ° C to 104 ° C, and the peak was 102 ° C. The surface tension during melting is 0.026 N / m
(120 ° C.). The physical properties of the ink used in this example are shown below.

Oxidized polyethylene wax 98% by weight Black dye PEW BLACK (manufactured by Mitsui Toatsu Co., Ltd.) 2% by weight In addition to polyethylene, fatty acid metal salts, carnauba wax, wood wax and the like are used in addition to polyethylene. be able to. The powder ink particles are 15 μm in diameter,
An external additive of silicon dioxide for improving the fluidity of the powder and a phthalocyanine-based charge control agent are attached to the surface. When the resistivity of this ink was measured,
The solid state at 10 ° C. showed 10 ¹⁰ Ω · m or more, and the molten state at 120 ° C. showed 10 ⁸ Ω · m.

The powder ink 3 is stored inside the powder ink storage means 1, and is in contact with the rotatably supported powder ink carrier 2 at the opening of the powder ink storage means 1. The powdered ink carrier 2 is formed by coating a phenolic resin around an aluminum cylinder having a diameter of 25 mm. The powder ink 3 adheres to the surface of the powder ink carrier 2 as the powder ink carrier 2 rotates (peripheral speed: 10 mm / s), and at the outlet of the powder ink storage means 1, the regulating member 11 causes the amount of the powder ink 0.5 mg / The thickness is regulated so as to be cm ^2, and is charged to a negative polarity by frictional charging. When the charging potential of the powder ink 3 was measured, the surface potential was -5 to -5.
-20V.

As shown in FIG. 3, the recording head 10 has a molten ink passage hole 8 having a diameter of 80 μm and a pitch of 127 μm (2 μm per inch) formed on an epoxy resin substrate 9 having a thickness of 1 mm.
And a common electrode 7 is adhered around the opening 8 a on the side facing the powder ink carrier 2, and the common electrode 7 is connected to the powder ink carrier 2 via a power supply 20. 2 is connected. Further, a recording electrode 55 is adhered to the periphery of the opening 8b of the substrate 9 on the recording medium 60 side for each of the molten ink passage holes 8, and each of the recording electrodes 55 is connected to the signal power supply 21, and is connected to the back electrode 30 (see FIG. 2). A voltage can be selectively applied between the two.

A ceramic heater 6 is buried in the substrate 9 in the vicinity of the molten ink passage hole 8 to raise the temperature inside the molten ink passage hole 8 to 120 ° C., which is higher than the ink melting temperature. It is controlled to keep. The gap between the recording head 10 and the recording medium 60 is 0.5 mm,
Simultaneously with the start of recording, 1 kV is applied as a bias to the back electrode 30 by the bias power supply 25 (see FIG. 4) to excite the meniscus of the molten ink. A signal power supply 21 is applied to the recording electrode 7 in accordance with an image signal.
A pulse voltage of 1 kV is applied at a printing frequency of 100 Hz. While this print pulse is applied (0.5
ms) is 2 kV between the back electrode 30 and the recording electrode 7.
Is applied, a string is generated from the ink meniscus excited by the bias, and an ink image is formed on the recording medium 60.

The distance between the surface of the recording head 10 and the surface of the powder ink carrier 2 is 0.7 mm, and a voltage of -1 kV is applied to the powder ink carrier 2 by the power supply 20. The powder ink 3 charged to a negative polarity is caused to fly to the recording head 10 side. The application of the electric field by the power supply 20 may be performed prior to the start of recording. In the case of this embodiment, the frequency of the image signal is 100H.
By starting the application of the electric field 10 ms earlier than z by one period, the powder ink 3 is supplied to the recording head 10 by flying before the start of recording, whereby the ink for the first dot is supplied. Cutting is prevented. When the amount of the molten ink 4 is sufficient, the supply may be started at the same time as the start of printing or when a shortage of ink during printing is detected.

When the above-described voltage was applied to supply the powder ink 3 to the recording head 10, about 80% of the powder ink 3 on the powder ink carrier 2 flew toward the recording head 10. , And was quickly melted by the heat of the recording head 10. No ink returned to the powder ink carrier 2 from the molten ink passage hole 8 side. Further, a maximum potential difference of 2 kV was generated between the recording electrode 55 and the common electrode 7 during the recording, but the flowing current was slight, did not affect the recording, and the meniscus of the molten ink was stable.

In the above configuration, the printing frequency 1
As a result of printing at 00 Hz, the powder ink 3 was supplied to the molten ink passage hole 8 without any problem, and a clear image could be formed on the recording medium 60. Next, a third embodiment in which an electric field is intermittently applied as an electric field for causing powder ink to fly using the same apparatus as that of the second embodiment will be described.
Only differences from the second embodiment will be described, and description of the same parts will be omitted.

FIG. 5 is a timing chart showing a voltage application state in the third embodiment. As shown in FIG. 5, the voltage from the power supply 20 was intermittently applied during a period in which a pulse-like voltage corresponding to the image signal was not applied, in synchronization with the cycle of the image signal. The voltage value at this time is 2.
2 kV, and the voltage application pulse width is 5 ms. In this case, the effective time of the voltage application is half that of the case where the electric field is continuously applied.
), The supply rate of the powder ink 3 when the voltage is applied is increased. When the powder ink 3 was supplied to the recording head 10 by applying this voltage, the powder ink carrier 2
About 80% of the upper powder ink 3 flew toward the recording head 10 and was quickly melted by the heat of the recording head 10. There was no ink returning to the powder ink carrier 2 from the side of the molten ink passage 8, and the image could be output well as in the second embodiment.

In this embodiment, as shown in FIG. 5, since the signal voltage and the supply voltage are not applied simultaneously, this embodiment also has the effect of reducing the maximum power consumption of the entire device. A fourth embodiment in which an alternating electric field is applied as an electric field for causing powder ink to fly using the same apparatus as that of the second and third embodiments (see FIG. 2) will be described below. Only differences from the second and third embodiments will be described,
The description of the same parts is omitted.

FIG. 6 is a timing chart showing a voltage application state in the fourth embodiment. In this embodiment,
As shown in FIG. 6, in the third embodiment (see FIG. 5),
As the voltage intermittently applied by the power supply 20, a voltage obtained by superimposing an AC voltage on a DC voltage is employed. FIG.
, The surface of the recording head 10 and the powder ink carrier 2
The distance from the surface is 0.7 mm, DC voltage 600 V and AC voltage peak-to-peak 2.0 kV at a frequency of 2 kHz.
Is applied between the common electrode 7 and the powder ink carrier 2 by the power supply 20. When the powdered ink 3 was supplied under these conditions, about 90% of the powdered ink 3 on the powdered ink carrier 2 flew toward the recording head 10, and the ink was supplied satisfactorily. The melted ink also smoothly flows into the melted ink passage hole 8, and has a printing frequency of 100.
The output of the Hz image was performed without any problem.

When an AC electric field is used, the powder ink carrier 2
Among the powder inks 3 that have once separated from the surface of the powder ink 3, there is a powder ink 3 that returns to the surface of the powder ink carrier 2 with the reversal of the polarity of the electric field. When the powder ink 3 collides with a thin layer of the powder ink 3 on the surface of the powder ink carrier 2,
The kinetic energy of the returned powder ink makes it easier for other powder ink in the thin layer to detach. Therefore, the ratio of the powder ink 3 remaining on the powder ink carrier 2 after the application of the electric field can be reduced as compared with the case where only the DC electric field is applied. In the present embodiment, the same powder ink particles repeatedly pass through the thin layer forming means 11 by reducing the ratio of the powder ink remaining on the powder ink carrier 2,
It also has the effect of preventing the powder ink particles from being broken or fixed by friction.

FIG. 7 shows a modification of the powder ink conveying means which can be used in the ink jet recording apparatus according to the present invention. FIG. 7 shows that the powder ink 3
When forming a thin layer of powder, the powder ink 3 is supplied from the powder ink storage means 1 to the auxiliary roll 31,
Is used to transfer the powder ink 3 on the auxiliary roll 31 to the powder ink carrier 2 using the bias. The auxiliary roll 31 is a cylinder made of conductive urethane foam,
A bias potential of -500 V is applied by the power supply 23 to cause the powder ink 3 to electrostatically adhere to the powder ink carrier 2. The auxiliary roll 31 may not be in contact with the powder ink carrier 2 or may be in contact with the powder ink carrier 2 by a minute pressure.

In the structure of this embodiment, when the powder ink carrier 2 is rotated at a peripheral speed of 10 mm / s, a thin layer of the powder ink 3 uniformly charged at a transport amount of 0.4 mg / cm ² is obtained. was gotten. The surface potential of the thin layer of the powder ink 3 is -1.
When the image was recorded at 0 V under the same conditions as in the second embodiment, the ink was supplied to the recording head 10 without any problem, and the recorded image was also good.

In this embodiment, the charging of the powder ink 3 is stabilized without being influenced by the environment, since the charging is applied by the action of the bias potential without applying mechanical friction to the powder ink 3. In addition, it has the effect of preventing breakage and sticking of ink particles due to mechanical friction. FIG. 8 is a diagram showing another embodiment of the powder ink conveying means.

In this embodiment, the thin layer of the powder ink 3 is formed by the soft elastic member 32. The soft elastic member 32 of this embodiment is made of silicone rubber, is supported on the outer wall of the powder ink storing means 1 by a stainless steel leaf spring, and has a linear pressure of 50 g / cm on the surface of the powder ink carrier 2. Is in contact with In the configuration of this embodiment, when the powder ink carrier 2 was rotated at a peripheral speed of 10 mm / s, a thin layer of the powder ink 3 uniformly charged at a transport amount of 0.4 mg / cm ² was obtained. Was. The surface potential of the thin layer of powder ink is-
It was 12V.

When an image was recorded using the powder ink conveying means of this embodiment under the same conditions as in the second embodiment,
The supply of the powder ink to the recording head 10 was performed without any problem, and the recorded image was also good. Further, even if the voltage applied to fly the powder ink 3 to the recording head 10 was reduced to 0.8 kV, there was no shortage of the supply of the powder ink, and the efficiency was higher than in the second embodiment. In this embodiment, since the soft elastic member 32 is used, when the powder ink 3 passes through the contact portion between the soft elastic member 32 and the surface of the powder ink carrier 2, each powder ink Since the surface of the soft elastic member 32 is elastically deformed according to the diameter of the particles, the chance of contact between the powder ink particles and the regulating member is increased as compared with the case where a metal member such as a stainless steel plate is used,
Further, the contact area between the powder ink particles and the deformed soft elastic member 32 also increases. Therefore, the frictional charging effect of the powder ink 3 is higher than that of the second embodiment. Further, unlike the embodiment shown in FIG. 7, the auxiliary roll 31 and the power supply 23 are not required, and a thin layer of powder ink in a good state can be formed with a simple configuration.

As the material of the soft elastic member 32, in addition to the above silicone rubber, ethylene-propylene rubber,
Examples include urethane rubber, butadiene-styrene rubber, nitrile rubber, chloroprene rubber, and fluoro rubber. FIG.
FIG. 4 is a diagram showing an embodiment for the purpose of positively injecting charges into the powder ink to reduce the ratio of the powder ink charged to a polarity opposite to a desired polarity.

In this embodiment, a thin layer is formed while a voltage of -200 V is applied by a power source 23 to a brass regulating member 33 having a thickness of 2 mm. The regulating member 33 and the powder ink carrier 2 are in contact with each other at a linear pressure of 30 g / cm.
In the configuration of the present example, when the powder ink carrier 2 was rotated at a peripheral speed of 10 mm / s, the transport amount was 0.5 mg /
A thin layer of powdered ink 3 uniformly charged in cm ² was obtained. The surface potential of the thin layer of the powder ink 3 is -12 V,
The proportion of the positively charged powder ink of the opposite polarity was also as low as 2% or less. When the powder ink 3 is supplied to the recording head 10, about 90% of the powder ink 3 on the powder ink carrier 2 flies to the recording head 10 side, and the recording head 1
It was quickly melted by the heat of 0. There was no ink returning to the powder ink carrier 2 from the side of the molten ink passage 8 and the output of an image performed under the same conditions as in the second embodiment was a good result.

In this embodiment, since the charge is directly injected from the conductor to the surface of the powder ink particles, a charge of a desired polarity can be applied to the powder ink particles in contact with the regulating member 33.
Furthermore, compared to the case of triboelectric charging, it is less susceptible to changes in the surrounding environment. Therefore, the ratio of the positively charged powder ink having the opposite polarity can be reduced. FIG. 10 is a view showing another example of the powder ink conveying means. In this example, a powder ink carrier of a type in which a belt-like member (carrier belt) 25 is stretched around two axes and each axis is driven. Is provided.

The powder ink 3 is applied to the carrier belt 25 from the ink storage means 1 and is regulated by the regulating member 11 to a constant transport amount (0.5 mg / cm ² ). afterwards,
The rotation of the drive shaft moves the carrier belt 25, and conveys the powder ink 3 to a portion facing the charging means (corona charger) 34. In this embodiment, a positive charge is applied to the thinned powder ink 3 by the corona charger 34. The shaft 35 on the side facing the recording head 10 is made of aluminum so that an electric field can be applied between the common electrode 7 (see FIG. 2) of the recording head 10 by the power supply 20. After supplying the powder ink 3 to the recording head 10, the carrier belt 25 moves to the opening of the powder ink storage unit 1, and the powder ink 3 is newly applied to the carrier belt 25.

Using the powder ink conveying means of the present embodiment, recording was performed under the same conditions as in the second embodiment. Carrier belt 25
The distance between the surface of the recording head and the recording head 10 was 0.7 mm, and only the direction of the electric field applied between the aluminum shaft 35 and the common electrode 7 of the recording head by the power supply 20 was reversed from that in the second embodiment. About 90% of the powder ink on the powder (2 kV) and the powder ink carrier 2 flew to the recording head 10 side, and the image output was also a good result.

Even if the polarity of the powder ink 3 is made positive as in the present embodiment, the polarity of the electric field applied by the power supply 20 is inverted to transfer the powder ink 3 to the recording head 10.
Can fly without any problem. Further, by using the corona charger 34, +1 is added to the powder ink 3.
A uniform charge of 5 V can be given.
Even if the applied voltage by 0 was reduced to 0.8 kV, it was possible to supply the powder ink efficiently. Further, as another effect of the present embodiment, by transferring the powder ink using the belt, the degree of freedom that the position of the powder ink storage means 1 can be set to an arbitrary position is obtained. At this time, the length of the carrier belt, the number of drive shafts, and the like may be arbitrary.

As another configuration of the recording head 10 that can be used in the present invention, FIGS. 11 and 12 show a type having a groove for holding molten ink. FIG. 11 is a cross-sectional view of the recording head, and FIG.
It is the top view seen from. A molten ink passage hole 8 perforated according to image density and a recording electrode 55 provided around the substrate 9 are formed on a substrate 9, and a groove 18 is formed on a surface opposite to the recording electrode 55 to form a molten ink holding portion. And Groove 1
Reference numeral 8 extends in the arrangement direction of the molten ink passage holes 8. Groove 1
Numeral 8 has a trapezoidal cross section with a wide opening side, and the width of the opening is 160 μm, which is wider than the diameter of the molten ink passage hole 80 of 80 μm, to increase the retention of the molten ink.

When an image was output using the recording head of the present embodiment under the same conditions as in the second embodiment, the supply of ink was performed without any problem, and a good image could be output on the recording medium. Was. The feature of this embodiment is that the molten ink 4
Is formed so as to extend over the plurality of molten ink passage holes 8, so that the ink can be stably supplied even if the amount of ink consumption varies for each molten ink passage hole. If the molten ink holding groove 18 is filled with ink, each of the molten ink passage holes is always filled with a common amount of ink by capillary action, so that the powdered ink is arranged in the direction in which the molten ink passage holes are arranged. May be supplied uniformly. Even if there is a difference in the amount of ink consumed for each pixel, there is no shortage of ink in a specific molten ink passage hole, and stable image output is possible.

FIG. 13 is a plan view showing another modification of the recording head. In order to arrange the molten ink passage holes 8 having a diameter of 80 μm at a pitch of 84 μm (300 per 1 inch), eight of them are arranged in one. This is an example in which blocks are arranged diagonally one by one. The recording electrode 55 is provided around the molten ink passage hole 8 as in the embodiment shown in FIGS.
Each of them is pulled out to the end of the substrate 9 and a signal power supply 21
(See FIG. 2). The common electrode 7 is provided for each block on the surface of the substrate 9 opposite to the recording electrode 55. Similarly to the embodiment shown in FIGS. 11 and 12, a common ink holding groove 18 (see FIG. 11) is provided for each block, and the flying powder ink is melted and held in the holding groove 18. be able to. The common electrode 7 of each block is connected to a power supply 20 via a connection line 13.
(See FIG. 2).

By arranging the molten ink passage holes 8 of the recording head as in this embodiment, the present invention can be applied even to a pixel density that, when arranged in a line, interferes with the adjacent molten ink passage holes 8. Can be applied. In the present embodiment, the positions of the molten ink passage holes 8 are differently arranged in the moving direction of the powder ink carrier 2 in each block, but if the maximum amount is 1 mm or less, the powder ink The difference in the distance between the carrier and the recording head is small, and the influence on the flying of the powder ink is small. Even if the powder ink flies only in a part of the ink holding groove due to its different position, the holding groove 1
8 is common in the block, and the molten ink forms a meniscus over one holding groove by surface tension. For this reason, the molten ink immediately flows to the shortage portion, and the molten ink passage holes are filled with the molten ink without any problem.

FIG. 14 is a diagram showing an example of a recording head utilizing the change in the volume of an ink flow path for flying molten ink.
In this embodiment, a piezoelectric element 14 is provided independently on the inner wall of the molten ink passage hole 8 for each of the molten ink passage holes, and a pulse-like electric signal is applied to the piezoelectric element 14 to the signal electrode 5.
5 and the ground electrode 15. The signal electrode 55 and the ground electrode 15 are electrically insulated from each other by the insulating layer 16. A voltage pulse of 50 to 70 V is applied to the piezoelectric element 14, and the piezoelectric element 14 receives the voltage pulse and deforms in the width direction of the molten ink passage hole 8,
The volume of the molten ink passage hole 8 is changed. Due to this volume change, the molten ink causes ink droplets to fly toward the recording medium.

In the case of this embodiment, the side facing the powder ink conveying means (the side on which the common electrode 7 is disposed) has a large opening area, and therefore the molten ink in the thickness direction of the substrate 9 on that side. Exercise is small. In addition, ink holding groove 1
Since the molten ink inside 8 absorbs the pressure wave, the ink does not fly as droplets from the opening on the side facing the powder ink transporting means.

Further, in this embodiment, a heater can be used as an element for changing the volume of the molten ink passage hole 8. The thermal energy applied by the heater instantaneously raises the local ink temperature above the boiling point of the ink, and causes the ink to fly as droplets from the opening due to the volume change of the generated bubbles. FIG. 15 is a diagram showing an embodiment in which ink is supplied from the powder ink conveying means to the recording head by using vibration.

The powder ink conveying means in this embodiment comprises an endless powder ink carrier belt 25, and the powder ink carrier belt 25 has the same powder ink storage means 1 as the embodiment shown in FIG. And a regulating member 11 to form a thin layer of the powder ink 3. Inside the portion of the powder ink carrier belt 25 of the present embodiment facing the recording head 10, the ultrasonic vibration means 7 is disposed in contact with the powder ink carrier belt 25. The distance between the powder ink carrier belt 25 and the recording head 10 is 2 mm, and a partition wall 19 is provided in the space of the opposing portion so as not to be in contact with both the powder ink carrier belt 25 and the recording head 10. The inside of the partition wall 19 is separated from the surrounding space.

By generating ultrasonic vibration in the vibrating means 17, the powder ink 3 on the powder ink carrier belt 25 is scattered. A part of the scattered powder ink 3 extends along the inside of the partition wall 19 along with the ink holding groove 1 of the recording head 10.
8, and becomes the molten ink 4 by the heat of the recording head 10 and is held in the ink holding groove 18. Further, a part of the scattered powder ink 3 is applied to the powder ink carrier belt 25.
Returning upward, the powder ink carrier belt 25 returns to the inside of the powder ink storage means 1 as the belt 25 moves.

When an image was output using the powder ink conveying means of this embodiment under the same conditions as in the second embodiment, the supply of the powder ink was carried out without any problem, and a good image output on the recording medium was obtained. Was able to do. In this embodiment, since the powder ink is supplied by vibration without using an electric field, the distance accuracy between the powder ink carrier belt 25 and the recording head 10 is set more precisely than when the electric field is used. The distance does not need to be increased, and the distance can be increased to 5 mm. Further, in the present embodiment, since the powder ink 3 is supplied by mechanical vibration, it is not necessary to precisely control the amount of conveyance and the amount of charge of the powder ink 3 formed on the powder ink carrier belt 25. In this case, by adjusting the amplitude of the vibration of the vibrating means 17, the supply amount of the powder ink to the recording head 10 can be adjusted.

[0072]

As described above, according to the present invention,
In an ink jet recording apparatus using a heat-meltable ink, the amount of the molten ink can be drastically reduced as compared with the related art. Further, it becomes possible to supply the powder ink in a non-contact manner, and it becomes unnecessary to provide a tank for the molten ink, a means for transporting the molten ink, a path for transporting the molten ink and a means for heating the ink in the tank. Therefore, the power consumption can be significantly reduced, and the warm-up time for recording preparation can be shortened. In addition, troubles due to clogging of the ink supply path and entry of air bubbles do not occur.

Further, since the means for storing and transporting the solid ink can be kept out of contact with the portion having the heater, it is possible to prevent troubles such as a supply failure due to the solid ink sticking beforehand. Become.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of an ink jet recording apparatus of the present invention.

FIG. 2 is a schematic configuration diagram of a second embodiment of the ink jet recording apparatus of the present invention.

FIG. 3 is a perspective view of a portion of a recording head according to a second embodiment shown in FIG. 2;

FIG. 4 is a timing chart showing a voltage application state in the second embodiment shown in FIG. 2;

FIG. 5 is a timing chart showing a voltage application state in a third embodiment.

FIG. 6 is a timing chart showing a voltage application state in a fourth embodiment.

FIG. 7 is a view showing a modification of the powder ink conveying means.

FIG. 8 is a diagram showing another embodiment of the powder ink conveying means.

FIG. 9 is a diagram illustrating an example in which charges are positively injected into powder ink.

FIG. 10 is a diagram showing another example of the powder ink conveying means.

FIG. 11 is a sectional view of a recording head.

FIG. 12 is a plan view of a recording head.

FIG. 13 is a plan view showing another modification of the recording head.

FIG. 14 is a diagram illustrating an example of a recording head that uses a change in volume of an ink flow path for flying molten ink.

FIG. 15 is a diagram showing an embodiment in which powder ink is supplied from the powder ink conveying means to the recording head by using vibration.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 powder ink storage means 2 powder ink carrier 3 powder ink 4 molten ink 5 head driving means 6 heater 7 common electrode 8 molten ink passage hole 10 recording head 11 regulating member 12 powder ink flying position 30 back electrode 55 recording Electrode 60 Recording medium

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-256877 (JP, A) JP-A-1-241452 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41J 2/015 B41J 2/01

Claims (8)

(57) [Claims] 1. A method for producing a molten ink by fusing powder ink having at least a solid surface, and directing the molten ink toward a recording medium in response to a signal carrying information to be recorded on the recording medium. A recording head that causes the powder ink to fly, a powder ink transport unit that transports the powder ink to a predetermined powder ink flying position below the recording head and that faces the recording head, An ink jet recording apparatus comprising: powder ink flying means for flying the powder ink conveyed to the powder ink flying position upward toward the recording head. 2. A method for producing a molten ink by fusing powder ink having a solid surface at least, and directing the molten ink toward a recording medium in response to a signal carrying information to be recorded on the recording medium. A recording head that causes the powder ink to fly, a powder ink transport unit that transports the powder ink to a predetermined powder ink flying position facing the recording head, and a powder ink transport unit that moves the powder ink to the powder ink flying position. An ink jet recording apparatus comprising: powder ink flying means for electrostatically flying the conveyed powder ink toward the recording head by an AC electric field. 3. A method for producing a molten ink by fusing powder ink having at least a solid surface, and directing the molten ink toward a recording medium in response to a signal carrying information to be recorded on the recording medium. A recording head that causes the powder ink to fly, a powder ink transport unit that transports the powder ink to a predetermined powder ink flying position facing the recording head, and a powder ink transport unit that moves the powder ink to the powder ink flying position. An ink jet recording apparatus, comprising: a powder ink flying means for mechanically vibrating the conveyed powder ink to fly the powder ink toward the recording head. 4. A method for producing a molten ink by fusing powder ink having at least a solid surface, and directing the molten ink toward a recording medium in response to a signal carrying information to be recorded on the recording medium. A recording head that causes the powder ink to fly, a powder ink transport unit that transports the powder ink to a predetermined powder ink flying position facing the recording head, and a powder ink transport unit that moves the powder ink to the powder ink flying position. Powder ink flying means for flying the conveyed powder ink toward the recording head, wherein the powder ink conveying means carries the powder ink, and is fixedly provided powder ink. It has a carrier and traveling wave generating means for producing a traveling wave for moving the powder ink carried on the powder ink carrier toward the powder ink flying position. Inkjet recording device. 5. The traveling wave generating means generates at least one traveling wave of a traveling wave vibration, a traveling wave magnetic field, and a traveling wave electric field.
The inkjet recording apparatus according to any one of the preceding claims. 6. A molten ink is generated by melting powder ink having at least a solid surface, and the molten ink is directed to a recording medium in response to a signal carrying information to be recorded on the recording medium. a recording head for flying Xiang Te, the powder ink, a powder ink transfer means for transferring a predetermined powder ink flying position opposed to the recording head, the powder ink ejecting position by the powder ink transfer means Powder ink flying means for flying the powder ink conveyed to the recording head toward the recording head , wherein the recording head faces the powder ink flying position
Along with the powder ink flying position
Tapered first opening, and a first opening facing the recording medium.
A plurality of molten ink passage holes connecting the two openings are arranged.
And the powder that has flown into the first opening
A heater for heating and melting the body ink;
The solution that is made to fly from the second opening side toward the recording medium
An ink jet recording apparatus comprising: a molten ink flying means . 7. A plurality of said melts arranged on said substrate.
A groove in the ink passage hole that connects the first openings is formed.
Ink <br/> jet recording apparatus according to claim 6, characterized by being formed. 8. A capsule-like powder having a liquid enclosed therein.
Melting the body ink to produce a molten ink;
The melted ink toward the recording medium, to record on the recording medium body
Recording head that flies in response to a signal carrying information to be printed
When a predetermined flour the powder ink, opposed to said recording head
A powder ink transfer means for transferring to the body ink ejecting position, the powder ink ejecting position by the powder ink transfer means
The powder ink conveyed to the recording head
Louis inkjet recording apparatus to <br/> characterized in that a powder ink flying means for flying.