JPH0839813A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To set image forming speed regardless of an ink supply time by providing a drive means driving a plurality of ink heads and circulating the respective ink heads between an ink flying position and an ink supply position. CONSTITUTION:One rod-shaped rear electrode 6 composed of aluminum and arranged in opposed relation to all of electric field forming electrodes 1a is arranged to the position opposed to a slide electrode element l through a material 10 to be recorded. As the material 10 to be recorded, commercial copy paper is used but an OHP film can be used. An ink head 2 is rotationally driven by a drive means to stepwise feed the material 10 to be recorded by a feed device while a voltage pulse is produced in a voltage source 8 and a synchronous voltage source 7 in synchronous relation to the timing bringing a charge injection electrode into contact with the electric field forming electrodes 1a to form an image. By this constitution, the next flight of ink can be performed without waiting the re-supply of ink into a slit as is conventional and an image is formed efficiently at a high speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus used in an image forming apparatus such as a printer, and more specifically, electrostatically attracts ink by an electric field according to image information to form an image on a recording medium. The present invention relates to an improvement in an ink supply system of an inkjet recording apparatus for forming a sheet.

[0002]

2. Description of the Related Art A conventional ink jet recording apparatus has an apparatus main body having a slit-shaped ink ejection portion which is arranged to face a back electrode via a recording medium, and a line in the ink ejection portion along its long side. It is composed of a plurality of control electrodes which are arranged and to which a voltage according to image information is applied, and an ink chamber which is directly connected to the ink ejecting portion and supplies ink to the ink ejecting portion. Magazine volume 118 3
Issue (1989) p. 143-149).

In one ink flight, a voltage according to image information is applied to the control electrode to generate an electric field according to the image information between the control electrode and the back electrode. The ink held in the ink ejection portion is electrostatically attracted to the back electrode side according to the strength, and the electrostatically attracted ink is attached to the recording medium.

Along with this, the ink is re-supplied from the ink chamber into the ink ejecting section, and the ink re-supplied into the ink ejecting section returns to the meniscus state suitable for image formation, and then the next ink flight occurs. Done.

[0005]

However, in the conventional ink jet recording apparatus configured as described above,
While one time of ink flight is completed in several tens of μs to several ms, there is a drawback that it takes a long time of 1 ms to several hundred ms until the inside of the ink ejection portion reaches the meniscus state suitable for image formation.

For this reason, even if the ink ejection is completed, the next ink ejection cannot be performed until the inside of the ink ejection portion reaches the meniscus state suitable for the image formation, so that there is a problem that the image forming speed is slow.

Further, in the conventional ink jet recording apparatus, since the ink is continuously supplied from the ink chamber to the ink ejecting portion, when the ink is ejected, the dielectric constant of the recording medium, the printing gap, the control voltage, etc. If the printing parameters fluctuate, the flying ink amount may become excessive, and in such a case, there is a problem that the image is crushed.

Therefore, an object of the present invention is to provide an ink jet recording apparatus which can set the image forming speed regardless of the ink supply time and has a high image forming speed.

Another object of the present invention is to provide an ink jet recording apparatus in which the amount of ink that flies at one time does not increase even if the print parameters change, and the formed image does not collapse.

[0010]

That is, the present invention has a plurality of electric field forming electrodes which are arranged to face a back electrode via a recording medium at an ink flying position and to which a voltage according to image information is applied. The sliding electrode body, an ink holding surface that holds only a certain amount of ink used for one ink flight, and one end exposed at the ink holding surface and the other end at the ink flying position where the electric field forming electrode is formed. A plurality of ink heads having a plurality of charge injection electrodes that are in contact with the ink head, an ink reservoir that supplies ink to the ink holding surface of the ink head at the ink supply position, and a plurality of the ink heads that are driven to drive the respective ink heads. The inkjet recording apparatus includes a driving unit that circulates between the ink flying position and the ink supply position.

The above-mentioned recording medium may be any one to which flying ink adheres, and is fed in a stepwise manner or continuously by a paper feeding mechanism in synchronization with image formation.

Further, the back electrode is set to a predetermined potential to form an electric field between itself and the electric field forming electrode, and if it is arranged at the same interval as all of the plurality of electric field forming electrodes. Good.

The sliding electrode body of the present invention causes the ink of the ink head set at the ink flying position between it and the back electrode to fly to the recording medium according to the image information. The plurality of electric field forming electrodes are arranged in a direction orthogonal to the direction in which the electric field forming electrodes are arranged, and the base material on which the plurality of electric field forming electrodes are stacked.

Each of the electric field forming electrodes forms an electric field corresponding to image information between itself and a back electrode when an independent voltage is applied thereto. For example, a conductive material formed in a needle shape is used. is there.

If a predetermined electric field is formed between the back electrode and the plurality of electric field forming electrodes, the ink will fly. Therefore, the back electrode may be grounded and a voltage according to the electric field may be applied to the electric field forming electrode, but a voltage that does not cause ink to fly by itself is applied to the back electrode and then applied to the electric field forming electrode. Lowering the voltage can shorten the rising time or the falling time when switching the voltage according to the image information, so that the voltage can be switched at high speed.

The ink used in the present invention may be any ink as long as it has an insulating property, and for example, general wax ink or hot melt ink can be used.

Further, the ink head conveys the ink supplied from the ink reservoir and used for one flight to the ink flying position, and is made of a heat-resistant insulating resin such as polyimide resin or polyethylene terephthalate. An insulating material such as alumina or alumina is used as a substrate, and an ink holding surface for holding a fixed amount of ink is formed on one surface of the substrate. One end of the ink holding surface is exposed at the ink holding surface and the other end is at the ink flying position. A plurality of charge injection electrodes made of a conductive material are arranged in a line so as to be in contact with.

The above-mentioned ink holding surface may be formed so as to hold only an appropriate amount of ink corresponding to one flight, and for example, a plurality of materials can be used by utilizing the difference in surface energy of the materials. The liquid repellent layer may be formed except for the periphery where the charge injection electrodes are exposed, or grooves may be formed at positions where a plurality of charge injection electrodes are exposed so as to physically hold the ink. Further, if the exposed portion or groove is divided and formed for each electric field forming electrode, the ink flying amount can be limited for each pixel, and the ink flying amount for each pixel can be more strictly limited. it can.

The charge injection electrode injects charge into the ink when the ink head is set at the ink flying position, and is in contact with the electric field forming electrode at the ink flying position. For example, it is made of a conductive material such as nickel and formed into a needle-like shape. The number of the charge injection electrodes may be equal to the pixel density, but by arranging the number equal to or higher than the pixel density, the charge is injected into the ink even if the position where the electric field forming electrode is slightly shifted at the ink flying position. can do.

The present invention has a plurality of the above ink heads. Note that the number is determined according to the image forming speed while considering the ink supply time so as not to interfere with the image forming at the ink flying position.

The driving means drives a plurality of ink heads to sequentially set the ink heads holding a fixed amount of ink on the ink holding surface to the ink flying positions, and to set the ink heads used for image formation to ink. It is only necessary to sequentially set the supply positions.

The plurality of ink heads described above may be independently formed and may be independently driven. For example, a plurality of ink heads may be arranged side by side so that the ink holding surface is on the outside. If the head body is formed and the ink head body is rotationally driven, it can be easily constructed.

[0023]

The driving means drives the ink head to set the ink head, which holds a fixed amount of ink on the ink holding surface, to the ink flying position with the charge injection electrode in contact with the electric field forming electrode. Then, when a voltage according to the image information is applied to the electric field forming electrode of the sliding electrode body, an electric field according to the image information is formed between the back electrode and the electric field forming electrode, and at the same time, the electric charge contacting the electric field forming electrode is formed. Electric charges are injected into the ink via the injection electrode. As a result, the ink injected with electric charges flies along the electric field and adheres to the recording medium, and an image corresponding to the image information is formed on the recording medium.

Then, by driving the driving means, the ink head is set to the ink supply position and ink is supplied from the ink reservoir, and the next ink head is set to the ink flying position. Therefore, simultaneously with the image formation by the next ink head, the ink can be re-supplied to the ink head previously used for the image formation.

Further, even if the strength of the electric field changes, each ink head holds only a fixed amount of ink, so that the amount of flying ink can be limited.

[0026]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

Example 1 As shown in FIG. 1, the ink jet recording apparatus according to this example has an ink reservoir 5 installed at an ink supply position.
And an ink head body 3 which is disposed above the ink reservoir 5 and is integrally formed by arranging the ink heads 2 having a width of 85 μm in a cylindrical shape so as to form the outer peripheral surface of the ink holding surface 2a. The ink electrode 2 is composed of a sliding electrode body 1 which is disposed above the inner peripheral surface of the ink head 2 and which is disposed at the ink flying position, a metaling blade 4 which is in contact with the outer peripheral surface of the ink electrode 2, and a driving means (not shown). Further, the heater 11 is arranged in the ink head 2 formed integrally.

The ink reservoir 5 is formed in a substantially box shape having an opening at the top, and hot melt ink 9 having a melting point is stored in the box in such an amount that a part of the ink carrier 3 is dipped. Then, the reservoir heater 12 was provided outside the box.

The hot melt ink 9 comprises a synthetic wax of linear polyethylene, a pigment and a dye and has a viscosity of 10 mPa · s at a melting point of 70 ° C. and 120 ° C.
s having a characteristic of surface tension of about 30 dyne / cm at 120 ° C. was used. Further, a mixture of a carnauba wax and a dye, a mixture of a synthetic wax of a linear polyethylene and a pigment, a mixture of a synthetic wax of a linear polyethylene, a mixture of a pigment and a dye, or a mixture of a fatty acid and a dye. You may use what was done. Then, by the heater 11 and the reservoir heater 12, 120 °
Warmed to C.

The ink head 2 has a size of 1 × 10 ^-6.
Holds liter of ink, width 0.1mm, depth 0.0
Ink holding surface 2 on which 5 mm ink holding groove 2b is formed
a, an ink holding groove 2b, which is arranged in a row along the bottom of the ink holding groove 2b, and a charge injection electrode having an electrode density of 300 dpi exposed on the inner peripheral surface.

Further, the sliding electrode body 1 is a machinable ceramic in which a number of electric field forming electrodes 1a formed by forming a thick film of nickel in a needle shape and having a pixel density of 300 dpi and the needle electrodes 1a are arranged side by side. The substrate 1b and the electric field forming electrode 1a are arranged so as to come into contact with the inner peripheral surface. Then, the repetition frequency is 100 Hz, the voltage is 400
A signal source 8 for generating a voltage pulse having a pulse width of v and a pulse width of 1 ms according to image information is connected.

It should be noted that the sliding electrode body 1 can be stably worn for a long period of time so that electrical contact at a portion contacting the inner peripheral surface can be obtained due to wear of itself. Alternatively, after forming the electric field forming electrode 1a on the substrate 1b made of polyimide resin or the like, the surface thereof is plated to form a convex projection, and the projection is brought into contact with the inner peripheral surface. Thus, electrical contact can be stably obtained over a long period of time.

Furthermore, the metering blade 4 is
Stainless steel is formed into a blade shape, and its tip is brought into contact with the outer peripheral surface. Other than this, a metal blade such as copper or a resin blade such as urethane may be used.

Finally, the driving means is the ink head body 2
The ink head 2 is driven to rotate in the arrow A direction by a reduction gear and a stepping motor connected to each other.

In the plurality of ink heads 2, the ink head body 3 having anisotropic conductivity is formed in consideration of the ease of manufacturing, and then a plurality of grooves are formed on the surface of the ink head body 3. Formed and configured. Specifically, the molten polyimide resin is housed in a cylindrical mold, and 2500 metal needles made of nickel are arranged in the axial direction of the cylinder at intervals of 85 μm in the circumferential direction, and electrostatic flocking is performed to mold them. After forming the ink head body having the directional conductivity, a groove having a width of 0.1 mm and a depth of 0.05 mm was formed on the outer peripheral surface of each row of metal needles by lathing and milling. A heat resistant resin such as polyethylene terephthalate may be used instead of the polyimide resin. When using these resins, ink having a melting point of 60 to 80 ° C. is used.

Then, the back electrode 6 is arranged at a position facing the sliding electrode body 1 with the recording medium 10 interposed therebetween. The distance between the ink holding surface 2a and the back electrode 7 was set to 300 μm.

The back electrode 6 is made of aluminum and has the shape of a rod arranged so as to face all the electric field forming electrodes 1a. In addition to aluminum, a metal such as copper or nickel, a conductive ceramic such as a conductive ceramic, or a conductive resin can be used. Then, in synchronism with the output pulse of the signal source 8, a voltage of −2000 V having a polarity opposite to that of the pulse and a repetition frequency of 100
Synchronous signal source 7 that outputs a pulse of Hz and pulse width of 1 ms
Connected.

A commercially available copy paper (trade name: P paper made by Fuji Xerox) was used as the recording medium 10. An OHP film or the like can also be used.

Then, the voltage source 8 and the synchronous voltage source 7 are synchronized with the timing at which the charge injection electrode contacts the electric field forming electrode 1a by rotating the ink head 2 by the driving means.
While a voltage pulse is being generated on the recording medium 10, the recording medium 10 is step-fed in the direction of arrow B by a feeding device (not shown) to form an image. When the formed image is examined, it is found that ink is missing or the image is crushed. A good image could be obtained.

Embodiment 2 As shown in FIG. 2, it is the same as Embodiment 1 except that the structure of each ink head 2 and the metering blade 4 are not provided.

As shown in FIG. 3, the ink head 2 is exposed on the ink holding surface 2a and the inner peripheral surface, and the charge injection electrodes 2e are arranged in a row at an electrode density of 300 dpi.
And an ink holding surface 2a formed by applying a fluororesin 2d while leaving a portion having a diameter of 60 μm centered on each charge injection electrode 2e.

Actually, in consideration of the ease of manufacturing, the anisotropic conductive ink head body 3 was formed, and then the liquid repellent layer was formed to form the ink head 2. More specifically, cylindrical aluminum is anodized to form porous alumina, and molten aluminum is pressed into the holes to form a composite anisotropically conductive ink head body 3, and then the outer peripheral surface thereof is formed. Then, a liquid repellent layer 2d made of fluororesin was formed on the above pattern. As another method for forming the ink head body 3, there is a method in which a sliced alumina green sheet and a sliced aluminum paste are stacked and then fired. Also,
The liquid repellent layer 2d is a coating type fluororesin (trade name: Asahi Glass CYTOP,
3M Fluorad) is applied, dried or baked, and then lapped with about 4000 wrapping paper to scrape off the fluororesin on the photosensitive resin, and further the photosensitive resin is removed with a solvent to form a lift-off state. did. Further, the liquid repellent layer 2d is formed by applying a coating type fluororesin and then etching it, or by forming PTFE or PFA.
It may be formed by electrostatic coating or dispersion coating of powdered fluororesin such as.

Then, the back electrode 6 was disposed at a position facing the sliding electrode body 1 with the recording medium 10 interposed therebetween, image formation was carried out, and the formed image was examined. A good image could be obtained without being crushed.

When the hot melt ink is not used, the heater 11 and the reserve heater 12 are not provided as shown in FIG.

Example 3 As shown in FIG. 5, the same as Example 2 except that the constitution of each ink head 2 and the ink head body were formed in the shape of an endless belt and were driven by a driving means composed of a driving roll 13. .

The ink head 2 is arranged in a row with a substrate formed of photosensitive polyimide in a belt shape, and the electrode density of 300 dp exposed on the ink holding groove 2b and the inner peripheral surface.
i charge injection electrode.

In practice, in consideration of easiness in manufacturing, the photosensitive polyimide is formed in an endless belt shape, through holes are formed in a large number of rows in the photosensitive polyimide, and the endless belt-shaped ink is plated with nickel. After forming the head body 3, the liquid repellent layer 2d having a desired pattern was formed on the outer peripheral surface.

Further, edge guides (not shown) are brought into contact with both side surfaces of the belt to prevent meandering due to its rotational drive.

Then, the back electrode 6 is arranged at a position facing the sliding electrode body 1 with the recording medium 10 interposed therebetween, an image is formed, and the formed image is examined. A good image could be obtained without being crushed. Further, since the charge injection electrodes are arranged at a higher density than the electric field forming electrode 1a, even if the belt is slightly meandered, electrical contact between them can be made and stable ink flight can be obtained. did it.

[0050]

In the ink jet recording apparatus of the present invention, the next ink head is driven immediately after the ink is ejected from one ink head set at the ink ejection position between the back electrode and the electric field forming electrode. Since the ink jetting position is set by the means, the next ink can be jetted without waiting for the ink to be resupplied into the slit as in the conventional case, and the image formation can be efficiently performed at high speed. You can

Further, since each ink head holds only a fixed amount of ink, it is possible to limit the amount of flying ink and maintain image quality even if the strength of the electric field changes due to disturbance.

[Brief description of drawings]

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

FIG. 2 is a configuration diagram of an inkjet recording apparatus according to a second embodiment of the present invention.

FIG. 3 is an enlarged view of a main part of the ink jet recording apparatus according to FIG.

FIG. 4 is a modification of the ink jet recording apparatus according to the second embodiment of the invention.

FIG. 5 is a configuration diagram of an ink jet recording apparatus according to a third embodiment of the invention.

[Explanation of symbols]

1: Sliding electrode body, 1a: Electric field forming electrode, 2: Ink head, 2a: Ink holding surface, 2e: Charge injection electrode, 5: Ink reservoir, 13: Driving means, 6: Back electrode, 10:
Recorded material.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location B41J 3/04 103 S (72) Inventor Shigenori Ando 2274 Hongo, Ebina City, Kanagawa Prefecture, inside Fuji Xerox Co., Ltd. (72) Inventor Tetsuro Kodera 2274 Hongo, Ebina City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. (72) Inventor, Koji Adachi 2274 Hongo, Ebina City, Kanagawa Prefecture, Fuji Xerox Co., Ltd. Fuji Xerox Co., Ltd., 2274 Hongo, Ebina, Japan (72) Inventor Kazuo Maruyama 2274 Hongo, Ebina, Ebina, Kanagawa, Fuji Xerox Co., Ltd.

Claims (1)

[Claims] 1. A sliding electrode body having a plurality of electric field forming electrodes which are arranged to face a back electrode via a recording medium at an ink flying position and to which a voltage according to image information is applied.
An ink holding surface that holds only a fixed amount of ink used for one ink flight, and a plurality of one ends that are exposed to the ink holding surface and that the other end abuts the electric field forming electrode at the ink flying position. A plurality of ink heads having charge injection electrodes, an ink reservoir for supplying ink to the ink holding surface of the ink head at the ink supply position,
An ink jet recording apparatus comprising: a driving unit that drives the plurality of ink heads and circulates each ink head between the ink flying position and the ink supply position.