JPH10268648A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excellent image which is free from the occurrence of fogging and which has a sufficient image density, by applying a releasing agent to the surface of an image carrier where an electrostatic latent image is formed, with a releasing agent applying means and bringing electroviscous ink held by an ink carrier into contact with the surface. SOLUTION: The releasing agent 32 is applied to the surface of the image carrier 1 where the electrostatic latent image is formed with the releasing agent applying means 3 at a specified thickness, and then, the electroviscous ink held on the surface of the ink carrier 41 at an ink developing means 4 is brought into contact with the surface of the image carrier 1 coated with the releasing agent 32 and is imparted to the part of the electrostatic latent image. An electric field acts between the ink carrier 41 and the part where the electrostatic latent image is formed, and the viscosity of the electroviscous ink 42 is increased, so that the electroviscous ink 42 is sufficiently stuck to the surface of the image carrier 1. On the other hand, the electroviscous ink 42 is not supplied to the surface of the image carrier 1 by the action of the releasing agent 32 at the part where the electrostatic latent image is not formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus which forms an electrostatic latent image on an image carrier and develops the latent image to form an image on a recording medium. The present invention relates to an image forming apparatus that forms an ink image by supplying ink to an electrostatic latent image formed on a carrier and transfers the ink image onto a recording medium to form an image.

[0002]

2. Description of the Related Art Conventionally, as typified by an electrophotographic copying machine, an electrostatic latent image is formed on the surface of an image carrier, and after developing the electrostatic latent image, the electrostatic latent image is formed on a recording medium such as paper. 2. Description of the Related Art An image forming apparatus that transfers an image onto a recording medium and forms an image on a recording medium is used.

As one of such electrophotographic image forming apparatuses, colored resin particles (toner particles) are used to develop an electrostatic latent image as disclosed in Japanese Patent Application Laid-Open No. 7-271107. One using a liquid developer dispersed in a carrier liquid is known.

Here, the liquid developer used in the electrophotographic apparatus is generally one in which charged toner particles are dispersed in an insulating carrier liquid, and the toner particles become liquid developer as an image is formed. When this liquid developer is used, it is necessary to control the concentration of the toner particles in the carrier liquid, and the management is troublesome, and most of the carrier liquid is used. Since the liquid developer is used repeatedly, there is a problem that the liquid developer is easily deteriorated.

Further, in an electrophotographic apparatus using such a liquid developer, when an image is formed on a recording medium such as copy paper, a fixing device for fixing a toner image transferred onto the recording medium or the like is used. Is required, and there is a problem that the apparatus becomes complicated and large.

[0006] Conventionally, Japanese Patent Publication No. 52-45
As shown in Japanese Patent No. 494, an ink is supplied to an electrostatic latent image formed on an image carrier to form an ink image, and the ink image is transferred onto a recording medium, and an image is formed on the recording medium. What has been proposed to be formed has been proposed.

Here, when an ink image is formed by supplying ink to the electrostatic latent image formed on the image carrier as described above, the ink is applied to a portion of the image carrier where the electrostatic latent image is not formed. Is supplied, the formed image is fogged, the ink is not sufficiently supplied to the portion where the electrostatic latent image is formed, the density of the formed image is reduced, and white spots are generated. There was a problem.

In recent years, Japanese Patent Laid-Open No.
No. 880, an electro-rheological ink is used as an ink to form an electrostatic latent image on this image carrier,
An electroviscous ink is supplied to the electrostatic latent image portion to form an ink image, and this ink image is transferred onto a recording medium to form an image on the recording medium.

Here, even when the electrorheological ink is supplied to the electrostatic latent image portion to form an ink image, the ink is still applied to the portion where the electrostatic latent image is not formed. There is a problem such as fogging of the supplied image formed.

[0010]

According to the present invention, an ink image is formed by supplying ink to an electrostatic latent image formed on an image carrier, and the ink image is formed on a recording medium such as paper or an OHP sheet. It is an object of the present invention to solve the above-described problem when an image is formed on a recording medium by transferring the image.

That is, in the present invention, when ink is supplied to an electrostatic latent image formed on an image carrier to form an ink image, ink is also supplied to a portion where the electrostatic latent image is not formed. As a result, the image formed on the recording medium is not fogged, and the ink on the portion where the electrostatic latent image is formed is not sufficiently supplied. It is an object of the present invention to stably form a good image having a sufficient image density on a recording medium without causing a drop or a white spot.

[0012]

In the image forming apparatus according to the present invention, in order to solve the above-mentioned problems, a latent image forming means for forming an electrostatic latent image on the surface of an image carrier, A release material applying means for applying a release material to the surface of the image carrier on which the latent image is formed, and bringing the electrorheological ink held on the surface of the ink carrier into contact with the surface of the image carrier on which the release material is applied And an ink developing means for forming an ink image corresponding to the electrostatic latent image, and a transfer means for transferring the ink image formed on the surface of the image carrier to a recording medium.

Here, as in the image forming apparatus of the present invention, a release material is applied to the surface of the image carrier on which the electrostatic latent image is formed by a release material applying means, and the release material is applied in this manner. When the electro-rheological ink held on the surface of the ink carrier is brought into contact with the surface of the image carrier, an electric field acts between the electro-rheological ink and the ink carrier at the portion where the electrostatic latent image is formed, so that the electro-rheological ink is applied. And the viscosity of the electrorheological ink is sufficiently adhered to the surface of the image carrier. On the other hand, in the portion where the electrostatic latent image is not formed, no electric field acts between the ink and the ink carrier, so that the electrorheological ink contacts the surface of the image carrier with the viscosity kept low, and The electrorheological ink is not supplied to the surface of the image carrier due to the action of the release material applied to the surface of the body, and the viscosity increases only in the portion where the electrostatic latent image is formed as described above. The ink is supplied to form an ink image.

When an ink image is transferred by bringing a recording medium such as paper or an OHP sheet into contact with the surface of the image carrier on which the ink image has been formed, an electrostatic latent image is formed as described above. The electro-rheological ink having increased viscosity supplied to the portion where the ink has been transferred is successfully transferred onto the recording medium, and no fogging occurs and a good image having a sufficient image density can be obtained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming apparatus according to the present invention will be specifically described below with reference to the accompanying drawings.

In the image forming apparatus according to this embodiment, as shown in FIG. 1, an image carrier 1 is used in which a dielectric layer 1b is formed on the surface of a cylindrical conductive member 1a. As a latent image forming means 2 for forming an electrostatic latent image on the surface of the image carrier 1, a discharge electrode 2 formed in a multi-stylus is used, and discharge is performed from the discharge electrode 2 to form the image carrier 1. An electrostatic latent image was formed on the surface.

Here, the image carrier 1 may be any as long as a dielectric layer 1b is formed on a conductive member 1a, and the shape thereof is not particularly limited. Instead, for example, the shape may be a drum shape or a film shape.

The material constituting the conductive member 1a of the image carrier 1 is, for example, aluminum,
Iron, copper, nickel, SUS, gold, silver, chromium, platinum,
In addition to metals such as tin and titanium and alloy materials thereof, a material in which these conductive materials are dispersed in a resin or the like can be used. When the conductive material is dispersed in the resin as described above, the resin may be polyethylene, polypropylene, polyvinyl alcohol, polyvinyl acetate,
Use ethylene-vinyl acetate copolymer, polymethyl methacrylate, polycarbonate, polystyrene, acrylonitrile-methyl acrylate copolymer, acrylonitrile-butadiene-styrene copolymer, polyterephthalate ethylene, polyurethane elastomer, polyamide, polyimide, etc. be able to.

On the other hand, examples of the material constituting the dielectric layer 1b provided on the conductive member 1a include polyester, polypropylene, polyvinyl alcohol, polyvinyl acetate, ethylene-vinyl acetate copolymer, and polymethacrylic acid. Methyl, polycarbonate, polystyrene, acrylonitrile-methyl acrylate copolymer, acrylonitrile-butadiene-styrene copolymer, polyterephthalate ethylene, polyurethane elastomer, viscose rayon, cellulose nitrate, cellulose acetate, cellulose triacetate, cellulose propionate, Cellulose acetate butyrate, regenerated cellulose, ethyl cellulose, polyamide (nylon 6, nylon 66, nylon 11, nylon 12, nylon 46, etc.), polyimide, polysulfone,
Polyether sulfone, polyvinyl chloride, vinyl chloride
Vinyl acetate copolymer, polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer, vinyl nitrile rubber alloy,
Inorganic materials such as resins such as polytetrafluoroethylene, polychlorofluoroethylene, polyvinyl fluoride, and polyvinylidene fluoride, and ceramics such as Al ₂ O ₃ , SiO ₂ and TiO ₂ can be used. May be used in combination of two or more.

Further, the latent image forming means 2 for forming an electrostatic latent image on the surface of the image carrier 1 may be one which can form an electrostatic latent image by selectively charging the surface of the image carrier 1. If not limited to the above, various means can be used.
For example, a latent image forming means of an ion flow type in which a photosensitive member is exposed by an exposure means and discharge is performed from the photosensitive member may be used.

Here, when an electrostatic latent image is formed on the image carrier 1 by the latent image forming means 2, if the surface potential of the electrostatic latent image is low, the electrorheological ink 42 used in the present invention is used. May not be sufficiently supplied onto the image carrier 1 and an image having a sufficient image density may not be obtained. Conversely, if the surface potential of the electrostatic latent image becomes too high, white Since there is a possibility that omission etc. may occur,
The surface potential at the portion of the electrostatic latent image is 200 to 2 in absolute value.
It is preferably in the range of 000V.

In this embodiment, a release material 32 is applied to the surface of the image carrier 1 on which the electrostatic latent image is formed by the release material applying means 3 with a predetermined thickness.
Thereafter, the electrorheological ink 42 held on the surface of the ink carrier 41 in the ink developing means 4 is brought into contact with the surface of the image carrier 1 on which the release material 32 is applied, and the image carrier 1
The electrorheological ink 42 is applied to the portion of the electrostatic latent image formed on the surface of the ink.

Here, the release material 32 is applied to the surface of the image carrier 1 on which the electrostatic latent image is formed as described above from the release material applying means 3.
When applying the ink, if the amount of the release material 32 applied on the surface of the image carrier 1 is small, the electrorheological ink 42 held on the surface of the ink carrier 41 is brought into contact with the surface of the image carrier 1. In addition, while the electrorheological ink 42 is also applied to the portion where the electrostatic latent image is not formed, fogging is likely to occur in an image formed, while if the coating amount of the release material 32 is too large, The electrorheological ink 42 may not be supplied properly to the portion where the latent image is formed, and the density of the formed image may be reduced and an appropriate image may not be obtained. Therefore, when applying the release material 32 to the surface of the image carrier 1, it is preferable that the thickness of the release material 32 on the surface of the image carrier 1 be in the range of 0.1 to 10 μm.

Further, a known material can be used as the release material 32. In this embodiment, the silicone oil 32 is used as the release material 32 from the viewpoint of easy handling.

In applying the silicone oil 32 to the surface of the image carrier 1 by the release material applying means 3, a part of the oil applying roller 31 is immersed in the silicone oil 32, and the oil applying roller 31 is rotated. At the same time, the amount of the silicone oil 32 on the surface of the oil application roller 31 is regulated by an oil regulating blade 33, and the oil application roller 31 moves the surface of the image carrier 1 on which the electrostatic latent image is formed. The silicone oil 32 was applied with an appropriate thickness.

On the other hand, as described above, the silicone oil 32
The electrorheological ink 42 used to form an ink image on a portion where an electrostatic latent image is formed by contacting the surface of the image carrier 1 coated with Any known material can be used, for example, an insulating liquid such as silicone oil,
A pigment to which a coloring agent such as carbon black or a color pigment or dye is added is used.

In this embodiment, the above-mentioned electrorheological ink 42 is supplied to the surface of the ink carrier 41, and the surface of the ink carrier 41 is controlled by any conventionally known means using a regulating blade or the like. The thickness of the electrorheological ink 42 was adjusted.

Here, regarding the thickness of the electrorheological ink 42 on the surface of the ink carrier 41, the supply of the electrorheological ink 42 to the portion of the image carrier 1 where no electrostatic latent image is formed is suppressed. In addition, in order to supply a sufficient amount of the electro-rheological ink 42 to the portion where the electrostatic latent image is formed, the thickness of the electro-rheological ink 42 on the surface of the ink carrier 41 is set in the range of 1 to 50 μm. It is preferable that the adjustment be made.

The electro-rheological ink 42 held on the ink carrier 41 as described above is
When an electrostatic latent image is formed on the surface of the image carrier 1 when an electrostatic latent image is formed on the surface of the image carrier 1 on which The viscosity of the ink 42 is increased, and the electrorheological ink 42 having the increased viscosity is sufficiently adhered to the surface of the image carrier 1, while the electrorheological ink is formed in a portion where the electrostatic latent image is not formed. The ink 42 remains in a low-viscosity state, and the electro-rheological ink 42 is not supplied to this portion by the action of the silicone oil 32 which is the release material 32 applied to the surface of the image carrier 1. Electro-rheological ink 4 having increased viscosity only in the portion where the electro-latent image is formed
2 was applied to form an ink image.

Here, when the electrorheological ink 42 is supplied from the ink carrier 41 to the image carrier 1 to form an ink image corresponding to the electrostatic latent image, the ink carrier 41 is If the ink carrier 41 is strongly pressed against the image carrier 1, fogging is likely to occur in the formed image, so that the ink carrier 41 is brought into contact with the image carrier 1 without applying strong pressure. Is preferred.

Next, the ink image formed on the surface of the image carrier 1 as described above is transferred by the transfer means 6 to the recording medium 7.
When the transfer paper 7 is transferred onto the transfer paper 7, the transfer paper 7 stored in the paper feed tray 71 is fed by the paper feed roller 72, and the transfer paper 7 is transferred to the image carrier on which the ink image is formed as described above. The ink image formed on the surface of the image carrier 1 was transferred by pressure onto the transfer paper 7 by the guide between the transfer roller 1 and the transfer roller 6 as the transfer means 6.

The transfer paper 7 on which the ink image has been transferred is conveyed by a conveyance belt 73 and discharged to a discharge tray 74, while the electrorheological ink remaining on the surface of the image carrier 1 after the transfer is transferred. The surface 42 of the image carrier 1 was removed from the surface of the image carrier 1 by the cleaning device 5, then the surface of the image carrier 1 was neutralized by the charge eliminating roller 8, and the above operation was repeated.

By doing so, it was possible to form a good image having sufficient image density on the transfer paper 7 without fogging or the like.

(Examples and Comparative Examples) In the examples and comparative examples, a 20 μm dielectric layer 1b made of a polyamide resin is formed on the surface of a conductive member 1a made of an aluminum drum as the image carrier 1. On the other hand, a discharge is performed using a multi-stylus discharge electrode using a 50 μm copper wire as the discharge electrode 2 to form an electrostatic latent image having a surface potential of about −600 V on the surface of the image carrier 1. Formed.

In the embodiment, a silicone oil 32 having a viscosity of about 100 cp is applied to the surface of the image carrier 1 on which the electrostatic latent image is formed by the oil application roller 31 to a thickness of about 1 μm. On the other hand, in the comparative example, the silicone oil 32 was not applied to the surface of the image carrier 1 on which the electrostatic latent image was formed.

In this embodiment and the comparative example, the electrorheological ink 42 is held on the surface of the ink carrier 41 so as to have a thickness of about 10 μm. When the body 41 is brought into contact with the surface of the image carrier 1 to form an ink image on the surface of the image carrier 1, the system speed is changed to form an ink image on the surface of the image carrier 1. The ink image was transferred onto the transfer paper 7 by the transfer roller 6 as described above, and an image was formed on the transfer paper 7.

Then, for each of the images formed in this way, the image densities in the image part and the non-image part are measured using a reflection densitometer (Sakura Densitometer PDA65), and the image part is changed according to a change in system speed. The change in image density between the image and the non-image area was obtained, and the result is shown in FIG. In FIG. 2, the solid line shows the result of the example in which the silicone oil 32 was applied to the surface of the image carrier 1 on which the electrostatic latent image was formed, and the result of the comparative example in which the silicone oil 32 was not applied in FIG. The change in density in the image portion is indicated by a bold line, and the change in density in the non-image portion is indicated by a thin line.

As a result, the electrorheological ink 42 held on the ink carrier 41 is transferred to the image carrier 1 on which an electrostatic latent image is formed.
In the embodiment in which the silicone oil 32 is applied to the surface of the image carrier 1 upon contact with the surface of
When the system speed was in the range of 10 to 30 cm / s, the image density difference between the image area and the non-image area was large, and a good image without fog was obtained.
In the case of Comparative Example in which No. 2 was not applied, there was little portion where the image density difference between the image portion and the non-image portion was large and it was difficult to obtain a good image without fogging at any system speed. there were.

[0039]

As described in detail above, in the image forming apparatus according to the present invention, the release material is applied to the surface of the image carrier on which the electrostatic latent image has been formed by the release material applying means. Since the electrorheological ink held on the surface of the ink carrier was brought into contact with the surface of the image carrier on which the mold material was applied, in the portion where the electrostatic latent image was formed,
The viscous electrorheological ink is sufficiently adhered to the surface of the image carrier, while in the portion where the electrostatic latent image is not formed, the electrorheological ink is kept at a low viscosity by the action of the release material. The viscous ink is not supplied to the surface of the image carrier, and the electrorheological ink having a higher viscosity is supplied only to the portion where the electrostatic latent image is formed, so that an ink image is formed.

When an ink image is transferred by bringing a recording medium such as paper or an OHP sheet into contact with the surface of the image carrier on which the ink image is formed as described above, the ink is supplied to a portion where the electrostatic latent image is formed. The increased viscosity of the electrorheological ink was successfully transferred to the recording medium.

As a result, when the image forming apparatus of the present invention was used, no fogging occurred and a good image having a sufficient image density could be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a diagram showing a state in which the electrorheological ink held on the ink carrier is brought into contact with the surface of the image carrier on which the electrostatic latent image is formed, as in the image forming apparatus according to the present invention; FIG. 7 is a diagram illustrating a change in image density in an image portion and a non-image portion due to a change in system speed in an example in which a mold material is applied and a comparative example in which a mold release material is not applied.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 image carrier 2 latent image forming means (discharge electrode) 4 ink developing means 41 ink carrier 42 electrorheological ink 6 transfer means (transfer roller) 7 recording medium (transfer paper)

Claims (1)

[Claims] 1. A latent image forming means for forming an electrostatic latent image on a surface of an image carrier, a release material applying means for applying a release material to a surface of the image carrier on which the electrostatic latent image is formed, and an ink. An ink developing means for contacting the electrorheological ink held on the surface of the carrier with the surface of the image carrier coated with the release material to form an ink image corresponding to the electrostatic latent image; An image forming apparatus comprising: a transfer unit configured to transfer the formed ink image to a recording medium.