JPH11153907A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stick ink only to an electrostatic latent image part and to obtain an excellent image having a sufficient image density without a void and fog, in the case that an electrostatic latent image is formed and the ink comes into contact with the surface of an image carrier wich is coated with a nonconductive liquid so as to form an ink image. SOLUTION: In this device, the ink 41 is supplied from an ink developing device 40 to the surface of the image carrier 10 on which the electrostatic latent image is formed by a latent image forming device 20 and which is coated with a nonconductive releasing agent 31 by a releasing agent coating device 30, to form the ink image corresponding to the electrostatic latent image. In such a case, it is constituted so that the time TNIP from the contact of the ink with the surface of the image carrier to the separation of the ink, the time TK needed to stick the ink to the electrostatic latent image part formed on the surface of the image carrier through the releasing agent and the time TW needed to stick the ink to a part except the electrostatic latent image part through the releasing agent satisfy the condition of TW>TNIP>TK.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming an electrostatic latent image on the surface of an image carrier and applying a non-conductive release material to the surface of the image carrier. The present invention relates to an image forming apparatus configured to contact an ink with a surface of an image carrier formed and coated with a release material to form an ink image corresponding to an electrostatic latent image on the surface of the image carrier. Are adequately adhered only to the portion of the image carrier on which the electrostatic latent image is formed, have a sufficient image density, and are characterized in that an image without omission or fog can be obtained. .

[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
No. 494, etc., an electrostatic latent image is formed on the surface of an image carrier, and a non-conductive liquid is applied to the surface of the image carrier, thus forming an electrostatic latent image. The ink is brought into contact with the surface of the image carrier on which the non-conductive liquid is applied, and the ink is adhered to a portion of the electrostatic latent image formed on the surface of the image carrier to form an electrostatic latent image. There has been proposed an image forming apparatus in which an ink image corresponding to the image formation is formed on the surface of an image carrier, and the ink image is transferred from the surface of the image carrier to a recording medium to form an image.

However, in such an image forming apparatus, the ink does not sufficiently adhere to the portion of the electrostatic latent image formed on the surface of the image carrier, and the density of the formed image is reduced. Problems such as omission of an image to be formed, and conversely, fogging of an image to be formed due to adhesion of ink to a portion of the image carrier where an electrostatic latent image is not formed. was there.

[0008]

According to the present invention, an electrostatic latent image is formed on the surface of an image bearing member, and a non-conductive release material is applied to the surface of the image bearing member. In the image forming apparatus described above, an image is formed and the ink is brought into contact with the surface of the image carrier on which the release material is applied, so that an ink image corresponding to the electrostatic latent image is formed on the surface of the image carrier. It is an object to solve such a problem as described above.

That is, in the image forming apparatus of the present invention, an ink is brought into contact with the surface of an image carrier on which an electrostatic latent image is formed and a non-conductive liquid is applied, and the surface of the image carrier is contacted with ink. In forming an ink image, the ink is properly applied to the portion of the electrostatic latent image formed on the surface of the image carrier, while the ink is suppressed from adhering to the portion where the electrostatic latent image is not formed. It is an object of the present invention to stably obtain a good image having sufficient image density and no omission or fogging.

[0010]

In order to solve the above-mentioned problems, an image forming apparatus according to the present invention has a latent image forming apparatus for forming an electrostatic latent image on a surface of an image carrier, and an image carrier. A release material coating device for applying a non-conductive release material to the surface of the body, and an electrostatic latent image is formed, and ink is brought into contact with the surface of the image carrier on which the release material is applied to form an electrostatic latent image. In an image forming apparatus including an ink developing device that forms a corresponding ink image, a time T _NIP until the ink comes into contact with and separates from the surface of the image carrier is referred to as T _NIP . The time required to adhere to the portion of the electrostatic latent image formed on the surface of the image carrier through the release material is T _K , and the ink in contact with the surface of the image carrier has an electrostatic latent image formed through the release material. If you have a T _W the time required to adhere to the no part In this case, the condition of T _W > T _NIP > T _K was satisfied.

Here, in the image forming apparatus according to the present invention, the time T _NIP until the ink contacts and separates from the surface of the image carrier is a distance from the time when the ink contacts and separates from the surface of the image carrier. It is the value obtained by dividing the nip width by the system speed, which is the moving speed of the image carrier, and the time required for the ink in contact with the surface of the image carrier to adhere to the portion where the electrostatic latent image is formed through the release material. T _K is a value obtained by dividing the film thickness of the non-conductive release material applied to the surface of the image carrier by the moving speed at which the ink moves through the release material at the portion where the electrostatic latent image is formed. The time T _W required for the ink in contact with the surface of the image carrier to adhere to the portion where the electrostatic latent image is not formed through the release material is the non-conductive release time applied to the surface of the image carrier. The thickness of the mold material
In a portion where the electrostatic latent image is not formed, the value is a value obtained by dividing by a moving speed at which the ink moves through the release material.

Then, as described above, T _w > T _NIP > T _K
In order to satisfy the above condition, the nip width until the above-mentioned ink comes into contact with and separates from the image carrier or the moving speed of the image carrier is changed to adjust the value of T _NIP described above. The value of T _K or _Tw is adjusted by changing the type or thickness of the non-conductive release material applied to the surface of the image carrier, the thickness thereof, the type of ink, and the like.

[0013] In this way, the above-mentioned T _w> T _NIP> T _K
When the condition is satisfied, when an electrostatic latent image is formed and the ink is brought into contact with the surface of the image carrier on which the release material is applied to form an ink image on the surface of the image carrier,
While this ink is appropriately adhered to the portion of the electrostatic latent image formed on the surface of the image carrier, the ink is suppressed from adhering to the portion where the electrostatic latent image is not formed, and sufficient image density is obtained. , And a good image without omission or fogging can be stably obtained. Furthermore, from the viewpoint of preventing fog and ensuring image density more stably, preferably 0.9 T _W ≧ T _NIP ≧ 1.1 T _K , more preferably 0.8 T _W ≧ T _NIP ≧ 1.2 T _K. To satisfy the conditions of

Here, as the image bearing member, a photosensitive member having a dielectric layer formed on the surface of a conductive member or an electrophotographic photosensitive member having a photosensitive layer formed on the surface of a conductive member is used. be able to.

In this image carrier, the conductive member may be made of, for example, a metal such as aluminum, iron, copper, nickel, SUS, gold, silver, chromium, platinum, tin, or titanium. In addition to these alloy materials, a material in which these conductive materials are dispersed in a resin 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, ethylene-vinyl acetate copolymer, polymethyl methacrylate, polycarbonate, polystyrene, acrylonitrile. -Methyl acrylate copolymer, acrylonitrile-butadiene-styrene copolymer, poly (ethylene terephthalate), polyurethane elastomer, polyamide,
Polyimide or the like can be used.

Further, as a material constituting the dielectric layer provided on the conductive member, for example, polyester,
Polypropylene, polyvinyl alcohol, polyvinyl acetate, ethylene-vinyl acetate copolymer, polymethyl methacrylate, polycarbonate, polystyrene, acrylonitrile-methyl acrylate copolymer, acrylonitrile-butadiene-styrene copolymer, poly (ethylene terephthalate), polyurethane Elastomer, viscose rayon, cellulose nitrate, cellulose acetate, cellulose triacetate, cellulose propionate, cellulose acetate butyrate, ethyl cellulose regenerated 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, Alkenyl nitrile rubber alloy, polytetrafluoroethylene, polychlorofluoroethylene, polyvinyl fluoride, and resins such as polyvinylidene fluoride, Al
₂ O _3, SiO _2, a ceramic such as TiO ₂ may be an inorganic material, it is also possible to use a combination of such a dielectric material of two or more.

As the photosensitive layer provided on the above-mentioned conductive member, a photosensitive layer generally used in an electrophotographic photosensitive member can be used.

In a latent image forming apparatus for forming an electrostatic latent image on the surface of an image carrier, an image carrier having a dielectric layer formed on the surface of a conductive member is used. Use a discharge device or an ion-flow type electrostatic head to form an electrostatic latent image by applying a charge according to the image to the dielectric layer on the surface of the body, and form a photosensitive layer on the surface of the conductive member. In the case of using an image carrier made of a photosensitive member, various types of exposure devices such as a charging device for charging the surface of the image carrier and a laser device for exposing the surface of the image carrier thus charged are used. To be used in combination.

[0019]

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

In the image forming apparatus of this embodiment, as shown in FIG. 1, an image carrier 10 having a conductive member 11 on the surface of which a dielectric layer 12 is formed is used.

Then, the image carrier 10 is rotated at an appropriate system speed, and an electrostatic latent image is formed on the surface of the image carrier 10 by a latent image forming device 20.

Here, as the latent image forming apparatus 20 described above,
In this embodiment, an ion flow type electrostatic head 20 is used, and the surface of the image carrier 10 is selectively charged by the electrostatic head 20 to form an electrostatic latent image.

Next, a non-conductive release material 31 is applied from the release material application device 30 to the surface of the image carrier 10 on which the electrostatic latent image is formed as described above.

Here, when the non-conductive release material 31 is applied to the surface of the image carrier 10 by the release material application device 30, in this embodiment, silicone oil or the like is used as the release material 31, and this release material is used. A part of the application roller 33 is immersed in the storage container 32 in which the mold material 31 is stored, and the coating roller 33 is rotated to hold the release material 31 in the storage container 32 on the outer peripheral surface of the coating roller 33. The amount of the release material 31 held as
4, the release material 31 having a predetermined thickness is guided to the image carrier 10 by the application roller 33.
Is applied to the surface of the image carrier 10 so as to have an appropriate film thickness.

Then, the ink 41 is supplied from the ink developing device 40 to the image carrier 10 on which the release material 31 is applied, and the portion of the electrostatic latent image formed on the surface of the image carrier 10 is To form an ink image on the surface of the image carrier 10.

When an ink image is formed on the surface of the image carrier 10 by the ink developing device 40 in this manner, the ink 41 accommodated in the main body 42 of the device is replaced with the ink carrier 43 in the form of a drum. And the amount of the ink 41 held on the surface of the ink carrier 43 is regulated by the regulating member 44 so that the ink 41 held on the surface of the ink carrier 43 has a predetermined thickness. To Then, the ink 41 held on the surface of the ink carrier 43 is brought into contact with the surface of the image carrier 10,
The ink 41 is applied to a portion of the electrostatic latent image formed on the surface of the image carrier 10.

Here, in the image forming apparatus of this embodiment, the system speed of the image carrier 10 which rotates as described above, the type and thickness of the release material 31 applied to the surface of the image carrier 10 and its use By appropriately controlling the type of the ink 41, the nip width until the ink 41 comes into contact with and separates from the surface of the image carrier 10, the time T until the ink 41 comes into contact with and separates from the surface of the image carrier 10 _NIP , the time T _K required for the ink 41 in contact with the surface of the image carrier 10 to adhere to the portion of the electrostatic latent image formed on the surface of the image carrier 10 through the release material 31, and the surface of the image carrier 10 The time T _W required for the ink 41 in contact with the ink to adhere to the portion where the electrostatic latent image is not formed through the release material 31 is T _W.
> T _NIP > T _K.

In this way, when the ink 41 is brought into contact with the surface of the image carrier 10 to form an ink image on the surface of the image carrier 10 as described above, the ink 41 While the ink 41 is appropriately attached to the portion of the electrostatic latent image formed on the surface of the image carrier 10, the ink 41 is prevented from attaching to the portion where the electrostatic latent image is not formed, and the electrostatic latent image is formed on the surface of the image carrier 10. Is formed.

After the ink image is formed on the surface of the image carrier 10 as described above, the ink image formed on the surface of the image carrier 10 by the transfer roller 50 as the transfer device 50 is transferred onto the recording medium 1. I am trying to transfer it.

After the ink image is transferred onto the recording medium 1 as described above, the ink 41 remaining on the surface of the image carrier 10 after the transfer is removed by the cleaning device 60 using a cleaning blade 61. After being removed from the surface of the image carrier 10, the charge remaining on the surface of the image carrier 10 is removed by the charge removing device 70, and a new electrostatic latent image is again formed on the surface of the image carrier 10 by the latent image forming device 20. Then, the above operation is repeated.

Here, in the image forming apparatus of this embodiment, the system speed of the image carrier 10 rotating as described above, the type and thickness of the release material 31 applied to the surface of the image carrier 10, The time T _NIP until the ink 41 contacts and separates from the surface of the image carrier 10 is appropriately controlled by controlling the type of the ink 41 to be performed, the distance until the ink 41 contacts and separates from the surface of the image carrier 10, and the like. , Image carrier 10
The time T _K required for the ink 41 in contact with the surface of the image carrier to adhere to the portion of the electrostatic latent image formed on the surface of the image carrier 10 through the release material 31, and the ink 41 in contact with the surface of the image carrier 10 The time T _W required to adhere to a portion other than the portion of the electrostatic latent image through the release material 31 is _{expressed as} T _W > T _NIP >
T _K is satisfied, and the ink 41 is applied to the image carrier 1
Since the toner is appropriately adhered only to the portion of the electrostatic latent image formed on the surface of No. 0, a satisfactory image having a sufficient image density and no missing or fogging can be obtained.

(Experimental Example) In this experimental example, the system speed of the rotating image carrier 10 was changed in the image forming apparatus of the above embodiment.

In this experimental example, the image carrier 1
The surface of the image carrier 10 on which the electrostatic latent image is formed to have a potential of -630 V on the surface of the image carrier 10 by the electrostatic head 20 described above. In applying the non-conductive release material 31 from the release material application device 30 to the above, a silicone oil having a viscosity of 2 cP (manufactured by Toray Dow Corning Co., Ltd .: silicone oil SH200) is used for the release material 31. 31 was applied to the surface of the image carrier 10 on which the electrostatic latent image was formed so that the film thickness became 10 μm.

When the ink 41 is supplied from the ink developing device 40 to the image carrier 10 to which the release material 31 has been applied as described above, the ink 41 is supplied.
Lithographic printing ink (Best Cure OL SD 7
No. 97 Ink 1L: T & K TOKA). 2ML
Regiuser (manufactured by T & K TOKA) and No. 2 Dilute using Contex (manufactured by T & K TOKA),
Using an ink whose viscosity was adjusted to 20000 cP, the ink 41 was coated on the surface of the ink carrier 43 with a film thickness of 10
μm, and the ink 41 is formed so that the electrostatic latent image is formed as described above and the contact pressure becomes 0.36 kg / mm on the surface of the image carrier 10 on which the release material 31 is applied. And the nip width until the ink 41 comes into contact with and separates from the surface of the image carrier 10 is 3.5.
mm.

Then, the image carrier 1 which rotates as described above
Image formation by changing the system speed of 0,
Changes in image density in an image portion where an electrostatic latent image was formed and changes in image density in a non-image portion where an electrostatic latent image was not formed were examined. The results are shown in FIG.

[0036] Consequently, in the case of slower system speed than V _W shown in FIG. 2, no ink 41 in the image portion adheres, while fog image is generated to be formed, faster system speed than V _K In the case of, ink 4
No. 1 was not sufficiently supplied, and the image density sharply decreased.

Therefore, in order to have a sufficient image density in the image portion and obtain a good image without fogging in the non-image portion, the system speed is set in the range of V _{W to} V _K. It was necessary to do.

Here, the value of V _W in FIG. 2 is about 240 mm / s and the value of V _K is about 480 mm / s, and the ink 41 contacts the surface of the image carrier 10 as described above. Since the nip width until the separation is 3.5 mm, the time T _K until ink adheres to the portion of the electrostatic latent image formed on the surface of the image carrier 10 is about 7.3 ms, The time T _W required for the ink 41 to adhere to the portion where no image is formed is about 14.6 ms. Therefore, the time T _NIP required for the ink 41 to come into contact with the surface of the image carrier 10 and separate therefrom is taken as T _NIP . When it is within the range of 7.3 ms to 14.6 ms, a satisfactory image having sufficient image density and no missing or fogging was obtained.

The image forming apparatus according to the present invention
The present invention is not limited to the image forming apparatus shown in the above-described embodiment. For example, as shown in FIG. 3, a belt-shaped ink carrier 43 in the ink developing device 40 may be used. It is also possible to extend the nip width until the ink 41 held by the ink carrier 43 comes into contact with the surface of the image carrier 10 and separates from the ink carrier 43 over the roller 45.

By using the belt-shaped ink carrier 43 and increasing the nip width until the ink 41 comes into contact with and separates from the surface of the image carrier 10, the system speed of the rotating image carrier 10 is reduced. Even if you accelerate it,
The time T _NIP until the ink 41 contacts and separates from the surface of the image carrier 10 falls within the above range, and the contact pressure at which the ink 41 contacts the surface of the image carrier 10 also decreases,
The ink image formed on the image carrier 10 is not disturbed, and a good image can be obtained at high speed.

Further, in the image forming apparatus shown in the above embodiment, the image carrier 10 in which the dielectric layer 12 is formed on the surface of the conductive member 11 is used, but as shown in FIG. Alternatively, a photoconductor in which a photosensitive layer 13 is formed on the surface of a conductive member 11 can be used as the image carrier 10.

When an electrostatic latent image is formed on the surface of the image carrier 10 made of such a photoreceptor by the latent image forming device 20, the latent image forming device 20 is used as shown in FIG. A charging device 21 for uniformly charging the surface of the carrier 10 and an exposure device 22 for performing exposure according to image information on the surface of the image carrier 10 thus charged
After the surface of the image carrier 10 is uniformly charged by the charging device 21, the surface of the image carrier 10 is exposed from the exposure device 22 in accordance with image information, and the surface of the image carrier 10 is An electrostatic latent image is formed on the surface.

Although not shown, the conductive member 11
The nip width can be increased by using the image carrier 10 having an elastic layer formed thereon, or by using the image carrier 10 using an elastic material as a dielectric material constituting the dielectric layer 12. is there. Here, as the elastic material, for example, EPDM (ethylene propylene rubber), NR (natural rubber), SBR (styrene rubber), NBR (nitrile rubber), CR (chloroprene rubber), IIR (butyl rubber), silicone rubber, fluorine Rubber and urethane rubber.

[0044]

As described above in detail, in the image forming apparatus according to the present invention, an electrostatic latent image is formed and ink is brought into contact with the surface of the image carrier on which the release material has been applied to form an electrostatic latent image. In forming an ink image corresponding to an image, a time T required for the ink to come into contact with the surface of the image carrier and to separate.
_NIP , the time T _K required for the ink in contact with the surface of the image carrier to adhere to the portion of the electrostatic latent image formed on the surface of the image carrier through the release material, and contact with the surface of the image carrier The relationship between the time T _W required for the ink to adhere to a portion other than the portion of the electrostatic latent image through the release material, T _W > T _NIP >
In order to satisfy the condition of T _K , the ink in contact with the surface of the image carrier is appropriately adhered only to the portion where the electrostatic latent image is formed.

As a result, when an image is formed by the image forming apparatus of the present invention, the ink sufficiently adheres to the surface of the image carrier on which the electrostatic latent image is formed, but the electrostatic latent image is not formed. Adhesion of the ink to the surface of the image carrier was suppressed, and a good image having sufficient image density and free from fog and fog was stably obtained.

[Brief description of the drawings]

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

FIG. 2 shows an image density in an image portion where an electrostatic latent image is formed and an image density in a non-image portion where an electrostatic latent image is not formed in an experimental example using the image forming apparatus of the embodiment. FIG. 9 is a diagram illustrating a relationship that changes with a change in system speed of the image carrier.

FIG. 3 is a schematic explanatory view of an image forming apparatus according to another embodiment using a belt-shaped ink carrier.

FIG. 4 is a schematic explanatory view of an image forming apparatus according to another embodiment using an image carrier having a photosensitive layer formed on the surface of a conductive member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Image carrier 20 Latent image forming device 30 Release material coating device 31 Release material 40 Ink developing device 41 Ink

Claims (1)

[Claims] A latent image forming apparatus for forming an electrostatic latent image on the surface of the image carrier; a release material applying apparatus for applying a non-conductive release material on the surface of the image carrier; An image developing apparatus for forming an ink image corresponding to an electrostatic latent image by bringing ink into contact with the surface of the image carrier formed and coated with a release material; T _{NIP is} the time required for the ink to contact and separate from the surface of the image carrier, and is required for the ink in contact with the surface of the image carrier to adhere to the portion of the electrostatic latent image formed on the surface of the image carrier through the release material Assuming that the time required is T _K and the time required for the ink in contact with the surface of the image carrier to adhere to the portion where the electrostatic latent image is not formed through the release material is T _W , T _W > T _NIP >
An image forming apparatus that satisfies the condition of T _K.