JPH04190278A - Image formation device - Google Patents

Abstract

PURPOSE:To maintain a high image quality even if used for a long time and repeatedly, by providing a liquid coating device which seals at least recessed portions out of minute recessed and projected portions at a surface protection layer, by means of a liquid material that prevents the adhesion and piling up of hydrophilic substance generated by ozone. CONSTITUTION:A liquid material 25 in a container 24 is drawn up due to the capillarity of a capillary tube 28, and supplied to a space between two rotating coating rollers 26, 27 and then, coated on the surface of a rotating photosensitive body 1 so that a thin and uniform coated film may be formed. Meanwhile, a lot of ozone is generated by the operation of an electrification corona electric discharger 2, and as a result, a hydrophilic compound is formed, and as the liquid material is coated on the protection layer surface of the body 1 and surface recessed portions are treated with hole sealing by means of the liquid, the adhesion and piling up of the hydrophilic substance on the protection layer surface are interrupted. As a result, the photosensitive body surface does not become hydrophilic, of an abnormal image prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus using an electrophotographic method, that is, a Carlson process.

[Conventional technology]

Currently, as a copy printing method, an electrostatic copying method using the Carlson process, a so-called electrophotographic method, is most widely used. Here, the electrophotographic method uses a photoreceptor in which a photosensitive layer made of a photoconductive material is formed on a conductive support, the photosensitive layer is charged in a dark place, and then imagewise exposed to expose only the exposed areas. The electric charge is selectively dissipated to obtain an electrostatic latent image, and this latent image is developed with electrostatic fine particles called toner, which is composed of an imaging material such as a dye or pigment and a binder such as a polymeric substance. This is an image forming method in which the resulting visible image is transferred and fixed onto a transfer material such as paper to form an image.

FIG. 4 shows an electronic copying machine which is an example of an image forming apparatus using the above electrophotographic method. A photoreceptor 1 comprising a photoreceptor layer laminated on the surface of a grounded drum-shaped conductive support is rotated clockwise in the figure, and at this time, the photoreceptor 1 is charged by a charging means comprising a charging corona discharger 2. The photosensitive layer is uniformly charged.

The corona discharger 2 has a corotron system in which a charge wire 3 made of a tungsten wire with a diameter of 40 to 100 μm is stretched, and a grid is placed near the opening of the corona discharger in order to equalize uneven discharge. There is a scorotron system in which a high voltage of, for example, 4000 to 8000 volts is applied to the charge wire 3.
The photosensitive layer is charged by corona discharge at this time.

Next, the uniformly charged photosensitive layer is imagewise exposed in the exposure section 4 to form an electrostatic latent image, and then the latent image is visualized as a toner image in the developing device 5.

The toner image is transferred to a transfer paper 7, which is an example of a transfer material, by the corona discharge action of the transfer corona discharger 6, and then this transfer paper 7 is transferred to the photoreceptor 1 by the separation corona discharger 8.
more separated. The toner image on the separated transfer paper 7 is fixed by a fixing device 9, and becomes a hard copy.

On the other hand, the toner remaining on the photoreceptor 1 after the transfer is cleaned by the cleaning device 10, and then the photosensitive layer is neutralized by the quenching device 15, thereby completing the series of copying steps.

The image forming apparatus shown in FIG. 5 uses a charging roller 102 instead of the charging corona discharger 2 shown in FIG. The photoreceptor 1 rotates while contacting the surface of the photoreceptor 1, and charges the photosensitive layer of the photoreceptor 1 to a predetermined polarity. Also, in the example of Figure 5.

A transfer roller 106 is used in place of the transfer corona discharger 6 shown in FIG. 4, and the toner image on the photoreceptor 1 is transferred onto the transfer paper 7 by the roller 106. The other configurations in FIG. 5 are the same as in FIG. 4.

Using the charging roller 102 has the advantage that the applied voltage can be lower than when using the corona discharger 2, and the concentration of ozone generated can also be lowered, but the influence of ozone on the photoreceptor, which will be described later, is There is no big difference from when corona discharger 2 is used.

The photosensitive layer of the photoreceptor 1 used in the above-described image forming apparatus includes: (1) Se or Se-containing metal (Se-As, 5e-Te, 5
A photoconductive layer mainly composed of e-As-Te, etc.).

■A photoconductive layer made of an inorganic photoconductive material such as zinc oxide or cadmium sulfate dispersed in a binder; ■A photoconductive layer made of an organic photoconductive material such as poly N-vinylcarbazole and trinitrofluorenone or an azo pigment; Photoconductive layers made of amorphous silicon-based materials are generally known.

The basic characteristics required of a photoreceptor having such a photosensitive layer are (a) the ability to charge the photosensitive layer to an appropriate potential in a dark place, and (b) the ability to dissipate the charge on the photosensitive layer in a dark place. There are few.

(c) The ability to quickly dissipate the charge on the photosensitive layer by irradiating the photosensitive layer with light.

In addition to these basic characteristics, the photoreceptors having each of the above-mentioned photosensitive layers have characteristics and drawbacks that are excellent in practical use.

For example, selenium or selenium alloys (Se-Te, 5e-As
, 5e-Te-As system, etc.) has been commonly used since the earliest times, and while it has excellent photosensitivity, it is subject to mechanical loads in the electrophotographic process, such as developing equipment. The disadvantage is that the surface is susceptible to scratches caused by external damage from the transfer paper, cleaning equipment, jammed transfer paper, etc., and this tends to affect image quality (white lines, black lines, etc.). There is.

Furthermore, in recent years, organic photoreceptors having a photosensitive layer made of the above-mentioned organic photoconductive material have been rapidly developed due to reasons such as low manufacturing cost, less environmental pollution, and relatively flexible photoreceptor design.

In general, an organic photoreceptor is a material in which a charge-generating material and a charge-transporting material are dispersed or dissolved in a binder resin and coated on a conductive support. A charge generation layer (CGL) that has the function of transport, a charge generation layer (CGL) that has the function of charge generation, a charge transport layer (CTL) that has the function of holding charged charges and transporting the charges injected from the charge generation layer, and furthermore, Accordingly, charge injection from the support is blocked. Alternatively, a functionally separated type is known, which has a structure in which layers having functions such as preventing light reflection on a support are laminated.

These organic photoreceptors have excellent characteristics as mentioned above, but because their photosensitive layer is made of organic material, their surface hardness is low, and when they are actually used in the copying process, they are easily damaged by developer, transfer paper, and cleaning. It also has an essential drawback in that it is susceptible to wear and scratches due to mechanical loads from cleaning members of the device and the like.

This abrasion of the photosensitive layer causes a decrease in the charging potential, and local scratches cause streak-like abnormal images to appear on copies, both of which are important problems that affect the life of the photoreceptor.

In order to overcome these drawbacks, a method has been proposed in which a surface protective layer is provided on the surface of the photosensitive layer to improve its durability against mechanical loads received inside and outside the copying machine. This protective layer is
It is particularly advantageous and applicable to selenium-based photoreceptors that have photosensitive layers mainly made of selenium or its alloys, which are prone to surface scratches, and organic photoreceptors whose surfaces are abrasion-resistant. It can also be applied to a photoreceptor having a photosensitive layer made of a crystalline silicon-based material. To be more specific, a method of providing an organic film on the surface of a photosensitive layer (Japanese Patent Publication No. 3
8-015446), a method of providing an inorganic oxide (Japanese Patent Publication No. 43-014517), a method of laminating an insulating layer after providing an adhesive layer (Japanese Patent Publication No. 43-027591), or plasma VCVD method/photo CVD A method of laminating an a-8i layer, a 5-8i:N:H layer, an a-5i:O:H layer, etc. by a method such as JP-A-57-179859, JP-A-59-0
No. 58437), etc. are known.

These methods have been recognized to be effective in improving the mechanical durability of the photoreceptor surface. However, when laminating organic films, it is necessary to use a solvent that does not affect the organic photoreceptor, so there is little freedom in selecting materials, and silicone-based protective layers require chemical protection from ozone, etc. However, there are many problems that still need to be solved in practical use.

Against this background, the application of carbon or highly hard thin films mainly composed of carbon as a surface protective layer of photoreceptors has become active in recent years.

For example, a protective layer made of amorphous carbon or hard carbon is provided on a photosensitive layer (Japanese Patent Laid-Open No. 60-2491155).
, one in which a diamond-like carbon protective layer is provided on the outermost surface (Japanese Patent Application Laid-Open No. 61-255352), and one in which a high hardness layer mainly composed of carbon is formed on the photosensitive layer (Japanese Patent Application Laid-open No. 61-255352).
-264355), or a protective layer made of a plasma organic polymer film containing at least nitrogen atoms, oxygen atoms, halogen atoms, alkali metal atoms, etc. on the organic photosensitive layer (JP-A-63-97961~ No. 4), a protective layer consisting of an amorphous hydrocarbon film generated by glow discharge containing at least chalcogen atoms, group II atoms, group II atoms, group II atoms, etc. is provided on the organic photosensitive layer ( JP-A-63-220166-9).

In all of these proposals, carbon or a highly hard thin film mainly composed of carbon (i-carbon film or It belongs to what is collectively called a diamond-like carbon film).

These surface protective layers can also be applied to photoreceptors having the various photosensitive layers shown in (1) to (2) above, but since such surface protective layers are obtained by a film forming process that does not use a solvent, The effect on organic photoreceptors is limited by lJX,
In addition, this surface protective layer has high hardness, and the film itself is resistant to oxidizing atmospheres such as ozone.
In particular, excellent effects can be obtained in improving the durability of selenium-based photoreceptors and organic photoreceptors.

However, when photoreceptors made of such materials are used repeatedly over a long period of time during the electrophotographic process, copies or prints may run in environments with high humidity or rapid increases in humidity, resulting in so-called "image blurring". It has become clear that there is still a problem in which abnormal images called ``are generated''.

The estimated mechanism of occurrence of image blurring is ozone generated by the corona discharge of the charging corona discharger 2 shown in FIG. 4, ozone generated during the charging operation of the charging roller 102 shown in FIG. 5, or various ions. Hydrophilic substances consisting of hydrophilic compounds containing nitrogen compounds, carboxyl groups, aldehyde groups, etc. are formed by reacting with impurities such as moisture and carbon dioxide in the air, and these substances adhere and deposit on the surface of the photoreceptor. This is thought to be due to the photoreceptor surface becoming hydrophilic. Water is adsorbed on the surface of the photoreceptor which has become hydrophilic in this manner, and the two-dimensional resistance of the surface decreases, resulting in an abnormal image.

In the case of a photoreceptor having a highly hard surface protective layer containing carbon or carbon as a main component, the surface may have fine irregularities (pitch 10).
0 to 5000 people, axial direction with a depth of about 50 to 2500 people,
This occurs when the above-mentioned hydrophilic substance adheres to and accumulates in the recesses because irregularities of random shapes with no directivity are formed in the circumferential direction.

As a method for preventing the above-mentioned image deletion, (1) a method of heating the photoreceptor (JP-A-59-208558, JP-A No. 60-0)
No. 95467, No. 61-132977, No. 62-26
2065, etc.), (2) A method of absorbing and decomposing corona products from a corona discharger by using activated return fibers, Ni, Pt, Au, beryllium alloys, etc. for grids, shield cases, or charge wires (special methods). Kaisho 50-348
No. 28, No. 63-311365, No. 64-68774
JP-A-1-210974, JP-A-1-319062, etc.), (3) Colon discharge current control method (JP-A-1-237
No. 569, etc.) are disclosed. However, although the heating method is highly effective, it is still insufficient.Although the absorption and decomposition methods are also effective, they still have problems with sustainability. Furthermore, these methods have the disadvantage that their construction is very complicated.

[Problem to be solved by the invention]

The present invention has been made based on the above-mentioned novel recognition, and its purpose is to eliminate the above-mentioned conventional drawbacks and to maintain high image quality even after repeated use over a long period of time. [Means for Solving the Problems] In order to achieve the above object, the present invention provides an image forming apparatus which includes at least a photosensitive layer on a conductive support, carbon or carbon as a main component, and A photoreceptor comprising a surface protective layer having fine irregularities on the surface laminated in this order, the photoreceptor layer of the photoreceptor being charged,
In an image forming apparatus that imagewise exposes the surface to form an electrostatic latent image and visualizes the latent image with a toner, at least the concave portions of the fine irregularities of the surface protective layer are covered with hydrophilic particles caused by ozone. An image forming apparatus is proposed that is equipped with a liquid applicator that seals pores with a liquid material that prevents adhesion and accumulation of substances.

The above-mentioned liquid materials include antioxidant solution, antioxidant-containing isoparaffinic hydrocarbon solution, antioxidant-containing aliphatic hydrocarbon solution, antioxidant-containing silicone oil, isoparaffinic hydrocarbon solution, and aliphatic hydrocarbon solution. It is advantageous to use at least one of hydrogen solutions and silicone oils.

〔Example〕

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

FIG. 1 shows an embodiment in which the present invention is applied to the conventional image forming apparatus shown in FIG. On the surface of the drum-shaped conductive support 2o, at least a photosensitive layer 21,
It is constructed by laminating in this order a surface protective layer (a-C:H film) 22 which contains carbon or carbon as a main component and has fine irregularities on the surface. As the photosensitive layer 21,
Consisting of various photoconductive layers such as selenium-based, inorganic-based, organic-based, or amorphous silicon-based materials as exemplified in (1) to (2) above,
Moreover, the surface protective layer 22 is the same as the high hardness surface protective layer mainly composed of carbon or carbon as previously explained as a conventional example.
They are laminated using various methods as in the past. For example, the surface protective layer 22 can be created using a plasma CVD apparatus that is known per se, and the surface protective layer 22 thus obtained has a Knoop hardness of 2300 k, for example.
g/llIn2 and specific resistance of 1012 Ω·■, and the film thickness can be formed to, for example, about 0.7 μm. Also, the random minute irregularities formed on its surface.

The pitch is, for example, about 0.3 μm, and the depth is, for example, 0.3 μm.
It is 2 μm.

The same equipment as the various process equipment shown in FIG. 4 is arranged around the photoreceptor 1 shown in FIG. There isn't.

Therefore, a copy image is basically formed on the transfer paper 7 in exactly the same manner as in the prior art, but since this has been explained previously, the explanation thereof will be omitted. The image forming apparatus shown in FIG. 1 is provided with a liquid coating device 23 in addition to these process devices. This device is placed between the cleaning device 10 and the charging corona discharger 2, and its structure and operation are as follows.

That is, this device 23 has a container 24, and the container 24
contains a liquid material 25, and this liquid 25 is applied to the surface protective layer 22 of the photoreceptor 1, as will be described later, to prevent hydrophilic substances generated by ozone from adhering to or depositing on the protective layer 22. perform the work of

Further, in the vicinity of the charging corona discharger 2, a plurality of (two in the illustrated example) application rollers 26 and 27 are arranged so as to be driven to rotate in the directions of the arrows. These rollers 26 and 27 are close to each other.

Alternatively, they rotate while contacting each other and are in close contact with the surface of the photoreceptor.

The liquid material 25 in the container 24 is pumped up by the capillary action of the capillary tube 28, and the liquid material 25 is drawn up by the two rotating application rollers 26, 2.
7. In this way, the liquid material 25 is
It adheres to the circumferential surfaces of the book application rollers 26 and 27, and is applied to the surface of the photoreceptor 1, which rotates clockwise, to form a thin and uniform film. At least the surfaces of the application rollers 26 and 27 are made of an elastic material so that the liquid material can be uniformly applied to the surface of the photoreceptor. Further, in the middle of the capillary tube 28, a regulator 29 consisting of, for example, a cock is provided to adjust the flow rate of the liquid material passing through the capillary tube 28, and thereby the amount of the liquid material applied to the surface of the photoreceptor can be adjusted as appropriate. .

The liquid material applied to the surface protective layer 22 of the photoreceptor 1 seals at least the concave portions of the fine irregularities on the surface of the protective layer. On the other hand, a large amount of ozone is generated by the operation of the charging corona discharger 2, which causes hydrophilic compounds (
However, since a liquid material is applied to the surface of the protective layer of the photoreceptor 1 and the recesses on the surface are sealed with this liquid, the surface of the protective layer, especially the recesses, Adhesion or deposition of hydrophilic substances is prevented. Therefore, the surface of the photoreceptor does not become hydrophilic, and therefore, even if the photoreceptor 1 is used repeatedly for a long period of time, the abnormal image (image blur) described above is prevented from occurring, and high-quality images are always maintained. Obtainable.

The liquid material 25 that prevents hydrophilic substances generated by ozone from adhering to or depositing on the surface protective layer 22 includes:
At least an antioxidant solution, an antioxidant-containing isoparaffinic hydrocarbon solution, an antioxidant-containing aliphatic hydrocarbon solution, an antioxidant-containing silicone oil, an isoparaffinic hydrocarbon solution, an aliphatic hydrocarbon solution, and a silicone oil. One is used. Also, such liquid materials.

The liquid must have a high resistance so that the surface of the photoreceptor 1 can be charged without any trouble by the charging corona discharger 2, and the liquid must have a high resistance so as not to inhibit the image exposure in the exposure section 4. The liquid must be transparent to light.

In addition, as mentioned above, the liquid material is a hydrophilic substance generated by ozone generated during the operation of the corona discharger 2, and the surface protective layer 2
It is desirable to apply the liquid material to the surface of the photoreceptor 2 before charging the photoreceptor layer 21 of the photoreceptor 1 with the charging corona discharger 2. Therefore, in the example shown in FIG.
3 is disposed between the cleaning device 10 and the charging corona discharger 2.

Also, the thickness of the liquid material coating applied to the photoreceptor surface is
Although it varies depending on the viscosity and volatility of this liquid, it is desirable that the liquid be applied to the entire surface of the surface protective layer 22 at the time of receiving corona discharge from the corona discharger 2 so as to reliably prevent the adhesion of hydrophilic substances. When a coating film is formed and the developing device 5 performs a developing operation, it is preferable that the liquid remains in the surface recesses of the surface protective layer so as not to interfere with the developing operation.

Of course, there is considerable tolerance in the amount of liquid applied, and when expressed in terms of consumption, it can be, for example, about 3 to 10 cc/10,000 cycles.

FIG. 3 shows an embodiment in which the present invention is applied to the image forming apparatus shown in FIG. The difference between this embodiment and the embodiment shown in FIG. 1 is that, as previously explained with reference to FIG. In addition to the fact that the charging roller 102 is used as a means for transferring the toner image formed on the photoreceptor onto the transfer paper 7, the charging roller 102 is used as a means for applying the liquid material. The point is that there is.

That is, an elastic coating roller 126 that is rotated in the same counterclockwise direction as the charging roller 102 while being close to or in contact with the charging roller 102 is supported in contact with the surface of the photoreceptor, and the liquid material in the container 24 is coated with the elastic coating roller 126 . 25 is supplied between these rollers 102 and 126 via a capillary tube 28 and a regulator 29, and after the liquid adheres to the circumferential surfaces of these rollers 102 and 126, it is applied to the surface of the photoreceptor. In this manner, in this embodiment, the charging roller 102 is used to apply the liquid to the surface of the photoreceptor, so the number of application rollers can be reduced and the cost thereof can be reduced. Furthermore, since the charging roller 102 is also coated with the liquid material, adhesion or deposition of hydrophilic substances on the roller 102 can be prevented. Further, in this example, at least the surface of the application roller 126 needs to be made insulating in order to prevent the electric charge of the charging roller 102 from leaking to the application roller 126 due to contact between the application roller 126 and the charging roller 102.

Other components and operations are the same as those of the embodiment shown in FIGS. 1 and 2.

Next, specific examples and comparative examples will be shown.

A copy test was conducted using the image forming apparatus shown in FIGS. 1 to 3 and using a phenolic antioxidant solution as the liquid material 25. The copy speed is 30 cpsi. Furthermore, as a comparative example, a test was also conducted in the case where the liquid coating device 23 was not provided, and the results shown in Table 1 were obtained. Evaluation is 5 pieces/m
The characteristic value was whether the resolution chart of the image was well resolved on the copy.O Very well resolvedO Well resolvedΔSlightly poor resolutionXNo resolution at all In the case of the comparative example in which no image was formed, image blurring occurred in a high temperature environment after 10,000 cycles of copying, but in the case of Example 1, no image blurring phenomenon was observed even after 50,000 cycles, and a stable image was obtained. Ta.

In addition, the liquid material of Example 1 was mixed with silicone oil containing phosphorus antioxidant (viscosity 2 cs), isoparaffin hydrocarbon (
A copy test was performed in the same manner as in Example 1 except that the replacements were with Isopar H) and silicone oil (viscosity 2cs). In both cases, no image blurring occurred even after 50,000 cycles, and good images were obtained. It was done.

The present invention can also be applied when a belt-shaped photoreceptor is used instead of a drum-shaped photoreceptor.

〔Effect of the invention〕

As described above, according to the structures described in claims 1 and 2, it is possible to prevent the surface protective layer of the photoreceptor from deteriorating, and it is possible to obtain stable, high-quality images over a long period of time.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus according to the present invention, FIG. 2 is a diagram schematically showing an enlarged cross-sectional shape of a photoreceptor, and FIG. 3 is a configuration showing another embodiment. 4 and 5 are configuration diagrams showing examples of conventional image forming apparatuses, respectively. 1... Photoreceptor 2o... Conductive support 21
...Photosensitive layer 22...Surface protective layer 23...
-Liquid coating device 25...Liquid material Fig. 1 Fig. 2 -82''.

Claims (2)

[Claims] (1) A photoreceptor comprising at least a photoreceptor layer and a surface protective layer containing carbon or carbon as a main component and having fine irregularities on the surface, laminated in this order on a conductive support, the photoreceptor In an image forming apparatus that charges the photosensitive layer, imagewise exposes its surface to form an electrostatic latent image, and visualizes the latent image with toner, at least the concave portion of the fine irregularities of the surface protective layer. An image forming apparatus comprising: a liquid coating device for sealing the pores with a liquid material that prevents adhesion and deposition of hydrophilic substances generated by ozone. (2) The liquid materials include an antioxidant solution, an antioxidant-containing isoparaffinic hydrocarbon solution, an antioxidant-containing aliphatic hydrocarbon solution, an antioxidant-containing silicone oil, an isoparaffinic hydrocarbon solution, and an aliphatic hydrocarbon solution. The image forming apparatus according to claim 1, wherein at least one of a hydrocarbon solution and silicone oil is used.