JPH0311373A - Image forming device - Google Patents

Abstract

PURPOSE:To effectively prevent toner and other foreign matter from adhering to an electrostatic charging roller and the wrinkle of an electrostatic charging belt from occurring and to stably obtain a good-quality image for a long time by arranging a cloth-like cleaning means which rubs the electrostatic charging belt so that it may abut on the belt. CONSTITUTION:The electrostatic charging belt 2 is laid between a pair of rollers and the belt 2 is made to abut on a photosensitive body 1 so as to travel at an appropriate relative speed. The surface of the photosensitive body 1 is electrostatically charged uniformly with bias voltage impressed on the belt 2 by a power source through the roller. A cleaning belt 3 made of cloth in a winding system or an endless belt like cleaning belt 4 made of cloth is made to abut on the belt 2 and allowed to perform a cleaning action by rubbing the belt 2 at the appropriate relative speed in a forward direction or an opposite direction. Thus, the electrostatic charging belt 2 is always kept in an excellent state and the good-quality image is stably obtained for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention (Field of Industrial Application) The present invention relates to an image forming apparatus using an electrostatic transfer process, such as an electrostatic copying machine and a printer thereof.

(Prior art and problems to be solved) A photosensitive layer on the surface of an image carrier is uniformly charged by a charging means, and optical image information is given to this to form an electrostatic latent image. Conventionally, there has been an image forming apparatus that repeats the process of supplying a toner of a shape to visualize the latent image to form a toner image, and then electrostatically transferring the toner image to a sheet-like transfer material such as paper. It is well known that it is widely used in practice.

In such devices, it is well known that selenium, cadmium sulfide, zinc oxide, etc. are used as inorganic photoconductive materials as photoconductive materials used as photosensitive layers. More and more organic compounds are being used.

Examples of this type of substance include organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene, and low-molecular-weight substances such as carbazole, anthracene, pyrazolines, oxadiazoles, hydrazones, and polyallylalkanes. Organic photoconductive members, and organic dyes and pigments such as phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes, and methine squaric acid dyes are used. These materials are being used more and more frequently because they are easier to synthesize than the above-mentioned inorganic materials, and it is easier to form materials that exhibit photoconductivity in an appropriate wavelength range.

For example, US Patent Nos. 4,123,270 and 42,516
No. 13, No. 4251624, No. 4256821, No. 4
No. 260672, No. 4268596, No. 4278747
No. 4,293,628 and the like disclose a photosensitive layer in which a photosensitive layer is functionally differentiated into a charge generation layer and a charge transport layer, in which a disazo pigment exhibiting photoconductivity is used as a charge generation layer in a photoreceptor.

In an image forming process using such a photoreceptor, the means for charging the photoreceptor is to apply a high voltage of about 5 to 8 KV DC to the wire of a charger made of stretched metal wire, and charge it with corona generated. There were many things to do.

However, this type of means generates ozone and nitrogen oxides accompanying corona discharge, which can damage the photoreceptor itself or adhere to it and cause deterioration of image quality. The amount of the law itself flowing in the direction of the photoreceptor is 5~
There were problems such as low efficiency, which was only 30%.

In order to avoid these drawbacks, a direct charging method has recently been proposed in which a charging member is brought into direct contact with a photoreceptor.

As a direct charging method, a method has been proposed in which a charging roller, belt, etc. is brought into contact with the photoconductor, and a voltage that is a combination of direct current and alternating current is applied to these charging members in order to avoid uneven charging and dielectric breakdown. (Refer to Japanese Patent Application No. 61-298419).Charging belts are preferable because they allow relatively flexible contact area and shape with the image bearing member, but on the other hand, since the belt is thin, it is difficult to clean it if paper dust or the like adheres to it. There are problems that are difficult.

By using such a charging belt, charging efficiency can be improved, but repeated use can cause deposits such as fine paper powder, rosin, and talc generated from paper, which is often used as a transfer material, or nitrogen. It is unavoidable that oxides etc. adhere to the charging belt, and since the charging belt is electrically charged, it may attract dust, toner, etc. floating in the device, resulting in uneven charging. Furthermore, these foreign substances contaminate and damage the image carrier, resulting in image defects such as image deletion, blurred images, and streak-like image disturbances.If a rubber blade is used to remove these foreign substances, The charging belt may become wrinkled and become unable to charge, which may also cause image defects.

The present invention has been made in order to cope with the current situation, and in an image forming apparatus that uses a charging belt as a direct charging means, it is possible to maintain the charging belt in a good condition at all times and to stably maintain it over a long period of time. The object of the present invention is to provide an image forming method that can obtain high-quality images.

(2) Structure of the invention (technical means for solving the problem, its effect) In order to achieve the above object, the present invention provides a primary charging belt and/or a transfer charging belt that is brought into contact with an image bearing member. , the belt is characterized by being made of a cleaning cloth material in contact with the belt.

With this configuration, in the above-mentioned image forming apparatus, it is possible to prevent the charging belt from wrinkling and to achieve uniform charging. Damage and image quality deterioration caused by the damage can be effectively prevented, and high-quality images can be obtained, and this method is particularly suitable when an organic photoconductor is used.

(Description of Embodiments) FIGS. 1 and 2 are explanatory diagrams showing an embodiment in which the present invention is applied to an image forming apparatus using a rotating cylindrical photoreceptor.

A pair of rollers are disposed near a rotating photoreceptor 1 that has an axis perpendicular to the plane of the paper and rotates in the direction of the arrow in the drawing, and a charging belt 2 is wound around these rollers. The belt 2 is caused to come into contact with the belt 2 and run at an appropriate relative speed, and the surface of the photoreceptor 1 is uniformly charged by a bias voltage applied to the belt 2 via a roller by a power source (not shown). shall be.

In an actual image forming apparatus, as the photoreceptor 1 rotates, an electrostatic latent image is formed on its surface, a toner image is formed, the toner image is transferred to a transfer material, and
Processes such as cleaning residual toner are carried out, and the necessary image information imparting means, developing device, transfer charger,
It goes without saying that cleaning devices and the like are provided, but they are all omitted.

As shown in the first figure, a retractable cloth cleaning belt 3 is brought into contact with the charging belt 2, or a second
As shown in the figure, an endless belt-like cleaning belt 4 made of cloth is brought into contact with the charging belt 2 and rubbed against the charging belt 2 at an appropriate relative speed in the direction or in the opposite direction to produce a cleaning action.

As the photoreceptor 1, an organic photoreceptor, a zinc oxide photoreceptor, a selenium photoreceptor, an amorphous silicon photoreceptor, etc. can be used. When the contact charging method is adopted, the surface deteriorates due to the generation of ozone, and image defects such as image blurring and image deletion are likely to occur.However, the present invention is most suitable for use in such organic photoreceptors. I can say that.

The structure of the charging belt 2 is preferably such that a metal vapor-deposited film is formed on the surface of a belt-like support, a conductive rubber layer is formed thereon, and a surface resistance layer is further formed thereon.

Plastic film, rubber,
Metal etc. are used.

As the metal vapor deposition film, metals such as iron, copper, stainless steel, and aluminum are used.

The conductive rubber layer can be made of rubber in which conductive particles are dispersed, such as carbon particle-dispersed EPDM rubber, aluminum particle-dispersed chloroprene rubber, or zinc particle-dispersed urethane rubber.

The surface resistance layer has a volume resistance value of 106 to 1QliilΩcI
No. 11 resin or a conductive particle-dispersed resin whose resistance is adjusted within this range is used.

As the resin, nylon, cellulose, polyvinyl pyrrolidone, polyvinyl pyridine, etc. are used, and as the conductive particle dispersion resin, metal particles such as aluminum, tin, zinc, etc., metal oxide particles such as tin oxide, antimony oxide, etc. Those dispersed in a resin such as polyvinyl butyral, polyvinyl acetal, polycarbonate, polyarylate, polymethyl methacrylate, nylon, cellulose, etc. and adjusted to the volume resistivity as described above can be used.

The thickness of this surface resistance layer is appropriately selected and formed within the range of 5 to 500 um, preferably 20 to 200 um.

When a transfer belt is used as the transfer means, a belt similar to the above-mentioned primary charging belt or an insulated belt is used.

Insulating belts include PET, PBT%PvF, and PVD.
F etc. are raised.

For the cloth cleaning belt, natural fibers and organic resin fibers can be used.

As natural fibers, cotton, wool, silk, cellulose, linen, etc. can be used.

Examples of organic resin fibers include acrylic, nylon, polyester, and polyurethane fibers.

The means for forming the cloth may be either a woven fabric or a non-woven fabric, and may be either a winding method as shown in FIG. 1 or an endless belt method as shown in FIG. Although it may be run in either forward or reverse direction as long as it has an appropriate relative speed with the belt, running in the reverse direction is more suitable for cleaning effects.

The winding method has an excellent cleaning effect because the new surface of the cleaning member is always in contact with the charged belt.If it is an endless belt, it can be improved by keeping the running speed as slow as possible and replacing it in a timely manner. You can expect a leaning function.

By disposing a cleaning means having the structure described above as a cleaning means on the charging belt, it is possible to prevent wrinkles from occurring even when using a contact charging means, especially a charging belt, and to enable uniform charging. This makes it possible to avoid contamination of the charging belt due to adhesion of toner, paper dust, and other foreign matter, and image defects such as image deletion and image blur caused by this.

Not only can a good charging function be maintained over a long period of time, but also damage to the charging belt and photoreceptor can be prevented.

Furthermore, when this charging belt is placed at a transfer site and used as a transfer charging means, the transfer material can be conveyed smoothly.
High quality images can be obtained.

Next, an experimental example to which the present invention is applied will be explained.

Experimental Example 1 An aluminum cylinder with a wall thickness of 0.5 mII+, a diameter of 60 mm, and a length of 260 nm was used as a substrate, and 4 parts of copolymerized nylon (trade name: CM8000, manufactured by Toshishiku Co., Ltd.) and type 8 nylon (trade name: Laczcamide) were used as a substrate. 500
3. 4 parts (manufactured by Dainippon Ink Co., Ltd.) and 50 parts of methanol,
It was dissolved in 50 parts of n-butanol and applied to the conductive layer by dip coating to form a polyamide undercoat layer having a thickness of 0.6 μm.

10 parts of a disazo pigment having the following structural formula and 1 part of polyvinyl butyral resin (trade name: S-LEC BH2, manufactured by Block Chemical Co., Ltd.) were dispersed together with 120 parts of cyclohexanone in a sand mill for 10 hours.

Thirty parts of methyl ethyl ketone was added to this dispersion and coated on the undercoat layer to form a charge generating layer with a thickness of 0.15 μm.

Polycarbonate Z resin (manufactured by Mitsubishi Gas Chemical Co., Ltd.)
Ten parts of a compound having a weight average molecular weight of 120,000 were prepared and dissolved in 80 parts of monochlorobenzene together with 10 parts of a hydrazone compound having the following structure.

This was coated on the charge generation layer to form a charge transport layer with a thickness of 16 μm to prepare an organic photoreceptor.

The charging belt 2 has a circumferential length of 100 mm and a width of 260 mff.
Using the stainless steel belt of No. 1 as a base layer, 100 parts by weight of Lower Brane rubber and 5 parts of conductive carbon were melt-kneaded on the surface to give a specific resistance of 3XIO'Ω in an environment of 22°C and 60% RH.
A conductive layer was formed by injection molding a conductive rubber adjusted to cII.

Furthermore, 10 parts by weight of methoxymethylated nylon 6 (methoxymethylation rate 20%) was dissolved in 90 parts by weight of methanol, and this solution was spray applied to the surface of the conductive layer so that the thickness after drying was 200 uts. A resistive layer was formed (the specific resistance of this resistive layer was 9XIO10Ωcm), and the charging belt 2 was constructed from each of these layers.

Although stainless steel was used as the support here, as mentioned above, a support made of plastic or the like with metal vapor-deposited on its surface can also be used.

The above-mentioned charging belt 2 is suspended on a pair of rollers as shown in the third figure, and includes a photoreceptor 1, a photoimage forming means 12, a developing device 5, a transfer charger 7, a cleaner 8, and a pre-static eliminating means 9. Built into a copying machine equipped with
A rollable cotton nonwoven fabric having a total length of 10 m was attached for cleaning the secondary charging belt 2, as shown in the figure.

With this configuration, the charging exposure conditions are as follows.

For the next charging, DC -750V and AC with a peak-to-peak voltage of 1500V are applied superimposed to the charging belt, and for transfer charging, 15KV is applied by a corona discharger, and the image exposure amount is lO
Regarding the evaluation of the photoreceptor potential and image, the changes in characteristics were investigated at the initial stage and after 4000 passes, and the results are shown in Table 1.

The environmental conditions at this time were 30° C. and 90% RH.

Experimental example-2 As a cleaning material, thickness 100mm, width 220wr
The experiment was conducted under the same conditions as in the above experimental example, except that an endless belt made of cotton fabric with a total length of 500 ffiI11 was used, and the results are shown in Table 1.

Comparative Example-1 As a cleaning member for charging belt, film thickness 100
Paper passing was carried out under the same conditions as in the above experimental example except that an EPDM rubber blade (JIS A hardness 30°) with a diameter of 0u111 and a free length of 10+m was used, and the results are shown in Table 1.

From this table, it was confirmed that by disposing a scraper on the charging belt, there was less potential fluctuation even after the sheet was passed, and the occurrence of image deletion was suppressed, so that good image quality could be maintained.

In particular, a scraper made of organic resin is less likely to cause scratches and can suppress the occurrence of glare. As shown in FIG. 4, the charging belt is used as a transfer means of a copying machine, and has a thickness of 200μ, a width of 220mm, and a total length of 10mm.
A roll-up type wool nonwoven fabric of 1.0 m was attached as a cleaning means for the transfer charging belt 11. .

Around the photoreceptor 1, as is well known, - a wide charger 10;
Image information providing means 12, developing device 5, cleaner 8. A pre-exposure means 9, etc. are provided, and a secondary charge of -6 KV is applied, a direct current of -100 OV is applied to the transfer belt as a transfer bias, image exposure is NIO lux/second, pre-exposure amount is 30 lux/second, and the temperature is 30. The paper was passed 4,000 times in an environment of 90% RH and the photoreceptor potential, and changes in characteristics were observed in terms of photoreceptor potential and image evaluation.

Experimental example-4 As a cleaning member used for the transfer belt 2, a thickness of 1
Except for using a belt-type wool woven cloth with a size of 50u+n, width 220mm, and total length 500mm, the same equipment as in Experimental Example 3 was used, and the same conditions were arranged as shown in Figure 7.
The paper was passed through and the photoreceptor potential and image were evaluated.

Comparative Example 2 A paper passing experiment similar to that in Experimental Example 3 above was conducted, except that a scraper was not used on the transfer belt, and the photoreceptor potential fluctuation and image were evaluated.

The results of the paper passing experiments using Experimental Examples 3 and 4 and Comparative Example 2 are shown in Table 2.

From this table, it was confirmed that by attaching a scraper to the transfer belt, there was little variation in the potential of the photoreceptor until the final stage, and no image deletion occurred.

(Margin below) Experimental example-5 A photoreceptor similar to Experimental Example 1 and a thickness of 100 μm.

A PET charging belt with a total circumference length of 100 mm and a medium diameter of 260 mm was prepared, and as shown in FIG. 5, it was arranged at the upper side of the figure as a secondary charging belt and at the lower side of the figure as a transfer charging belt.

Each belt has a thickness of 200μ and a width of 220μ as shown.
A roll-up type polyester nonwoven fabric having a total length of 5 m and a total length of 5 m was attached to each of the secondary charging and transfer charging belts as a cleaning means.

In the primary charging, a DC voltage of -750 V and an AC voltage between peaks of 1500 V are superimposed and applied to the charging belt 2, and as a transfer bias, a DC voltage of -1000 V is applied to the transfer belt, and the image exposure amount is 10 lux/sec. At a pre-exposure of 30 lux/sec, changes in the characteristics of the photoreceptor potential and images were investigated at the initial stage and when paper was passed 400 times. The environmental conditions at this time are 3
The temperature was 0°C and 90% RH.

Experimental Example 6 A photoreceptor similar to Experimental Example 5, a secondary charging belt, and a transfer charging belt were prepared, and a thickness of 15 mm was used as a cleaner for each belt.
An experiment was conducted and evaluated under the same conditions as in Experimental Example 5, except that an endless belt-like polyester woven fabric having a width of 220 mm and a total length of 500 mm was used.

Comparative Example 3 Paper was passed under the same conditions as in Experimental Example 5, except that no cleaning means was used for either the primary charging belt 2 or the transfer belt.

The results of the above Experimental Examples 5 and 6 and Comparative Example 3 are shown in Table 2.

From this result, it was found that by applying the cleaning means according to the present invention to the belt for secondary charging and transfer, it is possible to significantly reduce the potential fluctuation of the photoreceptor at the final stage, and prevent the occurrence of image deletion and damage to the photoreceptor. It has been confirmed that the prevention is also effective.

(3) As described in detail, according to the present invention, in an image forming apparatus that uses a charging belt as a contact charging means for subsequent charging, transfer charging, or both, this is applied to the charging belt. By placing a rubbing cloth-like cleaning means in contact with the charging roller, it is possible to effectively prevent toner and other foreign matter from adhering to the charging roller and from causing wrinkles on the belt. It also prevents image deterioration due to adhesion to the photoreceptor and greatly contributes to stably obtaining high-quality images over a long period of time.

[Brief explanation of drawings]

1 and 2 are schematic side views of the main parts of an image forming apparatus showing an embodiment of the present invention, and FIG. 3 shows an embodiment in which a retractable cloth cleaning member is used for the charging belt in the primary charging region. 4 is a schematic side view of an image forming apparatus showing an embodiment in which a retractable cleaning member is used for the charging belt at the transfer site; FIG. 5 is a schematic side view of the image forming apparatus showing the primary charging site and the transfer charging site. FIG. 6 is a schematic side view of an image forming apparatus showing an embodiment in which a retractable cleaning member is used for the charging belt; FIG. 6 is a schematic side view of an image forming apparatus showing an embodiment in which an endless cloth cleaning member is applied to the primary charging region 7 is a schematic side view of an image forming apparatus showing an embodiment in which an endless cleaning member made of cloth is applied to the transfer region; FIG. 8 is a schematic side view of an image forming apparatus in which a cleaning member made of cloth is applied to both the primary charging region and the transfer charging region. 1 is a schematic side view of an image forming apparatus showing an example. ■... Photoreceptor, 2... Charging belt, 3... Winding type cleaning member, 4... Winding type cleaning member, 5... Developing device, 7... Transfer charger, 8 . . . Cleaning device, pre-discharge lamp, 10 .--wide charger, 11 . . . Transfer recharging belt, 2 . . Optical image signal applying means. Ken 11 power Ken 21 M'''l +71 Kertri

Claims (3)

[Claims] (1) An image forming apparatus in which a primary charging belt and/or a transfer charging belt are brought into contact with an image carrier, and a cleaning cloth material is brought into contact with the belt. (2) Claim 1, in which the cleaning cloth material is arranged in a winding manner so as to sequentially contact the charging belt.
The image forming apparatus described in . (3) The image forming apparatus according to claim 1, wherein the cleaning cloth material is formed as an endless belt.