JPH02272589A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent a photosensitive body from being damaged by the sticking of toner, paper powder, deposits or other foreign bodies and picture quality from deteriorating as a result and to obtain an image of good quality by making a cleaning means made of a felt material abut on an elastic electrostatic charging means. CONSTITUTION:A cleaning roller 3 made of felt or cleaning pad 4 formed of felt in a lever shape is pressed against an electrostatic charging roller 2 and rubbed against the electrostatic charging roller 2. The electrostatic charging roller 2 is made to abut on a rotary photosensitive body 1 and the surface of the photosensitive body 1 is charged electrostatically and uniformly with an applied bias voltage. Namely, the cleaning roller 3 is rotated having a proper peripheral speed difference from the electrostatic charging roller 2, and consequently respective parts of the surface of the roller is made to abut uniformly on the electrostatic charging roller 2. Consequently, the damage to the photosensitive body due to the sticking of the toner, paper powder, deposits or other foreign bodies and the resulting deterioration of the image can be precluded and the image of good quality is obtained.

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, an image forming apparatus repeats the process of supplying solid toner 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 has been widely used in practice since then.

In such devices, selenium, cadmium sulfide, zinc oxide, etc. are commonly used as inorganic photoconductive materials as the photoconductive material used as the photosensitive layer (although it is known that various materials have recently been used). 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, anddracines, and polyallylalkanes. In addition, organic dyes and pigments such as phthalocyanine pigments, azo pigments, cyanine dyes, polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes, and methine squarate 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 often to use a metal to charge the photoreceptor.

However, this type of means generates ozone and nitrogen oxides by concealing 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 charging roller, belt, etc. is brought into contact with the photoreceptor, and a voltage of DC and AC superimposed is applied to these charging members in order to avoid charging unevenness and dielectric breakdown. No. 61-298419, patent application No. 62-2
It has already been proposed, as seen in No. 3034.

By using such contact charging means, charging efficiency has been 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. Alternatively, nitrogen oxides and the like cannot be avoided from adhering to the charging means, and since the charging means is electrically charged, it may attract dust, toner, etc. floating within the device, resulting in uneven charging. Furthermore, these foreign substances contaminate or damage the image carrier, resulting in image defects such as image deletion, image blur, and streak-like image disturbance.

The present invention has been made in order to cope with such a current situation, and in an image forming apparatus using a direct charging means,
By applying a cleaning member made of felt material to the charging means, it is always maintained in a good state,
The object of the present invention is to provide an image forming method that can stably obtain high-quality images over a long period of time without causing image defects as described above.

(2) Structure of the invention (technical means for solving the problem and its operation) In order to achieve the above object, the present invention provides an image bearing member and a transfer material that is in pressure contact with the image bearing member and/or a transfer material. The image forming apparatus is equipped with a contact-type elastic charging means for applying a bias voltage, and is characterized in that a cleaning means made of felt material is brought into contact with the elastic charging means.

With this configuration, in the image forming apparatus as described above, damage to the photosensitive layer due to adhesion of toner, paper dust, precipitates, and other foreign matter and deterioration of image quality caused by this can be effectively prevented, and high quality images can be achieved. images can be obtained, and is particularly suitable when using an organic photoconductor.

(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 charging roller 2 is in contact with a rotating photoreceptor 1 having an axis perpendicular to the plane of the paper and rotating in the direction of the arrow shown in the figure. The surface shall be uniformly charged.

Although not shown, in an actual image forming apparatus, as the photoreceptor rotates 10 times, an electrostatic latent image is formed, a toner image is formed, and a toner image is sequentially formed on the surface of the photoreceptor in a well-known manner. It goes without saying that steps such as transfer to a transfer material and cleaning of residual toner are performed, and necessary image information imparting means, a developing device, a transfer charger, a cleaning device, and the like are provided.

A cleaning roller 3 made of felt, as shown in FIG. 1, or a cleaning pad 4 made of rod-shaped felt, as shown in FIG. 2, comes into pressure contact with the charging roller 2. It is arranged so that it rubs against the surface.

In the case of the cleaning roller 3, it is preferable to rotate it so as to have an appropriate circumferential speed difference with respect to the charging roller 2, so that each part of the surface of the roller contacts the charging roller 2 evenly.

With this configuration, it is possible to prevent toner and other foreign matter from adhering to the charging roller, thereby preventing contamination and damage to the photoreceptor, so that a stable charging action can be maintained at all times.

In the present invention, since felt is used as the cleaning member, there are many spaces in the fibers that make up the felt, and a large amount of toner etc. transferred from the charging roller to the felt material as a result of rubbing cleaning can be stored. Therefore, maintenance is easy.

In addition, felt is flexible and has little friction with the charging roller, which is usually made of rubber, so there is no risk of damaging the charging roller, and there is no possibility of vibrations causing uneven charging on the charging roller. .

As the photoreceptor 1, an organic photoreceptor, a zinc oxide photoreceptor, a selenium photoreceptor, an amorphous silicon photoreceptor, etc. can be used. In particular, the organic photoreceptor can be contacted by a corona charging method or by a charging roller having no cleaning means. If a charging method is used, the surface deteriorates due to the generation of ozone, and image defects such as image blurring and image deletion are likely to occur. Therefore, the present invention is said to be most suitable for use in such organic photoreceptors. I can do it.

The structure of the charging roller 2 is such that a conductive rubber layer is formed on a core made of a rigid material such as metal, and a resistance layer is formed on the surface of the conductive rubber layer.

It is preferable to use iron, copper, stainless steel, aluminum, etc. as the core metal.

The conductive rubber layer is made of rubber in which conductive particles are dispersed, and examples thereof include carbon particle-dispersed EPDM rubber, aluminum particle-dispersed chloroprene rubber, and zinc particle-dispersed urethane rubber.

For the surface resistance layer, a resin having a volume resistivity adjusted to a range of 10 6 to 10'2 Ωcm or a resin in which conductive particles are dispersed 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 within the range of 5 to 500 ulI+, preferably 20 to 200 gm.

As materials for the felt roller 3 and felt pad 4, natural fibers, organic resin fibers, and inorganic fibers can be used.

For example, natural fibers include wool, rabbit hair, goat hair, cotton,
Silk, valve, etc. can be used.

As the organic resin fiber, polyethylene, polypropylene, polyurethane, polyamide, cellulose, cellulose acetate, polyvinyl acetate, PTFE, etc. are used.

Examples of inorganic fibers include glass fibers, carbon fibers, iron fibers, and the like.

Among these, natural fibers such as rabbit wool and cotton, and organic resin fibers such as polyethylene, polypropylene, and PTFE are preferred.

If the surface layer of the charging roller is made of a soft material such as nylon or cellulose, using felt as a cleaning material with a hard inorganic material such as glass fiber, carbon fiber, or iron fiber may damage the charging roller. The combination of the charging roller and the felt cleaning member must be appropriately selected in consideration of this point.

By configuring the charging means and its cleaning means as described above, the advantages of using a contact charging means and a charging roller can be maintained, and the charging roller can be prevented from being contaminated by toner, paper dust, or other foreign matter. , image defects such as image blurring and image blurring caused by this can be avoided, and by using felt as a cleaning member, it is easy to maintain due to its large collection capacity, and it can maintain good charging performance over a long period of time. Not only can this be maintained, but also damage to the charging roller and photoreceptor can be prevented.

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

Experimental example 1 Base material: thickness 0.5n+m, diameter 60mm, length 2
Using a 60 mm aluminum cylinder, 4 parts of copolymerized nylon (trade name: CM8000, manufactured by Toshiku Co., Ltd.) and type 8 nylon (trade name: Niratsukamite 5003,
(manufactured by Dainippon Ink Co., Ltd.), 50 parts of methanol, n-
It was dissolved in 50 parts of butanol and applied to the above conductive layer by dip coating to form a polyamide undercoat layer with a thickness of 0.6 μm.

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

30 parts of methyl ethyl ketone was added to this dispersion and coated on the undercoat layer to form a charge generation 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 along 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.

A mixture of 100 parts by weight of chloroprene rubber and 5 parts of conductive carbon was melt-kneaded onto a stainless steel rod with a diameter of 5 mm and a length of 280 mm to form a conductive layer with a diameter of 201TII11 and a length of 220+ nm. The volume resistance value of this conductive layer is 3X10'Ω in an environment of 22°C and 60%RH.
It was cIm.

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 to a thickness of 200 μm.
A surface resistance layer of m was formed.

The volume resistivity value of this surface resistance layer was 9×10”ΩcI11.

The photoconductor 1 and charging roller 2 configured as shown in FIG. A roller 3 made of wool felt and having a diameter of 110 lTl was brought into contact with the charging roller 2 and rotated in the forward direction to form a cleaner.

With this configuration, the charging exposure conditions are as follows: -750V DC and 150V peak-to-peak voltage on the charging roller for the next charging.
An alternating current of 0 V was applied in a superimposed manner, 15 Kv was applied by a corona discharger as a transfer charge, the exposure amount was 10 lux·sec, and the pre-exposure was 30 lux·sec. Changes in properties after paper were investigated, and the results are shown in Table 1.

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

Experimental Example-2 As shown by reference numeral 4 in Fig. 6, the charging roller has a thickness of 3f.
An experiment was conducted under the same conditions as in Experimental Example 1 above, except that a felt pad of fII 11 and width 5 mm was placed in contact with the pad, and the results are shown in Table 1.

Comparative Example-1 An experiment was conducted under the same conditions as in Experimental Example-1 above, except that a felt cleaner was not used for the charging roller, and the results are also shown in Table 1.

From this table, it was confirmed that by disposing a felt cleaner on the charging roller, potential fluctuations were small even after paper was passed (and image deletion was also suppressed, and good image quality could be maintained).

(Leaving space below) Experimental Example 3 A photoreceptor 1 and a charging roller 2 similar to those in Experimental Example 1 were prepared, and as shown in Figure 4, they were installed in a regular development type copying machine and used as a transfer means. to the transfer roller 11,
A nylon felt roller 3 having a diameter of 20 mm was brought into contact with the roller 11 and rotated in the forward direction to form a cleaner.

Around the photoreceptor 1, a wide charger 10, an image information imparting section 4, a developing device 5, a cleaner 8, a pre-exposure means 9, etc. are arranged; Apply DC -1000 V to
The paper was passed 2,000 times in an environment of 90% RH, and changes in characteristics were observed in terms of photoreceptor potential and image evaluation.

Experimental Example 4 Paper was passed through the same apparatus and under the same conditions as in Experimental Example 3 above, except that a Teflon felt pad with a thickness of 5 mm and a width of 8 Ilffi was used as a cleaning member for the transfer roller 11. The photoreceptor potential and image were evaluated.

Comparative Example 2 A paper passing experiment was carried out in the same manner as in Experimental Example 3 above, except that a felt cleaner was not used for the transfer roller, 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 can be seen that by attaching a felt cleaner to the transfer roller, there is less potential fluctuation on the photoreceptor until the final stage.
It was confirmed that no image blurring occurred.

(Leaving space below) Experimental Example 5 A photoreceptor similar to Experimental Example 1 and two charging rollers were prepared, and as shown in FIG.
The charging roller is arranged at the upper part of the figure and used as the primary charging roller 2, and the other charging roller is arranged at the transfer site and used as the transfer roller 11.

The primary charging roller 2 is a polyethylene felt roller with a diameter of 20 mm, and the transfer roller 11 is a polyethylene felt roller with a diameter of 25 mm.
mm polyethylene felt rollers were respectively provided as cleaners, and cleaning was performed by running them in the opposite direction to the charging and transfer rollers.

In the primary charging, a superimposed DC voltage of -750V and AC voltage of 1500V between peaks are applied to the charging roller 2, and as a transfer bias, a DC voltage of -1000V is applied to the transfer roller 11, and the image exposure amount is 10 lux. seconds, pre-exposure 30 lux・
Changes in characteristics of the photoreceptor potential and images were investigated at the initial stage and after 2000 paper passes in seconds. The environmental conditions at this time were 30° C. and 90% RH.

Experimental example-6 Cylindrical rollers for primary charging and transfer charging, thickness 5 mm, width 1
Other than using a 0mm nylon 6 felt pad,
Paper was passed under the same conditions as in Experimental Example 5, and the potential fluctuation of the photoreceptor and the state of the image were examined.

Comparative Example-3 No felt cleaner was used for either the primary charging roller 2 or the transfer roller 11, except for the above experimental example-
Paper passing was carried out under the same conditions as in 5.

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

From this result, it was confirmed that the present invention is sufficiently effective in preventing the secondary charging roller, the transfer roller, image deletion, and damage to the photoreceptor.

(Margin below), the potential fluctuation of the photoreceptor at the final point is significantly reduced (3)
As described in detail, according to the present invention, in an image forming apparatus that uses a charging roller as a contact charging means for subsequent charging, transfer charging, or both, a felt member is attached to the charging roller as a cleaning means. By arranging the rollers in contact with each other, it is possible to effectively prevent toner and other foreign matter from adhering to the charging roller, prevent damage to the image carrier due to foreign matter, and prevent image deterioration due to adhesion of foreign matter. It is possible to stably obtain 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 FIGS. 3 and 6 show an embodiment in which a felt cleaning member is used in the charging roller of the primary charging region. 4 and 7 are schematic side views of an image forming apparatus showing an embodiment in which a felt cleaning member is used as a charging roller at a transfer site, and FIGS. 5 and 8. 1 is a schematic side view showing an image forming apparatus that uses felt cleaning members in a primary charging region and a transfer charging region. DESCRIPTION OF SYMBOLS 1... Photoreceptor, 2... Charging roller, 3... Felt roller, 4... Felt pad, 11... Transfer roller. Figure 6 Figure 6 People Figure 8 Figure 8

Claims (3)

[Claims] (1) An image bearing member, which is in pressure contact with the image bearing member and (
or) an image forming apparatus comprising a contact-type elastic charging means for applying a bias voltage to a transfer material, wherein a cleaning means made of felt material is in contact with the elastic charging means. (2) The image forming apparatus according to claim 1, wherein the felt material is formed into a roller shape. (3) The image forming apparatus according to claim 1, which is formed of felt material into a pad shape.