JPH03152584A - Electrophotographic copying device - Google Patents

Abstract

PURPOSE:To always perform stable cleaning in which abrasion and scrape caused by a cleaning blade or toner's slipping off does not occur by bringing a belt-like cleaning member into contact with an image carrier and providing a mechanism which performs exposure from the back side of a part where they contact. CONSTITUTION:Cleaning is performed by bringing the belt-like cleaning member 3 into contact with the image carrier 1. Then, the mechanism 11 which performs the exposure from the back side of the part where the belt-like cleaning member 3 is brought into contact with the image carrier 1 is provided. Namely, the endless belt-like cleaning member 3 moves in a direction opposite to the rotating direction of the image carrier 1 and rubs the image carrier 1. As a result, residual toner is cleaned out from the surface and the image carrier 1 is exposed from the back side during the cleaning to negate residual charge on the image carrier 1. Even when the abutting pressure between the image carrier 1 and the belt-like cleaning member 3 is small, a sufficient cleaning effect is accomplished and the scrape of the image carrier 1 is suppressed to be small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus using an electrophotographic process such as an electrophotographic copying machine and a printer, and particularly to a cleaning mechanism thereof.

[Prior Art] In a well-known image forming apparatus that repeats the process of transferring a toner image electrostatically formed on an image carrier onto a sheet-like transfer material mainly made of paper, the total amount of toner used to form the toner image is Since the toner is not necessarily transferred to the transfer material each time the toner is transferred, it is essential to sufficiently remove the residual toner remaining on the surface of the image carrier each time the toner is transferred.

Conventionally, as a cleaning means for this purpose, a cleaning blade made of an elastic material such as rubber is used, and the cleaning blade is configured to press against one edge of the image carrier surface to scrape off the toner that reaches this area. It is well known that this technology has been widely put into practical use. The reason for this is that it has a simple structure, low cost, and has an excellent toner removal function.

This will be explained below based on the figures.

FIG. 2 is a schematic representation of a typical example of such a leaning device, which extends in a direction perpendicular to the plane of the paper.
A cleaning mechanism 2 is arranged close to and parallel to the axial direction of a cylindrical image carrier 1 that rotates in the direction of the arrow. One edge 12a of the free edge of the cleaning blade 12 attached to the mechanism and extending in the direction perpendicular to the plane of the paper is in contact with the surface of the image carrier 1, and is not attached to the transfer site (not shown) without contributing to the transfer. When the toner remaining on the surface of the image carrier reaches the contact edge 12a of the blade 12 as the image carrier rotates, it is scraped off. The other end of the cleaning blade 12 is fixed to the support member 4. The other end of the cleaning blade 11 is fixed to the support member 4.

At this time, a method in which the free edge of the cleaning blade 12 is brought into contact with the image carrier 1 in the direction shown in the figure (counter direction with respect to the rotational direction of the image carrier 1) is effective for removing toner and is generally adopted. However, on the other hand, it has the following drawbacks.

That is, the contact edge 12 of the cleaning blade 12
In order for a to perform a stable cleaning function, it is necessary to abut the surface of the image carrier with uniform pressure over its entire length. However, toner may be fused onto the surface of the image carrier 1 due to use, and corona products, paper dust, and deposits from this may adhere to the image carrier 1 due to the presence of high-voltage members in the device. This inevitably causes unevenness on the surface of 1.

For this reason, the friction between the cleaning blade (hereinafter sometimes simply referred to as "blade") and the surface of the image carrier becomes extremely large, causing the end of the blade 12 to become stuck as shown in FIG. (There were cases where the rear edge 12b came into contact with the rear edge 12b. As a result, the cleaning function was sometimes lost. Especially when the photosensitive layer on the surface of the image carrier l is formed of an organic semiconductor, Since the friction between the cleaning blade 12 and the cleaning blade 12 is inherently large, the end of the blade tends to curl up.

In addition, it has been found that in the case of non-magnetic developers, which have come into widespread use as multi-color copying has become popular in recent years, poor cleaning and blade curling tend to occur from both ends of the blade 12. There is.

In cleaning using a cleaning blade, toner may slip through due to damage or vibration of the blade, resulting in poor cleaning.

Particularly in blade cleaning when toner with a small average particle size is used, toner tends to slip through. Further, due to the small particle size of the toner, the specific surface area of the toner becomes large, resulting in a state in which toner aggregation is likely to occur due to moisture absorption or the like. When toner aggregates at the edge of the cleaning blade, the absolute amount of toner, which also acts as a lubricant between the blade and the photoconductor, decreases, causing increased friction, which causes the cleaning blade to turn over. When a toner with such a small average particle size is used, poor cleaning is likely to occur due to toner slipping through or blade turning over (as a result, it becomes difficult to obtain stable and durable images).

Further, in cleaning using a blade, since the coefficient of friction between the cleaning blade and the image carrier is large, the image carrier is likely to be worn out during a paper passing durability test. In particular, organic photoreceptors, which are inferior to inorganic photoreceptors in terms of abrasion resistance, are easily scratched, making it difficult to obtain stable images over a long period of time in paper-running durability tests.

In order to avoid such drawbacks, for example, Japanese Patent Application Laid-Open No. 61-212
As seen in Japanese Patent Application No. 881, etc., a structure has been proposed in which both ends of the blade that come into contact with the image carrier are cut off, but with such means, the toner that runs sideways to both ends is removed from the ends. There was no escape from defects that caused the particles to scatter and contaminate the transfer material and the inside of the device.

[Problems to be Solved by the Invention] The present invention has been made to deal with the above-mentioned situation, and is capable of always performing stable cleaning without causing the cleaning blade to turn over or toner to slip through in the cleaning mechanism. The object of the present invention is to provide an electrophotographic device.

Another object of the present invention is to provide an electrophotographic apparatus in which wear and abrasion of an image bearing member in a cleaning mechanism can be reduced.

[Means for Solving the Problems] In order to achieve the above object, the present inventors have developed an electrophotographic cleaning mechanism that cleans a belt-like cleaning member by bringing it into contact with an image carrier. We have completed an improved device equipped with a mechanism that exposes the member from the back surface at the part that contacts the carrier.

This improvement improves the cleaning performance on the image carrier, and also prevents the blade from turning over, which occurs during blade cleaning.

The configuration of the present invention will be explained below based on the drawings.

The electrophotographic apparatus of the present invention is a cleaning mechanism for electrophotography that cleans an image carrier by bringing it into contact with a belt-shaped cleaning member 3. At a portion where the belt-shaped cleaning member 3 contacts the image carrier 1, the belt-shaped cleaning member 3 is exposed from the back surface of the member 3. It is characterized by having a mechanism 11 for

FIG. 1 is a schematic cross-sectional view showing the configuration of an electrophotographic apparatus according to the present invention.

A cleaning mechanism 2 is disposed close to and parallel to the axial direction of a cylindrical image carrier 1 that extends perpendicular to the plane of the paper and rotates in the direction of the arrow. It is in contact with the surface of the image carrier 1. The member 3 is supported on four support rollers 4.

In the cleaning mechanism 2, a lamp (static elimination lamp) 11 is installed on the back side of the belt-shaped cleaning member 3 and the image carrier 1 at the area where the belt-shaped cleaning member 3 and the image carrier 1 come into contact with each other. The mechanism is such that the image carrier 1 can be exposed to light from the back side.

At the transfer site 10, when the toner remaining on the surface of the image carrier l without contributing to the transfer reaches the cleaning mechanism 2 as the image carrier 1 rotates, it is removed by the belt-shaped cleaning member 3 in the mechanism 2. Cleaned (scraped).

At this time, the endless belt-shaped cleaning member 3 moves in the opposite direction to the rotational direction of the image carrier 1 and rubs the image carrier 1, thereby cleaning the residual toner on the surface of the image carrier 1. The release toner is arranged to fall into the dust box 13.

In the present invention, in particular, an exposure mechanism 11 is attached to the back side of the belt-shaped cleaning member 3, and the image carrier 1 is exposed to light at the same time as being cleaned.

In the case of a normal cleaning mechanism 2, charges remain on the unexposed portions of the image carrier 1 during cleaning, but when the cleaning mechanism 2 of the present invention is used, the image carrier 1 remains unexposed during cleaning. By exposing the body 1 to light from the back side, residual charges on the image carrier 1 are canceled out. As a result, the cleaning performance for toner is improved.

That is, when the cleaning mechanism of the present invention that exposes the belt-shaped cleaning member from the back side is installed, a sufficient leaning effect can be achieved even if the contact pressure between the image carrier 1 and the belt-shaped cleaning member 3 is smaller than that in the conventional case. This allows the image carrier 3 to be less likely to be scratched even if repeated image display durability tests are performed.

Examples of the belt-like cleaning member 3 in the cleaning mechanism 2 of the present invention include sheet-like members made of materials such as organic resins, inorganic resins, metals, or ceramics, and woven or nonwoven fabrics made of fibers. As an organic resin material,
In the case of a film or sheet, examples include polyolefin, polyvinyl chloride, polyamide, etc., and in the case of woven or nonwoven fabric, polyester, nylon, polyacrylonitrile, polymethyl methacrylate, polyurethane, etc. can be exemplified.

The lamp (discharge lamp) 11 on the back side of the belt-shaped cleaning member 3 in the cleaning mechanism 2 may be a xenon lamp, a fuse lamp, a halogen lamp, an LED, or the like.

The lamp 11 may be located inside or outside the loop of the belt-like cleaning member 3 as long as it is located in a place where it can be exposed to light from the back side of the belt-like cleaning member 3.

Examples of photoreceptors to which the cleaning mechanism of the present invention can be effectively applied include silicon photoreceptors and other organic photoreceptors. Other examples include inorganic photoreceptors made of selenium, zinc oxide, cadmium sulfide, selenium-tellurium, selenium-arsenic, and the like.

Examples of organic photoreceptors include organic photoconductive polymers such as poly-N-vinylcarbazole and polyvinylanthracene, and low-molecular organic photoconductors such as carbazole, anthracene, pyrazolines, oxadiazoles, hydrazones, and polyarylalkanes. Organic pigments and dyes such as phthalocyanine pigments, azo pigments, cyanine pigments/polycyclic quinone pigments, perylene pigments, indigo dyes, thioindigo dyes, and squaric acid methine dyes are known. In particular, organic pigments and dyes with photoconductivity are easier to synthesize than inorganic materials, and the flexibility has been expanded to allow selection of compounds that exhibit photoconductivity in an appropriate wavelength range. Many photoconductive organic pigments and dyes have been proposed.

For example, U.S. Pat. No. 4.123.270, 4.247
．． No. 614, No. 4,251,613, No. 4,251,6
No. 14, No. 4,256,821, No. 4,260,672, No. 4,268,596, No. 4.278.747, 4,
As disclosed in specifications such as No. 293,628, an electrophotographic photoreceptor using a disazo pigment exhibiting photoconductivity as a charge generation substance in a photosensitive layer functionally separated into a charge generation layer and a charge transport layer is known. It is being

Embodiment 1 A polyethylene sheet is used as the belt-shaped cleaning member 3 of the cleaning mechanism 2 shown by reference numeral 3 in FIG. The cleaning mechanism 2 was installed inside the member 3.

The image carrier 1 on which the belt-shaped cleaning member 3 in the cleaning mechanism 2 came into contact was an aluminum cylinder with a diameter of 80 mff1, on which a photosensitive layer having the following structure was formed.

Ammonia aqueous solution of casein (11.2 g of casein, 1 g of 28% ammonia water) was placed on the surface of the cylinder.

222 ml of water was applied by a coating method and then dried to form a subbing layer with a coating weight of 1.0 g/m''.

Next, 1.0 parts by weight of a charge-generating substance represented by the formula below, 1 part by weight of butyral resin [trade name: S-LEC BM-2 (manufactured by Block Chemical Co., Ltd.) 1] and 30 parts by weight of isopropyl alcohol were mixed for 4 hours using a ball mill disperser. This dispersion was applied onto the undercoat layer by a dip coating method and dried to form a charge generation layer. The thickness of the obtained layer was 0.3 μm.

Next, 1 part by weight of a charge transport substance represented by the following formula, 11 parts by weight of a polycarbonate resin [trade name: Niepilon (manufactured by Mitsubishi Gas Chemical)] and 6 parts by weight of dichloromethane were mixed and dissolved under stirring using a stirrer. This solution was applied onto the charge generation layer by dip coating and dried to form a charge transport layer. The thickness of the obtained layer was 17 μm.

This photoreceptor drum will be referred to as "photoreceptor 1."

The photoreceptor 1 created in this way and the cleaning mechanism 2 described above
A copying machine [
NP-3525 (manufactured by Canon ■)], no cleaning defects occurred, and an image equivalent to the initial image could be obtained even after 100,000 sheets were passed.

Also, the film thickness of the charge transport layer after the 50,000-sheet durability test was 16.8
It was μm. That is, the abrasion of the layer remained at 0.2 μm.

Example 2 A cleaning mechanism similar to that of Example 1 was used except that the belt-shaped cleaning member 3 in the cleaning mechanism 2 of Example 1 was changed to a polymethyl methacrylate (PMMA) fabric. Using this cleaning mechanism 2 and the same toner for the photoreceptor 1 as in Example 1, a durability test was conducted in the same manner as in Example 1. The results are shown in Table 1.

In the present invention, the belt-shaped cleaning member 3 is attached to the image carrier 1.
In an electrophotographic cleaning mechanism that performs cleaning by contacting the belt-like cleaning member 3 with the image carrier 1, it is characterized by having a mechanism that exposes the belt-like cleaning member 3 from the back surface of the member 3 at the part where the belt-like cleaning member 3 and the image carrier 1 come into contact with each other. There is a possibility that the blade may turn over as occurs in

In addition, since a blade, a roller, etc. are used, the belt-shaped cleaning member 3 is not attached to the image carrier l, unlike the conventional cleaning mechanism that has no choice but to increase the contact pressure to the image carrier.
Furthermore, due to the fact that the image bearing member 1 is exposed to neutralize electricity during cleaning, the contact pressure between the image bearing member 1 and the belt-shaped cleaning member 3 is low (although the toner can be removed efficiently (cleaning). As a result, the surface of the image carrier 1 is less likely to be scratched even after repeated and durable use.

For this reason, the cleaning mechanism of the present invention can be said to be a leaning mechanism that is particularly advantageous for organic photoreceptors that are relatively poor in abrasion resistance.

Example 3 A polyvinyl chloride (PVC) sheet was attached to the belt-like cleaning member 3 in the cleaning mechanism 2 of Example 1, and a halogen lamp was installed as the lamp 11 on the back of the belt-like cleaning member 3 inside the loop made of the member 3. It was made into a cleaning mechanism.

The image carrier 1 with which the belt-shaped cleaning member 3 in the cleaning mechanism came into contact was an aluminum cylinder with a diameter of 80 mm, on which a photosensitive layer having the following structure was formed.

Ammonia aqueous solution of casein (11.2 g of casein, 1 g of 28% ammonia water, 22% water)
2m1) using the coating method and then drying to obtain a coating amount of 1
．． A subbing layer of 0 g and 7 m'' was formed.

Next, 1.0 part by weight of a charge-generating substance represented by the following formula, 1 part by weight of a charge-transporting substance represented by the following formula, and butyral resin [trade name Kosuretsuku BM-2 (manufactured by Block Chemical Co., Ltd.)] 11
The weight and 30 parts by weight of isopropyl alcohol were mixed and dispersed for 4 hours using a ball mill dispersion machine, and this dispersion was applied onto the undercoat layer by a dip coating method and dried to form a charge generation layer. The thickness of the obtained layer was 0.3 μm.

Mix 11 parts by weight of polycarbonate resin [trade name: Kneepilon (manufactured by Mitsubishi Gas Chemical)] and 6 parts by weight of dichloromethane,
The mixture was stirred and dissolved using a stirrer. This solution was coated on the charge generation layer by a dip coating method and then dried to form a charge transport layer. The thickness of the obtained layer was 18 μm.

This photoreceptor drum will be referred to as "photoreceptor 2."

The photoconductor 2 created in this way and the cleaning mechanism 2 described above
A durability test was conducted using the same method as in Example 1.

The results are shown in Table 1 (the amount of light from the halogen lamp was adjusted to 301 ux-sec on the surface of the photoreceptor).

Example 4 The halogen lamp in the cleaning mechanism 2 of Example 3 was attached to the outside of the belt-shaped cleaning member 3, and the cleaning mechanism 2 was made of nylon fabric.

Using this cleaning mechanism 2 and the negatively charged α-3L photoreceptor, a durable image production test was conducted in the same manner as in Example 1. ``The results are shown in Table 1.

Example 5 The same photoconductor as in Example 3 was used except that the belt-shaped cleaning member 3 in the cleaning mechanism 2 as in Example 4 was replaced with a polyethylene (PE) sheet. I did an image test. The results are shown in Table 1.

[Effects of the Invention] The electrophotographic apparatus of the present invention has, as its cleaning mechanism,
We chose a method in which a belt-shaped cleaning member contacts the image carrier for cleaning, and also installed a mechanism that exposes the belt-shaped cleaning member from the back side at the part where the belt-shaped cleaning member and the image carrier come into contact, which has a synergistic effect. Because of the contribution,
Although blade cleaning may cause blade turning, good or good leaning can be performed continuously for a long period of time.

In addition, unlike cleaning mechanisms that use blades, rollers, etc., the image carrier is exposed to static electricity removal during cleaning, which is effective even when the contact pressure of the belt-shaped cleaning member against the image carrier is low. Cleaning can be carried out.

As a result, even if repeated paper passing durability tests are performed, the surface of the image carrier can be less scratched than before.

[Brief explanation of the drawing]

[Types of drawings] Fig. 1 is a schematic sectional view showing the configuration of an electrophotographic apparatus of the present invention, Fig. 2 is a partial sectional view showing the configuration of a known blade cleaning mechanism, and Fig. 3 is a schematic sectional view showing the configuration of a known blade cleaning mechanism. It is a diagram showing the contact state when the cleaning blade is engaged in the mechanism. [Main symbols in the diagram] 1... Image carrier 2... Cleaning mechanism 3... Belt-shaped cleaning member 4. ... Support member 5 ... Pre-exposure 6 ... - Medical writing device 7 ... Image exposure 8 ... Developing device 9 ... Paper feed roller 10 ... Transfer charger 11 ... Static elimination lamp 2 12a 2b ・Cleaning blade ・Abutting edge of the cleaning blade when it is normal ・Abutting edge of the cleaning blade when it is abnormal ・Dust box

Claims (1)

[Claims] (1) An electrophotographic apparatus that cleans an image carrier by bringing a belt-shaped cleaning member into contact with the image carrier, characterized in that the belt-shaped cleaning member has a mechanism for exposing a portion of the belt-shaped cleaning member that comes into contact with the image carrier from the back side of the member. Electrophotographic equipment.