JP2003043859A - Electrophotographic device and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic device and a process cartridge having excellent electrophotographic characteristic that an image defect such as ghost is not caused in any environment and potential fluctuation is small even in the case of repetitive use. SOLUTION: This electrophotographic device is provided with a photoreceptor, an electrifying means, an information writing means, a developing means, a transfer means, a developer electrified amount control means positioned on an upstream side from the electrifying means and electrifying developer on the surface of the photoreceptor, and a residual developer image uniformizing means positioned on an upstream side from the control means and on a downstream side from the transfer means and uniformizing a residual developer image remaining on the surface of the photoreceptor after transferring the developer image to transfer material. In the device, the uniformizing means uniformizes the residual developer image remaining after transferring the developer image, the control means processes to electrify the uniformized residual developer to have normal polarity, and the electrifying means electrifies the surface of the photoreceptor and simultaneously makes the electrified amount appropriate. In the device, the aluminum base substance of the photoreceptor is ground by using abrasive liquid incorporating abrasives. Such an electrophotographic device and the process cartridge are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleanerless transfer type electrophotographic apparatus and process cartridge, and more specifically, developing and cleaning developer (toner) remaining on the electrophotographic photosensitive member after the transfer step in the developing apparatus. The present invention relates to a cleanerless type electrophotographic apparatus and a process cartridge in which a cleaning device is eliminated by removing and collecting the image bearing member from the image carrier and reusing it.

[0002]

2. Description of the Related Art Conventionally, a transfer type electrophotographic apparatus such as a copying machine, a printer or a facsimile using a transfer type electrophotographic method has a rotary drum type electrophotographic photosensitive member which is an image carrier, A charging device (charging process) for uniformly charging the photoconductor to a predetermined polarity / potential, an exposure device (exposure process) as an information writing unit for forming an electrostatic latent image on the charged photoconductor, and the photoconductor. A developing device (developing process) that visualizes the electrostatic latent image formed on the surface with toner that is a developer, a transfer device (transfer process) that transfers the toner image from a photoconductor surface to a transfer material such as paper, and transfer It is composed of a cleaning device (cleaning process) that removes a little residual toner on the photoconductor after the process to clean the surface of the photoconductor, a fixing device (fixing process) that fixes the toner image on the transfer material, and the like. Exposure Repeating electrophotographic process (charging, exposure, development, transfer and cleaning) is subjected is applied to image formation by.

Toner remaining on the photoconductor after the transfer process is removed from the photoconductor surface by the cleaning device and collected in the cleaning device to be waste toner, but this is because of environmental protection and effective use of resources. It is desirable that no waste toner is generated.

Therefore, there is an electrophotographic apparatus which returns the transfer residual toner, so-called waste toner, collected by the cleaning apparatus to the developing apparatus for reuse.

There is also a cleanerless type electrophotographic apparatus in which the cleaning device is abolished, and the transfer residual toner on the photoconductor after the transfer process is removed and collected from the photoconductor by development and reused.

In the development / cleaning, the transfer residual toner on the photoconductor after transfer is subjected to a developing process after the next process, that is, the photoconductor is continuously charged and exposed to form an electrostatic latent image. During the process of developing an image, a fog removing bias (a fog removing potential difference Vback which is a potential difference between a DC voltage applied to a developing device and a surface potential of the photoconductor is used). Part)
Since the transfer residual toner existing in 1 is collected by the developing device and reused in the development of the electrostatic latent image in the subsequent steps, it is possible to eliminate the waste toner and to reduce the troublesome maintenance. Further, the so-called cleaner-less type, which does not have an independent cleaning means, is advantageous for downsizing the electrophotographic apparatus.

A) In the cleanerless type electrophotographic apparatus in which the transfer residual toner on the photoconductor after the transfer step as described above is removed and collected by the developing device by the development / cleaning and reused, the charging device is the photosensitive member. When the contact charging device contacts the body to charge the surface of the photoconductor, the transfer residual toner on the photoconductor passes through the charging unit, which is the contact nip between the photoconductor and the contact charging device. In particular, the toner in which the charging polarity is reversed to the polarity opposite to the normal polarity adheres to the contact charging device and contaminates the contact charging device more than allowable, resulting in a charging failure.

In other words, the toner as a developer contains a mixture of toner whose charge polarity is originally reversed to the opposite polarity to the normal polarity, although the amount is small. Also,
Even for toner having a normal charging polarity, there is a toner whose charge polarity is reversed by being influenced by a transfer bias or peeling discharge, and a toner whose charge amount is reduced by being discharged.

Therefore, the transfer residual toner is a mixture of a toner having a normal charge polarity, a toner having a reverse charge polarity, and a toner having a small charge amount. Among them, the reverse toner and the toner having a small charge amount are photoreceptors. When the toner passes through the charging portion which is the contact nip portion of the contact charging device, it easily adheres to the contact charging device.

B) In addition, in order to remove and collect the transfer residual toner on the photosensitive member by the cleaning and development of the developing device, the transfer residual toner on the photosensitive member is passed through the charging unit and carried to the developing unit. It is necessary that the charging polarity is normal polarity and that the charging amount is the charging amount of the toner capable of developing the electrostatic latent image on the photoconductor by the developing device. Reversed toner and toner having an inappropriate charge amount cannot be removed / collected from the photoconductor by the developing device, which causes a defective image.

C) The toner adhered to the contact charging device of the above a) is mixed in that it is carried from the transfer section to the charging section and has a regular charge polarity, a reverse polarity, and a small charge amount. The transfer residual toner on the photoconductor is charged to the normal polarity by the toner charge amount control means so that the charge polarity is aligned to the normal polarity and the charge amount is made uniform, which can be prevented.

However, the transfer residual toner charged by the toner charge amount control means in order to prevent the toner from adhering to the contact charging device is compared with the charge amount of the toner capable of developing the electrostatic latent image on the photoconductor. Since it is large, it is difficult to be removed and collected by the developing / cleaning in the developing device. In such a case, the toner remaining on the photoconductor overlaps with the next image, resulting in a defective image.

With the diversification of user needs in recent years, a large amount of transfer can be performed at once by continuous printing operation of images with a high printing rate such as photographic images, and multiple development method on a photoconductor with colorization. The generation of the residual toner further aggravates the above problems.

On the other hand, regarding the substrate of the electrophotographic photosensitive member,
Usually, the raw material does not always have the optimum surface condition for the photoconductor in the as-processed state, so that problems often occur due to the surface condition.

In order to solve this problem, it has hitherto been known, for example, in JP-A-1-123246 and 64-861.
In Japanese Patent Laid-Open No. 53-53, a photosensitive layer is formed after cutting the surface of an aluminum substrate with a lathe. In particular, it has been proposed to prevent interference fringes by cutting the surface of a base body of a digital photoconductor into appropriate irregularities.

However, when the aluminum substrate is cut, continuous processing marks remain in the circumferential direction, so that streak-shaped image defects appear in a halftone image, and particularly, a digital image and a scanning line of a laser are formed. Moire was likely to occur from the relationship.

Further, JP-A-7-43922 and JP-A-8-1510 describe that the outer peripheral surface of the substrate is subjected to roller burnishing. This method can give irregular surface with no regularity, but because the hard grindstone is rotated at high speed to scrape the substrate surface, it is easy to get deep scratches on the surface of the cylinder due to the dropping of abrasive grains and the effect of cutting chips. However, the scratches sometimes caused image defects when the photoconductor was manufactured.

On the other hand, there is also a method in which a conductive layer is provided on the surface of the aluminum substrate to prevent interference fringes and image defects caused by the substrate. However, in a system of a cleanerless system in such a complicated electrophotographic process of charge control, there is a case where a so-called ghost phenomenon in which the influence of the previous image appears in the next development, or a potential fluctuation during repeated use may occur. It was

In this image ghost, the charge generated by exposure stays, for example, in the conductive layer on the photoconductor substrate, and at the time of the next image formation, the staying charge affects the dark part potential and the light part potential of the photoconductor. Is believed to be.

[0020]

The object of the present invention is to:
To provide an electrophotographic apparatus and a process cartridge which have good electrophotographic characteristics, in which image defects such as ghosts do not occur in any environment in a cleanerless type electrophotographic apparatus, and electric potential fluctuations are small even in repeated use. It is in.

[0021]

According to the present invention, an electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, and an information writing unit for forming an electrostatic latent image on the charged electrophotographic photosensitive member. A developing unit for supplying a developer to the electrostatic latent image to visualize the electrostatic latent image; a transferring unit for transferring the visualized developer image to a transfer material; and an electrophotographic apparatus located upstream of the charging unit. A developer charge amount control means for charging the developer on the surface of the photoreceptor, and a developer charge amount control means located upstream of the developer charge amount control means and downstream of the transfer means, after transferring the developer image to a transfer material. A residual developer image uniformizing means for uniformizing the residual developer image remaining on the surface of the electrophotographic photosensitive member,
The residual developer image remaining on the electrophotographic photosensitive member after transfer of the developer image is made uniform by the residual developer image uniformizing means, and the uniformed residual developer image on the electrophotographic photosensitive member is charged by the developer. In an electrophotographic apparatus in which an amount control means performs electrification to a normal polarity and the electrification means electrically charges the surface of the electrophotographic photoreceptor, and at the same time, an aluminum substrate of the electrophotographic photoreceptor contains an abrasive liquid. Provided is an electrophotographic apparatus and a process cartridge, which are polished by using.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in more detail below.

In the present invention, the cleaner-less type electrophotographic apparatus in which the transfer residual developer (transfer residual toner) on the electrophotographic photosensitive member after the transfer step is removed and collected by the developing means by developing and cleaning and reused. Specifically, the distribution of the transfer residual developer on the electrophotographic photosensitive member is made uniform, and the tribo of the transfer residual developer is charged to the normal polarity by the developer charge amount control means, and the proper charge amount is charged by the charging means. In this system, the aluminum base of the electrophotographic photosensitive member is polished with a polishing liquid containing an abrasive.

FIG. 3 is a schematic structural model diagram of an example of an electrophotographic apparatus according to the present invention. The electrophotographic apparatus of this example is a laser beam printer that uses a transfer type electrophotographic process, a contact charging type, a reversal development type, a cleanerless type, and a maximum sheet size of A3 size.

Next, the electrophotographic photosensitive member according to the present invention will be described in detail.

The layer structure of the electrophotographic photosensitive member according to the present invention is a layer structure having a photosensitive layer composed of a single layer containing a charge generating material and a charge transporting material simultaneously on a conductive substrate, and a charge generating on the conductive substrate. There is a layer structure having a photosensitive layer in which a charge generation layer containing a material and a charge transport layer containing a charge transport material are laminated.

FIG. 4 shows a layer structure having a photosensitive layer in which a charge generating layer containing a charge generating material and a charge transporting layer containing a charge transporting material are laminated on a conductive substrate. A structure in which three layers of a subbing layer 1b for suppressing light interference and improving adhesiveness of the upper layer, a photocharge generation layer 1c, and a charge transport layer 1d are sequentially applied from the bottom on the surface of the conductive substrate 1a. Are doing

Examples of the effective charge generating material used in the present invention include the following substances. These charge generating materials may be used alone or in combination of two or more kinds.

(1) Azo pigments such as monoazo, bisazo and trisazo (2) Indigo pigments such as indigo and thioindigo (3) Phthalocyanine pigments such as metal phthalocyanine and non-metal phthalocyanine (4) Perylene anhydride, perylene acid Perylene pigments such as imides (5) Polycyclic quinone pigments such as anthraquinone and pyrenequinone (6) Squarylium dye (7) Pyrylium salts, Thiopyrylium salts (8) Triphenylmethane dyes (9) Selenium, amorphous silicon Inorganic substances such as

The layer containing the charge generating material, that is, the charge generating layer can be formed by dispersing the charge generating material as described above in a suitable binder resin and coating this on a conductive substrate. . It can also be formed by forming a thin film on a conductive substrate by a dry method such as vapor deposition, sputtering and CVD.

The binder resin can be selected from a wide range of binder resins, for example, polycarbonate resin, polyester resin, butyral resin, polystyrene resin, polyvinyl acetal resin, diallyl phthalate resin, acrylic resin, methacrylic resin, vinyl acetate resin, Phenol resin, silicone resin, polysulfone resin, styrene-
Butadiene copolymer resin, alkyd resin, epoxy resin, urea resin, vinyl chloride-vinyl acetate copolymer resin and the like can be mentioned, but not limited to these.
These are 1 type or 2 types as a homopolymer or a copolymer polymer.
You may use it in mixture of 2 or more types.

The resin contained in the charge generation layer is preferably 80% by mass or less, and particularly preferably 40% by mass or less.
The thickness of the charge generation layer is preferably 5 μm or less, and particularly preferably a thin film layer having a thickness of 0.01 μm to 2 μm. Further, various sensitizers may be added to the charge generation layer.

The layer containing the charge transporting material, that is, the charge transporting layer can be formed by combining the charge transporting material and a suitable binder resin. Examples of the binder resin used in the charge transport layer include those used in the charge generation layer, and further include photoconductive polymers such as polyvinylcarbazole and polyvinylanthracene.

As the charge transport material, one kind may be used alone, or two or more kinds may be used in combination. Further, charge transport materials having other structures [for example, polycyclic aromatic compounds such as pyrene and anthracene, carbazole series, indole, etc.] may be used. , Oxazole-based, thiazole-based, oxadiazole-based, pyrazole-based, pyrazoline-based, heterocyclic compounds such as thiadiazole-based and triazole-based compounds, triarylmethane-based compounds, or groups containing these compounds in the main chain or side chains Polymer (eg, poly-N-vinylcarbazole, polyvinylanthracene, etc.)] and the like.

The compounding ratio of the binder resin and the charge transport material is
10-50 parts of charge transport material per 100 parts by mass of binder resin
It is preferably 0 part by mass. The charge transport layer is electrically connected to the above-mentioned charge generation layer and has a function of receiving charge carriers injected from the charge generation layer in the presence of an electric field and transporting these charge carriers to the surface. ing. Since this charge transport layer has a limit of transporting charge carriers, the film thickness cannot be increased more than necessary, but 5 μm to 40 μm is preferable, and 10 μm is particularly preferable.
The range of m to 30 μm is preferable.

When forming such a charge transport layer, a coating method such as a dip coating method, a spray coating method, a spinner coating method, a roller coating method, a Mayer bar coating method and a blade coating method is used by using an appropriate organic solvent. Can be done using.

As shown in FIG. 2, the method for producing a substrate for an electrophotographic photosensitive member of the present invention uses, as shown in FIG. Abrasive grains are discharged onto the (aluminum cylinder substrate), and after liquid honing, a photosensitive layer is formed.

The liquid honing method shown in FIG. 1 is a method in which abrasive grains are suspended in a liquid and the surface of the workpiece is roughened by projecting it from the tip of a thin nozzle 21 with air pressure to roughen the surface.
Generally, water is used as the medium, and alumina, zirconia, stainless beads, or the like is used as the medium (abrasive grains). The particle size of the abrasive grains used for this liquid honing is about 5 μm to several hundreds μm. These types, particle sizes, etc. are properly used according to the purpose of use.

These media (abrasive grains) are mixed in a suspension medium (mainly water) at a ratio of 2% to 30%. If the ratio of the media (abrasive grains) is too small, the processing efficiency is lowered, and if the ratio is too large, the fluidity of the suspending medium is deteriorated, and the discharge amount from the nozzle is reduced or does not come out.

In the liquid honing, a liquid in which abrasive grains are suspended is circulated by a pump 31, and when the nozzle has a circular injection port shape, it is discharged from the tip of a nozzle having a diameter of 5 mm to 20 mm.
It is projected on the work piece 24, and is 5 liters per minute or more.
With a circulation volume of about 50 liters, the surface roughness does not change much even when the suspension hits the workpiece. The roughness changes greatly depending on the pressure of the air during projection. This air pressure is generally about 0.01 MPa to 0.6 MPa. Below this range, the processing efficiency tends to decrease, and above this range, the surface roughness tends to become too large.

When spherical alumina abrasive grains are used, the average particle size is 20 to 30 μm, and the particle size distribution is 2 to 40 μm.
m particle size is included. It is possible to manufacture a product having a sharp particle size distribution to some extent, but it is not possible to completely eliminate the abrasive particles having a small particle size, resulting in an increase in cost.

The closer the distance between the tip of the nozzle 21 and the work piece 24 is, the better the efficiency. However, in general, in the method of moving the nozzle 21 while rotating a cylindrical object,
If the nozzle is too close, processing irregularities will occur, so 1
Processing is performed at a distance of 0 mm to 400 mm. The moving speed of the nozzle is about 0.2 m to 2 m per minute, and a method of moving the nozzle and honing is generally used while rotating the workpiece. The higher the number of revolutions, the less the unevenness appears, but it is preferably about (1/2) s ^{-1 to} 10s ^{-1 and} is adjusted according to the moving speed of the nozzle. The abrasive particles ejected from the nozzle softly collide with the work piece due to the effect of water ejected at the same time. Therefore, the impact of the abrasive particles is less than that of the dry sandblast method that does not use a suspension medium (water),
Therefore, the roughness of the surface to be processed is smaller than that of the dry sandblasting method under the same conditions, and the rate of breaking of the abrasive grains is also small. In the dry sandblasting method and the liquid honing method, it is generally considered that roughening the surface is to scrape the surface, but in reality, the surface is hardly scraped, and the surface is mainly impacted by the abrasive grains. It is plastically deformed and dented. This tendency is particularly strong when spherical abrasive grains are used.

Therefore, in the dry sand blasting method and the liquid honing method, if the abrasive grains are uniformly projected onto the surface, even if the abrasive grains are applied under the same conditions, the surface roughness hardly changes.

Further, in the case of roughening by honing or blasting, if the discharge abrasive grains are applied to the surface of the work piece at a smaller angle than obliquely, the processing area at the time of spraying the abrasive grains is widened. As a result, unevenness is less likely to occur.

After the step of roughening the surface of the substrate by liquid honing, that is, the polishing step, the surface is usually washed before the photosensitive layer is formed on the substrate, and the adhered abrasive (abrasive grains), polishing liquid, dust, oil Remove system substances and human fingerprints.

Next, the cleanerless electrophotographic apparatus of the present invention will be described.

A) Charging means In FIG. 3, reference numeral 2 denotes a contact charging device (contact charging device) as a charging device for uniformly charging the peripheral surface of the photosensitive drum 1. In this example, a charging roller (roller charging device). Is.

The charging roller 2 rotatably holds both ends of the cored bar 2a by bearing members (not shown), and urges the pressing roller 2e toward the photosensitive drum to press the surface of the photosensitive drum 1. Are pressed against each other with a predetermined pressing force, and rotate following the rotation of the photosensitive drum 1. The pressure contact portion between the photosensitive drum 1 and the charging roller 2 is a charging portion (charging nip portion) a.

By applying a charging bias voltage of a predetermined condition from the power source S1 to the core metal 2a of the charging roller 2, the peripheral surface of the rotary photosensitive drum 1 is contact-charged to a predetermined polarity and potential. In this example, the charging bias voltage applied to the charging roller 2 is a DC voltage (Vdc) and an AC voltage (V
ac) is an oscillating voltage that is superimposed.

The longitudinal length of the charging roller 2 is 320 mm, and as shown in the schematic diagram of the layer structure of FIG.
2a, a lower layer 2b, an intermediate layer 2c, and a surface layer 2d.
Has a three-layer structure in which the layers are sequentially laminated from the bottom. The lower layer 2b is a foam sponge layer for reducing the charging noise, and the intermediate layer 2
Reference numeral c is a conductive layer for obtaining uniform resistance as a whole of the charging roller, and surface layer 2d is a protective layer provided to prevent leakage even if there are defects such as pinholes on the photosensitive drum 1. Is.

In FIG. 4, 2f is a charging roller cleaning member, which is a flexible cleaning film in this example. This cleaning film 2f is arranged in parallel with the longitudinal direction of the charging roller 2 and has one end fixed to a supporting member 2g which reciprocates a certain amount in the longitudinal direction, and the charging roller 2f has a surface near the free end measurement. And is arranged to form a contact nip with. Support member 2g
Is driven by a drive motor of the electrophotographic apparatus through a gear train in a reciprocating motion in the longitudinal direction by a predetermined amount, and the charging roller surface layer 2d is rubbed with the cleaning film 2f. As a result, contaminants (fine toner, external additives, etc.) attached to the surface layer 2d of the charging roller are removed.

B) Information Writing Means 3 in FIG. 3 is an exposure device as information writing means for forming an electrostatic latent image on the surface of the photosensitive drum 1 that has been subjected to the charging process.
This example is a laser beam scanner using a semiconductor laser. A laser beam modulated in accordance with an image signal sent from the host device such as an image reading device (not shown) to the electrophotographic device side is output to output the uniformly charged surface of the rotating photosensitive drum 1 to the laser at the exposure position b. Scanning exposure L (image exposure)
To do. By this laser scanning exposure L, the potential of the surface of the photosensitive drum 1 irradiated with the laser beam is lowered, so that electrostatic latent images corresponding to the image information subjected to the scanning exposure are sequentially formed on the surface of the rotating photosensitive drum 1. To go.

C) Developing Means 4 in FIG. 3 is a developing device (developing device) as developing means for supplying a developer (toner) to the electrostatic latent image on the photosensitive drum 1 to visualize the electrostatic latent image. This example is a reversal developing device of a two-component magnetic brush developing system.

Reference numeral 4a denotes a developing container, 4b denotes a non-magnetic developing sleeve, and the developing sleeve 4b is rotatably disposed in the developing container 4a with a part of the outer peripheral surface thereof exposed to the outside. 4c is a magnet roller fixed non-rotatably and inserted in the developing sleeve 4b, 4d is a developer coating blade, 4e is a two-component developer housed in the developing container 4a, and 4f is a bottom part in the developing container 4a. The developer agitating member 4g provided is a toner hopper, and contains replenishment toner.

The two-component developer 4e in the developing container 4a is a mixture of toner and magnetic carrier, and is a developer stirring member 4
Stirred by f. The toner is negatively charged by friction with the magnetic carrier.

The developing sleeve 4b is arranged facing the photosensitive drum 1 so that the closest distance (referred to as S-Dgap) to the photosensitive drum 1 is kept at 350 μm and is close to the photosensitive drum 1. The facing portion between the photosensitive drum 1 and the developing sleeve 4a is the developing portion c.
Is. The developing sleeve 4b is rotationally driven in the developing portion c in the direction opposite to the traveling direction of the photosensitive drum 1. On the outer peripheral surface of the developing sleeve 4b, the two-component developer 4e in the developing container 4a is generated by the magnetic force of the magnet roller 4c in the sleeve.
Is attracted and held as a magnetic brush layer, is rotatably conveyed as the sleeve rotates, is layered into a predetermined thin layer by the developer coating blade 4d, and contacts the surface of the photosensitive drum 1 at the developing section c. Then, the surface of the photosensitive drum is rubbed appropriately. A predetermined developing bias is applied to the developing sleeve 4b from the power source S2. In this example, the developing bias voltage for the developing sleeve 4b is a direct current voltage (Vdc).
And an alternating voltage (Vac) are superposed on each other.

The surface of the rotating developing sleeve 4b is coated with a thin layer, and the toner in the developer carried to the developing section c is converted into an electrostatic latent image on the surface of the photosensitive drum 1 by the electric field generated by the developing bias. Correspondingly and selectively adhering, the electrostatic latent image is developed as a toner image. In the case of this example, toner adheres to the exposed bright portion of the surface of the photosensitive drum 1 and the electrostatic latent image is reversely developed.

The thin developer layer on the developing sleeve 4b which has passed through the developing section c is returned to the developing agent reservoir section in the developing container 4a as the developing sleeve subsequently rotates.

In order to maintain the toner concentration of the two-component developer 4e in the developing container 4a within a predetermined substantially constant range, the toner concentration of the two-component developer 4e in the developing container 4a is, for example, an optical toner (not shown). Detected by the density sensor, the toner hopper 4g is drive-controlled according to the detected information, and the toner in the toner hopper is replenished to the two-component developer 4e in the developing container 4a. The toner supplied to the two-component developer 4e is stirred by the stirring member 4f.

D) Transfer Means / Fixing Means 5 in FIG. 3 is a transfer device, which is a transfer roller in this example.
The transfer roller 5 is brought into pressure contact with the photosensitive drum 1 with a predetermined pressing force, and the pressure contact nip portion is the transfer portion d. A transfer material (transferred member or recording material) P is fed to the transfer portion d from a paper feed mechanism (not shown) at a predetermined control timing.

The transfer material P fed to the transfer portion d is nipped and conveyed between the rotating photosensitive drum 1 and the transfer roller 5, and during that time, the transfer roller 5 is supplied from the power source S3 to the normal charging polarity of the toner. By applying a transfer bias of a positive polarity having a polarity opposite to that of a certain negative polarity, +2 kV in this example, a toner image on the side of the photosensitive drum 1 is formed on the surface of the transfer material P which is nipped and conveyed in the transfer portion d. Are sequentially electrostatically transferred.

The transfer material P which has received the transfer of the toner image through the transfer portion d is sequentially separated from the surface of the rotary photosensitive drum 1 and conveyed to the fixing device 6 (for example, a heat roller fixing device) to fix the toner image. The image is processed and output as an image formed product (print or copy).

The electrophotographic apparatus of this example is cleanerless, and the photosensitive drum 1 after the toner image is transferred onto the transfer material P is transferred.
A dedicated cleaning device for removing a small amount of transfer residual toner remaining on the surface is not provided. The transfer residual toner on the surface of the photosensitive drum 1 after the transfer is carried to the developing portion c through the charging portion a and the exposing portion b as the photosensitive drum 1 continues to rotate, and is developed and cleaned by the developing device 3 (collected). ) (Cleanerless system).

In this embodiment, the developing sleeve 4b of the developing device 4 is rotated in the developing portion c in the direction opposite to the traveling direction of the surface of the photosensitive drum 1 as described above. It is advantageous for collecting the residual toner.

Since the transfer residual toner on the surface of the photosensitive drum 1 passes through the photosensitive portion b, the exposure process is performed on the transfer residual toner. However, since the amount of transfer residual toner is small, a great influence does not appear.

However, as described above, the transfer residual toner includes the one having a normal charge polarity, the one having a reverse charge polarity (reverse toner), and the one having a small charge amount. When a small amount of toner adheres to the charging roller 2 when passing through the charging section a, the charging roller undesirably contaminates the toner and causes charging failure.

Further, in order to effectively perform the development / cleaning of the transfer residual toner on the surface of the photosensitive drum 1 by the developing device 3, the charging polarity of the transfer residual toner on the photosensitive drum carried to the developing section c is set. It is necessary that the polarity is normal and that the amount of charge is the amount of charge of the toner that can develop the electrostatic latent image on the photosensitive drum by the developing device. Reversing toner and toner having an unsuitable charge amount cannot be removed / collected from the photosensitive drum by the developing device, resulting in a defective image.

With the diversification of user needs in recent years, a large amount of untransferred toner is generated at one time due to continuous printing operation of images with a high printing rate such as photographic images, and the above-mentioned problems occur. It further promotes it.

Therefore, in the present invention, the transfer residual toner (residual developer image) is made uniform in order to make the transfer residual toner on the photosensitive drum 1 uniform at the position downstream of the transfer portion d in the photosensitive drum rotation direction. Means 8 are provided, and at a position downstream of the transfer residual toner equalizing means 8 downstream of the photosensitive drum rotation and upstream of the charging portion a in the rotational direction of the photosensitive drum, the charge polarity of the transfer residual toner is a negative polarity that is a normal polarity. Toner (developer) charge amount control means 7 is provided for uniform alignment.

By providing the transfer residual toner equalizing means 8, the pattern transfer residual toner on the photosensitive drum 1 which is carried from the transfer portion d to the toner charge amount controlling means 7 has a large toner amount even if the toner amount is large. Is dispersed and stabilized on the surface of the photosensitive drum 1 and is not patterned, so that the toner is not concentrated on a part of the toner charge amount control means 7 and the entire transfer residual toner by the toner charge amount control means 7 is eliminated. The normal polarity charging process is always sufficiently performed, and the transfer residual toner is effectively prevented from adhering to the charging roller 2. Generation of a ghost image of the transfer residual toner image pattern is actually prevented.

In this embodiment, the transfer residual toner equalizing means 8 and the toner charge amount control means 7 are brush-like members having appropriate conductivity, and the brush portion is brought into contact with the surface of the photosensitive drum 1. It is provided. Reference numeral f is a contact portion between the transfer residual toner equalizing means 8 and the surface of the photosensitive drum 1. Reference numeral e is a contact portion between the toner charge amount control means 7 and the surface of the photosensitive drum 1.

In FIG. 3, the residual transfer toner uniformizing means 8 is grounded, but a power source may be arranged so that a positive voltage can be applied up to a range of + 500V.
If it exceeds + 500V, a ghost image may occur. It is considered that excess charges exert different influences on the solid image portion and the non-solid image portion on the first rotation of the photoconductor, which appears as a density difference on the second rotation of the photoconductor. A negative voltage is applied to the toner charge amount control means 7 from the power source S4.

The transfer residual toner remaining on the photosensitive drum 1 after the toner image is transferred onto the transfer material P at the transfer portion d is
The subsequent rotation of the photosensitive drum 1 reaches the contact portion f between the transfer residual toner equalizing means 8 and the photosensitive drum 1, and the transfer residual toner uniformizing means 8 temporarily sucks the toner. Here, since the amount of toner that the transfer residual toner equalizing means 8 can hold is limited, the toner is gradually released after reaching the saturated state and the photosensitive drum 1 is reached.
The toner adheres to the surface and is conveyed, but the toner adhesion state on the surface of the photosensitive drum 1, that is, the distribution of the toner adhered to the surface of the photosensitive drum 1 is made uniform.

The transfer residual toner on the surface of the photosensitive drum, which is uniformized by the transfer residual toner uniformizing means 8, reaches the contact portion e between the toner charge amount control means 7 and the photosensitive drum 1 by the subsequent rotation of the photosensitive drum 1. The transfer residual toner on the photosensitive drum 1 passing through the toner charge amount control means 7 is made to have a negative charge polarity, which is a normal polarity.

By aligning the charge polarity of the transfer residual toner to the negative polarity which is the normal polarity, when the charging portion a located further downstream is charged on the surface of the photosensitive drum 1 from above the transfer residual toner, The reflection force on the photosensitive drum 1 is increased, and the transfer residual toner is prevented from adhering to the charging roller 2.

Therefore, the amount of charge required for the transfer residual toner needs to be 2.2 times or more as compared with the amount of charge of the toner at the time of development.

FIG. 5 shows the relationship between the voltage applied to the toner charge amount control means 7 and the toner charge amount after passing through the toner charge amount control means 7. When no voltage is applied to the toner charge amount control means 7, as described above, the transfer residual toner is affected by the negative polarity toner in the image area, the positive polarity toner in the non-image area, and the positive polarity voltage of the transfer. Since the toner includes the toner whose polarity is reversed to the positive polarity, the charge amount is indefinite. Further, it can be seen that by applying a voltage to the toner charge amount control means 7, the toner charge amount after passing through the toner charge amount control means 7 is increased and is saturated at a certain value or more.

Next, a graph showing the relationship between the transfer residual toner charge amount and the adhesion amount to the charging roller 2 when the transfer residual toner amount is 1 before the transfer residual toner enters the charging portion a is shown in FIG. 6 shows. It can be seen that the adhesion amount is reduced by increasing the charge amount of the transfer residual toner. Further, at this time, the occurrence of a charging failure image due to the transfer residual toner adhering to the charging roller 2 occurred when the transfer residual toner charge amount was −55 μC / g or less.

Therefore, in order to prevent the transfer residual toner from adhering to the charging roller 2 and suppress the occurrence of a poorly charged image, the charge amount of the transfer residual toner is compared with the toner charge amount at the time of development. It turns out that it is necessary to double or more.

Next, the recovery of the transfer residual toner in the developing step will be described.

As described above, the developing device 4 is of a cleanerless type in which the transfer residual toner is cleaned simultaneously with the development.
Table 1 shows the relationship with the amount of charge for the residual toner to be collected by the developing device 4.

[0082]

[Table 1]

The toner charge amount for the transfer residual toner on the photosensitive drum 1 to be collected by the developing device 4 is 0.5 to 1.8 as compared with the toner charge amount at the time of development (-25 μC / g).
It needs to be doubled.

However, in order to prevent the toner from adhering to the charging roller 2 as described above, the transfer residual toner which is negatively charged to a large negative polarity of −70 μC / g by the toner charge amount control means 7 is used in the developing device 4. In order to recover, it is necessary to remove the charge.

FIG. 7 shows the relationship between the toner charge amount after the toner on the photosensitive drum having a charge amount of −70 μC / g after passing through the charge roller 2 and Vpp of the AC voltage applied to the charge roller 2. Show. It can be seen that power is being received as Vpp of the AC voltage is increased.

By applying an AC voltage to the charging roller 2 in order to charge the peripheral surface of the photosensitive drum 1, the transfer residual toner is AC discharged. In the developing process, the untransferred toner on the photosensitive drum 1 where the toner should not be developed is collected by the developing device 4 for the above reason.

Thus, the transfer residual toner is transferred from the transfer portion d to the charging portion a by aligning the tribo of the transfer residual toner on the photosensitive drum 1 with the negative polarity which is the normal polarity by the toner charge amount control means 7 and performing the charging processing. While preventing the toner from adhering to the charging roller 2, the charging roller 2 charges the photosensitive drum 1 to a predetermined potential, and at the same time, the toner charging amount control means 7 transfers the toner to a negative polarity which is a normal polarity. By controlling the charge amount of the residual toner to an appropriate charge amount capable of developing the electrostatic latent image on the photosensitive drum by the developing device 4, the transfer residual toner can be efficiently collected by the developing device. In addition, it is possible to provide an electrophotographic apparatus that does not have a charging failure or a defective image and that has the advantages of the cleanerless system.

[0088]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In addition, "part" in an Example means a "mass part."

Regarding the surface roughness referred to in the present invention, according to JIS B 0601 (1994), the surface roughness meter Surfcoder SE3500 of Kosaka Laboratory was used, and the cutoff was 0.8 mm and the measurement length was 8 mm. I went there.

The arithmetic mean roughness Ra and the ten-point mean roughness R
z, the average spacing Sm of the irregularities is JIS B 0601 (199
The maximum height Rmax is R.
Indicates maxD, that is, RmaxDIN.

(Example 1) A6 obtained by hot extrusion
An aluminum tube having an outer diameter of 063, an inner diameter of 30.5 mm, an inner diameter of 28.5 mm, a length of 260.5 mm, a runout accuracy of 100 μm, and a surface ten-point average roughness Rz of 10 μm was prepared.

This blank tube was mounted on a lathe and cut with a diamond sintering tool so as to have an outer diameter of 30.0 ± 0.02 mm, a runout accuracy of 15 μm, and a surface ten-point average roughness Rz = 0.2 μm. processed. Spindle speed at this time is 3000r
The feed rate of pm and the cutting tool was 0.3 mm / rev, and the processing time was 24 seconds excluding attachment and detachment of the work.

The obtained aluminum cutting tube was subjected to liquid honing treatment under the following conditions using the liquid (wet) honing device (manufactured by Fuji Seiki Seisakusho) shown in FIG.

<Liquid Honing Conditions> Abrasive grains = Spherical alumina beads Average particle size 30 μm
(Product name: CB-A30S manufactured by Showa Denko KK) Suspension medium = water abrasive / suspension medium = 1/9 (volume ratio) Rotational speed of aluminum cutting tube = 1.67 s ⁻¹ Air blowing pressure = 0. 15 MPa Gun moving speed = 13.3 mm / sec Distance between gun nozzle and aluminum tube = 200 mm Honing abrasive grain discharge angle = 45 ° Polishing liquid projection frequency = 1 time (one way)

The cylinder surface roughness after honing is the maximum height (Rmax) = 2.2 μm and the ten-point average roughness (Rmax).
z) = 1.4 μm, arithmetic average roughness (Ra) = 0.20 μ
m, the average spacing of irregularities (Sm) = 37 μm.

Next, a solution prepared by dissolving 5 parts of the polyamide copolymer in a mixed solvent of 70 parts of methanol / 25 parts of butanol was applied by dip coating and dried to form an undercoat layer having a film thickness of 1 μm.

Next, 3.5 parts of hydroxygallium phthalocyanine crystals having strong peaks at Bragg angles (2θ ± 0.2 °) of 7.4 ° and 28.2 ° in CuKα characteristic X-ray diffraction and polyvinyl butyral resin ( (Product name: S-REC BH-S, manufactured by Sekisui Chemical Co., Ltd.) 1 part was added to 120 parts of cyclohexanone and dispersed for 3 hours in a sand mill using 1 mmφ glass beads, and 120 parts of methyl ethyl ketone was added to dilute it to generate a charge. A layer coating was prepared. This charge generation layer coating material is dip-coated on the undercoat layer and dried at 100 ° C. for 10 minutes to give a film thickness of 0.15 μm.
The charge generation layer of was formed.

Next, as a charge transport material, 10 parts of a compound represented by the following formula:

[0099]

[Chemical 1] Polycarbonate resin (Product name: Panlite L-125
0, Teijin Kasei) was dissolved in a mixed solvent of 50 parts of monochlorobenzene / 10 parts of dichloromethane. This paint is applied on the charge generation layer described above by a dipping method, and the temperature is 110 ° C.
And dried for 1 hour to form a charge transport layer having a film thickness of 21 μm.

The electrophotographic photosensitive member thus prepared was mounted in an electrophotographic apparatus using the above-mentioned cleanerless image forming method, and the temperature and humidity were low (15 ° C./10% RH) and normal temperature and humidity (2
3 ℃ / 60% RH) and high temperature and high humidity (32.5 ℃ / 85%)
The paper passing durability evaluation of 5000 sheets was continuously performed under the environment of (RH). A voltage of +400 V was applied to the transfer residual toner uniformizing means. Table 2 shows the results of potential measurement at the initial stage and after the endurance of 5,000 sheets.

Further, in these environments, images were produced by the above apparatus as follows. From the start of printing the print image, a square solid black portion of 25 mm square was arranged at the portion where the photosensitive member was rotated once, and a halftone test chart was printed in which one dot was printed in the Keima pattern after the second rotation of the photosensitive member. That is, the ghost of the solid black portion can be evaluated in the halftone portion. The results are shown in Table 3.

(Example 2) In the electrophotographic apparatus,
Image evaluation was performed in the same manner as in Example 1 except that the transfer residual toner equalizing means was grounded. The electrophotographic photoreceptor used in Example 1. The results are shown in Tables 2 and 3.

(Embodiment 3) In the electrophotographic apparatus,
Image evaluation was performed in the same manner as in Example 1 except that a voltage of +500 V was applied to the transfer residual toner uniformizing means. The electrophotographic photoreceptor used in Example 1. The results are shown in Tables 2 and 3.

Example 4 The thickness of the charge transport layer is 22 μm.
An electrophotographic photosensitive member was prepared and image evaluation was performed in the same manner as in Example 1 except that the above was used. The results are shown in Tables 2 and 3.

Comparative Example 1 An electrophotographic photosensitive member was prepared and image evaluation was carried out in the same manner as in Example 1 except that the aluminum cutting tube was not subjected to honing treatment. The results are shown in Tables 2 and 3.

(Comparative Example 2) 50 parts of titanium oxide powder coated with tin oxide containing 10% antimony oxide, 25 parts of resol type phenol resin, instead of performing liquid honing treatment on an aluminum cutting tube, 20 parts of methyl cellosolve, 5 parts of methanol and 0.002 parts of silicone oil (polydimethylsiloxane / polyoxyalkylene copolymer, average molecular weight 3000) are dispersed for 2 hours in a sand mill using 1 mmφ glass beads to prepare a coating for a conductive layer. Prepared, aluminum cylinder (φ30m
m), the conductive layer coating material is applied by dip coating, and at 140 ° C., 30
After drying for a minute, a conductive layer having a film thickness of 20 μm was formed. An electrophotographic photosensitive member was prepared and image evaluation was performed in the same manner as in Example 1 except for the above. The results are shown in Tables 2 and 3.

(Comparative Example 3) In the electrophotographic apparatus,
The same electrophotographic photosensitive member as that of Example 1 was used without carrying a residual developer image uniformizing means, and 5000 sheets were subjected to paper passing durability, and image evaluation was performed. The results are shown in Tables 2 and 3.

(Comparative Example 4) In the electrophotographic apparatus,
An electrophotographic photosensitive member similar to that of Example 1 was used to carry out 5000 sheet passing durability without mounting a developer charge amount control means,
Image evaluation was performed. The results are shown in Tables 2 and 3.

[0109]

[Table 2]

[0110]

[Table 3]

<Others> 1) The transfer residual toner uniformizing means 8 and the toner charge amount controlling means 7 are fixed brush-like members in the embodiment, but may be arbitrary brush rotating bodies, elastic roller bodies, sheet-like members, or the like. Can be a member of the form

2) The image bearing member has a surface resistance of 10 ⁹ to 10 ¹⁴
It may be a direct injection type having a charge injection layer of Ω · cm. Similar effects can be obtained even when the charge injection layer is not used, for example, when the charge transport layer has the above resistance range. An amorphous silicon photoreceptor having a surface layer having a volume resistance of about 10 ¹³ Ω · cm may be used.

3) As the flexible contact charging member, in addition to the charging roller, a fur brush, felt, cloth or the like having a shape and material can be used. Further, more appropriate elasticity, conductivity, surface property, and durability can be obtained by combining various materials.

4) As the waveform of the alternating voltage component (AC component, voltage whose voltage value changes periodically) of the oscillating electric field applied to the contact charging member or the developing member, a sine wave, a rectangular wave, a triangular wave, or the like is used as appropriate. It is possible. Turn on the DC power supply periodically /
It may be a rectangular wave formed by turning off.

5) The exposure means as the information writing means for the charged surface of the photoconductor as the image carrier is not limited to the laser scanning means of the embodiment, but is, for example, digital exposure means using a solid light emitting element array such as an LED. May be
It may be an analog image exposure means using a halogen lamp, a fluorescent lamp or the like as a document illumination light source. In short, what is necessary is just to form an electrostatic latent image corresponding to image information.

6) The image carrier may be an electrostatic recording dielectric or the like. In this case, the dielectric surface is uniformly charged, and then the charged surface is selectively neutralized by a neutralizing means such as a static elimination needle head or an electron gun to write and form an electrostatic latent image corresponding to target image information. .

7) The toner developing system / means for the electrostatic latent image is
It is optional. The reversal development method or the regular development method may be used.

Generally, in the method of developing an electrostatic latent image, a non-magnetic toner is coated on a developer carrying member such as a sleeve with a blade or the like, and a magnetic toner is coated on a developer carrying member. A method for developing an electrostatic latent image by applying it to the image carrier in a non-contact state by coating with a magnetic force and developing the electrostatic latent image on the developer carrying member as described above. A method in which a coated toner is applied to an image carrier in a contact state to develop an electrostatic latent image (one-component contact development) and a method in which a magnetic carrier is mixed with toner particles is used as a developer (two-component development). Used as a developer) to be conveyed by magnetic force and applied to the image carrier in a contact state to develop an electrostatic latent image (two-component contact development), and the above two-component developer to the image carrier. Applied in a non-contact state It is roughly divided into four types of methods (2-component non-contact development) for developing the latent image.

8) The transfer means is not limited to the roller transfer of the embodiment, but may be blade transfer, belt transfer, other contact transfer charging system, or non-contact transfer charging system using a corona charger. .

9) The present invention can be applied not only to monochromatic image formation using an intermediate transfer member such as a transfer drum or transfer belt, but also to an electrophotographic apparatus for forming multicolor or full-color images by multiple transfer or the like.

[0121]

As described above, according to the present invention, in the cleanerless type electrophotographic apparatus which removes and collects the transfer residual developer on the image carrier after the transfer step by the development / cleaning and reuses it. It is possible to provide an electrophotographic apparatus and a process cartridge which have good electrophotographic characteristics in which an image defect such as a ghost does not occur in any environment and a potential change is small even when repeatedly used.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a liquid honing treatment apparatus according to the present invention.

FIG. 2 is an enlarged configuration diagram in the vicinity of a substrate of the liquid honing treatment apparatus used in the present invention.

FIG. 3 is a schematic diagram showing a schematic configuration of an electrophotographic apparatus of the present invention.

FIG. 4 is a schematic view showing a layer structure of an electrophotographic photosensitive member and a charging roller.

FIG. 5 is a relationship diagram of a voltage applied to a toner charge amount control unit and a charge amount of transfer residual toner.

FIG. 6 is a relationship diagram of a charge amount of transfer residual toner and a toner adhesion amount to a charging roller.

FIG. 7 is a relationship diagram between the toner charge amount after passing through the charging roller and Vpp of the applied AC voltage.

[Explanation of symbols]

1 Electrophotographic photoconductor (photoconductor drum) 2 charging roller 3 Exposure means (laser beam scanner) 4 Developing device 5 Transfer roller 6 fixing device 7 Toner charge amount control means (developer charge amount control means) 8 Transfer residual toner uniformizing means (residual developer uniformizing means) S1 to S4 Bias voltage application power supply 21 nozzles 22 Air supply pipe 23 Honing liquid circulation pipe 24 work (cylindrical substrate) 25 Work stand 26 Work rotation motor 27 Honing liquid 28 Stirring motor 29 Propeller for stirring 30 Honing liquid recovery tube 31 Honing liquid circulation pump 32 nozzle movement direction 33 Honing Abrasive

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/08 507 G03G 15/08 507B (72) Inventor Kumon Kuofumi 3-30 Shimomaruko, Ota-ku, Tokyo No. 2 Canon Inc. (72) Inventor Haruyuki Tsuji 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiroshi Saito 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon In-house F-term (reference) 2H035 CB02 CB03 2H068 AA52 CA32 EA05 2H077 AA11 AA37 AB06 AC12 AC16 AD13 AD36 BA07 DA10 DA42 DA62 EA03 EA15 2H134 GA01 GB02 HF13 MA02 MA11 2H200 FA18 GA23 GA34 GA45 GA25 GB07 B37 HA12 GB03 GA12 GA57 GA59 GA59 HB22 HB45 HB48 JA02 JA28 JB10 JB32 MA03 MA04 NA02 NA03

Claims (7)

[Claims] 1. An electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member, information writing means for forming an electrostatic latent image on the electrophotographic photosensitive member that has been subjected to charging processing, and a developer for the electrostatic latent image. And a transfer means for transferring the visualized developer image to a transfer material and a charging means for charging the developer on the surface of the electrophotographic photosensitive member. And a developer charge amount control means that is located upstream of the developer charge amount control means and downstream of the transfer means, and remains on the surface of the electrophotographic photosensitive member after the developer image is transferred to the transfer material. A residual developer image uniformizing means for uniformizing the residual developer image, and the residual developer image remaining on the electrophotographic photosensitive member after the transfer of the developer image is uniformized by the residual developer image uniformizing means. Of the residual developer on the electrophotographic photosensitive member, In an electrophotographic apparatus, in which an electrophotographic apparatus is charged to a normal polarity by a charge control means and the surface of the electrophotographic photoreceptor is charged by the charging means, and at the same time, an aluminum substrate of the electrophotographic photoreceptor contains an abrasive liquid in an electrophotographic apparatus. An electrophotographic apparatus characterized by being polished by using. 2. The electrophotographic apparatus according to claim 1, wherein the charging unit is a contact charging type. 3. The electrophotographic apparatus according to claim 1, wherein an oscillating electric field is applied to the charging means. 4. The electrophotographic apparatus according to claim 1, wherein the information writing unit is an exposure unit. 5. The electrophotographic apparatus according to claim 1, wherein the residual developer image uniformizing means comprises an electrode portion having a potential difference with respect to the electrophotographic photosensitive member. 6. The electrophotographic apparatus according to claim 1, wherein an applied voltage of the residual developer image uniformizing means is within a range of 0V to + 500V. 7. The electrophotographic photosensitive member of the electrophotographic apparatus according to claim 1 is integrated with at least one unit selected from the group consisting of a charging unit, an auxiliary charging unit and a developing unit. A process cartridge which is supported and is detachable from the main body of the electrophotographic apparatus.