JP2009069342A - Image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method capable of performing stable charging operation, at all times, and to provide an image forming method, capable of improving the photoreceptor cleaning performance and forming high quality images. <P>SOLUTION: The photoreceptor 101 is equipped with a photoconductive layer, made of a non-monocrystal line material containing silicon atoms as the matrix. The cleaning auxiliary member 109b, having a conductive elastic roller, is disposed on the upper stream side in the rotational direction of the photoreceptor than the touch point of the cleaning blade 109a of the photoreceptor and moreover, on the lower stream side of the transfer member 105. The conductive elastic roller touches the photoreceptor with inorganic conductive particulates and inorganic grinding particulates whose shape is rectangular therebetween and rotates, having a peripheral speed difference between the conductive elastic roller and the photoreceptor. A direct current bias is applied to the conductive elastic roller, and the volume resistivity of the inorganic conductive particulate is in the range of 1×10<SP>4</SP>Ωcm to 1×10<SP>8</SP>Ωcm, and the resistance of the conductive elastic roller is in the range of 1×10<SP>4</SP>Ω to 1×10<SP>8</SP>Ω. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  In the present invention, a toner image is formed on the surface of an image carrier such as an electrophotographic photosensitive member or an electrostatic recording dielectric, the formed toner image is transferred to a recording medium, and the image carrier after transfer is repeatedly formed into an image. The present invention relates to an image forming method to be used.

In the electrophotographic image forming method, an electrophotographic photosensitive member using a photoconductive substance is used as an image carrier. After the photoreceptor is uniformly charged to a required polarity and potential, an exposure corresponding to the image pattern is performed to form an electrical latent image, and the latent image is visualized as a toner image. Generally, the visualized toner image is transferred to a recording medium such as paper, and the transferred toner image is fixed to the recording medium to form an image formed product. The photoreceptor is repeatedly used for image formation. In the above, the toner image formed on the photoconductor is primarily transferred to an intermediate recording medium such as an intermediate transfer drum or belt, and the toner image primarily transferred onto the intermediate recording medium is secondarily transferred to a recording medium such as paper. There is also a system in which an image formed product is obtained by fixing a secondary transfer toner image on a recording medium.
In the electrostatic recording image forming method, an electrostatic recording dielectric using a dielectric substance is used as the image carrier. After the electrostatic recording dielectric is uniformly charged to a required polarity and potential, an electric latent image is formed by performing charge removal corresponding to the image pattern. Thereafter, as in the case of the above-described electrophotographic image forming method, an image formed product is obtained by a development / transfer / fixing process or by a development / primary transfer / secondary transfer / fixing process. The electrostatic recording dielectric is repeatedly used for image formation.
In recent years, image forming apparatuses such as electrophotographic apparatuses and electrostatic recording apparatuses using the image forming method as described above have all output terminals such as copiers, printers, and facsimiles. Widely accepted in the market.

One of the performances required for such an image forming apparatus as a network-compatible output terminal is the duty cycle of the apparatus main body.
The duty cycle is a limit number of sheets in which the apparatus main body continues to operate normally without requiring maintenance by an operator.
One of the greatest dominating factors of the duty cycle is the life of the image carrier that is used repeatedly. If the life of the image carrier can be extended, it is possible to reduce waste, that is, reduce consumables, extend the life of consumables, and improve reliability. From the viewpoint of environmental protection, development of such a technology is required.
Under such circumstances, as an image carrier in an image forming apparatus of an electrophotographic system, an abrasion-resistant photoconductor such as an amorphous silicon (a-Si) photoconductor or an organic photoconductor having a protective layer on the outermost layer has been gradually used. ing. Such a highly durable photoconductor has become indispensable particularly in a high-speed machine that requires high reliability (see Patent Document 1).
On the other hand, conventionally, a corona discharge method has been used as a means for charging an image bearing member such as a photosensitive member / dielectric member and other charged members (including a charge removing treatment). In this method, a high voltage of several KV is applied to a discharge wire to cause discharge between charged members such as a photosensitive member to charge the surface of the charged member to a desired potential. However, this corona discharge method has drawbacks such as the generation of undesirable discharge products such as ozone with discharge.
Therefore, recently, a so-called contact charging method in which a conductive charging member is brought into contact with a member to be charged such as a photosensitive member and a voltage is applied between the charging member and the member to be charged to charge the member to be charged to a desired potential. System (or direct charging) devices have come to be used. This contact charging method has advantages such as less generation of ozone and a smaller applied voltage than the corona discharge method.
In the contact charging method, the charging member is not necessarily in contact with the member to be charged. As long as a dischargeable region determined by the gap voltage and the correction Paschen curve is secured between the charging member and the member to be charged, non-contact (proximity) may be used.

The voltage applied between the charging member and the member to be charged may be only a DC voltage (DC application method). An oscillating voltage (a voltage whose voltage value periodically changes with time), in particular, an oscillating voltage having a peak-to-peak voltage more than twice the charging start voltage of the charged body when a DC voltage is applied, is applied to the charging member. The charging method (AC application method) is effective because it can perform uniform charging (static elimination) processing. (See Patent Document 2)
When the above voltage is applied, the resistance value of the high resistance coating layer and conductive elastic layer of the charging roller as the charging member tends to increase with time, and this is promoted as the amount of current increases, which is also stable. This is a factor that deteriorates the uniform charging performance.
Furthermore, the contact portion between the charging roller and the photosensitive drum tends to become unstable with respect to the photosensitive drum rotating at a high speed, and thus uneven charging tends to occur. These are also true for the charging member having a form / shape other than that of a roller.
Therefore, such a charging device of the contact charging method is used as a charging processing device for an image carrier or the like in a high-class image forming apparatus such as a high-speed copying machine having a high copy volume and requiring high reliability. It was difficult. To solve this problem, a technique has been proposed in which a plurality of charging members are arranged to stabilize the charging performance (see Patent Document 3, Patent Document 4, and Patent Document 5).
JP-A-60-67951 JP-A 63-149669 JP-A-7-110616 Japanese Patent Application Laid-Open No. 2004-37894 JP 2006-162961 A

However, in the method of arranging a plurality of photosensitive member contact charging members side by side, not only the problem regarding the installation space of the charging member itself, but also the photosensitive member needs to be enlarged in diameter, which tends to increase the size of the apparatus.
Further, as a problem in the contact charging of the amorphous silicon photoconductor, the slipperiness of the surface of the photoconductor tends to be lower than that of corona charging. As a result, when the elastic blade is brought into contact with the transfer residual toner, it is necessary to improve the cleaning performance. Furthermore, as a problem of the contact charging system, the latent image is blurred due to low resistance due to the discharge product adhering to the surface of the photoreceptor, particularly during image formation in a high humidity environment. There is a problem that easily occurs. In contact charging, since the amount of discharge products is small, the phenomenon that the discharge products adhere to and accumulate on the surface of the photoconductor due to the device being left after image formation is unlikely to occur. However, in contact charging, the above phenomenon may occur even if the amount of discharge products generated by discharging near the surface of the photoreceptor is small. Among contact charging methods, the photosensitive member charging method using injection charging is not charged mainly by the discharge phenomenon, so that it is difficult for the discharge to occur, but the performance of the photosensitive member surface during paper passing may still be deteriorated.
The same can be said for the auxiliary charging means when the auxiliary charging means for assisting charging is provided in the high-speed image forming apparatus. For this reason, it is difficult for the surface of the photoreceptor to be deteriorated during image formation due to discharge even in the auxiliary charging step, and a mechanism capable of performing better cleaning is required.
The present invention includes an auxiliary means for assisting the contact charging method in the above-described image forming method, an image forming method capable of always performing a stable charging process, and a high quality by improving the cleaning performance of the photoreceptor. An object of the present invention is to provide an image forming method capable of forming a correct image.

The above object can be achieved by the following configuration of the present invention.
A charging step for charging the surface of the photosensitive member with a contact charging device, a latent image forming step for forming an electrostatic latent image on the charged photosensitive member by exposure, and a developing device for developing the electrostatic latent image formed on the photosensitive member A developing process for forming a toner image by developing the toner contained in the toner, a transfer process for transferring the toner image on the photoconductor to a transfer material by a transfer member, and a cleaning device for the transfer residual toner on the photoconductor An image forming method including a cleaning step of removing with a cleaning blade in contact with the photoconductor,
The photoconductor is a photoconductor having a photoconductive layer composed of a non-single crystal material based on silicon atoms,
A cleaning auxiliary member having a conductive elastic roller is disposed on the upstream side of the photosensitive member rotation direction and on the downstream side of the transfer member from the contact point of the cleaning blade of the photosensitive member.
The conductive elastic roller is a roller that comes into contact with the photosensitive member through inorganic conductive fine particles and inorganic abrasive fine particles having a rectangular parallelepiped shape and rotates with a circumferential speed difference from the photosensitive member,
A DC bias is applied to the conductive elastic roller,
The volume resistivity of the inorganic conductive fine particles is 1 × 10 ⁴ Ω · cm or more and 1 × 10 ⁸ Ω · cm or less,
A resistance value of the conductive elastic roller is 1 × 10 ⁴ Ω or more and 1 × 10 ⁸ Ω or less.

  According to a preferred aspect of the present invention, in addition to charging in the primary charging step, the amorphous silicon photoconductor is contacted while saving space by allowing the cleaning auxiliary member to function as an auxiliary charging device and performing auxiliary charging. It is possible to stabilize the charging. Furthermore, the cleaning performance is dramatically improved while preventing image flow during paper passing due to discharge in the auxiliary charging step and the primary charging step, and as a result, high-quality image output can be performed over a long period of time.

<Image forming method>
The image forming method of the present invention comprises a charging step of charging the surface of a photoconductor with a contact charging device, a latent image forming step of forming an electrostatic latent image on the charged photoconductor by exposure, and an image formed on the photoconductor. Developing the electrostatic latent image using toner contained in a developing device to form a toner image, transferring the toner image on the photoconductor to a transfer material by a transfer member, and the photoconductor An image forming method including a cleaning step of removing the above transfer residual toner by a cleaning blade in contact with the photoconductor in a cleaning device, wherein the photoconductor is made of a non-single crystal material having a silicon atom as a base material. A photosensitive member having a photoconductive layer formed thereon, and a cleaning auxiliary member having a conductive elastic roller is located on the upstream side of the photosensitive member rotating direction from the contact point of the cleaning blade of the photosensitive member and is transferred The conductive elastic roller disposed on the downstream side of the material contacts the photoconductor via inorganic conductive fine particles and inorganic abrasive fine particles having a rectangular parallelepiped shape, and rotates with a difference in peripheral speed from the photoconductor. A direct current bias is applied to the conductive elastic roller, and the volume resistivity of the inorganic conductive fine particles is 1 × 10 ⁴ Ω · cm or more and 1 × 10 ⁸ Ω · cm or less, The resistance value of the conductive elastic roller is 1 × 10 ⁴ Ω or more and 1 × 10 ⁸ Ω or less.

FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus using an image forming method according to the present invention. This image forming apparatus is a digital electrophotographic copying machine.
Reference numeral 101 denotes a drum-type electrophotographic photosensitive member (hereinafter also referred to as a drum) as an image carrier. The drum 101 is an amorphous silicon (a-Si) photosensitive member, and is driven to rotate at a predetermined speed in a clockwise direction indicated by an arrow by a drive mechanism unit (not shown) around a central shaft portion.
Reference numeral 102 denotes a primary charging device that uniformly primary charges the drum surface to a predetermined polarity and potential. The charging device 102 in this example is a discharge-type contact charging device using an elastic charging roller as a charging member, or a charge injection-type charging device using a magnetic brush roller.
In the present application, the charge injection method has the contact charging device downstream of the contact point of the cleaning blade with respect to the rotation direction of the photoreceptor, and the contact charging device is charged by rubbing inorganic conductive fine particles, which will be described later, with the photoreceptor. It is preferable that

The elastic charging roller of the discharge-type contact charging device is a charging roller having a basic configuration of a cored bar and a conductive elastic layer formed concentrically around the cored bar. Then, the drum is pressed against the drum with a predetermined pressing force against elasticity. A pressure contact portion between the drum 101 and the charging device 102 (hereinafter also referred to as a charging roller) is a charging portion of the drum. The charging roller 102 is rotated counterclockwise as indicated by an arrow following the rotation of the drum 101. A predetermined charging voltage is applied to the core of the charging roller from the power supply unit at a predetermined control timing. As a result, the rotating drum surface is uniformly contact-charged to a predetermined polarity and potential by the charging roller.

As shown in FIG. 2, the magnetic brush roller of the charge injection contact charging device includes a non-magnetic conductive charging sleeve 202b, a magnet roll 202c included therein, and charged magnetic particles 202a on the charging sleeve. The magnet roll 202c is fixed, and the charging sleeve 202b can be driven to rotate. The charged magnetic particles 202a are coated on the charging sleeve to a thickness of about 1 mm, a charging nip having a width of about 5 mm is formed between the drum 101 and the drum (photoconductor). A DC charging bias of −450 V is applied to the nonmagnetic conductive charging sleeve from a charging bias application power source, and the charging surface of the drum 101 is uniformly charged to approximately −450 V. In order to obtain uniform and stable charging performance, the rotational speed of the non-magnetic conductive charging sleeve in the rotating direction and the forward direction of the drum is not less than 2.0 times and not more than 3.0 times the linear velocity with respect to the drum (photoconductor). In the reverse direction, the linear velocity is preferably 1.1 times or more and 1.8 times or less.
Further, if the volume resistivity of these charged magnetic particles is too high, charges cannot be uniformly injected into the photoreceptor, and a fogged image due to minute charging failure tends to occur. On the other hand, if the surface is too low, when there is a pinhole on the surface of the photoreceptor, the current concentrates in the pinhole, the charging voltage drops, and the surface of the photoreceptor cannot be charged, and a charging failure like a charging nip tends to occur.

Examples of the charged magnetic particles of the magnetic brush that is the contact charging member include the following.
(1) A material obtained by kneading a resin and magnetic powder such as magnetite into a particle, or a material obtained by mixing conductive carbon or the like for resistance value adjustment.
(2) Sintered magnetite, ferrite, or those whose resistance value is adjusted by reducing or oxidizing them.
(3) The above-mentioned charged magnetic particles are coated with a resistance-adjusted coating material (such as a phenol resin in which carbon is dispersed) or plated with a metal such as Ni to adjust the volume resistivity to an appropriate value.

Reference numeral 103 denotes a laser scanner (exposure means) as image information writing means, which includes laser light emitting means for emitting light modulated in accordance with time-series electric digital pixel signals of image information inputted from the image processing unit, a rotating polygon mirror, and the like. It is configured. The image processing unit performs predetermined processing on electrical image information input from a document image photoelectric reading device (not shown) or an external host device (personal computer, facsimile, etc.) and outputs the processed information to the laser scanner 103. The laser scanner 103 scans and exposes the uniformly charged surface of the rotating drum 101 with modulated laser light at the exposed portion. As a result, the charge on the laser beam irradiated portion of the drum surface is removed, and an electrostatic latent image corresponding to the scanned and exposed image pattern is formed on the drum surface.

A developing device 104 develops the electrostatic latent image formed on the drum surface as a toner image. The developing device 104 in this example is a developing device using a non-magnetic one-component toner as a developer. Reference numeral 104a denotes a developing roller for non-magnetic toner as a developing member disposed in the developing container, and reference numeral 104b denotes a developer layer thickness regulating blade disposed with the edge portion in contact with the developing roller. A developer stirring and conveying screw shaft 104c is arranged in the developing container so as to be arranged substantially in parallel with the developing roller 104a. In the developing container, non-magnetic one-component toner is accommodated as a developer.
In addition, inorganic conductive fine particles, inorganic abrasive fine particles and the like are externally added to the nonmagnetic one-component toner at a predetermined ratio.
The developing roller 104a is arranged substantially parallel to the drum 101, and is opposed to the drum 101 with a predetermined slight gap. The developing roller 104a is rotationally driven at a predetermined speed in a counterclockwise direction indicated by an arrow by a driving mechanism (not shown). The non-magnetic one-component toner in the developing container is agitated while being cyclically conveyed in the developing container along the length of the screw shaft and frictionally charged to a predetermined polarity by the developer stirring and conveying screw shaft 104c being rotationally driven. The A part of the toner is adsorbed and carried on the outer surface of the developing roller 104a, conveyed along with the rotation of the developing roller 104a, and the layer thickness is regulated to a predetermined level by the developer layer thickness regulating blade 104b. Then, it is conveyed by the subsequent rotation of the developing roller 104a, and flies to the drum surface by the developing bias applied to the developing roller 104a and the electric field due to the surface potential of the drum 101 at the opposite portion between the drum 101 and the developing roller 104a. Thereby, the electrostatic latent image on the drum surface is developed as a toner image. The toner image formed on the drum surface includes inorganic conductive fine particles and inorganic abrasive fine particles that are externally added to the toner.

There are two methods for developing an electrostatic latent image: a regular development method and a reversal development method. The regular development method is a method in which a charged drum surface is exposed corresponding to a background portion of image information (background exposure method), and a portion other than the background portion is developed.
On the other hand, in the reverse development method, on the contrary, exposure is performed corresponding to the image information portion (image exposure method), and the non-exposed portion is developed. It is used by taking advantage of each feature. In the present invention, either development method may be used.

A transfer device 105 transfers the toner image formed on the drum surface to a recording material (transfer material) such as paper as a recording medium. The transfer device 105 of this example is a contact transfer device using a transfer roller as a transfer member. The transfer roller is a conductive elastic roller having a basic configuration of a cored bar and a conductive elastic layer formed concentrically around the cored bar. The transfer roller is arranged substantially in parallel with the drum 101 to resist elasticity. The drum is pressed against the drum with a predetermined pressing force. The pressure contact area between the drum 101 and the transfer roller is the drum transfer area. This transfer roller rotates in the counterclockwise direction of the arrow following the rotation of the drum 101.
On the other hand, at a predetermined paper feed timing, a recording material as a recording medium is fed from a paper feed mechanism section (not shown) and sent to a pair of registration rollers. The registration roller pair conveys the recording material at a timing so that the leading end of the recording material reaches the transfer portion in a predetermined manner in accordance with the timing when the leading end of the toner image on the rotating drum 101 reaches the transfer portion. The recording material introduced into the transfer site is sandwiched between the drum 101 and the transfer roller and conveyed to the transfer site. The core of the transfer roller has a polarity opposite to the charging polarity of the toner from the power supply until the trailing edge of the recording material passes through the transfer site after the leading edge of the recording material reaches the transfer site. A transfer voltage having a predetermined potential is applied. As a result, the toner image on the drum surface side is electrostatically transferred sequentially to the surface of the recording material conveyed through the transfer portion.
The recording material may be an intermediate transfer member such as an intermediate transfer drum or an intermediate transfer belt. In this case, the toner image is transferred again from the intermediate transfer member to a secondary recording medium such as paper.

  Reference numeral 106 denotes a corona charger as a post-transfer charger (recording material separating charger). This charger applies a static elimination current that weakens the electrical attraction force with the drum surface to the back surface of the recording material that exits the transfer site and is in electrostatic contact with the drum surface at the post-transfer site next to the transfer site. Thus, the recording material is separated from the drum surface.

The recording material leaving the transfer portion and separated from the drum surface is conveyed to the fixing device 107. The fixing device 107 in this example is a heat fixing device having a basic configuration of a rotating heating roller (fixing roller) and a pressure contact roller. The recording material is introduced into a fixing nip portion which is a pressure contact portion of the roller pair, and is nipped and conveyed, whereby the unfixed toner image is fixed as a fixed image on the recording material surface by being heated and pressurized, and an image formed product As shown in FIG.
A neutralizing member 108 is further disposed on the upstream side of the conductive elastic roller in the rotational direction of the photosensitive member and on the downstream side of the transfer member. After the static eliminating member is neutralized by the neutralizing member, the same as the surface potential of the photosensitive member. It is preferable to apply a direct current bias of polarity to the conductive elastic roller to charge the surface of the photoreceptor.

Further, the drum surface after the toner image transfer to the recording material (after the recording material separation) is cleaned by the cleaning device 109 and repeatedly used for image formation.
The cleaning device 109 is means for recovering and removing post-transfer residues such as transfer residual toner and paper powder remaining on the drum surface after the toner image transfer. For example, the cleaning blade 109a having elasticity mainly made of polyurethane rubber is brought into contact with the rotation of the drum 101 by a counter, thereby scraping off post-transfer residues such as transfer residual toner and paper dust on the drum surface. Done.
Residue after transfer, such as toner and paper dust, scraped off by the cleaning blade 109a is conveyed to one end in the longitudinal direction of the rotary conveying member by a rotary conveying member such as a toner feed blade, brush roller, and screw. The Further, the toner is discharged and conveyed from the cleaning container to a waste toner box (not shown).

Reference numeral 109b denotes a conductive and elastic cleaning auxiliary member (sliding auxiliary member) that acts on the drum surface after the transfer process and before the cleaning process by the cleaning blade 109a. Scraping, recoating, and rubbing of the drum surface. In this example, the cleaning auxiliary member 109b is a conductive sponge roller made of foamed resin, and the surface of the photoreceptor can be charged by applying a bias thereto. This is disposed in the cleaning container at a location upstream of the contact point of the cleaning blade of the photoconductor with respect to the drum rotation direction and downstream of the transfer member.
A toner coat member 109c applies an appropriate amount of toner on the sponge roller.
Reference numeral 109d denotes a transfer residual toner conveying screw. The transfer residual toner overflowing from the sponge roller is sent to a transfer residual toner collection box (not shown) provided on the back side of the image forming apparatus main body by the transfer residual toner conveying screw 109d.
The cleaning auxiliary members 109b are in contact with the drum 101 and are arranged substantially in parallel. The toner, inorganic conductive fine particles, inorganic polishing fine particles and the like are adsorbed on the outer peripheral surface of the cleaning auxiliary member 109b to form and carry a particle rubbing layer. The cleaning auxiliary member 109b is rotationally driven at a predetermined speed in the direction of the arrow by a driving mechanism (not shown). As the cleaning auxiliary member 109b rotates, the particle rubbing layer also rotates together with the cleaning auxiliary member 109b in the direction of the arrow. At the drum contact portion of the particle rubbing layer, the rotation direction of the particle rubbing layer is rotating in the forward direction with a difference in peripheral speed with respect to the drum rotation direction, and the drum surface is better than the particle rubbing layer. The toner is rubbed and the toner and external additives are reapplied. In addition, a bias is applied to the cleaning auxiliary member 109b to charge the surface of the photoreceptor through the particle rubbing layer.
The transfer residual toner (including paper dust and the like) on the drum carried to the cleaning device 109 by the rotation of the drum 101 after the transfer process is partially transferred by the conductive elastic roller that rubs the drum surface. Reaches the edge of the cleaning blade 109a while being scraped off. The particle rubbing layer functions to uniformly re-apply the transfer residual toner scraped off from the drum surface and reach the cleaning blade 109a.
Further, the surface of the drum is rubbed and polished with the inorganic polishing fine particles contained in the particle rubbing layer, and the inorganic polishing fine particles are uniformly re-applied to the drum surface to reach the cleaning blade 109a. The drum surface is also rubbed by inorganic abrasive particles that have reached the contact point between the cleaning blade 109 a and the drum 101.
In the present invention, inorganic conductive fine particles and inorganic abrasive fine particles are more likely to adhere to the sponge roller. Further, since the toner base is easily scraped off by the toner coating member, the inorganic conductive fine particles and the inorganic abrasive fine particles are easily removed, so that the inorganic conductive fine particles and the inorganic abrasive fine particles in the toner are particularly easily coated on the conductive elastic roller. It has become. As a result, inorganic conductive fine particles and inorganic polishing fine particles are positively supplied to the cleaning blade.
As described above, the inorganic conductive fine particles and the inorganic abrasive fine particles are externally added to the developer contained in the developing device 104, and adhere to the drum surface together with the toner when developing the electrostatic latent image on the drum surface. To do. In the transfer process, the toner moves to the recording material. At that time, the inorganic conductive fine particles and the inorganic fine particles remaining together with the toner on the surface of the photosensitive member are carried to the cleaning device 109 to be replenished to the surface of the conductive elastic roller. The

As described above, the cleaning auxiliary device according to the present invention is also a charging device for the photosensitive member. This is a contact charging method in which a roller-type conductive elastic member is used, which is brought into contact with the photosensitive member and a voltage is applied to apply an electric field to the surface of the photosensitive member.
In the contact charging method, a conductive charging member (contact charging member / contact charger) such as a roller type (charging roller), a fur brush type, a magnetic brush type, or a blade type is applied to a charged object such as an image carrier. A predetermined charging bias is applied to the charging member to charge the surface of the member to be charged to a predetermined polarity and potential. Roller-type charging members are widely used as simple and inexpensive charging members. However, roller-type contact charging members are harder to secure a close contact with the photoconductor than brush types, and are disadvantageous for the injection charging mechanism. Therefore, a method of charging by a discharge charging mechanism is mainly used.
The discharge charging mechanism is a mechanism for charging the surface of a member to be charged by a discharge phenomenon that occurs in a minute gap between the contact charging member and the member to be charged. Since the discharge charging mechanism has a constant discharge threshold value for the contact charging member and the member to be charged, it is necessary to apply a voltage larger than the charging potential to the contact charging member. Moreover, although the amount of generation is much smaller than that of a corona charger, the generation of discharge products is unavoidable in principle, so that harmful effects due to active ions such as ozone are unavoidable. The voltage applied to the charging member may be only a DC voltage or a DC / AC component superimposed voltage.
The contact charging member is not particularly limited as long as it is a member that makes contact with a photosensitive member such as a roller, a brush, or a plate, and the roller charging member has a large area for charging. In particular, in the present invention, it is advantageous and preferable in terms of rubbing the photoreceptor and scraping off toner, inorganic conductive fine particles, inorganic abrasive fine particles and the like.

As described above, the contact charging member (cleaning auxiliary member) used in the present invention includes the flexible conductive elastic roller disposed in contact with the photosensitive member with a predetermined pressing force. It is important that the conductive elastic roller as the contact charging member functions as an electrode. In other words, it is necessary to obtain sufficient contact with the photoreceptor to be charged by providing elasticity, and at the same time to have a sufficiently low resistance to charge the moving photoreceptor. On the other hand, it is necessary to prevent voltage leakage when there is a low breakdown voltage defect portion such as a pinhole in the photoreceptor. When an electrophotographic photosensitive member is used as the member to be charged, the resistance value of the conductive elastic roller is 1 × 10 ⁴ Ω or more and 1 × 10 ⁸ Ω or less in order to obtain appropriate chargeability and leakage resistance. . The resistance value of the conductive elastic roller is preferably 5 × 10 ⁴ Ω or more and 5 × 10 ⁷ Ω or less, more preferably 1 × 10 ⁵ Ω or more and 1 × 10 ⁷ Ω or less.
The method for measuring the resistance value of the conductive elastic roller is as follows. First, a temperature of 23 ° C
An φ30 mm aluminum cylinder is prepared to be opposed to the conductive elastic roller in an environment with a humidity of 5% RH, and is brought into contact with the aluminum cylinder with a contact linear pressure of 15 mN / mm. Thereafter, while rotating the aluminum cylinder, a DC voltage of 300 V is applied to the conductive elastic roller mandrel, and the amount of current flowing through the aluminum cylinder at that time is measured to calculate the resistance value.
On the other hand, if the hardness of the conductive elastic roller is too low, the shape is not stable, and the contact property with the photosensitive member is deteriorated. If it is too high, a charging nip portion cannot be secured between the photosensitive member and the micro contact property to the surface of the photosensitive member is deteriorated. The hardness of the conductive elastic roller is preferably 20 degrees or more and 50 degrees or less, and particularly preferably 25 degrees or more and 40 degrees or less in international rubber hardness (IRHD).
The international rubber hardness is measured with a durometer hardness tester based on the method of Japanese Industrial Standard JISK6253.

  The material of the elastic layer of the conductive elastic roller is preferably an elastic foam, but is not limited thereto. Examples of the elastic layer material include EPDM, urethane, NBR, silicone rubber, IR, etc., a rubber material in which a conductive material such as carbon black or metal oxide is dispersed for resistance adjustment, and those obtained by foaming these materials. It is done. It is also possible to adjust the resistance using an ion conductive material without dispersing the conductive substance.

  The conductive elastic roller sets and applies a DC voltage value (DC bias) so that the photosensitive member has a desired potential. Preferably, an alternating voltage (alternating current bias) that is an energy for putting a charge on the surface of the photoreceptor is superimposed on the direct current bias. For example, when a potential of −200 V is applied to the photoreceptor surface, a −200 V DC voltage is applied. Further, although depending on the charging means and the resistance of the photosensitive member, it is further preferable to superimpose an AC bias of about 0.1 to 2.0 kV because the latent image memory is easily erased.

  When the contact linear pressure between the conductive elastic roller and the photosensitive member exceeds 100 mN / mm, the photosensitive member is easily scraped or toner is easily fused to the photosensitive member, and when the linear pressure is less than 10 mN / mm. Contact unevenness easily occurs and charging unevenness easily occurs. Therefore, the contact linear pressure is preferably 10 mN / mm or more and 100 mN / mm or less. More preferably, they are 20 mN / mm or more and 60 mN / mm or less, Especially preferably, they are 25 mN / mm or more and 40 mN / mm or less.

The rotation direction of the conductive elastic roller is preferably in the forward direction with respect to the rotation of the photoconductor from the viewpoint of the cleaning property of toner re-application to the photoconductor.
The speed difference ratio between the linear velocity of rotation of the conductive elastic roller and the linear velocity of rotation of the photosensitive member is preferably 1% or more and 80% or less, and preferably 5% or more and 50% or less. Is more preferably 8% or more and 30% or less.
When the speed difference ratio is less than 1%, the injection chargeability is greatly impaired, and when it exceeds 80%, the photoreceptor is easily damaged.
The speed difference ratio (%) can be obtained by the following formula (1).
Formula (1): Speed difference ratio (%) = {(Sr / Sd) −1} × 100
However,
Sr: Linear speed of rotation of conductive elastic roller (mm / sec)
Sd: photosensitive member rotation linear velocity (mm / sec)
It is.

  In the pressure contact injection charging using the conductive elastic roller and the inorganic conductive fine particles, the linear velocity of rotation of the photosensitive member is 250 mm / sec or more and 600 mm / sec or less from the viewpoint of injection charging stability of the charging nip portion. It is preferable. The linear velocity of rotation of the photoreceptor is more preferably 270 mm / sec or more and 450 mm / sec or less.

<Photoreceptor used in the present invention>
The photoreceptor used in the present invention is preferably a durable photoreceptor that is less worn by a contact member such as a cleaning blade. Accordingly, the photoconductor used in the present invention is a photoconductor having a photoconductive layer made of a non-single crystal material having a silicon atom as a base. In particular, amorphous silicon (a-Si) photoreceptors are very hard with a Vickers hardness of 500 or more (500 Kg / m ² or more, JIS standard), and are excellent in durability, heat resistance, and environmental stability. preferable.
FIG. 3 shows an example of the amorphous silicon (a-Si) photoreceptor.
The amorphous silicon (a-Si) photoreceptor used in the present invention is obtained by sequentially laminating a photoconductive layer 302 and a surface protective layer 303 on a substrate 301 made of a conductive material such as Al or stainless steel ( (See FIG. 3 (a)).
In addition to these layers, various functional layers such as a lower charge injection blocking layer 304, an upper charge injection blocking layer 305, a charge injection layer, and an antireflection layer can be provided as necessary. For example, by providing a lower charge injection blocking layer 304, an upper charge injection blocking layer 305, and the like, and selecting a group 13 element and a group 15 element in the periodic table as a dopant, the charging polarity such as positive charging and negative charging can be controlled. This is possible (see FIG. 3B).
The shape of the substrate used in the present invention may be as desired depending on the driving method of the photoreceptor. As the base material, it is common to use conductive materials such as Al and stainless steel. For example, these conductive materials are deposited on non-conductive materials such as various plastics and ceramics. In addition, those imparted with conductivity can also be used.
A typical example of the photoconductive layer 302 is an amorphous material containing silicon atoms and hydrogen atoms or halogen atoms (abbreviated as “a-Si (H, X)”). Further, the layer thickness of the photoconductive layer 302 is not particularly limited, but about 15 to 50 μm is appropriate in consideration of the manufacturing cost. Further, in order to improve the characteristics, a plurality of layer structures such as a lower photoconductive layer 306 and an upper photoconductive layer 307 may be used (see FIG. 3B).
The surface protective layer 303 is generally a non-single crystal (preferably amorphous) material a-SiC (H, X) containing a silicon atom as a base and containing a carbon atom and, if necessary, a hydrogen atom or a halogen atom. A non-single-crystal (preferably amorphous) material a-SiN (H, X) containing a nitrogen atom and a hydrogen atom or a halogen atom as necessary, or a carbon atom as a base, If necessary, it is formed of non-single crystal carbon (preferably amorphous carbon) a-C (H, X) containing a hydrogen atom or a halogen atom.
Alternatively, the interface between the photoconductive layer 302 and the surface protective layer 303 may be continuously changed, and an antireflection layer may be provided to control the interface reflection of the portion.

<Toner used in the present invention>
The method for producing the toner used in the present invention is not particularly limited, and a suspension polymerization method, an emulsion polymerization method, an associative polymerization method, a kneading pulverization method, and the like are used.
In the production method of a polymerization method toner, generally, a release agent, a plasticizer, a charge control agent, a cross-linking agent, a colorant, and a magnetic component such as a magnetic substance are added to a polymerizable monomer. In addition, other additives, for example, an organic solvent, a high molecular weight polymer, a dispersing agent and the like which are added in order to reduce the viscosity of the polymer produced by the polymerization reaction are appropriately added. Then, the compound (monomer system) in which the blend is uniformly dissolved or dispersed by a disperser such as a homogenizer, a ball mill, a colloid mill, or an ultrasonic disperser is added to an aqueous medium containing a dispersion stabilizer. Suspend.
At this time, the particle size of the obtained toner particles becomes sharper by using a high-speed disperser such as a high-speed stirrer or an ultrasonic disperser to obtain a desired toner particle size at a stretch. The polymerization initiator may be added at the same time when other additives are added to the polymerizable monomer, or may be mixed immediately before being suspended in the aqueous medium. Further, a polymerization initiator dissolved in a polymerizable monomer or a solvent can be added immediately after granulation and before starting the polymerization reaction.
As the dispersion stabilizer, known surfactants and organic / inorganic dispersants can be used. Among them, inorganic dispersants are unlikely to produce harmful ultrafine powders, and because of their steric hindrance, dispersion stability is obtained, so even if the reaction temperature is changed, stability is not easily lost, and cleaning is easy and does not adversely affect the toner. Can be preferably used.
In the polymerization step, the polymerization is performed at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. When the polymerization is carried out in this temperature range, the release agent or wax to be sealed inside is precipitated by phase separation, and the encapsulation becomes more complete. In order to consume the remaining polymerizable monomer, it is possible to raise the reaction temperature to 90 to 150 ° C. at the end of the polymerization reaction.
The toner can also be produced by a dispersion polymerization method in which a toner is directly produced using an aqueous organic solvent that is soluble in monomers and insoluble in the resulting polymer. Furthermore, a method for producing a toner using an emulsion polymerization method represented by a soap-free polymerization method in which a toner is produced by direct polymerization in the presence of a water-soluble polar polymerization initiator, and polymer particles obtained by emulsion polymerization are associated. The toner can also be produced by the aggregation method.
The polymerized toner particles are filtered, washed, and dried by a known method after the polymerization is completed, and the toner can be obtained by mixing and adhering the inorganic fine powder to the surface. Moreover, it is also one of desirable forms that a classification process is included in the manufacturing process to cut coarse powder and fine powder.
When the toner is manufactured by a pulverization method, a known method is used. For example, a binder resin, a magnetic material, a release agent, a charge control agent, and optionally a component such as a colorant and other additives necessary for the toner and other additives are sufficiently mixed by a mixer such as a Henschel mixer or a ball mill. This is melt-kneaded using a heat kneader such as a heating roll, kneader, extruder, etc., and other toner materials such as a magnetic material are dispersed or dissolved in the resin, and cooled and solidified. After pulverization, the toner particles can be obtained by classification and, if necessary, surface treatment. Either the classification or the surface treatment may be performed first. In the classification step, it is preferable to use a multi-division classifier in terms of production efficiency.
The pulverization step can be performed by a method using a known pulverizer such as a mechanical impact type or a jet type. In order to obtain a toner having a specific degree of circularity, it is preferable to perform a process of further pulverizing by applying heat or applying a mechanical impact in an auxiliary manner. Further, a hot water method in which finely pulverized (classified as necessary) toner particles are dispersed in hot water, a method of passing in a hot air stream, or the like may be used.
Examples of means for applying a mechanical impact force include a method using a mechanical impact pulverizer such as a kryptron system manufactured by Kawasaki Heavy Industries, Ltd. or a turbo mill manufactured by Turbo Industry. Moreover, a method using a device such as a mechano-fusion system manufactured by Hosokawa Micron Corporation or a hybridization system manufactured by Nara Machinery Co., Ltd. can be mentioned. This is a method in which the toner is pressed against the inside of the casing by centrifugal force with high-speed rotating blades, and mechanical impact force is applied to the toner by force such as compression force and friction force.
In the case of using the mechanical impact method, a thermomechanical impact in which the processing temperature is a temperature in the vicinity of the glass transition point Tg (Tg ± 10 ° C.) of the toner is preferable from the viewpoint of preventing aggregation and productivity. More preferably, it is particularly effective to improve the transfer efficiency to carry out at a temperature in the range of the glass transition point Tg ± 5 ° C. of the toner.

<Inorganic conductive fine particles used in the present invention>
The inorganic conductive fine particles used in the present invention are particles for charging. Accordingly, there is no problem that the inorganic conductive fine particles exist not only in the state of primary particles but also in the state of aggregation of secondary particles. In any aggregated state, the form is not important as long as the function as a charging particle can be realized as an aggregate.
The number average particle size of the inorganic conductive fine particles is preferably 0.03 μm or more and 2.00 μm or less, more preferably 0.07 μm or more and 1.5 μm or less, 0.15 μm or more, 1.0 μm or less. It is particularly preferred that
When the number average particle size is less than 0.03 μm, it is difficult to release from the toner, and the function as charged particles is hardly exhibited. On the other hand, when it exceeds 2.00 μm, it is difficult to uniformly adhere to the conductive elastic roller.
The number average particle size was measured by extracting 100 particles by observation with an optical or electron microscope, calculating the volume particle size distribution with the maximum horizontal chord length, and taking the 50% particle size as the number average particle size.

Further, the volume resistivity of the inorganic conductive fine particles is 1 × 10 ⁴ Ω · cm or more and 1 × 10 ⁸ Ω · cm or less from the viewpoint of chargeability and charge leakage. The volume resistivity of the inorganic conductive fine particles is preferably 5 × 10 ⁴ Ω · cm or more and 1 × 10 ⁷ Ω · cm or less, more preferably 1 × 10 ⁵ Ω · cm or more and 5 × 10 ⁶ Ω. -It is cm or less.
The volume resistivity was measured by the tablet method and normalized. That is, about 0.5 g of a powder sample is placed in a cylinder with a bottom area of 2.26 cm ² , 15 kg of pressure is applied to the upper and lower electrodes, and at the same time, a voltage of 100 V is applied and the resistance value is measured. The resistivity was calculated.
The inorganic conductive fine particles are preferably white or nearly transparent so as not to interfere with the latent image exposure when leakage from the cleaning member occurs. Further, considering that the inorganic conductive fine particles are partially transferred from the photoreceptor to the recording material, it is desirable that the color recording is colorless or white.
As said inorganic electroconductive fine particles, metal oxides, such as a titanium oxide, a zinc oxide, and an alumina, and what processed these surfaces can be used. Among these, titanium oxide (especially strontium titanate) coated with tin oxide is preferable because the particle size and conductivity can be easily controlled. The inorganic conductive fine particles exemplified above can be produced by a known method.

By interposing the inorganic conductive fine particles in the charging nip portion between the photosensitive member as the image carrier and the conductive elastic roller of the cleaning auxiliary member as the contact charging member, the frictional resistance of the particles increases the frictional resistance. Even if it is a conductive elastic roller that has been difficult to bring in contact with the photosensitive member as it is, it can easily and effectively rotate the difference in rotational speed with respect to the surface of the photosensitive member. It can be brought into contact with each other. Further, the conductive elastic roller is in close contact with the surface of the photoconductor through the inorganic conductive particles, so that the surface of the photoconductor is more frequently contacted. As a configuration for providing the speed difference, the conductive elastic roller is rotationally driven or fixed to provide a speed difference from the photosensitive member.
By providing a speed difference between the rotation speed of the conductive elastic roller and the rotation speed of the photosensitive member, the chance of the inorganic conductive fine particles contacting the photosensitive member at the charging nip portion between the conductive elastic roller and the photosensitive member is greatly increased. And high contactability can be obtained.
The inorganic conductive fine particles present in the charging nip portion between the conductive elastic roller and the photosensitive member rub against the surface of the photosensitive member without any gap, so that charges can be directly injected into the photosensitive member. As a result, the contact charging of the photosensitive member by the conductive elastic roller is dominated by the injection charging mechanism due to the presence of the inorganic conductive fine particles.
As a result, high charging efficiency that cannot be obtained by conventional roller charging or the like can be obtained, and a charging potential almost equal to the voltage applied to the conductive elastic roller can be applied to the photoconductor. Thus, even when a conductive elastic roller is used as the contact charging member, a voltage equivalent to the charging potential required for the photosensitive member is sufficient as the bias applied to the conductive elastic roller, and stable without using a discharge phenomenon. A safe contact charging method or apparatus can be realized. In addition, by carrying the inorganic conductive fine particles in advance on the surface of the charging nip portion or the conductive elastic roller, the above charging performance can be exhibited without any problem from the very beginning of use of the printer.
The charging polarity of the inorganic conductive fine particles after passing through the contact portion (charging nip portion) between the photosensitive member and the conductive elastic roller is preferably opposite to the photosensitive member potential polarity.

A method for supplying the inorganic conductive fine particles to the conductive elastic roller is as follows.
First, even if a sufficient amount of inorganic conductive fine particles are interposed in the charging nip portion between the photosensitive member and the conductive elastic roller, or a sufficient amount of inorganic conductive fine particles are applied to the conductive elastic roller, The use of the inorganic conductive fine particles decreases from the charging nip portion or the conductive elastic roller or the inorganic conductive fine particles are deteriorated due to use. Therefore, when the charging property is lowered, it is necessary to replenish the inorganic conductive fine particles to the charging nip portion and the conductive elastic roller.
Although there may be provided inorganic conductive fine particle supply means for supplying inorganic conductive fine particles to the surface of the conductive elastic roller, in the present application, the inorganic conductive fine particles are supplied via the surface of the photoreceptor by supplying the inorganic conductive fine particles into the developing device. Is replenished. The inorganic conductive fine particle is an external additive as a charging aid for the toner in the developing device, and is a charging particle in the charging portion.

<Inorganic abrasive fine particles used in the present invention>
As a result of intensive studies by the present inventors, when an inorganic abrasive fine particle is interposed between the photosensitive member and the conductive elastic roller and rubbed, deposits such as discharge generation substances, paper powder, and toner on the high-hardness photosensitive member It has been found that the image can be effectively removed, and the image flow and the fusion of foreign matter onto the photoreceptor can be prevented.
The inorganic abrasive fine particles are fine particles having a rectangular parallelepiped shape. Examples of the inorganic abrasive fine particles having a rectangular parallelepiped particle shape include strontium titanate fine particles, barium titanate fine particles, and calcium titanate fine particles. Among them, strontium titanate fine particles are preferable.
The number average particle size of primary particles of the inorganic abrasive fine particles is preferably 0.03 μm or more and 0.50 μm or less, preferably 0.05 μm or more and 0.30 μm or less, 0.10 μm or more, 0 It is particularly preferable that the thickness is 20 μm or less.
When the number average particle size of the inorganic abrasive fine particles is less than 0.03 μm, the abrasive particles are likely to adhere to the surface of the toner or the photoreceptor, and the polishing effect is insufficient. On the other hand, when the thickness exceeds 0.50 μm, when sandwiched between the blade edge and the photoconductor, the inorganic abrasive fine particles come out in a streak shape, which is liable to cause streaks on the charging roller, photoconductor fusing and scratches. .
The number average particle diameter of the inorganic abrasive fine particles was determined by measuring 100 particle diameters from a photograph taken at a magnification of 50,000 with an electron microscope and calculating the arithmetic average thereof. The particle size was determined from (a + b) / 2, where a is the longest side of the primary particles and b is the shortest side.

The inorganic abrasive fine particles having a rectangular parallelepiped shape suitably used in the present invention are prepared by, for example, dispersing strontium hydroxide in a titania sol dispersion obtained by adjusting the pH of a hydrous titanium oxide slurry obtained by hydrolyzing a titanyl sulfate aqueous solution. It can synthesize | combine by adding a thing and heating to reaction temperature. By setting the pH of the hydrous titanium oxide slurry to 0.5 or more and 1.0 or less, a titania sol having a good crystallinity and a particle size can be obtained.
For the purpose of removing ions adsorbed on the titania sol particles, it is preferable to add an alkaline substance such as sodium hydroxide to the titania sol dispersion. At this time, it is preferable that the pH of the slurry is not 7 or higher so that sodium ions and the like are not adsorbed on the surface of the hydrous titanium oxide. The reaction temperature is preferably about 60 ° C. to 100 ° C., the temperature rising rate is preferably 30 ° C./hour or less in order to obtain a desired particle size distribution, and the reaction time is 3 hours or more and 7 hours or less. preferable.
The inorganic abrasive fine particles thus prepared can be obtained as perovskite crystals having a circularity of 0.89 to 0.91 and a rectangular parallelepiped shape. Since the degree of circularity is small, it is possible to prevent particle rolling at the blade edge, and good scraping properties can be obtained. Further, when the fine particles are in the shape of a rectangular parallelepiped, the scraping property by the ridgeline can be obtained.
FIG. 4 shows an example of an electron micrograph (magnification of 20,000 times) of inorganic abrasive fine particles having a rectangular parallelepiped shape. Thus, the particle shape of the inorganic abrasive fine particles can be confirmed by using an electron micrograph (magnification 20,000 times).
Further, it is preferable that the charged polarity of the inorganic abrasive fine particles after passing through the contact portion between the photoconductor and the conductive elastic roller is the same as the photoconductor potential polarity. Further, the inorganic abrasive fine particles having a rectangular parallelepiped shape may also serve as the inorganic conductive fine particles.
The method for supplying the inorganic abrasive fine particles to the conductive elastic roller can be the same as the method for supplying the inorganic conductive fine particles.

In the present invention, the cleaning auxiliary member is coated with toner, inorganic conductive fine particles and inorganic abrasive fine particles (hereinafter also referred to as toner) on a conductive elastic roller, and the toner, inorganic conductive fine particles and inorganic polishing on the conductive elastic roller are coated. It is preferable that a toner coat member for controlling the amount of fine particles is further provided. As the toner coat member, an elastic blade 501a is preferable as shown in FIG. The elastic blade is preferably in contact with a conductive elastic roller. The elastic blade may be a metal blade or a resin blade, but a metal blade having a thickness of about 0.1 to 0.5 mm is desirable from the viewpoint of durability. As the material of the metal blade, for example, phosphor bronze or stainless steel is preferable.
Further, the toner coat member preferably has a resin for applying tribo at a contact portion between the toner on the conductive elastic roller and the toner coat member. In particular, when it is desired to positively charge the toner or the like, the surface of the toner coat member may be coated with a resin containing a charge control agent.
Further, it is preferable that the toner coat member is in contact with the conductive elastic roller, and the tip of the contacted toner coat member has a floating portion (see FIG. 7C) that is separated from the conductive elastic roller.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited at all to this. In addition, the number of parts in the following composition is part by mass unless otherwise specified.

<Example of photoconductor production>
FIG. 8 is a block diagram of an apparatus for manufacturing a negatively charged electrophotographic photosensitive member by a high-frequency plasma CVD method using a VHF band as a power supply frequency. A conductive substrate 801 is placed in a reaction vessel 802, a reaction gas such as SiH _{4 is} introduced from a gas introduction tube 803, high frequency plasma is generated from the electrodes, and each layer is formed on the substrate. Using this manufacturing apparatus, a charge injection blocking layer and a photoconductive layer were formed under the conditions shown in Table 1 on an φ80 mm aluminum cylinder having a surface roughness (ten-point average height) of Rz 0.3 by cutting the surface. A negative amorphous silicon (a-Si) photoreceptor was produced by sequentially forming a layer, an upper blocking layer, and a surface layer. The obtained photoreceptor had a Vickers hardness (JIS standard) of 1200 kg / m ² .

<Examples of developer production>
Into 709 g of ion-exchanged water, 451 g of a 0.1 M Na ₃ PO ₄ aqueous solution was added and heated to 60 ° C., and then 67.7 g of a 1.0 M CaCl ₂ aqueous solution was gradually added to obtain Ca ₃ (PO _{4 2} ) An aqueous medium containing ₂ was obtained.
Styrene 80 parts n-Butyl acrylate 20 parts Unsaturated polyester resin 2 parts Saturated polyester resin 3 parts Negative charge control agent (monoazo dye-based Fe compound) 1 part Colorant 20-100 parts Atlite (Mitsui Miike Chemical) Machine) to uniformly disperse and mix.
This monomer composition was heated to 60 ° C., and 6 parts of ester wax (maximum value of endothermic peak in DSC 72 ° C.) mainly composed of behenyl behenate was added and dissolved therein. 5 g of a polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile) [a half-life time t _{1/2 at} 60 ° C. of 140 minutes] was dissolved in this to prepare a polymerizable monomer system. .
The polymerizable monomer system was put into the aqueous medium, and the mixture was granulated by stirring at 10,000 rpm for 15 minutes in a TK homomixer (Special Machine Industries Co., Ltd.) at 60 ° C. in an N ₂ atmosphere. . Then, it was made to react at 60 degreeC for 6 hours, stirring with a paddle stirring blade. Thereafter, the liquid temperature was raised to 80 ° C. and stirring was continued for 4 hours. After completion of the reaction, distillation was further performed at 80 ° C. for 2 hours, and then the suspension was cooled and hydrochloric acid was added to dissolve Ca ₃ (PO ₄ ) ₂ . Then, filtration, washing and drying were performed to obtain a non-magnetic one-component toner having a weight average particle diameter of 6.5 μm.
100 parts of the above toner Surface treated with hexamethyldisilazane on silica having a primary particle diameter of 8 nm, and 1.2 parts of hydrophobic silica fine powder having a BET value of 250 m ² / g after the treatment Inorganic abrasive fine particles produced as follows 0.5 part Inorganic conductive fine particles produced as follows 0.5 part (However, 1 part if inorganic conductive fine particles are common with inorganic abrasive fine particles)
And a Henschel mixer (Mitsui Miike Chemical Co., Ltd.) to prepare developer A.

<Production example of inorganic abrasive fine particles>
The hydrous titanium oxide slurry obtained by hydrolyzing the aqueous titanyl sulfate solution was washed with an alkaline aqueous solution. Next, hydrochloric acid was added to the hydrous titanium oxide slurry to adjust the pH to 0.65 to obtain a titania sol dispersion. NaOH was added to the titania sol dispersion, the pH of the dispersion was adjusted to 4.5, and washing was repeated until the electrical conductivity of the supernatant reached 70 μS / cm.
0.97-fold molar amount of Sr (OH) ₂ .8H ₂ O was added to the hydrous titanium oxide, and the mixture was placed in a SUS reaction vessel and purged with nitrogen gas. Furthermore, distilled water was added so that it might be 0.1 mol / liter or more and 2.0 mol / liter or less in terms of SrTiO ₃ to obtain a slurry.
The slurry was heated to 85 ° C. at 8 ° C./hour in a nitrogen atmosphere, and reacted for 5 hours after reaching 85 ° C. After the reaction, the reaction mixture was cooled to room temperature, the supernatant was removed, and washing was repeated with pure water.
In the obtained strontium titanate, the number average particle size of primary particles was 150 nm, and the content of aggregates of 800 nm or more was 0.5 number%. Further, the content of particles having a rectangular parallelepiped shape was 80% by number or more. This particle is hereinafter referred to as particle A.
Further, the particles B were prepared by subjecting the particles to a surface treatment with stearic acid so as to facilitate positive charging. Table 1 shows the physical properties of the obtained particles A and B.

<Example of production of inorganic conductive fine particles>
(Production example of tin oxide coated strontium titanate)
The hydrous titanium oxide slurry obtained by hydrolyzing the aqueous titanyl sulfate solution was washed with an alkaline aqueous solution. Next, hydrochloric acid was added to the hydrous titanium oxide slurry to adjust the pH to 0.65 to obtain a titania sol dispersion. NaOH was added to the titania sol dispersion, the pH of the dispersion was adjusted to 4.5, and washing was repeated until the electrical conductivity of the supernatant reached 70 μS / cm.
0.97-fold molar amount of Sr (OH) ₂ .8H ₂ O was added to the hydrous titanium oxide, and the mixture was placed in a SUS reaction vessel and purged with nitrogen gas. Furthermore, distilled water was added so that it might be 0.1 mol / liter or more and 2.0 mol / liter or less in terms of SrTiO ₃ to obtain a slurry.
The slurry was heated to 85 ° C. at 8 ° C./hour in a nitrogen atmosphere, and reacted for 5 hours after reaching 85 ° C. After the reaction, the mixture was cooled to room temperature, the supernatant was removed, and washing was repeated with pure water. 95 g of the resulting slurry is dispersed in 760 ml of water, while 5 g of titanium dioxide particles having an average particle size of 0.3 μm are dispersed in 25 ml of water, and these dispersed slurries are mixed, stirred and heated to 75 ° C. Then, 25% aqueous sodium hydroxide solution was added dropwise to adjust the pH of the slurry to about 12. Next, an aqueous solution obtained by dissolving 184 g of sodium stannate (containing 96% Na ₂ SnO ₃ .3H ₂ O) in 500 ml of water was added to the dispersion slurry, stirred for 30 minutes, and then added with a 20% aqueous sulfuric acid solution over 90 minutes. The solution was neutralized until the pH became 2.5. The dispersion slurry was aged for 3 hours while maintaining the pH at 2.5 and 75 ° C., then filtered, washed, dried, and baked at 300 ° C. for 2 hours in a horizontal tube furnace in an argon atmosphere. Strontium titanate (inorganic conductive fine particles and inorganic abrasive fine particles) was obtained. This particle is referred to as particle C.

(Production example of tin oxide coated barium sulfate)
95 g of barium sulfate particles having an average particle size of 0.08 μm were dispersed in 760 ml of water. On the other hand, 5 g of titanium dioxide particles having an average particle diameter of 0.03 μm were dispersed in 25 ml of water. These dispersion slurries were mixed, stirred and heated to 75 ° C., and then a 25% aqueous sodium hydroxide solution was added dropwise to adjust the pH of the slurry to about 12. Next, an aqueous solution obtained by dissolving 184 g of sodium stannate (containing 96% Na ₂ SnO ₃ .3H ₂ O) in 500 ml of water was added to the dispersion slurry, stirred for 30 minutes, and then added with a 20% aqueous sulfuric acid solution over 90 minutes. The solution was neutralized until the pH became 2.5. The dispersion slurry was aged for 3 hours while maintaining the pH at 2.5 and 75 ° C., then filtered, washed, dried, and baked in a horizontal tube furnace at 300 ° C. for 2 hours in an argon atmosphere. Barium sulfate (inorganic conductive fine particles) was obtained. The inorganic conductive fine particles contained 2.4% by mass of titanium as TiO ₂ , 50.8% by mass of tin as SnO ₂ , and the remainder was composed of barium sulfate. This particle is referred to as particle D.
Further, particles E, F, G, and H having different tin oxide coating amounts were produced by changing the average particle diameter of barium sulfate, the concentration of sodium stannate, the stirring time, and the neutralization time by the same production method as for particles D.

Table 2 shows the physical properties of the obtained particles C, D, E, F, G, and H.

(Note) For example, “7.5E + 8” indicates “7.5 × 10 8”.

<Example of manufacturing a conductive elastic roller as a cleaning auxiliary member>
A conductive sponge roller was manufactured by a manufacturing method including the following materials: kneading, molding, vulcanization foaming, press-fitting, and polishing.
<Unvulcanized unfoamed raw material composition>
100 parts by mass of ethylene propylene diene rubber [Product name: EPT8075E, manufactured by Mitsui Chemicals, Inc.]
Zinc flower 5 parts by mass Stearic acid 2 parts by mass Carbon black 35-71 parts by mass Calcium carbonate 20 parts by mass Paraffinic oil 50 parts by mass [Product name: PW-380, manufactured by Idemitsu Kosan Co., Ltd.]
Mercaptobenzothiazole (vulcanization accelerator) 2 parts by mass Zinc dibutylcarbamate (vulcanization accelerator) 1 part by mass Diethyl thiuram disulfide (vulcanization accelerator) 2 parts by mass Sulfur (vulcanizing agent) 2 parts by mass ADCA (foaming agent) ) 40 parts by mass [Brand name: VINYHALL AC # 3, manufactured by Eiwa Kasei Co., Ltd.]
As the heating device, a vulcanizing can (vulcanizing device using pressurized steam) was used, the temperature of the heating furnace was 160 ° C., and the heating time was 60 to 90 minutes so that the international rubber hardness was 35 degrees. A conductive elastic layer produced in the form of a sponge rubber tube was pressed into a conductive support coated with an adhesive and subjected to an adhesive heating treatment, followed by polishing with a traverse polishing machine to obtain a conductive sponge roller.
The produced conductive sponge roller has a diameter of 16 mm, a wall thickness of 3 mm (support diameter of 10 mm), an international rubber hardness of 35 degrees, and a foamed cell average diameter of 250 μm. Conductive elastic rollers (sponge rollers) A, B, C, D, and E having different electric resistances were manufactured by changing the amount of carbon to be dispersed to 68, 45, 40, 71, and 35 parts by mass, respectively. Table 3 shows resistance values of the obtained conductive elastic rollers (sponge rollers) A, B, C, D, and E. The resistance value (Ω) was measured by applying a DC voltage of 300 V while rotating by contacting an aluminum cylinder with an outer diameter of 30 mm at 15 mN / mm in an environment of a temperature of 23 ° C. and a humidity of 5% RH.

<Toner coat member>
In this example, a phosphor bronze blade having a thickness of 0.10 mm, a free length of 10 mm, was used as the toner coat member. The contact pressure with the conductive elastic roller was set to 15 mN / mm. Further, a phosphor bronze blade blade provided with a positive charge imparting resin (hereinafter also referred to as a coated blade tip resin) for applying tribo at the tip of the phosphor bronze blade was also produced. For the installation of the toner coat member, three patterns shown in a) to c) of FIG. 7 were used. FIG. 7C shows that the toner coat member is in contact with the conductive elastic roller, and the tip of the contacted toner coat member has a floating portion that is separated from the conductive elastic roller. In this floating portion, the distance from the tip of the toner coat member to the surface of the conductive elastic roller is 1 mm.

<Contact charging device (primary charging device)>
As a contact charging device for primary charging, a discharge charging roller and a charge injection magnetic brush roller were produced.
The discharge type charging roller is an elastic roller, and a manufacturing method will be described below.
(1) Production of base layer Epichlorohydrin rubber (trade name: Epichromer CG102, manufactured by Daiso Corporation) 1
00 parts by weight, 30 parts by weight of calcium carbonate as a filler, 1 part by weight of colored grade carbon (trade name: Seast SO, manufactured by Tokai Carbon Co., Ltd.) as a reinforcing material for improving polishing, 4 parts by weight of zinc oxide Then, 10 parts by mass of DOP as a plasticizer, 0.5 part by mass of 2-mercaptobenzimidazole as an anti-aging agent, and 4 parts by mass of quaternary ammonium perchlorate were kneaded in a pressure kneader for 30 minutes. Furthermore, 1 part by mass of Noxeller DM as a vulcanization accelerator, 1.0 part by mass of Noxeller TS as a vulcanization accelerator, and 1.2 parts by mass of sulfur as a vulcanization agent were added and kneaded with an open roll for 15 minutes.
The rubber mixture is extruded into a cylindrical shape using a rubber extruder, and is first vulcanized in steam at 160 ° C. for 80 minutes using a vulcanizing can, and a conductive elastic base layer rubber primary vulcanization tube. Got.
Next, a thermosetting adhesive (trade name: METALOC U-20) of metal and rubber was applied to a cylindrical conductive support (steel, nickel plated on the surface) and air-dried. This conductive support was inserted into the conductive elastic base layer rubber primary vulcanization tube, and then subjected to secondary vulcanization at 160 ° C. for 2 hours and curing of the adhesive in an electric oven to obtain an unpolished layer. . Both ends of the rubber portion of the unpolished layer were cut off and the rubber portion was polished with a rotating grindstone to obtain a crown-shaped conductive elastic base layer having an end diameter of 16.00 mm and a center diameter of 16.10 mm.
(2) Preparation of surface layer ADCA (trade name: VINYHALL AC # 3C average particle size 8 μm, manufactured by Eiwa Kasei Kogyo Co., Ltd.) is classified with an elbow jet classifier to obtain fine powder ADCA (average particle size 2 μm) of 10 μm or less. It was.
400 parts by mass of a lactone-modified acrylic polyol (trade name: Plaxel DC2016, manufactured by Daicel Chemical Industries, Ltd.) was dissolved in 600 parts by mass of MIBK (methyl isobutyl ketone) to obtain a solution having a solid content of 28% by mass. 17.3 parts by mass of a block type isocyanurate type trimer of isophorone diisocyanate (trade name: Bestanat B1370, manufactured by Degussa Huls) and 200 parts by mass of this acrylic polyol solution and an isocyanurate type 3 quantity of hexamethylene diisocyanate 11.0 parts by mass (trade name: Duranate TPA-B80E, manufactured by Asahi Kasei Kogyo), 10 parts by mass of conductive tin oxide, silicone oil (trade name: SH-28PA, manufactured by Toray Dow Corning Silicone Co., Ltd.) 0.11 part by mass and 2.8 parts by mass of the ADCA classification product were added, 200 parts by mass of glass beads having a diameter of 0.8 mm were added thereto, and the mixture was placed in a glass bottle and dispersed for 12 hours using a paint shaker. Finally, the solution was filtered through a 208 mesh screen to obtain a surface coating.
The surface coating was applied to the surface of the charging roller having the conductive elastic base layer by the dipping method. After air drying, it was heated at a curing temperature of 140 ° C. for 120 minutes. The charging roller thus prepared was left in an N / N (normal temperature and normal humidity: 23 ° C./50% RH) environment for 24 hours or more, and the resistance of the charging roller was measured. As a result, it was 1.0 × 10 ⁶ Ω.
The obtained charging roller was brought into contact with the photosensitive member with a contact pressure of 45 mN / mm, and a bias obtained by superimposing an AC bias of 2.7 kHz, 1.1 kVpp, and a sine wave on a DC bias of +620 V was applied. The charging roller is rotated in the direction opposite to the photosensitive member following the rotation of the photosensitive member.
On the other hand, the charge injection type magnetic brush roller is constituted by a nonmagnetic conductive charging sleeve having an outer diameter of 16 mm, a magnet roll included therein, and charged magnetic particles on the charging sleeve. The magnet roll is fixed, and the charging sleeve can be driven to rotate. The maximum magnetic flux density by the magnet at the position facing the photoconductor on the surface of the charging sleeve is 800 ×.
10 ⁻⁴ T (Tesla).
The magnetic brush roller is brought into contact with the photosensitive member so that the charging magnetic particles are coated on the charging sleeve with a thickness of 1 mm and a longitudinal width of 220 mm to form a charging nip having a width of about 5 mm with the photosensitive member. A DC charging bias of −450 V is applied to the charging sleeve from a charging bias application power source, and the charging surface of the photosensitive member is uniformly charged to approximately −450 V. The rotating direction of the charging sleeve of the magnetic brush roller is the reverse direction (forward direction) to the photosensitive member, and 1.5 times the rotating linear velocity of the photosensitive member when the rotating linear velocity of the charging sleeve is 435 mm / sec. It set so that it might become.
In addition, a method for producing the charged magnetic particles will be described below.
Fe ₂ O ₃ : 51.2 mol%, CuO: 24.4 mol%, ZnO: 24.4 mol% were pulverized and mixed in a ball mill, and a dispersant, a binder and water were added to form a slurry, and then sprayed. The granulation operation was performed with a dryer, and after classification, firing was performed at 1120 ° C. The obtained charged magnetic particles were crushed and then classified to obtain charged magnetic particles having a volume average particle diameter of 50 μm. The volume resistance value of the charged magnetic particles was 1 × 10 ⁷ Ωcm.

<Example 1>
An image forming apparatus in which the Canon Digital Copier iR6570 photoconductor, charging device, exposure device, developing device, cleaning device, and pre-exposure device were modified as follows was used.
The negative type amorphous silicon (a-Si) photosensitive member was used as the photosensitive member.
The charge injection type magnetic brush roller was used as the charging device.
The exposure apparatus was set to image exposure.
As the developing device, a developing device for non-magnetic one-component negative toner was used. 300 g of the developer A was charged in the toner hopper of the developing unit. Also, the developer was replaced every time the toner ran out.
The cleaning device is configured as shown in FIG. That is, in the cleaning device of iR6570, the conductive elastic roller B (sponge roller B) is placed at a contact pressure of 45 mN / mm on the upstream side in the rotation direction of the photoconductor and on the downstream side of the transfer member from the contact point of the cleaning blade of the photoconductor. Abutted. The rotation direction of the conductive elastic roller B was set to the forward direction with respect to the rotation of the photosensitive member. Further, the linear velocity of rotation of the photosensitive member was 290 mm / sec, and the speed difference ratio between the linear velocity of rotation of the conductive elastic roller B and the linear velocity of rotation of the photosensitive member was set to 20%. A DC bias of −150 V and a 2.7 kHz / 300 Vpp / sine wave AC bias having the same polarity as the charging polarity of the photosensitive member were applied to the conductive elastic roller in a superimposed manner. Further, when the electric potential of the photoreceptor before and after passing through the conductive elastic roller was measured, it was −50 V before passing through the conductive elastic roller and −130 V after passing through.
In the conductive elastic roller, the particle C (when the particle shape is a rectangular parallelepiped inorganic abrasive fine particle [charged polarity is negatively charged (negative)] and inorganic conductive fine particle [charged polarity is negatively charged (negative)]) Was applied.
The phosphor bronze blade was used as a toner coat member of the conductive elastic roller. Further, as shown in FIG. 7 c), the phosphor bronze blade is in contact with the conductive elastic roller, and the tip of the contacted phosphor bronze blade is separated from the conductive elastic roller. It was set to have a floating part.
The pre-exposure device (static elimination device) is disposed upstream of the contact portion between the photoconductor and the conductive elastic roller in the photoconductor rotation direction and on the downstream side of the transfer member. The pre-exposure device is configured to irradiate the photoconductor with a charge eliminating light from an LED.

Evaluation was carried out by the following evaluation method using the image forming apparatus. The evaluation results are shown in Tables 4, 5 and 6.
(1) Evaluation of cleaning performance In an environment of a temperature of 30 ° C. and a humidity of 85% RH, 500,000 images were printed with 5% images at A4, and whether or not there was any cleaning failure that occurred for all the output images The level was evaluated visually. The evaluation results were ranked as follows.
(Evaluation criteria)
A: No cleaning failure at all.
○: Fusion due to poor cleaning occurs on the photoconductor, but the image is not affected.
Δ: Streaks due to poor cleaning of several sheets are present but not noticeable.
×: One or more sheets have a noticeable cleaning defect on the image.

(2) Evaluation of image flow In an environment of a temperature of 30 ° C. and a humidity of 85% RH, 100,000 images were printed with an A4 5% image. After the 100,000 images were printed, the main unit was turned off and left in the same environment for 48 hours, and then A4 output a total of 200 digital halftone images and 5-point character images, 100 images each for evaluation. The evaluation results were ranked as follows.
(Evaluation criteria)
A: There is no image flow with 1 to 200 sheets.
○: There is a slight highlight jump in the halftone of 50 or more images, but the characters are good.
Δ: There is a slight highlight jump in the halftone of the image from the first sheet, but the characters are good.
X: An image flow blurring from the first sheet to characters occurs.

(3) Evaluation of chargeability 1 After printing 10,000 sheets of vertical ruled line images in an environment of a temperature of 23 ° C. and a humidity of 5% RH, a halftone image was printed, and the sponge roller Density unevenness due to non-uniform charging was evaluated.
(Evaluation criteria)
A: No streak.
○: There are slight streaks, but they are hardly visible.
Δ: There are streaks but they are not noticeable.
X: Streaks are conspicuous.

(4) Evaluation of chargeability 2 Under an environment of a temperature of 30 ° C. and a humidity of 85% RH, after printing 10,000 sheets as a vertical ruled line image, a halftone image was printed, and a sponge roller The density unevenness due to non-uniform charging was evaluated.
(Evaluation criteria)
○: No streak.
Δ: There are streaks but they are not noticeable.
X: Streaks are conspicuous.
XX: Current leak occurs.

(4) Evaluation of latent image memory ghost Under an environment of temperature 30 ° C. and humidity 85% RH, one image is printed with a black circle near the tip and a halftone at the rear edge (ghost chart) at A3. Then, it was evaluated whether a black circle ghost attributed to the latent image memory could be seen in the halftone.
○: Ghost is not seen.
Δ: Ghost can be confirmed, but it is not noticeable even if it exists.
X: A ghost can be confirmed and is conspicuous.

(5) Evaluation of sponge roller durability Under a temperature of 30 ° C. and humidity of 85% RH, 500,000 images were printed with 5% images at A4, and halftone images after image durability were evaluated. Thus, the durability of the sponge roller surface was evaluated.
A: No uneven charging due to "sagging" on the sponge roller surface.
○: Charging unevenness due to “sagging” on the surface of the sponge roller is slight and hardly recognized.
Δ: Some uneven charging due to “sagging” on the surface of the sponge roller can be confirmed, but is not noticeable.
X: Poor charging due to “sagging” on the surface of the sponge roller occurs, and the image is conspicuous.

<Comparative Examples 1-3>
In Example 1, the configuration of the cleaning device is changed from a) in FIG. 6 to b) in FIG. 6 (Comparative Example 1), c) in FIG. 6 (Comparative Example 2), and d) in FIG. 6 (Comparative Example 3). Evaluation was carried out in the same manner except that. Here, FIG. 6 b) shows a configuration in which a charging member by corona discharge is disposed between the contact point of the cleaning blade of the photosensitive member and the conductive elastic roller, and no bias is applied to the conductive elastic roller. . FIG. 6C shows a configuration in which a charging member by corona discharge is provided upstream of the conductive elastic roller in the rotation direction of the photosensitive member, and no bias is applied to the conductive elastic roller. FIG. 6d shows a configuration in which a conductive fur brush roller is disposed upstream of the cleaning blade contact point and a bias is applied to the conductive fur brush roller. The results are shown in Tables 4 and 5.

<Examples 2 to 16 and Comparative Examples 4 to 9>
In Example 1, the type of conductive elastic roller (sponge roller), the presence / absence of a coating blade tip resin, the type and charge polarity of inorganic conductive fine particles, the type and charge polarity of inorganic abrasive fine particles having a rectangular parallelepiped shape, and Evaluation was carried out in the same manner except that the presence or absence of AC superposition was changed as shown in Table 6. The results are shown in Table 6.

<Examples 17 to 28 and Comparative Examples 10 to 11>
In Example 1, the charging roller was used in the charging device, and the type of conductive elastic roller (sponge roller), presence / absence of the coating blade tip resin, the type and charge polarity of the inorganic conductive fine particles, and the particle shape were rectangular parallelepiped. The evaluation was carried out in the same manner except that the type of the inorganic fine abrasive particles, their charging polarity, and the presence or absence of AC superposition were changed as shown in Table 7. Results are shown in Table 7.
Shown in

<Examples 29 and 30>
In Example 5, a configuration in which a minute gap (200 μm) is provided between the conductive elastic roller and the phosphor bronze blade (FIG. 7a)) (Example 29), and the phosphor bronze blade is in contact with the conductive elastic roller The evaluation was carried out in the same manner except that the configuration was such that there was no floating portion where the tip of the abutted phosphor bronze blade was separated from the conductive elastic roller (FIG. 7b)) (Example 30). . The results are shown in Table 8.

As can be seen from the results in Tables 4 to 8 above, a cleaning auxiliary member having a conductive elastic roller is disposed on the upstream side of the photosensitive member rotation direction and on the downstream side of the transfer member from the contact point of the photosensitive member with the cleaning blade. The roller is a roller that contacts the photosensitive member through inorganic conductive fine particles and inorganic abrasive fine particles having a rectangular parallelepiped shape, and rotates with a circumferential speed difference from the photosensitive member. A DC bias is applied to the conductive elastic roller. As a result, charge injection is performed on the photoconductor to assist charging of the photoconductor, and the photoconductor is rubbed at the same time, so that deterioration of the surface of the photoconductor due to charging can be suppressed. Good cleaning performance can be maintained while suppressing
From the comparison between Example 1 and Comparative Examples 1 to 3, it is possible to mechanically and electrostatically reduce the adhesion force between the toner and the photoreceptor by simultaneously injecting charges while rubbing the photoreceptor with a sponge roller. Suggested to be good for cleaning, actually good.
As in Examples 4 to 6, 10 to 16, 20 to 22, and 26 to 30, the charging polarity of the inorganic conductive fine particles is set to be opposite to the potential polarity of the photosensitive member (that is, opposite to the bias applied to the charging roller). Further, since the surface of the sponge roller is coated with inorganic conductive fine particles, the chargeability is further improved. On the other hand, as in Examples 1, 2, 5, 7, 8, 11, 13 to 18, 21, 23, 24, 27, 29, and 30, the inorganic abrasive fine particles have the same polarity (i.e., charged) as the potential polarity of the photoreceptor. By setting the same polarity as the applied bias of the roller, the inorganic abrasive fine particles are easily supplied to the cleaning blade, and the cleaning property is improved. This phenomenon occurs due to a potential difference near the downstream exit of the contact nip between the conductive elastic roller and the photosensitive member. That is, the phenomenon is that the surface potential of the elastic conductive roller is about -150 V near the exit at the downstream end of the contact nip between the conductive elastic roller and the photosensitive member, and the surface potential on the photosensitive member side is about -130 V. This is considered to be due to the fact that the conductive fine particles or inorganic abrasive fine particles easily move selectively to either the sponge roller or the photoconductor.

When an AC bias is superimposed on the conductive elastic roller as in Examples 1 to 6, 13 to 22, 29, and 30, the latent image memory of the photoconductor is easily erased, and latent image ghost is less likely to occur.
As in Examples 1 to 16, 29, and 30, when the primary charging is the charge injection method, it is possible to further suppress deterioration in image quality due to image flow.
Further, regarding the installation method of the toner coat member with respect to the sponge roller of Table 8, as seen in the results of Examples 5, 29 and 30, the toner coat member is not adhered and released by contacting the toner coat member. Since the inorganic conductive fine particles and the inorganic abrasive fine particles easily move to the surface of the sponge roller, the sponge roller surface is easily covered with the inorganic conductive fine particles and the inorganic abrasive fine particles, and the durability of the sponge roller is improved. Further, if the floating portion is formed at the tip of the toner coat member to easily collect the toner, the chance of contact between the toner and the surface of the sponge roller increases, and the inorganic conductive fine particles and the inorganic abrasive fine particles are easily moved to increase durability. improves.

In the above embodiment, strontium titanate fine particles were used as the inorganic polishing fine particles having a rectangular parallelepiped shape. However, it is considered that the same effect can be obtained by using barium titanate fine particles and calcium titanate fine particles.
The recording material may be an intermediate transfer member such as an intermediate transfer drum or an intermediate transfer belt. In this case, the toner image is transferred again from the intermediate transfer member to a secondary recording medium such as paper, but it is considered that the same effect as in the above embodiment can be obtained.

1 is a schematic configuration diagram of an image forming apparatus using an image forming method according to the present invention. 1 is a schematic cross-sectional view of a charge injection type contact charging device. It is a layer structure model figure of an amorphous silicon photoconductor. 4 is an electron micrograph of inorganic abrasive fine particles having a rectangular parallelepiped shape. It is a partial expanded sectional view of a cleaning device. FIG. 3 is a schematic sectional view of the configuration of the cleaning device used in Example 1 and Comparative Examples 1 to 3. 6 is a schematic cross-sectional view of a cleaning device used in Examples 5, 29, and 30. FIG. It is sectional drawing of an amorphous silicon photoconductor manufacturing apparatus.

Explanation of symbols

101 photoconductor (image carrier; drum)
102 Primary charging device (charging roller)
103 Laser scanner (exposure means)
DESCRIPTION OF SYMBOLS 104 Developing device 104a Non-magnetic toner developing roller 104b Developer layer thickness regulating blade 104c Developer stirring and conveying screw shaft 105 Transfer device 106 Post-transfer charger (recording material separating charger; corona charger)
DESCRIPTION OF SYMBOLS 107 Fixing device 108 Static elimination member 109 Cleaning apparatus 109a Cleaning blade 109b Cleaning auxiliary member (rubbing auxiliary member; conductive elastic roller)
109c Toner coating member 109d Transfer residual toner conveying screw 202 Charge injection type charging device 202a Charged magnetic particle 202b Nonmagnetic conductive charging sleeve 202c Magnet roll 301 Base 302 Photoconductive layer 303 Surface protective layer 304 Lower charge injection blocking layer 305 Upper charge injection Blocking layer 306 Lower photoconductive layer 307 Upper photoconductive layer 501a Elastic blade as toner coat member 501b Cleaning blade 501c Conductive elastic roller 501d Photoconductor 800 Vacuum processing device 801 Conductive substrate 802 Reaction vessel 803 Gas introduction tube 804 High frequency electrode 805 High-frequency power supply system 806 Substrate support 807 Exhaust pipe 808 First high-frequency power supply 809 First matching box 810 Rotating shaft 811 Motor 812 Reduction gear 81 The power distribution unit 814 shield 815 and second high-frequency power source 816 second matching box

Claims (14)

A charging step for charging the surface of the photosensitive member with a contact charging device, a latent image forming step for forming an electrostatic latent image on the charged photosensitive member by exposure, and a developing device for developing the electrostatic latent image formed on the photosensitive member A developing process for forming a toner image by developing the toner contained in the toner, a transfer process for transferring the toner image on the photoconductor to a transfer material by a transfer member, and a cleaning device for the transfer residual toner on the photoconductor An image forming method including a cleaning step of removing with a cleaning blade in contact with the photoconductor,
The photoconductor is a photoconductor having a photoconductive layer composed of a non-single crystal material based on silicon atoms,
A cleaning auxiliary member having a conductive elastic roller is disposed on the upstream side of the photosensitive member rotation direction and on the downstream side of the transfer member from the contact point of the cleaning blade of the photosensitive member.
The conductive elastic roller is a roller that comes into contact with the photosensitive member through inorganic conductive fine particles and inorganic abrasive fine particles having a rectangular parallelepiped shape and rotates with a circumferential speed difference from the photosensitive member,
A DC bias is applied to the conductive elastic roller,
The volume resistivity of the inorganic conductive fine particles is 1 × 10 ⁴ Ω · cm or more and 1 × 10 ⁸ Ω · cm or less,
A resistance value of the conductive elastic roller is 1 × 10 ⁴ Ω or more and 1 × 10 ⁸ Ω or less.   2. The image forming method according to claim 1, wherein the inorganic conductive fine particles have a number average particle diameter of 0.03 μm or more and 2.00 μm or less.   3. The image forming method according to claim 1, wherein the rectangular parallelepiped inorganic abrasive fine particles have a number average particle diameter of 0.03 μm to 0.50 μm.   An international rubber hardness (IRHD) of the conductive elastic roller is 20 degrees or more and 50 degrees or less, and a contact linear pressure between the conductive elastic roller and the photoconductor is 10 mN / mm or more and 100 mN / mm or less. The rotational direction of the conductive elastic roller is the forward direction with respect to the rotation of the photoconductor, and the speed difference ratio between the linear velocity of rotation of the conductive elastic roller and the linear velocity of rotation of the photoconductor is 1% or more. The image forming method according to claim 1, wherein the image forming method is 80% or less.   5. The image forming method according to claim 1, wherein the rectangular parallelepiped inorganic polishing fine particles are fine particles of strontium titanate, fine particles of barium titanate, or fine particles of calcium titanate.   6. The image forming method according to claim 1, wherein a linear velocity of rotation of the photosensitive member is 250 mm / sec or more and 600 mm / sec or less.   The image forming method according to claim 1, wherein an AC bias is further applied to the conductive elastic roller.   The contact charging device is provided downstream of the cleaning blade contact point in the rotation direction of the photosensitive member, and the contact charging device is a charge injection method in which the inorganic conductive fine particles are rubbed and charged with the photosensitive member. The image forming method according to claim 1, wherein the image forming method is an image forming method. A neutralizing member for neutralizing the photosensitive member is further disposed on the upstream side of the photosensitive elastic roller in the rotational direction of the photosensitive member and on the downstream side of the transfer member, and after removing the photosensitive member by the neutralizing member, 9. The image forming method according to claim 1, wherein a DC bias having the same polarity is applied to the conductive elastic roller to charge the surface of the photoreceptor.   The image forming method according to claim 9, wherein a charge polarity of the inorganic conductive fine particles after passing through a contact portion between the photoconductor and the conductive elastic roller is opposite to a photoconductor potential polarity.   11. The image formation according to claim 9, wherein a charge polarity of the inorganic abrasive fine particles after passing through a contact portion between the photoconductor and the conductive elastic roller is the same as a photoconductor potential polarity. Method.   The image forming method according to claim 1, wherein the inorganic abrasive fine particles having a rectangular parallelepiped shape also serve as the inorganic conductive fine particles.   The cleaning auxiliary member is further provided with a toner coat member for controlling the amount of the toner, inorganic conductive fine particles and inorganic abrasive fine particles on the conductive elastic roller, and the toner coat member is disposed on the conductive elastic roller. 13. The image forming method according to claim 10, further comprising a resin for applying tribo at a contact portion between the toner and the toner coat member.   The toner coating member is in contact with the conductive elastic roller, and the tip of the contacted toner coating member has a floating portion separated from the conductive elastic roller. Image forming method.