JP2009128842A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an image forming apparatus in which lubricant is supplied to a surface of an image carrier by a blade cleaning system, and which achieves stable cleaning over a long term without causing image deletion and fusion or the like by uniformly applying as small amount of lubricant as possible to the surface of the image carrier so that the surface of the image carrier may be covered with the lubricant. <P>SOLUTION: An abrasive having a cubic and/or rectangular parallelepiped particle shape and having ≥30 nm and ≤300 nm particle size of primary particles and the lubricant are supplied to the surface of the image carrier. When the supply amount of the abrasive is defined as A(μg/cm<SP>2</SP>), the supply amount of the lubricant is defined as B(μg/cm<SP>2</SP>), discharge current amount flowing from an electrifying member to the image carrier is defined as ΔIac(mA), and tapered abrasion loss of the image carrier is defined as T(mg), they satisfy relation of 0.5×ΔIac/T≤A+10B≤5×ΔIac/T and 1≤A/B≤20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile machine that forms an image using an electrophotographic process.

  In a conventional general electrophotographic recording type image forming apparatus, an electrophotographic photosensitive member as an image carrier is uniformly charged by a charging means such as a charging roller, and image exposure, for example, a laser beam is applied thereto. Irradiation produces an electrostatic latent image. This latent image is developed as a toner image by reversal development or normal development by the developing means to be visualized. The toner image is electrostatically transferred to a recording medium by a transfer unit such as a transfer roller, and then fixed on the recording medium by applying heat and pressure by a fixing unit such as a heat fixing device. The surface of the photoreceptor after the transfer of the toner image to the recording medium is cleaned by removing residual toner by a cleaning device, and is prepared for the next image forming process.

  Conventionally, a cleaning method using an elastic blade (cleaning blade) made of polyurethane or the like is often employed as a cleaning method for removing untransferred toner from the surface of a photoconductor after a toner image has been transferred because of its good cleaning properties.

  The physical properties of the cleaning blade and the manner of contact with the photoconductor greatly depend on the ease of cleaning and the surface properties of the photoconductor depending on the degree of adhesion of the transfer residual toner to the photoconductor. Also, the cleaning properties are greatly affected by the physical properties such as toner shape, particle size, and material. Therefore, it is necessary to select a blade suitable for that and set it to an appropriate angle and contact load with respect to the photoreceptor. In the actual selection and setting of the cleaning blade, the present condition is that the optimum condition is found through repeated trial and error.

  On the other hand, the cleaning performance and the abrasion level of the surface layer of the photoreceptor differ depending on the actual operating environment of the image forming apparatus, particularly temperature and humidity, so that it is difficult to clean only with the cleaning blade throughout the endurance life.

  For this reason, some cleaning auxiliary members are provided with a cleaning brush that rotates while contacting the photoconductor. Normally, this cleaning brush is disposed upstream of the cleaning blade in the rotation direction of the photosensitive member, and has a purpose of scraping off transfer residual toner on the photosensitive member after transfer and facilitating cleaning of the cleaning blade. Yes. For this reason, in order to weaken the adhesion force of the transfer residual toner to the photoconductor, there is a case where the cleaning brush is grounded or a bias is applied (Patent Document 1).

  In recent years, various types of image forming apparatuses for obtaining a color image using toners of four colors of yellow, magenta, cyan, and black have been proposed. In addition, there is a toner using fine toner particles close to a spherical shape by a polymerization method or the like because of good transferability. When such a toner is used, it is effective to provide a cleaning brush that is a cleaning auxiliary member as described above, since it is easy to slip through the cleaning blade if the transfer residual toner adheres firmly to the photoreceptor. It is.

  However, the remaining toner is still cleaned by increasing the contact pressure of the cleaning blade to the photosensitive member. As a result, the frictional force with the surface of the photoreceptor increases, and the cleaning blade is more easily damaged and worn. Further, blade squealing or blade turning caused by irregular vibration of the cleaning blade is likely to occur. Therefore, it has become more important to apply a lubricant uniformly to the surface of the photoreceptor to reduce the coefficient of friction on the surface of the photoreceptor.

  Therefore, there is also an apparatus having a mechanism in which a solid lubricant such as zinc stearate is brought into contact with the cleaning brush and applied to the surface of the photoreceptor via the cleaning brush (Patent Document 2).

When a solid lubricant such as zinc stearate is applied to the surface of the photoconductor, a thin film of solid lubricant is formed on the photoconductor to improve the cleaning performance with a cleaning blade, or filming with an external toner additive It is known to prevent. It is also known that this film performance has an effect on image flow.
Japanese Patent Laid-Open No. 04-124690 Japanese Patent Laid-Open No. 09-090839

  However, in a configuration in which such a lubricant is supplied to the photoreceptor surface, it is important to uniformly apply an appropriate amount of the lubricant.

  That is, if the amount of lubricant applied to the surface of the photoreceptor is too small, cleaning failure / fusion / image flow may occur on the surface of the photoreceptor where the lubricant is not properly applied, or the cleaning blade may be worn. Or progress. On the other hand, if the amount of lubricant applied is too large, the surface of the charging member will be contaminated, or it will be easy to be supplied to the cleaning blade as a powder lump, increasing the load on the blade and shortening the blade life.

  Therefore, it is important to apply a lubricant so that the surface of the photoreceptor can be coated as little as possible and uniformly.

  Accordingly, the present invention provides an image forming apparatus that supplies a lubricant to the surface of an image carrier by a blade cleaning method, and applies the lubricant to the surface of the image carrier as little as possible to uniformly apply the surface of the image carrier. It is intended to be able to be coated with a lubricant.

A typical configuration of the image forming apparatus according to the present invention for achieving the above object is as follows:
A rotatable image carrier, a charging member to which an oscillating voltage is applied to charge the surface of the image carrier, and a developing means for developing a latent image formed on the image carrier as a visible image with a developer; A transfer means for transferring the visible image to a recording medium, a cleaning blade that forms a nip portion with the image carrier and scrapes off a transfer residual developer from the surface of the image carrier after the visible image transfer to the recording medium, and a control And an image forming apparatus comprising:
The surface of the image carrier is supplied with an abrasive in which the particle shape is cubic and / or rectangular parallelepiped, and the primary particles have a particle size of 30 nm to 300 nm, and a lubricant,
A supply amount of the abrasive is A (μg / cm ² ),
The supply amount of the lubricant is B (μg / cm ² ),
The amount of discharge current flowing from the charging member to the image carrier is ΔIac (mA),
The Taber wear amount of the image carrier is T (mg),
Then,
0.5 × ΔIac / T ≦ A + 10B ≦ 5 × ΔIac / T
1 ≦ A / B ≦ 20
It is characterized by satisfying the relationship.

  With the above configuration, the lubricant is uniformly applied to the surface of the image carrier in an appropriate amount without excess or deficiency. Thus, stable and good cleaning properties are maintained over a long period of time, image defects such as image flow and fusion are prevented, and stable image characteristics are maintained at a high level.

  Next, an embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings.

[Description of Overall Configuration of Image Forming Apparatus Example]
FIG. 1 is a schematic diagram showing a schematic configuration of an image forming apparatus according to the present embodiment. This image forming apparatus is a transfer type electrophotographic image forming apparatus, which is a multi-function machine having a copier function, a printer function, and a facsimile function.

  A is an image forming unit, and B is a document reading unit (document reading unit) disposed on the top of the image forming unit A. In the document reading section B, 21 is a document table glass, and 22 is a document pressing plate that can be opened and closed with respect to the upper surface of the document table glass 21. The document O is placed on the document table glass 21 with the image surface facing downward according to a predetermined placement standard, and the document pressing plate 22 is placed thereon to set the document O. The document pressing plate 22 may be an automatic document feeder (ADF / RDF) to automatically feed a sheet-shaped document onto the document table glass 21. Reference numeral 23 denotes an original reading unit that is driven to move along the lower surface of the original table glass 21. The document reading unit 23 scans the downward image surface of the set document O on the document table glass 21. As a result, the original image is photoelectrically read as electrical image information and input to the image processing unit of the controller C. The controller C is a control means (control circuit) that comprehensively controls the operation of the image forming apparatus. When an image formation start signal is input, the controller C starts sequence control of the image forming operation.

  In the image forming unit A, reference numeral 1 denotes a drum-type electrophotographic photosensitive member (hereinafter referred to as a photosensitive member) as a rotatable image carrier. The photosensitive member 1 is rotationally driven by a driving mechanism (not shown) at a predetermined speed (process speed) in the clockwise direction of an arrow, in this embodiment, 200 mm / sec. The photoreceptor 1 is formed by applying a layer of a photosensitive material such as OPC to the outer peripheral surface of a cylindrical substrate such as aluminum.

The photoconductor 1 that is rotationally driven is subjected to overall exposure by a pre-exposure lamp (eraser lamp) 7 as a charge eliminating unit. As a result, the surface of the photosensitive member 1 is uniformly discharged, and the electrical memory is erased during the previous image formation. Then, the charge removal surface of the photoreceptor 1 is uniformly charged to a predetermined polarity and potential by the charging member 2. In this example, the charging member 2 is a charging roller (roller-type charging member, roller charger). The charging roller 2 is disposed as a contact charging member in contact with the surface of the photoreceptor 1 (image carrier surface). In this example, the charging roller 2 includes a cylindrical or columnar conductive member (core metal) 2a such as iron or stainless steel, and a volume specific resistance of 10 ⁴ to 10 formed in a roller shape around the conductive member. The resistance layer 2b is 10 ¹² Ω · cm. Further, a surface protective layer 2c having a volume resistivity of 10 ⁴ to 10 ¹² Ω · cm may be provided so as to cover the surface of the resistance layer.

  The charging roller 2 is arranged substantially parallel to the generatrix direction of the photosensitive drum 1, and is driven to rotate as the photosensitive drum 1 rotates by being brought into contact with the photosensitive drum 1. By applying a predetermined charging bias to the conductive member of the charging roller 2 from the charging bias application power source S1, the surface of the rotating photosensitive drum 1 is uniformly charged to a predetermined polarity and potential.

  In this example, as the charging bias, an oscillating voltage obtained by superimposing a predetermined DC voltage on a predetermined AC voltage is applied (AC method), and the surface of the photosensitive drum 1 is uniformly contact-charged to a predetermined dark portion potential VD. ing. Specifically, the AC charging current Iac flowing through the charging roller 2 is controlled at a constant current using a charging bias obtained by superimposing a DC bias of −700 V on a sine wave AC having a frequency of 1850 Hz. As a result, the photosensitive drum 1 is uniformly charged to about −600 V as the dark portion potential VD.

  The charging unit for the photoreceptor 1 may be a proximity charging unit in which the charging roller 2 is disposed in proximity to the surface of the photoreceptor 1. Even if the charging member of the contact charging means is not necessarily in contact with the surface of the object to be charged, it is close to non-contact if the dischargeable region determined by the voltage between the gap and the Paschen curve is reliably ensured between the charging member and the surface of the object to be charged. Even in the arranged configuration, the charged object can be charged. Proximity charging is this, and the charging roller 2 is opposed to the surface of the photosensitive member 1 in a non-contact manner with a small gap of about several tens to several hundreds of μm. An oscillating voltage is applied to the charging roller 2 (AC method) to uniformly charge the surface of the photoreceptor 1 to a predetermined polarity and potential.

  Reference numeral 3 denotes image exposure means (exposure means for forming a latent image). In this example, a laser scanner (laser scanning exposure apparatus) including a laser oscillator, a polygon mirror that rotates at high speed, an F-θ lens, a deflection mirror, and the like. It is. In the copying machine mode, the image processing unit of the controller unit C inputs the electrical image information of the document image input from the document reading unit B to the laser scanner 3. The laser scanner 3 outputs laser light L that is ON / OFF controlled corresponding to the input image information, and scans and exposes the surface of the photoreceptor 1 uniformly charged by the charging unit 2. As a result, a latent image corresponding to the image information of the document O is formed on the surface of the photosensitive drum 1. In this example, an electrostatic latent image of −200 V is formed on the surface of the photoreceptor 1 as the bright portion potential VL.

  In the printer mode, electrical image information input to the controller unit C from an external device (not shown) such as a computer, image scanner, or workstation is processed by the image processing unit. Then, an image is input to the laser scanner 3 and the image forming unit A functions as a printer. In the facsimile reception mode, the electrical image information input from the counterpart facsimile machine (not shown) to the controller unit C is processed by the image processing unit. Then, the image is input to the laser scanner 3 and the image forming unit A functions as a facsimile receiver. In the facsimile transmission mode, electrical image information of the original image photoelectrically read by the original reading unit B is transmitted to the counterpart facsimile machine by the controller unit C.

  The electrostatic latent image formed on the surface of the photoreceptor 1 is developed as a toner image (developed image) by the developer in the developing device 4 as developing means. In many cases, image exposure and reversal development are used in combination.

  In the above, the charging member 2, the image exposure unit 3, and the developing unit 4 are toner image forming units that form a toner image on the photoreceptor 1.

  In this example, the developing device 4 uses a magnetic one-component developing method as a developing method. Reference numeral 41 denotes a non-magnetic developing sleeve having a diameter of 16 mm and includes a fixed magnet roller 42. The developing sleeve 41 is coated with a negative toner having a particle size (average particle size) of 6 μm, and the developing sleeve 41 is rotated at the same speed as the photosensitive member 1 with the distance from the surface of the photosensitive member 1 fixed to 200 μm. A predetermined developing bias voltage is applied from the developing bias power source S2. In this example, the development bias is obtained by superimposing a DC voltage of −500 V and a rectangular AC voltage having a frequency of 1.8 MHz and a peak-to-peak voltage of 1.6 kV, and jumping development between the developing sleeve 41 and the photoreceptor 1 is performed. To do.

  Here, a toner particle size measurement method will be described. As a measuring device, a Coulter counter TA-2 type (manufactured by Coulter Inc.) is used, and an interface (manufactured by Nikka) and a CX-1 personal computer (manufactured by Canon) that output a number average distribution and a volume average distribution are connected. As the electrolytic solution, a 1% NaCl aqueous solution is prepared using primary sodium chloride. As a measuring method, 0.1 to 5 ml of a surfactant, preferably alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the electrolytic aqueous solution, and 0.5 to 50 mg of a measurement sample is further added. The electrolyte solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the particle size distribution of particles of 2 to 40 μm is measured using the Coulter counter TA-2 type using a 100 μ aperture as the aperture. Then, the volume average distribution is obtained. The volume average particle size is obtained from this volume average distribution.

  In the external addition formulation of the developer used in this example, 1.0 part by weight of hydrophobic silica (indefinite shape, average particle diameter of about 20 nm) was externally added to 100 parts by weight of the toner.

  Further, at least one of an abrasive and a lubricant (coating agent) is externally added to the developer. The externally added abrasive and lubricant, or abrasive or lubricant is supplied to the surface of the photoreceptor 1 in a developing process in which the latent image formed on the photoreceptor 1 is developed as a toner image with a developer.

  The lubricant is easily stretched at the nip portion between the cleaning blade 6a and the photosensitive belt 1 to form a thin film on the photosensitive member, thereby improving the cleaning performance by the cleaning blade. Further, filming due to the toner external additive is prevented. It also protects the photoreceptor surface from discharge damage. The film performance is effective in preventing image blur.

  The lubricant needs to be applied substantially over the entire surface of the photoreceptor in order to improve the cleaning performance by the cleaning blade and prevent the charged product generated by the charging means from directly adhering to the photoreceptor surface. is there. Further, the charged product adheres to the lubricant, and in a high-humidity environment, the resistance is reduced in the same manner as the surface of the photoreceptor. Further, since it is applied to the outermost surface of the photosensitive member, it is necessary to transmit light such as image exposure and static elimination light and not to impede charging, development, transfer, and cleaning processes. Therefore, the lubricant is required to have, as a so-called disposable surface layer, ease of film formation (soft and easy to spread), ease of scraping, transparency of the film, and appropriate resistance.

  From these physical properties, examples of the lubricant include powder, a block obtained by solidifying the powder lubricant, or a liquid fatty acid metal salt, fluororesin, silicone oil, and the like. Among these, higher fatty acid metal salts (so-called metal soaps) such as zinc stearate, aluminum stearate, calcium stearate and the like are preferably used. In particular, zinc stearate is preferable because it is excellent in each of the above-described properties and is easy to process into a block body. Also, a wax mainly composed of higher fatty acid and higher alcohol ester is preferably used. In this example, the lubricant is externally added to the developer and supplied onto the surface of the photoreceptor.

  In this example, an inorganic fine powder having a particle shape of a cubic shape (substantially cubic shape) and / or a rectangular parallelepiped shape (substantially rectangular parallelepiped shape) and a primary particle size (average particle size) of 30 nm to 300 nm as an abrasive. (Inorganic powder) was externally added to the developer and supplied onto the surface of the photoreceptor.

  About the average particle diameter of the inorganic fine powder, 100 particle diameters were measured from a photograph taken at a magnification of 50,000 times with an electron microscope, and the average was obtained. The particle diameter was determined as (a + b) / 2, where a is the longest side of the primary particles and b is the shortest side.

  Inorganic fine powder has high hardness and excellent polishing performance. As the inorganic fine powder, for example, strontium titanate, barium titanate, calcium titanate and the like are used.

  By making the inorganic fine powder into a perovskite crystal form having a cubic shape and / or a rectangular parallelepiped shape, a particularly excellent polishing action is exhibited. This is because the particle shape is cubic and / or rectangular parallelepiped, so that the contact area with the object can be increased, and the cubic or cuboid ridge line is in contact with the object. This is considered to be because good scraping properties can be obtained.

  Inorganic fine powders such as strontium titanate in a perovskite crystal preferably have an average primary particle size of 30 nm to 300 nm. If the average particle size is less than 30 nm, the polishing effect of the particles is insufficient. On the other hand, if the average particle size exceeds 300 nm, the polishing effect is too strong. The polishing performance is greatly related to the particle size of the inorganic fine powder, and the larger the particle size, the greater the polishing effect.

  As a means for supplying the inorganic fine powder to the surface of the photoreceptor 1, in addition to the method of externally adding to the developer as in this example, for example, a method of providing an inorganic fine powder supply member in the cleaning device 6, etc. However, it is not particularly limited.

  In this example, as described above, a technique was used in which strontium titanate (particle size: 110 nm) of perovskite crystal as an inorganic fine powder was externally added to the developer of the developing device 4 and supplied onto the photoreceptor.

  The developing method and developer of the developing device 4 are not limited to those described above, and nonmagnetic one-component development, two-component development methods, and the like can also be suitably used.

  On the other hand, the sheet feeding roller 9 of the sheet feeding unit D is driven at a predetermined control timing, and the recording material (transfer sheet, OHP sheet, etc.) P as a recording medium stacked and stored in the sheet feeding cassette 8 is one. The sheets are separated and fed and sent to a registration roller (registration roller) 10. The registration roller 10 controls the skew correction of the recording material P and the transfer timing of the toner image from the photoreceptor 1 to the recording material P. The registration roller 10 controls the leading end of the recording material P fed from the paper feed cassette 8. Take it and stop it. Then, the recording material P is introduced into a transfer nip T which is a pressure contact portion between the photosensitive member 1 and a medium resistance transfer roller (transfer means) 5 by a registration roller 10 which is rotationally driven at a predetermined control timing. . While the recording material P is nipped and conveyed through the transfer nip T, the transfer roller 5 is applied with a transfer bias having a predetermined potential opposite to the toner charging polarity from the transfer bias power source S3. As a result, the toner image formed on the surface of the photoreceptor 1 is electrostatically transferred sequentially to the surface of the recording material P.

  The recording material P that has exited the transfer nip T is separated from the surface of the photosensitive member 1 and guided by the guide member 11, and is heated to a predetermined pressure on the heat fixing roller 12 a of the image heat fixing device 12 as a fixing unit. Then, the toner is introduced into the fixing nip N between the pressure roller 12b and the pressed roller 12b. The recording material P is nipped and conveyed by the fixing roller 12a and the pressure roller 12b in the fixing nip portion N, and receives heat and pressure in the conveyance process. As a result, the toner image is fixed on the surface of the recording material P as a fixed image. Then, the recording material P that has exited the fixing nip N is discharged as an image formed product (copy, print) to the discharge tray 14 by the discharge roller 13.

  Further, the transfer residual toner remaining on the surface of the photoreceptor 1 after separation of the recording material (after transfer of the visible image) is removed by a cleaning device (cleaning means) 6. The photoreceptor 1 whose surface has been cleaned is repeatedly used for image formation. This cleaning device 6 is a blade cleaning device using an elastic cleaning blade (elastic blade) as a cleaning member. The cleaning device 6 includes a cleaning blade 6a supported by a sheet metal 6f, a toner collection sheet 6b, a waste toner collection container 6c, and the like. The cleaning blade 6a is brought into contact with the rotating photoconductor 1 against a counter to form a nip portion with the photoconductor 1.

  The cleaning blade 6a is made of polyurethane rubber that is integrally held at the front end of the sheet metal 6f, and is in contact with the photoreceptor 1 under conditions of a predetermined penetration amount and a set angle. The rubber hardness is preferably 50 to 85 ° (JIS A), more preferably 60 to 80 °. In this example, a cleaning blade 6a having 70 ° urethane rubber is used, a setting angle = 22 °, an intrusion amount is in a range of 0.5 to 1.3 mm, and a contact pressure of the cleaning blade 6a to the photosensitive member 1 is 25 g / It was made to become the range of cm. The contact pressure of the cleaning blade 6a is preferably 10 to 50 g / cm. When the contact pressure of the cleaning blade 6a is less than 10 g / cm, a cleaning failure due to toner slip is likely to occur, and when it exceeds 50 g / cm, it is difficult to obtain satisfactory durability due to wear of the cleaning blade 6a. became.

  In this example, the photosensitive member 1 and some processing means acting on the photosensitive member 1 are used as the process cartridge 15. Specifically, the photosensitive member 1, the charging roller 2, the developing device 4, and the cleaning device 6 are integrally assembled in the cartridge frame 15a and detachably attached to the image forming unit A. As a process cartridge to be used.

[Calculation of discharge current amount ΔIac]
Here, the calculation of the amount of discharge current ΔIac flowing from the charging roller 2 to the photoreceptor 1 will be described in detail.

  As described above, in this example, a charging bias obtained by superimposing a DC bias of −700 V on a sine wave AC having a frequency of 1850 Hz is used, and the AC charging current Iac flowing through the charging roller 2 is controlled at a constant current.

  It can be considered that the impedance Zc between the charging roller 2 and the photosensitive member 1 in this example is represented by the equivalent circuit of FIG. Rc is the resistance of the charging roller 2, Cc is the electrostatic capacity of the charging roller 2, Cd is the electrostatic capacity of the photoreceptor 1, and Cair is the electrostatic capacity of a minute air gap between the charging roller 2 and the photoreceptor 1.

  When no discharge occurs, the following relationship is established between the applied AC voltage Vac (maximum amplitude value; Vpp) and the charging AC current Iac according to the impedance Zc.

Iac = Iz; Iz = α · Vac, α = 1 / (√2 · Zc)
However, when a discharge is occurring, ie
Vac (Vpp) ≧ 2 × Vth (V) Vth: When the discharge start voltage is satisfied, as shown in the graph of FIG.

  Here, Iz indicates a portion where Iac extends linearly (Vac <2 × Vth) and its extrapolated portion (the dotted line portion in FIG. 3 when Vac ≧ 2 × Vth).

  In the description of this example, the difference ΔIac between Iac and Iz is defined as the discharge current amount (μA (mA)).

  Since electric transients are included when discharge is occurring, it is difficult to theoretically determine the discharge current amount ΔIac. Furthermore, the discharge current amount ΔIac is easily influenced by temperature and humidity, contact condition of the charging roller 2, physical properties, toner contamination, and the like, and is not always constant. Therefore, it is necessary to obtain the discharge current amount ΔIac for each printing operation or for every fixed time.

  The discharge current amount ΔIac is calculated by the following equation (1).

ΔIac = Iac−α · Vac (1)
The proportional constant α is obtained from Iac and Vac in an undischarged state. When the ratio of the current Iac to the peak-to-peak voltage Vpp less than the discharge start voltage Vth × 2 (V) is α, AC current such as current flowing to the contact portion (hereinafter referred to as nip current) other than the current due to discharge is α · Vpp. The difference between Iac measured when a voltage equal to or higher than the discharge start voltage Vth × 2 (V) and this α · Vpp is the discharge current.

  In the present embodiment, the discharge current amount ΔIac is controlled to be constant. This control method will be described below.

  The discharge current amount ΔIac changes as the environment and durability are increased when charging is performed under the control of a constant voltage or a constant current. This is because the relationship between the peak-to-peak voltage and the discharge current amount and the relationship between the alternating current value and the discharge current amount are fluctuating.

  In the AC constant current control method, control is performed by the total current Iac flowing from the charging roller 2 as a charging member to the photosensitive member 1 as a member to be charged. For this reason, the amount of discharge current cannot actually be controlled. Even when the constant current control is performed with the same current value, the discharge current amount naturally decreases as the nip current increases due to the environmental variation of the material of the charging roller 2, and the discharge current amount increases as the nip current decreases. For this reason, it has been impossible to completely suppress the increase / decrease in the discharge current amount even with the AC constant current control method.

  Therefore, the present inventors performed control in the following manner in order to always obtain a desired discharge current amount.

  A method of determining the peak-to-peak voltage that becomes the discharge current amount D when the desired discharge current amount is D will be described.

  As shown in FIG. 4, the controller C sequentially applies two points of alternating current (Iac) that is a discharge region and one point of alternating current that is an undischarged region to the charging roller 2 during printing preparation rotation. Then, the peak-to-peak voltage value at that time is measured by the peak-to-peak voltage value measurement circuit 50 (FIGS. 6, 9, and 10).

  Here, at the time of printing preparation rotation, when an image formation start signal is input to the standby image forming apparatus, the main motor is driven to rotate the photosensitive member 1 for a while before the image forming operation starts. This is a period (pre-rotation stroke) during which the image forming apparatus executes a predetermined pre-printing operation.

  The relationship between the peak-to-peak voltage and the alternating current is set in advance so that when the peak-to-peak voltage is zero, the alternating current value is also zero.

  Next, the controller C linearly approximates the relationship between the peak-to-peak voltage and the alternating current using the measured value from the two points in the discharge region and the measured value and the zero point in the non-discharged region. Is calculated.

Equation 2 ... Approximate straight line of discharge region: Yα = αXα + A
Equation 3 ... Approximate straight line of undischarged region: Yβ = βXβ
After that, the AC current (Iac) at which the difference between the approximate straight line Yα of the discharge region and the approximate straight line Yβ of the undischarged region becomes the discharge current amount D is determined by Equation 4.

If the alternating current value for D is Iac1, and the peak-to-peak voltage at that time is Vpp, then Equations 2 and 3 are
Iac1 = αVpp + A Expression a
Iac2 = βVpp Formula b
It becomes. Here, Iac2 is an alternating current value that becomes Vpp in the approximate straight line Yβ of the undischarged region.

Iac1-Iac2 = D... Formula c
From the expressions a, b, and c, the alternating current (Iac) that becomes the discharge current amount D is determined by the expression 4.

Formula 4... Iac = (αD−βA) / (α−β)
Then, the AC current applied to the charging roller 2 is switched to the obtained Iac, the constant current is controlled by the Iac, and the process proceeds to the above-described image forming operation.

  At the time of image formation, Iac1 obtained from the obtained alternating current is applied, and the peak-to-peak voltage at that time is measured.

  In a non-image forming area (between sheets) between the image forming area and the next image forming area, one point of alternating current that is an undischarged area is applied to the charging roller 2 and the peak-to-peak voltage at that time is measured.

  From the newly measured relationship between the peak-to-peak voltage and the alternating current value and the relationship between the peak-to-peak voltage and the alternating current value measured during the print preparation rotation, statistical processing is performed to calculate the following equations 5 and 6. To do.

Equation 5: Approximate straight line of discharge region: Yα = α′Xα + A ′
Equation 6: Approximate straight line of undischarged region: Yβ = β′Xβ
Thereafter, in the same manner as when obtaining the alternating current Iac1 to be applied during printing (image forming operation), the discharge current amount D, which is the difference between the approximate straight line Yα in the discharge area and the approximate straight line Yβ in the undischarged area, using Equation 7. The alternating current Iac3 is determined.

Formula 7... Iac3 = (α′D−βA ′) / (α′−β)
Then, the AC current Iac3 applied to the charging roller 2 is switched to constant current control to form an image.

  Similarly, during the next image formation, the relationship between the peak-to-peak voltage and the alternating current value is measured during printing and between sheets, and the applied alternating current is always corrected while the image forming operation is performed.

  In this way, the discharge current ΔIac was controlled.

[Photoconductor]
1) Photoconductor Production Method FIG. 5 is a layer configuration model diagram of the photoconductor 1 in this example. In this photoreceptor 1, a charge generation layer 1d and a charge transport layer 1e are provided in this order on a support 1a as a photosensitive layer, and on the outermost surface of the photoreceptor having a smaller wear rate (high mechanical strength). A protective layer 1f is provided. Further, a binder layer 1b and an undercoat layer 1c for the purpose of preventing interference fringes may be provided between the support 1a and the charge generation layer 1d.

  As the support 1a, the support itself having conductivity, for example, aluminum, aluminum alloy, stainless steel or the like can be used. In addition, the support or plastic having a layer formed by vacuum deposition of aluminum, an aluminum alloy, an indium oxide-tin oxide alloy, or the like can be used. In addition, a support obtained by impregnating plastic or paper with conductive fine particles (for example, carbon black, tin oxide, titanium oxide and silver particles) together with an appropriate binder resin, or a plastic having a conductive binder resin may be used. it can.

  Further, a binder layer (adhesive layer) 1b having a barrier function and an adhesive function can be provided between the support 1a and the photosensitive layers 1d and 1e. The binder layer 1b can be used to improve the adhesion of the photosensitive layer, improve the coating property, protect the support, cover defects on the support 1a, improve the charge injection from the support 1a, and protect the photosensitive layer from electrical breakdown. Formed for. The binding layer 1b can be formed of casein, polyvinyl alcohol, ethyl cellulose, ethylene-acrylic acid copolymer, polyamide, modified polyamide, polyurethane, gelatin, aluminum oxide, or the like. The film thickness of the binder layer 1b is preferably 5 μm or less, and particularly preferably 0.1 to 3 μm.

  Examples of the charge generation material used for the charge generation layer 1d include (1) azo pigments such as monoazo, disazo and trisazo, and (2) phthalocyanine pigments such as metal phthalocyanine and nonmetal phthalocyanine. Further, (3) indigo pigments such as indigo and thioindigo, and (4) perylene pigments such as perylene acid anhydride and perylene imide may be mentioned. Further, (5) polycyclic quinone pigments such as anthraquinone and pyrenequinone, and (6) squarylium dye may be mentioned. Further, (7) pyrylium salts and thiapyrylium salts, and (8) triphenylmethane-based dyes may be mentioned. Further, (9) inorganic substances such as selenium, selenium-tellurium and amorphous silicon, (10) quinacridone pigments, (11) azulenium salt pigments, and (12) cyanine dyes may be mentioned. Further, (13) xanthene dye, (14) quinoneimine dye, (15) styryl dye, (16) cadmium sulfide, and (17) zinc oxide may be mentioned.

  Examples of the binder resin used for the charge generation layer 1d include polycarbonate resin, polyester resin, polyarylate resin, butyral resin, polystyrene resin, polyvinyl acetal resin, and diallyl phthalate resin. In addition, acrylic resin, methacrylic resin, vinyl acetate resin, phenol resin, silicone resin, polysulfone resin, styrene-butadiene copolymer resin, alkyd resin, epoxy resin, urea resin, and vinyl chloride-vinyl acetate copolymer resin. Can be mentioned. However, it is not limited to these.

  These can be used singly or in combination as a single or mixed or copolymer polymer.

  The solvent used in the charge generation layer coating material is selected from the solubility and dispersion stability of the resin and charge generation material used. As the organic solvent, alcohols, sulfoxides, ketones, ethers, esters, aliphatic halogenated hydrocarbons or aromatic compounds can be used.

  The charge generation layer 1d is well dispersed by a method such as a homogenizer, ultrasonic wave, ball mill, sand mill, attritor or roll mill together with the above-mentioned charge generation material in an amount of 0.3 to 4 times the binder resin and solvent. It is formed by coating and drying. The thickness is preferably 5 μm or less, and particularly preferably in the range of 0.01 to 1 μm.

  In addition, various sensitizers, antioxidants, ultraviolet absorbers, plasticizers, and known charge generating substances can be added to the charge generation layer 1d as necessary.

  Examples of the charge transport material used for the charge transport layer 1e include various triarylamine compounds, various hydrazone compounds, various styryl compounds, and various stilbene compounds. Also, various pyrazoline compounds, various oxazole compounds, various thiazole compounds, various triarylmethane compounds, and the like can be given.

  As the binder resin used to form the charge transport layer 1e, an acrylic resin or a styrene resin is preferable. Further, a resin selected from polyester, polycarbonate resin, polyarylate, polysulfone, polyphenylene oxide, epoxy resin, polyurethane resin, alkyd resin, unsaturated resin, and the like is preferable. Particularly preferred resins include polymethyl methacrylate, polystyrene, styrene-acrylonitrile copolymer, polycarbonate resin and diallyl phthalate resin.

  The charge transport layer 1e is generally formed by dissolving the charge transport material and the binder resin in a solvent and applying them. The mixing ratio (mass ratio) of the charge transport material and the binder resin is about 2: 1 to 1: 2. As the solvent, ketones such as acetone and methyl ethyl ketone, and esters such as methyl acetate and ethyl acetate are used. In addition, aromatic hydrocarbons such as toluene and xylene, chlorinated hydrocarbons such as chlorobenzene, chloroform and carbon tetrachloride, ethers such as tetrahydrofuran and dioxane, and the like are used.

  In applying this solution, for example, a coating method such as a dip coating method, a spray coating method, or a spinner coating method can be used. Drying is preferably performed at 10 ° C to 200 ° C, more preferably at a temperature in the range of 20 ° C to 150 ° C, preferably 5 minutes to 5 hours, and more preferably 10 minutes to 2 hours under blast drying or static drying. It can be carried out.

  The charge transport layer 1e is electrically connected to the above-described charge generation layer 1d, receives charge carriers injected from the charge generation layer 1d in the presence of an electric field, and receives these charge carriers from the protective layer 1f. Has the function of transporting to the interface. The charge transport layer 1e has a limit of transporting charge carriers and cannot be made thicker than necessary. However, the charge transport layer 1e is preferably 5 to 40 μm, particularly preferably 7 to 30 μm.

  Furthermore, an antioxidant, an ultraviolet absorber, a plasticizer, and a known charge transport material can be added to the charge transport layer 1f as necessary.

  Further, the protective layer 1f is applied and cured on the charge transport layer 1e to form a photoconductor having a wear rate of 0.1 to 2.0 mg according to the Taber abrasion test.

2) Method 1 for forming protective layer 1f
As the protective layer 1f of the electrophotographic photoreceptor satisfying the above conditions, a compound obtained by polymerizing a hole transporting compound having two or more chain polymerizable functional groups in the same molecule as shown in the following chemical formula 1 is contained. There is a protective layer to do.

  In the formula, A represents a hole transporting group. P1 and P2 represent a chain polymerizable functional group. P1 and P2 may be the same or different. Z represents an organic residue which may have a substituent. a, b, and d represent 0 or an integer of 1 or more, and a + b × d represents an integer of 2 or more. When a is 2 or more, P1 may be the same or different. When d is 2 or more, P2 may be the same or different. When b is 2 or more, Z and P2 may be the same or different. .

  By polymerizing a hole transporting compound having two or more chain polymerizable functional groups in the same molecule, the compound having a hole transporting ability has at least two crosslinking points in the protective layer 1f. It is incorporated into the three-dimensional crosslinked structure via a covalent bond. The hole transporting compound can be either polymerized alone or mixed with a compound having another chain polymerizable group, and the kind / ratio thereof is arbitrary. As used herein, the compound having another chain polymerizable group includes any monomer or oligomer / polymer having a chain polymerizable group. When the functional group of the hole transporting compound and the functional group of the other chain polymerizable compound are the same group or a group that can be polymerized with each other, they both take a copolymerized three-dimensional crosslinked structure via a covalent bond. Is possible. In the case where both functional groups are functional groups that do not polymerize with each other, the photosensitive layer is a mixture of at least two or more three-dimensional cured products or other chain polymerizable compound monomers in the three-dimensional cured product as a main component. It is comprised as the thing containing the hardened | cured material. It is also possible to form an IPN (Inter Penetrating Network), that is, an interpenetrating network structure by controlling the blending ratio / film forming method well.

  The protective layer 1f can contain at least one selected from the group consisting of a fluorine atom-containing resin, a carbon fluoride, and a polyolefin resin as the lubricant 1g. The following are mentioned as the preferable compound. However, it is not limited to these compounds.

  Preferred examples of the fluorine atom-containing resin include a polymer or copolymer resin of a compound selected from vinyl fluoride, vinylidene fluoride, and chlorotrifluoroethylene, and resin fine particles. In addition, a polymer or copolymer resin of a compound selected from tetrafluoroethylene, hexafluoropropylene, perfluoropropylene, and perfluoroalkyl vinyl ether, and resin fine particles may be mentioned.

  Examples of the carbon fluoride include compounds represented by (CF) n and (C2F) n.

  Preferable polyolefin-based resins include homopolymer resins such as polyethylene resin, polypropylene resin, and polybutene resin, copolymer resins such as ethylene-propylene copolymer, and ethylene-butene copolymer, and resin powder.

  These lubricants 1g can be used alone or in combination of two or more at any ratio.

  Further, the protective layer 1f may contain a dispersant, a dispersion aid, other various additives, a surfactant, and the like of the lubricant 1g.

  By containing at least one of fluorine atom-containing resin, carbon fluoride, and polyolefin resin as the lubricant 1g in the protective layer 1f, the slipperiness and water repellency of the surface of the photoreceptor can be improved. Further, it is possible to prevent deterioration of transfer characteristics and slipperiness due to chemical deterioration of the protective layer 1f due to charging, development, transfer, etc. during repeated use, and further deterioration of electrical characteristics such as sensitivity reduction and potential reduction. In addition, it is possible to suppress the occurrence of image defects such as filming, fusing, cleaning failure, and image blur / flow even during repeated use. Particularly preferable results are obtained when the fluorine-containing resin is used.

  The ratio of 1 g of the lubricant contained in the protective layer 1f is preferably 1 to 70%, more preferably 5 to 50%, based on the total weight of the layer to be the protective layer 1f. If the amount of the lubricant 1g is more than 70%, the mechanical strength of the layer to be the protective layer 1f tends to be lowered, and if it is less than 1%, the water repellency and slipperiness of the layer to be the protective layer 1f may not be sufficient.

  It is also possible to contain a charge transport material in the protective layer 1f containing the cured product of the hole transport compound having the chain polymerizable group.

  In general, the protective layer 1f is formed by applying a polymerization reaction after applying a solution containing the hole transporting compound. It is also possible to form a protective layer by reacting a solution containing the hole transporting compound in advance to obtain a cured product and then dispersing or dissolving in a solvent again. As a method for applying these solutions, for example, a dip coating method, a spray coating method, a curtain coating method, and a spin coating method are known. The dip coating method is preferable from the viewpoint of efficiency / productivity.

  The hole transporting compound having a chain polymerizable group is preferably polymerized by radiation. The greatest advantage of polymerization by radiation is that a polymerization initiator is not required, which makes it possible to produce a very high-purity three-dimensional photosensitive layer and to ensure good electrophotographic characteristics. In addition, because it is a short and efficient polymerization reaction, it is highly productive, and because of its good radiation transparency, it inhibits curing when a thick film or additives such as additives are present in the film. The influence of is very small. However, depending on the type of the chain polymerizable group and the type of the central skeleton, the polymerization reaction may not easily proceed, and in this case, it is possible to add a polymerization initiator within a range that does not affect the reaction. The radiation used at this time is an electron beam and a γ-ray. In the case of electron beam irradiation, any type such as a scanning type, an electro curtain type, a broad beam type, a pulse type, and a laminar type can be used as an accelerator. When irradiating an electron beam, irradiation conditions are very important in order to develop electrical characteristics and durability. The acceleration voltage is preferably 250 kV or less, and optimally 150 kV or less. The dose is preferably in the range of 10 kGy to 1000 kGy. When the accelerating voltage exceeds the above, the electron beam irradiation damage tends to increase on the characteristics of the photoreceptor. Further, when the dose is less than the above range, the curing tends to be insufficient, and when the dose is large, the photoreceptor characteristics are likely to deteriorate.

3) Method 2 for forming protective layer 1f
Further, as the protective layer 1f, a charge transport material having at least one group selected from the group consisting of a curable phenol resin and a hydroxyalkyl group, a hydroxyalkoxy group or a hydroxyphenyl group which may have a substituent. There is a protective layer to contain.

  The curable phenol resin, which is a binder resin used for the protective layer, is generally a resin obtained by a reaction between phenols and formaldehyde. There are two types of phenolic resins: a resole type obtained by reacting with phenol with an excess of formaldehyde and reacting with an alkali catalyst, and a novolak obtained by reacting with phenol and an excess of phenol with formaldehyde. Divided into molds.

  The resol type is also soluble in alcohol and ketone solvents, and is heated to form a cured product by three-dimensional crosslinking polymerization. On the other hand, the novolak type generally does not cure even when heated as it is, but forms a cured product by adding a formaldehyde source such as paraformaldehyde or hexamethylenetetramine and heating.

  In general, the resol type is used as a varnish for paints, adhesives, cast products and laminates, and the novolak type is mainly used as a molding material or a binder.

  The phenolic resin used as the binder resin can be either the above-mentioned resol type or novolak type, but it should be cured without adding a curing agent, or the resol type should be used because of its operability as a paint. Is preferred.

  These phenol resins can be used singly or in combination of two or more, and a resol type and a novolak type can also be mixed and used.

  For example, the protective layer 1f can be formed using a polyhydroxymethylated bisphenol compound having two or more hydroxymethyl groups.

  The skeleton of the above-described bisphenol compound has a structure represented by the following chemical formula 2.

  In the formula, X represents a single bond or a divalent linking group. R1 and R2 are each a halogen atom, an aryl group, a vinyl group, an optionally substituted alkyl group, an optionally substituted cyclic alkyl group, or an optionally substituted alkoxy group as a substituent. Represents an aryl group which may have a substituent or a heterocyclic group which may have a substituent.

  When this polyhydroxymethylbisphenol compound is subjected to a heat treatment, an ether bond or a further condensation reaction proceeds by a condensation reaction between hydroxymethyl groups to form a methylene bond. Alternatively, a methylene bond is formed by a condensation reaction between the hydroxymethyl group and the ortho-position or para-position hydrogen atom of the phenolic hydroxyl group. When these condensation reactions occur between various molecules, a three-dimensional cured film having a high crosslinking density can be obtained. These condensation reactions are essentially reactions that are not hindered by moisture and oxygen in the air, and proceed sufficiently even in a system to which a charge transport material is added. The crosslinking reaction by heat treatment of the polyhydroxymethyl bisphenol compound has a feature that it is not necessary to add a curing catalyst generally used for thermosetting. Therefore, when such a compound is used as the protective layer 1f (protective layer) of the electrophotographic photosensitive member, problems such as an increase in residual potential and a decrease in resistance of the protective layer 1f due to the residual curing catalyst do not occur.

  In addition, the polyhydroxymethyl bisphenol compound does not require the addition of a curing catalyst, and the hydroxymethyl group itself is sufficiently stable to moisture unlike isocyanates and silicone resins. Are better.

  The protective layer 1f is formed by applying a coating obtained by dissolving or diluting a curable phenolic resin with a solvent or the like onto the photosensitive layer, and a polymerization reaction occurs after the coating to form a cured layer. The polymerization proceeds by heat addition and condensation reaction, and after the protective layer is applied, it is heated to cause a polymerization reaction to produce a polymer cured layer.

  The charge transport material having a hydroxyalkyl group, a hydroxyalkoxy group or a hydroxyphenyl group which may have a substituent is preferably a triphenylamine derivative.

  In addition, examples of the substituent that the hydroxyphenyl group may have include halogen atoms such as fluorine, chlorine, bromine, and iodine, and optionally substituted methyl group, ethyl group, propyl group, and butyl group. An alkyl group is mentioned. In addition, an alkoxy group such as a methoxy group, an ethoxy group, a propoxy group and a butoxy group which may have a substituent, and an aryl group such as a phenyl group, a naphthyl group, an anthryl group and a pyrenyl group which may have a substituent Can be mentioned. Or heterocyclic groups, such as a pyridyl group, a thienyl group, a furyl group, and a quinolyl group which may have a substituent, are mentioned.

  Among the charge transport materials, the charge transport material having a hydroxyalkyl group or a hydroxyalkoxy group is preferably a compound having a specific structure represented by the following chemical formula 3.

  In the formula, R11, R12 and R13 each represent a divalent hydrocarbon group having 1 to 8 carbon atoms which may be branched. α, β and γ each have a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aryl group or a substituent as a substituent. Represents a benzene ring which may have one or more heterocyclic groups which may be substituted. a1, b1 and c1 are 1 or 0, and m1 and n1 are 0 or 1.

  Further, the charge transport material is uniformly dissolved or dispersed in the coating material for producing the protective layer 1f, and is applied. The mixing ratio of the charge transporting material and the curable phenolic resin is preferably a mass ratio of charge transporting material / curable phenolic resin = 0.1 / 10 to 20/10, particularly 0.5 / 10 to 10/10. preferable. If the amount of the charge transport material is too small relative to the curable phenol resin, the effect of lowering the residual potential is reduced, and if it is too much, the strength of the protective layer may be weakened.

The protective layer 1f essentially does not move charges as a resistor, but maintains the sensitivity of the electrophotographic photosensitive member provided with the protective layer by transferring charges with a charge transport material contained in the protective layer. This reduces the residual potential. Therefore, it is not necessary to set the volume resistivity as a resistor low. By setting the volume resistivity to 1 × 10 ¹² (Ω · cm) or more, the flow of the formed electrostatic latent image is high. Can be suppressed in dimension.

  In the electrophotographic photosensitive member having the protective layer 1f described above, by further containing fluorine atom-containing resin fine particles, the releasability on the surface of the electrophotographic photosensitive member can be improved at a higher level.

  As the fluorine atom-containing resin fine particles, ethylene tetrafluoride, ethylene trifluoride chloride resin, hexafluoroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, ethylene difluoride dichloride resin and the like are preferable. In addition, it is preferable to appropriately select one or more of these copolymers. In particular, tetrafluoroethylene resin and vinylidene fluoride resin are preferable. The molecular weight distribution and particle size of the resin particles can be appropriately selected and are not particularly limited.

  As a solvent for preparing the coating liquid for the protective layer 1f, the polyhydroxymethylbisphenol compound and the charge transport material are sufficiently dissolved, and further, a lower charge transport layer or charge generation layer that is in contact with the coating liquid for the protective layer 1f A solvent that does not adversely affect the above is preferred.

  Accordingly, alcohols such as methanol, ethanol and 2-propanol, ketones such as acetone, cyclohexanone and methyl ethyl ketone, and esters such as methyl acetate and ethyl acetate can be used as the solvent. In addition, ethers such as tetrahydrofuran and dioxane, aromatic hydrocarbons such as toluene and xylene, and halogenated hydrocarbons such as chlorobenzene and dichloromethane can be used. Further, these may be mixed and used. Among these, the most preferred solvents are alcohols such as methanol, ethanol and 2-propanol.

  Conventionally, known charge transport materials are generally insoluble or hardly soluble in solvents of alcohols, and uniform dissolution in polyhydroxymethyl bisphenol compounds is difficult. However, when it contains a hydroxy group as a charge transport material, it is soluble in a solvent containing alcohols as a main component and has little influence on the lower layer such as a charge transport layer.

  As a method for applying the protective layer 1f, general coating methods such as a dip coating method, a spray coating method, a spinner coating method, a roller coating method, a Meyer bar coating method, and a blade coating method can be used.

  An antioxidant additive may be added to the protective layer 1f for the purpose of preventing deterioration of the protective layer 1f due to adhesion of an active substance such as ozone or NOx generated during charging.

4) Method for evaluating abrasion resistance of photoreceptor surface The Taber abrasion test method is performed by mounting a sample on a sample stage of a Taber abrasion tester (manufactured by YSS Taber Yasuda Seisakusho). A load of 500 g was applied to each rubber wear wheel (CS-0) with wrapping tape (Fuji Photo Film product name: C2000) on the two surfaces, and the weight loss of the sample after 1000 revolutions was applied to the precision balance. Measured.

  In this example, a total of four types of photoconductors were obtained: a photoconductor on which three types of protective layers 1f were formed and a photoconductor on which no protective layer was provided.

5) Photosensitive member production example 1 (electrophotographic photosensitive member a)
An aluminum cylinder (JIS A3003 aluminum alloy) having a length of 260.5 mm and a diameter of 30 mm was used as the support 1a. On top of this, a 5% by mass methanol solution of polyamide resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) was applied by an immersion method to form an undercoat layer 1c having a thickness of 0.5 μm.

  Next, the following charge generation layer coating material was prepared, which was dip-coated on the undercoat layer 1c and dried at 90 ° C. for 10 minutes to form a charge generation layer 1d having a thickness of 0.17 μm. .

Charge generation layer coating material a: Crystal of hydroxygallium phthalocyanine having the strongest peak at a diffraction angle 2θ ± 0.2 of 28.1 ° in X-ray diffraction of CuKα as a charge generation material 3 parts b: Polyvinyl butyral 2 parts c: Cyclohexanone: 100 parts The above material is dispersed in a sand mill using 1 mmφ glass beads for 1 hour, and 100 parts of methyl ethyl ketone is added thereto for dilution.

  Next, the following charge transport layer coating material was prepared, dip coated on the charge generation layer 1d, and dried in hot air at 110 ° C. for 1 hour to form a charge transport layer 1e having a thickness of 13 μm.

Paint for charge transport layer a: Charge transport material compound of the following chemical formula 4: 7 parts

b: Polycarbonate resin (Iupilon Z400, manufactured by Mitsubishi Engineering Plastics) 10 parts c: Monochlorobenzene 105 parts d: Dichloromethane 35 parts In this example, reversal development is used. The photoreceptor is an organic photoreceptor in which the three layers 1c + 1d + 1e are overlaid on the aluminum cylinder 1a having a diameter of 30 mm as described above, and the protective layer 1f is formed as follows. That is, it is an organic photoreceptor obtained by applying and curing a surface layer containing a compound obtained by polymerizing a hole transporting compound of the following chemical formula 5 by electron beam irradiation as the protective layer 1f.

  45 parts of the hole transporting compound of the following chemical formula 5 are dissolved in 55 parts of n-propyl alcohol.

  Further, 5 parts by weight of tetrafluoroethylene fine particles were added, and a coating material for the surface protective layer was prepared by dispersing with a high-pressure disperser (microfluidizer, manufactured by Microfluidics).

  After applying this paint on the photoconductor of the four layers 1a + 1c + 1d + 1e, an electron beam is irradiated under the conditions of an acceleration voltage of 150 KV and a dose of 40 kGy to form a protective layer 1f having a film thickness of 3 μm. Obtained. The photoreceptor was subjected to a Taber abrasion test and found to be 0.5 (mg / 1000 rotations).

6) Photosensitive member production example 2 (electrophotographic photosensitive member b)
Only the irradiation conditions of the electron beam were changed by the same manufacturing method as that of Photoconductor Production Example 1. Here, the protective layer 1f was formed with an electron beam acceleration voltage of 150 KV and a dose of 10 kGy to obtain an “electrophotographic photosensitive member b”. The photoreceptor was subjected to a Taber abrasion test and found to be 1.0 (mg / 1000 rotations).

7) Photoconductor Production Example 3 (Electrophotographic Photoconductor c)
On the same four-layer 1a + 1c + 1d + 1e photoconductor as in Photoconductor Production Example 1, the following protective layer coating solution was prepared, dip-coated on the charge transport layer 1e, and dried in hot air at 145 ° C. for 1 hour. A protective layer 1f having a thickness of 3 μm was provided. Here, the film thickness of the protective layer 1f was measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd.).

Coating liquid for protective layer a: Tetrakishydroxymethyl-bisphenol in which all the ortho-position hydrogen atoms of the phenolic hydroxyl group of bisphenol represented by the following chemical formula 6 are substituted with hydroxymethyl groups as a curable phenol resin as a binder resin Compound: 100 parts

  b: Charge transport material represented by the following chemical formula 7: 70 parts

c: Tetrafluoroethylene fine particles: 42 parts d: Ethanol: 150 parts are mixed and dissolved in a solvent dispersed by a high-pressure disperser (Microfluidizer, manufactured by Microfluidics).

  The photoreceptor having the protective layer produced as described above is referred to as “electrophotographic photoreceptor c”. The photoreceptor was subjected to a Taber abrasion test and found to be 1.5 (mg / 1000 rotations).

8) Photosensitive member production example 4 (electrophotographic photosensitive member d)
The same four layers 1a + 1c + 1d + 1e as in Photoconductor Production Example 1 were obtained, and an “electrophotographic photoreceptor d” without a protective layer was obtained. A Taber abrasion test was conducted on this photoreceptor, and the result was 3.0 (mg / 1000 rotations).

  Examples 1 to 34 and Comparative Examples 1 to 9 are shown below. The lubricant used in each example and each comparative example is a fatty acid metal salt (metal soap), which is “zinc stearate” in the form of a powdery or solidified powder block, and an abrasive (inorganic powder). Is a "perovskite crystal strontium titanate".

  Here, the particle size (average particle size) of primary particles of the abrasive (perovskite crystal strontium titanate) used in Examples and Comparative Examples is 110 nm.

[Examples 1 to 5]
In this embodiment, both the lubricant and the abrasive are externally added to the developer of the developing device 4 and supplied to the surface of the photoreceptor.

Concentration ratio of the supply amount A (μg / cm ²⁾ and the transfer efficiency and the transfer residual toner as a supply amount A (μg / cm ²⁾ to the photosensitive member surface of the lubricant to the photoreceptor surface of the abrasive (waste toner) Estimated from

  As the photoreceptor 1, the above-mentioned “electrophotographic photoreceptor a” (Taber abrasion amount 0.5 mg) was used. The charging roller 2 was brought into contact with the photoreceptor 1 at a load of 50 gr / cm, and constant current control was performed by the above-described method so that the discharge current was 50 μA.

  Image evaluation was performed with the above-described image forming apparatus configuration. In the evaluation mode, a durability test of 50,000 sheets was performed intermittently for a chart with a printing rate of 5%. The test environment was a high-temperature and high-humidity (30 ° C./80%) environment and a normal temperature and low-humidity (23 ° C./5%) environment, and image flow and filming were evaluated. The evaluation results are shown in Table 1.

[Examples 6 to 8]
The same as in Example 1 except that the above-mentioned “electrophotographic photoreceptor b” (Taber wear amount 1.0 mg) was used as the photoreceptor 1, and similarly, the evaluation was performed by varying the supply amounts of the abrasive and the lubricant. It was. The evaluation results are shown in Table 1.

[Example 9]
The same as in Example 1 except that the above-mentioned “electrophotographic photoreceptor c” (Taber abrasion amount 1.5 mg) was used as the photoreceptor 1, and similarly, the evaluation was performed by varying the supply amounts of the abrasive and the lubricant. It was. The evaluation results are shown in Table 1.

[Example 10]
The same as in Example 1 except that the above-mentioned “electrophotographic photosensitive member d” (Taber wear amount: 3.0 mg) was used as the photosensitive member 1, and the evaluation was performed by similarly changing the supply amounts of the abrasive and the lubricant. It was. The evaluation results are shown in Table 1.

[Examples 11 to 14]
In this embodiment, the charging roller 2 is in contact with the photosensitive member 1 by its own weight. When the self-weight contact is used, the gap formed by the charging roller 2 and the photosensitive member 1 becomes unstable as compared with the load contact, and local charging failure (so-called sandy ground) is likely to occur. In order to prevent this, the current amount must be supplemented so that charging failure does not occur even in the portion where the gap is unstable, that is, where the discharge is unstable, so the total discharge current amount increases. In this example, a discharge current of 150 μA was required for the disappearance of the sand. Other configurations were the same as those in Example 1, and the evaluation was performed in the same manner by changing the supply amounts of the abrasive and the lubricant. The evaluation results are shown in Table 2.

[Examples 15 to 17]
The same as Example 11 except that the above-mentioned “electrophotographic photoreceptor b” (Taber wear amount 1.0 mg) was used as the photoreceptor 1. Similarly, the evaluation was performed by changing the supply amounts of the abrasive and the lubricant. went. The evaluation results are shown in Table 2.

[Examples 18 to 19]
The same as Example 11 except that the above-mentioned “electrophotographic photoreceptor c” (Taber abrasion amount 1.5 mg) was used as the photoreceptor 1. Similarly, the evaluation was performed by varying the supply amounts of the abrasive and the lubricant. went. The evaluation results are shown in Table 2.

[Example 20]
Except for using the above-mentioned “electrophotographic photosensitive member d” (Taber wear amount: 3.0 mg) as the photosensitive member 1, the same as in Example 11, and similarly, the evaluation was performed by changing the supply amounts of the abrasive and the lubricant. went. The evaluation results are shown in Table 2.

[Examples 21 to 23]
In this embodiment, as shown in FIG. 6, as a charging device for the photosensitive member 1, a gap holding member 60 is provided at both ends of the charging roller 2 so that the charging roller 2 is close to the photosensitive member 1 with a gap d. It was set as the structure to arrange. That is, the charging device for the photoreceptor 1 is a proximity charging device.

  In this embodiment, the charging roller 2 is held with the photosensitive member 1 with a gap d = 30 μm. Charging by the non-contact charging roller is less stable than contact charging, so that the discharge becomes more unstable than the self-weight contact in Example 11 and a charging failure tends to occur. In order to prevent this, it is necessary to flow a large amount of discharge current.

  FIG. 7 shows a general relationship between the nearest charging interval (gap d) at which uniform chargeability is obtained and the amount of discharge current. The occurrence of charging failure largely depends on the distance between the surface of the photosensitive member and the charging roller surface, so it has a large effect on the circularity of the charging roller 2, etc., but in order to obtain uniform chargeability with the configuration of this embodiment, A discharge current amount of 300 μA was required. The other configurations were the same as in Example 1, and the evaluation was performed by similarly varying the supply amount of strontium titanate of zinc stearate / perovskite crystal. The evaluation results are shown in Table 3.

[Examples 24-26]
The same as Example 21 except that the above-mentioned “electrophotographic photoreceptor b” (Taber wear amount 1.0 mg) was used as the photoreceptor 1. Similarly, the evaluation was performed by changing the supply amounts of the abrasive and the lubricant. went. The evaluation results are shown in Table 3.

[Examples 27 and 28]
The same as Example 21 except that the above-mentioned “electrophotographic photoreceptor c” (Taber wear amount 1.5 mg) was used as the photoreceptor 1. Similarly, the evaluation was performed by changing the supply amounts of the abrasive and the lubricant. went. The evaluation results are shown in Table 3.

[Examples 29 and 30]
Except for using the above-mentioned “electrophotographic photosensitive member d” (Taber wear amount: 3.0 mg) as the photosensitive member 1, the same as in Example 21, and similarly, the evaluation was made by varying the supply amounts of the abrasive and the lubricant. went. The evaluation results are shown in Table 3.

[Comparative Example 1]
Table 4 shows the evaluation results obtained in the same manner as in Example 1, except that the abrasive supply amount was 0.6 μg / cm ² and the lubricant supply amount was 0 μg / cm ² .

[Comparative Example 2]
0 Pg / cm ² the supply amount of the polishing agent, except that the supply amount of lubricant and 0.06 .mu.g / cm ^2, showing the same city as in Example 1, the results of evaluation are shown in Table 4.

[Comparative Example 3]
Table 4 shows the results of evaluation performed in the same manner as in Example 1 except that the abrasive supply amount was 0.03 μg / cm ² and the lubricant supply amount was 0.005 μg / cm ² .

[Comparative Example 4]
Table 4 shows the evaluation results obtained in the same manner as in Example 1 except that the abrasive supply amount was 0.3 μg / cm ² and the lubricant supply amount was 0.01 μg / cm ² .

[Comparative Example 5]
0 Pg / cm ² the supply amount of the polishing agent, except that the supply amount of lubricant and 0.15 [mu] g / cm ^2, showing the same city as in Example 11, the results of evaluation are shown in Table 4.

[Comparative Example 6]
Except that the feed amount of the polishing agent was 0.1 [mu] g / cm ^2, the supply amount of lubricant and 0.11 g / cm ^2, showing the same city as in Example 11, the results of evaluation are shown in Table 4.

[Comparative Example 7]
Table 4 shows the evaluation results obtained in the same manner as in Example 11 except that the abrasive supply amount was 0.1 μg / cm ² and the lubricant supply amount was 0.01 μg / cm ² .

[Comparative Example 8]
Table 4 shows the evaluation results obtained in the same manner as in Example 21 except that the abrasive supply amount was 0.1 μg / cm ² and the lubricant supply amount was 0.04 μg / cm ² .

[Comparative Example 9]
Table 4 shows the evaluation results obtained in the same manner as in Example 21 except that the abrasive supply amount was 0.6 μg / cm ² and the lubricant supply amount was 0.25 μg / cm ² .

From the results of the above Examples 1-30 and Comparative Examples 1-9,
0.5 × ΔIac / T ≦ A + 10B ≦ 5 × ΔIac / T
1 ≦ A / B ≦ 20
Within the range, image flow / fusion did not occur and image formation could be performed satisfactorily.

  Here, as shown in Tables 7 and 8, the numerical setting of the supply amount described in each of the examples and comparative examples in Tables 1 to 4 is an abrasive (inorganic fine powder) and a lubricant (metal) for the developer. This is done by changing the amount of external additive of soap.

The transfer efficiency is obtained from the consumption amount in development and the weight of waste toner as follows: transfer efficiency (%) = (consumption amount−waste toner) / consumption amount × 100. The concentration ratio of the abrasive and the lubricant in the waste toner is determined by how many times it is concentrated by the fluorescent X-ray apparatus as compared with the developing toner. When the supply amount (total amount) after endurance is simply calculated, the amount is calculated as waste toner amount × developed toner external weight part × concentration rate. When estimating the supply amount during durability, supply amount = toner consumption amount × (1−transfer efficiency / 100) × development toner from the transfer toner and toner consumption predicted by transfer efficiency and concentration rate, video count, etc. that can be predicted in advance. It is obtained by the weight part of external additive × concentration rate. In order to make this per unit area, it is obtained by the following formula: supply amount (μg / cm ² ) = supply amount / (moving distance in the circumferential direction of the photoreceptor surface when a charging bias is applied × image forming width). The reason why the charging is applied, not the total moving distance of the surface of the photosensitive member, is that the surface of the photosensitive member is damaged when the bias is applied. The supply amount is obtained as described above. Since transfer efficiency and the like may vary depending on the use environment, a means for creating and controlling an environment table is preferable.

  In Examples 1-30 and Comparative Examples 1-6, in a system in which an abrasive and a lubricant are externally added to the developer of the developing device 4 and supplied to the photoreceptor, the abrasive supplied to the photoreceptor and A part of the lubricant adheres to the recording material at the transfer portion and is taken away. The supply amounts A and B of the abrasive and the lubricant to the photosensitive member are amounts on the image carrier between the transfer portion and the cleaning nip portion.

  In the relational expression of claim 1, ΔIac is a value determined in order to satisfy charging uniformity in various use environments, and T is a value determined by the characteristics of the photoconductor. Therefore, it is necessary to change the values of A and B in order to establish the relational expression. Although the embodiment has been described using a 5% chart, this relational expression must be established no matter what the printing rate is. For example, when a large amount of charts with extremely low printing rates are output, the abrasive and lubricant are hardly supplied to the surface of the photoreceptor. In view of this, blackening is applied at the time of non-image formation to supply an abrasive and a lubricant on the surface of the photoreceptor so that the relational expression is satisfied. On the contrary, when the printing rate is high and the supply amount is excessive, adjustment is performed by increasing the pre-multi-rotation time.

  The above relational expression will be described below.

  The main function of the lubricant is to coat the surface of the photoreceptor and protect it from discharge damage. For that purpose, it is necessary to apply uniformly on the surface of the photoreceptor. Where the lubricant film is not formed or insufficient, the surface of the photoreceptor is directly subjected to discharge damage due to electrification, thereby causing image flow / fusion. As the photoconductor wear rate is smaller (Taber wear amount T is smaller), the surface of the photoconductor due to discharge damage is not refreshed and deterioration is accumulated. For this reason, it is necessary to securely coat with a lubricant so as not to be damaged by discharge. Further, the discharge damage depends on the amount of discharge current described above, and the level becomes worse as the amount of discharge current increases. Therefore, the more the discharge current amount ΔIac is, the more the surface of the photoreceptor must be coated and protected. That is, as the value of ΔIac / T is larger, it is necessary to surely coat the surface of the photoreceptor with the lubricant. Therefore, when a large amount of lubricant is externally added to the developer in order to sufficiently supply the lubricant to the surface of the photoreceptor, there may be a problem that the density decreases due to contamination of the developing sleeve by the lubricant.

  Further, in a system in which a solidified lubricant block body (fatty acid metal salt rod), which will be described later (Example 32), is scraped with a brush member and applied to the surface of the photoreceptor, the block body is reduced in hardness and is easily scraped. To do. Or, if you try to increase the supply amount by increasing the contact pressure of the brush member to the block body and increasing the scraping ability, the lubricant is supplied to the surface of the photoreceptor as a lump of powder. It becomes the situation that is easy to be done. Therefore, not only uniform application cannot be performed, but there is a risk of causing local damage to the cleaning blade and causing poor cleaning. In addition, the consumption of the lubricant block body becomes intense, and satisfactory durability cannot be obtained.

  On the other hand, there is also a method of polishing and removing the discharge product adhering to the surface of the photoreceptor with an abrasive. Among these abrasives, the perovskite crystal strontium titanate is particularly effective. This is because the particle shape is approximately a cube or a rectangular parallelepiped, the contact area with the object can be increased, and the ridge line of the cube or the rectangular parallelepiped can abut against the object to obtain a good rubbing property. This is thought to be possible.

  When this abrasive is also supplied in a large amount, the scraping property of the discharge product is enhanced, but if it is used by adding a large amount to the developer, the developability may be lowered. Moreover, there is a risk of deteriorating the contamination level on the surface of the charging roller.

  According to the present invention, the total supply amount can be reduced by using a lubricant and an abrasive in combination.

  For example, in Example 1, the total supply amount A + B = 0.11 and the image flow / fusion is good, whereas in Comparative Example 1, A + B = 0.6, regardless of the supply amount, the image flow / fusion Wearing has occurred.

  Further, as a result of intensive studies by the present inventors, it has been found that the supply amount of the lubricant is more effective than the supply amount of the abrasive, and in fact, the value of A + 10B is the image flow / It was found that there is a correlation with phenomena such as fusion.

  From this point of view, in Example 1, A + 10B = 0.2, in Comparative Example 1, A + 10B = 0.6, and even in Comparative Example 2, A + 10B = 0.6. It was good, and in Comparative Examples 1 and 2, it was bad.

  The synergistic effect when this lubricant and abrasive are used in combination can be explained as follows. In order to prevent the occurrence of image flow / fusion, it is necessary to cover the surface of the photosensitive member with a lubricant, but in order to perform this with a small amount of lubricant, it is necessary to cover the surface uniformly and thinly. In the conventional configuration, the spreading action of the lubricant is usually performed by the cleaning blade, but in the case of this embodiment, a more uniform film property can be obtained by the presence of the abrasive at the same time. Originally, the abrasive used in this embodiment is considered to have fine abrasiveness from its particle size and shape, and its performance leveles out uneven supply of the lubricant and gives uniform film properties. Conceivable.

  Further, since the coated lubricant is present on the surface of the photosensitive member in a state where the discharge product is adsorbed, if the discharge product adsorbing portion is not removed, image flow occurs. It is considered that the scraping action of the discharge product adsorbing portion is mainly performed at the nip portion of the cleaning blade and is slid by the cleaning blade. The removal of the discharge product is effectively performed by supplying the abrasive to the nip portion of the cleaning blade. In other words, it is possible to uniformly apply the lubricant / removal of the discharge product adsorbing portion by using the abrasive together, and as a result, it is sufficient to reduce the total amount of both of them compared to using the abrasive and the lubricant alone. Can be obtained.

  However, if the supply amount is reduced to the condition of 0.5 × ΔIac / T> A + 10B (Comparative Examples 3, 7, and 8), image flow / fusion is generated.

  In Comparative Example 9, the image flow / fusion was good, but the supply amount of the lubricant was increased so as to satisfy the condition of A + 10B> 5 × ΔIac / T, so that the developability deteriorated due to durability. Under this condition, even if the block body of the lubricant is scraped and applied by the brush member, as described above, the cleaning blade may be locally damaged and cause a cleaning failure. In addition, the consumption of the lubricant block body becomes intense and satisfactory durability cannot be obtained.

  In Comparative Examples 4 and 6, it is in the range of 0.5 × ΔIac / T ≦ A + 10B ≦ 5 × ΔIac / T, but the reason for the failure is because it is outside the range of 1 ≦ A / B ≦ 20.

  When A / B is less than 1 (Comparative Example 6), the effect of applying the lubricant uniformly by the abrasive / removability of the discharge product adsorbing portion is exhibited. On the other hand, if A / B is more than 20 (Comparative Example 4), the lubricant is peeled off excessively, and the coating action by the lubricant for the purpose of protecting the photoreceptor surface cannot be obtained.

[Example 31]
In this embodiment, a member that slides on the surface of the photosensitive member 1 in the longitudinal direction of the photosensitive member (longitudinal direction of the image carrier) is disposed downstream of the transfer roller 5 in the rotational direction of the photosensitive member (rotating direction of the image carrier). Set up. Specifically, as shown in FIG. 8, a non-rotating brush member 6 i is disposed as a cleaning auxiliary member in the waste toner collecting container 6 c of the cleaning device 6 for the photosensitive member 1. The brush member 6i is in contact with the photoconductor 1 on the upstream side of the cleaning blade 6a in the photoconductor rotation direction. The brush member 6i reciprocates in the longitudinal direction of the photosensitive member by a driving unit (not shown), and slides on the surface of the photosensitive member 1 in the longitudinal direction.

As the brush fiber, rayon, acrylic, polyester or the like is preferably used, and carbon or metal powder may be included to impart conductivity. The brush portion preferably has a thickness of 30 denier or less and a density of 1550 to 77500 / cm ² (1 to 500,000 / inch ² ) or more so that the surface of the photoreceptor and the transfer residual toner can be uniformly contacted. . In this example, the brush fiber was 6 denier, 15500 / cm ² (100,000 / inch ² ), the length of the bristle was 5 mm, and the resistance of the brush was 6 × 10 ³ Ω · cm. The brush member 6i is configured to reciprocate 5 mm in the longitudinal direction.

  Other configurations were the same as those in Example 1, and the same evaluation was performed. As a result, no image flow / fusion occurred and good image formation was performed.

  In the configuration of the first embodiment, an image can be formed normally without any problem. However, when a large amount of the same image pattern such as a vertical ruled line is continuously printed, the image pattern may be affected. This is because the lubricant and the abrasive are supplied onto the surface of the photoconductor in the development process, and therefore, depending on the polarity of each particle and the adhesion to the toner, the image / non-image part is supplied in a different manner. This is because bias occurs.

  In this embodiment, the lubricant and the abrasive are both supplied to the image portion (toner developing portion). Under such conditions, if an area with an extremely small number of printed portions continues, supply of lubricant and abrasive becomes insufficient, and image flow and fusion are likely to occur.

  In the configuration of the present embodiment, even if there is a bias in the supply of lubricant and abrasive on the surface of the photoreceptor after the transfer process, it is uniformized by the brush member 6i that reciprocates in the longitudinal direction. Therefore, stable image formation can be performed from start to finish regardless of the image pattern.

[Example 32]
In this embodiment, as shown in FIG. 9, a cleaning brush (brush roller) 6 d that rotates as a cleaning auxiliary member is disposed in a waste toner collection container 6 c of the cleaning device 6 for the photosensitive member 1. The cleaning brush 6 d is in contact with the photoconductor 1 on the upstream side of the cleaning blade 6 a in the rotation direction of the photoconductor 1. In addition, a solid lubricant (solidified lubricant block body) 6e is disposed in contact with the cleaning brush 6d. Reference numeral 6g denotes an urging member that always brings the solid lubricant 6e into contact with the cleaning brush 6d with a predetermined pressing force. The cleaning brush 6d is driven to rotate in the same direction as the rotation direction of the photosensitive drum at the contact portion with the photosensitive member 1.

The cleaning brush 6d is formed by weaving conductive fibers on a base fabric and winding it on a core metal having a diameter of 6 mm to form a roll brush having a diameter of 16 mm. In this example, an acrylic conductive yarn having a thickness of 6 denier is used as the conductive fiber, and the fiber is implanted in a base fabric with a W weave so that the fiber density is 50K / inch ² and formed into a sheet shape. Wrapping to ensure conduction with gold. The contact amount with respect to the photosensitive member 1 is 1 mm and the contact width is 7 mm.

  The cleaning brush 6d is rotationally driven in the arrow direction at a peripheral speed (first peripheral speed) VB. That is, the photosensitive member 1 and the cleaning brush 6d move in the same direction at the contact portion and rub against each other. The cleaning brush 6d is rotationally driven by a driving source M1 such as a stepping motor. The controller C can control the motor driver 51 to arbitrarily change the rotational speed of the drive source M1, that is, the rotational speed of the cleaning brush 6d. In this embodiment, the peripheral speed ratio between the cleaning brush 6d and the photosensitive member surface is 120%.

  As the solid lubricant 6e, zinc stearate, aluminum stearate, calcium stearate or the like is preferably used. In this embodiment, a block body (zinc stearate bar) in which zinc stearate is solidified is used and is brought into contact with the cleaning brush 6d. The lubricant in the block body is scraped off by the rotation of the cleaning brush 6d. When the rotating photoconductor 1 and the cleaning brush 6d rub against each other, the lubricant on the cleaning brush is applied to the surface of the photoconductor. The supply amount of the lubricant onto the surface of the photosensitive member was estimated from the consumption amount of the lubricant block 6e.

  In Example 32, the supply amount B of the lubricant (metal soap) to the photoreceptor measures the consumption amount of the solid lubricant. After that, the movement distance of the photosensitive member is calculated, and the supply amount is estimated from “consumption amount / (photosensitive member movement distance during image formation × image formation width). The adjustment of the lubricant supply amount B is performed by adjusting the peripheral speed of the cleaning brush. Or by changing the contact pressure of the cleaning brush against the solid lubricant or the amount of penetration.

  No lubricant is externally added to the developer of the developing device 4. Add abrasives externally. Other configurations were the same as those in Example 1, and the same evaluation was performed. As a result, no image flow / fusion occurred and good image formation was performed.

  If the structure of a present Example is used, the application quantity of the solid lubricant 6e can be reduced rather than before by using together with a lubrication agent and an abrasive | polishing agent. As a result, the solid lubricant 6e can be reduced in size / longer life, and an image forming apparatus that can guarantee long-term cleaning performance can be provided.

  The solid lubricant 6e may be a higher fatty acid metal salt (so-called metal soap) other than zinc stearate used in this embodiment, or a solid wax mainly composed of an ester of a higher fatty acid and a higher alcohol. But it doesn't matter. In short, the same effect can be obtained if a thin film can be formed by applying a fine powder obtained by scraping the block-like solid lubricant 6e with the cleaning brush 6d.

[Example 33]
In the present embodiment, in the configuration of the above-described embodiment 32, the operation of the cleaning auxiliary member 6d is controlled according to the discharge current amount, and the supply amount of the lubricant to the surface of the photoreceptor is variable.

In this embodiment, as shown in Table 5, the controller C changes the setting of the discharge current amount according to the use environment detected by the environment detection means 52 (FIG. 9) provided in the image forming apparatus. The controller C calculates the amount of moisture in the air (stem g / mm ³ ) based on the detected environment information input from the environment detecting means 53. Environment 1 is a low-humidity environment with a moisture content of less than 5.0 g / m ³ , and in this environment, a discharge current of 100 μm is set to flow. Environment 2 has a setting in which the amount of moisture in the air is 5.0 to 20.0 g / m ³ and a discharge current of 50 μm flows under this environment. Environment 3 is a high-humidity environment where the amount of moisture in the air is greater than 20.0 g / m ³ , and in this environment, a discharge current of 20 μm is set to flow. Here, the discharge current (μA) in Tables 5 and 6 is the discharge current amount ΔIac. This discharge current amount ΔIac is determined by the environment. The values of A and B are adjusted so that the relational expression of claim 1 is established. In an environment that requires a large amount of discharge current, it is necessary to increase the amount of abrasive and lubricant supplied. By doing so, the relational expression is established. As a method for increasing the supply amount, in the case of developing supply, a measure such as blackening is applied at the time of non-image formation. In the case of supplying a solid lubricant, measures such as cleaning brush peripheral speed UP can be mentioned.

  That is, in a low-humidity environment, sand is easily generated for reasons such as increasing the resistance of the charging roller 2, and therefore, a large discharge current is set to flow. On the other hand, in the high humidity environment, the sand was hardly generated, so the discharge current was set to a small value.

  In this embodiment, as shown in Table 5, the supply amount of the lubricant onto the surface of the photoreceptor is changed according to the setting of the discharge current amount. The supply of the lubricant onto the surface of the photoconductor is configured such that zinc stearate as the solid lubricant 6e is scraped off by the cleaning brush 6d and supplied onto the surface of the photoconductor as in the case of the embodiment 32. The change in the supply amount of the lubricant was performed by changing the circumferential speed ratio of the cleaning brush 6d to the photosensitive member. That is, as the ratio of the peripheral speed of the cleaning brush 6d to the photosensitive member increases, the lubricant supply amount B increases.

  Other configurations were the same as those in Example 32, and the same evaluation was performed. As a result, no image flow / fusion occurred and good image formation was possible.

  If the configuration of this embodiment is used, the supply amount of the lubricant is controlled in accordance with the discharge current amount. Therefore, excessive supply or insufficient supply of the lubricant can be prevented, and an appropriate amount of the lubricant can be stably performed throughout.

  Further, when used in combination with an abrasive as in Example 32, the solid lubricant 6e can be reduced in size / longer life, and an image forming apparatus that can guarantee long-term cleaning performance can be provided.

[Example 34]
In this embodiment, the gap (gap) between the surface of the charging roller 2 and the photosensitive member 1 is made variable so that the gap is appropriately changed according to the use environment of the image forming apparatus. In this embodiment, as shown in FIG. 10, the charging roller 2 is arranged so as to be movable in parallel with the photoreceptor 1 by a shift mechanism 53 including a stepping motor M <b> 2. Then, the controller C controls the motor M2 via the motor driver 54, so that the charging roller 2 is in contact with the photosensitive member 1 and the predetermined interval d (charging gap: closest approach interval). It can be controlled to the state of floating in contact.

  The image forming apparatus is provided with environment detection means 52 for detecting the environment (temperature and humidity) inside the apparatus, and the detection information is input to the controller C. The controller C controls the stepping motor M2 of the shift mechanism 53 in accordance with the input detection environment information to appropriately change the interval d.

More specifically, the controller C calculates the moisture content (g / mm ³ ) in the air in which the apparatus is used based on the detected environment information input from the environment detecting means 52. Then, as shown in Table 6, the distance d between the surface of the charging roller 2 and the surface of the photosensitive member 1 is variable depending on the amount of water in the usage environment (environment 1, environment 2, environment 3).

  The reason why the distance d between the surface of the charging roller 2 and the photosensitive member 1 is increased in an environment where the amount of moisture is large is that in a humid environment, a liquid cross-linking force is generated. This is because the adhesion level with the particles such as the agent is increased and the contamination level on the surface of the charging roller is deteriorated. If the charging gap is widened, the amount of discharge current required to obtain uniform chargeability also increases, so that a large amount of lubricant is required. In this example, the lubricant application amount control was the same as that in Example 33. The rest of the configuration was the same as in Example 33, and the same evaluation was performed. As a result, no image flow / fusion occurred and good image formation was possible.

  If the configuration of this embodiment is used, contamination of the charging roller surface can be reduced in all use environments, so that good charging performance can be obtained in the long term. Furthermore, since the supply amount of the lubricant is controlled in accordance with the discharge current amount, excessive supply or supply shortage of the lubricant can be prevented, and an appropriate amount of lubricant can be stably performed throughout.

  Further, in the same manner as in Example 33, when used in combination with an abrasive, the solid lubricant 6e can be reduced in size / longer life, and an image forming apparatus that can guarantee long-term cleaning performance can be provided.

[Other matters]
1) The image forming apparatus is not limited to the electrophotographic recording system, and may be an electrostatic recording image forming apparatus. In this case, the image carrier is not a photoconductor but an electrostatic recording dielectric. After the electrostatic recording dielectric is uniformly charged to a predetermined polarity and potential by a charging member, it is selectively discharged by a discharging means such as a discharging needle array or an electron gun unit to form a latent image.

  2) The recording medium that receives the visible image from the image carrier by the developer may be an intermediate transfer member such as an intermediate transfer belt or an intermediate transfer drum.

Overall schematic diagram of image forming apparatus of embodiment Equivalent circuit between charging roller and photoconductor Illustration of discharge current Illustration of discharge current control Schematic diagram of photoconductor layer structure Schematic diagram of proximity charging device Relationship diagram between nearest charging interval and required discharge current Schematic diagram of a cleaning device provided with a non-rotating brush member as a cleaning auxiliary member Schematic diagram of a cleaning device provided with a rotating cleaning brush (brush roller) as a cleaning auxiliary member Schematic diagram of a configuration in which the interval between the charging roller and the photoconductor is changed in accordance with the environmental information detected by the environmental detection means

Explanation of symbols

  A..Image forming part, B..Document reading part, C..Controller (control means), 1..Photosensitive body (image carrier), 2..Charging roller (charging member), 3..Laser exposure means 4 .... Developing device 41 ... Developing sleeve 5 ... Transfer roller 6 ... Cleaning device 7 ... Pre-exposure lamp 12 ... Fixing device 60 ... Gap holding member

Claims (7)

A rotatable image carrier, a charging member to which an oscillating voltage is applied to charge the surface of the image carrier, and a developing means for developing a latent image formed on the image carrier as a visible image with a developer; A transfer means for transferring the visible image to a recording medium, a cleaning blade that forms a nip portion with the image carrier and scrapes off a transfer residual developer from the surface of the image carrier after the visible image transfer to the recording medium, and a control And an image forming apparatus comprising:
The surface of the image carrier is supplied with an abrasive in which the particle shape is cubic and / or rectangular parallelepiped, and the primary particles have a particle size of 30 nm to 300 nm, and a lubricant,
A supply amount of the abrasive is A (μg / cm ² ),
The supply amount of the lubricant is B (μg / cm ² ),
The amount of discharge current flowing from the charging member to the image carrier is ΔIac (mA),
The Taber wear amount of the image carrier is T (mg),
Then,
0.5 × ΔIac / T ≦ A + 10B ≦ 5 × ΔIac / T
1 ≦ A / B ≦ 20
An image forming apparatus satisfying the relationship:   The image forming apparatus according to claim 1, wherein the abrasive is an inorganic powder, and the lubricant is a fatty acid metal salt.   The image forming apparatus according to claim 1, wherein the charging member is disposed in contact with or close to a surface of the image carrier.   At least one of the abrasive and the lubricant is externally added to the developer and is supplied to the surface of the image carrier by a developing process for developing the latent image, and the image carrier rotates in a direction more than the transfer unit. 4. The image forming apparatus according to claim 1, further comprising a member that slidably rubs the surface of the image carrier in a longitudinal direction of the image carrier on the downstream side of the image carrier. 5.   A cleaning auxiliary member is disposed in contact with the image carrier upstream of the cleaning blade in the rotation direction of the image carrier, and a block body of lubricant solidified by contact with the cleaning auxiliary member is provided. The lubricant of the block body is scraped off by the cleaning auxiliary member and applied to the surface of the image carrier, whereby the lubricant is supplied to the surface of the image carrier. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The control means controls the discharge current amount and controls the operation of the cleaning auxiliary member in accordance with the controlled discharge current amount to change the supply amount of the lubricant to the surface of the image carrier. The image forming apparatus according to claim 5.   The image forming apparatus according to claim 1, wherein the control unit changes an interval between the charging member and the image carrier in accordance with environmental information detected by an environment detection unit. apparatus.