JP3559665B2 - Image forming device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
According to the present invention, a voltage is applied to a charging member, and the charged surface made of magnetic particles of the charging member is brought into contact with a charged member, which is an image carrier, to charge the surface of the charged member. The present invention relates to an image forming apparatus of a type in which image information is written by using visible light and line scanning laser light to form an image. More specifically, the present invention relates to an image forming apparatus that uses a charging device of the above-described voltage application method as a charging unit for a surface to be charged, and stably supplies good image quality under a high humidity environment for an extremely long time.
[0002]
[Prior art]
[1] Image forming apparatus
2. Description of the Related Art Image forming apparatuses are widely used, in addition to conventional so-called copying machines for copying originals, as well as computers, which have rapidly increased in demand in recent years, and printers as output means of word processors. Since such printers have been used not only for conventional office use but also for personal use, economics such as low cost and maintenance free are emphasized. Furthermore, from the viewpoint of ecology, measures to reduce the consumption of paper, such as double-sided copying and the use of recycled paper, save energy by reducing power consumption, and reduce the amount of ozone, etc., are required with the same importance as economic efficiency.
[0003]
By the way, the corona charger, which has been the mainstream of the conventional charging system, applies a high voltage of about 5 to 10 kV to a metal wire having a diameter of about 50 to 100 μm to ionize the atmosphere and impart a charge to the opposing object. In the process, the wire itself also adsorbed dirt, and required periodic cleaning and replacement. In addition, there is a problem that a large amount of ozone is generated due to corona discharge. Regarding energy saving, there is also a problem of a photoconductor heater. Recently, the surface hardness of an electrophotographic photosensitive member used has been increased in order to increase the number of printings. In addition, the surface of the photoreceptor, which is the member to be charged, is sensitive to humidity due to the influence of corona products derived from ozone generated from the charger due to repeated use, so that moisture is easily adsorbed. This causes a lateral flow of the charge on the surface of the photoreceptor, causing a deterioration in image quality called an image flow.
[0004]
In order to prevent such image deletion, heating by a heater as described in Japanese Utility Model Publication No. 1-32055, or a magnet roller and a magnetic toner as described in Japanese Patent Publication No. 2-38956 are used. A method has been used in which an image carrier (for example, the surface of a photoreceptor) which is a member to be charged is rubbed with a formed brush to remove a corona product. Further, as described in JP-A-61-100780, a method of removing corona products by rubbing the surface of a photoreceptor with an elastic roller has been used.
[0005]
The method of rubbing the surface of the photoconductor is applied to an amorphous silicon photoconductor having extremely high hardness. However, in this method, since the size of the cleaning device is large, it is difficult to reduce the size of the image forming apparatus. In addition, the constant heating method using a heater causes an increase in power consumption as described above. The capacity of such a heater is usually about 15 W to 80 W, and the impression of a large amount of power is not obtained. However, in most cases, the power is always supplied even at night, and the power consumption per day reaches 5 to 15% of the power consumption of the entire image forming apparatus.
[0006]
Also, in the external heater heating method described in JP-A-59-111179 and JP-A-62-278577, there is no disclosure as to the improvement of the image density unstable element due to the temperature fluctuation of the photoconductor. Absent.
[0007]
In addition, ozone, which is a cause of such image deletion, has a risk of causing health damage to people and organisms around the image forming apparatus. Particularly in the case of personal use, the amount of discharged ozone must be reduced as much as possible. As described above, a method for greatly reducing the amount of ozone generated at the time of charging is demanded from the economical viewpoint.
[0008]
Under such circumstances, there is a demand for a new charging member, a charging device, and a charging device and a dehumidifying device with no or reduced amount of generated ozone as an image forming device. Hereinafter, the related art regarding the charging device, the photoconductor, and the heater will be described in more detail.
[2] Charging device
Various charging devices have been proposed to solve the above problems.
[0009]
The contact charging described in JP-A-63-208878 or the like is a method in which a charging member to which a voltage is applied is brought into contact with a member to be charged, and the surface of the photosensitive member is charged to a required potential. These have the following advantages 1, 2, and 3 as compared with a corona charging device widely used as a charging unit device.
[0010]
Advantages 1. The applied voltage required to obtain a desired potential on the surface of the member to be charged can be reduced.
[0011]
Advantage 2. The amount of ozone generated during the charging process is zero to very small, and there is no need for an ozone removal filter. Therefore, the configuration of the exhaust system of the apparatus can be simplified.
[0012]
Advantages 3. There is no need to dehumidify with a heater to prevent image deletion. For this reason, power consumption such as energization at night can be significantly reduced.
[0013]
Contact charging having the above advantages is a means for charging a photoconductor, an image carrier such as a dielectric, and other charged objects in an image forming apparatus such as a copying machine, a laser beam printer, and an electrostatic recording device. As a replacement for the corona discharge device, it has attracted attention.
[0014]
Various proposals have been made for contact charging members in order to improve contact charging. For example, JP-A-59-133569 proposes a mechanism in which a contact charging member of magnetic brush-like particles made of a magnetic material and magnetic particles (or powder) contacts an image carrier and applies a charge. I have. Japanese Patent Application Laid-Open No. 57-046265 and the like propose a new method of a mechanism in which a fur brush-like contact charging member using fur made of conductive fiber contacts and charges the image carrier. ing.
[0015]
The structure of the prior art will be described with reference to FIGS.
[0016]
The photoconductor drum 202 ′, which is an image carrier, is a drum-type electrophotographic photoconductor that is driven to rotate at a predetermined peripheral speed (process speed) in a clockwise direction of an arrow X.
[0017]
The charging member 201 'includes a multipolar magnetic body 201'-2 and a magnetic brush layer 201'-1 formed on its charged surface by magnetic particles.
[0018]
The multipolar magnetic body 201'-2 is configured like a cylindrical, so-called magnet roller, and usually uses a magnetic material such as a ferrite magnet or a rubber magnet. Further, a so-called sleeve-like material having a built-in magnetic material may be used instead of the multipolar magnetic material.
[0019]
The magnetic brush layer 201'-1 is made of a magnetic iron oxide (ferrite) powder such as a Cu-Zn-Fe-O system, a magnetite powder, a material in which a magnetic material such as ferrite or magnetite is dispersed in a resin, a well-known magnetic toner. Materials are generally used.
[0020]
It is desirable that the resistance value of the charging member is appropriately selected according to the environment in which the charging member is used, high charging efficiency, the pressure resistance of the surface layer of the photoconductor, and the like.
[0021]
The charging member 201 ′ (the multipolar magnetic body 201 ′-2, the magnetic brush layer 201 ′-1) applies a DC voltage Vdc alone (or an AC voltage (Vac) thereto) by a voltage application power supply (not shown). To the power). The outer peripheral surface of the rotating photosensitive drum 202 'is uniformly charged by the charging member 201'.
[0022]
Then, the light emitted from the lamp 210 is reflected by the original 212 placed on the original platen glass 211, and is projected via the mirrors 213, 214, 215, the lens 218 of the lens unit 217, and the mirror 216. An electrostatic latent image is formed on the photosensitive drum 202 '. Alternatively, an electrostatic latent image is formed on the photosensitive drum 202 'by scanning with a laser beam printer light (not shown) whose intensity is modulated according to an image signal.
[0023]
This latent image is visualized by a developing sleeve 204 coated with a developer of an appropriate polarity, and then transferred onto the transfer material P via a transfer charging member 206 (a). The transfer residual toner is removed from the photosensitive drum by the cleaning blade 221, and the transferred image is output after being fixed by the fixing device 224. On the other hand, the electrostatic latent image remaining on the photosensitive drum 202 ′ is erased by the charge eliminating light source 209.
[3] Photoconductor
3-1 Organic photoconductor (OPC)
In recent years, various organic photoconductive materials have been developed as photoconductive materials for electrophotographic photosensitive members. In particular, a function-separated type photoconductor in which a charge generation layer and a charge transport layer are laminated has already been put to practical use and mounted on a copying machine or a laser beam printer.
[0024]
However, one of the major disadvantages of these photoconductors is that their durability is generally low. The durability includes durability in terms of electrophotographic physical properties (for example, sensitivity, residual potential, charging ability, image blur) and mechanical durability (for example, friction and scratches on the surface of the photoreceptor due to rubbing). These are all major factors that determine the life of the photoconductor.
[0025]
Among these, the durability of the electrophotographic physical properties, particularly the image blur, is caused by the deterioration of the charge transporting substance contained in the photoreceptor surface layer by the active substances such as ozone and NOx generated from the corona charger. Things are known.
[0026]
It is also known that mechanical durability is caused by physical contact of paper, a cleaning member such as a blade / roller, toner, or the like with the photosensitive layer to cause rubbing.
[0027]
In order to improve the durability of the electrophotographic physical properties, it is important to use a charge transport material that is not easily deteriorated by an active substance such as ozone and NOx. For this purpose, it is known to select a charge transporting substance having a high oxidation potential.
[0028]
In order to increase the mechanical durability, it is important to increase the lubricity of the surface to reduce friction, and to improve the surface releasability to prevent toner filming and fusing. is there. For that purpose, it is known to mix a lubricant such as fluororesin powder particles, fluorinated graphite, and polyolefin resin powder in the surface layer.
[0029]
However, when the friction becomes extremely small, a hygroscopic substance generated by an active substance such as ozone or NOx accumulates on the surface of the photoreceptor. There was a problem.
[0030]
3-2 Amorphous silicon photoconductor (a-Si)
In electrophotography, a photoconductive material for forming a photosensitive layer in a photoreceptor has a high sensitivity, a high SN ratio [photocurrent (Ip) / dark current (Id)], and an absorption suitable for the spectral characteristics of an electromagnetic wave to be irradiated. It is required to have characteristics such as having a spectrum, fast light response and a desired dark resistance value, and being harmless to a human body during use. In particular, in the case of a photoreceptor for an image forming apparatus incorporated in an image forming apparatus used in an office as an office machine, considering that a large number of copies are made over a long period of time, long-term stability of image quality and image density is considered. Is also an important point.
[0031]
Hydrogenated amorphous silicon (hereinafter referred to as “a-Si: H”) is a photoconductive material exhibiting such excellent properties. The use of this hydrogenated amorphous silicon as a photoreceptor for an image forming apparatus is described, for example, in Japanese Patent Publication No. 60-35059.
[0032]
Such a photoreceptor for an image forming apparatus generally includes a method in which a conductive support is heated to 50 ° C. to 400 ° C., and a predetermined film forming method (for example, a vacuum deposition method, a sputtering method) is formed on the conductive support. A photoconductive layer made of a-Si is formed by ion plating, thermal CVD, photo CVD, or plasma CVD. Among them, a plasma CVD method, that is, a method in which a raw material gas is decomposed by direct current, high frequency, or microwave glow discharge to form an a-Si deposited film on a support has been put to practical use.
[0033]
JP-A-54-83746 discloses an image forming method comprising a conductive support and an a-Si (hereinafter referred to as “a-Si: X”) photoconductive layer containing a halogen atom as a constituent element. A photoconductor for an apparatus has been proposed. According to the publication, a-Si contains from 1 to 40 atomic% of halogen atoms, whereby heat resistance is high, and good electrical and optical characteristics can be obtained as a photoconductive layer of a photoreceptor for an image forming apparatus. I can do it.
[0034]
Japanese Patent Application Laid-Open No. Sho 57-115556 discloses that a photoconductive member having a photoconductive layer composed of an a-Si deposited film has electrical, optical, and optical properties such as dark resistance, photosensitivity, and photoresponsiveness. Techniques for improving the use environment characteristics such as photoconductive characteristics and moisture resistance, and the stability over time are disclosed. Specifically, this technique provides a surface barrier layer made of a non-photoconductive amorphous material containing silicon atoms and carbon atoms on a photoconductive layer made of an amorphous material having silicon atoms as a host. That is.
[0035]
Further, Japanese Patent Application Laid-Open No. 60-67951 describes a technique for a photoconductor in which a light-transmitting insulating overcoat layer containing amorphous silicon, carbon, oxygen and fluorine is laminated.
[0036]
Japanese Patent Application Laid-Open No. Sho 62-168161 describes a technique in which an amorphous material containing silicon atoms, carbon atoms, and 41 to 70 atomic% of hydrogen atoms as constituent elements is used as a surface layer.
[0037]
Further, Japanese Patent Application Laid-Open No. 57-158650 discloses that the composition contains 10 to 40 atomic% of hydrogen and has an infrared absorption spectrum of 2100 cm.^-1Absorption peak of 2000cm^-1It is described that a-Si: H having an absorption coefficient ratio of 0.2 to 1.7 with respect to the absorption peak is used for the photoconductive layer. When such a material is used for the photoconductive layer, a photoconductor for an image forming apparatus having higher sensitivity and higher resistance can be obtained.
[0038]
Japanese Patent Application Laid-Open No. 60-95551 describes a technique for performing an image forming process such as charging, exposure, development and transfer while maintaining the temperature near the surface of a photoreceptor at 30 to 40 ° C. According to the technique, it is described that the image quality of the amorphous silicon photoconductor can be improved, and more specifically, the surface resistance can be reduced due to the adsorption of moisture on the surface of the photoconductor and the resulting image flow can be prevented. ing.
[0039]
These techniques have improved the electrical, optical, photoconductive, and environmental properties of the photoreceptor for an image forming apparatus, and accordingly, the image quality.
[4] Environmentally friendly heater
It is well-known that a heat source is provided on the inner surface of the photoconductor in order to prevent or remove the high humidity image flow of the photoconductor, and most commonly, a planar or rod-shaped electric heater is disposed on the inner surface of the cylindrical photoconductor. are doing.
[0040]
[Problems to be solved by the invention]
By the way, when the charging device using the magnetic particles of the voltage application type as a brush as described above is used as a charging unit of the image carrier, the following problems can be cited.
Problem 1: Charging efficiency of charging member is insufficient
This problem is particularly remarkable when the rotation speed of the photoconductor or the potential difference between the applied charging potential (hereinafter referred to as “Vp”) and the potential of the photoconductor surface before charging is large. Therefore, the magnetic particles and the like constituting the magnetic brush layer may move to the surface of the photoreceptor during rotation of the photoreceptor during a charging step or the like, and as a result, the charging efficiency is reduced and a difference in image density is observed. become.
[0041]
As a technique for securing a magnetic attraction force of a multipolar magnetic body or the like, for example, there is a technique in which the magnetic susceptibility and the particle size of magnetic particles are defined, as disclosed in Japanese Patent Application Laid-Open No. 6-1994928. As for the photoreceptor surface, for example, as disclosed in JP-A-63-254462, SnO is contained in a resin.₂  At the dispersed surface area, the SnO₂  Some of them specify the diameter and the roughness of the surface layer. However, there is no disclosure of the effective contact area between the magnetic particles and the photoreceptor, the charging efficiency and durability associated therewith, the fluidity of the magnetic particles, and the correlation between the magnetic particle diameter and the photoreceptor surface roughness.
[0042]
Further, when the contact between the magnetic particles and the photoconductor is not sufficiently ensured, there is a case where the contact becomes locally non-contact and charging failure occurs partially or in a wide range. Particularly, in an image forming apparatus using a photoconductor having a very long life, such as an amorphous silicon photoconductor, which is used at a high speed, the image quality is deteriorated due to a decrease in the magnetic particles of the charger and uneven charging, and maintenance and The charging member must be replaced. This is a problem that increases service costs and hinders maintenance-free operation.
[0043]
There is a method of increasing the diameter of the magnetic particles in order to prevent the decrease of the magnetic particles. However, a streak on an image that is generated due to poor charging of a non-contact portion between the magnetic particles and the photoconductor, a so-called “sweeping unevenness” This is undesirable from the viewpoint of image quality.
Problem 2: There are vertical stripes during durability
The following mechanism can be considered as a mechanism for generating vertical streaks (hereinafter referred to as "mottle streaks").
[0044]
Due to mechanical force (for example, frictional force due to rotation of the photoreceptor), Coulomb force (note: this is caused by the potential difference between the magnetic brush layer and the non-charged portion of the photoreceptor surface), etc. The magnetic particles move to the photoreceptor against magnetic attraction acting between the magnetic particles constituting the brush layer. Some of it is magnetically attracted to the developing device sleeve (developing sleeve). As the number of printings increases, the accumulation of the magnetic particles attracted to the developing sleeve increases, which hinders the developing material from being developed on the photoreceptor surface. As a result, mottled lines occur. Further, development and transfer on a transfer material (for example, copy paper) may cause so-called "fogging".
[0045]
JP-A-59-133569 discloses a mechanism for re-capturing the magnetic particles by providing a blade downstream of the charger in the rotation direction of the photoconductor. However, the photoreceptor surface may be polished by the magnetic particles collected in the sleeve portion, which may cause deterioration in image quality. Particularly, in the case of a photoreceptor whose surface hardness is not so high, the influence is further increased. Therefore, when designing an image forming apparatus and an electrophotographic image forming method, an improvement from a comprehensive viewpoint such as electrophotographic physical properties and mechanical durability of a photoreceptor for an image forming apparatus is made so as to solve the above problems. It was necessary to plan. Further, it is necessary to further improve the charging member, the charging device, and the image forming apparatus.
[0046]
SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus which is improved from a comprehensive viewpoint such as electrophotographic physical properties and mechanical durability.
[0047]
[Means for Solving the Problems]
The present invention has been made to achieve the above object, and a first aspect of the present invention is to form an electrostatic latent image on the surface of a previously charged member and develop the electrostatic latent image. In an image forming apparatus that forms an image by the above, the surface thereof is configured to be chargeable, and a charged body on which an electrostatic latent image is formed,
A charging member that charges the charged body by being contacted with the charged body,
The charging member has magnetic particles on its surface,
The average particle size of the magnetic particles and the surface of the charged objectRoughnessWhat is the maximum height of
0.05 ≦ Rmax / Y ≦ 0.4
However, Rmax is the surface of the member to be charged.RoughnessMaximum height of(Μm)
Y: Average particle size of magnetic particles(Μm)
The image forming apparatus is characterized by satisfying the following relationship.
[0050]
The average particle diameter Y of the magnetic particles and the surface of the member to be chargedRoughnessThe maximum height Rmax of
0.1 ≦ Rmax / Y ≦ 0.35
It is more preferable that the above relationship is satisfied.
[0051]
The charging member,Equipped with a roller that carries the magnetic particlesIs preferred.
[0052]
It is preferable that the image forming apparatus further includes a rotation drive unit that rotates the charging member during charging by the charging member.
[0053]
It is preferable to have an interval regulating unit for regulating a distance between the charging member and the member to be charged.
[0054]
It is preferable that the surface of the member to be charged includes an amorphous material containing silicon as a base material and containing at least one of a hydrogen atom and a halogen atom.
[0055]
The member to be charged is a photosensitive member on which the electrostatic latent image is formed by irradiating light, and the photosensitive member includes a conductive support, a silicon base material, and hydrogen atoms and halogen atoms. A single-crystal material containing at least one of and a photoconductive layer exhibiting photoconductivity, and a light-receiving layer formed including a surface layer having a function of retaining charges, The photoconductive layer contains 10 to 30 atomic% of hydrogen, and has a characteristic energy of an exponential function tail obtained from a sub-bandgap light absorption spectrum of 50 to 60 meV, at least in a part where light is incident, and Localized density of states is 1 × 10¹⁴~ 1 × 10¹⁶cm^-3And the surface layer has an electric resistance value of 1 × 10¹⁰~ 5 × 10^FifteenIt is preferably Ωcm.
[0056]
The member to be charged is a photosensitive member on which the electrostatic latent image is formed by irradiating light, and the photosensitive member includes a conductive support, a silicon base material, and hydrogen atoms and halogen atoms. And a non-single-crystal material containing at least one of the following, a photoconductive layer exhibiting photoconductivity, and a light receiving layer configured to include a surface layer having a function of retaining charge, And the surface layer may include amorphous carbon containing fluorine.
[0057]
The member to be charged is a photosensitive member on which the electrostatic latent image is formed by irradiating light, and the photosensitive member includes a conductive support, a silicon base material, and hydrogen atoms and halogens. A non-single-crystal material containing at least one of atoms and a photoconductive layer showing photoconductivity, and a photoreceptive layer containing a surface layer having a function of retaining charge The surface layer may have amorphous carbon to which fluorine is bonded on the outermost surface.
[0058]
The member to be charged is a photoconductor on which the electrostatic latent image is formed by being irradiated with light, and the photoconductor is configured to include a conductive support and an organic photoconductor. It may have an organic photosensitive layer and a surface layer including the charge retaining particles.
[0059]
Hereinafter, the relationship between the means of the present invention and the operation will be described.
[0060]
FirstMagneticThe ratio between the conductive particle diameter and the maximum height of the unevenness of the photoreceptor surface is specified to be 0.05 or more and 0.4 or less. ThisBandThe magnetic particles are agitated by contact with the photoreceptor in the electric member, so that charging can be made more uniform and more efficient. In addition, it is possible to prevent so-called leakage of the magnetic particles, in which the magnetic particles move to the photoreceptor, and to obtain a high-quality image for a long period of time.
[0061]
Second, as a transfer charging memberRollers that carry magnetic particlesUsed. As a result, ozone products are not generated unlike corona charging.
[0062]
Third, the main charging member is rotated or vibrated during use.
[0063]
Fourth, a mechanism for regulating the distance between the main charging member and the photoconductor is provided.
[0064]
With these third and fourth configurations, the contact width of the magnetic particles with the photoconductor, that is, the so-called nip, and the movement of the magnetic particles in the charging member are promoted, and uniform charging is performed.
[0065]
Fifth, a novel amorphous silicon-based photoconductor is used which has reduced or eliminated the change in charging ability due to temperature (hereinafter referred to as "temperature characteristics"). As a result, a stable image having no image density change can be obtained consistently from the start-up of the apparatus without the environmentally friendly heater.
[0066]
Sixth, a novel surface layer having excellent surface roughness, hardness and friction characteristics is used.
[0067]
By combining these protective layers with improved durability and a new photoreceptor with improved temperature and electrical characteristics, it is possible to eliminate nighttime electricity, save energy, and remove high-humidity image flow without impairing high image quality. It has become possible. That is, ozone products are not generated unlike corona charging, so that a drum heater or the like for countermeasures against so-called "high humidity flow" is not required.
[0068]
Seventh, a photoreceptor having at least a conductive support, an organic photosensitive layer, and a surface layer containing charge retaining particles is used.
[0069]
The operation will be described in more detail below.
[1] Charging member
1 and 2 are schematic diagrams of a charging member, a member to be charged, and an image forming apparatus according to the present invention.
[0070]
The image forming process is as described above.
[0071]
The charging member 201 includes a multipolar magnetic body 201-2 and a magnetic brush layer 201-1.
[0072]
As the multipolar magnetic body 201-2, usually, a metal such as a ferrite magnet or a magnetic body such as a plastic magnet that can have a multipolar configuration is used. The magnetic line density varies depending on many factors such as the process speed used, the limit due to the potential difference between the applied voltage and the non-charged portion, the dielectric constant and surface properties of the member to be charged, and is appropriately selected in accordance with these conditions. The magnetic field line density at the magnetic pole position measured at a distance of 1 mm from the surface of the multipolar magnetic body 201-2 is preferably 500 gauss (G) or more. More preferably, it is 1000 G or more.
[0073]
The closest gap between the photoconductor serving as an image carrier and the multipolar magnetic body 201-2 is used to stably control the contact width (hereinafter referred to as a nip) of the magnetic brush layer 201-1 in the rotation direction of the photoconductor. , Rollers (not shown), spacers, etc., need to be set at an appropriate distance by an appropriate method. The distance is preferably in the range of 50 to 2000 μm, more preferably 100 to 1000 μm. In addition, a mechanism for adjusting the nip may be provided.
[0074]
Further, the charging member 201 is rotated and moved at an appropriate relative speed with respect to the rotation direction X of the photoconductor 202. Or you may vibrate.
[0075]
Here, the charging member in the form of a roller has been described. However, the charging member may be a fixed bar magnet (hereinafter, referred to as a “fixed brush”).
[0076]
As the magnetic particles forming the magnetic brush layer 201-1, magnetic particles such as ferrite and magnetite, a well-known toner carrier, or a toner composed of a magnetic material and a resin are generally used.
[0077]
The magnetic particles generally have a particle size of 1 to 100 μm or less, preferably 10 to 50 μm, but particles having a larger particle size may be used as long as the image quality is not affected. In addition, magnetic particles having a uniform particle size may be used, or magnetic particles having different particle sizes within the above range may be mixed and used for improving the fluidity.
[0078]
The particle size of the magnetic particles and the peak of the particle size distribution were measured using a laser diffraction type particle size distribution analyzer HEROS (manufactured by JEOL Ltd.). The actual measurement was performed by dividing the range of 0.05 μm to 200 μm into 32 logarithms, and the 50% average particle size was defined as the average particle size. Alternatively, the average particle diameter of the whole may be obtained by randomly extracting 100 or more particles with an optical microscope or a scanning electron microscope and setting the maximum chord length in the horizontal direction to the value.
[0079]
As shown in FIG. 16, the resistance of the magnetic brush layer maintains good charging efficiency, while the potential decreases in the longitudinal direction of the charging member due to leak spots and minute defects on the photoreceptor surface. 1x10 for prevention³  ~ 1 × 10¹²It is preferably Ωcm. More preferably 1 × 10⁴  ~ 1 × 10⁹  Ωcm.
[0080]
In addition, the measurement of the resistance value was performed by applying a voltage of 50 to 1000 V using an MΩ tester manufactured by HIOKI (manufacturer). In this case, the contact area was measured in a state where the cylindrical metal rotating at a specified speed and the charging member to be measured were brought close to each other until a specified bite amount was reached.
[0081]
The particle size of the magnetic particles of the magnetic brush layer 201-1 is determined by a manufacturing method, a particle size separation method, or the like. In the present invention, the microscopic contact between the magnetic particles and the photoconductor is preferably determined by defining the correlation between the particle size of the magnetic particles and the surface fine roughness of the photoconductor 202, which is a charged body to be described later. To prevent deterioration in image quality due to poor charging caused by abnormal current, magnetic particle fluidity defect, and the like.
[0082]
By making the correlation between the particle size of the magnetic particles and the surface roughness of the photoreceptor in a suitable state, the contact area between the magnetic particles and the photoreceptor during passage through the charging member is increased, and magnetic particle leakage and abnormal current In addition, a charging failure can be prevented, and a high-quality image can be stably obtained. For example, in an electrophotographic apparatus having pre-exposure (especially, an electrophotographic apparatus using an amorphous silicon-based photoconductor), when a large current is being applied from the charging member to the photoconductor, several tens μA / cm²  (Several 100 μA in total current) flows. At this time, by increasing the contact area between the magnetic particles and the photoreceptor, the movement of microscopic charges becomes smooth. As a result, it is possible to prevent uneven charging and to prevent the magnetic particles from moving while the magnetic particles are still charged.
[0083]
Further, the risk of mechanical damage to the surface of the photoreceptor and the magnetic particles is reduced, which is advantageous for prolonging the life of the apparatus and maintenance-free. Further, the stirring of the magnetic particles in the charging member by the surface of the photoreceptor can be more efficiently performed, and uneven charging can be prevented.
[0084]
When a sleeve containing a magnetic material such as a magnet is used as a charging member (structurally similar to a general developing device), the surface of the sleeve is also used with an appropriate roughness for transporting the magnetic particles. This is also effective from the same operation as described above.
[0085]
Further, the service maintenance interval such as replacement and addition of magnetic particles can be extended, and maintenance free can be realized. Furthermore, it is possible to cope with a change in the setting of the image forming apparatus (for example, the setting of the process speed and the charging of the image holding member) in a wide range in terms of durability and the like.
[0086]
The photoconductor 202 to be charged may be the same as the conventional photoconductor, but a new photoconductor to be described later is used as necessary.
[2] Photoconductor
As one means for solving the above-mentioned problems, the present inventors have focused on the fine roughness of the surface of the photoreceptor, defined the fine surface roughness, and defined the correlation with the surface roughness of the magnetic particles. By doing so, it has been found that extremely suitable image stabilization can be achieved over a long period of time.
[0087]
As another means for solving the above-mentioned problem, the present inventors have used a photoreceptor having a small temperature dependency and excellent surface durability in addition to the above-described conditions, and an extremely suitable image for a long time. It has been found that stabilization is achieved. The details will be described below.
[0088]
2-1 Organic photoconductor (OPC)
An OPC photoconductor, which is one form of a preferable photoconductor used in the present invention, will be described below.
[0089]
FIG. 3F shows an example of an OPC photosensitive member for an image forming apparatus. The OPC photoreceptor 1100 has a photosensitive layer 1102 provided on a support 1101 for the photoreceptor. The photosensitive layer 1102 is provided with a charge generation layer 1107 and a charge transport layer 1108. If necessary, a protective layer or a surface layer 1104 'and an intermediate layer between the support 1101 and the charge generation layer 1107 are provided. Have been.
[0090]
The OPC photoreceptor (that is, the surface layer, the photoconductive layer, and the optional intermediate layer) used in the present invention, particularly the surface layer, efficiently receives the charge injection from the contact charging member and removes the charge. It is necessary to keep it effective. The present inventors have found that charge retention particles (for example, SnO 2₂  It has been found that materials in which metal oxides (such as, for example) are dispersed act synergistically on the properties of the respective resin components and satisfy these conditions.
[0091]
One example of the resin used for forming the surface layer, photoconductive layer, charge transport layer and charge generation layer of the electrophotographic photoreceptor of the present invention will be described. Polyester is a binding polymer of an acid component and an alcohol component, and is a polymer obtained by condensation of a dicarboxylic acid and a glycol or condensation of a compound having a hydroxy group and a carboxy group of hydroxybenzoic acid.
[0092]
As the acid component, terephthalic acid, isophthalic acid, aromatic dicarboxylic acids such as naphthalenedicarboxylic acid, succinic acid, adipic acid, aliphatic dicarboxylic acids such as sebacic acid, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, and hydroxyethoxy. An oxycarboxylic acid such as benzoic acid can be used.
[0093]
As the glycol component, ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, cyclohexane dimethylol, polyethylene glycol, polypropylene glycol and the like can be used.
[0094]
Incidentally, polyfunctional compounds such as pentaerythritol, lorimethylolpropane, pyromellitic acid and their ester-forming derivatives may be copolymerized as long as the polyester resin is substantially linear.
[0095]
As the polyester resin used in the present invention, a high melting point polyester resin is used.
[0096]
As the high melting point polyester resin, those having an intrinsic viscosity of 0.4 dl / g or more, preferably 0.5 dl / g or more, more preferably 0.65 dl / g or more in orthochlorophenol at 36 ° C. are used.
[0097]
Preferred high melting point polyester resins include polyalkylene terephthalate resins. The polyalkylene terephthalate resin mainly comprises terephthalic acid as an acid component and alkylene glycol as a glycol component.
[0098]
Specific examples thereof include polyethylene terephthalate (PET) mainly composed of a terephthalic acid component and an ethylene glycol component, and polybutylene terephthalate mainly composed of a terephthalic acid component and a 1,4-tetramethylene glycol (1,4-butylene glycol) component. (PBT), and polycyclohexyl dimethylene terephthalate (PCT) mainly composed of a terephthalic acid component and a cyclohexane dimethylol component. Other preferred high molecular weight polyester resins include polyalkylene naphthalate resins. The polyalkylene naphthalate-based resin is mainly composed of a naphthalenedicarboxylic acid component as an acid component and an alkylene glycol component as a glycol component. Phthalate (PEN) and the like can be mentioned.
[0099]
As the high melting point polyester resin, the fusion thereof is preferably 160 ° C. or higher, particularly preferably 200 ° C. or higher.
[0100]
In addition to the polyester resin, an acrylic resin may be used.
[0101]
As the binder, bifunctional acrylic, hexafunctional acrylic, phosphazene or the like is used.
[0102]
It is considered that these resins have relatively high crystallinity, and the mutual entanglement between the cured resin polymer chain and the high melting point polymer chain is uniform and dense, so that a highly durable surface layer can be formed. In the case of a low melting point polyester resin or the like, since the crystallinity is low, there are portions where the degree of entanglement with the cured resin polymer chain is large and small, and it is considered that the durability is inferior.
[0103]
For the surface layer, SnO₂  A material in which a charge holding material such as described above was dispersed was used. It is preferable to control the resistance value and the charging efficiency by appropriately changing the dispersion amount according to the use conditions and the like.
[0104]
The surface of the photoreceptor can be adjusted to have a fine surface roughness by using an abrasive having an appropriate diameter or particles having the same components as the magnetic particles of the charging member.
[0105]
2-2 Amorphous silicon photoconductor (a-Si)
An amorphous silicon-based photoconductor (hereinafter, referred to as “a-Si photoconductor”), which is one form of a preferable photoconductor used in the present invention, will be described below.
[0106]
The a-Si-based photoreceptor according to the present invention includes a well-known conductive support and a photosensitive layer having a photoconductive layer made of a non-single-crystal material having silicon atoms as a base. Although the a-Si photoreceptor may be used as it is, a material having improved characteristics as needed is used.
[0107]
In the a-Si photoreceptor having improved characteristics according to the present invention, the photoconductive layer contains 10 to 30 atomic% of hydrogen, and the characteristic energy of the exponential function (Urbuck tail) of the light absorption spectrum is 50 to 60 meV. And the local density of states is 1 × 10¹⁴~ 1 × 10¹⁶cm^-3It is characterized by being.
[0108]
The photoreceptor for an image forming apparatus designed in this way exhibits extremely excellent electrical, optical and photoconductive properties, image quality, durability and use environment properties, including the temperature dependency of the charging ability.
[0109]
Hereinafter, a photoconductor for an image forming apparatus employing the amorphous silicon photoconductor (a-Si) of the present invention will be described in detail with reference to FIG.
[0110]
In the photoconductor 1100 for an image forming apparatus shown in FIG. 3A, a photoconductive layer 1102 is provided on a support 1101 for the photoconductor. The photosensitive layer 1102 includes a photoconductive layer 1103 containing a-Si: H, X and having photoconductivity.
[0111]
In the photoconductor 1100 for an image forming apparatus shown in FIG. 3B, a photoconductive layer 1102 is provided on a support 1101 for the photoconductor. The photosensitive layer 1102 includes a photoconductive layer 1103 containing a-Si: H, X and having photoconductivity, and an amorphous silicon-based surface layer 1104.
[0112]
In the photoconductor 1100 for an image forming apparatus shown in FIG. 3C, a photoconductive layer 1102 is provided on a support 1101 for the photoconductor. The photosensitive layer 1102 includes a photoconductive layer 1103 containing a-Si: H, X and having photoconductivity, an amorphous silicon-based surface layer 1104, and an amorphous silicon-based charge injection blocking layer 1105.
[0113]
The photosensitive member 1100 for an image forming apparatus shown in FIGS. 3D and 3E has a photosensitive layer 1102 provided on a support 1101 for the photosensitive member. The photosensitive layer 1102 includes a charge generation layer 1107 containing a-Si: H, X, which constitutes the photoconductive layer 1103, a charge transport layer 1108, and an amorphous silicon-based surface layer 1104.
[0114]
Hereinafter, each part constituting the photoconductor of the amorphous silicon photoconductor (a-Si) in the present invention will be described in detail.
[0115]
2-2-1 Support
The support may be conductive or electrically insulating. Examples of the conductive support include metals such as Al, Cr, Mo, Au, In, Nb, Te, V, Ti, Pt, Pd, and Fe, and alloys thereof, such as stainless steel. In addition, at least the surface of the electrically insulating support such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polystyrene, polyamide or the like on the side on which the photosensitive layer is to be formed of an electrically insulating support such as a ceramic or the like. A support subjected to a conductive treatment can also be used.
[0116]
The support 1101 is in the form of a cylindrical or plate-like endless belt having a smooth (or uneven) surface. The thickness is appropriately determined so that the desired photoreceptor 1100 for an image forming apparatus can be formed, but is usually 10 μm or more from the viewpoint of mechanical strength in production and handling.
[0117]
In particular, when performing image recording using coherent light such as laser light, in order to more effectively eliminate image defects due to so-called interference fringe patterns appearing in a visible image, the number of photogenerated carriers is substantially reduced. Irregularities may be provided on the surface of the support 1101 to the extent that it does not exist. The irregularities provided on the surface of the support 1101 are formed by a known method described in JP-A-60-168156, JP-A-60-178457, JP-A-60-225854, JP-A-61-231561 and the like. Is done.
[0118]
Further, as still another method for more effectively eliminating image defects due to interference fringe patterns when coherent light is used, a light absorbing layer or the like is provided in the photosensitive layer 1102 (or below the photosensitive layer 1102). An interference prevention layer or region may be provided.
[0119]
The fine roughness of the surface of the photoreceptor can be controlled by making fine scratches on the surface of the support. The scratches can be formed by polishing with an abrasive, etching by a chemical reaction, so-called dry etching in plasma, sputtering, or the like. The depth and size of the flaw may be within a range in which photogenerated carriers are not substantially reduced.
[0120]
2-2-2 Photoconductive layer
The photoconductive layer 1103 constituting a part of the photosensitive layer 1102 is formed on the support 1101 (in some cases, on the undercoat layer (not shown)) by a vacuum deposition film forming method. In this case, it goes without saying that the numerical conditions of the film forming parameters are appropriately set so as to obtain the desired characteristics.
[0121]
Specifically, a glow discharge method (for example, an AC discharge CVD method such as a low-frequency CVD method, a high-frequency CVD method, or a microwave CVD method, or a DC discharge CVD method), a sputtering method, a vacuum deposition method, an ion plating method , A photo-CVD method, a thermal CVD method and the like. These thin film deposition methods are appropriately selected and employed depending on factors such as manufacturing conditions, the degree of load under capital investment, the manufacturing scale, and the characteristics required for a photoconductor for an image forming apparatus to be manufactured. In practice, a glow discharge method, in which the control of conditions is relatively easy, particularly a high-frequency glow discharge method using a power supply frequency in the RF band, μW band or VHF band is suitable.
[0122]
The formation of the photoconductive layer 1103 by the glow discharge method is basically known. That is, a source gas for supplying Si that can supply silicon atoms (Si), a source gas for supplying H that can supply hydrogen atoms (H), and / or a source gas for supplying X that can supply halogen atoms (X). The raw material gas is introduced in a desired gas state into a reaction vessel in which the inside can be reduced in pressure. Then, a layer made of a-Si: H, X is formed on the support 1101 previously set at a predetermined position by generating glow discharge in the reaction vessel.
[0123]
Further, in order to compensate for dangling bonds of silicon atoms and improve layer quality (particularly, photoconductivity and charge retention characteristics), the photoconductive layer 1103 must contain hydrogen atoms and / or halogen atoms. is necessary. The content of the hydrogen atom (or the halogen atom) or the sum of the hydrogen atom and the halogen atom is 10 to 30 atom% with respect to the sum of the silicon atom and the hydrogen atom and / or the halogen atom. Preferably, the content is 15 to 25 atomic%.
[0124]
In order to structurally introduce hydrogen atoms into the formed photoconductive layer 1103 and to easily control the introduction ratio, these gases are further added with H.₂  It is necessary to form a layer by mixing a desired amount of He or a silicon compound gas containing a hydrogen atom. Each gas may be not only a single species but also a mixture of a plurality of species at a predetermined mixture ratio.
[0125]
As the source gas for supplying a halogen atom used in the present invention, for example, a gaseous or gasifiable halogen compound such as a halogen gas, a halogen compound, an interhalogen compound containing a halogen, a silane derivative substituted with a halogen, etc. Preferred are mentioned. Further, a silicon hydride compound containing a halogen atom in a gaseous state (or capable of being gasified) containing a silicon atom and a halogen atom as constituent elements can also be used.
[0126]
Specific examples of the halogen compound that can be suitably used in the present invention include fluorine gas (F₂  ), BrF, ClF, ClF₃  , BrF₃  , BrF₅  , IF₃  , IF₇  And the like.
[0127]
Specific examples of the silicon compound containing a halogen atom, ie, a silane derivative substituted with a halogen atom, include, for example, SiF₄  , Si₂  F₆  And the like.
[0128]
In order to control the amount of hydrogen atoms and / or halogen atoms contained in the photoconductive layer 1103, for example, the temperature of the support 1101, the discharge power, and the like may be controlled. Further, the amount of the raw material used to contain a hydrogen atom and / or a halogen atom in the reaction vessel may be controlled.
[0129]
In the present invention, the photoconductive layer 1103 preferably contains atoms for controlling conductivity as necessary. The atoms controlling the conductivity may be contained in the photoconductive layer 1103 in a state of being distributed uniformly and evenly, or there may be a part contained in the layer thickness direction in a non-uniform distribution state. . As the atom for controlling the conductivity, a so-called impurity in the field of semiconductors can be cited, and an atom belonging to Group IIIb of the perimeter table giving p-type conduction characteristics (hereinafter, abbreviated as “Group IIIb atom”). ) Or an atom belonging to the group Vb of the peripheral discriminant table that gives n-type conduction characteristics (hereinafter abbreviated as “atom of group Vb”).
[0130]
Specific examples of Group IIIb atoms include boron (B), aluminum (Al), gallium (Ga), indium (In), and thallium (Tl), with B, Al, and Ga being particularly preferred. is there. Specific examples of group Vb atoms include phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi), and the like, and P and As are particularly preferable.
[0131]
The content of atoms for controlling conductivity contained in the photoconductive layer 1103 is preferably 1 × 10^{ー 2}~ 1 × 10⁴  Atomic ppm, more preferably 5 × 10^{ー 2}~ 5 × 10³  Atomic ppm, optimally 1 × 10^-1~ 1 × 10³  Desirably, it is atomic ppm.
[0132]
In order to structurally introduce an atom for controlling conductivity (for example, a group IIIb atom or a group Vb atom) contained in the photoconductive layer 1103, it is necessary to introduce a group IIIb atom during the formation of the layer. May be introduced in a gaseous state together with another gas for forming the photoconductive layer 103 into the reaction vessel.
[0133]
As the raw material for introducing Group IIIb atoms or the raw material for introducing Group Vb atoms, those which are gaseous at normal temperature and pressure or those which can be easily gasified at least under layer forming conditions are employed. Is desirable.
[0134]
As such a raw material for introducing a Group IIIb atom, specifically, for introducing a boron atom,₂  H₆  , B₄  H₁₀, B₅  H₉  , B₅  H₁₁, B₆  H₁₀, B₆  H₁₂, B₆  H₁₄Borohydride, BF₃  , BCl₃  , BBr₃  And the like. In addition, AlCl₃  , GaCl₃  , Ga (CH₃  )₃  , InCl₃  , TlCl₃  And the like.
[0135]
As a raw material for introducing a group Vb atom, for example, PH for introducing a phosphorus atom is used.₃  , P₂  H₄  Phosphorus hydride, PH₄  I, PF₃  , PF₅  , PCl₃  , PCl₅  , PBr₃  , PBr₅  , PI₃  And the like. In addition, AsH₃  , AsF₃  , AsCl₃  , AsBr₃  , AsF₅  , SbH₃  , SbF₃  , SbF₅  , SbCl₃  , SbCl₅  , BiH₃  , BiCl₃  , BiBr₃  And the like can also be mentioned as effective as starting materials for introducing Group Vb atoms.
[0136]
The raw material for introducing atoms for controlling the conductivity may be replaced with H if necessary.₂  And / or diluted with He.
[0137]
Further, in the present invention, it is also effective that the photoconductive layer 1103 contains at least one of the group consisting of carbon atoms, oxygen atoms, and nitrogen atoms. The content of these (carbon atoms, oxygen atoms, and nitrogen atoms) is preferably 1 × 10 4 based on the sum of silicon atoms, carbon atoms, oxygen atoms, and nitrogen atoms.^-5-10 atomic%, more preferably 1 × 10^-4~ 8 atomic%, optimally 1 × 10^-3-5 atomic% is desirable. These (carbon atoms, oxygen atoms, and nitrogen atoms) may be evenly and uniformly contained in the photoconductive layer, or have a non-uniform distribution such that the content changes in the thickness direction of the photoconductive layer. There may be parts.
[0138]
The layer thickness of the photoconductive layer 1103 in the present invention is appropriately determined as desired from the viewpoint of obtaining desired electrophotographic characteristics and economic effects. Preferably, it is 20 to 50 μm, more preferably 23 to 45 μm, and most preferably 25 to 40 μm.
[0139]
The optimal temperature range of the support 1101 is appropriately selected according to the layer design. In the normal case, the temperature is preferably 200 to 350 ° C, more preferably 230 to 330 ° C, and most preferably 250 to 310 ° C.
[0140]
Conditions such as the temperature of the support and the gas pressure for forming the photoconductive layer are not usually independently determined separately. Therefore, in order to form a photoreceptor having desired characteristics, it is desirable to determine an optimum value based on mutual and organic relationships.
[0141]
2-2-3 Surface layer
In the present invention, it is preferable to further form an amorphous silicon-based surface layer 1104 on the photoconductive layer 1103 formed on the support 1101 as described above. The surface layer 1104 has a free surface 1106 and is provided to achieve the object of the present invention mainly in moisture resistance, continuous repeated use characteristics, electric pressure resistance, use environment characteristics, and durability.
[0142]
The surface layer 1104 can be made of any material as long as it is an amorphous silicon-based material. For example, amorphous silicon containing a hydrogen atom (H) and / or a halogen atom (X) and further containing a carbon atom (hereinafter referred to as “a-SiC: H, X”) may be used. Amorphous silicon containing a hydrogen atom (H) and / or a halogen atom (X) and further containing an oxygen atom (hereinafter referred to as “a-SiO: H, X”) may be used. Amorphous silicon containing a hydrogen atom (H) and / or a halogen atom (X) and further containing a nitrogen atom (hereinafter referred to as “a-SiN: H, X”) may be used. Further, amorphous silicon containing a hydrogen atom (H) and / or a halogen atom (X) and further containing at least one of a carbon atom, an oxygen atom, and a nitrogen atom (hereinafter, “a-SiCON: H, X ) Are suitably used.
[0143]
The surface layer 1104 is formed by, for example, a glow discharge method (an AC discharge CVD method such as a low-frequency CVD method, a high-frequency CVD method, or a microwave CVD method, or a DC discharge CVD method), a sputtering method, a vacuum evaporation method, an ion plating method. , A known thin film deposition method such as a photo CVD method or a thermal CVD method. These thin film deposition methods are appropriately selected and employed depending on factors such as manufacturing conditions, the degree of load under capital investment, the manufacturing scale, and the characteristics desired for the photoconductor for an image forming apparatus to be manufactured. It is preferable to use the same deposition method as that for the photoconductive layer from the viewpoint of productivity.
[0144]
For example, in order to form the surface layer 1104 made of a-SiC: H, X by the glow discharge method, basically, a source gas for supplying Si capable of supplying silicon atoms (Si) and a carbon atom (C ), A source gas for supplying C that can supply hydrogen atoms (H), and / or a source gas for supplying X that can supply halogen atoms (X). Is introduced into a reaction vessel capable of reducing pressure in a desired gas state. Then, by generating a glow discharge in the reaction vessel, the surface layer 1104 made of a-SiC: H, X is formed on the support 1101 on which the photoconductive layer 1103 is provided at a predetermined position in advance. Can be formed.
[0145]
When the surface layer 1104 is composed mainly of a-SiC, the amount of carbon is preferably in the range of 30% to 90% with respect to the sum of silicon atoms and carbon atoms.
[0146]
Further, by controlling the hydrogen content in the surface layer 1104 to 30 at% to 70 at%, the electrical characteristics and the high-speed continuous usability can be dramatically improved, and a high hardness of the surface layer can be secured.
[0147]
The hydrogen content in the surface layer is H₂  It can be controlled by gas flow rate, support temperature, discharge power, gas pressure, and the like.
[0148]
In order to control the amount of hydrogen atoms and / or halogen atoms contained in the surface layer 1104, for example, the temperature of the support 1101, the discharge power, and the like may be controlled. Furthermore, the amount of the raw material used to contain hydrogen atoms and / or halogen atoms introduced into the reaction vessel may be controlled.
[0149]
Carbon atoms, oxygen atoms, and nitrogen atoms may be evenly and uniformly contained in the surface layer, or even if there is a portion having a non-uniform distribution such that the content changes in the thickness direction of the surface layer. good.
[0150]
Further, in the present invention, the surface layer 1104 preferably contains atoms for controlling conductivity as necessary. The atoms for controlling the conductivity may be contained in the surface layer 1104 in a state of being distributed uniformly and evenly, or there may be a part contained in the layer thickness direction in a non-uniform distribution state.
[0151]
As the atom for controlling conductivity contained in the surface layer 1104, a so-called impurity in the semiconductor field can be given, and a "Group IIIb atom" or a "Group Vb atom" can be used.
[0152]
If necessary, the material for introducing atoms for controlling the conductivity may be changed to H.₂  , He, Ar, Ne or the like.
[0153]
The layer thickness of the surface layer 1104 in the present invention is usually 0.01 to 3 μm, preferably 0.05 to 2 μm, and most preferably 0.1 to 1 μm. If the layer thickness is less than 0.01 μm, the surface layer 1104 is lost due to abrasion or the like during use of the photoconductor. Conversely, when the thickness exceeds 3 μm, the electrophotographic characteristics such as an increase in the residual potential are reduced.
[0154]
In order to form the surface layer 1104 having characteristics capable of achieving the object of the present invention, it is necessary to appropriately set the temperature of the support 1101 and the gas pressure in the reaction vessel as desired.
[0155]
The conditions such as the temperature of the support and the gas pressure for forming the surface layer 1104 are not usually independently determined separately, but are determined based on mutual and organic relationships to form a photoreceptor having desired characteristics. It is desirable to determine the optimal value based on this.
[0156]
Further, in the present invention, a blocking layer (lower surface layer) in which the content of carbon atoms, oxygen atoms, and nitrogen atoms is smaller than that of the surface layer 1104 may be provided between the photoconductive layer 1103 and the surface layer 1104. It is effective to further improve the characteristics such as charging ability.
[0157]
Further, between the surface layer 1104 and the photoconductive layer 1103, a region where the content of carbon atoms and / or oxygen atoms and / or nitrogen atoms changes so as to decrease toward the photoconductive layer 1103 may be provided. Thereby, the adhesion between the surface layer 1104 and the photoconductive layer 1103 can be improved, and the influence of interference due to light reflection at the interface can be further reduced.
[0158]
In addition, as the surface layer 1104, an amorphous carbon film (hereinafter, referred to as “aC: H: F”) mainly containing carbon and having a bond with fluorine inside and / or on the outermost surface is used. May be.
[0159]
aC: H: F is excellent in water repellency and low in friction, and has an effect of preventing image blurring in a high humidity environment even when the environmental countermeasure heater is removed. Further, the movement of the magnetic particles to the photoconductor due to mechanical friction can be reduced.
[0160]
2-2-4 charge injection blocking layer
In the photoreceptor for an image forming apparatus of the present invention, a charge injection blocking layer 1105 having a function of blocking charge injection from the support 1101 side between the conductive support 1101 and the photoconductive layer 1103. Is more effective. In other words, the charge injection blocking layer 1105 functions to prevent charge injection from the support 1101 side to the photoconductive layer 1103 side when the photosensitive layer 1102 has been subjected to a charging treatment of a fixed polarity on its free surface. Having. Further, such a function is not exerted when subjected to charging treatment of the opposite polarity. That is, the charge injection blocking layer 1105 has a so-called polarity dependency. In order to provide such a function, the charge injection blocking layer 1105 contains a relatively large number of atoms for controlling conductivity as compared with the photoconductive layer 1103.
[0161]
The atoms controlling the conductivity contained in the charge injection blocking layer 1105 may be distributed uniformly and uniformly in the charge injection blocking layer 1105, or may be contained evenly in the layer thickness direction. There may be a portion contained in a state of being non-uniformly distributed. When the distribution concentration is non-uniform, it is preferable that the compound be contained so as to be distributed more on the support 1101 side. In any case, it is necessary to uniformly contain the particles in a uniform distribution in a direction parallel to the surface of the support 1101 in order to make the characteristics uniform in the direction parallel to the surface.
[0162]
As the atom for controlling conductivity contained in the charge injection blocking layer 1105, a so-called impurity in the semiconductor field can be given, and a "group III atom" or a "group V atom" can be used.
[0163]
In the present invention, the thickness of the charge injection blocking layer 1105 is preferably from 0.1 to 5 μm, more preferably from 0.3 to 4 μm, from the viewpoint of obtaining desired electrophotographic characteristics and economic effects. Is preferably 0.5 to 3 μm.
[0164]
In the present invention, the above-mentioned ranges are mentioned as desirable numerical ranges of the mixing ratio of the diluent gas, the gas pressure, the discharge power, and the support temperature for forming the charge injection blocking layer 1105. However, these layer forming factors are not usually independently determined separately, but the optimum value of each layer forming factor is determined based on mutual and organic relations to form a surface layer having desired characteristics. It is desirable.
[0165]
Further, in the photoreceptor for an image forming apparatus of the present invention, for the purpose of further improving the adhesion between the support 1101 and the photoconductive layer 1103 or the charge injection blocking layer 1105, for example, Si is used.₃  N₄  , SiO₂  , SiO, or a silicon atom as a host, and an adhesion layer including an amorphous material containing a hydrogen atom and / or a halogen atom, a carbon atom and / or an oxygen atom and / or a nitrogen atom, and the like. Is also good. Further, as described above, a light absorbing layer for preventing an interference pattern from being generated by light reflected from the support 1101 may be provided.
[0166]
Each of the above-described layers (for example, a surface layer, a photoconductive layer, and a charge injection blocking layer) can be manufactured by a known apparatus and a film forming method as shown in, for example, FIGS.
[0167]
FIG. 4 shows an apparatus for manufacturing a photoconductor for an image forming apparatus by a high frequency plasma CVD method (hereinafter abbreviated as “RF-PCVD”) using an RF band as a power supply frequency.
[0168]
This apparatus is roughly provided with a deposition apparatus 3100, a source gas supply apparatus 3200, and an exhaust apparatus (not shown) for reducing the pressure inside the reaction vessel 3111.
[0169]
A cylindrical support band 3112, a heater for heating a support 3113, and a raw material gas introduction pipe 3114 are installed in a reaction vessel 3111 in the deposition apparatus 3100, and a high-frequency matching box 3115 is further connected.
[0170]
The raw material gas supply device 3200 is made of SiH₄  , GeH₄  , H₂  , CH₄  , B₂  H₆  , PH₃  And the like, gas cylinders 3221 to 226, valves 3231 to 336, 3241 to 2346, 3251 to 256, and mass flow controllers 3211 to 3216. The cylinder for each source gas is connected to a gas introduction pipe 3114 in the reaction vessel 3111 via a valve 3260.
[0171]
FIG. 5 shows an apparatus for manufacturing a photoconductor for an image forming apparatus formed by a high-frequency plasma CVD (hereinafter abbreviated as “VHF-PCVD”) method using a VHF band frequency as a power supply.
[0172]
This apparatus can be obtained by replacing the deposition apparatus 3100 in the production apparatus by RF-PCVD (see FIG. 4) with the deposition apparatus 4100 and connecting it to the source gas supply apparatus 3200. This apparatus is provided with a reaction vessel 4111 having a vacuum-tight structure, which can be reduced in pressure, a supply device 3200 for raw material gas, and an exhaust device (not shown) for reducing the pressure in the reaction vessel.
[0173]
Inside the reaction vessel 4111, a cylindrical support 4112, a heater 4113 for heating the support, a raw material gas introduction pipe 4114, and an electrode are provided, and a high frequency matching box 4120 is further connected to the electrode. The inside of the reaction vessel 4111 is connected to a diffusion pump (not shown) through an exhaust pipe 4121.
[0174]
The raw material gas supply device 3200 is made of SiH₄  , GeH₄  , H₂  , CH₄  , B₂  H₆  , PH₃  And the like, source gas cylinders 3221 to 226, valves 3231 to 2336, 3241 to 2346, 3251 to 256, and mass flow controllers 3211 to 3216. The cylinder of each source gas is connected to a gas introduction pipe 4115 in the reaction vessel 4111 via a valve 3260. The space 4114 surrounded by the cylindrical support 4112 forms a discharge space.
[0175]
By using the means and configurations described above alone or in combination, an excellent effect can be obtained.
[0176]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
[0177]
An outline of the image forming apparatus according to the present embodiment will be described with reference to FIGS.
[0178]
The photosensitive drum 202 serving as an image carrier is a drum-type electrophotographic photosensitive member that is driven to rotate at a predetermined peripheral speed (process speed) in a clockwise direction of an arrow X.
[0179]
The surface layer of the photoconductor 202 has a resistance value of 1 × in order to prevent the so-called pinhole leak, which has good electric characteristics such as charge retention ability and charging efficiency and prevents the surface layer from being damaged by voltage. 10¹⁰~ 5 × 10^FifteenIt is preferable to have a resistance of Ωcm. More preferably 1 × 10¹²~ 1 × 10¹⁴Ωcm.
[0180]
The measurement of the resistance value was performed by applying a voltage of 250 to 1 kV with an MΩ tester manufactured by HIOKI (manufacturer).
[0181]
The contact-type charging member 201 includes a multipolar magnetic body 201-2 and a magnetic brush layer 201-1 having magnetic particles formed on the surface thereof.
[0182]
The magnetic brush layer 201-1 is formed by dispersing magnetic particles in a resin such as a magnetic ferrite such as a Cu-Zn-based ferrite or a Mn-Zn-based ferrite or a magnetic magnetite or a pyrrole as described above, a carrier of a magnetic toner, or the like. Are composed of particles containing the following magnetic particles.
[0183]
As shown in FIG. 16, the resistance value of the magnetic brush layer 201-1 of the charging member 201 is 1 × 10 4 in order to maintain good charging efficiency and, on the other hand, to prevent pinholes.³  ~ 1 × 10¹²It is preferably Ωcm. More preferably 1 × 10⁴  ~ 1 × 10⁸  Ωcm. In addition, the resistance value described here was measured by applying a voltage of 250 to 1 kV with an MΩ tester manufactured by HIOKI (manufacturer).
[0184]
The charging member 201 is provided with a voltage applying unit (not shown). The DC voltage Vdc (or the voltage Vdc + Vac obtained by multiplying the AC) is applied to the magnetic brush layer 201-1 made of magnetic particles by the voltage applying means. Thereby, the outer peripheral surface of the photosensitive belt 202 being driven to rotate is uniformly charged.
[0185]
The closest gap between the photoconductor 202 and the contact charging member 201 is preferably set stably with a spacer (not shown) in the range of 50 to 2000 μm for nip control, and more preferably 100 to 1000 μm. It is. In addition, a mechanism for adjusting the nip may be provided.
[0186]
Next, the state of the contact area increase and the like in the present invention will be examined based on models and data.
[0187]
In FIG. 6, the surface roughness of the contact type charging member 201 and the surface of the photoconductor 202 and the contact state are modeled and drawn. The area where the magnetic particles of the magnetic brush layer 201-1 come into contact with the surface of the photoconductor 202 changes depending on the ratio between the particle size of the magnetic particles and the fine surface roughness of the photoconductor, as shown in the figure.
[0188]
FIG. 7 shows a correlation between X / Y (where Y: particle diameter of the magnetic particles of the charging member 201, X: twice the radius of curvature) and the contact ratio S_Touch. As can be seen from FIG. 7, good contact properties were obtained when 0.25 ≦ Y / X ≦ 4, more preferably when 0.4 ≦ Y / X ≦ 2.
[0189]
FIG. 8 shows the correlation between Rmax / Y and the fluidity. The contact ratio S_Touch conforms to B / A in FIG. The fluidity level is such that a charging member made of a multipolar magnetic material having a fixed amount of magnetic particles attached thereto is incorporated in the apparatus shown in FIGS. 1 and 2, and idles without applying a voltage and passing paper. The state of the particles was observed. From the results, the fluidity was rated as Rank 1 to Rank 5 below. The evaluation criteria for each rank are as follows: Rank 5: Very good, Rank 4: Good, Rank 3: Somewhat good, Rank 2: No practical problem, Rank 1: Some practical difficulty. As can be seen from FIG. 8, good contact properties were obtained when 0.05 ≦ Rmax / Y ≦ 0.4, more preferably when 0.1 ≦ Rmax / Y ≦ 0.35.
[0190]
9 and 10 show the ratio between the particle diameter of the magnetic particles and the fine surface roughness of the photoreceptor, and the contact area. As can be seen from FIGS. 9 and 10, by setting the surface roughness ratio in an appropriate range, a large contact area could be obtained.
[0191]
FIG. 11 shows the correlation between “the ratio of the contact area of the magnetic particles to the photoconductor with respect to the diameter of the magnetic particles” and “chargeability”. The vertical axis of the figure shows the potential immediately after the charging member in the first round when 700 Vdc is applied to the charging member. As can be seen from FIG. 11, by increasing the contact area ratio, the injection of charges is more efficiently performed, and the chargeability is improved.
[0192]
By controlling the ratio of the particle size of the magnetic particles to the ratio of the fine surface roughness of the photoreceptor to an appropriate range, the charging characteristics are improved. Further, the contact area ratio is increased, and as a result, the charging uniformity is improved. Furthermore, it can correspond to a high-definition image.
[0193]
The values of the diameter of the magnetic particles and the roughness of the photoreceptor surface are within a range that does not substantially affect the electrophotographic characteristics such as the magnetic binding force of the magnetic particles and the sensitivity characteristics of the photoreceptor. good.
[0194]
Here, the charging member 201-2 is made of a multipolar magnetic material. However, a configuration other than this drawing, such as a sleeve having a built-in magnetic material, may be used.
[0195]
【Example】
Hereinafter, the effects of the present invention will be specifically described with reference to Examples 1, 2, 3, 4, 5, 6, and 7. However, the present invention is not limited to these examples.
[Example 1] Surface roughness vs. magnetic particle diameter ratio, a, Eu of Eu-D. O. S
1. Photoconductor
1.1 Preparation of photoreceptor
An apparatus for manufacturing a photoreceptor for an image forming apparatus by an RF-PCVD method (see FIG. 4) was used. As the support, a mirror-finished aluminum cylinder having a diameter of 108 mm and an unevenness-treated cylinder having been subjected to the above-described known method were used. A photoreceptor having a charge injection blocking layer, a photoconductive layer, and a surface layer on these cylinders under the conditions shown in FIG. 12 was produced. Further, the photoconductive layer SiH₄  And H₂  Various photoreceptors were produced by changing the mixing ratio with the above and the discharge power.
[0196]
The surface roughness of the produced photoreceptor was adjusted using an abrasive such as SiC powder or diamond powder as necessary.
1.2 Characteristics of photoreceptor
The prepared photoreceptor was set in an image forming apparatus (NP6062 manufactured by Canon Inc. was modified for testing), and the temperature dependence of charging ability (temperature characteristics), memory and image defects were evaluated. In this modified machine, the transfer / separation chargers 206 (a) and 206 (b) are roller chargers or belt-shaped chargers as shown in the figure, and the generation of ozone by corona at this portion is controlled as much as possible.
[0197]
The temperature characteristics of the charging ability were measured by changing the temperature of the photoconductor from room temperature to about 45 ° C. Then, a change in charging ability per 1 ° C. of temperature was determined, and 2 V / deg or less was determined to be acceptable.
[0198]
Regarding memory and image deletion, the images were visually judged, and ranked in four stages: 1: very good, 2: good, 3: no problem in practical use, 4: slightly in practical use.
[0199]
On the other hand, an a-Si film having a thickness of about 1 μm was deposited on a glass substrate (Corning 7059) and a Si wafer placed on a cylindrical sample holder under the conditions for forming a photoconductive layer. An Al comb electrode was deposited on the deposited film on the glass substrate, and the characteristic energy (Eu) and the local density of states (DOS) of the exponential function were measured by CPM. The hydrogen content of the deposited film on the Si wafer was measured by FTIR.
[0200]
FIG. 13 shows the relationship between Eu and the temperature characteristics of the charging ability at this time. D. O. 14 and 15 show the relationship between S, the memory, and the image flow. All samples had a hydrogen content between 10 and 30 atomic%.
[0201]
As is clear from FIGS. 13, 14 and 15, the characteristic energy (Eu) of the exponential function tail obtained from the sub-bandgap optical absorption spectrum is 50 to 60 meV, and the local density of states (D. OS) is 1 × 10¹⁴~ 1 × 10¹⁶cm^-3Was found to be a suitable condition for obtaining good electrophotographic characteristics. Similarly, a sample of the surface layer was prepared, and the resistance value was measured using a comb-shaped electrode. 2. Charging member
2.1 Preparation of charging member
The contact-type charging member 101 was manufactured under the following conditions.
[0202]
The contact-type charging member 101 was configured so as to form a roller having a diameter of 22 mm with the magnetic particles adhered to the roller-shaped multipolar magnetic body. The magnetic line density is controlled as described above. In this example, the magnetic pole number was 8 poles, and the magnetic field line density on the surface of the magnetic pole portion was 1000 to 3000 Gauss by the above-described measurement.
[0203]
In this embodiment, the nip width is set to 6 to 7 mm.
[0204]
For the magnetic particles, magnetic particles composed of magnetic iron oxide were used for the magnetic brush layer for comparison of surface roughness. The magnetic particles each having a particle size of 3 to 100 μm were prepared.
3. Charging ability
The photosensitive member and the charging member produced as described above were set in an image forming apparatus (see FIGS. 1 and 2), and the charging ability was evaluated. The evaluation was performed with the environmental heater 123 turned off. The evaluation results are shown in FIG.
[0205]
As can be seen from FIG. 16, the resistance value of the charging member is 1 × 10³  ~ 1 × 10¹²In the case of Ωcm, good charging was obtained. 1 × 10⁴  ~ 1 × 10⁹  At Ωcm, better charging characteristics and environmental characteristics such as image deletion were obtained.
[0206]
The resistance value of the charging member is 1 × 10³  If it is less than Ωcm, there is a risk that abnormal discharge and pinholes will occur and the photoconductor will be damaged. Also, 1 × 10¹²In the case of Ωcm or more, the charging efficiency was lowered due to the lowering of charging efficiency and injection.
4. durability
4.1 Evaluation target
A durability test was conducted using the above-described photoconductor and magnetic particles of Example 1. FIG. 17 shows the characteristics of the photoreceptor subjected to the durability test, and FIG. 18 shows the characteristics of the magnetic particles.
[0207]
Hereinafter, the photoconductors and magnetic particles to be evaluated are distinguished by using the sample identification codes a to f of the photoconductors and the identification codes A to F of the magnetic particles used in FIGS. 17 and 18. The photoconductor of sample a shown in FIG. 17 is simply referred to as “photoconductor a”. The same applies to samples b to f. The magnetic particles of sample A shown in FIG. 18 are simply referred to as “magnetic particles A”. The same applies to samples BF.
[0208]
In the case of magnetic particles having a larger particle size than the magnetic particles shown in FIG. 18, the level of the initial image quality decreased with the particle size. Durability characteristics were in accordance with the correlation of the display.
4.2 Test method
Using an image forming apparatus (see FIGS. 1 and 2), a printing durability test of 100,000 sheets was performed in an environment of 23 ° C. and 50% RH. In the test, the heater 123 was turned off.
[0209]
A voltage obtained by multiplying a DC voltage of 600 Vdc by an AC voltage of 3 kHz and 1 kVpp was applied to the charging member 100. The magnetic brush or the charging member was rotated at a rotation speed of 60 rpm in the same direction as the photoreceptor (that is, the direction in which the advancing surfaces were in contact with the photoreceptor in opposite directions). The magnetic particles have a magnetic field line density of 2000 Gauss and a resistivity of 1 × 10⁷  ~ 1 × 10⁸  Ωcm was used. The process speed was 320 mm / sec.
[0210]
In order to be able to distinguish between the effect on the image quality due to the movement of the magnetic particles to the photoreceptor and the uneven charging of the charging member and the effect due to other factors such as the nip width, the charging member conditions such as the nip width are set. During the test, magnetic particles were appropriately replenished so as to be constant.
4.3 Evaluation method
The evaluation was made by comparing the amount of magnetic particles moved to the developing device (or copy paper where the transfer material is located) and the image quality before and after. Regarding the image quality, one of the judgments of the image quality retention rate after the test, in addition to visual judgment, is that the magnetic particles move to the developing device (or copy paper) during the test, or the fluidity of the magnetic particles is insufficient. The local density change due to local charging failure, which is considered to be due to the above, was measured. In the image density measurement, a local density change in a solid white image and a halftone image was measured by a reflection densitometer manufactured by Macbeth.
4.4 Evaluation results
FIG. 19 shows the evaluation results of the images before and after the durability test.
[0211]
As can be seen from the results of FIG. 19, when the ratio Y / X between the surface of the photoreceptor and the magnetic particle system is 0.25 or more and 4 or less, more preferably 0.4 or more and 2 or less, Mixing into the developing device and transfer to the transfer material were prevented, and good image quality was maintained. No scratches or the like were found on the surface of the photoreceptor.
[Example 2] Comparison with Rmax
A photoconductor for an image forming apparatus was manufactured under the conditions shown in FIG. The manufacturing apparatus used is the same as in Example 1 (see FIG. 4). Eu and D. of the photoconductive layer of the prepared photoreceptor were used. O. S is 55 meV, 2 × 10^Fifteencm^-3Met.
[0212]
The photoreceptor had the same value as twice the average radius of curvature of the photoreceptor c of Example 1. The maximum height Rmax of the photoreceptor surface was changed by a cylinder cutting and / or a polishing process after film formation. The characteristics of the photoconductors i to vi thus obtained are shown in FIG.
[0213]
The charging member used was the same as that in Example 1, that is, a charging member having a 2,000 Gauss mag roller and a brush layer composed of magnetic particles A to G was used.
[0214]
The application of the voltage to the charging member, the process speed, the rotation of the charging member, and the like are the same as in the first embodiment.
[0215]
The result of the same evaluation as in Example 1 is shown in FIG. When the ratio (Rmax / Y) of Rmax on the photoreceptor surface to the magnetic particle diameter Y is 0.05 or more and 0.4 or less, more preferably 0.1 or more and 0.35 or less, the magnetic particles , The rate of transfer to the developing device (or copy paper) and the occurrence of poor charging were reduced. In addition, a good image was obtained stably over a long period of time.
[Example 3] Environment dependence (H / H)
Using the photoconductor c, the magnetic particles C, the multipolar magnetic material, and the image forming apparatus used in Example 1, the same test and evaluation as in Example 1 were performed in an environment of 32.5 ° C. and 85% RH. Was.
[0216]
As a result, good images and results were obtained as in Example 1. Also, the amount of magnetic particles supplied during the test was reduced. In addition, a high-quality image was obtained stably without high-humidity image flow, mottled lines, and fogging, which are particularly concerned in a high-humidity environment. The dark state potential did not differ before and after the test.
[Example 4] Environment dependence (L / L)
Using the photoreceptor c, the magnetic particles C, the multipolar magnetic material, and the image forming apparatus used in Example 1, the same tests and evaluations as in Example 1 were performed in an environment of 15 ° C. and 10% RH.
[0217]
As a result, the initial charging efficiency was lower by 20 to 30 V than in Example 1. However, this is a value corresponding to the environmental dependence of the resistance value of the magnetic particles themselves, and the charging efficiency was equivalent under the use conditions of the particles having the same resistance value. The image was good as in Example 1. The amount of magnetic particles supplied during the test did not increase particularly.
[0218]
By the way, as an attractive force of the magnetic particles to the charging member and the recapture mechanism, a magnetic force and the like can be mentioned. On the other hand, examples of the repulsive force include an electric field based on a potential difference between the above-described member and the photoconductor, a Coulomb force, and the like. The magnetic force applied to the magnetic particles decreases according to the distance from the magnetic body surface. The Coulomb force changes according to the electric field of the charging member from the surface of the photoreceptor, but practically can be approximated to be substantially constant.
[0219]
Therefore, in the contact region (or the closest region) between the charging member (or the recapture member) and the photoconductor, the behavior of the magnetic particles between the magnetic material and the photoconductor can be approximated. In this case, depending on the magnetic line density, the potential difference between the charging member and the surface of the photoreceptor, the characteristics of the magnetic particles, etc., there are a region where the magnetic force mainly acts and a region where the Coulomb force mainly acts. , Exists.
[0220]
In particular, the a-Si type photosensitive system has a so-called "dark decay" characteristic in which the surface potential of the photoreceptor decreases after the pre-charging exposure and charging processes. Therefore, in the a-Si type photosensitive system, the voltage applied to the charging member is set higher than the voltage required at the developing position.
[0221]
Further, since the electric capacity is large, the amount of electric charge required for charging is large, and the magnetic particles easily move to the photoreceptor or the like.
[0222]
When the fluidity of the magnetic particles is insufficient, charged portions and non-charged portions are mixed on the surface of the photoreceptor. In the non-charged portion, the magnetic particles tend to move to the photoconductor side with the above capacity.
[0223]
From the above results, the ratio between the particle diameter of the magnetic particles and the radius of curvature (or the maximum height of the unevenness) of the surface of the photoreceptor is specified in an appropriate range, whereby the photoreceptor of the magnetic particles, etc. And uniform charge can be stably obtained for a long period of time.
Example 5 OPC of Charge Retaining Particle OCL
1. Photoconductor
An aluminum cylinder (outer diameter: 108 mm, length: 358 mm) was used as a substrate (support), and a 5% methanol solution of alkoxymethylated nylon was applied to the substrate by a dipping method to form an undercoat layer (intermediate layer) having a thickness of 1 μm. ).
[0224]
Next, 10 parts (parts by weight, the same applies hereinafter) of the titanyl phthalocyanine pigment, 8 parts of polyvinyl butyral, and 50 parts of cyclohexanone were mixed and dispersed for 20 hours by a sand mill using 100 parts of glass beads having a diameter of 1 mm. 70 to 120 parts (as appropriate) of methyl ethyl ketone was added to this dispersion and applied onto the undercoat layer, and dried at 100 ° C. for 5 minutes to form a 0.2 μm charge generation layer.
[0225]
Next, 10 parts of the styryl compound shown in FIG. 23 and 10 parts of bisphenol Z-type polycarbonate were dissolved in 65 parts of monochlorobenzene on the charge generation layer. This solution was applied on a substrate by dipping and dried with hot air at 120 ° C. for 60 minutes to form a 20 μm thick charge transport layer.
[0226]
Next, the surface of the charge transport layer was processed using an abrasive.
[0227]
Further, a surface layer having a thickness of 1.0 μm was provided thereon by the following method.
[0228]
High melting point polyethylene terephthalate (A) obtained using terephthalic acid as an acid component and ethylene glycol as a glycol component [intrinsic viscosity 0.70 dl / g, melting point 258 ° C (10 ° C / min using a differential calorimeter) The polyester resin to be measured was melted at 280 ° C. and quenched with ice water at 0 ° C.), and the glass point transfer temperature was 70 ° C.] and 100 parts. And 30 parts of an epoxy resin (B) [epoxy equivalent: 160; aromatic ester type; trade name: Epicoat 190P (manufactured by Yuka Shell Epoxy)] in a mixed solution of phenol and tetrachloroethane (1: 1) in 100 ml. Was.
[0229]
Furthermore, SnO as charge retaining particles in the above solution is used.₂  60 wt% of the powder was mixed. Next, 3 parts of triphenylsulfonium hexafluoroantimonate (C) was added as a photopolymerization initiator to prepare a resin composition solution.
[0230]
As the light irradiation conditions, a 2 kW high-pressure mercury lamp (30 W / cm) was irradiated at 130 ° C. for 8 seconds from a position 20 cm away from the light to cure.
[0231]
The fine roughness of the surface of the photosensitive drum thus prepared was Rmax = 3.291 μm and X = 29 μm. Here, Rmax is the maximum height of the unevenness on the surface of the photoconductor, and X is a value obtained by doubling the radius of curvature of the surface of the photoconductor.
[0232]
Using the photoconductor prepared as described above, tests and evaluations were performed as follows.
2. Test and evaluation method
A 100,000-sheet printing test was performed under the conditions of 32.5 ° C. and 85% in the same manner as in Example 3, and evaluation was made by focusing on high-humidity image deletion, mottle streaks, and fogging. Other test conditions are as follows.
[0233]
The photoreceptor is as described above. As the charging member, a charging member using a 1500 Gauss mag roller and magnetic particles B (see FIG. 18) among those shown in Example 1 was used. The nip of the charging member was set to 6 to 7 mm as in Example 1. The distance between the multipolar magnetic body and the photoconductor was 1.0 to 1.5 mm. A voltage obtained by multiplying a DC voltage of -700 Vdc by an AC voltage of 1.5 kHz and 1000 Vpp was applied to the charging member. The process speed was 200 mm / sec.
3. Evaluation results
The charging potential measured immediately after charging was -680 to -700 V both before and after endurance. The evaluation results are shown in FIG.
[0234]
Regarding the amount of scratches and abrasion on the surface of the photoreceptor after the durability test, no abrasion or abrasion that would cause a problem on the image was observed. This is because the effective contact area between the magnetic particles and the photoreceptor is widened, the charge is injected with high efficiency, and the movement of the magnetic particles is reduced, and the polishing of the photoreceptor due to the pressure of the cleaning blade is reduced. It is considered that the fluidity of the magnetic particles in the charging member was improved, and local pressure was not applied.
[Example 6] Environment dependency of use of OPC (L / L)
Using the photoreceptor, the magnetic particles, and the multipolar magnetic material used in Example 5, the same durability test and evaluation as in Example 5 were performed at 15 ° C. and 10% RH.
[0235]
The evaluation results are shown in FIG. As shown in FIG. 24, the member to be charged contains a high-melting polyester resin and a cured resin,₂  SnO in a surface layer in which charge retention particles such as₂  It has been confirmed that it is favorable conditions to have a surface layer in which the charge holding member is dispersed, such as a surface layer in which the charge holding particles are dispersed.
[0236]
The amount of scratches and abrasion on the surface of the photoreceptor after the durability test was the same as in Example 7 described later.
Example 7 a-Si drum of VHF-PCVD, aC: H: F
Using a photoconductor manufacturing apparatus for an image forming apparatus by a VHF-PCVD method (see FIG. 5), a mirror-finished aluminum cylinder (support) having a diameter of 108 mm as in Example 1, and the conditions shown in FIG. Thus, a photoreceptor comprising a charge injection blocking layer, a photoconductive layer, and a surface layer was prepared.
[0237]
Further, the photoconductive layer SiH₄  And H₂  Various photoreceptors were prepared by changing the mixing ratio with the above, discharge power, support temperature and internal pressure.
[0238]
On the other hand, under the conditions for forming the photoconductive layer, an a-Si film having a thickness of about 1 μM was deposited on a glass substrate (Corning 7059) and a Si wafer placed on a cylindrical sample holder.
[0239]
With respect to the deposited film on the glass substrate, an Al comb electrode was deposited, and the characteristic energy (Eu) and the localized level density (DOS) of the exponential function were measured by CPM. For the deposited film on the Si wafer, the hydrogen content and the Si—H₂  The absorption peak intensity ratio between the bond and the Si—H bond was measured.
[0240]
Eu, D.S. O. The relationship between S and the temperature characteristics of charging ability, memory, and image deletion was the same as in Example 1. That is, for good electrophotographic characteristics, Eu = 50-60 meV, D.E. O. S = 1 × 10¹⁴~ 1 × 10¹⁶cm^-3It has been found that the condition must be satisfied. Further, Si-H shown in FIG.₂  / Si-H and the relationship between gas and₂  / Si-H = 0.2 to 0.5 was found to be necessary.
[0241]
Eu in the photoconductor is 54 meV, and D.E. O. S is 8 × 10¹⁴cm^-3, Si-H₂  The aC: H: F surface layer was formed on the photoreceptor having a / Si-H of 0.29. Further, the photosensitive member was made to have the same surface state as the photosensitive member c of Example 2. Then, in the environment of Example 1, the same durability test and evaluation as in Example 1 were performed. In this test, magnetic particles C were used.
[0242]
The result of the durability test was good.
[0243]
Similar results were obtained when only a DC voltage was applied to the charging member in each of Examples 1 to 7 described above.
[Comparative Example 1]
4 and 5, using the same photoconductor for an image forming apparatus as in Example 2 (Eu of the photoconductive layer: 55 meV, DOS: 2 × 10^Fifteencm^-3) Was manufactured and used. The surface condition was adjusted so that Rmax = 17.52 μm and the average value of X = 67 μm.
[0244]
As the charging member, a member composed of the magnetic particles A of Example 1 and a multipolar magnetic material of 2000 Gauss was used.
[0245]
The same tests and evaluations as in Example 2 were performed. As a result, on about 100 sheets, the mixing of the magnetic particles into the sleeve of the developing device and the transfer to the copy paper started. The density difference was recognized on the image when the number of endurance sheets was 500 to 600. Further, when the cleaning blade was checked after the end of the durability test, chipping of the cleaning blade, which did not occur in the above-described example, was recognized.
[Comparative Example 2]
As the photoconductor, an organic photoconductor having the same composition as in Example 6 and a surface layer were used. Then, the surface state was made the same as that of the photoconductor of Comparative Example 1 by Al cylinder processing and polishing of the photoconductive layer. Then, a durability test and evaluation were performed in the same manner as in Example 6. In the test, the same magnetic particles as in Comparative Example 1 were used.
[0246]
As a result, streaks parallel to the rotation direction of the photoconductor occurred in the image. Polishing streaks were found on the surface of the photoreceptor at positions corresponding to the streaks on the image. Further, chipping of the cleaning blade was observed. Further, similarly to Comparative Example 1, a density difference occurred.
[0247]
【The invention's effect】
As described above, according to the present invention, the charging of the photoconductor can be made more uniform and more efficient. Further, the magnetic particles are prevented from moving to the photoreceptor, that is, so-called leakage of the magnetic particles, and a high-quality image can be obtained for a long period of time. Maintenance-free has further advanced. Furthermore, since ozone products are not generated unlike corona charging, it is also useful from an environmental point of view. In addition, energy saving can be achieved without lowering image quality (for example, high humidity image deletion). Specifically,
FirstIn, feelingThe ratio between the maximum height of the irregularities on the surface of the optical body and the diameter of the magnetic particles is specified to be 0.05 or more and 0.4 or less. ThisBandThe magnetic particles are agitated by contact with the photoreceptor in the electric member, so that charging can be made more uniform and more efficient. In addition, it is possible to prevent so-called leakage of the magnetic particles, in which the magnetic particles move to the photoreceptor, and to obtain a high-quality image for a long period of time.
[0248]
Second, a roller or a belt is used as the transfer charging member. As a result, ozone products are not generated unlike corona charging.
[0249]
Third, the main charging member is rotated or vibrated during use. Fourth, a mechanism for regulating the distance between the main charging member and the photoconductor is provided. According to the third and fourth configurations, the contact width of the magnetic particles with the photoconductor, that is, the so-called nip, and the movement of the magnetic particles in the charging member are promoted, and uniform charging is performed.
[0250]
Fifth, by combining a protective layer with improved durability and a new photoreceptor with further improved temperature characteristics and electrical characteristics, there is no power supply at night, energy saving and high image quality retention while maintaining high image quality. Removal is possible.
[0251]
Sixth, a photoreceptor having at least a conductive support, an organic photosensitive layer, and a surface layer containing charge retaining particles is used.
[0252]
As a result, a high-quality image can be stably obtained for a long period of time, and the deterioration of the image quality due to the magnetic particles being developed and being mixed in the developing device to prevent the normal toner development is prevented, and the maintenance is free. Went further.
[0253]
Further, the a-Si-based photoreceptor has to be set at a higher charging voltage especially when it has a mechanism for removing charges by main discharging light or the like before charging, and has a large capacity as compared with the organic photoreceptor. Although the current is used, it is considered that a large effect is apparent due to the above configuration alone or multiplied. In the s-Si photoreceptor having a high surface hardness and a long life, the action works more effectively.
[0254]
In addition, the printing life of the magnetic particles is extended, and the supply of the magnetic particles, that is, the service maintenance can be simplified.
[0255]
Image defects caused by protrusions on the photoreceptor or the growth of the defects were reduced. It is considered that by improving the fluidity and the like of the magnetic particles and the photoreceptor, fine abnormal discharge and the like are prevented, so that uniform charging is achieved, damage of a defective portion is prevented, and growth of an image defect is suppressed.
[0256]
Further, when the diameter of the toner was changed, the toner adhering to the photoreceptor was hardly peeled off, and "fusing" that caused a black streak-like defect in the image was suppressed. It is considered that the cleaning effect is caused by the charging member rubbing the photoconductor uniformly and closely.
[0257]
Furthermore, the level of contamination of the magnetic particles during prolonged use has been improved. It is thought that even if paper dust etc. in the device is mixed into the charging member, it will be easily released from the charging member in a small amount due to the fluidity of the magnetic particles, etc., and it will be removed outside the system early by a downstream cleaner etc. Can be This effect further improved the printing life of the magnetic particles.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a charging member, a charging device, and an image forming apparatus according to the present invention.
FIG. 2 is a schematic configuration diagram illustrating a configuration of an example of another embodiment of a charging member, a charging device, and an image forming apparatus of the present invention.
FIG. 3 is a schematic layer configuration diagram showing a layer configuration of a photoreceptor for an image forming apparatus of the present invention.
FIG. 4 is a schematic view showing a manufacturing apparatus for forming a light receiving layer of a photoreceptor for an image forming apparatus by a glow discharge method using a high frequency in an RF band.
FIG. 5 is a schematic view showing a manufacturing apparatus for forming a light receiving layer of a photoconductor for an image forming apparatus by a glow discharge method using a high frequency in a VHF band.
FIG. 6 is a schematic diagram showing a state of contact between the magnetic particles of the present invention and the surface of a photoreceptor.
FIG. 7 is a graph showing the contact ratio with respect to the ratio of the particle diameter of the magnetic particles of the present invention to twice the radius of curvature of the photoreceptor surface.
FIG. 8 is a graph showing the fluidity with respect to the ratio of the particle diameter of the magnetic particles of the present invention to twice the radius of curvature of the photoreceptor surface.
FIG. 9 is a graph showing the ratio of the contact area of the magnetic particles of the present invention and the contact property of the photoreceptor.
FIG. 10 is a graph showing the ratio of the contact area of the magnetic particles of the present invention and the contact property of the photosensitive member.
FIG. 11 is a graph showing the contact property and charging efficiency between the magnetic particles of the present invention and a photoreceptor.
FIG. 12 is a diagram showing conditions for forming a photoconductor in Example 1.
FIG. 13 is a diagram showing the relationship between the characteristic energy (Eu) of the Urbach tail of the photoconductive layer and the temperature characteristic in the photoreceptor for an image forming apparatus of the present invention.
FIG. 14 is a view showing the relationship between the local density of state (DOS) of the photoconductive layer and the optical memory in the photoreceptor for an image forming apparatus of the present invention.
FIG. 15 is a diagram showing the relationship between the local density of state (DOS) of the photoconductive layer and the image deletion in the photoreceptor for an image forming apparatus of the present invention.
FIG. 16 is a diagram showing the relationship between the resistance value and the charging efficiency of the charging member of the present invention.
FIG. 17 is a diagram illustrating characteristics of a photoconductor subjected to a durability test in Example 1.
FIG. 18 is a diagram showing characteristics of magnetic particles subjected to a durability test in Example 1.
FIG. 19 is a diagram showing evaluation results of durability in Example 1.
FIG. 20 is a diagram showing photoconductor preparation conditions in Example 2.
FIG. 21 is a diagram illustrating characteristics of a photoconductor in Example 2.
FIG. 22 is a diagram showing evaluation results in Example 2.
FIG. 23 is a view showing a styryl compound used in Example 5.
FIG. 24 is a diagram showing evaluation results in Examples 5 and 6.
FIG. 25 is a diagram illustrating conditions for forming a photoconductor in Example 7.
FIG. 26 is a view showing the relationship between the absorption peak intensity ratio of the Si—H 2 bond and the Si—H bond of the photoconductive layer and the halftone density unevenness (roughness) in the photoconductor for an image forming apparatus of the present invention.
FIG. 27 is a diagram showing a configuration of a conventional device.
FIG. 28 is a diagram showing a configuration of a conventional device.
[Explanation of symbols]
201 Charging member
201-1 Magnetic brush (magnetic particle) layer
201-2 Multipole magnetic material
202 Charged object (photoreceptor)
203 image signal applying means
204 developing sleeve
205 Paper feed system
206 (a) Transfer charger
221 Cleaning blade
223 Environmental heater
1100 Photoconductor
1101 Support
1102 Photosensitive layer
1103 Photoconductive layer
1104, 1104 'surface layer
1105 Charge injection blocking layer
1106 Free surface
1107 Charge generation layer
1108 Charge transport layer
P transfer material

Claims (10)

An image forming apparatus that forms an electrostatic latent image on a surface of a previously charged member to form an image by developing the electrostatic latent image,
An object to be charged, the surface of which is configured to be chargeable, and an electrostatic latent image formed on the surface;
A charging member that charges the charged body by being contacted with the charged body,
The charging member has magnetic particles on its surface,
The average particle size of the magnetic particles, the maximum height of the surface roughness of the charged body,
0.05 ≦ Rmax / Y ≦ 0.4
Here, Rmax is the maximum height of the surface roughness of the member to be charged (μm).
Y: average particle size of magnetic particles (μm)
Satisfies the relationship of
An image forming apparatus comprising: The average particle size of the magnetic particles, the maximum height of the surface roughness of the charged body,
0.1 ≦ Rmax / Y ≦ 0.35
Here, Rmax is the maximum height of the surface roughness of the member to be charged (μm).
Y: average particle size of magnetic particles (μm)
Satisfies the relationship of
The image forming apparatus according to claim 1, wherein: The charging member includes a roller that carries the magnetic particles,
The image forming apparatus according to claim 1, wherein: During charging by the charging member, further comprising a rotation drive unit for rotating the charging member,
The image forming apparatus according to claim 3, wherein: The charging member, having an interval regulating means for regulating the distance between the object to be charged,
The image forming apparatus according to any one of claims 1 to 4, wherein: The object to be charged, the surface of which is configured to include an amorphous material containing at least one of a hydrogen atom and a halogen atom using silicon as a base material,
The image forming apparatus according to claim 1, wherein: The member to be charged is a photoconductor on which the electrostatic latent image is formed by being irradiated with light,
The photoconductor,
A conductive support,
A photoconductive layer showing photoconductivity, comprising a non-single-crystal material containing at least one of a hydrogen atom and a halogen atom with silicon as a base material,
Having a light receiving layer configured to include a surface layer having a function of retaining charges,
The photoconductive layer contains 10 to 30 atomic% of hydrogen, and has a characteristic energy of an exponential function tail obtained from a sub-bandgap light absorption spectrum of 50 to 60 meV and a localized state at least in a part where light is incident. The density is 1 × 10 ¹⁴ to 1 × 10 ¹⁶ cm ⁻³ ,
The surface layer has an electric resistance value of 1 × 10 ^{10 to} 5 × 10 ¹⁵ Ωcm.
The image forming apparatus according to claim 6, wherein: The member to be charged is a photoconductor on which the electrostatic latent image is formed by being irradiated with light,
The photoconductor,
A conductive support,
A photoconductive layer showing photoconductivity, comprising a non-single-crystal material containing at least one of a hydrogen atom and a halogen atom with silicon as a base material,
Having a light receiving layer configured to include a surface layer having a function of retaining charges,
The surface layer is configured to include amorphous carbon containing fluorine,
The image forming apparatus according to claim 6, wherein: The member to be charged is a photoconductor on which the electrostatic latent image is formed by being irradiated with light,
The photoconductor,
A support having conductivity,
A photoconductive layer showing photoconductivity, comprising a non-single-crystal material containing at least one of a hydrogen atom and a halogen atom with silicon as a base material,
Having a light receiving layer configured to include a surface layer having a function of retaining charges,
The surface layer has amorphous carbon bonded with fluorine on its outermost surface,
The image forming apparatus according to any one of claims 6 to 8, wherein: The member to be charged is a photoconductor on which the electrostatic latent image is formed by being irradiated with light,
The photoconductor,
A conductive support,
An organic photosensitive layer comprising an organic photoconductor,
And a surface layer configured to include the charge retention particles,
The image forming apparatus according to claim 1, wherein:

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