JP2002244412A - Method and device for electrifying magnetic brush - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the reduction in the number of magnetic particles of a magnetic brush electrifying member, to maintain the initial electrifying performance and to prevent the generation of defects such as a longitudinal stripe and fogging. SOLUTION: The magnetic particles of magnetic brush electrifying member and a photosensitive body are brought into contact with each other and an electrifying bias is applied to the member so that the body is electrified through the particles. As the bias to be applied to the member, a DC voltage and an AC voltage having a peak voltage corresponding to the DC voltage are applied. To be specific, an AC voltage having a peak voltage which is equal to the absolute value of a DC voltage Vdc plus 50 V is applied. Thus, the amount of magnetic particles that are breakaway/adhered to the body is reduced and the occurrence of the reduction in the magnetic particles of the member is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic brush charging method and a magnetic brush charging device for charging an object to be charged.

[0002]

2. Description of the Related Art In recent years, in an image forming apparatus such as a printer or a copying machine, a charging device for uniformly charging an image carrier (a member to be charged) such as a photosensitive drum has advantages such as low ozone and low power. As a contact charging device, a contact charging device for charging an image carrier by bringing a charging member to which a voltage is applied into contact with the image carrier has been put to practical use.

In such a contact charging device, a charging member to be brought into contact with the image carrier is a roller type (charging roller),
There are various forms such as a blade type (charging blade) and various improvement proposals. Among them, JP-A-59-13
As disclosed in Japanese Patent No. 3569 and the like, a magnetic brush charging system using a magnetic brush-like contact charging member made of a magnetic material (magnet) and magnetic particles (or powder) has been proposed. When using the shape of the roller, than when using the roller type, blade type, etc.
It is possible to improve characteristics such as the contact property of the contact charging member with the image carrier.

FIG. 3 is a schematic diagram showing a schematic configuration of the magnetic brush charging device 3.

In FIG. 1, a magnetic brush charging device 3 comprises:
A magnetic brush charging member 30 and a charging bias application power source S1 for applying a charging bias thereto are provided. The magnetic brush charging member 30 is a sleeve rotating type device, and includes a core metal 31 and a magnet roller 3 as a cylindrical multipolar magnetic body provided concentrically and integrally around the core metal 31.
2, a non-magnetic charging sleeve 33 provided rotatably and concentrically around the cored bar 31 outside the magnet roller 32, and a magnet roller inside the charging sleeve on the outer peripheral surface of the charging sleeve 33. And a magnetic brush layer 34 formed by adsorbing and holding magnetic particles by a magnetic force of 32. This magnetic brush charging member 30
Are arranged substantially parallel to a photoreceptor (image carrier) 1 as a member to be charged, bearing both ends of a cored bar 31,
4 is arranged in contact with the surface of the photoconductor 1 so as to form a charging nip n having a predetermined width.

The magnetic brush charging member 30 rotates clockwise (in the direction of arrow R3) opposite to the rotation direction (direction of arrow R1) of the photoconductor 1 in the charging nip portion n (in the direction of arrow R3), or in the charging nip portion n. In this case, the photosensitive member 1 is rotated counterclockwise, which is the forward direction of the rotating direction of the photosensitive member 1, and the surface of the photosensitive member 1 is rubbed by the magnetic brush layer 34 at the charging nip n.

Then, a predetermined charging bias is applied to the magnetic brush layer 34 via the charging sleeve 33 by the charging bias applying power source S1 to apply a DC voltage (Vdc) having a predetermined polarity and potential.
The surface (outer peripheral surface) of the photoreceptor 1 which is applied by a vibration voltage (Vdc + Vac: AC application method) in which an AC voltage Vac is superimposed and which is rotationally driven is applied with a predetermined polarity by a contact charging method. -Uniformly charged to potential.

Here, the magnet roller 32 is usually
Magnetic materials such as ferrite magnets and rubber magnets are used.

The magnetic particles forming the magnetic brush layer 34 include a magnetic iron oxide (ferrite) powder such as a Cu—Zn—Fe—O system, a magnetite powder, and a magnetic material such as a ferrite or a magnetite dispersed in a resin. A well-known magnetic toner material or the like is generally used.

When this magnetic brush charging method is used, a member having a surface layer in which conductive fine particles are dispersed on an organic photosensitive member (OPC) or an amorphous silicon-based photosensitive member (a-Si) is used as a member to be charged. Since a charging potential substantially equal to the DC component (Vdc) of the charging bias applied to the contact charging member 30 can be obtained on the surface of the member to be charged, such a charging method is referred to as injection charging. .

Furthermore, if this injection charging is used, since a discharge phenomenon in which a charged object is charged using a corona charger is not used, complete ozone-free and low power consumption type charging is possible, which has attracted attention. Is coming.

[0012]

However, in the image forming apparatus, when the above-described magnetic brush charging system is used as a charging unit of the photosensitive member 1 as a member to be charged, there are the following problems.

When the rotational speed difference between the photosensitive member 1 and the magnetic brush charging member 30 is large, or when the applied charging bias is large and the potential difference between the charged photosensitive member surface potential and the non-charged portion is large, the magnetic brush charging member 30 This is a problem that the durability of the resin becomes insufficient.

That is, the magnetic particles constituting the magnetic brush layer 34 gradually separate from the magnetic brush layer 34 during the rotation of the photoreceptor 1 during a charging step and adhere to the surface of the photoreceptor, and are carried away. As a result, the magnetic particles of the magnetic brush layer 34 decrease, the magnetic brush layer 34 becomes thinner, and the charging nip n
Will be narrower.

The phenomenon of detachment and adhesion of the magnetic particles constituting the magnetic brush layer 34 to the surface of the photoreceptor is caused by the magnetic brush layer 34.
In response to the magnetic attraction force of the magnetic particles constituting the magnetic sleeve toward the charging sleeve 33, mechanical force such as friction caused by rotation of the photoconductor 1 and the magnetic brush charging member 30, the charging of the magnetic brush layer 34 and the photoconductor 1 It is generated by overcoming a Coulomb force or the like generated by a later surface potential or a potential difference from an uncharged portion. As a result,
As the durability of the magnetic brush layer 34 decreases, the magnetic brush layer 34 becomes thinner, the magnetic brush layer 34 becomes thinner, the width of the charging nip n becomes narrower, the charging efficiency decreases, and a density difference appears in the image. Become.

In the case where an amorphous silicon photoconductor (a-Si) is used as the photoconductor 1, there is provided a mechanism for performing static elimination by static elimination light using a pre-exposure lamp 8 (see FIG. 2) or the like before charging. In this case, since the surface potential of the photoconductor 1 is attenuated after charging, that is, there is a so-called “dark decay”, this phenomenon becomes more remarkable.

FIG. 4 shows that the magnetic brush charging device 3 is an organic photoconductor (OPC) or an amorphous silicon photoconductor (a-S
FIG. 6 is a potential diagram showing charging performance when used in i).

In FIG. 1, a DC voltage (Vdc) applied to the magnetic brush charging member 30 and an oscillating voltage (Vdc + V) are applied.
ac), the charging potential of the organic photoconductor (OPC) is good, but the amorphous silicon photoconductor (a-S
i) has poor followability as the charging potential, and in the case of an oscillating voltage, the potential difference from the charging potential increases as the applied DC voltage component (Vdc) increases. Here, the oscillating voltage (Vdc + Vac) is a variable DC voltage (Vdc) and the AC voltage (Vac) is fixed (500 Vpp).

On the other hand, the DC voltage (V
It is considered that the higher the value of dc), the more easily the detachment / adhesion phenomenon of the magnetic particles to the photoconductor 1 occurs. However, when the vibration voltage (Vdc + Vac) is applied to the amorphous silicon photoconductor (a-Si), A different phenomenon occurs.

FIG. 5 is a diagram showing the amount of magnetic particles detached from and adhered to the photosensitive member 1 from the magnetic brush layer 34 when the idle rotation is performed for a predetermined time.

In FIG. 1, a DC voltage (Vdc) applied to the magnetic brush charging member 30 and an oscillating voltage (Vdc + V
The amount of magnetic particles detached and attached to the organic photoconductor (OPC) for ac) and the amount of magnetic particles detached and attached to the amorphous silicon-based photoconductor (a-Si) for DC voltage (Vdc) are the same as described above. However, the amount of magnetic particles detached and attached to the amorphous silicon-based photoconductor (a-Si) with respect to the oscillation voltage (Vdc + Vac), as shown in FIG. It has occurred. Here, the oscillating voltage (Vdc + Vac) is a variable DC voltage (Vdc) while the AC voltage (Vac) is fixed (500 Vpp).

In addition, there is a problem of generation of vertical stripes at the time of durability due to the above-mentioned problems. The following is considered as a mechanism of generating vertical stripes.

That is, as described above, the magnetic brush layer 3
The magnetic particles detached from and adhered to the photoconductor 1 side from the photoconductor 4 are conveyed to the developing device 4 (see FIG. 2) as the photoconductor 1 rotates.
A part thereof is magnetically attracted to a developing sleeve 41 as a developing member of the developing device 3. Then, as the number of printing presses increases, the accumulation of magnetic particles attracted to the developing sleeve 41 increases, which hinders the development, and the developing sleeve 41 is recharged in the developing unit similarly to the charging sleeve 33. This is performed to disturb the electrostatic latent image and generate vertical stripes.

Further, the magnetic particles are developed and transferred onto a copy sheet where the recording material P is the recording material P, and so-called "fogging" may occur.

The present invention has been made in view of the above circumstances, and prevents the reduction of magnetic particles of a magnetic brush charging member, maintains initial charging performance, and prevents defects such as vertical stripes and fogging. It is an object of the present invention to provide a magnetic brush charging method and a charging device that can perform the charging.

[0026]

According to the first aspect of the present invention, there is provided a magnetic brush charging member in which magnetic particles are held on the surface of a magnetic particle carrier by a magnetic field generating means. A magnetic brush charging method for applying a charging bias to the magnetic brush charging member by bringing the magnetic particles into contact with a member to be charged, and charging the member to be charged via the magnetic particles; As a charging bias, a DC voltage and an AC voltage having a peak voltage changed according to the magnitude of the DC voltage are applied.
It is characterized by the following.

According to a second aspect of the present invention, in the magnetic brush charging method according to the first aspect, the magnetic field generating means includes:
It has a plurality of magnetic poles in the circumferential direction.

According to a third aspect of the present invention, there is provided the first or second aspect.
5. The method of charging a magnetic brush according to item 1, wherein the member to be charged is an amorphous silicon photosensitive member.

According to a fourth aspect of the present invention, there is provided a magnetic particle carrier, a magnetic field generating means disposed inside the magnetic particle carrier, and a magnetic field generating means provided on the surface of the magnetic particle carrier by the magnetic field generating means. A magnetic brush charging member having magnetic particles that are in contact with the member to be charged, and charging bias applying means for applying a charging bias to the magnetic brush charging member and charging the member to be charged via the magnetic particles. In the provided magnetic brush charging device, the charging bias applying means includes, as a charging bias applied to the magnetic brush charging member, a DC voltage and an AC voltage having a peak voltage changed according to the magnitude of the DC voltage. Applying.

According to a fifth aspect of the present invention, in the magnetic brush charging device according to the fourth aspect, the magnetic field generating means includes:
It has a plurality of magnetic poles in the circumferential direction.

The present invention according to claim 6 is directed to claim 4 or 5.
Wherein the charged object is an amorphous silicon photoreceptor.

[0032]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 Hereinafter, a case where the present invention is applied to an electrophotographic image forming apparatus will be described in detail.

First, the photosensitive member used in this embodiment will be described.

In the magnetic brush charging method, a commonly used organic photoreceptor (OPC) or the like can be used as a member to be charged. Preferably, the resistance is 10 ⁹ to 10 ¹⁴ on the organic photoreceptor. When a material having a surface layer having a material of Ω · cm or an amorphous silicon photoconductor is used, charge injection charging can be realized, which is effective in preventing ozone generation and reducing power consumption. Further, the chargeability can be improved.

(A) Organic photoreceptor (OPC) Charging sleeve 33 as a magnetic particle carrier (see FIG. 3)
As the constitution of the photosensitive layer of the laminated photoreceptor, a charge generation layer and a charge transport layer are laminated on a conductive support in this order. The conductive support may be any one as long as it has conductivity, for example, aluminum, copper, chromium, nickel, zinc and a metal such as stainless steel formed into a drum or sheet shape, such as aluminum and copper. Metal foil laminated on plastic film, aluminum, indium oxide, tin oxide, etc. deposited on plastic film, metal, plastic film or paper with conductive layer applied by applying a conductive substance alone or with binder resin Is mentioned.

As a method for applying the photosensitive layer formed on these conductive supports, methods such as spray coating, beam coating, and dip coating are used. At that time, it is usually necessary to fix and support the conductive support, and in order to keep the coating liquid from adhering to the support member, an uncoated region remains at the end of the support. There is. In addition, when the coating is applied to the end, the coating liquid may be dripped to the edge. A flange, which is an end support member to be mounted on the photoconductor to support the photoconductor in the image forming apparatus main body, is mounted at a correct angle, and polishing of the end of the conductive support member is required to maintain alignment accuracy of the photoconductor. Since a process is required, it is desirable to allow the uncoated area as much as possible in the production of the photoconductor.

In the present embodiment, the following five layers (first to fifth layers) are formed from below (from the side of the drum substrate) on a 30 mm-diameter aluminum drum substrate made of a negatively charged organic photoreceptor. The photosensitive drums provided in order were used.

The first layer is a subbing layer, and is a conductive layer having a thickness of 20 μm provided for smoothing out defects or the like of an aluminum substrate (hereinafter simply referred to as “aluminum substrate”).

The second layer is a positive charge injection preventing layer, which serves to prevent positive charges injected from the aluminum substrate from canceling out negative charges charged on the surface of the photoreceptor, and comprises an amylan resin and methoxymethylated nylon. 1 × 10 ⁶ Ω
This is a medium-resistance layer having a thickness of 1 μm and a resistance adjusted to about cm.

The third layer is a charge generation layer, and is a layer having a thickness of about 0.3 μm in which a disazo pigment is dispersed in a resin.
Exposure generates positive and negative charge pairs.

The fourth layer is a charge transport layer, in which hydrazone is dispersed in a polycarbonate resin, and is a P-type semiconductor. Therefore, negative charges charged on the surface of the photoreceptor cannot move through this layer, and only positive charges generated in the charge generation layer can be transported to the surface of the photoreceptor.

The fifth layer is a charge injection layer, which is a coating layer of a material in which ultrafine SnO ₂ particles are dispersed in a binder of an insulating resin. Specifically, SnO ₂ particles having a particle diameter of about 0.03 μm, obtained by doping an insulating resin with antimony, which is a light-transmitting insulating filler, to reduce the resistance (conducting conductivity), are dispersed in the resin by 70% by weight. This is the coating layer of the material. The thus prepared coating liquid was applied to a thickness of about 4 μm by dipping coating to form a charge injection layer. On this occasion,
There was a 5 mm uncoated area of the photosensitive layer at the back end of the photoreceptor.

(B) Amorphous silicon-based photoconductor (a
-Si) In electrophotography, a photoconductive material forming a photosensitive layer in a photoreceptor has a high sensitivity and an SN ratio (photocurrent (Ip)
/ Dark current (Id)), having an absorption spectrum suitable for the spectral characteristics of the irradiating electromagnetic wave, fast light response, having a desired dark resistance value, and harmless to the human body during use. Characteristics are required. Particularly, in the case of a photoconductor for an image forming apparatus incorporated in an image forming apparatus used in an office as an office machine, considering that the photoconductor is used in a large amount and for a long period of time, image quality and image density are stable over a long period of time. Sex is also an important point.

Hydrogenated amorphous silicon (hereinafter referred to as “a-Si:
H ". ), For example, Japanese Patent Publication No. 60-3505.
No. 9 discloses an application as a photosensitive member for an image forming apparatus.

In general, such a photosensitive member for an image forming apparatus is prepared by heating a conductive support to 50 to 400 ° C. and depositing the conductive support on the conductive support by a vacuum deposition method, a sputtering method, an ion plating method, or the like. A photoconductive layer made of a-Si is formed by a film forming method such as a CVD method, a thermal CVD method, a photo CVD method, and a plasma CVD method. Among them, the plasma CVD method, that is,
A method in which a source gas is decomposed by direct current, high frequency or microwave glow discharge to form an a-Si deposited film on a conductive support has been put to practical use as a suitable method.

In Japanese Patent Application Laid-Open No. 54-83746, an image 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 photoreceptor for a forming apparatus has been proposed. In this publication, one halogen atom is added to a-Si.
By containing 40 to 40 atomic%, heat resistance is high and good electrical and optical characteristics can be obtained as a photoconductive layer of a photoconductor for an image forming apparatus.

Japanese Unexamined Patent Publication No. 57-115556 discloses that a photoconductive member having a photoconductive layer composed of an a-Si deposited film has an electrical property such as a dark resistance value, a photosensitivity, and a photoresponsiveness. In order to improve the use environment characteristics such as optical and photoconductive properties and moisture resistance, and the stability over time, silicon atoms and carbon atoms are deposited on a photoconductive layer composed of an amorphous material based on silicon atoms. A technique of providing a surface barrier layer made of a non-photoconductive amorphous material containing atoms is described.

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. JP-A-62-1681
No. 61 describes a technique of using, as a surface layer, an amorphous material containing silicon atoms, carbon atoms, and 41 to 70 atomic% of hydrogen atoms as constituent elements.

[0050] Furthermore, in JP-A-57-158650, hydrogen containing 10 to 40 atomic%, the absorption coefficient ratio of the absorption peak of 2100 cm ^-1 and 2000 cm ^-1 in the infrared absorption spectrum 0.2 A-Si that is ~ 1.7:
It is described that by using H for a photoconductive layer, a photosensitive member for an image forming apparatus having high sensitivity and high resistance can be obtained.

On the other hand, Japanese Patent Application Laid-Open No. Sho 60-95551 discloses that in order to improve the image quality of an amorphous silicon photoreceptor, the temperature near the surface of the photoreceptor is maintained at 30 to 40.degree. A technique is disclosed in which an image forming process such as transfer is performed to prevent a reduction in surface resistance due to the adsorption of moisture on the surface of a photoreceptor and an image deletion caused by the reduction.

These techniques have improved the electrical, optical and photoconductive properties of the photoreceptor for an image forming apparatus, as well as the environmental properties of use, and the image quality accordingly.

FIGS. 6A to 6F are schematic views for explaining the layer structure of the photosensitive member of the image forming apparatus which can be used in the present embodiment, and show different traveling characteristics of the photosensitive member. Is shown.

The photosensitive member 200 shown in FIG. 6A has a photosensitive layer 202 provided on a support 201 for the photosensitive member. The photosensitive layer 202 is composed of a photoconductive layer 203 made of a-Si: H, X and having photoconductivity.

The photosensitive member 200 shown in FIG. 6B has a photosensitive layer 202 provided on a support 201 for the photosensitive member. The photosensitive layer 202 includes a photoconductive layer 203 made of a-Si: H, X and having photoconductivity, and an amorphous silicon-based and / or amorphous carbon-based surface layer 2.
04.

The photosensitive member 200 shown in FIG. 6C has a photosensitive layer 202 provided on a support 201 for the photosensitive member. The photosensitive layer 202 includes a photoconductive layer 203 made of a-Si: H, X and having photoconductivity, and an amorphous silicon-based and / or amorphous carbon-based surface layer 2.
04, an amorphous silicon-based charge injection blocking layer 205 between the photoconductive layer 203 and the support 201, and a photoconductive layer 2
03 and an amorphous silicon-based charge injection blocking layer 205 ′ between the surface layer 204 and the surface layer 204.

The photosensitive member 200 shown in FIGS. 6D and 6E
Is a photosensitive layer 20 on a support 201 for a photosensitive member.
2 are provided. This photosensitive layer 202 is
3, a charge generation layer 20 made of a-Si: H, X
7 and the charge transport layer 208, an amorphous silicon-based material,
And / or a charge injection blocking layer 205 provided between the amorphous carbon-based surface layer 204, the photoconductive layer 203 and the support 201, and / or between the photoconductive layer 203 and the surface layer.
205 '.

The photosensitive member 200 shown in FIG. 6F has a photosensitive layer 202 provided on a support 201 for the photosensitive member. The photosensitive layer 202 is composed of a charge generation layer 207 and a charge transport layer 208 made of a-Si: H, X constituting a photoconductive layer 203, and an amorphous silicon-based and / or amorphous carbon-based surface layer 204. I have. Although not particularly shown, between the photoconductive layer 203 and the support 201 and / or between the photoconductive layer 203 and the surface layer 20.
4, there may be charge injection blocking layers 205, 205 '.

[Support] The support 201 may be conductive or electrically insulating. As the conductive support, Al, Cr, Mo, Au, In, Nb, Te, V,
Metals such as Ti, Pt, Pd, and Fe, and alloys thereof;
For example, stainless steel is used. Further, a film or sheet of a synthetic resin such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polystyrene, polyamide, etc., at least the surface of the electrically insulating support such as glass, ceramic or the like on the side on which the photosensitive layer is formed, A support subjected to a conductive treatment can also be used.

[Photoconductive Layer] In this embodiment, in order to effectively achieve the object, the photosensitive layer 2 is formed on the support 201 or, if necessary, on the undercoat layer (not shown).
The photoconductive layer 203 constituting a part of the layer 02 is manufactured by a vacuum deposition film forming method with numerical values of film forming parameters appropriately set so as to obtain desired characteristics. Specifically, for example, a glow discharge method (low-frequency CVD method, high-frequency CV
AC method such as D method or microwave CVD method, or DC discharge CVD method), sputtering method, vacuum deposition method, ion plating method, optical CVD method, thermal CV
It can be formed by various thin film deposition methods such as the D method. These thin film deposition methods are appropriately selected and adopted depending on factors such as the manufacturing conditions, the degree of load under capital investment, the manufacturing scale, and the characteristics desired for a photoconductor for an image forming apparatus to be manufactured. Since it is relatively easy to control the conditions for manufacturing a photoreceptor for an image forming apparatus having the following characteristics, the glow discharge method, particularly the RF band, the μW band,
Alternatively, a high-frequency glow discharge method using a power supply frequency in the VHF band is preferable.

In order to form the photoconductive layer 203 by the blow discharge method, basically, as is well known, silicon atoms Si
Source gas for supplying hydrogen and a source gas for supplying H and / or halogen atoms X capable of supplying hydrogen atoms H
Is supplied in a desired gas state into a reaction vessel in which the inside can be reduced in pressure, and a glow discharge is generated in the reaction vessel, which is previously set at a predetermined position. A-Si: H, on a predetermined support 201,
What is necessary is just to form the layer which consists of X.

In addition, the effective source gas for supplying halogen atoms used in the present embodiment is, for example,
Gaseous or gasifiable halogen compounds such as halogen gas, halides, interhalogen compounds containing halogen, and silane derivatives substituted with halogen are preferred. Further, a gaseous or gasifiable silicon hydride compound containing a halogen atom which contains a silicon atom and a halogen atom as constituent elements can also be mentioned as an effective compound.

Generally, when a-Si does not contain an atom for controlling conductivity, it has a weak n-type conduction characteristic. Therefore, in the negative a-Si of the present invention, an atom for controlling conductivity is contained (doped). It may not be necessary, but may contain an atom for controlling conductivity as necessary, for example, to make it i-type or to expand the latitude of manufacturing stability.

The above-mentioned atoms for controlling conductivity include so-called impurities in the field of semiconductors, and include atoms belonging to Group IIIb of the Periodic Table giving P-type conduction characteristics (hereinafter referred to as “Group IIIb atoms”). ) Or an atom belonging to the group Vb of the periodic table giving n-type conduction characteristics (hereinafter referred to as “Vb
Group atom. " ) Can be used.

As the Group IIIb atoms, specifically, boron (B), aluminum (Al), gallium (Ga),
There are indium (In), thallium (Tl) and the like, and B, Al and Ga are particularly preferable. Group Vb atoms include:
Specifically, phosphorus (P), arsenic (As), antimony (S
b), bismuth (Bi) and the like, and P and As are particularly preferable.

[0066] being effectively used as a raw material for the Vb atoms introduced as the for introducing phosphorus atoms, PH _3, P
Phosphorus hydride such as ₂ H ₄ , PH ₄ l, PF ₃ , PF ₅ , PC
phosphorus halides such as l ₃ , PCl ₅ , PBr ₃ , PBr ₅ , and Pl ₃ . In addition, AsH ₃ , AsF ₃ ,
AsCl ₃ , AsBr ₃ , AsF ₅ , SbH ₃ , SbF
_{3, SbF 5, SbCl 3,} SbCl 5, BiH 3, B
iCl ₃ , BiBr _{3 and the} like can also be mentioned as effective starting materials for introducing a group Vb atom.

[Surface Layer] In the present embodiment, the photoconductive layer 20 formed on the support 201 as described above is used.
It is preferable that an amorphous silicon-based surface layer 204 and / or an amorphous carbon-based surface layer 204 be further formed on the surface layer 3. The surface layer 204 has a free surface and is provided in order to achieve the object of the present invention mainly with respect to moisture resistance, continuous repeated use characteristics, electric pressure resistance, use environment characteristics, and durability.

The surface layer 204 can be made of any material as long as it is an amorphous silicon-based material. For example, amorphous silicon (H) containing a hydrogen atom H and / or a halogen atom X and further containing a carbon atom C may be used. Hereinafter, referred to as “a-SiC: H, X”), a hydrogen atom H and / or
Alternatively, amorphous silicon containing a halogen atom X and further containing an oxygen atom O (hereinafter referred to as “a-SiO: H,
X ". ), Hydrogen atom H and / or halogen atom X
, Amorphous silicon further containing a nitrogen atom N (hereinafter referred to as “a-SiN: H, X”), hydrogen atom H and / or halogen atom X, and further carbon atom C, oxygen atom O, Amorphous silicon containing at least one of nitrogen atoms N (hereinafter referred to as “a-SiCON:
H, X ". ) Are suitably used.

The surface layer 204 is formed, for example, by a blow discharge method (low frequency CVD method, high frequency CVD method, or microwave C
AC discharge CVD method such as VD method, or DC discharge CVD method
Method, etc.), a sputtering method, a vacuum evaporation method, an ion plating method, an optical CVD method, a thermal CVD method, and other well-known thin film deposition methods. These thin film deposition methods are appropriately selected and adopted depending on factors such as manufacturing conditions, the degree of load under capital investment, the manufacturing scale, and the characteristics desired for a photoconductor for an image forming apparatus to be manufactured.

The thickness of the surface layer 204 in this embodiment is usually 0.01 to 3 μm, preferably 0.05 to 3 μm.
It is desirable that the thickness be 2 μm, most preferably 0.1 to 1 μm. If the thickness is less than 0.01 μm, the surface layer is lost due to abrasion or the like during use of the photoreceptor, and if the thickness exceeds 3 μm, a decrease in electrophotographic characteristics such as an increase in residual potential may be observed. .

In addition, it is preferable to use an amorphous carbon film mainly composed of carbon (hereinafter referred to as “aC: H”) as the surface layer 204. Further, an amorphous carbon film having a bond with fluorine inside and / or on the outermost surface (hereinafter referred to as “a-
C: H: F ". ) Are preferably used. a
-C: H has excellent water repellency, low friction, and a-S
It has a hardness equal to or higher than iC, and has an effect of preventing image blurring in a high humidity environment even when a heater for environmental measures is removed. In addition, it is possible to reduce the movement of the charge accelerating particles and the magnetic particles to the photoconductor due to the mechanical friction and the wear of the photoconductor.

[Charge Injection Blocking Layer] In the photoreceptor for an image forming apparatus according to the present embodiment, the function of preventing charge injection from the support 201 side between the support 201 and the photoconductive layer 203 is described. A charge injection blocking layer 205 having a function of preventing charge injection from the surface layer side may be provided between the photoconductive layer 203 and the surface layer 204.

The above-described charge injection blocking layer 205 is formed as a lower injection blocking layer (UBL; Under Blocking Layer).
er), a charge injection blocking layer 205 ′ described below is referred to as an upper blocking layer (Top Blocking Layer).

The charge injection blocking layers 205 and 205 ′
Has a function of preventing charges from being injected from the support or the surface layer side to the photoconductive layer side when the photosensitive layer is subjected to a charging treatment of a fixed polarity on its free surface. It is preferable to have a so-called polarity dependency in which such a function is not exerted when subjected to a charging treatment of the opposite polarity.

In order to provide such a function, the charge injection blocking layers 205 and 205 'contain a relatively large number of atoms or the like for controlling conductivity as compared with the photoconductive layer. The atoms for controlling the conductivity contained in the charge injection blocking layers 205, 205 'may be distributed evenly and uniformly in this layer, or may be contained evenly in the layer thickness direction. However, there may be a portion which is contained in a state of being unevenly distributed.
When the distribution concentration is non-uniform, it is preferable to include the UBL 205 so as to be distributed more on the support side and the TBL 205 ′ so as to be distributed more on the surface layer side. In any case, it is necessary that the metal is uniformly contained in a uniform distribution in the in-plane direction parallel to the surface of the support 201 from the viewpoint of making the characteristics in the in-plane direction uniform.

As the atoms for controlling the conductivity contained in the charge injection blocking layers 205 and 205 ′, there can be mentioned so-called impurities in the semiconductor field, and “Group III atoms” or “Group V atoms” may be used. Can be used.

In this embodiment, the charge injection blocking layer 2
The layer thickness of the layers 05 and 205 'is preferably from 0.05 to 205 from the viewpoints of obtaining desired electrophotographic characteristics and economical effects.
5 μm, more preferably 0.1-4 μm, most preferably 0.1 μm.
It is desirable that the thickness be 5 to 3 μm.

Further, in the photoreceptor for an image forming apparatus according to the present embodiment, for the purpose of further improving the adhesion between the support 201 and the photoconductive layer 203 or the UBL 205, for example, Si ₃ N ₄ , an adhesion layer composed of an amorphous material or the like containing SiO ₂ , SiO, or silicon atoms as a base and containing hydrogen atoms and / or halogen atoms, and carbon atoms and / or oxygen atoms and / or nitrogen atoms. It may be provided. Further, as described above, a light absorbing layer for preventing generation of an interference pattern due to light reflected from the support may be provided.

Each of the above-mentioned layers is formed, for example, by a high frequency plasma CVD method (RF-PC) using an RF band of 13.56 MHz or the like.
VD) and a known apparatus and a film forming method such as a high frequency plasma CVD method (VHF-PCVD) using a VHF band of 50 to 450 MHz.

The description of the photosensitive member has been completed.

Next, the image forming apparatus and the magnetic brush charging device will be described with reference to FIGS. FIG.
Is a longitudinal sectional view showing a schematic configuration of an image forming apparatus, and FIG. 3 is a schematic diagram showing a schematic configuration of a magnetic brush charging device.

In the image forming apparatus shown in FIG.
When a copy (image forming) start signal is inputted, the pre-exposure lamp 8 rotates in the direction of arrow R1 so that the pre-exposure lamp 8 uniformly removes the charge, and then the magnetic brush charger 3 sets the polarity and potential to a predetermined value. Is uniformly charged.

Here, the photosensitive member 1 is a rotating drum type electrophotographic photosensitive member, and in the present embodiment, an aC: H (amorphous silicon photosensitive member having a diameter of 30 mm, FIG.
(Layer structure of (c)), and 100 in the direction of arrow R1.
It is driven to rotate at a process speed (peripheral speed) of mm / sec.

The magnetic brush charging device 3 shown in FIG. 3 includes a magnetic brush charging member 30 as a contact charging member in contact with the photoreceptor 1 and a charging bias applying power source (charging bias applying means) for applying a charging bias to the member. ) S1. The magnetic brush charging member 30 is a sleeve rotation type device, and includes a core 31 and a magnet roller (magnetic field generating means) 32 as a cylindrical multipolar magnetic body provided concentrically around the core 31. A non-magnetic charging sleeve (magnetic particle carrier) 33 provided rotatably and concentrically around the cored bar 31 outside the magnet roller 32; The magnetic brush layer 34 is formed by attracting and holding magnetic particles by the magnetic force of the magnet roller 32 inside the sleeve. The magnetic brush charging member 30 has both ends of the metal core 31 bearing substantially parallel to the photoreceptor 1 to be charged, and forms a magnetic brush layer 34 on the surface of the photoreceptor 1 to form a charging nip n having a predetermined width. Are arranged in contact with each other.

The magnetic brush charging member 30 rotates clockwise (in the direction of arrow R3) opposite to the rotation direction (direction of arrow R1) of the photoconductor 1 in the charging nip n (direction of arrow R1), or the charging nip n In this case, the photosensitive member 1 is rotated counterclockwise, which is the forward direction of the rotating direction of the photosensitive member 1, and the surface of the photosensitive member 1 is rubbed by the magnetic brush layer 34 at the charging nip n.

Then, a predetermined charging bias is applied to the magnetic brush layer 34 via the charging sleeve 33 by the charging bias applying power source S1 to apply a DC voltage (Vdc) of a predetermined polarity and potential.
The surface (outer peripheral surface) of the photoreceptor 1 which is applied by a vibration voltage (Vdc + Vac: AC application method) in which an AC voltage Vac is superimposed and which is rotationally driven is applied with a predetermined polarity by a contact charging method. -Uniformly charged to potential.

Here, the magnet roller 32 is usually
Magnetic materials such as ferrite magnets and rubber magnets are used, and have many circumferential magnetic poles.

The magnetic particles forming the magnetic brush layer 34 include a magnetic iron oxide (ferrite) powder such as Cu—Zn—Fe—O, a magnetite powder, and a magnetic material such as ferrite or magnetite dispersed in a resin. A well-known magnetic toner material or the like is generally used.

The magnetic brush charging member 30 forms a magnetic brush layer 34 by attaching conductive magnetic particles to a rotatable non-magnetic charging sleeve 33 by the magnetic force of a magnet 32. The magnetic brush layer 34 is brought into contact with the surface of the photoreceptor 1 to form a charging nip n having a predetermined width. The magnetic brush charging member 30 is supplied with a bias in which a rectangular alternating voltage of 2 MHz and 750 V are superimposed on a charging bias of DC voltage -700 V from a charging bias applying power source S1. Is uniformly charged to approximately -550 V by charge injection charging.

On the other hand, in the reader section of the image forming apparatus shown in FIG. By scanning while irradiating the original G, the reflected light of the illumination scanning light from the original surface is imaged by the short focus lens array and is incident on the CCD sensor. The CCD sensor includes a light receiving unit, a transfer unit, and an output unit. The light signal is converted into a charge signal in the CCD light receiving unit, and the transfer unit sequentially transfers the light signal to the output unit in synchronization with the clock pulse. The obtained analog signal is subjected to well-known image processing, converted into a digital signal, and sent to a printer unit.

In the printer section, an exposing device (laser exposing means) 2 including a solid-state laser element, a polygon mirror rotating at high speed, and the like is applied to the charged surface (surface) of the photoreceptor 1.
Is subjected to scanning exposure E using a laser beam intensity-modulated in accordance with the digital signal of the above-mentioned image information output from the image forming apparatus, and an electrostatic latent image corresponding to the image information of the original image is formed on the surface of the photoconductor 1 Is done. The electrostatic latent image is developed as a toner image by a developing device 4 using a magnetic one-component insulating toner. The developing device 4 has a non-magnetic phenomenon sleeve 41 having a diameter of 16 mm and enclosing a magnet roller (not shown). Is rotated at the same speed as the photoconductor 1 so that the developing sleeve 41 is fixed.
, A developing bias voltage is applied from a developing bias applying power source (not shown). The applied voltage is a DC voltage of -350V,
A jumping phenomenon is caused between the developing sleeve 41 and the photoreceptor 1 using a superimposed rectangular AC voltage having a frequency of 1.8 MHz and a peak-to-peak voltage of 1.6 kV.

On the other hand, a recording material P such as paper is supplied from a paper feeding unit, and the photosensitive member 1 is brought into contact with a medium-resistance transfer roller 7 serving as a contact transfer unit brought into contact with the photosensitive member 1 with a predetermined pressing force. The toner is supplied to the transfer nip T at a predetermined timing. A predetermined transfer bias voltage is applied to the transfer roller 7 from a transfer bias application power supply (not shown). In the present embodiment, the transfer roller 7 has a roller resistance of 5 × 10 ⁸ Ω.
The transfer was performed by applying a DC voltage of + 2000V. The recording material P supplied to the transfer nip portion T is nipped and conveyed in the transfer nip portion T, and a toner image formed and carried on the surface of the photoreceptor 1 on its surface side is sequentially subjected to electrostatic force, pressing force, and the like. Is transcribed.

Further, the recording material P to which the toner image has been transferred
Is separated from the surface of the photoreceptor 1 and is introduced into a fixing device 6 of a heat fixing type or the like, where the toner image is fixed, and is discharged on a discharge tray 12 as an image formed product (print, copy).

On the other hand, the surface of the photoreceptor after the transfer of the toner image to the recording material P is cleaned by removing the contaminants such as residual toner by the cleaning device 5, and is used for the next image formation.

In the image forming apparatus of the present embodiment shown in FIG. 2, image forming is performed by binding four process devices of a photoreceptor 1, a magnetic brush charging device 3, a developing device 4, and a cleaning device 5 to a cartridge container 11. A cartridge that can be freely attached to and detached from the apparatus main body is configured to be freely removable. However, the image forming apparatus according to the present invention is not limited to the process cartridge type.

Next, the magnetic brush charging device 3 used in the present embodiment will be described in detail.

In FIG. 3, the magnetic brush charging member 30
The magnetic particles constitute a magnetic brush layer by a magnetic field on a non-magnetic charging sleeve 33 having an outer diameter of 16 mm rotatably supported and provided with an immovable magnet roller 32 therein. The magnetic particles are transported with the rotation in the R1 direction. Also, the charging sleeve 33
Is rotated in the counter direction with respect to the photoconductor 1 rotating in the direction of the arrow R1. It is spinning. By applying a charging bias to the above-described charging sleeve 33, charges are given from the magnetic particles onto the photoconductor 1, and the surface of the photoconductor 1 is charged to a potential corresponding to the charging bias. The higher the rotation speed, the better the charging uniformity tends to be.

Ferrite particles are preferable as the magnetic carrier used as the magnetic particles, and those containing a metal element such as copper, zinc, manganese, magnesium, iron, lithium, strontium, and barium are preferably used as the composition. Further, the average particle diameter (median diameter of 50% by volume) is 10 to 100 μm, and the saturation magnetization is 20 to 250 emu / c.
m ³ and a resistance of 1 × 10 ² to 1 × 10 ¹⁰ Ω · cm are used, but considering that there is an insulation defect such as a pinhole in the photoreceptor 1, it is 1 × 10 ⁶ Ω · cm or more. It is preferable to use On the other hand, in order to improve the charging performance, it is better to use one having a resistance as small as possible. Therefore, in this embodiment, the average particle diameter is 25 μm,
Saturation magnetization 200 emu / cm ³ , resistance 5 × 10 ⁶ Ω ·
cm of magnetic particles whose resistance has been adjusted by oxidizing and reducing the ferrite surface.

Here, the resistance value of the magnetic carrier was determined by placing 2 g of the carrier in a metal cell having a bottom area of 228 mm ² ,
The measurement was performed by applying a load of 6.6 kg / cm ² and applying a DC voltage of 100 V.

The magnetic brush charging member 30 and the photosensitive member 1
The nip width of the charging nip portion n formed between the surface and the surface is adjusted to be approximately 6 mm.

Next, a method of controlling the charging bias application power supply S1 applied to the magnetic brush charging member 30 used in the present embodiment will be described.

FIG. 1 is an explanatory diagram showing a control method at the time of applying an oscillating voltage of the charging bias applying power source S1 in the present embodiment.

In the figure, a table is applied in which the peak voltage of the AC voltage Vac is linearly applied by adding an offset amount of 50 V to the absolute value of the DC voltage Vdc.

Here, the offset amount depends on the environment used,
It is preferable that the temperature is appropriately selected according to the pressure resistance characteristics of the surface layer of the photoconductor 1 and the resistance of the magnetic particles. Also, the table may be provided with a gradient or the like in addition to the linear table.

FIG. 7 is a diagram showing the amount of magnetic particles detached from and adhered to the photoconductor 1 from the magnetic brush layer 34 when idle rotation is performed for a predetermined time according to the present embodiment.

In the figure, the amount of magnetic particles detached and attached to the morphus silicon photoconductor (a-Si) with respect to the vibration voltage (Vdc + V'ac) applied to the magnetic brush charging member 30 is improved as shown in FIG. The amount of magnetic particles detached and attached to the photoreceptor 1 was reduced to the same level as that of the organic photoreceptor.

According to the method of applying the charging bias to the magnetic brush charging member 30 as described above, 50,000 sheets of paper were passed, and the magnetic particles from the end of the charging sleeve 33 as the photosensitive member 1 Amorphous silicon photoconductor (a
-Si), the amount of detachment / adhesion to the magnetic brush layer 3
The initial charging performance was able to be maintained without reducing the magnetic particles constituting No. 4. In addition, vertical streaks and fogging, which were problems caused by this, could be prevented.

In the above description, the case where an amorphous silicon-based photoconductor (a-Si) is used as the photoconductor 1 has been described. However, the DC voltage Vdc applied to the magnetic brush charging member 30 and the post-charging voltage The present invention can also be applied to a photosensitive member having a large potential difference from the charged potential of the photosensitive member 1, that is, a photosensitive member having a large electrostatic capacity. In this case, the same effect as described above can be obtained. be able to.

[0109]

As described above, according to the present invention, of the DC voltage and the AC voltage applied to the magnetic brush charging member as the charging bias, the peak voltage of the AC voltage is changed according to the magnitude of the DC voltage. By changing
Prevent the decrease of magnetic particles, maintain the initial charging performance,
In addition, defects such as vertical stripes and fogging can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a charging bias control method according to the present invention.

FIG. 2 is a longitudinal sectional view illustrating a schematic configuration of an image forming apparatus to which the present invention is applied.

FIG. 3 is a schematic diagram showing a schematic configuration of a magnetic brush charging device according to the present invention.

FIG. 4 is a potential diagram showing charging performance of a conventional magnetic brush charging device.

FIG. 5 is a view showing the detachment / attachment amount of magnetic particles by a conventional charging bias control method.

FIGS. 6A to 6F are schematic diagrams showing layer configurations of different amorphous silicon-based photoconductors.

FIG. 7 is a diagram showing the detachment / attachment amount of magnetic particles according to the charging bias control method of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 charged member (image carrier, photoreceptor) 3 magnetic brush charging device 30 magnetic brush charging member 32 magnetic field generating means (magnet roller) 33 magnetic particle carrier (charging sleeve) 34 magnetic brush layer S1 charging bias applying means (charging Power supply for bias application)

Claims (6)

[Claims] 1. A magnetic brush charging member is formed by holding magnetic particles on the surface of a magnetic particle carrier by a magnetic field generating means,
In the magnetic brush charging method of applying a charging bias to the magnetic brush charging member by bringing the magnetic particles into contact with a member to be charged and charging the member to be charged via the magnetic particles, the method is applied to the magnetic brush charging member. A magnetic brush charging method, wherein a DC voltage and an AC voltage having a peak voltage changed according to the magnitude of the DC voltage are applied as a charging bias. 2. The magnetic brush charging method according to claim 1, wherein the magnetic field generating means has a plurality of circumferential magnetic poles. 3. The magnetic brush charging method according to claim 1, wherein the member to be charged is an amorphous silicon photosensitive member. 4. A magnetic particle carrier, a magnetic field generating means disposed inside the magnetic particle carrier, and a magnetic field generating means which is carried on the surface of the magnetic particle carrier and contacts the member to be charged. A magnetic brush charging member having magnetic particles to be charged, and charging bias applying means for applying a charging bias to the magnetic brush charging member and charging the charged object via the magnetic particles. The charging bias application power supply applies, as a charging bias to be applied to the magnetic brush charging member, a DC voltage and an AC voltage having a peak voltage changed according to the magnitude of the DC voltage. Magnetic brush charging device. 5. The magnetic brush charging device according to claim 4, wherein said magnetic field generating means has a plurality of circumferential magnetic poles. 6. The magnetic brush charging device according to claim 4, wherein the member to be charged is an amorphous silicon photosensitive member.