JP5935700B2 - Image forming apparatus, image forming method, and process cartridge - Google Patents

Description

  The present invention relates to an image forming apparatus, an image forming method, and a process cartridge.

Patent Document 1 states that “an electrophotographic photosensitive member having an intermediate layer and a photosensitive layer on a conductive support in this order, the photosensitive layer contains a phthalocyanine-based compound, and the intermediate layer includes an organometallic compound and It contains a silane coupling agent or a product from them, and the time from the uniform charge of the photoreceptor to the next charge (t _cycle ) and from the pre-charge exposure (PCL) to the next uniform charge An image forming apparatus characterized in that the time (t _PCL-charge ) is t _cycle ≦ 3 sec.t _PCL-charge / t _cycle ≦ 0.5 ”has been proposed.

  Patent Document 2 discloses that “a photosensitive member, a charging device that uniformly charges the surface of the photosensitive member, an image exposure device that performs image exposure after uniform charging to form an electrostatic latent image, and the static device described above. A developing device that develops an electrostatic latent image, a transfer device that applies a transfer bias having a polarity opposite to the charging polarity of the charging device to transfer the developed image to a transfer material, and a bias that has a polarity opposite to that of the transfer device. In an image forming apparatus comprising a preliminary static elimination device and a static elimination device that neutralizes residual charges on the photoconductor, the photoconductor has at least a charge generating material, a hole transport material, and a specific electron transport material on a conductive substrate. An image forming apparatus having a photosensitive layer composed of a single layer and containing a control means for controlling the output of the preliminary static eliminator has been proposed.

  Further, Patent Document 3 states that “a predetermined image formation consisting of a photosensitive member speed, a photosensitive member charging potential for image formation, and a charge removal amount after image formation, which causes a residual potential increase in the photosensitive member when image formation is repeated. When the photosensitive member is driven and charged under the conditions, and the static eliminator removes static electricity, the photosensitive member is driven at the photosensitive member speed without charging with respect to the absolute value A of the rising speed VL or VR. VL (VL: photoconductor surface potential of a solid image portion when the photoconductor is exposed to form a solid image) or VR (VR: photosensitivity after static elimination) when the photoconductor is irradiated with light from the photostatic device. An electrophotographic image forming apparatus that irradiates a photoconductor from the photostatic device with a light quantity with which the decrease rate absolute value B or C of (body surface residual potential) is equal or larger is proposed.

Japanese Patent No. 4233123 Patent No. 4850033 JP 2010-49190 A

  An object of the present invention is to provide an image forming apparatus capable of obtaining an image in which a density change (hereinafter referred to as “ghost”) due to the history of the previous cycle is suppressed.

The above problem is solved by the following means. That is,
The invention according to claim 1
From a conductive substrate, a binder resin, metal oxide particles, and an electron-accepting compound represented by the following general formula (1-1) and the following general formula (1-2) provided on the conductive substrate An electrophotographic photoreceptor having an undercoat layer containing at least one selected, and a photosensitive layer provided on the undercoat layer,
A drive unit for rotationally driving the electrophotographic photosensitive member;
A charging member for charging the surface of the electrophotographic photosensitive member;
A voltage application unit for a charging member for applying a voltage to the charging member;
A latent image forming unit that forms an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
A developing member that develops the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image;
A voltage applying unit for the developing member for applying a voltage to the developing member;
A transfer member for transferring a toner image formed on the surface of the electrophotographic photosensitive member to a transfer target;
A voltage applying unit for the transfer member that applies a voltage to the transfer member;
After transferring the toner image, a charge removing unit that exposes the surface of the electrophotographic photosensitive member to remove charge;
After the image formation is completed, when the output number of the same image continuously formed and the process speed of the image formation have a predetermined relationship among the completed image formation information, the voltage is applied to the charging member and the transfer member. And the drive unit, the voltage applying unit for the charging member, and the transfer member for rotating the electrophotographic photosensitive member in a state where the surface of the electrophotographic photosensitive member is exposed by the charge eliminating unit. A voltage application unit, and a control unit for controlling the static elimination unit,
An image forming apparatus comprising:

(In General Formula (1-1) and General Formula (1-2), n11, n11 ′, n12, n12 ′, n13, and n14 each independently represent an integer of 0 or more and 3 or less, provided that n11 and At least one of n12 represents an integer of 1 to 3. At least one of n11 ′ and n12 ′ represents an integer of 1 to 3. At least one of n14 and n13 represents an integer of 1 to 3. m11, m11′m12 and m12 ′ each independently represents an integer of 0 or 1. r11 represents an integer of 2 or more and 10 or less, and R ¹¹ , R ^{11 ′} , R ¹² and R ^{12 ′} each independently represent carbon number. Represents an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms.)

The invention according to claim 2
Voltage application for the charging member is performed such that the control unit applies the voltage applied during the completed image formation to the charging member, and applies the voltage applied during the completed image formation to the transfer member. The image forming apparatus according to claim 1, wherein the image forming unit controls a voltage application unit for the transfer unit and the transfer member.

The invention according to claim 3
The control unit applies a voltage to the charging member that is lower than the voltage applied during the completed image formation, and applies a voltage higher than the voltage applied during the completed image formation to the transfer member. The image forming apparatus according to claim 1, wherein the voltage applying unit for the charging member and the voltage applying unit for the transfer member are controlled.

The invention according to claim 4
The image forming apparatus according to claim 1, wherein the control unit further controls a voltage application unit for the developing member so as to apply a voltage to the developing member.

The invention according to claim 5
The predetermined relationship between the number of outputs of the same image formed continuously and the process speed of the image formation is such that the number of outputs of the same image formed continuously is equal to or greater than the predetermined number of outputs. The image forming apparatus according to claim 1, wherein a forming process speed is a relationship equal to or lower than a predetermined speed.

The invention according to claim 6
The predetermined relationship between the number of outputs of the same image formed continuously and the process speed of the image formation is a relationship represented by the following formula (11). Image forming apparatus.
Formula (11): OP / PS ≧ 2.2
(In the formula (11), OP indicates the number of output of the same image formed continuously (sheets). PS indicates the process speed (mm / s) of image formation.)

The invention according to claim 7 provides:
The photosensitive layer of the electrophotographic photoreceptor has a charge generation layer and a charge transport layer,
The charge transport layer comprises a charge transport material represented by the following general formula (2), a repeating unit represented by the following general formula (3), and a polycarbonate copolymer comprising a repeating unit represented by the following general formula (4) The image forming apparatus according to claim 1, comprising a united image.

(In General Formula (2), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ may be the same or different, and each represents a hydrogen atom, an alkyl group, an alkoxyl group, A halogen atom or a substituted or unsubstituted aryl group, and m1 and n2 each independently represents 0 or 1.

(In General Formula (3) and General Formula (4), R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, carbon A cycloalkyl group having 5 to 7 carbon atoms, or an aryl group having 6 to 12 carbon atoms, X represents a phenylene group, a biphenylene group, a naphthylene group, a linear or branched alkylene group, or a cycloalkylene group. .)

The invention according to claim 8 provides:
From a conductive substrate, a binder resin, metal oxide particles, and an electron-accepting compound represented by the following general formula (1-1) and the following general formula (1-2) provided on the conductive substrate A first step of charging the surface of the electrophotographic photosensitive member having an undercoat layer containing at least one selected, and a photosensitive layer provided on the undercoat layer;
A second step of forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
A third step of developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image;
A fourth step of transferring a toner image formed on the surface of the electrophotographic photosensitive member to a transfer target;
After transferring the toner image, a fifth step of exposing the surface of the electrophotographic photosensitive member to remove electricity,
After the image formation is completed, when the output number of the same image continuously formed and the process speed of the image formation have a predetermined relationship among the completed image formation information, the voltage is applied to the charging member and the transfer member. And the sixth step of rotating the electrophotographic photosensitive member in a state where the surface of the electrophotographic photosensitive member is exposed by the static eliminator,
An image forming method comprising:

(In General Formula (1-1) and General Formula (1-2), n11, n11 ′, n12, n12 ′, n13, and n14 each independently represent an integer of 0 or more and 3 or less, provided that n11 and At least one of n12 represents an integer of 1 to 3. At least one of n11 ′ and n12 ′ represents an integer of 1 to 3. At least one of n14 and n13 represents an integer of 1 to 3. m11, m11′m12 and m12 ′ each independently represents an integer of 0 or 1. r11 represents an integer of 2 or more and 10 or less, and R ¹¹ , R ^{11 ′} , R ¹² and R ^{12 ′} each independently represent carbon number. Represents an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms.)

The invention according to claim 9 is:
9. The image forming method according to claim 8, wherein in the sixth step, a voltage applied at the time of completed image formation is applied to the charging member, and a voltage applied at the time of completed image formation is applied to the transfer member. .

The invention according to claim 10 is:
In the sixth step, a voltage lower than a voltage applied at the time of completed image formation is applied to the charging member, and a voltage higher than a voltage applied at the time of completed image formation is applied to the transfer member. Item 9. The image forming method according to Item 8.

The invention according to claim 11 is:
The image forming method according to claim 8, wherein a voltage is further applied to the developing member in the sixth step.

The invention according to claim 12
The predetermined relationship between the number of outputs of the same image formed continuously and the process speed of the image formation is such that the number of outputs of the same image formed continuously is equal to or greater than the predetermined number of outputs. The image forming method according to claim 8, wherein a forming process speed is a relationship equal to or lower than a predetermined speed.

The invention according to claim 13 is:
The predetermined relationship between the number of outputs of the same image formed continuously and the process speed of the image formation is a relationship represented by the following formula (11). Image forming method.
Formula (11): OP / PS ≧ 2.2
(In the formula (11), OP indicates the number of output of the same image formed continuously (sheets). PS indicates the process speed (mm / s) of image formation.)

The invention according to claim 14 is:
The photosensitive layer of the electrophotographic photoreceptor has a charge generation layer and a charge transport layer,
The charge transport layer comprises a charge transport material represented by the following general formula (2), a repeating unit represented by the following general formula (3), and a polycarbonate copolymer comprising a repeating unit represented by the following general formula (4) The image forming method according to any one of claims 8 to 13, comprising a coalescence.

(In General Formula (2), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ may be the same or different, and each represents a hydrogen atom, an alkyl group, an alkoxyl group, A halogen atom or a substituted or unsubstituted aryl group, and m1 and n2 each independently represents 0 or 1.

(In General Formula (3) and General Formula (4), R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, carbon A cycloalkyl group having 5 to 7 carbon atoms, or an aryl group having 6 to 12 carbon atoms, X represents a phenylene group, a biphenylene group, a naphthylene group, a linear or branched alkylene group, or a cycloalkylene group. .)

The invention according to claim 15 is:
From a conductive substrate, a binder resin, metal oxide particles, and an electron-accepting compound represented by the following general formula (1-1) and the following general formula (1-2) provided on the conductive substrate An electrophotographic photoreceptor having an undercoat layer containing at least one selected, and a photosensitive layer provided on the undercoat layer,
A drive unit for rotationally driving the electrophotographic photosensitive member;
A charging member for charging the surface of the electrophotographic photosensitive member;
A voltage application unit for a charging member for applying a voltage to the charging member;
A transfer member for transferring a toner image formed on the surface of the electrophotographic photosensitive member to a transfer target;
A voltage application unit for a transfer member for applying a voltage to the transfer member;
After transferring the toner image, a charge removing unit that exposes the surface of the electrophotographic photosensitive member to remove charge;
After the image formation is completed, when the output number of the same image continuously formed and the process speed of the image formation have a predetermined relationship among the completed image formation information, the voltage is applied to the charging member and the transfer member. And the drive unit, the voltage applying unit for the charging member, and the transfer member for rotating the electrophotographic photosensitive member in a state where the surface of the electrophotographic photosensitive member is exposed by the charge eliminating unit. A voltage application unit, and a control unit for controlling the static elimination unit,
With
A process cartridge attached to and detached from the image forming apparatus.

(In General Formula (1-1) and General Formula (1-2), n11, n11 ′, n12, n12 ′, n13, and n14 each independently represent an integer of 0 or more and 3 or less, provided that n11 and At least one of n12 represents an integer of 1 to 3. At least one of n11 ′ and n12 ′ represents an integer of 1 to 3. At least one of n14 and n13 represents an integer of 1 to 3. m11, m11′m12 and m12 ′ each independently represents an integer of 0 or 1. r11 represents an integer of 2 or more and 10 or less, and R ¹¹ , R ^{11 ′} , R ¹² and R ^{12 ′} each independently represent carbon number. Represents an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms.)

According to the first aspect of the present invention, there is provided an image forming apparatus capable of obtaining an image in which a ghost is suppressed as compared with a case where the specific control unit is not provided.
According to the second aspect of the invention, the control unit applies a voltage lower than the voltage applied at the time of completed image formation to the charging member, and applies a voltage higher than the voltage applied at the time of completed image formation. There is provided an image forming apparatus capable of obtaining an image in which a ghost is suppressed as compared with a case where control is performed so as to apply to a transfer member.
According to the third aspect of the present invention, the control unit controls to apply the voltage applied during the completed image formation to the charging member and apply the voltage applied during the completed image formation to the transfer member. An image forming apparatus that suppresses the wear of the electrophotographic photosensitive member is provided as compared with the case of doing so.
According to the fourth aspect of the present invention, compared to the case where the control unit does not control to apply a voltage to the developing member, the adhesion of toner to the electrophotographic photosensitive member during the control by the specific control unit is suppressed. An image forming apparatus is provided.
According to the fifth and sixth aspects of the present invention, the number of outputs of the same continuously formed image is equal to or greater than a predetermined output number, and the image forming process speed is equal to or lower than the predetermined speed. There is provided an image forming apparatus capable of obtaining an image in which a ghost is suppressed as compared with a case where a specific control unit is not provided.
According to the invention of claim 7, even if the electrophotographic photosensitive member has the charge transport layer having the above composition, an image forming apparatus capable of obtaining an image with suppressed ghost compared to the case where the specific control unit is not provided. Is provided.

According to the eighth aspect of the present invention, there is provided an image forming method capable of obtaining an image in which a ghost is suppressed as compared with the case where the sixth step is not provided.
According to the ninth aspect of the present invention, in the sixth step, a voltage lower than the voltage applied during the completed image formation is applied to the charging member, and the voltage applied is higher than the voltage applied during the completed image formation. As compared with the case of applying to the transfer member, an image forming method capable of obtaining an image with suppressed ghost is provided.
According to the tenth aspect of the present invention, in the sixth step, the voltage applied during the completed image formation is applied to the charging member, and the voltage applied during the completed image formation is applied to the transfer member. In comparison, an image forming method for suppressing wear of an electrophotographic photosensitive member is provided.
According to the eleventh aspect of the present invention, there is provided an image forming method that suppresses toner adhesion to the electrophotographic photosensitive member when the sixth step is performed, as compared with the case where no voltage is applied to the developing member in the sixth step. The
According to the inventions according to claims 12 and 13, even if the number of outputs of the same continuously formed image is equal to or greater than the predetermined output number and the process speed of image formation is equal to or less than the predetermined speed, There is provided an image forming method capable of obtaining an image in which ghosts are suppressed as compared with the case where there are no six steps.
According to the invention of claim 14, even if the electrophotographic photosensitive member has the charge transport layer having the above composition, an image forming method capable of obtaining an image with suppressed ghost as compared with the case where the specific control unit is not provided. Is provided.

  According to the fifteenth aspect of the present invention, there is provided a process cartridge capable of obtaining an image in which a ghost is suppressed as compared with a case where the specific control unit is not provided.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. 2 is a block diagram illustrating a control unit of the image forming apparatus according to the present exemplary embodiment. FIG. 4 is a flowchart illustrating processing performed by a control unit of the image forming apparatus according to the present exemplary embodiment. It is the schematic which shows an example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. It is the schematic which shows the other example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. It is the schematic which shows the other example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. It is the schematic which shows the other example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. It is the schematic which shows the other example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment. It is the schematic which shows the other example of the layer structure of the electrophotographic photoreceptor which concerns on this embodiment.

  Hereinafter, an exemplary embodiment of the present invention will be described with reference to the drawings.

[Image forming apparatus]
FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to the present embodiment.
As shown in FIG. 1, for example, an electrophotographic photosensitive member (hereinafter referred to as “photosensitive member”) 12 is provided in the image forming apparatus 10 according to the present embodiment. The photoconductor 12 has a cylindrical shape, and is connected to a drive motor 27 (an example of a drive unit) via a drive force propagation member (not shown) such as a gear, and is rotated by the drive motor 27 (FIG. 1). Middle arrow A direction).

  Around the photosensitive member 12, for example, a charging device 15, a latent image forming device 16, a developing device 18, a transfer device 31, a cleaning device 22, and a charge eliminating device 24 are sequentially arranged along the rotation direction of the photosensitive member 12. Has been. The image forming apparatus 10 according to the present embodiment is also provided with a fixing device 26.

Details of each part of the image forming apparatus 10 will be described below.
The photoreceptor 12 includes, for example, a conductive substrate, an undercoat layer formed on the conductive substrate, and a photosensitive layer formed on the undercoat layer. This photosensitive layer may have a two-layer structure of a charge generation layer and a charge transport layer. Further, the photosensitive layer may have a configuration in which a protective layer is provided on the outermost surface.
The undercoat layer includes at least one selected from a binder resin, metal oxide particles, and an electron-accepting compound represented by the general formula (1-1) and the following general formula (1-2). It is comprised including.
The detailed configuration of the photoconductor 12 will be described later.

  The charging device 15 charges the surface of the photoconductor 12. The charging device 15 is provided, for example, in contact or non-contact with the surface of the photoconductor 12, and a charging member 14 that charges the surface of the photoconductor 12, and a power source 28 (voltage for the charging member) that applies a charging voltage to the charging member 14. An example of an application unit). The power source 28 is electrically connected to the charging member 14.

  Examples of the charging member 14 of the charging device 15 include a contact-type charger using a conductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, and the like. Examples of the charging member 14 include a non-contact type roller charger and a known charger such as a scorotron charger using a corona discharge or a corotron charger.

  For example, the charging device 15 (its power supply 28) is electrically connected to a control unit 36 provided in the image forming apparatus 10, and applies a charging voltage to the charging member 14 under the control of the control unit 36. The charging member 14 to which the charging voltage is applied from the charging member 14 charges the photoconductor 12 to a charging potential corresponding to the applied charging voltage. Therefore, the photosensitive member 12 is charged to a different charging potential by adjusting the charging voltage applied from the power source 28.

The latent image forming device 16 (an example of a latent image forming unit) forms an electrostatic latent image on the surface of the charged electrophotographic photosensitive member.
Specifically, for example, the latent image forming device 16 is electrically connected to a control unit 36 provided in the image forming device 10, and the photosensitive member charged by the charging member 14 under the control of the control unit 36. The surface 12 is irradiated with light L modulated based on the image information of the image to be formed, and an electrostatic latent image corresponding to the image of the image information is formed on the photoreceptor 12.

  Examples of the latent image forming device 16 include optical equipment having a light source that exposes light such as semiconductor laser light, LED light, and liquid crystal shutter light imagewise.

The developing device 18 is provided, for example, on the downstream side in the rotation direction of the photoconductor 12 from the irradiation position of the light L by the latent image forming device 16.
For example, a known developer containing toner is accommodated in the developing device 18. For example, the toner is stored in a charged state in the developing device 18. Examples of the toner contained in the developer include a toner having a volume average particle diameter of 3 μm or more and 9 μm or less obtained by a polymerization method.

  The developing device 18 includes, for example, a developing member 18A that develops an electrostatic latent image formed on the surface of the photoreceptor 12 with a developer containing toner, and a power source 32 (for developing member) that applies a developing voltage to the developing member 18A. An example of the voltage application unit of The developing member 18A is electrically connected to the power source 32, for example.

  The developing member 18A of the developing device 18 is selected according to the type of developer, and examples thereof include a developing roll having a developing sleeve with a built-in magnet.

The developing device 18 (its power source 32) is electrically connected to a control unit 36 provided in the image forming apparatus 10, for example, and applies a developing voltage to the developing member 18A under the control of the control unit 36. The developing member 18A to which the developing voltage is applied is charged to a developing potential corresponding to the developing voltage.
Then, the developing member 18A charged to the developing potential holds, for example, the developer accommodated in the developing device 18 on the surface, and the toner contained in the developer is transferred from the developing device 18 to the surface of the photoreceptor 12. Supply. For example, the toner supplied onto the photoconductor 12 adheres to the electrostatic latent image on the photoconductor 12 by electrostatic force. Specifically, for example, the toner contained in the developer by the potential difference in the area where the photosensitive member 12 and the developing member 18A face each other, that is, the potential difference between the surface potential of the photosensitive member 12 and the developing potential of the developing member 18A in the region. Is supplied to the area where the electrostatic latent image is formed on the photosensitive member 12 and the developer contains a carrier, the carrier returns to the developing device 18 while being held by the developing member 18A. Thereby, for example, the electrostatic latent image on the photoconductor 12 is developed by the toner supplied from the developing member 18 </ b> A, and a toner image corresponding to the electrostatic latent image is formed on the photoconductor 12.

For example, the transfer device 31 is provided on the downstream side in the rotation direction of the photoconductor 12 from the position where the developing member 18A is disposed.
The transfer device 31 includes, for example, a transfer member 20 that transfers a toner image formed on the surface of the photoreceptor 12 to a recording medium 30A (an example of a transfer target), and a power supply 30 (transfer) that applies a transfer voltage to the transfer member 20. An example of a voltage application unit for a member). The transfer member 20 has, for example, a cylindrical shape, and conveys the recording medium 30 </ b> A with the photoreceptor 12. The transfer member 20 is electrically connected to, for example, a power supply 30.

  As the transfer member 20 of the transfer member 20, for example, a contact transfer charger using a belt, a roller, a film, a rubber blade or the like, a scorotron transfer charger using a corona discharge, a corotron transfer charger, or the like is known per se. A non-contact type transfer charger is exemplified.

The transfer device 31 (its power supply 30) is electrically connected to a control unit 36 provided in the image forming apparatus 10, for example, and applies a transfer voltage to the transfer member 20 under the control of the control unit 36. The transfer member 20 to which the transfer voltage is applied is charged to a transfer potential corresponding to the transfer voltage.
When a transfer voltage having a polarity opposite to that of the toner constituting the toner image formed on the photoconductor 12 is applied from the power source 30 of the transfer member 20 to the transfer member 20, for example, between the photoconductor 12 and the transfer member 20. In the facing area (see transfer area 32A in FIG. 1), an electric field having an electric field strength for moving each toner constituting the toner image on the photoreceptor 12 from the photoreceptor 12 to the transfer member 20 side by electrostatic force is formed. The

  The recording medium 30A (an example of a transfer medium) is accommodated, for example, in an accommodating portion (not shown), and is conveyed along the conveying path 34 by a plurality of conveying members (not shown) from the accommodating portion (in FIG. 1). Arrow B), and reaches the transfer area 32A, which is the area where the photoconductor 12 and the transfer member 20 face each other. For example, when a transfer voltage is applied to the transfer member 20, the toner image on the photoconductor 12 is transferred to the recording medium 30 </ b> A that has reached the transfer area 32 </ b> A by the electric field formed in the area. That is, for example, the toner image is transferred onto the recording medium 30A by the movement of the toner from the surface of the photoreceptor 12 to the recording medium 30A.

The cleaning device 22 is provided on the downstream side in the rotation direction of the photoconductor 12 from the transfer region 32A.
The cleaning device 22 removes the adhered matter on which the photosensitive member 12 having transferred the toner image to the recording medium 30A is also attached.
The cleaning device 22 removes deposits such as residual toner and paper dust on the photoconductor 12. Examples of the cleaning device 22 include a configuration having a plate-like member that contacts the photosensitive member 12 at a linear pressure of 10 g / cm to 150 g / cm.

The static eliminator 24 (an example of a static eliminator) is provided, for example, downstream of the cleaning device 22 in the rotation direction of the photoconductor 12.
After the toner image is transferred, the neutralization device 24 exposes the surface of the photoreceptor 12 to neutralize the charge.
Specifically, for example, the static eliminator 24 is electrically connected to a control unit 36 provided in the image forming apparatus 10, and is controlled by the control unit 36 over the entire surface (specifically, the surface of the photoreceptor 12. For example, the entire surface of the image forming area is exposed to remove electricity.

  Examples of the static eliminating device 24 include a device that irradiates a light source such as a tungsten lamp (for example, white light) and a light emitting diode (LED: for example, red light).

For example, the fixing device 26 is provided on the downstream side in the transport direction of the transport path 34 of the recording medium 30A from the transfer region 32A.
For example, the fixing device 26 fixes the toner image transferred onto the recording medium 30A.
Specifically, for example, the fixing device 26 is electrically connected to a control unit 36 provided in the image forming apparatus 10, and the toner image transferred onto the recording medium 30A is controlled by the control unit 36. Fixing to the recording medium 30A by heat or heat and pressure.

  Examples of the fixing device 26 include a known fixing device such as a heat roller fixing device and an oven fixing device.

Here, the recording medium 30 </ b> A to which the toner image is transferred by being transported along the transport path 34 and passing through the region (transfer region 32 </ b> A) where the photoconductor 12 and the transfer member 20 face each other is omitted, for example. The conveying member further reaches the installation position of the fixing device 26 along the conveying path 34, and the toner image on the recording medium 30A is fixed.
The recording medium 30A on which the image is formed by fixing the toner image is discharged to the outside of the image forming apparatus 10 by a plurality of conveyance members (not shown).
The photosensitive member 12 is charged to the charging potential by the charging device 15 again after the charge removal by the charge removal device 24.

The control unit 36 is configured to control the operation of each unit of the image forming apparatus 10.
Specifically, as shown in FIG. 2, the control unit 36 is configured as a computer, for example, a CPU (Central Processing Unit) 36A, a RAM (Random Access Memory) 36B, a ROM (Read Only Memory) 36C, a nonvolatile memory A memory 36D and an input / output interface (I / O) 36E are connected to each other via a bus 36F.
The I / O 36E includes a photosensitive member 12 (its drive motor 27), a charging device 15 (its power supply 28), a latent image forming device 16, a developing device 18 (its power supply 32), and a transfer device 31 (its power supply 30). Each part of the image forming apparatus 10 such as the static eliminating device 24 and the fixing device 26 is connected.
The CPU 36A executes, for example, a program (for example, a control program for an image forming sequence or a recovery sequence) stored in the ROM 36C or the nonvolatile memory 36D, and controls the operation of each unit of the image forming apparatus 10. The RAM 36B is used as a work memory. The ROM 36C and the non-volatile memory 36D store, for example, programs executed by the CPU 30, data necessary for processing by the CPU 30, and the like. The control program may be provided by an external recording medium such as a DVD.

Next, the process performed in the control part 36 is demonstrated.
This process will be described as a process that is executed after the image forming operation of the image forming apparatus 10 is completed.
Here, the image forming operation includes, for example, a process of charging the surface of the photoconductor 12, a process of forming an electrostatic latent image on the surface of the charged photoconductor 12, and a developer containing toner. Developing the electrostatic latent image formed on the surface of the toner, forming a toner image, transferring the toner image formed on the surface of the photoreceptor 12 to the recording medium 30A, and transferring the toner image; This is an image forming sequence for performing a step of exposing the surface of the electrophotographic photosensitive member to neutralize and a step of fixing the toner image transferred to the recording medium 30A.

First, as shown in FIG. 3, in step 200, when an image formation end instruction is received, the number of output of the same image formed continuously and the process speed of the image formation are included in the completed image formation information. Get information. Then, the process proceeds to Step 202.
Here, the “number of output of the same image formed continuously” corresponds to, for example, the number (sheets) of the recording medium 30A on which the same image is formed.
On the other hand, the “image forming process speed” corresponds to, for example, the rotational speed (mm / s) of the photoconductor 12 or the conveying speed (mm / s) of the recording medium 30A.
The image formation information is stored in the ROM 36C or the non-volatile memory 36D as print job information in addition to the image formation process in addition to the image formation process, and is acquired from the stored information.

  The image formation end instruction determines, for example, whether a signal indicating the end of image formation has been input. This determination may be made, for example, by determining that an operation panel (not shown) is operated and a signal indicating the end of image formation is input, or for a print target included in a print job to be subjected to image formation processing. You may perform by discriminating that all the printing processes of the image were completed.

Next, in step 202, it is determined whether or not the output number of the same image formed continuously and the process speed of the image formation have a predetermined relationship.
Specifically, for example, a predetermined relationship between the number of outputs of the same image formed continuously and the process speed of the image formation is expressed by the following formula (11) (preferably the following formula (11-1)). It is determined whether or not the relationship is shown.
Formula (11): OP / PS ≧ 2.2
Formula (11-1): 5.0 ≧ OP / PS ≧ 2.2
(In Expressions (11) and (11-1), OP indicates the number of sheets of the same image formed continuously (sheets), and PS indicates the process speed (mm / s) of image formation. .)

Information on this relationship is stored in advance in the ROM 36C and the nonvolatile memory 36D, and this relationship is determined based on the stored information.
The determination of this relationship is not limited to the above relationship. For example, the number of outputs of the same continuously formed image is equal to or greater than a predetermined number of outputs (for example, the number of outputs of the recording medium 30A is 1000 or more, preferably The image forming process speed may be determined based on whether or not the image forming process speed is equal to or lower than a predetermined speed (for example, 440 mm / s or lower, preferably 220 mm / s or lower).

  In step 202, if the determination is affirmed, the process proceeds to step 204, and if the determination is negative, the process is terminated.

Next, in step 204, it is determined whether or not the number of times the recovery sequence A (described later) has been continuously executed up to the immediately preceding process is nA or less. The number of continuous executions nA of the recovery sequence A may be smaller than the number of continuous executions nB of the recovery sequence B (described later) (for example, 50 or less, preferably 10 or less).
For example, the number of continuous executions of the recovery sequence A is counted and stored in the ROM 36C or the nonvolatile memory 36D each time the recovery sequence A is executed, and is determined from the count number. This count number is reset to “0” when the recovery sequence B is executed.
In step 204, if the determination is affirmed, the process proceeds to step 206, and if the determination is negative, the process proceeds to step 210.

Next, in step 206, it is determined whether or not the number of times the recovery sequence B (described later) has been continuously executed up to the immediately preceding process is nB or more. The number of continuous executions nB of the recovery sequence B is preferably a number of times (for example, 200 times or less, preferably 50 times or less) greater than the number of continuous executions nA of the recovery sequence A (described later).
For example, the number of continuous executions of the recovery sequence B is counted and stored in the ROM 36C or the nonvolatile memory 36D every time the recovery sequence A is executed, and is determined from the count number. This count is reset to “0” when the recovery sequence A is executed.
In step 206, if the determination is affirmed, the process proceeds to step 208, and if the determination is negative, the process proceeds to step 210.

Next, in step 208, the recovery sequence A is executed.
In the recovery sequence A, for example, the voltage applied at the time of completed image formation is applied to the charging member 14 and the developing member 18A, the voltage applied at the time of completed image formation is applied to the transfer member 20, and the static eliminator. With the surface of the photoconductor 12 being exposed by 24, the photoconductor 12 is rotated. This recovery sequence A is executed by controlling the drive motor 27, the power supply 28, the power supply 30, the power supply 32, and the static eliminator 24.

In the recovery sequence A, the rotation speed of the photoconductor 12 is preferably, for example, 105 rpm or more and 210 rpm or less. Further, the rotational speed of the photoconductor 12 is preferably 15 times or more and 50 times or less.
Here, in the recovery sequence A, for example, the voltage applied to the charging member 14 and the developing member 18A and the voltage applied to the transfer member 20 are opposite in polarity. Specifically, for example, the voltage applied to the charging member 14 and the developing member 18A is a negative voltage, and the voltage applied to the transfer member 20 is a positive voltage.
Further, the voltage applied to the charging member 14, the developing member 18A, and the transfer member 20 may be a DC voltage or an AC voltage. Moreover, this voltage may superimpose an AC voltage on a DC voltage.

By the recovery sequence A, the photosensitive member 12 is charged (negatively charged, positively charged) and exposed sequentially, and the charge (carrier) accumulated in the photosensitive member 12 is released.
In the recovery sequence A, a mode in which no voltage is applied to the developing member 18A may be used.

Next, in step 210, the recovery sequence B is executed.
In the recovery sequence B, for example, a voltage lower than the voltage applied during the completed image formation is applied to the charging member 14 and the developing member 18A, and a voltage higher than the voltage applied during the completed image formation is applied to the transfer member. The photoconductor 12 is rotated while being applied to the surface 20 and the surface of the photoconductor 12 is exposed by the static eliminator 24. This recovery sequence B is executed by controlling the drive motor 27, the power supply 28, the power supply 30, the power supply 32, and the static eliminator 24.

In the recovery sequence B, the rotation speed of the photoconductor 12 is preferably, for example, 105 rpm or more and 210 rpm or less. Further, the rotational speed of the photoconductor 12 is preferably 15 times or more and 50 times or less.
The voltage applied to the charging member 14 and the developing member 18A is preferably a voltage (absolute value) that is 200V or more and 500V or less lower than the voltage applied at the time of completed image formation.
The voltage applied to the transfer member 20 is preferably a voltage (absolute value) that is 200 V or more and 500 V or less higher than the voltage that was applied when the completed image was formed.
Here, in the recovery sequence B, for example, the voltage applied to the charging member 14 and the developing member 18A and the voltage applied to the transfer member 20 are opposite in polarity. Specifically, for example, the voltage applied to the charging member 14 and the developing member 18A is a negative voltage, and the voltage applied to the transfer member 20 is a positive voltage.
Further, the voltage applied to the charging member 14, the developing member 18A, and the transfer member 20 may be a DC voltage or an AC voltage. Moreover, this voltage may superimpose an AC voltage on a DC voltage.

By the recovery sequence B, the photosensitive member 12 is charged (negatively charged, positively charged) and exposed sequentially, and the charge (carrier) accumulated in the photosensitive member 12 is released.
In the recovery sequence B, the voltage may not be applied to the developing member 18A.

  Then, after executing the recovery sequence A or B, this process is terminated.

In the image forming apparatus 10 according to the present embodiment described above, the electron-accepting compound (an electron-accepting compound having an anthraquinone structure) represented by the general formula (1-1) and the following general formula (1-2) is selected. A photosensitive member 12 having an undercoat layer containing at least one kind.
After the image formation is completed, when the output number of the same image formed continuously and the process speed of the image formation in the completed image formation information have a predetermined relationship, the charging member 14 and the transfer member 20 And a controller 36 that executes a recovery sequence for rotating the photoconductor 12 while the surface of the photoconductor 12 is exposed by the static eliminator 24. The control unit 36 controls the drive motor 27, the power source 28, the power source 30, the power source 32, and the static eliminator 24, and executes this recovery sequence.
With this configuration, in the image forming apparatus 10 according to the present embodiment, an image in which ghost (density change due to the history of the previous cycle) is suppressed can be obtained.

Here, conventionally, there has been known a technique for suppressing generation of a residual potential of the photoreceptor 12 by blending an electron accepting compound (particularly, an electron accepting compound having an anthraquinone structure) into the undercoat layer.
However, when an electron-accepting compound is added to the undercoat layer, the energy barrier at the interface between the undercoat layer and the photosensitive layer (for example, the charge generation layer) is reduced, and charges (carriers) accumulated at the interface are reduced to the photosensitive layer (for example, the charge layer). It is considered that it easily passes through the generation layer and the charge transport layer) and reaches the outermost surface of the photoreceptor 12. That is, charges (carriers) accumulated at the interface between the undercoat layer and the photosensitive layer (for example, the charge generation layer) distort the internal electric field around the interface, creating a local high electric field, and charge blocking ( It is considered that the carrier blocking property is likely to be lowered. As a result, the potential of the charged portion (for example, the non-exposed portion by the latent image forming apparatus) on the surface of the electrophotographic photosensitive member is lowered, and the density change due to the history of the previous cycle (specifically, the image forming history portion of the previous cycle follows It is considered that a phenomenon (ghost) that image density decreases in a cycle is likely to occur.
In particular, when the same image is output continuously, the accumulated charges (accumulated carriers) increase in proportion to the number of outputs, and thus the above phenomenon (ghost) is also conspicuous. Further, since the accumulated charge (accumulated carrier) increases in proportion to a decrease in the process speed of image formation, it is considered that the above phenomenon (ghost) also occurs remarkably.

On the other hand, in the image forming apparatus 10 according to the present embodiment, the accumulated charge (accumulated carrier) increases after the image formation is completed. “The number of output of the same image formed continuously and the process speed of the image formation” Is a predetermined relationship ”, the controller 36 executes the recovery sequence. As a result, even if the photoreceptor 12 having the undercoat layer containing the electron-accepting compound having an anthraquinone structure is provided, after the image formation is completed, the photoreceptor 12 is charged (negatively charged, positively charged), and the exposure is sequentially performed. Charges (carriers) accumulated in the photoconductor 12 are released.
For this reason, in the image forming apparatus 10 according to the present embodiment, an image in which ghost is suppressed can be obtained.

In the image forming apparatus 10 according to the present embodiment, the control unit 36 executes the recovery sequences A and B as the recovery sequence. Specifically, for example, the recovery sequences A and B are selectively executed according to the number of continuous executions of each recovery sequence.
The recovery sequence A has a higher charge (carrier) release ability than the recovery sequence B, but the wear of the photoconductor 12 tends to be promoted. For this reason, when the recovery sequence A is executed, an image in which ghost is suppressed is easily obtained.
The recovery sequence B has a lower charge (carrier) release ability than the recovery sequence A, but the wear of the photoconductor 12 tends to be reduced. For this reason, when the recovery sequence B is executed, wear of the photoconductor 12 is easily suppressed.
Therefore, it is preferable that the recovery sequences A and B are selectively executed so that the recovery sequence B is larger than the recovery sequence A from the viewpoint of suppressing wear of the photosensitive member 12. Specifically, for example, each recovery sequence may be selectively executed at a rate of one recovery sequence A with respect to three recovery sequences B.

  In the image forming apparatus 10 according to the present embodiment, when a voltage is also applied to the developing member 18A in the recovery sequences A and B, toner adhesion to the electrophotographic photosensitive member during the recovery sequences A and B is suppressed. . this is. This is because an excessively large potential difference between the charging member 14 and the developing member 18A is suppressed.

  In the image forming apparatus 10 according to this embodiment, the control unit 36 selectively performs the recovery sequences A and B. However, the present invention is not limited to this, and one of the recovery sequences A and B is executed. An aspect may be sufficient.

[Photoconductor]
Next, details of the photoreceptor 12 provided in the image forming apparatus 10 according to the present embodiment will be described with reference to the drawings.
4 to 9 are schematic views showing examples of the layer structure of the photoreceptor according to this embodiment.

The photoreceptor shown in FIG. 4 includes a conductive substrate 1, an undercoat layer 2 formed on the conductive substrate 1, and a photosensitive layer 3 formed on the undercoat layer 2. .
Further, as shown in FIG. 5, the photosensitive layer 3 may have a two-layer structure of a charge generation layer 3A and a charge transport layer 3B. Furthermore, as shown in FIGS. 6 and 7, a protective layer 5 may be provided on the photosensitive layer 3 or the charge transport layer 3B. 8 and 9, an intermediate layer 4 may be provided between the undercoat layer 2 and the photosensitive layer 3 or between the undercoat layer 2 and the charge generation layer 3A.

  In addition, although the intermediate layer 4 shows the aspect provided between the undercoat layer 2 and the photosensitive layer 3 or between the undercoat layer 2 and the charge generation layer 3A, the conductive substrate 1 and the undercoat layer 2 are shown. You may provide between. Of course, the aspect which does not provide the intermediate | middle layer 4 may be sufficient.

  Next, each element of the photoreceptor 12 will be described. Note that the reference numerals are omitted.

-Conductive substrate-
Any conductive substrate may be used as long as it is conventionally used. For example, thin films (eg, metals such as aluminum, nickel, chromium, stainless steel, and films of aluminum, titanium, nickel, chromium, stainless steel, gold, vanadium, tin oxide, indium oxide, indium tin oxide (ITO), etc.) And a plastic film coated or impregnated with a conductivity-imparting agent, a plastic film coated or impregnated with a conductivity-imparting agent, and the like. The shape of the substrate is not limited to a cylindrical shape, and may be a sheet shape or a plate shape.

  When a metal pipe is used as the conductive substrate, the surface may be left as it is, and processing such as mirror cutting, etching, anodic oxidation, rough cutting, centerless grinding, sand blasting, wet honing has been performed in advance. Also good.

-Undercoat layer-
The undercoat layer includes a binder resin, metal oxide particles, and an electron accepting compound.

-Binder resin As the binder resin, for example, acetal resin (for example, polyvinyl butyral), polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride Examples thereof include polymer resin compounds such as resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-alkyd resins, phenol resins, phenol-formaldehyde resins, and melamine resins. Moreover, the resin obtained by reaction of these resin and a hardening | curing agent is also mentioned.

Metal oxide particles Examples of the metal oxide particles include antimony oxide, indium oxide, tin oxide, titanium oxide, and zinc oxide.
Among these, as the metal oxide particles, tin oxide, titanium oxide, and zinc oxide particles are preferable from the viewpoint of fine line reproducibility and suppression of increase in residual voltage.

As the metal oxide particles, a conductive powder having a particle size of 100 nm or less, particularly 10 nm or more and 100 nm or less is preferably used. The particle size here means an average primary particle size. The average primary particle size of the metal oxide particles is a value observed and measured by SEM (scanning electron microscope).
When the particle diameter of the metal oxide particles is 10 nm or less, the surface area of the metal oxide particles is increased, and the uniformity of the dispersion may be reduced. On the other hand, when the particle size of the metal oxide particles exceeds 100 nm, the secondary particles or higher particles are expected to have a particle size of about 1 μm, and the portion where the metal oxide particles exist in the undercoat layer. A part that does not exist, that is, a so-called sea-island structure tends to be formed, and image quality defects such as non-uniform halftone density may occur.

The metal oxide particles preferably have a powder resistance of 10 ⁴ Ω · cm to 10 ¹⁰ Ω · cm. As a result, it becomes easy for the undercoat layer to obtain an appropriate impedance at a frequency corresponding to the electrophotographic process speed.
If the resistance value of the metal oxide particles is lower than 10 ⁴ Ω · cm, the slope of the dependency of the impedance on the particle addition amount is too large, and it may be difficult to control the impedance. On the other hand, if the resistance value of the metal oxide particles is higher than 10 ¹⁰ Ω · cm, the residual potential may be increased.

The metal oxide particles may be surface-treated with at least one coupling agent for the purpose of improving various properties such as dispersibility, if necessary.
The coupling agent may be at least one selected from silane coupling agents, titanate coupling agents, and aluminate coupling agents.
Specific examples of the coupling agent include vinyltrimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and 3-glycid. Xylpropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (amino Silane coupling agents such as ethyl) -3-aminopropylmethyldimethoxysilane, N, N-bis (2-hydroxyethyl) -3-aminopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, acetoalkoxyaluminum diisopropyl Rate etc. Examples include aluminate coupling agents, isopropyl triisostearoyl titanate, bis (dioctyl pyrophosphate), titanate coupling agents such as isopropyl tri (N-aminoethyl-aminoethyl) titanate, and the like. It is not something. Moreover, you may use these coupling agents in mixture of 2 or more types.

  The treatment amount of the coupling agent is preferably 0.1% by mass or more and 3% by mass or less, more preferably 0.3% by mass or more and 2.0% by mass or less, more preferably, based on the metal oxide particles. It is 0.5 mass% or more and 1.5 mass% or less.

In addition, the processing amount of a coupling agent is measured as follows.
There are analysis methods such as FT-IR method, 29Si solid state NMR method, thermal analysis, XPS, etc., but FT-IR method is the simplest. In the FT-IR method, the normal KBr tablet method or the ATR method may be used. A small amount of the treated metal oxide particles are mixed with KBr and the FT-IR is measured to measure the throughput of the coupling agent.

  The metal oxide particles may be subjected to a heat treatment after the surface treatment with the above-described coupling agent to improve the environmental dependency of the resistance value, if necessary. The heat treatment temperature is preferably, for example, 150 ° C. or more and 300 ° C. or less, and the treatment time is 30 minutes or more and 5 hours or less.

  The content of the metal oxide particles is desirably 30% by mass or more and 60% by mass or less, and more desirably 35% by mass or more and 55% by mass or less from the viewpoint of maintaining electric characteristics.

-Electron-accepting compound The electron-accepting compound is a material that chemically reacts with the surface of the metal oxide particles contained in the undercoat layer or a material that adsorbs to the surface of the metal oxide particles. May be present selectively.

  As the electron-accepting compound, at least one selected from electron-accepting compounds represented by general formula (1-1) and the following general formula (1-2) (electron-accepting compounds having an anthraquinone structure) is applied. The

In general formula (1-1) and general formula (1-2), n11, n11 ′, n12, n12 ′, n13, and n14 each independently represents an integer of 0 or more and 3 or less. However, at least one of n11 and n12 represents an integer of 1 or more and 3 or less (that is, n11 and n12 do not simultaneously represent 0). At least one of n11 ′ and n12 ′ represents an integer of 1 or more and 3 or less (that is, n11 ′ and n12 ′ do not simultaneously represent 0). At least one of n14 and n13 represents an integer of 1 or more and 3 or less (that is, n14 and n13 do not simultaneously represent 0). m11, m11′m12 and m12 ′ each independently represents an integer of 0 or 1. r11 represents an integer of 2 or more and 10 or less. R ¹¹ , R ^{11 ′} , R ¹² and R ^{12 ′} each independently represent an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms.

In general formula (1-1) and general formula (1-2), the alkyl group having 1 to 10 carbon atoms represented by R ¹¹ , R ^{11 ′} , R ¹² and R ^{12 ′} is linear or Any of a chain may be used, and examples thereof include a methyl group, an ethyl group, a propyl group, and an isopropyl group. The alkyl group having 1 to 10 carbon atoms is preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms.
The alkoxy group (alkoxyl group) having 1 to 10 carbon atoms represented by R ¹¹ , R ^{11 ′} , R ¹² and R ^{12 ′} may be either linear or branched, for example, methoxy group, ethoxy Group, propoxy group, isopropoxy group and the like. The alkoxy group having 1 to 10 carbon atoms is preferably an alkoxyl group having 1 to 8 carbon atoms, more preferably an alkoxyl group having 1 to 6 carbon atoms.

  Specific examples of the electron-accepting compound are shown below, but are not limited thereto.

In addition, with the electron-accepting compound (electron-accepting compound which has an anthraquinone structure) shown by the general formula (1-1) and the following general formula (1-2). Other electron-accepting compounds may be used in combination.
Examples of other electron-accepting compounds include quinone, coumarin, phthalocyanine, triphenylmethane, anthocyanin, flavone, fullerene, ruthenium complex, xanthene, benzoxazine, and porphyrin materials.
When other electron-accepting compounds are used in combination, the proportion of the electron-accepting compound represented by the general formula (1-1) and the following general formula (1-2) in the total electron-accepting compound is 50% by mass or more. It is preferably 75% by mass or more.

The content of the electron-accepting compound is determined from the surface area and content of the metal oxide particles of the metal oxide particles that are the chemical reaction or adsorption partner, and the electron transport ability of each material, but is usually 0.1 mass. % To 20% by mass, more desirably 0.5% to 10% by mass.
If the content of the electron-accepting compound is 0.1% by mass or less, the effect of the acceptor substance may be difficult to express. Conversely, if the content of the electron-accepting compound exceeds 20% by mass, the metal oxide particles tend to agglomerate, and the metal oxide particles tend to be non-uniformly distributed in the undercoat layer, resulting in good conductivity. It may be difficult to form a path. For this reason, the residual potential rises and not only ghosts are generated, but also black spots and halftone density non-uniformity may occur.

Other additives include resin particles. When coherent light such as a laser is used for the exposure apparatus, it is preferable to prevent moiré images. for that purpose. The surface roughness of the undercoat layer is preferably adjusted to ¼n (n is the refractive index of the upper layer) or more and ½λ or less of the exposure laser wavelength λ to be used. Therefore, when the resin particles are added to the undercoat layer, the surface roughness can be adjusted. Examples of the resin particles include silicone resin particles and cross-linked polymethyl methacrylate (PMMA) resin.
Further, the other additives are not limited to the above, and well-known additives are also included.

In forming the undercoat layer, an undercoat layer forming coating solution in which the above components are added to a solvent is used. The coating liquid for forming the undercoat layer can be obtained, for example, by dispersing a premixed or predispersed metal oxide particle and, if necessary, an electron accepting compound or other additives in a binder resin.
The solvent used for obtaining the coating solution for forming the undercoat layer is a known organic solvent that dissolves the binder resin described above, for example, alcohol, aromatic, halogenated hydrocarbon, ketone, ketone alcohol, ether. And ester solvents. These solvents may be used alone or in combination of two or more.
As a method of dispersing the metal oxide particles in the undercoat layer forming coating solution, a known dispersion method is used. Examples thereof include a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, and a paint shaker.

  As a coating method for the coating solution for forming the undercoat layer, known coating methods such as a dip coating method, a blade coating method, a wire bar coating method, a spray coating method, a bead coating method, an air knife coating method, and a curtain coating method are used.

  The undercoat layer preferably has a Vickers strength of 35 to 50.

  The thickness of the undercoat layer is preferably 15 μm or more, more preferably 15 μm or more and 30 μm or less, and further preferably 20 μm or more and 25 μm or less from the viewpoint of improving the graininess of the image.

-Intermediate layer-
The intermediate layer is provided as necessary between the undercoat layer and the photosensitive layer, for example, in order to improve electrical characteristics, improve image quality, improve image quality maintenance, and improve photosensitive layer adhesion. The intermediate layer may be provided between the conductive substrate and the undercoat layer.

  As the binder resin used for the intermediate layer, acetal resin (for example, polyvinyl butyral), polyvinyl alcohol resin, casein, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin In addition to polymer resin compounds such as polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, melamine resin, zirconium, titanium, aluminum, manganese, silicon And organometallic compounds containing atoms. These compounds may be used alone or as a mixture or polycondensate of a plurality of compounds. Among them, an organometallic compound containing zirconium or silicon is preferable in that it has a low residual potential, a small potential change due to the environment, and a small potential change due to repeated use.

In forming the intermediate layer, a coating solution for forming an intermediate layer in which the above components are added to a solvent is used.
As the coating method for forming the intermediate layer, usual methods such as a dip coating method, a push-up coating method, a wire bar coating method, a spray coating method, a blade coating method, a knife coating method, and a curtain coating method are used.

  In addition to improving the coatability of the upper layer, the intermediate layer also serves as an electrical blocking layer. However, if the film thickness is too large, the electrical barrier becomes too strong and the potential increases due to desensitization or repetition. May cause. Therefore, when forming the intermediate layer, it is preferable to set the film thickness within the range of 0.1 μm to 3 μm. In this case, the intermediate layer may be used as the undercoat layer.

-Charge generation layer-
The charge generation layer includes, for example, a charge generation material and a binder resin. The charge generation layer may be composed of a vapor deposition film of a charge generation material.
Examples of the charge generation material include phthalocyanine pigments such as metal-free phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, dichlorotin phthalocyanine, and titanyl phthalocyanine. Chlorogallium phthalocyanine crystal having strong diffraction peaks at least at 7.4 °, 16.6 °, 25.5 ° and 28.3 °, Bragg angle (2θ ± 0.2 °) to CuKα characteristic X-ray of at least 7. Metal-free phthalocyanine crystals having strong diffraction peaks at 7 °, 9.3 °, 16.9 °, 17.5 °, 22.4 ° and 28.8 °, Bragg angle (2θ ± 0. 2 °) at least 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, 25 Hydroxygallium phthalocyanine crystals having strong diffraction peaks at 1 ° and 28.3 °, Bragg angles (2θ ± 0.2 °) with respect to CuKα characteristic X-rays of at least 9.6 °, 24.1 ° and 27.2 ° A titanyl phthalocyanine crystal having a strong diffraction peak can be mentioned. In addition, examples of the charge generation material include quinone pigments, perylene pigments, indigo pigments, bisbenzimidazole pigments, anthrone pigments, quinacridone pigments, and the like. These charge generation materials may be used alone or in combination of two or more.

  Examples of the binder resin constituting the charge generation layer include polycarbonate resin such as bisphenol A type or bisphenol Z type, acrylic resin, methacrylic resin, polyarylate resin, polyester resin, polyvinyl chloride resin, polystyrene resin, acrylonitrile-styrene. Copolymer resin, acrylonitrile-butadiene copolymer, polyvinyl acetate resin, polyvinyl formal resin, polysulfone resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride Examples thereof include resins, silicone resins, phenol-formaldehyde resins, polyacrylamide resins, polyamide resins, poly-N-vinylcarbazole resins. These binder resins may be used alone or in combination of two or more.

  The mixing ratio of the charge generating material and the binder resin is preferably in the range of 10: 1 to 1:10, for example.

When forming the charge generation layer, a coating solution for forming a charge generation layer in which the above components are added to a solvent is used.
As a method for dispersing particles (for example, charge generation material) in the coating solution for forming the charge generation layer, a media dispersion machine such as a ball mill, a vibration ball mill, an attritor, a sand mill, a horizontal sand mill, an agitation, an ultrasonic dispersion machine, a roll mill, etc. Medialess dispersers such as high-pressure homogenizers are used. Examples of the high-pressure homogenizer include a collision method in which the dispersion liquid is dispersed by liquid-liquid collision or liquid-wall collision in a high-pressure state, and a penetration method in which a fine flow path is dispersed in a high-pressure state.

  Examples of the method for applying the charge generation layer forming coating liquid on the undercoat layer include dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating. It is done.

  The thickness of the charge generation layer is desirably set in the range of 0.01 μm to 5 μm, more desirably 0.05 μm to 2.0 μm.

-Charge transport layer-
The charge transport layer includes a charge transport material and, if necessary, a binder resin.
Examples of the charge transport material include oxadiazole derivatives such as 2,5-bis (p-diethylaminophenyl) -1,3,4-oxadiazole, 1,3,5-triphenyl-pyrazoline, 1- [ Pyrazoline derivatives such as pyridyl- (2)]-3- (p-diethylaminostyryl) -5- (p-diethylaminostyryl) pyrazoline, triphenylamine, N, N′-bis (3,4-dimethylphenyl) biphenyl- Aromatic tertiary amino compounds such as 4-amine, tri (p-methylphenyl) aminyl-4-amine, dibenzylaniline, N, N′-bis (3-methylphenyl) -N, N′-diphenylbenzidine Aromatic tertiary diamino compounds such as 3- (4'-dimethylaminophenyl) -5,6-di- (4'-methoxyphenyl) -1,2,4 1,2,4-triazine derivatives such as triazine, hydrazone derivatives such as 4-diethylaminobenzaldehyde-1,1-diphenylhydrazone, quinazoline derivatives such as 2-phenyl-4-styryl-quinazoline, 6-hydroxy-2,3- Benzofuran derivatives such as di (p-methoxyphenyl) benzofuran, α-stilbene derivatives such as p- (2,2-diphenylvinyl) -N, N-diphenylaniline, enamine derivatives, carbazole derivatives such as N-ethylcarbazole, poly -Hole transport materials such as -N-vinylcarbazole and its derivatives, quinone compounds such as chloranil and broanthraquinone, tetraanoquinodimethane compounds, 2,4,7-trinitrofluorenone, 2,4,5,7 -Fluorenone such as tetranitro-9-fluorenone Examples thereof include an electron transport material such as a compound, a xanthone compound, and a thiophene compound, and a polymer having a group consisting of the above-described compounds in a main chain or a side chain. These charge transport materials may be used alone or in combination of two or more.

Examples of the binder resin constituting the charge transport layer include polycarbonate resin such as bisphenol A type or bisphenol Z type, acrylic resin, methacrylic resin, polyarylate resin, polyester resin, polyvinyl chloride resin, polystyrene resin, acrylonitrile-styrene. Copolymer resin, acrylonitrile-butadiene copolymer resin, polyvinyl acetate resin, polyvinyl formal resin, polysulfone resin, styrene-butadiene copolymer resin, vinylidene chloride-acrylonitrile copolymer resin, vinyl chloride-vinyl acetate-anhydrous maleic acid Insulating resins such as acid resins, silicone resins, phenol-formaldehyde resins, polyacrylamide resins, polyamide resins, chlorinated rubber, and polyvinylcarbazole and polyvinylanthra Emissions, organic photoconductive polymers such as polyvinyl pyrene, and the like. These binder resins may be used alone or in combination of two or more.
The mixing ratio between the charge transport material and the binder resin is preferably 10: 1 to 1: 5, for example.

  In particular, as the charge transport layer, a polycarbonate copolymer comprising a charge transport material represented by the general formula (2), a repeating unit represented by the general formula (3), and a repeating unit represented by the following general formula (4): It is preferable that the composition (hereinafter referred to as “specific polycarbonate copolymer”) is included. The charge transport layer having this configuration increases the mobility of charges and makes it easy to obtain an image in which ghosts are suppressed.

In the general formula (2), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ may be the same or different and each represents a hydrogen atom, an alkyl group, an alkoxyl group, a halogen An atom or a substituted or unsubstituted aryl group is shown. m1 and n2 each independently represent 0 or 1.

Of the groups represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ in general formula (2), the alkyl group is preferably an alkyl group having 1 to 20 carbon atoms. The alkoxyl group is preferably an alkoxyl group having 1 to 20 carbon atoms. Examples of the substituent for substituting the aryl group include a halogen atom, an alkoxyl group, an alkyl group, and an aryl group.

In general formula (2), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are preferably a hydrogen atom, an alkyl group, or an alkoxyl group, among which hydrogen atom, carbon An alkyl group having 1 to 3 carbon atoms or an alkoxyl group having 1 to 3 carbon atoms is desirable.

  In general formula (2), m1 is preferably 1, and n2 is preferably 1.

  Specific examples of the charge transport material represented by the general formula (2) are shown below, but are not limited thereto.

In General Formula (3) and General Formula (4), R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, or a carbon number. It represents a cycloalkyl group having 5 to 7 carbon atoms or an aryl group having 6 to 12 carbon atoms.
R ⁷ , R ⁸ , R ⁹ , and R ¹⁰ preferably represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 12 carbon atoms. It is desirable to indicate a group.
X represents a phenylene group, a biphenylene group, a naphthylene group, a linear or branched alkylene group (desirably 1 to 12 carbon atoms), or a cycloalkylene group (desirably 3 to 12 carbon atoms).

  In the specific polycarbonate copolymer, the repeating unit represented by the general formula (3), the repeating unit represented by the general formula (4), and the copolymerization ratio (corresponding to the m: n ratio in the following specific examples) are For example, m: n = 95: 5 to 5:95, 50:50 to 5:95, and 30:70 to 10:90.

  The specific polycarbonate copolymer is synthesized by a method such as polycondensation with a carbonate-forming compound such as phosgene or transesterification with bisaryl carbonate, using raw materials such as 4,4'-dihydroxybiphenyl compound. To do.

  As a viscosity average molecular weight of a specific polycarbonate copolymer, 20000 or more and 100000 or less are mentioned, for example, 30000 or more and 80000 or less may be sufficient, and 40000 or more and 70000 or less may be sufficient.

  Although the specific example of a specific polycarbonate copolymer is illustrated, it is not limited to these.

The charge transport layer is formed using a charge transport layer forming coating solution in which the above components are added to a solvent.
As a method for applying the charge transport layer forming coating solution on the charge generation layer, dip coating method, push-up coating method, wire bar coating method, spray coating method, blade coating method, knife coating method, curtain coating method, etc. The method is used.

  The film thickness of the charge transport layer is desirably set in the range of 5 μm to 50 μm, more desirably 10 μm to 40 μm.

(Protective layer)
The protective layer is provided on the photosensitive layer as necessary. For example, in the case of a photoreceptor having a laminated structure, the protective layer is provided to prevent chemical change of the charge transport layer during charging or to further improve the mechanical strength of the photosensitive layer.
Therefore, it is preferable to apply a layer that includes a crosslinked product (cured product) as the protective layer. Examples of these layers include known configurations such as a cured layer of a composition containing a reactive charge transport material and, if necessary, a curable resin, and a cured layer in which the charge transport material is dispersed in the curable resin. . The protective layer may be a layer in which a charge transport material is dispersed in a binder resin.

A protective layer is formed using the coating liquid for protective layer formation which added the said component to the solvent.
As a method for applying the coating liquid for forming the protective layer on the charge generation layer, the usual methods such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, knife coating, and curtain coating are used. The method is used.

  The thickness of the protective layer is 1 μm or more and 20 μm or less, preferably 2 μm or more and 10 μm or less.

(Single layer type photosensitive layer)
The single-layer type photosensitive layer (charge generation / charge transport layer) includes, for example, a binder resin, a charge generation material, and a charge transport material. These materials are the same as those described in the charge generation layer and the charge transport layer.
In the single-layer type photosensitive layer, the content of the charge generating material is desirably about 10% by mass to 85% by mass, and more desirably 20% by mass to 50% by mass. In addition, the content of the charge transport material is desirably 5% by mass or more and 50% by mass or less.
The method for forming the single-layer type photosensitive layer is the same as the method for forming the charge generation layer and the charge transport layer. The thickness of the single-layer photosensitive layer is preferably about 5 μm to 50 μm, and more preferably 10 μm to 40 μm.

(Other)
In the electrophotographic photoreceptor according to the exemplary embodiment, the photosensitive layer and the protective layer are formed in the photosensitive layer for the purpose of preventing degradation of the photoreceptor due to ozone, oxidizing gas, or light / heat generated in the image forming apparatus. Additives such as antioxidants, light stabilizers, heat stabilizers and the like may be added.
Further, at least one electron accepting substance may be added to the photosensitive layer and the protective layer for the purpose of improving sensitivity, reducing residual potential, and reducing fatigue during repeated use.
Further, in the photosensitive layer and the protective layer, silicone oil may be added as a leveling agent to the coating solution for forming each layer to improve the smoothness of the coating film.

  Note that the image forming apparatus 10 according to the present embodiment is not limited to the above-described configuration. For example, an intermediate transfer in which a toner image formed on the photoconductor 12 is transferred to the intermediate transfer member and then transferred to the recording medium 30A. An image forming apparatus of a system may be employed, or an image forming apparatus of a tandem system may be employed. Here, in the case of an intermediate transfer type image forming apparatus, the intermediate transfer member corresponds to an example of a transfer target, and the primary transfer member corresponds to an example of a transfer member.

  Hereinafter, the image forming apparatus of the present embodiment will be specifically described with reference to examples, but the present invention is not limited to these examples. Further, unless otherwise specified, “part” represents “part by mass” and “%” represents “mass%”.

[Production of photoconductor]
(Photoreceptor 1)
100 parts by mass of zinc oxide (average particle size: 70 nm, manufactured by Teica, specific surface area value: 15 m ² / g) was stirred and mixed with 500 parts by mass of methanol, and KBM603 (manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent. 75 parts by mass was added and stirred for 2 hours. Thereafter, methanol was distilled off under reduced pressure, and baking was performed at 120 ° C. for 3 hours to obtain silane coupling agent surface-treated zinc oxide particles.

60 parts by mass of the zinc oxide particles subjected to the surface treatment, 1.2 parts by mass of the exemplary compound (1-6) as the specific electron accepting compound, and blocked isocyanate (Sumidule 3173, Sumitomo Bayern urethane as the curing agent) 13.5 parts by mass), 15 parts by mass of butyral resin (ESREC BM-1, manufactured by Sekisui Chemical Co., Ltd.), 38 parts by mass of a solution dissolved in 85 parts by mass of methyl ethyl ketone, and 25 parts by mass of methyl ethyl ketone Then, dispersion was performed for 4 hours using a glass mill having a diameter of 1 mm in a sand mill. To the obtained dispersion, 0.005 parts by mass of dioctyltin dilaurate and 4.0 parts by mass of silicone resin particles (Tospearl 145, manufactured by GE Toshiba Silicone) are added as a catalyst, and a coating liquid for forming an undercoat layer is added. Obtained. The viscosity of the coating solution for forming the undercoat layer at the coating temperature (24 ° C.) was 235 mPa · s.
This coating solution was applied onto an aluminum substrate having a diameter of 40 mm at a coating speed of 220 mm / min by a dip coating method, followed by drying and curing at 180 ° C. for 40 minutes to obtain a subbing layer having a thickness of 24 μm.

  Next, as a charge generation material, at least 7.5 °, 9.9 °, 12.5 °, 16.3 °, 18.6 °, Bragg angle (2θ ± 0.2 °) with respect to CuKα characteristic X-ray, 15 parts by mass of hydroxygallium phthalocyanine crystals having strong diffraction peaks at 25.1 ° and 28.3 °, 10 parts by mass of vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Union Carbide) and n-butyl alcohol A mixture of 300 parts by mass was dispersed for 4 hours with a sand mill using glass beads having a diameter of 1 mm to obtain a coating solution for forming a charge generation layer. The viscosity at the coating temperature (24 ° C.) of the coating solution for forming a charge generation layer was 1.8 mPa · s. This coating solution was dip-coated on the undercoat layer by a dip coating method at a coating speed of 65 mm / min and dried at 150 ° C. for 10 minutes to obtain a charge generation layer.

Next, 8 parts by mass of tetrafluoroethylene resin particles (average particle size: 0.2 μm) and 0.01 parts by mass of a fluorinated alkyl group-containing methacrylic copolymer (weight average molecular weight 30000), 4 parts by mass of tetrahydrofuran, toluene The mixture was kept at a liquid temperature of 20 ° C. together with 1 part by mass and stirred for 48 hours to obtain a tetrafluoroethylene resin particle suspension A.
Next, a compound having the following structural formula 1 as a charge transporting material (in general formula (2), n2 = 1, m1 = 1, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ are all Polycarbonate composed of repeating units of the following structural formula 2 and the following structural formula 3 with 4 parts by mass of H, tris [4- (4,4-diphenyl-1,3-butadienyl) phenyl] amine) as a binder resin 6 parts by mass of a copolymer (exemplary compound represented by structural formula (A3): viscosity average molecular weight 40000) and 0.1 part by mass of 2,6-di-t-butyl-4-methylphenol as an antioxidant were mixed. Then, 24 parts by mass of tetrahydrofuran and 11 parts by mass of toluene were mixed and dissolved to obtain a mixed solution B.
After adding the tetrafluoroethylene resin particle suspension A to this mixed solution B and stirring and mixing it, using a high-pressure homogenizer (manufactured by Yoshida Kikai Kogyo Co., Ltd.) equipped with a through-type chamber having fine flow paths. , 5 ppm of fluorine-modified silicone oil (trade name: FL-100, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to the liquid obtained by repeating the dispersion treatment with the pressure increased to 500 kgf / cm ² six times, and the charge transport layer was sufficiently stirred. A forming coating solution was obtained. This coating solution was applied on the charge generation layer to a thickness of 24 μm and dried at 135 ° C. for 25 minutes to form a charge transport layer.

  The target electrophotographic photosensitive member was obtained through the above steps. The electrophotographic photoreceptor thus obtained was designated as photoreceptor 1.

(Photoreceptor 2)
A target electrophotographic photosensitive member was obtained in the same manner as in the photosensitive member 1 except that no electron-accepting compound was used in the formation of the undercoat layer. The electrophotographic photoreceptor thus obtained was designated as photoreceptor 2.

(Photoreceptor 3)
The target electrophotographic photosensitive member was obtained in the same manner as the photosensitive member 1 except that the exemplified compound (1-1) was used as the electron-accepting compound in the formation of the undercoat layer. The electrophotographic photoreceptor thus obtained was designated as photoreceptor 3.

(Photoreceptor 4)
In the formation of the charge transport layer, the target electrophotographic photoreceptor was obtained in the same manner as the photoreceptor 1, except that the exemplified compound (2-2) was used as the charge transport material. The electrophotographic photoreceptor thus obtained was designated as photoreceptor 4.

[Examples 1-7, Comparative Examples 1-2]
The photoreceptor according to Table 1 was mounted on “700 Digital Color Press” manufactured by Fuji Xerox as an image forming apparatus. This image forming apparatus has been modified to vary the charging voltage applied to the charging member 14, the voltage applied to the developing member 18A, and the voltage applied to the transfer member 20.
This image forming apparatus continuously outputs the same image (a band image having a width of 2 mm, a length of 200 mm, and an image density of 60%) on A4 size paper under the conditions in accordance with Table 1.
After the image formation, a recovery sequence according to Table 1 was executed. And the following evaluation was performed.

-Evaluation of ghost-
The evaluation of the ghost is performed after executing the recovery sequence (in Comparative Example 1 after continuous output of the same image), and an entire halftone image with an image density of 30% on an A4 size paper in an ambient environment of 28 ° C. and 85 RH%. Output. The change in density on the halftone image was visually evaluated.
◎: Not generated ○: Small density change occurred △: Density change occurred ×: Significant density change occurred

-Amount of photoconductor wear-
For the evaluation of the wear amount, after the continuous output of the same image and the operation of executing the recovery sequence after the end of the image formation are repeated 20000 times (however, in Comparative Example 1 after the continuous output of the same image is repeated 20000 times), Using an eddy current film thickness measuring device (Fischer Instruments), measure the film thickness of the photoconductor, determine the difference (μm) from the pre-measured film thickness of the photoconductor, and wear resistance. It was used as an index.
A: <1 μm
○: 1 μm to 3 μm
Δ:> 3 μm

From the above results, it can be seen that the occurrence of ghosts is suppressed in this example.
In addition, it can be seen that Example 1 or the like in which the recovery sequence A is executed has a better ghost evaluation result than the Example 2 or the like in which the recovery sequence B is executed.
In addition, it can be seen that Example 2 or the like in which the recovery sequence B was executed gave better results for the evaluation of the wear amount of the photoconductor than the Example 1 or the like in which the recovery sequence A was executed.

  In Example 1, after the recovery sequence A was performed, the surface of the photoreceptor was observed, and no adhesion of the developer (toner) was observed, but recovery was performed without applying a voltage to the developing member. When sequence A was executed, it was confirmed that developer (toner) was adhered to the surface of the photoreceptor.

DESCRIPTION OF SYMBOLS 10 Image forming device, 12 Photoconductor, 14 Charging member, 16 Latent image forming device, 18A Developing member, 20 Transfer member, 24 Static elimination device, 26 Fixing device, 27 Drive motor, 28 Power source, 30 Power source, 32 Power source, 36 Control Part

Claims (15)

From a conductive substrate, a binder resin, metal oxide particles, and an electron-accepting compound represented by the following general formula (1-1) and the following general formula (1-2) provided on the conductive substrate An electrophotographic photoreceptor having an undercoat layer containing at least one selected, and a photosensitive layer provided on the undercoat layer,
A drive unit for rotationally driving the electrophotographic photosensitive member;
A charging member for charging the surface of the electrophotographic photosensitive member;
A voltage application unit for a charging member for applying a voltage to the charging member;
A latent image forming unit that forms an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
A developing member that develops the electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a developer containing toner to form a toner image;
A voltage applying unit for the developing member for applying a voltage to the developing member;
A transfer member for transferring a toner image formed on the surface of the electrophotographic photosensitive member to a transfer target;
A voltage applying unit for the transfer member that applies a voltage to the transfer member;
After transferring the toner image, a charge removing unit that exposes the surface of the electrophotographic photosensitive member to remove charge;
After the image formation is completed, when the output number of the same image continuously formed and the process speed of the image formation have a predetermined relationship among the completed image formation information, the voltage is applied to the charging member and the transfer member. And the drive unit, the voltage applying unit for the charging member, and the transfer member for rotating the electrophotographic photosensitive member in a state where the surface of the electrophotographic photosensitive member is exposed by the charge eliminating unit. A voltage application unit, and a control unit for controlling the static elimination unit,
An image forming apparatus comprising:


(In General Formula (1-1) and General Formula (1-2), n11, n11 ′, n12, n12 ′, n13, and n14 each independently represent an integer of 0 or more and 3 or less, provided that n11 and At least one of n12 represents an integer of 1 to 3. At least one of n11 ′ and n12 ′ represents an integer of 1 to 3. At least one of n14 and n13 represents an integer of 1 to 3. m11, m11′m12 and m12 ′ each independently represents an integer of 0 or 1. r11 represents an integer of 2 or more and 10 or less, and R ¹¹ , R ^{11 ′} , R ¹² and R ^{12 ′} each independently represent carbon number. Represents an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms.)   Voltage application for the charging member is performed such that the control unit applies the voltage applied during the completed image formation to the charging member, and applies the voltage applied during the completed image formation to the transfer member. The image forming apparatus according to claim 1, wherein the image forming unit controls a voltage application unit for the transfer unit and the transfer member.   The control unit applies a voltage to the charging member that is lower than the voltage applied during the completed image formation, and applies a voltage higher than the voltage applied during the completed image formation to the transfer member. The image forming apparatus according to claim 1, wherein the voltage applying unit for the charging member and the voltage applying unit for the transfer member are controlled.   The image forming apparatus according to claim 1, wherein the control unit further controls a voltage application unit for the developing member so as to apply a voltage to the developing member.   The predetermined relationship between the number of outputs of the same image formed continuously and the process speed of the image formation is such that the number of outputs of the same image formed continuously is equal to or greater than the predetermined number of outputs. The image forming apparatus according to claim 1, wherein a forming process speed is a relationship equal to or lower than a predetermined speed. The predetermined relationship between the number of outputs of the same image formed continuously and the process speed of the image formation is a relationship represented by the following formula (11). Image forming apparatus.
Formula (11): OP / PS ≧ 2.2
(In the formula (11), OP indicates the number of output of the same image formed continuously (sheets). PS indicates the process speed (mm / s) of image formation.) The photosensitive layer of the electrophotographic photoreceptor has a charge generation layer and a charge transport layer,
The charge transport layer comprises a charge transport material represented by the following general formula (2), a repeating unit represented by the following general formula (3), and a polycarbonate copolymer comprising a repeating unit represented by the following general formula (4) The image forming apparatus according to claim 1, comprising a united image.


(In General Formula (2), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ may be the same or different, and each represents a hydrogen atom, an alkyl group, an alkoxyl group, A halogen atom or a substituted or unsubstituted aryl group, and m1 and n2 each independently represents 0 or 1.


(In General Formula (3) and General Formula (4), R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, carbon A cycloalkyl group having 5 to 7 carbon atoms, or an aryl group having 6 to 12 carbon atoms, X represents a phenylene group, a biphenylene group, a naphthylene group, a linear or branched alkylene group, or a cycloalkylene group. .) From a conductive substrate, a binder resin, metal oxide particles, and an electron-accepting compound represented by the following general formula (1-1) and the following general formula (1-2) provided on the conductive substrate A first step of charging the surface of the electrophotographic photosensitive member having a subbing layer containing at least one selected with a photosensitive layer provided on the subbing layer with a charging member;
A second step of forming an electrostatic latent image on the surface of the charged electrophotographic photosensitive member;
A third step of developing the electrostatic latent image formed on the surface of the electrophotographic photosensitive member by a developing member with a developer containing toner to form a toner image;
A fourth step of transferring a toner image formed on the surface of the electrophotographic photosensitive member to a transfer target by a transfer member;
A fifth step of removing the charge by exposing the surface of the electrophotographic photosensitive member by a charge removing unit after transferring the toner image;
After the image formation is completed, when the output number of the same image continuously formed and the process speed of the image formation have a predetermined relationship among the completed image formation information, the voltage is applied to the charging member and the transfer member. And the sixth step of rotating the electrophotographic photosensitive member in a state where the surface of the electrophotographic photosensitive member is exposed by the static eliminator,
An image forming method comprising:


(In General Formula (1-1) and General Formula (1-2), n11, n11 ′, n12, n12 ′, n13, and n14 each independently represent an integer of 0 or more and 3 or less, provided that n11 and At least one of n12 represents an integer of 1 to 3. At least one of n11 ′ and n12 ′ represents an integer of 1 to 3. At least one of n14 and n13 represents an integer of 1 to 3. m11, m11′m12 and m12 ′ each independently represents an integer of 0 or 1. r11 represents an integer of 2 or more and 10 or less, and R ¹¹ , R ^{11 ′} , R ¹² and R ^{12 ′} each independently represent carbon number. Represents an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms.)   9. The image forming method according to claim 8, wherein in the sixth step, a voltage applied at the time of completed image formation is applied to the charging member, and a voltage applied at the time of completed image formation is applied to the transfer member. .   In the sixth step, a voltage lower than a voltage applied at the time of completed image formation is applied to the charging member, and a voltage higher than a voltage applied at the time of completed image formation is applied to the transfer member. Item 9. The image forming method according to Item 8.   The image forming method according to claim 8, wherein a voltage is further applied to the developing member in the sixth step.   The predetermined relationship between the number of outputs of the same image formed continuously and the process speed of the image formation is such that the number of outputs of the same image formed continuously is equal to or greater than the predetermined number of outputs. The image forming method according to claim 8, wherein a forming process speed is a relationship equal to or lower than a predetermined speed. The predetermined relationship between the number of outputs of the same image formed continuously and the process speed of the image formation is a relationship represented by the following formula (11). Image forming method.
Formula (11): OP / PS ≧ 2.2
(In the formula (11), OP indicates the number of output of the same image formed continuously (sheets). PS indicates the process speed (mm / s) of image formation.) The photosensitive layer of the electrophotographic photoreceptor has a charge generation layer and a charge transport layer,
The charge transport layer comprises a charge transport material represented by the following general formula (2), a repeating unit represented by the following general formula (3), and a polycarbonate copolymer comprising a repeating unit represented by the following general formula (4) The image forming method according to any one of claims 8 to 13, comprising a coalescence.


(In General Formula (2), R ¹ , R ² , R ³ , R ⁴ , R ⁵ , and R ⁶ may be the same or different, and each represents a hydrogen atom, an alkyl group, an alkoxyl group, A halogen atom or a substituted or unsubstituted aryl group, and m1 and n2 each independently represents 0 or 1.


(In General Formula (3) and General Formula (4), R ⁷ , R ⁸ , R ⁹ and R ¹⁰ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, carbon A cycloalkyl group having 5 to 7 carbon atoms, or an aryl group having 6 to 12 carbon atoms, X represents a phenylene group, a biphenylene group, a naphthylene group, a linear or branched alkylene group, or a cycloalkylene group. .) From a conductive substrate, a binder resin, metal oxide particles, and an electron-accepting compound represented by the following general formula (1-1) and the following general formula (1-2) provided on the conductive substrate An electrophotographic photoreceptor having an undercoat layer containing at least one selected, and a photosensitive layer provided on the undercoat layer,
A drive unit for rotationally driving the electrophotographic photosensitive member;
A charging member for charging the surface of the electrophotographic photosensitive member;
A voltage application unit for a charging member for applying a voltage to the charging member;
A transfer member for transferring a toner image formed on the surface of the electrophotographic photosensitive member to a transfer target;
A voltage application unit for a transfer member for applying a voltage to the transfer member;
After transferring the toner image, a charge removing unit that exposes the surface of the electrophotographic photosensitive member to remove charge;
After the image formation is completed, when the output number of the same image continuously formed and the process speed of the image formation have a predetermined relationship among the completed image formation information, the voltage is applied to the charging member and the transfer member. And the drive unit, the voltage applying unit for the charging member, and the transfer member for rotating the electrophotographic photosensitive member in a state where the surface of the electrophotographic photosensitive member is exposed by the charge eliminating unit. A voltage application unit, and a control unit for controlling the static elimination unit,
With
A process cartridge attached to and detached from the image forming apparatus.


(In General Formula (1-1) and General Formula (1-2), n11, n11 ′, n12, n12 ′, n13, and n14 each independently represent an integer of 0 or more and 3 or less, provided that n11 and At least one of n12 represents an integer of 1 to 3. At least one of n11 ′ and n12 ′ represents an integer of 1 to 3. At least one of n14 and n13 represents an integer of 1 to 3. m11, m11′m12 and m12 ′ each independently represents an integer of 0 or 1. r11 represents an integer of 2 or more and 10 or less, and R ¹¹ , R ^{11 ′} , R ¹² and R ^{12 ′} each independently represent carbon number. Represents an alkyl group having 1 to 10 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms.)