JP2003271035A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce abnormal images which occur due to discharge products generated by a discharging operation of an electrifying member, in an image forming apparatus which applies voltage to the electrifying member disposed opposite an image carrier, causes discharge between the electrifying member and the image carrier to electrify the image carrier, exposes the electrified surface to light, develops a toner image, and transfers the toner image to a recording medium. <P>SOLUTION: The rotation of the image carrier 40 is stopped after voltage supply to the electrifying member is turned off. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention applies a voltage to a charging member arranged opposite to an image carrier to charge the image carrier and forms an electrostatic latent image on the charged image carrier. The present invention relates to an image forming apparatus that makes a visible image of the electrostatic latent image and transfers the visible image directly or through an intermediate transfer member to a recording medium to obtain a recorded image.

[0002]

2. Description of the Related Art Electronic copying machines, printers, facsimiles,
Alternatively, an image forming apparatus of the above type configured as a multi-function peripheral or the like having at least these two functions has been conventionally known. In this type of conventional image forming apparatus,
When stopping the operation, the voltage application to the charging member was turned off at the same time when the image carrier was stopped. However, with this configuration, since the charge remains in the charging member even after the voltage application to the charging member is turned off, the charging operation for the image bearing member is continued for a short time even after the image bearing member is stopped. . Therefore, the image carrier is stopped in a state where a relatively large amount of electric charge is carried on the part of the image carrier facing the charging member.

In the above-mentioned state, the next image forming operation is started, and the image bearing member is charged by the charging member to which the voltage is applied. Since a relatively large amount of electric charge remains in the image carrier portion, the absolute value of the surface potential of this image carrier portion becomes higher than the absolute value of the surface potential of the other image carrier portions. As a result, the image densities of the visible images formed on the above-mentioned portions of the image carrier differ, and the overall image quality deteriorates. For example, when the image carrier is stopped, the image formed on the part of the image carrier facing the charging member becomes a blank image with reduced density.

Further, the charging member generally causes an electric discharge between the charging member and the image carrier to charge the image carrier, and the discharge product generated by the discharge is the image carrier. When it adheres to the body surface, an abnormal image called image deletion occurs. In the conventional image forming apparatus, at the same time when the voltage application to the charging member is turned off, the image carrier is stopped, and the charging member is continuously discharged for a short time even after the voltage application is turned off. Therefore, after the image bearing member stops, the discharge products floating between the image bearing member and the charging member are deposited on the surface of the image bearing member so as to be deposited, and the amount of deposition increases. Therefore, the attached discharge product may cause an abnormal image during the next image forming operation.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus which can eliminate or alleviate the above-mentioned conventional drawbacks.

[0006]

In order to achieve the above object, the present invention is an image forming apparatus of the type described at the beginning, in which the voltage application to the charging member is turned off when the image carrier is stopped. An image forming apparatus is proposed in which the image carrier is stopped later (Claim 1).

At that time, after the voltage application to the charging member is turned off, the surface of the image carrier is moved at least by the width of the discharge region in the moving direction of the surface of the image carrier, and then the image carrier is stopped. This is advantageous (claim 2).

Further, in the image forming apparatus according to claim 1 or 2, it is preferable that the charging member is positioned such that an intermediate region between respective end regions in the longitudinal direction is separated from the surface of the image carrier. Advantageous (Claim 3).

Further, in the image forming apparatus according to any one of claims 1 to 3, it is advantageous that the charging member is a charging roller that rotates in association with movement of the surface of the image carrier (claim 9). 4).

Further, in the image forming apparatus according to any one of claims 1 to 4, the voltage applied to the charging member is a DC voltage superposed with an alternating voltage.
When stopping the image carrier, it is advantageous to turn off the application of the alternating voltage to the charging member, turn off the application of the DC voltage to the charging member, and then stop the image carrier. 5).

Further, in the image forming apparatus according to any one of claims 1 to 5, the linear velocity on the surface of the image carrier can be switched in at least two stages, and the linear velocity on the surface of the image carrier can be changed. The image forming mode when V1 is the first mode, the image forming mode when the linear velocity of the image carrier surface is V2 which is higher than V1 is the second mode, and the charging is performed in the first mode. The time from turning off the application of the voltage to the member to the stop of the image carrier is T1, and the time from turning off the application of the voltage to the charging member to the stop of the image carrier in the second mode. Is T2, T1> T
It is advantageous to control the off timing of the voltage application to the charging member and the stop timing of the image carrier so that the voltage becomes 2. (Claim 6)

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic partial sectional view showing an example of an image forming apparatus. The image forming apparatus shown here has an image carrier 40, and the image carrier 40 is composed of a drum-shaped photoreceptor having a photosensitive layer on the outer peripheral surface of a cylindrical conductive base. An endless belt-shaped image carrier that is wound around a plurality of rollers and driven to rotate can also be used.

The image carrier 40 shown in FIG. 1 is rotationally driven in the direction of arrow A by a drive motor (not shown) during the image forming operation, at which time the image carrier is charged to a predetermined polarity by the charging device 1. . The image carrier 40 charged by the charging device 1 is irradiated with the light-modulated writing light L emitted from the exposure device 21 including a laser writing unit, whereby an electrostatic latent image is formed on the image carrier 40. It In the illustrated example, the absolute value of the potential of the surface portion of the image carrier irradiated with the writing light L made of laser light is reduced and becomes an electrostatic latent image (image portion). The part where the absolute value of is kept high becomes the background part. Then, when the electrostatic latent image passes through the developing device 61, it is visualized as a toner image by the toner charged to a predetermined polarity. It is also possible to use an exposure device having an LED array, an exposure device that illuminates the document surface, and forms an image of the document on the image carrier.

On the other hand, a recording medium P made of, for example, transfer paper is sent out from a paper feeding device (not shown), and the image carrier 4
Between the transfer device 62 and the image carrier 40, which are placed opposite to each other,
The recording medium P is fed at a predetermined timing as shown by an arrow B. At this time, the toner image formed on the image carrier is electrostatically transferred onto the recording medium P by the action of the transfer device 62. The recording medium P onto which the toner image has been transferred subsequently passes through a fixing device (not shown), at which time the toner image is fixed on the recording medium by the action of heat and pressure.
The recording medium P that has passed through the fixing device is discharged to a paper discharge unit (not shown). The untransferred toner left on the surface of the image carrier without being transferred to the recording medium is removed by the cleaning device 63, and then the surface of the image carrier is irradiated with light from the neutralization device 64 including a neutralization lamp. The surface of the image bearing member is subjected to static elimination action.

In the image forming apparatus shown in FIG. 1, the toner image formed on the image carrier 40 is directly recorded on the recording medium P.
However, as in an example described later, the toner image on the image carrier may be transferred to an intermediate transfer member, and then the toner image may be transferred to a recording medium. it can.

As shown in FIGS. 1 and 2, the charging device 1 has a charging member 60 arranged so as to face the surface of the image carrier. The charging member 60 can be configured in an appropriate form, but in the example shown in FIGS. 1 and 2, the charging member 60 is composed of a charging roller. The charging member 60 is a conductive base 103 formed in a columnar shape.
And a cylindrical resistance layer 104 fixed to the base 103.
And have. The resistance layer 104 is composed of one layer or a plurality of layers.

As shown in FIG. 2, each end area in the longitudinal direction of the charging member 60 is formed as a spacer section 105 having a diameter larger than that of an intermediate area therebetween, and each spacer section 105 is formed in the image carrier 40. Pressure contact with the surface of. As a result, the charging member 60 is positioned such that the intermediate region between the respective end regions in the longitudinal direction thereof is separated from the surface of the image carrier. The gap between the intermediate region and the surface of the image carrier at the closest position, that is, the minute gap G is, for example, 5 to 500 μm.
m, preferably 100 μm or less, and particularly preferably about 10 to 60 μm.

During the image forming operation, the charging member 60 composed of a charging roller is interlocked with the movement of the surface of the image carrier 40 in FIG.
Rotate in the direction indicated by the arrow. The charging member 60 may be rotated around the surface of the image carrier, or the charging member 60 may be rotationally driven by a driving device (not shown). At this time, the conductive substrate 103 of the charging member 60 is electrically connected to a power source (not shown), and a predetermined charging voltage is applied to the charging member 60. As a result, electric discharge is generated in the gap between the charging member 60 and the surface of the image carrier, and the image carrier 40 is charged to a predetermined polarity.

As described above, in the image forming apparatus of this embodiment, a voltage is applied to the charging member arranged to face the image carrier to charge the image carrier, and the electrostatic latent image is applied to the charged image carrier. An image is formed, the electrostatic latent image is visualized, and the visible image is transferred to a recording medium directly or via an intermediate transfer member to obtain a recorded image.

Here, when the operation of the image forming apparatus is stopped, the rotation of the image carrier 40 is stopped and the application of the voltage to the charging member 60 is turned off. Conventionally, the image carrier is stopped. Since the application of the voltage to the charging member was turned off at the same timing, the above-mentioned drawbacks were unavoidable.

Therefore, in the image forming apparatus of this example,
When the image carrier 40 is stopped, the voltage application to the charging member 60 is turned off, and then the image carrier 40 is stopped. According to this configuration, even after the voltage application to the image carrier 60 is turned off, the charge remaining on the charging member 60 causes the discharge to continue and the charging operation for the image carrier 40 is performed. Even after the application of the voltage is turned off, the surface of the image carrier 40 continues to move in the direction of the arrow A. There is no stopping.
The image carrier 40 does not stop in the state where a part of the charged potential in the circumferential direction of the image carrier 40 becomes high. Therefore, the next image forming operation is started, the image carrier 40 starts to rotate in the direction of arrow A, and when the voltage is applied to the charging member 60 to charge the image carrier 40, the charging member 60 is stopped when stopped. The absolute value of the charging potential of the image carrier portion that has been opposed to is not abnormally higher than that of the other image carrier portions. As a result, at the time of the next image forming operation, part of the image density does not significantly differ from the image density of the other part, and the overall image quality can be improved.

Further, due to the rotation of the image carrier 40, an air flow flowing in the same direction as the rotating direction of the image carrier is generated around the surface of the image carrier 40. Therefore, when the image carrier is stopped after the voltage application to the charging member 60 is turned off, the charging member 60 and the image carrier 40 are stopped when the voltage application is turned off.
Between the image carrier and the discharge product existing between the image carrier and the discharge product generated by the discharge performed for a short time after the voltage application is turned off. It moves from the region between 40 and the charging member 60 to the downstream side in the image carrier surface movement direction. Therefore, when the image carrier 40 stops, a large amount of discharge products do not float in the region between the image carrier 40 and the charging member 60. Therefore, when the image carrier 40 is stopped, the charging member 60 is
It is possible to prevent a large amount of discharge products from adhering to the surface portion of the image bearing member facing to and to prevent the occurrence of an abnormal image due to the discharge products during the next image formation.

In FIG. 3, the image carrier 40 rotates in the direction of arrow A, and the charging member 60 rotates in the direction of arrow.
FIG. 6 is an explanatory diagram schematically showing a discharge area X when the image carrier 40 is being charged, and in this figure, the discharge area X is shown by hatching. Reference numeral W1 in FIG. 3 indicates the width of the discharge region in the moving direction A of the surface of the image carrier.

As described above, the image carrier 40 is stopped after the voltage application to the charging member 60 is turned off. At that time, from the time when the voltage application to the charging member 60 is turned off, It is desirable to stop the image carrier 40 after moving the surface of the image carrier by at least the discharge region width W1 in the moving direction A of the image carrier surface. According to this structure, as schematically shown in FIG. 3, when the voltage application to the charging member 60 is turned off, the discharge products existing in the most upstream side of the discharge region X in the image carrier surface moving direction. Before the image carrier 40 is stopped, PA rides on the air flow F1 accompanying the rotation of the image carrier 40 and flows out from the area between the image carrier 40 and the charging member 60. As a result, after the image carrier 40 stops, the image carrier 40 and the charging member 6
It is possible to particularly reduce the amount of discharge products existing during 0, and it is possible to more effectively prevent the occurrence of an abnormal image during the next image forming operation.

The time required for the image carrier 40 to move by the width W1 of the discharge area after the voltage application to the charging member 60 is turned off is the value obtained by dividing the discharge area width W1 by the linear velocity of the surface of the image carrier. Therefore, the image carrier 40 may be stopped when this time or more has elapsed since the voltage application to the charging member 60 was turned off. The time from when the voltage application to the charging member 60 is turned off to when the image carrier 40 stops is T
Then, the time T can be determined as follows, for example. That is, the discharge area width W1 is 1.4 m
m, when the linear velocity V on the surface of the image carrier is 282 mm / s,
W1 / V = 1.4 / 282 = 4.96 ms. At that time, when it is assumed that the time required for the high voltage power supply to the charging member 60 to fall is 100 ms, the total time of this time and the above time (100 ms + 4.96 ms) or more, for example, 110
The time T is set to ms.

As described above, in the charging member 60 of this example, the intermediate region between the end regions in the longitudinal direction is located apart from the surface of the image carrier, and the charging member 60 is
Since the charging roller is configured to rotate in association with the movement of the surface of the image carrier, the air flow F1 is reliably formed between the image carrier 40 and the charging member 60. Therefore, the above-described effects can be more reliably exhibited, but the present invention is applicable to the case where the charging member is a corona discharger having a charge wire, a charging blade, a charging brush, or the like, or the intermediate region of the charging roller. It can also be applied when it is in contact with the surface of the image carrier.

The charging voltage applied to the charging member 60 may be only a DC voltage, but it is preferable to apply a voltage obtained by superimposing an alternating voltage on the DC voltage to the charging member 60. If the electric resistance in the current path formed by the resistance layer 104 of the charging member 60 is non-uniform, applying only a DC voltage to the charging member may result in non-uniform charging potential of the image carrier. When a charging voltage obtained by superimposing an alternating voltage on a DC voltage is applied to the charging member 60, the potential of the charging member surface becomes the same, the discharge is stabilized, and the effect of uniformly charging the surface of the image carrier is enhanced.

In FIG. 4, when the image carrier is stopped, the DC voltage and the alternating voltage applied to the charging member 60 are simultaneously turned off, and after a lapse of T time from that point, the drive motor for the image carrier 40 is turned off. An example is shown in which the image carrier is stopped.

On the other hand, in FIG. 5, when the image carrier 40 is stopped, the application of the alternating voltage to the charging member 60 is turned off, and then the application of the DC voltage to the charging member 60 is turned off.
Then, after T time, the drive motor is turned off to turn off the image carrier 40.
The example which stops is shown.

The linear velocity on the surface of the image carrier is at least 2
In order to obtain an image with a high image density, the linear velocity on the surface of the image carrier is lowered to improve the image quality, and conversely, when the image forming speed is increased, the image carrier is It can also be configured to increase the surface linear velocity. At that time, the image forming mode when the linear velocity of the image carrier surface is V1 is the first mode, and the image forming mode when the linear velocity of the image carrier surface is V2 which is higher than V1 is the second mode. And the charging member 6 in the first mode.
The time from turning off the voltage application to 0 to stopping the image carrier 40 is T1, and the charging member 60 is in the second mode.
When the time from turning off the application of the voltage to the image carrier to the stop of the image carrier is T2, the off timing of the voltage application to the charging member and the stop timing of the image carrier are controlled so that T1> T2. It is desirable to do. Thus, in any mode, the time from the time when the voltage application to the charging member 60 is turned off to the time when the image carrier is stopped can be set to a value that does not cause the conventional defects.

For example, the linear velocity V2 on the surface of the image carrier in the second mode is 282 mm / s, and the linear velocity V1 on the surface of the image carrier in the first mode is half that in the second mode, that is, 2
When 82/2 mm / s = 141 mm / s, the discharge area width W1
Is 1.4 mm, W1 / V in the first mode
1 = 9.92 ms. Therefore, also in this case, the time T1 from the time when the voltage application to the charging member 60 is turned off to the time when the image carrier is stopped is larger than the value obtained by adding the high voltage power supply falling time 100 ms to the above value 9.92 ms, for example. It can be controlled to be 115 ms.

At the start of the image forming operation, as shown in FIGS. 4 and 5, the application of the DC voltage to the charging member 60 and the application of the alternating voltage may be simultaneously performed, or the alternating operation with respect to the charging member 60 may be performed. The application of the DC voltage may be started prior to the application of the voltage. In either case,
Before the start of voltage application to the charging member 60, the image carrier 40
It is preferable to start the rotation.

Although the example of the image forming apparatus for forming a monochromatic image has been described above, the above-described configurations can be widely applied to other types of image forming apparatuses. An example of another type of image forming apparatus to which each of the above configurations can be applied will be described below.

FIG. 6 is a schematic view showing an image forming apparatus using an electrophotographic system. The image forming apparatus shown here is a sheet feeding table 200 and an image forming section 100 supported by the sheet feeding table 200.
And a scanner 300 mounted thereon, and an automatic document feeder 400 further mounted thereon. The image forming apparatus shown in FIG. 6 is configured as an electronic copying machine.

The scanner 300 includes a contact glass 32 on which a document (not shown) is placed, and a first traveling body 33 which is arranged below the contact glass 32 and has a light source and a first mirror.
A second traveling body 34 having second and third mirrors, an image forming lens 35, and a reading sensor 36 composed of, for example, a CCD.

When making a copy using the image forming apparatus shown in FIG. 6, a document is set on the document table 30 of the automatic document feeder 400, or the automatic document feeder 400 is opened and the contact of the scanner 300 is made. A document is set on the glass 32, then the document automatic feeding device 400 is closed, and the device 400 presses the document on the contact glass 32.

When a start switch (not shown) is pressed, when the original is set on the automatic document feeder 400, the original is conveyed onto the contact glass 32 or the original is placed on the contact glass 32. When set, the scanner 300 immediately starts to operate and the first and second traveling bodies 33 and 34 move from their home positions to the right in FIG. At this time, the light emitted from the light source of the first traveling body 33 illuminates the original document placed on the contact glass 32, and the reflected light reflects the first mirror of the first traveling body 33 and the first traveling body of the second traveling body. The light is reflected by the second and third mirrors and passes through the imaging lens 35,
A document image is formed on the reading sensor 36, and the content of the document image is read.

On the other hand, in the image forming unit 100, a recorded image corresponding to the image information read as described above is formed as follows.

The image forming unit 100 shown in FIG. 6 has first to fourth image forming means 18BK, 18Y, 18M and 18C arranged in its main body housing, as shown in an enlarged view in FIG. Then, the image carriers 40BK, 40Y, 40 of the respective image forming means.
A black toner image, a yellow toner image, a magenta toner image, and a cyan toner image are respectively formed on M and 40C, and the toner images of the respective colors are transferred to the intermediate transfer member 10. The intermediate transfer member 10 is composed of an endless belt wound around first to third supporting rollers 14, 15 and 16, and the first supporting roller 14 and the second supporting roller 14 are connected to each other.
First to fourth image forming units 18BK, 18Y, 18M, and 18C are arranged side by side in the horizontal direction on the intermediate transfer member portion stretched between the supporting rollers 15 of the above. ing. Such an image forming apparatus is called a tandem type image forming apparatus. Multiple image carriers 40
When it is necessary to identify BK, 40Y, 40M, and 40C, these are respectively referred to as a first image carrier 40BK, a second image carrier 40Y, a third image carrier 40M, and a fourth image carrier. 40C.

The image bearing members 40BK to 40 shown in FIG.
Although C is configured as a drum-shaped photoconductor that is rotationally driven in the direction of arrow A, as described above, the endless belt-shaped photoconductor that is rotationally driven by being wound around a plurality of support rollers is used. It is also possible to use the image carrier. Similarly, the intermediate transfer member 10 shown in FIGS. 6 and 7 has a plurality of first transfer members.
Through an endless belt wound around the third supporting rollers 14, 15 and 16 and driven to rotate in the direction of arrow B,
It is also possible to use a drum-shaped intermediate transfer member that is rotationally driven.

First to fourth image carriers 40BK, 40
Since the toner image of each color is formed on M, 40Y, and 40C, and the operation of transferring the toner image to the intermediate transfer body 10 is substantially the same, the operation is mainly performed on the first image carrier 40BK. A toner image is formed on the intermediate transfer member 1
Only the configuration and the operation of transferring onto 0 will be described.

FIG. 8 is an enlarged view of the first image carrier 40BK and the image forming elements arranged around it. During the image forming operation, the image carrier 40BK is driven to rotate in the direction of arrow A. At this time, the image carrier 40BK is uniformly charged by the charging device 1BK to a predetermined polarity, in the illustrated example, a negative polarity. As shown in FIG. 6, an exposure device 21 is arranged above the image carrier 40BK, and the writing light modulated from the exposure device 21 in accordance with the image information read by the scanner 300 as described above. L (FIG. 8) is emitted, and the writing light L is applied to the charged surface of the image carrier to form an electrostatic latent image on the image carrier 40BK. The exposure device 21 is, for example, a laser or an LED.
It is configured as a device for emitting the writing light. Also in this example, the portion of the image carrier on which the absolute value of the surface potential has been lowered by being irradiated with the writing light L is the electrostatic latent image (image portion).
Therefore, the image carrier portion where the absolute value of the potential is kept high without being irradiated with the writing light L becomes the background portion.

The electrostatic latent image is the developing device 61BK.
When it passes through, it is visualized as a black toner image.
The image carrier 40BK of this example is, as shown in FIGS. 9 and 11, a conductive support 101BK formed in a drum shape.
And a photosensitive layer 102BK fixedly supported on the outer peripheral surface thereof. The photosensitive layer 102BK is charged and exposed as described above to form an electrostatic latent image on the photosensitive layer 102BK, and the electrostatic latent image is formed. Is visualized as a toner image. As described above, an image carrier made of an endless belt-shaped photoconductor can be used, but in this case, the photosensitive layer is supported on a conductive support made of an endless belt. The image carrier can be configured in various forms, a specific example of which will be described later.

One of the first to third supporting rollers 14, 15, 16 for the intermediate transfer member 10 shown in FIGS. 6 and 7 is configured as a driving roller, and the driving roller is driven by a driving motor (not shown). It is driven to rotate. As a result, the intermediate transfer member 10 is rotationally driven in the direction of arrow B, and the other two support rollers are driven to rotate. For example, as shown in an enlarged view in FIG. 16, the intermediate transfer member 10 is composed of a base layer 11, an elastic layer 12 provided thereon, and a surface layer 13 provided on the surface thereof, and the surface layer is an intermediate layer. It is located on the front surface side of the transfer body 10, and the base layer 11 is located on the back surface side.

Image carrier 4 with the intermediate transfer member 10 interposed therebetween.
As shown in FIG. 8, a primary transfer device 62BK is arranged at a position substantially opposite to 0BK. In the illustrated example, the primary transfer device 62BK is composed of a transfer roller which is rotationally driven in the arrow direction while being in pressure contact with the back surface of the intermediate transfer member 10. A transfer voltage having a polarity opposite to that of the toner of the toner image on the image carrier 40BK, that is, a positive polarity in the illustrated example, is applied to the primary transfer device 62BK.
The monochromatic black toner image formed on the first image carrier 40BK is on the surface of the intermediate transfer body 10 which contacts the image carrier 40BK and moves in the direction of arrow B in synchronization with the image carrier 40BK. Transcribed. Instead of the transfer roller, a primary transfer device including, for example, a conductive transfer brush, a transfer blade, or a corona charger arranged apart from the back surface of the intermediate transfer body 10 may be used.

The transfer residual toner adhering to the surface of the image carrier 40BK which has passed through the transfer position where the toner image is transferred as described above is the cleaning device 63 for the image carrier.
It is removed by BK and the surface of the image carrier 40BK is cleaned. Then, the surface of the image bearing member is subjected to the charge removing action by the charge removing device 64BK, the surface potential thereof is initialized, and the image carrier is prepared for the image formation again. The static eliminator 64BK is composed of, for example, a static eliminator, and irradiates the surface of the image carrier with light from the static eliminator to initialize the surface potential of the image carrier 40BK.

As shown in FIG. 7, with respect to the moving direction of the intermediate transfer member 10, the second to fourth image bearing members 40Y, 40M, 40 arranged downstream of the first image bearing member 40BK.
A yellow toner image, a magenta toner image, and a cyan toner image are respectively formed on C in the same manner as described above, and the monochromatic toner images are formed by the operations of the primary transfer devices 62Y, 62M, and 62C. , And the black toner image is sequentially transferred onto the intermediate transfer member 10. In this way, a four-color composite color image is formed on the intermediate transfer member.

In each figure, the image forming elements of the second, third and fourth image forming means 18Y, 18M and 18C are attached to the corresponding image forming elements of the first image forming means 18BK. Instead of the symbol BK, a symbol with Y, M, and C respectively added. The second to fourth image forming means 18Y, 18M,
The basic configuration and operation of 18C are the same as those of the developing devices 61Y and 61Y.
The image carrier 40Y, 40M, 40
There is no difference except that a yellow toner image, a magenta toner image, and a cyan toner image are formed on C, respectively.
Therefore, although the description thereof is omitted, a more specific configuration example of each component of the image forming unit will be clarified later.

Elements designated by reference numeral 74 in FIG. 7 are primary transfer devices 62BK, 62Y, 62M and 62C.
Is a conductive roller that comes into contact with the back surface of the intermediate transfer body 10, that is, the side of the base layer. These conductive rollers 74, when transferring a toner image from each image carrier to the intermediate transfer body 10, Each primary transfer device 62BK, 62Y,
It serves to prevent the electric currents respectively supplied to 62M and 62C from flowing into the adjacent image forming means through the medium resistance base layer of the intermediate transfer member 10.

On the other hand, a secondary transfer device 22 is provided on the side opposite to each image carrier with the intermediate transfer member 10 interposed therebetween. The secondary transfer device 22 illustrated here includes two rollers 23,
It has an endless secondary transfer belt 24 which is hung around 23 and driven to rotate in the direction of arrow C.
Are pressed against the third supporting roller 16 via the intermediate transfer member 10.

As shown in FIG. 6, in the paper feed table 200, a plurality of paper feed cassettes 44 and a recording medium (not shown) composed of transfer paper or resin sheets housed in each of the paper feed cassettes 44 is shown. ) Is provided, and a paper feeding device 43 having a paper feeding roller 42 is provided. Any one of the selected paper feed cassettes 4 when the start switch is pressed
The paper feed roller 42 corresponding to No. 4 rotates, and the recording medium loaded in the paper feed cassette 44 is sent out. The fed recording mediums are separated one by one by a separation roller 45, enter a paper feed path 46, and then are conveyed by a conveyance roller 47 while being guided to a paper feed path 48 of the image forming unit 100 and a pair of registration rollers. It is hit by 49 and stopped.

Alternatively, a recording medium is set on the manual feed tray 51, the recording medium is fed by the rotation of the paper feed roller 50, the recording medium is separated by the separating roller 52 one by one, and one separated recording is made. The medium may be guided to the manual paper feed path 53, and may be abutted against the registration roller 49 and stopped.

In any case, the registration roller 49 starts rotating at the timing when the composite color image transferred on the intermediate transfer member 10 is aligned with the recording medium. As a result, the recording medium is conveyed between the intermediate transfer body 10 and the secondary transfer belt 24, and the operation of the secondary transfer device 22 causes the recording medium to be transferred.
The composite color image on 0 is secondarily transferred to the recording medium. The transfer residual toner that has not been transferred to the recording medium and is attached on the intermediate transfer body 10 is a cleaning device 17 for the intermediate transfer body, which is arranged so as to face the second support roller 15 with the intermediate transfer body 10 interposed therebetween. And the surface of the intermediate transfer body 10 is cleaned. In this way, the intermediate transfer member 1
It is possible to repeatedly transfer a composite color image onto the image display.

The recording medium to which the composite color image has been transferred is
Subsequently, the secondary transfer belt 24 is carried and conveyed, and then passes through the fixing device 25 shown in FIG. 6, at which time the combined color image is fixed on the recording medium by the action of heat and pressure. The recording medium that has passed through the fixing device 25 is discharged onto a paper discharge tray 57 by a discharge roller 56. As described above, the secondary transfer belt 24 also has a sheet conveying function of conveying the recording medium after the image transfer to the fixing device 25. The fixing device 25 shown in FIG. 6 has an endless fixing belt 26 and a pressure roller 27 pressed against the fixing belt 26.
When the recording medium is conveyed between the fixing belt 26 and the pressure roller 27, the composite color image is fixed on the recording medium. Instead of the secondary transfer device having the secondary transfer belt 24, it is also possible to use a secondary transfer device including a transfer roller or a corona charger arranged apart from the intermediate transfer member.

Further, in the image forming apparatus shown in FIG. 6, a sheet reversing device 28 for reversing the recording medium to form images on both sides of the recording medium is provided below the secondary transfer device 22 and the fixing device 25. ing. When images are formed on both sides of the recording medium, the recording medium that has passed through the fixing device 25 as described above is sent to the sheet reversing device 28 by switching the switching claw 55, and the front and back of the recording medium are reversed here. And again feeds it between the intermediate transfer body 10 and the secondary transfer device 22, and also the intermediate transfer body 10 on the back surface of the recording medium.
Transfer the composite color image above and fix the image in the fixing device 25.
After being fixed by, the recording medium is discharged onto the discharge tray 57 by the discharge roller 56.

Next, the specific structure of the charging devices 1BK, 1Y, 1M and 1C provided in each of the image forming means 18BK to 18C will be described here.
K will be described as an example. As shown in FIGS. 8, 9 and 17, the charging device 1BK has a charging member 60BK arranged on the surface of the image carrier 40BK so as to face it. Also in this example, the charging member is composed of a cylindrical charging roller. The charging member 60BK includes a cylindrical conductive base 103BK and a resistance layer 104BK that covers the outer peripheral surface of the base 103BK and is fixed to the base 103BK. The image carrier 40 is formed in each end region in the longitudinal direction of the resistance layer 104BK.
Spacer portions 105BK that contact the BKs are provided, respectively.

The end regions of the resistance layer are the ends of the resistance layer in the longitudinal direction, or the positions closer to the central portion CBK of the resistance layer in the longitudinal direction than the ends. In the example shown,
Each spacer portion 10 is provided at each end portion in the longitudinal direction of the resistance layer 104BK.
5BK is provided, but each spacer portion 105B is located at a position, for example, a few mm closer to the central portion CBK than each end portion thereof.
K may be provided. Further, in the illustrated example, two spacer parts 105BK are provided, but three or more spacer parts may be provided, and at least two spacer parts are provided.

The outer peripheral surface of each spacer portion 105BK is annular, and its outer diameter is larger than the outer diameter of the annular outer peripheral surface of the other resistance layer portion. When the spacer portion 105BK abuts on the image carrier 40BK, the resistance layer portion between the spacer portions 105BK is positioned to face the surface of the image carrier 40BK with a minute gap G therebetween. This minute gap G, that is, the spacer portion 1
The gap between the resistance layer portion between 05BK and the image carrier 40BK at the closest position is set to, for example, 5 to 500 μm, preferably 100 μm or less, as in the example shown in FIG.

The substrate 103BK is made of a high-rigidity material having a volume resistivity of, for example, 10 ³ Ω · cm or less, preferably 10 ² Ω · cm or less. For example, the diameter is 8 ~
The base 103 is made of a metal material such as stainless steel or aluminum having a thickness of about 20 mm, or a highly rigid conductive resin.
BK is constructed. In this example, the base body 103BK constitutes the core shaft of the charging roller.

Each end portion in the longitudinal direction of the base body 103BK as described above is rotatably supported by the support through bearings 106BK (only one of which is shown in FIG. 17). In the illustrated example, a cartridge case 8 described later as shown in FIG.
The support is constituted by a part of 9BK. Each of the bearings 106BK is pressed by a pressing means (not shown) composed of, for example, a compression spring, and thereby the charging member 60B.
Each K spacer portion 105BK is brought into pressure contact with the image carrier 40BK.

When the image bearing member 40BK rotates during the image forming operation, the charging member 60BK has both spacer portions 10a and 10b.
5BK rotates in the clockwise direction in FIG. 8 while being in pressure contact with the image carrier 40BK. At that time, the charging member 60BK may be rotated together with the rotation of the image bearing member 40BK by the frictional force acting between the image bearing member 40BK and the charging member 60BK, but in this example, as shown in FIG. The gear 108BK provided on the image carrier 40BK, and the charging member 60.
The gear 109BK fixed to the base 103BK of the BK (see FIG.
(Only shown in FIG. 7), and the charging member 60BK is rotationally driven by being driven by the rotation of the image carrier 40BK. It is also possible to dispose the charging member 60BK so as to face the image carrier 40BK without rotating the charging member 60BK.

The base 103BK of the charging member 60BK is electrically connected to a power source (not shown), and a voltage is supplied from the power source to the base 103BK during the image forming operation. As a result, discharge is generated in the gap between the charging member 60BK and the image carrier 40BK, and the image carrier 40BK, more precisely, the photosensitive layer 102BK thereof, is charged to a predetermined potential. In this way, the voltage is applied to the charging member 60BK to charge the image carrier 40BK. The voltage applied to the charging member 60BK may be a direct current voltage or a voltage obtained by superimposing an alternating voltage on the direct current voltage.

In the illustrated example, the charging member 60BK
Of the resistance adjusting layer 110BK is an annular resistance adjusting layer 110BK fixed to the surface of the base 103BK, and the resistance adjusting layer 1
Surface layer 11 fixed on the surface of 10BK over the entire circumference
1 BK, but the resistance layer can be configured in any other suitable form. For example, the surface layer may be omitted, and the resistance layer may be composed of only the resistance adjustment layer, or the resistance layer may be composed of a large number of layers of three or more layers.

The volume resistivity of the resistance adjusting layer 110BK is set to, for example, about 10 ^{5 to} 10 ⁹ Ω · cm, and the thickness thereof is preferably set to, for example, about 1 to 2 mm.
The volume resistivity of the surface layer 111BK is, for example, 10 ^{6 to} 10
It is preferable that the volume resistivity of the surface layer is set to about ¹⁰ Ω · cm, and the volume resistivity of the surface layer is slightly higher than that of the resistance adjusting layer 110BK. The surface layer 111BK preferably has a thickness of 1 to 20 μm, for example. Resistance adjustment layer 11
When the volume resistivity of 0BK is higher than 10 ⁹ Ω · cm,
There is a risk that the discharge will be insufficient and the surface of the image bearing member will not be sufficiently charged.
0 Below the ^{5 Ω} · cm, the photosensitive layer of the image carrier 40BK 1
If the 02BK has a defect such as a pinhole, the discharge current is concentrated in the pinhole to cause abnormal discharge, and the overcurrent may further expand the pinhole to destroy the photosensitive layer. The surface layer 111BK prevents the surface of the charging member 60BK from being contaminated by toner or the like, and thus the surface layer 111BK is made of a material having a high releasability. Resistance adjusting layer 110BK and surface layer 11
The specific material name of 1BK will be described later.

Here, in the charging device 1BK of the present example, as shown in FIGS. 9 and 10, each end region in the longitudinal direction of the resistance layer 104BK protrudes outward in the radial direction from the resistance layer portion between them. And its protruding part
The spacer portion 105BK described above is configured. In the example shown here, the thickness of the resistance adjustment layer 110BK in each end region of the resistance layer 104BK is thicker than the thickness of the resistance adjustment layer portion in between, but the surface layer in each end region of the resistance layer 104BK. 111 BK thickness or surface layer 11
It is also possible to make the spacer portion 105BK by making the thicknesses of the 1BK and the resistance adjustment layer 110BK thicker than the thicknesses of other portions. The spacer portion can be similarly formed on the resistance layer having no surface layer.

As described above, the spacer portions 105BK are formed by making the thickness of each end region in the longitudinal direction of the resistance layer 104BK thicker than the thickness of the resistance layer portion between them.
Since the spacer portion 105BK is composed of a part of the resistance layer 104BK, the spacer portion is locally formed like a conventionally used spacer portion formed of a gap tape joined to the surface of the resistance layer 104BK. The risk of peeling off and damage can be eliminated. Accordingly, the minute gap G between the resistance layer portion between the spacer portions 105BK and the surface of the image bearing member 40BK can be kept constant for a long period of time, and the image formed on the image bearing member 40BK can be formed. Quality can be improved over a long period of time. The life of the charging member 60BK can be extended.

As a method of manufacturing the charging member 60BK by forming the resistance adjusting layer 110BK and the surface layer 111BK on the substrate 103BK, a method of molding the resistance adjusting layer 110BK and the surface layer 111BK around the substrate 103BK using a mold, Examples thereof include a method of forming the resistance adjustment layer 110BK and the surface layer 111BK by spray coating or another general coating method.

FIG. 11 shows another example of the charging device 1BK.
The basic structure of the charging device 1BK illustrated here is the same as that of the charging device shown in FIGS.
It has a charging member 60BK arranged opposite to the surface of BK,
The charging member 60BK includes a base 103BK and the base 1
It has a resistance layer 104BK fixed to 03BK, and a voltage from a power source is supplied to the conductive base 103BK. In this way, the voltage is applied to the charging member 60BK to charge the image carrier 40BK.

The difference from the charging device shown in FIGS. 9 and 10 is that the adhesive 11 is applied to each end region of the resistance layer 104BK.
Gap holding member 113BK joined via 2BK
This is the point that the spacer portion 105BK is constituted by. Both the gap holding members 113BK are the image carrier 40BK.
And the resistance layer portion between both gap holding members 113BK is located facing the surface of the image carrier with a small gap G, and a discharge is generated in the gap between the charging member 60BK and the image carrier 40BK. As a result, the image carrier 40BK, more precisely, the photosensitive layer 102BK thereof, is charged to a predetermined potential. In the illustrated example, the gap holding member 113BK
Is composed of a gap tape, and a layered adhesive 112BK is preliminarily laminated on the gap tape to form an adhesive tape, and the adhesive tape is adhered over the entire circumference of each end region of the resistance layer 104BK. This structure itself is no different from the conventional charging member.

Here, as can be seen from FIG. 11 and FIG. 12, in the radial direction of the charging member 60BK, the resistance layer portion to which the gap holding member 113BK is joined is more radial than the resistance layer portion between the gap holding members 113BK. Recessed recess 11
4BK is formed, and the adhesive 112 is placed in the recess 114BK.
It is arranged in a state where BK is embedded. Other configurations of the charging device 1BK shown in FIGS. 11 and 12 are the same as the configurations of the charging device described above with reference to FIGS. 6 to 10.

Since the gap holding member bonded to the surface of the resistance layer via the pressure sensitive adhesive comes into pressure contact with the image carrier, a large pressing force is applied to the pressure sensitive adhesive. For this reason, as shown by the chain line arrow E in FIG. 12, the adhesive is squeezed out, and the toner on the image bearing member which cannot be completely removed by the cleaning device adheres little by little to the squeezed out adhesive, which grows. As a result of the fine gap being restricted by such toner, the fine gap may become excessively large.

However, in the charging member 60BK shown in FIGS. 11 and 12, the adhesive 11 is placed in the recess 114BK.
Since 2BK is located, even if a large pressing force is applied to the adhesive 112BK, it does not protrude in the direction of the chain line arrow E, and even if it protrudes, it is kept in a very small amount. Therefore, the minute gap G can be prevented from becoming excessively large, and the minute gap G can be maintained for a long period of time.
It is possible to prevent the charging failure of the image carrier and the accompanying deterioration of the image quality from occurring.

If the resistance adjusting layer 110BK is made of a hard material, for example, a hard resin, the roundness of the charging member can be easily obtained, fluctuation of the outer diameter of the charging member due to environmental changes can be suppressed, and a minute gap can be formed. Although it is possible to enhance the effect of keeping it constant, if the charging member is configured in this way, the pressure-sensitive adhesive will receive pressure from the hard resistance adjusting layer and the surface of the image carrier that is also hard, so the pressure-sensitive adhesive will stick out. It will be easier. On the other hand, in the case of the charging member 60BK shown in FIGS. 11 and 12, the resistance adjusting layer 11
Even when 0BK is made of a hard material, the sticking out of the adhesive can be effectively suppressed.

As shown by the arrow F in FIG. 12, the adhesive 112BK is the central portion C of the charging member 60BK in the longitudinal direction.
Even if it slightly protrudes to the side opposite to BK (FIG. 11), the adhesive does not adhere to the surface of the resistance layer between the spacer portions 105BK, so that the minute gap G does not become large.

Further, as shown in FIG. 13, the resistance layer 104
When a concave portion 114BK formed of an annular groove is formed in each end area of the BK, the adhesive 112BK is embedded therein, and the adhesive 112BK is arranged so as to be sealed in the groove, the protrusion of the adhesive 112BK is further improved. It can be prevented more effectively.

Further, in the example shown in FIGS. 11 to 13, the surface layer 111 in each end region of the resistance layer 104BK is used.
BK is cut off and the resistance adjusting layer 110B in the end region is cut off.
The recess 114BK was formed in a state where a part of the surface K was removed, but when the thickness of the surface layer 111BK was large, the surface layer 1
It is also possible to form the recess 114BK by cutting each end region of 11BK only. Further, as shown in FIGS. 14 and 15, it is also possible to form a concave portion 114BK while leaving the surface layer 111BK, and dispose the adhesive 112BK on the concave portion 114BK to bond the gap holding member 113BK to the resistance layer 104BK.

The recess 114BK shown in FIGS. 11 to 15.
The configuration of is a charging member 60BK provided with a resistance layer having no surface layer.
It is clear that it can also be applied to. Further, other configurations of the charging device shown in FIGS. 13 to 15 are the same as those of the charging device shown in FIG. 11.

By the way, the charging device 1 of each example described above
In BK, as can be seen from FIGS. 9 and 11, the spacer portion 105BK of the charging member 60BK is the image carrier 4.
It is in contact with the photosensitive layer 102BK of 0BK. that time,
It is preferable that each spacer portion 105BK abuts on the photosensitive layer portion outside the image forming area W where the image of the photosensitive layer 102BK is formed. In this way, since the spacer portion 105BK does not contact the image forming area W, the image forming area W can be uniformly charged, and a high quality image can be formed.

Alternatively, the photosensitive layer 102 of the image carrier 40BK
It is also possible to make the spacer portion 105BK abut on the surface of the support body 101BK outside the BK.

Further, each charging member 60BK described above
The spacer portion 105BK is
It protrudes radially outward of the charging member by δ from the resistance layer portion between BK, but the protrusion amount is 5 to 500 μm.
By forming the spacer portion 105BK so as to satisfy the above condition, the minute gap G can be set to 5 to 500 μm as described above. If the minute gap G is narrower than this range, the surface portion of the resistance layer between the spacer portions 105BK may come into contact with the image carrier 40BK to cause stains on the surface portion. Poor charging of the carrier 40BK may occur.

In the illustrated charging member 60BK, the resistance layer 104BK has a resistance adjustment layer 110BK fixed to the base 103BK and a surface layer 111BK fixed to the resistance adjustment layer 110BK. The base material of the resistance adjustment layer 110BK is urethane, SBR,
EVA, SBS, SEVS, SIS, TPO, EPD
Examples thereof include resins and rubbers such as M, EPM, NBR, IR, BR, silicone rubber, and epichlorohydrin rubber. The rubber or resin of these base materials may or may not have resistance to itself. It is necessary that the charging member can be uniformly charged in the longitudinal direction and the circumferential direction when a constant current flows. Therefore, a rubber or resin as a base material is mixed with a resistance adjusting agent so as to have uniform resistance in both the longitudinal and circumferential directions. As the resistance adjusting agent, a carbon black, carbon fiber, a metal oxide, a metal powder, a solid electrolyte such as perchlorate, or a conductivity-imparting agent such as a surfactant is used.

At this time, if the base material of the resistance adjusting layer 110BK is made of rubber or resin having JIS A hardness of 80 degrees or more, the straightness of the charging member 60BK can be maintained with high accuracy, and the minute gap G can be further reduced. It is possible to reliably keep it constant. In addition, rubber or resin has good workability, the charging member can be easily manufactured, and the resistance adjusting layer 110BK can have an appropriate resistance.

The resistance adjusting layer 110BK preferably contains a base material and a resistance adjusting agent in an amount of 30 to 90% by weight. If the amount of resistance modifier is less than this,
The resistance of the resistance adjusting layer 110BK becomes the resistance of the base material itself, so that an appropriate resistance of the resistance adjusting layer cannot be obtained, and it becomes difficult to uniformly disperse the resistance adjusting agent in the base material. On the other hand, when the amount of the resistance adjusting agent is larger than the above range, the resistance of the resistance adjusting layer is too low and it becomes difficult to make the resistance uniform. Further, depending on the property of the resistance adjusting agent, when a resistance adjusting agent which is difficult to disperse is used, if the amount thereof is too large, there arises a problem that the dispersion becomes particularly difficult.

Further, the surface layer 111B of the resistance layer 104BK.
K is for preventing the toner from adhering to the charging member when the toner that has passed through the cleaning device 63BK enters the charging member 60BK without being completely removed by the cleaning device 63BK, thereby lowering the charging efficiency. Therefore, the surface layer 111BK is required to have high releasability from toner. The surface layer 111BK can also be made of a material in which a resistance adjusting agent is dispersed in a base material, and as the base material, materials such as rubber and resin exemplified above, particularly fluororesin, silicone resin, acrylic resin,
An appropriate material such as polyamide resin, polyester resin, polyvinyl butyral resin, polyurethane resin or the like can be used. As the resistance adjusting agent for the surface layer 111BK, for example, an electron conductive conductive agent made of carbon black such as Ketjen black or acetylene black, a metal oxide such as indium oxide or tin oxide, or another appropriate conductive agent is used. be able to. Further, in order to improve the adhesive strength with the resistance adjusting layer 110BK and the workability, a surface layer made of a heat shrinkable tube can be used.

Materials for the gap tape constituting the gap holding member 113BK include metals such as aluminum, iron and nickel and oxides thereof, Fe--Ni alloy, stainless steel, Co--Al alloy, Ni steel, duralumin, monel, Metal alloys such as Inconel, polyethylene (P
E), olefin resins such as polypropylene (PP), polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytetrafluoroethylene (PTFE), and copolymers thereof (eg PFA, FEP), etc. Examples thereof include fluororesin and polyimide resin. In particular, it is preferable to use a material having a high releasability in which the toner is not easily fixed. When a conductive material is used as the gap tape, it is preferable that the surface of the gap tape is coated with an insulating layer or a half-resistor layer to insulate between the tape and the image carrier. Conductive support 101BK outside the photosensitive layer 102BK of the image carrier 40BK
In the case of abutting against, it is necessary to use insulating gap tape.

The thickness of the surface layer 111BK between the spacer portions 105BK is 1 to 20 .mu.m as described above.
It is preferably set to m. If the thickness of the surface layer 111BK is thicker than this, charging efficiency for the image bearing member may be lowered, and if the thickness is thinner than the above range,
There is a risk that the surface layer 111BK will be scraped off with time and toner will adhere to the charging member.

The resistance layer portion between both spacer portions 105BK is constructed so as not to come into contact with the image carrier 40BK, but it is quite conceivable that this portion will become soiled over time. Therefore, as shown in FIGS. 9 and 11, the charging member 6
It is advantageous to provide a cleaning member 115BK which contacts 0BK and cleans the charging member 60BK. The cleaning member may be fixedly supported immovably, but like the charging device 1BK of this example, the charging member 60BK may be used.
In the case where the cleaning member 115BK is configured as a rotating body, especially as a charging roller, the cleaning member 115BK is preferably supported so as to come into contact with the charging member 60BK and rotate together therewith. If the cleaning member 115BK is configured in this way, the surface of the charging member 60BK can be efficiently cleaned at low cost and in a small space without providing a drive device for the cleaning member 115BK.

As the cleaning member 115BK,
Although a sponge roller or the like can be used, if the cleaning member 115BK has a brush that contacts the charging member 60BK as shown in FIGS. 9 and 11, the peripheral surface of the charging member 60BK can be efficiently cleaned. be able to. In the illustrated example, the cleaning member 115
BK is configured as a brush roller having a brush. At that time, it is particularly preferable to use an electrostatic flocking brush among the brushes. By using such a brush, the toner can be efficiently scraped from the surface of the charging member, and the scraped toner can be gradually discharged to the outside of the brush.

Further, even when the cleaning member 115BK is constructed as a sponge roller, a brush roller, or other forms, the cleaning member 11BK is also formed.
When 5BK is supported so as to swing while sliding on the charging member 60BK, cleaning efficiency for the charging member 60BK can be improved. In the example shown in FIGS. 9 and 11, the cleaning member 115BK is configured to swing in the axial direction of the cleaning member 115BK as shown by the arrow while contacting the peripheral surface of the charging member 60BK. Resistance adjusting layer 1 of charging member 60BK
When 10BK is made of a high hardness material such as a hard resin, the swinging cleaning member 115BK strongly contacts the peripheral surface of the charging member 60BK, so that the cleaning efficiency of the peripheral surface can be particularly enhanced.

Charging devices 1Y, 1M, 1 of the second to fourth image forming means 18Y, 18M, 18C shown in FIGS. 6 and 7.
C is also configured in the same manner as the charging device 1BK of each example described above. Further, among the elements constituting each image forming means, at least the charging device and the image carrier charged by the charging device constitute a process cartridge 107BK integrally assembled as shown in FIG. If the process cartridge 107BK is configured to be detachably attached to the main body of the image forming apparatus, that is, the main body casing of the image forming unit 100 in the example shown in FIG. 6, the maintainability thereof can be improved.

Next, a more specific configuration of each element of each image forming means 18BK to 18C will be described again with respect to the first image forming means 1 as well.
8BK will be described as an example.

As shown in FIG. 8, the developing device 61BK has a developing case 70BK, and a dry developer (not shown) is accommodated in the developing case 70BK. Although a one-component developer can be used as this developer,
In the illustrated example, a two-component developer having a magnetic carrier and a non-magnetic toner is used. Inside the developing case 70BK, there are a stirring section 66BK provided with two screws 68BK and a developing section 67BK provided with a developing sleeve 65BK. The stirring section 66BK includes the developing section 67BK.
It occupies a position lower than BK.

The two screws 68BK are separated from each other by a partition plate 69BK except for both ends (see FIG. 17), and the developing case 70BK has a toner density sensor 7a.
1BK is attached. The developing sleeve 65BK is located facing the image carrier 40BK through the opening of the developing case 70BK, and is provided with a doctor blade 73BK whose tip is located close to the developing sleeve 65BK. The distance at the closest point between the doctor blade 73BK and the developing sleeve 65BK is, for example, 5
It is set to 00 μm.

The developing sleeve 65BK is made of a non-magnetic material and is driven to rotate clockwise in FIG. The diameter of the developing sleeve 65BK is, for example, 18 mm, and the outer peripheral surface thereof is subjected to sandblasting or a process of forming a plurality of grooves having a depth of 1 to several mm so that RZ falls within the range of 10 to 30 μm. Is formed in. A magnet 72BK is fixedly arranged inside the developing sleeve 65BK, and the magnet 72BK is not shown in the figure, but N ₁ , S ₁ , N ₂ , S from the position of the doctor blade 73BK in the rotation direction of the developing sleeve 65BK. ₂ ,
It has five magnetic poles of S ₃ . The magnet 72BK has the magnetic pole S ₁ side facing the image carrier 40BK.

The two-component developer in the developing case 70BK is circulated and conveyed while being agitated by the two screws 68BK,
Supply to the developing sleeve 65BK. Development sleeve 65B
The developer supplied to K is drawn and held by the magnet 72BK, and forms a magnetic brush on the developing sleeve 65BK. The magnetic brush is a developing sleeve 65B.
Along with the rotation of K, the doctor blade 73BK cuts the blade into an appropriate amount. The developer that has been cut off is returned to the stirring unit 66BK. Of the developer carried and carried by the current-feeding sleeve 65BK, toner is the developing sleeve 6
The image carrier 40 by the developing bias voltage applied to 5 BK.
The electrostatic latent image formed on the BK is transferred to the image carrier 40.
The electrostatic latent image on BK is visualized. The developer remaining on the developing sleeve 65BK after the visible image is formed is the magnet 72B.
When there is no magnetic force of K, the developing sleeve 65BK is separated from the developing sleeve 65BK and returns to the stirring section 66BK. By repeating this, when the toner density in the stirring section 66BK becomes low, the toner density sensor 71BK detects it and the toner is replenished to the stirring section 66BK.

Incidentally, in the illustrated example, the image carrier 40BK
Linear velocity of 200 mm / s, developing sleeve 65BK linear velocity of 2
It is set to 40 mm / s. The diameter of the image carrier 40BK is 50 m.
m, the developing sleeve 65BK has a diameter of 18 mm, and the developing process is performed. The charge amount of the toner on the developing sleeve 65BK is preferably in the range of -10 to -30 μC / g.
The developing gap, which is the gap between the image carrier 40BK and the developing sleeve 65BK, is 0.8 mm to 0.4 m as in the conventional case.
It can be set within the range of m, and it is possible to improve the developing efficiency by reducing the value.

In the image forming apparatus of this example, the photosensitive layer 1
The thickness of 02BK is 30 μm, the beam spot diameter of the optical system is 50 × 60 μm, and the light amount is 0.47 mW. Further, the charge (before exposure) potential V ₀ of the photosensitive layer 102BK of the image carrier 40BK is −700 V, and the post-exposure potential V _L is −.
The developing step is performed with the developing bias voltage of 120 V and the developing bias voltage of -470 V, that is, the developing potential of 350 V.

Cleaning device 63BK for image carrier
Has its tip pressed against the surface of the photosensitive layer of the image carrier 40BK,
For example, a cleaning blade 75 made of polyurethane rubber
Equipped with BK. A brush whose outer periphery is in contact with the surface of the image carrier is also used in order to improve the cleaning property. In this example, a conductive fur brush 7 whose outer periphery is in contact with the surface of the image carrier is used.
6BK is provided so as to be rotatable in the arrow direction. Further, the electric field roller 7 made of metal for applying a bias to the fur brush 76BK.
7BK is rotatably provided in the direction of the arrow, and the electric field roller 7
Press the tip of scraper 78BK against 7BK. Further, a recovery screw 79BK for recovering the removed toner is provided. Then, the fur brush 76BK rotating in the counter direction with respect to the surface of the image carrier removes the residual toner on the image carrier. The toner adhered to the fur brush 76BK contacts the fur brush 76BK in the counter direction, rotates, and is biased by the electric field roller 7.
Removed to 7BK. The toner attached to the electric field roller 77BK is cleaned by the scraper 78BK.
The toner collected by the cleaning device 63BK is moved to one side of the cleaning device 63BK by the recovery screw 79BK and is returned to the developing device 61BK by the toner recycling device 80BK described later for reuse.

Next, FIGS. 17 and 18 show a toner recycling device 80BK. As shown in FIG. 18, the recovery screw 79BK of the cleaning device 63BK (FIG. 8) for the image carrier is provided with a roller portion 82BK having a pin 81BK at one end. And the roller portion 82BK
Is hung on one side of the belt-shaped collected toner conveying member 83BK of the toner recycling device 80BK, and the pin 81BK is inserted into the long hole 84BK of the collected toner conveying member 83BK.
Blades 85BK are provided at regular intervals on the outer circumference of the collected toner conveying member 83BK, and a rotating shaft 86BK is provided on the other side.
It is hung on the roller portion 87BK of.

The collected toner conveying member 83BK has a rotary shaft 8
It is put together with 6BK in the conveyance path case 88BK shown in FIG. The transport path case 88BK is formed integrally with the cartridge case 89BK, and the two screws 6 of the developing device 61BK described above are attached to the end portion on the developing device 61BK side.
Put one of 8BK. Then, the driving force is transmitted from the outside to rotate the recovery screw 79BK, the recovery toner transfer member 83BK is rotationally transferred, and the toner recovered by the cleaning device 63BK is transferred to the transfer path case 88B.
It is conveyed to the developing device 61BK through the inside of K and screw 6
It is put into the developing device 61BK by rotating 8BK. afterwards,
As described above, the toner is supplied to the two screws 68B.
At K, the developer that is already in the developing device 61BK is conveyed and circulated while being stirred, and the developer is transferred to the developing sleeve 65.
After supplying to BK and cutting off the ears with the doctor blade 73BK, the toner is transferred to the image carrier 40BK to develop the electrostatic latent image on the image carrier 40BK.

The toner is formed by adding external additives such as base particles containing a binder resin, a colorant, and, if necessary, other materials such as a charge control agent and a release agent. .
As the binder resin used for the toner, conventionally known binder resins can be used, and examples thereof include polystyrene, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-acrylic acid ester copolymer, and styrene-methacryl. Acid ester copolymer, acrylic resin, polyester resin, epoxy resin, polyol resin, rosin-modified maleic acid resin, phenol resin, low molecular weight polyethylene,
Low molecular weight polypropylene, ionomer resins, polyurethane resins, ketone resins, ethylene-ethyl acrylate copolymers, polybutyral, silicone resins and the like can be mentioned, and these can be used alone or in combination of two or more, and particularly polyester. Resins and polyol resins are preferred.

Here, various types of polyester resins can be used, but in particular, at least one selected from divalent carboxylic acids, their lower alkyl esters and acid anhydrides. A diol component represented by the following general formula (I).

[Chemical 1] (In the formula, R ¹ and R ² may be the same or different and each is an alkylene group having 2 to 4 carbon atoms, and x and y are the number of repeating units, each being 1 or more, and x + y.
= 2 to 16). At least one selected from trivalent or higher polyvalent carboxylic acids, their lower alkyl esters and acid anhydrides, and trivalent or higher polyhydric alcohols. A polyester resin obtained by reacting the above with is preferable.

Examples of the divalent carboxylic acid, its lower alkyl ester and its acid anhydride include terephthalic acid, isophthalic acid, sebacic acid, isodecylsuccinic acid, maleic acid, fumaric acid, and their monomethyl and monoethyl groups. , Dimethyl and diethyl esters, and phthalic anhydride, maleic anhydride, etc., and terephthalic acid, isophthalic acid and these dimethyl esters are particularly preferable in terms of blocking resistance and cost. These two
The carboxylic acid, its lower alkyl ester and its acid anhydride greatly affect the fixing property and blocking resistance of the toner. That is, although depending on the degree of condensation, a large amount of aromatic terephthalic acid, isophthalic acid, or the like improves the blocking resistance but decreases the fixability. On the contrary, if sebacic acid, isodecylsuccinic acid, maleic acid, fumaric acid and the like are used in a large amount, the fixing property is improved, but the blocking resistance is lowered. Therefore, these divalent carboxylic acids are appropriately selected according to other monomer composition, ratio, and degree of condensation, and used alone or in combination.

An example of the diol component represented by the above general formula (I) is polyoxypropylene- (n)-
Polyoxyethylene- (n ')-2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene-
(N) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene- (n) -2,2-bis (4
-Hydroxyphenyl) propane and the like, but in particular, polyoxypropylene with 2.1 ≦ n ≦ 2.5
(N) -2,2-bis (4-hydroxyphenyl) propane and polyoxyethylene- (n) -2,2-bis (4-hydroxyphenyl) propane with 2.0 ≦ n ≦ 2.5 are preferred. .. Such a diol component has the advantages of improving the glass transition temperature and facilitating the control of the reaction.

As the diol component, an aliphatic diol such as ethylene glycol, diethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol or propylene glycol should be used. Is also possible.

Examples of the trivalent or higher valent polycarboxylic acids, their lower alkyl esters and acid anhydrides include
1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,3,5-benzenetricarboxylic acid, 1,2,
4-cyclohexanetricarboxylic acid, 2,5,7-naphthylenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,
2,5-hexatricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, tetra (methylenecarboxy) methane, 1,2,7,8-
Examples include octane tetracarboxylic acid, empol trimer acid and their monomethyl, monoethyl, dimethyl and diethyl esters.

Examples of the trihydric or higher polyhydric alcohol include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, and soy sauce. Sugar, 1,2,4-butanetriol, 1,2,
5-pentatriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,
2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like can be mentioned.

Here, the compounding ratio of the trivalent or higher polyvalent monomer is appropriately about 1 to 30 mol% of the total monomer composition. When it is 1 mol% or less, the offset resistance of the toner is lowered and the durability is apt to be deteriorated. On the other hand, when it is 30 mol% or more, the fixability of the toner tends to deteriorate.

Of these trivalent or higher polyvalent monomers, benzene tricarboxylic acids such as benzene tricarboxylic acid and anhydrides or esters of these acids are particularly preferable. That is, by using benzenetricarboxylic acids,
Both fixability and offset resistance can be achieved.

As the polyol resin, various types can be used. Particularly, an epoxy resin and
By reacting an alkylene oxide adduct of a dihydric phenol or its glycidyl ether, a compound having one active hydrogen in the molecule which reacts with an epoxy group, and a compound having two or more active hydrogens reacting with an epoxy group in a molecule It is preferable to use a polyol resin obtained from the above. Here, the epoxy resin is preferably obtained by binding bisphenol such as bisphenol A or bisphenol F and epichlorohydrin. Particularly, at least two kinds of bisphenol A having different number average molecular weights in order to obtain stable fixing characteristics and gloss of the epoxy resin.
Type epoxy resin, the number average molecular weight of low molecular weight component is 36
0 to 2000, and the number average molecular weight of the high molecular weight component is 3
It is preferably from 000 to 10,000. Further, the low molecular weight component is 20 to 50% by weight, and the high molecular weight component is 5 to 40%.
It is preferably in the weight%. When there are too many low molecular weight components, or when the molecular weight is lower than 360, there is a possibility that the gloss may be too high or the storage stability may be deteriorated. Further, if the amount of the high molecular weight component is too large, or if the molecular weight is higher than 10,000, the gloss may be insufficient and the fixability may be deteriorated.

Further, examples of the alkylene oxide adduct of dihydric phenol as the compound (1) include the following. That is, reaction products of ethylene oxide, propylene oxide, butylene oxide, and mixtures thereof with bisphenols such as bisphenol A and bisphenol F can be mentioned. The obtained adduct may be glycidylated with epichlorohydrin, β-methylepichlorohydrin or the like before use. Particularly preferred is diglycidyl ether of an alkylene oxide adduct of bisphenol A represented by the following formula (Formula 2).

[0113]

[Chemical 2] (In the formula, R is —CH ₂ —CH ₂ —, —CH ₂ —CH (C
H ₃ )-or —CH ₂ —CH ₂ —CH ₂ — group, and n and m are the number of repeating units, each being 1 or more, and n + m = 2 to 6. )

Further, the alkylene oxide adduct of dihydric phenol or its glycidyl ether is preferably contained in an amount of 10 to 40% by weight based on the polyol resin. If the amount is too small, problems such as curling may occur, and if n + m is 7 or more or the amount is too large, the gloss may be excessive or the storability may be deteriorated.

The compounds having one active hydrogen in the molecule which reacts with the epoxy group include monohydric phenols, secondary amines and carboxylic acids. The following are examples of monohydric phenols. That is, phenol, cresol, isopropylphenol, aminophenol, nonylphenol, dodecylphenol, xylenol, p-cumylphenol and the like can be mentioned. Examples of secondary amines include diethylamine, dipropylamine, dibutylamine, N-methyl (ethyl) piperazine, piperidine and the like. Examples of the carboxylic acids include propionic acid and caproic acid.

Examples of the compound having two or more active hydrogens that react with the epoxy group in the molecule include dihydric phenols, polyhydric phenols and polyhydric carboxylic acids. Examples of dihydric phenols include bisphenols such as bisphenol A and bisphenol F. Also,
Examples of polyphenols include orthocresol novolacs, phenol novolacs, tris (4-hydroxyphenyl) methane, and 1- [α-methyl-α- (4-hydroxyphenyl) ethyl] benzene. Examples of polyvalent carboxylic acids include malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, phthalic acid, terephthalic acid, trimellitic acid, and trimellitic anhydride.

Further, if these polyester resins and polyol resins have a high crosslink density, it becomes difficult to obtain transparency and glossiness. Therefore, it is preferable to use noncrosslinking or weak crosslinking (THF insoluble content is 5% or less. ) Is preferable. Further, the production method of these binder resins is not particularly limited, bulk polymerization, solution polymerization, emulsion polymerization,
Both suspension polymerization and the like can be used.

Next, as the colorant used for the toner, conventionally known dyes and pigments can be used. Examples of yellow colorants include Naphthol Yellow S, Hansa Yellow (10G, 5G, G), Cadmium Yellow,
Yellow iron oxide, ocher, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow, (GR, A, R
N, R), Pigment Yellow L, Benzidine Yellow (G, GR), Permanent Yellow (NCG), Balkan Fast Yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow B.
GL, benzimidazolone yellow, isoindolinone yellow and the like can be mentioned.

Examples of red colorants include red iron oxide, red lead, red lead, cadmium red, cadmium mercury red, antimony red and permanent red 4.
R, Para Red, Fire Red, Parachloro Ortho Nitroaniline Red, Resole Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R,
FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resor Rubin GX, Permanent Red (F5R, FBB), Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux. F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B,
Rhodamine lake Y, alizarin lake, thioindigo red B, thioindigo maroon, oil red, quinacridone red, pyrazolone red, polyazo red,
Examples include chrome vermilion, benzidine orange, perinone orange, and oil orange.

Examples of blue colorants include cobalt blue, cerulean blue, alkali blue lake, peacock blue lake, Victoria blue lake, metal-free phthalocyanine blue, phthalocyanine blue, fast sky blue, indanthrene blue (RS, B).
C), indigo, ultramarine, navy blue, anthraquinone blue,
Fast violet B, methyl violet rake,
Cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment green B, naphthol green B, green gold, acid green lake, malachite green lake, phthalocyanine green, anthraquinone green. Etc.

Examples of black colorants include azine dyes such as carbon black, oil furnace black, channel black, lamp black, acetylene black and aniline black, metal salt azo dyes, metal oxides, composite metal oxides and the like. Is mentioned. Examples of other colorants include titania, zinc white, lithobon, nigrosine dye, iron black and the like. These colorants may be used alone or in combination of two or more, and the content thereof is usually 1 to 30 parts by weight, preferably 3 to 20 parts by weight, based on 100 parts by weight of the binder resin.

If necessary, other materials such as a charge control agent and a release agent can be added to the toner.

Here, as the charge control agent, conventionally known ones can be used, and examples thereof include a nigrosine dye, a chromium-containing complex, a quaternary ammonium salt and the like, and these are properly used depending on the polarity of the toner particles. In particular, in the case of a color toner, a colorless or pale color toner that does not affect the color tone of the toner is preferable, and examples thereof include a metal salt of salicylic acid or a metal salt of a salicylic acid derivative (Bontron E84, manufactured by Orient). These charge control agents can be used alone or in combination of two or more kinds, and the content is usually 0.5 to 8 parts by weight, preferably 1 to 5 parts by weight with respect to 100 parts by weight of the binder resin. is there.

Further, in order to improve the releasability of the toner from the fixing member at the time of fixing and to improve the fixability of the toner, it is possible to include a releasing agent in the toner. Here, as the release agent, conventionally known release agents can be used, and examples thereof include low molecular weight polyolefin waxes such as low molecular weight polyethylene and low molecular weight polypropylene, synthetic hydrocarbon waxes such as Fischer-Tropsch wax, beeswax, carnauba. Natural waxes such as wax, candelilla wax, rice wax and montan wax, petroleum waxes such as paraffin wax and microcrystalline wax, higher fatty acids such as stearic acid, palmitic acid and myristic acid, and metal salts of higher fatty acids, higher fatty acids Examples thereof include amides and various modified waxes thereof. These releasing agents can be used alone or in combination of two or more kinds, and particularly by using carnauba wax, good releasing property can be obtained. The content of the release agent is usually 1 to 15 parts by weight, preferably 2 to 100 parts by weight of the binder resin.
10 parts by weight. If it is 1 part by weight or less, the offset prevention effect and the like are insufficient, and if it is 15 parts by weight or more, transferability, durability and the like are deteriorated.

Further, the toner may contain a magnetic material to be used as a magnetic toner. Specific magnetic materials include magnetite, hematite, iron oxides such as ferrite, cobalt, metals such as nickel, or these metals and aluminum, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium,
Examples thereof include alloys with metals such as calcium, manganese, selenium, titanium, tungsten and vanadium, and mixtures thereof. These magnetic materials have an average particle size of 0.1 to 0.1.
2 μm or so is preferable, and the content is 10
It is usually 20 to 200 parts by weight, preferably 40 to 150 parts by weight, based on 0 parts by weight.

Next, an example of toner production will be described below. The above-mentioned binder resin, colorant, and if necessary, charge control agent, release agent, magnetic substance, etc. are sufficiently mixed by a mixer such as a Henschel mixer. Batch type twin roll, Banbury mixer and continuous type twin screw extruder, for example, KTK twin screw extruder manufactured by Kobe Steel, TEM twin screw extruder manufactured by Toshiba Machine Co., KCK
Twin screw extruder manufactured by Ikegai, PCM twin screw extruder manufactured by Ikegai Iron Works, KEX twin screw extruder manufactured by Kurimoto Iron Works, and continuous single screw kneader, for example, heat kneading by Bus Co. The ingredients are thoroughly kneaded using a machine. After cooling the kneaded product, it is roughly crushed using a hammer mill, etc., and further finely crushed by a fine crusher using a jet stream or a mechanical crusher, and a classifier using a swirling air flow or a classifier using the Coanda effect. To classify the particles to a predetermined particle size to obtain base particles.

As other manufacturing method, it is also possible to use a polymerization method, a capsule method or the like. The outline of these manufacturing methods will be described below.

(Polymerization Method) A polymerizable monomer, and if necessary, a polymerization initiator and a colorant are granulated in an aqueous dispersion medium. The granulated monomer composition particles are classified into an appropriate particle size. The monomer composition particles having a specified inner diameter obtained by the above classification are polymerized. After appropriate treatment to remove the dispersant, the polymerization product obtained above is filtered, washed with water, and dried to obtain base particles.

(Capsule method) A resin and, if necessary, a colorant and the like are kneaded with a kneader or the like,
A toner core material in a molten state is obtained. The toner core material is put in water and stirred vigorously to form a particulate core material. The above-mentioned core material fine particles are put into a shell material solution, a poor solvent is dropped while stirring, and the core material surface is covered with a shell material to be encapsulated. The capsules obtained as described above are filtered and dried to obtain base particles.

Next, the mother particles and the additives were added to a Henschel mixer (manufactured by Mitsui Miike Co., Ltd.), a mechanofusion system (manufactured by Hosokawa Micron Co., Ltd.) and a mechanomill (manufactured by Okada Seiko Co., Ltd.)
Mix well with a mixer such as
After passing through a sieve with an opening of about m or less, aggregates and coarse particles are removed.

Here, conventionally known additives can be used as the additive, for example, Si, Ti, Al, Mg, Ca,
Sr, Ba, In, Ga, Ni, Mn, W, Fe, C
Examples thereof include oxides such as o, Zn, Cr, Mo, Cu, Ag, V, and Zr, and complex oxides. Particularly, Si, Ti, and Al oxides such as silica, titania, and alumina are preferably used. Further, the addition amount of the additive at this time is preferably 0.6 to 4.0 parts by weight, and particularly preferably 1.0 to 3.6 parts by weight with respect to 100 parts by weight of the base particles. is there. If the amount of the additive added is less than 0.6 parts by weight, the fluidity of the toner will be reduced, so that sufficient chargeability will not be obtained, and the transferability and heat-resistant storage stability will also be insufficient. It also easily causes scumming and toner scattering. On the other hand, if the amount is more than 4.0 parts by weight, the fluidity is improved, but the cleaning of the photosensitive member due to chattering, blade curling, etc.
Filming on the photoconductor or the like due to the additive released from the toner is likely to occur, the durability of the cleaning blade, the photoconductor or the like is deteriorated, and the fixing property is also deteriorated.

There are various methods for measuring the content of the additive, but the fluorescent X-ray analysis method is generally used. That is, for toner with a known additive content,
A calibration curve is prepared by a fluorescent X-ray analysis method, and the content of the additive can be determined using this calibration curve. Further, the additive is preferably subjected to a surface treatment for the purpose of making it hydrophobic, improving fluidity, controlling chargeability, etc., if necessary.

Here, the treating agent used for the surface treatment is preferably an organic silane compound or the like, and examples thereof include alkylchlorosilanes such as methyltrichlorosilane, octyltrichlorosilane and dimethyldichlorosilane, dimethyldimethoxysilane and octyltrimethoxysilane. Alkylmethoxysilanes such as hexamethyldisilazane,
Silicone oil etc. are mentioned. Further, as the treatment method, there are a method of immersing the additive in a solution containing an organic silane compound and drying, a method of spraying a solution containing the organic silane compound as an additive and drying, and either method. Can also be preferably used.

Further, the particle diameter of the additive added to the base particles is 0.0 in terms of average primary particle diameter from the viewpoint of fluidity and the like.
The thickness is preferably 02 to 0.2 μm, and particularly preferably 0.005 to 0.05 μm. Additives having an average primary particle size of less than 0.002 μm easily embed the additives on the surface of the base particles, so that aggregation easily occurs and sufficient fluidity cannot be obtained. Further, filming on the photoconductor or the like is likely to occur, and these tendencies are remarkable especially under high temperature and high humidity. In addition, if the average primary particle size is smaller than 0.002 μm, the additives tend to agglomerate with each other.
It becomes difficult to obtain sufficient fluidity. Additives having an average primary particle diameter of more than 0.2 μm reduce the fluidity of the toner, failing to obtain sufficient chargeability, and are apt to cause scumming and toner scattering. The average primary particle size is 0.1
Additives larger than μm tend to damage the surface of the photoreceptor,
It is also likely to cause filming. The particle size of the additive can be determined by measuring with a transmission electron microscope.

In addition to the above-mentioned additives, other additives may be added to the toner. Examples of such additives include Teflon (registered trademark), zinc stearate, and polyvinylidene fluoride as lubricants.
As an abrasive, cerium oxide, silicon carbide, strontium titanate and the like, as a conductivity imparting agent, zinc oxide,
Examples thereof include antimony oxide and tin oxide.

The particle diameter of the toner is 4 to 4 in terms of weight average diameter.
It is preferably 9 μm, particularly preferably 5 to 8
μm. Here, when the particle size is smaller than 4 μm,
In some cases, background stains and toner scattering may occur during development, and fluidity may be deteriorated to hinder toner replenishment and cleaning. Further, when the particle diameter is larger than 8 μm, dust in the image, deterioration of resolution, etc. may become a problem, and particularly in the case of a color image, the influence is great.

The toner can be applied to both one-component toner and two-component toner. In the case of a two-component toner, it is mixed with a carrier and used as a two-component developer. Here, as the carrier, conventionally known carriers can be used, and examples thereof include magnetic powder such as iron powder, ferrite powder, and nickel powder, and glass beads.
It is preferable to coat these surfaces with a resin or the like. In this case, examples of the resin used include polyfluorocarbon, polyvinyl chloride, polyvinylidene chloride, phenol resin, polyvinyl acetal, acrylic resin and silicone resin. Further, as a method of forming this resin layer, the resin may be applied to the surface of the carrier by means of a spraying method, a dipping method or the like as in the conventional case. The amount of the resin used is usually preferably 1 to 10 parts by weight with respect to 100 parts by weight of the carrier. The resin film thickness is preferably 0.02 to 2 μm, particularly preferably 0.05 to 1 μm.
m, and more preferably 0.1 to 0.6 μm. If the film thickness is large, the fluidity of the carrier and the developer tends to decrease, and if the film thickness is thin, it is affected by film scraping over time. It tends to be easy. Here, the average particle size of these carriers is usually 10 to 100 μm, preferably 30 to 60 μm. Further, the proper mixing ratio of the toner and the carrier is generally about 0.5 to 7.0 parts by weight of the toner to 100 parts by weight of the carrier.

Next, the production examples of the toner, the carrier and the developer will be described respectively, but the production examples are not limited to these examples. Parts in the following production examples represent parts by weight.

<Toner Production Example> Binder Resin Synthesized from polyester resin (terephthalic acid, fumaric acid, polyoxypropylene- (2,2) -2,2-bis (4-hydroxyphenyl) propane, trimellitic acid) Polyester resin, Tg: 62 ° C., softening point: 106 ° C.) 100 parts Colorant Pigment for yellow toner (disazo yellow pigment: CI. Pigment Yellow 17) 7.0 parts Pigment for magenta toner (quinacridone-based magenta pigment: CI. Pigment Red 122) 7.0 parts Cyan toner pigment (copper phthalocyanine blue pigment: CI. Pigment Blue 15: 3) 3.5 parts Black toner pigment (carbon black: CI. Pigment Black 7) 6.0 parts Charge control Agent Salicylic acid derivative zinc salt 2.5 parts Release agent Carnauba wax (melting point: 85 ° C) 5 parts The above raw materials are added to a Henschel mixer. After mixed,
Melt-kneading was performed with a twin-screw kneader set to 110 ° C. The kneaded product was cooled with water, coarsely pulverized with a cutter mill, pulverized with a fine pulverizer using a jet stream, and then mother particles were obtained using an air classifier.

Further, the above base particles 100 parts Additives Silica (hexamethyldisilazane surface-treated product, average primary particle size: 0.01 μm) 0.8 parts Titania (isobutyltrimethoxysilane surface-treated product, average primary particle size) : 0.015 μm) 1.0 part was mixed with a Henschel mixer, and then air-screened with a sieve having an opening of 100 μm to obtain a toner of Production Example (weight average diameter: 6.8 μm).

Here, the particle size distribution of the toner can be measured by various methods, but in this example, the Coulter Multisizer was used. That is, as the measuring device, a Coulter Multisizer IIe type (manufactured by Coulter) is used, and an interface for outputting the number distribution and the volume distribution
(Manufactured by Nikkaki Co., Ltd.) and a personal computer are connected,
As the electrolytic solution, a 1% NaCl aqueous solution was prepared using first-grade sodium chloride. As a measuring method, the electrolytic aqueous solution 100 is used.
A surface active agent, preferably 0.1 to 5 ml of alkylbenzene sulfonate, was added as a dispersant to 150 ml, and 2 to 20 mg of a measurement sample was further added, and a dispersion treatment was performed for about 1 to 3 minutes with an ultrasonic disperser. . Further, 100 to 200 ml of the electrolytic aqueous solution was put into another beaker, the sample dispersion liquid was added thereto to a predetermined concentration, and 100,000 apertures were used as an aperture by the Coulter Multisizer IIe type using 100 μm apertures. This was done by measuring the average of the particles.

<Production Example of Carrier> Core material Cu-Zn ferrite particles (weight average diameter: 45 μm) 5000 parts Coating material Toluene 450 parts Silicone resin SR2400 (manufactured by Toray Dow Corning Silicone, non-volatile content 50%) 450 parts Aminosilane SH6020 (Toray Dow Corning Silicone) 10 parts Carbon black 10 parts The above coating material is dispersed with a stirrer for 10 minutes to prepare a coating solution, and the coating solution and the core material are stirred in a fluidized bed with a rotary bottom plate disk. The coating liquid was put into a coating device for coating while forming a swirling flow provided with blades, and the coating liquid was applied onto the core material. Further, the obtained carrier was fired in an electric furnace at 250 ° C. for 2 hours to obtain a carrier (film thickness: 0.5 μm) of the production example.

<Production Example of Developer> Toner 5 of the above production example
And 95 parts of the carrier of the above Production Example were mixed with a Turbula mixer to obtain a developer.

By the way, the image forming apparatus includes a charging device,
The image carrier is charged by the charging device as described above. However, since the resistance layer portion between the spacer portions of the charging member is close to the surface of the image carrier, the charging member is discharged. Influences strongly on the photosensitive layer of the image bearing member, and the photosensitive layer may be deteriorated and the surface thereof may be easily scraped. In particular, when a voltage in which an alternating voltage is superimposed on a DC voltage is applied to the charging member, the photosensitive layer is easily scraped due to the influence of the frequency and the peak-to-peak voltage. If the photosensitive layer is scraped too much, good image formation cannot be performed. In addition, if the film thickness of the photosensitive layer is non-uniform, electric discharge may be concentrated on the non-uniform part and local abrasion of the surface of the photosensitive layer may occur. In order to avoid such a problem, there is a method of reducing the influence of the surface deterioration portion by increasing the thickness of the photosensitive layer, but if the thickness of the photosensitive layer is increased,
It is likely to be affected by environmental fluctuations and the thickness thereof tends to be uneven, which may cause unevenness in image density.

Therefore, the image bearing member 4 of the image forming apparatus of this example.
0BK has a surface layer containing a filler. For example, the filler of the photosensitive layer contains the filler so that it is difficult to be scraped with time. Such a surface layer is difficult to be abraded by the influence of discharge, and particularly when a voltage in which a DC voltage is superimposed with an AC voltage is applied to the charging member, good image formation can be performed for a long period of time. Next, a specific configuration example of the image carrier will be described.

FIGS. 19 to 22 are sectional views schematically showing an image carrier 40BK made of an electrophotographic photosensitive member. The image carrier 40BK shown in FIG. 19 is formed on the conductive support 101BK. A single-layer photosensitive layer 102BK mainly containing a charge generating substance and a charge transporting substance is provided. In this case, at least the surface of the photosensitive layer contains a filler. The image carrier 40BK shown in FIG.
01BK, a charge generation layer 117BK containing a charge generation substance as a main component and a charge transport layer 118BK containing a charge transport substance as a main component are laminated. In this case, at least the surface of the charge transport layer contains a filler. The image carrier 40BK shown in FIG. 21 has a single-layer photosensitive layer 102BK containing a charge-generating substance and a charge-transporting substance as main components on a conductive support 101BK, and a filler containing a filler on the surface of the photosensitive layer. A reinforcing charge transport layer 119BK is provided. The image carrier 40BK shown in FIG. 22 has a structure in which a charge generating layer 117BK containing a charge generating substance as a main component and a charge transporting layer 118BK containing a charge transporting substance as a main component are laminated on a conductive support 101BK. In addition, a filler-reinforced charge transport layer 119BK containing a filler is provided on the charge transport layer.

As the conductive support 101BK, one having a volume resistance of 10 ¹⁰ Ω · cm or less, for example,
Aluminum, nickel, chrome, nichrome, copper, gold,
Metals such as silver and platinum, metal oxides such as tin oxide and indium oxide, coated on film or cylindrical plastic or paper by vapor deposition or sputtering, or aluminum, aluminum alloy, nickel, stainless steel, etc. Extruding boards and them,
It is possible to use a tube that has been surface-treated by cutting, superfinishing, polishing, etc., after forming a raw tube by a method such as drawing. Further, the endless nickel belt and the endless stainless belt disclosed in JP-A-52-36016 can also be used as the conductive support.

In addition, the conductive support 101BK can be formed by coating the support with conductive powder dispersed in a suitable binder resin. As the conductive powder, carbon black, acetylene black, aluminum, nickel, iron, nichrome, copper,
Examples thereof include metal powders such as zinc and silver, and metal oxide powders such as conductive tin oxide. Further, the binder resin used at the same time, polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer , Polyvinyl acetate, polyvinylidene chloride, polyarylate resin,
Phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly-N-
Vinylcarbazole, acrylic resin, silicone resin,
Examples thereof include thermoplastic, thermosetting resin or photocurable resin such as epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin. Such a conductive layer can be provided by dispersing and coating the conductive powder and the binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone or toluene. Further, on a suitable cylindrical substrate, polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber,
A material obtained by providing a conductive layer with a heat-shrinkable tube containing the conductive powder in a material such as Teflon (registered trademark) can also be favorably used as the conductive support 101BK.

The photosensitive layer may be a single layer type in which a charge generating substance is dispersed in a charge transporting layer or a laminated type in which a charge generating layer and a charge transporting layer are sequentially laminated. Introduction Charge generation layer 117BK
A laminated type photoreceptor in which the charge transport layer 118BK and the charge transport layer 118BK are sequentially laminated will be described.

The charge generating layer is a layer containing a charge generating substance as a main component, and a binder resin may be used if necessary. An inorganic material and an organic material can be used as the charge generating substance. Examples of the inorganic material include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compounds, and amorphous silicon. As the amorphous silicon, those obtained by terminating dangling bonds with hydrogen atoms and halogen atoms, and those obtained by doping boron atoms, phosphorus atoms and the like are favorably used.

On the other hand, known materials can be used as the organic material. For example, phthalocyanine-based pigments such as metal phthalocyanine and metal-free phthalocyanine, azurenium salt pigment, squaric acid methine pigment, azo pigment having a carbazole skeleton, azo pigment having a triphenylamine skeleton, azo pigment having a diphenylamine skeleton, dibenzo. Azo pigments having a thiophene skeleton, azo pigments having a fluorenone skeleton, azo pigments having an oxadiazol skeleton, azo pigments having a bisstilbene skeleton, azo pigments having a distyryl oxadiazol skeleton, and distyryl carbazole skeletons Having azo pigment, perylene pigment, anthraquinone or polycyclic quinone pigment, quinone imine pigment, diphenylmethane and triphenylmethane pigment, benzoquinone and naphthoquinone pigment, cyanine and azomethine pigment, Jigoido pigments, bisbenzimidazo - such as Le based pigments. These charge generating substances can be used alone or as a mixture of two or more kinds.

The binder resin used in the charge generation layer as required includes polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, polyarylate, silicone resin, acrylic resin, polyvinyl butyral. , Polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinyl carbazole, polyacrylamide and the like are used. These binder resins can be used alone or as a mixture of two or more kinds. Further, a polymer charge transport material can be used as the binder resin of the charge generation layer. Furthermore, a low molecular weight charge transport material may be added if necessary. Charge transport materials that can be used in combination with the charge generation layer include electron transport materials and hole transport materials, and these include low molecular charge transport materials and polymer charge transport materials. Hereinafter, the polymer type charge transport material is referred to as a polymer charge transport material.

Examples of the electron transport material include chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4,5,7-tetranitroxanthone,
2,4,8-trinitrothioxanthone, 2,6,8-
Examples thereof include electron-accepting substances such as trinitro-4H-indeno [1,2-b] thiophen-4-one and 1,3,7-trinitrodibenzothiophene-5,5-dioxide. These electron transport materials can be used alone or as a mixture of two or more kinds.

Examples of the hole-transporting substance include the electron-donating substances shown below, which are preferably used. For example, oxazole derivative, oxadiazol derivative, imidazole derivative, triphenylamine derivative, 9-
(P-diethylaminostyrylanthracene), 1,1
-Bis- (4-dibenzylaminophenyl) propane,
Styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives,
Examples include acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives and the like. These hole transport materials can be used alone or as a mixture of two or more kinds.

Further, the polymer charge-transporting substances shown below can be used. For example, a polymer having a carbazole ring such as poly-N-vinylcarbazole, a polymer having a hydrazone structure exemplified in JP-A-57-78402, and an example in JP-A-63-285552. Polysilylene polymer to be used, JP-A-7-32540
Examples thereof include polymers having a triarylamine structure. These polymeric charge transport materials can be used alone or as a mixture of two or more.

The charge generating layer contains a charge generating substance, a solvent and a binder resin as main components, and includes any additives such as a sensitizer, a dispersant, a surfactant and a silicone oil. It may be.

As a method for forming the charge generating layer, a vacuum thin film forming method and a casting method from a solution dispersion system can be largely cited. The former method includes a vacuum deposition method, a glow discharge decomposition method, an ion plating method, a sputtering method,
A reactive sputtering method, a CVD method, or the like is used, and the above-mentioned inorganic material or organic material can be formed favorably. Further, in order to provide the charge generating layer by the casting method, the above-mentioned inorganic or organic charge generating substance is used with a binder resin together with tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone, and a ball mill using a solvent such as butanone, It can be formed by dispersing with an attritor, a sand mill, etc., and diluting the dispersion appropriately and applying. The coating can be performed using a dip coating method, a spray coating method, a bead coating method, or the like.

The thickness of the charge generation layer provided as described above is suitably about 0.01 to 5 μm, preferably 0.05 to 2 μm.

Next, the charge transport layer 118BK will be described. The charge transport layer can be formed by dissolving or dispersing a mixture or copolymer containing a charge transport component and a binder component as main components in a suitable solvent, and coating and drying the mixture. A suitable thickness of the charge transport layer is about 10 to 100 μm, and 10 to 30 μm when resolution is required.
The degree is appropriate. Examples of the polymer compound that can be used as the binder component include polystyrene,
Styrene / acrylonitrile copolymer, styrene / butadiene copolymer, styrene / maleic anhydride copolymer,
Polyester, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral,
Examples of the thermoplastic or thermosetting resin include polyvinyl formal, polyvinyl toluene, acrylic resin, silicone resin, fluororesin, epoxy resin, melamine resin, urethane resin, phenol resin, and alkyd resin.
It is not limited to these. These polymer compounds can be used alone or as a mixture of two or more kinds, or can be used by copolymerizing with a charge transport material.

Materials that can be used as the charge transport material include the above-mentioned low-molecular-weight electron transport material, hole transport material and polymer charge transport material. When a low molecular weight charge transport material is used, the amount used is the polymer compound 10
20 to 200 parts by weight, preferably 50 parts by weight, relative to 0 parts by weight
It is preferably about 100 parts by weight. When a polymer charge transport material is used, a material in which a resin component is copolymerized at a ratio of about 0 to 500 parts by weight with respect to 100 parts by weight of the charge transport component is preferably used.

Examples of the dispersion solvent that can be used when preparing the charge transport layer coating liquid include ketones such as methyl ethyl ketone, acetone, methyl isobutyl ketone and cyclohexanone, ethers such as dioxane, tetrahydrofuran and ethyl cellosolve, toluene, Examples thereof include aromatics such as xylene, halogens such as chlorobenzene and dichloromethane, and esters such as ethyl acetate and butyl acetate.

If the charge transport layer is not provided with the filler-reinforced charge transport layer 119BK described later, it is necessary to add a filler material to at least the surface portion of the charge transport layer for the purpose of improving abrasion resistance. As an organic filler material,
Fluororesin powder such as polytetrafluoroethylene,
Silicone resin powder, a-carbon powder, and the like,
As the inorganic filler material, metal powders such as copper, tin, aluminum and indium, silica, tin oxide, zinc oxide, titanium oxide, alumina, indium oxide, antimony oxide, bismuth oxide, calcium oxide and antimony are doped. Examples thereof include metal oxides such as tin oxide and indium oxide doped with tin, metal fluorides such as tin fluoride, calcium fluoride and aluminum fluoride, and inorganic materials such as potassium titanate and boron nitride. Among these fillers, it is advantageous to use an inorganic material from the viewpoint of hardness of the filler for improving wear resistance. In particular, silica, titanium oxide and alumina can be effectively used. These filler materials may be used alone or in combination of two or more. The filler surface may be modified with a surface treatment agent for the purpose of improving dispersibility in the coating liquid and the coating film.

These filler materials can be dispersed together with the charge transport substance, the binder resin, the solvent and the like by using an appropriate dispersing machine. The average primary particle size of the filler is
The thickness of 0.01 to 0.8 μm is preferable from the viewpoint of the transmittance and wear resistance of the charge transport layer. It is also possible to include these fillers in the entire charge transport layer, but since the exposed portion potential may be high, the outermost surface side of the charge transport layer has the highest filler concentration and the support side has a low value. It is preferable to provide a gradient in the filler concentration so that the charge transport layer has a plurality of layers and the filler concentration is gradually increased from the support side to the surface side. The thickness (depth from the surface) of the inorganic filler layer contained on the surface side of the charge transport layer is preferably 0.5 μm or more, more preferably 2 μm or more.

When the filler-reinforced charge transport layer is provided, the charge transport layer is prepared by dissolving or dispersing a mixture or copolymer containing the charge transport component and the binder component as the main components in a suitable solvent, and coating and drying the mixture. It can be formed by The film thickness of the charge transport layer is preferably about 10 to 100 μm, and when resolution is required, about 10 to 30 μm is suitable. Examples of the binder component that can be used in the charge transport layer in this case include the above-mentioned thermoplastic or thermosetting resins. These polymer compounds can be used alone or as a mixture of two or more kinds, or can be used by copolymerizing with a charge transport material.

Examples of the material that can be used as the charge transporting material include the aforementioned low molecular type electron transporting material, hole transporting material and polymer charge transporting material. Further, if necessary, suitable antioxidants, plasticizers, lubricants, ultraviolet absorbers, low molecular weight compounds such as low molecular weight charge transport substances, and leveling agents can be added. These compounds can be used alone or as a mixture of two or more kinds. The amount of the low molecular weight compound is 0.1 to 200 parts by weight, preferably 0.1 to 30 parts by weight, and the amount of the leveling agent is 100 parts by weight of the polymer compound. On the other hand, about 0.001 to 5 parts by weight is suitable.

Next, the filler-reinforced charge transport layer 119BK
Will be described. The filler-reinforced charge transport layer is a functional layer containing at least a charge transport component, a binder resin component and a filler and having both charge transportability and mechanical resistance. Filler-reinforced charge transport layers have the characteristic of exhibiting high charge mobilities comparable to conventional charge transport layers, which distinguishes them from surface protection layers. Further, the filler-reinforced charge transport layer is used as a surface layer obtained by functionally separating the charge transport layer in the multilayer type photoreceptor into two or more layers. That is, this layer is used in lamination with a charge transport layer containing no filler,
Never used alone. This distinguishes it from a single layer of charge transport layer where the filler is dispersed as an additive in the charge transport layer.

As the filler material used for the filler-reinforced charge transport layer, as described in the description of the charge transport layer,
Inorganic materials, especially silica, titanium oxide, and alumina can be effectively used. These filler materials may be used alone or in combination of two or more. For the purpose of improving the dispersibility in the coating liquid and the coating film, these fillers may be modified on the surface of the filler with a surface treatment agent as described above. These filler materials can be dispersed together with a charge transport substance, a binder resin, a solvent and the like by using an appropriate disperser. The average primary particle size of the filler is
The thickness of 0.01 to 0.8 μm is preferable from the viewpoint of the transmittance and wear resistance of the charge transport layer. As a coating method, a dipping method, a spray coating method, a ring coating method, a roll coater method, a gravure coating method, a nozzle coating method, a screen printing method or the like is adopted. The thickness of the filler-reinforced charge transport layer is preferably 0.5 μm or more, more preferably 2
It is preferably at least μm.

Next, the case where the photosensitive layer has a single layer structure 102BK will be described. The single-layer photosensitive layer can be formed by dissolving or dispersing the charge-generating substance, the charge-transporting substance and the binder resin in a suitable solvent, coating and drying the solution. If necessary, a plasticizer, a leveling agent, an antioxidant, etc. may be added. As the binder resin, in addition to the binder resin described above for the charge transport layer 118BK, the binder resin described for the charge generation layer 117BK may be mixed and used.
Of course, the above-mentioned polymer charge transport materials can also be used favorably. The amount of the charge generating substance is preferably 5 to 40 parts by weight, and the amount of the charge transporting substance is 0, relative to 100 parts by weight of the binder resin.
To 190 parts by weight is preferable, and more preferably 50 to 1
It is 50 parts by weight. The single-layer photosensitive layer is a dip coating method, a spray coating method, a beading method, in which a charge generating substance and a binder resin are dispersed together with a charge transporting substance in a dispersing machine using a solvent such as tetrahydrofuran, dioxane, dichloroethane and cyclohexane. It can be formed by coating with a coat or the like. The film thickness of the single-layer photosensitive layer is preferably about 5 to 25 μm. In the structure in which the photosensitive layer is the outermost surface layer, it is necessary to contain a filler at least on the surface of the photosensitive layer. Also in this case, as in the case of the charge transport layer, a filler may be contained in the entire photosensitive layer, but a filler concentration gradient may be provided or a constitution of a plurality of photosensitive layers may be used, in which the filler concentration is sequentially changed. It is an effective means to do.

Between the conductive support 101BK and the photosensitive layer
An undercoat layer can also be provided. The undercoat is generally a tree
The main component is oil, but these resins have a photosensitive layer on top of them.
Considering coating with a solvent, compared to general organic solvents
It is desirable that the resin has high solvent resistance. like this
Examples of such resins include polyvinyl alcohol, casein,
Water-soluble resin such as sodium acrylate, copolymer Nylo
Alcohol-soluble trees such as nylon and methoxymethylated nylon
Oil, polyurethane, melamine resin, phenol resin,
Lukid-three-dimensional mesh of melamine resin, epoxy resin, etc.
Examples include curable resins that form a structure. In addition, subduction
In order to prevent moire and reduce residual potential, the oxide layer has a titanium oxide layer.
Tan, silica, alumina, zirconium oxide, sulfur oxide
Fine powder of metal oxides that can be exemplified by nickel, indium oxide, etc.
Pigments may be added. These undercoat layers are formed by the above-mentioned photosensitive layer.
It can be formed as a layer using a suitable solvent and coating method.
it can. Further, as an undercoat layer, a silane coupling agent,
Titanium coupling agent, chrome coupling agent, etc. are used
You can also do it. In addition, the undercoat layer contains Al_TwoO _Three
Anodized, or polyparaxylylene (par
Organic materials such as rylene) and SiO_Two, SnO_Two, TiO_Two,
ITO, CeO_TwoInorganic substances such as are provided by the vacuum thin film forming method
It can also be used well. In addition to this
Can be used. The thickness of the undercoat layer is 0 to 20 μm
It is suitable, and preferably 1 to 10 μm.

In order to improve the environment resistance, and especially to prevent the sensitivity from lowering and the residual potential from rising, an antioxidant is added to each layer such as the charge generation layer, the charge transport layer, the undercoat layer, the protective layer and the intermediate layer. , A plasticizer, a lubricant, an ultraviolet absorber, a low molecular weight charge transport material and a leveling agent can be added. Representative materials for these compounds are described below.

Examples of the antioxidant that can be added to each layer include, but are not limited to, the followings. (A) Phenol compound 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, n-octadecyl -3- (4'-hydroxy
-3 ', 5'-di-t-butylphenol), 2,2'-methylene-bis- (4-methyl-6-t-butylphenol),
2,2'-methylene-bis- (4-ethyl-6-t-butylphenol), 4,4'-thiobis- (3-methyl-6-t-butylphenol), 4,4'-butylidenebis -(3-methyl-6-t-butylphenol),
1,1,3-tris- (2-methyl-4-hydroxy-
5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-
4-hydroxybenzyl) benzene, tetrakis- [methylene-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenyl) propionate] methane, bis [3.
3′-bis (4′-hydroxy-3′-t-butylphenyl) butyric acid) crycol ester, tocopherols and the like. (B) Para-phenylenediamines N-phenyl-N'-isopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl-p-
Phenylenediamine, N, N'-di-isopropyl-p
-Phenylenediamine, N, N'-dimethyl-N, N'-
Di-t-butyl-p-phenylenediamine and the like. (C) Hydroquinones 2,5-di-t-octylhydroquinone, 2,6-didodecylhydroquinone, 2-dodecylhydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t
-Octyl-5-methylhydroquinone, 2- (2-octadecenyl) -5-methylhydroquinone and the like. (D) Organic sulfur compounds dilauryl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, ditetradecyl-3,3'-thiodipropionate and the like. (E) Organophosphorus compounds Triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine and the like.

Examples of the plasticizer that can be added to each layer include, but are not limited to, the followings. (A) Phosphate ester plasticizer triphenyl phosphate, tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, trichloroethyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, tri-2-ethylhexyl phosphate, Triphenyl phosphate etc. (B) Phthalate ester plasticizers dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, diisooctyl phthalate, di-n-octyl phthalate, phthalate. Acid dinonyl, diisononyl phthalate, diisodecyl phthalate, diundecyl phthalate, ditridecyl phthalate, dicyclohexyl phthalate, butylbenzyl phthalate, butyllauryl phthalate, methyloleyl phthalate, octyldecyl phthalate, dibutyl fumarate, dioctyl fumarate Such. (C) Aromatic carboxylic acid ester-based plasticizer trioctyl trimellitate, tri-n trimellitate
-Octyl, octyl oxybenzoate and the like. (D) Aliphatic dibasic acid ester plasticizer dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, di-n-adipate
Octyl, adipic acid-n-octyl-n-decyl, diisodecyl adipate, dicapryl adipate, di-2-ethylhexyl azelate, dimethyl sebacate,
Diethyl sebacate, dibutyl sebacate, di-n-octyl sebacate, di-2-ethylhexyl sebacate, di-2-ethoxyethyl sebacate, dioctyl succinate, diisodecyl succinate, dioctyl tetrahydrophthalate, dihydrotetrahydrophthalate -N-octyl and the like. (E) Fatty acid ester derivative butyl oleate, glycerin monooleate, methyl acetylricinoleate, pentaerythritol ester, dipentaerythritol hexaester,
Triacetin, tributyrin, etc. (F) Oxyester plasticizers such as methyl acetylricinoleate, butyl acetylricinoleate, butylphthalylbutyl glycolate, and tributyl acetylcitrate. (G) Epoxy plasticizer Epoxidized soybean oil, epoxidized linseed oil, epoxy butyl stearate, decyl epoxy stearate, octyl epoxy stearate, benzyl epoxy stearate, dioctyl epoxy hexahydrophthalate, didecyl epoxy hexahydrophthalate, etc. . (H) Dihydric alcohol ester plasticizers such as diethylene glycol dibenzoate and triethylene glycol di-2-ethylbutyrate. (I) Chlorine-containing plasticizer Chlorinated paraffin, chlorinated diphenyl, chlorinated fatty acid methyl, methoxychlorinated fatty acid methyl, etc. (J) Polyester plasticizer polypropylene adipate, polypropylene sebacate, polyester, acetylated polyester and the like. (K) Sulfonic acid derivative p-toluene sulfonamide, o-toluene sulfonamide, p-toluene sulfone ethylamide, o-toluene sulfone ethylamide, toluene sulfone-N-ethylamide, p-toluene sulfone-N-cyclohexylamide and the like. (L) Citric acid derivative triethyl citrate, acetyl triethyl citrate, tributyl citrate, tributyl acetyl citrate, tri-2-ethylhexyl acetyl citrate, acetyl citrate-n-octyl decyl and the like. (M) Other terphenyls, partially hydrogenated terphenyls, camphor, 2
-Nitrodiphenyl, dinonylnaphthalene, methyl abietate and the like.

Examples of lubricants that can be added to each layer include, but are not limited to, the following. (A) Hydrocarbon compound Liquid paraffin, paraffin wax, microwax, low-polymerization polyethylene, etc. (B) Fatty acid compound lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid and the like. (C) Fatty acid amide compounds Stearyl amide, palmityl amide, olein amide, methylene bis stearamide, ethylene bis stearamide and the like. (D) Ester compound Lower alcohol ester of fatty acid, polyhydric alcohol ester of fatty acid, fatty acid polyglycol ester and the like. (E) Alcohol-based compounds cetyl alcohol, stearyl alcohol, ethylene glycol, polyethylene glycol, polyglycerol and the like. (F) Metal soaps Lead stearate, cadmium stearate, barium stearate, calcium stearate, zinc stearate, magnesium stearate and the like. (G) Natural wax carnauba wax, candelilla wax, beeswax, whale wax, ivorot wax, montan wax and the like. (H) Other silicone compounds, fluorine compounds and the like.

Examples of the ultraviolet absorber that can be added to each layer include, but are not limited to, the followings. (A) Benzophenone-based 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2 ', 4-trihydroxybenzophenone, 2,2', 4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4- Methoxybenzophenone etc. (B) Salsylate-based phenyl salicylate, 2,4 di-t-butylphenyl 3,5-di-t-butyl 4-hydroxybenzoate and the like. (C) benzotriazole-based (2′-hydroxyphenyl) benzotriazole,
(2'-hydroxy5'-methylphenyl) benzotriazole, (2'-hydroxy5'-methylphenyl) benzotriazole, (2'-hydroxy3'-tert-butyl5'-methylphenyl) 5-chlorobenzotriazole (D) Cyanoacrylate-based ethyl-2-cyano-3,3-diphenyl acrylate, methyl 2-carbomethoxy 3 (paramethoxy) acrylate and the like. (E) Quencher (metal complex salt system) Nickel (2,2 ′ thiobis (4-t-octyl) phenolate) n-butylamine, nickel dibutyldithiocarbamate, nickel dibutyldithiocarbamate, cobalt dicyclohexyldithiophosphate and the like. (F) HALS (hindered amine) bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2 -[3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionyloxy] ethyl] -4- [3- (3,5-
Di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpyridine,
8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2,4-dione, 4-benzoyloxy-2,
2,6,6-tetramethylpiperidine and the like.

Next, an example of manufacturing an image bearing member made of a photosensitive member will be described, but the invention is not limited to this.

2. A coating liquid for an undercoat layer, a coating liquid for a charge generation layer, and a coating liquid for a charge transport layer having the following compositions were successively applied and dried on an aluminum drum having a diameter of 30 mm.
5 μm undercoat layer, 0.2 μm charge generation layer, 28 μm
Was formed on the charge transport layer. The following inorganic filler coating liquid was pulverized (crushed) for 2 hours with a paint shaker using zirconia beads to obtain a coating liquid. This liquid was applied by spraying to provide a 1.5 μm filler-reinforced charge transport layer, and an electrophotographic photoreceptor was obtained. [Coating liquid for undercoat layer] Alkyd resin (Beckosol 1307-60-EL, manufactured by Dainippon Ink and Chemicals) 6 parts by weight Melamine resin (Super Beckamine G-821-60, manufactured by Dainippon Ink and Chemicals) 4 parts by weight Parts Titanium oxide (CR-EL manufactured by Ishihara Sangyo Co., Ltd.) 40 parts by weight Methyl ethyl ketone 200 parts by weight [Coating liquid for charge generation layer] Oxotitanium phthalocyanine pigment 2 parts by weight Polyvinyl butyral (UCC: XYHL) 0.2 parts by weight Tetrahydrofuran 50 parts by weight Parts [Coating liquid for charge transport layer] Polycarbonate resin (Z polycarbonate, viscosity average molecular weight: 50,000, manufactured by Teijin Chemicals Co., Ltd.) 12 parts by weight Low molecular charge transport material having a structure shown in (Chemical Formula 3) below

[Chemical 3] Tetrahydrofuran 100 parts by weight 1% silicone oil (KF50-100CS manufactured by Shin-Etsu Chemical Co., Ltd.) Tetrahydrofuran solution 1 part by weight [Filler reinforced charge transport layer coating liquid] Polycarbonate resin (Z polycarbonate, viscosity average molecular weight; 50,000, Teijin Chemicals Ltd.) 4 parts by weight) 3 parts by weight of a low molecular charge transport material having the structure shown below (Chemical Formula 4)

[Chemical 4] α-alumina (Sumicorundum AA-03, manufactured by Sumitomo Chemical Co., Ltd.) 0.7 parts by weight Cyclohexanone 280 parts by weight Tetrahydrofuran 80 parts by weight

The above is a specific configuration example of the image forming means.
Next, a specific configuration example of the endless belt-shaped intermediate transfer member 10 will be clarified.

For the intermediate transfer belt consisting of an endless belt, fluorine resin, polycarbonate resin, polyimide resin, etc. have been used conventionally, but in recent years all layers of the belt and
An elastic belt having a part of the belt as an elastic layer has been used. The transfer of a color image using a resin belt as an intermediate transfer member has the following problems.

A color image is usually formed by four color toners, and one to four toner layers are formed in one color image. The toner layer receives pressure by passing through the primary transfer position (transfer from the image carrier to the intermediate transfer member) and the secondary transfer position (transfer from the intermediate transfer member to the recording medium), and the cohesive force between the toners. Becomes higher. If the cohesive force between the toners becomes high, the phenomenon of hollow characters or missing edges of solid images is likely to occur.

Since the intermediate transfer member made of a resin belt has a high hardness and does not deform according to the toner layer, the toner layer is likely to be compressed and the hollow character of the character is likely to occur. Also,
Recently, there is an increasing demand for forming full-color images on various types of paper, for example, Japanese paper, or by intentionally forming unevenness on the paper or forming an image on the paper. However, paper with poor smoothness is likely to cause voids with the toner during transfer, which easily causes transfer omission. If the transfer pressure at the secondary transfer position is increased to improve the adhesion, the condensing force of the toner layer is increased,
The above-mentioned character dropout will occur.

On the other hand, since the elastic belt has a hardness lower than that of the resin belt, the elastic belt is deformed in the transfer portion in correspondence with the toner layer and the recording medium having poor smoothness. In other words, the elastic belt is deformed following local unevenness, so that good adhesiveness can be obtained without excessively increasing the transfer pressure to the toner layer, and there is no void in characters, and the paper has poor flatness. It is possible to obtain a transferred image with excellent uniformity.

For this reason, in the image forming apparatus of this example, the intermediate transfer member 10 shown in FIG. 16 is used as described above. In the intermediate transfer member 10 shown here, the base layer 11 is made of, for example, a fluororesin having a small elongation, a rubber material having a large elongation and a material which is hard to elongate such as canvas, and the elastic layer 12 is provided thereon. Elastic layer 12
Is made of, for example, fluorine rubber or acrylonitrile-butadiene copolymer rubber. The surface of the elastic layer 12 is
For example, the surface layer 13 having a good smoothness is formed by coating a fluorine resin. Specific examples of the material of each layer are as follows.

As the resin for the base layer 11, polycarbonate, fluororesin (ETFE, PVDF), polystyrene, chloropolystyrene, poly-α-methylstyrene, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene. -Vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer) , Styrene-octyl acrylate copolymer and styrene-phenyl acrylate copolymer), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene- Phenyl methacrylate copolymer etc.), styrene Styrene resins such as styrene-α-chloromethyl acrylate copolymer, styrene-acrylonitrile-acrylic acid ester copolymer (styrene or homopolymers containing styrene substitutes), methyl methacrylate resin, methacrylic acid Butyl acid acrylate resin, ethyl acrylate resin, butyl acrylate resin, modified acrylic resin (silicone modified acrylic resin, vinyl chloride resin modified acrylic resin, acrylic urethane resin, etc.), vinyl chloride resin, styrene-vinyl acetate copolymer, chlorinated Vinyl-vinyl acetate copolymer, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin, polyester polyurethane resin, polyethylene, polypropylene, polybutadiene, polyvinylidene chloride, ionomer resin, polyurethane resin, silicone Fat, ketone resins, ethylene - can be used ethyl acrylate copolymer, xylene resin and polyvinyl butyral resin, polyamide resin, one kind or two kinds or more selected from the group consisting of modified polyphenylene oxide resin. However, it goes without saying that the material is not limited to the above materials.

The elastic layer 12 is made of an elastomer.
Butyl rubber, fluorine rubber, acrylic rubber, EPDM,
NBR, acrylonitrile-butadiene-styrene rubber natural rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber, ethylene-propylene rubber, ethylene-propylene terpolymer, chloroprene rubber, chlorosulfonated polyethylene, chlorinated polyethylene, urethane rubber, syndiotactic Tic 1,2-polybutadiene, epichlorohydrin type rubber, recone rubber, fluororubber, polysulfide rubber, polynorbornene rubber, hydrogenated nitrile rubber, thermoplastic elastomer (for example, polystyrene type, polyolefin type, polyvinyl chloride type, polyurethane type) , Polyamide-based, polyurea-based, polyester-based, fluororesin-based) and the like. However, it goes without saying that the material is not limited to the above materials.

The surface layer 13 is required to reduce the adhesion of the toner to the surface of the intermediate transfer member to improve the secondary transfer property. For example, one or more kinds of polyurethane, polyester, epoxy resin, etc. are used to reduce surface energy and improve lubricity, for example, powder of fluororesin, fluorine compound, fluorocarbon, titanium dioxide, silicon carbide, etc. It is possible to disperse and use one kind or two or more kinds of particles or particles having different particle diameters. It is also possible to use a material such as a fluorine-based rubber material having a fluorine-rich layer formed on the surface by heat treatment to reduce the surface energy.

The resistance adjusting conductive agent used as necessary in the base layer 11, the elastic layer 12 or the surface layer 13 is, for example, carbon black, graphite, metal powder such as aluminum or nickel, tin oxide. , Titanium oxide, antimony oxide, indium oxide, potassium titanate, antimony oxide-tin oxide composite oxide (ATO), indium oxide-tin oxide composite oxide (ITO) and other conductive metal oxides, conductive metal oxides May be coated with insulating fine particles such as barium sulfate, magnesium silicate, and calcium carbonate. Of course, the conductive agent is not limited to the above.

[0187] The thickness of the elastic layer 12 depends on the hardness of the elastic layer, but if it is too thick, the expansion and contraction of the surface becomes large and cracks are likely to occur in the surface layer. In addition, it is not preferable that the thickness is too thick because the amount of expansion and contraction becomes large and the spread and bleeding in the image becomes large. Such a problem occurs when the thickness of the elastic layer is about 1 mm or more. The proper range of hardness of the elastic layer is 10 ° ≦ HS ≦ 65 ° (JIS-A). It is necessary to adjust the optimum hardness depending on the layer thickness of the belt. Hardness 10 ° JIS-
Those below A are very difficult to mold with high dimensional accuracy. This is because it is easily contracted and expanded during molding. Further, in the case of softening, it is a general method to add an oil component to the base material, but there is a drawback that the oil component exudes when continuously operated in a pressurized state. It was found that this contaminates the image carrier that comes into contact with the surface of the intermediate transfer member and causes lateral stripe unevenness. Generally, a surface layer is provided to improve releasability, but in order to provide a complete exudation prevention effect, the surface layer has high required quality such as durability quality, so it is necessary to select materials and secure characteristics. It will be difficult. On the other hand, those with a hardness of 65 ° JIS-A or higher can be molded with high precision due to the increased hardness, and it is possible to suppress or reduce the oil content. Although it can be reduced, the effect of improving transferability such as missing characters is not obtained, and it becomes difficult to stretch the roller.

The method for producing the intermediate transfer member is not limited, but the following method can be adopted, for example. A centrifugal molding method in which a material is poured into a rotating cylindrical mold to form a belt.
Spray coating method that forms a thin film on the surface. A dipping method in which a cylindrical mold is immersed in a solution of a material and pulled up.
Casting method to inject into the inner mold and the outer mold. There is a method of winding a compound around a cylindrical mold and performing vulcanization and polishing, but the method is not limited to this, and it is natural that a plurality of manufacturing methods can be combined to manufacture a belt.

Next, a specific example of the method for producing the intermediate transfer member will be described. Dip a cylindrical mold in a dispersion liquid in which 18 parts by weight of carbon black, 18 parts by weight of carbon black, 3 parts by weight of a dispersant, and 400 parts by weight of toluene are uniformly dispersed.
Gently pull up to dry at room temperature with 75μm PVD
A uniform film of F was formed. Repeat the mold on which the 75 μm film is formed and immerse the cylindrical mold in the solution under the above conditions.
Was gently pulled up at room temperature and dried at room temperature to form a 150 μm PVDF belt. To this, polyurethane prepolymer 1
00 parts by weight, curing agent (isocyanate) 3 parts by weight, carbon black 20 parts by weight, dispersant 3 parts by weight, MEK50
In a dispersion liquid in which 0 part by weight is uniformly dispersed,
The cylindrical mold on which the DF was formed was dipped, pulled up at 30 mm / sec, and naturally dried. After drying, the process was repeated to form a targeted 150 μm urethane polymer layer. Further, 100 parts by weight of the polyurethane prepolymer for the surface layer,
3 parts by weight of a curing agent (isocyanate), 50 parts by weight of PTFE fine powder powder, 4 parts by weight of a dispersant, and 500 parts by weight of MEK were uniformly dispersed. The cylindrical mold on which the urethane prepolymer of 150 μm was formed was dipped, pulled up at 30 mm / sec, and naturally dried. Repeat after drying 5μ
m of PTFE was uniformly dispersed to form a surface layer of a urethane polymer. After drying at room temperature, crosslinking was carried out at 130 ° C. for 2 hours to obtain a base layer; 150 μm, elastic layer;
Surface layer: A transfer belt having a three-layer structure of 5 μm was obtained.

In the above-mentioned intermediate transfer member, the expansion of the intermediate transfer member is prevented by forming the elastic layer on the base layer having a small elongation, but the core layer having the functions of the base layer and the elastic layer is formed. The intermediate transfer member on the belt can be constituted by the surface layer coated on the surface of the belt to prevent the intermediate transfer member from expanding. The core layer is composed of an elastic material and a material that prevents elongation. Examples of materials for the core layer that prevent elongation include natural fibers such as cotton and silk, polyester fibers, nylon fibers, acrylic fibers, polyolefin fibers, polyvinyl alcohol fibers, polyvinyl chloride fibers, polyvinylidene chloride fibers, polyurethane fibers. , One or more selected from the group consisting of synthetic fibers such as polyacetal fibers, polyfluoroethylene fibers and phenol fibers, inorganic fibers such as carbon fibers, glass fibers and boron fibers, and metal fibers such as iron fibers and copper fibers. Can be used in the form of woven cloth or thread. Of course, the material is not limited to the above.

The yarn may be any twisted yarn such as one or a plurality of filaments twisted, one-twisted yarn, ply-twisted yarn, twin yarn and the like. Further, for example, fibers of a material selected from the above material group may be mixed and spun. Of course, the thread may be used after being subjected to an appropriate conductive treatment. On the other hand, as the woven fabric, any woven fabric such as a knitted fabric can be used, and of course, a mixed woven fabric can also be used and naturally a conductive treatment can also be applied.

The core layer may be manufactured by, for example, covering a metal mold or the like with a tubular woven fabric and providing a covering layer made of an elastic material on the woven fabric, or a tubular woven fabric with a liquid rubber. A method of providing a coating layer on one side or both sides of the core layer by immersing the thread in a mold or the like, winding a thread spirally around a die or the like at an arbitrary pitch, and providing a coating layer made of an elastic material on it. You can

By the way, the cleaning device 17 for the intermediate transfer member shown in FIGS. 6 and 7 has two fur brushes 90 and 91 as cleaning members. The fur brushes 90, 91 have, for example, a diameter of 20.
mm, acrylic carbon, 6.25D / F, 100,000 pieces /
inch ² , 10 ⁷ Ω · cm is used, and the intermediate transfer member 10
It is provided so as to contact with and rotate in the counter direction. And, in each fur brush 90, 91,
Bias of different polarity is applied from a power source (not shown). The fur brushes 90, 91 are provided with metal rollers 92, 93 in contact therewith so as to rotate in forward or reverse directions. In this example, the intermediate transfer member 10
(-) Voltage is applied from the power supply 94 to the metal roller 92 on the upstream side in the rotation direction of the power supply 9 to the metal roller 93 on the downstream side.
A (+) voltage is applied from 5. Those metal rollers 9
The tips of the blades 96 and 97 are pressed against the blades 2 and 93, respectively. At the same time as the rotation of the intermediate transfer body 10 in the direction of the arrow, a (-) bias is first applied using the fur brush 90 on the upstream side to clean the surface of the intermediate transfer body 10. If -700 V is applied to the metal roller 92, the fur brush 90 becomes -400 V, and the (+) toner on the intermediate transfer body 10 is applied to the fur brush 9.
Transfers to the 0 side. The removed toner is further transferred from the fur brush 90 to the metal roller 92 due to the potential difference, and scraped off by the blade 96.

Although the toner on the intermediate transfer body 10 is removed by the fur brush 90, a large amount of toner remains on the intermediate transfer body 10. The toner is fur brush 9
By the (-) bias applied to 0, it is charged to (-). It is considered that this is charged by charge injection or discharge. However, the toner can be removed by subsequently applying the (+) bias with the fur brush 91 on the downstream side to perform cleaning. The removed toner transfers from the fur brush 91 to the metal roller 93 due to the potential difference, and the blade 97
To scrape off. The toner scraped off by the blades 96 and 97 is collected in a tank (not shown).

After cleaning with the fur brush 91, most of the toner is removed, but the intermediate transfer member 10
There is still some toner left on top. The toner remaining on the intermediate transfer body 10 is (+) by the (+) bias applied to the fur brush 91 as described above.
Be charged to. The toner charged to (+) is transferred to the image carrier side by the transfer electric field applied at the primary transfer position, and can be collected by the cleaning device for the image carrier. At the first primary transfer position, the toner is transferred to the most image carrier side. The order of colors forming an image on each image carrier is
The present invention is not limited to the above-mentioned example, but varies depending on the aim and characteristics of the image forming apparatus.

The registration roller 49 shown in FIGS. 6 and 7 is generally grounded and often used, but a bias can be applied to remove paper dust from the recording medium. . For example, a conductive rubber roller is used as the registration roller, and a bias is applied to this. More specifically, a conductive N having a diameter of 18 mm and a surface of 1 mm thick
BR rubber. Electric resistance is 10 in volume resistivity of rubber material
^The applied voltage is about −800 V on the toner transfer side (front side). A voltage of about +200 V is applied to the back side of the recording medium. In general, in the intermediate transfer method, the paper dust is difficult to move to the image carrier, so that it is not necessary to consider the paper dust transfer, and it may be grounded. Although a DC bias is applied as the applied voltage, this may be an AC voltage having a DC offset component in order to charge the recording medium more uniformly. The surface of the recording medium after passing through the resist roller 49 to which the bias is applied in this way is slightly charged to the negative side. Therefore, in the transfer from the intermediate transfer body 10 to the recording medium, the transfer condition may be changed and the transfer condition may be changed as compared with the case where the voltage is not applied to the registration roller 49.

As described above, an image forming apparatus for forming a toner image on one image carrier 40, and a plurality of image carriers 40BK, 40
Although the image forming apparatus of the type in which toner images of different colors are formed on Y, 40M, and 40C and the toner images are transferred to the intermediate transfer member has been described, the present invention is applicable to image forming apparatuses of various other types. Can also be applied. For example, an image forming apparatus of a type in which a synthetic toner image is formed on one image carrier and is transferred to a recording medium, toner images of different colors are sequentially formed on one image carrier, and the respective toner images are formed. An image forming apparatus of a type in which images are sequentially transferred to an intermediate transfer member, and a toner image of each color formed on a plurality of image carriers 40BK, 40Y, 40M, and 40C is conveyed by a sheet conveying belt 120 as shown in FIG. The present invention can be widely applied to an image forming apparatus of a type in which the toner images are sequentially transferred to the medium P and the transferred synthetic toner image is fixed by the fixing device 25. An image forming apparatus such as a printer or a facsimile, or at least two of an electronic copying machine, a printer, and a facsimile.
The present invention can also be applied to an image forming apparatus including a multifunction peripheral having two functions.

Incidentally, for reference, the image forming apparatus shown in FIG. 23 directly transfers the toner image on each image carrier to the recording medium, and is therefore called a direct transfer type image forming apparatus. There is. On the other hand, the image forming apparatus shown in FIG. 6 temporarily transfers the toner image on each image carrier to the intermediate transfer member, and then transfers the synthetic toner image on the intermediate transfer member to the recording medium. It is called an indirect transfer type image forming apparatus. In the former direct transfer type image forming apparatus, since the fixing device 25 is provided on the downstream side of the conveying belt 120 in the recording medium conveying direction, the image forming apparatus becomes large in the horizontal direction. On the other hand, in the latter image forming apparatus of the indirect transfer system, the secondary transfer position can be set relatively freely, and the fixing device 25 can be arranged below the intermediate transfer body 10, so that the image forming apparatus The horizontal size can be reduced. Further, in the former image forming apparatus, in order to prevent the image forming apparatus from increasing in size, it is necessary to dispose the fixing device 25 close to the conveyor belt 120. Therefore, the impact when the recording medium enters the fixing device 25 is large. However, in the case of the latter image forming apparatus, since the distance from the secondary transfer position to the fixing device 25 can be made large, the recording medium can be sent to the fixing device 25 with a margin, and the recording medium is fixed. It is possible to reduce the impact when entering the device 25.

[0199]

According to the present invention, since the image carrier is stopped after the application of the voltage to the charging member is turned off, the image forming operation is started and the image carrier is charged by the charging member. In this case, it is possible to prevent image deterioration caused by the absolute value of the surface potential of the image carrier portion facing the charging member being abnormally higher than that of the other image carrier portions when the image carrier is stopped. Moreover, it is possible to effectively suppress the generation of abnormal images due to the discharge products.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of an image carrier.

FIG. 2 is a view of the image carrier shown in FIG. 1 viewed in the direction of arrow II in FIG.

FIG. 3 is a diagram schematically illustrating a discharge region.

FIG. 4 is a timing chart showing an example of the off timing of voltage application to the charging member and the stop timing of the image carrier.

FIG. 5 is a timing chart showing another example of the off timing of the voltage application to the charging member and the stop timing of the image carrier.

FIG. 6 is a schematic cross-sectional view showing the overall configuration of the image forming apparatus.

FIG. 7 is a partially enlarged sectional view of FIG.

8 is a sectional view showing a part of FIG. 7 in a further enlarged manner.

FIG. 9 is a vertical sectional view of a charging member.

10 is an enlarged cross-sectional view showing a part of the charging member shown in FIG.

FIG. 11 is a vertical cross-sectional view showing another example of the charging member.

12 is an enlarged sectional view showing a part of the charging member shown in FIG.

FIG. 13 is a partial cross-sectional view of a charging member of another example.

FIG. 14 is a partial cross-sectional view of a charging member according to still another example.

FIG. 15 is a sectional view of a part of a charging member of still another example.

FIG. 16 is an enlarged cross-sectional view of an intermediate transfer member.

FIG. 17 is a cutaway perspective view of a process cartridge.

FIG. 18 is an exploded perspective view illustrating a toner recycling device.

FIG. 19 is a cross-sectional view illustrating the structure of an image carrier.

FIG. 20 is a cross-sectional view illustrating the structure of an image carrier.

FIG. 21 is a cross-sectional view illustrating the structure of an image carrier.

FIG. 22 is a cross-sectional view illustrating the structure of an image carrier.

FIG. 23 is a cross-sectional view showing another example of the image forming apparatus.

[Explanation of symbols]

40 image carrier 40BK image carrier 40Y image carrier 40M image carrier 40C image carrier 60 charging member P recording medium W1 charging area width

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H027 ED02 ED03 EE07 EF13 FA35                 2H200 FA03 FA07 FA19 GA12 GA14                       GA16 GA23 GA34 GA45 GA47                       GA53 GA56 GA59 GB02 GB12                       GB13 GB25 HA14 HA29 HB12                       HB22 HB43 HB45 HB46 HB48                       JA03 JB07 JB16 JB20 JC04                       JC13 JC15 JC17 LB12 LC03                       LC08 MA03 MA12 MA14 MA17                       MA20 MB04 MC01 MC02 NA02                       NA06 PA03 PA10 PA26

Claims (6)

[Claims] 1. An electrostatic latent image is formed on the charged image bearing member by applying a voltage to a charging member disposed opposite to the image bearing member to charge the image bearing member, and the electrostatic latent image is formed. In an image forming apparatus which visualizes a visible image and transfers the visible image to a recording medium directly or through an intermediate transfer body to obtain a recorded image, in stopping the image carrier, a voltage applied to the charging member. An image forming apparatus characterized in that the image carrier is stopped after the application is turned off. 2. After the voltage application to the charging member is turned off, the surface of the image carrier is moved at least by the width of the discharge region in the moving direction of the surface of the image carrier, and then the image carrier is stopped. The image forming apparatus according to claim 1. 3. The image forming apparatus according to claim 1, wherein the charging member is positioned such that an intermediate region between respective end regions in the longitudinal direction is separated from the surface of the image carrier. 4. The image forming apparatus according to claim 1, wherein the charging member is a charging roller that rotates in association with movement of the surface of the image carrier. 5. The voltage applied to the charging member is a voltage obtained by superimposing an alternating voltage on a DC voltage, and when the image carrier is stopped, after the application of the alternating voltage to the charging member is turned off, Turning off the application of a DC voltage to the charging member,
Next, the image forming apparatus according to claim 1, wherein the image carrier is stopped. 6. The linear velocity on the surface of the image carrier can be switched in at least two steps, and the linear velocity on the surface of the image carrier is V.
The image forming mode when it is 1 is the first mode, the image forming mode when the linear velocity of the image carrier surface is V2 which is higher than V1 is the second mode, and the charging is performed in the first mode. The time from turning off the application of the voltage to the member to the stop of the image carrier is T1, and the time from turning off the application of the voltage to the charging member to the stop of the image carrier in the second mode. 6. The image forming apparatus according to claim 1, wherein the off timing of voltage application to the charging member and the stop timing of the image carrier are controlled so that T1> T2, where T1> T2.