JPH11184263A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing an image defect in consequence of the excessive electric discharge on the upstream side of a contact part in transferring, enhancing transfer efficiency, improving the attracting force in attraction of recording material, restraining the attracting force from deterioration under the high humidity environment, limiting the attracting stage for thick paper to one process, and so on, in consequence of the electrification adopting an electrifying member of contact system electrifying means extending while coming into contact with a body to be electrified. SOLUTION: This contact system electrifying means 30 is, consisting by mounting a blade 34 composed of the conductive blade as a transfer electrifying member on an electrode 32, and the blade 34 is oriented to a transfer drum 8, for instance, extended on the slant from the upstream side to the downstream side in the moving direction the transfer drum 8, and held in contact with the photosensitive drum 1 by a corner part on the upstream side of a tip part across the transfer drum 8. By defining the contact angle (α) formed by a tangent at the contact part of the transfer drum 8 and the blade 34 as (α)=45 deg., and the tip angle (β) on a corner part of the blade 34 as (β)=130 deg., (α)+(β) is controlled within a range from 160 deg. to 180 deg..

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus employing an electrophotographic system or an electrostatic recording system.

[0002]

2. Description of the Related Art FIG. 8 shows the structure of a color copying machine as an example of a conventional image forming apparatus.

In the illustrated color copying machine, a photosensitive drum 1, which is an image carrier, is rotatably supported in an image forming section so as to rotate in the direction of the arrow in the figure, and an image forming means is disposed around the photosensitive drum. .

An exposure lamp 2 is provided around the photosensitive drum 1.
1, a primary charger 2, a light source device (not shown), a polygon mirror (not shown) for scanning light from the light source device, and a potential sensor (not shown) for detecting the surface potential of the photosensitive drum 1. is set up.

The light source device emits light corresponding to the image signal of each color component, scans the light by rotating a polygon mirror, deflects the light beam of the scanning light by a reflection mirror, and exposes the light beam through an fθ lens. The light is condensed on the generatrix of the drum 1, and an electrostatic latent image of each color component according to an image signal is sequentially formed on the photosensitive drum 1.

A developing device 3 is provided beside the photosensitive drum 1. The developing device 3 includes a magenta developing device 3a, a cyan developing device 3b, a yellow developing device 3c, and a black developing device 3d. These developing devices 3a, 3b, 3c
And 3d are filled with a predetermined amount of developer of yellow, magenta, cyan and black, respectively, by a supply device. The developing devices 3 a to 3 d are moved to a developing position facing the outer peripheral surface of the photosensitive drum 1 to develop the electrostatic latent image formed on the photosensitive drum 1.

A transfer drum 8 which is a recording material carrier is installed obliquely below the photosensitive drum 1. The recording material 6 is conveyed to the transfer drum 8 from a recording material cassette 60 provided on a side portion of the image forming apparatus main body via a registration roller 13 and the like. The transfer drum 8 is formed by joining a resin film of polyethylene terephthalate, polyvinylidene fluoride, polycarbonate, polyurethane, or the like to a frame body in which two rings are connected by a connecting member, thereby forming a drum shape.

The overall operation of the color image forming apparatus is described as 4
A brief description will be given by taking the case of color image formation as an example. The photosensitive drum 1 rotates, and its surface is uniformly charged by the charger 2. Next, a laser beam modulated by an image signal of the first color of a document (not shown), for example, a magenta image, is applied to the photosensitive drum 1 to form a magenta electrostatic latent image on the photosensitive drum 1. Then, the latent image is developed by a magenta developing device 3 a fixed at a developing position in advance to form a first magenta toner image on the photosensitive drum 1.

On the other hand, the recording material 6 is extruded from the cassette 60 by the registration roller 13 or the like in a direction along the transfer drum 8. Simultaneously with the extrusion of the recording material 6, an attraction voltage is applied from a power supply (not shown) to the attraction / charging member 44 of the attraction / charging means 40 to press the attraction / charging member 44 against the back surface of the transfer drum 8 and further to serve as a counter electrode thereof. By pressing the suction roller 46 as a ground member against the front surface of the transfer drum 8, the transfer drum 8 is attracted and charged from the back side, and the recording material 6 is electrostatically carried on the transfer drum 8. The transfer drum 8 rotates in the direction of the arrow in synchronization with the photosensitive drum 1, and the recording material 6 is conveyed to an image transfer unit where the photosensitive drum 1 and the transfer drum 8 face each other.

At a position inside the image transfer portion of the transfer drum 8, a contact type transfer charging means 30 is provided. As shown in FIG. 9, the contact-type transfer charging means 30
As a transfer charging member, a base (blade) 34 made of a conductive plate having a thickness direction in a plane parallel to the moving direction of the transfer drum 8 is attached. The conductive blade 34 extends toward the transfer drum 8 while being inclined, for example, from the upstream side to the downstream side in the movement direction of the transfer drum 8, and extends through the transfer drum 8 at the corner of the upstream angle β. 1 at an inclination angle α (an angle formed by the blade 34 with respect to a tangent at a contact portion on the surface of the photosensitive drum 1).

The recording material 6 conveyed to the image transfer section applies a transfer voltage to the blade 34 via the electrode 32 by a transfer power supply (not shown), so that the magenta toner image on the photosensitive drum 1 is formed while passing therethrough. Transcribed. The transfer drum 8 continues to rotate, and prepares for the transfer of the next second color cyan toner image.

When the transfer of the magenta toner image is completed, the transfer residual toner on the photosensitive drum 1 is cleaned by the cleaning member 5, and then the charging by the charger 2 and the irradiation of the laser beam are performed similarly. A cyan toner image of the next second color is formed on 1, and the cyan toner image is transferred onto the recording material 6 by being superimposed on the magenta toner image. A similar image forming process is performed for the third color, yellow and black, so that
A color image in which color toner images are superimposed and transferred is obtained.

The recording material 6 to which the four color toner images have been transferred is
The sheet is separated from the transfer drum 8 by the action of the separation claw, and is sent to the fixing device 7 by a conveyor belt or the like.

The fixing device 7 includes a fixing roller 71, a pressure roller 72, and heat-resistant cleaning members 73 and 74 thereof.
And heaters 75 and 76 housed in the fixing roller 71 and the pressure roller 72, an application roller 77 that applies a release agent oil such as dimethyl silicone oil to the fixing roller 71, and supplies the release agent oil. Oil reservoir 78
And a thermistor 79 for controlling the fixing temperature. The fixing device 7 fixes the conveyed recording material 6 to a fixing roller 7.
1 and the pressure roller 72 heat and pressurize to mix and fix the toner images of each color to the recording material 6 to form a full-color print image.

The toner remaining on the transfer drum 8 is neutralized by static eliminators 14 and 15 to remove electrostatic attraction, and then scraped off by a rotating fur brush 16. As a means for removing the residual toner, a blade or a nonwoven fabric is used alone or in combination.

In such a configuration, in order to transfer the toner image on the photosensitive drum 1 to the recording material 6 faithfully, the recording material 6 is placed at the contact point between the transfer drum 8 of the image transfer section and the photosensitive drum 1.
The transfer electric field is shielded near the upstream side of the contact point between the photosensitive drum and the transfer drum, when the side where the recording material enters from the contact point is the downstream side and the side where the recording material comes out from the contact point is the downstream side. According to this, toner particles are prevented from scattering from the toner image on the photosensitive drum, and the toner image can be faithfully transferred onto the recording material.

For these reasons, it has been widely practiced to provide an electric field regulating member upstream of the transfer charging means. For example, as shown in FIG. 9 above, an electric field regulating member 36 is provided on the side surface on the upstream side of the conductive blade 34 of the contact-type transfer charging means 30, and the transfer charging means is, as shown in FIG. In the case of the corotron charger 62, which is a transfer charging unit, an electric field regulating member 66 is provided upstream of the charger 62.

[0018]

However, as shown in FIG. 9, the angle (tip angle) of the corner on the upstream side of the blade 34, which comes into contact with the photosensitive drum 1 via the transfer drum 8, is provided.
β and a contact angle α formed by the blade 34 with respect to a tangent at a contact portion of the surface of the photosensitive drum 1 are conventionally α = 45.
゜ to 60 ° and β = 90 °, the blade 3
The discharge regions 201 and 202 formed on the upstream and downstream sides of the contact portion with the photosensitive drum 1 of No. 4 have a width of 180 to 210 μm.
They are formed almost equally in degree.

For this reason, an excessive discharge occurs on the upstream side where the potential difference between the back surface of the transfer sheet constituting the transfer drum 8 and the conductive blade 34 is large, causing transfer failure. Further, as the speed of the image forming apparatus increases, the charging time is insufficient with the above-described discharge region width, which causes a decrease in transfer efficiency.

A similar problem caused by excessive discharge at the upstream side of the contact portion also occurs in the attraction / charging member 42 for attracting the recording material to the transfer drum 8, which causes a decrease in the attraction force.

Further, in the case of recording material adsorption, there is a problem that the adsorption force is originally reduced in a high humidity environment, for example, at a temperature of 30 ° C. and a humidity of 80%. In addition, basis weight 128 g / m ²
In the above-described thick paper, a sufficient suction force cannot be ensured by one suction stroke, so that the suction force is obtained by the two suction strokes, and therefore, the image output of the thick paper takes longer than usual. There is also.

Accordingly, it is an object of the present invention to provide an image forming apparatus, which uses a charging member of a contact-type charging unit that extends and contacts an object to be charged, thereby preventing image defects due to excessive discharge upstream of the contacting portion in transfer. It is possible to improve the transfer efficiency by improving the suction force of the recording material, preventing the decrease in the suction force in a high humidity environment, and completing the suction stroke of the thick paper only once. Another object of the present invention is to provide an image forming apparatus capable of shortening an image output time.

[0023]

The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention provides:
An image carrier on which a toner image is formed, a recording material carrier that carries and conveys the recording material to the image carrier, moves while contacting the image carrier, and a conductive material that contacts the recording material carrier. A charging member having a substrate, wherein the conductive substrate has a plate-like shape having a thickness direction in a plane parallel to a moving direction of the recording material carrier, and the plate-like conductive substrate is provided with a recording member. In the image forming apparatus extending in the direction of the material carrier and contacting the same,
A tangent at a contact portion of the recording material carrier with the conductive substrate, a contact angle α between the conductive substrate and the tip angle β of a corner of the contact portion of the conductive substrate with the recording material carrier. The sum α + β with
An image forming apparatus, wherein the angle is 160 ° or more and 180 ° or less.

According to one aspect of the present invention, the charging member is configured such that the conductive base is in contact with the image carrier via the recording material carrier to carry the toner image formed on the image carrier. This is a transfer charging member for transferring onto a recording material carried on a body. According to another aspect of the present invention, the charging member is an adsorption charging member in which the conductive substrate is in contact with the ground member via the recording material carrier to adsorb the recording material to the recording material carrier.
The ground member was grounded via a resistor. A lubricating layer was provided on at least the contact portion side of the conductive substrate.

According to the present invention, there is provided a first image carrier on which a toner image is formed, and a second image carrier, to which the toner image is transferred from the first image carrier, which moves while being in contact with the image carrier. An image carrier; and a conductive substrate that transfers the toner image on the first image carrier to the second image carrier and that is in contact with the first image carrier via the second image carrier. A charging member, and the conductive substrate has a plate-like shape having a thickness direction in a plane parallel to a moving direction of the recording material carrier, and the plate-like conductive substrate is provided with a second image. In an image forming apparatus extending in the direction of a carrier and abutting on a first image carrier via a second image carrier, a tangent line at a contact portion of the first image carrier with a conductive substrate is provided. Sum of the contact angle α between the conductive substrate and the tip angle β of the corner of the conductive substrate in contact with the first image carrier.
The image forming apparatus is characterized in that + β is not less than 160 ° and not more than 180 °.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Embodiment 1 FIG. 1 is a sectional view showing an image transfer section in an embodiment of the image forming apparatus of the present invention, and shows the most general example of a charging member in the present invention. In this embodiment, a case where the charging member is applied to a transfer charging unit of the conventional color electrophotographic recording apparatus shown in FIG. 8 will be described.

Contact type transfer charging means 30 shown in FIG.
Has a base (blade) 34 made of a conductive plate having a thickness direction in a plane parallel to the moving direction of the transfer drum 8 attached to the electrode 32 as a transfer charging member. The transfer drum 8 is inclined from the upstream side to the downstream side in the moving direction of the transfer drum 8, extends toward the transfer drum 8, and is in contact with the photosensitive drum 1 via the transfer drum 8. A regulating member 36 for regulating the transfer electric field on the upstream side is provided on the upstream side surface of the blade 34.

Further, in order to prevent frictional deterioration of the contact portion of the blade 34 with the transfer drum 8, a lubricating layer 37 is provided at least on the upstream side of the contact portion of the blade 34 with the transfer drum 8. In this embodiment, polyamide 6 (nylon 6) is used for the lubricating layer 37, but other lubricants can be used.

The conductive blade 34 has an angle β at the corner on the upstream side of the tip, that is, the angle of the contact portion (tip angle), and makes an angle with the tangent at the contact portion of the photosensitive drum 1. The angle (contact angle) has an angle α. In order to prevent excessive discharge on the upstream side of the contact portion of the conductive blade 34 to prevent image defects due to excessive discharge on the upstream side and improve transfer efficiency, the contact angle α of the conductive blade 34
It is preferable that the sum α + β of the tip angles β is large. In the present invention, α + β is set to be not less than 160 ° and not more than 180 °. In particular, it is optimal that the angle is 170 ° or more and 175 ° or less.

The conductive blades 34 are made of SBR, BR, E
PDM, PV, Si rubber, chloroprene, epichlorohydrin rubber, etc. have carbon black, pigment, etc. added as a conductive filler, and the electrical resistivity is in the range of 10 ² to 10 ¹⁰ Ωcm by adding the conductive filler. Is controlled to any value. The hardness of the blade 34 is J
It is preferable that IS-A is in the range of 20 ° to 80 °, and in particular, that of 40 ° to 65 ° is optimal.

In this embodiment, the material of the blade 34 is a conductive epichlorohydrin rubber, and the electrical resistivity is 10 ⁶ Ωc.
m, hardness 62 ° (JIS-A), thickness 1.5 mm, contact angle α = 45 °, and tip angle β = 130 ° (α
+ Β = 175 °).

In the conventional blade 34, as shown in FIG. 9, the sum of the contact angle α and the tip angle β when contacting the photosensitive drum 1 via the transfer drum 8 is not large. Discharge areas 201 and 202 are formed on the upstream and downstream sides of the contact portion with the photosensitive drum 1 to have a width of about 200 μm, and excessive discharge occurs on the upstream side, which causes a defective transfer image. Also, as the speed of the image forming apparatus increases,
With the above-described discharge region width, the charging time is insufficient and the transfer efficiency is reduced.

FIG. 2 shows the temperature of 23 ° C. when the conductive blade of the first embodiment and the conventional conductive blade are used.
5 shows a curve (ID curve) of an image density change with respect to a transfer current in a low humidity environment with a humidity of 5%. Recording material 8 immediately after opening
0 g / m ² paper was used. The image density is a value obtained by forming a single-color solid image and measuring it using a density measuring device X-Rite404 (registered trademark).

As shown in FIG. 2, when the conductive blade of this embodiment is used, transfer efficiency is improved, and transfer efficiency and image density can be increased even with a low transfer current.

As described above, according to this embodiment, the necessary transfer current value can be reduced in order to obtain the same density as in the prior art. In addition, for the reasons described above, it is not sufficient to simply define the angle β of the corner of the tip of the blade 34 in order to define the discharge amount on the upstream and downstream sides of the contact portion of the blade 34. Defining the angle α is not enough,
It can be seen that it is necessary to define the total amount of α and β.

Conventionally, when the transfer current value is increased in order to improve the transfer efficiency, local abnormal discharge is caused, and a bubble-like white spot may appear on an image. Therefore,
By adopting the configuration as in the present embodiment, the transfer current value can be set to a low value, and there is also an effect that abnormal images such as bubble-like white spots can be avoided.

Embodiment 2 In this embodiment, as shown in FIG. 3, the conductive blade 34 of the transfer charging means 30 is moved from the counter direction with respect to the moving direction of the transfer drum 8 through the transfer drum 8 to the photosensitive drum 1.
Contacted.

In this case, as in the first embodiment, the blade 3
The sum α + β of the contact angle α and the tip angle β of No. 4 is preferably in the range of 160 ° to 180 °, more preferably 1 °
70 ° to 175 °.

Specifically, the conductive blade 3 of this embodiment
No. 4 was made of the same material as that of the blade of Example 1, and each angle was set to α = 110 ° and β = 65 °. With this setting, the distance between the upstream side of the contact portion of the blade 34 and the photosensitive drum 1 can be made longer than in the case of forward contact, and an abnormal image due to abnormal discharge on the upstream side can be removed. It is effective by preventing it.

Embodiment 3 FIG. 4 is a sectional view showing a recording material suction portion in still another embodiment of the image forming apparatus of the present invention. A contact-type adsorption / charging means 40 is provided in the recording material adsorption section. The adsorption / charging means 40 is a conductive type having a thickness direction in a plane parallel to the moving direction of the transfer drum 8 as an adsorption / charging member on the electrode 42. The conductive blade 44 is inclined from the upstream side to the downstream side in the moving direction of the transfer drum 8 and extends toward the transfer drum 8, and the conductive blade 44 is attached to the transfer drum 8. Suction roller 4 serving as a grounding member
6. A regulating member 47 for regulating the transfer electric field on the upstream side is provided on the upstream side surface of the blade 44. The suction roller 46 can be grounded via a resistor 48 as shown in FIG.

The conductive blade 44 has a corner on the upstream side of the tip, that is, the angle of the contact portion (tip angle) has an angle α, and is formed with respect to the tangent at the contact portion of the suction roller 46. The angle (contact angle) has an angle β. By preventing excessive discharge on the upstream side of the contact portion of the conductive blade 44,
The sum α + β of the contact angle α and the tip angle β of the conductive blade 44 is preferably large in order to improve the suction force of the recording material and prevent the suction force from decreasing in a high humidity environment. This was set so as to be 160 ° or more and 180 ° or less. In this embodiment, the contact angle α = 45 ° and the tip angle β =
130 °.

FIG. 6 shows the case where the conductive blade of the third embodiment and the conventional conductive blade were used at an air temperature of 30 ° C.
4 shows a curve of a change in a recording material attraction force with respect to an attraction current in a high humidity environment at a humidity of 80%. 80g / m of recording material immediately after opening
² paper was used.

As shown in FIG. 6, when the conductive blade of this embodiment is used, the attraction force is improved, and a large attraction force can be obtained for the same attraction current.

The method of measuring the recording material attraction force performed in the present invention will be described with reference to FIG. 7. First, a copying operation is started, and the recording material P is attracted to the transfer drum 8 by the attracting portion, and the recording material P is attracted. The copying operation is stopped when the entirety has been attracted to the transfer drum 8. As the recording material P, either A4 size or A3 size paper may be used, but the length in the thrust direction is 297 mm. Recording material P
The remaining portion of the recording material P is peeled off from the transfer drum 8 while leaving a portion 70 mm from the front end of the recording material P adsorbed on the transfer drum 8. And a force gauge (SHIMPO Hand-Held DIGITA
L FORCE GAUGE) 112 is fixed to the portion where the recording material P is peeled off with an adhesive tape, and the 70 mm portion at the tip is transferred to the transfer drum 8.
The recording material P in a state where the recording material P is attracted to the transfer drum 8 is pulled in a tangential direction of the transfer drum 8 and peeled off.

As described above, three embodiments of the present invention have been described. In each case, the toner image formed on the photosensitive drum 1 is transferred to the recording material 6.
This is an image forming apparatus of a type in which an image is directly transferred onto an image to obtain an image, but the present invention is not limited to this.

That is, a belt or the like that rotates while being in contact with the photosensitive drum, which is the first image carrier,
, The toner image formed on the first image carrier is transferred onto the second image carrier, and then the toner image is transferred from the second image carrier onto a recording material. In the above-described image forming apparatus, the toner image on the first image carrier is transferred onto the second image carrier by the transfer member that comes into contact with the first image carrier via the second image carrier. When transferring,
The invention is equally applicable.

[0048]

As described above, according to the present invention,
Since the total amount α + β of the contact angle α of the tip of the charging member of the contact-type charging means extending and contacting the member to be charged and the tip angle β of the contacting corner is specified to be 160 ° or more and 180 ° or less. In the transfer, it is possible to prevent image defects due to excessive discharge on the upstream side of the contact portion, and to improve the transfer efficiency, and to increase the suction force in the suction of the recording material,
It is possible to prevent a decrease in the attraction force in a high humidity environment and to perform the attraction process of the thick paper only once, thereby shortening the image output time.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an image transfer unit in an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a graph showing a change in image density with respect to a transfer current when a conductive blade of a contact-type transfer charging unit and a conventional conductive blade installed in an image transfer unit of FIG. 1 are used.

FIG. 3 is a cross-sectional view illustrating an image transfer unit according to another embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a recording material suction unit according to still another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a state where a suction roller of a ground member serving as a counter electrode is installed via a resistor with respect to a conductive blade of a contact-type suction charging unit installed in the recording material suction unit of FIG.

FIG. 6 is a graph showing a change in attraction force of a recording material with respect to an attraction current when a conductive blade of a contact-type attraction / charging unit and a conventional conductive blade installed in a recording material attraction section of FIG. 3 are used.

FIG. 7 is an explanatory diagram showing a method for measuring the attraction force of a recording material used in the present invention.

FIG. 8 is a schematic configuration diagram illustrating a conventional image forming apparatus.

FIG. 9 is a cross-sectional view illustrating a conductive blade of a contact-type transfer charging unit installed in an image transfer unit of the image forming apparatus of FIG. 8;

FIG. 10 is a cross-sectional view showing a corotron charger of a non-contact type transfer charging unit which may be provided in the image transfer unit of FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photosensitive drum 8 transfer drum 30 contact transfer charging means 34 conductive blade 37 lubricating layer 40 contact suction charging means 44 conductive blade 46 suction roller 48 resistance

Claims (7)

[Claims] 1. An image carrier on which a toner image is formed, a recording material carrier that carries a recording material and conveys it to the image carrier, moves while abutting on the image carrier, and the recording material carrier And a charging member having a conductive substrate that is in contact with the recording material carrier. The conductive substrate has a plate-like shape having a thickness direction in a plane parallel to a moving direction of the recording material carrier. In the image forming apparatus extending in the direction of the recording material carrier and contacting the same, the conductive substrate has a contact angle α between the tangent line of the recording material carrier at the contact portion with the conductive substrate and the conductive substrate. An image forming apparatus wherein a sum α + β of a tip angle β of a contact portion of the conductive substrate with the recording material carrier is 160 ° or more and 180 ° or less. 2. The recording member according to claim 1, wherein the charging member has a conductive substrate in contact with the image carrier via the recording material carrier, and the toner image formed on the image carrier is carried on the recording material carrier. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a transfer charging member for transferring the image onto a material. 3. The image forming apparatus according to claim 1, wherein the charging member is a suction charging member in which a conductive base is in contact with a grounding member via a recording material carrier to adsorb the recording material to the recording material carrier. . 4. The image forming apparatus according to claim 3, wherein said grounding member is grounded via a resistor. 5. The image forming apparatus according to claim 1, wherein a lubricating layer is provided on at least a contact portion side of said conductive substrate. 6. A first image carrier on which a toner image is formed, and a second image carrier on which a toner image is transferred from the first image carrier and which moves while being in contact with the image carrier. , First
Transferring the toner image on the image carrier to the second image carrier,
A charging member having a conductive substrate that is in contact with the first image carrier via the second image carrier, wherein the conductive substrate has a thickness direction in a plane parallel to a moving direction of the recording material carrier. And the plate-shaped conductive substrate has a second shape.
In the image forming apparatus extending in the direction of the image carrier and contacting the first image carrier via the second image carrier, a tangent line at a contact portion between the first image carrier and the conductive substrate is provided. The sum α + β of the contact angle α between the conductive base and the tip angle β of the corner of the conductive base in contact with the first image carrier is 160
An image forming apparatus characterized by being at least 180 degrees and not more than 180 degrees. 7. The image forming apparatus according to claim 6, wherein a lubricating layer is provided on at least a portion of the conductive substrate that is in contact with the first image carrier.