JP2002132034A - Developing device, process cartridge and image forming device - Google Patents

Abstract

(57) [Summary] [Purpose] Reduction in the number of parts and associated cost reduction,
Provided is a developing device capable of improving reliability and assemblability. [Structure] Light transmission window 1 for detecting remaining amount of developer by light detection method
In the developing device having the light transmitting windows 14a and 14b, the light transmitting windows 14a and 14b have rib-shaped light guides (ribs) 14aL.
1 to 14L3, 14bL1 to 14bL3 are integrally erected, and these rib-shaped light guides 14aL1 to 14L
The tip surfaces of 3, 14bL1 to 14bL3 are sloped so that light is totally reflected. According to the present invention, the light transmission windows 14a,
14b is a rib-shaped light guide 14aL1 to 14L3, 1
Since the 4bL1 to 14bL3 are integrally erected, the light guide conventionally required becomes unnecessary, and the number of components can be reduced, the cost can be reduced, and the reliability and the assemblability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device, a process cartridge having the same, and an image forming apparatus. Here, the image forming apparatus forms an image on a recording medium using an electrophotographic image forming method, and includes, for example, an electrophotographic copying machine, an electrophotographic printer (laser beam printer, LED printer, etc.), a facsimile machine, and the like. , A word processor, and the like.

A process cartridge is a unit in which a charging unit, a cleaning unit, a photosensitive drum and a developing device are integrated, and is attached to and detached from an image forming apparatus main body.

[0003]

2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic image forming process, a photosensitive drum and a process means acting on the photosensitive drum are integrated into a process cartridge. A cartridge system is adopted. According to this cartridge system, maintenance of the apparatus can be performed by the user himself without relying on a service person, so that operability can be significantly improved. For this reason, this cartridge system is widely used in image forming apparatuses.

By the way, regarding the replacement of the process cartridge, when the developer (toner) is reduced, the user is notified of the absence of the toner, thereby notifying the life of the process cartridge and prompting the replacement of the process cartridge.

FIG. 14 is a longitudinal sectional view of a laser beam printer 100 as an embodiment of an image forming apparatus for forming an image by an electrophotographic method.

A laser beam printer 10 shown in FIG.
At 0, reference numeral 101 denotes a photosensitive drum which is an electrophotographic photosensitive member which rotates at a constant speed, and the surface of the photosensitive drum 101 is uniformly charged by a charging means 102. Then, a latent image is formed on the photosensitive drum 101 by irradiating the photosensitive drum 101 with a laser beam corresponding to the image information from the exposing unit 103.
The image is developed as a toner image by developing the toner image with a toner image 04.

[0007] Thereafter, the toner image formed on the photosensitive drum 101 is transferred from the paper supply unit to the recording medium P conveyed by the conveying means 105 by the transfer means 106, and the recording medium P on which the toner image has been transferred is fixed by the fixing means. The recording medium P on which the toner image has been fixed is conveyed to the recording medium P, and is discharged outside the apparatus. The transfer residual toner remaining on the photosensitive drum 101 after the transfer of the toner image is scraped off by the cleaning blade 108 and stored in the cleaning container 109. Further, a developing roller 110 that carries toner is disposed in the developing device 104, and a supply roller 111 is rubbed against the developing roller 110, and the toner that has not contributed to the development is scraped off so that fresh toner is always obtained. It is configured to supply toner.

Here, a conventional light transmission type toner remaining amount detecting method will be described. In a developer container 116 for storing the toner T, a first stirring member 112 close to the developing roller 110 and a farther side are arranged. Is provided, and the toner T is conveyed to the supply roller 111 by the rotation of the respective stirring members 112 and 113. Then, as the consumption of the toner T proceeds, the toner T disappears in the rotation area of the second stirring member 113, and the toner T remains only in the area of the supply roller 111 and the rotation area of the first stirring member 112. Become.

The first agitating member 112 comes into contact with the light transmitting windows 114a and 114b attached to the developer container 116 containing the toner T each time it rotates, and the first stirring member 112 is provided inside the windows 114a and 114b. The attached toner T is wiped off. Then, the toner T is consumed and the toner T disappears in the rotation area of the second stirring member 113 as described above, and the area of the supply roller 111 and the first stirring member 11
When the state in which the toner T remains only in the rotation region 2 is such that light is transmitted from the light transmission window 114a to the light transmission window 114b, and the remaining amount of the toner T can be detected.

Here, a light transmission system is shown in FIG.
As shown in the figure, the detection light L is emitted from the light emitting section 115a attached to the image forming apparatus 100, and the detection light L
Is transmitted through the light guide 113a and totally reflected, and then transmitted through the light transmission windows 114a and 114b to be transmitted through the light guide 11a.
3b, the light is totally reflected, and is received by the light receiving unit 115b attached to the image forming apparatus 100.

The main body of the image forming apparatus includes a stirring member 10.
While the time during which the light receiving unit 115b receives the detection light L during one rotation of No. 6 is monitored, the time for receiving the detection light L increases when the amount of the toner T in the developer container 116 decreases. When the specific light receiving time is detected, the user is notified that the toner T is almost exhausted in the developer container 116.

[0012]

However, in the above-mentioned conventional configuration, two parts, that is, the light guides 113a and 113b and the light transmission windows 114a and 114b are required.
It is necessary to provide a position reference for each, and it is difficult to ensure high position accuracy. Also, since the number of parts increases, parts management and extra costs are required.

Accordingly, it is an object of the present invention to provide a developing device, a process cartridge, and an image forming apparatus capable of reducing the number of parts, thereby reducing costs, and improving reliability and assemblability. It is in.

In the cartridge assembling step, in a cartridge having a light transmitting window on the side of a toner injection port for injecting toner into the developing container, the side surface of the light transmitting window is formed at right angles to the toner inflow direction. Then, when the toner is injected, the toner hits the side surface of the light transmission window and does not flow smoothly, resulting in turbulent flow, and the time required for the toner injection is lengthened, resulting in inefficient productivity.

Accordingly, it is an object of the present invention to provide a developing device, a process cartridge, and an image forming apparatus capable of shortening the time required for toner injection and improving productivity.

[0016]

According to a first aspect of the present invention, there is provided a developing apparatus having a light transmission window for detecting a remaining amount of a developer in a light detection system, wherein the light transmission window has a rib. Are formed integrally, and the end surface of the rib is formed as a slope so that light is totally reflected.

According to a second aspect of the present invention, in the first aspect of the present invention, at least one portion of the rib is provided with a bent portion bent in a direction in which light is collected.

According to a third aspect of the present invention, in the first or second aspect, a plurality of the ribs are provided at substantially parallel positions, and each of the ribs has a surface capable of total reflection and a surface capable of entering and exiting. It is characterized by having.

According to a fourth aspect of the present invention, there is provided a developing apparatus having a light transmitting window for detecting a remaining amount of a developer in a light detecting system, wherein the light transmitting window is formed as an integrally molded product, and a cover is provided on the light transmitting window. It is characterized by having a reflection surface of a shape.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the light transmitting window is provided near a developer injection port of a developer container for storing the developer, and the light transmitting window is provided with the developer. The surface on the injection port side is formed so as to open toward the developer injection port.

According to a sixth aspect of the present invention, in the invention of the fourth, fifth or sixth aspect, the inclined surface of the light transmitting window on the side of the developer injection port and the lid-like surface are arranged substantially in parallel. Features.

According to a seventh aspect of the present invention, there is provided a process cartridge including an electrophotographic photosensitive member, and a developing unit and a cleaning unit acting on the electrophotographic photosensitive member, wherein the developing unit is provided with the developing unit. It is characterized by comprising.

According to an eighth aspect of the present invention, there is provided a process cartridge comprising an electrophotographic photosensitive member and a developing unit and a cleaning unit acting on the electrophotographic photosensitive member, wherein the developing unit is provided with the developing unit according to the fourth, fifth or sixth aspect. It is characterized by comprising.

According to a ninth aspect of the present invention, there is provided an image forming apparatus comprising an electrophotographic photoreceptor and a charging unit, a developing unit, a transfer unit and a cleaning unit acting on the electrophotographic photoreceptor. A developing device according to item 2 or 3.

According to a tenth aspect of the present invention, there is provided an image forming apparatus including an electrophotographic photosensitive member and a charging unit, a developing unit, a transfer unit and a cleaning unit acting on the electrophotographic photosensitive member. A developing device according to the fifth or sixth aspect.

[0026]

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

<Embodiment 1> FIG. 1 is a longitudinal sectional view showing a schematic configuration of an entire image forming apparatus according to the present invention, and FIG. 2 is a sectional view of a process cartridge according to the present invention (cross section taken along line ZZ in FIG. 4). Figure).

First, the overall structure of an image forming apparatus A according to the present invention will be described with reference to FIG.

The image forming apparatus A shown in FIG. 1 includes a drum type electrophotographic photosensitive member (hereinafter, referred to as a photosensitive drum) 1 as a first image carrier, and the photosensitive drum 1 is driven by a drive (not shown). It is driven to rotate in the direction shown by the arrow (clockwise) by means. Around the photosensitive drum 1, a charging device 2 for uniformly charging the surface of the photosensitive drum 1, and an exposure device 3 for irradiating a laser beam based on image information to form an electrostatic latent image on the photosensitive drum 1 A developing device 4 for attaching toner to the electrostatic latent image to develop the electrostatic latent image as a toner image, a transfer device 6 for transferring the toner image on the photosensitive drum 1 onto the recording material S, and after the toner image is transferred. Cleaning blade 8 for removing transfer residual toner remaining on the surface of photosensitive drum 1
And so on.

Here, the photosensitive drum 1, the charging device 2, the cleaning blade 8 and the developing device 4 are integrated into a cartridge to constitute a process cartridge B.
The process cartridge B is removably mounted on the image forming apparatus A.

In addition, the image forming apparatus A feeds the recording medium S toward the transfer device 6 and conveys the recording medium S. The toner image is transferred to the recording medium S on which the toner image has been transferred. Is provided.

Hereinafter, the photosensitive drum 1 will be described in detail.

The photosensitive drum 1 is formed by applying an organic photoconductor layer (OPC photosensitive member) to the outer peripheral surface of an aluminum cylinder. The photosensitive drum 1 is rotatably supported at both ends by supporting members. The driving force from a driving motor (not shown) is transmitted to one end, and the one end is driven to rotate in the direction indicated by the arrow.

As the charging device 2, a contact charging type (see JP-A-63-149669) can be used. The charging device 2 is constituted by a conductive roller formed in a roller shape. The conductive roller 2 is brought into contact with the surface of the photosensitive drum 1, and the charging bias is applied to the conductive roller 2 by a power supply (not shown). By applying a voltage, the surface of the photosensitive drum 1 is uniformly charged.

The exposure device 3 has a polygon mirror (not shown), and the polygon mirror is irradiated with image light corresponding to an image signal by a laser diode (not shown).
The polygon mirror is driven to rotate at a high speed by a scanner motor (not shown), and selectively exposes the surface of the charged photosensitive drum 1 with the reflected image light via an imaging lens (not shown), a reflection mirror 3a, and the like. The photosensitive drum 1
An electrostatic latent image is formed thereon.

In the developing device 4, the developing roller 10 is positioned and arranged so as to face the photosensitive drum 1 with a small gap (about 300 μm), and is exposed by the toner T supplied by the developing roller 10. The electrostatic latent image on the drum 1 is developed. This development is performed as follows.

That is, the toner T in the developing container 16 is sent to the supply roller 11 by the stirring member 12, and the outer periphery of the development roller 10 is coated with a thin layer of toner T by the rotating supply roller 11 and the toner regulating blade 10a.
An electric charge is applied to the toner T (frictional charging). Then, by applying a developing bias between the developing roller 10 and the photosensitive drum 1 on which the electrostatic latent image is formed, the toner T is attached to the electrostatic latent image to develop the electrostatic latent image as a toner image.

The transfer device 6 transfers the toner image formed on the photosensitive drum 1 to the recording medium S.

After the toner image formed on the photosensitive drum 1 by the developing device 4 is transferred to the recording medium S by the transfer device 6, the cleaning blade 8 remains on the surface of the photosensitive drum 1 without being transferred to the recording medium S. The transfer residual toner is removed. The transfer residual toner scraped off by the cleaning blade 8 is transferred to the cleaning container 9.
Is accumulated inside.

The feeding device 5 feeds the recording medium S to the image forming section, and is driven in accordance with the image forming operation to separate and feed the recording medium S one by one.

The fixing device 7 fixes the toner image transferred to the recording medium S, and the recording medium S on which the toner image has been fixed is discharged to the outside by a discharge device (not shown).

Next, a method for detecting the remaining amount of light transmitting toner will be described with reference to FIG. FIG. 3 is a view for explaining the optical axis of the total reflection rib integrated light transmission window.

A stirring member 12 is provided in a developer container 16 for storing the toner T. The rotation of the stirring member 12 causes the toner T to be transported to the supply roller 11.

By the way, the stirring member 12 rotates and rubs the light transmitting windows 14a, 14b attached to the developer container 16 for storing the toner T, and these light transmitting windows 14a, 1b are rubbed.
4b, the toner T adhered to the inner surface is wiped off and cleaned.

When the remaining amount of the toner T in the developer container 16 decreases, the light transmitting window 14a is moved to the light transmitting window 14a.
Light is transmitted to b, and the remaining amount of the toner T can be detected.

When the detection light L is emitted from the light emitting element 15a attached to the image forming apparatus A, the detection light L passes through the light transmitting windows 14a and 14b and is attached to the image forming apparatus main body A. The received light is received by the light receiving element 15b.
Then, the detection time of the detection light L is monitored. When the amount of the toner T in the developer container 16 decreases, the time for receiving the detection light L increases. The user can be notified that the toner T is almost exhausted in the developer container 16.

"Rib-shaped light guide" Next, a rib-shaped light guide will be described with reference to FIGS. 4 is a partial plan view of the process cartridge, FIG. 5 is a detailed view of the rib-shaped light guide, FIG. 6 is a partial cross-sectional view in the longitudinal direction of the process cartridge, and FIG. 7 is a detailed view of the rib-shaped light guide.

Rib-shaped light guides 14aL1, 14aL
2, 14aL3 and 14bL1, 14bL2, 14bL3
Are formed integrally with the light transmission windows 14a and 14b.

As shown in FIG. 6, the detection light L emitted from the light emitting element 15a is supplied to the rib-shaped light guides 14bL1 to 14bL1.
The light is radiated on a 4bL3 45 ° inclined total reflection surface.
The detection light L emitted from the light emitting element 15a is a diffused light, and if it is totally reflected as it is, the signal intensity is further reduced.
Therefore, as shown in FIG.
Centering on the angle θ2 formed by the 4bL2 total reflection surface and the optical axis L,
The angle θ2, the angle θ1 between the total reflection surface of the rib-shaped light guide 14bL1 and the optical axis L, and the angle
The relationship of θ1 <θ2 <θ3 is established between the total reflection surface bL3 and the angle θ3 formed by the optical axis L so that the detection light L does not diverge.

FIG. 4 is a partial plan view of the process cartridge B, showing a state in which light is focused on the light receiving element 15b. Although not shown, the light emitting element 15a
Light from the light source is collected in a similar configuration.

FIG. 5 shows a rib-shaped light guide 14bL1 (1
It is a detailed explanatory view of 4aL1) to 14bL3 (14aL3).

The rib-shaped light guides 14bL1 (14aL1) to 1b are provided so that the detection light L can be collected without diverging.
Total reflection surface 14bL1 at the center of 4bL3 (14aL3)
b, 14bL2b, 14bL3b (14aL1b, 14
aL2b, 14aL3b) and the total reflection surface 14b on the opposite end side.
L1a, 14bL2a, 14bL3a (14aL1a,
14aL2a, 14aL3a) and 14bL1c, 14b
L2c, 14bL3c (14aL1c, 14aL2c,
14aL3c) is bent toward the light receiving element 15b (light emitting element 15a). With this configuration, the detection light L emitted from the light emitting element 15a
Thus, a stable toner detection signal can be obtained by suppressing the attenuation of the detection light L incident on the light receiving element 15b.

As described above, in the present embodiment, the rib-shaped light guides 14aL1 to 14aL are provided on the light transmitting windows 14a and 14b.
L3, 14bL1 to 14bL3 are integrally erected, and these rib-shaped light guides 14aL1 to 14L3, 14bL
Since the tip surface of 1 to 14bL3 is inclined so that light is totally reflected, a conventionally required light guide is not required, thereby reducing the number of parts, resulting in cost reduction, and improving reliability and assemblability. Can be.

Second Embodiment Next, a second embodiment of the present invention will be described. Note that the basic configuration of the image forming apparatus according to the present embodiment is the same as that of the first embodiment, and therefore illustration and description thereof are omitted.

"Toner Injection Port" FIG. 8 is a cross-sectional view of the process cartridge according to the present invention, and FIG. 9 is a view of the process cartridge with the toner cap removed from the toner injection port side. Is the toner cap 3
0 extends to the toner injection port 31 from which it has been removed.

As shown in FIG. 8, the light transmitting windows 14a, 14a
In b, guide surfaces 14a2 and 14b2 for guiding toner toward the toner inlet 31 are formed at an angle of approximately 45 degrees, and reflectors 14a1 and 14b1 are formed.

Thus, as described above, the light transmission windows 14a, 1
4b, the guide surfaces 14a2 and 14b2 for guiding the toner toward the toner inlet 31 are formed at an angle of approximately 45 °, so that even if the light transmitting windows 14a and 14b protrude in the direction of the toner inlet 31, No turbulence occurs during the injection, and the time required for the toner injection is reduced, and the assembly productivity is improved.

[Light Detection Method] Next, a method of detecting the remaining amount of light transmitting toner will be described with reference to FIGS. FIG.
0 is a side sectional view of the process cartridge, FIG. 11 is a partial plan view of the process cartridge, and FIG. 12 is a diagram illustrating an optical axis of a light transmitting window integrated with a reflector.

As shown in FIG. 10, a first stirring member 12 and a second stirring member 13 near the developing roller 10 are provided in a developer container 16 containing the toner T.
As the stirring members 12 and 13 rotate, the toner T is transported to the supply roller 11. Then, as the consumption of the toner T progresses, the toner T disappears in the rotation area of the second stirring member 13 and the area of the supply roller 11
The toner T remains only in the rotation region of the stirring member 12.

Each time the first stirring member 12 rotates, it comes into contact with the light transmitting windows 14a, 14b attached to the developer container 16 containing the toner T, and the first stirring member 12 is placed inside the windows 14a, 14b. The attached toner T is wiped off. Then, the toner T is consumed and the toner T is lost in the rotation area of the second stirring member 13 as described above, and the toner T remains only in the area of the supply roller 11 and the rotation area of the first stirring member 12. Then, light is transmitted from the light transmitting window 14a to the light transmitting window 14b, and the remaining amount of the toner T can be detected.

In the light transmission method shown in FIGS. 8, 11 and 12, the detection light L is emitted from the light emitting portion 15a attached to the image forming apparatus main body A, and the detection light L is reflected from the light transmission window 14a. The light transmission window 14 after being reflected by the plate 14a1
The light passes through the light transmitting window 14a while changing its course in the direction b, passes through the light transmitting window 14b, is reflected by the reflection plate 14b1, and is received by the light receiving unit 15b attached to the image forming apparatus main body A.

The light transmitting windows 14a and 14b are provided with a reflecting plate 14a.
1, 14b1, and these reflectors 14a1,
14b1 has the same surface roughness as the light transmitting portions of the light transmitting windows 14a and 14b. The light transmitting surface tends to specularly reflect when tilted to around 45 °, and the present invention utilizes this property. Also, as shown in detail in FIG.
“b” is an integrally molded product made of PS or the like, and the direction in which the mold is removed is the direction of 14b1, 14b2.

As described above, by forming the lid-like reflecting plates 14a1 and 14b1 integrally with the light transmitting windows 14a and 14b, the reflecting plates 14a1 and 14b1 can be easily formed with the same degree of roughness as the light transmitting windows 14a and 14b. 14b1 can be realized. Then, the light transmitting windows 14a and 14b are connected to the reflecting plate 14a.
The positioning accuracy between the light emitting unit 15a and the light receiving unit 15b can be improved by directly providing the light receiving units 1 and 14b1.

By monitoring how long the detection light L has been received, when the amount of the toner T in the developer container 16 decreases, the time for receiving the detection light L increases.
When a specific light receiving time is detected, it is possible to notify the user that the developer container 16 is running out of toner.

[0065]

As is apparent from the above description, according to the present invention, the rib is integrally provided on the light transmitting window, and the tip end surface of the rib is formed as a slope so that the light is totally reflected. The light guide, which has been required, is no longer necessary, and the effects of reducing the number of components, resulting in cost reduction, and improving reliability and assemblability can be obtained.

Further, according to the present invention, the light transmission window is formed of an integrally molded product, and the light transmission window is provided with a lid-like reflection surface, so that the time required for toner injection is reduced and productivity is improved. The effect that can be obtained is obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating a schematic configuration of an entire image forming apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a cross-sectional view (a cross-sectional view taken along the line ZZ in FIG. 4) of the process cartridge according to the first embodiment of the present invention.

FIG. 3 is a diagram for explaining an optical axis of the total reflection rib integrated light transmission window according to the first embodiment of the present invention.

FIG. 4 is a partial plan view of the process cartridge according to Embodiment 1 of the present invention.

FIG. 5 is a detailed view of a rib-shaped light guide according to the first embodiment of the present invention.

FIG. 6 is a partial longitudinal sectional view of the process cartridge according to Embodiment 1 of the present invention.

FIG. 7 is a detailed view of the rib-shaped light guide according to the first embodiment of the present invention.

FIG. 8 is a sectional view of a process cartridge according to a second embodiment of the present invention.

FIG. 9 is a view of the process cartridge according to Embodiment 2 of the present invention as viewed from a toner injection port side.

FIG. 10 is a side sectional view of a process cartridge according to Embodiment 2 of the present invention.

FIG. 11 is a partial plan view of a process cartridge according to Embodiment 2 of the present invention.

FIG. 12 is a diagram illustrating an optical axis of a light-transmitting window integrated with a reflector according to a second embodiment of the present invention.

FIG. 13 is an enlarged detailed sectional view of a reflector-integrated light transmitting window according to Embodiment 2 of the present invention.

FIG. 14 is a longitudinal sectional view illustrating a schematic configuration of an entire conventional image forming apparatus.

FIG. 15 is a partial side sectional view showing a conventional toner remaining amount detecting method.

[Explanation of symbols]

Reference Signs List 1 photosensitive drum (electrophotographic photosensitive member) 2 charging device (charging means) 4 developing device (developing device) 6 transfer device (transfer device) 8 cleaning blade (cleaning device) 14a, 14b light transmitting window 15a light emitting portion 15b light receiving portion 16 Developer container A Image forming device B Process cartridge L Detection light

Claims (10)

[Claims] 1. A developing device having a light transmission window for detecting a remaining amount of a developer in a light detection system, wherein a rib is integrally provided upright on the light transmission window so that light is totally reflected at a tip end surface of the rib. A developing device characterized by having a slope. 2. The developing device according to claim 1, wherein at least one of the ribs has a bent portion bent in a direction in which light is collected. 3. The method according to claim 1, wherein a plurality of the ribs are provided at substantially parallel positions, and each of the ribs has a surface capable of total reflection and a surface capable of entering and exiting on opposite surfaces. Developing device. 4. A developing device having a light-transmitting window for detecting a remaining amount of a developer in a light-detecting method, wherein the light-transmitting window is formed as an integrally molded product, and a lid-like reflecting surface is provided on the light-transmitting window. A developing device. 5. The light-transmitting window is provided near a developer inlet of a developer container for storing a developer, and the light-transmitting window is opened with its surface on the side of the developer inlet facing the developer inlet. The developing device according to claim 4, wherein the developing device is formed as described above. 6. The developing device according to claim 4, wherein an inclined surface of the light transmitting window on a developer injection port side and a lid-like surface are arranged substantially in parallel. 7. A process cartridge comprising an electrophotographic photoreceptor, a developing means acting on the electrophotographic photoreceptor, and a cleaning means, wherein the developing means is constituted by the developing device according to claim 1, 2 or 3. And process cartridge. 8. A process cartridge comprising an electrophotographic photoreceptor, a developing means acting on the electrophotographic photoreceptor, and a cleaning means, wherein the developing means is constituted by the developing device according to claim 4, 5 or 6. And process cartridge. 9. An image forming apparatus comprising an electrophotographic photoreceptor and a charging unit, a developing unit, a transfer unit and a cleaning unit acting on the electrophotographic photoreceptor, wherein the developing unit is a developing device according to claim 1, 2, or 3. An image forming apparatus comprising: an image forming apparatus. 10. An image forming apparatus comprising an electrophotographic photoreceptor and a charging unit, a developing unit, a transfer unit and a cleaning unit acting on the electrophotographic photoreceptor, wherein the developing unit is a developing unit according to claim 4, 5 or 6. An image forming apparatus comprising: an image forming apparatus.