JPH11258907A - Developing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device and an image forming device where miniaturization is attained, and strength and accuracy of a developing casing are enhanced and also the occurrence of voltage leakage at the developing casing is prevented. SOLUTION: These devices have a metallic developing casing 40 arranged opposed to photoreceptive drums 1a-1d carrying an electrostatic latent image and storing developer, a magnet roller 41 provided inside the metallic developing casing 4 and forming a developer image by supplying the developer to the electrostatic latent image on the photoreceptor drums 1a-1d, bias apply means 45 and 46 applying bias to the photoreceptor drums 1a-1d and the magnet roller 41, and an insulated resin layer 51 covered with the parts A-D of the developing casing 40 proximate to at least either of the photoreceptor drums 1a-1d and the magnet roller 41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device and an image forming apparatus provided in, for example, a color electrophotographic apparatus.

[0002]

2. Description of the Related Art In a color electrophotographic apparatus, image forming units are horizontally arranged for four colors.
Normally, an image is formed for each color component corresponding to four types of image data obtained by color separation for each color component of yellow, magenta, cyan and black.

An image of each color formed by the image forming unit is successively transferred onto a transfer material conveyed by a transfer material conveying mechanism below the image forming unit, and then fixed by a fixing device to be discharged. Is done.

The image forming unit is provided with a photoreceptor rotatably, and a charger, an exposing unit, a developing unit, a transfer unit, a cleaning unit, and a charge removing unit are sequentially provided around the photoreceptor along the rotation direction. Is arranged.

[0005] The developing section has a developing casing. Inside the developing casing, a magnetic toner and a carrier are provided.
A component developer is contained. Further, a transport screw for stirring and transporting the magnetic toner and the carrier is provided in the developing casing, and a magnet roller for supplying the two-component developer transported by the transport screw to the photoconductor is rotatably provided. ing.

In order to reduce the size of a color electrophotographic apparatus, it is important to reduce the size of an image forming unit. However, the bottleneck of this miniaturization is the performance of the photoreceptor, and in consideration of this, when trying to increase the process speed in order to copy a large number of sheets, the distance between the exposure unit and the development unit is reduced. It becomes stricter, and there is naturally a limit in consideration of the transfer material transporting portion.

[0007] For example, the exposure section and the development section are 0.15 sec.
Therefore, there is a limit to the diameter of the photoreceptor, and in order to reduce the size of the apparatus, it is effective to reduce the size of the photoreceptor in the left-right direction, and to reduce the size of the developing unit and the cleaning unit.

[0008]

However, in practice, the frequency of use of these color image forming units is not uniform, so it is necessary that the image forming units of each color have a structure that can be replaced, adjusted, and maintained independently. In order to do so, a gap is required between the image forming units, and there is a limit to miniaturization.

Further, since the developing casing of the developing section is formed of a synthetic resin material such as polycarbonate,
It was designed with a minimum thickness of 2 mm and was large. Further, when the developing casing is formed of a synthetic resin material, there is a drawback that rigidity is insufficient, a downward bending due to the weight of the developer or the like, uneven image density, and an increase in driving torque of the developing unit.

Further, since the gap between the developing casing and the conveying screw is only 1 mm, when the developing casing is formed of a synthetic resin material, accuracy is not obtained, and the conveying screw and the developing casing are in contact with each other. For this reason, there is also an inconvenience that a large stress is applied to the developer and image density unevenness occurs.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a developing device and an image forming apparatus capable of reducing the size, improving the strength and accuracy of a developing casing, and preventing the occurrence of voltage leakage in the developing casing.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a metal developing device which is opposed to an image carrier for carrying an electrostatic latent image and contains a developer. A casing, a developer supply unit provided in the development casing, for supplying a developer to the electrostatic latent image on the image carrier to form a developer image, the image carrier, and the developer supply unit Bias applying means for applying a bias to the image bearing member, and an insulating coating layer coated on a portion of the developing casing adjacent to at least one of the image carrier and the developer supplying means.

According to a second aspect of the present invention, there is provided a metal developing casing opposed to an image carrier for carrying an electrostatic latent image and containing a two-component developer comprising a toner and a carrier, and provided in the developing casing. A stirring and conveying means for stirring and conveying the two-component developer, and a two-component developer provided in the developing casing and stirred and conveyed by the stirring and conveying means to supply the electrostatic latent image on the image carrier. A developer supply unit that forms a developer image by applying a bias to the image carrier and the developer supply unit; and a bias application unit that is close to at least one of the image carrier and the developer supply unit. An insulating coating layer coated on a portion of the developing casing.

According to a third aspect of the present invention, there is provided a metal developing casing which is opposed to an image carrier for carrying an electrostatic latent image and accommodates a developer, and which is provided in the developing casing and is provided on the image carrier. Developer supply means for supplying a developer to the electrostatic latent image to form a developer image, bias applying means for applying a bias to the image carrier and the developer supply means, An insulating member forming a portion of the developing casing adjacent to at least one of the developer supply means.

According to a fourth aspect of the present invention, there is provided a metal developing casing which is opposed to an image carrier for carrying an electrostatic latent image and accommodates a two-component developer comprising a toner and a carrier, and is provided in the developing casing. A stirring and conveying means for stirring and conveying the two-component developer, and a two-component developer provided in the developing casing and stirred and conveyed by the stirring and conveying means to supply the electrostatic latent image on the image carrier. A developer supply unit that forms a developer image by applying a bias to the image carrier and the developer supply unit; and a bias application unit that is close to at least one of the image carrier and the developer supply unit. An insulating member forming a part of the developing casing.

According to a fifth aspect of the present invention, there is provided a metal developing casing which is opposed to an image carrier for carrying an electrostatic latent image and accommodates a developer, and which is provided in the developing casing and which is provided on the image carrier. Developer supply means for supplying a developer to the electrostatic latent image to form a developer image, bias applying means for applying a bias to the image carrier and the developer supply means, An insulating member attached to a portion of the developing casing adjacent to at least one of the developer supply means.

According to a sixth aspect of the present invention, there is provided a metal developing casing opposed to an image carrier for carrying an electrostatic latent image and containing a two-component developer comprising a toner and a carrier, and provided in the developing casing. A stirring and conveying means for stirring and conveying the two-component developer, and a two-component developer provided in the developing casing and stirred and conveyed by the stirring and conveying means to supply the electrostatic latent image on the image carrier. A developer supply unit that forms a developer image by applying a bias to the image carrier and the developer supply unit; and a bias application unit that is close to at least one of the image carrier and the developer supply unit. An insulating member attached to a portion of the developing casing.

According to a seventh aspect of the present invention, there are provided a plurality of image carriers which are arranged at predetermined intervals in a conveying direction of a material to be transferred and carry an electrostatic latent image, and each of the image carriers has A plurality of metal developing casings which are opposed to each other and contain developers of different colors are provided in the developing casings, and the developer is supplied to the electrostatic latent image on the image carrier to form a developer image. Developer supply means to be formed, a plurality of transfer means for transferring the developer images formed on the plurality of image carriers to the material to be transferred, and after the transfer of the developer image by the plurality of transfer means, A plurality of removing means for removing the developer remaining on the plurality of image carriers, and a removing means for one color before which is formed integrally with the developing casing and located on the upstream side in the transport direction of the material to be transferred are housed. A metal case portion, and the plurality of image carriers, Voltage applying means for applying a voltage to the developer supplying means and the removing means; and an insulating coating layer which is coated on the portion of the developing casing and the case portion which are close to the image carrier, the developer supplying means and the removing means. And

According to an eighth aspect of the present invention, there are provided a plurality of image carriers which are arranged at predetermined intervals in a conveying direction of a transfer material and carry an electrostatic latent image, and each of the image carriers has an electrostatic latent image. A plurality of metal developing casings which are opposed to each other and contain developers of different colors are provided in the developing casings, and the developer is supplied to the electrostatic latent image on the image carrier to form a developer image. Developer supply means to be formed, a plurality of transfer means for transferring the developer images formed on the plurality of image carriers to the material to be transferred, and after the transfer of the developer image by the plurality of transfer means, A plurality of removing means for removing the developer remaining on the plurality of image carriers, and a removing means for one color before which is formed integrally with the developing casing and located on the upstream side in the transport direction of the material to be transferred are housed. A metal case portion, and the plurality of image carriers, A voltage application unit for applying a voltage to the developer supply unit and the removal unit; and an insulating member forming a part of the developing casing and the case portion close to the image carrier, the developer supply unit, and the removal unit. .

According to a ninth aspect of the present invention, there are provided a plurality of image carriers which are arranged at predetermined intervals in a conveying direction of a material to be transferred and carry an electrostatic latent image, and each of the image carriers has an electrostatic latent image. A plurality of metal developing casings which are opposed to each other and contain developers of different colors are provided in the developing casings, and the developer is supplied to the electrostatic latent image on the image carrier to form a developer image. Developer supply means to be formed, a plurality of transfer means for transferring the developer images formed on the plurality of image carriers to the material to be transferred, and after the transfer of the developer image by the plurality of transfer means, A plurality of removing means for removing the developer remaining on the plurality of image carriers, and a removing means for one color before which is formed integrally with the developing casing and located on the upstream side in the transport direction of the material to be transferred are housed. A metal case portion, and the plurality of image carriers, A voltage applying means for applying a voltage to the developer supply means, and the removing means, and an insulating member attached to a portion of the developing casing and the case portion close to the image carrier, the developer supplying means, and the removing means. Have.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings. FIG. 1 schematically shows an internal configuration of a four-tandem color electronic copying apparatus.

In FIG. 1, reference numeral 10 denotes an apparatus main body. An original placing table 10a is provided on the upper surface of the apparatus main body 10, and the placed originals are automatically fed one by one onto the original placing table 10a. An automatic document feeder (ADF) 11 is provided. The automatic document feeder 11 includes a document table 10a.
Also functions as an upper document holder.

A document scanner unit 12 for exposing the document is provided on the upper side in the apparatus main body 10.
The scanner unit 12 is provided with a plurality of carriages (not shown) so as to be movable. These carriages include an exposure lamp 13 for irradiating the original with light, a first reflecting mirror 14 for reflecting light reflected from the original, The second and third reflecting mirrors 15, which reflect the reflected light of
16. An optical lens 17 and a photoelectric conversion element 18 are provided in the optical path of the light reflected by the third reflection mirror 16.

A laser beam scanning unit 19 that emits a laser beam corresponding to image information is provided in the apparatus main body 10. The laser light emitted from the laser light scanning unit 19 is guided to the image forming section A. The image forming section A has a plurality of image forming units Sa to Sd arranged along the transport direction of a sheet as a transfer material, and a photosensitive drum as an image carrier of the image forming units Sa to Sd. 1a to 1d are respectively guided and irradiated to form an electrostatic latent image.

A transport belt 19 is provided in a substantially horizontal state so as to face the lower side of each of the photosensitive drums 1a to 1d of the image forming units Sa to Sd. Transfer devices 5a to 5d, which constitute a part of the image forming units Sa to Sd, respectively, on opposite sides of the photosensitive drums 1a to 1d via the transport belt 19.
d is arranged.

At the bottom of the apparatus main body 10, a plurality of cassettes 20a and 20b accommodating sheets of different sizes are arranged. Pickup rollers 21a and 21b are in rolling contact with the uppermost sheet P in these cassettes 20a and 20b to form sheet feeders 22a and 22b. Paper feeder 2
A paper transport device 23 is disposed on the paper feed side of 2a, 22b, and transports the paper P supplied from each paper feed device 22a, 22b to a pair of registration rollers 24 disposed on the front side of the transport belt 19. A manual paper feed unit 25 is provided on one side surface of the apparatus main body 10 so as to join in the middle of the paper conveyance device 23 on the front side of the registration roller pair 24.

A fixing device 26 and a feed roller pair 27 are disposed on the carry-out side of the transport belt 19. The fixing device 26 includes a heat roller 29 and a press roller 30 that presses the sheet by pressing the lower portion of the heat roller. A discharge port 31 is provided on the other side of the apparatus main body 10, and a discharge tray 28 is attached to the discharge port 31.

FIG. 2 is an enlarged view showing the image forming units Sa to Sd. Around the photosensitive drums 1a to 1d of the image forming units Sa to Sd, charging devices 2a to 2d for uniformly charging the surfaces of the photosensitive drums 1a to 1d sequentially along the respective rotating directions, and the photosensitive drums Developing devices 4a to 4d for developing latent images formed on 1a to 1d, transfer devices 5a to 5d for transferring developer images formed on photosensitive drums 1a to 1d onto paper P, and removing residual toner Cleaning devices 6a to 6d as a removing means, and static eliminators 7a to 6d for removing residual potential remaining on the photosensitive drums 1a to 1d after the toner is removed by the cleaning device.
7d is provided.

With respect to the transport belt 19 for transporting the paper P, the developing device 4a sequentially arranged from the upstream side to the downstream side contains a yellow developer, and the developing device 4b
Contains a magenta (magenta) developer, a developing device 4c contains a cyan (blue-green) developer, and a developing device 4d contains a black (black) developer. That is, the developing devices 4a to 4d are arranged in the order of the color that is frequently used along the transport direction of the paper P.

The developing devices 4a to 4d include a developing casing 4
0, and a developing magnet roller as a developer supply means for supplying a developer to the photosensitive drums 1a to 1d, facing the photosensitive drums 1a to 1d with a predetermined gap in the developing casing 40. 41 is provided rotatably. On the upper side of the developing magnet roller 41, a blade 43 facing the developing magnet roller 41 with a predetermined gap is provided to regulate the layer thickness of the developer on the developer magnet roller 41. I have. Further, the upper and lower transport augers 42a and 42b, which are a pair of agitating and transporting means, are provided on the developing casing 40 in a vertically rotatable manner.

The cleaning devices 6a to 6d include blades b1 to b4, which are scraping members for scraping off toner remaining on the surfaces of the photosensitive drums 1a to 1d, a case body 62 as a case part, and the inside of the case body 62. And an auger 63 that is rotatably driven to transfer the developer stored in the case body 62 in a predetermined direction.

The case body 62 of the cleaning devices 6a to 6d, in particular, is integrally formed with the lower end of the developing casing 40 constituting the developing devices 4a to 4d.
The developer collecting section 65 is configured by the transport auger 63.

Since the developer collecting section 65 in the cleaning devices 6a to 6d and the developing devices 4a to 4d are configured so as to be back-to-back, the developing devices 4a to 4d of the image forming unit S are opposed to each other. Body drum 1a
1d, and the developer recovery section 65 acts on one of the photosensitive drums 1a to 1d on the upstream side as described later.

FIG. 3 schematically shows the actual configuration of the image forming section A. On the upstream side of the first photosensitive drum 1a, there is arranged a first image forming unit Sa in which the developing device 4a described above and the developer collecting section 65 of the cleaning device on one upstream side are integrated. A second image forming unit S is provided between the first photosensitive drum 1a and the second photosensitive drum 1b.
b, a third image forming unit Sc is arranged between the second photosensitive drum 1b and the third photosensitive drum 1c, and the third photosensitive drum 1c and the fourth photosensitive drum 1d are arranged.
The fourth image forming unit Sd is arranged between the image forming unit and the image forming unit.

The developer collecting section 65 does not function at all because there is no photosensitive drum facing the developer collecting section 65 in the first image forming unit Sa. Therefore,
Unlike the other image forming units Sb to Sd, at least the auger 63 is removed.

Therefore, the first photosensitive drum 1a
The developing device 4a forming the first image forming unit Sa and the developer collecting section 65a of the second image forming unit Sb forming the first cleaning device 6a are arranged to face each other.

Around the photosensitive drum 1a, a charging device 2a, an exposure device 3a, a transfer device 5a,
The blades b1, which are scraping members of the cleaning device 6a, are arranged independently.

For the second photosensitive drum 1b, a developing device 4b forming a second image forming unit Sb and a third image forming unit Sc forming a second cleaning device 6b
Are disposed to face each other.

Around the photosensitive drum 1b, a charging device 2b, an exposure device 3b, a transfer device 5b,
The blades b2, which are scraping members of the cleaning device 6b, are arranged independently.

For the third photosensitive drum 1c, a developing device 4c forming a third image forming unit Sc and a fourth image forming unit Sd forming a second cleaning device 6c
Are disposed opposite to each other.

Around the photosensitive drum 1c, a charging device 2c, an exposure device 3c, a transfer device 5c, a third
The blades b3, which are scraping members of the cleaning device 6c, are arranged independently.

The developing device 4d constituting the fourth image forming unit Sd is disposed so as to face the fourth photosensitive drum 1d. Then, around the photosensitive drum 1d,
A cleaning device 6 including a charging device 2d, an exposure device 3d, a transfer device 5d, a blade b4, and a developer collecting unit 65d.
d are individually arranged.

When an image is formed, the document table 1
A document is placed on the document 0a, and a copy button (not shown) is turned on. As a result, the exposure lamp 13 is turned on, and each carriage travels, and light is scanned on the original. The reflected light reflected from the original by this scanning is received by the photoelectric conversion element 18 via the first to third reflection mirrors 14 to 16 and the optical lens 17 and is photoelectrically converted.

By this photoelectric conversion, a laser beam corresponding to the image information is emitted from the laser beam scanning unit 19, and the laser beam is scanned by a polygon mirror. The laser light to be scanned is guided to each of the photosensitive drums 1a to 1d via an optical system in the unit and is irradiated.

The surfaces of the photosensitive drums 1a to 1d are uniformly charged by the charging devices 2a to 2d, and an electrostatic latent image of a document is formed by irradiating a laser beam. The electrostatic latent images are sent to and opposed to the developing devices 4a to 4d by the rotation of the photosensitive drums 1a to 1d, and color images are formed by supplying toners of the respective colors.

That is, the electrostatic latent image formed on the photosensitive drum 1a is opposed to the developing device 4a, is supplied with the developer and is visualized, and a yellow (yellow) developer image is formed. On the other hand, for example, the sheet P taken out from the cassette 20a of the sheet feeding device 22a is guided from the sheet conveying device 23 to the conveying belt 19 via the pair of registration rollers 24, and is opposed to the transfer device 5a at the surface of the photosensitive drum 1a. Is transferred onto the sheet P.

Further, when the sheet P is conveyed and opposed to the transfer device 5b, the magenta developer image on the surface of the photosensitive drum 1b is transferred to be superimposed on the yellow developer image on the sheet P. When facing the transfer device 5c, the cyan developer image is transferred so as to overlap the developer image already transferred. When facing the transfer device 5d, the black developer image is multiplex-transferred onto the developer image that has already been transferred.

The sheet P on which the developer images of the respective colors are sequentially transferred in a multiplex manner is conveyed to the fixing device 26, and the developer image is fixed on the sheet P to form a color image. Then, the fixed paper P is discharged to the discharge tray 28.

On the other hand, in the photosensitive drums 1a to 1d, the developer remaining on the peripheral surface is
It is scraped off by blades b1 to b4 a to 6d.
The developer scraped off by each of the blades b1 to b4 is received by the opposing developer recovery sections 65a to 65d, collected at a predetermined site by an auger 62 disposed here, and is discarded every time a predetermined amount is reached. Is done.

The potentials remaining on the surfaces of the photosensitive drums 1a to 1d are neutralized by uniform light irradiation by the neutralization devices 7a to 7d. Then, the charging devices 2a to 2d again
Uniformly charges the surfaces of the uncharged photosensitive drums 1a to 1d, and the above operation is repeated.

As described above, in the present invention, the developing device 4a disposed opposite to the photosensitive drums 1a to 1d
To 4d, and the first to fourth image forming units Sa to Sd in which the developer collecting sections 65 to 65c constituting the cleaning devices 6a to 6c one color upstream on the upstream side are integrated. To avoid the overlap of the thickness of the frame, and to eliminate the gap for mounting and adjustment,
The length of the device can be shortened in the longitudinal direction.

More specifically, compared to the conventional color image forming apparatus, the unit per color can be reduced by about 6 mm, and the total of four colors can be reduced by about 20 mm.

Incidentally, a two-component developer composed of a magnetic toner and a carrier is accommodated in the developing casing 40 of the developing devices 4a to 4d shown in FIG. Styrene acrylic is used as the toner particles, and has an average particle size of about 10 μm and is negatively charged. 30 ~ carrier particles
100 μm iron powder, a magnetic material. Magnet roller 4
1 has a plurality of N poles and S poles disposed adjacent to each other.

A voltage of about 1000 V is applied to the photosensitive drums 1 a to 1 d by the first bias applying means 45, and a voltage of 200 to 300 V is applied to the magnet roller 41 by the second bias applying means 46. And
A voltage is applied to the blades b1 to b4 by the third bias applying means 47.

The developing casing 40 is manufactured by extruding a metal material, for example, an aluminum material, and has a thickness of 1.5 mm. By forming the developing casing 40 from an aluminum material in this way, it is possible to reduce the thickness of the developing casing 40 of the developing devices 4a to 4d.

Therefore, the developing devices 4a to 4d can be reduced in size in the horizontal direction when viewed from the cross section, and in a four-tandem color electrophotographic copying machine, the developing devices 4a to 4d
Can be reduced. Therefore, the distance between the adjacent photosensitive drums 1a to 1d can be reduced, and the size of the entire color electrophotographic copying machine can be reduced.

Further, since the developing casing 40 is made of metal, the rigidity of the developing devices 4a to 4d can be increased, and the developing device does not bend downward due to its own weight. Therefore, the density unevenness of the image does not occur, and
There is no increase in the driving torque of the developing device.

Further, by making the developing casing 40 made of metal, the accuracy can be improved, and the transport auger 4 can be improved.
Even if the gap between the developing casings 2a and 42b and the developing casing 40 is 1 mm, interference or the like can be prevented. Therefore, a large stress is not applied to the developer, and the image density does not become uneven.

On the other hand, at the time of the above-described development, since a voltage of about 1000 V is applied to the photosensitive drums 1a to 1d, the photosensitive drums 1a to 1d and this photosensitive drum 1a
A of the metal developing casing 40 close to 1d
And between the photosensitive drum of one color before and the portion B of the metallic cleaning case portion 62 on the back surface side of the developing casing 40 adjacent to the photosensitive drum in some cases.

The magnet roller 41 also has a 200-
Since a voltage of 300 V is applied, the magnet roller 4
In some cases, the voltage may also leak between the portion 1 and the portions C and D of the developing casing 40 close to the magnet roller 41.

Further, since a voltage is also applied to the blades b1 to b4, the blades b1 to b4 and the blades b1 to b4
The voltage may leak between the portion E and the portion E of the developing casing 40 close to b4.

When such a voltage leak occurs, it is impossible to apply a predetermined voltage to each of the main components, so that uneven density occurs in the image. Therefore, in the present invention, the surface of the portions A to E where the voltage leakage of the developing casing 40 is likely to occur is coated with an insulating epoxy-based resin layer (coating layer) 51 to a thickness of about 100 μm. To prevent leaks.

As described above, the insulating epoxy resin layer 5
1 by coating the developing devices 4a to 4d
Can be made of metal, and the rigidity and accuracy of the developing devices 4a to 4d can be increased.

In the figure, reference numerals 52, 52 denote developing casings 40.
Are provided at both ends of the transfer auger for inserting both ends of the transport augers 42a and 42b. FIG. 5 shows a developing casing 70 according to a second embodiment of the present invention.

In the second embodiment, a portion A of the developing casing 70 where the above-described voltage leakage may occur.
To E are made of an insulating resin block material (insulating member) 71. The insulating resin block 71 is attached to the developing casing 70 with a double-sided tape.

The second embodiment has the same operation and effect as the first embodiment. Also,
FIG. 6 shows a developing casing 80 according to a third embodiment of the present invention.

In the third embodiment, a portion A of the developing casing 80 where the above-described voltage leakage may occur.
Mylar (insulating member) 8 made of P-PET (polyethylene terephthalate), 0.25 mm thick on the surface of
1 is stuck with double-sided tape.

The third embodiment has the same operation and effect as the first embodiment. The mylar 81 is effective for pasting in a narrow gap to perform insulation treatment, and is also effective in that it is an elastic body that does not easily damage the photosensitive drums 1a to 1d and the magnet roller 41.

[0069]

As described above, according to the present invention, since the developing casing is integrally formed with the case portion for the removing means for accommodating the removing means for one color before, which is located on the upstream side in the transport direction of the material to be transferred, The gap between the developing device and the removing unit can be made unnecessary. Further, since the developing casing is made of metal, the thickness of the developing casing can be reduced and the size can be reduced. Therefore, there is an effect that the size of the entire apparatus can be reduced.

Further, since the developing casing is made of metal, rigidity and precision can be improved, interference between the developing casing and the stirring and conveying means, and deformation of the developing casing due to its own weight of the developer can be prevented. A good image without density unevenness can be obtained.

In addition, since insulation is applied to the portions of the developing casing and the case for removal which are close to the image carrier, the developer supply means and the removal means, the space between the image carrier, the developer supply means and the removal means is eliminated. In this way, it is possible to prevent the occurrence of uneven image density due to the occurrence of voltage leakage without causing voltage leakage.

[Brief description of the drawings]

FIG. 1 is an internal configuration diagram showing a color electrophotographic copying machine according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing an image forming unit.

FIG. 3 is a diagram illustrating an image forming unit including a plurality of image forming units.

FIG. 4 is a perspective view showing a developing casing.

FIG. 5 is a view showing a second embodiment of a developing casing.

FIG. 6 is a view showing a third embodiment of a developing casing.

[Explanation of symbols]

 A to E: sites where voltage leaks 1a to 1d: photosensitive drums (image carriers) b1 to b4: cleaner blades (removal means) P: materials to be transferred (paper) 5a to 5d: transfer devices (transfer means) 40: Developing casing 41: Magnet roller (developer supply means) 42a, 42b: Conveyor auger (stirring / conveying means) 45, 46: Bias applying means 51: Resin layer (coating layer) 71: Resin block (insulating member) 81: Mylar (Insulating member)

Claims (9)

[Claims] An image bearing member for carrying an electrostatic latent image;
A metal developing casing for housing the developer, a developer supply means provided in the developing casing, for supplying a developer to the electrostatic latent image on the image carrier to form a developer image; Bias applying means for applying a bias to the image carrier and the developer supply means; and an insulating coating layer coated on a portion of the developing casing close to at least one of the image carrier and the developer supply means. A developing device comprising: 2. An image bearing member for carrying an electrostatic latent image,
A metal developing casing containing a two-component developer composed of a toner and a carrier; a stirring and conveying means provided in the developing casing, for stirring and conveying the two-component developer; and A developer supply unit configured to supply a two-component developer agitated and transported by the agitating and transporting unit to the electrostatic latent image on the image carrier to form a developer image; and to the image carrier and the developer supply unit. Developing means for applying a bias, and an insulating coating layer coated on a portion of the developing casing adjacent to at least one of the image carrier and the developer supplying means. apparatus. 3. An image bearing member which bears an electrostatic latent image.
A metal developing casing for housing the developer, a developer supply means provided in the developing casing, for supplying a developer to the electrostatic latent image on the image carrier to form a developer image; Bias applying means for applying a bias to the image carrier and the developer supply means; and an insulating member constituting a part of the developing casing close to at least one of the image carrier and the developer supply means. A developing device. 4. An image bearing member which bears an electrostatic latent image,
A metal developing casing containing a two-component developer composed of a toner and a carrier; a stirring and conveying means provided in the developing casing, for stirring and conveying the two-component developer; and A developer supply unit configured to supply a two-component developer agitated and transported by the agitating and transporting unit to the electrostatic latent image on the image carrier to form a developer image; and to the image carrier and the developer supply unit. A developing device comprising: a bias applying unit that applies a bias; and an insulating member that constitutes a portion of the developing casing that is adjacent to at least one of the image carrier and the developer supplying unit. 5. An image bearing member which bears an electrostatic latent image,
A metal developing casing for housing the developer, a developer supply means provided in the developing casing, for supplying a developer to the electrostatic latent image on the image carrier to form a developer image; Bias applying means for applying a bias to the image carrier and the developer supply means; an insulating member attached to a portion of the developing casing close to at least one of the image carrier and the developer supply means; A developing device comprising: 6. An image bearing member which bears an electrostatic latent image,
A metal developing casing containing a two-component developer composed of a toner and a carrier; a stirring and conveying means provided in the developing casing, for stirring and conveying the two-component developer; and A developer supply unit configured to supply a two-component developer agitated and transported by the agitating and transporting unit to the electrostatic latent image on the image carrier to form a developer image; and to the image carrier and the developer supply unit. A developing device, comprising: a bias applying unit configured to apply a bias; and an insulating member attached to a portion of the developing casing adjacent to at least one of the image carrier and the developer supplying unit. . 7. A plurality of image carriers, which are arranged at predetermined intervals along a conveying direction of a material to be transferred and carry an electrostatic latent image, are respectively opposed to these image carriers, and have different colors. A plurality of metal developing casings for accommodating a developer; and a developer supply means provided in the developing casings for supplying the developer to an electrostatic latent image on the image carrier to form a developer image. And a plurality of transfer means for transferring the developer images formed on the plurality of image carriers to the material to be transferred; and after the transfer of the developer images by the plurality of transfer means, the plurality of image carriers A plurality of removing means for removing the developer remaining on the top; and a metal case portion formed integrally with the developing casing and accommodating the one-color preceding removing means located on the upstream side in the transport direction of the transfer material. And the plurality of image carriers, developer supply means, and Voltage applying means for applying a voltage to the removing means; and an insulating coating layer coated on the developing casing and the case portion adjacent to the image carrier, the developer supplying means, and the removing means. An image forming apparatus comprising: 8. A plurality of image carriers which are arranged at predetermined intervals along a transport direction of a transfer material and carry an electrostatic latent image, and are respectively opposed to these image carriers, and have different colors. A plurality of metal developing casings for accommodating a developer; and a developer supply means provided in the developing casings for supplying the developer to an electrostatic latent image on the image carrier to form a developer image. And a plurality of transfer means for transferring the developer images formed on the plurality of image carriers to the material to be transferred; and after the transfer of the developer images by the plurality of transfer means, the plurality of image carriers A plurality of removing means for removing the developer remaining on the top; and a metal case portion formed integrally with the developing casing and accommodating the one-color preceding removing means located on the upstream side in the transport direction of the transfer material. And the plurality of image carriers, developer supply means, and Voltage applying means for applying a voltage to the removing means, and an insulating member constituting a part of the developing casing and the case part close to the image carrier, the developer supplying means, and the removing means. Image forming apparatus. 9. A plurality of image carriers which are arranged at predetermined intervals along a conveying direction of a material to be transferred and carry an electrostatic latent image, and are respectively opposed to these image carriers and have different colors. A plurality of metal developing casings for accommodating a developer; and a developer supply means provided in the developing casings for supplying the developer to an electrostatic latent image on the image carrier to form a developer image. And a plurality of transfer means for transferring the developer images formed on the plurality of image carriers to the material to be transferred; and after the transfer of the developer images by the plurality of transfer means, the plurality of image carriers A plurality of removing means for removing the developer remaining on the top; and a metal case portion formed integrally with the developing casing and accommodating the one-color preceding removing means located on the upstream side in the transport direction of the transfer material. And the plurality of image carriers, developer supply means, and Voltage applying means for applying a voltage to the removing means, and an insulating member attached to a portion of the developing casing and the case portion adjacent to the image carrier, the developer supplying means, and the removing means. Characteristic image forming apparatus.