JP3436716B2 - Toner recycling type image forming apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine, a printer,
The present invention relates to an image forming apparatus such as a facsimile,
In particular, the present invention relates to a toner recycling type image forming apparatus in which collected toner is recycled into a developing device for use.

[0002]

2. Description of the Related Art In an image forming apparatus typified by a copying machine, the surface of a photosensitive drum is uniformly charged, and an electrostatic latent image corresponding to an original image is formed on the surface of the photosensitive drum by imagewise exposure. The electrostatic latent image is developed by the developer filled in the developing device to form a toner image on the surface of the photoconductor drum, and the toner image is transferred from the surface of the photoconductor drum onto a transfer paper. An image is formed by fixing the image with heat, pressure or the like. The toner remaining on the surface of the photoconductor drum after the toner image transfer is removed by a cleaning device such as a cleaning blade, and the surface of the photoconductor drum is destaticized, whereby one cycle of image formation is completed. Image formation is performed. In such an image forming apparatus, recently, from the viewpoint of resource saving, environmental friendliness, etc., after the toner image is transferred onto a predetermined transfer material, the toner removed from the surface of the photoconductor and collected is used for the above-mentioned development. 2. Description of the Related Art Collected toner recycling type image forming apparatuses that are recycled and reused in the apparatus are widely used.

In recent years, so-called digital image forming apparatuses such as color copying machines, facsimiles, laser printers and the like have become widespread. In such digital image forming apparatuses, a reversal developing method is adopted. . The reversal development method is different from the regular development method used in a normal analog image forming apparatus, and uses toner charged to the same polarity as the charging polarity of the photoconductor and uses a light attenuating unit (light The electrostatic image is developed by attaching charged toner to the irradiation part). That is, since the portion not irradiated with light (the background portion) is a high-potential portion having the same polarity as the charged toner, the charged toner does not adhere to the charged toner, and only the light attenuating portion where the potential is lowered by the irradiation of the light is charged toner. Is attached, a toner image corresponding to the electrostatic image is formed.

[0004]

However, when an image is formed by the reversal development method, when the toner collected by the cleaning device is recycled into the developing device and reused for development, the image formation is repeated according to the following conditions. There is a problem that the quality of the image formed is degraded. That is, the toner used for development contains a charge control agent and the like, and the toner is triboelectrically charged to a predetermined polarity (the same polarity as the charging polarity of the photoconductor) by friction mixing and stirring in the developing device. However, such a charged toner always contains a reversely charged toner, which is charged in the opposite polarity, though it is a very small amount. When development is performed with a developer containing such reversely charged toner, most of the reversely charged toner remains on the surface of the photosensitive drum after transfer and is collected by a cleaning device. Therefore, when the toner collected by the cleaning device is recycled and reused in the developing device, the amount of the oppositely charged toner in the developing device gradually increases as the image formation is repeated. As a result, various inconveniences such as a decrease in image density, fog, and toner scattering occur. Particularly in the reversal development, the background portion of the image is not irradiated with light and is held at the same polarity as the charged toner and at a high potential, so that the oppositely charged toner is extremely likely to adhere to this portion. Therefore, when the amount of the reversely charged toner increases, the reversely charged toner adheres to the white paper portion of the image, and the image quality deterioration such as toner scatter of the image portion remarkably appears.

Paper dust is generated from the transfer paper, and the paper dust attached to the surface of the photosensitive drum is also collected with the toner by the cleaning device and supplied into the developing device. It is known that the paper dust generated from the transfer paper is generally negatively charged, and when an image is formed using a negatively charged toner as a developer, the paper dust is a regular charged toner (negatively charged toner). The same behavior as described above is exhibited, and since it is embedded in the normally charged toner in the formed image, the deterioration of the image quality due to the paper dust is at a negligible level. However, when image formation is performed using the positively charged toner as a developer, the image quality is significantly deteriorated. That is, in this case, the paper powder behaves exactly like the oppositely charged toner (negatively charged toner), causing not only the above-mentioned inconvenience but also when the paper powder is mixed with the toner, the toner adheres around the paper powder. And then aggregate. When development is performed with such agglomerated toner, the image quality deterioration such as the toner scattering in the image area becomes more remarkable.

In order to prevent the deterioration of image quality due to the above-mentioned reversely charged toner and paper powder, for example, in Japanese Patent Laid-Open No. 9-114217, two developer stirring and mixing members (spiral or paddle) provided in a developing device are provided. It is disclosed that a conductive mesh member is provided between and the bias voltage having the same polarity as that of the charged toner is applied to the conductive mesh member. In the image forming apparatus disclosed in this prior art, all the toner collected by the cleaning device is supplied to the developing area through the conductive mesh member, and the reverse charging toner, paper dust, or paper dust is supplied. The agglomerated toner containing the particles is captured by the conductive mesh, which prevents the introduction of the oppositely charged toner into the developing area and avoids the above-mentioned deterioration in image quality.

However, the above-mentioned image forming apparatus of the prior art still has various problems to be improved. For example, if the mesh member is clogged, the flow of the developer is stopped, and a sufficient amount of the developer (charged toner) is not supplied to the development area, which makes the development itself difficult. Further, when the toner passes through the openings of the mesh, there is also a problem that the toner is crushed and solidified. Moreover, since this mesh member is arranged at a position where it is embedded in the developer,
It is very difficult to clean or replace the clogged mesh member. Furthermore, a special power source for applying a bias voltage to this mesh member is required, which is unsuitable in that the device is made compact.

Therefore, an object of the present invention is to effectively prevent the deterioration of the image quality due to the mixing of the oppositely charged toner and the paper powder into the developing device, and the toner capable of stably forming the high quality image by the reversal development. It is to provide a recycle-type image forming apparatus. Another object of the present invention is to facilitate cleaning and replacement of the mesh member for capturing the oppositely charged toner and paper powder, and applying a bias voltage to the mesh member without using a special power source. Another object of the present invention is to provide a toner recycling type image forming apparatus capable of easily capturing an oppositely charged toner or the like.

[0009]

According to the present invention, a toner image is formed by developing an electrostatic image formed on the surface of a photosensitive drum by reversal development using a magnetic developer filled in a developing device. Forming a toner image, transferring the toner image onto a predetermined transfer paper, collecting toner remaining on the surface of the photosensitive drum after the toner image transfer by a cleaning device, and recycling the collected toner into the developing device. In the recycle type image forming apparatus, the developing device has a developing housing filled with a magnetic developer and having an open upper portion and a side portion facing the photosensitive drum, and the developing housing facing the photosensitive drum. And a lid body detachably attached so as to cover the upper portion of the developing housing. The inner surface of the lid body Has a plate-shaped conductive mesh attached thereto, and is set so that the developing bias voltage applied to the developer carrying sleeve at the time of development is also applied to the conductive mesh through a rectifier. An image forming apparatus is provided.

According to the present invention, a plate-shaped conductive mesh is provided on the inner surface of the lid which is detachably mounted in the opening of the developing housing of the developing device. It captures paper dust, paper dust, or agglomerated toner containing paper dust. That is, this conductive mesh is provided on the inner surface of the lid, and is not embedded in the flow in which the developer is agitated and mixed. Therefore, the conductive mesh can be easily cleaned or replaced by opening the lid, and the clogging of the conductive mesh does not stop the flow of the developer. The supply of charged toner between the drum and the developer transport sleeve) is not impaired.

A developing bias voltage applied to the developer carrying sleeve (developing sleeve) is also applied to the conductive mesh. That is, this developing bias voltage is
The potential of the developing sleeve is held at the same polarity as that of the regular charged toner, and the conductive mesh is also held at the potential of the same polarity as that of the regular charged toner. Therefore, only the oppositely charged toner is selectively captured by the conductive mesh from the toner floating or scattered in the developing device by electrostatic attraction. Further, when the development is performed using the positively charged toner, the paper dust is negatively charged, and therefore the application of the developing bias voltage as described above causes the paper dust and the aggregated toner containing the paper dust to be reversed. It is captured in the same manner as the charged toner (negatively charged toner). Furthermore, the application of the developing bias voltage to the conductive mesh needs to be performed via a rectifier such as a diode. That is, the developing bias voltage is applied to the developing sleeve at the time of image formation (at the time of development), but at the time of non-image formation (when the surface of the photoconductor is not mainly charged), the charged toner is not applied to the surface of the photoconductor. In order to prevent the adhesion, a bias voltage opposite to the developing bias voltage is applied. If such a reverse voltage is applied to the conductive mesh, not only the captured reversely charged toner and paper powder are released,
The regular charged toner is captured. Therefore, it is necessary to avoid applying the reverse bias voltage by applying the developing bias voltage via the rectifier.
Further, in the present invention, in order to apply the developing bias voltage to the conductive mesh as described above, the power source for applying the developing bias voltage to the developing sleeve can be shared, and it is necessary to use a special power source. There is an advantage that it does not.

In the above-described present invention, the developing housing is provided with the developer stirring and mixing area adjacent to the developing sleeve and the collected toner storage area adjacent to the developer stirring and mixing area, and on the collected toner storage area. It is preferable to provide the conductive mesh on the inner surface of the lid located. That is, the toner collected by the cleaning device is supplied to the collected toner storage area, and the supplied collected toner is collected by the scooping paddle arranged in the storage area. It is introduced into the developer stirring and mixing area, and is supplied from the developer stirring and mixing area to the developing sleeve to perform development. By disposing the conductive mesh on the inner surface of the lid on the collected toner storage area, it is possible to efficiently capture the reversely charged toner contained in the collected toner, the paper dust, and the aggregated toner containing the paper dust. Further, in this case, by arranging the inner surface of the lid provided with the conductive mesh at a position close to the upper end of the scooping paddle, it is possible to more efficiently capture the reversely charged toner and the like.

Further, according to the present invention, instead of providing the above-mentioned conductive mesh, the upper portion of the developing sleeve is
It is also possible to rotatably attach a metal front cover to the lid and apply a developing bias voltage to the lid via a rectifier. In this case, immediately before the developer is supplied to the developing area, it is possible to effectively capture the reversely charged toner, paper dust, etc., and effectively prevent the deterioration of the image quality due to the reversely charged toner or the like. Moreover, since the metal front cover can be easily opened, it can be easily cleaned by cleaning it.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to specific examples shown in the accompanying drawings. FIG. 1 is a diagram showing a structure of a collected toner recycling type image forming apparatus of the present invention, and FIG. 2 is a diagram showing a main part of an image forming apparatus of another example of the present invention.

In FIG. 1, in this image forming apparatus, a main charging device 2, an exposure mechanism 3, a developing device 4, a transfer device are provided around a photosensitive drum 1 which is rotatably provided in the direction of the arrow in the drawing. 5, cleaning device 6, static eliminator 7
The transfer paper 10 is arranged in this order along the rotation direction of the photoconductor drum 1, the transfer paper 10 is passed between the photoconductor drum 1 and the transfer device 5, and the fixing device is provided on the discharge path of the transfer paper 10. (Not shown).

The photosensitive drum 1 is an inorganic photosensitive drum in which a photosensitive layer such as selenium or amorphous silicon is provided on a conductive base roller such as aluminum, or a charge generating agent or a charge transporting agent in a binder resin. An organic photosensitive drum provided with an organic photosensitive layer in which is dispersed is used. As the main charging device 2, there is also a roller type contact charging device, but in general, a corona charger is used, and the surface (photosensitive layer) of the photosensitive drum 1 is a kind of photosensitive layer by the main charging device 2. Is uniformly charged to a predetermined polarity. At this time, the main charging potential of the surface of the photoconductor is usually 200 to 1000 V (absolute value). Next, the image exposure mechanism 3 irradiates the surface of the photosensitive drum with dot light such as a laser beam corresponding to the document by reflected light of the document or an electric signal from a computer or the like, and the potential of the light-irradiated portion is attenuated by light and electrostatic. A latent image is formed.

This electrostatic latent image is developed by magnetic brush development using a developing device 4 described later, and a toner image is formed on the surface of the photosensitive drum 1. As the developer, a two-component developer composed of a magnetic carrier and an insulating toner or a one-component developer composed of a magnetic toner is used, and the toner frictionally charged to a predetermined polarity by the developing device 4 is used as a magnetic brush. The electrostatic latent image formed on the surface of the photoconductor drum 1 is developed by this toner, and a toner image is formed on the surface of the photoconductor drum 1. In the present invention, since the electrostatic latent image is developed by reversal development, the charging polarity of the toner is the same as the charging polarity of the surface of the photoconductor drum 1, and the potential is attenuated by the light irradiation by image exposure. The charged toner is attached and the electrostatic latent image is developed (that is, a toner image is formed). At the time of this development, a developing bias voltage is applied between the developer carrying sleeve 32 housed in the developing device 4 described later and the photosensitive drum 1 (absolute value of about 300 to 700 V).

Below the developing device 4, there is provided a paper feed guide 12 for guiding the transfer paper 10 to a transfer region (a region between the transfer device 5 and the photosensitive drum 1). A suction duct 13 is arranged on the paper guide 12, that is, immediately below the developing device 4, and exhausts the toner scattered from the developing area during development. This prevents the inside of the apparatus from being contaminated by the scattered toner.

The transfer device 5 is generally a transfer charger 5a.
And a separation charger 5b, and a transfer paper 1 introduced between the transfer device 5 and the photosensitive drum 1.
The back surface of 0 is charged to the opposite polarity to the toner image by the transfer charger 5a, and the toner image is transferred onto the transfer paper 10 by the electrostatic attraction between the charge and the toner image. Also,
Simultaneously with the transfer of the toner image, the separation charger 5b is AC-charged so that the transfer paper 10 is quickly separated from the surface of the photosensitive drum 1. A transfer roller can be used as the transfer device 5, and in this case, a transfer paper separating device such as the separating charger 5a is not necessary.

The transfer paper 10 on which the toner image has been transferred is conveyed to a fixing device (not shown) and is heated by heat or pressure.
The toner image is fixed on the surface of the transfer paper 10. On the other hand, after the toner image is transferred onto the transfer paper 10, the cleaning device 6 having a cleaning blade or the like scrapes off and collects the toner remaining on the surface of the photosensitive drum 1,
The surface charge of the photoconductor drum 1 is removed by the light irradiation by the static eliminator 7, and the next image forming process is performed.
The toner collected by the cleaning device 6 is recycled to the developing device 4 for reuse by using a conveying device such as a spiral according to a route indicated by 20.

In the above-described image forming apparatus, the developing device 4 has a developing housing 30 whose upper portion and a side portion facing the photosensitive drum 1 are open, and a developing housing 4 which is attached to and detached from the housing 30 so as to cover the upper portion of the developing housing 30. It is composed of a lid 31 freely attached. Developing housing 30
A developer 25 is filled therein, and a developer carrying sleeve (developing sleeve) 32 is arranged so as to face the photosensitive drum 1, and the developer stirring and mixing area is adjacent to the developing sleeve 31. 33 is formed. As is apparent from FIG. 1, the developer stirring paddles 33a and 33b extending in the same axis as the developing sleeve 32 are arranged in parallel in the developer stirring and mixing area 33. The paddles 33a and 33b are arranged in parallel with each other. A feed guide 34 is provided between them. Further, a collected toner storage area 36 partitioned by a relatively short partition wall 35 is formed adjacent to the developer agitation / mixing area 33, and the collected toner storage area 36 has a pumping paddle 37. Is housed.
As is apparent from FIG. 1, the toner collected by the cleaning device 6 is supplied to the bottom of the collected toner storage area 36 and is pumped up by the scooping paddle 37.

A magnet having a plurality of magnetic poles is fixed inside the developing sleeve 32, and the developer 25 is conveyed in the form of a magnetic brush by the rotation of the sleeve. The developing sleeve 32 and the drum 1 are spaced from each other. , Generally 0.3
It is set to about 1.0 mm. Of course, the developing sleeve 32 may be one in which the developer is conveyed by fixing the sleeve and rotating the magnet inside. In addition, the developing sleeve 32 and the developing sleeve 32 have a constant interval (usually 0.5 to 5).
(About 0.9 mm) is placed and the spike cutting blade 38 is attached. That is, the developer 25 drawn up by the developing sleeve 32 is blocked by the spike-cutting blade 38, and is formed in the developing area in the form of a magnetic brush adjusted to have a constant spike length (of the photosensitive drum 1 and the developing sleeve 32). The electrostatic latent image is developed in this area.

A power supply 40 is connected to the developing sleeve 32, so that a developing bias voltage is applied during development (at the time of image formation). That is, when reverse development is performed using positively charged toner, a developing bias voltage of about +300 to +700 V is applied to the developing sleeve 32,
When negatively charged toner is used, a developing bias voltage of about -300 to -700V is applied. By applying such a developing bias voltage, the transfer of the charged toner to the electrostatic latent image portion is promptly performed. In addition, during non-image formation, for example, when the main switch of the apparatus is turned on, when the shutoff of the apparatus is released, or during the period from the end of the image forming cycle to the stop of the rotation of the photosensitive drum 1, In order to prevent the charged toner from adhering to the surface of the photosensitive drum 1, the power source 40 applies a reverse bias voltage (that is, the developing bias voltage has the same absolute value but opposite polarity). As a result, wasteful consumption of charged toner and toner contamination on the surface of the photosensitive drum are prevented.

The developer agitating paddles 33a and 33b provided in the developer agitating and mixing area 33 sufficiently agitate the toner in the developer 25 by mixing and agitating the developer 25. The blades of the paddles 33a and 33b are set in a spiral shape so as to agitate and feed the developer 25 in the axial direction, for example, and the feed guide 34 disposed between these paddles is shown in FIG. Although not provided, a communication part is formed at the center or both ends. That is, these developer stirring paddles 33a, 33
By b, while the developer 25 is agitated and fed in the axial direction, the developer 25 is taken in and out between the center portion or both end portions of the feed guide 33 existing between both paddles, so that the frictional charging is efficiently performed. It has become. In this way, the developer (toner) 25 frictionally charged to a predetermined polarity is drawn up by the developing sleeve 32, and the developer is conveyed to the developing area in the form of a magnetic brush whose ear length is adjusted by the ear cutting blade 38. The electrostatic latent image is developed.

The scooping paddle 37 provided in the collected toner storage area 36 is adjacent to the developer stirring paddle 33b, which is located away from the developing sleeve 32, in parallel with the paddle 33b via the partition wall 35. ing. That is, the collected toner supplied to the collected toner storage area 36 is scooped up by the scooping paddle 37, and the partition wall 3
5 to the developer agitating paddle 33b arranged adjacently.

In the present invention, the lid 31 mounted on the developing housing 30 descends above the collected toner storage area 36, and its inner surface is located near the upper end of the scooping paddle 37. A metallic cover 45 is rotatably attached to the lid 31 above the developing sleeve 32. The metal cover 45 is positioned by an elastic member 46 so as to close the upper portion of the developing sleeve 32.

According to the present invention, the plate-shaped conductive mesh 50 made of metal net or the like is attached to the inner surface of the lid 31 located on the collected toner storage area 36, and the developing bias is applied to the developing sleeve 32 described above. A developing voltage is also applied to the conductive mesh 50 via a rectifier 51 such as a diode by a power supply 40 that applies a voltage. That is, the conductive mesh 50 is held at the potential of the same polarity as the regular charged toner by the developing voltage, and the conductive mesh 50 is arranged near the upper end of the scooping paddle 37. As a result, when the collected toner supplied into the collected toner storage area 36 is transferred to the developer stirring and mixing area 33 by the scooping paddle 37, the reversely charged toner is efficiently captured by the conductive mesh 50. In this case, when the development is performed by using the positively charged toner, the conductive mesh 5 is applied by the development bias voltage.
Since 0 is held at a positive potential, negatively charged paper powder or agglomerated toner containing paper powder is also captured by the conductive mesh 50, similarly to the reversely charged toner (negatively charged toner). It will be. Particularly, the paper dust is caught in the mesh of the conductive mesh 50, so that the trapping is efficiently performed.

As described above, the conductive mesh 50 captures the oppositely charged toner, the paper powder, or the agglomerated toner containing the paper powder when the collected toner is pumped up and moved to the developer stirring and mixing area 33 by the paddle 37. Therefore, it is preferable to have a size substantially corresponding to the pumping paddle 37. Further, in order to efficiently capture the oppositely charged toner and the like, it is desirable that the mesh has a mesh opening of about 30 to 150 μm.

The application of the developing bias voltage to the conductive mesh 50 must be performed via the rectifier 51. As described above, the reverse bias voltage (reverse polarity to the developing voltage) is applied by the power supply 40 in the state where the photosensitive drum 1 is driven and rotated during non-image formation. Therefore,
When the developing bias voltage is directly applied to the conductive mesh 50 by the power source 40, the reverse bias voltage is applied to the conductive mesh 50, the trapped reversely charged toner and the like are discharged, and the polarity is changed to the normal polarity. The charged toner is captured. Therefore, it is necessary to apply the developing bias voltage via the rectifier 51.

In the example described above, the conductive mesh 50
Is attached to the inner surface of the lid 31 located on the collected toner storage area 36. However, since the toner is full in the developing device 4, the lid 31 on the developer stirring and mixing area 33 is covered. Although it is possible to attach the conductive mesh 50 to the inner surface, the conductive mesh 50 is preferably arranged on the collected toner storage area 36 in order to most efficiently capture the oppositely charged toner and the like.

In the present invention, the electrically conductive mesh 50 provided on the inner surface of the lid 31 that is detachably attached to the developing housing 30 captures the oppositely charged toner and paper dust. Therefore, even if the mesh 50 is clogged or the like, the supply of the developer to the developing sleeve 32 is not impaired, and a constant amount of the developer is always supplied for the development. 5
The cleaning and replacement of 0 can be performed very easily.

In the present invention, instead of the above-mentioned conductive mesh 50, a metal cover 45 located above the developing sleeve 32 can be used to capture the oppositely charged toner and paper dust. An example using such a metal cover is shown in FIG.

That is, as shown in FIG. 2, a power supply 40 and a rectifier 51 are attached to a metallic lid 45 rotatably attached to the lid 31, similarly to the conductive mesh 50 described above.
The developing bias voltage is applied via the. As a result, immediately before the developer 25 is supplied to the developing area, the reversely charged toner, the paper dust, and the aggregated toner containing the paper dust are captured on the inner surface of the metal cover 45, and are generated by the development by the reversely charged toner or the like. It is possible to effectively prevent deterioration of image quality. In this example, the developing bias voltage is applied via the rectifier 51 to prevent the reverse bias voltage at the time of non-image formation from being applied to the metal cover 45, as in the above example. Even in such an image forming apparatus, since the metal cover 45 is rotatably provided, the cleaning thereof can be performed very easily.

[0034]

According to the present invention, the toner collected by the cleaning device can be recycled into the developing device without supplying the oppositely charged toner to the developing region, and the deterioration of the image quality due to paper dust or the like is effective. Can be prevented.
Further, when the development is performed using the positively charged toner, the paper dust and the aggregated toner containing the paper dust can be captured together with the oppositely charged toner. In particular, when the conductive mesh is used, the paper dust is caught in the mesh of the mesh, so that the paper dust can be efficiently captured.

[Brief description of drawings]

FIG. 1 is a diagram showing a structure of a collected toner recycling type image forming apparatus of the present invention.

FIG. 2 is a diagram showing a main part of an image forming apparatus according to another example of the present invention.

[Explanation of symbols]

1: Photoreceptor drum 4: Developing device 6: Cleaning device 20: Recycle path of collected toner 25: Developer 30: Developing housing 31: Lid 32: Developing sleeve 33: Developer stirring and mixing area 33a, 33
b: developer stirring paddle 36: collected toner storage area 37: pumping paddle 40: power supply 45: metal cover 50: plate-shaped conductive mesh 51: rectifier

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinji Kikuta 1-2-2 Tamatsukuri, Chuo-ku, Osaka Mita Kogyo Co., Ltd. (72) Yuzuru Nanjo 1-2-2 Takumazo, Chuo-ku, Osaka Mita Kogyo Incorporated (72) Inventor Noriyuki Sakata 1-228 Tamatsukuri, Chuo-ku, Osaka Mita Industry Co., Ltd. (56) Reference JP-A-6-186849 (JP, A) JP-A-9-134104 (JP , A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 13/06-13/095 G03G 15/06-15/095

Claims (5)

(57) [Claims] 1. An electrostatic image formed on the surface of a photosensitive drum is developed by reversal development using a magnetic developer filled in a developing device to form a toner image, and the toner image is formed in a predetermined size. A toner recycle type image forming apparatus for transferring toner onto a transfer paper, collecting toner remaining on the surface of a photoconductor drum after transferring a toner image with a cleaning device, and recycling the collected toner into the developing device. Includes a developing housing filled with a magnetic developer and having an open upper portion and a side portion facing the photoconductor drum, and a developer carrying sleeve arranged in the developing housing so as to face the photoconductor drum. , A lid that is detachably attached so as to cover the upper portion of the developing housing, and a plate-shaped conductive mesh is provided on the inner surface of the lid. And is attached, a developing bias voltage applied to the developer carrying sleeve upon development, to the conductive mesh, the image forming apparatus characterized by being configured to be applied through the rectifier. 2. The developing housing is provided with a developer agitating and mixing area having a developer agitating and mixing paddle adjacent to the developer conveying sleeve, and a scooping paddle adjacent to the developer agitating and mixing area. The collected toner storage area to which the toner collected by the cleaning device is supplied is formed, and the conductive mesh is attached to the inner surface of the lid located above the collected toner storage area. Image forming device. 3. The inner surface of the lid on the collected toner storage area is
The image forming apparatus according to claim 2, wherein the image forming apparatus is arranged at a position near an upper end of the scooping paddle. 4. The image forming apparatus according to claim 1, wherein a positively charged toner is used as the magnetic developer. 5. An electrostatic image formed on the surface of a photosensitive drum is developed by reversal development using a magnetic developer filled in a developing device to form a toner image, and the toner image is formed in a predetermined size. In the collected toner recycling type image forming apparatus, the toner remaining on the surface of the photoconductor drum after the toner image transfer is collected by a cleaning device, and the collected toner is recycled into the developing device, while being transferred onto a transfer paper. The developing device includes a developing housing that is filled with a magnetic developer and has an open upper portion and a side portion that faces the photosensitive drum, and a developer transport unit that is disposed in the developing housing so as to face the photosensitive drum. A sleeve and a lid detachably attached so as to cover the upper part of the developing housing, and the upper part of the developer carrying sleeve has: A metal front cover is rotatably attached to the lid so that the developing bias voltage applied to the developer carrying sleeve during development is also applied to the metal front cover via a rectifier. An image forming apparatus characterized by being set.