JP2001175061A - Toner recycling system image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner recycling system image forming device capable of effectively preventing the deterioration of image quality caused by the intrusion of reversely charged toner and paper powder into a developing device, and capable of stably forming an image of high image quality by reversal developing. SOLUTION: In the toner recycling system image forming device for recovering the toner remaining on the surface of a photoreceptor drum after a toner image is transferred by a cleaning device, and then, recycling the recovered toner in the developing device, the developing device is provided with a developing housing which is packed with developer and whose upper part and side part facing the photoreceptor drum are open, a developer carrying sleeve arranged in the developing housing, and a cover body which is freely attachably/detachably attached so as to cover the upper part of the developing housing, besides, a plate-like conductive mesh is mounted at the inner surface of the cover body, and the developing device is set so that a developing bias voltage applied to the developer carrying sleeve at developing may be also applied to the conductive mesh through a rectifier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer,
Related 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 and used in a developing device.

[0002]

2. Description of the Related Art In an image forming apparatus represented by a copying machine, the surface of a photosensitive drum is uniformly charged, and an electrostatic latent image corresponding to a document image is formed on the surface of the photosensitive drum by image exposure. The electrostatic latent image is developed with a developer filled in a developing device to form a toner image on the surface of the photosensitive drum, and the toner image is transferred from the surface of the photosensitive drum onto transfer paper, and the transferred toner is The image is formed by fixing the image by heat, pressure, or the like. The toner remaining on the surface of the photoconductor drum after the transfer of the toner image is removed by a cleaning device such as a cleaning blade, and further, the surface of the photoconductor drum is neutralized, thereby completing one cycle of image formation. Is performed. In such an image forming apparatus, recently, from the viewpoint of resource saving and environmental friendliness, after transferring a toner image onto a predetermined transfer material, the toner removed from the photoreceptor surface and collected is subjected to the above-described development. 2. Description of the Related Art A recycled toner recycling type image forming apparatus that is recycled into an apparatus and reused is widely used.

In recent years, so-called digital image forming apparatuses such as a color copying machine, a facsimile, and a laser printer have become widespread. In such digital image forming apparatuses, a reversal developing method is employed. . The reversal development method is different from the regular development method used in a normal analog image forming apparatus, and uses a toner charged to the same polarity as the charging polarity of the photoreceptor, and uses a light attenuating section (light The electrostatic image is developed by attaching the charged toner to the irradiation unit). That is, since the portion not irradiated with light (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 the charged toner is charged only to the light attenuated portion whose potential has been reduced by light irradiation. Adheres to form a toner image corresponding to the electrostatic image.

[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 as follows. There is a problem that the image quality of the formed image is deteriorated. That is, a charge control agent or the like is mixed in the toner to be developed, and the toner is frictionally charged to a predetermined polarity (the same polarity as the charging polarity of the photoconductor) by frictional mixing and stirring in the developing device. However, such a charged toner contains a small amount of a reversely charged toner which is always charged to the opposite polarity. When development is performed using a developer containing such a reversely charged toner, most of the reversely charged toner remains on the surface of the photoreceptor drum after the transfer, and is collected by the 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 reduction in image density, fog, and toner scattering occur. In particular, in reverse development, the background portion of the image is not irradiated with light and is kept at the same polarity and high potential as the charged toner, so that the oppositely charged toner is very likely to adhere to this portion. Therefore, when the amount of the oppositely charged toner increases, the oppositely charged toner adheres to the blank image portion of the image, and the image quality such as toner scattering of the image portion is significantly reduced.

Further, paper dust is generated from the transfer paper, and the paper dust attached to the surface of the photosensitive drum is also collected together with the toner by the cleaning device and supplied to the developing device. It is generally known that paper dust generated from transfer paper is negatively charged. When an image is formed using a negatively charged toner as a developer, the paper dust is a regular charged toner (negatively charged toner). In the image to be formed, the embedded image is embedded in the regular charged toner, so that the deterioration of the image quality due to the paper dust is at a negligible level. However, when an image is formed using a positively charged toner as a developer, the image quality is significantly reduced. That is, in this case, the paper powder behaves exactly the same as the oppositely charged toner (negatively charged toner), causing the above-described inconvenience, and when the paper dust is mixed with the toner, the toner adheres around the paper powder. And aggregate. When the development is performed with such agglomerated toner, image quality deterioration such as toner scattering of the image portion described above becomes more remarkable.

In order to prevent the image quality from being degraded due to the oppositely charged toner and paper powder, for example, Japanese Patent Application Laid-Open No. Hei 9-114217 discloses two developer stirring / mixing members (spiral or paddle) provided in a developing device. It is disclosed that a conductive mesh member is provided between the conductive mesh members and a 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 a development area through a conductive mesh member, and the reversely charged toner, paper dust, or paper dust is removed. This is to trap the aggregated toner contained in the conductive mesh, thereby preventing introduction of the oppositely charged toner or the like into the development area and avoiding the above-described deterioration in image quality.

[0007] However, the above-mentioned prior art image forming apparatus 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, so that the development itself becomes difficult. There is also a problem that when the toner passes through the openings of the mesh, 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. Further, a special power supply for applying a bias voltage to the mesh member is required, which is unsuitable in terms of making the apparatus compact.

Accordingly, it is an object of the present invention to provide a toner capable of effectively preventing deterioration in image quality due to the incorporation of oppositely charged toner or paper dust into a developing device and capable of stably forming a high quality image by reversal development. An object of the present invention is to provide a recycling type image forming apparatus. Another object of the present invention is to easily perform cleaning and replacement of a mesh member that captures oppositely charged toner and paper dust, and to apply a bias voltage to the mesh member without using a special power supply. Another object of the present invention is to provide a toner recycling type image forming apparatus capable of easily capturing a reversely charged toner or the like.

[0009]

According to the present invention, 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 transferring the toner image onto a predetermined transfer paper, collecting the toner remaining on the surface of the photosensitive drum after the transfer of the toner image by a cleaning device, and recycling the collected toner into the developing device. In the recycling type image forming apparatus, the developing device is filled with a magnetic developer and has an upper portion and a side facing the photosensitive drum that are open, and a photosensitive drum facing the inside of the developing housing. And a lid detachably attached so as to cover an upper portion of the developing housing, and an inner surface of the lid. Has a plate-shaped conductive mesh attached, and is set so that a developing bias voltage applied to the developer transport sleeve during development is also applied to the conductive mesh via a rectifier. An image forming apparatus is provided.

In the present invention, a plate-shaped conductive mesh is provided on the inner surface of a lid detachably attached to the opening of the developing housing of the developing device. It captures aggregated toner containing paper, paper powder, or paper powder. That is, the conductive mesh is provided on the inner surface of the lid, and is not embedded in the flow in which the developer is stirred and mixed. Therefore, the conductive mesh can be easily cleaned or replaced by opening the lid, and the flow of the developer is not stopped by the clogging of the conductive mesh. The supply of charged toner to the drum (between the drum and the developer transport sleeve) is not impaired.

Further, a developing bias voltage applied to the developer conveying sleeve (developing sleeve) is also applied to the conductive mesh. That is, this developing bias voltage is
The potential of the developing sleeve is maintained at the same polarity as the regular charged toner, and the conductive mesh is also maintained at the same polarity as the regular charged toner. Accordingly, only the oppositely charged toner is selectively captured by the conductive mesh by electrostatic attraction from the toner floating or scattering in the developing device. Further, when the development is performed using the positively charged toner, the paper dust is charged to the negative polarity, so that the application of the development bias voltage as described above also causes the paper dust and the aggregated toner including the paper dust to be reversed. It is captured similarly to the charged toner (negatively charged toner). Further, the application of the developing bias voltage to the conductive mesh needs to be performed through a rectifier such as a diode. That is, a 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 main-charged), the charged toner is applied to the surface of the photoconductor. In order to prevent 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 will the captured oppositely charged toner or paper powder be released,
Normally charged toner is captured. Therefore, it is necessary to avoid applying a reverse bias voltage by applying a developing bias voltage via a rectifier.
Further, in the present invention, in order to apply the developing bias voltage to the conductive mesh as described above, a power supply for applying the developing bias voltage to the developing sleeve can be shared, and it is necessary to use a special power supply. There is no advantage.

In the above-described present invention, the developing housing is provided with a developer stirring and mixing area adjacent to the developing sleeve and a collected toner storage area adjacent to the developer stirring and mixing area. Preferably, the conductive mesh is provided on the inner surface of the lid. That is, the toner collected by the cleaning device is supplied to the collected toner storage area, and the supplied collected toner is developed by the pumping paddle arranged in the storage area, where the developer stirring and mixing paddle is arranged. The developer is introduced into the mixing and mixing area, and is supplied to the developing sleeve from this mixing and mixing area for development. By arranging the conductive mesh on the inner surface of the lid inside the collected toner storage area, the reversely charged toner, paper powder, and aggregated toner including paper powder contained in the collected toner can be efficiently captured. In this case, by arranging the inner surface of the lid on which the conductive mesh is provided at a position near the upper end of the pumping paddle, it is possible to more efficiently capture the oppositely charged toner and the like.

According to the present invention, instead of providing the above-described conductive mesh, an upper portion of the developing sleeve is provided.
A front cover made of metal may be rotatably attached to the lid, and a developing bias voltage may be applied to the lid via a rectifier. In this case, immediately before the developer is supplied to the developing area, the oppositely charged toner, paper dust, and the like can be effectively captured, and the deterioration of the image quality due to the oppositely charged toner and the like can be effectively prevented. In addition, since the front cover made of metal can be easily opened, cleaning and the like can be easily performed.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to specific examples shown in the accompanying drawings. FIG. 1 is a view showing a structure of a recovered toner recycling type image forming apparatus of the present invention, and FIG. 2 is a view 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 exposing mechanism 3, a developing device 4, a transfer device are provided around a photosensitive drum 1 rotatably provided in the direction of the arrow in FIG. 5, cleaning device 6, static elimination device 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 a fixing device is provided on a discharge path of the transfer paper 10. (Not shown) is provided.

As the photosensitive drum 1, an inorganic photosensitive drum in which a photosensitive layer such as selenium or amorphous silicon is provided on a conductive base roller of aluminum or the like, 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 a roller-type contact charging device, but generally, a corona charger is used, and the main charging device 2 causes the surface (photosensitive layer) of the photosensitive drum 1 to change the type of the photosensitive layer. , And is uniformly charged to a predetermined polarity. At this time, the main charging potential of the photoreceptor surface is usually 200 to 1000 V (absolute value). Next, the image exposure mechanism 3 irradiates the surface of the photoreceptor drum with dot light such as a laser beam corresponding to the original by reflected light of the original or an electric signal from a computer or the like. A latent image is formed.

The 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. The electrostatic latent image formed on the surface of the photosensitive drum 1 is developed by the toner, and a toner image is formed on the surface of the photosensitive drum 1. In the present invention, since the electrostatic latent image is developed by reversal development, the charged polarity of the toner is the same as the charged polarity on the surface of the photosensitive drum 1, and the toner is charged in a portion where the potential is attenuated by light irradiation by image exposure. The development of the electrostatic latent image (that is, the formation of a toner image) is performed with the charged toner attached. 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 (about 300 to 700 V in absolute value).

Below the developing device 4, a paper feed guide 12 for guiding the transfer paper 10 to a transfer area (an area between the transfer device 5 and the photosensitive drum 1) is provided. Above the paper guide 12, that is, directly below the developing device 4, a suction duct 13 is arranged to exhaust the toner scattered from the developing area during development. This prevents contamination inside the apparatus due to the scattered toner.

The transfer device 5 generally includes a transfer charger 5a.
And a separating chargeer 5b, and the transfer paper 1 introduced between the transfer device 5 and the photosensitive drum 1.
0 is charged by the transfer charger 5a to the polarity opposite to that of the toner image, and the toner image is transferred onto the transfer paper 10 by the electrostatic attraction between the charge and the toner image. Also,
At the same time as the transfer of the toner image, the transfer paper 10 is separated from the surface of the photosensitive drum 1 by AC charging by the separation charger 5b. Note that 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 required.

The transfer paper 10 on which the toner image has been transferred is conveyed to a fixing device (not shown), and heat and pressure are applied thereto.
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 toner remaining on the surface of the photosensitive drum 1 is scraped and collected by the cleaning device 6 including a cleaning blade and the like.
The surface charge of the photosensitive drum 1 is removed by light irradiation by the charge removing device 7, and the next image forming process is performed.
The toner collected by the cleaning device 6 is recycled to the developing device 4 along a path indicated by reference numeral 20 using a transport device such as a spiral, and is reused.

In the above-described image forming apparatus, the developing device 4 includes a developing housing 30 having an open upper portion and a side facing the photosensitive drum 1, and a developing device 4 which is attached to and detached from the housing 30 so as to cover the upper portion of the developing housing 30. And a lid 31 freely attached. Development housing 30
A developer transport sleeve (developing sleeve) 32 is disposed so as to face the photosensitive drum 1 and is filled with the developer 25. 33 are formed. As is apparent from FIG. 1, developer stirring paddles 33a and 33b extending coaxially with the developing sleeve 32 are arranged in parallel in the developer stirring and mixing area 33, and these paddles 33a and 33b are arranged in parallel. A feed guide 34 is provided between them. Further, a collected toner storage area 36 defined by a relatively short partition wall 35 is formed adjacent to the developer stirring and mixing area 33, and the collected toner storage area 36 has a pumping paddle 37. Is housed.
As is clear 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 pumping paddle 37.

The developing sleeve 32 has a magnet having a plurality of magnetic poles fixed inside. The developing sleeve 32 conveys the developer 25 in the form of a magnetic brush by rotating the sleeve. , Generally 0.3
It is set to about 1.0 mm. Of course, the developing sleeve 32 may be one that fixes the sleeve and conveys the developer by rotating an internal magnet. Also, a certain distance from the developing sleeve 32 (normally 0.5 to 0.5).
(Approximately 0.9 mm), and the ear cutting blade 38 is attached. That is, the developer 25 pumped up by the developing sleeve 32 is blocked by the spike blades 38 and formed in the developing area (the area between the photosensitive drum 1 and the developing sleeve 32) in the form of a magnetic brush adjusted to a fixed spike length. ), Where the electrostatic latent image is developed.

A power supply 40 is connected to the developing sleeve 32, whereby a developing bias voltage is applied at the time of development (at the time of image formation). That is, when reversal development is performed using positively charged toner, a development bias voltage of about +300 to +700 V is applied to the development sleeve 32,
When using a negatively charged toner, a developing bias voltage of about -300 to -700 V is applied. By applying such a developing bias voltage, the transfer of the charged toner to the electrostatic latent image portion is quickly performed. Further, during non-image formation, for example, when the main switch of the apparatus is turned on, when the shut-off of the apparatus is released, or during the period from the end of the image forming cycle until the rotation of the photosensitive drum 1 is stopped, In order to prevent the charged toner from adhering to the surface of the photosensitive drum 1, a reverse bias voltage (that is, the same absolute value as the developing bias voltage but opposite polarity) is applied by the power supply 40. This prevents wasteful consumption of charged toner and toner contamination on the surface of the photosensitive drum.

The developer agitating paddles 33a and 33b provided in the developer agitating / mixing area 33 are provided for sufficiently frictionally charging 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 a feed guide 34 arranged between these paddles is shown in FIG. Although not shown, a communicating portion is formed at the center or both ends. That is, these developer stirring paddles 33a, 33
b, while the developer 25 is being agitated and fed in the axial direction, the developer 25 is taken in and out at the center or between both ends of the feed guide 33 existing between the two paddles, so that triboelectric charging is efficiently performed. It has become. The developer (toner) 25 triboelectrically charged to a predetermined polarity in this way is pumped up by the developing sleeve 32, and the developer is conveyed to the developing area in the form of a magnetic brush whose spike length is adjusted by the spike blade 38, The development of the electrostatic latent image is performed.

A pumping paddle 37 provided in the collected toner storage area 36 is adjacent to a developer stirring paddle 33b located on a side remote from the developing sleeve 32 in parallel with the paddle 33b via a partition wall 35. ing. That is, the collected toner supplied to the collected toner storage area 36 is pumped up by the pumping paddle 37, and the partition wall 3
5, the developer is supplied to a developer stirring paddle 33b disposed adjacently.

In the present invention, the lid 31 attached to the developing housing 30 is lowered above the collected toner storage area 36, and its inner surface is located near the upper end of the pumping paddle 37. Further, a metal 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 an upper portion of the developing sleeve 32.

According to the present invention, the plate-shaped conductive mesh 50 made of a wire mesh 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. A developing voltage is also applied to the conductive mesh 50 by a power supply 40 for applying a voltage via a rectifier 51 such as a diode. That is, the conductive mesh 50 is maintained at the same polarity potential as the regular charged toner by the developing voltage, and the conductive mesh 50 is arranged near the upper end of the pumping 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 pumping paddle 37, the oppositely charged toner is efficiently captured by the conductive mesh 50. In this case, when the development is performed using the positively charged toner, the conductive mesh 5
Since 0 is maintained at a positive potential, the negatively charged paper powder and the aggregated toner containing the paper powder are also captured by the conductive mesh 50 similarly to the oppositely charged toner (negatively charged toner). It will be. Particularly, the paper powder is caught by the mesh of the conductive mesh 50, so that the capturing is efficiently performed.

As described above, the conductive mesh 50 captures the oppositely charged toner, paper powder, or aggregated toner containing paper powder when the recovered toner is drawn into 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, the mesh opening is desirably 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, when the photosensitive drum 1 is driven and rotated during non-image formation, a reverse bias voltage (a polarity opposite to the developing voltage) is applied by the power supply 40. Therefore,
When the developing bias voltage is directly applied to the conductive mesh 50 by the power supply 40, a reverse bias voltage is applied to the conductive mesh 50, and the captured reversely charged toner and the like are released, and furthermore, the normal polarity is applied. The charged toner is captured. For this reason, it is necessary to apply the developing bias voltage via the rectifier 51.

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

In the present invention, reversely charged toner, paper dust, and the like are captured by the conductive mesh 50 provided on the inner surface of the lid 31 detachably provided on the developing housing 30. Therefore, even if the mesh 50 is clogged, the supply of the developer to the developing sleeve 32 is not impaired, and a constant amount of the developer is always supplied to perform the development. 5
Cleaning and replacement can be performed very easily.

In the present invention, instead of the conductive mesh 50 described above, a metal cover 45 located above the developing sleeve 32 may be used to capture the oppositely charged toner and paper dust. FIG. 2 shows an example using such a metal cover.

That is, as shown in FIG. 2, a rectifier 51 is attached to a metal lid 45 rotatably attached to the lid 31 by the power source 40 in the same manner as the conductive mesh 50 described above.
Is applied through the developing bias voltage. As a result, immediately before the developer 25 is supplied to the developing area, the oppositely charged toner, paper dust, and agglomerated toner including the paper dust are captured on the inner surface of the metal cover 45 and generated by the development with the oppositely charged toner and the like. It is possible to effectively prevent a decrease in image quality. In this example, the reason why the developing bias voltage is applied via the rectifier 51 is to prevent the reverse bias voltage during non-image formation from being applied to the metal cover 45 as in the above-described example. Also in such an image forming apparatus, since the metal cover 45 is rotatably provided, the cleaning 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 area, and the deterioration of image quality due to paper dust and the like can be effectively prevented. Can be prevented.
Further, when the development is performed using the positively charged toner, together with the oppositely charged toner, the paper dust and the aggregated toner including the paper dust can be captured. In particular, when a 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 the drawings]

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

FIG. 2 is a diagram illustrating 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: Recycling route of collected toner 25: Developer 30: Developing housing 31: Lid 32: Developing sleeve 33: Developing agent 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

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shinji Kikuta 1-2-28 Tamazo, Chuo-ku, Osaka-shi Inside Mita Industries Co., Ltd. (72) Inventor Noriyuki Sakata 1-2-28 Tamazo, Chuo-ku, Osaka City F-term (reference) 2H073 AA05 AA07 AA10 BA02 BA11 BA13 BA41 BA45 CA03 2H077 AA37 AB03 AD02 AD06 AD13 AD35 CA11 EA03 GA17

Claims (5)

[Claims] 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. A toner recycling type image forming apparatus for transferring toner onto a transfer paper, collecting toner remaining on the surface of the photosensitive drum after transfer of the toner image by a cleaning device, and recycling the collected toner into the developing device; A developing housing filled with a magnetic developer and having an open upper portion and a side facing the photosensitive drum, and a developer transport sleeve disposed in the developing housing so as to face the photosensitive drum. A lid which is detachably attached so as to cover an upper portion of the developing housing; and a plate-shaped conductive mesh is provided on an 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 developer housing according to claim 1, further comprising: a developer agitating / mixing area having a developer agitating / mixing paddle adjacent to the developer transport sleeve; and a pumping paddle adjacent to the developer agitating / 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 an inner surface of a lid positioned on the collected toner storage area. Image forming apparatus. 3. The inner surface of the lid on the collected toner storage area,
The image forming apparatus according to claim 2, wherein the image forming apparatus is disposed at a position near an upper end of the pumping paddle. 4. The image forming apparatus according to claim 1, wherein a positively charged toner is used as said magnetic developer. 5. A toner image is formed by developing the electrostatic image formed on the surface of the photosensitive drum by reversal development using a magnetic developer filled in a developing device, and forming the toner image into a predetermined image. A collecting toner recycle-type image forming apparatus that transfers the toner onto the transfer paper, collects the toner remaining on the surface of the photosensitive drum after the transfer of the toner image by a cleaning device, and recycles the collected toner into the developing device. The developing device includes a developing housing filled with a magnetic developer and having an open upper portion and a side facing the photosensitive drum, and a developer transporter disposed in the developing housing so as to face the photosensitive drum. A sleeve, and a lid detachably attached so as to cover an upper portion of the developing housing. A metal front cover is rotatably attached to the lid so that a developing bias voltage applied to the developer transport sleeve during development is also applied to the metal front cover via a rectifier. An image forming apparatus characterized by being set.