JP5428536B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device and an image forming apparatus.

    In the developing device, the storage tank is partitioned into a first storage chamber adjacent to the developing roll and a second storage chamber adjacent to the first storage chamber, and between the first storage chamber and the second storage chamber. The developer is moved while stirring (for example, see Patent Document 1).

JP-A-9-204105 (FIG. 5)

  An object of the present invention is to provide a developing device capable of reducing deteriorated toner in a developer, and an image forming apparatus including the developing device.

The invention according to claim 1
An electrostatic image is formed on the surface and adjacent to the image carrier that holds this image. This developer has a potential difference with this image carrier and holds and rotates the developer containing toner. A developing roll for transporting the agent to a developing area facing the image carrier;
Adjacent to the developing roll and extending along the rotation axis of the developing roll, containing the developer inside and supplying the developer to the developing roll, stirring the contained developer on the rotating shaft A first accommodating portion that conveys in a first direction along;
The developer is accommodated in the interior provided with a moving port for the developer to move to and from the first accommodating portion at both ends, which is adjacent to the first accommodating portion and extends side by side with the first accommodating portion. A second storage unit that is supplied with toner and conveys the developer and the toner in a second direction opposite to the first direction while stirring and mixing the developer;
A toner supply unit for supplying toner to the second storage unit through a toner supply port;
A transport body that obtains a developer from the second storage portion downstream of the toner supply port in transport in the second direction, transports the developer while holding the developer on the surface, and returns the developer to the second storage portion. When,
An adsorbent that adsorbs the toner from the developer that is transported by the transport body with the potential difference is provided adjacent to the transport body and has a potential difference.

The invention according to claim 2
The transport body is in a roll shape, and transports the developer to an area facing the adsorbent body by holding and rotating the developer on the surface,
The adsorbent is in the form of a roll and adsorbs the toner from the developer conveyed to the region while rotating.

The invention according to claim 3
The transporting body and the adsorbing body have a potential difference smaller than the potential difference between the developing roll and the image holding body between the transporting body and the adsorbing body, and the relative potential of the adsorbing body with respect to the transporting body. This is characterized in that a potential of the same polarity as that of the relative potential of the image carrier with respect to the developing roll is applied.

The invention according to claim 4
The transporting body and the adsorbing body are provided with a potential in which the polarity of the relative potential of the adsorbing body with respect to the transporting body is opposite to the polarity of the relative potential of the image holding body with respect to the developing roll. It is characterized by that.

The invention according to claim 5
An image carrier that forms an image on the surface and holds the image;
A latent image forming unit that forms an electrostatic latent image on the surface of the image carrier;
A developing unit containing a developer containing the toner, which forms a toner image by attaching toner to the latent image formed on the surface of the image carrier;
The developer is
Adjacent to the image carrier and having a potential difference from the image carrier, the developer is transported to a development area facing the image carrier by rotating the developer while holding the developer on the surface. A developing roll;
Adjacent to the developing roll and extending along the rotation axis of the developing roll, containing the developer inside and supplying the developer to the developing roll, stirring the contained developer on the rotating shaft A first accommodating portion that conveys in a first direction along;
The developer is accommodated in the interior provided with a moving port for the developer to move to and from the first accommodating portion at both ends, which is adjacent to the first accommodating portion and extends side by side with the first accommodating portion. A second storage unit that is supplied with toner and conveys the developer and the toner in a second direction opposite to the first direction while stirring and mixing the developer;
A toner supply unit for supplying toner to the second storage unit through a toner supply port;
A transport body that obtains a developer from the second storage portion downstream of the toner supply port in transport in the second direction, transports the developer while holding the developer on the surface, and returns the developer to the second storage portion. When,
An adsorbent that adsorbs the toner from the developer that is transported by the transporter with the potential difference adjacent to the transporter and that has a potential difference with the transporter is provided. .

The invention according to claim 6
The transporting body and the adsorbing body have a potential difference smaller than the potential difference between the developing roll and the image holding body between the transporting body and the adsorbing body, and the relative potential of the adsorbing body with respect to the transporting body. This is characterized in that a potential of the same polarity as that of the relative potential of the image carrier with respect to the developing roll is applied.

The invention according to claim 7 provides:
The transporting body and the adsorbing body are provided with a potential in which the polarity of the relative potential of the adsorbing body with respect to the transporting body is opposite to the polarity of the relative potential of the image holding body with respect to the developing roll. It is characterized by that.

The invention according to claim 8 provides:
A potential difference applying unit that applies a potential difference between the transporting body and the adsorbing body, wherein a potential difference smaller than the potential difference between the developing roll and the image holding body is generated between the transporting body and the adsorbing body. In addition, a potential difference in which the polarity of the relative potential of the adsorbing body with respect to the transporting body is the same as the polarity of the relative potential of the image holding body with respect to the developing roll, and the polarity of the relative potential of the adsorbing body with respect to the transporting body However, the present invention is characterized in that a potential difference applying unit is provided that switches and applies a potential difference that is opposite in polarity to the polarity of the relative potential of the image carrier with respect to the developing roll.

  According to the developing device of the first aspect, it is possible to reduce deteriorated toner in the developer.

  According to the developing device of the second aspect, the deteriorated toner in the developer can be reduced with a simple configuration.

  According to the developing device of the third aspect, the low-charged toner of the deteriorated toner can be removed at an effective location.

  According to the developing device of the fourth aspect, the reverse polarity toner of the deteriorated toner can be removed at an effective location.

  According to the image forming apparatus of the fifth aspect, it is possible to suppress the deterioration of the image quality and the occurrence of contamination in the apparatus due to the deteriorated toner.

  According to the image forming apparatus of the sixth aspect, it is possible to suppress the occurrence of contamination in the apparatus due to the low-charge toner.

  According to the image forming apparatus of the seventh aspect, it is possible to suppress deterioration in image quality caused by the reverse polarity toner.

  According to the image forming apparatus of the eighth aspect, it is possible to reliably and easily obtain a potential for removing each of the low-charged toner and the reverse polarity toner among the deteriorated toner.

1 is a schematic configuration diagram of a printer. FIG. 2 is a perspective view from the upper surface of the developing device shown in FIG. 1. It is sectional drawing of the developing device shown in FIG. It is a schematic block diagram of a conveyance roll and an adsorption | suction roll. It is a schematic block diagram of the conveyance roll and adsorption | suction roll with which the developing device of 2nd Embodiment is equipped.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a schematic configuration diagram of a printer.

  A printer 1 shown in FIG. 1 includes a photoconductor 10, a charger 11 that applies a charge to the surface of the photoconductor 10, an exposure device 12 that generates exposure light based on image data transmitted from the outside, and the like. A developing device 13 that stores a developer containing toner, a paper cassette 16 that stores recording paper, a paper transport device 17 that pulls out and transports recording paper from the paper cassette 16, and toner that is held on the surface of the photoreceptor 10. A transfer device 14 for transferring the image onto the recording paper conveyed in the direction of arrow B; and a fixing device 15 for fixing the toner image on the recording paper by heating and pressurizing the toner image on the recording paper. Have. The developing device 13 rotates while facing the photoconductor 10 and conveys the developer to a region between the photoconductor 10 and a toner supply unit 130 that supplies toner to the inside of the developing device 13. have. Further, the developing device 13 has a toner concentration sensor (not shown) and a density control unit for keeping the toner concentration in the developer contained in the developing device 13 constant. The density control unit issues a toner supply instruction to the toner supply unit 130 in accordance with the result detected by the toner density sensor. In addition to the toner, the developer contained in the developing unit 13 includes a magnetic carrier that is a charge-providing particle and a magnetic particle that frictionally charges the toner by friction with the toner. The printer 1 is an embodiment of the image forming apparatus of the present invention, and the developing device 13 is the first embodiment of the developing device of the present invention. The photoconductor 10 corresponds to an example of an image carrier referred to in the present invention.

  Here, the flow of the image forming operation in the printer 1 will be briefly described.

  In the printer 1 shown in FIG. 1, a charge is applied by the charger 11 to the surface of the photoconductor 10 rotating in the direction of arrow A, and transmitted from the outside to the surface of the photoconductor 10 to which a predetermined charge has been applied. By exposing the exposure light based on the image data to the exposure device 12, an electrostatic latent image is formed on the surface. The developer accommodated in the developing unit 13 is supplied to the surface of the developing roll 133 and is transported to a region between the developing roll 133 and the photoreceptor 10, although the mechanism will be described later. The electrostatic latent image on the surface of the photoreceptor 10 is developed with the toner. The toner image obtained by this development is transferred by the transfer unit 14 onto the recording paper conveyed in the arrow B direction. Thereafter, the toner image on the recording paper is melted and fixed on the recording paper by a fixing device 15 that heats and pressurizes the toner image. The printer 1 is a monochrome image dedicated machine, but the present invention may be applied to a color image machine.

  FIG. 2 is a perspective view from the upper surface of the developing device shown in FIG.

  FIG. 2 shows a developing device 13 including a developing roll 133, a developer storage tank 132 for storing the developer, and an agitating and conveying member 131 for agitating and conveying the developer.

  FIG. 2 shows a state in which a transport roll 134 and an adsorption roll 135 are provided to remove deteriorated toner from the developer stored in the developer storage tank 132, as will be described in detail later. Has been.

  The transport roll 134 rotates while holding the developer contained in the developer container 132 on the surface in a state where a part thereof is exposed to the outside from the developer container 132. Further, the suction roll 135 is disposed to face a portion of the transport roll 134 exposed to the outside from the developer storage tank 132, and sucks the toner deteriorated from the developer held by the transport roll 134 while rotating it. To do. The transport roll 134 and the suction roll 135 are arranged on the downstream side of the toner supply port 132c in the direction in which the developer is transported. The reason for this will be described later.

  The developer storage tank 132 has a first storage chamber 132a adjacent to the development roll 133 and a second storage chamber adjacent to the first storage chamber 132a by a wall 1321 extending in parallel with the development roll 133. 132b. In each of the first storage chamber 132a and the second storage chamber 132b, one agitation transport member 131 is provided. Specifically, the agitation transport member 131 includes a spiral fin around the rod. It has a provided structure. As the agitating and conveying member 131 provided in each of the first accommodation chamber 132a and the second accommodation chamber 132b rotates in the opposite directions, the developer accommodated in the developer accommodating tank 132 is agitated around the wall 1321. Cycle counterclockwise. Inside the developer storage tank 132, the toner and the magnetic carrier are agitated by the agitating and conveying member 131, so that the toner is negatively charged and the magnetic carrier is positively charged. For this reason, the negatively charged toner adheres electrostatically to the magnetic carrier. As a result, the toner and the magnetic carrier are naturally integrated inside the developer storage tank 132.

  As shown in FIG. 2, the developer storage tank 132 is provided with a toner supply port 132 c for supplying new toner.

  The transport roll 134 shown in FIG. 2 rotates to the developer accommodating tank 132 so that the surface is partially exposed from an opening 132d (see FIG. 3B) provided in a part of the developer accommodating tank 132. The axis is held.

  As shown in FIG. 2, the suction roll 135 disposed opposite the transport roll 134 is covered with a toner collection box 136 that is detachable from the developer storage tank 132, and the suction roll 135 is suctioned. The rotating shaft of the roll 135 is held in the toner recovery box 136.

  FIG. 3 is a cross-sectional view of the developing device shown in FIG.

  The developing roll 133 shown in FIG. 3 includes a cylindrical member 1331 that rotates in the direction of arrow C, and a permanent magnet roll 1332 that is fixed inside the cylindrical member 1331 independently of the cylindrical member 1331. The permanent magnet roll 1332 has a plurality of magnetic poles arranged in the circumferential direction of the cylindrical member 1331 and has a magnetic force distribution that regulates adsorption and release of the developer.

  The rotating cylindrical member 1331 is supplied with the developer while passing through the developer storage tank due to the magnetic distribution of the permanent magnet roll 1332 inside, and the supplied developer is formed between the photosensitive member 10 and the developer. It is conveyed to the developed area 130a.

  In this printer 1, the entire surface of the photoreceptor 10 is temporarily charged to −700 V by the charger 11, and the potential of the portion where the electrostatic latent image is formed by exposure by the exposure device 12 is about −150 V.

  On the other hand, a voltage is applied to the developing roll 133 of the developing device 13 at −500V. For this reason, the toner charged in the negative polarity in the developer storage tank 132 is caused by an electric field (potential difference is 350 V) in the developing region 130a from the electrostatic latent image portion of the photoreceptor 10 toward the developing roll 133. It overcomes the electrostatic attraction between the magnetic carrier and adheres to the electrostatic latent image side. At this time, the magnetic carrier remains on the developing roll 133 while being attracted to the surface of the cylindrical member 1331 of the developing roll 133 by a magnetic force, and is collected into the developer containing tank 132.

  Part (a) of FIG. 3 shows a case where the developing device 13 is viewed from the AA cross section shown in FIG. 2 as an arrow. Here, new toner is supplied to the second storage chamber 132b. A toner supply port 132c provided for this purpose is also shown.

  Part (b) of FIG. 3 includes a transport roll 134 partially exposed from the opening 132 d provided on the second storage chamber 132 b side of the developer storage tank 132, and a suction roll 135 adjacent to the transport roll 134. Is shown. Further, here, a state in which the deteriorated toner adsorbed by the adsorbing roll 135 is scraped off by the end 1361 of the toner recovery box 136 is shown.

  Similarly to the developing roller 133, the transport roller 134 includes a cylindrical member 1341 that rotates in the direction of arrow D, and a plurality of conveying rollers 134 that are fixed inside the cylindrical member 1341 independently of the cylindrical member 1341 in the circumferential direction of the cylindrical member 1341. And a permanent magnet roll 1342 having a predetermined magnetic distribution defining the adsorption and release of the developer. The suction roll 135 is a cylindrical member made of aluminum or stainless steel.

  Here, in this printer 1, in a situation where image formation with low image density continues for a long time and new toner is not supplied much, it is applied to the toner surface by repeated friction between the existing toner and the magnetic carrier. The charge control member for controlling the chargeability of the toner is buried or unevenly distributed on the surface of the toner, so that the chargeability of the toner is deteriorated. Charge distribution is obtained. When such low image density image formation is continuously performed and then high image density image formation is performed, a large amount of new toner is supplied to the second storage chamber 132b of the developer storage tank 132 through the toner supply port 132c. To be supplied. As a result, the charge of the toner having a deteriorated chargeability inside the developer storage tank 132 rapidly moves to the newly supplied toner, and is newly supplied inside the developer storage tank 132. In addition to the transfer of charge to the toner, the charge amount rises slowly due to friction with the magnetic carrier due to deterioration, the reverse-polarity toner that has been reverse-polarized due to the transfer of charge, and the newly charged The toner is held on the developing roll 133. For this reason, the low charge toner whose electrostatic connection with the magnetic carrier is weakened due to insufficient charge amount is scattered away from the magnetic carrier without adhering to the electrostatic latent image, The reverse polarity toner that has turned to the reverse polarity adheres to a so-called background region, which is a portion other than the portion where the electrostatic latent image formed on the surface of the photoreceptor 10 is formed.

  Therefore, in the printer 1 of the present embodiment, the deteriorated toner is removed using the transport roll 134 and the suction roll 135 as described below, thereby partially reducing the image density due to the low-charged toner, contamination in the apparatus, Degradation of image quality due to reverse polarity toner is suppressed.

  Hereinafter, a mechanism for removing the deteriorated toner from the developer stored in the developer storage tank 132 by the transport roll 134 and the suction roll 135 will be described.

  FIG. 4 is a schematic configuration diagram of the transport roll and the suction roll.

  FIG. 4 shows a state in which the transport roll 134 is connected to a voltage controller 137 that controls the voltage applied to the transport roll 134 and the suction roll 135 is grounded.

  A voltage is applied to the transport roll 134 in the same manner as the developing roll 133, and the developer roll is held by the same mechanism as the developing roll 133 holds the developer and is transported to an area between the suction roll 135 and the transport roll 134. To do. For the suction roll 135 that is grounded, a low-charge toner or a reverse polarity toner that is a deteriorated toner in the developer conveyed by the conveyance roll 134 is selected according to the polarity of the voltage applied from the voltage controller 137 to the conveyance roll 134. Adsorbs.

  The voltage controller 137 has a minus variable power source 1371 that can adjust the voltage applied to the transport roll 134 between −10V and −300V, and a plus variable power source 1372 that can adjust the applied voltage between + 10V and + 300V. have.

  FIG. 4 shows a state in which the transport roll 134 is connected to the terminal A of the minus variable power source 1371 of the voltage controller 137. In this case, since a voltage between −10 V and −300 V is applied to the transport roll 134, the transport roll 134 is directed to the transport roll 134 from the suction roll 135 with respect to the grounded suction roll 135, and Further, an electric field (potential difference is a maximum of 300 V) that is weaker than an electric field (potential difference is 350 V) generated between the electrostatic latent image on the surface of the photoconductor 10 and the developing roll 133 is generated. As a result, the low-charge toner having a small amount of charge but having a negative polarity is directed to the suction roll 135.

  When an electric field weaker than the electric field generated between the electrostatic latent image on the surface of the photoconductor 10 and the developing roll 133 is generated between the suction roll 135 and the transport roll 134, the low-charge toner is transferred to the transport roll 134. Since the electrostatic connection with the magnetic carrier magnetically held on the surface of the toner is weak and can be separated from the magnetic carrier even if the electric field is weak, the low-charge toner in the developer is adsorbed by the adsorption roll 135 be able to. If the electric field strength between the suction roll 135 and the transporting roll 134 is as strong as the electric field strength between the electrostatic latent image on the surface of the photoconductor 10 and the developing roll 133, high charge that is not deteriorated is obtained. In order to selectively adsorb the low-charged toner from the developer, the electric field strength between the adsorbing roll 135 and the conveying roll 134 is electrostatic on the surface of the photoreceptor 10. The electric field generated between the latent image and the developing roll 133 is weakened.

  On the other hand, although illustration is omitted, when the transport roll 134 is connected to the terminal B of the plus variable power source 1372 of the voltage controller 137, a voltage between +10 V and +300 V is applied to the transport roll 134. An electric field in the direction from the transport roll 134 toward the suction roll 135 is generated between the suction roll 135 and the ground fault. As a result, the reverse polarity toner whose polarity has changed to the positive side because it has deteriorated after the charge has moved moves toward the suction roll 135. The voltage controller 137 switches between the minus variable power source 1371 and the plus variable power source 1372 and the applied voltage value at each power source is an optical sensor for detecting the degree of contamination due to toner scattering in the printer 1 and an image background portion. Is automatically controlled according to the detection result of the optical sensor for detecting the dirt of the ink.

  As described above, in this printer 1, since the toner is newly deteriorated on the downstream side of the toner supply port 132 in the direction in which the developer is conveyed, the charge is moved and the charge is reduced. The removed toner is removed from the developer. Further, the direction of the electric field between the transport roll 134 and the suction roll 135 is deteriorated by making the direction of the electrostatic latent image on the surface of the photoconductor 10 and the direction of the electric field between the developing roll 133 reverse. For this reason, the reverse polarity toner which has been reversed by charge movement is removed from the developer.

  Next, a second embodiment of the developing device of the present invention will be described.

  The difference between the developing device of the second embodiment and the developing device 13 of the first embodiment is that, in the first embodiment, the voltage controller 137 is connected to the transport roll 134 and the suction roll 135 is grounded. In the second embodiment, the conveyance roll 134 is grounded, and the suction roll 135 is connected to the voltage controller 137. Hereinafter, this difference will be described.

  FIG. 5 is a schematic configuration diagram of the transport roll and the suction roll provided in the developing device of the second embodiment.

  FIG. 5 shows a state in which the suction roll 135 is connected to a voltage controller 137 that controls a voltage applied to the suction roll 135 and the transport roll 134 is grounded.

  5 shows a state in which the suction roll 135 is connected to the terminal A of the minus variable power source 1371 of the voltage controller 137. In this case, since a voltage between −10 V and −300 V is applied to the suction roll 135, an electric field in the direction from the transport roll 134 toward the suction roll 135 is generated between the suction roll 135 and the grounded transport roll 134. Occur. As a result, the reverse polarity toner whose polarity has changed to the positive side because it has deteriorated after the charge has moved moves toward the suction roll 135.

  On the other hand, although illustration is omitted, when the suction roll 135 is connected to the terminal B of the plus variable power source 1372 of the voltage controller 137, a voltage between + 10V and + 300V is applied to the suction roll 135. The electric field generated between the electrostatic roll image on the surface of the photosensitive member 10 and the developing roll 133 in the direction from the suction roll 135 to the conveyance roll 134 with the conveyance roll 134 that is grounded. An electric field (potential difference is 300 V at maximum) is generated. As a result, the low-charge toner having a small amount of charge but having a negative polarity is directed to the suction roll 135.

  As described above, even when the developing device of the second embodiment is provided, it is deteriorated by the toner newly supplied downstream of the toner supply port 132 in the direction in which the developer is conveyed. The toner that has become low-charged due to the movement of the charge is removed from the developer. Further, the direction of the electric field between the transport roll 134 and the suction roll 135 is deteriorated by making the direction of the electrostatic latent image on the surface of the photoconductor 10 and the direction of the electric field between the developing roll 133 reverse. For this reason, the reverse polarity toner which has been reversed by charge movement is removed from the developer.

  In the above embodiment, a printer has been described as an example of the image forming apparatus of the present invention. However, this may be a copying machine.

  Further, in the above embodiment, a potential difference smaller than the potential difference between the developing roll and the image holding member is generated between the transporting body and the adsorbing body, and the polarity of the relative potential of the adsorbing body with respect to the transporting body is the developing roll. By applying a potential that is the same as the polarity of the relative potential of the image carrier relative to the toner, the low-charged toner is removed from the developer, and the relative potential polarity of the adsorbent relative to the transporting body is such that the image retention on the developing roll Although an example in which the reverse polarity toner is removed from the developer by applying a potential that is opposite to the polarity of the relative potential of the body has been described, the present invention is provided between the carrier and the adsorbent. In addition, a potential difference that is greater than the potential difference between the developing roll and the image holding member is generated, and the polarity of the relative potential of the adsorbing member with respect to the transporting member is the same as the polarity of the relative potential of the image holding member with respect to the developing roller. Granted By being, over-charged toner is deteriorated toner may be one that is removed from the developer.

DESCRIPTION OF SYMBOLS 1 Printer 10 Photoconductor 11 Charger 12 Exposure device 13 Developer 131 Stirring conveyance member 132 Developer storage tank 133 Development roll 134 Transport roll 135 Adsorption roll 136 Toner collection box 137 Voltage controller 1371 Negative variable power supply 1372 Plus variable power supply 14 Transfer 15 Fixing device 16 Paper cassette 17 Paper transport device

Claims (2)

An electrostatic image is formed on the surface and adjacent to the image carrier that holds the image. The developer has a potential difference with the image carrier and holds and rotates the developer containing toner. A developing roll for transporting the agent to a developing area facing the image carrier;
Adjacent to the developing roll and extending along the rotating shaft of the developing roll, containing the developer inside and supplying the developer to the developing roll, stirring the contained developer on the rotating shaft A first accommodating portion that conveys in a first direction along;
The developer is accommodated in the interior, which is provided adjacent to the first accommodating portion and extends in parallel with the first accommodating portion, at both ends provided with moving ports for moving the developer between the first accommodating portion and the first accommodating portion. A second storage unit that is supplied with toner and conveys the developer and the toner in a second direction opposite to the first direction while stirring and mixing the developer;
A toner supply unit that supplies toner to the second storage unit through a toner supply port;
A transport body that obtains a developer from the second storage portion downstream of the toner supply port in transport in the second direction, transports the developer while holding the developer on the surface, and returns the developer to the second storage portion When,
An adsorbent that adsorbs the toner from the developer that is transported by the transport body at the potential difference adjacent to the transport body and has a potential difference with the transport body;
The transporting body and the adsorbing body have a potential difference larger than the potential difference between the developing roll and the image holding body between the transporting body and the adsorbing body, and the relative potential of the adsorbing body with respect to the transporting body. The developing device is characterized in that a potential of which is the same polarity as that of the relative potential of the image carrier with respect to the developing roll is provided. An image carrier that forms an image on the surface and holds the image;
A latent image forming unit that forms an electrostatic latent image on the surface of the image carrier;
A developing unit containing a developer containing the toner, which forms a toner image by attaching toner to a latent image formed on the surface of the image carrier;
The developer is
Adjacent to the image carrier and having a potential difference with the image carrier, the developer is held on the surface and rotated to convey the developer to a development area facing the image carrier. A developing roll;
Adjacent to the developing roll and extending along the rotating shaft of the developing roll, containing the developer inside and supplying the developer to the developing roll, stirring the contained developer on the rotating shaft A first accommodating portion that conveys in a first direction along;
The developer is accommodated in the interior, which is provided adjacent to the first accommodating portion and extends in parallel with the first accommodating portion, at both ends provided with moving ports for moving the developer between the first accommodating portion and the first accommodating portion. A second storage unit that is supplied with toner and conveys the developer and the toner in a second direction opposite to the first direction while stirring and mixing the developer;
A toner supply unit that supplies toner to the second storage unit through a toner supply port;
A transport body that obtains a developer from the second storage portion downstream of the toner supply port in transport in the second direction, transports the developer while holding the developer on the surface, and returns the developer to the second storage portion When,
Adjacent to the transport body, the transport body has a potential difference, and is provided with an adsorbing body that adsorbs the toner from the developer being transported by the transport body by the potential difference,
The transporting body and the adsorbing body have a potential difference larger than the potential difference between the developing roll and the image holding body between the transporting body and the adsorbing body, and the relative potential of the adsorbing body with respect to the transporting body. The image forming apparatus is characterized in that a polarity of the same is given to a polarity that is the same as the polarity of the relative potential of the image carrier relative to the developing roll .

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