JP2011033934A - Developing device and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device which lightens stress on developer in the developing device, so that wear of the developer is suppressed and a stable-quality image is obtained, and to provide an image forming apparatus using the same. <P>SOLUTION: The developing device 2 includes a developing tank 111, a developing roller 114 and a doctor blade 116 regulating a supply amount of developer by the developing roller 114. The developing roller 114 includes a developing sleeve 119 and a magnet roller 120 having a plurality of magnetic poles. The magnet roller 120 includes a first magnetic pole 120a constituted by using an electromagnet at a developer drawing-up position, and a second magnetic pole 120b provided adjacent to the first magnetic pole 120a on a downstream side in a rotating direction of the developing sleeve 119 and having a polarity different from the polarity of the first magnetic pole 120a obtained when an image is formed. The first magnetic pole 120a is set so that its polarity obtained when an image is not formed may be the same as the polarity of the second magnetic pole 120b. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a developing device and an image forming apparatus using the same, and more particularly to an image forming apparatus such as an electrostatic copying machine, a laser printer, and a facsimile machine that forms an image using toner by an electrophotographic method. The present invention relates to a developing device using a two-component developer containing a magnetic carrier and an image forming apparatus using the developing device.

  2. Description of the Related Art Conventionally, electrophotographic image forming apparatuses such as copying machines, printers, and facsimiles are known. An electrophotographic image forming apparatus forms an electrostatic latent image on the surface of a photosensitive drum (toner image carrier), and develops the electrostatic latent image by supplying toner to the photosensitive drum by a developing device. The toner image formed on the photosensitive drum by development is transferred to a sheet such as paper, and the toner image is fixed on the sheet by a fixing device.

  2. Description of the Related Art In recent years, two-component developers (hereinafter simply referred to as “developers”) that are excellent in toner charge stability are often used in image forming apparatuses that support full color and high image quality.

  This developer is composed of toner and carrier, and the toner and the carrier are rubbed by stirring them in the developing device, and a properly charged toner is obtained by this friction.

  In the developing device, the charged toner is supplied to the surface of a developer carrying member, for example, a developing roller. The toner supplied to the developing roller moves to an electrostatic latent image formed on the photosensitive drum by an electrostatic attraction force. As a result, a toner image based on the electrostatic latent image is formed on the photosensitive drum.

  Furthermore, recently, there has been a demand for higher image quality and energy saving in image forming apparatuses, and a small particle size carrier of 30 to 50 μm and a small particle size toner having a low softening temperature of 5 to 7 μm have been used. ing. Such a developer has a problem that it easily aggregates due to heat and stress.

  Therefore, as a method for relieving the stress applied to the developer in the developing device, for example, a polarity opposite to the pumping magnetic pole is provided at a position opposite to the pumping magnetic pole that pumps up the developer provided in the developing roller. There has been proposed an electromagnet that forms a magnetic pole and reduces the stress applied to the developer by reducing the current amount of the electromagnet during non-image formation (see Patent Document 1).

JP 2006-243113 A

  However, the method of Patent Document 1 has a problem that the developer is difficult to flow because the developer is adsorbed to the electromagnet. In addition, there is a problem in that the developer conveyed by the developing roller generates heat due to the magnetic lines formed between the electromagnet and the pumping magnetic pole, and the fluidity of the developer is extremely reduced.

  The present invention has been made in view of the above-described conventional problems, and can reduce stress applied to the developer in the developing device, suppress the wear of the developer, and can provide a stable image quality image. And an image forming apparatus using the same.

  The developing device and the image forming apparatus using the same according to the present invention for solving the above-described problems are as follows.

  The present invention relates to a developing tank that contains a developer containing toner and a carrier, a developing roller that pumps up the developer in the developing tank and supplies the toner contained in the developer to a photosensitive drum, and the developing roller And a regulating member that regulates the supply amount of the developer conveyed by the cylinder, wherein the developing roller is provided so as to be rotatable with respect to the developing tank, and is non-rotating with respect to the developing tank. In a developing device including a magnet roller having a plurality of magnetic poles provided, as the configuration of the magnet roller, a first magnetic pole configured using an electromagnet at a position where the developer is pumped, and a developing sleeve rotation of the first magnetic pole A second magnetic pole provided adjacent to the downstream side in the direction and having a polarity different from that of the first magnetic pole at the time of image formation. Smaller than the magnetic flux density takes flux density at the time of image formation, or, is characterized in that the polarity in the non-image-forming period is the same as the polarity of the second magnetic pole.

  In the present invention, it is preferable that the first magnetic pole is configured using a permanent magnet in addition to an electromagnet, and the polarity of the permanent magnet is different from the polarity of the second magnetic pole during image formation.

  In the present invention, it is preferable that the first magnetic pole is configured by a so-called sandwich structure in which both sides of the permanent magnet are sandwiched between the electromagnets.

  The present invention also provides a photosensitive drum on which an electrostatic latent image is formed, a charging device that charges the surface of the photosensitive drum, an exposure device that forms an electrostatic latent image on the surface of the photosensitive drum, A developing device for supplying toner to the electrostatic latent image on the surface of the photosensitive drum to form a toner image, a transfer device for transferring the toner image to a recording medium, and fixing the transferred toner image to the recording medium An image forming apparatus comprising a fixing device and forming an image using toner by electrophotography, wherein the developing device according to any one of claims 1 to 3 is used as the developing device. It is a feature.

  According to the present invention, a developing tank that stores a developer containing toner and a carrier, a developing roller that pumps up the developer in the developing tank and supplies the toner contained in the developer to the photosensitive drum, A regulating member that regulates the supply amount of the developer conveyed by the developing roller, and the developing roller is provided with a cylindrical developing sleeve that is rotatably provided with respect to the developing tank, and a non-developing element with respect to the developing tank. In a developing device including a magnet roller having a plurality of magnetic poles provided for rotation, the magnet roller is configured such that a first magnetic pole configured using an electromagnet at a position where the developer is pumped, and development of the first magnetic pole A second magnetic pole provided adjacent to the downstream side in the sleeve rotation direction and having a polarity different from the polarity of the first magnetic pole during image formation, wherein the first magnetic pole is a non-image type The magnetic flux density at the time is smaller than the magnetic flux density at the time of image formation, or the polarity at the time of non-image formation is the same as the polarity of the second magnetic pole, so that the repulsive magnetic field (the magnetic field lines between the first magnetic pole and the second magnetic pole) Is released from the developing roller), and the developer is separated from the developing roller, whereby the developer conveyed to the regulating member can be reduced. As a result, the stress received when the developer is regulated by the regulating member can be alleviated and the developer can be prevented from being worn, so that a stable image can be obtained.

  Further, according to the present invention, the first magnetic pole is configured using a permanent magnet in addition to an electromagnet, and the polarity of the permanent magnet is different from the polarity of the second magnetic pole at the time of image formation. At the time of formation, since the magnetic force of the permanent magnet can be used supplementarily, the power consumption of the electromagnet can be reduced.

  According to the present invention, the electromagnet is different from the permanent magnet during non-image formation by configuring the first magnetic pole so as to sandwich both sides of the permanent magnet with the electromagnet. By generating a magnetic field, it is possible to effectively block magnetic lines of force from the permanent magnet toward the second magnetic pole.

  The present invention also provides a photosensitive drum on which an electrostatic latent image is formed, a charging device that charges the surface of the photosensitive drum, an exposure device that forms an electrostatic latent image on the surface of the photosensitive drum, A developing device for supplying toner to the electrostatic latent image on the surface of the photosensitive drum to form a toner image, a transfer device for transferring the toner image to a recording medium, and fixing the transferred toner image to the recording medium An image forming apparatus comprising a fixing device and forming an image using toner by electrophotography, wherein the developing device according to claim 1 is used as the developing device. Since the stress received by the developer conveyed by the developing roller constituting the developing device can be alleviated and the wear of the developer can be suppressed, a stable image can be formed over a long period of time.

1 is an explanatory diagram illustrating an overall configuration of an image forming apparatus in which a developing device according to a first embodiment of the present invention is used. FIG. 2 is a cross-sectional view illustrating a schematic configuration of a toner replenishing device constituting the image forming apparatus. It is CC sectional view taken on the line of FIG. FIG. 2 is a cross-sectional view illustrating a configuration of a developing device that constitutes the image forming apparatus. It is an AA cross-sectional arrow view of FIG. It is a BB cross-sectional arrow view of FIG. It is explanatory drawing which shows the state at the time of electricity supply (at the time of normal image formation) of the electromagnet (1st magnetic pole) which comprises the developing roller in the said developing device. It is explanatory drawing which shows the state at the time of the non-energization (at the time of non-image formation) of the said electromagnet (1st magnetic pole). It is sectional drawing which shows the structure of the developing device which concerns on 2nd Embodiment of this invention.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an example of an embodiment for carrying out the invention, and is an explanatory view showing the overall configuration of an image forming apparatus using a developing device according to the first embodiment of the present invention.

  In the first embodiment, as shown in FIG. 1, a photosensitive drum 3 on which an electrostatic latent image is formed, a charger (charging device) 5 that charges the surface of the photosensitive drum 3, and the photosensitive drum 3. An exposure unit (exposure device) 1 for forming an electrostatic latent image on the surface, a developing device 2 for supplying toner to the electrostatic latent image on the surface of the photosensitive drum 3 to form a toner image, and a toner for the developing device 2 A toner replenishing device 22 for replenishing, an intermediate transfer belt unit (transfer device) 8 for transferring the toner image on the surface of the photosensitive drum 3 to a recording medium, and a fixing unit (fixing device) 12 for fixing the toner image on the recording medium. In addition, in the image forming apparatus 100 that forms an image using toner by electrophotography, the configuration of the developing device according to the present invention is adopted as the developing device 2.

  The image forming apparatus 100 forms a multicolor or single color image on a predetermined sheet (recording paper, recording medium) according to image data transmitted from the outside. A scanner or the like may be provided above the image forming apparatus 100.

First, the overall configuration of the image forming apparatus 100 will be described.
As shown in FIG. 1, the image forming apparatus 100 handles image data for each color component of black (K), cyan (C), magenta (M), and yellow (Y). An image and a yellow image are formed, and a color image is formed by superimposing the images of the respective color components.

  Accordingly, in the image forming apparatus 100, as shown in FIG. 1, the developing device 2 (2a, 2b, 2c, 2d) and the photosensitive drum 3 (3a, 3b, 3c) are formed so that images of the respective color components are formed. , 3d), four chargers 5 (5a, 5b, 5c, 5d) and four cleaner units 4 (4a, 4b, 4c, 4d). In other words, four image forming stations (image forming units) each including the developing device 2, the photosensitive drum 3, the charger 5, and the cleaner unit 4 are provided.

  The symbols a to d indicate that a is a member for forming a black image, b is a member for forming a cyan image, c is a member for forming a magenta image, and d is a member for forming a yellow image. It is a thing. Further, the image forming apparatus 100 includes an exposure unit 1, a fixing unit 12, a sheet conveyance path S, a paper feed tray 10, and a paper discharge tray 15.

The charger 5 uniformly charges the surface of the photosensitive drum 3 to a predetermined potential.
As the charger 5, in addition to the contact roller type charger shown in FIG. 1, a contact brush type charger or a non-contact charger type charger may be used.

  As shown in FIG. 1, the exposure unit 1 is a laser scanning unit (LSU) including a laser irradiation unit and a reflection mirror. However, in addition to the laser scanning unit, the exposure unit 1 may be an EL (electroluminescence) in which light emitting elements are arranged in an array or an LED writing head. The exposure unit 1 exposes the charged photosensitive drum 3 according to the input image data, thereby forming an electrostatic latent image corresponding to the image data on the surface of the photosensitive drum 3.

  The developing device 2 visualizes (develops) the electrostatic latent image formed on the photosensitive drum 3 with one of K, C, M, and Y toners. Above the developing device 2 (2a, 2b, 2c, 2d), there are a toner transfer mechanism 102 (102a, 102b, 102c, 102d), a toner supply device 22 (22a, 22b, 22c, 22d), a developing tank (developer). (Container) 111 (111a, 111b, 111c, 111d).

  The toner replenishing device 22 is disposed above the developing tank 111 and stores unused toner (powdered toner). The toner is supplied from the toner supply device 22 to the developing tank 111 via the toner transfer mechanism 102.

  The cleaner unit 4 removes and collects the toner remaining on the surface of the photosensitive drum 3 after the development and image transfer processes.

  An intermediate transfer belt unit 8 is disposed above the photosensitive drum 3. The intermediate transfer belt unit 8 includes an intermediate transfer roller 6 (6a, 6b, 6c, 6d), an intermediate transfer belt 7, an intermediate transfer belt driving roller 71, an intermediate transfer belt driven roller 72, an intermediate transfer belt tension mechanism 73, and an intermediate transfer. A belt cleaning unit 9 is provided.

  The intermediate transfer belt 6, the intermediate transfer belt drive roller 71, the intermediate transfer belt driven roller 72, and the intermediate transfer belt tension mechanism 73 stretch the intermediate transfer belt 7 and rotationally drive the intermediate transfer belt 7 in the direction of arrow B in FIG. It is something to be made.

  The intermediate transfer roller 6 is rotatably supported by an intermediate transfer roller mounting portion in the intermediate transfer belt tension mechanism 73 of the intermediate transfer belt unit 8. A transfer bias for transferring the toner image on the photosensitive drum 3 onto the intermediate transfer belt 7 is applied to the intermediate transfer roller 6.

  The intermediate transfer belt 7 is provided so as to be in contact with each photosensitive drum 3. A color toner image (multicolor toner image) is formed on the intermediate transfer belt 7 by sequentially superimposing and transferring the toner images of the respective color components formed on the photosensitive drum 3. The intermediate transfer belt 7 is formed in an endless shape using a film having a thickness of, for example, about 100 μm to 150 μm.

  Transfer of the toner image from the photosensitive drum 3 to the intermediate transfer belt 7 is performed by the intermediate transfer roller 6 in contact with the back side of the intermediate transfer belt 7. A high voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the intermediate transfer roller 6 in order to transfer the toner image.

  The intermediate transfer roller 6 is formed based on a metal (for example, stainless steel) shaft having a diameter of, for example, 8 to 10 mm, and the surface is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). With this conductive elastic material, the intermediate transfer roller 6 can uniformly apply a high voltage to the intermediate transfer belt 7. In this embodiment, a roller-shaped transfer electrode (intermediate transfer roller 6) is used as the transfer electrode, but a brush or the like can also be used.

  As described above, the electrostatic latent images on the respective photosensitive drums 3 are visualized with toners corresponding to the respective color components to become toner images, and these toner images are superimposed and laminated on the intermediate transfer belt 7. As described above, the stacked toner images are moved to a contact position (transfer portion) between the conveyed paper and the intermediate transfer belt 7 by the rotation of the intermediate transfer belt 7, and the transfer roller disposed at this position is moved. 11 is transferred onto the paper. In this case, the intermediate transfer belt 7 and the transfer roller 11 are pressed against each other at a predetermined nip, and a voltage for transferring the toner image onto the sheet is applied to the transfer roller 11. This voltage is a high voltage having a polarity (+) opposite to the charging polarity (−) of the toner.

  In order to obtain the nip constantly, either the transfer roller 11 or the intermediate transfer belt drive roller 71 is made of a hard material such as metal, and the other is a soft material such as an elastic roller (elastic rubber roller or foamable resin roller). Etc.).

  The toner adhering to the intermediate transfer belt 7 due to the contact between the intermediate transfer belt 7 and the photosensitive drum 3 and the toner image remaining on the intermediate transfer belt 7 without being transferred when the toner image is transferred from the intermediate transfer belt 7 to the sheet. The toner is removed and collected by the intermediate transfer belt cleaning unit 9 because it causes toner color mixing in the next step.

  The intermediate transfer belt cleaning unit 9 is provided with a cleaning blade (cleaning member) that contacts the intermediate transfer belt 7. The portion of the intermediate transfer belt 7 that is in contact with the cleaning blade is supported by the intermediate transfer belt driven roller 72 from the back side.

  The paper feed tray 10 is for storing sheets (for example, recording paper) used for image formation, and is provided below the image forming unit and the exposure unit 1. On the other hand, a paper discharge tray 15 provided in the upper part of the image forming apparatus 100 is for placing printed sheets face down.

  Further, the image forming apparatus 100 is provided with a sheet conveyance path S for guiding the sheet of the paper feed tray 10 and the sheet of the manual feed tray 20 to the paper discharge tray 15 via the transfer unit and the fixing unit 12. . The transfer unit is located between the intermediate transfer belt driving roller 71 and the transfer roller 11.

  Further, a pickup roller 16 (16a, 16b), a registration roller 14, a transfer unit, a fixing unit 12, a conveyance roller 25 (25a to 25h), and the like are arranged in the sheet conveyance path S.

  The conveyance rollers 25 are small rollers for promoting and assisting conveyance of the sheet, and a plurality of conveyance rollers 25 are provided along the sheet conveyance path S. The pickup roller 16 a is a pull-in roller that is provided at the end of the paper feed tray 10 and supplies sheets one by one from the paper feed tray 10 to the sheet conveyance path S. The pickup roller 16 b is a drawing roller that is provided near the manual feed tray 20 and supplies sheets from the manual feed tray 20 to the sheet conveyance path S one by one. The registration roller 14 temporarily holds the sheet conveyed in the sheet conveyance path S, and conveys the sheet to the transfer unit at a timing when the leading edge of the toner image on the intermediate transfer belt 7 and the leading edge of the sheet are aligned.

  The fixing unit 12 includes a heat roller 81, a pressure roller 82, and the like. The heat roller 81 and the pressure roller 82 rotate with the sheet interposed therebetween. The heat roller 81 is controlled by a control unit (not shown) so as to have a predetermined fixing temperature. This control unit controls the temperature of the heat roller 81 based on a detection signal from a temperature detector (not shown).

  The heat roller 81 heat-presses the sheet together with the pressure roller 82 to melt, mix, and press the color toner images transferred to the sheet, and heat-fix the sheet. The sheet on which the multicolor toner image (each color toner image) is fixed is conveyed to the reverse sheet discharge path of the sheet conveyance path S by the plurality of conveyance rollers 25 and is reversed (the multicolor toner image is on the lower side). Are discharged onto the paper discharge tray 15.

Next, the sheet conveying operation by the sheet conveying path S will be described.
As shown in FIG. 1, the image forming apparatus 100 is provided with a paper feed tray 10 that stores sheets in advance and a manual feed tray 20 that is used when printing a small number of sheets as described above. Pickup rollers 16 (16a, 16b) are disposed on both trays, and the pickup rollers 16 supply sheets one by one to the sheet conveyance path S.

  In the case of single-sided printing, the sheet conveyed from the sheet feeding tray 10 is conveyed to the registration roller 14 by the conveyance roller 25a in the sheet conveyance path S, and is stacked on the leading edge of the sheet and the intermediate transfer belt 7 by the registration roller 14. Then, the toner image is conveyed to a transfer portion (contact position between the transfer roller 11 and the intermediate transfer belt 7) at a timing when the leading edge of the toner image is aligned. In the transfer portion, a toner image is transferred onto the sheet, and this toner image is fixed on the sheet by the fixing unit 12. Thereafter, the sheet is discharged onto the discharge tray 15 from the discharge roller 25c via the conveyance roller 25b.

  Further, the sheet conveyed from the manual feed tray 20 is conveyed to the registration roller 14 by a plurality of conveying rollers 25 (25f, 25e, 25d). Subsequent sheet conveyance operations are discharged to the sheet discharge tray 15 through a process similar to that for the sheets supplied from the sheet feed tray 10 described above.

  On the other hand, in the case of double-sided printing, the trailing edge of the sheet that has completed single-sided printing and passed through the fixing unit 12 as described above is chucked by the paper discharge roller 25c. Next, the sheet is guided to the conveying rollers 25g and 25h by the reverse rotation of the paper discharge roller 25c, and after the printing on the back surface is again performed through the registration roller 14, it is discharged to the paper discharge tray 15.

Next, the configuration of the toner replenishing device 22 of the first embodiment will be specifically described.
FIG. 2 is a cross-sectional view showing a schematic configuration of a toner replenishing device constituting the image forming apparatus according to the first embodiment, and FIG. 3 is a cross-sectional view taken along a line CC in FIG.

  As shown in FIG. 2, the toner supply device 22 includes a toner container 121, a toner stirring member 125, a toner discharge member 122, and a toner discharge port 123. The toner replenishing device 22 is disposed above the developing tank 111 and stores unused toner (powdered toner). The toner in the toner replenishing device 22 is supplied to the developing tank 111 from the toner discharge port 123 via the toner transfer mechanism 102 by rotating a toner discharge member (discharge screw) 122.

  The toner storage container 121 is a substantially semi-cylindrical container member having an internal space, and rotatably supports the toner stirring member 125 and the toner discharge member 122 to store the toner. The toner discharge port 123 is a substantially rectangular opening provided below the toner discharge member 122 and from the central portion in the axial direction, and is disposed at a position facing the toner transfer mechanism 102.

  The toner agitating member 125 rotates around the rotating shaft 125 a to draw up the toner in the toner container 121 and convey it to the toner discharge member 122 while agitating the toner accommodated in the toner container 121. And a toner pumping member 125b at the tip. The toner pumping member 125 b is made of a flexible polyethylene terephthalate (PET) sheet and is attached to both ends of the toner stirring member 125.

  The toner discharge member 122 supplies the toner in the toner storage container 121 to the developing tank 111 from the toner discharge port 123, and as shown in FIG. 3, a screw including a toner transport blade 122a and a toner discharge member rotating shaft 122b. It consists of an auger. The toner discharge member 122 is rotationally driven by a toner discharge member drive motor 134. The direction of the screw auger is set so that the toner is conveyed from both axial ends of the toner discharge member 122 toward the toner discharge port 123.

  A toner discharge member partition wall 124 is provided between the toner discharge member 122 and the toner stirring member 125. Accordingly, the toner pumped up by the toner stirring member 125 can hold an appropriate amount of toner around the toner discharge member 122.

  As shown in FIG. 2, the toner stirring member 125 rotates in the direction of the arrow Z, stirs the toner, and pumps the toner toward the toner discharge member 122. At this time, the toner scooping member 125b rotates while sliding along the inner wall of the toner container 121 due to its flexibility, and supplies the toner to the toner discharging member 122 side. The supplied toner is guided to the toner discharge port 123 by the rotation of the toner discharge member 122.

Next, the characteristic developing device 2 of the first embodiment will be described with reference to the drawings.
4 is a cross-sectional view showing the configuration of the developing device constituting the image forming apparatus according to the first embodiment, FIG. 5 is a cross-sectional view taken along the line AA in FIG. 4, and FIG. 6 is a cross-sectional view taken along the line BB in FIG. FIG.

  As illustrated in FIG. 4, the developing device 2 according to the first embodiment includes a developing roller 114 disposed in the developing tank 111 so as to face the photosensitive drum 3, and the photosensitive drum 3 is developed by the developing roller 114. The apparatus supplies toner to the surface of the photosensitive drum 3 to visualize (develop) the electrostatic latent image formed on the surface of the photosensitive drum 3.

  In addition to the developing roller 114, the developing device 2 includes a developing tank 111, a developing tank cover 115, a toner supply port 115a, a doctor blade 116, a first conveying member 112, a second conveying member 113, a partition plate (partition wall) 117, A magnetic permeability sensor 118 is provided.

  The developing tank 111 is a tank for storing a two-component developer containing toner and carrier (hereinafter simply referred to as “developer”). The developing tank 111 is provided with a developing roller 114, a first conveying member 112, a second conveying member 113, and the like. Note that the carrier of the first embodiment is a magnetic carrier having magnetism.

  Further, as shown in FIG. 4, a removable developer tank cover 115 is provided on the upper side of the developer tank 111. Further, the developing tank cover 115 is provided with a toner supply port 115 a for supplying unused toner into the developing tank 111.

  As shown in FIG. 1, the toner stored in the toner replenishing device 22 is transferred into the developing tank 111 via the toner transfer mechanism 102 and the toner replenishing port 115a, whereby the toner is supplied to the developing tank 111. It has come to be.

  In the developing tank 111, as shown in FIGS. 4 and 5, a partition plate 117 is disposed between the first transport member 112 and the second transport member 113. The partition plate 117 extends in parallel with each axial direction (each rotational axis direction) of the first transport member 112 and the second transport member 113. The interior of the developing tank 111 is partitioned by a partition plate 117 into a first transport path P in which the first transport member 112 is disposed and a second transport path Q in which the second transport member 113 is disposed.

  The partition plate 117 is disposed away from the inner wall surface of the developing tank 111 at both axial ends of the first transport member 112 and the second transport member 113. Thereby, in the developing tank 111, a communication path that connects the first transport path P and the second transport path Q is formed in the vicinity of both axial ends of the first transport member 112 and the second transport member 113. ing. In the following, as shown in FIG. 5, the communication path formed on the arrow X direction side is referred to as a first communication path a, and the communication path formed on the arrow Y direction side is referred to as a second communication path b.

  The first transport member 112 and the second transport member 113 are arranged in parallel so that their peripheral surfaces face each other via the partition plate 117 and their axes are parallel to each other, and rotate in opposite directions. Is set to Then, as shown in FIG. 5, the first transport member 112 transports the developer in the arrow X direction, and the second transport member 113 transports the developer in the arrow Y direction opposite to the arrow X direction. Is set to

  As shown in FIG. 5, the first transport member 112 is constituted by a screw auger including a spiral first transport blade 112a and a first rotating shaft 112b. As shown in FIG. 5, the second transport member 113 is configured by a screw auger including a spiral second transport blade 113a and a second rotating shaft 113b. The first transport member 112 and the second transport member 113 are rotated and driven by a driving means (not shown) such as a motor to stir and transport the developer.

  As shown in FIG. 4, the developing roller 114 is disposed to face the photosensitive drum 3 and is provided so as to be separated from the photosensitive drum 3 with a gap. The developer conveyed by the developing roller 114 comes into contact with the photosensitive drum 3 at the closest portion. This contact area is the development nip N, and a development bias voltage is applied to the development roller 114 from a power source (not shown) connected to the development roller 114, and the developer on the surface of the development roller 114 is exposed to light. Toner is supplied to the electrostatic latent image on the surface of the body drum 3.

Here, the characteristic configuration of the developing roller 114 of the first embodiment will be described in detail.
As shown in FIG. 4, the developing roller 114 mainly includes a developing sleeve 119 and a magnet roller 120, and is driven to rotate around an axis by a driving unit (not shown) to remove the developer in the developing tank 111. The toner contained in the developer carried on the surface is supplied to the photosensitive drum 3.

  The developing sleeve 119 is an aluminum cylindrical member that constitutes the outer peripheral portion of the developing roller 114. The developing sleeve 119 rotates the outside of the magnet roller 120 in one direction (clockwise in FIG. 4), thereby generating the magnetic force of the magnet roller 120. Reliably transports while holding the developer.

  The magnet roller 120 includes five magnetic poles (first magnetic pole 120a to fifth magnetic pole 120e) and is fixed to the developing tank 111 in a non-rotating manner.

  The first magnetic pole 120 a is provided at a position facing the developer stirred and transported in the developing tank 111, specifically, a position facing the second transport member 113, and is stirred and transported by the second transport member 113. This is a magnetic pole for pumping up the developer. The first magnetic pole 120a is composed of an electromagnet, and is configured to be an S pole when energized.

  During a normal image forming operation, a current flows from a power source (not shown) in such a direction that the polarity on the developing sleeve 119 side of the first magnetic pole 120a is the S pole. The developer is pumped up to the developing roller 114 side.

  The second magnetic pole 120b is provided next to the downstream side in the rotation direction (clockwise in FIG. 4) of the developing sleeve 119 of the first magnetic pole 120a. The second magnetic pole 120b is made of a permanent magnet and has an N pole.

  By setting the magnetic pole on the developing sleeve 119 side of the second magnetic pole 120b to a polarity opposite to the magnetic pole on the developing sleeve 119 side of the first magnetic pole 120a (N pole in this embodiment), the second magnetic pole on the developing sleeve 119 is obtained. Magnetic field lines are formed between 120b and the first magnetic pole 120a so that the developer pumped up by the first magnetic pole 120a does not fall from the developing sleeve 119.

  The third magnetic pole 120c is provided next to the second magnetic pole 120b on the downstream side in the rotation direction of the developing sleeve 119. The third magnetic pole 120c is made of a permanent magnet and has an S pole. In the first embodiment, the third magnetic pole 120 c acts as a main magnetic pole disposed to face the photosensitive drum 3.

  By making the magnetic pole on the developing sleeve 119 side of the third magnetic pole 120c opposite to the magnetic pole on the developing sleeve 119 side of the second magnetic pole 120b (S pole in this embodiment), the third magnetic pole on the developing sleeve 119 is obtained. Magnetic lines of force are formed between 120c and the second magnetic pole 120b so that the developer held by the second magnetic pole 120b does not fall from the developing sleeve 119.

  The fourth magnetic pole 120d is provided next to the third magnetic pole 120c on the downstream side in the rotation direction of the developing sleeve 119. The fourth magnetic pole 120d is made of a permanent magnet and has an N pole.

  The magnetic pole on the developing sleeve 119 side of the fourth magnetic pole 120d is opposite in polarity (N pole in this embodiment) to the magnetic pole on the developing sleeve 119 side of the third magnetic pole 120c, so that the fourth magnetic pole is formed on the developing sleeve 119. Magnetic lines of force are formed between 120d and the third magnetic pole 120c so that the developer held by the third magnetic pole 120c does not fall from the developing sleeve 119.

  The fifth magnetic pole 120e is provided next to the fourth magnetic pole 120d on the downstream side in the rotation direction of the developing sleeve 119. The fifth magnetic pole 120e is composed of a permanent magnet and is an S pole.

  By setting the magnetic pole on the developing sleeve 119 side of the fifth magnetic pole 120e to a polarity opposite to the magnetic pole on the developing sleeve 119 side of the fourth magnetic pole 120d (S pole in this embodiment), the fifth magnetic pole on the developing sleeve 119 is obtained. Magnetic field lines are formed between 120e and the fourth magnetic pole 120d so that the developer held by the fourth magnetic pole 120d does not fall from the developing sleeve 119.

  On the other hand, the magnetic pole on the developing sleeve 119 side of the first magnetic pole 120a and the magnetic pole on the developing sleeve 119 side of the fifth magnetic pole 120e are the same (in this embodiment, the S pole). Since magnetic lines of force are not formed between 120d and the third magnetic pole 120c (a repulsive magnetic field is formed), the developer held by the third magnetic pole 120c is allowed to fall from the developing sleeve 119.

  With the configuration as described above, in the first embodiment, during the normal image forming operation, the developing roller 114 has the polarity of the first magnetic pole 120a on the developing sleeve 119 side and the polarity of the second magnetic pole 120b (N pole). The first magnetic pole 120a is used so as to prevent the developer in the developing tank 111 from being pumped during the non-image forming operation, while the current is supplied in a direction different in polarity (S pole). The amount of developer transported is reduced by stopping energization of the toner.

  As a method for reducing the developer conveyance amount (pumping amount), in addition to the above, a method of energizing the first magnetic pole 120a so that the magnetic flux density of the first magnetic pole 120a is smaller than that during image formation during non-image formation, or In order to form a repulsive magnetic field between the first magnetic pole 120a and the second magnetic pole 120b, the first magnetic pole 120a is energized so that the polarity of the first magnetic pole 120a is the same as that of the second magnetic pole 120b (N pole). Accordingly, the amount of developer conveyed by the developing sleeve 119 may be reduced.

  In the first embodiment, during the non-image forming operation, the developing roller 114, the first conveying member 112, the second conveying member 113, and the like rotate, but an electrostatic latent image is formed on the photosensitive drum 3. Say not state.

  A doctor blade 116 is disposed at a position close to the surface of the developing roller 114. As shown in FIG. 4, the doctor blade 116 is a plate-like member extending parallel to the axial direction of the developing roller 114, and one end in the short direction of the developing roller 114 is perpendicular to the surface of the developing sleeve 119. It is fixed to the developing tank 111 side so as to form a predetermined gap (doctor gap).

  In the first embodiment, the straight line passing through the center of the doctor blade 116 and the rotation axis of the developing roller 114 is located approximately in the middle between the straight line passing through the center of the first magnetic pole 120a and the straight line passing through the center of the second magnetic pole 120b. Is arranged. As the material of the doctor blade 116, stainless steel can be used, but aluminum or synthetic resin can also be used.

  The magnetic permeability sensor 118 is mounted on the bottom surface of the developing tank 111 below the second conveying member 113 in the vertical direction, and is provided so that the sensor surface is exposed inside the developing tank 111. The magnetic permeability sensor 118 is electrically connected to a toner concentration control means (not shown). The toner concentration control unit controls the toner discharge member 122 to rotate according to the toner concentration measurement value detected by the magnetic permeability sensor 118 and supply the toner into the developing tank 111 through the toner discharge port 123. .

  If it is determined that the toner density measurement value by the magnetic permeability sensor 118 is lower than the toner density setting value, a control signal is sent to the driving means for driving the toner discharge member 122 to rotate, and the toner discharge member 122 is driven to rotate. A general magnetic permeability sensor can be used as the magnetic permeability sensor 118, and examples thereof include a transmitted light detection sensor, a reflected light detection sensor, and a magnetic permeability detection sensor. Among these, a magnetic permeability detection sensor is preferable.

  A power supply (not shown) is connected to the magnetic permeability detection sensor. The power supply applies a drive voltage for driving the magnetic permeability detection sensor and a control voltage for outputting the detection result of the toner density to the control means. Application of a voltage to the magnetic permeability detection sensor by the power source is controlled by the control means. The permeability detection sensor is a type of sensor that receives the control voltage and outputs the toner density detection result as an output voltage value. Basically, the sensitivity near the median value of the output voltage is good. It is used by applying a control voltage to obtain a voltage. Such type of magnetic permeability detection sensors are commercially available, and examples thereof include TS-L, TS-A, TS-K (all are trade names, manufactured by TDK Corporation) and the like.

Here, the conveyance of the developer in the developing tank 111 of the developing device 2 will be described.
As shown in FIG. 1, the toner accommodated in the toner replenishing device 22 is transferred into the developing tank 111 through the toner transfer mechanism 102 and the toner replenishing port 115a, whereby the toner is supplied to the developing tank 111. .

  As shown in FIGS. 5 and 6, the toner replenishing port 115 a is an area in the first transport path P and is formed at a position closer to the arrow X direction than the second communication path b. That is, in the first transport path P, the toner is replenished downstream of the second communication path b.

  In the developing tank 111, the first transport member 112 and the second transport member 113 are rotationally driven by a driving means (not shown) such as a motor to transport the developer. Specifically, in the first transport path P, the developer is transported in the direction of arrow X while being stirred by the first transport member 112 and reaches the first communication path a. The developer that has reached the first communication path a passes through the first communication path a and is conveyed to the second conveyance path Q.

On the other hand, in the second transport path Q, the developer is transported in the direction of arrow Y while being stirred by the second transport member 113 and reaches the second communication path b. Then, the developer that has reached the second communication path b passes through the second communication path b and is conveyed to the first conveyance path P.
That is, the first transport member 112 and the second transport member 113 transport the developer in the opposite directions while stirring the developer.

  In this way, the developer passes through the first conveyance path P, the first communication path a, the second conveyance path Q, and the second communication path b in the developing tank 111 from the first conveyance path P to the first communication path. Circulating movement is performed in the order of a → second conveyance path Q → second communication path b. Then, while the developer is being conveyed in the second conveyance path Q, the developer is carried on the surface by the rotation of the developing roller 114 and pumped up, and the toner in the developer that has been pumped up is transferred to the photosensitive drum 3. It moves and is consumed sequentially.

  In order to make up for the consumed toner, unused toner is replenished to the first transport path P from the toner replenishing port 115a. The replenished toner is mixed and agitated with the developer existing in the first conveyance path P.

Next, the operation when the developer is conveyed by the developing device 2 according to the first embodiment will be described with reference to the drawings.
FIG. 7 is an explanatory diagram showing a state when the electromagnet (first magnetic pole) constituting the developing roller in the developing device according to the first embodiment is energized (during normal image formation), and FIG. 8 is the electromagnet (first magnetic pole). It is explanatory drawing which shows the state at the time of non-energization (at the time of non-image formation).

When image formation is performed in the developing device 2, as shown in FIG. 7, when a current flows through the first magnetic pole 120 a of the developing roller 114 and a magnetic field is formed, the second conveying path Q in the developing tank 111 is formed. The developer is pumped up to the first magnetic pole 120a and adheres to the surface of the developing sleeve 119.
The developer on the surface of the developing sleeve 119 is conveyed toward the photosensitive drum 3 as the developing sleeve 119 rotates.

  On the developing sleeve 119, magnetic lines of force are formed between the second magnetic pole 120b and the first magnetic pole 120a, so that the developer pumped up by the first magnetic pole 120a is reliably conveyed so as not to fall from the developing sleeve 119. can do.

  On the other hand, when image formation is not performed, as shown in FIG. 8, when the current to the first magnetic pole 120a is interrupted, the magnetic field is not formed, so the developer in the second transport path Q in the developing tank 111 is not formed. Remains around the second conveying member 113 without being pumped up by the first magnetic pole 120a. For this reason, the stress which a developing agent receives with the doctor blade 116 can be eliminated.

  As described above, according to the first embodiment, in the developing device 2 of the image forming apparatus 100, the magnet roller 120 constituting the developing roller 114 is configured using an electromagnet at the developer pumping position. The first magnetic pole 120a and the second magnetic pole which is provided adjacent to the downstream side in the rotation direction of the developing sleeve 119 of the first magnetic pole 120a and has a polarity (N pole) different from the polarity of the first magnetic pole 120a during image formation. 120b, magnetic lines of force are formed between the second magnetic pole 120b and the first magnetic pole 120a during image formation, so that the developer pumped up by the first magnetic pole 120a does not fall from the developing sleeve 119. In addition, it can be reliably conveyed.

  On the other hand, at the time of non-image formation, the first magnetic pole 120a is deenergized so that a magnetic field is not formed, so that the developer cannot be pumped up by the developing roller 114. Thereby, the developer conveyed to the doctor blade 116 can be reduced. As a result, the stress applied when the developer is regulated by the doctor blade 116 can be eliminated.

  Therefore, according to the image forming apparatus 100 of the first embodiment, since the developing device 2 can suppress the wear of the developer, the image density unevenness can be suppressed and an image with stable image quality can be obtained.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings.
FIG. 9 is a cross-sectional view illustrating a configuration of a developing device according to the second embodiment.

In the developing device 202 according to the second embodiment, the first magnetic pole is configured using an electromagnet and a permanent magnet instead of the configuration of the first magnetic pole 120a using the electromagnet of the first embodiment.
Therefore, the configuration of the developing device 202 according to the second embodiment has the same configuration as the configuration of the developing device 2 according to the first embodiment except that the first magnetic pole is configured using an electromagnet and a permanent magnet. Therefore, in the second embodiment, those having the same configuration and function as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 9, the developing device 202 according to the second embodiment includes a developing roller 214, a developing tank 111, a developing tank cover 115, a toner supply port 115a, a doctor blade 116, a first conveying member 112, and a second conveying member. 113, a partition plate (partition wall) 117, and a magnetic permeability sensor 118.

  The developing roller 214 mainly includes a developing sleeve 219 and a magnet roller 220. The developing roller 214 is rotationally driven around a shaft center by a driving unit (not shown) to draw and carry the developer in the developing tank 111 onto the surface of the developing sleeve 219. The toner contained in the developer carried on the surface is supplied to the photosensitive drum 3.

  The developing sleeve 219 is an aluminum cylindrical member that constitutes the outer peripheral portion of the developing roller 214. The developing sleeve 219 rotates the outer side of the magnet roller 220 in one direction (clockwise in FIG. 9), thereby generating the magnetic force of the magnet roller 220. Reliably transports while holding the developer.

  The magnet roller 220 includes five magnetic poles (first magnetic pole 220a to fifth magnetic pole 220e) and is fixed to the developing tank 111 so as not to rotate.

  The first magnetic pole 220 a is a pumping magnetic pole that is provided at a position facing the second transport member 113 and pumps up the developer stirred and transported by the second transport member 113. The first magnetic pole 220a is composed of an electromagnet 220aa and a permanent magnet 220ab, and has a sandwich shape in which the permanent magnet 220ab is sandwiched between the electromagnets 220aa.

  The permanent magnet 220ab is arranged in such a direction that the polarity on the developing sleeve 219 side is the south pole, and during normal image forming operation, the developer in the developing tank 111 is pumped up even if no current flows through the electromagnet 220aa. Can be done.

  The second magnetic pole 220b is provided next to the downstream side in the rotation direction (clockwise in FIG. 9) of the developing sleeve 219 of the first magnetic pole 220a. The second magnetic pole 220b is made of a permanent magnet and has an N pole.

  By making the magnetic pole on the developing sleeve 219 side of the second magnetic pole 220b opposite to the magnetic pole on the developing sleeve 219 side of the first magnetic pole 220a (N pole in the present embodiment), the second magnetic pole on the developing sleeve 219 is obtained. Magnetic field lines are formed between 220b and the first magnetic pole 220a so that the developer pumped up by the first magnetic pole 220a does not fall from the developing sleeve 219.

  The third magnetic pole 220c is provided next to the second magnetic pole 220b on the downstream side in the rotation direction of the developing sleeve 219. The third magnetic pole 220c is composed of a permanent magnet and is an S pole. In the second embodiment, the third magnetic pole 220 c acts as a main magnetic pole disposed to face the photosensitive drum 3.

  By making the magnetic pole on the developing sleeve 219 side of the third magnetic pole 220c opposite to the magnetic pole on the developing sleeve 219 side of the second magnetic pole 220b (S pole in this embodiment), the third magnetic pole on the developing sleeve 219 is obtained. Magnetic lines of force are formed between 220c and the second magnetic pole 220b so that the developer held by the second magnetic pole 220b does not fall from the developing sleeve 219.

  The fourth magnetic pole 220d is provided next to the third magnetic pole 220c on the downstream side in the rotation direction of the developing sleeve 219. The fourth magnetic pole 220d is made of a permanent magnet and has an N pole.

  The magnetic pole on the developing sleeve 219 side of the fourth magnetic pole 220d has a polarity opposite to that of the third magnetic pole 220c on the developing sleeve 219 side (N pole in this embodiment), so that the fourth magnetic pole is formed on the developing sleeve 219. Magnetic field lines are formed between 220d and the third magnetic pole 220c so that the developer held by the third magnetic pole 220c does not fall from the developing sleeve 219.

  The fifth magnetic pole 220e is provided next to the fourth magnetic pole 220d on the downstream side in the rotation direction of the developing sleeve 219. The fifth magnetic pole 220e is formed of a permanent magnet and is an S pole.

  By making the magnetic pole on the developing sleeve 219 side of the fifth magnetic pole 220e opposite to the magnetic pole on the developing sleeve 219 side of the fourth magnetic pole 220d (S pole in this embodiment), the fifth magnetic pole on the developing sleeve 219 is obtained. Magnetic lines of force are formed between 220e and the fourth magnetic pole 220d so that the developer held by the fourth magnetic pole 220d does not fall from the developing sleeve 219.

  On the other hand, the magnetic pole on the developing sleeve 219 side of the first magnetic pole 220a and the magnetic pole on the developing sleeve 219 side of the fifth magnetic pole 220e are the same (S pole in this embodiment), and therefore the fourth magnetic pole on the developing sleeve 219. Since magnetic lines of force are not formed between 220d and the third magnetic pole 220c (a repulsive magnetic field is formed), the developer held by the third magnetic pole 220c falls from the developing sleeve 219.

  With the configuration described above, in the second embodiment, the developing roller 214 pumps up the developer by the magnetic force of the permanent magnet 220ab by stopping energization of the electromagnet 220aa during the normal image forming operation. On the other hand, during the non-image forming operation, the electromagnet 220aa is energized in such a direction as to cancel the magnetic force of the permanent magnet 220ab so as not to draw up the developer.

  That is, the normal of the surface of the developing sleeve 219 in the direction in which the polarity of the electromagnet 220aa on the developing sleeve 219 has a polarity (N pole) different from the polarity (S pole) of the permanent magnet 220ab and close to the first magnetic pole 220a. By energizing the magnetic flux density in the direction to be zero, the pumping amount of the developer is reduced.

  In addition to the method described above, the developer transport amount (pumping amount) can be reduced from the time of image formation even if the magnetic flux density in the normal direction on the surface of the developing sleeve 219 adjacent to the first magnetic pole 220a does not become zero. In order to reduce the current, or to form a repulsive magnetic field between the first magnetic pole 220a and the second magnetic pole 220b, the polarity of the first magnetic pole 220a is the same as the polarity of the second magnetic pole 220b (N pole). The amount of developer transported by the developing sleeve 219 may be reduced by energizing the first magnetic pole 220a so that

  As described above, according to the second embodiment, in the developing device 202, as the configuration of the magnet roller 220 constituting the developing roller 214, the electromagnet 220aa and the permanent magnet 220ab are used at the developer pumping position. A first magnetic pole 220a configured and a second magnetic pole provided adjacent to the downstream side in the rotation direction of the developing sleeve 219 of the first magnetic pole 220a and having a polarity (N pole) different from the polarity of the first magnetic pole 220a during image formation. By providing the magnetic poles, the magnetic lines of force are formed between the second magnetic pole 220b and the first magnetic pole 220a by the permanent magnet 220ab by stopping energization of the electromagnet 220aa during image formation, and therefore the first magnetic pole 220a. Thus, the developer pumped up in step S1 can be reliably conveyed so that it does not fall from the developing sleeve 119.

  On the other hand, during non-image formation, the electromagnet 220aa of the first magnetic pole 220a is energized so that a magnetic force is generated in a direction to cancel the magnetic force of the permanent magnet 220ab, so that no magnetic field is formed. It will not be pumped up. Thereby, the developer conveyed to the doctor blade 116 can be reduced as in the first embodiment. As a result, the stress applied when the developer is regulated by the doctor blade 116 can be eliminated.

  In the above-described embodiment, the example in which the developing devices 2 and 202 according to the present invention are applied to the image forming apparatus 100 as shown in FIG. 1 has been described. However, the developer stirred in the developing tank 111 is used as the developing roller. The image forming apparatus using the developing device supported by 114 is not limited to the image forming apparatus and the copying machine having the above-described configuration, and can be expanded to other image forming apparatuses. .

  As described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. That is, embodiments obtained by combining technical means appropriately changed within the scope not departing from the gist of the present invention are also included in the technical scope of the present invention.

1 Exposure unit (exposure equipment)
2,202 Development device 3 Photosensitive drum 5 Charger (charging device)
8 Intermediate transfer belt unit (transfer device)
12 Fixing unit (fixing device)
100 Image forming apparatus 111 Developing tank 112 First conveying member 113 Second conveying member 114, 214 Developing roller 116 Doctor blade 119, 219 Developing sleeve 120, 220 Magnet roller 120a, 220a First magnetic pole 120b, 220b Second magnetic pole 120c, 220c Third magnetic pole 120d, 220d Fourth magnetic pole 120e, 220e Fifth magnetic pole 220aa Electromagnet 220ab Permanent magnet

Claims (4)

A developer tank containing a developer including toner and a carrier; a developing roller for pumping the developer at a position facing the developer in the developer tank and supplying the toner to the photosensitive drum; and the developer roller. A regulating member that regulates the amount of developer supplied, and the developing roller is a cylindrical developing sleeve that is rotatably provided with respect to the developing tank, and a plurality that is provided non-rotating with respect to the developing tank. In a developing device comprising a magnet roller having a magnetic pole of
The magnet roller is provided adjacent to a first magnetic pole formed by using an electromagnet at a position where the developer is pumped, and downstream of the first magnetic pole in the developing sleeve rotation direction, and the first magnetic pole at the time of image formation. A second magnetic pole having a polarity different from the polarity of
The developing device according to claim 1, wherein the first magnetic pole has a magnetic flux density at the time of non-image formation smaller than a magnetic flux density at the time of image formation, or a polarity at the time of non-image formation is the same as the polarity of the second magnetic pole. The first magnetic pole is configured using a permanent magnet in addition to an electromagnet,
The developing device according to claim 1, wherein a polarity of the permanent magnet is different from a polarity of the second magnetic pole during image formation.   The developing device according to claim 2, wherein the first magnetic pole is configured such that both sides of the permanent magnet are sandwiched between the electromagnets. A photosensitive drum on which an electrostatic latent image is formed; a charging device that charges the surface of the photosensitive drum; an exposure device that forms an electrostatic latent image on the surface of the photosensitive drum; A developing device that supplies toner to the electrostatic latent image to form a toner image; a transfer device that transfers the toner image to a recording medium; and a fixing device that fixes the transferred toner image to the recording medium. In an image forming apparatus for forming an image using toner by electrophotography,
An image forming apparatus using the developing device according to claim 1 as the developing device.

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