JP5539708B2 - Developing device and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a developing device that forms a toner image on a predetermined image carrier and an image forming apparatus including the developing device.

  An image forming apparatus such as a copying machine, a printer, a facsimile machine, or a combination machine using an electrophotographic system supplies toner to an image carrier (for example, a photosensitive drum or a transfer belt) and puts the toner on the image carrier. A developing device for forming a toner image;

  The developing device includes, as basic components, a developer storage unit that stores the developer, and receives the developer from the developer storage unit and supplies the developer to the image carrier, thereby the image carrier. The developer layer on the outer peripheral surface is disposed so as to face the outer peripheral surface so that a predetermined regulating gap is formed between the developing roller on which the toner image is formed and the outer peripheral surface of the developing roller. (For example, patent document 1).

  In the developing device of Patent Document 1, the developing roller has a built-in magnet roll for drawing up developer on the outer peripheral surface thereof, and the regulating blade is made of a magnetic material. Since the magnetic field of the magnetic pole facing the regulating blade in the magnet roll is concentrated on the regulating blade, the regulating blade has a developer gap (so-called magnetic brush layer) on the outer peripheral surface in the regulating gap where the magnetic field acts. It can regulate so that layer thickness may become uniform.

JP 54-43037 A

  However, in the developing device of Patent Document 1, the amount of developer conveyed to the regulation blade is much larger than the amount of developer passing through the regulation gap as a magnetic brush layer, and therefore the magnetic field around the regulation blade is reduced. The developer tends to stay in a range that does not reach. The staying developer deteriorates by colliding with each other or colliding with a wall portion that defines the developer storing portion. Further, the staying developer tends to be in a compressed state, that is, a so-called packing state, and deteriorates. When the developer deteriorates in this way, it becomes difficult to form a good toner image on the image carrier.

  Therefore, in view of the above circumstances, the present invention provides a developing device capable of forming a good toner image on an image carrier while suppressing the deterioration of the developer, and an image forming apparatus including the developing device. With the goal.

In order to achieve the above object, a developing device according to the present invention includes a developer storage unit that stores a developer containing non-magnetic toner and a magnetic carrier while stirring, and a first magnet. A predetermined regulation between the developer carrier and the developer carrier that receives the developer from the developer reservoir and supplies the developer to the predetermined image carrier while rotating in a predetermined direction. A magnetic path is formed with the first magnet so that a gap is formed, and a magnetic layer is formed between the first magnet and the thickness of the developer on the developer carrier. And a magnetic pole having the same polarity as the first magnet, and a first regulating member made of a magnetic material that regulates the first and second developer members, and a first regulating member that is disposed upstream of the first regulating member when viewed from the rotation direction of the developer carrier. And a second magnet having the developer carrier as viewed from the direction of rotation. The amount of the developer that is located upstream from the two magnets and that is gradually separated from the developer carrier as it goes upstream in the rotational direction, and is conveyed to the first regulating member A second restricting member having a transport amount restricting surface for restricting the upstream side, the first restricting member facing the upstream side when viewed from the rotation direction of the developer carrying member, and the developer carrying member. And a layer thickness regulating surface that regulates the layer thickness of the developer. The second magnet is joined to the upstream surface, and the second regulating member is joined to the upstream surface of the second magnet. The second restricting member is connected to the upstream surface of the second magnet and has a base end portion having a portion closest to the developer carrier, and the base end portion is directed upstream in the rotational direction. A main body portion that extends, and the transport amount regulating surface is formed on the main body portion. The conveyance amount regulating surface, by a predetermined angle on the side by the developer carrier with respect to the layer thickness regulating surface, between the outer peripheral surface of said developer carrying member and the conveyance amount regulating face The space is narrowed toward the downstream side in the rotation direction, and the space is narrowed by the developer that the magnetic field generated between the first magnet and the first restricting member reaches, and the narrowed portion. space der accommodating a developer to be pushed back to the upstream side of the rotational direction by is, the second magnet enhances the magnetic flux density of the magnetic field generated between the first regulating member and the first magnet The magnetic field is generated, and the second magnet has a facing surface facing the developer carrier, and the layer thickness regulating surface and the facing surface are set to be substantially flush with each other. Tei Ru.

  According to the developing device of the present invention, the transport amount regulating surface of the second regulating member is set so as to be gradually separated from the developer carrier as it goes upstream in the rotation direction of the developer carrier. The amount of developer transported toward the first regulating member is regulated. Therefore, an amount of developer that can be reached by the magnetic field generated between the first magnet and the first restricting member is conveyed toward the first restricting member. Thereby, the layer thickness of the developer layer is appropriately regulated by the first regulating member, and the developer is suppressed from staying in a range where the magnetic field around the first regulating member does not reach. As a result, the deterioration of the developer due to the stay is suppressed.

  In addition, a second magnet having a magnetic pole having the same polarity as that of the first magnet is disposed on the upstream side of the first restricting member when viewed from the rotation direction of the developer carrying member, so that the magnetic field generated by the second magnet The magnetic flux density of the magnetic field generated between the first regulating member and the first magnet can be increased. Therefore, the range covered by the magnetic field between the first restricting member and the first magnet is increased, and the distance between the first restricting member and the developer carrier, that is, the restricting gap can be increased. Thereby, the conveyance of the developer is stabilized and the stress received when the developer is regulated by the first regulating member is reduced.

In a preferred embodiment of the present invention, the first regulating member has a layer thickness regulating surface that regulates the layer thickness of the developer so as to face the developer carrying member, and the second regulating member comprises: A base end portion which is joined to the upstream surface of the second magnet and has a portion closest to the developer carrier, and a main body portion extending from the base end portion toward the upstream side in the rotation direction, The carry amount regulating surface is formed on the main body, and the carry amount regulating surface forms a predetermined angle on the side closer to the developer carrying member with respect to the layer thickness regulating surface.

  According to this configuration, the size of the space between the conveyance amount regulating surface and the developer carrier can be adjusted by appropriately setting a predetermined angle of the conveyance amount regulating surface with respect to the layer thickness regulating surface. It is easy to set the amount of developer conveyed toward the first regulating member.

In another preferred embodiment of the present invention, the first regulating member has a layer thickness regulating surface that regulates the layer thickness of the developer facing the developer carrying member, and the second magnet is , have a facing surface that faces the developer carrier, wherein the regulating surface and the opposing surface is set such that the state of substantially flush.

  According to this configuration, since the second magnet is joined to the upstream surface of the first restricting member, no gap is formed between the second magnet and the upstream surface so that the developer is retained. Further, since the layer thickness regulating surface of the first regulating member and the opposing surface of the second magnet are set to be substantially flush with each other, the developer stays between the layer thickness regulating surface and the opposing surface. Such a step is not formed. Thereby, the conveyance amount of the developer conveyed toward the first regulating member can be further stabilized.

  In still another preferred embodiment of the present invention, the second restriction member is made of a nonmagnetic material.

  According to this configuration, since the second restricting member is formed of a non-magnetic material, when the charged developer is conveyed toward the first restricting member, the second restricting member is placed on the conveyance amount restricting surface of the second restricting member. It becomes difficult to adhere.

  The developing device according to the present invention includes: an image carrier on which a toner image is formed; a developing device that supplies toner to the image carrier to form the toner image on the image carrier; and the toner image on a sheet A developing device having the above-described configuration is employed as the developing device, including a transfer member to be transferred onto the sheet and a fixing unit that fixes the toner image on the sheet onto the sheet.

  According to the developing device and the image forming apparatus of the present invention, it is possible to form a good toner image on the image carrier while suppressing the deterioration of the developer.

1 schematically shows an internal structure of an image forming apparatus according to an embodiment of the present invention. It is sectional drawing which shows the internal structure of a developing device roughly. It is an enlarged view of a developing device, and shows the periphery of a developer regulating blade. It is a figure which shows the modification of the conveyance amount regulation member of a developing device. It is a figure which shows the developing device of the form using only a developer control blade and a conveyance amount control member. It is a figure which shows the image development apparatus of the form using only a developer control blade and a magnet member.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

  FIG. 1 schematically shows an internal structure of the image forming apparatus according to the present embodiment. The image forming apparatus 10 is, for example, a tandem color printer, and includes an apparatus main body 11 having a box shape. The apparatus main body 11 includes an image forming unit 12 that forms an image based on image information transmitted from an external device such as a computer, and an image formed by the image forming unit 12 and transferred to a sheet P (sheet). A fixing unit 13 that performs a fixing process and a paper storage unit 14 that stores the transfer paper P are included. A paper discharge unit 15 for discharging the paper P after the fixing process is provided on the upper portion of the apparatus main body 11.

  The image forming unit 12 forms a toner image on the paper P fed from the paper storage unit 14. In the present embodiment, the image forming unit 12 is directed from the upstream side (right side of the paper surface in FIG. 1) to the downstream side. Sequentially arranged magenta unit 12M using magenta toner (developer), cyan unit 12C using cyan toner, yellow unit 12Y using yellow toner, and black toner And a black unit 12K.

  Each unit 12M, 12C, 12Y, 12K includes a photosensitive drum 121 and a developing device 20. The photosensitive drum 121 forms an electrostatic latent image and a toner image (visible image) along the electrostatic latent image on the peripheral surface, and corresponds to the development while rotating counterclockwise in FIG. Toner is supplied from the apparatus 20. Each developing device 20 is supplied with toner from a toner cartridge (not shown).

  A charging device 123 is provided immediately below each photosensitive drum 121, and an exposure device 124 is provided below each charging device 123. The circumferential surface of each photosensitive drum 121 is uniformly charged by a charging device 123, and laser light corresponding to each color based on image data input from a computer or the like is charged from the exposure device 124 to the circumference of the photosensitive drum 121 after charging. The surface is irradiated. Thereby, an electrostatic latent image is formed on the peripheral surface of each photosensitive drum 121. When toner is supplied to the electrostatic latent image from the developing device 20, a toner image is formed on the peripheral surface of the photosensitive drum 121.

  Above the photosensitive drum 121, a transfer belt 125 is disposed between the driving roller 125a and the driven roller 125b. The transfer belt 125 is pressed against the circumferential surface of the photosensitive drum 121 by a transfer roller 126 provided corresponding to each photosensitive drum 121, and is driven with a driving roller 125 a and a driven roller in synchronization with the photosensitive drum 121. Circulate between 125b.

  Along with the rotation of the transfer belt 125, first, primary transfer of a magenta toner image is performed on the surface of the transfer belt 125 by the photosensitive drum 121 of the magenta unit 12M. Next, the cyan toner image is transferred to the transfer position of the magenta toner image on the transfer belt 125 by the photosensitive drum 121 of the cyan unit 12C in an overcoated state. Similarly, the transfer of the yellow toner image by the yellow unit 12Y and the transfer of the black toner image by the black unit 12K are performed in the overcoating state. As a result, a color toner image is formed on the surface of the transfer belt 125.

  A drum cleaning device 127 that removes and cleans residual toner on the peripheral surface of the photosensitive drum 121 is provided at the left position of each photosensitive drum 121 in FIG. The peripheral surface of the photosensitive drum 121 cleaned by the drum cleaning device 127 goes to the charging device 123 for a new charging process. Waste toner removed from the peripheral surface of the photosensitive drum 121 by the drum cleaning device 127 is collected in a toner collection bottle (not shown) through a predetermined path.

  At the left position of the image forming unit 12 in FIG. 1, a paper conveyance path 111 extending in the vertical direction is formed. A conveyance roller pair 112 is provided at an appropriate position on the sheet conveyance path 111, and the sheet P from the sheet storage unit 14 is conveyed toward the transfer belt 125 by driving the conveyance roller pair 112. In addition, a secondary transfer roller 113 that is in contact with the surface (image carrying surface) of the transfer belt 125 at a position facing the driving roller 125a is provided in the sheet conveyance path 111. The secondary transfer roller 113 forms a transfer nip portion with the image carrying surface of the transfer belt 125. The sheet P is pressed and nipped by the transfer belt 125 and the secondary transfer roller 113 at the transfer nip portion, whereby the toner image on the transfer belt 125 is secondarily transferred to the sheet P.

  The sheet storage unit 14 includes a manual feed tray 141 that can be freely opened and closed on the right side wall of the apparatus main body 11 in FIG. 1, and a paper tray 142 that is removably mounted in the apparatus main body 11 below the exposure device 124. including. In the paper tray 142, a paper bundle P1 formed by stacking a plurality of papers P is stored. The paper tray 142 is configured by a box that opens upward, and the paper bundle P1 can be stored. The uppermost sheet P of the sheet bundle P1 stored in the sheet tray 142 is fed out one by one toward the sheet conveyance path 111 by driving the pickup roller 143. The paper P fed out from the paper tray 142 is conveyed toward the transfer nip portion through the paper conveyance path 111 by driving the conveyance roller pair 112.

  The fixing unit 13 performs a fixing process on the toner image on the sheet P that has been secondarily transferred. The fixing unit 13 includes a heating roller 131 having an energized heating element as a heating source therein, a fixing roller 132 disposed to face the heating roller 131, and a fixing belt 133 stretched between the fixing roller 132 and the heating roller 131. And a pressure roller 134 disposed to face the fixing roller 40 with the fixing belt 133 interposed therebetween. The sheet P supplied to the fixing unit 13 is subjected to a fixing process by obtaining heat from the fixing belt 133 while passing between the pressure roller 134 and the high-temperature fixing belt 133. The color-printed paper P for which the fixing process has been completed is discharged toward the paper discharge tray 151 of the paper discharge section 15 through the paper discharge conveyance path 114 extended from the upper part of the fixing section 13.

  FIG. 2 is a cross-sectional view schematically showing the internal structure of the developing device 20. The developing device 20 includes a developing container 21 that defines an internal space thereof. The developing device 20 is disposed above the developer storage unit 22 and a developer storage unit 22 that stores the developer in the developer container 21 and can transport the developer while stirring. A developing roller 23 (developer carrying member) and a developer regulating blade 24 (first regulating member) disposed to face the developing roller 23 are included.

  The developer storage unit 22 is composed of two adjacent developer storage chambers 25 and 26 extending in the longitudinal direction of the developing device 20, and the developer storage chambers 25 and 26 are formed integrally with the developing container 21. The partition plates 27 partition each other in the longitudinal direction, but communicate with each other at both ends in the longitudinal direction. In addition, screw feeders 28 and 29 for stirring the developer by rotation are rotatably mounted in the developer storage chambers 25 and 26, respectively. Since the screw feeders 28 and 29 are set to rotate in opposite directions, the developer is conveyed between the developer storage chamber 25 and the developer storage chamber 26 while being stirred. By this stirring, the toner made of a magnetic material and the carrier made of a non-magnetic material are mixed to charge the toner.

  The developing roller 23 is disposed so as to extend in the longitudinal direction of the developing device 20, and can rotate counterclockwise in FIG. The developing roller 23 contains a fixed so-called magnet roll (not shown) extending in the longitudinal direction of the developing roller. The magnet roll is formed with a pumping pole 31 for magnetically pumping up the developer from the developer reservoir 25 onto the outer peripheral surface 30 of the developing roller 23. The developer pumped up by the pumping pole 31 is magnetically held on the outer peripheral surface 30 of the developing roller 23 and is conveyed toward the developer regulating blade 24 as the developing roller 23 rotates.

  The developer regulating blade 24 regulates the layer thickness of the developer layer that is magnetically attached to the outer peripheral surface 30 of the developing roller 23. The developer regulating blade 24 is a plate member made of a magnetic material that extends along the longitudinal direction of the developing roller 23, and is supported at an appropriate position of the developing container 21.

  Further, as shown in FIG. 3, the developer regulating blade 24 has a leading end surface (hereinafter referred to as a layer thickness regulating surface 35) that forms a predetermined regulating gap G with the outer peripheral surface 30 of the developing roller 23. The developer regulating blade 24 regulates the layer thickness of the developer layer via the layer thickness regulating surface 35.

  The developer whose layer thickness is regulated is transported toward the photosensitive drum 121 as the developing roller 23 rotates, and a development bias applied to the developing roller 23 and a drum bias applied to the photosensitive drum 121. It adheres to the electrostatic latent image on the photosensitive drum 121 due to the potential difference. As a result, a toner image is formed on the photosensitive drum 121.

  In the magnet roll of the developing roller 23, a regulating pole 32 is formed at a position facing the layer thickness regulating surface 35 of the developer regulating blade 24 in addition to the scooping pole 31. Therefore, the developer regulating blade 24 formed of a magnetic material is magnetized by the regulating pole 32 of the developing roller 23, and between the layer thickness regulating surface 35 and the regulating pole 32 of the developer regulating blade 24, that is, the regulating gap G. A magnetic path is formed. The drawing pole 31 and the regulation pole 32 are formed over substantially the same longitudinal dimension as the developing roller 23.

  A magnet member 33 is disposed on the upstream side of the developer regulating blade 24 when viewed from the rotation direction of the developing roller 23. The developer regulating blade 24 has an upstream surface 36 facing the upstream side in the rotational direction, and a magnet member 33 is joined to the upstream surface 36. The magnet member 33 is a plate-like member that extends in the longitudinal direction of the developing device 20 along the developer regulating blade 24.

  The magnet member 33 has a distal end portion 37 extending toward the developing roller 23, and a magnetic pole having the same polarity as the regulation pole 32 is formed at the distal end portion 37. The magnetic field generated by the magnet member 33 increases the magnetic flux density of the magnetic field (magnetic path) generated between the developer regulating blade 24 and the regulating pole 32.

  Further, the tip portion 37 of the magnet member 33 has a facing surface 38 that faces the developing roller 23. The thickness of the magnet member 33 on the facing surface 38 is defined in the rotation direction of the developing roller 23. The facing surface 38 and the layer thickness regulating surface 35 of the developer regulating blade 24 are set to be substantially flush with each other. Thereby, no step is formed between the facing surface 38 and the layer thickness regulating surface 35.

  A transport amount regulating member 34 (second regulating member) is disposed on the upstream side of the magnet member 33 when viewed from the rotation direction of the developing roller 23. The conveyance amount regulating member 34 is a plate-like member having a width dimension substantially the same as the longitudinal dimension of the developing roller 23 and formed from a nonmagnetic material such as a resin. The conveyance amount regulating member 34 is connected to the upstream surface 39 of the magnet member 33 as viewed from the rotation direction of the developing roller 23, the upstream side in the rotation direction of the developing roller 23 from the proximal end portion 40, and And a main body 41 extending along the outer peripheral surface 30 of the developing roller 23.

  The main body 41 has a flat surface (hereinafter referred to as a conveyance amount regulating surface 42) that faces the outer peripheral surface 30 of the developing roller 23. The main body 41 is set so as to be gradually separated from the developing roller 23 toward the upstream side in the rotational direction. In other words, the space S between the conveyance amount regulating surface 42 and the outer peripheral surface 30 of the developing roller 23 gradually increases as the conveyance amount regulating surface 42 of the main body 41 moves toward the upstream side in the rotation direction of the developing roller 23. It is set to be. The carry amount regulating member 34 regulates the carry amount of the developer conveyed toward the developer regulating blade 24 by the carry amount regulating surface 42.

  However, it is not desirable for the space S to be expanded, and the transport amount regulating surface 42 is a predetermined angle (hereinafter, referred to as a side of the developer regulating blade 24 closer to the developing roller 23 with respect to the layer thickness regulating surface 35). It is set so as to form a restriction angle α). By appropriately setting the restriction angle α, the size of the space S between the conveyance amount restriction surface 42 and the outer peripheral surface 30 of the developing roller 23 can be adjusted. By appropriately setting the size of the space S, the transport amount of the developer transported to the developer regulating blade 24 is set. Note that the transport amount regulating surface 42 does not necessarily have to be set so as to form a predetermined regulating angle α with respect to the layer thickness regulating surface 35, and is substantially flush with the layer thickness regulating surface 35 as shown in FIG. You may set so that it may be located on the upper side (in other words, it may become right angle with respect to the upstream surface 39). Further, the length of the transport amount regulating surface 42 extending to the upstream side in the rotation direction of the developing roller 23 is appropriately set.

  In the developing device 20 configured as described above, the developer is regulated as follows. That is, the developer magnetically adhering from the developer storage chamber 25 to the outer peripheral surface 30 of the developing roller 23 by the drawing upper pole 31 is caused by the rotation of the developing roller 23 as shown in the arrow A. Gradually approach the transport amount regulating surface 42. The developer is transported to the space S between the transport amount regulating surface 42 and the outer peripheral surface 30 of the developing roller 23, and the space S becomes narrower toward the downstream side in the rotation direction of the developing roller 23. Therefore, a part of the developer being conveyed is gradually pushed back in the direction (arrow B) opposite to the rotation direction of the developing roller 23 (counterclockwise in FIG. 3) by the conveyance amount regulating surface 42. Return to the storage chamber 25. In this way, the transport amount of the developer transported to the developer regulating blade 24 is regulated by the transport amount regulating surface 42.

  For this reason, an amount of developer to which a magnetic field generated between the regulation pole 32 and the developer regulation blade 24 reaches is conveyed toward the developer regulation blade 24. Thus, the developer regulating blade 24 appropriately regulates the layer thickness of the developer layer (so-called magnetic brush layer). Further, unlike the conventional configuration in which the amount of developer conveyed to the developer regulating blade is much larger than the amount of developer passing through the regulating gap as a magnetic brush layer, the magnetic field around the developer regulating blade 24 It is possible to prevent the developer from staying within a range that does not reach. As a result, the deterioration of the developer due to the stay is suppressed.

  In addition, a magnet member 33 having a magnetic pole having the same polarity as that of the regulating pole 32 is disposed on the upstream side of the developer regulating blade 24 when viewed from the rotation direction of the developing roller 23. The magnetic flux density of the magnetic field generated between the developer regulating blade 24 and the regulating pole 32 can be increased. Therefore, the range covered by the magnetic field between the developer regulating blade 24 and the regulating pole 32 is increased, and the distance between the developer regulating blade 24 and the developing roller 23, that is, the regulating gap G can be increased. As a result, the conveyance of the developer is stabilized and the stress received when the developer is regulated by the developer regulating blade 24 is reduced.

  Further, according to the developing device 20, the size of the space S between the conveyance amount regulating surface 42 and the outer peripheral surface 30 of the developing roller 23 can be adjusted by appropriately setting the regulating angle α. It is easy to set the amount of developer conveyed toward the agent regulating blade 24.

  Further, according to the developing device 20, the magnet member 33 is joined to the upstream surface 36 of the developer regulating blade 24, so that the developer stays between the magnet member 33 and the upstream surface 36. No gaps are formed. Further, since the layer thickness regulating surface 35 of the developer regulating blade 24 and the facing surface 38 of the magnet member 33 are set to be substantially flush with each other, the developer is also interposed between the layer thickness regulating surface 35 and the facing surface 38. Is not formed. Thereby, the conveyance amount of the developer conveyed toward the developer regulating blade 24 can be further stabilized.

  Further, according to the developing device 20, since the transport amount regulating member 34 is formed of a non-magnetic material such as resin, the developer transported toward the developer regulating blade 24 in a charged state is transported. When the conveyance amount is regulated by the amount regulation surface 42, it is difficult to adhere to the conveyance amount regulation surface 42.

Hereinafter, an experiment performed using the developing device 20 will be described. In this experiment, it was examined how the transport amount (mg / cm ² ) of the developer layer (magnetic brush layer) that passed through the regulation gap G fluctuated when the size of the regulation gap G was changed. . As an experiment object, the regulation angle α of the conveyance amount regulation surface 42, the thickness of the magnet member 33, the magnetic force of the magnet member 33, and the size of the step between the layer thickness regulation surface 35 and the facing surface 38 were varied. Examples 1-4 and Comparative Examples 1-6 were used. Table 1 shows the setting conditions of Examples 1 to 4 and Comparative Examples 1 to 6. Comparative Example 1 is a form using only the developer regulating blade 24, and Comparative Example 2 is a form using the developer regulating blade 24 and the transport amount regulating member 34 as shown in FIG. -6 is a form using the developer control blade 24 and the magnet member 33, as shown in FIG. On the other hand, Examples 1 to 4 are forms using a transport amount regulating member 34 and a magnet member 33 in addition to the developer regulating blade 24 as shown in FIG.

  Further, in the experiment, the developing roller 23 subjected to blasting is used, the toner having an average particle diameter of 6.8 μm, T / C (the ratio of toner to carrier) of 11%, the average particle diameter of 35 μm, and the saturation magnetization of 60 emu. A developer containing / g carrier was used. The developer transport amount was measured after operating the developing devices of Examples 1 to 4 and Comparative Examples 1 to 6 for a predetermined time. The results are shown in Tables 2 and 3.

  As shown in Table 2, in Comparative Example 1 in which only the developer regulating blade 24 was used, the developer conveyance amount increased rapidly as the regulation gap G increased. Also in Comparative Example 2 using the developer regulating blade 24 and the conveyance amount regulating member 34, the developer conveyance amount rapidly increased as the regulation gap G increased.

In Comparative Examples 3, 4, and 6 using the developer regulating blade 24 and the magnet member 33, the developer transport amount was suppressed to 20 mg / cm ² or less even when the regulating gap G was increased. There was no stability against changes. In Comparative Example 5, the developer restraining force by the developer regulating blade 24 was too strong to form the magnetic brush layer.

On the other hand, in Examples 1-4 using the developer regulating blade 24, the carry amount regulating member 34, and the magnet member 33, a low carry amount of 10 mg / cm ² or less can be realized even if the restriction gap G is increased. did it. Further, the transport amount can be stabilized against changes in the regulation gap G. Thus, by using the transport amount regulating member 34 and the magnet member 33 in addition to the developer regulating blade 24, it is possible to realize a low developer transport amount and stabilization of the transport amount.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 20 Developing apparatus 21 Developer container 22 Developer storage part 23 Developing roller (developer carrier)
24 Developer regulating blade (first regulating member)
31 Upper electrode 32 Restriction electrode 33 Magnet member 34 Conveyance amount regulating member (second regulating member)
35 Layer thickness regulating surface 38 Opposing surface 40 Base end portion 41 Main body portion 42 Conveyance amount regulating surface G Regulation gap S Space

Claims (3)

A developer storage section for storing a developer containing a non-magnetic toner and a magnetic carrier while stirring;
A developer carrier having a first magnet and receiving the developer from the developer reservoir and supplying the developer to a predetermined image carrier while rotating in a predetermined direction;
The developer carrying member is disposed opposite to the developer carrying member so as to form a predetermined regulation gap with the developer carrying member, and a magnetic path is formed between the developer carrying member and the developer carrying member. A first regulating member made of a magnetic material that magnetically regulates the layer thickness of the developer on the body;
A second magnet disposed on the upstream side of the first restricting member as viewed from the rotation direction of the developer carrier, and having a magnetic pole having the same polarity as the first magnet;
The developer carrier is positioned upstream from the second magnet as viewed from the rotation direction, and is set to gradually separate from the developer carrier as it goes upstream in the rotation direction, A second regulating member having a conveyance amount regulating surface for regulating the amount of the developer conveyed to the first regulating member,
The first regulating member includes an upstream surface facing the upstream side when viewed from the rotation direction of the developer carrying member, and a layer thickness regulating surface that regulates the layer thickness of the developer facing the developer carrying member. And the second magnet is joined to the upstream surface, and the second regulating member is joined to the upstream surface of the second magnet,
The second restricting member is joined to the upstream surface of the second magnet and has a base end portion having a portion closest to the developer carrier, and a main body extending from the base end portion toward the upstream side in the rotation direction. A conveyance amount regulating surface is formed on the main body,
The transport amount regulating surface forms a predetermined angle on the side closer to the developer carrying member with respect to the layer thickness regulating surface, so that the amount between the carrying amount regulating surface and the outer peripheral surface of the developer carrying member is between The space is narrowed toward the downstream side in the rotation direction, and the space is narrowed by the developer that the magnetic field generated between the first magnet and the first restricting member reaches, and the narrowed portion. space der accommodating a developer to be pushed back to the upstream side of the rotational direction by is,
The second magnet generates a magnetic field that increases a magnetic flux density of a magnetic field generated between the first regulating member and the first magnet, and the second magnet is opposed to the developer carrier. It has a surface, and the layer thickness regulating surface the facing surface and is it is configured such that the state of substantially flush developing device. The developing device according to claim 1 , wherein the second restricting member is formed of a nonmagnetic material. An image carrier on which a toner image is formed;
A developing device for supplying toner to the image carrier and forming the toner image on the image carrier;
A transfer member for transferring the toner image onto a sheet;
A fixing unit for fixing the toner image on the sheet onto the sheet;
With
An image forming apparatus in which the developing device according to claim 1 is employed as the developing device.

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