JP5115453B2 - Developing device and image forming apparatus - Google Patents

Description

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

  Conventionally, as a developing method in an image forming apparatus using an electrophotographic method, a one-component developing method using only toner as a developer and a two-component developing method using toner and a carrier are known.

  The one-component development system is advantageous in terms of simplification, miniaturization, and cost reduction of the apparatus, but the deterioration of the toner is likely to be accelerated by the strong stress of the regulating part that charges the toner, and the charge acceptability of the toner is reduced. It's easy to do. Further, the toner regulating member and the surface of the toner carrying member are contaminated with the toner and the external additive, whereby the charge imparting property to the toner is also lowered, and as a result, the life of the developing device is shortened.

  In the two-component development method, the toner is charged by frictional charging by mixing with a carrier, so that the stress is small and it is advantageous for the deterioration of the toner. Furthermore, since the carrier surface area is large, it is relatively resistant to contamination by toner and external additives, which is advantageous for extending the service life.

  However, in the two-component development method, when developing the electrostatic latent image on the image carrier, the surface of the image carrier is rubbed with the magnetic brush of the developer, so that a magnetic brush mark may be generated. Furthermore, there is a problem that the carrier easily adheres to the image carrier and causes an image defect.

  As a development method that solves the problem of image defects while having the long-life characteristics of the two-component development method, the two-component developer is supported on the developer carrier, and only the toner from the two-component developer is changed to the toner carrier. A so-called hybrid development system that is supplied and used for development is disclosed (see Patent Document 1).

  In the hybrid development system, a bias voltage is applied between the toner carrier and the developer carrier, and only the toner is moved to the toner carrier, and only the toner is transferred from the toner carrier to the latent image on the photosensitive member. I'm flying. However, as the speed of image formation increases, it becomes difficult to fly the toner sufficiently, and a decrease in the density of the toner image has become a problem.

  In order to cope with such problems, by providing a plurality of toner carriers, even when the photosensitive member is rotated at a high speed, the toner image is caused to fly a plurality of times, thereby reducing the density of the toner image accompanying the increase in speed. A suppressed image forming apparatus is disclosed (see Patent Document 2).

As disclosed in Patent Document 2, when toner is supplied from a single developer carrier to a plurality of toner carriers, there is a problem that the toner supply to the downstream toner carrier is insufficient. Therefore, in Patent Document 2, a method of increasing the voltage applied to the downstream toner carrier than the voltage applied to the upstream toner carrier, or the surface resistance value of the toner carrier downstream from the upstream side is reduced. A method for increasing the number of rotations of the toner carrier on the downstream side from the upstream side is disclosed.
JP-A-5-150636 JP 2005-37523 A

  However, in the method disclosed in Patent Document 2, since the setting of conditions such as the voltage, rotation speed, and surface resistance value of the toner carrier is different between the upstream side and the downstream side, the stability of the development conditions is reduced, Problems such as a reduction in the recovery rate of the toner remaining on the surface of the toner carrier after development occur.

  The present invention has been made in view of the above problems. Even when a plurality of toner carriers are set under the same conditions and the photosensitive member is rotated at a high speed, the toner is sufficiently supplied to each toner carrier, It is an object of the present invention to provide a developing device and an image forming apparatus that can obtain an image of high quality.

  In order to solve the above problems, the present invention has the following characteristics.

1. A plurality of toner carriers for holding and transporting toner on the outer periphery and developing the electrostatic latent image formed on the image carrier;
A developer carrier that holds and conveys the developer including the toner and the carrier on an outer peripheral portion, and supplies the toner from each toner supply region to a plurality of toner carriers disposed at opposing positions;
A developing device comprising:
A developing device, comprising: a disturbing means for disturbing a surface layer and a lower layer of the developer that is held and moved by the developer carrier between the plurality of toner supply regions.

2. The disturbance means is
2. The developing device according to claim 1, further comprising a disturbing member disposed so that at least a part of the developer held on the developer carrying member moving between the toner supply regions is in contact with the developer.

3. The disturbance member is
3. The developing device according to 2, wherein the developing device has a relative speed difference with the developer held on the developer carrier that moves between the toner supply regions.

4). The disturbance means is
Any one of 1 to 3 above, wherein a magnetic field is generated toward the developer held by the developer carrier that moves between the toner supply regions from a position facing the developer carrier. 2. The developing device according to item 1.

5. The disturbance means is
5. The developing device according to item 4, wherein the magnetic field that changes periodically is generated.

6). The disturbance means is
6. The developing device according to any one of 1 to 5, wherein an electric field is formed toward the developer held on the developer carrier that moves between the toner supply regions.

  7). The average value of the potential of the disturbance means is equal to the average value of the potential of the developer carrier, or a potential that forms an electric field for moving the toner from the developer carrier to the electrode member of the disturbance means. The developing device as described in 6 above, wherein

  8). 8. The developing device according to 6 or 7, wherein the electric field is an alternating electric field.

  9. 9. The developing device according to claim 1, wherein a portion of the disturbing unit facing the developer is disposed at a position facing a magnetic pole of the developer carrying member.

  10. An image forming apparatus comprising: the developing device according to any one of 1 to 9; and the image carrier.

  According to the present invention, the disturbance means for disturbing the surface layer and the lower layer of the developer that is held and moved by the developer carrier between the plurality of toner supply regions is provided, so that the lower layer toner is moved to the surface layer. be able to. As a result, a developing device and an image that can sufficiently supply toner to each toner carrier and obtain a high-quality image even when the photosensitive member is rotated at a high speed while setting a plurality of toner carriers under the same conditions. A forming apparatus can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

(Configuration and operation of image forming apparatus)
FIG. 1 shows a configuration example of a main part of an image forming apparatus according to an embodiment of the present invention. The schematic configuration and operation of the image forming apparatus will be described with reference to FIG.

  The image forming apparatus is a printer that performs image formation by transferring a toner image formed on an image carrier (photosensitive member) 1 to a transfer medium P such as paper by an electrophotographic method.

  The image forming apparatus includes an image carrier 1 for carrying an image. Around the image carrier 1, a charging member 3 for charging the image carrier 1 and an image carrier 1 are provided. A developing device 2 for developing an electrostatic latent image, a transfer roller 4 for transferring a toner image on the image carrier 1, and a cleaning blade 5 for removing residual toner on the image carrier 1 are provided on the image carrier 1. They are arranged in order along the rotation direction A.

  The image carrier 1 is charged by the charging member 3 and then exposed by an exposure device 6 equipped with a laser emitter and the like, and an electrostatic latent image is formed on the surface thereof. The developing device 2 develops the electrostatic latent image to form a toner image. The transfer roller 4 transfers the toner image on the image carrier 1 to the transfer medium P, and then discharges it in the direction of arrow C in the figure. The cleaning blade 5 removes the residual toner on the image carrier 1 after the transfer with a mechanical force.

  The image carrier 1, the charging member 3, the exposure device 6, the transfer roller 4, the cleaning blade 5 and the like used in the image forming apparatus may arbitrarily use a known electrophotographic technique. For example, although a charging roller is shown as the charging member 3 in the figure, a charging device that is not in contact with the image carrier 1 may be used. For example, the cleaning blade 5 may not be provided.

  Next, a configuration example of the developing device 2 of the hybrid developing system according to the present embodiment will be described with reference to FIGS. 1 and 2.

  The main components of the developing device 2 are a developer tank 16, a developer carrier 11, a first toner carrier 25, a second toner carrier 26, and a disturbing means 30.

  FIG. 2 is an enlarged cross-sectional view of some of the main components of the developing device 2 shown in FIG. The developing device 2 shown in FIG. 1 will be described below with reference to FIG.

  The developer tank 16 contains a developer 24 including toner 23 and a carrier.

  The casing 19 is provided with a replenishing portion 14 for replenishing the developer tank 16 with the toner 23 consumed in the first developing area 8 and the second developing area 12. The toner 23 is sent from a hopper (not shown) containing the toner 23 and supplied from the supply unit 14 into the developer tank 16. The replenishment of the toner 23 is controlled based on the output of the ATDC sensor 20 (Automatic Toner Density Control) for toner density detection.

  Inside the casing 19, mixing stirring members 17 and 18 are provided. The mixing and agitating members 17 and 18 mix and agitate the developer 24 to frictionally charge it, and supply the developer 24 to the developer carrier 11.

  The developer carrier 11 includes a magnet body 28 that is fixedly arranged and a rotatable sleeve roller 29 that encloses the magnet body 28. During image formation, the first toner carrier 25 and the second toner carrier 26 are formed. A toner supply bias voltage for supplying the toner 23 to the toner is applied by the developer carrier bias power source 32.

  The developer 24 supplied to the developer carrier 11 is held on the surface side of the sleeve roller 29 by the magnetic force of the magnet body 28 and rotates together with the sleeve roller 29. The regulating member 15 is arranged at a position facing the sleeve roller 29 and regulates the developer 24 held on the surface side of the sleeve roller 29 to a predetermined amount.

  The magnet body 28 has seven magnetic poles S3, N1, S1, N2, N3, S2, and N4 along the rotation direction of the sleeve roller 29 as shown in FIG. Of these magnetic poles, N4 is at the position of the first toner supply region E facing the first toner carrier 25, and N1 is the second toner supply region G facing the second toner carrier 26. It is arranged at the position.

  Further, N2 and N3 are arranged on the side of the mixing and agitating member 17 in order to generate a repulsive magnetic field for separating the developer 24 on the sleeve roller 29.

  The first toner carrier 25 is disposed on the upstream side of the second toner carrier 25, holds the toner 23 on the outer periphery thereof, conveys the toner 23, and flies the toner 23 onto the image carrier 1. The formed electrostatic latent image is developed.

  The toner carrier bias power supply 31 supplies a developing bias voltage to the first toner carrier 25 and the second toner carrier 26. The developer carrier bias power supply 32 supplies a toner supply bias voltage to the sleeve roller 29 of the developer carrier 11.

  In the developing device 2 of the present embodiment, a two-component developer composed of toner 23 and a carrier is used, and the toner 23 is charged with a negative polarity and the carrier is charged with a positive polarity by frictional contact with each other. It shall be. Further, the outer peripheral surface of the image carrier 1 is negatively charged (for example, −500 V), and toner is attached to a portion where the potential is attenuated by exposure (for example, −50 V), and development is performed. In this case, for example, the developing bias voltage is set to -300V, and the toner supply bias voltage is set to -350 to -650V.

  As described above, the first toner carrier 25, the second toner carrier 26, and the sleeve roller 29 are applied with a voltage so that the first toner carrier 11 and the first toner carrier 25 are connected to each other. In the toner supply area E, an electric field for attracting the negatively charged toner from the developer carrier 11 toward the first toner carrier 25 is formed. In the second toner supply region G between the developer carrier 11 and the second toner carrier 26, the electric field that attracts the toner 23 from the developer carrier 11 toward the second toner carrier 26. Is formed.

  The first toner carrier 25 and the second toner carrier 26 may be made of any material as long as the voltage can be applied. Examples thereof include an aluminum roller that has been subjected to a surface treatment such as alumite. In addition, on a conductive substrate such as aluminum, rubber such as polyester resin, polycarbonate resin, acrylic resin, polyethylene resin, polypropylene resin, urethane resin, polyamide resin, polyimide resin, porsulfone resin, polyetherketone resin, vinyl chloride resin, etc. You may use what gave the coating. Moreover, you may use what gave resin coatings, such as a vinyl acetate resin, a silicone resin, a fluororesin, and rubber coatings, such as silicone rubber, urethane rubber, nitrile rubber, natural rubber, and isoprene rubber. The coating material is not limited to these.

  Further, a conductive agent may be added to the bulk or surface of the coating. Examples of the conductive agent include an electronic conductive agent or an ionic conductive agent. Examples of the electronic conductive agent include carbon black such as kettin black, acetylene black, and furnace black, metal powder, and metal oxide fine particles, but are not limited thereto. Examples of the ionic conductive agent include cationic compounds such as quaternary ammonium salts, amphoteric compounds, and other ionic polymer materials, but they are not particularly limited. Furthermore, a conductive roller made of a metal material such as aluminum may be used.

  The disturbance means 30 is disposed between the first toner supply region E and the second toner supply region G, and the developer carrier between the first toner supply region E and the second toner supply region G. The surface layer and the lower layer of the developer 24 held and moved by the 11 sleeve rollers 29 are disturbed. The disturbing means 30 will be described in detail later.

  Next, the operation of the developing device 2 will be described.

  The developer 24 in the developer tank 16 is mixed and stirred by the rotation of the mixing and stirring members 17 and 18 and is frictionally charged. At the same time, it is circulated and conveyed in the developer tank and supplied to the sleeve roller 29 on the surface of the developer carrier 11. Is done. The developer 24 is held on the surface side of the sleeve roller 29 by the magnetic force of the magnet roller 28 inside the toner supply developer carrier 11, and rotates with the sleeve roller 29 so as to face the developing roller 11. The passage amount is regulated by the regulating member 15.

  The developer 24 that passes through the regulating member 15 and is held on the surface side of the sleeve roller 29 moves to the first toner supply region E that faces the first toner carrier 25 as the sleeve roller 29 rotates. Be transported. In the first toner supply region E, developer spikes are formed by the magnetic force of the main magnetic pole N 4 of the magnet body 28, and the developer bias voltage applied to the first toner carrier 25 and the developer carrier 11 are applied. The toner 23 in the developer 24 is supplied to the first toner carrier 25 side by the force applied to the toner 23 by the electric field formed by the toner supply bias voltage.

  The toner 23 supplied to the first toner carrier 25 is conveyed to the first development area 8 as the first toner carrier 25 rotates, and the development bias voltage and the latent image potential on the image carrier are The electrostatic latent image is developed into a visible image by the electric field formed by. The development method may be a reversal development method or a regular development method.

  The toner 23 on the surface of the first toner carrier 25 that has consumed toner in the first development area 8 is conveyed to the first collection area F as the first toner carrier 25 rotates. In the first collection area F, the undeveloped toner 23 remaining on the first toner carrier 25 is collected from the first toner carrier 25 to the developer carrier 11. The undeveloped toner 23 has an electrostatic force generated by an electric field formed by a voltage applied to the first toner carrier 25 and a voltage applied to the developer carrier 11 and an electric field formed by a counter charge of the developer. Then, the developer carrier 11 moves from the first toner carrier 25 to the surface of the sleeve roller 29 by the mechanical rubbing force of the developer spiked by the magnetic force of the main magnetic pole N4 of the developer carrier 11.

  The developer 24 containing the toner 23 collected on the surface of the sleeve roller 29 is opposed to the second toner carrier 26 with the rotation of the sleeve roller 29 after the surface layer and the lower layer are disturbed by the disturbing means 30. The toner is conveyed to the second toner supply region G.

  In the second toner supply region G, developer spikes are formed by the magnetic force of the main magnetic pole N 1 of the magnet body 28, and the developer bias voltage applied to the second toner carrier 26 and the developer carrier 11 are applied. The toner in the developer is supplied to the second toner carrier 26 side by the force applied to the toner by the electric field formed by the toner supply bias voltage.

  The toner layer supplied to the second toner carrier 26 is transported to the second development region 12 as the second toner carrier 26 rotates, and the second development is performed. The toner layer on the surface of the second toner carrier 26 that has consumed toner in the second development region 12 is conveyed to the second recovery region H, and is transferred from the second toner carrier 26 to the developer carrier 11. Collected.

  The collected developer 24 rotates and moves together with the sleeve roller 29 of the developer carrier 11 and is conveyed toward the developer tank 16, and the developer carrier is repelled by the repulsive magnetic fields of the same pole portions N2 and N3 of the magnet body 28. 11 is peeled off from above and collected into the developer tank 16. When a supply control unit (not shown) provided in the supply unit 14 detects from the output value of the ATDC sensor 20 that the toner concentration in the developer 24 has become equal to or lower than the minimum toner concentration for ensuring image density, it is not shown. The toner 23 stored in the hopper is supplied into the developer tank 16 through the toner supply unit 14 by the toner supply means.

  The description of the developing device 2 has been described above.

  FIG. 3 is an explanatory diagram for explaining the state of the developer 24 held on the surface of the sleeve roller 29. The effect of the disturbance means 30 is demonstrated using FIG.

  FIG. 3A shows a state in which the toner 23 is attached to the surface of the carrier 80 in the developer 24, and FIG. 3B shows a state in which the toner 23 has moved from the carrier 80 on the surface layer of the developer 24.

  As shown in FIG. 3A, the developer 24 on the developer carrier 11 is disposed on the upstream side of the first toner supply region E with the toner 23 attached to the surface of the carrier 80. A magnetic brush is formed by a magnetic field. However, since the toner 23 in the developer 24 moves to the first toner carrier 25 in the first toner supply region E, the toner density on the surface layer of the developer carrier 11 is shown in FIG. Is in a lowered state.

  In addition, a counter charge due to the movement of the toner 23 remains in the developer 24. For this reason, in the second toner supply region G, the amount of toner that can move on the developer carrier 11 is small, and the supply electric field is weakened by the counter charge, so that the toner supply property to the second toner carrier 26 is improved. It has dropped significantly.

  Disturbing means 30 disposed in front of the second toner supply region G disturbs the separated toner 23 and carrier 80 on the developer carrier 11 and digs up the lower toner 23 from the surface of the sleeve roller 29. Thus, the toner 23 is adhered to the surface of the carrier 80. Further, the disturbing means 30 disturbs the carrier 80, thereby promoting the contact between the carrier 80 and the sleeve roller 29 and eliminating the counter charge of the carrier 23.

  As described above, since the toner 23 adheres to the surface of the surface carrier 80 and the counter charge of the carrier 80 is removed by the disturbance means 30, sufficient toner can be supplied to the second toner carrier 26. .

  Next, an embodiment of the disturbance means 30 will be described.

  The disturbing means 30 disturbs the developer 24 on the developer carrier 11 by applying an external force to the developer 24. As the external force, a magnetic force, an electrostatic force, or the like can be used in addition to a shearing force generated when the disturbing unit 30 comes into contact with the developer 24 rotating together with the sleeve roller 29.

  The example of the disturbance means 30 is demonstrated using FIGS. 4 to 8 show only the disturbing means 30, the developer carrier 11, and the developer 24 from FIG. 2 for the sake of simplicity, and the first toner carrier 25 and the second toner carrier are not shown. It is assumed that the toner carrier 26 is disposed at the same position as in FIG.

  FIG. 4 is a diagram illustrating an example in which the disturbance member 30 disposed so as to be in contact with the developer 24 is used as the disturbance means 30. The disturbance plate 300, the wire 301, and the roller 302, which are disturbance members, are disposed between the first toner supply region E and the second toner supply region G.

  The disturbance plate 300 in FIG. 4A is a plate-like member such as a blade, and the wire 301 in FIG. 4B is a linear or rod-like member. When the disturbance plate 300 and the wire 301 come into contact with the moving developer 24, a shearing force acts on the developer 24, and the surface layer and the lower layer developer 24 can be disturbed. The example of the disturbance plate 300 and the wire 301 is simple in configuration and can be configured in a small size, so that the degree of freedom in arrangement is large.

  In addition, if the part of the disturbance plate 300 that comes into contact with the developer 24 has a comb shape or a brush shape, the effect of further disturbing the developer 24 can be obtained. Further, by providing drive means for driving the disturbance plate 300 and vibrating the disturbance plate 300, an effect of further disturbing the developer 24 can be obtained.

  FIG. 4C shows an example in which the disturbance unit 30 uses a roller 302 as a disturbance member and a drive unit (not shown) that rotationally drives the roller 302. The rotation direction of the roller 302 may be the same direction as the developer carrier 11 or the reverse direction as indicated by the arrow D. When a rotating member such as the roller 302 is used, the developer 24 is less likely to be clogged than when a fixed member is used.

  The relative speed difference between the sleeve roller 29 and the roller 302 is preferably increased in order to obtain the effect of shearing force, but if it is too large, the developer 24 may be deteriorated or scattered. Therefore, the rotational speed of the roller 302 / the rotational speed of the sleeve roller 29 is preferably about 0 to 2. The roller 302 may not be provided with a driving device and may be driven by the rotation of the developer carrier.

  The material for forming the disturbance plate 300, the wire 301, and the roller 302 is not particularly limited, and various metals, plastic materials, and the like can be used.

  The disturbing means 30 is preferably arranged at a position where it contacts the developer 24 as much as possible, but the distance between the disturbing means 30 and the developer carrier 11 is 0. 0 to prevent the developer 24 from clogging. It is desirable to be 2 mm or more.

  FIG. 5 is a diagram illustrating an example in which the magnet 303 disposed so as to be in contact with the developer 24 is used as the disturbing unit 30. The magnet 303 as a disturbing member is disposed between the first toner supply region E and the second toner supply region G.

  As shown in FIG. 5, the magnet 303 is in contact with the developer 24 at a position facing the magnetic pole S3 of the developer carrier 11 between the first toner supply region E and the second toner supply region G. Has been placed. The polarity of the magnet 303 may be the same as or opposite to the opposite magnetic pole as long as the developer is not clogged. The magnet 303 generates a magnetic field toward the developer 24, disturbs the lines of magnetic force from the magnetic pole N3 acting on the carrier 80 of the developer 24, and disturbs the developer 24. Further, since the magnet 303 is disposed at a position in contact with the developer 24 and disturbs the developer 24 by a shearing force, an effect of disturbing the developer 24 is further obtained.

  FIG. 6 is a diagram illustrating an example in which the magnetic field generated by the disturbing unit 30 is changed. The magnetic coil 304 and the roller 305 are disposed between the first toner supply region E and the second toner supply region G.

  FIG. 6A shows an example in which the disturbance means 30 including the magnetic coil 304 and the drive circuit 40 is used. The magnetic coil 304 is applied with a current or a voltage by the drive circuit 40 and generates a magnetic field. The magnetic force generated by the magnetic coil 304 forms a magnetic field with the magnetic pole S3 of the developer carrier 11, and moves the carrier 80 in the developer 24. When the drive circuit 40 periodically turns on or off the current or voltage applied to the magnetic coil 304, the effect of further disturbing the carrier 80 in the developer 24 is obtained.

  In the example of FIG. 6A, since the magnetic coil 304 can be disposed in non-contact with the developer 24, deterioration due to the disturbance means 30 coming into contact with the developer 24 can be suppressed.

  FIG. 6B shows an example in which the disturbing means 30 is a roller 305 having a magnetic pole and a driving unit (not shown) that drives the roller 305 to rotate. There is no limitation on the number of magnetic poles, and if there is at least one magnetic pole, a magnetic field that changes with the magnetic poles of the developer carrying member 11 is formed, so that disturbance of carriers in the developer can be promoted. The rotational speed of the roller 305 may not have a speed difference with respect to the rotational speed of the developer carrier 11.

  When a roller having a rotating magnetic pole such as the roller 305 is used, a disturbance effect due to a changing magnetic field can be obtained, and the clogging of the developer 24 can be made less likely to occur than when a fixed member is used.

  7 and 8 are explanatory views showing an example using an electrode member to which a voltage is applied as the disturbing means 30. FIG. The electrode member 306 and the roller electrode 307 shown in FIGS. 7 and 8 are arranged between the first toner supply region E and the second toner supply region G.

  The disturbance means 30 in FIG. 7 includes an electrode member 306 and a disturbance power source 33 that applies a voltage to the electrode member 306. As shown in FIG. 7, the electrode member 306 is disposed in a non-contact manner at a position facing the developer 24 on the developer carrier 11. The material of the electrode member 306 is not particularly limited as long as it is a conductive material. Further, the shape is not particularly limited, such as a plate shape or a rod shape.

  The disturbance power source 33 applies a voltage between the sleeve roller 29 and the electrode member 306 so as to generate an electric field in a direction in which the toner 81 is attracted from the surface of the sleeve roller 29. Due to the generated electric field, the toner 81 contained in the lower layer of the developer 24 held on the surface of the sleeve roller 29 moves to the surface layer, and the developer 24 is disturbed. Further, the carrier 80 having a counter charge moves from the surface layer of the developer 24 to the lower layer, and the developer 24 is disturbed. In this case, since the electrode member 306 and the developer 24 are not in contact with each other, the adhesion / accumulation of the developer 24 on the electrode member 306 is suppressed. Further, since no shearing force is applied to the developer 24, deterioration of the developer 24 can be suppressed.

  In order to move the toner 81, it is desirable that the electric field strength between the electrode member 306 and the developer carrier 11 is 100 V / mm or more. The voltage applied to the electrode member 306 is set according to the distance between the electrode member 306 and the developer carrier 11 so that the electric field strength becomes 100 V / mm or more.

  If sufficient electric field strength is obtained between the electrode member 306 and the developer carrier 11 simply by grounding the electrode member 306 with the voltage applied to the developer carrier 11, the disturbance power source 33 is turned on. It is not necessary to provide it.

  In the example of FIG. 8, an example in which a voltage is applied to the rotating roller electrode 307 will be described.

  8 includes a roller electrode 307, which is a disturbance member, a disturbance power source 41 that applies a voltage to the roller electrode 307, and a drive unit (not shown) that rotates the roller electrode 307 (not shown). .

  The roller electrode 307 is disposed so as to be in contact with the developer 24 on the developer carrier 11 and rotates at the same speed as the sleeve roller 29. The disturbance power supply 41 forms an electric field on the roller electrode 307 that is equal to the average value of the voltage applied to the developer carrier 11 or moves the toner 81 from the developer carrier 11 to the roller electrode 307. Apply a DC voltage. Further, when the voltage applied to the developer carrier 11 is a DC voltage, the disturbance power supply 41 converts an AC voltage that generates an oscillating electric field between the roller electrode 307 and the developer carrier 11 to a DC voltage. Apply by overlapping.

  In general, an AC voltage is applied to the developer carrier 11, and in this case, an oscillating electric field is formed even if only the DC voltage is applied to the roller electrode 307. In general, a voltage in the direction of supplying toner to the first toner carrier 25 and the second toner carrier 26 is applied to the developer carrier 11, so that the disturbance power source 4 is not provided and the roller electrode 307 is provided. The same effect can be obtained by grounding or simply setting the same potential as that of the first toner carrier 25 and the second toner carrier 26.

  The roller electrode 307 is not particularly limited as long as it has conductivity, and the same material as the toner carrier 11 can be used. In addition, the roller electrode 307 is an example of an electrode member, and the electric field similar to the above may be formed by using a conductive disturbance plate 300, a wire 301, a roller 302, a magnet 303, and the like.

  When the oscillating electric field is thus formed, the toner 81 moves between the electrode members even at the same potential. Since the toner 81 is moved by the oscillating electric field, the effect of digging the toner 81 from the lower layer of the developer 24 held by the sleeve roller 29 is further enhanced. Further, if there is a potential difference, the movement of the carrier 80 having a counter charge is also added, which is more effective. When the rotating roller electrode 307 is used, the developer 24 is less likely to be clogged than when a fixed member is used. Further, it is possible to prevent clogging in the same manner even if the roller electrode 307 is not provided with a driving device and is driven by the rotation of the developer carrier 11.

  In order to prevent leakage with the developer carrier 11, it is desirable to apply a voltage so that the electric field strength between the roller electrode 307 and the developer carrier 11 is 10000 V / mm or less.

  As described above, according to the present invention, even when a plurality of toner carriers are set to the same condition and the photosensitive member is rotated at a high speed, a sufficient amount of toner is supplied to each toner carrier, so that a high-quality image is obtained. A developing device and an image forming apparatus can be provided.

1 is a cross-sectional view illustrating a configuration example of a main part of a developing device 2 and an image forming apparatus including the same according to an embodiment of the present invention. 3 is an enlarged cross-sectional view of some of main components of the developing device 2. FIG. FIG. 6 is an explanatory diagram for explaining a state of a developer 24 held on a surface of a sleeve roller 29. FIG. 6 is an explanatory diagram showing an example in which a member arranged so as to come into contact with the developer 24 is used as a disturbance means 30. 4 is an explanatory diagram showing an example in which a magnet 303 arranged so as to come into contact with the developer 24 is used as a disturbing means 30. FIG. It is explanatory drawing which shows the example which changes the magnetic force line which the disturbance means 30 generate | occur | produces. It is explanatory drawing which shows an example using the electrode member which applied the voltage as the disturbance means. It is explanatory drawing which shows the other example using the electrode member which applied the voltage as the disturbance means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image carrier 2 Developing device 3 Charging member 4 Transfer roller 5 Cleaning blade 6 Exposure device 11 Developer carrier 12 Sleeve roller 13 Magnet body 16 Developer tank 17, 18 Mixing stirring member 20 ATDC sensor 23 Toner 24 Developer 25 First 1 toner carrier 26 second toner carrier 28 magnet 29 sleeve roller 30 disturbance means 31 bias power source for toner carrier 32 bias power source for developer carrier 33, 42 power source for disturbance 80 carrier E first toner supply Area F First collection area G Second toner supply area H Second collection area

Claims (10)

A plurality of toner carriers for holding and transporting toner on the outer periphery and developing the electrostatic latent image formed on the image carrier;
A developer carrier that holds and conveys the developer including the toner and the carrier on an outer peripheral portion, and supplies the toner from each toner supply region to a plurality of toner carriers disposed at opposing positions;
A developing device comprising:
A developing device, comprising: a disturbing means for disturbing a surface layer and a lower layer of the developer that is held and moved by the developer carrier between the plurality of toner supply regions. The disturbance means is
2. The developing device according to claim 1, further comprising a disturbing member disposed so that at least a part of the developer is held on the developer carrying member that moves between the toner supply regions. . The disturbance member is
The developing device according to claim 2, wherein the developing device has a relative speed difference with the developer held on the developer carrier that moves between the toner supply regions. The disturbance means is
4. The magnetic field is generated toward the developer held by the developer carrier that moves between the toner supply regions from a position facing the developer carrier. 5. The developing device according to claim 1. The disturbance means is
The developing device according to claim 4, wherein the magnetic field that changes periodically is generated. The disturbance means is
6. The developing device according to claim 1, wherein an electric field is formed toward the developer held by the developer carrying member that moves between the toner supply regions. The average value of the potential of the disturbance means is equal to the average value of the potential of the developer carrier, or a potential that forms an electric field for moving the toner from the developer carrier to the electrode member of the disturbance means. The developing device according to claim 6, wherein: The developing device according to claim 6, wherein the electric field is an alternating electric field. 9. The developing device according to claim 1, wherein a portion of the disturbing unit facing the developer is disposed at a position facing a magnetic pole of the developer carrying member. An image forming apparatus comprising: the developing device according to claim 1; and the image carrier.

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