JP2014026119A - Developing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce developer remaining in a rotary feeder while reducing stress on the developer, so as to suppress a reduction in the conveyance amount of the developer.SOLUTION: A developing device 5 according to the present invention includes: a developing unit 50 that develops a latent image on an image carrier; a stirring unit 51 that is provided on the outside of the developing unit, and accommodates a part of developer to stir the developer; a rotary feeder that discharges a fixed amount of the developer in the stirring unit; and a developer conveying unit that conveys the developer discharged from the rotary feeder to the developing unit with the use of air pressure. The developing device 5 further has an air spraying unit that sprays air toward a section formed by a rotor and a stator included in the rotary feeder.

Description

  The present invention relates to a developing device that develops an electrostatic latent image on an image carrier and an image forming apparatus including the developing device, and more particularly to a device that transports a developer using air pressure.

  The developing device is a device that develops and visualizes the electrostatic latent image formed on the latent image carrier using a two-component developer composed of toner and carrier. The developer whose toner has been consumed after completion of the development process in the development area is collected, mixed with the replenished toner, stirred, and again developed. In order to obtain a stable toner image, the developer used in the developing device having such a configuration needs to maintain a constant toner concentration and charge amount. The toner density is adjusted by the amount of toner consumed during development and the amount of replenished toner, and the charge amount is given by frictional charging during mixing of the carrier and toner. That is, in the developing device, the two-component developer is sufficiently agitated to make the toner density distribution uniform and to impart toner charge to stabilize the toner image.

  In a general developing device, toner is dispersed and charged by using the stirring effect of the rotation of two screws during a short time until the replenished toner is pumped up to the developing sleeve. In particular, when the toner balance is large, the replenished toner is not sufficiently dispersed but is drawn up to the developing sleeve, resulting in quality problems such as soiling and toner scattering.

  In order to solve this problem, a separate agitation unit is provided at a location distant from the development unit, the development unit and the agitation unit are connected by a developer circulation means, and the agitation unit performs agitation in accordance with the state of the developer. For example, Patent Documents 1 and 2 propose a developing device that supplies a developer whose density and charge amount are appropriately adjusted to a developing unit.

  In such a developing device, when the amount of developer transported from the developer agitating unit to the developing unit is changed, the amount of developer in the developing unit is changed, which tends to hinder development and the like. . For this reason, as a means for quantitatively transporting the developer from the developer agitating unit toward the developing unit, one using an air flow (air flow) supplied from an air pump is known. When transporting the developer using air, the developer is transported using the pressure (positive pressure) and flow velocity of the air, so the developer supply unit (lower end of the stirring unit) to which the air pump is connected, and stirring A differential pressure is generated in the chamber (atmospheric pressure). Therefore, it is necessary to convey the developer from the agitation chamber to the air conveyance source while shielding the agitation chamber and the developer supply unit in an air flow path. In such a system, a rotary feeder is generally used as a supply device that supplies developer from an agitation chamber to an air conveyance source.

  A general rotary feeder is composed of a rotor having a plurality of rotating blades and a stator that covers the rotor, and is an excellent method of quantitativeness and controllability. However, when transporting the developer using air, the developer is transported using the air pressure (positive pressure) and the flow velocity. Because of the pressure, air flows from the developer supply unit into the rotary feeder (air leak). Further, even if the sealing property between the rotor and the stator is insufficient, air leaks into the rotary feeder. Since the developer in the rotary feeder is supplied to the developer supply section by free fall, the air flow direction of the inflowing air and the direction of the developer falling are in an opposing relationship, and the pressure of the air into which the developer falls inflows. The developer to be dropped in the rotary feeder is not completely dropped and remains. For this reason, there is a problem that the amount of developer supplied from the rotary feeder is reduced.

  Patent Documents 3 and 4 are examples of methods for preventing the developer from remaining in the rotary feeder. Patent Document 3 discloses a configuration in which air from an air supply source is diverted and a part of the air is blown to the downstream side in the rotational direction of the edge of the rotary feeder discharge port. It is intended to prevent intrusion and prevent the return of the granular material, not to blow air into the section formed in the rotary feeder, the developer inside the rotary feeder remains without dropping, It does not lead to the problem that the supply amount of the granular material is reduced.

  Patent Document 4 discloses a configuration in which an impeller that mechanically scrapes a powder in a small chamber formed by a rotor of a rotary feeder and a stator that covers the rotor is provided. However, when this structure is used in a rotary feeder used for transporting a developer, there is a problem in that the developer is stressed by mechanically scraping the developer and causes deterioration of the carrier and toner.

  An object of the present invention is to reduce the developer remaining in the rotary feeder while reducing the stress applied to the developer, and to improve the decrease in the transport amount of the developer.

  In order to achieve the above-described object, a developing unit that develops a latent image on the image carrier, a stirring unit that is provided outside the developing unit and that contains a part of the developer and stirs the developer, and In the developing device including a rotary feeder that discharges the developer in the stirring unit in a fixed amount, and a developer transport unit that transports the developer discharged from the rotary feeder to the developing unit using air pressure, the rotary feeder is: A rotor and a stator that covers the rotor are provided, and an air blowing portion that blows air toward a section formed by the rotor and the stator is provided.

  According to the present invention, the developer is pushed out of the rotary feeder by the pressure of the air, because the air blowing part that blows air toward the section formed by the rotor and the stator of the rotary feeder is mechanically used. The stress on the developer is reduced compared to the one that scrapes off the developer, and the air helps the developer to fall, so that the developer is less likely to remain in the rotary feeder and the developer transport amount is reduced. Can be improved.

1 is a schematic configuration diagram of an image forming apparatus including a developing device according to the present invention. FIG. 2 is a perspective view illustrating one embodiment of a developing device according to the present invention. FIG. 2 is a schematic configuration diagram inside a developing device. The expanded sectional view which shows the structure of a rotary feeder and a developer conveyance part. (a) is an enlarged view which shows the structure which concerns on the 1st Embodiment of this invention, (b) is sectional drawing when the structure shown to (a) is seen from the air supply side. (a) is an enlarged view which shows the structure which concerns on the 2nd Embodiment of this invention, (b) is sectional drawing when the structure shown to (a) is cut | disconnected in the axial direction. (a) is an enlarged view which shows the structure which concerns on the 3rd Embodiment of this invention, (b) is sectional drawing when the structure shown to (a) is cut | disconnected in the axial direction. (a) is an enlarged view which shows the structure which concerns on the 4th Embodiment of this invention, (b) is sectional drawing when the structure shown to (a) is cut | disconnected in the axial direction. The expanded sectional view which shows the structure which concerns on the 5th Embodiment of this invention. An expanded sectional view explaining a subject when a rotor rotates in the state where air was supplied from an air blowing part. (a) is a fragmentary sectional view which shows the structure which concerns on the 6th Embodiment of this invention of this invention, (b) is an expanded sectional view which shows a state when a rotor rotates in the structure shown to (a). Sectional drawing which fractured | ruptured the rotary feeder part which concerns on 6th Embodiment to the axis line walk.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each embodiment, the same reference numerals are assigned to the same members, and duplicate descriptions are omitted. The overall configuration and function of an image forming apparatus including a developing device according to the present invention will be described with reference to FIG. 1, and then the configuration of each embodiment of the developing device will be described.

  As an embodiment, the developing device includes an air flow supply unit, and an air blowing unit that blows air toward a section formed by a rotor and a stator included in the rotary feeder. The form of the part differs in each embodiment. The image forming apparatus to which the developing device according to the present invention is applied is not limited to the image forming apparatus using the four-color developer shown in FIG. 1, but is an image forming apparatus using a single-color developer. Of course it doesn't matter.

  In FIG. 1, the image forming apparatus is exemplified by a color copying machine, but the image forming apparatus is not limited to a color copying machine, and is a printer, facsimile, plotter, or printer, scanner, copying function and facsimile function. It may be a multi-function machine equipped with.

  FIG. 1 shows that a color copying machine as an image forming apparatus corresponds to each color (yellow, magenta, cyan, black) facing the lower surface of an intermediate transfer belt 8 as an unfixed image carrier in an intermediate transfer unit 10. Image forming units 6Y, 6M, 6C, and 6Bk are provided. Each image forming unit has the same structure except that the color of the toner used in the image forming process is different. Each image forming unit includes photosensitive drums 1Y, 1M, 1C, and 1Bk as latent image carriers, charging means (not shown) arranged around each photosensitive drum, developing devices 5Y, 5M, 5C, and 5Bk, The cleaning unit is not shown. In each image forming unit, an image forming process (charging process, exposure process, developing process, transfer process, cleaning process) is performed on each photosensitive drum, and a desired toner image is formed on each photosensitive drum. The

  Each photosensitive drum is rotationally driven in the clockwise direction in the drawing by a driving unit (not shown), and the surface is uniformly charged at the position of the charging means (charging process). Thereafter, the surface of each photosensitive drum reaches the irradiation position of a laser beam emitted from an exposure unit (not shown), and an electrostatic latent image is formed by exposure scanning at this position (exposure process). Thereafter, the surface of each photosensitive drum reaches a position facing each developing device, and the electrostatic latent image at this position is developed to form a desired toner image (developing process). After that, the surface of each photoconductive drum has an endless intermediate transfer belt 8 wound around a plurality of roller members, and a primary transfer bias that is positioned roughly with each photoconductive drum in an inner loop of the intermediate transfer belt 8. The toner image on each photosensitive drum is transferred onto the intermediate transfer belt 8 at the position facing the rollers 9Y, 9M, 9C, 9Bk (primary transfer process). Thereafter, the surface of each photosensitive drum reaches a position facing the cleaning unit, and untransferred toner remaining on the surface is collected at this position (cleaning step). The electric potential of the surface of each photosensitive drum after cleaning is initialized by a neutralizing roller (not shown). Thus, a series of processes performed on each photosensitive drum is completed.

  As shown in FIG. 1, the image forming process described above is performed by each of the four image forming units 6Y, 6M, 6C, and 6Bk. That is, a laser beam based on image information from an exposure unit (optical writing device) (not shown) disposed below each image forming unit is applied to the photosensitive drum 1Y of each image forming unit 6Y, 6M, 6C, 6Bk. Irradiated on 1M, 1C, 1Bk. Thereafter, the toner images of the respective colors formed on the respective photosensitive drums through the developing process are transferred onto the intermediate transfer belt 8 in an overlapping manner. In this way, a color image is formed on the intermediate transfer belt 8. The four primary transfer bias rollers 9Y, 9M, 9C, and 9Bk respectively sandwich the intermediate transfer belt 8 with the photosensitive drums 1Y, 1M, 1C, and 1Bk to form a primary transfer nip. The primary transfer bias rollers 9Y, 9M, 9C, and 9Bk are applied with a transfer bias having a polarity opposite to the polarity of the toner. The intermediate transfer belt 8 travels in the direction of the arrow and sequentially passes through the primary transfer nips of the primary transfer bias rollers 9Y, 9M, 9C, and 9Bk. In this way, the toner images of the respective colors on the photosensitive drums 1Y, 1M, 1C, and 1Bk are primarily transferred while being superimposed on the intermediate transfer belt 8. Thereafter, the intermediate transfer belt 8 onto which the toner images of the respective colors are transferred in a superimposed manner reaches a position facing the secondary transfer roller 19 as a secondary transfer unit. The color toner image formed on the intermediate transfer belt 8 is transferred onto a transfer sheet P as a recording medium conveyed to the position of the secondary transfer nip formed between the secondary transfer roller 19 and the intermediate transfer belt 8. Is done. Thus, a series of processes performed on the intermediate transfer belt 8 is completed.

  A plurality of transfer sheets P are stored in a paper feed unit 26 disposed at the lower part of the image forming apparatus main body 100, and are separated and fed one by one by a paper feed roller 27. The fed transfer paper P is temporarily stopped by the registration roller pair 28, and after the oblique deviation is corrected, it is conveyed toward the secondary transfer nip by the registration roller pair 28 at a predetermined timing. As described above, a desired color image is transferred onto the transfer paper P at the secondary transfer nip.

  The transfer paper P onto which the color image has been transferred at the position of the secondary transfer nip is conveyed to the fixing unit 20, where the color image transferred to the surface is fixed by heat and pressure generated by the fixing roller and the pressure roller. The After the fixing, the transfer paper P is discharged as an output image to the paper discharge unit 30 formed on the upper surface of the apparatus main body 100 by the paper discharge roller pair 29 and stacked. Thus, a series of image forming processes in the image forming apparatus is completed. In FIG. 1, reference numeral 32 denotes a reading unit.

FIG. 2 is a diagram illustrating a basic configuration of a developing device as a developing agitation / circulation system. Since each developing device has the same configuration except that the color of the toner is different, description will be made by omitting Y, M, C, and Bk, which are codes for identifying the color. Each developing device 5 includes a developing unit 50 that develops the electrostatic latent image on each photosensitive drum 1, a stirring unit 51 that performs stirring according to the state of the developer at a position away from the developing unit 50, and a stirring unit. 51, a toner cartridge 52 for replenishing toner as a developer, a rotary feeder 53 provided below the stirring unit 51, and an air pump (air supply source) 54 as an air flow supply means for conveying the developer by air pressure. Etc. In FIG. 1, only the developing unit 50 is shown.
The developing unit 50 and the stirring unit 51 are connected by a circulation path 55, and the rotary feeder 53 and the developing unit 50 are connected by a circulation path 56 and the like. The toner cartridge 52 and the agitation unit agitation unit 51 are connected by a toner supply path 57, and the air pump 54 and the rotary feeder 53 are connected by a pipe line 58. In FIG. 2, reference numeral 59 denotes a motor as a toner replenishment drive source, reference numeral 60 denotes a motor as an agitation drive source, and reference numeral 61 denotes a motor as a drive source of the rotary feeder 53.

  The configuration of the developing unit 50 will be described with reference to FIG. The developing unit 50 is rotatably supported in the casing 62, is transported to the photosensitive drum carrying the developer, and conveying screws 63 and 64 as developer conveying members having spiral fins. And a developing roller 65 as a developer carrying member. The casing 62 contains a two-component developer in which toner and carrier are mixed. The developer is circulated and conveyed in the casing 62 by the conveying screws 63 and 64. The developer is transported from the front side to the back side in the figure by the transport screw 64, and a part of the developer is sucked up by the magnetic force by the developing roller 65 and adsorbed on the surface thereof, and is evenly uniformed by the doctor blade 66. Then, by contacting the photosensitive drum 1, the electrostatic latent image on the photosensitive drum 1 is developed with toner to form a toner image.

  The developed developer is transported to the stirring unit 51 through the circulation path 55 from a discharge port 67 (see FIG. 2) formed at the end of the transport screw 63. A toner detection unit (not shown) is installed on the most downstream side of the conveying screw 63, and toner is supplied from the toner cartridge 52 based on the signal. Toner supply is performed by rotating a screw (not shown) in the toner supply path 57 by the motor 59. Toner replenishment is performed in the circulation path immediately before the entrance of the agitation unit 51. In the stirring unit 51, the developer after development and the replenished toner are mixed to obtain a developer having an appropriate toner concentration and charge amount.

  A developer having an appropriate toner concentration and charge amount by mixing the developer after development and the replenished toner passes through a discharge port 70 formed at the lower portion of the stirring unit 51 as shown in FIG. It falls into the feeder 53.

  The rotary feeder 53 includes a rotor 75 that extends radially and has a plurality of blades 75 </ b> A arranged in the circumferential direction, a stator 76 that covers the rotor 75, and a motor 60 that rotationally drives the rotor 75. The rotary feeder 53, the circulation path 56, and the pipe line 58 are connected by a joint pipe line 77 serving as a developer transport unit. The rotary feeder 53 quantitatively discharges the developer downward by the rotation of the internal rotor 75. The discharged developer is transported and supplied again from the circulation path 56 to the developing unit 50 via the receiving port 68 (see FIG. 2) by the air supplied from the air pump 54. A developer supply port 69 is provided on the upper surface of the stirring unit 51, and a discharge port 70 is provided on the lower surface. The stirrer body 51a that constitutes the stirrer 51 has an inverted conical shape whose diameter decreases toward the discharge 70. A screw 71 that conveys the developer from the bottom to the top is provided in the center of the stirring unit main body 51a, and two rotatable stirring members 72 are provided on the outside thereof. In the stirring unit 51, the developer is stirred and mixed by the rotating operation of these stirring members 72. The screw 71 is directly connected to the motor 60, and the stirring member 72 is connected to the motor 60 via a reduction gear train 73. The developer is transported from the replenishing port 69 of the stirring unit 51 to the discharge port 70 using gravity. Since the developer is always present as a buffer in the stirring unit 51, the unmixed developer is not discharged as it is.

Next, features of the present invention will be described.
(First embodiment)
5 (a) and 5 (b) show characteristic portions of the first embodiment of the present invention. In FIG. 5, the rotor 75 and the stator 76 in the rotary feeder 53 are provided with a clearance between the tip of the blade 75 </ b> A of the rotor 75 and the inner surface of the stator 76. Since the sealing performance between the rotor 75 and the stator 76 is insufficient, the air from the air pump 54 passes through the clearance and leaks to the upper stirring portion 51. Further, in the joint pipe 77, the above-described leaked air generates an upward air flow in the figure, and the developer filled in the rotor 75 falls due to the pressure of the upward air, resulting in a clean phenomenon.

  Therefore, in this embodiment, inside the joint pipe line 77, the air of the air pump 54 is divided into the pipe line 78 and the pipe line 79, and the air flowing through the pipe line 78 serving as a blowing portion is used as the edge of the discharge port 53A of the rotary feeder 53. The rotor 75 is sprayed on the upstream side in the rotation direction. Specifically, one end of the pipe line 78 is opened from the stator 76 into the rotary feeder 53, and the air flowing through the pipe line 78 is made into a space S as a section formed by the adjacent blades 75 </ b> A of the rotor 75 and the stator 76. I try to spray towards the. The developer T inside the space S is dropped to the lower part of the joint pipe 77 and then merges with the air flowing through the pipe 79 in the circulation path 56. That is, the rotary feeder 53 includes a pipe line 78 as an air blowing portion that blows air toward a section formed by the rotor 75 and the stator 76.

In this way, by blowing air into the space S on the upstream side in the rotation direction of the rotary feeder 53, it is possible to ensure a relatively long time to push the developer with respect to the rotation speed of the rotor 75. The developer supply amount can be improved. Further, since the developer T is pushed out of the rotary feeder 53 by the pressure of air, the stress on the developer T is reduced as compared with the case where the developer T is mechanically scraped off, and the air causes the developer T to fall. Since it assists, the developer T is less likely to remain in the rotary feeder 53, and the reduction in the transport amount of the developer T can be improved. From this point of view, the developer drop assisting means is constituted by the air pump 54, the pipe line 58, and the pipe line 78 of the joint pipe line 77.
(Second Embodiment)
FIG. 6A and FIG. 6B show characteristic portions of the second embodiment of the present invention. In this embodiment, the air in the air pump 54 is divided into the pipe 78 and the pipe 79 inside the joint pipe 77, and the air flowing through the pipe 78 serving as a spraying portion is rotated in the rotational direction of the edge of the discharge port 53 </ b> A of the rotary feeder 53. The rotor 75 is sprayed on the upstream side. Further, the joint pipe line 77 is disposed so that air flows in parallel to the axial direction of the rotor 75, and a pipe line 78 serving as an air blowing portion is installed on the air pump 54 side of the joint pipe line 77. Connected.

With such a configuration, the direction in which the developer T inside the rotor 75 is pushed out is parallel to the axial direction of the rotor 75 and is the same direction as the air flow direction of the conduit 79. Therefore, since the developer T is pushed out from the rotary feeder 53 by the pressure of air, the stress on the developer T is reduced as compared with the case where the developer T is mechanically scraped off, and the air causes the developer T to fall. Since it assists, the developer T is less likely to remain in the rotary feeder 53, and the reduction in the transport amount of the developer T can be improved. Further, the extruded developer T can be conveyed relatively smoothly to the circulation path 56.
(Third embodiment)
FIG. 7A and FIG. 7B show characteristic portions of the third embodiment of the present invention. In this embodiment, the pipe 80 is provided in the stator 76 on the upstream side in the rotational direction of the edge of the discharge port 53 </ b> A of the rotary feeder 53, the air from the air pump 54 is divided into the pipe 80 and the pipe 81, and the air flowing through the pipe 80 Was configured to be sprayed onto the rotor 75. That is, one end of the pipe 80 opens from the stator 76 into the rotary feeder 53, and the air flowing through the pipe 80 is directed to the space S as a section formed by the adjacent blade 75 </ b> A of the rotor 75 and the stator 76. I try to spray. Further, the joint pipe line 77 is arranged so that air flows in parallel to the axial direction of the rotor 75, and a pipe line 80 serving as an air blowing portion is arranged on the air pump 54 side of the joint pipe line 77. Connected.

  In the case of this embodiment, the sprayed air drops the developer T in the space S inside the rotor to the lower part of the joint pipe 77 and then merges with the air flowing through the pipe 81 in the circulation path 56.

  In this way, by blowing air into the space S on the upstream side in the rotation direction of the rotary feeder 53, it is possible to ensure a relatively long time to push the developer T against the rotation speed of the rotor 75. The supply amount of the developer from can be improved. Further, since the developer T is pushed out of the rotary feeder 53 by the pressure of air, the stress on the developer T is reduced as compared with the case where the developer T is mechanically scraped off, and the air causes the developer T to fall. Since it assists, the developer T is less likely to remain in the rotary feeder 53, and the reduction in the transport amount of the developer T can be improved. Furthermore, by providing the pipe line 80 in the stator 76, the pipe line 80 can be freely arranged regardless of the dimensions of the joint pipe line 77 and the discharge port 53A of the rotary feeder 53.

Further, since the air from the air pump 54 is configured to flow in parallel to the axial direction of the rotor 75 and the pipe line 80 is installed on the pipe line 58 side on the circumferential surface of the stator 53, the developer inside the rotor 75 is removed. The direction of extrusion is parallel to the axial direction of the rotor 75 and is the same direction as the air flow direction of the pipe 81. Therefore, the extruded developer T can be conveyed relatively smoothly to the circulation path 56.
(Fourth embodiment)
8 (a) and 8 (b) show the characteristic part of the fourth embodiment of the present invention. In this embodiment, in the pipe line 58, the air of the air pump 54 is divided into the pipe line 81 and the pipe line 82, and the air flowing through the pipe line 82 serving as the air blowing portion is rotated in the rotation direction of the edge of the discharge port 53 </ b> A of the rotary feeder 53. The rotor 75 (in the space S) is blown on the upstream side.

  In the case of this embodiment, the sprayed air drops the developer inside the rotor to the lower part of the joint pipe line 77 and then merges with the air flowing through the pipe line 81 in the circulation path 56. In addition, the other end 82b of the pipe line 82 is connected to the wall surface of the joint pipe line 77, and the cross-sectional shape of the tip 82a of the pipe line 82 that is close to the blade 75A of the rotor 75 can be variously round or polygonal. It may be formed in a simple cross-sectional shape. Also in this embodiment, the joint pipe line 77 is arranged so that air flows in parallel to the axial direction of the rotor 75, and a pipe line 82 serving as an air blowing portion is provided closer to the air pump 54 than the joint pipe line 77. Placed and connected.

With such a configuration, air is blown to the rotor 75 (in the space S) on the upstream side in the rotation direction of the rotary feeder 53, and the time for extruding the developer T with respect to the rotation speed of the rotor 75 is secured relatively long. The developer supply amount from the rotary feeder 53 can be improved. In addition, the air from the air pump 54 is configured to flow in parallel to the axial direction of the rotor 75, and further, a pipe 82 is connected to the pipe 58 side and installed. With such a configuration, the direction in which the developer T inside the rotor 75 is pushed out is parallel to the axial direction of the rotor 75 and is the same direction as the air flow direction of the pipe 81. Therefore, the pushed developer T can be conveyed relatively smoothly to the circulation path 56. Further, since the developer T is pushed out from the rotary feeder 53 by the pressure of air, the stress on the developer T is reduced as compared with the case where the developer T is mechanically scraped off.
(Fifth embodiment)
FIG. 9A and FIG. 9B show characteristic portions of the fifth embodiment of the present invention. In this embodiment, the rotary feeder 53 is located near the edge 53B on the downstream side in the rotation direction of the rotor 75 in the rotary feeder 53 of the discharge port 53A that communicates with the joint pipe line 77, and the rotor 53 with respect to the edge 53B. An air blowing portion 83 that blows air toward the space S formed by the blades 75 adjacent to the rotor 75 of the rotary feeder 53 and the stator 76 that covers the rotor 75 is provided on the downstream side in the rotational direction of 75. . In this embodiment, the air blown from the air blowing unit 83 to the space S of the rotary feeder 53 divides the air from the air pump 54 used for transporting the developer.

  When the rotor 75 in the rotary feeder 53 rotates during the developer circulation, the developer is discharged from the air blowing portion 83 to the rotary feeder 53 in a state where the developer is discharged to the joint pipe line 77 below the rotary feeder 53. The developer T in the rotary feeder 53 is conveyed to the discharge port 53A of the rotary feeder 53 by the air blown from the air blowing portion 83 by blowing the air toward the space S in which the developer T is inside. It is. Thereby, it is possible to prevent the developer T from remaining in the rotary feeder 53, and the amount of developer T discharged from the rotary feeder 53 to the joint pipe line 77 below the rotary feeder 53 is improved. A decrease in the transport amount can be prevented. Further, since the residual of the developer T in the rotary feeder 53 is eliminated by the air blowing, the stress on the developer T is reduced as compared with the case where the developer T is mechanically scraped off, and the carrier and toner Cause less deterioration.

By the way, in the state where the rotor 75 in the rotary feeder 53 rotates and the developer T is discharged to the joint pipe line 77 below the rotary feeder 53, the rotor 75 is always downstream in the rotation direction toward the space S. When air is blown from the air blowing portion 83 provided on the rotor 75, the blade 75A of the rotor 75 that forms the space S by the rotation of the rotor 75 is positioned upstream in the rotation direction of the rotor 75 as shown in FIG. The blade 75A2 to be moved is close to the edge 53B on the downstream side in the rotation direction of the rotor 75 in the rotary feeder 53 of the discharge port 53A communicating with the joint pipe line 77 below the rotary feeder 53, and the rotary of the opening S1 in the space The area opened to the discharge port 53A of the feeder 53 is reduced. As a result, the flow of air blowing from the air blowing portion 83 toward the space S in the direction of the discharge port 53A is impeded, and the air returns to the space 75 by hitting the blade 75A1 on the upstream side in the rotation direction of the rotor 75. Due to movement or the like, the developer T remaining in the rotary feeder 53 cannot be transported to the discharge port 53A, and as a result, the developer may remain in the rotary feeder 53.
(Sixth embodiment)
Therefore, in the sixth embodiment of the present invention, the start timing and stop timing of air blowing from the air blowing portion 83 are performed in accordance with the rotation of the rotor 75 of the rotary feeder 53.

  As a specific embodiment, as shown in FIGS. 11A and 11B, an air pump 84 as an air supply source of air blown out from the air blowing portion 83 is separated from the air pump 54 for conveying the developer. The air pump 54 and the air blowing unit 83 are connected to each other via a pipe 85. The pipe 85 is provided with an openable / closable valve 86 such as an electromagnetic valve. In this embodiment, in order to detect the displacement of the blade 75 </ b> A due to the rotation of the rotor 75, rotor position detection means is provided. The rotor position detection means can be configured by combining an encoder slit plate 87 provided so as to rotate integrally with the rotor 75 and a detection sensor 88 (for example, a photo interrupter) that detects the encoder slit plate 87. In this embodiment, an encoder slit plate 87 is provided on a shaft 89 that rotatably supports the rotor 75 so as to be integrally rotatable, and within the rotational movement range of the encoder slit plate 87 on the side plate 90 of the rotary feeder 53 that supports the shaft 89. A detection sensor 88 is attached and arranged.

  Regarding the positional relationship between the blade 75A of the rotor 75, the opening 83a of the air blowing portion 83, and the discharge port 53A of the rotary feeder, the shape of the blade 75A of the rotor 75 such as the number, angle, thickness, etc. Detection is possible by configuring the slits of the encoder slit plate 87 from the relationship with the arrangement position of the feeder discharge port 53A in the rotor rotation direction.

  The air pump 84, the detection sensor 88, and the on-off valve 86 are connected to the control means 100 by a signal line. The control means 100 is constituted by a computer, and controls the opening / closing operation of the opening / closing valve 86 and the operation of the air pump 84 based on the position information of the blade 75A detected by the detection sensor 88.

  In this embodiment, the control means 100 is a position where the blade 75A2 on the downstream side in the rotation direction of the rotor 75 among the blades 75 of the rotor 75 forming the space S of the rotary feeder 53 has passed the opening 83a of the air blowing unit 83. Then, the air pump 84 is actuated to start blowing air, and the area opened to the discharge port 53A of the rotary feeder of the opening Sa of the space S is at a position where it is 1/3 or less of the total opening area. Of the blades of the rotor 75 forming the space S, when the blade 75A1 on the upstream side in the rotation direction of the rotor 75 arrives, the operation of the air pump 84 is stopped and the blowing of air is stopped.

  As shown in FIG. 11 (a), the rotor 75 rotates, and among the blades 75 A of the rotor 75 that forms the space S, the blade 75 A 2 on the downstream side in the rotation direction of the rotor 75 opens the opening 83 a of the air blowing unit 83. When the control means 100 determines that the position has passed, based on the detection signal from the detection sensor 88, the on-off valve 86 is opened. For this reason, the air from the air pump 84 flows into the air blowing portion 83, and the air is blown into the space S of the rotor 75.

  As shown in FIG. 11B, the position where the rotation of the rotor 75 advances and the area of the opening Sa of the space S that is open to the discharge port 53A of the rotary feeder is 1/3 or less of the total opening area. When the control means 100 determines that the blade 75A1 on the upstream side in the rotational direction of the rotor 75 has arrived based on the detection signal from the detection sensor 88, the on-off valve 86 is closed. For this reason, the blowing of the air to the space S of the rotor 75 stops.

  With such a configuration, the blade 75 </ b> A <b> 1 on the upstream side in the rotation direction of the rotor 75 that forms the space S by the rotation of the rotor 75 communicates with the joint pipe line 77 at the lower part of the rotary feeder 53. The air that is blown toward the space S from the air blowing portion 83 is close to the edge 53B on the downstream side in the rotational direction of the rotor 75 inside, and the opening area of the opening Sa of the space S to the discharge port 53A is reduced. When the flow in the direction of the discharge port 53A is inhibited, the blowing of air from the air blowing portion 83 to the space S is stopped. For this reason, when the air hits the blade 75A2 on the downstream side in the rotation direction of the rotor 75 that forms the space S by the rotation of the rotor 75, the air does not move back in the space S and remains in the rotary feeder 53. The developer T thus discharged can be reliably discharged to the discharge port 53A. Therefore, the discharge amount of the developer T from the rotary feeder 53 to the joint pipe line 77 is improved, and a decrease in the transport amount of the developer T can be prevented.

  The effective start and stop timings of air blowing from the air blowing unit 83 may vary depending on the amount of air to be blown, the capacity of the rotary feeder 53, etc., but the slit configuration of the encoder slit plate 87 is blown. The timing can be adjusted by adjusting according to the amount of air and the capacity of the rotary feeder 53.

  As shown in FIG. 12, the air blowing portion 83 is formed over the entire width in the axial direction of the blade 75 </ b> A of the rotor 75 of the rotary feeder 53, so that the space S of the rotor 75 where the developer T tends to remain. The air can also be blown to the end portion of the rotor 75 positioned in the axial direction. For this reason, the developer T remaining in the rotary feeder 53 can be reliably discharged to the discharge port 53A, and the amount of developer discharged from the rotary feeder 53 to the joint conduit 77 is improved. A decrease in the transport amount of the developer can be prevented.

  Further, as shown in FIG. 9, the air blowing portion 83 is formed so that the air from the air blowing portion 83 blows out toward the rotation center O of the rotor 75 of the rotary feeder 53. By blowing air toward the back (portion close to the center of the rotor 75), the remaining developer T in the back of the space S can also be pushed out by the air. For this reason, the developer T remaining in the rotary feeder 53 can be more reliably conveyed to the discharge port 53A, and the amount of developer discharged from the rotary feeder 53 to the joint pipe line 77 is improved. A decrease in the transport amount can be prevented.

  Also in the fifth and sixth embodiments, the developer T in the space S of the rotor 75 is pushed out from the rotary feeder 53 by the pressure of the air from the air blowing portion 83, so that the developer T is mechanically scraped. The stress on the developer T can be reduced compared to what is taken.

1Y, 1M, 1C, 1Bk Image carrier 5 (Y, M, C, Bk) Developing device 50 Developing section 51 Stirring section 53 Rotary feeder 53B Discharge port edge 75 Rotor 76 Stator 77 Developer transport section S Section (space)
78, 80, 82, 83 Air blowing part О Center of rotation

Japanese Patent No. 2008-299217 JP 2009-103751 A JP 2003-341840 A JP 2008-37508 A

Claims (8)

A developing unit that develops a latent image on the image carrier, a stirring unit that is provided outside the developing unit and contains a part of the developer and stirs the developer, and the developer in the stirring unit is quantitatively determined. In a developing device comprising: a rotary feeder that discharges; and a developer transport unit that transports the developer discharged from the rotary feeder to the developing unit using air pressure.
The rotary feeder includes a rotor and a stator that covers the rotor, and includes an air blowing unit that blows air toward a section formed by the rotor and the stator.   The developing device according to claim 1, wherein the air blowing unit blows air from the upstream side in the rotation direction of the discharge port edge of the rotary feeder toward the compartment.   The developer conveying unit is arranged so that air flowing in the developer conveying unit flows in parallel to the axial direction of the rotor, and the air blowing unit is closer to the air supply side than the developer conveying unit. The developing device according to claim 1, wherein a spraying pipe line is provided.   The developing device according to claim 1, wherein the air blowing unit blows air from the downstream side in the rotation direction of the discharge port edge of the rotary feeder toward the compartment.   The developing device according to claim 4, wherein a start timing and a stop timing of the air blowing from the air blowing portion toward the inside of the section are performed in accordance with the rotation of the rotor.   The developing device according to claim 4, wherein the air blowing portion is formed to extend over the entire width in the axial direction of the rotor.   The developing device according to claim 4, wherein the spray unit is formed so that air from the spray unit is blown out toward a rotation center of a rotor of the rotary feeder.   An image forming apparatus comprising the developing device according to claim 1.

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