JP6435837B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device and an image forming apparatus, and more particularly to a technique for discharging scattered toner in the developing device.

  In an image forming apparatus such as an electrophotographic printer, a copier, a facsimile machine, or a multifunction machine, an electrostatic latent image formed on the surface of a photosensitive drum is developed by a developing device to form a toner image. Then, the toner image is transferred and fixed on the sheet, and the image is printed on the sheet.

  The toner that has not been attracted to the electrostatic latent image in the developing step is scattered in the developing device. If such scattered toner leaks from the developing device and scatters to the outside, the inside of the image forming apparatus may be soiled, and further the print image quality may be deteriorated. Therefore, as described in Patent Document 1 below, scattered toner generated in the developing device is prevented from being sucked by the suction device and scattered outside.

JP 2004-294930 A

  In the existing image forming apparatus, a plurality of holes communicating with the duct are formed inside the casing of the developing device, and air is sucked from one end of the duct so that the scattered toner in the developing device is sucked and discharged from the plurality of holes. ing. In such a configuration, since the wind speed at the hole away from the suction port becomes weak, it is necessary to increase the entire suction force. However, if the overall suction force is excessively increased, even toner that is originally required for development may be sucked, and securing the volume of the waste toner bottle due to excessive suction of toner becomes a problem.

  SUMMARY An advantage of some aspects of the invention is that it is possible to efficiently discharge scattered toner without excessively increasing the discharge capability of the scattered toner in the developing device.

A developing device according to one aspect of the present invention includes a stirring member that stirs a developer including a non-magnetic toner and a magnetic carrier;
A developer carrier that is disposed opposite to an image carrier on which an electrostatic latent image is formed, and that supplies toner in the developer received from the stirring member to the image carrier;
A casing for housing the stirring member and the developer carrier;
A duct that is a hollow member that extends in the direction of the rotation axis of the developer carrier and has an opening at one end in the direction of the rotation axis of the developer carrier;
An exhaust mechanism covering the opening of the duct;
Inside the casing, a first through hole penetrating the duct is provided in the vicinity of an end portion close to the exhaust mechanism among both ends in the rotation axis direction of the developer carrier, and an end portion far from the exhaust mechanism A second through-hole penetrating the duct is provided in the vicinity;
Inside the duct, a first exhaust passage that leads from the first through hole to the opening and a second exhaust passage that leads from the second through hole to the opening are inner walls. Partitioned, the first exhaust flow path and the second exhaust flow path are independent,
The opening area of the first through hole is smaller than the opening area of the second through hole,
The cross-sectional area of the first exhaust flow path in the opening of the duct, rather smaller than the cross-sectional area of the second exhaust flow path in the opening of the duct,
The duct is disposed at an upper portion of the casing;
The first through hole and the second through hole are located above the developer carrier, and the developer carrier and the image carrier among the upper portions of the developer carrier. Are open toward the position on the developing nip side, which is the closest position .

  According to the present invention, the scattered toner can be efficiently discharged without excessively increasing the discharge capability of the scattered toner in the developing device. This makes it possible to save space of the waste toner bottle without sucking more toner than necessary.

1 is a front sectional view showing a structure of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic perspective view of a developing device according to an embodiment of the present invention. FIG. 3 is a right side view of the developing device of FIG. 2. It is I-I 'sectional drawing of FIG. FIG. 4 is a cross-sectional view taken along the line II-II ′ of FIG. 3. FIG. 4 is a sectional view taken along the line III-III ′ of FIG. 3. FIG. 4 is a sectional view taken along the line IV-IV ′ of FIG. 3. FIG. 3 is a right side view of the developing device of FIG. 2 and illustrates an example in which further through holes are formed. FIG. 9 is a cross-sectional view taken along the line I-I ′ of FIG. 8, illustrating an example in which further through holes are formed. 1 is a side sectional view showing a developing device of a two-component developing system, which is a developing device according to an embodiment of the present invention.

  Hereinafter, a developing device and an image forming apparatus including the developing device according to an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a front sectional view showing the structure of an image forming apparatus having a developing device according to an embodiment of the present invention.

  An image forming apparatus 1 according to an embodiment of the present invention is a multifunction machine having a plurality of functions such as a copy function, a printer function, a scanner function, and a facsimile function. The image forming apparatus 1 is configured to include an operation unit 47, an image forming unit 12, a fixing unit 13, a paper feeding unit 14, a document feeding unit 6, and an image reading unit 5 in the apparatus main body 11.

  The operation unit 47 receives instructions such as an image forming operation execution instruction and a document reading operation execution instruction from the operator regarding various operations and processes that can be executed by the image forming apparatus 1.

  When the image forming apparatus 1 performs a document reading operation, the image reading unit 5 optically reads a document fed by the document feeding unit 6 or a document placed on the document placing glass 161. Generate image data. The image data generated by the image reading unit 5 is stored in a built-in HDD or a computer connected to a network.

  When the image forming apparatus 1 performs an image forming operation, based on image data generated by a document reading operation, image data received from a computer connected to a network, image data stored in a built-in HDD, or the like, The image forming unit 12 forms a toner image on a recording paper P as a recording medium fed from the paper feeding unit 14. The image forming units 12M, 12C, 12Y, and 12Bk of the image forming unit 12 include a photosensitive drum 121, a developing device 2 that supplies toner to the photosensitive drum 121, a toner cartridge (not shown) that stores toner, A charging device 123, an exposure device 124, and a primary transfer roller 126 are provided.

  When performing color printing, the magenta image forming unit 12M, the cyan image forming unit 12C, the yellow image forming unit 12Y, and the black image forming unit 12Bk of the image forming unit 12 each receive image data. A toner image is formed on the photosensitive drum 121 through charging, exposure, and development processes based on the image composed of the respective color components, and the toner image is driven by the primary transfer roller 126 by the driving roller 125A and the driven roller 125B. The image is transferred onto the intermediate transfer belt 125 that is stretched around the belt.

  The intermediate transfer belt 125 is driven by a driving roller 125 </ b> A in a state where an image carrying surface on which a toner image is transferred is set on the outer peripheral surface thereof and in contact with the peripheral surface of the photosensitive drum 121. The intermediate transfer belt 125 travels endlessly between the driving roller 125A and the driven roller 125B while being synchronized with each photosensitive drum 121.

  The toner images of the respective colors transferred onto the intermediate transfer belt 125 are superimposed on the intermediate transfer belt 125 with the transfer timing adjusted to become a color toner image. The secondary transfer roller 210 conveys the color toner image formed on the surface of the intermediate transfer belt 125 from the sheet feeding unit 14 through the conveyance path 190 at the nip N between the intermediate transfer belt 125 and the driving roller 125A. The recording sheet P is transferred. Thereafter, the fixing unit 13 fixes the toner image on the recording paper P to the recording paper P by thermocompression bonding. The recording paper P on which the color image has been formed after completion of the fixing process is discharged to a discharge tray 151.

  A cleaning device (cleaning unit) 70 is provided on the intermediate transfer belt 125 portion stretched around the driven roller 125B. The cleaning device 70 collects toner remaining on the outer peripheral surface of the intermediate transfer belt 125.

  Next, a developing device according to an embodiment of the present invention will be described with reference to the drawings. The developing device is one of the components of the image forming unit 12 and is a device that performs the above-described developing process. FIG. 2 is a schematic perspective view of a developing device according to an embodiment of the present invention. The left side of the figure is the front of the image forming apparatus 1, and the right side of the figure is the back of the image forming apparatus 1.

  The developing device 2 includes magenta, cyan, yellow, and black casings 20M, 20C, 20Y, and 20Bk, and toner carriers 21M, 21C, 21Y, and 21Bk for each color, which are not shown in FIG. Each color magnetic roller, each color duct 22M, 22C, 22Y and 22Bk, an exhaust mechanism 23, and the like are provided.

  The toner carriers 21M, 21C, 21Y, and 21Bk are arranged to face the photosensitive drums 121 (FIG. 1) for the respective colors, and supply the respective color toners carried on the surface to the photosensitive drums 121, so that the respective colors. The electrostatic latent image is developed. The toner carriers 21M, 21C, 21Y, and 21Bk correspond to the toner carriers described in the claims.

  Magnetic rollers for each color (not shown) are arranged opposite to the toner carriers 21M, 21C, 21Y, and 21Bk, and supply the toners of the respective colors to the surfaces of the toner carriers 21M, 21C, 21Y, and 21Bk that are rotationally driven. . The magnetic roller corresponds to the developer carrier described in the claims. The magnetic roller will be described later with reference to the drawings.

  Casings 20M, 20C, 20Y, and 20Bk contain toner carriers 21M, 21C, 21Y, and 21Bk, magnetic rollers for each color, and other components, respectively.

  The ducts 22M, 22C, 22Y, and 22Bk are elongated hollow members that extend in the rotation axis direction of the toner carriers 21M, 21C, 21Y, and 21Bk, respectively, and are disposed on the upper portions of the casings 20M, 20C, 20Y, and 20Bk. Is done. As will be described later, through holes penetrating the ducts 22M, 22C, 22Y, and 22Bk are provided inside the casings 20M, 20C, 20Y, and 20Bk, respectively.

  The ducts 22M, 22C, 22Y, and 22Bk are closed at the rear end of the image forming apparatus 1 and open at the front end of the image forming apparatus 1. An exhaust mechanism 23 is provided so as to cover the entire openings of the ducts 22M, 22C, 22Y, and 22Bk.

  The exhaust mechanism 23 includes an electric fan 231. For example, the electric fan 231 generates an air flow that sucks air in the ducts 22M, 22C, 22Y, and 22Bk. Thereby, the air in the ducts 22M, 22C, 22Y, and 22Bk is sucked and discharged out of the developing device 2. Due to the air flow at this time, the toner scattered inside the casings 20M, 20C, 20Y, and 20Bk from the through holes is sucked into the exhaust mechanism 23 through the ducts 22M, 22C, 22Y, and 22Bk, and is not shown. It is collected in a waste toner bottle. That is, the ducts 22M, 22C, 22Y, and 22Bk serve as exhaust passages that discharge the toner scattered inside the casings 20M, 20C, 20Y, and 20Bk, respectively.

  In the exhaust mechanism 23, a filter 232 that prevents the passage of toner is provided at a position between the through hole and the electric fan 231 in the casings 20M, 20C, 20Y, and 20Bk. As a result, the toner sucked by the electric fan 231 can be prevented from entering the electric fan 231 and a failure of the electric fan 231 can be prevented.

  Next, a detailed configuration of the developing device 2 will be described. Since the configuration is the same for each color, the following description will be made without distinguishing the colors. FIG. 3 is a right side view of the developing device 2. In FIG. 3, the toner carrier is not shown to clearly show the inside of the casing 20.

  Inside the casing 20, a through hole 24 </ b> F penetrating the duct 22 is provided in the vicinity of the end close to the exhaust mechanism 23 of both ends in the rotation axis direction of the toner carrier (not shown), and in the vicinity of the end far from the exhaust mechanism 23. A through hole 24 </ b> R that penetrates the duct 22 is provided.

  4 is a cross-sectional view taken along the line I-I ′ of FIG. 3, that is, a top cross-sectional view of the duct 22. FIG. 5 is a cross-sectional view taken along the line II-II ′ of FIG. 3, that is, a front cross-sectional view including the through hole 24F. 6 is a cross-sectional view taken along the line III-III ′ of FIG. 3, that is, a front cross-sectional view including the through hole 24R. FIG. 7 is a cross-sectional view taken along the line IV-IV ′ of FIG. 3, that is, a front cross-sectional view near the opening of the duct 22. 5 to 7 show the toner carrier. The developing device 2 according to this embodiment will be described by taking an example of an interactive touch-down developing system in which a one-component developing method and a two-component developing method are combined.

  As shown in FIGS. 5 to 7, the developing device 2 includes a toner carrier 21, a developer carrier (an example of a magnetic roller) 25 that is disposed to face the toner carrier 21 and is driven to rotate, and a developer carrier. 25, a blade 26 disposed upstream in the rotational direction, and stirring members 27 and 28 for stirring the developer. The developer contains a non-magnetic toner and a magnetic carrier.

  Due to the magnetic force of the developer carrier 25, a developer having a carrier and toner adheres to the surface of the developer carrier 25. The blade 26 regulates the passing amount of the developer attached to the surface of the developer carrier 25 and forms a thin layer of developer on the surface of the developer carrier 25. The developer thin film formed on the surface of the developer carrier 25 moves according to the rotation of the developer carrier 25, and in the development nip where the developer carrier 25 and the toner carrier 21 are closest to each other. The toner contained in the developer moves to the surface of the toner carrier 21. The toner that has moved to the surface of the toner carrier 21 moves to the surface of a photoconductor drum (an example of an image carrier) that is arranged to face the toner carrier 21.

  Next, the detailed configuration of the duct 22 will be described. As shown in FIG. 4, inside the duct 22, an exhaust passage 22 </ b> F that communicates from the through hole 24 </ b> F to the opening 220 and an exhaust passage 22 </ b> R that communicates from the through hole 24 </ b> R to the opening 220 are partitioned by the inner wall 221. It has been. That is, the exhaust passage 22F and the exhaust passage 22R are independent in the duct 22.

  The opening 220 of the duct 22 is covered with the exhaust mechanism 23, and the exhaust mechanism 23 sucks the air in the duct 22 so that the scattered toner generated at the end of the toner carrier 21 near the exhaust mechanism 23 penetrates. The air is sucked from the hole 24F, and sucked into the exhaust mechanism 23 from the opening 220 through the exhaust passage 22F. On the other hand, the scattered toner generated at the end far from the exhaust mechanism 23 of the toner carrier 21 is sucked from the through hole 24R and sucked from the opening 220 to the exhaust mechanism 23 through the exhaust passage 22R.

  A large amount of scattered toner is generated at both ends of the toner carrier 21. For this reason, the scattered toner generated in the developing device 2 can be efficiently discharged to the outside by sucking the scattered toner from the through holes 24F and 24R as described above. In addition, since the exhaust flow path 22F and the exhaust flow path 22R are independent in the duct 22, a sufficient wind speed can be secured even in the through hole 24R far from the exhaust mechanism 23.

  In addition, since the former tends to increase the wind speed in the through hole 24F close to the exhaust mechanism 23 and the through hole 24R far from the exhaust mechanism 23, in order to make the wind speed uniform in the through holes 24F and 24R, for example, The cross-sectional area of the exhaust flow path 22F in the opening 220 of the duct 22 may be smaller than the cross-sectional area of the exhaust flow path 22R in the opening 220 of the duct 22. Alternatively, the opening area of the through hole 24F may be smaller than the opening area of the through hole 24R.

  As described above, according to the present embodiment, the scattered toner can be efficiently discharged without excessively increasing the discharged toner discharge capability in the developing device 2. This makes it possible to save space of the waste toner bottle without sucking more toner than necessary.

  The present invention is not limited to the configuration of the above embodiment, and various modifications can be made. For example, in the duct 22, one or more through holes are provided between the through hole 24 </ b> F as the first through hole in the rotation axis direction of the toner carrier 21 and the through hole 24 </ b> R as the second through hole. A hole may be further provided. FIG. 8 is a right side view of the developing device of FIG. 2, and illustrates the through hole 24P. FIG. 9 is a cross-sectional view taken along the line II ′ of FIG. 8, and the through hole 24P is partitioned from the through hole 24F and provided in the exhaust flow path 22R leading from the through hole 24R to the opening 220. An example is shown.

  The developing device 2 according to the above embodiment is an interactive touch-down developing system. However, the developing device according to the present invention is not limited to this, and may be a one-component developing method or a two-component developing method. .

  For example, as shown in FIG. 10, the present invention may be a two-component developing type developing device 2. FIG. 10 is a side sectional view showing the two-component developing type developing device 2. The developing device 2 includes a first spiral feeder 51, a second spiral feeder 52, and a developer carrier (developing roller) 53 in the casing 20.

  The first spiral feeder 51 agitates the toner replenished from the toner container (not shown) with the carrier and conveys the toner backward. The second spiral feeder 52 conveys the developer composed of toner and carrier delivered from the first spiral feeder 51 toward the front. The developer carrier 53 receives the developer conveyed by the second spiral feeder 52.

  When the developer is supplied to the peripheral surface of the developer carrier 53, the developer is restricted when passing the blade 230 with the rotation of the developer carrier 53, and the developer carrier 53. A thin layer of developer is formed on the peripheral surface. The developer thin layer moves according to the rotation of the developer carrier 53. At the developing nip N0 where the photosensitive drum 121 and the developer carrier 53 are closest to each other, the developer carrier 53 is applied by an AC electric field applied between the photosensitive drum 121 and the developer carrier 53. The toner contained in the developer above moves to the electrostatic latent image on the surface of the photosensitive drum 121, whereby the electrostatic latent image is developed, and a toner image is formed on the surface of the photosensitive drum.

The developing device 2 according to the two-component developing method is also provided with a duct 22 having the same structure as the developing device 2 shown in FIGS. The duct 22 is an elongated hollow member that extends in the direction of the rotation axis of the developer carrier 53, and is disposed in the upper part of the casing 20 above the developer carrier 53. In the duct 22, as in the developing device 2 shown in FIGS. 4 to 7, a through hole is formed in each end portion in the rotation axis direction of the toner carrier 21 in the duct 22. It is provided as a hole 24F. Furthermore, as shown in FIG. 9, the developing device 2 includes a second through hole from the through hole 24 </ b> F as the first through hole in the rotation axis direction of the toner carrier 21 inside the duct 22. One or a plurality of through holes may be further provided between the through holes 24R.
With this duct 22, even in the developing device 2 according to the two-component developing system, the scattered toner can be efficiently discharged without excessively increasing the discharge capability of the scattered toner in the developing device 2, and more toner than necessary is sucked. Therefore, it is possible to save the space of the waste toner bottle.

  In the above-described embodiment, the image forming apparatus according to an embodiment of the present invention has been described using a multifunction peripheral. However, this is merely an example, and other image forming apparatuses such as a printer, a copier, and a facsimile machine may be used. Good.

  Moreover, the structure shown by the said embodiment using FIG. 1 thru | or FIG. 10 is only one Embodiment of this invention, and is not the meaning which limits this invention to the said structure.

1 Image forming apparatus 121 Photosensitive drum (image carrier)
125 Intermediate transfer belt (transfer section)
210 Secondary transfer roller (transfer section)
13 Fixing portion P Recording paper 2 Developing device 20 Casing 21, 53 Toner carrier (developing roller)
22 Duct 220 Opening 221 Inner wall 22F Exhaust flow path (first exhaust flow path)
22R Exhaust flow path (second exhaust flow path)
23 Exhaust mechanism 231 Electric fan 232 Filter 24F Through hole (first through hole)
24R through hole (second through hole)
24P Through-hole 25 Magnetic roller (Developer carrier)

Claims (6)

An agitation member for agitating a developer containing a non-magnetic toner and a magnetic carrier;
A developer carrier that is disposed opposite to an image carrier on which an electrostatic latent image is formed, and that supplies toner in the developer received from the stirring member to the image carrier;
A casing for housing the stirring member and the developer carrier;
A duct that is a hollow member that extends in the direction of the rotation axis of the developer carrier and has an opening at one end in the direction of the rotation axis of the developer carrier;
An exhaust mechanism covering the opening of the duct;
Inside the casing, a first through hole penetrating the duct is provided in the vicinity of an end portion close to the exhaust mechanism among both ends in the rotation axis direction of the developer carrier, and an end portion far from the exhaust mechanism A second through-hole penetrating the duct is provided in the vicinity;
Inside the duct, a first exhaust passage that leads from the first through hole to the opening and a second exhaust passage that leads from the second through hole to the opening are inner walls. Partitioned, the first exhaust flow path and the second exhaust flow path are independent,
The opening area of the first through hole is smaller than the opening area of the second through hole,
The cross-sectional area of the first exhaust passage in the opening of the duct is smaller than the cross-sectional area of the second exhaust passage in the opening of the duct,
The duct is disposed at an upper portion of the casing;
The first through hole and the second through hole are located above the developer carrier, and the developer carrier and the image carrier among the upper portions of the developer carrier. Is a developing device that is open toward a position on the developing nip side where is closest to the developing nip.   The developing device according to claim 1, wherein the exhaust mechanism includes an electric fan.   The developing device according to claim 1, wherein the exhaust mechanism sucks air in the duct and releases the air out of the developing device.   The developing device according to claim 1, wherein the exhaust mechanism includes a filter that prevents passage of toner. The inside of the duct is further provided with one or more through holes between the first through hole and the second through hole in the rotation axis direction of the developer carrier. The developing device according to claim 4. An image carrier on which an electrostatic latent image is formed on the surface;
The developing device according to any one of claims 1 to 5, wherein the electrostatic latent image is developed to form a toner image;
A transfer portion for transferring the toner image onto a sheet;
An image forming apparatus comprising: a fixing unit that fixes the toner image transferred onto the sheet to the sheet by thermocompression bonding.