JP2014119469A - Image forming apparatus - Google Patents

Abstract

An image forming apparatus is continuously operated while avoiding a situation where a developing device cannot be driven.
A developing device, a replenishing means (including a developer replenishing port 95) for replenishing toner or a carrier as a component of the developer into the developing device, and a storage chamber (supply conveyance path) for accommodating the developer. 9, agitating and conveying path 10) and discharge ports 140 and 141 provided on the wall of the storage chamber so as to overflow the developer in the storage chamber. At least the discharge port 141 has a surplus agent receiving chamber for receiving the surplus developer, and a discharging means for discharging the surplus developer in the surplus agent receiving chamber to the outside, and the discharging means is in a state capable of being discharged at a predetermined timing. Become.
[Selection] Figure 8

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus having a developing device that keeps a developer inside.

  In Patent Document 1, in a developing device having a developer discharging mode for discharging a deteriorated developer in the developing device and supplying a new developer, the developer carrying member facing the photosensitive member is not rotated, so that the photosensitive member is rotated. A developing device that efficiently discharges a deteriorated developer without damaging the surface has been proposed. However, there is no description about the developer remaining in the developing device due to deterioration of fluidity, and there is a possibility that the development drive lock may occur when a new developer is charged.

  Patent Document 2 proposes a developing system that detects an increase in the bulk of the developer and controls the discharging means based on the detection result in a developing device that employs a premix developing system. However, particularly in a developing device corresponding to an extremely high printing speed, the bulk of the developer conveyed by the screw becomes unstable, and it is difficult to effectively control the discharging means.

  In this specification, “printing” is used in the same meaning as image formation using toner including printing. The image formation using toner includes not only printing on plain paper but also any image formation well known to those skilled in the art, such as primary transfer onto a transfer medium.

  In recent years, in order to cope with the high image quality of image forming apparatuses, the particle diameter of toner and carrier has been reduced. Developers composed of small-diameter particles have a very poor flowability of the developer as compared with conventional ones having a relatively large diameter. For this reason, the developer accumulates in a place where the stirring member does not reach in the developing device, or the developer stays in a place where the developer is difficult to flow, such as the back of the developer conveying surface of the stirring screw. Since the developer is solidified in the meantime and fills the screw pitch, problems such as a decrease in the developer conveying capability of the screw occur.

  As a conventional technique, an image forming apparatus that suppresses the above problems by maintaining a good developer in the developing device by adopting a premix system that replenishes the developer in the developing device and discharges the excess developer. It has been known. However, since the toner consumed by the image formation is replenished, the developer may not be replaced depending on the printing rate of the user. This is particularly noticeable when operating at low printing density for a long period of time. Further, since the deterioration of the developer fluidity greatly depends on the deterioration of the toner fluidity, the low fluidity density printing in which the toner in the developing device does not change promotes the deterioration of the developer fluidity. An immobile developer is generated in the apparatus, and the volume of the effective developing apparatus is reduced. Once such a state is reached, the volume of the developing device remains reduced because much of the immobile developer remains even if the developer fluidity is improved by the developer exchange or the like thereafter.

  2. Description of the Related Art Conventionally, in a dry two-component developing device, the image quality is maintained by periodically replacing the developer in the developing device because of the developer life due to developer deterioration. By adopting the above premix method, it is possible to achieve less developer life under standard usage conditions, but abnormal images due to developer deterioration may occur depending on user usage conditions (especially printing density). Therefore, even when the premix method is adopted, the developer needs to be replaced. The amount of developer to be replaced is determined by the internal volume of the developing device in the state where there is no stationary developer, so when the specified amount of developer is replenished to the developing device in which the volume is reduced by the stationary developer Since the developer can not be filled completely and the new developer has good fluidity, the developer is filled with the developer most closely, which increases the rotational load of the developer conveying screw, etc. In this case, the developing device cannot be driven.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to avoid a situation in which the developing device cannot be driven and to keep the image forming apparatus continuously operated.

  In order to achieve the above object, the present invention provides a developing device, a replenishing means for replenishing toner or carrier as a component of the developer into the developing device, a storage chamber for storing the developer, and development in the storage chamber. An overflow opening provided in the wall of the storage chamber so as to overflow the agent, and two or more overflow openings are provided, and the first overflow opening which is at least one of the overflow openings is the first A surplus developer receiving chamber for receiving surplus developer overflowing from one overflow opening, and a discharging means for discharging the surplus developer in the surplus agent receiving chamber to the outside, wherein the discharging means has a predetermined timing. It is characterized by being able to be discharged.

  According to the present invention, it is possible to avoid a situation in which the developing device cannot be driven, and to continue operating the image forming apparatus.

1 is a schematic configuration diagram of a copier 500 according to an embodiment of the present invention. It is a schematic block diagram of the process cartridge 18 which concerns on the said embodiment. FIG. 3 is a partial perspective view of the developing device 4 of FIG. 2. FIG. 3 is an external perspective view for explaining a toner replenishing position of the developing device 4 in FIG. 2. FIG. 5 is an external perspective view for explaining a configuration in the vicinity of a developer inlet 96 in FIG. 4. FIG. 7 is an external perspective view showing a replacement developer storage container 97 in the embodiment. FIG. 7 is an external perspective view for explaining a mode in which the supply port of the replacement developer storage container 97 of FIG. 6 and the developer supply port 96 of FIG. FIG. 3 is a schematic diagram illustrating a configuration in a longitudinal direction inside the developing device 4 of FIG. 2. In the Example of this invention, it is a figure which shows the ratio with respect to the total input amount of the amount of developer discharged | emitted at the time of developer injection.

  An embodiment in which the present invention is applied to an electrophotographic full-color image forming apparatus (hereinafter referred to as “copier 500”) will be described below.

<Embodiment 1>
FIG. 1 is a schematic configuration diagram of a copier 500 according to the first embodiment of the present invention. In FIG. 1, a copying machine 500 is fixed on a printer unit 100 as an image forming unit, a paper feeding device 200 as a recording medium supply unit that supplies transfer paper as a recording medium to the printer unit 100, and a printer unit 100. A scanner 300 as image reading means. An automatic document feeder 400 is fixed on the scanner 300.

  The printer unit 100 includes an image forming unit including four sets of process cartridges 18Y, 18M, 18C, and 18K for forming images of each color of yellow (Y), magenta (M), cyan (C), and black (K). 20 is provided. Y, M, C, and K added after the numerals of the respective symbols indicate members for yellow, magenta, cyan, and black (the same applies hereinafter). In addition to the process cartridges 18Y, 18M, 18C, and 18K, the printer unit 100 includes an optical writing unit 21 as a latent image writing unit, an intermediate transfer unit 17, a secondary transfer device 22, a registration roller pair 49, a belt fixing system. The fixing device 25 is provided.

  The optical writing unit 21 includes a light source (not shown), a polygon mirror, an f-θ lens, a reflection mirror, and the like, and irradiates a laser beam onto the surface of the photoreceptor 1 described later based on image data. The process cartridges 18Y, 18M, 18C, and 18K develop a latent image formed on the photosensitive member 1, a drum-shaped photosensitive member 1 as an image carrier, a charging device as a charging unit that charges the surface of the photosensitive member 1. The image forming apparatus includes a developing device 4 as a developing unit, a drum cleaning device as an image carrier cleaning unit that cleans the surface of the photoreceptor 1, and a static eliminator as a neutralizing unit that neutralizes the surface of the photoreceptor 1. Since the process cartridges 18Y, 18M, 18C, and 18K have the same configuration, the process cartridge 18Y for yellow will be described below.

  The surface of the photoreceptor 1Y is uniformly charged by the charging device. The surface of the photoreceptor 1Y that has been subjected to the charging process is irradiated with laser light that is modulated and deflected by the optical writing unit (exposure device) 21. Thereby, the potential of the surface of the photoreceptor 1Y of the irradiation part (exposure part) is attenuated. Due to the attenuation of the surface potential, an electrostatic latent image for Y is formed on the surface of the photoreceptor 1Y. The formed electrostatic latent image for Y is developed by the developing device 4Y to become a Y toner image. The Y toner image formed on the Y photoconductor 1Y is primarily transferred to an intermediate transfer belt 110 as an intermediate transfer member described later. The surface of the photoreceptor 1Y after the primary transfer is cleaned of the transfer residual toner by a drum cleaning device. Further, in the Y process cartridge 18Y, the photoreceptor 1Y cleaned by the drum cleaning device is discharged by the charge eliminator. Then, it is uniformly charged by the charging device and returns to the initial state. The series of processes as described above is the same for the other process cartridges 18M, 18C, and 18K.

  Next, the intermediate transfer unit 17 will be described. The intermediate transfer unit 17 includes an intermediate transfer belt 110 as an intermediate transfer member, a belt cleaning device 60 as an intermediate transfer member cleaning unit that cleans the surface of the intermediate transfer belt 110, and the like. The intermediate transfer unit 17 also includes a stretching roller 14, a drive roller 15, a secondary transfer backup roller 16, four primary transfer bias rollers 62Y, M, C, and K. The intermediate transfer belt 110 is tensioned by a plurality of rollers including the tension roller 14 so as to have a predetermined tension. The intermediate transfer belt 110 moves endlessly in the clockwise direction in the drawing by the rotation of the driving roller 15 driven by a belt driving motor (not shown).

  The primary transfer bias rollers 62Y, 62M, 62C, and 62K are disposed so as to be in contact with the inner peripheral surface side of the intermediate transfer belt 110, and receive a primary transfer bias from a power source (not shown). Further, the intermediate transfer belt 110 is pressed toward the photoreceptors 1Y, 1M, 1C, and 1K from the inner peripheral surface side to form primary transfer nips. In each primary transfer nip, a primary transfer electric field is formed between the photoreceptor 1 and the primary transfer bias roller 62 due to the influence of the primary transfer bias. The Y toner image formed on the Y photoconductor 1Y is primarily transferred onto the intermediate transfer belt 110 by the influence of the primary transfer electric field and nip pressure. On the Y toner image, the M, C, K toner images formed on the M, C, K photoconductors 1M, C, K are sequentially superposed and primarily transferred. By this primary transfer of superposition, a four-color superposed toner image (hereinafter referred to as “four-color toner image”) as a multiple toner image is formed on the intermediate transfer belt 110.

  The four-color toner image superimposed and transferred onto the intermediate transfer belt 110 is secondarily transferred onto a transfer sheet (not shown) as a recording medium at a secondary transfer nip described later. Transfer residual toner remaining on the surface of the intermediate transfer belt 110 after passing through the secondary transfer nip is cleaned by a belt cleaning device 60 that sandwiches the belt with the driving roller 15 on the left side in the drawing.

  Next, the secondary transfer device 22 will be described. Below the intermediate transfer unit 17 in the figure, a secondary transfer device 22 is disposed in which a paper conveying belt 24 is stretched by two stretching rollers 23. The paper transport belt 24 moves endlessly in the counterclockwise direction in the drawing in accordance with the rotational drive of at least one of the stretching rollers 23. Of the two stretching rollers 23, one stretching roller 23 disposed on the right side in the drawing, that is, the upstream stretching roller 23 disposed on the upstream side in the transfer sheet conveying direction is the intermediate transfer unit 17. The intermediate transfer belt 110 and the paper transport belt 24 are sandwiched between the secondary transfer backup roller 16. By this sandwiching, a secondary transfer nip is formed in which the intermediate transfer belt 110 of the intermediate transfer unit 17 and the paper transport belt 24 of the secondary transfer device 22 are in contact with each other. A secondary transfer bias having a polarity opposite to that of the toner is applied to the one (upstream side) stretching roller 23 by a power source (not shown). By applying the secondary transfer bias, the four-color toner image on the intermediate transfer belt 110 of the intermediate transfer unit 17 is applied from the belt side to the one (upstream) stretching roller 23 side in the secondary transfer nip. A secondary transfer electric field to be electrostatically moved is formed. The transfer paper fed into the secondary transfer nip so as to synchronize with the four-color toner image on the intermediate transfer belt 110 by a registration roller pair 49 described later has four colors affected by the secondary transfer electric field and nip pressure. The toner image is secondarily transferred. Instead of the secondary transfer method in which the secondary transfer bias is applied to the one (upstream side) stretching roller 23, a charger for charging the transfer paper in a non-contact manner may be provided.

  In the paper feeding device 200 provided at the lower part of the copying machine 500 main body, a plurality of paper feeding cassettes 44 in which a plurality of transfer sheets can be stacked and stored in a bundle of sheets are arranged so as to overlap each other in the vertical direction. It is installed. Each paper feed cassette 44 presses the paper feed roller 42 against the uppermost transfer paper in the paper bundle. Then, by rotating the paper feed roller 42, the uppermost transfer paper is sent out toward the paper feed path 48.

  The paper feed paths 46 and 48 that receive the transfer paper delivered from the paper feed cassette 44 have a plurality of conveying roller pairs 47 and a registration roller pair 49 provided near the end in the paper feed path 48. . Then, the transfer paper is conveyed toward the registration roller pair 49. The transfer sheet conveyed toward the registration roller pair 49 is sandwiched between the rollers of the registration roller pair 49. On the other hand, in the intermediate transfer unit 17, the four-color toner image formed on the intermediate transfer belt 110 enters the secondary transfer nip as the belt moves endlessly. The registration roller pair 49 sends out the transfer paper sandwiched between the rollers at a timing at which the transfer paper can be brought into close contact with the four-color toner image at the secondary transfer nip. Thereby, in the secondary transfer nip, the four-color toner image on the intermediate transfer belt 110 is in close contact with the transfer paper. Then, it is secondarily transferred onto the transfer paper and becomes a full color image on the white transfer paper. The transfer paper on which the full-color image is formed in this manner exits the secondary transfer nip as the paper transport belt 24 moves endlessly, and then is sent from the paper transport belt 24 to the fixing device 25.

  The fixing device 25 includes a belt unit that stretches the fixing belt 26 by two rollers and moves endlessly, and a pressure roller 27 that is pressed toward one roller of the belt unit. The fixing belt 26 and the pressure roller 27 are in contact with each other to form a fixing nip, and the transfer paper received from the paper transport belt 24 is sandwiched therebetween. Of the two rollers in the belt unit, the roller that is pressed from the pressure roller 27 has a heat source (not shown) inside, and heats the fixing belt 26 by the heat generated by the heat source. The heated fixing belt 26 heats the transfer paper sandwiched in the fixing nip. The full color image is fixed on the transfer paper by the influence of the heating and the nip pressure.

  The transfer paper subjected to the fixing process in the fixing device 25 is stacked on the stack portion 57 provided outside the left side plate in the drawing of the printer housing, or forms a toner image on the other surface. Any one of the transport modes to be returned to the secondary transfer nip is selected.

  When a document (not shown) is copied, for example, a bundle of sheet documents is set on the document table 30 of the automatic document feeder 400. However, when the original is a single-sided original that is closed in a main form, it is set on the contact glass 32. Prior to this setting, the automatic document feeder 400 is opened with respect to the copying machine main body, and the contact glass 32 of the scanner 300 is exposed. Thereafter, the single-bound original is pressed by the closed automatic document feeder 400. When a copy start switch (not shown) is pressed after the document is set in this way, the document reading operation by the scanner 300 starts. On the other hand, when a sheet document is set on the automatic document feeder 400, the automatic document feeder 400 automatically moves the sheet document to the contact glass 32 prior to the document reading operation. In the document reading operation, first, the first traveling body 33 and the second traveling body 34 start traveling together, and light is emitted from a light source provided in the first traveling body 33. Then, the reflected light from the document surface is reflected by a mirror provided in the second traveling body 34, passes through the imaging lens 35, and then enters the reading sensor 36. The reading sensor 36 constructs image information based on the incident light.

  In parallel with such document reading operation, each device in each of the process cartridges 18Y, 18M, 18C, 18K, the intermediate transfer unit 17, the secondary transfer device 22, and the fixing device 25 starts driving. Then, based on the image information constructed by the reading sensor 36, the optical writing unit (exposure device) 21 is driven and controlled, and Y, M, C, and K toner images on the respective photoreceptors 1Y, 1M, 1C, and 1K. Is formed. These toner images become four-color toner images superimposed and transferred on the intermediate transfer belt 110.

  Further, almost simultaneously with the start of the document reading operation, the paper feeding operation is started in the paper feeding device 200. In this paper feeding operation, one of the paper feeding rollers 42 is selectively rotated, and the transfer paper is sent out from one of the paper feeding cassettes 44 accommodated in the paper bank 43 in multiple stages. The fed transfer paper is separated one by one by the separation roller 45 and enters the paper feed path 46, and is then transported toward the secondary transfer nip by the transport roller pair 47. In some cases, paper feeding from the manual feed tray 51 is performed instead of such paper feeding from the paper feeding cassette 44. In this case, after the manual feed roller 50 is selectively rotated to feed the transfer paper on the manual feed tray 51, the separation roller 52 separates the transfer paper one by one and feeds it to the manual feed path 53 of the printer unit 100. Make paper.

  In the case of forming a multicolor image composed of two or more colors of toner, the copying machine 500 stretches the intermediate transfer belt 110 so that the upper stretched surface is almost horizontal, and all the upper stretched surface is placed on the upper stretched surface. Photoconductors 1Y, 1M, 1C, and 1K are brought into contact with each other. On the other hand, when forming a monochrome image consisting of only K toner, the intermediate transfer belt 110 is tilted to the lower left in the drawing by a mechanism (not shown) and the upper stretched surface is set to Y, M, C. The photoconductors 1Y, 1M, and 1C are separated. Of the four photoconductors 1Y, 1M, 1C, and 1K, only the K photoconductor 1K is rotated counterclockwise in the drawing to form only the K toner image. At this time, for Y, M, and C, not only the photosensitive member 1 but also the developing device 4 is stopped, and each member of the photosensitive member 1 and the developing device 4 and the toner and magnetic carrier (hereinafter referred to as the developing device 4). Unnecessary consumption of a two-component developer (hereinafter referred to as “developer”).

  The copier 500 includes a control unit as a control unit (not shown) configured by a CPU that controls each device in the copier 500, an operation display unit (not illustrated) configured by a liquid crystal display, various key buttons, and the like. It has. The operator sends a command to the control unit by a key input operation on the operation display unit, so that the single-sided printing mode, which is a mode for forming an image only on one side of the transfer paper, can be selected from, for example, three modes. One can be selected. The three single-sided printing modes include a direct discharge mode, a reverse discharge mode, and a reverse decal discharge mode.

  FIG. 2 shows the process cartridge 18 installed in the copying machine 500. FIG. 2 is an enlarged configuration diagram showing the developing device 4 and the photoreceptor 1 provided in the process cartridges 18Y, 18M, 18C, and 18K, respectively, in the copying machine according to the present embodiment. Since the four process cartridges 18Y, 18M, 18C, and 18K have substantially the same configuration except that the colors of the toners to be handled are different from each other, Y, M, C, and the like denoted by “4” in FIG. The subscript K is omitted.

  As shown in FIG. 2, the process cartridge 18 includes a photosensitive drum 1 as an image carrier, a charging unit (not shown), a developing device 4 (developing unit), and a photosensitive member cleaning unit (not shown). In addition, a premix development method (development method in which carrier is replenished / discharged as appropriate) is employed. The photosensitive drum 1 as an image carrier is a negatively charged organic photosensitive member, and is rotationally driven counterclockwise by a rotation driving mechanism (not shown).

  Here, the developing device 4 in the present embodiment is of a premix developing system, and a new carrier C (developer G) is appropriately supplied from the agent cartridge into the developing device 4 and deteriorated. The developer G is discharged toward a not-shown agent storage container installed outside the developing device 4. The developer cartridge contains developer G (toner T and carrier C) to be supplied into the developing device 4 therein. The agent cartridge functions as a toner cartridge that supplies new toner T to the developing device 4, and also functions as a supply unit that supplies new carrier C to the developing device 4. In this embodiment, the mixing ratio (toner concentration) of the toner T with respect to the carrier C in the developer G of the agent cartridge is set to be relatively high.

  As shown in FIG. 2, the surface of the photosensitive member 1 is charged by a charging device (not shown) while rotating in the direction of arrow G in the drawing. An electrostatic latent image is formed on the surface of the charged photoreceptor 1 by laser light emitted from an optical writing unit (exposure device) (not shown), and toner is supplied to the electrostatic latent image from the developing device 4. A toner image is formed.

  The developing device 4 stores a developer containing toner and a carrier, and supplies the toner to the latent image on the surface of the photosensitive member 1 while developing the developer in the direction of arrow I in the drawing as a developer carrying member. The developing roller 5 is provided. The developing roller 5 includes a developing sleeve 81 as a developer support means that can rotate, and includes a magnet roller 82 as a first magnetic field generating means that is composed of a plurality of magnetic poles and that can rotate in the direction of arrow A in the figure. .

  Further, a carrier recovery roller 13 as a carrier recovery means is provided below the developing roller 5 and at a position close to the developing roller 5 and the photosensitive member 1 on the downstream side in the surface movement direction of the photosensitive member 1. . Similarly to the developing roller 5, the carrier recovery roller 13 also includes a carrier recovery sleeve 90 as a rotatable carrier support means, and a carrier as second magnetic field generation means (carrier recovery magnetic field generation means) composed of a plurality of fixed magnetic poles. A collection magnet roller 91 is included. The carrier adhering to the photoreceptor 1 is collected by the carrier collection roller 13 and returned to the developing device 4 by the magnetic force of the carrier collection magnet roller 91 and the rotation of the carrier collection sleeve 90.

  Further, the developing device 4 supplies the developer to the developing roller 5 along the axial direction of the developing roller 5 with respect to the back side of the paper surface shown in FIG. It has a supply screw 8 as a supply conveyance member that conveys the developer toward the rear side. A doctor blade 12 serving as a developer regulating means for regulating the developer supplied to the developing roller 5 to a thickness suitable for development is provided downstream of the developing roller 5 facing the supply screw 8 in the developer transport direction. I have. Further, on the downstream side in the developer transport direction with respect to the developing region that is the portion of the developing roller 5 facing the photoreceptor 1, the developer that collects the developed developer that has passed through the developing region and separated from the surface of the developing roller 5 is collected. The conveyance path 7 faces the developing roller 5. The collection conveyance path 7 is a collection conveyance member that conveys the collected developer collected in the same direction as the supply screw 8 along the axial direction of the developing roller 5. I have. A supply conveyance path 9 provided with a supply screw 8 is arranged in parallel above the developing roller 5, and a collection conveyance path 7 provided with a collection screw 6 is arranged in parallel below the development roller 5.

  Further, the developing device 4 is provided with an agitation transport path 10 in parallel with the supply transport path 9 and the recovery transport path 7. The stirring conveyance path 10 is inclined so as to be substantially the same height as the supply conveyance path 9 on the rear side and on the front side of the collection conveyance path 7. Further, the agitating / conveying path 10 is in the direction opposite to the supply screw 8 while stirring the developer along the axial direction of the developing roller 5, that is, on the front side of the paper shown in FIG. As a stirring / conveying member that conveys in the direction of (in some cases), a helical stirring screw 11 is provided that is inclined in the axial direction. The supply conveyance path 9 and the stirring conveyance path 10 are partitioned by a first partition wall 133 as a partition wall. The supply conveyance path 9 and the agitation conveyance path 10 of the first partition wall 133 have an opening on the front side in the figure, and the supply conveyance path 9 and the agitation conveyance path 10 communicate with each other. Further, the supply conveyance path 9 and the collection conveyance path 7 are partitioned by a second partition wall 134. The supply conveyance path 9 and the collection conveyance path 7 of the second partition wall 134 have an opening on the back side in the drawing, and the supply conveyance path 9 and the collection conveyance path 7 communicate with each other. In addition, the two developer conveyance paths of the agitation conveyance path 10 and the recovery conveyance path 7 are partitioned by a third partition wall 135 as a partition member. The third partition wall 135 has an opening on the back side in the figure, and the stirring conveyance path 10 and the collection conveyance path 7 communicate with each other.

  The supply screw 8, the recovery screw 6 and the stirring screw 11, which are developer conveying members, are made of resin or metal screws. The diameters of the screws are 26 (mm) for the supply screw 8 and the recovery screw 6, and the stirring screw 11 is φ30 (mm). The supply screw 8 is a double winding with a screw pitch of 54 (mm), the recovery screw 6 is a double winding with a screw pitch of 36 (mm), and the stirring screw 11 has a screw pitch of 54 (mm). It is a double roll. The number of rotations of each screw is set to about 600 (rpm).

  The developer carried on the developing roller 5 is thinned by a doctor blade 12 made of stainless steel, and then transported to a developing region that is a portion facing the photosensitive member 1, so that the latent image on the photosensitive member 1 is developed. Done. The diameter of the developing roller 5 is φ40 (mm), and the gap between the doctor blade 12 and the photoreceptor 1 is about 0.3 (mm).

  The developer after development is collected in the collection conveyance path 7, conveyed to the back side in FIG. 2, and developed to the agitation conveyance path 10 at the opening of the third partition wall 135 provided in the non-image area portion. The agent is transferred. In addition, in the vicinity of the opening of the second partition wall 134 on the downstream side in the developer conveyance direction in the supply conveyance path 9, on the upper side of the supply conveyance path 9, as shown in FIG. Toner 9 is supplied.

Next, the circulation of the developer in the three developer transport paths will be described with reference to FIG. FIG. 3 is a partial perspective view of the developing device 4 for explaining the flow of the developer in the developer transport path. Each arrow in the figure indicates the moving direction of the developer. In FIG. 3, the developer is supplied in contact with the developing roller 5 while moving in the supply conveyance path 9 that receives the supply of the developer from the agitation conveyance path 10. The surplus developer that has moved to the downstream end in the transport direction of the supply transport path 9 without being supplied to the developing roller 5 is supplied to the recovery transport path 7 from the surplus opening of the second partition wall 134 (arrow in FIG. 3). E).
On the other hand, the developer supplied to the developing roller 5 is used for development in the developing region, and then separated from the developing roller 5 and separated from the developing roller 5 and is delivered to the collection conveyance path 7. The collected developer that has been transferred from the developing roller 5 to the collection conveyance path 7 and conveyed to the downstream end in the conveyance direction of the collection conveyance path 7 by the collection screw 6 passes through the collection opening of the third partition wall 135 to the stirring conveyance path 10. Supplied (arrow F in FIG. 3).

  In the agitating / conveying path 10, the excess developer supplied from the supply / conveying path 9, the collected developer collected in the collecting / conveying path 7, and the toner replenished from a toner replenishing port 95 (see FIG. 4) described later (FIG. 3 arrow t) is stirred. The agitated developer is conveyed downstream in the conveying direction of the agitating screw 11 and upstream in the conveying direction of the supply screw 8, and is supplied to the supply conveying path 9 from the supply opening of the first partition wall 133. (Arrow D in FIG. 3).

  A toner concentration sensor (not shown) composed of a magnetic permeability sensor is provided below the agitation transport path 10, and a toner supply control device (not shown) is operated based on the output of the toner concentration sensor. Toner is supplied from the developer cartridge.

  In the developing device 4 shown in FIG. 3, a supply conveyance path 9 and a collection conveyance path 7 are provided, and developer supply and collection are performed in different developer conveyance paths, so that developed developer is supplied to the supply conveyance path 9. There is no contamination. For this reason, it is possible to suppress a decrease in the toner concentration of the developer supplied to the developing roller 5 toward the downstream side of the supply conveyance path 9 in the conveyance direction. Further, since the recovery conveyance path 7 and the agitation conveyance path 10 are provided and the developer recovery and agitation are performed in different developer conveyance paths, the developed developer does not fall during the agitation. Thereby, since the sufficiently stirred developer is supplied to the supply conveyance path 9, it is possible to suppress the developer supplied to the supply conveyance path 9 from being insufficiently stirred. In this way, the toner density of the developer in the supply conveyance path 9 can be suppressed from decreasing, and the developer in the supply conveyance path 9 can be prevented from being insufficiently stirred, so the image density during development can be reduced. Can be constant.

  In addition, as a developer used in this embodiment, a developer having the following configuration can be used.

  The toner used in this embodiment contains at least a binder resin and a colorant, and if necessary, a release agent, a charge control agent, and other components. In addition to the above-mentioned additives, a fluidity improver and other components are added as necessary. For these materials, all known materials are possible.

  Examples of the binder resin include styrene, parachlorostyrene, vinyl toluene, vinyl chloride, vinyl acetate, vinyl propionate, methyl (meth) acrylate, ethyl (meth) tacrylate, propyl (meth) acrylate, (meth ) N-butyl acrylate, isobutyl (meth) acrylate, dodecyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) Hydroxypropyl acrylate, 2-chloroethyl (meth) acrylate, (meth) acrylonitrile acid, (meth) acrylamide, (meth) acrylic acid, vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether. Examples include a weight body of monomers such as vinyl methyl ketone, N-vinyl pyrrolidone, N-vinyl pyridine and butadiene, a copolymer composed of two or more of these monomers, or a mixture thereof. In addition, polyester resin, polyol resin, polyurethane resin, polyamide resin, epoxy resin, rosin, modified rosin, terbene resin, phenol resin, hydrogenated petroleum resin, ionomer resin, silicone resin, ketone resin, xylene resin, etc. alone or in combination Can be used.

  As the colorant, all known dyes and pigments can be used. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher, Yellow lead, Titanium yellow, Polyazo yellow, Oil yellow, Hansa yellow (GR, A, RN, R), Pigment yellow L, Benzidine yellow (G, GR), Permanent yellow (NCG), Vulcan fast yellow (5G, R) ), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Red Dan, Lead Zhu, Cadmium Red, Cadmium Mercury Red, Antimon Zhu, Permanent Red 4R, Para Red, Phi Se Red, Parachlor Ortonito Aniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmin Min BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Resol Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Tolujing Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake , Thioindigo red B, thioindigo maroon, oil red, quinacridone red, pyrazolone red, Riazo Red, Chrome Vermillion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), indigo, ultramarine blue, bitumen, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake, Malachite Green Lake, Phthalo Cyanine green, anthraquinone green, titanium oxide, zinc white, litbon and mixtures thereof can be used. The amount used is generally 0.1 to 50 parts by weight per 100 parts by weight of the binder resin.

  Examples of the charge control agent include nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdate chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts). .), Alkylamide, phosphorus simple substance or compound, tungsten simple substance or compound, fluorine-based activator, salicylic acid metal salt, metal salt of salicylic acid derivative, and the like. The amount of charge control agent used is determined by the type of binder resin, the presence or absence of additives used as necessary, and the toner production method including the dispersion method, and is not uniquely limited. Preferably, it is used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the binder resin. The range of 2 to 5 parts by weight is preferable. If the amount is less than 0.1 parts by weight, the toner is not practically negatively charged. When the amount exceeds 10 parts by weight, the chargeability of the toner is too high, and the electrostatic attraction force with the carrier increases, leading to a decrease in developer fluidity and a decrease in image density.

  Examples of the release agent include low molecular weight polyolefin wax such as low molecular weight polyethylene and low molecular weight polypropylene, synthetic hydrocarbon wax such as Fischer-Tropsch wax, beeswax, carnauba wax, candelilla wax, rimming wax, and montan wax. Natural waxes such as paraffin wax, petroleum wax such as microcrystalline wax, higher fatty acids such as stearic acid, palmitic acid, myristic acid, metal salts of higher fatty acids, higher fatty acid amides, and various modified waxes thereof. Can be mentioned. These may be used alone or in combination of two or more, but it is preferable to use those having a melting point in the range of 70 to 125 (° C). By setting the melting point to 70 (° C) or higher, it is possible to obtain a toner having excellent transferability and durability. By setting the melting point to 125 ° C or lower, the toner melts quickly at the time of fixing and exhibits a reliable release effect. it can. The amount of these release agents used is preferably 1 to 15 (% by mass) based on the toner. If it is less than 1 (mass%), the effect of preventing offset is insufficient, and if it is 15 (mass%) or more, the transferability and durability are lowered.

As an additive (external additive), fine particles having a volume average particle size of 50 to 500 (nm) and a bulk density of 0.3 (g / cm ³ ) or more are added. The amount of external addition is preferably 0.2 to 3 (% by mass) with respect to the toner base. If the amount is less than this range, the effect of forming an appropriate gap between the toners or between the toner and the others is not exhibited. On the other hand, when the amount is large, the fluidity is inhibited or the amount of desorption increases, so that an aggregate of external additives is formed, and the image quality is deteriorated. In addition to the above-mentioned additives, additives outside this range can be added, and it is preferable to add fine particles having a small volume average particle diameter for the purpose of improving fluidity.

In the additive in the present embodiment, the inorganic compounds include SiO ₂ , TiO ₂ , Al ₂ O ₃ , MgO, CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , BaO, CaO, K ₂ O, Examples include Na ₂ O, ZrO ₂ , CaO · SiO ₂ , K ₂ O (TiO ₂ ) n, Al ₂ O ₃ · 2SO ₂ , CaCO ₃ , MgCO ₃ , BaSO ₄ , MgSO ₄ , SrTiO _{3 and the} like. Of these, SiO ₂ , TiO ₂ , and Al ₂ O ₃ are preferable. In particular, these inorganic compounds may be hydrophobized with various coupling agents, hexamethyldisilazane, dimethyldichlorosilane, octyltrimethoxysilane, and the like. Further, the organic compound additive may be a thermoplastic resin or a thermosetting resin, for example, vinyl resin, polyurethane resin, epoxy resin, polyester resin, polyamide resin, polyimide resin, silicon resin, phenol resin, melamine resin. , Urea resin, aniline resin, ionomer resin, polycarbonate resin and the like. As the resin fine particles, two or more of the above resins may be used in combination. Of these, vinyl resins, polyurethane resins, epoxy resins, polyester resins, and combinations thereof are preferred because an aqueous dispersion of fine spherical resin particles is easily obtained. Specific examples of vinyl resins include polymers obtained by homopolymerization or copolymerization of vinyl monomers, such as styrene- (meth) acrylic acid ester copolymers, styrene-butadiene copolymers, (meth) acrylic acid. -Acrylic ester copolymer, styrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer, styrene- (meth) acrylic acid copolymer, and the like.

  The additive (fine particles) in this embodiment is excellent as a toner for a developer in the developing device. That is, the contact area with the toner particles, the photoconductor drum, and the charge imparting member is very small and contacts evenly, so the effect of reducing adhesion is great and effective in improving development / transfer efficiency. Furthermore, since it acts as a roller, it is buried in the toner particles even when cleaning the cleaning drum and the photosensitive drum under high stress (high load, high speed, etc.) without wearing or damaging the photosensitive drum. It is difficult to remove or return even after being buried a little, so that stable characteristics can be obtained over a long period of time. Further, the toner is moderately detached from the surface of the toner and accumulated at the tip of the cleaning blade, and the so-called dam effect has an effect of preventing a phenomenon that the toner passes from the blade.

  As a method for producing the toner in the present embodiment, a method obtained by melting and kneading a toner constituent material and then pulverizing and classifying is generally used as a conventional method, but is not limited to this method. A method is possible. As the polymerization method, a suspension polymerization method, an emulsion polymerization method, a dispersion polymerization method, and the like are possible. Although different from the polymerization method, in addition to a dissolution suspension method, a polymer suspension method, etc., an extension reaction method or the like can be used. . Other than the conventional method is preferable in that the toner having the above-described particle size range and circularity can be easily obtained. Further, the circularity may be adjusted by subjecting the toner after pulverization and classification to heat treatment.

  The method for adding the additive in the present embodiment is not particularly limited, and a method in which the toner base particles and the additive are mechanically mixed and adhered using various known mixing devices, or a toner base in a liquid phase. There is a method in which particles and additives are uniformly dispersed with a surfactant or the like, and after an adhesion treatment, dried.

  The particle size distribution of the toner described above can be measured by using a toner particle size distribution measuring apparatus by the Coulter counter method. Examples of these devices include Coulter Counter TA-II and Coulter Multisizer II (both manufactured by Coulter). The measurement method is described below.

  First, 0.1 to 5 (ml) of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 (ml) of the aqueous electrolytic solution. Here, the electrolytic solution is prepared by preparing about 1 (%) NaCl aqueous solution using primary sodium chloride, and for example, ISOTON-II (manufactured by Coulter) can be used. Here, 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the weight and number of toner particles or toner are determined by using the 100 (μm) aperture as the aperture by the above-described measuring apparatus. Measure and calculate weight distribution and number distribution. From the obtained distribution, the weight average particle diameter and the number average particle diameter of the toner can be obtained. As a channel, it is less than 2.00-2.52 (micrometer); 2.52-3.17 (micrometer); 3.17-4.00 (micrometer); 4.00-5.04 (micrometer) Less than 5.04 to 6.35 (μm); 6.35 to less than 8.00 (μm); 8.00 to less than 10.08 (μm); 10.08 to less than 12.70 (μm); 12.70 to less than 16.00 (μm); 16.00 to less than 20.20 (μm); 20.20 to less than 25.40 (μm); 25.40 to less than 32.00 (μm); Using 13 channels of 00 to less than 40.30 (μm), particles having a particle size of 2.00 (μm) or more and less than 40.30 (μm) are targeted.

The circularity of the toner described above is a value obtained by the following equation (1).
Circularity = (perimeter of a circle having the same area as the projected area of the particle) / (perimeter of the projected image of the particle) (1)
The circularity is an index of the degree of unevenness of the toner particles, and indicates 1.00 when the toner is a perfect sphere. The more complicated the surface shape, the smaller the circularity. The circularity can be measured using, for example, a flow particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics. As a specific measuring method, a surfactant, preferably an alkylbenzene sulfonate, is added in an amount of 0.1 to 0.5 (as a dispersant) in 100 to 150 (ml) of water from which impure solids have been previously removed. ml) and about 0.1 to 0.5 (g) of a measurement sample. The suspension in which the sample is dispersed is subjected to dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the concentration of the dispersion is set to 3000 to 10,000 (pieces / μl), and the shape of the toner is measured with the above-described apparatus.

  Hereinafter, the carrier used in this embodiment will be described supplementarily. The carrier used in the present embodiment is formed so that the weight average particle diameter is 20 to 60 (μm) (preferably 20 to 45 (μm)). This particle size range is also excellent as a carrier for the developer in the developing device. When the average particle diameter of the carrier is less than 20 (μm), the fine particles are increased in the distribution of the carrier particles, and the magnetization per particle may be lowered to cause carrier scattering. On the other hand, if the average particle diameter of the carrier exceeds 45 (μm), the carrier spikes during the development process become rough, and the uniformity of solid and halftone may be inferior (particularly, the average particle diameter is It becomes remarkable when it exceeds 60 (μm)). In addition, since the specific surface area is reduced, toner scattering may occur in a small particle size toner.

  The carrier is not particularly limited except for the particle diameter, and can be appropriately selected according to the purpose. However, a carrier having a core material and a resin layer covering the core material is preferable. There is no restriction | limiting in particular as a material of a core material, It can select suitably from well-known things, For example, 50-90 (emu / g) manganese-strontium (Mn-Sr) type material, manganese-magnesium ( Mn—Mg) -based materials and the like are preferable, and highly magnetized materials such as iron powder (100 (emu / g) or more) and magnetite (75 to 120 (emu / g)) are preferable in terms of securing image density. Also, copper-zinc (Cu-Zn) type (30 to 80 (emu / g)) or the like is advantageous in that it can weaken the contact with the photosensitive drum in which the toner is in a spiked state and is advantageous for high image quality. The weakly magnetized material is preferred. These may be used alone or in combination of two or more.

  The material for the resin layer of the carrier is not particularly limited and can be appropriately selected from known resins according to the purpose. Examples thereof include amino resins, polyvinyl resins, polystyrene resins, and halogenated olefin resins. Polyester resin, polycarbonate resin, polyethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, polytrifluoroethylene resin, polyhexafluoropropylene resin, copolymer of vinylidene fluoride and acrylic monomer, fluoride Examples thereof include a copolymer of vinylidene and vinyl fluoride, a fluoroterpolymer such as a terpolymer of tetrafluoroethylene, vinylidene fluoride, and a non-fluorinated monomer, and a silicone resin. These may be used individually by 1 type and may use 2 or more types together.

  The resin layer may contain conductive powder or the like as necessary. Examples of the conductive powder include metal powder, carbon black, titanium oxide, tin oxide, and zinc oxide. The average particle diameter of these conductive powders is preferably 1 (μm) or less. When the average particle diameter exceeds 1 (μm), it may be difficult to control electric resistance. The carrier resin layer is prepared, for example, by dissolving the silicone resin in a solvent to prepare a coating solution, and then uniformly coating the coating solution on the surface of the core by a known coating method, drying, and baking. It can form by performing. Examples of the application method include a dipping method, a spray method, and a brush coating method. The amount of the resin layer in the carrier is preferably 0.01 to 5.0 (% by mass). If the amount of the resin layer is less than 0.01 (% by mass), a uniform resin layer may not be formed on the surface of the core material. If the amount exceeds 5.0 (% by mass), the resin layer Becomes too thick and granulation of carriers occurs, and uniform carrier particles may not be obtained. The developer (initial agent) stored in advance in the developing device is also a mixture of the above-described toner and carrier. There is no restriction | limiting in particular as content (carrier density | concentration) of the carrier in a developing agent, According to the objective, it can select suitably. For example, 90-98 (mass%) is preferable and 93-97 (mass%) is more preferable.

<The principal part of Embodiment 1>
Hereinafter, the discharge ports 140 and 141 shown in FIG. 2 will be described with reference to FIGS. FIG. 4 is an external perspective view for explaining the toner replenishment position of the developing device 4. As shown in FIG. 4, the replenishment port 95 for replenishing the developer is provided above the downstream end in the transport direction of the supply transport path 9 including the supply screw 8. The developer replenishing port 95 is positioned above the surplus opening (arrow E in FIG. 3) of the second partition wall 134, so that the replenished developer is easily mixed with the surplus developer and the collected developer. The developer can be more efficiently stirred by replenishing with.

  Further, as shown in FIG. 4, a developer inlet 96 is disposed in the developing device 4. As shown in FIG. 5, the developing device 4 is covered with an inner cover 98 when the image forming apparatus is mounted, and is fixed so that only the developer inlet 96 is exposed. FIG. 6 shows a replacement developer storage container 97. As shown in FIG. 7, the developer charging port 96 and the supply port of the developer storage container 97 are coupled, the developing device is driven in this state, and the supply screw 8 in the developing device is rotated, so that the new developer is added. The developing device 4 is loaded.

  In this embodiment, a premix development method is employed. The excess developer is repaired by the developer overflowed from the supply screw 8 and the stirring screw 11 at the discharge ports 140 and 141 in FIG. 2, and is discharged by the screw disposed in the discharge ports 140 and 141. During normal operation, the screw disposed in the discharge port 140 is configured to rotate.

  FIG. 8 is a schematic diagram showing a configuration in the longitudinal direction inside the developing device 4. The surplus developer discharged after overflowing from the discharge port 149 is received in the surplus agent receiving chamber 140a. As shown in FIG. 8, the discharge port 140 is disposed at a high position with respect to the rotation axis of the supply screw 8, whereas the discharge port 141 is disposed at the same height with respect to the rotation shaft of the stirring screw 11. ing. By doing so, the developer is more easily discharged from the discharge port 141 than from the discharge port 140.

  The drive (not shown) of the screw disposed in the discharge port 141 is provided independently of the developing device drive, and the rotation On / Off can be arbitrarily set. During normal printing operation, the amount of developer replenished by the premix is very small per drive time, so that the excess developer is discharged even if the developing device volume is reduced by the immobile developer. The amount of the developer in the developing device is controlled stably without being in the closest packed state by discharging only from the above. However, when a new developer is introduced in a state where the effective volume is reduced, a large amount of developer is introduced in a short rotational drive time, so that the excess developer discharged from the discharge port 140 is sufficiently surplus. The developer cannot be handled, and the developer is in the closest packing state, and the developing device cannot be driven.

  Therefore, by adopting the configuration of the developing device, when the volume of the developing device is reduced due to the remaining of the stationary developer, the drive of the screw disposed in the discharge port 141 is turned on when the new developer is charged. Thus, the developer is discharged from both of the discharge ports 140 and 141, and the developer in the developing device can be prevented from being in the closest packing state. Further, when there is almost no stationary developer in the developing device and an effective developing device capacity is sufficiently secured, the developer conveying screw drive of the discharge port 141 is left off, which is unnecessary. Developer discharge can be prevented.

  By the way, as described above, it is possible to discharge the excess developer during the normal printing operation by providing a discharge port downstream of the supply screw 8 without affecting the developer supply amount to the developer device 4. It is. However, when the developer is charged when the effective volume of the developing device 4 is reduced, it is necessary to discharge the excess developer in a short time.

  In the present embodiment, as shown in FIGS. 2 and 8, two discharge ports 140 and 141 are provided in the supply conveyance path 9 and the agitation conveyance path 10, respectively. Unlike the case where two are arranged in the supply conveyance path 9, the reason why this embodiment is set as such is that the above case is taken into consideration. According to the present embodiment, surplus development can be discharged in a short time by the discharge port 141 in which the excess developer is more easily discharged than the discharge port 140, which affects the supply of the developer to the developing device 4. Does not reach.

  Further, the position where the discharge port 141 is arranged is a position where the developer tends to stay. By making it possible to change at least the discharge amount of the discharge port at this position, it is possible to efficiently discharge excess developer in a short time.

  Further, in the technical field of image forming apparatuses, there is a demand for further reduction in image printing cost. In order to reduce the operation stop time of the image forming apparatus due to regular maintenance, a user such as a toner replenishing container is required. There are an increasing number of devices that can easily replace parts. Generally, in a low-speed machine or the like, the developer is replaced with the developing device because the cost of the developing device is kept low. However, in a high-speed machine applied to production printing or the like, the developing device is configured to withstand high-speed operation, so that the developing device becomes expensive.

  Therefore, in the high speed machine, the developing device is removed from the image forming apparatus, and the developer in the developing device is removed. Since this work is a work around the image forming process and it is necessary to handle parts other than the developing device, work by a maintenance inspector is essential. In recent years, an image forming apparatus capable of discharging the developer in the developing apparatus and introducing a new developer in a state where the developing apparatus is mounted on the image forming apparatus has been put on the market in order to solve the problem. If the developing device is removed and the developer is replaced, it is possible to remove the immobile developer due to the deterioration of fluidity from the developing device by applying vibration to the removed developing device. However, when the developer is exchanged with the image forming apparatus mounted, it is difficult to apply vibration to the developing apparatus, and the stationary developer remaining in the developing apparatus cannot be removed.

  In the present embodiment, the developer inlet 96 as shown in FIGS. 4 to 7 is provided in the developing device 4, so that the developing device 4 can be attached to the image forming apparatus 500 without replacing and replacing the developing device 4. As a result, the developer can be changed. In this case, a developer discharge port similar to the discharge ports 140 and 141 is provided immediately below the developer supply port 96, and an empty developer storage container is connected to the developer discharge port when discharging the developer. It is preferable that the developer is discharged into an empty developer storage container by rotating the developer conveying screw in the developing device. In this case, it may be configured to determine the completion timing of charging and discharging based on the operating time of the developing device and the output value of the magnetic permeability sensor.

<Embodiment 2>
Next, the magnetic permeability sensor 142 in FIG. 8 will be described. In the present embodiment, a magnetic permeability sensor 142 is provided to detect the toner concentration in the developer in the developing device 4. Since the magnetic permeability sensor 142 detects the amount of magnetic material (carrier) per unit volume in the developer, it is possible to measure the bulk density of the developer. In the present embodiment, the toner density of the image forming apparatus is managed by measuring the correlation between the developer bulk density and the toner density in advance.

<Embodiment 3>
Further, the fluidity and bulk density of the developer have a correlation, and generally the fluidity tends to be poor when the bulk density is low. Therefore, it is possible to estimate the fluidity of the developer from the detection result of the magnetic permeability sensor 142 before introducing the new developer. In the present embodiment, the permeability sensor output is used in the range of 1V to 5V, and is adjusted so that the toner concentration center value of the developer to be used outputs 2.5V. The larger the output voltage of the magnetic permeability sensor 142, the larger the bulk density of the developer. In this embodiment, when the output of the magnetic permeability sensor is less than 1.5 V, it is set that discharge is possible from the discharge port 141 when the developer is subsequently replaced. With this setting, even when a new developer is introduced into the developing device 4, it is possible to prevent the development drive lock from occurring.

  In addition, it is possible to effectively prevent development drive lock by calculating the number of printed sheets as an alternative to the drive time of the developing device 4 and determining it together with the detection result. In the present embodiment, when the number of printed sheets driven at a magnetic permeability sensor output of 1.5 V or less is accumulated and the accumulated number of printed sheets is more than 5,000 pages, the developer is also discharged from the discharge port 141 when a new developer is introduced. Is controlled to be discharged.

<Embodiment 4>
Next, an apparatus for counting the amount of developer to be replenished will be described. In this embodiment, there is provided a device for calculating the amount of developer supplied from the developer cartridge to the developing device 4. Specifically, the drive time and supply amount of the developer supply device are measured in advance, the drive time of the developer supply device is counted, and the detection result is converted into the developer supply amount. By predicting the developer fluidity in the developing device from the developer replenishment amount per unit development driving time, and determining whether or not to discharge excess developer from the discharge port 141 when a new developer is charged, the developer is unnecessarily generated. It becomes possible to effectively prevent the drive lock of the developing device without discharging the toner.

<Example>
Hereinafter, examples based on the above embodiment will be described with reference to Table 1 and FIG. 9. Table 1 shows the result of confirming the presence or absence of the developing device drive lock when the developer is charged under predetermined control conditions. FIG. 9 shows the ratio of the amount of developer discharged to the total amount charged when the developer is charged.

  In Table 1 and FIG. 9, “Current Status” is a conventional image forming apparatus to which the configuration of the above embodiment is not applied. “Example 1” is based on the disclosure of the first embodiment (the contents of the second to fourth embodiments are not included). “Example 2” is based on the configuration based on the disclosure of the second embodiment in addition to the configuration of Example 1. “Example 3” is based on the configuration based on the disclosure of the third embodiment in addition to the configuration of Example 1. “Example 4” is based on the configuration based on the disclosure of the fourth embodiment in addition to the configuration of Example 1.

  As is apparent with reference to Table 1 and FIG. 9, the developing device drive lock can be prevented beforehand by supplying the developer under the control conditions of Examples 1 to 4. Further, by adopting the determination conditions of the other embodiments as compared with the discharge under the conditions of the first embodiment, it is possible to prevent the developing device drive lock while suppressing unnecessary developer discharge.

  According to the above-described embodiment, it is possible to provide an image forming apparatus in which the developer can be easily replaced while preventing troubles such as abnormal rotation of the developing apparatus, even in an image forming apparatus in any usage situation. Regardless of the usage history of the developing device, it becomes possible to reliably prevent the development driving lock immediately after the developer replacement.

DESCRIPTION OF SYMBOLS 4 Developing device 5 Developing roller 6 Collection screw 7 Collection conveyance path 8 Supply screw 9 Supply conveyance path 10 Stirring conveyance path 11 Stirring screw 95 Developer supply port 96 Developer inlet 97 Replacement developer storage container 98 Inner cover 140 Discharge port 140a Surplus agent receiving chamber 141 Discharge port 142 Magnetic permeability sensor

JP 2011-145465 A JP 2009-058939 A

Claims (7)

A developing device;
Replenishing means for replenishing toner or carrier as a component of the developer into the developing device;
A storage chamber for storing a developer;
An overflow opening provided in a wall of the storage chamber so as to overflow the developer in the storage chamber;
Two or more overflow openings are provided,
A first overflow opening, at least one of which is
An excess agent receiving chamber for receiving excess developer overflowing from the first overflow opening;
Discharging means for discharging the excess developer in the excess agent receiving chamber to the outside,
The image forming apparatus, wherein the discharge unit is in a dischargeable state at a predetermined timing.   The image forming apparatus according to claim 1, wherein the developer can be replenished by at least one of the replenishing units while the developing device is mounted on the image forming apparatus.   The image forming apparatus according to claim 1, wherein the first overflow opening has a larger developer discharge amount than the other overflow openings. The storage chamber is divided into at least two transport paths;
4. The image forming apparatus according to claim 1, wherein the first overflow opening is arranged in a conveyance path upstream of a conveyance path in which another overflow opening is arranged. 5. .   5. The image forming apparatus according to claim 1, wherein the developing device includes a magnetic permeability sensor, and determines a driving state of the discharge unit based on a detection result of the magnetic permeability sensor. apparatus.   6. The image forming apparatus according to claim 1, further comprising a unit that counts a driving time of the developing device, and determining a driving state of the discharging unit based on the counting result. .   7. The apparatus according to claim 1, further comprising a unit that counts a developer replenishment amount from the replenishing unit, and determining a driving state of the discharging unit based on the counting result. Image forming apparatus.

Images