JP5277587B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing apparatus capable of supplying developer into a latent image carrier stably by preventing the developer from being discharged irrespective of amount of developer in the developing apparatus being not increased because the jumping up developer is discharged. <P>SOLUTION: This developing apparatus 4 is provided with a developer discharge port 94 for discharging the developer to the outside of this apparatus at the predetermined height in a position where amount of developer is increased or decreased in accordance with increase or decrease of amount of developer in the whole developer conveyance passage in the developer conveyance passage. This developing apparatus 4 is also provided with a discharge port opening and closing member 140 being movable in the vertical direction, closing the developer discharge port 94 when positioned in a lower part, and opening the discharge port 94 when positioned in an upper part. This developing apparatus 4 prevents the discharge of the developer jumping up due to conveyance operation of a developer conveyance member when a level of the developer surface is low and opens the opening and closing member naturally by pressure of the developer without requiring any special driving source such as a motor or the like when a level of the developer surface exceeds the predetermined height to prevent the discharge of the developer from being obstructed. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an image forming apparatus used for a copying machine, a facsimile, a printer, and the like.

Conventionally, an image forming apparatus including a developing device using a two-component developer including toner and a magnetic carrier has been widely used. As an image forming apparatus of this type, the toner density of the developer is kept within a predetermined range by supplying toner from the toner container as necessary to the developer in the developing apparatus that consumes toner with development. There is something to keep in. In such a configuration, the carrier in the developer is hardly consumed and is repeatedly used. As the image is output, the coat layer on the surface of the carrier wears out, and conversely, toner resin and additives adhere to the coat layer. To do.
As a result, the ability of the carrier to charge the toner gradually decreases, and the carrier is in a deteriorated state. As the deterioration of the carrier progresses, the charge amount of the toner decreases, causing background stains and toner scattering. Therefore, in this type of image forming apparatus, a service person visits the user regularly to replace the carrier. . For this reason, maintenance costs are incurred, and the unit price for image formation is high.

Patent Document 1 discloses a developing device that discharges an increased amount of developer from the developing device while replenishing the developer in the developing device with a premix developer in which a carrier and toner are mixed to recover the toner concentration. Is described. In such a configuration, a new carrier in the premix developer is replenished to the developer in the developing device while the carrier that has become old due to the discharge of the developer is gradually discharged from the developing device. Then, the carrier replacement work can be omitted by replacing the carrier in the developer gradually with a new one by such discharge and replenishment.
Further, in the developing device of Patent Document 1, the developer discharge for discharging the developer to the outside at a predetermined height at a position where the bulk of the developer increases or decreases according to the increase or decrease of the developer amount in the entire developer transport path. Has an exit. In this developing device, when the premix developer is replenished and the amount of developer in the developing device increases, the bulk of the developer in the supply conveyance path increases. At this time, the developer reaching the height of the developer discharge port at the position where the developer discharge port is provided is discharged from the developer discharge port to the outside of the developing device.

However, when the developer transported in the developer transport path moves, or when the transport member that imparts transport force to the developer is a developer transport screw, the developer jumps by the rotating force, etc. It may be discharged from the developer outlet. When the jumped developer is discharged, even if the developer transported in the developer transport path is in an appropriate amount or less than the proper amount, the jumped developer may be discharged. is there. This is a state in which the developer is discharged even though the amount of developer in the developing device has not increased. If the developer is discharged from the developer discharge port even though the developer is in an appropriate amount or less, the amount of developer in the developing device falls below the required amount, and the development on the latent image carrier is performed. The supply of the agent might become unstable. When the supply of the developer to the latent image carrier becomes unstable, an abnormal image such as missing image occurs.
Such a problem is not limited to the developing device using the two-component developer, but the developer is replenished by the developer replenishing means, and the amount of the developer in the developing device is increased by the developer discharging means. This is a problem that may occur even in a developing device that uses a one-component developer as long as the developing device has a configuration for discharging.

JP 2005-292511 A

  Therefore, the present invention has been made in view of the above problems, and the problem is that the developer is discharged even though the jumped developer is discharged and the amount of developer in the developing device is not increased. Accordingly, it is an object of the present invention to provide a developing device that can stably supply a developer to a latent image carrier and an image forming apparatus including the developing device.

The features of the present invention, which is a means for solving the above problems, are listed below.
In order to achieve the above object, the developing device of the present invention carries a developer on the surface, rotates, and supplies toner to the latent image on the surface of the latent image carrier at a position facing the latent image carrier. a developer carrying member for developing and includes a developer conveying member for conveying the developer while supplying the developer to the developer carrier in a developer supply region for supplying the developer to the developer carrying member a developer conveying path for conveying the developer, and a developer supply means for supplying a developer to the developer conveyance path, the bulk of the developer according to the overall developer conveying path developer increase and decrease a position a predetermined height but increasing or decreasing, a closed state in which the developer discharge port for discharging the developer to the outside of the apparatus Te developing device smell provided in the developer transport path, closing the developer discharge opening, wherein A discharge port opening / closing member that can be changed to an open state in which the developer discharge port is opened is provided. The opening / closing member is movable up and down, closes the developer discharge port when it is below, opens the developer discharge port when it is above, and is biased downward, and the biasing force is A partition wall that is set smaller than the developer pressure applied to the discharge port opening and closing member when the developer increases, has a wall surface facing the developer discharge port, and has a partition wall that faces the developer discharge port. The discharge port opening / closing member is fixed below the developer discharge port, and the developer opening side end of the partition wall reaches the wall surface of the developer discharge port side to cover the developer surface. by are, when the low developer surface performs discharge prevention of the developer flies by the conveying operation of the developer conveying member, a special drive of the motor or the like if the developer surface exceeds a predetermined height sources without requiring naturally by the developer pressure Closed part material is opened, Ru der those characterized by that does not inhibit the discharge of developer.
The developing device of the present invention further includes a guide provided in a direction perpendicular to the developer surface. When the developer volume is low, the discharge opening / closing member moves downward along the guide. covers the developer surface, Ru der which is characterized in that if the developer bulky which opens the developer outlet by opening and closing member by the developer pressure moves upward along the guide .

The developing device of the present invention carries a developer on the surface, rotates, supplies the toner to the latent image on the surface of the latent image carrier and develops it at a location facing the latent image carrier. If, comprising a developer conveying member for conveying the developer, the developer carrier to the developer bearing member while supplying the developer to convey the developer the developer conveyed by the developer supply region for supplying the developer and a road, wherein the developer predetermined height position bulk increases or decreases of the developer in accordance with the conveyance path overall amount of developer increases or decreases, the developer discharge opening for discharging the developer from the apparatus in the developing device provided in the developer conveyance path, wherein comprising a closed state to close the developer discharge port, an outlet closing member possible changes to the open state for release to open the developer discharge port, the discharge port opening member is fixed to fall outside direction of the developer discharge port was increased By the fact that the developer discharge port is opened when said discharge opening and closing member by the pressure of the image agent fallen, in the absence of pressure of the developer of the developer flies by the conveying operation of the developer conveying member to prevent discharge, fall over naturally the outlet closing member when the pressure of the developer is increased, it is characterized in that to take an open state.
Further, by the outlet closing member is to allow opening and closing the top as a fulcrum, and is characterized in that to prevent the closing of the exhaust outlet opening and closing member is inhibited by the discharged developer.
Further, the developer discharge port is located above the normal developer surface , thereby preventing the developer from being discharged more than necessary when the discharge port opening / closing member fails.

The image forming apparatus of the present invention includes: a latent image carrier even without low, a charging unit for charging the latent image bearing member surface, for forming an electrostatic latent image on said image bearing member in the image forming apparatus having a latent image forming means, a developing means for toners Zoka to develop the electrostatic latent image, as the developing unit, der which comprises using the above-described developing device The

By the means to solve the above, it is possible to prevent the developer from being discharged even if the amount of the developer in the developing device is not increased without using a special drive source such as a motor. The required amount of developer in the apparatus can be secured, and there is an excellent effect that a stable developer can be supplied to the latent image carrier.

The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.
Hereinafter, as an image forming apparatus to which the present invention is applied, an embodiment (hereinafter simply referred to as “embodiment”) of a tandem type color laser copying machine (hereinafter simply referred to as “copying machine”) in which a plurality of photoconductors are arranged in parallel. ").
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. The copier includes a printer unit 100, a paper feeding device 200 on which the printer unit 100 is placed, a scanner 300 fixed on the printer unit 100, and the like. An automatic document feeder 400 fixed on the scanner 300 is also provided.

The printer unit 100 includes an image forming unit including four sets of process cartridges 18Y, M, C, and K 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 indicate the members for yellow, cyan, magenta, and black (the same applies hereinafter). In addition to the process cartridges 18Y, M, C, and K, an optical writing unit 21, an intermediate transfer unit 17, a secondary transfer device 22, a resist roller pair 49, a belt fixing type fixing device 25, and the like are disposed. .
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 the surface of a photoreceptor to be described later with laser light based on image data.
The process cartridges 18Y, 18M, 18C, and 18K include a drum-shaped photosensitive member 1, a charger, a developing device 4, a drum cleaning device, a static eliminator, and the like.

The yellow process cartridge 18Y will be described below.
The surface of the photoreceptor 1Y is uniformly charged by a charger as charging means. The surface of the photoreceptor 1 </ b> Y that has been subjected to charging processing is irradiated with laser light that has been modulated and deflected by the optical writing unit 21. Then, the potential of the irradiation part (exposure part) is attenuated. By this attenuation, 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 as developing means 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 described later. The surface of the photoreceptor 1Y after the primary transfer is cleaned of the transfer residual toner by a drum cleaning device.
In the Y process cartridge 18Y, the photoconductor 1Y cleaned by the drum cleaning device is discharged by the charge eliminator. Then, it is uniformly charged by the charger and returns to the initial state. The series of processes as described above is the same for the other process cartridges 18M, C, and K.

Next, the intermediate transfer unit will be described.
The intermediate transfer unit 17 includes an intermediate transfer belt 110, a belt cleaning device 90, and the like. In addition, the tension roller 14, the driving roller 15, the secondary transfer backup roller 16, four primary transfer bias rollers 62Y, M, C, and K are also provided.
The intermediate transfer belt 110 is tensioned by a plurality of rollers including the tension roller 14. Then, it is endlessly moved clockwise in the drawing by the rotation of the driving roller 15 driven by a belt driving motor (not shown).
The four 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 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 photosensitive member and the primary transfer bias roller due to the influence of the primary transfer bias.
The above-described Y toner image formed on the Y photoconductor 1Y is primarily transferred onto the intermediate transfer belt 110 due to the influence of the primary transfer electric field and nip pressure. On the Y toner image, the M, C, and K toner images formed on the M, C, and K photoconductors 1M, 1C, and 1K are sequentially superimposed and primarily transferred. By this primary transfer of superposition, a four-color superposed toner image (hereinafter referred to as a four-color toner image) that is 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 90 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 is moved endlessly in the counterclockwise direction in the drawing in accordance with the rotational drive of at least one of the stretching rollers 23. One of the two stretching rollers 23 arranged on the right side in the drawing sandwiches the intermediate transfer belt 110 and the paper transport belt 24 between the secondary transfer backup roller 16 of the intermediate transfer unit 17. It is out. 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 stretching roller 23 by a power source (not shown). By applying this secondary transfer bias, the four-color toner image on the intermediate transfer belt 110 of the intermediate transfer unit 17 is electrostatically moved from the belt side toward the one stretching roller 23 side in the secondary transfer nip. A next transfer electric field 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 to be 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 one of the stretching rollers 23 as described above, 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 main body, a plurality of paper feeding cassettes 44 in which a plurality of transfer sheets can be stacked and accommodated in a bundle of sheets are arranged so as to overlap in the vertical direction. Has been. 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 46.
The paper feed path 46 that receives the transfer paper fed from the paper feed cassette 44 has a plurality of conveying roller pairs 47 and a registration roller pair 49 provided near the end in the path. 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 moves the fixing belt 26 endlessly while being stretched by two rollers, 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 pressurizes the fixing belt 26 by the generated heat. The pressed 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. To the secondary transfer nip described above.

When a copy of the document, not shown, is taken, for example, a bundle of document sheet is Se Tsu bets on a 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. However, 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 start driving. Based on the image information constructed by the reading sensor 36, the optical writing unit 21 is driven and controlled, and Y, M, C, and K toner images are formed on the respective photoreceptors 1Y, 1M, 1C, and 1K. Is done. 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 sheets are separated one by one by the separation roller 45 and enter the reverse feeding path 48 , and then conveyed toward the secondary transfer nip by the conveying 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 another color image composed of two or more colors of toner, the copying machine stretches the intermediate transfer belt 110 so that the upper stretched surface thereof is substantially horizontal, 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 from each other. 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 is stopped to prevent unnecessary consumption of the photosensitive member and the developer.
The copying machine includes a control unit (not shown) configured by a CPU or the like that controls the following devices in the copying machine, and an operation display unit (not shown) configured by a liquid crystal display, various key buttons, and the like. The operator sends a command to the control unit by a key input operation on the operation display unit, so that one of the three modes is selected from the three-sided print mode, which is a mode for forming an image only on one side of the transfer paper. You can choose one. The three single-sided printing modes include a direct discharge mode, a reverse discharge mode, and a reverse decal discharge mode.

FIG. 2 is an enlarged configuration diagram showing a developing device and a photosensitive member included in one of the four process cartridges 18Y, M, C, and K. 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. Therefore, Y, M, C, and K indicated by “4” in FIG. Subscripts are omitted.
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. The charged surface of the photoreceptor 1 is supplied with toner from the developing device 4 to a latent image on which an electrostatic latent image is formed by laser light emitted from an exposure device (not shown), thereby forming a toner image.
The developing device 4 has a developing roller 5 as a developer carrying member for supplying toner to the latent image on the surface of the photoreceptor 1 while moving the surface in the direction of arrow I in the drawing. Further, a supply screw 8 is provided as a supply conveyance member that conveys the developer in the depth direction of FIG. 2 while supplying the developer to the developing roller 5. The supply screw 8 is a developer conveying screw that includes a rotating shaft and a blade portion provided on the rotating shaft and conveys the developer in the axial direction by rotating.
A developing doctor 12 as a developer regulating member for regulating the developer supplied to the developing roller 5 to a thickness suitable for development is provided on the downstream side of the surface moving direction from the portion facing the supply screw 8 of the developing roller 5. ing.
The developed developer that has passed through the developing section is collected downstream from the developing section, which is the facing portion of the developing roller 5 with respect to the photoconductor 1, and the collected developer is collected in the same direction as the supply screw 8. A recovery screw 6 is provided as a recovery transport member for transporting to the front. A supply conveyance path 9 including a supply screw 8 is provided in the lateral direction of the developing roller 5, and a recovery conveyance path 7 serving as a recovery conveyance path including the recovery screw 6 is provided below the development roller 5.

The developing device 4 is provided with a stirring conveyance path 10 in parallel with the collection conveyance path 7 below the supply conveyance path 9. The agitating and conveying path 10 includes an agitating screw 11 serving as an agitating and conveying member that conveys the developer to the near side in the figure, which is the direction opposite to the supply screw 8 while stirring the developer.
The supply conveyance path 9 and the stirring conveyance path 10 are partitioned by a first partition wall 133 as a partition member. In the first partition wall 133, the supply conveyance path 9 and the agitation conveyance path 10 are partitioned at both ends on the front side and the back side in the drawing, and the supply conveyance path 9 and the agitation conveyance path 10 communicate with each other. doing.
The supply conveyance path 9 and the recovery conveyance path 7 are both partitioned by the first partition wall 133, but an opening is provided at a location where the supply conveyance path 9 and the recovery conveyance path 7 of the first partition wall 133 are partitioned. Absent.
Further, the two conveyance paths of the stirring conveyance path 10 and the collection conveyance path 7 are partitioned by a second partition wall 134 as a partition member. The second partition wall 134 has an opening on the front side in the figure, and the agitation transport path 10 and the collection transport 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, and each screw has a diameter of φ22 [mm] and the screw pitch is 50 [mm]. The winding, the recovery screw 6 and the stirring screw 11 are one roll of 25 [mm], and the number of rotations is all set to about 600 [rpm].
The developer thinned by the developing doctor 12 made of stainless steel on the developing roller 5 is transported to a developing area which is a portion facing the photosensitive member 1 for development. The surface of the developing roller 5 is V-groove or sandblasted and is made of an Al or SUS base tube of φ25 [mm], and the gap between the developing doctor 12 and the photoreceptor 1 is about 0.3 [mm].
The developer after the development is collected in the collection conveyance path 7, conveyed to the front side of the cross section in FIG. 2, and to the agitation conveyance path 10 through the opening of the first partition wall 133 provided in the non-image area portion. Developer is transferred. The toner is supplied to the stirring and conveying path 10 from the toner supply port provided on the upper side of the stirring and conveying path 10 near the opening of the first partition wall 133 on the upstream side in the developer conveying direction in the stirring and conveying path 10.

Next, the circulation of the developer in the three developer conveyance paths will be described.
FIG. 3 is a perspective sectional view of the developing device for explaining the flow of the developer in the developer transport path. Each arrow in the figure indicates the moving direction of the developer.
FIG. 4 is a schematic diagram of the developer flow in the developing device. Each arrow in the figure indicates the moving direction of the developer.
In the supply conveyance path 9 that has been supplied with the developer from the agitation conveyance path 10, the developer is conveyed downstream in the conveyance direction of the supply screw 8 while supplying the developer to the developing roller 5. Then, the excess developer that is supplied to the developing roller 5 and is not used for development and is transported to the downstream end in the transport direction of the supply transport path 9 is supplied to the stirring transport path 10 from the surplus opening 92 of the first partition wall 133 ( Arrow E) in FIG.
The collected developer that is sent 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 is supplied to the stirring conveyance path 10 from the collection opening 93 of the second partition wall 134. (Arrow F in FIG. 4).
The agitating and conveying path 10 agitates the supplied surplus developer and the recovered developer, conveys the agitating screw 11 to the downstream side in the conveying direction, and conveys it to the upstream side in the conveying direction of the supplying screw 8. It is supplied to the supply conveyance path 9 from the supply opening 91 of 133 (arrow D in FIG. 4).
In the agitating and conveying path 10, the agitating screw 11 agitates and conveys the collected developer, the surplus developer, and the toner replenished as necessary in the transfer unit in the direction opposite to the developer in the collecting and conveying path 7 and the supply conveying path 9. . Then, the agitated developer is transferred to the upstream side in the conveyance direction of the supply conveyance path 9 communicating with the downstream side in the conveyance direction. A toner concentration sensor (not shown) is provided below the agitation transport path 10, and a toner supply control device (not shown) is operated by the sensor output to supply toner from a toner storage portion (not shown).

In the developing device 4 shown in FIG. 4, 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 the developed developer is supplied to the supply conveyance path 9. There is no contamination. Accordingly, it is possible to prevent the toner density of the developer supplied to the developing roller 5 from decreasing 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. Therefore, since the sufficiently agitated developer is supplied to the supply conveyance path 9, it is possible to prevent the developer supplied to the supply conveyance path 9 from being insufficiently agitated. In this way, the toner density of the developer in the supply conveyance path 9 can be prevented from decreasing, and the developer in the supply conveyance path 9 can be prevented from being insufficiently stirred. Can be constant.
As shown in FIG. 4, the developer moves from the lower part to the upper part of the developing device 4 only by the arrow D. The movement of the developer indicated by an arrow D is to push the developer by rotating the stirring screw 11 so that the developer is raised and supplied to the supply conveyance path 9.
Such movement of the developer gives stress to the developer and contributes to a decrease in the life of the developer.
When the developer is lifted from the bottom to the top, stress is applied to the developer, and the carrier film in the developer is scraped off and the toner is spent on the spot. Accordingly, the stability of the image quality is maintained. It will disappear.
Therefore, the life of the developer can be extended by reducing the stress of the developer in the movement of the developer indicated by the arrow D. By prolonging the life of the developer, it is possible to provide a developing device that prevents deterioration of the developer and is always stable in image quality without image density unevenness.

In the developing device 4 of the embodiment, as shown in FIG. 2, the supply conveyance path 9 is disposed obliquely above the stirring conveyance path 10. By disposing it obliquely above, it is possible to reduce the developer stress in the movement of the developer indicated by the arrow D, compared to the case where the supply conveyance path 9 is provided vertically above the stirring conveyance path 10 and the developer is lifted. .
Further, in the developing device 4, the supply conveyance path 9 and the agitation conveyance path 10 are arranged obliquely so that the upper wall surface of the agitation conveyance path 10 is higher than the lower wall surface of the supply conveyance path 9 as shown in FIG. 2. It arranges so that it may become a position.
Lifting the supply conveyance path 9 vertically upward with respect to the stirring conveyance path 10 causes the developer to be stressed because the developer is lifted by the pressure of the stirring screw 11 against gravity. On the other hand, the developer present at the highest point of the agitating and conveying path 10 is placed at the bottom of the supplying and conveying path 9 by arranging the upper wall surface of the agitating and conveying path 10 to be higher than the lower wall surface of the supplying and conveying path 9. Since the point can flow without being against gravity, the stress applied to the developer can be reduced.
Note that a fin member may be provided on the shaft of the stirring screw 11 in a portion where the stirring transport path 10 and the supply transport path 9 communicate with each other on the downstream side of the developer transport path of the stirring transport path 10. This fin member is a plate-like member composed of a side parallel to the axial direction of the stirring screw 11 and a side perpendicular to the axial direction of the stirring screw. By scooping up the developer with this fin member, it is possible to more efficiently deliver the developer from the stirring conveyance path 10 to the supply conveyance path 9.
Further, in the developing device 4, the distance between the center A between the developing roller 5 and the supply conveyance path 9 is shorter than the distance B between the center between the development roller 5 and the agitation conveyance path 10. A conveyance path 10 is arranged. Thus, the developer can be supplied without difficulty from the supply conveyance path 9 to the developing roller 5, and the apparatus can be reduced in size.
Further, the stirring screw 11 is rotated counterclockwise as viewed from the front side in FIG. 2 (the direction of arrow C in the figure), and the developer is supplied by lifting the developer along the shape of the stirring screw 11. It is transferred to the conveyance path 9. As a result, the developer can be lifted efficiently, and the stress on the developer can be further reduced.

FIG. 5 is an explanatory cross-sectional view of the cross-section at the rotation center of the supply screw of the developing device as seen from the direction of arrow J in FIG. In the figure, H denotes a developing region in which the developing roller 5 that is a developer carrying member supplies toner to the photosensitive member 1 that is a latent image carrying member. The width in the axial direction of the rotation axis of the developing roller 5 in the developing area H is the developing area width α.
As shown in FIG. 5, the developing device 4 has a supply opening 91 that is a part for lifting the developer from the agitation conveyance path 10 to the supply conveyance path 9, and a surplus that drops the developer from the supply conveyance path 9 to the agitation conveyance path 10. Both of the openings 92 are provided in the development region width α.

FIG. 6 is a schematic diagram of the developer flow in the developing device having a configuration different from that in FIG. 4.
The developing device 4 shown in FIG. 6 is provided with a supply opening 91 and a surplus opening 92 outside the developing region width α. Since the supply opening 91 is provided outside the developing region width α, the upstream side in the transport direction of the supply transport path 9 is longer than the developing roller 5 by the upstream region β of the supply transport path. Further, since the surplus opening 92 is provided outside the developing region width α, the downstream side in the transport direction of the supply transport path 9 is longer than the developing roller 5 by the region γ on the downstream side of the supply transport path.
On the other hand, in the developing device 4 having the configuration shown in FIG. 4, since the supply opening 91 is provided within the developing region width α, the upstream side in the transport direction of the supply transport path 9 is on the supply transport path than the developing device 4 in FIG. The flow side region β can be shortened. Further, since the surplus opening 92 is provided in the developing area width α, the downstream side in the transport direction of the supply transport path 9 can be made shorter by the area γ on the downstream side of the supply transport path than the developing device 4 in FIG.
4 is provided with the supply opening 91 and the surplus opening 92 within the developing region width α, the upper portion of the developing device 4 is higher than that of the developing device 4 shown in FIG. Space saving can be achieved.

Next, the position at which toner is supplied to the developer conveyance path including the supply conveyance path 9, the agitation conveyance path 10 and the collection conveyance path 7 of the developing device 4 will be described. FIG. 7 is an external perspective view of the developing device.
As shown in FIG. 7, a toner replenishing port 95 for replenishing toner is provided above the upstream end of the agitating and conveying path 10 including the agitating screw 11 in the conveying direction. Since the toner replenishing port 95 is provided outside the end portion in the width direction of the developing roller 5, it is outside the developing region width α.
The portion where the toner replenishing port 95 is provided is on an extension line in the conveyance direction of the supply conveyance path 9 and corresponds to a vacant space in the region γ on the downstream side of the supply conveyance path in FIG. Providing the toner replenishment port 95 in an empty space by providing the surplus opening 92 within the developing region width α makes it possible to reduce the size of the developing device 4.
Further, the toner replenishing port 95 is not limited to the position above the upstream end portion in the transport direction of the stirring transport path 10 and may be provided above the downstream end portion of the collection transport path 7.
Further, a toner replenishing port 95 may be provided directly above the collection opening 93 where the developer is transferred from the collection conveyance path 7 to the stirring conveyance path 10. Since the space directly above the collection opening 93 is also an empty space provided by providing the surplus opening 92 within the developing region width α, the toner replenishing port 95 is provided at this position to reduce the size of the developing device 4. Can be planned. Furthermore, since the recovery opening 93 developer is easily mixed it is transfer unit, and more to perform replenishment at this position, it is possible to agitate a more efficient developer.

As in the developing device 4 described with reference to FIG. 4, a supply opening 91 that transfers the developer from the downstream end in the transport direction of the stirring transport path 10 to the upstream end in the transport direction of the supply transport path 9, and the supply transport path 9 Since the surplus opening 92 for transferring the developer from the downstream end to the upstream end in the transport direction of the stirring transport path 10 is provided in the development region width α, the upper portion of the development device 4 is higher than the conventional development device 4. Space can be saved, and the space of the entire developing device 4 can be saved.
Also, by providing the toner replenishment port 95 in the empty space by providing the surplus opening 92 within the development region width α, the development device 4 can be downsized.
Also, more from above the recovery opening portion 93 is a delivery portion of the developer to the stirring conveyance path 10 from the collection conveyance path 7 to supply toner, it is possible to agitate a more efficient developer.
Further, by providing the developing device 4 as the developing means of the printer unit 100 of the copying machine as the image forming apparatus, it is possible to save the space of the entire apparatus.

Next, replacement of the developer in the developing device 4 will be described.
A toner replenishment control device (not shown) that is a developer replenishing unit replenishes toner in a toner storage unit (not shown) to the developing device 4 from the toner replenishing port 95. In the developing device 4 of the embodiment, a developer including toner and a carrier is supplied from a toner supply port 95 of the developing device 4. Hereinafter, the developer in which the toner supplied to the developing device 4 and the carrier are mixed is referred to as premix toner.
Further, in the supply conveyance path 9, when the developer in the supply conveyance path 9 exceeds a predetermined volume, a developer discharge port 94 for discharging a part thereof to the outside of the developing device 4 and a developer discharge port 94. And a discharge conveyance path 2 provided with a discharge conveyance screw 2a for conveying the developer discharged from the developing device 4 to the outside. The discharge conveyance path 2 is disposed on the downstream side in the conveyance direction of the supply conveyance path 9 so as to be adjacent to the supply conveyance path 9 with the partition wall 135 interposed therebetween, and the developer discharge port 94 is connected to the supply conveyance path 9 and the discharge conveyance path 2. Is an opening provided in the partition wall 135 so as to communicate with each other.

Next, the conventional developing device 4 provided with the developer discharge port 94 will be described.
FIG. 16 is a cross-sectional explanatory view of the developing device 4 in the vicinity of the downstream end in the transport direction of the supply transport path 9 as viewed from the same direction as in FIG. 2 for the conventional developing device 4 provided with the developer discharge port 94.
The vicinity of the downstream end of the supply conveyance path 9 in the conveyance direction is, for example, the same position in the conveyance direction of the developer conveyance section 9 and the supply conveyance path 9 where the developer is transferred from the supply conveyance path 9 to the stirring conveyance path 10. It is a place.
The rotation direction of the supply screw 8 in the supply conveyance path 9 is clockwise (direction of arrow M) in FIG. 8 described later, and the developer is supplied to the developing roller 5 by lifting it from below. It is rotating in the direction you want. Here, when the developer is supplied to the developing roller 5 so that the rotation direction of the supply screw 8 is counterclockwise and the developer is sprinkled from above, the developer is supplied to the developing roller 5 while being scattered. On the other hand, when the rotation direction of the supply screw 8 is clockwise as shown in FIG. 8, the developer is supplied to the developing roller 5 so as to lift the developer from below the supply conveyance path 9 in which the developer is accumulated. It becomes like this. Since the developer supply performance is more stable when the developer is supplied from the lower side than when the developer is supplied while being scattered, the rotation direction of the supply screw 8 is set clockwise in FIG. doing.
In particular, in the case where the developer supplied to the developing roller 5 is not returned to the supply conveyance path 9 but is collected to the collection conveyance path 7 as in the developing device 4 of this embodiment, the amount of developer goes downstream of the supply conveyance path 9. It decreases according to. For this reason, it is more excellent in terms of developer supply that the developer is drawn up from below and supplied to the developing roller 5.

Here, the developer in the supply conveyance path 9 jumps by the momentum of movement in the supply conveyance path 9 by being conveyed and the rotating force of the supply screw 8 that is a developer conveyance screw. As shown in FIG. 16, when the developer discharge port 94 is simply provided at a predetermined height of the supply conveyance path 9 that is a developer conveyance path, as indicated by an arrow T in FIG. 16. On the path, the jumped developer may fly and pass through the developer discharge port 94 and be discharged. When the developer jumps and is discharged, even if the developer transported through the position where the developer discharge port 94 in the supply transport path 9 is provided is in an appropriate amount or less than the appropriate amount, The jumped developer may be discharged. In such a state where the developer jumped off is discharged, the developer may be discharged from the developer discharge port even though the amount of the developer in the developing device 4 is not more than an appropriate amount. The amount of developer in the developing device 4 is less than the required amount, and the supply of developer to the photoreceptor 1 may become unstable. When the developer supply to the photosensitive member 1 becomes unstable, an abnormal image such as image omission occurs.
In FIG. 16, the arrow T indicates the path of the jumped developer toward the developer discharge port 94. The arrow T schematically shows the path of the jumped developer toward the developer discharge port 94, and the path of the jumped developer toward the developer discharge port 94 is limited to that indicated by the arrow T. is not.

[Example 1]
Next, a first example (hereinafter referred to as “Example 1”) including the characteristic portion of the developing device 4 of the embodiment will be described.
FIG. 8 is an explanatory cross-sectional view of the developing device 4 according to the first embodiment, and shows a state where the discharge port opening / closing member 140 is closed. FIG. 9 is a cross-sectional explanatory view of the developing device 4 of the first embodiment, showing a state where the discharge port opening / closing member 140 is opened.
As illustrated in FIG. 8, the developing device 4 according to the first exemplary embodiment is configured such that the developer flying as the supply screw 8 that is a developer conveying member rotates to convey the developer travels toward the developer discharge port 94. A discharge port opening / closing member 140a for closing (arrow T in FIG. 16) is provided. The discharge port opening / closing member 140 a is supported at its end by a wall surface 141 a facing the developer discharge port 94, so that the discharge port opening / closing member 140 a can block the developer discharge port 94. The discharge port opening / closing member 140a is formed of an elastic body or a rigid body. When the elastic body is used, the support portion 143 is fixed, and the discharge port opening / closing member 140a is a cantilever. Further, when the discharge port opening / closing member 140a is a rigid body, the support portion 143 is freely rotatable. Regardless of whether the discharge port opening / closing member 140a is a rigid body or an elastic body, when the agent interface 142 is lower than the developer discharge port 94, the developer flying over by the rotation of the supply screw 8 is developed by covering the upper portion of the agent interface. The path (arrow T in FIG. 16) toward the agent discharge port 94 is blocked.
FIG. 9 shows a case where the discharge port opening / closing member 140a is a rigid body. Thus, when the agent interface 142 becomes higher than the developer discharge port 94, the discharge port opening / closing member 140a is opened by being pushed up by the developer. In this state, the developer can be discharged through the developer discharge port 94.
Thus, by opening and closing the path toward the developer discharge port 94 according to the height of the agent interface 142, the jumped developer is prevented from being discharged, and the amount of developer in the developing device 4 is increased. It is possible to prevent the developer from being discharged despite the absence of the developer. Therefore, the necessary amount of developer in the developing device 4 can be secured, and the developer can be stably supplied to the photoreceptor 1. As a result, the electrostatic latent image on the photoreceptor 1 can be favorably converted into a toner image, an abnormal image such as image omission can be prevented, and good image formation can be performed.

In the developing device 4, when the premix toner is supplied into the developing device 4 by a toner supply control device (not shown) and the amount of developer in the developing device 4 increases, the supply conveying path 9 near the downstream end in the conveying direction. The bulk of the developer increases.
Hereinafter, it will be described that as the amount of developer in the developing device 4 increases, the bulk of the developer near the downstream end in the transport direction of the supply transport path 9 increases.
In the developing device 4, the trend of the developer is caused by a change in the amount of developer transported by the stirring screw 11 when the premix toner is replenished or a change in the amount of developer delivered from the stirring transport path 10 to the supply transport path 9. Different.
For example, when the amount of developer transported by the stirring screw 11 does not change so much while the premix toner is supplied, the amount of developer supplied upstream in the transport direction of the supply transport path 9 does not change much. Even when the configuration in which the developer is delivered from the agitation conveyance path 10 to the supply conveyance path 9 is close to the upper limit of the amount that can be delivered when the developer is not replenished, the supply conveyance path 9 in the conveyance direction upstream side The amount of developer supplied to the toner does not change much.

In the developing device 4 having such a configuration, even when the premix toner is replenished, the amount of developer conveyed through the supply conveyance path 9 does not change, and the amount of developer supplied from the supply conveyance path 9 to the developing roller 5 is changed. Therefore, the amount of the developer reaching the vicinity of the downstream end in the transport direction of the supply transport path 9 per time by the supply screw 8 hardly changes.
On the other hand, when the conveyance amount of the agitation conveyance path 10 does not change much, when the premix toner is replenished from the toner replenishing port 95, the increased developer stays in the vicinity of the upstream end of the agitation conveyance path 10 in the conveyance direction. Further, when the delivery amount from the agitation conveyance path 10 to the supply conveyance path 9 does not change, the increased amount of developer stays in the agitation conveyance path 10 and also stays in the vicinity of the upstream end in the conveyance direction.
When the developer stays in the vicinity of the upstream end in the transport direction, the surplus opening 92 that delivers the developer from the supply transport path 9 to the stirring transport path 10 is closed by the developer on the stirring transport path 10 side. When the excess opening 92 is blocked by the developer, the developer cannot be moved from the supply conveyance path 9 to the stirring conveyance path 10, but the developer is continuously conveyed by the supply screw 8, so that the conveyance of the supply conveyance path 9 is performed. The developer stays in the vicinity of the downstream end in the direction, and its bulk increases. When the volume of the developer near the downstream end in the conveyance direction of the supply conveyance path 9 rises to the height of the developer discharge port 94, the developer P is discharged to the discharge conveyance path 2 and developed through the discharge conveyance path 2. It is discharged outside the device 4.
In this configuration, when the developer in the agitation transport path 10 is full, the excess developer that has been transported to the most downstream side in the transport direction of the supply transport path 9 without being used for development is supplied and transported to the agitation transport path 10. By setting the surplus opening 92 to overflow with the developer, the movement of the developer from the supply conveyance path 9 to the agitation conveyance path 10 can be restricted, and as a result, the developer that has lost its destination is the developer discharge port. Then, the developer can be discharged.
As described above, even if the developer amount in the developing device 4 increases, even if the developer amount supplied per hour from the agitation transport path 10 to the supply transport path 9 does not change much, the supply transport path 9 By disposing the developer discharge port 94 at the downstream end in the transport direction, the developer in the developing device 4 can be replaced.

In addition, when the premix toner is replenished, the amount of the developer supplied to the upstream side of the supply conveyance path 9 in the conveyance direction increases, but the amount of developer from the supply conveyance path 9 to the stirring conveyance path 10 increases. Some configurations have an upper limit on the delivery amount.
In the developing device 4 having such a configuration, when the premix toner is replenished, the conveyance amount of the agitation conveyance path 10 increases as the developer increases , and the developer from the agitation conveyance path 10 to the supply conveyance path 9 is increased. The amount of delivery will also increase. As a result, the amount of developer supplied to the upstream end of the supply conveyance path 9 in the conveyance direction increases, and the amount of developer conveyed in the supply conveyance path 9 also increases. However, since the amount of developer supplied from the supply conveyance path 9 to the developing roller 5 does not change, the amount of developer that reaches the vicinity of the downstream end in the conveyance direction of the supply conveyance path 9 increases per time. When the amount of developer that reaches the vicinity of the downstream end in the conveyance direction of the supply conveyance path 9 per time exceeds the upper limit of the delivery amount of developer from the supply conveyance path 9 to the stirring conveyance path 10 per hour, the supply conveyance The developer stays in the vicinity of the downstream end of the path 9 in the transport direction, and its bulk increases. When the volume of the developer near the downstream end in the conveyance direction of the supply conveyance path 9 rises to the height of the developer discharge port 94, the developer P is discharged to the discharge conveyance path 2 and developed through the discharge conveyance path 2. It is discharged outside the device 4.
As described above, even when the developer amount in the developing device 4 increases, the amount of developer supplied from the agitation transport path 10 to the supply transport path 9 per unit time increases, even in the transport direction of the supply transport path 9. By disposing the developer discharge port 94 at the downstream end, the developer in the developing device 4 can be replaced.

As described above, the developer discharge port 94 is provided in the vicinity of the downstream end of the supply conveyance path 9 where the volume of the developer fluctuates in accordance with the amount of the developer in the developing device 4. The developer inside can be replaced.
Further, when the premix toner is replenished, that is, when the amount of developer in the entire developer transport path increases, the amount of developer supplied to the upstream side in the transport direction of the supply transport path 9 increases accordingly. For example, the developer discharge port 94 can be provided at any position in the developer transport direction in the supply transport path 9. This is because the configuration in which the amount of developer supplied to the upstream side of the supply conveyance path 9 in the conveyance direction increases the bulk of the developer at any position in the developer conveyance direction in the supply conveyance path 9. is there.
However, when the developer discharge port 94 is provided in the middle of the developer supply region width α of the supply conveyance path 9 and the height of the developer conveyed in the supply conveyance path 9 varies, it is partially When the developer at a high volume is discharged at the developer discharge port 94, the developer may be insufficient on the downstream side of the position where the developer discharge port 94 is provided. If the developer is insufficient within the developer supply / conveyance area width α of the supply / conveyance path 9, the supply of the developer to the developing roller 5 is insufficient, and the supply of the developer from the developing roller 5 to the photoreceptor 1 is insufficient. May cause abnormal images such as missing images. On the other hand, by providing the developer discharge port 94 in the vicinity of the downstream end of the supply conveyance path 9, the downstream end of the developer discharge port 94 is outside the supply conveyance region width α. The shortage can be prevented.

[Example 2]
Next, a second example (hereinafter referred to as “Example 2”) including the characteristic portion of the developing device 4 of the embodiment will be described.
10, Ri sectional view der of the developing device 4 of Example 2 shows a case where the amount of developer is small. FIG. 11 is a cross-sectional explanatory view of the developing device 4 of the second embodiment, and shows a case where the amount of developer is large.
Since the second embodiment differs from the first embodiment in the shapes of the outlet opening / closing member 140 and the wall surface 141 and is common in other configurations, only the differences will be described.
The developing device 4 of Example 2 includes a discharge port opening / closing member 140b having a shape shown in FIG. 10 and a wall surface 141b facing the developer discharge port 94. The discharge port opening / closing member 140b is an elastic body fixed to the wall surface 135, and closes the path toward the developer discharge port 94 where the developer flying by the conveying operation of the supply screw 8 comes into contact with the wall surface 141b. By providing the discharge port opening / closing member 140b and the wall surface 141b, the path of the developer flying by the conveying operation of the supply screw 8 toward the developer discharge port 94 can be blocked as in the first embodiment. Therefore, it is possible to prevent the jumped developer from being discharged, and to prevent the developer from being discharged even though the amount of developer in the developing device 4 has not increased. Therefore, the necessary amount of developer in the developing device 4 can be secured, and the developer can be stably supplied to the photoreceptor 1. As a result, the electrostatic latent image on the photoreceptor 1 can be favorably converted into a toner image, an abnormal image such as image omission can be prevented, and good image formation can be performed.
Further, when the amount of developer in the developing device 4 increases and the volume of the developer increases, the discharge opening / closing member 140b is pushed open by the developer as shown in FIG. Can be discharged to the developer discharge port 94.
Further, the wall surface 140b fills the space above the supply screw 8 and forms a narrow upper path 144 toward the developer discharge port, thereby increasing the vertical sensitivity of the agent interface 142 when the amount of developer in the developing device increases. be able to. As a result, even if the developer amount is increased by a small amount, the agent interface 142 is greatly changed, and the developer amount can be accurately controlled.

Example 3
Next, a third example (hereinafter referred to as “Example 3”) including the characteristic portion of the developing device 4 of the embodiment will be described.
12, Ri sectional view der of the developing device 4 of Example 3 shows a case where the amount of developer is small. FIG. 13 is a cross-sectional explanatory view of the developing device 4 of the third embodiment, and shows a case where the amount of developer is large.
Since the third embodiment differs from the first embodiment in the shape of the outlet opening / closing member 140 and is common in other configurations, only the differences will be described.
The developing device 4 of Example 3 includes a discharge port opening / closing member 140c having a shape shown in FIG. 12 , a support member 145 of the discharge port opening / closing member, and a wall surface 141a facing the developer discharge port 94. A spring is used for the support member 145, whereby the discharge port opening / closing member 140c is supported in a vertically movable manner. Outlet closing member 140c is blocking the path developer flies by the conveying operation of the supply screw 8 by being supported in the state of FIG. 12 when the bulk of the developer is low toward the developer discharge port 94. By providing the discharge port opening / closing member 140c and the wall surface 141a, the path of the developer flying by the feeding operation of the supply screw 8 toward the developer discharge port 94 can be blocked as in the first embodiment. Therefore, it is possible to prevent the jumped developer from being discharged, and to prevent the developer from being discharged even though the amount of developer in the developing device 4 has not increased. Therefore, the necessary amount of developer in the developing device 4 can be secured, and the developer can be stably supplied to the photoreceptor 1. As a result, the electrostatic latent image on the photoreceptor 1 can be favorably converted into a toner image, an abnormal image such as image omission can be prevented, and good image formation can be performed.
Further, the amount of developer within the developing device 4 increases, the bulk of the developer increases, the outlet closing member 140c as shown in FIG. 13 is pushed up by the developer, the amount of agent interface 142 rises developer The developer can be discharged to the developer discharge port 94. This makes it possible to exchange efficiently developer to the extent that the amount of the developer is not insufficient.

Example 4
Next, a third example (hereinafter referred to as “Example 4”) including the characteristic portion of the developing device 4 of the embodiment will be described.
14, Ri sectional view der of the developing device 4 of Example 4 shows a case where the amount of developer is small. FIG. 15 is a cross-sectional explanatory view of the developing device 4 of Example 4 and shows a case where the amount of developer is large.
Since the shape of the discharge port opening / closing member 140 is different from the configuration of the first embodiment and the other configurations are common in the fourth embodiment, only the differences will be described.
The developing device 4 of Embodiment 4 includes a discharge port opening / closing member 140d having a shape shown in FIG. 14 and a support member 146 for the discharge port opening / closing member. A rigid body is used for the discharge port opening / closing member 140d and is supported by a freely rotatable shaft of the support member 146, and is movable in the horizontal direction. Further, when the support member 146 is fixed and an elastic body such as Mylar is used as the discharge port opening / closing member 140d, the horizontal mobility can be obtained similarly.
When the volume of the developer is low, the discharge port opening / closing member 140d is supported in the state shown in FIG. 14 so that the developer flying by the feeding operation of the supply screw 8 blocks the path toward the developer discharge port 94. By providing the discharge port opening / closing member 140d and the wall surface 135, the path of the developer flying by the conveying operation of the supply screw 8 toward the developer discharge port 94 can be blocked as in the first embodiment. Therefore, it is possible to prevent the jumped developer from being discharged, and to prevent the developer from being discharged even though the amount of developer in the developing device 4 has not increased. Therefore, the necessary amount of developer in the developing device 4 can be secured, and the developer can be stably supplied to the photoreceptor 1. As a result, the electrostatic latent image on the photoreceptor 1 can be favorably converted into a toner image, an abnormal image such as image omission can be prevented, and good image formation can be performed.
Also, increased amount of developer within the developing device 4, the bulk of the developer increases, the opening and closing member in the horizontal direction of the pressure with the developer than the developer discharge port 94, the higher the developer bulk as shown in FIG. 15 140d is pushed open. As a result, the developer can be discharged to the developer discharge port 94 when the amount of the developer in the developing device 4 exceeds a certain amount. This makes it possible to exchange efficiently developer to the extent that the amount of the developer is not insufficient.

Further, in the one-way circulation developing device 4 including the supply conveyance path 9, the agitation conveyance path 10, and the collection conveyance path 7, the developer that reaches the downstream end in the conveyance direction of the supply conveyance path 9 does not contribute to development. It is an agent. In the one-way circulation developing device 4, it is suitable to discharge the developer increased by the replenishment of the premix toner at the position where the excess developer stays. This is due to the following reason.
Since the collection conveyance path 7 conveys the developer carried on the developing roller 5 and passed through the development region, even if the amount of the developer in the developing device 4 changes, almost no developer is conveyed in the collection conveyance path 7. There is no change, and the developer cannot be discharged due to an increase in the volume of the developer.
As the amount of developer in the developing device 4 increases, the amount of developer to be transported increases and the bulk of the agitation transport path 10 also increases. However, due to the jumping of the developer to be transported or unevenness in the transport amount, the developer is discharged even if the developer amount does not increase, and the required amount of developer cannot be delivered to the supply transport path 9. is there. For this reason, it is not appropriate to discharge the developer due to the increase in the volume of the developer in the stirring conveyance path 10. Further, the configuration of discharging in the middle of the supply conveyance path 9 may increase the volume of the developer even if the amount of the developer in the developing device 4 is not increased, and the downstream side in the conveyance direction from the discharged position. Is not suitable because the developer may be insufficient.
For this reason, the one-way circulating developing device 4 discharges the developer increased by replenishing the premix toner at the position where the developer that reaches the downstream end in the transport direction of the supply transport path 9 stays. Is suitable.

In the developing device 4 of the embodiment, the excessive opening 92 is larger than the developer discharge port 94, but the developer discharge port 94 may be larger than the excessive opening 92.
Further, in the above-described embodiment, FIG. 4 shows a configuration in which the developer discharging means discharges a part of the developer when the volume of the developer near the downstream end in the transport direction of the supply transport path 9 exceeds a predetermined height. The configuration applied to the developing device 4 having the configuration shown has been described. The configuration to which the characterizing portion of the present invention can be applied is not limited to that shown in FIG. 4, but can be similarly applied to the developing device 4 having the configuration shown in FIG.
In the above-described embodiment, the developing device using the two-component developer composed of the carrier and the toner as the developer has been described. The developing device to which the feature of the present invention is applied is not limited to a developing device using a two-component developer. A developing device using a one-component developer can be used as long as the developer is replenished by the developer replenishing unit and the developer discharging unit discharges the increased amount of developer in the developing device. Is applicable.

As described above, according to the embodiment, as in the first, second, third, or fourth embodiment, the developer flying by the transport operation of the supply screw 8 that is the developer transport member closes the path toward the developer discharge port 94. By providing the discharge port opening / closing member 140 as a developer discharge preventing member, the jumped developer is prevented from reaching the developer discharge port 94 and discharged, and the amount of developer in the developing device 4 is increased. Even though the developer is not discharged, the developer can be prevented from being discharged. Therefore, the necessary amount of developer in the developing device 4 can be secured, and the developer can be stably supplied to the latent image carrier.
In addition, the developer is discharged at a position where the developer that reaches the downstream end in the transport direction of the supply transport path 9 of the one-way circulating developing device 4 including the supply transport path 9, the stirring transport path 10, and the recovery transport path 7 is discharged. As a result, the developer increased by the replenishment of the premix toner can be appropriately discharged.
Further, by providing the developing device 4 as the developing means of the copying machine as the image forming apparatus, it is possible to prevent the occurrence of abnormal images such as missing images while extending the life of the developing means by replacing the developer. Image formation can be performed.

1 is a schematic configuration diagram of a copier according to an embodiment. FIG. 2 is a schematic configuration diagram of a developing device and a photoreceptor. FIG. 3 is a perspective cross-sectional view of the developing device for explaining the flow of the developer. FIG. 3 is a schematic diagram of a developer flow in a developing device. Cross-sectional explanatory drawing of a developing device. FIG. 5 is a schematic diagram of a developer flow in a developing device having a shape different from that in FIG. 4. FIG. FIG. 4 is a cross-sectional explanatory diagram when the developer amount is small in the developing device of Embodiment 1. FIG. 4 is a cross-sectional explanatory diagram when the developer amount is large in the developing device of Example 1. Sectional explanatory drawing in case the amount of developer is small in the developing device of Example 2. Sectional explanatory drawing in case the developer amount is large in the developing device of Example 2. FIG. 10 is a cross-sectional explanatory diagram when the developer amount is small in the developing device of Example 3. Sectional explanatory drawing in case the developer amount is large in the developing device of Embodiment 3. Sectional explanatory drawing when the amount of developer is small in the developing device of Example 4. Sectional explanatory drawing when there is much developer amount in the developing device of Example 4. FIG. Sectional explanatory drawing of the conventional image development apparatus provided with the developer discharge port.

Explanation of symbols

1 photoreceptor 2 discharge conveyance path 2a discharge conveying screw 4 developer 5 developing roller 6 recovery screw 7 recovery path 8 supply disk Ryu
9 Feeding path 10 Stirring path 11 Stirring screw 12 Developing doctor 14 Stretching roller 15 Drive roller 16 Secondary transfer backup roller 17 Intermediate transfer unit 18 Process cartridge 20 Image forming unit 21 Optical writing unit 22 Secondary transfer device 23 Tension Roller roller 24 Paper transport belt 25 Fixing device 26 Fixing belt 27 Pressure roller 90 Belt cleaning device 91 Supply opening 92 Surplus opening 93 Recovery opening 94 Developer discharge port 95 Toner supply port 100 Printer unit 110 Intermediate transfer belt 133 1st Partition wall 134 Second partition wall 135 Partition wall (wall surface)
140 Discharge port opening / closing member 141 Wall surface 142 Agent interface 14 3 Support section
1 45, 146 Support member

Claims (4)

The developer is carried on the surface and rotated, and the developer is carried by supplying the toner to the latent image on the surface of the latent image carrier at a position facing the latent image carrier and developing the developer. A developer conveying member,
Replenishing a developer conveying path for conveying the developer while supplying the developer to the developer carrier in a developer supply region for supplying the developer, the developer in the developer conveying path to said developer carrying member Developer replenishing means,
Wherein the developer predetermined height position bulk increases or decreases of the developer in accordance with the conveyance path across the developer amount increase or decrease, provided the developer discharge port for discharging the developer to the outside of the apparatus to the developer transport path In the developing device
Wherein comprising a closed state to close the developer discharge port, an outlet closing member possible changes to the open state to open the developer discharge port,
The discharge port opening / closing member is movable up and down, closes the developer discharge port when it is below, opens the developer discharge port when it is above , and is biased downward, biasing force is small is set than the developing agent pressure before Symbol outlet opening closed part material when the developer is increased,
A partition wall facing the developer discharge port; the discharge port opening / closing member is fixed below the developer discharge port; and an end of the discharge port opening / closing member is provided on a wall surface of the partition wall on the developer discharge port side. A developing device characterized in that the developer surface is covered by the arrival of the part . The developing device according to claim 1,
Having a guide provided perpendicular to the developer surface;
When the developer bulk is low, the outlet opening / closing member covers the developer surface by moving downward along the guide,
A developing device characterized in that, when the developer bulk is high, the developer discharge port is opened by moving the opening / closing member upward along the guide by the developer pressure . The developer is carried on the surface and rotated, and the developer is carried by supplying the toner to the latent image on the surface of the latent image carrier at a position facing the latent image carrier and developing the developer. A developer conveying member,
In the developer supply area for supplying the developer to the developer carrier, a developer conveyance path for conveying the developer while supplying the developer to the developer carrier, and supplying the developer to the developer conveyance path Developer replenishing means,
A developer discharge port for discharging the developer to the outside of the apparatus is provided in the developer conveyance path at a predetermined height at a position where the volume of the developer increases or decreases according to the increase or decrease of the developer amount in the entire developer conveyance path. In the developing device
A discharge port opening / closing member capable of changing between a closed state for closing the developer discharge port and an open state for opening the developer discharge port;
The discharge port opening / closing member is fixed so as to fall toward the outside of the developer discharge port, and when the discharge port opening / closing member falls due to increased developer pressure, the developer discharge port is in an open state,
The discharge port opening and closing member can be opened and closed with the upper portion of the developer discharge port as a fulcrum,
2. A developing device according to claim 1, wherein the developer discharge port is located above a normal developer surface . At least a latent image carrier;
Charging means for charging the surface of the latent image carrier;
A latent image forming means for forming an electrostatic latent image on the latent image carrier;
An image forming apparatus comprising: developing means for developing the electrostatic latent image into a toner image;
The developing device according to claim 1, 2 or 3 is used as the developing means.
An image forming apparatus.

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