JP6440017B2 - Developing device and image forming apparatus - Google Patents

Description

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

  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 stains on the background and toner scattering, etc. 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.

In Patent Documents 1 and 2, a premix developer in which a carrier and a toner are mixed is replenished to the developer in the developing device to restore the toner density, and an increased amount of developer is removed from the developing device. A developing device to be discharged 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, the developing devices of Patent Literature 1 and Patent Literature 2 are provided with a developer discharge port for discharging the developer to the outside of the device in accordance with the increase or decrease in the amount of developer in the device. In these developing devices, 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.

Furthermore, the developing device described in Patent Document 2 is a discharge that can selectively take a closed state in which the developer in the supply conveyance path closes the discharge path toward the developer discharge port and an open state in which the discharge path is opened. A path opening / closing member is provided. In this developing apparatus, in a state where the developer surface is lower than the developer discharge port, the discharge path opening / closing member covers the upper surface of the developer, so that the developer flying by the rotation of the developer conveying screw is discharged to the developer discharge port. Block the path to the. When the developer surface becomes higher than the developer discharge port, the discharge path opening / closing member is opened by being pushed up by the developer. In this state, the developer is discharged through the developer discharge port.
In Patent Document 2, the path toward the developer discharge port is opened and closed depending on the height of the developer surface, thereby preventing the jumped developer from being discharged, and the amount of developer in the developing device is reduced. It is described that it is possible to prevent the developer from being discharged even though it has not increased.

  However, the developing device described in Patent Document 2 has a configuration in which the other end of the discharge path opening / closing member swings around one end of the plate-like discharge path opening / closing member, and the tip end surface of the other end of the discharge path opening / closing member is the developer. It will be in a closed state by contacting or approaching the wall surface below the discharge port. In such a developing device, if the attachment position of one end, which is the swing center of the discharge path opening / closing member, is too close to the developer discharge port side due to an assembly error, the other end abuts against the wall surface in the closed state. Smooth opening / closing operation cannot be performed. In addition, if the attachment position of the one end is too close to the side away from the developer discharge port, a gap through which the developer can pass is created between the other end and the wall surface even in the closed state. The developer cannot be prevented from being discharged. For this reason, it is required to assemble the discharge path opening / closing member with high assembling accuracy.

  The present invention has been made in view of the above problems, and the object thereof is as follows. That is, a developing device capable of lowering the assembly accuracy of the discharge path opening / closing member for suppressing discharge of the developer even though the amount of developer in the device is not increased, and the developing device Is provided.

To achieve the above object, a first aspect of the invention, a developer carrying member for carrying a developer on the surface, the developer in the developer accommodating portion for accommodating a developer to be supplied to said developer carrying member anda developer carrying member for conveying, at a predetermined height of the housing portion forming the wall that forms the developer accommodating portion, provided a developer discharge port for discharging the developer to the outside of the apparatus, the developer containing comprising a closed state to close the discharge path which the developer passes from portion toward the developer discharge port, the discharge passage controlling member that can be taken selectively an open state to open the discharge path, the discharge passage controlling member has one center to the other end is pivotable and in the developing device in an open state by the other end is lifted from the closed state, the other end of the discharge passage controlling member enters the developer discharge opening in a closed condition under the discharge passage controlling member There contacts the lower end portion of the developer discharge opening in the housing section forming wall, a discharge opening opposing member at a position opposed to the developer discharge port across the discharge path, one end of the discharge passage controlling member Is attached to the lower surface of the discharge port facing member to fix one end of the discharge path opening / closing member .

  According to the present invention, the assembly accuracy of the discharge path opening / closing member for suppressing the discharge of the developer even though the amount of the developer in the apparatus is not increased can be made lower than before. effective.

FIG. 3 is a cross-sectional explanatory diagram of the developing device according to the first embodiment in a closed state. 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. 6 is a schematic diagram of a developer flow in a developing device having a shape different from that in FIG. 5. FIG. FIG. 3 is an explanatory cross-sectional view of the developing device according to the first embodiment in an open state. FIG. 2 is a perspective cross-sectional view of the developing device according to the first exemplary embodiment when viewed from an obliquely upper side on the near side in FIG. 1. FIG. 11 is a perspective cross-sectional view of the developing device of Example 1 in a state where a discharge path opening / closing member is removed from the state shown in FIG. 10. FIG. 2 is a perspective cross-sectional view of the developing device according to the first exemplary embodiment when viewed obliquely from the back side in FIG. FIG. 13 is a perspective cross-sectional view of the developing device of Example 1 in a state where the discharge path opening / closing member is removed from the state shown in FIG. 12. FIG. 2 is a perspective cross-sectional view of the developing device according to the first exemplary embodiment when viewed from the diagonally lower side in FIG. FIG. 15 is a perspective cross-sectional view of the developing device of Example 1 in a state where the discharge path opening / closing member is removed from the state shown in FIG. 14. FIG. 3 is an enlarged explanatory view in the vicinity of a downstream end of a supply conveyance path of the developing device of Embodiment 1. FIG. 10 is a cross-sectional explanatory diagram of the developing device according to the second embodiment in a closed state. FIG. 10 is a cross-sectional explanatory diagram of the developing device according to the third embodiment in a closed state. Sectional explanatory drawing of the conventional image development apparatus provided with the developer discharge port. FIG. 6 is an enlarged cross-sectional view in the vicinity of a supply conveyance path for explaining an outline of a developing device described in Patent Document 2;

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 2 is an image forming apparatus to which the present invention can be applied, and is a schematic configuration diagram of a tandem type color laser copying machine (hereinafter referred to as “copying machine 500”) in which a plurality of photoconductors are arranged in parallel. The copier 500 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 four image forming units 20 (Y, M, C, K) for forming images of each color of yellow (Y), magenta (M), cyan (C), and black (K). ing. Y, M, C, and K attached to the numbers of the respective symbols indicate members for yellow, cyan, magenta, and black (the same applies hereinafter). In addition to the image forming unit 20 (Y, M, C, K), an optical writing unit 21, an intermediate transfer unit 17, a secondary transfer device 22, a registration roller pair 49, a belt fixing type fixing device 25, and the like are arranged. It is installed.

  The optical writing unit 21 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like (not shown), and laser light is applied to the surfaces of the four photosensitive members 1 (Y, M, C, K) based on image data. Irradiate.

  The image forming unit 20 (Y, M, C, K) includes a drum-shaped photoreceptor 1 (Y, M, C, K), a charging device and a developing device 4 (Y, M, C, K), a drum cleaning device, a static eliminator, etc. are supported as a unit on a common support. The image forming unit 20 (Y, M, C, K) is supported on a common support as one unit to form a process cartridge, and each of the four process cartridges can be attached to and detached from the copying machine 500 main body. It has become. The copying machine 500 according to the present embodiment has a configuration in which four image forming units 20 (Y, M, C, K), which are process cartridges, are arranged side by side on the printer unit 100. By using the process cartridge, the exchangeability of the image forming unit 20 is improved.

The four image forming units 20 (Y, M, C, and K) have substantially the same configuration except that the colors of the toners handled by the four image forming units 20 (Y, M, C, and K) are different from each other. ”,“ M ”,“ C ”, and“ K ”are appropriately omitted.
The surface of the photoreceptor 1 is uniformly charged by a charger as a charging means. The surface of the photoreceptor 1 subjected to the charging process is irradiated with laser light 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 is formed on the surface of the photoreceptor 1. The formed electrostatic latent image is developed by the developing device 4 as developing means to become a toner image.
The toner image formed on the photoreceptor 1 is primarily transferred to an intermediate transfer belt 110 described later. The surface of the photosensitive member 1 after the primary transfer is cleaned of residual transfer toner by a drum cleaning device.

  In the image forming unit 20, the photoconductor 1 cleaned by the drum cleaning device is discharged by a charge eliminator. Then, it is uniformly charged by the charger and returns to the initial state. The series of processes as described above are similarly executed for the four image forming units 20.

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. Further, it also includes a tension roller 14, a driving roller 15, a secondary transfer backup roller 16, four primary transfer bias rollers 62 (Y, M, C, K), and the like. The intermediate transfer belt 110 is stretched while being tensioned by a plurality of rollers including the stretching roller 14. Then, it moves endlessly in the clockwise direction in FIG. 2 by the rotation of the drive roller 15 driven by a belt drive motor (not shown).

  The four primary transfer bias rollers 62 (Y, M, C, K) are disposed so as to be in contact with the inner peripheral surface side of the intermediate transfer belt 110, respectively, and receive primary transfer bias from a power source (not shown). The four primary transfer bias rollers 62 (Y, M, C, K) press the intermediate transfer belt 110 from the inner peripheral surface side toward the four photosensitive members 1 (Y, M, C, K). Each forms a primary transfer nip. In each primary transfer nip, a primary transfer electric field is formed between the photoreceptor 1 (Y, M, C, K) and the primary transfer bias roller 62 (Y, M, C, K) due to the influence of the primary transfer bias. Is done.

  The above-described Y toner image formed on the yellow photoreceptor 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 1 (M, C, and K) are sequentially superimposed and primarily transferred. By this superimposing primary transfer, a toner image (hereinafter, referred to as a four-color toner image) in which the four-color toner images are superimposed is formed on the intermediate transfer belt 110. The four-color toner image superimposed and transferred on 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 intermediate transfer belt 110 with the driving roller 15 on the left side in FIG.

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 transport belt 24 is stretched by two paper transport stretch rollers 23. The paper transport belt 24 moves endlessly in the counterclockwise direction in FIG. 2 in accordance with the rotational drive of at least one of the paper transport stretch rollers 23. One of the two paper conveyance stretching rollers 23 disposed on the right side in FIG. 2 is intermediately transferred to the secondary transfer backup roller 16 of the intermediate transfer unit 17. The belt 110 and the paper transport belt 24 are sandwiched. 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 paper conveyance stretching roller 23 forming the secondary transfer nip by a power source (not shown). By applying this secondary transfer bias, the four-color toner image on the intermediate transfer belt 110 is transferred from the secondary transfer backup roller 16 side to the paper conveying stretch roller 23 side forming the secondary transfer nip in the secondary transfer nip. Thus, a secondary transfer electric field for electrostatic movement is formed.

  At the secondary transfer nip, the transfer paper fed by a later-described registration roller pair 49 so as to synchronize with the four-color toner image on the intermediate transfer belt 110 is affected by the secondary transfer electric field and the nip pressure. A color toner image is secondarily transferred. As the secondary transfer means, instead of the secondary transfer system in which the secondary transfer bias is applied to the roller member, a system for providing a charger for charging the transfer paper in a non-contact manner may be provided.

  A paper feeding device 200 provided at the lower portion of the copying machine 500 includes a paper bank 43 in which a plurality of paper feeding cassettes 44 are arranged in multiple stages in the vertical direction. In each paper feed cassette 44, a plurality of transfer sheets are accommodated in a stack of sheets. Each paper feed cassette 44 presses the paper feed roller 42 against the uppermost transfer paper in the paper bundle. Then, when the paper feed roller 42 rotates, the uppermost transfer paper is sent out toward the paper feed path 46.

  A plurality of transport roller pairs 47 are arranged in the paper feed path 46 that receives the transfer paper delivered from the paper feed cassette 44, and a pair of registration rollers is provided at the downstream end of the paper feed path 46 in the transport direction of the transfer paper. 49 is provided. In the paper feed path 46, the received transfer paper is conveyed toward the registration roller pair 49 by the conveyance roller pair 47.

  The transfer sheet conveyed toward the registration roller pair 49 is sandwiched between the rollers of the registration roller pair 49 and stops. On the other hand, in the intermediate transfer unit 17, the four-color toner image formed on the intermediate transfer belt 110 enters the above-described secondary transfer nip as the intermediate transfer belt 110 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 on the intermediate transfer belt 110 at the secondary transfer nip. As a result, at the secondary transfer nip, the four-color toner image on the intermediate transfer belt 110 is in close contact with the transfer paper. Then, the four-color toner image in close contact with the transfer paper 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 way exits the secondary transfer nip as the paper transport belt 24 moves endlessly, and is then transferred from the paper transport belt 24 to the fixing device 25.

  The fixing device 25 includes a belt unit that moves endlessly while the fixing belt 26 is 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 between them. Of the two rollers in the belt unit, the roller 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 at the fixing nip.

  The transfer paper subjected to the fixing process in the fixing device 25 reaches the discharge roller 56 and is discharged by the discharge roller 56 onto the stack portion 57 provided outside the left side plate in FIG. Is done. When forming a toner image on the other surface of the transfer paper, the transfer paper after fixing is not conveyed to the discharge roller 56 but returned to the secondary transfer nip described above.

  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 like a book, 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 500, 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 both start traveling, 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 the mirrors provided in the first traveling body 33 and 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 the document reading operation, each device in each image forming unit 20 (Y, M, C, K), the intermediate transfer unit 17, the secondary transfer device 22, and the fixing device 25 start driving. To do. Then, based on the image information constructed by the reading sensor 36, the optical writing unit 21 is driven and controlled, and Y, M, C, K on each photoconductor 1 (Y, M, C, K). Each color toner image is formed. These toner images are transferred onto the intermediate transfer belt 110 in a superimposed manner, thereby forming a four-color toner image.

  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 plurality of paper feeding rollers 42 is selected to start rotational driving, and the transfer paper is sent out from the paper feeding cassette 44 corresponding to the paper feeding roller 42 that has started rotational driving. 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 selected and rotation driving is started and the transfer paper on the manual feed tray 51 is sent out, the manual separation roller 52 separates the transfer paper one by one and manually feeds the printer unit 100. Paper is fed to the paper path 53. The transfer paper fed to the manual paper feed path 53 is conveyed toward the secondary transfer nip.

  When the copier 500 forms a multicolor image composed of toners of two or more colors, the intermediate transfer belt 110 is stretched so that the upper stretched surface is substantially horizontal, and the upper stretched surface is placed on the upper stretched surface. All four photoconductors 1 (Y, M, C, K) are brought into contact. On the other hand, when forming a monochrome image consisting of only K toner, the intermediate transfer belt 110 is tilted so that the left side in FIG. , M, C photoconductors 1 (Y, M, C). Then, among the four photoconductors 1 (Y, M, C, K), only the black photoconductor 1K is rotated counterclockwise in FIG. 2 to form only the K toner image. At this time, for Y, M, and C, the driving of not only the photosensitive member 1 but also the developing device 4 can be stopped, so that unnecessary consumption of the photosensitive member 1 and the developer can be prevented.

  The copier 500 includes a control unit (not shown) configured by a CPU that controls each device in the copier 500, 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 side of the three-sided print mode, which is a mode for forming an image only on one side of the transfer paper, is selected from the three modes. You can choose one. The three single-sided print modes include a direct discharge mode, a reverse discharge mode, and a reverse decal discharge mode.

FIG. 3 is an enlarged configuration diagram showing the developing device 4 and the photoreceptor 1 to which the present invention is provided, which is included in one of the four image forming units 20 (Y, M, C, K). As described above, since the four image forming units 20 (Y, M, C, K) have substantially the same configuration, the subscripts indicating the color of the toner to be used are appropriately omitted in FIG. .
As shown in FIG. 3, 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 charged surface of the photosensitive member 1 by the laser light emitted from the optical writing unit 21, and toner is supplied from the developing device 4 to the electrostatic latent image to form a toner image. The

The developing device 4 has a developing roller 5 as a developer carrying member for supplying and developing toner to the electrostatic latent image on the surface of the photoreceptor 1 while moving in the direction of arrow I in FIG. Further, a supply screw 8 is provided as a supply / conveyance member that conveys the developer in the forward direction of FIG. 3 while supplying the developer to the developing roller 5.
A developing doctor as a developer regulating member that regulates the developer supplied to the developing roller 5 to a thickness suitable for development, on the downstream side of the surface moving direction from the portion facing the supply screw 8 in the vicinity of the surface of the developing roller 5. 12 is provided.
The developed developer that has passed through the developing area is collected on the downstream side of the developing roller 5 in the surface movement direction with respect to the developing area that is the opposite portion between the developing roller 5 and the photoreceptor 1, and the collected collected developer is A recovery screw 6 that is a recovery transport member that transports in the same direction as the supply screw 8 is provided. A supply conveyance path 9 provided with the supply screw 8 is arranged in the lateral direction of the developing roller 5, and a collection conveyance path 7 provided with the collection screw 6 is arranged in parallel 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 as an agitating and conveying member that conveys the developer to the back side in FIG.
The supply conveyance path 9 and the stirring conveyance path 10 are partitioned by a first partition wall 133 as a partition member. The part which partitions the supply conveyance path 9 and the stirring conveyance path 10 of the 1st partition wall 133 into the both ends of the near side and back side in FIG. 3 is an opening part, and the supply conveyance path 9 and the stirring conveyance path 10 Are communicating.

Both the supply conveyance path 9 and the recovery conveyance path 7 are partitioned by the first partition wall 133, but no 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.
Further, the two conveyance paths of the agitation 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 is provided with an opening at the front end portion in FIG. 3, and communicates the agitation transport path 10 and the recovery transport path 7.

  The supply screw 8, the recovery screw 6, and the stirring screw 11, which are developer conveying members, include a rotation shaft and a spiral blade provided on the rotation shaft, and convey the developer in the axial direction by rotating. This is a developer conveying screw. These developer conveying screws are made of resin or metal screws, and each screw diameter is φ22 [mm]. In addition, the screw pitch is set to 50 [mm] for the supply screw, the single winding of 25 [mm] for the collection screw 6 and the stirring screw 11, and the number of rotations is set to about 600 [rpm].

The developer carried on the developing roller 5 is thinned by a developing doctor 12 made of stainless steel, and is transported to a developing area which is a portion facing the photoreceptor 1 and used for development. The surface of the developing roller 5 is V-groove or sandblasted, and is made of Al (aluminum) or SUS (stainless steel) tube having a diameter of 25 [mm]. The gap between the developing doctor 12 and the photoreceptor 1 is 0.3 [mm]. It is about.
The developer after passing through the development region is collected in the collection conveyance path 7 and conveyed to the front side of the cross section in FIG. 3, and stirred at the opening provided at the front end of the first partition wall 133. The developer is transferred to the conveyance path 10. In addition, in the vicinity of the opening of the first partition wall 133 on the upstream side in the developer conveyance direction in the agitation conveyance path 10, the agitation conveyance path from a toner supply port 95 (see FIG. 8 described later) provided on the upper side of the agitation conveyance path 10. 10 is supplied with toner.

Next, the circulation of the developer in the three developer transport paths provided in the developing device 4 will be described.
FIG. 4 is a perspective sectional view of the developing device 4 for explaining the flow of the developer in the developer transport path. Each arrow in FIG. 4 indicates the moving direction of the developer.
5 is a schematic diagram of the flow of the developer in the developing device 4. Like FIG. 4, each arrow in FIG. 5 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. 5).
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 enters the stirring conveyance path 10 from the collection opening 93 of the second partition wall 134. Supplied (arrow F in FIG. 5).
In the agitating and conveying path 10, the supplied excess developer and the collected developer are agitated, conveyed to the downstream side in the conveying direction of the agitating screw 11, and the developer reaching the downstream end in the conveying direction is separated from the first partition wall. It is supplied to the supply conveyance path 9 from the supply opening 91 provided at 133 (arrow D in FIG. 5).

In the agitating and conveying path 10, the agitating screw 11 reverses the collected developer, excess developer, and the toner replenished as necessary in the transfer unit as opposed to the developer conveyed in the collecting and conveying path 7 and the supply conveying path 9. Stir in the direction. 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 based on the sensor output of the toner concentration sensor. Toner is being replenished.

  In the developing device 4 shown in FIG. 5, a supply conveyance path 9 and a recovery 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. For this reason, it is possible to prevent the toner concentration 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. Thereby, since the sufficiently stirred 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 stirred. 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.

Further, as shown in FIG. 5, the movement of the developer from the lower part to the upper part of the developing device 4 is only the arrow D. The movement of the developer indicated by the arrow D is performed by pushing the developer into the downstream end of the agitating and conveying path 10 by the conveying force generated by the rotation of the agitating screw 11, thereby raising the developer and supplying the developer to the supply conveying path 9. To supply.
As described above, when the developer is pushed up and moved when the developer is lifted from the lower side to the upper side, the developer is stressed, which causes a decrease in the life of the developer. Specifically, carrier film scraping or toner spent in the developer occurs at the location, and accordingly, the stability of the image quality cannot be maintained.

  For this reason, 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 in FIG. 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 present embodiment, as shown in FIG. 3, 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. 3. 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. Can flow into a point without going against gravity. Thereby, the stress concerning a developing agent can be reduced.

  Further, a fin member may be provided on the shaft of the agitation screw 11 in a portion where the agitation conveyance path 10 and the supply conveyance path 9 communicate with each other on the downstream side of the developer conveyance path of the agitation conveyance 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, as shown in FIG. 3, the center distance A between the developing roller 5 and the supply transport path 9 is shorter than the center distance B between the developing roller 5 and the stirring transport path 10. The supply conveyance path 9 and the stirring conveyance path 10 are arranged. As a result, the developer can be supplied without difficulty from the supply conveyance path 9 to the developing roller 5, and the apparatus can be downsized.
Further, the stirring screw 11 rotates in the counterclockwise direction (in the direction of arrow C in the figure) as viewed from the front side in FIG. 3, 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 applied to the developer can be further reduced.

FIG. 6 is a cross-sectional explanatory view of the cross section at the rotation center of the supply screw 8 of the developing device 4 as viewed 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. 6, the developing device 4 has a supply opening 91 that is a place where the developer is lifted 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. 7 is a schematic diagram of the developer flow in the developing device 4 having a configuration in which the supply opening 91 and the surplus opening 92 are provided outside the development region width α, unlike FIG.
In the developing device 4 shown in FIG. 7, since the supply opening 91 is provided outside the development 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 transport path region β. It has become. 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. 5, the supply opening 91 is provided in the developing region width α, and therefore, 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 development 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.
As described above, since the developing device 4 in FIG. 5 is provided with the supply opening 91 and the surplus opening 92 within the developing region width α, the developing device 4 in the upper part of the developing device 4 is compared with 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. 8 is an external perspective view of the developing device 4.
As shown in FIG. 8, in the developing device 4, a toner replenishing port 95 for replenishing toner is provided above the upstream end in the conveying direction of the agitating and conveying path 10 including the agitating screw 11. 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 downstream area γ 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.
The toner replenishing port 95 is not limited to a position above the upstream end of the agitation transport path 10 in the transport direction, and may be provided above the downstream end of the collection transport path 7.

  Further, a toner replenishing port 95 may be provided just above the collection opening 93 which is a place 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. Further, since the developer is likely to be mixed in the collection opening 93 that is a delivery portion, the developer can be efficiently stirred by replenishing at this position.

As described with reference to FIG. 5, the developing device 4 includes 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 within the development region width α. Provided. Further, a surplus opening 92 for delivering the developer from the downstream end in the transport direction of the supply transport path 9 to the upstream end in the transport direction of the stirring transport path 10 is provided in the development region width α. For this reason, compared with the conventional developing device 4, space saving of the upper part of the developing device 4 can be achieved, and space saving of the whole developing device 4 can be achieved.
Furthermore, by providing the toner replenishing port 95 in an empty space by providing the surplus opening 92 within the developing region width α, the developing device 4 can be downsized.

By replenishing toner from above the collection opening 93, which is a developer delivery section from the collection conveyance path 7 to the agitation conveyance path 10, the developer can be efficiently agitated.
Further, by providing the developing device 4 as the developing means of the printer unit 100 of the copying machine 500 as an 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 this embodiment, a developer including toner and a carrier is supplied from a toner supply port 95. Hereinafter, the developer in which the toner to be supplied to the developing device 4 and the carrier are mixed is referred to as “premix toner”.

In the developing device 4, when the developer in the supply conveyance path 9 exceeds a predetermined volume, a part of the developer is discharged to the outside of the developing device 4 and discharged from the developer discharging port 94. A discharge conveyance path 2 provided with a discharge conveyance screw 2a for conveying the developer to the outside of the developing device 4; 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.
In this embodiment, the developer discharge port 94 is provided in the supply conveyance path 9. However, the position where the developer discharge port 94 is provided increases or decreases the volume of the developer according to the increase or decrease in the amount of developer in the entire apparatus. If it is a position to perform, you may provide in the collection conveyance path 7 or the stirring conveyance path 10.

Next, the conventional developing device 4 provided with the developer discharge port 94 will be described.
FIG. 19 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. 3 for the conventional developing device 4 provided with the developer discharge port 94.
The vicinity of the downstream end in the conveyance direction of the supply conveyance path 9 is, for example, a location where the developer is transferred from the supply conveyance path 9 to the stirring conveyance path 10 and the same position in the conveyance direction of the supply conveyance path 9. It is.

  Further, the rotation direction of the supply screw 8 in the supply conveyance path 9 is clockwise (direction of arrow M) as shown in FIG. 4, and the developer is supplied to the developing roller 5 from below. It is rotating. 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. 4, the developer is supplied to the developing roller 5 so as to lift the developer from below the supply conveyance path 9 where the developer is accumulated. It becomes like this. The developer supply performance is more stable when the developer is supplied from the lower side than when the developer is supplied so that the developer is scattered. Therefore, in the developing device 4, the rotation direction of the supply screw 8 is clockwise as shown in FIG. It is set.

  In particular, in the case where the developer supplied to the developing roller 5 is not returned to the supply conveyance path 9 and is collected by the collection conveyance path 7 as in the developing device 4 of the present embodiment, the developer amount 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 the developer moving in the supply conveyance path 9 by applying the conveyance force and the rotating force of the supply screw 8 that is a developer conveyance screw. As shown in FIG. 19, when the developer discharge port 94 is simply provided at a predetermined height of the supply conveyance path 9 that is the developer conveyance path, as shown by an arrow T in FIG. 19. 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 this state where the developer that has jumped off is discharged, the developer may be discharged from the developer discharge port 94 even though the amount of the developer in the developing device 4 is less than an appropriate amount. is there. As a result, 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. 19, the arrow T indicates the path of the jumped developer toward the developer discharge port 94. An arrow T in FIG. 19 schematically shows a path of the jumped developer toward the developer discharge port 94, and a path of the jumped developer toward the developer discharge port 94 is indicated by an arrow T. It is not limited to things.

[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. 1 is an explanatory cross-sectional view of the developing device 4 according to the first embodiment.
As shown in FIG. 1, the developing device 4 of Example 1 includes a block member 3 as a flying developer discharge suppressing member. The block member 3 closes the path (arrow T in FIG. 19) where the developer flying by the supply screw 8 being a developer conveying member rotating to convey the developer is directed to the developer discharge port 94. It is possible to suppress the splashed developer from being discharged.

  Further, in the developing device 4, a discharge path 96 through which developer passes from the supply conveyance path 9 toward the developer discharge port 94 is formed between the block member 3 and the partition wall 135. Thus, when the amount of developer in the developing device 4 increases while suppressing the jumped developer from being discharged, the developer is guided to the developer discharge port 94 by the discharge path 96 and exceeds the required amount. The developer can be discharged from the developer discharge port 94.

Further, the developing device 4 according to the first embodiment includes a discharge path opening / closing member 140 that can selectively take a closed state in which the discharge path 96 is closed and an open state in which the discharge path 96 is opened.
FIG. 1 shows a closed state in which the discharge path opening / closing member 140 closes the discharge path 96. FIG. 9 is a cross-sectional explanatory view of the developing device 4 according to the first embodiment, as in FIG. 1, and shows an open state in which the discharge path opening / closing member 140 opens the discharge path 96.

  FIG. 10 is a perspective cross-sectional view of the developing device 4 according to the first exemplary embodiment as viewed obliquely from the front side in FIG. 1, and the cross-section is a cross-section at a position where the developer discharge port 94 is provided. FIG. 11 is a perspective sectional view of the state where the discharge path opening / closing member 140 is removed from the state shown in FIG.

  12 is a perspective cross-sectional view of the developing device 4 according to the first exemplary embodiment when viewed from the obliquely upper side on the back side in FIG. 1, and the cross-section is a cross-section at a position where the developer discharge port 94 is provided. FIG. 12 shows a developing device 4 shown in FIGS. 10 and 11, a doctor fixing casing 12 a to which the developing doctor 12 of the casings forming the developing device 4 is fixed, the developing roller 5, and the developing doctor 12. It is a perspective sectional view of the state where, was removed. FIG. 13 is a perspective sectional view of the state where the discharge path opening / closing member 140 is removed from the state shown in FIG.

  14 is a perspective cross-sectional view of the developing device 4 according to the first exemplary embodiment when viewed from the obliquely lower side on the back side in FIG. It is a cross section in the upstream (back side in FIG. 1). 14 is a perspective sectional view of the developing device 4 shown in FIGS. 12 and 13 with the supply screw 8 removed. FIG. 15 is a perspective sectional view of the state where the discharge path opening / closing member 140 is removed from the state shown in FIG.

The discharge path opening / closing member 140 is made of a sheet-like elastic material, and is attached to the lower surface of the block member 3 by fixing the upper surface of one end thereof, and the lower wall of the other end side forms a partition wall 135 that forms the lower end of the developer discharge port 94. Touch the edge of the. The other end of the discharge path opening / closing member 140 can swing around one end, and the other end side is lifted from the closed state to the open state.
As shown in FIG. 1, the lower surface of the block member 3 is below the edge of the partition wall 135 that forms the lower end of the developer discharge port 94. For this reason, in the closed state shown in FIG. 1, the discharge path opening / closing member 140 contacts the edge of the partition wall 135 in a state of being bent upward with respect to one end side fixed to the lower surface of the block member 3. At this time, a biasing force acts to press the other end side against the edge of the partition wall 135 by the repulsive force against the dead weight and the bending of the discharge path opening / closing member 140.

  Even if the block member 3 is arranged, the developer jumped below the block member 3 may pass through the discharge path 96 and be discharged from the developer discharge port 94. In the developing device 4 according to the first embodiment, even when the developer jumps below the block member 3, the developer collides with the lower surface of the discharge path opening / closing member 140. At this time, when the force by which the developer pushes up the discharge path opening / closing member 140 is smaller than the urging force, the discharge path opening / closing member 140 is kept closed, and the developer can be prevented from being discharged. On the other hand, when the force by which the developer pushes up the discharge path opening / closing member 140 becomes larger than the biasing force, the other end side (left side in FIG. 1) of the discharge path opening / closing member 140 is pushed up by the developer, as shown in FIG. Open. In the open state, a part of the developer in the supply conveyance path 9 passes through the discharge path 96, reaches the discharge conveyance path 2 from the developer discharge port 94, and is discharged to the outside of the developing device 4.

  The force with which the developer in the supply conveyance path 9 pushes up the discharge path opening / closing member 140 varies depending on the amount of developer in the vicinity of the developer discharge port 94 in the supply conveyance path 9. In a state where the amount of the developer is small, the developer surface does not reach the lower surface of the discharge path opening / closing member 140, and the developer that hits the lower surface of the discharge path opening / closing member 140 is small, the developer moves the discharge path opening / closing member 140. The pushing-up force is small, and the discharge path opening / closing member 140 remains closed.

  On the other hand, when the amount of developer in the developing device 4 increases and the amount of developer in the vicinity of the developer discharge port 94 increases, the volume of the developer increases, and the agent surface reaches the lower surface of the discharge path opening / closing member 140. Further, when the bulk of the developer increases, the developer pushes up the discharge path opening / closing member 140 to be in an open state, and the developer is discharged from the developer discharge port 94.

  In addition, the developer surface is not limited to the case where the developer surface reaches the lower surface of the discharge path opening / closing member 140, but may be in an open state. That is, as the amount of developer near the developer discharge port 94 increases, the amount of developer that jumps and hits the lower surface of the discharge path opening / closing member 140 also increases, and the force by which the developer pushes up the discharge path opening / closing member 140 also increases. Even when the developer surface of the developer does not reach the lower surface of the discharge path opening / closing member 140, the force by which the jumped developer pushes up the lower surface of the discharge path opening / closing member 140 is greater than the biasing force. The other end side of the discharge path opening / closing member 140 is lifted and opened.

In both cases where the developer surface pushes up the discharge path opening / closing member 140 and when the splashed developer pushes up the discharge path opening / closing member 140, the developer discharge port 94 in the supply conveyance path 9. When the amount of developer at the position where is provided is small, the closed state is obtained. Then, the developer amount at this position increases, and the developer pushes up the discharge path opening / closing member 140, so that the developer can be discharged and discharged.
With this configuration, the developer that jumps out and is released to the outside of the apparatus is pressed by the discharge path opening / closing member 140, the developer fluidity and the discharge error due to the jump are reduced, and the amount of developer in the developing device 4 is constant. It is possible to realize a configuration in which the developer is discharged when the value exceeds the value.

  As in the developing device 4, the developer is opened and closed by opening and closing a discharge path 96 toward the developer discharge port 94 in accordance with a change in the developer amount at a position where the developer discharge port 94 is provided in the supply conveyance path 9. It is possible to prevent the developer jumped in a small amount from being discharged. Accordingly, it is possible to prevent the developer from being discharged even though the amount of the 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, as shown in FIG. 1, in the closed state, the other end side of the discharge path opening / closing member 140 enters the developer discharge port 94, and the lower surface of the discharge path opening / closing member 140 is at the lower end portion of the developer discharge port 94 in the partition wall 135. Contact.
Even if the position of one end serving as the swing center of the discharge path opening / closing member 140 is slightly separated from the developer discharge port 94 due to an assembly error, the error is within the range in which the discharge path opening / closing member 140 enters the developer discharge port 94 in the closed state. If so, there is no gap through which the developer can pass in the closed state. In addition, even if the position of the one end approaches the developer discharge port 94 somewhat due to an assembly error, the other end enters the developer discharge port 94 without contacting other members such as the inner wall surface of the discharge conveyance path 2. If the error is within a range that only changes, a smooth opening / closing operation can be performed. Thus, even if an assembly error occurs at the position of one end of the discharge path opening / closing member 140, a gap is prevented from being generated in a closed state and a smooth opening / closing operation is performed within a certain error range. As a result, assembly tolerances can be set widely. Therefore, the assembly accuracy of the discharge path opening / closing member 140 for suppressing the discharge of the developer even though the amount of the developer in the apparatus is not increased can be made lower than before.

  As shown in FIG. 1, the developing device 4 according to the first embodiment has a configuration in which a discharge path opening / closing member 140 is attached to the lower surface of the block member 3. In such a configuration, when the developer presses the discharge path opening / closing member 140 from below, a force acts in a direction to press the discharge path opening / closing member 140 against the lower surface of the block member 3. Thereby, even if the discharge path opening / closing member 140 is pushed up by the developer, it is possible to realize a configuration in which the discharge path opening / closing member 140 is hardly peeled off from the block member 3.

  FIG. 20 is an enlarged cross-sectional view of the vicinity of the supply conveyance path 9 for explaining the outline of the developing device provided with the discharge path opening / closing member 140 described in Patent Document 2. In this developing apparatus, the end on the right side of the discharge path opening / closing member 140 in the figure is fixed to the block member 3, the end on the left side in the figure of the discharge path opening / closing member 140 is a free end, and the free end side is the developer. It is configured to be pushed up. In this developing device, as shown in FIG. 20A, the discharge path opening / closing member 140 is in contact with or close to the wall surface of the partition wall 135 below the developer discharge port 94 in the closed state.

  When an operator attempts to install the discharge path opening / closing member 140 in the casing of the developing device, it is required to set a tolerance of about ± 0.5 [mm]. For this reason, if the length from the fixed end to the free end of the discharge path opening / closing member 140 is short even within the tolerance range, as shown in FIG. A gap is generated between the wall 135 and the wall 135. If a gap is generated, the discharge path opening / closing member 140 may be filled with the developer that has flowed upward from the gap above the discharge path opening / closing member 140.

If the length from the fixed end to the free end of the discharge path opening / closing member 140 is long even within the tolerance range, the discharge path opening / closing member 140 is operated during operation of the developing device as shown in FIG. There is a risk of being caught so that the tip of the lower side is on the lower side. When the state shown in FIG. 20C is reached, the discharge path opening / closing member 140 is hardly lifted, the developer discharge is hindered, and there is a possibility that an excessive developer is contained in the developing device.
On the other hand, the developing device 4 according to the first embodiment is not easily affected by the assembly error of the discharge path opening / closing member 140 with respect to the developing device 4 by disposing the discharge path opening / closing member 140 as shown in FIG.

  In the developing device 4 of the first embodiment, a polyethylene terephthalate sheet material having a thickness of 0.05 [mm] is used as the sheet-like discharge path opening / closing member 140. However, the sheet can be opened and closed by increasing or decreasing the developer. It is not limited to this.

FIG. 16 is an enlarged explanatory view of the vicinity of the downstream end of the supply conveyance path 9 of the developing device 4 according to the first embodiment. 14 to 16, the developing device 4 includes an upstream side wall member 38 on the upstream side in the transport direction of the supply screw 8 with respect to the developer discharge port 94, and the supply screw 8 with respect to the developer discharge port 94. The downstream side wall member 39 is provided on the downstream side in the transport direction. The upstream side wall member 38 includes an upstream side wall surface 38f that is perpendicular to the conveying direction of the supply screw 8 (arrow S in FIG. 16) and whose normal direction is opposite to the arrow S direction. The downstream side wall member 39 includes a downstream side wall surface 39f that is perpendicular to the conveying direction of the supply screw 8 (arrow S in FIG. 16) and whose normal direction is the same as the arrow S direction.
The upstream side wall member 38 and the downstream side wall member 39 are gap shielding members that shield the gap between the upper surface of the discharge path opening / closing member 140 and the ceiling of the supply conveyance path 9 on the upstream side and the downstream side of the discharge path opening / closing member 140. .

  By providing the upstream side wall member 38, the developer T <b> 1 flying in the transport direction of the supply screw 8 from the upstream side in the developer transport direction with respect to the developer discharge port 94 hits the upstream side wall surface 38 f of the upstream side wall member 38. . As a result, among the axial directions of the supply screw 8, the path of the developer T <b> 1 flying in the transport direction toward the upper side of the discharge path opening / closing member 140 can be blocked. Therefore, the developer T1 flying in the transport direction is prevented from reaching above the closed discharge path opening / closing member 140, and the developer is prevented from being discharged from the developer discharge port 94 in the closed state. can do.

  Further, by providing the downstream side wall member 39, the developer T <b> 2 flying in the direction opposite to the conveyance direction of the supply screw 8 from the downstream side in the developer conveyance direction with respect to the developer discharge port 94 is It strikes the downstream side wall surface 39f. As a result, of the axial direction of the supply screw 8, the developer T <b> 2 flying in the direction opposite to the transport direction can block the path toward the upper side of the discharge path opening / closing member 140. Therefore, the developer T2 flying in the direction opposite to the transport direction is prevented from reaching above the closed discharge path opening / closing member 140, and the developer is discharged from the developer discharge port 94 in the closed state. Can be prevented.

  Further, the upstream side wall lower end 38e and the downstream side wall lower end 39e, which are lower ends of the upstream side wall member 38 and the downstream side wall member 39, are positioned below the lower end of the developer discharge port 94 as shown in FIGS. doing. Furthermore, the upstream side wall lower end part 38e and the downstream side wall lower end part 39e are located below the lower surface of the block member 3 to which the discharge path opening / closing member 140 is fixed. By arranging in this way, it is possible to realize a configuration that shields the gap between the upper surface of the discharge path opening / closing member 140 and the ceiling of the supply conveyance path 9 on the upstream side and the downstream side of the discharge path opening / closing member 140.

  Moreover, as shown in FIGS. 14-16, the downstream side wall lower end part 39e is located below the upstream side wall lower end part 38e. As a result, a part of the developer that has passed under the lower end portion 38e of the upstream side wall collides with the upstream side wall surface of the downstream side wall member 39 and moves upward so as to face the lower surface of the discharge path opening / closing member 140. With such a configuration, the action of blocking the developer in the vicinity of the developer discharge port 94 is improved, and the response of discharging the developer when the amount of developer in the developing device 4 is increased is improved.

  Further, as shown in FIGS. 14 and 15, the downstream side wall member 39 has a shape in which the downstream side wall lower end portion 39 e is positioned downward toward the side closer to the partition wall 135. That is, the downstream side wall member 39 has a shape that is longer in the vertical direction toward the side closer to the partition wall 135. Thereby, when the amount of developer in the developing device 4 increases, the developer easily pushes up the discharge path opening / closing member 140.

As described above, in the copier 500, the four image forming units 20 (Y, M, C, and K) have substantially the same configuration except that the colors of the toners handled by the image forming units 20 (Y, M, C, and K) are different. The four developing devices 4 included in the forming unit 20 have substantially the same configuration.
In the copying machine 500, the size of the developing gap, which is the gap between the developing roller 5 and the photosensitive member 1, is varied depending on the color of the toner to be handled, and the discharge path opening / closing member 140 is disposed only in the developing device 4 having a large developing gap. It is good also as a structure. This is due to the following reason.

That is, the smaller the development gap is, the less likely the “halo image” is to be generated, but the smaller the development gap is, the more easily the density unevenness due to the influence of the gap fluctuation caused by the rotation of the developing roller 5 and the photosensitive member 1 becomes conspicuous. There is a trade-off relationship with density unevenness. The “hello image” is an abnormal image in which the dot reproducibility of the halftone image adjacent to the solid image is deteriorated due to the influence of the edge electric field generated at the edge portion of the solid image, and is whitened. In the black toner image, the halo image is more noticeable as an abnormal image than the density unevenness due to the development gap variation, and the toner images of other colors (Y, M, C) are caused by the development gap variation than the halo image. The density unevenness tends to stand out as an abnormal image.
Therefore, in the black image forming unit 20K, in order to give priority to the suppression of the halo image, the development gap is set small, and in the color image forming unit 20 (Y, M, C), to give priority to the suppression of the density unevenness. The development gap is set larger than that for black.

  When the development gap is increased, the gap between the developing roller 5 and the photosensitive member 1 in the development area is filled with the developer, so it is necessary to increase the amount of the developer conveyed to the development area. It is also necessary to increase the doctor gap, which is a gap with the roller 5. When the doctor gap is increased, the amount of developer supplied from the supply conveyance path 9 to the surface of the developing roller 5 and passing through the development region and delivered to the collection conveyance path 7 increases. The amount of the developer decreased while being conveyed from the first portion to the downstream end portion is also increased. Therefore, if the developer conveyance speed in the supply conveyance path 9 of the developing device 4 is the same regardless of the size of the development gap, the developer on the downstream side of the supply conveyance path 9 in the development apparatus 4 having a large development gap. May be insufficient. For this reason, in the developing device 4 with a large developing gap, the rotational speed of the supply screw 8 is increased compared to the developing device 4 with a small developing gap in order to increase the developer conveying speed in the supply conveying path 9.

  Even if the size of the developing gap and the doctor gap of the developing device 4 and the rotation speed of the supply screw 8 are made different depending on the color of the toner to be handled, the other parts such as the casing of the developing device 4 have the same configuration, Can be shared. When the other parts have the same configuration in this way, the amount of developer that jumps in the supply conveyance path 9 is larger in the developing device 4 in which the rotation speed of the supply screw 8 is faster. For this reason, in the black developing device 4K in which the rotation speed of the supply screw 8 is slow, even if the discharge path opening / closing member 140 is not arranged, the required amount of developer in the developing device 4 can be secured, but the rotation speed is high. In the developing device 4, the developer is excessively discharged, and the required amount may not be ensured. In such a case, the discharge path opening / closing member 140 is disposed only in the color developing device 4 (Y, M, C) in which the rotation speed of the supply screw 8 is fast.

By disposing the discharge path opening / closing member 140, even if the developing device 4 (Y, M, C) for color has a high rotational speed of the supply screw 8 and a large amount of developer jumps, the developer in the developing device 4 It is possible to secure the necessary amount of
Further, even if the discharge path opening / closing member 140 is not disposed, if the discharge path opening / closing member 140 is disposed in the black developing device 4K that can secure the necessary amount of developer in the developing device 4, the developer exceeding the necessary amount can be obtained. There is a possibility that the developer is not discharged in spite of the housed state. In this case, an excessive amount of developer is accommodated, and there is a risk that the rotational torque of each developer conveying screw, which is a developer conveying member, increases or the developer leaks out. On the other hand, the configuration in which the discharge path opening / closing member 140 is not disposed only in the black developing device 4K in which the rotation speed of the supply screw 8 is slow prevents the developer from being contained excessively, as described above. The occurrence of defects 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.
FIG. 17 is a cross-sectional explanatory diagram of the developing device 4 according to the second embodiment.
Since the developing device 4 of the second embodiment is common to the first embodiment except for the shape of the block member 3 and the attachment position of the discharge path opening / closing member 140, the description of the common configuration is omitted.
As shown in FIG. 17, in the developing device 4 of Example 2, the discharge path opening / closing member 140 is made of a sheet-like elastic material. The discharge path opening / closing member 140 is fixed by attaching one end side of the same surface as the lower surface at the position of the developer discharge port 94 to the side surface of the block member 3 and fixing the other end side to the lower end of the developer discharge port 94. Is in contact with the edge of the partition wall 135 forming the.

As shown in FIG. 17, the discharge path opening / closing member 140 comes into contact with the edge of the partition wall 135 in a state where the discharge path opening / closing member 140 is bent laterally with respect to one end side fixed to the side surface of the block member 3, and the repulsive force against the bending causes An urging force that presses the other end against the edge of the partition wall 135 acts.
As a result, like the developing device 4 of the first embodiment, when the developer amount at the position where the developer discharge port 94 is provided in the supply conveyance path 9 is small, the closed state is established. Then, the developer amount at this position increases, and the developer pushes up the discharge path opening / closing member 140, so that the developer can be discharged and discharged.
With this configuration, the developer that jumps out and is released to the outside of the apparatus is pressed by the discharge path opening / closing member 140, the developer fluidity and the discharge error due to the jump are reduced, and the amount of developer in the developing device 4 is constant. It is possible to realize a configuration in which the developer is discharged when the value exceeds the value.

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.
FIG. 18 is a cross-sectional explanatory view of the developing device 4 according to the third embodiment.
The developing device 4 of Example 3 is the same as that of Example 1 except for the shape of the block member 3, the attachment position of the discharge path opening / closing member 140, the material of the discharge path opening / closing member 140, and the method of attaching the discharge path opening / closing member 140. Therefore, the description of the common configuration is omitted.

  The discharge path opening / closing member 140 of the third embodiment is made of a plate-like rigid material, and unlike the discharge path opening / closing member 140 of the first and second embodiments, it is difficult to bend. In the third embodiment, one end of the discharge path opening / closing member 140 is pivotally attached and fixed to the side surface of the block member 3 via the hinge part 140a, and the lower surface on the other end side forms a lower end of the developer discharge port 94. Contact the edge of 135.

As shown in FIG. 18, the discharge path opening / closing member 140 is rotatable around a hinge part 140 a disposed on the side surface of the block member 3. An urging force that presses against the portion acts.
As a result, like the developing device 4 of the first embodiment, when the developer amount at the position where the developer discharge port 94 is provided in the supply conveyance path 9 is small, the closed state is established. Then, the developer amount at this position increases, and the developer pushes up the discharge path opening / closing member 140, so that the developer can be discharged and discharged.
With this configuration, the developer that jumps out and is released to the outside of the apparatus is pressed by the discharge path opening / closing member 140, the developer fluidity and the discharge error due to the jump are reduced, and the amount of developer in the developing device 4 is constant. It is possible to realize a configuration in which the developer is discharged when the value exceeds the value.

  The embodiment described above is an example of the best mode of the present invention, and does not limit the scope of the claims of the present application. In the above-described embodiment, the configuration in which the image forming apparatus including the developing device 40 having the configuration of the present invention is a copying machine has been described. However, the present invention can also be applied to other image forming apparatuses such as a facsimile and a printer.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
A developer carrier such as a developing roller 5 carrying the developer on the surface, and a developer carrier such as a supply conveyance path 9, a recovery conveyance path 7 and a stirring conveyance path 10 for accommodating the developer supplied to the developer carrier. supply screw 8 for conveying the portion of the developer has a developer conveying member, such as a recovery screw 6 and agitation screw 11, a predetermined accommodating portion formation walls such as the partition wall 135 to form a current image containing portion At a height, a developer discharge port such as a developer discharge port 94 for discharging the developer to the outside of the apparatus is provided, and a discharge path such as a discharge path 96 through which the developer is directed from the inside of the developer container to the developer discharge port. Equipped with a discharge path opening / closing member such as a discharge path opening / closing member 140 that can selectively take a closed state for closing and an open state for opening the discharge path, and the other end of the discharge path opening / closing member can swing around one end. And the other end is lifted from the closed state In the developing device as a release state, the other end of the discharge passage controlling member in a closed state enters the developer discharge port, the lower surface of the discharge passage controlling member contacts the lower end portion of the developer discharge port in the housing section forming wall.
According to this, as described in the above embodiment, the assembly accuracy of the discharge path opening / closing member for suppressing the discharge of the developer even though the amount of the developer in the apparatus has not increased is conventionally increased. Can be lower. This is due to the following reason.
That is, in a developing device having a conventional discharge path opening / closing member, when the position of one end of the discharge path opening / closing member is separated from the developer discharge port due to an assembly error, the developer is between the other end and the wall surface even in the closed state. This will create a gap that can pass through. On the other hand, in the aspect A, even when an assembly error that causes a gap that allows the developer to pass between the other end and the wall surface occurs in the conventional developing device, the discharge path opening / closing member is closed in the closed state. It is possible to set to maintain the state of entering. If the discharge path opening / closing member enters the developer discharge port, there is no gap through which the developer can pass in the closed state.
Further, in the conventional developing device, when the position of the one end approaches the developer discharge port due to an assembly error, the other end abuts against the wall surface in the closed state, and the discharge path opening / closing member is bent. When the amount of deflection increases, smooth opening / closing operations cannot be performed. On the other hand, in aspect A, the length of the other end side of the discharge path opening / closing member that enters the developer discharge port even when an assembly error that causes the discharge path opening / closing member to bend and the smooth opening / closing operation cannot be performed in the conventional developing device occurs. Is only long and does not hinder smooth opening and closing operations.
As described above, in the aspect A, since an assembling error that is not allowed in the conventional developing device can be allowed, the assembling tolerance can be set widely. Therefore, the assembly accuracy of the discharge path opening / closing member for suppressing the discharge of the developer even though the amount of the developer in the apparatus is not increased can be made lower than before.

(Aspect B)
In the aspect A, the developer discharge port such as the developer discharge port 94 is provided at a position in the developer accommodating portion such as the supply conveyance path 9 where the volume of the developer increases or decreases according to the increase or decrease of the developer amount in the entire apparatus. It has been.
According to this, as described in the above embodiment, it is possible to realize a configuration in which the developer is discharged when the amount of the developer in the developing device such as the developing device 4 exceeds a certain amount.

(Aspect C)
In any of the aspects A and B, the developer is discharged to the upstream side and the downstream side of the discharge path opening / closing member such as the discharge path opening / closing member 140 in the developer transport direction in the developer accommodating portion such as the supply transfer path 9. Gap shielding members such as an upstream side wall member 38 and a downstream side wall member 39 that shield a gap between the upper surface of the path opening / closing member and the ceiling of the developer accommodating portion are provided.
According to this, as described in the above embodiment, the developer flying in the direction parallel to the transport direction can block the route toward the upper side of the discharge route opening / closing member 140. For this reason, the developer flying in a direction parallel to the transport direction is prevented from reaching above the closed discharge path opening / closing member, and the developer is discharged from the developer discharge port in the closed state. This can be prevented.

(Aspect D)
In aspect C, the lower end portion (downstream side wall lower end portion 39e) of the gap shielding member such as the downstream side wall member 39 on the downstream side of the discharge path opening / closing member such as the discharge path opening / closing member 140 in the developer transport direction is the upstream side wall on the upstream side. It is located below the lower end (upstream side wall lower end 38e) of the gap shielding member such as the member 38.
According to this, as described in the above embodiment, the action of blocking the developer in the vicinity of the developer discharge port 94 such as the developer discharge port 94 is improved, and the amount of developer in the developing device is increased. The responsiveness of the developer discharge at the time is improved.

(Aspect E)
In any of the aspects A to D, a discharge port facing member such as the block member 3 is provided at a position facing the developer discharge port such as the developer discharge port 94 with the discharge path such as the discharge path 96 interposed therebetween, and the discharge One end of the discharge path opening / closing member is fixed by sticking the upper surface of one end side of the discharge path opening / closing member such as the path opening / closing member 140 to the lower surface of the discharge port facing member.
According to this, as described in the above embodiment, it is possible to realize a configuration in which when the developer pushes up the discharge path opening / closing member, the discharge path opening / closing member is not easily separated from the discharge port facing member.

(Aspect F)
In any of the aspects A to E, the discharge path opening / closing member such as the discharge path opening / closing member 140 is arranged so as to be in contact with the edge in a bent state in the closed state, and is changed from the closed state to the open state. Increases the amount of deflection.
According to this, as described in the above embodiment, the urging force can be applied so as to be in the closed state, and the discharge path opening / closing member can be maintained in the closed state when the amount of the developer is small.

(Aspect G)
A latent image carrier such as the photosensitive member 1; charging means such as a charging device (not shown) for charging the surface of the latent image carrier; and optical writing for forming an electrostatic latent image on the latent image carrier. In an image forming apparatus such as a copying machine 500 having a latent image forming unit such as the unit 21 and a developing unit that develops an electrostatic latent image, the developing device 4 according to any one of modes A to F is used as the developing unit. Etc. is used.
According to this, as described in the above embodiment, the necessary amount of developer in the developing device can be ensured, and the developer can be stably supplied to the latent image carrier such as the photoreceptor 1. it can. As a result, the electrostatic latent image on the latent image carrier can be favorably converted into a toner image, the occurrence of abnormal images such as missing images can be prevented, and good image formation can be performed.

DESCRIPTION OF SYMBOLS 1 Photoconductor 1K Black photoconductor 1Y Yellow photoconductor 2 Discharge conveyance path 2a Discharge conveyance screw 3 Block member 4 Developing device 4K Black development 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 12 Developing doctor 12a Doctor fixed casing 14 Stretch roller 15 Drive roller 16 Secondary transfer backup roller 17 Intermediate transfer unit 20 Image forming unit 20K Black image forming unit 21 Optical writing unit 22 Secondary transfer device DESCRIPTION OF SYMBOLS 23 Paper conveyance tension roller 24 Paper conveyance belt 25 Fixing device 26 Fixing belt 27 Pressure roller 30 Document stand 32 Contact glass 33 First traveling body 34 Second traveling body 35 Imaging lens 36 Reading sensor 38 Upstream side wall member 38e Upstream side wall Lower end 38f Upstream Wall surface 39 Downstream side wall member 39e Downstream side wall lower end portion 39f Downstream side wall surface 42 Paper feed roller 43 Paper bank 44 Paper feed cassette 45 Separating roller 46 Paper feed path 47 Transport roller pair 49 Registration roller pair 50 Manual paper feed roller 51 Manual feed tray 52 Manual feed Separation roller 53 Manual feed path 56 Discharge roller 57 Stack section 62 Primary transfer bias roller 90 Belt cleaning device 91 Supply opening section 92 Excess opening section 93 Collection opening section 94 Developer discharge port 95 Toner supply port 96 Discharge path 100 Printer section 110 Intermediate transfer belt 133 First partition wall 134 Second partition wall 135 Partition wall 140 Discharge path opening / closing member 140a Hinge portion 200 Paper feeder 300 Scanner 400 Automatic document feeder 500 Copying machine

Japanese Patent No. 5037253 Japanese Patent No. 5277487

Claims (6)

A developer carrying member for carrying the developer on the surface;
Anda developer carrying member for conveying the developer in the developer accommodating portion for accommodating a developer to be supplied to said developer carrying member,
At a predetermined height of the housing portion forming the wall that forms the developer accommodating portion, provided a developer discharge port for discharging the developer to the outside of the apparatus,
Wherein comprising a closed state to close the discharge path which the developer passes from developer housing toward the developer discharge port, the discharge passage controlling member that can be taken selectively an open state to open said discharge path,
In the developing device in which the discharge path opening and closing member is swingable around one end and opened by the other end being lifted from the closed state.
In the closed state enters the other end of the discharge passage controlling member within the developer discharge port, the lower surface of the discharge passage controlling member is in contact with the lower end portion of the developer discharge opening in the housing section forming wall,
A discharge port facing member is provided at a position facing the developer discharge port across the discharge route, and an upper surface on one end side of the discharge route opening / closing member is attached to a lower surface of the discharge port facing member, whereby the discharge route A developing device characterized in that one end of an opening / closing member is fixed . The developing device according to claim 1.
The developer outlet, a developing device, characterized in that provided at a position in said developer accommodating portion bulk of the developer increases or decreases according to the increase or decrease in the amount of developer throughout the device. The developing device according to claim 1 or 2,
The conveyance direction of the developer in the developer containing portion, a gap shielding the on the upstream side of the discharge passage controlling member and the downstream side, to shield the gap between the ceiling and the upper surface of the discharge passage controlling member the developer containing portion A developing device comprising a member. The developing device according to claim 3.
The lower end portion of the downstream side of the gap shielding member of the discharge passage controlling member for carrying direction of the developer, a developing device for being located lower than the lower end portion of the upstream side of the gap shielding member. The developing device according to any one of 請 Motomeko 1 to 4,
The discharge passage controlling member is arranged to contact the lower end portion of the developer discharge opening in a bent state in a closed state, wherein the amount of deflection by the open state from the closed state is increased Development device. A latent image carrier;
A charging means for charging said image bearing member surface,
A latent image forming means for forming an electrostatic latent image on said image bearing member,
In an image forming apparatus having a developing means for developing the electrostatic latent image,
Wherein as a developing unit, an image forming apparatus which comprises using a developing device according to any one of claims 1 to 5.

Images