JP6308430B2 - Developing device, image forming apparatus, and process cartridge - Google Patents

Description

  The present invention relates to a developing device, an image forming apparatus, and a process cartridge.

  Conventionally, a photosensitive member as a latent image carrier for carrying a latent image, a developing device for forming a toner image by attaching toner to an electrostatic latent image on the photosensitive member, and a transfer paper that has been conveyed on the photosensitive member. There is known an image forming apparatus that includes a transfer device that transfers the toner image and a cleaning device that cleans paper dust, transfer residual toner, and the like adhering to the photoreceptor after transfer.

Patent Documents 1 and 2 describe an image forming apparatus in which collected toner collected by a cleaning device is returned to a developing device and reused.
In the image forming apparatus described in Patent Document 1, the toner removed from the surface of the photoreceptor by the cleaning brush is conveyed to the mesh member. The reusable toner passes through the mesh member, is sent to the recycling conveyance path, and is supplied from the toner supply port of the developing device. On the other hand, paper powder, agglomerated toner, and the like move on the surface of the mesh member without passing through the mesh member, and are sent to and stored in a waste toner bottle as a toner container.

  The image forming apparatus described in Patent Document 2 is a color machine, and the collected toner of each color collected by the cleaning device is temporarily stored in the collected toner storage unit. When the ratio of the K color toner in the collected toner in the collected toner storage unit is equal to or greater than the specified value, the collected toner in the collected toner storage unit is conveyed to the K color developing device via the recycle conveyance path, and the K color development is performed. The collected toner is supplied from the toner supply port of the apparatus. When the collected toner in the collected toner storage unit becomes full, the collected toner in the collected toner storage unit is conveyed to a waste toner bottle as a toner storage unit via an excessive toner conveyance path.

  The waste toner bottles described in Patent Document 1 and Patent Document 2 can be attached to and detached from the apparatus main body. When the waste toner in the waste toner bottle becomes full, the waste toner bottle is taken out from the apparatus main body to be empty waste toner. Replaced with a bottle.

  The developing device is provided with an opening for allowing the developing roller to face the photosensitive member. When the developing roller installed in the opening rotates, air flows into the developing device from the gap between the developing roller and the opening. This inflow of air increases the internal pressure in the developing device. When the internal pressure in the developing device increases, the pressure increases up to the recycling conveyance path and the waste toner bottle, and increases the internal pressure of the recycling conveyance path and the waste toner bottle. When the internal pressure of the recycling transport path and the waste toner bottle rises, air flows from the joint between the recycling transport path and the toner replenishing port, the joint between the waste toner bottle opening and the transport path for transporting the collected toner to the waste toner bottle, and the like. Leaks out. At this time, there is a problem that the toner in the waste toner bottle and the toner in the recycling transport path are scattered into the image forming apparatus together with the leaking air, and the inside of the image forming apparatus is contaminated by the toner.

  A similar problem occurs in an apparatus that supplies new toner to a developing device from a toner bottle as a toner container. That is, when the internal pressure in the developing device increases, the pressure increases the internal pressure in the toner supply path and the toner bottle. As a result, there arises a problem that the toner scatters together with the junction between the toner bottle and the toner supply path and the air leaking from the junction between the toner supply path and the toner supply port of the developing device.

  The present invention has been made in view of the above problems, and an object thereof is to provide a developing device, a process cartridge, and an image forming apparatus capable of suppressing toner scattering.

To achieve the above object, a first aspect of the invention, at least a current image containing portion you containing a developer including a toner, by the surface carrying the developer in the developer accommodating portion moves, And a developer carrying member that conveys the developer to a developing region facing the surface of the latent image carrying member, and developing the toner image by attaching the toner to the latent image on the latent image carrying member in the developing region. An apparatus having a replenishment toner conveyance path that is connected to a communication hole provided in a sidewall of the developer accommodating portion and conveys toner replenished from a toner replenishing means to the communication hole ; A magnetic carrier is included, and the developer container includes a conveying screw that stirs and conveys the developer, and a wingless portion is provided in the vicinity of the opening on the inner wall surface side of the communication hole of the conveying screw, and , In the developer container By placing a magnet in the vicinity of the opening of the side wall inner wall surface side of Kirendoriana, it is characterized in that closes the side wall inner wall surface side opening of the communication hole in the developer in the developer container.

  According to the present invention, toner scattering can be suppressed.

1 is a diagram illustrating an outline of an image forming apparatus. (A) is a perspective view of a process cartridge. FIG. 4B is a sectional view of the process cartridge. The perspective view which shows the external appearance of a developing device. The perspective view of the state which removed the upper casing and the developing roller so that the inside of the developer accommodating part of a developing device can be visually recognized. FIG. 3 is a diagram schematically illustrating a developer circulation path in a developing device. FIG. 3 is a perspective view of a toner conveying device. FIG. 3 is a cross-sectional perspective view of the toner conveying device. FIG. 3 is an enlarged perspective view of a main part of the toner conveying device. FIG. 3 is a cross-sectional front view of the toner conveying device. AA sectional drawing of FIG. FIG. The perspective view which shows the back side of a process cartridge. The perspective view explaining a mode that a process cartridge is attached to an apparatus main part. FIG. 6 is a perspective view illustrating toner conveyance of the toner conveyance device. FIG. 4 is a diagram for explaining the conveyance of collected toner to a waste toner bottle. FIG. 6 is a diagram for explaining the conveyance of collected toner to a developing device. FIG. 2 is a block diagram showing a part of an electric circuit of the printer. The flowchart of the opening / closing control of a shutter member. The top view which shows the characteristic part of this embodiment. The perspective view which shows the characteristic part of this embodiment. FIG. 3 is a perspective view showing an embodiment in which a magnet 131 is provided above a toner delivery opening. A table summarizing verification experiments conducted by the applicant.

FIG. 1 is a diagram showing an outline of an image forming apparatus according to an embodiment of the present invention.
An image reading apparatus 200 is attached to the upper part of the apparatus main body 100 of the copying machine as an image forming apparatus.

A process cartridge 1 is provided inside the apparatus main body 100.
FIG. 2A is a perspective view of the process cartridge, and FIG. 2B is a cross-sectional view of the process cartridge.
As shown in FIG. 2B, the process cartridge 1 includes a photosensitive member 10 that is a latent image carrier, a charging device 11 that is disposed around the photosensitive member 10 and that acts on the photosensitive member 10, and a developing device. 12 and a cleaning device 14. The process cartridge 1 is detachably attached to the apparatus main body 100. Since the photosensitive member 10, the charging device 11, the developing device 12, and the cleaning device 14 are unitized as the process cartridge 1, replacement and maintenance work is facilitated. Further, it is possible to maintain the positional accuracy between the members with high accuracy, and to improve the quality of the formed image.

  The charging device 11 serving as a charging unit applies a charging bias to apply a charge to the surface of the photoconductor 10 to uniformly charge the photoconductor 10, and an adhering material such as toner attached to the surface of the charging roller 11a. And a removing roller 11b to be removed.

  The developing device 12 as developing means has a first agent storage chamber V1 in which a first conveying screw 12b as developer conveying means is disposed. Further, it also has a second agent storage chamber V2 in which a second conveying screw 12c as a developer conveying means, a developing roller 12a as a developer carrying member, a doctor blade 12d as a developer regulating member, and the like are disposed. .

  In these two agent storage chambers V1 and V2, a developer which is a two-component developer including a magnetic carrier and a negatively chargeable toner is included. The first transport screw 12b is rotationally driven by a driving unit (not shown) to transport the developer in the first agent storage chamber V1 to the front side in the drawing. Then, the developer transported to the front side end portion of the first agent storage chamber V1 in the drawing by the first transport screw 12b enters the second agent storage chamber V2.

  The second transport screw 12c in the second agent storage chamber V2 is rotationally driven by a driving unit (not shown) to transport the developer to the back side in the drawing. In this manner, the developing roller 12a is disposed in a posture parallel to the second conveying screw 12c above the second conveying screw 12c that conveys the developer. The developing roller 12a includes a magnet roller fixedly disposed in a developing sleeve made of a non-magnetic sleeve that is rotationally driven.

  Part of the developer conveyed by the second conveying screw 12c is pumped up to the surface of the developing roller 12a by the magnetic force generated by a magnet roller (not shown) in the developing roller 12a. Then, after the layer thickness is regulated by a doctor blade 12d arranged so as to maintain a predetermined gap from the surface of the developing roller 12a, the layer thickness is regulated and conveyed to a developing region facing the photoconductor 10, and on the photoconductor 10 Toner is attached to the electrostatic latent image. By this adhesion, a toner image is formed on the photoreceptor 10. The developer that has consumed toner by development is returned to the second conveying screw 12c as the surface of the developing roller 12a moves. Then, the developer transported to the end of the second agent storage chamber V2 by the second transport screw 12c returns to the first agent storage chamber V1. In this way, the developer is circulated and conveyed in the developing device.

  Further, the developing device 12 includes a toner concentration sensor 124 (see FIG. 5) that detects the toner concentration of the developer in the first agent storage chamber V1. The toner concentration sensor 124 measures the toner concentration of the developer from the magnetic permeability of the developer. When the toner concentration is lowered, the magnetic carrier is concentrated, so that the magnetic permeability is increased. When the value measured by the toner density sensor 124 exceeds the target value (threshold value), toner is supplied from the toner bottle 20 shown in FIG. 1, and the toner density is controlled to a constant density. The target value is determined based on the detection result obtained by detecting the toner adhesion amount of the toner pattern formed on the photoconductor 10 with an optical sensor (not shown).

  By such an operation, control is performed so that the reference pattern density on the photosensitive member is kept constant. However, when the toner in the toner bottle 20 runs out, the density reduction cannot be suppressed. In such a situation, the detection result of the toner pattern by the optical sensor is not improved despite the operation of supplying the toner from the toner bottle 20 for a predetermined period. Therefore, if the detection result of the toner pattern by the optical sensor is not improved despite the operation of replenishing the toner from the toner bottle 20, it is determined by means (not shown) that the toner has run out (toner end). (Or presumptive judgment).

  In addition, after the toner end is determined, the toner bottle 20 is replaced, and when the toner end recovery for supplying the toner in the replaced toner bottle 20 to the developing device 12 is performed, the following operation is performed. That is, the developing roller 12a and the conveying screws 12b and 12c are rotated in order to satisfactorily mix the replenished toner and the developer. At this time, in order to prevent the developer on the developing roller 12a from sliding unevenly, the photosensitive member 10 is also driven to rotate.

  The cleaning device 14 serving as a cleaning unit includes a cleaning blade 14 a that contacts the surface of the photoconductor 10 and scrapes off transfer residual toner attached to the photoconductor 10. In addition, a toner collection coil 14b is provided that conveys the collected toner collected in the collection unit W and collected by the cleaning blade 14a. The collected toner conveyed by the toner collecting coil 14b is conveyed to the developing device 12 or the waste toner bottle 41 by a toner conveying device 50 described later.

  A transfer device 17 as a transfer unit shown in FIG. 1 includes a transfer roller 16, and the transfer roller 16 is pressed against and brought into contact with the peripheral surface of the photoconductor 10. Further, a thermal fixing device 24 as a fixing unit is provided above the transfer device 17. The thermal fixing device 24 includes a heating roller 25 and a pressure roller 26. Further, the apparatus main body 100 is provided with a laser writing device 21 as latent image forming means. The laser writing device 21 includes a laser light source, a scanning rotary polygon mirror, a polygon motor, an fθ lens, and the like. Further, the apparatus main body is provided with a plurality of sheet cassettes 22 for storing sheets S such as transfer paper and OHP film.

  When copying using the apparatus configured as described above, the user presses a start switch (not shown). Then, first, the contents of the original set on the image reading apparatus 200 are read. At the same time, the photoconductor 10 is rotated by a photoconductor drive motor (not shown), and the surface of the photoconductor 10 is uniformly charged by the charging device 11 using the charging roller 11a. Next, a writing process is executed using the laser writing device 21 by irradiating laser light according to the content of the original read by the image reading device 200. Then, after forming an electrostatic latent image on the surface of the photoconductor 10, toner is attached using the developing device 12 to visualize (develop) the electrostatic latent image.

  At the same time as the user presses the start switch, the selected sheet S is sent out by the calling roller 27 from the multistage sheet cassette 22. Next, the sheet is separated one by one by the supply roller 28 and the separation roller 29 and sent to the supply path R1. The sheet S sent to the supply path R <b> 1 is conveyed by the sheet conveyance roller 30 and is abutted against the registration roller 23 and stopped. The transfer roller 16 is sent to a transfer nip formed in contact with the photoconductor 10 in accordance with the rotation timing of the toner image that is visualized on the photoconductor 10.

  The toner image on the photoreceptor 10 is transferred to the sheet S fed to the transfer nip by the transfer device 17. The residual toner on the photoconductor 10 after the image transfer is removed and cleaned by the cleaning device 14, and the residual potential on the photoconductor 10 from which the residual toner has been removed is removed by a static elimination device (not shown). In preparation for the next image formation starting from the charging device 11.

  On the other hand, the sheet S after the image has been transferred is guided to the heat fixing device 24, passed between the heating roller 25 and the pressure roller 26, and conveyed to these rollers while applying heat and pressure to the toner. The image is fixed. Thereafter, the sheet S on which the image has been fixed is discharged onto the discharge stack unit 32 by the discharge roller 31 and stacked.

Next, the configuration and operation of the developing device 12 will be described in more detail.
FIG. 3 is a perspective view showing the appearance of the developing device 12.
FIG. 4 is a perspective view of a state in which the upper casing and the developing roller 12a are removed so that the inside of the developer accommodating portion of the developing device 12 can be visually recognized.
FIG. 5 is a diagram schematically showing a developer circulation path in the developing device 12. The broken arrow in FIG. 5 indicates the flow of the developer, and the solid arrow in FIG. 5 indicates the flow of the toner replenished from the toner replenishing port 12e.

  A developer accommodating portion is formed inside the developing device 12 by the developing casing 121. The developer accommodating portion has a partition wall 122 that partitions the first agent accommodating chamber V1 and the second agent accommodating chamber V2. Conveying screws 12b and 12c are provided in the first agent storage chamber V1 and the second agent storage chamber V2, respectively. The first agent storage chamber V <b> 1 and the second agent storage chamber V <b> 2 communicate with each other through the transfer openings 121 a and 121 b at the end of the partition wall 122.

  The developer transported to the downstream end of the second agent storage chamber V2 by the transport screw 12c passes through the transfer opening 121a at the end of the partition wall 122 and moves to the first agent storage chamber V1. The developer in the first agent storage chamber V1 is transported in the opposite direction to the developer G in the second agent storage chamber V2 while being stirred by the first transport screw 12b. When the downstream end of the first agent storage chamber V1 in the transport direction is reached, the first agent storage chamber V1 moves to the second agent storage chamber V2 through the transfer opening 121b at the end of the partition wall 122. As described above, the developer circulates in the developer accommodating portion partitioned by the partition wall 122 by the conveying screws 12b and 12c provided in the first agent accommodating chamber V1 and the second agent accommodating chamber V2, respectively. Yes.

  In addition, a replenishment toner transport path 123 is connected to the upstream side of the developer transport upstream of the first agent storage chamber V1. A toner replenishing port 12e is provided in the replenishing toner transport path 123, and new toner and recovered toner collected by the cleaning device 14 are replenished from the toner replenishing port 12e as described later. The first transport screw 12 b provided in the first agent storage chamber V <b> 1 extends to the replenishment toner transport path 123. The toner replenished from the toner replenishing port 12e is conveyed through the replenishment toner conveyance path 123 by the first conveyance screw 12b, and then passes through a communication hole 123a that communicates the first agent storage chamber V1 with the replenishment toner conveyance path 123. It passes through and passes to the 1st agent storage room V1. Further, reference numeral 124 in FIG. 5 denotes a density detection sensor that detects the toner density of the developer, and is installed below the first agent storage chamber V1 of the development casing 121.

Next, the toner recycling mechanism will be described.
FIG. 6 is a perspective view of the toner conveying device 50. FIG. 7 is a cross-sectional perspective view of the toner conveying device 50, and FIG. 8 is an enlarged perspective view of a main part of the toner conveying device 50. 9 is a cross-sectional front view of the toner conveying device 50, and FIG. 10 is a cross-sectional view taken along line AA of FIG.
The toner transport device 50 as toner replenishing means has a recovered toner transport unit 150 that selectively transports the toner collected from the cleaning device 14 to either the developing device 12 or the waste toner bottle 41 (see FIG. 1). doing. The collected toner conveyance unit 150 has a collected toner receiving port 51 that receives the collected toner from the cleaning device 14. The collected toner receiving port 51 is connected to the upstream end of the collected toner conveyance path 55 in the toner moving direction. A collected toner conveyance coil 53 is provided in the collected toner conveyance path 55. A waste toner communication path 56 for dropping the collected toner to the waste toner bottle 41 is connected to the downstream end of the collected toner conveyance path 55 in the toner conveyance direction.

  Further, the collected toner conveyance path 55 is provided with a collected toner supply path 52 for supplying the collected toner to the developing device 12 adjacent to a location where the collected toner receiving port 51 is connected. Further, the collected toner conveyance unit 150 is provided with a shutter member 54 as a path selection unit that opens and closes between the collected toner conveyance path 55 and the collected toner supply path 52. The shutter member 54 is fixed to one end of the drive shaft 54a, and the other end of the drive shaft 54a is connected to the opening / closing motor 54b. By opening and closing the shutter member 54, the collected toner is selectively guided to the path to the waste toner bottle or the path to the developing device.

  Further, as shown in FIGS. 6 and 10, the toner transport device 50 includes a new toner transport path (not shown) for transporting new toner in the toner bottle 20 (see FIG. 1), and a toner supply port of the developing device 12. And a new toner communication path 57 for communicating with 12e.

FIG. 11 is a cross-sectional perspective view of the process cartridge 1.
The transfer residual toner on the photoreceptor 10 is blocked by the cleaning blade 14a and removed from the photoreceptor. The transfer residual toner blocked by the cleaning blade 14a is pushed by the subsequent transfer residual toner and moves upward. Then, it finally moves to the collection unit W and is collected. The collected toner collected in the collecting unit W is conveyed toward the back side end (one axial end) of the process cartridge 1 by the toner collecting coil 14b.

  As shown in FIG. 12, a recovery toner connecting portion 14 c that connects the recovery portion W and the recovery toner receiving port 51 of the toner conveying device 50 is provided on the back side surface of the process cartridge 1. The collected toner transported to the far side end of the process cartridge 1 by the toner collecting coil 14b is transferred to the collected toner connecting portion 14c, and freely falls within the collected toner connecting portion, so that the collected toner receiving port of the toner conveying device 50 can be used. Move to 51.

FIG. 13 is a perspective view for explaining how the process cartridge 1 is mounted on the apparatus main body.
As shown in FIG. 13, the toner conveying device 50 is attached to a side plate (not shown) on the back side of the apparatus main body 100 in the process cartridge mounting direction. When the process cartridge 1 is attached to the apparatus main body 100 as shown in FIG. 13B, the collected toner connecting portion 14c is connected to the collected toner receiving port 51 of the toner conveying device 50 as shown in FIG. Is done. Further, as shown in FIG. 10, the toner replenishing port 12 e of the developing device 12 is connected to the new toner communication path 57 and the collected toner supply path 52 of the toner conveying device 50.

FIG. 14 is a perspective view illustrating toner conveyance of the toner conveyance device 50.
When the value measured by the toner density sensor 124 shown in FIG. 5 exceeds the target value (threshold value), the toner bottle 20 shown in FIG. New toner is conveyed to the new toner communication path 57 as indicated by arrow A2. The new toner conveyed to the new toner communication path 57 falls freely in the new toner communication path 57 and is supplied to the developing device 12 from the toner replenishing port 12e of the developing device 12 as indicated by an arrow A3 in the figure.

  Further, the toner collected by the cleaning device 14 falls freely within the collected toner connecting portion 14c and moves to the collected toner receiving port 51 of the toner conveying device 50 as indicated by an arrow A1 in the drawing. When the collected toner is to be reused, it is supplied to the developing device 12 from the toner supply port 12e of the developing device 12 as indicated by an arrow A3 in the figure. On the other hand, when discarding the collected toner, the collected toner is transported to the waste toner communication path 56, and freely falls in the waste toner communication path 56 as indicated by an arrow A4 in the figure, so that the waste toner bottle 41 (FIG. 9). See).

FIG. 15 is a diagram for explaining the conveyance of the collected toner to the waste toner bottle 41.
FIG. 15A is a cross-sectional perspective view around the collected toner receiving port 51 when the collected toner is conveyed to the waste toner bottle 41. FIG. 15B is a sectional front view when the collected toner is conveyed to the waste toner bottle 41, and FIG. 15C is a sectional view taken along line BB in FIG.
When transporting the collected toner to the waste toner bottle 41, the open / close motor 54b is driven to rotate the drive shaft 54a by a predetermined angle clockwise in FIG. Then, the shutter member 54 fixed to one end of the drive shaft 54a is rotated by a predetermined angle in the clockwise direction of FIG. 15C around the fixed portion with the drive shaft 54a. As a result, as shown in FIGS. 15A and 15C, the shutter member 54 closes the connecting portion between the collected toner conveyance path 55 and the collected toner supply path 52. Therefore, in this case, as shown in FIG. 15B, the collected toner supplied from the collected toner connecting portion 14c to the collected toner receiving port 51 is conveyed through the collected toner conveying path 55 by the collected toner conveying coil 53. Is done. Then, after the collected toner is conveyed to the downstream end of the collected toner conveyance path 55, the collected toner freely falls in the waste toner communication path 56 and moves to the waste toner bottle 41.

FIG. 16 is a diagram illustrating the conveyance of the collected toner to the developing device 12.
FIG. 16A is a cross-sectional perspective view around the collected toner receiving port 51 when the collected toner is conveyed to the developing device 12. FIG. 16B is a cross-sectional front view when the collected toner is conveyed to the developing device 12, and FIG. 16C is a cross-sectional view taken along the line CC in FIG.
When the collected toner is conveyed to the developing device 12, the opening / closing motor 54b is driven in the opposite direction to that when the shutter member 54 is closed, and the drive shaft 54a is rotated counterclockwise by a predetermined angle in FIG. . Then, the shutter member 54 fixed to one end of the drive shaft 54a rotates by a predetermined angle in the counterclockwise direction of FIG. 16C around the fixed portion with the drive shaft 54a. As a result, as shown in FIGS. 16A and 16C, the shutter member 54 is retracted from the communication portion between the collected toner conveyance path 55 and the collected toner supply path 52, and the collected toner conveyance path 55 and the collected toner are collected. Communication with the toner supply path 52 is established. Thus, the collected toner supplied from the collected toner connecting portion 14 c to the collected toner receiving port 51 falls to the collected toner supply path 52 on the way to the waste toner communication path 56 by the collected toner conveying coil 53. Then, the toner is supplied from the toner supply port 12e of the developing device to the developing device 12.

  FIG. 17 is a block diagram showing a part of the electric circuit of the printer. In the figure, a control unit 60 as control means has a CPU (Central Processing Unit) as calculation means. In addition, it has storage means such as RAM (Random Access Memory) and ROM (Read Only Memory). Although various devices and sensors are connected to the control unit 60 that controls the entire apparatus, only the main devices used for the supply control of the collected toner are shown in FIG.

  The control unit 60 controls each means based on a control program stored in the RAM or ROM. Then, the image area ratio is calculated based on the image data. The control unit 60 controls the opening and closing of the shutter member 54 based on the calculated image area ratio.

FIG. 18 is a flowchart of opening / closing control of the shutter member.
As shown in FIG. 18, the control unit 60 counts the cumulative print area of the output image and the travel distance of the developing device (developing roller), and when a certain number of pages is output (Yes in S1). ), The image area ratio per unit distance is calculated from the cumulative image printing area and the travel distance of the developing roller. It is checked whether the image area ratio per unit distance is equal to or greater than a threshold value (S2). In the present embodiment, the threshold is set to 3%.

  The “predetermined number of pages” refers to the number of pages required for the toner removed by the cleaning blade 14a to reach the position where the collected toner conveyance path 55 branches to the path to the waste toner bottle and the path to the developing device. It is. That is, when an image forming operation for a predetermined number of pages is performed, the collected toner removed by the cleaning blade at the time of printing the first sheet reaches the branch. In the image forming apparatus according to the present embodiment, as illustrated in FIG. 2, the collection unit W is located above the contact portion between the cleaning blade 14 a and the photoconductor 10. Therefore, as described above, the transfer residual toner cleaned by the cleaning blade does not immediately go to the collection unit W but continues to be dammed by the cleaning blade. Then, the toner is pushed by the subsequent transfer residual toner, gradually moves upward, and is collected by the collecting unit W. For this reason, “a certain number of pages” is required until the collected toner reaches the position where the collected toner conveyance path 55 branches into the path to the waste toner bottle and the path to the developing device.

The smaller the image area ratio, the larger the contact area between the photoconductor 10 and the transfer paper S and the higher the possibility that paper dust or the like will adhere to the photoconductor 10. Therefore, when the image area ratio per unit distance is less than the threshold (No in S2), it can be determined that a large amount of paper dust is mixed in the collected toner. Therefore, at this time, the shutter member 54 is closed, and the collected toner is transported to the waste toner bottle 41 and discarded (S4). As a result, it is expected that the collected toner collected by the printing operation of “a certain number of pages” has a large amount of paper dust, and is transported to the waste toner bottle 41 and discarded.
On the other hand, when the image area ratio per unit distance is equal to or greater than the threshold value (Yes in S2), it can be determined that the collected toner collected by the printing operation of “a certain number of pages” contains little paper dust. Accordingly, at this time, the shutter member 54 is opened and the collected toner is supplied to the developing device 12 (S3).

  In the above description, the opening / closing of the shutter member 54 is controlled based on the image area ratio per unit distance. However, this is merely an example. For example, the opening / closing of the shutter member 54 is performed based on the image area ratio per page. You may control. Specifically, when a predetermined number of pages is output, an image area ratio per page is calculated from the cumulative print area of the image and the number of pages, and the shutter is based on the image area ratio per page. The opening and closing of the member 54 is controlled. The image area ratio per page can be conveyed to the waste toner bottle 41 when the collected toner contains a large amount of paper dust, and can be conveyed to the developing device when the collected toner contains a small amount of paper dust. .

Next, features of the present embodiment will be described.
As the developing roller 12a rotates, an airflow flows into the developing device. This airflow increases the internal pressure in the apparatus. When the internal pressure in the apparatus increases, the pressure increases the pressure in the collected toner conveyance path 55 and the new toner communication path 57 of the toner conveyance device 50 via the communication hole 123a and the replenishment toner conveyance path 123. Further, the internal pressure of the waste toner bottle 41 and the toner bottle 20 is increased through the collected toner conveyance path 55 and the new toner communication path 57. When the internal pressure of the collected toner conveyance path 55 and the internal pressure of the waste toner bottle 41 increase, air leaks from the joint portion with the toner conveyance device 50. Specifically, the junction between the toner replenishing port 12e and the collected toner supply path 52, the junction between the waste toner bottle 41 and the waste toner communication path 56, and the junction between the collected toner receiving port 51 and the collected toner connecting portion 14c. It is. Further, a junction between the toner supply port 12e and the new toner communication path 57, and a junction between the new toner communication path 57 and a new toner conveyance path (not shown).
When air leaks from these joints, the toner in the toner transport device 50 and the waste toner bottle scatters to the outside of the toner transport device 50 together with the leaked air, causing the inside of the image forming apparatus to become dirty. .

  Therefore, in this embodiment, the developer in the developer accommodating portion closes the opening of the communication hole 123a on the first developer accommodating chamber side so that the internal pressure of the developing device 12 does not reach the toner conveying device 50. did. Below, the characteristic part of this embodiment is demonstrated concretely.

FIG. 19 is a plan view showing the characteristic part of the present embodiment, and FIG. 20 is a perspective view showing the characteristic part of the present embodiment.
As shown in FIGS. 19 and 20, the bladeless portion 130 is provided as a staying means on the replenishing toner conveyance path 123 side of the first conveyance screw 12b disposed in the first agent storage chamber V1 at a location facing the delivery opening 121a. Was provided. As a result, the developer transferred to the bladeless portion 130 out of the developer transferred from the second agent storage chamber V2 to the first agent storage chamber V1 via the transfer opening 121a is transferred to the first transport screw. By 12b, it stays in place without being conveyed. Thereby, the opening of the communication hole 123a of the first agent storage chamber V1 can be filled with the staying developer, and the opening of the communication hole 123a can be closed with the developer. As a result, the internal pressure of the developing device 12 can be suppressed from reaching the toner conveying device 50 via the replenishing toner conveying path 123. Therefore, it is possible to suppress the leakage of air from each of the joints, and it is possible to suppress the scattering of the toner together with the leaking air. As a result, the inside of the image forming apparatus can be prevented from being stained with toner.

Next, verification experiments conducted by the applicant will be described.
First, the number of rotations of the conveying screws 12b and 12c was set to 210 rpm, a plurality of first conveying screws 12b having different bladeless lengths were prepared, and the internal pressure of the toner replenishing port 12e was observed with a slight differential pressure gauge. As a result, when the width of the delivery opening 121a is a and the length of the bladeless portion is b, and D = (a / b) × 100 = 45% or more, the value of the differential pressure gauge becomes negative and the toner supply port 12e became negative pressure.

  Further, the applicant conducted a verification experiment by increasing the rotation speed of each of the conveying screws 12b and 12c (718 rpm). As the rotation speed of the conveying screw was increased, the vicinity of the communication hole 123a of the first agent storage chamber V1 was increased. It becomes difficult for the developer to stay in the tank. As a result, when D = 45%, the communication hole 123a could not be closed with the developer, and the toner replenishing port 12e tended not to have negative pressure. Therefore, the present applicant conducted an experiment by changing to the first conveying screw (D = 67.6% or more) in which the length of the bladeless portion 130 is long, and the internal pressure at the toner replenishing port 12e is again made negative. I was able to. In this way, by increasing the length of the wingless portion 130, the skirt of the mountain formed by the staying developer spreads, and the developer can be retained to a height that closes the opening of the communication hole 123a. Conceivable. However, when the experiment was performed with the length of the wingless portion 130 of the first conveying screw (D = 90.10%), an abnormal image was generated. As a result of making the length of the bladeless portion 130 of the first conveying screw too long, a large amount of developer stays, the amount of developer that is circulated and transported decreases, and a sufficient amount of developer adheres to the developing roller 12a. This is thought to be due to the fact that it was no longer possible. Thus, the longer the length of the wingless portion 130 of the first conveying screw, the more developer that stays and the higher the risk of abnormal images. Therefore, in the developing device in which the rotation number of the conveying screws 12b and 12c is high, as shown in FIG. 21, a magnet 131 as a second developer retaining means is provided above the communication hole 123a on the inner wall of the developer accommodating portion. Is preferred.

  Due to the magnetic force of the magnet 131 above the communication hole 123a, the developer can form a magnetic spike on the communication hole 123a, and the upper half of the opening of the communication hole 123a can be filled with a curtain of magnetic spikes. As a result, the vicinity of the toner replenishing port 12e could be set to a negative pressure at a rotation speed of 718 rpm of each of the conveying screws 12b and 12c and D = 45%.

  By using the magnet 131, the developer staying in the vicinity of the opening surface of the communication hole 123a can be collected by the magnetic force of the magnet, and compared with the case where the length of the bladeless portion 130 is increased, the opening portion of the communication hole 123a. Less developer is required to block the toner. As a result, a decrease in the amount of developer circulated and conveyed can be suppressed, and a sufficient amount of developer can be adhered to the developing roller 12a. Therefore, the latent image on the photoconductor can be developed well, and a good image can be maintained.

FIG. 22 is a table summarizing verification experiments conducted by the present applicant.
“Internal pressure” in FIG. 22 is the internal pressure of the toner replenishing port 12e, and “◯” indicates a negative pressure and “X” indicates a positive pressure. Image defects were judged by outputting all solid (full black) images at 718 rpm and 210 rpm and comparing with all solid images output in the comparative configuration of “featherless part length 0 mm” and “no magnet”. When the degree of image unevenness or image loss was equal to or higher than that of the comparative configuration, it was determined as “◯”, and when the degree of image unevenness or image loss was inferior to the comparative configuration, it was determined as “x”.

  As can be seen from FIG. 22, in the image forming apparatus in which the rotation speed of the conveying screw is 210 rpm and no magnet is provided, the toner replenishing port 12e is set to D = 45% or more and 67.6% or less. Negative pressure can be obtained and a good image can be obtained. Further, in the case of an image forming apparatus in which the rotation speed of the conveying screw is 718 rpm and no magnet is provided, the toner replenishing port 12e can be set to a negative pressure with D = 67.60%, and the occurrence of image defects is suppressed. be able to.

  As can be seen from FIG. 22, in the case of an image forming apparatus in which the rotation speed of the conveying screw is 210 rpm and a magnet is provided, by setting D = 22.5% or more and 67.6% or less, the toner supply port 12e can be set to a negative pressure, and a good image can be obtained. Further, in the image forming apparatus having a rotation speed of the conveying screw of 718 rpm and having a configuration in which a magnet is provided, the toner supply port 12e can be set to a negative pressure by setting D = 45% or more and 67.6% or less, In addition, a good image can be obtained.

  As can be seen from FIG. 22, by providing the magnet 131, the ratio (D%) of the wingless portion to the width of the delivery opening 121a is kept low, and even if there is a small amount of developer staying in the vicinity of the communication hole 123a, The communication hole 123a can be closed by the developer, and the toner supply port 12e can be set to a negative pressure. Thereby, the fall of the developer circulated and conveyed in the developer accommodating portion can be suppressed. Thereby, sufficient developer can be supplied to the developing roller 12a, and a good image can be maintained.

  For this reason, in the apparatus in which the rotation speed of each of the conveying screws 12b and 12c is set to 210 rpm or less, the ratio D% of the bladeless portion is set to 45% to 67.6% without providing a magnet. preferable. This is because the negative pressure of the toner replenishing port 12e can be maintained and the occurrence of image defects can be suppressed with a cheaper configuration than when the magnet 131 is provided. On the other hand, in the apparatus in which the rotation speed of each of the conveying screws 12b and 12c is set to 210 rpm to 718 rpm, the magnet 131 is provided to set the ratio D% of the bladeless portion 130 to 45% to 67.6%. Thereby, the toner replenishing port 12e can be set to a negative pressure, and the occurrence of image defects can be suppressed.

What has been described above is an example, and the present invention has a specific effect for each of the following aspects.
(Aspect 1)
At least a developer containing a developer containing toner, and a developer in the developer containing part are carried and moved to the surface, thereby moving to a developing region facing the surface of the latent image carrier such as the photoreceptor 3. A developing device 12 that includes a developer carrying member such as a developing roller 12a that conveys the developer, and that develops a toner image by attaching toner to a latent image on the latent image carrying member in a developing region. The replenishment toner conveyance path 123 is connected to the communication hole 123a provided in the side wall of the toner and supplied from the toner replenishing means such as the toner conveyance device 50 to the communication hole 123a. The opening on the side is closed with the developer in the developer accommodating portion.
According to (Aspect 1), the air taken in by the rotation of the developer carrying member such as the developing roller 12a is closed by closing the opening on the inner wall surface side of the communication hole with the developer in the developer accommodating portion. Thus, it is possible to suppress the flow to the replenishment toner conveyance path. Therefore, the internal pressure in the developing device can be prevented from reaching the toner replenishing means such as the toner conveying device 50 via the replenishing toner conveying path. As a result, together with air from the joint between the edge of the toner replenishing port 12e of the developing device and the toner replenishing means, the joint between the toner replenishing means and the waste toner bottle 56, and the joint between the toner replenishing means and the toner bottle 20. Toner leakage can be suppressed. As a result, the inside of the image forming apparatus can be suppressed from being contaminated with toner.

(Aspect 2)
In (Aspect 1), the developer is circulated and conveyed in the developer accommodating portion, the developer being circulated is retained, and the retained developer blocks the opening on the inner wall surface side of the communication hole 123a. .
According to (Aspect 2), it is possible to fill the opening on the inner wall surface side of the communication hole 123 with the developer by retaining the circulated and transported developer, and to close the communication hole 123a.

(Aspect 3)
In (Aspect 2), a developer screw 12b that stirs and conveys the developer is provided in the developer accommodating portion, and a wingless portion 130 is provided in the vicinity of the opening on the side wall inner wall surface side of the communication hole 123a of the convey screw 12b.
According to (Aspect 3), the developer present in the wingless portion 1130 of the transport screw stays in place without being transported by the transport screw. Thereby, the developer can be retained in the vicinity of the communication hole of the transport screw 12b, and the opening on the inner wall surface side of the connection hole 123a can be closed.

(Aspect 4)
In (Aspect 3), the developer includes a magnetic carrier, and the magnet 131 is disposed in the vicinity of the opening on the inner wall surface side of the communication hole of the developer accommodating portion.
According to (Aspect 3), as described in the embodiment, the developer can be retained in the vicinity of the opening on the inner wall surface side of the communication hole 123a by the magnetic force of the magnet 131. Thereby, even in a developing device in which the rotation speed of the transport screw is fast, the opening on the inner wall surface side of the communication hole 123a can be closed with the developer. Further, compared with the case where only the bladeless portion is used, the developer closes the opening on the side wall inner wall side of the communication hole 123a with less developer, and the developer closes the opening on the side wall inner wall side of the communication hole 123a with the developer. And a decrease in the amount of developer circulated can be suppressed.

(Aspect 5)
In (Aspect 4), the magnetic flux density of the magnet 131 is 115 mT or more.
According to (Aspect 5), as shown in the verification experiment, the developer retained by the magnetic force of the magnet 131 can satisfactorily close the opening on the inner wall surface side of the communication hole 123a.

(Aspect 6)
In (Aspect 5), the partition wall 122 partitioning the developing container, the transport screws 12b and 12c disposed in the rooms partitioned by the partition wall 122 so that the developer transport directions are different from each other, and the transport screws 12b, 12c is provided with delivery openings 121a and 121b for delivering the developer from one room partitioned by the partition wall 122 to the other room on the downstream side in the developer transport direction, and the communication hole 123a is provided in either one of the rooms. The wingless portion 130 is provided on the side wall at the upstream end of the developer conveying direction of the developer, and is provided so as to face the delivery opening 121a. The length of the developer conveying direction of the wingless portion 130 is set to the delivery opening 121b. The opening width was 22.5% or more.
According to (Aspect 5), as shown in the verification experiment, when the ratio is less than 22.5%, the side wall of the communication hole 123a is configured with the magnet 131 even when the transport screw rotates at a low speed (210 rpm). There is a possibility that the opening on the inner wall surface side cannot be blocked.

(Aspect 7)
In an image forming apparatus including a latent image carrier such as the photosensitive member 10 that carries a latent image, and a developing unit that develops a toner image by attaching toner to the latent image on the latent image carrier, The developing device according to any one of (Aspect 1) to (Aspect 6) is used.
According to (Aspect 7), it is possible to suppress the inside of the image forming apparatus from being stained with toner.

(Aspect 8)
In (Aspect 7), a transfer unit such as a transfer device 17 that transfers a toner image on a latent image carrier such as the photoconductor 10 to a transfer member, and a cleaning that removes deposits attached to the latent image carrier after transfer. And a toner replenishing unit such as a toner conveying device 50 that replenishes the developing device 12 with toner, and the toner replenishing unit conveys the recovered toner removed by the cleaning unit. The recovered toner transport path 55 communicates with the waste toner bottle 41 and communicates with a waste toner transport path for transporting the collected toner to the waste toner bottle 41 and a replenishment toner transport path 123 of the developing device. Branches to a recovered toner supply path for supplying the recovered toner to the developing device, and collects the recovered toner in the recovered toner transport path to the recovered toner transport path and the waste toner transport To one of the road, with a route selection means such as a shutter member 54 for selectively directing.
According to (Aspect 8), as described in the embodiment, when it is determined that a large amount of foreign matter such as paper dust is contained in the toner collected by the cleaning unit such as a cleaning device, the waste toner bottle 41 is discharged. The collected toner can be conveyed. Thereby, it can suppress that paper dust mixes in a developing device. Further, when it is determined that there is little foreign matter such as paper dust in the collected toner, the toner consumption can be suppressed by transporting the collected toner to the developing device and reusing it.
Further, in (Aspect 8), the developing device and the waste toner bottle are configured to communicate with each other via the collected toner conveyance path 55. However, since the communication port 123a is blocked with the developer, the developing device This internal pressure can be prevented from reaching the waste toner bottle 41 via the collected toner conveyance path 55. Thereby, it is possible to prevent the toner in the waste toner bottle from leaking out from the junction between the edge of the opening portion of the waste toner bottle 41 and the collected toner conveyance path 55. Accordingly, it is possible to suppress the toner in the waste toner bottle from being scattered in the image forming apparatus and contaminating the image forming apparatus.

(Aspect 9)
At least the latent image carrier and the developing means in an image forming apparatus comprising a latent image carrier such as the photoreceptor 10 and a developing means such as a developing device 12 for developing the latent image on the latent image carrier as a unit. In the process cartridge configured to be held on a common holder and detachable integrally with the image forming apparatus main body, the developing device of any one of (Aspect 1) to (Aspect 6) is used as the developing means.
According to (Aspect 9), it is possible to provide a process cartridge capable of suppressing the inside of the image forming apparatus from being stained with toner.

1: Process cartridge 10: Photoconductor 12: Developing device 12a: Developing roller 12b: First conveying screw 12c: Second conveying screw 12e: Toner replenishing port 14: Cleaning device 14b: Toner collecting coil 14c: Collected toner connecting portion 17: Transfer device 20: Toner bottle 41: Waste toner bottle 50: Toner transport device 51: Collected toner receiving port 52: Collected toner supply path 53: Collected toner transport coil 54: Shutter member 55: Collected toner transport path 55
56: Waste toner communication path 57: New toner communication path 60: Control unit 121: Development casing 121a, 121b: Developer delivery opening 122: Partition wall 123: Replenishment toner transport path 123a: Communication hole 130: Wingless part 131: Magnet V1: First agent storage chamber V2: Second agent storage chamber W: Recovery unit

JP 2002-162880 A Japanese Patent No. 3944197

Claims (7)

A developer accommodating portion for accommodating a developer containing at least toner;
A developer carrying member that carries the developer in the developer containing portion and moves the surface to move the developer to a developing region facing the surface of the latent image carrying member;
A developing device for developing the toner image by attaching the toner to the latent image of the latent image carrier in the development region;
A replenishment toner conveyance path that is connected to a communication hole provided in a side wall of the developer accommodating portion and conveys the toner replenished from the toner replenishing means to the communication hole;
The developer includes a magnetic carrier;
In the developer accommodating portion, a developer screw for agitating and conveying the developer is provided,
A wingless portion is provided in the vicinity of the opening on the side wall inner wall surface side of the communication hole of the conveying screw, and a magnet is disposed in the vicinity of the opening on the side wall inner wall surface side of the communication hole in the developer container, A developing device characterized in that the opening on the inner wall surface side of the communication hole is closed with the developer in the developer accommodating portion. The developing device according to claim 1,
The developer in the developer container is circulated and conveyed,
A developing device characterized in that the developer being circulated is retained and the opening on the inner wall surface side of the communication hole is closed with the retained developer. The developing device according to claim 1 or 2 ,
The developing device, wherein the magnet has a magnetic flux density of 115 mT or more. The developing device mounting serial to claim 3,
A partition wall for partitioning the developer container;
A transport screw arranged in each room partitioned by the partition wall so that the developer transport directions are different from each other;
A delivery opening for delivering the developer from one chamber partitioned by the partition wall to the other chamber on the downstream side in the developer transport direction of each transport screw;
The communication hole is provided on the side wall at the upstream end in the developer conveyance direction of any one of the chambers, and the wingless part is provided so as to face the delivery opening.
The developing device characterized in that the length in the developer conveying direction of the bladeless portion is 22.5% or more of the opening width of the delivery opening. A latent image carrier for carrying a latent image;
An image forming apparatus comprising: a developing device that develops a toner image by attaching toner to the latent image on the latent image carrier;
As the developing device, an image forming apparatus which comprises using a developing device according to any one of claims 1 to 4. The image forming apparatus according to claim 5 .
Transfer means for transferring the toner image on the latent image carrier to a transfer member;
Cleaning means for removing deposits adhering to the latent image carrier after transfer;
Toner replenishing means for replenishing toner to the developing device;
The toner replenishing means has a collected toner conveyance path for conveying the collected toner removed by the cleaning means,
The collected toner conveyance path communicates with a waste toner bottle, communicates with a waste toner conveyance path for conveying the collected toner to the waste toner bottle, and a replenishment toner conveyance path of the developing device, and collects the collected toner with the developing device. Branch to the recovered toner supply route
An image forming apparatus comprising: a path selection unit that selectively guides the collected toner in the collected toner conveyance path to one of the collected toner supply path and the waste toner conveyance path. In an image forming apparatus comprising a latent image carrier that carries a latent image and a developing unit that develops the latent image on the latent image carrier, at least the latent image carrier and the developing unit are shared as one unit. In a process cartridge configured to be held in a holding body and detachable integrally with the image forming apparatus main body,
As the developing means, the process cartridge, which comprises using a developing device according to any one of claims 1 to 6.

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