JP2021124576A - Developing device and image forming apparatus including the same - Google Patents

Abstract

To change the amount of a developer to be discharged from a trickle discharge unit to normalize the amount of a developer in a developer tank, and thereby prevent image unevenness.SOLUTION: A developing device 5 of a trickle development system comprises: a developer tank 51 that has a first developer stirring and conveying chamber 511 and a second developer stirring and conveying chamber 512 and stores a developer D; a stirring and conveying member 50 that conveys, while stirring, the developer D in a predetermined conveyance direction; a developer carrier 53 that carries the developer D; a communication unit 510b that communicates the first developer stirring and conveying chamber 511 and the second developer stirring and conveying chamber 512 with each other on an end side of the developer tank 51; and a trickle discharge unit 200 that is provided in the developer tank 51 and discharges the developer D stored in the developer tank 51 to the outside of the developer tank 51. The developing device comprises a developer retention adjustment unit 500 that adjusts the amount of the developer D retained in the communication unit 510b to change the amount of the developer D discharged from the trickle discharge unit 200.SELECTED DRAWING: Figure 9

Description

The present invention relates to a trickle developing type developing apparatus and an image forming apparatus such as a copying machine, a multifunction device, a printer, and a facsimile apparatus provided with the developing apparatus.

As a developing device, a trickle developing type developing device that replaces a deteriorated carrier with a new carrier when developing an electrostatic latent image on an electrostatic latent image carrier with a two-component developer containing toner and carriers as main components. It has been known for a long time.

In a trickle developing type developing apparatus, a developing agent is housed in a developing tank, and the developing agent is conveyed in a predetermined conveying direction while being agitated by a stirring and conveying member. Further, the developing tank is provided with a replenishing unit for replenishing the developing agent into the developing tank and a trickle discharging unit for discharging the surplus developing agent to the outside of the developing tank.

Japanese Unexamined Patent Publication No. 2012-150316 Japanese Unexamined Patent Publication No. 2008-250290

However, the volume and fluidity of the developer changes due to fluctuations in toner concentration and environmental fluctuations such as temperature and humidity. Due to changes in the volume and fluidity of the developer, the developer may be excessively discharged from the trickle discharge portion to reduce the developer, or the developer may be clogged due to a decrease in the dischargeability of the developer. As a result, the amount of the developer picked up on the developer carrier that supports the developer fluctuates, and image unevenness is likely to occur temporarily.

Patent Document 1 discloses a technique for suppressing fluctuations in the developer in the developing apparatus by means of the shapes of the screw and the discharge path.

Patent Document 2 discloses a technique for adjusting the flow rate of the developer by means of an opening forming portion provided in the stirring chamber of the developing tank.

The present invention suppresses fluctuations in the amount of developer picked up on the developer carrier by changing the amount of developer discharged from the trickle discharge section and optimizing the amount of developer in the developing tank. It is an object of the present invention to provide a developing apparatus capable of suppressing unevenness and an image forming apparatus provided with the developing apparatus.

The developing apparatus of the present invention
A developing tank having a first developer stirring and transporting chamber and a second developing agent stirring and transporting chamber and accommodating the developing agent,
A stirring and transporting member that transports the developer contained in the first developer stirring and transporting chamber and the second developing agent stirring and transporting chamber in a predetermined transport direction while stirring.
A developer carrier that supports a developer that has been stirred and transported by the stirring and transporting member, and a developer carrier.
A communication portion that communicates the first developer stirring and transporting chamber and the second developing agent stirring and transporting chamber on one and the other end sides of the developing tank.
A trickle discharge unit provided in the developing tank and discharging the developer contained in the developing tank to the outside of the developing tank.
It is a trickle development type developing device equipped with
It is characterized by including a developer retention adjusting unit that changes the amount of the developer discharged from the trickle discharge unit by adjusting the retention amount of the developer in the communication unit (first configuration).

According to the above configuration, the developer retention adjusting unit changes the amount of the developer discharged from the trickle discharge unit by adjusting the retention amount of the developer in the communication unit. As a result, the amount of the developer in the developing tank can be optimized, fluctuations in the amount of the developer picked up on the developer carrier can be suppressed, and image unevenness can be suppressed.

In the first configuration above
Equipped with a detector that detects the surrounding environment and / or operating conditions
The developer retention adjusting unit may adjust the retention amount of the developer in the communication unit based on the detection result of the detection unit (second configuration).

According to the above configuration, the developer retention adjusting unit adjusts the retention amount of the developer in the communication unit based on the surrounding environment and / or the operating condition. As a result, the amount of the developer discharged from the trickle discharge unit can be changed in accordance with the change in the volume and fluidity of the developer, and the amount of the developer in the developing tank can be optimized.

In the first or second configuration above
The agitation transfer member includes a first agitation transfer member and a second agitation transfer member each having a spiral agitation transfer section.
The developer retention adjusting unit is
By changing the relative positions of the stirring and transporting portion in the first stirring and transporting member and the second stirring and transporting member, the retention amount of the developer in the communicating portion may be adjusted (third configuration).

According to the above configuration, the retention amount of the developer in the communication portion is adjusted by using the first stirring and transporting member and the second stirring and transporting member provided for stirring and transporting the developer. As a result, the amount of the developer discharged from the trickle discharge unit can be changed and the amount of the developer in the developing tank can be optimized while suppressing the complexity of the configuration.

In the third configuration above
The developer retention adjusting unit is
When the first stirring and transporting member and the second stirring and transporting member are operating, the distance from the stirring and transporting portion of the first stirring and transporting member to the communicating portion in a plan view and the second stirring and transporting member in a plan view. By matching or differentizing the distance from the stirring and transporting section to the communicating section, the relative positions of the stirring and transporting section in the first stirring and transporting member and the second stirring and transporting member may be changed (the first). 4 configuration).

According to the above configuration, the developer retention adjusting unit may match or differ the distances from the stirring and transporting parts of the first stirring and transporting member and the second stirring and transporting member to the communicating parts, thereby matching or different from the first stirring and transporting member. And the relative position of the stirring and transporting portion in the second stirring and transporting member is changed. As a result, the amount of the developer discharged from the trickle discharge unit can be changed and the amount of the developer in the developing tank can be optimized while suppressing the complexity of the configuration.

In the third or fourth configuration above
The developer retention adjusting unit is
It has a clutch for transmitting a driving force for driving the first stirring and transporting member and / or the second stirring and transporting member.
By switching the clutch, the relative phases of the stirring and transporting portion of the first stirring and transporting member and the second stirring and transporting member may be changed (fifth configuration).

According to the above configuration, the developer retention adjusting unit changes the relative phases of the stirring and transporting parts of the first stirring and transporting member and the second stirring and transporting member by switching the clutch. Thereby, the relative positions of the stirring and transporting portions in the first stirring and transporting member and the second stirring and transporting member can be changed without complicating the configurations of the first stirring and transporting member and the second stirring and transporting member.

In the third or fourth configuration above
The developer retention adjusting unit is
The first drive transmission unit into which the driving force for driving the first stirring and transporting member is input, and
A second drive transmission unit to which a driving force for driving the second stirring and transporting member is input, and
Have,
By changing the driving force input to the first drive transmission unit and the second drive transmission unit, the relative phases of the first stirring transfer member and the second stirring transfer member are changed. May be allowed (sixth configuration).

According to the above configuration, the developer retention adjusting unit changes the driving force input to the first drive transmission unit and the second drive transmission unit to perform stirring transfer of the first stirring transfer member and the second stirring transfer member. Change the relative phase of the part. Thereby, the relative positions of the stirring and transporting portions in the first stirring and transporting member and the second stirring and transporting member can be changed without complicating the configuration of the developing apparatus.

In any of the third to sixth configurations,
The first stirring and transporting member and / or the second stirring and transporting member is provided with a paddle extending in a direction intersecting the stirring and transporting portion.
The developer retention adjusting unit is
By changing the relative positions of the stirring and transporting portion and the paddle in the first stirring and transporting member and the second stirring and transporting member, the retention amount of the developer in the communicating portion may be adjusted (seventh configuration). ).

According to the above configuration, the paddle increases the transfer amount of the developer between the first stirring and transporting member and the second stirring and transporting member. Therefore, by changing the relative positions of the stirring and transporting portion and the paddle in the first stirring and transporting member and the second stirring and transporting member, the retention amount of the developer in the communicating portion can be significantly changed. This makes it easier to change the amount of developer discharged from the trickle discharge section.

The image forming apparatus of the present invention
The developing apparatus having the first to seventh configurations is provided (eighth configuration).

According to the above configuration, the developer retention adjusting unit changes the amount of the developer discharged from the trickle discharge unit by adjusting the retention amount of the developer in the communication unit. As a result, the amount of the developer in the developing tank can be optimized, fluctuations in the amount of the developer picked up on the developer carrier can be suppressed, and image unevenness can be suppressed.

According to the present invention, it is possible to suppress fluctuations in the amount of the developer picked up on the developer carrier and suppress image unevenness.

It is a schematic cross-sectional view which shows the image forming apparatus provided with the developing apparatus which concerns on Embodiment 1 of this invention. It is a perspective view which looked at the developing apparatus from diagonally above on the front side. FIG. 5 is a cross-sectional view taken along the line AA of FIG. It is a perspective view which looked at the state which removed the top cover member in a developing apparatus from diagonally above on the front side. It is a schematic plan view which shows typically the flow of the developer housed in a developing tank. It is a block diagram which shows the system structure of the control part in an image forming apparatus. It is a top view which shows typically the rotation angle of the 1st stirring transfer member and the 2nd stirring transfer member, and the transport state of a developer. It is a top view which shows typically the rotation angle of the 1st stirring transfer member and the 2nd stirring transfer member, and the transport state of a developer. It is sectional drawing in BB line of FIG. FIG. 5 is a cross-sectional view taken along the line CC of FIG. It is a schematic plan view which shows typically the flow of the developer accommodated in the developing tank in the developing apparatus which concerns on Embodiment 2 of this invention. It is a schematic plan view which shows typically the flow of the developer accommodated in the developing tank in the developing apparatus which concerns on Embodiment 3 of this invention. It is a top view which shows the 1st stirring transfer member and 2nd stirring transfer member in the developing apparatus which concerns on Embodiment 4 of this invention.

[Embodiment 1]
Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In the following description, the same parts are designated by the same reference numerals. Their names and functions are the same. Therefore, the detailed description of them will not be repeated. In the figure, reference numeral X indicates a width direction, reference numeral Y indicates a front-back direction, and reference numeral Z indicates a vertical direction.

[Image forming device]
FIG. 1 is a schematic cross-sectional view showing an image forming apparatus 100 provided with developing apparatus 5a to 5d according to an embodiment of the present invention. As shown in FIG. 1, the image forming apparatus 100 is an electrophotographic image forming apparatus, and is an intermediate transfer type color multifunction device capable of forming a full-color image. In the image forming apparatus 100, a plurality of electrostatic latent image carriers (specifically, photoconductors 2a to 2d) are arranged side by side in the width direction X. In the present embodiment, the image forming apparatus 100 is a color image forming apparatus, but it may be a monochrome image forming apparatus.

An image reading device 40 is provided on the upper part of the image forming device main body 1. The image reading device 40 reads the document G conveyed by the document conveying unit 42 by the image reading unit 41, or reads the document G placed on the document loading table 43 by the image reading unit 41. The image of the document G read by the image reading device 40 is sent to the image forming apparatus main body 1 as image data, or the image data from an external device is sent to the image forming apparatus main body 1 and formed based on the image data. The image is recorded on the recording material P.

The image forming apparatus 100 includes an image forming unit 30. In the image forming unit 30, charging devices 3a to 3d, developing devices 5a to 5d, and photoconductor cleaning devices 8a to 8d are arranged in this order around the photoconductors 2a to 2d, respectively. The image forming unit 30 forms an image with the toners Ta to Td supplied from the toner cartridges 60a to 60d (toner accommodating unit).

The image forming apparatus 100 includes four sets of image forming stations Pa to Pd, an exposure apparatus 4, a primary transfer apparatus 6a to 6d, an intermediate transfer belt 7 (toner image carrier), a belt cleaning apparatus 9, and a secondary transfer apparatus 11. It includes a fixing device 12, a paper feeding device 13 (recording material accommodating portion), and a main body frame 1a.

At the image forming stations Pa to Pd, the toners Ta to Td are supplied from the toner cartridges 60a to 60d to the developing devices 5a to 5d.

The toner cartridges 60a to 60d include black (B), cyan (C), magenta (M), and yellow (Y) toners Ta to Td, and carriers Ca to a predetermined ratio (for example, 10% by weight to 20% by weight). Cd is housed. The toner cartridges 60a to 60d are attached to the image forming apparatus main body 1 by being inserted into the insertion holes 1aa to 1ad in the image forming apparatus main body 1 toward one side Y1 in the front-rear direction Y. The toner cartridges 60a to 60d are communicated with the developing devices 5a to 5d via the replenishment unit 61 (see FIG. 3) in a state of being mounted on the image forming apparatus main body 1.

The developing devices 5a to 5d develop the electrostatic latent image on the photoconductors 2a to 2d with the two-component developing agents Da to Dd containing the toners Ta to Td and the carriers Ca to Cd as main components. The trickle developing method is adopted in the developing devices 5a to 5d. In the trickle developing method, carriers Ca to Cd are added little by little when the toners Ta to Td are replenished to the developing tanks 51a to 51d (developing housing), while the surplus developing agents Da to Dd are discharged to develop the developing agent. Gradually replace Da to Dd. By doing so, the charge levels of the developing agents Da to Dd can be stabilized. The configurations of the developing devices 5a to 5d will be described in detail later.

The excess developing agents Da to Dd from the developing devices 5a to 5d and the residual toner removed by the photoconductor cleaning devices 8a to 8d are collected in the collection container 90. Further, the residual toner removed by the belt cleaning device 9 is collected in the collection container 90. The collection container 90 is shown by an alternate long and short dash line in FIG. The collection container 90 is detachably provided on the image forming apparatus main body 1.

In the image forming apparatus 100, when the image is formed, the surfaces of the photoconductors 2a to 2d uniformly charged by the charging apparatus 3a to 3d are laser-exposed by the exposure apparatus 4 according to the image data (image information). Electrostatic latent images are formed on the photoconductors 2a to 2d, respectively. The electrostatic latent images formed on the photoconductors 2a to 2d are developed by the developing devices 5a to 5d and visualized in toner images, respectively. The toner images on the photoconductors 2a to 2d are transferred by the primary transfer devices 6a to 6d on the intermediate transfer belt 7 stretched on the driving roller 7a and the driven roller 7b. The toner image on the intermediate transfer belt 7 is conveyed to the secondary transfer device 11 by the intermediate transfer belt 7 rotated in the predetermined rotation direction E.

On the other hand, the recording material P drawn out from the paper feed roller 13a of the paper feed device 13 toward the transfer path S is conveyed to the resist roller 15 by the transfer roller 14 through the transfer path S. The recording material P is conveyed by the resist roller 15 in synchronization with the toner image on the intermediate transfer belt 7. The toner image on the intermediate transfer belt 7 is transferred to the recording material P by the secondary transfer roller 11a of the secondary transfer device 11. The toner image transferred onto the recording material P is heated and pressurized by the fixing roller 12a and the pressure roller 12b of the fixing device 12 and fused onto the recording material P. The fixing-treated recording material P is discharged to the outside of the image forming apparatus main body 1 by the discharge roller 16 and placed on the discharge tray 17.

When the image is formed not only on the front surface of the recording material P but also on the back surface, the fixing-treated recording material P is conveyed in the reverse direction to the reversing path Sr by the reverse rotation of the discharge roller 16. The front and back sides of the recording material P conveyed to the reversing path Sr are inverted and guided to the resist roller 15 again, and a toner image is formed and fixed on the back surface in the same manner as on the front surface. After that, the recording material P is discharged to the outside of the image forming apparatus main body 1 by the discharge roller 16 and placed on the discharge tray 17.

In the following description, the developing devices 5a to 5d, the developing tanks 51a to 51d, the developing agents Da to Dd, the toners Ta to Td, the carriers Ca to Cd, the toner cartridges 60a to 60d, and the photoconductors 2a to 2d are used, respectively. It may be simply referred to as a developing device 5, a developing tank 51, a developing agent D, a toner T, a carrier C, a toner cartridge 60, and a photoconductor 2.

[Developer]
FIG. 2 is a perspective view of the developing device 5 viewed from diagonally above on the front side. FIG. 3 is a cross-sectional view taken along the line AA of FIG. 2 and 3 show a state in which the developing agent D is not contained in the developing tank 51.

As shown in FIGS. 2 and 3, the developing apparatus 5 includes a developing tank 51, a stirring and transporting member 50, a developing roller 53 as a developing agent carrier, a doctor blade 54, and a receiving portion 55.

The developing tank 51 constitutes a developing device main body that supports each component of the developing device 5. The developing tank 51 includes a first developer stirring and transporting chamber 511, a second developing agent stirring and transporting chamber 512, and a partition member 58.

The first developer stirring and transporting chamber 511 and the second developer stirring and transporting chamber 512 extend along the longitudinal direction L. The first developer stirring and transporting chamber 511 and the second developer stirring and transporting chamber 512 accommodate the developer D.

The partition member 58 is provided between the first developer stirring and transporting chamber 511 and the second developer stirring and transporting chamber 512, and forms a transport path for the developer D. The partition member 58 extends along the longitudinal direction L. The partition member 58 is a plate-shaped member erected above the bottom surface of the developing tank 51.

The stirring and transporting member 50 circulates and transports the developer D in the developing tank 51. The stirring and transporting member 50 includes a first stirring and transporting member 56 (first stirring and transporting screw) and a second stirring and transporting member 57 (second stirring and transporting screw). The first stirring and transporting member 56 is provided in the first developing agent stirring and transporting chamber 511. The second stirring and transporting member 57 is provided in the second developing agent stirring and transporting chamber 512. The toner T and the carrier C contained in the developing agent D are mixed, stirred, and charged in the developing tank 51.

The developing roller 53 carries the developer D housed in the developing tank 51. The developing roller 53 is provided on the side of the first developer stirring and transporting chamber 511. The developing roller 53 has a magnet roller 531 and a developing sleeve 532.

The developing roller 53 attracts the carrier C in the developing agent D in the developing tank 51 to the developing sleeve 532 in the developing roller 53 by the magnetic force of the magnet roller 531. As a result, the developing roller 53 can form spikes (magnetic brush) of the developing agent D.

The developing sleeve 532 rotates in the second rotation direction R2 opposite to the first rotation direction R1 of the photoconductor 2 by the rotational driving force from the image forming apparatus main body 1. As a result, the developing roller 53 can supply the developing agent D to the photoconductor 2.

The tip of the doctor blade 54 is arranged so as to have a predetermined distance from the developing sleeve 532. The doctor blade 54 regulates the height of the spikes of the magnetic brush to regulate the layer thickness of the developer D.

The receiving unit 55 (see FIG. 2) receives the toner T and the carrier C from the toner cartridge 60. The receiving unit 55 has a supply port 551. The supply port 551 communicates with the supply port of the supply unit 61 in a state where the developing device 5 is attached to the image forming apparatus main body 1. The replenishment unit 61 replenishes the toner T including the carrier C from the toner cartridge 60 from the supply port 551 to the developing tank 51.

FIG. 4 is a perspective view of the developing device 5 with the top cover member 52 removed, as viewed from diagonally above the front side. FIG. 4 shows a state in which the developing agent D is not contained in the developing tank 51.

As shown in FIG. 4, the first stirring and transporting member 56 and the second stirring and transporting member 57 are bearings (not shown) on both side walls 513 and 514 of one side Y1 and the other side Y2 in the front-rear direction Y of the developing tank 51. Each is rotatably supported via. The first stirring and transporting member 56 conveys the developer D in a predetermined first transporting direction W1 (conveying direction W) while stirring. The second stirring transfer member 57 (second stirring transfer screw) conveys the developer D in the second transfer direction W2 (L2 direction) opposite to the first transfer direction W1 while stirring.

The first stirring and transporting member 56 is arranged below the developing roller 53 in the first developing agent stirring and transporting chamber 511. The first stirring and transporting member 56 has a rotating shaft 561 and a spiral stirring and transporting unit 562. The rotating shaft 561 is rotatably supported by both side walls 513 and 514. The stirring and transporting unit 562 is provided on the rotating shaft 561 and is configured to transport the developer D in the first transporting direction W1 (conveying direction W) by rotating in the second rotation direction R2.

The second stirring and transporting member 57 is juxtaposed with the first stirring and transporting member 56 in the second developer stirring and transporting chamber 512. The second stirring and transporting member 57 has a rotating shaft 571 and a spiral stirring and transporting unit 572. The rotation shaft 571 is rotatably supported by both side walls 513 and 514. The stirring and transporting unit 572 is provided on the rotating shaft 571 and is configured to transport the developer D in the second transporting direction W2 (L2 direction) by rotating in the first rotating direction R1.

A drive gear GR (drive transmission member) is provided at the end of L1 on one side of the second stirring and transporting member 57. The image forming apparatus main body 1 is provided with a rotation driving unit 120 (see FIG. 6), and the rotation driving unit 120 and the drive gear GR are connected to each other in a state where the developing device 5 is mounted on the image forming apparatus main body 1. , The rotational driving force of the rotational driving unit 120 is transmitted to the driving gear GR. A drive transmission means 59 is provided in the first stirring and transporting member 56 and the second stirring and transporting member 57. The drive transmission means 59 transmits the rotational driving force from the drive gear GR from the second stirring transfer member 57 to the first stirring transfer member 56.

The drive transmission means 59 has a clutch 591. By switching the clutch 591, the rotational driving force input to the second stirring and transporting member 57 is turned on / off. For example, by temporarily disengaging the clutch 591 while rotating the first stirring and transporting member 56 and the second stirring and transporting member 57, the first stirring and transporting member 56 and the second stirring and transporting member 57 are rotated. It is possible to make a difference in angle (phase difference). For example, by turning on / off the clutch 591 at the timing when the image formation by the image forming apparatus 100 is stopped, the first stirring transfer member 56 and the second stirring transfer member 57 can be pressed without affecting the image formation. A difference in rotation angle (phase difference) can be added.

FIG. 5 is a schematic plan view schematically showing the flow of the developer D housed in the developing tank 51.

As shown in FIG. 5, the partition member 58 is provided between the first developer stirring and transporting chamber 511 and the second developer stirring and transporting chamber 512. The partition member 58 forms a transport path for the developer D by the first stirring and transporting member 56 and the second stirring and transporting member 57. The first developer stirring and transporting chamber 511 and the second developing agent stirring and transporting chamber 512 are communicated with each other by the first communication section 510a and the second communication section 510b. The first communication portion 510a is composed of an open portion at one end of the partition member 58 on one side L1. The second communication portion 510b is composed of an open portion at the L2 end on the other side of the partition member 58. The first communication section 510a causes the developer D to flow out in the third transport direction W3 (transport direction W), and the second communication section 510b causes the developer D to flow out in the fourth transport direction W4 (convey direction W).

The developer D housed in the first agitating and conveying chamber 511 is conveyed in the first conveying direction W1 while being agitated by the first agitating and conveying member 56. The developer D reaches the second developer stirring and transporting chamber 512 from the first developer stirring and transporting chamber 511 by passing through the first communication portion 510a. The developer D housed in the second developer stirring and transporting chamber 512 is transported in the second transporting direction W2 while being stirred by the second stirring and transporting member 57. The developer D reaches the first developer stirring and transporting chamber 511 from the second developer stirring and transporting chamber 512 by passing through the second communication portion 510b. In this way, the developer D is conveyed so as to circulate between the first developer stirring and transporting chamber 511 and the second developer stirring and transporting chamber 512 while being stirred in the developing tank 51.

The developing apparatus 5 further includes a trickle discharging unit 200, a developing agent discharging screw 519, and a discharging port 517.

The trickle discharging unit 200 discharges the surplus developing agent D out of the developing agent D housed in the developing tank 51 to the outside of the developing tank 51. In the present embodiment, the trickle discharging section 200 is provided on the upstream side of the first stirring transport member 56 in the first transport direction W1 and on the upstream side of the first communication section 510b in the first transport direction W1.

The developer discharge screw 519 transports the developer D discharged from the first developer stirring and transport chamber 511 toward the recovery container 90 in the trickle discharge unit 200. The developer discharge screw 519 has a spiral discharge transport unit 518. The discharge transport unit 518 is provided on the rotating shaft 561 of the first stirring transport member 56. The discharge transport unit 518 is attached in the same twisting direction as the stirring transport unit 562 of the first stirring transport member 56 and at a short pitch.

The discharge port 517 discharges the excess developer D conveyed by the developer discharge screw 519 toward the recovery container 90. In the developing tank 51, a specified amount or a substantially specified amount of the developing agent D is secured by sequentially repeating the supply of the toner T and the carrier C to the developing tank 51 and the discharge of the surplus developing agent D from the developing tank 51. The deteriorated carrier C can be replaced with a new carrier C. As a result, deterioration of image quality can be suppressed while maintaining the charging performance of the toner T.

The developer D is transported so as to circulate between the first developer stirring and transporting chamber 511 and the second developer stirring and transporting chamber 512, and the developer D that has been transported through the second developer stirring and transporting chamber 512. Is transported to the trickle discharge section 200 without moving to the first developer stirring and transport chamber 511 via the second communication section 510b. A part of the developer D conveyed to the position of the trickle discharge unit 200 is discharged toward the developer discharge screw 519 as a surplus developer D.

FIG. 6 is a block diagram showing a system configuration of the control unit 300 in the image forming apparatus 100.

As shown in FIG. 6, the image forming apparatus 100 further includes a control unit 300. The control unit 300 has a processing unit 310 composed of a microcomputer such as a CPU (Central Processing Unit) and a storage unit 320 including a non-volatile memory such as a ROM and a volatile memory such as a RAM. The control unit 300 controls the operation of various components by the processing unit 310 loading the control program stored in the ROM of the storage unit 320 in advance into the RAM of the storage unit 320 and executing the control program. Thereby, each component of the image forming unit 30 can be controlled.

A toner concentration sensor 410, a temperature / humidity sensor 420, and a counter 430 are electrically connected to the input system of the control unit 300.

The toner concentration sensor 410 is arranged in the developing tank 51 of the developing device 5 and detects the concentration of the toner T contained in the developing agent D.

The temperature / humidity sensor 420 measures the temperature and humidity of the environment in which the image forming apparatus 100 is installed.

The counter 430 counts the number of recording materials P related to image formation, and measures the life of the developing agent D (the degree of deterioration of the developing agent D) from the number of recording materials P.

A rotary drive unit 120 and a clutch 591 are electrically connected to the output system of the control unit 300.

The rotation drive unit 120 is provided in the image forming apparatus main body 1, and outputs a rotation drive force for driving the first stirring transfer member 56 and the second stirring transfer member 57 of the developing device 5.

The clutch 591 is provided in the developing device 5, and when the clutch 591 is switched, the rotational driving force input to the second stirring and transporting member 57 is turned on / off. The control unit 300 controls the operation of the clutch 591 by the instruction signal to the clutch 591 to cause a difference in rotation angle (phase difference) between the first stirring and transporting member 56 and the second stirring and transporting member 57.

7 and 8 are plan views schematically showing the rotation angles of the first stirring and transporting member 56 and the second stirring and transporting member 57 and the transporting state of the developer. 9 is a cross-sectional view taken along the line BB of FIG. 7, and FIG. 10 is a cross-sectional view taken along the line CC of FIG.

In the state shown in FIGS. 7 and 9, the stirring and transporting section 562 of the first stirring and transporting member 56 and the stirring and transporting section 572 of the second stirring and transporting member 57 are in a state of facing each other.

Specifically, as shown in FIG. 9, the virtual line extending from the center of the rotating shaft 561 of the first stirring and transporting member 56 to the stirring and transporting unit 562 is L1, and from the center of the rotating shaft 571 of the second stirring and transporting member 57. Assuming that the virtual line extending to the stirring and transporting unit 572 is L2, the virtual line L1 and the virtual line L2 are parallel to each other. In this state, the relative position of the second stirring and transporting member 57 with respect to the first stirring and transporting member 56, that is, the difference (phase difference) in the rotation angle of the second stirring and transporting member 57 with respect to the first stirring and transporting member 56 is 0 degrees. be.

When the difference (phase difference) in the rotation angles of the second stirring and transporting member 57 with respect to the first stirring and transporting member 56 is 0 degrees, the first stirring and transporting member 56 and the second stirring and transporting member 57 are in the second rotation direction R2 and R2, respectively. When rotating at the same rotation speed in the first rotation direction R1, the stirring and transporting section 562 of the first stirring and transporting member 56 and the stirring and transporting section 57 of the second stirring and transporting member 57 rotate while facing each other at opposite positions. ..

Therefore, as shown in FIG. 7, when the developer D is sent from the second developer stirring and transporting chamber 512 to the first developing agent stirring and transporting chamber 511 via the second communicating portion 510b, the developing agent D is among the stirring and transporting portions 572. The portion (hatching portion) facing the second communication portion 510b is directed toward the second communication portion 510b, and at the timing when the developer D is sent out to the second communication portion 510b, the second communication portion 510b of the stirring and conveying portion 562 The facing portion (hatching portion) is directed toward the second communication portion 510b, and the positional relationship is such that the developer D is pushed back to the second communication portion 510b.

In other words, as shown in FIG. 9, the distance D1 from the stirring and transporting section 562 to the second communication section 510b in the plan view and the distance D2 from the stirring and transporting section 572 to the second communicating section 510b in the plan view. Is in a state where and is almost the same.

In this way, when the developer D is pressed against each other by the stirring and transporting unit 562 and the stirring and transporting unit 572 and the delivery amount of the developer D in the second communication section 510b decreases, the retention amount of the developer D in the second communication section 510b increases. To increase. Then, as shown in FIG. 7, the developer D easily reaches the trickle discharge unit 200, the developer D is easily discharged to the outside of the developing tank 51, and the amount of the developing agent D in the developing tank 51 decreases. ..

On the other hand, in the state shown in FIGS. 8 and 10, the stirring and transporting section 562 of the first stirring and transporting member 56 and the stirring and transporting section 57 of the second stirring and transporting member 57 are in a state of contradictory to each other.

Specifically, as shown in FIG. 10, the virtual line extending from the center of the rotating shaft 561 of the first stirring and transporting member 56 to the stirring and transporting unit 562 is L1, and from the center of the rotating shaft 571 of the second stirring and transporting member 57. Assuming that the virtual line extending to the stirring and transporting unit 572 is L2, the virtual line L1 and the virtual line L2 intersect so as to form an angle θ. In FIG. 10, the angle θ = 90 degrees. In this state, the relative position of the second stirring and transporting member 57 with respect to the first stirring and transporting member 56, that is, the difference (phase difference) in the rotation angle of the second stirring and transporting member 57 with respect to the first stirring and transporting member 56 is θ = 90. Degree.

When the difference (phase difference) in the rotation angles of the second stirring and transporting member 57 with respect to the first stirring and transporting member 56 is 90 degrees, the first stirring and transporting member 56 and the second stirring and transporting member 57 are in the second rotation direction R2 and R2, respectively. When rotated at the same rotation speed in the first rotation direction R1, the agitation transfer section 562 of the first agitation transfer member 56 and the agitation transfer section 57 of the second agitation transfer member 57 are in opposite positions at opposite positions. It will rotate.

Therefore, as shown in FIG. 8, when the developer D is sent from the second developer stirring and transporting chamber 512 to the first developer stirring and transporting chamber 511 via the second communicating portion 510b, the developing agent D is among the stirring and transporting portions 572. At the timing when the portion (hatching portion) facing the second communication portion 510b is directed toward the second communication portion 510b and the developer D is sent out to the second communication portion 510b, the second communication portion 510b of the stirring and transporting portions 562 Since the facing portion (hatching portion) is directed in a direction different from that of the second communication portion 510b, the positional relationship is such that the developer D is received from the second communication portion 510b.

In other words, as shown in FIG. 10, the distance D1 from the stirring and transporting section 562 to the second communication section 510b in the plan view and the distance D2 from the stirring and transporting section 572 to the second communicating section 510b in the plan view. Is in a different state.

In this way, when the developer D is smoothly delivered from the stirring and transporting unit 572 to the stirring and transporting unit 562 and the amount of the developing agent D delivered in the second communication section 510b increases, the retention amount of the developing agent D in the second communication section 510b increases. Decreases. Then, it becomes difficult for the developer D to reach the trickle discharge unit 200, the developer D becomes difficult to be discharged to the outside of the developing tank 51, and the amount of the developing agent D in the developing tank 51 increases. That is, the decrease in the amount of the developer D in the developing tank 51 is suppressed.

In the present invention, the retention amount of the developer D in the second communication portion 510b is adjusted by changing the difference (phase difference) in the rotation angles between the first stirring and transporting member 56 and the second stirring and transporting member 57. The amount of the developer D discharged from the trickle discharge unit 200 is changed.

In the present embodiment, the amount of the developing agent D discharged from the trickle discharging unit 200 by the system configuration including the first stirring and transporting member 56, the second stirring and transporting member 57, the clutch 591, and the control unit 300 shown in FIG. Consists of a developer retention adjusting unit 500 that changes the temperature.

The developer retention adjusting unit 500 changes the phases of the first stirring and transporting member 56 and the second stirring and transporting member 57 according to the toner concentration, the temperature and humidity of the surrounding environment, the degree of deterioration of the developer D, and the like, and develops the developing agent suitable for each condition. Discharge agent D. Hereinafter, a case where the phases of the first stirring and transporting member 56 and the second stirring and transporting member 57 are changed according to the change of the conditions will be described with reference to an example.

[Fluctuation of toner concentration (when toner concentration rises)]
When the toner concentration increases, the volume of the developer D increases because the amount of the toner T with respect to the carrier C increases. Since the volume-increasing developer D is discharged from the trickle discharge unit 200, the amount of the developer D in the developing tank 51 is temporarily reduced. As a result, the amount of the developer D picked up from the first stirring and transporting member 56 to the developing roller 53 (the amount of the developer D transported by the developing roller 53) is reduced, and image unevenness is likely to occur temporarily.

When the toner concentration increases in this way, after detecting the toner concentration by the toner concentration sensor 410 in the developing tank 51, the control unit 300 switches the clutch 591 to adjust the rotation angle of the second stirring and transporting member 57. A difference is made in the rotation angle of the second stirring and transporting member 57 with respect to the first stirring and transporting member 56 (for example, the difference in the rotation angle is 90 degrees (see FIGS. 8 and 10)).

By making a difference in the rotation angle of the second stirring and transporting member 57 with respect to the first stirring and transporting member 56, the developing agent D is smoothly transferred from the stirring and transporting unit 572 to the stirring and transporting unit 562, and the developing agent D in the second communicating portion 510b. The amount delivered is increased, and the amount of the developer D retained in the second communication portion 510b is reduced. As a result, it becomes difficult for the developer D to reach the trickle discharge unit 200, excessive discharge of the developer D is suppressed, and the amount of the developer D in the developing tank 51 increases (the decrease in the amount of the developer D is suppressed). Will be). As a result, the decrease in the amount of the developer D picked up from the first stirring and transporting member 56 to the developing roller 53 (the amount of the developer D transported by the developing roller 53) is improved, and temporary image unevenness is suppressed.

[Fluctuation of toner concentration (when toner concentration decreases)]
When the toner concentration decreases, the amount of toner T with respect to the carrier C decreases, so that the volume of the developer D decreases. In this state, the position of the upper surface of the developer D with respect to the developing roller 53 is lowered, and the amount of the developer D picked up from the first stirring transfer member 56 to the developing roller 53 (the amount of the developer D conveyed by the developing roller 53) is increased. It is lowered and tends to cause image unevenness temporarily.

When the toner concentration drops in this way, after detecting the toner concentration by the toner concentration sensor 410 in the developing tank 51, the control unit 300 switches the clutch 591 to adjust the rotation angle of the second stirring and transporting member 57. The difference in the rotation angle of the second stirring and transporting member 57 with respect to the first stirring and transporting member 56 is reduced (for example, the difference in the rotation angle is set to 0 degrees (see FIGS. 7 and 9)).

By reducing the difference in the rotation angle of the second stirring and transporting member 57 with respect to the first stirring and transporting member 56, it becomes difficult to deliver the developer D from the stirring and transporting unit 572 to the stirring and transporting unit 562, and the developing agent in the second communicating portion 510b becomes difficult. By increasing the retention amount of D, the position of the upper surface of the developer D with respect to the developing roller 53 can be raised. As a result, the decrease in the amount of the developer D picked up from the first stirring and transporting member 56 to the developing roller 53 (the amount of the developer D transported by the developing roller 53) is improved, and temporary image unevenness is suppressed.

[Environmental change (low temperature and low humidity environment)]
As the operating environment of the image forming apparatus 100 changes, the fluidity and the like of the developer D in the developing tank 51 change. For example, in a low temperature and low humidity environment, the toner T has a high chargeability, a large volume, and good fluidity.

When the operating environment is low temperature and low humidity, the control unit 300 switches the clutch 591 to adjust the rotation angle of the second stirring and transporting member 57 after detecting the temperature and humidity by the temperature and humidity sensor 420, and first stirring. A difference is made in the rotation angle of the second stirring transfer member 57 with respect to the transfer member 56 (for example, the difference in the rotation angle is 90 degrees (see FIGS. 8 and 10)).

By making a difference in the rotation angle of the second stirring and transporting member 57 with respect to the first stirring and transporting member 56, the developing agent D is smoothly transferred from the stirring and transporting unit 572 to the stirring and transporting unit 562, and the developing agent D in the second communicating portion 510b. The amount delivered is increased, and the amount of the developer D retained in the second communication portion 510b is reduced. As a result, it becomes difficult for the developer D to reach the trickle discharge unit 200, excessive discharge of the developer D is suppressed, and the amount of the developer D in the developing tank 51 increases (the decrease in the amount of the developer D is suppressed). Will be). As a result, the decrease in the amount of the developer D picked up from the first stirring and transporting member 56 to the developing roller 53 (the amount of the developer D transported by the developing roller 53) is improved, and temporary image unevenness is suppressed.

[Environmental change (high temperature and high humidity environment)]
In a high temperature and high humidity environment, the chargeability of the toner T is low, the volume is small and it is easy to sink (the volume of the developer D is reduced), and the fluidity is also low. In this case, the amount of the developer D picked up from the first stirring and transporting member 56 to the developing roller 53 tends to decrease due to the sinking of the developer D.

When the operating environment is high temperature and high humidity in this way, after detecting the temperature and humidity by the temperature and humidity sensor 420, the control unit 300 switches the clutch 591 to adjust the rotation angle of the second stirring and transporting member 57, and the first The difference in the rotation angle of the second stirring and transporting member 57 with respect to the stirring and transporting member 56 is reduced (for example, the difference in the rotation angle is set to 0 degrees (see FIGS. 7 and 9)).

By reducing the difference in the rotation angle of the second stirring and transporting member 57 with respect to the first stirring and transporting member 56, it becomes difficult to deliver the developing agent D from the stirring and transporting unit 572 to the stirring and transporting unit 562, and the developing agent in the second communicating portion 510b becomes difficult. By increasing the retention amount of D, the position of the upper surface of the developer D with respect to the developing roller 53 can be raised, and the amount of the developer D picked up from the first stirring and transporting member 56 to the developing roller 53 can be increased. .. Further, by positively increasing the height of the developer D in the trickle discharge unit 200, it is possible to suppress the deterioration of the discharge performance of the developer D due to the decrease in the fluidity of the developer D and the clogging of the developer D. can do.

[Deterioration of developer]
In the trickle development method, the deterioration of the developer D does not continue to decrease and settles at a certain value, but the period immediately after the start of use of the developer D (initial) and the period when the developer D is used for a predetermined period ( At the time of life), the state of the developer D is different. Initially, the developer D has a high chargeability and a large volume (the volume of the developer D increases), but at the time of life, the chargeability of the developer D decreases and the developer D easily sinks (the developer D). Volume decreases).

When the degree of deterioration of the developer D changes in this way, after detecting the degree of deterioration of the developer D from the number of recording materials P by the counter 430, the control unit 300 switches the clutch 591 and the second stirring and conveying member 57. The difference in the rotation angle of the second stirring and transporting member 57 with respect to the first stirring and transporting member 56 is changed by adjusting the rotation angle of the above. For example, as the degree of deterioration of the developer D progresses, the difference in the rotation angle of the second stirring and transporting member 57 with respect to the first stirring and transporting member 56 is gradually reduced. As a result, the discharge performance of the developer D deteriorates due to the decrease in the fluidity of the developer D, and the amount of the developer D picked up from the first stirring and transporting member 56 to the developing roller 53 (the developer D in the developing roller 53). It is possible to suppress a decrease in the amount of transport).

In the above description, the difference in the rotation angle of the second stirring and transporting member 57 with respect to the first stirring and transporting member 56 is 0 degree or 90 degrees, but the difference with respect to the first stirring and transporting member 56 is in the range of 0 to 360 degrees. 2 The difference in the rotation angle of the stirring and transporting member 57 can be adjusted. By changing the difference in the rotation angle of the second stirring and transporting member 57 with respect to the first stirring and transporting member 56, the retention amount of the developer D in the second communication portion 510b can be adjusted, and the developer discharged from the trickle discharging portion 200. The amount of D can be varied.

[Embodiment 2]
In the first embodiment, the trickle discharge unit 200 is on the upstream side of the first transfer direction W1 of the first stirring transfer member 56 provided near the developing roller 53, and is in the first transfer direction with respect to the second communication portion 510b. It is provided on the upstream side of W1. In the second embodiment, the trickle discharging section 200A is on the downstream side of the second stirring transport member 57 located at a position away from the developing roller 53 in the second transport direction W2, and is second than the second communication section 510b. It is provided on the downstream side of the transport direction W2. In the following description, the same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted, and only the configurations different from the first embodiment will be described.

FIG. 11 is a schematic plan view schematically showing the flow of the developer D housed in the developing tank 51A in the developing apparatus 5A according to the second embodiment of the present invention.

Even when the trickle discharging portion 200A is provided at the position shown in FIG. 11, the difference (phase difference) in the rotation angles between the first stirring and transporting member 56 and the second stirring and transporting member 57 is changed to change the second communication portion. By adjusting the retention amount of the developer D in 510b, the amount of the developer D discharged from the trickle discharge unit 200A can be changed.

[Embodiment 3]
In the third embodiment, the trickle discharge unit 200B is provided on the side wall of the developing tank 51B away from the developing roller 53.

FIG. 12 is a schematic plan view schematically showing the flow of the developer D housed in the developing tank 51B in the developing apparatus 5B according to the third embodiment of the present invention.

Even when the trickle discharging portion 200B is provided at the position shown in FIG. 12, the difference (phase difference) in the rotation angles between the first stirring and transporting member 56 and the second stirring and transporting member 57 is changed to change the second communication portion. By adjusting the retention amount of the developer D in 510b, the amount of the developer D discharged from the trickle discharge unit 200B can be changed.

[Embodiment 4]
In the fourth embodiment, the first stirring and transporting member 56C and the second stirring and transporting member 57C are provided with paddles 565 and 575.

FIG. 13 is a plan view showing a first stirring and transporting member 56C and a second stirring and transporting member 57C in the developing apparatus 5C according to the fourth embodiment of the present invention.

As shown in FIG. 13, the first stirring and transporting member 56C is provided with a paddle 565 extending in a direction intersecting the stirring and transporting unit 562C. The paddle 565 has a plate-like shape and is provided at a position close to the second communication portion 510b.

Similar to the first stirring and transporting member 56C, the second stirring and transporting member 57C is provided with a paddle 575 extending in a direction intersecting the stirring and transporting unit 572C. The paddle 575 has a plate-like shape and is provided at a position close to the second communication portion 510b.

Since the paddles 565 and 575 extend in the direction intersecting the stirring and transporting portions 562C and 572C, the amount of the developer D transferred between the first stirring and transporting member 56C and the second stirring and transporting member 57C increases. Therefore, by changing the difference (phase difference) in the rotation angles between the first stirring and transporting member 56C and the second stirring and transporting member 57C, the relative positions of the stirring and transporting portions 562C, 572C and the paddles 565 and 575 are changed. The amount of retention of the developer D in the second communication portion 510b can be significantly changed. As a result, the amount of the developer D discharged from the trickle discharging unit 200C can be easily changed.

[Modification example]
The present invention is not limited to the embodiments described above, and can be implemented in various other forms. Therefore, such embodiments are merely exemplary in all respects and should not be construed in a limited way. The scope of the present invention is shown by the claims and is not bound by the text of the specification. Furthermore, all modifications and modifications that fall within the equivalent scope of the claims are within the scope of the present invention.

For example, in the above embodiment, the first stirring transfer member 56 and the second stirring transfer member 57 are provided with a difference in rotation angle (phase difference) by switching the clutch 591, but the present invention is not limited to this. For example, the image forming apparatus main body 1 is provided with a first rotation drive unit and a second rotation drive unit for individually inputting a rotation drive force to the first stirring transfer member 56 and the second stirring transfer member 57, and the first rotation drive unit and the first rotation drive unit and the second rotation drive unit 57 are provided. A difference in rotation angle (phase difference) may be added to the first stirring and transporting member 56 and the second stirring and transporting member 57 by changing the rotational driving force of the second rotary driving unit. In this case, the relative positions of the stirring and transporting portions 562 and 572 in the first stirring and transporting member 56 and the second stirring and transporting member 57 can be changed without complicating the configuration of the developing device 5.

100 Image forming device 5 Developing device 50 Stirring and transporting member 51 Developing tank 53 Developing roller (developer carrier)
200 Trickle discharge part 510b 2nd communication part (communication part)
511 First developer stirring transfer chamber 512 Second developer stirring transfer chamber 500 Developer retention adjustment unit D Developer

Claims (8)

A developing tank having a first developer stirring and transporting chamber and a second developing agent stirring and transporting chamber and accommodating the developing agent,
A stirring and transporting member that transports the developer contained in the first developer stirring and transporting chamber and the second developing agent stirring and transporting chamber in a predetermined transport direction while stirring.
A developer carrier that supports a developer that has been stirred and transported by the stirring and transporting member, and a developer carrier.
A communication portion that communicates the first developer stirring and transporting chamber and the second developing agent stirring and transporting chamber on one and the other end sides of the developing tank.
A trickle discharge unit provided in the developing tank and discharging the developer contained in the developing tank to the outside of the developing tank.
It is a trickle development type developing device equipped with
A developer retention adjusting unit for changing the amount of the developer discharged from the trickle discharge unit by adjusting the retention amount of the developer in the communication unit is provided.
Developing equipment. The developing apparatus according to claim 1.
Equipped with a detector that detects the surrounding environment and / or operating conditions
The developer retention adjusting unit adjusts the retention amount of the developer in the communication unit based on the detection result of the detection unit.
Developing equipment. The developing apparatus according to claim 1 or 2.
The agitation transfer member includes a first agitation transfer member and a second agitation transfer member each having a spiral agitation transfer section.
The developer retention adjusting unit is
By changing the relative positions of the stirring and transporting portion in the first stirring and transporting member and the second stirring and transporting member, the retention amount of the developer in the communicating portion is adjusted.
Developing equipment. The developing apparatus according to claim 3.
The developer retention adjusting unit is
When the first stirring and transporting member and the second stirring and transporting member are operating, the distance from the stirring and transporting portion of the first stirring and transporting member to the communicating portion in a plan view and the second stirring and transporting member in a plan view. By matching or differentizing the distance from the stirring and transporting section to the communicating section, the relative positions of the stirring and transporting section in the first stirring and transporting member and the second stirring and transporting member are changed.
Developing equipment. The developing apparatus according to claim 3 or 4.
The developer retention adjusting unit is
It has a clutch for transmitting a driving force for driving the first stirring and transporting member and / or the second stirring and transporting member.
By switching the clutch, the relative phases of the first stirring and transporting member and the stirring and transporting portion of the second stirring and transporting member are changed.
Developing equipment. The developing apparatus according to claim 3 or 4.
The developer retention adjusting unit is
The first drive transmission unit into which the driving force for driving the first stirring and transporting member is input, and
A second drive transmission unit to which a driving force for driving the second stirring and transporting member is input, and
Have,
By changing the driving force input to the first drive transmission unit and the second drive transmission unit, the relative phases of the first stirring transfer member and the second stirring transfer member are changed. Let,
Developing equipment. The developing apparatus according to any one of claims 3 to 6.
The first stirring and transporting member and / or the second stirring and transporting member is provided with a paddle extending in a direction intersecting the stirring and transporting portion.
The developer retention adjusting unit is
By changing the relative positions of the stirring and transporting portion and the paddle in the first stirring and transporting member and the second stirring and transporting member, the retention amount of the developer in the communicating portion is adjusted.
Developing equipment. The developing apparatus according to any one of claims 1 to 7 is provided.
Image forming device.

Images