JP2014021359A - Developing device, process cartridge, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device configured to properly supply developer while preventing increase in load to a driving source of a conveyance member, in conveying the developer in a direction opposite to the gravitational direction.SOLUTION: In a developing device 3, a supply-side agitation member 304 for supplying developer opposite to a developing sleeve and a collection-side agitation member 305 for agitating and conveying the developer collected after development from the developing sleeve are arranged vertically, to convey the developer in a direction opposite to the gravitational direction. The developing device is driven for a predetermined time in a direction opposite to the developer conveyance direction according to the time elapsed from when the agitation members are stopped, to soften the developer accumulated in a communication part 307 between the supply side and the collection side, thereby reducing drive resistance when the agitation members 304, 305 are restarted.

Description

  The present invention relates to a developing device, a process cartridge, and an image forming apparatus, and more particularly, to a developing mechanism that uses a two-component developer including toner and a carrier.

In an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a printing machine that uses an electrophotographic system, a latent image bearing member formed on a photosensitive member is subjected to a visible image processing by a developing device, A recorded output can be obtained by transferring the visible image to a sheet or the like.
As a developer used for development, there is a two-component developer obtained by mixing a toner and a carrier in addition to a one-component developer containing only magnetic or non-magnetic toner.
The two-component developer is composed of a toner and a carrier that carries the toner, and the toner is charged by a frictional charging action that occurs during agitation and mixing to form a development area where an electrostatic latent image is formed on the photoreceptor. Be transported.

  The developing device includes a developing sleeve as a developer carrying member that causes a developer to rise on the peripheral surface by a magnetic force from a magnetic pole disposed therein and supplies the developer toward an electrostatic latent image on the photosensitive member. First and second developer agitating and conveying members composed of screw augers and the like that can bisect the inside of the accommodated developer tank and convey the developer while stirring the developer in opposite directions to each other. Configurations provided are known.

  In the above configuration, the first developer stirring and conveying member supplies the developer mixed with stirring to the developing sleeve, and the second developer stirring and conveying member conveys the developer and the replenished toner while stirring and mixing. The first developer agitating and conveying member is conveyed to the space where it is located.

The above-described spaces communicate with each other at both ends in the developer transport direction, and the developer circulates in each space by the first and second developer agitation transport members.
The second developer agitating and conveying member is agitated and mixed in the developer when new toner is replenished according to the concentration of the developer collected from the space where the first developer agitating and conveying member is disposed. Then, the developer is fed again to the space where the first developer stirring and conveying member is located.

In the juxtaposed structure of the first and second developer agitating / conveying members, these agitating / conveying members may be juxtaposed in the horizontal direction.
FIG. 10 shows an example in which developer agitating and conveying members are juxtaposed in the horizontal direction.
In FIG. 10, a developing sleeve that processes the electrostatic latent image on the photosensitive member facing the photosensitive member is provided in the developing tank, and the developing tank is divided into two horizontal spaces by a partition wall. ing.
Each developer agitating and conveying member has the same structure, and conveys the developer in opposite directions.

In the configuration described above, the developer capacity of the developer can be made substantially uniform in the transport direction of the developer stirring and transporting member.
However, in the space where the developer agitating / conveying member on the side facing the developing sleeve is disposed, the developer whose toner density is reduced due to the development is also collected and conveyed. For this reason, the developer moving toward the downstream side in the transport direction is supplied again to the developing sleeve in the moving process, and the density of the developer carried on the developing sleeve is not uniform. May cause unevenness.

Therefore, in order to make the toner density in the developer carried on the developing sleeve uniform, a configuration has been proposed in which the developer plate transport members are juxtaposed in the vertical direction (for example, Patent Document 1).
Patent Document 1 discloses a developer in which a space in which developer plate transport members are arranged is partitioned in a vertical direction, and developer recovered from a developing sleeve is disposed in a developer plate transport member facing the developer. A configuration is disclosed in which the developer is moved toward the developer stirring and conveying member disposed in the lower space instead of the supply side space.
The developer collected in the lower space is agitated and conveyed by the developer agitating / conveying member together with the toner replenished according to the toner concentration, and the supply side located above via the communicating portion provided on the downstream side in the conveying direction. Transferred to space.

  In the above-described configuration, the developer whose toner concentration is insufficient from the developing sleeve is not collected in the supply side space, and the developer having the optimized toner concentration is supplied to the supply side space from the lower space.

However, the above-described configuration has the following problems because the developer is transported from the lower space toward the supply side space located above.
At the position communicating from the space located below to the supply side space located above, the developer transport direction is the antigravity direction, and therefore the developer collected in this portion when the developer transport is stopped. Becomes a transport load when transport is resumed, and causes an increase in load on the drive source. The reason is as follows.

FIG. 11 is a diagram showing the distribution of the developer in the developing tank. As shown in FIG. 11, in the space SF where the developer agitating and conveying member facing the developing sleeve is arranged, toner is conveyed during the conveying process. When consumed, the developer amount decreases as it reaches the downstream side in the transport direction.
On the other hand, in the space SM in which the developer agitating and conveying member that agitates and conveys the collected developer is disposed, the bulk increases from the upstream side to the downstream side in the conveying direction.
For this reason, in the communicating portions in the upper and lower spaces, in particular, the communicating portion on the side where the developer is pushed up in the antigravity direction and transferred to the upper supply side space, the bulkiness is high on the downstream side in the lower space side. In other words, the developer is filled.

  If transport of the developer is stopped in such a state, the developer accumulated in the communication portion becomes a rotational resistance with respect to the developer stirring and transporting member when transport is resumed, and as a result, the developer stirring and transporting member is driven. There is a risk that normal transportation cannot be resumed due to an increase in load on the source.

As the developer stirring and conveying member used for stirring and conveying the developer, a rotating member is used like a screw auger. For this reason, the rotating member is often rotatably supported by a mechanical component such as a bearing.
However, there are cases in which the mechanical parts of the mechanical parts change their steady mechanical dimensions due to temperature changes in the usage environment, and rotational resistance may be generated by the change in the mechanical dimensions.
For example, a mechanical component such as a bearing contracts under the low temperature environment from the mechanical dimensions in the Uemura environment, and the rotational resistance to the rotating shaft due to the contraction may increase.

  As described above, in the conventional configuration, consideration is given to the operation status of the developer agitating / conveying member, that is, the increase in rotational resistance due to the temperature change in the usage environment at the start of developer conveyance from the stop to the resumption of operation. In other words, there is no way to prevent an increase in driving load at the driving source of the developer agitating / conveying member and assure proper supply of the developer by smooth developer conveyance.

  An object of the present invention is to prevent an increase in load on a driving source of a conveyance member and to appropriately supply a developer, particularly in the case of targeting developer conveyance in an antigravity direction, in view of problems in a conventional developing device. An object of the present invention is to provide a developing device, a process cartridge, and an image forming apparatus having a possible configuration.

In order to achieve this object, the present invention provides a rotatable developing sleeve for supplying a developer to an electrostatic latent image formed on an electrostatic latent image carrier, and an axis of the developing sleeve arranged parallel to each other. A rotatable developer supply member that supplies the developer to the developer sleeve, a rotatable developer recovery member that stirs the developer collected from the developer sleeve, the development sleeve, the developer supply member, and the development A developing device comprising at least a casing having a space in which the agent collecting member can be disposed and having an opening exposing a part of the developing sleeve to the outside and a toner replenishing portion;
The spaces where the developer supply member and the developer recovery member are arranged are partitioned except for a part of the communication portion,
A drive source for driving the developer and the developer recovery member so that the transport direction of the developer in each partitioned space is in the opposite direction;
A control unit capable of switching the drive direction of the drive source,
The control unit has a timer connected to the input side connected to the input side and a drive source connected to the output side connected to the input side. When it is determined that the supply member and the developer recovery member have been left for a specified time, the drive in the direction opposite to the normal developer transport direction is predetermined before the developer supply member and the developer recovery member are restarted. The developing device is characterized in that it is performed for a long time.

  According to the present invention, each member is driven in a direction opposite to that during conveyance for a predetermined time in accordance with the leaving time from the stop of the developer supply member and developer recovery member. It is possible to loosen the developer accumulated in the communication portion provided in the portion. As a result, the rotational load caused by the developer when the developer supply member and the developer recovery agent are restarted is reduced.

FIG. 2 is a schematic diagram for explaining an embodiment of an image forming apparatus using a developing device. It is a schematic diagram for demonstrating the principal part structure used for one Embodiment of a developing device. FIG. 3 is a schematic diagram for explaining an operation of a developing sleeve of the developing device shown in FIG. 2. FIG. 4 is a cross-sectional view for explaining the internal configuration of the developing sleeve shown in FIG. 3. FIG. 3 is a perspective view for explaining an installation structure and operation of a developer supply member and a developer recovery member used in the developing device shown in FIG. 2. FIG. 3 is an external view of the developing device shown in FIG. 2. FIG. 6 is a plan view showing a developer supply member and a developer recovery member shown in FIG. 5. It is a block diagram for demonstrating the structure of the control part used for the image development apparatus concerning embodiment of this invention. It is a flowchart for demonstrating the effect | action of the control part shown in FIG. It is a figure for demonstrating an example of the installation structure of a developing agent supply member and a developing agent collection | recovery member. It is a figure for demonstrating the distribution state of the developer in the developing device using the conventional developer movement system in the vertical direction.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the embodiments shown in the drawings.
FIG. 1 is a diagram showing a configuration of an image forming apparatus to which a developing device according to an embodiment of the present invention is applied. In FIG. 1, the image forming apparatus has the following configuration.
The image forming apparatus shown in FIG. 1 includes a plurality of image forming units 17K, 17M, 17Y, and 17C in order from the upstream side in the moving direction (conveying direction) of the conveying belt 15 along the conveying belt 15 that conveys the transfer paper 8. This is a color image forming apparatus that is so-called tandem type that is arranged. The order of colors is not limited to this. For example, it is possible to arrange black at the most downstream side and form an image in the order of MCYK.
Each color image forming unit is formed of a combination of a plurality of members to form an image. It is not necessarily configured as a unit.

The image forming unit 17K forms black, the image forming unit 17M forms magenta, the image forming unit 17Y forms yellow, and the image forming unit 17C forms cyan. The image forming units have different colors. However, the internal configuration is the same for each image forming unit.
Therefore, in the following description, the outline of the image forming unit 17K will be described. For the other image forming units, K added to the end of the reference numeral of each member in the image forming unit 17K, M for the image forming unit 17M, and the image The forming unit 17Y is replaced with Y, and the image forming unit 17C is replaced with C, and the description thereof is omitted.

  The conveyor belt 15 is composed of a driving roller, one of which is driven to rotate, and an endless belt that is rotatably supported by the conveying rollers 18, 19 that are driven rollers, the other of which is driven to rotate. , Can be rotated in the direction of the arrow.

Below the transport belt 15, paper feed trays 20, 21, and 22 that store the transfer paper 8 are provided.
For example, the transfer paper 8 at the uppermost position among the transfer papers 8 stored in the paper feed tray 20 is sent out at the time of image formation and is temporarily kept on standby by the registration roller 23, and the image formation and timing in the image forming unit 17K are set. They are fed together and attracted to the conveyor belt 15 by electrostatic attraction. In this way, the transfer paper 8 adsorbed to the conveyance belt 15 is conveyed to the first image forming unit 17K, where a black image is transferred.

The image forming unit 17K includes a member having the same configuration function as a member described later with reference to FIG. Those members having the same configuration function are denoted by the same reference numerals as those in FIG. 2 and subsequent figures, and are denoted by the photosensitive member 1K, the charging device 2K, the developing device 3K, and the like.
A transfer device 5K is arranged on the back side of the upper stretched portion of the conveyor belt 15, and a writing means 16 is provided as means for irradiating the photosensitive member 1 with exposure light L to form an electrostatic latent image. Is provided.

  When forming a color image, the image forming unit 17K uniformly charges the peripheral surface of the photoreceptor 1K by the charging device 2K in the dark, and then exposes the exposure light corresponding to the black image from the optical scanning device 16K. L is exposed to form an electrostatic latent image. This electrostatic latent image is visualized with black toner in the developing device 3K, and a black toner image is formed on the photoreceptor 1K.

This toner image is transferred onto the transfer paper 8 by the action of the transfer device 5K in alignment with the transfer paper 8 at a position where the photosensitive member 1K and the transfer paper 8 on the transport belt 15 come into contact, that is, a so-called transfer position. A monochromatic (black) image is formed on top. After the transfer, the photosensitive member 1K is freed of unnecessary toner remaining on the peripheral surface of the photosensitive member 1K by the cleaning device 6K, and is prepared for the next image formation.
In this way, the transfer paper 8 on which the single color (black) is transferred by the image forming unit 17K is transported to the next image forming unit 17M by the transport belt 15.

In the image forming unit 17M, the magenta toner image formed on the photoconductor 1M by the same process as in the image forming unit 17K is superimposed and transferred onto the black toner image on the transfer paper 8.
The transfer paper 8 is further conveyed to the next image forming unit 17Y, and the yellow toner image formed on the photoconductor 1Y in the same manner is overlaid on the black and magenta toner images already formed on the transfer paper 8. Is done. Similarly, in the next image forming unit 17C, a cyan toner image is transferred and overlapped to obtain a full color image.
The transfer paper 8 on which the full-color superimposed image is formed passes through the image forming portion 17C, is peeled off from the conveying belt 15, and is fixed by the fixing portion 24 while passing between the pair of fixing rollers. The paper is discharged to the paper tray 25.

  FIG. 2 is a diagram showing a configuration of a process cartridge used in the image forming unit. In FIG. 2, in the image forming unit 17 (for the sake of convenience, the alphabet for distinguishing colors is omitted), the photosensitive member 1 is rotated in the direction indicated by the arrow. A charging device 2 used for image forming processing along the rotation direction of the photoconductor 1, an exposure device (scanning light is indicated by symbol L), and a developing device are provided around the photoconductor 1. 3, a transfer device 5 and a cleaning device 6 are arranged.

  The charging device 2 is arranged on the upper portion of the photosensitive member 1 at a position of approximately 11 o'clock in terms of a clock face. In the case of the present embodiment, the charging device 2 is composed of a rotating body that rotates at the same speed as that of the photosensitive member 1, but is not limited to the rotating body and may be a corona discharge type.

  The surface of the photosensitive member 1 is uniformly charged in the dark by the charging device 2, and then an electrostatic latent image is formed by irradiation with exposure light L from writing means (not shown). The electrostatic latent image formed on the photosensitive member 1 by charging moves downstream as the photosensitive member 1 rotates and reaches the developing device 3. The developing device 3 is disposed on the right side of the photoreceptor 1 in FIG.

The developing device 3 includes an inside of a casing 301 corresponding to a developing container having a space capable of accommodating a two-component developer containing a carrier and a toner having a particle size set to 20 to 60 μm.
In the casing 301, the developer 320 is arranged in the vertical direction with respect to the rotation center O- 2 of the rotatable developing sleeve 302 and corresponds to a developer supplying member that can pump up the developer 320 that has been stirred and conveyed toward the developing sleeve 302. A recovery chamber transport member 305 corresponding to a developer recovery member that collects and conveys the developer after development from the supply chamber transport member 304 and the developing sleeve 302 is provided.
Further, in the vicinity of the developing sleeve 302, a developer developer layer thickness regulating member 303 such as a doctor blade for making the layer thickness of the developer carried on the developing sleeve 302 constant is provided.
In this case, the conveyance direction during the agitation conveyance is a direction perpendicular to the paper surface of FIG. 2, and the developer is transported in a direction perpendicular to the paper surface while rotating around during rotation.

The supply chamber transport member 304 corresponding to the developer supply member and the recovery chamber transport member 305 corresponding to the developer recovery member have the following arrangement configuration.
In the casing 301, it corresponds to a partition portion having a space C for storing the developer, which is extended from the inner wall of the container toward the space between both conveying members and pumped up by the supply chamber conveying member 304, toward the developer layer thickness regulating member 303. The partition plate 306 is divided into a developer supply chamber side and a recovery chamber side.

As described above, the developing sleeve 302 is opposed to the photosensitive member 1 at a position between 2 o'clock and 3 o'clock (position of 2:30) when expressed in a clock face, so that the developing nip region A is formed. They are arranged in close proximity so as to constitute.
A portion of the casing 301 corresponding to the portion facing the photoconductor 1 is opened to expose the developing sleeve 302.

The developer 320 in the casing 301 is conveyed to the development nip region A by the development sleeve 302.
The toner in the developer 320 adheres to the electrostatic latent image formed on the surface of the photoreceptor 1 in the development nip region A, and is visualized as a toner image. The toner image subjected to the visible image processing by the toner in the developer carried on the developing sleeve 302 moves to the downstream side with the rotation of the photosensitive member 1 and reaches the transfer device 5.

The transfer device 5 is arranged below the photosensitive member 1, that is, at the 6 o'clock position on the dial of the watch as described above.
In this embodiment, the transfer device 5 is composed of a rotating body, but is not limited to a rotating body, and may be a corona discharge type. A region where the photoreceptor 1 and the transfer device 5 face each other is referred to as a transfer region B.

The toner image on the photoreceptor 1 is transferred to the transfer paper 8 in the transfer region B and becomes an image on the transfer paper 8. Note that the present invention can also be applied to an intermediate transfer belt system in which the toner on the photosensitive member is once transferred to an intermediate transfer member (intermediate transfer belt or the like), and then the color toners are collectively transferred to transfer paper. In this case, the toner on the photosensitive member 1 is transferred to the intermediate transfer member (in this case, the conveyance belt 15 is used as the intermediate transfer belt) in the transfer region B.
After the transfer, the photosensitive member 1 moves downstream as the photosensitive member 1 rotates and reaches the cleaning device 6.

The cleaning device 6 is arranged at the 10 o'clock position.
The cleaning device 6 uses a cleaning blade 601 to remove toner remaining on the surface of the photoreceptor 1 without being completely transferred onto the transfer paper. The surface of the photoreceptor 1 that has passed through the cleaning device 6 is then uniformly charged by the charging device 2 and the next image forming process is repeated.

  In the developing device 3, the developer transported and stirred by the supply chamber transport member 304 corresponding to the developer supply member is supplied to the developer sleeve 302 after the layer thickness is regulated by the developer layer thickness regulating member 303. The developed developer moves toward a recovery chamber transport member 305 corresponding to a developer recovery member, and is further transported to the supply chamber side where the supply chamber transport member is located and circulates.

  FIG. 3 is a diagram for explaining the details of the developing device 3. In FIG. 3, the supply chamber transport member 304 and the recovery chamber transport member 305 are formed of a spiral screw capable of stirring and transporting the developer. A screw blade having an outer diameter of 16 mm or less is used.

In FIG. 3, the developing sleeve 302 has a magnet roller 302 d in which a plurality of magnets MG (only one is indicated by a reference numeral for preventing complication of the drawing) arranged in the circumferential direction, and the periphery thereof is cylindrical. The sleeve 302c is configured to rotate integrally with the rotary shaft 302e.
The sleeve 302c is made of a nonmagnetic metal such as aluminum.
The magnet roller 302d is fixed to an immovable member, for example, the casing 301, so that each magnet MG faces a predetermined direction, and a sleeve 302c rotates around the magnet roller MG to convey the developer 320 attracted by the magnet MG. To go.

In FIG. 4 showing the structure of the developing sleeve 302, the developing sleeve 302 is mainly composed of a fixed shaft 302a fixed to the stationary member casing 301, a magnet roller 302d having a cylindrical shape integrated with the fixed shaft 302a, and a magnet roller 302d. It consists of a sleeve 302c that is covered with a gap around and a rotating shaft 302e that is integral with the sleeve 302c.
The rotation shaft 302e is rotatable with respect to the fixed shaft 302a via a bearing 302f, and the rotation shaft 302e is driven to rotate by receiving power from a rotation driving means (not shown).

A plurality of magnets MG are fixed to the outer periphery of the magnet roller 302d at a predetermined interval as shown in FIG. The sleeve 302c rotates around these magnets MG.
These magnets MG are for forming a magnetic field so that the developer can be spiked on the peripheral surface of the sleeve 302c, and can be cut off. Magnetic carriers are gathered to form a magnetic brush along the normal magnetic field lines emitted from these magnets MG.

There are many configurations of the magnet roller 302d. Here, as shown in FIG. 3, a configuration of a magnet roller having three magnets MG in the sleeve 302c and generating three magnetic poles (magnetic force distribution) will be described.
The magnetic pole of the part (area corresponding to the development nip area A) facing the line connecting the center O-1 of the developing sleeve 302 and the center O-2 of the photosensitive member is referred to as a P1 pole (developing pole). The magnetic poles are referred to as P2 (casing counter pole) and P3 pole (developer regulating member counter pole) in the order of rotation of the developing sleeve 302 indicated by the direction.
The polarity is changed from the P1 pole to the N, S, and S poles, but these poles may have opposite polarities. The P1 pole is a development pole and faces the photoreceptor 1. P2 faces the casing, and P3 faces the developer regulating member.
The developing sleeve 302 and the photosensitive member 1 are not in direct contact with each other in the developing nip region A (see FIG. 1), but are opposed to each other while maintaining a developing gap GP at a constant interval suitable for development.

On the developing sleeve 302, the developer 320 is raised and brought into contact with the photosensitive member 1, so that toner is attached to the electrostatic latent image on the surface of the photosensitive member 1 to be visualized (visualized). )
In the developing device 3, a grounded bias power source is connected to the fixed shaft 302a of the developing sleeve 302 in FIG. 2 (not shown).
The voltage of the power source VP connected to the fixed shaft 302a is applied to the sleeve 302c through a conductive bearing (not shown) and a conductive rotating shaft 302e in FIG. On the other hand, the lowermost conductive support constituting the photoreceptor 1 is grounded.

In the development nip area A shown in FIG. 2, an electric field for moving the toner separated from the carrier to the photosensitive member 1 side is formed, and the sleeve 302 c and the electrostatic latent image formed on the surface of the photosensitive member 1 are formed. The toner is moved toward the photoreceptor 1 side by the potential difference.
The illustrated developing device is an example in which the developing device is combined with an image forming apparatus of a writing method using exposure light L (see FIG. 1).
The charging device 2 uniformly applies negative charges on the photosensitive member 1 and exposes the image portion with the exposure light L in order to reduce the writing amount. A so-called reversal development method is employed in which the latent image is developed with negative polarity toner. This is merely an example, and the polarity of the charged charge placed on the photoreceptor 1 is not a major problem in the development system.

After the development, the P2 pole conveys the developed developer 320 carried on the developing sleeve 302 to the downstream side along with the rotation of the developing sleeve 302 and draws it into the casing 301.
The P2 and P3 poles have the same polarity, and there is no magnetic force to rise between the P2 and P3 poles, so that the ears fall asleep, and the developer 320 that has been drawn around the developing sleeve 302 until then is separated from the developing sleeve 302. The action of “release” works.
The portion corresponding to the P2 to P3 pole on the developing sleeve where the ear is lying (region where the peak of the mountain shape of the magnetic force distribution curve is extremely low compared to other regions) separates the developer 320 from the developing sleeve 302. In FIG. 2, it is indicated by reference numeral 9).

The developer 320 having the toner adhered to the photosensitive member 1 has a lower toner concentration in the developer. Therefore, the developer having the lowered toner concentration does not leave the developing sleeve 302 and again enters the developing nip region A. When transported and subjected to development, there is a problem that a target image density cannot be obtained.
In order to prevent this, in this example, the developer is separated from the developing sleeve 302 in the agent separation region 9 after development. Thereafter, the developer separated from the developing sleeve 302 is sufficiently agitated and mixed in the casing 301 so as to obtain a target toner concentration and toner charge amount.

  Thus, the developer having the target toner concentration and charge amount is supplied to the developer storage space C by the supply chamber conveying member 304. At that time, in order to prevent the developer supplied from the supply chamber conveying member 304 disposed above the developing sleeve 302 from being directly pushed into the developer storage space C, the vehicle overcomes the inflow prevention wall. A measure is taken so that the developer is supplied to the developer storage space C (the flow-in prevention wall 311 is formed in a part of a partition plate 306 constituting a partition portion described later).

  The developer supplied to the storage space C is adjusted to a predetermined thickness by passing through the developer regulating member 303 located immediately downstream of the peak position of the P3 pole, and forms a magnetic brush. It is conveyed to area A. In addition, the P3 pole serves as a transport pole for transporting the developer.

Hereinafter, the arrangement configuration of each member will be described with reference to FIG. 5 showing the internal configuration of the developing device in an assembled state and FIG. 6 showing the disassembled state as necessary.
As shown in FIGS. 2 and 3, the supply chamber conveying member 304 is positioned around the developing sleeve 302 in the direction of 2 o'clock on the clock face with respect to the position of the developing sleeve 302. Has been placed. This position is also on the upstream side of the developer regulating member 303.

  As shown in FIGS. 5 and 6, the supply chamber transfer member 304 has a screw shape with a spiral around the rotation axis. The supply chamber conveying member 304 rotates about a center line O-304 parallel to the center line O-302a of the developing sleeve 302 in the clockwise direction indicated by an arrow, and the back side in the longitudinal direction of the center line O-304. The developer is conveyed while stirring from the side toward the front side as indicated by an arrow 11. That is, the supply chamber conveyance member 304 conveys the developer in the axial direction from the near side to the far side by the rotation of the rotation shaft.

  The collection chamber conveyance member 305 is disposed in the vicinity of the agent separation region 9 at a position around the developing sleeve 302 and in the 4 o'clock direction of the developing sleeve 302. As shown in FIG. 5, the recovery chamber transport member 305 has a screw shape with a spiral around the rotation axis, and a center line O- parallel to the center line O-302a (see FIG. 2) of the developing sleeve 302. 5 is rotated counterclockwise as indicated by an arrow about 305 (see FIG. 2), and is indicated by an arrow 12 in FIG. 5 from the long side in the longitudinal direction of the center line O-305 (see FIG. 2) toward the near side. The developer is transported while stirring. That is, the collection chamber transport member 305 transports the developer from the back side to the front side opposite to the transport direction by the supply chamber transport member 304 by the rotation of the rotation shaft.

The supply chamber transfer member 304 is positioned above the recovery chamber transfer member 305, and the space around the supply chamber transfer member 304 and the space around the recovery chamber transfer member 305 are adjacent to each other in the casing 301. Yes.
As shown in FIG. 5, the front end portions of the supply chamber transport member 304 and the collection chamber transport member 305 are set to be slightly in front of the front end portion of the developing sleeve 302 so as to be in front of the developing sleeve 302. The supply of developer at the side end is ensured.
Further, as shown in FIG. 6 and FIG. 7, a toner which will be described later is set so that the back end portions of the supply chamber transport member 304 and the recovery chamber transport member 305 are located on the back side with respect to the back end portion of the developing sleeve 302. Space for replenishment is secured. The developer regulating member 303 is installed according to the length of the developing sleeve 302.

2 and 3, a partition plate used as a partition between the supply chamber transfer member 304 and the recovery chamber transfer member 305 to shield the space around the supply chamber transfer member 304 and the space around the recovery chamber transfer member 305. 306 is supported inside the casing 301. As shown in FIG. 7, communication ports 307 and 308 are provided at both end portions of the partition plate 306.
In FIG. 5, the developer transported in the direction of arrow 12 by the recovery chamber transport member 305 is cut off along the side wall of the casing 301 at the end in the transport direction, and rises along the side wall. 7), the supply chamber transfer member 304 moves the upper transfer path along the supply chamber transfer member 304 along the arrow 14 (movement in the direction indicated by the arrow 11).
Similarly, the developer conveyed in the direction of the arrow 11 by the supply chamber conveying member 304 is lowered along the side wall via the communication port 308 in order to cut off the path at the side wall of the casing 301 at the end in the conveying direction. Then, the recovery chamber transfer member 305 moves along the arrow 13 to the lower transfer path along the recovery chamber transfer member 305 (moves in the direction indicated by the arrow 12).

2 and 3, the developing device 3 has the following configuration.
A developing sleeve 302 that carries a developer and rotates to visualize the electrostatic latent image formed on the photosensitive member 1 and a center line O-304 parallel to the center line O-302a of the current developing sleeve 302 are centered. And a supply chamber conveying member 304 that conveys the developer while stirring the developer in the longitudinal direction of the center line O-304, and a developer sleeve that is disposed in the vicinity of the agent separation region 9 that separates the developer from the developing sleeve 302. The recovery chamber conveyance that conveys the developer while stirring the developer in a direction opposite to the direction in which the supply chamber conveyance member 304 conveys the developer by rotating around a center line O-305 parallel to the center line O-302 of 302. A partition plate 306 having openings at both ends between the member 305 and between the supply chamber transfer member 304 and the recovery chamber transfer member 305 and shielding the space around the supply chamber transfer member 304 and the space around the recovery chamber transfer member 305; The Eteiru.

In the developing device 3, two conveying members 304 and 305 in the casing 301 constituting a circulation conveying path along arrows 11, 13, 12, and 14 in FIG. As a result, the horizontal (horizontal) size of the developing device can be reduced as compared with the prior art shown in FIG. 11 in which the two agitating and conveying members are arranged in the direction away from the developing sleeve (in the horizontal direction). .
Further, in the developing device 3 that is compact in the horizontal direction, the partition plate 306 partitions the space around the supply chamber transfer member 304 and the space around the collection chamber transfer member 305. As a result, only the developer 320 in which the toner and the carrier are sufficiently agitated and mixed is supplied to the developing sleeve 302 by the supply chamber conveying member 304.
Since the developer whose toner density has decreased immediately after development is merely agitated and conveyed by the collection chamber conveying member 305 and is not immediately supplied to the developing sleeve 302, the developing sleeve 302 has a target charge amount. Only the toner is used for development, and high image quality can be obtained.

On the other hand, toner density management, which is one of developer management in the developing device 3, is performed by toner replenishment control.
The toner supply will be described as follows.
Since the developer 320 (see FIG. 2) in the developing device 3 consumes toner while repeating the developing operation, it is necessary to replenish the toner in the device from the outside of the developing device.
Therefore, in the developing device 3, toner is replenished from the outside through a developer replenishing portion (hereinafter referred to as a replenishing opening) 309 configured with an opening provided in the vicinity of the end on the back side of the developing device 3 in FIG. 6. .
In the replenishment at this portion, the replenished toner is not immediately used for development, but passes through the communication portion 308 (shown as a communication port in FIG. 7) shown in FIG. In FIG. 2, it is supplied to the space in which the collection chamber transfer member 305 is disposed.
The toner supplied to the recovery chamber is agitated by the recovery chamber transport member 305 and is subjected to development at a stable predetermined toner concentration.

In the lower conveyance path in which the collection chamber conveyance member 305 is disposed, only the developer 320 separated from the developing sleeve 302 is collected, and the toner is not supplied to the developing sleeve 302. As a result, the developer having a non-uniform toner concentration that is not sufficiently agitated by the newly replenished toner from the replenishment opening 309 is not provided for development.
The replenished toner is agitated and mixed in the developer 320 having a lowered toner density away from the developing sleeve 302, and the toner density is normalized before being conveyed to the front side of the developing device 3, and is supplied by the supply chamber conveying member 304. The sheet is lifted up to the upper conveyance path, supplied to the developing sleeve 302 while being conveyed to the back side by the supply chamber conveying member 304, and used for development.

As for toner replenishment control, although not shown, a toner concentration sensor provided at the downstream end of the collection chamber transport member 305 in the transport direction at the lower portion of the unit shown in FIG. 5 is used.
The toner concentration sensor can detect the concentration of toner contained in the developer by detecting a change in magnetic permeability, and can determine whether or not new toner needs to be replenished according to the detection result. .

By providing the toner concentration sensor at the downstream end of the collection chamber conveyance member 305 in the conveyance direction, stable carrier concentration detection is possible, that is, as indicated by arrows 11, 13, 12, and 14 in FIG. Since the developer is used for development before being transported to the back side by the supply chamber transport member 304, more developer is returned to the front side by the collection chamber transport member 305, and the developer 320 tends to accumulate on the near side. It is in.
For this reason, since the toner concentration sensor is disposed on the downstream side of the collection chamber conveying member 305, the developer is always filled above the sensor. Therefore, the toner concentration sensor is stably disposed at this position. Carrier concentration can be detected.

  Like the image forming apparatus shown in the figure, for each color of yellow, magenta, cyan, and black, a photosensitive member is arranged in the horizontal direction, and a charging device or a developing device is provided on each photosensitive member to form an electrostatic latent image. In a tandem type color image forming apparatus that obtains a full-color image by sequentially transferring to a transfer sheet after visualizing, developing devices 3K, 3M, and 3Y are respectively applied to the photoconductors 1K, 1M, 1Y, and 1C arranged in the horizontal direction. 3C is provided. For this reason, in order to reduce the size of the image forming apparatus, it is necessary to reduce the interval between the photosensitive members. For this purpose, it is also necessary to reduce the size of each developing device in the horizontal direction (lateral direction).

By using each developing device having the configuration described later, the lateral dimension of each developing device can be made smaller than that of the conventional one shown in FIG. 10, so that the image forming apparatus can be miniaturized.
In addition, as described above, these developing devices 3K, 3M, 3Y, and 3C are configured to include the agent separation region, the agent pumping region, the supply chamber conveyance member, the collection chamber conveyance member, the partition plate, and the like. Toner having a charge amount is used for development, and high image quality can be obtained. In addition, since the deterioration of the toner can be suppressed, it is possible to stably maintain the performance of the developer for a long period of time, and it is possible to provide a developing device having a long life and high durability. Such a benefit is not unique to the tandem full-color image forming apparatus, but can be obtained in a single-color image forming apparatus.

The features of the present embodiment will be described as follows with the image forming apparatus having the above developing device as an object.
A feature of the present embodiment is that a supply chamber transport member corresponding to a developer supply member and a developer recovery member when the configuration is such that the developer is transferred in the antigravity direction using a portion communicating in the vertical direction In accordance with the length of time during which the 304 and the recovery chamber transport member 305 are stopped, the developer left in the communicating portion is loosened to reduce the rotational load on the supply member and the developer recovery member. It is to have done.

In the developing device in this embodiment, the above-described transport members are juxtaposed in the vertical direction, and the developer transported by the recovery chamber transport member 305 is transferred in the antigravity direction toward the supply chamber transport member 304 side. Therefore, as described with reference to FIG. 11, the bulk of the developer increases on the downstream side in the transport direction by the collection chamber transport member 305.
The developer passes from the developer collection chamber to the supply chamber at a position where the bulkiness is high. If each member is stopped in a state where the developer is accumulated in the communication portion, the bulkiness remains high.

When the recovery chamber transport member 305 is restarted in this state, the rotational load becomes large due to the amount of developer accumulated in the recovery chamber transport member 35, and the drive load at the drive source of these members increases. .
As a result, normal developer conveyance is hindered, resulting in insufficient supply of developer to the supply chamber.

  In this embodiment, in order to prevent an increase in the load on each transport member and these drive sources, the time for which each transport member is left standing is counted, and when the time reaches a predetermined value, each member is The developer accumulated in the communicating portion is loosened by driving in a direction opposite to that at the time of developer conveyance for a predetermined time.

FIG. 8 is a block diagram illustrating a configuration of the control unit 100 for performing the above-described developer loosening.
In the figure, the control unit 100 is also used as a control unit that executes an image forming sequence. As a configuration related to the present embodiment, a timer 101 and a temperature / humidity sensor 102 are connected to the input side, and the output side is connected. Are connected to a drive motor 103 used as a drive source for the supply chamber transfer member 304 and the recovery chamber transfer member 305.

  The timer 101 is a member that measures the elapsed time from when the drive motor 103 is stopped and the supply chamber conveyance member 304 and the collection chamber conveyance member 305 are stopped, and the temperature and humidity sensor 102 measures the temperature and humidity in the apparatus. It is a member.

  In the control unit 100, in the direction opposite to the developer conveyance direction for a predetermined time before each of these members is restarted according to the leaving time after the conveyance members 304 and 305 in the supply chamber and the recovery chamber are stopped. Drive. In this embodiment, the driving time in the reverse direction is set to 0.5 seconds with respect to the standing time of 12 hours. That is, the reverse rotation drive of 0.5 seconds is performed when the 12-hour standing time has elapsed.

  The driving time in the reverse direction described above is a value that takes into account factors that affect the developer transportability, such as the rotation speed of the developing sleeve, the outer diameter of the sleeve, or the type of toner, and the development time depends on the developer transport amount. The members attached to the apparatus are made to correspond to values that are not adversely affected.

In this embodiment, the developer moves when the developer is loosened, thereby preventing deformation of the rubber seal member for preventing developer leakage provided at the end of the developing sleeve, and The driving time in the reverse direction described above is set on condition that the developer does not scatter.
As a result, it is possible to prevent deterioration of the seal member disposed at the end portion of the transport member for preventing developer leakage and not impair durability.

  In this embodiment, driving in the reverse direction is performed based on the leaving time of each conveying member, but this prevents an increase in standby time that occurs when reverse driving is performed each time the conveying member is restarted. Is intended. In other words, if each conveyance member is driven in the reverse direction every time it is restarted, it is necessary to wait for the first print time, and to prevent the user from forcibly waiting.

  On the other hand, when the temperature and humidity in the usage environment of the developing device reaches a specified value, the control unit 100 changes the reverse driving start time set based on the above-described leaving time of each conveying member. Specifically, when the temperature in the use environment becomes 10 ° C. or less, the above-described condition of 12 hours, which is the standing time, is shortened to 4 hours and started. .

  As a result, when a factor causing deterioration in transportability such as solidification due to temperature and humidity in the use environment occurs, it is possible to quickly perform the loosening operation, thereby suppressing deterioration in transportability of the developer.

The operation of the control unit 100 as described above will be described with reference to the flowchart shown in FIG.
In FIG. 9, when the detection information from the temperature / humidity sensor 102 is input, it is determined whether or not the temperature is a predetermined temperature (S1), and if it is the predetermined temperature, the leaving time is determined (S2 and S3). .
When it is determined in step S1 that the use environment temperature is 10 ° C. or less, the reverse drive is performed for a predetermined time according to the elapsed time of the leaving time obtained in step S3 (determination result of whether or not 4 hours have elapsed). Whether or not to perform the reverse rotation drive is determined (S3, S4).
When it is determined in step S1 that the use environment temperature is not 10 degrees or less, the inversion time is reversed for a predetermined time according to the elapsed time of the leaving time obtained in step S2 (determination result as to whether 12 hours have elapsed). It is determined whether to perform driving or not to perform reverse driving (S4, S5).

In the above configuration, it is possible to reliably prevent an increase in the rotational load of the conveying member by simply providing a simple component such as a timer and a temperature / humidity sensor. Occurrence of abnormal images due to insufficient supply can be prevented.
Further, since the image forming apparatus main body only needs to be provided with the above-described simple components in the developing device that is frequently replaced, and the increase in the number of parts to be disposed of is about the same as the above-described components, the developer Thus, it is possible to prevent an increase in cost for preventing the conveyance failure.

DESCRIPTION OF SYMBOLS 1 Photoconductor 3 Developing apparatus 100 Control part 101 Timer 102 Temperature / humidity sensor 103 Drive motor 301 Casing 302 Developing sleeve 303 Layer thickness regulation member 304 Supply chamber conveyance member 305 Collection chamber conveyance member

Japanese Patent Laid-Open No. 11-272062

Claims (6)

A rotatable developing sleeve that supplies developer to the electrostatic latent image formed on the electrostatic latent image carrier and a developer sleeve that is arranged in parallel with the axis of the developing sleeve and supplies the developer to the developing sleeve. A rotatable developer supply member, a rotatable developer recovery member that stirs the developer recovered from the developing sleeve, and a space in which the developing sleeve, the developer supply member, and the developer recovery member can be respectively disposed. A developing device comprising at least a casing having an opening that exposes a part of the developing sleeve to the outside and a toner replenishing portion,
The spaces where the developer supply member and the developer recovery member are arranged are partitioned except for a part of the communication portion,
A drive source for driving the developer and the developer recovery member so that the transport direction of the developer in each partitioned space is in the opposite direction;
A control unit capable of switching the drive direction of the drive source,
The control unit has a timer connected to the input side connected to the input side and a drive source connected to the output side connected to the input side. When it is determined that the specified time has elapsed for the supply member and the developer recovery member, before the developer supply member and the developer recovery member are restarted, the drive in the direction opposite to the normal developer transport direction is performed. A developing device that is allowed to perform for a predetermined time.   The drive amount in the reverse direction of the developer supply member and developer recovery agent set by the control unit is at least a seal member provided in the casing to prevent leakage of the developer from within the casing The developing device according to claim 1, wherein the developing device is set to an amount that does not cause any deformation of the posture.   A temperature / humidity sensor is connected to the input side of the control unit, and the control unit changes the drive start timing in the reverse direction when the temperature / humidity in a usage environment exceeds a specified value. The developing device according to claim 1 or 2.   When the temperature and humidity in the usage environment exceed a specified value, the control unit sets the drive start timing in the reverse direction to be shorter than when a specified time based on the standing time measured by the timer has elapsed. The developing device according to claim 3, wherein: At least a developing sleeve for supplying a developer for an electrostatic latent image on the image carrier, a developer supplying member for supplying the developer so as to face the developing sleeve, and agitating and conveying the developer collected after development A process cartridge in which a developer recovery member is stored together,
A process cartridge, wherein the developer supply member and the developer recovery member have the configuration according to claim 1. An image forming apparatus capable of forming images of a plurality of colors,
An image forming apparatus comprising the process cartridge according to claim 5 in an image forming section corresponding to an image forming section of a plurality of colors.

Images