JP5515892B2 - Development device - Google Patents

Description

  The present invention relates to a developing device in electrophotography and an image forming apparatus including the developing device, and more particularly to a developer agitating and conveying mechanism.

  In copying machines, printers, facsimile machines, and these multifunction devices, an electrostatic latent image is formed on a photosensitive drum, the electrostatic latent image on the photosensitive drum is developed with toner, and a toner image is formed on the photosensitive drum. An image forming apparatus that forms, superimposes the paper on the toner image, transfers the toner image onto the paper by applying an electric field from the back of the paper, fixes the toner image on the paper by heating and pressurizing the paper, and obtains a recording output It has been known.

As a developer used for such development, there is a two-component developer obtained by mixing a magnetic or non-magnetic toner and a carrier containing a magnetic material or formed of a magnetic material.
In this two-component developer, the toner is charged by the frictional charging action of the toner and the carrier generated during the stirring and mixing, and the developer thus charged is applied to the electrostatic latent image on the photosensitive drum (image carrier). Electrostatic adsorption.
As a developing device for this purpose, a developer carrier that supplies a developer toward the electrostatic latent image on the photosensitive drum by causing the developer to rise on the peripheral surface by magnetic force, and agitating the developer carrier A configuration is known that includes a first agitating and conveying member that supplies the mixed developer, and a second agitating and conveying member that agitates and mixes the two-component developer and the replenishment toner and conveys them to the first agitating and conveying member. In such a stirring and conveying member, a screw formed in a spiral shape on the rotating shaft is usually used.
Further, when the electrostatic latent image on the photosensitive drum is developed to form a toner image on the photosensitive drum, the developer that has consumed the toner is collected by the developing device for reuse. It is configured.

The collected developer consumes toner. If it is used as it is, the toner concentration contained in the developer is low and the image density is lowered. Therefore, the collected developer is appropriately replenished with toner from the outside of the developing device. There is a need to.
Replenishment of toner is performed according to the result of detecting the developer concentration by a detection means such as a toner concentration sensor. In the case of the developing device described above, the developer is replenished from above the second stirring and conveying member so as to be poured into the developer.
The replenished toner is agitated and mixed with the developer by the second agitating and conveying member, and is conveyed toward the first agitating and conveying member.

However, if the replenished toner is not sufficiently dispersed in the developer, the toner density on the developer carrying member becomes uneven and the toner density on the developer carrier overshoots from the target toner density. As a result, image quality problems such as image density unevenness, background contamination, and toner scattering may occur.
Therefore, as a configuration for dispersing the replenishment toner in the developer, Patent Document 1 uses a paddle in the vicinity of the surface of the two-component developer to which the toner is replenished to pump the replenishment toner and the two-component developer. The replenishment toner is dispersed in the two-component developer while dropping and repeating the toner lump.
In Patent Document 2, a magnetic roller is embedded in the two-component developer at a position below the toner supply location, and the replenishing toner is mixed with the two-component developer by the stirring and mixing action of a rotating magnetic brush generated around the magnet roller. ing.

In recent years, the image forming apparatus is required to be downsized in the apparatus main body, and accordingly, each internal component in the apparatus and each process cartridge to be used are also downsized.
Similarly, the developing device is also miniaturized, so that the capacity of the developer that can be accommodated in the developing device is smaller than that of a conventional large machine. However, the amount of toner consumed is the same as that of conventional large machines.
Therefore, since the amount of the replenished toner must be increased with respect to the developer capacity, sufficient stirring and mixing of the replenished toner is further required.
However, when the developing device is downsized, the lengths of the first agitation transport member and the second agitation transport member need to be shortened, so that the agitation efficiency is lowered. It is difficult to sufficiently stir and mix.

  In the configuration of the conventional example, in the downsized developing device, the replenishment toner is not sufficiently dispersed in the developer, and the developer is supplied to the developing roller while the toner concentration is unevenly distributed. This causes a problem that the toner density on the developer carrier overshoots from the target toner density as described above.

  The present invention has been made in view of the above problems, and even in a developing device with a small developer capacity, the stirring function is improved, and the toner concentration on the developer carrying member exceeds the target toner concentration. It is an object of the present invention to provide an agitating / conveying member that can reduce the amount of chute, a developing device that does not cause uneven development by using the agitating / conveying member, and an image forming apparatus including the developing device.

In order to achieve the above object, the present invention provides an agitating and conveying member that rotates about a rotation axis and agitates and conveys a developer composed of toner and a carrier to the downstream side in the rotation axis direction. Includes a first partition member provided on the rotation shaft for conveying the developer downstream in the rotation axis direction, and a developer provided on the rotation shaft for conveying the developer upstream in the rotation axis direction. A second partition member is provided, the first partition member and the second partition member are disposed to face each other , and the first partition member and the distal end portions of the second partition member and the A stirring / conveying member characterized in that a gap is provided between the rotating shaft and the developer is movable from the gap .

  According to the present invention, by increasing the frequency of contact between the toner and the developer, it is possible to improve the dispersibility of the replenished toner in the developer. Also in the apparatus, the stirring function can be improved, and the stirring and conveying member capable of reducing the amount of overshoot from the target toner density of the toner density on the developer carrier, and the developing device using the stirring and conveying member, A process cartridge and an image forming apparatus including the process cartridge can be provided.

The front view of the stirring conveyance member in embodiment of this invention. The front view of the stirring conveyance member in other embodiment of this invention. The perspective view of the stirring conveyance member of embodiment of this invention. The side view of the stirring conveyance member of embodiment of this invention. 1 is a schematic view of an image forming apparatus using a stirring and conveying member of the present invention. FIG. 2 is a schematic view of a developing device using the stirring and conveying member of the present invention. The comparative example of a stirring conveyance member. Explanatory drawing (1) of an effect | action with respect to the developer in embodiment of this invention. Explanatory drawing (2) of an effect | action with respect to the developer in embodiment of this invention. The other comparative example of a stirring conveyance member. 6 is a graph showing a change in toner density with respect to agitation time in each agitation transport member example. 6 is a graph for explaining a relationship between each example of the agitating / conveying member and an overshoot from a target toner concentration.

Hereinafter, an embodiment of an electrophotographic color printer (hereinafter simply referred to as “printer”) will be described as an image forming apparatus to which the stirring and conveying member of the present invention is applied. The image forming unit will be described as a process cartridge.
First, the basic configuration of the printer will be described.
FIG. 5 is a schematic configuration diagram of the printer. The printer 100 includes four process cartridges 6Y, 6M, 6C, and 6K for generating toner images of yellow, magenta, cyan, and black (hereinafter referred to as Y 1, M 2, C 3, and K). These use different colors of Y 1, M 2, C 3, and K toners as image forming substances, but other than that, they have the same configuration and are replaced when the lifetime is reached.
Taking a process cartridge 6Y for generating a Y toner image as an example, as shown in FIG. 6, a drum-shaped photoreceptor 1Y, a drum cleaning device 2Y, a charge eliminating device (not shown), a charging device 4Y, a developing device 5Y, and the like. It has.
The process cartridge 6Y can be attached to and detached from the main body of the printer 100 so that consumable parts can be replaced at a time.

The charging device 4Y uniformly charges the surface of the photoreceptor 1Y that is rotated clockwise in the drawing by a driving unit (not shown).
The uniformly charged surface of the photoreceptor 1Y is exposed and scanned by the laser beam L and carries a Y electrostatic latent image.
The electrostatic latent image for Y is developed into a Y toner image by the developing device 5Y using Y toner, and the toner image thus developed is intermediately transferred onto the intermediate transfer belt 8.
Next, the toner remaining on the surface of the photoreceptor 1Y after the intermediate transfer process is removed by cleaning by the drum cleaning device 2Y.
Next, the residual charge remaining on the photoreceptor 1Y after cleaning is neutralized by a static eliminator, and this neutralization initializes the surface of the photoreceptor 1Y to prepare for the next image formation.

In the other process cartridges 6M, 6C, and 6K, M, C, and K toner images are similarly formed on the photoreceptors 1M, 1C, and 1K, and all of them are intermediately transferred onto the intermediate transfer belt 8.
In FIG. 5, the exposure device 7 is disposed below the process cartridges 6Y, 6M, 6C and 6K.
The exposure device 7 serving as a latent image forming means irradiates the respective photosensitive members in the process cartridges 6Y, 6M, 6C, and 6K with a laser beam L emitted based on the image information.
By this exposure, electrostatic latent images for Y, M, C, and K are formed on the photoreceptors 1Y, 1M, 1C, and 1K.
The exposure device 7 scans the laser light L emitted from the light source based on the image information with a polygon mirror that is rotationally driven by a motor, and passes the photoreceptors 1Y 1M 1C 1C through a plurality of optical lenses and mirrors. It irradiates on 1K.

On the lower side of the exposure apparatus 7 in the figure, paper supply means having a paper storage cassette 26, a paper supply roller 27 incorporated therein, a registration roller pair 28, and the like are disposed.
The paper storage cassette 26 stores a plurality of transfer papers P as recording bodies, and a paper feed roller 27 is in contact with the uppermost transfer paper P.
When the paper feeding roller 27 is rotated counterclockwise in the drawing by a driving means (not shown), the uppermost transfer paper P is fed toward the rollers of the registration roller pair 28.
The registration roller pair 28 rotationally drives both rollers to sandwich the transfer paper P, but temporarily stops rotating immediately after sandwiching. Then, the transfer paper P is sent out toward a later-described secondary transfer nip at an appropriate timing.
In the sheet feeding unit having such a configuration, a conveying unit is configured by a combination of the sheet feeding roller 27 and the registration roller pair 28 corresponding to the timing roller.
This transport means transports the transfer paper P from a paper storage cassette 26 serving as a storage means to a secondary transfer nip described later.

Above the process cartridges 6Y, 6M, 6C, and 6K in the figure, an intermediate transfer unit 15 that moves the endlessly the intermediate transfer belt 8 as an intermediate transfer member while stretching is disposed.
In addition to the intermediate transfer belt 8, the intermediate transfer unit 15 includes four primary transfer bias rollers 9Y, 9M, 9C, and 9K, a cleaning device 10, and the like.
A secondary transfer backup roller 12, a cleaning backup roller 13, a tension roller 14 and the like are also provided.
The intermediate transfer belt 8 is endlessly moved in the counterclockwise direction in the figure by the rotational drive of at least one of the rollers while being stretched around these three rollers.

The primary transfer bias rollers 9Y, 9M, 9C, and 9K sandwich the intermediate transfer belt 8 that is moved endlessly in this manner from the photoreceptors 1Y, 1M, 1C, and 1K to form primary transfer nips, respectively. Yes.
By these primary transfer bias rollers 9Y, 9M, 9C, and 9K, a transfer bias having a polarity opposite to that of toner (for example, plus) is applied to the back surface (loop inner peripheral surface) of the intermediate transfer belt 8.
All the rollers except the primary transfer bias rollers 9Y, 9M, 9C, and 9K are electrically grounded.
The intermediate transfer belt 8 passes through the primary transfer nips for Y 1, M 2, C 3, and K sequentially along with the endless movement thereof, and Y 1, M 2, C 3 on the photoreceptors 1Y 1M 1C 1K , K The toner images are superimposed and primarily transferred.
As a result, a four-color superimposed toner image (hereinafter referred to as “four-color toner image”) is formed on the intermediate transfer belt 8.

The secondary transfer backup roller 12 sandwiches the intermediate transfer belt 8 between the secondary transfer roller 19 and forms a secondary transfer nip.
The four-color toner image formed on the intermediate transfer belt 8 is transferred to the transfer paper P at the secondary transfer nip.
Untransferred toner that has not been transferred onto the transfer paper P adheres to the intermediate transfer belt 8 after passing through the secondary transfer nip. This is cleaned by the cleaning device 10.
In the secondary transfer nip, the transfer paper P is sandwiched between the intermediate transfer belt 8 and the secondary transfer roller 19 whose surfaces move in the forward direction, and is conveyed in the opposite direction to the registration roller pair 28 side. .
When the transfer paper P sent out from the secondary transfer nip passes between rollers of the fixing device 20, the four-color toner image transferred to the surface is fixed by heat or pressure.
Thereafter, the transfer paper P is discharged out of the apparatus through a pair of paper discharge rollers 29.

A stack unit 30 is formed on the upper surface of the printer body, and the transfer paper P discharged outside the apparatus by the discharge roller pair 29 is sequentially stacked on the stack unit 30.
A bottle container 31 is provided on the lower side of the stack unit 30 to store toner bottles 32Y, 32M, 32C, and 32K for each color.

FIG. 6 is a sectional view showing the embodiment of the developing device of the present invention as seen from the side.
Each of the developing devices 5Y, 5M, 5C, and 5K according to the present embodiment has a developing container that contains a two-component developer containing toner and a carrier, and stirs and conveys the two-component developer in the developing container. Meanwhile, the toner of the two-component developer is frictionally charged, and the charged toner is attached to the outer surface of the developing rollers 51Y, 51M, 51C, and 51K, and the developing rollers 51Y, 51M, 51C, and 51K and the photosensitive drum 1Y. , 1M, 1C, and 1K, and the electrostatic latent images on the photosensitive drums 1Y, 1M, 1C, and 1K are developed with the charged toner.
Since the developing devices 5Y, 5M, 5C, and 5K have the same configuration, the developing device 5Y will be described below as an example.

At the bottom of the developing container 40Y of the developing device 5Y, first and second developer paths 54Ya and 54Yb are arranged in parallel along the longitudinal direction of the photosensitive drum 1Y, and the developer paths 54Ya and 54Yb are arranged in parallel. Partitioned by a partition wall 60Y, both end portions of the developer paths 54Ya and 54Yb are connected via respective openings, and the toner supply path 16 is provided above the second developer path 54Yb.
The first and second developer paths 54Ya and 54Yb are provided with first and second screw shafts 55Ya and 55Yb in the longitudinal direction, respectively. The first and second screw shafts 55Ya and 55Yb Is provided with a spiral blade 55Y on the outer periphery of the rotating shaft thereof. Therefore, when the first and second screw shafts 55Ya and 55Yb rotate, the developer is transported along the developer paths 54Ya and 54Yb by the spiral blade 55Y.

Here, when the two-component developer obtained by mixing the toner and the carrier is accommodated in the first and second developer paths 54Ya and 54Yb and the first and second screw shafts 55Ya and 55Yb are rotated, the two-component developer is developed. The first and second developer are repeatedly circulated and conveyed in the circulation conveyance path of the second developer path 54Yb → the opening → the first developer path 54Ya → the opening → the second second developer path 54Yb. The rotation direction of the screw shafts 55Ya and 55Yb and the spiral direction of the spiral blade 55Y are set.
Then, the toner of the two-component developer is frictionally charged with a polarity opposite to that of the electrostatic latent image on the surface of the photosensitive drum 4 in such a circulating conveyance process, and a developing roller disposed above the first developer path 54Ya. 51Y is drawn from the opening 59Y, adheres to the outer peripheral surface of the developing roller 51Y, is transported to the developing area D, adheres to the electrostatic latent image on the photosensitive drum 1Y, and develops the electrostatic latent image. .

The developing roller 51Y has a rod-like multi-pole magnetized magnet fixed thereto, and a non-magnetic body (aluminum alloy, stainless steel, etc.) sleeve is rotatably supported around the multi-pole magnetized magnet. While rotating, the two-component developer is attracted and carried on the outer periphery of the sleeve by the magnetic force of the magnet.
As the sleeve rotates, the layer thickness regulating member 52Y regulates the layer thickness of the two-component developer on the outer periphery of the sleeve, and then the two-component developer layer on the outer periphery of the sleeve moves to the developing region D between the sleeve and the photosensitive drum 1Y. It is conveyed.

On the other hand, as shown in FIG. 6, the developing container 40Y is provided with a toner density sensor 56Y that detects the toner density in the developing container 40Y.
The toner concentration sensor 56Y is a magnetic permeability sensor, and detects the magnetic permeability by contacting the two-component developer conveyed in the developing container 40Y. The ratio of the toner to the carrier is obtained from the detected magnetic permeability.
For example, when the carrier amount in the two-component developer facing the toner concentration sensor 56Y is small, it is detected that the toner concentration is high, and conversely, when the carrier amount is large, it is detected that the toner concentration is low. The detection signal of the toner concentration sensor 56Y is output to the control device 57Y, and the drive motor 41Y is driven by the control device 57Y based on this detection signal, so that the toner is appropriately replenished in the developing container 40Y.

When the development of the electrostatic latent image is repeated and the toner of the two-component developer is consumed, the toner density decreases, so that the toner is supplied from the toner cartridge 72Y into the developing container 40Y through the supply port 58Y.
The toner is conveyed in the second developer path 54Yb while being agitated and mixed with the two-component developer in the second developer path 54Yb, and is conveyed from the opening at the end to the first developer path 54Ya. Then, it is repeatedly circulated and conveyed along the circulation conveyance path described above. As a result, the toner concentration of the two-component developer is maintained at an appropriate concentration.

In this embodiment, as shown in FIGS. 1 and 2, two partition members are included in one pitch of the spiral blade member 55Y near the downstream portion of the second screw shaft 55Yb in the developer conveying direction (P). 101 and 102 are attached to the second screw shaft 55Yb.
Among them, the first partition member 101 is rotated in the same manner as the spiral blade 55Y of the second screw shaft 55Yb so that the developer is transported in the developer transport direction P (P direction in FIG. 1). The second partition member 102 is disposed opposite to the first partition member 101 so as to transport the developer in the direction opposite to the developer transport direction P by rotating.
Further, as shown in FIGS. 3 and 4, the first and second partition members 101 and 102 have rear portions 101b and 102b attached to the second screw shaft 55Yb as viewed from the rotation direction, and tip portions 101a, 102a is formed in the shape spaced apart from the second screw shaft 55Yb.
Further, the tip portions 101a and 102a are provided so as to contact each other as shown in FIG. 1 or close to each other as shown in FIG.
Therefore, as shown in FIGS. 1 and 2, a gap 103 is formed in the vicinity of the inside of the tip end portions 101 a and 102 of the partition members 101 and 102 so that the developer can pass through the rotation of the partition members 101 and 102. It is formed.
As described above, the second screw shaft 55Yb, the spiral blade member 55Y attached to the outer periphery of the rotation shaft, and the partition members 101 and 102 constitute an agitating and conveying member for agitating and conveying the developer. The

With respect to the stirring and conveying member, perspective views when the rotation shaft rotates by 90 degrees are shown in FIG. 3 in order (1) to (4). When rotated 90 degrees from FIG. 3 (4), it returns to FIG. 3 (1).
3 (1) to 3 (4) are schematic views (from the A direction) when the second partition member 102 is viewed in the direction parallel to the rotation axis of the second screw shaft 55Yb and toward the developer transport direction. FIGS. 4 (1) to (4) show the schematic views) corresponding to FIGS. 3 (1) to (4), respectively.
Furthermore, the schematic diagram (schematic diagram seen from B direction) when it sees from the direction perpendicular | vertical to this rotating shaft is shown in FIG.
Here, the regions divided by the partition members 101 and 102 are referred to as an upstream region 105 and a downstream region 104, respectively, along the developer conveyance direction, as shown in FIG.

As shown in FIG. 1, when the toner (T) is replenished on the surface of the developer and the second screw shaft 55Yb rotates in the S direction, the spiral blade member 55Y rotates and the partition members 101 and 102 are also illustrated. 3 Rotate as shown in (1) to (4).
Among these, as shown in FIG. 1 or FIG. 2, the first partition member 101 stirs the toner and developer in the downstream region 104 in the developer transport direction P in the same manner as the spiral blade member 55Y. Convey along.
On the other hand, the second partition member 102 acts to send the toner and developer in the upstream region 105 in the upstream direction with respect to the developer transport direction P, contrary to the first partition member 101.
On the other hand, the replenishment toner and the developer in the developer upstream region 105 in FIG. 1 receive a force to be sent in the developer transport direction P as a whole by the spiral blade member 55Y.

Since the replenishment toner and the developer are given a conveying force by the stirring and conveying member configured as described above, that is, the spiral blade member 55Y and the partition members 101 and 102, they are subjected to the following actions.
(1) First, when the partition members 101 and 102 rotate with the rotation of the second screw shaft 55Yb, the replenishment toner and developer in the upstream region 105 and the downstream region 104 are transferred by the partition members 101 and 102. As indicated by the arrows in FIG. 8, both receive the force of dispersing in the longitudinal direction of the second screw shaft 55Yb, and the supplied toner and developer are sufficiently dispersed and mixed.

(2) Further, when the partition members 101 and 102 rotate with the rotation of the second screw shaft 55Yb, the replenishment toner and developer in the region sandwiched between the partition members 101 and 102 are transferred to the partition members 101 and 102. 102 receives a force in the direction of the arrow in FIG. 9 (that is, a “holding force” of toner or developer).
As described above, the partition members 101 and 102 can give the toner or developer a force in a direction perpendicular to the traveling direction of the developer (“holding force”), and the toner or developer held in the partition member. Can contact a larger amount of developer as compared with the case without a partition member, so that the replenished toner and developer can be sufficiently dispersed and mixed.
Further, since the gap 103 is formed in the partition members 101 and 102, the toner and the developer are not held in the partition members 101 and 102 but are accompanied by the rotation of the second screw shaft 55Yb. Then, it moves in the direction of the arrow (white arrow) pointing upward in FIG. 9 and passes through the gap 103.
In other words, there is a possibility that toner and developer may stay in the partition members 101 and 102 when they are held, but by providing the gap 103, it is possible to pass through the gap 103. Such stagnation can be prevented, and it is possible to cause an action of mixing the replenishing toner while being submerged in the developer without stagnation.

Such “holding” action will be described below in comparison with a comparative example.
As a comparative example, the lengths of the openings in the direction parallel to the rotation axis of the first partition member 101 and the second partition member 102 are equal, that is, the opening length a at the front end of the partition member = open length at the rear end of the partition member FIG. 10 shows the case of b.
In this comparative example, it is impossible to apply a force perpendicular to the developing direction of the developer indicated by the downward arrow in FIG. 9 as in the present invention, and it is not possible to hold replenishment toner or developer.
On the other hand, when the first partition member 101 and the second partition member 102 are provided so that the lengths a and b of the openings shown in FIG. 9 are different, that is, a <b, as shown in FIG. As the first partition member 101 and the second partition member 102 rotate, the replenished toner and developer are dispersed in the longitudinal direction of the second screw shaft 55Yb. By generating a force for holding the agent and causing the replenishment toner to be submerged in the developer, an effect of dispersing the replenishment toner is generated, so that the replenishment toner can be more effectively dispersed in the developer.

As described above, the replenishment toner and developer in the upstream region 105 are subjected to compression force by the second partition member 102 and the spiral blade member 55Y as shown in FIG. As a result, the replenishment toner can be taken into the developer as compared with the case where there is no partition member.
Further, when the partition member rotates as shown in FIGS. 3A to 3B, the developer enters the gap 103. As a result, the replenishment toner comes into contact with the developer more frequently than when there is no partition member, and the replenishment toner can be taken into the developer.
When the partition member is rotated as shown in FIGS. 3 (2) to 3 (3) and further from FIGS. 3 (3) to (4), the first partition member 101 is positively mixed with the replenishing toner and the developer. The second partition member 102 disperses the replenishment toner in the longitudinal direction of the rotating shaft by sending the replenishment toner and the developer to the upstream side in the developer conveyance direction while mixing the replenishment toner and the developer. Can do.

  Thus, according to the present invention, the first partition member 101 and the second partition member 102 are provided, and the partition member rotates in accordance with the rotation of the second screw shaft 55Yb. There is an action of dispersing in the longitudinal direction of the screw shaft 55Yb and an action of causing the partition members 101, 102 to hold the replenishment toner and the developer and dispersing the replenishment toner by letting the replenishment toner into the developer. The replenishment toner can be more effectively dispersed in the developer, and the replenishment toner can be conveyed while sufficiently stirring in the longitudinal direction of the rotating shaft.

Actually, according to the present invention, the partition members 101 and 102 shown above are attached to the downstream side of the developer conveying direction of the second screw shaft 55Yb, and as a comparative example, as shown in FIG. Three types of stirring and conveying members were prepared, one having 106 attached in parallel to the second screw shaft 55Yb and the other having nothing attached to the second screw shaft 55Yb, and their effects were compared. Here, the paddle 106 is a member attached to the second screw shaft 55Yb as shown in FIG. 7 in one pitch of the spiral blade member 55Y. Moreover, the case where nothing is attached is the case where nothing is attached between one pitch of the spiral blade member 55Y.
FIG. 8 shows the result of setting the agitating / conveying member in the developing container, putting the developer into the developing container, replenishing the toner therein, and measuring the toner density on the developing roller 51Y simultaneously with the agitation.
The measurement was performed by applying a laser beam to the developer on the developing sleeve and measuring the diffused light using a light receiving element.

FIG. 11 shows a graph of the change in toner concentration with the stirring time.
Here, attention is focused on the peak when the stirring time is 2 seconds.
As shown in FIG. 11, the toner density (for example, the toner density after 30 seconds) when the fluctuation of the toner density is the target toner density (target toner density) is 7.0 wt. On the other hand, when the paddle 106 is attached in parallel to the screw shaft and when nothing is attached to the screw shaft, the toner concentration at the stirring time of 2 seconds, which is the peak of the toner concentration, is All were 7.4 wt%. On the other hand, in the case of the present Example, it became 7.2 wt%.
Here, FIG. 12 shows the result of calculating the difference between the peak value and the target toner density. The difference between the peak value and the target toner density is called an overshoot amount from the target toner density.
When the paddle 106 is attached in parallel to the screw shaft and when nothing is attached to the screw shaft, the amount of overshoot from the target toner concentration is 0.4 wt%. When the members 101 and 102 are provided, the overshoot amount is 0.2 wt%, and in the present invention, the result that the overshoot amount is decreased by 0.2 wt% was obtained.

  That is, when stirring is performed using the partition members 101 and 102, the amount of overshoot from the target toner density is lower than when the simple paddle 106 is used for the stirring member or when nothing is attached. This indicates that the effect of dispersing the replenishment toner in the longitudinal direction of the screw shaft is high.

  As described above, according to the present invention, by attaching the two partition members to the rotating screw shaft, the toner at the time of replenishing toner can be reduced in the longitudinal direction of the rotating shaft even in a small-sized developing device with a small developer capacity. The stirring member which can be disperse | distributed to can be provided.

In the above embodiment, the second stirring and conveying member in which the partition members 101 and 102 are provided on the second screw shaft 55Yb has been described. However, the partition members 101 and 102 are similarly provided on the first screw shaft 55Ya. By configuring the first agitating and conveying member, a more sufficient agitating and conveying effect can be obtained also for the first agitating and conveying member.
In the above embodiment, the first and second partition members are provided as one set within one pitch of the spiral blade member (spiral member), and such a set of partition members is provided. A plurality of sets can be provided along the longitudinal direction of the screw shaft. In this case, the position of the tip of the partition member of each set is rotated along the locus of the spiral blade member (spiral member). Can be arranged differently. By arranging in this way, it is possible to obtain a further stirring and diffusion effect.

1Y Photosensitive drum
5Y Developer
6Y process cartridge
40Y developer container
51Y Development roller
54 Ya First developer path
54Yb Second developer path
55Y Spiral blade member
55 Ya 1st screw shaft
55Yb 2nd screw shaft
56Y toner density sensor
72Y toner cartridge
101 First partition member
102 Second partition member
103 Gap P Developer transport direction S Screw shaft rotation direction

JP 2008-145875 A JP 2001-188408 A

Claims (7)

A stirring and conveying member that rotates about a rotation axis and stirs and conveys a developer composed of toner and a carrier to the downstream side in the rotation axis direction, and the stirring and conveying member includes the developer provided on the rotation shaft; A first partition member that conveys the developer downstream in the rotation axis direction; and a second partition member that is provided on the rotation shaft and conveys the developer upstream in the rotation axis direction. The partition member and the second partition member are disposed to face each other , and a gap is provided between the first partition member and the distal end portion of the second partition member and the rotation shaft, A stirring and conveying member, wherein the developer is movable from a gap . 2. The stirring and conveying member according to claim 1, wherein the first partition member and the second partition member are arranged such that the tip portions thereof are joined to or close to each other. Element. 3. The stirring and conveying member according to claim 1, wherein the stirring and conveying member includes a spiral member for stirring and conveying the developer to the downstream side in the rotation axis direction. The stirring and conveying member , wherein one partition member and the second partition member are disposed within one pitch of the spiral member. The stirring and conveying member according to any one of claims 1 to 3, wherein the first partition member and the second partition member are a set, and a plurality of the sets are arranged in a longitudinal direction of the rotation shaft. stirring and conveying member, wherein are. A developing device using the stirring and conveying member according to claim 1. A process cartridge using the stirring and conveying member according to claim 1. An image forming apparatus comprising the developing device according to claim 5 or the process cartridge according to claim 6.

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