JP2011141367A - Developing apparatus, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing apparatus, process cartridge, and image forming apparatus where stable density detection is performed without being affected by supply toner even when a density sensor is installed on the downstream side of a developing conveying chamber. <P>SOLUTION: This developing apparatus 20 has a doctor blade 25 under a developing roller 22, and circulates a developer in one direction. On the opposite end side of a feeding section 33 of a stirring conveying chamber 27, a toner supply port 30 is disposed on an upstream side in the developer conveying direction rather than a delivery section 31. A projecting shape 36 is formed on the lower wall between the developing conveying chamber 26 and the stirring conveying chamber 27 in the delivery section 31. The density sensor 40 is installed in or near the delivery section on the side of the developing conveying chamber 26. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a developing device using a developer composed of toner and a carrier, a process cartridge using the developing device, and an image forming apparatus such as a copying machine, a printer, a facsimile, or a multifunction machine having at least two functions thereof. is there.

  In the image forming apparatus of the above type, in recent years, it has become the mainstream to employ a two-component developing type developing device composed of toner and carrier. Many developing devices of this type are configured by arranging two screws arranged horizontally as described in FIG. Of these two screws, the first screw located closer to the photosensitive drum supplies the developer to the developer carrying member (developing sleeve) and collects the developer after passing through the developing section. Used for. The second conveying screw is used for mixing and stirring the developer collected from the developing sleeve and the newly supplied developer.

  On the other hand, in recent years, in an image forming apparatus using an electrophotographic system such as a copying machine or a printer, there has been an increasing demand for downsizing the apparatus main body in order to achieve space saving. However, since a plurality of developing devices are used, the size of the developing device is larger than that of a monochrome device. However, it is desired to reduce the size as much as possible.

  In order to meet this demand, Patent Document 1 proposes a developing device in which two conveying screws, which are circulation means for agitating and conveying the developer and circulating in the developing container, are arranged up and down. This developing device includes a developing container containing a developer, and has a developing sleeve as a developer carrying member at an opening facing the photosensitive drum of the developing container. A developing transport chamber and a stirring transport chamber partitioned by a partition are formed vertically on the side opposite to the opening in the developing container. The developing transport chamber and the stirring transport chamber are circulating means. First and second conveying screws are respectively installed. The first conveying screw conveys the developer in the developing and conveying chamber, and the second conveying screw is supplied from the toner supply port into the agitating and conveying chamber and the toner supplied to the upstream side of the second conveying screw and the agitating and conveying chamber. The existing developer is conveyed while stirring to make the toner density of the developer uniform.

  In the vertical agitation type developing device as described above, the development conveyance chamber and the agitation conveyance chamber are arranged vertically above and below, so that the space occupied in the horizontal direction can be small. For example, a plurality of development devices can be arranged horizontally. In a color image forming apparatus such as a tandem system that is mounted in parallel in the direction, advantages such as contributing to downsizing of the apparatus are obtained.

  The flow of the developer in the vertical stirring type developing device will be described. Supply toner accompanying toner consumption is supplied into the device from a toner supply port provided in a part of the stirring conveyance chamber. The replenished toner is agitated and mixed by the second conveying screw together with the existing developer in the agitating and conveying chamber, and the toner concentration of the developer is made uniform. The developer having a uniform toner concentration is dropped and moved from the feeding portion of the agitating and conveying chamber downstream in the developer conveying direction to the developing and conveying chamber, and is fixedly arranged inside while being conveyed by the first conveying screw. It is pumped over the entire length of the developing sleeve by the magnetic pole of the magnetic roll. The amount of the developer that has been pumped up is regulated by the developer regulating member, and the developer that finally adheres to the developing sleeve and does not reach the development area is agitated and conveyed from the delivery section downstream in the developer conveying direction of the developer conveying chamber. Returned to the room. Further, the developer that has adhered to the developing sleeve and has reached the developing area but has not moved to the image carrier is separated from the developing sleeve by the agent separating magnetic pole and returned to the upper agitating and conveying chamber.

  Thus, the agitating / conveying chamber includes a return from the developing / conveying chamber on the upstream side thereof, a return due to separation of the agent from almost the entire length of the developing sleeve, and replenishment of new toner corresponding to the consumption amount. In this case, since it is necessary to sufficiently stir the new toner before it reaches the developing roller, it is generally desirable that the replenishment position is installed on the upstream side of the stirring transport chamber. It has been found that when a new toner is replenished in the middle of conveyance in the agitation conveyance chamber as in the apparatus described in Patent Document 3, the newly replenished toner remains floating above the developer and is difficult to mix. In view of this, it has been proposed that the upstream side of the agitating and conveying chamber in the developer conveying direction is longer than the developing and conveying chamber, and a toner replenishing port for replenishing new toner is provided on the most upstream side.

  By the way, a density sensor for detecting the toner density in the developer is installed in the developing device. The optimum installation condition of the density sensor is that the toner density is uniform and the developer is stably concentrated in the detection area. It is that. The density sensor installation position that satisfies this condition is the most downstream side of the developing conveyance chamber. Since this position is a development transport chamber, the toner concentration in the developer is uniform, and the developer returning to the stirring transport chamber above is gathered.

  As described above, the most downstream side of the developing conveyance chamber is optimal as the position where the density sensor is installed, but at this position, there is a delivery portion for transferring the developer in the developing conveyance chamber to the agitating conveyance chamber. If a toner replenishing port for replenishing new toner is provided on the most upstream side of the conveyance chamber, the toner being conveyed in the agitating conveyance chamber will fall into the development conveyance chamber, and the toner concentration in the developer will become uneven. There was a problem.

  The present invention solves the above-described conventional problems, and a developing device, a process cartridge, and an image capable of obtaining stable density detection without being affected by the replenishing toner even when the density sensor is installed on the downstream side of the developing conveyance chamber. An object is to provide a forming apparatus.

  In order to solve the above-described problems, the present invention provides a developer carrier that is disposed opposite to an image carrier that carries an electrostatic latent image and contains a magnetic field generating means, a toner carrier located below the developer carrier, and a toner And a developer transport chamber having a first transport member that transports the developer comprising the carrier along the direction of the rotation axis while supplying the developer to the developer carrier, and is arranged to face the lower side of the developer carrier. A developer regulating member that regulates the amount of developer carried on the developer carrying member, and a developer separated from the developer carrying member at a position past the image carrying member. A stirring and conveying chamber having a second conveying member that is collected and conveyed in a direction opposite to the first conveying member along the rotation axis direction of the developer carrier, and a density sensor that detects the toner concentration of the developer. And the developing conveyance chamber and the stirring conveyance chamber are partition walls. The agitating and conveying chamber is disposed above the developing and conveying chamber, and a feed-in portion for feeding the developer into the developing and conveying chamber is provided downstream of the agitating and conveying chamber in the developer conveying direction, In the developing device in which a delivery unit for delivering the developer to the agitation transport chamber is provided upstream of the feeding unit of the development transport chamber in the developer transport direction, the developer is provided in the agitation transport chamber more than the delivery unit. A toner replenishing section is provided on the upstream side in the transport direction, and a convex shape is formed on a lower wall between the development transport chamber and the stirring transport chamber in the transfer section, and the density sensor is connected to the development transport chamber side. A developing device is provided which is installed at or near the transfer section.

In the present invention, it is advantageous that the density sensor is installed on the wall surface on the second transport member side of the developing transport chamber side transfer section.
Further, according to the present invention, it is advantageous that the density sensor is installed on a wall surface on the opposite side of the second transfer member of the development transfer chamber side transfer section.

  Furthermore, in the present invention, a substantially cylindrical developing case is disposed between the end of the developer carrying member in the developing transport chamber between the end of the transferring portion and the transferring portion, and the density sensor is substantially cylindrical. It is advantageous if it is installed on the wall surface of the developing case.

  Furthermore, the present invention is to determine whether the convex shape formed on the lower wall between the developing conveyance chamber and the agitation conveyance chamber reaches a straight line connecting the axes of the first conveyance member and the second conveyance member. It is advantageous to set the height to exceed that.

  In order to solve the above-described problems, the present invention provides a process cartridge that is detachably installed on a main body of an image forming apparatus, and the developing device according to any one of claims 1 to 4. A process cartridge is proposed in which the image carrier is integrated.

  Furthermore, in order to solve the above-described problems, the present invention proposes an image forming apparatus comprising the developing device according to any one of claims 1 to 4 and the image carrier.

  In the present invention, a toner replenishing portion is provided on the opposite end side of the feeding portion of the agitating and conveying chamber to the upstream side in the developer conveying direction from the transferring portion, and the transferring portion is provided between the developing conveying chamber and the stirring and conveying chamber. A convex shape is formed on the wall, and since the density sensor is installed at or near the transfer part on the development conveyance chamber side, there is no density fluctuation due to replenishing toner, and the agent in the detection area is stable, The toner concentration in the developer can be appropriately controlled, and a good image can be stably provided.

1 is an overall configuration diagram illustrating an image forming apparatus according to Embodiment 1 of the present invention. It is a block diagram which shows an image creation part. It is sectional drawing which shows a developing device. It is explanatory drawing which shows the flow of the developer in a developing device. FIG. 3 is a cross-sectional explanatory view of a transfer portion of the developing device showing an embodiment of the present invention. FIG. 10 is a cross-sectional explanatory view of a transfer portion of a developing device showing another embodiment of the present invention. It is front explanatory drawing of the image development apparatus which shows other embodiment of this invention. FIG. 8 is a perspective view showing a developing case, a developing roller, and a first conveying screw of the embodiment of FIG. 7. FIG. 8 is a cross-sectional explanatory diagram of the embodiment shown in FIG. 7.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a vertical cross-sectional view showing an example of an electrophotographic image forming apparatus. The image forming apparatus shown here includes first to fourth drum-shaped photoconductors arranged in an apparatus main body 1. And image transfer bodies 2Y, 2M, 2C, and 2K, and an intermediate transfer body configured as an endless intermediate transfer belt 3 that is also disposed in the apparatus main body 1. The intermediate transfer belt 3 is wound around the support rollers 4, 5, 6 and 7 and rotated in the direction of arrow A.

  The intermediate transfer belt 3 is positioned above the image carriers 2Y to 2K, and the lower running side of the intermediate transfer belt 3 is in contact with the peripheral surface of the image carriers 2Y to 2K. It constitutes an example of a transfer material on which toner images of different colors respectively formed on the surface of the carrier can be transferred.

  The configuration in which a toner image is formed on each of the first to fourth image carriers 2Y, 2M, 2C, and 2K and the toner image is transferred to the intermediate transfer belt 3 is substantially different only in the color of the toner image. Since all of them are the same, only a configuration in which a toner image is formed on the first image carrier 2Y and the toner image is transferred to the intermediate transfer belt 3 will be described. The subscripts Y, M, C, and K indicate yellow, magenta, cyan, and black colors, and these subscripts are omitted as necessary.

  Although FIG. 2 omits the suffix “Y”, the image carrier 2 corresponding to yellow and each image forming device for forming a toner image on the surface of the image carrier 2 are enlarged. FIG. The image carrier 2 is rotationally driven in the clockwise direction in FIG. 2, and at this time, the image carrier 2 is charged to a predetermined polarity by a charging device including a charging roller 8 to which a charging voltage is applied. The charged image carrier 2 is irradiated with a light-modulated laser beam L emitted from an optical writing device (not shown), whereby an electrostatic latent image is formed on the image carrier 2. The electrostatic latent image is visualized as a yellow toner image by the developing device 20 described in detail later.

  A primary transfer roller 9 is disposed on the side opposite to the image carrier 2 with the intermediate transfer belt 3 interposed therebetween, and a transfer voltage is applied to the primary transfer roller 9 so that the toner image on the image carrier 2 is changed to an arrow. Primary transfer is performed on the intermediate transfer belt 3 rotating in the A direction. The transfer residual toner adhering to the image carrier 2 after the toner image transfer is removed by the cleaning device 10. Further, the electric charge remaining on the image carrier 2 is removed by a static eliminator (not shown) to prepare for the next image formation.

  In exactly the same manner as described above, a cyan toner image, a magenta toner image, and a black toner image are respectively formed on the second to fourth image carriers 2M, 2C, and 2K shown in FIG. Are sequentially superposed on the intermediate transfer belt 3 to which the yellow toner image has been transferred, and are primarily transferred to form a composite toner image on the intermediate transfer belt 3. The transfer residual toner on each of the image carriers 2M, 2C, 2K after the toner image transfer is removed by the cleaning device 10 is not different from the case of the first image carrier 2Y.

  On the other hand, as shown in FIG. 1, a paper feed cassette 11 containing a recording medium P made of, for example, transfer paper and a paper feed device 13 having a paper feed roller 12 are arranged at the lower part in the apparatus main body 1. As the paper roller 12 rotates, the uppermost recording medium P is sent in the direction of arrow B. The fed recording medium is fed by a registration roller pair 13 between a portion of the intermediate transfer belt 3 wound around the support roller 6 at a predetermined timing and a secondary transfer roller 14 disposed on the intermediate transfer belt 3. The At this time, a predetermined transfer voltage is applied to the secondary transfer roller 14, whereby the composite toner image on the intermediate transfer belt 3 is secondarily transferred to the recording medium P.

  The recording medium P on which the composite toner image has been secondarily transferred is further conveyed upward and passes through the fixing device 15. At this time, the toner image on the recording medium P is fixed by the action of heat and pressure. The recording medium P that has passed through the fixing device 15 is discharged by a paper discharge roller pair 16 to a paper discharge unit 17 at the top of the apparatus main body 1. Further, the transfer residual toner adhering to the intermediate transfer belt 3 after the toner image transfer is removed by the cleaning device 18. 2 is configured as a process cartridge, and can be mounted on a device.

  As shown in FIG. 3, the developing device 20 is filled with a fixed amount (225 g) of a developer in which toner (5.8 μm) mainly composed of a polyester resin and a carrier (35 μm) as magnetic fine particles are uniformly mixed to 7 wt%. The developing case 21 and a developing roller 22 as a developer carrying member that is rotatably supported by the developing case 21 and is disposed in close proximity to the image carrier 2 through an opening formed in the developing case 21. The developing roller 22 includes a developing sleeve 23 that rotates counterclockwise in FIG. 2 and a magnetic roll 24 that is fixed in the sleeve and has five magnetic poles P1 to P5. Yes. FIG. 3 shows the positions where the magnetic forces of the five magnetic poles P1 to P5 are peaked. A doctor blade 25 as a developer restricting member supported by the developing case 21 is disposed close to the lower side of the developing roller 22, and the amount of developer on the developing roller 22 is regulated by the doctor blade 25. The developing device 20 is provided with a developing and conveying chamber 26 obliquely below the developing roller 22 and a stirring and conveying chamber 27 that is substantially horizontal and above the developing and conveying chamber 26. A first transport screw 28 as a developer transport member is disposed in the development transport chamber 26, and a second transport screw 29 as a developer transport member is disposed in the agitation transport chamber 27. The first and second conveying screws 28 and 29 have their axes parallel to the axis of the developing roller 22, and the first conveying screw 28 is adjacent to the entire length of the developing roller 22 in the axial direction. The length of the conveying screw 28 in the axial direction is set to be equal to or slightly longer than the length of the developing roller 22. Similarly, the second conveying screw 29 adjacent to the entire length of the developing roller 22 in the axial direction may be the same length as the first conveying screw 28. However, in this embodiment, the length of the second conveying screw 29 is the first conveying screw. The screw 28 is set to be long. The first and second conveying screws 28 and 29 are rotated at 600 to 800 rpm to convey the developer while stirring, thereby uniformly mixing the toner and the carrier and applying the charge.

FIG. 4 is a development explanatory view showing the flow of the developer in the developing device according to the present invention.
In FIG. 4, a toner concentration sensor (not shown) is provided in the developing device 20. When the sensor detects that the toner concentration is insufficient, it is provided on the upstream side (left end in the figure) of the agitating and conveying chamber 27 in the developer conveying direction. The toner according to the amount of toner consumption is replenished from the toner replenishing port 30 as the toner replenishing portion. The agitating / conveying chamber 27 is provided with a transfer portion 31 through which the developer conveying chamber 26 and the agitating / conveying chamber 27 communicate with each other after the toner supply port 30, and the transfer blade 31 scrapes the doctor blade 25 within the developing and conveying chamber 26. Dropped developer or the like is sent. The developer that has been carried on the developing roller 22 and reached the developing area but has not been developed is returned to the agitating / conveying chamber 27 that has passed the transfer section 31 via a collection guide 32 formed in the developing case 21. Then, the return developer covers almost the entire length of the developing roller 22, and these developers are conveyed to the right in the drawing by the rotation of the second conveying screw 29.

  By being transported while being stirred by the second transport screw 29, the developer in the stirring transport chamber 27 in which the toner density becomes uniform is fed into the developing transport chamber 26 from a feeding portion 33 provided on the downstream side in the transport direction. . Since the agitating / conveying chamber 27 is located above the developing / conveying chamber 26 in the feeding portion 33, the developer is fed by its own weight drop. Note that the positions of the transfer portion 31 and the feeding portion 33 are provided at positions beyond the left end and the right end of the developing roller 22, respectively.

  As described above, the developing device 20 employs a system in which the developer is supplied to the developing roller 22 while being agitated and conveyed by the first conveying screw 28 and is collected by the second conveying screw 29. As described above, the developer accumulation state in the developing and conveying chamber 26 and the agitating and conveying chamber 27 becomes oblique (the amount of developer in the supply screw decreases in the downstream direction). When the developer conveyance amount capability obtained from the diameter, pitch and rotation speed of the first conveyance screw 28 is Wm, and the developer conveyance amount on the developing roller 22 is Ws, the developer is obtained when the relationship between the two becomes Wm> Ws. Are uniformly conveyed onto the developing roller 22. If this condition is not satisfied, the developer is insufficient on the downstream side of the first conveying screw 28, and the developer cannot be supplied to the developing roller 22.

  In this way, the developing device 20 to which the developer is transported replenishes new toner from the toner replenishing port 30 when detecting the toner concentration in the developer and detecting that the concentration has decreased due to toner consumption. The toner density sensor used for this purpose is optimally installed at a location where the toner density is uniform and the developer is stably concentrated in the detection area. The position where the density sensor that satisfies this condition is installed is located on the most downstream side of the developing and conveying chamber 26. At this position, there is a transfer portion for transferring the developer in the developing and conveying chamber 26 to the agitating and conveying chamber 27. If the toner replenishing port 30 for replenishing new toner is provided on the most upstream side of the toner, the toner being conveyed in the agitating and conveying chamber will fall into the developing and conveying chamber 26, resulting in uneven toner density in the developer. I explained earlier that there is a problem.

Therefore, in the present invention, the following measures are taken in order to prevent the toner density non-uniformity on the most downstream side of the developing conveyance chamber 26 and to stabilize the detection accuracy of the toner density sensor 40.
In FIG. 5, the delivery portion 31 of the present invention is formed in a straight line 35 parallel to a straight line S connecting the axial centers of the first transport screw 28 and the second transport screw 29 on the upper side in the longitudinal sectional shape, and the lower side is the first side. The conveying screw 28 and the second conveying screw 29 are curved substantially concentrically, and a pointed convex shape 36 that divides the region between the first conveying screw 28 and the second conveying screw 29 at the approximate center between the two screws 36. Is formed. In addition, the height of the convex shape 36 of the present embodiment is set to a height that reaches the connecting straight line S or protrudes slightly above it. The transfer section 31 is provided with a paddle 34 as shown in FIGS. 4 and 5 as a member for sending the developer in the developing transport chamber 26 to the agitating transport chamber 27. The paddle 34 is connected to the first transport screw 28. It is fixed to the shaft.

  In the transfer section 31 configured in this manner, the developer pushed up by the rotation of the paddle 34 is smoothly fed along the parallel straight line 35 on the upper side, and the new toner supplied from the toner supply port 30 is supplied. Since mixing is performed from above, dispersion of the replenishing toner is promoted. Two or more paddles 34 are arranged on the shaft of the first conveying screw 28 so that the replenishment toner is always dispersed and stirred by the delivery agent.

  In this embodiment, the density sensor 40 for measuring the toner density is installed in the transfer unit 31. The density sensor 40 in the example of FIG. It is provided on the wall surface on the conveying screw 29 side. If the density sensor 40 is installed at such a position, even if the toner falls from the agitating / conveying chamber 27 side, it is difficult to reach the detection region of the sensor, so that it is possible to prevent variations in detection accuracy due to mixing of replenishing toner. Furthermore, the convex shape 36 prevents the developer from being transferred between the screws, and only the developer overflowing above the convex shape 36 moves to the second conveying screw 29. Therefore, the developer is always in the convex shape 36. Therefore, the developer can stably exist in the detection area of the density sensor 40. Therefore, variation in detection accuracy due to bulk fluctuation caused by change in developer conveyance speed and fluidity can be improved at the same time, and toner density can be controlled appropriately.

  FIG. 6 is a cross-sectional view of the transfer unit 31 showing another embodiment of the present invention. The configuration of the density sensor 40 is the same as that of FIG. The density sensor 40 of the present embodiment is installed on the outer wall of the developing conveyance chamber 26 and on the wall surface opposite to the second conveyance screw 29. By providing the density sensor 40 in this manner, even if a small amount of replenishment toner falls to the supply side, the sensor is located on the opposite side, so that it is not easily affected by the replenishment toner. Further, since the density sensor 40 is provided on the side where the developer is pushed upward from the bottom when viewed from the rotation direction of the first conveying screw 28, pressure is easily applied to the developer around the detection unit. As a result, the developer It is possible to suppress variations in sensor output due to random gaps generated therein.

  As described above, the concentration sensor 40 is advantageously provided in the transfer unit 31, but the installation position of the concentration sensor 40 is upstream of the transfer unit 31 in the transfer direction of the first transfer screw 28 and the right end of the transfer unit 31. To the left end of the developing roller 22 may be provided. That is, the density sensor 40 may be provided at a position surrounded by a dotted line on the right side of the transfer unit 31 in FIG. At this position, as shown in FIG. 8, the developing case 21 has a cylindrical case shape 21A corresponding to the first conveying screw 28, and as shown in FIG. 9, the concentration sensor 40 is placed on the wall surface of the case shape 21A. It is installed.

  In this way, even if the density sensor 40 is provided at a position slightly shifted upstream from the delivery unit 31, the replenishment toner is less likely to fall than the convex shape 36, so that there is no change in toner density and the delivery unit. Since it is adjacent to 31, the developer sent to the agitation transport chamber 27 gathers and there is no risk of running out of the agent, and the toner concentration can be controlled stably and accurately.

1 image forming apparatus body (apparatus body),
2 image carrier 20 developing device 22 developing roller (developer carrier),
25 Doctor blade (developer regulating member)
26 Developing transport chamber 27 Stirring transport chamber 28 First transport screw (first transport member)
29 Second conveying screw (second conveying member)
31 delivery section,
36 Convex 40 Density Sensor

Japanese Patent Laid-Open No. 11-174810 JP 2008-26408 A Japanese Patent No. 3950735

Claims (7)

A developer carrying body disposed opposite to an image carrying body carrying an electrostatic latent image and containing magnetic field generating means;
A developing conveyance chamber provided with a first conveying member that is positioned below the developer carrying member and conveys the developer composed of toner and carrier along the rotational axis while supplying the developer carrying member to the developer carrying member;
A developer regulating member disposed to face the lower side of the developer carrying member and regulating the amount of developer carried on the developer carrying member;
At a position past the image carrier, the developer separated from the developer carrier is collected and conveyed in the direction opposite to the first conveying member along the rotation axis direction of the developer carrier. An agitating and conveying chamber provided with a second conveying member;
A density sensor that detects the toner density of the developer;
The developing and conveying chamber and the agitating and conveying chamber are partitioned by a partition, and the agitating and conveying chamber is disposed above the developing and conveying chamber,
A feeding portion for feeding the developer into the developing conveyance chamber is provided on the downstream side in the developer conveyance direction of the stirring conveyance chamber, and the developer is supplied to the stirring conveyance chamber on the upstream side in the developer conveyance direction from the feeding portion of the development conveyance chamber. In a developing device provided with a delivery section that delivers
In the agitating and conveying chamber, a toner replenishing portion is provided upstream of the delivery portion in the developer conveying direction,
A convex shape is formed on a lower wall between the developing conveyance chamber and the agitation conveyance chamber in the transfer section,
2. A developing apparatus according to claim 1, wherein the density sensor is installed at or near the transfer section on the developing transport chamber side.   The developing device according to claim 1, wherein the density sensor is installed on a wall surface on the second transport member side of the development transport chamber side transfer section.   The developing device according to claim 1, wherein the density sensor is installed on a wall surface on the opposite side of the second transport member of the development transport chamber side transfer section.   2. The developing device according to claim 1, wherein a substantially cylindrical developing case is disposed between an end portion of the developer carrying member in the developing transport chamber and between the delivery portion, and the density sensor is substantially A developing device, wherein the developing device is installed on a wall surface of a cylindrical developing case.   5. The developing device according to claim 1, wherein a convex shape formed on a lower wall between the development conveyance chamber and the agitation conveyance chamber is formed by the first conveyance member and the second conveyance. 5. A developing device characterized in that a height reaching or exceeding a straight line connecting the axis of the member is set. A process cartridge that is detachably installed on the main body of the image forming apparatus,
6. A process cartridge, wherein the developing device according to claim 1 and the image carrier are integrated.   An image forming apparatus comprising the developing device according to claim 1 and the image carrier.

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