JP4708079B2 - Developing device, image forming apparatus, and process cartridge - Google Patents

Description

  The present invention relates to a developing device used for image formation by an electrostatic copying process such as a copying machine, a facsimile machine, and a printer, and also relates to an image forming device and a process cartridge using the developing device.

In recent years, office automation and colorization have further progressed in offices, and in addition to copying originals consisting only of conventional characters, originals including graphs created with a personal computer are output by a printer and used as presentation materials. Opportunities to copy sheets are increasing. Printer output images are mostly solid images, line images, and halftone images. Accordingly, market demands for image quality are changing, and demands for high reliability and the like are further increasing.
Developers used in electrophotographic systems such as electrophotography, electrostatic recording, and electrostatic printing are, for example, an image carrier (typically a photoreceptor) on which an electrostatic latent image is formed in the developing process. Then, the toner is transferred from the photosensitive member to a transfer medium such as transfer paper in the transfer process, and then fixed on the paper surface in the fixing process. At that time, as a developer for developing the electrostatic latent image formed on the image carrier, a two-component developer composed of a carrier and a toner, and a one-component system composed of only a toner without requiring a carrier. Developers (magnetic toner, non-magnetic toner) are known. In the two-component developer, the developer deteriorates due to the toner particles adhering to the carrier surface, and the toner concentration in the developer decreases because only the toner is consumed. Must be maintained at a constant rate, and therefore, there is a drawback that the developing device is increased in size. On the other hand, the one-component developer has the advantage that the apparatus can be downsized, and the development system is mainstream because it is easy to use in any environment (low temperature, low humidity, high temperature, high humidity). It is becoming.

  By the way, the one-component developer is classified into a magnetic one-component developer using a magnetic toner and a non-magnetic one-component developer using a non-magnetic toner. A magnetic one-component developing method using a magnetic one-component developer uses a developing sleeve provided with a magnetic field generating means such as a magnet inside to hold magnetic toner containing a magnetic material such as magnetite, and a layer thickness regulating member In many cases, it has been put into practical use in small printers. On the other hand, in the non-magnetic one-component developing method using a non-magnetic one-component agent, since the toner does not have a magnetic force, the toner replenishing roller or the like is pressed against the developing sleeve (developing roller) to put the toner on the developing sleeve. It is supplied, held electrostatically, developed with a layer thickness regulating member (regulating roller) and thinned, and has no advantage of being colored, since it does not contain a colored magnetic material. Since no magnet is used, the apparatus can be made lighter and lower in cost, and has recently been put into practical use in a small full-color printer or the like.

However, in the one-component development system, there are still many problems to be improved. In the two-component development system, a carrier is used as a means for charging and transporting toner, and the toner and the carrier are sufficiently stirred and mixed in the developing device and then transported to the developing sleeve for development. However, it is possible to maintain stable charging and conveyance, and it is easy to cope with a high-speed developing device. Compared to this, the one-component development method does not have a stable charging / conveying means such as a carrier, and therefore, charging and conveyance defects are likely to occur due to long-term use and high speed.
In particular, in the non-one-component development method, after the toner is conveyed onto the developing sleeve, the toner is thinned by the layer thickness regulating member and developed, and the toner and the friction charging member such as the developing sleeve or the layer thickness regulating member are used. Since the contact / friction charging time of the toner is very short, the amount of low-charged and reverse-charged toner tends to be larger than that in the two-component developing method using a carrier. In addition, means for transporting the toner by at least one toner transport member and developing the electrostatic latent image formed on the image carrier by the transported toner is employed. The toner layer thickness must be as thin as possible. For this reason, in order to receive a pressing force by the layer thickness regulating member, there is a problem that the external additive added to the toner surface is embedded in the toner and the chargeability and fluidity of the toner are greatly reduced. .

In a developing device that uses a non-magnetic one-component toner and replaces and uses a toner cartridge filled with a predetermined amount of toner, a problem arises due to a difference in charging ability between old and new toners when the toner is replenished. That is, in an image forming apparatus using a developing device having a toner replenishing port in a part in the longitudinal direction of the developing device, a partial density reduction may occur on the image after toner replenishment. FIG. 10 is a solid image immediately after replenishment of new toner in a conventional developing device, and is a diagram showing the defect. This phenomenon occurs due to the following.
11A and 11B are diagrams showing a normal toner distribution on the developing roller in a conventional developing device, in which FIG. 11A is a thin layer state by a regulating roller, and FIG. FIG. FIG. 12 shows the toner distribution on the developing roller when a new toner is replenished in a conventional developing device, where (a) is a thin layer state by the regulating roller, and (b) is the toner adhesion to the photoreceptor. It is a figure which shows a state. The normal toner thin layer has a configuration as shown in FIG. 11A in which regular charged toners are aligned. As shown in FIG. 11B, sufficient toner is developed on the photoreceptor as necessary. The However, when new toner is supplied into the developing unit filled with deteriorated toner at the end of the toner, new toner adheres to the surface of the developing roller and deteriorates as shown in FIG. The toner is reversely charged due to the difference in chargeability with the new toner, and constitutes a toner layer attached to the outside of the normally charged toner layer. As shown in FIG. 12B, when the toner layer is developed on the photosensitive member, the reversely charged toner on the surface layer acts as a barrier to reduce the development amount, thereby preventing normal image formation. As a result, a portion having a low density occurs on the image.
In order to solve this problem, for example, in Patent Document 1, a developing roller that carries a non-magnetic one-component developer, a supply roller that supplies developer in a replaceable toner cartridge to the developing roller, and a developing roller In addition to applying the developing bias voltage Vb, one or more bias applying means for applying the bias voltage sp to the supply roller, and at least control means for making the potential difference of the bias voltage variable are provided. A technique is disclosed in which the toner can be stably conveyed by increasing the potential difference | Vsp−Vb | when outputting a solid image after replacement of the toner cartridge by the control means.

JP 2000-112212 A

However, although the technique described in Patent Document 1 is effective for measures against density reduction that occurs uniformly in the longitudinal direction, there is a problem that an effect is not seen for a partial phenomenon.
Accordingly, the present invention has been made in view of the above-described problems, and a problem thereof is a developing device that uses a non-magnetic one-component developer, and image formation that occurs after the toner cartridge is replaced and the toner is replenished. It is an object of the present invention to provide a developing device that suppresses partial density unevenness and an image forming apparatus using the same.

The features of the present invention, which is a means for solving the above problems, are listed below.
1. A developing device of the present invention includes a developing unit for developing a latent image on the image bearing member with toner, and a toner cartridge for supplying toner to the developing unit are arranged in parallel, toner cartridge in the developing device detachable, the developing unit Has a first conveyance paddle for agitating the toner, and the toner cartridge has a second conveyance paddle for agitating the toner, and the communication port through which the toner is passed by communicating the developing unit and the toner cartridge. And a control valve that is provided corresponding to the communication port and that controls the amount of toner that passes through the communication port, and the control valve opens the communication port by contact with the first transport paddle Oscillates between a fixed position to be closed and an operating position to be closed, and when returning to the fixed position, a first space portion that opens to the communication port is formed on the downstream side in the moving direction. The second transport paddle forms a second space portion that opens to the communication port on the downstream side in the rotation direction when the tip end portion of the second conveyance paddle comes into contact with the inner wall surface of the toner cartridge by rotation and then comes off. When the toner flows from the toner cartridge into the first space, the toner is supplied to the developing unit, and when the toner flows from the developing unit into the second space, the toner is discharged to the toner cartridge. The developing unit includes a detecting unit that detects a remaining amount of toner in the developing unit, and the detecting unit includes a detecting unit that detects a remaining amount of toner so that the amount of toner in the developing unit becomes equal to or greater than a predetermined amount when the toner ends. it characterized by defining the vertical position.

2. An image forming apparatus of the present invention includes an image carrier that carries a latent image, a charging device that uniformly charges the surface of the image carrier, an exposure device that writes an electrostatic latent image on the surface of the charged image carrier, A developing device that visualizes the electrostatic latent image formed on the surface of the image carrier, a transfer device that transfers the visible image on the surface of the image carrier directly or via an intermediate transfer member, and an image carrier an image forming apparatus comprising: a chestnut over training apparatus the toner over on the body to clear over training, and a fixing device for fixing with heat and or pressure to the visible image on a recording member, before Kigen image device, the 1 characterized in that it is a developing device according to.
3. The image forming apparatus of the present invention is further configured such that the developing device can advance and retreat in a direction approaching the image carrier and vice versa, and applies acceleration to the developing device in a direction approaching the image carrier. An acceleration imparting mechanism is provided, and the acceleration imparting mechanism imparts an acceleration to the developing device in a direction approaching the image carrier at least immediately before performing a developing operation in the developing device.
4). The image forming apparatus of the present invention is further characterized in that the acceleration applying mechanism is not operated when the toner cartridge is replaced.
5. The image forming apparatus of the present invention also supports the developing device and the image carrier together, characterized in that it comprises a removable process mosquitoes over cartridge.
6). The process cartridge of the present invention, at least to support the developing device and the image carrier together, in the process mosquitoes over cartridge is detachably attached to the image forming apparatus main body, the developing device is the developing device according to the 1 characterized in that there.

  By the means for solving the above, in the developing device and the image forming apparatus of the present invention, it is possible to obtain stable image formation by suppressing partial density unevenness of image formation that occurs after the toner cartridge is replaced and the toner is replenished. Can do.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

FIG. 1 is a schematic view showing the configuration of the developing device of the present invention.
The developing device 30 includes a developing unit 31 that develops the latent image of the photoconductor 11 as an image carrier with toner as a developer, and a toner cartridge 32 that replenishes the developing unit 31 with toner.
The developing unit 31 faces the photoconductor 11 and supplies a toner onto the developing sleeve 31a, which is a developer carrying member that conveys the toner to a developing area formed between the developing unit 31 and the developing sleeve 31a. Supply roller 31b, a regulation roller 31c that is a layer thickness regulating member that regulates the amount of toner on the developing sleeve 31a, and a first conveyance paddle 31d that conveys toner.
The toner cartridge 32 includes first and second storage chambers 321 and 322 that store toner, second and third transport paddles 32a and 32b that transport the toner to the developing unit 31, and a second transport paddle 32a. A protruding rib 35 is provided at the bottom of the toner cartridge 32 where the toner cartridge rotates.
Here, a one-component developer is used as the developer. In contrast to replacing the developer as will be described later, it is very difficult to separate the toner from the carrier once mixed with the two-component developer. In the case of a one-component developer, the developer in the toner cartridge 32 and the developing unit 31 is basically the same and can be replaced, and can be applied to the developing device 30 of the present invention. In particular, it is preferable to use a non-magnetic one-component developer even for a one-component developer. In the non-magnetic one-component developer, the external additive on the toner surface has a great influence on the chargeability and fluidity of the toner. In a magnetic one-component developer, developability can be controlled by the strength of magnetization depending on the amount of magnetic material. In the non-magnetic one-component developer, the developability is greatly influenced by the charge amount and fluidity due to the external additive. Therefore, when used in the developing device 30 of the present invention, a stable toner surface state can be obtained.

In the developing device 30, the developing unit 31 and the toner cartridge 32 are arranged in parallel in the horizontal direction. Further, the toner cartridge 32 and the developing unit 31 are provided with a communication port through which the toner passes between the toner cartridge 32 and the developing unit 31. Further, a control valve is provided at the communication port on the developing unit 31 side.
The developing device 30 of the present invention allows the toner to pass through this communication port. Thereby, the toner consumed by the developing unit 31 is supplied from the toner cartridge 32 to the developing unit 31, also via the communication port, exits discharge the deteriorated toner in the developing unit 31 from the developing unit 31 to the toner cartridge 32 To do. The toner cartridge 32 can be replaced independently of the developing unit 31 independently.
The toner is subjected to a pressing force by the toner supply roller 31b and the regulating roller 31c in the developing unit 31. By receiving this pressing force, irregularities on the surface of the toner are chipped and the surface becomes smooth, and the adhesion to the photoconductor increases, making cleaning difficult. Therefore, when the environment becomes low humidity, cleaning failure may occur. In addition, although transferability is improved, fogging appears on a white background portion that has not been visually observed even if it has been transferred conventionally. Further, when the toner is pressed, the external additive present on the toner surface is buried inside the toner. This will be described in detail later with regard to the external additive, but the external additive is harder than the toner, and is therefore buried in the toner. As the external additive present on the toner surface decreases, the chargeability of the toner changes. In particular, since silica used as an external additive has a large specific surface area, the charge amount is high, and the charge amount of the toner varies greatly depending on the amount of the external additive on the toner surface due to burying. Another effect is that the fluidity of the toner is reduced by burying the external additive. This fluidity indicates the adhesion force of the toner. If the fluidity is high, the adhesion force between the toner and, for example, the photoreceptor is reduced. Similarly, the developability is improved by reducing the adhesion between the developing sleeve 31a and the toner. On the contrary, when the amount of the external additive existing on the toner surface is reduced due to the embedding, that is, the fluidity of the toner is lowered and the developability is lowered.

Therefore, in the developing device 30 of the present invention, the toner in the developing unit 31 is temporarily supplied to the toner cartridge 32 through the communication port 33 for supplying the toner consumed in the developing unit 31 from the toner cartridge 32 to the developing unit 31. The toner cartridge 32 is discharged and mixed with non-deteriorated toner in the toner cartridge 32 to reduce the existence ratio of the deteriorated toner amount, and then is supplied to the developing unit 31 through the communication port 33 and replenished. .
FIG. 2 is a schematic view showing the structure of the control valve 34 disposed in the developing unit 31 in the developing device of the present invention. The control valve 34 is provided corresponding to the communication port 33 of the developing unit 31, and the control valve 34 is attached to the support portion 34a and disposed in the housing. As shown in FIG. 2, the control valve 34 has a rectangular shape corresponding to each communication port 33, and the portions without the communication port 33 are alternately provided without the control valve 34. The support portion 34a is made of a metal having rigidity and uses SUS, Cu, or Al. The control valve 34 is an elastic resin film 34b and uses polypropylene, polyethylene, polyester resin, or fluororesin.
The first transport paddle 31d of the developing unit 31 includes a paddle film. This film may be a single film or a plurality of films. The first transport paddle 31d rotates and supplies the toner supplied from the toner cartridge 32 side to the developing sleeve 31a. The film may be plate-shaped. In addition, for the comb-like rectangular control valve 34 provided corresponding to the communication port 33, only the portion corresponding to the control valve 34 may be rectangular. Moreover, when providing two or more sheets, you may use combining these.

FIG. 3 is a diagram for schematically explaining a state in which toner is supplied to the developing unit 31 from the toner cartridge 32 side. The first transport paddle 31d rotates to hit the control valve 34, and the control valve 34 is pressed. Thereafter, the first transport paddle 31d passes, and the elastic control valve 34 is quickly bounced back, and at the same time, the toner pushed in from the toner cartridge 32 side passes through the communication port 33 and the developing unit 31. The toner is supplied by being attracted to the side.
FIG. 4 is a diagram for schematically explaining a state in which the toner on the toner cartridge 32 side is supplied. The toner cartridge 32 is transported to the first storage chamber 321 by the third transport paddle of the second storage chamber 322, and further transported to the developing unit 31 side by the second transport paddle. The second transport paddle includes a single paddle film, and transports the toner toward the developing unit 31 by rotating the film. Further, by providing the rib 35 in the first storage chamber 321, as shown in FIG. 5, when the previous paddle film hits the rib 35, the toner is blocked by the rib 35, and the rib 35 and paddle A space without toner is formed between the film for use. This space is gradually filled by the intrusion of toner with good fluidity, but a space is formed inside the toner for a certain period of time. Further, when the paddle film rotates, the toner also enters the space from above, so that there is no space inside the toner.
As the paddle film rotates in this state, the control valve 34 of the developing unit 31 is pressed against the paddle film of the first transport paddle 31d when the toner is pushed into the developing unit 31 side. The toner is moved and supplied from the toner cartridge 32 side to the developing unit 31 side through the communication port 33 by overlapping with the time when the control valve 34 is open (when it is in a fixed position).
Next, the toner in the developing unit 31 enters the opened control valve 34. After that, the paddle film of the first transport paddle 31d rotates and the toner that pushes the control valve 34 is pushed from the developing unit 31 side to the toner cartridge 32 side and the paddle for the second transport paddle in the first storage chamber 321. A space is formed inside the toner by the film, and the toner is moved and discharged from the developing unit 31 side to the toner cartridge 32 side through the communication port 33 by overlapping when the space reaches the communication port 33.

The movement of the first, second and third transport paddles and the movement of the toner between the developing unit 31 and the toner cartridge 32 in the developing device 30 at this time will be described in more detail.
FIG. 5 is a diagram schematically illustrating toner movement between the developing unit 31 and the toner cartridge 32. Here, the developing sleeve 31a and the like in the developing unit 31 are omitted.
In the developing device 30, as shown in FIG. 5A, the control valve 34 in the developing unit 31 has a predetermined angle θ with respect to the wall surface provided with the communication port. The first transport paddle 31d rotates a plurality of paddle films. The second and third transport paddles in the toner cartridge 32 rotate a single paddle film. As shown in FIG. 5 (2), in the developing unit 31, a plurality of paddle films push the control valve 34 in the first transport paddle 31 d, and at this time, the first transport paddle 31 d is between the control valve 34 and the communication port 33. Since the toner cartridge 32 side is also filled with toner, the toner cannot move through the communication port 33 and returns from the control valve 34 in the developing unit 31 into the developing unit 31 in the lateral direction. Next, as shown in FIG. 5 (3), in the first transport paddle 31 d, a plurality of paddle films push the control valve 34 further, and there is almost no gap between the control valve 34 and the communication port 33 ( (Operating position). Next, as shown in FIGS. 5 (4) and 5 (5), the first transport paddle 31d has a plurality of paddle films separated from the control valve 34, so that the control valve 34 is at its original angle (fixed position). At this time, a large gap is formed, and the toner is moved and supplied from the toner cartridge 32 side through the communication port 33 by forming a space.
Further, as shown in FIG. 5 (6), the paddle film of the first transport paddle 31d pushes the control valve 34 again by having a plurality of sheets. At this time, the paddle film of the second transport paddle is in contact with the rib 35 in the second storage chamber 322 in the toner cartridge 32. When further rotated, as shown in FIG. 5 (7), the paddle film of the first transport paddle 31 d further pushes the control valve 34, and a state without a gap is formed between the control valve 34 and the communication port 33. At this time, when the paddle film of the second transport paddle is rotated first from the rib 35, the rib 35 becomes an obstacle and the toner is not transported, so that a space is formed inside the toner. Further, as shown in FIGS. 5 (8) and 5 (9), the first transport paddle 31d is moved back to the original angle by the plurality of paddle films being separated from the control valve 34. In addition, by forming a space with a large gap, the toner lifted by the paddle film of the second transport paddle is further moved and supplied from the toner cartridge 32 side through the communication port 33.
However, next, as shown in FIG. 5 (10), the paddle film of the first transport paddle 31d pushes the control valve 34 again by having a plurality of sheets. Until now, there has been toner in the vicinity of the communication port 33 on the toner cartridge 32 side. However, when there is a space formed inside the toner, the developing unit 31 extends laterally from the control valve 34 in the developing unit 31. Instead of returning to the inside, it is moved from the developing unit 31 side to the toner cartridge 32 side through the communication port 33 and discharged. As shown in FIGS. 5 (11) and 5 (12), the paddle film of the first transport paddle 31 d pushes the control valve 34 again to further move from the developing unit 31 side to the toner cartridge 32 side. It is moved and discharged.
Further, by making the rotation speed of the first transport paddle 31d faster than that of the second transport paddle, as shown in FIGS. 5 (13) to 5 (16), the first transport paddle 31d moves from the developing unit 31 side to the toner cartridge 32 side. It can be discharged.
By repeating this, the toner can be moved through the communication port 33 between the developing unit 31 and the toner cartridge 32.

Here, by controlling the rotational speeds of the first transport paddle 31d in the developing unit 31 and the second transport paddle in the toner cartridge 32, the amount of supply / discharge due to the movement of the toner can be adjusted. In particular, by making the rotation speed of the first transport paddle 31d in the developing unit 31 faster than the second transport paddle in the toner cartridge 32, the number of times the space formed inside the toner contacts the communication port 33 can be reduced. By increasing the number of times the first transport paddle 31d pushes the control valve 34, the number of times of supplying the toner through the communication port 33 can be increased.
Further, the amount of supply / discharge due to the movement of the toner can be adjusted by the number of communication ports 33, and therefore one or more communication ports 33 can be provided. The number of the communication ports 33 is appropriately determined according to the image forming speed of the image forming apparatus main body.
Moreover, the control valve 34 provided corresponding to the communication port 33 is provided in the shape of a comb, and the adjacent control valves 34 can be operated alternately. This is because the paddle film of the first transport paddle 31d is provided in every other comb tooth shape corresponding to the comb tooth shaped control valve 34, and all the control valves 34 are composed of two paddle films. The control valves 34 can be operated alternately corresponding to the above. By alternately operating, the toner can be discharged evenly without forming a dead space of toner in the developing unit 31.

FIG. 6 is a view showing a first transport paddle according to the present invention. It is a perspective view of the 1st conveyance paddle used suitably for the present invention.
The first conveyance paddle 31d has films 311 and 312 attached to a shaft having a quadrangular cross section, and two of the films extend in opposite directions on opposite surfaces. The opposing film 311 has a concavo-convex shape (comb shape), and is a shape that shifts the two convex portions. In this way, adjacent control valves 34 can be driven alternately. The uneven portion corresponds to the position of the communication port 33, and the control valve 34 provided at the communication port 33 has a length that allows the convex portion of the film to be pushed in, and the concave portion does not contact the control valve 34.
Further, the base portion of the convex portion of the film is formed in a “C” shape so as to be wider than the leading end portion, and when the first transport paddle 31d rotates, the toner is also fed in the longitudinal direction by the convex portion of the film. A moving force is generated to cause longitudinal stirring in the developing unit 31.
Further, by the rotation of the first transport paddle 31d, the convex portion of the film pushes the control valve 34 and returns the toner under the control valve 34 to the toner cartridge 32 side.
Since the first transport paddle 31d is set to rotate faster than the second transport paddle 32a, the control valve 34 is operated several times by the first transport paddle 31d within the time when the cartridge has space. The toner can be returned to the toner cartridge 32 efficiently.
When the convex portion of the film passes through the control valve 34, the control valve 34 is released from the pressing force and returns to its original state by elasticity, and the toner on the control valve 34 is sent to the developing unit 31 side, and the toner is placed below the control valve 34. A space for drawing the toner in the cartridge 32 is formed.
By shifting the convex portions of the two films 311 of the first transport paddle 31d, the control valves 34 are alternately pushed and released, that is, the adjacent control valves 34 are driven alternately to develop the inside of the developing unit 31. The movement of the toner is improved, and the circulation property with the toner in the toner cartridge 32 can be improved.

Here, by adopting the paddle having the two comb-like films as described above, the circulation property of the toner and the stirring property in the longitudinal direction are improved. There is a tendency for the toner to increase, and the toner surface in the developing unit 31 undulates vertically, creating peaks and valleys. If the communication port 33 is clogged, the supply of toner from the toner cartridge 32 is hindered, so that the amount of toner supplied to the entire developing unit 31 is reduced. Further, since toner flows from the toner cartridge 32 in the vicinity of the bottom of the toner peak, a phenomenon that uniformity of toner agitation is not ensured is observed. In order to improve this point, as a result of the examination, the interdigital film 311 and the interdigital film 311 are at an angle of 90 degrees between the two interdigital films and are shorter than the convex parts of the interdigital film. By adding a non-existing film, that is, a rectangular film 312 to the first conveyance paddle 31d, the toner pile at the communication port 33 was broken, and the toner surface in the developing unit 31 could be made almost horizontal.
As described above, by arranging the rectangular film 312 between the two comb-shaped films 311 in the first transport paddle, the amount of toner supplied from the toner cartridge 312 and the toner to the toner cartridge 32 are set. It is possible to achieve a sufficient circulatory action with a stable return amount. In addition, since a local toner flow is not formed, uniform agitation can be maintained in the developing unit 31.

The width of the control valve 34 is 0 mm to 20 mm larger than the width of the communication port 33. If the control valve 34 is smaller than the communication port 33, the communication port 33 to which toner is supplied is blocked with toner on the developing unit 31 side, so that it is difficult to supply toner. Further, in discharging the toner, toner enters between the control valve 34 and the communication port 33, and a large amount of toner is discharged from the developing unit 31 side to the toner cartridge 32 side through the communication port 33 by discharging the inserted toner. However, since the width of the control valve 34 is reduced, a large amount of toner is discharged and the toner in the developing unit 31 is reduced.
On the other hand, toner is discharged from the side of the control valve 34 between the control valve 34 and the communication port 33 through the communication port 33 when the first transport paddle 31d is pushed. For this reason, when the width of the control valve 34 is larger than the communication port 33, the amount of toner that wraps around the communication port 33 is reduced, the amount of discharged toner is reduced, and toner replacement is reduced. The toner supplied from the communication port 33 moves downward from the communication port 33 and is mixed with the toner under the control valve 34. Therefore, when the width of the control valve 34 is increased, the number of supplied toners is reduced, and the homogeneity due to the mixing of the toner is lowered.
For these reasons, the width of the control valve 34 is at least the width of the communication port 33 and less than 20 mm. By setting this width, it is possible to easily control the supply / discharge of the toner, and to improve the homogeneity due to the mixing of the toner after the supply.

The interval between the control valves 34 is 2 mm to 20 mm. When the distance between the control valves 34 is less than 2 mm, the amount of toner entering between the control valve 34 and the communication port 33 is small, and the amount of toner that can be discharged is small. Further, if it exceeds 20 mm, the number of communication ports 33 that can be provided decreases, and the amount of toner supplied and discharged decreases.
The length of the control valve 34 is 10 mm to 25 mm. The size of the space formed between the control valve 34 and the communication port 33 is determined by the length of the control valve 34. Therefore, if the control valve 34 is less than 10 mm, the amount of discharged toner is reduced, and toner replacement is insufficient. If it exceeds 25 mm, the amount to be discharged increases and the amount of toner in the developing hopper decreases.
Further, the valve angle at the fixed position of the control valve 34 is set to 20 ° to 45 °, and the valve angle at the operating position is set to 0 ° to 15 °. Since the control valve is elastic and bends, the valve angle here is defined as an angle formed by a straight line connecting a portion where the control valve is in contact with the wall surface and the tip of the control valve and the wall surface. The size of the space formed between the control valve 34 and the communication port 33 is determined by the angle of the control valve 34. Therefore, if the angle of the control valve 34 is less than 20 °, the amount of toner discharged becomes small, and toner replacement becomes insufficient. When it exceeds 45 °, the amount discharged becomes large and the amount of toner in the developing hopper becomes small.

FIG. 7 is a schematic diagram showing the configuration of the image forming apparatus of the present invention.
The image forming apparatus 1 includes a photosensitive unit 10, a writing optical unit 20, a developing unit 30, an intermediate transfer unit 40, a secondary transfer unit 50, a fixing unit 60, a duplex printing paper reversing unit 70, and the like. Then, black (hereinafter referred to as Bk), cyan (hereinafter referred to as C), magenta (hereinafter referred to as M), and yellow (hereinafter referred to as Y) color images are successively developed on the photoreceptor belt 11 of the photoreceptor unit 10. These are then superimposed to form the final four-color full color image. Around the photoreceptor belt 11, a photoreceptor cleaning device 12, a charging roller 13, a plurality of developing devices 30, an intermediate transfer belt 41 of an intermediate transfer unit 40, and the like are disposed. The photosensitive belt 11 is stretched between a driving roller 14, a primary transfer counter roller 15, and a stretching roller 16, and is rotated by a driving motor. The writing optical unit 20 converts the color image data into an optical signal, performs optical writing corresponding to each color image, and forms an electrostatic latent image on the photosensitive belt 11. The writing optical unit 20 includes a semiconductor laser 21 as a light source, a polygon mirror 22, three reflecting mirrors 23, and the like.
The developing device 30 includes, in order from the lower side of the main body of the image forming apparatus 1, a Bk developing device 30K containing black toner, a C developing device 30C containing cyan toner, an M developing device 30M containing magenta toner, and a yellow. A Y developing device 30Y containing toner is provided. Here, a contact / separation mechanism for moving the developing devices in the left-right direction in the drawing to perform the contact / separation operation with respect to the photosensitive belt 11 is further provided.

  The toner in the developing device 30 is charged to a predetermined polarity, and a developing bias is applied to the developing sleeve 31 a by a developing bias power source, and the developing sleeve 31 a is biased to a predetermined potential with respect to the photosensitive belt 11. The contact / separation mechanism moves the developing device 30 toward the photosensitive belt 11 by the driving force when an electromagnetic clutch (not shown) for transmitting driving from the motor to each developing device 30 is turned on. At the time of development, any one selected from the developing device 30 moves and contacts the photosensitive belt 11. On the other hand, when the electromagnetic clutch is turned off and the drive transmission is released, the developing device that has been in contact with the photosensitive belt 11 moves away from the photosensitive belt 11.

In the standby state of the main body of the image forming apparatus 1, the developing devices 30K, C, M, and Y are also set at positions separated from the photosensitive belt 11, and when the image forming operation is started, the laser beam is based on the color image data. Is started, and electrostatic latent image formation is started (hereinafter, an electrostatic latent image based on Bk image data is referred to as a Bk electrostatic latent image; the same applies to C, M, and Y). Before the leading edge of the electrostatic latent image reaches the Bk developing position so that the leading edge of the Bk electrostatic latent image can be developed, the Bk developing sleeve 31a starts to rotate, and the Bk electrostatic latent image is transformed with Bk toner. develop. Thereafter, the developing operation of the Bk electrostatic latent image area is continued, but when the rear end portion of the Bk electrostatic latent image passes the Bk developing position, the K developing device 30K is separated from the photosensitive belt 11, The developing device of the corresponding color comes into contact with the photosensitive belt 11 in preparation for the development of the next color. This is completed at least before the leading edge of the electrostatic latent image based on the next image data reaches the developing position.
The intermediate transfer unit 40 includes an intermediate transfer belt 41, a belt cleaning device 42, a position detection sensor 43, and the like. The intermediate transfer belt 41 is stretched around a drive roller 44, a primary transfer roller 45, a secondary transfer counter roller 46, a cleaning counter roller 47, and a tension roller 48, and is driven and controlled by a drive motor (not shown). A plurality of position detection marks are provided in the non-image forming area at the end of the intermediate transfer belt 41, and any one of these position detection marks is detected by the position detection sensor 43, and this detection is performed. Image formation starts at the timing. Further, the belt cleaning device 42 includes a cleaning brush 42a, a contact / separation mechanism, and the like, while transferring the Bk image of the first color to the intermediate transfer belt 41 and the images of the second, third, and fourth colors. During the transfer to the intermediate transfer belt 41, the cleaning brush 42a is separated from the surface of the intermediate transfer belt 41 by the contact / separation mechanism.
Further, the secondary transfer unit 50 includes a contact / separation mechanism including a clutch or the like for contacting / separating the secondary transfer roller 51, the secondary transfer roller 51 to / from the intermediate transfer belt 41. The secondary transfer roller 51 swings about the rotation axis of the contact / separation mechanism in accordance with the timing when the transfer paper reaches the transfer position. The secondary transfer roller 51 and the secondary transfer counter roller 46 bring the transfer paper and the intermediate transfer belt 41 into contact with each other with a constant pressure. The secondary transfer roller 51 has a positional accuracy of parallelism with the secondary transfer counter roller 46 by a positioning member (not shown) provided in the intermediate transfer unit 40. Further, the contact pressure of the secondary transfer roller 51 with respect to the intermediate transfer belt 41 is made constant by a positioning roller (not shown) provided on the secondary transfer roller 51. At the same time as the secondary transfer roller 51 is brought into contact with the intermediate transfer belt 41, a transfer bias having a polarity opposite to that of the toner is applied to the secondary transfer roller 51, and the superimposed toner images on the intermediate transfer belt 41 are collectively transferred onto the transfer paper.

  On the other hand, at the time when the image forming operation is started, the transfer paper is fed from either the transfer paper cassette 80 or the manual feed tray 83 and is waiting at the nip of the pair of registration rollers 82. Then, when the leading edge of the four-color superimposed toner image on the intermediate transfer belt 41 approaches the secondary transfer roller 51, the registration roller pair 82 is driven so that the leading edge of the transfer paper coincides with the leading edge of the toner image. The transfer paper and the toner image are aligned. Then, the transfer paper is superimposed on the toner image on the intermediate transfer belt 41 and passes through the secondary transfer position. At this time, the transfer paper is charged by the transfer bias by the secondary transfer roller 51, and most of the toner image is transferred onto the transfer paper. Then, the transfer paper onto which the four-color superimposed toner images are collectively transferred from the intermediate transfer belt 41 is conveyed to the fixing unit 60, and the toner image is melted at the nip portion between the fixing belt 61 and the pressure roller 62 controlled to a predetermined temperature. It is fixed, sent out of the apparatus main body, and stacked face down on the paper discharge tray 84 to obtain a full color copy.

Furthermore, when performing duplex printing, the transfer paper that has passed through the fixing unit 60 is sent to the duplex printing paper reversing unit 70 by the duplex switching claw 85. In the double-sided printing paper reversing unit 70, the transfer paper is first guided in the direction of arrow D by the reversal switching claw 71, and after the rear end of the transfer paper passes through the reversal switching claw 71, the reversing roller pair 72 stops and the transfer paper also Stop. Then, the reverse roller pair 72 starts reverse rotation after a certain blank time, and the transfer paper starts to switch back. At this time, the reverse switching claw 71 is switched, and the transfer paper is sent to the registration roller pair 82. The transfer sheet sent to the registration roller pair 82 stands by at the nip of the registration roller pair 82 with the front and back reversed. Then, the registration roller pair 82 is driven at a predetermined timing, the transfer paper is sent to the secondary transfer position, and the four-color superimposed toner image is collectively transferred from the intermediate transfer belt 41, and then the toner image is melted by the fixing unit 60. It is fixed and sent out of the main body.
On the other hand, the surface of the photoconductor belt 11 after the primary transfer can be cleaned by the photoconductor cleaning device 12 and uniformly discharged with a charge removal lamp or the like to facilitate cleaning. Further, the surface of the intermediate transfer belt 41 after the toner image is transferred onto the transfer paper is cleaned by pressing the cleaning brush 42a of the belt cleaning device 42 with a contact / separation mechanism. The toner cleaned from the intermediate transfer belt 41 is stored in a waste toner tank 49.

Here, the developing device will be further described in detail. The developing device 30 includes a developing sleeve 31a that rotates while carrying toner on the surface to develop an electrostatic latent image on the surface of the photoreceptor belt 11, and a toner first conveyance paddle 31d that rotates to pump up and stir the toner. And a toner cartridge 32 for containing toner. The reason why it is divided into two units in this way is that the developing unit 31 has durability that can withstand even if the toner cartridge 32 is replaced several times.
8A and 8B are schematic views showing the configuration of the communication port 33 in the developing device of the present invention. FIG. 8A shows the configuration on the developing unit 31 side, and FIG. 8B shows the configuration on the toner cartridge side. A slide shutter is provided outside the housing of the developing unit 31, and an elastic member is attached to the slide shutter. The communication port 33 of the developing unit 31 is opened and closed by opening and closing this slide shutter. Further, the toner cartridge 32 side is an elastic member having a portion corresponding to the communication port 33 provided in the housing, and is opened so that toner can be prevented from spilling from the communication port 33 or the toner can be replenished. A sliding shutter is provided, and a fixing seal for fixing these to the housing is provided.
By arranging the toner cartridge 32 in the developing device, the slide shutter on the developing unit 31 side is opened, and the slide shutter on the toner cartridge 32 side is opened to form a communication port 33 through which toner can pass.
There are a plurality of communication ports 33 on the developing unit 31 side, and a slide shutter with an elastic member attached is provided between the developing unit 31 and the toner cartridge 32. By moving the slide shutter, the communication port 33 provided in the housing of the developing unit 31 is opened and closed. When there is no toner cartridge 32 or when it is not attached to the image forming apparatus main body, the communication port 33 is closed with a slide shutter to prevent toner from spilling from the developing unit 31.
Further, when the developing unit 31 is not provided or the toner cartridge 32 is not attached to the main body of the image forming apparatus, the communication port 33 is closed in order to prevent the toner from spilling out from the toner cartridge 32. Provide a slide shutter. An elastic member, a slide shutter, and a fixed seal are provided for the toner cartridge 32. The elastic member is preferably a foamed material such as urethane resin or silicone resin.
As shown in FIG. 8, a window portion opened to the slide shutter is provided corresponding to the communication port 33 provided in the developing unit 31 and the toner cartridge 32. When the communication port 33 is closed, the communication port 33 is closed where there is no window portion of the slide shutter, and when the communication port 33 is opened, the slide shutter is moved so that the window portion and the communication port 33 are aligned with each other. To communicate.

In the image forming apparatus 1, the developing device 30 transports the toner to the developer supply roller 31b while stirring the toner with the first transport paddle 31d in the developing unit 31, and the supply roller 31b rubs against the developing sleeve 31a. At the same time, the toner is rubbed and frictionally charged to charge the toner. The charged toner is attracted to the developing sleeve 31a with a mirror image force and conveyed. Thereafter, the amount of toner conveyed to the development area is regulated by the regulation roller 31c. A thin toner layer formed on the developing sleeve 31a is developed on the photosensitive belt with a developing bias in the developing region.
At this time, the toner rubbed against the developing sleeve 31a by the supply roller 31b receives a large pressing force, and the irregularities on the surface of the toner are scraped to become spherical and increase the adhesion force of the toner. Further, the external additive on the surface of the toner is buried by this pressing force and the fluidity is lowered, and further, the charge amount cannot be adjusted by the external additive, so that the charge amount is changed. Under these influences, the developing property of the toner is lowered, and further, the transfer property and the cleaning property are lowered.
Thus, the amount of deteriorated toner increases in the developing hopper, and the toner in the developing unit 31 decreases because the toner is consumed by development. Therefore, the toner is supplied from the toner cartridge 32 to the developing unit 31 through the communication port 33. In the toner cartridge 32, a second transport paddle 32 a and a third transport paddle 32 b slidably contacted with the inner wall of the toner cartridge main body 32 are provided in the first storage chamber 321 and the second storage chamber 322, respectively. Alternatively, the third transport paddles 32 a and 32 b rotate to push the toner toward the developing unit 31, and the toner is supplied to the developing unit 31 from the communication port 33.

Further, the toner in the developing unit 31 is discharged to the toner cartridge 32 through the communication port 33, and the toner is mixed with the toner in the toner cartridge 32. A large amount of unused toner is stored in the toner cartridge 32 and is mixed with the deteriorated toner in the developing unit 31. As a result of this mixing, the external additive present in large amounts on the surface of the unused toner is redistributed to the deteriorated toner, whereby the charge amount and fluidity of the deteriorated toner become close to those of the original unused toner. This is because the toner discharged from the developing unit 31 to the first storage chamber 321 is further transported to the second storage chamber 322 by the second transport paddle, and then to the first storage chamber 321 by the third transport paddle. Returned. During this time, the external additive is redistributed.
The toner approaching the original unused state is supplied again from the first storage chamber 321 of the toner cartridge 32 to the developing unit 31. A high-quality image can be obtained over a long period of time by forming a thin layer on the developing sleeve 31a and developing the toner with the toner that has approached the original state and the unused toner.

  However, the toner used in the developing device 30 tends to flow when the air is in between, but if the air is almost removed after the stationary state continues, it becomes difficult to move due to the cohesive force between the toner particles. As a result of being left standing, even if the toner is in a state where it is difficult to move, when a force that breaks the bonding between the toner particles is applied, voids are formed between the toner particles, and the fluidity is recovered. Therefore, in order to restore the fluidity of the toner in the stationary state as described above, an acceleration motion is given to the developing device 30. Hereinafter, the acceleration motion of the developing device 30 will be described in detail.

FIG. 9 is a schematic view showing the mechanism of the developing device.
Via a relay gear from the developing motor 37, the developing clutch 38, a driving shaft (not shown) that rotates when connected to the clutch 38 and the clutch 38 is turned on (the driving shaft is disposed directly under the developing roller), the driving shaft Are connected to a pair of left and right development drive gears (not shown) fixed to the front and rear, and a development roller drive gear that meshes with the development drive gear and is fixed to journals on both sides of the development roller 31a. When the developing motor 37 rotates and the developing clutch 38 is turned on at a predetermined timing, the driving shaft rotates, and the developing driving gear attached to the driving shaft rotates. The journal of the developing roller 31a can move in the same direction as the photosensitive belt and in the opposite direction. When the developing roller driving gear attached to the journal rotates in mesh with the developing driving gear of the driving shaft, The developing roller 31 a and the entire developing device 30 are pulled in the direction of the photosensitive belt 11.
After the developing device 30 has moved a certain distance, the developing device 30 stops at the same position while the developing roller 31a rotates by striking the stopper so that the developing device 30 does not bite into the photoreceptor. To do. This series of movements is an acceleration movement given to the developing device 30. This acceleration movement adjusts the timing and rotation starting torque, the spring force for initially setting the developing device 30 backward, the material of the stopper, etc. in the same direction as the toner supply and discharge directions of the developing device 30. Accelerate when retracting, and decelerate when hitting the stopper.

Due to the action of the acceleration and the vibration acting by giving the acceleration, the cohesive force between the toner particles that are difficult to move in the developing unit 31 and the toner cartridge 32 is released, and a gap is formed between the particles, so that the entire toner is Easy to move. In this way, even when the image forming apparatus has not been used for a long period of time or when the toner's external additives (silica, etc.) have decreased and fluidity has deteriorated over time, the control valve, etc. According to the movement, a toner flow can be formed, and problems with image quality due to insufficient stirring ability of the toner and deterioration of charging property can be suppressed.
In addition, it is also effective to periodically apply the acceleration motion to the developing device 30 when the developing device 30 is not used.
Further, if the acceleration motion of the developing device 30 is performed at least before (immediately before) the developing operation, the subsequent rotation of each transport paddle in the developing device 30 and the operation of the control valve 34 cause the toner to move. It is possible to make the flow of the flow effectively, which is more preferable.

Here, when the toner end is detected and the amount of toner in the developing hopper is small, new toner replenished from the newly replaced toner cartridge easily reaches the vicinity of the developing roller. However, as described above, when new toner is supplied to the developing hopper occupied by the deteriorated old toner at the end of the toner, new toner adheres to the surface of the developing roller, and the deteriorated old toner is new. Due to the difference in chargeability with the toner, a reverse charge is applied to form a toner layer attached to the outside of the normally charged toner layer. In this toner layer structure, when developing on the photoreceptor, the reversely charged toner on the surface layer becomes a barrier, and the development amount is reduced, and normal image formation cannot be performed. As a result, a portion having a low density is partially generated on the image. Therefore, in the embodiment of the present invention, the amount of toner in the developing hopper at the end of the toner is set to at least 150 g, preferably at least 170 g, so that the new toner is sufficiently different from other old toner until it reaches the vicinity of the developing roller. The new toner is supplied onto the developing roller while maintaining a low mixing ratio of the new toner. Specifically, in the present invention, the toner amount in the developing hopper when the toner end is detected is adjusted by adjusting the vertical position of a transmission type LED sensor (not shown) which is a toner end sensor in the developing hopper. ing. As a result, it is possible to prevent the phenomenon of partial density reduction on the image, and stable image formation is possible.
In addition, immediately after the toner cartridge is replaced at the end of the toner, the developing device having a mechanism for controlling the supply / discharge of the toner between the developing unit and the toner cartridge as described above can be driven back and forth including acceleration motion. In this case, the toner replenished from the toner cartridge vigorously flows into the developing hopper, reaches the vicinity of the developing roller, and the old and new toners are abruptly mixed, so that it is inevitably easy to create a cause of density reduction. Therefore, in the present invention, the development device is not driven back and forth immediately after replacement of the toner cartridge, and a new toner is naturally replenished while the toner amount in the development hopper is reduced. The toner charge is stabilized, and the phenomenon of partial density reduction on the image can be prevented, thereby enabling stable image formation.

1 is a schematic diagram illustrating a configuration of a developing device of the present invention. It is the schematic which shows the structure of the control valve arrange | positioned at the image development unit in the image development apparatus of this invention. FIG. 6 is a diagram for schematically explaining a state in which toner is supplied from a toner cartridge side to a developing unit. FIG. 6 is a diagram for schematically illustrating a state in which toner on a toner cartridge side is supplied. FIG. 5 is a diagram schematically illustrating toner movement between a developing unit and a toner cartridge. FIG. 5 is a diagram schematically illustrating toner movement between a developing unit and a toner cartridge. FIG. 5 is a diagram schematically illustrating toner movement between a developing unit and a toner cartridge. It is a figure which shows the 1st conveyance paddle which concerns on this invention. 1 is a schematic diagram illustrating a configuration of an image forming apparatus of the present invention. 2A and 2B are schematic diagrams illustrating a configuration of a communication port in the developing device of the present invention, in which FIG. 3A illustrates a configuration on a developing unit side, and FIG. 3B illustrates a configuration on a toner cartridge side. It is the schematic which shows the mechanism of a developing device. It is a solid image immediately after replenishment of new toner in a conventional developing device, and is a diagram showing the problem. FIG. 7 is a diagram illustrating a normal toner distribution on a developing roller in a conventional developing device, where (a) is a thin layer state by a regulating roller, and (b) is a diagram illustrating a state of toner adhesion to a photoreceptor. is there. The toner distribution on the developing roller when new toner is replenished in a conventional developing device is shown, (a) is a state of a thin layer by a regulating roller, and (b) is a diagram showing the state of toner adhesion to the photoreceptor. It is.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 11 Photoconductor 12 Photoconductor cleaning unit 13 1st charging means 14 Drive roller (photoconductor)
15, 16 Followed roller (photosensitive member)
20 exposure means 21 registration roller 25 paper feed roller 26 contact / separation mechanism 30 developing device 31 developing unit 31a developing sleeve (developing roller)
31b Supply roller 31c Restriction roller 31d First transport paddle 31e Slide shutter 31f Elastic member 31g Window 31h Development hopper 311 Comb-shaped film 312 Rectangular film 32 Toner cartridge 321 First storage chamber 322 Second storage chamber 32a Second transport paddle 32b Third transport paddle 32c Slide shutter 32d Elastic member 32e Fixed seal 33 Communication port 34 Control valve 34a Support part 34b Film 35 Rib 36 Cam 37 Development motor 38 Development clutch 40 Intermediate transfer belt unit 41 Intermediate transfer belt 42 Belt cleaning unit 43 Mark Sensor 44 Drive roller (intermediate transfer belt)
45 Primary transfer bias rollers 46, 47 Followed roller 49 Belt position detection mark 50 Secondary transfer unit 51 Secondary transfer bias roller 60 Fixing means 70 Double-sided transport device 80 Paper feed device 81 Paper feed roller 83 Manual feed tray 90 Transfer material

Claims (6)

A developing unit for developing the latent image on the image carrier with toner;
In a developing device in which a toner cartridge for supplying toner to a developing unit is arranged in parallel, and the toner cartridge is detachable ,
The developing unit has a first transport paddle for stirring the toner,
The toner cartridge has a second transport paddle for stirring the toner,
A communication port that allows toner to pass by communicating the developing unit and the toner cartridge; and a control valve that is provided corresponding to the communication port and controls the amount of toner that passes through the communication port.
The control valve swings between a fixed position where the communication port is opened by contact with the first transport paddle and an operating position where the communication port is closed, and returns to the fixed position. Forming a first space that opens to the communication port on the downstream side in the movement direction;
The second transport paddle forms a second space portion that opens to the communication port on the downstream side in the rotation direction when the front end portion of the second transport paddle is released after contacting the inner wall surface of the toner cartridge by rotation.
Toner flows from the toner cartridge into the first space to supply toner to the developing unit;
A developing device that discharges toner to the toner cartridge when toner flows from the developing unit into the second space,
The developing unit has a detecting means for detecting the remaining amount of toner,
A developing device characterized in that the upper and lower positions of the detecting means are determined so that the amount of toner in the developing unit becomes equal to or larger than a certain amount at the time of toner end . An image carrier that carries a latent image, a charging device that uniformly charges the surface of the image carrier, an exposure device that writes an electrostatic latent image on the surface of the charged image carrier, and a surface formed on the surface of the image carrier. A developing device that visualizes the electrostatic latent image, a transfer device that transfers the visible image on the surface of the image carrier directly or via an intermediate transfer member, and a cleaning that cleans the toner on the image carrier In an image forming apparatus comprising an apparatus and a fixing device that fixes a visible image on a recording member with heat and / or pressure,
The developing device according to claim 1, wherein the developing device is a developing device according to claim 1.
An image forming apparatus. The image forming apparatus according to claim 2.
The developing device is configured to be able to advance and retreat in a direction approaching the image carrier and in the opposite direction.
An acceleration applying mechanism that applies acceleration to the developing device in a direction approaching the image carrier;
The image forming apparatus , wherein the acceleration applying mechanism applies an acceleration to the developing device in a direction approaching the image carrier at least immediately before performing a developing operation in the developing device. The image forming apparatus according to claim 3 .
An image forming apparatus , wherein the acceleration applying mechanism is not operated when the toner cartridge is replaced . The image forming apparatus according to claim 2,
An image carrier and a developing device are integrally supported, and a removable process cartridge is provided.
An image forming apparatus. At least the process cartridge that integrally supports the image carrier and the developing device and is detachable from the image forming apparatus main body,
The developing device according to claim 1, wherein the developing device is a developing device according to claim 1.
A process cartridge characterized by that.

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