JP2008275745A - Developing device, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately detect a toner amount in a developing device in any case, and then to suitably mix a supplied developer and a developer in the developing device to obtain an image of high quality. <P>SOLUTION: In an image forming apparatus, a partition is arranged between a toner surface detecting means 415 and a toner replenishment opening 418 so that a lower end 417a of the partition is below higher one of an agent surface range lower end α of toner and the lowest point δ of a vertical optical path width upper-end line 415e of an optical path of the toner surface detecting means 415 in an agitation chamber 416b and further above the lowest point λ of a vertical optical path width lower-end line 415d of the optical path of the toner surface detecting means 415 in the agitation chamber 416b. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus having a function of forming an image on a recording material (recording medium), and more particularly to a developing device and a process cartridge provided in these apparatuses.

  Conventional electrophotographic image forming apparatuses are known as follows. When the toner as the developer is used and the toner of the image forming apparatus is consumed, the toner is replenished to the apparatus by replacing the toner replenishing container that can be attached to and detached from the image forming apparatus with a new toner replenishing container. It is.

  FIG. 10 is a longitudinal sectional view showing an example of a schematic configuration of a conventional image forming apparatus.

  As shown in FIG. 10, for example, a drum-shaped electrophotographic photosensitive member (hereinafter simply referred to as “photosensitive drum”) as an image carrier, that is, a photosensitive drum 100, is provided at the substantially central portion of the conventional image forming apparatus. It is supported rotatably in the direction of the arrow.

  When the image forming operation is started, the charging unit 200 uniformly charges the surface of the photosensitive drum 100. Thereafter, for example, a laser irradiation unit 300 as an exposure unit exposes a surface charged by a laser corresponding to image information, and forms an electrostatic latent image on the surface. The developing device 400 visualizes the formed electrostatic latent image with toner to form a so-called toner image.

  This toner image is electrostatically transferred onto the recording material P by a transfer electric field formed between the photosensitive drum 100 and the transfer roller 600 by, for example, a transfer roller 600 as transfer means. Thereafter, the unfixed toner image on the recording material P is fixed on the recording material P by heat and pressure in the fixing device 800 (heating roller 800a, pressure roller 800b).

  In addition, transfer residual toner or the like remaining on the surface of the photosensitive drum 100 after the transfer of the toner image is removed by, for example, a cleaning device 700 including a blade-shaped cleaning member, and the photosensitive drum 100 can continue to form an image. Become.

  Next, the developing device 400 used in the conventional image forming apparatus will be further described.

  The developing device 400 includes a developer carrier 401 made of an elastic material that conveys toner to the photosensitive drum 100. Then, the developer carrying member 401 is brought into contact with the surface of the photosensitive drum 100 to develop the electrostatic latent image. Such a configuration is known as a so-called contact development method.

  There is also known a system in which toner is replenished sequentially or collectively to the developing device in accordance with a decrease in toner in the developing chamber. The developing device 400 uses a one-component developer as a developer, and particularly uses a non-magnetic one-component developer. Hereinafter, unless otherwise specified, the one-component developer is simply referred to as “toner”.

  In the developing device 400, the developing container 406 contains toner. Further, the developing container 406 is partially open on the side facing the photosensitive drum 100, and the developing roller 401 as the developer carrying member rotates in the direction of the arrow R5 so as to be partially exposed from the opening. Supported as possible.

  An agitation paddle 404, which is a means for agitating and conveying the developer, is provided at the inner side opposite to the opening of the developing container 406 so as to be rotatable in the direction of arrow R6. The agitation paddle 404 agitates the toner and conveys the toner to a region D in the vicinity of a contact portion between the developing roller 401 and a supply roller 403 described later.

  A supply roller 403 as a developer supply unit is formed of an elastic body and is provided to rotate in contact with the development roller 401. The toner conveyed by the stirring paddle 404 is made uniform by once becoming dense in the region D as the supply roller 403 rotates in the direction of arrow R7. Thereafter, with the friction between the developing roller 401 and the supply roller 403 that are in contact with each other by counter rotation, electric charge is applied to the toner by friction. Here, counter rotation refers to rotation in which opposing surfaces (rubbing surfaces) advance in opposite directions.

  The toner to which electric charge is applied in the rubbing region between the developing roller 401 and the supply roller 403 is supplied onto the developing roller 401 by receiving a mirroring force by the charged electric charge. Further, the developing container 406 is provided with a blade 402 as a developer layer thickness regulating member that is pressed against the developing roller 401. The toner on the developing roller 401 passes through the contact area with the blade 402 as the developing roller 401 rotates, so that the layer thickness is regulated and applied to the developing roller 401 in a thin layer. At this time, the toner is given a sufficient charge for development by friction between the developing roller 401 and the blade 402.

  Thereafter, as the developing roller 401 rotates, the toner is conveyed to a developing region (developing nip) N where the photosensitive drum 100 and the developing roller 401 abut. On the other hand, a voltage is applied to the developing roller 401 from a power source (not shown) between the photosensitive drum 100 and the developing roller 401 to form a developing electric field. Therefore, the toner on the developing roller 401 is transferred to the electrostatic latent image on the photosensitive drum 100 by the action of the developing electric field, and a toner image is formed.

  At this time, as shown in FIG. 10, for example, in the case of a developing device that employs a method in which the developing roller 401 contacts and rotates on the surface of the photosensitive drum 100, the following toner is rubbed against the photosensitive drum 100. become. That is, not only toner that selectively adheres to the latent image and forms a toner image, that is, toner that contributes to development but also toner carried on the developing roller 401 is rubbed with the photosensitive drum 100. . Such a state is hereinafter referred to as a state in which toner (developer) is “contacted” on the photosensitive drum 100.

  Of the toner applied to the developing roller 401 and carried and conveyed to the developing nip N, the toner remaining on the developing roller 401 without contributing to the development is supplied by the supply roller (developer supply and stripping means) 403. It is peeled off from the developing roller 401 by rubbing. A part of the removed toner is supplied again onto the developing roller 401 by the supplying roller 403 together with the toner newly supplied to the supplying roller 403, and the rest is returned to the developing container 406.

  Further, a removable toner hopper 500 is provided above the developing container 406 so that toner can be replenished as necessary.

  However, an image forming apparatus having a configuration in which development is performed in a state where toner is in contact with an image carrier, such as the conventional image forming apparatus described above, has the following problems.

That is, the toner is subjected to the following rubbing in the order in which it is conveyed from the developing container 406 and is subjected to development. That is, rubbing between the supply roller 403 and the developing roller 401, rubbing when the toner layer thickness is regulated between the developing roller 401 and the blade 402, and between the photosensitive drum 100 and the developing roller 401. Each is subjected to rubbing when it is developed in, and used for development. Further, the toner that has not contributed to the development is peeled off from the developing roller 401 and collected in the developing container 406, so that it is rubbed again by the supply roller 403.

  As described above, each of the series of operations accompanying the image forming operation involves the contact between the toner and the member, and the toner repeatedly receives a load at each contact. Due to such a load, a part or all of the toner in the developing container 406 is damaged, and an additive such as silica added to the toner surface is embedded in the toner particle itself or released. To do. Therefore, the toner gradually deteriorates in performance such as fluidity and chargeability required as a developer.

  According to the study by the present inventors, such deteriorated toner may cause aggregation due to mutual toner when replenishing non-deteriorated toner due to decrease in chargeability, fluidity, and the like. I found out that Then, when replenishing toner that has not deteriorated causes aggregation due to mutual toner, density unevenness, fogging, and toner blurring occur on the image (toner lump drops on the image). There was a case.

  In particular, this phenomenon may appear by lowering the melting point of the toner as a toner characteristic, particularly from the viewpoint of the fixing characteristic, due to the recent demand for higher printing speed and energy saving of the image forming apparatus. Further, it may also appear when an external additive such as silica gives a large fluidity or chargeability to the toner itself.

  In order to prevent this problem, it is necessary to sufficiently mix and agitate the toner in the developing container and the replenished toner and to reduce the amount of toner replenished at a time as much as possible. For the former, the toner surface with respect to the agitating member is controlled within an appropriate range and toner is replenished there, and for the latter, changes in the toner amount are accurately detected and replenishment control is performed accordingly. It is very effective (see Patent Document 1).

  Examples of the method for detecting the amount of one-component toner in the developing container include the following. It includes a method using a piezo element, an electrostatic antenna method for measuring a change in capacitance between electrodes, a method for detecting torque of a stirring member, etc., and an optical path passing through the developing container, and depending on the state of transmitted light. This is a light detection method for determining the toner amount.

As one of the light detection methods, a light transmission window is provided in the developing container, and the toner is flowed while cleaning the toner on the inner surface of the window in conjunction with a stirring member in the developing container. In some cases, the amount of toner is detected by counting the light transmission time that varies depending on the amount of light. This is very effective in accurately detecting a change in the toner amount.
JP 2005-148446 A

  By the way, in the developing device, in order to sufficiently stir the replenished toner and to accurately detect the toner amount with respect to the agitating member, the toner replenishing port and the toner amount detecting means are disposed relatively close to each other. It becomes.

  Further, the inventors have found that it is desirable to replenish the replenished toner in a finely dispersed state in order for the replenished toner to be rapidly and sufficiently stirred.

In such an improved configuration, when a high-density image is continuously output and the toner replenishment amount temporarily increases, the fine replenishment toner may be diffused and scattered in the form of a mist. As described above, when the amount of toner is detected using the light detection method, there is a new concern that the light path for light detection is blocked by the mist-like supply toner.

  In such a case, in spite of the large amount of toner consumption, conversely, as the toner amount detection, it is erroneously determined that the amount of toner is large, and toner replenishment is reduced.

  An excessive reduction in the toner amount in the developing container causes insufficient stirring and mixing of toner, resulting in image defects such as density unevenness, fogging, and toner blurring.

  The present invention has been made in view of the circumstances as described above. In any case, the amount of toner in the developing device is accurately detected, and as a result, the replenished developer and the developer in the developing device are mixed. The aim is to do it properly and to obtain high quality images.

In order to achieve the above object, the present invention provides:
A developer supply port through which developer is supplied by the developer supply means;
Developer agitation means movable to mix the developer replenished from the developer replenishing port and the developer present in the developing device;
Optical agent level detecting means for irradiating light near the developer agitating means and detecting the developer surface height of the developer in the vicinity of the developer agitating means by light transmission state;
With
In the developing device for developing the electrostatic latent image formed on the image carrier with the developer replenished by the developer replenishing unit based on the detection result of the agent surface detecting unit,
A partition wall provided between the developer replenishing port and the agent surface detecting unit, and preventing a developer replenished from the developer replenishing port from affecting the light transmission state of the agent surface detecting unit. It is characterized by providing.

A developer supply port for supplying the developer by the developer supply means;
Developer agitation means movable to mix the developer replenished from the developer replenishing port and the developer present in the developing device;
Optical agent level detecting means for irradiating light near the developer agitating means and detecting the developer surface height of the developer in the vicinity of the developer agitating means by light transmission state;
With
In the developing device for developing the electrostatic latent image formed on the image carrier with the developer replenished by the developer replenishing unit based on the detection result of the agent surface detecting unit,
A stirring chamber including the developer replenishing port, the developer stirring means, and the agent level detection means;
A developing chamber including a developer carrier for carrying and conveying the developer;
A developer conveying means provided in the developing chamber for conveying the developer in the developing chamber to the stirring chamber;
Provided between the developer replenishing port and the agent surface detecting means in the stirring chamber, the developer replenished from the developer replenishing port affects the light transmission state of the agent surface detecting unit. Prevent the partition wall,
With
An area in which the developer in the developing chamber conveyed by the developer conveying means is detected by the agent level detecting means in the stirring chamber, an area in the vicinity of the partition in the stirring chamber, and the developer replenishment in the stirring chamber The structure is such that the region in the vicinity of the mouth circulates in the order of the developing chamber.

According to the present invention, in any case, the amount of toner in the developing device is accurately detected, and as a result, the developer to be replenished and the developer in the developing device are appropriately mixed to obtain a high-quality image. Is possible.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments. Further, the materials, shapes, etc. of the members once described in the following description are the same as those in the first description unless otherwise described.

  In the present invention, for example, an electrostatic latent image formed on an image carrier using an electrophotographic system or an electrostatic recording system is visualized by a developing action of a developing device to form a visible image, and then the visible image is recorded. The present invention relates to an image forming apparatus that obtains a permanent image by transferring and fixing on a material. In particular, the present invention relates to a developing device and a process cartridge used in such an image forming apparatus.

  Here, the electrophotographic image forming apparatus includes, for example, a copying machine, a printer (for example, an LED printer, a laser beam printer, etc.), a facsimile apparatus, and a word processor.

  The process cartridge is a cartridge in which a charging unit, a developer carrying member or a cleaning unit, and an electrophotographic photosensitive member are integrally formed, and the cartridge can be attached to and detached from the image forming apparatus main body. Alternatively, at least one of the charging unit, the developer carrying member, and the cleaning unit and the electrophotographic photosensitive member are integrally formed into a cartridge that can be attached to and detached from the image forming apparatus main body. Alternatively, it means that at least the developer carrying member and the electrophotographic photosensitive member are integrated into a cartridge so as to be detachable from the image forming apparatus main body.

  FIG. 1 is a schematic cross-sectional view illustrating a schematic configuration of an image forming apparatus according to Embodiment 1 of the present invention. In this embodiment, an image forming apparatus that forms a black monochrome image will be described. However, the present invention is not limited to these embodiments, and is also applicable to a color image forming apparatus that forms a plurality of colors. I can do it.

  The image forming apparatus X according to the present embodiment includes an image carrier on which an electrostatic latent image is formed, a developing device that develops the electrostatic latent image, a developer replenishing unit that replenishes the developer to the developing device, and development Control means for controlling the replenishment of developer from the agent replenishing means. Here, in this embodiment, the photosensitive drum 110 is illustrated as the image carrier, and the toner hopper 510 is illustrated as the developer supply means.

  In the image forming apparatus X, a drum-shaped electrophotographic photosensitive member, that is, a photosensitive drum 110 is supported substantially at the center so as to be rotatable in the direction of the arrow R1. When the image forming operation is started, a charging roller 210 as a charging unit uniformly charges the surface of the photosensitive drum 110. Thereafter, a laser irradiation unit 310 as an exposure unit exposes the surface of the photosensitive drum 110 with a laser beam corresponding to image information to form an electrostatic latent image on the photosensitive drum 110.

  In this embodiment, the charged charge on the photosensitive drum 110 is negative. Then, the electrostatic latent image corresponding to the image information is formed in a portion where the negative charged charge is attenuated by the exposure with the laser beam from the laser irradiation unit 310.

  Thereafter, as the photosensitive drum 110 rotates, the electrostatic latent image is visualized by toner that is a kind of developer supplied by the developing device 410 by the developing action of the developing device 410, and the toner image is formed on the photosensitive drum 110. It is formed.

  In this embodiment, the developing method is a reversal developing method. Therefore, the toner having the same polarity (negative polarity) as the charged charge adheres to the portion (image portion) where the negative charged charge on the photosensitive drum 110 is attenuated. Further, the toner is supplied to the developing device 410 from a toner hopper 510 as a developer containing means.

  On the other hand, the recording material P stored in a cassette (not shown) is transferred from the toner image on the photosensitive drum 110 to the transfer region where the photosensitive drum 110 and the transfer roller 610 as a transfer unit are in contact by the feeding roller 910. It is conveyed synchronously.

  When the toner image on the photosensitive drum 110 and the recording material P reach the transfer area, the toner image is transferred onto the recording material P by a transfer electric field formed in the transfer area by the transfer roller 610. Thereafter, the unfixed toner image carried on the recording material P is heated by a fixing unit (heat roller) 810a included in the fixing device 810 and pressed by the pressing unit 810b, and is thus permanently imaged on the recording material P. As established.

  In addition, the photosensitive drum 110 that has finished transferring the toner image is prepared for the subsequent image forming operation by removing residual toner remaining on the surface of the photosensitive drum 110 by a cleaning device 710 having a blade-like cleaning unit.

  Next, the developing device 410 and the toner hopper 510 will be further described.

  FIG. 2 is a cross-sectional view of a main part illustrating a schematic configuration of the developing device 410 and the toner hopper 510 according to the present embodiment.

  In the present embodiment, the developing device 410 includes a developer carrier, a developer supply unit, a developer regulating unit, a developer stirring unit, and a agent level detecting unit. Here, the developing roller 411 as a developer carrying member carries and conveys toner, and contacts the toner with the photosensitive drum 110 to develop the electrostatic latent image. A supply roller 413 as developer supply means supplies toner to the development roller 411. A blade 412 as a developer regulating unit regulates the toner supplied by the supply roller 413 and forms a thin layer of toner on the developing roller 411. The developer agitating means has an agitating member 414 and a rotating shaft 414a that rotatably supports the agitating member 414. The toner replenished from the developer replenishing means and the toner present in the developing device. Movable to mix with. The toner surface detection unit 415 as the agent surface detection unit is an optical detection unit that irradiates light toward the vicinity of the stirring member 414 and detects the toner surface height of the toner in the vicinity of the stirring member 414 according to the light transmission state. is there.

  Further, the developing device 410 employs a contact development method in which development is performed in a state where the developing roller 411 is brought into contact with the photosensitive drum 110 and toner is “contacted” with the photosensitive drum 110.

  The toner used in this embodiment is a negatively charged nonmagnetic one-component developer (toner). More specifically, the toner is intended to save energy in the fixing device by forming an internal structure containing a low softening point substance. As a toner production method, for example, a developer production method by a suspension polymerization method described in JP-B-63-10231, JP-A-59-53856, JP-A-59-61842, or the like is used. I can do it. Part or all of the toner is formed by such a polymerization method.

  The toner is a spherical toner having a volume average particle diameter of 6 μm. This toner has a so-called core / shell internal structure in which a low softening point substance is coated with an outer shell resin, and the shell portion in this structure is formed by a polymerization method.

  According to the suspension polymerization system at room temperature or under pressure, spherical fine particles having a particle size of 3 to 8 μm can be obtained relatively easily with a sharp particle size distribution. For this reason, the distribution of the weight specific charge becomes sharp, and uniform development according to the development contrast is performed.

  In addition to the suspension polymerization method, it is possible to use a toner manufactured using the following method. It is a dispersion polymerization method in which a toner is directly produced using an aqueous organic solvent in which the monomer is soluble and the polymer obtained by polymerization is insoluble, or directly in the presence of a water-soluble polar polymerization initiator. For example, an emulsion polymerization method represented by a soap-free polymerization method that forms a toner by polymerization.

  The toner used as a developer in this embodiment has a substantially spherical shape with a shape factor SF-1 in the range of 100 to 140 and a shape factor SF-2 in the range of 100 to 120.

Here, the shape factors SF-1 and SF-2 are defined as follows. First, 100 toner images are randomly sampled using FE-SEM (S-800) manufactured by Hitachi. Then, the image information is input into the image analysis apparatus (Luxex 3) manufactured by Nicole via the interface and analyzed, and is defined as a value obtained by calculating from the following equations (1) and (2). That is,
SF-1 = (MXLNG) ² / AREA × (π / 4) × 100 Formula (1)
SF-2 = (PERI) ² / AREA × (1 / 4π) × 100 Formula (2)

  Here, AREA means the toner projection area, MXLNG means the absolute maximum length of the projection image, and PERI means the circumference of the projection image. The shape factor SF-1 indicates the degree of sphere, and when it is larger than 140, it gradually leaves the sphere and becomes indefinite. On the other hand, the shape factor SF-2 indicates the degree of unevenness, and if it is larger than 120, the surface unevenness becomes remarkable.

  Further, in this embodiment, an additive such as silica is externally added to the above toner in order to improve characteristics such as chargeability and fluidity. Alternatively, other types of additives can be appropriately selected as long as they have similar functions. For example, metal oxides such as aluminum oxide, tin oxide, strontium titanate, zinc oxide and magnesium oxide, nitrides such as silicon nitride, carbides such as silicon carbide, and carbon allotropes such as carbon black and graphite can be selected. Also, metal salts such as calcium sulfate, barium sulfate, calcium carbonate, and fatty acid metal salts can be selected.

  As described above, a toner having an internal structure including a core / shell structure may be destroyed by a load accompanying an image forming operation. In that case, the toner loses its rigidity and is easily fused to the developing roller 411 and the blade 412.

  Next, each member arranged in the developing device 410 will be described.

  The developing device 410 has toner in the developing container 416. In the developing container 416, toner moves from the developing chamber 416a in which the developing roller 411, the supply roller 413, and the blade 412 are disposed, the stirring chamber 416b in which the stirring member 414 is disposed, and the stirring chamber 416b to the developing chamber 416a. Has an opening 416c. Here, the stirring chamber 416b is disposed above the developing chamber 416a with the opening 416c interposed therebetween.

Further, the developing container 416 is provided with an opening 416 d in a part on the side facing the photosensitive drum 110. The developing roller 411 is supported by the developing container 416 so as to be partially exposed from the opening 416d and to be rotatable in the arrow R2 direction. The developing roller 411 includes an elastic body and is in contact with the photosensitive drum 110 with a predetermined contact pressure. Further, a blowout prevention sheet 419 is provided in the opening 416d in order to prevent the toner from scattering from below the developing roller 411.

  The developing roller 411 is a semiconductive elastic roller composed of a low-hardness rubber material (silicone, urethane, etc.) or a foamed material in which a conductive agent (carbon or the like) is dispersed, and a combination thereof.

  The stirring member 414 is provided on the upper side opposite to the opening 416d so as to be rotatable in the direction of the arrow R3 about the rotation shaft 414a. Further, in the developing container 416, an agitation region M is formed in which the toner in the developing container 416 and the toner replenished from the toner hopper 510 are agitated and mixed.

  The developing device 410 includes a toner surface detection unit 415 that uses an optical system including a light emitting unit 415a, a transmission window 415b, and a light receiving unit 415c for detecting the height of the toner surface in the stirring region M. The light emitting unit 415a and the light receiving unit 415c are provided on opposite sides of the stirring region M, respectively. The transmission window 415b is provided in the developing container 416 to guide light emitted from the light emitting unit 415a to the stirring region M and further to the light receiving unit 415c. At this time, the two transmission windows 415b are provided on a straight line connecting the light emitting unit 415a and the light receiving unit 415c. The toner surface detecting means 415 arranged in this way measures the light transmission state, that is, the ratio of the light transmission time when the toner surface changes as the stirring member 414 rotates, and the stirring region M The height of the toner surface is detected.

  Below the stirring region M, a supply roller 413 that supplies and collects toner is disposed so as to contact the developing roller 411. The supply roller 413 is an elastic roller made of an elastic foam, and rotates in the reverse direction at the contact point with respect to the developing roller 411.

  The toner is sufficiently agitated by the agitating member 414 in the agitating region M, and then passes through the opening 416 c mainly due to movement by gravity, is conveyed by the supply roller 413, and is supplied to the developing roller 411.

  The developing container 416 is provided with a blade 412 as a regulating member that regulates the toner layer thickness so as to pressurize the developing roller 411. The blade 412 is an elastic regulating member in which an insulating layer 412a is provided on the surface on the contact surface side of the developing roller 411 on a thin plate-like metal plate 412b. The toner supplied onto the developing roller 411 has a layer thickness regulated by the blade 412 and is applied to form a thin layer of toner on the developing roller 411. Further, due to the friction with the surfaces of the developing roller 411 and the blade 412 at this time, the toner is given a sufficient charge to be used for development.

  Thereafter, the toner thin layer on the developing roller 411 is conveyed to a developing region (developing nip) where the photosensitive drum 110 and the developing roller 411 are in contact with the rotation of the developing roller 411. Then, the toner is used for development while being in contact with the photosensitive drum 110. That is, a power source (not shown) is connected to form a developing electric field between the photosensitive drum 110 and the developing roller 411. As a result, the toner on the developing roller 411 is transferred onto the photosensitive drum 110 by the action of the developing electric field, forms a toner image corresponding to the electrostatic latent image on the surface of the photosensitive drum 110, and visualizes the electrostatic latent image.

Further, the toner applied on the developing roller 411 and carried and conveyed to the developing nip does not contribute to the development, and the toner further carried on the developing roller 411 is rubbed by the supply roller 413 by the rubbing by the supply roller 413. 411 is peeled off from above. Thereafter, a part of the removed toner is supplied again onto the developing roller 411 by the supply roller 413 together with the toner newly supplied onto the supply roller 413, and the rest is returned into the developing container 416.

  In this embodiment, the supply roller 413 has two functions as toner supply and recovery means. However, the present embodiment is not limited to this, and the developer supply means, the developer recovery means, Can also be provided separately.

  In this embodiment, the process speed of the image forming apparatus is 150 mm / sec, and the peripheral speed of the developing roller 411 is 225 mm / sec.

  Further, the developing device 410 is configured to be detachable from the image forming apparatus X, and is replaced when reaching a predetermined life (when 30,000 sheets are printed in the A4 size conversion in this embodiment).

  FIG. 3 shows the arrangement of the developing device 410 in the longitudinal direction. In the following description, the vertical direction with respect to the posture (installed state for use) when the developing device 410, that is, the image forming apparatus X is used (operated) (when used) is referred to as the vertical direction. The axial direction of the rotation axis of the developing roller 411 (the direction orthogonal to the recording material conveyance direction) is referred to as a longitudinal direction.

  In this embodiment, as shown in FIG. 3, developer replenishment in which toner is replenished in the agitating chamber 416 b by a toner surface detecting means 415, a partition wall (blocking part, shielding part) 417, and a toner hopper 510 in the longitudinal direction. A toner supply port 418 as a mouth is arranged in order. That is, the partition wall 417 is disposed between the toner surface detection unit 415 and the toner supply port 418.

  The partition wall 417 has a characteristic configuration of the present embodiment, and is provided to prevent the toner supplied from the toner supply port 418 from affecting the light transmission state of the toner surface detection unit 415. .

  In the arrangement of each component, the lower end of the toner surface height range controlled (held) by the toner replenishment control unit of the image forming apparatus based on the detection result of the toner surface detection unit 415 is α (hereinafter referred to as the agent). The upper surface range is referred to as “surface range lower end α” and the upper end is referred to as “β” (hereinafter referred to as agent surface range upper end β). Further, the lowermost point of the optical path width lower end line 415d of the toner surface detecting means 415 in the stirring chamber 416b is γ, the lowermost point of the upper optical path width upper end line 415e in the stirring chamber 416b is δ, And

  At this time, the lower end 417a of the partition wall 417 lowered so as to extend downward from the upper wall (upper part) of the developing container 416 is disposed at the following position. That is, whichever is higher (δ in this embodiment) of the lower end point α of the toner surface range and the lowermost point δ of the optical path width upper end line 415e of the toner surface detecting means 415 in the stirring chamber 416b. Down (low). Furthermore, the upper and lower optical path width lower end line 415d of the toner surface detection means 415 is above (higher) the lowest point γ in the stirring chamber 416b.

  Here, as the toner surface height control means, for example, a CPU or a dedicated electric circuit can be used.

  In the toner hopper 510, a stirring member 514 for loosening the toner in the toner hopper 510 and a replenishing roller 513 for replenishing the toner from the toner hopper 510 to the developing device 410 are arranged. The replenishing roller 513 replenishes the developing device 410 with a certain amount of toner per predetermined driving time in accordance with a replenishment command from the control unit.

  Next, toner amount detection and toner replenishment operations will be described.

  In the present embodiment, the toner surface detecting means 415 has at least two toner surface heights (toner agent surface height) levels (in this embodiment, α and β shown in FIG. Level α and level β).

  The control means provided in the image forming apparatus X basically controls toner replenishment based on the estimated toner usage amount estimated from the image information. Further, the control unit performs control for supplying toner to the developing device 410 by the toner hopper 510 based on the detection result of the toner surface detection unit 415. That is, when the toner surface height is changed by the image forming operation and the toner surface detecting means 415 detects a lower level α of the two agent surface height levels, the toner replenishment control parameter is changed to The supply amount of the supply roller 513 per estimated usage amount is increased. On the other hand, when the toner surface detecting means 415 detects a high level β of the two agent surface height levels due to excessive replenishment, the toner replenishment control parameter is changed again, and the amount per estimated toner usage amount is changed. The driving amount of the supply roller 513 is decreased.

  Thus, the height of the toner surface in the developing container 416 is controlled so as to be maintained within a certain range of α to β shown in FIG.

  In this embodiment, the level α is set to a position higher than the center of the movable range of the stirring member 414, and the level β is set to a position lower than the upper end in the vertical direction of the movable range of the stirring member 414.

  The replenishing roller 513 is disposed vertically above the stirring region M, and is configured to ensure that the replenished toner passes through the stirring region M.

  The replenishing roller 513 is configured so that the toner drops and is replenished in a fine mist to facilitate subsequent mixing with the toner in the developing container.

  With this configuration, as described above, in the stirring region M in the developing device 410, the height of the toner surface is such that the stirring member 414 sufficiently mixes and stirs the toner in the developing device and the replenishing toner. It is controlled to become.

  In addition, after sufficient mixing and stirring, the replenished toner is slowly supplied to the vicinity of the supply roller 413 due to toner consumption due to image formation and movement mainly due to gravity based on the positional relationship between the stirring region M, the supply roller 413, and the blade 412. Is done. Thus, the replenished toner is not supplied to the developing roller 411 in a state where it is not sufficiently mixed with the toner in the developing device 410, and it is possible to prevent the occurrence of density unevenness, fogging, and toner blurring.

  Here, the relationship between the toner surface height and the output (light transmission time) of the toner surface detecting means 415 and the relationship between the toner surface detecting means 415 and the partition 417 between the toner supply port 418 will be described with reference to FIG.

  Since the arrangement of each component of the toner surface detecting means 415 is substantially the same in the conventional configuration and the embodiment, the toner surface detection result in the state without toner replenishment is also substantially the same.

  Here, when the toner is replenished with respect to the conventional configuration, the optical path of the toner surface detecting unit 415 (between 415d and 415e) is particularly obtained when the toner is dropped in the form of a mist with priority on the toner mixing property as described above. ) Was concerned about the fine mist of the replenishing toner. In such a case, the transmission of light is hindered, and output results vary greatly.

  When light transmission is almost eliminated, it is erroneously detected that the toner surface is β or more. The result control means changes the toner replenishment control parameter to decrease the driving amount of the replenishing roller 513 per estimated toner usage amount, and toner replenishment according to the toner usage amount cannot be performed. If the toner replenishment amount is mistakenly reduced, the toner amount in the developing container is excessively reduced, resulting in insufficient stirring and mixing of the toner, resulting in image defects such as density unevenness, fogging, and toner blurring.

  On the other hand, in this embodiment, a partition wall 417 is disposed between the toner surface detecting means 415 and the toner supply port 418. Then, the lower end 417a of the partition wall 417 is the higher one of the toner agent surface range lower end α and the lowest point δ in the stirring chamber 416b of the upper and lower optical path width upper end line 415e of the optical path of the toner surface detecting means 415 (this In the embodiment, it is arranged so as to be lower than δ). Further, the lower end 417a of the partition wall 417 is arranged so as to be above the lowest point γ in the stirring chamber 416b of the lower end line 415d in the vertical direction of the optical path of the toner surface detecting means 415. As a result, the toner surface height can be detected without being affected by the replenishing toner.

  Using the configuration of this example, a durability test of 30,000 sheets, which is the durability life of the developing device, was performed. In the endurance test, the toner surface detection means does not cause erroneous toner surface detection or toner replenishment control, and a good image is maintained without occurrence of density unevenness, fogging, or toner blurring due to poor mixing of replenishment toner on the image. I was able to.

  In order to obtain the effect of this embodiment, the height of the toner surface controlled by the toner replenishment control means and the height of the lower end of the partition wall with respect to the optical path of the toner surface detection means are very important.

Since at least a part of the optical path needs to be separated from the toner supply port side by a partition,
<Condition 1> The lower end 417a of the partition wall 417 needs to be lower than the lowest point δ in the agitating chamber 416b of the upper and lower optical path width upper line 415e of the optical path of the toner surface detecting means 415.

  Here, the case where the lower end α of the toner surface control range is above the lowest point δ in the stirring chamber 416b of the upper and lower optical path width upper line 415e of the optical path of the toner surface detecting means 415 will be described. In this case, during normal operation, toner is present above this δ height, so even if the lower end 417a of the partition wall 417 is between δ, the mist of the replenishing toner does not affect the toner surface detecting means side.

That is, the conditions for suppressing the influence of the replenishing toner on the toner surface detecting means by the partition wall or the toner in the developing container are as follows. That is,
<Condition 2> The lower end 417a of the partition wall 417 is the higher of the toner agent surface range lower end α and the lowermost point δ in the stirring chamber 416b of the upper and lower optical path width upper line 415e of the optical path of the toner surface detecting means 415. This is below (δ in this embodiment).

Further, for the purpose of accurately detecting the height of the toner surface with respect to the stirring member, it is preferable that the toner between the toner surface detecting means side and the toner replenishing port side be freely transferred to some extent, and therefore the range in which the effect of this embodiment can be obtained. Therefore, it is desirable that the lower end 417a of the partition wall 417 is on the upper side. In addition to the condition that the replenishment toner falling on the optical path of the toner surface detection means does not affect,
<Condition 3> The lower end 417a of the partition wall 417 is desirably higher than the lowest point γ in the stirring chamber 416b of the lower end line 415d in the vertical direction of the optical path of the toner surface detection unit 415.

Therefore, regarding the positional relationship of each component having the effect of the present embodiment, the following (1) to (1) to
(3)
(1) A partition wall 417 is disposed between the toner surface detecting means 415 and the toner supply port 418.
(2) The lower end 417a of the partition wall 417 is set to the higher one of the toner agent surface range lower end α and the lowermost point δ in the stirring chamber 416b of the optical path width upper end line 415e of the toner surface detecting means 415 in the optical path. In the embodiment, it is arranged to be lower than δ).
(3) Further, the upper and lower direction optical path width lower end line 415d of the optical path of the toner surface detecting means 415 is disposed above the lowest point γ in the stirring chamber 416b.

  Here, the position of the replenishing roller 513 with respect to the stirring region M is not limited to the vertical upper side of the stirring region M as in this embodiment. That is, the position of the replenishing roller 513 with respect to the stirring region M is such that the toner replenished by the wall of the developing container 416 or the like is guided to the stirring region M and passes through the stirring region M in an obliquely upward direction in the cross-sectional direction. It is also possible to dispose them.

  As described above, according to this embodiment, it is possible to prevent the supply toner from affecting the toner surface detection (influencing the light transmission state), and to perform accurate toner surface detection and toner supply control. Therefore, it is possible to provide a developing device, a process cartridge, and an image forming apparatus that can reduce image defects.

  Next, Example 2 which is another aspect of the present invention will be described. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

The second embodiment is different from the first embodiment mainly in the following points (1) to (4).
(1) The developing device is configured integrally with the photosensitive drum, the charging roller, and the cleaner unit, and is configured as a process cartridge that can be replaced with the image forming apparatus X when a predetermined endurance life is reached.
(2) The image forming apparatus is an inline full-color image forming apparatus in which four (4) process cartridges of yellow (Y), cyan (C), magenta (M), and black (K) are arranged in a line to form an image. .
(3) The developing device is divided into a developing chamber and a stirring chamber, and the stirring chamber is disposed above the developing chamber.
(4) In the developing device, the toner is in the developing chamber, the stirring chamber toner surface detecting portion (the region detected by the toner surface detecting means), the stirring chamber partition wall (the region in the vicinity of the partition wall), the stirring chamber supply port (toner supply port) It must circulate in the order of the neighboring area) and the developing chamber.

  FIG. 5 is a schematic cross-sectional view illustrating the image forming apparatus Y according to the present embodiment.

  The image forming apparatus Y shown in FIG. 5 is a full-color laser beam printer, and an intermediate transfer member 620 that is a second image carrier that multiplex-transfers each color toner image formed on a photosensitive drum and forms a full-color toner image is disposed. Has been.

  The process cartridge PC is configured to be replaceable with respect to the image forming apparatus Y with a predetermined durability life. The image forming apparatus Y includes four process cartridges PC (Y, M, C, and K) that respectively contain four color toners of yellow, magenta, cyan, and black that can be attached to and detached from the image forming apparatus main body.

The process cartridge PC (Y, M, C, K) includes a developing device 420 (Y, M, C, K), a photosensitive drum 120 (Y, M, C, K), and a charging roller 220 (Y, M, K). C, K) and a cleaner unit 720 (Y, M, C, K) are integrally formed. Here, FIG. 6 shows a black (K) process cartridge. The photosensitive drum 120 (Y, M, C, K) constitutes a transfer roller 621 (Y, M, C, K) and a transfer unit, respectively.

  The toner image formed on the surface of the photosensitive drum 120 (Y, M, C, K) is transferred onto the intermediate transfer member 620 according to the arrangement order of the process cartridges PC (Y, M, C, K) of yellow, magenta, cyan, and black. Multiple transfer is performed as a color toner image. The color toner image on the intermediate transfer body 620 is transferred to a recording material conveyed by a feeding roller 920 by a transfer unit 622, and then heated and pressure-fixed by a fixing device (not shown) to be discharged as a full color image. .

  Since the main components in each process cartridge PC are the same as those in the first embodiment, description thereof is omitted. That is, the configuration and operation of the photosensitive drum 120, the developing roller 421 as the developer carrying member, the charging roller 220, the toner surface detecting unit 425, and the like are the same as those of the photosensitive drum 110, the developing roller 411, and the charging roller 210 of the first embodiment. The same as the toner surface detecting means 415 and the like. In the following description, since the process cartridges of four colors of yellow (Y), cyan (C), magenta (M), and black (K) have the same configuration, Y, M, C, and K are omitted. This will be described using reference numerals.

  FIG. 7 is a view showing a toner hopper 520 similar to that of the first embodiment, which is detachably provided in the image forming apparatus. FIG. 7 shows the black (K) toner hopper 520K.

  In the toner hopper 520, a stirring member 524 for loosening the toner in the toner hopper 520 and a supply roller 523 for supplying toner from the toner hopper 520 to the developing device 420 are arranged. The replenishing roller 523 replenishes toner to the developing device 420 according to a replenishment command from the control unit.

  Next, the configuration of the developing device 420 will be described with reference to FIGS.

  In the developing device 420 according to this embodiment, the developing container is divided into a developing chamber 426a and a stirring chamber 426b, and a partition 426g is provided between the developing chamber 426a and the stirring chamber 426b. The agitation chamber 426b is provided with a toner replenishing port 428, an agitation member 424 rotatably supported on the rotation shaft 424a, and a toner surface detecting means 425. Further, a developing roller 421 is provided in the developing chamber 426a.

  At both longitudinal ends of the partition 426g, there are an opening 426f for moving the toner from the stirring chamber 426b to the developing chamber 426a and an opening 426e for moving the toner from the developing chamber 426a to the stirring chamber 426b. Further, in the developing chamber 426a, toner is transported in the longitudinal direction, and an opening 426e is provided in the partition 426g, so that the toner is moved (conveyed) from the developing chamber 426a to the stirring chamber 426b. A conveying screw 429 is provided. Thus, the toner is developed in the developing chamber 426a, the opening 426e, the region detected by the toner surface detecting means 425 in the stirring chamber, the region in the stirring chamber near the partition wall 427, the region in the stirring chamber near the supply port 428, the opening 426f, the developing chamber. It becomes the structure which circulates in order of 426a.

  In this embodiment, the toner surface of the stirring chamber 426b (the toner surface height (agent surface range lower end α to the agent surface range upper end β)) of the stirring chamber 426b with respect to the uppermost point (uppermost portion) 426h of the inner wall surface of the developing chamber 426a. The developing chamber 426a and the agitation chamber 426b are configured so as to be highly controllable. For this reason, when the toner in the developing chamber 426a decreases, the toner can move from the stirring chamber 426b by gravity.

  The developer stirring means has a stirring member 424 and a rotating shaft 424a that rotatably supports the stirring member 424, and is provided in the stirring chamber 426b. The agitating member 424 in the agitating chamber 426b does not particularly have a force for conveying the toner in the longitudinal direction (axial direction of the rotating shaft 424a), but the effect of conditioning the toner surface in the longitudinal direction is high. In actuality, the stirring member 424 adjusts the difference in the height of the toner surface in the longitudinal direction in the stirring chamber 426b, which is generated when the toner transported by the transporting screw 429 in the developing chamber 426a rises toward the stirring chamber 426b. Moves in the longitudinal direction in the stirring chamber 426b. Further, the toner in the agitating chamber 426b is allowed to fall by gravity from the opening 426f due to the decrease in the toner in the developing chamber 426a, and the toner in the agitating member 424 adjusts the difference in the height of the toner surface in the longitudinal direction in the agitating chamber 426b. Moves in the longitudinal direction in the stirring chamber 426b.

  As described above, in the configuration in which the toner circulates in the longitudinal direction, the agitation time can be increased by utilizing the length of the longitudinal direction, but the agitation chamber is further disposed above the developing chamber as described above. It is more effective to reduce the conveying force of the stirring chamber. That is, with such a configuration, it is possible to move the toner in the agitating chamber 426b very slowly and to agitate the toner for a longer time than when the toner is mechanically conveyed. .

  In order to make full use of the advantage of taking a long toner stirring time, the toner replenishing port 428 must be upstream in the circulation direction in the stirring chamber 426b. Accordingly, the toner surface detecting means 425 disposed at the uppermost stream of the stirring chamber 426b and the toner replenishing port 428 are adjacent to each other in order to detect the toner surface reflecting the toner return amount from the developing chamber. Therefore, the toner surface detection unit 425 is easily affected by the replenishment toner (similar to the first embodiment).

Also in this embodiment, regarding the components in the stirring chamber 426b, that is, regarding the positional relationship between the partition wall 427, the lower end 427a of the partition wall 427, the toner surface range lower end α, the lowest point δ, and the lowest point γ, The following (1) to (3) are obtained. Here, the lowest point δ is the lowest point in the stirring chamber 426b of the upper and lower optical path width line 425e of the optical path of the toner surface detecting means 425, and the lowest point γ is the optical path of the toner surface detecting means 425. This is the lowest point in the agitating chamber 426b of the vertical path width lower end line 425d.
(1) A partition wall 427 is disposed between the toner surface detecting means 425 and the toner supply port 428.
(2) The lower end 427a of the partition wall 427 is set to the higher one of the toner agent surface range lower end α and the lowermost point δ in the stirring chamber 426b of the upper and lower optical path width upper line 425e of the toner surface detecting means 425. In the embodiment, it is arranged to be lower than δ).
(3) Further, the upper and lower optical path width lower end line 425d of the optical path of the toner surface detecting means 425 is disposed above the lowest point γ in the stirring chamber 426b.
As a result, the toner surface height can be detected without being affected by the replenishing toner.

  Using the configuration of this example, a durability test of 30,000 sheets, which is the durability life of the developing device, was performed. In the endurance test, the toner surface detection means does not cause erroneous toner surface detection or toner replenishment control, and maintains a good image without occurrence of density unevenness, fogging, and toner blurring due to poor mixing of replenishing toner on the image. I was able to.

  As described above, according to this embodiment, the influence of the replenishment toner on the toner surface detection can be prevented, and accurate toner surface detection and toner replenishment control can be performed. Therefore, it is possible to provide a developing device, a process cartridge, and an image forming apparatus that can reduce image defects.

1 is a schematic cross-sectional view of an image forming apparatus according to Embodiment 1 of the present invention. 1 is a cross-sectional view of main parts of a developing device and a toner hopper according to Embodiment 1 of the present invention. It is a figure which shows arrangement | positioning of the longitudinal direction of the developing device which concerns on Example 1 of this invention. In Embodiment 1 of the present invention, it is a diagram for explaining the relationship between the toner surface height and the output (light transmission time) of the toner surface detection means, and the relationship between the partition wall between the toner surface detection means and the toner supply port. It is a schematic sectional drawing of the image forming apparatus which concerns on Example 2 of this invention. It is a schematic sectional drawing of the process cartridge which concerns on Example 2 of this invention. FIG. 6 is a schematic cross-sectional view of a toner hopper according to Embodiment 2 of the present invention. FIG. 6 is a cross-sectional view of a main part of a developing device and a toner hopper according to Embodiment 2 of the present invention. FIG. 6 is a cross-sectional view of a main part of a developing device and a toner hopper according to Embodiment 2 of the present invention. It is a schematic sectional drawing which shows an example of schematic structure of the conventional image forming apparatus.

Explanation of symbols

110, 120 Photosensitive drum (image carrier)
410, 420 Development device 411 Development roller (developer carrier)
412 Blade 413 Supply roller 414, 424 Stirring member (developer stirring means)
415, 425 Toner surface detection means (agent surface detection means)
415a, 425a Light emitting portion 415b, 425b Transmission window 415c, 425c Light receiving portion 416, 426 Developing container 416a Developing chamber 416b Stirring chamber 416c, 416d, 426c, 426d, 426e, 426f Opening portion 426g Developing chamber-stirring chamber partition 417, 427 Partition wall 418, 428 Toner supply port (Developer supply port)
429 conveying screw (developer conveying means)
510, 520 toner hopper (developer supply means)
P Recording material PC Process cartridge X, Y Image forming device

Claims (12)

A developer supply port through which developer is supplied by the developer supply means;
Developer agitation means movable to mix the developer replenished from the developer replenishing port and the developer present in the developing device;
Optical agent level detecting means for irradiating light toward the vicinity of the developer agitating means and detecting the developer level in the vicinity of the developer agitating means according to the light transmission state;
With
In the developing device for developing the electrostatic latent image formed on the image carrier with the developer replenished by the developer replenishing unit based on the detection result of the agent surface detecting unit,
A partition wall provided between the developer replenishing port and the agent surface detecting unit, and preventing a developer replenished from the developer replenishing port from affecting the light transmission state of the agent surface detecting unit. A developing device. In the posture when using the developing device,
The partition wall is provided so as to extend downward from the upper part of the developer container provided with the developer stirring means,
The height of the lower end of the partition wall is
The lowermost point of the positions that the upper end of the optical path width in the vertical direction of the light path of the light irradiated by the agent surface detecting means takes in the developing container,
Or
Of the vertical region of the partition wall, the lowest point of the developer surface height of the developer held by the developer replenishing means being replenished by the developer,
The developing device according to claim 1, wherein one of the two is lower than the higher one.   The height of the lower end of the partition wall is higher than the lowest point of the positions taken in the developing container by the lower end of the optical path width in the vertical direction in the optical path of the light irradiated by the agent surface detecting means. The developing device according to claim 2, wherein: A developer supply port through which developer is supplied by the developer supply means;
Developer agitation means movable to mix the developer replenished from the developer replenishing port and the developer present in the developing device;
Optical agent level detecting means for irradiating light toward the vicinity of the developer agitating means and detecting the developer level in the vicinity of the developer agitating means according to the light transmission state;
With
In the developing device for developing the electrostatic latent image formed on the image carrier with the developer replenished by the developer replenishing unit based on the detection result of the agent surface detecting unit,
A stirring chamber including the developer replenishing port, the developer stirring means, and the agent level detection means;
A developing chamber including a developer carrier for carrying and conveying the developer;
A developer conveying means provided in the developing chamber for conveying the developer in the developing chamber to the stirring chamber;
Provided between the developer replenishing port and the agent surface detecting means in the stirring chamber, the developer replenished from the developer replenishing port affects the light transmission state of the agent surface detecting unit. Prevent the partition wall,
With
An area in which the developer in the developing chamber conveyed by the developer conveying means is detected by the agent level detecting means in the stirring chamber, an area in the vicinity of the partition in the stirring chamber, and the developer replenishment in the stirring chamber A developing device characterized in that it is configured to circulate in the order of the area near the mouth and the developing chamber. In the posture when using the developing device,
The partition is provided to extend downward from the upper part of the stirring chamber,
The height of the lower end of the partition wall is
The lowest point of the positions taken by the upper end of the optical path width in the vertical direction in the optical path of the light irradiated by the agent surface detecting means, in the stirring chamber,
Or
Of the vertical region of the partition wall, the lowest point of the developer surface height of the developer held by the developer replenishing means being replenished by the developer,
The developing device according to claim 4, wherein one of the two is lower than the higher one.   The height of the lower end of the partition wall is higher than the lowest point among the positions taken by the lower end of the optical path width in the vertical direction in the optical path of the light irradiated by the agent surface detecting means. The developing device according to claim 5.   The developing chamber and the agitation chamber are configured so that the developer surface height of the developer in the agitation chamber is higher than the uppermost part of the inner wall surface in the development chamber. The developing device according to any one of 4 to 6. The developer stirring means includes a stirring member that stirs the developer, and a rotating shaft that rotatably supports the stirring member,
The developing device according to claim 7, wherein the agitating member does not have a conveyance force for conveying the developer in an axial direction of the rotation shaft.   The developing device according to any one of claims 1 to 8, wherein the developer has a shape factor SF-1 of 100 to 140 and a shape factor SF-2 of 100 to 120.   The developing device according to claim 9, wherein a part or all of the developer is formed by a polymerization method.   11. A process cartridge comprising at least the developing device according to claim 1 and configured to be detachable from an image forming apparatus main body. An image forming apparatus comprising: an image carrier; and the developing device according to claim 1 that performs a developing action on the image carrier.

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