JP6659082B2 - Image forming device - Google Patents

Description

  The present invention relates to a cartridge, a process cartridge including a developing device, and an image forming apparatus. Here, the developing device has at least a developer carrying member that carries the developer. Further, the developing device may include a frame for storing the developer, a transport member for transporting the developer, and the like. The process cartridge has at least an image carrier that carries the developer image. In particular, a unit in which an image carrier and a process means acting on the image carrier are integrated is called a process cartridge. The image forming apparatus is an apparatus that forms an image on a recording material, and particularly relates to an image forming apparatus using an electrophotographic method.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus, a cleanerless system (toner recycling system) has been proposed from the viewpoint of simplifying the apparatus configuration and eliminating waste. This cleaner-less system has a configuration in which a dedicated drum cleaner, which is a surface cleaning unit after a transfer process of a photoconductor, is eliminated in a transfer type image forming apparatus. Then, the transfer residual toner on the photoreceptor after the transfer process is cleaned by a developing device, removed from the photoreceptor, and collected by the developing device.

  In particular, performing cleaning while performing development with a developing device is referred to as simultaneous development cleaning. Simultaneous development cleaning refers to a fogging bias (fogging potential difference Vback, which is a potential difference between a DC voltage applied to the developing device and a surface potential of the photoreceptor) at the time of development after the next step. It is a method of collecting by. According to this method, since the transfer residual toner is collected in the developing device and reused after the next process, waste toner can be eliminated, and troublesome maintenance can be reduced. In addition, since the cleaner is not used, there is no need for a separate cleaner mechanism, so that there is a great advantage in terms of space, and the image forming apparatus can be significantly reduced in size (Patent Documents 1 to 3).

  Here, when the cleaner-less system is employed, when the toner is recycled, there is a possibility that foreign matter such as powdered paper may be mixed into the developing device, and an image defect may occur due to the foreign matter. For example, there is a streak-like image defect that occurs when dust paper or foreign matter is caught between the regulating blade and the developing sleeve and a uniform toner layer is disturbed. In addition, the development of the paper powder with the toner may cause black spots on a white background of the paper, or conversely, white spots on a printed portion.

In view of this, a one-component magnetic contact developing system has been proposed as a developing device used in a cleanerless system (Patent Document 1). In this method, a magnetic developer (magnetic toner) is carried on a developing sleeve (developer carrier) including a magnetic field generating means, and development is performed by bringing the magnetic developer (magnetic toner) into contact with the surface of the photoconductor.
In such a developing device, the toner is supplied to the developing sleeve by using a magnetic toner and a magnetic force. Therefore, the toner can be supplied to the developing sleeve preferentially over the paper powder having no magnetic force. For this reason, the effect of paper dust on an image is less likely to occur than in a cleanerless system using a non-magnetic contact developing method.

On the other hand, a cleanerless system employing a contact charging method using a charging roller has been proposed (Patent Document 2). As a problem when using the contact charging method in the cleanerless system, there is a charging failure due to toner adhering to a charging roller serving as a charging member. As a method for reducing the adhesion of the toner to the charging member, it is known to drive the charging member so as to provide a peripheral speed difference with the photosensitive drum. It is also known to provide a light neutralizing means from the viewpoint of stability of the charging step and memory removal.

Japanese Patent No. 4510493 JP-A-2004-354978 Japanese Patent No. 4630707

However, in recent years, users have been diversified, and the types of paper used have also been diversified. Among various types of paper, there may be paper in which a large amount of paper dust is emitted. In addition, there may be paper on which other foreign substances appear in addition to paper dust.
In a configuration in which a peripheral speed difference is provided between the charging member and the photosensitive drum to reduce the influence of foreign matter as in the prior art, the toner or paper powder scraped off by the peripheral speed difference between the charging member and the photosensitive drum scatters, and the charging member is scattered. There is a possibility that the light neutralizing means existing below the surface may be soiled.

Therefore, the present invention
An image carrier;
A transfer unit that transfers the developer image formed on the image bearing member onto a transfer material,
A developer is supplied to the image carrier on which a contact charging member for charging the surface of the image carrier is disposed, and after a developer image formed on the image carrier is transferred to a transfer-receiving material, Having a developing device for collecting the developer remaining on the image carrier,
The developing device includes:
A developer carrier that carries the developer on the surface,
A regulating member that regulates the layer thickness of the developer that is in contact with the developer carrier and that is carried on the surface of the developer carrier,
A developing chamber frame forming a developing chamber having an opening provided with the developer carrier and the regulating member;
A storage chamber frame that forms a storage chamber that stores the developer,
A transfer member provided in the storage chamber and configured to transfer the developer stored in the storage chamber to the development chamber through the opening;
The contact charging member is disposed downstream of the light removing unit in the rotation direction of the image carrier, and a peripheral speed difference is generated between the surface of the contact charging member and the surface of the image carrier. Driven,
The contact portion of the image carrier with the contact charging member is located vertically below the light neutralizing unit,
The bottom of the developing chamber is located vertically above the bottom of the storage chamber,
The developing contact portion of the developer carrier that the restricting member contacts is located immediately above the opening in the vertical direction,
The regulating member has a convex portion that comes into contact with the developer carrier, and a tip portion that protrudes more upstream than the convex portion in the rotation direction of the developer carrier, and a surface of the developer carrier. A gap is formed between the developer carrying member and the leading end by the convex portion and the leading end, and a gap between the leading end facing the surface of the developer carrying body in the gap. It is an object of the present invention to provide an image forming apparatus, wherein a height of the protrusions in a direction toward the surface is 200 to 400 μm.

Also, the present invention
An image carrier;
A transfer unit that transfers the developer image formed on the image bearing member onto a transfer material,
A developer is supplied to the image carrier on which a contact charging member for charging the surface of the image carrier is disposed, and after a developer image formed on the image carrier is transferred to a transfer-receiving material, Having a developing device for collecting the developer remaining on the image carrier,
The developing device includes:
A developer carrier that carries the developer on the surface,
A regulating member that regulates the layer thickness of the developer that is in contact with the developer carrier and that is carried on the surface of the developer carrier,
A developing chamber frame forming a developing chamber having an opening provided with the developer carrier and the regulating member;
A storage chamber frame that forms a storage chamber that stores the developer,
A transfer member provided in the storage chamber and configured to transfer the developer stored in the storage chamber through the opening to the development chamber,
The contact charging member is disposed downstream of the light removing unit in the rotation direction of the image carrier, and a peripheral speed difference is generated between the surface of the contact charging member and the surface of the image carrier. Driven, and the contact portion of the image carrier with the contact charging member is, with respect to a straight line connecting the vertex of the image carrier and the rotation center when viewed in the rotation axis direction of the image carrier. , Is located on the opposite side to the light neutralization means,
The bottom of the developing chamber is located vertically above the bottom of the storage chamber,
The developing contact portion of the developer carrier that the restricting member contacts is located immediately above the opening in the vertical direction,
The regulating member has a convex portion that comes into contact with the developer carrier, and a tip portion that protrudes upstream of the convex portion in the rotation direction of the developer carrier, and has a surface that faces the developer carrier. A gap is formed between the developer carrier and the tip by the protrusion and the tip, and the gap between the developer carrier and the tip is opposite to the surface of the developer carrier facing the surface of the developer carrier in the gap. It is an object of the present invention to provide an image forming apparatus, wherein the height of the projections along the direction toward the surface is 200 to 400 μm.

  ADVANTAGE OF THE INVENTION According to this invention, the dirt of the optical static elimination means by paper dust, toner, etc. can be reduced.

1 is a schematic cross-sectional view illustrating a configuration of a developing device according to a first exemplary embodiment. 1 is a schematic cross-sectional view illustrating an entire configuration of an image forming apparatus according to a first embodiment. FIG. 4 is a diagram illustrating the movement of toner in the developing device according to the first exemplary embodiment. FIG. 4 is a view for explaining movement of paper dust in the first embodiment. Schematic diagram showing the contact state between the regulating blade and the developing sleeve and the distribution of the contact pressure Schematic diagram showing the contact state between the regulating blade and the developing sleeve and the distribution of the contact pressure 3 is a schematic cross-sectional view illustrating an entire configuration of an image forming apparatus according to a third embodiment. Schematic cross-sectional view showing the structure of the charging roller and the light dividing photoelectric means according to Embodiment 3 Schematic sectional view of an optical dividing photoelectric means according to Embodiment 3 Schematic cross-sectional view showing the structure of the charging roller and the light dividing photoelectric means according to the fourth embodiment FIG. 4 is a schematic cross-sectional view showing the configurations of Examples 3 and 4 and a comparative example. FIG. 2 is a schematic cross-sectional view illustrating a configuration of a conventional developing device.

  Embodiments for carrying out the present invention will be illustratively described in detail below based on embodiments with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment should be appropriately changed depending on the configuration of the apparatus to which the invention is applied and various conditions. That is, the scope of the present invention is not intended to be limited to the following embodiments.

(Example 1)
<Outline of Overall Configuration of Image Forming Apparatus>
First, with reference to FIG. 2, an outline of the entire configuration of the image forming apparatus according to the present embodiment will be described. FIG. 2 is a schematic sectional view illustrating the entire configuration of the image forming apparatus according to the present embodiment. In this embodiment, a monochrome laser printer using a transfer type electrophotographic process will be described as an image forming apparatus.

  The image forming apparatus according to the present embodiment includes, as main components, a photosensitive drum 1 as an image carrier, a charging roller 2 as a charging unit, a developing device 3, a laser beam scanner 4 as an exposure unit, and a transfer as a transfer member. A roller 5 and a fixing device 6 are provided. Further, the image forming apparatus according to the present embodiment has a configuration in which a process cartridge in which the photosensitive drum 1, the charging roller 2, the developing device 3, and the like are formed into a cartridge is detachably provided.

  The photosensitive drum 1 of this embodiment is an OPC photosensitive member having a negative polarity of φ24 mm. The photosensitive drum 1 is provided so as to be rotatable at a peripheral speed (process speed, printing speed) of 100 mm / sec in the direction of arrow R1 in FIG.

  The charging roller 2 charges the surface of the photosensitive drum 1. The charging roller 2 is a conductive elastic roller, and has a core 2a and a conductive elastic layer 2b covering the core 2a. The charging roller 2 is in pressure contact with the photosensitive drum 1 with a predetermined pressing force. A portion (contact portion) of the surface of the photosensitive drum 1 which is pressed against the charging roller 2 is referred to as a charging portion c. A charging nip is formed by the charging portion c and a contact portion of the charging roller 2 with the photosensitive drum 1. Further, the charging roller 2 is driven to rotate as the photosensitive drum 1 rotates.

  Further, the image forming apparatus according to the present embodiment has a charging power source for applying a charging bias to the charging roller 2. The charging power supply applies a DC voltage to the metal core 2 a of the charging roller 2. This DC voltage is set to a value such that the potential difference between the surface potential of the photosensitive drum 1 and the potential of the charging roller 2 is equal to or higher than the discharge starting voltage. Specifically, a DC voltage of -1300 V is charged as a charging bias. Applied from power supply. At this time, the surface potential (dark portion potential) of the photosensitive drum 1 is uniformly charged to -700V.

  The laser beam scanner 4 has a laser diode, a polygon mirror, and the like. The laser beam scanner 4 outputs laser light L whose intensity is modulated in accordance with a time-series electric digital pixel signal of target image information, and scans and exposes the surface of the photosensitive drum 1 charged with the laser light L. . When the entire surface of the photosensitive drum 1 is exposed by the laser beam L, the laser power of the laser beam scanner 4 is adjusted so that the surface potential of the photosensitive drum 1 becomes -150V.

  The developing device 3 has a developing chamber 301 formed by a first frame 3A and a toner storage chamber 300 formed by a second frame 3B. As shown in FIG. 1, the first frame 3A has a portion 3A1 having an opening lower end portion Y described later, a portion 3A2 having an opening upper end portion X described later, and a portion 3A3. The second frame 3B includes a portion 3B1 located outside the portion 3A1 of the first frame 3A, a portion 3B2 forming the majority of the toner storage chamber 300, and an outside of the portion 3A3 of the first frame 3A. And a portion 3B3 located at The developing chamber 301 is provided with a developing sleeve 31 as a developer carrier and a regulating blade 33 as a regulating member. The toner storage chamber 300 stores a magnetic toner t as a magnetic developer. The configuration of the developing device 3 will be described later in detail.

The magnetic toner t is attracted to the surface of the developing sleeve 31 by the magnetic force of a magnet roller 32 which is a magnetic field generating means included in the developing sleeve 31. The magnetic toner t has a certain frictional charge. Then, the magnetic toner t develops an electrostatic latent image on the photosensitive drum 1 (on the image carrier) in the developing section a by the developing bias applied between the developing sleeve 31 and the photosensitive drum 1 by the developing bias applying power supply. Image. In this embodiment, the developing bias is set to -350V. The developing unit a is a developing sleeve 3 on the surface of the photosensitive drum 1.
1 is a region where the magnetic developer is supplied by the developing sleeve 31.

A transfer roller 5 having a medium resistance is provided as a contact transfer unit, and is provided so as to be pressed against the photosensitive drum 1 with a predetermined pressure. A portion (contact portion) of the surface of the photosensitive drum 1 that is pressed against the transfer roller 5 is referred to as a transfer portion b. A transfer nip is formed by the transfer portion b and a contact portion of the transfer roller 5 with the photosensitive drum 1. The transfer roller 5 of this embodiment is composed of a metal core 5a and a medium-resistance foam layer 5b that covers the metal core 5a, and has a roller resistance value of 5 × 10 ⁸ Ω. Then, a voltage of +2.0 kV was applied to the cored bar 5a, and the toner image formed on the photosensitive drum 1 as a developer image was transferred to paper P as a transfer material.

  The fixing device 6 fixes the toner image on the paper P by heating and pressing the paper P on which the toner image has been transferred through the transfer nip. Thereafter, the paper P on which the toner image is fixed is discharged out of the apparatus.

<Image forming process>
Next, an outline of the image forming process will be described with reference to FIG. First, when a print signal is input to the controller of the image forming apparatus main body, the image forming apparatus starts an image forming operation. Then, at a predetermined timing, each drive section starts to move and a voltage is applied. The rotating photosensitive drum 1 is uniformly charged by the charging roller 2. The uniformly charged photosensitive drum 1 is exposed by the laser beam L from the scanner unit 4, and an electrostatic latent image is formed on the surface. After that, the electrostatic latent image is supplied with toner (developer) by the developing roller 31 and is visualized as a toner image (developer image).

  On the other hand, the paper P is separated and fed from the transfer material storage unit 70 by the transfer material supply unit 71, and synchronized with the timing of forming the toner image on the photosensitive drum 1, the paper P is transferred to the transfer area a. Send out. Thus, the visualized toner image on the photosensitive drum 1 is transferred to the paper P by the action of the transfer roller 5. The paper P as the transfer material on which the toner image has been transferred is transported to the fixing device 6. Here, the unfixed toner image on the paper P is fixed on the paper P by heat and pressure. Thereafter, the paper P is discharged out of the apparatus by a discharge roller or the like.

<Cleanerless system>
Next, the cleanerless system in the present embodiment will be described in detail. In the present embodiment, a so-called cleaner-less system is employed in which a cleaning member for removing untransferred residual toner remaining on the photosensitive drum 1 from the photosensitive drum 1 is not provided.

  The transfer residual toner remaining on the photosensitive drum 1 after the transfer process is charged to a negative polarity similarly to the photosensitive drum 1 by the discharge in the gap before the charging nip. At this time, the surface of the photosensitive drum 1 is charged to -700V. The transfer residual toner charged to the negative polarity passes through the charging nip without adhering to the charging roller 2 due to a potential difference relationship (photosensitive drum surface potential = −700 V, charging roller potential = −1300 V).

  The transfer residual toner that has passed through the charging nip reaches a laser irradiation position d on the surface of the photosensitive drum 1 where the laser light is irradiated. Since the transfer residual toner is not so large as to block the laser beam of the exposure unit, it does not affect the process of forming an electrostatic latent image on the photosensitive drum 1. Of the toner that has passed the laser irradiation position d, the toner in the non-exposed portion (the surface of the photosensitive drum that has not been irradiated with the laser) is collected by the developing sleeve 31 by electrostatic force in the developing portion a.

On the other hand, of the toner that has passed through the laser irradiation position d, the toner in the exposed portion (the surface of the photosensitive drum that has been irradiated with the laser) remains on the photosensitive drum 1 without being collected electrostatically.
However, some toner may be collected by physical force due to a difference in peripheral speed between the developing sleeve 31 and the photosensitive drum 1. The toner remaining on the photosensitive drum 1 without being transferred to the paper P in this manner is generally collected by the developing device 3. Then, the toner collected in the developing device 3 is mixed with the toner remaining in the developing device 3 and used.

(Compatible with charging roller contamination)
In this embodiment, the following two configurations are employed in order to allow the transfer residual toner to pass through the charging nip without adhering to the charging roller 2.

  First, as shown in FIG. 2, a light removing member 8 is provided between the transfer roller 5 and the charging roller 2 in the rotation direction of the photosensitive drum. The light neutralizing member 8 optically neutralizes the surface potential of the photosensitive drum 1 after passing through the transfer nip in order to perform stable discharge at the charging nip. By setting the potential of the photosensitive drum 1 before charging to about -150 V in the entire longitudinal direction by the light removing member 8, uniform discharge can be performed at the time of charging, and the transfer residual toner can be made to have a uniform negative polarity. . As a result, the transfer residual toner passes through the charging nip.

  Second, the charging roller 2 is driven and rotated with a predetermined peripheral speed difference from the photosensitive drum 1. As described above, most of the toner has a negative polarity due to the discharge, but some toner that has not been completely converted to the negative polarity remains, and this toner may adhere to the charging roller 2 at the charging nip. Therefore, by rotating the charging roller 2 and the photosensitive drum 1 while providing a predetermined peripheral speed difference, it is possible to make such toner negative by sliding friction between the photosensitive drum 1 and the charging roller 2. Become. This has the effect of reducing the adhesion of toner to the charging roller 2. In this embodiment, a charging roller gear is provided on the core metal 2a of the charging roller, and the charging roller gear is engaged with a drum gear provided at an end of the photosensitive drum. Therefore, as the photosensitive drum 1 rotates, the charging roller 2 also rotates. The peripheral speed of the surface of the charging roller 2 is set to be 115% of the peripheral speed of the surface of the photosensitive drum 1. That is, the peripheral speed of the surface of the charging roller is set faster than the peripheral speed of the surface of the photosensitive drum. The peripheral speed difference in the present embodiment is 15%, but is preferably in the range of 5% to 20%. If the peripheral speed difference is too large, the shaving amount of the roller increases, and the service period of the roller is shortened.

  In such a cleanerless system, particularly in a configuration in which the photosensitive drum 1 is directly transferred to paper P such as paper as in the present embodiment, paper dust or the like coming out of the paper adheres to the surface of the photosensitive drum 1, and Paper dust may be collected in the developing device 3. When the paper dust collected by the developing device 3 is caught between the regulating blade 33 and the developing sleeve 31 in the regulating portion e, the paper dust on the developing sleeve 31 is disturbed. Further, the paper powder that has passed through the regulating portion e and coated on the developing sleeve 31 together with the toner may not be charged to the normal charging polarity or may be aggregated with the toner. For this reason, black spots appear on the photosensitive drum 1 in portions that do not need to be developed, and conversely, when developed together with toner, only the paper dust portions do not appear in color and appear as white spots. Here, the regulating portion e is a portion (developing contact portion) of the developing sleeve 31 that the regulating blade 33 contacts.

  In the present embodiment, since paper is used as the material to be transferred, a problem caused by paper dust will be described, but the present invention is not limited to this. For example, an effect can be obtained by employing the configuration of the present invention even with respect to a problem caused by a foreign substance such as a powder generated when a plastic sheet or the like is used as a transfer material.

<Description of developing device>
Next, with reference to FIG. 1, details of the developing device according to the present embodiment for reducing the problems that occur when the above-described cleanerless system is employed will be described. FIG. 1 is a schematic sectional view illustrating the configuration of the developing device according to the present embodiment.

  As shown in FIG. 1, the developing device 3 includes a toner storage chamber 300 for storing toner therein, and a developing chamber 301 having a developing sleeve 31.

  The developing sleeve 31 is formed by forming a conductive elastic layer having a thickness of about 500 μm on the outer periphery of a non-magnetic sleeve as a supporting portion formed of an aluminum or stainless steel pipe. The developing sleeve 31 is rotatably supported by the developing chamber 301 in the direction of arrow R2. The developing sleeve 31 is formed to have an outer diameter of Φ11 mm and a surface roughness of 1.5 to 4.5 μm on average according to JIS standard Ra. The developing sleeve 31 is pressed in the direction of the photosensitive drum 1 so as to contact the photosensitive drum 1. The developing sleeve 31 is provided with rollers for regulating the amount of intrusion at both ends in the longitudinal direction (axial direction). The rollers are brought into contact with the photosensitive drum 1 so that the developing sleeve 31 and the surface of the photosensitive drum 1 are brought into contact with each other. Is set to a predetermined value.

  A developing sleeve gear is fixed to one end of the developing sleeve 31, and a driving force is transmitted to the developing sleeve gear from a driving source of the main body of the image forming apparatus via a plurality of gears. Is driven to rotate. The surface speed of the developing sleeve 31 rotates forward with a speed difference of 140% with respect to the surface peripheral speed of the photosensitive drum 1. The surface of the developing sleeve 31 has an appropriate surface roughness so that a desired amount of toner can be carried and transported.

  A magnet 32 is provided inside the developing sleeve 31. As the magnet 32, a four-pole magnet roll having a cylindrical shape and N poles and S poles alternately arranged in the circumferential direction was used. The four poles are the developing pole facing the photosensitive drum 1, the regulating pole facing the regulating blade 33, the supply pole for supplying the toner in the developing chamber 301 to the developing sleeve 31, and the leakage of the facing part of the toner blowing prevention sheet S. There are four prevention poles. The magnetic flux density of each pole is 70 mT, which is the strongest of the regulating pole, and about 50 mT for the other poles. Unlike the case where the developing sleeve 31 rotates in the direction of the arrow R <b> 2, the magnet 32 is fixedly disposed inside the developing sleeve 31.

  The regulating blade 33 is a plate-like member made of, for example, SUS or phosphor bronze having a thickness of about 100 μm. The base end of the regulating blade 33 is fixed to a supporting metal plate. The contact is made at a predetermined pressure. The contact is performed so that the contact force is about 20 gf / cm to 40 gf / cm (the contact load per 1 cm in the longitudinal direction of the developing sleeve 31). In the first embodiment, the free end portion 33 a of the regulating blade 33 is in contact with the developing sleeve 31.

  The regulating blade 33 regulates the thick layer of the toner attracted to the surface of the developing sleeve 31 by the magnetic force of the magnet 32. The toner carried on the surface of the developing sleeve 31 is given an appropriate charge by frictional charging due to rubbing between the developing sleeve 31 and the regulating blade 33 when the thickness of the toner is regulated by the regulating blade 33, and furthermore, the photosensitive material is exposed to light. The drum 1 is transported to a region facing the developing unit a. At this time, a developing bias (−350 V) is applied to the developing sleeve 31 from a DC power supply. In the developing section a, the toner on the developing sleeve 31 electrostatically adheres to the electrostatic latent image formed on the surface of the photosensitive drum 1 due to the potential difference between the surface of the photosensitive drum 1 and the potential of the developing sleeve 31. Thus, the electrostatic latent image is developed as a toner image.

The toner conveying member 34 is rotatably disposed in the toner accommodating chamber 300 (accommodating chamber), loosens the toner in the toner accommodating chamber 300, and conveys the toner to the developing chamber 301. As shown in FIG. 1, the toner conveying member 34 includes a shaft rod member 34a with a backup made of a resin material and a PPS film sheet 34b. Further, as shown in FIG. 1, the regulating portion e is provided vertically above the axial center of the toner conveying member 34. And it rotates in the direction of arrow R4 in FIG. The driving force for rotating the toner conveying member 34 is generally used, for example, by lowering the developing sleeve gear to an appropriate rotational speed by a gear train.

In this embodiment, a negatively chargeable magnetic one-component toner is used as the toner. This toner has a binder resin (styrene n-butyl acrylate copolymer) 100 parts by weight, magnetic particles 80 parts by weight as a main component, and a wax or the like included therein. The average particle size is 7.5 μm. is there. 1.2 parts by weight of fine silica powder is used as an external additive. Such toner, when used in the developing device 3 of the above configuration, the toner coat amount on the developing sleeve 31 becomes about ^{0.4mg / cm 2 ~0.9mg / cm 2} .

  Here, the weight average particle size of the toner will be described. As a measuring device, a Coulter Counter TA-II type (manufactured by Coulter Co., Ltd.) is used, and a 1% NaCl aqueous solution is adjusted using primary grade sodium chloride as an electrolytic solution. As a measuring method, 0.1 to 0.5 ml of a surfactant is added as a dispersant to 100 to 150 ml of the above-mentioned electrolytic solution, and 2 to 20 ml of a measurement sample is further added. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment using an ultrasonic disperser, and the particle size distribution is measured by the above-mentioned Coulter counter using a 100 μm aperture as an aperture based on the number. Thereby, the weight average particle size is determined.

  Further, the toner used preferably has a cohesion degree of 40 or less before use and 55 or less throughout the use period. The method for measuring the degree of aggregation is shown below.

(1) Measurement of toner aggregation degree The toner aggregation degree was measured using a powder tester (manufactured by Hosokawa Micron Corporation). Three layers of 200 mesh (opening 77 μm, wire diameter 50 μm), 373 mesh (opening 38 μm, wire diameter 30 μm), and 635 mesh (opening 20 μm, wire diameter 20 μm) are stacked in order from the top on a powder tester. I set it. Then, 2 g of the weighed sample was gently placed on the sieve, and vibration was applied at an amplitude of 1.5 mm for 5 seconds, the weight of the toner remaining on each sieve was measured, and the toner aggregation degree was calculated according to the following equation. .

  Here, the amount of the weighed sample is K, the amount of toner on the upper mesh is L, the amount of toner on the middle mesh is M, and the amount of toner on the lower mesh is N. At this time, if X = L / K, Y = M / K × 0.6, and Z = N / K × 0.2, the toner aggregation degree (%) is represented by the following (Equation 1).

  The toner having high fluidity has a small amount of toner remaining on the 200 mesh, a large amount of toner remaining on the lower mesh, and has a low aggregation degree.

(2) Average Circularity of Toner The toner used is preferably not a pulverized toner but a polymerized toner having an average circularity of 0.93 or more. The method of measuring the circularity is described below.

The circularity of the toner in this embodiment is used as a simple method for quantitatively expressing the shape of the particles. In this embodiment, a flow-type particle image analyzer FPIA-1 manufactured by Toa Medical Electronics Co., Ltd.
The particle shape is measured using 000, and the circularity is determined by the following (Equation 2). Further, as shown by (Equation 3), a value obtained by dividing the measured total circularity of all particles by the total number of particles is defined as an average circularity.

  The measuring device used in this example, "FPIA-1000", calculates the circularity of each particle, and then calculates the average circularity. Divided into For example, 0.400 to less than 0.410, 0.410 to less than 0.420,... 0.990 to less than 1.000, and 1.000 to less than 0.400 and less than 0.410 at circular intervals of 0.400 to 1.000. Is divided into 61 divided ranges. Then, the average circularity is calculated using the center value and the frequency of the division points.

  The difference between each value of the average circularity calculated by this calculation method and each value of the average circularity calculated by the above-described calculation formula that directly uses the circularity of each particle is extremely small, and is substantially small. It is negligible. Therefore, in the present embodiment, for the reason of data handling such as shortening of the calculation time and simplification of the calculation formula, the concept of the calculation formula directly using the circularity of each particle described above is used. This modified calculation method is used.

  The circularity in the present embodiment is an index indicating the degree of unevenness of the particles, and is 1.000 when the particles are perfectly spherical, and the circularity becomes smaller as the surface shape becomes more complicated. As a specific method of measuring the circularity, about 5 mg of the toner is dispersed in 10 ml of water in which about 0.1 mg of a nonionic surfactant is dissolved to prepare a dispersion, and ultrasonic waves (20 kHz, 50 W) are applied to the dispersion. Irradiate for 5 minutes. Then, with the concentration of the dispersion liquid being 5,000 to 20,000 / μl, the circularity distribution of the particles having a circle equivalent diameter of 3 μm or more is measured using the above-mentioned flow type particle image measuring device.

  The outline of the measurement is described in the catalog of FPIA-1000 (June 1995 version) issued by Toa Medical Electronics Co., Ltd., the operation manual of the measurement apparatus and Japanese Patent Application Laid-Open No. 8-136439. It is.

  The sample dispersion liquid is passed through a flow path (spread along the flow direction) of a flat and flat transparent flow cell (thickness: about 200 μm). The strobe and the CCD camera are mounted on the flow cell so as to be positioned on opposite sides of the flow cell so as to form an optical path that intersects with the thickness of the flow cell. While the sample dispersion is flowing, strobe light is applied at 1/30 second intervals to obtain an image of the particles flowing through the flow cell, so that each particle has a certain range parallel to the flow cell. Photographed as a two-dimensional image. The diameter of a circle having the same area is calculated as the equivalent circle diameter from the area of the two-dimensional image of each particle. The circularity of each particle is calculated from the projected area of the two-dimensional image of each particle and the perimeter of the projected image using the above-described circularity calculation formula.

<Paper powder compatible configuration>
Next, a configuration corresponding to paper dust, which is a feature of the first embodiment, will be described with reference to FIGS.
FIG. 3 is a diagram illustrating the movement of the toner in the developing device according to the first embodiment. In the developing device 3 according to the first embodiment, the developing chamber 301 and the toner storage chamber 300 are connected through the opening Q. Then, the toner in the toner storage chamber 300 is transported to the developing chamber 301 through the opening Q by the toner transport member 34.

  As shown in FIG. 1, in the developing device 3, the bottom h of the developing chamber 301 is located above the bottom g of the toner storage chamber 300 in the vertical direction, and the regulating portion e is It is characterized by being located directly above. FIG. 1 shows the developing device 3 attached to the image forming apparatus. In FIG. 1, the vertical direction is the vertical direction, and the direction perpendicular to the vertical direction is the horizontal direction. The direction from the upper side to the lower side in the vertical direction is the direction of gravity.

  As shown in FIG. 1, when viewed in the direction of the rotation axis of the photosensitive drum 1, a straight line lowered in the direction of gravity from the regulating portion e is defined as a straight line B. When viewed in the rotation axis direction of the photosensitive drum 1, a straight line connecting the upper end portion X of the opening and the lower end portion Y of the opening is defined as a straight line A. In this embodiment, when viewed in the rotation axis direction of the photosensitive drum 1, the intersection f of the straight line A and the straight line B exists above a horizontal plane passing through the lower end Y of the opening. In the present embodiment, the rotation direction of the developing sleeve 31 is a direction from the lower end Y to the upper end X of the opening at a portion facing the opening Q.

  Further, the bottom h of the developing chamber 301 is located vertically above the bottom g of the toner storage chamber 300. As shown in FIG. 1, the bottom h is the lowest part in the developing chamber 301 in a state where the developing device 3 is mounted on the image forming apparatus main body, and the bottom g is the same as the bottom of the developing device 3 Is the lowermost part of the toner storage chamber 300 in a state where the toner storage chamber is mounted.

  Further, in this embodiment, the axial center i of the toner conveying member 34 in the toner storage chamber 300 is disposed below the axial center j of the developing sleeve 31 in the vertical direction. Therefore, the developing device is of a toner scooping type in which the toner is scooped up from the toner accommodating chamber 300 and supplied to the developing chamber 301.

  With such a configuration, the toner in the developing device 3 moves as indicated by arrows C1 to C3 in FIGS. 3A and 3B. FIG. 3A shows a state (toner C <b> 1) in which the toner has been sent from the toner storage chamber 300 to the developing chamber 301 by the toner conveying member 34. The toner in the developing chamber 301 moves as indicated by an arrow C2 as the developing sleeve 31 rotates.

  The toner supplied to the developing sleeve 31 by the magnetic force is conveyed by the rotation of the developing sleeve 31. The toner conveyed to the regulating portion e of the developing sleeve 31 is stripped off by a regulating blade 33. Such surplus toner creates a flow (arrow C2) that returns to the toner storage chamber in such a way as to be pushed out by toner coming later. In particular, as shown in FIG. 3B, after the tip of the toner conveying member 34 has passed through the opening Q, the toner around the regulating blade 33 falls freely in the direction of gravity (vertically) and returns to the toner storage chamber 300. It will be easier.

  Next, the movement of the paper dust in the first embodiment will be described in detail with reference to FIG. FIG. 4 is a diagram illustrating the movement of the paper dust in the first embodiment. Dashed arrows D1 to D4 in FIG. 4 indicate the movement of the paper dust.

  The paper powder attached to the photosensitive drum 1 from the paper P at the transfer portion b becomes negative polarity by receiving a negative discharge when passing through the charging nip. The negatively charged paper dust is electrically collected in the developing sleeve 31 in the developing section a (arrows D1 → D2).

The paper powder collected in the developing sleeve 31 is mixed with the magnetic toner present in the developing chamber 301 and is conveyed to the regulating section e. The magnetic toner is attracted to the developing sleeve 31 by the magnetic force, but the paper powder has no magnetic force, so that the force of adhering to the developing sleeve 31 is small. Therefore, even if the toner is transported to the regulating portion e, the regulating blade 33 peels off the toner along with the excess toner from the developing sleeve 31.

  The paper dust separated from the developing sleeve 31 by the regulating unit e is conveyed from the developing chamber 301 to the toner storage chamber 300 located at a lower position by the toner circulating force and gravity (arrow D3). The paper dust sent to the toner storage chamber 300 may be transported again to the developing chamber 301 by the toner transport member 34 or the like. However, since the toner is of a pumping type, the paper dust having no magnetic force is subjected to gravity. , And is not supplied to the developing sleeve 31 like magnetic toner.

  As shown in FIG. 4, in the first embodiment, since the opening Q that connects the developing chamber 301 and the toner storage chamber 300 is disposed immediately below the regulating unit e, the paper powder that has been efficiently separated by the regulating unit e is removed by the toner. It can be sent into the accommodation room 300. Therefore, since paper dust does not continue to exist near the developing sleeve 31, it is possible to reduce a risk that the paper dust is caught between the developing sleeve 31 and the regulating blade 33 or passes through the regulating portion e.

  Note that the opening Q in the present embodiment is a space between the upper end X and the lower end Y of the first frame 3A constituting the developing chamber 301. In this embodiment, the space between the upper end portion X of the opening and the lower end portion Y of the opening (that is, the opening Q) may be just below the regulating portion e. Here, as shown in FIG. 4, there may be a configuration in which a part (projection Z in FIG. 4) of the second frame 3B constituting the toner storage chamber 300 projects to cover the opening Q. In the case of such a configuration, the space between the protruding portion Z of the second frame 3B and the upper end X of the opening of the first frame 3A may be just below the regulating portion e. That is, when the opening Q is covered with the second frame 3B, the dotted line m in FIG. 4 is located between the dotted line 1 and the dotted line n, and the regulating portion e is located above the projecting portion Z in the vertical direction. I just need. On the other hand, when the opening Q is not covered with the second frame 3B, the dotted line m in FIG. 4 is located between the dotted line k and the dotted line n, and the restricting portion e is in the vertical direction of the lower end Y of the opening. It only has to be above. The dotted lines k, l, m, and n are vertical straight lines passing through the lower end portion Y of the opening, the protruding portion Z, the regulating portion e, and the upper end portion X of the opening, respectively.

  FIG. 12 shows a conventional developing device. In the conventional developing device, the restricting portion e is not located immediately above (upper) the opening Q connecting the developing chamber 301 and the toner storage chamber 300 in the vertical direction. Further, the bottom h of the developing chamber 301 is located below the bottom g of the toner storage chamber 300 in the vertical direction.

  Therefore, paper dust at a position distant from the developing sleeve 31 continues to exist in the developing chamber 301. Therefore, there is a risk that paper dust is supplied to the developing sleeve 31. The paper powder near the developing sleeve 31 is pressed against the developing sleeve 31 by the pressure of the toner supplied from the toner storage chamber 300. Such paper dust may adhere to the developing sleeve 31 and reach the regulating portion e, and may be caught between the developing sleeve 31 and the regulating blade 33 or may pass through the regulating portion e.

  On the other hand, as described above, in the first embodiment, by using a toner having a low cohesion degree and a high sphericity as the toner, the effect of the configuration corresponding to the paper powder in the developing device shape as in the present embodiment is obtained. Easy to demonstrate. Since toner having a high degree of cohesion is easily loosened, paper powder and toner are easily separated. The toner having a high sphericity also has a small number of contact points with the paper powder, and the adhesive force with the toner is reduced. Therefore, the paper powder and the toner are easily separated. Further, the toner having a low cohesion degree has a high fluidity, and the circulation between the developing chamber and the toner storage chamber 300 becomes active, so that the paper dust can be easily transported to the toner storage chamber 300. As described above, by using a toner having a low degree of agglomeration and a high degree of sphericity, the effect of the configuration corresponding to the paper dust of Example 1 is easily exerted.

  Further, with reference to FIG. 5, a contact state and a contact pressure of the regulating blade 33 with the developing sleeve 31 in the first embodiment will be described. FIG. 5A is a schematic diagram illustrating a contact state between the regulating blade and the developing sleeve according to the first embodiment and a distribution of a contact pressure. FIG. 5B is a schematic diagram illustrating the regulating blade and the developing sleeve according to the first modification. FIG. 4 is a schematic diagram showing a contact state and a distribution of a contact pressure with the contact.

  In the first embodiment, as shown in FIG. 5A, the edge 33 a 1 of the tip 33 a of the regulating blade 33 is in contact with the surface of the developing sleeve 31. On the other hand, in the first modification, as shown in FIG. 5B, the abdomen 33 a 1 of the tip 33 a of the regulating blade 33 is in contact with the surface of the developing sleeve 31.

  Here, an arrow E1 in FIGS. 5A and 5B indicates the movement of the paper dust. In the configuration of the first embodiment, the contact pressure applied to the tip side of the regulating blade 33 increases, and even if the paper dust reaches the vicinity of the regulating portion e, it is peeled off at the entrance of the regulating portion e. On the other hand, in the configuration of the first modification, the contact pressure of the regulating blade 33 is broad, so that the contact pressure at the entrance of the regulating portion e is weak, and paper dust enters between the regulating blade 33 and the developing sleeve 31. there is a possibility.

  As described above, by increasing the peak of the contact pressure in the vicinity of the edge 33a1 of the distal end portion 33a of the regulating blade 33, it is possible to further suppress the toner from slipping or being caught between the regulating blade 33 and the developing sleeve 31. Can be.

(Example 2)
Next, a second embodiment will be described with reference to FIG. FIG. 6A is a schematic diagram illustrating a contact state and a contact pressure distribution between the regulating blade and the developing sleeve according to the second embodiment, and FIG. 6B is a diagram illustrating a regulation according to a second modification of the second embodiment. FIG. 3 is a schematic diagram illustrating a contact state between a blade and a developing sleeve and a distribution of a contact pressure. The configurations of the developing devices according to the second embodiment and the second modification are the same except that the configuration of the regulating blade is different. Therefore, the same components are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 6A, the regulating blade 33 according to the second embodiment has a step 331 upstream of the developing sleeve 31 in the rotation direction of the developing sleeve 31 so as to have a gap between the distal end 33a and the developing sleeve 31. are doing. That is, the regulating blade 33 according to the second embodiment has a shape having the eaves 332.

  By providing the eaves 332, large paper dust is removed from the developing sleeve by the eaves portion 332 before reaching the regulating portion e (arrow E1 in FIG. 6). Since the gap between the eaves portion 332 and the developing sleeve 31 is narrow, the gap between the eaves portion 332 and the developing sleeve 31 is compacted by the toner that has been conveyed. Accordingly, even small paper dust is prevented from entering by the toner in the compacted state accumulated in the eaves portion 332, so that the paper dust hardly enters the regulating portion e.

  In the second embodiment, as shown in FIG. 6A, the edge 331 a of the step portion 331 of the regulating blade 33 is in contact with the surface of the developing sleeve 31. Therefore, the peak pressure in the regulating portion e can be set high, and it is possible to suppress the toner from slipping or being caught between the developing sleeve 31 and the regulating blade 33.

  In the second embodiment, the height H of the step portion 331 is set to 300 μm, and the length 1 of the eave portion is set to 1.0 mm. However, the present invention is not limited to this. It is preferable to set the eaves length to 0.5 to 2.5 mm.

  The same effect can be obtained with the shape of the second modification of the second embodiment shown in FIG. Also in this shape, the height H of the step is set to 300 μm, the eaves length 1 is set to 1.0 mm, and the R of the projection 334 is set to 0.4 mm.

  As described above, by using the regulating blade 33 having the shape of the second embodiment and the modification of the second embodiment, it is possible to remove large paper dust in advance before reaching the regulating portion e. Further, it is possible to suppress the occurrence of an image defect due to paper dust being caught or slipped between the developing sleeve 31 and the regulating blade 33.

(Example 3)
The details according to the third embodiment will be described below.

<Outline of Overall Configuration of Image Forming Apparatus>
First, with reference to FIG. 7, an outline of the entire configuration of the image forming apparatus according to the present embodiment will be described. FIG. 7 is a schematic sectional view illustrating the entire configuration of the image forming apparatus according to the present embodiment. In this embodiment, a monochrome laser printer using a transfer type electrophotographic process is used as the image forming apparatus. Note that items that are not particularly described here are the same as those in the first and second embodiments. In the third embodiment, configurations common to the first and second embodiments are denoted by the same reference numerals as in the first and second embodiments, and description thereof is omitted.

The photosensitive drum 1 of the present embodiment is a negative OPC photosensitive member having a diameter of 20 mm. The photosensitive drum 1 is provided so as to be rotatable at a peripheral speed (process speed, printing speed) of 150 mm / sec in the direction of arrow R1 in the drawing. Compared with the image forming apparatus of the first embodiment, the diameter of the photosensitive drum is made smaller to make it smaller. Further, the position of the light removing means 8 is located just above the top of the photosensitive drum, and is different from the structure of the first embodiment in that it is located on the contact charging member side.
<Compatible with charging roller contamination>
In this embodiment, the following two configurations are employed in order to allow the transfer residual toner to pass through the charging nip without adhering to the charging roller 2.

  First, as shown in FIG. 8, a light removing member 8 is provided between the transfer roller 5 and the charging roller 2 in the rotation direction of the photosensitive drum. The light neutralizing member 8 optically neutralizes the surface potential of the photosensitive drum 1 after passing through the transfer nip in order to perform stable discharge at the charging nip. By setting the potential of the photosensitive drum 1 before charging to about -150 V in the entire longitudinal direction by the light removing member 8, uniform discharge can be performed at the time of charging, and the transfer residual toner can be made to have a uniform negative polarity. . As a result, the transfer residual toner passes through the charging nip.

  Second, the charging roller 2 is driven and rotated with a predetermined peripheral speed difference from the photosensitive drum 1. As described above, most of the toner has a negative polarity due to the discharge, but some toner that has not been completely converted to the negative polarity remains, and this toner may adhere to the charging roller 2 at the charging nip. Therefore, by rotating the charging roller 2 and the photosensitive drum 1 while providing a predetermined peripheral speed difference, it is possible to make such toner negative by sliding friction between the photosensitive drum 1 and the charging roller 2. Become. This has the effect of suppressing toner from adhering to the charging roller 2.

Description will be given of a configuration of an optical dividing conductive means and the charging roller according to the configuration for reducing the toner adhesion to the charging roller.

<Light dividing conductive member>
As shown in FIG. 9, the light dividing conductive member 8 irradiates LED81, which are arranged in the image forming apparatus main body light from the photosensitive drum longitudinal ends, arranged the irradiated light so as to face the photosensitive drum 1 a longitudinal Light is irradiated to the entire length of the photosensitive drum 1 through the light pipe 82 thus formed. With this configuration, it is possible to suppress variations in the amount of light irradiated over the length of the photosensitive drum 1. As another optical dividing conducting means 8 may be a LED array longitudinally LED it is arranging a plurality of photosensitive drums.

<Charging roller (contact charging member)>
The charging roller 2 has a core metal 2a of Φ6, a conductive elastic layer 2b covering the core metal 2a, and a surface layer covering the surface of the elastic elastic layer. The outer diameter of the portion having the conductive elastic layer and the surface layer is about Φ10. The charging roller 2 is pressed against the photosensitive drum by a spring with a pressure of about 400 g on one side. Thereby, the charging roller 2 and the photosensitive drum 1 form a predetermined nip. In this embodiment, a charging roller gear is provided on the core metal 2a of the charging roller 2, and the charging roller gear is engaged with a drum gear provided at an end of the photosensitive drum. Therefore, as the photosensitive drum 1 rotates, the charging roller 2 also rotates. At the contact portion (contact portion) between the surface of the charging roller 2 and the surface of the photosensitive drum 1, the respective surfaces move in the same direction (forward drive). The peripheral speed (moving speed of the surface) of the surface of the charging roller 2 is set to be 15% faster than the peripheral speed of the surface of the photosensitive drum 1.

<Positional relationship between the charging roller and the light dividing conductive member>
Recently, the downsizing of the image forming apparatus has been diameter of the photosensitive drum 1, the distance of the charging roller 2 and the light dividing collecting member 8 becomes closer. Therefore, toner and paper particles that entered the charging nip, is then scattered by the driving of the charging roller 2 which may happen to soil the light dividing conductive member 8. Particularly, the light pipe 82 may be stained.

In this embodiment, the order corresponding to the above-mentioned problems, an optical dividing conducting means 8 than the charged portion c to form a charging nip is disposed upward in the gravity direction. That is, the position of the charging portion c, which is the contact portion on the photosensitive drum side of the portion where the charging roller contacts the photosensitive drum (the portion of the photosensitive drum that contacts the charging roller), is positioned vertically below the light removing means 8. Take configuration. As a result, the toner and paper dust scattered by the driving of the charging roller 2 basically fall in the direction of gravity. Thus, by arranging the light dividing conductive member above the charging portion c, can be reduced to a toner and paper dust that has fallen scattered is dirty light dividing conductive member 8.

Further, as described above, the driving direction of the charging roller 2 is forward with respect to the surface of the photosensitive drum 1 and the peripheral speed of the charging roller 2 is faster than that of the photosensitive drum 1. With this configuration, the toner and paper dust on the photosensitive drum are pushed out by the charging roller to the downstream side in the rotation direction of the photosensitive drum (or the downstream side in the rotation direction of the charging roller). Therefore, in the charging nip, it is unlikely that the toner or the paper powder is scraped off. Further, even if the charging roller has happened that scraping toner and paper dust on a photosensitive drum, a direction to the scattering of the toner or paper dust, the light dividing conductive means is a rotational direction downstream side are arranged Is a direction toward the opposite side (the upstream side in the rotation direction). Therefore, it is reduced to scatter over the light dividing conductive means.

(Example 4)
The arrangement of the charging roller and the light dividing conductive member is a feature of this embodiment, shown in FIG. 10. The configuration other than these arrangements is the same as in the above embodiment, and the description is omitted.

In this embodiment, as shown in FIG. 10, the charging roller 2 and the light dividing conductor means 8, they are arranged respectively on opposite sides of the vertex u and the center v straight line connecting the photosensitive drum 1. Thus, as shown in FIGS. 7 and 8, than when light discharging device is located at the apex of the photosensitive drum 1, the toner or paper dust scattered by the charging nip is reduced from adhering to the light dividing conductive means I have. Since the vertex u of the photosensitive drum 1 between the charging roller 2 and the light dividing conducting means 8 is present, toner and paper dust scattering has become difficult to reach construction to the light dividing photoelectric means side. As described above, since the scattered toner and paper powder basically fall immediately, only a very small amount of the toner or paper powder exceeds the top of the photosensitive drum. Therefore, it does not pollute the light dividing conducting means enough to significantly reduce the amount of light.

The movement of the transfer residual toner and the paper dust will be described with reference to FIG. 11A shows Example 3, FIG. 11B shows Example 4, and FIG. 11C shows a comparative example. Comparative Examples are light removal conducting means 8 provided below the charging roller 2, a further movement direction of the charging roller 2 surface is driven to the photosensitive drum 1 surface and the reverse configuration.

Arrow A in the figure indicates the movement of the transfer residual toner and the paper dust. 11A and 11B, since the charging roller 2 is driven in the forward direction, most of the toner and paper powder pass through the charging nip. Somewhat, it is the toner and paper powder scatters in the charging nip, they again lands on the photosensitive drum 1 without reaching the light dividing conductor means. In contrast, in the configuration of the comparative example of FIG. 11c, the toner and paper dust scraped by the charging nip to fall downwards, adhering to the light dividing conductor means 8. Therefore, the light dividing conductive means 8 there is a possibility that it becomes impossible illuminated by dirt, removal lightning in sufficient quantity.

As explained above, the arrangement of the charging roller 2 and the light dividing conductive member 8 as shown in Examples 3 and 4, a configuration, the light dividing conducting means 8 is reduced to soiling by paper dust and toner Is now possible. With this configuration, the charging roller 2 and the light dividing conducting means can the be the image forming apparatus the distance to nearby 8, also becomes possible to contribute to miniaturization of the cartridge used therein.

In the third and fourth embodiments, the monochrome image forming apparatus adopts the contact development using the magnetic toner. However, the present invention is not limited to this, and the full-color image adopting the contact development method using the non-magnetic toner and the toner supply roller is used. It may be a forming device. Further, in the image forming apparatus according to this embodiment, the photosensitive drum 1, charging roller 2, developing device 3, when the process cartridge with an integrated structure including a light dividing conductive means 8 and detachably attached to the apparatus main body However, the configuration of the cartridge is not limited to this. For example, except for the photosensitive drum 1 and the developing device 3, the charging roller 2 may be detachably attached to the apparatus body and a cartridge with an integrated structure including a light dividing conductor means 8.

Reference numeral 2: charging roller (contact charging member), 3: developing device, 31: developing sleeve (developer carrier), 33: regulating blade (regulating member), 34: toner conveying member (conveying member), 300: toner storage chamber , 301 ... developing chamber, 8 ... light dividing conducting means, 81 ... LED, 82 ... light pipe

Claims (12)

An image carrier;
A transfer unit that transfers the developer image formed on the image bearing member onto a transfer material,
A developer is supplied to the image carrier on which a contact charging member for charging the surface of the image carrier is disposed, and after a developer image formed on the image carrier is transferred to a transfer-receiving material, Having a developing device for collecting the developer remaining on the image carrier,
The developing device includes:
A developer carrier that carries the developer on the surface,
A regulating member that regulates the layer thickness of the developer that is in contact with the developer carrier and that is carried on the surface of the developer carrier,
A developing chamber frame forming a developing chamber having an opening provided with the developer carrier and the regulating member;
A storage chamber frame that forms a storage chamber that stores the developer,
A transfer member provided in the storage chamber and configured to transfer the developer stored in the storage chamber through the opening to the development chamber,
The contact charging member is disposed downstream of the light removing unit in the rotation direction of the image carrier, and a peripheral speed difference is generated between the surface of the contact charging member and the surface of the image carrier. Driven,
The contact portion of the image carrier with the contact charging member is located vertically below the light removing unit,
The bottom of the developing chamber is located vertically above the bottom of the storage chamber,
The developing contact portion of the developer carrier that the restricting member contacts is located immediately above the opening in the vertical direction,
The regulating member has a convex portion that comes into contact with the developer carrier, and a tip portion that protrudes upstream of the convex portion in the rotation direction of the developer carrier, and has a surface that faces the developer carrier. A gap is formed between the developer carrier and the tip by the protrusion and the tip, and the gap between the developer carrier and the tip is opposite to the surface of the developer carrier facing the surface of the developer carrier in the gap. The image forming apparatus according to claim 1, wherein a height of the protrusions in the direction toward the surface is 200 to 400 m. An image carrier;
A transfer unit that transfers the developer image formed on the image bearing member onto a transfer material,
A developer is supplied to the image carrier on which a contact charging member for charging the surface of the image carrier is disposed, and after a developer image formed on the image carrier is transferred to a transfer-receiving material, Having a developing device for collecting the developer remaining on the image carrier,
The developing device includes:
A developer carrier that carries the developer on the surface,
A regulating member that regulates the layer thickness of the developer that is in contact with the developer carrier and that is carried on the surface of the developer carrier,
A developing chamber frame forming a developing chamber having an opening provided with the developer carrier and the regulating member;
A storage chamber frame that forms a storage chamber that stores the developer,
A transfer member provided in the storage chamber and configured to transfer the developer stored in the storage chamber through the opening to the development chamber,
The contact charging member is disposed downstream of the light removing unit in the rotation direction of the image carrier, and a peripheral speed difference is generated between the surface of the contact charging member and the surface of the image carrier. Driven, and the contact portion of the image carrier with the contact charging member is, with respect to a straight line connecting the vertex of the image carrier and the rotation center when viewed in the rotation axis direction of the image carrier. , Is located on the opposite side to the light neutralization means,
The bottom of the developing chamber is located vertically above the bottom of the storage chamber,
The developing contact portion of the developer carrier that the restricting member contacts is located immediately above the opening in the vertical direction,
The regulating member has a convex portion that comes into contact with the developer carrier, and a tip portion that protrudes upstream of the convex portion in the rotation direction of the developer carrier, and has a surface that faces the developer carrier. A gap is formed between the developer carrier and the tip by the protrusion and the tip, and the gap between the developer carrier and the tip is opposite to the surface of the developer carrier facing the surface of the developer carrier in the gap. The image forming apparatus according to claim 1, wherein a height of the protrusions in the direction toward the surface is 200 to 400 m. The developer is a magnetic developer,
The developer carrier includes an included magnetic field generating unit,
The image forming apparatus according to claim 1, wherein the transport member moves the magnetic developer stored in the storage chamber upward and supplies the magnetic developer to the developer carrier through the opening. .   The developer remaining on the image carrier after the developer image formed on the image carrier is transferred to the transfer material is transferred to the transfer material in the rotation direction of the image carrier. 4. The image forming apparatus according to claim 1, wherein the toner image is collected by the developing device without being collected from the surface of the image carrier downstream of the transfer unit and upstream of the developing device. 5. Image forming apparatus.   5. The image according to claim 1, wherein the contact charging member is driven such that a portion contacting the contact portion moves in the same direction as the contact portion. 6. Forming equipment.   The image forming apparatus according to claim 1, wherein a peripheral speed of a surface of the contact charging member is higher than a peripheral speed of a surface of the image carrier. 7. The image forming apparatus according to claim 1, wherein an axis of the rotatable developer carrier is vertically higher than an axis of the rotatable conveying member.
Item 10. The image forming apparatus according to item 1.   The image forming apparatus according to claim 1, wherein the developing contact portion is positioned vertically above an axial center of the transport member rotatably provided.   9. The image forming apparatus according to claim 1, wherein a rotation direction of the developer carrier is a direction from a lower end to an upper end of the opening at a portion facing the opening. 10. apparatus.   The image forming apparatus according to claim 1, wherein an average circularity of the developer is 0.93 or more.   The image forming apparatus according to claim 1, wherein a cohesion degree of the developer is 55 or less.   The image forming apparatus according to any one of claims 1 to 11, wherein the light neutralizing unit optically neutralizes a surface potential of the image carrier.

Images