JPH11305540A - Image forming device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device and method which can secure the pressure of contact between a developer carrier and a developer regulation means and reduce the pressures of the developer regulation means and an image carrier. SOLUTION: In an image forming device having an image carrier on which an electrostatic latent image is formed and a developer carrier which carries a one-component developer, the developer carrier comprises a flexible and magnetic cylindrical thin film member 17, a shaft member 15, and thin film holding members 16 mounted near both ends of the shaft member 15 to hold the cylindrical thin film member 17, and has an approximately cylindrical space inside the cylindrical thin film member 17, the space being surrounded by the cylindrical thin film member 17, the thin film holding members 16, and the shaft member 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus and an image forming method using an electrophotographic method used for, for example, a copying machine, a printer, a facsimile, etc. It relates to a developing roller.

[0002]

2. Description of the Related Art An image forming apparatus using an electrophotographic method is:
The configuration differs slightly depending on the type of developer (hereinafter referred to as toner) used. However, when a one-component developer (hereinafter, referred to as a one-component toner) is used, there is only a difference between a magnetic one-component toner and a non-magnetic one-component toner as to whether or not a magnet is required in a developing roller. Have almost the same configuration.

Conventionally, as an image forming apparatus using a non-magnetic one-component toner, a non-magnetic one-component toner is supplied to a surface of an elastic roller as a developer carrier, and a developing blade as a developer regulating means is provided on the elastic roller. Japanese Patent Application Laid-Open No. 52-143831 discloses a method in which a charged toner thin layer is formed on the outer peripheral surface of a roller by pressure contact, and the charged toner thin layer is brought into direct contact with the surface of a photosensitive drum as an image carrier to form a toner image. It is proposed in a gazette (hereinafter referred to as a first conventional example). In such a non-magnetic one-component image forming apparatus, the developing roller is rotated at a speed higher than the peripheral speed of the photosensitive drum in order to obtain a desired image density.

In the image forming apparatus according to the first conventional example, in order to form a charged toner thin layer on the surface of the developing roller, the developing blade needs to contact the developing roller with a certain level of pressure contact force. Therefore, the altitude required for the elastic developing roller is relatively high, and conversely, the elastic developing roller is used to prevent damage to the photosensitive drum and disturbance due to rubbing of the developed toner image at the contact portion with the photosensitive drum. The required hardness of the roller is very low.

[0005] However, there is no developing roller having such completely contradictory properties, and there is a problem that one of the requirements must be sacrificed.

Further, in response to recent demands for energy saving, attempts have been made to reduce the amount of heat consumed by the fixing device by using toner having a low melting point. However, when a toner having a low melting point is used in the developing device as described above, the toner melts due to frictional heat generated by the rubbing between the developing roller and the photosensitive drum, and the toner sticks to the photosensitive drum and the developing roller. Failure occurs.

On the other hand, Japanese Patent Laid-Open No. 63-226676 discloses a configuration in which the above-mentioned problem is solved and the contact pressure at the rubbing portion between the developing roller and the photosensitive drum is low and the developing blade contact portion can be pressurized to some extent. (Hereinafter referred to as a second conventional example).

In the second conventional example, a thin film on a cylinder having a circumference longer than the circumference of the developing roller driven by rotation is provided on the developing roller, and guide members provided at both ends of the developing roller are provided. A space is created between the developing roller and the thin film member at the opposite portion between the developing roller and the photosensitive drum, and development is performed by bringing the outer surface of the thin film member into contact with the outer peripheral surface of the photosensitive drum.

In this way, a certain contact pressure is ensured at the contact portion between the developing blade and the thin film member so as to sufficiently charge the toner, and the contact portion between the photosensitive drum and the thin film member is formed between the thin film member and the developing roller. The space is configured to reduce the contact pressure.

[0010]

In the above-mentioned second conventional example, a space is created between the developing roller and the thin film member at a portion where the developing roller and the photosensitive drum are opposed to each other. The contact pressure at the contact portion between the roller and the photosensitive drum is dispersed. Further, at the developing blade contact portion, since the developing roller exists on the back side of the thin film member, it is possible to apply a certain amount of pressure by the developing blade.

However, in this configuration, although the pressure can be reduced at the contact portion between the developing roller and the photosensitive drum, the developing roller and the thin film member are not fixedly bonded. Therefore, since the driving of the thin film member relies on the frictional force between the front surface of the developing roller and the back surface of the thin film member, the following problems occur.

A frictional force acts on the thin-film member with a developing blade for forming at least a thin layer of toner, a guide member for lifting the thin-film member from the surface of the developing roller and pressing the thin-film member against the photosensitive drum. Since these frictional forces act in the opposite direction to the frictional force between the surface of the developing roller and the back surface of the thin film member, a large force is applied between the surface of the developing roller and the back surface of the thin film member. If this is used for a long period of time, there is a possibility that the thin film member wears on the surface of the developing roller, causing a slip, making it impossible to supply toner to the photosensitive drum and making image formation impossible.

When a non-magnetic toner is used, the adhesion of the toner is mainly a Coulomb force due to the electric charge of the toner. For this reason, a means for applying a charge to the toner before being carried on the developing roller is required. In the configuration in which the thin film member is not provided and the toner is carried on the surface of the developing roller, a toner supply roller or the like that comes into contact with the surface of the developing roller and rotates in the reverse direction is provided, and the toner is frictionally charged by the contact rotating portion. The toner is carried on the developing roller.

However, the frictional force between the developing blade and the photosensitive drum already acts on the outer periphery of the thin film member in the second conventional example as described above, and in addition to this, a toner supply roller is provided. It is difficult to obtain a stable driving force. Therefore, in the second conventional example, there is a problem that the amount of toner carried on the thin film member becomes unstable due to insufficient charge application of the toner, and the image density becomes non-uniform.

The toner supply roller also serves to supply toner to the developing roller and to remove toner that has not contributed to development (hereinafter referred to as undeveloped toner) from the developing roller. However, in the second conventional example, the toner supply roller cannot be brought into pressure contact with a sufficient pressure, so that the undeveloped toner cannot be satisfactorily removed from the thin film member and partially remains. For this reason, the difference between the amount of toner in the portion where the undeveloped toner has adhered and the amount of toner in the portion where the undeveloped toner has adhered causes a so-called ghost, in which the history of the previous image appears in the next image. It is difficult to get.

Further, since the developing roller and the thin film member are separated from each other, a "deviation" occurs in which the thin film member is shifted to one of the left and right ends due to the rotation of the developing roller, and the end of the thin film member is moved to the developing device. The end part may be damaged by colliding with a wall or the like. Further, if a member for avoiding collision is provided at the end of the thin film member in order to avoid this, the production cost of the developing device increases.

In view of the above problems, the present invention provides a high-quality image while ensuring the contact pressure between the developer carrying member and the developer regulating means, and reducing the pressure between the developer regulating means and the image carrying member. To provide an image forming apparatus and an image forming method capable of stably obtaining the image.

[0018]

In order to solve the above-mentioned problems, a typical configuration of an image forming apparatus according to the present invention comprises an image carrier on which an electrostatic latent image is formed, and a one-component developer. A developer-carrying member for carrying the developer; and a developer regulating means having at least a magnetic pole for regulating the amount of the one-component developer on the surface of the developer carrier and for giving a charge to the one-component developer. Forming an image by contacting the developer carrier with the image carrier, developing the electrostatic latent image on the image carrier with the one-component developer, and transferring the developed image onto a recording medium; In the apparatus, the developer carrier includes a cylindrical thin film member having flexibility and magnetism, a shaft member, and a thin film holding member attached near both ends of the shaft member to hold the cylindrical thin film member. Inside the cylindrical thin film member, the cylindrical thin film member, Holding member, and characterized in that it has a substantially cylindrical space surrounded by said shaft member.

A typical configuration of an image forming method according to the present invention for solving the above-mentioned problems is a flexible cylindrical thin film member and a thin film holding member inside both ends of the cylindrical thin film member. The one-component developer is carried while the developer carrier having a space therein is rotated by being integrated with the shaft member, and the developer regulating means and the surface of the developer carrier are moved by the developer regulating means. After applying a charge to the one-component developer at least while being attracted by a magnetic force, developing is performed by bringing the surface of the cylindrical thin film member of the developer carrier into contact with the image carrier on which an electrostatic latent image is formed. It is characterized by.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] Next, an image forming apparatus according to the present invention will be described with reference to the drawings, and an image forming method will also be described. FIG. 1 is a perspective view showing a developer carrier according to the embodiment, FIG. 2 is an overall configuration diagram of an image forming apparatus according to the embodiment, FIG. 3 is an exploded configuration diagram of the developer carrier, and FIG. FIG. 5 is a diagram illustrating a member width of the carrier, the image carrier, and the developer regulating unit. FIG. 5 is a diagram illustrating a contact state between the developer carrier and the image carrier. FIG. 6 is a diagram illustrating the developer carrier and the developer regulating unit. It is a figure explaining the contact state of.

First, the overall configuration of the image forming apparatus according to the present embodiment will be described with reference to FIG. The image forming apparatus shown in the figure employs an electrophotographic system. The photosensitive drum 1, which is a rotatable image carrier, is electrically grounded, and rotates at a rotation speed Vx in the direction of arrow X. The photosensitive drum 1 is uniformly charged by a primary charger 2, and is exposed to an information signal by a light emitting element 3 such as a laser to form an electrostatic latent image.

The electrostatic latent image formed on the photosensitive drum 1 is
A toner image is formed by developing with a developing device 4 described later. The developing device 4 contains a non-magnetic one-component toner T, and a developing roller 9 as a developer carrier is brought into contact with the photosensitive drum 1. The developing roller 9 is applied with a negative DC voltage 14 and rotates at a rotation speed Vy in the direction of arrow Y. Here, the rotation speed Vy of the developing roller 9 is higher than the rotation speed Vx of the photosensitive drum 1. Further, the developing device 4 includes a developing blade 10 as a developer regulating means, a supply roller 11 rotating in the direction of arrow Z, a blowout prevention sheet 13, and a stirring member 12 for stirring the non-magnetic one-component toner T.

The formed toner image is transferred to a transfer material 8 by a transfer roller 5, and then an image is formed by applying heat and pressure by a fixing device 7. The transfer residual toner on the photosensitive drum 1 is removed by the cleaning device 6.

Next, each component of the developing device 4 will be described.

(Developing Roller) First, the possible configuration of the developing roller 9 will be described with reference to FIG. As shown in the figure, the developing roller 9 includes a shaft member 15, a cylindrical thin film member 17 made of a flexible and magnetic material, and an elastic thin film holding member 16 disposed at both ends of the cylindrical thin film member 17. It is composed of

Here, the thin film holding member 16 is bonded to the shaft member 15 and the cylindrical thin film member 17, and the cylindrical thin film member 17 is
It rotates integrally with the rotation of 15. Furthermore, cylindrical thin film members
Since both ends of 17 are held by the thin film holding member 16, the cylindrical thin film member 17 is not in contact with the shaft member 15, and the cylindrical thin film member 17 and the thin film holding member 1 are provided inside the cylindrical thin film member 17.
6, a substantially cylindrical space surrounded by the shaft member 15 is formed.

As the shaft member 15, a rigid body such as stainless steel or aluminum can be used. The shape may be a cylindrical shaft, and the diameter of the central portion may be made larger than the diameter of both ends, for example, also for positioning the thin film holding member 16.

The cylindrical thin film member 17 is made of a metal thin film such as an iron thin film or a nickel electroformed thin film, an alloy metal thin film of a magnetic material such as nickel or cobalt and the above metal, or a polycarbonate, polyethylene terephthalate, polyamide, or a fluorine-based resin. A sheet obtained by laminating a soft resin sheet made of the above resin and the metal thin film is used.

Further, since the above-mentioned sheet comes into direct contact with the toner T, it is preferable that the charge-imparting property to the toner is large. In the present invention, since a negatively chargeable toner is used, the surface of the cylindrical thin film member 17 may be coated with a silicone resin, a urethane resin, a polyamide resin, or the like, which has a negative charge to the toner. good.

The thickness of the cylindrical thin film member 17 is 30 to 100.
It is preferably about μm. If the thickness of the cylindrical thin film member 17 is 30 μm or less, the surface of the cylindrical thin film member 17 is wrinkled or twisted when rubbed against the photosensitive drum, and it is difficult to perform stable development. When the thickness of the metal thin film is 100 μm or more, the flexibility of the cylindrical thin film member 17 is lost, and the thin film member 17 operates as if it were a rigid member. As a result, the thin film is formed at the contact portion between the photosensitive drum 1 and the developing roller 9. Even if the holding member 16 is an elastic member of low hardness, it is difficult to make contact with light pressure.

The surface of the cylindrical thin film member 17 preferably has an appropriate roughness so that the toner T in the developing device 4 can be easily carried and transported. This surface roughness is a ten-point average roughness Rz
3-15 μm is preferred. When Rz is 3 μm or less, the toner transport amount is small, and it becomes difficult to obtain a predetermined image density,
If the thickness is 15 μm or more, density unevenness corresponding to the surface roughness of the cylindrical thin film member 17 occurs in the output image. The ten-point average roughness Rz used the definition shown in JIS B0601, and the surface roughness tester “SE-30H” manufactured by Kosaka Laboratory was used for the measurement.

The thin film holding member 16 is formed of a material having elasticity such as a rubber elastomer such as silicone rubber. In addition to silicone rubber, many elastomers such as urethane rubber, ethylene / propylene rubber (EPDM rubber), natural rubber, and styrene / butadiene rubber can be used.

The rubber hardness of these rubbers / elastomer is preferably 20 to 65 degrees (JIS A) as measured by a JIS A rubber hardness meter. When the rubber hardness is 65 degrees (JIS A) or more, the rubber elasticity decreases, so that the contact area of the contact portion between the photosensitive drum 1 and the cylindrical thin film member 17 decreases, and it becomes difficult to perform sufficient development. Further, when the rubber hardness is high, a slight change in the amount of intrusion when the developing roller 9 is pressed against the photosensitive drum 1 greatly changes the pressing force, which is not preferable in terms of configuration. On the other hand, when the rubber hardness is 20 degrees or less (JIS A) or less, the above-mentioned solid rubber is not preferable because the compression set becomes large and the rubber elasticity may be lost when left unattended.

The electrical resistance of the thin film holding member 16 is as follows.
In order to supply the developing bias from the shaft member 15 to the cylindrical thin film member 17 through the thin film holding member 16, it is preferable that the conductivity is high. However, for example, when a pinhole or the like is present on the surface of the photosensitive drum 1, an overcurrent may flow,
It is preferable that the thin film holding member 16 has some resistance. Specifically, the volume resistivity is preferably in the range of about 1e3 to 1e9 Ωcm.

The adhesive for bonding the cylindrical thin film member 17, the shaft member 15, and the thin film holding member 16 preferably has high conductivity in order to supply a developing bias from the shaft member 15 to the cylindrical thin film member 17.

The configuration that the developing roller 9 can take has been described above. The configuration of the developing roller 9 according to the present embodiment will be described with reference to FIG.

The shaft member 15 is formed of stainless steel.
The diameter of the central portion 15b is larger than that of the end portion 15a. Specifically, the end portion 15a is φ6 and the central portion 15b is φ8. Thereby, when the elastic thin film holding member 16 is press-fitted from both ends of the shaft member 15, the positioning thereof is performed by the end portion 15a and the central portion 15b.
And the positioning can be easily performed.

The thin film holding member 16 is made of EPDM rubber.
It is molded to an outer diameter of φ16. 20 parts by weight of conductive carbon black is added to the EPDM rubber, and the EPDM rubber is molded into a cylindrical shape by extrusion molding, subjected to primary vulcanization by a steam downstream method, further to secondary vulcanization, and then to about Ten
The thin film holding member 16 was obtained by cutting to a width of mm. The obtained thin film holding member 16 had a rubber hardness of 47 degrees (JIS A) and a volume resistance of 7e5 Ωcm.

As the cylindrical thin film member 17, a cylindrical nickel electroformed thin film having a relative magnetic permeability of about 3000 was used, and the surface was coated with a urethane resin of about 10 μm. Here, the urethane resin contains carbon particles to impart conductivity, and has an average surface resistance of 1e4 Ωcm. Nickel electroformed thin film thickness is 60μ
m, having a width in the longitudinal direction of 240 mm and an inner diameter of φ16.

Thereafter, the thin film holding member 16 was press-fitted into the shaft member 15 and the cylindrical thin film member 17 was bonded to form the developing roller 9. The developing roller 9 holds the cylindrical thin film member 17 with the thin film holding members 16 at both ends, and has a substantially cylindrical shape surrounded by the cylindrical thin film member, the thin film holding member, and the shaft member inside the cylindrical thin film member. A space is formed. As described above, the developing roller 9 according to the present invention has a small number of parts and is easy to manufacture.

(Toner Control Member) The developing blade 10 serving as a toner control member controls the layer thickness of the toner adhered to the outer peripheral surface of the photosensitive drum 1 and also applies an electric charge. As the developing blade 10, a so-called rubber magnet or a plastic magnet, which is formed by mixing a magnetic powder into a resin and then magnetized, and a commonly used ferrite magnet can be used.

The magnetic flux density of the developing blade 10 is determined by the process speed of the image forming apparatus, the relative magnetic permeability of the cylindrical thin film member 17 used for the developing roller 9, and the like. If the process speed increases, it is preferable to increase the contact pressure between the developing blade 10 and the developing roller 9, and if the relative magnetic permeability of the cylindrical thin film member 17 made of a magnetic material is high, the developing blade 10 is provided with a small magnet having a low magnetic flux density. Can be used to regulate the thickness of the toner layer and to provide a charge.

In the present embodiment, the developing blade 10 is formed as a plate-like member which is magnetized in two poles after dispersing magnetic powder in a polyamide resin and integrally molding the same. The developing blade 10 is arranged such that one N pole is in contact with the developing roller 9, and the magnetic flux density of the developing blade 10 is about 80 mT. Then, the developing blade 10 was brought into contact with the toner at a linear pressure of 13 g / cm to regulate the thickness of the toner layer and to charge the toner.

(Toner) Regarding the shape of the non-magnetic one-component toner T accommodated in the developing device 4, even if the toner has irregularities formed by a pulverization method or the like, it can be substantially rested by a polymerization method or the like. There is no problem in using toner. However, the use of a substantially spherical toner facilitates the rolling of the toner at the contact portion between the developing roller and the photosensitive drum, so that the toner is uniformly friction-charged, and the toner is applied to non-image areas around fog and characters. It is possible to reduce so-called scatter, which is attached, and the uniformity of an image is improved.

The spherical degree of the toner is determined by the shape factor SF of the toner.
It can be expressed using -1 and SF-2. SF-1, SF-2
Is a 100 sample toner image randomly sampled using Hitachi FE-SEM (S-800), the image information is introduced into the Nicole image analysis device (Luzex3) via the interface and analyzed. Defines the value obtained from the formula.

[0046]

(Equation 1) MXLNG: Absolute maximum length AREA: Toner projected area PERI: Perimeter The shape factor SF-1 of this toner indicates the degree of sphericity. If it is larger than 140, it gradually changes from spherical to irregular. SF-2 indicates the degree of unevenness. If it is larger than 120, the unevenness of the toner surface becomes remarkable.

The spherical toner particles are formed by a polymerization method, whereby toner particles having a more spherical shape can be obtained. In particular, with respect to the toner particles formed by polymerizing such a portion of the toner particle surface, a necessary portion is formed as a pre-toner (monomer composition) particle in a dispersion medium by a polymerization reaction.
A considerably smoothed version can be obtained.

In the present invention, in order to simultaneously lower the melting point of the toner particles for the purpose of facilitating the production of the spherical toner particles and saving energy, the spherical toner particles have a core / shell structure and the shell portion is formed by polymerization. Is preferred. The function of the core / shell structure is, of course, that the anti-blocking property can be imparted without impairing the excellent fixability of the toner particles. This is because the polymerization of only a part facilitates the removal of the residual monomer in the post-treatment step after the polymerization step.

The main component of the core is preferably a substance having a low softening point, and more preferably a compound having a main maximum peak value of 40 to 90 ° C. measured according to ASTM D3418-8. If the maximum peak is less than 40 ° C., the self-cohesive force of the low softening point substance becomes weak, and as a result, the high temperature offset resistance becomes weak, which is not preferable. On the other hand, when the maximum peak exceeds 90 ° C., the fixing temperature becomes high, which is not preferable. Further, in the case of obtaining a toner by a direct polymerization method, when the temperature of the maximum peak value is high due to granulation and polymerization in an aqueous system, a substance having a low softening point mainly precipitates during granulation, and a suspension system is formed. It is not preferable because it inhibits.

For the temperature measurement of the maximum peak value, for example, DSC-7 manufactured by Perkin Elemer Co., Ltd. is used. The temperature correction of the device detection unit uses the melting points of indium and zinc, and the heat quantity correction uses the heat of fusion of indium. An aluminum pan was used as a sample, an empty pan was set as a control, and measurement was performed at a heating rate of 10 ° C./min.

Specific examples of the low softening point substance include paraffin wax, polyolefin wax, Fischer-Tropsch wax, amide wax, higher fatty acid, ester wax, derivatives thereof, and graft / block compounds thereof. .

The low softening point substance is added to the toner particles in an amount of 5 to 5%.
It is preferable to add 30% by weight. If the addition is less than 5% by weight, it takes a burden to remove the residual monomers described above. If the addition exceeds 30% by weight, coalescence of toner particles is likely to occur during granulation even in the production by polymerization method. ,
Those having a wide particle size distribution were easily formed and were unsuitable.

Further, it is preferable that the surface of the toner particles is coated with an external additive so that the influence of the photosensitive member charging member is released to a certain external additive. External additive coverage of surface is 5-99
%, More preferably 10 to 99%. The external additive coverage on the toner particle surface was determined by Hitachi's FR-SEM (S-800
), 100 toner images are randomly sampled, and the image information is introduced into an image analyzer (Luzex3) manufactured by Nicole via an interface. Since the brightness of the image information is different from that of the toner particle surface portion and that of the external additive portion, the image information is binarized and converted into an external additive portion area S _G and a toner particle portion area (including the external additive portion area) _ST . And calculated by the following equation.

[0054]

(Equation 2) The external additive used in the exemplary embodiment preferably has a particle diameter of 1/10 or less of the weight average diameter of the toner particles from the viewpoint of durability when added to the toner particles. The particle size of the additive means the average particle size of the toner particles obtained by observing the surface of the toner particles with an electron microscope. Examples of the external additive include metal oxides (such as aluminum oxide, titanium oxide, strontium titanate, cerium oxide, magnesium oxide, chromium oxide, tin oxide, and zinc oxide), nitrides (such as silicon nitride), and carbides (such as carbonized). Silicones, etc., metal salts (calcium sulfate, barium sulfate, calcium carbonate, etc.), fatty acid metal salts (zinc stearate, calcium stearate, etc.), carbon black, silica, etc. are used.

These external additives are used in an amount of 0.01 to 10 parts by weight, preferably 0.05 to 10 parts by weight, based on 100 parts by weight of the toner particles.
5 parts by weight are used. These external additives may be used alone or in combination of two or more, and those subjected to a hydrophobic treatment are more preferable.

When the amount of the external additive is less than 0.01 part by weight, the fluidity of the one-component developer is deteriorated, and the transfer and development efficiency is reduced. As a result, so-called scattering occurs in which the developer scatters around the image density unevenness and the image area. If the amount exceeds 10 parts by weight, an excessive amount of the external additive adheres to the photosensitive drum or the developing roller, thereby deteriorating the chargeability of the developing material or disturbing the image.

The non-magnetic one-component toner T according to the present embodiment
Manufacturing will be described. 0.1M-Na in 710g of ion exchange water_Three
PO_FourAfter charging 450 g of the aqueous solution and heating to 60 ° C, the TK homo
Using a mixer (manufactured by Tokushu Kika Kogyo) at 12,000 rpm
Stirred. 1.0M-CaCl _Two68 g of aqueous solution is gradually added
And Ca_Three(PO_Four)_TwoWas obtained. On the other hand, (monomer) styrene 165 g n-butyl acrylate 35 g (colorant) carbon black 15 g (charge control agent) salicylic acid metal compound 3 g (polar resin) saturated polyester 10 g (acid value 14, peak molecular weight; 8,000) (release agent ) Ester wax (melting point 70 ° C) 50g Heat the above formulation to 60 ° C and use TK homomixer (specialized
Dissolve and disperse uniformly at 12,000 rpm using
Was. The polymerization initiator 2,2'-azobis (2,4-dimethyl
Dissolve 10 g of relonitrile) to prepare a polymerizable monomer composition.
It was adjusted.

The polymerizable monomer composition was charged into the aqueous medium, and stirred at 10,000 rpm for 10 minutes with a TK homomixer at 60 ° C. in an N2 atmosphere to form a polymerizable monomer composition. Granulated. Thereafter, the temperature was raised to 80 ° C. while stirring with a paddle stirring blade, and the reaction was performed for 10 hours. After the completion of the polymerization reaction, the remaining monomers were distilled off under reduced pressure. After cooling, hydrochloric acid was added to dissolve the calcium phosphate, followed by filtration, washing with water and drying to obtain colored suspended particles (toner particles). The obtained toner particles are
A core part mainly composed of wax and a shell part composed mainly of resin (resin synthesized by polymerization of a polymerizable monomer) covering the core part are measured by a tomographic method of toner using a transmission electron microscope (TEM). And a core / shell structure having a core / shell portion.

A one-component developer was prepared by mixing 100 parts by weight of the obtained toner particles and 2.2 parts by weight of a hydrophobic fine silica powder having a specific surface area of 200 m ² / g by the BET method. The external additive coverage of the one-component developer was 85%, and the particle size of the silica fine powder was about 50 nm in surface observation of the toner particles by an electron microscope (magnification: 100,000 times). . At this time, the one-component developer has a shape factor SF-1 of 115.
Has a shape factor SF-2 of 110 and a weight average particle size of 6.0 μm.
m.

(Supply Roller) In order for the one-component non-magnetic toner T accommodated in the developing device 4 to adhere to the developing roller 9, the toner T must be rubbed between the supply roller 11 and the developing roller 9 to apply a charge. Must. As a material for the supply roller 11, a known material such as urethane foam rubber or EPDM rubber foam is used. In the present embodiment, the urethane foam rubber is rotated counterclockwise with respect to the developing roller 9.

Next, a contact state between the developing roller 9 and the developing blade 10 and other members in the developing device 4 is shown in FIG.
This will be described with reference to FIG.

In FIG. 4, the hollow portion in the developing roller 9 is formed to be larger than the maximum developing width W0, that is, the maximum width in which the toner is developed on the photosensitive drum, and narrower than the toner carrying area W1. The hollow portion of the developing roller 9 is always in contact with the maximum developing width W0 of the photosensitive drum 1, whereby the contact pressure of the developing roller 9 against the photosensitive drum 1 becomes substantially uniform over the entire surface.

The supply roller 11 is in contact with the thin film holding member 16 such that the end of the supply roller 11 always faces the thin film holding member 16, and is arranged so as to perform uniform toner coating. If the entire surface of the supply roller 11 comes into contact with the hollow portion of the developing roller 9 as shown in FIG.
Only the repulsive tension (arrow S) of the cylindrical thin film member 17 acts on the pressing force of the developing roller 9, the hollow portion is largely dented, and wrinkles and scratches are easily generated on the surface of the cylindrical thin film member 17, and the durability is high. Will also decrease.

On the other hand, as shown in FIG.
When the supply roller 11 pushes the developing roller 9, the repulsive tension of the cylindrical thin film member 17 (arrow S) and the elastic repulsion of the thin film holding member 16 Power will work. Therefore, not only the developing roller 9 and the supply roller 11 can be easily rubbed, but also the reliability with respect to durability is improved.

The state of contact of the developing roller 9 with the supply roller 11 is the same for the photosensitive drum 1, and the contact pressure between the photosensitive drum 1 and the developing roller 9 is reduced. Although the toner T is interposed between the developing roller 9 and other members, since the contact pressure is dispersed by the cylindrical thin film member 17, the toner T
Only a small force works. As a result, there is no possibility that a problem will occur even if the toner is used for a long time without deterioration and fusion of the toner.

Since a magnetic force acts between the developing blade 10 and the cylindrical thin film member 17, they attract each other, and a necessary contact pressure can be obtained even with a small amount of penetration as shown in FIG. By these, the developing roller 9 and the developing blade
A contact pressure sufficient to charge the toner is provided at a contact portion with the photoconductor 10, while a contact pressure at the contact portion between the developing roller and the photosensitive drum 1 can be reduced.

As described above, since the developing blade 10 does not require a large amount of penetration, even if the end of the developing blade 10 reaches the thin film holding member 16 like the supply roller 11, it does not reach the thin film holding member 16 but only the hollow portion. You may abut. However, when abutting only on the hollow portion, it is necessary to perform positioning so that the amount of entry does not become excessive.

In this embodiment, although the cylindrical thin film member 17 is used, the driving thereof does not depend on the frictional force, so that the slip between the shaft member and the thin film member occurs as shown in the conventional example. There is no fear. In addition, since the supply roller 11 is disposed so that the end thereof reaches the position facing the thin film holding member 16, the toner remaining after development is removed by the supply roller 11, and then the sufficiently frictionally charged toner is placed on the development roller 9. The image can be carried, and there is no possibility that the density of the image becomes non-uniform or a ghost occurs, and a high-quality image can be output for a long period of time.

(Operation) The operation of developing the electrostatic latent image on the photosensitive drum 1 using the developing device 4 having the above configuration will be described. In FIG. 2, the photosensitive drum 1 is uniformly charged to -600 V by the primary charger 2, and the potential of the exposed portion of the light emitting element 3 drops to about -50 V, forming an electrostatic latent image. You.

The non-magnetic one-component toner T accommodated in the developing device 4 is carried to the vicinity of the contact portion between the developing roller 9 and the supply roller 11 while being stirred by the stirring member 12. here,
The developing roller 9 rotates in the direction of arrow Y at a peripheral speed of 41 mm / sec, and the supply roller 11 rotates in the direction of arrow Z opposite to the developing roller 9 at a peripheral speed of 25 mm / sec. The non-magnetic one-component toner T is appropriately triboelectrically charged at the contact portion and is carried on the developing roller 9.

The carried non-magnetic one-component toner T is carried to the contact portion of the developing blade 10. At this time, since a magnetic force acts between the developing blade 10 and the cylindrical thin film member 17 of the developing roller 9, the flexible cylindrical thin film member 17 is attracted to the developing blade 10 side and frictionally rubs the toner. A sufficient contact pressure for charging can be obtained. As a result, the non-magnetic one-component toner T carried on the developing roller 9 is friction-charged again by the cylindrical thin-film member 17 and the developing blade 10 and the layer thickness is regulated, so that the toner T has a sufficient charge.

Here, about 0.4 mg / cm ² of non-magnetic one-component toner T passes through the contact portion between the developing roller 9 and the developing blade 10 and is carried to the contact portion between the developing roller 9 and the photosensitive drum 1. The photosensitive drum 1 is in the same direction as the developing roller 9, that is, the arrow X
At the peripheral speed of 27 mm / sec, and the non-magnetic one-component toner T is applied with the applied DC voltage (−350 V
) To develop the electrostatic latent image on the developing roller 9.

At this time, the contact width between the developing roller 9 and the photosensitive drum 1 is about 1.5 to 2 mm. This is substantially determined by the hardness of the thin film holding member 16 existing at the end of the developing roller 9. That is, the contact pressure between the developing roller 9 and the photosensitive drum 1 and the resilience of the thin film holding member 16 are balanced.

Here, the thin film holding members at both ends of the developing roller 9
Although the contact pressure increases at a position facing the area 16, the area where the non-magnetic one-component toner T is formed (the maximum developing width W in FIG.
In (0), since the inside of the developing roller 9 is hollow, the force repelling the contact pressure is only the tension of the cylindrical thin film member 17,
As a result, the contact pressure is very low. Therefore, there is no possibility that the photosensitive drum is damaged due to the high contact pressure, and there is no problem that the formed image is rubbed and disturbed.

Further, the toner T remaining on the developing roller 9 without contributing to the development passes through the blowout prevention sheet 13 and is removed by the supply roller 11. Here, since the supply roller 11 can be brought into contact with a predetermined pressure, a ghost due to insufficient removal of the residual toner does not occur.

As described above, the hollow developing roller 9 composed of the cylindrical thin film member 17 having flexibility and magnetism and the thin film holding members 16 integrated at both ends of the cylindrical thin film member 17 with the shaft member 15 is provided. , Developing blade 10 having a magnetic pole
In the contact portion with the developing blade 10, it is possible to regulate the layer thickness of the toner with a sufficient contact pressure and to provide a necessary electric charge at the contact portion with the developing blade 10. Can reduce the pressure applied to the toner. Therefore, a high-quality image can be output stably and continuously with a simple configuration.

[Second Embodiment] Next, an image forming apparatus and an image forming method according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 7 is a schematic configuration diagram of an image forming apparatus according to the present embodiment, and FIG. 8 is a schematic configuration diagram of a developing roller.
About the part which the explanation overlaps with the first embodiment,
The same reference numerals are given and the description is omitted.

In the first embodiment, the cleaning device 6 removes the toner T remaining on the photosensitive drum 1 without being transferred. On the other hand, in the present embodiment, the cleaning device is omitted, and a so-called simultaneous development and cleaning device is used in which the transfer residual toner on the photosensitive drum 1 is collected by the developing roller.

In order to carry out the simultaneous development cleaning, the transfer residual toner T ′ must be collected by the developing roller. This is because the overcharged and reversely charged toner T ′ is brought into contact with the photosensitive drum 1 and the developing roller 9. This is possible by using negatively charged toner T charged to an appropriate amount on the surface. To achieve this, a wider contact area is required.

Therefore, in this embodiment, the developing roller
The thin film holding member 20 constituting 18 is made of foamed elastic rubber having low hardness, and the cylindrical thin film member 21 is made of a resin having a magnetic material on the back surface, and is resistant to wrinkles and twists and has excellent flexibility. And Further, the use of substantially spherical toner similarly to the first embodiment contributes to the reduction of transfer residual toner at the time of transfer.

The developing roller 18 shown in FIG. 8 comprises a shaft member 19, a flexible cylindrical thin film member 21, and elastic thin film holding members 20 disposed at both ends of the cylindrical thin film member 21. First, the possible forms of the developing roller 18 will be described.

The material of the thin film holding member 20 is formed by adding a foaming agent to a material having elasticity such as a rubber elastomer such as silicone rubber and foaming the material. In addition to silicone rubber, many elastomers such as urethane rubber, ethylene / propylene rubber (EPDM rubber), natural rubber, and styrene / butadiene rubber can be foamed and used as low hardness foamed rubber.

The hardness of the rubber / elastomer was measured by a JIS A rubber hardness tester because it was a solid rubber in the first embodiment. However, in the case of foamed rubber, a JIS A rubber hardness meter is not suitable for the measurement, and thus the measurement was performed using an Asker C hardness meter manufactured by Kobunshi Keiki Co., Ltd.

According to this, the hardness of the rubber / elastomer is
Those having a hardness of 15 to 40 degrees (Asker C) or less can be suitably used. When the rubber hardness is 40 degrees or higher (Asker C) or more, the advantage as a foamed rubber is reduced, and the meaning of foaming is reduced. Hardness is 15 degrees (Asker C)
Below, the diameter of the foamed cell becomes large, and the durability due to compression or the like becomes difficult, which is not preferable.

As the cylindrical thin film member 21 having magnetism, for example, polycarbonate, polyethylene terephthalate,
A magnetic material is adhered or dispersed in the back surface of either a soft resin sheet made of a resin such as polyamide or a fluorine-based resin, or a sheet in which carbon or metal fine powder is added to the resin. As a result, the cylindrical thin film member 21 having magnetism and large flexibility could be formed.

Further, since the above-mentioned sheet comes into direct contact with the toner T, it is preferable that the charge imparting property to the toner T is large. In the present embodiment, since the negatively chargeable toner T is used, the surface of the cylindrical thin film member 21 may be coated with a silicone resin, a urethane resin, a polyamide resin, or the like, which has a negative charge on the toner T. .

The thickness of the cylindrical thin film member 21 is preferably about 80 to 400 μm because of the soft resin sheet. When the thickness of the cylindrical thin film member 21 is 80 μm or less, the surface of the cylindrical thin film member 21 rubs against the photosensitive drum 1, causing wrinkles and warpage, making it difficult to perform stable development.
On the other hand, when the thickness is 400 μm or more, the flexibility of the cylindrical thin film member 21 is lost, and the result is similar to that of a rigid member. As a result, at the contact portion between the photosensitive drum 1 and the developing roller 18, Even with a low hardness elastic member, it is difficult to make contact with light pressure.

In this embodiment, the thin film holding member 20 is formed of silicone sponge rubber to have an inner diameter of φ6 and an outer diameter of φ14. A foaming agent and conductive carbon black are added to the silicone rubber, which is a material, and the silicone rubber is extruded into a cylindrical shape, subjected to primary vulcanization by a steam vulcanization method, and then to secondary vulcanization. Was. afterwards,
The film was cut into a width of about 10 mm to obtain a thin film holding member 20. The obtained thin film holding member 20 had a rubber hardness of 22 degrees (Asker C), a volume resistance of 4e6 Ωcm, and a foam cell diameter of about 200 μm.

The cylindrical thin film member 21 was formed by extruding a polycarbonate resin into a cylindrical shape by extrusion and coating the surface with a polyamide resin. Here, the polyamide resin contains carbon particles to impart conductivity, and has an average surface resistance of 1e5 Ωcm, a film thickness of 160 μm, and a longitudinal width.
Those having a diameter of 240 mm and an inner diameter of φ14 were used. Further, on the back surface of the cylindrical thin film member 21, iron powder having a particle size of about 100 μm was mixed with a binder resin and spray-coated.

Thereafter, the thin film holding member 20 was inserted between the shaft member 19 and the cylindrical thin film member 21 and bonded to form the developing roller 18.
The developing roller 18 has a cylindrical thin film member 21 and a thin film holding member 2O at both ends.
Thus, a substantially cylindrical space surrounded by the cylindrical thin film member, the thin film holding member, and the shaft member is formed inside the cylindrical thin film member.

In manufacturing, the thin film holding member 20 made of foamed rubber is used.
The advantage of the shaft member is that the rubber elasticity is large due to foaming.
When the thin film holding member 20 is inserted between the thin film member 19 and the cylindrical thin film member 21, the thin film holding member 20 can be inserted with its diameter reduced while being compressed, thereby simplifying the manufacturing process. As described above, the developing roller 18 of the present invention has a small number of parts and is easy to manufacture.

Next, the developing blade 22 will be described.
In the first embodiment, the developing blade itself is formed by a magnet.
In this example, a permanent magnet 23 is provided on the back surface of the developing roller contact portion made of a thin metal plate having spring elasticity. As described above, it is also possible to contact the magnetic material such as the permanent magnet 23 via the non-magnetic developing blade. Further, in this configuration, since a thin metal plate having spring elasticity is used for the developing blade 22, there is an advantage that strict positioning accuracy is not required for the set position of the developing blade 22.

By using the developing roller 18 and the developing blade 22 described above, at the contact portion between the developing roller 18 and the developing blade 22, the toner can be sufficiently frictionally charged and the toner amount can be regulated as in the first embodiment. The contact pressure required to perform

Further, by using the developing roller 18 of the present embodiment, the rubber hardness of the foam rubber thin film holding member 20 is low, so that the contact area between the developing roller 18 and the photosensitive drum 1 can be increased while the contact pressure is low. Can be. As described in the first embodiment, since the contact area is substantially determined by the rubber hardness of the thin film holding member, the lower the rubber hardness, the greater the contact area.

In this embodiment, although the roller diameter is smaller than that of the previous embodiment, the contact width is about 2.2.
It was about 3mm. As a result, it is possible to obtain a large contact area required for cleaning simultaneously with development,
The overcharged and reversely charged toner can be negatively charged to an appropriate amount on the contact surface between the photosensitive drum 1 and the developing roller 18, collected in the developing device 24, and used again as the developing toner.

As described above, in this embodiment, the contact width between the photosensitive drum 1 and the developing roller 18 is increased. Here, in the area where the non-magnetic one-component toner T is formed (the maximum developing width W0 shown in FIG. 4), since the inside of the developing roller 18 is hollow, the force repelling the contact pressure is only the tension of the cylindrical thin film member. In addition, the contact pressure further decreases because the contact area increases. Therefore, there is no such a problem that the photosensitive drum 1 is damaged or a formed image is disturbed by rubbing.

In this embodiment, the cylindrical thin film member 21 is used.
However, the present invention is not limited to this. For example, an iron thin film may be attached to the back surface.

As described above, a hollow developing roller 18 constituted by attaching both ends of a cylindrical thin film member 21 having flexibility and magnetism to the shaft member 15 by the thin film holding member 20 made of foamed elastic rubber, and a magnetic pole are provided. By using the developing blade 22, the contact area between the photosensitive drum 1 and the developing roller 18 can be increased, and a high quality image can be stably output as in the first embodiment. The developing roller 18 enables the transfer residual toner on the photosensitive drum 1 to be cleaned.

[0099]

As described above, in the image forming apparatus and the image forming method according to the present invention, a flexible and magnetic cylindrical thin film member is integrated with a shaft member at both ends of the cylindrical thin film member. By using a hollow developing roller composed of a thin film holding member and a developing blade having a magnetic pole, a sufficient contact pressure is used to regulate the layer thickness of the toner at the contact portion with the developing blade, and to control the necessary charge. And the pressure applied to the toner at the contact portion with the photosensitive drum can be reduced. Therefore, it is possible to stably output a high-quality image with a simple configuration.

Further, by using a hollow developing roller in which both ends of a flexible and magnetic cylindrical thin film member are attached to a shaft member by a thin film holding member made of foamed elastic rubber, and a developing blade having a magnetic pole, The contact area between the photosensitive drum and the developing roller can be increased,
As in the first embodiment, it is possible to stably output a high-quality image, and it is possible to clean the transfer residual toner on the photosensitive drum by the developing roller.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a developer carrier according to a first embodiment.

FIG. 2 is an overall configuration diagram of the image forming apparatus.

FIG. 3 is an exploded configuration diagram of a developer carrier.

FIG. 4 is a diagram illustrating the member widths of a developer carrier, an image carrier, and a developer regulating unit.

FIG. 5 is a diagram illustrating a contact state between a developer carrier and an image carrier.

FIG. 6 is a diagram illustrating a contact state between a developer carrier and a developer regulating unit.

FIG. 7 is a schematic configuration diagram of an image forming apparatus according to a second embodiment.

FIG. 8 is a schematic configuration diagram of a developing roller.

[Explanation of symbols]

 A: one-component developer T: non-magnetic one-component toner W0: maximum developing width W1: toner carrying area 1: photosensitive drum 2: primary charger 3: light emitting element 4: developing device 5: transfer roller 6: cleaning device 7 ... Fixing device 8 ... Transfer material 9 ... Developing roller 10 ... Developing blade 11 ... Supply roller 12 ... Stirring member 13 ... Blow-out prevention sheet 14 ... Negative DC voltage 15 ... Shaft member 15a ... End portion 15b ... Center portion 16 ... Thin film holding Member 17: cylindrical thin film member 18: developing roller 20: thin film holding member 21: cylindrical thin film member 22: developing blade 23: permanent magnet 24: developing device

Claims (14)

[Claims] 1. An image carrier on which an electrostatic latent image is formed, a developer carrier carrying a one-component developer, and the one-component developer having at least a magnetic pole on the surface of the developer carrier. And a developer regulating means for regulating the amount of the developer and applying an electric charge to the one-component developer, wherein the developer carrier contacts the image carrier and the electrostatic latent image on the image carrier is provided. In the image forming apparatus which forms an image by developing with the one-component type developer and transferring the image on a recording medium, the developer carrier includes a cylindrical thin film member having flexibility and magnetism, and a shaft member. And a thin film holding member attached near both ends of the shaft member for holding the cylindrical thin film member. The thin film holding member is surrounded by the cylindrical thin film member, the thin film holding member, and the shaft member inside the cylindrical thin film member. Characterized by having a substantially cylindrical space. Image forming apparatus. 2. The image forming apparatus according to claim 1, wherein said thin film holding member is formed of a foamed elastic body. 3. The image forming apparatus according to claim 1, wherein the cylindrical thin film member is formed of a metal thin film made of a magnetic material or a thin film obtained by laminating the metal thin film and a resin thin film. 4. The image forming apparatus according to claim 1, wherein the cylindrical thin film member is formed of a thin film in which a magnetic material is adhered to a back surface of a resin thin film or dispersed in a resin. 5. The image forming apparatus according to claim 1, wherein the width in the longitudinal direction of the image carrier and the developer regulating unit is longer than the longitudinal width of a space formed inside the cylindrical thin film member. The image forming apparatus according to claim 4. 6. The image forming apparatus according to claim 1, wherein the one-component developer has a substantially spherical shape. 7. The one-component developer has a shape factor SF-1.
7. The image forming apparatus according to claim 1, wherein the image forming apparatus has a shape factor SF-2 in a range of 100 to 120. 8. The image forming apparatus according to claim 1, wherein a part or the whole of the one-component developer is formed by a polymerization method. 9. The image forming apparatus according to claim 1, wherein the image forming apparatus has the one-component developer core / shell structure. 10. The main component of the core portion of the core / shell structure is a low softening point substance, and the melting point of the low softening point substance is 40 to
The image forming apparatus according to claim 9, wherein the temperature is 90 ° C. 11. The one-component developer according to claim 1, wherein the one-component developer is a non-magnetic one-component developer.
0. An image forming apparatus according to 12. The image forming apparatus according to claim 1, wherein a coverage of the external additive on the surface of the one-component developer is 5% to 99%. 13. A flexible cylindrical thin film member and a thin film holding member integrated with a shaft member inside both ends of the cylindrical thin film member to rotate and drive a developer carrier having a space therein. While carrying a one-component developer,
After applying the electric charge to the one-component developer while adsorbing the developer regulating unit and the surface of the developer carrier by at least a magnetic force by the developer regulating unit, the surface of the cylindrical thin film member of the developer carrier is removed. An image forming method, wherein development is performed by contacting an image carrier on which an electrostatic latent image is formed. 14. The developing device according to claim 1, wherein the developer carrier visualizes the electrostatic latent image on the image carrier and collects the one-component developer remaining on the image carrier. The image forming method according to claim 13.