JP2002023483A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device whose image forming speed is made high, which can maintain an excellent image over a long term and which can achieve the same effect even in the case of adopting simple device constitution of cleaning simultaneously with developing. SOLUTION: A latent image on a photoreceptor drum 101 having circumferential speed V1 is contact-developed by a reversal developing system by a developing device 103 whose developing roller has circumferential speed V2 by driving at 75 mm/s<=V1<V2. The toner carrying surface of the developing roller 1 is formed of a low frictional material satisfying 0.01<μ<(15/100000)×(R-100)2+0.16 assuming that the roundness of toner defined by a shape factor SF-2 is R for the coefficient of dynamic friction μto SUS in the toner carrying direction of the toner carrying surface in order to restrain the application of excessive momentum from the toner carrying surface and make toner carrying force uniform and constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as an electrophotographic system and an electrostatic recording apparatus using a one-component contact developing method for developing an electrostatic latent image on an image carrier.

[0002]

2. Description of the Related Art There is known an electrophotographic image forming apparatus which reversely develops an electrostatic latent image on an image carrier while a one-component developer is in contact with the image carrier.

In this image forming apparatus, as shown in FIG. 1, the surface of a photosensitive drum 101 is charged to a predetermined potential by a charger 107, and then image information is exposed by an exposure unit 102 so that the photosensitive drum 101 Image information is recorded as an electrostatic latent image. The electrostatic latent image on the photosensitive drum 101 is developed by a one-component developer (toner) supplied by a developing device 103 arranged in contact with the photosensitive drum 101 under the action of a developing electric field formed by a power supply (not shown). And
It is visualized as a toner image.

[0004] The obtained toner image is subjected to a transfer electric field formed between the photosensitive drum 101 and the transfer roller 104 by the action of the transfer electric field.
The toner image is transferred onto the transferred transfer material P, and is then fixed to the transfer material P by heating and pressing by a heat roller of the fixing device 105. The transfer residual toner remaining on the photosensitive drum 101 due to the transfer of the toner image reaches a position where the transfer residual toner contacts the cleaner 106, is mechanically scraped off by a scraper provided inside the cleaner, and is collected in the cleaner.

In developing the electrostatic latent image, a developing device 103 is used to bring toner into contact with the photosensitive drum 101.
The developer carrier provided therein is formed of an elastic body, and is constituted by, for example, a rubber roller, a sponge roller, or the like.

As shown in FIG. 7, a developing device 103 includes a developing container 16 having a developing roller 11 as a developer carrier, a regulating blade 12 as a developer regulating member,
A supply roller 13 as a recovery member, a stirring paddle 14 as a developer stirring / transporting member, and a blowing prevention sheet 15 are provided, and a container 16 contains a non-magnetic toner of a non-magnetic one-component developer. .

[0007] The toner in the developing container 16 is
4, the toner is conveyed to a region near the developing roller 11 and the supply roller 13, and the conveyed toner once becomes dense in the region near the supply roller 13 as the supply roller 13 rotates. Be transformed into Thereafter, the developing rollers 1 rotating in contact with each other in the counter direction
1 and the supply roller 13 are rubbed and frictionally charged to provide a charged charge.

The toner thus charged is supplied to and carried on the developing roller 11 by receiving a mirroring force from the developing roller 11 by the charged charge.
A regulating blade 12 is in contact with the developing roller 11 in a pressurized state, and the toner carried on the developing roller 11 is regulated by the regulating blade 12 so that the developing roller 1
1 is applied in a thin layer, and by this friction with the surfaces of the developing roller 11 and the blade 12, a charged electric charge sufficient for development is provided.

As described above, the toner to which the charge has been applied is applied to the developing roller 11 in a thin layer, and this is subjected to development. The toner applied to the developing roller 11 but not used for development is peeled off from the developing roller 11 by rubbing by the supply roller 13, and a part of the toner is again supplied by the supply roller 13 together with the newly supplied toner. The developer is supplied to the developing roller 11, and the rest is returned to the developing container 16.

On the other hand, the photosensitive drum 101 is
The toner applied to the developing roller 11 is brought into contact with the photosensitive drum 101 for development. Between the photosensitive drum 101 and the developing roller 11,
A developing electric field is formed by application of a developing bias from a power supply (not shown). Under the action of the developing electric field, the toner on the developing roller 11 is transferred to an electrostatic latent image formed on the photosensitive drum 101. Develop the latent image. Since the toner applied on the developing roller 11 is a thin layer, the developing roller 11 is normally driven to rotate at a higher peripheral speed than the photosensitive drum 101 in order to obtain a sufficient image density by development.

In this type of image forming apparatus, the cleaner 10
In some cases, an independent cleaning device such as 6 is omitted, and a so-called simultaneous development cleaning process is used to clean the transfer residual toner on the photosensitive drum 101 by the developing device 103.

The mechanism for simultaneous development and cleaning uses a developing electric field between the photosensitive drum 101 and the developing roller 11 which comes close to the transfer residual toner on the photosensitive drum 101 to reach a contact position with the developing device 103. Photosensitive drum 1
The toner is transferred from 01 to the developing roller 11 and collected by the developing device 103. The collected toner is used again. This collection also has an effect of promoting collection by a mechanical stripping action due to rubbing between the photosensitive drum 101 and the developing roller 11.

[0013]

However, in the conventional image forming apparatus, noise is sometimes mixed in the obtained image, and the image sometimes lacks uniformity particularly in a halftone portion.

This problem is remarkable when, for example, development is performed using a toner having a smooth surface manufactured by a polymerization method or the like, and it has been found that this problem occurs more frequently as the speed of image formation is increased. . This kind of problem is
When outputting only characters, etc., it is not so noticeable, but a pictorial image including a photo, picture, figure, etc. with a color image formed by superimposing toner images of multiple colors or a halftone or solid part In the case of the output, the image quality is strongly impressed.

According to the study of the present inventors, this problem is:
It was found that this was caused by a combination of the shape of the toner used and the toner conveying force on the surface of the developer carrying member.

[0016] The above problem is caused by the fact that the toner which has been transferred to the latent image, in addition to the noise caused by the "fogging" caused by the toner adhering to the portion other than the latent image on the photosensitive drum, which is conventionally known, There is “dot shape fluctuation” which occurs because the dot shape of the latent image cannot be faithfully and uniformly reproduced, and this is manifested by macroscopically perceived as noise.

As is well known, the above fog is caused by insufficient charging of the toner carried on the developing roller or excessive charging of the toner. This is caused by the fact that it did not have a large charge amount.

On the other hand, the latter dot-shaped fluctuations occur when the developing roller comes into contact with the photosensitive drum at a relative speed and the toner conveying force of the developing roller becomes larger than necessary. On the other hand, when the toner is transferred, an excessive momentum is given to the transferred toner in the rotation direction of the developing roller, and the toner is dragged.
Another cause is that the toner remaining on the developing roller side mechanically rubs against the photosensitive drum side.

To further explain, conventionally, in order to form a uniform toner layer on the developing roller, this type of image forming apparatus employs various methods, for example, using a material having a large friction coefficient on the toner carrying surface. It is general to increase the toner conveying force of the roller.

However, by increasing the toner conveying force, the toner layer is made uniform, while the toner carried on the developing roller becomes excessive in the rotation direction of the developing roller at the contact portion with the photosensitive drum. It becomes easy to have a good momentum. This is because the microscopic toner conveying force at each position in the longitudinal direction of the developing roller has a variation, and when the absolute value of the toner conveying force itself is large, the influence of the variation cannot be ignored. It is.

That is, due to the dispersion of the toner conveying force, a partly excessive toner conveying force acts on the toner, resulting in an excessive momentum. The toner having an excessive momentum moves while being dragged to the original position of the electrostatic latent image in the driving direction of the developing roller, thereby disturbing the dot shape where the toner adheres to the latent image and generating noise. . In addition, since the drag of the toner occurs while having a variation in the longitudinal direction, the uniformity of the toner image is disturbed. In particular, in a halftone in which latent images are discretely distributed, variation in dot shape fluctuation distribution caused by toner disturbance is more easily perceived than in a solid portion or a line portion in which latent images are densely distributed.

Further, in the developing area, only the trace of the toner that has already been transferred remains at the position on the developing roller where the toner transferred to the latent image was previously carried. The transferred toner should not be rubbed.

However, when the conveying force of the developing roller is unnecessarily large, the lower layer of the toner layer on the developing roller (the layer in direct contact with the developing roller) and the upper layer (the lower layer of the toner on the developing roller via the lower toner layer). Layer that is indirectly in contact with
The movement with a gap occurs between and
Since the rearrangement of the toner inside the toner layer occurs, a phenomenon has occurred in which the newly conveyed toner fills the trace even if the trace of the toner is once formed.

For this reason, the toner that has once transferred to the latent image is rubbed by the filled new toner due to the rearrangement of the toner layer on the developing roller, and the disturbance of the toner image is reduced. It happened.

The above phenomenon is remarkably caused when a toner having a smooth surface property is used, due to the rolling property associated with the shape. A toner having a smooth surface has a better rolling property than an irregular toner manufactured by, for example, a pulverization method. Therefore, the toner receives a conveying force from a toner carrying surface and has a momentum in a conveying direction. And acts as a “roller” at the contact portion with the photosensitive drum, thereby generating a rotational motion. For this reason, even if the latent image is once adhered to the latent image by electrostatic force, the rotation is not stopped, and the latent image tends to be dragged in the rotation direction of the developing roller without being settled on the latent image.

Further, the toner having a smooth surface has a characteristic that when applied on a developing roller, it is easy to stabilize in a close-packed state due to its good rolling property. Since the nearby toner moves and fills the missing mark immediately, the effect of the rubbing by the toner is more likely to occur.

The above problem occurs more frequently when speeding up the image formation because the rotation speed of the developing roller increases and the amount of motion imparted to the toner increases.

By the way, in this type of image forming apparatus, as described above, a simple configuration can be achieved by omitting the independent cleaning device and adopting the simultaneous development cleaning process.

However, in order to increase the image forming speed and adopt a simple configuration, it is required to reduce the amount of toner collected by simultaneous cleaning with development. This is because the toner collected by this simultaneous cleaning of development is
Deteriorated by the load associated with a series of image forming processes, some of which accumulate in the developing device without being reused, and are fused or fixed to the components of the developing device, This is because it may cause the functional deterioration of the device. Therefore, it is necessary to reduce the amount of toner to be collected in consideration of the improvement in durability and the extension of life as the image forming speed increases.

The toner to be recovered is obtained by adding the uncharged or reversed polarity toner adhered to the image background portion of the photosensitive drum and the toner remaining after transfer in the previous image formation. The solution to the problem is achieved by transferring the formed toner image with high efficiency and reducing the amount of toner attached to the background. When this problem is solved, the amount of toner adhering to the image background is automatically reduced,
Since image noise due to fogging is suppressed, image quality is improved.

Accordingly, an object of the present invention is to increase the image forming speed so that a good image can be maintained for a long period of time, and the same effect can be obtained even when a simple apparatus configuration by simultaneous cleaning with development is adopted. To provide an image forming apparatus capable of achieving the above.

[0032]

The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention provides:
An image carrier, and a developing device, wherein the developing device carries and transports the toner of the one-component developer, a developer carrier in contact with the image carrier, and a developer carrier on the developer carrier. A regulating member that regulates the toner to a thin layer, and under the action of a developing electric field formed between the developer carrier and the image carrier, the electrostatic latent image on the image carrier is actuated by the toner. The toner image obtained by the development is transferred from the image carrier to a transfer material, and the peripheral speed V1 of the image carrier and the peripheral speed V2 of the developer carrier are 75 mm / sec ≦ V1 <V2. In the image forming apparatus, the toner carrying surface of the developer carrying member is SUS in the toner conveying direction by the toner carrying surface.
And the circularity of the toner defined by the shape factor SF-2 as R, 0.01 <μ <(15/100000) × (R-100) ² +0.16 (1) An image forming apparatus formed of a low friction material satisfying the following.

According to the present invention, the toner may have R ≦ 14.
It has a smooth surface shape of zero. The developer carrier,
An elastic layer and a surface layer were formed on a substrate, and the surface layer was formed of a material satisfying the above-mentioned formula (1) for the dynamic friction coefficient μ. The material is located on the opposite polarity side to the triboelectric polarity of the toner in the triboelectric series. Under the action of the developing electric field, development of the electrostatic latent image on the image carrier by toner on the developer carrier and collection of the transfer residual toner on the image carrier to the developer carrier Do,
A development simultaneous cleaning process is performed. The toner is a non-magnetic toner. The developer carrier is a roller-shaped developing roller. The image carrier is a drum-shaped photosensitive drum.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Embodiment 1 FIG. 1 is a schematic structural view showing an embodiment of the image forming apparatus of the present invention. The image forming apparatus performs image formation by performing development using a one-component contact development system.

The most characteristic point of this image forming apparatus is that the toner of the one-component developer carried on the developing roller 1, which is a developer carrier, is prevented from being given an excessive momentum, The toner carrying surface of the developing roller 1 is adjusted to have a dynamic friction coefficient μ within a predetermined range in accordance with the circularity of the surface of the toner particles to be used in order to make the conveying force with respect to the toner uniform and constant.
It is formed of a low friction material having

According to the study of the present inventors, the conveying force and the momentum applied to the toner from the developing roller are correlated with the kinetic friction coefficient μ of the toner carrying surface of the developing roller, and according to the surface shape of the toner particles, This is the result of the knowledge that the contribution of the toner to the development is different. Details will be described later.

As shown in FIG. 1, the image forming apparatus includes a photosensitive drum 101, a charger 107, an exposing unit 102, a developing unit 103, a transfer roller 104, a cleaner 106, and a fixing unit image 105. The forming speed, that is, the rotation of the photosensitive drum 101 is set to the peripheral speed (V1) = 100 to 2
Developing device 10 driven at 50 mm / sec and placed in contact therewith
Rotation of the developing roller 1 at a peripheral speed of 120 to
The electrostatic latent image on the photosensitive drum 101 is reversely developed with the toner on the developing roller 1 by driving at a peripheral speed (V2) of 200%.

The details of the image forming process have already been described in the section of the prior art, so that the description will be omitted.

As shown in FIG. 2, the developing device 103 uses non-magnetic toner (non-magnetic one-component developer). A regulating blade 2 as a member, a supply roller 13 as a developer supply / recovery member, a stirrer stirring / conveying member (stirring paddle) 4, and a blowout prevention sheet 5 are provided. Have been.
The developing roller 1 has elasticity.

The developing process of the present developing device is basically the same as that of the developing device shown in FIG. 7, so that the description of the details of the developing process is omitted.

The non-magnetic toner used in this embodiment is a negatively-charged non-magnetic polyester toner manufactured by a pulverizing method, and has a surface smoothed by a heat treatment during the manufacturing process.

The shape of the toner is represented by a circularity R (R≡SF-2) defined by a shape factor SF-2, and specifically, a smoothness within a range of circularity R = 113 to 130. Those having an appropriate surface shape were used. Details of the shape factor will be described later.

The non-magnetic toner is basically manufactured by kneading and pulverizing toner raw materials. A resin, a release agent composed of a material having a low softening point, a colorant, a charge control agent, and the like are mixed with a pressure kneader or an extruder. After uniformly dispersing using a media disperser, it is crushed to a desired toner particle size by colliding with a target under a mechanical or jet stream, then smoothing the surface through heat treatment, and further through a classification process. This is a non-magnetic toner having a volume average particle diameter of 6 to 8 μm, which has a desired particle size distribution. Due to the surface smoothing performed in the middle, the surface shape is smooth without protrusions as seen in toner obtained only by the conventional pulverization method.

Of course, toners manufactured by other manufacturing methods, such as various polymerization methods, may be used.

In the present invention, the volume average particle diameter of the toner was measured by the following method.

As a measuring device, a call counter TA-II is used.
Using a mold (manufactured by Coulter), a personal computer is connected via an interface (manufactured by Nikkaki) that outputs the number distribution and volume average distribution, and data processing is performed.

The measuring method is as follows. A 1% aqueous solution of NaCl is prepared as an electrolytic solution using primary sodium chloride, and 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the electrolytic solution. The toner of the measurement sample was added in an amount of 0.5 to 50 mg, and the electrolytic solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes with an ultrasonic disperser, and the particle size distribution was measured using the Coulter Counter TA-II. , And determine the volume distribution. At that time, an aperture of 100 μm is used, and the particle size distribution range is 2 to 40 μm. The volume average particle size of the sample is calculated from the number distribution and the volume distribution obtained as described above.

If necessary, known fluidity-imparting agents, lubricants, abrasives, cleaning aids, resistance regulators, charge control agents, and the like can be externally added to the toner. The rate is preferably 5 to 99%, more preferably 10 to 9%.
9%.

In the present invention, the coverage of the external additive is defined as follows.

Hitachi FE-SEM (S-800)
, 100 toner particle images are randomly sampled, and the image information is introduced into an image analyzer (Lusex3, manufactured by Nicole) via an interface. The obtained image information is binarized by utilizing the difference in brightness between the toner particle surface portion and the external additive portion, and the area SG of the external additive portion and the area of the toner particle portion (the area of the external additive portion) (Including area), and is calculated from the formula of external additive coverage (%) = (SG / ST) × 100.

As the external additive, from the viewpoint of durability when added to the toner, it is 1/1 of the weight average particle size of the toner particles.
The particle size is preferably 0 or less. In the present invention, the particle diameter of the external additive means an average particle diameter thereof obtained by observing the surface of the toner particles with an electron microscope.

Examples of the external additive include metal oxides (aluminum oxide, titanium oxide, strontium titanate, cerium oxide, magnesium oxide, chromium oxide,
Tin oxide, zinc oxide, etc., nitride (silicon nitride, etc.), carbide (silicon carbide, etc.), metal salt (calcium sulfate, barium sulfate, calcium carbonate, etc.), aliphatic metal salt (zinc stearate, calcium stearate, etc.) , Carbon black, silica and the like are used.

These external additives are used in an amount of 0.01 to 10 parts by weight, preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the toner.
0.5 to 5 parts by weight are used. These external additives may be used alone or in combination. Those subjected to a hydrophobizing treatment are more preferable.

As mentioned earlier, the shape factor SF-2 is used to indicate the surface shape of the toner, but there are SF-1 and SF-2 as the shape factors. Specifically, using an FE-SEM (S-800) manufactured by Hitachi, Ltd., and a magnification of 500
One hundred randomly enlarged toner particle images are sampled at random, and the image information is introduced into an image analyzer (Lusex3) manufactured by Nicole via an interface, analyzed, and a value calculated from the following equation is calculated. Defined.

SF-1 = ｛(MXLNG) ² / ARE
A｝ × (π / 4) × (100) SF-2 = {(PERI) ² / AREA} × (1/4
π) × (100) where AREA: the projected area of the toner, MXLNG: the absolute maximum length, PERI: the circumferential shape factor SF-2, that is, the closer the circularity R is to 100, the closer to the surface shape of a true sphere, On the other hand, when SF-2 (circularity R) is larger than 140 and the ratio of SF-2 / SF-1 exceeds 1.0, the surface of the toner particles is smooth. Rather, it has a large number of irregularities. Incidentally, the shape factor SF-1 corresponds to the sphericity of the whole toner particles.

There is a relationship between the surface shape of the toner and the transferability. As the force acting on particles such as toner, in addition to the electromagnetic force that is the main force such as the reflection force acting on the charge of the toner itself, other van der Waals forces, droplets attached to the surface And liquid cross-linking force. The accumulation of these forces appears as an adhesive force between the toner and the object. For example, variations in the surface charge density and the like at each part of the toner having an irregular shape (for example, when the charge density is locally high at the protrusions). It is considered that the acting adhesive force (electromagnetic force) is different depending on whether or not it is.

Therefore, the irregular toner does not always exhibit a uniform behavior under a uniform electric field, and this phenomenon is specifically manifested in the transferability. That is, since all of the amorphous toner is not transferred following the electric field, it is difficult to obtain high transferability. On the other hand, a toner having a smooth surface tends to have a uniform surface charge density distribution, and there is little variation in the adhesive force of each toner. Therefore, it is easy to transfer uniformly following the transfer electric field, and has high transferability.

According to the present invention, in the developing roller 1, the toner carrying surface is formed of a material having a low friction coefficient, and the material having the low friction coefficient is the dynamic friction coefficient of the toner carrying surface with respect to the reference material in the toner conveying direction. In the present invention, the dynamic friction coefficient μ for SUS is defined as the circularity (SF-2) of the toner as R, and 0.01 <μ <(15/100000) × (R-100) ² +0.16 (0.16) 1) Satisfies a certain range.

In this embodiment, the developing roller 1 has an outer diameter of 12 mm.
A solid elastic layer made of a low-hardness silicone rubber in which a conductive agent such as carbon is dispersed is provided on a SUS cored bar having a thickness of 2 mm, and a low friction / high releasable particle is provided as a surface layer serving as a toner carrying surface thereon. And a polyamide resin layer having a thickness of about 10 μm in which fluororesin particles are dispersed.
It was formed on a semiconductive elastic roller having a volume resistivity of 0 ³ mm and a volume resistivity of 10 ³ to 10 ⁹ Ωcm.

The hardness of this developing roller is
In order to form a sufficient and uniform contact state with No. 1 and to have a stable developing performance, Asker-C
It should be soft having a hardness of 55 ° or less, preferably in the range of 35 ° to 45 °. In the case of a hard developing roller out of this hardness range, in order to form a uniform contact state with the photosensitive drum 101, it is necessary to increase the contact pressure between them.
The increase in the load on the toner due to the contact promotes the deterioration of the toner, and accompanying this, the performance of the developing roller and the regulating blade tends to deteriorate, which is not desirable.

In addition, it is desirable that the solid elastic layer of the developing roller has a thickness of at least 2 mm. If the thickness of the elastic layer is less than 2 mm, deformation of the elastic layer at the contact portion with the photosensitive drum 101 is hindered, and an uneven contact state is formed, which is not desirable.

The elastic layer as described above may be made of natural rubber, NBR, fluorine rubber, urethane rubber,
It may be formed from low-hardness rubber or foam such as hydrin rubber or acrylic rubber, or a combination thereof.

As described above, in the configuration in which the surface layer is provided on the elastic layer, the elasticity of the developing roller and the toner carrying function can be separated, so that the restrictions on the material used are reduced, and high functionality can be easily achieved. You can have. As a similar developing roller form, a tube-shaped, film-shaped resin or metal, an alloy or a carbon-based fiber or other surface layer on the elastic layer,
A configuration in which a functional film is provided on the elastic layer is also possible.

In this embodiment, as described above, the surface layer serving as the toner-carrying surface is made of fluororesin particles so that the dynamic friction coefficient μ of the toner-carrying surface with respect to SUS in the toner conveying direction is within the range of the expression (1). Formed of a polyamide-based resin in which is dispersed. Specifically, the circularity R of the toner to be used is R =
A composition having a dynamic friction coefficient μ = 0.18 with respect to 113 to 130 was used.

When the dynamic friction coefficient μ is μ ≧ (15/10000)
In the case of 0) × (R-100) ² +0.16, an excessive amount of momentum is likely to be given to the toner carried on the developing roller, and the toner conveying force varies in the longitudinal direction of the developing roller. Easy and undesirable. μ ≦ 0.01
In this case, it is difficult to form the toner carrying surface itself, which is not practical.

In the present invention, the dynamic friction coefficient μ was measured using stainless steel (SUS) as a reference material as described above.
The dynamic friction coefficient μ is measured as shown in FIG.

The developing roller 1 as an object to be measured is fixedly set on a rotating shaft and set on a peripheral surface of the developing roller. A stainless steel thin plate 110 having a thickness of 0.03 mm and a weight of W2 is provided as a reference material.
Is hung at a portion divided into two, and one end of the thin plate 110 is horizontally attached to the digital force gauge 112, and a weight 116 having a weight W1 is attached to the other end of the thin plate 110 and pulled in the vertical direction. The developing roller 1 is installed so as to be in contact with the surface of the developing roller 1 over θ = 90 °. The digital force gauge 112 is adjusted to a value of 0 at the time of no load in which neither the stainless steel plate 110 nor the weight W1 is attached.

Next, with the stainless steel thin plate 110 and the weight W1 attached, the digital force gauge 112 is used.
Is stable, the developing roller 1 is rotated counterclockwise as shown by the arrow R in the figure to rub against the stainless steel sheet 110, and the force gauge 112 slides between the developing roller 8 and the stainless steel sheet 110 at this time. The rubbing force (ie, the conveying force) is measured. A measured value (analog output value) from the force gauge 112 is sampled at a frequency of 10 Hz by a recorder, the sampled data is introduced into a computer 114, and a dynamic friction coefficient μ is calculated by the following equation (2).
This is performed for one round of the developing roller 1, and the average value is defined as the dynamic friction coefficient of the developing roller 1. In the actual measurement, a weight of W1 = 100 g was used.

Μ = 1 / θ × lnF / W (2) where W: W = W1 + (（) W2, F: average value of the measured values of the rubbing force in one circumference of the developing roller The reason why the dynamic friction coefficient of the surface of the developing roller 1 was measured using a stainless steel thin plate as a reference material is as follows.

The toner on the developing roller is carried in a thin layer filled on the carrying surface, and can be handled macroscopically as a film-shaped continuous body. Although the surface layer of the toner layer has irregularities depending on the degree of filling of the toner, the toner rolls and slips, so that the macroscopic surface property of the toner layer can be approximated by a model with a smooth surface. Therefore, a SUS sheet, which is a metal sheet, was used as a reference material for measuring the dynamic friction coefficient μ.

According to the study of the present inventors, when a resin film or a thin metal plate other than SUS is used as the reference material, the friction and mechanical properties (elastic modulus, rigidity, expansion, etc.) of the reference material itself are used. , Etc.), the contrast of the measured amount may not be large, or the reproducibility may be poor. As described above, it was concluded that the use of the SUS thin plate was appropriate, and the consistency with the actual one was high.

The material for the toner carrying surface of the developing roller 1 is not limited to the above-mentioned combination of polyamide resin and fluororesin particles. For example, a resin such as a fluororesin or a silicone resin having low friction even if the resin alone, or Ni, Sn, Cu, Zn, Pb, Au, Ag, Mo,
A single metal such as B, an alloy or oxide containing the same, or a carbon-based fiber such as carbon fiber or graphite fiber can be used in combination of any one or two or more kinds. Resins or metals having relatively low friction properties can also be used as long as low friction properties can be achieved by mixing and dispersing low friction materials.

By increasing the surface area of the surface of the developing roller 1, the charge imparting property to the toner is stabilized,
It is preferable that the toner has an appropriate surface roughness so that the toner transport amount can be secured.

In order to impart surface roughness, an elastic layer is formed on the core metal of the developing roller, the surface layer of the elastic layer is polished, and then the resin layer serving as the toner carrying surface is thinned to about 10 μm. It may be formed by a method such as roll coating, spray coating, dipping, or the like.

In this embodiment, the resin layer on the toner carrying surface
Fluororesin particles are dispersed as particles having low friction and high releasability. By appropriately selecting the particle size of the particles, irregularities can be formed on the surface layer of the resin layer. That is, in addition to imparting a lower friction property and an improved releasability than the particles, the particles can be used as particles for roughening the surface, and the desired surface roughness can be obtained without polishing the elastic layer. Can be.

As a matter of course, as a surface roughened particle, low friction
Particles different from the highly releasable particles may be newly dispersed.

The surface roughness of the developing roller 1 is such that the volume average particle diameter of the toner used is in the range of 1 to 10 μm.
The ten-point average roughness Rz specified in JIS B0601 is 3
The maximum height Rmax is set to 15 μm. For measuring the ten-point average roughness Rz, a surface roughness tester SE-30H manufactured by Kosaka Laboratory was used.

When Rz is less than 3 μm, the surface area is small, the frictional charge on the toner tends to be nonuniform, and the charge amount distribution of the toner becomes broad.
The ability to follow the electric field is inferior, thereby lowering the developing performance.
Not preferred.

If Rz exceeds 15 μm, the toner near the roller surface of the toner layer carried on the developing roller remains buried in the unevenness on the surface. The amount is undesirably increased, and the amount of uncharged and inverted toner increases. In particular, R
When max exceeds 15 μm, these problems become remarkable because the surface irregularities are too large.

Regulator blade 2 as developer regulating member
Is made of an L-shaped SUS leaf spring.
As shown in (1), it is disposed in contact with the developing roller 1 at the L-shaped edge portion, and regulates the toner on the developing roller 1 to form a thin layer having a predetermined layer thickness. The contact pressure at this time is approximately 10
~ 45 g / cm is preferred. When the contact pressure is less than 10 g / cm, the regulating force is insufficient, so that it is difficult to stably regulate the toner to a predetermined layer thickness, and it is easy for the toner to be insufficiently charged. On the other hand, if it exceeds 45 g / cm, the toner tends to deteriorate due to the stress caused by the regulating force, which is not preferable.

The contact pressure (linear pressure) of the regulating blade 2 can be measured as follows. A SUS thin plate having a length of 100 mm x a width of 15 mm x a thickness of 30 µm is used as a drawing plate, and a length of 180 mm x a width of 30 mm x a thickness of 3 is used as a sandwiching plate.
A SUS thin plate of 0 μm is prepared by folding the SUS thin plate so that the length is reduced to half, and a drawing plate is inserted between the folded sandwich plates.
Insert between Then, the spring gauge attached to the pulling plate is pulled, the pulling plate is pulled out at a constant speed, and the load (g) indicated by the spring meter at that time is read. By dividing the value of the spring measurement by 1.5 and converting the unit into a load per cm, the contact pressure of the regulating blade 2, that is, the linear pressure (g / c)
m) is measured.

In the present embodiment, a bent SUS plate spring is used as the regulating blade 2, which is brought into edge contact with the developing roller 1. As long as the contact state can be obtained and mechanical toner regulation can be performed, materials of different types and shapes can be used instead. For example, regulation blade 2
It is possible to use a linear flat metal or resin thin plate, which is brought into surface contact with the developing roller 1. In this case, the contact pressure is 5 to 10 g more than the edge contact.
/ Cm is preferable.

The image forming apparatus of this embodiment is configured as described above.

In this embodiment, the photosensitive drum 1 is set at a peripheral speed of 1
00 mm / sec.
%, The image forming operation was performed about 10,000 times, and various images were output. As a result, even in a pictorial image or the like, a good image excellent in uniformity of the halftone portion was maintained.

Comparative Example In the image forming apparatus of Example 1, a toner having a different circularity R was used for the developing device 103, and a developing roller having a dynamic friction coefficient μ of the surface outside the above-mentioned range was used for the circularity R. Used in combination.

The toner has a circularity R of 113, 120, 140, or 160, which is prepared by changing the heat treatment conditions for smoothing.
Is a seed. The developing roller has a dynamic friction coefficient μ of the toner carrying surface.
To reduce the amount of high release particles dispersed in the resin layer,
μ = 0.25, instead of a urethane-based resin layer having a low frictional property, μ = 0.45, a silicone rubber elastic layer without a resin layer,
= 0.8 and three types.

Using the combination of the toner circularity R and the dynamic friction coefficient μ of the toner carrying surface of the developing roller, an image was formed under the same conditions as in Example 1 using the developing device for development. In the above, although the output of an image such as a character could be within the allowable range, the output of a pictorial image was generally defective.

Comparison between Example 1 and Comparative Example FIG. 4 shows the circularity R of the toner used for image formation and the dynamic friction coefficient of the toner carrying surface of the developing roller in the image forming apparatuses of Example 1 and Comparative Example. The correlation with μ is shown.

FIG. 4 shows that an evaluation image including a pictorial image is output during the image formation of about 500 to 1000 times, and the image output is output at an image formation speed of 38,5,5.
0, 75, 100, 300 mm / sec.
The obtained evaluation image was evaluated, and a combination of R and μ when a good image was obtained with excellent uniformity of the halftone portion without noise, and R and μ when an image failure occurred even once. The figure shows a segment curve (section curve) that bisects the combination of the above and the image formation speed as a parameter.

An area located below each segment curve indicates that good image formation is performed, and an area located above each section curve indicates that an image defect occurs. A region A surrounded by a dotted line is a range defined by the present invention between the circularity R of the used toner and the dynamic friction coefficient μ of the developing roller toner carrying surface.

As shown in FIG. 4, in the first embodiment, the toner carrying surface of the developing roller is
(= 113 to 130), it is made of a low friction material having a dynamic friction coefficient μ (= 0.18) in the region A. At least at an image forming speed of 75 mm / sec or more, Each of them is located in an area where good image formation can be performed.

More specifically, FIG. 4 shows that when a toner carrying surface having a large μ is provided, there is a tendency that good image formation is not performed as the image forming speed increases. ing. This is because, as the image forming speed increases, the moving speed of the toner carrying surface increases, and the absolute value of the momentum imparted to the toner increases, so that the toner is formed on the photosensitive drum by development as described above. It is considered that this is because the toner image is likely to be disturbed or the toner is likely to be dragged on the latent image to be transferred.

Further, the value of μ at which a good image can be formed differs depending on the surface shape of the toner to be used. The reason is that the conveying force from the toner carrying surface is not necessarily the momentum of the toner in the conveying direction. Because it is not converted to

The toner having an irregular shape contacts the toner-carrying surface at a plurality of places or comes into surface contact with each other, so that the direction of the acting conveying force and the direction of the momentum generated thereby are shifted. Further, since rotation in an indeterminate direction occurs, the conveying force from the toner carrying surface is not directly converted into the momentum in the toner conveying direction.

On the other hand, the toner having a smooth surface shape comes into almost point contact with the toner carrying surface, so that the direction of the applied conveying force and the direction of the momentum generated thereby are substantially the same. In the direction of travel. In other words, it is considered that the toner having a smooth surface shape tends to have an effect on the toner carrying property of the toner carrying surface, and therefore, μ at which a good image can be formed becomes small.

When the image forming speed is 75 mm / sec or more, the segmentation curve does not change so much as the speed increases, and it seems that the curve is saturated. This is because the toner carrying force is already sufficiently large compared to the magnitude of the toner carrying force on the toner carrying surface, so that the carried toner remains fixed by the force carrying the toner. In other words, since the toner is rotated as a "roller" and slips at the contact portion with the photosensitive drum, it is considered that the toner conveying force that substantially acts reaches a plateau, and the sectional curve shows the same behavior.

Embodiment 2 Another embodiment of the present invention will be described.

In the present embodiment, similarly to the first embodiment, the toner carried on the developing roller is prevented from being given an excessive amount of momentum, and the conveying force for the toner is made uniform and constant. In addition, the toner carrying surface is formed of a low friction material having a dynamic friction coefficient μ within a predetermined range according to the circularity R of the toner to be used. In order to suppress the absolute amount of toner collected in the above, the above-mentioned toner is made into a spherical toner having a smooth surface shape. Large material.

The other structure of the present embodiment is basically the same as that of the first embodiment. Hereinafter, FIG. 1 will be referred to as needed.

In this embodiment, the image forming apparatus controls the image forming speed, that is, the rotation of the photosensitive drum 101 in FIG.
8.3 to 200 mm / sec, and the rotation of the developing roller 1 of the developing device 103 arranged in contact with the photosensitive drum 101 is driven at 160 to 200% of the peripheral speed of the photosensitive drum. The upper electrostatic latent image is reversely developed.

In this embodiment, the toner used in the developing device 103 is a negatively chargeable non-magnetic spherical toner made of a styrene acrylic resin and manufactured by a known suspension polymerization method. Having a smooth surface shape and having a low softening point substance, it has a low melting point,
It has the property of having a low softening point. Of course, a spherical toner obtained by another manufacturing method can be used.

As the spherical toner, a toner having a volume average particle diameter of 4 to 7 μm is used so as to obtain high image quality. This is because, in order to faithfully reproduce a minute electrostatic latent image recorded with a pixel density exceeding approximately 400 dpi, it is necessary to use a toner having a particle size of at least 10 μm or less, particularly with a toner of 7 μm or less. This is because, in the formed image, noise related to graininess, uniformity, and the like is repelled to a low-sensitivity region in terms of human visual characteristics, making it difficult to perceive.

If the particle size exceeds 10 μm, toner fusion to the surface of the photosensitive drum and various members tends to occur.
When the coefficient of variation in the number distribution of toner particles exceeds 35%, the tendency is further enhanced. On the other hand, when the particle diameter of the toner is less than 4 μm, a large amount of untransferred toner is generated on a photosensitive drum or a transfer material due to a decrease in transfer efficiency, which further causes fog and non-uniform unevenness of an image due to poor transfer. Not preferred.

The variation coefficient A for the number of toner particles is calculated from the following equation.

Coefficient of variation A = S / D1 × 100 where S: standard deviation value in the number distribution of toner particles D1: number average particle size of toner particles (μm) Further, the spherical toner has a low softening point substance as a core, It has a so-called core / shell internal structure in which it is coated with an outer horn bark by a polymerization method.

As the low softening point substance used for the core,
In a DSC curve measured by a differential scanning calorimeter,
Those having a maximum endothermic peak in the range of 40 to 130 ° C. when the temperature is raised are used. The measurement of the maximum endothermic peak temperature is A
According to STM D 3418-8, the measurement was performed using DSC-7 manufactured by PerkinElmer. The temperature correction of the device detection unit uses the melting points of indium and zinc, and the correction of the calorific value uses the heat of fusion of indium. An aluminum pan (dish) was used as a measurement sample, an empty pan was set as a control, the temperature was raised and lowered once, a pre-history was obtained, and the measurement was performed at a rate of 10 ° C./min. .

By having the maximum endothermic peak in the above-mentioned temperature range, it greatly contributes to low-temperature fixing, and also effectively develops releasability. As a result, it is not necessary to apply a release agent such as silicone oil to the fixing device, and the configuration of the fixing device can be simplified.

As the above-mentioned low softening point substance, paraffin wax, polyolefin wax, Fischer-Tropsch wax, amide wax, higher fatty acid, ester wax, derivatives thereof, and graft / block compounds thereof can be used. The compounding amount in the toner is preferably 5 to 30% by weight.

[0110] The spherical toner is manufactured by using a transmission electron microscope (TE).
In observing the tomographic plane of the toner particles using M), it is preferable that the wax component is substantially spherical and / or spindle-shaped and dispersed in an island shape without being compatible with the binder resin. By dispersing the wax component as described above and encapsulating it in the toner, it is possible to prevent deterioration of the toner and contamination of the image forming apparatus, etc., so that good chargeability is maintained and dot reproduction is excellent. It is possible to form a damaged toner image for a long period of time. In addition, since the wax component acts efficiently at the time of heating, the low-temperature fixability and the offset resistance can be satisfied.

The characteristic internal structure of the toner particles is identified by observing the cross section. Specifically, after sufficiently dispersing the toner particles in a cold-setting epoxy resin, an atmosphere at a temperature of 40 ° C. The cured product obtained by curing for 2 days is dyed using ruthenium tetroxide and, if necessary, osmium tetroxide in combination, and a flaky sample is cut out using a microtome equipped with a diamond blade. Observe the tomographic morphology of the toner particles by TEM.

In observing the tomographic morphology, a ruthenium tetroxide staining method was used to give a contrast between the materials by utilizing a slight difference in crystallinity between the wax component used and the resin constituting the outer shell. Preferably, it is used. In the toner particles thus observed, it was observed that the wax component was encapsulated in the outer shell resin.

For the spherical toner, the value of the shape factor SF-1 measured by the image analyzer is 100 to 140, and the shape factor SF-
It has a spherical and smooth surface shape such that the value (R) of 2 is 100 to 120. The shape factor SF-1 indicates the sphericity (degree of roundness) of the entire toner particles, and gradually changes from a spherical shape to an irregular shape as the numerical value increases. SF-
2 indicates the degree of unevenness of the toner particles, and as the numerical value increases, the unevenness of the toner surface becomes more remarkable.

The toner having the above-mentioned smooth surface shape is as follows:
Due to its shape, it has good rolling properties, and uniform charging is easily performed in frictional charging. Therefore, the amount of uncharged or reversal toner that causes image fogging is easily reduced, which is advantageous. In addition, since the toner is uniformly charged, the toner has excellent uniform followability with respect to an electric field, so that good developing performance and transfer performance are exhibited. Therefore, it is advantageous even when high image quality is required to reproduce a minute electrostatic latent image, and the amount of untransferred toner can be reduced due to good transferability.

Also in the present embodiment, the toner carrying surface of the developing roller 1 is formed of a material having a low friction coefficient, and the dynamic friction coefficient μ of the toner carrying surface with respect to SUS in the toner driving direction is represented by R, where R is the circularity of the toner. Equation (1), that is, 0.01 <μ <(15/100000) × (R−10
0) ² +0.16 is satisfied.

In this embodiment, the developing roller 1 has an outer diameter of 12 mm.
A solid elastic layer of low-hardness urethane rubber in which a conductive agent such as carbon is dispersed is provided on a SUS cored bar having a thickness of 10 mm, and a silicon-based resin layer having a thickness of 10 μm is provided as a surface layer serving as a toner carrying surface thereon. 20 mm outside diameter, volume resistivity 1
It was configured as a semiconductive elastic roller of 0 ³ to 10 ⁹ Ωcm.
The surface layer of the silicone resin has PMMA as coarse particles.
The particles were dispersed, and the coefficient of kinetic friction μ of the toner carrying surface was set to μ = 0.10 for the circularity R of the toner used in the present embodiment of R = 100 to 120.

In this embodiment, as described above, the material on the toner carrying surface of the developing roller 1 is located on the side opposite to the triboelectric charging polarity of the toner used in the triboelectric series.

In this case, since the charge is applied to the toner by frictional charging, if such a material is used for the toner carrying surface, the charge imparting property of the toner carrying surface is enhanced, and the uncharged or inverted toner is reduced. This makes it possible to improve the developability and reduce the amount of toner adhering to the non-image area, which causes fogging.

Therefore, the material for forming the toner carrying surface is not limited to the above-described one, and different materials can be used. The specific selection of the material is determined based on mutual charge imparting property by frictional charging with the toner. The charge imparting property by triboelectric charging can be measured, for example, by a cascade method according to the following procedure.

As shown in FIG. 5, the measuring apparatus has a funnel-shaped sample container 20 for storing toner sample particles T disposed above a sample plate 21 placed obliquely. Receiving tray 2 for receiving sample particles T
3 and the grounded capacitor 22 is connected to the sample plate 2
1 is connected. The sample plate 21 is formed of the same material as the material used for the surface (toner carrying surface) of the developing roller 1, or is formed by providing the same material on the surface of a conductive substrate such as aluminum.

The sample particles T are obtained by covering the entire surface of the metal powder with the toner resin.
It is prepared by dissolving in an organic solvent such as EK or toluene, stirring and mixing a metal powder having an average particle size of about 100 μm (possible with iron powder or the like) into the obtained toner resin-containing solution, and then removing the organic solvent. did. According to the sample particles thus prepared, it was confirmed by observation with an electron microscope that the toner resin covered the entire surface of the metal powder.

For the measurement, the sample particles T are dropped on the sample plate 21 from the slit 20a provided at the lower end of the funnel leg for a predetermined amount for about 10 to 20 seconds.
The particles T are dropped while rolling on the sample 21 inclined about 45 to 60 ° with respect to the horizontal plane. The dropped sample particles T are stored in the tray 23. Due to this drop, the sample particles T are frictionally charged with the sample plate 21, and the sample plate 2
The triboelectric charge applied to the first side is stored in the capacitor 22 from the sample plate 21.

Since the same amount of triboelectric charge as that of triboelectric charge applied to the sample plate 21 is applied to the sample particles T, the amount of electric charge stored in the capacitor 22 is measured, and In this case, the charge imparting property to the toner due to frictional charging of the material of the sample plate 21, that is, the material used on the surface of the developing roller is measured. The amount of electric charge stored in the capacitor 22 is obtained by measuring the potential of both ends of the capacitor and using the capacitance of the capacitor as a product of the potential difference between both ends × the capacitance.

Based on the measurement and evaluation of the charge imparting property of such a material, a charge of a desired polarity (here, a negative polarity) can be applied to the toner to be used, and the amount of charge to be applied is determined to be large. Is preferably used as a material for the toner carrying surface of the developing roller 1.

In addition to the above measurement / evaluation methods, for example,
The charge amount of the toner carried on the developing roller is reduced to room temperature 2
In an atmosphere at 5 ° C. and a relative humidity of 50%, a powder charge measuring device (for example, E-spar manufactured by Hosokawa Micron Co., Ltd.)
(Analyzer), and a method of evaluating the charge imparting property of the toner carrying surface material based on the measured amount of the reversal toner can be used. Inverted toner amount is 1
If it exceeds 5%, the amount of toner adhering to the non-image area increases, fog increases, and uncharged toner is also included in a large amount, so that good developability is not exhibited and the amount of untransferred toner increases. Therefore, a material that makes the amount of the reversal toner 15% or less is preferable.

In the present embodiment, the use of the developing roller as described above can reduce the amount of uncharged toner or reversal toner. The function deteriorates, and once collected in the developing device, it is not reused and the total amount of toner accumulated inside can be reduced.

A description will be given of the image formation in the image forming apparatus of this embodiment, and the collection and reuse of the transfer residual toner by the simultaneous development and cleaning process.

The photosensitive drum 101 and the developing roller 1 in the developing device 103 are in contact with each other, and the developing roller 1 is elastically deformed at the contact portion to form a contact nip (developing nip). The electrostatic latent image on the photosensitive drum 101 is developed by the action of the electric field. At the same time, the transfer residual toner in the previous image formation on the photosensitive drum 101 is transferred to the developing roller 1 and collected by the action of the developing electric field and the mechanical rubbing of the developing roller 1, and the photosensitive drum 101 is cleaned.

The surface potential of the photosensitive drum 101 has a ground voltage of −100 V in the electrostatic latent image portion and −680 V in the background portion, while the developing roller 1 has a ground voltage of −350 V. The voltage is applied by a developing power supply (not shown), and the photosensitive drum 101 and the developing roller 1 have an electrical potential relationship as shown in FIG.

In other words, an electric field is formed at a potential difference (development contrast) of 250 V with respect to the electrostatic latent image portion in a direction (developing direction) in which the negatively charged toner transfers from the developing roller 1 (developing direction). On the other hand, an electric field in the direction in which the toner is attracted to the developing roller 1 is formed by a potential difference of 330 V (fogging contrast). Therefore, the transfer residual toner on the photosensitive drum 101 remains in the latent image when it is in the electrostatic latent image portion, and transfers to the developing roller 1 by fogging contrast when it is in the background portion. Collected.

The width of the developing nip is 0.5 to 5 mm.
And more preferably 1 to 3.5 mm. If the developing nip width is less than 0.5 mm, it is difficult to form a uniform contact state, and the time for contacting the portion is shortened, so that it is not possible to sufficiently collect transfer residual toner. Is not desirable. On the other hand, if it exceeds 5 mm, the performance in the toner tends to deteriorate due to the stress in the nip portion, which is similarly undesirable.

In order to increase the recovery rate of transfer residual toner due to mechanical rubbing at the developing nip, the peripheral speed of the developing roller is preferably at least 160% of the peripheral speed of the photosensitive drum. If the peripheral speed of the developing roller is 160% or less, sufficient rubbing cannot be performed, and the contribution to the improvement of the collection efficiency is reduced.

In this embodiment, the photosensitive drum 101 has a peripheral speed of 150 mm / sec, and the developing roller 1 has a peripheral speed of 1 mm.
By rotating and driving at 80% of 270 mm / sec, the image forming operation was performed about 10,000 times, and various images were output. As a result, even in a pictorial image or the like, a good image excellent in uniformity of the halftone portion was maintained.

In each of the above embodiments, the case where non-magnetic toner is used as the one-component developer has been described. However, magnetic toner is used, and a magnetic field generating means is provided inside or outside the developing roller, and the magnetic force is applied. The present invention can be applied to the case where the magnetic toner is carried on the developing roller and transported. The same effect can be obtained by making the toner carrying surface of the developing roller the same.

Further, the present invention uses a one-component developer and employs a contact developing system in which the image carrier and the developer carrier are in contact with each other. Alternatively, the present invention can be applied to a case where the image carrier is an elastic belt photoreceptor or the like and the developer carrier has a rigid body, and has the same effect.

[0136]

As described above, according to the present invention,
In an image forming apparatus that forms an image by a one-component contact development method, noise in a halftone portion caused by an increase in image forming speed can be suppressed, and a good image can be obtained for a long period of time. In addition, even when the image forming apparatus performs the simultaneous development and cleaning process, it is possible to suppress noise in the halftone portion, reduce the amount of collected toner that causes functional deterioration, and obtain a good image over a long period of time.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of an image forming apparatus of the present invention.

FIG. 2 is a schematic configuration diagram illustrating a developing device installed in the image forming apparatus of FIG. 1;

FIG. 3 is an explanatory diagram showing a method of measuring a dynamic friction coefficient μ of a developing roller toner carrying surface in the present invention.

FIG. 4 shows the occurrence of image defects due to a combination of the circularity R of the toner and the dynamic friction coefficient μ of the toner carrying surface of the developing roller;
FIG. 9 is a diagram illustrating a segmentation curve that classifies non-occurrence and uses an image forming speed as a parameter.

FIG. 5 is a perspective view showing a measuring device used for measuring the charge imparting property of the forming material of the developing roller toner carrying surface to the toner in the present invention.

FIG. 6 is a diagram showing an order relationship between potentials established on a photosensitive drum and a developing roller in a simultaneous cleaning process of development in another embodiment of the present invention.

FIG. 7 is a schematic diagram showing a developing device installed in a conventional image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 developing roller 12 regulating blade 13 supply roller 101 photosensitive drum 103 developing device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yukihiro Oseki 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Manami Sekiguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon In-house F term (reference) 2H077 AA37 AC04 AC16 AD06 AD13 AD17 AD31 BA03 EA14 FA12 FA21 3J103 AA02 AA14 AA33 AA51 BA41 FA05 FA07 FA12 FA14 FA18 GA02 GA52 HA03 HA04 HA05 HA11 HA12 HA15 HA18 HA20 HA33 HA43 HA46 HA53 HA46 HA53 HA46 HA53 HA46 HA53

Claims (8)

[Claims] 1. An image carrier, comprising: a developing device, wherein the developer device carries and conveys a one-component developer toner, the developer carrier contacting the image carrier, and the developer A regulating member for regulating the toner on the carrier to a thin layer, and the toner on the image carrier is statically charged by the toner under the action of a developing electric field formed between the developer carrier and the image carrier. The electrostatic latent image is developed, and the toner image obtained by the development is transferred from the image carrier to a transfer material, and the peripheral speed V1 of the image carrier and the peripheral speed V2 of the developer carrier are 75 mm / sec. ≦ V1 <
In the image forming apparatus having the relationship of V2, the toner carrying surface of the developer carrying member is set to a dynamic friction coefficient μ with respect to SUS in the toner conveying direction by the toner carrying surface, and the circularity of the toner defined by the shape coefficient SF-2 is set. An image forming apparatus characterized in that R is formed of a low friction material that satisfies the following condition: 0.01 <μ <(15/100000) × (R-100) ² +0.16 (1) 2. The image forming apparatus according to claim 1, wherein the toner has a smooth surface shape of R ≦ 140. 3. The developer carrier according to claim 1, wherein an elastic layer and a surface layer are formed on a substrate, and the surface layer is formed of a material that satisfies the expression (1) for the coefficient of dynamic friction μ. 1 or 2 image forming apparatus. 4. The image forming apparatus according to claim 3, wherein the material is located on a side opposite to the triboelectric charging polarity of the toner in the triboelectric series. 5. The development of an electrostatic latent image on the image carrier by toner on the developer carrier under the action of the developing electric field, and the developer carrying of transfer residual toner on the image carrier. The image forming apparatus according to any one of claims 1 to 4, wherein the image forming apparatus performs a developing simultaneous cleaning process for recovering the developing body. 6. The image forming apparatus according to claim 1, wherein the toner is a non-magnetic toner. 7. The image forming apparatus according to claim 1, wherein said developer carrier is a roller-shaped developing roller. 8. The image forming apparatus according to claim 1, wherein said image carrier is a photosensitive drum.