JP2000010336A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing sticking of a wax component to the developing sleeve surface in two-component magnetic brush development using a polymerization toner containing the wax component. SOLUTION: In an image forming device having a developing device having a rotatable developer carrier 25 for oppositely carrying a two-component developer to an image carrier to develop an electrostatic latent image into a visible image by forming the electrostatic latent image on an initially electrified image carrier 3 by eliminating electric charge of the part corresponding to an image signal by an image exposing means and plural magnetic field generating means 29 fixedly arranged inside the developer carrier, the two-component developer has a nonmagnetic polemerization toner containing wax and a magnetic carrier, and the developer carrier is characterized by having the comparatively smooth recessed part and projecting part by applying blast processin on the surface by spherical particles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copier, a printer, and a recorded image display for developing a visible image by developing an electrostatic latent image formed on an image carrier by an electrophotographic method, an electrostatic recording method, or the like. The present invention relates to an image forming apparatus such as an apparatus and a facsimile.

[0002]

2. Description of the Related Art Conventionally, a dry developer as a developer is carried on the surface of a developer carrier, and this developer is transported and supplied to the vicinity of the surface of an image carrier carrying an electrostatic latent image. It is well known that an electrostatic latent image is developed and visualized while an alternating (alternating) electric field is applied between the carrier and the developer carrier.

[0003] Incidentally, since the developer carrying member generally uses a developing sleeve in many cases, it is referred to as a "developing sleeve" in the following description, and the image carrying member generally employs a photosensitive drum. Since there are many, in the following description, they will be referred to as “photosensitive drums”.

As the developing method, a magnetic brush is conventionally formed on the surface of a developing sleeve in which a magnet is disposed by using a developer (two-component developer) having, for example, a two-component composition (carrier particles and toner particles). Then, the magnetic brush is rubbed or brought close to the photosensitive drum facing the photosensitive drum while maintaining a small developing gap, and an alternating electric field is continuously applied between the developing sleeve and the photosensitive drum (between SD). The development is performed by repeatedly performing the dislocation and reverse dislocation of the toner particles from the developing sleeve side to the photosensitive drum side by performing
A so-called magnetic brush developing method is known (see, for example, JP-A-55-32060 and JP-A-59-165082). A non-contact type alternating electric field development method using a two-component developer for simple color development or multiple development is also known (for example, JP-A-56-14268, JP-A-58-68051). No., JP-A-56-14
4452, JP-A-59-181362 and JP-A-60-176069).

[0005] In recent years, for the purpose of further improving transferability and image quality, toners which are produced by a polymerization method and have a substantially spherical shape have been developed. Due to the shape factor, this toner has good releasability from the photosensitive drum, and as a result, high transfer efficiency can be obtained, and particularly, high-density large-area images have high quality. On the other hand, when two-component development is performed using this toner, the friction coefficient μ between the sleeve and the developer becomes low because the shape of the toner is close to a spherical shape. When the surface of the developing sleeve is subjected to a surface treatment (2 μm ≦ Rz ≦ 3 μm) by sandblasting, the transportability of the developer is insufficient, so that the weight per unit area (hereinafter referred to as M / S) is difficult to stably coat on the developing sleeve.

[0006] The amount of M / S on the developing sleeve is closely related to image quality, and it is important to stably obtain a desired M / S for a long period of time in order to maintain high image quality for a long time. This problem is caused by increasing the surface roughness on the developing sleeve, specifically, (4 μm ≦ Rz ≦ 20 μm)
By doing so, it becomes possible to coat a desired M / S on the developing sleeve in a developer using the above-mentioned polymerized toner, which had insufficient transportability with the conventional developing sleeve.

[0007]

As described above, in the two-component development using the polymerized toner, the transportability of the developer is stabilized by increasing the surface roughness of the developing sleeve as compared with the conventional one. However, in the surface treatment of the developing sleeve by sand blasting or the like, since the shape of the particles required for the treatment is irregular with projections and the like, the peak-to-peak average interval (Sm) is narrow. Problems arise.

In order to simplify the configuration of the apparatus by oilless fixing, when a wax component or the like is contained in the toner itself, pressure is applied to the toner to cause the wax component to exude and adhere to the developing sleeve. The present inventors have found that by rubbing the developing sleeve while the additives and the fine powder toner are held by the magnetic brush, the developing sleeve gradually contaminates the developing sleeve thermally and electrostatically and contaminates the developing sleeve. It became clear by examination of. As a result, the surface roughness of the developing sleeve is substantially reduced, reducing the conveying force,
A phenomenon occurs in which the M / S gradually decreases. Also, when a magnetic carrier having a large amount of magnetization is used,
The phenomenon was more pronounced. This is because the magnetic adhesion between the developing sleeve and the magnetic carrier increases,
This is probably because the toner adhering to the carrier is more pressed against the developing sleeve, so that the wax component and the like more adhere to the developing sleeve and contaminate the developing sleeve.

Accordingly, an object of the present invention is to provide an image forming apparatus which prevents the attachment of a wax component or the like on the surface of the developing sleeve in a conventional two-component magnetic brush development using a polymerized toner containing a wax component or the like. That is.

[0010]

The above object is achieved by an image forming apparatus according to the present invention.

In summary, according to the present invention, an electrostatic latent image is formed on an initially charged image bearing member by erasing a charge corresponding to an image signal by an image exposing means. In order to develop an image into a visible image, a rotatable developer carrier that carries and transports a two-component developer in opposition to the image carrier, and a plurality of developer carriers fixedly provided inside the developer carrier. In the image forming apparatus provided with a developing device having a magnetic field generating means, the two-component developer has a non-magnetic polymerized toner containing a wax and a magnetic carrier, and the developer carrier has spherical particles on the surface. The image forming apparatus is characterized in that it is subjected to blast processing and has relatively smooth concave and convex portions.

The average particle diameter of the non-magnetic polymerized toner is 4
When the thickness is from 12 μm to 12 μm, the surface shape of the developer carrier satisfies the following condition.

4 μm ≦ Rz ≦ 20 μm 30 μm ≦ Sm ≦ 80 μm

The shape factor SF of the non-magnetic polymerized toner is
-1 is in the range of 100 to 140, and SF-2 is in the range of 100 to 120.

The magnetic carrier has a magnetization in a magnetic field of 1 KOe within a range of ^{30 to} 200 emu / cm ³ and a number average particle size of the carrier of 10 to 6 emu / cm ^3.
It is characterized by being within the range of 0 μm.

Further, the above-mentioned developing device is characterized in that the two carriers move in directions opposite to each other at a portion where the image carrier and the developer carrier face each other.

[0017]

FIG. 2 is a schematic structural view of an electrophotographic full-color image forming apparatus to which the present invention can be applied.

The image forming apparatus includes a photosensitive drum 3 rotating in the direction of an arrow, and a rotary developing device 1 including a charger 4 and developing units 1M, 1C, 1Y, and 1BK around the photosensitive drum 3.
It comprises a transfer discharger, a cleaning means 12, and an image forming means such as a laser beam scanner LS arranged above the photosensitive drum in the figure. Each developing device supplies a two-component developer containing toner particles and carrier particles to the photosensitive drum. The developer of the developing device 1M contains magenta toner, the developer of the developing device 1C contains cyan toner, the developer of the developing device 1Y contains yellow toner, and the developer of the developing device 1BK contains black toner. A document reading device having a photoelectric conversion element such as a CCD outputs image signals corresponding to magenta image information, cyan image information, yellow image information, and monochrome image information of the document. The semiconductor laser incorporated in the laser beam scanner is controlled according to these image signals and emits a laser beam L. The output signal from the electronic computer can also be printed out.

In the sequence of the entire full-color image forming apparatus, first, the photosensitive drum is uniformly charged by the charger. Next, scanning exposure is performed with the laser light L modulated by the magenta image signal, an electrostatic latent image is formed on the photosensitive drum 3, and the electrostatic latent image is formed by the magenta developing device 1M fixed at the developing position. Reversal development is performed.

On the other hand, the transfer material such as paper taken out of the paper feed cassette C and advanced through the paper feed guide 5a, the paper feed roller 6, and the paper feed guide 5b is transferred to the gripper 7 of the transfer drum 9.
, And is electrostatically wound around the transfer drum 9 by the contact roller 8 and its opposite pole. Transfer drum 9
Rotates in the direction indicated by the arrow in synchronization with the photosensitive drum 3, and the magenta image developed by the magenta developing device 1M is
In the transfer section, the image is transferred to a transfer material by a transfer charger 10. The transfer drum 9 continues to rotate as it is, and prepares for transfer of an image of the next color (cyan in FIG. 2).

On the other hand, the photosensitive drum 3 is discharged by the charger 11 and cleaned by the cleaning means 12, charged again by the charger, and exposed by the laser beam L modulated by the next cyan image signal. As a result, an electrostatic latent image is formed. During this time, the developing device 1 rotates, and the cyan developing device 1C is fixed at a predetermined developing position, performs reversal development of the electrostatic latent image corresponding to cyan, and forms a cyan image.

Subsequently, the above steps are performed for the yellow image signal and the black and white image signal, respectively, and when the transfer of the image (toner image) for four colors is completed, the charge of the transfer material is removed by the chargers 13 and 14. Then, the gripper 7 is released, separated from the transfer drum by the separation claw 15, and sent to the fixing device (heat roller fixing device) 17 by the transport belt 16. The fixing device 17 fixes the four color images overlapping on the transfer material. Thus, a series of full-color image forming sequences is completed, and a required full-color image is formed.

Next, the developing device will be described with reference to FIG. Since each developing device has the same configuration, only the developing device 1M will be described.

The developing device 1M includes a developer container 18, and the inside thereof is partitioned by a partition wall 19 into a developing chamber R1 and a stirring chamber R2, and a toner storage chamber R3 is provided above the stirring chamber R2.
The supply toner 20 is stored therein. From the replenishing port 21 at the lower part of the toner storage chamber R3, an amount of toner corresponding to the toner consumed in the development is dropped and supplied into the stirring chamber R2. On the other hand, the developer 22 in which the toner particles and the magnetic carrier are mixed is accommodated in the developing chamber R1 and the stirring chamber R2. Details of the toner particles and the magnetic carrier used in the present invention will be described later.

A transport screw 23 is accommodated in the developing chamber R1, and transports the developer along the longitudinal direction of the developing sleeve 25 by rotational driving. The direction in which the developer is conveyed by the screw 24 is the opposite direction to that by the screw 23.

The partition wall 19 has openings on the near side and the back side. The developer conveyed by the screw 23 is transferred to the screen 24 from one of the openings, and
The developer conveyed in 4 is delivered to the screw 23 from the other one of the openings.

An opening is provided in a portion of the developer container 18 adjacent to the photosensitive drum 3, and the opening is made of a material such as aluminum or non-magnetic stainless steel, and has a non-magnetic developing material having moderate irregularities on its surface. A sleeve 25 is provided.

The developing sleeve 25 rotates at a peripheral speed Vb in the direction of the arrow b (the direction opposite to the photoconductor rotating direction), and is regulated to an appropriate developer layer thickness by a layer thickness regulating blade 28 at the lower end of the opening of the developing container. Thereafter, the developer is carried and transported to the developing area 26. The rotation direction of the developing sleeve is not limited to the above-described direction, and may be the same as the photoconductor rotation direction. The magnetic brush of the developer carried on the developing sleeve 25 contacts the photoreceptor 3 rotating at the peripheral speed Va in the direction of arrow a in the developing area 26, and the electrostatic latent image is developed in the developing area 26. The peripheral speed Vb of the sleeve 25 is a photosensitive drum peripheral speed ratio of 130 to 2
00% is desirable, and 150-180% is even better.
When the ratio is below the above range, a sufficient image density cannot be obtained, and when the ratio exceeds the above range, the developer is scattered. In the developing sleeve 25, a roller-shaped magnet 29 is fixedly arranged. The magnet 29 has a development magnetic pole S1 facing the development area 26. The developing magnetic pole S1 forms a magnetic brush of a developer by a developing magnetic field formed in the developing area 26, and the magnetic brush contacts the photosensitive drum 3 to develop an electrostatic latent image. At this time, the toner adhering to the magnetic brush and the toner adhering to the surface of the developing sleeve are transferred to the image area of the electrostatic latent image and developed. In this embodiment, the magnet has N1, N2, N3, and S2 poles in addition to the developing magnetic pole S1.

With this configuration, the developer applied on the N3 pole and the S2 pole by the rotation of the developing sleeve 25 passes through the layer thickness regulating blade 28 and the developing magnetic pole S1 as in the related art.
Then, the developer rising in the magnetic field develops the electrostatic latent image on the photosensitive drum 3. Thereafter, the developer on the developing sleeve 25 falls into the stirring chamber R1 due to the repulsive magnetic field between the N2 pole and the N3 pole. The developer dropped into the stirring chamber R1 is stirred and transported by the screws 23 and 24.

Next, the developing sleeve used in the present invention will be described in detail.

As described in the conventional example, it is considered that the phenomenon of M / S reduction on the developing sleeve is caused by contamination of the developing sleeve surface by a wax component or the like of the toner. Therefore, in order to prevent the developing sleeve from being contaminated without deteriorating the transportability of the developer, the present inventors performed a blasting process using glass beads for the surface treatment of the developing sleeve. Compared to the process by sandblasting, by increasing the peak-to-peak interval (Sm) as shown in FIG. 3 without changing the value of Rz which greatly affects the conveying force,
The unevenness of the surface becomes smooth, and the force of pressing the toner against the developing sleeve at the uneven portion or the like becomes small. as a result,
It has become possible to prevent wax and external additives from adhering to the developing sleeve.

In particular, the average particle size of the magnetic carrier is from 10 to 60.
In a two-component developer in which the average particle diameter of the non-magnetic toner is 4 μm to 12 μm, the surface shape of the developing sleeve preferably satisfies the above value: 4 μm ≦ Rz ≦ 20 μm 30 μm ≦ Sm ≦ 80 μm

When Rz is less than 4 μm, the developer cannot be stably coated on the developing sleeve due to insufficient transportability of the developer. Conversely, when Rz is more than 20 μm, the transportability is improved, but the developing property is improved. It is not preferable because the rubbing force applied to the developer becomes too strong, and the deterioration of the developer during the durability increases.

When Sm is less than 30 μm, sleeve contamination due to wax and external additives contained in the toner becomes a problem. Conversely, when Sm is more than 80 μm, the transportability is reduced due to the decrease in the number of irregularities and the developing sleeve The upper developer does not stably coat.

The surface treatment method of the sleeve is not limited to the method shown in the above embodiment, but may be any method using particles having few projections.

The method for measuring the surface shape of the developing sleeve will be described below.

In the present invention, Rz and Sm are JIS-
It is a value that defines the ten-point average roughness and the average interval of unevenness described in B0601 and ISO468, and is obtained by the following equation. Rz = [(R1 + R3 + R5 + R7 + R9)-(R2 +
R4 + R6 + R8 + R10)] / 5 Ri: Peak value of unevenness Sm = (1 / n) Σ (i = n) (Smi) Smi: Interval of unevenness The contact type surface roughness measuring instrument SE-3300 (Kosaka Laboratory Co., Ltd.) Manufactured by Toshiba Corporation.

Next, the carrier used in the present invention will be described. High image quality can be achieved in a two-component developing system which is a combination of a low-magnetization carrier and a spherical polymerization toner used in the present invention.

According to experiments by the present inventors, the SD gap was 300 to 1000 μm, and the M / S was 20 to 50 mg /
cm ² and a T / D ratio in the range of 5 to 12%, the carrier has a magnetization of 200 emu / cm ³ or less, preferably 14 emu / cm ³ or less.
If it is 0 emu / cm ³ or less, the force at which the developer is magnetically attracted to the developing sleeve is considerably smaller than that of Cu-Zn ferrite (about 28 emu / cm ³ ) which is generally used. . As a result, the magnetic adhesion between the developing sleeve and the carrier is reduced, and the force with which the toner sandwiched therebetween is pressed against the developing sleeve is reduced, so that even in a system using a polymerized toner containing a wax component, It was possible to prevent contamination due to adhesion of wax, external additives, and the like on the developing sleeve.

[0040] is in the range of magnetization of the carrier, in view of the high releasability and carrier adhesion polymerized toner containing wax, 30~200emu / cm ^3, preferably 80~140emu / cm ³ is correct is there. 30e
If the value is less than mu / cm ³ , not only the carrier adhesion increases, but also the developer cannot be applied and conveyed magnetically on the developing sleeve. . Also, 200 em
If it exceeds u / cm ³ , the developing sleeve becomes more contaminated in a system using a polymerized toner containing a wax.

By optimizing the range of the particle size of the carrier and the range of the specific resistance simultaneously with the above-mentioned magnetization amount, the phenomenon of contamination of the developing sleeve can be solved while further preventing carrier adhesion and image deterioration. In other words, by setting the number average particle size of the carrier in the range of 10 to 60 μm, it is possible to prevent the carrier having a small particle size from adhering to the photoreceptor and to prevent the large-sized carrier from easily observing the unevenness of the carrier, and the resistivity of the carrier. 10
^By setting the thickness within the range of ¹⁰ to 10 ¹⁴ Ωcm, even if the carrier has a low magnetization, it is possible to prevent carrier adhesion due to charge injection and prevent image deterioration due to charge-up of the carrier.

By using the above-described carrier having a low magnetization amount, it is possible to achieve high image quality in addition to unevenness. The reason is that the magnetic interaction between the adjacent magnetic brushes is small due to the low magnetization amount, and as a result, the spikes of the magnetic brush are dense and short, so that a high-resolution image can be provided. .

In the present invention, the low-magnetization amount carrier is produced by polymerizing a resin magnetic carrier comprising a binder resin, a magnetic metal oxide and a non-magnetic metal oxide. For example, the amount of magnetization may be controlled.

The method for measuring the amount of magnetization, particle size, and specific resistance will be described below.

First, regarding the amount of magnetization, the magnetic properties of the carrier were measured using an oscillating magnetic field type magnetic property automatic recording device manufactured by Riken Denshi Co., Ltd. in a cylindrical shape in an external magnetic field of 1 KOe (kilo Oersted). The amount of magnetization (emu / emu /
cm ³ ) was calculated.

The particle size was determined by taking a photograph of a carrier particle randomly extracted by 300 using a scanning electron microscope and using a Luzex3 image processing / analysis device manufactured by Nicole Co., Ltd. to obtain the carrier particle size in terms of the Feret diameter in the horizontal direction. Was calculated.

For the specific resistance, a measuring device shown in FIG. 4 was used.
The electrodes 30 and 3 are connected to the cell E so as to be in contact with the carrier 33.
1, a voltage 32 is applied between the electrodes, and the current flowing at that time is measured to determine the specific resistance. The measurement conditions of the specific resistance used in the present invention are as follows: the contact area S between the charged carrier and the electrode is about 2.3 cm ² , the thickness d is about 2 mm, the load of the upper electrode 31 is 180 g, and the measured electric field strength is 5 × 10 ⁴ V /.
m.

Next, the toner particles used in the present invention will be described.

The toner particles of the present invention use a polymerized toner containing a wax component in order to achieve high transfer efficiency and achieve oilless fixing as described in the prior art. In this example, spherical toner particles were obtained by suspending and polymerizing a monomer composition obtained by adding a colorant and a charge control agent to a monomer of a polymerization method in an aqueous medium. The production method is not limited to the above-mentioned method, and may be produced by an emulsion polymerization method or the like, or may contain other additives.

The spherical toner has a shape factor S
It is preferable that F-1 is 100 to 140 and SF-2 is 100 to 120 in order to maintain high transfer efficiency. The SF-1 and SF-2 are Hitachi FE-SEM
Using (S-800), 100 toners were randomly sampled, and the image information was introduced into an image analyzer (Luzex3) manufactured by Nicole via an interface, analyzed, and calculated by the following equation. The values were defined as shape factors SF-1 and SF-2 in the present invention.

[0051]

(Equation 1) (AREA: toner projection area, MXLNG: absolute maximum length, PERI: circumference)

The above SF-1 indicates a degree of sphericity, and 10
When the value is 0 and the value is a true sphere, the value gradually increases from a sphere to an irregular shape. SF-2 indicates the degree of unevenness, and when it is larger, the unevenness of the surface area becomes remarkable.

Next, the counter developing method used in the present invention will be described.

As described above, contamination of the developing sleeve in the two-component developing system of the polymerized toner containing the wax component can be prevented by using the developing sleeve and the low magnetization amount carrier whose surface is treated with the glass beads. However, according to further studies by the present inventors, the problem of developing sleeve contamination is that a so-called counter developing method is adopted in which the moving direction of the developing sleeve and the photosensitive drum is opposite at the opposing portion of the developing sleeve and the photosensitive drum. It was found that it would be further improved. This is the same as the conventionally used forward developing method in which the moving direction of the developing sleeve and the photosensitive drum is the same at the opposing portion of the developing sleeve and the photosensitive drum. In the case where the developing device has an agent pool required for this purpose, the developer in the pool is pressed against the developing sleeve by a magnetic restraining force. Therefore, it is considered that in the counter developing method without the agent pool, the force of pressing the developer against the developing sleeve is reduced. Further, in the forward developing system, the developer regulated in the developer regulating unit is compressed by its own weight and the developer conveyed later and pressed against the developing sleeve, whereas in the counter developing system, the regulated developer is regulated. It is considered that since the developer naturally circulates to the lower portion, the compression is reduced and the force of pressing the developer against the developing sleeve is reduced, so that the contamination of the developing sleeve is improved.

In the contents of the embodiment described above, M / S on the developing sleeve was performed under the conditions of the following Examples 1 to 3 and Specific Soft Example 1.
Changes were compared.

(Example 1) The magnetic carrier, toner, developing sleeve rotation direction and the like used in Example 1 will be described. Developer: polymerized toner + resin magnetic carrier; T / D ratio =
8% Carrier: Resin magnetic carrier produced by polymerization method 1 Magnetization amount in KOe magnetic field; 280 emu / cm ³ Number average particle diameter; 40 μm Specific resistance; 10 ¹³ Ωcm Toner: Polymerized toner produced by suspension polymerization method Shape factor SF-1; 115, SF-2; 110 Weight average particle diameter; 6 μm Specific gravity; 1.05 g / cm ³ Average charge per unit mass; 25 μC / g Weight of developer on sleeve per unit area: 25 mg /
cm ² Sleeve surface roughness: Developing sleeve blasted with glass beads Rz; 4.3 μm, Sm; 50 μm Sleeve rotating direction: forward developing method

(Comparative Example 1) The contamination of the developing sleeve when the developing sleeve subjected to the following surface treatment was used was compared with that of Example 1. This comparative example is characterized by a difference in the surface treatment of the developing sleeve. Sleeve surface roughness: Sandblasted developing sleeve Rz: 5.3 μm, Sm: 21 μm Other conditions are the same as in Example 1.

(Example 2) The contamination of the developing sleeve when the following magnetic carrier was used was compared with that of Example 1 above. This embodiment is characterized by a difference in the amount of magnetization of the magnetic carrier. Ferrite carrier: Magnetization in a KOe magnetic field; 135
emu / cm ³ Other conditions are the same as in Example 1.

Example 3 The contamination of the developing sleeve when the counter developing method was used in Example 1 was compared with Example 1. This embodiment is characterized by a difference in the developing sleeve rotation direction.

The other conditions are the same as in the first embodiment.

In evaluating the degree of contamination of the developing sleeve with the above configuration, a rotatable developing sleeve that carries and transports a two-component developer composed of a non-magnetic toner and a magnetic carrier produced by a polymerization method, In a developing device having a developing unit in which a plurality of magnetic field generators fixedly provided inside a developing sleeve are arranged, when the developing sleeve is continuously rotated for 5 hours, M /
The extent to which the value of S decreases from the initial value was measured in Examples 1 to 3 and Comparative Example 1, and summarized in Table 1.
In the table, ◎ indicates that the reduction rate of the value was less than 10%, の indicates that the reduction rate was less than 20%, and × indicates that the reduction rate was smaller than the initial value of M / S on the developer sleeve. 20% or more.

[0062]

[Table 1]

In comparison with Example 1 and Comparative Example 1, the reduction in M / S due to contamination of the developing sleeve was suppressed in Example 1 in which the developing sleeve was blasted with spherical particles. The effect of the surface treatment of the developing sleeve is recognized. Further, in Example 2 using low-magnetization carriers, the reduction in M / S due to contamination of the developing sleeve was suppressed more than in Example 1, and the effect of low-magnetization carriers was observed. Further, in Example 3 using the counter developing method, the reduction in M / S due to contamination of the developing sleeve was suppressed more than in Example 1, and the effect of the counter developing method was recognized.

[0064]

As is apparent from the above description, according to the present invention in which the surface of the developing sleeve is improved, contamination of the developing sleeve due to fusion of wax and external additives is reduced, and the M / M on the developing sleeve is reduced. S can be prevented from lowering.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a developing device of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an electrophotographic color image forming apparatus to which the present invention can be applied.

FIGS. 3A and 3B are schematic diagrams illustrating a surface shape of a developer carrier according to an embodiment of the present invention and a surface shape of a developer carrier according to a comparative example, respectively.

FIG. 4 is an explanatory diagram of a specific resistance measuring device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 developing device 3 photoreceptor drum (image carrier) 17 fixing device 18 developer container 22 developer 23, 24 screw 25 developing sleeve (developer carrier) 26 developing area 28 layer thickness regulating blade 29 magnet

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masaru Hibino 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masanori Shida 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon F term in reference (reference) 2H005 AA06 AA15 AB06 BA03 CA14 EA02 EA05 FA02 2H031 AC10 AC14 AC17 BA05 BA09 2H077 AD02 AE04 AE06 EA03 FA01

Claims (5)

[Claims] 1. An electrostatic latent image is formed on an initially charged image bearing member by erasing a charge corresponding to an image signal by an image exposing means, and the electrostatic latent image is developed into a visible image. A rotatable developer carrier that carries and conveys the two-component developer in opposition to the image carrier, and a plurality of magnetic field generating means fixedly provided inside the developer carrier. In the image forming apparatus provided with a developing device, the two-component developer has a non-magnetic polymerized toner containing a wax and a magnetic carrier, and the surface of the developer carrier is blasted by spherical particles. An image forming apparatus having relatively smooth concave portions and convex portions. 2. The non-magnetic polymer toner used in the two-component developer has a weight average particle diameter of 4 to 12 μm, and the surface shape of the developer carrier satisfies the following conditions. Item 2. The image forming apparatus according to Item 1. 4 μm ≦ Rz ≦ 20 μm 30 μm ≦ Sm ≦ 80 μm 3. A shape factor SF- of the non-magnetic polymerized toner.
The image forming apparatus according to claim 1, wherein 1 is in a range of 100 to 140, and SF-2 is in a range of 100 to 120. 4. The magnetic carrier according to claim 1, wherein said magnetic carrier has a magnetization in a magnetic field of 1 KOe within a range of ^{30 to} 200 emu / cm ³ , and has a number average particle size of 10 to 60 emu / cm ^3.
The image forming apparatus according to claim 1, wherein the distance is in a range of μm. 5. The developing device according to claim 1, wherein the two carriers move in directions opposite to each other at a portion where the image carrier and the developer carrier are opposed to each other. Image forming apparatus.