JP2002149031A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide stable cleaning performance by preventing the damage of a cleaning blade or occurrence of a cleaning defect when cleaning an almost spherical toner. SOLUTION: A toner image formed on the surface of a photoreceptor drum 3a is transferred on a recording member by a transfer charger and a residual toner left on the surface of the photoreceptor drum 3a after transfer is removed by a cleaning blade 43 abutted on the surface of the photoreceptor drum 3a. The cleaning blade 43 is formed from a urethane rubber and is abutted in a counter direction in respect of a moving direction (the direction of an arrow) of the surface of the photoreceptor drum 3a. A plurality of layers is provided on the surface of the photoreceptor drum 3a, a surface layer among these layers contains a fluororesin and a content F (wt.%) is set to be 10<=F<=50. Besides, surface roughness Rz (μm) of the photoreceptor drum 3a is set to be Rz<5.0. Further, a dynamic friction coefficient μ between the surface of the photoreceptor drum 3a and the cleaning blade 43 is set to be 0.5<=μ<=2.5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, and the like.

[0002]

2. Description of the Related Art Recently, an electrophotographic multifunction machine having all output terminals such as a copying machine, a printer, and a facsimile has been widely used as an output terminal for a network. One of the major problems of such an electrophotographic multifunction machine is an increase in the duty cycle of the apparatus main body. The duty cycle refers to a limit number of images for which the apparatus main body can continue to operate normally without maintenance by a service person. The limit number is largely determined by the life of the photosensitive drum.

[0003] From the viewpoint of ecology, elimination of wastes, that is, reduction of consumables, extension of life of consumables, and improvement of reliability have become major issues.

[0004] Further, with respect to the apparatus main body, digitization has progressed from the conventional analog apparatus, and there is a problem that the cost of the digitized apparatus main body is made equal to or less than that of the analog apparatus.

Further, in the past, black-and-white machines have been the mainstream in copying machines and printers, but full-color machines have been rapidly increasing in offices and the like. In addition to the apparatus itself, there is a demand for a full-color machine having a running cost similar to that of a monochrome machine. For that, TCO
There is a need for a technology that can dramatically reduce (the overall required cost as viewed from the user).

Under these circumstances, in recent years, a plurality of electrophotographic photosensitive members (photosensitive members) as image bearing members and a transfer belt (recording material bearing member) for carrying and transporting a recording material have been provided. A color image forming apparatus (e.g., 4) in which a transferable toner image of a different color (hereinafter simply referred to as a “toner image”) formed on each photoconductor is sequentially superimposed and transferred onto the recording material thus obtained. A continuous tandem type color image forming apparatus) is widely used.

In an image forming apparatus in which the process of transferring a toner image formed on the surface of a photoreceptor onto a recording material (mainly paper) is repeated, the toner remaining on the surface of the photoreceptor without being transferred to the recording material during transfer is used. It is essential to sufficiently remove the residual toner) each time.

For this reason, many cleaning means have been proposed in the past. Among them, those which scrape off residual toner by a cleaning blade made of an elastic material such as urethane rubber have a simple and compact structure. It is widely used because of its advantages such as low cost and excellent toner removal function. As a rubber material for the cleaning blade, urethane rubber which is high in hardness and rich in elasticity and is excellent in friction resistance, mechanical strength, oil resistance, and ozone resistance is generally used.

[0009]

However, in the above-described image forming apparatus, the following first to fourth problems have occurred.

First, the frictional force between the photosensitive member and the residue on the photosensitive member due to the cleaning blade increases due to durability. This has been confirmed by experiments. Due to the filming film formed by the durability, the degree of adhesion and affinity between the cleaning blade and the surface of the photoconductor and between the residue and the surface of the photoconductor are increased, thereby increasing the frictional force. It was also found that there was a difference in the increase of the frictional force after the endurance depending on the shape of the photoreceptor surface by the initial polishing.

It is considered that the increase in the frictional force is due to an increase in the shear stress of the cleaning blade, the shear stress between the toners, and the shear stress near the photosensitive member surface. As a result, chipping of the cleaning blade (local edge chipping), toner fusion due to an increase in heat generation due to an increase in permanent set shear stress, and an increase in fatigue wear due to an increase in the internal stress of the photoconductor may be caused. Conceivable. Excessive reduction of the frictional force results in loss of adhesion between the edge of the cleaning blade and the surface of the photoreceptor, resulting in a loss of the original effect of abrading the surface of the photoreceptor.
That is, when continuous image formation is performed in a system having an excessively low frictional force, a filming film is easily formed, and conversely, the frictional force may be increased as described above.

Secondly, in recent years, as described above, since it is widely used not only as a function of a copying machine but also as a printer, the number of images formed at one time increases and a residue is left on the surface of a photoreceptor. It becomes easy to adhere. Advances in applications such as a feeder function and a sorter function have advanced, and it has become possible to perform continuous operation of 4000 or more jobs (number of images formed) at one time. For example, in the case of 50 sheets / min A4 machine,
Even if a simple calculation is made, a continuous image forming operation for 80 minutes or more is performed. Under such circumstances, it is considered that the ambient temperature near the transfer belt has reached nearly 50 ° C., and the temperature at the contact portion (nip portion) between the cleaning blade and the photoconductor surface has reached a higher temperature. . As a result, the frequency of sticking or adhesion of the residue on the surface of the photoreceptor has increased.

Third, as the particle size of the toner becomes smaller, development with excellent dot reproducibility and resolution can be performed, and the sharpness and the image quality of the toner image are improved. , The adhesion of the toner to the surface of the photoconductor per unit weight increases, and the cleaning performance of the surface of the photoconductor deteriorates.
As the particle size of the toner decreases, the fluidity of the toner deteriorates, so that a larger amount of additives is required. However, this causes wear and chipping of the cleaning blade as described above, There is a problem that streak scratches and the like occur.

Fourth, in recent years, polymerized toners have been widely used for the purpose of improving transfer efficiency and eliminating the need to apply a release agent to fixing means. However, toners produced by the polymerization method generally have high sphericity. If the sphericity increases, when a conventional counter blade system is used, toner will pass through more at the same contact pressure as in the related art, and it is necessary to further increase the contact pressure. For this reason, a local shearing force is applied to the cleaning blade, causing edge chipping.

In order to prevent the above-described first to fourth problems, a method of applying a lubricant to the edge of the cleaning blade in advance, thereby reducing the frictional force between the photosensitive member and the cleaning blade. Has been performed conventionally.

For example, when spherical particles are used as a lubricant, the lubricating properties of the particles themselves are very high, and they are excellent in the effect as a lubricant. However, they have the property of easily slipping through the edge of the cleaning blade. In some cases, the lubrication effect is lost due to the edge portion falling off from the edge portion due to minute vibration. As a countermeasure, attempts were made to increase the amount of spherical particles applied.
As a result, the amount of peeling increases, which causes a problem that the peeled lubricant is present on the photoreceptor, hinders exposure, and causes image defects.

If irregular particles are used as a lubricant, the particles can be prevented from slipping through the edge of the cleaning blade, but foreign matters such as toner collect near the edge because the particles themselves have poor lubricating ability. At the initial stage until a sufficient lubrication effect is obtained, there is a problem that so-called chatter (abnormal vibration) easily occurs between the photoreceptor surface and the cleaning blade.

As means for solving these problems, there are provided both an irregular lubricant-applied area mainly composed of irregular particles and a spherical lubricant-applied area mainly composed of spherical particles, and both ends of an edge portion of the cleaning blade are provided. For example, a method of setting an amorphous lubricant application area has been devised.

As described above, a stable state of the cleaning blade can be obtained to some extent by devising the method of applying the lubricant, but it has been difficult to obtain stable performance over a long period of time.

On the other hand, as another conventional technique aimed at stabilizing the cleaning, there are those proposed in Japanese Patent Application Laid-Open Nos. 4-33587 and 11-218953.

The former Japanese Patent Application Laid-Open No. 4-33587 discloses an image bearing member (photoreceptor) in which a urethane rubber cleaning blade contains a fluorine compound or a silicone compound.
Coefficient of dynamic friction between the cleaning blade and the cleaning blade is 0.2-1.
A configuration for setting the range to 2 is described.

Japanese Patent Application Laid-Open No. H11-218953 discloses that the outermost layer of a photoreceptor contains fluororesin particles in order to improve the cleaning performance of spherical toner, and the friction between the photoreceptor surface and a urethane blade is increased. A configuration in which the coefficient is less than 1.0 is described.

However, in any of the above structures, the usable range of the friction coefficient (range) is as narrow as about 1.0, so that the photosensitive member and the cleaning blade must be fitted together to keep the friction coefficient within this range. However, there is a problem that the cost is high and the cleaning performance tends to be unstable.

The present invention has been made in view of the above circumstances, and when cleaning a substantially spherical toner, the cleaning blade is prevented from being damaged or a cleaning defect is prevented from occurring, and stable cleaning performance is obtained. It is an object to provide an image forming apparatus.

[0025]

The invention according to claim 1 is
A first image carrier for carrying a toner image formed by substantially spherical toner on the surface, a transfer unit for transferring the toner image on the surface of the first image carrier to a second image carrier, 1
A cleaning member that abuts on the surface of the image carrier and removes toner remaining on the surface of the first image carrier after the transfer operation by the transfer unit.
The first image bearing member contains a fluororesin on its surface, and the content F (% by weight) of the fluororesin is 10 ≦
F ≦ 50, the surface roughness Rz (μm) of the surface of the first image carrier is Rz <5.0, and the dynamic friction between the surface of the first image carrier and the cleaning member The coefficient μ is 0.5 ≦ μ ≦ 2.5.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the first image carrier has a plurality of layers on a front surface side, and a surface layer of the plurality of layers is provided on a surface layer. It is characterized by containing a fluororesin.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the first image bearing member comprises:
The surface roughness Rz is in the range of Rz <5.0,
The surface is polished.

The invention according to claim 4 is the invention according to claims 1 to 3
The image forming apparatus according to any one of the above, wherein the toner has a weight average particle diameter R (μm) in a range of 6 ≦ R ≦ 10.

According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the toner has a shape factor SF1.
Is within the range of 100 ≦ SF1 ≦ 140, and the shape factor S
F2 is within the range of 100 ≦ SF2 ≦ 120.

The invention according to claim 6 is the invention according to claims 1 to 5
In the image forming apparatus according to any one of the above, the cleaning member may have a linear pressure A (N / cm) of 200 × 10 ⁻³ <A <60 when contacting the first image carrier surface.
It is within a range of 0 × 10 ⁻³ .

The invention according to claim 7 is the invention according to claims 1 to 6
5. The image forming apparatus according to claim 1, wherein the cleaning member is a cleaning blade having elasticity.

According to an eighth aspect of the present invention, in the image forming apparatus according to the seventh aspect, the cleaning blade comprises:
The first image carrier is abutted in a counter direction with respect to a moving direction of the surface of the first image carrier.

According to a ninth aspect of the present invention, in the image forming apparatus according to the eighth aspect, the cleaning blade comprises:
It is formed of urethane rubber.

According to a tenth aspect, in the image forming apparatus according to any one of the first to ninth aspects, the toner is a non-magnetic toner.

According to an eleventh aspect of the present invention, in the image forming apparatus according to any one of the first to tenth aspects, the toner is manufactured by a polymerization method.

According to a twelfth aspect of the invention, in the image forming apparatus according to any one of the first to eleventh aspects, the second
And a plurality of first image carriers provided along a moving direction of the recording material carrier, and the plurality of first image carriers are provided. The toner images formed on the body surface are sequentially transferred onto a second image carrier carried and conveyed by the carrier.

According to a thirteenth aspect of the present invention, in the image forming apparatus of the twelfth aspect, the toner images formed on the plurality of first image carriers are toner images of different colors. It is characterized by.

According to a fourteenth aspect of the present invention, in the image forming apparatus according to any one of the first to thirteenth aspects, the first image forming apparatus comprises:
When the image bearing member is a rotating member having a radius of γ (cm), the dynamic friction coefficient μ is such that the cleaning member contacts the surface of the first image bearing member with respect to the rotational torque of the first image bearing member. When the rotation torque is not set to T1 (kgf ·
cm), and the rotational torque during the contact is T2
(Kgf · cm) and the contact load at the time of contact is F
(Kgf), μ = (T2−T1) / (F ·
γ).

[0039]

Embodiments of the present invention will be described below with reference to the drawings.

<Embodiment 1> FIG. 1 shows an example of an image forming apparatus according to the present invention. The image forming apparatus shown in FIG. 1 is an electrophotographic four-color full-color image forming apparatus, and FIG. 1 is a longitudinal sectional view showing a schematic configuration thereof.

The image forming apparatus shown in FIG. 1 includes a process unit such as an image carrier in an image forming apparatus main body 1.
Image forming stations (image forming units) Pa, Pb,
Pc and Pd are provided. Below these image forming stations Pa, Pb, Pc, Pd, rollers 13, 1
An endless transfer belt (recording material carrier) 130 stretched between 4 and 15 is provided. The transfer belt 130 is
It is rotationally driven in the direction of arrow A by a drive motor (not shown). Below the transfer belt 130, a paper feed cassette 10 in which a recording material (a second image carrier) P such as paper is stored is arranged. Paper is fed in order from the one. The fed recording material P is
The skew is corrected by the pair of registration rollers 12, and is supplied to the transfer belt 130 in synchronization with the image forming stations Pa, Pb, Pc, and Pd, and is carried on the surface of the transfer belt 130. It is conveyed in the same direction as it rotates in the direction.

Next, the above-mentioned image forming stations Pa, P
The configuration of b, Pc, and Pd will be described. Each of the image forming stations Pa, Pb, Pc, and Pd is provided with a photosensitive drum 3a, 3b, 3c, or 3d as a first image carrier. Around the primary chargers 2a, 2b constituting the process means,
2c, 2d, developing devices 1a, 1b, 1c, 1d, transfer chargers (transfer means) 24a, 24b, 24c, 24d, cleaning devices 4a, 4b, 4c, 4d, pre-exposure device 111
a, 111b, 111c, and 111d are provided, respectively. Further, the above-mentioned photosensitive drums 3a, 3b, 3c, 3
above the photosensitive drums 3a, 3b, 3 after charging.
An exposure device 117 that irradiates laser light onto the surfaces c and 3d to form an electrostatic latent image is provided.

The above-mentioned primary chargers 2a, 2b, 2c, 2d
Is for uniformly charging the surface of the photosensitive drum to a predetermined polarity and potential before exposing the photosensitive drums 3a, 3b, 3c and 3d.
Is a process for developing (visible image) by attaching toners of black, magenta, yellow, and cyan to an electrostatic latent image formed on the surface of the photosensitive drum by exposure. The transfer chargers 24a, 24b, 24c, and 24d transfer toner images formed on the photosensitive drums 3a, 3b, 3c, and 3d to the recording material P.
Reference numerals a, 4b, 4c, and 4d are for removing toner (residual toner) remaining on the surface of the photosensitive drum after the transfer of the toner image onto the recording material P. Pre-exposure units 111a, 11
1b, 111c and 111d are photosensitive drums 3a, 3b,
The exposure device 117 has a semiconductor laser, a polygon mirror, an fθ lens, and the like, and receives an electric digital image signal and modulates the signal in accordance with the signal. The light is transferred to the photosensitive drum 3a,
Irradiation is performed in the generatrix directions 3b, 3c and 3d.

A little downstream of the image forming station Pd along the rotation direction of the transfer belt 130, the recording material P carried on the surface of the transfer belt 130 is transferred to the transfer belt 130 after the toner image is transferred so as to face the transfer belt 130. A separation charger 32 for separation is provided. A transport belt 62 for transporting the separated recording material P is provided downstream of the separation charger 32, and a fixing device 9 for fixing a toner image on the surface of the recording material P further downstream thereof. A paper discharge tray 63 on which the recording materials P are stacked is provided. The fixing device 9 described above
A fixing roller 51 having a heating unit such as a heater therein and a pressure roller 52 pressed against the fixing roller 51 are provided.

Below the transfer belt 130, a belt cleaner 19 for removing unnecessary toner and the like remaining on the surface of the transfer belt 130 is provided. Each of the image forming stations Pa, Pb, Pc, and Pd has a potential detection sensor 113a, 113b, 113c, or 11 that detects the potential of the surface of the photosensitive drum 3a, 3b, 3c, or 3d after exposure.
3d are arranged.

Next, the operation of the above-described image forming apparatus will be described.

When an image formation start signal is input to the image forming apparatus main body 1, the photosensitive drum 3a starts rotating in the direction of the arrow, and is uniformly charged by the primary charger 2a. Next, the exposure device 117 irradiates the surface of the photosensitive drum 3a with a laser beam modulated by an image signal corresponding to a black component of the original image to form an electrostatic latent image.
This electrostatic latent image is supplied with black toner by the developing device 1a to form a black toner image and is developed (visualized).

On the other hand, the recording material P stored in the paper feed cassette 10 is fed by the paper feed roller 11 and the skew is corrected by the registration roller pair 12 which is temporarily stopped. The toner image is supplied onto the transfer belt 130 so as to be synchronized with the toner image formed on the drum 3a. Recording material P supplied to transfer belt 130
The toner image on the photosensitive drum 3a is transferred by the transfer charger 24a in the transfer section (the contact portion between the photosensitive drum 3a and the transfer belt 130) of the image forming station Pa.

The same steps as those in the above-described image forming station Pa are similarly performed in the remaining three image forming stations Pb, Pc, and Pd, so that magenta, yellow, and cyan toner images are formed. The images are sequentially transferred onto the recording material P.

Recording material P on which transfer of four color toner images has been completed
Is separated from the transfer belt 130 while being subjected to AC static elimination by the separation charger 32, and is conveyed to the fixing device 9. The recording material P is heated and pressurized here to fix the toner image on the surface, and then discharged onto the discharge tray 63.

The maximum image width in the above-described image forming apparatus is about 290 mm on the side of A4, and the peripheral speed of the photosensitive drums 3a, 3b, 3c and 3d is 300 mm / sec.
It is.

FIG. 2 is an enlarged vertical sectional view of the photosensitive drum 3a. The photosensitive drum 3a includes a conductive substrate 31 such as an aluminum substrate, a charge generation layer 32 coated on the surface thereof, a charge transport layer 33 coated on the surface of the charge generation layer 32,
A release layer 34 is provided on the surface of the charge transport 33. The other three photosensitive drums 3b, 3b
Since c and 3d have the same configuration, the description is omitted.

Next, the cleaning device 4a will be described with reference to FIG. The cleaning device 4a includes a cleaning container 41, a back plate 42 fixed to the cleaning container 41, and a cleaning blade 43 as a cleaning member held by the back plate 42.

The cleaning blade 43 is a 2 mm-thick elastic blade mainly composed of urethane (urethane rubber), and has a hardness of 77 (Shore hardness HS) and a rebound resilience of 4 mm.
1%, (rebound resilience at 40 ° C. 63%), 300% modulus 200 kgf / cm ² (200 × 9.8 N / cm
² , all according to JIS standards). Also,
The cleaning blade 43 contacts the photosensitive drum 3a with a contact angle of 24 ° and a contact pressure of 33 gf / cm (33 × 9
(80 dyne / cm), and is held by the back plate 42. The back plate 42 is a 1 mm-thick stainless steel plate member. Cleaning blade 4
The length of the portion protruding from the third back plate 42, the so-called free length L, is 10 mm. Since the other three cleaning devices 4b, 4c, and 4d have the same configuration,
Description is omitted.

As the pre-exposure device 111a, a light emitting diode (element GaAl) mainly having a peak wavelength of 660 nm is used.
As), the half width at which the peak wavelength is １ ／ is about 2
5 nm, and the exposure amount is 20 μJ / cm ² . The photosensitive drum 3a rotates from the pre-exposure device 111a to the primary charger 2a in about 50 msec.

As shown in FIG. 1, the fixing device 9 is provided inside the fixing roller 51, the pressure roller 52, the heat-resistant cleaning members 54 and 55 for cleaning them, and the fixing roller 51 and the pressure roller 52. Roller heating heaters 56 and 57, an application roller 50 that applies a release agent oil such as dimethyl silicone oil to the fixing roller 51,
An oil reservoir 53 and a thermistor 58 for detecting the temperature of the surface of the pressure roller 52 and controlling the fixing temperature are provided. The recording material P to which the four-color toner image has been transferred is subjected to color mixing of the toner image and fixation to the recording material P by the fixing device 9 to form a full-color copy image.

As a color toner used in this embodiment, a mixture of a polymerized toner produced by a suspension polymerization method and a resin magnetic carrier produced by a polymerization method was used as a two-component developer. The weight (T / D ratio) of the toner relative to the total weight of the obtained developer was 8%. The magnetic carrier has a magnetization of 100 emu / cm ³ in a magnetic field of 1 kOe, a number average particle diameter of 40 μm, and a specific resistance of 10 ¹³ Ω.
Cm used. The non-magnetic polymerized toner is a substantially spherical toner having a smooth surface with a shape factor SF1 (described later) of 115 and SF2 (described later) of 110, a weight average particle diameter of 8 μm, and a specific gravity of 1.05 g. / C
m ³ , a toner having an average charge per unit mass of 25 μC / g was used.

Here, the shape factors SF1 and SF2 will be described.

Scanning electron microscope F manufactured by Hitachi, Ltd.
Using an E-SEM (S-800), 100 toner particles are randomly sampled, and the image information is sampled through an interface using an image analyzer (Lu, manufactured by Nireco Corporation).
zex3) and analyzed, and the values calculated by the following equation were defined as shape factors SF1 and SF2.

SF1 = ｛(MXLNG) ² / (ARE
A) {× (π / 4) × 100 SF2 = {(PERI) ² / (AREA)} × (1/4
π) × 100 where AREA: projected area of toner MXLNG: absolute maximum length of toner PERI: peripheral length of toner

When the toner has a perfect spherical shape, both the shape factor SF1 and the shape factor SF2 have a minimum value of 100. As the shape factor SF1 increases, the degree of flatness of the elliptical shape increases as the numerical value increases, and the shape factor SF1 increases.
As for the value of F2, the larger the value, the more the unevenness of the surroundings increases.

The polymerized toner used in the present invention includes:
The shape factor SF1 is 100 to 140 and the shape factor SF
A substantially spherical toner in which 2 is within the range of 100 to 120 is preferable for maintaining high transfer efficiency. The particle diameter of the toner is preferably 6 to 10 from the viewpoint of image quality.
A range of μm is preferable because a good image can be obtained.

In the above-described image forming apparatus, the “paste amount” of the toner on the photosensitive drum in which the fluororesin is dispersed in the release layer 34 of the photosensitive drum by 30% is 0.5 mg / cm ^2.
In a system that does not feed the recording material P, an image corresponding to 100 sheets of A4 size paper is formed, and the spherical toner on the photosensitive drum is removed by the above-described cleaning blade. FIG. 5 shows the results of measuring the linear pressure of the cleaning blade against the photosensitive drum and observing the edge of the cleaning blade when cleaning is performed. The unit of the linear pressure of the cleaning blade (blade) in the drawing is N (Newton) / cm.

As shown in FIG.
At 0 × 10 ⁻³ (N / cm), toner slippage occurred, and 250 × 10 ^{−3 to} 550 × 10 ⁻³ (250 × 1
0 ⁻³ , 300 × 10 ⁻³ , 400 × 10 ⁻³ , 500
× 10 ⁻³ , 550 × 10 ⁻³ ), neither slippage nor chattering (abnormal vibration) of the toner occurred, and chattering occurred at 600 × 10 ⁻³ .

From the above results, in the above-described configuration, the linear pressure A of the cleaning blade against the photosensitive drum for performing good cleaning at the beginning of use of the image forming apparatus is equal to the linear pressure A of the release layer of the photosensitive drum. When the addition ratio of the fluororesin is 30%, 200 × 10 ⁻³ <A <600 × 1
It was determined to be 0 ^-3 (N / cm). The coefficient of dynamic friction μ between the photosensitive drum surface and the cleaning blade
Does not depend on the linear pressure of the cleaning blade with respect to the photosensitive drum, and in the following embodiment, the linear pressure A is 200 × 10 ⁻³ <A <600 × 10 ⁻³ (N / c
The description will be made assuming that 400 × 10 ⁻³ (N / cm) within the range of m).

Here, a method of measuring the dynamic friction coefficient μ will be described.

When the photosensitive member serving as the image bearing member is in the form of a sheet, a flat plate, or an endless (endless) belt, the dynamic friction coefficient μ between the cleaning blade and the surface of the photosensitive member.
Is usually a surface property tester (model H
It is measured by EIDON-14). The cleaning blade is pressed against the photoreceptor with a constant load (gf), and the force (gf) applied when the cleaning blade is moved in parallel with the photoreceptor surface in this state is measured. The coefficient of kinetic friction μ is [force applied to photoconductor (gf)] / [load applied to blade (gf)] when blade starts to move.
Is obtained.

However, the photoreceptor incorporated in the electrophotographic image forming apparatus is a drum-type photoreceptor drum mainstream, and the dynamic friction coefficient μ in this case is equal to the rotational torque T1 (kgf · cm) of the photoreceptor drum itself. The rotational torque T2 (kgf · cm) of the system in which the residual toner after the transfer process is interposed on the photosensitive drum in a state where the cleaning blade is pressed against the load F (kgf) is measured and calculated by the following equation. Desired.

Μ = (T2−T1) / (F · γ) where γ is the radius (cm) of the photosensitive drum.

(Example 1) In the above-described image forming apparatus, the photosensitive member has a surface roughness Rz of 1.5 and a fluororesin (for example, Teflon (registered trademark)) for the outermost release layer. 30% dispersed, at room temperature,
In a normal humidity environment, 20,000 copies were actually printed on 100 continuous copies of an image having a coverage of 10%, and the image obtained on the 20,000th copy was visually evaluated. The results are shown in FIG. When the dynamic friction coefficient μ was 0.48, the cleaning property was good. Note that the surface roughness Rz shown here is a 10-point average surface roughness defined by JIS B0601.

(Example 2) The same structure as that of the above-mentioned Example 1 was used except that the surface roughness Rz of the photosensitive member was 1.5 and the ratio of the fluororesin dispersed in the release layer was 20%. 10 continuous copies with 10% image coverage under normal temperature and normal humidity environment
A real copy test of 20,000 copies was performed with 0 copies, and the image obtained on the 20,000th copy was visually evaluated.
Shown in The coefficient of kinetic friction μ between the photoreceptor surface and the cleaning blade increases due to the decrease in fluororesin,
However, since the cleaning blade was within the allowable range, no turning or chatter of the cleaning blade was observed.

(Example 3) The same structure as in Example 1 was used, except that the surface roughness of the photoreceptor was 1.5 and the ratio of the fluororesin dispersed in the release layer was 10%. The actual initial polishing of the release layer was performed with a surface roughness Rz of 3.0 (μm), and at room temperature and normal humidity, 100,000 copies of an image coverage of 10% were continuously printed on 20,000 copies. The image obtained on the 20,000th sheet was visually evaluated, and the results are also shown in FIG. The coefficient of kinetic friction μ between the photoreceptor surface layer and the cleaning blade is increased to 1.28 by the surface roughness brought about by the initial polishing of the releasable layer, and becomes 1.28. Was done.

(Comparative Example 1) In comparison with Example 3,
A photoreceptor having an initial polished surface roughness of 3.0 and a release layer of fluororesin of 0%, 20,000 copies of 100% continuous image copy at 100 ° C under normal temperature and normal humidity environment Was carried out, and the image obtained on the 20,000th sheet was visually evaluated. The results are also shown in FIG. The dynamic friction coefficient μ increased to 3.11, and chipping of the cleaning blade occurred.

(Example 4) The initial polishing of the surface of the photoreceptor was performed using Rz.
= 0.2, and a photoreceptor having a release layer of 30% fluororesin was subjected to a real-life test of 20,000 copies of 100 continuous copies at a normal temperature and normal humidity of 100% at an image coverage of 100%. The image obtained on the tenth sheet was visually evaluated, and the results are also shown in FIG. Due to the effect of the fluororesin, the dynamic friction coefficient μ was suppressed to 2.53, and the image was good.

(Comparative Example 2) In comparison with Example 4,
The initial polishing was set to Rz = 0.2, and a photoreceptor having a release layer of 20% fluororesin under normal temperature and normal humidity environment with an image coverage of 1
An actual photographing test of 20,000 copies of 100% 0% copies was performed, and the image obtained on the 20,000th copy was visually evaluated. The results are also shown in FIG. The dynamic friction coefficient μ is 2.
Due to the increase to 88, chipping of the cleaning blade occurred.

(Comparative Example 3) In comparison with Example 3,
A photoreceptor having an initial polishing of Rz = 3.0, a fluororesin in a release layer of 30%, and a normal temperature, normal humidity environment, 100% continuous image copy of 20,000 copies at 100% image coverage. A test was performed, and the image obtained on the 20,000th sheet was visually evaluated. The results are also shown in FIG. The dynamic friction coefficient μ is 0.
34, the coefficient of friction is too low, the power of the cleaning blade to scrape off the residual toner is reduced,
Slippage of the residual toner from the blade edge was observed.

(Example 5) In comparison with Example 3,
A photoreceptor having an initial polishing of Rz = 4.0 and a fluororesin in a release layer of 10%, and in a normal temperature and normal humidity environment, 100,000 copies of an image coverage of 10% were continuously printed on 20,000 copies. A test was performed, and the image obtained on the 20,000th sheet was visually evaluated. The results are also shown in FIG. Due to the effect of the surface roughness, the dynamic friction coefficient μ was reduced to 1.18, and the cleaning property was good.

(Comparative Example 4) In comparison with Example 3,
A photoreceptor having an initial polishing of Rz = 5.0 and a fluororesin in a release layer of 10%, and in a normal temperature and normal humidity environment, 100,000 continuous copies of an image coverage of 20,000 copies at 100 continuous copies. A test was performed, and the image obtained on the 20,000th sheet was visually evaluated. The results are also shown in FIG. Although the coefficient of kinetic friction μ was within the allowable range for cleaning, the residual toner slipped from the blade edge portion due to the excessively large surface roughness Rz.

Example 6 A photoreceptor having an initial polishing of Rz = 0.1 and a fluororesin in a release layer of 40% was used to continuously copy 10% of the image coverage 10% under normal temperature and normal humidity environment.
A real copy test of 20,000 copies was performed with 0 copies, and the image obtained on the 20,000th copy was visually evaluated.
Shown in Even in a system in which the fluororesin is present in an excessive amount of 40%, the cleaning was satisfactorily performed when the surface roughness was set to Rz = 0.1.

(Comparative Example 5) In comparison with Example 6,
Photoreceptor with initial polishing Rz = 0.1 and fluororesin in the release layer of 50%, with 100% continuous copy of 20,000 copies at 10% image coverage under normal temperature and normal humidity environment. A test was performed, and the image obtained on the 20,000th sheet was visually evaluated. The results are also shown in FIG. Due to the presence of too much fluororesin, μ was excessively reduced to 0.38, and residual toner slipped from the blade edge.

FIG. 4 shows the above results. The figure shows the amount of Teflon (registered trademark) (content of the fluororesin contained in the release layer of the photoreceptor) and the surface roughness by the initial polishing, which can perform good cleaning in the image forming apparatus. It shows the relationship with Rz.

"Good cleaning area" in FIG.
The dynamic friction coefficient μ between the photosensitive member and the cleaning blade falls within the range of 0.5 to 2.5.

According to the present invention, when the amount of Teflon (registered trademark) is 10
% To 40% and Rz of the photoreceptor surface is 5%
By performing these optimal combinations within a range of less than μm, the dynamic friction coefficient μ that enables good cleaning can be obtained.
In the range of 0.5 to 2.5.

Thus, the above-mentioned JP-A-4-33538
No. 7 and Japanese Unexamined Patent Publication No. 11-218953 discloses a range (range) of a good dynamic friction coefficient for cleaning.
In the present invention, it is possible to obtain a range that is twice as large as 1.0, which is 2.0. Therefore, it is possible to easily adjust to this range and obtain stable cleaning performance.

In a system in which the coefficient of dynamic friction μ exceeds 2.5, in order to favorably clean a spherical toner having a high roundness as described in the present invention, it is necessary to use an image carrier (photoconductor). It is essential to apply a high blade pressure to the cleaning blade, in which case chipping or chatter of the cleaning blade occurs. On the other hand, in a system in which the coefficient of dynamic friction μ is less than 0.5, the adhesion between the image carrier (photoconductor) and the edge of the cleaning blade is lost, and conversely, Spherical toner easily penetrates the blade edge, causing image defects.

That is, according to the present invention, toner having a high roundness, which has conventionally been considered difficult to clean,
This has the advantage that good cleaning properties can be ensured without adding a cleaning aid (lubricant) to the edge of the blade. Further, in order to clean the spherical toner having a high roundness satisfactorily, it is necessary to apply a higher blade load to the surface of the photoreceptor than in the case of the irregular toner. In this case, chipping of the cleaning blade, Permanent strain and shear stress tend to increase,
By defining the dynamic friction coefficient μ as described above, chipping, permanent set, and shear stress can be reduced,
Further, there is also an effect of preventing the toner from being fused due to an increase in the heat generation amount of the cleaning blade.

As a result, the reliability of the image forming apparatus can be greatly improved, and the productivity can be increased.

In the above description, as the image forming apparatus, the toner image formed on the photosensitive drums 3a, 3b, 3c and 3d is recorded on a recording material (second material) carried on a transfer belt 130 as a recording material carrier. The image forming apparatus of the type in which the image is directly transferred to the image carrier P is described. However, the present invention is not limited to such an image forming apparatus, and can be used, for example, in an image forming apparatus using one image carrier.
Furthermore, the present invention can be applied to an image forming apparatus using an intermediate transfer body as the second image carrier.
That is, once the toner image formed on the photosensitive drum is
The present invention can also be applied to an image forming apparatus in which primary transfer is performed on an intermediate transfer member (for example, an intermediate transfer drum or an intermediate transfer belt), and then secondary transfer is performed on the recording material P from the intermediate transfer member. Note that the recording material P in this case is different from
, But a so-called third image carrier.

In the above embodiment, an example using a non-magnetic polymerized toner has been described. However, the present invention is not limited to this, as long as it is a substantially spherical toner.

[0090]

As described above, according to the present invention,
When cleaning the substantially spherical toner, it is possible to prevent the cleaning blade from being damaged or causing poor cleaning, and to obtain stable cleaning performance.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a schematic configuration of an image forming apparatus according to the present invention.

FIG. 2 is a longitudinal sectional view for explaining a layer configuration of a photoreceptor.

FIG. 3 is a longitudinal sectional view showing a configuration of a cleaning device.

FIG. 4 is a graph showing the relationship between the amount of Teflon (registered trademark) and the surface roughness Rz with respect to cleaning performance.

FIG. 5 is a diagram showing a relationship between a linear pressure of a cleaning blade and an evaluation of a blade edge portion.

FIG. 6 shows the photoreceptor surface roughness, photoreceptor Teflon (registered trademark)
6 is a table for explaining the amount, the coefficient of dynamic friction between the photosensitive member surface and the blade, and the image evaluation after 20,000 copies.

[Explanation of symbols]

3a, 3b, 3c, 3d First image carrier (photoconductor, photoconductor drum) 4a, 4b, 4c, 4d Cleaning device 24a, 24b, 24c, 24d Transfer unit (transfer charger) 34 Release layer 43 Cleaning member (cleaning blade) 130 Recording material carrier (transfer belt) P Second image carrier (recording material)

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) G03G 15/01 G03G 9/08 384 (72) Inventor Hisakataka Kukuni 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon In-house F term (reference) 2H005 AA15 AA21 AB06 EA10 2H030 AB02 AD01 BB02 BB21 BB43 2H068 AA04 AA06 AA08 AA09 AA54 BB31 FA03 FA04 FB13 2H134 GA01 GB02 HD05 HD07 HD11 HD19 KD08 KG07 KG08 KH01 KH15

Claims (14)

[Claims] 1. A first image carrier for carrying a toner image formed by substantially spherical toner on a surface thereof, and a transfer for transferring the toner image on the surface of the first image carrier to a second image carrier. An image forming apparatus comprising: The first image carrier has a surface containing a fluororesin, the content F (% by weight) of the fluororesin is 10 ≦ F ≦ 50, and the surface roughness of the surface of the first image carrier is Rz (μm) is Rz <5.0, and a coefficient of kinetic friction μ between the surface of the first image carrier and the cleaning member is 0.5 ≦ μ ≦ 2.5. Image forming apparatus. 2. The image carrier according to claim 1, wherein the first image carrier has a plurality of layers on the surface side, and a surface layer of the plurality of layers contains a fluororesin. The image forming apparatus as described in the above. 3. The image bearing member according to claim 1, wherein the first image bearing member has a surface roughness R.
3. The image forming apparatus according to claim 1, wherein the surface is polished so that z is in a range of Rz <5.0. 4. 4. The toner has a weight average particle size R (μm)
The image forming apparatus according to any one of claims 1 to 3, wherein is within a range of 6 ≦ R ≦ 10. 5. The toner has a shape factor SF1 of 100.
≦ SF1 ≦ 140, and the shape factor SF2 is 1
The image forming apparatus according to claim 4, wherein the range is 00 ≦ SF2 ≦ 120. 6. The cleaning member has a linear pressure A (N / cm) in contact with the surface of the first image carrier in a range of 200 × 10 ⁻³ <A <600 × 10 ⁻³ . The image forming apparatus according to any one of claims 1 to 5, wherein 7. The image forming apparatus according to claim 1, wherein the cleaning member is a cleaning blade having elasticity. 8. The cleaning blade according to claim 1, wherein:
The image forming apparatus according to claim 7, wherein the image forming apparatus contacts the moving direction of the surface of the image carrier in a counter direction. 9. The image forming apparatus according to claim 8, wherein the cleaning blade is formed of urethane rubber. 10. The image forming apparatus according to claim 1, wherein the toner is a non-magnetic toner. 11. The image forming apparatus according to claim 1, wherein the toner is manufactured by a polymerization method. 12. A recording material carrier that carries and conveys the second image carrier, and a plurality of the first image carriers provided along a moving direction of the recording material carrier. 2. The toner image formed on each of the plurality of first image carriers is sequentially transferred onto a second image carrier carried and conveyed by the carrier. 3. 12. The image forming apparatus according to any one of claims 11 to 11. 13. The image forming apparatus according to claim 12, wherein the toner images formed on the plurality of first image carriers are toner images of different colors. 14. A method according to claim 1, wherein the first image bearing member has a radius γ (cm).
When the cleaning member is not in contact with the surface of the first image carrier, the dynamic friction coefficient μ of the first image carrier is T1 ( kgf · cm), the rotational torque at the time of contact is T2 (kgf · cm), and the contact load at the time of contact is F (kgf), μ = (T2−T1) / The image forming apparatus according to any one of claims 1 to 13, wherein the value is a value obtained by the equation (F · γ).