JP2692051B2 - Method for roughening the surface of the developer carrier - Google Patents

Description

The present invention relates to a developer carrying member applied to an image forming apparatus such as an information recording device, and a developing for a developing device equipped with the developer carrying member. The present invention relates to a method for roughening the surface of an agent carrier.

[Prior Art] Conventionally, when carrying one component magnetic developer on the surface of a developer carrier such as a sleeve (hereinafter simply referred to as "sleeve") while conveying the developer to a developing area. It is known that roughening the surface of the sleeve improves its transportability. As a method for roughening the surface of such a sleeve, for example, as disclosed in JP-A-57-66455, irregular blast particles (hereinafter referred to as irregular blast particles having sharp edges such as angular powder particles on the sleeve surface) are disclosed. There is a method of blasting with amorphous particles). According to this method, the one-component developer is agitated by the roughened surface so as to be in an appropriately charged state, and the coating of the developer on the sleeve is also stable. .

[Problems to be Solved by the Invention] (A) However, on a stainless steel (SUS 305) sleeve, amorphous particles having a grain size of # 400 (the grain size standard depends on that of the JIS R6001 abrasive material; the same applies hereinafter) When a continuous copying test was carried out using toner particles as a developer using a surface-roughening sleeve blasted with only the toner, the following problematic phenomena occurred.

When the continuous copying operation was continued in the normal temperature and normal humidity environment, the image density decreased from 1.3 to 1.2 after copying 5,000 sheets. Further, when the continuous copying operation was continued in a low temperature and low humidity environment, the image density decreased from 1.3 to 1.1 when 5,000 sheets were printed.

That is, it is conceivable that the image density is reduced as described above because the electric charge (hereinafter referred to as tribo) applied to the toner due to frictional charging is not sufficient. Generally, the toner tribo tends to increase in a low-temperature and low-humidity environment, but even in such an environment, the image density decreases as described above, and the tribo is insufficient.

(B) On the other hand, a stainless steel (SUS 305) sleeve is used instead of the above-mentioned irregular particles, and regular blast particles having a smooth surface such as spherical powder or granular powder particles of particle size # 400 (hereinafter referred to as regular particles). The following phenomenon occurred when a continuous copying test was conducted using toner particles using a sleeve blasted with only the toner.

When continuous copying is continued in a room temperature and normal humidity environment, 5000
The image density was as good as 1.35 for one sheet. Further, when the continuous copying operation was continued in a low temperature and low humidity environment, the image density was as good as 1.3 at 5000 sheets. However, uneven application of toner on the sleeve occurred. That is, in this case, although the tribo is sufficiently applied, it is considered that the tribo is further increased in the low temperature and low humidity environment and the toner uneven coating is generated.

(C) In addition, stainless steel (S
US 305) sleeves are blasted with amorphous particles having a particle size of # 600 and then blasted with spherical particles that are regular particles having a particle size of # 800 smaller than the amorphous particles. When a continuous copying test was conducted using the particles, the following phenomenon occurred.

When the continuous copying operation was continued at room temperature and normal humidity, the image density was as good as 1.3 at 5000 sheets. When the continuous copying operation was continued in a low-temperature and low-humidity environment, the image density was as good as 1.25 after every 5,000 sheets, but uneven toner coating occurred.

Therefore, although the shortage of tribo in the case of blasting only the irregular particles was improved, it is understood that the tribo is not suppressed in the low temperature and low humidity environment.

(D) Furthermore, a stainless steel (SUS 305) sleeve was mixed at a ratio of 1: 1 with amorphous particles having a particle size # 400 similar to (A) and regular particles having a particle size # 400 similar to (B). A method of blasting with particles is proposed in Japanese Patent Application No. 62-196570. According to this method, good results were obtained with respect to the image density and toner application to the sleeve, but there is a drawback that the management of particles becomes complicated. That is, the shape of the irregular particles and the regular particles, due to the difference in strength due to the material, that the service life is different, the exchange cycle is difficult to determine because of the inability to separate the two, the shape of the abrasive grains,
Since the weight and particle size distribution are different, in order to maintain the mixing ratio,
It is necessary to perform uniform dispersion as a mixing operation on a regular basis, which is bothersome and may cause the shortening of the abrasive grain life.
In view of the above points, there is a problem that it is practically difficult to adopt.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and provides a proper amount of tribo while preventing uneven toner coating on a sleeve, and a developer carrier for a developing device capable of obtaining a stable image regardless of the environment. It is an object to provide a surface roughening method.

[Means for Solving the Problems] According to the present invention, the object is to blast the surface with irregular-shaped abrasive particles and leave the previously-polished surface with the regular-sized abrasive particles having a larger particle size. It is achieved by blasting.

[Operation] As described above, in the present invention, the projection surface of the projection of the uneven portion formed on the sleeve surface is sharper than the surface of the recess, so the frequency of contact with the toner is reduced, and the occurrence of tribo is suppressed. Since the sharp protrusions are dull on the surface in comparison with the surface of the protrusions, the contact frequency with the toner increases and tribo is positively imparted. Therefore, the amount of tribo imparted to the toner is made appropriate.

[Embodiment] An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram of an image forming apparatus having a developing device as a first embodiment of the present invention.

In the figure, 1 is a latent image holding member, which is usually a photoconductor (hereinafter referred to as "photosensitive drum"), 2 is an electrostatic latent image forming portion, 3 is a developing device for visualizing a latent image, and 4 is a developing device. A transfer separation unit 5 for transferring the visualized toner image on the photosensitive drum to a transfer material is a cleaning unit for cleaning the residual toner on the photosensitive drum.

 The image forming apparatus functions as follows.

First, a latent image is formed on the photosensitive drum 1 by the electrostatic latent image forming unit 2. Further, the photosensitive drum 1 rotates in the direction of arrow A, and the area where the latent image is formed reaches the developing device 3. The developing device 3 is a hopper which is a container for containing toner.
10, a stirring means 9 for feeding the toner from the hopper 10 to the vicinity of the sleeve 7 as a developer carrying member and enhancing the fluidity of the toner, a fixed magnet 8 and further rotating the outside of the magnet 8. Although the non-magnetic sleeve 7 is provided, the present invention is not limited to this.

Further, the thickness of the toner layer on the sleeve 7 is equal to the opposing magnetic pole N ₁
It is regulated by the magnetic blade 6 which is regulated together with it.
On the sleeve 7, at the position facing the photosensitive drum 1, the developing magnetic pole
The toner stands up by S ₁ and the toner on the sleeve 7 flies to the photosensitive drum 1 due to an electric field (preferably an oscillating electric field such as AC) between the latent image on the photosensitive drum 1 and the sleeve 7 to form a visible image. To do. At this time, a developing bias is applied to the sleeve 7 so that the toner may easily fly (DC may be used, but alternating electric field in this example).
Is applied by the bias power supply 11. The visualized toner image on the photosensitive drum 1 is transferred to a transfer material (not shown) at the transfer separation unit 4, and the toner image on the transfer material is fixed at a fixing unit (not shown). . On the other hand, the surface of the residual toner on the photosensitive drum 1 is cleaned by the cleaning unit 5 to prepare for the next latent image formation.

Next, the magnet and the sleeve in the image forming apparatus as described above will be described.

First, the magnet 8 is a cylinder, and the magnetic pole strength of each pole shown in the figure is N ₁ : 1000 [gauss], S ₁ : 1000 on the surface of the sleeve 7.
[Gauss], N ₂ : 750 [gauss], S ₂ : 550 [gauss], the shortest gap between the sleeve 7 and the photosensitive drum 1 is 0.25 mm, and the gap between the sleeve 7 and the magnetic blade 6 is 0.25 mm. Held in. In addition, as the bias power supply 11, the one in which DC is superimposed on AC is used, and its voltage V _pp (peak to peak) is 1400 V,
Development was carried out by superimposing 120 V DC on AC having a frequency f of 1800 Hz, and speed copying processing was performed at 80 sheets per minute on A4 size paper.
The photosensitive drum 1 is A-Si, and the dark portion potential is set to 400V and the light portion potential is set to 70V.

The sleeve 7 was made of stainless steel (SUS 305) and had an outer diameter of 32 mm, and its surface was blasted. The sleeve 7 may be made of stainless steel, aluminum, or titanium steel.

The blast condition of the sleeve surface in this example is # 40 as amorphous particles (particles having sharp angles like horny powder particles).
For a sleeve rotating at 12 rpm using Al ₂ O ₃ of 0 (average particle diameter 35 to 45 μm according to JIS R6001 abrasive material particle size standard. In the following, the particle size is based on the particle size standard). A nozzle with a diameter of 7 mm and a distance of 150 mm from this sleeve blows air at 3.5 kg / cm ² for 30 seconds, and the nozzle reciprocates a distance of 30 cm parallel to the axis of the sleeve. After that, the sleeve surface is washed and dried in the washing process.

After that, # 100 (average particle size 1) as regular particles (particles with a smooth surface such as spherical powder or granular powder particles)
50-180μm) glass beads (FGB) and air pressure 3.0k
Blasting was carried out at g / cm ² in the same manner as in the case of the amorphous form under other conditions. After that, the washing process was performed as described above. FIG. 2 shows the surface roughness of the sleeve of this embodiment.

Next, when a copying operation was carried out using the developing device of the above-mentioned processing method, there was little fluctuation in density during intermittent copying and continuous copying, and an image density of 1.35 was obtained under both normal temperature and normal humidity. Further, under low temperature and low humidity, an image density of 1.3 was obtained in all cases, and there was no uneven coating of toner on the sleeve surface.

When the surface of the sleeve after the above treatment was observed,
The following structure was confirmed on the surface. That is,
It was confirmed that the concave portions were formed by the large-sized regular particles in the area of about 70 to 80% of the fine-grained blast surface of the irregular-shaped particles, and the fine irregular-blast particles were stored in the concave portions. A large number of sharp fine protrusions were seen on the irregular blast surface of 20 to 30% that was not impacted by the regular particles, but the irregular blast surface of 70 to 80% that was impacted by the regular particles was The sharp fine protrusions were slightly smooth. This indicates that the surface maintains fine protrusions, but parts with different sharpness are mixed.

Next, a second embodiment of the present invention will be described with reference to FIG.

In the figure, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof is omitted.

The feature of this embodiment is that a flexible elastic member such as a rubber blade that is in contact with the sleeve 7 is used instead of using a magnetic field to control the thickness of the toner layer. Toner layer regulation,
By using the blade 12 as shown in FIG. 3, the regulation magnetic pole is not required. Therefore, the number of magnetic poles can be reduced, a small diameter magnet roller can be used, and the cost can be reduced. FIG. 3 uses a bipolar magnet roller 13. The strength of the magnetic pole on the sleeve surface is
S ₁ : 600 [gauss] and N ₁ : 500 [gauss], and other conditions of the bias power supply 11 and the gap between the sleeve 7 and the photosensitive drum 1 are the same as in the first embodiment.

The blade 12 is in contact with the sleeve 7 under a force of about 2 to 10 g per 1 cm in the axial direction of the sleeve, and a possible material of the blade 12 is urethane rubber having a thickness of 0.8 to 1 mm,
In addition to various rubbers such as neoprene rubber and nitrile rubber, plastic sheets can be used. For example, there are a PET sheet having a thickness of 100 μm, such as a polyamide sheet and a polyimide sheet.

Urethane rubber was used in this example. The sleeve 7 was made of stainless steel (SUS 305) and had its surface blasted.

The blasting method was as follows: after the irregular blast treatment of the first embodiment, glass beads of # 200 (average particle size 70 to 90 μm) were used as the regular particles and the air pressure was 2.5 kg / cm ² and other conditions were the same as those of the irregular blast. Processed. After that, when a copying operation was performed using this sleeve that had undergone the washing process, good results equivalent to those of the first embodiment were obtained.

Also in the sleeve of the present embodiment, the surface thereof has a sharp fine projection surface of 7 to 8 formed by collision of irregular particles.
The sharpness of the divided area is blunted by the impact of the regular particles.

Next, a third embodiment will be described. This is larger than that of the first embodiment in the sleeve blasting process of the first embodiment as the regular particles # 30 (average particle size 500 to 700 μm).
The glass beads of m) are used, and the other blast processing conditions and the developing device configuration are the same as those in the first embodiment. When a continuous copying operation was performed in this example, the image density was 1.3 under normal temperature and normal humidity and 1.25 under low temperature and low humidity. Further, uneven toner coating on the sleeve surface did not occur. When the surface of the sleeve used at this time was observed, the area of the portion of the irregularly shaped blasted surface that had been subjected to the regularized blasting was about 30 to 40%, and in the case of the first embodiment (about 7 to 8).
It was smaller than That is, when the conditions such as the air pressure during the fixed blast treatment were fixed, the larger the size of the fixed particles, the smaller the area ratio of the region subjected to the fixed blast treatment.

Next, a first embodiment, which is a comparative experiment with the third embodiment, will be described.

[First Experimental Example] In the sleeve blasting method described in the first example, glass beads of # 600 (average particle size 30 μm) having a diameter smaller than that of the first example were used as the regular particles, and Regarding the conditions, a continuous copying operation was performed using a sleeve that had been subjected to the same treatment as in the first embodiment. as a result,
The image density was as good as 1.35 at both room temperature and normal humidity and low temperature and low humidity, but uneven toner coating on the sleeve occurred at low temperature and low humidity. The surface roughness of the sleeve is shown in FIG.

From the above third embodiment and first experimental example, it is understood that the size of the regular particles used for the blasting treatment has an appropriate range in order to maintain a good image density and obtain a uniform toner coating. If the size of the regular particles is too large, the proportion of the area subjected to the regular blast treatment is reduced, so that the ability to impart tribo to the toner is reduced and it becomes impossible to maintain a good image density. As described in the third example, the upper limit of the size of the regular particles is considered to be about 20 times the size of the irregular particles. In the case of adopting the regular particles larger than this, it is practically inconvenient because it is necessary to increase the air pressure or lengthen the treatment time in the blast treatment in order to enlarge the regular blast region. On the other hand, if the size of the regular particles is smaller than the size of the irregular particles, the regular blast region becomes too large, which is the same as the process of the regular blast only, resulting in uneven coating of toner. Therefore, it is considered that the lower limit of the size of the regular particles is equivalent to the size of the irregular particles.

JP-A-58-11974 describes an invention in which the sleeve surface is sandblasted with irregular particles and then the sandblast treatment with regular particles is performed to blunt the sharpness of fine irregularities formed by the irregular blast treatment. However, the object of the present invention is to prevent the toner particles from sticking to the sharp concave and convex portions, and the size of the regular particles for using the regular particles as a means for blunting sharp concaves and convexes. Must be smaller than the size of the irregular particles.

The present invention is different from the above-mentioned invention, in order to form a wide relatively smooth shaped blast region for imparting tribo, while appropriately leaving sharp fine protrusions of the unshaped blast region, the size of the shaped particles is It must be larger than the size of the irregular particles.

From the above, the appropriate range for the size of the regular particles is
It is 1 to 20 times the size of irregularly shaped particles, and it is especially desirable.
It was 1.5 to 9 times.

As described above, it has been found that the blasting process (overlapping process) with the regular particles after the blasting process with the irregular particles brings good results in the image density and the toner application onto the sleeve.

Next, the second and third experimental examples will be described. In these experiments, either the regular blast treatment or the irregular blast treatment was performed, and the comparison with the first embodiment was performed.

[Second Experimental Example] Amorphous blasting was not performed, and only regular blasting was performed (# 100 or # 300 was air pressure 4.0 kg / c
m ^2, processing time 60 seconds) the image density normal temperature and normal humidity 1.35, but 1.3 low temperature and low humidity is obtained, the toner coating unevenness occurs on the sleeve at a low temperature and low humidity. The condition of the sleeve surface of the second experimental example is shown in FIG.

[Third Experimental Example] In this experimental example, only the amorphous blasting process under the same conditions as in the first example was performed. As for the initial characteristics of the sleeve only with the irregular blast treatment, the concentration was 1.2 or less at both room temperature and normal humidity and low temperature and low humidity, but uneven toner coating did not occur at low temperature and low humidity. The sleeve surface roughness state of the third experimental example is shown in FIG.

When the tribo of the toner on the sleeve surface was measured in the second experimental example and the third experimental example, the second experimental example showed a high tribo value and the third experimental example showed a low tribo value.

From these facts, it was found that the sleeve surface property for obtaining good image density and good toner application should have a part of sharp fine projections and a part of blunted fine projections.

On the surface of the sleeve where the entire surface is blunted or only on the fixed surface, the contact between the toner particles and the surface of the sleeve is actively performed, and the toner tribo increases, but there is no means to suppress the increase and it is abnormally high in some areas. If tribo toner particles are present, they are attracted to the surface of the sleeve by a mirroring force, and it becomes difficult to fly during image formation, which is considered to cause uneven toner coating. In addition, the sleeve surface, which has only fine protrusions on the entire surface, easily captures toner particles mechanically, which hinders the movement of toner particles and reduces the frequency of contact between the sleeve and toner. It is thought that it cannot do. Therefore, it is considered that the regular blast (overlapping process) after the irregular blast has both the function of applying tribo to the toner particles and the function of preventing excessive tribo application.

As the irregular particles, use any of silicon carbide particles, alumina particles, iron trioxide particles, and titanium dioxide particles, and as the regular particles, use glass beads, steel balls, ferrite balls, or flat ferrite particles. However, the present invention is not limited to these.

The developer carrying member is not limited to a cylindrical one, but a cylindrical one or a belt-like one can be used, and a roller of the magnet itself can also be used.

Further, in the above embodiment, the developer layer which is thinner than the gap between the sleeve and the drum is conveyed to the developing unit, but the present invention conveys the developer layer which is equal to or thicker than the gap between the sleeve and the drum to the developing unit. It can also be applied to devices.

The present invention is useful for toners having an average particle diameter of 3 to 15 μm, but is not limited thereto.

[Effects of the Invention] As described above, according to the present invention, the outer surface of the sleeve is finely roughened with irregular particles, and the regular particles having a large average particle diameter are made to collide with each other to form a convex portion. By forming the concave portion having the protrusion surface that is blunted as compared with the protrusion surface, the toner can be provided with appropriate tribo. Therefore, by incorporating the developer carrying member of the present invention as a developing sleeve, the developer can be reliably conveyed and the developing ability can be maintained for a long period of time. It is possible to provide a stable image regardless of the environment.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment device of the present invention, and FIG. 2 is a diagram showing a surface of a developer carrier of the first embodiment device,
FIG. 3 is a schematic configuration diagram showing an apparatus of the second embodiment, FIG. 4 is a diagram showing surface roughness as a result of the first experimental example, and FIG. 5 is a diagram showing surface roughness as a result of the second example. , FIG. 6 is a diagram showing the surface roughness as a result of the third experimental example. 3 ... Developing device 7 ... Developer carrier (sleeve)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hiroaki Tsuchiya 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) Reference JP-A-1-131586 (JP, A) JP-A-63 -304277 (JP, A) JP 59-198480 (JP, A) JP 55-140858 (JP, A) JP 58-11974 (JP, A)

Claims (2)

(57) [Claims] 1. A surface of a developer carrying member characterized in that after blasting the surface with irregular-shaped abrasive particles, blasting is carried out with fixed-sized abrasive particles having a larger particle diameter while leaving the previously polished surface. Roughening method. 2. The method for roughening the surface of a developer carrying member according to claim 1, wherein the average particle size of the regular abrasive particles is 1.5 to 9 times the average particle size of the irregular abrasive particles.