JPH0336562A - Developing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developer carrier applied to image forming equipment such as an information recording device, and a developing device equipped with the developer carrier.

[Prior Art] Conventionally, when carrying a -component magnetic developer on the surface of a sleeve-shaped developer carrier (hereinafter simply referred to as a "sleeve"), the developer is transported to a developing area. It is known that roughening the surface of the sleeve improves its conveyability. As a method for roughening the sleeve surface, for example, as disclosed in Japanese Patent Application Laid-Open No. 57-66455, the sleeve surface can be roughened by roughening amorphous blast particles (hereinafter referred to as "amorphous blast particles") having sharp corners such as angular powder particles. There is a method of blasting using irregularly shaped particles. This method has the advantage that the roughened surface agitates the one-component developer and brings it into an appropriately charged state, while also stabilizing the coating of the developer onto the sleeve. .

[Problems to be solved by the invention] (A) By the way, a grain size well of 400 (the grain size standard is JIS R6) is placed on a sleeve made of stainless steel (SO3305).
001 Depends on the abrasive. When a continuous copying test was conducted using a surface-roughened sleeve that had been blasted with only amorphous particles (the same applies hereafter) and toner particles as a developer, the following problematic phenomena occurred. .

5000 when continuously copying in a room temperature and humidity environment
When copying a sheet, the image density decreased from 1.3 to 1.2. Further, when continuous copying operation was continued in a low temperature and low humidity environment, the image density decreased from 1.3 to 1.1 when 5000 copies were made.

In other words, it is thought that the above-mentioned decrease in image density occurs because the toner is not sufficiently charged with frictional charges (hereinafter referred to as tribo). - In a low-temperature, low-humidity environment inside the shell, the toner triboelectricity tends to increase, or even in such an environment, the image density decreases as described above, indicating a lack of triboelectricity.

(B) On the other hand, a sleeve made of stainless steel (SO5:105) was used instead of the above-mentioned irregularly shaped particles, such as spherical particles with a particle size of #400 or shaped blast particles with a smooth surface such as granular powder particles (hereinafter referred to as fixed particles). ) When a continuous copying test was carried out using toner particles using a sleeve that had been blasted with only 100% polyester, the following phenomenon occurred.

500 when continuously copying in an environment of normal temperature and humidity.
The image density was good at 1.35 when there were no sheets. In addition, when continuous copying operation was continued in a low temperature and low humidity environment, 5
The image density was good at 1.3 when printing 000 sheets. However, uneven application of toner on the sleeve occurred. That is, in this case, the triboelectricity was sufficiently applied, but it is thought that in the low temperature and low humidity environment, the triboelectricity became high and uneven toner application occurred.

(C) Also, as in JP-A-58-11974, after blasting a sleeve made of stainless steel (SUS 3OS) with irregularly shaped particles of particle size #600, particles of #800 particle size smaller than the irregularly shaped particles are used. When a continuous copying test was conducted using toner particles using a sleeve blasted with spherical particles, which are regular-shaped particles, the following development occurred.

5000 when continuously copying at room temperature and humidity
The image density was 1.3, which was good.

Further, when continuous copying operation was continued in a low temperature and low humidity environment, the image density was good at 1.25 after 5000 sheets were printed, but uneven toner application occurred.

Therefore, it can be seen that the lack of tribo in the case of blasting only irregularly shaped particles has been improved, or that tribo in the low temperature and low humidity environment has not been suppressed.

(D) Furthermore, a sleeve made of stainless steel (SO3305) was mixed with irregularly shaped particles of particle size #400 similar to (A).
A method of blasting with particles having a particle size of #400 mixed in a ratio of 1:1 was proposed in the patent application filed in 1986.
2-19657 (l). This method has obtained good results in terms of image density and toner application to the sleeve, but has the disadvantage that particle management is complicated. Due to the difference in strength between the abrasive particles and the shape and material of the abrasive particles, the service life is different, the replacement cycle is difficult to determine because the two cannot be separated, and the shape, weight, and particle size distribution of the abrasive particles Therefore, in order to maintain the mixing ratio, it is necessary to periodically perform a uniform dispersion as a mixing operation, which is troublesome and can shorten the life of the abrasive grains. There was a problem.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a developing device that can prevent uneven toner application on a sleeve while providing an appropriate amount of triboelectric to obtain a stable image regardless of the environment. do.

[Means for Solving the Problems] According to the present invention, the above object is to provide a developing device equipped with a developer carrier having an endlessly movable surface while carrying a developer. The protrusion surface is roughened with sharp protrusions at a fine pitch by colliding irregularly shaped particles with sharp corners. The protrusion surface is formed to have large-pitch wavy concave and convex portions due to the collision of regular-shaped particles having a regular surface, and the protrusion surface is sharper at the four parts than at the convex part.

Because of this, they are distant relatives.

[Function] As described above, in the present invention, the projection surface of the convex part of the uneven part formed on the sleeve surface is sharper than the surface of the concave part, so the frequency of contact with the toner is reduced, suppressing the formation of tribo, and Since the sharp protrusions on the surface of the protrusions are blunted compared to the surface of the convex portions, the frequency of contact with the toner is increased, and the triboforms are actively applied. Therefore, the amount of triboelectricity applied to the toner should be appropriate.

[Example] The present invention will be described in detail below based on the accompanying drawings.

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

In the figure, l is a latent image holding member, which is usually a photoreceptor (hereinafter referred to as a "photosensitive drum"), 2 is an electrostatic latent image forming section, and 3 is W
A developing device for converting the i-image into a visible image, 4 a transfer separation unit for transferring the visualized toner image on the photosensitive drum to a transfer material, and 5 a cleaning unit for cleaning residual toner on the photosensitive drum. It is.

Such an image forming apparatus functions as follows.

First, a latent image is formed on the photosensitive drum l by the electrostatic latent image forming section 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 includes a hopper l, which is a container for storing toner.
O, a stirring means 9 that sends the toner from the hopper lO to the vicinity of the sleeve 7 which is a developer carrier and improves the fluidity of the toner, a fixed magnet 8, and further rotates the outside of the magnet 8. However, the present invention does not rely on this.

Further, the thickness of the toner layer on the sleeve 7 is the same as that of the opposing magnetic pole N1.
It is regulated by a magnetic blade 6 which also regulates it.

On the sleeve 7, the toner stands up in spikes due to the developing magnetic pole S at a position facing the photosensitive drum l, and the sleeve 7 is caused by an electric field (preferably an oscillating electric field such as AC) between the latent image on the photosensitive drum l and the sleeve 7. The upper toner flies to the photosensitive drum 1 and becomes a visible image. At this time, a developing bias (direct current or alternating electric field in this example) is applied to the sleeve 7 by a bias power source 11 so that the toner can easily fly. The visualized toner image on the photosensitive tram l is transferred to a transfer material (not shown) in a transfer separation section 4, and the toner image on the transfer material is fixed in a fixing section (not shown). . - The surface of the residual toner on the photosensitive tram 1 is cleaned in the cleaning section 5 in preparation for the next latent image formation.

Next, in the image forming apparatus described above.

The magnet and sleeve will be explained.

First, the magnet 8 is a cylindrical body, and the various magnetic pole strengths shown in the figure are N, :1000[gaussl] on the surface of the sleeve 7.
, S+: 1000 [gaussl, N,: 75G [g
aussl, St: 550 [gaussJ, the shortest gap between the sleeve 7 and the photosensitive tram 1 was 0.25 mm, and the gap between the sleeve 7 and the magnetic blade 6 was maintained at 0.25 mm. Also, as the bias power supply 11, AC or DC
The voltage V9. (peak-to-peak) is 1400V, AC frequency f or 1800Hz
Developing was carried out by superimposing 120 V DC on the image forming apparatus, and copying was performed at a speed of 80 sheets per minute on A4 size paper. Further, the photosensitive drum 1 was A-3i, and the dark area potential was set to 400V, and the bright area potential was set to 70V.

The material of the sleeve 7 is stainless steel (5US305).
The outer diameter was set to 32 cm and the surface was blasted. The sleeve 7 may be made of stainless steel, aluminum, or titanium steel.

In this example, the blasting conditions for the sleeve surface were as follows: irregularly shaped particles (
Particles with sharp edges such as angular powder particles) $40
0 (average particle size 35 to 45 ←■ Depends on the JIS R60 old abrasive particle size standard. Hereinafter, the particle size will depend on the particle size standard.) Sleeve rotating at 12 rpm using A text 203 On the other hand, the air pressure is 3.5 kg/c by the nozzle of diameter 7 mm located 150 degrees away from this sleeve.
m'' for 30 seconds, and the nozzle is moved back and forth over a distance of 30 cm parallel to the axis of the sleeve.The sleeve surface is then cleaned and dried in a cleaning process.

Furthermore, after that, glass beads (FGB) of #100 (average particle size 150 to 180 μm) were used as regular particles (spherical particles or particles with smooth surfaces such as granular powder particles), and other particles were heated at an air pressure of 3.0 kg/c+s''. Blasting was carried out under the same conditions as for the irregular shape.After that, the cleaning process was carried out as described above.Figure 2 shows the surface roughness of the sleeves of this example.

Next, when a copying operation was performed using a developing device using the processing method described above, there was little variation in density in both intermittent copying and continuous copying, and an image density of about 1.35 was obtained in both cases at room temperature and normal humidity. . In addition, under low temperature and low humidity, both are 1.3
An image density of 100 mL was obtained, and no uneven toner application occurred on the sleeve surface.

When the surface of the sleeve after the above treatment was observed, the following structure was confirmed on the surface. In other words, it was confirmed that in about 70 to 80% of the areas where the irregularly shaped particles were blasted with fine grains, recesses were formed by the thick regular particles, and that the fine grains of the irregularly shaped blast were preserved in the recesses. Ta.

Many sharp microscopic protrusions were observed on the 20% to 30% of the irregularly shaped blasted surface that was not impacted by the regular particles, but on the 70% to 80% of the irregularly shaped blasted surface that was impacted by the regular particles. The sharp microscopic projections had become somewhat smooth. This indicates that while the surface maintains fine protrusions, there are parts with different sharpness.

Next, a second embodiment of the present invention will be described based on FIG.

In addition, in the figure, the same reference numerals are given to the parts common to the first embodiment, and the explanation thereof is omitted.

The feature of this embodiment is that it does not use a magnetic field to regulate the thickness of the toner layer, but instead uses a magnetic field such as a rubber blade in contact with the sleeve 7.
f) Using an A elastic member. By using a blade 12 as shown in FIG. 3 to regulate the toner layer, a regulating magnetic pole is not required.

Therefore, the number of m poles can be reduced, a small-diameter magnet roller can be used, and costs can also be reduced. In FIG. 3, a bipolar magnetic roller 13 is used. The strength of the magnetic pole on the sleeve surface is 5tC600 [ga
ussl, N,: 500 [Gaussl, other conditions of bias power supply 11, sleeve 7 and photosensitive drum l
The gap between and is the same as in the first embodiment.

The plate 12 has a diameter of 2 to log per 1c in the axial direction of the sleeve.
The blade 12 is in contact with the sleeve 7 under a certain amount of force, and the possible material for the blade 12 is urethane rubber with a diameter of 0.8 to 1.
In addition to m-thick ones, various rubbers such as neoprene rubber and nitrile rubber, plastic sheets are also available.For example,
There are PET sheets with a thickness of 100 p and 100 m, polyamide sheets, and polyester sheets.

In this example, urethane rubber was used. Sleeve 7
The material used was stainless steel (SO3305), and its surface was subjected to blasting treatment.

The blasting method used #200 (average particle size 70-90p, average particle size 70-90p,
Blast treatment was carried out under the same conditions as for the amorphous shape using the glass beads (m) at an air pressure of 2.5 kg/a1 and other conditions.

Thereafter, when a copying operation was performed using this sleeve which had undergone a cleaning process, good results comparable to those of the first embodiment were obtained.

In the sleeve of this embodiment as well, the surface of the sleeve has 70 to 80% of the sharp micro-protrusions formed by the collision of irregularly shaped particles, whose sharpness is blunted by the impact of the irregularly shaped particles.

Next, a third embodiment will be described. In the sleeve blasting process of the first example, the size of the regular particles was larger than that of the first example (average particle size 500-70).
0 gm) glass beads are used, and the other frust treatment conditions and the configuration of the developing device are the same as in the first example. When continuous copying was performed in this example, the density of one image was 1.3 at normal temperature and humidity, and 1.3 at low temperature and low humidity.
．． It was 25. Furthermore, no uneven toner application occurred on the sleeve surface. The sleeve surface used at this time is **
As a result, the area of the part subjected to the shape blasting process was about 30% to 40%, which was smaller than that in the first embodiment (about 70% to 80%). That is, it has been found that when the conditions such as air pressure during the shaped blasting process are fixed, the larger the size of the shaped particles is, the smaller the area ratio of the region subjected to the shaped blasting process is.

Next, a first experimental example in which a comparative experiment with the third example was conducted will be described.

[First Experimental Example] In the sleeve blasting method described in the first example, glass beads of #600 (average particle size 30 g m), which have a smaller diameter than those of the first example, were used as regular particles, Continuous copying operations were carried out using sleeves treated in the same manner as in the first embodiment under other conditions. As a result, the image density was good at 1.35 both at room temperature and humidity, and at low temperature and low humidity, but uneven toner application on the sleeve occurred at low temperature and low humidity. The sleeve surface roughness condition is 4th.
As shown in the figure.

From the above third example and first experimental example, it can be seen that there is an appropriate range for the size of the regular particles used in the blasting process in order to maintain good image density and obtain uniform toner application. If the size of the regular particles is too large, the proportion of the area that undergoes the regular blasting process will be small, reducing the ability to impart triboelectric effects to the toner, reducing the ability to achieve good image density by 1
I won't be able to hold 11. As described in the third embodiment, the upper limit of the size of the regular particles is considered to be about 20 times the size of the irregular particles. When using regular particles larger than this, it is necessary to increase the air pressure or increase the processing time in the blasting process in order to enlarge the regular blast area, which is inconvenient in practice. On the other hand, if the size of the regular-shaped particles is smaller than the size of the irregular-shaped particles, the regular-shaped blast area will become too large, resulting in the same process as only regular-shaped blasting, resulting in uneven toner application. The lower limit of the size is considered to be equivalent to the size of irregularly shaped particles.

JP-A-58-11974 discloses an invention in which the surface of a sleeve is sandblasted with irregularly shaped particles, and then the sharpness of fine irregularities formed by irregularly shaped particles is blunted by performing sandblasting with irregularly shaped particles. As described above, the purpose of the present invention is to prevent toner particles from sticking to sharp uneven parts, and in order to use regular shaped particles as a means for blunting sharp four parts and convex parts, the size of the regular shaped particles is It is necessary that the size of the particles is smaller than the size of the irregularly shaped particles.

The present invention differs from the above-mentioned inventions in that the size of the regular particles is adjusted to form a wide and relatively smooth regular blast area for applying tribo, while leaving sharp fine protrusions in the irregular blast area to an appropriate degree. It is necessary that the size is larger than that of irregularly shaped particles.

From the above, an appropriate range of the size of the regular particles is 1 to 20 times the size of the irregular particles, and a particularly desirable range is 1.5 to 9 times.

As mentioned above, it has been found that blasting with irregularly shaped particles followed by blasting with regular shaped particles (overshooting) brings about good results in terms of image density and toner application onto the sleeve.

Next, the second and third experimental examples will be explained. In these experiments, only one of the regular shape blasting treatment and the irregular shape blasting treatment was performed, and comparisons were made with the first example.

[Second Experimental Example] An example in which only regular blasting was performed without irregular blasting (#l mouth 0 or well 300 was set at an air pressure of 4.0
kg/cm'', processed in 60 seconds), the image density was 1.35 at room temperature and humidity, and 1.3 at low temperature and low humidity, but uneven toner application occurred on the sleeve at low temperature and low humidity. FIG. 5 shows the state of the sleeve surface in the two experimental examples.

[Third Experimental Example] In this experimental example, only irregular shape blasting was performed under the same conditions as in the first example. The initial characteristics of the sleeve subjected only to irregular shape blasting were that the density was 1.2 or less at both room temperature and humidity, and at low temperature and low humidity, but uneven toner application did not occur at low temperature and low humidity. The sleeve surface roughness state of the third experimental example is shown in the wSG diagram.

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

From these results, it was found that the surface properties of the sleeve in order to obtain good results in image density and toner application are as follows: some parts have sharp microprotrusions and some parts have blunt microprotrusions.

For protrusions whose entire surface has been blunted or for sleeve surfaces that have been subjected to only shaping processing, the contact between toner particles and the sleeve surface is active, and the toner triboelectricity increases, but there is no means to suppress the increase, and it is abnormally high at the - part. When tribo toner particles are present, they are adsorbed to the sleeve surface by reflection force, making it difficult for them to fly during image formation, and this is considered to be the cause of uneven toner application. In addition, the sleeve surface, which has only sharp micro-protrusions on the entire surface, easily captures toner particles mechanically, which prevents the movement of toner particles, reduces the frequency of contact between the sleeve and toner, and provides sufficient triboelectricity to the toner. It is considered that this is not possible.

Therefore, it is considered that the regular blast (overlapping treatment) after irregular blasting has both the function of imparting triboelectricity to the toner particles and the function of preventing excessive triboelectricity.

In addition, as irregularly shaped particles, use any one of silicon carbide particles, alumina particles, iron trioxide particles, and titanium dioxide particles, and as fixed particles, use any one of glass beads, steel balls, ferrite balls, and flat ferrite particles. However, it is not limited to these.

In addition, the developer carrier is not limited to a cylindrical one;
A cylindrical type or a belt type can be used, and a roller of the magnet 7 itself can also be used.

Furthermore, in the above-described embodiment, a developer layer thinner than the gap between the sleeve and the drum is conveyed to the developing section. It can also be applied to equipment.

Further, the present invention is useful for toners having an average particle size of 3 to 15 microns, but is not limited thereto.

[Effects of the Invention] As described above, according to the present invention, the outer surface of the sleeve is subjected to fine roughening treatment using irregularly shaped particles, and furthermore, regular shaped particles having an average particle size or a large diameter are collided with each other.

In addition, by forming the four parts each having a protrusion surface that is blunter than the protrusion surface of the convex part, it is possible to impart appropriate triboelectricity to the toner.・Thus, by incorporating the developer carrier of the present invention as a developing sleeve, the developer can be reliably transported and the developing ability can be maintained over a long period of time.
It is possible to always provide good images even during continuous copying operations without causing uneven toner application, and it is possible to provide stable images regardless of the environment.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an apparatus according to a first embodiment of the present invention, FIG. 2 is a diagram showing the surface of a developer carrier of the apparatus according to a first embodiment,
Fig. 3 is a schematic configuration diagram showing the device of the second embodiment, Fig. 4 is a diagram showing the surface roughness as a result of the first experimental example, and Fig. 5 is a diagram showing the surface roughness as the result of the second experimental 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)

Claims (2)

[Claims] (1) In a developing device equipped with a developer carrier having an endlessly movable surface while carrying developer, the surface of the developer carrier is finely divided by colliding amorphous particles with sharp corners. The protrusion surface, which is roughened with sharp protrusions at a large pitch, becomes wavy and uneven at a large pitch due to the collision of regular particles with a smooth surface and an average particle diameter larger than the average particle diameter of the irregularly shaped particles. 1. A developing device, characterized in that the protrusion surface is formed to have a portion and the surface of the protrusion is more blunted in the concave portion than in the convex portion. (2) The average particle size of the regular particles is 1 of the average particle size of the irregular particles.
The developing device according to claim 1, wherein the developing device is 20 times larger.