JP2517649B2 - Powder developer conveying member, method of manufacturing the same, and developing device having the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention conveys a powder developer applied to an image forming apparatus such as an information recording device such as an electrophotographic copying machine, an electrophotographic laser beam printer, and an LED printer. The present invention relates to members (sleeve, belt, roller, magnet roller) and a dry developing device including the same. More specifically, the present invention relates to a manufacturing method for forming a carrying surface of a developer carrying member to an appropriate surface shape, a manufactured carrying member, and a developing device having the same.

[Background technology]

A developing device using a developer conveying member (hereinafter referred to as a sleeve) blasted with regular particles or irregular particles is described in JP-A-57-66455 and JP-A-57-116372.

The sleeve blasted with the irregular particles has an excellent property that the one-component developer is appropriately triboelectrically charged and the carrying force is stable.

However, the stainless steel (SUS316) sleeve has a grain size #
Using a surface-roughening sleeve sand-blasted with 400 amorphous particles and conducting a continuous copying test using small-sized toner particles in order to further raise the image quality level in recent years, the following phenomenon occurred.

(1) When the continuous copying operation was continued, the image density decreased from 1.3 to 1.0 when 2000 to 5000 sheets were printed.

(2) When an image of a solid black surface is printed with a developing device having a reduced image density, an image appears as white with a low image density corresponding to the sleeve rotation cycle.

(3) When the toner on the sleeve surface was removed by the developing device in (2) and then the solvent was further cleaned on the sleeve and image formation was performed, the image density was recovered.

Then, first, when the triboelectric charge amount of the toner in development (1) was measured, it was found to be half or less of the charge amount at the start, and it was found that the decrease in the charge amount lowers the image density.

Similarly, when the development (2) was examined, white spots were also due to the decrease in the charge amount. However, it is presumed that the correction shown in phenomenon (3) is against the fact that the sleeve caused the problem rather than the deterioration of the toner. Therefore, when the sleeve was observed with an electron microscope or the like, it was possible to observe a state in which something was embedded in the concave and convex portions of the surface, especially the concave portions. Analysis of this material showed it to be a resin binder in the components of the toner. Since the concave portions are covered with the binder, the toner is also a resin, so that the resin and the resin frequently come into contact with each other, and sufficient charge cannot be obtained, and the toner charge amount is reduced. In particular, it was found that the resin was strongly adhered to the deep part of the recess and was blasted with the irregular-shaped particles, so that the sharpness of the uneven shape further strengthened the adhesion.

Next, since it was found that a resin with a sharp uneven shape adheres to the sleeve surface, the above problem can be solved by using a sleeve having a rough surface with smooth unevenness by blasting with regular particles. Conceivable. Therefore, when continuous copying was performed using a sleeve that had been subjected to sandblasting using regular particles of particle size # 400, most were good, but under special conditions, the following problems were newly generated.

(4) The image density gradually decreased when copying about 2000 to 5000 sheets of an original with a lot of white background with extremely small toner consumption.

(5) When several solid black copies were continuously made with the developing device in which the image density was lowered, the image density began to recover.

(6) When copying was performed in a low temperature environment, the image density immediately decreased, and uneven coating of the developer occurred in places on the sleeve surface.

Then, a toner particle layer was attached to the surface of the sleeve in the development (4), and it was confirmed by measuring the charge amount thereof that it was considerably higher than the charge amount of the applied toner amount at the start. Further, when the particle size of the adhered toner is measured, the particle size of 1 to
The toner was mainly 5 .mu.m, and the particle size was obviously smaller than the particle size (7 to 12 .mu.m) of the toner mainly contained in the container.

These phenomena (4-6) will be examined. First, when toner is charged by friction with the rough surface of the sleeve, a charge of the opposite polarity to the toner is induced on the sleeve,
It is adsorbed on the sleeve by the mirroring force that attracts it, but at this time, the minute toner (1 to 5μ) has a larger charge amount than most toner (7 to 12μ), so the minute toner is thinly coated on the sleeve surface. Will end up. The thin toner layer interferes with the contact of the toner that contributes to the development with the sleeve, and the toner having the particle size that most contributes to the development is not sufficiently charged by friction, resulting in a decrease in density (when measuring the charge amount, The amount of charge is measured to measure the total amount of toner). When the humidity is low, the charging amount up of the fine toner is further expanded, so that the conveying force of the toner supplied to the sleeve is reduced, and there is a problem under special conditions such that coating unevenness occurs.

Since the surface of the sleeve blasted with the regular particles is a rough surface composed of smooth minute concave surfaces, the surface of the toner with respect to the sleeve surface of the toner is larger than that of the rough surface composed of sharp irregularities blasted with the irregular particles. It is estimated that the contact area becomes wider and the triboelectric charge amount increases. In any case, such a characteristic causes an excessive friction band amount of the fine toner, which causes the inconvenience.

In particular, the process of forming an oscillating electric field in the developing section to attach and detach the toner to and from the electrostatic latent image holding member is repeated, and finally, an amount of toner corresponding to the potential of the latent image is applied to the latent image holding member. In the developing method to be left above, moderate charging is desired in order to oscillate the toner well.

[Object of the Invention]

An object of the present invention is to solve the drawbacks of a developer conveying member blasted with irregular particles and a developing device using the same, and a drawback of a developer conveying member blasted with regular particles and a developing device using the same. It is to solve the problem, prevent the charge amount of the developer from decreasing, and stabilize the carrying force of the developer.

[Outline of Invention]

In the present invention, the developer carrying member used is blasted with a mixture of fixed particles and irregular particles. As a result, the non-adhesion amount of the resin component of the toner can be reduced, the adhesion amount of the fine powder toner can be reduced, the charge amount can be stabilized over a long period of time, and the conveying force can be stabilized.

〔Example〕

In FIG. 1, reference numeral 1 is a latent image holding member, which is usually an electrophotographic photosensitive member and is hereinafter referred to as a photosensitive drum. Reference numeral 2 is a well-known electrostatic latent image forming unit, 3 is a developing device according to the present invention for visualizing a latent image, and 4 is a toner image on the photosensitive drum which has been visualized and transferred onto a transfer material. A well-known transfer separation unit 5 for separating the material from the drum is a well-known cleaning unit for cleaning the residual toner on the drum. As the developer, a magnetic toner in which magnetic particles are bound in resin is used.

An electrostatic latent image is formed on the photosensitive drum 1 by the latent image forming unit 2. Further, the photosensitive drum rotates in the direction of arrow A and reaches the developing device 2. The developing device 2 includes a container hopper 10 for containing a magnetic toner as a one-component developer, an agitating means 9 for feeding the toner from the hopper 10 to the vicinity of the sleeve and a fluidity of the toner, and a fixed magnet 8 on the outside thereof. A non-magnetic sleeve 7 that rotates in the direction of arrow B is provided. The sleeve 7 conveys the toner to the developing unit facing the drum 1 and applies the toner to the drum.

The thickness of the toner layer on the sleeve 7 is determined by the magnetic blade 6 facing the magnetic pole N ₁ of the magnet 8 with the sleeve in between.
(See US Pat. No. 4,387,664). At the developing position facing the sleeve and the drum, the toner is supplemented by the developing magnetic pole S ₁ , and the toner on the sleeve 7 flies and is visualized by the electric field between the latent image on the drum 1 and the sleeve. At this time, a developing bias voltage is applied to the sleeve 7 by the developing 11 so that the toner easily fly. Power supply for sleeve 7
Apply alternating bias voltage by 11. As a result, the toner flying from the sleeve 7 toward the drum 1 is repeatedly attached to and detached from the drum 1, and finally, that is, when the drum leaves the developing portion, the toner corresponding to the potential of the latent image is transferred to the drum. It remains on the drum in an attached state.

The alternating voltage includes not only a peak value alternately appearing positive and negative but also a voltage oscillating only on the positive voltage side or only on the negative voltage side. The present invention is also useful for a developing device that applies the alternating bias voltage to the sleeve 7 to form an oscillating electric field in the developing portion, but can also be applied to a developing device that applies a DC bias voltage to the sleeve.

The toner on the drum is transferred to the transfer material at the transfer section 4, and is fixed to the transfer material at the fixing section (not shown). On the other hand, the residual toner on the drum is cleaned by the cleaning unit 5, and then the latent image is formed.

 The specifications of an example of the device are as follows.

The strength of the magnet 8 is N ₁ pole: 850 on the surface of the sleeve 7.
gauss, S ₁ pole: 950gauss, N ₂ poles: 750gauss, S ₂ poles: 550gauss
Is. The minimum distance between the sleeve 7 and the drum 1 was 0.3 mm, and the distance between the sleeve 7 and the blade 6 was 0.25 mm. Therefore, a toner layer thinner than the gap between the sleeve and the drum is conveyed to the developing section. Power supply 11 is peak-to-peak voltage 1300
A voltage obtained by superimposing a DC voltage of −200 V on an AC voltage of V and a frequency of 1600 Hz is applied to the sleeve 7. The photoconductor is OPC, and the dark part (darkest part of the image) potential is -650V and the light part (non-image part) potential is -150V. Copy speed is A4 size paper every minute
20 sheets. The sleeve 7 has a diameter of 20 mm, and its surface is blasted using stainless steel SUS316. The sleeve may be made of aluminum or titanium steel other than stainless steel.

The mixed blasting agent used for the blasting treatment was # 400 Al ₂ as irregular blasting abrasive grains (grains with a rough surface).
Use O ₃ and use # 400 glass beads as standard blast abrasives (spheres with smooth surface or flat particles are good)
It was mixed at a ratio of 1: 1. This mixed material, 12 rpm
The sleeve rotating at was separated by 100 mm from this sleeve. Pneumatic pressure 3Kg / m ^{2 with} 7mm diameter nozzle
I sprayed with. The nozzle is moved parallel to the axis of the sleeve a distance of 30 cm in 1-2 minutes. The sleeve surface is washed in the washing step after the above sandblasting, and then dried. A copying operation was performed using the developing device having the above-described structure. As a result, even if the number of continuously copied sheets is increased, the toner coating on the sleeve is not uneven, and the image density is always constant and high. Moreover, a solid black original was copied after continuous copying, but no white image was generated. Further, although several thousand originals having many solid white areas were copied, the image density did not decrease. In this example, the ratio of the abrasive grains of the irregular shape and the regular shape was set to 1: 1. There is an advantage in that the mixing ratio with the relatively smooth recessed area can be made uniform and excellent in operational effect. In the present invention, this mixing ratio is not limited to the ratio in the above example.

When the developing sleeve after the above treatment was further confirmed by an electron microscope, the surface thereof had the following structure.

That is, as shown in FIG. 4, a fine rough surface area R formed by collision of irregular particles and a relatively smooth concave area (dimple) S formed by collision of fixed particles are mixed. There are many sharp fine projections in the rough surface area R, and sharp projections are rarely seen in the relatively smooth concave area S. And the relatively smooth recessed areas do not all have the same surface property, but each is 0S, 0.2S, 0.8S, 1.
There are mixed recessed areas with different surface roughness, such as having a roughness of 6S. That is, minute areas having different surface roughness are mixed on the sleeve surface.

Next, a second embodiment will be described with reference to FIG. The same members as those in FIG. 1 are designated by the same reference numerals. The feature of the present embodiment is that the magnetic field is not used to control the thickness of the toner layer,
Flexible elastic member such as a rubber blade that abuts the sleeve 7.
To use twelve. By using the blade 12 for toner layer regulation, 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 is also low. FIG. 2 uses a two-pole magnet roller 13. The magnetic field strength on the surface of the sleeve is S ₁ pole: 600 gauss, N ₁ pole: 500 gauss, other conditions of the bias power supply 11, and the gap between the sleeve drums are the same as in the first embodiment.

The blade 12 is brought into contact with the sleeve 7 at a pressure of about 2 to 10 g per 1 cm in the sleeve axial direction. The blade 12 is made of urethane rubber having a thickness of 0.8 to 1 mm, or various kinds of rubber such as neoprene rubber and nitrile rubber. An example is a plastic sheet. PET sheet 100μ Polyamide sheet, polyimide sheet, etc.

Urethane rubber was used in this example. The sleeve 7 was made of stainless steel SUS316, and its surface was blasted. As the mixed blast treatment agent, # 600 silicon carbide was used as the irregular blast abrasive grains, and # 400 glass beads were used as the regular blast. At this time, since the blade 12 is of a type in contact with the sleeve, the surface of the sleeve is made smoother than in Example-1. Therefore, the ratio of the irregular blasting abrasive grains to the mixture ratio of the irregular blasting abrasive grains and the regular blasting abrasive grains is reduced to 2: 8 or 3: 7. The conditions for spraying onto the sleeve are the same as in the first embodiment. An image was formed by the developing device 3 using the sleeve thus sandblasted. Even when continuous copying progressed, neither uneven coating of toner on the sleeve 7 nor defect image having toner fusion on the sleeve, black streaks, etc. occurred, and a stable high-density image was obtained.

Even in the sleeve of this example, the surface of the sleeve has a large number of sharp projections formed by the collision of irregular particles, and the sharp projections formed by the collision of the regular particles and the fine rough surface area are rarely seen. A relatively smooth concave area is mixed.
However, since the proportion of the shaped particles in the mixed blasting material is high, the number of relatively smooth recessed areas is relatively increased as compared with that in the first embodiment.

In the present specification, the roughness measurement was carried out with a fine surface roughness meter sold by Taylor Boblin Co., Ltd., Kosaka Laboratory, etc. FIG. 3 shows the measuring method of the roughness. In this FIG. 3, the average roughness Rz = 1.5 under the following measurement conditions.
μ, pitch = 19 μ.

Here, the surface roughness is JIS 10-point average roughness (Rz) [JIS B06
01]. That is, as shown in FIG. 3, a straight line parallel to the average line A of the reference length l extracted from the cross-section polar line and passing through the third peak from the highest direction (shown in the figure) and the deeper one Although it passes through the third valley bottom (indicated by'in the figure) from, the gap between the two straight lines is expressed in micrometers (μm), and the reference length l = 0.25 mm. The pitch of the pitch is 0.1
Those with a height of μ or more are counted as one mountain, and the reference length is 0.
Based on the number of peaks in 25 mm, it was calculated as follows.

{250 (μ) / (number of peaks included in 250 (μ))} (μ) Here, the reason why the blast treatment with the mixture of the irregular blast abrasive grains and the regular blast abrasive grains is good will be examined.

When the average charge amount of the toner in Example 1 was measured, it was found to be reduced by about 8 to 10% of the triboelectric charge amount at the start after copying 2000 continuous sheets. After that, there was almost no change in the charge amount. That is, it means that the amount of triboelectricity due to the contact of the toner with the sleeve was kept substantially constant without the fine particle toner covering the surface of the sleeve. Even when the surface of the sleeve is observed, the amount of resin or the like attached is small. Then, the roughness of the sleeve surface was measured and found to be Rz = 1.5μ and pitch 30-35μ. Rz = 1.5μ when blasting only with irregular blast abrasive grains,
The pitch is 15 to 20 μ, and it can be seen that the pitch is longer and the number of convex portions is reduced as compared. Moreover, when the surface is observed with an electron microscope, the shape of the recess formed by the collision of the fixed particles is smooth, and the resin or the like is difficult to adhere. Therefore, it is difficult for the binder resin of the toner to adhere to the concave portion, and the appropriate convex portion formed by the collision of the irregular particles is mixed with the concave portion and the triboelectric charge amount of the toner does not become too high. The number of sharp protrusions is reduced, but the number of sharp protrusions is maintained at a moderate number.The irregularities of the surface formed by collision of irregular blast abrasive grains are reduced by the regular blast abrasive grains. This is because the repeated steps of colliding the irregular-shaped blast abrasive grains with each other are performed next. Due to the irregular blast abrasive grains and the regular blast abrasive grains mixed in this way, an appropriate number of sharp convex portions (and these convex portions are often due to irregular particles) and smooth concave portions (the concave portions are due to regular particles) A good image is always maintained by the number of (a lot of things).

For confirmation, as described in JP-A-58-11974, when the blast treatment of the irregular blast abrasive grain was first performed after the blast treatment of the regular blast abrasive grain, the pitch became longer and the recess became smooth, but Rz = 0.5μ, and the sharp protrusions were crushed by the regular blast abrasive and became smaller. Further, when the regular blast treatment was performed first and then the irregular blast treatment was performed, the smooth concave portion became rough and eventually the irregular blast treatment itself was performed.

When the average charge amount of the toner was measured in Example-2, after the continuous copying of 2000 sheets, it was reduced by about 6 to 8% with respect to the friction charge amount at the start. After that, there was almost no change in the charge amount. That is, the triboelectric charge amount due to the contact of the toner with the sleeve was always kept substantially constant without the fine particle toner covering the surface of the sleeve. The amount of resin adhering to the sleeve surface is also very small. The roughness of the sleeve was Rz = 1.2 μm and the pitch was 35 to 50 μm.

Next, preferable conditions for the present invention will be described.

In the present invention, the developer may be a dry powder developer such as a one-component developer or a mixture of a carrier and toner particles (two-component developer). It is preferable that the admixture containing particles is uniformly mixed.

In addition, the number A of regular particles and the number B of irregular particles
When A / B is 1/20 or more and 9/1 or less, the above effect can be favorably obtained without being affected by these particle sizes. Furthermore, this A /
When B is 1/2 or more and 4/1 or less, the balance between the fine rough surface area and the relatively smooth concave area is stable, and the unit areas of different surface roughness are evenly distributed. Can be surely obtained. In addition, the size of standard particles is JIS R6001,
# 40 or more and # 800 or less, the size of irregular particles is JIS R6001 #
It is preferably 50 or more and # 1000 or less.

Next, the average particle size C of the regular particles and the average particle size D of the irregular particles were C / D of 1/10 or more and 10 or less, respectively, in the experiment. More preferably, if C / D is 1/2 or more and 4/1 or less, it is possible to form relatively smooth concave portions due to the regular particles and relatively minute irregularities due to the irregular particles, and various different surface states. It is possible to surely obtain the unit areas in the uniform distribution state.

Further, among the above, on the surface of the developer transport member that achieves a more stable effect, the size of the recess formed by the collision of the fixed particles in the developer transport direction is 5 μm or more.
It is considered that the roughness is 100 μm or less, the depth is greater than 0 μm and 10 μm or less, the rough surface portion formed by the collision of irregular particles is 2 μm or more and 50 μm or less, and the average roughness Rz is 0.1 μm or more and 8.0 μm or less. This is because it is difficult to distinguish between the concave portion formed by the collision of the regular particles and the rough surface formed by the irregular particles in the above-mentioned measurement method, so the surface blasted with the regular particles only, the blast treatment with the irregular particles only This is an estimation based on the results of measuring the respective surfaces.

The amorphous particles used for the mixed blasting agent may be silicon carbide particles, alumina particles, iron trioxide particles, or titanium dioxide particles, and the fixed particles may be glass beads, steel balls, or ferrite balls. Any of the flat ferrite particles may be used, but the present invention is not limited to these.

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

Further, in the above-described embodiment, the developer layer which is thinner than the sleeve / drum gap is conveyed to the developing section, but the present invention is a developing device which conveys a developer layer equal to or hotter than the sleeve / drum gap to the developing section. Can also be applied to.

The present invention is useful for toners having an average particle diameter of 3 to 10 μm, but is not limited to this.

〔The invention's effect〕

According to the present invention, the triboelectrification and the transportability of the developer can be stabilized for a long period of time, and a good developed image can be obtained.

[Brief description of drawings]

1 and 2 are explanatory views of an embodiment of the developing device of the present invention, FIG. 3 is an explanatory view for explaining the roughness measurement of the surface of the conveying member, and FIG. 4 is an enlarged cross-sectional view of the surface portion of the conveying member. It is a schematic diagram. Reference numeral 1 is a latent image holding member, 3 is a developing device, and 7 is a non-magnetic sleeve.

Claims (9)

(57) [Claims] 1. A powder developer carrying member for carrying and carrying a powder developer, characterized in that the developer carrying surface is blasted with a mixture of amorphous particles and fixed particles. A powder developer carrying member for 2. A method of manufacturing a powder developer carrying member for carrying and carrying the powder developer, wherein the developer carrying surface of the carrying member is blasted with a mixture of amorphous particles and fixed particles. A method for manufacturing a powder developer carrying member, which comprises the step of: 3. The irregular particles include any one of silicon carbide, alumina, silicon dioxide, iron oxide, and titanium oxide, and the regular particles are glass beads, steel balls, ferrite balls, and flat particles. 3. The method for manufacturing a powder developer carrying member according to claim 2, wherein any one of the farite particles is contained. 4. A developing device comprising a developing member which forms a developing portion facing a latent image carrier and conveys the powder developer to the developing portion, wherein the amount of the powder developer conveyed to the developing portion is A regulating member is provided on the side of the powder developer carrying surface of the carrying member for regulating, and the powder developer carrying surface of the carrying member is blasted with a mixture of amorphous particles and fixed particles. The developing device is characterized by being provided. 5. The developing device according to claim 4, further comprising a power supply unit for forming an oscillating electric field in the developing section. 6. The developing device according to claim 4, wherein the regulating member is an elastic member that is in contact with the conveying member. 7. The regulating member is a magnetic member disposed in the conveying member with a gap, the conveying member is a non-magnetic body, and a static magnet having a magnetic pole facing the regulating member is provided inside the conveying member. The developing device according to claim 4, wherein the developing device is arranged. 8. The conveying member is blasted with a mixture having an A / B of 1/20 or more and 9/1 or less, where A is the number of regular particles and B is the number of irregular particles. The developing device according to any one of claims 4 to 7. 9. The conveying member has an average particle diameter of the fixed particles of C,
When the average particle size of irregular particles is D, C / D is 1/10 or more 1
The developing device according to claim 4, wherein the developing device is blasted with a mixed agent having a ratio of 0/1 or less.