JPH0460668A - Developing device - Google Patents

Abstract

PURPOSE:To prevent the clogging and flocculating of a toner in the contact part between a developer regulating member and a developer carrying member and the fusion of the toner onto the developer regulating member by forming a resin layer contg. a solid lubricant in this contact part. CONSTITUTION:The resin layer 15 contg. the solid lubricant is provided in the contact part between the developer regulating member 5 and the surface of the developer carrying member 4. Namely, the solid lubricant is incorporated into the resin layer 15, by which the surface of the resin layer 15 is chipped on repetition of printing and the fresh surface of the resin layer 15 is incessantly exposed and renewed. The clogging and flocculating of the toner T, etc., in the contact part between the developer carrying member 4 and the developer regulating member 5 are obviated and the fusion of the toner T, etc., on the developer regulating member 5 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. The present invention relates to a developing device used to develop an electrostatic latent image formed on an image bearing member in an image forming apparatus such as an electrophotographic device, and particularly relates to a developing device that uses a one-component developing method for developing. The present invention relates to a developing device using an agent.

In an image forming apparatus such as an electrophotographic apparatus, an electrostatic latent image formed on an image carrier is developed by a developing device and visualized as a toner image.

As a developing method using such a developing device, Japanese Patent Application Laid-Open No. 1986-
No. 43036, etc., uses a magnetic toner as a -component developer, applies a very thin layer of toner onto a developing sleeve, triboelectrically charges it, and then applies the toner under the action of the magnetic field of a magnet built into the developing sleeve. A method has been proposed in which the electrostatic latent image on the image carrier is developed in close proximity to and without contact with (opposed to) the electrostatic latent image.

With this method, by applying an extremely thin layer of toner onto the developing sleeve, the opportunity for contact between the developing sleeve and the toner is increased, and sufficient frictional electrification of the toner is possible. By supporting the toner and moving the magnet and the toner in the opposite direction, the toner particles are disaggregated and the toner is sufficiently rubbed against the developing sleeve. By developing the material facing each other without coming into contact with it, it is possible to prevent blurring due to the
Excellent images can be obtained.

In addition, as a developer regulating method, by bringing a developer regulating member made of an elastic material such as urethane rubber into contact with the developing sleeve, a protrusion is formed at the abutting part between the developing sleeve and the developer regulating member).
A method has been proposed in which a thin layer of toner is applied onto a developing sleeve. This method has the advantage that since the toner is actively charged at the contact portion of the elastic blade with the developing sleeve, the image density increases and a better image can be obtained.

However, the performance of the above method is greatly affected by the temperature and humidity conditions or the surface properties of the developer regulating member and the developing sleeve. For example, in conditions where the fluidity of the toner is reduced due to high humidity or high temperature, the agglomeration of toner cannot be sufficiently resolved by magnetic force, which has the disadvantage of causing a decrease in image quality and image density. .

In addition, in all developing methods using component developers, it is necessary to form a relatively thin and uniform toner layer on the developing sleeve, but the formation of such a toner layer depends on the environmental conditions, the physical properties of the toner, and the developing sleeve. Depending on the physical properties of the surface, it is not possible to obtain a uniform toner layer, and the toner layer often becomes uneven, especially in a low humidity environment.

Furthermore, when copies are repeated, toner becomes clogged and aggregates between the abutting portions of the developing sleeve and the developer regulating member, resulting in unstable toner charging and unstable toner conveyance of the developing sleeve.

In addition, as copies are repeated, the toner is repeatedly rubbed against the developing sleeve and the developer regulating member, resulting in non-developing substances being fused and deposited on the developer regulating member, or the binding resin in the toner being mixed with the developer. Since the developer is fused and formed into a film on the regulating member, the surface properties of the developer regulating member may change.

As a result of the above, conventionally, streaks and unevenness have occurred in images obtained by development, which has been a problem.

Therefore, an object of the present invention is to prevent toner from clogging and agglomerating in the abutting portion between the developer carrier and the developer regulating member, and from fusion of toner and the like onto the developer regulating member. Accordingly, it is an object of the present invention to provide a developing device that can form a thin layer of toner on a developer carrier and obtain an image without streaks or unevenness through development.

The above-mentioned objects for achieving the following are achieved by the developing device according to the present invention. To summarize, the present invention supports a component developer contained in a developer container on a developer carrier, and forms a thin layer of the developer by a developer regulating member in contact with the surface of the developer carrier. In the developing device, the developer is conveyed by the developer carrier to a developing section facing the image carrier to develop the latent image formed on the image carrier while forming the latent image. The developing device is characterized in that a resin layer containing a solid lubricant is provided at a contact portion with the surface of the developer carrier.

Look up l Examples of the present invention will be described in detail below.

FIG. 1 is a schematic diagram showing an embodiment of the developing device of the present invention. This embodiment describes a developing device used in a laser beam printer using a reversal development method.

In FIG. 1, reference numeral 1 denotes an electrophotographic photosensitive drum on which an electrostatic latent image is developed by the present developing device. The photosensitive drum l is
A negative potential Vd, for example V, is applied by a primary charger (not shown).
After being uniformly charged to d=-650V, it is exposed to light by an exposure means such as a laser beam (not shown), for example, at a potential Vf.
A negative electrostatic latent image with f=-100V is formed.

As shown in FIG. 1, this developing device includes a developing sleeve 4 disposed facing a photosensitive drum 1 in a developing container 7 containing toner T of a -component developer. Developing sleeve 4
is made of a nonmagnetic conductive material such as aluminum, and its surface is roughened by sandblasting or the like. The developing sleeve 4 supports the toner T in the developing container 7 by the magnetic force of the magnet roll 3 contained therein, rotates in the direction of the arrow, and transfers the toner T to a developing section where the photosensitive drum 1 and the developing sleeve 4 face each other. and transport.

An elastic blade 5 is provided above the developing sleeve 4 and contacts the developing sleeve 4 in a counter direction opposite to the rotating direction of the developing sleeve 4 . The elastic blade 5 applies a linear pressure of 15 g/c mQ to the developing sleeve 4 (in its longitudinal direction 1c
The toner T carried on the developing sleeve 4 is regulated and the toner T is thinner than the minimum gap between the photosensitive drum l of the developing section and the developing sleeve 4. A layer 8 is formed on the developer sleeve 4. The toner layer 8 on the developing sleeve 4 is made to stand up by the developing magnetic pole of the magnet roll 3.

A developing bias is applied to the developing sleeve 4 by a bias power supply 6. The developing bias is, for example, a voltage obtained by superimposing a DC voltage of -500 V on an AC voltage such as a rectangular wave with a peak-to-peak voltage of 1400 V and a frequency of 1800 Hz.
The electrostatic latent image on the photosensitive drum 1 is developed by the toner T constituting the upper toner layer 8 .

In this example, the following negatively chargeable high resistance magnetic toner was used as the magnetic toner T.

Styrene-butyl methacrylate copolymer (copolymerization ratio =
8=2, Mw=270,000) ・100 parts magnetic powder (magnetite, BET value 8.0 mm”/g)
...50 parts low molecular weight polypropylene (Mw
=6000)...4 parts Negative charge control agent (chromium complex of monoazo dye)...
... 2 parts The above components are mixed and kneaded, coarsely pulverized, finely pulverized, and classified to obtain a toner classified product with a volume flattened particle size of 10 μm, and 100 parts by weight of this toner classified product is added with toner fluidity improving and/or
Alternatively, for the purpose of toner charge control, for example, 0.9 parts by weight of silica fine particles treated with dimethyl silicone oil may be externally added.
The components were mixed to obtain a negatively chargeable high resistance magnetic toner.

Now, according to the present invention, in order to prevent toner T, etc. from clogging and agglomerating in the abutting portion between the developing sleeve 4 and the elastic blade 5, and to prevent the toner T, etc. from fusing onto the elastic blade 5. In addition, a resin layer 15 containing a solid lubricant is provided at the contact portion of the elastic blade 5 with the developing sleeve 4. In this embodiment, as shown in FIG. 2 which shows an enlarged view of the contact portion of the elastic blade 5 with the developing sleeve 4, the elastic blade 5
is the thickness t-'1. 0 mm, and a resin layer 15 is provided thereon with a thickness of 5=20 μm. The elastic blade 5 is made of urethane rubber with a rubber hardness of 60°.

The formulation of the resin layer 15 containing the above solid lubricant is as follows.

(Formulation) Resin: Phenol resin (solid content) 30 parts by weight Conductive lubricant: Artificial graphite (average particle size 7 μm) 25 parts by weight Diluent: Methyl alcohol + 200 parts by weight of methyl cellosolve Prepared to the above composition 5 to 100 μm of resin liquid is applied to the surface of the elastic blade 5 by spraying or dipping.
The solid lubricant-containing resin layer 15 was formed on the elastic blade 5 by coating the solid lubricant to a certain film thickness and then thermally curing it in a drying oven at 15° C. for 30 minutes. The resistivity of this resin layer 15 was about 1.0 x 10'' to 1.0 x IO'' Ωcm.

In this embodiment, the resin tank 15 containing the above solid lubricant is
Using the elastic blade 5 having the following characteristics in the developing device shown in FIG.
The electrostatic latent image on the photosensitive drum 1 was developed, and an image was formed and printed. As a result, even after printing 10,000 sheets, the wear of the resin layer 15 of the elastic blade 5 is about 3 μm.
Resin powder, etc. in the toner T was not fused to the elastic blade 5.

In addition, within the contact portion between the developing sleeve 4 and the elastic blade 5,
It also had the effect of preventing aggregation due to toner T clogging, and it was possible to eliminate streaks and unevenness on the obtained image. This is because the solid lubricant contained in the resin layer 15 causes the surface of the resin layer 15 to be scraped as printing is repeated, and new surfaces of the resin layer 15 constantly appear and are renewed. Furthermore, since the resistance of the resin layer 15 was small, the charging of the toner T was not adversely affected.

As described above, in the present invention, since the resin layer 15 is worn due to friction with the developing sleeve 4, the surface shape such as surface roughness of the resin layer 15 may be rough, and therefore the formation of the resin layer 15 is difficult. It also has the advantage of being easier.

In the above embodiment, artificial graphite, which is a conductive lubricant, was used as the solid lubricant contained in the resin layer 15, but molybdenum disulfide, boron nitride, etc. could also be used, and similar effects could be obtained. Further, the resin constituting the resin layer 15 is not limited to phenol resin, and thermosetting resins such as epoxy and melamine, and ultraviolet curable resins can also be used.

Further, although an example has been described in which the resin layer 15 contains only a solid lubricant, the resin layer 15 may further contain conductive fine particles such as carbon for the purpose of reducing the electrical resistance of the resin layer 15. can.

Another embodiment of the developing device of the present invention will be described.

The developing device of this embodiment is characterized in that the elastic blade 5 is made of an elastic resin material such as polyethylene terephthalate (PET).

Conventionally, attempts have been made to use resin elastic bodies as elastic blades, but although resin elastic bodies have the advantage of being lower in cost than rubber elastic bodies, they have a Young's modulus of 2 to 3.
Since the hardness is significantly higher, when the elastic blade made of the resin elastic body is brought into contact with the developing sleeve 2, it is difficult to form a uniform nip between the elastic blade and the developing sleeve 2.

In the present invention, even if the elastic blade 5 is made of an elastic resin material, since the resin layer 15 containing a solid lubricant is formed, a uniform nip can be formed at the contact portion with the developing sleeve 4. .

In this example, the elastic blade 5 was made of polyethylene terephthalate with a thickness of 0.5 mm, and a resin layer 15 containing a solid lubricant was formed thereon to a thickness of about 50 μm using the same formulation as in the previous example. This elastic blade 5 is
Used in the developing device shown in the figure, 20 g /
It was used by contacting with a linear pressure of cm, and was developed in the same manner as in the previous example, and an image was formed and printing was repeated.

As a result, although the abrasion of the resin layer 15 at the contact portion of the elastic blade 5 with the developing sleeve 4 was increased, a uniform nip could be ensured through repeated printing, and the toner T to the elastic blade 5 could be maintained evenly through repeated printing. No more fusion (no streaks or unevenness on the image).

In all of the above embodiments, the toner T of the -component developer is
A high-resistance magnetic toner is used as a magnetic toner, and this is regulated by an elastic blade 5- to form a toner layer 8 on a developing sleeve 4 made of non-magnetic metal such as aluminum. In the contact state, the developing sleeve 4
Although a developing device that performs development by applying a developing bias in which a direct current is superimposed on an alternating current has been described, the present invention is not limited thereto.

The developing sleeve 4 may be a metal sleeve whose surface is coated with a conductive resin, or impression molded with a conductive resin, and the surface thereof may be roughened. Further, as the developing bias applied to the developing sleeve 4, only a DC voltage can be applied.

Further, the present invention can also be applied to a developing device using the following developing method.

That is, another embodiment of the developing device of the present invention shown in FIG.
Non-magnetic toner is used as the toner T of the one-component developer in the developing container 7, and the developing sleeve 4 is made of metal such as stainless steel.
Toner T is applied and supported by a conductive sponge roll 30, and an elastic blade 5, which has a resin layer 15 containing a solid lubricant formed on the contact portion with the developing sleeve 4, is attached to the developing sleeve 4 in the direction of rotation thereof. By contacting in the same direction as the forward direction, the toner T carried on the developing sleeve 4 is regulated to form a thin toner layer, and the toner T on the developing sleeve 4 and the photosensitive drum 1 are brought into contact with each other in the developing section. Under non-contact conditions, a DC voltage or a voltage obtained by superimposing AC voltage thereon is applied as a developing bias voltage to the developing sleeve 4 by the bias power supply 6,
This is a method for performing development.

Still another embodiment of the developing device of the present invention shown in FIG. A conductive sponge roll 30 is used to apply and carry toner T on the developing roll 42, and an elastic blade 5 having a resin layer 15 containing a solid lubricant formed on the lower surface that will be in contact with the developing roll 42 is attached to the developing roll 42. The developing roll 4 is in vertical contact with the
regulating the toner T on 2 to form a thin toner layer;
In the developing section, while the toner T on the developing roll 42 is in contact with the photosensitive drum 1, a bias power supply 6 applies a DC voltage or a voltage obtained by superimposing an AC voltage to the developing sleeve 4 as a developing bias voltage to perform development. This is a method that allows you to

Still another embodiment of the developing device of the present invention shown in FIG. N
By rotating the magnet roll 3 having alternating poles and south poles in a direction opposite to the rotational direction of the developing sleeve 4, the toner T is supported and conveyed onto the developing sleeve 4, and the contact portion with the developing sleeve 4 is conveyed. A resin layer 15 containing a solid lubricant in
By abutting the elastic blade 5 formed with the developing sleeve 4 in the counter direction opposite to the rotating direction of the developing sleeve 4,
The toner T on the developing sleeve 4 is regulated to form a thin toner layer, and the toner T on the developing sleeve 4 is in contact with the photosensitive drum l in the developing section, and the bias power supply 6 is applied to the developing sleeve 4 as a developing bias. A method is adopted in which development is performed by applying a DC voltage or a voltage obtained by superimposing an AC voltage on the DC voltage.

In these developing devices, the resin layer 15 containing a solid lubricant is formed at the contact portion of the elastic blade 5 with the developing sleeve 4 or the developing roll 42, so that the elastic blade does not come into contact with the developing sleeve 4 or the developing roll 42. It is possible to prevent toner T, etc. from clogging and agglomerating in the contact area with the developing sleeve 5, and to prevent toner T, etc. from fusing onto the elastic blade 5. It is possible to form a good layer and obtain an image without streaks or unevenness by development.

As explained above, in the developing device of the present invention, a resin layer containing a solid lubricant is formed at the contact portion of the developer regulating member with the developer carrier, so that the contact between these members is It can prevent toner etc. from clogging and agglomerating on the developer regulating member, and it can prevent toner etc. from clogging and agglomerating on the developer regulating member, and it can form a thin layer of toner on the developer carrier. Through development, an image without streaks or unevenness can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the developing device of the present invention. FIG. 2 is an explanatory diagram showing an enlarged view of the contact portion of the elastic blade with the developing sleeve of the developing device shown in FIG. 1. FIG. FIG. 3 is a schematic diagram showing another embodiment of the developing device of the present invention. FIG. 4 is a schematic diagram showing still another embodiment of the developing device of the present invention. FIG. 5 is a schematic diagram showing still another embodiment of the developing device of the present invention. 1: Photosensitive drum 3: Magnet roll 4: Developing sleeve 5: Elastic blade Bias power source Resin layer containing solid lubricant Sponge roll Developing roll Toner Figure 3 Figure 4 Figure 2

Claims (1)

[Claims] 1) A one-component developer contained in a developer container is supported on a developer carrier, and while a thin layer of the developer is formed by a developer regulating member in contact with the surface of the developer carrier, In a developing device that transports the developer by a developer carrier to a developing section facing the image carrier and develops a latent image formed on the image carrier, the developer is carried by the developer regulating member. A developing device characterized in that a resin layer containing a solid lubricant is provided at a portion in contact with a body surface.