JPH10282785A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device without gushing of developer and excellent in start-up of electrification and replenishment. SOLUTION: In the developing device, a nonmagnetic and one-component developer to which an auxiliary agent is externally added as necessary is supplied to a developer carrier 30 which is rotationally driven and has <=10<13> Ω.cm conductivity, by a developer supplying member 40 having <=10<6> Ω.cm conductivity, so that the developer is held on the surface of the developer carrier 30, and is carried. A latent image carrier makes a formed electrostatic latent image to be a visible image with the developer carried on the developer carrier 30, in a developing region where the latent image carrier and the developer carrier are face-to-face with each other. In such a case, a toner partition member 50 having <=10<12> Ω.cm conductivity is abutted on the developer supplying member 40 and a potential difference is provided between the developer supplying member 40 and the partition member 50, so that the relation between the potentials (V1 ) and (V2 ) of the partition member 50 and the supplying member 40 is 200 v >=V1 -V2 >=0, when the polarity is negative and -200 v <=V1 -V2 <=0, when positive, according to the polarity of the charge of the developer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic copying machine,
For a one-component developing device that converts an electrostatic latent image into a visible image with a one-component developer in a printer, a facsimile, etc., more specifically, it is required to quickly form a thin layer of an appropriate amount of developer on a developer carrier. The present invention relates to a developing device that can be used.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electronic copying machine, a printer, or a facsimile, which forms a latent image on a latent image carrier and visualizes the latent image with a developer to obtain a recorded image, a powdery image is formed. Dry developing devices using a developer are widely used. As such a powdery developer, a two-component developer having a toner and a carrier and a one-component developer without a carrier are known, and a two-component developer using the former two-component developer is known. The development method has the disadvantage that, although a relatively stable and good recorded image can be obtained, the deterioration of the carrier and the fluctuation of the mixing ratio of the toner and the carrier are liable to occur, the maintenance of the apparatus is complicated, and the entire apparatus is liable to be enlarged. have.

[0003] From such a viewpoint, a one-component developing system using a one-component developer which does not have the above-mentioned disadvantages has attracted attention. One-component developer is composed of only toner,
There are toners to which an auxiliary agent is externally added and a mixture of the auxiliary agent as needed. As the toner, there are a magnetic toner in which a magnetic powder is kneaded into each toner particle itself and a non-magnetic toner containing no magnetic material. Here, since the magnetic material is generally opaque, if a color image including full-color or multi-color is formed with magnetic toner, the developed visible image becomes unclear and a vivid color image cannot be obtained. Therefore, particularly for color development, it is desirable to use a one-component development method using a non-magnetic toner.

[0004] By the way, the surface of the developer carrying member generates electric charge due to frictional charging with the toner, but if it does not disappear quickly, it will affect the frictional charging and development of the next rotation,
It causes rise of triboelectric charging and afterimages. Therefore, it is general to control the electrical characteristics of the carrier material, particularly its volume resistance, to 10 ¹³ Ω · cm or less, at which charge is easily lost. (For example, JP-A-276174, JP-A-2-208671, JP-A-3-68974, etc.)

As a method of controlling the electrical characteristics of the carrier material, a method of adding conductive particles to an insulating resin (for example, Japanese Patent Application Laid-Open No.
01375, JP-A-2-105181, JP-A-2-10
9071, JP-A-2-109072, JP-A-2-109
075, JP-A-3-284768, JP-A-3-2009
Japanese Patent Application Laid-Open No. Hei.
-152480, JP-A-2-33166, JP-A-2-8
9075, Japanese Unexamined Patent Application Publication No. 3-95574, etc.), however, there are problems in resistance variation depending on locations, reproducibility of resistance, and the like. As a method for solving the above problem, it has been proposed to use an alcohol-soluble nylon as a resistance control agent (for example, JP-A-64-66674, JP-A-64-66676,
JP-A-2-50187). However, since nylon has a large hygroscopicity, there is a disadvantage that the fluctuation of resistance due to the environment is three orders or more, which changes the developing characteristics. In order to solve these problems, it has been proposed to add a polyether-based material having a low resistance environment, particularly an epichlorohydrin rubber having the lowest volume resistance and a high degree of freedom in resistance control. (Japanese Unexamined Patent Publication No. 1-142569 etc.)

The method of carrying a predetermined amount of the developer on the (conductive) agent carrier generally involves pressing a developer supply member against the developer carrier, for example, 10 ² to 1.
0 ⁶ Ω · cm conductive foam (JP 60-22905
7), elastic body with skin layer (JP-A-60-29060)
And the use of fur brushes (Japanese Patent Application Laid-Open No. Sho 61-42672). These devices provide a frictional charging property between the toner and the supply member and a potential difference between the carrier and the supply member, and carry the developer on the carrier by an electrical effect.

In addition, the chargeability and the potential difference not only achieve the initial toner charge amount and adhesion amount, but also ensure the initial charge amount and adhesion amount promptly at the next charging after development.
That is, it also contributes to improving replenishability. Further, the developer supply member is in contact with a so-called partition member for preventing toner leakage, scattering, and the like from the toner supply section.

[0008]

As described above, when a potential difference is provided between the developer carrying member and the supply member to secure the adhesion amount and the replenishability, the toner holding force on the roller surface of the conductive roller is relatively small. Small (retention is not a true charge,
If the potential difference is increased to increase the replenishing ability (by the mirror image charge), the amount of adhesion exceeds the holding capacity of the roller, and the toner that cannot be carried on the roller leaks from the thin layer member. "Has occurred.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a developing device which does not bleed out and is excellent in charging and replenishment.

[0010]

Means for Solving the Problems The present inventor has found that the above problem can be solved by providing a potential difference between a developer supply member and a toner partition member, and has completed the present invention. That is, the object of the present invention is to provide (1) a non-magnetic one-component developing method in which an auxiliary agent is externally added to a developer carrier having a conductivity of 10 ¹³ Ω · cm or less, which is rotatably driven. The developer is supplied by a developer supply member having a conductivity of 10 ⁶ Ω · cm or less, the developer is carried on the surface of the developer carrying member and transported, and the latent image carrier and the developer carrying member are transported. A developing device used in an image forming method for visualizing an electrostatic latent image formed with the latent image carrier by the developer carried on the developer carrier in a development region facing each other. A toner partition member having a conductivity of 10 ¹² Ω · cm or less is in contact with the developer supply member, and the potential (V ₁ ) of the partition member and the potential ( When V ₂ ) is negatively charged, 200 v ≧ V ₁ −V ₂ ≧
0, a developing device characterized in that a potential difference is provided between the developer supply member and the partition member such that -200v ≦ V ₁ −V ₂ ≦ 0 when the device is positively charged ”and (2) “The amount of charge of the developer when frictionally charged with the partition member is −5 μc / g or less for a negatively chargeable developer and +5 μc / g or more for a positively chargeable developer. The developing device according to the above mode (1) ".

In the image forming method using the developing device of the present invention, the amount of toner supplied to the developer supply member can be controlled by the potential difference from the partition member, so that the toner is not excessively supplied to the developer carrier. , So that welling can be prevented.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image forming method using such a developing device will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing an example of a typical developing device of the present invention. In FIG. 1, the toner (10) contained in a toner tank (not shown) is moved in the axial direction of the developer carrier (30) by a toner supply screw (20). At this time, the toner is supplied to the developer supply member (40) and the partition member (50).
The developer is supplied to a wedge-shaped toner reservoir formed by the developer carrier (30). As for the toner (10) carried to the toner reservoir (14) formed by the partition member (50), an amount of toner corresponding to a predetermined potential difference adheres to the developer supply member (40). At this time, charge is also injected into the toner (10), and the almost uncharged toner (10) has a certain amount of charge, so that the toner (10) is electrostatically attached to the developer supply member (40). , And has a larger adhesion amount than the large amount of toner group existing thereon. Next, the toner moves to a toner reservoir (12) formed by the developer carrier (30). Similarly, due to a potential difference (electric field) between the carrier (30) and the supply member (40), these toners are held on the developer carrier (30). At this time, an almost uncharged toner group is similarly supplied. However, since there is a difference in toner charge amount, the partition member (5
The toner charged in the toner reservoir of 0) is preferentially carried on the developer carrying member (30). Therefore, the developer supply member (40) is stored in the toner pool of the partition member (50).
By controlling the above toner amount, the toner is not excessively supplied to the carrier (30) and the charge amount is large to some extent, so that the adhesive force on the carrier (30) also increases,
Springing can also be prevented. However, if the potential difference between the partition member and the supply member exceeds 200 V, the toner adhesion amount on the carrier becomes too small (less than 0.5 mg / cm), and conversely, a problem occurs.

The definition of the "partition member" in the present invention refers to a member that prevents toner from leaking from the toner storage section to another section and includes a section that comes into contact with the developer supply member. In FIG. 1, the unit frame itself is a partition member (50).
For example, a blade-shaped member (60) may be further provided on the unit frame as shown in FIG. 2, or a brush-shaped member (70) is provided as shown in FIG. 4, a roller-shaped member (80) may be provided as shown in FIG. 4, or a resin or rubber sheet (8) may be provided at the supply member contact portion of the unit frame as shown in FIG.
0) may be attached, or a painted portion (80) may be provided.

By controlling the resistance of these partition members, the effect is increased. Resistance is 10 ¹² Ω · cm or less,
Preferably, it is 10 ¹⁰ Ω · cm or less. 10 ¹³ Ω · cm
Above this, it becomes difficult to control the toner adhesion. As the conductivity imparting agent when using organic polymers for the partition member, metal powders such as Ni and Cu, carbon black, tin oxide, zinc oxide, molybdenum oxide, antimony oxide, metal oxides such as titanium oxide and the like A conductive oxide such as a doping material or a surface plating material, or a medium resistance polymer such as epichlorohydrin rubber, a nitrile butadiene copolymer, a polyetheresteramide, or a boron polymer is preferably used.

Next, the partition members (50), (60), (7)
0) and (80) will be described. If the frictional charging property of the partitioning member is excessively biased toward the charging polarity side of the developer, toner of opposite polarity is generated, which causes the background of the photoconductor to be stained, which is not good. -5 for negatively chargeable developer
μc / g or less, and preferably +5 μc / g or more for a positively chargeable developer. The measuring method of q / m is as follows.

Measuring Method Two measuring samples are prepared by coating and affixing a measuring sample on the surface of a 20φ diameter roller, and are mounted on the apparatus shown in FIG. The roller is rotated at a roller gap of 50 μm and a roller linear velocity ratio of 1:05. Approximately 1 mg of toner is adhered thereto, and after 5 minutes rotation, the roller is stopped, and the toner q / m on the roller is measured.

[0017]

【Example】

Examples and Comparative Example 1 A negatively chargeable toner will be described as an example. The partition member (5 in FIG. 1)
0) was A1 metal, the developer supply member (30) was a urethane sponge roller (10 ⁶ Ω · cm), and the thinning member (80) was a SUS blade, and the following developer carrier was mounted on a development unit. . The toner used was negatively charged.

Method for Producing Developer Carrier Prescription Acrylic-modified silicone resin (KR9706; Shin-Etsu Chemical) 100 parts by weight Epichlorohydrin rubber (Epichromer CG; Daiso) 60 parts by weight Curing agent (SH6020; Toray silicone) 10 parts by weight Coating method: spray Coating and curing conditions: 150 ° C./1 hour After curing, polished to a film thickness of 30 μm and a volume resistance of 2 × 10 ¹²
An Ω · cm support was obtained. Developer carrier potential -150
v, the developer supply member potential -350v, the SUS blade potential -350v, and the potential of the partition member is changed as shown in the table below to obtain the springing property, q / m on the developer carrier (per unit weight). The toner charge amount) and m / a (toner adhesion amount per unit area) were evaluated.

[0019]

[Table 1] Source rank evaluation method Rank ○ ~ No source at all △ ~ Slightly sourced so as not to be quantifiable × ~ Sourced at a large amount as the source toner drops under the blade (allowable up to Δ) Potential difference is 0v If it falls below, the springability deteriorates. q /
FIG. 6 shows the results of m and m / a. If the potential difference exceeds 200 V, the amount m / a of adhesion on the carrier exceeds the allowable limit.

Examples and Comparative Example 2 An acrylic resin (polymethyl methacrylate) and a blended product of a fluororesin and an acrylic resin (Novafusso; Dainippon Color Co., Ltd.) were used as a partition member at each blend ratio (Novafusso /
PMMA) and 10 parts by weight of carbon black (based on 100 parts by weight of resin) dispersed as conductive particles, diluted with MEK / ethyl acetate solvent, and applied to the supply member contact portion of FIG. )did. Volume resistance is 10 ⁵ Ω · cm
Met. Using the same toner as described above and the OPC photoreceptor, background contamination of the photoreceptor was measured. The toner q / m was measured in the same manner as described above.

Background Stain Measurement Method A transparent tape is pressed against a background portion of a copy paper on which development and transfer have been performed, and the toner adhered to the copy paper is robbed by the transparent tape, and the transparent tape holding the toner is attached to a white paper. A new tape is similarly stuck on blank paper, and the density is measured with a Macbeth densitometer. ΔID = ID (toner attached tape) −ID
(New tape), allowable limit is 0.03.

[0022]

[Table 2]

[0023]

As described above in detail and specifically,
The developing device of the present invention prevents the toner from flowing out from the thin layer forming member by setting the potential difference between the developer supply member and the partition member within a predetermined range, and prevents toner from adhering on the developer carrying member. By controlling the frictional charging property between the partition member and the developer, an extremely excellent effect of preventing background contamination of the photoreceptor can be exhibited.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a developing device according to the present invention.

FIG. 2 is a view showing an example of a partition member provided on a developing unit frame of the present invention.

FIG. 3 is a view showing another example of a partition member provided on the developing unit frame of the present invention.

FIG. 4 is a view showing still another example of the partition member provided on the developing unit frame of the present invention.

FIG. 5 is a view showing still another example of the partition member provided on the developing unit frame of the present invention.

FIG. 6 shows an example of a toner charge amount per unit weight (q / m; μc / g) and a toner adhesion amount per unit area (m / a; mg / cm ² ) in the example of the developing device of the present invention. FIG.

FIG. 7 is an example of an apparatus for measuring a charged state of toner by the developing device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Toner 12 Toner pool 14 Toner pool 20 Toner conveyance screw 21 Toner collection screw 30 Developer carrier 40 Supply member 50 Partition member 60 Blade 70 Brush 80 Roller 90 Sheet (pasting)

Claims (2)

[Claims] 1. A non-magnetic one-component developer in which an auxiliary agent is externally added to a developer carrier having a conductivity of 10 ¹³ Ω · cm or less, which is driven to rotate, is supplied to a developer carrier of 10 ⁶ Ω · cm. The developer is supplied by a developer supply member having the following conductivity, the developer is carried on the surface of the developer carrier and transported, and the latent image carrier and the developer carrier are opposed to each other in a developing area. ,
A developing device used in the image forming method of a visible image by the developing agent carried an electrostatic latent image latent image bearing member is formed on the developer carrying member, 10 ¹² to the developer supply member
Omega · cm toner partition member having the conductive are abutting, the charge polarity of the developer, the potential of the partition member (V ₁₎ and the potential of the supply member (V ₂₎ is negatively chargeable Hour 2
00v ≧ V ₁ −V ₂ ≧ 0, -200v ≦ V when positively charged
A developing device, wherein a potential difference is provided between the developer supply member and the partition member such that ₁₋ V ₂ ≦ 0. 2. The amount of charge of the developer when frictionally charged with the partition member is −5 μc / g for a negatively chargeable developer.
2. The developing device according to claim 1, wherein the value is +5 μc / g or more for a positively chargeable developer.