JPH07199634A - Developing device - Google Patents

Abstract

PURPOSE:To provide a developing device which prevents deterioration of an image resulting from an insufficient amount of carry and unsatisfactory electrification of toner by reducing an amount of toner sticking to toner-carrying members and stresses on the toner. CONSTITUTION:The developing device 10 is equipped with the toner-carrying members 3 and 4 for holding the toner inside a toner tank, supplying the toner to a toner replenishment roller 2, and recovering the toner to the toner tank, a toner-restricting member 5 provided in the vicinity of the toner replenishment roller 2, and a developing roller 1 which is in contact with the toner replenishment roller 2. In the developing device 10, the surfaces of the toner-carrying members 3 and 4 are made of a material having the same electrification polarity as that of the toner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device in an electrophotographic apparatus.

[0002]

2. Description of the Related Art In an image forming apparatus for forming an electrostatic latent image on a latent image carrier and visualizing it with a developer to obtain a recorded image, a dry developing apparatus using a powdery developer is used. Is widely used. As the developer, a two-component system having a toner and a carrier and a one-component system containing no carrier are known, and a one-component system advantageous in terms of downsizing of a developing device, cost reduction, or colorization is noted. ing. In particular, in printers and facsimiles, the layout of each unit and the miniaturization of the units have been studied in accordance with the miniaturization of the entire apparatus. In a developing device using a one-component developer, there are a non-magnetic system and a magnetic system, and in particular, in the non-magnetic system, since the toner is carried on the developing roller by using only electrostatic force, How to properly charge the toner with proper polarity is important for obtaining a high quality image. Also in the magnetic method, the charging polarity of the toner is important.

[0003]

Under such circumstances, the size of the developing device has been reduced by carrying toner by a carrying member from a toner tank arranged beside the developing device. A screw member made of metal or resin is generally used as the conveying member. The toner is insulative and has been made smaller with the recent improvement in image quality and color, but over time, the toner adheres to the screw due to the image force of the toner itself or the electrostatic force due to frictional charging with the screw. In addition to causing a decrease in the carrying force of the toner, the proper charging polarity of the toner cannot be obtained, which causes image defects such as background stains on the latent image carrier (photoconductor). is there.

[0004]

Therefore, in the invention described in claim 1, the surface of the toner carrying member is made of a material having the same charge polarity as the toner, and in the invention described in claim 2, the toner carrying member itself is made of toner. In the third aspect of the invention, the surface of the toner conveying member has irregularities.

[0005]

According to the present invention, the surface of the toner conveying member or the toner conveying member itself is made of a material having the same charge polarity as that of the toner. Adhesion due to is suppressed. According to the third aspect of the present invention, since the surface of the toner conveying member is formed to be uneven, the frictional force between the toner and the toner conveying member is reduced, and the toner is prevented from adhering to the toner conveying member due to electrostatic force.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A developing device indicated by reference numeral 10 in FIG. 1 includes a developing roller 1 and a toner replenishing roller 2 inside a casing 6, a toner replenishing screw 3 and a toner collecting screw 4 as toner conveying members, and a vicinity of the toner replenishing roller 2. The toner regulating member 5 arranged in the above is provided. The toner supply screw 3 is arranged above the toner supply roller 2, and the toner recovery screw 4 is arranged at the bottom of the developing device 10.

As shown in FIGS. 2 and 3, the toner replenishing screw 3 and the toner recovering screw 4 are rotatable in such a manner that substantially the entire surface in the extending direction is formed in a spiral shape and the surfaces thereof are charged to the toner. And a protrusion / depression smaller than the toner particles.

In the developing device 1, a non-magnetic toner 8 as a one-component toner is conveyed from a toner tank 7 arranged beside the developing device 1 by a toner replenishing screw 3 and a toner collecting screw 4 by the toner tank 7. Are collected and circulated. The toner 8 conveyed by the toner replenishing screw 3 adheres to the peripheral surface of the developing roller 1 by the toner replenishing roller 2, is regulated to a uniform thickness by the toner regulating member 5, and an electrostatic latent image is formed (not shown). A visible image is formed by adhering to a latent image carrier 11 such as a photosensitive drum or a belt.

The toner 8 dropped by the toner regulating member 5 is collected in the toner tank 7 by the toner collecting screw 4. The alternate long and short dash line indicated by reference numeral 9 indicates the conveyance path of the toner 8. Although a non-magnetic toner is used here, a magnetic toner may be used.

As a material for the toner supply screw 3 and the toner recovery screw 4, when negatively charged toner is used, polytetrafluoroethylene, polyvinylidene fluoride, fluorine-containing resins such as PFA, FEP, ETFE and CTFE, PS, ABS, Styrenic resin such as AS,
Materials such as silicone resin, silicone rubber, and polycarbonate resin are desirable. On the other hand, when positively charged toner is used, acrylic resin, polyamide resin, etc. are desirable.

When only the surfaces of the toner supply screw 3 and the toner recovery screw 4 are made of a material having the same charging polarity as the toner 8, the toner supply screw 3 and the toner recovery screw 4 themselves are formed by painting or dipped. When it is formed of a material having the same charging polarity as that of No. 8, it is formed by using a molding method such as injection molding. The irregularities on the surfaces of the toner supply screw 3 and the toner recovery screw 4 are preferably equal to or smaller than the average particle diameter of the toner 8, and are formed by sandblasting.

A specific combination example of the toner replenishing screw 3, the toner collecting screw 4 and the toner having such a configuration will be described. The toner supply screw 3 and the toner recovery screw 4 are collectively referred to as "screw".

(First embodiment) Toner: Negative charging property Screw: SUS Screw surface: PFA resin (Second embodiment) Toner: Negative charging property Screw: SUS Screw surface: PS (Third embodiment) Toner : Negative charging property Screw: ABS (4th embodiment) Toner: Positive charging property Screw: SUS Screw surface: Acrylic resin (PMMA) (5th embodiment) Toner: Positive charging property Screw: Polyamide resin (nylon 6) (Comparative Example 1) Toner: Negative charging property Screw: SUS (without sandblast treatment) (Comparative example 2) Toner: Positive charging property Screw: SUS (without sandblast treatment) The first and second examples are made of metal. The surface of the screw is made to have the same charging polarity as the negatively charging toner. Formed in fees, the third embodiment is obtained by forming a screw itself a material having a negatively charged toner the same charge polarity. In the fourth embodiment, the surface of a metal screw is made of a material having the same charging polarity as that of a positive charging toner, and in the fifth embodiment, the screw itself is made of a material having the same charging polarity as a positive charging toner. It was formed in.

Further, the surface of the screw of the first to fifth embodiments is sandblasted, and is provided with irregularities having an average particle size of the toner or less. Comparative Examples 1 and 2 show conventional screws in which a commonly used stainless steel screw that is not subjected to sandblasting and toners having different charging electrodes are combined.

When a 1000-sheet passing test was conducted using the developing device having the construction of each of the examples and comparative examples described above, the results shown in Table 1 were obtained.

[0016]

[Table 1]

From Table 1 in the first to fifth embodiments,
Regardless of the charging electrode of the toner, neither the adhesion of the toner to the screw nor the background stain due to the adhesion to the latent image carrier 11 was measured, and a good image state could be obtained. In this case, not only the toner adhered to the screw but also the background stain due to the toner adhered to the latent image carrier 11 was observed. In particular, in Comparative Example 1 using a toner having a negative charging property, the phenomenon was remarkably observed.

As described above, the material and the surface of the screw are formed of a material having the same charging polarity as the charging electrode of the toner, or the surface of the screw formed of these materials is provided with irregularities having an average particle diameter of the toner or less. By forming them, the screw and the toner repel each other and the contact surface between the screw surface and the toner becomes small, so that the frictional electrification power and the frictional force can be reduced and the adhesion of the toner to the screw can be reduced. it can.

[0019]

According to the present invention, the surface of the toner conveying member or the conveying member itself is made of a material having the same charging polarity as the toner, so that electrostatic force adhesion due to strong frictional charging between the toner and the toner conveying member is prevented. can do. Therefore, it is possible to maintain a stable toner conveyance amount with the passage of time, prevent the generation of poorly charged toner, and obtain a good image. Further, by forming the unevenness of the average particle size of the toner or less on the surface of the toner transport member, the frictional force between the toner and the toner transport member is reduced, electrostatic force can be prevented from adhering, and the stress on the toner and the transport amount can be reduced. Can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a developing device in which the present invention is adopted.

FIG. 2 is a configuration diagram showing a toner conveyance path.

FIG. 3 is a front view of a toner regulation member.

[Explanation of symbols]

 1 Developing Roller 2 Toner Supplying Roller 3, 4 Toner Conveying Member 7 Toner Tank 8 Toner 10 Developing Device

Claims (3)

[Claims] 1. A toner carrying member for carrying toner in a toner tank, supplying the toner to a toner replenishing roller and collecting the toner in the toner tank, and a toner regulating member provided in the vicinity of the toner replenishing roller. A developing device having a developing roller in contact with the toner replenishing roller, wherein the surface of the toner conveying member is made of a material having the same charging polarity as the toner. 2. A toner carrying member for carrying toner in a toner tank, supplying the toner to a toner replenishing roller and collecting the toner in the toner tank, a toner regulating member in contact with the toner replenishing roller, and the toner replenishing. A developing device having a developing roller in contact with a roller, wherein the toner conveying member is made of a material having the same charge polarity as the toner. 3. The developing device according to claim 1, wherein the surface of the toner conveying member is formed with irregularities having an average particle diameter of toner or less.