JPH0361971A - 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 [Industrial Field of Application] The present invention is utilized in the technical field of developing devices, and in particular, the present invention is applied to the technical field of developing devices, and particularly to the development of a developing roll that conveys developer to a developing section and a developer container that accommodates the developing roll. between.

The present invention relates to a device having a sealing member that prevents developer from leaking at the end of the developing roll.

[Prior Art] In this type of developing device, if developer (hereinafter referred to as toner) spreads outside the developing area in the longitudinal direction of the developing roll or leaks, it may cause adverse effects such as toner scattering and staining. Therefore, conventionally, an elastic member such as moltoprene or felt was brought into close contact with the surface of both end portions of the developing roll over almost the entire circumference to prevent leakage at the end portions.

Furthermore, if a porous elastic body such as the above-mentioned Moltoprene is used, there is a problem in that it causes toner clogging and hinders subsequent toner removal, so it is recommended to use felt made of a material that has low friction with the developing roll. There were also many.

[Problems to be Solved by the Invention] However, with such conventional sealing members, it is difficult to ensure dimensional accuracy at the end portions, and since the sealing member has high flexibility, the sealing member and the developing roll may rub against each other due to rotation of the developing roll. As a result, toner enters the developing roller, and the toner ends up being applied to the non-developing area on the developing roll.

Furthermore, if the frictional charging characteristics between the toner and the sealing member are not appropriate, the toner will be frictionally charged to a polarity opposite to the predetermined charging polarity (hereinafter referred to as reverse toner), and the end portions on the photoreceptor drum will be A problem has arisen in that a reverse fog is developed in the image area. This leads to toner scattering and staining, and in developing devices that use a member that contacts the photoreceptor drum to transfer the image, such as a transfer roller, this causes the problem that the toner is transferred to a non-image area on the transfer paper as an inverted fog. Become.

A specific example will be shown and explained below. As an end seal member,
Generally, Teflon (tetrafluoroethylene resin, Teflon: trade name of DuPont) is often used. This is because the so-called squeal (fricative noise) is eliminated and the driving torque is also reduced. However, when a negatively chargeable toner is used, the toner is positively charged due to friction with the Teflon felt, resulting in reverse fogging.

The present invention solves the problems of such conventional devices,
It is an object of the present invention to provide a developing device that prevents toner from being charged to the opposite polarity due to friction with a sealing member and eliminates reverse fog.

[Means for Solving the Problems] According to the present invention, the above objects include: a container having an opening on the side and storing a developer; A developing device including a developing roll that carries and conveys developer, and a sealing member that contacts the developing roll and seals the developer with the container at an end of the developing roll, comprising: a developing roll of the sealing member; This is achieved by the fact that the surface that contacts the surface is formed of a member that has charging characteristics with respect to the developer that are opposite to those of the developer.

[Function] In the above-described particular aspect of the present invention, the developer at both ends of the developing roll is prevented from being charged to the opposite polarity due to friction between the developer and the sealing member having the opposite charging characteristic. .

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

FIG. 1 is a sectional view of the apparatus of the first embodiment, and FIG. 2 is a perspective view showing the developing roll and seal member of the apparatus shown in FIG.

In FIG. 1, the photoreceptor drum l is charged with a negative potential by a primary charger (not shown), for example, Vd=-650.
After being charged to V, it is exposed to light by an exposure means (not shown) such as a laser beam to form a negative latent image (for example, potential vi = -t
oov) has become popular. In such a photosensitive drum, this latent image is visualized by reversal development using a developing device using negatively charged high resistance component magnetic toner.

The developing roll 2, which forms a developing section in close opposition to the photoreceptor drum 1, is made of a non-magnetic material such as stainless steel or aluminum, and is supplied with the magnetic toner T (developer) in the container 4. By rotating in the direction of the arrow, the toner T is supported and conveyed on its circumferential surface. A regulating member 5 made of a magnetic material such as iron is disposed directly above the developing roll 2 at a uniform interval from the developing roll 2. In addition, the magnetic flux of the magnet 6 in the developing roll 2 acts in a concentrated manner with the regulating member 5, forming a magnetic curtain that restrains the magnetic developer, thereby allowing the developer layer 3 of a predetermined thickness to be developed. It is formed on the circumferential surface of the roll 2. The thickness of the developer layer 3 is desirably thin enough to be narrower than the distance between the developing roll 2 and the photosensitive drum 1 in the developing section where the photosensitive tram 1 receives developer from the developing roll 2. But it is not limited to this.

The developing roll 2 is supplied with an AC voltage (for example, a rectangular wave 14
00Vpp, 1800Hz) and DC voltage (Vde= -
5oov) is applied to form an oscillating electric field in the developing section, thereby making it possible to develop the electrostatic latent image.

At both ends of the developing roll 2, seal members IO fixed to the container 4 are in close contact with the back side (inside the container) of the developing roll 2, as shown in FIG. leakage from the edge of the developing roll.

In this embodiment, as shown in FIG. 3, the sealing member 10 is made of wool felt IOA on the container side and made of fur felt IOB on the upper layer, that is, the surface in contact with the developing roll 2. The fur felt 10B exhibits a charging characteristic of opposite polarity (positive polarity) to the toner, and has a property of charging the toner to a negative polarity. Low temperature, low humidity environment (tS℃
, 10% RH), when the toner was rubbed against fur felt, the toner was -0.5 to 1. OKV was charged.

If the sealing member 10 of the embodiment having such characteristics is used, the adhesion of the developing roll 2 and the end forming of the sealing member 10 will be incomplete, and a small amount of toner will be trapped between the sealing member 10 and the developing roll 2. Even if the toner leaks, the toner will be negatively charged due to friction with the sealing member, so no reversed toner will be generated.

Further, since fur felt has a good surface slipperiness, the driving torque when the developing roll rotates is small, and so-called sleeve noise was at a sufficiently low level.

Materials for the felt that charges the toner in this example to a predetermined polarity (negative) include wool, Tetron (polyester of terephthalic acid and ethylene glycol), nylon (Polyact), etc. The material should be selected in consideration of the driving torque, frictional noise, etc.

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

In the previous example, the sealing member used was one in which the container side was made of wool felt and the upper layer, that is, the surface in contact with the developing roll, was made of fur felt. This is to select the charging characteristics of the seal member and the toner, as well as to satisfy the slipperiness of the developing roll, frictional noise, and adhesion of the seal. The sealing member is made only of wool felt. To this end, the developing roll is provided with lubricity to improve slipperiness and reduce frictional noise.

FIG. 4 shows the developing device of this embodiment. The basic structure and operation are the same as those of the previous embodiment, but the difference is that the sealing member 20 is made of wool felt. Wool felt charges the toner to a negative polarity, so there is no generation of reversed toner.However, since the friction is large, if the developing roll is made of smooth aluminum, the drive torque of the sleeve and friction noise will worsen. Therefore, conductive particles (carbon) and conductive particles (graphite) that have lubricity
By coating at least the sealing member contact portion of the surface of the developing roll 21 with a resin mixed with the developing roll 21, the developing roll itself has lubricity, thereby reducing friction with the sealing member. To give a specific example, a conductive paste with the following formulation is coated on the surface of an aluminum developing roll at least in the area where the sealing member contacts by a spray method to form a conductive resin with a film thickness of 5 wells and a volume resistance of 5.0 x 10°Ωcm. formed a layer.

Resin: Phenol resin 50 overlapping parts Carbon: CONDUCTEX 975UB (product name) manufactured by Columbia Carbon Co., Ltd. 10 overlapping parts: Graphite: CP manufactured by Nippon Graphite Co., Ltd.
S (Product name) For average particle size 5.0 1I40 overlapping parts Diluent: Isopropyl alcohol 250 overlapping parts By using such a developing roll 21, even if wool felt is used as the sealing member 20. There are no problems with driving torque, friction noise, etc., and it is possible to reduce reversal fog, and it is also possible to reduce costs.

It goes without saying that a sealing member made of other materials such as Tetron may also be used in the developing roller coated with a conductive resin.

[Effects of the Invention] As described above, the present invention provides a sealing member for preventing toner leakage from both ends of the developing roll by charging the surface of the sealing member in contact with the developing roll with a charge that is opposite to the charging property of the developer. Since it is made of a material with special characteristics, it prevents the toner from being charged to the opposite polarity due to friction with the sealing member.
This has the effect of eliminating reverse fog.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the apparatus according to the first embodiment of the present invention, FIG. 2 is a perspective view showing the developing roll and sealing member of the apparatus shown in FIG. 1, and FIG. 3 is an enlarged perspective view showing the sealing member of FIG. 2. Figure, 4th
The figure is a sectional view showing the device of the second embodiment. 2:21...Developing roll 4...Container 10:20---Sealing member

Claims (1)

[Scope of Claims] A container having an opening on the side and storing a developer, a developing roll having a portion protruding from the opening and being housed in the container and carrying the developer on its surface for transport; In a developing device having a sealing member that contacts the developing roll and seals the developer with the container at the end of the developing roll, the surface of the sealing member that contacts the surface of the developing roll seals the developer with respect to the developer. A developing device characterized in that it is formed of a member having charging characteristics opposite to those of the agent.